JP5220583B2 - Control device for internal combustion engine - Google Patents

Description

  The present invention relates to a control device for an internal combustion engine, and more particularly to a control device for an internal combustion engine provided with an idle speed control valve provided in a bypass passage that bypasses a throttle valve in an intake passage.

  Conventionally, when the throttle valve of the intake passage is near the fully closed position (that is, at the time of engine start or idling operation), the idling speed control disposed in the bypass passage that connects the upstream side and the downstream side of the throttle valve 2. Description of the Related Art A control device for an internal combustion engine that adjusts the idle speed of the internal combustion engine by driving (opening and closing) the valve with a stepping motor is widely known.

In the control device for an internal combustion engine described above, there has also been proposed a technique for detecting (detecting) an abnormality of an idle speed control valve (stepping motor step-out due to valve sticking or the like) (see, for example, Patent Document 1). . In the technique described in Patent Document 1, when the no-load state of the internal combustion engine is detected, the opening degree of the idle speed control valve is feedback controlled so that the speed of the internal combustion engine matches the target idle speed. At the same time, when the rotational speed of the internal combustion engine is not within a predetermined range set according to the target idle rotational speed during the feedback control, it is determined that an abnormality has occurred in the idle rotational speed control valve.
Japanese Patent No. 2836455

  However, as in the technique described in Patent Document 1, if the idle rotation speed control valve abnormality detection is performed when feedback control is executed by detecting the no-load state of the internal combustion engine, there is no internal combustion engine. A device for detecting a load state (for example, a vehicle speed sensor) is required, and the configuration is complicated.

  Accordingly, an object of the present invention is to provide a control device for an internal combustion engine that solves the above-described problems and that can detect an abnormality of an idle speed control valve while having a simple configuration.

In order to achieve the above object, in claim 1, a throttle valve disposed in an intake passage of an internal combustion engine, a bypass passage connected to the intake passage and bypassing the throttle valve, and the bypass passage In the control device for an internal combustion engine, comprising: an idle speed control valve that adjusts an idle speed of the internal combustion engine by adjusting an air amount of the internal combustion engine; and a stepping motor that drives the idle speed control valve. The internal combustion engine is started when the engine is at the idle opening, and after the engine is started, it is determined whether or not the engine is still at the idle opening. A rotation speed range for determining whether or not the rotation speed of the internal combustion engine is within a predetermined range set according to a target idle rotation speed And when the engine speed is determined not to be within the predetermined range, the idle speed is set via the stepping motor so that the speed of the internal combustion engine matches the target idle speed. A feedback control means for feedback-controlling the opening of the control valve; and the idle speed control valve when the speed of the internal combustion engine does not converge within the predetermined range after a predetermined time has elapsed since the feedback control was executed. The idle opening start state determining means has no history that the throttle valve has been driven once from the idle opening, and the number of revolutions of the internal combustion engine. There the internal combustion engine is configured as judged to have been started when a less than complete explosion rotational speed.

  In the control device for an internal combustion engine according to claim 2, temperature detection means for detecting the temperature of the internal combustion engine, and a target for calculating a target step position of the stepping motor based on the detected temperature of the internal combustion engine. The stepping motor when a difference between the rotational speed of the internal combustion engine and the target idle rotational speed is equal to or less than a predetermined value during execution of the feedback control based on the step position calculating means and the detected temperature of the internal combustion engine And a replacement means for replacing the position of the position with the step value of the target step position.

In the control apparatus for an internal combustion engine according to claim 3, with is determined that an abnormality has occurred prior Symbol idle speed control valve, when the rotation speed of the internal combustion engine is equal to or greater than a predetermined rotational speed, the internal combustion engine Rotation speed increase prevention means for controlling at least one of ignition and fuel injection to prevent increase in the rotation speed of the internal combustion engine is provided.

  In the control apparatus for an internal combustion engine according to claim 4, the feedback control means is configured to drive the idle speed control valve for a predetermined number of steps continuously in the opening direction or the closing direction during the execution of the feedback control. In addition, when the amount of change in the rotational speed of the internal combustion engine is less than a predetermined value, the feedback control is stopped.

  In the control apparatus for an internal combustion engine according to claim 5, the feedback control means is configured to restart the feedback control after a predetermined stop time has elapsed since the feedback control was stopped.

In the control apparatus for an internal combustion engine according to claim 1, the internal combustion engine is started when the throttle valve is in the idle opening, there still idle opening even after the start-up, once the idle opening no even driven history, and, when the rotation speed of the internal combustion engine is determined that the internal combustion engine when it is less than complete explosion rotational speed is started, the rotational speed of the internal combustion engine in accordance with the target idle speed It is determined whether or not the engine speed is within the predetermined range, and when it is determined that the engine speed is not within the predetermined range, the engine speed control valve is set so that the engine speed matches the target idle speed. When the engine speed does not converge within a predetermined range after a predetermined time has elapsed, it is determined that an abnormality has occurred in the idle speed control valve. In spite of the simple configuration, specifically, it is possible to detect an abnormality in the idle speed control valve without requiring a device (for example, a vehicle speed sensor) for detecting an unloaded state of the internal combustion engine as in the prior art ( Detection) as well as cost advantages.

  In the control device for an internal combustion engine according to claim 2, the target step position of the stepping motor is calculated based on the temperature of the internal combustion engine, and during execution of feedback control based on the temperature of the internal combustion engine, The position of the stepping motor is replaced with the step value of the target step position when the difference between the rotational speed and the target idle speed is equal to or less than the predetermined value (in other words, when the engine speed converges to the target idle speed). Since it is configured, in addition to the above-described effects, for example, the deviation between the step position recognized by the control device caused by the step-out of the stepping motor and the actual step position of the stepping motor can be corrected. The control accuracy of the valve can be ensured.

  In the control device for an internal combustion engine according to claim 3, when it is determined that an abnormality has occurred in the idle speed control valve, and when the speed of the internal combustion engine exceeds a predetermined speed, ignition and fuel of the internal combustion engine Since at least one of the injections is controlled to prevent an increase in the rotational speed of the internal combustion engine, in addition to the effects described above, the rotational speed of the internal combustion engine when an abnormality occurs in the idle rotational speed control valve Can be effectively prevented from rising (blowing up).

  In the control apparatus for an internal combustion engine according to claim 4, during the execution of the feedback control, the idle speed control valve is continuously driven in the opening direction or the closing direction for a predetermined number of steps, and the speed of the internal combustion engine is determined. Since the feedback control is stopped when the change amount of the engine is less than the predetermined value, the feedback control can be stopped in an operation state in which the feedback control need not be executed in addition to the above-described effect. Stalls can be prevented.

