Single-chip fuel injection pump speed and advance angle of high-precision measurement
2022-11-19 13:06:31
Abstract: This paper introduces the hardware circuit design and software program flow chart of measuring the speed and advance angle of injection pump with single-chip microcomputer with high accuracy. It has high reference value for similar system. Nanyang Institute of Technology Xue Qingji Wang Xi  Daqing Petrochemical Branch Li Ning 1 Introduction Injection advance angle refers to the engine is running, the injector nozzle to the cylinder at the moment of injection (nozzle needle valve raised to mark) to the piston line Crank angle to top dead center. Used in advance with the fuel supply angle instead. Due to wear and tear on the diesel fuel injection pump cam drive, the advance angle will change. In addition, the engine cylinder liner, piston wear or crankshaft, connecting rod in the boring or replacement, it will make the lead angle deviation from the normal combustion required value. Therefore, the engine is in use, fuel injection advance angle need to be checked or adjusted frequently. Accurate measurement of the value of advance angle is the key to accurate adjustment. This article describes the use of single-chip measurement of advance angle method, with high accuracy, wide range, simple features. 2 Measuring principle In the test bed motor spindle and fuel pump were fixed a photoelectric sensor, the optical pulse by the photoelectric circuit into electrical pulses, respectively, with N1 and N2 said. 8051 MCU Timer / Counter 0 is set to work mode 2, which automatically reloads the initial value 8-bit timer / counter and sets the TMOD control bits GATE = 1 and TRO = 1 to enable the Timer / Counter 0 operation to be controlled by INT0. The spindle speed is calculated from the results of the measurement circuit shown in Figure 1. Figure 3 shows the advance time measurement circuit to measure the normal operation of the pump at a certain speed pulse N1 and pulse N2 difference T, calculate the advance angle. Since the absolute error of one revolution of the measurement spindle is only one reference pulse period (1 s), the relative measurement error of the rotation speed is small. (1) Spindle speed measurement The pump runs at a certain speed, the optical encoder pulse signal NO from measuring the spindle speed reaches the P3.4 pin of 8051, and the P3.4 pin pulse signal is detected by the singlechip and P1.0 The pin is high, D flip-flop in the next NO pulse rising edge, Q output high,  INT0  to start the timer T0, with R0, R1 record the number of timer interrupts, timer T0 timer A period of time t (the time should be less than the interval between the two rising edges of the NO pulse), the time to request the CPU will P1.0 feet low, the timer T0 continue to work, start recording time Δt, D flip-flop wait The next rising edge of NO pulse to the Q-terminal output low, INTO the timer T0 stop working. The CPU calculates the total time T between the rising edges of NO for two consecutive pulses, which is the time at which the spindle rotates one revolution so that the spindle speed is 1 / T. (2) Measurement of advance angle The pump runs at a certain speed, the optical encoder pulse signal NO from measuring the spindle speed reaches P3.4 of 8051. The single-chip microcomputer detects the pulse signal of P3.4 pin and sets P1.0 Pin is high, D flip-flop in S next pulse (N1 pulse) rising edge, Q output high,  INT0  so that the timer T0 began to work with R0, R1 record the number of timer interrupts, The timer T0 is timed for a period of time t (the time should be less than NO, the interval U between the two rising edges of the N1 pulse immediately), and when it is time to request the CPU to set P1.0 pin low, the timer 0 continues to work, Start recording time Δt. D flip-flop waits for the next S pulse rises, Q low output, INT0  to stop the timer T0. The CPU calculates the total time T (t + Δt), which is the advance time of NO over N1. In accordance with the method of measuring the rotational speed of the spindle to measure the time required A, and then use the formula: advanced = T / A to calculate the advance. 3 measurement subroutine flow chart below is given the spindle speed measurement subroutine flow chart, advanced angle measurement can refer to this flowchart. 4 Conclusion The method described in the two oil pump test bench plant production of more than 30 sets of oil pump test bench running reliable, accurate measurement, fully meet the test requirements. The system of other systems speed and time of high-precision measurement of a certain reference value. 5 References [1] "Single-chip microcomputer principle and application" [M]. Ding Yuanjie editor of Machinery Industry Press .1996,10 [2] "Microcomputer Technology and Application" [M]. Dai Mei Calt Shi Jiaquan Tsinghua University Press .1996 5
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