Clutch Assembly, Motor Vehicle Powertrain, and Method for Operating a Powertrain

Abstract

A clutch assembly for a motor vehicle drive train includes a first clutch having a first output element, where the first clutch is a friction-locking clutch. The clutch assembly further includes a second clutch having a second output element, where the second clutch is a form-locking clutch, and where the first clutch and the second clutch have a shared input element. Additionally, the clutch assembly includes a single sliding element associated with the first clutch and the second clutch, the sliding element being movable by a single actuating unit between a first engagement position and a second engagement position axially offset from the first engagement position. The first clutch is engaged when the sliding element is in the first engagement position and the second clutch is engaged when the sliding element is in the second engagement position.

Claims

1-14. (canceled)

15. A clutch assembly (14) for a motor vehicle powertrain (10), comprising: a first clutch (K1) having a first output element (AG1), the first clutch (K1) being a friction-locking clutch; a second clutch (K2) having a second output element (AG2), the second clutch (K2) being a form-locking clutch (K2), the first clutch (K1) and the second clutch (K2) having a shared input element (EG); and a single sliding element (88) associated with the first clutch (K1) and the second clutch (K2), the sliding element (88) being movable by a single actuating unit (S1) between a first engagement position (X1) and a second engagement position (X2) axially offset from the first engagement position (X1), wherein the first clutch (K1) is engaged when the sliding element (88) is in the first engagement position (X1) and the second clutch (K2) is engaged when the sliding element (88) is in the second engagement position (X2).

16. The clutch assembly of claim 15, wherein the sliding element (88) has a neutral position (N) axially between the first and second engagement positions (X1, X2), the first clutch (K1) and the second clutch (K2) being disengaged when the sliding element (88) is in the neutral position.

17. The clutch assembly of claim 15, wherein the first clutch (K1) includes a piston (86), a friction interface arrangement (84) of the first clutch (K1) being compressible by the piston (86) to establish a frictional connection.

18. The clutch assembly of claim 17, wherein the piston (86) is rotationally fixed to the sliding element (88).

19. The clutch assembly of claim 15, wherein the sliding element (88) includes an axial bearing (100), the axial bearing (100) allowing the actuating unit (S1) to move the sliding element (88) toward the first engagement position (X1) to engage the first clutch (K1).

20. The clutch assembly of claim 19, wherein the sliding element (88) has a second shoulder (102), the axial bearing (100) being arranged at the second shoulder (102).

21. The clutch assembly of claim 15, wherein the sliding element (88) has a first shoulder (98) against which the actuating unit (S1) pushes to move the sliding element (88) into the second engagement position (X2) to engage the second clutch (K2).

22. A powertrain (10) for a motor vehicle comprising the clutch assembly (14) of claim 15, the powertrain (10) further comprising: a transmission arrangement (16) including a first sub-transmission (32) and a second sub-transmission (34), wherein a first input shaft (24) of the first sub-transmission (32) is connected to the first output element (AG1), and wherein a second input shaft (26) of the second sub-transmission (34) is connected to the second output element (AG2).

23. The powertrain of claim 22, further comprising one or both of: a first electric machine (56) connected to the first input shaft (24), and a second electric machine (60) connected to the second input shaft (26).

24. The powertrain of claim 23, further comprising: a third clutch (K3) for selectively connecting the first sub-transmission (32) and the second sub-transmission (34); and a gearshift clutch (E; C) for engaging a gear set (42; 38″) of the first sub-transmission (32), wherein the third clutch (K3) and the gearshift clutch (E; C) form a gearshift clutch assembly (66; 66″).

25. The powertrain of claim 23, wherein the first electric machine (56) is connected to the first input shaft (24) via a gear-step gear set (38; 42″) of the first sub-transmission (32), and wherein the second electric machine (60) is connected to the second input shaft (26) via a gear-step gear set (50) of the second sub-transmission (34).

26. The powertrain of claim 22, wherein the first sub-transmission (32) has three gear sets (36, 38, 42), each of the three gear sets being associated with a respective odd forward gear step, and wherein the second sub-transmission (34) has two or three gear sets (48, 50), each of the two or three gear sets being associated with a respective even forward gear step.

27. A method for operating the powertrain of claim 22, the method, during an internal combustion engine-driven operation or a hybrid operation, comprising: engaging the first clutch (K1) to use a gear step of the first sub-transmission; and engaging the first clutch (K1) and a third clutch (K3) to use a gear step of the second sub-transmission.

