JP4775199B2 - Air-fuel ratio detection device for internal combustion engine - Google Patents

Description

  The present invention relates to an air-fuel ratio detection apparatus for an internal combustion engine that detects the responsiveness of an air-fuel ratio sensor installed in an exhaust pipe.

  In recent years, in a vehicle equipped with an internal combustion engine, an air-fuel ratio sensor for detecting an air-fuel ratio (A / F) of exhaust gas is installed upstream of a catalyst for exhaust gas purification, and the A / F of exhaust gas is detected using the air-fuel ratio sensor. A technique for calculating the value is considered. The exhaust gas purification efficiency of the catalyst is increased by feedback control of the air-fuel ratio based on the output of the air-fuel ratio sensor. In such an exhaust gas purification system, the response deterioration of the air-fuel ratio sensor is prevented in order to prevent the operation from being continued in a state where the air-fuel ratio control accuracy is lowered due to the deterioration of the response of the air-fuel ratio sensor (that is, the exhaust gas purification efficiency is lowered). There is something to detect.

For example, the technique disclosed in Patent Document 1 includes a sample timing for detecting the air-fuel ratio and a response delay used for detecting the air-fuel ratio in accordance with a deterioration parameter indicating the response deterioration of the air-fuel ratio sensor. Are listed. In the invention of Patent Document 2, the content of calculating the response deterioration of the air-fuel ratio sensor under a specific condition is described.
JP-A-10-73049 Japanese Patent Laid-Open No. 2001-140685

  On the other hand, when the exhaust gas flow rate changes, the responsiveness of the air-fuel ratio sensor changes with the change of the exhaust gas flow rate (see FIG. 4). Here, the responsiveness of the air-fuel ratio sensor is the elapsed time until the air-fuel ratio sensor of the exhaust gas discharged from the cylinder is detected by the air-fuel ratio sensor installed on the upstream side of the catalyst. In FIG. 4, the solid line indicates the response of the air-fuel ratio sensor to the exhaust gas flow rate when the air-fuel ratio sensor is not responsively deteriorated, and the dotted line and the alternate long and short dash line are when the air-fuel ratio sensor is responsively deteriorated. The responsiveness of the air-fuel ratio sensor to the exhaust gas flow rate is shown.

  As shown in FIG. 4, in order to detect the responsiveness of the air-fuel ratio sensor with respect to the change in the exhaust gas flow rate, in the techniques of Patent Documents 1 and 2, the responsiveness of the air-fuel ratio sensor sequentially with respect to the change in the exhaust gas flow rate. It was necessary to detect. Further, even when response deterioration occurs in the air-fuel ratio sensor, it is necessary to sequentially calculate the response of the air-fuel ratio sensor with respect to changes in the exhaust gas flow rate.

  Therefore, in the present invention, there is provided an air-fuel ratio detection device for an internal combustion engine that can estimate the response of the air-fuel ratio sensor to the exhaust gas flow rate without sequentially detecting the response of the air-fuel ratio sensor in accordance with the change of the exhaust gas flow rate. The purpose is to provide.

Therefore, in the invention according to claim 1, air-fuel ratio detection means for detecting the air-fuel ratio of the exhaust gas provided upstream of the catalyst disposed in the exhaust pipe of the internal combustion engine, and air-fuel ratio detection for the change of the air-fuel ratio of the internal combustion engine Based on the air / fuel ratio detection signal of the means, the responsiveness detection for detecting the elapsed time from increasing the fuel injection amount of the cylinder to the calculated air / fuel ratio from the increased amount as the responsiveness of the air / fuel ratio detection means And an exhaust gas flow rate detecting means for detecting the exhaust gas flow rate discharged from the internal combustion engine, and the responsiveness of the air / fuel ratio detecting means detected by the responsiveness detecting means and the responsiveness of the air / fuel ratio detecting means are detected. Based on the exhaust gas flow rate detected by the exhaust gas flow rate detection means, an approximate expression for calculating the responsiveness of the air fuel ratio detection means is calculated, and the responsiveness of the air fuel ratio detection means changes with respect to the exhaust gas flow rate. Not to do And calculating a deviation (hereinafter referred to as “offset”) between the responsiveness of the air-fuel ratio detecting means detected by the responsiveness detecting means and the responsiveness of the reference air-fuel ratio detecting means at the beginning of use. An approximate expression is calculated on the basis of the exhaust gas flow rate in the range where the responsiveness of the air-fuel ratio detecting means changes with respect to the exhaust gas flow rate and the responsiveness of the air-fuel ratio detecting means detected by the responsiveness detecting means.

