Fluid injector having a novel inlet valve arrangement

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 piston chamber via an inlet orifice in an end face of the piston chamber, the piston chamber end face facing an opposed piston face of the piston;
• the one-way inlet valve comprises a sealing element located in the pumping chamber which is aligned with the inlet orifice and which can engage the piston chamber end face spanning the inlet orifice to seal the inlet orifice;
• and
• the piston can abut the sealing element to force the sealing element into sealing engagement with the piston chamber end face, with the sealing element clamped between the piston and the piston chamber end face.

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 via an inlet orifice in an end face of the piston chamber, the piston chamber end face facing an opposed piston face of the piston;
• the one-way inlet valve comprises a sealing element located in the pumping chamber which is aligned with the inlet orifice and which can engage the piston chamber end face spanning the inlet orifice to seal the inlet orifice;
• and
• the piston face is provided with a recess aligned with the sealing element which allows fluid to flow around the sealing element.

A positive displacement pump which 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 annular 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 on to the pumping chamber via an outlet orifice in the piston chamber end face spaced apart from the annular inlet orifice;
• and
• the one-way inlet valve comprises an annular sealing element which is aligned with the annular inlet orifice and which can engage the piston end face spanning the annular inlet orifice to seal the annular inlet orifice.

A positive displacement pump which 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 piston chamber via an inlet orifice in an end face of the piston chamber, the piston chamber end face facing an opposed piston face of the piston;
• the one-way inlet valve comprises a sealing element located in the pumping chamber which is aligned with the inlet orifice and which can engage the piston chamber end face spanning the inlet orifice to seal the inlet orifice;
• and
• the piston can abut the sealing element to force the sealing element into sealing engagement with the piston chamber end face, with the sealing element clamped between the piston and the piston chamber end face.

A positive displacement pump which 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 via an inlet orifice in an end face of the piston chamber, the piston chamber end face facing an opposed piston face of the piston;
• the one-way inlet valve comprises a sealing element located in the pumping chamber which is aligned with the inlet orifice and which can engage the piston chamber end face spanning the inlet orifice to seal the inlet orifice;
• and
• the piston face is provided with a recess aligned with the sealing element which allows fluid to flow around the sealing element.