Electrohydraulic Motor Vehicle Brake System and Method for Operating the Same

• US 20150353067A1
• Filed: 11/28/2013
• Published: 12/10/2015
• Est. Priority Date: 12/21/2012
• Status: Active Grant

• Current Assignee: Lucas Automotive GmbH (Zeppelin - Stiftung der Stadt Friedrichshafen)
• Original Assignee: Lucas Automotive GmbH (Zeppelin - Stiftung der Stadt Friedrichshafen)
• Inventors: Knechtges, Josef
• Granted Patent: US 10,029,659 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: B60T 13/662 characterised by specified functions of the control system components
• CPC Class Codes: B60T 13/686 in hydraulic systems or parts thereof
• CPC Class Codes: B60T 13/745 acting on a hydraulic system, e.g. a master cylinder
• CPC Class Codes: B60T 7/042 by electrical means, e.g. using travel or force sensors
• CPC Class Codes: B60T 8/4077 Systems in which the booster is used as an auxiliary pressure source

Abstract

The invention relates to a technique for operating an electrohydraulic motor vehicle brake system comprising a master cylinder (or any other cylinder-piston arrangement) that can be supplied with a hydraulic fluid from a reservoir, an electromechanical actuator for actuating a piston accommodated in the master cylinder, a wheel brake that can be coupled to the master cylinder, and a stop valve provided between the master cylinder and the wheel brake. According to an aspect of this technique, the method comprises the steps of: controlling the electromechanical actuator to build up hydraulic pressure on the wheel brake; controlling the stop valve to hold the hydraulic pressure already built up on the wheel brake; controlling the electromechanical actuator to take in hydraulic fluid from the reservoir while monitoring a time response of a pressure drop in the master cylinder associated with the take-in; and interrupting the take-in depending on a result of the monitoring.

Claims

1. Method for operating an electrohydraulic motor vehicle brake system having a cylinder-piston arrangement that can be supplied with hydraulic fluid from a reservoir, an electromechanical actuator for actuating a piston accommodated in the cylinder-piston arrangement, a wheel brake that can be coupled to the cylinder-piston arrangement, and a shut-off valve provided between the cylinder-piston arrangement and the wheel brake, comprising the steps of:

activating the electromechanical actuator for generating a hydraulic pressure at the wheel brake;

activating the shut-off valve for locking the hydraulic pressure already generated at the wheel brake;

activating the electromechanical actuator for an intake of hydraulic fluid from the reservoir while monitoring a temporal behaviour of a pressure drop in the cylinder-piston arrangement that accompanies the intake; and

terminating the intake dependent on a result of the monitoring.

2. Method according to claim 1, wherein the intake is terminated when the result of the monitoring indicates a lack of operability of the shut-off valve or activation of the shut-off valve.

3. Method according to claim 1, wherein the intake is terminated when the pressure drop takes place more slowly than according to a specified time criterion.

4. Method according to claim 3, wherein the specified time criterion states that the pressure drop to a substantially pressureless state must take place within approximately 5 to 50 ms.

5. Method according to claim 1, wherein the intake is terminated before the pressure drop is approximately 10 to 40 bar.

6. Method according to claim 1, wherein in connection with the terminating of the intake, the shut-off valve is activated in order to open it.

7. Method according to claim 1, wherein in connection with the terminating of the intake, the electromechanical actuator is activated to increase the hydraulic pressure.

8. Method according to claim 1, wherein the method is carried out within the context of a test phase in which the vehicle is at a standstill.

9. Computer program product having a programming code for performing the method according to claim 1 when the computer program is run on a processor.

10. Motor vehicle electronic control unit or electronic control unit system comprising the computer program product according to claim 9.

11. Electrohydraulic motor vehicle brake system, comprising:

a cylinder-piston arrangement that can be supplied with hydraulic fluid from a reservoir;

an electromechanical actuator for actuating a piston accommodated in the cylinder-piston arrangement;

a wheel brake that can be coupled to the cylinder-piston arrangement;

a shut-off valve provided between the cylinder-piston arrangement and the wheel brake; and

an electronic control unit or electronic control unit system which is configured to

activate the electromechanical actuator for generating a hydraulic pressure at the wheel brake;

activate the shut-off valve for locking the hydraulic pressure already generated at the wheel brake;

activate the electromechanical actuator for an intake of hydraulic fluid from the reservoir while monitoring a temporal behaviour of a pressure drop in the cylinder-piston arrangement that accompanies the intake; and

terminate the intake dependent on a result of the monitoring.

12. Brake system according to claim 11, further comprising:

a valve system for vehicle dynamics control, wherein the shut-off valve is arranged between the cylinder-piston arrangement and the valve system for vehicle dynamics control or is part of that valve system.

13. Brake system according to claim 11, wherein the shut-off valve, together with further shut-off valves which are assigned to further wheel brakes, can be operated in multiplex operation in order to carry out vehicle dynamics control.

14. Brake system according to claim 12, wherein the vehicle dynamics control comprises at least one of the following control systems:

an anti-lock brake system, a traction control system, and an electronic stability program.

15. Apparatus according to claim 11, wherein the dimensions of the cylinder-piston arrangement are such that it has no volume reserve to compensate for fading.

16. Apparatus according to claim 11, further comprising:

a mechanical actuator which can be coupled or is coupled to a brake pedal, for actuating the piston accommodated in the cylinder-piston arrangement.

17. Apparatus according to claim 11, wherein the cylinder-piston arrangement is a master cylinder of the brake system.