JP2012017679A - Internal combustion engine control apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an internal combustion engine control apparatus that can satisfactorily control intake flow rate characteristics through throttle opening adjustment while avoiding excessive correction even during learning transient time.SOLUTION: The internal combustion engine control apparatus performs learning of an intake flow rate change ratio for each opening region TA(1)-TA(7) sectioned depending on the throttle opening, and uses a value of the learning values of the flow rate characteristics in the opening region of a side with opening higher than the opening region as a tentative value of the learning value in an opening region where the learning of the flow rate change ratio is not completed.

Description

  The present invention relates to a control device for an internal combustion engine that learns a flow rate characteristic of air flowing through a throttle valve for each opening range divided according to the throttle opening.

  The flow rate of the intake air detected by the air flow meter at a predetermined throttle opening of the internal combustion engine varies depending on individual differences in sensor detection characteristics, deposits on the throttle valve, and the like. Therefore, the intake flow rate control accuracy is improved by learning, as the learning value, the flow rate change rate of the intake air passing through the throttle valve for each opening region divided according to the throttle opening.

  The greater the number of opening regions in which learning is performed, the more precise control is possible. However, as the number of opening regions for learning increases, it takes time to complete learning in all the opening regions, and until that is completed, leaving unopened opening regions, Control will have to be done.

  Conventionally, Patent Document 1 discloses a control device for an internal combustion engine that learns, as a learning value, a deviation in fuel injection amount required to make the air-fuel ratio the stoichiometric air-fuel ratio for each flow rate region divided according to the intake flow rate. ing. In the control apparatus for an internal combustion engine described in this document, the above learning is performed mainly to compensate for the deviation of the fuel injection amount accompanying the deterioration of the sensor that detects the intake flow rate. In this control device, the range of the flow rate region in which learning is performed is limited, and control is performed without learning in the flow rate region outside the range. Therefore, in the control device of the same document, in a flow rate region out of the learning range, a learning correction coefficient is set by interpolation using learning values of two flow rate regions selected from the learned flow rate region. .

  For example, as shown in FIG. 5, when learning values KL0 to KLn are learned in each flow rate region of P0 to Pn, a range from “P0” to “Pn” is a learning range. Here, in the control device of the above document, in the flow rate region A outside the minimum side of the learning range, two learning values KL0 and KL1 of the lower flow rate region P0 and the next flow rate region P1 are used. The learning correction coefficient KLA for the flow area A is set by interpolation. Further, in the flow rate region B outside the maximum range of the learning range, the flow rate region B is obtained by interpolation using the two learning values KLn and KLn−1 of the upper flow rate region Pn and the next flow rate region Pn−1. The learning correction coefficient KLB is set.

Japanese Patent Laid-Open No. 02-259257

  As in the conventional control device for an internal combustion engine, a method for setting a learning correction coefficient in a region where learning has not been performed by interpolation using a learning value in a region where learning has been completed is, under certain conditions, Works effectively. That is, the method of the above document is effective only because a linear relationship is established between the difference in the fuel injection amount accompanying the sensor deterioration and the intake air flow rate at least within the interpolation range.

  On the other hand, the relationship between the deviation of the intake air flow rate attributed to deposit adhesion and the throttle opening is not necessarily linear. For this reason, when the learning value of the unlearned opening area is obtained by interpolation using the learning value of the opening area where learning has been completed, an appropriate value is not necessarily set as the learning value. As a result, overcorrection by an inappropriate learning value may be performed.

  The present invention has been made in view of such circumstances, and the problem to be solved is to suitably control the intake flow rate characteristic through throttle opening adjustment while avoiding overcorrection even during a learning transition. An object of the present invention is to provide an internal combustion engine control device.

  In order to solve the above-mentioned problem, the invention according to claim 1 as a control device for an internal combustion engine that learns the flow rate characteristic of intake air that passes through the throttle valve for each opening range divided according to the throttle opening amount The learning value of the flow rate characteristic in the opening area higher than the opening area is used as the temporary learning value in the opening area where the characteristic is not learned.

  The deviation of the intake flow rate characteristic due to deposit adhesion tends to increase as the throttle opening decreases. For this reason, it is estimated that the difference in intake flow rate characteristics in a certain opening range is larger than the shift in intake flow characteristics in the opening range higher than the opening range. Therefore, if the learning value of the flow rate characteristic in the opening range higher than the opening range is used as the temporary learning value in the opening range in which the learning of the flow rate characteristic is not completed, Thus, it is possible to avoid overestimating the deviation of the flow rate characteristic in the opening range. Therefore, according to the above configuration, the intake flow rate characteristic can be suitably controlled through the throttle opening adjustment while avoiding overcorrection even during a learning transition.