As described above, the responsiveness of the air-fuel ratio detection unit to the exhaust gas flow rate is determined based on the response from the change of the air-fuel ratio of the internal combustion engine until the air-fuel ratio detection unit detects the change of the air-fuel ratio and the exhaust gas flow rate. By calculating the approximate expression to be calculated and calculating the responsiveness of the air-fuel ratio detection means with respect to the exhaust gas flow rate based on the approximate expression, it is possible to detect the responsiveness of the air-fuel ratio detection means sequentially due to changes in the exhaust gas flow rate. It becomes possible to calculate the responsiveness of the air-fuel ratio detecting means.
In addition, as described above, the responsiveness of the air-fuel ratio detecting means detected by the responsiveness detecting means within the range in which the responsiveness of the air-fuel ratio detecting means does not change with respect to the exhaust gas flow rate, and the responsiveness of the reference air-fuel ratio detecting means. By calculating an offset that is a deviation from the responsiveness at the beginning of use, and calculating an approximate expression for calculating the responsiveness of the air-fuel ratio detection means to the exhaust gas flow rate based on the offset, due to causes such as deterioration Even when the responsiveness of the air-fuel ratio detection to the exhaust gas flow rate changes, the responsiveness of the air-fuel ratio detection means can be calculated.
Further, an approximate expression is calculated based on the offset, the exhaust gas flow rate in the range where the responsiveness of the air-fuel ratio detecting means changes with respect to the exhaust gas flow rate, and the responsiveness of the air-fuel ratio detecting means detected by the responsiveness detecting means. Therefore, it is possible to calculate an approximate expression for calculating the responsiveness of the air-fuel ratio detection means with respect to the change in the exhaust gas flow rate.

Further, as in the invention according to claim 2, when the responsiveness of the air-fuel ratio detection means to at least two different exhaust gas flow rates is compared and the deviation is less than a predetermined value, It is better to judge that the responsiveness does not change.

Further, as in the invention according to claim 3, when the responsiveness of the air-fuel ratio detecting means is larger by a predetermined amount than the responsiveness of the air-fuel ratio detecting means in a range where the responsiveness of the air-fuel ratio detecting means to the exhaust gas flow rate does not change. It is preferable to determine that the responsiveness of the air-fuel ratio detection means changes with respect to the exhaust gas flow rate.

Further, as in the invention according to claim 4 , the air-fuel ratio detection timing may be corrected based on the responsiveness of the air-fuel ratio detection means calculated based on the approximate expression. Thus, by correcting the air-fuel ratio detection timing based on the responsiveness of the air-fuel ratio detection means calculated based on the approximate expression for calculating the responsiveness of the air-fuel ratio detection means with respect to the exhaust gas flow rate, for example, Even when a response delay occurs due to a cause such as deterioration of the fuel ratio detection means, the air fuel ratio can be detected with high accuracy.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a schematic diagram of an engine control system that employs an air-fuel ratio control apparatus for an internal combustion engine according to the present invention. In FIG. 1, an electronic control unit (hereinafter referred to as “ECU”) 30 controls each part of an internal combustion engine (hereinafter referred to as “engine”) 11. The intake system of the engine 11 of this embodiment includes an intake pipe 12, an air cleaner 13, a throttle valve 15, and a surge tank 17. The intake air sucked through the air cleaner 13 is sucked into the engine 11 through the throttle valve 15 and the surge tank 17. The amount of intake air taken into the engine 11 is controlled by adjusting the opening of the throttle valve 15 based on a detection signal from an accelerator sensor 27 provided on an accelerator pedal (not shown). Adjustment of the opening degree of the throttle valve 15 is performed by the ECU 30. Specifically, the ECU 30 outputs a control duty to the throttle motor 16 in order to drive the throttle valve 15 based on a signal from the accelerator opening sensor 27. Based on the detection signal from the crank angle sensor 25 for detecting the engine speed, the detection signal from the air flow meter 14, and the detection signal from the intake pressure sensor 18 attached to the surge tank 17, the intake air is converted into the intake air. In order to supply an appropriate fuel injection amount to the engine 11, a drive signal is supplied to the injector 20. As a result, the optimal air-fuel mixture is supplied into the cylinder 20 of the engine 11, and the air-fuel mixture is combusted by causing the spark plug 18 to execute spark ignition at a desired timing.

