JPH03175129A - Device for diagnosing air-fuel ratio controller - Google Patents

Abstract

PURPOSE:To enhance the accuracy of diagnosis by forcibly shifting an air-fuel ratio control point by a predetermined value so that the position at which the output of a downstream side O2 sensor is suddenly changed is controlled to the position where a predetermined rate of catalytic conversion is achieved. CONSTITUTION:In e.g. an engine lighter in car weight than standard engines and having a relatively large capacity of catalyst, air-fuel ratio is forcibly shifted to rich side by a forcibly shifting means 42B when a judging means 41 judges that the engine is in a predetermined operating condition. As the amount of fuel supplied to the engine is increased by this shift to the rich side, O2 in the exhaust gas is decreased and the O2 storage effect of catalyst is lowered. The position at which the number of inversion of the output of a second O2 sensor 40 (downstream side O2 sensor) is suddenly changed is therefore shifted in the direction in which the rate of catalytic conversion becomes larger, and is settled in a position where a predetermined value of the rate of catalytic conversion is achieved. In an engine heavier in car weight than standard engines and having a relatively small capacity of catalyst, air-fuel ratio is shifted to the lean side.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a diagnostic device for an engine air-fuel ratio control device, and particularly to a diagnostic device for diagnosing the performance of a catalytic converter.

(Prior technology) Oxygen sensors (0
There is a device with a so-called Google 02 sensor system (2 sensors), and a device for diagnosing the catalytic converter has been proposed for such devices (
(See Japanese Patent Application Laid-Open No. 63-97852).

This will be explained using diagram tj49. The diagram is a routine for determining performance deterioration of the catalytic converter, which is performed every predetermined time opening (for example, every 4!118). In S21, the engine rotation speed is within a predetermined range (1000 rpm-≦Ne
≦3000 rpm) In S22, the engine load equivalent amount (@large air amount Qa/rotation loss Ne) is within a predetermined range (0.5Z/rev≦Qa/Ne≦1.0!/
rev) is set to 0. In other words, the process proceeds to S23 only when the engine is in a steady state excluding idle states, acceleration/deceleration states, fuel increase ranges, etc.

At 823, the counter value CT of the timer is incremented by 1, and it is determined whether the predetermined time CToX4msJi has elapsed based on whether 5241 CT≦CTo.

If before the predetermined time has elapsed (CT≦c'ro), S25,
Proceeding to 826, the number of inversions of the downstream WIAO2 sensor output is counted by a counter. That is, in S25, downstream (
Check whether the lIl102 sensor output is reversed or not. If it is reversed, the counter value C8 will be 1 for each reversal at 82G.
Increment by nine.

When the predetermined time elapses in S24 (CT > CT Q),
Proceed to S27. In S27, it is checked whether the counter value (the number of inversions of the downstream 02 sensor) C8 is greater than or equal to a predetermined value C8o, and if cs<cs (, then it is determined that there is no performance deterioration in the catalytic converter. The process advances to 828. In S28, the alarm is stopped (or canceled).

On the other hand, if C8≧C8o, it is determined that performance has deteriorated, and the process proceeds to S30, where an alarm is sounded.

In S32, both counter values CT and C3 are cleared.

When there is no performance deterioration in the catalytic converter, the upstream 02 sensor output has a high response speed (frequency), whereas the downstream 11102 sensor output has a low response speed. However, when performance deterioration occurs in the catalytic converter, the effect of the catalyst storing 02 (02 Strano effect) decreases, so the response speed of the downstream 02 sensor output increases. According to the routine shown in FIG. 9, it is diagnosed that performance has deteriorated when the response speed of the downstream 02 sensor becomes high.

(9, M to be solved by the invention) By the way, if the catalytic conversion rate (especially the conversion rate for HC) drops to about half (for example, 50%) under predetermined operating conditions, this can be considered as performance deterioration of the catalytic converter. and 111
In some countries, the law requires that the information be displayed on the diagnostic monitor. In order to comply with the laws of these countries, the number of inversions of the output of the downstream O2 sensor needs to suddenly change (indicated by the - dotted chain line) at the position where the catalyst conversion rate is 50% in FIG. 10.

In FIG. 10, "Rr-02 reversal number" is an abbreviation for the reversal number of the downstream side 02 sensor output, and "JFr-02 reversal number" is an abbreviation for the reversal number of the upstream side 02 sensor output (first
(Same in Figure 1).

