JP2018028272A - Control device for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control device for an internal combustion engine that can suppress deterioration of drivability while suppressing an increase of processing load, and that facilitates addition of limitation to an upper limit on intake air amount based on a new factor.SOLUTION: A control device for an internal combustion engine comprises: a storage unit in which factors and necessity of execution of gradual change processing for releasing a limit of an intake air amount with upper limit values by continuously increasing the upper limit values when the factors are eliminated are stored in association with each other for each kind of a plurality of factors; a limiting unit for, when a plurality of factors have occurred, selecting a minimum upper limit value out of a plurality of upper limit values corresponding to the occurring factors and limiting the intake air amount on the basis of the selected upper limit value; a determination unit for determining the necessity of execution of gradual change processing to the selected upper limit value by referring to the storage unit; and a gradual changing unit for performing the gradual change processing to the selected upper limit value when execution of the gradual change processing to the selected upper limit value is determined to be necessary, and if the factor corresponding to the selected upper limit value has been eliminated.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a control device for an internal combustion engine.

  In Patent Document 1, in order to suppress a torque shock due to an increase in torque at the time of return from the fuel cut, the torque at the time of return from the fuel cut is the minimum of torque requests required based on various viewpoints. Techniques for limiting to values are disclosed. Such torque limitation of the internal combustion engine is performed by limiting the intake air amount, and the control of the intake air amount is performed by the control device of the internal combustion engine.

JP 2009-162185 A

  When a predetermined factor occurs, the upper limit value of the intake air amount may be limited from various viewpoints. When such a factor is eliminated, the restriction on the intake air amount is released. Here, if the restriction on the intake air amount is suddenly released, depending on the type of the factor, a torque shock or the like may occur and drivability may deteriorate. For this reason, when the factor is eliminated and the restriction on the intake air amount is released, it is conceivable to execute a change-over process for gradually increasing the upper limit value depending on the type of the factor. By gradually increasing the upper limit value of the intake air amount and releasing the restriction, it is possible to suppress deterioration in drivability.

  A plurality of factors that limit the intake air amount as described above are determined in advance, and the necessity of executing the change-over process is also determined in advance for each factor. Here, when a plurality of factors occur, it is conceivable to limit the intake air amount with a minimum value among a plurality of upper limit values respectively corresponding to the plurality of factors.

  It is possible that multiple factors are resolved simultaneously. In this case, the change-over process is executed for all of the plurality of upper limit values respectively corresponding to the plurality of factors, and the plurality of upper limit values that increase during the change-over process are compared, and the intake air amount is determined by the minimum upper limit value. It is possible to restrict. However, in this case, the processing load of the control device for the internal combustion engine increases.

  In addition, as described above, the control device that compares a plurality of upper limit values during the change process and limits the intake air amount by the minimum upper limit value is added and improved based on a new factor. Is also possible. In this case, it is necessary to improve the control device so that the upper limit value corresponding to the new factor can be compared with the upper limit value in the other change process while performing the change process, and a new limit is added. Can be difficult.

  Therefore, an object of the present invention is to provide a control device for an internal combustion engine that can suppress deterioration in drivability while suppressing an increase in processing load and that can easily add an upper limit on the intake air amount based on a new factor. To do.

  An object of the present invention is to provide a control device for an internal combustion engine that limits the upper limit of the intake air amount of the internal combustion engine to an upper limit value corresponding to the factor when a predetermined factor occurs. The necessity of executing the change-over process for releasing the restriction of the intake air amount by the upper limit value by gradually increasing the upper limit value continuously or stepwise when it is eliminated is a plurality of types of the factors When a plurality of the factors are generated and a storage unit stored in association with each other, a minimum upper limit value is selected from among the plurality of upper limit values corresponding to each of the generated plurality of factors. And determining with reference to the limiting unit that limits the intake air amount based on the selected upper limit value and the storage unit, whether the execution of the change process for the selected upper limit value is necessary. Part and before the selected upper limit When it is determined that execution of removal / change processing is necessary and the factor corresponding to the selected upper limit is resolved, the removal / execution that executes the removal / change processing on the selected upper limit is performed. This can be achieved by a control device for an internal combustion engine provided with a transformation section.

