JP2012057488A - Control device of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control device of an internal combustion engine that properly controls an engine, regardless of reduction in an exhaust recirculating volume associated with performing a large number of purges.SOLUTION: An electronic control unit 22 calculates a base value of knocking limit at ignition timing on the basis of an engine speed and an engine load, and corrects the base value according to a purging air flow which is introduced in intake air to calculate the knocking limit at ignition timing.

Description

  The present invention relates to a fuel vapor processing system that discharges collected fuel vapor together with air into the intake air downstream of the air flow meter for processing, and an exhaust gas recirculation that recirculates a portion of the exhaust gas into the intake air using negative intake pressure. The present invention relates to a control device applied to an internal combustion engine including a circulation system.

  As a system mounted on an onboard internal combustion engine, fuel vapor generated in a fuel tank is collected in an adsorbent built in the canister, and the collected fuel vapor is desorbed (purged) from the adsorbent, Fuel vapor processing systems are known that release and process with air during intake air downstream of the air flow meter. In an internal combustion engine equipped with such a fuel vapor processing system, when fuel vapor is purged, excess fuel is supplied into the cylinder by the amount of fuel vapor contained in the purge gas, and the air-fuel ratio becomes overrich. End up.

  Therefore, conventionally, in an in-vehicle internal combustion engine equipped with a fuel vapor processing system, for example, as seen in Patent Document 1, the amount of fuel supplied excessively into the cylinder by purging the fuel vapor is obtained, and that amount is injected from the injector. By reducing the amount of fuel to be reduced, over-riching of the air-fuel ratio accompanying the purge of fuel vapor is suppressed. The fuel reduction correction amount at this time is obtained from the estimated value of the purge gas fuel concentration and the amount of purge gas.

JP 7-34921 A

  By the way, purging of fuel vapor is performed using intake negative pressure. Therefore, the purge of fuel vapor is performed during low load operation with a large intake negative pressure. However, in a hybrid vehicle having two power sources, an internal combustion engine and a motor, the low-efficiency operation of the low-efficiency internal combustion engine is avoided, so the opportunity for purging the fuel vapor is limited. ing. Therefore, in a hybrid vehicle equipped with a fuel vapor processing system, a large amount of purge is performed at a time so that the fuel vapor can be completely processed on a limited occasion.

  On the other hand, an exhaust gas recirculation system that recirculates a part of exhaust gas into intake air by using an intake negative pressure is known as a system mounted on an in-vehicle internal combustion engine. In the past, exhaust gas recirculation was mainly done for the purpose of slowing down combustion and reducing NOx emissions, but recently, for the purpose of increasing the compression ratio of internal combustion engines and improving fuel efficiency, A larger amount of exhaust gas recirculation is being performed.

  In an internal combustion engine that performs such a large amount of exhaust gas recirculation, the following problems occur when the large amount of purge is performed as described above. That is, if a large amount of fuel vapor is purged during exhaust gas recirculation, the gas flow rate in the intake passage increases by the amount of purge gas introduced, and the negative intake pressure decreases, resulting in exhaust gas recirculation. The amount will decrease. Therefore, in such an internal combustion engine, when a large amount of purge is performed, only an exhaust gas recirculation amount less than expected can be obtained.

  Further, when the exhaust gas is recirculated, the combustion is slowed accordingly. Therefore, in an internal combustion engine equipped with an exhaust gas recirculation system, control is performed to advance the ignition timing in accordance with the exhaust gas recirculation. Since the advance of the ignition timing is performed on the assumption that recirculated exhaust gas is introduced as expected, if the amount of exhaust gas recirculation is less than expected, the ignition timing will be over-advanced. .

  Further, when the intake air temperature becomes higher, knocking is likely to occur. Therefore, in many internal combustion engines, the intake air temperature of the ignition timing is corrected. The correction of the intake air temperature at the ignition timing may be overcorrected if there is an increase in the actual intake air amount due to a large amount of purge or a difference in prospect of the exhaust gas recirculation amount.

  Further, in the low-speed operation region of the internal combustion engine, the intake negative pressure is particularly increased in order to suppress vibration and noise, and the purge amount of fuel vapor is increased, so that a large amount of exhaust gas recirculation is expected. Therefore, in the low rotation operation region, the above problem is particularly remarkable.

Such a problem is not limited to a hybrid vehicle, and can occur similarly in an internal combustion engine that implements a large amount of recirculated exhaust gas and a large amount of purge.
The present invention has been made in view of such circumstances, and the problem to be solved is an internal combustion engine that can suitably perform engine control regardless of a decrease in the amount of exhaust gas recirculation accompanying the execution of mass purge. It is to provide a control device.

(Claim 1)
According to the first aspect of the present invention, a fuel vapor processing system that discharges and processes the collected fuel vapor together with air into the intake air downstream of the air flow meter, and a part of the exhaust gas during intake using the negative intake pressure. A control device applied to an internal combustion engine provided with an exhaust gas recirculation system for recirculation is presupposed. In such an internal combustion engine, if a large amount of purge is performed, the intake negative pressure decreases, and the exhaust gas recirculation amount as expected cannot be obtained. As a result, an inappropriate value may be set for the engine control parameter having a correlation with the exhaust gas recirculation amount.

  Therefore, in the first aspect of the invention, an engine control parameter having a correlation with the exhaust gas recirculation amount is calculated based on the amount of purge gas introduced into the intake air, the engine rotational speed, and the engine load. Yes. When a large amount of purge gas is introduced, the intake negative pressure downstream of the throttle is reduced accordingly, and the exhaust gas recirculation amount is reduced. On the other hand, many of the engine control parameters are calculated based on the engine speed and engine load. However, the calculation assumes that exhaust gas recirculation is performed as expected at the current engine speed and engine load. Has been made. For this reason, if the exhaust gas recirculation amount is reduced more than expected due to a large amount of purge, a value assuming an exhaust exhaust gas recirculation amount larger than the actual value is set as the engine control parameter.

