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

Abstract

A method for operating a dual-clutch transmission having a first partial transmission, a second partial transmission, a first clutch assigned to the first partial transmission, and a second clutch assigned to the second partial transmission, in which the dual-clutch transmission is shifted into a parking lock state. The dual-clutch transmission is shifted into the parking lock state by the following steps: while a first gear of one of the partial transmissions is engaged: carrying out an engagement process provided for engaging a second gear of the one partial transmission; determining that the second gear is not engaged despite the engagement process being carried out; selecting a third gear of the dual-clutch transmission different from the first gear and from the second gear; and engaging the selected third gear such that in the park lock condition, the first gear and the third gear are at least temporarily engaged simultaneously.

Claims

1-10. (canceled)

11. A method for operating a dual-clutch transmission of a motor vehicle, having a first partial transmission, a second partial transmission, a first clutch as-signed to the first partial transmission, and a second clutch assigned to the second partial transmission, in which the dual-clutch transmission is switched to a parking lock state, wherein the dual-clutch transmission is shifted into the parking lock state by the following steps: while a first gear of one of the partial transmissions is engaged: carrying out an engagement process provided for engaging a second gear of the one partial transmission; determining that the second gear is not being engaged despite the engagement process being carried out; selecting a third gear of the dual-clutch transmission different from the first gear and from the second gear; and engaging the selected third gear, so that in the parking lock state, the first gear and the third gear are at least temporarily engaged simultaneously.

12. The method as claimed in claim 11, wherein the third gear is a gear of the one partial transmission.

13. The method as claimed in claim 11, wherein the third gear is a gear of the other partial transmission.

14. The method as claimed in claim 11, wherein in the parking lock state, the first gear is engaged in that a first gear wheel of the first gear, designed as an idler wheel and rotatably arranged on a first shaft of the dual-clutch transmission, is connected in a rotationally-fixed manner to the first shaft by a first shifting element, which is assigned to the first gear, is arranged on the first shaft, and is connected in a rotationally-fixed manner to the first shaft, wherein the third gear is engaged in that a second gearwheel of third gear, designed as an idler wheel and rotatably arranged on a second shaft of the dual-clutch transmission, is connect-ed in a rotationally-fixed manner to the second shaft by a second shifting element, which is assigned to the third gear, is arranged on the second shaft, and is connected in a rotationally-fixed manner to the second shaft.

15. The method as claimed in claim 14, wherein the respective shifting element is a formfitting shifting element, in particular a claw clutch.

16. The method as claimed in claim 11, wherein after engaging the third gear, the third gear is disengaged and the second gear is engaged, in particular while the first gear remains engaged.

17. The method as claimed in claim 11, wherein after engaging the third gear, the first gear is disengaged and a fourth gear of the dual-clutch transmission that differs from the first gear, the second gear and the third gear is engaged so that in the parking lock state, the third gear and the fourth gear are engaged simultaneously.

18. The method as claimed in claim 11, wherein in the parking lock state, at least or precisely one of the clutches or both clutches are closed at the same time.

19. The method as claimed in claim 11, the method is carried out when the motor vehicle is stationary.

20. A vehicle having a dual-clutch transmission which is designed to carry out a method as claimed in claim 11.

21. The method as claimed in claim 12, wherein the third gear is a gear of the other partial transmission.

22. The method as claimed in claim 12, wherein in the parking lock state, the first gear is engaged in that a first gear wheel of the first gear, designed as an idler wheel and rotatably arranged on a first shaft of the dual-clutch transmission, is connected in a rotationally-fixed manner to the first shaft by a first shifting element, which is assigned to the first gear, is arranged on the first shaft, and is connected in a rotationally-fixed manner to the first shaft, wherein the third gear is engaged in that a second gearwheel of third gear, designed as an idler wheel and rotatably arranged on a second shaft of the dual-clutch transmission, is connect-ed in a rotationally-fixed manner to the second shaft by a second shifting element, which is assigned to the third gear, is arranged on the second shaft, and is connected in a rotationally-fixed manner to the second shaft.

23. The method as claimed in claim 13, wherein in the parking lock state, the first gear is engaged in that a first gear wheel of the first gear, designed as an idler wheel and rotatably arranged on a first shaft of the dual-clutch transmission, is connected in a rotationally-fixed manner to the first shaft by a first shifting element, which is assigned to the first gear, is arranged on the first shaft, and is connected in a rotationally-fixed manner to the first shaft, wherein the third gear is engaged in that a second gearwheel of third gear, designed as an idler wheel and rotatably arranged on a second shaft of the dual-clutch transmission, is connect-ed in a rotationally-fixed manner to the second shaft by a second shifting element, which is assigned to the third gear, is arranged on the second shaft, and is connected in a rotationally-fixed manner to the second shaft.

24. The method as claimed in claim 12, wherein after engaging the third gear, the third gear is disengaged and the second gear is engaged, in particular while the first gear remains engaged.

25. The method as claimed in claim 13, wherein after engaging the third gear, the third gear is disengaged and the second gear is engaged, in particular while the first gear remains engaged.

