AN OIL DISTRIBUTOR FOR A LUBRICATING AND COOLING SYSTEM IN A POWERTRAIN

Abstract

An oil distributor is provided for a lubricating and cooling system in a powertrain, comprising a housing with a first oil outlet connected to a first oil chamber and a first oil circuit and a second oil outlet connected to a second oil chamber and a second oil circuit; and a piston arranged in a cavity of the housing and movable between first and second positions and comprising: a first bore partly constituting the second oil chamber; and a second bore connecting the first bore with an outer periphery of the piston, so that when the piston is in the first position, the first oil inlet is connected to the first oil chamber and the first oil outlet, and when the piston is in the second position, the first oil inlet is connected to the second oil chamber and the second oil outlet.

Claims

1. An oil distributor for a lubricating and cooling system in a powertrain, the oil distributor comprising: a housing provided with at least one first oil inlet and at least two oil outlets, wherein a first oil outlet is connected to a first oil chamber and wherein a second oil outlet of said at least two oil outlets is connected to a second oil chamber; and a piston arranged in a cavity of the housing, which piston is movable between a first and a second position, wherein the first oil outlet of said housing is adapted to be connected to a first oil circuit and the second oil outlet of said at least two oil outlets is adapted to be connected to a second oil circuit, wherein the piston comprises a first bore directed in a longitudinal direction of the piston, wherein the second oil chamber is at least in part constituted by the first bore in the piston, and wherein the piston comprises a second bore connecting the first bore with an outer periphery of the piston, so that when the piston is in the first position, the at least one first oil inlet of said housing is connected to the first oil chamber and the first oil outlet of said at least two oil outlets, and when the piston is in the second position, the at least one first oil inlet of said housing is connected to the second oil chamber and the second oil outlet of said at least two oil outlets.

2. The oil distributor according to claim 1, wherein the at least one first oil inlet and the at least two oil outlets are so arranged in the housing of the oil distributor that the at least one first oil inlet is connected to both the first and second oil chambers and thus to the first and second oil outlets, outlet when the piston is arranged in a position between the first and the second position.

3. The oil distributor according to claim 1, wherein a second oil inlet is arranged in the housing of the oil distributor and a third bore is arranged in the piston, which connects the first bore with an outer periphery of the piston, so that when the piston is in the first position, the second oil inlet is connected to the second oil chamber and the second oil outlet.

4. The oil distributor according to claim 3, wherein a bypass channel is arranged between the first oil chamber and another position in the cavity of the housing, so that when the piston is in the second position, the second oil inlet is connected to the first oil chamber and the first oil outlet via the bypass channel.

5. The oil distributor according to claim 4, wherein a cut out is arranged in the piston, so that when the piston is in the second position, the second oil inlet is connected to the bypass channel by means of the cut out in the piston.

6. The oil distributor according to claim 3, wherein the second oil inlet and the at least two oil outlets are so arranged in the housing of the oil distributor that the second oil inlet is connected to both the first and second oil chambers and thus to the first and second oil outlets when the piston is arranged in a position between the first and the second position.

7. A lubricating and cooling system in a powertrain, comprising: a first oil circuit for cooling a first powertrain component; a second oil circuit for cooling a second powertrain component; and an oil distributor comprising: a housing provided with at least one first oil inlet and at least two oil outlets, wherein a first oil outlet is connected to a first oil chamber and wherein a second oil outlet of said at least two oil outlets is connected to a second oil chamber; and a piston arranged in a cavity of the housing, which piston is movable between a first and a second position, wherein the first oil outlet of said housing is adapted to be connected to a first oil circuit and the second oil outlet of said at least two oil outlets is adapted to be connected to a second oil circuit, wherein the piston comprises a first bore directed in a longitudinal direction of the piston, wherein the second oil chamber is at least, in part, constituted by the first bore in the piston, and wherein the piston comprises a second bore connecting the first bore with an outer periphery of the piston, so that when the piston is in the first position, the at least one first oil inlet of said housing is connected to the first oil chamber and the first oil outlet of said at least two oil outlets, and when the piston is in the second position, the at least one first oil inlet of said housing is connected to the second oil chamber and the second oil outlet of said at least two oil outlets.

8. The lubricating and cooling system according to claim 7, wherein the first powertrain component is an electrical machine and the second powertrain component is gears and bearings in a gearbox.

