JPS58140449A - Air-fuel ratio controlling method for internal- combustion engine - Google Patents

Abstract

PURPOSE:To prevent deterioration of combustion at the time of deceleration while keeping the specific fuel consumption at the minimum level, by increasing or decreasing the air-fuel ratio of supplied mixture according to the variation of combustion to operate an internal combustion engine at the leanest air-fuel ratio, and stopping control on the air-fuel ratio of supplied mixture at the time of deceleration. CONSTITUTION:A control unit 8 is furnished with output signals of an airflow meter 3, a throttle-opening detector 41 and a torque detector 7, and also a signal relating to the engine speed is supplied from an ignition coil 6. From these signals, the control unit 8 computes and controls the valve opening time of an electromagnetic fuel injection valve 5. The torque detector 7 is bolted to an engine supporting mount 75 and produces an analogue signal proportional to variation in the mechanical engine torque, while the control unit 8 functions to keep the amount of supplied fuel at a level close to the region causing misfiring of an engine according to the torque variation caused by the variation of combustion. However, if engine decelerating condition is detected from the output signal of the throttle-opening detector 41, the above control is stopped and the air-fuel ratio is kept at the reference value.

Description

[Detailed description of the invention] The present invention relates to an air-fuel ratio control method for an internal combustion engine.

In general, as shown in Fig. 1, the exhaust gas components emitted by combustion in the internal combustion engine and the fuel consumption rate q of the internal combustion engine
(II/pm, h) is the air-fuel ratio (II/pm, h) supplied to the internal combustion engine.
It is closely related to A/F).

Recently, in addition to purifying exhaust gas, there has been a demand for reducing the fuel consumption rate of engines from the standpoint of resource conservation. As shown in Figure 1, it is advantageous to operate the internal combustion engine in a lean mixture range O1) in order to simultaneously achieve exhaust gas purification and fuel consumption reduction; however, in the lean mixture range, misfires occur. Due to the occurrence of engine variations,
Considering aging, etc., the engine cannot be operated in the lean mixture range, which is on the edge of the misfire limit, and the engine is used in the stable region of 2t1 at the air-fuel ratio below the misfire limit. At present, this is a problem in achieving exhaust gas purification and resource conservation.

As shown in FIG. 1, the lowest fuel consumption rate is achieved when Isoseki is operated at a lean air-fuel ratio before misfire placement. Combustion fluctuations are related to A/F, and the closer to the misfire area, the sharper the combustion vibrations become. Therefore, since combustion fluctuations in the cylinders appear as vibrations in the engine body due to the torque reaction force generated in each cylinder, we take advantage of the fact that combustion fluctuations in the engine body can be detected by engine vibrations, and calculate engine combustion vibrations from the engine. By controlling the air-fuel ratio supplied to the engine so that the combustion fluctuation remains at a certain value, it is possible to achieve a significant improvement in fuel efficiency by controlling the air-fuel ratio to always be within the misfire range and at the best fuel efficiency point. . In Fig. 1, Δτ (kg・m) represents the torque vibration.

According to the above-mentioned supply air-fuel ratio control, the supply air-fuel ratio to the engine is controlled so that combustion fluctuations are uniformly kept at a constant value even when the engine is in a deceleration state required by the driving vehicle.

However, engine torque is originally zero or negative in the light load range during deceleration, and this signal is different from the m signal that appears due to combustion fluctuations.If this signal is used to control the air-fuel ratio supplied to the engine, the combustion state will change. There are problems such as unburned gas being emitted, poor fuel efficiency, and poor driving feeling.

SUMMARY OF THE INVENTION In view of the above-mentioned problems, an object of the present invention is to obtain the combustion fluctuation of ennon, control the air-fuel ratio supplied to the engine so that the combustion fluctuation of the engine becomes a constant value, and detect the deceleration state of the engine. Based on the concept of canceling the air-fuel ratio increase/decrease control operation that is supplied to the engine and forcibly operating at the standard air-fuel ratio, the air-fuel ratio is always controlled to the air-fuel ratio that is below the misfire range and has the best fuel efficiency, and when the engine decelerates, the combustion The purpose is to prevent the condition from deteriorating and to always maintain good fuel efficiency and exhaust gas while driving.

In the present invention, combustion fluctuations in the internal combustion engine are detected by a combustion fluctuation detector, and a control device increases or decreases the air-fuel ratio supplied to the internal combustion engine in accordance with the detected combustion fluctuations, and when the engine decelerates, the air-fuel ratio supplied to the internal combustion engine increases or decreases. There is provided an air-fuel ratio control method for an internal combustion engine, characterized in that an increase/decrease lid for the cough supply air-fuel ratio is stopped by an increase wrinkle stopping device.

