초록 ▼

A solenoid-operated control valve has a main orifice and a valve member for controlling fluid flow therethrough. A leakage orifice extends through the valve member. A check valve seals the leakage orifice when the main orifice is blocked and moves to open the leakage orifice before the main orifice

A solenoid-operated control valve has a main orifice and a valve member for controlling fluid flow therethrough. A leakage orifice extends through the valve member. A check valve seals the leakage orifice when the main orifice is blocked and moves to open the leakage orifice before the main orifice is opened.

대표청구항 ▼

In a servo-operated control valve having a housing defining an inlet and an outlet, a poppet movable in the housing to control fluid communication between the inlet and the outlet, the poppet having a first passage extending therethrough and communicating with the outlet and a first valve seat surro

In a servo-operated control valve having a housing defining an inlet and an outlet, a poppet movable in the housing to control fluid communication between the inlet and the outlet, the poppet having a first passage extending therethrough and communicating with the outlet and a first valve seat surrounding an end of the first passage, the control valve also having a hollow main valve member movable in the housing and cooperating with the first valve seat to control fluid communication through the first passage, the valve member having a second passage extending therethrough, the control valve also having a hollow armature member movable in response to operation of the servo to move the valve member, and a pressure-balancing pin movably received by the armature for balancing hydraulic forces acting upon the armature and valve members, the first and second passages forming a flow path to the outlet for fluid which leaks past the pressure-balancing pin, the improvement wherein: a check valve seat surrounds one of the second passage and is spaced apart from the first valve seat; and a check valve member is located between the armature and the valve member and is movable in response to a pressure differential between the inlet and the outlet to a first position sealingly engaging the check valve seat to block leakage flow from the inlet to the first and second passages and to a second position spaced apart from the check valve seat to permit leakage flow from the inlet to the first and second passages.