Patent ID: 7232293
Filing Date: 2007-06-19
Classification: F04B

Abstract:
1. A manual hydraulic pump comprising: a housing having a closed end and an open end; a shaft supported rotatably by the housing and extending on a common axis through the closed end of the housing; a cylinder block supported rotatably in and by the housing; the cylinder block coupled to the shaft coaxially therewith to turn therewith; the cylinder block having cylinders formed therein at regular intervals around the common axis, the cylinders extending in parallel with the common axis, the cylinders each having an open end remote from the open end of the housing and a closed end adjacent to the open end of the housing; the cylinder block further having an end surface adjacent to the open end of the housing; the cylinder block further having oil passages each extending between the end surface and the closed end of one of the cylinders; pumping pistons each engaging axially slidably with one of the cylinders and capable of creating hydraulic pressure when the shaft turns; an end block closing the open end of the housing; the end block and the end surface of the cylinder block defining an end space therebetween; the end block having a pair of first cylindrical holes opening into the end space, the first cylindrical holes being opposite to each other diametrically of the common axis; the end block further having a pair of inlet/outlet ports each communicating with the outside of the pump and one of the first cylindrical holes; a distributing valve put in the end space and spring-biased into compressive contact with the end surface of the cylinder block; the distributing valve substantially taking the form of a disc and having a thickness smaller than the distance between the end block and the end surface of the cylinder block; the distributing valve having a pair of arcuate ports formed on the side thereof adjacent to the cylinder block, the arcuate ports being opposite to each other diametrically of the axis of the valve, the arcuate ports being capable of communicating selectively with the oil passages of the cylinder block when the cylinder block turns; the distributing valve further having a pair of second cylindrical holes formed on the other side thereof, the second cylindrical holes being opposite to each other diametrically of the axis of the valve, the second cylindrical holes each communicating with one of the arcuate ports; a pair of pressing pistons each including a large-diameter cylindrical part and a small-diameter cylindrical part that is coaxial with and smaller in diameter than the large-diameter cylindrical part, the large-diameter cylindrical part engaging axially slidably with one of the first cylindrical holes, the small-diameter cylindrical part engaging axially slidably with one of the second cylindrical holes; the pressing pistons each having an axial bore cut therethrough; first O-rings each interposed between the large-diameter cylindrical part of one of the pressing pistons and the end block; and second O-rings each interposed between the small-diameter cylindrical part of one of the pressing pistons and the distributing valve.