Control device for internal combustion engine

Abstract

The problem addressed by the present invention is to obtain a control device for an internal combustion engine with which a value outputted by a flow rate sensor provided to an intake flow path of the internal combustion engine can be appropriately corrected, and error between the corrected air flow rate and the actual air flow rate can be reduced. This control device (100) for an internal combustion engine (10) is characterized by comprising a CPU (103) that computes an intake air rate for the internal combustion engine on the basis of a sensor signal of an air flow sensor (12) provided to an intake passage (15), computes a pulsation rate from a pulsation amplitude of the intake air amount of the average air amount, and calculates a correction value for correcting pulsation error in the intake air amount using the pulsation rate and the speed of the internal combustion engine, a computation device having an engine pulsation correction map (131), a blow-by pulsation correction map (132), and a criteria determination unit (133) that selects one of these two correction maps on the basis of parameters that determine the operating range of the internal combustion engine and uses the selected map to calculate the correction value.

Description

Technical Field

[0001] The present invention relates to a control device for an internal combustion engine.

Background Art

[0002] Conventionally, an invention related to a control device for an internal combustion engine equipped with an air flow sensor has been known (Patent Document 1). The control device of Patent Document 1 includes an intake air amount calculation means, a pulsation amplitude ratio calculation means, a pulsation frequency calculation means, and a pulsation error calculation means. The intake air amount calculation means calculates the intake air amount based on the output value of the air flow sensor. The pulsation amplitude ratio calculation means calculates the pulsation amplitude ratio (pulsation rate) from the pulsation amplitude amount and the average air amount of the intake air amount. The pulsation frequency calculation means calculates the pulsation frequency caused by the engine speed. The pulsation error calculation means calculates a pulsation error correction amount using the pulsation amplitude ratio and the pulsation frequency. The control device of Patent Document 1 is characterized by correcting the intake air amount based on the pulsation error correction amount.

[0003] That is, the control device of Patent Document 1 first obtains the pulsation frequency from the engine speed. Next, a frequency response correction amount for correcting the frequency response of the hot wire type air flow sensor is obtained from this pulsation frequency. Next, the pulsation amplitude ratio is obtained from this frequency response correction amount and the air flow sensor output value. Then, the air flow sensor output value is corrected so as to obtain the final air amount by means of a pulsation error correction map composed of the pulsation frequency and the pulsation amplitude ratio.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

[0005] As described above, the control device for an internal combustion engine according to Patent Document 1 corrects the air flow sensor output value based on the pulsation amplitude ratio (pulsation rate) and the pulsation frequency (rotation speed). However, in the intake pulsation, in addition to the engine pulsation due to the blowback from the combustion chamber, there is also a blow-by pulsation due to the pressure fluctuation in the crankcase. When correcting the intake air amount with the pulsation rate, it is impossible to separate the two, and there is a possibility that the optimal correction value may not be applied.

[0006] The present invention has been made in view of such problems, and an object thereof is to appropriately correct the sensor signal of an air flow sensor provided in the intake passage of an internal combustion engine and reduce the error between the corrected air flow rate and the actual air flow rate. It is to provide a control device for an internal combustion engine capable of doing so.

Means for Solving the Problems

[0007] The control device for an internal combustion engine according to the present invention is calculates the intake air amount of the internal combustion engine based on the sensor signal of an air flow sensor provided in the intake passage, calculates the pulsation rate from the pulsation amplitude amount and the average air amount of the intake air amount, and uses the pulsation rate and the engine speed of the internal combustion engine. A control device for an internal combustion engine provided with an arithmetic device that calculates a correction value for correcting a pulsation error of the intake air amount, the arithmetic device is an engine pulsation error correction unit that corrects the pulsation error of the intake air amount caused by blowback from the combustion chamber of the internal combustion engine; a blow-by pulsation error correction unit that corrects the pulsation error of the intake air amount caused by pressure fluctuation in the crankcase of the internal combustion engine; Based on a parameter for determining the operating region of the internal combustion engine, it is characterized by having a criteria determination unit that selects either the engine pulsation error correction unit or the blow-by pulsation error correction unit and uses it for calculating the correction value.

