JP5851358B2 - Control device for internal combustion engine - Google Patents

Description

  The present invention relates to a control device for an internal combustion engine provided with an air flow sensor, and more particularly to a control device for an internal combustion engine that can obtain an accurate intake air amount even when pulsation occurs in measured air.

  In recent years, regulations on fuel consumption and exhaust of vehicles such as automobiles are being strengthened, and such regulations tend to become stronger and stronger in the future. The intake air amount is a parameter used for calculating the fuel injection amount, and highly accurate intake air amount detection is indispensable in order to comply with regulations that will become stricter in the future. Since the output result of the air flow sensor affects fuel consumption and exhaust performance, technological development for increasing the intake air amount detection accuracy of the air flow sensor has been actively conducted.

  Currently, a hot-wire airflow sensor is widely used as an airflow sensor capable of measuring the amount of intake air. The detection signal of this airflow sensor changes the voltage value according to the amount of air based on the signal from the heating resistor. In many cases, a voltage signal or a frequency signal that changes the cycle of the output pulse according to the amount of air is used.

  By the way, in a multi-cylinder internal combustion engine, intake pulsation occurs in the intake pipe due to the reciprocating motion of the piston. Therefore, even in a steady state, the detection signal of the hot-wire airflow sensor fluctuates in synchronization with the engine speed and intake pulsation.

  In particular, the hot-wire airflow sensor placed upstream of the throttle valve is susceptible to intake pulsation when the throttle valve is fully opened, and even if the detection signal is smoothed, there is an error relative to the true air amount. Is known to produce An error caused by the intake pulsation is called a pulsation error. For this reason, as disclosed in Japanese Patent Laid-Open No. 2001-5090 (Patent Document 1), a method of correcting the air amount with respect to the intake pulsation has been proposed.

JP 2001-5090 A

  The method of correcting the intake air amount described in Patent Document 1 is a method of calculating the correction amount based on the intake pipe pressure, the throttle valve operation amount, or the engine speed when calculating the intake pulsation amplitude ratio. is there.

  Here, in the hot-wire air flow sensor, the value of the current flowing through the heating resistor arranged in the intake air flow to be measured increases when the amount of intake air is large, and conversely decreases when the amount of intake air is small. A bridge circuit is formed, and a voltage signal or a frequency signal obtained by voltage-frequency conversion is taken out as an air amount signal by a current flowing through the heating resistor.

  Since the hot wire air flow sensor uses the heat balance of the heating resistor, the detection accuracy is affected by the magnitude and frequency of the pulsation when it is affected by the intake pulsation, and the output of the hot wire air flow sensor is particularly high. It has a frequency response characteristic in which response delay occurs in the frequency domain. Therefore, when the output characteristic has a non-linear characteristic, the detected output average value and the true air amount average value do not coincide with each other, and an error occurs. Also, this error tends to increase with larger pulsation and higher frequency.

  The present invention has been made in view of such a problem, and an object of the present invention is to correct an error generated during pulsation due to a response delay of an air flow sensor and accurately calculate an intake air amount. It is to provide a control device.

  In order to achieve the above object, a control device for an internal combustion engine according to the present invention is a control device for an internal combustion engine comprising intake air amount calculation means for calculating an intake air amount based on an output value of an air flow sensor, the intake air being A pulsation amplitude ratio calculating means for calculating a pulsation amplitude ratio from the amount of pulsation amplitude and the average air amount; and a pulsation frequency calculating means for calculating a pulsation frequency resulting from the engine speed, the pulsation amplitude ratio calculating means And a pulsation error calculation means for calculating a pulsation error using the pulsation frequency calculation means, and the intake air amount is corrected based on the pulsation error correction amount calculated by the pulsation error calculation means.

  That is, the feature of the present invention is that the pulsation frequency is obtained from the engine speed, the frequency response correction amount for correcting the frequency response of the hot-wire airflow sensor is obtained from the pulsation frequency, and the pulsation amplitude is obtained from the frequency response correction amount and the airflow sensor output value. The ratio is obtained, and the air flow sensor output value is corrected so as to obtain the final air amount based on the pulsation error correction map composed of the pulsation frequency and the pulsation amplitude ratio.

  According to the present invention, since the air amount can be obtained in consideration of the influence of the intake pulsation over a wide rotation region, the pulsation is accurately calculated regardless of the magnitude or frequency change of the intake pulsation. The error can be reduced.

