Chemical injection valve

Claim 1

A valve for use in injecting fluid from an annulus about a tubing string into the bore of the tubing string, wherein the tubing string includes a mandrel having means to one side of the bore for receiving the valve, said valve comprising an elongate single wall housing which is essentially tubular from end to end having, inlet means to interior of the housing at one end thereof, outlet means from the interior of the housing at the other end thereof, and means cooperable with the mandrel, where so received, to open the inlet means to the annulus and the outlet means to the bore of the tubing, a sleeve fixedly mounted within the housing near its one end, means sealing between the sleeve and inner surface of the housing, ports in the sleeve having outer ends connecting with a substantially unobstructed annular space between the sleeve and the inner surface of the housing which opens to an open chamber within the inner surface of the housing leading to the outlet means, an impervious metering member fitting snugly within the sleeve for reciprocation between positions opening and closing the inner end of the ports, and the one end of the housing being closed to form a variable volume chamber with the metering member, the inlet means comprising ports in the housing and the sleeve for connecting the annulus with the chamber a coil spring within the open chamber and fitting relatively closely within the inner surface of the housing for urging said metering member toward closing position.