To solve the problem with automotive brakes or the like that the accuracy of control becomes unsatisfactory in a low pressure range if hydraulic control, which is required in a wide pressure range from low to high pressure, is effected by one control valve having a wide control range.
Two solenoid-driven proportional pressure control valves are placed between a hydraulic pressure source and load. The control valve 10L used is for low pressure while the control valve 10H is for high pressure. The pressure reducing port 14 of the control valve 10H is connected to the load port 13 of the control valve 10L and the two control valves are either used alternately or driven at the same time according to a hydraulic pressure area to control load hydraulic pressure.
HIGASHIMURA HIDEAKI
HASHIDA KOICHI
YAMADA SHINJI
Next Patent: BRAKE FLUID PRESSURE CONTROL DEVICE FOR VEHICLE