Front end motor-generator system and hybrid electric vehicle operating method

Abstract

A system and method are provided for hybrid electric internal combustion engine applications in which a motor-generator, a switchable coupling and a torque transfer unit are arranged co-axially-arranged with the front end of the engine crankshaft in the constrained environment in front of an engine in applications such as commercial vehicles, off-road vehicles and stationary engine installations. The motor-generator is preferably laterally offset from the switchable coupling. The switchable coupling is an integrated unit in which a crankshaft vibration damper, an engine accessory drive pulley and a clutch overlap with an axial depth nearly the same as a conventional belt drive pulley and engine damper. The system includes an electrical energy store that receives energy generated by the motor-generator when the coupling is engaged. When the coupling is disengaged, the motor-generator may drive the pulley portion of the clutch-pulley-damper to drive engine accessories using energy returned from the energy store.

Claims

1. An integrated switchable coupling of a hybrid electric arrangement for an internal combustion engine, comprising: an engine-side portion configured to be coupled for co-axial rotation to a rotatable shaft of the engine; a drive-side portion configured to drive an engine accessory drive, to be selectively engaged with the engine-side portion, and to be driven by an electric motor at a front side of the drive-side portion opposite a rear side of the drive side portion facing the rotatable engine shaft; and an engagement actuator configured to selectively engage the drive side portion with the engine-side portion, wherein the drive-side portion concentrically surrounds at least a portion of the engagement actuator along a coupling rotation axis, the rotatable engine shaft is an engine crankshaft, the engine-side portion includes a crankshaft damper portion, the drive-side portion includes a pulley portion having on an outer circumference at least one accessory drive surface configured to engage an accessory drive, the engagement actuator is a clutch, the clutch including an engine-side engagement portion, and a drive-side engagement portion at least one of coupled to and integrally formed with the drive-side portion of the integrated switchable coupling, and the at least one accessory drive surface is configured to drive an accessory drive belt.

2. The integrated switchable coupling of claim 1, wherein an outer circumference of the engine-side portion includes a further accessory drive surface.

3. The integrated switchable coupling of claim 1, wherein the clutch is a dog clutch.

4. The integrated switchable coupling of claim 1, wherein the clutch is a plate clutch.

5. The integrated switchable coupling of claim 4, wherein the plate clutch is a multi-plate clutch.

6. The integrated switchable coupling of claim 1, further comprising: a clutch actuator configured to axially displace at least one of the clutch engine-side portion and the clutch drive-side portion into and out of engagement with the other of the at least one of the clutch engine-side portion and the clutch drive-side portion.

7. The integrated switchable coupling of claim 6, wherein the clutch actuator is a hydraulic actuator.

8. The integrated switchable coupling of claim 7, wherein the hydraulic actuator includes a hydraulic pressure supply arranged to apply hydraulic pressure to the at least one of the clutch engine-side portion and the clutch drive-side portion, and at least one solenoid-controlled valve arranged to control at least one of application and release of the hydraulic pressure to engage or disengage the clutch.

9. The integrated switchable coupling of claim 6, wherein the clutch actuator is an electric actuator.

10. The integrated switchable coupling of claim 9, wherein the electric actuator is an electric solenoid configured to be co-axially facing the front side of the drive-side portion and aligned to actuate a clutch actuation shaft to axially displace the at least one of the clutch engine-side portion and the clutch drive-side portion.

11. The integrated switchable coupling of claim 1, wherein the clutch is biased into an engaged position by a biasing element.

12. An integrated switchable coupling of a hybrid electric arrangement for an internal combustion engine, comprising: an engine-side portion configured to be coupled for co-axial rotation to a rotatable shaft of the engine; a drive-side portion configured to drive an engine accessory drive, to be selectively engaged with the engine-side portion, and to be driven by an electric motor at a front side of the drive-side portion opposite a rear side of the drive side portion facing the rotatable engine shaft; an engagement actuator configured to selectively engage the drive side portion with the engine-side portion; and a clutch actuator configured to axially displace at least one of the clutch engine-side portion and the clutch drive-side portion into and out of engagement with the other of the at least one of the clutch engine-side portion and the clutch drive-side portion, wherein the drive-side portion concentrically surrounds at least a portion of the engagement actuator along a coupling rotation axis, and the clutch actuator is a pneumatic actuator.

13. The integrated switchable coupling of claim 12, wherein the pneumatic actuator is configured to be co-axially facing the front side of the drive-side portion and aligned to actuate a clutch actuation shaft to axially displace the at least one of the clutch engine-side portion and the clutch drive-side portion.

14. An integrated switchable coupling of a hybrid electric arrangement for an internal combustion engine, comprising: an engine-side portion configured to be coupled for co-axial rotation to a rotatable shaft of the engine, a drive-side portion configured to drive an engine accessory drive, to be selectively engaged with the engine-side portion, and to be driven by an electric motor at a front side of the drive-side portion opposite a rear side of the drive side portion facing the rotatable engine shaft, and an engagement actuator configured to selectively engage the drive side portion with the engine-side portion, wherein the drive-side portion concentrically surrounds at least a portion of the engagement actuator along a coupling rotation axis, the rotatable engine shaft is an engine crankshaft, the engine-side portion includes a crankshaft damper portion, the drive-side portion includes a pulley portion having on an outer circumference at least one accessory drive surface configured to engage an accessory drive, the engagement actuator is a clutch, the clutch including an engine-side engagement portion, and a drive-side engagement portion at least one of coupled to and integrally formed with the drive-side portion of the integrated switchable coupling, and the pulley portion of the drive-side portion of the integrated switchable coupling extends axially around the clutch.

15. The integrated switchable coupling of claim 14, wherein the pulley portion of the drive-side portion of the integrated switchable coupling extends axially around the damper portion of the engine-side portion of the integrated switchable coupling.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIGS. 1A and 1B are schematic illustrations of an overall view of the arrangements of an FEMG system in accordance with an embodiment of the present invention.

(2) FIGS. 2A-2C are cross-section views of an embodiment of a clutch-pulley-damper and assembled FEMG components in accordance with the present invention.

(3) FIGS. 3A-3C are views of the components of the FIGS. 2A-2C clutch-pulley-damper unit.

(4) FIG. 4 is a cross-section view of another embodiment of a clutch-pulley-damper unit in accordance with the present invention.

(5) FIG. 5 is detailed cross-section view of a bearing arrangement at the clutch-pulley-damper unit end of an FEMG gearbox in accordance with an embodiment of the present invention.

(6) FIGS. 6A-6C are oblique views of an FEMG drive unit in the form of a gearbox in accordance with an embodiment of the present invention.

(7) FIG. 7 is a cross-section view of the FEMG gearbox of FIGS. 6A-6C.

(8) FIG. 8 is exploded view of an FEMG clutch pneumatic actuator diaphragm arrangements in accordance with an embodiment of the present invention.

(9) FIG. 9 is an oblique view of another embodiment of an FEMG gearbox in accordance with the present invention.

(10) FIG. 10 is a schematic illustration of an FEMG gearbox mounting arrangement in accordance with an embodiment of the present invention.

(11) FIG. 11 is a schematic illustration of an FEMG gearbox mounting arrangement in accordance with an embodiment of the present invention.

(12) FIG. 12 is a schematic illustration of relationships between an engine and an FEMG gearbox mounting bracket in accordance with an embodiment of the present invention.

(13) FIG. 13 is a schematic illustration of relationships between an engine, FEMG gearbox and an FEMG gearbox mounting bracket in accordance with an embodiment of the present invention.

(14) FIG. 14 is an oblique view of an FEMG gearbox mounting bracket as in FIGS. 12-13.

(15) FIG. 15 is an oblique view of a motor-generator in accordance with an embodiment of the present invention.

(16) FIG. 16 is a graph of power and torque generated by an example motor-generator in accordance with an embodiment of the present invention.

(17) FIG. 17 is an oblique phantom view of a cooling arrangement of a motor-generator in accordance with an embodiment of the present invention.

(18) FIG. 18 is a block diagram of FEMG system control and signal exchange arrangements in accordance with an embodiment of the present invention.

(19) FIG. 19 is a schematic illustration of AC and DC portions of the electrical network of an FEMG system in accordance with an embodiment of the present invention.

(20) FIG. 20 is a schematic illustration of an FEMG system-controlled power transistor arrangement for AC and DC conversion in accordance with an embodiment of the present invention.

(21) FIG. 21 is a schematic illustration of an FEMG system-controlled forward DC voltage converter arrangement in accordance with an embodiment of the present invention.

(22) FIG. 22 is a schematic illustration of a high voltage bi-directional DC/DC converter in accordance with an embodiment of the present invention.

(23) FIG. 23 is a graphical illustration of voltage and current responses across the bi-directional DC/DC converter of FIG. 22.

(24) FIG. 24 is an oblique view of a power electronics arrangement integrated into a motor-generator in accordance with an embodiment of the present invention.

(25) FIG. 25 is a battery management system state of charge estimation control loop in accordance with an embodiment of the present invention.

(26) FIG. 26 is a flow chart of accessory operating speed selection in accordance with an embodiment of the present invention.

(27) FIG. 27 is a flow chart of a control strategy for operation of a motor generator and engine accessories independently of an engine in accordance with an embodiment of the present invention.

DETAILED DESCRIPTION OF THE DRAWINGS

A Front End Motor-Generator System Embodiment

(28) FIG. 1A is a schematic illustration showing components of an embodiment of an FEMG system in accordance with the present invention. FIG. 1B is a schematic illustration of several of the FEMG system components in the chassis of a commercial vehicle. In this arrangement, the engine accessories (including air compressor 1, air conditioning compressor 2 and engine cooling fan 7 arranged to pull cooling air through engine coolant radiator 20) are belt-driven from a pulley 5. The pulley 5 is located co-axially with a damper 6 coupled directly to the crankshaft of the internal combustion engine 8. The accessories may be directly driven by the drive belt or provided with their own on/off or variable-speed clutches (not illustrated) which permit partial or total disengagement of an individually clutch-equipped accessory from the belt drive.

