JP2016020642A - Internal combustion engine control unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To correct an intake air flow volume to correspond to a variation in an output from intake-air-flow-volume detection means, and estimate an atmospheric pressure in a wide operation range with high accuracy while exerting a throttle degree-of-opening learning control corresponding to a difference among throttles.SOLUTION: An intake-air-quantity correction coefficient is calculated on the basis of a fuel correction coefficient for absorbing a variation in an air flow sensor 2, and an intake air quantity is corrected. An effective opening area is calculated using the corrected air intake quantity, a throttle degree-of-opening learned value is computed from the calculated effective opening area and a degree of opening of a throttle, an atmospheric pressure estimated value is updated with the statistical dispersion of a deviation between the degree of opening of the throttle in light of the throttle degree-of-opening learned value and an actual degree of opening of the throttle 4 set as a criterion while learning a relation between the degree of opening of the throttle 4 and the effective opening area for the difference among throttles.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a control device for an internal combustion engine provided with an atmospheric pressure estimating means for estimating an atmospheric pressure applied to calculation of a control parameter of the internal combustion engine.

  2. Description of the Related Art In recent years, an engine control method called so-called torque base control that uses engine output shaft torque as a required value of driving force from a driver or vehicle side and controls engine generated torque using this as an index has become widespread. In this torque-based control, the target torque of the engine is determined based on the operation amount of the accelerator pedal by the driver, and the throttle opening is set so that the target intake air flow rate that can generate the target torque is sucked into the engine. (Hereinafter referred to as throttle opening). The engine output is controlled to the target torque by controlling the fuel injection amount and ignition timing according to the actual intake air flow rate (hereinafter referred to as the actual intake air flow rate), realizing the driving performance required by the driver. Is done.

  In order to realize such a target intake air flow rate corresponding to the target torque of the engine, in an engine control device that controls the throttle opening by driving an actuator connected to the throttle, the target intake air flow rate Applying to the flow rate calculation formula of the throttle type flow meter based on the pressure ratio and throttle opening area etc., the target opening area of the throttle is obtained, and the throttle opening so as to achieve the target opening area of this throttle Means have been proposed for controlling an actuator provided in series.

  However, in order to calculate the throttle opening degree that achieves the target intake air flow rate by applying it to the flow rate calculation formula of the throttle type flow meter, the atmospheric pressure, the intake pipe pressure (intake manifold pressure, hereinafter referred to as the intake manifold pressure). In addition, a physical quantity before and after the throttle, such as the intake air temperature, is required, and a sensor for detecting these needs to be attached. However, if all the sensors are attached, the cost increases. Therefore, a method for estimating the physical quantity without using the sensors has been proposed.

  For example, as a method of estimating atmospheric pressure without using an atmospheric pressure sensor, Japanese Patent No. 5462390 (Patent Document 1) obtains an intake air flow rate from an effective opening area obtained from a throttle opening and an estimated atmospheric pressure value. There has been proposed a method for adjusting the estimated atmospheric pressure so that the intake air flow rate matches the target intake air flow rate. However, in this method, when there is an error in the relationship between the throttle opening and the effective opening area due to variations in the throttle difference, the error is reflected in the estimated atmospheric pressure, and the actual atmospheric pressure (hereinafter referred to as actual There was a problem that it would be an error.

  As a method for solving the problem with respect to the machine difference variation of the throttle, the applicant of the present application, in the application of Japanese Patent Application No. 2014-23903, uses the learning of the relationship between the throttle opening and the effective opening area to estimate the atmospheric pressure. A control apparatus for an internal combustion engine having an estimation means is proposed. That is, the atmospheric pressure estimation means proposed in the application of Japanese Patent Application No. 2014-23903 includes effective opening area calculation means for calculating an effective opening area corresponding to the throttle opening, and learning about the relationship between the effective opening area and the throttle opening. A throttle opening learning value calculating means for calculating a value, an error variation calculating means for calculating an error variation from an error between the corrected learning value, and a variation range determination for determining whether the error variation is within a predetermined range Means, an atmospheric pressure estimated value updating means for updating the atmospheric pressure estimated value, and a target throttle opening calculating means for calculating the target throttle opening using the updated atmospheric pressure estimated value. The throttle opening is controlled to the throttle opening.

Japanese Patent No. 5462390

  However, in the method proposed in the application of Japanese Patent Application No. 2014-23903, when there is variation in the output of the intake air flow rate detection means, the calculated effective opening area and the actual opening of the throttle (hereinafter referred to as actual throttle opening). There is a problem that the atmospheric pressure cannot be estimated correctly.

  The present invention has been made to solve the above-described problems, and performs intake air flow rate correction corresponding to variations in the output of the intake air flow rate detection means, and performs throttle opening learning control corresponding to variations in machine differences of the throttle. However, an object of the present invention is to provide a control device for an internal combustion engine that can accurately estimate the atmospheric pressure in a wide operating region.

An internal combustion engine control apparatus according to the present invention is an internal combustion engine control apparatus provided with an atmospheric pressure estimation means for estimating an atmospheric pressure applied to calculation of a control parameter of the internal combustion engine, and detects an operating state of the internal combustion engine. Operating state detection means for performing calculation, target intake air flow rate calculating means for calculating a target air flow rate based on the operating state of the internal combustion engine, and target air-fuel ratio calculating means for calculating a target air-fuel ratio based on the operating state of the internal combustion engine And a throttle provided in the intake passage of the internal combustion engine,
By controlling the throttle opening, the effective opening area of the intake passage is changed, and the throttle opening control means for variably controlling the intake air amount to the internal combustion engine, and the actual opening of the throttle are detected. Throttle opening detection means, intake air flow rate detection means for detecting the actual intake air flow rate to the internal combustion engine, pressure detection means for detecting the pressure on the internal combustion engine side of the throttle as an intake manifold pressure, Intake air temperature detecting means for detecting the intake air temperature on the atmosphere side, air fuel ratio calculating means for detecting the air fuel ratio after combustion, and fuel injection amount setting for setting the fuel injection amount based on the target air flow rate and the target air fuel ratio And the fuel injection amount setting means based on the air-fuel ratio detected by the air-fuel ratio calculating means and the target air-fuel ratio calculated by the target air-fuel ratio calculating means. Fuel correction coefficient calculating means for calculating a fuel correction coefficient for correcting the fuel injection amount; fuel injection means for injecting fuel corrected based on the fuel correction coefficient calculated by the fuel correction coefficient calculating means; and the fuel correction. An intake air flow rate correction coefficient calculating means for calculating an intake air flow rate correction coefficient based on a coefficient, and an intake air flow rate for correcting the actual intake air flow rate using the intake air flow rate correction coefficient calculated by the intake air flow rate correction coefficient calculating means. Based on the correction means, the estimated atmospheric pressure, the intake air flow rate corrected by the intake flow rate correction means, the intake manifold pressure, and the intake air temperature, the actual effective opening area corresponding to the actual opening of the throttle The effective opening area calculating means for calculating the effective opening area, the actual effective opening area calculated by the effective opening area calculating means, the actual opening of the throttle, And a is the effective opening area and the relationship map of the throttle opening, comprising: a throttle opening learning value calculation means for calculating a throttle opening degree learning value, and the atmospheric pressure estimating means,
The actual effective opening area, the actual opening of the throttle, the variation calculating means for calculating the error variation based on the relationship map of the effective opening area corrected by the throttle opening learning value and the throttle opening, and the actual Learning upper and lower limit determination means for determining whether the relationship between the effective opening area of the throttle and the actual opening of the throttle is within a predetermined range based on the relationship map between the effective opening area and the throttle opening, and the variation A variation range determination unit that determines whether or not the error variation calculated by the calculation unit is within a predetermined range; and a relationship between the actual effective opening area and the actual opening of the throttle is outside the predetermined range; and An atmospheric pressure estimated value updating means for updating an atmospheric pressure estimated value when the error variation is outside a predetermined range, and the atmospheric pressure estimated value updating means updates the atmospheric pressure estimated value. It calculates a target throttle opening degree by using a by atmospheric pressure estimates and controls the throttle opening.

