JP2010014041A - Control device for internal combustion engine - Google Patents

Abstract

A control device for an internal combustion engine capable of appropriately suppressing drivability deterioration and combustion deterioration due to excessive EGR during transient deceleration.
An internal combustion engine control device is preferably used for controlling an internal combustion engine having an EGR device. Specifically, when there is a request to reduce the rotational speed and load of the internal combustion engine during recirculation of the exhaust gas, the control means, when the EGR rate is greater than or equal to a predetermined value, the EGR rate is less than the predetermined value. Until it becomes, control to increase the intake air amount from the steady state is performed. Thereby, even if there is a control delay to the decrease side of the EGR gas at the time of transient deceleration, the temporary increase in the EGR amount can be appropriately suppressed. Therefore, it becomes possible to effectively suppress the deterioration of drivability and the deterioration of combustion due to excessive EGR.
[Selection] Figure 7

Description

  The present invention relates to a technical field for controlling an internal combustion engine having an EGR device (exhaust gas recirculation device).

  This type of technique is described in Patent Documents 1 and 2, for example. Patent Document 1 proposes a technique for reducing the opening degree of an EGR valve in order to suppress an excessive state of EGR gas (hereinafter also referred to as “EGR excess”) in a transient state during vehicle deceleration. . Patent Document 2 proposes a technique for learning the NOx concentration by increasing the amount of air and decreasing the amount of EGR gas during fuel cut when the vehicle is decelerated.

JP 2004-1000046 A JP 2004-11492 A

  However, with the technique described in Patent Document 1 described above, there may be a case where a delay occurs in the control of the EGR amount due to a delay in the valve operation speed of the EGR valve and the EGR excess cannot be appropriately suppressed. there were. For this reason, there has been a case where drivability deteriorates or combustion deteriorates. Note that Patent Document 2 does not describe control for appropriately suppressing excess EGR.

  The present invention has been made to solve the above-described problems, and controls an internal combustion engine capable of appropriately suppressing deterioration in drivability and deterioration in combustion due to excessive EGR during transient deceleration. An object is to provide an apparatus.

  In one aspect of the present invention, a control device that controls an internal combustion engine having an EGR device that recirculates exhaust gas to an intake system includes the rotational speed and load of the internal combustion engine during recirculation of exhaust gas by the EGR device. When the EGR rate in the EGR device is equal to or higher than a predetermined value when there is a request to reduce the air flow, control is performed to increase the intake air amount from the steady state until the EGR rate becomes less than the predetermined value. Control means are provided.

  The above control device for an internal combustion engine is suitably used for controlling an internal combustion engine having an EGR device. Specifically, when there is a request to reduce the rotational speed and load of the internal combustion engine during recirculation of the exhaust gas, the control means determines that the EGR rate is less than the predetermined value when the EGR rate is equal to or higher than the predetermined value. Until it becomes, control to increase the intake air amount from the steady state is performed. That is, control is performed to increase the intake air amount during transient deceleration. Thereby, even if there is a control delay to the decrease side of the EGR gas at the time of transient deceleration, the temporary increase in the EGR amount can be appropriately suppressed. Therefore, it becomes possible to effectively suppress the deterioration of drivability and the deterioration of combustion due to excessive EGR.

  In one aspect of the control apparatus for an internal combustion engine, the predetermined value corresponds to an EGR rate at which a torque fluctuation is greater than or equal to a predetermined value, and is defined in association with a load of the internal combustion engine.

  In this aspect, the control means uses a predetermined value corresponding to the EGR rate at which the torque fluctuation is greater than or equal to a predetermined value, and determines that drivability may be deteriorated when the EGR rate is equal to or higher than the predetermined value. Control to increase the amount of intake air. Thereby, the deterioration of the drivability due to EGR excess can be suppressed more effectively.

  In another aspect of the control apparatus for an internal combustion engine described above, when the control means performs control to increase the intake air amount, an output corresponding to a request to reduce the rotational speed and load of the internal combustion engine is satisfied. As further described, it further comprises means for controlling the motor generator to regenerate.

