Patent ID: 8813787

Claim:
A single-acting directional control valve comprising: a valve body having a supply port, an output port, and a discharge port; a valve chest formed inside the valve body so as to be in communication with the supply, output, and discharge ports; a valve rod accommodated in the valve chest so as to be able to slide in a direction of an axial line of the valve chest; a switching driver which drives the valve rod; and a return spring, wherein the valve chest includes a supply valve seat surrounding a channel between the supply port and the output port, and a discharge valve seat surrounding a channel between the output port and the discharge port, the supply valve seat and the discharge valve set being formed so as to face each other in the direction of the axial line, wherein the valve rod includes a round poppet valve provided between the supply valve seat and the discharge valve seat, and narrow portions continuous with right and left side surfaces of the poppet valve, respectively, wherein the right and left side surfaces of the poppet valve are orthogonal to the axial line, annular valve seats are formed on the right and left side surfaces of the poppet valve so as to contact and separate from the discharge valve seat and the supply valve seat, respectively, and the poppet valve is integrated with an annular protruding wall formed on at least a side surface of the poppet valve, the side surface being selected from the right and left side surfaces of the poppet valve so as to protrude in the direction of the axial line, and the side surface facing the discharge valve seat, and wherein the protruding wall has a circumference surface including a cylindrical surface having a uniform outer diameter and extending in parallel with the axial line, and an inclined surface which enables a base end of the cylindrical surface to be smoothly continuous with the side surface of the poppet valve, the inclined surface having a diameter that gradually increases toward the side surface of the poppet valve, and the cylindrical surface having a diameter smaller than a diameter of the poppet valve and larger than a diameter of the narrow portions of the valve rod.