Spring actuated fuel pump for fuel injection systems

Claim 1

A piston-type pump adapted to supply fluid on demand under substantially constant pressure, comprising in combination: a pump housing including a powered rotatable drive shaft means located along the central axis of the housing, said drive shaft means having an offset portion intermediate the ends thereof; at least one piston bore located in said housing transverse to said central axis and extending radially therefrom; a pumping piston assembly including a reciprocally movable piston located in said bore and having an open end portion, a face portion, a generally hollow inner portion, and a generally cylindrical side portion, said face portion being adapted to cooperate with said offset portion of said drive shaft means so that said piston is moved thereby away from said central axis of said housing during a suction stroke of operation, a freely movable circular disc check valve member mounted in said hollow inner portion being adapted to travel a predetermined distance axially therein between an open and a closed position, a generally hollow cylindrical valve seat fitted into said open end portion of said piston and having a distal end projecting inwardly of said inner portion, said distal end being adapted to restrain the travel of said disc check valve member in one direction and defining said closed position thereby, said piston additionally having a shoulder located in said hollow inner portion opposing said distal end of said valve seat and being adapted to restrain the travel of said disc check valve member in an opposite direction and defining said open position thereby, at least one opening in said side portion, said opening having a dimension axially along said side portion at least equal to the travel of said disc check valve member and in registration therewith, whereby fluid passes through said generally hollow valve seat and around said disc check valve member into said hollow inner portion when said disc check valve member is in said open position but passes only through said at least one opening out of said generally hollow inner portion when said disc check valve member is in its closed position seated against said cylindrical valve seat during a pumping stroke of operation; a pumping spring located in said bore on the opposite side of said piston assembly from said drive shaft means and having one end thereof in contact with the proximal end of said cylindrical valve seat and being operable to effect said pumping stroke; means located in said bore adjacent the opposite end of said pumping spring for providing a rigid base for said pumping spring and additionally closing one end of said bore; fluid input means coupled to said bore in the region of the location of said pumping spring for delivering fluid to said piston assembly; and fluid output means including an output port extending across said bore in the region of the location of said piston side portion and adapted to be in registry with said at least one opening, said drive shaft means being operable to compress and cock said pumping spring whereupon fluid in said bore moves said freely movable disc check valve member against said shoulder and flows into said hollow inner portion, said pumping spring subsequently effecting a relatively short movement of said piston towards said central axis of said housing on output demand whereupon the fluid in said hollow inner portion urges said disc check valve against said valve seat which then forces the fluid captured in said hollow inner portion of said piston into said output port.