  The setting of such a provisional learning value is, as described in claim 2, when learning of the flow rate characteristic is completed in a certain opening region, until the flow rate characteristic corresponds to another learned opening region. It is possible to sequentially set the learning value of the opening region, which has been learned while moving the opening region to the low opening side, to the temporary learning value.

  Further, according to claim 3, when there is no opening region whose flow rate characteristic has already been learned on the high opening side of the unlearned opening region, an initial value of the flow characteristic in the predetermined opening region is temporarily set. It is desirable to use it as a learning value.

Note that the rate of change of the actual intake air flow rate with respect to the reference value of the intake air flow rate in the corresponding opening range can be used as the intake air flow rate characteristic for learning.
Incidentally, the control apparatus for an internal combustion engine according to the present invention implements torque demand control for adjusting the throttle opening so as to obtain the intake air flow rate necessary for setting the engine torque as the target torque. Therefore, it is suitable for application to a control device.

BRIEF DESCRIPTION OF THE DRAWINGS Schematic which shows typically the whole structure of one Embodiment of this invention. The graph which shows the relationship between the throttle opening in the same embodiment, the tolerance upper limit value of a flow rate change rate, and a tolerance lower limit value. The graph which shows the setting aspect of the temporary learning value in the same embodiment. The flowchart which shows the process sequence of the temporary learning value setting routine employ | adopted as the same embodiment. The graph which shows the setting aspect of the learning correction coefficient in the control apparatus of the conventional internal combustion engine.

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.
FIG. 1 shows the overall configuration of the present embodiment. As shown in the figure, the internal combustion engine to which the control device of the present embodiment is applied includes an intake passage 1, a combustion chamber 2, and an exhaust passage 3. The intake passage 1 of the internal combustion engine is provided with an air flow meter 4 for detecting the intake flow rate and a throttle valve 6 that is driven by a throttle motor 5 to adjust the intake flow rate. The throttle motor 5 incorporates a throttle sensor 7 that detects the opening of the throttle valve 6 (throttle opening).

  Such an internal combustion engine is controlled by an electronic control unit 8. The electronic control unit 8 includes a central processing unit (CPU), a read only memory (ROM), a random access memory (RAM), and an input / output port (I / O). Here, the CPU performs various arithmetic processes for engine control, and the ROM stores a program and data for engine control. The RAM temporarily stores the calculation results of the CPU, the detection results of the sensors, and the like, and the I / O functions as an interface that mediates exchange of signals with the outside.

  Detection signals from various sensors for detecting engine operating conditions, including the air flow meter 4 and the throttle sensor 7, are input to the input port of the electronic control unit 8. The actuator control circuit including the throttle motor 5 is connected to the output port of the electronic control unit 8.

  Now, in the internal combustion engine configured as described above, torque demand control is executed as part of engine control. Torque demand control sets the target torque at a certain point in the future and sets the throttle opening in advance by taking into account the response delay of the intake air so that the intake air flow required to make the engine torque the target torque can be obtained. It is a control to adjust.

  In order to execute such torque demand control, it is necessary to accurately grasp the intake flow rate for each throttle opening. However, the flow rate characteristic of intake air at a predetermined throttle opening varies depending on variations in the output characteristics of the throttle sensor 7 and the state of deposit adhesion to the throttle valve 6. Therefore, in the present embodiment, the flow rate characteristic of the intake air passing through the throttle valve 6 is learned for each opening range divided according to the throttle opening. More specifically, in this embodiment, the flow rate change rate in each opening degree region is learned. The flow rate change rate here indicates the ratio of the actual intake flow rate to the reference value of the intake flow rate in the corresponding opening degree region.

  Note that a long time is required to learn the flow rate change rate in all opening regions. For this reason, during the learning transition, it is necessary to perform torque demand control while leaving an opening region in which the flow rate change rate has not been learned. Therefore, in the present embodiment, a torque value control is performed by setting a temporary learning value in the unlearned opening degree region.

