Fuel system control design based on mass conservation

Abstract

Fuel entering and ejecting high-pressure fuel pipe is the basis of fuel engine operation. The intermittent operation of high-pressure oil pump and injector will lead to the change of pressure in high-pressure oil pipe. This paper studies the influence of the opening and closing of one-way value and the speed of cam angle on the pressure in high-pressure oil pipe. Because the fuel flow is unstable in the high-pressure fuel pipe, it is necessary to determine the influence of pressure change on fuel density, and then calculate the mass of fuel supply and fuel injection in unit time. Considering the principle of mass conservation, the problem can be transformed into the length of single opening time of one-way valve when the mass of fuel entering and leaving the high-pressure oil pipe is equal in unit time interval. At the same time, by deducing the influence of the single opening time of the one-way value on the pressure in the high-pressure oil pipe, the single opening time of the one-way valve when the pressure of the high-pressure oil pipe reaches equilibrium after 2s, 5s and 10s is 0.610895ms, 0.425998ms and 0.373376ms respectively. Consider the working principle of the fuel system on the basis of the above considerations. Fit the function relationship between the needle lift and working time, deduce the change rule of flow volume of injector with time, and calculate the volume and mass of fuel injected by the injector in the working cycle. The results show that the high-pressure oil pump supplies oil 94 times in a working cycle of the injector, and the time required for the cam to rotate for one circle is 1.064ms, and the angular velocity of the cam is 5.906rad/ms. In this paper, based on the theory of unsteady liquid motion, mass conservation and energy conservation of fluid mechanics, many elements involved in the problem stem are analysed and related, and the control model of one-way valve switch and cam angular velocity is given.