WO2009047162A1

WO2009047162A1 - Method for generating braking torque in motor vehicles with a double clutch transmission

Info

Publication number: WO2009047162A1
Application number: PCT/EP2008/063060
Authority: WO
Inventors: Michael Werner; Holger Niemann; Per Hagman; Andreas Heyl
Original assignee: Robert Bosch Gmbh
Priority date: 2007-10-08
Filing date: 2008-09-30
Publication date: 2009-04-16
Also published as: DE102007048268A1

Abstract

The invention relates to a method for operating a double clutch transmission (3) in on a motor vehicle wherein, in order to generate a braking torque, the clutch member (8, 9) of one of the two gear trains (6, 7) of the double clutch transmission (3) is brought into a slipping position in which the clutch components (8a, 8b, 9a, 9b) are in a torque or power transmitting position, but carry out a movement relative to each other.

Description

title

Method for braking torque generation in motor vehicles with dual-clutch transmission

The invention relates to a method for operating a dual-clutch transmission in a motor vehicle according to the preamble of claim 1.

State of the art

In DE 10 2005 053 852 Al is a

Motor Schleppmomentenregelung described for motor vehicles with a dual clutch transmission. Such dual clutch transmissions comprise two parallel transmission lines, in each of which a clutch member which is adjustable between a closed and an open state is arranged, with a continuous force or torque transmission in the drive train being provided via the relevant transmission line of the double clutch when the clutch is closed. At the same time, the clutch is opened in the second gear train, wherein a desired gear can be selected in this gear train, so that a gear change in the shortest possible time by closing the one clutch and opening the other clutch can be performed.

In the engine drag torque control of DE 10 2005 053 852 A1, the setpoint speed of a clutch and the setpoint speed of the internal combustion engine are determined as a function of the desired wheel slip. As a function of a control deviation relating to the setpoint speed of the clutch, the clutch in the dual-clutch transmission is opened or closed. Background is a desired one Compensation of the engine drag torque, so the engine braking effect that can lead to a brake slip on the drive wheels, for example, in the case of a gas take-off or a downshift. By means of the engine drag torque control, the engine torque and thus also the drive wheel speed are increased, which is accompanied by lower brake slip and leads to improved vehicle stability and steerability.

Disclosure of the invention

Based on this prior art, the invention is based on the object to achieve an additional braking effect via a dual-clutch transmission.

This object is achieved with the features of claim 1. The dependent claims indicate expedient developments.

In the inventive method for operating a

Doppelkupplungsgetriebes in a motor vehicle, at least one coupling member in one of the two transmission lines of the dual clutch transmission for generating a braking effect is placed in a sliding position in which the movable coupling parts of this coupling member are in a force or torque transmitting position, but can exert relative movement to each other. The grinding position of the coupling parts is an additional coupling state in which the coupling can be displaced and which is added to the engaged or closed and disengaged or opened coupling state. Design changes are basically not necessary for the realization of the sliding coupling state, since only the coupling parts have to be brought into an approximate state, which lies between the opened and closed clutch, for which existing clutch plates can be used. The relative movement between the coupling parts prevents blockage of the drive train, in particular in the event that according to an advantageous embodiment, the clutch is closed in the second gear train. At the same time, torques are transferred via the sliding position of the coupling parts which have the function of a braking torque effective in the drive train, so that a braking torque can be generated independently of a wheel brake system used in the motor vehicle which acts on the vehicle wheels and brakes them. The dual-clutch transmission as a brake system is an independent brake, which operates independently of other brake systems in the vehicle, so that in order to realize the braking effect on the dual clutch transmission basically no coordination with another brake system is required, which is assigned to a separate from the drive train vehicle domain such as the chassis is.

Another advantage is the ability to brake any actuator, which is located in the drive train or is operatively connected to the drive train. In the case that the dual-clutch transmission is used in a hybrid vehicle having as a drive source, a combination of internal combustion engine and electric motor, which are designed for example as a parallel hybrid, also acting as a drive source electric motor can be braked.

In principle, a second brake, which functions independently of the wheel brake, can be established via the dual-clutch transmission, as a result of which a redundant brake system is achieved overall in the vehicle. For example, the dual-clutch transmission is used as a secondary brake system, which is used in addition to or redundant to the primary brake system. In this case, the primary brake system can be designed as a so-called fail-silent system, which is equipped without a fallback function and in case of damage inoperative; the braking effect is in this situation of the as - A -

Secondary brake system serving dual-clutch transmission generates in which at least one coupling member is placed in the sliding position.

