JP4544215B2 - Control device for internal combustion engine - Google Patents

Description

  The present invention relates to a throttle valve for an internal combustion engine and a control device for the internal combustion engine.

  In order to detect the amount of intake air, an internal combustion engine is usually provided with a thermal air flow meter that detects the amount of intake air based on the amount of heat of a heating element taken away by air. Then, the output characteristics of the internal combustion engine are controlled based on the intake air amount detected by the air flow meter.

  For example, in a diesel engine, a so-called smoke limit injection amount, which is an upper limit value of the injection amount for avoiding the occurrence of smoke in exhaust gas, is calculated based on the detected value of the air flow meter and the rotational speed, and the required torque is realized. It is well known to perform an upper limit guard process on the injection amount for this purpose (Patent Document 1). Here, high reliability of the air flow meter is required. That is, when an abnormality occurs in the air flow meter, the smoke limit injection amount cannot be appropriately calculated, and there is a concern that smoke may occur.

  As described above, when an abnormality occurs in the air flow meter, there is generally a problem in controlling the output characteristics of the internal combustion engine. For this reason, it is desirable to determine whether there is an abnormality in the output of the air flow meter, or to provide a member that can be substituted when the air flow meter is abnormal.

For example, as can be seen in Patent Document 2 below, in a gasoline engine, it has also been proposed to estimate the intake air amount based on the rotational speed, the phase of the camshaft, and the compression ratio. However, in order to estimate the intake air amount in this way, the parameters used for the estimation calculation must be adapted for each gasoline engine, so that the above technique has poor versatility.
JP 2001-164967 A JP 2005-315161 A

  The present invention has been made to solve the above-described problems, and an object of the present invention is to control an internal combustion engine and an internal combustion engine that can acquire information about the air flow rate without using a normal air flow meter. Is to provide a throttle valve.

  Hereinafter, means for solving the above-described problems and the operation and effects thereof will be described.

According to a third aspect of the present invention, there is provided a throttle valve as a butterfly valve provided in an intake passage of a diesel engine as an internal combustion engine , detection means for detecting a force applied to the throttle valve, and an air flow rate based on the detected force. And an air flow meter for detecting the air flow rate separately from the calculation of the air flow rate by the calculation unit, and the air detected by the air flow meter is provided in the intake passage. The apparatus further includes a determination unit that determines whether or not the air flow meter is abnormal based on a comparison between the flow rate and the air flow rate calculated by the calculation unit .

The force applied to the throttle valve has a correlation with the air flow rate in the intake passage. Therefore, in the above configuration, the air flow rate can be calculated based on the force applied to the throttle valve. In addition, since the air flow rate can be sensed using a throttle valve provided to adjust the flow passage area of the intake passage, air can be sensed as if a new member is provided in the intake passage to sense the air flow rate. There is no increase in the number of members that hinder the distribution of the product.
In particular, in the above configuration, the air flow rate is sensed using a throttle valve of a diesel engine. Since the diesel engine causes combustion when the air is excessive, the throttle valve of the diesel engine is often fully opened. On the other hand, a simple relationship is established between the air flow rate and the lift force when the angle of attack of the throttle valve with respect to the air flow rate is small, in other words, when the throttle valve is close to the fully open state. In this regard, with the above-described configuration, it is possible to sufficiently ensure an opportunity to easily obtain information about the air flow rate.
Further, in the above configuration, by using the air flow rate calculated by the calculation means, not only an abnormality in which the output of the air flow meter does not change regardless of the change in the air flow rate, but also the output of the air flow meter according to the change in the air flow rate. Although there is a change, it is possible to appropriately determine whether there is a subtle abnormality in which this is not an accurate value.

A third aspect of the invention is characterized in that, in the first or second aspect of the invention, the throttle valve has a wing shape in a cross section perpendicular to the rotation axis thereof.

