JP2013174187A - Internal combustion engine control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress hunting between a fuel cut start and return to self-sustained operation in an internal combustion engine control device by which an opening of a throttle or an idle speed control valve is increased after a control command to start the fuel cut is made.SOLUTION: When hunting occurs between a fuel cut start and return to self-sustained operation within a predetermined period after a control command to start the fuel cut is made, an opening of a throttle or an idle speed control valve is decreased.

Description

  The present invention relates to a control device for an internal combustion engine. More specifically, the present invention relates to an internal combustion engine control device for increasing the opening of a throttle or an idle speed control valve after a control command to start fuel cut, and to start fuel cut and to autonomous operation. The present invention relates to a control device for an internal combustion engine that can suppress hunting during a return.

  In this technical field, an electronic throttle that can control the opening degree regardless of the accelerator pedal is provided, and the pumping loss is adjusted by changing the opening degree of the electronic throttle when the fuel is cut (stopping fuel supply) during driving. A control device for an internal combustion engine that controls deceleration at the time of fuel cut is known (see, for example, Patent Document 1). However, in such a control apparatus for an internal combustion engine according to the prior art, the opening degree of the electronic throttle is increased after the control command for starting the fuel cut is issued and before the fuel cut is actually started. Rather, it is maintained at a constant value. Therefore, there is a problem that a torque down shock that is an impact accompanying a decrease in torque occurs when fuel cut is actually started.

  Therefore, in view of the above problem, in the technical field, for the purpose of providing a control device for an internal combustion engine that can reduce a torque down shock that occurs when fuel cut is actually started, an accelerator pedal and Control of an internal combustion engine equipped with an electronic throttle or idle speed control valve whose opening degree can be controlled regardless of whether the opening degree of the electronic throttle or idle speed control valve is changed when fuel cut during running is started In the control apparatus for an internal combustion engine, the opening degree of the electronic throttle or the idle speed control valve is increased after the control command to start the fuel cut and before the fuel cut is actually started. Has been proposed (see, for example, Patent Document 2).

  In the control device for an internal combustion engine according to the above-described prior art, the electronic throttle or the idle speed control valve is operated after the control command for starting the fuel cut is issued and before the fuel cut is actually started. Opening is increased. Therefore, the torque reduction that occurs when the fuel cut starts and the torque increase that occurs as the opening of the electronic throttle or the idle speed control valve increases are offset. As a result, the opening degree of the electronic throttle or the idle speed control valve is not increased and is maintained at a constant value after the control command to start the fuel cut and before the fuel cut is actually started. Unlike the case, the torque down shock that occurs when the fuel cut is actually started can be reduced. Thereafter, when the internal combustion engine speed decreases due to the fuel cut and the internal combustion engine returns to the idle operation (self-sustaining operation), the fuel cut ends.

  However, the control device for an internal combustion engine according to the above-described prior art regardless of whether the opening of the electronic throttle or the idle speed control valve is actually before or after the fuel cut is started. If the fuel cut is terminated while the opening degree of the electronic throttle or the idle speed control valve remains increased after the control command for starting the fuel cut is issued, the rotational speed of the internal combustion engine increases. In some cases, the engine speed exceeds the target rotational speed during idle operation (self-sustaining operation), reaches the fuel cut speed again, and fuel cut is started again. Thus, if the opening degree of the electronic throttle or the idle speed control valve is increased, hunting may occur between the start of fuel cut and the end of fuel cut (return to independent operation). . When such hunting occurs, problems such as deterioration of drivability (ease of operation) and deterioration of the exhaust gas purification catalyst may occur.

  As described above, in the technical field, in the control device for an internal combustion engine that increases the opening degree of the throttle or the idle speed control valve after the control command to start the fuel cut, the fuel cut start and the autonomous operation are performed. There is a need for a technique that can suppress hunting during the recovery of the system.

JP-A-11-107805 JP 2001-182484 A

  As described above, in the technical field, in the control device for an internal combustion engine that increases the opening degree of the throttle or the idle speed control valve after the control command to start the fuel cut, the fuel cut start and the autonomous operation are performed. There is a need for a technique that can suppress hunting during the recovery of the system. The present invention has been made to meet such a demand. In other words, an object of the present invention is to provide a control device for an internal combustion engine that increases the opening degree of a throttle or an idle speed control valve after a control command to start a fuel cut. It is to suppress hunting between the return.

One object of the present invention is to
A control device for an internal combustion engine having a throttle capable of controlling the opening degree irrespective of an accelerator pedal, wherein the opening degree of the throttle is changed when a fuel cut during operation of the internal combustion engine is started. In the control device for an internal combustion engine that increases the throttle opening after the control command to start
When the start and end of fuel cut are repeated more than a predetermined number of times within a predetermined period after the time when there is a control command to start fuel cut, the throttle opening is decreased. This is achieved by the control device for the internal combustion engine.

Also, the above one object of the present invention is to
Control device for an internal combustion engine having an idle speed control valve capable of controlling the opening degree regardless of the accelerator pedal, and changing the opening degree of the idle speed control valve when fuel cut is started during operation of the internal combustion engine In the control device for an internal combustion engine that increases the opening of the idle speed control valve after there is a control command to start fuel cut,
Decrease the opening of the idle speed control valve when the start and end of fuel cut is repeated more than a predetermined number of times within a predetermined period after the time when there is a control command to start fuel cut This can also be achieved by a control device for an internal combustion engine.

  According to the control apparatus for an internal combustion engine according to the present invention, in the control apparatus for an internal combustion engine that increases the opening degree of the throttle or the idle speed control valve after the control command to start the fuel cut is received, Hunting between returning to operation can be suppressed.

It is a flowchart explaining the flow of each process performed in the determination method of the hunting performed in the control apparatus of the internal combustion engine which concerns on one embodiment of this invention. It is a schematic diagram showing the state of the change of the output request | requirement with respect to an internal combustion engine, the fuel cut flag XFC, and the hunting frequency | count KFC in the state which has generate | occur | produced hunting. It is a flowchart explaining the flow of each process performed in the control method of the opening degree of a throttle or an idle speed control valve based on the determination result of the hunting performed in the control apparatus of the internal combustion engine which concerns on one embodiment of this invention. . Throttle opening correction amount TAFC or idle speed control valve opening correction amount ISCVAFC at the start of fuel cut, and reduction amount of throttle or idle speed control valve opening (that is, throttle opening at the start of fuel cut) It is a typical graph showing the relationship between the correction amount TAFC or the idle speed control valve opening correction amount ISCVAFC).

  As described above, according to the present invention, in the control device for an internal combustion engine that increases the opening degree of the throttle or the idle speed control valve after the control command to start the fuel cut, the fuel cut starts and returns to the independent operation. One object is to suppress hunting between the two. As a result of earnest research to achieve such an object, the present inventor has made a fuel cut in a control device for an internal combustion engine that increases the opening of a throttle or an idle speed control valve after there is a control command to start the fuel cut. If hunting occurs between the start of fuel cut and return to independent operation within a predetermined period after the time when there is a control command to be started, the opening of the throttle or idle speed control valve is adjusted. As a result of the reduction, it has been found that hunting between the start of fuel cut and the return to independent operation can be suppressed, and the present invention has been conceived.

That is, the first embodiment of the present invention is:
A control device for an internal combustion engine having a throttle capable of controlling the opening degree irrespective of an accelerator pedal, wherein the opening degree of the throttle is changed when a fuel cut during operation of the internal combustion engine is started. In the control device for an internal combustion engine that increases the throttle opening after the control command to start
When the start and end of fuel cut are repeated more than a predetermined number of times within a predetermined period after the time when there is a control command to start fuel cut, the throttle opening is decreased. The control device for the internal combustion engine.