  According to the above configuration, when a plurality of factors are eliminated at the same time and the restriction on the intake air amount is released, only the minimum upper limit value among the plurality of upper limit values corresponding to each of the plurality of factors is changed. Is executed. Therefore, the processing load is compared with the case where the change processing is performed on all of the plurality of upper limit values and the intake air intake amount is limited by the minimum upper limit value among the plurality of upper limit values during the change processing. Can be suppressed. For this reason, deterioration of drivability can be suppressed while suppressing an increase in processing load. In addition, according to the above configuration, even when a plurality of factors are eliminated at the same time, a change process is performed on all of the corresponding upper limit values to compare a plurality of upper limit values during the change process. There is no need to do. For this reason, it is also easy to add a restriction based on a new factor to the control device.

  According to the present invention, it is possible to provide a control device for an internal combustion engine that can suppress deterioration in drivability while suppressing an increase in processing load and that can easily add an upper limit on the intake air amount based on a new factor.

FIG. 1 is a schematic configuration diagram of an engine system. 2A to 2D are timing charts illustrating the release of the upper limit of the intake air amount based on each of a plurality of factors. FIG. 3 is a timing chart illustrating the release of the upper limit of the intake air amount when both of the two factors are eliminated simultaneously. FIG. 4 is a flowchart showing an example of intake air amount upper limit control executed by the ECU. FIG. 5 shows an example of a table stored in the ROM of the ECU. FIG. 6 is a timing chart illustrating the upper limit value that is increased by the modification process of the modification.

  FIG. 1 is a schematic configuration diagram of an engine system 1. As shown in FIG. 1, the engine system 1 includes an ECU (Electronic Control Unit) 50 that controls the engine 20. The ECU 50 is an example of a control device for an internal combustion engine. The engine 20 is an example of an internal combustion engine that burns an air-fuel mixture in a combustion chamber 23 in a cylinder block 21 and reciprocates a piston 24. The engine 20 is an in-line four-cylinder gasoline engine, but is not limited to this as long as it has a plurality of cylinders, and may be a diesel engine, for example.

  The cylinder head of the engine 20 is provided with an intake valve Vi that opens and closes an intake port and an exhaust valve Ve that opens and closes an exhaust port for each cylinder. A spark plug 27 for igniting the air-fuel mixture in the combustion chamber 23 is attached to the top of the cylinder head for each cylinder.

  The intake port of each cylinder is connected to the surge tank 18 via a branch pipe for each cylinder. An intake pipe 10 is connected to the upstream side of the surge tank 18, and an air cleaner 19 is provided at the upstream end of the intake pipe 10. The intake pipe 10 is provided with an air flow meter 15 for detecting the intake air amount and an electronically controlled throttle valve 13 in order from the upstream side.

  In each cylinder, an in-cylinder injection valve 12 that injects fuel into the combustion chamber 23 is installed. The fuel injected from the in-cylinder injection valve 12 is mixed with intake air in the combustion chamber 23 to form an air-fuel mixture, compressed by the piston 24, and ignited and burned by the spark plug 27. The engine 20 is not limited to the one provided with the in-cylinder injection valve 12, and may be an engine having only the port injection valve or an engine having both the in-cylinder injection valve and the port injection valve. Good.

  A knock sensor 29 for detecting knocking of the engine 20 is provided on the side wall surface of the cylinder block of the engine 20. The engine 20 is provided with a crank angle sensor 25 that detects a crank angle.

  The fuel in the fuel tank 37 is supplied by the low pressure pump 38 and the high pressure pump 39 to the in-cylinder injection valve 12 via the fuel pipe and the delivery pipe.

  The exhaust port of each cylinder is connected to the exhaust pipe 30 via a branch pipe for each cylinder. A catalyst 31 is provided in the exhaust pipe 30. An air-fuel ratio sensor 33 for detecting the air-fuel ratio of the exhaust gas is installed on the upstream side of the catalyst 31. The air-fuel ratio sensor 33 is a so-called wide-area air-fuel ratio sensor, which can continuously detect an air-fuel ratio over a relatively wide range and outputs a signal having a value proportional to the air-fuel ratio.

