JPS608333B2 - Electronically controlled fuel injection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement of an electronically controlled fuel injection device that calculates a basic injection time width depending on a signal synchronized with the engine rotation speed, and particularly relates to an improvement in an electronically controlled fuel injection device that calculates a basic injection time width depending on a signal synchronized with the engine rotation speed. This is suitable for this type of device that increases the amount of fuel.

Conventional electronically controlled fuel injection systems usually have a starting auxiliary valve that operates only during starting in order to obtain good engine starting performance at low temperatures. There is.

However, this method requires a starting auxiliary valve, a temperature/time switch to control the valve opening time, etc., which increases the cost of the device. developed and proposed. However, many of these systems require complex electronic circuits, or there is insufficient matching between the amount of fuel supplied and the amount of fuel required by the engine, and there is no system that has a simple configuration that provides sufficient matching. . The present invention aims to solve these problems, and in order to determine the closing time of the fuel injection valve, the storage means is activated in response to a first pulse signal having a time width corresponding to the engine rotation speed. In an electronically controlled fuel injection device in which a second pulse signal having a basic injection time width is formed by repeating an accumulation increase/decrease operation, the time width of the first pulse signal is decreased by a predetermined time width to form a second pulse signal having a basic injection time width. By providing a correction means for correcting the basic injection time width of the pulse signal, and a correction command means for causing the correction means to perform the time width correction operation of the first pulse signal at the time of starting the engine, At a very low starting speed, a sufficiently rich fuel can be supplied to the engine, and as the speed increases, the amount of fuel supplied can be rapidly reduced in conjunction with the action of the correction means, so that It is an object of the present invention to provide an electronically controlled fuel injection device that can further optimize air-fuel ratio characteristics at engine startup without using a special configuration as in the past.

The present invention will be explained below based on one embodiment.

In this embodiment, an ignition signal is picked up from the ignition system of an internal combustion engine, and this ignition signal is waveform-shaped and further divided into a rectangular wave signal synchronized with the engine speed (Ne). After this rectangular wave signal is passed through a delay circuit, a basic pulse width calculation circuit (the ratio of intake air amount Qa to engine speed Ne
(to obtain the basic pulse width tp according to the basic pulse width tp). As a result, the basic pulse width of the fuel, tp, becomes Qa(1-cQt
o·Ne)/Ne.

However, the delay time "C" is a constant. Therefore, the air-fuel ratio supplied to the internal combustion engine is ~ conventional intake air amount Qa
Although it was determined by the characteristics of Ne, it is also a function of Ne determined by the delay time law o.

Furthermore, by actually operating the above-mentioned delay circuit only when the internal combustion engine is started, the fuel is richer than the air-fuel ratio determined by the intake air amount Qa at low engine speeds when the internal combustion engine is started. supply to improve engine startability.
In FIG. 1, 1 is a terminal to which a primary ignition signal is applied from the ignition system of an internal combustion engine, for example, 2 distributor points, and the primary ignition signal is as shown in FIG.

2 is a waveform shaping/frequency dividing circuit which shapes the pulse signal applied to terminal 1 into a rectangular wave to prevent malfunction, and then divides the frequency according to the number of fuel injections per engine revolution of 2.

FIG. 2 shows a waveform shaping signal, and FIG. 2 shows a signal frequency-divided by one-third in a six-cylinder engine. 3 is a time width correction circuit, which keeps the leading edge of the rectangular wave signal from circuit 2 constant when the starter switch terminal W is applied with a "1" level star signal. Delay by an amount of time.

FIG. 3 shows a specific example of this time width correction circuit 3. Waveform shaping applied to input terminal 30', frequency division 3
A known monostable multipipulator 31 is triggered in synchronization with the leading edge of a rectangular wave signal from the circuit, and its output is inputted to an AND gate 33 through an inverter 32, and the output of the waveform shaping and frequency dividing circuit is input to an AND gate. Put it in 33.

