Hydraulic braking system, including a control system, and method for controlling said braking system

Patent metadata

Field	Value
Publication number	US-12344206-B2
Application number	US-202217720407-A
Country	US
Kind code	B2
Filing date	Apr 14, 2022
Priority date	Apr 22, 2021
Publication date	Jul 1, 2025
Grant date	Jul 1, 2025

Abstract

The disclosure relates to a method for operating a hydraulic braking system in a motor vehicle having a regenerative braking function. The method comprises steps that, with respect to at least two wheel brakes, a hydraulic free travel release is carried out such that, with respect to one of the at least two wheel brakes, a hydraulic passage to an accumulator is released in order to store therein at least a volume fraction of the hydraulic fluid in the event of a displacement of a hydraulic fluid. The other of the at least two wheel brakes is hydraulically isolated. The disclosure also relates to a hydraulic braking system for a motor vehicle having a regenerative braking function and a method for controlling said braking system.

First claim

The invention claimed is:

1. A method for operating a hydraulic braking system in a motor vehicle having a regenerative braking function first and second wheel brakes, wherein with respect to the at least second wheel brake carrying out a hydraulic free travel release to open an opening device of the at least second wheel brake such that, with respect to the at least second wheel brake, a hydraulic passage to an accumulator is released, thereby storing therein at least a volume fraction of a hydraulic fluid in the event of a displacement of the hydraulic fluid, and closing an isolation valve such that the at least one other wheel brake is hydraulically isolated when a generative braking force of an electrical machine is present or about to occur.

2. The method according to claim 1 , wherein a further hydraulic passage to the accumulator remains closed with respect to the at least one other wheel brake.

3. The method according to claim 1 , wherein, with respect to the at least one other wheel brake, a further hydraulic passage to the accumulator or to a further accumulator is released.

4. A hydraulic braking system for a motor vehicle having a regenerative braking function, comprising:
a brake cylinder and at least two wheel brakes, wherein the brake cylinder is hydraulically connected to the at least two wheel brakes via a hydraulic connection and designed to displace a hydraulic fluid in a direction of the at least two wheel brakes, and wherein the at least two wheel brakes are designed to exert a hydraulic braking force by of the hydraulic fluid;
wherein the at least two wheel brakes comprise a first wheel brake and a second wheel brake, each of the first and second wheel brakes having:
a drain line for draining at least a volume fraction of the hydraulic fluid from the hydraulic connection between the brake cylinder and the associated wheel brake;
an opening device for opening the hydraulic connection between the brake cylinder and the associated wheel brake in order to drain the at least one volume fraction of the hydraulic fluid into the drain line;
wherein at least the first wheel brake is assigned an isolation valve for closing the hydraulic connection between the brake cylinder and the first wheel brake in order to hydraulically isolate the first wheel brake;
the hydraulic braking system further comprising:
at least one accumulator which is hydraulically connected to the drain line and designed to store at least a volume fraction of the hydraulic fluid under an accumulator pressure; and
a control unit which is designed to cause the opening device of the first wheel brake and the opening device of the second wheel brake to open and the isolation valve to close when a generative braking force of an electrical machine is present or about to occur.

5. The braking system according to claim 4 , wherein the control unit is designed to cause the opening device of the second wheel brake to open and the isolation valve to close when a generative braking force of the electrical machine is present or about to occur, and-when a gradient of an actuation path of an actuation element operatively connected to the brake cylinder or a momentary value of a parameter corresponding thereto is smaller than a default value.

6. The braking system according to claim 4 , wherein the control unit is designed to cause the opening device of the first wheel brake and the opening device of the second wheel brake to open and to cause the isolation valve to close when a generative braking force of the electrical machine is present or about to occur, and-when a gradient of an actuation travel of an actuation element operatively connected to the brake cylinder or a momentary value of a parameter corresponding thereto is smaller than a default value.

7. The braking system according to claim 4 , wherein the accumulator is a piston accumulator.

8. The braking system according to claim 4 , further comprising
a pump for returning at least a volume fraction of the hydraulic fluid from the drain line and/or the accumulator in the direction of the brake cylinder and/or for building up hydraulic pressure in the at least two wheel brakes,
wherein the control unit is signal-connected to the pump and designed to control the pump in order to return at least a volume fraction of the hydraulic fluid from the drain line and/or the accumulator in a direction of the brake cylinder or to build up hydraulic pressure in the at least two wheel brakes.

9. A hydraulic braking system for a motor vehicle having a regenerative braking function, comprising:
a brake cylinder and at least two wheel brakes, wherein the brake cylinder is hydraulically connected to the at least two wheel brakes via a hydraulic connection and designed to displace a hydraulic fluid in a direction of the at least two wheel brakes, and wherein the at least two wheel brakes are designed to exert a hydraulic braking force by of the hydraulic fluid;
wherein the at least two wheel brakes comprise a first wheel brake and a second wheel brake, each of the first and second wheel brakes having:
a drain line for draining at least a volume fraction of the hydraulic fluid from the hydraulic connection between the brake cylinder and the associated wheel brake;
an opening device for opening the hydraulic connection between the brake cylinder and the associated wheel brake in order to drain the at least one volume fraction of the hydraulic fluid into the drain line;
wherein at least the first wheel brake is assigned an isolation valve for closing the hydraulic connection between the brake cylinder and the first wheel brake in order to hydraulically isolate the first wheel brake;
the hydraulic braking system further comprising:
at least one accumulator which is hydraulically connected to the drain line and designed to store at least a volume fraction of the hydraulic fluid under an accumulator pressure, and
wherein the control unit is designed to cause the opening device of the second wheel brake to open and the isolation valve to close when a generative braking force of the electrical machine is present or about to occur, wherein the opening device of the first wheel brake remains in a closed position.

10. The braking system according to claim 9 , wherein the control unit is designed to cause the opening device of the second wheel brake to open and the isolation valve to close when a generative braking force of the electrical machine is present or about to occur, and when a gradient of an actuation path of an actuation element operatively connected to the brake cylinder or a momentary value of a parameter corresponding thereto is smaller than a default value, wherein the opening device of the first wheel brake remains in a closed position.

11. The braking system according to claim 9 , wherein at least the first wheel brake is further assigned a pressure relief device which is fluidically connected in parallel to the opening device of the first wheel brake and has an inlet side and an outlet side, wherein the pressure relief device is closed in a draining direction and opens in the opposite direction of the draining direction when a maximum pressure difference between the input side and the output side is reached.

12. The braking system according to claim 11 , wherein the pressure relief device is set to a difference value for a maximum pressure difference between the input side and the output side of the opening device, which is smaller than a maximum pressure difference between an accumulator pressure of the accumulator and a fluid pressure in the first wheel brake.

13. The braking system according to claim 11 , wherein the opening device of th

Assignees

• Zf Active Safety Gmbh

Inventors

• Hoffmann Elmar
• Lahnstein Jonas
• Koeth Boris
• Schmidt Frank
• Thelen Harald

Classifications

• B60L7/26

  Controlling the braking effect · CPC title

• B60T13/148 Primary

  Arrangements for pressure supply · CPC title

• B60T2270/604

  Merging friction therewith; Adjusting their repartition · CPC title

• B60T17/22

  Devices for monitoring or checking brake systems; Signal devices · CPC title

• B60T7/042

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