Hydraulic brake system for a motor vehicle and method for operating and testing same

Patent metadata

Field	Value
Publication number	US-11014545-B2
Application number	US-201816479310-A
Country	US
Kind code	B2
Filing date	Jan 19, 2018
Priority date	Jan 19, 2017
Publication date	May 25, 2021
Grant date	May 25, 2021

Abstract

A hydraulic brake system for a motor vehicle with redundant braking pressure regulation is presented. The brake system comprises a first functional unit having at least one first electrical braking pressure generator which is designed to generate a braking pressure at each of a plurality of wheel brakes, and further having a valve assembly per wheel brake. The valve assembly can be actuated for braking pressure regulation at the corresponding wheel brake in order to couple a first wheel brake associated with the valve assembly either to the first braking pressure generator or to an unpressurized reservoir for hydraulic fluid. The brake system also comprises a second functional unit having at least one second electrical braking pressure generator which is designed to generate a braking pressure at each of a subset of the wheel brakes. The output of the second braking pressure generator is arranged downstream, as seen from the first braking pressure generator, of the valve assembly associated with the corresponding wheel brake. The second functional unit is also designed to perform braking pressure regulation at each wheel brake of the subset redundantly in relation to the first functional unit.

First claim

The invention claimed is:

1. Hydraulic motor vehicle brake system ( 100 - 600 ) with redundant braking pressure regulation, comprising:
a first functional unit ( 110 ) with
at least one first electrical braking pressure generator ( 132 ), which is formed to generate a braking pressure at each of a plurality of wheel brakes (VL, VR, HL, HR);
a first valve arrangement ( 174 , 176 ) per wheel brake (VL), wherein the first valve arrangement ( 174 , 176 ) can be actuated for braking pressure regulation at the corresponding wheel brake (VL), in order to couple a wheel brake (VL) associated with the first valve arrangement ( 174 , 176 ) selectively to the first braking pressure generator ( 132 ) or a first unpressurised reservoir ( 122 ) for hydraulic fluid; and

a second functional unit ( 120 ) with
at least one second electrical braking pressure generator ( 188 ), which is formed to generate a braking pressure at each of a subset of the wheel brakes (VL, VR), wherein an output of the second braking pressure generator ( 188 ) is arranged downstream, as seen from the first braking pressure generator ( 132 ), of the first valve arrangement ( 174 , 176 ) associated with the corresponding wheel brake (VL);
wherein the second functional unit ( 120 ) is designed to carry out braking pressure regulation at each wheel brake (VL, VR) of the subset in a redundant manner in relation to the first functional unit ( 110 );
wherein the second functional unit ( 120 ) comprises at least one fluid reservoir ( 214 , 402 , 702 ) provided on the input side of the second braking pressure generator ( 188 ); wherein
the fluid reservoir is formed as a piston accumulator ( 702 ) with a cylinder ( 704 ) and a piston ( 706 ) taken up movably therein, wherein the piston ( 706 ) has a storage position when the cylinder ( 704 ) is filled and wherein the piston accumulator ( 702 ) is arranged in a fluid path between one of the wheel brakes of the subset and the first functional unit ( 110 ) in such a way that a hydraulic fluid flowing from the wheel brake in the direction of the first functional unit ( 110 ) is able to push the piston ( 706 ) into its storage position; and wherein
a first non-return valve ( 708 ) is provided between the cylinder ( 704 ) and the first functional unit ( 110 ), which permits a flow of hydraulic fluid from the cylinder ( 704 ) into the first functional unit ( 110 ), wherein the first non-return valve ( 708 ) acts in a blocking manner in the opposite direction.

2. Motor vehicle brake system according to claim 1 , wherein both an input of the first braking pressure generator ( 132 ) and an input of the second braking pressure generator ( 188 ) are or can be coupled to the first unpressurised reservoir.

3. Motor vehicle brake system according to claim 1 , wherein the second functional unit ( 110 ) comprises a second unpressurised reservoir ( 124 ) for hydraulic fluid and an input of the second braking pressure generator ( 188 ) is or can be coupled to the second unpressurised reservoir ( 124 ); and wherein an input of the first braking pressure generator ( 132 ) is or can be coupled to the first unpressurised reservoir ( 122 ).

4. Motor vehicle brake system according to claim 3 , wherein the second valve arrangement ( 198 ) is provided between the output of the second braking pressure generator ( 188 ) and the second unpressurised reservoir ( 124 ).

