JP2006138279A - Secondary air supply system control device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To increase the execution frequency of abnormality diagnosis while securing accuracy in the abnormality diagnosis of a secondary air supply system. <P>SOLUTION: In making the abnormality diagnosis of the secondary air supply system 30 by turning on an air pump 31 to supply secondary air into an exhaust manifold 34, the variation of an engine control parameter (an exhaust pressure fluctuation factor parameter) which is the fluctuation factor of exhaust pressure, is limited. The exhaust pressure fluctuation factor parameter in this case is throttle opening, variable valve timing, ignition timing, or the like. As a method of limiting the variation of the exhaust pressure fluctuation factor parameter, the change speed of the exhaust pressure fluctuation factor parameter may be made slower than normal, or the variation of the exhaust pressure fluctuation factor parameter may be forbidden. The abnormality diagnosis of the secondary air supply system 30 can thereby be carried out in a stable exhaust pressure state. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a secondary air supply system control device for an internal combustion engine that supplies secondary air upstream of an exhaust gas purification catalyst in an exhaust passage of the internal combustion engine.

  For example, as shown in Patent Document 1 (Japanese Patent Laid-Open No. 2003-83048) and Patent Document 2 (Japanese Patent Laid-Open No. 2004-11585), the exhaust gas purification catalyst in the exhaust pipe of the internal combustion engine is upstream of the exhaust gas. In addition, there is known a technique in which secondary air is supplied by an air pump to promote purification (oxidation reaction) of HC and CO in exhaust gas, or to accelerate catalyst warm-up by the reaction heat.

When such a secondary air supply system breaks down, exhaust emission deteriorates. Therefore, in Patent Documents 1 and 2, a pressure sensor is installed in the secondary air supply pipe, and the pressure of the secondary air detected by this pressure sensor is reduced. Based on this, the abnormality diagnosis of the secondary air supply system is performed.
JP 2003-83048 A JP 2004-11585 A

  By the way, since the exhaust pressure acts on the outlet side of the secondary air supply pipe, if the exhaust pressure fluctuates even if the discharge pressure (pump rotational speed) of the air pump is constant, the amount of secondary air supplied into the exhaust pipe will be reduced. Change. For this reason, if the exhaust pressure fluctuates during the supply of secondary air, the amount of secondary air supply will increase or decrease from the required value, and the effect of promoting exhaust gas purification and catalyst warm-up by secondary air supply Will fall. Moreover, since the pressure of the secondary air detected by the pressure sensor in the secondary air supply pipe changes due to the influence of the exhaust pressure, the normal / abnormality of the secondary air supply system diagnosed using the detected pressure of this pressure sensor There is also a possibility that the determination is erroneously determined by fluctuations in exhaust pressure.

  As countermeasures, it has been proposed to stop the supply of secondary air or to stop the abnormality diagnosis of the secondary air supply system when an engine load fluctuation in which the exhaust pressure changes significantly occurs.

  However, if the secondary air supply or abnormality diagnosis is stopped, the exhaust gas purification rate decreases or the frequency of abnormality diagnosis decreases, so even if an abnormality in the secondary air supply system actually occurs, The detection time may be delayed.

  The present invention has been made in view of such circumstances. Therefore, the object of the present invention is to promote exhaust gas purification / catalyst warm-up by secondary air supply and / or frequency of performing abnormality diagnosis of the secondary air supply system. An object of the present invention is to provide a secondary air supply system control device for an internal combustion engine capable of realizing an increase.

  In order to achieve the above-mentioned object, the invention according to claim 1 detects the secondary air information by detecting information on the flow rate or pressure of the secondary air (hereinafter referred to as “secondary air information”) and detecting the secondary air. An engine control parameter that causes exhaust pressure fluctuation during a secondary air supply and / or during a secondary air supply system abnormality diagnosis in a system that performs abnormality diagnosis of the secondary air supply system based on air information using an abnormality diagnosis means (Hereinafter referred to as “exhaust pressure fluctuation factor parameter”) is limited by the limiting means. In this way, fluctuations in the exhaust pressure are suppressed during secondary air supply and / or during secondary air supply system abnormality diagnosis, so secondary air can be supplied as required and promote exhaust gas purification.・ It is possible to enhance the effect of catalyst warm-up promotion and to perform abnormality diagnosis of the secondary air supply system in a stable exhaust pressure state. It is possible to increase the frequency of performing abnormality diagnosis while ensuring accuracy.

