JP2007009867A - Intake air volume calculator of internal combustion engine with supercharger - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To calculate an intake air volume with high precision without undergoing constraints resulting from a hardware structure. <P>SOLUTION: An air flow meter output GA is obtained (step 100). Then, an engine revolution speed NE, a throttle opening degree TA and an air bypass valve opening degree θabv are obtained (step 102). A correction coefficient Kabv is calculated depending on the engine revolution speed NE, the throttle opening degree TA and the air bypass valve opening degree θabv that have been obtained (step 104). A final air flow meter output GAc is calculated by multiplying the air flow meter output GA by the correction coefficient Kabv (step 106). <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a supercharged internal combustion engine, and more particularly to calculation of an intake air amount.

  Conventionally, an internal combustion engine provided with a supercharger is known. In such an internal combustion engine, in order to avoid a turbo surge, the upstream side and the downstream side of the compressor of the turbocharger are bypassed by an air bypass passage, and an air bypass valve is provided in the air bypass passage (for example, Patent Documents). 1).

JP-A-4-279726

However, when the air bypass valve is opened, drift occurs in the intake passage. As a result, the output of the air flow meter is deviated, and a situation may occur in which the intake air amount cannot be calculated with high accuracy.
Therefore, it is conceivable to widen the distance between the air flow meter and the air bypass passage so as not to be affected by the drift. However, restrictions on the hardware configuration are added.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to accurately calculate the intake air amount without being restricted by hardware configuration.

In order to achieve the above object, a first invention is an intake air amount calculation device for an internal combustion engine with a supercharger,
An air flow meter provided upstream of the supercharger in the intake passage;
An air bypass passage communicating the upstream side and the downstream side of the compressor of the supercharger;
An air bypass valve that opens and closes the air bypass passage;
Air bypass valve opening degree detecting means for detecting the air bypass valve opening degree;
Output correction means for correcting the output of the air flow meter based on the opening degree of the air bypass valve.

The second invention is an intake air amount calculation device for an internal combustion engine with a supercharger,
An air flow meter provided upstream of the supercharger in the intake passage;
An air bypass passage communicating the upstream side and the downstream side of the compressor of the supercharger;
An air bypass valve that opens and closes the air bypass passage;
Air bypass valve opening degree detecting means for detecting the air bypass valve opening degree;
Engine speed value acquisition means for acquiring the engine speed value;
Throttle opening obtaining means for obtaining the throttle opening;
Output correction means for correcting the output of the air flow meter based on the engine speed value, the throttle opening, and the air bypass valve opening is provided.

  According to a third aspect of the present invention, in the first or second aspect of the invention, the output correction means corrects the output of the air flow meter to a greater extent when the air bypass valve opening is large than when it is small. It is characterized by being.

  According to the first invention, the output of the air flow meter is corrected based on the air bypass valve opening. Thereby, the output deviation of the air flow meter due to the opening operation of the air bypass valve can be corrected. Moreover, in order to avoid the output deviation of the air flow meter, the arrangement position of the air flow meter is not restricted. Therefore, the intake air amount can be calculated with high accuracy without being restricted by the hardware configuration.

  According to the second invention, the output of the air flow meter is corrected based on the engine speed value, the throttle opening, and the air bypass valve opening. Thereby, the output deviation of the air flow meter due to the opening operation of the air bypass valve can be corrected. Moreover, in order to avoid the output deviation of the air flow meter, the arrangement position of the air flow meter is not restricted. Therefore, the intake air amount can be calculated with high accuracy without being restricted by the hardware configuration.

  According to the third invention, when the air bypass valve opening degree is large, the output of the air flow meter is largely corrected as compared with the case where the air bypass valve opening is small. Therefore, appropriate correction is possible according to the output deviation of the air flow meter.

  Embodiments of the present invention will be described below with reference to the drawings. In addition, the same code | symbol is attached | subjected to the element which is common in each figure, and the overlapping description is abbreviate | omitted.

