JP2006307784A - Control device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a control device for an internal combustion engine, accurately controlling an air fuel ratio to a target value at the time of returning from fuel cut in deceleration, regardless of a state of exhaust gas recirculation quantity at the time of such returning, in the internal combustion engine for performing quantity increase control of the exhaust gas recirculation quantity during fuel cut in deceleration. <P>SOLUTION: During execution of fuel cut in deceleration, quantity increase control of EGR gas is performed by changing a valve overlap period. When valve overlap quantity at the time of returning from the fuel cut is below a predetermined determination value X, intake asynchronous injection is selected (injection end time 60° BTDC). In contrast, when the valve overlap quantity at the time of the returning exceeds the predetermined determination value X, intake synchronous injection is selected (injection end time 30° ATDC). <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an internal combustion engine control apparatus, and more particularly to an internal combustion engine control apparatus suitable as an apparatus for controlling an internal combustion engine that recirculates exhaust gas during execution of fuel cut during deceleration.

  Conventionally, for example, Patent Document 1 discloses a technique for increasing the fuel increase value at the time of return in accordance with the closing timing of the intake valve in an internal combustion engine that performs control to increase the fuel injection amount at the time of return from the deceleration fuel cut. Has been. More specifically, in this prior art, the later the intake valve closing timing, the larger the fuel increase value at the time of return from the deceleration fuel cut, so that the air-fuel ratio can be appropriately maintained at the time of return. .

Japanese Utility Model Publication No. 3-54257 JP-A-5-141293 Japanese Patent Laid-Open No. 11-257130 Japanese Patent Laid-Open No. 10-331612

  By the way, there is known an internal combustion engine that controls an increase in the exhaust gas recirculation amount when the fuel is decelerated. In an internal combustion engine in which such control is performed, the influence of the blowback amount due to back blow changes according to the attenuation amount of the exhaust gas recirculation amount when the fuel cut is restored. When the blowback amount increases, the amount of fuel attached to the wall surface to the intake port or the like of the injected fuel increases. Therefore, simply increasing the amount of fuel at the time of fuel cut return using the above-described conventional technique also increases the amount of fuel adhering to the wall surface under a large amount of blow-back, and the air-fuel ratio at the time of return is precisely determined. Can not be controlled.

  The present invention has been made to solve the above-described problems. In an internal combustion engine that controls the increase in the exhaust gas recirculation amount when the deceleration fuel cut is performed, the exhaust gas recirculation amount at the time of return from the deceleration fuel cut is reduced. It is an object of the present invention to provide a control device for an internal combustion engine that can precisely control the air-fuel ratio at the time of return to a target value regardless of the state.

In order to achieve the above-mentioned object, the first invention includes a fuel cut means for stopping the supply of fuel and an EGR control means for controlling the exhaust gas recirculation amount. A control device for an internal combustion engine for increasing a recirculation amount,
EGR attenuation amount acquisition means for acquiring the attenuation amount of the exhaust gas recirculation amount;
A fuel supply timing control means for controlling the fuel supply timing;
The fuel supply timing control means determines the fuel supply timing according to the attenuation amount of the exhaust gas recirculation amount when the fuel supply is resumed from the fuel cut.

In a second aspect based on the first aspect, the EGR control means comprises:
Variable valve timing control means for driving a variable valve mechanism that varies the valve overlap period in which the intake valve opening period and the exhaust valve opening period overlap to vary the internal exhaust gas recirculation amount, the intake passage and the exhaust It includes at least one of EGR valve control means for adjusting an opening degree of an EGR valve provided in the middle of the exhaust gas recirculation passage communicating with the passage to increase or decrease the amount of external exhaust gas recirculation.

In a third aspect based on the second aspect, the EGR control means is the variable valve timing control means.
The EGR attenuation amount acquisition means includes valve timing control amount acquisition means for acquiring an advance value of valve timing,
The fuel supply timing control means includes EGR amount determination means for determining a state of attenuation of the exhaust gas recirculation amount when the fuel supply is resumed based on an advance value of the valve timing.

The fourth invention is the second or third invention, wherein the EGR control means is the variable valve timing control means,
The fuel supply timing control means delays the fuel supply timing at the time of restarting the fuel supply toward the intake synchronization side more greatly as the attenuation amount of the exhaust gas recirculation amount at the time of restarting the fuel supply is smaller. It is characterized by.