9. The lubricating and cooling system according to claim 7, wherein an electrical controlled oil pump is connected to the at least one first oil inlet.

10. The lubricating and cooling system according to claim 7, wherein a mechanical controlled oil pump is connected to the second oil inlet.

11. A powertrain having a lubricating and cooling system, in turn, comprising an oil distributor comprising: a housing provided with at least one first oil inlet and at least two oil outlets, wherein a first oil outlet is connected to a first oil chamber and wherein a second oil outlet of said at least two oil outlets is connected to a second oil chamber; and a piston arranged in a cavity of the housing, which piston is movable between a first and a second position, wherein the first oil outlet of said housing is adapted to be connected to a first oil circuit and the second oil outlet of said at least two oil outlets is adapted to be connected to a second oil circuit, wherein the piston comprises a first bore directed in a longitudinal direction of the piston, wherein the second oil chamber is at least, in part, constituted by the first bore in the piston, and wherein the piston comprises a second bore connecting the first bore with an outer periphery of the piston, so that when the piston is in the first position, the at least one first oil inlet of said housing is connected to the first oil chamber and the first oil outlet of said at least two oil outlets, and when the piston is in the second position, the at least one first oil inlet of said housing is connected to the second oil chamber and the second oil outlet of said at least two oil outlets.

12. A vehicle having a lubricating and cooling system, in turn, comprising an oil distributor comprising: a housing provided with at least one first oil inlet and at least two oil outlets, wherein a first oil outlet is connected to a first oil chamber and wherein a second oil outlet of said at least two oil outlets is connected to a second oil chamber; and a piston arranged in a cavity of the housing, which piston is movable between a first and a second position, wherein the first oil outlet of said housing is adapted to be connected to a first oil circuit and the second oil outlet of said at least two oil outlets is adapted to be connected to a second oil circuit, wherein the piston comprises a first bore directed in a longitudinal direction of the piston, wherein the second oil chamber is at least, in part, constituted by the first bore in the piston, and wherein the piston comprises a second bore connecting the first bore with an outer periphery of the piston, so that when the piston is in the first position, the at least one first oil inlet of said housing is connected to the first oil chamber and the first oil outlet of said at least two oil outlets, and when the piston is in the second position, the at least one first oil inlet of said housing is connected to the second oil chamber and the second oil outlet of said at least two oil outlets.

13. A method of controlling a lubricating and cooling system in a powertrain, the system comprising an oil distributor comprising a housing provided with at least one first oil inlet and at least two oil outlets, wherein a first oil outlet is connected to a first oil chamber and wherein a second oil outlet of said at least two oil outlets is connected to a second oil chamber; and a piston arranged in a cavity of the housing, which piston is movable between a first and a second position, the piston comprising a first bore directed in a longitudinal direction of the piston, so that the second oil chamber is at least in part constituted by the first bore in the piston, wherein the piston comprises a second bore connecting the first bore with an outer periphery of the piston, so that when the piston is in the first position the at least one first oil inlet is connected to the first oil chamber and the first oil outlet and when the piston is in the second position the at least one first oil inlet is connected to the second oil chamber and the second oil outlet wherein a first oil circuit for cooling a first powertrain component is connected to the first oil outlet of said housing and a second oil circuit for lubricating a second powertrain component is connected to the second oil outlet of said at least two oil outlets, the method comprises: a) controlling a pressure and flow of oil to the at least one first oil inlet by means of an electrical controlled oil pump connected to the at least one first oil inlet; and b) controlling a position of the piston in order to control the pressure and flow of oil through the first oil outlet and into the first oil circuit for cooling the first powertrain component and in order to control the pressure and flow of oil through the second oil outlet and into the second oil circuit for lubricating the second powertrain component.

14. The method according to claim 13, further comprising: c) controlling the pressure and flow of oil to a second oil inlet by means of a mechanical controlled oil pump connected to the second oil inlet; and d) controlling the position of the piston in order to control the pressure and flow of oil through the first oil outlet and into the first oil circuit for cooling the first powertrain component and/or in order to control the pressure and flow of oil through the second oil outlet and into the second oil circuit for lubricating the second powertrain component.

15. The method according to claim 13, further comprising: e) cooling the oil in the first oil circuit by means of an oil cooler.

