Poppet type change-over valve assembly

A poppet type change-over valve assembly for switching a direction of a fluid flow, comprising:

• a valve casing interiorly defining a generally cylindrical valve chamber and having valve guiding cavities at opposite ends thereof and a pair of opposingly disposed conical valve seats intermediate said cavities;
• said casing comprising a plurality of ports which communicate between said valve chamber and the casing exterior, including an input port disposed in said casing intermediate said casing's conical valve seats, a pair of output ports disposed in said casing on opposite sides of said casing's conical valve seats, and an exhaust port;
• a main valve body slidably received in said valve chamber and having sliding end portions in hermetical engagement with said valve guiding cavities of said valve chamber and a pair of opposingly disposed conical valve seats between said sliding end portions in face to face relation with said conical valve seats of said casing;
• an annular float valve loosely mounted around said main valve body between said opposingly disposed conical valve seats of said valve casing and of said main value body, said float valve having concentric outer and inner sealing edges for engagement with said conical valve seats of said valve casing and said main valve body;
• said conical valve seats of said main valve body and valve casing and said float valve being in a dimensional relationship dictated by an inequality .psi..degree. <
• 180.degree. - .theta..degree. <
• .phi..degree. (wherein .psi..degree. is a cone angle defining the conical valve seats of said main valve body, .phi..degree. is a cone angle defining the conical valve seats of said valve casing, and .theta..degree. is a cone angle containing two diagonally positioned sealing edges of said float valve);
• a valve biasing means for urging said main valve body to assume a first change-over position wherein said float valve is tightly held between one of said conical valve seats of said main body valve and said facing conical valve seat of said valve casing;
• a valve operating means provided at one end of said valve casing for shifting said valve body against the action of said valve biasing means into a second change-over position wherein said float valve is tightly held between the other of said conical valve seats of said main body valve and the other of said facing conical valve seats of said casing;
• a fluid exhaust passage, in communication with said exhaust port, extending axially through a portion of said main valve body and opening into said valve chamber through a radial port between said paired conical valve seats of said main valve body;
• said float valve thus being tightly held between said conical valve seats of said main valve body and said valve casing by the action of said main valve body and a fluid pressure prevailing in said valve chamber when said main valve body is shifted into either said first or second change-over position, establishing a tight seal around said main valve body thereby communicating a selected one of said output ports with said input port while draining another one of said output ports through said exhaust passage and said exhaust port in said valve casing.