JPH0160663B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION This invention provides fuel supply for an internal combustion engine (hereinafter also referred to as engine) into an intake passage by metering fuel regulated to a constant pressure by controlling the opening and closing of a solenoid valve by an electronic control circuit. It is related to the device.

Conventionally, in fuel metering control using a solenoid valve, an injection control signal is output based on a frequency pulse signal synchronized with engine rotation and a pressure signal corresponding to the pressure in the intake pipe, and injection is performed by controlling the opening and closing of the solenoid valve. Fuel was being measured. This method of fuel supply allows optimal fuel control when the engine speed is high or while driving, but when the engine speed is low and idling, the engine speed fluctuates and the amount of fuel supplied becomes unstable. Not yet. In other words, in order to supply fuel according to the fluctuation of the engine rotation,
At that time, an amount of fuel different from the amount required by the engine is supplied, increasing engine rotational fluctuation. Therefore, in order to maintain stable engine rotation, the engine speed during idling must be set to a high value, leading to a worsening of fuel consumption.

In order to solve the above-mentioned problems, this invention stabilizes the rotation of the engine during idling, sets the idling speed to a low value to improve the fuel consumption rate, and provides a vehicle-mounted internal combustion engine with good feeling. The purpose is to provide an electronically controlled fuel supply system.

This invention will be explained based on drawings of embodiments. In FIG. 1, 1 is an engine, 2 is an intake pipe, and 3 is a fuel supply device. In the fuel supply device 3, 4 is a throttle body, and the upper end is an air
It is connected to a cleaner (not shown), and its lower end is connected to an intake pipe 2 and continues to the engine 1. The inside of the throttle body 4 is an intake passage 5.
A valve housing 7 supported at the tip of the fuel passage 6 is provided in the upper part. A solenoid valve 8 driven by an electronic control circuit 10 is mounted inside the valve housing 7, and a fuel nozzle opens at the bottom of the figure. The upstream portion of the fuel passage 6 is fixed through the side wall of the throttle body 4, and introduces fuel supplied from a fuel pump (not shown) to the solenoid valve 8. A throttle valve 9 is provided at the bottom of the intake passage 5. Throttle sensor 11 is throttle valve 9
Detects opening changes in conjunction with A pressure sensor 12 that detects pressure and an intake air temperature sensor 13 that also detects temperature are installed in the intake pipe 2. The engine 1 is equipped with a water temperature sensor 14 that detects the temperature of the engine 1, and an air-fuel ratio sensor 1 that detects the oxygen concentration of exhaust gas.
5 is attached to the exhaust pipe 16.

Here, the conventional configuration of the electronic control circuit 10 will be explained with reference to FIG. The rotation speed sensor 17 is of an electromagnetic pickup type that detects passage of a protrusion provided on the crankshaft of the engine 1. However, other types may be used, such as a combination of a rotor with magnet pieces and a Hall element. Rotation speed sensor 17
The signal from TP passes through the waveform shaping circuit 19 and is input to the basic arithmetic circuit 20 together with the signal from the pressure sensor 12 of the intake pipe 2.
can be determined. The waveform shaping circuit 19 may be a known one (for example, a Schmitt circuit). Throttle・
Each signal detected by the sensor 11, pressure sensor 12, and water temperature sensor 14 is input to a correction circuit 21 and subjected to calculation processing. Each signal from the basic calculation circuit 20, intake air temperature sensor 13, water temperature sensor 14, air-fuel ratio sensor 15, and correction circuit 21 is processed by the multiplication circuit 22, and the energization pulse width Tm
is made. At the same time, in synchronization with the timing at which the pulse width Tm expires, an injection correction pulse width Tv is generated by a pulse generation circuit 23 that generates an injection correction pulse using the voltage of the battery 18. The energizing pulse width Tm and the injection correction pulse width Tv are added by the adding circuit 24, and the injection pulse width T=Tm+
The signal becomes a Tv injection pulse signal, is amplified by the output circuit 25, sends a valve opening signal to the electromagnetic valve 8 in synchronization with the rotation of the engine 1, and opens the nozzle to inject fuel while metering it.

