JP5027792B2 - 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.

  As described above, when the idle speed control valve is driven by the stepping motor, the stepping motor is stepped out due to, for example, negative pressure in the bypass passage, vibration of the internal combustion engine, battery voltage drop, etc., and idle speed control is performed. Valve control accuracy may be reduced. Therefore, in the technique described in Patent Document 1 below, when the ignition switch is turned on, the idle speed control valve is driven to the fully open position, and the position of the stepping motor when reaching the fully open position is set to the fully open step position. The initialization process set as is executed.

By the way, when the internal combustion engine is started before the idle speed control valve reaches the fully open position in the initialization process, that is, when the cranking is started after the ignition switch is turned on (the starter switch is turned on). (If the start position of the ignition switch is selected), since the idle speed control valve is near the fully open position, the speed of the internal combustion engine will rise unnecessarily (rising up), and the driver may feel uncomfortable. there were. In order to prevent such an unnecessary increase in the engine speed, the technique described in Patent Document 1 is configured such that the ignition timing is retarded or the fuel is cut during the initialization process.
JP 2008-144700 A

  However, if the ignition timing is retarded during the initialization process as described above, the temperature of the exhaust gas rises and unburned gas is generated due to deterioration of combustion. As a result, exhaust system parts, particularly the catalyst device There was a risk of deterioration or damage. In addition, when performing fuel cut, there has been a problem that hunting of the engine speed occurs and the driver feels uncomfortable.

  Accordingly, the object of the present invention is to solve the above-mentioned problems, and when the internal combustion engine is started during the execution of the initialization process of the stepping motor, the rotational speed of the internal combustion engine is not caused without deteriorating the components of the exhaust system. An object of the present invention is to provide a control device for an internal combustion engine that prevents an unnecessary increase of the engine.

  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 an internal combustion engine control device comprising an idle speed control valve for adjusting the idle speed of the internal combustion engine by adjusting the air amount of the engine, and a stepping motor for driving the idle speed control valve, an ignition switch is turned on Initialization is performed to drive the idle speed control valve to the fully open position by the stepping motor and to set the position of the stepping motor as the fully open step position when reaching the fully open position. Processing execution means, and the idle speed control valve in the initialization processing An initialization process stop means for stopping the initialization process when the internal combustion engine speed is equal to or higher than a predetermined speed before reaching the fully open position and the throttle valve is at an idle opening; Feedback control means for performing feedback control of the opening degree of the idle speed control valve via the stepping motor so that the rotational speed of the internal combustion engine coincides with a target idle speed when the control process is stopped It was configured as follows.

  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, the feedback control means drives 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 a fourth aspect, the feedback control means is configured to restart the feedback control after a predetermined time has elapsed since the feedback control was stopped.

  In the control device for an internal combustion engine according to claim 1, the rotational speed of the internal combustion engine becomes equal to or higher than a predetermined rotational speed before the idle rotational speed control valve reaches the fully open position in the initialization process of the stepping motor, and the throttle When the valve is at the idle opening, the initialization process is stopped, and when the initialization process is stopped, the engine speed is set via the stepping motor so that the engine speed matches the target engine speed. The control valve is configured to feedback-control the opening of the control valve, i.e., when the internal combustion engine is started to a predetermined speed during the initialization process and the throttle valve is at the idle opening, the idle speed control valve is Idle speed control so that the operation to drive to the fully open position is stopped and the speed of the internal combustion engine matches the target idle speed Since the valve opening is feedback controlled, when the internal combustion engine is started during the initialization process of the stepping motor, an unnecessary increase (swing) in the rotational speed of the internal combustion engine is prevented. Can do. Also, unlike the conventional technology, the ignition timing is not retarded or fuel cut is not performed, and the opening of the idle speed control valve is adjusted to adjust the intake air amount, thereby preventing unnecessary increase in engine speed. Thus, there is no problem that the driver feels uncomfortable due to deterioration or breakage of exhaust system parts (for example, the catalyst device) or hunting of the engine speed.

  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). In addition to the effects described above, even if the setting of the stepping motor when reaching the fully open position by stopping the initialization process is not set as the fully open step position, the rotational speed of the internal combustion engine is By replacing the position of the stepping motor when it converges to the target idle speed with the step value of the target step position, Can modify the deviation between the actual step position of the step of recognizing the position and the stepping motor controller caused by loss of synchronism of Ngumota, it is possible to ensure the control accuracy of the idle speed control valve by the stepping motor.

  In the control device for an internal combustion engine according to claim 3, during 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 apparatus for an internal combustion engine according to claim 4, since the feedback control is resumed after a predetermined time has elapsed since the feedback control was stopped, in addition to the effect described in claim 3, the stop The feedback control that has been performed can be resumed 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. To do.

