JPS6213747A - Fuel feed shut-off device of internal-combustion engine - Google Patents

Abstract

PURPOSE:To prevent production of a fluctuation in an engine output and a fluctuation in a shaft torque, by a method wherein, by means of the discriminating result of each discriminating means and the number of revolutions of an engine from a number of revolutions detecting means, a fuel shut-off means is driven and controlled. CONSTITUTION:A throttle switch 2 discriminates whether the opening of a throttle valve is below a given value or not. A clutch switch 4 discriminates whether a clutch is engaged or disengaged. A neutral switch 3 discriminates whether a transmission gear position is neutral or not. A step-on discriminating circuit 20 is additionally provided for serving as a means discriminating a fluctuation in the opening of a valve resulting from step-on from a fluctuation in the opening of a valve resulting from step-on made according to a driver's will through monitoring of movement of a throttle valve 10. An ECC control unit 15, serving as a control means, also inputs a signal, indicating the discriminating result of the step-on discriminating circuit 20, to decide fuel cut and a releasing condition to drive and control a slow cut solenoid 6 serving as a fuel cut means.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a fuel supply cutoff device that cuts off the supply of fuel to a combustion chamber of an internal combustion engine such as an automobile when the engine decelerates from a high speed.

[Conventional technology]

Hydrocarbons (HC) emitted by internal combustion engines such as automobiles
) In order to reduce the amount of harmful gases such as (Refer to the published "Familia Maintenance Manual").

And, as such a conventional fuel supply cutoff device,
For example, there is one shown in FIG.

To explain this, 1 is an ignition switch, and power is supplied from the battery 7 to the ignition coil etc. through this switch.

Reference numeral 2 denotes a throttle inch as a means for determining the throttle valve state, and it is ON when the accelerator pedal is depressed and the throttle valve is open, and when the accelerator pedal is released and the throttle valve opening is below a predetermined value. It turns OFF when this happens.

Reference numeral 3 denotes a neutral switch as a neutral determining means, which is turned on when the gear position of the transmission is in neutral, and turned off when the gear position is other than neutral.

Reference numeral 4 designates a clutch switch as means for determining clutch engagement/disengagement, which is turned on when the clutch is disengaged and turned off when the clutch is engaged.

5 is an electronically controlled carburetor control unit (hereinafter referred to as "rECC control unit"); 6 is a slow-cut solenoid that is driven and controlled by the output of this FCC control unit 5 to be deenergized or energized; A slow cut valve (not shown) provided in the fuel passage is opened and closed to cut off the supply of fuel by the slow system (hereinafter referred to as "fuel cut J") when energized.

The FCC control unit 5 includes a throttle switch 2. Neutral switch 3. In addition to being connected to the clutch switch 4, it is also connected to the ignition coil.The reason is that the engine speed is detected from the ignition coil's primary circuit intermittent signal, and each switch 2.3
．． 4 ON.

This is because the engine speed information as well as the OFF information is used as information for determining the fuel cut condition.

Now, the fuel cut conditions for such a conventional fuel supply cutoff device are as shown in Table 1.

This is expressed in logic diagrams in FIGS. 7(A) and 7(B).

Note that there is a hysteresis relationship between the engine speed (N) and the fuel cut condition as shown in FIG. 8(A). That is, when the engine speed is low, the fuel is not cut, but when the engine speed is 215 rpm or more, the fuel is cut. , rotation speed is 215
When descending from a value of 0rpm or more, 200Or
Fuel cut continues until pm, and stops when the temperature drops below that.

FIG. 8(B) shows the change in engine speed (N) over time (1) and the corresponding fuel cut state.

Table 1 Conventional fuel cut conditions On the other hand, the relationship between the opening degree of the throttle valve in the carburetor and the ON/OFF state of the throttle switch 2 has a hysteresis relationship as shown in FIG. 9(A).

When the throttle valve opening is smaller than 7.5 degrees, the throttle switch 2 is OFF, but when it becomes larger, it is turned ON. Also, if it closes from a value of 7.5 degrees or higher,
It stays on until 7 degrees and turns off when it goes below that.
become. The width of this hysteresis is determined by constraints imposed by the mechanical structure and is relatively narrow.

Figure 9 (B) shows the change in throttle valve opening over time (1) and the corresponding ON/OFF of throttle switch 2.
Indicates the condition.