  According to this aspect, even if the intake air amount is increased at the time of transient deceleration, the deceleration request from the driver can be appropriately satisfied by generating the braking force with the motor generator.

  In another aspect of the control apparatus for an internal combustion engine described above, when the control means performs control to increase the intake air amount, an output corresponding to a request to reduce the rotational speed and load of the internal combustion engine is satisfied. As further described, it further comprises means for performing control to change the gear ratio of the continuously variable transmission. This also makes it possible to appropriately satisfy the deceleration request from the driver even if the intake air amount is increased during transient deceleration.

  Preferred embodiments of the present invention will be described below with reference to the drawings.

[overall structure]
FIG. 1 is a schematic configuration diagram of a hybrid vehicle to which the control device for an internal combustion engine according to the present embodiment is applied. Note that broken line arrows in the figure indicate signal input / output.

  The hybrid vehicle 100 mainly includes an engine (internal combustion engine) 1, an axle 2, drive wheels 3, motor generators MG1 and MG2, a power split mechanism 4, an inverter 5, a battery 6, and an ECU (Electronic Control). Unit) 50.

  The axle 2 is a part of a power transmission system that transmits the power of the engine 1 and the motor generator MG2 to the wheels 3. The wheels 3 are wheels of the hybrid vehicle 100, and only the left and right front wheels are particularly shown in FIG. The engine 1 is constituted by a gasoline engine or the like, and functions as a power source that outputs the main driving force of the hybrid vehicle 100. The engine 1 is controlled variously by the ECU 50.

  The motor generator MG1 is configured to function mainly as a generator for charging the battery 6 or a generator for supplying electric power to the motor generator MG2, and generates power by the output of the engine 1. The motor generator MG1 functions as a regenerative brake at the time of braking (deceleration), for example, and generates electric power by performing a regenerative motion. In addition, motor generator MG2 is configured to function as an electric motor that mainly assists (assists) the output of engine 1. These motor generators MG1 and MG2 are configured as, for example, synchronous motor generators, and include a rotor having a plurality of permanent magnets on the outer peripheral surface and a stator wound with a three-phase coil that forms a rotating magnetic field. Power split device 4 corresponds to a planetary gear (planetary gear mechanism), and is configured to be able to distribute the output of engine 1 to motor generator MG1 and axle 2.

  Inverter 5 is a DC / AC converter that controls power input / output between battery 6 and motor generator MG1 and motor generator MG2. For example, the inverter 5 converts the DC power extracted from the battery 6 into AC power, or supplies AC power generated by the motor generator MG1 to the motor generator MG2, respectively, and AC power generated by the motor generator MG1. Is converted into DC power and supplied to the battery 6.

  The battery 6 is a storage battery configured to function as a power source for driving the motor generators MG1 and / or MG2, and configured to be able to charge the power generated by the motor generators MG1 and / or MG2. .

  The ECU 50 includes a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and the like (not shown), and performs various controls on each component in the hybrid vehicle 100. For example, the ECU 50 performs control based on the accelerator opening detected by the accelerator opening sensor 20. Although details will be described later, the ECU 50 corresponds to a control device for an internal combustion engine in the present invention, and functions as a control means and the like.

  FIG. 2 is a schematic configuration diagram of the engine 1 shown in FIG. A solid line arrow in the figure indicates an example of a gas flow, and a broken line arrow indicates input / output of a signal.

  The engine 1 mainly includes an intake passage 11, a throttle valve 12, a throttle opening sensor 13, a fuel injection valve 14a, a spark plug 14c, a cylinder 15a, a piston 15c, a connecting rod 15d, and an exhaust passage 16. And an EGR device 17. In FIG. 2, only one cylinder 15a is shown for convenience of explanation, but the engine 1 actually has a plurality of cylinders 15a.

