JP5510154B2 - Fuel injection amount correction control method and control apparatus for internal combustion engine - Google Patents

Description

  The present invention relates to a fuel injection amount correction control method and a control apparatus for an internal combustion engine, and more particularly to a method that considers a detection error (sensor deviation) by a sensor or the like.

  In an internal combustion engine, a configuration is known in which a control device instructs a command injection amount to a fuel injection device, and the fuel injection device injects fuel accordingly. A configuration is also known in which learning about the command injection amount is performed in accordance with the actual fuel injection amount. For example, the configuration is such that the injection amount correction value for the command injection amount is learned based on the deviation between the actual air-fuel ratio detected by the A / F sensor and the target air-fuel ratio calculated from the intake air amount and the command injection amount. is there. An example of such a configuration is disclosed in Patent Document 1.

JP 2001-241348 A

However, the conventional technique has a problem in that appropriate correction control cannot be performed when a detection error occurs due to variations due to individual differences or deterioration of sensors.
For example, in the configuration of Patent Document 1, even when a detection error occurs in the A / F output detection unit and a value different from the actual value is detected, the injection amount is based on the detection value including the detection error. Therefore, the optimum correction amount cannot be obtained.

  The present invention has been made to solve such problems, and it is an object of the present invention to provide a method and apparatus for appropriately performing correction control in accordance with the detection error of a sensor.

The method for controlling learning according to the present invention calculates an air-fuel ratio deviation based on the actual air-fuel ratio detected by the air-fuel ratio detection means and the target air-fuel ratio, and when the air-fuel ratio deviation is larger than a predetermined value, In the fuel injection amount correction control method for an internal combustion engine that performs correction relating to the fuel injection amount, the target air-fuel ratio is detected by the intake air amount detection means for the command injection amount that instructs the fuel injection amount and the air amount that is sucked into the combustion chamber The air-fuel ratio detecting means is calculated before the step of executing the correction relating to the fuel injection amount , which is calculated on the basis of the actual air amount obtained by the estimation or the estimated air amount obtained by estimating the amount of air sucked into the combustion chamber. Whether the sign of the deviation between the actual air quantity and the target air quantity is the same as the sign of the air-fuel ratio deviation. The To a step to calculate an exhaust gas temperature deviation based on the actual exhaust gas temperature Metropolitan detected a target exhaust air temperature is calculated based on the target air-fuel ratio in exhaust temperature detecting means, when the exhaust gas temperature deviation is smaller than a predetermined value If it is determined that there is an erroneous detection of the actual air-fuel ratio, and if it is determined that there is an erroneous detection of the air-fuel ratio detection means, the correction relating to the fuel injection amount is canceled and the erroneous detection of the intake air amount detection means is performed. If the sign of the deviation between the actual air amount and the target air quantity is the same as the sign of the air-fuel ratio deviation, the correction related to the fuel injection amount is canceled and the intake air amount detection is performed. If it is determined that there is an erroneous detection of the means, and it is determined that the sign of the deviation between the actual air amount and the target air amount is opposite to the sign of the air-fuel ratio deviation, the correction related to the fuel injection amount is corrected. It is characterized by performing .

  According to such a configuration, whether or not to perform correction control is determined according to erroneous detection when detecting the air-fuel ratio.

  A control device for correcting and controlling a fuel injection amount of an internal combustion engine, comprising: an air-fuel ratio detection means for detecting an air-fuel ratio of an exhaust passage; and a control means for controlling a correction amount related to the fuel injection amount, the above-mentioned internal combustion engine The fuel injection amount correction control method is executed.

  According to the fuel injection amount correction control method and control apparatus for an internal combustion engine according to the present invention, the detection error of the air-fuel ratio or the intake air amount is determined, and whether or not the correction related to the command injection amount is to be performed according to the determination result. Since it is determined, the correction can be appropriately controlled.

