JP5644384B2 - Control device for internal combustion engine - Google Patents

Description

  The present invention relates to a control device for an internal combustion engine that performs feedback control of an idle rotation speed of the internal combustion engine so as to achieve a target idle rotation speed.

  As seen in Patent Document 1 and the like, in an onboard internal combustion engine or the like, feedback control of idle rotation speed, so-called ISC (Idol Speed Control) feedback, is performed so as to achieve a target idle rotation speed. In ISC feedback, the engine load (intake air amount or the like) is adjusted in accordance with the deviation between the actual idle speed and the target idle speed so that the actual idle speed approaches the target idle speed.

  Further, at the time of ISC feedback, the engine torque (ISC required torque) necessary for obtaining the target idle speed is obtained. Then, an ignition timing (ISC required ignition timing) at which the ISC required torque can be obtained is obtained, and the actual ignition timing is set as the ISC required ignition timing.

  By the way, depending on the engine operating condition, disturbance may occur in the control due to disturbance, and the controllability of ISC feedback may deteriorate. Therefore, the ISC feedback may be temporarily stopped depending on the engine operation status. For example, in the control apparatus for an internal combustion engine described in Patent Document 2, at the time of downshifting, the engine load rapidly decreases, and as a result, the deviation between the actual idle speed and the target idle speed rapidly increases, and the ISC Since feedback controllability deteriorates, ISC feedback is temporarily stopped in response to detection of a downshift.

JP 09-324684 A Japanese Patent Laid-Open No. 02-070955

  By the way, the ignition timing is limited in the settable range due to constraints such as misfire and torque generation efficiency. Due to such ignition timing limitation, the ISC required torque may not be realized. The idle rotation speed also rises and falls due to an implementation error of the ISC required torque in such a case. Then, if the change in the idle rotation speed at this time is reflected in the ISC feedback as it is, the absolute value of the feedback correction term, particularly the absolute value of the feedback integral term may be inappropriately increased or decreased, Controllability deteriorates.

  Such deterioration in controllability due to an error in realizing the ISC required torque can be avoided by prohibiting ISC feedback, for example, in an engine operation region where there is a possibility that an error in realizing the ISC required torque will occur. However, in such a case, the execution area of ISC feedback is limited, and engine stall is likely to occur outside the execution area.

  The deterioration of the controllability can also be avoided by reducing the feedback gain of the ISC feedback in advance so that the effect of the realization error of the ISC required torque is hardly reflected in the ISC feedback. However, in such a case, the response of the actual idle rotation speed to the target idle rotation speed is lowered, and engine stall is likely to occur.

  The present invention has been made in view of such circumstances, and a problem to be solved is to provide a control device for an internal combustion engine that can further improve the resistance to engine stall during idling.

The invention according to claim 1 as a control device for an internal combustion engine that performs feedback control of the idle rotation speed of the internal combustion engine so as to achieve the target idle rotation speed, the invention according to claim 1, in order to solve the above-mentioned problem, the required ignition timing of the idle rotation speed control When the final ignition timing does not coincide with the final ignition timing, the feedback control of the idle rotation speed is stopped.

  In the above configuration, the required ignition timing (ISC required ignition timing) of the idle rotation speed control, which is the ignition timing at which the engine torque (ISC required torque) necessary for obtaining the target idle speed is obtained, is actually set as the ignition timing. It is determined whether or not it coincides with the final ignition timing. According to the mismatch or coincidence of the ISC required ignition timing and the final ignition timing, it is possible to accurately determine whether or not an ISC required torque realization error has occurred.

In the above configuration, the ISC feedback is stopped when it is determined that the ISC required ignition timing and the final ignition timing do not coincide with each other and an ISC required torque realization error has occurred . If the followability of the idle rotation speed to the target idle rotation speed is reduced in this way, the reflection of the change in the idle rotation speed due to the realization error of the ISC required torque can be suppressed to the ISC feedback.

In such a configuration, the ISC feedback is stopped only when an error in realizing the ISC required torque actually occurs. Therefore, in other situations, the ISC feedback can be performed without any restriction. Therefore, in the above configuration, the ISC feedback execution area can be expanded as much as possible, and the feedback gain when there is no error in realizing the ISC required torque can be increased. Therefore, according to the above configuration, the engine stall resistance during idling can be further increased.

Further, in order to solve the above-mentioned problem, the invention according to claim 2 as a control device for an internal combustion engine that performs feedback control of the idle rotation speed of the internal combustion engine so as to achieve the target idle rotation speed is an ISC request for idle rotation speed control. When the torque and the actual torque do not match, the feedback control of the idle rotation speed is stopped.

