Braking method for a vehicle

• US 20060113158A1
• Filed: 05/15/2004
• Published: 06/01/2006
• Est. Priority Date: 06/14/2003
• Status: Active Grant

• Current Assignee: ZF Friedrichshafen AG (Zeppelin - Stiftung der Stadt Friedrichshafen)
• Original Assignee: ZF Friedrichshafen AG (Zeppelin - Stiftung der Stadt Friedrichshafen)
• Inventors: Popp, Christian, Schwemer, Christian, Schiele, Peter, Steinhauser, Klaus, Allgaier, Bernd, Gierer, Georg
• Granted Patent: US 7,416,071 B2
• Time in Patent Office: Days
• US Class Current: 192/220
• CPC Class Codes: B60T 2270/404 Brake-by-wire or X-by-wire failsafe
• CPC Class Codes: B60T 8/885 using electrical circuitry
• CPC Class Codes: B60W 10/10 including control of change-speed gearings
• CPC Class Codes: B60W 10/18 including control of braking systems
• CPC Class Codes: B60W 2540/12 Brake pedal position
• CPC Class Codes: B60W 30/18109 Braking
• CPC Class Codes: B60W 30/1819 Propulsion control with control means using analogue circuits, relays or mechanical links
• CPC Class Codes: F16H 2059/725 Sensing or calculating temperature of friction devices, e.g. clutches to prevent overheating of friction linings
• CPC Class Codes: F16H 2061/122 Avoiding failures by using redundant parts
• CPC Class Codes: F16H 2061/213 for emergency braking, e.g. for increasing brake power in emergency situations
• CPC Class Codes: F16H 59/54 dependent on signals from the brakes, e.g. parking brakes
• CPC Class Codes: F16H 61/0059 Braking of gear output shaft using simultaneous engagement of friction devices applied for different gear ratios

Abstract

A braking method for a vehicle is proposed as a safety measure and replacement function if the brake system fails, in particular the X-by-wire brake system of a motor vehicle, in which the vehicle is braked with the help of the transmission by a defined engagement of frictional shift elements until the vehicle comes to rest, such that the combination of frictional shift elements actuated when the vehicle'"'"'s working brake system fails does not correspond to the shift logic of a gear during normal driving operation of the vehicle.

Claims

1-11. -11. (canceled)

12. A braking method for a vehicle, for use as a safety measure and replacement function in the event that a working brake system of the vehicle fails, in particular a X-by-wire brake system,

in which the vehicle is braked with help of a transmission by means of a defined engagement of frictional shift elements until the vehicle is at rest, a combination of frictional shift elements engaged when the working brake system of the vehicle fails, does not correspond to a shift logic of a gear during normal driving operation of the vehicle and,

starting from a gear engaged at a time when the vehicle'"'"'s working brake system fails, at least one additional frictional shift element of the transmission is engaged in such manner that drive wheels of the vehicle undergo one of a maximum or a specified braking, but such that the vehicle'"'"'s drive wheels are not locked while an actual speed of the vehicle is greater than a defined value,

a shifting pressure or a torque is set at a first frictional shift element engaged additionally compared with the normal shift logic, a shifting pressure or torque to be set, being determined as a function of one or more of a brake pedal actuation force, an ACC-radar sensor (distance control unit) and an actual speed of the vehicle.

13. The braking method for a vehicle according to claim 12, wherein as soon as the failure of the vehicle'"'"'s working brake system has been recognized, the vehicle is automatically braked by means of the transmission.

14. The braking method for a vehicle according to claim 12 wherein, if the vehicle'"'"'s working brake system fails, the vehicle is automatically braked by the transmission when a vehicle brake pedal is actuated.

15. The braking method for a vehicle according to claim 12, wherein as a function of the vehicle'"'"'s actual speed, a respective shift element combination is engaged, whereby optimum or maximum vehicle braking is achieved with least possible stress on the transmission or frictional shift elements of the transmission.

16. The braking method for a vehicle according to claim 12, wherein a shift takes place to a second additional frictional shift element of the transmission compared with the normal shift logic, when a limiting thermal load of a first frictional shift element engaged additionally compared with normal shift logic is reached.

17. The braking method for a vehicle according to claim 12, wherein a shift to a higher or lower gear with a different combination of frictional shift elements takes place, when a limiting thermal load of a first frictional shift element engaged additionally compared with normal shift logic is reached.

18. The braking method for a vehicle according to claim 12, wherein the vehicle is braked additionally or alternatively by actuating one of two frictional shift elements in the transmission or a separate frictional shift element acting on a drive output of the transmission.

19. The braking method for a vehicle according to claim 12, wherein when the vehicle is nearly or actually at rest, one or more of a parking lock of the transmission and a parking brake of the vehicle is automatically engaged.

20. A braking method for a vehicle having one of a change-under-load transmission, a continuously variable transmission, an automated shift transmission or a dual clutch transmission,the method for use as a safety measure and replacement function in the event that a working brake system of the vehicle fails, in particular a X-by-wire brake system,

in which the vehicle is braked with help of a transmission by means of a defined engagement of frictional shift elements until the vehicle is at rest, a combination of frictional shift elements engaged when the working brake system of the vehicle fails, does not correspond to a shift logic of a gear during normal driving operation of the vehicle and,

starting from a gear engaged at a time when the vehicle'"'"'s working brake system fails, at least one additional frictional shift element of the transmission is engaged in such manner that drive wheels of the vehicle undergo one of a maximum or a specified braking, but such that the vehicle'"'"'s drive wheels are not locked while an actual speed of the vehicle is greater than a defined value,

a shifting pressure or a torque is set at a first frictional shift element engaged additionally compared with the normal shift logic, a shifting pressure or torque to be set, being determined as a function of one or more of a brake pedal actuation force, an ACC-radar sensor (distance control unit) and an actual speed of the vehicle.

21. A braking method for a vehicle, for use as a safety measure and replacement function in an event that a X-by-wire brake system of the vehicle fails, the vehicle is braked with help of a transmission by means of a defined engagement of frictional shift elements until the vehicle is at rest, a combination of frictional shift elements engaged when the working brake system of the vehicle fails, does not correspond to a shift logic of a gear during normal driving operation of the vehicle, the method comprising the steps of;

engaging at least one additional frictional shift element of the transmission, starting from a gear engaged at a time when the vehicle'"'"'s working brake system fails, in such manner that drive wheels of the vehicle undergo one of a maximum or a specified braking, but such that the vehicle'"'"'s drive wheels are not locked while an actual speed of the vehicle is greater than a defined value,

setting one of a shifting pressure or a torque at a first frictional shift element engaged additionally compared with the normal shift logic, and

determining one of a shifting pressure or torque to be set, as a function of one or more of a brake pedal actuation force, an ACC-radar sensor (distance control unit) and an actual speed of the vehicle.