  As described above, the control device for an internal combustion engine according to the present embodiment includes a throttle that can control the opening degree regardless of the accelerator pedal, and when the fuel cut during operation of the internal combustion engine is started, the throttle A control device for an internal combustion engine in which the opening degree is changed, and is configured to increase the opening degree of the throttle after a control command to start fuel cut is issued. Since such a configuration is well known in the technical field, no special description is described in this specification.

  With the above configuration, in the control apparatus for an internal combustion engine according to the present embodiment, for example, as described above, the fuel cut is performed by changing the throttle opening and adjusting the pumping loss when the fuel is cut during operation of the internal combustion engine. As the fuel cut starts, the throttle opening is increased after the control command to start the fuel cut and before the actual fuel cut is started. Thus, the torque-down shock generated when the fuel cut is actually started can be reduced by offsetting the torque-down generated and the torque-up generated as the throttle opening increases.

  Further, in the internal combustion engine, for example, when the catalyst is warmed up and racing is performed, the idling ignition timing is retarded and the idling engine speed is increased from the normal time, so that the engine speed and the exhaust gas temperature are increased. When increasing the imbalance detection accuracy by delaying the ignition timing or expanding the overlap of the variable valve timing mechanism (VVT: Variable Valve Timing) when detecting the lean imbalance There is. In these cases, since the torque of the internal combustion engine is lower than normal, the opening degree of the idle speed control valve (or throttle) is increased in order to maintain the rotational speed. In such a state, when the ignition timing is returned (advanced), the rotational speed of the internal combustion engine increases, reaches a predetermined fuel cut rotational speed, and the fuel cut is executed. Thus, when the fuel cut is executed, the rotational speed of the internal combustion engine decreases, and when the internal combustion engine returns to the idle operation (self-sustained operation), the fuel cut ends. At this time, if the opening degree of the idle speed control valve (or throttle) is large as described above, the rotational speed of the internal combustion engine increases again, and the fuel cut is executed again. In this way, hunting occurs between the start of fuel cut and the end of fuel cut (return to independent operation). Even in these cases, if the rotational speed of the internal combustion engine reaches or exceeds a predetermined fuel cut rotational speed, for example, when the accelerator opening decreases, the fuel cut starts, and the throttle ( (Or the idle speed control valve) is increased.

  As described above, under various conditions during operation of the internal combustion engine, the throttle opening may be increased after a control command for starting fuel cut is issued. Thereafter, as described above, the fuel cut ends when the rotational speed of the internal combustion engine decreases due to the fuel cut and the internal combustion engine returns to the idle operation (self-sustaining operation).

  At this time, since the fuel cut is completed with the throttle opening being increased, the supply of fuel is resumed with a large amount of air or air-fuel mixture flowing into the internal combustion engine. In some cases, the rotational speed of the internal combustion engine increases to exceed the original target rotational speed during idle operation (self-sustaining operation), reach the fuel cut rotational speed again, and start the fuel cut again. Thus, when hunting occurs between the start of fuel cut and the end of fuel cut (return to self-sustaining operation), as described above, for example, deterioration of drivability, deterioration of exhaust gas purification catalyst, etc. May cause problems.

  However, in the control apparatus for an internal combustion engine according to the present embodiment, when hunting occurs between the start of fuel cut and the end of fuel cut (return to self-sustained operation) as described above, the throttle is opened. The degree is reduced. More specifically, as described above, the control device for an internal combustion engine according to the present embodiment starts and ends the fuel cut within a predetermined period after the time when there is a control command to start the fuel cut. Is repeated for a predetermined number of times or more, the throttle opening is reduced. Thereby, in the control device for an internal combustion engine according to the present embodiment, the supply of fuel is resumed in a state where a large amount of air or air-fuel mixture flows into the internal combustion engine as described above, and the rotational speed of the internal combustion engine is increased. Increases, exceeding the original target rotational speed during idle operation, and the problem of hunting occurring between the start of fuel cut and return to independent operation can be suppressed. As a result, it is possible to reduce problems such as deterioration of drivability and deterioration of the exhaust gas purification catalyst due to such hunting.

  By the way, in the control apparatus for an internal combustion engine according to the present embodiment, the start and end of the fuel cut are repeated a predetermined number of times within a predetermined period after the time when there is a control command to start the fuel cut. If this happens, reduce the throttle opening. Here, the predetermined period after the time when there is a control command to start the fuel cut can be appropriately determined based on the engine speed at the start of the fuel cut, for example. The predetermined number of times, which is a threshold value of the number of times the fuel cut is started and ended when the throttle opening is decreased, can be appropriately determined based on the amount of overshoot or undershoot, for example. . Further, the predetermined number of times may be, for example, a fixed value determined in advance as described above. Alternatively, the predetermined number of times is, for example, the number of revolutions of the internal combustion engine at the time when there is a control command to start fuel cut, the target of the internal combustion engine at the time when there is a control command to start fuel cut State quantity of the internal combustion engine such as the rotational speed (which may be a command rotational speed when the internal combustion engine is mounted on a hybrid vehicle (HV)), for example, a fuel cut rotational speed, an idle rotational speed (return rotational speed) ) Or the like may be determined as a variation value that varies according to a set value set in the internal combustion engine. For example, the predetermined number of times may be set to decrease as the amount of overshoot or undershoot increases. In addition, when the internal combustion engine is mounted on a hybrid vehicle (HV), for example, it may be set based on the allowable rotation speed of a planetary gear or an electric motor.

  In addition, it is determined whether or not the start and end of the fuel cut have been repeated a predetermined number of times within a predetermined period after the time when there is a control command to start the fuel cut (that is, the start of the fuel cut) The determination of whether or not hunting has occurred between the return to the independent operation and the return to the independent operation can be performed as follows, for example. In an electronic control unit (ECU: Electronic Control Unit) included in the control device of the internal combustion engine, it is determined whether or not there is an output request for the internal combustion engine (for example, accelerator opening AC = 0 (zero)), and output to the internal combustion engine When there is no request, the number of times the fuel cut starts and ends within a predetermined period after the time when there is a control command to start the fuel cut (for example, ON / OFF of the fuel cut flag XFC) If the count result is equal to or greater than a predetermined number, it can be determined that the hunting has occurred (details will be described later).

  Further, the process of decreasing the throttle opening based on the above determination can be executed as follows, for example. First, after there is a control command (fuel cut flag XFC = ON) to start the fuel cut, the electronic control unit ECU included in the control device for the internal combustion engine, for example, sets the throttle opening TAIDL during the idling operation of the internal combustion engine. By issuing a control command (TA ← TAIDL + TAFC) to the electronically controlled throttle provided in the internal combustion engine, a control command for setting the throttle opening TA to the throttle opening obtained by adding the correction amount TAFC of the throttle opening at the start of fuel cut (TA ← TAIDL + TAFC) Assume that TA is increased. Thereafter, when the rotational speed NE detected by the rotational speed detection means for detecting the rotational speed of the internal combustion engine decreases due to the fuel cut, and the internal combustion engine returns to the idle operation (self-sustained operation), the fuel cut ends (fuel cut). Flag XFC = OFF). Thereafter, when it is determined that hunting has occurred as described above, the electronic control unit ECU can decrease the throttle opening TA, for example, by changing the throttle opening correction amount TAFC to a smaller value. it can. Alternatively, when feedback control based on the rotational speed NE of the internal combustion engine is performed, for example, the feedback correction amount included in the throttle opening of the internal combustion engine is operated to adjust the throttle opening as described above. Can do. For example, the throttle opening correction amount TAFC associated with the start of fuel cut may be added to the feedback correction amount TAFB added to the throttle opening TAIDL during the idling operation of the internal combustion engine (TAFB ← TAFB + TAFC).

