JPS6020572B2 - Electronically controlled fuel injection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is an electronically controlled fuel injection system in which the amount of fuel injected into an engine is determined by the pulse time width of an injection pulse signal applied to an electromagnetic injection valve. Regarding equipment.

Conventionally, in this type of fuel injection device, when the time width of the pulse applied to the electromagnetic injector becomes small, such as during engine deceleration, the activation delay time of the electromagnetic injector cannot be ignored, and this pulse time width and fuel injection amount There is a problem that if the pulse time width becomes less than the response time of the electromagnetic injector, the injector will not open and the fuel will not be supplied.For this reason, the pulse time width will not become less than the predetermined value. The structure was such that the maximum value of the constant pulse time width was determined to be 7 minutes, and the injection valve was operated at this minimum value.

However, this minimum value of 7mln was a constant value. However, since this minimum value of 7mln is a constant value, there are the following drawbacks. That is, it includes an air-fuel ratio sensor that detects the air-fuel ratio based on engine exhaust gas components, and an air-fuel ratio determination circuit that determines whether or not this air-fuel ratio is richer than a predetermined air-fuel ratio. In the fuel injection device to be corrected, if the minimum value of the injection pulse time width is fixed constant, the minimum value ↑min will inevitably be determined to be a little large because the first priority is to ensure the operation of the injector, and the air-fuel ratio will increase. There is a problem in that the air-fuel ratio deviates from the predetermined air-fuel ratio that is desired to be controlled. The present invention aims to solve the above-mentioned problems, and it is possible to change the minimum value of the pulse time width of the injection signal that controls the valve operation of the electromagnetic injection valve as appropriate according to the air-fuel ratio. The present invention provides an electronically controlled fuel injection device that can improve air-fuel ratio control accuracy under various operating conditions. Therefore, the present invention includes a calculation means for calculating an injection signal with a pulse duration corresponding to the fuel injection amount per unit rotation according to the operating state of the engine, and a minimum value signal indicating the minimum value of the fuel injection amount per unit circuit. When the pulse time width of the injection signal generated by the minimum value generation means for generating and the calculation means is larger than the time width of the value signal, this injection signal is output as is, and at the same time it is smaller than the time width of the minimum value signal. a setting means for outputting this minimum value signal as an injection signal, an air-fuel ratio sensor for detecting the air-fuel ratio of the air-fuel mixture supplied to the engine, and the minimum value generating means according to the detection signal of this air-fuel ratio sensor. and switching means for switching the time width of the minimum value signal according to the above, and is configured to control the valve operation of the electromagnetic injection valve in accordance with the injection signal from the setting means.

The present invention will be described below with reference to an embodiment shown in the drawings.

1 is the primary side terminal of the ignition coil for detecting the engine rotation signal, 2 is a frequency dividing circuit that divides the frequency of the rotation signal from this terminal after shaping the waveform, and 3 is input with the engine intake air amount signal Q. This is a calculation circuit that calculates the fuel supply V based on the intake air amount per engine revolution.

5 is a correction circuit that corrects the fuel supply amount based on other parameters of the engine based on the output of the arithmetic circuit 3 input via the OR circuit 4; and 6 amplifies the output of the correction circuit 5 to drive the electromagnetic injection valve 7. This is an output circuit for

8 is a minimum value circuit that outputs the minimum value of the fuel pulse time in synchronization with the signal from the frequency dividing circuit 2, and the output of this circuit 8 is O.
The injection pulse, whichever is greater between the time width of the pulse inputted to the R circuit 41 and output from the arithmetic circuit 3 and the pulse time width of the highest value determined by the minimum value circuit 8, is output to the OR circuit 4.
It is designed to be output from.

Reference numeral 9 denotes an air-fuel ratio sensor that detects the air-fuel ratio based on components in engine exhaust gas.

Kamegawa is an air-fuel ratio determination circuit that determines whether the output of the air-fuel ratio sensor 9 is equal to or higher than a predetermined value, and controls the correction circuit 5 according to the determination circuit of this circuit 10 to correct the amount of fuel injected from the injection valve 7. The air-fuel ratio is adjusted to a predetermined air-fuel ratio. Reference numeral 11 denotes a four-value switching circuit which receives the output of the air-fuel ratio discrimination circuit 10 and switches the output of the minimum circuit 8 depending on whether the air-fuel ratio is below or above a predetermined air-fuel ratio.

FIG. 2 shows the minimum value circuit 8, the minimum value switching circuit 11, and the air-fuel ratio discrimination circuit which are the main parts of the present invention. The minimum value circuit includes resistors 80, 81, 84, 85, capacitor 82,
The minimum value switching circuit 11 consists of a comparator 83,
111, 112, and a transistor j13.