Effects of the Invention

[0008] According to the present invention, it is possible to reduce the error between the corrected air flow rate and the actual air flow rate. Further features related to the present invention will become apparent from the description in this specification and the accompanying drawings. In addition, problems, configurations, and effects other than those described above will be clarified by the description of the following embodiments.

Brief Description of the Drawings

[0009]

Figure 1

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Embodiments for Carrying Out the Invention

[0010] 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 device for an internal combustion engine according to the present invention is applied.

[0011] The internal combustion engine 10 of the present embodiment is an engine mounted on a vehicle such as an automobile. The internal combustion engine 10 is, for example, a spark ignition type four-cycle multi-cylinder engine having four cylinders, and includes a cylinder 29 composed of a cylinder head 29a and a cylinder block 29b, and a piston 27 slidably inserted into each cylinder of the cylinder 29. The piston 27 is connected to a crankshaft 42 via a connecting rod 28. The crankshaft 42 is rotatably supported in a crankcase 43 below the cylinder 29. Above the piston 27, a combustion chamber 26 having a ceiling portion of a predetermined shape is defined, and an ignition plug 19 to which an ignition signal boosted to a high voltage from an ignition coil 20 is supplied is provided facing the combustion chamber 26 of each cylinder.

[0012] The combustion chamber 26 communicates with an intake passage 15 including an air cleaner 11, an electronically controlled throttle 13, a collector 16, an intake manifold 17, an intake port 18, and the like. Air required for fuel combustion passes through the intake passage 15 and is inhaled into the combustion chamber 26 of each cylinder through an intake valve 30 that is opened and closed by an intake camshaft 22 disposed at an end of the intake port 18, which is the downstream end of the intake passage 15. An injector 21 that injects fuel toward the intake port 18 is provided for each cylinder facing the intake manifold 17 of the intake passage 15.

[0013] An air flow sensor 12 for detecting the amount of intake air is disposed downstream of the air cleaner 11 of the intake passage 15. Downstream of the air flow sensor 12, an electronically controlled throttle (hereinafter, may be simply referred to as a throttle valve) 13 that controls the throttle opening by electronic control is arranged. One end of a blow-by gas passage 61 is connected between the air flow sensor 12 and the electronically controlled throttle 13 of the intake passage 15. The blow-by gas passage 61 is for supplying blow-by gas in the crankcase 43 to the intake passage 15, and the other end is connected to a crank chamber of the crankcase 43.

[0014] The air-fuel mixture of the air inhaled through the intake passage 15 and the fuel injected from the injector 21 is inhaled into the combustion chamber 26 through the intake valve 30, and is burned by spark ignition by the spark plug 19 connected to the ignition coil 20. Then, the exhaust gas after combustion in the combustion chamber 26 is exhausted from the combustion chamber 26 through the exhaust valve 31 that is opened and closed by the exhaust camshaft 23, and is discharged into the external atmosphere through an exhaust passage 32 provided with an exhaust port, an exhaust manifold, an exhaust pipe, etc. (not shown).

[0015] Furthermore, on the downstream side of the exhaust passage 32, a three-way catalyst 35 for purifying exhaust gas, in which platinum, palladium, etc. are coated on a carrier such as alumina or ceria, is disposed. On the upstream side of this catalyst 35, a linear air-fuel ratio sensor 33 having a linear output characteristic with respect to the air-fuel ratio before the catalyst is disposed, and on the downstream side of the catalyst 35, an O2 sensor 34 that outputs a switching signal for identifying whether the air-fuel ratio after the catalyst is on the rich side or the lean side with respect to the stoichiometric (theoretical air-fuel ratio) is disposed.

[0016] Also, the injector 21 provided for each cylinder of the internal combustion engine 10 is connected to the fuel tank 36. The fuel inside the fuel tank 36 is regulated to a predetermined fuel pressure by a fuel supply mechanism including a fuel pump 37, a fuel pressure regulator 38, etc. and supplied to the injector 21. The injector 21 supplied with the fuel at the predetermined fuel pressure is valve-opened 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 (Engine Control Unit) 100, and injects a fuel amount corresponding to the valve opening time toward the intake port 18.

