JP4613121B2 - Intake air amount detection device for internal combustion engine - Google Patents

Description

  The present invention relates to an intake air amount detection device for an internal combustion engine that detects an intake air amount using an intake air amount sensor provided in an intake system of the internal combustion engine.

  Conventionally, as this type of intake air amount detection device, for example, one disclosed in Patent Document 1 is known. In this intake air amount detection device, the intake air amount is estimated as the estimated intake air amount according to the operating state of the internal combustion engine. Further, the deviation between the intake air amount detected by the intake air amount sensor when the internal combustion engine is in a steady operation state and the estimated intake air amount estimated at that time is learned as a learning correction value. Further, such learning is performed for each of a large number of operating regions of the internal combustion engine divided by the rotational speed of the internal combustion engine and the opening degree of the accelerator pedal, and the learned correction value that is learned is made to correspond to the operating region. Is remembered. During the operation of the internal combustion engine, the learning correction value is read out according to the operation region at that time, and is used to compensate for the influence such as deterioration with time of the intake air amount sensor.

  As described above, in the conventional intake amount detection device, learning of the learning correction value is performed for each of a large number of operating regions on condition that the internal combustion engine is in a steady operating state. However, in general, the operation region of the internal combustion engine does not appear evenly during operation, and some of the steady operation is performed frequently, and others are performed rarely. For this reason, in the operation region where steady operation is difficult to be performed, the frequency of learning must be reduced, and learning cannot be sufficiently performed. As a result, in such an operation region, it becomes impossible to appropriately compensate for the influence of the intake air amount sensor due to deterioration over time. Further, since the learning correction value is stored in association with the operation area, a very large storage area is required for that purpose.

  The present invention has been made to solve the above-described problems, and can sufficiently secure an opportunity for learning a correction value for correcting the detected intake air amount, thereby appropriately detecting the intake air amount. An object of the present invention is to provide an intake air amount detection device for an internal combustion engine.

Japanese Patent No. 3089135

In order to achieve the above object, an intake air amount detection device 1 for an internal combustion engine 3 according to claim 1 is provided in an intake system of the internal combustion engine 3 (the intake pipe 4 in the embodiment (hereinafter the same in this section)), and the intake air An intake air amount sensor (air flow sensor 11) that detects the amount of intake air flowing through the system as a detected intake air amount QA, and operating state detection means that detects the operating state (engine speed NE, accelerator pedal opening AP) of the internal combustion engine 3 Crank angle sensor 14, accelerator opening sensor 16, ECU 2) and intake air amount estimating means (ECU 2) that estimates the amount of intake air flowing through the intake system as estimated intake air amount ESQA according to the detected operating state of internal combustion engine 3. and step 34), the detection intake air amount QA detected when the operating state of the internal combustion engine 3 is in a predetermined operating state, it has been achieved so far, for correcting the detected intake air amount QA By compensating with a positive value (intake air quantity learning correction value CLQA), to calculate the post-correction intake air amount CEDQA, when the calculated post-correction intake air amount CEDQA, the operating state of the internal combustion engine is in a predetermined operating condition based on the estimated estimated intake air amount ESQA, auxiliary correction value learning means for learning a positive value (ECU 2, step 23 to 27) and, in accordance with the detected intake air amount QA, the correction when correcting the detected intake air amount QA Using the reflection degree parameter determining means (ECU 2, step 41, FIG. 10) for determining the reflection degree parameter (reflection coefficient KRE) representing the reflection degree of the value, the detected intake air amount QA using the correction value and the determined reflection degree parameter And an intake air amount correcting means (ECU2, step 42) for correcting.

According to the intake air amount detection device for an internal combustion engine, the intake air amount flowing through the intake system is detected as the detected intake air amount by the intake air amount sensor, and the estimated intake air amount is estimated by the intake air amount estimating means according to the detected operating state. Estimated as a quantity. Then, the corrected intake air amount obtained when the operating state of the internal combustion engine is in a predetermined operating state is corrected by a correction value for correcting the detected intake air amount obtained so far, and then It calculates the intake air amount, the post-correction intake air amount calculated based on the estimated intake air quantity estimated when the operation state of the internal combustion engine is in a predetermined operating condition, compensation value, the correction value learning section Learned by.

  Thus, since the correction value is learned when the internal combustion engine is in a predetermined operating state, the learning value is set by setting the predetermined operating state to an operating state that reliably appears during the operation of the internal combustion engine. Enough opportunities can be secured. Further, since the number of correction values to be learned is equal to a predetermined operation state, for example, only one, it is possible to store correction values as compared with the conventional case where learning is performed for each of a number of operation regions. The storage area can be greatly reduced.