In addition, the fifth invention is the second invention, further comprising intake air amount control means for controlling the intake air amount, wherein the intake air quantity is attenuated when the fuel is cut, and the EGR control means controls the EGR valve control. If it is a means,
The fuel supply timing control means controls the fuel supply timing at the time of resuming the fuel supply to the intake synchronization side when the attenuation amount of the exhaust gas recirculation amount at the time of resuming the fuel supply is large. To do.

  In a sixth aspect based on any one of the third to fifth aspects, the fuel supply timing control means moves to the intake synchronization side when the control of the fuel supply timing to the intake synchronization side is completed. The fuel supply timing is gradually returned to the supply timing before the control.

  According to the first aspect of the invention, the fuel supplied at the time of returning from the fuel cut can be made less susceptible to the back blow, and at the time of returning, the air-fuel ratio can be precisely controlled to a target value. For this reason, according to the present invention, leaning of the air-fuel ratio at the time of fuel cut recovery can be suppressed, and engine stall or the like can be avoided.

  According to the second aspect of the invention, by determining the fuel supply timing at the time of fuel cut return according to the state of attenuation of the internal exhaust gas recirculation amount or the external exhaust gas recirculation amount, the air-fuel ratio at the time of return is determined. Can be precisely controlled.

  According to the third aspect of the present invention, the fuel supply is performed in consideration of the control delay of the valve timing by the variable valve timing control means by determining the state of the exhaust gas recirculation amount attenuation based on the advance value of the valve timing. The amount of attenuation at the time of restart can be determined. Therefore, according to the present invention, the fuel supply timing can be set more precisely according to the return amount of the valve overlap amount.

  According to the fourth aspect of the invention, the smaller the attenuation amount of the exhaust gas recirculation amount at the time of fuel cut return, the greater the fuel supply timing and the retarded control to the intake synchronization side. Therefore, it is possible to suppress the influence of back blow received by the fuel supplied at the time of return.

  According to the fifth aspect of the present invention, when the attenuation amount of the exhaust gas recirculation amount at the time of fuel return is large and, as a result, the intake pipe negative pressure is large, the fuel is directly transferred to the combustion chamber at the time of return by intake synchronous injection. Since the fuel can be fed, it is possible to suppress the influence of back blow received by the fuel supplied at the time of return.

  According to the sixth aspect of the invention, after the fuel supply timing is controlled to the intake synchronization side, the fuel supply timing is gradually returned toward the supply timing before the control to the intake synchronization side. Can be suppressed.

Embodiment 1 FIG.
[Description of system configuration]
FIG. 1 is a diagram for explaining the configuration of the first embodiment of the present invention. As shown in FIG. 1, the system of the present embodiment includes an internal combustion engine 10. A combustion chamber 12 is formed in the cylinder of the internal combustion engine 10. An intake passage 14 and an exhaust passage 16 communicate with the combustion chamber 12.

  A throttle valve 18 is disposed in the intake passage 14. The throttle valve 18 is an electronically controlled valve that is driven by a throttle motor based on the accelerator opening. A throttle position sensor 20 for detecting the throttle opening degree TA is disposed in the vicinity of the throttle valve 18.

  The internal combustion engine 10 is a multi-cylinder engine having a plurality of cylinders, and FIG. 1 shows a cross section of one of the cylinders. Each cylinder included in the internal combustion engine 10 is provided with an intake port that communicates with the intake passage 14 and an exhaust port that communicates with the exhaust passage 16. A fuel injection valve 22 for injecting fuel into the intake port is disposed in the intake port. The intake port and the exhaust port are provided with an intake valve 24 and an exhaust valve 26 for bringing the combustion chamber 12 and the intake passage 14 or the combustion chamber 12 and the exhaust passage 16 into a conductive state or a cut-off state, respectively. .

  The intake valve 24 and the exhaust valve 26 are driven by an intake variable valve operating (VVT) mechanism 28 and an exhaust variable valve operating (VVT) mechanism 30, respectively. The variable valve mechanisms 28 and 30 respectively open and close the intake valve 24 and the exhaust valve 26 in synchronization with the rotation of the crankshaft, and change their valve opening characteristics (valve opening timing, operating angle, lift amount, etc.). can do.

