Axial piston device

Abstract

An axial piston device may be operated as a pump and includes a self-centering rotary valve. The device includes a stationary housing encompassing a shaft and the rotary valve. The rotary valve and the shaft are coupled to each other. Upon rotation, the rotary valve self-centers as a result of elimination of moments and forces within the pump. The inventive pump is a piston device. The valve is within a valve bore, which is a part of a manifold. A shaft is within the manifold and the shaft is attached at its distal end to a planar surface of the rotary valve. The shaft has a first axis of rotation and the rotary valve has a second axis of rotation. During operation of the pump, the first axis is often times offset from the second axis. The pump operates via a swashplate with reciprocating pistons while the housing remains stationary.

What is claimed is: 
     
         1 . A piston device comprising: a stationary cylinder block, a shaft that is rotatable about its own axis within the stationary cylinder block, and the shaft comprising a plurality of passages configured to receive, direct and exhaust fluid, the shaft centrically and eccentrically rotatable during operation of the pump, and a swash plate coupled to the shaft, the swash plate having a first side coupled to a first plurality of pistons. 
     
     
         2 . The piston device as recited in  claim 1  wherein the swash plate is configured to tilt about an axis perpendicular to the axis of the shaft. 
     
     
         3 . The piston device as recited in  claim 2  further comprising a means for tilting the swash plate. 
     
     
         4 . The piston device as recited in  claim 1  wherein fluid pressure on the passages in the shaft balances at least one force and/or moment. 
     
     
         5 . The piston device as recited in  claim 1  further comprising a respective plurality of slipper shoes each connected to a piston, and the swash plate comprising at least one active surface for interacting with the slipper shoes. 
     
     
         6 . The piston device as recited in  claim 1  wherein fluid flow throughout the pump creates at least one of a force and a moment on the shaft and the plurality of passages are configured on the shaft such that at least one of the forces or the moments on the shaft are balanced. 
     
     
         7 . The piston device as recited in  claim 6  further comprising a second plurality of pistons, each plurality of pistons contained within the cylinder block and arcuately positioned coaxial with the shaft on opposite ends of the cylinder block. 
     
     
         8 . The piston device as recited in  claim 7  further comprising a first active surface and a second active surface, the first and second active surfaces are on opposing sides of the swash plate. 
     
     
         9 . A piston device comprising: a stationary cylinder block; a shaft extending through the stationary cylinder block and having a plurality of passages along a portion of the shaft; and a valve enclosed within the stationary cylinder block, the valve comprising the shaft integrally coupled to the valve. 
     
     
         10 . The piston device as recited in  claim 9  further comprising a first plurality of pistons and a second plurality of pistons, each plurality of pistons arcuatley positioned coaxial with the shaft on opposite sides of the shaft. 
     
     
         11 . The piston device as recited in  claim 9  wherein the plurality of passages are configured to receive, direct and exhaust fluid flow throughout the pump. 
     
     
         12 . The piston device as recited in  claim 11  wherein the fluid flow throughout the pump creates at least one of a plurality of forces and a plurality of moments on the shaft and the plurality of passages are configured on the shaft such that the at least one of the plurality of forces and the plurality of moments is balanced. 
     
     
         13 . The piston device as recited in  claim 12  further comprising a plurality of slipper assemblies, each slipper assembly coupled to one piston of the plurality of pistons; and a swash plate coupled to the shaft and comprising at least one active surface for interacting with a respective slipper assembly. 
     
     
         14 . The piston device as recited in  claim 13  further comprising a first active surface and a second active surface, the first and second active surfaces are on opposing sides of the swash plate. 
     
     
         15 . A piston device comprising: a swash plate having a first side coupled to a first plurality of slipper shoes and a second side coupled to a second plurality of slipper shoes, the first side of the swash plate is generally parallel to the second side of the swash plate; and a first portion of the pump on the first side of the swash plate and a second portion of the pump on the second side of the swash plate, the first portion of the pump on the first side of the swash plate is substantially symmetric about the swash plate with the second portion of the pump. 
     
     
         16 . The piston device as recited in  claim 15  further comprising a shaft, the swash plate coupled to the shaft 
     
     
         17 . The piston device as recited in  claim 16  configured to be adjustable about an axis askew or perpendicular to an axis of the shaft. 
     
     
         18 . The piston device as recited in  claim 16  further comprising a means for balancing at least one of a plurality of forces and a plurality of moments acting on the shaft. 
     
     
         19 . The piston device as recited in  claim 17  further comprising a means for tilting the swash plate with respect to the shaft. 
     
     
         20 . The piston device as recited in  claim 16  further comprising a housing encasing the shaft, swash plate and slipper assemblies.