  Also, the reflection degree parameter determining means determines a reflection degree parameter representing the reflection degree of the correction value when correcting the detected intake air amount according to the detected intake air amount, and the intake air amount correcting means determines the correction value and the reflection degree parameter. The detected intake air amount is finally obtained by correcting the detected intake air amount using.

  The present invention is based on the following facts confirmed by experiments. That is, as shown in FIG. 11, in the case of a hot-wire type in which an intake air amount sensor is generally used, the output characteristic of the sensor after aging (shown by a solid line) is the output characteristic before deterioration (shown by a one-dot chain line). The deviation of the detected value relative to the actual intake air amount (hereinafter referred to as “detection error”) varies depending on the intake air amount and is almost unambiguous with respect to the intake air amount. It tends to be fixed. For this reason, for example, according to the output characteristics of the intake air amount sensor after such deterioration with time, the reflection degree parameter determining means determines the reflection degree parameter according to the detected intake air amount. Then, by using the reflection degree parameter determined in this way together when correcting the detected intake air amount with the correction value, the correction value has an appropriate degree according to the deviation of the output characteristic of the intake air amount sensor as described above. Thus, the intake air amount can be properly detected while appropriately compensating for the detection error.

  According to a second aspect of the present invention, in the intake air amount detection device 1 for the internal combustion engine 3 according to the first aspect, the reflection degree parameter determining means reflects the correction value in the detected intake air amount QA as the detected intake air amount QA increases. The reflection degree parameter is determined so that the degree becomes smaller (step 41, FIG. 10).

  According to this configuration, the reflection degree parameter is determined to be smaller as the detected intake air amount is larger. As described in the operation of the first aspect, the detection error of the intake air amount sensor is almost uniquely determined with respect to the intake air amount. Specifically, as shown in FIG. Tend to be. Therefore, by determining the reflection degree parameter as described above, the detection error can be more appropriately compensated according to the intake air amount.

  The invention according to claim 3 is the intake air amount detection device 1 of the internal combustion engine 3 according to claim 1 or 2, further comprising intake air temperature detection means (intake air temperature sensor 12) for detecting the intake air temperature TA, and the intake air amount. The estimation means estimates the estimated intake air amount ESQA further according to the detected intake air temperature TA (step 32, FIG. 6, step 34).

  According to this configuration, the intake air temperature is detected by the intake air temperature detection means, and the estimated intake air amount is estimated further in accordance with the detected intake air temperature. For example, since the density of the intake air decreases as the temperature of the intake air increases, the actual intake air amount changes according to the temperature of the intake air. Therefore, by estimating the estimated intake air amount further according to the temperature of the intake air, the estimated intake air amount can be accurately obtained while compensating for a substantial change in the intake air amount according to the temperature.

  According to a fourth aspect of the present invention, the intake air amount detecting device 1 for the internal combustion engine 3 according to any one of the first to third aspects further includes an intake pressure detecting means (intake pressure sensor 13) for detecting an intake pressure PBA. The intake air amount estimation means estimates the estimated intake air amount ESQA further according to the detected intake air pressure PBA (step 33, FIG. 7, step 34).

  According to this configuration, the intake pressure is detected by the intake pressure detection means, and the estimated intake amount is estimated further according to the detected intake pressure. For example, the higher the intake pressure, the higher the density of the intake air. Therefore, the actual intake air amount changes according to the intake air pressure. Therefore, by estimating the estimated intake amount further in accordance with the intake pressure, the estimated intake amount can be obtained with high accuracy while compensating for a substantial change in the intake amount in accordance with the pressure.

  According to a fifth aspect of the present invention, in the intake air amount detection device 1 for the internal combustion engine 3 according to any one of the first to fourth aspects, the internal combustion engine 3 supplies burnt gas generated by combustion in the combustion chamber to the combustion chamber. The EGR device 8 to be supplied is provided, and the predetermined operation state is a state in which the internal combustion engine 3 is in an idle operation state (step 1: YES) and the EGR device 8 is stopped (step 2: YES). It is characterized by that.