  In this regard, in the invention described in claim 1, the engine control parameter having a correlation with the exhaust gas recirculation amount is calculated based on the amount of purge gas introduced into the intake air, the engine rotational speed, and the engine load. Therefore, engine control parameters can be set in consideration of a decrease in the exhaust gas recirculation amount associated with the large purge, and the engine control is preferably performed regardless of the decrease in the exhaust gas recirculation amount associated with the large purge. Will be able to.

(Claim 2)
According to the second aspect of the present invention, a fuel vapor processing system that discharges and processes the collected fuel vapor together with air into the intake air downstream of the air flow meter, and a part of the exhaust gas during intake using the negative intake pressure. A control device applied to an internal combustion engine provided with an exhaust gas recirculation system for recirculation is presupposed. In such an internal combustion engine, if a large amount of purge is performed, the intake negative pressure decreases, and the exhaust gas recirculation amount as expected cannot be obtained. As a result, an inappropriate value may be set for the engine control parameter having a correlation with the exhaust gas recirculation amount.

  In that respect, in the invention described in claim 2, the engine control parameter having a correlation with the exhaust gas recirculation amount is calculated based on the engine rotational speed and the engine load, and according to the amount of purge gas introduced into the intake air. The engine control parameters are corrected. Therefore, the engine control parameter can be set in consideration of the decrease in the exhaust gas recirculation amount due to the large purge, and the engine control can be suitably performed regardless of the decrease in the exhaust gas recirculation amount due to the large purge. become able to.

(Claim 3)
According to a third aspect of the present invention, there is provided a fuel vapor processing system that discharges and collects the collected fuel vapor together with air into the intake air downstream of the air flow meter, and a part of the exhaust gas during intake using the negative intake pressure. A control device applied to an internal combustion engine provided with an exhaust gas recirculation system for recirculation is presupposed. In such an internal combustion engine, if a large amount of purge is performed, the intake negative pressure decreases, and the exhaust gas recirculation amount as expected cannot be obtained. As a result, the ignition timing that is set on the assumption that the expected amount of exhaust gas recirculation can be obtained may be over-advanced. That is, if the exhaust gas recirculation amount is large, the combustion becomes slow and the timing at which the combustion pressure reaches a peak is delayed. Therefore, it is necessary to advance the ignition timing accordingly. However, if a large amount of purge gas is introduced, the intake negative pressure downstream of the throttle will be reduced accordingly, and the exhaust gas recirculation amount will decrease, so the ignition timing is set assuming a larger exhaust gas recirculation amount. Will come to be.

  Therefore, in the invention described in claim 3, the ignition timing is calculated based on the amount of purge gas introduced into the intake air, the engine speed, and the engine load. Therefore, it is possible to set the ignition timing in consideration of the decrease in the exhaust gas recirculation amount due to the large purge, and it is preferable to set the appropriate ignition timing regardless of the decrease in the exhaust gas recirculation amount due to the large purge. It will be possible to perform engine control.

(Claim 4)
According to a fourth aspect of the present invention, there is provided a fuel vapor processing system that discharges and collects the collected fuel vapor together with air into the intake air downstream of the air flow meter, and a part of the exhaust gas during intake using the negative intake pressure. A control device applied to an internal combustion engine provided with an exhaust gas recirculation system for recirculation is presupposed. In such an internal combustion engine, if a large amount of purge is performed, the intake negative pressure decreases, and the exhaust gas recirculation amount as expected cannot be obtained. As a result, the ignition timing that is set on the assumption that the expected amount of exhaust gas recirculation can be obtained may be over-advanced. That is, if the exhaust gas recirculation amount is large, the combustion becomes slow and the timing at which the combustion pressure reaches a peak is delayed. Therefore, it is necessary to advance the ignition timing accordingly. However, when a large amount of purge gas is introduced, the intake negative pressure downstream of the throttle is reduced by that amount, and the exhaust gas recirculation amount is reduced. Therefore, the ignition timing is set assuming a larger exhaust gas recirculation amount. It will be set.

  Therefore, in the invention described in claim 4, the ignition timing is calculated based on the engine speed and the engine load, and the ignition timing is corrected according to the amount of purge gas introduced into the intake air. Therefore, it is possible to set the ignition timing in consideration of the decrease in the exhaust gas recirculation amount due to the large purge, and it is preferable to set the appropriate ignition timing regardless of the decrease in the exhaust gas recirculation amount due to the large purge. It will be possible to perform engine control.

(Claim 5)
According to the fifth aspect of the present invention, a fuel vapor processing system that discharges and processes the collected fuel vapor together with air into the intake air downstream of the air flow meter, and a part of the exhaust gas during intake using the negative intake pressure. A control device applied to an internal combustion engine provided with an exhaust gas recirculation system for recirculation is presupposed. In such an internal combustion engine, if a large amount of purge is performed, the intake negative pressure decreases, and the exhaust gas recirculation amount as expected cannot be obtained.

  When the intake air temperature is low, the combustion speed becomes slow. Therefore, the ignition timing is corrected according to the intake air temperature to compensate for the delay in the combustion speed. The intake air temperature correction amount at such ignition timing is also usually set on the assumption that the exhaust gas recirculation amount is as expected, so if the exhaust gas recirculation amount becomes less than expected due to the introduction of a large purge, it will be overcorrected. Will end up.

  Therefore, in order to solve the above problem, in the invention described in claim 5, the intake temperature correction amount of the ignition timing is calculated based on the amount of purge gas introduced into the intake air and the intake air temperature. Therefore, it is possible to set the intake temperature correction amount for the ignition timing in consideration of the decrease in the exhaust gas recirculation amount due to the large purge, and the appropriate ignition timing can be set regardless of the decrease in the exhaust gas recirculation amount due to the large purge. This makes it possible to perform engine control suitably.

