Axial piston pump apparatus with an improved drive mechanism

Abstract

An axial piston pump apparatus includes a rotary cylinder barrel with plural cylinder bores in each of which a slidable piston is arranged. Each piston is rotatably held at one end with a piston support synchronously rotatable with the cylinder barrel. The piston support rotates in a plane inclined to the cylinder barrel, while each piston reciprocally moves in the corresponding cylinder bore to perform suction/discharging of a fluid. Two of the pistons come into surface contact with the corresponding cylinder bores; and the end of these pistons are held respectively in the piston support for radial movement to serve as drive pins for transmitting torque between the cylinder barrel and the piston support. During operation of the pump apparatus, the one end of each drive piston radially moves in accordance with rotation of the piston support, thereby preventing the drive pistons from inclining to the corresponding cylinder bores and appropriately maintaining surface contact between them. Thus, the two of the pistons serve as drive pins. This obviates the necessity of any separate drive mechanism and hence enables the reduction in size of the pump. Moreover, the drive pistons are kept is surface contact with the cylinder bores without impinging thereon thereby reducing noise and vibration of the pump apparatus.