The exhaust system of the engine 11 includes an exhaust pipe 22, an air-fuel ratio sensor 23, and a three-way catalyst 24. The exhaust gas discharged from the engine 11 is purified by a three-way catalyst 24 installed in the exhaust pipe 22. More specifically, when the exhaust gas discharged by the engine 11 passes through the three-way catalyst 24, HC is a harmful substance in the exhaust gas, CO, oxidation-reduction reaction of the NO _x to occur, hydrogen, nitrogen, steam, dioxide Carbon is produced. Thereby, purification of harmful substances in the exhaust gas is performed. Further, the control of the throttle valve 15 that adjusts the intake air amount and the injector 19 that adjusts the fuel injection amount is executed so that the air-fuel ratio detected by the air-fuel ratio sensor 23 becomes the target air-fuel ratio.

  A cooling water temperature sensor 26 for detecting the cooling water temperature and the crank angle sensor 25 described above are attached to the cylinder block of the engine 11. The crank angle sensor 25 outputs a pulse signal every time the crankshaft of the engine 11 rotates by a predetermined crank angle, and detects the crank angle and the engine rotation speed based on this signal. The vehicle speed is detected by a vehicle speed sensor 25.

  In this embodiment, the air-fuel ratio sensor responsiveness to the exhaust gas flow rate can be calculated by executing the air-fuel ratio detection routines shown in FIGS. Here, the responsiveness of the air-fuel ratio sensor is the elapsed time until the air-fuel ratio sensor of the exhaust gas discharged from the cylinder is detected by the air-fuel ratio sensor installed in the exhaust pipe. The responsiveness of this air-fuel ratio sensor changes with changes in the exhaust gas flow rate (see FIG. 4). More specifically, as shown in the reference of FIG. 4 and the response of the air-fuel ratio sensor (solid line), the response of the air-fuel ratio sensor with respect to the exhaust gas flow rate increases the response of the air-fuel ratio sensor as the exhaust gas flow rate changes. It can be divided into a changing range (region 1) and a range (region 2) where the responsiveness of the air-fuel ratio sensor does not change much even if the exhaust gas flow rate changes.

  In the present embodiment, the responsiveness of the air-fuel ratio sensor between the range in which the responsiveness of the air-fuel ratio sensor changes greatly and the range in which the responsiveness of the air-fuel ratio sensor does not change much even when the exhaust gas flow rate changes, An approximate expression for calculating the responsiveness of the air-fuel ratio sensor is calculated using the exhaust gas flow rate as a parameter. The flowchart shown in FIG. 2 calculates the responsiveness of the air-fuel ratio sensor using the exhaust gas flow rate as a parameter based on the responsiveness of the air-fuel ratio sensor in a range where the responsiveness of the air-fuel ratio sensor does not change much even if the exhaust gas flow rate changes. An offset (difference) that is one of the constants of the approximate expression is calculated. The flowchart shown in FIG. 3 calculates an approximate expression for calculating the responsiveness of the air-fuel ratio sensor with the exhaust gas flow rate as a parameter, using the offset calculated in FIG. These routines are executed every predetermined crank angle (every 100 ms).

  First, when the routine of FIG. 2 is executed, it is determined in step 10 (hereinafter referred to as “S10”) whether or not the air-fuel ratio sensor responsiveness detection condition is satisfied. Here, the response detection condition of the air-fuel ratio sensor is a case where there is little disturbance with respect to the air-fuel ratio. For example, as described in Patent Document 2, when the vapor concentration learning value is equal to or smaller than a predetermined value, the immediately preceding wall surface adhesion amount correction value is equal to or smaller than the predetermined value, and the cooling water temperature is equal to or larger than the predetermined value, etc. The responsiveness of the air-fuel ratio sensor may be detected under conditions where there is little air-fuel ratio fluctuation due to factors other than the air-fuel ratio variation. Alternatively, it is determined whether the amount of intake air is less than a predetermined value, whether the engine speed is within a predetermined range, whether the engine load is within a predetermined range, and whether the engine coolant temperature is higher than a predetermined value. Thus, the responsiveness of the air-fuel ratio sensor may be detected when the engine operating state is steady. If it is determined in S10 that the air-fuel ratio sensor responsiveness detection condition is satisfied, the process proceeds to S11. If it is determined in S10 that the air-fuel ratio sensor response detection condition is not satisfied, this routine is terminated.