(Claim 6)
According to the sixth aspect of the present invention, a fuel vapor processing system that releases and processes the collected fuel vapor together with air into the intake air downstream of the air flow meter, and a part of the exhaust gas during intake using the intake negative pressure A control device applied to an internal combustion engine provided with an exhaust gas recirculation system for recirculation is presupposed. In such an internal combustion engine, if a large amount of purge is performed, the intake negative pressure decreases, and the exhaust gas recirculation amount as expected cannot be obtained.

  When the intake air temperature is low, the combustion speed becomes slow. Therefore, the ignition timing is corrected according to the intake air temperature to compensate for the delay in the combustion speed. The intake air temperature correction amount at such ignition timing is also usually set on the assumption that the exhaust gas recirculation amount is as expected, so if the exhaust gas recirculation amount becomes less than expected due to the introduction of a large purge, it will be overcorrected. Will end up.

  Therefore, in the invention described in claim 6, the intake air temperature correction amount at the ignition timing is calculated based on the intake air temperature, and the intake air temperature correction amount is corrected according to the amount of purge gas introduced into the intake air. Yes. Therefore, it is possible to set the intake temperature correction amount for the ignition timing in consideration of the decrease in the exhaust gas recirculation amount due to the large purge, and the appropriate ignition timing can be set regardless of the decrease in the exhaust gas recirculation amount due to the large purge. This makes it possible to perform engine control suitably.

(Claim 7)
According to the seventh aspect of the present invention, a fuel vapor processing system that discharges and processes the collected fuel vapor together with air into the intake air downstream of the air flow meter, and a part of the exhaust gas during intake using the negative intake pressure. A control device applied to an internal combustion engine provided with an exhaust gas recirculation system for recirculation is presupposed. In an internal combustion engine that performs exhaust gas recirculation, the amount of exhaust gas recirculated into the intake air is controlled by adjusting the opening of the EGR valve. Here, when a large amount of purge is performed, the amount of gas flowing through the intake passage increases, and the intake negative pressure decreases. Therefore, even if the opening degree of the EGR valve is the same, the amount of exhaust gas recirculation decreases. It becomes like this. Therefore, if the opening degree of the EGR valve is set without assuming the purge of fuel vapor, the target exhaust gas recirculation amount cannot be obtained when large-scale purge is performed.

  Therefore, in the invention described in claim 7, the opening degree of the EGR valve for adjusting the exhaust gas recirculation amount is calculated based on the amount of purge gas introduced into the intake air, the engine rotational speed, and the engine load. . Therefore, the opening degree of the EGR valve can be set in consideration of the decrease in the exhaust gas recirculation amount due to the large purge, and the necessary exhaust gas recirculation amount is achieved regardless of the decrease in the exhaust gas recirculation amount due to the large purge. As a result, the engine can be controlled appropriately.

(Claim 8)
The invention according to claim 8 is a fuel vapor processing system that discharges collected fuel vapor together with air into the intake air downstream of the air flow meter, and a part of the exhaust gas during intake using negative intake pressure. A control device applied to an internal combustion engine provided with an exhaust gas recirculation system for recirculation is presupposed. In an internal combustion engine that performs exhaust gas recirculation, the amount of exhaust gas recirculated into the intake air is controlled by adjusting the opening of the EGR valve. Here, when a large amount of purge is performed, the amount of gas flowing through the intake passage increases, and the intake negative pressure decreases. Therefore, even if the opening of the EGR valve is the same, the amount of exhaust gas recirculation decreases It becomes like this. Therefore, if the opening degree of the EGR valve is set without assuming the purge of fuel vapor, the target exhaust gas recirculation amount cannot be obtained when large-scale purge is performed.

  Accordingly, in the invention described in claim 8, the opening degree of the EGR valve for adjusting the exhaust gas recirculation amount is calculated based on the engine rotational speed and the engine load, and the opening amount is determined according to the amount of purge gas introduced into the intake air. The opening of the EGR valve is corrected. Therefore, the opening degree of the EGR valve can be set in consideration of the decrease in the exhaust gas recirculation amount due to the large purge, and the necessary exhaust gas recirculation amount is achieved regardless of the decrease in the exhaust gas recirculation amount due to the large purge. As a result, the engine can be controlled appropriately.

(Claim 9)
In the control apparatus for an internal combustion engine of the present invention, the engine load index value is calculated using an intake system model that expresses the response of the intake air amount to the operation of the throttle valve as a mathematical expression, for example, according to claim 9. It is possible to use the volumetric efficiency of the internal combustion engine made.

1 is a schematic diagram schematically showing the configuration of an internal combustion engine to which a first embodiment of the present invention is applied. The flowchart which shows the process sequence of the EGR advance amount base value calculation routine applied to the embodiment. The flowchart which shows the process sequence of the intake air temperature correction amount calculation routine applied to 2nd Embodiment of this invention. The flowchart which shows the process sequence of the EGR opening degree calculation routine applied to 3rd Embodiment of this invention.

(First embodiment)
Hereinafter, an embodiment of a control device for an internal combustion engine according to the present invention will be described in detail with reference to FIGS. Note that the control device of the present embodiment is applied to an internal combustion engine mounted on a hybrid vehicle having two drive sources of an internal combustion engine and a motor.

FIG. 1 shows the configuration of an internal combustion engine to which the present embodiment is applied. As shown in the figure, the internal combustion engine includes an intake passage 1, a combustion chamber 2, and an exhaust passage 3.
In the intake passage 1 of the internal combustion engine, an air cleaner 4 for purifying the intake air, an intake air temperature sensor 5 for detecting the intake air temperature, and an air flow meter 6 for detecting the intake air flow are arranged in order from the upstream. . A throttle valve 8 that is driven by a throttle motor 7 to adjust the flow rate of intake air and an injector 9 that injects fuel into the intake air are disposed downstream of the air flow meter 6 in the intake passage 1. The intake passage 1 is connected to the combustion chamber 2 via an intake valve 10. Here, the intake valve 10 communicates the intake passage 1 and the combustion chamber 2 in response to opening, and shuts off the communication in response to closing.