In the above configuration, since the ISC required torque required for obtaining the idle rotation speed and the actual torque do not match, an implementation error of the ISC required torque is determined. When an ISC request torque implementation error occurs, ISC feedback is stopped . If the ISC feedback is stopped in this way, the reflection of the idle rotation speed change due to the realization error of the ISC required torque to the ISC feedback can be suppressed.

In such a configuration, since the ISC feedback is stopped only when an actual error of the ISC required torque actually occurs, in other situations, the ISC feedback can be performed without being restricted. Therefore, in the above configuration, the ISC feedback execution area can be expanded as much as possible, and the feedback gain when there is no error in realizing the ISC required torque can be increased. Therefore, according to the above configuration, the engine stall resistance during idling can be further increased.

When ISC feedback is performed by integral control such as PI control or PID control, the absolute value of the feedback integral term is undesirably large if a change in idle rotation speed due to an ISC required torque realization error is reflected in the feedback. As a result, the controllability is adversely affected. Therefore, the control apparatus for an internal combustion engine of the present invention as described above is particularly suitable for application to an apparatus for performing ISC feedback by integral control as in claim 3 .

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 of the ISC feedback routine applied to the same embodiment. The flowchart of the ISC feedback routine applied to 2nd Embodiment of this invention. The flowchart of the ISC feedback 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.

  As shown in FIG. 1, in an intake passage 1 of an internal combustion engine to which the control device of the present embodiment is applied, an air cleaner 2 for purifying intake air, an air flow meter 3 for detecting intake air amount, A throttle valve 5 for adjusting the amount of intake air is provided. The throttle valve 5 is driven by a throttle motor 4 and its opening is detected by a throttle sensor 6. The intake passage 1 is connected downstream of the throttle valve 5 to the combustion chamber 8 via an intake port 7 in which an injector 9 for injecting fuel is disposed.

A spark plug 10 for igniting a mixture of air and fuel is installed in the combustion chamber 8 of the internal combustion engine. The combustion chamber 8 is connected to the exhaust passage 12 via the exhaust port 11.
The exhaust passage 12 is provided with an air-fuel ratio sensor 13 for detecting the air-fuel ratio of the air-fuel mixture burned from the oxygen concentration of the exhaust gas flowing through the exhaust passage 12, and a catalytic converter 14 for purifying the exhaust gas.

  The internal combustion engine configured as described above is controlled by the electronic control unit 15. The electronic control unit 15 includes a central processing unit (CPU) that performs various arithmetic processes related to engine control, a read-only memory (ROM) that stores engine control programs and data, CPU calculation results, and sensor detection results. Etc., a random access memory (RAM) for temporarily storing the data. In addition to the air flow meter 3, the throttle sensor 6 and the air-fuel ratio sensor 13, detection signals from various sensors such as a crank angle sensor 16 for detecting the crank angle of the internal combustion engine are input to the electronic control unit 15. The electronic control unit 15 performs engine control by outputting command signals to drive circuits of various actuators such as the throttle motor 4, the injector 9, and the spark plug 10 based on the detection results of these sensors.

  The electronic control unit 15 performs feedback control of idle rotation speed, that is, ISC feedback as part of engine control. This ISC feedback is performed by feedback adjusting the opening of the throttle valve 5 in accordance with the deviation between the target idle speed and the actual idle speed. In this embodiment, such ISC feedback is performed by integral control such as PI control or PID control.

  On the other hand, at the time of ISC feedback, an engine torque (ISC required torque) from which the target idle speed can be obtained is calculated from the target idle speed, and the ignition timing is adjusted so that the ISC required torque can be obtained. It has become. The ignition timing at this time is set by calculating the ignition timing (ISC required ignition timing) at which the ISC required torque is obtained based on the engine speed and the engine load.

  However, if the ignition timing is retarded beyond a certain time, misfire due to poor ignition occurs. Accordingly, the ignition timing is retarded so that the ignition timing is not retarded to the misfire occurrence region.

  Further, when the ignition timing is advanced beyond the MBT (Minimum Advance for Best Torque) point, the generation efficiency of the engine torque is lowered. Therefore, an advance angle guard is performed at the ignition timing so as not to be advanced beyond the MBT point.

  Further, advance / retard angle guard is performed on the ignition timing so that an inappropriate value is not set for the ignition timing due to garbled ROM data. Further, at the time of a failure, in order to limit the control range of the ignition timing, an advance / retard angle guard of the ignition timing may be performed.