An apparatus for performing an air-fuel ratio control method for an internal combustion engine as an embodiment of the present invention is shown in FIG. In the device shown in FIG. 2, the engine 1 is a spark ignition type engine for driving a car, and the air for combustion passes through an air cleaner 23, an air flow meter 3, an intake conduit 21, and an intake valve 24, and enters the combustion chamber 11 of the engine 1. is inhaled. The suction conduit 21 is provided with a throttle valve 4 that can be operated arbitrarily by the driver.

Fuel is injected and supplied to the intake valve 24 from the electromagnetic fuel injection valve 5 installed in the intake conduit 21. A mixture of fuel and air is combusted in the combustion chamber 11 and is discharged into the atmosphere via the exhaust valve 25 and the exhaust pipe t22. The control unit 8 is a control circuit that calculates the cost of fuel to be supplied to the engine 1 according to the operating state of the engine 1, drives the electromagnetic fuel injection valve 5, and controls the fuel lI + cage supplied to the engine 1. Detection signals from an air flow meter 3 that detects the intake air lid of the engine l, an ignition coil 6, a torque detector 7 that detects the torque drive of the engine l, and a detection signal of a throttle opening degree detector 41 that detects deceleration are input. . In this embodiment, the signal from the air flow meter 3 is used as the intake air cover for the engine 1, but instead of the air flow meter 3, the intake pipe is determined based on the intake pipe negative pressure and engine rotation speed generated downstream of the throttle valve 4 of the engine 1. The ring gear (dis) that rotates in synchronization with the rotation of the ennon l, which moves even when determining the amount of air.
Of course, it is also possible to detect a rotation signal from a J computer or the like and obtain four-turn copying. As shown in Fig. 2, the torque detector 7 is attached by melting to a mount 75 that supports the engine, and detects the Daketai in multiple directions, preferably four or more directions, around the crankshaft in Ennon's lean band. It is detected by a piezo element, etc. distributed to the engine, and an analog signal is obtained in proportion to the mechanical torque fluctuation of the ennon.
Although several sensors are arranged, detection with just one sensor is sufficient.

The torque detector 7 is a pressure sensor 71. It consists of a rubber mount 73 and a rubber mount cover 74, and is attached to the arm 72 in the following order: the pressure sensor 71, the rubber mount cover 74, and the rubber mount 73. Pressure sensor 7
For example, a small plate pressure detector using a piezo element is used. The throttle opening sensor 41 is the throttle opening sensor 41
The potentiometer is structured so that it is linked to the rotation of the shaft, and the output of the potentiometer is output as a linear voltage.

The configuration of the control unit 8 in the device shown in FIG. 2 is shown in FIG. The amplifier 881 has a known configuration consisting of a buffer and an amplifier. Bandpass filter 882
The amplifier 881 extracts only the output having a frequency of I Hz to several Hz from the analog signal from the amplifier 881, and uses, for example, Morle 852 manufactured by Rockland Systems.

The clock circuit 8831 has a known configuration consisting of an oscillation circuit using a crystal resonator and a counter for dividing the frequency of this oscillation circuit.

゛.

The timing pulse generation circuit 800 is a clock circuit 883
Based on the clock from the peak hold circuit 810
reset signal and correction calculation circuit (hereinafter referred to as gcpu)
This is a circuit that generates an interrupt signal to the 886.

The configuration of the timing pulse generation circuit 8oo is shown in FIG. In Fig. 4, the input terminal is 800m.

To 800b, black, 2Hz and 5K from circuit 883
The black and white signals of Hz are respectively input. Input terminal 800
m is connected to the reset terminal R of the counter with divider 801, and the input terminal 800b is connected to the counter with divider 80.
It is connected to the clock terminal CL at 0m. The counter 5oiVi with a divider, for example, CD401 of IC manufactured by RCA
7 is used, and its output Q1 is connected to C through terminal 800e.
Used as a signal for interrupt calculation of PU 886. Outputs Q5 and Q8+-1R-S are connected to set terminal S and reset terminal R of Free, Defro, and Zo 802, respectively, and output Q9 is connected to clock enable terminal CE. It is connected to.

For example, a CD4013 manufactured by RCA IC is used as the R-S free and differential f802, and its output Q is connected to a peak hold circuit 810 via a terminal 800d.

The operation of the timing/arm pulse generation circuit 8oo will be explained with reference to the 12V waveform N1. The 2 Hz .9 pulse shown in FIG. 12 (1) is input to the reset circuit of the counter 801 with a divider, and counting starts when the .9 pulse changes from "1" to 10. A frequency of 5 kHz is input to the clock input of the counter 801. Therefore, when the first .9 pulse comes, the output Q I K-4' pulse is output fL. When the 9th pulse comes, the output Q9 becomes “
Since the clock enable terminal becomes "1" and the clock enable terminal "L", the zero clock stops being manually operated until the next reset. Therefore, as shown in FIG. 12 (2), a malus is outputted to the output Q1. The output/P pulse is terminal 800
The CPU 886 triggers the start of the interrupt calculation by turning on the signal c. Outputs Q5 and Q8 set and reset the R-S flip flop 802 and the R-S flip flop! The /f pulse shown in FIG. 12 (3) is output from the 8020 output Q. The fdl/4 pulse is input to the peak hold circuit 810 via the terminal 800d, has a width of approximately 600 microseconds, and becomes a reset signal for the peak hold circuit.