[0017] The ECU 100 is a control device for the internal combustion engine 10, and incorporates a microcomputer for performing various controls of the internal combustion engine 10, such as fuel injection control (air-fuel ratio control) by the injector 21 and ignition timing control by the spark plug 19.

[0018] Figure 2 shows the overall configuration of the ECU 100. The ECU 100 is composed of a power supply IC 101 and an LSI 102. The 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.

[0019] Signals from these sensors, such as the crank angle sensor 25 for detecting the engine speed, the water temperature sensor 40 for detecting the cooling water temperature of the internal combustion engine 10, the throttle sensor 14 for detecting the throttle opening of the throttle valve 13, the air-fuel ratio sensor 33 for detecting the oxygen concentration in the exhaust gas, the starter switch 41, and the air flow sensor 12, etc., are input to the ECU 100.

[0020] The detection signals from these sensors are input to the LSI (input processing circuit) 102 in the ECU 100 and are processed separately into those detected by the A / D converter as analog inputs and those detected at High / Low levels. The LSI 102 has a CPU 103 which is an arithmetic unit.

[0021] The CPU 103 executes predetermined digital arithmetic processing according to the program stored in the storage means in the ECU 100, outputs control signals for various actuators necessary for controlling the internal combustion engine 10 from this arithmetic result, and has a function of controlling various actuators via the output circuit of the LSI (input processing circuit) 102.

[0022] For example, in the CPU 103, the fuel injection amount is calculated by adding correction amounts including the mass flow rate measured from the detection signal of the air flow sensor 12, the rotational speed of the internal combustion engine 10 measured from the crank angle sensor 25, and the water temperature detected from the water temperature sensor 40, and a correction amount corresponding to the air-fuel ratio state detected by the air-fuel ratio sensor 33, and finally, a process of outputting the fuel injection amount as a drive pulse width to each injector 21 of the internal combustion engine 10 is performed. Similarly, in the CPU 103, processes of outputting an ignition signal for controlling the energization timing to the ignition coil 20 required for combustion of the internal combustion engine 10, a signal to the electronic throttle 13 for controlling the throttle opening, etc. are also performed.

[0023] The air flow sensor 12 has a heating resistor arranged in the air flow to be measured as a main component. The current value flowing through the heating resistor increases when the intake air amount is large, and conversely decreases when the intake air amount is small. A bridge circuit is configured so that the intake air amount is taken out as a voltage signal by the current flowing through the heating resistor. It is a hot-wire type. Note that the voltage signal corresponding to the intake air amount is output as a voltage value, and in some cases, it is converted into a frequency signal by a voltage-frequency conversion circuit and then output.

[0024] The ECU 100 has storage means such as a ROM and a RAM. In the storage means of the ECU 100, a correction map (pulsation error correction unit) for correcting the pulsation error of the intake air amount measured by the air flow sensor 12 is stored. The pulsation error is the deviation between the true value Q of the intake air amount and the intake air amount Qa detected by the air flow sensor 12, and can be obtained by the formula (Qa - Q) / Q.

[0025] An example of a method for correcting the pulsation error of the intake air amount will be described with reference to FIGS. 3 to 5. FIGS. 3 to 5 show an outline of the internal processing when the ECU 100 executes an air amount calculation method using the output signal of the air flow sensor.

[0026] FIG. 3 is a functional block diagram of the correction means for the intake air amount. As an internal function embodied by executing a software program, as shown in FIG. 3, the ECU 100 has an air quantity calculation means 111, a correction value calculation means 112, and a correction execution means 113.