16. (canceled)

17. (canceled)

18. A computer program product comprising computer program code stored on a non-transitory computer-readable medium, said computer program product used for controlling a lubricating and cooling system in a powertrain, the system comprising an oil distributor comprising a housing provided with at least one first oil inlet and at least two oil outlets, wherein a first oil outlet is connected to a first oil chamber and wherein a second oil outlet of said at least two oil outlets is connected to a second oil chamber; and a piston arranged in a cavity of the housing, which piston is movable between a first and a second position, the piston comprising a first bore directed in a longitudinal direction of the piston, so that the second oil chamber is at least in part constituted by the first bore in the piston, wherein the piston comprises a second bore connecting the first bore with an outer periphery of the piston, so that when the piston is in the first position the at least one first oil inlet is connected to the first oil chamber and the first oil outlet, and when the piston is in the second position the at least one first oil inlet is connected to the second oil chamber and the second oil outlet; wherein a first oil circuit for cooling a first powertrain component is connected to the first oil outlet of said housing and a second oil circuit for lubricating a second powertrain component is connected to the second oil outlet of said at least two oil outlets, said computer program code comprising computer instructions to cause one or more control units to perform the following operations: a) controlling a pressure and flow of oil to the at least one first oil inlet by means of an electrical controlled oil pump connected to the at least one first oil inlet; and b) controlling a position of the piston in order to control the pressure and flow of oil through the first oil outlet and into the first oil circuit for cooling the first powertrain component and in order to control the pressure and flow of oil through the second oil outlet and into the second oil circuit for lubricating the second powertrain component.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Below is a description of, as examples, preferred embodiments with reference to the enclosed drawings, in which:

[0043] FIG. 1 shows schematically a vehicle in a side view with an oil distributor for a lubricating and cooling system according to an embodiment,

[0044] FIG. 2a shows a cross section of the oil distributor according to an embodiment,

[0045] FIG. 2b shows a back side view of the oil distributor according to an embodiment,

[0046] FIG. 3 shows a cross section of the oil distributor according to an embodiment,

[0047] FIG. 4 shows a cross section of the oil distributor according to an embodiment,

[0048] FIG. 5 shows schematically a lubricating and cooling system according to an embodiment, and

[0049] FIG. 6 shows a flow chart for a method of controlling a lubricating and cooling system in a powertrain according to an embodiment.

DETAILED DESCRIPTION OF THE INVENTION

[0050] FIG. 1 shows schematically a vehicle 1 in a side view, which may be provided with an oil distributor 2 according to an embodiment. The vehicle 1 may also be provided with an internal combustion engine 4, a clutch 5, a gearbox 6, a propeller shaft 10 and drive wheels 8. The combustion engine 4 may be coupled to the gearbox 6 via the clutch 5. The gearbox 6 may be connected to the drive wheels 8 of the vehicle 1 via the propeller shaft 10. Instead of or in combination with the internal combustion engine 4 the vehicle 1 may be provided with an electrical machine 12 as part of a powertrain 14 in the vehicle 1. The gearbox 6 may comprise gears 16 and bearings 18.

[0051] FIG. 2a shows a cross section of the oil distributor 2 according to an embodiment. The oil distributor 2 may comprise a housing 20 provided with a first oil inlet 22 and a second oil inlet 24 (shown in FIG. 2b). Also a first oil outlet 26 and a second oil outlet 28 may be arranged in the housing 20. However, at least one first oil inlet 22 and at least two oil outlets 26, 28 may be arranged in the housing 20. The first oil outlet 26 may be connected to a first oil chamber 30 and the second oil outlet 28 may be connected to a second oil chamber 32. A piston 34 may be arranged in a cavity 36 of the housing 20, which piston 34 may be movable between a first and a second position. A position sensor 37 may be arranged at the housing 20 for receiving information about the position of the piston 34 in the oil distributor 2. In FIG. 2a the piston 34 has been moved to the first position. The piston 34 may comprise a first bore 38 directed in a longitudinal direction of the piston 34. The second oil chamber 32 may be at least in part constituted by the first bore 38 in the piston 34. The piston 34 may comprise a second bore 40 connecting the first bore 38 with an outer periphery of the piston 34. When the piston 34 is in the first position the first oil inlet 22 may be connected to the first oil chamber 30 and the first oil outlet 26. A third bore 42 may be arranged in the piston 34, which connects the first bore 38 with an outer periphery of the piston 34. When the piston 34 is in the first position the second oil inlet 24 may be connected to the second oil chamber 32 and the second oil outlet 28. An actuating means 44 (see FIG. 5) may be arranged for moving the piston 34 to the different positions in the oil distributor 2. An air inlet 46 for pneumatically control the position of the piston 34 may be arranged in the housing 20. A spring 48 may be arranged in the first oil chamber 30 and in the first bore 38 of the piston 34. When over pressurized air is provided through the air inlet 46, the force from the spring 48 may be exceeded and the piston 34 will move in the direction of the second position. When the air pressure is relieved the force from the spring 48 may move the piston 34 towards the first position. Sealing elements 50 are arranged on the piston 34 for sealing of different volumes along the length of the piston 34.

