JP2006194115A - Control device of internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a control device of an internal combustion engine for refluxing exhaust gas in a combustion chamber during execution of fuelcut at deceleration, wherein sluggishness of the engine is improved when forced return from the fuelcut is incident to an abrupt acceleration request. <P>SOLUTION: A VVT response ΔVVT is learned each processing cycle (Step 102). When a F/C return request is made (Step 100) and an acceleration request from a driver is an abrupt acceleration request (Step 108), the fastest return point P1, namely the advance angle value of intake valve timing VVT allowing the fastest return from the F/C, is calculated on the basis of engine rotation speed NE and previous value of the VVT response ΔVVT (Steps 110, 112). When an actual VVT value is judged to pass through the fastest return point P1, the return from the F/C is executed (Step 116). <P>COPYRIGHT: (C)2006,JPO&NCIPI

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, in Patent Document 1, a transient operation state of an internal combustion engine, that is, rapid acceleration, slow acceleration, sudden deceleration, and slow deceleration is determined based on the throttle opening and the vehicle speed, and according to each state, A technique for appropriately controlling the amount of intake air is disclosed. More specifically, this technique increases the intake air amount by the intake pipe pressure variable means (supercharger) and also uses the valve timing variable means when it is determined that the engine is suddenly accelerated. By controlling the intake valve closing timing by the valve timing variable means to increase the intake air amount, the response delay of the air intake can be compensated.

Japanese Patent Laid-Open No. 10-9005 Japanese Patent Laid-Open No. 10-259747

  In an internal combustion engine, generally, when a predetermined condition is satisfied during a deceleration operation, fuel cut is executed to improve fuel consumption characteristics. When a sudden acceleration request is issued during execution of such fuel cut, the internal combustion engine is required to exhibit an excellent response to the acceleration request.

  By the way, from the viewpoint of suppressing deterioration of the catalyst disposed in the exhaust passage and suppressing excessive negative pressure of the intake pipe pressure, an internal combustion engine that performs control to recirculate exhaust gas into the combustion chamber during fuel cut during deceleration There is. In an internal combustion engine having such control, even if the forced recovery from the fuel cut is accompanied by a request for rapid acceleration, even if the intake air amount can be optimized by the technique of the above-mentioned Patent Document 1. If no consideration is given to the execution timing of forced return, the occurrence of misfire cannot be reliably suppressed. In other words, in the internal combustion engine having the control as described above, when it is forcibly returned from the fuel cut based on the accelerator request, the exhaust gas recirculation amount is surely attenuated to prevent the deterioration of combustion or misfire. After this is done, it is necessary to execute the forced return. However, on the other hand, when the forced return is accompanied by a request for rapid acceleration, there is a demand for minimizing engine slack by accelerating the forced return as much as possible.

  The present invention has been made to solve the above-described problems. In an internal combustion engine that recirculates exhaust gas into a combustion chamber during execution of fuel cut during deceleration, forced return from fuel cut is a request for rapid acceleration. An object of the present invention is to provide a control device for an internal combustion engine that can improve the engine slackness when accompanied.

In order to achieve the above object, the first invention comprises a fuel cut means for performing fuel cut when the internal combustion engine is decelerated, and an EGR control means for controlling the exhaust gas recirculation amount. A control device for an internal combustion engine that increases the exhaust gas recirculation amount by an EGR control means,
Forced return condition determination means for determining that a forced return condition from the fuel cut is satisfied based on an accelerator request detected during the fuel cut during deceleration;
Combustion possibility determination means for determining whether combustion can be resumed when the forced return condition is satisfied;
EGR damping means for driving the EGR control means so that the exhaust gas recirculation amount is attenuated when the forced return condition is satisfied;
Fuel injection restart execution means for restarting fuel injection when it is determined by the combustion possibility determination means that combustion can be restarted in the process in which the exhaust gas recirculation amount is attenuated by the EGR attenuation means;
Rapid acceleration request determination means for determining whether the establishment of the forced return condition is accompanied by a rapid acceleration request,
The fuel injection restart execution means, when it is determined that the establishment of the forced return condition is accompanied by a rapid acceleration request, the fuel injection restart execution time is advanced from the fuel restart restart determination time. To do.

