Dynamic Pressure Simulation of an External Gear Pump With Relief Chamber Using a Morphological Approach

During the working cycle of an external gear pump, hydraulic oil trapped between the pair of meshing gear and pinon teeth may exert high-pressure pulses due to periodic volumetric compression and expansion of the trapped volume. The pressure pulses cause excessive alternating radial loads on the gear shafts, partially responsible for the noise and vibration in the unit. To reduce the trapped pressure pulsation, a relief chamber that connected to the trapped volume to absorb the pressure pulsation is designed in place of the traditional relief grooves to avoid the reconciliation between cross port leakage and pressure pulsation reduction. A new lumped parameter model compatible 2D morphological approach is proposed based on the mapping of gear profile function from real coordinate space to a binary-valued matrix in the integer coordinate space, reducing the control area calculation problem from polygon segmentation and numerical integration to pixel counting, relaxing the computational difficulty in design evaluations. Initial results show that the proposed method can trace and calculate the area of the trapped region, and the relief chamber is capable of effectively attenuating the peak magnitude of trapped pressure pulses by 95%.