JPH024040B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for preventing malfunction of an electronically controlled internal combustion engine, and in particular to a method for preventing malfunction of an electronically controlled internal combustion engine, in which the fuel injection timing or ignition timing is calculated using a computer. Concerning methods for preventing malfunctions due to influence.

In electronically controlled internal combustion engines in which the fuel injection timing or ignition timing is controlled by a computer, the required amount of fuel corresponding to the amount of intake air detected by an air flow meter is conventionally determined by metering, and the injection pulse is determined based on this. The width was determined and controlled so that the required amount of fuel was injected from the fuel injection valve according to the ignition signal. In addition, in electronically controlled internal combustion engines using a digital computer, instead of the ignition signal, a specific rising signal with a signal interval time that is synchronized with the engine crank angle is synchronized with the top-dead-center (TDC) time of the crankshaft. Based on this time, the fuel injection timing or ignition time is calculated, and the fuel injection valve is controlled to inject the required amount of fuel corresponding to the intake air amount detected by the air flow meter, and the spark plug is energized. , which controlled the ignition time. However, if noise is superimposed on the signal interval that occurs every 30 degrees of crank angle for some reason, such as grounding not being completely separated, then the calculated fuel injection start timing or energization , causing a shift in ignition timing and causing malfunction. Although a difference in fuel injection start timing does not have a great effect on engine performance, a difference in energization and ignition timing can cause knocking and have an adverse effect on exhaust gas purification performance.

An object of the present invention is to provide a control system (for example,
The objective is to prevent malfunctions (fuel injection start timing, energization, ignition timing) from occurring.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a schematic diagram of an internal combustion engine controlled by a digital computer. In FIG. 1, the fuel system of an internal combustion engine 1 includes a fuel injection valve 2, a fuel tank 3, a fuel filter 4, a fuel pump 5, a pressure regulator 6, a solenoid register 7, and the like. The fuel injection pulse of the fuel injection valve 2 is given by a digital computer 10. Sensors for detecting various operating conditions of the internal combustion engine, namely, an air flow meter 11 that detects the amount of intake air, an intake temperature sensor 12, a throttle opening sensor 13, an intake pressure sensor 14, a water temperature sensor 15, and an exhaust gas concentration sensor. An O ₂ sensor 16, a rotation angle sensor 17, and the like are provided, and these signals are input to the digital computer 10. 18 is a power supply for the digital computer 10, and 19 is an igniter that determines the ignition timing of a spark plug (not shown), which is controlled by a signal from the digital computer 10.

The rotation angle sensor 17 utilizes an electromagnetic pickup or magnetic resistance, and generates a pulse signal synchronized with the angle of the engine crankshaft (not shown). By inputting this signal to the digital computer 10, the computer 10 can set, for example, crank angle synchronization signal time intervals (T ₁ , T ₂ , ..., Tn) every 30 degrees as shown in FIG. Can be done. Note that FIG. 2 shows a pulse waveform based on time.

Figure 3 shows the pulse waveform of the control system based on the crankshaft angle, Figure 4 shows the relationship between the crank angle and fuel injection timing, and Figure 5 shows the relationship between the crank angle and ignition timing. It shows the relationship. In these figures, the 360°C A signal is a pulse waveform generated every revolution of the crankshaft. 30
The ℃A signal is a pulse waveform that occurs every 30 degrees of the crankshaft, and the time interval of this signal is defined as T ₁ , T ₂ , ..., Tn
(Figure 2). In addition, a 4-cylinder engine has a third
The falling point of signal 1 in the figure is the top depth center (TDC) point of #1 and #4 cylinders, and signal 7 is
The falling point of is set to the TDC point of #2 and #3 cylinders. Based on this TDC point, signal 1
The fuel flow rate is calculated from the time of the zero falling signal, and based on this, the start and end times of the fuel injection pulse are calculated (FIGS. 3 and 4). Similarly, the energization ignition timing is calculated at the time of the falling signal of signal 1 (same as the time of TDC) using the time of TDC as a reference (FIGS. 3 and 5). Note that these points of time are memorized.

By the way, noise is superimposed on the synchronization signal time interval (T ₁ , T ₂ , ..., Tn) for every 30 degrees of crank angle, and while the noise remains superimposed, the crank angle synchronization signal time interval (T ₁ , T ₂ , ..., Tn) into the calculation of fuel injection timing or energization ignition timing, it may cause malfunction as described above. Therefore, in the present invention, the time interval with noise is determined as follows, and if noise is present, that time interval is excluded from the calculation of fuel injection timing or energized ignition timing. I made it.

Figure 6 shows the crank angle synchronization time intervals (T ₁ , T ₂ ,
This is a flowchart for determining whether noise is superimposed on ..., Tn). First, find the latest 30° crank angle signal interval time T _(o+1) . Next, find the comparison time T _(REF) for noise detection. this
T _(REF) is calculated using the following formula.

T _(REF) = T (n) − 2T _(R) ……(1) Here, the crank angle synchronization signal time interval (T ₁ ,
Since T ₂ ...Tn) changes depending on engine rotational fluctuations, by equation (2), _the average value (T _(R) ), and since the minimum time of the latest 10° crank angle signal interval time T _(o+1) is expected to be at least equal to or greater than Tn minus 2T _(R) , the formula ( 1) to find T _(REF) .

When T _(o+1) > T _(REF) , it is determined that noise is not superimposed, or even if it is superimposed, its influence is very small, and the 30° crank angle at that time is determined. In order to update the data on which the calculation is based using the signal interval time, proceed to the next processing program.

Also, when T _(o+1) ≦ T _(REF) , it is determined that noise is superimposed, and the 30° crank angle signal interval time at that time is not used for data update, and the program It will be the end.

In this way, in the present invention, since the crank angle interval time on which noise is superimposed is excluded from the data on which the calculation is based, the calculation of the fuel injection timing or the ignition timing is not affected by the noise. This has the effect of preventing temporal malfunctions of the fuel injection valve and ignition timing, thereby preventing knocking of the engine, and ensuring that the exhaust gas purification function is properly performed.

In addition, in the above formulas (1) and (2), n is 5 to 10
It was found through experiments that it is appropriate to

[Brief explanation of drawings]

Figure 1 is a schematic diagram of an internal combustion engine controlled by a digital computer, Figure 2 is a diagram showing the crank angle synchronization signal time interval every 30 degrees, and Figure 3 is a diagram showing the control system pulses based on the crank angle. Figure 4 shows the relationship between the crank angle and fuel injection timing, Figure 5 shows the relationship between the crank angle and ignition timing, and Figure 6 shows the relationship between the crank angle and the ignition timing. This is a flowchart. 1... Internal combustion engine main body, 10... Digital computer, 17... Crankshaft rotation angle sensor, 19
...Ignita.

Claims (1)

[Claims] 1 An electronically controlled internal combustion engine in which the fuel injection timing and/or energization ignition timing is calculated by a computer based on the signal interval time (T ₁ , T ₂ ...Tn) synchronized with the crankshaft angle of the internal combustion engine, and Calculate the signal interval time T _(o+1) and the comparison time T _(REF) for noise detection, and if T _(o+1) ≦T _(REF) , there is noise in the input signal at that signal interval time. A method for preventing malfunction of an electronically controlled internal combustion engine, characterized in that it is determined that there is overlap and the data is excluded from calculation data.