Shoupeng Song

The internal curve hydraulic motor valve plate has a clearance self-compensation performance that can effectively improve the working efficiency of the valve plate. However, the dynamic characteristics of the valve plates require further investigation. This study considers the self-compensating ‘floating’ valve plate as the research object, proposes a dynamic characteristic analysis method for the internal curve hydraulic motor valve plate, and explores the changing rule of oil film thickness and surplus pressing force of the valve plate. The results showed that an increase in the inlet pressure and oil temperature led to an increase in the thickness of the oil film, and the amplitude of the oil film thickness was larger, whereas the rotational speed of the oil film thickness of the valve plate pair was not obvious. When the inlet pressure is lower than 8 MPa, and the oil temperature is in the range of 20–30 °C, the oil film is mainly subjected to the squeezing effect of the valve plate, and the displacement of the valve plate decreased with increasing rotational speed. The inlet pressure is the main factor affecting the displacement of the ‘floating’ valve plate, and when the inlet pressure reaches 8.7 MPa, the valve plate is in hydrostatic balance support. In addition, the surplus pressing force coefficient of the valve plate decreased with increasing inlet pressures. This study provides theoretical support for the design of variable pressing force valve plates for internal curve hydraulic motors by investigating the dynamic characteristics of “floating” valve plates.

Internal curve motors (ICMs) are used in construction and port machinery owing to their low speed and strong torque. The internal leakage of an ICM has a direct impact on its working performance; however, research on the internal leakage of ICMs is unclear. A method, based on the Computational Fluid Dynamics (CFD) transient simulation of an ICM, for obtaining the transient pressure in the plunger chamber and combining the mathematical model of internal leakage is calculated, and the internal leakage is proposed. We one-factor analyzed the internal leakage of the ICM and the effect of the valve pair and plunger pair leakage, and conducted multifactor analysis on the effect of the interaction between those two factors on the internal leakage of the ICM. The results show that the internal leakage mechanisms affecting the ICM were, in descending order of impact, the inlet pressure, oil temperature, and rotational speed, and a significant interaction existed between the inlet pressure and oil temperature, whereas the influence of rotational speed was not significant.