The internal combustion engine is provided with a variable valve mechanism 11 that makes the opening / closing timing (valve timing) of the intake valve 10 variable.
The combustion chamber 2 is provided with a spark plug 12 for spark ignition of a mixture of fuel and air introduced into the combustion chamber 2. The combustion chamber 2 is connected to the exhaust passage 3 via an exhaust valve 13. Here, the exhaust valve 13 communicates the combustion chamber 2 and the exhaust passage 3 when the valve is opened, and shuts off the communication when the valve is closed.

  An air-fuel ratio sensor 14 that detects the oxygen concentration in the exhaust gas is disposed in the exhaust passage 3. Further, a catalytic converter 15 for purifying exhaust gas is disposed downstream of the air-fuel ratio sensor 14 in the exhaust passage 3.

  Such an internal combustion engine is provided with an exhaust gas recirculation (EGR) system that recirculates part of the exhaust gas into the intake air. The EGR system includes an EGR passage 16 that communicates the downstream side of the catalytic converter 15 in the exhaust passage 3 and the downstream side of the throttle valve 8 in the intake passage 1. The EGR passage 16 is provided with an EGR cooler 17 that cools the exhaust gas recirculated through the passage, and an EGR valve 18 that adjusts the exhaust gas recirculation amount.

  The internal combustion engine is also provided with a fuel vapor processing system that releases and processes fuel vapor generated in the fuel tank 19 together with air into the intake air downstream of the throttle valve 8. The fuel vapor processing system includes a canister 20 that adsorbs and collects fuel vapor generated in the fuel tank 19 and a purge valve 21 that adjusts the amount (mass) of purge gas introduced into the intake air, that is, the amount of purge air. Configured.

  Such an internal combustion engine is controlled by an electronic control unit 22. The electronic control unit 22 includes a central processing unit (CPU) that executes various arithmetic processes related to engine control, and a read-only memory (ROM) that stores programs and data for engine control. The electronic control unit 22 also includes a random access memory (RAM) that temporarily stores CPU calculation results, sensor detection results, and the like, and an input / output port (I / O) that functions as an interface that mediates external signal exchange. O).

  Detection signals from the intake air temperature sensor 5, the air flow meter 6, and the air / fuel ratio sensor 14 are input to the input port of the electronic control unit 22. Furthermore, at the input port of the electronic control unit 22, a crank position sensor 24 that detects the rotational phase of the crankshaft 23 that is the engine output shaft, a knock sensor 25 that detects the occurrence of knocking, and the opening of the throttle valve 8 are detected. Detection signals from the throttle sensor 26 and the like are also input.

  On the other hand, the output port of the electronic control unit 22 is connected to drive circuits for various actuators provided in each part of the internal combustion engine, such as the throttle motor 7, the injector 9, the variable valve mechanism 11, and the spark plug 12. The electronic control unit 22 controls the engine by outputting a command signal to the actuator drive circuit.

  In the present embodiment configured as described above, the electronic control unit 22 controls the EGR system as part of engine control. The control of the EGR system in the internal combustion engine is performed mainly for the purpose of improving the fuel consumption performance by increasing the compression ratio of the internal combustion engine by introducing the exhaust gas into the intake air. Therefore, in this internal combustion engine, a large amount of exhaust gas recirculation is performed as compared with a conventional general internal combustion engine that performs exhaust gas recirculation mainly for the purpose of slowing down combustion and reducing NOx emissions. It has become. Such control of the EGR system is performed by calculating the opening degree of the EGR valve 18 at which an optimum exhaust gas recirculation amount is obtained in the current engine operating state based on the engine speed and the engine load.

  In this embodiment, the fuel vapor processing system is also controlled as part of the engine control. The control of the fuel vapor processing system is performed for the purpose of purging the fuel vapor collected in the canister 20 at an appropriate timing, releasing it into the intake air, and processing it by combustion in the combustion chamber 2. Such purging of fuel vapor is performed during low load operation with a large intake negative pressure. However, in the hybrid vehicle to which the present embodiment is applied, basically, traveling by a motor is performed in a low load operation region where the efficiency of the internal combustion engine is low. Therefore, in this internal combustion engine, there are few opportunities for low-load operation, and a large amount of purge is performed at a time so that the fuel vapor can be completely processed at the limited opportunities.

  Further, in the present embodiment, the electronic control unit 22 also controls the ignition timing by the spark plug 12. The ignition timing is generally controlled in the following manner. That is, in the ignition timing control, the electronic control unit 22 calculates the MBT point and the knock limit point of the ignition timing. Here, the MBT point is an ignition timing at which the engine torque is maximum, and the knock limit point is an assumed value of the advance limit of the ignition timing that can prevent knocking. The ignition timing is set to a retarded value from the reference ignition timing until no knocking is observed, with the value on the retard side of either the MBT point or the knock limit point as the reference ignition timing. Yes.

  Here, when exhaust gas recirculation is performed by the EGR system, the combustion rate of the air-fuel mixture decreases due to the introduction of the exhaust gas. As a result, the knock limit point of the ignition timing changes to the advance side. Therefore, in this internal combustion engine, the advance correction of the knock limit point according to the exhaust gas recirculation amount is performed. As described above, the opening degree of the EGR valve 18 is calculated based on the engine rotational speed and the engine load, and the exhaust gas recirculation amount at each engine rotational speed and each engine load is a substantially fixed value. . Therefore, in a conventional general internal combustion engine control device, the advance angle correction amount of the knock limit point is calculated from the engine speed and the engine load.