The monostable multi-pipe relay 31 is activated only when the starter switch is activated, and the output of the monostable multi-pipe relay 31 is always reduced to the ``0'' level when the starter switch is shut off. When the switch is activated, a signal whose time width is shortened by a certain period of time is obtained at the output terminal 84 as shown in FIG. 2 and 4. When the starter switch is not conducting, the signal at the input terminal 3Q appears as it is at the output terminal 34. Furthermore, in Fig. 1, 6 is an arithmetic circuit which calculates the intake air amount of the engine by using a rotation signal synchronized with the engine rotation via the time width correction circuit 3 and a signal corresponding to the intake air amount from the intake air amount meter 6. A pulse signal TI having a time width divided by the number is generated.

The time width of this pulse signal TI is inversely proportional to the engine speed and is 1
It is proportional to the amount of air sucked into each cylinder in one stroke. The arithmetic circuit 4 uses, for example, a multi-pipe plate with a variable pulse time width as described in Japanese Patent Application Laid-Open No. 49-67016, and the charging of the capacitor is controlled by the pulse signal passed through the time width correction circuit 3, and the discharge thereof is controlled. It is controlled by the intake air amount meter 61. 2.5 shows the charging and discharging waveforms of the capacitor in the arithmetic circuit 4, and FIG. 2 shows the output pulse signal. As described above, when the starter operates, the rectangular wave signal is shortened in the time width correction circuit 31, so that the output pulse signal TI' is shortened by the time width tp' shown by the solid line. Further, in the arithmetic circuit 5, the input signal from the air flow meter 6 is fixed at a constant value corresponding to a large amount of intake air when the starter is operated, so that a rich air-fuel mixture necessary for starting can be obtained.

FIG. 4 shows the air amount sensor 6 and a clamp circuit connected to the multipipelator described above. Air flow meter 6
The signal is formed by resistors R1, R2 and 3, resistors R and R3 are fixed resistors, and variable resistor R2 has a resistance value that changes depending on the amount of intake air.
The configuration is such that the slope of the discharge of the capacitor described above is changed depending on the ratio to the potential difference between the ground and the ground. Resistance R4, R5?
R6, R7, R8 "Diode ○17D2?D3, transistors Trl, Tr2, Tr3 constitute a clamp circuit, and the starter switch conducts and outputs "1" to terminal 4.
When a level occurs, transistors Trl, Tr2, Tr3
is conductive, and the level at point B is clamped by diode ○2 due to the conduction of transistor Tr, and the signal to the multipipulator is fixed at a potential determined by resistors R2 and R3, and the relationship with the intake air amount is determined. cut off. On the other hand, when the starter switch is shut off, transistors Trl, Tr2, Tr
3 is cut off, and the signal at point B is guided to the multipipulator. Furthermore, in FIG. 1, 7 is a multiplier circuit which inputs various signals from the operating state detection means 8 that detects the engine cooling water temperature, intake air temperature, etc. to the pulse time width of the pulse signal TI output from the arithmetic circuit 5. A pulse signal T2 whose pulse time width is corrected by arithmetic calculation using a known method is output.

Note that the terminal 4 of the starter switch is connected to the detection means 8 in order to perform fuel correction after the starter is stopped, that is, to increase the amount after starting. 9 is a voltage correction circuit which inputs the pulse signal T2 from the multiplier circuit 7, corrects the change in fuel injection amount of the electromagnetic injection valve 11 depending on the power supply voltage, and generates a pulse signal T3 with a time width corresponding to the power supply voltage. Output.

101 is an OR circuit and an output circuit, and the arithmetic circuit 5,
Pulse signal T from multiplication circuit 7 and voltage correction circuit 8
1, T2, T3 and calculate the pulse time width (TI + T2
A pulse signal T (T3) is generated, amplified, and then supplied to the electromagnetic injection valve 11.

In the above-mentioned configuration, when the ``11 level signal'' is applied to the starter switch terminal 4 when starting the engine, the waveform shaping,
The rectangular wave signal from the frequency dividing circuit 2 is shortened by the delay time in the time width correction circuit 3 as shown in FIG. Therefore,
The basic pulse signal TI, which is the output of the arithmetic circuit 5, has a time width tp expressed by the following equation. First, if the time width of the rectangular wave signal of the waveform shaping circuit 2 is ro, then To=K/Ne
(K is a constant), and tp is tpQa(To-to
)=Qa(KノNe-to)=KOQa(1-tocN
e/K)/Ne, that is, “tp is Qa(11c.

to・Ne)Ne. However, Qa is the output voltage of the intake air flow meter 6, Ne2 is the engine speed, to is the delay time,
C is a constant.

