Brake circuit leak detection and isolation

Patent metadata

Field	Value
Publication number	US-10124783-B2
Application number	US-201615341574-A
Country	US
Kind code	B2
Filing date	Nov 2, 2016
Priority date	Nov 2, 2016
Publication date	Nov 13, 2018
Grant date	Nov 13, 2018

Abstract

A method for detecting the location of and isolating a leak in a braking system by simultaneously controlling a direct apply subsystem (DAS) and an isolated apply subsystem (IAS) to enable fluid communication between the IAS and the first circuit; to block fluid communication of the DAS with the first circuit; to enable fluid communication of the DAS with the second circuit; and to block fluid communication of the IAS with the second circuit. A sensed travel of an isolated apply component and a sensed fluid pressure developed by the IAS may be used to determine if the leak is present in the first circuit, while simultaneously using the sensed travel of a direct apply component of the DAS, and a sensed fluid pressure developed by the DAS, to determine if the leak is present in the second circuit.

First claim

What is claimed is:

1. A method for determining a location of and isolating a leak in a braking system for a motor vehicle, the method comprising:
selectively using a direct apply subsystem, which is operably associated with a brake pedal of the vehicle, and an isolated apply subsystem, to control an application of fluid to a first circuit and a second circuit;
operating in a leak location detection mode to detect a location of the leak by simultaneously controlling the direct apply subsystem and the isolated apply subsystem to:
enable fluid communication between the isolated apply subsystem and the first circuit of the braking system;
blocking fluid communication of the direct apply subsystem with the first circuit;
enable fluid communication of the direct apply subsystem with the second circuit of the braking system;
block fluid communication of the isolated apply subsystem with the second circuit; and
using an input signal associated with a sensed travel of an isolated apply component of the isolated apply subsystem, and a sensed fluid pressure developed by the isolated apply subsystem to determine if the leak is present in the first circuit, and simultaneously using the sensed travel of the direct apply component and a sensed fluid pressure developed by the direct apply subsystem to determine if the leak is present in the second circuit.

2. The method of claim 1 , further comprising:
upon condition the leak is determined to be located in the first circuit, selectively place the braking system in a first circuit isolation mode, in which the first circuit is isolated and braking is accomplished exclusively using the second circuit; and
upon condition the leak is determined to be located in the second circuit selectively place the braking system in a second circuit isolation mode, in which the second circuit is isolated and braking is accomplished exclusively using the first circuit.

3. The method of claim 1 , wherein the determining if the leak is present in at least one of the first or second circuits comprises:
considering the sensed fluid pressure developed by the isolated apply subsystem and the sensed travel of the isolated apply component; and
when the sensed fluid pressure developed by the isolated apply subsystem is less than a predetermined value, based on the sensed travel of the isolated apply component, determining that a leak is present in the first circuit of the braking system.

4. The method of claim 3 , further comprising:
upon determining that the leak is present in the first circuit, operating the braking system of the vehicle in a first circuit isolation mode by:
blocking fluid communication of the isolated apply subsystem and the direct apply subsystem with the first circuit of the braking system; and
enabling fluid communication of the isolated apply portion and blocking communication of the direct apply subsystem with the second circuit of the braking system.

5. The method of claim 4 , further comprising:
when operating in the first circuit isolation mode:
closing a first master cut valve associated with the first circuit to block fluid communication of the first circuit with the direct apply subsystem;
closing a first apply valve associated with the first circuit to block fluid communication of the first circuit with the isolated apply subsystem;
closing a second master cut valve associated with the second circuit to block fluid communication of the second circuit with the direct apply subsystem; and
opening a second apply valve associated with the second circuit to allow fluid communication of the second circuit with the isolated apply subsystem.

6. The method of claim 3 , wherein the determining if the leak is present in at least one of the first or second circuits comprises:
considering the sensed fluid pressure developed by the direct apply subsystem and the sensed travel of the direct apply component, wherein the direct apply component is a brake pedal; and
when the sensed fluid pressure developed by the direct apply subsystem is less than a predetermined value, determining that a leak is present in the second circuit of the braking system.

7. The method of claim 6 , further comprising:
upon determining that the leak is present in the second circuit, operating the braking system of the vehicle in a second circuit isolation mode by:
blocking fluid communication of the isolated apply subsystem and the direct apply subsystem with the second circuit of the braking system; and
enabling fluid communication of the isolated apply subsystem and blocking communication of the direct apply subsystem with the first circuit of the braking system.

8. The method of claim 7 , further comprising:
when operating in the second circuit isolation mode:
closing a first master cut valve associated with the first circuit to block fluid communication of the first circuit with the direct apply subsystem;
opening a first apply valve associated with the first circuit to allow fluid communication of the first circuit with the isolated apply subsystem;
closing a second master cut valve associated with the second circuit to block fluid communication of the second circuit with the direct apply subsystem; and
closing a second apply valve associated with the second circuit to block fluid communication of the second circuit with the isolated apply subsystem.

9. The method of claim 1 , further comprising:
prior to performing operations to detect the location of the leak:
operating in a normal mode in which fluid communication of the isolated apply subsystem with the first circuit and the second circuit is enabled, and fluid communication of the direct apply subsystem with the first circuit and the second circuit is blocked;
using a sensed travel of the isolated apply component and a sensed fluid pressure developed by the isolated apply subsystem in response to a command based on a travel of the direct apply component, to determine if a leak is present in at least one of the first or second circuits, and:
if the sensed fluid pressure developed by the isolated apply subsystem is less than a predetermined value corresponding to the sensed travel of the isolated apply component, determining that a leak is present and proceeding to detect whether the leak is present in the first circuit or the second circuit; and
if the sensed fluid pressure developed by the isolated apply subsystem is greater than or equal to the predetermined value, then continuing operating in the normal mode.

10. The method of claim 9 , further comprising:
when in the normal mode of operation:
closing a first master cut valve associated with the first circuit and a second master cut valve associated with the second circuit to block fluid communication of both of the first circuit and the second circuit with the direct apply subsystem; and
opening a first apply valve associated with the first circuit and a second apply valve associated with the second circuit to allow fluid communication of both of the first circuit and the second circuit with the isolated apply subsystem.

11. The method of claim 1 , wherein
the direct apply subsystem includes a dual output master cylinder mechanically coupled to and actuated by the brake pedal, with a first output of the dual output master cylinder in fluid communication with a first master cut valve associated with the first circuit, and a second output of the dual output master cylinder in fluid communication with a second master cut valve associated with the second circuit; and
the isolated apply subsystem includes at least one of:
a single output slave cylinder having the isolated apply component, and wherein the single output slave cylin

Assignees

• Autoliv Asp Inc
• Veoneer Nissin Brake Sys Japan Co Ltd

Inventors

• Spieker Arnold H

Classifications

• B60T2270/406

  Test-mode; Self-diagnosis · CPC title

• B60T8/4081

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

• B60T13/142

  Systems with master cylinder · CPC title

• B60T7/042

  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