  Next, in S11, the response from the response of the air-fuel ratio sensor (for example, the response of the air-fuel ratio sensor detected at the beginning of use) is used as a reference when there is no response delay due to response deterioration of the air-fuel ratio sensor or the like. It is determined whether an offset (difference) has been calculated. If it is determined in S11 that the offset from the responsiveness of the reference air-fuel ratio sensor has not been calculated, the process proceeds to S12, and thereafter, the responsiveness of the air-fuel ratio sensor to the exhaust gas flow rate is detected. If it is determined in S11 that an offset from the reference value has been detected, this routine is terminated.

  Next, in S12 to S13, the exhaust gas flow rate exga is read, and the responsiveness reg (exga) of the air-fuel ratio sensor with respect to the exhaust gas flow rate exga is detected. As a method for calculating the exhaust gas flow rate, for example, it may be calculated from an intake air amount calculated based on a detection signal from an air flow meter or a detection signal from an intake pressure sensor attached to a surge tank. Further, the exhaust gas flow rate may be calculated based on the calculated intake air amount and exhaust gas temperature. The exhaust gas temperature can be estimated by the following equation.

Exhaust gas temperature = Water temperature at startup + F (ignition timing, integrated exhaust gas flow rate) (Formula 1)
The start-up water temperature of this type is the engine coolant temperature. Further, F (ignition timing, integrated exhaust gas flow rate) is a value calculated using the ignition timing and the integrated exhaust gas amount from the starting time as parameters. As a method for detecting the exhaust gas temperature, an exhaust gas temperature sensor may be installed in the exhaust pipe and detected directly.

  The responsiveness reg (exga) of the air-fuel ratio sensor is obtained by, for example, increasing the fuel injection amount of all the cylinders when the air-fuel ratio of the air-fuel ratio sensor installed in the exhaust pipe is constant. The elapsed time until the air-fuel ratio calculated from the increased amount is obtained. In this embodiment, the response of the air-fuel ratio sensor when the exhaust gas flow rate is read is detected. However, the response of the air-fuel ratio sensor may be read first to calculate the exhaust gas flow rate at that time.

  If the responsiveness reg (exga) of the air-fuel ratio sensor with respect to the exhaust gas flow rate exga is detected in S12 to S13, the process proceeds to S14, and the responsiveness of the air-fuel ratio sensor at the exhaust gas flow rate different from the exhaust gas flow rate when the responsiveness was previously detected has been detected. It is determined whether or not. If it is determined in S14 that the responsiveness of the air-fuel ratio sensor at different exhaust gas flow rates has been detected, the process proceeds to S15. If it is determined in S14 that the responsiveness of the air-fuel ratio sensor at different exhaust gas flow rates has not been detected, the responsiveness of the air-fuel ratio sensor to the exhaust gas flow rates detected in S12 to S13 is stored, and this routine is terminated. .

  In S15, the responsiveness of the air-fuel ratio sensor detected at different exhaust gas flow rates is compared, and it is determined whether or not the deviation is smaller than a predetermined value. Hereinafter, for comparison, the responsivity of the air-fuel ratio sensor with respect to the exhaust gas flow rate detected under one condition is referred to as res (exga1), and the responsivity of the air-fuel ratio sensor with respect to the exhaust gas flow rate detected under the other condition is referred to as res ( exga2). In S15, it is determined using (Equation 2) whether or not the deviation between the two responsiveness values is less than a predetermined value.

| Res (exga1) −res (exga2) | <α (Expression 2)
If it is determined in S15 that the deviation between the two responsiveness is smaller than the predetermined value α, the process proceeds to S16, and the responsiveness of the reference air-fuel ratio sensor is subtracted from the responsiveness of the air-fuel ratio sensor detected under these conditions. The calculated value is calculated as an offset. If it is determined in S15 that (Equation 2) is not satisfied, this routine is terminated.

  In S16, the offset Resofst is calculated using the following equation.

Offset Resofst = res (exga1) −reference value (formula 3)
In the above formula, responsiveness res (exga1) to the exhaust gas flow rate exga1 is used, but responsiveness res (exga2) to the exhaust gas flow rate exga2 may be used. When the offset is calculated in S16, this routine is terminated.

  Next, a flowchart for calculating an approximate expression for calculating the responsiveness of the air-fuel ratio sensor using the exhaust gas flow rate as a parameter will be described with reference to FIG.