[Description of system configuration]
FIG. 1 is a diagram showing a system configuration according to an embodiment of the present invention. The system according to the present embodiment is an engine having a supercharger.
The system of the present embodiment includes an engine body 2 having a plurality of cylinders 2a. The engine body 2 is provided with a cooling water temperature sensor 4. The piston of each cylinder 2a is connected to a common crankshaft 6 via a crank mechanism. A crank angle sensor 8 is provided in the vicinity of the crankshaft 6. The crank angle sensor 8 is configured to detect the rotation angle of the crankshaft 6.

  An intake manifold 10 is connected to the engine body 2. The intake manifold 10 is provided with a supercharging pressure sensor 12. The supercharging pressure sensor 12 is configured to measure a pressure of air (hereinafter referred to as “supercharging air”) that is supercharged by a compressor 36a described later, that is, a supercharging pressure PIM.

  The intake manifold 10 has an intake port 14 corresponding to each cylinder 2a. Each intake port 14 is provided with an injector 16. The injector 16 is configured to inject fuel near the intake port 14. The plurality of injectors 16 are connected to a common delivery pipe 18. The delivery pipe 18 communicates with the fuel tank 22 via the fuel pump 20.

  An intake passage 24 is connected to the intake manifold 10. A throttle valve 26 is provided midway in the intake passage 24. The throttle valve 26 is an electronically controlled valve that is driven by a throttle motor 28. The throttle valve 26 is driven based on the accelerator opening AA detected by the accelerator opening sensor 30. A throttle opening sensor 32 is provided in the vicinity of the throttle valve 26. The throttle opening sensor 32 is configured to detect the throttle opening TA.

  An intercooler 34 is provided upstream of the throttle valve 26. The intercooler 34 is configured to cool the supercharged air.

  A compressor 36 a of the supercharger 36 is provided upstream of the intercooler 34. The compressor 36a is connected to the turbine 36b via a connecting shaft 36c. The turbine 36b is provided in an exhaust passage 48 described later. The turbine 36b is rotationally driven by the exhaust energy, so that the compressor 36a is rotationally driven.

An air flow meter 38 is provided upstream of the compressor 36a. As the air flow meter 38, for example, a hot wire type air flow meter can be used. Near the center of the intake passage 24, a measuring unit 38a of the air flow meter 38 is disposed (see FIG. 2). The measurement unit 38a is provided with a heat ray. When the hot wire is cooled by the air flowing through the intake passage 24, the hot wire is heated to a predetermined temperature. The air flow meter 38 outputs an air flow meter output GA based on the amount of electricity required to heat the hot wire.
An air cleaner 40 is provided upstream of the air flow meter 38. The upstream of the air cleaner 40 is open to the atmosphere.

  One end of an air bypass passage 42 is connected between the compressor 36 a and the air flow meter 38. The other end of the air bypass passage 42 is connected between the compressor 36 a and the intercooler 34. That is, the upstream side and the downstream side of the compressor 36 a are communicated with each other by the air bypass passage 42. An air bypass valve 44 for opening and closing the air bypass passage 42 is provided in the middle of the air bypass passage 42. In the vicinity of the air bypass valve 44, an air bypass valve opening sensor 45 is provided. The air bypass valve opening sensor 45 is configured to detect the air bypass valve opening θabv.

  An exhaust manifold 46 is connected to the engine body 2 so as to face the intake manifold 10. An exhaust passage 48 is connected to the exhaust manifold 46. As described above, the exhaust passage 48 is provided with the turbine 36 b of the supercharger 36. The turbine 36 a is configured to be rotationally driven by the energy of the exhaust gas flowing through the exhaust passage 48. A catalyst 50 for purifying exhaust gas is provided downstream of the turbine 36b. An air-fuel ratio sensor 52 is provided upstream of the catalyst 50. The air-fuel ratio sensor 52 is configured to detect the exhaust air-fuel ratio.