The configuration of peak hold circuit 810 is shown in FIG.

In FIG. 5, the positive pole of the diode 801 and the negative pole of the diode 811 are connected to the output of the pantonous filter 882, the ji4 pole of the diode 801 is connected to one end of the resistor 802, and the other end of the 0M resistor 802 is connected to the capacitor. 803
and the non-inverting input of the passoa enhancer 806 and the resistor 80
It is connected to 4. The negative electrode of capacitor 803 is grounded. The other end of the resistor 804 is connected to one end of an analog switch 805. The other end of the analog switch 805 is grounded, and the control terminal is connected to No. 11 in FIG. 12(3) of the timing circuit 800. The positive terminal of the diode 811 is connected to a resistor 812.
Connect it to one end. The other end of the resistor 812 is connected to the negative terminal of a capacitor 813, the non-inverting input of a buffer amplifier 816, and a resistor 814.

The positive terminal of capacitor 813 is grounded. The other end of the resistor 814 is connected to one end of an analog switch 815.

The oil leak of the analog switch 815 is grounded, and the control terminal is connected to the timing/base pulse generation circuit 800.
It is connected to the signal shown in FIG. 12 (3). The buffer amplifier 8160 inverting input is connected to the output. The output of buffer amplifier 806 is connected to one end of resistor 822, and the other end is connected to the non-inverting input of buffer amplifier 825 and resistor 821. The other end of the resistor 821 is grounded.

The output of buffer amplifier 816 is connected to one end of resistor 823, and the other end is connected to the inverting input of buffer amplifier 825. The output of buffer amplifier 825 is output terminal 81
Analog-to-digital (A-D) converter 8 via 0c
30 and connected to one leak of resistor 824.

The other end of resistor 824 is connected to the inverting input of buffer amplifier 8250.

The operation of beater hold circuit 810 is described below.

12 (3) from the timing pulse generation circuit 800 to the control inputs of the analog switches 805 and 815.
) is applied, the analog switches 805 and 815 are closed during this 74 pulses, so the charge on the capacitors 803 and 813 is transferred to the resistors 804 and 8 with low resistance.
14, resetting the voltage on capacitors 803 and 813 to zero. Then band pass filter 882
(The output waveform shown in 0812 diagram (4) is the input terminal 810b.
When the voltage enters the capacitor 803 through the diode 801 and the resistor 802, the capacitor 803 is charged to a positive voltage.

After the voltage of this capacitor 803 is reset, a positive peak value is held until the next reset. When the voltage of the capacitor 803 is outputted through the buffer amplifier 806 with high input impedance shown in the table, the 12th
The waveform will be as shown in Figure (5).

On the other hand, the output waveform shown in FIG. 12 (4) is the input terminal 81.
When the voltage enters from 0b, a capacitor 813 is charged to a negative voltage through a diode 811 and a resistor 812. The negative peak value of the rolling pressure of the capacitor 813 is held from the time it is reset until the next time it is reset. #
When the capacitor 8130' voltage is outputted through the next high input impedance buffer amplifier 816, the waveform shown in FIG. 12 (6) is obtained. By taking the difference between the output of the buffer amplifier 806 and the output of the buffer amplifier 816 in the differential amplifier 825, the difference between the positive peak value and the negative peak value from one reset to the next reset is calculated from the differential amplifier 825. The waveform is output as shown in FIG. 12 (7).

Margin below The #It configuration of the A-D conversion circuit 830 is illustrated in FIG.

In FIG. 6, input/output control (Il
o) The signal is directly input to the NAND r-) 883, and is inverted by the INNO-4-ET 835 and input to the ANDF-) 836. CPU886's De 1 Chair Select (SEL
) signal is directly Nando f-) 833 and anddart 8
36. Also, inverter 837 and resistor 838
, a delay circuit is configured by a capacitor 839,
SEt is sent to the tent f-t 836 through this delay circuit.
The i= sign is input.

Thus, the ANDf-) 836 outputs a signal with a width of about lOO nanoseconds as shown in Figure (8) of m12. This Norse signal is a successive approximation type A-D transformer.
It is input manually to the A-D conversion command terminal CNV.

As the A/D converter 831, for example, an ADC80AG-12 manufactured by Braun Co., Ltd. is used. A-D Hentai 583
The conversion end terminal EOC of No. 1 is connected to the busy terminal BUSY of the sleeve booster circuit 886, and the output terminals Bl to B12 are
It is connected to the pass line of the CPU 886 via the state buffer γ832. 3 state puff complete 832Vi
For example, Toshiba's IC Te3012 has been used for a while.