  When the routine of FIG. 3 is executed, it is determined in S20 whether or not the air-fuel ratio sensor responsiveness detection condition is satisfied. The air-fuel ratio sensor responsiveness detection condition is when the disturbance to the air-fuel ratio is small, or when the engine operating state is steady, as in the flowchart of FIG. If it is determined in S20 that the air-fuel ratio sensor responsiveness detection condition is satisfied, the process proceeds to S21. If it is determined in S20 that the air-fuel ratio sensor response detection condition is not satisfied, this routine is terminated.

  Next, in S21, it is determined whether or not an offset from the responsiveness of the reference air-fuel ratio sensor is detected. If it is determined in S21 that the detection of the offset from the responsiveness of the reference air-fuel ratio sensor has been completed, the process proceeds to S22, and thereafter, a measure for detecting the responsiveness of the air-fuel ratio sensor to the exhaust gas flow rate is performed. If it is determined in S21 that no offset from the responsiveness of the reference air-fuel ratio sensor has been detected, this routine is terminated.

  Next, in S22 to S23, the exhaust gas flow rate exga is read, and the responsiveness reg (exga) of the air-fuel ratio sensor with respect to the exhaust gas flow rate exga is detected. A method for detecting the exhaust gas flow rate exga and the responsiveness reg (exga) is omitted (see S12 to S13 in FIG. 2).

  When the response reg (exga) of the air-fuel ratio sensor to the exhaust gas flow rate exga is detected in S22 to S23, the process proceeds to S24, and the response of the air-fuel ratio sensor is detected at an exhaust gas flow rate different from the response of the air-fuel ratio sensor already detected. Judge whether or not. If it is determined in S24 that the responsiveness of the air-fuel ratio sensor at different exhaust gas flow rates has been detected, the process proceeds to S25. If it is determined in S24 that the responsiveness of the air-fuel ratio sensor at different exhaust gas flow rates has not been detected, the exhaust gas flow rate exga and responsiveness reg (exga) detected in S22 to S23 are stored, and this routine is terminated. To do.

  In S25 to S26, as shown in the following formulas, is the responsiveness to the exhaust gas flow rate detected under each condition larger by a predetermined value than the value obtained by adding the offset resetset calculated in the routine of FIG. 2 and the reference value? Judge whether or not. For comparison, responsiveness to the exhaust gas flow rate detected under one condition is referred to as res (exga3), and responsiveness to the exhaust gas flow rate detected under the other condition is referred to as res (exga4).

| Res (exga (i))-(resofset + reference value) |> β (Formula 4)
i = 3,4. If it is determined in S25 to S26 that the condition is satisfied,
Proceeding to S27, an approximate expression of responsivity res (exga) of the air-fuel ratio sensor with respect to the change in the exhaust gas flow rate is calculated. If it is determined in S25 to S26 that the condition is not satisfied, this routine is terminated.

  In S27, the responsiveness res (exga3) and res (exga4) of the air-fuel ratio sensor with respect to the exhaust gas flow rates exga3 and exga4 are substituted into the following (Equation 5), a constant A is calculated, and the air-fuel ratio sensor with respect to the exhaust gas flow rate is calculated. An approximate expression of responsiveness res (exga) is calculated.

Responsiveness res (exga) = A / exga + (resofst + reference value) (Formula 5)
The reference value is calculated in advance so that the exhaust gas flow rate is used as a parameter. When an approximate expression of the responsivity res (exga) of the air-fuel ratio sensor with respect to the change in the exhaust gas flow rate is calculated, this routine ends. In this embodiment, it is determined whether the response to the exhaust gas flow rate detected under two different conditions satisfies the condition of (Expression 4), and the constant A of the approximate expression is calculated. It is good also considering the conditions to satisfy | fill at least 1 place or more.

