Patent ID: 7837280

Claim:
A vehicle brake system for applying braking force to a plurality of wheels of a vehicle, comprising: a wheel cylinder, provided at each wheel, that produces the braking force by using hydraulic pressure; a hydraulic pressure source that supplies hydraulic fluid that has been pressurized; a hydraulic pressure supply passage that supplies hydraulic pressure from the hydraulic pressure source to the wheel cylinder; a pressure increase control valve, which is disposed in the hydraulic pressure supply passage, that supplies hydraulic pressure from the hydraulic pressure source to the wheel cylinder according to operation of a brake pedal; a communication valve that is placed in a channel of the hydraulic fluid extending from the pressure increase control valve to the wheel cylinder, and that separates the channel, as needed, into an upstream-side first passage that communicates with at least one wheel cylinder, and a downstream-side second passage that communicates with the wheel cylinder other than the wheel cylinder that communicates with the first passage, wherein the first passage is closer to the pressure increase control valve than the second passage; a pressure-reducing passage that discharges the hydraulic fluid from the wheel cylinder; a pressure reduction control valve, which is disposed between the pressure-reducing passage and the first passage, that controls the flow of the hydraulic fluid that is discharged from the channel of hydraulic fluid; a pressure-sustaining valve, which is disposed in each channel that extends from the first passage to the wheel cylinder and in each channel that extends from the second passage to the wheel cylinder, that controls supply of hydraulic fluid to the wheel cylinder; a pressure-reducing valve, placed between the pressure-reducing passage and each wheel cylinder; a pressure sensor that detects a hydraulic pressure of the second passage; and a response delay reduction section that reduces a response delay in changes in pressure in the second passage relative to changes in pressure in the first passage when the pressure change control of the wheel cylinder is performed by supplying hydraulic pressure using the pressure increase control valve, or by releasing hydraulic pressure using the pressure reduction control valve, wherein the response delay reduction section includes a pressure-increase response-delay section that temporarily limits inflow of the hydraulic fluid into the wheel cylinder that communicates with the first passage when the pressure increase control valve increases pressure to the channel of hydraulic fluid, and a pressure-reduction response-delay reducing section that opens, for a predetermined time, the pressure reducing valve assigned to the wheel cylinder that communicates with the second passage, when the pressure reduction control valve is controlled to reduce pressure in the channel of hydraulic fluid based on the hydraulic pressure of the second passage.