According to this configuration, the correction value is learned when the internal combustion engine is in an idle operation state and the EGR device is stopped. In the idle operation state, the intake air amount is relatively stable. Even in the idling state, when the burned gas is supplied to the combustion chamber by the operation of the EGR device, the intake air amount fluctuates accordingly. Therefore, as described above, the correction value learning is performed by setting the predetermined operation state as the correction value learning condition to a state in which the internal combustion engine is in the idle operation state and the EGR device is stopped. It is possible to appropriately carry out in a state where the intake air amount is stable without the influence of the supply of burnt gas on the intake air amount. Normally, when the internal combustion engine is started, the idling operation is performed and the EGR device is stopped. Therefore, the predetermined operation state appears reliably, so that sufficient learning opportunities can be secured.
According to a sixth aspect of the present invention, in the intake air amount detecting device 1 for the internal combustion engine 3 according to any one of the first to fifth aspects, the correction value learning means is a degree of deviation of the corrected intake air amount CEDQA from the estimated intake air amount ESQA. Based on the above, the learning coefficient KL is calculated (step 25, FIG. 8), and the correction value obtained this time is calculated by multiplying the calculated learning coefficient KL by the correction value obtained so far ( Step 27) When the corrected intake air amount CEDQA is deviated to the larger side with respect to the estimated intake air amount ESQA, the learning coefficient KL is calculated as a larger positive value that exceeds the value 1.0 as the degree of deviation is larger. When the corrected intake air amount CEDQA deviates to a smaller side, the larger the degree of deviation is, the smaller the value 1.0 is calculated, and the smaller the degree of deviation is, the smaller Of so that the inclination of the learning coefficient KL for degree becomes smaller, characterized in that it is calculated.
According to this configuration, the learning coefficient is calculated based on the degree of deviation of the corrected intake air amount from the estimated intake air amount, and the calculated learning coefficient is multiplied by the correction value obtained so far. Thus, the current correction value is calculated. In addition, when the corrected intake air amount is deviated to the larger side with respect to the estimated intake air amount, the learning coefficient is calculated to a larger positive value that exceeds the value 1.0 as the degree of deviation is larger. When the amount of intake air is deviated to a smaller side, the larger the degree of deviation is, the smaller the value 1.0 is calculated, and the smaller the degree of deviation, the smaller the slope of the learning coefficient with respect to the degree of deviation. It is calculated so as to be smaller.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. FIG. 1 schematically shows an intake air amount detection device 1 according to the present embodiment and an internal combustion engine (hereinafter referred to as “engine”) 3 to which the intake air amount detection device 1 is applied. The engine 3 is, for example, an in-line four-cylinder type diesel engine mounted on a vehicle (not shown).

  A combustion chamber (none of which is shown) is formed between the piston of each cylinder of the engine 3 and the cylinder head. An intake pipe 4 (intake system) and an exhaust pipe 5 are connected to the cylinder head, and a fuel injection valve (hereinafter referred to as “injector”) 6 is attached so as to face the combustion chamber.

  The injector 6 is disposed in the center of the top wall of the combustion chamber, and is connected in turn to a high-pressure pump and a fuel tank (both not shown) via a common rail. The fuel in the fuel tank is boosted to a high pressure by a high-pressure pump, then sent to the injector 6 through the common rail, and injected from the injector 6 into the combustion chamber. Further, the fuel injection amount of the injector 6 is set by an ECU 2 (to be described later) of the intake air amount detection device 1, and the valve opening time and the valve opening timing of the injector 6 are obtained by a drive signal from the ECU 2. To be controlled.

  The engine 3 is provided with a supercharger 7. The supercharger 7 includes a rotatable compressor blade 7a provided in the intake pipe 4, a rotatable turbine blade 7b provided in the exhaust pipe 5, and a plurality of rotatable variable vanes 7c (only two shown). ) And a shaft 7d for integrally connecting these blades 7a and 7b. The turbocharger 7 pressurizes the intake air in the intake pipe 4 by rotating the compressor blade 7a integrally therewith as the turbine blade 7b is rotationally driven by the exhaust gas in the exhaust pipe 5. Perform supercharging operation.

  The variable vane 7c is provided with an actuator (not shown) for driving them, and this actuator is controlled by a drive signal from the ECU 2, thereby controlling the opening degree of the variable vane 7c. , Control the supercharging pressure.

  An air flow sensor 11 (intake air amount sensor) is provided upstream of the supercharger 7 in the intake pipe 4. The air flow sensor 11 is of a hot-wire type, detects the amount of intake air flowing through the intake pipe 4 (hereinafter referred to as “intake amount”) as a detected intake amount QA, and outputs the detection signal to the ECU 2.

  The engine 3 is provided with an EGR device 8 having an EGR pipe 8a and an EGR control valve 8b. The EGR pipe 8a is connected to connect the downstream side of the intake pipe 5 with respect to the compressor blade 7a and the upstream side of the exhaust pipe 5 with respect to the turbine blade 7b. Through this EGR pipe 8a, a part of the exhaust gas of the engine 3 recirculates as EGR gas to the intake pipe 4 and flows into the combustion chamber. Thereby, NOx in the exhaust gas is reduced by lowering the combustion temperature in the combustion chamber.

  The EGR control valve 8b is composed of a butterfly valve provided in the EGR pipe 8a and a DC motor (none of which is shown) that drives the valve to open and close the EGR control valve 8b. By controlling the opening degree linearly, the amount of EGR gas flowing into the combustion chamber is controlled.

