JPS58195044A - Air-fuel ratio controlling method - Google Patents

Abstract

PURPOSE:In an air-fuel ratio controller employing O2 sensor, to correct the shift of static air-fuel ratio of integrating information correctly, by modifying the correcting amount to be stored in a non-volatile memory through the difference between the average integrating information and the predetermined intermediate reference. CONSTITUTION:The detected level from O2 sensor 35 is provided to a comparator CP while the decision signal between lean and rich is integrated in a counter CT1 then said level and the level stored in a nonvolatile memory (REG1-REG3) selected in accordance to the suction air are employed to set the numeric value to a frequency divider DIV thus to control the injection time. A counter CT2 provided with the output from the comparator CP will add the count of the counter CT1 to 16 time adder ADD1 every time when the output from the comparator is inverted and to provide the 16 time average value of the maximum and minimum integrating information to a correction arithmetic unit 43. Said unit 43 will correct the content in the memory on the basis of said average value.

Description

Detailed Description of the Invention The present invention verifies the air-fuel ratio based on the exhaust gas components of the internal combustion engine, and uses this detection signal to determine the L of the air-fuel mixture supplied to the internal combustion engine.
The present invention relates to an air-fuel ratio control method that performs feedback control so that the fuel ratio becomes a predetermined value.

An oxygen sensor is usually used as a means for detecting the air-fuel ratio based on exhaust gas components of an internal combustion engine, and the output of the oxygen sensor is compared with a predetermined voltage level, and the direction of integration of the integrator is reversed based on the result of this comparison. A common method is to control the air-fuel ratio by improving the quality of the fuel supplied to the internal combustion engine in proportion to the output of the integrator. In the case of internal combustion engines for automobiles, a fuel-fuel ratio that is slightly richer than the stoichiometric air-fuel ratio is required under high-load operating conditions, and in this case, the oxygen sensor stops controlling the air-fuel ratio. Furthermore, since the normally used oxygen sensor starts to operate normally at temperatures above 350° C., feedback control cannot be performed when the internal combustion engine is cold. However, if feedback control is stopped, there is a possibility that the air-fuel ratio will deviate from the target air-fuel ratio due to errors in the control system. First, as a means to compensate for th, the output of the integrator during feedback control is shifted from the intermediate value of the integrator by a value corresponding to the deviation in the air-fuel ratio, and pre-integration is performed.
A correction amount is calculated from this shift amount, this correction amount is stored in a memory, and the above-mentioned air-fuel ratio at the time of feedback stop is controlled by this stored correction amount, thereby compensating for the deviation in the above-mentioned air-fuel ratio. It is proposed to do so.

As a method of calculating the correction amount from the shift amount from the intermediate value of the output of the integrator, the output of the integrator is sampled at a predetermined interval of 4 m, and the history of the output is greater than or smaller than the intermediate value of the integrator. Depending on the situation, there is a method of increasing or decreasing the above correction amount by a constant value. However, the above integrator output fluctuates in the lean-rich fluctuation period of 02 YANSA during feedback control, and the above shift amount is also stable. It is difficult to accurately detect the 511th shift amount and reflect it in the correction amount depending on the sampling timing.

The present invention has been made in order to solve the above-mentioned problems, and uses the above-mentioned correction value to control the air-fuel ratio even during the above-mentioned feedback control. The correction amount is corrected based on the deviation of the averaged values from the intermediate reference value of the air conditioner, and the shift amount is accurately detected and reflected in the air-fuel ratio.

An embodiment of the present invention shown in the drawings will be described below. 1st
The figure is a configuration diagram of the present invention, in which the intake air of the internal combustion engine (3) passes through the Karman vortex type air 70-sensor. (1
A vortex is generated downstream of 1), and the ultrasonic waves generated by the ultrasonic transmitter (21) undergo frequency modulation every time the vortex is generated, and reach the ultrasonic receiver (22). Vortex detection device (
2) Outputs a signal that generates the above one sound to the ultrasonic transmitter (21), and also demodulates the F' M signal with a built-in signal detected by the ultrasonic receiver e22). The vortex generator (11)
11111:,,,.

