Abstract: To study the high noise reason of hydraulic transformer in-depth, instantaneous flow rate characters are studied both in theory and through simulation analysis. Mathematic models are obtained by theoretical analysis considering different working situations and valve plate control angles. The instantaneous flow variation rules for each port in valve plate at varying working conditions are concluded by simulation analysis using the mathematic models. And these mathematic models are also optimized through the upper conclusions. Pulsation coefficient at every port is evaluated at different working situations. The results indicate that high pulsation coefficient is one of the main causes that bring about high noise. Experiment results also show that noise of the hydraulic transformer is much higher than the similar structured piston pump or motor. Analyzing results provide a high noise reason, which would be an important theoretical reference for further improving the hydraulic transformer.

Key words: Flow rate character, Hydraulic transformer, Instantaneous flow rate, Noise