Rail pressure control system and control method based on flow valve current

Abstract

The invention provides a rail pressure control method and control system based on flow valve current. The method includes the steps: calculating basic target rail pressure as shown in the specification; correcting the target rail pressure; calculating and judging common rail pressure difference; calculating target driving current of a flow valve; calculating duty ratio; controlling flow valve opening; outputting PWM (pulse-width modulation) wave signals to flow valve driving hardware, controlling flow valve opening and adjusting the quantity of fuel entering a common rail pipe from a high-pressure oil pump metering unit when the common rail pressure difference devi controlled for the i time is smaller than Ps and a target PWM wave duty ratio Duty 2i controlled for the i time is equal to Duty 2i-1; i=i+1 and circularly executing the steps S1 to S6 when i is smaller than N; finishing when i is equal to N or an ECU (electronic control unit) receives stop commands. Power-on currentsampling precision can be improved, high voltage is used for driving at a starting stage, generation of induced electromotive force is inhibited by a differentiating circuit, the current of the flowvalve can reach a preset value in a short time by the aid of the certain opening, current response time is shortened, internal resistance temperature compensation is performed on an electromagnetic coil, and interference caused by internal resistance change is reduced.

Description

technical field [0001] The invention relates to the field of internal combustion engine control or engine control, in particular to a rail pressure control system based on flow valve current and a control method thereof. Background technique [0002] With the increasingly prominent environmental problems, the governments of various countries have tightened the relevant emission regulations of automobile exhaust. The high-pressure common rail system can effectively reduce the emission of the engine because of its high injection pressure and the characteristics of flexible and adjustable injection pressure. It has been more and more widely used in the field of engines. [0003] Rail pressure is an important characteristic parameter of high pressure common rail system, and the change of rail pressure has an important impact on the performance of high pressure common rail system. The regulation of the rail pressure is generally controlled by changing the opening of the flow val...

AI Technical Summary

Problems solved by technology

The disadvantage of this method is that since the control object is the flow valve of the high-pressure oil pump unit, the energized current flowing through the solenoid coil of the flow valve will have an electromagnetic induction effect, and the resistance value of the sampling resistor will change with the ambient temperature. The current value calculated by sampling will deviate from the actual current value, which will reduce the accuracy and response rate of the rail voltage control system

Images