1 is an overall configuration diagram schematically showing an overall configuration of an internal combustion engine to which an embodiment of a control device for an internal combustion engine according to the present invention is applied. 1 is an overall configuration diagram of an ECU (Engine Control Unit). The block diagram which shows the conventional fuel-injection pulse-width calculation method. The chart which shows the relationship between the voltage of an airflow sensor, and air quantity. The chart which shows the frequency response (low frequency) of an airflow sensor. The chart which shows the frequency response (high frequency) of an airflow sensor. The chart which shows attenuation of the frequency characteristic of an airflow sensor. The chart which shows the influence which attenuation of a voltage signal has on average air volume. The chart which shows the frequency response (small pulsation) of an airflow sensor. The chart which shows the frequency response (large pulsation) of an airflow sensor. The chart which shows the tendency of the pulsation error by frequency difference. The block diagram which shows the intake air amount calculation by pulsation error calculation calculation. Pulsation correction map diagram.

  Hereinafter, an embodiment of a control device for an internal combustion engine according to the present invention will be described in detail with reference to the drawings. FIG. 1 schematically shows the overall configuration of an internal combustion engine to which an embodiment of a control apparatus for an internal combustion engine according to the present invention is applied.

  An internal combustion engine 10 shown in FIG. 1 is a spark ignition type multi-cylinder engine having four cylinders, for example, and includes a cylinder 29 including a cylinder head 29a and a cylinder block 29b, and slides in each cylinder of the cylinder 29. A piston 27 that is freely inserted, and the piston 27 is connected to a crankshaft (not shown) via a connecting rod 28. In addition, a combustion chamber 26 having a ceiling portion with a predetermined shape is defined above the piston 27, and an ignition plug to which a high voltage ignition signal is supplied from the ignition coil 20 to the combustion chamber 26 of each cylinder. 19 is erected.

  The combustion chamber 26 communicates with an intake passage 15 including an air cleaner 11, a throttle valve 13, a collector 16, an intake manifold 17, an intake port 18, and the like, and air necessary for fuel combustion is in the intake passage 15. And is sucked into the combustion chamber 26 of each cylinder via an intake valve 30 that is opened and closed by an intake camshaft 22 disposed at an end of an intake port 18 that is a downstream end of the intake passage 15. It has become. In addition, an injector 21 that injects fuel toward the intake port 18 is provided for each cylinder in the intake manifold 17 of the intake passage 15.

  Further, an air flow sensor 12 for detecting the amount of intake air is disposed downstream of the air cleaner 11 in the intake passage 15. An air-fuel mixture of air sucked through the intake passage 15 and fuel injected from the injector 21 is sucked into the combustion chamber 26 through the intake valve 30 and is spark ignited by the spark plug 19 connected to the ignition coil 20. Is burned by. The exhaust gas after combustion in the combustion chamber 26 is exhausted from the combustion chamber 26 via an exhaust valve 31 that is opened and closed by an exhaust camshaft 23, and is exhausted through an exhaust port, an exhaust manifold, an exhaust pipe and the like (not shown). The gas is discharged into the outside atmosphere through the exhaust passage 32 provided.

Further, on the downstream side of the exhaust passage 32, a three-way catalyst 35 for purifying exhaust gas in which platinum or palladium is applied to a carrier such as alumina or ceria is disposed, and on the upstream side of the catalyst 35, A linear air-fuel ratio sensor 33 having a linear output characteristic with respect to the pre-catalyst air-fuel ratio is disposed, and on the downstream side of the catalyst 35, whether the post-catalyst air-fuel ratio is richer or leaner than stoichiometric (theoretical air-fuel ratio). Is provided with an O ₂ sensor 34 that outputs a switching signal.

  The injector 21 provided for each cylinder of the internal combustion engine 10 is connected to a fuel tank 36. The fuel in the fuel tank 36 is a fuel supply mechanism including a fuel pump 37, a fuel pressure regulator 38, and the like. Thus, the pressure is adjusted to a predetermined fuel pressure and supplied to the injector 21. The injector 21 to which fuel of a predetermined fuel pressure is supplied is driven to open by a fuel injection pulse signal having a duty (pulse width: corresponding to the valve opening time) corresponding to the operating state such as the engine load supplied from the ECU 100, An amount of fuel corresponding to the valve opening time is injected toward the intake port 18.

  The ECU 100 incorporates a microcomputer for performing various controls of the internal combustion engine 10, for example, fuel injection control (air-fuel ratio control) by the injector 21, ignition timing control by the spark plug 19, and the like.