  In the above configuration, since the cross section orthogonal to the rotation axis of the throttle valve has a wing shape, lift corresponding to the air flow rate in the intake passage is applied to the throttle valve. For this reason, the information about the air flow rate can be acquired based on this lift. Since the lift is proportional to the square of the air flow rate and the flow rate is proportional to the air flow rate, the air flow rate can be easily calculated based on the lift force.

According to a second aspect of the present invention, in the first aspect of the present invention, the upper limit of the injection amount for suppressing the generation of the smoke based on the detected value of the rotational speed of the internal combustion engine and the air flow rate detected by the air flow meter. An upper limit value setting means for setting a value is further provided, and the upper limit value setting means, when the determination means determines that there is an abnormality, the calculation means for calculating the air flow rate used for setting the upper limit value. The smaller one of the air flow rate calculated by the air flow meter and the air flow rate detected by the air flow meter .

  When there is an abnormality in the air flow meter, the upper limit value by the upper limit setting means is not appropriate. Here, when it is determined by the determination means that there is an abnormality in the air flow meter, it is actually considered that either the air flow meter or the calculation result of the calculation means is abnormal. In this regard, in the above configuration, any of the above abnormalities can be appropriately dealt with by limiting the air flow rate to be equal to or lower than the air flow rate calculated by the calculating means. That is, if the detected value becomes excessive due to an abnormality in the air flow meter, the air flow for setting the upper limit value is excessive in order to limit it to the air flow calculated by the calculating means. Can be avoided. In addition, when the air flow rate calculated by the calculation means is abnormal and excessive, the air flow rate used to set the upper limit value becomes the detected value of the air flow meter, so the upper limit value should be set appropriately. Can do.

(First embodiment)
Hereinafter, a first embodiment in which a throttle valve for an internal combustion engine and a control device for an internal combustion engine according to the present invention are applied to a throttle valve for a vehicle-mounted diesel engine and a control device for a diesel engine will be described with reference to the drawings.

  FIG. 1 shows the overall configuration of an in-vehicle engine system according to the present embodiment.

  As shown in the figure, an air cleaner 14 and a thermal air flow meter 15 are provided upstream of the intake passage 12 of the diesel engine 10. A throttle valve 18 as a butterfly valve driven by a motor 16 is provided in the intake passage 12 downstream of the air flow meter 15. A throttle opening sensor 19 that detects the opening of the throttle valve 18 is provided in the vicinity of the throttle valve 18. The intake passage 12 can communicate with the combustion chamber 20 of each cylinder (here, four cylinders are illustrated). High-pressure fuel stored in the common rail 22 is injected into the combustion chambers 20 through the fuel injection valve 24. Thereby, the fuel-air mixture in the combustion chamber 20 is used for combustion, and the rotational force of the diesel engine 10 is generated.

  On the other hand, exhaust gas, which is air used for combustion, is discharged to the exhaust passage 26. The exhaust passage 26 is provided with an oxidation catalyst 28 and a NOx storage reduction catalyst 30 for storing and reducing nitrogen oxides (NOx).

  A variable nozzle type turbocharger 32 is provided in the intake passage 12 and the exhaust passage 26. Further, the intake passage 12 and the exhaust passage 26 are provided with an exhaust gas recirculation passage (EGR passage 34) that allows them to communicate with each other, and the flow passage area between the intake passage 12 and the EGR passage 34 has an EGR valve. 36 is adjustable.

  The engine system further includes various sensors that detect the operating state of the diesel engine 10, such as a crank angle sensor 40 that detects the rotation angle of the crankshaft of the diesel engine 10. The engine system also includes various sensors that detect user requests, such as an accelerator sensor 42 that detects an operation amount of an accelerator pedal.

  The electronic control unit (ECU 50) is composed mainly of a microcomputer, and operates various actuators such as the fuel injection valve 24 based on detection values of various sensors that detect the operating state of the diesel engine 10 and user requests. The output of the diesel engine 10 is controlled. In particular, the ECU 50 performs fuel injection control to control the output. That is, the required injection amount of the diesel engine 10 is calculated based on the rotational speed based on the detected value of the crank angle sensor 40 and the operation amount of the accelerator pedal detected by the accelerator sensor 42, and based on this, the fuel injection valve 24 is calculated. To operate.