  In this case, as means for limiting the change in the exhaust pressure fluctuation factor parameter, the change rate of the exhaust pressure fluctuation factor parameter is made slower than usual as in claim 2, or the exhaust pressure change factor parameter as in claim 3. You may make it prohibit the change of a pressure fluctuation factor parameter. In any of these cases, the change of the exhaust pressure fluctuation factor parameter can be surely limited, and the fluctuation of the exhaust pressure can be surely reduced.

  Further, as described in claim 4, when there is an output increase request from the driver during a period in which the change in the exhaust pressure fluctuation factor parameter is restricted, the restriction on the change in the exhaust pressure fluctuation factor parameter may be released. In this way, even when the change in the exhaust pressure fluctuation factor parameter is limited, when the driver requests acceleration, the output of the internal combustion engine can be increased immediately in response to the acceleration request. Responsiveness can be secured.

  In this case, as described in claim 5, after the change restriction of the exhaust pressure fluctuation factor parameter is canceled by the output increase request from the driver during the operation of the internal combustion engine, the exhaust pressure fluctuation factor parameter of the internal combustion engine is operated. It may be prohibited to return to the change restriction. In short, if there is a request to increase the output from the driver, the change control of the exhaust pressure fluctuation factor parameter is canceled and the vehicle starts or accelerates. If it is prohibited to return to, the exhaust pressure fluctuation parameter such as the intake air amount can be changed with good response in response to the driver's accelerator operation immediately, and drivability can be improved.

  Further, in consideration of the fact that the secondary air supply system is provided with a control valve for opening and closing the secondary air supply passage for supplying the secondary air into the exhaust passage, The change of the exhaust pressure fluctuation factor parameter may be limited during the valve opening period. That is, while the control valve is closed, the supply of the secondary air into the exhaust passage is stopped, and the exhaust passage and the secondary air supply passage are shut off by the control valve, so that the exhaust pressure varies. Since the pressure in the secondary air supply passage (detected value of the secondary air information detection means) is not affected by the exhaust pressure, it is not necessary to limit the fluctuation of the exhaust pressure (change in the exhaust pressure fluctuation factor parameter). Therefore, even during the abnormality diagnosis of the secondary air supply system, the change of the exhaust pressure fluctuation factor parameter may be limited only during the valve opening period of the control valve. It is not necessary to limit the change of the pressure fluctuation factor parameter. Thereby, the period which restrict | limits the change of an exhaust pressure fluctuation factor parameter can be shortened, and drivability can be improved.

  Further, as in claim 7, the exhaust pressure fluctuation factor parameter may be at least one of throttle opening, variable valve timing, ignition timing, and the like. The throttle opening, variable valve timing, ignition timing, and the like affect the exhaust pressure by controlling those parameters and affect the abnormality diagnosis of the secondary air supply system. For this reason, by restricting the change of the exhaust pressure fluctuation factor parameter, the diagnosis state at the time of abnormality diagnosis can be stabilized and the diagnosis can be performed with high accuracy.

Hereinafter, an embodiment embodying the best mode for carrying out the present invention will be described.
First, a schematic configuration of the entire engine control system will be described with reference to FIG. An air cleaner 13 is provided at the most upstream portion of the intake pipe 12 of the engine 11 that is an internal combustion engine, and an air flow meter 14 that detects the intake air amount is provided downstream of the air cleaner 13. On the downstream side of the air flow meter 14, a throttle valve 16 whose opening is adjusted by a motor 15 such as a DC motor, and a throttle opening sensor 17 for detecting the throttle opening are provided.