[0052] FIG. 2b shows a back side view of the oil distributor 2 according to an embodiment. The second oil inlet 24 may be arranged in the housing 20 of the oil distributor 2. The back side of the housing 20 of the oil distributor 2 may be configured to be connected to the gearbox 6. The second oil inlet 24 may therefore be connected to an opening (not disclosed) in the gearbox 6 from which oil is delivered to the oil distributor 2. The housing 20 of the oil distributor 2 may also be provided with holes 52 for fasteners (not disclosed), so that the oil distributor 2 can be fixed to the gearbox 6. A bypass channel 54 may be arranged between the first oil chamber 30 and a bypass opening 58 at another position in the cavity 36 of the housing 20. The bypass channel 54 may make it possible to connect the second oil inlet 24 to the first oil chamber 30 and the first oil outlet 26. The second oil inlet 24 may increase the oil flow and increase the possibility to accurately control the oil distributor 2 and independently optimize the cooling and lubrication with their required parameters for enabling high cool oil flow for heat generating components, and pressured circulated oil for lubrication of components.

[0053] FIG. 3 shows a cross section of the oil distributor 2 according to an embodiment. In FIG. 3 the piston 34 has been moved to the second position. When the piston 34 is in the second position the first oil inlet 22 may be connected to the second oil chamber 32 and the second oil outlet 28. When the piston 34 is in the second position the second oil inlet 24 may be connected to the first oil chamber 30 and the first oil outlet 26 via the bypass channel 54. A cut out 56 may be arranged in the piston 34. When the piston 34 is in the second position the second oil inlet 24 may be connected to the bypass channel 54 by means of the cut out 56 arranged in the piston 34. The cut out 56 in the piston 34 may have an extension in the longitudinal direction of the piston 34 which is adapted to the size of the bypass opening 58 at the another position in the cavity 36 of the housing 20, so that the second oil inlet 24 may be connected to the bypass channel 54 through the bypass opening 58 and by means of the cut out 56 in the piston 34.

[0054] FIG. 4 shows a cross section of the oil distributor 2 according to an embodiment. In FIG. 4 the piston 34 has been moved to a position between the first and the second positions, which may be an intermediate position. The first oil inlet 22 and the first and second oil outlets 26, 28 may be so arranged in the housing 20 of the oil distributor 2 that the first oil inlet 22 may be connected to both the first and second oil chambers 30, 32 and thus to the first and second oil outlet 26, 28 when the piston 34 is arranged in a position between the first and the second position. The second oil inlet 24 and the first and second oil outlets 26, 28 may be so arranged in the housing 20 of the oil distributor 2 that the second oil inlet 24 may be connected to both the first and second oil chambers 30, 32 and thus to the first and second oil outlet 26, 28 when the piston 34 is arranged in the position between the first and the second position. Thus, the movable piston 34 may connect the first oil inlet 22 with both chambers and both oil outlets simultaneously. Also, the movable piston 34 may connect the second oil inlet 24 with both oil chambers 30, 32 and both oil outlets 26, 28 simultaneously. The piston 34 may in the intermediate position leave a pre-defined flow for booth cooling and lubrication.

[0055] The movable piston 34 may in the intermediate position connect the at least one first oil inlet 22 with both chambers 30, 32 and both oil outlets 26, 28 simultaneously. The piston 34 may be an on demand piston 34 which direct links together the at least one first oil inlet 22 with one of the chambers 30, 32. The piston 34 may close one of the two chambers 30, 32 and as a result supplying an oil flow for cooling or supplying oil for lubrication. The movable piston 34 may be a one way air cylinder provided with a spring 48 for returning the piston 34 to the first and the intermediate position. Other actuating means 44 may be a two way air cylinder or an electrical power means with high precision that may set the piston 34 in an accurate position.