In the configuration of the conventional fuel supply device as described above,
When the engine 1 is idling, the rotation is fluctuating, so if fuel metering is controlled by the number of pulses synchronized with the rotation, when the rotation speed swings toward the higher side, the number of pulses will increase and the amount of fuel will increase. The rotation speed will be even higher. Similarly, when the rotational speed swings to the lower side, the rotational speed becomes even lower. Furthermore, since the basic arithmetic circuit 20 receives a signal from the pressure sensor 12 along with a waveform determined by the rotational speed, the injection control signal fluctuates even more under the influence of the fluctuating pressure in the intake pipe.
In this way, the fluctuation in the rotational speed becomes large, and stable idling rotation cannot be obtained.

Next, an embodiment according to the present invention will be described with reference to FIG. FIG. 3 shows an arithmetic circuit including a control unit 26, which is different from the conventional configuration shown in FIG. This is a modified version of the input section 20. The control unit 26
It consists of a switch 27 and an injection timing control circuit 28. Signals from the rotation speed sensor 17, idle switch 27, and pressure sensor 12 are input to the control circuit 28, and two signals are output to the basic calculation circuit 20. The idle switch 27 may be any known on/off switch that indicates idling of the throttle valve 9. An embodiment of the injection timing control circuit 28 is shown in FIG. The waveform shaping circuit 19 outputs the signal from the rotation speed sensor 17 and outputs the signal to the pulse frequency switching circuit 29 and the frequency comparison circuit 30. Switching control circuit 31
are frequency comparison circuit 30, idle switch 2
7. Input each signal from the voltage comparison circuit 37,
Pulse frequency switching circuit 29 and voltage switching circuit 3
A signal is output to each of the terminals 6 and 6. The signal from the constant frequency pulse generation circuit 32 is sent to the pulse frequency switching circuit 2.
9 is input. A signal is output from the pulse frequency switching circuit 29 to the basic arithmetic circuit 20. A signal from the pressure sensor 12 is input to a voltage switching circuit 36 and a voltage comparison circuit 37. Voltage switching circuit 36
inputs signals from the switching control circuit 31, pressure sensor 12, and constant voltage generation circuit 38, and outputs the signals to the basic arithmetic circuit 20.

FIG. 5 shows an injection timing control circuit 40 of another embodiment. The difference from FIG. 4 is that there is no constant frequency pulse generation circuit 32, and instead there is a circuit that connects the waveform shaping circuit 19 to the pulse frequency switching circuit 29 through the FV conversion circuit 33, the averaging circuit 34, and the VF conversion circuit 35. is formed. Also, constant voltage generation circuit 3
8 is not provided, and instead a circuit is formed that connects the pressure sensor 12 to the voltage switching circuit 36 through the averaging circuit 39. The averaging circuits 34 and 39 may be constructed of known capacitors.

FIG. 6 shows the injection timing control circuit 28 (fourth
Figure 1) shows one row of the circuit diagram. Frequency comparison circuit 30
are FV conversion circuit 33, resistors 41a, 41b, 4
2a, 42b, voltage comparators 45, 46, etc., and outputs the input from the waveform shaping circuit 19 to the switching control circuit 31. The voltage comparison circuit 37 includes a resistor 43
a, 43b, 44a, 44b, voltage comparator 47,
48, etc., and outputs the input from the pressure sensor 12 to the switching control circuit 31. The constant frequency pulse generating circuit 32 may be a known flip-flop circuit, and the pulse frequency switching circuit 29 and voltage switching circuit 36 may have a known circuit configuration as shown in FIG.

In the fuel supply device 3 configured as described above, when the engine 1 is in a load operating state, the control unit 26 shown in FIG.
7 and a pressure sensor 12 that outputs a voltage according to the pressure of the intake pipe 2 (FIG. 1) are input to perform optimal fuel control.