  Further, a surge tank 18 is provided on the downstream side of the throttle valve 16, and an intake pipe pressure sensor 19 for detecting the intake pipe pressure is provided in the surge tank 18. The surge tank 18 is provided with an intake manifold 20 for introducing air into each cylinder of the engine 11, and a fuel injection valve 21 for injecting fuel is attached in the vicinity of the intake port of the intake manifold 20 of each cylinder. Yes. A spark plug 22 is attached to the cylinder head of the engine 11 for each cylinder.

  In addition, the cylinder block of the engine 11 includes a coolant temperature sensor 23 that detects the coolant temperature, and a crank angle that outputs a rotation angle signal pulse every time the crankshaft of the engine 11 rotates by a predetermined crank angle (for example, 30 ° C. A). A sensor 24 is attached. Based on the output signal pulse of the crank angle sensor 24, the crank angle and the engine speed are detected.

  On the other hand, the exhaust pipe 25 (exhaust passage) of the engine 11 is provided with a catalyst 26 such as a three-way catalyst for purifying CO, HC, NOx, etc. in the exhaust gas. Exhaust gas sensors 27 and 28 (air-fuel ratio sensor, oxygen sensor, etc.) for detecting the air-fuel ratio or rich / lean of the exhaust gas are provided.

  Next, the configuration of the secondary air supply system 30 that supplies secondary air to the upstream side of the catalyst 26 in the exhaust pipe 25 will be described. The secondary air supply system 30 discharges secondary air discharged from an air pump 31 driven by an electric motor through a discharge pipe 32 (secondary air supply passage) to a secondary air supply nozzle 33 (secondary air supply passage) of each cylinder. To the exhaust manifold 34 (exhaust passage) of each cylinder. The discharge pipe 32 of the air pump 31 is provided with a control valve 35 (electromagnetic valve) that opens and closes the discharge pipe 32, and secondary air information is provided between the control valve 35 of the discharge pipe 32 and the air pump 31. A pressure sensor 36 (secondary air information detection means) is provided as detection means.

  The air pump 31 and the control valve 35 of the secondary air supply system 30 are controlled by an engine control circuit (hereinafter referred to as “ECU”) 37. The ECU 37 reads the output signals of various sensors (for example, the crank angle sensor 24, the intake pipe pressure sensor 19, the water temperature sensor 23, etc.) that detect the engine operating state, detects the engine operating state, and according to the engine operating state. The fuel injection amount and ignition timing of each cylinder are controlled.

  Further, the ECU 37 controls a secondary air supply operation by the secondary air supply system 30 by executing a secondary air supply control routine of FIGS. 2 and 3 to be described later, and also performs the secondary air supply of FIG. 4 to be described later. By executing the secondary air supply system abnormality diagnosis routine, it functions as abnormality diagnosis means for determining normality / abnormality of the secondary air supply system 30.

  Here, the abnormality diagnosis method of the secondary air supply system 30 of a present Example is demonstrated using the time chart of FIG. In this embodiment, the secondary air supply by the secondary air supply system 30 is mainly performed during the early catalyst warm-up control immediately after the engine is started, and the driver turns on the ignition switch (time t1). ) Immediately after starting the engine 11 (time t2), the air pump 31 is operated (ON), the control valve 35 is opened, and the supply of secondary air is started.

  At a time t3 when a predetermined time has elapsed from the start of the operation (ON) of the air pump 31, the control valve 35 is closed and the supply of secondary air into the exhaust manifold 34 is stopped. In order to diagnose an abnormality in the supply system 30, the air pump 31 is continuously operated for a predetermined time. In the following description, a period (t2 to t3) from the start of operation of the air pump 31 to the closing of the control valve 35 is referred to as a “first detection period”, and thereafter a period until the operation of the air pump 31 is stopped ( t3 to t4) is called a "second detection period".

