Motor vehicle with auxiliary brake and method to control speed change during shifting such a vehicle

1. A motor vehicle comprising:

an internal combustion engine, a transmission, driving and non-driving wheels;

a first and a second brake device, said first brake device acting directly on at least some of the wheels of the vehicle and said second brake device acting on the driving wheels of the vehicle via the transmission; and

said second brake device is arranged before a clutch of the transmission and said first brake device is activated when said second brake device is in an activated state and when a shifting operation is started and whereby controlled braking effect is imparted to the motor vehicle when said first braking device is coupled to wheels of the vehicle while the second brake device is decoupled from the wheels of the vehicle during the shifting operation.

2. The motor vehicle as recited in claim 1 , wherein said first brake device is deactivated when the shifting operation is finished.

3. The motor vehicle as recited in claim 1 , wherein said second brake device is deactivated when the shifting operation is started.

4. The motor vehicle as recited in claim 3 , wherein said first brake device is activated at the same time as the second brake device is deactivated so that the total braking effect is constant.

5. The motor vehicle as recited in claim 3 , wherein said first brake device is deactivated and said second brake device is activated when the shifting operation is finished.

6. The motor vehicle as recited in claim 1 , wherein said first brake device further comprises friction brakes mounted at the wheels of the vehicle.

7. The motor vehicle as recited in claim 1 , wherein said first brake device comprises a secondary retarder mounted after the transmission of the vehicle.

8. The motor vehicle as recited in claim 7 , wherein the braking effect of said first brake device is distributable between (1) the wheel brakes and (2) the secondary retarder of the vehicle.

9. The motor vehicle as recited in claim 1 , wherein said second brake device comprises at least one of (1) a primary retarder, (2) a compression brake and (3) an exhaust-gas brake.

10. The motor vehicle as recited in claim 1 , wherein said transmission further comprises an automatically shifted multi-stage gearbox.

11. The motor vehicle as recited in claim 1 , wherein said motor vehicle consists of a vehicle combination comprising a traction vehicle and a towed vehicle.

12. The motor vehicle as recited in claim 11 , wherein the braking effect of said first brake device is distributed between (1) the wheel brakes of the vehicle, (2) wheel brakes of the towed vehicle, and (3) the secondary retarder of the vehicle.

13. A method for obtaining a controlled speed change during a shifting operation for a vehicle including an internal combustion engine, a transmission, and first and second brake devices, wherein the first brake device acts directly on at least some of the wheels of the vehicle and the second brake device acts on driving wheels of the vehicle via the transmission and is arranged before a clutch device of the transmission so that controlled braking effect is imparted to the motor vehicle when said first braking device is coupled to wheels of the vehicle while the second brake device is decoupled from the wheels of the vehicle during the shifting operation, said method further comprising detecting that a shifting operation has been started and activating the first brake device with a braking effect which corresponds to the braking effect of the second brake device.

14. The method as recited in claim 13 , further comprising deactivating the first brake device when the shifting operation has been finished.

15. The method as recited in claim 13 , further comprising deactivating the second brake device when the shifting operation is started.

16. The method as recited in claim 15 , further comprising activating the first brake device and deactivating the second brake device takes place at the same time so that the total braking effect is constant.

17. The method as recited in claim 16 , further comprising deactivating the first brake device and activating the second brake device when the shifting operation is finished.

18. The method as recited in claim 13 , further comprising said first brake device including at least one of (1) wheel brakes and (2) a secondary retarder.

19. The method as recited in claim 18 , further comprising distributing the braking effect of the first brake device between at least one of (1) the wheel brakes and (2) the secondary retarder of the vehicle.

20. The method as recited in claim 13 , wherein said second brake device comprises at lest one of (1) a primary retarder, (2) a compression brake and (3) an exhaust-gas brake.

21. The method as recited in claim 13 , wherein said transmission comprises an automatically shifted multi-stage gearbox.

22. The method as recited in claim 13 , wherein said method is performed via a computer program comprising program code for performing the method steps and which is executed by a computer.

23. The method as recited in claim 13 , wherein said method is performed via a computer program product comprising program code stored on a computer-readable medium for implementing the method steps when said program is executed by a computer.