  Further, the ECU 50 operates the EGR valve 36 in order to control the amount of exhaust (EGR) recirculated from the exhaust passage 26 to the intake passage 12 via the EGR passage 34. However, when the desired EGR amount cannot be achieved even by operating the EGR valve 36, the throttle valve 18 is operated to the valve closing side. Thereby, the amount of air flowing into the combustion chamber 20 side from the intake passage 12 is limited, and the EGR amount can be increased.

  By the way, in the diesel engine 10, normally, the fuel is burned in an excessive air state by opening the throttle valve 18 as much as possible. However, even in such a case, there is a possibility that sufficient air may not be supplied to the combustion chamber 20 when, for example, a vehicle on which the diesel engine 10 is mounted travels on a high altitude. If sufficient air is not supplied to the combustion chamber 20, smoke may be generated in the exhaust gas. For this reason, the air amount supplied in one combustion cycle is grasped from the air flow rate detected by the air flow meter 15 and the rotation speed based on the detected value of the crank angle sensor 40, and based on this, the upper limit value of the injection amount is obtained. A so-called smoke limit injection amount is provided.

  However, when there is an abnormality in the air flow meter 15, the smoke limit injection amount calculated based on the air flow rate detected by the air flow meter 15 is not an appropriate value. Here, when the output of the air flow meter 15 taken into the ECU 50 is fixed to a value that cannot be assumed from the opening of the throttle valve 18 due to disconnection of the propagation path of the output of the air flow meter 15 or the like. Based on this, an abnormality of the air flow meter 15 can be determined. In this case, as the limp home process at the time of abnormality, by performing a process such as limiting to an injection amount that does not generate smoke under any conditions, the retreat travel is performed while avoiding the generation of smoke. Can do. However, when the air flow meter 15 cannot detect an accurate air flow rate but its output is not a fixed value, it cannot be determined whether there is an abnormality in the above-described manner. In this case, the smoke limit injection amount calculated based on the output of the air flow meter 15 is not an appropriate value, and thus smoke may be generated during exhaust.

  Therefore, in this embodiment, the force applied to the throttle valve 18 is detected by the detection device 60, and the air flow rate is calculated based on the detected force, thereby determining whether the air flow meter 15 is abnormal.

  FIG. 2A shows an enlarged view of the throttle valve 18 according to the present embodiment. As shown in the figure, a motor 16 is connected to one end of a rotary shaft 18 a of the throttle valve 18. A detection device 60 is connected to the other end of the rotary shaft 18 a of the throttle valve 18. FIG. 2B shows an AA cross section which is a cross section orthogonal to the rotation shaft 18a. As shown in the drawing, the cross section of the throttle valve 18 has a wing shape. That is, the cross section orthogonal to the rotating shaft 18a has an arcuate streamline shape and has a shape in which the thickness gradually decreases from the vicinity of one end portion toward the other end portion. For this reason, as shown in FIG. 2C, lift force F corresponding to the air flow rate in the intake passage 12 is applied to the throttle valve 18. Here, the lift F is expressed by the following equation (f1) based on the rotation angle θ of the throttle valve 18, the air flow velocity V, the area S of the throttle valve 18, and the atmospheric density ρ.

F = 1/2 × C (θ) × ρ × V × V × S (f1)
Here, as shown in FIG. 2C, the rotation angle θ is defined with the fully open position as a reference (θ = 0). The lift coefficient C (θ) is a function of the rotation angle θ (attack angle). If the above formula (f1) is used, the air flow velocity V can be calculated by the following formula (f2) by detecting the lift F applied to the throttle valve 18.

V = √ {(2 / ρ × S) × F / C (θ)} (f2)
On the other hand, the flow passage area PS of the intake passage 12 at the rotation angle θ of the throttle valve 18 is expressed by the following equation (f3).

PS = S (1-sinθ) (f3)
Therefore, the air flow rate Qth in the intake passage 12 can be calculated by the following equation (f4).