  According to the control apparatus for an internal combustion engine according to the present invention, the intake air flow correction coefficient is calculated based on the fuel correction coefficient in order to absorb the variation of the intake air flow detection means, and the effective opening area is determined using the corrected intake air flow. By calculating, the relationship between the effective opening area and the actual opening of the throttle is brought close to the normal state, and at the same time, the throttle opening learning control is performed to absorb the machine difference variation of the throttle. And by updating the atmospheric pressure estimated value based on the statistical variation in the relationship between the throttle opening and the effective opening area, the atmospheric pressure can be accurately adjusted in a wide operating range while correcting the intake air flow rate for estimating the atmospheric pressure. There is an effect that can be estimated.

1 is a schematic configuration diagram of an engine to which an internal combustion engine control apparatus according to Embodiment 1 of the present invention is applied. FIG. It is a block diagram which shows schematic structure of the engine control part which concerns on Embodiment 1 of this invention. It is a flowchart which shows the atmospheric pressure estimation process of the control apparatus of the internal combustion engine which concerns on Embodiment 1 of this invention. It is a flowchart which shows the intake air flow rate correction | amendment process of the control apparatus of the internal combustion engine which concerns on Embodiment 1 of this invention. It is a flowchart which shows the throttle opening error dispersion | variation calculation process of the control apparatus of the internal combustion engine which concerns on Embodiment 1 of this invention. It is explanatory drawing which shows the relationship between the effective opening area of the control apparatus of the internal combustion engine which concerns on Embodiment 1 of this invention, and throttle opening. It is explanatory drawing which shows the learning range in the relationship between the effective opening area of the control apparatus of the internal combustion engine which concerns on Embodiment 1 of this invention, and throttle opening. FIG. 3 is a control block diagram schematically showing a throttle opening learning value calculation processing means of the control apparatus for an internal combustion engine according to the first embodiment of the present invention. It is a control block diagram which shows roughly the storage processing means of the long time learning value of the control apparatus of the internal combustion engine which concerns on Embodiment 1 of this invention. It is explanatory drawing which shows roughly the calculation method of the throttle opening learning basic value of the control apparatus of the internal combustion engine which concerns on Embodiment 1 of this invention. It is explanatory drawing which shows roughly the relationship which the throttle opening can take with respect to the effective opening area of the control apparatus of the internal combustion engine which concerns on Embodiment 1 of this invention. It is explanatory drawing which shows roughly the storage process of the long time learning value of the control apparatus of the internal combustion engine which concerns on Embodiment 1 of this invention. It is explanatory drawing which shows roughly the monotonous increase process of the control apparatus of the internal combustion engine which concerns on Embodiment 1 of this invention. It is a flowchart which shows the atmospheric pressure estimation process of the control apparatus of the internal combustion engine which concerns on Embodiment 2 of this invention. It is a flowchart which shows the effective opening area error dispersion | variation calculation process of the control apparatus of the internal combustion engine which concerns on Embodiment 2 of this invention. It is explanatory drawing which shows the relationship between the throttle opening of an internal combustion engine control apparatus which concerns on Embodiment 2 of this invention, and an effective opening area. It is explanatory drawing which shows the learning range in the relationship between the throttle opening degree and effective opening area of the control apparatus of the internal combustion engine which concerns on Embodiment 2 of this invention.

  A preferred embodiment of an internal combustion engine control apparatus according to the present invention will be described below with reference to the drawings.

Embodiment 1 FIG.
FIG. 1 is a schematic configuration diagram of an engine to which an internal combustion engine control apparatus according to Embodiment 1 of the present invention is applied. FIG. 2 is a block diagram illustrating a schematic configuration of an engine control unit according to Embodiment 1. It is.

  First, a schematic configuration of an engine to which the control device for an internal combustion engine according to the first embodiment is applied will be described with reference to FIG. An air flow sensor (hereinafter referred to as AFS) 2 as an intake air flow rate detecting means for detecting the intake air flow rate is provided upstream of the intake system of the engine 1, and an intake air temperature sensor 3 is further provided. The sensor is provided in the AFS 2 or as a separate sensor. A throttle for adjusting the intake air flow rate, for example, an electronically controlled throttle 4 that can be electrically controlled, is provided on the engine 1 side downstream of the AFS 2.

  In order to detect the opening degree of the electronic control throttle 4, a throttle opening degree sensor 5 is provided. Further, a pressure sensor 8 that detects an intake manifold pressure (hereinafter referred to as intake manifold pressure) that is a pressure in a space (hereinafter referred to as intake manifold) including the inside of the surge tank 6 and the intake manifold 7 downstream of the electronic control throttle 4. Is provided. Here, instead of the AFS 2, a method of estimating the intake air flow rate based on the intake manifold pressure (a so-called S / D (speed density) method) may be used, and the intake air temperature sensor 3 is provided in the intake manifold. Also good.

  An injector 9 for injecting fuel is provided in the vicinity of the intake valve including the intake manifold 7 and the cylinder. The intake valve and the exhaust valve have an intake VVT (Variable Valve Timing) for making the valve timing variable. 10 and exhaust VVT 11 are provided, and the cylinder head is provided with an ignition coil 12 for driving an ignition plug for generating a spark in the cylinder. The exhaust manifold 13 is provided with an air-fuel ratio sensor 14 and a catalyst (not shown). Note that only one or both of the intake VVT 10 and the exhaust VVT 11 may be provided.

  Ignition S / W (hereinafter referred to as IG−) which is a detection signal from each sensor described above, the crank angle sensor 15 for detecting the crank angle and the engine speed, and a detection signal from another sensor (not shown) and an engine start switch (S / W). As information indicating the operating state of the engine 1 including information such as S / W), an electronic control unit (Electronic Control Unit, hereinafter referred to as an ECU) 20 including a microcomputer and an interface circuit is input. .

  The ECU 20 calculates a target torque from various input data, and calculates a target intake air flow rate that achieves the calculated target torque. Then, a target effective opening area of the electronically controlled throttle 4 is calculated by a method described later so as to achieve the target intake air flow rate, and the target throttle opening is obtained. Note that, as the atmospheric pressure necessary for calculating the target effective opening area, an atmospheric pressure estimated value obtained by executing processing in an atmospheric pressure estimating means described later is used. Then, the opening degree of the electronic control throttle 4 is controlled so as to achieve the target throttle opening degree. At the same time, command values for various actuators including the injector 9, the intake VVT 10, the exhaust VVT 11, and the ignition coil 12 are also calculated.

Next, in FIG. 2, the ECU 20 includes an AFS 2 as an operating state detection means, an intake air temperature sensor 3, a throttle opening sensor 5, a pressure sensor 8, an air-fuel ratio sensor 14, a crank angle sensor 15, an IG-S / W 16, 1 and other various sensors 17 not shown in FIG. 1 are input, and an electronic control throttle 4 as a means for controlling the engine 1, an injector 9, an intake VVT 10, an exhaust VVT 11, an ignition coil 12, and FIG. Instruction values for other various actuators 18 not shown are output.

  The ECU 20 performs all the processes related to engine control. Here, an outline of throttle control means and atmospheric pressure estimation means related to the present embodiment will be described. The actual intake air flow rate Qa (estimated from the intake manifold pressure Pb in the case of the S / D method) and the intake air temperature Ta (the intake air temperature sensor is provided in the intake manifold) detected by the AFS2, the intake air temperature sensor 3, and the pressure sensor 8, respectively. The target air-fuel ratio is calculated by the target air-fuel ratio calculating means 21 from the charging efficiency obtained from the use of the air temperature as a substitute for the atmospheric temperature and the engine speed Ne obtained from the crank angle sensor 15. Next, the fuel correction coefficient calculation means 22 calculates a fuel correction coefficient from the target air-fuel ratio calculated above and the air-fuel ratio AF detected by the air-fuel ratio sensor 14. Subsequently, the intake flow correction coefficient is calculated by the intake flow correction coefficient calculation means 23 based on the calculated fuel correction coefficient. Subsequently, the corrected intake air flow rate Qatm used for atmospheric pressure estimation is calculated by the intake air flow rate correction means 24 using the calculated intake air flow rate correction coefficient.