  FIG. 2 shows the overall configuration of the ECU 100. The ECU 100 includes a power supply IC 101 and an LSI 102. A RESET terminal of the LSI 102 is connected to the power supply IC 101 so that a RESET signal controlled by the power supply IC 101 can be transmitted.

  The ECU 100 also includes sensors necessary for controlling the internal combustion engine, such as a crank angle sensor 25 for detecting the engine speed, a water temperature sensor 40 for detecting the cooling water temperature of the internal combustion engine 10, and a throttle valve opening degree. Signals such as a throttle sensor 14 to detect, an air-fuel ratio sensor 33 to detect the oxygen concentration in the exhaust gas, a starter switch 41, and an air flow sensor 12 are input.

  Detection signals from these sensors are input to an LSI (input processing circuit) 102 in the ECU 100 and are detected as an analog input by an A / D converter and detected at a high / low level. It is processed.

  The CPU 103 executes predetermined digital arithmetic processing by a program stored in the CPU, outputs various actuator control signals necessary for control of the internal combustion engine from the arithmetic result, and outputs an LSI (input processing circuit) 102. It has a function of controlling various actuators via an output circuit.

  For example, each injector 21 of the internal combustion engine 10 is detected from the mass flow rate measured from the detection signal of the hot-wire air flow sensor 12, the rotational speed of the internal combustion engine 10 measured from the crank angle sensor 25, and the water temperature sensor 40. Each correction amount including the water temperature and a correction amount corresponding to the air-fuel ratio state detected by the air-fuel ratio sensor 33 are added to calculate the fuel injection amount, and finally output to the injector 21 as a drive pulse width. Similarly, an ignition signal for controlling the energization timing to the ignition coil 20 necessary for combustion of the internal combustion engine, a signal for the electric throttle 13 for controlling the throttle valve opening, and the like.

  Next, the outline of the hot-wire airflow sensor 12 will be described. The hot-wire airflow sensor 12 has a heating resistor arranged in the air flow to be measured as a main component, and the current value flowing through the heating resistor increases when the amount of intake air is large. The bridge circuit is configured to decrease when the amount of air is small, and the amount of air is taken out as a voltage signal by the current flowing through the heating resistor. A voltage signal corresponding to the amount of air is output as a voltage value, and there is also a signal that is converted into a frequency signal by being converted by a voltage-frequency conversion circuit and output.

  FIG. 3 shows a calculation method for obtaining the air amount based on the output signal of the hot-wire airflow sensor 12 according to a conventional method, and this calculation is executed by internal processing of the ECU 100. For example, assuming that the resolution of the A / D converter 104 is 10 bits and the voltage per bit recognized by the CPU 103 is equivalent to 5 mV, the digital value is 200 when A / D conversion is performed on 1.0 V.

  The voltage information Va is given to the air amount conversion table 105. The air amount conversion table 105 has an air amount stored in advance corresponding to the voltage information Va, and is subjected to a search interpolation calculation to be converted into a detected air amount. The Hereinafter, description will be made assuming that the detected air amount indicates the air amount converted by the air amount conversion table 105.

  In addition, although not shown in the figure, when the signal is input as a frequency signal subjected to voltage-frequency conversion, the period of the signal is measured at the port input of the CPU 103, and the value converted from the period or the period to the frequency becomes the input, and the amount of air The conversion table 105 is searched and interpolated from values stored in advance according to the period or frequency, and converted into a detected air amount. The air amount signal Q obtained from the air amount conversion table 105 is then subjected to digital filter processing 106 for the purpose of removing high frequency component noise to calculate the detected air amount Qc.

  In the fuel injection pulse width calculation 107, the detected air amount Qc is divided by the number of revolutions 115 of the internal combustion engine separately calculated from the signal of the crank angle sensor 25 to be equivalent to the amount of air sucked into the cylinder, and each correction calculation is performed. After that, a time Tout for injecting fuel is calculated, and the injector 21 operates to supply the fuel to the internal combustion engine 10.

FIG. 4 shows the relationship between the intake air amount and the output signal of a general hot-wire airflow sensor 12. The output signal voltage is low when the intake air amount is small, and is output when the intake air amount is large. This is a characteristic curve having a nonlinear relationship in which the voltage of the signal increases. The reason why the non-linearity characteristic is used is that the following equation called the King equation is mainly used as the air amount Q when the detection signal from the heating resistor is converted into the air amount.
Ih · Rh = (α + β · √Q) · (Th−Ta)

  Here, Ih is the current value of the heating resistor, Rh is the resistance value of the heating resistor, Th is the surface temperature of the heating resistor, Ta is the temperature of the air, Q is the amount of air, and α and β are constants determined by the specifications of the heating resistor. It is.

