| 摘要 |
<p>IMPROVEMENT IN HYDRAULIC PISTON AND CYLINDER MACHINES The machine comprises a plurality of pistons and cylinders, a ring of ports (P1 to P8) for alternatively supplying fluid into, and for allowing it to be discharged from each cylinder and a cam shown in chain dotted outline having a plurality of lobes to control the displacement of the pistons in a cylinder block with respect to the progression of the cylinder block along the direction of the cam or vice versa. Each of the pistons traverses each of the cam lobes during a full rotation of the machine to undergo a number of piston strokes equal to the number of lobes. Valve means (9) is adjustable to route working fluid discharged through at least one of the fluid discharge ports of the machine to the exhaust fluid outlet (E) of the machine during each full rotation of the machine via an isolated pressure zone (Z) of the machine in which the pressure of fluid is maintained by restrictions (54,55) at a pressure intermediate the supply (I) and exhaust (E) pressures of working fluid to and from the machine, thereby to reduce the capacity of the machine to receive and discharge working fluid, said isolated pressure zone (Z) being of constant volume and always including, for the time being, the cylinders of at least two pistons and cylinders of the machine.</p> |