  The actual effective opening area of the electronically controlled throttle 4 (hereinafter referred to as the actual effective opening area) by the effective opening area calculating means 25 from the corrected intake air flow rate Qatm, the intake manifold pressure Pb, the intake air temperature Ta, and the atmospheric pressure estimated value Pa described later. .) CAt is determined.

  Next, the throttle opening learning value calculation means 26 calculates the actual effective opening area CAt calculated above, the actual throttle opening θ detected by the throttle opening sensor 5, and the preset effective opening area. A throttle opening learning value is calculated from the throttle opening relation map. Subsequently, the variation calculating means 27 uses the actual effective opening area CAt, the actual throttle opening θ, and the effective opening area corrected by the throttle opening learning value and the relationship map between the throttle opening and the actual effective opening. A variation amount of the actual throttle opening θ and the learning-corrected throttle opening θ ′ with respect to the area CAt or the actual effective opening area CAt and the learning-corrected effective opening area CAt ′ with respect to the actual throttle opening θ is calculated. Then, the variation range determination unit 28 determines whether the variation amount is within a predetermined range. Further, the learning upper / lower limit determining means 29 determines whether the relationship between the actual effective opening area CAt and the actual throttle opening θ is within a predetermined learning value range.

  Subsequently, the learning upper / lower limit determining means 29 determines that the relationship between the actual effective opening area CAt and the actual throttle opening θ is outside the predetermined learning value range, and the variation range determining means 28 determines that the variation amount is a predetermined value. If it is determined that the pressure is out of the range, the atmospheric pressure estimated value updating unit 30 updates the atmospheric pressure estimated value Pa. Note that the intake manifold pressure is used as the atmospheric pressure estimated value Pa after the IG-S / W 16 is turned on and before the engine is started.

  The target throttle opening calculation means 31 calculates the target throttle opening using the updated estimated atmospheric pressure Pa and other information. The electronic control throttle 4 is controlled by the target throttle opening calculated by the target throttle opening calculating means 31. The above is the outline of the processing of the throttle control means and the atmospheric pressure estimation means performed by the ECU 20. Here, the target air-fuel ratio calculating means 21, the fuel correction coefficient calculating means 22, the intake flow rate correction coefficient calculating means 23, the intake flow rate correcting means 24, the effective opening area calculating means 25, and the throttle opening learning value calculating means 26 are used to control the throttle. The variation calculating unit 27, the variation range determining unit 28, the learning upper and lower limit determining unit 29, the atmospheric pressure estimated value updating unit 30, and the target throttle opening calculating unit 31 constitute an atmospheric pressure estimating unit.

  Next, the flowchart shown in FIG. 3 is executed in the processing up to the atmospheric pressure estimated value updating means 30 performed in the ECU 20 in the calculation processing at every predetermined timing (for example, main processing every 10 ms and interruption processing every BTDC 75 deg CA). Details will be described with reference to FIG.

  In step S301 in FIG. 3, it is determined whether IG-S / W16 is on and the engine is stalled. If Yes, the process proceeds to step S302, and the atmospheric pressure is calculated by substituting the intake manifold pressure Pb for the atmospheric pressure estimated value Pa. The estimated value Pa is updated and the process ends. If the determination in step S301 is No, it is determined that the engine 1 is in operation and the process proceeds to step S303.

  As described above, when the IG-S / W 16 is on and the atmospheric pressure estimated value Pa is updated when the engine is stalled, the atmospheric pressure changes (for example, movement due to transportation) regardless of the traveling of the host vehicle. Can respond to changes in atmospheric pressure.

  Next, in step S303, the actual effective opening area CAt of the electronic control throttle 4 is calculated. This calculation method is basically the same as the method shown in the application of Japanese Patent Application No. 2014-23903, but the basic equations of fluid dynamics used here will be described. A so-called throttle flow meter volume flow rate calculation formula (in the case of a compressible fluid) is expressed by the following formula.

Here, the intake air flow rate is Qa [L / s], the sound speed of the atmosphere is αa [m / s], the effective opening area of the electronic control throttle 4 is CAt [cm ² ], the intake manifold pressure is Pb [kPa], and the atmospheric pressure Is Pa [kPa], and the specific heat ratio is κ. Here, if the dimensionless flow rate σ is defined by the following equation (2), the equation (1) can be simply written as the equation (3).

  The sound velocity αa [m / s] in the atmosphere is expressed by the following equation (4), where R [kJ / (kg · K)] is the gas constant and Ta [K] is the atmospheric temperature.

  Here, when the actual intake air flow rate Qa, the atmospheric sound velocity αa, and the dimensionless flow rate σ are given, the actual effective opening area CAt of the electronic control throttle 4 is the following (5) It can be calculated by a formula.

  As described above, the actual effective opening area CAt of the electronically controlled throttle 4 is obtained if the actual intake air flow rate Qa, the atmospheric sound velocity αa, and the dimensionless flow rate σ are given. Here, the actual intake air flow rate Qa actually used for the calculation uses the corrected intake air flow rate Qatm. The corrected intake air flow rate Qatm is calculated according to the flowchart of FIG.

  In the flowchart of FIG. 4, first, in step S401, a target air-fuel ratio is obtained from the engine speed obtained from the crank angle sensor 15 and the charging efficiency (or intake manifold pressure Pb) obtained from the actual intake air flow rate Qa. In step S402, a fuel correction coefficient is calculated from the target air-fuel ratio and the air-fuel ratio AF calculated from the air-fuel ratio sensor 14. Subsequently, an intake flow rate correction coefficient is calculated based on the fuel correction coefficient in step S403.

  In general, the fuel correction coefficient is calculated as a fuel ratio that is excessive or insufficient with respect to the target air-fuel ratio, and is stored as a coefficient. For example, when the target air-fuel ratio is 14.7 and the air-fuel ratio AF obtained by the air-fuel ratio sensor 14 is 13.5, the fuel correction coefficient is 13.5 / 14.7 = 0.918. Since the fuel amount is calculated from the intake flow rate calculated from AFS2, the true intake flow rate is 0.918 times the detected intake flow rate. Therefore, the intake air flow rate correction coefficient is 0.918. In general, the fuel correction coefficient is always calculated, and there is a concern that if the value is used as it is, the sensitivity is high and overcorrection is caused. Therefore, it is desirable to use a filter or the like for the fuel correction coefficient, to use it as an average value, to perform zoning according to the operating state, and to store the correction coefficient. Finally, in step S404, the corrected intake air flow rate Qatm is calculated using the intake air flow rate correction coefficient. As described above, the atmospheric pressure can be estimated using a more accurate intake flow rate even when the AFS 2 varies.

  Returning to FIG. 3, the throttle opening learning value is calculated in step S304. A method for calculating the throttle opening learning value will be described later. Subsequently, in step S305, the error variation of the throttle opening is calculated. The error variation of the throttle opening is calculated according to the flowchart shown in FIG.

  In the flowchart of FIG. 5, first, in step S501, the actual effective opening area CAt calculated in step S303, a preset relationship map between the effective opening area and the throttle opening, and the throttle opening learning at the previous processing timing. From this value, the current throttle opening learning value is calculated, and the post-learning throttle opening θ ′ with respect to the actual effective opening area CAt is calculated. For example, as shown in FIG. 6, when the vertical axis is the throttle opening and the horizontal axis is the effective opening area, if the relationship map between the preset effective opening area and the throttle opening is a solid line, the throttle opening learning value The relationship between the effective opening area corrected in step 1 and the throttle opening is expressed as a broken line. Here, if the actual effective opening area calculated in step S303 is CAt1, the post-learning throttle opening θ ′ is obtained as T1.

In subsequent step S502, the actual throttle opening theta and calculates a throttle opening error from the learning after the throttle opening theta ', the variance S ² throttle opening error variation of the throttle opening in step S503 assuming a normal distribution Calculated as error variation in degrees. The variance S ² is defined by the following equation (6) in the case of a sample composed of N pieces of data (x1, x2,..., Xn).

Thus, the variance S ² is a mean square error of the mean value and the respective data. In the first embodiment, a learning value obtained from past data is used as an average value, and the square of the error between each data and the learning value is converted to a variance S ² by performing a smoothing process using a primary filter. The corresponding value. Specifically, it calculates with the following (7) Formula and (8) Formula.