  Further, the second invention is characterized in that, in the first invention, the fuel injection resumption execution means advances the fuel injection resumption time by a predetermined period from the combustion resumability judgment time.

  In a third aspect based on the second aspect, the fuel injection resumption executing means is configured such that the exhaust gas generated by the initial explosion after the forced return condition is satisfied in at least one cylinder is controlled by the EGR control during the predetermined period. It is characterized by comprising restart time setting means for setting so as to be a period until it is recirculated into the combustion chamber by the means.

Further, in a fourth invention according to any one of the first to third inventions, 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 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 fifth aspect based on the fourth aspect, the fuel injection resumption execution means determines a fuel injection resumption time based on at least one of a drive amount of the variable valve mechanism and an opening of the EGR valve. It is characterized by being advanced.

  According to the first invention, when the forced return from the fuel cut is accompanied by a rapid acceleration request, before the exhaust gas recirculation amount is attenuated to the region where it is determined that the combustion can be restarted. Fuel injection is resumed. For this reason, according to the present invention, it is possible to improve the engine slackness in response to the rapid acceleration request.

  According to the second invention, when the forced return from the fuel cut is accompanied by the rapid acceleration request, from the time when the exhaust gas recirculation amount is attenuated to the region where it is determined that the combustion can be resumed. Also, the fuel injection is resumed only a predetermined time ago. For this reason, according to the present invention, it is possible to improve the engine slackness in response to the rapid acceleration request.

  According to the third aspect of the present invention, the resumption of fuel injection can be started at an early stage only until the exhaust gas generated by the first explosion after the forced return condition is established is recirculated into the combustion chamber, and the combustion deteriorates or While suppressing the occurrence of misfire, it is possible to improve the engine's sluggishness in response to a rapid acceleration request.

  According to the fourth aspect of the present invention, it is possible to determine whether or not combustion can be restarted according to the state of attenuation of the internal exhaust gas recirculation amount or the external exhaust gas recirculation amount. Occurrence can be suppressed.

  According to the fifth aspect, since the restart point of fuel injection can be determined more accurately based on the driving amount of the variable valve mechanism or the opening of the EGR valve, the occurrence of misfire and the like can be more reliably performed. While suppressing, it is possible to improve the sluggishness of the engine in response to a rapid acceleration request.

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 the engine rotational speed NE. 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.

[Overview of catalyst deterioration suppression control]
The system of the present embodiment configured as described above is a process for stopping fuel injection when the throttle opening TA is set to the idle opening TA0 during the operation of the internal combustion engine 10, that is, a fuel cut (F / C). F / C is started when the throttle opening TA is suddenly closed during the operation of the internal combustion engine 10. For this reason, after the start of F / C, a state is formed in which the intake pipe pressure PM is large and easily becomes negative. At this time, if the intake pipe pressure PM becomes excessively negative, an increase in oil occurs in the internal combustion engine 10 and the amount of oil consumption increases.

  Incidentally, the negative pressure of the intake pipe pressure PM can be avoided by increasing the throttle opening degree TA. Therefore, if the throttle opening TA is maintained at an opening larger than the basic idle opening TA0 after the start of F / C, it is possible to prevent the intake pipe pressure PM from becoming excessively negative, that is, It is possible to prevent the oil from rising. However, 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. For this reason, if the throttle opening TA is opened after the start of F / C to increase the amount of lean gas flow, the increase in oil consumption can be prevented, but the deterioration of the upstream catalyst 36 and the downstream catalyst 38 is promoted.

