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

Abstract

A drive train (10) for a motor vehicle includes a dual-clutch assembly (14) with a first clutch (K1) and a second clutch (K2), which include a shared input element (EG). The dual-clutch assembly (14) is connectable to an internal combustion engine (12). The first clutch (K1) includes a first output element (AG1), and the second clutch (K2) includes a second output element (AG2). A first actuating unit (S1) is associated with the first clutch (K1), and a second actuating unit (S2) is associated with the second clutch (K2). A transmission arrangement (16) includes a first sub-transmission (32) and a second sub-transmission (34). An input shaft (24) of the first sub-transmission (32) is connected to the first output element (AG1), and an input shaft (26) of the second sub-transmission (34) is connected to the second output element (AG2). The second actuating unit (S2) is associated with the second clutch (K2) of the dual-clutch assembly (14) as well as with a gearshift clutch (C; E) of the first sub-transmission (32), and/or the first actuating unit (S1″) is associated with the first clutch (K1) of the dual-clutch assembly (14) as well as with a gearshift clutch (F) of the second sub-transmission (34).

Claims

1-12: (canceled)

13. A drive train (10) for a motor vehicle, comprising: a dual-clutch assembly (14) with a first clutch (K1) and a second clutch (K2), the first and second clutches (K1, K2) having a shared input element (EG) connectable to an internal combustion engine (12), the first clutch (K1) comprising a first output element (AG1), the second clutch (K2) comprising a second output element (AG2), a first actuating unit (S1) associated with the first clutch (K1), a second actuating unit (S2) associated with the second clutch (K2); and a transmission arrangement (16) with a first sub-transmission (32) and a second sub-transmission (34), an input shaft (24) of the first sub-transmission (32) connected to the first output element (AG1), an input shaft (26) of the second sub-transmission (34) connected to the second output element (AG2), wherein one or both of the second actuating unit (S2) is associated with the second clutch (K2) of the dual-clutch assembly (14) as well as a gearshift clutch (C; E) of the first sub-transmission (32), and the first actuating unit (S1″) is associated with the first clutch (K1) of the dual-clutch assembly (14) as well as a gearshift clutch (F) of the second sub-transmission (34).

14. The drive train of claim 13, 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).

15. The drive train of claim 13, wherein one or more of the first clutch (K1) of the dual-clutch assembly (14), the second clutch (K2) of the dual-clutch assembly (14), and at least one gearshift clutch (A;B;C;D;E) of the transmission arrangement (16) is a dog clutch.

16. The drive train of claim 14, wherein one or both of: the first electric machine (56) is connected to the first input shaft (24) via a gear-step gear set (42; 38″) of the first sub-transmission (32); and 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).

17. The drive train of claim 16, wherein one or both of: the gear-step gear set (42) of the first sub-transmission (32) is associated with a highest gear step (5) of the first sub-transmission (32); and the gear-step gear set (50) of the second sub-transmission (34) is associated with a highest or a second-highest gear step (4) of the second sub-transmission (34).

18. The drive train of claim 16, wherein one or both of: the gear-step gear set (42; 38′) of the first sub-transmission (32) is arranged at a first axial end of the transmission arrangement (16); and the gear-step gear set (50) of the second sub-transmission (34) is arranged at a second axial end of the transmission arrangement (16).

19. The drive train of claim 13, wherein one or both of: the first sub-transmission (32) is associated with odd forward gear steps and has three gear sets (36, 38, 2), each of which is associated with a respective one of the odd forward gear steps (1, 3, 5); and the second sub-transmission (34) is associated with even forward gear steps and has two or three gear sets (48, 50; 48, 50, 76), each of which is associated with a respective one of the even forward gear steps (2, 4; 2, 4, 6).

20. The drive train of claim 14, wherein the first electric machine (56) and the second electric machine (60) are identical.