  In the control device for an internal combustion engine according to claim 5, since the feedback control is resumed after a predetermined stop time has elapsed since the feedback control was stopped, the effect described in claim 4 is added. It is possible to resume the feedback control that has been stopped at an effective timing.

  The best mode for carrying out the control apparatus for an internal combustion engine according to the present invention will be described below with reference to the accompanying drawings.

  FIG. 1 is a schematic diagram schematically showing a control apparatus for an internal combustion engine according to an embodiment of the present invention.

  In FIG. 1, reference numeral 10 denotes an internal combustion engine (hereinafter referred to as “engine”) mounted on a vehicle (not shown) (for example, a motorcycle). The engine 10 is a four-cycle single-cylinder water-cooled type and is composed of a gasoline engine having a displacement of about 250 cc. Reference numeral 10a denotes a crankcase of the engine 10.

  A throttle valve 14 is disposed in the intake passage 12 of the engine 10. The throttle valve 14 is mechanically connected to an accelerator (throttle grip) provided in the vehicle so as to be manually operable via a throttle wire (both not shown), and is opened and closed in accordance with the operation amount of the accelerator 10. The intake air is regulated, specifically, the amount of air drawn from the air cleaner 16 and flowing through the intake passage 12 is adjusted. The throttle valve 14 is set to have an idle opening when the accelerator is not operated.

  Connected to the intake passage 12 is a bypass passage 20 that connects the upstream side and the downstream side of the throttle valve 14 to bypass the throttle valve 14. An idle speed control valve (idle speed control valve; hereinafter referred to as “ISC valve”) 22 for adjusting the idle speed of the engine 10 by adjusting the air amount of the bypass path 20 is provided in the middle of the bypass path 20 and is stepping. It is driven by a motor (electric motor, actuator) 24.

  FIG. 2 is an enlarged schematic sectional view showing the vicinity of the ISC valve 22 and the stepping motor 24 shown in FIG.

  As shown in FIG. 2, the stepping motor 24 is coaxially connected to the first and second coils (A-phase and B-phase coils) 24a and 24b, the magnet rotor 24c, and the lower end of the magnet rotor 24c, This is a bipolar two-phase excitation type stepping motor comprising a feed screw 24d having a male screw threaded on its outer peripheral surface and a case 24e for housing first and second coils 24a, 24b and the like.

  The ISC valve 22 is arranged in a valve body (plunger valve) 22a for opening and closing the bypass passage 20 and an internal space of the valve body 22a, and a slide piece formed with a female screw corresponding to the male screw of the feed screw 24d. 22b and a spring 22c inserted between the valve body 22a and the slide piece 22b are integrally attached. As shown in the figure, the stepping motor 24 and the ISC valve 22 are connected by screwing the male screw of the feed screw 24d and the female screw of the slide piece 22b, and the valve body 22a is connected from the case 24e. It is positioned so as to protrude toward the bypass 20.

  Accordingly, in the stepping motor 24, the magnet rotor 24c and the feed screw 24d are rotated by alternately switching the directions of the currents flowing through the first and second coils 24a and 24b, and the rotation direction of the feed screw 24d is rotated. Accordingly, the ISC valve 22 is displaced in the vertical direction in FIG. 2 while the movement in the rotational direction is restricted by the guide 24 f, thereby opening and closing the bypass path 20 and adjusting the amount of air flowing through the bypass path 20.

  Returning to the description of FIG. 1, an injector 26 is disposed near the intake port on the downstream side of the throttle valve 14 in the intake passage 12, and gasoline fuel is injected into the intake air adjusted by the throttle valve 14 and the ISC valve 22. The injected fuel mixes with intake air to form an air-fuel mixture, and the air-fuel mixture flows into the combustion chamber 32 when the intake valve 30 opens.

  The air-fuel mixture flowing into the combustion chamber 32 is ignited by spark discharge from the spark plug 36 with a high voltage supplied from the ignition coil 34 and burns, and the piston 40 is driven downward in FIG. 1 to rotate the crankshaft 42. . The exhaust gas generated by the combustion flows through the exhaust pipe 46 when the exhaust valve 44 is opened. A catalyst device 50 is disposed in the exhaust pipe 46 to remove harmful components in the exhaust gas. The exhaust gas purified by the catalyst device 50 flows further downstream and is discharged to the outside of the engine 10. In addition, a starter motor 52 for starting the engine 10 is connected to the crankshaft 42.

  A throttle opening sensor 54 composed of a potentiometer is provided in the vicinity of the throttle valve 14 to generate an output indicating the opening θTH of the throttle valve 14. An intake air temperature sensor 56 is provided on the upstream side of the throttle valve 14 in the intake passage 12 to generate an output indicating the temperature TA of the intake air, and an absolute pressure sensor 60 is provided on the downstream side to provide an absolute pressure in the intake passage ( Engine load) produces an output indicating PBA.

  A water temperature sensor (temperature detection means) 62 is attached to the cooling water passage 10b of the cylinder block of the engine 10, and an output corresponding to the temperature (engine cooling water temperature) TW of the engine 10 is generated. A crank angle sensor 64 is mounted near the crankshaft 42 of the engine 10 and outputs a crank angle signal at a predetermined crank angle position.

  In addition, an ignition switch 66 and a starter switch 70 are installed at appropriate positions of the vehicle. Although not shown in the figure, the ignition switch 66 has three known positions in order of lock, off, and on, and supplies and shuts off electric power to each electric device according to the position selected by the driver. Specifically, when the lock or off position is selected in the ignition switch 66, all the power supply to each sensor, the stepping motor 24, etc. is cut off, and when the on position is selected, it is mounted on the vehicle. The battery 72 is connected, and power supply to each sensor except the starter motor 52 and the stepping motor 24 is started. When the lock position is selected, a handle (not shown) is fixed (locked).

  The starter switch 70 is connected to the battery 72 to drive the starter motor 52 when operated by the driver, whereby cranking is started and the engine 10 is started.

  The output of each sensor such as the throttle opening sensor 54 is input to an electronic control unit (hereinafter referred to as “ECU”) 74.

  FIG. 3 is a block diagram showing the overall configuration of the ECU 74.

  The ECU 74 is composed of a microcomputer, and as shown in FIG. 3, the A / D conversion receives the output of the waveform shaping circuit 74a to which the output of the crank angle sensor 64 is input, the rotation speed counter 74b, the water temperature sensor 62, and the like. A circuit 74c and a CPU 74d are provided. The ECU 74 further includes an ignition circuit 74e for energizing the ignition coil 34 according to a control signal from the CPU 74d, two drive circuits 74f and 74g for driving the injector 26 and the stepping motor 24, a ROM 74h, a RAM 74i, and a timer 74j. Prepare.