A-Dt subcircuit 830 operation is described above. m1
When the noise signal shown in FIG. 2 (2) is input from the timing noise generation circuit 800 to the CPU 886, the CPU 88
6. The currently running program is interrupted and the A-D conversion processing program is executed. Figure 12 (8) by the rriA-D conversion start command in the program.
The f pulse is applied to the A-D converter input terminal CNV of the A-D converter 831, and the t conversion starts at the rising edge of this pulse. At the same time, the output signal of the conversion end terminal Eoc shown in FIG. 12 (9) rises to the l'' level tζ. Here, the conversion end terminal EOC is connected to the CPU.

88617) 7-", E'mil," =, y
) DCUOe, i@(”Connected to BSY,
Completion of the read command of analog No. 16 from the peak hold low 810 is “O” of the conversion path r terminal EOCO output color code.
The I10 signal and the SEL signal are both held at the "L" level until this time.

Then, the successive approximation type A-Di: decider 831 performs a variable operation while the output signal of the EOC terminal is at the "L" level, and outputs the dinotated two-track data signal from the output terminals Bl to B12. . When the conversion operation is completed, the output signal of the conversion end terminal EOC becomes "0" level and the CPU
The read command state of 886 is released, and the error log signal data from the peak hold circuit 810 is transferred to the CPU 886.
1 is read in.

The configuration of the rotational speed detection circuit 840o is shown in FIG. Is the rotation speed detection circuit 840 A? It is composed of a pulse shaping circuit 840-1 and a counting circuit 840-2. The /4' pulse shaping circuit 840-1 receives the 4 pulses of the negative terminal of the ignition coil 6 from the input terminal 840m, and is connected to one end of the aH resistor 8401. The other end of resistor 8401 is resistor 8402 and capacitor 8
403, and the other end of the capacitor 8403 is grounded. The other end of the resistor 8402 is connected to the anode of a diode 8404, and the cathode of the diode 8404 is connected to a resistor 8405, a capacitor 8406, a Zener diode 8407, and a resistor 8408! I'm here. The other ends of the resistor 8405, capacitor 8406, and Zener diode 8407 are grounded, and the other end of the resistor 8408 is connected to the pace of the transistor 8418.

The emitter e of the transistor 8418 is connected to the ground, and the collector is connected to the resistor 8409 and the Schminowtonand gate 841.
The input source is O.

One end of resistor 8409 and Schmidt Nand gate 841O
The Sen input is +5■rto! V is input.

The output of the Siemit Nandoket 841O is applied as a trigger pulse to a monostable multivibrator 8413 composed of a capacitor 8411 and a resistor 8412, and the output of the cough rate stabilizing multivibrator 8413 is composed of a capacitor 8414 and a resistor 8415. It is input as a trigger pulse to a monostable multivibrator 8416. As the monostable multipigrator 8413.8416, for example, CD4047 manufactured by RCA Corporation is used. In this way, from the output of the monostable multivibrator 8416, the timing and timing of the waveform as shown in Fig. m13 (2) with respect to the signal from the ignition coil 12 in Fig. 8g13 (1) is generated.
A mother pulse signal is output.

Counting circuit 840-2 will be described below.

The 2a counter 8421 counts and frequency-divides the black, red, and false signals inputted to the black, red, and red terminals CL, and uses, for example, a CD4024 manufactured by RCA.

Then, this counter 8421 receives a frequency of approximately 128 kHz as shown in FIG. 13(3).
f132 as shown in Figure 13 (4) by dividing the frequency of the signal.
A frequency divided/main pulse signal of about kHz is output from the output terminal Q2. The counter 8422 with a divider basically counts the clock signals input to the clock terminal CL, and the output signal of one of the output terminals Q2 to Q4 is at the "L" level. And when the "L" level signal is input to the count operation stop terminal EN,
Stop operation.

However, in this embodiment, the output terminal Q4 is connected to the stop terminal EN, and when the output of the output terminal Q4 reaches the "L" level, a "1" level signal is input to the stop terminal EN, and the counting operation is stopped. . In this state /ll susu type circuit 8
40-1 to 4t3 When the timing/base pulse signal shown in Figure (2) K is input to the reset terminal R, the counter 842
2 is reset, and the output of the output terminal Q4 is as shown in Fig. 13 (7
)K shows the Kr0J level. Then, when time T has elapsed and the signal input to the reset terminal R reaches the "0" level, the counter 8422 starts counting, and outputs from the output terminals Q2 and Q3 are respectively shown in FIG. 13 (5).

As shown in (6), Kpl! An L-order/f pulse signal is output. Thereafter, when the output of the output terminal Q4 reaches the "L" level, the counter 8422 stops counting again.

Counters 8421, 8422 and Nolles shaping circuit 84
The output signals of 0-1 are respectively 8423.8
424 to the 12-bit counter 8425;
The Q3 output of the counter 8422 is input to the reset terminal R of the counter 8425.