  However, in this internal combustion engine that performs a large amount of purge, when the purge of fuel vapor is performed and a large amount of purge gas is introduced into the intake air, the intake air flow rate downstream of the throttle valve 8 into which the purge gas has merged increases. Negative pressure becomes smaller. As a result, the amount of exhaust gas recirculation performed using the intake negative pressure is greatly reduced. Therefore, if the advance angle correction amount for the knock limit point is set according to the exhaust gas recirculation amount, the exhaust gas recirculation amount will be less than expected when a large purge is performed. Point advance correction may be overcorrection.

  Therefore, in the present embodiment, the knock limit point of the ignition timing is set in consideration of the current purge air amount in addition to the engine rotational speed and the engine load. Then, by considering the purge air amount in the calculation of the knock limit point, the influence of the decrease in the exhaust gas recirculation amount associated with the purge is reflected in the ignition timing. Note that the purge air amount indicates the weight of the purge gas introduced into one cylinder in each combustion cycle.

  In the present embodiment, the volume efficiency ηv of the internal combustion engine is used as the index value of the engine load. The volumetric efficiency ηv is a parameter obtained by dividing the piston displacement air amount in each cylinder of the internal combustion engine by the actual intake air amount, and is also called “load factor”. Incidentally, in the present embodiment, the response of the intake air amount to the operation of the throttle valve 8 is modeled, and the volumetric efficiency ηv is calculated using an intake system model (also referred to as an air model) that expresses the response. .

  FIG. 2 shows a flowchart of a routine for calculating the EGR advance amount base value eaegrknokb of the knock limit point employed in the present embodiment. The EGR advance amount base value eaegrknob is a correction value used for calculation of the knock limit point of the ignition timing. The knock limit point is calculated based on the EGR advance amount base value calculated from the engine speed and the engine load. It is obtained by performing correction with the value eaegrknob. Note that the processing of this routine is repeatedly executed by the electronic control unit 22 every calculation period of the ignition timing.

  When the processing of this routine is started, first, in step S100, the volume efficiency ηv that is an index value of the engine load is calculated. This calculation is performed by dividing the piston displacement air amount kpa in each cylinder by the gradual change value klsm of the intake air amount obtained by the air model.

  In the subsequent step S101, the EGR correction advance amount aeggrknob is calculated. The EGR correction advance amount aegrknob is the advance correction amount of the knock limit point according to the exhaust gas recirculation. The calculation of the EGR correction advance amount aegrknokb is performed using a three-dimensional calculation map map1 of the engine rotational speed ne, the volume efficiency ηv, and the engine water temperature thw. In this embodiment, the knock limit correction amount is set as positive on the retard side, and a negative value is set for the EGR correction advance amount aeggrknob. The EGR correction advance amount aegrknob is basically set such that the absolute value thereof increases as the exhaust gas recirculation amount increases. Incidentally, in the present embodiment, different maps are used as the calculation map map1 for calculating the EGR correction advance amount aegrkknob when there is a request for advancement of the variable valve mechanism 11 and when there is no request for advancement. Yes.

  When the EGR correction advance amount aegrknokb is calculated, the purge correction delay amount apgrknok is calculated in the subsequent step S102. This calculation is performed using a two-dimensional calculation map map2 of the engine speed ne and the volume efficiency ηv. In the calculation map map2, among the operating points of the internal combustion engine defined by the engine rotational speed ne and the volumetric efficiency ηv, the operating point where the fuel vapor is not purged is indicated as the value of the purge correction retardation amount apgrknok. “0” is set. On the other hand, a positive value is set as the purge correction retardation amount apgrknok at the operating point where the purge is performed. As the purge air amount at the operating point is larger, a positive value having a larger absolute value is set as the purge correction retardation amount apgrknok. Incidentally, in the present embodiment, when calculating the purge correction retardation amount apgrknok, different calculation maps are used depending on whether or not there is a request for advancement of the variable valve mechanism 11.

  When the EGR correction advance amount aegrknokb and the purge correction delay amount apgrknok are thus calculated, the EGR advance amount base value eaegrknokb is calculated in the subsequent step S103. Here, the EGR advance amount base value eaegrknob is calculated as an addition value of the EGR correction advance amount aegrknokb and the purge correction retard amount apgrknok.

  After executing the above processing, the electronic control unit 22 corrects the base value calculated from the engine rotational speed ne and the volumetric efficiency ηv with the EGR advance amount base value eaegrknokb. The electronic control unit 22 sets the corrected value as a knock limit point of the ignition timing, and executes the ignition timing control.

According to the control apparatus for an internal combustion engine of the present embodiment described above, the following effects can be obtained.
(1) In the present embodiment, the knock limit point of the ignition timing is calculated in consideration of the purge air amount at that time in addition to the engine speed and the engine load. That is, in the present embodiment, the ignition timing (knock limit point) is calculated based on the amount of purge air introduced into the intake air, the engine speed, and the engine load. More specifically, in the present embodiment, the ignition timing (knock limit point) is calculated based on the engine speed and the engine load, and the ignition timing (knock) according to the purge air amount introduced into the intake air is calculated. The limit point is corrected. Therefore, it is possible to set the ignition timing in consideration of the decrease in the exhaust gas recirculation amount due to the large purge, and it is preferable to set the appropriate ignition timing regardless of the decrease in the exhaust gas recirculation amount due to the large purge. It will be possible to perform engine control.

In addition, the said embodiment can also be changed and implemented as follows.
In the above embodiment, assuming that the purge air amount is uniquely determined from the engine rotational speed and the engine load (volumetric efficiency ηv), the ignition timing knock limit correction delay amount corresponding to the amount of purge air amount The (purge correction retardation amount apgrknok) is calculated from the engine rotational speed and the engine load (volumetric efficiency ηv). Even when such a premise does not hold, the current purge air amount can be detected or estimated, and the purge correction retardation amount apgrknok can be calculated based on the obtained purge air amount.