(29) In addition to driving the accessory drive belt, the pulley 5 is coupled a drive unit having reduction gears 4 to transfer torque between a crankshaft end of the drive unit and an opposite end which is coupled to a motor-generator 3 (the drive unit housing is not illustrated in this figure for clarity). A disengageable coupling in the form of a clutch 15 is arranged between the crankshaft damper 6 and the pulley 5 (and hence the drive unit and the motor-generator 3). Although schematically illustrated as axially-separate components for clarity in FIG. 1A, in this embodiment the crankshaft 6, clutch 15 and pulley 5 axially overlap one another at least partially, thereby minimizing an axial depth of the combined pulley-clutch-damper unit in front of the engine. Actuation of the pulley-clutch-damper clutch 15 between its engaged and disengaged states is controlled by an electronic control unit (ECU) 13.

(30) On the electrical side of the motor-generator 3, the motor-generator is electrically connected to a power invertor 14 which converts alternating current (AC) generated by the motor-generator output to direct current (DC) useable in an energy storage and distribution system. The power invertor 14 likewise in the reverse direction converts direct current from the energy storage and distribution system to alternating current input to power the motor-generator 3 as a torque-producing electric motor. The inverter 14 is electrically connected to an energy storage unit 11 (hereafter, an energy store), which can both receive energy for storage and output energy on an on-demand basis.

(31) In this embodiment, the energy store 11 contains Lithium-based storage cells having a nominal charged voltage of approximately 3.7 V per cell (operating range of 2.1 V to 4.1 V), connected in series to provide a nominal energy store voltage of 400 volts (operating voltage range of approximately 300 V to 400 volts) with a storage capacity of between approximately 12 and 17 kilowatt-hours of electrical energy. Alternatively, the cells may be connected in series and parallel as needed to suit the application. For example, 28 modules with four series-connected cells per module could be connected in series and in parallel to provide an energy store with the same 17 kilowatt hours of stored energy as the first example above, but with a nominal operating voltage of 200 V volts and twice the current output of the first example.

(32) In addition to the relatively high-capacity, low charge-discharge rate Lithium-based storage cells, the energy store 11 in this embodiment includes a number of relatively low-capacity, high charge-discharge rate of super capacitors to provide the energy store the ability over short periods to receive and/or discharge very large electrical currents that could not be handled by the Lithium-based storage cells (such cells being typically limited to charge/discharge rates of less than 1 C to only a few C).

(33) FEMG System Hardware Assembly Embodiment.

(34) FIGS. 2A-2C show cross-section views of an embodiment of the clutch-pulley-damper unit 19 and of an assembled configuration of FEMG system hardware with this clutch-pulley-damper embodiment. In this embodiment the gearbox 16 containing reduction gears 4 receives the motor-generator 3 at a motor-generator end of the gearbox. The motor-generator 3 is secured to the housing of gearbox 16 with fasteners such as bolts (not illustrated). A rotor shaft 18 of the motor-generator 3 engages a corresponding central bore of the adjacent co-axially-located gear of the reduction gears 4 to permit transfer of torque between the motor-generator 3 and the reduction gears 4.

(35) At the crankshaft end of the gearbox 16, the reduction gear 4 which is co-axially-aligned with the clutch-pulley-damper unit 19 is coupled for co-rotation to pulley side of the clutch-pulley-damper unit 19, in this embodiment by bolts (not shown) passing through the co-axial reduction gear 4. The engine-side portion of the coupling (the portion having the crankshaft damper 6) is configured to be coupled to the front end of the engine crankshaft by fasteners or other suitable connections that ensure co-rotation of the engine-side portion 6 with the crankshaft. As described further below, the gearbox 16 is separately mounted to a structure that maintains the clutch-pulley-damper unit 19 co-axially aligned with the front end of the engine crankshaft.

(36) The cross-section view in FIG. 2B is a view from above the FEMG front end hardware, and the oblique cross-section view in FIG. 2C is a view at the crankshaft end of the gearbox 16. In this embodiment, the gearbox, motor-generator and clutch-pulley-damper unit assembly is arranged with the motor-generator 3 being located on the left side of the engine crankshaft and on the front side of the gearbox 16 (the side away from the front of the engine), where the motor-generator 3 may be located either in a space below or directly behind the vehicle's engine coolant radiator 20. Alternatively, in order to accommodate different vehicle arrangements the gearbox 16 may be mounted with the motor-generator 3 to the rear of the gearbox 16, preferably in a space laterally to the left side of the engine crankshaft (for example, adjacent to the oil pan at the bottom of the engine). The gearbox 16 further may be provided with dual-sided motor-generator mounting features, such that a common gearbox design may be used both in vehicle applications with a front-mounted motor-generator and vehicle applications with the motor-generator mounted to the rear side of the gearbox.

FEMG Clutch-Pulley-Damper Unit Embodiments

(37) FIGS. 3A-3C are views of the components of the clutch-pulley-damper unit 19 of FIGS. 2A-2C. When assembled, the unit is unusually narrow in the axial direction due to the substantial axial overlapping of the pulley 5, engine-side portion 6 (hereafter, damper 6) and clutch 15. In this embodiment the pulley 5 has two belt drive portions 21 configured to drive accessory drive belts (not illustrated), for example, one portion arranged to drive the engine cooling fan 7 surrounding the clutch 15, and another portion arranged to drive other engine accessories such as the air compressor 1. The drive belt portions 21 in this example concentrically surround the damper 6 and the clutch 15 (the belt drive portion 21 surrounding the damper 6 is omitted in FIGS. 2B and 2C for clarity).

(38) Within the clutch-pulley-damper unit 19 the clutch 15 includes two axially-engaging dog clutch elements 25, 26. As shown in the FIGS. 2A-2C cross-section views, the central core dog clutch element 25 is fixed for rotation with the damper 6, in this embodiment by bolts extending through axial bolt holes 28 from the FEMG gearbox side of the clutch-pulley-damper unit 19. The pulley 5 is rotationally supported on the central core element 25 by bearings 34.

(39) An engine-side portion of the outer circumference of the central core dog clutch element 25 includes external splines 29 arranged to engage corresponding internal splines 30 at an inner circumference of the axially-movable dog clutch element 26. The external splines 29 and internal splines 30 are in constant engagement, such that the movable dog clutch element 26 rotates with the damper 6 while being movable axially along the damper rotation axis.

(40) The movable dog clutch element 26 is also provided with axially forward-facing dogs 31 distributed circumferentially about the gearbox side of the element 26 (the side facing away from the engine). These dogs 31 are configured to engage spaces between corresponding dogs 32 on an engine-facing side of the pulley 5, as shown in FIG. 3C. The movable dog clutch element 26 is biased in the clutch-pulley-damper unit in an engaged position by a spring 33 located between the damper 6 and the movable dog clutch element 26, as shown in FIG. 2A. FIGS. 2B and 2C show the clutch disengaged position, in which the spring 33 is compressed as the movable dog clutch element 26 is axially displaced toward the damper 6.

(41) In this embodiment a clutch throw-out rod 27 is located concentrically within the central core dog clutch element 25. The engine-side end of the throw-out rod 27 is arranged to apply an axial clutch disengagement force that overcomes the bias of spring 33 to axially displace the dog clutch element 26 toward the damper 6, thereby disengaging its forward-facing dogs 31 from the corresponding dogs 32 at the engine-facing side of the pulley 5. In this embodiment, the gearbox end of the clutch throw-out rod 27 is provided with a bushing 303 and a bearing 304 which enables the bushing to remain stationary while the throw-out rod 27 rotates.

(42) The clutch throw-out rod 27 is axially displaced to disengage and engage the dog clutch 15 by a clutch actuator 22. In this embodiment the clutch actuator 22 is pneumatically-actuated, with compressed air entering fitting 305 over clutch actuator diaphragm 41 and thereby urging the center portion of the diaphragm 41 into contact with the throw-out rod bushing 303 to axially displace the clutch throw-out rod 27 toward the engine to disengage the clutch 15. When compressed air pressure is removed from the clutch actuator the diaphragm 41 retracts away from the engine, allowing the biasing spring 33 to axially displace the throw-out rod 27 and the dog clutch element 26 toward the pulley 5 to reengage the clutch dogs 31, 32 so that the pulley 5 co-rotates with the damper 6.

(43) FIG. 4 shows an alternative embodiment of the clutch-pulley-damper unit 19 in which the clutch 15 is a so-called wet multi-plate clutch. The wet multi-plate clutch includes friction and driven plates 23 splined in an alternating manner to an inner circumference of the pulley 5 and an outer circumference of a center portion of the damper 6. The clutch plates 23 are axially biased in compression by springs 24 between the damper 6 and the clutch actuator 22 (in this embodiment a pneumatically-actuated clutch actuation piston). The biasing of the stack of friction and driven plates together by the springs 24 engages the clutch 15 and causes pulley 5 and damper 6 to co-rotate with one another about the rotational axis of the engine crankshaft. When hydraulic pressure is applied to the clutch actuator 22 (on the FEMG gearbox side of the actuator), the springs 24 are compressed, allowing the alternating clutch friction and driven plates 23 to axially separate and thereby place the clutch 15 in a disengaged state, i.e., a state in which pulley 5 and damper 6 rotate independently.

(44) In this embodiment the hydraulic pressure is supplied by oil that is also used to cool and lubricate the gearbox reduction gears and their associated bearings, and cool the wet-multi-plate clutch's friction and driven plates. The application of the hydraulic pressure is controlled by a solenoid valve (not illustrated) in response to commands from the FEMG electronic control unit 13. The clutch 15 is sized to ensure the large amount of torque that can pass between the engine crankshaft and the motor-generator will be accommodated by the clutch without slippage. To this end, due to the axially-overlapping arrangement of the clutch-pulley-damper unit 19, the unit's cooling design should be configured to ensure adequate cooling of the clutch plates during all operations. While in this embodiment cooling is provided by the oil being circulated in the gearbox, other forced or passive cooling arrangements may be provided as long as the expected clutch temperature is maintained below the clutch's operating temperature limit.