  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 PM is in a negative pressure state, the amount of burned gas that flows back to the intake passage 14 after the intake valve 24 is opened, That is, the amount of internal EGR increases.

  The intake pipe pressure PM approaches the atmospheric pressure as the amount of gas downstream of the throttle valve 18 increases. The amount of gas is the sum of the amount of fresh gas that has passed through the throttle valve 18 and the amount of internal EGR gas generated during the valve overlap period. For this reason, if the internal EGR amount is sufficiently large, the intake pipe pressure PM will not be excessively negative, no matter how small the throttle opening TA is.

  As described above, according to the system shown in FIG. 1, if the throttle opening degree TA is sufficiently reduced in a state where a sufficient valve overlap is generated, a sufficient internal EGR amount can be generated. It is possible to effectively suppress the deterioration of the upstream catalyst 36 and the downstream catalyst 38 while preventing the oil from rising. Hereinafter, such control, that is, control for suppressing deterioration of the catalysts 36 and 38 by introducing EGR gas into the combustion chamber 12 during F / C during deceleration is referred to as “catalyst deterioration suppression control”.

[Characteristics of Embodiment 1]
FIG. 2 is a timing chart for explaining the operation of the first embodiment when a rapid acceleration request is issued under the situation where the catalyst deterioration suppression control is being executed during F / C. More specifically, FIG. 2 (A) shows a waveform indicating the success or failure of F / C execution, and FIG. 2 (B) shows a waveform indicating whether or not the accelerator pedal is in the idle position. ) Shows a waveform indicating whether or not the throttle valve 18 is in the idle position. Fig. 2 (D) is a diagram showing examples of changes in target VVT values and actual VVT values associated with F / C in relation to misfire limit values. Fig. 2 (E) is an actual accelerator associated with F / C. FIG. 2 (F) shows an example of changes in the opening degree PA (at the time of rapid acceleration), the target throttle opening degree TA, and the actual throttle opening degree TA. FIG. 2 (F) shows an intake pipe pressure PM and an acceleration sensor (G sensor) incorporated in the vehicle. An example of change is shown.

  As shown in FIG. 2B, when the accelerator pedal leaves the idle position during execution of F / C, an acceleration request is detected, and it is determined that the condition for forced return from F / C is satisfied. Thereafter, the following processing is executed toward the resumption of fuel injection. That is, when the forced return condition is established, the throttle opening TA is set to the idle opening TA0 (the “throttle waiting” state shown in FIG. 2E), and as shown in FIG. In order to return the advance value of the intake valve timing VVT, which has been advanced during the execution of the F / C to realize the internal EGR, to the set value in the normal combustion operation according to the operation state of the internal combustion engine 10, A timing delay request for timing VVT is issued. When the catalyst deterioration suppression control is being executed, the throttle opening degree TA is basically set to more reliably suppress the inflow of fresh air into the catalysts 36 and 38 when F / C is being executed. Fully closed. Since the variable valve mechanisms 28 and 30 are normally driven by hydraulic pressure, their responsiveness is not as good as that of the throttle valve 18. According to the above processing, the intake valve timing VVT is retarded by setting the throttle opening TA of the throttle valve 18 having better responsiveness than the intake variable valve mechanism 28 to the idle opening TA0. Moreover, it is possible to suppress the intake pipe pressure PM from becoming excessively negative.

  Further, when the forced return condition is established, the acceleration state is determined based on the actual accelerator opening PA as shown in FIG. The example of the operation illustrated in FIG. 2 illustrates an example in which it is determined that sudden acceleration is performed. Thereafter, the command value of the target throttle opening degree TAT is increased in accordance with the change amount of the actual accelerator opening degree PA, and the actual throttle opening degree TA is controlled to increase accordingly.