[Problem that the invention seeks to solve]

However, in such conventional fuel supply cutoff devices (fuel cut devices) for internal combustion engines, the ON/OFF state of the throttle switch is used as information to determine whether to cut the fuel or not, and the throttle switch is simply The structure consists of mechanical contacts and has little hysteresis, so when decelerating, especially under driving conditions such as continuous descent, the driver presses the accelerator ever so slightly to maintain the vehicle speed, and as a result, the throttle valve opening changes to the throttle switch. When the ON/FF switching opening degree 2 is maintained near 1 (e.g. 7° to 7.5'' as shown in Fig. 9), the slow cut solenoid 6 deenergizes (cuts the fuel) and energizes. Repeat the cycle (without cutting the fuel).

This causes problems such as fluctuations in engine output (P i ) or shaft torque, as well as poor drivability due to jerky vibrations of the vehicle and undulations in the feeling of deceleration.

In addition, in such a coasting state, combustion is slow due to low charging effect, and if the fuel cut is inadvertently released and fuel is supplied, unburned hydrocarbons (HC) will be discharged and the catalyst temperature will rise accordingly. There was also the problem that it led to an increase in

Here, the reason why the slow cut solenoid repeatedly deenergizes and energizes under the above-mentioned operating conditions will be explained.

Under such driving conditions, the clutch is of course engaged and the transmission gear is not in neutral, so both clutch switch 4 and neutral switch 3 in FIG. 6 are OFF. Also, since the vehicle is running to maintain its speed, the engine speed is 2150.
rpI is 11 or higher.

Under these conditions, as is clear from Table 1 and FIG. 7, whether or not to cut the fuel depends on whether the throttle switch 2 is OFF or ON.

However, even if the driver keeps the accelerator constant, the throttle valve itself vibrates by a small angle. Therefore, when the throttle valve opening degree is maintained near the ON/OFF switching angle of the throttle switch 2, this vibration causes the throttle switch 2 to turn to OFF regardless of the driver's intention.
It may turn N or turn OFF.

This operating situation is shown in FIG. FIG. 10(a) shows changes in the opening degree of the throttle valve. First, when decelerating, the opening degree is reduced,
The throttle switch 2 is maintained near the ON/OFF switching opening. However, even in this state, the opening degree fluctuates slightly due to the vibration of the throttle valve itself.

In the figure, the fluctuations are somewhat exaggerated in order to make the explanation easier to understand. Thereafter, when the accelerator is depressed to enter another operating state, the throttle valve opening is increased.

In response to such changes in the throttle valve opening, the throttle switch 2 is turned ON-OFF as shown in FIG. 10(b).
As the steps are repeated, the slow cut solenoid 6 is also changed to the same figure (c
), the process of cutting (de-energizing) and covering (energizing) is repeated.

The present invention aims to solve the various problems described above caused by such phenomena.

[Means for solving problems]

Therefore, the fuel supply cutoff device for an internal combustion engine according to the present invention is designed to prevent fuel cut-off from being performed or released due to vibration of the throttle valve itself. In addition to the condition of the throttle valve, the state of the clutch, and the engine rotation speed, the control means uses the above-mentioned depression discrimination means to determine whether the throttle valve moves when the throttle valve moves in the case of the throttle valve or from other movements. Based on the determination result, the fuel cut and release conditions are determined and the fuel cutoff means (fuel cut solenoid) is driven and controlled.

〔Example〕

Embodiments of the present invention will be described below based on the drawings.

FIG. 1 is a system configuration diagram showing an embodiment of the present invention. The difference from the conventional system shown in FIG. A depressing determination circuit 20 is added as a means for determining whether the valve opening degree changes due to the driver's will and the driver's will, and the FCC control unit 15, which is a control means, generates a signal indicating the determination result of the depressing determination circuit 20. Also enter
Determine the fuel cut and its release conditions.

The point is that the slow cut solenoid 6, which is the fuel cutoff means, is driven and controlled.

Note that 11 is a potentiometer, and 12 is a carburetor. The potentiometer 11 outputs a voltage corresponding to the opening degree of the throttle valve 10, and inputs the voltage signal to the depression determination circuit 20. The rest of the configuration is the same as that of the conventional example shown in FIG. 6, so a description thereof will be omitted.

The operating conditions of this fuel cut device are as shown in Table 2.