  The internal combustion engine 10 includes a crank angle sensor 32 in the vicinity of the crankshaft. The crank angle sensor 32 is a sensor that reverses the Hi output and the Lo output each time the crankshaft rotates by a predetermined rotation angle. According to the output of the crank angle sensor 32, it is possible to detect the rotational position and rotational speed of the crankshaft, and further the engine rotational speed NE and the like. The internal combustion engine 10 also includes a cam angle sensor 34 in the vicinity of the intake camshaft. The cam angle sensor 34 is a sensor having the same configuration as the crank angle sensor 32. According to the output of the cam angle sensor 34, the rotational position (advance value) of the intake camshaft can be detected.

  An upstream catalyst (SC) 36 and a downstream catalyst (UF) 38 for purifying exhaust gas are arranged in series in the exhaust passage 16 of the internal combustion engine 10. An air-fuel ratio sensor 40 for detecting the exhaust air-fuel ratio at that position is disposed upstream of the upstream catalyst 36. Further, an oxygen sensor 42 that generates a signal corresponding to whether the air-fuel ratio at that position is rich or lean is disposed between the upstream catalyst 36 and the downstream catalyst 38.

  The system shown in FIG. 1 includes an ECU (Electronic Control Unit) 50. In addition to the various sensors described above, the ECU 50 is connected to an accelerator position sensor 52 for detecting the accelerator pedal opening PA and the various actuators described above. The ECU 50 can control the operating state of the internal combustion engine 10 based on those sensor outputs. The supply timing of the fuel injected by the fuel injection valve 22 is controlled by the ECU 50. More specifically, according to the above configuration, the fuel supply timing is normally set so that the injected fuel reaches the intake valve 24 before the exhaust top dead center arrives (intake asynchronous injection). ). Further, according to the above configuration, the fuel is injected so that the injected fuel is synchronized with the lowering of the piston during the intake stroke, in other words, the fuel reaches the intake valve 24 after the exhaust top dead center arrives. Can be set (intake-synchronized injection).

[Overview of catalyst deterioration suppression control]
The system of the present embodiment configured as described above is a process for stopping the supply of fuel when the throttle opening TA is set to the idle opening during the operation of the internal combustion engine 10, that is, a fuel cut (F / F Perform C). Since fuel injection is not performed during execution of F / C, the gas flowing into the catalyst (upstream catalyst 36 and downstream catalyst 38) is extremely lean. When a lean gas flows into the high-temperature catalyst, the catalyst tends to deteriorate.

  According to the system shown in FIG. 1, the valve opening phase of the intake valve 24 is advanced by the intake variable valve mechanism 28 (more specifically, the valve opening timing is advanced). The period during which both the intake valve 24 and the exhaust valve 26 are open can be extended. If the valve overlap period is extended during execution of F / C during deceleration when the intake pipe pressure is negative, the amount of burned gas blown back into the intake passage 14 after the intake valve 24 is opened, that is, The amount of internal EGR increases.

  Accordingly, if the throttle opening degree TA is sufficiently reduced in a state where a sufficient valve overlap is generated, a sufficient exhaust gas recirculation amount (hereinafter referred to as an EGR gas amount) can be generated. Therefore, in the system of the present embodiment, during the execution of F / C, the throttle valve 18 is controlled to the fully closed position while introducing the EGR gas into the combustion chamber 12. According to such control, it is possible to effectively suppress the progress of deterioration of the catalyst while suppressing an excessive negative pressure of the intake pipe pressure. Hereinafter, such control, that is, control for suppressing deterioration of the catalyst by introducing the EGR gas into the combustion chamber 12 while keeping the throttle valve 18 fully closed during execution of F / C during deceleration, This is referred to as “catalyst deterioration suppression control”.

[Characteristics of Embodiment 1]
When a general intake asynchronous injection mode is used in a port injection type internal combustion engine, a part of the injected fuel is blown off by back blow (blow back) and adheres to the intake port, etc. Part of the adhering fuel is taken away into the combustion chamber 12 during the intake stroke. During the execution of the deceleration F / C, since fuel injection is not executed, the fuel adhering to the wall surface is sequentially taken away. For this reason, when returning from the F / C, there is basically no fuel attached to the wall surface. Therefore, in the first cycle when returning from F / C, since the amount of fuel carried away when a part of the injected fuel adheres to the wall surface without the fuel adhering to the wall surface, the air-fuel ratio in the cycle becomes Lean.