  One end of an EGR passage 54 is connected to the exhaust manifold 46. The other end of the EGR passage 54 is connected in the vicinity of the connection portion between the intake manifold 10 and the intake passage 24. An EGR valve 56 is provided in the vicinity of the connecting portion between the intake passage 24 and the other end of the EGR passage 54. An EGR cooler 58 that cools the exhaust gas flowing through the EGR passage 54 is provided in the middle of the EGR passage 54. When the EGR valve 56 is opened, a part of the exhaust gas is returned to the intake passage 24 through the EGR passage 54 and the EGR cooler 58. Since the exhaust gas has a smaller amount of oxygen than air, the amount of NOx produced can be reduced.

The system according to the present embodiment includes an ECU (Electronic Control Unit) 60 that is a control device.
Connected to the input side of the ECU 60 are a coolant temperature sensor 4, a crank angle sensor 8, a boost pressure sensor 12, an accelerator opening sensor 30, a throttle opening sensor 32, an air flow meter 38, an air bypass valve opening sensor 45, and the like. ing.
Further, the injector 16, the fuel pump 20, the throttle motor 28, the air bypass valve 44, the EGR valve 56, and the like are connected to the output side of the ECU 60.
The ECU 60 calculates the engine speed NE based on the output of the crank angle sensor 8.

[Features of the embodiment]
In the above system, when the air bypass valve 44 is opened, a part of the air supercharged by the supercharger 36 is returned to the upstream side of the compressor 36 a through the air bypass passage 42. Thereby, the pressure of the compressor 36a can be reduced. As a result, turbo surge can be avoided.

  However, when a part of the supercharged air is returned to the upstream side of the compressor 36a, the air flow is changed upstream of the compressor 36a. That is, drift occurs. As a result, the air flow velocity distribution changes at the position of the air flow meter 38. Hereinafter, with reference to FIG.2 and FIG.3, the change of the flow velocity distribution of the air by a drift will be described.

FIG. 2 is a diagram showing the air flow velocity distribution at the position A of the air flow meter 38 when there is no drift.
As shown in FIG. 2, when there is no drift, a flow velocity distribution represented by the symbol B at the position A of the air flow meter 38, that is, a steady flow velocity distribution is obtained. According to the flow velocity distribution B, the flow velocity decreases as it approaches the wall surface from the center of the intake passage 24 due to the effect of friction with the wall surface. When such a flow velocity distribution B is obtained, the flow velocity of the air flowing through the measurement unit 38a, that is, the flow velocity indicated by the symbol C is measured. Further, the intake air amount is calculated by integrating the flow velocity C for a certain period of time.

On the other hand, FIG. 3 is a diagram showing the air flow velocity distribution at the position A of the air flow meter 38 when there is a drift. As shown in FIG. 3, when there is a drift, a flow velocity distribution represented by the symbol D is obtained at the position A of the air flow meter 38. That is, the flow velocity distribution B changes to the flow velocity distribution D due to the drift. When such a flow velocity distribution D is obtained, the flow velocity of the air flowing through the measurement unit 38a, that is, the flow velocity indicated by the symbol E is measured.
Therefore, due to the influence of the drift current, the flow velocity E that is originally measured but the flow velocity E faster than the flow velocity C is measured. Therefore, the air flow meter output GA becomes large. Thus, if the output deviation of the air flow meter occurs, the intake air amount is erroneously detected.

  By the way, in order to avoid the influence of the above-mentioned drift, a method of arranging the air flow meter 38 apart from the joining portion of the intake passage 24 and the air bypass passage 42 can be considered. That is, in FIG. 4, a method of increasing the distance d can be considered. The distance d is a distance from the center position A of the air flow meter 38 to the center position F of the junction of the intake passage 24 and the air bypass passage 42. However, this method is not preferable because of restrictions on hardware configuration. That is, since the internal combustion engine of the present embodiment has the supercharger 36, the mountability is severe by itself. If the air flow meter 38 is arranged in this way, the mounting property becomes more severe.

