Method for operating a brake system and a brake system

Patent metadata

Field	Value
Publication number	US-9365199-B2
Application number	US-201314380970-A
Country	US
Kind code	B2
Filing date	Feb 14, 2013
Priority date	Feb 28, 2012
Publication date	Jun 14, 2016
Grant date	Jun 14, 2016

Abstract

A method and system for operating a motor vehicle brake system, actuated in a “Brake-by-Wire” operating mode both by the vehicle driver and also independent of the vehicle driver, preferably operated in the “Brake-by-Wire” operating mode, and which can be operated in at least one fall-back operating mode, in which only operation by the vehicle driver is possible. The brake system has an electrohydraulic pressure and volume setting device, which electronically emits a brake system pressure under control, and a pressure modulation unit having, for each wheel brake, inlet and outlet valves for setting wheel-specific brake pressures. For setting wheel-specific brake pressures, the inlet and outlet valves are actuated analogously by being energized by different electrical currents, in order to assign a pressurizing agent volume flow provided by the pressure and volume setting device to the wheel brakes that have a pressure change requirement.

First claim

The invention claimed is:

1. A method for operating a brake system for motor vehicles, which can be controlled in a “brake-by-wire” operating mode both by the vehicle driver and also independently of the vehicle driver, is preferably operated in the “brake-by-wire” operating mode, and can be operated in at least one fall-back operating mode, with
hydraulic wheel brakes
a brake master cylinder having at least one pressure space, with the pressure in which at least the wheel brakes of a front axle of the motor vehicle can be supplied in the fall-back operating mode,
a pressure medium reservoir,
a brake pedal for actuating the brake master cylinder,
brake circuits, which have brake master cylinder and wheel brake pressure spaces, hydraulic connections and electrohydraulic control elements,
an electrically actuable isolating valve for each brake circuit for dividing the brake circuit into a brake circuit section which can be subjected to pressure by the vehicle driver and a brake circuit section which can be subjected to pressure “by wire”,
an electrically actuable inlet valve and an electrically actuable outlet valve for each wheel brake for setting wheel-specific brake pressures, an outlet side of each outlet valve being connected without an intervening valve to an inlet side of a respective one of the inlet valves,
an electrically controllable pressure and volume setting device,
an electrically actuable connection valve, which is closed when deenergized, for each brake circuit for hydraulic connection of the electrically controllable pressure and volume setting device to the brake circuit section which can be subjected to pressure “by wire”,
a simulation device, which can be connected hydraulically to at least one pressure space of the brake master cylinder and can be activated by means of an electrically or mechanically actuable simulator enable valve, having a preset characteristic, and which gives the vehicle driver a pleasant brake pedal feel in the “brake-by-wire” operating mode, and
an electronic open- and closed-loop control unit, for controlling the pressure and volume setting device, the isolating valves, the connection valves, the simulator enable valve and the inlet and outlet valves,
wherein, to set wheel-specific brake pressures, the inlet and outlet valves are controlled in an analog manner by being supplied with different electric currents in order to allocate a pressure medium volume flow made available by the pressure and volume setting device to the wheel brakes having a requirement for a change in pressure.

2. The method as claimed in claim 1 , wherein the electrically controllable pressure and volume setting device is used to displace pressure medium volumes which are proportioned according to the desired changes in wheel brake pressure and, by the different control currents of the brake pressure modulation valves, are passed to the selected wheel brakes as an inlet flow or out of the wheel brakes selected for a pressure reduction as a volume discharge flow.

3. The method as claimed in claim 2 , wherein, when a simultaneous pressure buildup is required in several wheel brakes, the control currents of the brake pressure buildup or inlet valves of the remaining wheel brakes are increased, and a pressure medium volume is displaced into the selected wheel brakes by means of the electrically controllable pressure and volume setting device, in order to increase the pressure in the selected wheel brakes.

4. The method as claimed in claim 3 , wherein the control currents of the inlet valves of the selected wheel brakes are reduced cyclically in relation to one another during pressure buildup, with the result that the duration of current reduction defines the share of the selected wheel brake in the pressure buildup volume.

5. The method as claimed in claim 2 , wherein, when a simultaneous pressure reduction is required in several wheel brakes, the control currents of the brake pressure reduction or outlet valves of selected wheel brakes are reduced, and an appropriately proportioned pressure medium volume is removed from of the selected wheel brakes by means of the electrically controllable pressure and volume setting device, in order to reduce the pressure in the selected wheel brakes.

6. The method as claimed in claim 5 , wherein the control currents of the outlet valves of the selected wheel brakes are reduced cyclically in relation to one another during pressure reduction, with the result that the duration of current reduction defines the share of the selected wheel brake in the pressure reduction volume.

7. The method as claimed in claim 6 , wherein at least some of the reduction volume flow on the part of the pressure and volume setting device is provided by opening a solenoid valve.

8. The method as claimed in claim 5 , wherein at least some of the reduction volume flow on the part of the pressure and volume setting device is provided by opening a solenoid valve.

9. The method as claimed in claim 1 , wherein, to increase the pressure in a selected wheel brake, the control currents for the pressure buildup or inlet valves of the other wheel brakes are increased relative to the selected wheel brake, and a pressure medium volume is displaced into the selected wheel brake by means of the controllable pressure and volume setting device.

10. The method as claimed in claim 1 , wherein, to reduce the pressure in a selected wheel brake, the control currents for the pressure reduction or outlet valves of the other wheel brakes are increased relative to the selected wheel brake, and a pressure medium volume is removed from the selected wheel brake by means of the electrically controllable pressure and volume setting device.

11. The method as claimed in claim 10 , wherein at least some of the reduction volume flow on the part of the pressure and volume setting device is provided by opening a solenoid valve.

12. The method according to claim 1 , wherein all the wheel brakes can be supplied in the fall-back operating mode.

13. A brake system for carrying out the method as claimed in claim 1 , wherein the wheel brake pressure modulation valves or inlet and outlet valves for each wheel are designed as 2/2-way valves which can be subjected to analog control and are open when deenergized.

14. The brake system as claimed in claim 13 , wherein ports of the outlet valves which face away from the wheel brakes are connected in circuits with ports of the inlet valves which face away from the wheel brakes.

15. The brake system as claimed in claim 14 , wherein the installation orientation of the outlet valves is chosen in such a way that they are acted upon in the opening direction by the wheel brake pressures.

16. The brake system as claimed in claim 13 , wherein the installation orientation of the outlet valves is chosen in such a way that they are acted upon in the opening direction by the wheel brake pressures.

17. The brake system as claimed in claim 13 , wherein the installation orientation of the inlet valves is chosen in such a way that they are acted upon in the closing direction by the wheel brake pressures.

18. The brake system as claimed in claim 13 , wherein an electromagnetically actuable 2/2-way valve which is inserted between the system pressure line and the pressure medium feed line and is closed when deenergized as part of the pressure and volume setting device is provided.

19. The brake system as claimed in claim 18 , wherein, during pressure and volume reduction processes, a pressure medium volume flow is passed from the system

Assignees

• Continental Teves Ag & Co Ohg

Inventors

• Drumm Stefan A

Classifications

• B60T11/103

  in combination with other control devices (conjoint control of brake system and at least another sub-unit B60W10/188) · CPC title

• B60T13/686

  in hydraulic systems or parts thereof · CPC title

• B60T7/042

  by electrical means, e.g. using travel or force sensors · CPC title

• B60T11/28

  Valves specially adapted therefor (recuperation valves B60T11/232) · CPC title

• B60T8/367

  Seat valves, e.g. poppet valves · CPC title