[0027] The air quantity calculation means 111 calculates the intake air quantity of the intake air sucked into the internal combustion engine 10 based on the sensor signal of the air flow sensor 12. The correction value calculation means 112 calculates a correction value for correcting the error included in the intake air quantity calculated based on the sensor signal 61 of the air flow sensor 12. The correction value calculation means 112 calculates a correction value for correcting the error by referring to a correction map stored in advance in the memory of the ECU 100. The correction execution means 113 corrects the intake air quantity calculated by the air quantity calculation means 111 using the correction value calculated by the correction value calculation means 112. In the ECU 100, the fuel injection quantity is calculated using the intake air quantity after being corrected by the correction execution means 113.

[0028] FIG. 4 is a functional block diagram of the correction value calculation means. The correction value calculation means 112 has an amplitude calculation means 121, an average air quantity calculation means 122, a pulsation rate calculation means 123, and a correction map switching means 124.

[0029] The amplitude calculation means 121 calculates the amplitude amount (pulsation amplitude amount) of the intake air quantity based on the sensor signal 61a of the air flow sensor 12. The average air quantity calculation means 122 calculates the average air quantity of the intake air quantity based on the sensor signal 61a of the air flow sensor 12. The pulsation rate calculation means 123 calculates a pulsation rate 123a using the amplitude amount and the average air quantity of the intake air quantity.

[0030] The correction map switching means 124 selects one of the two correction maps stored in the memory of the ECU 100 and calculates a correction value by referring to the selected correction map. The correction map switching means 124 calculates a correction value 124a by referring to the correction map using the engine speed 62 and the pulsation rate 123a.

[0031] FIG. 5 is a functional block diagram of the correction map switching means. The correction map switching means 124 includes an engine pulsation correction map (engine pulsation error correction unit) 131, a blow-by pulsation correction map (blow-by pulsation error correction unit) 132, a criteria determination unit 133, and an output unit 134. The engine pulsation correction map 131 and the blow-by pulsation correction map 132 are pre-stored in the memory of the ECU 100. There are two types of pulsations that cause pulsation errors in the air flow sensor 12. The first is the engine pulsation in which the blowback from the combustion chamber reaches the air flow sensor 12, and the second is the blow-by pulsation in which the pressure fluctuation in the crankcase reaches the air flow sensor 12 through the blow-by gas passage 61. The correction map switching means 124 has an engine pulsation correction map 131 and a blow-by pulsation correction map 132 as two correction maps for correcting the pulsation errors generated by these two types of pulsations respectively.

[0032] The engine pulsation correction map 131 is a map that is referred to for calculating a correction value for correcting a pulsation error (engine pulsation error) of the intake air amount caused by the blowback from the combustion chamber 26 of the internal combustion engine 10. The engine pulsation error is generated when the intake air blows back from the combustion chamber 26 of the internal combustion engine 10 into the intake passage 15. The engine pulsation error is relatively small when the throttle opening of the throttle valve 13 is small or when the engine load of the internal combustion engine 10 is low, and becomes relatively large when the throttle opening is large or when the engine load of the internal combustion engine 10 is high.

[0033] The blow-by pulsation correction map 132 is a map referred to for calculating a correction value for correcting a pulsation error (blow-by pulsation error) of the intake air amount caused by the pressure fluctuation in the crank chamber of the internal combustion engine 10. The blow-by pulsation error is generated when the blow-by gas in the crank chamber of the internal combustion engine 10 passes through the blow-by gas passage 61 and is supplied to the intake passage 15. The blow-by pulsation error becomes relatively large when the throttle opening of the throttle valve 13 is small or when the engine load of the internal combustion engine 10 is low, and becomes relatively small when the throttle opening is large or when the engine load of the internal combustion engine 10 is high.

[0034] The engine pulsation correction map 131 and the blow-by pulsation correction map 132 can calculate a correction value 124a of the intake air amount by referring to the engine speed 62 which is the rotational speed of the crankshaft and the pulsation rate 123a.

[0035] The criteria determination unit 133 determines which correction map of the engine pulsation correction map 131 and the blow-by pulsation correction map 132 to use for calculating the correction value of the intake air amount. The criteria determination unit 133 makes a determination based on a parameter for determining the operating region of the internal combustion engine 10. The criteria determination unit 133 uses, as a parameter for determining the operating region of the internal combustion engine 10, any one of the throttle opening of the throttle valve 13 provided in the intake passage 15, the idle determination result, the filling efficiency, and the vehicle speed.