  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 description, it is first determined in S10 whether or not the ignition switch 66 is turned on for the first time. In other words, it is determined whether or not the current program loop is the first (first) program loop after the ignition switch 66 is turned on. . In the first program loop, the determination is naturally affirmed and the process proceeds to S12, and an initialization process execution flag F_ISCINRQ (described later) is set to 1. In the second and subsequent program loops, the result in S10 is negative and S12 is skipped.

  Next, the routine proceeds to S14 where the engine rotation NE is detected (calculated) based on the output of the crank angle sensor 64, and the routine proceeds to S16 where the opening θTH of the throttle valve 14 is detected (calculated) based on the output of the throttle opening sensor 54. To do. Next, in S18, it is determined whether or not the engine speed NE is equal to or higher than the complete explosion speed NEref (predetermined speed, for example, 750 rpm).

  In the program loop immediately after the ignition switch 66 is turned on, the engine speed NE is normally less than the complete explosion speed NEref. Therefore, the result in S18 is negative and the process proceeds to S20, and the initialization process execution flag F_ISCINRQ is 1 or not. Judge. Since this flag is set to 1 in the process of S12, the result in S20 is affirmative and the process proceeds to S22, and the initialization process of the stepping motor 24 is executed.

  In the initialization process, the stepping motor 24 is stepped out due to the negative pressure of the bypass 20 or the vibration of the engine 10, and the step position of the stepping motor 24 recognized by the ECU 74 and the actual step position of the stepping motor 24 (hereinafter “ This is a process of correcting and initializing the deviation.

  FIG. 5 is a sub-routine flowchart of the initialization process of the stepping motor 24 in S22 of FIG.

  First, in S100, it is determined whether or not the initialization process has been executed in the previous program loop. Since this program loop is the first time, the determination is negative and the process proceeds to S102, where an initial value at start (specifically, 0 step) is set to the ISC step position ISCSTEP indicating the step position of the stepping motor 24 recognized by the ECU 74. Then, the bit of the full opening butting process completion flag F_ISCINOPN (described later) is reset to 0. When the initialization process is performed in the previous program loop, the result in S100 is affirmative and S102 is skipped.

  Next, in S104, it is determined whether or not the bit of the full opening butting process completion flag F_ISCINOPN is 1. Since the flag F_ISCINOPN is set to 0 in S102, the result in S104 is negative and the process proceeds to S106, where it is determined whether or not the ISC step position ISCSTEP is equal to or greater than the first predetermined step number ISCSTEPref1. Specifically, the first predetermined number of steps ISCSTEPref1 is set to the number of steps when the ISC valve 22 is driven from the fully closed position to the fully opened position in the stepping motor 24, for example, 200 steps. Therefore, S106 is a process for determining whether or not the stepping motor 24 has been driven to reach the ISC valve 22 to the fully open position.

  In this program loop, since the ISC step position ISCSTEP is 0 step, the result of S106 is negative, the process proceeds to S108, the value of the ISC step position ISCSTEP is incremented by one, the process proceeds to S110, and the ISC valve 22 is set via the stepping motor 24. Is driven in the opening direction by one step.

  In the next and subsequent program loops, the processes of S108 and S110 are repeated, and when the ISC step position ISCSTEP is equal to or greater than the first predetermined number of steps ISCSTEPref1, the result in S106 is affirmative and the process proceeds to S112. 200 steps (full open step position) is set, and the full open butting process completion flag F_ISCINOPN is set to 1. Therefore, setting this flag F_ISCINOPN to 1 means that the process of driving the ISC valve 22 to the fully open position by the stepping motor 24 and hitting it against the stopper has been completed. Means not completed.

  Thus, when the ignition switch 66 is turned on, the ISC valve 22 is driven to the fully open position by the stepping motor 24, and the position (ISCSTEP) of the stepping motor 24 when reaching the fully open position is set to the fully open step value (200 steps). (Fully open step position)). Thereby, the step position of the stepping motor 24 recognized by the ECU 74 and the actual step position of the stepping motor 24 can be matched, and the control accuracy of the ISC valve 22 by the stepping motor 24 can be improved.

  In S112, when the bit of the full opening butting process completion flag F_ISCINOPN is set to 1, in the next program loop and subsequent, an affirmative decision is made in S104 and the process proceeds to S114, and the ISC step position ISCSTEP is set to the ISC target step position (target step position). Determine whether you are doing it.

  Here, the above-described ISC target step position will be described.

  FIG. 6 is a flowchart showing a process for calculating an ISC target step position and a target idle speed described later. 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 feedback control or the like to be described later. 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. 5, in S114, it is determined whether or not the ISC step position ISCSTEP matches the ISC target step position calculated by the above processing. Since the ISC step position ISCSTEP is the step position when the ISC valve 22 reaches the fully open position in S112 (full open step value, 200 steps), the ISC step position is normally denied and proceeds to S116, and the value of the ISC step position ISCSTEP is set to one. The decrement is advanced to S118, and the ISC valve 22 is driven in the closing direction by one step via the stepping motor 24.

