METHOD FOR OPERATING A DUAL CLUTCH TRANSMISSION OF A MOTOR VEHICLE AND MOTOR VEHICLE

Abstract

A method for operating a dual clutch transmission of a motor vehicle having a first partial transmission, a second partial transmission, and a transmission output shaft common to the partial transmissions and drivable both by the first partial transmission and by the second partial transmission, in which the dual clutch transmission is in a parking lock state in which two gears of one of the partial transmissions are engaged simultaneously. The following steps are carried out to exit the parking lock state: Introducing a torque caused by a drive element of the motor vehicle via the transmission output shaft common to the one partial transmissions into the one and/or other partial transmission while the gears of the partial transmission are engaged; and disengaging at least one of the gears of the one partial transmission engaged simultaneously in step a).

Claims

1-12. (Canceled)

13. A method for operating a dual clutch transmission of a motor vehicle having a first partial transmission, a second partial transmission, and a transmission output shaft which is common to the first partial transmissions and can be driven both by the first partial transmission and by the second partial transmission, in which the dual clutch transmission is in a parking lock state in which two gears of one of the partial transmissions are engaged simultaneously, wherein to exit the parking lock state, the following steps must be performed: a) introducing a torque caused by a drive element of the motor vehicle via the transmission output shaft common to the partial transmission into the first and second partial transmission while the gears of the first partial transmission are engaged; and b) disengaging at least one of the gears of the first partial transmission engaged simultaneously in step a).

14. The method according to claim 13, wherein an electric machine is used as the drive element.

15. The method according to claim 13, wherein in step b), the at least one gear is disengaged while the other gear engaged in step a) remains engaged.

16. The method according to claim 13, wherein the method is carried out with the motor vehicle at a standstill.

17. The method according to claim 15, wherein the other gear which re-mains engaged in step b) is used for a start-up of the motor vehicle following the standstill and the termination of the parking lock state.

18. The method according to claim 17, wherein for starting the motor vehicle, the motor vehicle is driven by a drive motor provided in addition to the drive element.

19. The method according to claim 13, wherein the torque is provided and introduced into the first and second partial transmission in such a way that a movement of the motor vehicle in the longitudinal direction of the vehicle caused by the provision and introduction of the torque is prevented.

20. The method according to claim 13, wherein the torque is provided and introduced into the first and second partial transmission in such a way that the torque counteracts a slope output torque caused by a slope output force acting on the motor vehicle and introduced into the one and the other partial trans-mission.

21. The method according to claim 13, wherein in step b) both, in particular all, gears of first partial transmission are disengaged, the clutch associated with the first partial transmission is opened, a gear of the second partial transmission is engaged, and the clutch associated with the second partial transmission is closed.

22. The method according to claim 13, wherein in step b), the at least one gear is disengaged while the other gear engaged in step a) remains engaged.

23. The method according to claim 14, wherein the method is carried out with the motor vehicle at a standstill.

24. The method according to claim 15, wherein the method is carried out with the motor vehicle at a standstill.

25. The method according to claim 16, wherein the other gear which remains engaged in step b) is used for a start-up of the motor vehicle following the standstill and the termination of the parking lock state.

26. The method according to claim 14, wherein the torque is provided and introduced into the first and second partial transmission in such a way that a movement of the motor vehicle in the longitudinal direction of the vehicle caused by the provision and introduction of the torque is prevented.

27. The method according to claim 16, wherein the torque is provided and introduced into the first and second partial transmission in such a way that a movement of the motor vehicle in the longitudinal direction of the vehicle caused by the provision and introduction of the torque is prevented.

28. The method according to claim 17, wherein the torque is provided and introduced into the first and second partial transmission in such a way that a movement of the motor vehicle in the longitudinal direction of the vehicle caused by the provision and introduction of the torque is prevented.

29. The method according to claim 18, wherein the torque is provided and introduced into the first and second partial transmission in such a way that a movement of the motor vehicle in the longitudinal direction of the vehicle caused by the provision and introduction of the torque is prevented.

30. The method according to claim 19, wherein the torque is provided and introduced into the first and second partial transmission in such a way that a movement of the motor vehicle in the longitudinal direction of the vehicle caused by the provision and introduction of the torque is prevented.