  Then, the amount of fuel adhering to the wall surface during the first cycle when the F / C is restored changes as the amount of intake air blown back by back blow changes according to the length of the valve overlap period. More specifically, when the recovery from the F / C is performed when the catalyst deterioration suppression control is being executed, the valve overlap amount is set to the normal operation from the time when the return request from the F / C is detected. However, since the intake VVT mechanism 28 has a control delay, the return amount of the valve overlap amount when the fuel injection is resumed may not be sufficient. More specifically, in such a case, as the valve overlap amount is increased, the amount of fuel adhering to the wall surface is increased by increasing the amount of air blown back.

  Therefore, in the method of simply increasing the fuel injection amount in order to avoid leaning of the air-fuel ratio at the time of return from the deceleration F / C, an increase in the amount of fuel attached to the wall surface due to blow-back is caused. In addition, it is difficult to accurately estimate the amount of fuel adhering to the wall that has increased due to such blowback, and further, the amount of fuel adhering to the wall that has increased due to the increase in fuel gradually peels off and is taken away into the combustion chamber 12. This disturbs the air-fuel ratio in the subsequent combustion cycle. Therefore, in the system of this embodiment, regardless of the length of the valve overlap period, that is, regardless of the attenuation amount of the EGR gas amount, in order to precisely control the air-fuel ratio at the time of return from the deceleration F / C, the following The ECU 50 is caused to execute the routine shown in FIG.

Next, specific processing in the first embodiment will be described with reference to FIGS.
FIG. 2 is a flowchart of a routine executed by the ECU 50 in the first embodiment to satisfy the above request. Note that this routine is periodically executed for each cylinder at a certain crank angle. In the routine shown in FIG. 2, it is first determined whether or not the F / C during deceleration is being executed (step 100).

  As a result, if it is determined that the F / C is being performed, it is determined whether or not there is an F / C return request (step 102). Specifically, whether or not there is an acceleration request is determined based on the accelerator pedal opening PA. Next, the valve overlap amount is acquired based on the VVT advance value of the intake valve 24 when the return request is detected (step 104). Next, it is determined whether or not the valve overlap amount acquired in step 104 is larger than a determination value X (step 106).

  FIG. 3 is a diagram for explaining the fuel supply timing set for the first time when the F / C is restored in the routine shown in FIG. More specifically, the vertical axis in FIG. 3 indicates the end of fuel supply timing. As shown in FIG. 3, in the present embodiment, the initial fuel supply timing at the time of F / C return is switched according to the value of the valve overlap amount at the time of F / C return. In the setting shown in FIG. 3, when the valve overlap amount is equal to or less than the determination value X, the end of the fuel supply timing is set to 60 ° BTDC, which is the same as the normal time, in order to execute the intake asynchronous injection. On the other hand, when the valve overlap amount is larger than the determination value X, the final period is set to 30 ° ATDC in order to execute the intake synchronous injection. During the valve overlap period, the reflow is being performed right, and even if the fuel is injected when the influence of such a reflow is great, the fuel is blown off and the amount of fuel attached to the wall surface increases. The determination value X of the valve overlap amount in FIG. 3 is a value for determining whether or not the influence of such blowback is at a level that does not cause a problem in executing asynchronous injection.

  If it is determined in step 106 that the valve overlap amount at the time of F / C return> the determination value X is not satisfied, the end of the first fuel supply timing at the time of F / C return is 60 ° BTDC. (Step 108). That is, in this case, the delay of the fuel supply timing is not executed. Next, the recovery process from F / C is executed, that is, fuel injection is resumed (step 110).

  On the other hand, if it is determined in step 106 that the valve overlap amount at the time of F / C return> the determination value X is satisfied, the end of the first fuel supply timing at the time of F / C return is 30 ° ATDC. (Step 112). That is, the fuel supply timing is retarded to the intake synchronization side. Next, the injection timing retard flag is turned ON (step 114). Next, a return process from the F / C is executed (step 116).