It is a figure which shows the outline of a structure containing the diesel engine which concerns on Embodiment 1 of this invention. 2 is a flowchart showing a rough flow of learning control of the ECU of FIG. 1. It is a flowchart explaining the content of step S1 of FIG. 2 in detail. It is a flowchart explaining the content of step S3 of FIG. 2 in detail. It is a flowchart explaining the content of step S5 of FIG. 2 in detail. 3 is a diagram illustrating a dependency relationship between data in the first embodiment. FIG. 6 is a flowchart showing a flow of learning control of the ECU according to the second embodiment. 10 is a part of a flowchart showing a flow of learning control of the ECU according to the third embodiment. 10 is a part of a flowchart showing a flow of learning control of the ECU according to the third embodiment. 14 is a flowchart showing a flow of learning control of the ECU according to the fourth embodiment.

Embodiments of the present invention will be described below with reference to the accompanying drawings.
Embodiment 1 FIG.
FIG. 1 shows a configuration including a diesel engine 100 which is an internal combustion engine according to the present invention. Since the configuration of the diesel engine itself is well known, only an outline is shown in FIG. The air drawn from the air inlet 10 is purified by the air cleaner 12 and then compressed by the turbocharger 14. Then, it is cooled by the intercooler 16 and flows into the combustion chamber 20 through the inlet manifold 18.
Further, fuel is injected into the combustion chamber 20 from the fuel injection device 22 and burned. After combustion, exhaust gas is discharged from the combustion chamber 20 to the exhaust manifold 24. The exhaust gas is used for compression of intake air in the turbocharger 14, then purified by the catalyst 26, and exhausted from the exhaust port 28.

An air flow meter 42 is provided on the upstream side of the air cleaner 12. The air flow meter 42 is intake air amount detection means, and detects the amount of air taken into the combustion chamber 20 of the diesel engine 100 via the air cleaner 12.
An exhaust temperature sensor 44 that is an exhaust temperature detection means is provided upstream of the catalyst 26. An A / F sensor 46 is provided downstream of the catalyst 26. The A / F sensor 46 is air-fuel ratio detection means, and detects information representing the air-fuel ratio (A / F) in the exhaust gas discharged from the diesel engine 100 via the catalyst 26.

Further, a rotational speed sensor 48 is provided as a rotational speed detection means for detecting the engine rotational speed in the diesel engine 100.
The specific configurations of the air flow meter 42, the exhaust temperature sensor 44, the A / F sensor 46, and the rotation speed sensor 48 are well known to those skilled in the art and will not be described.

  An ECU 40 that controls the operation of the diesel engine 100 is attached to the diesel engine 100. The ECU 40 can electrically communicate with the air flow meter 42, the exhaust temperature sensor 44, the A / F sensor 46, and the rotation speed sensor 48, and receives information transmitted from these sensors. The ECU 40 is electrically communicable with the fuel injection device 22 and controls the fuel injection amount in the diesel engine 100 by transmitting a command injection amount instructing the fuel injection amount to the fuel injection device 22.

  The ECU 40 has a configuration as a well-known electronic control device. The ECU 40 determines a command injection amount based on information received from the rotational speed sensor 48 and an accelerator opening sensor (not shown), and transmits the command injection amount to the fuel injection device 22 to control the fuel injection amount. The command injection amount may be corrected by a known parameter such as the engine temperature based on the oil temperature or the cooling water temperature, the intake air temperature, and the atmospheric pressure. The ECU 40 is also a learning control unit that performs learning related to the command injection amount and corrects the command injection amount according to the learning result. The ECU 40, the air flow meter 42, the exhaust temperature sensor 44, the A / F sensor 46, and the rotation speed sensor 48 constitute a device that controls learning related to the command injection amount.

  The ECU 40 includes a storage device (not shown). The storage device includes an air amount map for obtaining an intake air amount from the command injection amount and the engine speed, an air-fuel ratio map for obtaining an air fuel ratio from the intake air amount and the command injection amount, and an exhaust temperature from the command injection amount and the intake air amount. Is stored, and a second exhaust temperature map for determining the exhaust temperature from the commanded injection amount and the engine speed is stored. These maps are in a two-dimensional table format. For example, if the command injection amount value and the engine speed value are specified in the air amount map, the intake air amount value corresponding to these values is determined. Is done.

