Electrohydraulic vehicle brake system having an electromechanical actuator and method for operating the brake system

Patent metadata

Field	Value
Publication number	US-10449938-B2
Application number	US-201414914966-A
Country	US
Kind code	B2
Filing date	Aug 20, 2014
Priority date	Aug 26, 2013
Publication date	Oct 22, 2019
Grant date	Oct 22, 2019

Abstract

An electrohydraulic vehicle brake system includes an electromechanical actuator for actuating at least one hydraulic piston to build hydraulic pressure at wheel brakes. The brake system provides a set of electrically activatable valve arrangements having a first valve arrangement between a cylinder accommodating the at least one hydraulic piston and each of the wheel brakes, and at least one second valve arrangement between a receptacle device for hydraulic fluid and at least one of the wheel brakes. The second valve arrangement is provided in parallel with the first valve arrangement which is associated with the same wheel brake as the second valve arrangement. A control device or system activates the first valve arrangements and the electromechanical actuator, in order to build up a hydraulic pressure at at least one of the wheel brakes and via the opened first valve arrangement associated with that wheel brake and to reduce a built-up hydraulic pressure via the opened first valve arrangement. The activation of the first valve arrangements can take place in a time multiplex operation.

First claim

The invention claimed is:

1. An electrohydraulic vehicle brake system, comprising:
an electromechanical actuator for actuating at least one hydraulic piston in order to set a hydraulic pressure at one or more of a plurality of wheel brakes;
a receptacle device;
a set of electrically activatable valve arrangements having
a respective first valve arrangement between a cylinder accommodating the at least one hydraulic piston and each of the plurality of wheel brakes, and
at least one second valve arrangement between the receptacle device for hydraulic fluid and at least one of the wheel brakes, wherein the at least one second valve arrangement is provided in parallel with that one of the first valve arrangements which is associated with the same wheel brake as the at least one second valve arrangement; and
a control device or control device system configured to during a dynamic control operation performed by a dynamic control system activate the first valve arrangements and the electromechanical actuator, in order to build up a hydraulic pressure at at least one of the wheel brakes and via the opened first valve arrangement associated with that wheel brake and to reduce a built-up hydraulic pressure via the opened first valve arrangement, wherein the at least one second valve arrangement and that one of the first valve arrangements which is associated with the same wheel brake as the second valve arrangement are arranged serially in a hydraulic path between the cylinder and the receptacle device, and wherein the control device or control device system is configured to open the second valve arrangement and the first valve arrangement associated with the same wheel brake, in order to fluidically couple the cylinder to the receptacle device.

2. The electrohydraulic vehicle brake system according to claim 1 , wherein
the control device or control device system is configured to reduce the hydraulic pressure built up at a wheel brake, selectively by opening the associated first valve arrangement or by opening the associated second valve arrangement.

3. The electrohydraulic vehicle brake system according to claim 2 , wherein
the control device or control device system is configured to reduce the hydraulic pressure at the wheel brake via the opened second valve arrangement if, at at least one other of the wheel brakes, a hydraulic pressure reduction takes place with insufficient speed or a hydraulic pressure build-up takes place, wherein the hydraulic pressure reduction at this other of the wheel brakes takes place via the opened first valve arrangement associated with this other wheel brake and by means of the electromechanical actuator.

4. The electrohydraulic vehicle brake system according to claim 1 , wherein
the control device or control device system is configured to actuate the first valve arrangements in a time multiplex operation, wherein at least one time slot is associated with each of the first valve arrangements and thus with each wheel brake.

5. The electrohydraulic vehicle brake system according to claim 4 , wherein
the control device or control device system is configured to reduce the hydraulic pressure build up at a wheel brake by opening the associated second valve arrangement; and
the control device or control device system is configured to reduce the hydraulic pressure at the wheel brake via the opened second valve arrangement during a time slot associated with another wheel brake.