  FIG. 2 shows the relationship between the throttle opening and the tolerance upper limit value and the tolerance lower limit value of the flow rate change rate. Note that the tolerance lower limit value in the figure is set to a value that takes into account when the reduction of the intake air flow rate due to deposit adhesion reaches an assumed maximum value in addition to the tolerances of the detection system and the intake air adjustment system.

  Here, the difference in the intake flow rate characteristic is greatly influenced by the deposit attached to the throttle valve 6 more than the variation in the output characteristic of the throttle sensor 7. The deviation of the flow characteristics due to the deposit tends to increase as the throttle opening decreases.

  In the present embodiment, in view of the above tendency, the provisional learning value is set in the following manner. In other words, in the present embodiment, the learning value value of the flow rate change rate in the opening region higher than the opening region is used as the temporary learning value value in the unlearned opening region. I have to. Further, in this embodiment, when learning of the flow rate change rate is completed in a certain opening region, the learning is performed while moving the opening region to the low opening side until the flow rate change rate reaches another learned opening region. The learning value value of the opening region that has been completed is sequentially set to the provisional learning value value. Furthermore, in the present embodiment, when there is no opening degree region where learning has been completed on the high opening side of the unlearned opening degree region, the initial value of the flow rate change rate in the corresponding opening degree region (here, “1” .0 ") are used as temporary learning values.

  FIG. 3 shows a setting mode of temporary learning values in the present embodiment. This figure shows a state immediately after the learning of the flow rate change rate in the opening area TA (5) is completed. In the case of the figure, when learning of the opening area TA (5) is completed, whether or not the opening area TA (4) on the lower opening side than the opening area TA (5) has been learned. Is confirmed. In the case of the figure, since the flow rate change rate is not learned in the opening area TA (4), the learning value (flow rate change rate) of the opening area TA (5) is the temporary value of the opening area TA (4). The learning value is set (copied). Subsequently, it is confirmed whether or not the opening area TA (3) on the lower opening side has been learned. Since this opening degree area TA (3) has not yet learned the flow rate change rate, the learning value of the opening degree area TA (5) is similarly set to the provisional learning value of the opening degree area TA (3). (Copied).

  Next, it is confirmed whether or not the opening area TA (2) on the lower opening side has been learned. In the case of the figure, since the opening degree area TA (2) has been learned, the learning value of the opening degree area TA (5) is not copied to the opening degree area TA (2).

  Note that the opening area TA (1) in the figure is not yet learned, but when the learning of the opening area TA (2) on the higher opening side is completed, the opening area TA (2) ) Learning value is set as a provisional learning value of the opening degree area TA (1).

  On the other hand, the opening regions TA (6) and TA (7) are unlearned, but there is no learned opening region on the higher opening side than the opening regions TA (6) and TA (7). In TA (7), the initial value (1.0) is used as the flow rate change rate.

  FIG. 4 shows a flowchart of the provisional learning value setting routine employed in this embodiment. The processing of this routine is read from the ROM each time processing related to learning of the flow rate change rate is completed, and is executed by the CPU of the electronic control unit 8.

  When this routine is started, first, in step S100, it is determined whether or not the flow rate change rate in any opening region has been learned in the previous learning process. If it is determined that it is not immediately after the completion of learning (S100: NO), the process of this routine is terminated as it is. If not (S100: YES), the process proceeds to step S101. In the following description, it is assumed that learning of the opening area TA (k) (“k” is the opening area number) has been completed.

When the process proceeds to step S101, the value of the number k is set to the variable i, and in the subsequent step S102, the value of the variable i is subtracted by “1”.
In the next step S103, it is determined whether or not the flow rate change rate in the opening region TA (i) has been learned. If it has been learned (S103: YES), the processing of this routine is terminated. .

  On the other hand, if the opening area TA (i) is not learned (S103: NO), the process proceeds to step S104. In step S104, the learning value of the flow rate change rate of the opening area TA (k). Is set to the value of the provisional learning value in the opening area TA (i). Thereafter, the processes in steps S102 to S104 are repeated until the learned opening degree region is reached.

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, learning of the flow rate change rate of the intake air is performed for each opening region divided according to the throttle opening, and the temporary learning value in the opening region where the flow rate change rate is not learned is obtained. As the value, the learning value of the flow rate characteristic in the opening region on the higher opening side than the opening region is used. Further, in this embodiment, when learning of the flow rate change rate is completed in a certain opening region, the learning is performed while moving the opening region to the low opening side until the flow rate change rate reaches another learned opening region. The learning value value of the opening region that has been completed is sequentially set to the provisional learning value value. Furthermore, in the present embodiment, when there is no learned opening area on the high opening side of the unlearned opening area, the initial value (1.0) of the flow rate change rate in the corresponding opening area is set in advance. It is used as a temporary learning value.

