Vehicle brake device

Patent metadata

Field	Value
Publication number	US-9656650-B2
Application number	US-201214390561-A
Country	US
Kind code	B2
Filing date	Apr 5, 2012
Priority date	Apr 5, 2012
Publication date	May 23, 2017
Grant date	May 23, 2017

Abstract

A brake ECU brings master cut valves into an open state and brings holding valves into a closed state, thereby controlling a master cylinder and wheel cylinders to communicate to each other when a magnitude of a hydraulic pressure detected by an accumulator pressure sensor has decreased to a value less than a predetermined value set in advance. On the other hand, the ECU maintains holding valves in an open state, and controls an accumulator and the wheel cylinders to communicate to each other via linear control valves. Then, the ECU determines in which brake system a failure occurs out of a brake system for a front right wheel, a brake system for a front left wheel, and brake systems for rear right and left wheels based on changes in hydraulic pressure detected by a sensor, a master cylinder pressure sensor, and a control pressure sensor.

First claim

The invention claimed is:

1. A vehicle brake device, comprising:
a first wheel cylinder for receiving a hydraulic pressure of a working fluid and applying a braking force to a wheel, that is among a plurality of wheel cylinders of a vehicle;
a master cylinder for introducing therein a servo pressure generated in response to an operation by a driver on a brake pedal thereby generating a hydraulic pressure;
a power hydraulic pressure source for generating a hydraulic pressure by drive of a pressurizing pump;
a linear control valve for adjusting the hydraulic pressure transmitted from the power hydraulic pressure source to the first wheel cylinder;
first hydraulic pressure detection means for detecting the hydraulic pressure output from the power hydraulic pressure source;
second hydraulic pressure detection means for detecting the hydraulic pressure output from the master cylinder;
third hydraulic pressure detection means for detecting the hydraulic pressure in the first wheel cylinder; and
control means for controlling drive of the linear control valve based on the hydraulic pressure output from the master cylinder and detected by the second hydraulic pressure detection means, and the hydraulic pressure in the first wheel cylinder detected by the third hydraulic pressure detection means, wherein:
the control means is configured to:
shut off, when a magnitude of the hydraulic pressure output from the power hydraulic pressure source and detected by the first hydraulic pressure detection means has decreased to a value less than a predetermined value set in advance, communication between wheel cylinders provided for front right and left wheels among the plurality of wheel cylinders of the vehicle and wheel cylinders provided for rear right and left wheels among the plurality of wheel cylinders of the vehicle, switch the wheel cylinders provided for the front right and left wheels to a first communication state where the wheel cylinders provided for the front right and left wheels communicate to the master cylinder independently from each other, and switch the wheel cylinders provided for the rear right and left wheels to a second communication state where the wheel cylinders provided for the rear right and left wheels communicate via the linear control valve to the power hydraulic pressure source; and
determine, based on a change in hydraulic pressure which continues to decrease without turning to increase and recovering after at least one of the first and second communication states is switched out of changes in hydraulic pressures detected by the first hydraulic pressure detection means, the second hydraulic pressure detection means, and the third hydraulic pressure detection means after the at least one of the first and second communication states is switched, in which brake system such a failure that the hydraulic pressure of the working fluid is unable to be transmitted occurs out of a brake system for the front right wheel for providing communication between the master cylinder and the wheel cylinder provided for the front right wheel, a brake system for the front left wheel for providing communication between the master cylinder and the wheel cylinder provided for the front left wheel, and brake systems for the rear right and left wheels for providing communication between the power hydraulic pressure source and the wheel cylinders provided for the rear right and left wheels;

the second hydraulic pressure detection means communicates to the brake system for the front right wheel or the brake system for the front left wheel; and
the control means determines, after the at least one of the first and second communication states is switched, when at least the hydraulic pressures detected by the first hydraulic pressure detection means and the second hydraulic pressure detection means turn to increase and recover, that the failure occurs in a brake system not communicating to the second hydraulic pressure detection means out of the brake systems for the front right wheel and the front left wheel.

2. A vehicle brake device according to claim 1 , wherein the control means is configured to:
maintain, when the control means determines that the failure occurs in the brake system not communicating to the second hydraulic pressure detection means out of the brake systems for the front right wheel and the front left wheel, communication between the master cylinder and a wheel cylinder among the plurality of wheel cylinders of the vehicle that is in a brake system communicating to the second hydraulic pressure detection means, and shut off communication between the master cylinder and a wheel cylinder among the plurality of wheel cylinders of the vehicle that is in the brake system not communicating to the second hydraulic pressure detection means; and
maintain communication between the first wheel cylinder and the power hydraulic pressure source via the linear control valve in a brake system on a diagonal position side with respect to the brake system communicating to the second hydraulic pressure detection means out of the brake systems for the rear right and left wheels, and shut off communication between a second wheel cylinder among the plurality of wheel cylinders of the vehicle and the power hydraulic pressure source via the linear control valve in a brake system on a diagonal position side with respect to the brake system not communicating to the second hydraulic pressure detection means.

3. A vehicle brake device according to claim 1 , wherein the control means determines, after the at least one of the first and second communication states is switched, when at least the hydraulic pressure detected by the first hydraulic pressure detection means turns to increase and recovers while the hydraulic pressure detected by the second hydraulic pressure detection means continues to decrease without turning to increase and recovering, that the failure occurs in a brake system communicating to the second hydraulic pressure detection means out of the brake systems for the front right and left wheels.

4. A vehicle brake device according to claim 3 , wherein the control means is configured to:
maintain, when the control means determines that the failure occurs in the brake system communicating to the second hydraulic pressure detection means out of the brake systems for the front right wheel and the front left wheel, communication between the master cylinder and a wheel cylinder among the plurality of wheel cylinders of the vehicle that is in the brake system not communicating to the second hydraulic pressure detection means, and shut off communication between the master cylinder and a wheel cylinder among the plurality of wheel cylinders of the vehicle that is in the brake system communicating to the second hydraulic pressure detection means; and
maintain communication between the first wheel cylinder and the power hydraulic pressure source via the linear control valve in a brake system on a diagonal position with respect to the brake system not communicating to the second hydraulic pressure detection means out of the brake systems for the rear right and left wheels, and shut off communication between a second wheel cylinder among the plurality of wheel cylinders of the vehicle and the power hydraulic pressure source via the linear control valve in a brake system on a diagonal position side with respect to the brake system not communicating to the second hydraulic pressure detection means.

5. A vehicle brake device according to claim 1 , wherein the control means determines, after the at least one of the first and second communication states is switched, when at least the hydraulic pressure detected by the first hydraulic pressure detection means continues to decrease without turning to increase and recovering while the hydraulic p

Assignees

• Yamasaki Tsuyoshi
• Ohkubo Masayasu
• Toyota Motor Co Ltd

Inventors

• Yamasaki Tsuyoshi
• Ohkubo Masayasu

Classifications

• B60T13/686 Primary

  in hydraulic systems or parts thereof · CPC title

• B60T7/042

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

• B60T13/142

  Systems with master cylinder · CPC title

• B60T8/4081

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

• B60T13/146

  Part of the system directly actuated by booster pressure · CPC title