Patent ID: 6443420
Filing Date: 2002-09-03
Classification: F16K

Abstract:
A solenoid valve having a valve housing with an inlet and an outlet, an annular valve seat formed in said valve housing between said inlet and said outlet, a solenoid with a movable core, a tubular seat bushing coupled to said core and having a tapered sealing edge for cooperation with said annular valve seat, said core having an end face remote from said annular valve seat and exposed to pressure at the inlet, and further comprising a pilot valve having a valve body including a portion defining a bore for connecting said inlet and outlet when the pilot valve is open, a pilot valve seat accommodated within said seat bushing and a sealing member coupled to said core and cooperating with said pilot valve seat, said seat bushing and said sealing member being movable relative to each other in an axial direction of said core, and said tapered sealing edge of said seat bushing making substantially line contact with said annular valve seat when said valve is closed, the surface area encompassed within the line contact less the area defined by said bore defining an effective surface having the same area as that of said end face of the core for balancing the forces due to pressure at opposite ends of said core, whereby said valve is normally biased into said closed position and said solenoid need overcome only the biasing force to open said valve.