  Intake air (air) introduced from outside passes through the intake passage 11, and the throttle valve 12 adjusts the flow rate of intake air passing through the intake passage 11. The opening degree of the throttle valve 12 is controlled by a control signal supplied from the ECU 50. The opening of the throttle valve 12 (throttle opening) is detected by a throttle opening sensor 13, and the throttle opening sensor 13 supplies the detected throttle opening to the ECU 50.

  The intake air that has passed through the intake passage 11 is supplied to the combustion chamber 15b. The fuel injected by the fuel injection valve (injector) 14a is supplied to the combustion chamber 15b. Further, the combustion chamber 15b is provided with an intake valve 14b and an exhaust valve 14d. The intake valve 14b opens / closes to control conduction / interruption between the intake passage 11 and the combustion chamber 15b. The exhaust valve 14d controls opening / closing of the exhaust passage 16 and the combustion chamber 15b by opening and closing. In the combustion chamber 15b, the air-fuel mixture of intake air and fuel supplied as described above is burned by being ignited by the spark plug 14c. In this case, the piston 15c reciprocates by combustion, the reciprocating motion is transmitted to the crankshaft (not shown) via the connecting rod 15d, and the crankshaft rotates.

  Exhaust gas generated by combustion in the combustion chamber 15 b is exhausted from the exhaust passage 16. The exhaust passage 16 is provided with an EGR device (exhaust gas recirculation device) 17 and an exhaust purification catalyst (not shown). The EGR device 17 includes an EGR passage 18 and an EGR valve 19, and is configured to be able to recirculate a part of the exhaust gas to the intake system. Specifically, the EGR passage 18 has one end connected to the exhaust passage 16 and the other end connected to the intake passage 11. Further, an EGR valve 19 capable of adjusting the amount of EGR gas to be recirculated is provided on the EGR passage 18. The opening degree of the EGR valve 19 is controlled by a control signal supplied from the ECU 50 (hereinafter referred to as “EGR valve opening degree”).

[Control method]
Next, a control method performed by the ECU 50 in the present embodiment will be described. In the present embodiment, the ECU 50 deteriorates drivability due to excessive EGR when there is a request to reduce the rotational speed and load of the engine 1 during the exhaust gas recirculation by the EGR device 17 (that is, during transient deceleration). And control for suppressing deterioration of combustion. Specifically, the ECU 50 performs control to increase the intake air amount during such transient deceleration. Specifically, when the EGR rate is greater than or equal to a predetermined value, the ECU 50 increases the intake air amount from the steady state until the EGR rate becomes less than the predetermined value. For example, the predetermined value corresponds to an EGR rate at which the torque fluctuation is greater than or equal to a predetermined value, that is, an EGR rate at which the drivability deteriorates.

  The reason for performing such control is as follows. In order to improve fuel efficiency, a system that recirculates a relatively large amount of EGR gas within a range where combustion is established (specifically, a range where drivability is ensured and misfire does not occur) Further, EGR excess may occur due to a dead volume in the EGR device 17 or a response delay of the EGR valve opening, and drivability and combustion may be deteriorated. As one of the methods for suppressing this, it is conceivable to set the target EGR amount at the time of steady state to be low, but this method may cause deterioration of fuel efficiency at the time of steady state. In addition, a method of controlling the fuel injection amount in consideration of the delay from the dynamic characteristics of the throttle valve 12 is conceivable. However, in this method, the combustion state at the time of transition includes not only the delay of the actuator but also the disturbance of temperature and flow. Therefore, it can be said that it is difficult to control the optimum point. On the other hand, if unnecessary fuel increase is performed to stabilize combustion, it can be said that deterioration of fuel consumption and emission occurs.

  Therefore, in the present embodiment, control is performed to increase the intake air amount so that occurrence of such a problem is suppressed during transient deceleration. By doing so, even if the EGR is excessive, it is possible to perform appropriate combustion due to the large amount of intake air, and it is possible to suppress deterioration of drivability and deterioration of combustion. That is, by increasing the intake air amount, the combustion limit for EGR gas can be improved, and the exhaust pressure differential pressure can be reduced and the EGR inflow amount can be reduced under the high load condition with the maximum air amount. , Drivability deterioration and combustion deterioration can be effectively suppressed.