28. The method of claim 27, wherein, during a serial operation, the method comprises: disengaging the first clutch (K1); engaging the second clutch (K2); operating a second electric machine (60) as a generator by driving the second electric machine (60) by internal combustion engine-generated power with the second clutch engaged (K2); and providing input power from a first electric machine (56) to the transmission arrangement (16) for establishing a driving operation with the first clutch (K1) disengaged and with the second clutch engaged (K2).

Description

BRIEF DESCRIPTION OF THE FIGURES

[0082] Exemplary embodiments of the invention are represented in the drawing and are explained in greater detail in the following description, wherein

[0083] FIG. 1 shows a diagrammatic gear set representation of an embodiment of a hybrid drive train;

[0084] FIG. 2 shows a diagrammatic power flow representation of a further embodiment of a hybrid drive train;

[0085] FIG. 3 shows a gearshift table for an internal combustion engine-driven operation and a hybrid operation of the hybrid drive train from FIG. 1;

[0086] FIG. 4 shows a gearshift table for an electric motor-driven operation by the first electric machine;

[0087] FIG. 5 shows a gearshift table for an electric motor-driven operation by the second electric machine;

[0088] FIG. 6 shows a schematic of an embodiment of a clutch assembly according to the invention; and

[0089] FIG. 7 shows a partial longitudinal sectional representation of a further embodiment of a clutch assembly according to the invention.

DETAILED DESCRIPTION

[0090] Reference will now be made to embodiments of the invention, one or more examples of which are shown in the drawings. Each embodiment is provided by way of explanation of the invention, and not as a limitation of the invention. For example, features illustrated or described as part of one embodiment can be combined with another embodiment to yield still another embodiment. It is intended that the present invention include these and other modifications and variations to the embodiments described herein.

[0091] In FIG. 1, a hybrid drive train 10 for a motor vehicle, in particular a passenger car, is represented in diagrammatic form.

[0092] The hybrid drive train 10 includes an internal combustion engine 12, which is connected to an input element of a dual clutch assembly 14. The dual clutch assembly 14 is connected on the output side to a hybrid transmission arrangement 16. An output of the hybrid transmission arrangement 16 is connected to a power distribution unit 18, which is, for example, a mechanical differential that distributes the input power to two driven wheels 20L, 20R of the motor vehicle.

[0093] Moreover, the hybrid drive train 10 includes a control device 22 for controlling all components thereof.

[0094] The dual clutch assembly 14 is arranged on a first axis A1, which is coaxial to a crankshaft of the internal combustion engine 12. The dual clutch assembly 14 includes two friction clutches, or one friction clutch and an unsynchronized dog clutch. In the present case, the dual clutch assembly 14 includes two clutches, including a first clutch K1 and a second clutch K2. The two clutches K1, K2 have a shared input element EG, which is rotationally fixed to the crankshaft of the internal combustion engine 12. The first clutch K1 has a first output element AG1. The second clutch K2 has a second output element AG2. The output elements AG1, AG2 are arranged coaxially to one another.

[0095] The transmission arrangement 16 includes a first input shaft 24 and a second input shaft 26. The input shafts 24, 26 are arranged coaxially to one another and to the first axis A1. The first input shaft 24 is an inner shaft. The second input shaft 26 is a hollow shaft.

[0096] Moreover, the transmission arrangement 16 includes a countershaft 28, which is an output shaft 28 and is arranged coaxially to a second axis A2. The output shaft 28 is connected via an output gear set 30 to the power distribution unit 18, which is arranged coaxially to a third axis A3.

[0097] A parking interlock gear P is rotationally fixable at the output shaft 28 or at an input element of the power distribution unit 18. The hybrid drive train 10 is immobilized by the parking interlock gear P. The associated parking lock device is not represented, for the sake of clarity.

[0098] The transmission arrangement 16 has a first sub-transmission 32 and a second sub-transmission 34. The sub-transmissions 32, 34 are arranged axially offset with respect to one another. The first sub-transmission 32 is arranged adjacent to a first axial end of the transmission arrangement 16. The second sub-transmission 34 is arranged adjacent to a second axial end of the transmission arrangement 16, wherein the second axial end is adjacent to the dual clutch assembly 14. The sub-transmissions 32, 34 each have a plurality of engageable gear sets, which, in the engaged condition, connect an input shaft and the output shaft 28.

