VALVE WITH A PRESSURIZED HYDRAULIC TRANSMISSION DEVICE AND A METHOD OF OPERATING SAME

摘要

A valve is disclosed with a hydraulic transmission device that is fluidly isolated from the process fluid. The pressure of the process fluid is employed to pressurize the hydraulic fluid. In a preferred embodiment, the valve is a common rail directly actuated fuel injection valve with a hydraulic transmission device that is fluidly isolated from the fuel so that the hydraulic fluid can be different from the fuel. This arrangement is particularly suitable for valves that inject a gaseous fuel, but can also be beneficial for use with liquid fuels. According to the method, the hydraulic fluid is pressurizable by the fuel pressure to reduce differential pressures and leakage, in addition to assisting with operation of the hydraulic transmission device. The method further comprises detecting the position of the valve needle for more accurate control of rate of fuel or process fluid flow through the valve.