| 摘要 |
1,196,901. Reciprocating pumps and motors. NATIONAL RESEARCH DEVELOPMENT CORP. July 25, 1966 [July 31, 1965], No.32862/65. Heading F1A. A cam track for a linear or radial ball piston hydraulic pump or motor is profiled so that each half lobe produces a piston stroke comprising a period of constant acceleration, a period of constant velocity and a period of constant deceleration, the west of each lobe being shaped to give a smooth transition of ball velocity at each piston innner dead centre position from the period of deceleration to the period of acceleration, formulae being given for the derivation of the crest shape. The lobe is also grooved to receive the ball pistons, the depth of the groove increasing at the crests of the cam track. The arrangement of the pump or motor is such that each period of acceleration or deceleration of one ball is complemented by a period of deceleration or acceleration, respectively, of another ball. The cam track may also be shaped to provide a dwell period at each inner dead centre of the ball pistons. |