21. The drive train of claim 13, wherein a coupling of the actuating unit to one of the first and second clutches (K2; K1) of the dual-clutch assembly (14) to the respective one of the gearshift clutches (C; E; F) of the first and second sub-transmissions (34; 32) is configured such that either: the respective one of the gearshift clutches (C; E; F) of the first and second sub-transmissions (34; 32) is engaged; or the one of the first and second clutches (K2; K1) of the dual-clutch assembly (14) is engaged; or a neutral position is established, in which both the respective one of the gearshift clutches (C; E; F) of the first and second sub-transmissions (34; 32) and the one of the first and second clutches (K2; K1) of the dual-clutch assembly (14) are disengaged.

22. A method for operating the drive train (10) of claim 13, comprising: operating in a condition with one of the first and second clutches (K1, K2) engaged, the other of the first and second clutches (K1, K2) disengaged, and input power is transmitted via the engaged one of the first and second clutches (K1, K2); disengaging all gearshift clutches of the one of the first and second sub-transmissions (34) associated with the other of the first and second clutches (K1, K2), if necessary; synchronizing a rotational speed of the input shaft (26) associated with the other of the first and second clutches (K1, K2) with the one of the first and second electric machines (60) associated with the other of the first and second clutches (K1, K2); and engaging the other of the first and second clutches (K1, K2).

23. The method of claim 22, further comprising: after engaging the other of the first and second clutches (K1, K2), disengaging the one of the first and second clutches (K1, K2); and engaging a gearshift clutch (B; D) in the one of the first and second sub-transmission (34) associated with the other of the first and second clutches (K1, K2), wherein one or both of the engagement of the gearshift clutch (B; D) in the one of the first and second sub-transmission (34) associated with the other of the first and second clutches (K1, K2) is supported by a respective one of a first and second electric machines (56) associated with the one of the first and second clutches (K1, K2), and before the engagement of the gearshift clutch (B; D) in the one of the first and second sub-transmission (34) associated with the other of the first and second clutches (K1, K2), the gearshift clutch (B; D) in the one of the first and second sub-transmission (34) associated with the other of the first and second clutches (K1, K2) is synchronized by the other one of the first and second electric machines (60) associated with the other of the first and second clutches (K1, K2).

24. A method for operating the drive train (10) of claim 13, comprising: in a purely electric motor-driven operation, providing input power of a first electric machine (56) via the first sub-transmission (32) and simultaneously providing input power of a second electric machine (60) via the second sub-transmission (34); and implementing a powershift such that one of the first and second electric machines (56, 60) maintains tractive force via the respective one of the first and second sub-transmissions (32, 34) while a gear change is carried out in the other one of the first and second sub-transmissions (32, 34).

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0066] Exemplary embodiments of the invention are represented in the drawings and are explained in greater detail in the following description, wherein:

[0067] FIG. 1 shows a diagrammatic gear set representation of an example embodiment of a hybrid drive train;

[0068] FIG. 2 shows a gearshift table for an internal combustion engine-driven operation and a hybrid operation of the hybrid drive train from FIG. 1;

[0069] FIG. 3 shows a gearshift table for an electric motor-driven operation by the first electric machine; and

[0070] FIG. 4 shows a gearshift table for an electric motor-driven operation by the second electric machine;

[0071] FIG. 5 shows a schematic of a further example embodiment of a hybrid drive train; and

[0072] FIG. 6 shows a schematic of a further example embodiment of a hybrid drive train.

DETAILED DESCRIPTION

[0073] 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.

[0074] In FIG. 1, a hybrid drive train for a motor vehicle, in particular a passenger car, is represented in diagrammatic form and is labeled, in general, with 10. 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 can be designed, for example, as a mechanical differential and can distribute the input power to two driven wheels 20L, 20R of the motor vehicle.

[0075] Moreover, the hybrid drive train 10 includes a control device 22 for controlling all components thereof.

[0076] The dual-clutch assembly 14 is arranged on an axis A1, which is coaxial to a crankshaft of the internal combustion engine 12. The dual-clutch assembly 14 can include two friction clutches or one friction clutch and a non-synchronized dog clutch. In the present case, the dual-clutch assembly 14 contains two non-synchronized dog clutches K1 and 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 each other.

[0077] 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 each other and to the axis A1. The first input shaft 24 is designed as an inner shaft. The second input shaft 26 is designed as a hollow shaft.