Table 2 Fuel cut conditions according to the present invention Comparing these with the operating conditions of the conventional device (Table 1), the operating conditions for "cutting" the fuel and the operating conditions "not" for the fuel cut are the same, but the operating conditions for "cutting the fuel" are the same. The difference is that the operating conditions for "cut release" are stipulated.

In other words, once the cut is started, it will not be canceled unless this "cut cancellation" condition is met.

Figure 3 illustrates the operating conditions in Table 2.
After starting fuel cut under conditions (A), (C
) To move to a state where the fuel is not cut under the conditions,
The fuel cut must be canceled under the condition (B).

Next, an example of the configuration of the depression determination circuit 20 is shown in FIG.

The voltage signal from potentiometer 11 is input to the 2-input terminal IN
is first input to the differentiating circuit 21.

This differentiating circuit 21 is configured by, for example, a combination of a first differentiating circuit 211, a comparator 212, and a second differentiating circuit 213.

The outputs of the differentiating circuit 21 are sent to waveform shaping circuits 22 and 24 using comparators, respectively. The output of the waveform shaping circuit 22 is sent to the monostable multivibrator 25 via the 1 inversion/clamping circuit 23, and the waveform shaping circuit 24 is sent to the monostable multivibrator 25.
The output of the above monostable multivibrator 25 and one more
The signal is sent to two monostable multivibrators 26 and triggers them.

The monostable multivibrator 25 can be cleared, and is cleared by the output from the inverting/clamping circuit 23 to return to its original state. The monostable multivibrator 26 is
Once triggered, a pulse has started to be output, but if the next trigger is input before the pulse of a predetermined width has been output, a new pulse of the predetermined width will start to be output starting from that point, which is what is called a re-output. It is a triggerable monostable multivibrator.

The output of this monostable multivibrator 26 is
Sent to monostable multivibrator 27.

The output and the output of the monostable multivibrator 25 are A
The input signal is input to an ND circuit 28, and an AND operation is performed, and the output of the AND circuit 28 is sent to the FCC control unit as the output of the depression determination circuit 20 shown in FIG.

Next, the operation of the depression determination circuit 20 configured as described above will be explained. As for the operating state, consider the same situation as in the explanation of the prior art.

That is, during deceleration, especially under driving conditions such as continuous descent, the driver depresses the accelerator only slightly in an attempt to maintain the vehicle speed, and as a result, the throttle valve opening changes from the 0N-OFF switching position of the throttle switch 2. Around 7° to 7.5°
This is an operating situation that includes a state in which the vehicle is maintained in the vicinity (see FIG. 9).

FIG. 4 is a waveform diagram for explaining the operation of the depression determination circuit 20, and (a) shows changes in the opening degree of the throttle valve.

When you release the accelerator and decelerate, the throttle valve opening is reduced,
Although the opening is maintained near the ON/OFF switching opening of the throttle switch 2 shown in FIG. 1, the opening varies slightly due to the vibration of the throttle valve itself. Thereby.

The throttle switch 2 is turned ON as shown in FIG. 4(b).
・Repeat OFF. Thereafter, when the accelerator is depressed to enter another operating state, the opening of the throttle valve is increased.

As mentioned above, the output voltage of the potentiometer 11 is set to be a voltage corresponding to the opening degree of the throttle valve, and therefore changes substantially in the same way as the opening degree of the throttle valve changes.

Therefore, the output of the first differentiating circuit 211 in the differentiating circuit 21 of FIG. 2 to which this voltage signal is input is as shown in FIG. 4(c). And comparator 212
If we use a device in which the output is inverted depending on whether the input is positive or negative, the output will be as shown in Fig. 4(d). When this is differentiated by the second differentiator 213, as shown in the figure (e), a positive pulse is generated at the valley of the waveform in the figure (,).
A pulse output that becomes a negative pulse is obtained at the peak.

The time constant of this differentiating circuit 21 is the first-order waveform shaping circuit 22.
Considering matching with 24, it is preferable to set it to about the shortest vibration period of the throttle valve.

The waveform shaping circuit 24 adjusts the output pulses in FIG. 4 (f
) Outputs a positive rectangular pulse as shown in (). On the other hand, the waveform shaping circuit 22 outputs a positive rectangular pulse as shown in FIG. 3(g) only during the period when the negative pulse in FIG. 2(e) is below level B.