  An intake air temperature sensor 12 (intake air temperature detecting means) and an intake air pressure sensor 13 (intake air pressure detecting means) are provided at a collection portion of the intake manifold of the intake pipe 4. The intake air temperature sensor 12 detects intake air temperature (hereinafter referred to as “intake air temperature”) TA, and the intake pressure sensor 13 detects intake air pressure (hereinafter referred to as “intake air pressure”) PBA as an absolute pressure, and detects them. The signal is output to the ECU 2.

  Further, a magnet rotor is attached to the crankshaft of the engine 3, and a crank angle sensor 14 (operating state detecting means) is constituted by this magnet rotor and an MRE pickup (none of which are shown). The crank angle sensor 14 outputs a CRK signal and a TDC signal, which are pulse signals, to the ECU 2 as the crankshaft rotates.

  The CRK signal is output every predetermined crank angle (for example, 30 °). The ECU 2 obtains the rotational speed NE (hereinafter referred to as “engine rotational speed”) NE of the engine 3 based on the CRK signal. The TDC signal is a signal indicating that the piston is at a predetermined crank angle position near the TDC (top dead center) at the start of the intake stroke.

  A water temperature sensor 15 is attached to the main body of the engine 3. The water temperature sensor 15 detects the temperature (hereinafter referred to as “engine water temperature”) TW of cooling water circulating in a cylinder block (not shown) of the engine 3 and outputs a detection signal to the ECU 2.

  Further, the ECU 2 detects from the accelerator opening sensor 16 (driving state detecting means) and the vehicle speed sensor 17 respectively an operation amount (hereinafter referred to as “accelerator opening”) AP and vehicle speed VP of an accelerator pedal (not shown). A signal is output.

  The ECU 2 is constituted by a microcomputer including an I / O interface, a CPU, a RAM, a ROM, an EEPROM 2a, and the like. The ECU 2 learns and learns the intake air amount learning correction value CLQA for correcting the detected intake air amount QA according to the control program stored in the ROM in accordance with the detection signals from the various sensors 11 to 17 described above. The detected intake air amount QA is corrected based on the intake air amount learning correction value CLQA. In the present embodiment, the ECU 2 corresponds to an operating state detecting unit, an intake air amount estimating unit, a correction value learning unit, a reflection degree parameter determining unit, and an intake air amount correcting unit.

  Further, the ECU 2 controls the fuel injection amount and the like so that the engine speed NE becomes a predetermined target idle speed NEIDLE (for example, 850 rpm) when the engine 3 is in the idling operation state. Further, during idle operation of the engine 3, the EGR gas recirculation to the intake pipe 4 is stopped by controlling the EGR control valve 8b to a fully closed state within a predetermined time (for example, 8 seconds) from the start (see FIG. Hereinafter, such a stop of the EGR operation is referred to as “start-up EGR cut”).

FIG. 2 shows processing for determining whether or not the execution condition for learning the intake air amount learning correction value CLQA is satisfied. This process is executed every predetermined time (for example, 20 msec). First, in step 1 (illustrated as “S1”, the same applies hereinafter), it is determined whether or not the engine 3 is idling. In this determination, when all of the following conditions (a) to (c) are satisfied, it is determined that the engine is idling.
(A) Accelerator opening AP is substantially 0 (b) Engine speed NE is smaller than a predetermined threshold value NEREF (eg, 1200 rpm) (c) Vehicle speed VP is substantially 0

  If the answer to step 1 is NO and the engine is not idling, it is determined that the learning execution condition is not satisfied, and the execution condition satisfaction flag F_LEOK is set to “0” to indicate this (step 9). ), This process is terminated. On the other hand, when the answer to step 1 is YES, it is determined whether or not the above-described EGR cut at start-up is being performed (step 2). If the answer is NO and the EGR cut at start-up is not being performed, it is determined that the execution condition is not satisfied, and step 9 is executed.

  On the other hand, if the answer to step 2 is YES, it is determined whether or not the rotational speed deviation DNE is smaller than a predetermined threshold value DNEREF (step 3). This rotational speed deviation DNE is an absolute value of the deviation between the aforementioned target idle rotational speed NEIDLE and engine rotational speed NE.

  When the answer to step 3 is NO and DNE ≧ DNEREF, that is, when the engine speed NE is much larger or very small than the target idle speed NEIDLE, it is determined that the execution condition is not satisfied. Then, Step 9 is executed. This is because in such a case, since the engine speed NE is controlled to converge to the target idle speed NEIDLE, the intake air amount is likely to fluctuate, so that learning may not be performed appropriately.

  On the other hand, when the answer to step 3 is YES, that is, during idling, during start-up EGR cut, and when DNE <DNEREF, the engine speed average value NEAVE and the intake air temperature average value TAAVE are respectively calculated in steps 4 and 5. calculate. These engine speed average value NEAVE and intake air temperature average value TAAVE are moving average values of engine speed NE and intake air temperature TA from the current time to a predetermined n times (for example, 50) before, respectively.

