抄録
Oil-hydraulic pumps are positive displacement machines and prime components of fluid power systems, which transform energy between mechanical sources and pressurized oils. The reliability and efficiency of pump components are highly dependent on the tribological characteristics of the sliding parts, which perform bearing and sealing functions. Higher pressurization and increased compactness cause higher contact pressure and oil temperature, which can result in catastrophic damage of components and deterioration of the oils. Three representative hydraulic pumps-including a swash-plate axial piston pump, a pressure-balance vane pump, and an external gear pump-were tested under real operating conditions in terms of thermal effects. Discharge pressures up to 21 MPa and rotational speeds up to 50 rps were tested. Hydraulic oils with viscosity grades of 22, 32, and 46 were used at 30-50°C. The thermocouples were embedded in the cylinder-block, valve-plate, and swash-plate of the piston pump, in the cam-ring and side-plate of the vane pump, and in the side-plate of the gear pump. The platinum resistance thermometers were placed in the conduits close to the pump discharge ports. Temperatures of the sliding parts and working oils were measured simultaneously. Results indicated that for all pump tests, temperatures increased almost monotonically as discharge pressure increased. Temperatures at the sliding parts were much higher than temperatures of the oils at all pump outlets. With the piston pump, the temperatures at the location corresponding to the discharge port of the swash-plate and valve-plate were higher. In contrast, for the vane pump, the temperature at the location on the cam-ring close to the suction port was highest.