[0078] Moreover, the transmission arrangement 16 includes a countershaft 28, which is designed as 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 an axis A3.

[0079] A parking interlock gear can be fixed at the output shaft 28 or at an input element of the power distribution unit 18 in a rotationally fixed manner, by which the hybrid drive train 10 can be immobilized. The associated parking lock device is not represented, for the sake of clarity.

[0080] 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 each other. 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 have a plurality of engageable gear sets, which, in the engaged condition, connect an input shaft and the output shaft 28 in each case.

[0081] The first sub-transmission 32 has a first gear set 36 for the first forward gear step 1 and a second gear set 38 for the third forward gear step 3. The second gear set 38 is arranged closer to the second axial end of the transmission arrangement 16 than the first gear set 36. Moreover, the first sub-transmission 32 has a third gear set 42 for the fifth forward gear step 5. The third gear set 42 is arranged closer to the first axial end of the transmission arrangement than the first gear set 36.

[0082] A first gearshift clutch assembly 40 is arranged between the first gear set 36 and the third gear set 42 and, in fact, coaxially to the 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 E for engaging the third gear set 42. The two gearshift clutches A, E are alternately engageable and are designed as non-synchronized 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.

[0083] The second gear set 38 is engageable by a gearshift clutch C and has an idler gear, which is rotatably mounted at the first input shaft 24.

[0084] The second sub-transmission 34 has a fourth gear set 48 for the second forward gear step 2 and a fifth gear set 50 for the 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 gear sets 48, 50 and, in fact, coaxially to the axis A2. The second gearshift clutch assembly 52 has a gearshift clutch B for engaging the fourth gear set 48 and a gearshift clutch D for engaging the fifth gear set 50. The gearshift clutches B and D are accommodated in the second gearshift clutch assembly 52 in such a way that the gearshift clutches B and D are alternately actuatable.

[0085] 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: gear set 50 for the fourth forward gear step 4, gear set 48 for the second forward gear step 2, gear set 38 for the third forward gear step 3, gear set 36 for the first forward gear step 1, and gear set 42 for the fifth forward gear step 5.

[0086] 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 axis A4. The first pinion 58, which can also be 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 third gear set 42 for the fifth forward gear step 5, via a first intermediate gear 59, which is 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 third gear set 42, wherein the fixed gear is rotationally fixed to the first input shaft 24.

[0087] 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 60 has a second pinion (second machine pinion) 62, which is arranged coaxially to the 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 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, which is 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, wherein the fixed gear is rotationally fixed to the second input shaft 26.

[0088] The five axes A1, A2, A3, A4, A5 are all aligned in parallel with one another.

[0089] 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 can be fixed at the output shaft 28 between the output gear set 30 and the fifth gear set 50.

[0090] In the hybrid drive train 10, the electric machines 56, 60 are each connected to a gear-step gear set of an associated sub-transmission, which is associated with the highest gear step of that sub-transmission. Moreover, the electric machines 56, 60 are each connected via a gear-step gear set to the 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.

[0091] The electric machines 56, 60 are arranged in axial overlap with each other. Due to the connection via intermediate gears 59, 63, high ratios for the particular gear-step gear sets can be established, and so electric machines 56, 60 rotating at relatively high speeds can be utilized, which are compact.

[0092] The hybrid transmission arrangement 16 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 the hybrid drive train 10 when one of the electric machines 56 or 60 is driven in the opposite direction of rotation.

[0093] The transmission arrangement 16 has no winding-path gear steps. Each gear set 36 through 50 includes precisely one idler gear and one fixed gear, wherein the idler gears of the gear sets 36, 42, 48, 50 are rotatably mounted at the output shaft 28, and wherein the idler gear of the gear set 38 is rotatably mounted at the first input shaft 24.

[0094] The dual-clutch assembly 14 and the two gearshift clutch assemblies 40, 52 and the gearshift clutch C are actuatable by four actuating units S1 through S4.

[0095] One actuating unit S1 is utilized for actuating the clutch K1 of the dual-clutch assembly 14 and can engage or disengage the clutch K1.

