Piezoelectric fuel injector with variable fuel injection laws

Abstract

The invention aims to provide a piezoelectric fuel injector with variable fuel injection laws. The piezoelectric fuel injector with the variable fuel injection laws comprises a pressurization controlvalve part, a three-level piston assembly, a fuel injection control valve part, a needle valve part and a fuel injector body. A pressurization control valve structure is adopted to control a pressurization area of a three-level piston, so that different supercharge ratios are effectively realized, and the fuel injection law is more flexible. The action process of a needle valve is driven by a piezoelectric stack, the response speed of the needle valve is fast, the control freedom degree is large, the fuel injection laws are flexible and controllable, and the power performance of a diesel and the economical efficiency of fuel are effectively improved, so that the diesel meets the more strict emission regulation. A hydraulic compensating piston structure is used for topping up of the fuel when a control cavity releases voltage, the function of two-way fuel feeding is achieved during voltage buildup, so that the fuel injection law realizes the specialty of slow-first and urgent-last, andthe 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] The mechanically controlled fuel injector has the advantages of high reliability and simple structure. However, because its fuel injection characteristics such as fuel injection timing, fuel injection pressure and fuel injection rate are restricted by the cam profile of the high-pressure fuel supply pump, it has disadvantages such as inflexible fuel injection characteristics, slow response, and poor control accuracy of fuel injection volume. . With the increasingly stringent emission regulations, it is difficult to further improve the economy and emission performance of the engine, nor can it meet the requirements of the current market for the engine. [0003] Compared with the mechanically controlled injector, the electromagnetically controlled injector used in the electronically controlled fuel injection system of a diesel engine ha...

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 problem; due to the inductance of the solenoid valve coil, there is a certain lag time in its response, which leads to the limitation of the further increase in the number of fuel injections, and the repeatability of fuel injection needs to be improved, etc.

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