It outputs a pulse train with a frequency corresponding to the frequency of the winter Karman vortex that occurs downstream. The frequency of this pulse train is determined by the amount of air passing through the air flow sensor (1), that is, the internal combustion engine (
3) is proportional to the amount of air inhaled. (3) is, for example,
This is an internal combustion engine used in the East, which produces a mixture of air taken in through an intake pipe (36) and fuel supplied from a fuel supply valve (31) installed upstream of a throttle valve (32). Inhale and pre-work.

(32) Adjust the amount of air taken into the internal combustion engine (3) by using the id throttle valve. A fuel pump and a fuel pressure regulator (not shown) are connected to the fuel supply valve (31), and the pressure of the suction f (36) and the fuel supply ff (3
1) The differential pressure with the fuel pressure supplied to the fuel is kept constant (
34) is a water temperature sensor that detects the cooling water temperature of the internal combustion engine (3), and is, for example, a thermistor-like sensor whose resistance increases as the temperature decreases. (35) detects the air-fuel ratio from the oxygen concentration in the exhaust gas of the exhaust pipe (37), and when the air-fuel ratio is smaller than the stoichiometric air-fuel ratio (rich), it is 4 degrees IV, and when it is larger than the stoichiometric air-fuel ratio (lean), it is 0. This is an oxygen sensor that outputs a voltage of about 1v. (4) I″i, vortex detection device (2),
Cooling water temperature sensor (34), oxygen sensor (35), Paki 1
- The amount of fuel supplied to the internal combustion engine (3) is controlled by manually controlling the system switch (38), etc., and controlling the opening time of the fuel supply valve (31) in accordance with the operating state of the internal combustion engine (3). It is a control device. Here, vacuum switch (3
8) (Ii, Throttle valve (32) of intake officer (36)
), and is turned on when the negative pressure of the suction pipe (36) becomes higher than a predetermined value, and turned off otherwise. The control +11 device (4) is the vacuum switch (3
8) is on, the internal combustion engine (3) is in a high load operating state.

FIG. 2 is a diagram showing the configuration of the control device (4).

(42) uses a time width calculation S device to calculate the time to open the fuel supply valve (31) based on signals from the vortex detection device (2), the vacuum switch (38) of the cooling water temperature sensor (34), etc. The digital value corresponding to this time is set as a timer (TM).
). (OsC1) is an oscillator, and the output of the oscillator is frequency-divided by a divider (D) and a timer (TM).
is manually powered. The division ratio of the division device (D-engine V) is controlled by the feed shift! The oxygen sensor (35) is controlled by the No. 11 device (41) according to the temperature of the oxygen sensor (35). -The output of the vortex detection device (2) is 7 rigs and 70 tubes (fI'p') and 1
The frequency is divided by 72 and a trigger signal is output to the timer (TIA). The timer (TM) is triggered by the above trigger (No. 8 is manually operated).
Then, the output is IklJ and the time width performance JIE device (42
), starts counting the output pulses of the divider (DIv), and after counting the above-mentioned digital value, sets the output to rLJ. Driver' (
DR) turns on the fuel supply valve (31) while the output of the timer (TM) is "H".

Here, the output frequency of the vortex detection device (2) is equal to the output frequency of the internal combustion engine (3).
) is proportional to the intake air amount, so as this intake air aversion increases, the number of times the trigger signal is manually input to the timer (rM) increases, and therefore the number of times the fuel supply valve (31) is opened increases. become. If the output pulse width of the timer (TM) is constant, a substantially constant amount of fuel is always supplied to the internal combustion engine (3) with respect to the intake air Kit. In addition, the one-hour width calculation device (42) detects the temperature of the cooling water with a cooling water wetter mister (34), and changes the digital value output to the timer (rM), thereby detecting the temperature of the internal combustion engine (42).
In the cold state 1' of 3), the output pulse width of the timer (Tall) is lengthened to increase the amount of fuel supplied to the C engine (3). The feed puncture system #J device (41) determines the air-fuel ratio of the internal combustion engine (3) based on the oxygen concentration in the exhaust gas of the internal combustion engine (3) detected by the oxygen sensor (35), and sets the air-fuel ratio to the division device (DIv). By changing the value, the period of the basic clock supplied to the timer (TM) is changed. Here, the period of the output pulse of the oscillator (O20l) is τ, the numerical value iM is set in the branching unit (1'V) by the feedback control 111 device (41), and the timer (TM) is set by the time width calculation device (42). The value set to N
Then, the timer (TM) is controlled in accordance with the output of the bird (35). Note that the division device (DIv) is composed of a down counter, counts the output of the oscillator (osc 1 ), and when the count value becomes zero, pre-centres the output value of the feedback control device (41) to the down counter, It's like starting a down count again.

