CHECK VALVE

摘要

A cartridge type check valve which may be either pilot operated or of the free flow type. The pilot operated type includes in combination a generally cylindrically-shaped housing having first and second end portions and having internal wall means defining an opening extending axially therethrough. A valve seat is formed on the internal wall means and a valve member is movable into and out of engagement with the valve seat to selectively prohibit and permit fluid flow through the axially extending opening at the valve seat. A fluid port is provided in the first end portion of the housing and serves to provide for fluid entrance into the axially extending opening. A control piston is positioned in the second end portion of the housing and is movable between first and second positions as is a valve stem, which is connected to the valve member and extends axially to a position adjacent the control piston and is adapted to be engaged and moved by the control piston. A valve guide is positioned in an intermediate portion of the housing and has a periphery located adjacent the internal wall means of the housing and this valve guide and the control piston define a fluid chamber therebetween. A stop shoulder is provided on the internal wall means and is engageable with the valve guide to limit movement of the valve guide in the direction of the valve seat. A central opening is provided in the valve guide which serves to slidably accommodate the valve stem and a fluid opening is provided in the valve guide for providing fluid communication between the fluid chamber and the axial opening at the first end portion of the housing. A spring member acts between the valve member and the valve guide tending to move the valve member into engagement with the valve seat and the valve guide into engagement with the stop shoulder. The free flow type also includes this structure with the exception of the control piston which is omitted and the fluid opening in the valve guide is enlarged. Another fluid port may be provided at the previous location of the control piston to provide for the entrance of additional fluid into the housing or it may completely replace the previously mentioned fluid port.