  In the next and subsequent program loops, the processes of S116 and S118 are repeated, and when the ISC step position ISCSTEP matches (becomes equal to) the ISC target step position, the result of S114 is affirmative and the process proceeds to S120, and the initialization process execution flag F_ISCINRQ Is set to 0 and the initialization process is terminated. Therefore, the bit of the flag F_ISCINRQ being set to 1 means that the initialization process shown in FIG. 5 is being executed, and setting it to 0 means that the initialization process has been completed.

  When the bit of the initialization processing execution flag F_ISCINRQ is set to 0 in S120, the next program loop and subsequent program loops are denied in S20 and proceed to S24, and the stepping motor 24 is controlled in an open loop. Specifically, in S24, the step position of the stepping motor 24 is set to the ISC target step position calculated in S202 of FIG. 6, and the ISC valve 22 is controlled to an appropriate opening degree corresponding to the engine temperature TW. I do.

  By the way, when the engine 10 is started before the ISC valve 22 reaches the fully opened position in the initialization process described above, that is, when the cranking is started after the ignition switch 66 is turned on (the starter switch 70 is turned on). As described in the background art, since the ISC valve 22 is in the vicinity of the fully open position, the engine speed NE is unnecessarily increased (raised).

  Therefore, in the control apparatus for an internal combustion engine according to the present invention, when the engine speed NE is equal to or higher than the complete explosion speed (predetermined speed) NEref and the throttle valve 14 is at the idle opening, the initialization process is performed. At the same time, the opening of the ISC valve 22 is feedback-controlled through the stepping motor 24 so that the engine speed NE matches the target idle speed NEa.

  This will be described below. If the engine speed NE reaches the complete explosion speed NEref during the initialization process of the stepping motor 24, an affirmative determination is made in S18 and the routine proceeds to S26, where the throttle valve 14 is at the idle opening. Judge whether or not.

  When the result in S26 is negative, that is, when the accelerator is operated by the driver and the throttle valve 14 is not at the idle opening, the process proceeds to S20 and S24, and the above-described processing is performed. It is determined whether or not the bit of the initialization process execution flag F_ISCINRQ is 1. Since the initialization process is being performed here, the determination is affirmative and the process proceeds to S30, in which it is determined whether or not the bit of the full opening butting process completion flag F_ISCINOPN is 1.

  If NO in S30, that is, if it is determined that the ISC valve 22 is in a state before reaching the fully open position in the initialization process, the process proceeds to S32, and the bit of the initialization process execution flag F_ISCINRQ is set to 0.

  Next, in S34, an initial value (specifically, 200 steps) is set in the ISC step position ISCSTEP. That is, in S34, the process of setting the position of the stepping motor 24 when the ISC valve 22 reaches the fully opened position as the fully opened step position has not been completed, in other words, the ECU 74 determines the exact position of the stepping motor 24. In addition to the state before recognition, an initial value indicating the fully opened position of the ISC valve 22 is temporarily set in the ISC step position ISCSTEP in order to prepare for feedback control for driving the ISC valve 22 in the closing direction later.

  Next, in S36, the driving of the stepping motor 24 is stopped, the driving of the ISC valve 22 in the opening direction is stopped, and the program is terminated. Thus, when the engine speed NE is equal to or higher than the complete explosion speed (predetermined speed) NEref before the ISC valve 22 reaches the fully open position in the initialization process, and the throttle valve 14 is at the idle opening, Stop the initialization process.

  In the program loop after the initialization process is stopped, the bit of the initialization process execution flag F_ISCINRQ is set to 0 in S32. Therefore, the result in S28 is negative and the process proceeds to S38, and a feedback restart delay timer (described later) It is determined whether the value of is zero. Note that if the result in S30 is affirmative, the process proceeds to S38. Since the initial value of the feedback restart delay timer is 0, when the process of S38 is executed for the first time, an affirmative decision is made and the process proceeds to S40 to execute a feedback control stop determination process.

  FIG. 9 is a sub-routine flowchart of the feedback control stop determination process of S40.

  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 S42, 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 S42 is executed for the first time, the determination is negative and the process proceeds to S44, and the difference between the engine speed NE and the idle speed NEa is a predetermined value (for example, 20 rpm) in absolute value. It is determined whether or not the following state continues for a predetermined time (for example, 3 seconds), in other words, whether or not the state where the engine speed NE is in the vicinity of the idle speed NEa continues for a predetermined time.

  When the process of S44 is executed for the first time, the engine speed NE is usually not in the vicinity of the idle speed NEa, so a negative determination is made and the routine proceeds to S46, where feedback control is executed. In S46, 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.