  According to the processing of steps 106 and 108 or 112 described above, by determining the state of the attenuation amount of the EGR gas amount based on the VVT advance value, the amount of VVT control delay is taken into account from the F / C. It is possible to determine the amount of attenuation when returning. For this reason, the fuel supply timing can be set more precisely in accordance with the return amount of the valve valve overlap amount.

  In the routine shown in FIG. 2, when the F / C is not being executed, or when the processing cycle is after the F / C is being executed and a return request is made, the injection timing retard flag is turned ON. As long as there is, the determination in step 118 is not established. As described above, when the determination at step 118 is not established, and after the return processing from the F / C is executed at step 116, the valve overlap amount at the present time is reacquired (step 120). ).

  Next, it is determined whether or not the injection timing (fuel supply timing) retarded to the intake synchronization side by the process of step 112 has returned to the injection timing before the process of step 112 (step 122). ). As a result, when it is determined that the return of the injection timing has not been completed, the return amount of the injection timing is calculated (step 124). FIG. 4 is an example of a map stored in the ECU 50 in order to acquire the return amount of the injection timing. According to the map shown in FIG. 4, the retard amount of the injection timing is gradually set to a smaller value as the valve overlap amount becomes smaller, that is, as the attenuation of the EGR gas progresses. In this step 124, the ECU 50 refers to such a map, and calculates a return amount (retard amount) of the injection timing based on the valve overlap amount reacquired in the above step 120.

Next, the injection timing is set to the injection timing based on the return amount calculated in step 124 (step 126).
On the other hand, when it is determined in step 122 that the return of the injection timing has been completed, the injection timing retard flag is turned OFF (step 128).

  As described above, according to the routine shown in FIG. 2, when the valve overlap amount at the time of F / C return is equal to or smaller than the determination value X, that is, when the attenuation amount of the EGR gas is large, the influence of blowback is small. Therefore, the intake-synchronized injection capable of obtaining an air-fuel mixture in which fuel and fresh air are mixed well is selected. On the other hand, when the valve overlap amount at the time of F / C recovery is larger than the determination value X, that is, when the attenuation amount of EGR gas is small, the fuel supply timing is retarded to the intake synchronization side. According to the intake synchronous injection, the problem of an increase in the amount of fuel adhering to the wall surface due to blow-back is less likely to occur as compared with the intake asynchronous injection, and the fuel can be supplied directly into the combustion chamber 12. For this reason, according to the system of the present embodiment, the air-fuel ratio at the time of return from the deceleration F / C can be precisely controlled to a target value. Thereby, it is possible to effectively prevent the air-fuel ratio from becoming lean at the time of return, and it is possible to avoid occurrence of problems such as engine stall.

  Further, according to the routine shown in FIG. 2, after the delay of the fuel supply timing to the intake-synchronization side is completed, the fuel supply timing is set for each processing cycle of this routine so that the supply timing before the delay is reached. It is gradually returned to. According to such a method, it is possible to suppress a sudden change in the air-fuel ratio when returning the fuel supply timing.

  By the way, in the first embodiment described above, the valve overlap amount at the time of F / C return is compared with the determination value X to determine whether to retard the fuel supply timing to the intake synchronization side. Although the fuel supply timing is set according to the attenuation amount of the EGR gas, the method for determining the fuel supply timing according to the attenuation amount of the EGR gas in the present invention is not limited to this. For example, as the valve overlap amount is larger, that is, as the attenuation amount of EGR gas is smaller, the fuel supply timing may be delayed more toward the intake synchronization side.

In the first embodiment described above, the ECU 50 executes F / C when the internal combustion engine 10 is decelerated, so that the “fuel cut means” in the first invention drives the intake variable valve mechanism 42. By increasing or decreasing the internal EGR amount, the “EGR control means” in the first invention and the “variable valve timing control means” in the second invention execute the processing of step 104 or 120 described above, thereby The “fuel supply timing control means” according to the first aspect of the present invention is implemented by the “EGR attenuation amount acquisition means” according to the first aspect of the invention executing the processing of step 106, 108, or 112 described above.
In the first embodiment described above, the ECU 50 executes the process of step 104, so that the “valve timing control amount acquisition means” in the third aspect of the invention executes the process of step 106. The “EGR amount determining means” in the third aspect of the invention is realized.