  The ECU 50 includes a central processing unit (CPU), a random access memory (RAM), a read only memory (ROM), and a storage device. The ECU 50 performs various controls by executing a program stored in the ROM or the storage device. The ECU 50 is functionally realized by a CPU, a ROM, a RAM, and the like. Details will be described later.

  In addition to the ignition plug 27, the throttle valve 13 and the cylinder injection valve 12, the knock sensor 29, the air flow meter 15, the air-fuel ratio sensor 33, the crank angle sensor 25, the ECU 50 includes an accelerator opening sensor that detects the accelerator opening. 11 and a water temperature sensor 35 that detects the temperature of cooling water that cools the engine 20 is electrically connected. The spark plug 27, the in-cylinder injection valve 12, and the knock sensor 29 are provided for each cylinder. The ECU 50 controls the ignition plug 27, the throttle valve 13, the in-cylinder injection valve 12 and the like so as to obtain a desired output based on detection values of various sensors and the like, and performs ignition timing, fuel injection amount, fuel injection timing. Control the throttle opening.

  When knocking is detected by the knock sensor 29, the ECU 50 controls the timing of voltage application to the spark plug 27 and retards the ignition timing to suppress the occurrence of knocking. Further, the ECU 50 sets a target value of the intake air amount based on the output from the accelerator opening sensor 11 and the like so that the engine 20 outputs a desired torque. The throttle opening of the throttle valve 13 is controlled so that the intake air amount is controlled to this target value.

  Next, the limitation on the upper limit of the intake air amount by the ECU 50 will be described. When a predetermined factor occurs in the engine 20 and its peripheral devices, the ECU 50 limits the upper limit of the intake air amount to an upper limit value corresponding to the factor from various viewpoints. When the cause is resolved, the upper limit is removed. In this embodiment, a plurality of factors A to D will be described. The upper limits A1 to D1 correspond to the factors A to D, respectively.

  2A to 2D are timing charts illustrating the release of the upper limit of the intake air amount based on each of the plurality of factors A to D. FIG. 2A to 2D, the upper limit of the intake air amount is limited based on each of the factors A to D under the same operating condition where the target value T of the intake air amount is constant, and the factors A to D are the same at the same timing. The case where D is eliminated is illustrated. The magnitude relationship between the upper limit values A1 to D1 is not limited to that shown in FIGS. 2A to 2D.

  For example, as shown in FIG. 2A, when the upper limit of the intake air amount is limited by the upper limit value A1 corresponding to the factor A, the intake air amount even if the target value T of the intake air amount exceeds the upper limit value A1. The amount is limited to the upper limit value A1. When the target value of the intake air amount is less than or equal to the upper limit value A1, the intake air amount is controlled to the target value. First, the factor A will be described.

  Factor A is that at least one of the plurality of cylinders misfires. When unburned fuel flows through the exhaust pipe 30 due to misfire and reacts with oxygen in the exhaust gas on the catalyst 31 and burns, the catalyst 31 may be overheated and melted down. Therefore, when the factor A is generated, from the viewpoint of suppressing the excessive temperature rise of the catalyst 31, the fuel of the misfire cylinder is cut and the upper limit of the intake air amount is limited to the upper limit value A1. The upper limit value A1 is calculated by the ECU 50 based on the engine speed, the target air-fuel ratio in a cylinder in which no misfire has occurred, and the like. The determination of misfire is made by the ECU 50 based on, for example, the rotation fluctuation of the crankshaft or the output value of the in-cylinder pressure sensor.

  If it is determined that no misfire has occurred during the restriction of the intake air amount by the upper limit value A1, the restriction by the upper limit value A1 is released after the change-over process described later, assuming that the factor A has been eliminated. Here, when the factor A is eliminated and the engine 20 returns from misfire, there is a possibility that the torque increases instantaneously and a torque shock occurs. Therefore, immediately after the factor A is eliminated, the upper limit value A1 is lowered by a predetermined intake amount than before. The upper limit value A1 immediately after the factor A is eliminated is the intake air amount at the time when it is determined that the factor A is eliminated × {(total number of cylinders−number of misfiring cylinders) / (total number of cylinders)}. Although it is calculated, it is not limited to this.