  As described above, in the present embodiment, even when the exhaust gas flow rate is changed by the approximate expression for calculating the responsiveness of the air-fuel ratio sensor using the exhaust gas flow rate as a parameter, the air-fuel ratio is sequentially calculated without calculating the responsiveness of the air-fuel ratio sensor. It becomes possible to calculate the response of the sensor. Further, as shown by the dotted line and the alternate long and short dash line in FIG. 4, the response of the air-fuel ratio sensor can be calculated even when a response delay occurs due to the response deterioration of the air-fuel ratio sensor. In other words, when there is a map of the response of the air-fuel ratio sensor to the exhaust gas flow rate as in the prior art, if the response delay occurs due to the response deterioration of the air-fuel ratio sensor, the response of the air-fuel ratio sensor to the exhaust gas flow rate is sequentially increased. It was necessary to detect and correct the map. However, as in the present embodiment, by using an approximate expression for calculating the responsiveness of the air-fuel ratio sensor using the exhaust gas flow rate as a parameter, the air-fuel ratio sensor is sequentially detected without detecting the responsiveness to the exhaust gas flow rate. It becomes possible to calculate the response of the fuel ratio sensor. More specifically, by substituting the exhaust gas flow rate exga into an approximate expression (Equation 5) for calculating the responsiveness of the air fuel ratio sensor with the exhaust gas flow rate as a parameter, the responsivity res (exga) of the air fuel ratio sensor with respect to the exhaust gas flow rate. Can be calculated.

  Further, for example, the air-fuel ratio detection timing at the time of performing the air-fuel ratio feedback control may be corrected using the air-fuel ratio sensor response calculated using the approximate expression for calculating the air-fuel ratio sensor response. This makes it possible to accurately detect the air-fuel ratio even when the responsiveness of the air-fuel ratio sensor changes due to a change in the exhaust gas flow rate or when the responsiveness deteriorates due to deterioration of the air-fuel ratio sensor, etc. When air-fuel ratio feedback control is performed, exhaust gas can be purified efficiently.

It is a block diagram of the air fuel ratio detection apparatus which concerns on this invention. It is a flowchart which detects the offset from a reference value. It is a flowchart which calculates the approximate expression of the responsiveness of the air fuel ratio sensor with respect to exhaust gas flow volume. It is a graph which shows the responsiveness characteristic with respect to exhaust gas flow volume.

Explanation of symbols

11 Engine 19 Injector 23 Air-fuel ratio sensor 24 Three-way catalyst 25 Crank angle sensor

Claims (4)

An air-fuel ratio detecting means provided upstream of the catalyst disposed in the exhaust pipe of the internal combustion engine for detecting the air-fuel ratio of the exhaust gas;
Based on the air-fuel ratio detection signal of the air-fuel ratio detection means with respect to the change in the air-fuel ratio of the internal combustion engine, an elapsed time from increasing the fuel injection amount of the cylinder to the calculated air-fuel ratio from the increased amount, Responsiveness detecting means for detecting responsiveness of the air-fuel ratio detecting means;
An exhaust gas flow rate detecting means for detecting the exhaust gas flow rate discharged from the internal combustion engine,
Based on the responsiveness of the air-fuel ratio detection means detected by the responsiveness detection means and the exhaust gas flow rate detected by the exhaust gas flow rate detection means when the responsiveness of the air-fuel ratio detection means is detected, Calculate an approximate expression for calculating the responsiveness of the air-fuel ratio detection means ,
The responsiveness of the air-fuel ratio detecting means detected by the responsiveness detecting means within a range in which the responsiveness of the air-fuel ratio detecting means does not change with respect to the exhaust gas flow rate, and the air-fuel ratio at the beginning of use as a reference A deviation from the responsiveness of the detection means (hereinafter referred to as “offset”) is calculated, and the exhaust gas flow rate in the range where the responsiveness of the air-fuel ratio detection means changes with respect to the offset and the exhaust gas flow rate, and the An air-fuel ratio detection apparatus for an internal combustion engine , wherein the approximate expression is calculated based on the responsiveness of the air-fuel ratio detection means detected by the responsiveness detection means . Comparing the responsiveness of the air-fuel ratio detection means to at least two different exhaust gas flow rates, and determining that the responsiveness of the air-fuel ratio detection means to the exhaust gas flow rate does not change when the deviation is less than a predetermined value. 2. An air-fuel ratio detection apparatus for an internal combustion engine according to claim 1, wherein: When the responsiveness of the air-fuel ratio detecting means is larger by a predetermined amount than the responsiveness of the air-fuel ratio detecting means in a range where the responsiveness of the air-fuel ratio detecting means to the exhaust gas flow rate does not change, The air-fuel ratio detection apparatus for an internal combustion engine according to claim 1 or 2, wherein it is determined that the responsiveness of the air-fuel ratio detection means is in a range that changes . Based on the response of the air-fuel ratio detecting means which is calculated on the basis of the approximate expression, an empty internal combustion engine according to any one claims 1 to 3, characterized in that to correct the detection timing of the air-fuel ratio Fuel ratio detection device .

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