Therefore, in this embodiment, the output deviation of the air flow meter 38 due to the influence of drift is corrected. Here, the larger the opening degree θabv of the air bypass valve 44, the larger the amount of air returned to the upstream side of the compressor 36a, so that the drift becomes larger. Therefore, when the air bypass valve opening degree θabv is large, the airflow meter output GA is corrected to be larger than when the opening degree θabv is small. Further, the air flow meter output GA is corrected in consideration of the throttle opening degree TA and the engine speed NE that affect the drift.
Therefore, according to the present embodiment, it is possible to accurately calculate the intake air amount by correcting the air flow meter output deviation due to the influence of drift.

[Specific processing in the embodiment]
FIG. 5 is a flowchart showing a routine executed by the ECU 60 in the present embodiment.
According to the routine shown in FIG. 5, first, the output GA of the air flow meter 38 is acquired (step 100). The air flow meter output GA acquired in step 100 includes an output deviation due to the influence of drift.

  Next, the engine speed NE, the throttle opening degree TA, and the air bypass valve opening degree θabv are acquired (step 102).

  Next, a correction coefficient Kabv is calculated with reference to a map stored in advance in the ECU 60 (step 104). Here, the correction coefficient Kavv corrects the output deviation of the air flow meter 38 due to drift. In step 104, a correction coefficient Kabv is calculated according to the engine speed NE, throttle opening degree TA, and air bypass valve opening degree θabv acquired in step 102. When the air bypass valve is fully closed, the correction coefficient Kabv is set to 1. This is because no drift occurs or the influence of the drift is extremely small.

  FIG. 6 is a diagram illustrating an example of the relationship among the correction coefficient Kabv, the air bypass valve opening θabv, and the throttle opening TA in a map for calculating the correction coefficient Kabv. As shown in FIG. 6, when the air bypass valve opening degree θabv is large, the correction coefficient θabv is calculated smaller than when the opening degree θabv is small. That is, the air flow meter output GA is corrected to be larger as the air bypass valve opening degree θabv is larger. Further, when the throttle opening degree TA is large, the correction coefficient θabv is calculated smaller than when the opening degree TA is small. That is, the airflow meter output GA is corrected to be larger as the throttle opening degree TA is larger.

  FIG. 7 is a diagram showing an example of the relationship among the correction coefficient Kabv, the air bypass opening θabv, and the engine speed NE in the map for calculating the correction coefficient Kabv. As shown in FIG. 7, when the engine speed NE is low, the correction coefficient Kabv is calculated smaller than when the engine speed NE is high. That is, as the engine speed NE is lower, the air flow meter output GA is largely corrected.

  Next, the final airflow meter output GAc is calculated using the correction coefficient Kabv calculated in step 104 (step 106). In step 106, the airflow meter output GA acquired in step 100 is multiplied by the correction coefficient Kabv calculated in step 104. Thereby, the air flow meter output GA is corrected. That is, the deviation of the air flow meter output due to the drift is eliminated.

  As described above, according to the routine shown in FIG. 5, the correction coefficient Kabv is calculated based on the air bypass opening θabv, and the air flow meter output GA is corrected using the correction coefficient Kabv. Thereby, the deviation | shift of the air flow meter output resulting from the valve opening operation of the air bypass valve 44 can be correct | amended. Therefore, the intake air amount can be calculated with high accuracy.

By the way, in this embodiment, the case where the air flow meter output GA is shifted in the increasing direction due to the drift has been described. However, the influence of the model of the internal combustion engine, the pipe diameter of the air bypass passage 42, the distance d shown in FIG. Therefore, there may be a case where the air flow meter output GA is shifted in the decreasing direction. In this case, an effect similar to that of the above-described embodiment can be obtained by performing correction to increase the airflow meter output GA by setting the correction coefficient to a value of 1 or more.
In the present embodiment, as shown in FIG. 6, the correction coefficient Kabv is calculated to be smaller as the throttle opening degree TA is larger. However, the present invention is not limited to this case. The present invention can also be applied to the case where the correction coefficient Kabv is calculated to be smaller as the throttle opening degree TA is smaller due to the influence of the model of the internal combustion engine.
Furthermore, in the present embodiment, as shown in FIG. 7, the lower the engine speed NE is, the smaller the correction coefficient Kavv is calculated. However, the present invention is limited to the case where the correction coefficient Kabv is calculated in this way. I can't. The present invention can also be applied to the case where the correction coefficient Kavv is calculated to be smaller as the engine speed NE is higher due to the influence of the model of the internal combustion engine.