[0099] The first sub-transmission 32 has a first gear set 36 for a first forward gear step 1 and a second gear set 38 for a third forward gear step 3. The second gear set 38 is arranged closer to the first axial end of the transmission arrangement 16 than the first gear set 36. A first gearshift clutch assembly 40 is arranged between the first gear set 36 and the second gear set 38 and coaxially to the second axis A2. The first gearshift clutch assembly 40 includes a first gearshift clutch A for engaging the first gear set 36 and a second gearshift clutch C for engaging the second gear set 38. The two gearshift clutches A, C are alternately engageable and are unsynchronized dog clutches. The engagement of a gear set includes the rotationally fixed connection of an idler gear of the particular gear set to an associated shaft. In the present case, for example, the first gear set 36 is engaged, in that an idler gear of the first gear set 36, which is rotatably mounted at the output shaft 28, is rotationally fixed to the output shaft 28, in order to bring the first gear set into the power flow in this way.

[0100] Moreover, the first sub-transmission 32 has a third gear set 42 for a fifth forward gear step 5. The third gear set 42 is arranged closer to the second axial end of the transmission arrangement 16 than the first gear set 36.

[0101] The third gear set 42 is engageable by a third gearshift clutch E and has an idler gear, which is rotatably mounted at the first input shaft 24.

[0102] The second sub-transmission 34 has a fourth gear set 48 for a second forward gear step 2 and a fifth gear set 50 for a fourth forward gear step 4. The fifth gear set 50 is arranged closer to the second axial end than the fourth gear set 48. A second gearshift clutch assembly 52 is arranged between the fourth and fifth gear sets 48, 50 and, in fact, coaxially to the second axis A2. The second gearshift clutch assembly 52 has a fourth gearshift clutch B for engaging the fourth gear set 48 and a fifth gearshift clutch D for engaging the fifth gear set. The fourth and fifth gearshift clutches B, D are accommodated in the second gearshift clutch assembly 52 such that they are alternately actuatable.

[0103] Consequently, the transmission arrangement 16 has five gear set planes, namely, starting from the second axial end toward the first axial end, in the following order: fifth gear set 50 for the fourth forward gear step 4, fourth gear set 48 for the second forward gear step 2, third gear set 42 for the fifth forward gear step 5, first gear set 36 for the first forward gear step 1, and second gear set 38 for the third forward gear step 3.

[0104] Moreover, the hybrid drive train 10 includes a first electric machine 56, which is arranged coaxially to a fourth axis A4. The first electric machine 56 has a first pinion 58, which is rotationally fixed to a rotor of the first electric machine 56 and is coaxial to the fourth axis A4. The first pinion, which is also referred to as the first machine pinion, is connected to a gear-step gear set of the first sub-transmission 32, in the present case to the second gear set 38 for the third forward gear step 3 via a first intermediate gear 59 rotatably mounted at an axle (not described in greater detail). More precisely, the first pinion 58 meshes with the first intermediate gear 59, and the first intermediate gear 59 meshes with a fixed gear of the second gear set 38, where the fixed gear is rotationally fixed to the first input shaft 24.

[0105] Moreover, the hybrid drive train 10 has a second electric machine 60, which is arranged axially parallel to the input shafts 24, 26 and, in fact, coaxially to a fifth axis A5. The second electric machine has a second pinion (second machine pinion) 62 arranged coaxially to the fifth axis A5. The second pinion 62 is connected to the second input shaft 26 via a gear-step gear set of the second sub-transmission 34. In the present case, the second pinion 62 is connected to the fifth gear set 50 for the fourth forward gear step 4 via a second intermediate gear 63. More precisely, the second pinion 62 meshes with the second intermediate gear 63 rotatably mounted at an axle (not described in greater detail), and the second intermediate gear 63 meshes with a fixed gear of the fifth gear set 50, where the fixed gear is rotationally fixed to the second input shaft 26.

[0106] The five axes A1, A2, A3, A4, A5 are all aligned in parallel with one another.

[0107] The dual clutch assembly 14 is arranged adjacent to the second axial end of the transmission arrangement 16, as mentioned above. The output gear set 30 is also arranged on the second axial side of the transmission arrangement 16 and is preferably axially aligned with the dual clutch assembly 14 or is situated approximately in a plane therewith. The parking interlock gear P is fixable at the output shaft 28 between the output gear set 30 and the fifth gear set 50.