Next, the learning control executed by the ECU 40 according to the first embodiment will be described with reference to FIGS.
FIG. 2 is a flowchart showing a rough flow of learning control of the ECU 40.
First, the ECU 40 calculates a deviation between the actual air-fuel ratio detected by the A / F sensor 46 and the target air-fuel ratio determined based on information from other than the A / F sensor 46 (step S1).

FIG. 3 is a flowchart illustrating the details of step S1 in FIG. 2 in more detail. Step S1 in FIG. 2 includes steps S11 to S16 in FIG.
First, the ECU 40 acquires a command injection amount (step S11). The ECU 40 determines the command injection amount at any time by a known method, for example, and can obtain this by simply referring to the value.

  Next, the ECU 40 detects the actual air amount (step S12). This is performed, for example, by receiving a value representing the intake air amount detected by the air flow meter 42. This actual air amount is one piece of information representing the actual state of the diesel engine 100 determined based on the detection value of the sensor.

  Next, the ECU 40 determines a target air-fuel ratio (step S13). This is performed based on the command injection amount acquired in step S11 and the actual air amount detected in step S12. For example, the target air-fuel ratio is calculated as a value obtained by dividing the actual air amount by the command injection amount. Thus, the target air-fuel ratio is determined without referring to the information received from the A / F sensor 46. This target air-fuel ratio is one piece of information representing the target state of the diesel engine 100 determined based on the calculation.

Next, the ECU 40 detects the actual air-fuel ratio (step S14). This is performed, for example, by receiving a value representing the air-fuel ratio detected by the A / F sensor 46. This actual air-fuel ratio is one piece of information representing the actual state of the diesel engine 100 determined based on the detection value of the sensor.
Next, the ECU 40 calculates an air-fuel ratio deviation (step S15). This is performed by calculating the deviation between the actual air-fuel ratio acquired as described above and the target air-fuel ratio. The deviation is obtained as a difference, for example. This air-fuel ratio deviation is one of the state deviations representing the deviation between the target state and the actual state.

In this way, in step S1, the ECU 40 calculates the air-fuel ratio deviation. Here, when the air-fuel ratio deviation is zero, the actual air-fuel ratio detected by the A / F sensor 46 coincides with the target air-fuel ratio determined based on information from other than the A / F sensor 46. Will be. On the other hand, when the air-fuel ratio deviation is not zero, possible causes include, for example, the following three points.
-Case 1: When there is an error (injection amount deviation) between the command injection amount and the actual injection amount-Case 2: Between the actual air-fuel ratio detected by the A / F sensor 46 and the actual air-fuel ratio When there is a detection error (sensor deviation)-Case 3: When there is a detection error (sensor deviation) between the intake air amount detected by the air flow meter 42 and the actual intake air amount

Returning to FIG. 2, after step S1, the ECU 40 determines whether or not the absolute value of the air-fuel ratio deviation is larger than a predetermined threshold value (step S2).
When the air-fuel ratio deviation is equal to or less than the threshold value, the ECU 40 ends the process. That is, in this case, learning regarding the command injection amount is not executed. This corresponds to, for example, determining that the command injection amount is appropriate. Or it corresponds to determining that there is no injection amount deviation (at least below a predetermined value).

  When the air-fuel ratio deviation is larger than the threshold, the ECU 40 calculates the deviation between the actual exhaust temperature detected by the exhaust temperature sensor 44 and the target exhaust temperature determined based on information from other than the exhaust temperature sensor 44 ( Step S3).

FIG. 4 is a flowchart for explaining the details of step S3 of FIG. 2 in more detail. Step S3 in FIG. 2 includes steps S31 to S35 in FIG.
First, the ECU 40 acquires a command injection amount (step S31). This process is the same as step S11 in FIG. Further, this process may be omitted, and the value acquired in step S11 may be used.
Next, the ECU 40 detects the actual air amount (step S32). This process is the same as step S12 in FIG. Further, this process may be omitted, and the value acquired in step S12 may be used.

