Pressure-accumulating electronic fuel injector with variable fuel injection law

Abstract

It is an object of the present invention to provide a pressure-accumulating electronic fuel injector with a variable fuel injection law. The pressure-accumulating electronic fuel injector includes a pressurizing control valve portion, a three-stage piston assembly, a fuel injection control valve portion, a needle valve portion, a fuel injector body, and a pressure-accumulating chamber wall. The pressure-accumulating electronic fuel injector uses a two-stage electromagnetic valve structure to control the pressurizing area of the three-stage piston, can effectively realize different pressure ratios, and makes the fuel injection law more flexible. A through-type valve rod is used so as to increase the response speed of the fuel injection control valve. The pressure-accumulating chamber can reduce the pressure fluctuation caused by the fuel injection, contributes to the precise control of the fuel-injection quantity, and can especially significantly improve the control precision of a smalloil quantity. The pressure stabilizing effect of the pressure-accumulating chamber reduces the size of a common rail tube so as to prolong the service life of the common rail tube. A hydraulic compensation piston mechanism used by the pressure-accumulating electronic fuel injector supplements the fuel when the control chamber is depressurized, and has an effect of supplying fuel by two passages when the pressure is built, so that the fuel injection law has a characteristic of decreasing first and then increasing, and the fuel injection performance is improved.

Description

technical field [0001] The invention relates to a diesel engine, in particular to a diesel engine fuel system. Background technique [0002] Traditional mechanical fuel injectors have disadvantages such as inflexible fuel injection characteristics, slow response, and poor control accuracy of fuel injection volume due to the restriction of fuel injection characteristics such as fuel injection timing, fuel injection pressure and fuel injection rate by the cam of the high-pressure fuel supply pump. With the increasingly stringent emission regulations, it is difficult to further improve the engine's economy and emission performance. [0003] Compared with the mechanical injector, the electromagnetic control injector applied to the electronic control fuel injection system of diesel engine has faster response speed, flexible and controllable fuel injection characteristics, and more precise control of fuel injection quantity. Although the electromagnetic control injector has impro...

AI Technical Summary

Problems solved by technology

Although the electromagnetic control injector has improved the emission performance of the diesel engine, there are still some shortcomings: the injector usually adopts the form of single-way oil inlet, and the response speed of the needle valve seat is slow, and due to the balance of the diameter of the inlet and outlet holes relationship, it is difficult to further improve the response characteristics; the dynamic oil return in the form of a two-position two-way valve is large, which affects fuel utilization; the axial gap between the needle valve and the control plunger causes static leakage in the injector Fuel problems; in the state of large fuel injection, the uniformity and stability of the fuel injection process of each cylinder is reduced, etc.

Images