However, in the conventional example, due to differences in vehicle weight, vehicle speed, etc., the downstream position (where the number of reversals of the IllIO2 sensor suddenly changes) deviates from the 50% catalyst conversion rate, as shown by the solid line in FIG.

For example, an engine with medium vehicle weight and medium catalyst capacity (
This engine is the standard engine), whereas an engine with a lighter vehicle weight and a relatively larger catalyst capacity has a smaller gas volume than the standard engine, so
Even if performance deterioration occurs to the same extent as the standard engine, there is sufficient catalyst capacity, so the position where the downstream 02 sensor's number of reversals suddenly changes shifts to a catalyst conversion rate smaller than 50%. Conversely, in an engine that is heavier than a standard engine and has a relatively small catalyst capacity, the catalyst conversion rate will deviate to a value greater than 50%.

In this case, the number of reversals at the position of - point MM was slightly smaller than the predetermined value, and therefore it was determined that no performance deterioration had occurred, but due to the increase in vehicle speed, the position of the sudden change appears to be When the catalyst conversion rate shifts to the smaller side, the number of inversions exceeds a predetermined value, and in this case, it is determined that performance has deteriorated. In other words, although the performance deterioration is at the same level, different vehicle speeds result in different determination results.

Furthermore, in Japanese Patent Application Laid-open No. 63-97845, the upstream side 02
In order to compensate for variations in sensor output characteristics, etc., air-fuel ratio feedback control is performed by the downstream 02 sensor in addition to air-fuel ratio feedback control by the upstream 02 sensor. jM
As the control point increases and the control point becomes an almost perfect three-dimensional point, in such a device, as shown in Fig. 11, the position where the number of reverses of the downstream 02 sensor suddenly changes is determined by the vehicle weight and vehicle speed. Regardless of the catalytic conversion rate, the conversion rate will be higher than 50%.

In Japanese Patent Application Laid-Open No. 64-45913, performance deterioration of a catalytic converter is diagnosed using a wide range air-fuel ratio sensor, but the sensor is expensive, resulting in an increase in cost.

This invention was made by paying attention to such conventional problems, and it is possible to force the air-fuel ratio control point so that the position where the output of the downstream side 02 sensor suddenly changes is controlled to the position where the WIICie conversion rate is a predetermined value. By shifting by a predetermined value,
It is an object of the present invention to provide a device designed to improve diagnostic accuracy.

(Means for Solving the Problems) As shown in FIG. 1, the present invention includes sensors 31 and 32 that respectively detect engine load (for example, intake air IQa) and rotational speed Ne, and means 33 for calculating the basic injection ff1Tp, an oxygen sensor 34 which is installed in the exhaust passage upstream of the catalytic converter and has a characteristic of rapidly changing after the stoichiometric air-fuel ratio, and a slice level S/ corresponding to the stoichiometric air-fuel ratio between the sensor output and the oxygen sensor 34. Means 35 for determining whether the air-fuel ratio has been reversed by comparison with I-, and calculating a feedback correction amount a of the air-fuel ratio so that the air-fuel ratio is controlled to be near the stoichiometric air-fuel ratio in accordance with this determination result. Means 3
6, means 37 for determining the fuel injection amount Ti by correcting the basic injection amount T1 with this air-fuel ratio feedback correction amount α, and means 38 for outputting this injection amount T1 to the fuel injection device 39. In the air-fuel ratio control device for an engine, a second oxygen sensor 4 is installed in the exhaust passage downstream of the catalytic converter and has a characteristic of rapidly changing after the stoichiometric air-fuel ratio.
0 and means 4 for determining whether the predetermined operating conditions are met.
1, the second oxygen sensor output is controlled by the air-fuel ratio feedback correction amount α so that the output of the second oxygen sensor suddenly changes at a predetermined catalyst conversion rate (for example, 50%) when it is determined that the predetermined operating condition is met. Means for forcibly shifting the air-fuel ratio by a predetermined amount (for example, air-fuel ratio feedback correction amount α
Means 42A for increasing/decreasing the proportional, integral, or differential component or advancing/delaying the signal of the air-fuel ratio feedback correction amount by a predetermined time, or means 42B for increasing or decreasing the slice level S/L; The second oxygen sensor output per predetermined time that changes due to the shift
means 43 for measuring (for example, the number of reversals, amplitude, or average value of the oxygen sensor output), means 44 for determining whether performance deterioration has occurred in the catalytic converter based on 1α in this measurement, and outputting the determination result. A means 45 is provided.

