Study on Opening and Closing Motion Law of Common Rail Injector Needle Valve

The motion of common rail injector needle valve and the hydraulic process of fuel control circuit are studied by using simulation method. The simulation model is verified by comparing the injection rate curve. The results demonstrate that the lifting of the injector ball valve changes the fuel flow in the control chamber, leading to two different speed stages as the needle valve is opened. The seating of ball valve changes the clearance between the ball valve and the valve seat, and the needle valve closing motion curve slope remains unchanged. The increase of rail pressure affects the needle valve motion speed at the rapid opening stage. When the rail pressure reaches a certain valve, it no longer affects the motion characteristics of the needle valve. The change of fuel inlet hole diameter affects the needle valve rapid opening and closing movement. The change of fuel outlet hole diameter mainly affects the closing movement of needle valve.