Patent ID: 7523763
Filing Date: 2009-04-28
Classification: F15B,F16K,Y10T

Abstract:
1. A three-port electromagnetic valve including a valve body having a poppet type valve member disposed therein and a drive mechanism for switching a flow path by driving the poppet type valve member, the valve body having a through hole through which first, second and third ports of the valve body are opened; which comprises: first and second retainers formed of synthetic resin which are cylindrically shaped and which are fitted to both end sides of the through hole, respectively, and which have center holes formed therein, convex ring-shaped valve seats positioned opposite each other across the second port of the valve body and which are disposed so as to be positioned, respectively, at opposite end walls of each of the retainers, wherein each of the retainers have communication openings formed therein for communicating with the first and third ports, located on opposite sides of the second port of the valve body, and with the center holes formed in the first and second retainers, respectively; wherein the poppet type valve member has a poppet seal portion and first and second slide portions which are disposed to form a stem wherein the poppet seal portion is disposed between the opposite convex ring-shaped valve seats and is positioned opposite the first and second retainers, and an O-ring shaped elastic sealing member positioned in said valve body, wherein the first and second slide portions are continuously slidably disposed in said valve body and are maintained therein via said O-ring-shaped elastic sealing member, respectively, said slide portions being positionable in the central holes of both the retainers at positions in closer proximity with both ends of the through hole than with the communication openings; the first and second retainers having reduced diameter portions formed by reducing a diameter portion of the inner peripheral wall of the retainers in proximity with each of the end portions of the sides of the valve seats, the valve seats being formed on end portions of reduced diameter portions of the first and second retainers, and wherein effective seat diameters of the valve seats are larger than inside diameters of said reduced diameter portions of the first and second retainers and are equal to inner surface diameters of the retainers of the first and second retainers with which the slide portions of the valve members come into sliding contact such that, when said poppet seal portion contacts said first and second valve seats and the center holes of the first and second retainers are closed by said poppet seal portion and by said elastic sealing member, fluid pressure forces inversely acting on the valve members in the closed center holes of said first and second retainers are equalized.