  Next, in steps 6 and 7, a water temperature average value TWAVE and an intake pressure average value PAVE are calculated, respectively. The water temperature average value TWAVE and the intake pressure average value PAVE are respectively moving average values of the engine water temperature TW and the intake pressure PBA from the current time to the nth previous time. Next, the intake temperature average value TAAVE, the water temperature average value TWAVE, and the intake pressure average value PAVE calculated in steps 5 to 7 are respectively defined by the upper limit values TAH, TWH, PBAH and the lower limit values TAL, TWL, PBAL. It is determined whether it is within a predetermined range (step 8).

  If the answer to step 8 is NO and any of the intake air temperature average value TAAVE, the water temperature average value TWAVE, and the intake pressure average value PAVE is not within the predetermined range, it is determined that the execution condition is not satisfied. Step 9 is executed. This is because in such a case, the operating state of the engine 3 is not stable, and the intake air amount is likely to fluctuate, so that learning may not be performed appropriately.

  On the other hand, when the answer to step 8 is YES, that is, when all of the conditions of steps 1 to 3 and 8 are satisfied, it is determined that the execution condition is satisfied, The establishment flag F_LEOK is set to “1” (step 10), and this process is terminated.

  Next, the process of learning the learning correction value CLQA will be described with reference to FIG. This process is executed every predetermined time (for example, 20 msec). First, in step 21, it is determined whether or not an execution condition satisfaction flag F_LEOK is “1”. If the answer to this question is NO and the learning execution condition is not satisfied, the present process is terminated.

  On the other hand, when the answer to step 21 is YES and the execution condition is satisfied, an estimated intake air amount ESQA is calculated (step 22). The estimated intake air amount ESQA is an estimated intake air amount, and this calculation is performed in the ESQA calculation process shown in FIG. First, in step 31, the estimated intake air amount reference value BESQA is calculated by searching the BESQA table shown in FIG. 5 according to the rotation speed average value NEAVE calculated in step 4. In this BESQA table, the reference value BESQA is set to a larger value because the amount of intake air flowing through the intake pipe 4 per unit time increases as the rotation speed average value NEAVE increases.

  Next, the intake air temperature correction value CT is calculated by searching the CT map shown in FIG. 6 according to the water temperature average value TWAVE and the intake air temperature average value TAAVE (step 32). In this CT map, the intake air temperature correction value CT is set to a larger value as the water temperature average value TWAVE is larger and as the intake air temperature average value TAAVE is larger.

  Next, the intake pressure correction value CP is calculated by searching the CP table shown in FIG. 7 according to the intake pressure average value PAVE (step 33). In this CP table, the intake pressure correction value CP is set to a smaller value as the intake pressure average value PAVE is larger.

Next, using the reference value BESQA, the intake air temperature correction value CT, and the intake pressure correction value CP calculated in steps 31 to 33, an estimated intake air amount ESQA is calculated by the following equation (1) (step 34), and this processing is performed. Exit.
ESQA = BESQA / (CT · CP) (1)

  As described above, the estimated intake air amount ESQA is calculated by correcting (dividing) the reference value BESQA with the intake air temperature correction value CT and the intake pressure correction value CP. As described above, the intake air temperature correction value CT is calculated to be larger as the water temperature average value TWAVE is larger and the intake air temperature average value TAAVE is larger (step 32). The value is corrected to a smaller value by (1). This is because the larger the TWAVE value and the larger the TAAVE value, the lower the density of air in the intake pipe 4, thereby reducing the substantial intake amount. Further, as the intake pressure average value PAVE is larger, the intake pressure correction value CP is calculated to be a smaller value (step 33), so the estimated intake amount ESQA is corrected to a larger value. This is because the larger the intake pressure average value PAVE, the higher the density of the air in the intake pipe 4 and the greater the intake amount.

  Returning to FIG. 3, in step 23 following step 22, the corrected intake air amount CEDQA is calculated by subtracting the intake air amount learning correction value CLQA obtained so far from the detected intake air amount QA. If the intake air amount learning correction value CLQA has never been calculated, the value 0 is used as the intake air amount learning correction value CLQA obtained so far in this step 23.

  Next, an intake air amount ratio RQA is calculated by dividing the calculated corrected intake air amount CEDQA by the estimated intake air amount ESQA calculated in step 34 (step 24). The intake air amount ratio RQA represents the degree of deviation of the corrected intake air amount CEDQA from the estimated intake air amount ESQA when the estimated intake air amount ESQA is assumed to be appropriate.