  The waveform shaping circuit 74a shapes the output (signal waveform) of the crank angle sensor 64 into a pulse signal, and outputs it to the rotation speed counter 74b. The rotational speed counter 74b counts the input pulse signal to detect (calculate) the engine rotational speed NE, and outputs a signal indicating the engine rotational speed NE to the CPU 74d. The A / D conversion circuit 74c receives the output of each sensor such as the throttle opening sensor 54, converts the analog signal value into a digital signal value, and outputs it to the CPU 74d.

  The CPU 74d performs an operation according to a program stored in the ROM 74h based on the converted digital signal and the like, sends a control signal to the drive circuit 74g to control energization to the stepping motor 24, and opens the ISC valve 22. The amount of air in the bypass 20 is adjusted by adjusting the degree. Further, the CPU 74d similarly executes a calculation according to a program stored in the ROM 74h based on a digital signal or the like, and sends a control signal to the ignition circuit 74e or each of the drive circuits 74f and 74g to drive the ignition coil 16 and the injector 26. Thus, the ignition timing and the fuel injection amount are controlled.

  The RAM 74i is used for buffering the engine speed NE performed in a program described later, and the timer 74j is also used for time measurement processing in the program.

  FIG. 4 is a flowchart showing the operation of the control apparatus for an internal combustion engine according to this embodiment. The illustrated program is executed (looped) at a predetermined time interval, for example, 20 msec, in the ECU 74 when the ignition switch 66 is turned on.

In the following, in S10, it is first determined whether or not the bit of the ISC abnormality determination flag F_XAPXICSS (described later) is 1. Since flag F_XAPXISCS will be the initial value is 0, the process proceeds to S12 are negated by S10, the engine rotational speed NE detected (calculated) based on the output of the crank angle sensor 64, a throttle opening sensor 54 proceeds to S14 Based on the output, the opening θTH of the throttle valve 14 is detected (calculated).

  Next, in S16, the rotation speed abnormality detection process is executed. Specifically, in S16, whether or not the engine 10 is in a start state in which an abnormality in the engine speed NE can be detected, and in a start state in which the abnormality can be detected, the engine speed NE is within a predetermined range (described later). This is a process for detecting whether or not there is.

  FIG. 5 is a sub-routine flowchart of the rotation speed abnormality detection process.

  First, in S100, it is determined whether or not the engine speed NE is 0. In other words, it is determined whether or not the starter switch 70 is not turned on and before the engine 10 is started. When the result in S100 is affirmative, the routine proceeds from S102 to S108, and the bits of a rotation speed abnormality detection flag F_XOBXISCS, a rotation speed abnormality detection history flag F_XICSRCSR, a throttle opening history flag F_THOPEN, and an idle opening start state flag F_IDLECNT are set to 0, respectively. Set to.

  When the starter switch 70 is turned on in the next program loop and cranking is started, the result of S100 is negative and the program proceeds to S110, in which it is determined whether or not the bit of the rotation speed abnormality detection flag F_XOBXISCS is 1. Since the flag F_XOBXISCS is set to 0 in S102, the determination here is negative and the routine proceeds to S112, where it is determined whether or not the throttle valve 14 is at the idle opening.

  If NO in S112, that is, if the accelerator is operated by the driver and the throttle valve 14 is not at the idle opening, the process proceeds to S114, and the bit of the throttle opening history flag F_THOPEN is set to 1. Therefore, when the bit of the flag F_THOPEN is set to 1, the fact that the accelerator has been operated and the throttle valve 14 has been driven even once in the opening direction from the idle opening degree is set to 0. Means that the throttle valve 14 remains in the idle opening without being operated.

  On the other hand, when the result in S112 is affirmative, the program proceeds to S116, in which it is determined whether or not the bit of the rotation speed abnormality detection history flag F_XICSRCSR is 1. Since the flag F_XICSRCSR is set to 0 in S102, when the process of S116 is executed for the first time, the determination is negative and the process proceeds to S118 to determine whether the bit of the throttle opening history flag F_THOPEN is 1 or not.

  When the result in S118 is negative, the program proceeds to S120, in which it is determined whether the bit of the idle opening start state flag F_IDLECNT is 1. Since the flag F_IDLECNT is set to 0 in S108, the result in S120 is negative and the process proceeds to S122, in which it is determined whether the engine speed NE is equal to or higher than the complete explosion speed NEref (for example, 750 rpm).

  If NO in S122, that is, if the engine speed NE is between 0 and the complete explosion speed NEref, the process proceeds to S124, and the bit of the idle opening start state flag F_IDLECNT is set to 1, while if the result is affirmative, S108. Then, the bit of the flag F_IDLECNT is set to 0.

  When the bit of the flag F_IDLECNT is set to 1 in S124, it is affirmed in S120 in the next program loop and skips S122 and S124. In the next and subsequent program loops, when the accelerator is operated even once and the bit of the throttle opening history flag F_THOPEN is set to 1 (S114), the result in S118 is affirmative and the process proceeds to S108, and the bit of the flag F_IDLECNT is set to 0. set.

  Therefore, setting the idling opening start state flag F_IDLECNT to 1 starts the engine 10 when the throttle valve 14 is at the idling opening (exactly, it is cranked when the engine 10 is stopped). This means that the engine is still in the idling opening after being started, and thus it is in a starting state in which an abnormality of the engine speed NE described later can be detected. Hereinafter, the start state of the engine 10 as described above is also referred to as “idle opening start state”.

  When the engine 10 is in the idling opening start state, the process proceeds to S126, and the engine speed NE is set to a predetermined range set according to the target idle speed NEa (for example, the lower limit value is 1000 rpm and the upper limit value is the target idle speed NEa). It is determined whether or not it is within a range (NEb) set as a rotational speed obtained by adding a predetermined value (500 rpm). The calculation of the target idle speed NEa will be described later.

  Since the engine speed NE when the ISC valve 22 is normal is in the vicinity of the idle speed NEa by open loop control (described later) executed after the engine is started, the result is affirmed in S126 and the subsequent processing is skipped.

  On the other hand, when the result in S126 is negative, the program proceeds to S128, in which it is determined whether or not a first predetermined time Ta has elapsed since the engine speed NE is not within the predetermined range NEb. Specifically, when the determination in S128 is negative in S126, a first predetermined time Ta (for example, 3 sec) is set in an abnormality detection timer (down counter) in a program (not shown), and time measurement is started to detect abnormality. This is done by determining whether the timer value has become zero.

  When the result in S128 is negative, the subsequent processing is skipped. When the result is affirmative, the process proceeds to S130, and the bit of the rotation speed abnormality detection flag F_XOBXISCS is set to 1. That is, when the bit of the flag F_XOBXISCS is set to 1, the engine speed NE continues for the first predetermined time Ta and is not within the predetermined range NEb (rotational speed abnormality), and the ISC valve 22 is abnormal. Means that there is a possibility.