  Generally, since the current value Ih of the heating resistor is controlled so that (Th−Ta) becomes constant, the amount of air is detected by converting it to the voltage value V by the voltage drop of the resistor. The value V is a quartic function expression. For this reason, when converting into air quantity, the curvature of a quartic curve, ie, the relationship between output and air quantity becomes nonlinear.

  As for the characteristic curve, since the output of the hot-wire air flow sensor 12 is set in accordance with the required air amount of the internal combustion engine, the relationship between the frequency and the air amount or the relationship between the voltage and the air amount is an inverse characteristic or a linear relationship. However, only the conversion table 105 is changed for the arithmetic processing.

  The frequency characteristics of the hot-wire airflow sensor 12 will be described with reference to FIGS. 5, 6, and 7. Since the hot-wire airflow sensor 12 uses the heat balance of the heating resistor, a delay occurs with respect to the actual change in the air amount. This delay is called response delay. FIG. 5 shows the actual change in the air amount and the output value of the hot-wire airflow sensor 12 when the pulsation frequency is low. When the frequency is low, the output of the hot-wire air flow sensor 12 can follow the actual change in the air amount with little delay.

  On the other hand, when the frequency is increased as shown in FIG. 6, the output of the hot-wire airflow sensor 12 cannot follow the actual change in the air amount and attenuates. This phenomenon becomes more prominent as the frequency becomes higher, and FIG. FIG. 7 shows the frequency characteristics of the hot-wire airflow sensor 12, where the horizontal axis represents frequency and the vertical axis represents gain (dB). When the gain is 0 dB, there is no attenuation, and the waveform is attenuated as the gain becomes negative.

  From the above, it can be seen that the waveform of the hot-wire airflow sensor 12 attenuates as the frequency increases. Here, the influence on the air amount when the waveform is attenuated will be described with reference to FIG. FIG. 8 shows the relationship between voltage and air volume. When the pulsation amplitude of the actual air amount is (A) and the amplitude of the voltage when the air amount at that time is converted into a voltage is (B), the amplitude of the voltage (B) due to the frequency characteristics of the hot-wire airflow sensor 12 Is attenuated to (C), and the amplitude of the air amount when the voltage is converted into the air amount is (D).

Since the actual air volume pulsation is (A), the average air volume at that time is Q _A , but when the waveform attenuated by the frequency response delay of the hot-wire airflow sensor 12 is converted into the air volume, it becomes Q _D. There is a minus error by (Q _A -Q _D ) with respect to the actual air amount. Due to the frequency characteristics of the hot-wire airflow sensor 12, the higher the frequency, the greater the attenuation of the waveform, and the greater the minus error.

  Further, the hot-wire airflow sensor 12 has a property that the minus error becomes larger not only when the frequency is high but also when the pulsation is large. 9 and 10 show the same pulsation frequency. FIG. 9 shows the actual air amount and the output value of the hot-wire air flow sensor 12 when the pulsation is small, and FIG.

  When the pulsation is small as shown in FIG. 9, the hot-wire airflow sensor 12 can follow the actual air amount change, but when the pulsation is large as shown in FIG. Since the change cannot be followed, the waveform is attenuated. As a result, as described above with reference to FIG. 8, a negative error occurs due to the attenuation of the waveform.

By the way, the hot-wire air flow sensor 12 can predict the pulsation error to some extent from the magnitude of the pulsation and the pulsation frequency. Here, a pulsation amplitude ratio is used as an index indicating the magnitude of pulsation. The pulsation amplitude ratio is obtained by dividing the pulsation amplitude amount, which is the difference between the maximum flow rate and the minimum flow rate at the time of pulsation, by the average air amount at that time, as shown in the following formula (1). It is an index indicating how much the amplitude is with respect to.
Pulsation amplitude ratio = (Pulsation maximum flow rate-Pulsation minimum flow rate) / Average air volume x 100 [%] (1)

  FIG. 11 shows the tendency of the pulsation error at different frequencies. In the case of an airflow sensor capable of detecting a backflow, the pulsation error curve has an S-shaped characteristic as shown in FIG. 11, and as described above, the higher the frequency, the more the negative error. However, since the pulsation error itself can be almost predicted if the pulsation amplitude ratio and the pulsation frequency are known, correction is made to the result of converting the output value of the hot-wire airflow sensor 12 into the air amount by the air amount conversion table 105. The influence of pulsation error can be removed.