  Further, in the present embodiment, control for increasing the intake air amount is performed in this way, and control for regenerating the motor generator MG1 is performed so that the required output of the engine 1 is appropriately satisfied. In other words, the motor generator MG1 generates a braking force so that a feeling of deceleration according to the deceleration request from the driver is appropriately realized. Specifically, the ECU 50 determines the engine operating point based on the engine speed so that the required output of the engine 1 is satisfied while the desired intake air amount is realized, and the engine operating point is realized. The engine 1 and the motor generator MG1 are controlled.

  Next, a specific procedure of control performed in the present embodiment will be briefly described. First, the ECU 50 estimates the EGR rate at the time of transient deceleration. In other words, the EGR rate when the engine required output is suddenly decreased is estimated. From the EGR rate estimated in this way, the EGR excess amount at the time of transient deceleration can be grasped. More specifically, the ECU 50 estimates the EGR rate based on the dynamic characteristics (for example, an air model) of the throttle valve 12 and the dynamic characteristics of the EGR valve 19. Thereafter, the ECU 50 determines whether or not there is a possibility that deterioration of drivability may occur based on the estimated EGR rate (hereinafter, referred to as “drivability establishment determination”). Specifically, the ECU 50 determines the drivability establishment by comparing the estimated EGR rate with a predetermined value set in advance in association with the load of the engine 1. This predetermined value corresponds to an EGR rate at which the torque fluctuation becomes greater than or equal to a predetermined value, that is, an EGR rate at which the drivability deteriorates. That is, the predetermined value is set to an EGR rate (hereinafter, referred to as “drivability limit EGR rate”) at which drivability deteriorates when the EGR rate is equal to or greater than this value.

  Thereafter, the ECU 50 determines that the drivability establishment determination may cause a deterioration in drivability, so that the intake air amount that does not cause the drivability deterioration (hereinafter referred to as “drivability establishment air amount”). Call). That is, the ECU 50 obtains the intake air amount that can compensate for the excessive EGR amount. Specifically, the ECU 50 obtains the drivable air amount using a model or the like in consideration of improvement of the combustion limit due to the increase of the intake air amount and reduction of the EGR amount as described above. Thereafter, the ECU 50 transitions the obtained drivability establishment air amount, and determines the engine operating point from the engine speed that satisfies the transition of the required output of the engine 1. That is, a target engine speed that satisfies the deceleration request and the drivability establishment air amount is obtained, and a point defined by the engine rotation speed and the drivability establishment air amount is set as the engine operating point. Then, ECU 50 controls engine 1 and motor generator MG1 so that the operation is performed at the determined engine operating point.

  Next, the control method in the present embodiment will be described more specifically with reference to FIGS.

  FIG. 3 is a diagram for explaining a method of estimating the EGR rate at the time of transient deceleration. Note that estimating the EGR rate in this way corresponds to estimating the future expected amount of EGR gas with respect to a rapid decrease in the engine required output.

  FIG. 3A shows an example of the time change of the throttle opening. Specifically, the broken line represents the target value of the throttle opening with respect to the deceleration request, and the solid line represents the estimated value of the throttle opening. As shown in FIG. 3A, it can be seen that the estimated value of the throttle opening is delayed with respect to the target value. FIG. 3B shows an example of the intake air amount estimated from the throttle opening and the like. Note that the estimated value of the throttle opening and the estimated value of the intake air amount as shown in FIGS. 3A and 3B are obtained from the dynamic characteristics of the throttle valve 12 (for example, an air model).