  Next, in S132, it is determined whether or not the engine speed NE is equal to or higher than the target idle speed NEa. That is, S132 is a process for determining whether or not the engine speed NE has exceeded the predetermined range NEb on the high rotation side. When the result in S132 is affirmative, the program proceeds to S134, in which an ISC step position ISCSTEP indicating the step position of the stepping motor 24 recognized by the ECU 74 is set to a value indicating the fully opened position of the ISC valve 22 (fully opened step position, specifically 200 steps). On the other hand, if the result is NO, the process proceeds to S136, and a value indicating the fully closed position of the ISC valve 22 (fully closed step position, specifically 0 step) is set in ISCSTEP.

  That is, in S132 to S136, in order to prepare for the feedback control to be executed later, specifically, to prepare for the operation of driving the ISC valve 22 in the closing direction or the closing direction via the stepping motor 24, the fully opened step is set to the ISC step position ISCSTEP. The position or fully closed step position was temporarily set.

  Further, when the bit of the flag F_XOBXISCS is set to 1 in S130, the result of the next and subsequent program loops is affirmed in S110 and the process proceeds to S138, and the bit of the rotation speed abnormality detection history flag F_XICSRCSR is set to 1. That is, when the bit of the flag F_XICSRCD is set to 1, it means that there is a history in which a state where the engine speed NE continues for the first predetermined time Ta and is not within the predetermined range NEb is detected.

  Next, in S140, it is determined whether or not the bit of the rotational speed convergence flag F_NETRGCNV (initial value 0) indicating that the engine rotational speed NE has converged to the target idle rotational speed NEa is 1. The bit of the flag F_NETRGCNV is set to 1 when the engine speed NE converges to the target idle speed NEa by feedback control executed after detecting an abnormality of the ISC valve 22, as will be described later. 0.

  Therefore, when the process of S140 is executed for the first time, it is usually denied and the subsequent processes are skipped. If the result of the next program loop is YES in S140, the process proceeds to S142, and the bit of the rotation speed abnormality detection flag F_XOBXISCS is set to 0.

  As described above, when the engine speed NE converges to the target idle speed NEa by feedback control (when the result in S140 is affirmative), the bit of the engine speed abnormality detection flag F_XOBXISCS is set to 0 (S142). For example, it is determined that the engine speed NE is normal and the ISC valve 22 is not abnormal (normal).

  If the bit of the flag F_XOBXISCS is set to 0 in S142 and the result is negative in S110 in the subsequent program loop, since the bit of the flag F_XISCSRCD is set to 1 in S138, the result is affirmed in S116 and S118 to S124. Is skipped, that is, the process of determining whether or not the engine 10 has been started when the throttle valve 14 is at the idle opening is skipped, and the processes after S126 described above are performed.

  Returning to the description of FIG. 4, the process then proceeds to S <b> 18 to determine whether or not the bit of the rotation speed abnormality detection flag F_XOBXISCS is “1”. When the result in S18 is negative, the program proceeds to S20, in which it is determined whether or not the engine speed NE is within the predetermined range NEb. When the current program loop is executed, for example, immediately after the ignition switch 66 is turned on or immediately after the starter switch 70 is turned on, the engine speed NE is normally not within the predetermined range NEb. , It is determined whether the bit of the flag F_XOBXISCS is 1.

  When the result in S22 is negative, the program proceeds to S24, and the stepping motor 24 is subjected to open loop control. In S24, specifically, the step position of the stepping motor 24 is set to the ISC target step position (target step position), and the ISC valve 22 is controlled to have an appropriate opening degree corresponding to the engine temperature TW.

  Here, the above-described ISC target step position and target idle speed NEa will be described.

  FIG. 6 is a flowchart showing a process for calculating the ISC target step position and the target idle speed NEa. The illustrated program is executed by the ECU 74 in parallel with the processes of FIGS. 4 and 5 at predetermined intervals (for example, 100 msec).

  First, in S200, the engine temperature TW is detected (calculated) based on the output of the water temperature sensor 62. Next, in S202, the ISC target step position of the stepping motor 24 is calculated based on the detected engine temperature TW. The ISC target step position means the step position of the stepping motor 24 corresponding to the opening degree of the ISC valve 22 when the engine 10 is operated at the idle speed, and the value is set according to the engine temperature TW. . Specifically, the ISC target step position is obtained by searching a table showing the characteristics in FIG.

  As shown in FIG. 7, the ISC target step position is set so that the number of steps is large when the engine temperature TW is relatively low, that is, the ISC valve 22 has a high opening, and as the engine temperature TW increases. The number of steps is set to decrease (the ISC valve 22 has a low opening).

  Next, the routine proceeds to S204, where the target idle speed NEa is calculated based on the engine temperature TW. The target idle speed NEa is calculated by searching a table showing the characteristics in FIG. 8 from the detected engine temperature TW.

  As shown in FIG. 8, the target idle speed NEa is set to a high speed when the engine temperature TW is relatively low, and is set to a low speed as the engine temperature TW rises. The target idle speed NEa calculated in S204 is used when executing the setting of the predetermined range NEb, the feedback control, and the like. The tables shown in FIGS. 7 and 8 are obtained in advance through experiments and stored in the ROM 74h.

  Returning to the description of FIG. 4, when the result in S18 or S20 is affirmative, the program proceeds to S26, in which it is determined whether or not the throttle valve 14 is at the idle opening. If NO in S26, that is, if the accelerator is operated by the driver and the throttle valve 14 is not at the idle opening, the process proceeds to S22 and S24, and the above-described processing is performed. It is determined whether the value of a timer (described later) is zero. Since the initial value of the feedback restart delay timer is 0, when the process of S28 is executed for the first time, the determination is affirmative and the process proceeds to S30, and the feedback control stop determination process is executed.

  FIG. 9 is a sub-routine flowchart of the feedback control stop determination process in S30.

  First, in S300, it is determined whether feedback control has been executed in the previous program loop. When the process of S300 is performed for the first time, since feedback control is not yet executed, the result is negative and the process proceeds to S302, the engine speed NE is buffered in the RAM 74i as the value NEBUF, and the process proceeds to S304 where the ISC step position ISCSTEP is also a value. Similarly, buffering is performed in the RAM 74i as ISCSTEPBUF. Next, in S306, the ISC step drive required time measurement timer TMMFCHK (up counter) is set to 0, and the timer TMMFCHK is started. Other processing in FIG. 9 will be described later.

  Returning to the description of FIG. 4, the process then proceeds to S32, in which it is determined whether the bit of the feedback control stop flag F_ISCFBNG (described later) is 1. Since the initial value of the flag F_ISCFBNG is set to 0, when the process of S32 is executed for the first time, the result is negative and the process proceeds to S34, and the difference between the engine speed NE and the idle speed NEa is a predetermined value (for example, 20 rpm) in absolute value. Whether or not the following state continues for the second predetermined time Tb (for example, 3 seconds), in other words, the state where the engine speed NE is in the vicinity of the idle speed NEa continues for the second predetermined time Tb. Determine whether or not.