  Therefore, the ignition timing that is actually set, that is, the final ignition timing is obtained by performing the various guard processes as described above on the ISC required ignition timing. Therefore, when the guard is applied, the ISC required ignition timing and the final ignition timing may not coincide with each other. In such a case, the ISC required torque cannot be realized.

  Depending on the realization error of the ISC required torque, the idling rotation speed increases and decreases. For example, if the actual torque is higher than the ISC required torque, the idle rotation speed increases. Further, if the actual torque is lower than the ISC required torque, the idling rotational speed will decrease. If the change in the idle rotation speed due to the realization error of the ISC required torque is reflected in the ISC feedback, the absolute value of the feedback correction term, in particular, the absolute value of the feedback integral term is improperly increased. Feedback controllability deteriorates. As a result, the engine rotation speed tends to increase.

  Therefore, in this embodiment, engine stall resistance is ensured by performing ISC feedback in the following manner. That is, in the present embodiment, the presence / absence of an error in realizing the ISC required torque is determined from the mismatch between the ISC required ignition timing and the final ignition timing. When a mismatch between the ISC required ignition timing and the final ignition timing occurs, reducing the feedback gain of the ISC feedback reduces the effect on the ISC feedback of changes in the idle rotation speed caused by the error in realizing the ISC required torque. Like to do.

  FIG. 2 shows a processing procedure of an ISC feedback routine applied to the present embodiment. This routine is repeatedly executed by the electronic control unit 15 at regular control intervals during idling operation of the internal combustion engine.

  When this routine is started, first, in step S100, the ISC required ignition timing is calculated from the current engine speed and engine load. The ISC required ignition timing at this time is calculated as an ignition timing necessary for realizing the ISC required torque obtained from the target idle target rotational speed.

  In subsequent step S101, the various ignition processes as described above are performed on the ISC required ignition timing to calculate the final ignition timing. In step S102, it is determined whether or not the ISC required ignition timing and the final ignition timing are inconsistent.

  Here, if the ISC required ignition timing matches the final ignition timing (S102: NO), it is determined that no error in realizing the ISC required torque has occurred, and the ISC feedback with the feedback gain set to a normal value. Is executed (S103).

  On the other hand, if the ISC required ignition timing does not match the final ignition timing (S102: YES), the feedback gain is set to a value smaller than the normal value, assuming that an ISC required torque realization error has occurred. ISC feedback is executed (S104).

According to the control apparatus for an internal combustion engine of the present embodiment as described above, the following effects can be obtained.
(1) In this embodiment, when the ISC required ignition timing does not coincide with the final ignition timing, that is, when an actual error of the ISC required torque actually occurs, the feedback gain of the ISC feedback is reduced. As a result, the deterioration of the controllability of ISC feedback due to the error in realizing the ISC required torque is suppressed. Therefore, ISC feedback can be performed even in an engine operation region where there is a probability of occurrence of an ISC required torque realization error, and the execution region of ISC feedback is expanded. As long as an error in realizing the ISC required torque has not occurred, ISC feedback can be performed by increasing the feedback gain. Therefore, according to the present embodiment, it is possible to increase engine stall resistance during idling while avoiding deterioration of controllability due to an error in realizing the ISC required torque.

  (2) In this embodiment, an implementation error of the ISC required torque is confirmed based on a mismatch between the ISC required ignition timing and the final ignition timing. For this reason, it is possible to easily and accurately confirm the error in realizing the ISC required torque.

(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 the first embodiment, when an error in realizing the ISC required torque occurs, the ISC feedback feedback gain is decreased, so that the followability of the idle rotational speed to the target idle rotational speed is reduced, thereby reducing the ISC feedback. The control mode was changed. On the other hand, in the present embodiment, ISC feedback is stopped when an implementation error of the ISC request torque that deteriorates the controllability of ISC feedback occurs.

  FIG. 3 shows the processing procedure of the ISC feedback routine applied to this embodiment. This routine is repeatedly executed by the electronic control unit 15 at regular control intervals during idling operation of the internal combustion engine.

  When this routine is started, first, in step S200, the ISC required ignition timing is calculated from the current engine speed and engine load. The ISC required ignition timing at this time is calculated as an ignition timing necessary for realizing the ISC required torque obtained from the target idle target rotational speed.

  In the subsequent step S201, the various ignition processes as described above are performed on the ISC required ignition timing to calculate the final ignition timing. In step S202, it is determined whether the ISC required ignition timing and the final ignition timing do not match.

