Patent ID: 8052401
Filing Date: 2011-11-08
Classification: F01B

Abstract:
1. A hydraulic apparatus comprising: a piston-cylinder housing having a central axis; a plurality of radially-oriented piston-cylinder assemblies each including a cylinder and a piston movable within the cylinder, the piston separating radially inner and outer chambers within the cylinder, wherein each cylinder is mounted to the housing for pivotal movement; wherein each piston has a piston rod extending through the radially inner chamber and a radially inner end of the respective cylinder, and wherein the radially inner ends of the piston rods are connected to a rotatably mounted eccentric to which a drive shaft is connected; and valving and associated flow passages for individually controlling the flow of hydraulic fluid to and from the radially inner and outer chambers of each piston-cylinder assembly; wherein the valving and flow passages include a plurality of valves movable radially in a valve housing, wherein the valves are moved in between open and closed positions in sequence with rotational motion of the eccentric; wherein the valving and associated flow passages include, for each of the valves, a pair of ports in the valve housing, one of which is in fluid communication with the inner chamber of one of the cylinders, and the other of which is in fluid communication with the outer chamber of the one of the cylinders, wherein 1) when each valve is in a first position a fluid inlet of the valve housing is in fluid communication with the inner chamber and a fluid outlet of the valve housing is in fluid communication with the outer chamber, and 2) when each valve is in a second position the fluid outlet of the valve housing is fluid communication with the inner chamber and the fluid inlet of the valve housing is in fluid communication with the outer chamber; wherein each of the valves includes a valve spool in a circumferential bore; wherein the valve housing has three annular passages in communication with the circumferential valve bores, with the annular passages including a middle passage between the other two passages; and wherein the middle passage is in communication with one of the fluid inlet or the fluid outlet, and the other two passages are in communication with the other of the fluid inlet or the fluid outlet.