[0096] The first gearshift clutch assembly 40 can be actuated by a fourth actuating unit S4. By the fourth actuating unit S4, either the gearshift clutch A can be engaged, or the gearshift clutch E can be engaged, or a neutral position can be established.

[0097] In a corresponding way, the second gearshift clutch assembly 52 can be actuated by a third actuating unit S3, in order to either engage the clutch D, or engage the clutch B, or establish a neutral position.

[0098] Finally, by a second actuating unit S2, the second clutch K2 of the dual-clutch assembly 14 or the gearshift clutch C can be engaged. The second actuating unit S2 is coupled to the second clutch K2 of the dual-clutch assembly as well as to the gearshift clutch C of the first sub-transmission. The coupling is implemented in the manner of a gearshift clutch assembly in such a way that the second actuating unit S2 can also establish a neutral position, in which the second clutch K2 and the gearshift clutch C are both disengaged.

[0099] When a power transmission in the transmission arrangement 10 from FIG. 1 takes place via the first input shaft 24 and the first clutch K1 is engaged, the third actuating unit S3 is in a neutral position. In this case, each of the gearshift clutches A, E, C of the first sub-transmission can be alternately engaged. When the gearshift clutch C is engaged in order to establish the third forward gear step 3 in this operation, the second clutch K2 of the dual-clutch assembly 14 is disengaged. The second clutch K2 of the dual-clutch assembly 14 could also be engaged during the establishment of the third forward gear step 3 when the third actuating unit S3 is in the neutral position.

[0100] On the other hand, if power is to be transmitted via the second input shaft 26, the second clutch K2 is engaged by the second actuating unit S2 and the first clutch K1 is disengaged by the first actuating unit S1. Due to the engagement of the second clutch K2, the gearshift clutch C for the third forward gear step 3 is disengaged.

[0101] Different operations, which are establishable with the hybrid drive train 10 from FIG. 1, are explained with reference to FIGS. 2 through 4. The same operations are also usable with the hybrid drive trains 10′, 10″ from FIGS. 5 and 6, however.

[0102] FIG. 2 shows a gearshift table of the shift elements K1, K2, A-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 56, 60.

[0103] In all forward gear steps V1 through V5 establishable in this operation, the first clutch K1 or the second clutch K2 of the dual-clutch assembly 14 is alternately engaged. In the forward gear steps V1, V3, and V5, the first clutch K1 is engaged and the second clutch K2 is disengaged. In the forward gear steps V2 and V4, the second clutch K2 is engaged and the first clutch K1 is disengaged. In the forward gear step V1, the gearshift clutch A is additionally engaged and all other gearshift clutches B through E are disengaged. Consequently, power flows from the internal combustion engine via the first clutch K1 and the first input shaft 24 to the first gear set 36 and, from there, via the gearshift clutch A to the output shaft 28.

[0104] 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 12 can be 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 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 can be engaged.

[0105] During the changeover from the forward gear step V1 into the forward gear step V2, initially the gearshift clutch B for the forward gear step 2 is preliminarily engaged. This can take place, if necessary, with the aid of a synchronization by the second electric machine 60.

[0106] Thereafter, the gearshift clutch A for the forward gear step V1 and the first clutch K1 are disengaged, wherein the tractive force is supported by the second electric machine 60 and the already engaged gear set 48 for the forward gear step V2. Thereafter, the second clutch K2 can be engaged, wherein the synchronization necessary therefor 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, power therefore flows from the internal combustion engine 12 via the second clutch K2, the second input shaft 26, and the gear set 48 for the second forward gear step V2 engaged by the gearshift clutch B, to the output shaft 28.