Prerequisite for braking torque generation in

Dual clutch transmission is the sliding position of a coupling member in a first gear train and either also a sliding position or a closed position of the coupling member in the second gear train. In any case, the coupling member in the second gear train must not be in the open position, since in this case no braking effect could be achieved.

In principle, the coupling members in both gear trains of the dual-clutch transmission can be adjusted independently of each other in the sliding position. This makes it possible to close the coupling member in the first gear train and to let it grind in the second gear train or to let the coupling member grind in the first gear train and reverse in the second gear train in reverse execution. Furthermore, both coupling members can be displaced simultaneously into the grinding state for generating a braking torque.

In the braking state are always different

Gear combinations inserted in the first and in the second gear train and active due to the closed or the sliding clutch. It may be appropriate to allow only certain gear combinations during brake torque generation to avoid excessive speed differences in the gear trains and possible damage in the dual-clutch transmission. Preference is always given to immediately successive gear combinations, so for example, the gear combination second / third gear or third / fourth gear. Extreme combinations, such as a gear combination with the highest gear in one gear train and the lowest gear in the other gear train or a Combination with the reverse gear are expediently avoided.

The brake torque generation via the dual-clutch transmission can according to a further advantageous embodiment also as

Parking brake can be used during vehicle standstill. Furthermore, an at least partial compensation of an undesirable torque increase in the drive train can be carried out, which was caused, for example, by a fault reaction of the driver and potentially impairs driving safety, in particular driving stability. The decision about this is preferably automatically in Regelbzw. Control unit in the vehicle pleases, for example in the context of a driver assistance system such as ESP (electronic stability program).

In order to be able to generate the braking torques without damaging coupling parts, it may be expedient to reinforce the corresponding coupling parts of a coupling member, which are preferably designed as cooperating clutch discs. Likewise, gear wheels can be reinforced in the dual clutch transmission.

About a corresponding design of the dual-clutch transmission can be achieved about the drive train of the motor vehicle delays to about 0.3 g, which is basically sufficient for the function as a secondary brake system.

Further advantages and expedient embodiments can be taken from the further claims, the description of the figures and the drawings. Show it:

Fig. 1 is a schematic representation of a

Dual clutch transmission in the drive train of a motor vehicle between an internal combustion engine and a driven wheel, wherein the coupling members are open in the two gear trains of the dual-clutch transmission,

Fig. 2 is a representation corresponding to Fig. 1, but with the first coupling member in the closed and the second coupling member in a grinding state.

In the figures, the same components are provided with the same reference numerals.

Figures 1 and 2 each represent a drive train in a motor vehicle with a drive motor 2, a dual-clutch transmission 3, a differential gear 4 and driven vehicle wheels 5. The drive movement of the drive motor 2 is on the motor shaft on the

Dual clutch transmission 3 transmitted, which is equipped with two parallel gear trains 6 and 7. The drive movement of the motor shaft is fed via a suitable transfer case both gear strands 6 and 7, in each of which a coupling member 8 and 9 is arranged.

In addition, in each gear train 6 and 7 are each a symbolically registered gear box 10 and 11 with a plurality of individual gear stages, which differ from each other, for example, such that in the first gear box 10 odd gears and in the second gear box 11 straight

Gear ratios and beyond that in one of the two gearboxes the reverse gear is included. On the output side, each gear train 6 or 7 is connected to the differential gear 4. With the clutch 8 or 9, the relevant gear train 6 or 7 is active and transmits the rotational movement of the motor shaft with a gear ratio corresponding to the selected gear ratio to the driven vehicle wheels. In addition, in each gear box 10 and 11, a neutral position can be inserted.

Each coupling member 8 and 9 comprises two clutch plates 8a, 8b and 9a, 9b executed coupling parts, the relative each other by means of a clutch actuator are adjustable. In the normal driving mode, the coupling members 8 and 9 between a closed, engaged position in which a force or torque transmission is possible to adjust and an open, disengaged position in which the force or

Moments flow is interrupted. In the normal driving mode, one of the coupling members 8, 9 is always open and the other is closed, and a gear stage is already preselected in the gear train of the opened coupling member and the relevant gear wheel is synchronized with the output shaft.