  FIG. 3C shows an example of the time change of the EGR valve opening. Specifically, the broken line represents the target value of the EGR valve opening with respect to the deceleration request, and the solid line represents the estimated value of the EGR valve opening. The estimated value of the EGR valve opening is obtained based on the dynamic characteristics of the EGR valve 19 and the like. As shown in FIG. 3C, it can be seen that the estimated value of the EGR valve opening is delayed with respect to the target value. FIG. 3 (d) shows an example of the EGR rate estimated based on the estimated value of the intake air amount shown in FIG. 3 (b), the estimated value of the EGR valve opening shown in FIG. 3 (c), and the like. Yes. The estimated value of the EGR rate (hereinafter also referred to as “estimated EGR rate”) is obtained based on a physical model using the estimated value of the intake air amount, the estimated value of the EGR valve opening, and the like. From such an estimated EGR rate, an estimated amount of EGR gas (specifically, an excessive amount of EGR) at the time of transient deceleration can be grasped.

  FIG. 4 is a diagram for explaining the determination of drivability establishment. FIG. 4 shows the load of the engine 1 on the horizontal axis and the EGR rate on the vertical axis. A broken line A1 indicates an example of the drivability limit EGR rate, and a solid line A2 indicates an example of the estimated EGR rate. The drivability limit EGR rate corresponds to an EGR rate at which the torque fluctuation is greater than or equal to a predetermined value (that is, an EGR rate at which drivability is deteriorated when the torque fluctuation exceeds a predetermined value), and is determined in advance in association with the load of the engine 1. For example, it is stored as a map value.

  The ECU 50 determines the drivability establishment by comparing the estimated EGR rate and the drivability limit EGR rate. Specifically, the ECU 50 determines that the drivability may be deteriorated when the estimated EGR rate is equal to or greater than the drivability limit EGR rate, and when the estimated EGR rate is less than the drivability limit EGR rate. Determines that it is unlikely that a deterioration in drivability will occur. For example, when the estimated EGR rate exceeds the drivability limit EGR rate as indicated by the broken line region R1, the ECU 50 determines that there is a high possibility that deterioration in drivability will occur. In such a case, it can be said that not only deterioration of drivability but also combustion failure (misfire) may occur.

  FIG. 5 shows an example of the time change (dashed line B1) of the drivable air amount and the time change (solid line B2) of the estimated intake air amount. When the drivability establishment air amount indicated by the broken line B1 is determined that drivability may be deteriorated in the drivability establishment determination, the improvement of the combustion limit due to the increase of the intake air amount or the decrease of the EGR amount is considered. Thus, the intake air amount obtained using a model or the like. Specifically, the drivability establishment air amount is the intake air amount obtained by repeatedly performing the estimation of the intake air amount, the estimation of the EGR rate, the drivability establishment determination, and the like as described above. That is, the EGR rate is estimated from the estimated intake air amount, and it is less likely that the drivability deterioration will occur by repeatedly determining whether or not the drivability deterioration may occur from the EGR rate. This is the intake air amount when it is determined. On the other hand, the intake air amount indicated by the solid line B2 is the intake air amount estimated based only on the deceleration request without increasing the intake air amount. When the intake air amount is controlled, it is considered that drivability may be deteriorated due to excessive EGR. As shown in FIG. 5, it can be seen that the drivable air amount indicated by the broken line B1 is larger than the estimated intake air amount indicated by the solid line B2.

  FIG. 6 is a diagram for explaining a method of reflecting the engine operating point based on the amount of air that has been drivable. In FIG. 6, the horizontal axis indicates the engine speed, the vertical axis indicates the intake air amount, and the dashed line indicates the equal power line. The solid line C1 shows an example of a normal engine operation line, and the alternate long and short dash line C2 is an operation line reflecting an engine operation point corresponding to the amount of air that has been drivable (hereinafter referred to as a “reflection operation line”). ) Is an example. The engine operating point on the reflection operation line is determined from the engine speed that satisfies the transition of the required output of the engine 1 by changing the drivable air amount obtained as described above. That is, it is determined from the target engine speed that satisfies the deceleration request and the drivability establishment air amount. The engine 1 is operated in accordance with the reflection operation line as shown by the white arrow in FIG. 6 by executing control to regenerate the motor generator MG1 so that the engine operating point determined in this way is realized. It will be. From FIG. 6, when the engine 1 is operated according to the reflected operation line, the operating point where the intake air amount is large is shifted and decelerated compared to the case where the engine 1 is operated according to the normal engine operation line. I understand that.