That is, if we take the NOR logic between the output signal of the 9-Russ shaping circuit 840-1 shown in FIG. 13 (2) and the 93 output of the counter 8422 shown in FIG. 13 (7), we get When the arm pulse signal as shown in FIG. 13 (8) is output, and further the NOR logic between the output signal of this NOR r-) 8423 and the output signal of the counter 8421 shown in FIG. 13 (4) is taken. By Noah r-) 8
424 outputs a signal as shown in FIG. 13 (9), and this signal is input to a counter 8425.

Here, the timing/main pulse signal shown in FIG. 13(2) falls to the rOJ level, and the NOA r-
) 8423 reaches the "L" level, the counter 8425 stops counting. After that, the outputs of the output terminals Ql to Q12 of the counter 8425 are as follows.
The rising edge of the Q2 output of the counter 8422 at time t2 is temporarily held and stored in registers 8426 to 842g (for example, CD4035 manufactured by RCA).

Next, when the Q3 output of the counter 8422 reaches the "L" level at time t3, the counter 8425 is reset, and at the time t4, the Q4 output of the counter 8422 becomes r.
When reaching the lJ level, the counter 8425 starts counting again.

Since this operation of the counter 8425 is repeatedly performed in synchronization with the ignition coil 6 outputting the ignition signal, the output terminals Ql to Q4 of the shift registers 8426 to 8428 output the reciprocal number 1/N of the engine rotation speed N. Two proportional signals are output. 3 state buffer 8430
The output becomes high impedance while the "L" level signal is applied to the control terminal 8431, and the output terminal p840c-n is connected to the CPU 8 through the pass line.
86.

The control terminal 8431 receives the output signal of the Nando f-) 8432, and the Nando goo) 8432 receives the output signal from the CPU 88.
The device control unit that is internally covered by 6.

) (DCU) I10 signal and SEL signal are input. Then, when the output signal of the NAND f-to 8432 reaches the "0" level, a 2-over signal that is compared to l/N of the shift registers 8426 to 8428 is sent to the correction calculation circuit 8432.
86.

The configuration of the intake air amount counting circuit 85G is shown in FIG.

The input terminal 8501 has approximately 1 as shown in FIG. 14 (2).
A clock signal of approximately 28 kHz is input, and a frequency of about 28 kHz is input. S2 and counter with divider 851
CLK is input to the four terminals. The input terminal 850b receives from the fuel amount calculation circuit 887 the p4 pulse of the time Tp compared to the intake air amount (hereinafter referred to as Q/N) per one revolution of the ennon as shown in FIG. 14 (1)K. It is input to the reset terminal R of the NAND dart 852 and the counter with divider 851. As the divider-equipped counter 851, for example, an IC CD4017 manufactured by RCA is used. The divider-equipped counter 851 basically counts the black and shoe pulse signals input to the black and white terminals CL, and the output from one of the output terminals Q2 to Q6 (i is at the rlJ level). No, and count operation stop terminal zNK
When the r l J level signal is input, the operation is stopped.

However, in this embodiment, the output terminal Q6 and the stop terminal EN are connected, and when the output of the output terminal Q6 reaches the rlJ level, an "l" level signal is input to the stop terminal EN, and the counting operation is stopped. In this state, when the error signal shown in FIG. 14 (1) K is input from the fuel amount calculation circuit 887 to the reset terminal R, the counter 851 is reset, and when the input signal reaches the "0" level, the counter 851 is reset. counter 851
starts counting operation, and output terminal Q2. From Q4 onwards, as shown in Figure 14 (4) and (5),
4 pulse signals are output. Thereafter, when the output from the output terminal Q6O reaches the "L" level, the counter 851 stops counting again. The outputs Q2 and Q4 of the counter 851 are respectively output from shift registers 854 to 856 (if RC).
It is input to the black terminal CL of the IC manufactured by Company A (CD4035) and the reset terminal RK of the counter 853. Further, the output of the NAND r-) 852 is inputted to the counter 853's black terminal CLK.

Here, the time Tp proportional to Q/N shown in FIG. 14 (1)
When the 9th pulse is input to the input terminal 850b, the time T,
The blacks and ri of the function are input to the counter 853, and the number of blacks and ri during this period is counted (that is, the time Tp is counted).After that, when the /mother pulse reaches the "0" level at time to, the counter 853 Stop counting operation. Next, at time t1, when the output Q2 of the counter 901 becomes "L" level, the outputs of the output terminals Q1 to Q12 of the counter 903 are temporarily held in the shift registers 854 to 856.

