Patent ID: 7134846

Claim:
A high pressure radial piston fuel pump comprising: an hydraulic head defining a central cavity for receiving a rotatable drive shaft longitudinally disposed along a drive axis passing through the cavity; a cylindrical drive member rigidly carried by and offset from the drive shaft for eccentric rotation in the cavity about the drive axis as the drive shaft rotates; a substantially cylindrical piston actuation ring annularly mounted around the drive member; bearing means between the drive member and the actuation ring, whereby the actuating ring is supported for freely rotating about the drive member; at least two piston bores extending in the housing to the cavity, each piston bore having a centerline that intersects the actuation ring but is offset (x) from the drive axis as viewed along the drive axis; a piston situated respectively in each piston bore for free reciprocation therein, said piston having an actuated end in the cavity and a pumping end remote from the cavity, wherein the pumping end cooperates with the piston bore to define a pumping chamber; a piston shoe rigidly extending from the actuated end of each piston, and having an actuation surface for maintaining contact with the actuation ring during rotation of the drive shaft; means for biasing each piston toward the cavity; a feed fuel valve train for delivering charging fuel through an inlet passage in the head at a feed pressure to the pumping chamber; a high pressure valve train for delivering pumped fuel to a discharge passage in the head at a high pressure from the pumping chamber; whereby during one complete rotation of the drive shaft, each pumping chamber undergoes a charging phase wherein the associated piston is retracted toward the cavity by the means for biasing, thereby increasing the volume of the pumping chamber to accommodate an inlet quantity of fuel from the inlet valve train, and a discharging phase wherein said associated piston is actuated away from the cavity by the actuation ring, thereby decreasing the volume of the pumping chamber and pressurizing the quantity of fuel for discharge through said discharge valve train; wherein the hydraulic head has a shaft mounting bore coaxial with the drive shaft axis, for receiving one end of the drive shaft, and bearing means for rotationally supporting said one end of the drive shaft; a removable mounting plate is attached to the hydraulic head, said mounting plate having a shaft mounting throughbore for receiving the other end of the drive shaft while exposing said other end for engagement with a source of rotational power, and bearing means for rotationally supporting said other end of the drive shaft; and the actuation ring has an outer surface that is crowned, having a curvature that rises and falls in the direction of the drive shaft axis.