  The algorithm including determination and control as described above is, for example, a data storage device (for example, a ROM (Read-Only Memory), a RAM (Random Access Memory), or the like) included in an electronic control unit ECU included in a control device for an internal combustion engine. ) Can be executed by a central processing unit (CPU) included in the electronic control unit ECU. Furthermore, in the above description, the embodiment in which the determination and control as described above are executed in the electronic control unit ECU included in the control device of the internal combustion engine has been described. For example, the determination and control as described above are performed in the internal combustion engine. You may perform in a control apparatus different from electronic control apparatus ECU with which a control apparatus is provided. Furthermore, the process for performing the determination and control as described above can be executed by the control device as an interrupt process for each predetermined crank angle, for example.

  By the way, as described above, the control device for an internal combustion engine according to the present embodiment has predetermined start and end of the fuel cut within a predetermined period after the time when there is a control command to start the fuel cut. If it is repeated more than once, the throttle opening is decreased. In this case, the throttle opening after the decrease can be the opening before the throttle opening is increased after the control command to start the fuel cut. In other words, when the hunting occurs between the start of the fuel cut and the return to the independent operation, the amount of decrease in the throttle opening is actually after the control command to start the fuel cut. The amount corresponding to the increase of the throttle opening increased before the fuel cut is started.

That is, the second embodiment of the present invention is:
A control device for an internal combustion engine according to the first embodiment of the present invention, comprising:
There is a control command to start a fuel cut when the start and end of the fuel cut are repeated a predetermined number of times within a predetermined period after the time when there is a control command to start the fuel cut. After that, the control device for the internal combustion engine is configured to decrease the throttle opening by an amount corresponding to the increase in the throttle opening increased before the fuel cut is actually started.

  As described above, the control device for an internal combustion engine according to the present embodiment performs the predetermined number of times the start and end of the fuel cut within a predetermined period after the time when there is a control command to start the fuel cut. When the above is repeated, after the control command to start the fuel cut, there is an amount corresponding to the increase in the throttle opening increased before the fuel cut is actually started. It is configured to reduce the opening. In other words, when the hunting occurs between the start of the fuel cut and the return to the independent operation, the throttle opening after being reduced by the control device for the internal combustion engine according to the present embodiment is the fuel cut. This is equivalent to the opening before the throttle opening is increased after the control command to be started. Thereby, in the control apparatus for an internal combustion engine according to the present embodiment, when hunting occurs between the start of fuel cut and the return to the self-sustaining operation, the opening of the throttle is quickly reduced, and the control is performed. Hunting can be suppressed quickly, and the speed of the internal combustion engine can be brought close to the target speed.

  By the way, when hunting occurs between the start of fuel cut and the return to independent operation as described above, if the throttle opening is reduced at once after a control command to start fuel cut, For example, there is a risk that a drop in the rotational speed of the internal combustion engine, or in the worst case, a stop (engine stall) of the internal combustion engine due to misfire may occur. In order to suppress such a problem, when hunting as described above occurs, the opening degree is equivalent to the opening degree before the throttle opening degree is increased after the control command to start the fuel cut is issued. It is desirable to gradually reduce the throttle opening, rather than reducing the throttle opening at once.

That is, the third embodiment of the present invention
A control device for an internal combustion engine according to the first embodiment of the present invention, comprising:
When the start and end of the fuel cut are repeated a predetermined number of times within a predetermined period after the time when there is a control command to start the fuel cut, the throttle is opened by a predetermined amount. This is a control device for an internal combustion engine in which the degree is reduced.

  As described above, the control device for an internal combustion engine according to the present embodiment performs the predetermined number of times the start and end of the fuel cut within a predetermined period after the time when there is a control command to start the fuel cut. When it is repeated, the throttle opening is reduced by a predetermined amount. The predetermined amount may be a predetermined fixed value, for example. Alternatively, the predetermined amount is, for example, when the throttle opening correction amount TAFC or the idle speed control valve opening correction amount ISCVAFC accompanying the start of the fuel cut, or when there is a control command to start the fuel cut. Of the internal combustion engine and the target rotational speed of the internal combustion engine at the time when there is a control command to start the fuel cut (even if the rotational speed is the command rotational speed when the internal combustion engine is mounted on a hybrid vehicle (HV)) It may be a variable value that varies in accordance with the state quantity of the internal combustion engine, such as a fuel cut speed, a set value set for the internal combustion engine, such as an idle speed (return speed), or the like.

  The predetermined amount is, for example, a value set so as to decrease as the deviation between the throttle opening correction amount TAFC accompanying the start of fuel cut or the internal combustion engine speed and the target engine speed increases. Also good. Advantages of setting the predetermined amount in this way include, for example, that it is possible to suppress the internal combustion engine from being blown up when the fuel cut is performed and the vehicle returns to the independent operation. Can do.

  Alternatively, the predetermined amount is, for example, a value set so as to increase as the deviation between the throttle opening correction amount TAFC accompanying the start of the fuel cut or the rotational speed of the internal combustion engine and the target rotational speed increases. It may be. Advantages of setting the predetermined amount in this way include, for example, the ability to more quickly converge hunting between the start of fuel cut and return to independent operation. .

  By the way, as described above, the control device for an internal combustion engine according to the above-described embodiment of the present invention starts and ends the fuel cut within a predetermined period after the time when there is a control command to start the fuel cut. Is repeated more than a predetermined number of times, the throttle opening is decreased. At this time, if the throttle opening is reduced indefinitely, the rotational speed of the internal combustion engine decreases due to fuel cut, and the throttle opening is excessively reduced when the internal combustion engine should return to idle operation (self-sustaining operation). For this reason, stable idle operation cannot be maintained, and the rotation of the internal combustion engine may become unstable. From this point of view, it is desirable to provide a lower limit for the throttle opening when the throttle opening is reduced when hunting occurs between the start of fuel cut and the return to independent operation.

Therefore, the fourth embodiment of the present invention is
An internal combustion engine control apparatus according to any one of the first to third embodiments of the present invention,
When the start and end of the fuel cut are repeated a predetermined number of times within a predetermined period after the time when there is a control command to start the fuel cut, the above is less than a predetermined lower limit value. This is a control device for an internal combustion engine in which the opening of the throttle is not reduced.

  As described above, the control device for an internal combustion engine according to the present embodiment performs the predetermined number of times the start and end of the fuel cut within a predetermined period after the time when there is a control command to start the fuel cut. When it is repeated as described above, the throttle opening is not reduced until less than a predetermined lower limit value. Thus, in the control apparatus for an internal combustion engine according to the present embodiment, when the throttle opening is reduced when hunting occurs between the start of fuel cut and the return to the independent operation, the throttle opening is reduced. It is possible to prevent the degree from being excessively reduced. As a result, the rotational speed of the internal combustion engine decreases due to the fuel cut, and the internal combustion engine should return to idle operation (self-sustained operation). However, the throttle opening is excessively decreased, so that stable idle operation is maintained. This can prevent the problem that the rotation of the internal combustion engine becomes unstable.