Qth = PS × V
= S (1-sinθ) × √ {(2 / ρ × S) × F / C (θ)} (f4)
Therefore, the air flow rate Qth can be calculated based on the lift of the throttle valve 18. FIG. 3 shows the configuration of the detection device 60 that detects the lift of the throttle valve 18.

  As shown in the figure, the detection device 60 includes a case 62 that houses the rotation shaft 18a of the throttle valve 18 and a piezoelectric element 64 that is fixed to the case 62 side. The piezoelectric element 64 is provided so as to be in contact with the rotation shaft 18a at a point where the rotation angle θ of the throttle valve 18 is 90 °. As a result, regardless of the rotation angle θ of the throttle valve 18, lift is applied to the piezoelectric element 64 so as to be orthogonal to the contact surface between the piezoelectric element 64 and the rotating shaft 18a. Therefore, the value of the force applied to the piezoelectric element 64 can be set to the value of the lift F itself.

  FIG. 4 shows a processing procedure for calculating the air flow rate Q. This process is repeatedly executed by the ECU 50, for example, at a predetermined cycle.

  In this series of processes, first, in step S10, the rotation angle θ detected by the throttle opening sensor 19 is acquired. In subsequent step S12, it is determined whether or not the rotation angle θ is equal to or smaller than a predetermined angle α. Here, the predetermined angle α is set to an upper limit value of an angle at which the air flow rate Qth can be appropriately calculated based on the above formula (f4). That is, when the throttle valve 18 is close to the fully closed state, the lift applied to the throttle valve 18 becomes small, and the relational expression (f1) is not satisfied. For this reason, the region in which the air flow rate Qth can be appropriately detected by the above equation (f4) is quantified by the predetermined angle α.

  In subsequent step S14, the lift F detected by the detection device 60 is acquired. In the subsequent step S16, the air flow rate Qth is calculated by the above formula (f4) based on the lift force F and the rotation angle θ.

  When a negative determination is made in step S12 or when the process of step S16 is completed, this series of processes is temporarily terminated.

  FIG. 5 shows a processing procedure for abnormality diagnosis of the air flow meter 15 based on the air flow rate Qth. This process is repeatedly executed by the ECU 50, for example, at a predetermined cycle.

  In this series of processing, first, in step S20, the rotation angle θ is acquired. In a succeeding step S22, it is determined whether or not the rotation angle θ is equal to or less than the predetermined angle α. This determination is performed to determine whether or not the angle range is such that the air flow rate Qth can be calculated. When an affirmative determination is made in step S22, the air flow rate Qth is acquired in step S24. In the subsequent step S26, the air flow rate Qmaf detected by the air flow meter 15 is acquired.

  In the subsequent step S28, it is determined whether or not the absolute value of the difference between the air flow rate Qth calculated based on the lift force F and the air flow rate Qmaf detected by the air flow meter 15 is larger than the threshold value β. This process determines whether or not the air flow meter 15 is abnormal. That is, when the air flow meter 15 is abnormal, the air flow rate Qmaf is considered to be greatly separated from the air flow rate Qth. For this reason, the presence or absence of abnormality of the air flow meter 15 is determined based on these differences. The threshold value β is set to a value that can be taken as a difference between the air flow rate Qth and the air flow rate Qmaf when the air flow meter 15 is abnormal.

  When a positive determination is made in step S28, the process proceeds to step S30, and the air flow meter abnormality flag F is set to “1”. When a negative determination is made at step S22 or step S28, or when the process at step S30 is completed, this series of processes is temporarily terminated.

  FIG. 6 shows a procedure for calculating the smoke limit injection amount according to the present embodiment. This process is repeatedly executed by the ECU 50, for example, at a predetermined cycle.