When the output Q4 of the counter 851 reaches the "L" level at time t2, the counter 853 is reset and becomes ready for the next counting operation. Since this counter 8530 operation is repeated in synchronization with the pulse shown in FIG. 14(1), shift registers 854 to 8! A 2-over signal proportional to Q/NK is output from each output terminal Q1 to Q4 of S6 in synchronization with the engine rotation. 3 state batfu 7
857 is a terminal whose output becomes high impedance while a level signal is applied to the control terminal 85, and the output terminal group 850c=n is connected to the CPU via a pass line.
886. The output signal of the Nantes gate 860 is input to the control terminal 859, and the output signal of the Nantes gate 860 is inputted to the control terminal 859.
60 has an I from the DCU built in the CPU886.
10 signal and SEL signal are input. When the output signal of the NAN)'r-)860 reaches the urOJ level, a two-pass signal proportional to the Q/N of the shift registers 854 to 856 is input to the cpυ886.

The margin differentiation circuit 884 is a known circuit that differentiates the analog signal from the throttle opening detector 41 with respect to time and outputs an analog output proportional to the speed of the throttle opening.

Assuming that depressing the throttle 4 is considered acceleration, and depressing the throttle 4 is considered deceleration, when deceleration occurs, the output of the differential gate 884 is proportional to the deceleration, and an electromotive voltage is generated. A comparator 885 is a known circuit that compares a reference voltage corresponding to a constant deceleration with the output voltage of the differentiating circuit 884, and outputs a signal "1" if the voltage is above the reference voltage, and outputs an "o" signal if it is less than the reference voltage.

886KFi microcombi, - For example, a 12-bit microcombi, which can use a tall type.
Toshiba's TLC8-12 system can be used.

The configuration of the digital-to-analog (D-me) conversion circuit 87G is shown in FIG. The D-me conversion circuit 870 has an input Δ
-! $71, Nando r-)872, shift register 87
3 to 875 and D-me converter 876 (e.g.
It consists of a Braun DAC8G). The 1 signal from the CPU 886 is inverted by an inverter 871 and then input to the NAND dart 872, and the 8KL signal is directly input to the NAND dart 872.

Therefore, when a command is issued to output the air-fuel ratio correction value F4 calculated by the CPU B 86 to the DA conversion circuit 870,
When the signal rOJ of Ilo is at the level of the SEL signal (the SEL signal is at the "1" level), the AND r-to 872 outputs a "1" level signal. This "1" level signal is applied to each shift register 8.
73 to 875 are input to the pin terminal CL.

Shift registers 873 to 875 are the same as those used in the rotational speed detection circuit 840, and have black and red terminals C.
When a “1” level signal is input to L, the data input terminal D
Input the signal applied to D4 to ll1L,
The signals are output from output terminals Q1 to Q4. In this way, the two-pass data signal of the air-fuel ratio correction value Fd is input to the input terminals 11 to B12 of the D-'M converter 8760, converted to an analog voltage, and then output from the output terminal OUT.

An analog voltage proportional to the data signal indicating the air-fuel ratio correction value Fd is output from the output terminal OUT.

The fuel amount calculation circuit 887 will be explained below. The circuit 88
7 is a device that has the same function as the four-cylinder engine electronically controlled fuel injection device (hereinafter referred to as EFI) shown in Japanese Patent Application Laid-open No. 49-67016, and the OWK is detected from air flow meter 3.
The human air amount signal and the ignition signal synchronized with the engine crank rotation from the ignition coil 6 are input, and the basic valve opening time Tp (between the engine speeds mentioned above) of the electromagnetic fuel injection valve (hereinafter referred to as the injection valve) is determined. Based on this calculation, nine types of correction calculations are performed depending on the operating state of the engine to determine the opening time of the injection valve O, drive the injection valve 5, and control the amount of fuel supplied to the engine 1.

Here, the CPU 886 calculates the D-m conversion path 87G.
The air-fuel ratio correction value FdFi converted into an analog voltage is corrected using the same method as other correction calculations for the intermittent air temperature and water temperature sections.

The operation of the CPU 8860 is explained by the flowchart in FIG. 10. When a key switch (not shown) is turned on, the power is turned on and the operation starts. In step s1, all memories are cleared to 0, and then in step s2, the initial value of the air-fuel ratio correction value F- is set to 2048.

The center value was set to (12 bits,)-4096. ) ste, rs
Set the master mask in s so that the CPU accepts interrupt calculations, and then enter the standby state for interrupt calculations in step S4).
The state is S4.

After that, time passes and the timing pulse generation circuit 80
0 to O Fig. 12 (2) Interrupt operation is started at the rising edge of the pulse from "0" to "L" - When the interrupt operation is started, step 81? will disable 0 interrupts from now on. Stella!
At 811, generate the /ms in Figure 12 (II), and
At the same time, the mu D conversion 11831u A-D conversion is started using the signal as a trigger, and at the same time, the output from the shame C terminal in Fig. 12 (9
) Nofrus becomes "1" and CPU 886 becomes BU8
When the Y input becomes "1", the operation stops. This is step 812. When the Mu-D converter 831 completes Mu-D conversion, the ZOC terminal output (9) in FIG. 12 becomes "O" and the CPU 886 resumes calculation. When the calculation is restarted, the CPU 11116 reads the torque fluctuation value output from the MuD converter 831 in step 1113.
) The value/variable value is converted and read. At step fm 14, the comparator 8850 output D is read. ) read in step 815 is "1". In the case of NO, the process proceeds to step 816, and in the case of YES, the process proceeds to step 825. This Stella f82s is the ninth one that sets the correction value to O if the throttle deceleration is less than the set value.