  Here, Ts is the square of the throttle opening error, Tg is the variance of the throttle opening error, T2 is the actual throttle opening θ detected by the throttle opening sensor 5, and Kg is a pre-adjusted value with the filter coefficient. Use. Other than the primary filter value, for example, a moving average value may be used. n indicates the current value, and n-1 indicates the previous value.

  As described above, assuming that the error variation of the throttle opening is a normal distribution, the variance can be used for the error variation of the throttle opening, and the variation width can be easily estimated. This completes the error variation calculation of the throttle opening. Although the variance is used here, a standard deviation that is the square root of the variance may be used.

  Returning to the description of the flowchart of FIG. 3, it is determined whether or not the pressure ratio is smaller than the predetermined value A in step S <b> 306. Here, the pressure ratio is a pressure ratio before and after the electronic control throttle 4, and specifically, the intake manifold pressure Pb / the atmospheric pressure estimated value Pa. This pressure ratio is obtained by a pressure ratio calculation means (not shown), and the predetermined value A is set to a value close to 1, for example, 0.95. If the pressure ratio is closer to 1, the sensitivity of the dimensionless flow rate σ is increased, and the error of the throttle opening learning value may be increased, which is excluded.

If the determination in step S306 is Yes, the process proceeds to step S307, and if No, the process proceeds to step S312. In step S312, the previous atmospheric pressure estimated value Pa is set as the atmospheric pressure estimated value Pa, and the process ends. Here, if the determination in step S306 is No, step S3
Prior to proceeding to step 12, a conventional method (for example, the method of Patent Document 1) may be used in combination. That is, when the actual throttle opening θ is larger than the predetermined value or when the intake manifold pressure Pb> the atmospheric pressure estimated value Pa, the process may proceed to step S302, and when it is less, the process may proceed to step S312.

In step S307, the dispersion S ² is the error variance of the throttle opening degree calculated in step S305 determines if larger than the predetermined value B. If the determination in step S307 is Yes, the process proceeds to step S308, and if No, the process proceeds to step S312. In step S312, the previous atmospheric pressure estimated value Pa is set as the atmospheric pressure estimated value Pa, and the process ends.

  Next, in step S308, it is determined whether the actual throttle opening T2 (= θ) with respect to the actual effective opening area CAt1 is smaller than the throttle opening learning lower limit. If the determination in step S308 is yes, the process proceeds to step S309, and if no, the process proceeds to step S310.

  As shown in FIG. 7, when the vertical axis is the throttle opening and the horizontal axis is the effective opening area, the relationship map between the preset effective opening area and the throttle opening is a solid line, and the throttle opening learning lower limit value is a broken line. The throttle opening learning upper limit value is represented by a one-dot chain line. The learning upper and lower limit values are set in advance in consideration of variation in the throttle device difference. In FIG. 7, if the intersection of the actual effective opening area CAt1 calculated in step S303 and the actual throttle opening T2 (= θ) obtained from the throttle opening sensor 5 is lower than the throttle opening learning lower limit T3. Yes. The intersection shown in FIG. 7 is No because it is above the throttle opening learning lower limit T3.

  In step S309, a predetermined value Ptg_up is added from the previous atmospheric pressure estimated value Pa, and the process is terminated as the current atmospheric pressure estimated value Pa. If the intersection is smaller than the throttle opening learning lower limit value T3, it is considered that the actual atmospheric pressure is larger than the estimated atmospheric pressure Pa, not the deviation due to the variation in the throttle machine difference, so the estimated atmospheric pressure Pa is updated to the addition side. . The predetermined value Ptg_up is preferably set to a value of 1 [kPa] or less in order to avoid a sudden change in the estimated atmospheric pressure Pa.

In step S310, it is determined whether the throttle opening is larger than a throttle opening learning upper limit T4. If the determination in step S310 is yes, the process proceeds to step S311, where the predetermined value Ptg_down is subtracted from the previous atmospheric pressure estimated value Pa, and the process is terminated as the current atmospheric pressure estimated value Pa. The throttle opening learning upper limit T4 is set in advance in consideration of variations in the throttle device. If the throttle opening learning value is larger than the throttle opening learning upper limit value T4, it is considered that the actual atmospheric pressure is smaller than the atmospheric pressure estimation value Pa, not the deviation due to the throttle machine difference variation. Update to the subtraction side. The predetermined value Ptg_down is preferably set to a value of 1 [kPa] or less in order to avoid a sudden change in the estimated atmospheric pressure Pa. If the determination in step S310 is No, it is determined that the estimated atmospheric pressure value Pa is correct, so the process proceeds to step S312, and the process is terminated with the estimated atmospheric pressure value Pa as the previous estimated atmospheric pressure value Pa.
The atmospheric pressure estimated value Pa is updated by the above processing.

  Next, the calculation of the throttle opening learning value in step S304 will be described in detail. This calculation is executed by the throttle opening learning value calculation means 26, and is the same as the method shown in the application of Japanese Patent Application No. 2014-23903. Here, a method of realizing the throttle opening learning value calculation means 26 using the theoretical formulas shown in the above formulas (1) to (5) will be described.

8 and 9 are control block diagrams showing details of the throttle opening learning value calculation means 26. FIG. First, the outline of throttle control and throttle opening learning of the throttle opening learning value calculating means 26 will be described with reference to the control block diagram of FIG.

  In block 801, an engine output index such as a target torque is calculated from various input data such as the accelerator opening, and a target cylinder intake air flow rate necessary to achieve the calculated engine output index is calculated. Then, a target intake air flow rate Qa * passing through the throttle is calculated based on the target cylinder intake air flow rate. In the subsequent block 802, the target effective opening area CAt * is used to achieve the target intake air flow rate Qa * from the target intake air flow rate Qa *, the atmospheric sound speed αa, and the dimensionless flow rate σ using the equation (5). Calculated as the target effective opening area CAt *. Thus, since the target effective opening area CAt * is calculated based on the flow rate calculation formula of the throttle type flow meter, it is good even when the operating state of the engine 1 changes due to changes in environmental conditions or the introduction of EGR. The target effective opening area CAt * for achieving the target intake air flow rate Qa * can be calculated.

  By the way, the atmospheric sound speed αa required for the calculation of the block 802 requires a large calculation load to be calculated by the ECU 20 using the equation (4). Is calculated and stored as a map with the intake air temperature Ta as an axis, and the air sound velocity αa is calculated using the intake air temperature Ta in block 803 before the calculation in block 802.

  Further, the dimensionless flow rate σ required for the calculation in the block 802 is not practical to calculate with the ECU 20 using the equation (2) because the calculation load becomes enormous. Therefore, as in block 804, in order to suppress the calculation load on the ECU 20, a theoretical value of the dimensionless flow rate is calculated in advance and stored as a map with the pressure ratio Pb / Pa between the intake manifold pressure Pb and the atmospheric pressure Pa as an axis. The pressure ratio Pb / Pa between the intake manifold pressure Pb and the atmospheric pressure Pa is calculated before the calculation in the block 802, and the dimensionless flow rate σ is calculated using the pressure ratio Pb / Pa calculated in the block 804. .

  Incidentally, it is generally known that when the pressure ratio Pb / Pa is equal to or less than a predetermined value E (about 0.528 in the case of air), the air flow rate through the electronic control throttle 4 is saturated (so-called choke). . It is also known that when this choke occurs, the dimensionless flow rate σ calculated by the equation (2) becomes a constant value. Therefore, when the pressure ratio Pb / Pa between the intake manifold pressure Pb and the atmospheric pressure Pa is equal to or smaller than the predetermined value E, the map value of the block 804 is a constant value corresponding to the predetermined value E (in the case of air, about 0.5787). By doing so, it is possible to cope with the case where choke occurs.

  In addition, the dimensionless flow rate σ may increase the influence of the vibration of the intake manifold pressure Pb due to the intake air pulsation when the pressure ratio Pb / Pa increases to some extent. Therefore, when the pressure ratio Pb / Pa is greater than or equal to a predetermined value Pr (for example, about 0.95), the map value of the block 804 is handled as a constant value (for example, about 0.26) corresponding to the predetermined value Pr. Thus, the influence of the intake air pulsation can be reduced and the throttle controllability can be secured. If the peak value of the intake manifold pressure Pb is larger than the atmospheric pressure Pa, it is considered that air flowing back through the electronic control throttle 4 is generated by pressure vibration in the intake manifold. In this case, the block 804 The map value may be treated as a constant value (for example, about 0.26) corresponding to the predetermined value Pr.