  In this series of processes, first, in step S40, the rotation speed of the crankshaft based on the detected value of the crank angle sensor 40 is acquired. In a succeeding step S42, it is determined whether or not the air flow meter abnormality flag F is “1”. This process determines whether or not the smoke limit injection amount may be calculated assuming that the air flow rate Qmaf detected by the air flow meter 15 is the correct air flow rate. When a negative determination is made in step S42, the process proceeds to step S44 in order to calculate the smoke limit injection amount with the air flow rate Qmaf as a correct value. In step S44, the air flow rate Qmaf detected by the air flow meter 15 is acquired. In the subsequent step S46, the smoke limit injection amount is calculated based on the air flow rate Qmaf and the rotational speed.

  On the other hand, when a negative determination is made in step S42, it is determined that the correct air flow rate cannot be acquired by the air flow meter 15, and the process proceeds to step S48. In step S48, the rotation angle θ of the throttle valve 18 is limited. Since this process uses the air flow rate Qth based on the lift F when calculating the smoke limit injection amount, the rotation angle of the throttle valve 18 is limited to a rotation angle region in which the air flow rate Qth can be calculated based on the lift F. Is for. Here, it is desirable to limit the angle within the predetermined angle α. In subsequent step S50, the air flow rate Qmaf detected by the air flow meter 15 and the air flow rate Qth calculated based on the lift force are acquired. In the following step S52, the smoke limit injection amount is calculated based on the smaller one of the air flow rate Qth and the air flow rate Qmaf and the rotational speed.

  The reason why the smaller one of the air flow rate Qth and the air flow rate Qmaf is used is as follows. When it is determined that there is an abnormality in the air flow meter 15 by the process shown in FIG. 5, the air flow rate Qmaf detected by the air flow meter 15 cannot be directly used in calculating the smoke limit injection amount. Here, it is also conceivable to directly use the air flow rate Qth based on the lift F. However, the factor that causes the air flow meter abnormality flag F to be “1” by the process shown in FIG. 5 is not limited to the abnormality of the air flow meter 15, and there may be an abnormality in the air flow rate Qth based on the lift force F. For this reason, it is not appropriate to directly use the air flow rate Qth based on the lift F. On the other hand, by using the smaller one of the air flow rate Qth and the air flow rate Qmaf, it is possible to suitably avoid that the air flow rate used for calculating the smoke limit injection amount becomes excessively larger than the actual air flow rate. .

  When the processes in steps S46 and S52 are completed, this series of processes is temporarily terminated.

  According to the embodiment described in detail above, the following effects can be obtained.

  (1) The cross section perpendicular to the rotation axis of the throttle valve 18 which is a butterfly valve is shaped like a wing. Thereby, since the lift F according to the air flow rate in the intake passage 12 is applied to the throttle valve 18, the air flow rate can be sensed based on this. In addition, unlike the case where a new member is provided in the intake passage 12 to sense the air flow rate, the number of members that obstruct the air flow is not increased.

  (2) The air flow rate was calculated based on the force detected by the detection device 60 that detects the force applied to the throttle valve 18. Thereby, information about the air flow rate can be acquired.

  (3) The throttle valve 18 is applied to the diesel engine 10. Since the diesel engine 10 causes combustion when the air is excessive, the throttle valve 18 of the diesel engine 10 is often fully opened. On the other hand, the relationship of the above formula (f1) is established between the air flow rate and the lift force when the angle of attack of the throttle valve 18 with respect to the air flow direction is small, in other words, the throttle valve 18 is almost fully open. Is the time. In this respect, according to the present embodiment, it is possible to sufficiently ensure an opportunity to easily obtain information about the air flow rate.

  (4) Based on the comparison between the air flow rate Qmaf detected by the air flow meter 15 and the air flow rate Qth based on the lift F, the presence or absence of abnormality of the air flow meter 15 was determined. Thereby, not only when the output of the air flow meter 15 is fixed at an abnormal value regardless of the change in the air flow rate, but the output of the air flow meter 15 changes according to the change in the air flow rate, this is not an accurate value. The presence or absence of subtle abnormalities can also be determined appropriately.

  (5) When the air flow meter abnormality flag F is “1”, the air flow rate used for calculating the smoke limit injection amount is limited to the air flow rate Qth or less based on the lift force F. Thereby, even when the air flow meter abnormality flag F is “1”, the smoke limit injection amount can be appropriately set.

