New Type Diesel Engine Electronically Controlled Fuel Injector Freewheeling Circuit

Abstract

A new type of freewheeling circuit for electronically controlled fuel injectors of diesel engines, with a low-side drive MOS tube, the source of the low-side drive MOS tube is grounded, the drain is connected to one end of the injector, and the other end of the injector passes through a freewheeling diode Connect the source of the high-side driving MOS tube, the end of the injector is also grounded through an ultra-fast recovery diode, the drain of the high-side driving MOS tube is connected to the VCC power supply, and the drain of the low-side driving MOS tube is also passed through a freewheeling The diode is connected to the VCC power supply. Both ends of the injector are connected to ground through a capacitor. The self-induction electromotive force of the fuel injector of the present invention will not cause negative overshoot at the high end to damage the driving chip of the high-side MOS tube, and at the same time, the self-induction electromotive force will not produce positive overshoot exceeding VCC to destroy the low-side MOS tube. However, the conversion characteristics of the freewheeling circuit will not be affected by the above two diodes, and the safety of the freewheeling circuit can also be improved. Therefore, the control precision of the present invention also meets ideal requirements while ensuring safety and reliability.

Description

technical field [0001] The invention relates to a freewheeling circuit. In particular, it relates to a novel freewheeling circuit of an electronically controlled fuel injector of a diesel engine with a simple and reliable circuit structure. Background technique [0002] The control circuit of the electronically controlled fuel injector of the diesel engine is an executive circuit that directly controls the work of the fuel injector, and is one of the core parts of the ECU of the electronic control system of the diesel engine. Its basic function is to control the opening and closing of the fuel injector and determine the fuel injection law. However, different circuit structures will affect the rate of rise and fall of the injector's on-off current, and the rate of change of the current will determine the speed of the injector's opening and closing (these two periods have uncontrollable time factors, this uncontrollable time The shorter the better), and the stability of the ...

AI Technical Summary

Problems solved by technology

exist figure 2 On the basis of the c circuit, many freewheeling circuits have evolved, such as figure 2 d (D1 in the figure is a transient suppression diode), figure 2 e. figure 2 f (D1 in the figure is a transient suppression diode) circuit, it can be known through a brief analysis that these circuits and figure 2 The c circuit is also a compromise solution, and it cannot obtain the highest precision under the condition of meeting safety and reliability. It is not the best way for the fuel injector freewheeling circuit.

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