[0107] During the changeover into the forward gear step V3, due to the fact that the second clutch K2 and the gearshift clutch C for the forward gear step V3 are actuated via a single actuating unit S2, the following approach is preferred. In the forward gear step V2, the second clutch K2 is engaged, and the first clutch K1 is disengaged. Initially, tractive force is supported via the second electric machine 60 and the forward gear step V2. Thereafter, the second clutch K2 can be disengaged and the gearshift clutch C can be engaged, wherein the neutral position of the second actuating unit S2 is passed through. Thereafter, the first clutch K1 can be engaged, in order to apply the power to the third forward gear step V3, and the tractive force of the second electric machine 60 can be decreased. Finally, the second gearshift clutch B of the second forward gear step V2 can be disengaged.

[0108] The further gear changes from the gear steps V3 to V4 and from V4 to V5 result in a corresponding way.

[0109] In FIG. 3, a purely electric motor-driven operation by the first electric machine is represented. In a first electric gear step E1.1, only the gearshift clutch A for the forward gear step 1 is engaged. In a second electric forward gear step E1.2, only the gearshift clutch C is engaged. In a third electric-motor gear step E1.3, the gearshift clutch E is engaged.

[0110] In a corresponding way, FIG. 4 shows a purely electric motor-driven operation by the second electric machine 60. In a first gear step E2.1, only the gearshift clutch B is engaged. In a second electric gear step E2.2, only the gearshift clutch D is engaged.

[0111] In the purely electric operation according to FIGS. 3 and 4, 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 or exclusively between the gear steps E2.1 and E2.2, and a gear change takes place while the other electric machine maintains the tractive force.

[0112] During a gear change, for example, from the forward gear step E1.1 into the forward gear step E1.2, the gearshift clutch B can be engaged in the second sub-transmission 34 and, consequently, the second electric machine 60 can maintain the tractive force during the gear change in the first sub-transmission 32.

[0113] A changeover of the two clutches K1, K2 of the dual-clutch assembly 14 preferably always takes place in such a way that at least one of the two clutches K1, K2 is always engaged. This means, both clutches K1, K2 are simultaneously engaged during the changeover.

[0114] For example, during a changeover from clutch K1 to clutch K2, the clutch K2 is initially engaged in addition to clutch K1 and, thereafter, clutch K1 is disengaged. The clutch K2 is synchronized with the second electric machine 60.

[0115] During a changeover from clutch K2 to clutch K1, the first clutch K1 is initially engaged in addition to clutch K2 and, thereafter, the second clutch K2 is disengaged. The first clutch K1 is synchronized with the first electric machine 56.

[0116] In other words, the two clutches K1 and K2 can always be synchronized with the aid of an electric machine.

[0117] During powershifts in the hybrid mode, by utilizing the internal combustion engine 12, there are two possibilities for switching from one gear (actual gear) of the first sub-transmission 32 into a gear (target gear) of the second sub-transmission 34. In one example variant, the first electric machine 56 supports the gear shift in the actual gear. This method is possible in the case of the actual gears 1 and 5, but not in the case of the actual gear 3, since the gearshift clutch C is actuated together with the second clutch K2.

[0118] Alternatively, it is possible to support the gear shift from the first sub-transmission 32 onto the second sub-transmission 34 via the second electric machine 60 in the target gear. This method is also possible in the case of the actual gear 3.

[0119] On the other hand, gear shifts from the second sub-transmission 34 into the first sub-transmission 32 can take place, in general, when the second electric machine 60 supports the tractive force in the actual gear during the gear shift.

[0120] In general, it is also conceivable to support the tractive force during the gear shift by the first electric machine 56 in the target gear. This method is possible in the case of the target gears 1 and 5, however, but not in the case of the target gear 3, for the aforementioned reason.

[0121] When travel takes place by the internal combustion engine 12 via the first clutch K1 in a gear of the first sub-transmission 32, the second electric machine 60 can be decoupled, in order to avoid drag losses. The first electric machine 56 preferably remains coupled, in order to supply a main power circuit with electrical energy and, thereby, the first electric machine 56 can additionally drive (“boost”). This is particularly important in the fifth gear (since the fifth gear is utilized for a longer time during expressway travel).

[0122] In a corresponding way, during an internal combustion engine-driven operation via the second sub-transmission 34, the first electric machine 56 can be decoupled, but the second electric machine 60 can remain coupled.