[0108] In the hybrid drive train 10, the electric machines 56, 60 are each preferably connected to a gear-step gear set of its associated sub-transmission that is associated with the highest gear step of that sub-transmission. For this purpose, it is useful in the first sub-transmission 32 to interchange the second and third gear sets 38, 42 such that the first gearshift clutch assembly 40 includes the first gearshift clutch A and the third gearshift clutch E for the fifth forward gear step 5, and the second gearshift clutch C for engaging the third forward gear step 3 is arranged at the first input shaft 24. Moreover, the electric machines 56, 60 are each connected via a gear-step gear set to its particular sub-transmission that is preferably arranged adjacent to an axial end of the transmission arrangement. The gear sets are situated at opposite axial ends.

[0109] The electric machines 56, 60 are arranged in axial overlap with one another. Due to the connection via intermediate gears 59, 63, high ratios for the particular gear-step gear sets are established, and so electric machines rotating at relatively high speeds are utilized, which are compact.

[0110] The hybrid transmission arrangement in the present case has precisely five forward gear steps and does not have a reverse gear step. An operation in reverse can be exclusively established by means of the hybrid drive train 10 when one of the electric machines 56, 60 is driven in the opposite direction of rotation.

[0111] The transmission arrangement 16 has no winding-path gear steps. Each gear set 36, 38, 42, 48, 50 includes precisely one idler gear and one fixed gear, wherein the idler gears of the first, second, fourth, and fifth gear sets 36, 38, 48, 50 are rotatably mounted at the output shaft 28, and wherein the idler gear of the third gear set 42 is rotatably mounted at the first input shaft 24.

[0112] Moreover, the hybrid drive train 10 includes a third clutch K3, which is also referred to as a “bridge clutch.”

[0113] The third clutch K3 is utilized for connecting the first input shaft 24 and the second input shaft 26. The third clutch K3 is arranged adjacent to the fourth gear set 48 for the second forward gear step 2 and is accommodated, with the third gearshift clutch E for the third gear set 42 for engaging the fifth forward gear step, in a third gearshift clutch assembly 66. The third clutch K3, just like the gearshift clutches A, B, C, D, E, is an unsynchronized dog clutch.

[0114] The third gearshift clutch assembly 66 is arranged coaxially to the first axis A1 and, in fact, between the third and fourth gear sets 42, 48.

[0115] The dual clutch assembly 14 and the three gearshift clutch assemblies 40, 52, 66 are actuatable by four actuating units S1, S2, S3, S4.

[0116] A first actuating unit S1 is utilized for actuating the dual clutch assembly 14 and engages either the first clutch K1 or the second clutch K2, or establishes a neutral position.

[0117] In a corresponding way, the first gearshift clutch assembly 40 is actuated by a fourth actuating unit S4. By the fourth actuating unit S4, either the first gearshift clutch A or the second gearshift clutch C is engaged, or a neutral position is established.

[0118] In a corresponding way, the second gearshift clutch assembly 52 is actuated by a third actuating unit S3 in order to either engage the fifth clutch D or the fourth clutch B, or to establish a neutral position.

[0119] Finally, the third gearshift clutch assembly 66 is engaged by a second actuating unit S2 in order to either engage the third clutch K3, or engage the third gearshift clutch E, or establish a neutral position.

[0120] In FIG. 2, a further embodiment of a hybrid drive train 10′ is represented, which generally corresponds to the drive train 10 from FIG. 1 with respect to the configuration and the mode of operation. Identical elements are therefore indicated by identical reference characters.

[0121] It is apparent that input power from the internal combustion engine 12 is guided either via the first clutch K1 to the first sub-transmission 32 or via the second clutch K2 to the second sub-transmission 34. Input power of the first electric machine 56 is supplied directly into the first sub-transmission 32 or toward the internal combustion engine 12 (for example, in order to start it) via the clutch K1.

[0122] Input power of the second electric machine 60 is introduced directly into the second sub-transmission 34 or to the internal combustion engine 12 via the clutch K2, for example, in order to start the internal combustion engine 12.

[0123] Moreover, it is apparent that the first sub-transmission 32 and the second sub-transmission 34 are connectable to each other via a third clutch K3, and so, for example, when the first clutch K1 is engaged, internal combustion engine-generated power flows via the third clutch K3 to the second sub-transmission 34.

[0124] In this case, the first electric machine 56 is switched to idle so it rotates in a nearly loss-free manner, or is operated as a generator or as an electric motor.