As described above, the target throttle opening TP * is calculated in block 805 using the target effective opening area CAt * calculated in block 802. At that time, the relationship between the actual effective opening area CAt calculated by the equation (5) and the throttle opening TP is detected in advance using the actual intake air flow rate Qa, and the effective opening area CAt and the throttle opening TP are 1: 1. A corresponding effective opening area and throttle opening relationship map is stored, and by using this map, the target throttle opening degree TP * can be calculated from the target effective opening area CAt *.

  As described above, when the electronic control throttle 4 is controlled based on the calculated target throttle opening TP *, the target intake air flow rate Qa * and the actual intake air flow rate caused by variations in the throttle body and various sensors and various estimation errors. A method for calculating the throttle opening learning value TPLRN so as to reduce the error of Qa will be described below.

  In order to calculate the throttle opening learning value TPLRN, in block 806, the actual effective opening area CAti used for learning is calculated from the actual intake air flow rate Qa, the atmospheric sound velocity αa, and the dimensionless flow rate σ. In the subsequent block 807, the learning throttle opening TPi is calculated from the actual effective opening area CAti using the same map as in the block 805. In block 808, a deviation ΔTP (= TP * −TPi) between the target throttle opening TP * and the learning throttle opening TPi is calculated as a throttle opening learning basic value. In block 809, ΔTP is integrated. The throttle opening learning value TPLRN is calculated and stored. The storage processing of the throttle opening learning value TPLRN in block 809 will be described later in detail.

  As described above, the calculated target throttle opening TP * and the throttle opening learning value TPLRN are added in block 810 to finally calculate the learning corrected target throttle opening TPLRN * for driving the electronic control throttle 4.

  As described above, the throttle opening learning value calculation means 26 calculates the throttle opening learning value TPLRN based on the throttle opening learning basic value ΔTP (deviation between the target throttle opening TP * and the learning throttle opening TPi). Then, the throttle opening TP is controlled by using the target throttle opening TPLRN * after learning correction in which the target throttle opening TP * is corrected by the throttle opening learning value TPLRN.

  Hereinafter, the learning function of throttle opening control will be specifically described with reference to FIG. FIG. 10 is an explanatory diagram schematically showing a method of calculating the throttle opening learning basic value ΔTP. Here, assuming that the throttle opening TP and the effective opening area CAt have a one-to-one correspondence, if there is an error between the target intake air flow rate Qa * and the actual intake air flow rate Qa, the target intake There is also an error between the target effective opening area CAt * calculated from the air flow rate Qa * and the actual effective opening area CAti calculated from the actual intake air flow rate Qa.

  For example, as shown in FIG. 10, a relationship map between the effective opening area CAt and the throttle opening TP used for controlling the throttle opening TP (hereinafter referred to as CAt-TP map, used in blocks 805 and 807, see broken line) )) And the actual effective opening area and the actual throttle opening that are estimated and calculated including variations in the throttle body of the engine 1 that is currently controlled, and variations in various sensors that detect intake manifold pressure Pb, intake air temperature Ta, and the like. (Hereinafter referred to as the actual CAt-TP relationship, see the solid line) is considered (the variation in AFS2 has been corrected by the corrected intake air flow rate Qatm).

  At this time, the relationship between the target effective opening area CAt * and the target throttle opening TP * is indicated by a point a on the CAt-TP map (broken line) in FIG. However, as shown in FIG. 10, if there is an error between the CAt-TP map (broken line) and the actual CAt-TP relationship (solid line), the actual CAt-TP relationship corresponding to the target throttle opening TP * ( The actual effective opening area CAti at the point b on the solid line) is different from the target effective opening area CAt *, and the actual intake air flow rate Qa obtained when the throttle opening TP is controlled to the target throttle opening TP * is the target intake opening. It does not agree with the air flow rate Qa *. The actual intake air flow rate Qa used for the calculation at this time may be the corrected intake air flow rate Qatm obtained in FIG.

  Therefore, in order to calculate a learning value for correcting this error, the actual effective opening area CAti is calculated based on the actual intake air flow rate Qa detected when the target throttle opening TP * is controlled. The relationship between the actual effective opening area CAti and the target throttle opening TP * is indicated by a point b on the curve of the actual CAt-TP relationship (solid line) in FIG.

  In FIG. 10, in order to achieve the target effective opening area CAt * (target intake air flow rate Qa *), the throttle opening TP is controlled to a point d on the curve of the actual CAt-TP relationship (solid line). Therefore, the difference ΔTP between the points a and d needs to be calculated as the throttle opening learning basic value. At this time, as shown in FIG. 10, it is assumed that the CAt-TP map (broken line) and the actual CAt-TP relationship (solid line) are locally substantially parallel, and the target throttle opening degree Based on the actual effective opening area CAti calculated from the actual intake air flow rate Qa when controlled to TP *, the learning throttle opening TPi is calculated using a CAt-TP map (broken line).

  The relationship between the learning throttle opening TPi calculated here and the actual effective opening area CAti is indicated by a point c on the CAt-TP map (broken line) in FIG. Accordingly, the throttle opening learning basic value ΔTP (= TP * −TPi) indicated by the difference between the points b and c is substantially equal to the throttle opening learning basic value between the points a and d. Can be considered. The throttle opening learning basic value ΔTP multiplied by a gain is integrated to obtain the throttle opening learning value TPLRN. The learning corrected target throttle calculated by adding the throttle opening learning value TPLRN to the target throttle opening TP *. By controlling the throttle opening TP based on the opening TPLRN *, the error between the target intake air flow rate Qa * and the actual intake air flow rate Qa is reduced.

  In this way, when calculating the throttle opening TP for obtaining the target intake air flow rate Qa *, the target intake can be satisfactorily taken into account for variations in the throttle body and various sensors and errors in various estimation calculations. The relationship between the effective opening area CAt and the throttle opening TP can be learned and corrected so that the air flow rate Qa * can be achieved. At this time, if the error between the CAt-TP map (broken line) and the actual CAt-TP relationship (solid line) is substantially constant (substantially parallel), the throttle opening learning value TPLRN is independently used as feedback control. Even when it is used, it can be controlled well in the entire operation region.

  By the way, for example, as shown in FIG. 11, when the CAt-TP map (broken line) crosses the actual CAt-TP relationship (solid line), or the error of the CAt-TP map (dashed line) is constant. If the throttle opening learning value TPLRN is used alone when it is not (parallel), problems such as follow-up delay and overshoot may occur during transient operation.

  Therefore, in order to deal with such a case, as shown in FIG. 9, the throttle opening learning basic value ΔTP is used as a real-time learning value TPR used as feedback control, and the CAt axis of the CAt-TP map (FIG. 10, FIG. It is desirable to distribute and store a long-time learning value TPL to be stored for each learning region corresponding to (11 horizontal axis) and calculate a throttle opening learning value TPLRN based on them. Thereby, the sum of the value on the CAt-TP map and the long time learning value TPL can be brought close to the actual CAt-TP relationship. Further, by using the real-time learning value TPR together, an instantaneous error can be absorbed by feedback control. Hereinafter, the calculation and storage method of the throttle opening learning value will be described in detail with reference to the explanatory diagrams of FIGS. 12 and 13 together with the functional block diagram of FIG.

In FIG. 9, a distribution process of the throttle opening learning basic value ΔTP is performed by the block 901, and is distributed to the real time learning value TPR and the long time learning value TPL at a predetermined ratio. When the predetermined reset condition is satisfied, the switching unit 901a inputs “0” to the block 902 for calculating the real-time learning value, and when the predetermined update prohibition condition is satisfied,
When the previous real-time learning value TPR (n-1) is input and the reset condition or update prohibition condition for the real-time learning value TPR is not satisfied, the throttle opening learning basic value ΔTP after distribution is input. Therefore, in block 902, the final real-time learning value TPR is calculated based on the throttle opening learning basic value ΔTP after distribution when the reset condition of the real-time learning value TPR and the update prohibition condition described later are not satisfied.