In step 1f816, the Q/)JO value counted by the a large air amount counting circuit 850 is read. In step 817, a value l that is inversely proportional to the engine rotational speed counted by the rotational speed detection circuit 850 is read, and by taking the reciprocal of this value, the engine rotational speed N can be determined from K. Here, FIG. 11 shows the peak value Ta of the IO torque fluctuation value when operating at the best fuel efficiency point under each condition as parameters of N and Q/Nt engine operating conditions. It is. This is stored in advance in a read-only memory (hereinafter referred to as ROM).

In step 81g, the read Q/N and N are found on the map shown in FIG. 11, and Ta stored in the #roaring ROMC) address is read out. Ste, Gu819
Then, the magnitude of the above-mentioned im and Tm read in step 813 is determined, and it is determined whether the air-fuel ratio under the current engine operating condition is lower than the best fuel efficiency point or leaner. That is, T
m) If it is Ta, the torque fluctuation is small and the air-fuel ratio is low. Step 1120 is the rich correction O calculation, in which the air-fuel ratio is richly corrected in proportion to the difference between the current torque fluctuation value and the target torque fluctuation value Ta. That is, if the torque fluctuation value is large, the air-fuel ratio is corrected by a large amount, and if the torque fluctuation value is small, the air-fuel ratio is corrected by a factor of five. Step 11°822.823 is the maximum value of the rich correction for the front air fuel.
The ennon is regulated to a maximum value as an air-fuel ratio correction value sufficient to change the combustion range from an unstable combustion range to a stable combustion range. Stella on Ste, Gua26! The current air-fuel ratio correction calculation is calculated by adding the correction values obtained in steps 820, 822, and 823 to the air-fuel ratio correction value Fd obtained in the previous calculation. Stella! S21 is an operation for lean correction of the air-fuel ratio, and the current air-fuel ratio correction value Fd is calculated by subtracting the lean correction value Ft from the previous air-fuel ratio correction value F-. Lean correction value Ft
is determined by considering control stability and responsiveness. In steps 824 and 825, the minimum value of FdC) is set to O so that the air-fuel ratio correction value Fd does not become a negative number due to the calculation in step 821. Step S27 outputs the air-fuel ratio correction value Fd obtained by the above operation to the D-direct conversion circuit 870, permits an interrupt in step 828, and executes Step 8.
Before the interrupt occurred on 29! Return to log tsum depth state.

With the above configuration and operation, 1. ．． The air-fuel ratio supplied to the engine can be controlled to the best fuel efficiency point. Stay 7 of the flowchart in Figure 10
15 shows the relationship between the time passage from 815 to 8271 and the air-fuel ratio correction calculation.
Step 7'8190 in Fig. 10) Shows the results of determining the magnitude of the torque fluctuation, and (3) is the air-fuel ratio correction value FdO.
It shows the result of D-me conversion. The torque fluctuation signal in Fig. 15 (1) is the torque fluctuation peak value T at the best fuel efficiency point.
When a and shi become large, it is determined that the torque fluctuation is large in FIG. 15(2), and the air-fuel ratio correction value Fd in FIG. 1S(3) is rich-corrected (RCH, COR, month).

Lean correction (LN) is applied when other torque fluctuations are small.

COR,).

In this example, the torque fluctuation value at the best fuel efficiency point is, for example, the engine operating condition rotation speed 200 rpm shown in Fig. 1.
, ) torque 4 k#-m is 0.1 kg -wr, and the relationship between the torque fluctuation value lτ and the detection signal 8 (810) obtained from the peak hold (b) path is as shown in Fig. 16. Therefore, the determination level Ta under the engine operating conditions is
(Step 819 of the flowchart in Figure 10) is the output voltage from the peak hold circuit, which is 15V. In the case of lean correction, the correction value Ft for one-time (0.5 seconds) braking was set to 0.015 in terms of air-fuel ratio. This value was determined from experiments in consideration of control stability and responsiveness. On the other hand, when performing chi correction, from the air-fuel ratio at the boundary between the misfire region and the stable combustion region (the air-fuel ratio 2α5 as shown in In Figure 1, in order to correct the air-fuel ratio to 2α0), the per-air O correction value Fa is required once (0.5 seconds).
The maximum value Fm was set to 0.5 in terms of air-fuel ratio. Then, the proportionality constant K was determined so that a one-time air-fuel ratio correction value of 0, s could be obtained from the difference between the torque fluctuation values for the air-fuel ratios of 20.5 and 20.0. (When correcting to the rich side, it is important to quickly correct the air-fuel ratio to the stable combustion range in one correction in order to prevent engine misfires.) In the above-mentioned embodiment, the electronically controlled Using a fuel injection device.