  The predetermined lower limit value (TALOW) may be set as a value smaller by a predetermined value (ΔTA1) than the throttle opening degree TAIDL during idling operation of the internal combustion engine (TALOW ← TAIDL), for example. -ΔTA1). Alternatively, when feedback control based on the rotational speed NE of the internal combustion engine is performed, the predetermined lower limit value TALOW is, for example, from a feedback correction amount TAFB added to the throttle opening degree TAIDL during idling operation of the internal combustion engine. May be set as a value smaller by a predetermined value (ΔTA2) (TALOW ← TAIDL + TAFB−ΔTA2).

  As described above, an internal combustion engine having a throttle whose opening degree can be controlled regardless of the accelerator pedal so that the opening degree of the throttle is changed when fuel cut is started during operation of the internal combustion engine. In the control apparatus for an internal combustion engine in which the opening degree of the throttle is increased after the control command for starting the fuel cut is issued, the control device after the time when the control command for starting the fuel cut is received. Various embodiments of a control device for an internal combustion engine configured to decrease the opening of the throttle when the start and end of a fuel cut are repeated a predetermined number of times or more within a predetermined period I have explained.

  However, in an internal combustion engine having an idle speed control valve, the opening of the idle speed control valve is controlled instead of or in addition to the opening of the throttle. The goal can also be achieved. Therefore, an embodiment that achieves one object of the present invention described above by controlling the opening degree of the idle speed control valve in an internal combustion engine equipped with the idle speed control valve will be described below.

First, the fifth embodiment of the present invention is:
Control device for an internal combustion engine having an idle speed control valve capable of controlling the opening degree regardless of the accelerator pedal, and changing the opening degree of the idle speed control valve when fuel cut is started during operation of the internal combustion engine In the control device for an internal combustion engine that increases the opening of the idle speed control valve after there is a control command to start fuel cut,
Decrease the opening of the idle speed control valve when the start and end of fuel cut is repeated more than a predetermined number of times within a predetermined period after the time when there is a control command to start fuel cut A control device for an internal combustion engine.

  As described above, the control device for an internal combustion engine according to the present embodiment includes the idle speed control valve capable of controlling the opening degree regardless of the accelerator pedal, and starts fuel cut during operation of the internal combustion engine. A control device for an internal combustion engine in which the opening degree of the idle speed control valve is sometimes changed, and is configured to increase the opening degree of the idle speed control valve after receiving a control command to start fuel cut. Since such a configuration is well known in the technical field, no special description is described in this specification.

  With the above configuration, in the control apparatus for an internal combustion engine according to the present embodiment, for example, at the time of fuel cut by changing the opening of the idle speed control valve and adjusting the pumping loss at the time of fuel cut during operation of the internal combustion engine. The fuel cut can be started by increasing the opening of the idle speed control valve after controlling the deceleration or after the control command to start the fuel cut but before actually starting the fuel cut. Torque-down shock that occurs when fuel cut is actually started is reduced by offsetting the torque-down that occurs with the torque-up that occurs as the opening of the idle speed control valve increases. be able to.

  Furthermore, in the control apparatus for an internal combustion engine according to the present embodiment, the amount of inflow of air or air-fuel mixture into the internal combustion engine is increased by the above configuration, for example, the rotation of the internal combustion engine during catalyst warm-up and when racing is performed. It is also possible to increase the number and the temperature of the exhaust gas, or to increase the rotational speed of the internal combustion engine in order to make a secondary determination when the lean imbalance is detected. Even in these cases, if the rotational speed of the internal combustion engine reaches or exceeds a predetermined fuel cut rotational speed, the fuel cut is started, for example, when the accelerator opening decreases, and the idle speed The opening of the control valve is increased.

  As described above, under various circumstances during the operation of the internal combustion engine, the opening degree of the idle speed control valve may be increased after there is a control command to start the fuel cut. Thereafter, as described above, the fuel cut ends when the rotational speed of the internal combustion engine decreases due to the fuel cut and the internal combustion engine returns to the idle operation (self-sustaining operation).

  At this time, since the fuel cut is completed with the opening degree of the idle speed control valve being increased, the fuel supply is performed with a large amount of air or air-fuel mixture flowing into the internal combustion engine. Is restarted, the internal combustion engine speed increases, exceeds the original target speed during idle operation (self-sustaining operation), reaches the fuel cut speed again, and fuel cut may be started again. Thus, when hunting occurs between the start of fuel cut and the end of fuel cut (return to self-sustaining operation), as described above, for example, deterioration of drivability, deterioration of exhaust gas purification catalyst, etc. May cause problems.

  However, in the control apparatus for an internal combustion engine according to the present embodiment, when hunting occurs between the start of fuel cut and the end of fuel cut (return to self-sustained operation) as described above, the idle speed control is performed. The valve opening is reduced. More specifically, as described above, the control device for an internal combustion engine according to the present embodiment starts and ends the fuel cut within a predetermined period after the time when there is a control command to start the fuel cut. Is repeated more than a predetermined number of times, the opening degree of the idle speed control valve is decreased. Thereby, in the control device for an internal combustion engine according to the present embodiment, the supply of fuel is resumed in a state where a large amount of air or air-fuel mixture flows into the internal combustion engine as described above, and the rotational speed of the internal combustion engine is increased. Increases, exceeding the original target rotational speed during idle operation, and the problem of hunting occurring between the start of fuel cut and return to independent operation can be suppressed. As a result, it is possible to reduce problems such as deterioration of drivability and deterioration of the exhaust gas purification catalyst due to such hunting.

  By the way, in the control apparatus for an internal combustion engine according to the present embodiment, the start and end of the fuel cut are repeated a predetermined number of times within a predetermined period after the time when there is a control command to start the fuel cut. If this happens, reduce the opening of the idle speed control valve. Here, the predetermined period after the time when there is a control command to start the fuel cut can be appropriately determined based on the engine speed at the start of the fuel cut, for example. Further, the predetermined number of times, which is a threshold value of the number of times the fuel cut is started and ended when the opening of the idle speed control valve is decreased, is appropriately determined based on, for example, the amount of overshoot or undershoot. be able to. Further, the predetermined number of times may be, for example, a fixed value determined in advance as described above. Alternatively, the predetermined number of times is, for example, the number of revolutions of the internal combustion engine at the time when there is a control command to start fuel cut, the target of the internal combustion engine at the time when there is a control command to start fuel cut State quantity of the internal combustion engine such as the rotational speed (which may be a command rotational speed when the internal combustion engine is mounted on a hybrid vehicle (HV)), for example, a fuel cut rotational speed, an idle rotational speed (return rotational speed) ) Or the like may be determined as a variation value that varies according to a set value set in the internal combustion engine. For example, the predetermined number of times may be set to decrease as the amount of overshoot or undershoot increases. In addition, when the internal combustion engine is mounted on a hybrid vehicle (HV), for example, it may be set based on the allowable rotation speed of a planetary gear or an electric motor.

  In addition, it is determined whether or not the start and end of the fuel cut have been repeated a predetermined number of times within a predetermined period after the time when there is a control command to start the fuel cut (that is, the start of the fuel cut) As described above, for example, in the electronic control unit ECU included in the control device of the internal combustion engine, there is no output request to the internal combustion engine (determination of whether or not hunting has occurred between the return to the self-sustained operation) ( For example, it is determined whether or not the accelerator opening degree AC = 0 (zero)), and when there is no output request to the internal combustion engine, within a predetermined period after the time when there is a control command to start the fuel cut The number of times the start and end of the fuel cut is repeated (for example, the number of times the fuel cut flag XFC is turned ON and OFF) is counted, and the count result is determined in advance. If it is above, (will be described later in detail) can be determined that the hunting has occurred.

