Patent ID: 8439328

Claim:
A pressure control circuit for a fluid control valve, the pressure control circuit comprising the fluid control valve and a pressure controlling flow path for supplying and discharging a fluid for pressure control to the fluid control valve, wherein: the fluid control valve comprises a valve member having a drive shaft, the fluid control valve used in a gas flow path for supplying or discharging oxidation gas related gas or fuel gas related gas as reactant gas of a fuel cell, for blocking or connecting the flow in a gas flow path by a displacement of the drive shaft; the drive shaft is driven by both a first force acting due to a pressure difference between a first pressure chamber and a second pressure chamber that are separated from each other, and a second force acting in the same direction as the first force and acting due to a pressure difference between a third pressure chamber and a fourth pressure chamber that are separated from each other; in the fluid control valve, the first pressure chamber is the gas flow path in which the flows are blocked or connected by the valve member, while the second pressure chamber is open to the atmosphere; one of the third chamber and the fourth chamber receives pressure from gas which is the same and is supplied from the same supply side as the gas flowing in the gas flow path, while the other one of the third pressure chamber and the fourth pressure chamber is open to the atmosphere; the pressure controlling flow path comprises a main gas flow path which is a gas flow path in which flows are blocked or connected by a valve member, pressure controlling branch flow paths which are branched from the main gas flow path, and a compressor provided on an upstream side of the pressure controlling branch flow path and the main gas flow path; the pressure controlling branch flow paths include a branch flow path on the third pressure chamber side which is connected to the third pressure chamber, a branch flow path on the fourth pressure chamber side which is connected to the fourth pressure chamber, and a three-way solenoid valve provided at a branching portion between the branch flow path on the third pressure chamber side and the branch flow path on the fourth pressure chamber side of the pressure controlling branch flow paths; and the branch flow path on the third pressure chamber side and the branch flow path on the fourth pressure chamber side are selectively open to the atmosphere by different solenoid valves.