Embodiment 2. FIG.
Next, a second embodiment of the present invention will be described with reference to FIGS.
FIG. 5 is a diagram for explaining the configuration of the second embodiment of the present invention. In FIG. 5, the same components as those shown in FIG. 1 are denoted by the same reference numerals, and description thereof is omitted or simplified.

  The system of the internal combustion engine 60 shown in FIG. 5 includes an exhaust gas recirculation passage 62 that connects the intake passage 14 and the exhaust passage 16. In the middle of the exhaust gas recirculation passage 62, an EGR valve 64 is provided. Further, the exhaust gas recirculation passage 62 is provided with an exhaust gas cooler (EGR cooler) 66 for cooling the exhaust gas recirculated to the intake passage 14. The system shown in FIG. 5 has these configurations, and the intake valve 24 and the exhaust valve 26 are driven to open and close by respective valve mechanisms not shown so that a single valve opening characteristic can be obtained. Except for the point, it has the same configuration as the system shown in FIG. Then, the ECU 68 appropriately controls the opening degree of the EGR valve 64 during execution of the F / C during deceleration so that the exhaust gas is recirculated to the combustion chamber 12 via the intake passage 14 (so-called external EGR control). In the present embodiment, the catalyst deterioration suppression control is also executed.

[Characteristics of Embodiment 2]
When the above-described catalyst deterioration suppression control is executed using the external EGR control with the throttle opening degree TA sufficiently reduced, the intake passage 14 is more controlled as the opening degree of the EGR valve 64 is controlled to be smaller. Since the amount of EGR gas introduced into the engine becomes smaller, the intake pipe pressure becomes more negative. When the intake pipe pressure is further reduced to a negative pressure, the blow back amount to the intake passage 14 is increased. Therefore, in a situation where the opening degree of the EGR valve 64 is controlled to be small in order to attenuate the amount of EGR gas when returning from the deceleration F / C, the opening degree of the EGR valve 64 is controlled to be smaller. The more the sound is attenuated, the larger the blowback amount.

  As a result, the larger the attenuation amount of the EGR gas, the more the amount of fuel adhering to the wall surface at the time of the first fuel injection at the time of the F / C return, and the air-fuel ratio in the first cycle of the return becomes lean. The air-fuel ratio is disturbed until the amount of fuel adhered to the wall surface and the amount taken away into the cylinder are stabilized. Therefore, in the system of the present embodiment, the ECU 68 executes the routine shown in FIG. 6 below in order to precisely control the air-fuel ratio at the time of return from the deceleration F / C regardless of the state of the attenuation amount of the EGR gas. It was decided.

Next, specific processing in the second embodiment will be described with reference to FIGS.
FIG. 6 is a flowchart of a routine executed by the ECU 68 in the second embodiment to satisfy the above request. Note that this routine is periodically executed for each cylinder at a certain crank angle. In FIG. 6, the same steps as those shown in FIG. 2 in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted or simplified.

  In the routine shown in FIG. 6, when a return request is detected during execution of F / C during deceleration (step 102), the actual EGR valve opening when the return request is detected is acquired (step 200). By acquiring the actual EGR valve opening degree by the processing of this step 200, the attenuation amount of the EGR gas when the F / C return request is detected can be grasped. Next, based on the actual EGR valve opening obtained in step 200, the retard amount of the injection timing used for the first fuel injection at the time of F / C return is calculated (step 202). The ECU 68 stores a map that defines the injection retardation amount in relation to the actual EGR valve opening. FIG. 7 is an example of such a map. According to the map shown in FIG. 7, the smaller the actual EGR valve opening is, the larger the injection retard amount is set.

  Next, the retard of the injection timing is executed based on the injection retard amount calculated in step 202 (step 204). Next, the injection timing retard flag is turned on (step 114), and after the fuel injection is resumed (step 116), the actual actual EGR valve opening is reacquired (step 206). Thereafter, until the return to the injection timing before the retard is completed, the return amount (retard amount) of the injection timing calculated based on the actual EGR valve opening re-acquired in step 206 (step 208). ), The injection timing is gradually returned (step 210).