  As described above, when a request for retarding the intake valve timing VVT is issued, the actual VVT value is gradually retarded toward the retarded target VVT value (see FIG. 2D). However, as described above, the response of the intake variable valve mechanism 28 is not as good as that of the throttle valve 18. Therefore, the intake valve timing VVT by the intake variable valve mechanism 28 is controlled by the opening degree of the throttle valve 18. Response delay occurs with respect to control. If an attempt is made to immediately restart fuel injection under such a response delay, the internal EGR amount is not sufficiently attenuated, resulting in deterioration of combustion or misfire.

  For this reason, in order to suppress the occurrence of misfire, etc. when returning from F / C, wait for the actual VVT value to be retarded until the area where combustion is possible, and then return from F / C. There is a need to. That is, it is necessary to execute the return from the F / C after waiting for the actual VVT value to pass the misfire limit shown in FIG. However, when rapid acceleration is required as in the example shown in Fig. 2, to respond to such a request from the driver, return from F / C as much as possible while suppressing the occurrence of misfire. I want to minimize the sluggishness of the institution by speeding up.

  Here, the operation of the internal combustion engine when the fuel injection is resumed after the execution of F / C will be specifically described. During the execution of the F / C when the catalyst deterioration suppression control is being executed, the actual throttle opening degree TA is kept fully closed in order to more reliably suppress the inflow of fresh air into the catalysts 36 and 38. However, even if the actual throttle opening degree TA is in the fully closed position, the fresh air cannot be completely blocked due to the structure of the throttle valve 18. For this reason, the ratio of fresh air in the gas in the combustion chamber 12 gradually increases with the progress of F / C. That is, since the combustion is not performed while the F / C is being performed, the gas that sufficiently contains fresh air moves back and forth between the combustion chamber 12 and the intake passage 14.

  For this reason, the first combustion after the return from F / C (hereinafter may be abbreviated as “first explosion”) is very good, and there is no risk of misfire or the like. However, in the combustion after the first explosion, the burned gas generated by the first explosion is back blown into the intake pipe and then supplied into the combustion chamber 12 as EGR gas. In such a case, the actual VVT value If the delay angle is not sufficiently advanced, misfires may occur. In other words, if the actual VVT value exceeds the misfire limit before the burned gas generated by the first explosion is recirculated into the combustion chamber 12, the execution time of the F / C return is determined from the time when the misfire limit is reached. It means that the occurrence of misfire etc. can be prevented even if early.

  Therefore, in the present embodiment, when a rapid acceleration request is issued, the burned gas generated by the initial explosion after resuming combustion injection is recirculated and only re-intaked into the combustion chamber 12. It was decided to restart the fuel injection earlier than when the actual VVT value reached the misfire limit. According to such a method, as in this embodiment, when internal EGR control is performed as a method for introducing EGR gas into the F / C, the burnt gas generated by the first explosion is re-inhaled. In the period until the next combustion, that is, in the period corresponding to two revolutions in terms of the engine speed NE, it becomes possible to restart the fuel injection earlier than the time when the actual VVT value reaches the misfire limit value. . For this reason, according to the system of this embodiment, when the establishment of the forced return condition from the F / C is based on the rapid acceleration request, it is possible to improve the engine slack without causing misfire or the like. It becomes possible.

Next, specific processing in the first embodiment will be described with reference to FIGS.
FIG. 3 is a flowchart of a routine executed by the ECU 50 in the first embodiment to realize the above function. This routine is periodically executed at predetermined time intervals during execution of the F / C during deceleration. In the routine shown in FIG. 2, first, it is determined whether or not an F / C return request has been made (step 100). Specifically, whether or not there is an acceleration request is determined based on the accelerator pedal opening PA. As a result, if it is determined that an F / C return request has not been issued, the VVT response ΔVVT is acquired (step 102), and the current processing cycle is terminated. In step 102, the ECT 50 calculates the VVT response ΔVVT from the amount of change in the actual VVT value per predetermined time based on the output of the cam angle sensor 34 described above.