(Function) For example, in an engine that is lighter in vehicle weight than a standard engine and has a relatively large catalyst capacity, when a predetermined operating condition is satisfied, the controlled air-fuel ratio is forcibly shifted to the rich side.

As the amount of fuel supplied to the engine increases due to this rich shift, the amount of 02 in the exhaust gas decreases, reducing the 02 storage effect of the catalyst. Therefore, the position where the number of reversals of the downstream side 02 sensor output suddenly changes shifts to the direction where the catalytic conversion rate increases, and settles at a position where the catalytic conversion rate is a predetermined value.

Conversely, for an engine that is heavier than a standard engine and has a relatively small catalyst capacity, the control air-fuel ratio is adjusted by a predetermined value.

Due to this lean shift F, the position where the number of reversals of the downstream side 02 sensor output changes suddenly shifts to the direction where the catalyst conversion rate becomes smaller, and in this case also settles at a position where the catalyst conversion rate is a predetermined value.

(Example) ! @2 Figure is a system diagram of one embodiment.

In the figure, intake air is introduced into the air cleaner 2 through an intake pipe 3, and fuel is injected from an injector (fuel injection device e) 4 toward an intake boat of an engine 1 based on an injection signal from a control unit 20. be done. The combustion gas in the combustion chamber is introduced into a catalytic converter 6 through an exhaust pipe 5, where harmful components (Co, HC, NOx) in the combustion gas are purified by a three-way catalyst and discharged.

The intake air type flow rate Qa is detected by a hot wire type air meter 70, and the flow rate is controlled by a six intake throttle valve 8 which is linked with an accelerator pedal.

The rotational speed Ne of the engine 1 is detected by a crank angle sensor 10, and the cooling water temperature Tw of the engine jacket is detected by a water temperature sensor 11.

Oxygen sensors 12A and 12B provided in the exhaust pipes upstream and downstream of the catalytic converter 6, respectively, have the characteristic of rapidly changing at the stoichiometric air-fuel ratio, and the oxygen sensors 12A and 12B are arranged in the exhaust pipes upstream and downstream of the catalytic converter 6. Detects so-called binary values.

Further, the fully closed position of the throttle valve 8 is detected by the throttle or the switch 9.

Above air 70-meter 7. Crank angle sensor 10, water temperature sensor 11. Outputs from oxygen sensors 12A and 12B are input to control unit 20.

The control unit 20 performs feedback control of the air-fuel ratio, diagnoses performance deterioration of the catalytic converter, and displays the diagnosis results on a diagnostic monitor 21 provided, for example, in the driver's seat.

Nao, control unit 2011% 1 figure means 33
．． 35-38. Has all the functions as 41-45, CP
It consists of U, ROM, RAM and I10 board. The CPU reads the necessary external data from the I10 boat according to the program written in the R and OM, and processes the values necessary for fuel injection control while exchanging data with the RAM. , and outputs the processed data to the I10 boat as necessary.

Signals from various sensors and switches are input to the I10 port, and injection signals are output from the I10 boat. The I10 boat functions as the output means 38 in FIG.

The ROM stores calculation programs for the CPU, and the RAM stores data used in calculations in the form of tables, maps, etc.

FIG. 3 shows a routine for diagnosing performance deterioration of the catalytic converter, which is executed, for example, in synchronization with a timer. mt may be executed at every predetermined rotation angle.

Sl is a part that performs the function of the predetermined operating condition determining means 4 shown in FIG. 1. Here, it is checked whether the predetermined operating conditions are met, and if so, the process proceeds to S2. Considering this, if the predetermined operating conditions are not met, the process proceeds to S175113, and the counter value CFI and the value FLAG 1 of 7 lags are returned to "0".

The predetermined operating conditions for Sl are determined in accordance with regulatory conditions such as laws. For example, if the standard condition is a steady state in which the 02 sensor output is stable, the output Qn of the air 70-meter 7 must be within a predetermined range, and the crank angle sensor 10 must be within a predetermined range.
The engine rotational speed Ne detected by This is a case where all conditions such as the output being equal to or greater than a predetermined value are satisfied.