  When the result in S34 is negative, the program proceeds to S36, the bit of the rotation speed convergence flag F_NETRGCNV is set to 0, the program proceeds to S38, and feedback control is executed. In S38, specifically, the ISC valve is set via the stepping motor 24 so that the engine speed NE matches the idle speed NEa (more precisely, the idle speed NEa calculated in S204 of FIG. 6). The opening degree of 22 is feedback controlled (PID control). More specifically, when the engine speed NE exceeds the idle speed NEa, the ISC valve 22 is driven in the closing direction, while when the engine speed NE is less than the idle speed NEa, the ISC valve 22 is opened. The operation of the stepping motor 24 is controlled so as to drive.

  As can be seen from the above, the feedback control in S38 is basically performed when the throttle valve 14 is at the idle opening (Yes in S26) and the engine speed NE is not in the vicinity of the idle speed NEa (No in S34). Although it is executed, after detecting an abnormality in the engine speed NE (Yes in S18), the throttle valve 14 is at the idle opening (Yes in S26), and the engine speed NE is not in the vicinity of the idle speed NEa (S34). Is also executed).

  Next, in S40, it is determined whether or not the bit of the rotation speed abnormality detection flag F_XOBXISCS is 1. When the result in S40 is negative, the program proceeds to S42, and the feedback control elapsed time timer XTMISCS (up counter) is set to 0. When the result is affirmed, the program proceeds to S44 and the timer XTMISCS is started. That is, the timer XTMISCS indicates an elapsed time after the feedback control is executed after the abnormality of the engine speed NE is detected.

  Next, in S46, an abnormality determination process for the ISC valve 22 is executed.

  FIG. 10 is a sub-routine flowchart of the ISC valve abnormality determination process in S46 of FIG.

  First, in S400, it is determined whether or not the bit of the rotation speed abnormality detection flag F_XOBXICSS is 1. When the result in S400 is affirmative, the process proceeds to S402, and it is determined whether or not the timer XTMISCS is equal to or longer than a third predetermined time (predetermined time, for example, 30 sec) Tc. If the engine speed NE does not converge within the predetermined range NEb after the third predetermined time Tc has elapsed after executing feedback control after detecting an abnormality in the engine speed NE in S402, that is, when the abnormality is detected in the engine speed NE, the process proceeds to S404. Then, the bit of the ISC abnormality determination flag F_XAPXICS indicating that it is determined that an abnormality has occurred in the ISC valve 22 is set to 1. If the result in S400 or S402 is NO, the subsequent processing is skipped.

  Next, the process proceeds to S48 of FIG. 4 to execute an engine speed increase prevention process. Specifically, when it is determined in the process of FIG. 10 that an abnormality has occurred in the ISC valve 22, the engine speed NE may rise unnecessarily depending on the operating state (rising up), which may cause the driver to feel uncomfortable. Therefore, the ignition and fuel injection of the engine 10 are controlled in S48 to prevent the engine speed NE from increasing.

  FIG. 11 is a sub-routine flowchart of the engine speed increase prevention process.

  First, in S500, it is determined whether or not the bit of the ISC abnormality determination flag F_XAPXICSS is 1. If the determination is affirmative, the process proceeds to S502, in which it is determined whether or not the throttle valve 14 is at an idle opening. When the result in S502 is affirmative, the program proceeds to S504, in which it is determined whether or not the engine speed NE is equal to or greater than a predetermined engine speed NEc (specifically, the target idle engine speed NEa).

  When the result in S504 is affirmative, the program proceeds to S506, and a value obtained by subtracting the predetermined engine speed NEc from the engine engine speed NE is set as a deviation DNEXSC. Next, in S508, the ignition timing retardation correction value IGISCR is calculated based on the deviation DNEXSC. Specifically, the ignition timing retardation correction value IGISCR is obtained by searching a table showing the characteristics in FIG.

  As shown in FIG. 12, the ignition timing retardation correction value IGISCR is set to 0 deg when the deviation DNEXSC is relatively small, that is, a value that does not retard the ignition timing, while the ignition timing is increased as the deviation DNEXSC increases. It is set to a value that increases the amount of retardation of.

  Next, the process proceeds to S510, and similarly to S508, the fuel reduction correction value MISCLEAN is calculated based on the calculated deviation DNEXSC by searching a table showing its characteristics in FIG. As shown in FIG. 13, the fuel reduction correction value MISCLEAN is set to a value that is 1.0 times when the deviation DNEXSC is relatively small, that is, a value that does not reduce the fuel injection amount, while the fuel increases as the deviation DNEXSC increases. The amount by which the injection amount is decreased is increased. In other words, the value is such that the fuel injection amount is further decreased.

  Further, when the results in S500, S502, and S504 are negative, the engine speed NE does not increase unnecessarily, so the routine proceeds to S512, where the ignition timing retardation correction value IGISCR is set to 0 deg, and the routine proceeds to S514. The reduction correction value MISCLEAN is set to 1.0 times, that is, a value that does not correct the ignition timing and the fuel injection amount.

  Next, the routine proceeds to S516, where the basic ignition timing and the basic fuel injection calculated based on the engine speed NE, the intake pipe absolute pressure PBA, etc. in a program (not shown) according to the ignition timing retard correction value IGISSCR and the fuel reduction correction value MISCLEAN. Correct the amount. Specifically, a control signal indicating the ignition timing corrected by adding the ignition timing retardation correction value IGISSCR to the basic ignition timing is sent to the ignition coil 34 via the ignition circuit 74e, and the ignition timing is retarded. A control signal indicating a value corrected by multiplying the reference injection fuel amount by the fuel decrease correction value MISCLEAN is sent to the injector 26 via the drive circuit 74f to reduce the fuel injection amount. As a result, the engine speed NE can be prevented from unnecessarily rising (blowing), and the driver does not feel uncomfortable.

  Returning to the description of FIG. 4, when the bit of the ISC abnormality determination flag F_XAPXICSS is set to 1 in S404 of FIG. 10, in the next program loop, the determination in S10 is affirmative, and the process proceeds to S50 to energize the stepping motor 24. Stop. That is, when it is determined that an abnormality has occurred in the ISC valve 22, the stepping motor 24 is stopped.

  Further, by executing the feedback control in S38 after detecting an abnormality in the engine speed NE, the difference between the engine speed NE and the idle speed NEa is not more than a predetermined value in absolute value, that is, the engine speed NE is equal to the target idle speed. It may converge to the rotational speed NEa. In this case, the result is affirmative in S34, and the process proceeds to S52, where the ISC step position ISCSTEP is replaced with the step value of the ISC target step position calculated in S202 of FIG.

