Design of the swash-plate water hydraulic pump for environment-friendly actuator systems

This paper deals with a new development of a swash-plate hydraulic pump. It is particularly designed to aim its usage in applications where environmental impacts should be concerned. Thus, the pump is based on not mineral-based oil but simple tap water. The Electro-Hydraulic Actuator (EHA), a linear motion generator operated by an electric motor installed to the proposed pump, can be attractive and expandable to small-to-medium pressure applications. Water is clean and safe, and the size of EHA is relatively small. New design features of the pump including the no-shoe retainer, the inclination angle adjustment screw, the rotating cylinder block, and the simple assembly structure enabled EHA. The pump was designed to have its static pressure of 1.4 MPa and the volumetric flow rate of 10 × 10 3 mm 3 /s. To verify its performance, a series of experiments were constructed, and the maximum volumetric flow rate and pressure were found as 2935.87 mm 3 /s and 1.9 MPa, respectively. The maximum velocity of the actuator stroke was 9.35 mm/s. The EHA is controlled directly by the electric motor, and so a directional valve is not necessary. It is concluded the pump can be successfully used in small-to-medium pressure applications.