  Next, the learning coefficient KL is calculated by searching the KL table shown in FIG. 8 based on the calculated intake air amount ratio RQA (step 25). In this KL table, the learning coefficient KL is set to a larger positive value as the intake air amount ratio RQA is larger, and is set to a value of 1.0 when the RQA is a value of 1.0. In addition, the slope of the learning coefficient KL is set to a smaller value when the RQA is close to the value 1.0, that is, when the deviation of the corrected intake air amount CEDQA from the estimated intake air amount ESQA is relatively small, and the RQA has a value of 1. When it is far from 0 and this deviation is relatively large, it is set to a larger value.

  Next, limit processing is performed on the calculated learning coefficient KL (step 26). Specifically, the learning coefficient KL is compared with a predetermined upper limit value KLH and a lower limit value KLL, and is set to the upper limit value KLH when KL> KLH, and is set to the lower limit value KLL when KL <KLL.

  Next, the present intake air amount learning correction value CLQA is calculated by multiplying the learning coefficient KL obtained as described above by the intake air amount learning correction value CLQA obtained so far (step 27).

  As described above, when the intake air amount ratio RQA is 1.0, that is, the corrected intake air amount CEDQA obtained by subtracting and correcting the detected intake air amount QA by the intake air amount learning correction value CLQA is deviated from the estimated intake air amount ESQA. If not, the learning coefficient KL is set to a value of 1.0 in step 25, so that the current intake air amount learning correction value CLQA is held at its previous value in step 27. The learning coefficient KL increases as the intake air amount ratio RQA is larger than 1.0, that is, the corrected intake air amount CEDQA shifts to the larger side with respect to the estimated intake air amount ESQA. Since it is set to a larger value that exceeds the value 1.0, the intake air amount learning correction value CLQA is learned and corrected to a larger value. Conversely, the learning coefficient KL has a value of 1 as the intake air amount ratio RQA is smaller than the value 1.0 and the corrected intake air amount CEDQA is shifted to a smaller side with respect to the estimated intake air amount ESQA. Since it is set to a smaller value below 0.0, the intake air amount learning correction value CLQA is learned and corrected to a smaller value. As described above, the intake air amount learning correction value CLQA can be appropriately learned so that the corrected intake air amount CEDQA becomes equal to the estimated intake air amount ESQA.

  The slope of the learning coefficient KL is set to a smaller value when the intake air amount ratio RQA is close to the value 1.0, and is set to a larger value when the intake air amount ratio RQA is far from the value 1.0. . Thereby, when the deviation of the corrected intake air amount CEDQA from the estimated intake air amount ESQA is small, it is possible to prevent the intake air amount learning correction value CLQA from being excessively learned and corrected.

  Furthermore, basically, since the intake air amount learning correction value CLQA is calculated based on the detected intake air amount QA and the estimated intake air amount ESQA at that time, the deviation of the detected intake air amount QA from the estimated intake air amount ESQA can be quickly eliminated. Can do. Further, as the detected intake air amount to be compared with the estimated intake air amount ESQA, the detected intake air amount QA is not used as it is, but the detected intake air amount QA is more appropriately corrected by the intake air amount learning correction value CLQA obtained so far. The intake air amount learning correction value CLQA is learned using the corrected intake air amount CEDQA. As a result, the intake amount learning correction value CLQA is appropriately set while suppressing the influence caused by the failure to obtain the proper estimated intake air amount ESQA and the influence caused by fluctuations in the output of the air flow sensor 11 caused by the intake air pulsation of each cylinder. Can be requested. Such an effect is directly reflected in the intake air amount learning correction value CLQA when the detected intake air amount QA is used as it is as the detected intake air amount to be compared with the estimated intake air amount ESQA. Therefore, it cannot be obtained.

  Further, for example, when learning the intake air amount learning correction value CLQA by a weighted average of the deviation between the current estimated intake air amount ESQA and the detected intake air amount QA and the previous value of the intake air amount learning correction value CLQA, the learning is appropriately performed. Therefore, it is necessary to appropriately set a weighting factor for the weighted average. On the other hand, in the present embodiment, as apparent from the learning method described above, since such a weighting factor is not used, it is possible to eliminate problems caused by improperly setting the weighting factor.

  In step 28 following step 27, limit processing is performed on the calculated intake air amount learning correction value CLQA, and this processing is terminated. Specifically, the intake amount learning correction value CLQA is compared with a predetermined upper limit value CLQAH and a lower limit value CLQAL, and is set to the upper limit value CLQAH when CLQA> CLQAH, and is set to the lower limit value CLQAL when CLQA <CLQAL. The intake air amount learning correction value CLQA obtained as described above is stored in the EEPROM 2a.

  Next, a process for correcting the detected intake air amount QA will be described with reference to FIG. This process is executed every predetermined time (for example, 20 msec). First, in step 41, the reflection coefficient KRE is calculated by searching the KRE table shown in FIG. 10 according to the detected intake air amount QA.