When changing gear, the closed clutch in the one gear train are opened practically at the same time and closed the open clutch in the other gear train, so that the other gear train is activated.

In Fig. 1, the two coupling members 8, 9 are shown in the open position by way of example. In order to use the dual-clutch transmission 3 also for braking torque generation, the coupling members 8 and 9 are transferred to an additional coupling state in which the clutch plates 8a, 8b and 9a, 9b are placed in a grinding state, in which the respective clutch discs still a

However, due to the sliding position in frictional contact with each other, so that in spite of the relative movement, a moment between the clutch plates involved is transmitted. If, for example, as shown in FIG. 2, for example, the first coupling member 8 is closed and at the same time the second coupling member 9 is transferred into the grinding operating mode, a controllable braking effect is produced in the drive train. The height of the

Braking torque is determined by the amount of force with which the two coupling parts of the sliding coupling member are pressed together.

Basically, each of the two coupling members 8 and 9 closed and the other coupling member are placed in the grinding state to a braking torque in To generate powertrain. In addition, it is also possible for the generation of braking torque to adjust both coupling members 8 and 9 in the sliding position.

The drive motor is in particular an internal combustion engine. Basically, that is

Dual-clutch transmission as a brake system can also be used in drive trains in which an electric motor is used as the drive motor. In addition, a use in hybrid vehicles with a combination of internal combustion engine and electric motor into consideration, which are arranged in particular as a parallel hybrid.

Claims

claims

1. A method for operating a dual-clutch transmission in a motor vehicle, wherein the dual-clutch transmission (3) comprises two parallel transmission lines (6, 7) each with a between a closed and an open state adjustable coupling member (8, 9), the transmission lines (6, 7 ) With closed coupling member (8, 9) a continuous Kraftbzw. Form torque transmission path in the drive train (1) of the motor vehicle and the two coupling members (8, 9) can assume different coupling states, characterized in that for generating a braking torque, the coupling member (8, 9) of a gear train (6, 7) placed in a sliding position is in which the coupling parts (8a, 8b, 9a, 9b) of this coupling member (8, 9) are in a force or torque transmitting position, however, relative to each other exert a relative movement.

2. The method according to claim 1, characterized in that in principle each of the two coupling members (8, 9) can be converted into a grinding position.

3. The method according to claim 1 or 2, characterized in that the coupling member (8, 9) of the one gear train (6, 7) is closed, as long as the coupling member (9, 8) of the other gear train (7, 6) in a grinding Standing position.

4. The method according to any one of claims 1 to 3, characterized in that the coupling member (9, 8) of the other gear train (7, 6) is also placed in a grinding position, as long as the coupling member (8, 9) of the a gear train (6, 7) is in a sliding position.

5. The method according to any one of claims 1 to 4, characterized in that only certain gear combinations between the gear trains (6, 7) are allowed, as long as the coupling member (8, 9) of a gear train (6, 7) is in a sliding position.

6. The method according to claim 5, characterized in that gear combinations with the highest gear in one gear train (6, 7) and the lowest gear in the other gear train (7, 6) are excluded.

7. The method according to any one of claims 1 to 6, characterized in that the generation of a braking torque on the sliding coupling of a gear train (6, 7) of the dual-clutch transmission (3) serves as a secondary brake system, which is used in addition to the primary brake system.

8. The method according to any one of claims 1 to 7, characterized in that the generation of a braking torque on the sliding clutch of a gear train (6, 7) of the dual-clutch transmission (3) is used as a parking brake during vehicle standstill.

9. The method according to any one of claims 1 to 8, characterized in that the braking torque for at least partial compensation of a torque increase in the drive train (1) is used.

10. The method according to any one of claims 1 to 9, characterized in that the amount of the braking torque is determined by the force with which the two coupling parts (8a, 8b, 9a, 9b) of a coupling member (8, 9) are pressed together.

11. regulating or control device for carrying out the method according to one of claims 1 to 10.

12. Motor vehicle with a dual-clutch transmission and a control or control device according to claim 11.

13. Motor vehicle according to claim 12, characterized by an embodiment as a hybrid vehicle with a combination of internal combustion engine and electric motor, in particular as a parallel hybrid vehicle.