31. The method according to claim 14, wherein the torque is provided and introduced into the first and second partial transmission in such a way that the torque counteracts a slope output torque caused by a slope output force acting on the motor vehicle and introduced into the one and the other partial trans-mission.

32. The method according to claim 15, wherein the torque is provided and introduced into the first and second partial transmission in such a way that the torque counteracts a slope output torque caused by a slope output force acting on the motor vehicle and introduced into the one and the other partial trans-mission.

Description

BRIEF DESCRIPTION OF THE FIGURE

[0034] An exemplary embodiment of the invention is described below. For this purpose, the only FIG. shows a schematic representation of a dual clutch transmission of a motor vehicle, wherein the dual clutch transmission is operated according to a method according to the invention.

DETAILED DESCRIPTION OF THE FIGURE

[0035] The embodiment explained below is a preferred exemplary embodiment of the invention. In the exemplary embodiment, the described components of the embodiment each represent individual features of the invention that are to be considered independently of one another, and which also each independently further develop the invention. Therefore, the disclosure is intended to include combinations of the features of the embodiment other than those shown. Furthermore, the described embodiment can also be supplemented by further of the already described features of the invention.

[0036] The only FIG. shows in a schematic representation a dual clutch transmission 10 of a motor vehicle, which is preferably designed as a motor vehicle or preferably as a passenger car. The motor vehicle has at least one drive motor 12 by means of which at least two wheels of the motor vehicle can be driven via the dual clutch transmission 10. By driving the wheels, the motor vehicle as a whole can be driven. The wheels are ground contact elements by means of which the motor vehicle can be supported or braced against a floor in the upward direction of the vehicle. The wheels are also called vehicle wheels and roll on the ground when the motor vehicle is driven along the ground, while it is supported via the wheels downward on the ground in the upward direction of the vehicle. The drive motor 12 is preferably an internal combustion engine designed, for example, as a reciprocating engine, which has an output shaft 14 designed, for example, as a crankshaft. Via the output shaft 14, the drive motor 12 can provide drive torques, which are also referred to as input torques. By means of the drive torques, the wheels can be driven via the dual clutch transmission 10, allowing the motor vehicle to be driven as a whole.

[0037] The dual clutch transmission 10 includes a first partial transmission 16 that includes, for example, three first gears 18a-c. In addition, the first partial transmission 16 includes a first transmission input shaft 20. The dual clutch transmission 10 further includes a second partial transmission 22 having a second transmission input shaft 24 and second gears 26a-c. For example, the gears 18a-c are odd gears or are also referred to as odd gears, wherein, for example, the gear 18a may be the so-called first gear, the gear 18b may be the so-called third gear, and the gear 18c may be the so-called fifth gear of the dual clutch transmission 10. For example, the gears 26a-c are also referred to as straight gears or are so-called straight gears of the dual clutch transmission 10, where, for example, the gear 26a may be the second gear, the gear 26b may be the fourth gear, and the gear 26c may be the sixth gear of the dual clutch transmission 10.

[0038] In this context, the dual clutch transmission 10 has also a first clutch 28 which is assigned to the partial transmission 16 and which is assigned, for example with respect to the partial transmissions 16 and 22, in particular with respect to the transmission input shafts 20 and 24, exclusively to the partial transmission 16 or exclusively to the transmission input shaft 20, but not to the partial transmission 22 and not to the transmission input shaft 24. The dual clutch transmission 10 further comprises a second clutch 30 which is assigned to the partial transmission 22 and which, for example with respect to the partial transmissions 16 and 22, in particular with respect to the transmission input shafts 20 and 24, is assigned exclusively to the partial transmission 22 or exclusively to the transmission input shaft 24, but not to the partial transmission 16 or not to the transmission input shaft 20. This means that, with respect to the transmission input shafts 20 and 24, only the transmission input shaft 20 can be connected or coupled to the output shaft 14 by means of the coupling 28 in a torque-transmitting manner. By means of the coupling 30, only the transmission input shaft 24 can be connected or coupled to the output shaft 14 in a torque-transmitting manner with respect to the transmission input shafts 20 and 24. In addition, the transmission input shaft 24 is designed as a hollow shaft, which in the present case is penetrated at least partially, in particular at least predominantly or completely, by the transmission input shaft 20, which is designed, for example, as a solid shaft. The respective partial transmission 16 or 22 also has a respective side shaft 32 or 34. The side shaft 32 is a first partial transmission output shaft of the partial transmission 16, as the partial transmission 16 can provide drive torques to drive the wheels via its first partial transmission output shaft. The side shaft 34 is a second partial transmission output shaft of the partial transmission 22, as the partial transmission 22 can provide torque to drive the wheels via its second partial transmission output shaft.