  That is, in S128 and S130 of FIG. 5, a value indicating the fully open position or the fully closed position of the ISC valve 22 is temporarily set in the ISC step position ISCSTEP, but the engine speed NE converges to the target idle speed NEa by feedback control. In this case, since it can be estimated that the step position of the stepping motor 24 is at the ISC target step position shown in FIG. 7, in S52, the ISC step position ISCSTEP is calculated based on the engine temperature TW. Replaced with step value at step position.

  Thereby, the deviation between the step position recognized by the ECU 74 caused by the step-out of the stepping motor 24 and the actual step position of the stepping motor (hereinafter also referred to as “actual step position”) can be corrected, and the ISC by the stepping motor 24 can be corrected. It becomes possible to ensure the control accuracy of the valve 22.

  Next, the process proceeds to S54, the bit of the rotation speed convergence flag F_NETRGCNV used in S140 described above is set to 1, the process proceeds to S56, and the driving of the stepping motor 24 is stopped, and then the processes of S46 and S48 are executed.

  14 and 15 are time charts for explaining the above-described processing. 14 shows a case where it is determined in S404 that an abnormality has occurred in the ISC valve 22, and FIG. 15 shows a case where it is determined that no abnormality has occurred (normal).

  Referring to FIG. 14, the case where it is determined that an abnormality has occurred in the ISC valve 22 will be described. First, the ignition switch 66 is turned on at time t1. When the starter switch 70 is turned on with the throttle valve 14 in the idling position (time point t2), cranking is started and the engine 10 is started, and the engine speed NE becomes equal to or higher than the complete explosion speed NEref (time point). t3, S112 to S124).

  When the engine speed NE is not within the predetermined range NEb in the state where the throttle valve 14 is still in the idling opening after the engine 10 is started, the abnormality detection timer is started (time t4). S126, S128). When the engine speed NE is not within the predetermined range NEb for the first predetermined time Ta (time t5, S128), the bit of the engine speed abnormality detection flag F_XOBXICSS is set to 1 (S130).

  Further, at time t5, the fully open step position is temporarily set at 22 in the ISC step position ISCSTEP (S134), and the ISC is set via the stepping motor 24 so that the engine speed NE coincides with the idle speed NEa. The opening degree of the valve 22 is feedback controlled (S38). Also, the feedback control elapsed time timer XTMISCS is started (S44).

  When the timer XTMISCS reaches the third predetermined time Tc, that is, when the engine speed NE does not converge within the predetermined range NEb after the third predetermined time Tc has elapsed since the execution of the feedback control (time t6, S402). When it is determined that an abnormality has occurred in the ISC valve 22, the bit of the ISC abnormality determination flag F_XAPXICSS is set to 1 (S404), and the energization to the stepping motor 24 is stopped (S50).

  On the other hand, as shown in FIG. 15, when the engine speed NE converges to the target idle speed NEa by feedback control started at time t5 (time t7, S34), the bit of the engine speed abnormality detection flag F_XOBXICSS is set to 0 ( In other words, it is determined that no abnormality has occurred in the ISC valve 22 (normal). Further, at time t7, the ISC step position ISCSTEP is replaced with the step value of the ISC target step position (S52), and the deviation between the step position recognized by the ECU 74 and the actual step position of the stepping motor 24 is corrected.

  Returning to the description of the flowchart of FIG. 4, the feedback control stop determination process described above will be described.

  As described above, the feedback control drives the ISC valve 22 by controlling the operation of the stepping motor 24 so that the engine speed NE coincides with the idle speed NEa. When such feedback control is executed, the intake air amount may be insufficient depending on the driving state of the vehicle, and the engine 10 may stall.

  That is, for example, when traveling on a downhill road in a state where the output of the engine 10 is transmitted to the rear wheels (drive wheels) via the transmission and the clutch, the crankshaft 42 of the engine 10 is rotated by an external force acting from the road surface. The engine speed NE is kept constant (or increased). If the engine speed NE exceeds the target idle speed NEa in such a state, the ISC valve 22 is driven in the closing direction to reduce the intake air amount by feedback control. At that time, power transmission between the engine 10 and the rear wheel is cut off by the clutch, and if the ISC valve 22 is in the vicinity of the fully closed position, the intake air amount is insufficient, the engine speed NE decreases, and the engine 10 There is a risk of stalling.

  Therefore, in the control apparatus for an internal combustion engine according to the present invention, during the feedback control, the correlation between the drive of the ISC valve 22 and the engine speed NE that fluctuates due to the drive of the ISC valve 22 is monitored, and the feedback control is executed. The feedback control is stopped when it can be judged that the driving state is not necessary.

  Specifically, when the process of S30 is executed during the execution of the feedback control in the flowchart of FIG. 4, the feedback control stop (stop) determination process shown in FIG. 9 is performed.

  As shown in FIG. 9, first, in S300, as described above, it is determined whether feedback control has been executed in the previous program loop. Since the current program loop is executing feedback control, an affirmative decision is made in S300 and the routine proceeds to S308, where it is determined whether or not the ISC valve 22 is continuously driven by the stepping motor 24 for a predetermined number of steps ISCSTEPref (for example, 20 steps). . This is determined based on whether or not the difference between the ISC step position ISCSTEP and the value ISCSTEPBUF buffered in S304 is equal to or greater than a predetermined step number ISCSTEPref.

  When the result in S308 is negative, the subsequent processing is skipped. When the result is affirmative, the process proceeds to S310, and it is determined whether or not the ISC step position ISCSTEP is greater than or equal to the value ISCSTEPBUF. When the result in S310 is affirmative, that is, when the ISC valve 22 is driven in the opening direction, the process proceeds to S312 and the bit of the opening direction driving flag F_DSTEPFB is set to 1. On the other hand, if the result in S310 is NO, that is, if the ISC valve 22 is driven in the closing direction, the process proceeds to S314, and the bit of the opening direction driving flag F_DSTEPFB is set to 0.

  Next, in S316, a change amount DNEFB of the engine speed NE is calculated. Specifically, the change amount DNEFB is an absolute value of a difference obtained by subtracting the value NEBUF buffered in S302 from the engine speed NE.

  Next, in S318, it is determined whether or not the engine speed NE is greater than or equal to the value NEBUF buffered in S302. When the result in S318 is affirmative, the program proceeds to S320, in which the bit of the rotation speed increase flag F_DNEFB is set to 1, while when the result is negative, the program proceeds to S322, and the bit of the flag F_DNEFB is set to 0. Therefore, when the bit of the engine speed increase flag F_DNEFB is set to 1, the engine speed NE is increasing (increasing), and when it is set to 0, the engine speed NE is decreasing (decreasing). Means that

  Next, in S324, it is determined whether or not the value of the timer TMFBCHK started in S306 described above is equal to or greater than a predetermined timer value. The predetermined timer value is set to such a value that it can be determined that the operation of driving the ISC valve 22 for a predetermined number of steps in the opening direction or the closing direction is continuously performed, for example, 200 msec.