FEMG Gearbox Embodiment

(45) FIG. 5 is a cross-section detailed view of a bearing arrangement at the crankshaft end of an embodiment of the FEMG gearbox 16. FIGS. 6A-6C and 7 show oblique views of this gearbox embodiment, in which a pair of gearbox clamshell-housing plates 35 enclose reduction gears 4, including a pulley-end gear 36, an idler gear 37 and a motor-generator-end gear 38.

(46) In this application, the gears have a drive ratio of 2:1, although any gear ratio which fits within the available space of a particular engine application while providing a desired ratio of crankshaft speed-to-motor-generator speed may be provided. The gears 36-38 may be spur gears, helical gears or have other gear teeth (such as double-helix herringbone gear teeth) as desired to suit the requirements of the particular FEMG system application. Such requirements include gear noise limitations needed to meet government noise emission or driver comfort limitations that might be met with helical gears, mechanical strength limitations, such as tooth stress limits, or axial thrust limits that might be meet with double-helix herringbone gear teeth which generate equal and opposite axial thrust components.

(47) The gearbox housing rotatably supports each of reduction gears 36-38 with bearings 39. The pulley-end gear 36 includes a plurality of through-holes 40 in a circumferential ring inside its gear teeth corresponding to holes on the front face of the pulley 5 of the clutch-pulley-damper. These holes receive fasteners configured to rotationally fix the pulley-end reduction gear 36 to the pulley 5 for co-rotation when driven by the crankshaft and/or by the motor-generator.

(48) The center of the pulley-end reduction gear 36 has a center aperture through which a pneumatically-powered dog-clutch actuating diaphragm 41 is located on a front face of the gearbox housing. The pneumatic diaphragm 41 axially extends and retracts a piston (not illustrated) arranged to engage the cup 27 on dog clutch element 26 to control engagement and disengagement of the clutch 15 of the clutch-pulley-damper unit 19. The diaphragm 41 is shown in FIG. 5 as covered by the pneumatic clutch actuator 22, while FIGS. 7-8 show a simpler, slim diaphragm cover 42 with a compressed air connection on its face that is suitable for use in particularly space-constrained FEMG applications. Regardless of the diaphragm cover design, the diaphragm 41 is acted on by compressed air in the chamber above the front face of the diaphragm created when the clutch actuator 22 or the cover plate 42 are installed over the diaphragm aperture at the front face of the gearbox housing. The admission and release of compressed air may controlled by solenoid valves (not illustrated) in response to commands from the FEMG control module 13. While the clutch actuation mechanism in this embodiment is a pneumatically-actuated diaphragm, the present invention is not limited to a particular clutch actuator. For example, an electro-mechanical actuator may be used, such as an electrically-powered solenoid configured to extend an actuator rod to disengage the clutch components.

(49) FIGS. 5 and 8 provide further detail of the mounting of this embodiment's pneumatic diaphragm actuator. In this embodiment an engine-side of a diaphragm mounting ring 45 is configured both to support the front-side bearing 39 associated with pulley-end reduction gear 36, and to receive on its front side the diaphragm 41. The bearing 39 may be retained and axially supported by any suitable device, such as a snap ring, or as shown in FIG. 5 by a nut 46. Once the mounting ring is secured in the illustrated large aperture on the front face of the gearbox housing clamshell plate 35, the pulley-end reduction gear 36 and its bearing 39, as well as the diaphragm 41, are axially fixed relative to the housing of gearbox 16.

(50) At the motor-generator end of the gearbox 16, a shaft hole 43 aligned with the rotation axis of the motor-generator-end reduction gear 38 is provided in at least one of the housing clamshell plates 35, as shown in FIGS. 6A-6C and 7. The shaft hole 43 is sized to permit the rotor shaft of the motor-generator 3 (not illustrated in this figure) to enter the gearbox 16 and engage motor-generator-end gear 38 for co-rotation.

(51) The FEMG gearbox may be cooled and lubricated by oil. The oil may be stored in a self-contained oil sump, or alternatively in a remote location, such as an external container or the engine's oil reservoir if the engine and gearbox are sharing the same oil source. The oil may be circulated throughout the gearbox by the motion of the gears or by a pump that distributes pressurized oil, such as an electric pump or a mechanical pump driven by the rotation of the reduction gears, and in addition to lubricating and cooling the gears may cool the clutch plates of a wet-clutch. Further, the gearbox may be provided with an accumulator that ensures a reserve volume of pressurized oil remains available to, for example, actuate the clutch of the clutch-pulley-damper unit when pump-generated pressure is not immediately available. In such an embodiment, a solenoid valve controlled by the FEMG control module could be used to release the pressurized oil to operate the actuator of the hydraulic clutch.

(52) FIG. 9 shows an example of a commercially-available gearbox showing an alternative motor-generator mounting arrangement in which a motor-generator mounting flange 44 provides the ability to mount the motor-generator to the gearbox with fasteners without the need for fastener penetrations into the gearbox housing.

(53) In the foregoing embodiments the end reduction gears 36, 38 are in constant-mesh engagement via idler gear 37. However, the present invention is not limited to this type of single reduction parallel shaft gearbox. Rather, other torque power transmission arrangements are possible, such as chain or belt drives, or drives with components such as torque transfer shafts aligned at an angle to the switchable coupling's rotation axis (for example, a worm-gear drive with a transfer shaft rotating on an axis perpendicular to the switchable coupling's rotation axis), as long as they can withstand the torque to be transferred without needing to be so large that the axial depth of the gearbox becomes unacceptably large. Such alternative gearbox arrangements may also be used in embodiments in which the motor-generator 3 is not aligned parallel to the rotation axis of the switchable coupling, but instead is positioned on the gearbox 16 and aligned as necessary to facilitate installation in regions of limited space (for example, motor-generator being attached at the end of the gearbox with its rotation axis aligned with a gearbox torque transfer shaft that is not parallel to the switchable coupling's rotation axis).

(54) Nor is the present invention limited to fixed reduction ratio constant-mesh arrangements, as other arrangements may be used, such as variable diameter pulleys (similar to those used in some vehicle constant velocity transmissions) or internally-disengageable gears, as long as the axial depth of the gearbox does not preclude the location of the FEMG system components in the region in front of the engine.

(55) In a preferred embodiment, the reduction ratio of the FEMG gearbox reduction gears 36-38 is 2:1, a ratio selected to better match crankshaft rotation speeds to an efficient operating speed range of the motor-generator 3.

FEMG System Hardware Mounting Embodiments

(56) As noted above, the FEMG assembly is preferably positioned such that the motor-generator 3 is located in a region of the engine compartment that is offset below and to a lateral side of the vehicle chassis rails supporting the engine. FIG. 10 illustrates such an arrangement, viewed from the front of the vehicle toward the rear. This figure shows the relationships in this embodiment between the motor-generator 3 and engine 8's crankshaft 47 (located axially behind the gearbox 16), oil pan 48, longitudinal chassis rails 49 and transverse engine mount 50.

(57) In the above FEMG arrangements the crankshaft 47, clutch-pulley-damper unit 19 and engine-end reduction gear 36 are located on the same rotation axis. In order to ensure this relationship is maintained, the FEMG gearbox should be located in front of the engine in a manner that ensures there is no relative movement between the engine and the gearbox, either transverse to the rotation axis of the crankshaft or around the crankshaft axis.

(58) While it would be possible to mount the FEMG gearbox in a manner that does not directly connect the gearbox to the engine (for example, by suspending the FEMG gearbox from a bracket connected to the chassis rails holding the engine), it is preferable to directly couple the gearbox to either an adjacent vehicle frame member or to the engine block. Examples of FEMG gearbox-to-engine mounting bracket and corresponding arrangement of mounting holes in the gearbox is shown in FIGS. 10-14.

(59) In FIG. 10, the FEMG gearbox 16 is secured against rotation or transverse motion relative to the engine 8 by fasteners 306 to directly to the engine 8. FIG. 11 shows an alternative approach in which a torque arm 307 (aka tie-rod) is attached at one end to an anchor point 308 of the FEMG gearbox 16, and at the opposite end to the adjacent frame rail 49, thereby providing non-rotation support of the gearbox 16.

(60) A further alternative FEMG mounting approach is shown in FIG. 12. In this embodiment a mounting bracket 51 is provided with bolt holes 52 arranged around the bracket to align with corresponding holes in the engine block 8 which receive fasteners to provide an engine-centric fixed support for the FEMG gearbox. In this example, the flat bottom of the mounting bracket 51 is arranged to be positioned on top of elastomeric engine mounts, as are often used in commercial vehicle engine installations. The engine-side portion of the mounting bracket 51 is a portion of a bracket that must extend under and/or around the clutch-pulley damper unit to reach an FEMG gearbox mounting bracket portion to which the gearbox may be coupled, while ensuring there is sufficient clearance available within the bracket to allow the clutch-pulley-damper unit to rotate therein.

(61) FIGS. 13 and 14 schematically illustrate the location of an FEMG gearbox 16 on a such a bracket and the corresponding distribution of fastener holes around the FEMG reduction gear 36 and the FEMG-side of the mounting bracket 51. FIGS. 13 and 14 both show circumferential arrangement of the corresponding fastener holes 53 on the FEMG gearbox 16 and on the FEMG gearbox-side of the FEMG mounting bracket 51. In FIG. 14, the engine-side portion and the FEMG gearbox-side portion of the mounting bracket 51 are linked by arms 54 extending parallel to the engine crankshaft axis in spaces clear of the rotating clutch-pulley-damper unit 19 (not illustrated in these figures for clarity). The schematically-illustrated arms 54 are intended to convey the mounting bracket arrangement concept, with the understanding that the connection between the engine-side and FEMG gearbox-side of the mounting bracket may be any configuration which links the front and rear sides of the bracket in a manner that secures the FEMG gearbox against motion relative to the engine crankshaft. For example, the arms 54 may be rods welded or bolted to the front and/or rear sides of the bracket, or the arms may be portions of an integrally-cast part that extends around the clutch-pulley-damper unit 19. Preferably, the mounting bracket 51 is designed such that its FEMG gearbox-side portion has a fastener hole pattern that facilitates rotation of the FEMG gearbox relative to the bracket (clocking) as needed to index the gearbox at various angles to adapt the FEMG components to various engine configurations, for example in retrofitting an FEMG system to a variety of existing vehicle or stationary engine applications.