  Here, if the ISC required ignition timing coincides with the final ignition timing (S202: NO), ISC feedback is executed (S203), assuming that an error in realizing the ISC required torque has not occurred.

  On the other hand, if the ISC required ignition timing and the final ignition timing do not match (S202: YES), it is determined that an ISC required torque realization error has occurred, and the execution of ISC feedback is stopped (S204).

According to the present embodiment as described above, the same effects as (1) and (2) described above or effects equivalent thereto can be obtained.
(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.

  In the first and second embodiments, an implementation error of the ISC required torque is confirmed based on a mismatch between the ISC required ignition timing and the final ignition timing. On the other hand, in the present embodiment, the actual torque of the internal combustion engine is obtained, and the realization error of the ISC required torque is confirmed by the mismatch between the actual torque and the ISC required torque.

  In the present embodiment, the actual torque is obtained in the following manner. First, the MBT point torque in the current engine operating condition is calculated from the current engine speed and engine load. Next, torque generation efficiency is calculated from the ignition timing. Then, the actual torque is obtained by integrating the calculated MBT point torque and the torque generation efficiency.

  FIG. 4 shows a processing procedure of an ISC feedback routine applied to the present embodiment. This routine is repeatedly executed by the electronic control unit 15 at regular control intervals during idling operation of the internal combustion engine.

  When this routine is started, first, in step S300, the ISC required torque is calculated from the target idle rotation speed. The ISC required torque at this time is calculated as the engine torque necessary for realizing the target idle target rotational speed.

  In the subsequent step S301, the actual torque is obtained in the manner described above. In step S302, it is determined whether or not the ISC required torque and the actual torque do not match.

  Here, if the ISC request torque and the actual torque match (S302: NO), it is determined that no error has occurred in the ISC request torque, and ISC feedback is executed with the feedback gain set to a normal value. (S303).

  On the other hand, if the ISC required torque and the actual torque do not match (S302: YES), it is determined that an error in realizing the ISC required torque has occurred, and the ISC feedback with the feedback gain set to a value smaller than the normal value. Or the execution of ISC feedback is stopped (S304).

According to the present embodiment as described above, an effect similar to or equivalent to the above (1) can be achieved.
The above-described embodiments can be implemented with the following modifications.

  In the above embodiment, ISC feedback is performed by integral control. However, ISC feedback may be performed by control other than integral control, such as PD control. Even in such a case, the controllability of the ISC feedback deteriorates due to an error in realizing the ISC required torque. Therefore, if the feedback gain of the ISC feedback is reduced or the ISC feedback is stopped at the time of the ISC request torque realization error in the above mode, the deterioration of the controllability due to the ISC request torque realization error is avoided, but the idle Engine stall resistance during operation can be increased.

  In the above embodiment, the deterioration of controllability due to the realization error of the ISC required torque is avoided by reducing the feedback gain of the ISC feedback or stopping the ISC feedback. Of course, if the control mode of the ISC feedback is changed so that the followability of the idle rotational speed to the target idle rotational speed is reduced at the time of an implementation error of the ISC required torque, it is caused by an implementation error of the ISC required torque. It is possible to avoid deterioration of controllability.

  DESCRIPTION OF SYMBOLS 1 ... Intake passage, 2 ... Air cleaner, 3 ... Air flow meter, 4 ... Throttle motor, 5 ... Throttle valve, 6 ... Throttle sensor, 7 ... Intake port, 8 ... Combustion chamber, 9 ... Injector, 10 ... Spark plug, 11 DESCRIPTION OF SYMBOLS ... Exhaust port, 12 ... Exhaust passage, 13 ... Air-fuel ratio sensor, 14 ... Catalytic converter, 15 ... Electronic control unit, 16 ... Crank angle sensor

Claims (3)

In the control device for an internal combustion engine that performs feedback control of the idle rotation speed of the internal combustion engine so as to become the target idle rotation speed,
The control apparatus for an internal combustion engine, wherein when the required ignition timing of the idle rotational speed control and the final ignition timing do not coincide with each other, the idle rotational speed feedback control is stopped. In the control device for an internal combustion engine that performs feedback control of the idle rotation speed of the internal combustion engine so as to become the target idle rotation speed,
The control apparatus for an internal combustion engine, wherein when the required torque for the idle rotation speed control does not match the actual torque, the feedback control for the idle rotation speed is stopped. The feedback control, the control device for an internal combustion engine according to claim 1 or 2 is performed by integral control.

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