  A method for correcting the intake air amount by calculating the pulsation error will be described with reference to FIG. FIG. 12 shows an outline of internal processing when the ECU 100 executes the air amount calculation method using the output signal of the hot-wire airflow sensor 12 according to an embodiment of the present invention. In FIG. 12, the output of the hot-wire airflow sensor 12 is calculated as an intake air amount via an A / D converter 104, a sampling means 108, and an air amount conversion table 105, and the intake air amount calculation means 50 is constituted by these. The

  The internal processing executed by the ECU 100 represents a control function or an arithmetic function as a block in the drawing, and this internal processing block receives an output Va from the A / D converter 104 as an input and is a first predetermined period. The A / D conversion value is referred to by using the sampling means 108 at a certain sampling timing (for example, 2 ms). Since this A / D conversion value is a value attenuated by the frequency characteristic as described with reference to FIG. 7, it is necessary to restore the value before attenuation using the frequency response delay correcting means 109. Therefore, the current pulsation frequency is calculated from the engine speed 115 using the pulsation frequency calculation means 110, the waveform attenuation amount is predicted from the pulsation frequency, and the waveform is restored to the value before attenuation by the frequency response delay correction means 109. To do.

  Thereafter, the air amount is converted into an air amount using the air amount conversion table 205. Although the air amount conversion table 205 and the air amount conversion table 105 are the same, the air amount conversion table 105 directly converts the voltage value A / D converted by the sampling means 108 into an air amount. Since there is a difference that the voltage value after the response delay is corrected by the frequency response delay correcting means 109 is converted into an air amount, the description is distinguished. The air amount converted by the air amount conversion table 205 is stored and stored in the second period (for example, 20 ms longer than the first period) by the sampling storage unit 106, and the pulsation amplitude ratio calculation unit 112 stores the air amount. The pulsation amplitude ratio is calculated from the maximum air amount, the minimum air amount, and the average air amount in the second period.

  Since the pulsation error can be estimated from the pulsation frequency obtained from the pulsation frequency calculation unit 110 and the pulsation amplitude ratio obtained from the pulsation amplitude ratio calculation unit 112, the pulsation error calculation unit 113 calculates the pulsation error so that the pulsation error is reduced. To correct. The pulsation error calculation means 113 has a pulsation error correction map for calculating the pulsation error and correcting it by the air amount correction means 114.

  FIG. 13 shows a pulsation error correction map. The pulsation correction map has the pulsation amplitude ratio and the pulsation frequency as axes, and FIG. 13 shows an example in which the pulsation amplitude ratio is described in 100% increments and the pulsation frequency is described in increments of 20 Hz. Of course, this interval is arbitrarily set. For example, the pulsation amplitude ratio may be set in increments of 50% or finer, and the pulsation frequency may be set in increments of 10 Hz or finer. The pulsation amplitude ratio and pulsation frequency that are actually detected are often between these values, and in this case, they are obtained by interpolation calculation. A correction coefficient necessary for correcting the pulsation error from the pulsation amplitude ratio and the pulsation frequency is referred to from the pulsation error correction map.

  For example, when the pulsation amplitude ratio is 300%, the pulsation error correction map shown in FIG. 13 is “1” at a pulsation frequency of 20 Hz, “1.02” at 40 Hz, “1.05” at 60 Hz, and “1.07 at 80 Hz. ”, Gradually increases to“ 1.09 ”at 100 Hz and“ 1.12 ”at 120 Hz. When the pulsation frequency is 60 Hz, the pulsation amplitude ratio is 0%, “1”, 100% “0.99”, 200% “0.98”, 300% “1.05”, 400% “ 1.1 ”, 500%“ 1.07 ”, 600%“ 1.05 ”, 700%“ 1.02 ”, 800%“ 0.97 ”, 900%“ 0.95 ” , The peak is set at 400%. Although not shown in the figure, the blanks have the same tendency as described above, that is, with reference to the correction coefficient with a pulsation frequency of 60 Hz, the correction coefficient is set to increase as the pulsation frequency increases to 20 to 120 Hz. Has been.

  The pulsation correction coefficient for each pulsation amplitude ratio may be set so that the pulsation error is reduced due to the pulsation characteristics of the hot-wire airflow sensor 12. In the definition of the pulsation amplitude ratio, when the pulsation amplitude ratio is 200% or more, backflow will occur. However, since the hot-wire air flow sensor 12 has a small pulsation error during low pulsation as described above, no backflow occurs. The error is small when the pulsation amplitude ratio is 200% or less. Therefore, also in the pulsation correction map, the correction coefficient is set small when the pulsation amplitude ratio is 200% or less. In this pulsation error correction map, even when the pulsation amplitude ratio is 800% and 900%, the correction coefficient is set small, but in this region, the correction coefficient is set based on experiments.