  In the above embodiment, the knock limit point of the ignition timing is obtained by correcting the base value obtained from the engine speed and the engine load (volumetric efficiency ηv) with the purge correction retardation amount apgrknok. However, it is also possible to directly obtain the knock limit point based on the purge air amount introduced into the intake air, the engine speed, and the engine load without performing such correction. Even in such a case, it is possible to set the ignition timing in consideration of the decrease in the exhaust gas recirculation amount due to the large purge, and the appropriate ignition timing can be set regardless of the decrease in the exhaust gas recirculation amount due to the large purge. The engine control can be suitably performed. In this case, the knock limit point is calculated using, for example, a three-dimensional calculation map based on the purge air amount, the engine rotational speed, and the engine load, or a four-dimensional calculation map obtained by adding the engine water temperature. Is possible.

  In the above embodiment, the knock limit point of the ignition timing is calculated in consideration of the purge air amount. However, if necessary, the same purge air amount is also considered for the MBT point of the ignition timing. Calculation may be performed. Further, the knock limit point and the MBT point can be obtained without considering the purge air amount, and the reference ignition timing set as the more retarded value can be corrected according to the purge air amount. Regardless of the decrease in the amount of exhaust gas recirculation that accompanies the purge, it is possible to set the appropriate ignition timing and perform engine control appropriately.

(Second Embodiment)
Next, a second embodiment in which the control device for an internal combustion engine of the present invention is embodied will be described in detail with reference to FIG. In the present embodiment, the same components as those in the above embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  In an internal combustion engine, when the intake air temperature is low, the combustion speed is slowed down. Therefore, correction of the ignition timing in accordance with the intake air temperature may compensate for the delay in the combustion speed. Therefore, in the present embodiment, during the warming-up of the internal combustion engine, the knock limit point of the ignition timing is corrected according to the intake air temperature. In the present embodiment, the intake air temperature correction amount related to such correction is calculated based on the intake air temperature tha and the map calculation air amount kl. The map calculation air amount kl is obtained as an average value of the look-ahead value of the intake air amount predicted by the above air model and the gradually changing value of the intake air amount.

  The intake air temperature correction amount at such ignition timing is also usually set on the assumption that the exhaust gas recirculation amount is as expected, so if the exhaust gas recirculation amount becomes less than expected due to the introduction of a large purge, it will be overcorrected. Will end up. Therefore, in this embodiment, when calculating the intake air temperature correction amount at the knock limit point, the purge air amount introduced into the intake air is also taken into consideration. More specifically, in the present embodiment, ignition is performed by correcting the base value calculated based on the intake air temperature tha and the map calculation air amount kl according to the purge air amount introduced into the intake air. The intake air temperature correction amount at the time is calculated.

  FIG. 3 is a flowchart of an intake air temperature correction amount calculation routine employed in this embodiment. The processing of this routine is repeatedly executed by the electronic control unit 22 every calculation period of the ignition timing.

When this routine is started, the electronic control unit 22 first calculates the map calculation air amount kl as an index value of the engine load in step S200.
In a succeeding step S201, it is determined whether or not exhaust gas recirculation is being executed. If exhaust gas recirculation is being executed (S201: YES), the process proceeds to step S202. If not (S201: NO), the process proceeds to step S203.

  When the process proceeds to step S202, in step S202, the intake air correction amount base value aknokthab is calculated with reference to the exhaust gas recirculation execution map map3. Here, the calculation map map3 is set as a two-dimensional map of the intake air temperature tha and the map calculation air amount kl. On the other hand, when the process proceeds to step 203, in step S203, the base value aknokthab of the intake air temperature correction amount is calculated with reference to the calculation map map4 for when exhaust gas recirculation is not executed. The calculation map map4 here is also set as a two-dimensional map of the intake air temperature tha and the map calculation air amount kl.

  When the base value aknokthab of the intake air temperature correction amount is thus calculated, the process proceeds to step S204. When the process proceeds to step S204, the current purge air amount is obtained from the engine speed ne and the engine load (for example, volumetric efficiency ηv) in step S204. In the subsequent step S205, the purge correction amount apgr of the intake air temperature correction amount is calculated based on the obtained purge air amount.

  In the subsequent step S206, the base value aknokthab is corrected with the purge correction amount apgr to calculate the final intake air temperature correction amount aknoktha. The intake air temperature correction amount aknoktha thus calculated is used for correction according to the intake air temperature at the knock limit point.

According to the control apparatus for an internal combustion engine of the present embodiment described above, the following effects can be obtained.
(1) In this embodiment, the intake air temperature correction amount aknoktha at the ignition timing (knock limit point) is calculated in consideration of the purge air amount. More specifically, in the present embodiment, the intake air temperature is obtained by correcting the base value aknokthab obtained from the map calculation air amount kl and the intake air temperature tha according to the purge air amount by the purge correction amount apgr. A correction amount aknoktha is calculated. Therefore, it is possible to set the intake temperature correction amount for the ignition timing in consideration of the decrease in the exhaust gas recirculation amount due to the large purge, and the appropriate ignition timing can be set regardless of the decrease in the exhaust gas recirculation amount due to the large purge. This makes it possible to perform engine control suitably.

