This paper deals with the system modeling and dynamic characteristics of an electro-pneumatic hybrid actuator. This system is composed of a pneumatic, an electric and a mechanical driving sub-system. The pneumatic driving system controls the pressure supporting the inertial mass, which means that the pressure corresponds to the gravitational force acting on it. The electric driving system with small capacity moves the inertial mass vertically by way of a ball screw as a mechanical driving sub-system. In the present study, in order to develop the electro-pneumatic hybrid actuator, the mathematical model of this system has been refined by comparing calculation data with the experimental results, especially through measuring precisely frictional force of the ball screw. Also, the power consumption as well as the dynamic characteristics have been investigated numerically when the inertial mass moves vertically upwards and downwards during one cycle. The method of predicting power consumption during one cycle will be useful to select a suitable driving motor in the design stage.

View full abstract

This study deals with a newly proposed electro-magnetic proportional actuator for hydraulic control valves, in which multi poles are arranged in a row. The force produced by this actuator is more than 2.5 times as large as that of conventional proportional electro-magnetic actuators of solenoid type. Performances of this actuator have been reported in previous papers. In this paper, influences of dimensions such as clearance between stator and armature, thickness of the armature and length of the top land of the armature are investigated experimentally. It becomes clear that the produced force increases with reduction in the clearance between stator and armature. Moreover, influences of the thickness of the armature are not so large as long as the length of the top land is smaller than 40% of the thickness of the armature. The results in this paper will be profitable for designing the actuator.

View full abstract

This paper is concerned with the experimental determination of an inherent pulsation power level generated by a hydraulic pump, using both the test method originally developed for the measurement of fluid pulsation power in a pipeline and the theoretically derived conversion equation for eliminating the influence of a hydraulic circuit. The suitability of the test procedure as a standard method for assessment of an inherent source pulsation power of a hydraulic pump was confirmed. First, it was found that the pulsation power in a pipeline can be measured using a pressure sensor unit called a “pulsation intensity probe” with the same measurement principle as the conventional sound intensity probe, with good repeatability and with sufficient accuracy for practical usage. Next, the standard test procedure for determining the inherent source pulsation power of a hydraulic pump, which is independent of a hydraulic circuit connected to the pump, from the measurements of the pulsation power in a reference pipe was proposed. Finally, it was verified from the experimental measurements and simulations that this proposed standard test method was very useful for both the absolute and relative assessments of source pulsation power level of a hydraulic pump.

View full abstract