  More specifically, the stepping motor 24 is driven at a driving frequency of 200 pps (that is, it takes 5 msec to drive one step). When the predetermined number of steps ISCSTEPref is set to 20 steps, for example, when the ISC valve 22 is continuously driven, a time of 100 msec is required. Therefore, by setting the predetermined timer value to 200 msec, it can be determined that the timer is continuously driven if the value of the timer TMFBCHK is less than the predetermined timer value, while it is driven over a relatively long time if it is equal to or greater than the predetermined timer value. In other words, it can be determined that it is not driven continuously.

If negative in S324 proceeds to S326, the change direction of the engine rotational speed NE with respect to the opening and closing direction of the ISC valve 22 is determined whether they match. This is determined by whether or not the bits of the opening direction drive flag F_DSTEPFB and the rotation speed increase flag F_DNEFB match.

  More specifically, in S326, the engine speed NE decreases despite the ISC valve 22 being driven in the opening direction (that is, the intake air amount is increasing). Although the engine speed NE rises despite being driven in the closing direction (that is, the intake air amount is decreasing), the ISC valve 22 increases or decreases the intake air amount and the engine speed NE increases or decreases. This is a process in which it is determined that it is not necessary to execute feedback control when the operating states do not match.

  When the result in S326 is affirmative, the program proceeds to S328, in which it is determined whether or not the engine speed change amount DNEFB is less than a predetermined value DNEFBref. If the result in S328 is affirmative or the result in S326 is negative, it is determined that the engine 10 may stall as described above, and it is determined that there is no need to execute feedback control. The process proceeds to S330 and the feedback control stop flag F_ISCFBNG Set the bit of.

  On the other hand, when the result in S324 is affirmative or the result in S328 is negative, it is determined that the operation state where the feedback control may be executed is determined, and the process proceeds to S332, and the bit of the feedback control stop flag F_ISCFBNG is set to 0. After the processing of S330 or S332, the processing of S302 to S306 described above is executed, and the process returns to the flowchart of FIG.

When the bit of the flag F_ISCFBNG is set to 0 in S332 proceeds to the processing in Step S10 S34 are negated by S 32, it continues to execute the feedback control. On the other hand, when the bit of the flag F_ISCFBNG is set to 1 in S330, the result is affirmed in S32 and the process proceeds to S58, and a predetermined delay timer value (predetermined stop time) is set to the value of the feedback restart delay timer (down counter). Since the feedback restart delay timer is a timer that avoids (prevents) feedback control from being stopped for a long time, the predetermined delay timer value is set to an appropriate time (for example, 5 sec).

  Next, when the result in S22 is negative, the program proceeds to S24, where the feedback control is stopped (instead of the feedback control), and the open loop control of the stepping motor 24 is performed. In this way, during the feedback control, the ISC valve 22 is continuously driven in the opening direction or the closing direction for a predetermined number of steps (predetermined number of steps ISCSTref), and the engine speed change amount DNFB is a predetermined value DNFBBref. When less than, feedback control is stopped.

In the next and subsequent program loop, until the value of the feedback restart delay timer reaches zero is negative in S 28, to continue the open-loop control. When the value of the feedback restart delay timer becomes 0 (in other words, after a predetermined stop time has elapsed since the feedback control was stopped), the open loop control is switched to the feedback control, that is, the feedback control is restarted. .

As described above, in the embodiment of the present invention, the throttle valve 14 disposed in the intake passage 12 of the internal combustion engine (engine) 10, the bypass passage 20 connected to the intake passage and bypassing the throttle valve, And an idle speed control valve (ISC valve) 22 that adjusts the air amount of the bypass passage to adjust the idle speed NEa of the internal combustion engine, and a stepping motor 24 that drives the idle speed control valve. In the control apparatus for an internal combustion engine, the internal combustion engine 10 is started when the throttle valve 14 is at the idle opening, and after the start, it is determined whether the idle opening is still at the idle opening. State determination means (ECU 74, S16, S112 to S124), and when it is determined that the idle opening start state A rotational speed range determining means for determining whether or not the rotational speed NE of the internal combustion engine is within a predetermined range NEb set according to the target idle rotational speed NEa (ECU 74; S16, S126); When it is determined that NE is not within the predetermined range NEb, the idling engine speed control valve 22 is opened via the stepping motor 24 so that the engine speed NE of the internal combustion engine matches the target idle engine speed NEa. Feedback control means for performing feedback control of the degree (ECU 74, S38), and after a predetermined time (third predetermined time) Tc has elapsed since the execution of the feedback control, the rotational speed NE of the internal combustion engine is within the predetermined range NEb. And an abnormality determining means for determining that an abnormality has occurred in the idle speed control valve 22 when it does not converge to ( CU74.S46, with S400～S404), the idle opening start state determining means, the throttle valve 14 is not even driven history once the idle opening, and the rotational speed NE of the internal combustion engine complete explosion the internal combustion engine is configured as judged to have been started when less than the rotational speed NEref.

  As a result, the abnormality of the ISC valve 22 can be detected (detected) without requiring a device (for example, a vehicle speed sensor) that specifically detects the no-load state of the engine as in the prior art, although it has a simple configuration. ) As well as cost advantages.

  Further, temperature detecting means for detecting the temperature (engine temperature) TW of the internal combustion engine (water temperature sensor 62. ECU 74, S200), and a target step position (stepping motor 24) based on the detected temperature TW of the internal combustion engine ( Target step position calculation means for calculating (ISC target step position) (ECU 74, S202), and based on the detected temperature TW of the internal combustion engine, during the execution of the feedback control, the rotational speed NE of the internal combustion engine and the target Since it is configured to include replacement means for replacing the position of the stepping motor 24 with the step value of the target step position when the difference in the idle speed NEa is equal to or less than a predetermined value (ECU 74, S34, S52), for example, a stepping motor Step recognized by ECU 74 caused by step-out of 24 Can modify the deviation between the location (ISC step position ISCSTEP) and the actual step position of the stepping motor (actual step position), it is possible to ensure the control accuracy of the ISC valve 22 by the stepping motor 24.

Further, the abnormality to the idle speed control valve 22 is determined to have occurred when the rotational speed NE of the internal combustion engine is equal to or greater than a predetermined rotational speed N c, at least one of ignition and fuel injection of the internal combustion engine 10 Since it is configured to include a rotation speed increase prevention means for controlling any one to prevent an increase in the rotation speed NE of the internal combustion engine (ECU 74. S48, S500 to S516), the engine when an abnormality occurs in the ISC valve 22 Unnecessary increase (blow-up) of the rotational speed NE can be effectively prevented.