The time width calculation device (42) includes a vacuum switch (37
) is off, the digital a corresponding to the stoichiometric fuel ratio
Set the value to Tie calculation - (TM) and output the FITNO control signal to the 74-DOBACK suppressor (41).Also, when the vacuum switch (37) is on, the stoichiometric air-fuel ratio A digital value such as the following is set in the timer (TM), and a feedback stop signal is output to the feedback control device (41).

FIG. 3 is a diagram showing the configuration of the feedback control device (41). The oscillator (osc2) outputs pulses with a constant period to the counter (c'r1). Comparator (c
p) compares the output voltage of the oxygen sensor (35) with the set voltage, and outputs an rHjt signal if it is lower than 0.5V, and an "L" signal if it is lower. The counter (CTI) is 8
When the internal combustion engine (3) stops, the bit amplifier down counter is set to a value of 128, and when the internal combustion engine (3) stops,
If the width calculation device (42) outputs the above-mentioned feedback stop signal, count! 1gthlrF- is stopped.

After the first dIJ of the internal combustion engine (3), the counter (CTI)
If the output of the converter (CP) is rHJ, the pulse of the oscillator (osc2) is counted down, and if it is rLJ, it is counted up, and the output of the oxygen sensor (35
) is subjected to integral signal processing. Here, the stoppage of the internal combustion engine (3) is detected by, for example, detecting the ignition cycle of the internal combustion engine (3), and if it is equal to or longer than a predetermined cycle, it is determined that the internal combustion engine (3) has stopped.

(Ai)Di) is a 12-bit adder, which becomes zero when the time width arithmetic unit (42) outputs a feedback stop signal, and the count value of the counter (CTI) every time the output of the comparator (cp) is inverted. Add. (CT2) is a 4-pit counter with a time span calculation device (42) of 7
4-When the dopak stop signal is output, it is zero; otherwise, the number of inversions of the comparator (cp) is counted, and the operation is repeated to become zero every time the comparator (cp) rotates 16 times. (?V) is an f-V converter that converts the output frequency of the vortex detection device (2) into voltage f, and (AD) is an A-D converter that converts the output of the f-V converter into digital. . The correction calculator (43) is composed of something like a microcomputer, for example, and it records notes U (i(l!1iGl), (
RlG2) or from the value y1 stored in (RffiG/)! /128 Here, if the stored value y1 is a constant value, the comparator (C
When the output of P) is rLJ, that is, the air-fuel ratio is lean, it is divided by the integral output of the counter (CTl)! (i) Engineering V)
The set value of the fuel supply valve (31) is controlled to increase gradually, and the opening time of the fuel supply valve (31) is controlled to become longer.
When the output of p) is rHJ, that is, when the air-fuel ratio is rich, the valve opening time is controlled in a direction that shortens the valve opening time. Also,
The operation mode is determined based on the amount of intake air by comparing the output value of the AD converter (AD) with a predetermined value in the correction leakage Jl unit (43).

While the feedback control signal is being output, the correction generator (43) controls the controller (cp) every time the count value of the counter (CT2) changes from 15 to OK.
) is inverted 16 times by adding the value of the mother counter (CTI) (the maximum value and the minimum value that is applied to each cycle of the integral output) using the adder (
ADDl) is added to the adder's addition result 2.
and the internal combustion at that time -%, (, , memory selected according to the intake air amount (RzGl), (ngu2), (
values y1 to 271 stored in any of uiti3)
+((Z/16)-128)/4 (assumed to be 2 equations) is calculated, and the result of this equation is stored in the selected memory (updating the stored content). Here, the above y1 and z/
The value corresponding to the correction coefficient 1.0 for the valve opening time of 16 is set to 128, and the center value of the integration process at the exit of comparison 11 (Cf') performed by the counter (CTI) is also 1.
28.

FIG. 4 shows changes in the value of the counter (c'r1) and the value in the memory.弼) indicates the value of the counter (CTI), and (1)) indicates the value of the memory. Internal combustion engine (3)
If the air-fuel ratio of
i, X2, etc., and the average value thereof corresponds to the value for correcting the shift toward the lean side.

