Stop valve

Claim 1

In a stop valve including a main body defining a fluid passage and a valve chamber, a spindle having one end inserted into said valve chamber, a valve seat positioned in said fluid passage and a valve body positioned within said valve chamber and confronting said valve seat, the opening degree of said valve body relative to said valve seat being controlled by rotation of said spindle about its axis, the improvement comprising: (a) said spindle being coupled to said valve body and being freely rotatable along a circumferential direction with respect to said valve body, wherein said spindle includes a threaded portion formed at a longitudinal center portion thereof, a flange adapted to confront with an inner surface of a packing holder, a small diameter portion positioned within said valve chamber and a disc portion provided at the end of said spindle, said threaded portion being engaged with a matching threaded portion of a cap member positioned above said valve body and surrounding said spindle, and positioned above said packing, said disc portion being rotatably coupled to said valve body; (b) a rotation preventive means disposed between said valve body and said valve chamber to prevent rotation of said valve body relative to said valve chamber, wherein said rotation preventive means comprises protrusions radially inwardly projecting from an inner surface of said valve chamber and extending along the axial direction thereof, and corresponding recesses formed in an outer peripheral surface of said valve body to engage said protrusions; and (c) a packing interposed between said valve body and said valve chamber, wherein said packing is disposed between an annular packing receiver and a cylindrical packing holder, each disposed between said valve body and said valve chamber, confronting surfaces of said receiver and said holder being formed with a V-shaped projection and a V-shaped recess respectively to interpose said packing, wherein when said valve body is in a fully opened position an axial space exist between said packing receiver and said valve body to prevent imparting any varying compressional forces between said V-shaped projection and said V-shaped recess.