FEMG System Motor-Generator and Electronic Controls Embodiments

(62) An example of a motor-generator which is suitable for attachment to the motor-generator end of an FEMG gearbox is shown in FIG. 15. In this embodiment an FEMG gearbox-side 55 of the motor-generator 3 includes a plurality of studs 56 configured to engage corresponding holes in a mounting flange on the gearbox, such as the mounting flange 44 shown on the exemplary gearbox 16 in FIG. 9. In order to transfer torque between the rotor of the motor-generator 3 and the motor-generator-end reduction gear 38, a rotor bore 57 receives a shaft (not illustrated) extending into a corresponding bore in reduction gear 38. The shaft between the reduction gear 38 and the rotor of the motor-generator 3 may be a separate component, or may be integrally formed with either the rotor or the reduction gear. The shaft also may pressed into one or both of the rotor and the reduction gear, or may be readily separable by use of a displaceable connection, such as axial splines or a threaded connection.

(63) The motor-generator 3 in this embodiment also houses several of the electronic components of the FEMG system, discussed further below, as well as low-voltage connections 58 and high voltage connection 59 which serve as the electrical interfaces between the motor-generator 3 and the control and energy storage components of the FEMG system.

(64) Preferably the motor-generator 3 is sized to provide at least engine start, hybrid electrical power generation and engine accessory drive capabilities. In one embodiment, a motor generator having a size on the order of 220 mm in diameter and 180 mm in longitudinal depth would, as shown in the graph of FIG. 16, provide approximately 300 Nm of torque at zero rpm for engine starting, and up to approximately 100 Nm near 4000 rpm for operating engine accessories and/or providing supplemental torque to the engine crankshaft to assist in propelling the vehicle. With a 2:1 reduction ratio of the FEMG gearbox, this motor-generator speed range is well-matched to a typical commercial vehicle engine's speed range of zero to approximately 2000 rpm.

(65) The FEMG motor-generator design is constrained by thermal, mechanical and electrical considerations. For example, while temperature rise of the motor generator during starting is relatively limited by the relatively short duration of the starting operation, when the motor-generator alone is driving one or more demanding engine accessories such as the engine cooling fan, the required torque output from the motor can be in the range of 50 Nm to 100 Nm. In the absence of adequate motor-generator cooling the temperature rise during sustained high-torque output conditions could be significant. For example, at current density J in the motor-generator windings of 15 A/mm.sup.2, an adiabatic temperature rise could be on the order of 30 C. For this reason, it is preferred that the FEMG motor-generator be provided with forced cooling such as the example shown in FIG. 17 in which engine coolant or cooling oil (such as oil from the gearbox oil circuit) circulates through a cooling fluid passage 60 in the motor-generator. It is particularly preferable that a portion 61 of the cooling passage 60 is also routed to provide cooling to the FEMG system electronic components mounted on the motor-generator 3.

(66) The type of electric machine selected may also introduce limitations or provide specific advantages. For example, in an induction-type electric motor, the breakdown torque may be increased 10-20% using an inverter (with a corresponding increase in flux), and the breakdown torque is typically high, e.g., 2-3 times the machine's rating. On the other hand, if a permanent magnet-type machine is selected, excessive stator excitement current must be avoided to minimize the potential for demagnetization of the permanent magnets. While physical arrangement and operating temperature can influence the point at which demagnetization is problematic, typically current values greater than two times the rated current must be experienced before significant demagnification is noted.

(67) With such factors in mind, a preferred embodiment of the motor-generator 3 would have the capability of operating at 150% of its nominal operating range. For example, the motor-generator may have a rated speed of 4000 rpm, with a 6000 rpm maximum speed rating (corresponding to a maximum engine speed of 3000 rpm) and a capacity on the order of 60 KW at 4000 rpm. Such a motor-generator, operating at a nominal voltage of 400 V, would be expected to provide a continuous torque output of approximately 100 Nm, an engine cranking torque of 150 Nm for a short duration such as 20 seconds, and a peak starting torque at zero rpm of 300 Nm.

(68) The FEMG motor-generator 3, as well as the other components of the FEMG system, in this embodiment are controlled by the central FEMG control module 13, an electronic controller (ECU). With respect to the motor-generator, the FEMG control module: (i) controls the operating mode of the motor-generator, including a torque output mode in which the motor-generator outputs torque to be transferred to the engine accessories and/or the engine crankshaft via the clutch-pulley-damper unit, a generating mode in which the motor-generator generates electrical energy for storage, an idle mode in which the motor-generator generates neither torque or electrical energy, and a shutdown mode in which the speed of the motor-generator is set to zero (a mode made possible when there is no engine accessory operating demand and the clutch of the clutch-pulley-damper unit is disengaged); and (ii) controls the engagement stated of the clutch-pulley-damper unit (via components such as solenoid valves and/or relays as required by the type of clutch actuator being employed).

(69) The FEMG control module 13 controls the motor-generator 3 and the clutch-pulley-damper unit 19 based on a variety of sensor inputs and predetermined operating criteria, as discussed further below, such as the state of charge of the energy store 11, the temperature level of the high voltage battery pack within the energy store, and the present or anticipated torque demand on the motor-generator 3 (for example, the torque required to achieve desired engine accessory rotation speeds to obtain desired levels of engine accessory operating efficiency). The FEMG control module 13 also monitors motor-generator- and engine crankshaft-related speed signals to minimize the potential for damaging the clutch components by ensuring the crankshaft-side and pulley-side portions of the clutch are speed-matched before signaling the clutch actuator to engage the clutch.

(70) The FEMG control module 13 communicates using digital and/or analog signals with other vehicle electronic modules, both to obtain data used in its motor-generator and clutch-pulley-damper control algorithms, and to cooperate with other vehicle controllers to determine the optimum combination of overall system operations. In one embodiment, for example, the FEMG control module 13 is configured to receive from a brake controller a signal to operate the motor-generator in generating mode to provide regenerative braking in lieu of applying the vehicle's mechanical brakes in response to a relatively low braking demand from the driver. The FEMG control module 13 is programmed to, upon receipt of such a signal, evaluate the current vehicle operating state and provide the brake controller with a signal indicating that regenerative braking is being initiated, or alternatively that electrical energy generation is not desirable and the brake controller should command actuation of the vehicle's mechanical brakes or retarder.

(71) FIG. 18 provides an example of the integration of electronic controls in an FEMG system. In this embodiment the FEMG control module 13 receives and outputs signals, communicating bi-directionally over the vehicle's CAN bus with sensors, actuators and other vehicle controllers. In this example the FEMG control module 13 communicates with the battery management system 12 which monitors the state of charge of the energy store 11 and other related energy management parameters, with an engine control unit 63 which monitors engine sensors and controls operation of the internal combustion engine, and with the FEMG system's electrical energy management components, including the power inverter 14 which handles AC/DC conversion between the AC motor-generator 3 and the DC portion of the electrical bus between the vehicle's DC energy storage and electrical consumers (not illustrated in this figure). The FEMG control module 13 further communicates with the vehicle's DC-DC converter 10 which manages the distribution of electrical energy at voltages suitable for the consuming device, for example, conversion of 400 V power from the energy store 11 to 12 V required by the vehicle's 12 V battery 9 and the vehicle's various 12 V equipment, such as lighting, radio, power seats, etc.

(72) FIG. 18 also illustrates the communication of data as inputs into the FEMG system control algorithms from sensors 64 associated with the motor-generator 3, the clutch-pulley-damper unit 19's clutch, the various engine accessories 1 and the 12 V battery 9 (for example, a motor-generator clutch position sensor 101, a motor-generator speed sensor 102, engine accessory clutch positions 103, air compressor state sensors 104, dynamic heat generator state sensors 105, an FEMG coolant temperature sensor 106, an FEMG coolant pressure sensor 107, and a 12 V battery voltage sensor 108).

(73) Many of the signals the FEMG control module 13 receives and exchanges are transmitted over the vehicle's SAE J1939 standard-compliant communications and diagnostic bus 65 to/from other vehicle equipment 66 (for example, brake controller 111, retarder controller 112, electronic air control (EAC) controller 113, transmission controller 114, and dashboard controller 115). Examples of the types of sensor and operational signals and variables exchanged, and their respective sources, are provided in Table 1.

(74) TABLE-US-00001 TABLE 1 Signals/Variables to monitor Source of the signal High voltage battery: Coming from the Battery Management System state of charge (SOC) BMS High voltage battery: Coming from the BMS temperature Vehicle speed J1939 message: Wheel-Based Vehicle Speed Engine torque J1939 message: Driver's Demand Engine-Percent Torque Engine speed J1939 message: Engine Speed Brake application J1939 message: Brake Application Pressure High status Range. Each axle Cooling fan clutch J1939 message: Requested Percent Fan Speed A/C compressor J1939 message: Cab A/C Refrigerant Compressor clutch Outlet Pressure Air compressor clutch J1939 message: Intelligent Air Governor (IAG) Neutral Gear J1939 message: Transmission Current Gear Transmission Clutch J1939 message: Transmission Clutch Actuator Door open J1939 message: Open Status of Door 1/Open Status of Door 2 Temperature of the J1939 message: Cab Interior Temperature cabin Air brake system J1939 message: Brake Primary Pressure pressure FEMG coolant Temperature sensor mounted inside the gearbox. temperature Engine oil J1939 message: Engine Oil Temperature 2 temperature Engine coolant J1939: Engine Coolant Temperature temperature Intake manifold J1939 message: Engine Intake Manifold 1 Air temperature Temperature (High Resolution) MG rotating speed Encoder mounted on the Gearbox or the MG

(75) Outputs from the FEMG control module 13 include commands to control the generation of electrical energy or torque output from the motor-generator 3, commands for engaging and disengaging of the clutch of the clutch-pulley-damper unit 19, commands for engaging and disengaging the clutches 120 of individual engine accessories 1 (discussed further below), and commands for operation of an FEMG coolant pump 121.