In this case, the values of levels A and B are determined by how the roots of the positive and negative pulses shown in FIG. The width of the shaped pulse may be determined as appropriate, taking into account the width of the pulse that is required in order not to interfere with the operation of the next-stage circuit.

The output of the waveform shaping circuit 22 is inverted by 1 by the inversion/clamp circuit 23 and clamped to, for example, Ov to 5V.

Note that the clamp circuit may be omitted if it is possible to obtain a pulse of sufficient size to operate the next stage circuit simply by inversion.

Monostable multivibrator 26 is triggered by the output of waveform shaping circuit 24. Its output pulse width τ! teeth,
Make it approximately equal to the vibration period of the throttle valve.

The reason for this is that once the monostable multivibrator 26 is triggered by the trough of the fluctuation in the throttle valve opening, this fluctuation is suspected to be due to the vibration of the throttle valve, and the vibration remains unchanged for at least one period of the vibration. I looked at it and thought, ``There is a step-in.''
This is to avoid issuing a discrimination signal.

If it was caused by vibration, there would definitely be a peak before the next trough and the monostable multivibrator 25 would be cleared, so we would determine that it was vibration. .

As shown in FIG. 4(i), this monostable multivibrator 26 is re-triggered if the next trigger pulse comes before the output pulse with width τ1 has finished, and from there a new output pulse with width τl is generated. begins to appear. This is to ensure that the situation is always checked only during the period τ1 from the latest trough.

The monostable multivibrator 27 is triggered by the falling edge of the output pulse of the monostable multivibrator 26 and outputs a pulse as shown in FIG. Since this is the output signal width of the discrimination circuit, the width is set to the time required for the judgment by the FCC control unit 5.

The monostable multivibrator 25 is triggered by the output of the waveform shaping circuit 24 (FIG. 4(f)), cleared by the output of the inverting/clamping circuit 2!1 (FIG. 4(h)), and is As shown in (k), a rectangular pulse is output that is triggered at the trough of the waveform in (a) of the same figure and cleared at the peak.

The pulse width τ3 when the clear signal does not come from the inversion/clamp circuit 23 is set as τ3=τi+τ2. here,
The reason why τ2 is added is to perform an AND with the pulse in FIG. 4(j). When a pulse with a pulse width of 3 is completely output, starting from the valley of the potentiometer voltage fluctuation, one period of the throttle valve's vibration cycle (τ
1) This means that there were no mountains during this period.

As a result, the fluctuation at that time is not due to vibration,
It is determined that the accident was caused by the driver's will. Therefore, the output pulses of the monostable multivibrators 27 and 26 are ANDed by an AND circuit 28, and a depression determination signal is output.

In the range ``before depressing'' in Fig. 4(a), the throttle valve is only vibrating, so there is always a peak between τ after the trough, but when ``depressing'' In the latter range, even if you wait for 1 minute from the last valley, the peak will not come, so the depression determination signal is output for the first time here, as shown in FIG. 4 (Q).

Therefore, when the throttle switch 2 is turned OFF during deceleration, if the slow cut solenoid 6 is turned OFF by the ECC control unit 15 and is in the fuel cut state, when this signal is input to the ECC control unit 15, The slow cut solenoid 6 is turned ON, the fuel cut state is released, and the fuel cut state is entered. The operating state of this slow cut solenoid 6 is shown in FIG. 4(m).

By controlling the slow cut solenoid 6 in this manner, it is possible to eliminate jerky vibrations of the vehicle.

In this embodiment, as described above, since the state is checked and determined only during the period τl from the point of the valley of the potentiometer voltage, a delay time of τ1 at maximum occurs. Therefore, if τ′1 is set to a large value, the period for determining whether it is vibration or not becomes longer, and although the certainty of the 1 determination result increases, the delay time increases, so the fuel cut state is canceled when the accelerator is depressed. It will take a long time.

Therefore, it is appropriate to set the value of τ1 to be approximately equal to the vibration period of the throttle valve.

FIG. 5 shows an overview of the fuel supply state of the carburetor.

tl indicates the point in time when the accelerator is depressed, and t2 indicates the point in time when the accelerator has been depressed to a certain point and the position has started to be maintained.

In Fig. S (d) and (e), A is the case of the present invention.

B shows the change in the case of the conventional device, and C shows the change in the case without fuel cut. The state of supply from the slow system before time t1 differs between these.

