Since the vibration frequency was within the frequency range of valve noise, attention was first focussed on modifications of the by-pass valve to alleviate its coupling with any other possible sources in the piping system.
While the two sensitivity indexes of the natural frequency of servo valve, the damping ratio of servo valve, the system supply oil pressure, the internal leakage coefficient, the effective piston area of servo cylinder, the proportional gain, the force sensor gain and the viscous damping coefficient are large.
While the two sensitivity indexes of the natural frequency of servo valve, the damping ratio of servo valve, the system supply oil pressure, the internal leakage coefficient, the effective piston area of servo cylinder, the proportional gain, the force sensor gain and the viscous damping coefficient are large. .
Second, two strategies to equalise and optimise the workload (conduction ratio and switching frequency) of each valve are developed: 1) the circular queue schedule strategy ensures uniform workload of each valve and 2) the circular queue with random rotation schedule strategy can further decrease the switching frequency drastically by introducing randomness.
The analytical resonant frequency of the valve is up to 50 kHz and operates at high delta pressures (i.e. 0.14 MPa).
The experimental results show that the burst frequency of the valve with the same geometry design can range from 900 rpm to 1600 rpm.
With taking into account the influence of liquid added mass and added damping on the natural frequency of the valves and actuator, the design method of the cantilever valve was presented.
The effect of the system's physical parameters on the burst frequencies of the valve and the interaction between different valves were investigated both experimentally and theoretically.
Besides, the effects of chilled water temperature, cooling water temperature, pump frequency and opening of valve on COP and cooling power were analyzed respectively.
A limit-cycle generator is programmed into a microcontroller embedded with a DSP engine, which temporally keeps the switching frequency of the photo valve on one of resonant frequencies to pump up vibration power.