On the other hand, when a "1" level signal is applied to the starter switch terminal 4, the signal Qa from the air flow meter 6 input to the arithmetic circuit 5 is fixed at a constant value Qa'', which corresponds to a large amount of air. 2 Therefore, the injection pulse signal T, which represents the amount of fuel injection supplied to the engine, changes mainly depending on the engine speed, and when the rotation speed is slow, it is difficult to supply sufficiently rich fuel to the engine. "And when the internal combustion engine explodes and its rotational speed increases as it reaches complete explosion, the time width of the rectangular wave signal, which is the output 3 of the time width correction circuit 3, always changes to a constant time width to
As a result, the amount of charge of the capacitor in the multipipulator described above decreases, and the time width of the injection pulse signal T rapidly decreases.

When the start is completed and the signal 3 applied to the starter switch terminal 4 reaches the "0" level, the operation of the time width correction circuit 3 stops, and the rectangular wave signal from the waveform shaping and frequency dividing circuit 2 is directly sent to the arithmetic circuit. At the same time, the air flow meter 6 starts inputting signals, so the basic pulse signal T4, which is the output of the arithmetic circuit 5, the engine speed Ne and the intake air flow Qa.
It is determined depending on.

FIG. 5 is a characteristic diagram showing the operation of the time width correction circuit 3, and shows the change in pulse width with respect to the engine speed when the amount of intake air is constant.

Curve a shows the state when the time width correction circuit 3 is inactive, that is, the delay time to is zero, and when the time width correction circuit 3 is activated and the delay time to occurs, the curve shifts to curve b. In addition, if multiple values of delay time ■ are set, the curve cQd
It is possible to change the characteristics as follows. Further, according to the present invention, for example, the starter switch for switching between activation and deactivation of the time width correction circuit 3 in the above-described embodiment is set to "1" when the engine speed is higher than the set value or lower than the set value. By replacing it with a rotation speed detection circuit that generates a level signal, it is also possible to change the air-fuel ratio according to the engine rotation speed.As described above, according to the present invention, the air-fuel ratio can be changed depending on the engine rotation speed. In an apparatus in which a second pulse signal having a basic injection time width is formed by repeating the accumulation increase/decrease operation of an accumulation means in response to a first pulse signal having a width, "When starting the engine, the time of the first pulse signal is By reducing the width by a predetermined time width, it is possible to change the accumulation increase/decrease characteristics of the accumulation means by apparently manipulating the engine speed. The characteristic of rapid thinning as the rotational speed increases can be easily provided, which is extremely beneficial for starting systems using only the main injector.

[Brief explanation of drawings]

Fig. i is a block diagram showing one embodiment of the device of the present invention, Fig. 2 is a time chart showing the operation of the device shown in Fig. 1, and Fig. 3 is a detailed configuration diagram of the time width correction circuit 3 in Fig. 1. 4 is a detailed configuration diagram of a part of the intake air amount meter 6 and arithmetic circuit 5 in FIG. 1, and FIG. 5 is a characteristic diagram for explaining the operation of the device of the present invention. 1...distributor point, 2...waveform shaping,
Frequency dividing circuit, 3... Time width correction circuit ~ 4... Starter switch terminal serving as correction command means, 5... Arithmetic circuit. Figure 1 Figure 2 Figure 3 Figure 4 Figure 5

Claims (1)

[Claims] 1. In order to determine the opening time of the fuel injection valve, a second pulse signal having a basic injection time width is generated by repeating the accumulation increase/decrease operation of the accumulation means in response to the first pulse signal having a time width corresponding to the engine speed. In the electronically controlled fuel injection device, the correction means corrects the basic injection time width of the second pulse signal by reducing the time width of the first pulse signal by a predetermined time width, and the correction means an electronically controlled fuel injection device, comprising correction command means for causing a time width correction operation of the first pulse signal to be performed at engine start-up.