  Next, a change-over process for gradually increasing the upper limit value A1 is executed, and the upper limit of the intake air amount by the upper limit value A1 is gradually relaxed. The restriction by the upper limit value A1 is released when the upper limit value A1 during the change-over process is equal to or greater than the maximum intake air amount M that the engine 20 can take.

  Next, the factor B will be described. Factor B is that the target ignition timing is controlled to the retard side in order to suppress the occurrence of knocking. In order to suppress the occurrence of knocking, the target ignition timing is set to be retarded from MBT (Minimum Advance for Best Torque), which is the ignition timing at which the output torque becomes maximum. As the ignition timing is retarded in this manner, the exhaust gas temperature may rise and the catalyst 31 may overheat, and smoke may increase. Therefore, when the factor B is generated, the upper limit of the intake air amount is limited from the viewpoint of suppressing the excessive temperature rise of the catalyst 31 and the increase of smoke. The upper limit value B1 is calculated by the ECU 50 based on the engine speed and ignition timing, and is calculated smaller as the retard amount is larger or the engine speed is larger. The ECU 50 determines whether or not knocking is present based on the output value of the knock sensor 29 as described above.

  If it is determined that knocking has not occurred over a predetermined period while the intake air amount is limited by the upper limit value B1, the target ignition timing is controlled to the advance side and the upper limit value B1 is determined, assuming that the factor B has been eliminated. The restriction on the intake air amount due to is released. Note that, unlike the upper limit value A1, the upper limit value B1 is immediately released from the restriction without being subjected to the change process. The reason why the change process is not executed for the upper limit value B1 is that the upper limit value B1 is higher than the other upper limit values, is close to the maximum value M of the intake air amount that the target value T can take, and is the upper limit value B1. This is because even if the restriction due to is removed immediately, drivability is not greatly affected.

  Next, the factor C will be described. The factor C is a case where the temperature of the engine 20 belongs to a low temperature range below a predetermined temperature. When the temperature of the engine 20 belongs to a low temperature range equal to or lower than a predetermined temperature, the ECU 50 is set so that the target fuel injection amount is increased in order to suppress deterioration of fuel combustibility. For this reason, the target fuel injection amount may be set exceeding the discharge capacity of the high-pressure pump 39. When the factor C is thus generated, the upper limit of the intake air amount is limited from the viewpoint of suppressing the target fuel injection amount from being set exceeding the discharge capacity of the high-pressure pump 39. Thereby, the increase in the target fuel injection amount corresponding to the target air-fuel ratio is suppressed. The upper limit value C1 is calculated by the ECU 50 based on the engine speed and the increase amount of the fuel injection amount when the temperature of the engine 20 belongs to a low temperature range. The higher the engine speed, the higher the fuel injection amount. The larger the amount, the smaller the calculation. The temperature of the engine 20 is estimated by the ECU 50 based on, for example, a water temperature sensor 35 that detects the water temperature of the engine 20.

  When the temperature of the engine 20 departs from the low temperature range described above, the factor C is eliminated, and the restriction on the intake air amount by the upper limit value C1 is released after the change-over process. By executing the change-over process, it is possible to suppress deterioration in drivability such as sudden acceleration of the driver unintentionally. The restriction by the upper limit value C1 is released when the upper limit value C1 is equal to or greater than the maximum value M, as in the case of the upper limit value A1.

  Next, the factor D will be described. Factor D is that the air flow meter 15 is abnormal. If there is an abnormality in the air flow meter 15, the intake air amount cannot be detected with high accuracy, so the upper limit of the intake air amount is limited from the viewpoint of safety. The upper limit value D1 is calculated by the ECU 50 based on the engine speed and the like. The determination of the abnormality of the air flow meter 15 is stored in advance based on, for example, whether or not the actual output value of the air flow meter 15 belongs to the normal output range or the intake air amount detected by the air flow meter 15. The ECU 50 makes a determination based on the difference from the intake air amount estimated based on the operating state of the engine 20.