  On the other hand, if it is determined in step 100 that there is an F / C return request, that is, if the establishment of a forced return condition from F / C is recognized, the throttle opening TA is set to the idle opening TA0. At the same time as set (step 104), the intake variable valve timing (VVT) mechanism 28 retards the intake valve timing VVT to execute a process of attenuating the internal EGR (step 106). Specifically, the intake valve timing VVT is retarded at the maximum speed that the intake variable valve mechanism 28 can produce when it is recognized that there is an F / C return request.

  Next, it is determined whether or not the accelerator opening PA is larger than a predetermined high load region angle PA0 (step 108). Specifically, in this step 108, the degree of acceleration request is determined according to the degree of depression of the accelerator pedal, that is, it is determined whether or not the acceleration request from the driver requires rapid acceleration. Here, the change amount (depression amount) of the accelerator opening PA is compared with the high load region angle PA0 that is the determination threshold, but the determination method of the acceleration request is not limited to this, and the accelerator opening Instead of the change amount of PA or together with the accelerator opening degree PA, the determination may be made based on the change rate (depression speed) of the accelerator opening degree PA.

  If it is determined in step 108 that the accelerator pedal opening PA is smaller than the high load range angle PA0, that is, if it is determined that the acceleration is sudden acceleration, the previous values of the engine speed NE and the VVT response ΔVVT are acquired. (Step 110). Next, the fastest return point P1 from F / C is calculated (step 112). The fastest return point P1 is an advance value of the intake valve timing VVT that enables the fastest return from F / C, and the ECU 50 calculates a map shown in FIG. 4 in order to calculate such a fastest return point P1. Is remembered. The fastest return point P1 stored in this map is the advance angle of the intake valve timing VVT corresponding to two revolutions before the engine speed NE with respect to the advance value A of the intake valve timing VVT corresponding to the misfire limit value. It is set as a value. The advance value A itself can be calculated based on the operating state of the internal combustion engine 10 (load factor KL, engine speed NE, etc.).

  Specifically, the map shown in FIG. 4 defines the fastest return point P1 in relation to the VVT response ΔVVT and the engine speed NE. That is, in the map of FIG. 4, the fastest return point P1 is more advanced with respect to the advance value A as the VVT response ΔVVT is higher, that is, the change amount of the actual VVT value per predetermined time is larger. It is set to be the value of. In the map of FIG. 4, the fastest return point P1 is secured for a longer time corresponding to two engine revolutions NE as the engine revolution NE at the time of F / C restoration decreases. It is set to be a value on the advance side with respect to the advance value A. According to such a map setting, the fastest return point P1 is accurately obtained based on the response of the mechanism that attenuates EGR, in this case, the response of the intake variable valve mechanism 28 and the engine speed NE. Can do.

  Next, it is determined whether or not the actual VVT value has passed the fastest return point P1 (step 114). As a result, when it is determined that the actual VVT value has passed the fastest return point P1, the return process from the F / C is executed, that is, the fuel injection is restarted (step 116).

  As described above, according to the routine of FIG. 3, the restart timing of fuel injection is earlier than the actual VVT value reaches the advance value A corresponding to the misfire limit value by two engine revolutions NE. It is said. According to such processing, the actual VVT value reaches the advance value A before the burned gas generated by the first explosion is recirculated into the combustion chamber 12 even if the restart timing of fuel injection is advanced. It will be. For this reason, according to the system of this embodiment, when the forced return condition is satisfied by the rapid acceleration request, it is possible to improve the engine slack while suppressing the occurrence of misfire and the like.

  By the way, in the first embodiment described above, while the F / C is being executed, it is basically applied to the control in which the throttle opening degree TA is fully closed. The target is not limited to this, and control may be executed in which the throttle opening degree TA is opened by a predetermined amount during execution of F / C.