Although the engine is described, the O control is not limited thereto, and the same O control as in 4 can be applied to an engine equipped with an electronically controlled cat leter.

In the above-mentioned embodiment, the O differential value was taken from the throttle opening signal as a means for detecting engine deceleration, but the method is not limited to this, but it is also possible to take the differential value of the engine rotation speed, the intake air amount, or the intake pipe negative pressure. I can do it.

According to the present invention, the air-fuel ratio is always controlled to be the best in terms of fuel efficiency and maximum fuel efficiency, and the combustion condition is prevented from deteriorating when the engine decelerates, thereby always keeping both fuel efficiency and exhaust gas in the best condition. Able to drive.

[Brief explanation of the drawing]

@Figure 1 shows the air-fuel ratio and torque fluctuations of the internal combustion engine, fuel consumption rate,
A characteristic diagram showing the relationship between exhaust gas components; FIG. 2 is a diagram showing a device for performing an air-fuel ratio control method for an internal combustion engine as an embodiment of the present invention; FIG. 3 is a circuit diagram of a control unit in the device shown in FIG. , Fig. 4 is a circuit diagram of the timing pulse generation circuit in the 3-diagram circuit, Fig. 5 is a circuit diagram of the peak hold circuit in the 3-diagram circuit, and Fig. 6 is a circuit diagram of the unevenness conversion circuit in the circuit in Fig. 3. Figure, Figure 7 is #! Figure 8 is a circuit diagram of the rotational speed detection circuit in the circuit shown in Figure 3. Figure 9 is a circuit diagram of the intake air amount counting circuit in the circuit shown in Figure 3. The figure is an operation flowchart showing the operation order in the tI7c3 diagram circuit, FIG. 11 is a diagram showing the map stored in the ROM used in step 81B of the flowchart of FIG. 13, FIGS.
Figure 14 is a waveform diagram explaining the operation of the circuit in Figure 3;
The figure shows the relationship between step 819 and step 827 of the flowchart in Figure 10 and the air-fuel ratio correction calculation, and Figure 16 shows the characteristics that show the relationship between the engine torque fluctuation value and the peak hold circuit output voltage. It is a diagram. 1-internal combustion engine, 11--combustion chamber, 21... suction conduit,
22...Exhaust pipe, 23...Air cleaner, 24
... Intake valve, 25 - Exhaust valve, 3 - Air flow meter, 4 - S4, Tor valve, 41 - Throttle detector, 5 - Electromagnetic fuel injection valve, 6 - Ignition coil, 7...
- Torque detector, 8- Control unit, 800... Timing pulse generation circuit, 81O- Peak hold circuit, 83G- Mu D conversion circuit, 840... Rotation speed detection circuit, SSO- Suction Air volume counting circuit, 870
...D-me conversion circuit, 881-.Amplifier, 882...
・Band pass filter, 883-・Clock lDo path, 8
s4--Differentiating circuit, 885--Comparator, 886...
Correction calculation circuit, 110... D-me conversion circuit, 887.
...Fuel amount calculation circuit. Patent Applicant Japan Auto Parts Research Institute Co., Ltd. Toyota Motor Corporation Patent Application Agent Patent Attorneys Akira Ikuki, Patent Attorney Kazuyuki Nishidate, Patent Attorney Masashi Matsushita, Patent Attorney Akira Yamaguchi Figure 8 950 70 [Page 1] Continuation of 0 Invention Author: Takashi Shigematsu, 1 Toyota-cho, Toyota-shi Toyota Motor Corporation Applicant: Toyota Motor Corporation, 1-Toyota-cho, Toyota-shi

Claims (1)

[Claims] 1. A combustion fluctuation detector detects internal combustion combustion fluctuations, and a control device controls =u according to the detected combustion fluctuations.
[i-pi-nai-t! l! A method for controlling an air-fuel ratio of an internal combustion engine, comprising increasing or decreasing the air-fuel ratio supplied to the engine, and stopping the increase or decrease in the supplied air-fuel ratio using a supply air-fuel ratio increase/decrease lid stop device when the engine is decelerated. 2. Detection of the MA of the internal combustion engine for stopping the increase/decrease of the supplied air-fuel ratio is performed using manifold pressure, throttle opening,
2. The method according to claim 1, wherein the method is carried out based on detection of at least one of intake air amount and engine rotational speed. 3. To detect the deceleration of the internal combustion engine, the analog output of the manifold pressure detector, throttle opening detector, or intake air detector is differentiated by a differentiation circuit, and the differential output capability and the set value are compared by a comparator. A method according to claim 1, carried out by.