26. The method as claimed in claim 14, wherein after engaging the third gear, the third gear is disengaged and the second gear is engaged, in particular while the first gear remains engaged.

27. The method as claimed in claim 15, wherein after engaging the third gear, the third gear is disengaged and the second gear is engaged, in particular while the first gear remains engaged.

28. The method as claimed in claim 12, wherein after engaging the third gear, the first gear is disengaged and a fourth gear of the dual-clutch transmission that differs from the first gear, the second gear and the third gear is engaged so that in the parking lock state, the third gear and the fourth gear are engaged simultaneously.

29. The method as claimed in claim 13, wherein after engaging the third gear, the first gear is disengaged and a fourth gear of the dual-clutch transmission that differs from the first gear, the second gear and the third gear is engaged so that in the parking lock state, the third gear and the fourth gear are engaged simultaneously.

30. The method as claimed in claim 14, wherein after engaging the third gear, the first gear is disengaged and a fourth gear of the dual-clutch transmission that differs from the first gear, the second gear and the third gear is engaged so that in the parking lock state, the third gear and the fourth gear are engaged simultaneously.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0029] An exemplary embodiment of the invention are described hereinafter. For this purpose, the only figure 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.

[0030] The exemplary embodiment explained hereinafter is a preferred embodiment of the invention. In the exemplary embodiment, the described components of the embodiments each represent individual features of the invention to be considered independently of one another, which each also refine the invention independently of one another. Therefore, the disclosure is also intended to encompass combinations of the features of the embodiment other than those illustrated. Furthermore, the described embodiment can also be supplemented by further ones of the above-described features of the invention.

DETAILED DESCRIPTION

[0031] The only figure shows a schematic representation of a dual-clutch transmission 10 of a motor vehicle, which is preferably designed as an automobile or preferably as a passenger vehicle. The motor vehicle has at least one drive motor, 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 can be or is driven as a whole. The wheels are ground contact elements via which the motor vehicle can be or is supported on a ground in the vehicle vertical direction downwards. The wheels, also referred to as vehicle wheels, roll on the ground when the motor vehicle is driven along the ground, while the motor vehicle is supported downwards on the ground via the wheels in the vertical direction of the vehicle. The drive motor is shown particularly schematically in the figure and is identified by 12 there. The drive motor 12 can be an internal combustion engine designed as a reciprocating piston engine, for example, or an electric machine. The drive motor 12 has an output shaft 14 designed as a crankshaft, for example.

[0032] The dual-clutch transmission 10 has a first partial transmission 16, which comprises, for example, three first gears 18a-c. In addition, the first partial transmission 16 has a first transmission input shaft 20. The dual-clutch transmission 10 also includes a second partial transmission 22, which has a second transmission input shaft 24 and second gears 26a-c. The gears 18a-c are, for example, odd gears or are also referred to as odd gears, wherein the gear 18a is the so-called first gear, the gear 18b is the so-called third gear, and the gear 18c is the so-called fifth gear of the dual-clutch transmission 10, for example. The gears 26a-c are also referred to as even gears, for example, or are so-called even gears of the dual-clutch transmission 10, wherein the gear 26a, for example, is the second gear, the gear 26b is the fourth gear, and the gear 26c is the sixth gear of the dual-clutch transmission 10. The gears 18a-c and 26a-c can also be designed as forward gears, referred to as forward driving gears, for causing a respective forward travel of the motor vehicle, or at least or exactly one of the gears 18a-c and 26a-c is a reverse gear for causing a reverse travel of the motor vehicle. The first gear is a forward starting gear, by means of which the motor vehicle can be started forward. The reverse gear is a reverse starting gear, by means of which the motor vehicle can be started in reverse.

[0033] The dual-clutch transmission 10 has a first clutch 28 assigned to the partial transmission 16, which, for example in relation to the partial transmissions 16 and 22, in particular in relation to the transmission input shafts 20 and 24, is assigned exclusively to the partial transmission 16 or exclusively to the transmission input shaft 20, but is not assigned to the partial transmission 22 and not to the transmission input shaft 24. The dual-clutch transmission 10 additionally has a second clutch 30 assigned to the partial transmission 22, which, for example in relation to the partial transmissions 16 and 20, in particular in relation 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 is not assigned to the partial transmission 16 and not to the transmission input shaft 20. This means that, with respect to the transmission input shafts 20 and 24, exclusively the transmission input shaft 24 can be connected to the output shaft 14 in a torque-transmitting manner by means of the clutch 28. With respect to the transmission input shafts 20 and 24, exclusively the transmission input shaft 24 can be connected or coupled to the output shaft 14 in a torque-transmitting manner by means of the clutch 30. 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 designed, for example, as a solid shaft. The respective partial transmission 16 or 22 also has a side shaft 32 or 34, respectively. The dual-clutch transmission 10 has a transmission output shaft 36 which is common to the partial transmissions 16 and 20, in particular the side shafts 32 and 34, and which is drivable by the side shafts 32 and 34.