[0125] In a corresponding way, when the second clutch K2 is engaged, power of the internal combustion engine 12 is directed to the first sub-transmission 32 when the clutch K3 is engaged.

[0126] Moreover, a serial operation is possible when, for example, purely electric motor-generated input power from the first electric machine 56 is guided via the first sub-transmission 32 to the output shaft 28. In this case, with the first and third clutches K1, K3 disengaged, the second clutch K2 is engaged in order to utilize input power of the internal combustion engine 12 to drive the second electric machine 60 and to allow the second electric machine 60 to operate as a generator, which charges a battery (not represented in greater detail) of the drive train 10′. It is understood that all gearshift clutches of the second sub-transmission 34 are disengaged in this case.

[0127] Different operations, which are establishable with the hybrid drive train 10 from FIGS. 1 and 2, are explained with reference to FIGS. 3-5.

[0128] FIG. 3 shows a gearshift table of the shift elements K1, K2, K3, A, B, C, D, E in a purely internal combustion engine-driven operation or in a hybrid operation, in which input power is made available by the internal combustion engine and, optionally, by the electric motors.

[0129] In all forward gear steps, including a first forward gear step V1, a second forward gear step V2, a third forward gear step V3, a fourth forward gear step V4, and a fifth forward gear step V5 establishable in this operation, the first clutch K1 is continuously engaged and the second clutch K2 of the dual clutch assembly 14 is continuously disengaged. In the first forward gear step V1, the first gearshift clutch A is engaged and all other gearshift clutches B, C, D, E are disengaged. The third clutch K3 is also disengaged. Consequently, power flows from the internal combustion engine 12 via the first clutch K1 and the first input shaft 24 to the first gear set 36 and, from there, via the first gearshift clutch A to the output shaft 28.

[0130] It is understood that a driving start from a standstill generally takes place purely by electric motors 56, 60 until a speed is reached at which the internal combustion engine is connected via the first clutch K1, i.e., at a speed that corresponds to a rotational speed above the idling speed of the internal combustion engine 12. Consequently, a driving start from a standstill takes place, for example, via the first electric machine 56 and the first gear set 36 for the first forward gear step V1. As soon as a speed has been reached that corresponds to the speed of the internal combustion engine 12, the first clutch K1 is engaged. The first clutch K1 remains engaged during the entire internal combustion engine-driven operation.

[0131] During the changeover from the first forward gear step V1 into the second forward gear step V2, initially the fourth gearshift clutch B for the second forward gear step V2 is preliminarily engaged. This takes place, if necessary, with the aid of a synchronization by the second electric machine 60.

[0132] Thereafter, the first gearshift clutch A for the first forward gear step V1 is disengaged, wherein the tractive force is supported by the second electric machine 60 and the already engaged gear set 48 for the second forward gear step V2. Thereafter, the third clutch K3 is engaged, wherein the synchronization necessary takes place, on the one hand, by a rotational-speed adaptation of the internal combustion engine 12, but also by appropriate synchronization measures of the second electric machine 60. In the second forward gear step V2, power consequently flows from the internal combustion engine 12 via the first clutch K1, the first input shaft 24, the engaged third clutch K3, the second input shaft 26, and the fourth gear set 48 for the second forward gear step V2, which is engaged by the fourth gearshift clutch B, to the output shaft 28.

[0133] During the changeover into the third forward gear step V3, the third clutch K3 is disengaged, the tractive force is supported via the second electric machine 60 and, thereafter, the connecting gear step 3 is engaged in the first sub-transmission 32 by engaging the second gearshift clutch C. The necessary synchronization takes place by the first electric machine 56.

[0134] Thereafter, the load is assumed by the first electric machine 56 and the fourth gearshift clutch B of the forward gear step V2 is disengaged.

[0135] The further gear changes from the third gear step V3 to the fourth gear step V4 and from the fourth gear step V4 to the fifth gear step V5 result in a corresponding way. In each of the even forward gear steps V2, V4, the third gearshift clutch K3 is engaged. The second clutch K2 is always disengaged and the first clutch K1 is always engaged.

[0136] In FIG. 4, a purely electric motor-driven operation by the first electric machine 56 is represented. In a first electric gear step E1.1, only the first gearshift clutch A for the forward gear step V1 is engaged. In a second electric forward gear step E1.2, only the second gearshift clutch C is engaged. In a third electric-motor gear step E1.3, only the third gearshift clutch E is engaged.