FEMG Control Module System Control of FEMG System Components

(76) In addition to controlling the motor-generator and its clutched connection to the engine crankshaft, in this embodiment the FEMG control module has the ability to control the engagement state of any or all of the individual clutches connecting engine accessories to the accessory drive belt driven by pulley 5, thereby permitting the FEMG control module to selectively connect and disconnect different engine accessories (such as the air conditioner compressor 2 or the vehicle's compressed air compressor 1) to the accessory drive according to the vehicle's operating state. For example, when operating conditions permit, the FEMG control module's algorithms may prioritize electrical energy generation and determine that some of the engine accessories need not operate. Alternatively, the FEMG control module is programmed to operate an engine accessory in response to a priority situation which requires operation of the accessory, even if doing so would not result in high overall vehicle operating efficiency. An example of the latter would be receipt of a compressed air storage tank low pressure signal, necessitating engagement of the air compressor's clutch and operation of the pulley 5 at a high enough speed to ensure sufficient compressed air is stored to meet the vehicle's safety needs (e.g., sufficient compressed air for pneumatic brake operation). Another example would be commanding the motor-generator and the engine cooling fan clutch to operate the engine cooling fan at a speed high enough to ensure adequate engine cooling to prevent engine damage.

(77) Preferably, the FEMG control module is provided with engine accessory operating performance data, for example in the form of stored look-up tables. With engine accessory operating efficiency information, the ability to variably control the operating speed of the motor-generator to virtually any desired speed when the clutch-pulley-damper unit clutch is disengaged, and knowledge of the vehicle's operating state received from sensors and the vehicle's communications network, the FEMG control module 13 is programmed to determine and command a preferred motor-generator speed and a combination of engine accessory clutch engagement states that results in a high level of overall vehicle system efficiency for the given operating conditions.

(78) While overall system efficiency may be improved by the presence of a large number of individual engine accessory clutches (including on/off, multi-stage or variable-slip clutches), even in the absence of individual accessory clutches the FEMG control module 13 may use engine accessory performance information to determine a preferred motor-generator operating speed that causes the pulley 5 to rotate at a speed that satisfies the current system priority, whether that priority is enhancing system efficiency, ensuring the heaviest engine accessory demand is met, or another priority such as starting to charge the energy store 11 at a predetermined time sufficiently before an anticipated event to ensure sufficient electrical energy is stored before the vehicle is stopped. For example, the FEMG control module in this embodiment is programmed to determine the current state of charge of the energy storage 11 and the amount of time available before an anticipated driver rest period, and initiate motor-generator charging of the energy store 11 at a rate that will result in enough energy being present at engine-shut-off to support vehicle system operation (such as sleeper compartment air conditioning) over the anticipated duration of the reset period (e.g., an 8-hour overnight rest period).

(79) A similar rationale applies regardless of the number individual engine accessory clutches present, i.e., the FEMG control module may be programmed to operate the motor-generator 3 and the clutch-pulley-damper unit clutch 15 in a manner that meets the priorities established in the algorithms, regardless of whether a few, many or no individual engine accessory clutches are present. Similarly, a variety of prioritization schemes may be programmed into the FEMG control module to suit the particular vehicle application. For example, in a preferred embodiment, an energy efficiency priority algorithm may go beyond a simple analysis of what configuration of pulley speed and individual engine accessory clutch engagement provides an optimum operating efficiency for the highest priority engine accessory, but may also determine whether the operation of a combination of engine accessories at a compromise pulley speed will result in a greater overall system efficiency while still meeting the priority accessory's demand, i.e., operating each of the individual engine accessories at speeds that are offset from their respective maximum efficiency operating points if there is a pulley speed which maximizes overall vehicle efficiency while still meeting the vehicle system demands.

FEMG Electric Energy Generation, Storage and Voltage Conversion Embodiments

(80) The relationship between the power electronics and current distribution in the present embodiment is shown in greater detail in FIG. 19. The three phases of the alternating current motor-generator 3 are connected to the AD/DC power inverter 14 via high voltage connections. Electrical energy generated by the motor-generator 3 is converted to high voltage DC current to be distributed on a DC bus network 67. Conversely, DC current may be supplied to the bi-directional power invertor 14 for conversion to AC current to drive the motor-generator 3 as a torque-generating electric motor.

(81) A known embodiment of a bi-directional AC/DC power inverter such as inverter 14 as shown in FIG. 20. This arrangement includes a six IGBT power transistor configuration, with switching signals provided from a controller (such as from the FEMG control module 13) to control lines 68A-68F based on a vector control strategy. Preferably, the control module for the power inverter 14 is located no more than 15 cm away from the power inverter's IGBT board. If desired to minimize electrical noise on the DC bus 67, a filter 69 may be inserted between the power inverter and the rest of the DC bus.

(82) FIG. 19 also shows two primary DC bus connections, the high voltage lines between the power inverter 14 and the energy store 11. The bi-directional arrows in this figure indicate that DC current may pass from the power inverter 14 to the energy store 11 to increase its state of charge, or may flow from the energy store to the DC bus 67 for distribution to the power invertor 14 to drive the motor-generator 3 or to other DC voltage consumers connected to the DC bus. In this embodiment, a DC/DC voltage converter 70 is provided between the DC bus and the energy store 11 to adapt the DC voltage on the DC bus generated by the motor-generator 3 to the preferred operating voltage of the energy store. FIG. 19 also shows that the DC bus 67 also may be connected to an appropriate voltage converter, such as AC-DC voltage converter 309 that converts electric energy from an off-vehicle power source 310, such as a stationary charging station, to the voltage on DC bus 67 to permit charging of the energy store independent from the motor-generator 3 when the vehicle is parked.

(83) In addition to the bi-directional flow of DC current to and from the energy store 11, the DC bus 67 supplies high voltage DC current to vehicle electrical consumers, such as vehicle lights, radios and other typically 12 V-powered devices, as well as to 120 V AC current devices such as a driver sleeper compartment air conditioner and/or a refrigerator or cooking surface. In both cases an appropriate voltage converter is provided to convert the high voltage on the DC bus 67 to the appropriate DC or AC current at the appropriate voltage. In the embodiment shown in FIG. 19, a DC/DC converter 71 converts DC current at a nominal voltage on the order of 400 V to 12 V DC current to charge one or more conventional 12 V batteries 72. The vehicle's usual 12 V loads 73 thus are provided with the required amount of 12 V power as needed, without the need to equip the engine with a separate engine-driven 12 V alternator, further saving weight and cost while increasing overall vehicle efficiency. FIG. 21 illustrates a known embodiment of a forward DC/DC converter such as DC/DC converter 71, in which the FEMG control module 13 controls the conversion of high DC voltage from the DC bus 67 to the 12 V output 75 of the convertor by providing FEMG control signals to a transistor drive circuit 74 to manage the flow of current through the primary winding 76 of the DC/DC converter's transformer 77.

(84) The bi-directional high voltage DC/DC converter 70 is a so-called buck plus boost type of voltage converter, such as the known electrical arrangement as shown in FIG. 22. FIG. 23 shows how, when the electronically controlled switch S in FIG. 22 is actuated, an input voltage V.sub.in drives in a pulsed manner a corresponding current oscillation across the inductor L and capacitance C, resulting in a continuous output voltage v.sub.o, oscillating smoothly about a baseline voltage <v.sub.o>.

(85) The desire to keep short the distance between the power invertor 14 and the motor-generator's three AC phase lines may be satisfied by integrating several electronic components into the housing of a motor-generator, as shown in FIG. 24. On the side of the motor-generator opposite the side which would face the gearbox 16, wires for the three AC phases 78A-78C emerge and are connected to a high voltage portion 79 of a circuit board 84 (in FIG. 24 the portion of the circuit board 84 to the left of the dashed line). To the right of the AC phase connections the power inverter is integrated into the circuit board 84, with the IGBT pack 80 being located under the IGBT driver circuits 81.

(86) Also co-located on the circuit board 84 is a section 82 containing electrical noise-suppressing electromagnetic interference (EMI) filter and DC power capacitors, as well as embedded micro controllers 83 of the FEMG ECU. The dashed line represents an electrical isolation 85 of the high voltage portion 79 from the low-voltage portion 86 which communicates with the rest of the FEMG system and vehicle components via electrical connectors 58. The high voltage and high current either generated by the motor-generator 3 or received by the motor-generator 3 from the energy store 11 passes from the high voltage portion 79 of the circuit board 84 to the high voltage connection 59 via circuit paths (not illustrated) behind the outer surface of the circuit board.

(87) Among the advantages of this high degree of motor-generator and power electronics integration are simplified and lower cost installation, minimizing of electrical losses over longer-distance connections between the motor-generator and the power electronics, and the ability to provide cooling to the power electronics from the motor-generator's already-present forced cooling without the need for additional dedicated electronics cooling arrangements.

FEMG System Energy Store and Battery Management Controller Embodiment

(88) The storage cells used in the energy store 11 in this embodiment are Lithium-chemistry based, specifically Li-Ion batteries. Li-Ion has several advantages over conventional battery chemistries such as Lead-acid, including lighter weight, better tolerance of fast-charging charge rates, high power density, high energy storage and return efficiency, and long cycling life.

(89) The energy store 11 is sized to be able to receive and supply very large current flow from/to the motor-generator 3, as a crankshaft-driven motor-generator can generate kilowatts of electrical power, and an energy-store-powered motor-generator can require 300 peak amperes of high voltage current to start a diesel engine, in addition to requiring enough high voltage current to generate upwards of 100 Nm of torque to drive engine accessories when the clutch-pulley-damper unit is disengaged from the engine crankshaft.