5. Motor vehicle brake system according to claim 1 , wherein the second functional unit ( 120 ) further comprises a second valve arrangement ( 198 , 210 , 214 , 216 , 212 , 302 , 502 ) per wheel brake (VL) of the subset for carrying out braking pressure regulation, wherein the second valve arrangement ( 198 , 210 , 214 , 216 , 212 , 302 , 502 ) can be actuated for braking pressure regulation at the corresponding wheel brake (VL).

6. Motor vehicle brake system according to claim 5 , wherein the second valve arrangement comprises a first valve unit ( 216 ), in order to couple the wheel brake (VL) associated with the second valve arrangement selectively to the second pressure generator ( 188 ) to increase the braking pressure, and a second valve unit ( 218 ), in order to selectively reduce braking pressure at the wheel brake (VL) associated with the second valve arrangement.

7. Motor vehicle brake system according to claim 5 , wherein 40 the second electrical braking pressure generator ( 188 ) is arranged in a fluid line between the first valve arrangement ( 174 , 176 ) associated with a wheel brake (VL) and the corresponding wheel brake (VL) in such a way that the output of the second braking pressure generator ( 188 ) is directed towards the wheel brake (VL) and an input or the input of the second braking pressure generator ( 188 ) is directed towards the corresponding first valve arrangement ( 174 , 176 ).

8. Motor vehicle brake system according to claim 7 , wherein the second valve arrangement associated with the corresponding wheel brake (VL) comprises a first valve unit ( 302 ) connected parallel to the second braking pressure generator ( 188 ).

9. Motor vehicle brake system according to claim 8 , wherein the second valve arrangement associated with the corresponding wheel brake (VL) comprises a second valve unit ( 502 ) connected parallel to the first valve unit ( 302 ).

10. Motor vehicle brake system according to claim 8 , wherein the first and, if present, the second valve unit ( 302 , 502 ) is designed to assume a forward position in operation of the first braking pressure generator ( 132 ) or, in operation of the second braking pressure generator ( 188 ), to assume a blocking position at least opposite to a conveying direction of the second braking pressure generator ( 188 ).

11. Motor vehicle brake system according to claim 1 , wherein the wheel brakes comprise front wheel brakes (VL, VR) and rear wheel brakes (HL, HR), wherein the front wheel brakes (VL, VR) are connected to the second functional unit ( 120 ) and the rear wheel brakes (HR, HL) are connected to the first functional unit ( 110 ).

12. Motor vehicle brake system according to claim 1 , wherein the first non-return valve ( 708 ) is spring-loaded, wherein an opening pressure for opening the first non-return valve ( 708 ) is less than 1 bar.

13. Motor vehicle brake system according to claim 1 , wherein a second non-return valve ( 710 ) is provided, which permits an aspiration of hydraulic fluid by means of the second braking pressure generator ( 188 ) from or via the first functional unit ( 110 ), wherein the second non-return valve ( 710 ) acts in a blocking manner in the opposite direction.

14. Motor vehicle brake system according to claim 1 , wherein the piston accumulator ( 702 ) is formed without an elastic element for automatic transfer of the piston ( 704 ) to its storage position.

15. Motor vehicle brake system according to claim 1 , wherein the second functional unit ( 120 ) further comprises a separating piston arrangement ( 194 ) between the output of the second braking pressure generator ( 188 ) and the corresponding wheel brake (VL) of the subset.

16. Motor vehicle brake system according to claim 15 , wherein the separating piston arrangement ( 194 ) is formed to couple the first braking pressure generator ( 132 ) in its operation fluidically to the corresponding wheel brake (VL) of the subset and in operation of the second braking pressure generator ( 188 ) to uncouple the first braking pressure generator ( 132 ) fluidically from the corresponding wheel brake.

17. Motor vehicle brake system according to claim 1 , wherein the first functional unit (

Assignees

• Lucas Automotive Gmbh

Inventors

• Plewnia Heinrich
• Alford Nicholas

Classifications

• B60T2270/413

  Plausibility monitoring, cross check, redundancy · CPC title

• B60T15/041 Primary

  controlling auxiliary pressure brakes, e.g. parking or emergency brakes (B60T15/048 takes precedence) · CPC title

• B60T2270/404

  Brake-by-wire or X-by-wire failsafe · CPC title

• B60T8/4081 Primary

  Systems with stroke simulating devices for driver input (B60T8/4077 takes precedence) · CPC title