Direct Type Pressure And Flow Rate Multiple Control Valve

The hydraulic systems of many practice projects are always required to control speed and moment of output in different phases. The hydraulic system of injection molding machine is the representative example, it need to control cylinder speed and hold pressure, so it indeed to use pressure and flow rate multiple valve.The conventional device for pressure and flow rate multiple control is always a combination of a relief valve and a compensated flow rate valve, the structure of the valve is complicated and the cost is much higher. In this paper, a special hydraulic bridge was developed to undertake pressure control in a pressure compensated flow rate valve and thus a new type of P-Q control valve is constructed. The pressure control in this P-Q valve is a hydraulic bridge formed by the serial connection between a metering orifice and a drain orifice. The control valve is indeed greatly simplified and can be maintained easily. The contents of thesis are as follows:...