In addition, the said embodiment can also be changed and implemented as follows.
In the above embodiment, the purge air amount is obtained from the engine speed and the engine load, and the purge correction amount apgr of the intake air temperature correction amount is calculated from the obtained purge air amount. However, if the purge air amount is uniquely determined from the engine rotational speed and the engine load, the purge air amount calculation is omitted, and the purge correction amount apgr is directly calculated from the engine rotational speed and the engine load. You can also

  In the above embodiment, the base value aknokthab obtained from the map calculation air amount kl and the intake air temperature tha is corrected with the purge correction amount apgr, so that the intake air temperature correction amount aknoktha at the knock limit point is obtained. It was. However, it is also possible to directly obtain the intake air temperature correction amount aknoktha based on the purge air amount introduced into the intake air and the intake air temperature without performing such correction. Even in such a case, it is possible to set the ignition timing in consideration of the decrease in the exhaust gas recirculation amount due to the large purge, and the appropriate ignition timing can be set regardless of the decrease in the exhaust gas recirculation amount due to the large purge. The engine control can be suitably performed. In this case, the intake air temperature correction amount aknoktha is calculated, for example, by adding a two-dimensional calculation map based on the purge air amount and the intake air temperature, or an engine load index value such as a map calculating air amount kl. It can be performed using a three-dimensional calculation map.

  In the above embodiment, the intake air temperature correction amount aknoktha at the knock limit point is calculated in consideration of the purge air amount. However, when the same intake air temperature correction is performed also at the MBT point of the ignition timing, The intake air temperature correction amount for the MBT point can be calculated in consideration of the purge air amount. Further, when the intake air temperature correction is performed at the reference ignition timing obtained as a value on the retard side of either the knock limit point or the MBT point, the intake air temperature correction amount for the reference ignition timing is obtained in consideration of the purge air amount. It can also be done.

  In the above embodiment, the map calculation air amount kl, which is obtained as an average value of the look-ahead value of the intake air amount predicted by the air model and the gradually changing value of the intake air amount, is used as the index value of the engine load. The intake air temperature correction amount aknoktha is calculated. In addition to the map calculation air amount kl, the engine load index value used for such calculation includes the look-ahead value of the intake air amount predicted by the air model, the gradually changing value of the intake air amount, or the intake air amount. A detection value or the like can also be used. It is also possible to calculate the intake air temperature correction amount aknoktha using the volume efficiency ηv (load factor) of the internal combustion engine as an index value of the engine load.

(Third embodiment)
Next, a third embodiment in which the control device for an internal combustion engine of the present invention is embodied will be described in detail with reference to FIG. In the present embodiment, the same components as those in the above embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  As described above, when a large amount of purge is performed, the intake negative pressure becomes small, and the exhaust gas recirculation amount becomes smaller than expected. Even in such a case, in order to obtain an exhaust gas recirculation amount as expected, it is necessary to increase the opening of the EGR valve 18 in accordance with the purge.

  Therefore, in the present embodiment, the exhaust gas recirculation associated with the purge is performed by calculating the opening of the EGR valve 18 based on the amount of purge gas introduced into the intake air in addition to the engine rotational speed and the engine load. The amount of decrease is compensated.

  FIG. 4 is a flowchart of a routine for calculating the opening degree (EGR opening degree) of the EGR valve 18 employed in the present embodiment. The processing of this routine is repeatedly executed by the electronic control unit 22 every calculation period of the EGR opening.

  When this routine is started, the electronic control unit 22 first determines the base value of the EGR opening in step S300 based on a two-dimensional calculation map of the engine speed and the engine load (for example, volumetric efficiency ηv). calculate. The base value calculated here is an EGR opening degree at which an optimal amount of exhaust gas can be recirculated in a state where the fuel vapor is not purged.

  In the subsequent step S301, the current purge air amount is obtained from the engine speed ne and the engine load (for example, volumetric efficiency ηv). In the subsequent step S302, the purge correction amount of the EGR opening is calculated based on the obtained purge air amount, and in the next step S303, the base value is corrected by the calculated purge correction amount. The final EGR opening is calculated. The electronic control unit 22 controls the EGR valve 18 based on the EGR opening calculated in this way, and executes an optimal amount of exhaust gas recirculation in accordance with the current engine operating conditions.

According to the control apparatus for an internal combustion engine of the present embodiment described above, the following effects can be obtained.
(1) In this embodiment, the opening degree of the EGR valve 18 that adjusts the exhaust gas recirculation amount is calculated based on the amount of purge gas introduced into the intake air, the engine speed, and the engine load. More specifically, the base value of the EGR opening is calculated based on the engine speed and the engine load, and the base value is corrected according to the amount of purge gas introduced into the intake air (purge air amount). Thus, the EGR opening degree is calculated. Therefore, the opening degree of the EGR valve can be set in consideration of the decrease in the exhaust gas recirculation amount due to the large purge, and the necessary exhaust gas recirculation amount is achieved regardless of the decrease in the exhaust gas recirculation amount due to the large purge. As a result, the engine can be controlled appropriately.

In addition, the said embodiment can also be changed and implemented as follows.
In the above embodiment, the purge air amount is obtained from the engine rotational speed and the engine load, and the purge correction amount for the EGR opening is calculated from the obtained purge air amount. However, if the purge air amount is uniquely determined from the engine rotation speed and the engine load, the purge air amount calculation is omitted, and the purge correction amount for the EGR opening is directly calculated from the engine rotation speed and the engine load. You can also do it.

  In the above embodiment, the EGR opening degree is obtained by correcting the base value obtained from the engine rotational speed and the engine load with the purge correction amount. However, it is also possible to directly obtain the EGR opening degree based on the purge air amount introduced into the intake air, the engine rotational speed, and the engine load without performing such correction. Even in such a case, it is possible to set the EGR opening in consideration of the decrease in the exhaust gas recirculation amount due to the large amount purge, and the necessary exhaust gas regardless of the decrease in the exhaust gas recirculation amount associated with the large amount purge. The recirculation amount can be secured and the engine control can be suitably performed. In this case, the EGR opening degree can be calculated using, for example, a three-dimensional calculation map based on the purge air amount, the engine rotational speed, and the engine load.