Next, the ECU 40 determines a target exhaust temperature (step S33). This is performed by referring to the first exhaust temperature map described above based on the command injection amount and the actual air amount. Thus, the target exhaust temperature is determined without referring to the information received from the exhaust temperature sensor 44.
Next, the ECU 40 detects the actual exhaust temperature (step S34). This is performed, for example, by receiving a value representing the temperature detected by the exhaust temperature sensor 44.

Next, the ECU 40 calculates the exhaust temperature deviation (step S35). This is performed by calculating the deviation between the actual exhaust temperature acquired as described above and the target exhaust temperature. The deviation is obtained as a difference, for example.
In this way, in step S3, the ECU 40 calculates the exhaust gas temperature deviation. Here, when the exhaust temperature deviation is zero, the actual exhaust temperature detected by the exhaust temperature sensor 44 matches the target exhaust temperature determined based on information from other than the exhaust temperature sensor 44. become.

Returning to FIG. 2, after step S3, the ECU 40 determines whether or not the absolute value of the exhaust gas temperature deviation is larger than a predetermined threshold (step S4).
This determination corresponds to determination of whether or not a detection error (sensor deviation) is included in the detection result of the A / F sensor 46. That is, assuming that the detection result of the exhaust temperature sensor 44 is correct, if the exhaust temperature deviation is less than or equal to the threshold value, the injection amount deviation is small, and the cause of the air-fuel ratio deviation is the sensor deviation of the A / F sensor 46. It is thought that. In this case, the ECU 40 ends the process. That is, in this case, since the injection amount deviation is considered to be small, learning regarding the command injection amount is not executed.

On the other hand, when the exhaust temperature deviation is larger than the threshold value (that is, when both the air-fuel ratio deviation and the exhaust temperature deviation are larger than the threshold value), it is considered that there is no information indicating the sensor deviation of the A / F sensor 46 in particular. In this case, it can be considered that the cause of the air-fuel ratio deviation is limited to one of the following.
-Case 1: When there is an error (injection amount deviation) between the command injection amount and the actual injection amount-Case 3: Detection between the intake air amount detected by the air flow meter 42 and the actual intake air amount When there is an error (sensor deviation)

  When the exhaust temperature deviation is larger than the threshold value in step S4, the ECU 40 calculates the deviation between the actual air amount detected by the air flow meter 42 and the target air amount determined based on information from other than the air flow meter 42. (Step S5).

FIG. 5 is a flowchart for explaining the details of step S5 of FIG. 2 in more detail. Step S5 in FIG. 2 includes steps S51 to S55 in FIG.
First, the ECU 40 acquires a command injection amount (step S51). This process is the same as step S11 in FIG. Further, this process may be omitted, and the value acquired in step S11 may be used.
Next, the ECU 40 acquires the engine speed of the diesel engine 100 (step S52). This is performed, for example, by receiving a value representing the engine speed detected by the speed sensor 48.
Next, the ECU 40 determines a target air amount (step S53). This is performed by referring to the air amount map described above based on the command injection amount and the engine speed acquired in steps S51 and S52. This target air amount is one piece of information representing the target state of the diesel engine 100 determined based on the calculation. Thus, the target air amount is determined without referring to the information received from the air flow meter 42.

Next, the ECU 40 detects the actual air amount (step S54). This is performed, for example, by receiving a value representing the intake air amount detected by the air flow meter 42. This actual air amount is one piece of information representing the actual state of the diesel engine 100 determined based on the detection value of the sensor.
Next, the ECU 40 calculates an air amount deviation (step S55). This is performed by calculating a deviation between the actual air amount acquired as described above and the target air amount. The deviation is obtained as a difference, for example. This air amount deviation is one of the state deviations representing the deviation between the target state and the actual state.

  In this way, in step S5, the ECU 40 calculates the air amount deviation. Here, when the air amount deviation is zero, the actual air amount detected by the air flow meter 42 matches the target air amount determined based on information from other than the air flow meter 42. .