[0036] The output unit 134 calculates the correction value 124a by referring to either one of the engine pulsation correction map 131 and the blow-by pulsation correction map 132 selected by the criteria determination unit 133, and outputs it to the correction execution means 113.

[0037] FIG. 6 is a flowchart for explaining the correction value calculation method. The correction value calculation means 112 stores and saves the intake air volume for a predetermined period, and calculates the amplitude amount and average air volume of the intake air volume from the maximum air volume and minimum air volume for the predetermined period (S101, S102). Next, the pulsation rate is calculated using the amplitude amount and the average air volume (S103). The pulsation rate 123a is used as an index indicating the magnitude of the pulsation, and is calculated by dividing the amplitude amount of the intake air by the average air volume (pulsation rate = amplitude amount / average air volume). Then, using the pulsation rate and the engine speed, either the engine pulsation correction map 131 or the blow-by pulsation correction map 132 is selected (S104).

[0038] Figure 7 is a flowchart for explaining an example of the correction map switching method. The correction map switching means 124 acquires the throttle opening data from the electronic throttle 13 (S201), and determines whether the throttle opening is greater than a preset threshold value (S202). Here, when the throttle opening is greater than the threshold value (YES in S202), the reference to the engine pulsation correction map 131 is selected. On the other hand, when the throttle opening is less than or equal to the threshold value (NO in S202), the reference to the blow-by pulsation correction map 132 is selected. Then, the correction value of the intake air volume is calculated using the selected correction map (S205).

[0039] Figure 8 is a chart showing the relationship between the pulsation rate and the throttle opening, and is a diagram for explaining the characteristics of the engine pulsation and the blow-by pulsation. In the internal combustion engine 10, a throttle valve 13 is installed between the air flow sensor 12 and the combustion chamber 26, and the intake air volume inhaled into the combustion chamber 26 is adjusted by controlling the throttle opening of the throttle valve 13. When the throttle valve 13 is open, the opening area in the intake passage 15 becomes large, so that the engine pulsation generated by the blowback from the combustion chamber 26 easily reaches the air flow sensor 12, and the pulsation error of the air flow sensor 12 becomes large. At this time, since the throttle valve 13 is wide open, the intake air volume flowing in the intake passage 15 is large, and the influence of the blow-by pulsation is hardly received.

[0040] Conversely, when the throttle valve 13 is on the closed side, the opening area in the intake passage 15 becomes smaller, and the pulsation generated by the blowback from the combustion chamber 26 has difficulty reaching the air flow sensor 12, so the engine pulsation becomes smaller. At this time, since the throttle valve 13 is closed, the amount of intake air flowing through the intake passage 15 is small, and the influence of the blow-by pulsation becomes relatively large. That is, it can be said that the influencing factors of pulsation differ depending on the throttle opening degree.

[0041] On the other hand, there also exists a throttle opening degree region (the hatched region in Fig. 8) 173 that is less affected by either pulsation. In this throttle opening degree region 173, although the throttle opening degree is not fully open, a certain amount of air is flowing. Since the opening area of the throttle valve 13 is small, the influence of engine pulsation on the air flow sensor 12 is small, and since a certain amount of air is flowing, the influence of blow-by pulsation on the air flow sensor 12 is also relatively small.

[0042] As shown in Fig. 8, the pulsation rate 171 caused by engine pulsation is small when the throttle opening degree of the throttle valve is small, and increases as the throttle opening degree increases. On the other hand, the pulsation rate 172 caused by blow-by pulsation is large when the throttle opening degree of the throttle valve is small, and decreases as the throttle opening degree increases.

[0043] This is because, as described above, the more the throttle opening degree is open, the less the blowback from the combustion chamber 26 is inhibited from reaching upstream (the pressure loss is small), so the influence of engine pulsation on the air flow sensor 12 becomes stronger. Conversely, when the throttle opening degree is closed, the pressure loss at the throttle valve 13 becomes large, so the influence of engine pulsation on the air flow sensor 12 becomes small, but since the absolute value of the intake air amount flowing is small, the influence of blow-by pulsation becomes relatively large.