Next, when the output of the comparator (c p) rotates 16 times, the value in the memory is corrected according to the above two equations according to the deviation amount between the average value of the integral output and the intermediate value, and the quasi-value. figure(
1)) Then, at time tl, the air-fuel ratio changes to the rich side.

Since the above-mentioned valve opening time is corrected by the above-mentioned equation 1, ) gradually changes around the value 128. In other words, the value stored in the memory corresponds to correcting the deviation of the air-fuel ratio of the internal combustion engine (3) from the stoichiometric air-fuel ratio.

Here, when the above-mentioned feedback stop signal is output, the correction generator (43) I/'i selects one of the memories (Rm, ,)l) to (rtn;u3) according to the intake air amount at that time. and set only the value stored in the memory (ignoring the value due to the integral output) in the frequency divider (D-engine V). Therefore, in this case as well, from the stoichiometric air-fuel ratio of the internal combustion engine (3), The deviation is corrected.

In addition, in the above embodiment, the memory is connected to the control device (
4) A non-volatile memory configured to be supplied with power from a battery (not shown) even if the power supply is cut off.

As is clear from the above explanation, the memory value is determined by the deviation between the average value of the counter (CT1) values 16 times each time the comparator (c P) is inverted and the center value of the counter (c'r1). Since the correction is performed, it is possible to detect a correction amount for a static air-fuel ratio deviation of the integral output without being affected by fluctuations in the integral signal itself, and it is possible to accurately detect an air-fuel ratio deviation. Therefore, the feedback control fal by the oxygen sensor (35)
Since the air-fuel ratio can be controlled using the value stored in the memory even when the & is not performed, the air-fuel ratio can be adjusted appropriately even at normal times or under high load.

In this example, the number of additions for average value calculation is 16.
However, other values are also acceptable.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an embodiment of the present invention, FIG. 2 is a block diagram of the control device (4) in FIG. 1, FIG. 3 is a block diagram of the feedback control 'ill device (41), and FIG. The figure shows the control device (
4) is a timing chart. (1)... Air 70-sensor, (2)... Vortex detection device, (3)... Internal combustion engine, (4)... Control device, (3
1) Fuel supply valve, (32) Throttle valve, (35) Oxygen sensor, (38) Paki 1
- system switch, (41)...feedback control device, (42)...time width calculation device, (uscl), (O
8C2 piece...Oscillator 1, (43)...Correction performance l! m, (
D Engineering V)...Branch unit, (rM)...Timer, (D
H)...Driver, (c p)...Comparator, (CT/ ), (CT2)...Kakuunter, (B
'V),, f-V converter, CAD)-A-D
f conversion II, (Ra)l) ~(R[()3)...memory. Agent Shin Kuzuno -11 '1. ... ,')'・B Figure 1 Figure 1 Procedural Amendment (Original! Iri 1, Indication of Case Patent Application No. 1981-77@81 2, Title of Invention Air Fuel Ratio Control Method 3, Amendment Relationship with the case involving the person who filed the patent application Address of the patent applicant: 2-2-3 Marunouchi, Chiyo III-ku, Tokyo
Title Title (601) Mitsubishi Electric Corporation Representative Hitoshi Katayama Part 4, f (Embedded 6, Claims of the specification subject to amendment, Detailed explanation of the invention, Brief explanation of the polished surface) Contents (1) The "Claims" of the specification are amended as shown in the attached sheet. (2) The specification is amended as follows. Claims: Air-fuel ratio sensor that detects air-fuel ratio based on engine exhaust gas components , and a storage processing step for storing in a non-volatile memory a correction amount corrected based on the integral information obtained in this integral processing step. and the above-mentioned stored correction amount. An air-fuel ratio control method comprising the step of correcting a correction amount stored in the non-volatile generation memory based on a deviation from a predetermined intermediate reference value for integral information.

Claims (1)

[Claims] a storage processing step of storing the output signal of an air-fuel ratio sensor that detects the air-fuel ratio based on the exhaust gas components of the engine in an integral memory; The method includes an average value calculation step of calculating an average value of the integral information subjected to the integral processing, and an average value of the integral information obtained by this average value calculation step and the above integral information. An air-fuel ratio control method comprising the step of correcting a correction amount stored in the non-volatile memory according to a difference between a predetermined intermediate reference value and a predetermined intermediate reference value.