Abstract Claims Description Full Text

Abstract

A mass fluid flow controller has a valve which is controlled by a controller rod which is substantially pivotally mounted on a metallic diaphragm which stretches and unstretches with the movement of the rod. The actuation of the rod movement is by the expansion and contraction of an actuator wire which is heated for the expansion and allowed to cool for the contraction. The primary fluid flow path through the controller is straight. A sensor conduit, providing a parallel sensor fluid flow path, is connected in position using metallic sealer members which extend into openings to the primary fluid flow path and which are rounded along the direction through such openings. The pressure drop, along the primary fluid flow path, to create flow through the sensor conduit, is provided by a fluid flow restrictor having a core and having lengths of wire along the core which are squeezed between the core and a tapered fluid flow path wall in the vicinity of the sensor conduit input and output connections. A spherical or a conical shape may be used for the form of the core. A valve seat bushing is mounted in pipe structure providing the primary fluid flow path by applying a force against an end surface of the bushing, with movement of the bushing blocked, in order to deform the end surface, push the outer wall of the bushing against the inner wall of the pipe structure, and fix the bushing in the pipe structure.