Next, the operation of the above-mentioned fermentation will be explained. During normal engine operation, the intake air amount per engine revolution is large, and the injection pulse width output from the calculation circuit 3 is larger than the technical minimum time width determined by the minimum value circuit 8. The output of the OR circuit 4 is the output of the calculation circuit 3. is output to the correction circuit 5 to cause fuel injection to be performed. On the other hand, when the intake air per revolution of the engine becomes very small, such as during engine deceleration, the injection pulse width of the output of the arithmetic circuit 3 becomes smaller than the maximum value time width of the minimum value circuit 8.

To explain this state below, if the air-fuel ratio sensor 9 detects that the air-fuel ratio is below the predetermined air-fuel ratio (that is, the fuel-air mixture is richer than the predetermined air-fuel ratio), the output of the sensor 9 will be at a high level. Yes, the comparator 10 of the air/fuel discrimination circuit 10
5 becomes the "0" level, the transistor 113 of the minimum value switching circuit 11 becomes non-conductive, and the a of the small value circuit 8 becomes non-conductive.
The potential at the point is as high as a. In this state, when the pulse signal Ti of the frequency dividing circuit 2 shown in FIG. A voltage change with the waveform shown in FIG. 3a occurs. When the potential at point a is 4 points lower than the comparison level c of the comparator 83, the output b of the comparator 83 generates a pulse with a pulse duration of 7 min as shown in FIG. 3b.
It is output from the OR circuit 4. On the other hand, if the air-fuel ratio of the air-fuel mixture changes to a state larger (leaner) than the predetermined air-fuel ratio, the output of the air-fuel ratio sensor 9 will be at a low level, and the output of the comparator 105 of the air-fuel ratio discrimination circuit 10 will be at the "1" level. The transistor 113 of the minimum value switching circuit 11 is conductive, and the minimum value circuit 8
The score of point a changes to a, which is lower than a2. In this state, the pulse signal T from the frequency dividing circuit 2 shown in FIG. 3 (Ti)
When signal i is input, at the falling edge of signal Ti, a voltage change occurs at point a as shown in the waveform diagram on the right side of FIG. 3a. Since the comparison level c of the comparator 83 is constant, the period during which the output of the comparator 83 is at the "1" level is longer than when the air-fuel ratio is smaller than the predetermined air-fuel ratio, generates a pulse with a time width of In other words, when the air-fuel ratio is smaller (richer) than the predetermined air-fuel ratio, the minimum time width is 4. In this case, the minimum time width is slightly increased, that is, the injection time is lengthened to reduce the air-fuel ratio, so that the air-fuel ratio does not vary greatly from the predetermined air-fuel ratio. Note that the output of the air-fuel ratio discrimination circuit 10 is input to the correction circuit 5 regardless of this minimum value switching, and feedback control is performed so that the air-fuel ratio becomes a predetermined air-fuel ratio as in the conventional system.

As described above, the electronically controlled fuel injection device of the present invention adjusts the minimum value of the pulse time width of the injection signal that controls the valve opening operation of the electromagnetic injection valve according to the magnitude of the air-fuel ratio of the Namiai gas supplied to the engine. Since it is configured to switch as appropriate, it is possible to improve the control accuracy of the air-fuel ratio for various operating conditions, and it has the excellent effect of not causing deterioration of exhaust gas components even when the engine is decelerating. play.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is an electric circuit diagram of the main parts of FIG. 1, and FIG. 3 is a signal waveform diagram of each part of FIG. 2. 7... Solenoid injection valve, 8... Minimum value circuit, 9, 10, Vine]
...An air-fuel ratio sensor, an air-fuel ratio discrimination circuit, and a minimum value switching circuit, which form the switching means. Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] 1 A calculation means for calculating an injection signal with a pulse duration corresponding to the fuel injection amount per unit revolution according to the operating state of the engine, and a minimum value signal for generating a minimum value signal indicating the minimum value of the fuel injection amount per unit circuit. When the pulse time width of the injection signal generated by the value generation means and the calculation means is larger than the time width of the minimum value signal, this injection signal is output as is, and
a setting means for outputting the minimum value signal as an injection signal when the time width is smaller than the time width of the minimum value signal; an air-fuel ratio sensor for detecting the air-fuel ratio of the air-fuel mixture supplied to the engine; and switching means for switching the time width of the minimum value signal from the minimum value generating means, and the valve opening operation of the electromagnetic injection valve is controlled in accordance with the injection signal from the setting means. Electronically controlled fuel injection device.