In S2, the value of FLAG 1 is checked, and if it is 'O'', it is assumed that the mode is not in performance deterioration judgment mode, that is, immediately after the predetermined operating condition has been established, and the process proceeds to S3.On the other hand, if the value of FLAG 1 is If it is 1'', it is determined that the performance deterioration determination mode is in effect and the process proceeds to S6.

That is, FLAG1=1 indicates that the performance deterioration determination mode is in effect, and FLAG1=0 indicates that the performance deterioration determination mode is not in effect.

S3 is a portion that performs the W1 function of the forced shift means 42A in FIG. here! In order to shift the lI control air-fuel ratio by a predetermined value, the proportional amount PL given immediately after the air-fuel ratio is reversed from rich to rich is determined by the following formula (■) to the predetermined value PLS.
Make it bigger.

PL=PL+PLS...■ Note that in equation (2), PL on the right side is a value calculated based on the upstream 02 sensor output by known air-fuel ratio feedback control. The air-fuel ratio feedback correction coefficient α calculated by the known air-fuel ratio feedback control is the fourth
The periodic waveform shown in the figure (proportional components PR and PI- given immediately after the air-fuel ratio reverses from lean to rich or vice versa, and integrals given while the rich continues or returns) IR, IL), and the magnitude of the value is PR=PL, IR
= IL.

From these proportional and integral components, α is determined by the following formulas 〇 to ■.

(i) Immediately after the air-fuel ratio changes from lean to rich α = α
-PR...■ (11) While rich continues α=α-rR...■ (iii) Immediately after the air-fuel ratio changes from rich to lean α
=α0PL...■ (11) While rich continues a=α+IL...■ Using this a, the final fuel injection pulse width T is determined by the following formula
i is determined.

Ti=TpXCoXα+Ts-■ However, in formula 0, Tp is air 70-meter output Q
Basic injection pulse width determined from a and engine speed Ne,
CO is the sum of 1 and a water temperature increase correction coefficient, etc., and Ts is the ineffective pulse width of the injector 4.

In this known air-fuel ratio feedback control, the air-fuel ratio reversal determining means 35 of FIG. Air-fuel ratio feedback correction amount calculation means 36. The functions of the basic injection amount calculation means 33 and the fuel injection amount determination means 37 are performed.

Since only PL is increased in S3, PL>PR. However, in the above example, this increase in PL is for an engine that is lighter in vehicle weight than the standard engine and has a relatively larger catalyst capacity. The reason for increasing PL in this case is as follows. In such an engine, even if the performance of the catalytic converter is degraded to the same extent as in a standard engine, there is sufficient catalyst capacity, so the downstream 02
The position where the number of reversals of the sensor output suddenly changes is the catalyst conversion rate of 50.
It shifts to the side where the catalyst conversion rate is smaller than the % position. Therefore, if the control air-fuel ratio is shifted to the rich side by a predetermined value, the position where the sudden change occurs will be at the position where the catalyst conversion rate is 50%.

Due to deterioration in the performance of the catalytic converter, the 02 Strano effect of the catalyst decreases, so if the control air-fuel ratio is set to the rich side, the 02 Strano effect decreases as the oxygen concentration in the wandering decreases, increasing the catalytic conversion rate. It can be moved as follows.

In this case, since the increase PLS determines how much the catalyst conversion rate can be increased, the value of PLS is determined here according to the vehicle weight and catalyst capacity.

Note that for an engine that is heavier than a standard engine and has a relatively small catalyst, the proportional amount PR may be increased by a predetermined value PR3.

S4, 6 to 12 are portions that perform the function of measuring means 43 in FIG.

First, in S4, the counter value CFI is set to 1 (incremented by nine).

In S5, the value of FLAG 1 is set to '1''.
As long as the predetermined operating conditions continue, the next time will be 86 from S2.
The program then proceeds to the performance deterioration determination mode. After shifting to this mode, the counter value CFI is incremented by 1 in S6.

Therefore, this counter value represents the elapsed time since the predetermined operating condition was satisfied.