  Moreover, the process which reduces the opening degree of an idle speed control valve based on the above determinations can be performed as follows, for example. First, the electronic control unit ECU provided in the control device for the internal combustion engine, for example, opens the idle speed control valve during the idling operation of the internal combustion engine after the control command (fuel cut flag XFC = ON) to start the fuel cut. An electronically controlled idle speed control valve in which the internal combustion engine has a control command for setting the idle speed control valve opening degree ISCVA to the idle speed control valve opening degree correction amount ISCVAFC added to the degree ISCVAIDL when the fuel cut is started (ISCVA ← ISCVAIDL + ISCVAFC) to increase the idle speed control valve opening ISCVA.

  Thereafter, when the rotational speed NE detected by the rotational speed detection means for detecting the rotational speed of the internal combustion engine decreases due to the fuel cut, and the internal combustion engine returns to the idle operation (self-sustained operation), the fuel cut ends (fuel cut). Flag XFC = OFF). Thereafter, when it is determined that hunting has occurred as described above, the electronic control unit ECU changes the idle speed control valve opening correction amount ISCVAFC to a smaller value, for example, thereby changing the idle speed control valve opening degree. ISCVA can be reduced. Alternatively, when feedback control based on the rotational speed NE of the internal combustion engine is performed, for example, the feedback correction amount included in the idle speed control valve opening of the internal combustion engine is operated to open the idle speed control valve as described above. The degree can be adjusted. For example, the idle speed control valve opening correction amount ISCVAFC accompanying the start of fuel cut may be added to the feedback correction amount ISCVAFB added to the idle speed control valve opening ISCVAIDL during the idling operation of the internal combustion engine (ISCVAFB ← ISCVAFB + ISCVAFC).

  The algorithm including the determination and control as described above is, for example, a program stored in a data storage device (eg, ROM, RAM, etc.) provided in an electronic control device ECU provided in a control device for an internal combustion engine, as described above. Thus, the CPU can be executed by the central processing unit CPU provided in the electronic control unit ECU. Furthermore, in the above description, the embodiment in which the determination and control as described above are executed in the electronic control unit ECU included in the control device of the internal combustion engine has been described. For example, the determination and control as described above are performed in the internal combustion engine. You may perform in a control apparatus different from electronic control apparatus ECU with which a control apparatus is provided. Furthermore, the process for performing the determination and control as described above can be executed by the control device as an interrupt process for each predetermined crank angle, for example.

  By the way, as described above, the control device for an internal combustion engine according to the present embodiment has predetermined start and end of the fuel cut within a predetermined period after the time when there is a control command to start the fuel cut. When it is repeated more than once, the opening of the idle speed control valve is decreased. At this time, the opening degree of the idle speed control valve after the reduction can be set to the opening degree before the opening degree of the idle speed control valve is increased after the control command to start the fuel cut. In other words, the amount of decrease in the opening of the idle speed control valve when hunting occurs between the start of fuel cut and return to independent operation is determined after there is a control command to start fuel cut. Therefore, it can be set to an amount corresponding to the increase in the opening of the idle speed control valve that is increased before the fuel cut is actually started.

That is, the sixth embodiment of the present invention
A control device for an internal combustion engine according to the fifth embodiment of the present invention, comprising:
There is a control command to start a fuel cut when the start and end of the fuel cut are repeated a predetermined number of times within a predetermined period after the time when there is a control command to start the fuel cut. An internal combustion engine in which the opening of the idle speed control valve is decreased by an amount corresponding to an increase in the opening of the idle speed control valve that is increased after the actual fuel cut is started. It is a control device.

  By the way, when hunting occurs between the start of fuel cut and return to independent operation as described above, the opening of the idle speed control valve is increased after a control command to start fuel cut is issued. If the opening of the idle speed control valve is suddenly reduced to an opening equivalent to the opening before the start, for example, when the fuel cut is resumed immediately after that, there is a possibility that the torque down shock as described above may occur. is there. In order to suppress such a problem, when the hunting as described above occurs, it is equivalent to the opening before the opening of the idle speed control valve is increased after there is a control command to start the fuel cut. It is desirable to gradually reduce the opening of the idle speed control valve rather than reducing the opening of the idle speed control valve to the opening.

That is, the seventh embodiment of the present invention is
A control device for an internal combustion engine according to the fifth embodiment of the present invention, comprising:
When the start and end of the fuel cut are repeated a predetermined number of times within a predetermined period after the time when there is a control command to start the fuel cut, the idle speed control is performed by a predetermined amount. This is a control device for an internal combustion engine that reduces the opening of the valve.

  As described above, the control device for an internal combustion engine according to the present embodiment performs the predetermined number of times the start and end of the fuel cut within a predetermined period after the time when there is a control command to start the fuel cut. When repeated, the opening of the idle speed control valve is decreased by a predetermined amount. The predetermined amount may be a predetermined fixed value, for example. Alternatively, the predetermined amount may be, for example, the idle speed control valve opening increased after the control command to start the fuel cut, the internal combustion at the time of the control command to start the fuel cut. The engine speed and the target speed of the internal combustion engine at the time when there is a control command to start fuel cut (if the internal combustion engine is mounted on a hybrid vehicle (HV), it may be the command speed) It may be a fluctuating value that fluctuates in accordance with the state quantity of the internal combustion engine such as, for example, a set value set in the internal combustion engine such as a fuel cut rotational speed or an idle rotational speed (return rotational speed).

  The predetermined amount is, for example, a correction amount ISCVAFC of the opening speed of the idle speed control valve increased after a control command to start fuel cut or a deviation between the engine speed and the target engine speed. The value may be set so as to decrease as the value increases. Advantages of setting the predetermined amount in this way include, for example, that it is possible to suppress the internal combustion engine from being blown up when the fuel cut is performed and the vehicle returns to the independent operation. Can do.

  Alternatively, the predetermined amount is, for example, an idle speed control valve opening correction amount ISCVAFC increased after a control command to start fuel cut or an internal combustion engine speed and a target speed. The value may be set so as to increase as the deviation increases. Advantages of setting the predetermined amount in this way include, for example, the ability to more quickly converge hunting between the start of fuel cut and return to independent operation. .

  By the way, as described above, the control device for an internal combustion engine according to the above-described embodiment of the present invention starts and ends the fuel cut within a predetermined period after the time when there is a control command to start the fuel cut. Is repeated more than a predetermined number of times, the opening of the idle speed control valve is decreased. At this time, if the opening of the idle speed control valve is reduced indefinitely, the speed of the internal combustion engine decreases due to the fuel cut, and the internal speed of the internal combustion engine should return to idle operation (self-sustaining operation). Since the degree is excessively reduced, stable idle operation cannot be maintained, and the rotation of the internal combustion engine may become unstable. From this point of view, when hunting occurs between the start of fuel cut and return to independent operation, when the opening of the idle speed control valve is decreased, a lower limit is set for the opening of the idle speed control valve. It is desirable to provide it.

Accordingly, the eighth embodiment of the present invention provides:
An internal combustion engine control apparatus according to any one of the fifth to seventh embodiments of the present invention,
When the start and end of the fuel cut are repeated a predetermined number of times within a predetermined period after the time when there is a control command to start the fuel cut, the above is less than a predetermined lower limit value. A control device for an internal combustion engine that does not decrease the opening of an idle speed control valve.