  The deviation in the flow rate characteristic of the intake air due to deposit adhesion tends to increase as the throttle opening decreases. For this reason, it is estimated that the difference in intake flow rate characteristics in a certain opening range is larger than the shift in intake flow characteristics in the opening range higher than the opening range. For this reason, the learning rate value of the flow rate change rate in the opening region higher than the opening region is used as the temporary learning value value in the unlearned opening region. For example, it is possible to avoid overestimating the deviation of the flow rate characteristic in the opening range. Therefore, according to the present embodiment, it is possible to suitably control the intake flow rate characteristic through the throttle opening adjustment while avoiding overcorrection even during a learning transition.

  (2) In the present embodiment, in the control device that performs torque demand control for adjusting the throttle opening so as to obtain the intake air flow rate necessary for setting the engine torque as the target torque, the above unlearned The provisional learning value is set in the opening range. For this reason, even during learning transition, the realization accuracy of the target intake air flow rate and thus the realization accuracy of the target torque are improved, and deterioration of drivability due to unlearning is suppressed.

In addition, the said embodiment can also be changed and implemented as follows.
In the above embodiment, the initial value of the flow rate change rate in each opening region is set to “1.0”, but the initial value setting mode is not limited to this and may be changed as appropriate. For example, it may be possible to change the initial value for each opening region.

  In the above embodiment, the case where the control device of the present invention is applied to an internal combustion engine that performs torque demand control has been described. However, the present invention is also applicable to an internal combustion engine that does not perform torque demand control. In any case, if the value of the provisional learning value is set as in the above embodiment, the control accuracy of the intake flow rate is improved while avoiding over-correction by overestimating the deviation of the intake flow rate characteristic. Will be able to.

  In the above embodiment, the case of learning the flow rate change rate of the intake air has been explained. However, for example, when learning of other flow rate characteristic values such as the flow velocity of the intake air when passing through the throttle valve 6 is learned. The present invention is applicable.

  In the above embodiment, when learning of the flow characteristics is completed in a certain opening area, the learning is completed while moving the opening area to the low opening side until it reaches another opening area where the flow characteristics have been learned. The learning value of the opening range was set to the temporary learning value in order, but the number of opening regions for setting the temporary learning value was limited to a certain number or less. Anyway.

  -In the above embodiment, immediately after learning of the flow characteristics in a specific opening region is completed, the provisional learning value of the opening region on the lower opening side is set. The timing for setting the provisional learning value is not limited to this, and may be arbitrarily changed. For example, when the throttle opening enters an unlearned opening range, a provisional learning value for the opening range may be set.

  DESCRIPTION OF SYMBOLS 1 ... Intake passage, 2 ... Combustion chamber, 3 ... Exhaust passage, 4 ... Air flow meter, 5 ... Throttle motor, 6 ... Throttle valve, 7 ... Throttle sensor, 8 ... Electronic control unit

Claims (5)

In the control device for an internal combustion engine that learns the flow rate characteristic of the intake air that passes through the throttle valve for each opening region divided according to the throttle opening,
The learning value of the flow rate characteristic in the opening range higher than the opening range is used as a temporary learning value in the opening range where the flow rate characteristic is not learned. Control device for internal combustion engine. When learning of the flow rate characteristic is completed in a certain opening region, the learning of the opening region that has completed the learning while moving the opening region to the low opening side until it corresponds to another opening region where the flow characteristic has been learned. The control device for an internal combustion engine according to claim 1, wherein the learning value is sequentially set to a temporary learning value. When there is no opening area in which the flow characteristics have been learned on the high opening side of the unlearned opening area, the initial value of the flow characteristics in the predetermined opening area is used as a temporary learning value. Item 3. The control device for an internal combustion engine according to Item 1 or 2. The control device for an internal combustion engine according to any one of claims 1 to 3, wherein the flow rate characteristic is a change rate of an actual intake flow rate with respect to a reference value of the intake flow rate in a corresponding opening degree region. The internal combustion engine according to any one of claims 1 to 4, wherein the control device performs torque demand control for adjusting a throttle opening so that an intake air flow rate necessary for setting the engine torque as a target torque is obtained. Engine control device.

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