Vehicle brake device

A vehicle brake device, comprising:

• a wheel cylinder for receiving a hydraulic pressure of a working fluid and applying a braking force to a wheel;
• 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 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 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 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 the wheel cylinders provided on a front wheel side of a vehicle and the wheel cylinders provided on a rear wheel side of the vehicle, switch the respective wheel cylinders provided for front right and left wheels of the vehicle to a communication state where the wheel cylinders communicate to the master cylinder independently from each other, and switch the wheel cylinders provided for rear right and left wheels of the vehicle to a communication state where the wheel cylinders 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 the communication state 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 communication state 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 on the front right wheel, a brake system for the front left wheel for providing communication between the master cylinder and the wheel cylinder on 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 on 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 communication state 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 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.