  For example, when the actual output value of the air flow meter 15 belongs to the normal output range, the factor D is eliminated, and the restriction on the intake air amount by the upper limit value D1 is released after the change process. The restriction by the upper limit value D1 is released when the upper limit value D1 becomes equal to or greater than the maximum value M.

  Next, the upper limit of the intake air amount when two or more of these factors A to D are generated will be described. Two or more of these factors A to D may occur in duplicate. In that case, the minimum upper limit value among the upper limit values corresponding to each of the overlapping factors is selected, and the upper limit of the intake air amount is limited by the selected upper limit value. If only the factor corresponding to the selected upper limit value is eliminated and other factors are not eliminated, the minimum upper limit value corresponding to the unresolved factor is selected. This limits the upper limit of the intake air amount.

  Next, a case will be described in which a plurality of such redundant factors are eliminated. Depending on the operating state of the engine 20, a plurality of overlapping factors may be resolved almost simultaneously. In this case, the change-over process is executed only for the minimum upper limit value among the upper limit values respectively corresponding to the eliminated factors.

  FIG. 3 is a timing chart illustrating the release of the upper limit of the intake air amount when both of the two factors A and C are eliminated substantially simultaneously. As shown in FIG. 3, in the state where the factors A and C are generated, the upper limit value A1 is smaller than the upper limit value C1, and therefore the upper limit of the intake air amount is limited by the upper limit value A1, which is the minimum value. When the factors A and C are eliminated, the change process is performed on the upper limit value A1, but the upper process value C1 is released without performing the change process. For example, it is possible to execute the change process for both the upper limit value A1 and the upper limit value C1 and compare the upper limit values A1 and C1 during the change process to limit the upper limit of the intake air amount by the minimum upper limit value. It is done. However, in this case, it is necessary to perform the change process for both the upper limit values A1 and C1, and to compare the upper limit values A1 and C1 during the change process, which increases the processing load on the ECU 50. For this reason, in the present embodiment, when a plurality of factors are resolved substantially simultaneously, the ECU 50 executes a change-over process for the upper limit value selected as the minimum, and for the upper limit value not selected. Therefore, the change process is not executed, and a plurality of upper limit values during the change process are not compared. For this reason, the deterioration of drivability can be suppressed while suppressing an increase in the processing load of the ECU 50.

  In this way, it is only necessary to perform the change process for only the minimum upper limit value among the upper limit values respectively corresponding to the plurality of eliminated factors. For this reason, for example, when adding a restriction on the intake air amount based on a new factor other than the factors A to D to the ECU 50, it is necessary to add a program for calculating an upper limit value corresponding to the new factor. There is no need to add a program for executing change processing on all of the plurality of upper limit values and comparing the plurality of upper limit values during the change processing. For this reason, it becomes easy to add the restriction | limiting based on a new factor to ECU50. For this reason, improvement of ECU50 becomes easy and the increase in the cost accompanying improvement is also suppressed.

  Next, the intake air amount upper limit control executed by the ECU 50 for limiting the upper limit of the intake air amount will be described. FIG. 4 is a flowchart showing an example of intake air amount upper limit control executed by the ECU 50. The ECU 50 determines whether there is a request for limiting the upper limit of the intake air amount (step S1). The restriction request for the upper limit of the intake air amount is requested when any factor occurs. The determination of whether or not a factor has occurred is performed individually according to the type of the factor as described above. If a negative determination is made in step S1, this control is terminated. If the determination in step S1 is affirmative, the ECU 50 limits the intake air amount to be equal to or less than the minimum upper limit value among the upper limit values corresponding to the generated factor (step S2). Here, when only one factor has occurred, the upper limit value corresponding to that factor is selected as the minimum upper limit value. On the other hand, when a plurality of factors occur, the minimum upper limit value among the plurality of upper limit values corresponding to each of the plurality of factors is selected. The process of step S2 is based on the selected upper limit value by selecting the minimum upper limit value among the plurality of upper limit values corresponding to each of the generated multiple factors when the multiple factors have occurred. 5 is an example of processing executed by a limiting unit that limits the intake air amount.