  In the present embodiment, the engine speed NE is calculated based on the output of the crank angle sensor 8, but it may be detected by the speed sensor.

  In the present embodiment, the ECU 60 executes the process of step 102, whereby the “air bypass valve opening degree detecting means” in the first and second inventions executes the processes of step 104 and step 106. Thus, the “output correction means” in the first to third aspects of the invention is realized.

It is a figure which shows the system configuration | structure by embodiment of this invention. It is a figure which shows the flow velocity distribution of the air in the position of an airflow meter, when there is no drift. It is a figure which shows the flow velocity distribution of the air in the position of an air flow meter in the case where there exists a drift. It is a figure for demonstrating the arrangement position of an airflow meter. 4 is a flowchart showing a routine executed by ECU 60 in the embodiment of the present invention. FIG. 6 is a diagram illustrating an example of a relationship among a correction coefficient Kabv, an air bypass valve opening θabv, and a throttle opening TA in a map for calculating a correction coefficient Kabv. FIG. 6 is a diagram showing an example of a relationship among a correction coefficient Kabv, an air bypass opening θabv, and an engine speed NE in a map for calculating the correction coefficient Kabv.

Explanation of symbols

2 Engine body 2a Cylinder 4 Cooling water temperature sensor 6 Crankshaft 8 Crank angle sensor 10 Intake manifold 12 Supercharging pressure sensor 14 Intake port 16 Injector 18 Delivery pipe 20 Fuel pump 22 Fuel tank 24 Intake passage 26 Throttle valve 28 Throttle motor 30 Accelerator open Degree sensor 32 Throttle opening sensor 34 Intercooler 36 Supercharger 36a Compressor 36b Turbine 36c Connecting shaft 38 Air flow meter 38a Measuring unit 40 Air cleaner 42 Air bypass passage 44 Air bypass valve 45 Air bypass valve opening sensor 46 Exhaust manifold 48 Exhaust passage 50 Catalyst 52 Air-fuel ratio sensor 54 EGR passage 56 EGR valve 58 EGR cooler 58
60 ECU

Claims (3)

An intake air amount calculation device for an internal combustion engine with a supercharger,
An air flow meter provided upstream of the supercharger in the intake passage;
An air bypass passage communicating the upstream side and the downstream side of the compressor of the supercharger;
An air bypass valve that opens and closes the air bypass passage;
Air bypass valve opening degree detecting means for detecting the air bypass valve opening degree;
An intake air amount calculation device for an internal combustion engine with a supercharger, comprising: output correction means for correcting the output of the air flow meter based on the opening degree of the air bypass valve. An intake air amount calculation device for an internal combustion engine with a supercharger,
An air flow meter provided upstream of the supercharger in the intake passage;
An air bypass passage communicating the upstream side and the downstream side of the compressor of the supercharger;
An air bypass valve that opens and closes the air bypass passage;
Air bypass valve opening degree detecting means for detecting the air bypass valve opening degree;
Engine speed value acquisition means for acquiring the engine speed value;
Throttle opening obtaining means for obtaining the throttle opening;
An internal combustion engine with a supercharger comprising output correction means for correcting an output of the air flow meter based on the engine rotation value, the throttle opening, and the air bypass valve opening Intake air amount calculation device. The intake air amount calculation device for an internal combustion engine with a supercharger according to claim 1 or 2,
The output correction means corrects the output of the air flow meter largely when the air bypass valve opening is large compared to when it is small, the intake air of the supercharged internal combustion engine Quantity calculation device.

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