  When the predetermined update prohibition condition is satisfied, the switching unit 901b inputs the previous long-time learning value TPL (n−1) to the block 903, and when the update prohibition condition for the long-time learning value TPL is not satisfied. Inputs the throttle opening learning basic value ΔTP after distribution. Therefore, in block 903, when the update prohibition condition for the long time learning value TPL is not established, the learning is performed for each learning region corresponding to the CAt axis of the CAt-TP map based on the throttle opening learning basic value ΔTP after distribution. The final long time learning value TPL is calculated.

  In addition, as a specific example of the update prohibition condition in the switching units 901a and 901b, when the pressure ratio Pb / Pa between the intake manifold pressure Pb and the atmospheric pressure Pa indicates a predetermined value F or more, or the peak value of the intake manifold pressure Pb is larger. When the pressure is greater than the atmospheric pressure, an error occurs in the calculation of equation (2), so that the updating of the real time learning value TPR and the long time learning value TPL can be prohibited.

  Further, as a specific example of the reset condition in the switching unit 901a, in the period in which the elapsed time after the time change rate dQa * / dt of the target intake air flow rate Qa * reaches the predetermined value G or more is within the predetermined value H. The real time learning value TPR may be reset. This condition corresponds to a case where transient operation is detected, but erroneous learning can be suppressed by using it as a condition for prohibiting update of the long-time learning value TPL.

  In block 904, the long time learning value TPL is limited so that the CAt-TP map and the actual CAt-TP relationship after correction by adding the long time learning value TPL monotonically increase. This is a process for suppressing erroneous learning, and is a process for keeping the relationship between the throttle opening TP and the intake air flow rate Qa monotonously increasing. In block 905, the long time learning value TPL obtained through the monotonous increase processing is stored for each learning region. In block 906, the real time learning value TPR and the long time learning value TPL are added to calculate the throttle opening learning value TPLRN.

  In block 905, the long time learning value TPL is stored in the backup memory. That is, when the engine 1 is stopped or the ECU 20 is powered off, the real-time learning value TPR is reset, but the long-time learning value TPL is held in the backup memory.

  Next, the calculation process for each learning region of the long time learning value TPL shown in FIG. 9 will be specifically described with reference to FIGS. 12 and 13. 12 and 13 are explanatory diagrams schematically showing the storage process and the monotonic increase process of the long time learning value TPL in the first embodiment. In FIG. 10, the throttle opening learning basic value ΔTP is a difference between the point b and the point c, but this is also applied as a learning value between the point a and the point d. Here, consider a case where the throttle opening learning basic value ΔTP is distributed and stored, for example, for each learning region corresponding one-to-one with respect to the CAt axis of the CAt-TP map. At this time, as shown in FIG. 10, at least one of the learning region corresponding to the CAt axis before and after the target effective opening area CAt * and the learning region corresponding to the CAt axis before and after the actual effective opening area CAti is long. It can be stored as a time learning value TPL.

The long time learning value TPL stored in the learning region corresponding to each CAt axis is added with a predetermined value based on the throttle opening learning basic value ΔTP to the previous long time learning value TPL (n−1). Alternatively, a value corresponding to a ratio from the predetermined value to the CAt axis before and after the target effective opening area CAt * and the actual effective opening area CAti can be calculated and added. Further, if the long time learning value TPL is stored in both the target effective opening area CAt * and the actual effective opening area CAti, the convergence time of the long time learning value TPL can be shortened.

  In this way, when the long-time learning value TPL is calculated, the learning is possible only when the update prohibition condition described later is not established, so that learning is actually performed only in the normal operation range. In general, since the throttle opening TP and the intake air flow rate Qa are in a monotonically increasing relationship, the relationship between the effective opening area CAt and the throttle opening TP needs to be monotonically increasing.

  However, when learning is performed locally, the sum (dashed line) of the value of the CAt-TP map (solid line) and the long-time learning value TPL monotonously increases as shown by the broken line and broken line frame in FIG. It may happen that this is not the case. In this case, for example, the target throttle opening TPLRN * after learning correction decreases although the target intake air flow rate Qa * is increased, so that the output of the engine 1 is reduced or the throttle opening learning value TPLRN is erroneously learned. Problems arise.

  Therefore, in the block 904, as indicated by the dotted line and the dotted line frame in FIG. 13, the long value is set so that the sum of the CAt-TP map (solid line) and the long time learning value TPL (see the dotted line) monotonically increases. The long time learning value TPL is limited for each learning region of the time learning value TPL. As a result, erroneous learning or malfunction of the throttle opening learning value TPLRN can be prevented. By doing so, the throttle opening learning value calculation means 26 can be realized, and the relationship between the throttle opening TP and the effective opening area CAt can be learned.

  As described above, according to the control apparatus for an internal combustion engine according to the first embodiment, the intake flow rate correction coefficient is calculated based on the fuel correction coefficient in order to absorb variations in the output of the AFS 2, and the intake flow rate is corrected. Then, the effective opening area is calculated using the corrected intake flow rate, the throttle opening learning value is calculated from the calculated effective opening area and the throttle opening, and the relationship between the throttle opening and the effective opening area with respect to the variation in the throttle machine. The atmospheric pressure estimated value Pa is updated using the statistical variation of the deviation between the throttle opening and the actual throttle opening in consideration of the throttle opening learning value. Thereby, the estimation of the atmospheric pressure can be accurately estimated regardless of the machine difference variation of the electronic control throttle 4.

Embodiment 2. FIG.
Next, a control apparatus for an internal combustion engine according to Embodiment 2 of the present invention will be described in detail. Here, the description of the same part as that of the first embodiment (the part corresponding to FIGS. 1, 2, and 8 to 13) is omitted. The difference from the first embodiment is that the first embodiment estimates the atmospheric pressure based on the variation amount of the actual throttle opening θ and the corrected throttle opening θ ′ with respect to the actual effective opening area CAt. In the second embodiment, the atmospheric pressure is estimated based on the variation amount of the actual effective opening area CAt with respect to the actual throttle opening θ and the learning-corrected effective opening area CAt ′.

  FIG. 14 is a flowchart showing the atmospheric pressure estimation process of the control device for an internal combustion engine according to the second embodiment. The process up to the atmospheric pressure estimated value update unit 30 performed by the ECU 20 is performed at predetermined timing (for example, It is explanatory drawing implemented in the main process for every 10 ms, and the interruption process for every BTDC75degCA).

The processing from step S1401 to step S1404 in the flowchart shown in FIG. 14 is the same as the processing from step S301 to step S304 in FIG. The actual intake air flow rate Qa used for calculating the effective opening area in step S1401 is the corrected intake air flow rate Qatm described in the first embodiment, and thus the description thereof is omitted. Further, the calculation of the throttle opening learning value in step S1404 (executed by the throttle opening learning value calculation means 26) is basically the same as the content described in the first embodiment, and therefore will be omitted.

Next, step S1405 and subsequent steps will be described.
In step S1405, the error variation of the effective opening area is calculated. The error variation of the effective opening area is calculated by the flowchart shown in FIG.

  In FIG. 15, in step S1501, the actual throttle opening θ obtained from the throttle opening sensor 5, the relationship map between the preset effective opening area and the throttle opening, and the effective opening area learning at the previous processing timing. From this value, the current effective opening area learning value is calculated, and the corrected effective opening area CAt ′ for the actual throttle opening θ is calculated. For example, as shown in FIG. 16, when the vertical axis is the effective opening area and the horizontal axis is the throttle opening, the relationship map between the effective opening area and the throttle opening that is set in advance is a solid line. The corrected value is represented as a broken line. Here, when the actual throttle opening θ is T5, the effective opening area after learning is obtained as CAt2. Note that the actual effective opening area calculated in step S1403 is CAt3.

  Next, in step S1502, an effective aperture area error is calculated from the actual effective aperture area CAt3 and the learned effective aperture area CAt2, and in step S1503, the error variation of the effective effective aperture area is assumed to be a normal distribution. Calculate as In the second embodiment, a learning value obtained from past data is used as an average value, and the square of the error between each data and the learning value is subjected to a smoothing process using a primary filter. To do. Specifically, it calculates with the following (9) Formula and (10) Formula.