  Next, the ECU 50 determines whether or not the factor corresponding to the upper limit value selected as the minimum upper limit value has been eliminated (step S3). The determination as to whether or not the factor has been eliminated is performed individually according to the type of factor as described above. In the case of negative determination, the processing after step S1 is executed again.

  If the determination in step S3 is affirmative, the ECU 50 determines whether or not a gradual change process is necessary for the selected upper limit value (step S4). This determination is made with reference to a table preliminarily stored in the ROM of the ECU 50 that defines the necessity of the gradual change process associated with the type of factor. FIG. 5 is a diagram illustrating an example of a table stored in the ROM of the ECU 50. In the ROM of the ECU 50, there are factors and whether or not it is necessary to execute a gradual change process that releases the restriction of the intake air amount by the upper limit value by gradually increasing the upper limit value continuously or stepwise when the factor is eliminated. It is an example of the memory | storage part memorize | stored corresponding to every kind of some factor. Moreover, the process of step S4 is an example of the process which the determination part which determines the necessity of execution of the change process with respect to the selected upper limit with reference to ROM of ECU is performed.

  If the determination in step S4 is affirmative, the ECU 50 executes a gradual change process for the selected upper limit value (step S5). The process of step S5 is the case where it is determined that execution of the diversion process for the selected upper limit value is necessary, and when the factor corresponding to the selected upper limit value is resolved, the selected upper limit value It is an example of the process which the removal and change part which performs a change and change process performs. In the case of negative determination in step S4, normal processing for canceling the restriction based on the selected upper limit value is executed without executing the change processing (step S6). After the processing of steps S5 and S6 is completed, step S1 is executed again.

  For example, as shown in FIG. 3, when both of the factors A and C are eliminated substantially simultaneously, the gradual change process is executed only for the upper limit value A1. Since there is no longer a restriction request regarding C, a negative determination is made in step S1 and the present control ends.

  In addition, when only the factor corresponding to the minimum upper limit value among the upper limit values corresponding to each of the plurality of factors occurring at the same time has been eliminated, it is based on the upper limit value after executing the gradual change process or the normal process. The restriction is released, the process of step S2 is executed again, and the intake air amount is restricted by the minimum upper limit value among the upper limit values corresponding to the remaining unresolved factors.

  Next, a modification example of the removal process will be described. FIG. 6 is a timing chart illustrating the upper limit value A1 that is increased by the variable change process of the modification. As shown in FIG. 6, the upper limit value A1 may be increased stepwise. Such a change process may be executed for the upper limit values C1 and D1.

  Although the embodiments of the present invention have been described in detail above, the present invention is not limited to such specific embodiments, and various modifications and changes can be made within the scope of the gist of the present invention described in the claims. It can be changed.

  In addition, in the diversion process, the increase rate of the upper limit value is constant regardless of the factor, but is not limited to this. For example, the increase rate of the upper limit value for each factor of the upper limit value to be subjected to the diversion process is May be different. Even in this case, the changeability process is executed only to the minimum upper limit value among the upper limit values corresponding to each of the plurality of resolved factors, so that the drivability is suppressed while suppressing an increase in the processing load of the ECU 50. Can be suppressed.

1 engine system 50 ECU (storage unit, limiting unit, determination unit, changeover unit)

Claims (1)

In a control device for an internal combustion engine that limits the upper limit of the intake air amount of the internal combustion engine to an upper limit value corresponding to the factor when a predetermined factor has occurred,
The necessity of executing the change process for releasing the restriction of the intake air amount by the upper limit value by gradually increasing the upper limit value continuously or stepwise when the factor is eliminated. A storage unit stored in association with each of a plurality of types of the factors;
When a plurality of the factors are generated, a minimum upper limit value is selected from among the plurality of upper limit values corresponding to each of the generated plurality of factors, and the above-described upper limit value is used to select the above-described upper limit value. A limiting unit that limits the amount of intake air;
A determination unit that refers to the storage unit and determines whether or not to perform the diversion process on the selected upper limit value;
If it is determined that it is necessary to execute the removal process on the selected upper limit value and the factor corresponding to the selected upper limit value is resolved, the selected upper limit value is set. A changer for executing the changeover process;
The control apparatus of the internal combustion engine provided with.

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