Patent ID: 8348351

Claim:
A brake control device comprising: a hydraulic pressure source comprising a pump for pumping working fluid from a reservoir and an accumulator for accumulating the working fluid pumped by the pump; a pressure governing valve for regulating and outputting hydraulic pressure supplied from the accumulator corresponding to a stroke amount of a brake operating member; a plurality of wheel cylinders operated by the output hydraulic pressure outputted from the pressure governing valve; an electromagnetic valve that is normally closed and is provided on a hydraulic pressure passage and directly communicated with a low pressure chamber of the pressure governing valve, thereby to allow the reservoir to communicate with a hydraulic pressure passage when the electromagnetic valve is opened, allowing a hydraulic pressure output side of the pressure governing valve to communicate with the wheel cylinders; a first hydraulic pressure sensor for detecting a value of the hydraulic pressure supplied from the accumulator into the pressure governing valve; an output hydraulic pressure sensor for detecting a value of the output hydraulic pressure outputted from a hydraulic pressure output side of the pressure governing valve into the wheel cylinders; a stroke amount detecting part for detecting a stroke amount of the brake operating member; and a control unit for controlling the electromagnetic valve to open and close, depending on information detected from the first hydraulic pressure sensor, the output hydraulic pressure sensor and the stroke amount detecting part, wherein the control unit selectively controls the electromagnetic valve to open so as to output a part of the output hydraulic pressure outputted from the hydraulic pressure input side of the pressure governing valve via the hydraulic pressure passage on which the electromagnetic valve is provided and the low pressure chamber of the pressure governing valve into the reservoir when determining that a trouble has occurred on the pressure governing valve, wherein the control unit determines the trouble on the pressure governing valve if determining that: the hydraulic pressure within a defined range is outputted from the accumulator to the hydraulic pressure input side of the pressure governing valve, based on information on the detected value inputted from the first hydraulic pressure sensor; a value of the output hydraulic pressure outputted from the hydraulic pressure output side of the pressure governing valve at a time of a braking operation by the brake operating member is higher than a reference output pressure depending on information on the stroke amount of the braking operation inputted from the stroke amount detecting part, based on information on the detected value inputted from the output hydraulic pressure sensor; and a difference between the value of the output hydraulic pressure and the reference output pressure is greater than a predetermined value; thereby to generate a master cylinder pressure in accordance with the reference output pressure.