(Second Embodiment)
Hereinafter, the second embodiment will be described with reference to the drawings with a focus on differences from the first embodiment.

  FIG. 7 shows a procedure of abnormality diagnosis processing of the air flow meter 15 according to the present embodiment. This process is repeatedly executed by the ECU 50, for example, at a predetermined cycle.

  In this series of processing, first, in step S60, the air flow rate Qmaf detected by the air flow meter 15 is acquired. In a succeeding step S62, it is determined whether or not the state in which the air flow rate Qmaf is equal to or less than the predetermined amount ε continues for a predetermined period. When a negative determination is made in step S64, the process proceeds to step S64. In step S64, it is determined whether or not the state in which the air flow rate Qmaf is equal to or greater than the predetermined amount γ continues for a predetermined period. The processing of these steps S62 and S64 is based on whether there is an abnormality in which the output of the air flow meter 15 is not taken into the ECU 50 due to disconnection of the propagation path of the output signal of the air flow meter 15, or the propagation path of the output signal of the air flow meter 15 is an in-vehicle battery. Whether there is an abnormality such as a short circuit.

  If an affirmative determination is made in step S62 or step S64, it is determined in step S66 that the output of the air flow meter 15 is stuck abnormally. In step S68, limp home processing is performed. Here, the air flow rate as a calculation parameter for calculating various operation amounts for output control of the diesel engine 10 is set to the air flow rate Qth based on the lift F, or the rotation angle θ of the throttle valve 18 is limited. Process. The limitation on the rotation angle θ is for limiting the rotation angle within a region where the calculation of the air flow rate Qth based on the lift force F can be appropriately performed. This limit is desirably set to the predetermined angle α or less.

  Here, when it can be considered that the air flow rate Qth by the lift force F is less accurate than the air flow rate Qmaf by the air flow meter 15, the operation amount is calculated based on a value obtained by subtracting the predetermined amount Δ from the air flow rate Qth. It is desirable to have a margin. That is, for example, the calculation of the smoke limit injection amount is performed using a map for determining the smoke limit injection amount from the air flow rate Qmaf and the rotation speed under the assumption that the air flow meter 15 is normal. The detection accuracy is assumed. For this reason, when the accuracy of the air flow rate Qth is inferior, using this directly may not provide an appropriate value as the smoke limit injection amount. Therefore, by subtracting a predetermined amount from the air flow rate Qth, it is possible to compensate for the poor accuracy.

  When a negative determination is made in step S64 or when the process of step S68 is completed, this series of processes is temporarily terminated.

  According to the present embodiment described above, the following effects can be obtained in addition to the effects (1) to (3) of the first embodiment.

  (6) When the output of the air flow meter 15 is stuck abnormally, the air flow rate Qth based on the lift F is substituted for the air flow rate Qmaf detected by the air flow meter 15. As a result, even if the limp home operation is performed due to the abnormal fixing of the output of the air flow meter 15, it is not necessary to place an extreme limit on the output control of the diesel engine 10. For this reason, it is possible to avoid an extreme deterioration in exhaust characteristics without causing the vehicle to run at an extremely low speed.

(Other embodiments)
Each of the above embodiments may be modified as follows.

  In the process of step S52 of FIG. 6, instead of using the smaller one of the air flow rate Qth and the air flow rate Qmaf, the smaller of the value obtained by subtracting the predetermined amount Δ from the air flow rate Qth and the air flow rate Qmaf May be used. Thereby, even if the accuracy of the air flow rate Qth based on the lift F is inferior to the accuracy of the air flow rate Qmaf, it is possible to more appropriately avoid the smoke limit injection amount calculated in step S52 being excessive. it can.