6. The electrohydraulic vehicle brake system according to claim 1 , wherein
the control device or control device system is configured to actuate the electromechanical actuator when the receptacle device is fluidically coupled to the cylinder, in order to release hydraulic fluid from the cylinder into the receptacle device.

7. The electrohydraulic vehicle brake system according to claim 1 , wherein
the control device or control device system is configured to actuate the electromechanical actuator when the receptacle device is fluidically coupled to the cylinder, in order to suck hydraulic fluid from the receptacle device into the cylinder.

8. The electrohydraulic vehicle brake system according to claim 1 , which
comprises at least one nonreturn valve which is provided in a hydraulic path between the cylinder and the receptacle device and the let-through direction of which is directed towards the cylinder.

9. The electrohydraulic vehicle brake system according to claim 8 , wherein
the control device or control device system is configured to suck hydraulic fluid from the receptacle device via the nonreturn valve into the cylinder by actuating the electromechanical actuator.

10. The electrohydraulic vehicle brake system according to claim 9 , wherein
the nonreturn valve is provided in the hydraulic path between the cylinder and the receptacle device in such a manner that the sucking-in can also take place in at least one of the following situations:
when one of the first valve arrangements, a plurality of the first valve arrangements, or all of the first valve arrangements is closed; and
when the at least one second valve arrangement is closed.

11. The electrohydraulic vehicle brake system according to claim 8 , wherein
the nonreturn valve has at least one of an opening cross-section of more than 10 mm 2 and a rubber sealing seat.

12. The electrohydraulic vehicle brake system according to claim 8 , wherein
the cylinder comprises two chambers which are respectively connected to the receptacle device, wherein a separate nonreturn valve is associated with each chamber.

13. The electrohydraulic vehicle brake system according to claim 1 , wherein
the cylinder accommodating the at least one hydraulic piston is a master cylinder or a cylinder connected in parallel with the master cylinder.

14. The electrohydraulic vehicle brake system according to claim 1 , wherein
the receptacle device is configured as a pressure accumulator.

15. The electrohydraulic vehicle brake system according to claim 1 , wherein
the receptacle device is configured as an unpressurised hydraulic fluid reservoir.

16. The electrohydraulic vehicle brake system according to claim 1 , wherein
the electromechanical actuator comprises an electric motor and a transmission coupled to the electric motor, wherein the transmission is coupled to an actuating member acting on the at least one hydraulic piston.

17. The electrohydraulic vehicle brake system according to claim 1 , wherein
the electromechanical actuator is activatable for hydraulic pressure generation in a “brake-by-wire” mode of the brake system.

18. The electrohydraulic vehicle brake system according to claim 1 , further comprising
an actuator for hydraulic pressure generation in a “push-through” mode of the brake system.

19. The electrohydraulic vehicle brake system according to claim 1 , wherein
the first valve arrangements comprise respectively only one first valve.

20. The electrohydraulic vehicle brake system according to claim 19 , wherein
the first valve is opened in the absence of electrical activation.

21. The electrohydraulic vehicle brake system according to claim 1 , wherein
the at least one second valve arrangements comprises only one valve.

22. The electrohydraulic vehicle brake system according to claim 21 , wherein
the second valve is closed in the absence of electrical activation.

23. The electrohydraulic vehicle brake system according to claim 1 , wherein
a throttling effect of the

Assignees

• Lucas Automotive Gmbh

Inventors

• Knechtges Carsten
• Knechtges Josef
• Passmann Andreas

Classifications

• B60T7/042 Primary

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

• B60T8/4077

  Systems in which the booster is used as an auxiliary pressure source · CPC title

• B60T13/745

  acting on a hydraulic system, e.g. a master cylinder · CPC title

• B60T8/50 Primary

  having means for controlling the rate at which pressure is reapplied to {or released from} the brake · CPC title

• B60T13/662

  characterised by specified functions of the control system components · CPC title