  In the first embodiment described above, the valve overlap period is changed by changing the state of the intake variable valve mechanism 28, and as a result, the internal EGR amount is changed. However, the internal EGR amount is changed. The technique to make is not limited to such a technique. For example, the valve overlap period may be changed by changing the state of the exhaust variable valve mechanism 30 and, as a result, the internal EGR amount may be changed.

  Further, the method of changing the internal EGR amount is not limited to the method of increasing or decreasing the valve overlap period. For example, when the closing timing of the exhaust valve 26 is set in the crank angle region before the exhaust top dead center, the amount of residual gas trapped in the combustion chamber 12 in the exhaust stroke is increased or decreased by moving the closing timing back and forth. To do. For this reason, the internal EGR amount may be increased or decreased by adjusting the closing timing of the exhaust valve 26 in the crank angle region before the exhaust top dead center.

In the first embodiment described above, the ECU 50 executes F / C during deceleration of the internal combustion engine so that the “fuel cut means” in the first invention drives the intake variable valve mechanism 28. By controlling the amount of internal EGR, the “EGR control means” in the first invention executes the processing of step 100, and the “forced return condition determination means” in the first invention results in the steps 112 and 112 described above. By executing the process 114, the “combustible determination means” in the first invention performs the process in step 106, and the “EGR attenuation means” in the first invention performs the process in step 116. By executing the process of step 108, the “fuel injection restart execution means” in the first invention executes the first invention. Definitive "rapid acceleration request determining means" is realized, respectively.
In the first embodiment described above, the “resumption time setting means” in the third aspect of the present invention is realized by the ECU 50 executing the processing of steps 110 and 112 described above.
In the first embodiment described above, the “variable valve timing control means” according to the fourth aspect of the present invention is implemented by driving the intake variable valve mechanism 28 to increase or decrease the internal EGR amount.

Embodiment 2. FIG.
Next, a second embodiment of the present invention will be described with reference to FIG. 5 and FIG.
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 shown in FIG. 5 includes an exhaust gas recirculation passage 64, an EGR valve 66, and an EGR cooler 68, and each of the intake valve 24 and the exhaust valve 26 is opened by a single valve opening mechanism (not shown). The system has the same configuration as that of the system shown in FIG. 1 except that it is opened and closed to obtain characteristics. Even in the system of the present embodiment in which external EGR control is executed, misfire or the like occurs when sudden acceleration is requested during forced recovery from the state in which the catalyst deterioration suppression control is being executed during F / C. The ECU 62 is caused to execute the following routine processing shown in FIG. 6 in order to improve engine shading while suppressing the engine.

  FIG. 6 is a flowchart of a routine executed by the ECU 62 in the second embodiment. This routine is periodically executed at predetermined time intervals during execution of the F / C during deceleration. In FIG. 6, the same steps as those shown in FIG. 3 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, during the F / C at the time of deceleration, while it is determined that an F / C return request has not yet been made (step 100), the EGR valve response ΔEGRV is acquired for each processing cycle (step 200). ). The EGR valve response ΔEGRV is calculated as a change amount of the actual EGR valve opening degree every predetermined time. On the other hand, when it is determined that the F / C return request has been made (step 100), the throttle opening degree TA is set to the idle opening degree TA0 (step 104) and the external operation performed during the F / C is performed. In order to attenuate EGR, a process for returning the opening degree of the EGR valve 66 to a set value corresponding to the operating state of the internal combustion engine 70 is started (step 202).

  Next, when it is determined that the accelerator request issued from the driver is a rapid acceleration request (step 108), the engine speed NE and the previous value of the EGR valve response ΔEGRV are acquired (step 204). Next, the fastest return point P2 from F / C is calculated (step 206). The fastest return point P2 is the opening degree of the EGR valve 66 that enables the fastest return from F / C, and the ECU 62 calculates the fastest return point P2 with reference to the map similar to FIG. 4 described above. .

