Method for controlling a hydraulic brake system of a motor vehicle

Patent metadata

Field	Value
Publication number	US-2016200309-A1
Application number	US-201614990489-A
Country	US
Kind code	A1
Filing date	Jan 7, 2016
Priority date	Jan 8, 2015
Publication date	Jul 14, 2016
Grant date	—

Abstract

A method of controlling a brake system of a motor vehicle having a braking assistance function. The brake system including a master brake cylinder, activated with a brake pedal. A distance s between a valve piston connected to the brake pedal, and a transmission element, connected to a pressure piston of the master brake cylinder is sensed and the brake system is controlled as a function of the sensed distance s. Within the scope of this monitoring process, brake pedal release is detected even when the pressure-generating unit is activated. In addition, despite an active braking assistance function, consistent interplay occurs between activation by the driver and assistance-side activation of the brakes given satisfactory pedal feedback.

First claim

What is claimed is:

1 . A method for controlling a hydraulic brake system comprising:
providing a master brake cylinder having a pressure piston and a transmission element connected to the pressure piston; providing a valve piston spaced from said pressure piston a distance s wherein the distance s is sensed; and controlling the brake system as a function of the sensed distance s.

2 . The method of claim 1 wherein the transmission element is a reaction disk of a brake booster.

3 . The method of claim 1 including the steps of:
determining a distance s 0 between the valve piston and the transmission element in the case of non-activation of a brake pedal;
comparing the current distance s between the valve piston and the transmission element with the distance s 0 ; and
when the condition s−s 0 =0 applies, a released brake pedal is inferred.

4 . The method of claim 1 including the step of generating an increase in brake pressure by a pressure-generating device of an electronic stability control system (ESC).

5 . The method of claim 1 including the step of generating an increase in brake pressure by a brake booster.

6 . The method of claim 1 including the steps of:
determining when a pressure-generating device of an electronic stability control system brings about an increase in pressure;
sensing a change in the distance s over time; and
actuating a brake booster to increase brake pressure in the event of an increase in the distance s.

7 . The method of claim 1 including the steps of:
determining whether a brake assistance function is activated;
when a brake assistance function is activated determining whether the distance s changes over time;
operating a brake booster to increase brake pressure; and
operating the brake booster in a manner corresponding to the change in distance s.

8 . The method of claim 7 including the steps of:
determining whether the distance s is greater than or less than the distance s 0 ;
operating the brake booster at a predetermined rate when the distance s is greater than the distance s 0 ; and
when the distance s is less than the distance s 0 operating the brake booster at a rate less than the rate of operation of the brake booster when the distance s is greater than the distance s 0 .

9 . The method of claim 8 wherein when the distance s is less than the distance s 0 the rate of operation of brake booster is reduced by approximately 20%.

10 . A method for controlling a hydraulic brake system of a motor vehicle having a braking assistance function comprising:
providing a master brake cylinder having a pressure piston and a transmission element connected to the pressure piston; providing a brake booster having a valve piston and a valve body, said valve body engaging said transmission element; said valve piston spaced from said transmission element a distance s apart from one another; determining a distance s 0 between the valve piston and the transmission element; comparing the distance s between the valve piston and the transmission element with the distance s 0 ; and moving said valve body of said brake booster to increase brake pressure corresponding to the comparison between the distance s and the distance s 0 wherein the brake system is controlled as a function of the sensed distance s.

11 . The method of claim 10 including the step of determining whether a brake assist function is activated.

12 . The method of claim 10 including the steps of:
determining whether a brake assistance function is activated;
when a brake assistance function is activated determining whether the distance s changes over time;
determining whether the distance s is greater than or less than the distance s 0 ;
operating the brake booster at a predetermined rate when the distance s is greater than the distance s 0 ; and
when the distance s is less than the distance s 0 operating the brake booster at a rate less than the rate of operation of the brake booster when the distance s is greater than the distance s 0 .

13 . The method of claim 10 wherein when the distance s is less than the distance s 0 the rate of operation of brake booster is reduced by an amount greater than 10%.

14 . The method of claim 10 including the steps of:
providing a brake booster body engaging said valve body;
providing a drive motor, said drive motor engaging said brake booster body;
actuating said drive motor to move said valve body and correspondingly increase said brake pressure.

15 . A hydraulic brake system comprising:
a master brake cylinder including a pressure piston; a brake booster including a valve body and a valve piston; a transmission element disposed between said valve body and said pressure piston, said transmission element spaced at a predetermined distance s from said valve piston; and at least one sensor for sensing the distance s.

16 . A hydraulic brake system as set forth in claim 15 including:
a brake booster body engaging said valve body; and
a drive member, said drive member engaging said brake booster body and operative to move said brake booster body and correspondingly said valve body.

Assignees

• Ford Global Tech Llc

Inventors

• Svensson Thomas

Classifications

• B60T8/172

  Determining control parameters used in the regulation, e.g. by calculations involving measured or detected parameters {(B60T8/17551 takes precedence)} · CPC title

• B60T13/686

  in hydraulic systems or parts thereof · CPC title

• B60T13/745 Primary

  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

• B60T7/12

  for automatic initiation; for initiation not subject to will of driver or passenger {(limiting speed of vehicles other than rail vehicles B60K31/00)} · CPC title