  This KRE table defines the relationship between the detected intake air amount QA and the reflection coefficient KRE according to the output characteristics of the intake air amount sensor shown in FIG. In this KRE table, the reflection coefficient KRE is set to a positive value. When QA ≦ the first predetermined value QA1, it is set to a predetermined maximum value KREMAX (for example, 1.0), and the first predetermined value QA1 and the first predetermined value QA1. Between Q2 and the second predetermined value QA2, which is larger than the second predetermined value QA2, the smaller the value, the smaller is set linearly. When QA ≧ QA2, the minimum value KREMIN (for example, 0) is set. The first predetermined value QA1 corresponds to the intake air amount obtained during idling and during start-up EGR cut. Further, the second predetermined value QA2 is set to an intake amount having a detection error of 0, that is, a predetermined value α in the output characteristics after aging shown in FIG.

Next, using the calculated reflection coefficient KRE and the intake air amount learning correction value CLQA obtained in step 28, a final intake air amount QAC is calculated by the following equation (2) (step 42), and this process is terminated.
QAC = QA-CLQA · KRE (2)
The final intake air amount QAC is used as a parameter for controlling the fuel injection amount and the EGR gas amount during operation of the engine 3.

  As described above, according to the present embodiment, the intake air amount learning correction value CLQA is learned during idling (step 1: YES) and during start-up EGR cut (step 2: YES). This learning can be appropriately performed in a state where the intake air amount is stable, and can be reliably executed when the engine 3 is started, and a sufficient learning opportunity can be secured. Further, since only one intake amount learning correction value CLQA needs to be learned, the storage area can be greatly reduced as compared with the conventional case where learning is performed for each of a large number of operation areas.

  Further, when the detected intake air amount QA is corrected to obtain the final intake air amount QAC, the reflection coefficient KRE is used together with the intake air amount learning correction value CLQA (step 42), and this reflection coefficient KRE has a large detected intake air amount QA. The smaller the value is set (step 41, FIG. 10). Thereby, the deviation of the detected intake air amount QA with respect to the actual intake air amount can be compensated more appropriately according to the intake air amount, and therefore, an appropriate final intake air amount QAC can be obtained.

  Further, the estimated intake air amount is corrected by correcting the reference value BESQA calculated according to the engine speed NE according to the intake air temperature TA and the intake air pressure PBA (step 32, FIG. 6, step 33, FIG. 7, step 34). ESQA is calculated. Therefore, the estimated intake air amount ESQA can be obtained with high accuracy while compensating for a substantial change in the intake air amount according to the temperature and pressure.

  In addition, this invention can be implemented in various aspects, without being limited to the described embodiment. For example, learning of the intake air amount learning correction value CLQA is not limited to the method described in the embodiment, and may be performed by another appropriate method. For example, in the embodiment, the intake air amount ratio RQA is calculated by the ratio of the corrected intake air amount CEDQA, which is the difference between the detected intake air amount QA and the intake air amount learning correction value CLQA, and the estimated intake air amount ESQA. Instead of the corrected intake air amount CEDQA, the detected intake air amount QA may be used as it is. Alternatively, learning of the intake air amount learning correction value CLQA may be performed by calculating a deviation between the detected intake air amount QA and the estimated intake air amount ESQA, and performing a weighted average of the deviation and the previous value of the intake air amount learning correction value CLQA. .

  Further, in the embodiment, the learning of the intake air amount learning correction value CLQA is performed during idle operation and during start-up EGR cut, but instead of this or together with this, it is ensured during operation of the engine 3. The learning may be performed when the vehicle is in another predetermined one or a plurality of operating states that appear in the above and the intake air amount is relatively stable. When learning is performed in a plurality of operating states as described above, when correcting the detected intake air amount QA, the intake air amount learning correction value CLQA learned for each of the plurality of operating states is closest to the operating state at that time. By using what is learned in the operating state, the deviation of the detected intake air amount QA from the actual intake air amount can be compensated more finely and appropriately.

  Further, in the embodiment, when the detected intake air amount QA ≧ the second predetermined value QA2, the reflection coefficient KRE is uniformly set to the minimum value KREMIN (for example, value 0), but is set as follows. Also good. For example, as shown in FIG. 11, when the intake air amount is greater than the predetermined value α, the output error after the deterioration of the intake air sensor over time is a negative detection error, that is, the detected value is smaller than the actual intake air amount. Since the deviation tends to increase as the intake air amount increases, the reflection coefficient KRE may be set in accordance with such a tendency.

  In the embodiment, the EGR device is of a type in which a part of the exhaust gas is recirculated into the intake pipe 4 via the EGR pipe 8a, but instead of or in addition to this, the exhaust valve of the engine 3 is used. A so-called internal EGR type in which part of the burned gas remains in the combustion chamber by advancing the valve closing timing (not shown) or the like may be used. Furthermore, although embodiment is an example which applied this invention to the diesel engine for vehicles, this invention is not restricted to this, Other types of engines, for example, a gasoline engine, an engine of another use, For example, the present invention can be applied to a marine vessel propulsion engine such as an outboard motor having a crankshaft arranged in a vertical direction. In addition, it is possible to appropriately change the detailed configuration within the scope of the gist of the present invention.