[0039] Furthermore, the dual clutch transmission 10 has a transmission output shaft 36 common to the partial transmissions 16 and 20, in particular the side shafts 32 and 34, which can be driven by the side shafts 32 and 34 and thus by both partial transmissions 16 and 22. For this purpose, the transmission output shaft 36 is coupled to the side shafts 32 and 34 via respective gearwheels or gearwheel pairs in a torque-transmitting manner, in particular simultaneously. Overall, it can be seen that the transmission output shaft 36 is arranged on an output side, also referred to as the exit side, of the dual clutch transmission 10, since the dual clutch transmission 10 as a whole can provide input torques for driving the wheels via the transmission output shaft 36 and thus on the output side.

[0040] The drive motor 12 can provide at least one drive torque via its output shaft 14, which can be introduced into the respective partial transmission 16 or 22 via the respective clutch 28 or 30 and can be transmitted to the transmission output shaft 36 via this. In this way, the aforementioned wheels can be driven by the drive motor 12 via the dual clutch transmission 10. Preferably, when the coupling 28 is closed, the coupling 30 is provided to be open. It is also preferred that when the coupling 30 is closed, the coupling 28 is open. Thus, preferably only one of the partial transmissions 16 and 22 is connected to the output shaft 14 via the respective coupling 28 or 30 in a torque-transmitting manner.

[0041] A method for operating the dual clutch transmission 10 is described below. In the method, the dual clutch transmission 10 is at least temporarily in a parking lock state in which, for example, the gears 18a and 18b of the partial transmission 16 are engaged simultaneously and preferably the clutch 28 is closed. Preferably, in the parking lock state, the clutch 30 is open and/or preferably, in the parking lock state, the or all gears 26a-c of the partial transmission 22 are disengaged. In addition, it is preferably provided that, except for the two engaged gears 18a and 18b, all other gears of the partial transmission 16 are disengaged. In the parking lock state, a mechanical parking lock is activated or realized, which can be used to prevent the vehicle from rolling away, especially when it is parked on a slope. In particular, when the motor vehicle is parked on the or a slope, a slope output force resulting from the weight of the motor vehicle acts on the motor vehicle. This slope output force results in a slope output torque which, for example in the parking lock state, is introduced via the wheels and the transmission output shaft 36 into the dual clutch transmission 10, in particular into the partial transmission 16, and thus acts on the dual clutch transmission 10, in particular on the partial transmission 16. Since, for example, the gears 18a, b are engaged at the same time, the partial transmission 16 is braced. In other words, the slope output torque acts as a bracing torque by which the partial transmission 16 is braced. This realizes and activates the aforementioned mechanical parking lock.

[0042] In order to be able to realize a particularly convenient operation of the motor vehicle, in order to end the parking lock state in a first step of the method, a torque produced or provided by a drive element 38 of the motor vehicle is exerted on the transmission output shaft 36 and is subsequently introduced via the transmission output shaft 36 into the locked partial transmission 16 and, if applicable, into the partial transmission 22, while the gears 18a, b of the partial transmission 16 are engaged and preferably the clutch 28 assigned to the partial transmission 16 is closed. In a second step of the method, at least one of the gears 18a, b of the partial transmission 16 engaged in the first step is disengaged—in particular after the introduction of the torque into the partial transmission 16 has begun and preferably while the torque is being introduced into the partial transmission 16—while or wherein, for example, disengagement of the respective other gear 18b or 18a is omitted. In this case, the torque is for example provided and introduced in the partial transmission 16 or 22 in such a way that the torque counteracts the slope output torque. This at least reduces or eliminates the slope output torque. In other words, this at least reduces or eliminates the previously described tension on the partial transmission 16, so that the at least one gear 18a or 18b can be designed without causing excessive jerk, also referred to as unloading jerk. For example, in the embodiment shown in the FIG., the at least one gear that is designed in the second step is gear 18a. By disengaging the at least one gear 18a or 18b, the mechanical parking lock is deactivated, i.e., disengaged. Since the tension of the partial transmission 16 is or was at least reduced or removed beforehand, the parking lock can be deactivated without causing a jerk that can be perceived by occupants in the passenger compartment of the motor vehicle. It is further preferred that the torque is provided and introduced into the partial transmission 16 or 22 in such a way that a movement of the motor vehicle in the longitudinal direction of the vehicle caused by the provision and introduction of the torque is prevented.