  Returning to FIG. 2, after step S5, the ECU 40 determines whether or not the absolute value of the air amount deviation is larger than a predetermined threshold (step S6). If the air amount deviation is larger than the threshold value, it is determined whether or not the sign of the air amount deviation and the sign of the air-fuel ratio deviation are the same (step S7). For example, when the actual air amount is smaller than the target air amount (that is, rich as the air-fuel ratio) and the actual air-fuel ratio is smaller than the target air-fuel ratio (that is, rich as the air-fuel ratio), these deviations are the same. Have a sign. On the other hand, when the actual air amount is smaller than the target air amount (ie, the air-fuel ratio is rich) and the actual air-fuel ratio is larger than the target air-fuel ratio (ie, the air-fuel ratio is lean), these deviations are reversed. Have a sign.

When the sign of the deviation is the same in step S7, the ECU 40 ends the process. This corresponds to determining that the cause of the air-fuel ratio deviation is a sensor deviation of the air flow meter 42. Therefore, it is determined that the command injection amount is appropriate or there is no injection amount deviation (at least below a predetermined value). It corresponds to doing. In this case, learning regarding the command injection amount is not executed.
As a modification, step S7 may not be executed. That is, if the air amount deviation is larger than the threshold value in step S6, the ECU 40 may terminate the process as it is.

If the air amount deviation is equal to or smaller than the threshold value in step S6, the ECU 40 calculates an injection amount correction value (step S8). In this case, it is considered that there is no information indicating the sensor deviation of the air flow meter 42 in particular. Therefore, the cause of air-fuel ratio deviation and exhaust temperature deviation is
-Case 1: It can be considered that the restriction is made when there is an error (injection amount deviation) between the command injection amount and the actual injection amount.

Even when the sign of the deviation is reversed in step S7, the ECU 40 calculates the injection amount correction value (step S8). In this case, the cause of the air-fuel ratio deviation and exhaust temperature deviation is
-Case 1: When there is an error (injection amount deviation) between the command injection amount and the actual injection amount-Case 3: Detection between the intake air amount detected by the air flow meter 42 and the actual intake air amount It can be considered that both are cases where there is an error (sensor deviation).

  A specific method for determining the injection amount correction value in step S8 can be appropriately designed by those skilled in the art. For example, an expression expressing the injection amount correction value as a function of the air-fuel ratio deviation is stored in advance, and the injection amount correction value can be calculated by substituting the air-fuel ratio deviation into this function.

  Next, the ECU 40 writes the injection amount correction value in the learning map (step S9). As a result, the command injection amount is corrected, so that a value changed according to the correction value is used for the subsequent command injection amount. In this way, the ECU 40 controls learning related to the command injection amount based on the air-fuel ratio, the intake air amount, and the exhaust temperature.

  FIG. 6 is a diagram illustrating the dependency relationship between data determined by the above-described processing. For example, the air-fuel ratio deviation (A / F deviation) is a value calculated as the difference between the actual air-fuel ratio and the target air-fuel ratio in step S15, and this is the output of the ECU 40, the A / F sensor 46, and the air flow meter 42. However, it does not depend directly on the outputs of the rotation speed sensor 48 and the exhaust temperature sensor 44.

The flow of processing based on the above configuration will be described below using a specific example. In the following three examples, all assume the following conditions.
The actual air-fuel ratio is 20.0 and the target air-fuel ratio is 25.0. That is, the air-fuel ratio deviation is −5.0 (5.0 on the rich side).
-It is assumed that both the air-fuel ratio deviation and the exhaust temperature deviation are larger than the threshold value. That is, the process does not end at step S2 and step S4, and the processes after step S5 are executed.
-The threshold of the air amount deviation is 5% of the target air amount.

<Example 1: When branching from step S6 to step S8>
In Example 1, it is assumed that the actual air amount is 49 g / s and the target air amount is 50 g / s. In this case, the air amount deviation is -1 g / s (1 g / s on the rich side), which corresponds to 2% of the target air amount. Therefore, the air amount deviation (2%) is equal to or less than the threshold value (5%), and the intake air amount as the target is obtained. Therefore, it is determined that the cause of the air-fuel ratio deviation is the injection amount deviation, and the process branches from step S6 to step S8 to execute learning.