  The ECU 37 detects the secondary air pressure in the discharge pipe 32 of the air pump 31 with the pressure sensor 36 at a predetermined sampling period during the first detection period (t2 to t3), and the secondary of the first detection period. The air pressure Ps (average value or annealing value) is calculated. Thereafter, during the second detection period (t3 to t4), the secondary air pressure in the discharge pipe 32 of the air pump 31 is detected by the pressure sensor 36 at a predetermined sampling period, and the secondary air in the second detection period is detected. The pressure Po (average value or annealing value) is obtained. Thereafter, a pressure difference (Po-Ps) between the secondary air pressure Po in the second detection period and the secondary air pressure Ps in the first detection period is calculated, and the pressure difference (Po-Ps) is equal to or greater than a determination value. Whether the secondary air supply system 30 is normal or abnormal is determined based on whether or not

  By the way, since the exhaust pressure acts on the outlet side of the secondary air supply nozzle 33, if the exhaust pressure fluctuates even if the discharge pressure (pump rotational speed) of the air pump 31 is constant, the secondary pressure into the exhaust manifold 34 is obtained. Air supply changes. For this reason, if the exhaust pressure fluctuates during the supply of secondary air, the amount of secondary air supply will increase or decrease from the required value, and the effect of promoting exhaust gas purification and catalyst warm-up by secondary air supply Will fall. Moreover, since the secondary air pressure detected by the pressure sensor 36 of the discharge pipe 32 changes depending on the exhaust pressure, the normal / abnormal determination of the secondary air supply system 30 diagnosed using the detected pressure of the pressure sensor 36 is exhausted. There is a possibility of erroneous determination due to pressure fluctuation.

  Therefore, in the present embodiment, changes in engine control parameters (hereinafter referred to as “exhaust pressure fluctuation factor parameters”) that become exhaust pressure fluctuation factors during secondary air supply and during abnormality diagnosis of the secondary air supply system 30 are limited. I have to. Here, the exhaust pressure fluctuation factor parameter is, for example, throttle opening, variable valve timing, ignition timing, and the like. As a method for limiting the change in the exhaust pressure fluctuation factor parameter, for example, the change speed of the exhaust pressure fluctuation factor parameter may be slower than usual, or the change in the exhaust pressure fluctuation factor parameter may be prohibited.

  Further, when the required acceleration exceeds a predetermined value due to an output increase request from the driver during the supply of secondary air, the air pump 31 is stopped and the control valve 35 is closed to stop the supply of secondary air. Then, the change restriction of the exhaust pressure fluctuation factor parameter is released, and the normal engine control is resumed. After this, even if the secondary air supply execution condition is satisfied, the return to the exhaust pressure fluctuation factor parameter change restriction is prohibited, and the exhaust pressure fluctuation factor parameter changes until the engine 11 is stopped. The restriction is released.

  The control of the secondary air supply system 30 of the present embodiment described above is executed by the ECU 37 in accordance with the secondary air supply control routine of FIGS. This routine is periodically executed during the ON period of the ignition switch. When this routine is started, first, at step 101, it is determined whether or not the rapid acceleration request flag is “0”. This sudden acceleration request flag is a flag for confirming whether or not a sudden acceleration request (requested acceleration greater than a predetermined value) has occurred during the supply of secondary air. When a sudden acceleration request has occurred during the supply of secondary air The rapid acceleration request flag is set to “1” (step 105), and if the rapid acceleration request is not generated during the secondary air supply, the rapid acceleration request flag is maintained at “0”.

  If it is determined in step 101 that the rapid acceleration request flag = 1 (there is a rapid acceleration request), this routine is terminated without performing the subsequent processing. As a result, the change restriction of the secondary air supply and the exhaust pressure fluctuation factor parameter is stopped at the stage where the rapid acceleration request is generated during the supply of the secondary air. After this, even if the secondary air supply execution condition is satisfied, it is prohibited to return to the change restriction of the secondary air supply and the exhaust pressure fluctuation factor parameter, and the secondary air supply is stopped until the engine 11 is stopped. The change restriction of the air supply and exhaust pressure fluctuation factor parameters is maintained in a stopped state.

