摘要 |
An hydraulic head 10 of the pump features two (or three) individual radial pumping pistons 26a,26b and associated pumping chambers 32, annularly spaced around a cavity 12 where a rotating eccentric drive member 18 and associated outer rolling actuation ring 20 are situated. Rolling interaction is provided between the ring 20 and the inner ends 28 of the pistons for intermittent actuation, and sliding interaction is provided between the ring 20 and the drive member 18. Inlet and outlet valve trains are also situated in the head, which is attachable to an application or customer specific mounting plate. Each piston has a piston bore with a centerline that intersects the actuation ring 20 but is offset (X) from the drive axis as viewed in cross section perpendicular to the drive axis. Additionally the piston bore centerlines are parallel to each other but offset (Y) from each other as viewed in longitudinal section along the drive axis. The outside surface of the ring 20 may be barrel shaped, to compensate for any misalignment of the pistons relative to the drive shaft due, for example, to either tolerance stack up or deflection. |