Patent ID: 7665579

Claim:
A flow control valve, comprising: a pressure compensating valve configured to enlarge an opening area of a variable orifice between a load pressure line and a compensating pressure line when a pressure of working fluid in said compensating pressure line is smaller than a first set pressure, and narrow said opening area of said variable orifice when said pressure of said working fluid in said compensating pressure line is larger than said first set pressure; and a first switching valve configured to switch between a meter-out operation and a neutral operation by an external operation. wherein said working fluid in said compensating pressure line is drained in said meter-out operation, and neither said working fluid is supplied to said load pressure line nor said working fluid in said compensating pressure line is drained in said neutral operation; wherein said load pressure line guides said working fluid to be supplied to an actuator; and said pressure compensating valve varies the opening area of said variable orifice when said first switching valve is in the neutral operation, the flow control valve further comprising: a relief valve configured to drain said working fluid in said compensating pressure line when said pressure of said working fluid in said compensating pressure line is larger than a second set pressure, and configured not to drain said working fluid in said compensating pressure line when said pressure of said working fluid in said compensating pressure line is smaller than said second set pressure, wherein said first switching valve switches among a meter-in operation, said meter-out operation, and said neutral operation by an external operation, wherein said working fluid is supplied to said load pressure line in said meter-in operation for operating said actuator, wherein said relief valve is not connected to said compensating pressure line when said first switching valve is in said meter-in operation.