[0137] In a corresponding way, FIG. 5 shows a purely electric motor-driven operation by the second electric machine 60. In a first gear step E2.1, only the fourth gearshift clutch B is engaged. In a second electric gear step E2.2, only the fifth gearshift clutch D is engaged.

[0138] In the purely electric operation according to FIGS. 4 and 5, purely electric powershifts (i.e., gear changes between forward gear steps) without, or with reduced, interruption of tractive force are possible. Here, an electric motor-driven operation is established exclusively, for example, between the gear steps E1.1, E1.2, E1.3 with the first electric machine 56 or exclusively between the gear steps E2.1, E2.2 with the second electric machine 60, and a gear change takes place while the other electric machine maintains the tractive force.

[0139] During a gear change, for example, from the forward gear step E1.1 into the forward gear step E1.2, the fourth gearshift clutch B is engaged in the second sub-transmission and, consequently, the second electric machine maintains the tractive force during the gear change in the first sub-transmission.

[0140] In the purely internal combustion engine-driven operation or hybrid operation (i.e., for the case in which internal combustion engine-generated power and, optionally, electric motor-generated power are guided to the output shaft), it is advantageous that the third clutch K3 is utilized for connecting the second input shaft 26 to the first input shaft 24 and, consequently, always supplying internal combustion engine-generated power into the transmission arrangement 16 via the first input shaft 24. Consequently, the first electric machine 56 associated with the first sub-transmission 32 is always rotationally fixed to the internal combustion engine 12 during this operation. As a result, it is possible to establish load-point displacements at the internal combustion engine 12 and the first electric machine 56 that provide assistance during the closed-loop control of the rotational speed when a synchronization process is to take place. In other words, since the first clutch K1 always remains engaged, the first electric machine 56 assists the internal combustion engine 12 during synchronization.

[0141] In order to integrate the third clutch K3, which is necessary therefor, into the transmission arrangement as efficiently as possible, the third clutch K3 is accommodated in the third gearshift clutch assembly 66. Since the third clutch K3 is integrated with a gearshift clutch into a gearshift clutch assembly that is associated with that sub-transmission, and the associated first clutch K1 of the dual clutch assembly 14, is always engaged in the internal combustion engine-driven or hybrid operation, the internal combustion engine utilizes all gear steps of the transmission.

[0142] The second clutch K2 is engaged, however, when a so-called “serial operation” is established. Here, the first clutch K1 is disengaged. Via the first sub-transmission 32 and the first electric machine 56, a purely electric motor-driven operation is established in a gear step, for example, in the forward gear step 1. The internal combustion engine 12 drives the second electric machine 60 via the engaged second clutch K2 and drives it as a generator, so the power withdrawn from a vehicle battery by the first electric machine 56 in this purely electric operation is simultaneously resupplied, at least partially, via the second electric machine 60.

[0143] A serial operation of this type is also possible in reverse when travel takes place purely electrically by the second electric machine 60 and the internal combustion engine 12 drives the first electric machine 56. In the latter case, the first clutch K1 is engaged and the second clutch K2 is disengaged.

[0144] The serial operation is utilized, in particular, in a so-called “crawling mode,” in which the vehicle speed is lower than a minimum speed that is establishable by the internal combustion engine.

[0145] The sub-transmission 32 that is associated with the first clutch K1, which is always engaged in the internal combustion engine-driven mode, preferably also includes the highest forward gear step of the transmission arrangement 16. As a result, when the third clutch K3 is disengaged, the second electric machine 60 is practically decoupled in order to avoid drag losses. In addition, the first electric machine 56 remains coupled in order to supply the main power circuit with electrical energy (operation as a generator), or in order to establish a boost operation (operation as a motor).

[0146] During a gear shift from a forward gear step of the first sub-transmission 32 into a forward gear step of the second sub-transmission 34, the desired gear step is initially engaged in the second sub-transmission by engaging the associated gearshift clutch D, B. This takes place with the aid of a synchronization by the second electric machine 60, wherein the second electric machine 60 switches over, in a load-free manner, into this target gear step in the second sub-transmission 34. Thereafter, the second electric machine 60 supports the tractive force during the gear shift via the already engaged target gear step. During the gear shift, initially the gearshift clutch of the first sub-transmission, which is associated with the starting or source gear step, disengages and, thereafter, the third clutch K3 is engaged, wherein the internal combustion engine 12 and the first electric machine 56 interact during the synchronization.