<Example 2: When ending in step S7>
In Example 2, it is assumed that the actual air amount is 45 g / s and the target air amount is 50 g / s. In this case, the air amount deviation is −5 g / s (5 g / s on the rich side), which corresponds to 10% of the target air amount. Therefore, the air amount deviation (10%) is larger than the threshold value (5%), and the process proceeds to step S7.

In step S7, since the air-fuel ratio deviation and the air amount deviation are both negative (rich side), these signs are the same. Therefore, it is determined that the cause of the air-fuel ratio deviation is a sensor deviation of the air flow meter 42, and since the injection quantity deviation is not the cause, learning of the injection quantity is not executed.
As a modification, if the absolute value of the air amount deviation is too large relative to the absolute value of the air-fuel ratio deviation, the injection amount deviation is likely to occur at the same time, so the injection amount is learned. May be. For example, when it is determined in step S7 that the signs of the deviations are the same, a step of comparing the air amount deviation and the air-fuel ratio deviation is provided, and if the difference or ratio is greater than a predetermined threshold, the process branches to step S8. It is good also as a structure.

<Example 3: When branching from step S7 to step S8>
In Example 3, it is assumed that the actual air amount is 55 g / s and the target air amount is 50 g / s. In this case, the air amount deviation is +5 g / s (5 g / s on the lean side), which corresponds to 10% of the target air amount. Therefore, the air amount deviation (10%) is larger than the threshold value (5%), and the process proceeds to step S7.

In step S7, since the air-fuel ratio deviation is negative (rich side) but the air amount deviation is positive (lean side), these signs are reversed. Therefore, it is determined that the cause of the air-fuel ratio deviation is both the injection amount deviation and the sensor deviation of the air flow meter 42, and the process branches to step S8 and learning is executed.
In this case, since the learning becomes excessive if it is included in the calculation of the injection amount correction value up to the amount corresponding to the sensor deviation of the air flow meter 42, the injection amount correction is considered in consideration of only the amount corresponding to the air-fuel ratio deviation. The value will be determined.

  As described above, according to the diesel engine 100 and the ECU 40 according to the first embodiment, it is determined whether or not the air flow meter 42 and the A / F sensor 46 are misaligned, and learning about the command injection amount is performed according to the result. Therefore, it is possible to appropriately control learning.

In Embodiment 1, diesel engine 100 may be another internal combustion engine, for example, a gasoline engine.
Further, the diesel engine 100 may be provided with an EGR device that recirculates the combustion gas in the exhaust pipe into the intake pipe. In this case, the target air amount is determined according to the EGR amount obtained from the command injection amount and the engine speed. The target A / F and the target exhaust temperature may be corrected, and the values and deviations of various sensors may be calculated.
The arrangement of the various sensors may be other than the arrangement shown in the first embodiment. For example, an A / F sensor or an exhaust temperature sensor installed in the exhaust pipe only needs to be installed in the exhaust pipe. The exhaust pipe upstream of the turbocharger 14, the exhaust pipe upstream of the catalyst 26, and the downstream of the catalyst 26. What is necessary is just to arrange | position to the side exhaust pipe. The arrangement shown in the first embodiment is an arrangement in which various sensors are often installed. In this case, it is not necessary to newly install various sensors.
The air amount map, the air-fuel ratio map, the first exhaust temperature map, and the second exhaust temperature map can be determined by using, for example, those selected as the characteristic center product from each sensor. In this way, it is possible to learn the injection amount within an appropriate range in consideration of variations among the sensors.
Further, these maps may take into account information other than the variables shown in the first embodiment. For example, you may correct | amend according to environmental conditions (outside temperature, water temperature, atmospheric pressure, etc.). Further, the correction may be performed based on the catalyst mode (whether it is the normal combustion mode or the PM regeneration combustion mode). Further, correction may be performed according to a deterioration coefficient corresponding to the travel distance.

