Patent ID: 7410223

Claim:
A hydraulic brake device comprising a hydraulic pressure source for generating and outputting a predetermined hydraulic pressure, the hydraulic pressure source including a power-driven pump for producing hydraulic pressure and a pressure accumulator for accumulating hydraulic pressure produced by the pump, a pressure adjusting valve including a pressure adjusting mechanism for adjusting the output hydraulic pressure of said hydraulic pressure source to a value corresponding to a brake operating amount of a brake operating member, and wheel cylinders actuated by the output hydraulic pressure of said pressure adjusting valve for imparting braking force to wheels of a vehicle, further comprising a hydraulic passage leading from said pressure adjusting valve to said wheel cylinders, a hydraulic pressure supply passage for supplying hydraulic pressure from said hydraulic pressure source to said hydraulic passage at a junction therewith, the hydraulic pressure supply passage by-passing the pressure adjusting mechanism of the pressure adjusting valve, a first proportional solenoid valve provided in said hydraulic pressure supply passage for reducing the output hydraulic pressure of said hydraulic pressure source before being supplied to said hydraulic passage, a second proportional solenoid valve provided in said hydraulic passage at a location between said pressure adjusting valve and said junction and operable for reducing the output hydraulic pressure supplied from said hydraulic pressure supply passage, a check valve provided in parallel to said second proportional solenoid valve for allowing fluid flow from said pressure adjusting valve to said junction while bypassing said second proportional solenoid valve, an atmospheric reservoir communicating with said hydraulic passage through said pressure adjusting valve during automatic brake control, and a controller for controlling said first and second proportional solenoid valves, each of said first and second proportional solenoid valves being of the type in which a differential pressure between upstream hydraulic pressure and downstream hydraulic pressure thereof is controllable to a value corresponding to a control current applied thereto, wherein said controller controls said first proportional solenoid valve during automatic brake control to increase the hydraulic pressure in the wheel cylinders and controls said second proportional solenoid valve during automatic brake control to decrease the hydraulic pressure in the wheel cylinders by communicating the wheel cylinders with said atmospheric reservoir through said second proportional solenoid valve and said pressure adjusting valve, and wherein when the output hydraulic pressure of said pressure adjusting valve exceeds the hydraulic pressure in the wheel cylinders in response to operation of the brake operating member during the automatic brake control, the output hydraulic pressure of said pressure adjusting valve is supplied into the wheel cylinders through the check valve.