[0147] During a gear shift from the second sub-transmission 34 into a gear step of the first sub-transmission 32, the second electric machine 60 initially supports the tractive force in the source gear step or the actual gear during the gear shift. During the gear shift, the third clutch K3 is initially disengaged and one of the shift elements A, C, E engages, wherein the internal combustion engine 12 and the first electric machine 56 interact during the necessary synchronization. After the disengagement of the third clutch K3 and the load transfer on the first sub-transmission 32, the output gear step (actual gear step) in the second sub-transmission is disengaged.

[0148] It is understood that a stationary charging also takes place with the hybrid drive train when the vehicle is at a standstill. For example, the first clutch K1 is engaged and input power of the internal combustion engine 12 is supplied via the first input shaft 24 into the first electric machine 56. The second clutch K2 remains disengaged and the gearshift clutches A, C, E of the first sub-transmission 32 also remain disengaged. Therefore, the first sub-transmission 32 remains in neutral. In this condition, as mentioned, either a stationary charging takes place or a start of the internal combustion engine 12 by the first electric machine 56 takes place.

[0149] In general, it is also conceivable to engage both the first and second clutches K1, K2 or to engage the first clutch K1 and the third clutch K3 in order to allow a charging process to take place by the first electric machine 56 and also by the second electric machine 60. In this case, the internal combustion engine drives both electric machines and they both operate as generators, in order to charge a vehicle battery.

[0150] In FIG. 6, a dual-clutch assembly 14 is shown, which is usable as the dual-clutch assembly 14 of the hybrid drive train from FIG. 1.

[0151] In the dual-clutch assembly 14, the first clutch K1 is a friction-locking clutch, in particular a multi-disk clutch. The second clutch K2, however, is a form-locking clutch, in particular a non-synchronized dog clutch.

[0152] The input element EG, which is common to the two clutches K1, K2, is rotationally fixed to an outer disk carrier 80 of the first clutch K1. An inner disk carrier 82 of the first clutch K1 is rotationally fixed to the first input shaft 24. A disk pack 84 is formed between the outer disk carrier 80 and the inner disk carrier 82, which is compressible by a piston 86 in order to engage the first clutch K1. The first clutch K1 is preferably a normally disengaged clutch, which is always disengaged in the unloaded condition by a return spring force.

[0153] The clutch assembly 14 includes a single sliding element 88. The sliding element 88 is displaced into three different axial positions, into a first engagement position X1 for engaging the first clutch K1, into a second engagement position X2 for engaging the second clutch K2, and into a neutral position N situated axially therebetween.

[0154] The second clutch K2 includes an axial clutch spline 90, which is arranged at the second output element AG2. Moreover, the second clutch K2 includes an axial clutch spline 94 at the sliding element 88. The sliding element 88 is rotationally fixed to the input element EG, for example, via an axial spline (not represented in greater detail). Starting from the neutral position N represented in FIG. 6, the sliding element 88 is movable to the right by a single actuating unit S1 in order to bring the splines 90, 94 into engagement and engage the second clutch K2 in a form-locking manner. Starting from the neutral position represented in FIG. 6, the sliding element 88 is also movable in the direction of the second engagement position X1, in which an axial load is applied by the sliding element 88 onto the piston 86 in order to compress the disk pack 84.

[0155] It is understood that the first engagement position X1 is not a fixed position, but rather the first clutch K1, due to its friction-locking function, is acted upon by an axial load via the sliding element 88. The term “first engagement position” therefore corresponds, for the first clutch K1, to a position, in which a sufficient axial contact pressure is applied by the piston 86 in order to establish a friction-locking connection in the first clutch K1.

[0156] The sliding element 88 includes a synchronizer sleeve groove 96 known, per se, into which the first actuating unit S1 engages. The first actuating unit S1 is, for example, a selector fork or a swing fork, which is axially coupled to an axially displaceable shift rail (not represented). Such a shift rail is axially displaced by a suitable actuator, in order to establish the positions X1, X2, N.

[0157] In FIG. 7, a further embodiment of a dual-clutch assembly 14′ is shown, which generally corresponds to the dual-clutch assembly 14 from FIG. 6 with respect to configuration and mode of operation. Identical elements are therefore labeled with identical reference characters. In the following, essentially, the differences are explained.

[0158] It is apparent, on the one hand, that, in the dual-clutch assembly 14′ from FIG. 7, the piston 86 is coupled to the input element EG in a rotationally fixed manner and, in particular, in the area of the outer disk carrier 80. The piston 86 is rotationally fixed to the sliding element 88, which, in the dual-clutch assembly 14′, is axially displaceably and rotatably mounted at an outer circumference of the first input shaft 24.