[0043] It can be seen from FIG. that the drive element 38 is a component provided in addition to the drive motor 12 and external with respect to the drive motor 12. While the drive motor 12 is arranged on the input side of the double clutch transmission 10, since the drive torques provided by the drive motor 12 via the output shaft 14 can be introduced into the double clutch transmission 10 on or via an input side of the double clutch transmission 10 and thereby onto the respective transmission input shaft 20 or 24, the drive element 38 is arranged on the output side of the double clutch transmission 10, i.e., on the aforementioned output side or exit side of the double clutch transmission 10.

[0044] In the embodiment shown in the FIG., the drive element 38 is an electric machine, which includes a stator 40 and a rotor 42. The rotor 42 is drivable by the stator 40 and thereby rotatable about a machine axis of rotation, particularly relative to a housing of the dual clutch transmission 10 not shown in the FIG. Here, the transmission input shafts 20 and 24 and the side shafts 32 and 34 are each at least partially arranged in said housing. In this regard, the transmission output shaft 36 is rotatable about an axis of rotation relative to the housing.

[0045] In the embodiment shown in the FIG. the machine rotation axis coincides with the rotation axis so that the drive element 38, in particular the rotor 42, is arranged coaxially with the transmission output shaft 36. In addition, the rotor 42 is disposed on the transmission output shaft 36. In particular, it is conceivable that the rotor 42 is couplable or coupled to the transmission output shaft 36 in a torque transmitting manner. In particular, it is conceivable that the rotor 42 is non-rotatably connected to the transmission output shaft 36.

[0046] For example, in the second step, the gear 18a is disengaged while the other gear 18b engaged in the first step remains engaged. The first step and the second step are performed, for example, while the motor vehicle is stationary. In this context, it has been shown to be particularly advantageous if the other gear 18b, which remains engaged during the second step, is used for a start-up of the motor vehicle following the standstill and the termination of the parking lock state.

[0047] Furthermore, it is conceivable that both gears 18a and 18b are disengaged during the second step. In addition, for example, the clutch 28 associated with the partial transmission 16 is opened. In addition, for example, at least or exactly one of the gears 26a-c of the partial transmission 22 is engaged, and the clutch 30 associated with the other partial transmission 22 is closed. Then, for example, the one gear 26a, b, and c, respectively, of the partial transmission 22 is used to drive and eventually start the motor vehicle. This driving and starting of the motor vehicle, in particular via the one engaged gear 26a, b or c and the associated clutch 30, takes place, for example, by means of the drive motor 12.

[0048] Overall, it can be seen that the parking lock described above can be implemented in a particularly space-saving, weight-saving and cost-effective manner, since the gears 18a, b that are used anyway are used to implement the mechanical parking lock. In addition, the method makes it possible to deactivate the parking lock conveniently and thus quietly, in particular noiselessly, since the torque is introduced into the partial transmission 16 or 22 beforehand.

[0049] The drive element 38, preferably in the form of an electric machine, can provide the torque, in particular as a drive torque, using electrical energy or electrical current. Thus, the electric machine provides the torque to unlock the partial transmission 16. The electric machine, in particular the rotor 42, can be connected or is connected with the transmission output shaft 36 in a rotationally fixed manner, for example, so that the drive element 38 can exert the torque, in particular directly, on the transmission output shaft 36. It is conceivable that the rotor 42 can be driven and thus rotated by the stator 40 about the axis of rotation of the machine in a first direction of rotation and in a second direction of rotation opposite to the first direction of rotation. Thus, for example, the electric machine can selectively rotate its rotor 42 and thus the transmission output shaft 36 in the first direction of rotation and in the second direction of rotation, so that the electric machine can selectively provide the torque in the first direction of rotation or in the second direction of rotation or apply the torque to the transmission output shaft 36, to unlock the partial transmission 16.

[0050] The gears 18a, b are also referred to as blocking gears. It is conceivable that the locking gears can be activated, i.e., engaged and disengaged, independently of each other.