  On the other hand, if it is determined in step 101 that the rapid acceleration request flag = 0 (no rapid acceleration request), the process proceeds to step 102 to determine whether or not the secondary air supply execution condition is satisfied. Determine by (1) to (3).

(1) Secondary air supply is not complete
(2) The cooling water temperature detected by the water temperature sensor 23 is within a predetermined range.
(3) The engine speed is within the range of the idle region. If all of these conditions (1) to (3) are satisfied, the secondary air supply execution condition is satisfied, but none of the conditions is satisfied. If there is, the secondary air supply execution condition is not satisfied, and this routine is terminated without performing the subsequent processing.

  On the other hand, if all of the above conditions (1) to (3) are satisfied and the secondary air supply execution condition is satisfied, the process proceeds to step 103, where the required acceleration is calculated based on the accelerator operation amount and the like. Thus, it is determined whether the requested acceleration is equal to or less than a predetermined value (no sudden acceleration request). As a result, if it is determined that the required acceleration is equal to or less than a predetermined value (no rapid acceleration request), the process proceeds to step 111 in FIG. 3 to determine whether or not it is the first detection period (t2 to t3). If this is the detection period, the routine proceeds to step 112 where the change of the engine control parameter (exhaust pressure fluctuation factor parameter) that becomes the exhaust pressure fluctuation factor is limited. Here, the exhaust pressure fluctuation factor parameter is, for example, throttle opening, variable valve timing, ignition timing, and the like. As a method for limiting the change in the exhaust pressure fluctuation factor parameter, for example, the change speed of the exhaust pressure fluctuation factor parameter may be slower than usual, or the change in the exhaust pressure fluctuation factor parameter may be prohibited. The processing in step 112 serves as a limiting means in the claims.

  During the first detection period, the control valve 35 is opened (step 113), the air pump 31 is turned on (step 114), and secondary air is supplied into the exhaust manifold 34. Furthermore, during the first detection period, in step 115, a secondary air pressure Ps calculation routine (not shown) for the first detection period is executed to obtain the secondary air pressure Ps (average) for the first detection period. Value or annealing value). Specifically, the secondary air pressure detected by the pressure sensor 36 during the first detection period is integrated, and the integrated value is divided by the number of integrations to average the secondary air pressure Ps during the first detection period. Or the secondary air pressure detected by the pressure sensor 36 during the first detection period is smoothed to determine the smoothing value of the secondary air pressure Ps during the first detection period.

  After the end of the first detection period, it is determined as “No” in step 111, and the process proceeds to step 116 to determine whether or not it is the second detection period (t3 to t4). During the second detection period, the routine proceeds to step 117, where the control valve 35 is closed and the supply of the secondary air into the exhaust manifold 34 is shut off. Thereafter, the abnormality diagnosis of the secondary air supply system 30 is performed. Therefore, the air pump 31 is continuously operated (ON). Furthermore, during the second detection period, in step 118, a secondary air pressure Po calculation routine (not shown) for the second detection period is executed to obtain the secondary air pressure Po (average) for the second detection period. Value or annealing value). During this second detection period, the control valve 35 is closed, and the exhaust pressure does not affect the detected value of the pressure sensor 36. Therefore, the change restriction of the exhaust pressure fluctuation factor parameter is released, and normal engine control is restored. .

  Thereafter, when the second detection period is over, it is determined as “No” in Step 116, and the process proceeds to Step 119, where a secondary air supply system abnormality diagnosis routine of FIG. After determining whether the air supply system 30 is normal or abnormal, the routine proceeds to step 120, where the air pump 31 is turned off and the routine is terminated.