  As described above, according to the routine shown in FIG. 6, the fuel supply timing is more retarded on the intake synchronization side as the actual EGR valve opening is smaller, that is, as the attenuation amount of the EGR gas is larger. For this reason, according to the system of the present embodiment, even when the above-described catalyst deterioration suppression control is executed using the external EGR control with the throttle opening degree TA sufficiently reduced, the deceleration F / Regardless of the change in the effect of blowback due to the difference in the attenuation amount of EGR gas when returning from C, it becomes possible to precisely control the air-fuel ratio at the time of return to a target value.

  In the above-described second embodiment, the ECU 68 adjusts the opening degree of the EGR valve 64 to increase or decrease the external EGR gas amount, thereby realizing the “EGR valve control means” in the second aspect of the invention. Further, the “intake air amount control means” according to the fifth aspect of the present invention is realized by the ECU 68 controlling the throttle valve 18 to the fully closed position during execution of the F / C during deceleration of the internal combustion engine 60.

It is a figure for demonstrating the structure of Embodiment 1 of this invention. It is a flowchart of the routine performed in Embodiment 1 of the present invention. FIG. 3 is a diagram for explaining a fuel supply timing set for the first time when the F / C is restored in the routine shown in FIG. 2. It is an example of the map referred in the routine shown in FIG. 2, in order to acquire the return amount of injection timing. It is a figure for demonstrating the structure of Embodiment 2 of this invention. It is a flowchart of the routine performed in Embodiment 2 of this invention. FIG. 7 is an example of a map that is referred to in the routine shown in FIG. 6 in order to acquire the return amount of the injection timing.

Explanation of symbols

10, 60 Internal combustion engine 14 Intake passage 16 Exhaust passage 18 Electronically controlled throttle valve 22 Fuel injection valve 28 Intake variable valve mechanism (VVT) mechanism 50, 68 ECU (Electronic Control Unit)
62 Exhaust gas recirculation passage 64 EGR valve

Claims (6)

A control device for an internal combustion engine, comprising fuel cut means for stopping fuel supply and EGR control means for controlling an exhaust gas recirculation amount, and performing fuel cut during deceleration to increase the exhaust gas recirculation amount. ,
EGR attenuation amount acquisition means for acquiring the attenuation amount of the exhaust gas recirculation amount;
A fuel supply timing control means for controlling the fuel supply timing;
The control device for an internal combustion engine, wherein the fuel supply timing control means determines the fuel supply timing according to the attenuation amount of the exhaust gas recirculation amount when the fuel supply is restarted from the fuel cut. . The EGR control means includes
Variable valve timing control means for driving a variable valve mechanism that varies the valve overlap period in which the intake valve opening period and the exhaust valve opening period overlap to vary the internal exhaust gas recirculation amount, the intake passage and the exhaust 2. An EGR valve control means for adjusting an opening degree of an EGR valve provided in the middle of an exhaust gas recirculation passage communicating with the passage to increase or decrease an external exhaust gas recirculation amount. Control device for internal combustion engine. The EGR control means is the variable valve timing control means,
The EGR attenuation amount acquisition means includes valve timing control amount acquisition means for acquiring an advance value of valve timing,
The fuel supply timing control means includes an EGR amount judgment means for judging a state of an attenuation amount of the exhaust gas recirculation amount when the fuel supply is resumed based on an advance value of the valve timing. Item 3. A control device for an internal combustion engine according to Item 2. The EGR control means is the variable valve timing control means,
The fuel supply timing control means delays the fuel supply timing at the time of restarting the fuel supply toward the intake synchronization side more greatly as the attenuation amount of the exhaust gas recirculation amount at the time of restarting the fuel supply is smaller. The control apparatus for an internal combustion engine according to claim 2 or 3, characterized by the above. An intake air amount control means for controlling the intake air amount, further attenuates the intake air amount when the fuel is cut, and the EGR control means is the EGR valve control means,
The fuel supply timing control means controls the fuel supply timing at the time of resuming the fuel supply to the intake synchronization side when the attenuation amount of the exhaust gas recirculation amount at the time of resuming the fuel supply is large. The control apparatus for an internal combustion engine according to claim 2. The fuel supply timing control means gradually returns the fuel supply timing to the supply timing before the control to the intake synchronization side when the control of the fuel supply timing to the intake synchronization side is completed. The control device for an internal combustion engine according to any one of claims 3 to 5.

Images