Embodiment 2. FIG.
In the second embodiment, the order of the sensor deviation determination of the A / F sensor 46 and the sensor deviation determination of the air flow meter 42 are reversed in the first embodiment.
FIG. 7 is a flowchart showing a flow of learning control of the ECU according to the second embodiment. Steps S101 to S103 correspond to steps S1 to S3 of the first embodiment (FIG. 2), respectively.

Steps S104 and S105 correspond to steps S6 and S7 of the first embodiment. That is, first, sensor deviation determination of the air flow meter 42 is performed.
Step S106 corresponds to step S3 in the first embodiment.
Step S107 corresponds to step S4 in the first embodiment. That is, the sensor deviation determination of the A / F sensor 46 is performed after the sensor deviation determination of the air flow meter 42.
Steps S108 and S109 correspond to steps S8 and S9 of the first embodiment, respectively.

  In this way, even if the order of detection errors (sensor deviations) of the sensors is changed, the same processing can be executed to obtain the same effect.

Embodiment 3 FIG.
In the third embodiment, the sensor deviation and the injection amount deviation are determined by a method different from that in the first and second embodiments.
8a and 8b are flowcharts showing the flow of learning control of the ECU according to the third embodiment. The ECU according to the third embodiment first determines whether or not the air amount deviation is larger than a threshold value (steps S201 to S202). In steps S201 and S202, it is determined whether the air flow meter 42 has a sensor shift. If the air amount deviation is larger than the threshold value, it is determined that there is a sensor deviation of the air flow meter 42, and if not, it is determined that there is no sensor deviation of the air flow meter 42.

When it is determined that there is no sensor deviation of the air flow meter 42, the ECU determines whether the air-fuel ratio deviation is greater than a threshold value (steps S203 to S204). Here, as the target air-fuel ratio, a value obtained by dividing the actual air amount by the command injection amount is used.
If the air-fuel ratio deviation is less than or equal to the threshold value, it is determined that there is no sensor deviation of the A / F sensor 46 and that there is no injection amount deviation, and the ECU ends the process.

  When the air-fuel ratio deviation is larger than the threshold value, it is determined that either a sensor deviation of the A / F sensor 46 or an injection amount deviation exists. However, the presence / absence of each is not individually determined at this point. In this case, the ECU further determines whether or not the exhaust temperature deviation is larger than the threshold value (steps S205 to S206). Here, as the target exhaust temperature, a value obtained by referring to the first exhaust temperature map based on the actual air amount and the command injection amount is used.

When the exhaust gas temperature deviation is equal to or smaller than the threshold value, the ECU determines that the cause of the air-fuel ratio deviation is a sensor deviation of the A / F sensor 46, and therefore, determines that there is no injection amount deviation. In this case, the ECU ends the process.
When the exhaust gas temperature deviation is larger than the threshold value, the ECU determines that the cause of the air-fuel ratio deviation is an injection amount deviation. The learning process (steps S207 and S208) in this case is the same as steps S8 and S9 in the first embodiment (FIG. 2).

If it is determined in step S202 that there is a sensor deviation of the air flow meter 42, the ECU executes steps S213 to S218 in FIG. 8b. Steps S213 to S218 are processes corresponding to steps S203 to S208 of FIG. However, when there is a sensor deviation of the air flow meter 42, it is not appropriate to use the actual air amount from the air flow meter 42 as it is.
Therefore, in step S213, the target air-fuel ratio is determined by referring to the air-fuel ratio map based on the engine speed and the command injection amount, not based on the calculation using the actual air amount. In this case, it can be said that the target air-fuel ratio is calculated not using the actual air amount but using the estimated air amount estimated using the engine speed and the command injection amount.
Also in step S215, the target exhaust temperature is determined by referring to the second exhaust temperature map based on the engine speed and the command injection amount without using the actual air amount.
Other processes are the same as steps S203 to 208 in FIG. 8a.

In the above-described third embodiment, it is assumed that the sensor deviation of the rotational speed sensor 48, the deviation caused by the diesel throttle, the deviation caused by the supercharging pressure, and the deviation caused by EGR are negligible because there is no or almost no deviation. ing. Therefore, regardless of which one of the determination branches in step S202, it is possible to determine whether or not there is an injection amount deviation by calculating the exhaust gas temperature deviation next.
The exhaust temperature varies greatly depending on the engine temperature, the intake air temperature, the EGR amount, and the like, and is therefore less accurate than the air-fuel ratio. Therefore, by calculating the air-fuel ratio deviation with higher accuracy first, it is possible to improve the accuracy of the presence or absence of the injection amount deviation.