In case C, in which no fuel cut is performed, a large amount of fuel is supplied from the slow system, but in case B, in which the conventional device performs fuel cut, fuel is intermittently supplied in accordance with the vibration of the throttle valve. In case A of the present invention, no water is supplied at all.

The rise of fuel supply from the slow system after the time tl when the accelerator is depressed is delayed by tL in the case of the present invention A than in the case of the conventional device B, and this is due to the above-mentioned reason.

In this embodiment, the differentiating circuit 21 is used to generate pulses at the peaks and valleys of the voltage fluctuation of the potentiometer 11, but it is not necessarily necessary to generate pulses at the peaks and valleys, and pulses may be generated at other locations. You can also do this.

If the installation accuracy of the potentiometer 11 is controlled and the relationship between the throttle valve opening degree and the potentiometer output voltage is clear, the output voltage of the potentiometer should be set to 7 degrees at the throttle valve opening degree, for example.
, 7.5° may be provided at the front stage of the differentiating circuit 21. In this case, a constant voltage obtained from the ECC control unit 15 can be used as the voltage supplied to the potentiometer 11.

〔Effect of the invention〕

As explained above, the fuel supply cutoff device for an internal combustion engine according to the present invention includes a depression determination circuit that determines whether or not fluctuations in throttle valve opening are caused by the driver's will. The fuel cutoff and release conditions are determined based on the connection/disconnection state, transmission position, engine speed, and the result of the depression determination, and the fuel cutoff means is driven and controlled. This eliminates the need to repeatedly cut and release the fuel, and prevents fluctuations in engine output and shaft torque caused by throttle valve vibration.

Therefore, even under driving conditions such as continuous descent during deceleration, the vehicle will not vibrate or the deceleration feeling will be undulating, improving drivability.

Further, since the fuel cut is not canceled indiscriminately in the coasting state where combustion is slow, the amount of unburned hydrocarbons (HC) discharged is reduced accordingly, and a rise in catalyst temperature due to this can be prevented.

[Brief explanation of the drawing]

FIG. 1 is a system configuration diagram showing an embodiment of the present invention. 2 is a block diagram showing the details of the depression determination circuit 20 in FIG. 1, FIG. 3 is a logic diagram of the fuel cut operation in the present invention, and FIG. 4 is for explaining the operation of the depression determination circuit in FIG. 2. Figure 5 is a diagram showing the fuel supply status of the carburetor, Figure 6 is a system configuration diagram showing an example of a conventional fuel supply cutoff device for an internal combustion engine, and Figure 7 is the same. Logic diagram of the fuel cut operation. Figure 8 is an operation characteristic diagram showing the relationship between engine speed and fuel cut operation. Figure 9 is the throttle valve opening and throttle switch ON/O.
FIG. 10 is a signal waveform diagram for explaining the operation of the conventional example shown in FIG. 6. 1...Ignition switch 2...Throttle switch (throttle valve state determination means) 3
...Neutral switch (neutral discrimination means) 4...Clutch switch (clutch connection/disconnection discrimination means) 6
...Slow cut solenoid (fuel cutoff means) 7...
・Battery 10... Throttle valve 11...
Potentiometer 12...Carburetor 15...
・ECC control unit (control means) 20...
Depression discrimination circuit (depression determination means) Fig. 3 (B) (C) Fig. 4 (ml 7., ":',, OFF N Fig. 5 t+ Lz → ) Figure 8 Figure 9 □ Throttle valve opening Figure 10 □ t

Claims (1)

[Scope of Claims] 1. Throttle valve state determining means for determining whether the throttle valve opening is below a predetermined value, clutch engagement/disengagement determining means for determining whether the clutch is disengaged or engaged, and whether the transmission gear position is neutral. a neutral determination means for determining whether or not the throttle valve is opened; a rotation speed detection means for detecting the engine rotation speed; and a depression determination means for determining whether or not the throttle valve opening degree has changed due to the driver's will. a fuel supply cutoff means for cutting off the supply of fuel to the combustion chamber; each determination result of the throttle valve state determination means, the clutch engagement/disengagement determination means, the neutral determination means, and the depression determination means;
A fuel for an internal combustion engine, characterized in that the fuel for an internal combustion engine is provided with a control means for determining a condition for fuel cutoff and release thereof based on the engine rotational speed detected by the rotational speed detection means and for driving and controlling the fuel cutoff means. Supply cutoff device.