[0034] The drive motor 12 can provide at least one drive torque via its output shaft 14, which can be introduced into the partial transmission 16 or 22 via the respective clutch 28 or 30 and can be transmitted via this to the transmission output shaft 36. In this way, the above-mentioned wheels can be driven by the drive motor 12 via the dual-clutch transmission 10. It is preferably provided that the clutch 30 is open when the clutch 28 is closed. It is also provided, for example, that the clutch 28 is opened when the clutch 30 is closed. Thus, preferably only one of the partial transmissions 16 and 20 is always connected to the output shaft 14 in a torque-transmitting manner via the respective clutch 28 or 30.

[0035] A method for operating the dual-clutch transmission 10 is described hereinafter. In the method, the dual-clutch transmission 10 is shifted into a parking lock state, so that in the method the dual-clutch transmission 10 is at least temporarily in the parking lock state.

[0036] In order to be able to particularly safely engage the parking lock state and thus a mechanical parking lock, by means of which, for example, the above-mentioned wheels can be secured against rotation and the motor vehicle can thereby be secured against undesired rolling away, the dual-clutch transmission 10 is shifted into the parking lock state by the following steps. In a first of the steps, while the gear 18a of the partial transmission 16 is engaged, for example, an engagement process provided for engaging the gear 18b, for example, is carried out. In a second of the steps, it is determined that the second gear 18b has not been engaged or the engagement did not take place despite the engagement process being carried out. In a third of the steps, for example, the gear 18c is selected and in a fourth of the steps, the selected gear 18c is engaged such that in the parking lock state, the gear 18a and the gear 18c are at least temporarily engaged simultaneously. It can be seen here that the gears 18a and 18c that are simultaneously engaged at least temporarily in the parking lock state are gears of the same partial transmission 16.

[0037] In the parking lock state, the gear 18a is preferably engaged in that a first gear wheel 38 of the gear 18a, designed as an idler wheel and rotatably arranged on the side shaft 32 of the dual-clutch transmission 10, in particular the partial transmission 16, is connected in a rotationally fixed manner to the side shaft 32 by means of a first shifting element 40, which is assigned to the first gear 18a, is arranged on the side shaft 32, and is connected in a rotationally fixed manner to the side shaft 32. The switching element 40 is a shifting sleeve. The gear 18c is preferably engaged in that a second gearwheel 42 of the gear 18c, designed as an idler wheel and rotatably arranged on the transmission input shaft 20 of the dual-clutch transmission 10, in particular of the partial transmission 16, is connected in a rotationally-fixed manner to the transmission input shaft 20 by means of a second shifting element 44, which is assigned to the gear 18c, is arranged on the transmission input shaft 20, and is connected in a rotationally-fixed manner to the transmission input shaft 20. The switching element 44 is preferably a second shifting sleeve. The shifting elements 40 and 44 are gear selectors, in particular formfitting gear selectors, which are moved into a respective engaged position to engage the gears 18a and 18c. As a result, the shifting element 40 is connected in a formfitting manner to the gearwheel 38 and the shifting element 44 is connected in a formfitting manner to the gearwheel 42, so that the gearwheel 38 is connected in a formfitting manner to the side shaft 32 via the shifting element 40, and the gearwheel 42 is connected in a formfitting manner to the transmission input shaft 20 via the shifting element 44. The side shaft 32 and the transmission input shaft 20 are respective shafts of the dual-clutch transmission 10, in particular of the partial transmission 16, which are different from one another and are formed separately from one another, wherein the shafts or arranged offset from one another and extend at least essentially in parallel to one another. In addition, the respective shifting element 40 or 44 is a formfitting shifting element, in particular a claw clutch, by means of which the respective gear wheel 38 or 42 is connectable or connected in a formfitting and rotationally-fixed manner to the side shaft 32 or to the transmission input shaft 20.

[0038] In principle, it is conceivable that after the gear 18c has been engaged, the gear 18c is disengaged and, for example, the gear 18b is engaged, in particular while the gear 18a remains engaged, so that in the parking lock state the gears 18a and 18b are engaged simultaneously, at least temporarily. Furthermore, it is conceivable that, in particular after the gear 18c is engaged, the first gear 18a is disengaged and a fourth gear of the dual-clutch transmission 10 that differs from the gear 18a, the gear 18b, and the gear 18c is engaged, so that in the parking lock state, for example, the gear 18c or the gear 18b and fourth gear are engaged simultaneously, at least temporarily. The fourth gear is, for example, one of the gears 26a-c and thus a gear of the partial transmission 22 or a gear of the partial transmission 16.

[0039] Overall, it can be seen that the parking lock state can also be securely activated when it is not possible to engage the gear 18b, which is actually intended as a locking gear, for example due to an unforeseen event such as an unfavorable location or position of a gear selector assigned to the gear 18b. Then, instead of the locking gear that is actually provided, the gear 18c is at least temporarily engaged, for example, in order to clamp the dual-clutch transmission 10, in particular the partial transmission 16. This clamping activates or engages a mechanical parking lock, as a result of which the motor vehicle can be secured against undesired rolling away.