[0056] FIG. 5 shows schematically a lubricating and cooling system 60 according to an embodiment. The lubricating and cooling system 60 comprises a first oil circuit 62 for cooling a first powertrain component, such as the electrical machine 12. The system 60 also comprises a second oil circuit 64 for lubricating a second powertrain component, such as bearings 18 and gears 16 in a gearbox 6. The electrical machine 12 generates heat and may be cooled to a preferred working temperature in order to achieve an optimized function and durability. A radiator or oil cooler 66 is arranged in the first oil circuit 62 for cooling the oil. A thermostat 68 is arranged in a bypass conduit 70. When the oil temperature is over a certain temperature, the thermostat 68 opens and oil may bypass the oil cooler 66. The gearbox 6 may comprise bearings 18 and gears 16 which may be lubricated in order to achieve an optimized function and durability. The system 60 further comprises the oil distributor 2. The first oil outlet 26 of the oil distributor 2 may be adapted to be connected to the first oil circuit 62 and the second oil outlet 28 of the oil distributor 2 may be adapted to be connected to the second oil circuit 64. The oil distributor 2 thus supplies oil in two different circuits 62, 64. Each circuit 62, 64 can be optimized for its purpose such as to secure the cooling performance of an electrical machine 12 and to secure the endurance of transmission components, such as the bearings 18 and the gears 16 in the gearbox 6.

[0057] An electrical controlled oil pump 72 may be connected to the at least one first oil inlet 22. The electrical oil pump 72 may be used for supplying oil both to the first oil circuit 62 for cooling the first powertrain component such as the electrical machine 12 and to the second oil circuit 64 for cooling the second powertrain component such as bearings 18 and gears 16 in the gearbox 6. A mechanical controlled oil pump 74 may be connected to the second oil inlet 24. The mechanical oil pump 74 may be used for supplying oil both to the first oil circuit 62 for cooling the first powertrain component 12 and to the second oil circuit 64 for cooling the second powertrain component 16, 18. Oil is collected in a container 76 and circulated in the circuits 62, 64 by means of the pumps 72, 74. Oil is returned to the container 76 by means of a return channel 78.

[0058] The electrical oil pump 72 may mainly be used for cooling and the mechanical oil pump 74 may mainly be used for lubrication. With the oil distributor 2 in place the first and second circuits 62, 64 may independently be optimized with their required parameters, which enable high cool oil flow to the electrical machine 12 for high performance, and pressured circulated oil for a durable lubrication system for components to be lubricated.

[0059] For some gearbox variants shafts in the gearbox 6 have no defined rotation direction and in some driving modes the mechanical oil pump 74 may be outside its operation field. In these operation modes it may be necessary to have an oil distributor 2 to switch and guide oil from the electrical oil pump 72 to lubrication positions. It is also energy efficient when there is a high oil flow from the mechanical oil pump 74, due to high rotation speed on rotating components in the gearbox 6, to switch and cool the electrical machine 12 by oil flow supplied by the mechanical oil pump 74 and lubricate the components in the powertrain 14 by oil supplied by the electric oil pump 72 at lower energy consumption. Downstream the electrical oil pump 72 a first check valve 77 may be arranged in order to stop an oil flow in the direction towards the electrical oil pump 72. Downstream the mechanical oil pump 74 a second check valve 79 may be arranged in order to stop an oil flow in the direction towards the mechanical oil pump 72.

[0060] The oil distributor 2 may also be used on powertrains 14 without an internal combustion engine 4 and when no gearbox 6 may be needed and therefore no mechanical connected oil pump 74 may be available. In these applications the electrical oil pump 72 may supply both the first and second oil circuits 62, 64 with oil. To ensure correct oil distribution the oil distributor 2 with predefined oil flow split may be needed instead of being dependent on a pressure difference which may differ depending on operation mode and oil temperature.

[0061] Such lubricating and cooling system 60 in a powertrain 14 may independently optimize the cooling- and lubrication with their required parameters for enabling high cool oil flow in the first oil circuit 62 for cooling the first powertrain component 12, and pressured circulated oil in the second oil circuit 64 for lubricating the second powertrain component 16, 18.