For S7 and 88, the downstream side 02 sensor output (in the figure, "Rr0
2J) and the slice level,
It is checked whether the downstream side 02 sensor output has reversed beyond the stoichiometric air-fuel ratio, and if it has reversed, the counter value 02F is incremented by 1 in S8. This counter value 02F represents the number of times the downstream side 02 sensor output is reversed.

In S9, in the part to check whether monitoring has been performed for a predetermined period, the value of CFI is compared with a predetermined value (constant value) CFO#, and if CFI≧C'FO1$, 11 messages are sent for a predetermined time from the forced shift in S3. I decided that and proceeded to SIO.

5IO-812, 81G is a part that returns each parameter to its original state in order to end the performance deterioration determination mode. SIO
and 312, return the values of CFI and FLAG king to 0", and
In ll, cancel the forced shift that was done in S3 (proportional portion P
(subtract the increment PLS from L).

S i 3 is 8! of the performance deterioration determination means 44 in the elS1 diagram!
This is the part that performs the function, and here 02F counted in S8
Compare the value with a predetermined value (constant value) 02FC#, and find that 02F≧
If it is 02FC$, it is determined that the performance has deteriorated in the catalyst/converter, and the process proceeds to 314. Conversely, if 02F<
02 F If it is C#, proceed to S15 1°S i 4
and S15 is f:1tG of the judgment result output means 45 in the J1 diagram.
It is the part that performs the function. In S14, the diagnostic monitor 21
Outputs a signal to a diagnostic monitor to indicate that a device (e.g., a lamp or buzzer) has degraded in performance. S1
5 outputs a signal to cancel the display on the diagnostic monitor.

At 61 and 6, the value of 02F is returned to "0".

In Section 22, the operation of this example will be explained for an engine that is lighter in vehicle weight than a standard engine and has a relatively larger catalyst capacity.

For such an engine, when a predetermined operating condition (such as a steady state of the engine) is satisfied, the proportional portion PL is increased by a predetermined value PLS. Due to this increase in PL, the air-fuel ratio feedback correction coefficient α changes from the broken line to the solid line in FIG. 4, and the control air-fuel ratio as a whole is shifted to the rich side.

As the amount of fuel supplied to the cylinder increases due to this rich shift, 02 in the exhaust gas decreases and the 02 storage effect of the catalyst decreases, so the position where the number of reversals of the downstream 02 sensor output suddenly changes is the position shown in Figure 10. , it moves to the direction where the catalytic conversion rate increases (gA on the right in the figure) and settles at a position where the catalytic conversion rate is 50%. In other words, even if the engine has an arbitrary vehicle weight or catalyst capacity, by appropriately determining the proportional increase or decrease according to the 311 weight or catalyst capacity, downstream 1!
The output characteristic of the 1lO2 sensor can always be brought to the position where the catalyst conversion rate is 50%, and thus performance deterioration of the catalytic converter can be diagnosed with high accuracy.

In addition, in this example, by predetermining the increment PLS according to the unit weight and catalyst capacity, it is possible to bring the position where the number of reversals of the downstream full O2 sensor output suddenly changes to the position where the catalyst conversion rate is 50%. As shown in Fig. 10, when factors other than unit weight and catalyst capacity, such as vehicle speed and other operating conditions, differ, the position where the catalyst conversion rate suddenly changes is 5.
It deviates from the 0% position again. In other words, downstream side 02
The position where the number of reversals of the sensor output suddenly changes is the catalyst conversion rate of 50.
% position, the accuracy of determining performance deterioration decreases. To deal with this, the value of PLS may be determined in accordance with the vehicle speed so that the position where the sudden change occurs is at the 50% position even if the vehicle speed is different. For example, a PLS map for vehicle speed is prepared in advance.

In the embodiment, it is determined that performance has deteriorated when the number of inversions per predetermined time of the downstream 02 sensor output exceeds a predetermined value. It is also possible to measure not only the number of inversions but also the amplitude or average value of the sensor output, and compare the measured value with a predetermined value to determine performance deterioration.

In addition, in the embodiment, the proportional component is increased or decreased, but the same effect can be achieved by increasing or decreasing the integral or differential, shifting the signal a to advance or delay, or slicing the signal for comparison with the upstream 02 sensor. obtained by shifting the level up or down. Note that by shifting the slice level for comparison of the upstream @02 sensor output etc. up or down, [!] of the forced shift means 42B in FIG. will be fulfilled.