[0159] The clutch spline 90 is formed at an axial end of a shaft stub, which forms the second output element AG2. The second output element AG2 is rigidly connected to the second input shaft 26, which, as a hollow shaft, is arranged around the first input shaft 24.

[0160] The clutch spline 90 is formed at an outer circumference of this shaft stub.

[0161] On the other hand, the sliding element 88 includes the clutch spline 94 in the area of an inner circumference of an axial projection such that the clutch spline 94 is slid onto the clutch spline 90 during the establishment of the second engagement position X2.

[0162] The sliding element 88 has a first shoulder 98, which is rigidly connected to the sliding element 88 and forms a portion of the synchronizer sleeve groove 96 and, particularly, the axial portion, by which an actuating unit S1 (not shown in greater detail in FIG. 7) applies an axial load onto the sliding element 88 in order to move the sliding element 88 into the second engagement position X2.

[0163] On the other hand, the sliding element 88 has a second shoulder 102 and an axial bearing 100. The axial bearing 100 includes a bearing element, which forms a portion of the synchronizer sleeve groove 96, and a further element, which rests against the second shoulder 102. The actuating unit S1 engaging into the synchronizer sleeve groove 96 therefore applies an axial load via this axial bearing 100 onto the sliding element 88 and, consequently, onto the piston 86 in order to engage the first clutch K1.

[0164] Modifications and variations can be made to the embodiments illustrated or described herein without departing from the scope and spirit of the invention as set forth in the appended claims. In the claims, reference characters corresponding to elements recited in the detailed description and the drawings may be recited. Such reference characters are enclosed within parentheses and are provided as an aid for reference to example embodiments described in the detailed description and the drawings. Such reference characters are provided for convenience only and have no effect on the scope of the claims. In particular, such reference characters are not intended to limit the claims to the particular example embodiments described in the detailed description and the drawings.

REFERENCE CHARACTERS

[0165] 10 hybrid drive train

[0166] 12 internal combustion engine

[0167] 14 clutch assembly

[0168] 16 hybrid transmission arrangement

[0169] 18 power distribution unit

[0170] 20 driven wheels

[0171] 22 control device

[0172] 24 first input shaft

[0173] 26 second input shaft

[0174] 28 output shaft

[0175] 30 output gear set

[0176] 32 first sub-transmission

[0177] 34 second sub-transmission

[0178] 36 first gear set (first forward gear step 1)

[0179] 38 second gear set (third forward gear step 3)

[0180] 40 first gearshift clutch assembly

[0181] 42 third gear set (fifth forward gear step 5)

[0182] 48 fourth gear set (second forward gear step 2)

[0183] 50 fifth gear set (fourth forward gear step 4)

[0184] 52 second gearshift clutch assembly

[0185] 56 first electric machine

[0186] 58 first pinion (first machine pinion)

[0187] 59 first intermediate gear

[0188] 60 second electric machine

[0189] 62 second pinion (second machine pinion)

[0190] 63 second intermediate gear

[0191] 66 third gearshift clutch assembly

[0192] 70 first gearwheel (first machine gearwheel)

[0193] 72 second gearwheel (second machine gearwheel)

[0194] A1 first axis

[0195] A2 second axis

[0196] A3 third axis

[0197] A4 fourth axis

[0198] A5 fifth axis

[0199] A first gearshift clutch

[0200] B fourth gearshift clutch

[0201] C second gearshift clutch

[0202] D fifth gearshift clutch

[0203] E third gearshift clutch

[0204] K1 first clutch of clutch assembly

[0205] K2 second clutch of clutch assembly

[0206] EG input element

[0207] AG1 first output element

[0208] AG2 second output element

[0209] K3 third clutch

[0210] S1-S4 actuating units

[0211] P parking interlock gear

[0212] 80 outer disk carrier

[0213] 82 inner disk carrier

[0214] 84 disk pack

[0215] 86 piston

[0216] 88 sliding element

[0217] 90 clutch spline (26)

[0218] 94 clutch spline (88)

[0219] 96 synchronizer sleeve groove for S1

[0220] 98 1st shoulder

[0221] 100 axial bearing

[0222] 102 2nd shoulder

[0223] 104 housing

[0224] X1 engagement position K1

[0225] X2 engagement position K2

[0226] N neutral position