Electromagnetic valve unit

Claim 1

An electromagnetic valve unit including a flow control valve assembly or controlling the flow of fluid passing therethrough and operatively associated with an electromagnetic motor assembly for actuating said valve assembly in response to an electric current applied thereto from an electric power source, said motor assembly comprising: a cylindrical housing of magnetic material provided at opposite ends thereof with first and second fitting faces; a solenoid coil concentrically assembled within said housing and connected to said electric power source; a stationary core of magnetic material fixed to said first fitting face of said housing and surrounded by said solenoid coil; an annular yoke member of magnetic material fixed to said second fitting face of said housing; a movable core of magnetic material arranged to be axially moved between said stationary core and said yoke member and being operatively connected to said flow control valve assembly, said stationary core and said movable core have confronting ends; resilient means for biasing said movable core toward said yoke member; one of said confronting ends being formed therein with an annular recess of a V-shaped cross-section forming a cylindrical inner surface and a conical outer surface convergent toward the other end, and the other end further comprising an annular projection corresponding in cross-section with the cross-section of said annular recess and forming a cylindrical outer surface and a conical inner surface respectively disposed in a parallel relationship with said cylindrical inner surface and with said conical outer surface of said one end; wherein said cylindrical inner surface is arranged to increase an annular area of said cylindrical outer surface overlapped therewith in accordance with axial displacement of said movable core toward said stationary core, and wherein the inner periphery of said yoke member is further arranged to increase an annular area of the outer periphery of the other end of said movable core overlapped therewith in accordance with the axial displacement of said movable core toward said stationary core.