Further, each of the above embodiments can be modified as follows.
In each of the above embodiments, the purge air amount is used as an index value of the purge gas amount introduced into the intake air. Alternatively, a purge rate indicating the ratio of the mass of purge gas to the mass of all intake air can be used as an index value of the purge gas amount. Even in such a case, the ignition timing, the intake air temperature correction amount, and the EGR opening can be calculated in the same manner as in the above embodiments.

  In each of the above embodiments, the case where the ignition timing (knock limit point, etc.), the intake temperature correction amount, and the EGR opening are calculated in consideration of the amount of purge gas introduced during intake is described. However, the reduction in the exhaust gas recirculation amount due to the execution of the large purge affects all the engine control parameters that have a correlation with the exhaust gas recirculation amount. Therefore, even when calculating the engine control parameters, the amount of purge gas introduced into the intake air is taken into account, so that the engine control is suitably performed regardless of the decrease in the exhaust gas recirculation amount due to the large-scale purge. Will be able to do.

  -Although the control apparatus of the internal combustion engine which concerns on each said embodiment was applied to the internal combustion engine mounted in a hybrid vehicle, the control apparatus of this invention is an exhaust gas recirculation system and said fuel processing system. If it is an internal combustion engine provided with, it can apply similarly.

  DESCRIPTION OF SYMBOLS 1 ... Intake passage, 2 ... Combustion chamber, 3 ... Exhaust passage, 4 ... Air cleaner, 5 ... Intake temperature sensor, 6 ... Air flow meter, 7 ... Throttle motor, 8 ... Throttle valve, 9 ... Injector, 10 ... Intake valve, DESCRIPTION OF SYMBOLS 11 ... Variable valve mechanism, 12 ... Spark plug, 13 ... Exhaust valve, 14 ... Air-fuel ratio sensor, 15 ... Catalytic converter, 16 ... EGR passage, 17 ... EGR cooler, 18 ... EGR valve, 19 ... Fuel tank, 20 ... Canister, 21 ... purge valve, 22 ... electronic control unit, 23 ... crankshaft, 24 ... crank position sensor, 25 ... knock sensor, 26 ... throttle sensor.

Claims (9)

A fuel vapor processing system that discharges and collects the collected fuel vapor together with air into the intake air downstream of the air flow meter, and an exhaust gas recirculation system that recirculates part of the exhaust gas into the intake air using negative intake pressure. A control device applied to an internal combustion engine comprising:
A control device for an internal combustion engine, characterized in that an engine control parameter having a correlation with an exhaust gas recirculation amount is calculated based on an amount of purge gas introduced into intake air, an engine rotational speed, and an engine load. A fuel vapor processing system that discharges and collects the collected fuel vapor together with air into the intake air downstream of the air flow meter, and an exhaust gas recirculation system that recirculates part of the exhaust gas into the intake air using negative intake pressure. A control device applied to an internal combustion engine comprising:
The engine control parameter that correlates with the exhaust gas recirculation amount is calculated based on the engine speed and the engine load, and the engine control parameter is corrected according to the amount of purge gas introduced into the intake air. A control device for an internal combustion engine. A fuel vapor processing system that discharges and collects the collected fuel vapor together with air into the intake air downstream of the air flow meter, and an exhaust gas recirculation system that recirculates part of the exhaust gas into the intake air using negative intake pressure. A control device applied to an internal combustion engine comprising:
A control apparatus for an internal combustion engine, characterized in that an ignition timing is calculated based on an amount of purge gas introduced during intake, an engine speed, and an engine load. A fuel vapor processing system that discharges and collects the collected fuel vapor together with air into the intake air downstream of the air flow meter, and an exhaust gas recirculation system that recirculates part of the exhaust gas into the intake air using negative intake pressure. A control device applied to an internal combustion engine comprising:
A control device for an internal combustion engine, which calculates an ignition timing based on an engine rotation speed and an engine load, and corrects the ignition timing in accordance with an amount of purge gas introduced into intake air. A fuel vapor processing system that discharges and collects the collected fuel vapor together with air into the intake air downstream of the air flow meter, and an exhaust gas recirculation system that recirculates part of the exhaust gas into the intake air using negative intake pressure. A control device applied to an internal combustion engine comprising:
A control device for an internal combustion engine, characterized in that an intake air temperature correction amount for ignition timing is calculated based on an amount of purge gas introduced during intake air and an intake air temperature. A fuel vapor processing system that discharges and collects the collected fuel vapor together with air into the intake air downstream of the air flow meter, and an exhaust gas recirculation system that recirculates part of the exhaust gas into the intake air using negative intake pressure. A control device applied to an internal combustion engine comprising:
An internal combustion engine control apparatus characterized by calculating an intake air temperature correction amount at an ignition timing based on an intake air temperature and correcting the intake air temperature correction amount according to an amount of purge gas introduced into the intake air. A fuel vapor processing system that discharges and collects the collected fuel vapor together with air into the intake air downstream of the air flow meter, and an exhaust gas recirculation system that recirculates part of the exhaust gas into the intake air using negative intake pressure. A control device applied to an internal combustion engine comprising:
A control device for an internal combustion engine, wherein an opening degree of an EGR valve that adjusts an exhaust gas recirculation amount is calculated based on an amount of purge gas introduced during intake, an engine speed, and an engine load. A fuel vapor processing system that discharges and collects the collected fuel vapor together with air into the intake air downstream of the air flow meter, and an exhaust gas recirculation system that recirculates part of the exhaust gas into the intake air using negative intake pressure. A control device applied to an internal combustion engine comprising:
Calculate the opening degree of the EGR valve that adjusts the exhaust gas recirculation amount based on the engine speed and the engine load, and correct the opening degree of the EGR valve according to the amount of purge gas introduced into the intake air. A control device for an internal combustion engine characterized by the above. The volume efficiency of the internal combustion engine calculated using an intake system model that expresses the response of the intake air amount to the operation of the throttle valve as a mathematical expression is used as the index value of the engine load. The control apparatus of the internal combustion engine described in 1.

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