  As described above, the control device for an internal combustion engine according to the present embodiment performs the predetermined number of times the start and end of the fuel cut within a predetermined period after the time when there is a control command to start the fuel cut. When it repeats above, it is comprised so that the opening degree of the said idle speed control valve may not be decreased until less than a predetermined lower limit. Thereby, in the control device for the internal combustion engine according to the present embodiment, when hunting occurs between the start of fuel cut and the return to the independent operation, when the opening of the idle speed control valve is reduced, It is possible to prevent the opening degree of the idle speed control valve from being excessively reduced. As a result, the speed of the internal combustion engine decreases due to the fuel cut, and the internal combustion engine should return to idle operation (self-sustaining operation). However, since the opening of the idle speed control valve is excessively reduced, stable idle operation is achieved. Cannot be maintained, and the problem of unstable rotation of the internal combustion engine can be suppressed.

  The predetermined lower limit value (ISCVALOW) may be set as a value smaller by a predetermined value (ΔISCVA1) than, for example, an idle speed control valve opening ISCVAIDL during idling operation of the internal combustion engine ( ISCVALOW ← ISCVAIDL-ΔISCVA1). Alternatively, when feedback control based on the rotational speed NE of the internal combustion engine is performed, the predetermined lower limit value ISCVALOW is added to, for example, the idle speed control valve opening ISCVAIDL during idling operation of the internal combustion engine. It may be set as a value smaller than the amount ISCVAFB by a predetermined value (ΔTA2) (ISCVALOW ← ISCVAIDL + ISCVAFB−ΔISCVA2).

  The configuration of the assembled battery according to some embodiments of the present invention will be described below with reference to the accompanying drawings. However, the following description is for illustrative purposes only, and the scope of the present invention should not be construed as being limited to the following description.

1. Determination of Hunting As described above, in the control apparatus for an internal combustion engine according to the present invention, it is determined whether hunting has occurred between the start of fuel cut and the return to independent operation. More specifically, in the control device for an internal combustion engine according to the present invention, the start and end of the fuel cut are predetermined within a predetermined period after the time when there is a control command for starting the fuel cut. It is determined whether or not it has been repeated more than once.

  The above determination will be described in detail below with reference to the accompanying drawings. FIG. 1 is a flowchart illustrating the flow of each process executed in the hunting determination method executed in the control device for an internal combustion engine according to one embodiment of the present invention as described above. In the hunting determination method shown in FIG. 1, first, in step S101, it is determined whether or not there is no output request to the internal combustion engine (for example, accelerator opening AC = 0 (zero)).

  If it is determined in step S101 that there is no output request for the internal combustion engine (step S101: Yes), is the fuel cut being executed in the next step S102 (ie, fuel cut flag XFC = ON)? It is determined whether or not. On the other hand, if it is determined in step S101 that there is an output request for the internal combustion engine (step S101: No), the fuel cut is not executed in the first place. Therefore, in the next step S108, for example, the fuel cut flag XFC is turned on and off. The number of times the start and end of the fuel cut counted by the number of repetitions of the fuel cut (that is, the number of huntings) is cleared (returned to 0 (zero)), and there is no hunting in the next step S109 The judgment result is given.

  If it is determined in step S102 that a fuel cut is being performed (that is, XFC = ON) (step S102: Yes), in the next step S103, the fuel cut is performed when the hunting determination routine is executed last time. It is determined whether or not the state has not been executed (that is, the previous time XFC = OFF). If it is determined in step S103 that the fuel cut has not been executed when the hunting determination routine was executed last time (that is, the previous XFC = OFF) (step S103: Yes), hunting has occurred. In step S104, the hunting count KFC is incremented (KFC ← KFC + 1). On the other hand, when it is not determined in step S103 that the fuel cut was not performed when the hunting determination routine was executed last time (that is, the previous XFC = OFF) (step S103: No), The next step S104 is skipped, and the count of the hunting count KFC is not increased.

  Here, how the output request to the internal combustion engine, the fuel cut flag XFC, and the hunting frequency KFC change in a state where hunting is occurring will be described with reference to FIG. FIG. 2 is a schematic diagram showing changes in the output request to the internal combustion engine, the fuel cut flag XFC, and the hunting count KFC in the state where hunting is occurring as described above. As shown in FIG. 2, in a state where the rotational speed of the internal combustion engine is equal to or higher than the rotational speed determined as the fuel cut rotational speed, when the output request to the internal combustion engine becomes 0 (zero), the fuel cut flag XFC is turned from OFF to ON. Switch to Thereafter, when hunting occurs as described above, the fuel cut flag XFC repeats OFF and ON. Accordingly, since the count of the hunting frequency KFC is increased as described above, the value of the hunting frequency KFC increases every time hunting occurs.

  Next, in the next step S105, it is determined whether or not the number of huntings KFC is equal to or greater than a predetermined number KFCC. If it is determined in step S105 that the number of huntings KFC is equal to or greater than a predetermined number of times KFCC (ie, KFC ≧ KFCC) (step S105: Yes), it is determined in step S106 that hunting is present. On the other hand, if it is determined in step S105 that the number of huntings KFC is less than the predetermined number of times KFCC (ie, KFC <KFCC) (step S105: No), the current hunting determination routine is temporarily terminated and the next time In the hunting determination routine, hunting is determined again.

  On the other hand, when it is determined in step S102 that the fuel cut has not been executed (that is, XFC = OFF) (step S102: No), in the next step S107, the fuel cut has not been executed (ie, the fuel cut is not executed). It is determined whether or not (the state where XFC = OFF) continues for a predetermined period or longer. If it is determined in step S107 that the fuel cut has not been executed (XFC = OFF) for a predetermined period or longer (step S107: Yes), the fuel cut is completed and the internal combustion engine is turned on. Since it is considered that the vehicle has already returned to normal idle operation (self-sustained operation), the count of the hunting frequency KFC is cleared (returned to 0 (zero)) in the next step S108, and no hunting is detected in the next step S109. judge.

  On the other hand, if it is determined in step S107 that the fuel cut is not being executed (XFC = OFF) for a predetermined period or longer (step S107: No), the rotation of the internal combustion engine will be performed in the future. There is a possibility that the number will rise and reach the fuel cut speed again, and fuel cut may be started again. Therefore, the current hunting determination routine is temporarily terminated, and the hunting determination is performed again in the next hunting determination routine.

  As described above, according to the procedure shown in the flowchart of FIG. 1, the control device for an internal combustion engine in which the opening of the throttle or the idle speed control valve is changed when the fuel cut during the operation of the internal combustion engine is started. In a control device for an internal combustion engine that increases the opening of a throttle or an idle speed control valve after a control command to start fuel cut, the time after the control command to start fuel cut is Whether fuel cut start and end have been repeated more than a predetermined number of times within a predetermined period (that is, whether hunting occurs between the start of fuel cut and return to autonomous operation) Can be reliably determined.

  As described above, the predetermined period after the time when there is a control command to start the fuel cut can be appropriately determined based on, for example, the engine speed at the start of the fuel cut. Further, the predetermined number of times, which is a threshold of the number of times the fuel cut starts and ends when the throttle or idle speed control valve opening is decreased, is based on, for example, the amount of overshoot or undershoot. It can be determined as appropriate. Further, the predetermined number of times may be, for example, a fixed value determined in advance as described above. Alternatively, the predetermined number of times is, for example, the number of revolutions of the internal combustion engine at the time when there is a control command to start fuel cut, the target of the internal combustion engine at the time when there is a control command to start fuel cut State quantity of the internal combustion engine such as the rotational speed (which may be a command rotational speed when the internal combustion engine is mounted on a hybrid vehicle (HV)), for example, a fuel cut rotational speed, an idle rotational speed (return rotational speed) ) Or the like may be determined as a variation value that varies according to a set value set in the internal combustion engine. For example, the predetermined number of times may be set to decrease as the amount of overshoot or undershoot increases. In addition, when the internal combustion engine is mounted on a hybrid vehicle (HV), for example, it may be set based on the allowable rotation speed of a planetary gear or an electric motor.