  According to the control method according to the present embodiment described above, it is possible to effectively suppress deterioration in drivability and deterioration in combustion due to excessive EGR by appropriately increasing the intake air amount during transient deceleration. That is, even if there is a control delay toward the decrease side of EGR gas at the time of transient deceleration, the temporary increase in the EGR amount can be appropriately suppressed. In addition, the engine operation line can be appropriately changed to a high load condition with a low EGR rate while appropriately satisfying the driver's required output. That is, even if the intake air amount is increased during transient deceleration, the deceleration request from the driver can be appropriately satisfied by generating the braking force with the motor generator MG1.

[Control processing]
Next, a control process according to the present embodiment will be described with reference to FIG. FIG. 7 is a flowchart showing a control process according to the present embodiment. This process is executed by the ECU 50 during transient deceleration (when there is a request to rapidly reduce the engine speed and load during exhaust gas recirculation by the EGR device 17).

  First, the ECU 50 estimates the intake air amount based on the required output of the engine 1 (step S101). Specifically, the ECU 50 estimates the intake air amount based on the dynamic characteristics (such as an air model) of the throttle valve 12. For example, the ECU 50 obtains the intake air amount from a map or an arithmetic expression. In parallel with the processing in step S101, the ECU 50 estimates the EGR valve opening based on the required output of the engine 1 (step S102). Specifically, the ECU 50 estimates the EGR valve opening based on the dynamic characteristics of the EGR valve 19 and the like. For example, the ECU 50 obtains the EGR valve opening degree from a map or an arithmetic expression. When the processes in steps S101 and S102 are completed, the process proceeds to step S103.

  In step S103, the ECU 50 estimates the EGR rate based on the intake air amount estimated in step S101 and the EGR valve opening estimated in step S102. That is, the estimated EGR rate is obtained. Specifically, the ECU 50 obtains an estimated EGR rate from an estimated value of the intake air amount, an estimated value of the EGR valve opening, and the like using a physical model or the like. Then, the process proceeds to step S104.

  In step S104, the ECU 50 determines whether or not there is a possibility that deterioration of drivability will occur based on the estimated EGR rate obtained in step S103 (drivability establishment determination). Specifically, the ECU 50 performs the drivability establishment determination by comparing the estimated EGR rate and the drivability limit EGR rate. When the estimated EGR rate is equal to or greater than the drivability limit EGR rate, the ECU 50 determines that drivability may be deteriorated (step S104; Yes), and the process proceeds to step S105. On the other hand, when the estimated EGR rate is less than the drivability limit EGR rate, the ECU 50 determines that the possibility of deterioration in drivability is low (step S104; No), and the process returns to steps S101 and S102. .

  In step S105, the ECU 50 calculates the drivability establishment air amount. Specifically, the ECU 50 calculates the drivability establishment air amount by repeatedly performing the above-described estimation of the intake air amount, estimation of the EGR rate, drivability establishment determination, and the like. In other words, the EGR rate is estimated from the estimated intake air amount, and the determination is made as to whether or not there is a possibility that deterioration in drivability may occur from the EGR rate. Get the air volume. Then, the process proceeds to step S106.

  In step S106, the ECU 50 changes the drivable air amount calculated in step S105 and calculates an engine speed that satisfies the required output transition of the engine 1. That is, the target engine speed is calculated such that the driver's deceleration request and the drivability establishment air amount are satisfied. Then, the process proceeds to step S107.

  In step S107, the ECU 50 performs control to reflect the engine operating point corresponding to the target engine speed calculated in step S106. Specifically, the ECU 50 controls the engine 1, the motor generator MG1, and the like so that the engine operating point corresponding to the above-described drivability establishment air amount and the target engine speed is appropriately realized. Specifically, the ECU 50 controls the opening degree of the throttle valve 12 based on the amount of air that establishes the drivability, and controls the rotational speed of the motor generator MG1 based on the target engine rotational speed. In this case, ECU 50 performs control to regenerate motor generator MG1 so that a sense of deceleration according to the deceleration request from the driver is realized. When the above process ends, the process exits the flow.

