Vehicle braking system with ABS emulation

Patent metadata

Field	Value
Publication number	US-10479335-B2
Application number	US-201715852107-A
Country	US
Kind code	B2
Filing date	Dec 22, 2017
Priority date	Dec 22, 2017
Publication date	Nov 19, 2019
Grant date	Nov 19, 2019

Abstract

A vehicle braking system includes a wheel cylinder, a brake pedal, a master cylinder, a master cylinder circuit, a primary braking unit operable to generate a braking force at the wheel cylinder in a primary mode, decoupled from the master cylinder circuit, a secondary braking unit including a second electrically-actuated pressure generating unit and operable to generate a braking force at the wheel cylinder in a secondary mode of operation, a plurality of valves configured to provide anti-lock braking at the wheel cylinder upon loss of traction during braking in the primary mode of operation, and a controller programmed to actuate the plurality of valves and further programmed to actuate the second electrically-actuated pressure generating unit upon loss of traction in the primary mode of operation to generate pulsations within the master cylinder circuit to provide a feedback force at the brake pedal indicative of the anti-lock braking.

First claim

What is claimed is:

1. A vehicle braking system comprising:
a wheel cylinder;
a brake pedal;
a master cylinder configured to receive an input from the brake pedal;
a master cylinder circuit connected to the master cylinder;
a primary braking unit including a first electrically-actuated pressure generating unit distinct from the master cylinder and operable to generate a braking force at the wheel cylinder in a primary mode of operation, decoupled from the master cylinder circuit;
a secondary braking unit including a second electrically-actuated pressure generating unit distinct from the master cylinder and operable to generate a braking force at the wheel cylinder in a secondary mode of operation;
a plurality of valves configured to transition between open and closed positions to provide anti-lock braking at the wheel cylinder upon loss of traction during braking in the primary mode of operation; and
a controller programmed to actuate the plurality of valves and further programmed to actuate the second electrically-actuated pressure generating unit upon loss of traction in the primary mode of operation to generate pulsations within the master cylinder circuit to provide a feedback force at the brake pedal indicative of the anti-lock braking.

2. The vehicle braking system of claim 1 , wherein the plurality of valves are configured to transition between open and closed positions to provide anti-lock braking at the wheel cylinder upon loss of traction in the primary mode of operation and the secondary mode of operation.

3. The vehicle braking system of claim 1 , wherein the feedback force is a pulsation such that the second electrically-actuated pressure generating unit is operable to provide a pulsation at the brake pedal.

4. The vehicle braking system of claim 3 , wherein the plurality of valves are operable by the controller to generate a pulsation at the wheel cylinder upon the controller detecting loss of traction in the first mode of operation, and wherein the magnitude and frequency of the pulsation at the brake pedal is independent of the magnitude and the frequency of the pulsation at the wheel cylinder.

5. The vehicle braking system of claim 4 , further comprising a wheel cylinder circuit connected to the wheel cylinder, and a separation valve between the wheel cylinder circuit and the master cylinder circuit, wherein, upon the controller detecting loss of traction in the first mode of operation, the controller is programmed to close the separation valve such that the pulsation at the wheel cylinder does not affect the pulsation at the brake pedal.

6. The vehicle braking system of claim 1 , wherein the second electrically-actuated pressure generating unit includes a pump, wherein, upon the controller detecting loss of traction in the primary mode of operation, the controller is programmed to operate the pump to provide pressure pulsations at the master cylinder, thereby generating the feedback force.

7. The vehicle braking system of claim 6 , further comprising an inlet valve of the secondary braking unit located between an outlet side of the pump and the master cylinder, wherein, upon the controller detecting loss of traction in the primary mode of operation, the controller is programmed to open the inlet valve.

8. The vehicle braking system of claim 7 , wherein, in the secondary mode of operation, the inlet valve is in a closed position.

9. The vehicle braking system of claim 6 , further comprising an inlet valve of the secondary braking unit located between an outlet side of the pump and the master cylinder, wherein, upon the controller detecting loss of traction in the primary mode of operation, the controller is programmed to pulse the inlet valve between an open position and a closed position.

10. A method of operating a vehicle braking system, the method comprising:
electrically actuating a brake-by-wire braking unit to generate a braking force at a wheel cylinder;
modulating a valve with a controller to introduce pressure pulsations into the braking force at the wheel cylinder, defining an anti-lock braking force; and
electrically actuating a secondary braking unit, separate from the brake-by-wire braking unit, to generate a feedback force at a brake pedal while a master cylinder is decoupled from the wheel cylinder, the feedback force separate from the anti-lock braking force and provided in response to the introduction of pressure pulsations at the wheel cylinder.

11. The method of claim 10 , wherein the secondary braking unit includes a pump, and wherein actuating the secondary braking unit includes electrically actuating a pump to cycle fluid between an outlet of the pump and an inlet of the pump.

12. The method of claim 11 , further comprising a first valve and a second valve in parallel with the first valve between a master cylinder and the pump, wherein the first and second valves are open when electrically actuating the secondary braking unit to generate the feedback force at the brake pedal.

13. The method of claim 10 , wherein electrically actuating the secondary braking unit to generate the feedback force at the brake pedal includes producing a pedal pulsation via the feedback force.

14. The method of claim 10 , wherein a separation valve located between the secondary braking unit and the primary braking unit is closed prior to electrically actuating the secondary braking unit to generate the feedback force such that the fluid used to generate the feedback force is separated from the fluid used to generate the anti-lock braking force at the wheel cylinder.

15. The method of claim 10 , wherein the feedback force is a first feedback force at the brake pedal and generates a pulsation, the method further comprising actuating a pedal feel simulator to provide a second feedback force at the brake pedal, the second feedback force dependent upon a fixed spring constant of the pedal feel simulator.

16. A vehicle braking system comprising:
a wheel cylinder;
a brake pedal configured to receive a user input;
a master cylinder configured to receive an input from the brake pedal; and
a motor-driven pump operable to selectively provide fluid pressure to generate a feedback force to the brake pedal in a first braking mode in which the motor-driven pump is decoupled from the wheel cylinder,
wherein the motor-driven pump is operable to generate a braking force at the wheel cylinder in a second braking mode.

17. The vehicle braking system of claim 16 , wherein, in the first braking mode, a brake-by-wire braking unit separate from the motor-driven pump and the master cylinder is configured to generate a braking force at the wheel cylinder.

18. The vehicle braking system of claim 17 , wherein the brake-by-wire braking unit includes at least one valve operable to be manipulated to generate an anti-lock braking pulsation at the wheel cylinder in the first braking mode, wherein, in the first braking mode, the motor-driven pump is operable to provide the anti-lock braking pulsation at the brake pedal in conjunction with manipulation of the valve.

19. The vehicle braking system of claim 16 , wherein the first mode includes an ABS scenario and a non-ABS scenario, wherein the motor-driven pump is operable to provide the pulsation in the ABS scenario and is not operable to provide the pulsation in the non-ABS scenario.

20. The vehicle braking system of claim 16 , further comprising a pedal feel simulator operable to provide a feedback force to the brake pedal according to a fixed spring constant in the first braki

Assignees

• Bosch Gmbh Robert

Inventors

• Kuhlman Ryan
• Hansmann Simon

Classifications

• B60T2270/404

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

• B60T8/176

  Brake regulation specially adapted to prevent excessive wheel slip during vehicle deceleration, e.g. ABS (B60T8/1755 takes precedence) · CPC title

• B60T7/042 Primary

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

• B60T13/745

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

• B60T13/662

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