[0044] And, at the same throttle opening, the generation regions of engine pulsations and blow-by pulsations do not coexist, and there is a throttle opening region 173 where the influences of both the pulsation rate 171 caused by engine pulsations and the pulsation rate 172 caused by blow-by pulsations are small, as between the throttle openings θ1 and θ2 in FIG. 8.

[0045] In the present embodiment, the pulsation error is divided into an error caused by engine pulsations and an error caused by blow-by pulsations, and a correction map used for correcting the pulsation error of the intake air amount is switched by selecting either a correction map for engine pulsations or a correction map for blow-by pulsations according to the throttle opening. Therefore, appropriate corrections can be applied to the error caused by engine pulsations and the error caused by blow-by pulsations, respectively. Note that the switching of the correction map is performed in the throttle opening region 173, so that the step of the correction value can be eliminated and the switching can be performed smoothly.

[0046] FIG. 9 is a chart showing the pulsation error before and after correction in the present embodiment and the comparative example. FIG. 9(1) is a chart 181 showing the pulsation error before correction, FIG. 9(2) is a chart 184 showing the pulsation error after correction corrected by the configuration of the present embodiment, and FIG. 9(3) is a chart 284 showing the pulsation error after correction corrected by the configuration of the comparative example.

[0047] For example, the chart 181 of the pulsation error before correction is shown in FIG. 9(1). The pulsation error 182 and the pulsation error 183 in FIG. 9(1) have the same pulsation rate but different pulsation origins. The pulsation error 183 occurs on the plus side in the region where the throttle opening is small, and the pulsation error 182 occurs on the minus side in the region where the throttle opening is large.

[0048] A comparative example is shown in Fig. 9(3). In Fig. 9(3), the pulsation error is corrected using only the engine pulsation correction map. Therefore, in the region where the throttle opening is large, the pulsation error 182 in Fig. 9(1) is corrected to the plus side so that the error becomes the pulsation error 285 with almost 0% error in Fig. 9(3). On the other hand, in the region where the throttle opening is small, since the pulsation rate of the pulsation error 183 in Fig. 9(1) is the same as that of the pulsation error 182, the same correction amount is applied. Therefore, the pulsation error 183 is corrected to the plus side, and as a result, it becomes the pulsation error 286 in Fig. 9(3), and the error becomes even larger than before the correction.

[0049] In contrast, in the present embodiment, as shown in Fig. 9(2), in the region where the throttle opening is small, instead of the engine pulsation correction map, the blow-by pulsation correction map is used to correct the pulsation error. Therefore, it is possible to perform correction suitable for the pulsation error caused by the blow-by pulsation. As a result, also in the region where the throttle opening is small, the pulsation error 183 can be corrected to the pulsation error 186 near almost 0%.

[0050] In the above-described present embodiment, the configuration in which the switching between the engine pulsation correction map and the blow-by pulsation correction map is performed based on the throttle opening has been described. That is, the case where the parameter for determining the operating region of the internal combustion engine 10 is the throttle opening and the correction map is switched according to the throttle opening has been described as an example. However, the parameter for determining the operating region of the internal combustion engine 10 is not limited to the throttle opening, and for example, an engine load such as an idle determination result, a filling efficiency, or a vehicle speed may be used.

[0051] The idle determination result is the result of determining whether the internal combustion engine 10 is in an idle state. For example, when it is not determined to be idle (non-idle state), since the internal combustion engine 10 is considered to be operating the engine with an appropriate engine load, it is considered to be in a state affected by engine pulsation. Therefore, the pulsation error is corrected using the correction value calculated using the engine pulsation correction map 131. On the other hand, when it is determined to be idle (idle state), since the internal combustion engine 10 is considered to be operating the engine at an extremely low load, it is considered to be in a state affected by blow-by pulsation. Therefore, the pulsation error is corrected using the correction value calculated by referring to the blow-by pulsation correction map 132.