  Further, the feedback control means is configured to drive the idle speed control valve 22 in a predetermined number of steps (predetermined number of steps) ISCSTrefref continuously in the opening direction or the closing direction during the execution of the feedback control. When the amount of change DNEFB in the engine speed is less than the predetermined value DNEFBref, the feedback control is stopped (ECU 74. S24, S30, S32, S300 to S332), so that it is not necessary to execute the feedback control. Sometimes the feedback control can be stopped, thus preventing the engine 10 from stalling.

The feedback control means is configured to resume the feedback control after a predetermined suspension time has elapsed since the feedback control was suspended (when the value of the feedback restart delay timer becomes 0) (the ECU 74). S58, S 28), it is possible to resume an effective timing feedback control which has been discontinued.

  In the above description, the ISC target step position and the target idle speed NEa are calculated based on the engine temperature TW. However, the present invention is not limited to this. For example, in addition to the engine temperature TW, the intake air temperature TA, The calculation may be performed in consideration of the absolute pressure PBA in the intake passage, the amount of change in an electric load such as an air conditioner or a radiator fan (not shown).

  In the engine speed increase prevention process, the ignition timing is retarded and the fuel injection amount is reduced. However, the present invention is not limited to this, and the engine speed NE is cut by performing ignition cut or fuel cut. You may make it prevent a raise of. From that point of view, it is stated in claim 3 that “at least one of ignition and fuel injection of the internal combustion engine is controlled to prevent an increase in the rotational speed of the internal combustion engine”.

  Moreover, although the predetermined range NEb, the predetermined time Tc, the predetermined delay timer value, the displacement of the engine 10 and the like are shown as specific values, these are examples and are not limited.

  In addition, although a two-wheeled vehicle is cited as an example of the vehicle, the present invention is not limited to this. For example, a so-called saddle-type vehicle in which a driver rides over a seat (saddle) such as a scooter or an ATV (All Terrain Vehicle). Any other vehicle (for example, a four-wheeled vehicle) may be used.

It is the schematic which shows typically the control apparatus of the internal combustion engine which concerns on the Example of this invention. FIG. 2 is an enlarged schematic cross-sectional view showing the vicinity of an ISC valve and a stepping motor shown in FIG. 1 in an enlarged manner. FIG. 2 is a block diagram showing the overall configuration of an ECU shown in FIG. 1. 2 is a flowchart showing the operation of the control device for the internal combustion engine shown in FIG. 1. 5 is a sub-routine flow chart of a rotation speed abnormality detection process of FIG. 4. FIG. 5 is a flowchart showing an ISC target step position and target idle speed calculation process used in the process of FIG. 4 and the like. 6 is a graph showing a characteristic of the engine temperature with respect to the ISC target step position calculated by the processing of the flowchart of FIG. 6 is a graph showing the engine temperature characteristic with respect to the target idle speed calculated by the processing of the flow chart of FIG. 5 is a sub-routine flowchart of the feedback control stop determination process of FIG. 4. 5 is a sub-routine flowchart of the ISC valve abnormality determination process of FIG. 4. 5 is a sub-routine flowchart of the engine speed increase prevention process of FIG. 4. FIG. 12 is a graph showing a characteristic of deviation of the engine speed with respect to the ignition timing retardation correction value calculated by the processing of the flowchart of FIG. 11. It is a graph which shows the characteristic of the deviation of an engine speed with respect to the fuel reduction correction value calculated by the process of FIG. 11 flow chart. 2 is a time chart showing the operation of the control device for the internal combustion engine shown in FIG. 1. FIG. 15 is a time chart similar to FIG. 14 showing the operation of the control device for the internal combustion engine shown in FIG. 1.

Explanation of symbols

10 engine (internal combustion engine), 12 intake passage, 14 throttle valve, 20 bypass passage, 22 ISC valve (idle speed control valve), 24 stepping motor,
62 Water temperature sensor, 74 ECU (electronic control unit)

Claims (5)

A throttle valve disposed in an intake passage of the internal combustion engine, a bypass passage connected to the intake passage and bypassing the throttle valve, and an air amount of the bypass passage is adjusted to adjust an idle speed of the internal combustion engine In a control apparatus for an internal combustion engine comprising an idle speed control valve and a stepping motor that drives the idle speed control valve, the internal combustion engine is started when the throttle valve is at an idle opening, and And an idle opening start state determining means for determining whether or not the engine is still at the idle opening, and when the idling opening start state is determined, the rotational speed of the internal combustion engine depends on the target idle rotational speed. A rotation speed range determination means for determining whether or not the rotation speed is within the predetermined range, and the rotation speed of the internal combustion engine is within the predetermined range. Feedback control means for feedback controlling the opening of the idle speed control valve via the stepping motor so that the speed of the internal combustion engine matches the target idle speed, and the feedback An abnormality determination means for determining that an abnormality has occurred in the idle rotation speed control valve when the rotation speed of the internal combustion engine does not converge within the predetermined range after a predetermined time has elapsed since execution of the control, and The idle opening start state determination means starts the internal combustion engine when there is no history that the throttle valve has been driven from the idle opening even once and the rotational speed of the internal combustion engine is less than the complete explosion rotational speed. A control apparatus for an internal combustion engine, wherein   A temperature detecting means for detecting the temperature of the internal combustion engine; a target step position calculating means for calculating a target step position of the stepping motor based on the detected temperature of the internal combustion engine; and a detected temperature of the internal combustion engine. And replacing means for replacing the position of the stepping motor when the difference between the rotational speed of the internal combustion engine and the target idle rotational speed is equal to or less than a predetermined value during execution of the feedback control with a step value of the target step position. The control apparatus for an internal combustion engine according to claim 1, further comprising:   When it is determined that an abnormality has occurred in the idle speed control valve, and the rotational speed of the internal combustion engine is equal to or higher than a predetermined rotational speed, at least one of ignition and fuel injection of the internal combustion engine is controlled to The control apparatus for an internal combustion engine according to claim 1 or 2, further comprising a rotation speed increase preventing means for preventing a rotation speed of the internal combustion engine from increasing.   The feedback control means is configured to drive the idle speed control valve continuously in the opening direction or the closing direction for a predetermined number of steps during the execution of the feedback control, and the amount of change in the rotational speed of the internal combustion engine is a predetermined value. The control apparatus for an internal combustion engine according to any one of claims 1 to 3, wherein the feedback control is stopped when the value is less than the value.   5. The control apparatus for an internal combustion engine according to claim 4, wherein the feedback control means restarts the feedback control after a predetermined stop time has elapsed since the feedback control was stopped.

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