  After referring to the pulsation correction coefficient from the pulsation error correction map of the pulsation error calculation unit 113, the air amount correction unit 114 calculates the air amount with the pulsation error corrected. The air amount correction unit 114 pulsates by multiplying the air amount obtained by directly converting the voltage value A / D converted by the sampling unit 108 with the air amount conversion table 105 by the pulsation correction coefficient referred to by the pulsation error calculation unit 113. The amount of air with corrected error can be calculated.

  As can be understood from the above description, according to the present embodiment, since the pulsation error can be estimated from the pulsation amplitude ratio and the pulsation frequency, the pulsation amplitude ratio considering the waveform attenuation due to the frequency characteristics of the airflow sensor, and By calculating the pulsation error correction amount from the pulsation frequency calculated from the engine speed, an amount of air with a small influence of the pulsation error is obtained. Moreover, the pulsation error of the air flow sensor 12 is corrected by using the pulsation correction map consisting of the pulsation amplitude ratio calculation means and the pulsation frequency calculation means as the output signal of the hot-wire air flow sensor 12, It is possible to obtain a highly accurate intake air amount not only in a narrow rotation region of the internal combustion engine but also in a wide rotation region.

  In addition, this invention is not limited to an above-described Example, Various modifications are included. For example, the above-described embodiments have been described in detail for easy understanding of the present invention, and are not necessarily limited to those having all the configurations described.

  In addition, it is possible to add, delete, and replace other configurations for a part of the configuration of the embodiment. For example, although the hot wire type air flow sensor has been described in the present embodiment, it goes without saying that the present invention can also be applied to an air flow sensor using a silicon element.

  Further, the control lines and information lines indicate what is considered necessary for the explanation, and not all the control lines and information lines on the product are necessarily shown. Actually, it may be considered that almost all the components are connected to each other.

DESCRIPTION OF SYMBOLS 10 ... Internal combustion engine 11 ... Air cleaner 12 ... (Heat-wire type) Air flow sensor 13 ... Throttle valve 14 ... Throttle sensor 15 ... Intake passage 16 ... Collector 17 ... Intake manifold 18 ... intake port 19 ... spark plug 20 ... ignition coil 21 ... injector 25 ... crank angle sensor 26 ... combustion chamber 27 ... piston 28 ... connecting rod 29 ... Cylinder 29a, cylinder head 29b, cylinder block 50, intake air amount calculation means 100, ECU (engine control unit)
102 ・ ・ LSI
103 ... CPU
104 ·· A / D converter 105 ·· Air amount conversion table 106 ·· Sampling means (second period)
107 .. Fuel injection pulse width calculation 108 .. Sampling means (first period)
109 ·· Frequency response delay correction means 110 ·· Pulsation frequency calculation means 112 ·· Pulsation amplitude ratio calculation means 113 ·· Pulsation error calculation means 114 ·· Air amount correction means

Claims (3)

A control device for an internal combustion engine comprising intake air amount calculation means for calculating an intake air amount based on an output value of an air flow sensor,
A pulsation amplitude ratio calculating means for calculating a pulsation amplitude ratio from the pulsation amplitude amount and average amount of intake air amount, the pulse frequency calculating means for calculating a pulsation frequency due to the rotational speed of the engine, before Symbol pulsation amplitude ratio calculating means And a pulsation error calculating means for calculating a pulsation error correction amount using a pulsation error correction map including a pulsation amplitude ratio range in which no backflow occurs and a pulsation amplitude ratio range in which a backflow occurs And an air amount correction unit that corrects the intake air amount based on the pulsation error correction amount calculated by the pulsation error calculation unit ,
The control apparatus for an internal combustion engine, wherein the air amount correction means corrects the intake air amount regardless of whether or not backflow occurs . The pulsation error correction map, according to claim 1 pulsation error auxiliary Seiryo within the scope of the pulsation amplitude ratio backflow does not occur, it characterized that you have been set smaller than the pulsation error correction amount at the time of reverse flow occurs Control device for internal combustion engine. The pulse amplitude of the intake air amount control apparatus for an internal combustion engine according to claim 1, characterized in Rukoto prompted by correcting the amount of attenuated by the frequency characteristic of the output has the air flow sensor.

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