[0123] When the clutches K1 and K2 are simultaneously engaged, the internal combustion engine 12 as well as the two electric machines 56, 60 can jointly drive the first sub-transmission 32 via the first gear and the fifth gear. If recuperation takes place in the case of a deceleration, the internal combustion engine 12 and the second electric machine 60 can be decoupled by disengaging the first clutch K1. Recuperation then takes place in the actual gear of the first electric machine 56. The internal combustion engine 12 and the second electric machine 60 remain connected. If the internal combustion engine 12 is switched off, a restart can quickly take place by the second electric machine 60. Alternatively, the second electric machine 60 can also operate as a generator in this case (the internal combustion engine 12 continues to run). A coupling to the drive train 10 by engaging the first clutch K1 is quickly possible.

[0124] This operating mode is generally not possible for the third forward gear step due to the common actuating unit S2.

[0125] On the other hand, when the two clutches K1 and K2 are simultaneously engaged, the internal combustion engine 12, the first electric machine 56, and the second electric machine 60 can jointly drive via the second gear and the fourth gear of the second sub-transmission 34. If recuperation takes place in the case of a deceleration, the internal combustion engine 12 and the first electric machine 56 can be decoupled by disengaging the second clutch K2. The further possibilities are identical to the case in which driving takes place jointly via the first sub-transmission 32.

[0126] It is understood that stationary charging is possible and, in fact, by engaging, for example, the first clutch K1, in order to connect the first electric machine 56 to the internal combustion engine 12, without a force-fit connection to the output shaft 28 being established (i.e., the transmission arrangement 16 is then in neutral and all gearshift clutches A through E are disengaged). In this condition, the internal combustion engine 12 can be started with the first electric machine 56 and a supply of the main power circuit can take place by operating the first electric machine 56 as a generator and/or a charging of an electrical energy accumulator can take place.

[0127] The same operation is also possible in a corresponding way by engaging the second clutch K1.

[0128] The two clutches K1 and K2 can also be simultaneously engaged, in order to enable a generator mode with both electric machines 56, 60.

[0129] The two electric machines 56, 60 preferably have identical dimensions.

[0130] The second clutch K2 can be engaged when a 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 the second electric machine 60 as a generator, and so the power withdrawn from a vehicle battery by the first electric machine 56 in this purely electric operation can be simultaneously resupplied, at least partially, via the second electric machine 60.

[0131] 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.

[0132] The serial operation is utilized, in particular, in a crawling mode, in which the vehicle speed is lower than a minimum speed that is establishable by the internal combustion engine 12.

[0133] In FIG. 5, a further example embodiment of a hybrid drive train 10′ is represented, which generally corresponds to the drive train 10 from FIG. 1 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.

[0134] It is apparent, on the one hand, that the gear sets for the third and fifth forward gear steps 3 and 5 are interchanged in the first sub-transmission 32. Consequently, the second gear set 38′ for the third forward gear step 3 is arranged closer to the first axial end of the transmission arrangement 16 than the third gear set 42′ for the fifth forward gear step 5. A gearshift clutch E for the fifth forward gear step 5 is arranged between the gear sets 42′ and 48, at the point, at which the gearshift clutch C is arranged in the drive train 10 from FIG. 1.

[0135] Moreover, the first gearshift clutch assembly 40′ contains the gearshift clutch A for engaging the first gear set 36 for the first forward gear step 1 and the gearshift clutch C for engaging the second gear set 38′ for the third forward gear step 3.

[0136] As represented in FIG. 5, moreover, the first electric machine 56 and/or the second electric machine 60 do/does not necessarily need to be connected via a gear-step gear set to the particular associated input shaft 24, 26. Rather, it is also possible to fix a first gearwheel (first machine gearwheel) 70 at the first output shaft 24, which is in engagement with the first pinion 58 directly or via a first intermediate gear 59′.

[0137] In a corresponding way, a second gearwheel (second machine gearwheel) 72 can be fixed at the second output shaft 26, which is in engagement with the second pinion 62 directly or via a second intermediate gear 63′.