[0062] A control unit 80 may be connected to the actuating means 44 for controlling the piston 34 position and thus controlling the distribution of oil to the first and second oil circuits 62, 64. The position sensor 37 may be connected to the control unit 80 for receiving information about the position of the piston 34 in the oil distributor 2. The control unit 80 may also be connected to the pumps 72, 74. The oil flow of the electrical pump 72 may be controlled by the control unit 80 and may be related to the temperature of the electrical machine 12 and the operation mode of the vehicle 1. The thermostat 68 may be electric or mechanic. The thermostat 68 may be connected to the control unit 80 and be controlled in relation to the oil temperature. The electrical machine 12 may be connected to the control unit 80 for sensing the temperature of the electrical machine 12. A temperature sensor 82 arranged at the oil container 76 may be connected to the control unit 80 for sensing the temperature of the oil.

[0063] The control unit 80 may comprise a computer 84, or a link to a computer 84, comprising a computer program P with programme code for receiving the data containing the current temperature of the oil and the electrical machine 12 in order to calculate the suitable position of the piston 34. The program code may be executed in the computer 84. The control unit 80 may further comprise stored data in a memory M, or a link to readable data, containing oil flow and oil pressure parameters for the first and second oil circuits 62, 64 and for different vehicle operation modes to control the position of the piston 34 and to control the oil flow and oil pressure from the pumps 72, 74. A computer program product may comprise a computer-readable medium and the computer program, which computer program may be contained in said computer-readable medium.

[0064] FIG. 6 shows a flow chart for a method of controlling a lubricating and cooling system 60 in a powertrain according to an embodiment. The lubricating and cooling system 60 in the powertrain 14 may comprise the features described in the embodiments above.

[0065] The method may comprise the steps of:

[0066] a) controlling the pressure and flow of oil to the at least one first oil inlet 22 by means of an electrical controlled oil pump 72 connected to the at least one first oil inlet 22; and

[0067] b) controlling the position of the piston 34 in order to control the pressure and flow of oil through the first oil outlet 26 and into the first oil circuit 62 for cooling the first powertrain 14 component and in order to control the pressure and flow of oil through the second oil outlet 28 and into the second oil circuit 64 for lubricating the second powertrain component 16, 18.

[0068] Controlling of the pressure and flow of oil may be achieved by controlling the power to the electrical controlled oil pump 72. By also controlling the position of the piston 34 in order to control the pressure and flow of oil, a high cool oil flow for heat generating components, and pressured circulated oil for lubrication of components may be optimized independently.

[0069] The method may comprise the further steps of:

[0070] c) controlling the pressure and flow of oil to a second oil inlet 24 by means of a mechanical controlled oil pump 74 connected to the second oil inlet 24; and

[0071] d) controlling the position of the piston 34 in order to control the pressure and flow of oil through the first oil outlet 26 and into the first oil circuit 62 for cooling the first powertrain component 12 and/or in order to control the pressure and flow of oil through the second oil outlet 28 and into the second oil circuit 64 for lubricating the second powertrain component 16, 18.

[0072] Controlling of the pressure and flow of oil may be achieved by controlling the driving conditions of the transmission connected to the mechanical controlled oil pump 74. By also controlling the position of the piston 34 in order to control the pressure and flow of oil, a high cool oil flow for heat generating components, and pressurized circulated oil for transmission components may be optimized independently.

[0073] The method may comprise the further step of:

[0074] e) cooling the oil in the first oil circuit 62 by means of an oil cooler 66.

[0075] The first powertrain component may be an electrical machine 12. An electrical machine 12 generates heat and must be cooled to a preferred working temperature in order to achieve an optimized function and durability. When cooling the electrical machine 12 the heat generated by the electrical machine 12 may be transferred to the oil. For this reason the oil in the first oil circuit 62 may be cooled by means of an oil cooler 66.

[0076] The computer program comprising program code that, when said program code is executed in the computer 84, causes said computer 84 to carry out the above-mentioned method. The computer program product comprising the computer-readable medium and the computer program, which computer program is contained in said computer-readable medium.

[0077] The fluid for cooling and lubrication is described as oil. However, any oil or fluid that has cooling and lubrication properties may be used.

[0078] The foregoing description of the preferred embodiments has been furnished for illustrative and descriptive purposes. It is not intended to be exhaustive, or to limit the embodiments to the variants described. Many modifications and variations will obviously be apparent to one skilled in the art. The embodiments have been chosen and described in order to best explicate principles and practical applications, and to thereby enable one skilled in the art to understand the embodiments in terms of its various embodiments and with the various modifications that are applicable to its intended use. The components and features specified above may, within the framework of the embodiments, be combined between different embodiments specified.