When the engine 1 is idling, a pulse frequency corresponding to a constant rotation speed and a voltage corresponding to a constant intake pipe pressure are output to the basic arithmetic circuit 20. That is, in the injection timing control circuit 28 in FIG.
Also output to. This frequency comparison circuit 30 outputs an ON signal to the switching control circuit 31 when the engine speed is in a frequency range corresponding to a predetermined speed range including the idling speed. The pressure sensor 12 also has a voltage switching circuit 3 that responds to the pressure in the intake pipe 2.
At the same time, it is output to the voltage comparator circuit 37. This voltage comparison circuit 37 is connected to the pressure sensor 12.
When the signal from the switch indicates a predetermined pressure range including the pressure in the intake pipe 2 during idling, an ON signal is output to the switching control circuit 31. The switching control circuit 31 is
In addition to the above two signals, idle switch 27
When these three signals are on, an on signal is output to the pulse frequency switching circuit 29 and the voltage switching circuit 36. At this time, the pulse frequency switching circuit 29
At the same time, the voltage switching circuit 36 outputs a constant frequency pulse waveform from the constant voltage generating circuit 38 to the basic arithmetic circuit 20.
Output to 0. Since the subsequent steps are the same as before, the explanation will be omitted.

In the injection timing control circuit 40 shown in FIG.
9, the signal from the waveform shaping circuit 19 is sent to the FV converter 3.
3, the frequency is converted into a voltage, this voltage signal is averaged by an averaging circuit 34, and this averaged voltage signal is further passed through a VF converter 35, thereby changing the frequency of the waveform shaping circuit 19. Pulses with large fluctuations are input as a pulse signal having an averaged frequency. At the same time, pressure sensor 12
Signals with large fluctuations from the voltage source pass through the averaging circuit 39 and are input to the voltage switching circuit 36 as an averaged voltage signal. Since the subsequent steps are the same as those in the embodiment shown in FIG. 4, the explanation will be omitted.

The injection timing of the embodiment shown in FIG.
It will look like the figure. Figure A shows instantaneous pressure fluctuations in the intake pipe 2 when the engine is in an idling state, using the output of the pressure sensor 12. Figure B shows the instantaneous engine speed. The solid lines in A and B are the conventional example (Fig. 2). That is, the intake pipe pressure and engine speed fluctuate in a wave-like manner. Here, the idling speed setting value is 600rPm,
Even if the intake pipe pressure negative pressure at that time is -540 mmHg, if the conventional control circuit is used to control the engine, the synchronous injection state shown in Figure C will be achieved. In other words, the timing intervals and widths become inconsistent. On the other hand, in the embodiment shown in FIG. 4 of this invention, when the engine 1 is in an idling state, for example, the intake pipe pressure is -540 mmHg
The pressure sensor output 1.0V corresponding to 1.0V is set in the constant voltage circuit 38, and at the same time
20 flip-flop oscillations equivalent to 600rPm
If Hz is set in the constant frequency pulse generation circuit 32, when the ON signal is input from the switching control circuit 31, the 20
Hz, 1.0V periodic constant pressure injection is performed. This timing becomes constant as shown in FIG. When the rotation of the engine 1 fluctuates and tries to increase, the rotation speed does not increase because the fuel does not increase accordingly, and when the rotation tries to decrease, it becomes the same state as if the fuel had increased, so the rotation must be maintained. to work. In this way, the idling rotation of the engine 1 is in a very stable state with little vibration, as shown by the broken line in FIG.

FIG. 8 shows the injection timing of the embodiment of FIG. The solid lines in A and B in the same figure represent the case of control using the conventional control circuit (FIG. 2). If this is controlled by this embodiment, the rotation speed of the engine 1 will be
By passing it through the FV conversion circuit 33, the averaging circuit 34, and the VF conversion circuit 35, timing corresponding to the average rotation speed of the engine 1 can be obtained. Furthermore, by passing the output of the pressure sensor 12 through the averaging circuit 39, an output corresponding to the average pressure of the intake pipe 2 can be obtained. When a signal is input from the switching control circuit 31 due to such an output, average period average pressure injection is performed at the timing shown in FIG. The figure shows that the rotation speed of engine 1 and the intake pipe pressure deviate from the set values of 600rPm and -540mmHg, respectively.
This shows the case where the temperature becomes 610rPm and -540mmHg.
On the other hand, according to the embodiment shown in FIG.
Since fuel is measured at the same injection timing and width as Hg, even if the rotation speed is slightly off, as long as it is within the upper and lower limits of the set rotation speed and intake pipe pressure, the rotation speed will increase as in the case of Fig. 7. By holding down the engine 1 and preventing it from descending, the vibration of the engine 1 during idling is made very small, as shown by the chain line in FIG. 8B. That is, in the embodiment shown in FIG. 5, even if the average value deviates somewhat from the idling setting value, stable fuel metering can always be performed in accordance with the average rotation speed.