[0138] Due to the first gearwheel 70 and/or the second gearwheel 72, one additional degree of freedom can be implemented, which simplifies the implementation of the pre-ratio.

[0139] The first gearwheel 70 is preferably situated in a plane with the first gearshift clutch assembly 40′, and so this implementation is possible in a length-neutral manner. In the same way, the second gearwheel 72 is axially aligned with the second gearshift clutch assembly 52, and so the provision of the second gearwheel 72 also does not result in a lengthening of the installation space.

[0140] In particular for the case in which the gearwheels 70, 72 are not provided, but rather a connection is to take place via the gear sets that are arranged at the axial ends of the transmission arrangement 16, the following advantage can be achieved. This is the case because the first electric machine 56, as shown in FIG. 1, can be connected to the first input shaft 24 via the gear-step gear set 42 that represents the highest ratio of the first sub-transmission 32, and so a larger ratio can be implemented in the electric operation.

[0141] The latter-described example variant is considered to be particularly preferred.

[0142] In FIG. 6, a further alternative example embodiment of a hybrid drive train 10″ is shown, which generally corresponds to the drive train 10 from FIG. 1 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.

[0143] The second sub-transmission 34″ includes a further gear set 76 for a sixth forward gear step 6, which is arranged in the axial direction between the gear set 48 for the forward gear step 2 and the gearshift clutch plane with the gearshift clutch C. Moreover, the second sub-transmission 34″ includes a gearshift clutch F arranged at the output shaft 28, which is situated in the same gearshift clutch plane as the gearshift clutch C. The gearshift clutch F is associated with the gear set 76 for the forward gear step 6.

[0144] Due to this addition of a further gear set for the forward gear step 6 to the second sub-transmission 34″, the spread of gear ratios of the transmission arrangement 16 can be further increased.

[0145] Moreover, it is possible to still provide only four actuating units for actuating the drive train. These are the actuating unit S2 for the clutches K2 and C, the actuating unit S3 for the gearshift clutch assembly 52 with the gearshift clutches D and B, and the actuating unit S4 for the gearshift clutch assembly 40 with the gearshift clutches A and

[0146] E.

[0147] Moreover, an actuating unit S1″ is provided, which, similarly to the actuating unit S2, is associated with two clutches, namely the first clutch K1 of the dual-clutch assembly 14 and the gearshift clutch F for the sixth forward gear step 6.

[0148] It is understood that the sixth forward gear step 6 (V6) is established, in that the clutch K2 is engaged (which automatically results in an engagement of the gearshift clutch C).

[0149] The gearshift clutch F is engaged, in order to place the gear set 76 into the power flow. This takes place by the actuating unit S1″ and results in the first clutch K1 also being engaged.

[0150] 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

[0151] 10 hybrid drive train [0152] 12 internal combustion engine [0153] 14 dual-clutch assembly [0154] 16 hybrid transmission arrangement [0155] 18 power distribution unit [0156] 20 driven wheels [0157] 22 control device [0158] 24 first input shaft [0159] 26 second input shaft [0160] 28 output shaft [0161] 30 output gear set [0162] 32 first sub-transmission [0163] 34 second sub-transmission [0164] 36 1st gear set (1) [0165] 38 2nd gear set (3) [0166] 40 first gearshift clutch assembly [0167] 42 3rd gear set (5) [0168] 48 4th gear set (2) [0169] 50 5th gear set (4) [0170] 52 second gearshift clutch assembly [0171] 56 first electric machine [0172] 58 first pinion (first machine pinion) [0173] 59 first intermediate gear [0174] 60 second electric machine [0175] 62 second pinion (second machine pinion) [0176] 63 second intermediate gear [0177] 66 third gearshift clutch assembly [0178] 70 first gearwheel (first machine gearwheel) [0179] 72 second gearwheel (second machine gearwheel) [0180] 76 gear set (6) [0181] A1-A5 axes [0182] A-E, F gearshift clutches for gear steps [0183] K1, K2 clutches of dual-clutch assembly [0184] EG input element [0185] AG1 first output element [0186] AG2 second output element [0187] S1-S4 actuating units [0188] P parking interlock gear