[0052] When the filling efficiency is high, since the internal combustion engine 10 is considered to be operating at a high load, the throttle opening is on the open side, and it is considered to be in a state affected by engine pulsation. Therefore, the pulsation error is corrected using the correction value calculated by referring to the engine pulsation correction map 131. On the other hand, when the filling efficiency is low, since the internal combustion engine 10 is operating at a low load, the throttle opening is on the closed side, and it is in a state affected by blow-by pulsation. Therefore, the pulsation error is corrected using the correction value calculated by referring to the blow-by pulsation correction map 132.

[0053] When the vehicle speed is high, since the internal combustion engine 10 is considered to be operating at a high load, the throttle opening is on the open side, and it is considered to be in a state affected by engine pulsation. Therefore, the pulsation error is corrected using the correction value calculated by referring to the engine pulsation correction map 131. On the other hand, when the vehicle speed is low, since the internal combustion engine 10 is operating at a low load, the throttle opening is on the closed side, and it is in a state affected by blow-by pulsation. Therefore, the pulsation error is corrected using the correction value calculated by referring to the blow-by pulsation correction map 132. Note that when the vehicle speed is low, it refers to a state where the vehicle is completely stopped or is traveling at a low speed (creeping) due to a creep phenomenon.

[0054] According to the present embodiment, based on the throttle opening or the engine load, which are parameters for determining the operating region, one of the engine pulsation correction map and the blow-by pulsation correction map is selected to calculate a correction value for the pulsation error. Therefore, corrections corresponding to the pulsation error caused by the engine pulsation and the pulsation error caused by the blow-by pulsation can be performed, and the measurement accuracy of the intake air amount can be improved. Thus, for example, it can contribute to improving the EGR measurement accuracy, and as a result, the EGR margin can be reduced and the EGR rate can be increased.

[0055] As described above, the embodiments of the present invention have been described in detail. However, the present invention is not limited to the above-described embodiments, and various design changes can be made without departing from the spirit of the present invention described in the claims. 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. Also, a part of the configuration of one embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of one embodiment. Furthermore, for a part of the configuration of each embodiment, addition, deletion, or replacement with other configurations is possible.

Description of Reference Numerals

[0056] 10... Internal combustion engine, 12... Airflow sensor, 13... Throttle valve, 15... Intake passage, 26... Combustion chamber, 100... ECU (control device), 102... CPU, 111... Air amount calculation means, 112... Correction value calculation means, 113... Correction execution means, 121... Amplitude calculation means, 122... Average air amount calculation means, 123... Pulsation rate calculation means, 124... Correction map switching means, 131... Engine pulsation correction map (engine pulsation error correction unit), 132... Blow-by pulsation correction map (blow-by pulsation error correction unit), 133... Criteria determination unit, 134... Output unit

Claims

1. A control device for an internal combustion engine, comprising an arithmetic unit that calculates an intake air amount of the internal combustion engine based on a sensor signal of an air flow sensor provided in an intake passage, calculates a pulsation rate from a pulsation amplitude amount and an average air amount of the intake air amount, and calculates a correction value for correcting a pulsation error of the intake air amount using the pulsation rate and an engine speed of the internal combustion engine, wherein the arithmetic unit includes an engine pulsation error correction unit that corrects a pulsation error of the intake air amount caused by blowback from a combustion chamber of the internal combustion engine, a blow-by pulsation error correction unit that corrects a pulsation error of the intake air amount caused by pressure fluctuation in a crank chamber of the internal combustion engine, a criteria determination unit that selects either one of the engine pulsation error correction unit and the blow-by pulsation error correction unit based on a parameter for determining an operating region of the internal combustion engine and uses the selected unit for calculating the correction value. The control device for an internal combustion engine is characterized by this.

2. The control device for an internal combustion engine according to claim 1, wherein the criteria determination unit uses, as a parameter for determining an operating region of the internal combustion engine, any one of a throttle opening of a throttle valve provided in the intake passage, an idle determination result, a filling efficiency, and a vehicle speed.

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