  Here, CAts is the square of the effective aperture area error, CAtg is the variance of the effective aperture area error, CAt3 is the actual effective aperture area obtained in step S1303, Kg is the filter coefficient, and a pre-adapted value is used. Other than the primary filter value, for example, a moving average value may be used. n indicates the current value, and n-1 indicates the previous value.

  As described above, assuming that the error variation of the effective aperture area is a normal distribution, the variance can be used for the error variation of the effective aperture area, and the variation width can be easily estimated. Thus, the effective opening area error variation calculation ends. Although the variance is used here, a standard deviation that is the square root of the variance may be used.

  Returning to the flowchart of FIG. 14, it is determined whether or not the pressure ratio is smaller than the predetermined value A in step S1406. If the determination in step S1406 is Yes, the process proceeds to step S1407, and if No, the process proceeds to step S1412. Here, the setting of the predetermined value A is the same as in the first embodiment. In step S1412, the atmospheric pressure estimated value Pa is set as the previous atmospheric pressure estimated value Pa, and the process ends. Here, in the case of No, a conventional method (for example, the method of Patent Document 1) may be used together before proceeding to Step S1412. That is, when the throttle opening θ is larger than the predetermined value or when the intake manifold pressure Pb> the atmospheric pressure estimated value Pa, the process may proceed to step S1402, and when the throttle opening θ is less than the predetermined value, the process may proceed to step S1412.

  In step S1407, it is determined whether the variance, which is the error variation of the effective opening area calculated in step S1405, is greater than a predetermined value C. If the determination in step S1407 is Yes, the process proceeds to step S1408, and if No, the process proceeds to step S1412. In step S1412, the previous atmospheric pressure estimated value Pa is set as the atmospheric pressure estimated value Pa, and the process ends.

  In step S1408, it is determined whether the actual effective opening area is larger than the throttle opening learning upper limit value. If the determination in step S1408 is Yes, the process proceeds to step S1409, and if No, the process proceeds to step S1410. As shown in FIG. 17, when the vertical axis is the effective opening area and the horizontal axis is the throttle opening, the relationship map between the preset effective opening area and the throttle opening is a solid line, and the throttle opening learning lower limit is a broken line. The throttle opening learning upper limit value is represented by a one-dot chain line. The upper and lower limits of throttle opening learning are set in advance in consideration of variations in the throttle machine difference. In FIG. 17, if the intersection of the actual effective opening area CAt3 calculated in step S1403 and the actual throttle opening T5 (= θ) obtained from the throttle opening sensor 5 is higher than the throttle opening learning upper limit CAt5, Yes. It becomes. Since the intersection shown in FIG. 17 is above the throttle opening learning upper limit, the answer is Yes.

  In step S1409, the predetermined value Ptg_up is added to the previous estimated atmospheric pressure value Pa, and the process is terminated as the current estimated atmospheric pressure value Pa. If the intersection is larger than the throttle opening learning upper limit value, it is considered that the actual atmospheric pressure is larger than the atmospheric pressure estimated value Pa, not the deviation due to the throttle machine difference variation, so the atmospheric pressure estimated value Pa is updated to the addition side. The predetermined value Ptg_up is preferably set to a value of 1 [kPa] or less in order to avoid a sudden change in the estimated atmospheric pressure value.

In step S1410, it is determined whether the effective opening area is smaller than the throttle opening learning lower limit CAt4. If YES in step S1410, the process advances to step S1411 to subtract the previous estimated atmospheric pressure value Pa by a predetermined value Ptg_down, and the process ends as the estimated atmospheric pressure value Pa this time. If the throttle opening learning value is smaller than the learning lower limit value, it is considered that the actual atmospheric pressure is smaller than the estimated atmospheric pressure Pa, not the change due to the variation in the throttle machine difference, so the estimated atmospheric pressure Pa is updated to the subtraction side. To do. The predetermined value Ptg_down is preferably set to a value of 1 [kPa] or less in order to avoid a sudden change in estimated atmospheric pressure. If the determination in step S1410 is No, the process proceeds to step S1412. In step S1412, the previous atmospheric pressure estimated value Pa is set as the atmospheric pressure estimated value Pa, and the process ends.
The atmospheric pressure estimated value Pa is updated by the above processing.

  As described above, according to the control apparatus for an internal combustion engine according to the second embodiment, the intake flow rate correction coefficient is calculated based on the fuel correction coefficient in order to absorb variations in the output of the AFS 2, and the intake flow rate is corrected. Then, the effective opening area is calculated using the corrected intake flow rate, the throttle opening learning value is calculated from the calculated effective opening area and the throttle opening, and the relationship between the throttle opening and the effective opening area with respect to the variation in the throttle machine. The atmospheric pressure estimated value Pa is updated using the statistical variation of the deviation between the throttle opening and the actual throttle opening in consideration of the throttle opening learning value. Thereby, the estimation of the atmospheric pressure can be accurately estimated regardless of the machine difference variation of the electronic control throttle 4.

1 engine, 2 air flow sensor, 3 intake temperature sensor, 4 electronic control throttle, 5 throttle opening sensor, 6 surge tank, 7 intake manifold, 8 pressure sensor, 9 injector, 10 intake VVT, 11 exhaust VVT, 12 ignition coil , 13 Exhaust manifold, 14 Air-fuel ratio sensor, 15 Crank angle sensor, 16 IG-S / W, 17 Various sensors, 18 Various actuators, 20 ECU, 21 Target air-fuel ratio calculating means, 22 Fuel correction coefficient calculating means, 23 Intake flow rate Correction coefficient calculating means, 24 intake flow rate correcting means, 25 effective opening area calculating means, 26 throttle opening learning value calculating means, 27 variation calculating means, 28 variation range determining means, 29 learning upper / lower limit determining means, 30 atmospheric pressure estimated value Update means, 31 target slot Torr opening calculation means.

Control apparatus for an internal combustion engine according to the present invention, in the control apparatus for an internal combustion engine having an atmospheric pressure estimating means for estimating an atmospheric pressure to be applied to the calculation of the control parameters of the internal combustion engine, operation for detecting an operating condition of the internal combustion engine a state detecting means, and the target intake air flow rate calculation means for calculating a target intake air flow rate based on an operating state of the internal combustion engine, and the target air-fuel ratio calculating means for calculating a target air-fuel ratio based on an operating state of the internal combustion engine A throttle provided in the intake passage of the internal combustion engine, and a throttle opening for variably controlling the intake amount to the internal combustion engine by changing the effective opening area of the intake passage by controlling the opening of the throttle Control means, throttle opening detection means for detecting the actual opening of the throttle, and intake air flow rate detection for detecting the actual intake air flow rate to the internal combustion engine Stage and a pressure detecting means for detecting the pressure of the internal combustion engine side of the throttle as intake manifold pressure, and intake air temperature detecting means for detecting an intake air temperature of the air side of the throttle, air-fuel ratio for detecting the air-fuel ratio after the combustion a detection means, the air-fuel ratio based on the target air-fuel ratio calculated air-fuel ratio detected by the detecting means at the target air-fuel ratio calculating means, the fuel correction coefficient calculating means for calculating a fuel correction coefficient for correcting the fuel injection amount Fuel injection means for injecting fuel corrected based on the fuel correction coefficient calculated by the fuel correction coefficient calculation means, and intake air flow correction coefficient calculation means for calculating the intake flow correction coefficient based on the fuel correction coefficient And an intake air flow rate correction means for correcting the actual intake air flow rate using the intake air flow rate correction coefficient calculated by the intake air flow rate correction coefficient calculation means, and Effective opening area calculating means for calculating an actual effective opening area corresponding to the actual opening of the throttle based on the atmospheric pressure, the intake air flow corrected by the intake flow correction means, the intake manifold pressure, and the intake air temperature A target throttle opening calculated by the effective opening area calculated by the effective opening area calculating means, the actual opening of the throttle, and a preset relationship map between the effective opening area and the throttle opening. Throttle opening learning value calculating means for calculating, as a throttle opening learning value, a throttle opening learning value obtained by multiplying and integrating a throttle opening learning basic value, which is the difference between the degree and the learning throttle opening, by gain, The estimation means is
The actual effective opening area wherein the actual opening of the throttle, by the relation map of the throttle opening effective opening area and the throttle opening corrected by the learning value, the throttle with respect to the actual effective opening area The actual opening and the throttle opening after learning correction, or the variation calculating means for calculating the error variation between the actual effective opening area and the effective opening area after learning correction with respect to the actual opening of the throttle, and the actual Learning upper and lower limit determination means for determining whether the relationship between the effective opening area of the throttle and the actual opening of the throttle is within a predetermined range based on the preset relationship map between the effective opening area and the throttle opening A variation range determination unit that determines whether or not the error variation calculated by the variation calculation unit is within a predetermined range, and the actual effective Outside the scope relationship of predetermined actual opening of the mouth area throttle and by the error variation adding or subtracting a predetermined value to the previous atmospheric pressure estimated value when was outside the predetermined range, this An atmospheric pressure estimated value updating means for calculating and updating the atmospheric pressure estimated value, calculating a target throttle opening using the atmospheric pressure estimated value updated by the atmospheric pressure estimated value updating means, and opening the throttle The degree is controlled.