  The algorithm for performing the determination as described above is, for example, in accordance with a program stored in a data storage device (eg, ROM, RAM, etc.) provided in the electronic control device ECU provided in the control device of the internal combustion engine. Can be executed by a central processing unit CPU included in the CPU. Further, the determination as described above may be executed by the electronic control unit ECU included in the control unit for the internal combustion engine, or may be executed by a control unit separate from the electronic control unit ECU included in the control unit for the internal combustion engine. Good. Furthermore, the process for performing the determination as described above can be executed by the control device as an interrupt process for each predetermined crank angle, for example.

2. Control of the opening of the throttle or idle speed control valve Next, the control of the opening of the throttle or idle speed control valve when the occurrence of hunting is determined as described above will be described in detail below with reference to the accompanying drawings. explain. As described above, FIG. 3 shows each of the throttle or idle speed control valve opening degree control methods executed in the control method for the internal combustion engine according to one embodiment of the present invention. It is a flowchart explaining the flow of a process.

  In the control method shown in FIG. 3, first, in step S301, the start and end of fuel cut are determined in advance within a predetermined period after the time when there is a control command to start fuel cut (XFC ← ON). It is determined whether it has been repeated more than the number of times (KFCC) (that is, whether hunting has occurred). This determination can be performed by the method described with reference to FIGS. 1 and 2 in the above-described embodiment, for example. If it is determined in step S301 that hunting has not occurred (step S301: No), the idling operation (self-sustaining operation) of the internal combustion engine is stable, and the internal combustion engine will eventually respond to an output request to the internal combustion engine. Since the operation state is appropriately controlled (may be accompanied by the feedback control described above), normal control is executed in the next step S304. That is, when it is determined in step S301 that hunting has not occurred (step S301: No), control for forcibly decreasing the opening of the throttle or idle speed control valve is not performed.

  On the other hand, when it is determined in step S301 that hunting has occurred (step S301: Yes), in the next step S302, control is performed to increase the opening of the throttle or the idle speed control valve as the fuel cut starts. It is determined whether or not the operation has been performed.

  More specifically, in step S302, for example, the throttle opening degree TA is obtained by adding a throttle opening degree correction amount TAFC associated with the start of fuel cut to the throttle opening degree TAIDL during idling of the internal combustion engine. By issuing a command to the electronic control throttle provided in the internal combustion engine (TA ← TAIDL + TAFC), it is determined whether or not the throttle opening degree TA has been increased. Alternatively, in step S302, for example, the idle speed control valve opening obtained by adding the idle speed control valve opening correction amount ISCVAFC at the start of fuel cut to the idle speed control valve opening ISCVAIDL during the idling operation of the internal combustion engine is set as the idle speed control valve opening. By issuing a control command for setting the control valve opening ISCVA to the electronically controlled idle speed control valve provided in the internal combustion engine (ISCVA ← ISCVAIDL + ISCVAFC), it is determined whether or not the idle speed control valve opening ISCVA is increased. Alternatively, when feedback control based on the rotational speed NE of the internal combustion engine is performed, for example, the feedback correction amount included in the throttle opening of the internal combustion engine or the feedback correction amount included in the idle speed control valve opening is operated. The throttle opening or the idle speed control valve opening can be adjusted as described above. For example, with respect to the feedback correction amount TAFB added to the throttle opening TAIDL during the idling operation of the internal combustion engine or the feedback correction amount ISCVAFB added to the idle speed control valve opening ISCVAIDL, the throttle opening correction amount accompanying the start of fuel cut A correction amount ISCVAFC for TAFC or idle speed control valve opening may be added (TAFB ← TAFB + TAFC or ISCVAFB ← ISCVAFB + ISCVAFC).

  In the embodiment shown in FIG. 3, as described above, after the determination of whether or not hunting has occurred, control is performed to increase the opening of the throttle or idle speed control valve as the fuel cut starts. However, the execution order of these two determinations may be reversed. That is, it may be determined whether or not hunting has occurred after determining whether or not the control for increasing the opening of the throttle or the idle speed control valve is performed with the start of fuel cut. Further, in a control device for an internal combustion engine in which the control for increasing the opening degree of the throttle or the idle speed control valve is always executed when the fuel cut is started, the opening degree of the throttle or the idle speed control valve is set when the fuel cut is started. The step of determining whether or not the control to increase is performed (step S302 in FIG. 3) may be omitted.

  When it is determined in step S302 that the control for increasing the opening of the throttle or the idle speed control valve is not performed with the start of the fuel cut (step S302: No), the throttle or the idle speed control associated with the start of the fuel cut. Since it is considered that the increase in the opening of the valve is not included in the factor causing the hunting, normal control is executed in the next step S304. That is, when it is determined in step S302 that the control for increasing the opening of the throttle or the idle speed control valve is not performed with the start of the fuel cut (step S302: No), the throttle or the idle speed control valve is opened. There is no control to forcibly decrease the degree. As a result, the opening of the throttle or idle speed control valve when hunting due to other factors has occurred that is not caused by increasing the opening of the throttle or idle speed control valve at the start of fuel cut. It is possible to avoid a situation in which hunting is not suppressed due to a decrease in the hunting.

  On the other hand, if it is determined in step S302 that the control for increasing the opening of the throttle or the idle speed control valve is performed with the start of the fuel cut (step S302: Yes), for example, the throttle associated with the start of the fuel cut. The opening of the throttle or idle speed control valve is reduced by changing the correction amount TAFC of the opening or the correction amount ISCVAFC of the idle speed control valve opening to a lower value, and the throttle or idle speed control as described above. The fuel cut is completed with the valve opening still increased, the fuel supply is resumed with a large amount of air or air-fuel mixture flowing into the internal combustion engine, and the internal combustion engine speed increases. The original target times during idle operation (self-sustaining operation) Hunting between the start of the fuel cut and the end of the fuel cut (return to self-sustained operation) by continuing to reach the fuel cut speed again and restarting the fuel cut. Suppress. Thereby, for example, problems such as deterioration of drivability and deterioration of the exhaust gas purification catalyst can be reduced.

  As described above, when the opening degree of the throttle or the idle speed control valve is decreased as described above, the opening degree of the throttle or the idle speed control valve is increased after the control command for starting the fuel cut is issued. The opening degree of the throttle or the idle speed control valve may be reduced at a stroke until the opening degree before being opened, or the opening degree of the throttle or the idle speed control valve may be gradually reduced. Further, when the opening degree of the throttle or idle speed control valve is reduced as described above, a lower limit value may be provided for the opening degree of the throttle or idle speed control valve.

  Specifically, when the opening of the throttle or idle speed control valve is decreased as described above, before the opening of the throttle or idle speed control valve is increased after there is a control command to start fuel cut. When the opening of the throttle or the idle speed control valve is reduced at a stroke to the opening of the throttle, for example, as described above, the correction amount TAFC of the throttle opening accompanying the start of the fuel cut or the opening of the idle speed control valve By changing the correction amount ISCVAFC to 0 (zero), the opening degree of the throttle or the idle speed control valve can be reduced at a stretch. As a result, for example, when hunting occurs between the start of fuel cut and the return to independent operation, the opening of the throttle is quickly reduced, and the hunting is quickly suppressed, and the rotation of the internal combustion engine The number can be quickly brought close to the target rotational speed.