As described above, this invention uses a constant or averaged frequency of the engine speed instead of the frequency corresponding to the actual engine speed, especially during idling, and a voltage that corresponds to the actual intake pipe pressure. A control unit is provided that outputs a constant or averaged voltage, cancels the control during idling during load operation, and outputs a frequency corresponding to the actual engine speed and a voltage corresponding to the actual intake pipe pressure. By controlling the opening and closing of the electromagnetic valve, the following effects can be achieved.

When the engine is in an idling state and the engine speed and intake pipe pressure fluctuate in a wave-like manner, fluctuations due to increases and decreases in the engine speed can be suppressed and a stable idle speed can be maintained.

In addition, during load operation, the above-mentioned idling control is canceled and the solenoid valve is controlled based on the frequency synchronized with the engine rotation and the voltage corresponding to the pressure in the intake pipe, so that the vehicle can run smoothly. It becomes possible to operate according to performance.

Therefore, during idling, wasteful fuel supply is avoided and the fuel consumption rate is improved, and during load operation, by canceling the injection control during idling, operation is performed without impairing drivability.

[Brief explanation of drawings]

FIG. 1 is an overall longitudinal sectional view of a fuel supply system including an engine, FIG. 2 is a block diagram showing a conventional electronic control circuit, and FIG. 3 is a block diagram showing a control unit of an electronic control circuit according to an embodiment of the present invention. , FIG. 4 is a block diagram showing the injection timing control circuit, FIG. 5 is a block diagram showing another embodiment of the injection timing control circuit, FIG. 6 is a circuit diagram of the injection timing control circuit, and FIGS. The figure is an explanatory diagram showing the injection timing and its effects. 8...Solenoid valve, 10...Electronic control circuit, 12...
...Pressure sensor, 17...Rotation speed sensor, 19
... Waveform shaping circuit, 20 ... Basic calculation circuit, 26
... Control unit, 27 ... Idle switch, 28, 40 ... Injection timing control circuit, 2
9...Pulse frequency switching circuit, 30...Frequency comparison circuit, 31...Switching control circuit, 32...Constant frequency pulse generation circuit, 33...FV conversion circuit, 34,
39...Averaging circuit, 35...VF conversion circuit, 3
6... Voltage switching circuit, 37... Voltage comparison circuit, 3
8... Constant voltage generation circuit.

Claims (1)

[Scope of Claims] 1. Synchronous signal output means for outputting a signal synchronized with the rotation of the internal combustion engine; Load corresponding signal output means for outputting a signal corresponding to the load of the internal combustion engine; and whether the internal combustion engine is in an idle operating state or under load. means for detecting whether the engine is in an operating state; a basic arithmetic circuit that determines the timing of fuel injection into the internal combustion engine and calculates the amount of fuel injection; and a pulse signal generated from the synchronization signal output means, or /V conversion, further averaging, and V/F conversion, and outputting any of the averaged pulse signals obtained by performing V/F conversion to the basic arithmetic circuit, and a load corresponding signal generated from the load corresponding signal output means, or a control unit that outputs to the basic arithmetic circuit one of the averaged load corresponding signals obtained by averaging the averaged values of A fuel supply device comprising a switching circuit that outputs a pulse signal and a load corresponding signal, wherein the basic arithmetic circuit determines fuel injection timing based on an inputted averaged pulse signal or pulse signal.