(90) While the super capacitors are capable of handling the peak current demands of the FEMG system, the battery portion of the energy store 11 is sized to be able to provide sustained current discharge rates and total energy output to meet the most demanding current demand. Based on experience with commercial vehicle operation, the battery portion of the energy store 11 in this embodiment is sized to ensure satisfactory operation at the equivalent of 58 KW for ten minutes each hour (a power demand corresponding to operation of the engine cooling fan at its maximum speed solely by the motor-generator at regular intervals, as well as concurrent air conditioning and air compressor use). Calculations have shown that a discharge of 58 KW for 10 minutes per hour, assuming an operating efficiency of the power inverter 14 of 95%, would require withdrawal of 10 KWh (kilowatt-hours) of energy from the energy store 11. With a system voltage of 400 V, this amount of discharge requires the energy store batteries to have a storage capacity of approximately 15 Ah (ampere-hours).

(91) In addition to calculating the minimum battery capacity to meet the expected greatest vehicle demand, the design of the battery portion of the energy store 11 takes into account baseline operational needs. For example, there is an operational desire to not completely discharge the energy store batteries, both to avoid encountering a situation in which the energy store cannot meet an immediate vehicle need (such as not being able to start the engine when the motor-generator is operated as an engine starting device) and to avoid potential battery cell damage from discharge to levels well below the battery cell manufacturer's minimum recommended cell operating voltage (for a 3.8 V-4.2 V Lithium-based battery cell, typically not below 1.5-2 V/cell). The design of the present embodiment's energy store therefore includes the requirement that the greatest discharge demand not discharge the battery portion of the energy store below 50% capacity. This requirement results in energy store 11 having a battery capacity of 30 Ah.

(92) With a design target of 30 Ah and using Li-Ion battery cells each having an individual nominal voltage of 3.8 V and a discharge capacity of 33 Ah at a 0.3 C discharge rate (such a battery cell having a weight of 0.8 Kg (kilograms) and rectangular dimensions of 290 mm216 mm7.1 mm), it was determined that the desired energy store capacity (30 Ah at 400 V) could be provided by packaging 4 individual battery cells in series to produce a 33 Ah battery module having a nominal voltage of 15.2 V, and then connecting 28 of these battery modules in series to provide a battery pack with a 33 Ah capacity at a nominal voltage of 15.2 V/module28 modules=425 V (actual operating voltage typically at or below 400V). This battery pack has a weight (without housing) of approximately 90 Kg and a volume of approximately 50 liters, a weight and size readily accommodated alongside a chassis rail of a commercial vehicle.

(93) The energy store 11 is provided with a battery management system (BMS) 12. The BMS control module monitors the state of charge of the battery pack and temperatures, handles battery maintenance tasks such as cell balancing (the monitoring and adjusting of charge states of individual cells or groups of cells), and communicates battery pack status information to the FEMG control module 13. The battery management system 12 may be co-located with the FEMG control module 13 or at another location remote from the battery pack in energy store 11; however, installation of the battery management system 12 with the energy store 11 permits modular energy storage system deployment and replacement.

(94) Another design consideration with energy store 11 receiving and discharging large amounts of high voltage current is the need for cooling. In the present embodiment, among the FEMG components requiring cooling, the energy store 11, the motor-generator 3, the power inverter 14, the gearbox 16 and the clutch 15 of the clutch-pulley-damper unit 19, the battery store 11 has the greatest need for cooling to avoid damage from over-temperature conditions. The preferred temperature operating range of Li-Ion batteries is 20 C. to 55 C. These temperatures compare to operating temperature limits on the order of 150 C. for the motor-generator 3, 125 C. for the power invertor 14, and 130 C. for the gearbox 16 (as well as the clutch 15 if the clutch is an oil-bath wet clutch). In this embodiment, significant savings in complexity and cost are realized by having all of the primary FEMG components being cooled by the oil that is circulated in the gearbox for lubrication and cooling. This is possible if the energy store 11 battery pack receives the cooling oil as the first component downstream of the air/oil radiator which dissipates heat from the oil, i.e., before the cooled oil is recirculated and absorbs heat from other FEMG components in the oil cooling circuit. This arrangement ensures the battery pack receives the cooling oil flow at a temperature that allows the battery pack to remain below 55 C., prior to the oil encountering higher-temperatures in the motor-generator, power inverter and gearbox.

FEMG System Energy Store State of Charge Determination Algorithm Embodiments

(95) The state of charge of the energy store battery may be determined in a variety of ways. FIG. 25 is an example of a known battery management system state of charge estimation control algorithm usable in the present invention. In a first step S101 the battery management system 12 initializes at start-up (key on). Step S102 symbolizes the BMS's estimation of the state of charge of the battery cells by the so-called Coulomb counting method, here, by sampling cell and group voltages (V, T) and temperatures to establish an estimated baseline charge level, and from this an initial point tracking the amount of current introduced into the battery pack and withdrawn from the battery pack (I).

(96) However, while this approach to tracking state of charge has the advantage of providing real-time, very accurate current flow monitoring with relatively inexpensive technologies, it does not provide a reliable indication of the amount of charge lost from the battery cells due to the battery cell self-discharging phenomena resulting from undesired chemical reactions. Because this phenomena is strongly temperature dependent and may result in substantial charge loss not detected in step S102, in this embodiment the battery management system also executes an additional state of charge estimation step S103, a so-called prior in the loop approach. In this state of charge estimation approach, the open circuit voltage of the battery cells is measured and this voltage is compared to stored voltage/charge state values to provide an estimate of the battery charge level which inherently accounts for previous self-discharge losses. In addition, by comparison with previously stored information a rate of self-discharge may be estimated, and from this self-discharge rate a state of health of the battery may be estimated (i.e., a high self-discharge rate indicating that the health of the battery cells is degraded as compared to when new).

(97) A disadvantage of the prior in the loop approach is that it cannot be easily used in real time, as the energy store 11's battery pack is in use to receive and discharge high voltage current as needed to support ongoing vehicle operation. As a result, the open-voltage-based state of charge and state of health estimations in step S103 are only performed when the energy store's battery is in a state in which no current is being received by or discharged from the battery pack. If the step S103 estimations cannot be made, this battery management system routine proceeds to step S104, and the most recent step S103 estimates of battery state of charge and state of health are used in the subsequent calculations.

(98) Based on the cell and group voltages, temperatures, current input and outputs from step S102 and the most recent step S103 correction factors to account for self-discharge effects, in step S104 the battery management system calculates appropriate charging and discharging power limits available for operation of the energy store 11 within the FEMG system, and executes a cell balancing algorithm to identify battery cells requiring charge equalization and apply appropriate selective cell charging and/or discharging to equalize the cell voltages within the 4-cell modules and between the 28 modules. Cell balancing is of particular importance when Li-Ion battery cells are in use, as such cells can age and self-discharge at different rates from one another. As a result, over time the individual battery cells can develop different abilities to accept a charge, a condition that can result in one or more of the cells in a module (or between different modules) being overcharged and others undercharged. In either case, significantly over-or under-charged battery cells may be irreparably damaged.

(99) In step S105 the battery management system 12 communicates battery pack status information to the FEMG control module 13, including information on the power limits required for the current charge state and temperature of the battery cells. In parallel in step S106 battery cell data is stored in memory for use in future cell monitoring iterations. Upon completion of the battery pack status determination and cell balancing routines, control returns to the beginning of the charge estimation control loop, with self-discharge rate data being made available at the start of the loop for use in the subsequent steps.

FEMG System Operating Modes and Control Algorithm Embodiments

(100) In this embodiment, the FEMG system operates in several modes, including generator mode, motor mode, idle mode, off mode and stop/start mode. The mode selected for the current operating conditions is based at least in part on the current state of charge of the energy store 11, where the FEMG control module 13 is programmed to recognize based on data received from the battery management system 12 a minimum charge level, in this embodiment 20% of charge capacity, an intermediate charge level of 40%, and a maximum charge level of 80% (a level selected to ensure the energy store is protected against overcharging of cells, particularly in the event that individual cell self-discharge has created a cell imbalance condition).

(101) In the generator mode, the clutch 15 is engaged and the motor-generator 3 is driven to generate electrical energy for storage whenever the energy store state of charge is below the minimum charge level, and the clutch will stay engaged until the intermediate charge state level is reached. Once the intermediate charge state level is reached, the FEMG control module 13 switches between the generator, motor, idle and off modes as needed. For example, if the motor-generator 3 is being operated with the clutch 15 disengaged to drive the engine accessories, the FEMG control module commands a switch to generator mode and engage the clutch 15 to charge the energy store 11 when braking, deceleration or negative torque events occur (so long as the energy store 11 state of charge remains below the maximum charge state level).

(102) When in the motor mode with the clutch 15 disengaged, the FEMG control module 13 modulates the amplitude and frequency of the current being delivered by the inverter 14 to the motor-generator 3 in order to provide infinitely-variable speed control. This capability permits the motor-generator 3 to be operated in a manner that drives the pulley 5, and hence the engine accessories driven by the pulley 5, at a speed and torque output level that meets the demands of the current operating conditions without waste of energy due to operating at unnecessarily high speed and torque output levels. The FEMG system's variable output control over the motor-generator 3 has the additional benefit of minimizing the amount of stored electrical energy that must be delivered from the energy store 11, reducing energy store charging needs and extending the length of time the energy store 11 can supply high voltage current before reaching the minimum state of charge.

(103) If the level of charge in the energy store 11 is above the minimum level, there are no braking, deceleration, or negative torque conditions present, and the engine accessories are not demanding torque from the motor-generator 3, the FEMG control module 13 initiates the idle mode, in which the clutch 15 of the clutch-pulley-damper 19 is disengaged and the motor-generator turned off, i.e., not operated to either generate electrical energy for storage or generate torque for driving the engine accessories.

(104) In any of the generator, motor or off modes, the FEMG control module may command the clutch 15 be engaged if the engine requires torque output assistance from the motor-generator, and simultaneously command supply of electrical energy from the energy store 11 to the motor-generator to convert into supplemental torque to be transferred to the engine crankshaft.