  Next, it is determined whether or not the actual EGR valve opening has passed the fastest return point P2 (step 208). As a result, when it is determined that the actual EGR valve opening degree has passed the fastest return point P2, the return process from the F / C is executed, that is, the fuel injection is restarted (step 210). .

  As described above, according to the routine shown in FIG. 6, the timing for resuming the fuel injection is faster by two revolutions at the engine speed NE than when the actual EGR valve opening reaches the opening B corresponding to the misfire limit value. It is time. According to such a process, even if the restart execution timing of the fuel injection is advanced, the actual EGR valve opening degree reaches the opening degree B before the burned gas generated by the first explosion is recirculated into the combustion chamber 12. Will be. For this reason, according to the system of the present embodiment, misfire or the like occurs when the forced return condition is satisfied by the rapid acceleration request in the situation where the catalyst deterioration suppression control is executed by the external EGR control during F / C. It is possible to improve the engine slack while suppressing the occurrence of

  In the second embodiment described above, the “EGR valve control means” according to the fourth aspect of the present invention is realized by the ECU 62 adjusting the opening degree of the EGR valve 66 to increase or decrease the external EGR amount.

It is a figure for demonstrating the structure of Embodiment 1 of this invention. 6 is a timing chart for explaining the operation of the first embodiment when a rapid acceleration request is issued under the situation where the catalyst deterioration suppression control is being executed during F / C. It is a flowchart of the routine performed in Embodiment 1 of the present invention. 4 is a map of the fastest return point P1 referred to in the routine shown in FIG. 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.

Explanation of symbols

10, 60 Internal combustion engine 14 Intake passage 16 Exhaust passage 18 Electronically controlled throttle valve 20 Throttle position sensor 28 Intake variable valve mechanism (VVT) mechanism 30 Exhaust variable valve mechanism (VVT) mechanism 32 Crank angle sensor 34 Cam angle sensors 50, 62 ECU (Electronic Control Unit)
52 Accelerator position sensor 64 Exhaust gas recirculation passage 66 EGR valve

Claims (5)

An internal combustion engine having a fuel cut means for performing fuel cut during deceleration of the internal combustion engine and an EGR control means for controlling an exhaust gas recirculation amount, and increasing the exhaust gas recirculation amount by the EGR control means during a fuel cut during deceleration An engine control device,
Forced return condition determination means for determining that a forced return condition from the fuel cut is satisfied based on an accelerator request detected during the fuel cut during deceleration;
Combustion possibility determination means for determining whether combustion can be resumed when the forced return condition is satisfied;
EGR damping means for driving the EGR control means so that the exhaust gas recirculation amount is attenuated when the forced return condition is satisfied;
Fuel injection restart execution means for restarting fuel injection when it is determined by the combustion possibility determination means that combustion can be restarted in the process in which the exhaust gas recirculation amount is attenuated by the EGR attenuation means;
Rapid acceleration request determination means for determining whether the establishment of the forced return condition is accompanied by a rapid acceleration request,
The fuel injection restart execution means, when it is determined that the establishment of the forced return condition is accompanied by a rapid acceleration request, the fuel injection restart execution time is advanced from the fuel restart restart determination time. A control device for an internal combustion engine.   2. The control apparatus for an internal combustion engine according to claim 1, wherein the fuel injection resumption execution means advances the fuel injection resumption time by a predetermined period from the combustion resumability determination time.   The fuel injection restart execution means is the period until the exhaust gas generated by the first explosion after the forced return condition is satisfied in at least one cylinder is recirculated into the combustion chamber by the EGR control means. 3. The control apparatus for an internal combustion engine according to claim 2, further comprising a restart timing setting means for setting as described above. 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. The control apparatus for an internal combustion engine according to any one of claims 3 to 4. 5. The internal combustion engine according to claim 4, wherein the fuel injection restart execution means advances the restart point of fuel injection based on at least one of a drive amount of the variable valve mechanism and an opening of the EGR valve. Control device.

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