1 is a diagram schematically showing an intake air amount detection device according to an embodiment and an internal combustion engine to which the intake air amount detection device is applied. FIG. It is a flowchart which shows an execution condition determination process. It is a flowchart which shows a CLQA learning process. It is a flowchart which shows the subroutine of the ESQA calculation process of step 22 of FIG. It is an example of the BESQA table used by the process of FIG. It is an example of CT map used by the process of FIG. It is an example of CP table used by the process of FIG. 4 is an example of a KL table used in the process of FIG. It is a flowchart which shows a QA correction process. 10 is an example of a KRE table used in the process of FIG. It is a figure which shows the output characteristic of a hot wire type intake air amount sensor before deterioration with time and after deterioration.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Intake amount detection apparatus 2 ECU (Operating state detection means, intake amount estimation means, correction value learning means,
Reflection degree parameter determination means, intake air amount correction means)
3 Engine 4 Intake pipe (intake system)
8 EGR device 11 Air flow sensor (intake air amount sensor)
12 Intake air temperature sensor (Intake air temperature detection means)
13 Intake pressure sensor (Intake pressure detection means)
14 Crank angle sensor (operating state detection means)
16 Accelerator opening sensor (operating state detection means)
QA Detected intake air amount NE Engine speed (Operating state of internal combustion engine)
AP accelerator opening (operating state of internal combustion engine)
ESQA Estimated intake air amount CLQA Intake air amount learning correction value (correction value)
CEDQA corrected post-intake air amount KRE reflection coefficient (reflection degree parameter)
KL learning coefficient TA Intake temperature PBA Intake pressure

Claims (6)

An intake air amount sensor that is provided in the intake system of the internal combustion engine and detects the amount of intake air flowing through the intake system as a detected intake air amount;
An operating state detecting means for detecting an operating state of the internal combustion engine;
Intake amount estimation means for estimating the amount of intake air flowing through the intake system as an estimated intake amount according to the detected operating state of the internal combustion engine;
Correction is performed by correcting the detected intake air amount detected when the operating state of the internal combustion engine is in a predetermined operating state with a correction value for correcting the detected intake air amount obtained so far. calculates a rear intake air amount, on the basis of said estimated intake air quantity estimated when the post-correction intake air amount that is the calculated, the operating state of the internal combustion engine is in the predetermined operating condition, before Kiho positive Correction value learning means for learning a value;
Reflection degree parameter determining means for determining a reflection degree parameter representing the degree of reflection of the correction value when correcting the detected intake air amount according to the detected intake air amount;
An intake air amount correcting means for correcting the detected intake air amount using the correction value and the determined reflection degree parameter;
An intake air amount detection device for an internal combustion engine, comprising:   The reflection degree parameter determination means determines the reflection degree parameter so that the reflection degree of the correction value to the detected intake air amount becomes smaller as the detected intake air amount becomes larger. The intake air amount detection device for an internal combustion engine according to claim 1. Intake temperature detecting means for detecting the temperature of the intake air is further provided,
The intake air amount detection device for an internal combustion engine according to claim 1 or 2, wherein the intake air amount estimation means estimates the estimated intake air amount further in accordance with the detected intake air temperature. Intake pressure detecting means for detecting the pressure of the intake air is further provided,
4. The intake air amount detection device for an internal combustion engine according to claim 1, wherein the intake air amount estimation means estimates the estimated intake air amount further according to the detected intake air pressure. . The internal combustion engine includes an EGR device that supplies burned gas generated by combustion in a combustion chamber to the combustion chamber;
The intake air of the internal combustion engine according to any one of claims 1 to 4, wherein the predetermined operation state is a state in which the internal combustion engine is in an idle operation state and the EGR device is stopped. Quantity detection device. The correction value learning means includes
Based on the degree of deviation of the corrected intake air amount from the estimated intake air amount, a learning coefficient is calculated, and the calculated learning coefficient is multiplied by the correction value obtained so far. Calculating the correction value of
When the corrected intake air amount is deviated to the larger side with respect to the estimated intake air amount, the learning coefficient is calculated to a larger positive value that exceeds the value 1.0 as the degree of deviation is larger. When the corrected intake air amount deviates to the smaller side, the larger the degree of deviation is, the smaller the value 1.0 is calculated, and the smaller the degree of deviation is, the smaller the degree of deviation is. The intake air amount detection device for an internal combustion engine according to any one of claims 1 to 5, wherein the learning coefficient is calculated so that the gradient of the learning coefficient becomes smaller.

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