  On the other hand, when it is determined that the required acceleration is larger than the predetermined value (there is a sudden acceleration request) during the secondary air supply (when the air pump 31 is ON) in step 104 of FIG. The acceleration request flag is set to “1”, the process proceeds to step 106, the control valve 35 is closed, the supply of secondary air into the exhaust manifold 34 is stopped, and the air pump 31 is stopped in the next step 107. (OFF) to stop the abnormality diagnosis and stop the change restriction of the exhaust pressure fluctuation factor parameter. Once the rapid acceleration request flag is set to “1”, the rapid acceleration request flag is maintained at “1” until the engine 11 is stopped, so that the secondary air supply execution condition is satisfied. Even so, it is prohibited to return to the change restriction of the secondary air supply and exhaust pressure fluctuation factor parameter, and the change restriction of the secondary air supply and exhaust pressure fluctuation factor parameter is suspended until the engine 11 is stopped. Maintained in a state. The rapid acceleration request flag is reset to “0” by the initialization process at the time of engine start.

  When the secondary air supply system abnormality diagnosis routine of FIG. 4 is started in step 119 of FIG. 3, first, in step 201, the secondary air pressure Po in the second detection period and the secondary air in the first detection period. The pressure difference (Po−Ps) with respect to the pressure Pa is compared with a determination value. If the pressure difference (Po−Ps) is larger than the determination value, the process proceeds to step 202 and the secondary air supply system 30 is normal. Determination is made and this routine is terminated.

  On the other hand, if it is determined in step 201 that the pressure difference (Po−Ps) is equal to or smaller than the determination value, the process proceeds to step 203, where it is determined that the secondary air supply system 30 is abnormal, and the next step 204. Then, a warning lamp (not shown) is turned on or blinked, or a warning is displayed on the display unit of the instrument panel of the driver's seat. At the next step 205, abnormal information such as an abnormal code is backed up by the ECU 37. The program is stored in a rewritable nonvolatile memory such as a RAM, and this routine is terminated.

  According to the present embodiment described above, the change in the engine control parameter (exhaust pressure fluctuation factor parameter) that becomes the exhaust pressure fluctuation factor is limited during the secondary air supply (during the abnormality diagnosis of the secondary air supply system 30). As a result, during the secondary air supply (during the abnormality diagnosis of the secondary air supply system 30), the fluctuation of the exhaust pressure can be suppressed and the secondary air can be supplied as required to promote the exhaust gas purification / catalyst. The effect of promoting warm-up can be enhanced, and the abnormality diagnosis of the secondary air supply system 30 can be performed in a stable exhaust pressure state, whereby the abnormality diagnosis of the secondary air supply system 30 can be performed. It is possible to increase the frequency of performing abnormality diagnosis while ensuring accuracy.

  In addition, in this embodiment, when there is a sudden acceleration request (output increase request) from the driver during a period during which the change in the exhaust pressure fluctuation factor parameter is limited (during secondary air supply), the change in the exhaust pressure fluctuation factor parameter Since the restriction is released, even if the exhaust pressure fluctuation factor parameter change is restricted, the engine output can be increased immediately in response to a driver's sudden acceleration request. Acceleration responsiveness can be secured.

  By the way, even in the abnormality diagnosis period (t2 to t4) of the secondary air supply system 30, the supply of secondary air into the exhaust manifold 34 is stopped during the valve closing period (t3 to t4) of the control valve 35. In addition, the exhaust manifold 34 and the discharge pipe 32 of the air pump 31 are shut off by the control valve 35, and even if the exhaust pressure fluctuates, the pressure in the discharge pipe 32 of the air pump 31 (the detection value of the pressure sensor 36) is the exhaust pressure. Since it is not affected, it is not necessary to limit the fluctuation of the exhaust pressure (change of the exhaust pressure fluctuation factor parameter).

  Considering this point, in this embodiment, even during the abnormality diagnosis period of the secondary air supply system 30, the change in the exhaust pressure fluctuation factor parameter is changed only during the valve opening period (t2 to t3) of the control valve 35. Since the restriction on the change of the exhaust pressure fluctuation factor parameter is released during the valve closing period (t3 to t4) of the control valve 35, the period for restricting the change of the exhaust pressure fluctuation factor parameter can be shortened. There is an advantage that drivability can be improved.

