Method for operating a hydraulic brake system

Patent metadata

Field	Value
Publication number	US-9308904-B2
Application number	US-201414218588-A
Country	US
Kind code	B2
Filing date	Mar 18, 2014
Priority date	Mar 18, 2013
Publication date	Apr 12, 2016
Grant date	Apr 12, 2016

Abstract

A method of operating a hydraulic brake system is described. A method of operating a hydraulic brake system of a motor vehicle having a mechatronic brake booster to boost a hydraulic pressure generated in a brake master cylinder of the brake system by a brake pedal of the motor vehicle determines whether a propulsion request is present during operation of the motor vehicle and actuates the mechatronic brake booster when a propulsion request has ended or been substantially reduced. During a predetermined time interval after the propulsion request has ended or been reduced, the mechatronic brake booster is operated at a minimum intensity such that no braking effect occurs during the predetermined time interval, unless a braking request occurs.

First claim

What is claimed is:

1. A method of operating a hydraulic brake system of a motor vehicle having a mechatronic brake booster to boost a hydraulic pressure generated in a brake master cylinder of the brake system by a brake pedal of the motor vehicle, the method comprising:
determining whether a propulsion request is present during operation of the motor vehicle; and
actuating the mechatronic brake booster when a propulsion request has ended or been substantially reduced;
wherein, during a predetermined time interval after the propulsion request has ended or been reduced, the mechatronic brake booster is operated at a minimum intensity such that no braking effect occurs during the predetermined time interval, unless a braking request occurs.

2. The method as claimed in claim 1 , wherein determining whether a propulsion request is present includes continuously monitoring a status of an accelerator pedal.

3. The method as claimed in claim 1 , wherein the predetermined time interval is about two or more seconds.

4. The method as claimed in claim 1 , wherein the predetermined time interval ranges from about two seconds to about five seconds.

5. The method as claimed in claim 1 , wherein the ending or reduction of the propulsion request occurs when an accelerator pedal of the motor vehicle is released.

6. The method as claimed in claim 1 , wherein the mechatronic brake booster comprises an electric motor to exert an additional force on a hydraulic piston of the brake mechatronic booster parallel to a force exerted on the hydraulic piston via the brake pedal.

7. The method as claimed in claim 6 , wherein the electric motor is operated at a minimum speed and/or a minimum torque during the predetermined time interval such that no braking effect occurs during the predetermined time interval unless a braking request occurs.

8. The method as claimed in claim 6 , wherein, when the propulsion request is ended or reduced, the electric motor rotates a short distance such that no braking effect occurs during the predetermined time interval, unless a braking request occurs during the predetermined time interval, and the electric motor remains stationary with a non-zero current supply insufficient to rotate the motor for a remainder of the predetermined time interval.

9. The method as claimed in claim 8 , wherein after the predetermined time interval has elapsed the electric motor rotates back to a starting position of the electric motor.

10. The method as claimed in claim 1 , wherein the determining is continuously conducted during the operation of the motor vehicle.

11. A method of operating a hydraulic brake system of a motor vehicle having a mechatronic brake booster, the method comprising:
during operation of the motor vehicle, monitoring a status of a propulsion request; and
actuating the mechatronic brake booster when a propulsion request has ended or been substantially reduced;
wherein, during a predetermined time interval after the propulsion request has ended or been reduced, the mechatronic brake booster is operated at a minimum intensity such that no braking effect occurs and stiffness of brake pedal of the motor vehicle is decreased.

12. A hydraulic brake system of a motor vehicle, comprising:
a mechatronic brake booster comprising:
a brake master cylinder configured to generate a hydraulic pressure corresponding to a depression of a brake pedal of a motor vehicle, and
an electric motor configured to generate an auxiliary braking force for the master cylinder; and

a controller configured to monitor a status of a propulsion request during operation of the motor vehicle;
wherein the controller is configured to actuate the electric motor at a minimum intensity such that no braking effect occurs when the propulsion request has ended or been substantially reduced.

13. The hydraulic brake system of claim 12 , wherein, upon actuation of the electric motor, the controller is configured to operate the electric motor at a minimum intensity for a predetermined time interval unless a braking request occurs.

14. A method of operating a hydraulic brake system of a motor vehicle having a mechatronic brake booster, the method comprising:
monitoring a position of an accelerator pedal;
upon detection of an accelerator pedal release rate exceeding a release rate threshold, actuating a motor of the mechatronic brake booster;
closing pressure feed valves in the brake system;
controlling a speed of the motor to build a head pressure; and
opening the pressure feed valves in response to a braking request or expiration of a predetermined time interval.

15. The method of claim 14 , wherein the braking request includes driver input or external sensor input.

16. The method of claim 14 , wherein actuation of the motor and closing the pressure feed valves occur substantially simultaneously.

17. The method of claim 14 , wherein building a head pressure includes building a head pressure of between about 40 bar and about 70 bar.

18. The method of claim 14 , wherein actuating the motor includes running the motor at a speed of less than 1% of a maximum motor speed.

19. The method of claim 14 , further comprising, prior to closing the pressure feed valves, building a hydraulic fluid pressure of about 1.5 bar to about 3.0 bar at wheel brakes of the vehicle.

20. The method of claim 14 , wherein controlling a speed of the motor to build a head pressure includes running the motor at a speed of between about 1% and about 30% of a maximum motor speed.

21. The method of claim 14 , wherein the predetermined time interval is between about two seconds and about twenty seconds.

22. A hydraulic brake system of a motor vehicle, comprising:
a mechatronic brake booster including an electric motor;
at least one wheel brake;
at least one pressure feed valve configured to control flow of hydraulic brake fluid to the at least one wheel brake; and
a controller configured to run the electric motor and close the at least one pressure feed valve in response to an accelerator pedal release rate exceeding a release rate threshold.

Assignees

• Ford Global Tech Llc

Inventors

• Svensson Thomas

Classifications

• B60T8/3275

  Systems with a braking assistant function, i.e. automatic full braking initiation in dependence of brake pedal velocity · CPC title

• B60T8/3265 Primary

  with control of the booster (B60T8/3275 takes precedence) · CPC title

• B60T2201/12

  Pre-actuation of braking systems without significant braking effect; Optimizing brake performance by reduction of play between brake pads and brake disc · 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