Effect of piston-slipper assembly mass difference on the cylinder block tilt in a high-speed electro-hydrostatic actuator pump of aircraft

When manufacturing axial piston pumps, mass difference of piston-slipper assembly is inevitable because of manufacturing precision limits. Small mass difference may not cause problems when the pump operates at low speeds, while it cannot be ignored at high speeds. One problem related to high speed is the cylinder block tilt resulting from the inertial effect of piston-slipper assembly. Recently, the speed of electro-hydrostatic actuator (EHA) pump in aircraft can reach more than 10,000 rpm. Therefore, mass difference of pistonslipper assembly should be taken into account in future EHA pump design. The main purpose of this paper is to investigate the effect of the mass difference of piston-slipper assembly on the cylinder block tilt in a high-speed EHA pump. A detailed set of relevant equations is developed to establish the relationship between the mass difference of piston-slipper assembly and cylinder block tilting moment. It is found that a tighter control over the mass difference of piston-slipper assembly should be guaranteed when it comes to high-speed EHA pumps.