  However, according to the present invention, the change of the exhaust pressure fluctuation factor parameter may be limited also during the valve closing period (t3 to t4) of the control valve 35 in the abnormality diagnosis period of the secondary air supply system 30. Needless to say.

  Further, even when abnormality diagnosis (secondary air pressure detection) of the secondary air supply system 30 is not performed during the supply of secondary air, the change in the exhaust pressure fluctuation factor parameter may be limited.

  In this embodiment, as the secondary air information, the secondary air pressure is detected by the pressure sensor 36, but the flow rate of the secondary air discharged from the air pump 31 may be detected.

  In addition, the present invention can be implemented with various modifications such that the abnormality diagnosis method of the secondary air supply system 30 may be appropriately changed.

1 is a diagram illustrating an overall configuration of an engine control system according to an embodiment of the present invention. It is a flowchart explaining the flow of a process of a secondary air supply control routine (the 1). It is a flowchart explaining the flow of a process of a secondary air supply control routine (the 2). It is a flowchart explaining the flow of a process of a secondary air supply system abnormality diagnosis routine. It is a time chart explaining an example of abnormality diagnosis processing.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 11 ... Engine (internal combustion engine), 12 ... Intake pipe, 25 ... Exhaust pipe (exhaust passage), 26 ... Catalyst, 30 ... Secondary air supply system, 31 ... Air pump, 32 ... Discharge pipe (secondary air supply passage), 33 ... Secondary air supply nozzle (secondary air supply passage), 34 ... Exhaust manifold (exhaust passage), 35 ... Control valve, 36 ... Pressure sensor (secondary air information detection means), 37 ... ECU (abnormality diagnosis means, Restriction means)

Claims (7)

In the secondary air supply system control device for an internal combustion engine that supplies secondary air to the upstream side of the exhaust gas purification catalyst in the exhaust passage of the internal combustion engine,
Secondary air information detection means for detecting information on the flow rate or pressure of secondary air (hereinafter referred to as “secondary air information”);
An abnormality diagnosis means for performing an abnormality diagnosis of the secondary air supply system based on the secondary air information detected by the secondary air information detection means;
Limiting means for limiting a change in engine control parameter (hereinafter referred to as “exhaust pressure fluctuation factor parameter”) that becomes an exhaust pressure fluctuation factor during secondary air supply and / or abnormality diagnosis of the secondary air supply system. A control device for a secondary air supply system for an internal combustion engine.   The secondary air supply for an internal combustion engine according to claim 1, wherein the limiting means limits the change in the exhaust pressure fluctuation factor parameter by making the change speed of the exhaust pressure fluctuation factor parameter slower than usual. System controller.   2. The secondary air supply system control device for an internal combustion engine according to claim 1, wherein the limiting unit limits the change of the exhaust pressure fluctuation factor parameter by prohibiting the change of the exhaust pressure fluctuation factor parameter. .   The limiting means includes means for canceling the change restriction of the exhaust pressure fluctuation factor parameter when the driver requests an output increase during a period of restricting the change of the exhaust pressure fluctuation factor parameter. The secondary air supply system control device for an internal combustion engine according to any one of claims 1 to 3.   The restricting means limits the change of the exhaust pressure fluctuation factor parameter during the operation of the internal combustion engine after the change restriction of the exhaust pressure fluctuation factor parameter is released by an output increase request from the driver during the operation of the internal combustion engine. The secondary air supply system control device for an internal combustion engine according to any one of claims 1 to 4, wherein the return is prohibited. The secondary air supply system includes a control valve that opens and closes a secondary air supply passage for supplying secondary air into the exhaust passage,
The secondary air supply system control for an internal combustion engine according to any one of claims 1 to 5, wherein the restricting means restricts a change in the exhaust pressure fluctuation factor parameter during a valve opening period of the control valve. apparatus.   The internal combustion engine according to any one of claims 1 to 6, wherein the exhaust pressure fluctuation factor parameter is at least one of throttle opening, variable valve timing, ignition timing, and the like. Secondary air supply system controller.

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