Patent ID: 8132593
Filing Date: 2012-03-13
Classification: F16K,Y10T

Abstract:
1. A pilot-operated three-port valve comprising: three ports including first, second, and third ports; two valve seats including first and second valve seats that are formed in a channel connecting these ports and that are concentric and opposite each other; a poppet-type valve member that is disposed between these valve seats and that operates so as to open one of the valve seats when the other is closed; a rod connected to this valve member; and a pilot operating portion that opens and closes the valve member using the rod by the action of pilot fluid pressure, wherein the ports are formed in a valve housing, the first valve seat and the second valve seat are respectively formed in a first valve seat block and a second valve seat block that are formed separately from the valve housing, and wherein these valve seat blocks are fitted to the housing, wherein the first valve seat and the second valve seat are respectively formed out of ring shaped parts protruding from the first valve seat block and the second valve seat block and have flat seat surfaces in ends of the ring shaped parts, wherein the valve member is short-cylindrical in shape with a uniform diameter, the valve member integrally having a first seal surface and a second seal surface that come into and out of contact with the seat surfaces of both the valve seats at both end surfaces in the axial direction of the valve member, the valve member has a rod fitting hole extending along the axis of the valve member from the side of the first seal surface, wherein the rod fitting hole does not penetrate to the side of the second seal surface, the end portion of the rod being inserted into the rod fitting hole, an O-ring being provided between the rod fitting hole and the end portion of the rod inserted into the rod fitting hole, whereby the valve member is airtightly and inclinably attached to an end of the rod coaxially and so as to have a degree of freedom of inclination from the axis of the rod, and wherein the rod is connected to a piston disposed in a piston chamber of the pilot operating portion, the rod passing through a bearing block for separating the piston chamber and the channel slidably and passing through a channel hole of the first valve seat, a rod end portion is connected to the valve member, a diameter of the rod end portion of the rod is smaller than a diameter of a rod base end portion passing through the bearing block, and a diameter of a rod middle portion passing through the channel hole of the first valve seat of the rod is smaller than the diameter of the rod end portion.