Technique for determining the position of a support point of a parking brake unit

Patent metadata

Field	Value
Publication number	US-10933848-B2
Application number	US-201716330480-A
Country	US
Kind code	B2
Filing date	Aug 1, 2017
Priority date	Sep 8, 2016
Publication date	Mar 2, 2021
Grant date	Mar 2, 2021

Abstract

A method for operating a vehicle brake, wherein the vehicle brake comprises a service brake having an actuating piston, which can be moved into an actuation position in order to produce a braking force by the action of a hydraulic pressure, and wherein the vehicle brake also comprises a parking brake unit, which is designed to move over a first motion range without producing a braking force and is also designed to move over a second motion range, in which the parking brake unit is supported against the actuating piston and a braking force is thus changed, wherein the first and second motion ranges transition into each other at a support point, wherein the method is performed in the pressureless state or at a hydraulic pressure below a predefined threshold value and comprises the following steps: a) moving the parking brake unit from the first into the second motion range or vice versa; b) recording the curve of an operating parameter of the parking brake unit during step a); and c) determining the position of the support point on the basis of the curve of the operating parameter.

First claim

The invention claimed is:

1. A method for operating a vehicle brake comprising the following steps of:
advancing a parking brake unit from a first movement range where no brake force is generated into a second movement range where a brake force is generated due to an actuating piston and a spindle moving in a first direction;
detecting a course of an operating parameter of the parking brake unit while moving the parking brake unit from the first movement range to the second movement range; and
determining a position of a support point by means of the course of the operating parameter;
wherein the support point is deemed to be the position of the parking brake unit when the brake force is initially generated due to the actuating piston and spindle advancing in the first direction and wherein the operating parameter is at least one of a motor current of an electromotive drive unit or a speed of the electromotive drive unit; and
wherein the position of the support point is stored as a linear distance between the support point and a reference point wherein the support point is identified via the operating parameter.

2. The method according to claim 1 , wherein the parking brake unit advances relative to the reference point and subsequently retracts relative to the position of the support point; and
wherein the position of the support point has been stored as the linear distance between the support point and the reference point.

3. The method according to claim 2 , wherein the method further comprises the following steps of:
storing the position of the support point in a controller of the vehicle brake; and
using the determined position of the support point to influence a release of the parking brake unit.

4. The method according to claim 3 , wherein the release of the parking brake unit includes a retraction of the parking brake unit from the second movement range at least up to the support point where the brake force is reduced to zero.

5. The method according to claim 4 , wherein the release of the parking brake unit includes a retraction of the parking brake unit beyond the support point so that the parking brake is in the first movement range.

6. The method according to claim 5 , wherein the retraction of the parking brake unit from the second movement range and into the first movement range is determined by a predetermined brake clearance.

7. The method according to claim 5 , wherein the retraction of the parking brake unit from the second movement range into the first movement range is determined by a predetermined safety distance between the parking brake unit and the actuating piston.

8. The method according to claim 5 , wherein the retraction of the parking brake unit from the second movement range into the first movement range takes place over a retraction distance which is defined as the predetermined distance to the support point.

9. The method according to claim 1 , wherein the parking brake unit includes an electromotive drive unit and an actuator unit interacting with the actuating piston, and
wherein the electromotive drive unit is configured to extend the actuator unit over the first movement range and into the second movement range.

10. The method according to claim 9 , wherein the actuator unit comprises a nut/spindle arrangement and the position of the support point is defined as a function of at least one of the following parameters:
position information of the spindle nut relative to the reference point;
a path distance of the spindle nut relative to the reference point; or
a number of revolutions of the nut/spindle arrangement.

11. The method according to claim 1 , wherein the method further comprises the following step:
further advancing the parking brake unit from another first movement range where no brake force is generated into another second movement range where another brake force is generated due to the actuating piston and the spindle further advancing in the first direction;
monitoring the operating parameter of the parking brake unit while advancing the parking brake unit from the another first movement range to the another second movement range; and
determining an updated position of the support point via the operating parameter;
repeatedly performing the steps of advancing the parking brake from the another first movement range to the another second movement range, monitoring the operating parameter, and determining the updated position of the support point until at least one of the following criteria is met: expiry of a predetermined time interval; attainment of a predetermined driving performance of the vehicle; attainment of a predetermined operating duration of the vehicle; or attainment of a predetermined braking performance of the vehicle.

12. The method according to claim 11 , wherein the attainment of the predetermined driving performance of the vehicle is a predetermined distance covered by the vehicle and the attainment of a predetermined braking performance of the vehicle is a predetermined number of braking operations of the vehicle.

13. The method according to claim 1 , wherein the method further comprises the following steps:
actuating the parking brake unit so as to generate a brake force independently of a driver by overcoming a brake clearance; and
releasing the parking brake unit via retraction of the nut/spindle to dissipate the brake force;
wherein the step of releasing the parking brake is executed according to the position of the support point.

Assignees

• Lucas Automotive Gmbh
• Zf Active Safety Gmbh

Inventors

• Bast Michael
• Ohlig Benedikt
• Fuchs Matthias
• Michels Erwin

Classifications

• B60T13/588 Primary

  both fluid and mechanical assistance or drive · CPC title

• F16D2123/00

  Multiple operation forces · CPC title

• F16D66/021

  using electrical detection or indication means · CPC title

• F16D65/18

  adapted for drawing members together {, e.g. for disc brakes} · CPC title

• B60T13/741

  acting on an ultimate actuator · CPC title