Patent ID: 8757131
Filing Date: 2014-06-24
Classification: F02M,F04B

Abstract:
1. A fluid injector which functions as a positive displacement pump and comprises: a housing in which a piston chamber is formed; a piston which reciprocates in the piston chamber to define therewith a variable volume fluid pumping chamber; a one-way inlet valve which allows flow of fluid into the pumping chamber from a fluid inlet; a one-way outlet valve which allows flow of fluid out of the pumping chamber to a fluid outlet; wherein in operation of the injector the piston cyclically moves to increase volume of the pumping chamber and draw fluid into the pumping chamber via the one-way inlet valve and then the piston moves to decrease volume of the pumping chamber and expel fluid from the pumping chamber via the one-way outlet valve; characterised in that: the fluid inlet comprises an inlet passage through the housing which opens on to the pumping chamber as an inlet orifice provided in an end face of the piston chamber, the piston chamber end face facing an opposed piston face of the piston; the fluid outlet comprises an outlet passage through the housing which opens onto the pumping chamber via an outlet orifice in the piston chamber end face spaced apart from the inlet orifice; and the one-way inlet valve comprises a sealing element which is aligned with the inlet orifice and which can engage the piston end face spanning the inlet orifice to seal the inlet orifice.