Interest in the control of variable fluid power pumps/motors has increased in recent years. The actuators used are inefficient and expensive and this reduces the variable units’ usability. This paper introduces displacement control of pumps/motors by means of a rotating valve plate. By changing the angle of the valve plate, the effective use of the stroke is changed. The rotating valve plate is experimentally verified by a modified in-line pump. In the prototype, the valve plate is controlled with a worm gear connected to an electric motor. The results show potential for this kind of displacement control. However, the rotating valve plate creates pressure pulsations at part-displacement due to the commutation being performed at high piston speeds. If the piston speed and hence the flow from each piston is low, the pressure pulsation is acceptable.
Keywords: Fluid power pump/motor, displacement actuator