  According to the control processing according to the present embodiment described above, drivability deterioration and combustion deterioration due to excessive EGR can be effectively suppressed while appropriately satisfying the driver's required output during transient deceleration. .

[Modification]
In the above, the embodiment has been described in which the control for regenerating the motor generator MG2 is performed so that the required output of the engine 1 is satisfied (see step S107 and the like), but the present invention is not limited to this. In another example, instead of controlling the motor generator MG2 in this way, control for changing the gear ratio of the continuously variable transmission (CVT) can be performed. That is, it is possible to perform control to change the gear ratio of the continuously variable transmission so that the engine operating point corresponding to the target engine speed that satisfies the deceleration request of the driver and the amount of air that satisfies the drivability is reflected. This also effectively suppresses deterioration of drivability due to excessive EGR while appropriately satisfying the driver's required output during transient deceleration. In addition, when performing such control, it is not necessary to apply this invention to a hybrid vehicle.

  Further, in the above, from the viewpoint of mainly suppressing deterioration of drivability due to excessive EGR, an embodiment has been described in which control is performed to increase the intake air amount so that deterioration of drivability does not occur. Not done. In another example, it is possible to perform control to increase the intake air amount so that combustion deterioration (misfire) does not occur. That is, from the viewpoint of mainly suppressing deterioration of combustion due to excessive EGR, it is possible to perform control to increase the intake air amount at which combustion is established. Also in this case, when the EGR rate is equal to or higher than the predetermined value, the intake air amount is increased from the steady state until the EGR rate becomes less than the predetermined value. In this embodiment, the predetermined value is an EGR rate at which the torque fluctuation becomes equal to or higher than the predetermined value (that is, an EGR rate at which the drivability deteriorates). However, in the modified example, combustion fails. Is set to such an EGR rate (that is, an EGR rate at which misfire occurs). Note that the predetermined value used in the modification is larger than the predetermined value used in the above-described embodiment.

The schematic block diagram of the hybrid vehicle which concerns on this embodiment is shown. The schematic block diagram of an engine is shown. It is a figure for demonstrating the method to estimate the EGR rate at the time of transient deceleration. It is a figure for demonstrating drivability establishment determination. An example of the time change of drabble formation air amount and the estimated intake air amount is shown. It is a figure for demonstrating the method of reflecting an engine operating point. It is a flowchart which shows the control processing which concerns on this embodiment.

Explanation of symbols

1 Engine 11 Intake passage 12 Throttle valve 14a Fuel injection valve 15a Cylinder 16 Exhaust passage 17 EGR device 19 EGR valve 50 ECU
100 Hybrid vehicle MG1, MG2 Motor generator

Claims (4)

A control device that controls an internal combustion engine having an EGR device that recirculates exhaust gas to an intake system,
When there is a request to reduce the rotational speed and load of the internal combustion engine during recirculation of exhaust gas by the EGR device, when the EGR rate in the EGR device is equal to or higher than a predetermined value,
A control device for an internal combustion engine, comprising control means for performing control to increase an intake air amount from a steady state until the EGR rate becomes less than the predetermined value.   2. The control device for an internal combustion engine according to claim 1, wherein the predetermined value corresponds to an EGR rate at which a torque fluctuation becomes a predetermined value or more and is defined in association with a load of the internal combustion engine.   Means for performing regenerative control of the motor generator so that an output in accordance with a request to reduce the rotational speed and load of the internal combustion engine is satisfied when the control means performs control to increase the intake air amount; The control device for an internal combustion engine according to claim 1, further comprising:   When the control means performs the control to increase the intake air amount, the gear ratio of the continuously variable transmission is changed so that the output corresponding to the request to reduce the rotational speed and load of the internal combustion engine is satisfied. The control device for an internal combustion engine according to claim 1, further comprising means for performing control.

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