(105) The FEMG control module is additionally programmed to protect against unintended over-discharge of the energy store 11. For example, in this embodiment when the torque and speed demand of engine cooling fan 7 is above 90% of its design maximum demand, the clutch 15 of the clutch-pulley-damper 19 is engaged to mechanically drive the engine cooling fan 7 (and as consequence also the other engaged engine accessories) from the engine crankshaft. This permits the motor-generator 3 to be operated in the idle or generator modes in order to avoid a potentially damaging deep discharge of the energy store 11, as well as avoiding a state of charge condition in which the stored energy is not sufficient to support engine-off loads (for example, engine starting or sleeper compartment support during engine-off rest periods).

(106) An additional operating mode is a starting mode, used for initially starting a cold engine and start-stop functionality (i.e., shut-down of the engine after a stop and re-start when travel is resumed). In this embodiment the start-stop function is controlled by the FEMG control module 13. When appropriate conditions exist (e.g., energy store 11 charge state above a minimum threshold for engine starting, vehicle speed of zero for a sufficient period, transmission in neutral or transmission clutch disengaged, vehicle doors closed, etc.), the FEMG control module signals the engine control module to shut down the engine, thereby minimizing fuel consumption and undesired engine idling noise. When the vehicle is to resume motion, as indicated by a signal such as release of the brake pedal or operation of the transmission clutch, the FEMG control module 13 commands engagement of clutch 15 and supply of energy from the energy store 11 to operate the motor-generator 3 to produce a large amount of torque for engine starting. The delivery of engine starting torque occurs from a motor-generator initial rotational speed of zero in the case whether there was no engine accessory operation demand during the engine-off period (in which case there would be no need for pulley-crankshaft speed matching, as both sides of the clutch would be at zero speed). Alternatively, if the motor-generator 3 had been driving pulley 5 to power engine accessories during the engine shut down period, the motor-generator 3 would be commanded to slow to below a rotational speed at when clutch damage would occur when the clutch 15 is engaged. In the case of a dog clutch, this may be at or near zero speed, whereas a wet multi-plate clutch could better tolerate some relative motion between the pulley-side and stationary crankshaft-side of the clutch.

(107) The FEMG system further can store sufficient energy to permit operation of a dynamic heat generator to pre-heat a cold engine prior to a cold start, significantly reducing the resistance a cold engine would present to the motor-generator during a cold start. The use of a dynamic heat generator also creates the opportunity to decrease the size, weight and cost of the motor-generator by reducing the peak cold-starting torque demand that the motor-generator much be designed to provide over the vehicle's expected operating conditions.

(108) The peak cold-starting torque demand that the motor-generator much be designed to provide over the vehicle's expected operating conditions also may be reduced by other assistance devices. For example, the size of the motor-generator may be reduced if engine starting torque is supplemented by a pneumatic starter motor powered by the vehicle's compressed air storage. The size of a pneumatic starter motor may be minimized to ensure that it can be located with the FEMG components at the front of the engine because the pneumatic starter motor need not be sized to be able to start the engine by itself. Such a cold-starting assist would be lower cost and lower weight than the option of retaining a conventional electric engine starter motor to rotate the engine flywheel, and would have negligible effect on the system energy efficiency improvements obtainable by the FEMG system.

FEMG System Engine Accessory Operating Speed and Motor-Generator Operating Speed Determination Algorithms

(109) An embodiment of an FEMG system control strategy is explained with the assistance of the flow charts of FIGS. 26 and 27, following a brief discussion of the underlying bases of the strategy.

(110) As a general matter, higher fuel savings may be obtained by maximizing the amount of time engine accessories and other components are electrically driven, rather than by the traditionally-provided engine mechanical power. A control strategy which improves electrical energy deployment is an essential part of obtaining these improvements. An approach of the present invention is to maximize the number of components that can be driven electrically while minimizing the number of electric machines required to drive the accessories. Thus, rather than providing most or all of the vehicle's power-demanding components with their own electric motors, in the present invention a single electric motor (such as motor-generator 3) provides both mechanical torque output and electric energy generation. This single motor-generator approach is coupled with a control strategy that ensures the needs of the most demanding or highest priority engine accessory or other component is met, while at the same time minimizing inefficient operation of other accessories or components by adapting their operation to the extent practical to the conditions that have been set to meet the greatest demand. In the control strategy discussed below, individual engine accessories are provided with clutches which, depending on the accessory, permits them to be selectively turned off, driven at a speed dictated by the accessory having the greatest demand or highest priority, or driven at a reduced speed using a variable-engagement clutch.

(111) When the engine accessories are being driven by the engine crankshaft, i.e., when the clutch 15 is engaged, each engine accessory is mechanically driven under a baseline or original control strategy (OCS) corresponding to how these accessories would be operated in a convention engine application without an FEMG system. In such a strategy the accessories having individual clutches are operated according to their individual baseline control schemes, with their clutches being fully engaged, partially engaged or disengaged in the same manner as in a non-hybrid internal combustion engine application.

(112) In contrast, when the clutch-pulley-damper unit clutch 15 is disengaged and the engine accessories begin to be powered by the motor-generator 3 using energy from the energy store 11, the FEMG control module variably controls the speed of the pulley 5, and hence the engine accessory drive belt in a manner that meets the current vehicle needs without providing more accessory drive torque than is required in the current operating conditions. Under such a variable speed control (VSC) strategy, the FEMG control module 13 uses stored data regarding the operating characteristics of the individual engine accessories to simultaneously control the various accessories in a manner that further minimizes the amount of electrical energy required to drive the motor-generator 3 in motor mode (the FEMG control module 13 may directly control the accessories, or issue signals to other modules such as the engine control module to command execution of the desired accessory operations). Moreover, despite the fact that the most efficient or desirable operating speed has been mapped for each accessory, because the motor-generator 3 drives all of the engine accessories on the same belt at one belt speed, when one accessory is operated at its optimum the others may be operating at suboptimal operating points. For this reason the FEMG control module 13 compares the preferred operating speeds of each of the accessories to their speeds when driven by the motor-generator 3 at a speed sufficient to meet the greatest accessory demand, and determines whether the accessories' individual clutches can be actuated to produce an individual accessory speed closer to the individual accessory's preferred operating speed. If possible, the FEMG control module will override the usual accessory clutch control strategy and activate the accessory clutches as needed to deliver individual accessory speeds that provide improved efficiency.

(113) Selection of appropriate engine accessory speeds begins with determination of a desired ideal operating speed of each accessory for the current operating conditions, using a control logic such as that shown in FIG. 26.

(114) Upon starting the accessory speed determination algorithm, in step S201 the FEMG control module 13 retrieves from its memory 201 data regarding the current vehicle operating conditions obtained from the vehicle's sensors and other controllers, the majority of which is provided to the FEMG control module 13 via CAN bus in accordance with the SAE J1939 network protocol, and determines the current operating conditions. This operation is a predicate to determining in step S202 whether the current operating conditions require operation of a particular accessory, such as the engine cooling fan. If the accessory is to be turned on, the routine proceeds to step S203 to determine whether the accessory is coupled to the accessory drive via an individual accessory multi-speed clutch.

(115) If at step S203 the FEMG control module 13 determines such an accessory clutch is present, the routine proceeds to step S204 for a determination of what would be the desired accessory operating speed for the determined operating condition. In the course of performing step S204, the FEMG control module 13 accesses information 202, for example in the form of look-up tables, characteristic curves or mathematical functions, from which it can ascertain an accessory operating speed at which the accessory operates efficiently in the current operating conditions. At step S205, the FEMG control module 13 compares the determined desired accessory operating speed to the speed of the accessory when its clutch is fully engaged, and modulates the accessory clutch to set an appropriate corresponding clutch operating state (e.g., a degree of clutch slip in a variable slip clutch or a particular reduction ratio in a clutch with discrete multiple speeds such as a 3-speed clutch). After modulating the accessory clutch as appropriate for the conditions, the FEMG control module 13 in step S207 checks to see whether the FEMG system motor mode has ended (i.e., determining whether the motor-generator 3 is to continue driving the accessory drive via pulley 5). If the system is still operating in the motor mode, control returns to the beginning of the accessory speed determination process to continue to assess accessory speed needs in view of the on-going operating conditions. If the motor mode is determined in step S207 to have ended, the FIG. 26 routine ends.

(116) If at step S203 the FEMG control module 13 determines a multi-speed accessory clutch is not present (i.e., the accessory speed cannot be modulated relative to the engine speed), the routine proceeds directly to step S206 to command the accessory's clutch to fully couple the accessory to the accessory drive. Control then shifts to step S207, where the motor mode evaluation described above is performed.

(117) The FIG. 26 algorithm is a component of the overall engine accessory control strategy of the present embodiment shown in FIG. 27. At the start of the FEMG system algorithm the FEMG control module 13 in step S301 retrieves from its memory 201 data received from the battery management system 12 to determine the state of charge of the energy store 11. Next, in step S302 the FEMG control module 13 retrieves from memory 201 data regarding the current vehicle operating conditions obtained from the vehicle's sensors and other controllers to determine the current operating condition in which the engine is operating (in this embodiment the evaluation in step S302 provides the information required in step S201 of the FIG. 26 accessory speed determination algorithm, and thus need not be repeated in step S322, below).

(118) After determining the current operating conditions, the FEMG control module 13 determines the mode in which the FEMG system should operate and commands engagement or disengagement of the clutch 15 of the clutch-pulley-damper unit 19 accordingly (step S303). If the clutch 15 is to be in an engaged state in which the pulley 5 is coupled to the damper 6 (and hence to the engine crankshaft), the determination of how the accessories are to be operated with the engine driving pulley 5 may be performed by the FEMG control module 13, or another accessory control module. In FIG. 27, the FEMG control module 13 at step S311 passes control of the engine accessory clutches to the vehicle's engine control module (ECM), which can determine engine accessory speeds in a manner comparable to the original control strategy (OCS). After hand-off of accessory control in step S311, processing ends at step S312.

(119) If at step S303 it is determined that motor-generator 3 is to electrically drive the accessories (i.e., the motor mode in which the clutch 15 of the clutch-pulley-damper unit 19 is in a disengaged state in which the pulley 5 is decoupled from the damper 6 and hence the crankshaft), in this embodiment the motor-generator 3 is controlled using the variable speed control (VSC) strategy.