  Further, when the opening of the throttle or idle speed control valve is decreased as described above, when the opening of the throttle or idle speed control valve is gradually decreased, for example, as described above, the start of fuel cut By gradually reducing the throttle opening correction amount TAFC or the idle speed control valve opening correction amount ISCVAFC by a predetermined amount (decrease amount), the throttle or idle speed control valve opening is gradually reduced. be able to. The predetermined amount may be, for example, a predetermined fixed value, or the throttle opening correction amount TAFC or the idle speed control valve opening correction amount ISCVAFC, the fuel at the start of the fuel cut. Rotational speed of the internal combustion engine at the time when there is a control command to start cutting, target rotational speed of the internal combustion engine at the time when there is a control command to start fuel cutting (the internal combustion engine is mounted on a hybrid vehicle (HV)) Or the set value set for the internal combustion engine, such as the fuel cut speed, the idle speed (return speed), or the like. It may be a variation value that varies accordingly.

  The predetermined amount is, for example, as shown in FIG. 4, the throttle opening correction amount TAFC or the idle speed control valve opening correction amount ISCVAFC or the internal combustion engine speed and target rotation as shown in FIG. It may be a value set so as to decrease as the deviation from the number increases. Advantages of setting the predetermined amount in this way include, for example, that it is possible to suppress the internal combustion engine from being blown up when the fuel cut is performed and the vehicle returns to the independent operation. Can do. FIG. 4 shows the throttle opening correction amount TAFC or the idle speed control valve opening correction amount ISCVAFC and the throttle or idle speed control valve opening reduction amount (as described above). That is, it is a schematic graph showing the relationship between the throttle opening correction amount TAFC or the idle speed control valve opening correction amount ISCVAFC reduction amount associated with the start of fuel cut.

  Alternatively, the predetermined amount is, for example, conversely to the above, the throttle opening correction amount TAFC or the idle speed control valve opening correction amount ISCVAFC or the internal combustion engine speed and target at the start of fuel cut. The value may be set so as to increase as the deviation from the rotational speed increases. Advantages of setting the predetermined amount in this way include, for example, the ability to more quickly converge hunting between the start of fuel cut and return to independent operation. .

  Further, when a lower limit value is provided for the throttle opening when the throttle opening is reduced as described above, the lower limit TALOW of the throttle opening is, for example, the idling operation of the internal combustion engine as described above. It may be set as a value (TALOW ← TAIDL−ΔTA1) smaller than the throttle opening TAIDL at the time by a predetermined value (ΔTA1). Alternatively, when feedback control based on the rotational speed NE of the internal combustion engine is performed, the predetermined lower limit value TALOW is, for example, from a feedback correction amount TAFB added to the throttle opening degree TAIDL during idling operation of the internal combustion engine. May be set as a value smaller by a predetermined value (ΔTA2) (TALOW ← TAIDL + TAFB−ΔTA2).

  Similarly, when a lower limit value is provided for the opening speed of the idle speed control valve when the opening speed of the idle speed control valve is decreased as described above, the lower limit value ISCVALOW of the opening speed of the idle speed control valve is, for example, As described above, it may be set as a value that is smaller by a predetermined value (ΔISCVA1) than the idle speed control valve opening ISCVAIDL during idling operation of the internal combustion engine (ISCVALOW ← ISCVAIDL−ΔISCVA1). Alternatively, when feedback control based on the rotational speed NE of the internal combustion engine is performed, the predetermined lower limit value ISCVALOW is added to, for example, the idle speed control valve opening ISCVAIDL during idling operation of the internal combustion engine. It may be set as a value smaller than the amount ISCVAFB by a predetermined value (ΔISCVA2) (ISCVALOW ← ISCVAIDL + ISCVAFB−ΔISCVA2).

  As described above, in the control apparatus for an internal combustion engine according to this embodiment, when hunting occurs between the start of the fuel cut and the return to the independent operation, the opening degree of the throttle or the idle speed control valve is reduced. In addition, the opening of the throttle or idle speed control valve can be prevented from being excessively reduced. As a result, the rotational speed of the internal combustion engine decreases due to the fuel cut, and the internal combustion engine should return to idle operation (self-sustained operation). The problem that the idling operation cannot be maintained and the rotation of the internal combustion engine becomes unstable can be suppressed.

  Although several embodiments having specific configurations have been described above for the purpose of illustrating the present invention, the scope of the present invention is not limited to these exemplary embodiments, and patents Needless to say, modifications can be made as appropriate within the scope of the claims and the description of the specification.

Claims (8)

A control device for an internal combustion engine having a throttle capable of controlling the opening degree irrespective of an accelerator pedal, wherein the opening degree of the throttle is changed when a fuel cut during operation of the internal combustion engine is started. In the control device for an internal combustion engine that increases the throttle opening after the control command to start
When the start and end of fuel cut are repeated more than a predetermined number of times within a predetermined period after the time when there is a control command to start fuel cut, the throttle opening is decreased. A control device for an internal combustion engine. A control device for an internal combustion engine according to claim 1,
There is a control command to start a fuel cut when the start and end of the fuel cut are repeated a predetermined number of times within a predetermined period after the time when there is a control command to start the fuel cut. A control apparatus for an internal combustion engine, wherein the throttle opening is decreased by an amount corresponding to an increase in the throttle opening increased after the fuel cut is actually started. A control device for an internal combustion engine according to claim 1,
When the start and end of the fuel cut are repeated a predetermined number of times within a predetermined period after the time when there is a control command to start the fuel cut, the throttle is opened by a predetermined amount. A control device for an internal combustion engine, which reduces the degree. A control device for an internal combustion engine according to any one of claims 1 to 3,
When the start and end of the fuel cut are repeated a predetermined number of times within a predetermined period after the time when there is a control command to start the fuel cut, the above is less than a predetermined lower limit value. A control device for an internal combustion engine that does not decrease the opening of the throttle. Control device for an internal combustion engine having an idle speed control valve capable of controlling the opening degree regardless of the accelerator pedal, and changing the opening degree of the idle speed control valve when fuel cut is started during operation of the internal combustion engine In the control device for an internal combustion engine that increases the opening of the idle speed control valve after there is a control command to start fuel cut,
Decrease the opening of the idle speed control valve when the start and end of fuel cut is repeated more than a predetermined number of times within a predetermined period after the time when there is a control command to start fuel cut A control device for an internal combustion engine. A control device for an internal combustion engine according to claim 5,
There is a control command to start a fuel cut when the start and end of the fuel cut are repeated a predetermined number of times within a predetermined period after the time when there is a control command to start the fuel cut. An internal combustion engine in which the opening of the idle speed control valve is decreased by an amount corresponding to an increase in the opening of the idle speed control valve that is increased after the actual fuel cut is started. Control device. A control device for an internal combustion engine according to claim 5,
When the start and end of the fuel cut are repeated a predetermined number of times within a predetermined period after the time when there is a control command to start the fuel cut, the idle speed control is performed by a predetermined amount. A control device for an internal combustion engine that reduces the opening of a valve. A control device for an internal combustion engine according to any one of claims 5 to 7,
When the start and end of the fuel cut are repeated a predetermined number of times within a predetermined period after the time when there is a control command to start the fuel cut, the above is less than a predetermined lower limit value. A control device for an internal combustion engine that does not decrease the opening of the idle speed control valve.

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