  In the process shown in FIG. 6, when the air flow meter abnormality flag F is “1”, the following process may be performed instead of the process of steps S48 to S52. That is, a value obtained by subtracting the correction amount ΔTM, which increases according to the difference between the air flow rate Qth and the air flow rate Qmaf, from the air flow rate Qmaf may be used for calculating the smoke limit injection amount. As described above, the value of the air flow rate Qmaf is decreased and corrected in accordance with the degree of decrease in the reliability of the output of the air flow meter 15, thereby causing a disadvantage that the air flow rate Qmaf detected by the air flow meter 15 becomes an excessively large value. It can be avoided.

  In each of the above embodiments, the air flow rate Qth is calculated based on the lift force F and the rotation angle θ, but the present invention is not limited to this. For example, considering that there are many opportunities for the throttle valve 18 to be fully opened in the diesel engine 10, the predetermined angle α may be limited to “0”, and the air flow rate Qth may be calculated based only on the lift F. Thereby, the air flow rate Qth can be easily calculated.

  The air flow meter 15 is not limited to a thermal type, and may be a vane type or a Karman vortex type, for example.

  -The internal combustion engine is not limited to a diesel engine, and may be a gasoline engine. Even in this case, for example, it can be used for the purpose of diagnosing the presence or absence of abnormality of the air flow meter 15 during full load operation.

  The detection device 60 is not limited to that illustrated in FIG. For example, the piezoelectric element 64 may be fixed to the rotating shaft 18a side. In this case, considering that the lift force F is orthogonal to the air flow direction, the lift force F is changed to “F × cos θ” on the right side of the above formula (f4) for calculating the air flow rate Qth from the lift force F and the rotation angle θ. To do.

  The blade shape as the shape of the throttle valve 18 is not limited to that illustrated in FIG. In FIG. 2B, both the upper and lower surfaces are arched in the same direction. For example, only the upper surface may be arched.

  The throttle valve 18 is not limited to one having a wing shape in cross section perpendicular to the rotation shaft 18a. For example, even if the thickness is constant, it is possible to calculate the air flow rate based on the force applied to the throttle valve 18 in view of the correlation between the force applied to the throttle valve 18 and the air flow rate. is there. At this time, the detection device may be appropriately configured so that the force used for calculating the air flow rate can be detected.

The figure which shows the whole structure of the engine system concerning 1st Embodiment. The enlarged view of the throttle valve concerning the embodiment. The enlarged view of the throttle valve and detection device concerning the embodiment. The flowchart which shows the procedure of the calculation process of the air flow rate based on the lift concerning the embodiment. The flowchart which shows the procedure of the abnormality diagnosis process of the airflow meter concerning the embodiment. The flowchart which shows the procedure of the calculation process of the smoke limit injection quantity concerning the embodiment. The flowchart which shows the process sequence of the output sticking abnormality diagnosis of the airflow meter concerning 2nd Embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Diesel engine, 15 ... Air flow meter, 18 ... Throttle valve, 50 ... ECU (one Embodiment of the control apparatus of an internal combustion engine), 60 ... Detection apparatus.

Claims (3)

A throttle valve as a butterfly valve provided in an intake passage of a diesel engine as an internal combustion engine;
Detecting means for detecting a force applied to the throttle valve;
Calculating means for calculating an air flow rate based on the detected force,
In addition to the calculation of the air flow rate by the calculation means, an air flow meter that detects the air flow rate is provided in the intake passage,
A control device for an internal combustion engine, further comprising a determination unit that determines whether or not the air flow meter is abnormal based on a comparison between an air flow rate detected by the air flow meter and an air flow rate calculated by the calculation unit. . Further comprising an upper limit setting means for setting an upper limit value of the injection amount for suppressing the occurrence of the smoke based on the detected value of the rotational speed of the internal combustion engine and the air flow rate detected by the air flow meter;
The upper limit value setting means detects the air flow rate used for setting the upper limit value by the air flow rate calculated by the calculation means and the air flow meter when the determination means determines that the abnormality exists. It is a smaller control system for an internal combustion engine according to claim 1, wherein ones of the flow rate of the air. The control device for an internal combustion engine according to claim 1 or 2 , wherein the throttle valve has a blade shape in a cross section orthogonal to a rotation axis thereof.

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