(120) The VSC strategy is implemented here by first determining for each accessory a preferred accessory operating speed in step S322, taking into account information on all of the accessories' characteristics and variables evaluated in step S321.

(121) At step S323 the FEMG control module 13 determines whether at least one accessory that could be driven by the motor-generator 3 is in on, i.e., in a state in which it is to be driven via pulley 5 by motor-generator 3. If there is no accessory operation demand under the current conditions, control is returned to step S303.

(122) If it is determined in step S323 that there is at least one accessory in an on state, the FEMG control algorithm in step S324 determines whether more than one accessory needs to be driven by the motor-generator 3 (i.e., more than one accessory on). If there is only a single accessory with a torque demand the control process proceeds with a subroutine that is focused solely on the operation of that one on accessory. Thus, at step S325 the motor-generator speed needed to drive the single accessory at its preferred operating speed is calculated, the accessory's individual drive clutch is commanded to fully engage in step S326, and the motor-generator 3 in step S327 is commanded to operate at the speed determined in step S325. Because the motor-generator's speed is variably-controlled in this embodiment, the pulley speed 5 may be set at precisely the level required to drive the highest-demand engine accessory. Control is then returned to the start of the control algorithm.

(123) If at step S324 it is determined that more than one accessory needs to be driven by the motor-generator 3, in accordance with the VSC strategy at step S328 the FEMG control module 13 determines for each accessory what motor-generator speed would be needed to drive the accessory at its individual preferred accessory operating speed. The calculated speeds are then compared in step S329 to identify the highest motor-generator speed demand from the on accessories. The FEMG control module 13 then commands the individual clutch of the accessory needing the highest motor-generator speed to fully engage in step S330, in step S331 commands the motor-generator 3 to operate that the needed highest motor-generator speed. As a part of the VSC strategy, in step S332 the FEMG control module controls the operation of individual accessory clutches of the remaining on accessories equipped with individual clutches to adapt these accessories' operation to the needed highest motor-generator speed set in step S329. For example, because the set motor-generator speed (the speed needed to serve the accessory needing the highest motor-generator speed) is higher than the speed needed by a remaining accessories to operate at their preferred speeds, if an accessory is equipped with an individual clutch that can be partially engaged (e.g., slipped), that clutch may be commanded to allow enough slip to let its accessory's speed be closer to its preferred operating speed (as determined in step S322). Control is then returned to the start of the control algorithm.

(124) The following provides an example of the execution of the foregoing method for the case of a vehicle with three accessories driven from the crankshaft pulley, an engine cooling fan, an air conditioning compressor and an air compressor.

(125) In this example the engine cooling fan is equipped with a fan clutch with multiple speed capability, such as a three speed or variable speed clutch (e.g., a viscous fan clutch). The air conditioner and air compressors have individual on/off clutches with only engaged and disengaged states. The FEMG control module 13 controls the operating state of each of the accessory clutches. The final speed of each accessory is a function of the belt pulley drive ratio, the motor-generator speed and the nature of the accessory's clutch (i.e., on/off, variable slip or multiple reduction ratio steps).

(126) In this simplified example, for a given set of vehicle operating conditions, the preferred operating point of each accessory and the corresponding motor-generator speed to obtain the preferred operating point are: engine cooling fan operating at 1050 rpm (a fan speed which requires a motor-generator speed of 1050 rpm/1.1 ratio between fan pulley and pulley 5, times 2:1 gearbox reduction ratio=1909 rpm); air conditioning compressor operating at 1100 rpm (corresponding to a motor-generator speed of 1294 rpm); and air compressor operating at 2000 rpm (corresponding to a motor-generator speed of 2667 rpm).

(127) If the FEMG control module 13 determines operation of the air compressor is the highest priority in the given conditions (for example, when stored compressed air amount is approaching minimum safety levels for pneumatic brake operation), the FEMG control module 13 will command the motor-generator 3 to run at the 2667 rpm required to support the air compressor's 2000 rpm speed requirement. However, this motor-generator speed is substantially higher than the speeds required by the engine cooling fan or the air conditioning compressor (at the 2667 rpm motor-generator speed, the engine cooling fan speed and air conditioning compressor speed would be 1467 rpm and 2267 rpm, respectively). The FEMG control module 13, having access to the engine accessory operating curves and depending on the nature of the other accessories' clutches, could then adjust the clutches' engagements to operate the other accessories closer to their preferred operating speeds. For example, if the fan was equipped with a variable slip clutch, the FEMG control module could command an amount of fan clutch slip to provide the preferred engine cooling fan speed of 1100 rpm. Similarly, while the air conditioning compressor may only have an on/off clutch and thus would be driven at 1467 rpm when its clutch is engaged (rather than the preferred speed of 1050 rpm), the FEMG control module could control operation of the on/off clutch of the air conditioning compressor to reduce the duty cycle of the air conditioning compressor to a point that the current air conditioning demand could be met by only periodically operating the air conditioner at 1467 rpm. This approach provides the FEMG control module the ability to meet the needs of the currently-most demanding engine accessory while reducing waste of energy by driving other accessories at higher speeds than necessary or at an unnecessarily high duty cycle (e.g., 100%).

(128) In a further example, the engine may be equipped with accessories that cannot be disconnected from a drive belt driven by the pulley 5. In such a case, the FEMG control module 13 may determine upon consideration of the operating curves that the greatest overall system energy efficiency may be obtained by compromise. For example, assume the air compressor is currently presenting the greatest demand and it would be preferable to operate the air compressor at the 2000 rpm speed at which the compressor is most efficient. If the FEMG control module then determines that an engine coolant pump being driven at the 2667 rpm motor generator speed would be operating at an undesirably low efficiency (i.e., operating at a pump speed that significantly increases the pump's energy consumption) and the vehicle conditions allow the air compressor to be operated at a lower speed (for example, where the current need is topping off the compressed air storage tanks, rather than meeting an urgent, safety-related compressed air demand), the FEMG control module can command a lower motor-generator speed at which the engine coolant pump operates at a higher level of efficiency (e.g., 2400 rpm), even though the air compressor operates at a slight decreased efficiency at this speed, with the result that the overall combined engine coolant pump and air compressor operation increases overall system efficiency as compared to operating these accessories at a motor-generator speed of 2667 rpm.

(129) The foregoing disclosure has been set forth merely to illustrate the invention and is not intended to be limiting. Because such modifications of the disclosed embodiments incorporating the spirit and substance of the invention may occur to persons skilled in the art, the invention should be construed to include everything within the scope of the appended claims and equivalents thereof.

LISTING OF REFERENCE LABELS

(130) 1 air compressor

(131) 2 air conditioning compressor

(132) 3 motor-generator

(133) 4 drive unit gears

(134) 5 pulley

(135) 6 damper

(136) 7 engine cooling fan

(137) 8 engine

(138) 9 vehicle batteries

(139) 10 DC/DC converter

(140) 11 energy store

(141) 12 battery management system

(142) 13 FEMG electronic control unit

(143) 14 AC/DC power inverter

(144) 15 clutch

(145) 16 gearbox

(146) 17 flange shaft

(147) 18 rotor shaft

(148) 19 clutch-pulley-damper unit

(149) 20 engine coolant radiator

(150) 21 belt drive portions

(151) 22 clutch actuator

(152) 23 clutch plates

(153) 24 clutch spring

(154) 25, 26 dog clutch elements

(155) 27 clutch throw-out rod

(156) 28 bolt holes

(157) 29 external splines

(158) 30 internal splines

(159) 31, 32 dogs

(160) 33 spring

(161) 34 bearings

(162) 35 gearbox housing clamshell

(163) 36 pulley-end reduction gear

(164) 37 middle reduction gear

(165) 38 motor-generator-end reduction gear

(166) 39 bearings

(167) 40 holes

(168) 41 diaphragm

(169) 42 cover

(170) 43 shaft hole

(171) 44 mounting flange

(172) 45 mounting ring

(173) 46 nut

(174) 47 crankshaft

(175) 48 oil pan

(176) 49 chassis rail

(177) 50 engine mount

(178) 51 mounting bracket

(179) 52 holes

(180) 53 holes

(181) 54 bracket arms

(182) 55 motor-generator gearbox side

(183) 56 mounting studs

(184) 57 rotor shaft bore

(185) 58 low-voltage connection

(186) 59 high-voltage connection

(187) 60 coolant passage

(188) 61 electronics cooling passage portion

(189) 62 engine control unit

(190) 64 sensors

(191) 65 SAE J1939 bus

(192) 66 vehicle equipment

(193) 67 DC bus

(194) 68A-68F control lines

(195) 79 transistor control line

(196) 70 DC/DC voltage converter

(197) 71 DC/DC converter

(198) 72 12 V battery

(199) 73 12 V loads

(200) 74 DC/DC converter transistor drive circuit

(201) 75 DC/DC converter output

(202) 76 transformer primary winding

(203) 77 transformer

(204) 78 AC phase connection

(205) 79 circuit board

(206) 80 IGBT pack

(207) 81 IGBT driver circuits

(208) 82 EMI filter and DC capacitors

(209) 83 FEMG control module micro controller

(210) 101 motor-generator clutch position sensor

(211) 102 motor-generator speed sensor

(212) 103 engine accessory clutch positions

(213) 104 air compressor state sensors

(214) 105 dynamic heat generator state sensors

(215) 106 FEMG coolant temperature sensor

(216) 107 FEMG coolant pressure sensor

(217) 108 12V battery voltage sensor

(218) 111 brake controller

(219) 112 retarder controller

(220) 113 EAC controller

(221) 114 transmission controller

(222) 115 dashboard controller

(223) 120 individual engine accessory clutches

(224) 121 FEMG coolant pump

(225) 201 FEMG control module memory

(226) 202 FEMG control module operating parameter storage

(227) 303 clutch throw-out rod bushing

(228) 304 busing bearing

(229) 305 compressed air fitting

(230) 306 fastener

(231) 307 torque arm

(232) 308 anchor point

(233) 309 AC-DC converter

(234) 310 off-vehicle power