Embodiment 4 FIG.
In the first to third embodiments, learning control is performed using two sensors, the A / F sensor 46 and the air flow meter 42. In the fourth embodiment, learning control is performed using only the A / F sensor 46.
FIG. 9 is a flowchart showing a flow of learning control of the ECU according to the fourth embodiment. In the fourth embodiment, the processes in steps S5 to S7 are deleted from the first embodiment (FIG. 2). That is, steps S301 to S304 in the fourth embodiment correspond to steps S1 to S4 in the first embodiment, and steps S305 to S306 in the fourth embodiment correspond to steps S8 to S9 in the first embodiment.

  In the fourth embodiment, learning control is realized using only the A / F sensor 46. In this embodiment, since the sensor deviation of the air flow meter 42 is not determined, this corresponds to processing assuming that the air flow meter 42 is always accurate. That is, the sensor deviation determination of the A / F sensor 46 is performed based on the exhaust temperature deviation, but when it is determined that there is no sensor deviation of the A / F sensor 46, it is determined that the cause of the air-fuel ratio deviation is the injection amount deviation. To learn the injection amount.

  In the fourth embodiment, the calculation of the target air-fuel ratio in step S301 is based on the engine speed and the command injection amount obtained from the speed sensor 48, without using the actual air quantity obtained from the air flow meter 42. You may calculate with reference to an air fuel ratio map.

40 ECU (learning control means), 42 Air flow meter (intake air amount detection means),
44 exhaust temperature sensor, 46 A / F sensor (air-fuel ratio detection means), 48 rpm sensor, 100 diesel engine.

Claims (2)

An air-fuel ratio deviation is calculated based on the actual air-fuel ratio detected by the air-fuel ratio detection means and the target air-fuel ratio. If the air-fuel ratio deviation is larger than a predetermined value, the correction of the fuel injection amount is performed. In the fuel injection amount correction control method,
The target air-fuel ratio is
A command injection amount for instructing a fuel injection amount;
An actual air amount obtained by detecting the air amount sucked into the combustion chamber by the intake air amount detection means or an estimated air amount obtained by estimating the air amount sucked into the combustion chamber;
Calculated based on
Prior to performing the correction relating to the fuel injection amount, the step of determining erroneous detection of the air-fuel ratio detection means, the step of determining erroneous detection of the intake air amount detection means, the actual air amount and the target air Determining whether the sign of the deviation from the quantity and the sign of the air-fuel ratio deviation are the same ,
Calculating an exhaust temperature deviation based on the target exhaust temperature calculated based on the target air-fuel ratio and the actual exhaust temperature detected by the exhaust temperature detecting means;
When the exhaust temperature deviation is smaller than a predetermined value, it is determined that there is a false detection of the actual air-fuel ratio,
If it is determined that there is an erroneous detection of the air-fuel ratio detection means, the correction related to the fuel injection amount is canceled ,
When it is determined that there is a false detection of the intake air amount detection means, and it is determined that the sign of the deviation between the actual air quantity and the target air quantity is the same as the sign of the air-fuel ratio deviation , Cancel the correction related to the fuel injection amount,
When it is determined that there is a false detection of the intake air amount detection means, and it is determined that the sign of the deviation between the actual air quantity and the target air quantity is opposite to the sign of the air-fuel ratio deviation And a correction method for controlling the fuel injection amount of the internal combustion engine , wherein a correction relating to the fuel injection amount is performed . A control device for correcting and controlling a fuel injection amount of an internal combustion engine,
Air-fuel ratio detecting means for detecting the air-fuel ratio of the exhaust passage;
Control means for controlling a correction amount related to the fuel injection amount;
A control device for executing the fuel injection amount correction control method for an internal combustion engine according to claim 1 .

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