For example, similar to FIG. 4, waveforms when the air-fuel ratio is rich-shifted are shown in FIGS. 5 to 8.

In Fig. 5, the integral IL is increased by a predetermined value, in Fig. 6, the differential is added by a predetermined value, in Fig. 7, the α signal is delayed by a predetermined time, and in Fig. 8, the upstream 'RO2 sensor output The slice level S/L compared with V is lowered by a predetermined value.

Finally, Kono invention 1i [[? The present invention can also be applied to the invention described in Publication No. 63-978459. In this case, the position where the number of reversals of the downstream 02 sensor output suddenly changes is relatively shifted to the right side compared to the case in Fig. 10, as shown in Fig. tI4ii. By intentionally shifting the air-fuel ratio control point from the three-way point by a predetermined amount, in this case as well, the position where the number of reversals of the downstream 02 sensor output suddenly changes can be moved to the position where the catalyst conversion rate is 50%. .

(Effects of the Invention) This invention controls the position where the downstream oxygen sensor output suddenly changes to the position of the catalytic conversion rate determined in advance by regulatory conditions etc. by forcibly shifting the air-fuel ratio control point by a predetermined value. As a result, it is possible to stably and accurately diagnose performance deterioration of the catalytic converter.

[Brief explanation of drawings]

Fig. 1 is a diagram corresponding to claims of this invention, Fig. 142 is a control system diagram of one embodiment, Fig. 3 is a flowchart for explaining the control operation of this embodiment, and Fig. 4 is air-fuel ratio feedback of this embodiment. Waveform diagrams of correction coefficient α, Figures 5 to 8
The figures are waveform diagrams for explaining the effects of other embodiments. FIG. 9 is a flowchart for explaining the operation of the conventional example;
FIG. 11 and FIG. 11 are characteristic diagrams for explaining the operation of the conventional example, respectively. DESCRIPTION OF SYMBOLS 1... Engine, 3... Suction pipe, 4... Injector (fuel injection device), 5... Exhaust pipe, 6... Catalytic converter, 7... Air 70-meter (engine load sensor), 10... Crank angle sensor (engine speed sensor), 11... Water temperature sensor, 12A... Upstream side 02 sensor, 12B... Downstream flA O2 sensor,
20... Control unit), 21... Diagnostic monitor 31... Engine load sensor, 32... Engine speed sensor, 33... Basic injection amount setting means, 3
4... Upstream oxygen sensor, 35... Air-fuel ratio reversal determining means, 36... Air-fuel ratio feedback correction amount calculating means, 37... Fuel injection amount determining means, 38... Output means, 39. ...Fuel injection device, 40...Downstream oxygen sensor, 41...Predetermined operating condition f+ determination means, 42 A, 4
2 B... Forced shift means, 43... Measuring means,
44... Performance deterioration determination means, 45... Judgment result output means.

Claims (1)

[Claims] A sensor that detects the engine load and rotation speed,
means for calculating a basic injection amount according to these detected values;
An oxygen sensor is installed in the exhaust passage upstream of the catalytic converter and has the characteristic of rapidly changing after the stoichiometric air-fuel ratio, and it is determined whether the air-fuel ratio has reversed by comparing the output of this sensor with a slice level equivalent to the stoichiometric air-fuel ratio. means for calculating a feedback correction amount of the air-fuel ratio so that the air-fuel ratio is controlled to be close to the stoichiometric air-fuel ratio according to the determination result; and means for correcting the basic injection amount using the air-fuel ratio feedback correction amount. In the air-fuel ratio control device for an engine, the air-fuel ratio control device is provided in an exhaust passage downstream of the catalytic converter, and includes a means for determining a fuel injection amount using a fuel injection device, and a means for outputting the injection amount to a fuel injection device. a second oxygen sensor having a characteristic of determining whether or not a predetermined operating condition is present; and means for determining whether or not a predetermined operating condition is present; means for forcibly shifting the air-fuel ratio controlled by the air-fuel ratio feedback correction amount by a predetermined amount so that the output suddenly changes;
means for measuring the output of the second oxygen sensor per predetermined time that changes due to this forced shift; means for determining whether performance deterioration has occurred in the catalytic converter based on this measured value; 1. A diagnostic device for an air-fuel ratio control device, comprising: means for outputting an output.