In the flowchart of FIG. 4, first, in step S401, a target air-fuel ratio is obtained from the engine speed obtained from the crank angle sensor 15 and the charging efficiency (or intake manifold pressure Pb) obtained from the actual intake air flow rate Qa. Next, in step S402, a fuel correction coefficient is calculated from the target air-fuel ratio and the air-fuel ratio AF detected by the air-fuel ratio sensor 14. Subsequently, an intake flow rate correction coefficient is calculated based on the fuel correction coefficient in step S403.

In general, the fuel correction coefficient is calculated as a fuel ratio that is excessive or insufficient with respect to the target air-fuel ratio, and is stored as a coefficient. For example, when the target air-fuel ratio is 14.7 and the air-fuel ratio AF detected by the air-fuel ratio sensor 14 is 13.5, the fuel correction coefficient is 13.5 / 14.7 = 0.918. Since the fuel amount is calculated from the intake flow rate calculated from AFS2, the true intake flow rate is 0.918 times the detected intake flow rate. Therefore, the intake air flow rate correction coefficient is 0.918. In general, the fuel correction coefficient is always calculated, and there is a concern that if the value is used as it is, the sensitivity is high and overcorrection is caused. Therefore, it is desirable to use a filter or the like for the fuel correction coefficient, to use it as an average value, to perform zoning according to the operating state, and to store the correction coefficient. Finally, in step S404, the corrected intake air flow rate Qatm is calculated using the intake air flow rate correction coefficient. As described above, the atmospheric pressure can be estimated using a more accurate intake flow rate even when the AFS 2 varies.

Claims (9)

In a control device for an internal combustion engine comprising an atmospheric pressure estimation means for estimating an atmospheric pressure to be applied to calculation of a control parameter of the internal combustion engine,
An operating state detecting means for detecting an operating state of the internal combustion engine;
Target intake air flow rate calculating means for calculating a target air flow rate based on the operating state of the internal combustion engine;
Target air-fuel ratio calculating means for calculating a target air-fuel ratio based on the operating state of the internal combustion engine;
A throttle provided in an intake passage of the internal combustion engine;
Throttle opening control means for variably controlling the amount of intake air to the internal combustion engine by changing the effective opening area of the intake passage by controlling the opening of the throttle;
Throttle opening detection means for detecting the actual opening of the throttle;
Intake air flow rate detection means for detecting the actual intake air flow rate to the internal combustion engine;
Pressure detecting means for detecting the pressure on the internal combustion engine side of the throttle as an intake manifold pressure;
An intake air temperature detecting means for detecting an intake air temperature on the atmosphere side of the throttle;
Air-fuel ratio calculating means for detecting the air-fuel ratio after combustion;
Fuel injection amount setting means for setting a fuel injection amount based on the target air flow rate and the target air-fuel ratio;
Fuel for calculating a fuel correction coefficient for correcting the fuel injection amount set by the fuel injection amount setting means based on the air-fuel ratio detected by the air-fuel ratio calculation means and the target air-fuel ratio calculated by the target air-fuel ratio calculation means Correction coefficient calculation means;
Fuel injection means for injecting fuel corrected based on the fuel correction coefficient calculated by the fuel correction coefficient calculation means;
Intake air flow correction coefficient calculating means for calculating an intake flow correction coefficient based on the fuel correction coefficient;
An intake flow rate correction means for correcting the actual intake air flow rate using the intake flow rate correction coefficient calculated by the intake flow rate correction coefficient calculation means;
Based on the estimated atmospheric pressure, the intake air flow corrected by the intake flow correction means, the intake manifold pressure, and the intake air temperature, an effective effective opening area corresponding to the actual opening of the throttle is calculated. Opening area calculating means;
The throttle opening learning value is calculated from the actual effective opening area calculated by the effective opening area calculating means, the actual opening of the throttle, and a preset relationship map between the effective opening area and the throttle opening. Throttle opening learning value calculation means,
The atmospheric pressure estimating means includes
Variation calculating means for calculating an error variation based on a relationship map between the actual effective opening area, the actual opening of the throttle, the effective opening area corrected by the throttle opening learning value, and the throttle opening;
Learning upper and lower limit determination means for determining whether the relationship between the actual effective opening area and the actual opening of the throttle is within a predetermined range with reference to the relationship map between the effective opening area and the throttle opening;
A variation range determination unit that determines whether or not the error variation calculated by the variation calculation unit is within a predetermined range;
Atmospheric pressure estimated value updating means for updating the atmospheric pressure estimated value when the relationship between the actual effective opening area and the actual opening of the throttle is out of a predetermined range and the error variation is out of the predetermined range. And comprising
An atmospheric pressure estimation device for an internal combustion engine, wherein a target throttle opening is calculated using the atmospheric pressure estimated value updated by the atmospheric pressure estimated value updating means, and the throttle opening is controlled. The error variation is a throttle opening corrected with the throttle opening learning value with respect to the actual effective opening area calculated from a relationship map between the effective opening area corrected with the throttle opening learning value and the throttle opening; 2. The control apparatus for an internal combustion engine according to claim 1, wherein the throttle opening error is calculated as a deviation of an actual opening of the throttle.   3. The control apparatus for an internal combustion engine according to claim 2, wherein the error variation is a variance or a standard deviation of the throttle opening error.   When the actual opening of the throttle with respect to the actual effective opening area of the throttle is larger than a preset throttle opening learning upper limit value, the estimated atmospheric pressure is updated to the decreasing side, and the preset throttle opening learning is performed. The control apparatus for an internal combustion engine according to any one of claims 1 to 3, wherein the estimated atmospheric pressure value is updated to an increase side when smaller than the lower limit value.   The error variation is an effective opening area corrected with the throttle opening learning value with respect to an actual opening of the throttle calculated from a relationship map between the effective opening area corrected with the throttle opening learning value and the throttle opening. 2. The control apparatus for an internal combustion engine according to claim 1, wherein the effective opening area error is calculated as a deviation of the actual effective opening area.   The control apparatus for an internal combustion engine according to claim 5, wherein the error variation is a variance or a standard deviation of the effective opening area error.   When the actual effective opening area with respect to the actual opening of the throttle is larger than a preset throttle opening learning upper limit value, the atmospheric pressure estimation value is updated to the increasing side, and from the preset throttle opening learning lower limit value The control apparatus for an internal combustion engine according to any one of claims 1, 5, and 6, wherein when it is small, the estimated atmospheric pressure value is updated to a decreasing side.   The control apparatus for an internal combustion engine according to any one of claims 1 to 7, wherein the atmospheric pressure estimation means sets the intake manifold pressure before starting the engine to an estimated atmospheric pressure value. Pressure ratio calculating means for obtaining a pressure ratio between the intake manifold pressure and the atmospheric pressure estimated value;
9. The internal combustion engine according to claim 1, wherein when the pressure ratio calculated by the pressure ratio calculation means is outside a predetermined range, the update of the atmospheric pressure estimated value is stopped. Control device.