  By executing the feedback control, when the difference between the engine speed NE and the idle speed NEa is equal to or smaller than the predetermined value in absolute value, that is, when the engine speed NE converges to the target idle speed NEa, the result in S44 is affirmative and the process proceeds to S48. Then, the ISC step position ISCSTEP is replaced with the step value of the ISC target step position calculated in S202 of FIG.

  That is, since the initialization process has been stopped (specifically, the process of setting the position of the stepping motor 24 as the fully open step position when the ISC valve 22 reaches the fully open position has not been completed), the process proceeds to S34. Although an initial value (200 steps) is temporarily set in the ISC step position ISCSTEP, when the engine speed NE converges to the target idle speed NEa by feedback control, the step position of the stepping motor 24 is shown in FIG. Since it can be estimated that the current position is the ISC target step position, in S48, the ISC step position ISCSTEP is replaced with the step value of the ISC target step position calculated based on the engine temperature TW.

  As a result, even if the setting of the stepping motor 24 at the fully opened step position is not set to the fully opened step position by stopping the initialization process, the ECU 74 recognizes the stepping motor 24 caused by the step-out of the stepping motor 24. The deviation between the step position to be performed and the actual step position of the stepping motor can be corrected, and the control accuracy of the ISC valve 22 by the stepping motor 24 can be ensured. After S48, the program proceeds to S36, where the driving of the stepping motor 24 is stopped and the program is terminated.

  FIG. 10 is a time chart for explaining the above processing. FIG. 10 shows the position of the ignition switch 66, the output of the starter switch 70, the actual step position (actual step position) of the stepping motor 24, the engine speed NE, and the ISC step position ISCSTEP in order from the top.

  As shown in FIG. 10, when the ignition switch 66 is turned on at time t1, initialization processing for the stepping motor 24 is started. Specifically, the operation of the stepping motor 24 is controlled to drive the ISC valve 22 toward the fully open position.

  When the starter switch 70 is turned on at time t2 before the ISC valve 22 reaches the fully open position, the engine 10 is started, and then the engine speed NE becomes equal to or higher than the complete explosion speed NEref (time t3). In that case, the initialization process is stopped, specifically, the driving of the stepping motor 24 is stopped and the driving of the ISC valve 22 in the opening direction is stopped, and the ISC step position ISCSTEP indicates the fully opened position of the ISC valve 22. A value (200 steps) is temporarily set.

  Then, the opening degree of the ISC valve 22 is feedback-controlled via the stepping motor 24 so that the engine speed NE matches the idle speed NEa. By feedback control, the ISC valve 22 is driven in the closing direction, and the engine speed NE converges to the target idle speed NEa, that is, when the difference between the engine speed NE and the target idle speed NEa is equal to or less than a predetermined value (time t4). ), The ISC step position ISCSTEP is replaced with the step value of the ISC target step position calculated based on the engine temperature TW, and the deviation between the step position recognized by the ECU 74 and the actual step position of the stepping motor 24 is corrected.

  It should be noted that when the engine speed NE is equal to or greater than the complete explosion speed NEref, the initialization process is continued, that is, when the ISC valve 22 is driven to the fully open position, the engine speed NE is indicated by a broken line in FIG. As you can see, it rises unnecessarily and blows up.

  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.

  More specifically, when the process of S40 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 the ISC valve 22 is continuously driven by the stepping motor 24 for the second predetermined number of steps ISCSTEPref2 (for example, 20 steps). Judge. This is determined by whether or not the difference between the ISC step position ISCSTEP and the value ISCSTEPBUF buffered in S304 is equal to or larger than the second predetermined step number ISCSTEPref2.

  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 second predetermined number of steps ISCSTEPref2 is set to 20 steps, for example, it takes 100 msec when driven continuously. Therefore, by setting the predetermined timer value to 200 msec, it can be determined that the ISC valve 22 has been continuously driven if the value of the timer TMFCBCHK is less than the predetermined timer value, while a relatively long time is required 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.

  When the result in S324 is negative, the program proceeds to S326, in which it is determined whether or not the direction of change of the engine rotation NE matches the opening / closing direction of the ISC valve 22. 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. 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, the result in S42 is negative and the process proceeds to S44 and subsequent steps, and feedback control is continuously executed. On the other hand, when the bit of the flag F_ISCFBNG is set to 1 in S330, the result in S42 is affirmative and the process proceeds to S50, and a predetermined delay timer value (predetermined 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, in S24, the feedback control is stopped (instead of the feedback control), and the stepping motor 24 is subjected to the open loop control described above. As described above, during the feedback control, the ISC valve 22 is continuously driven in the opening direction or the closing direction by a predetermined number of steps (second predetermined number of steps ISCSTEPref2), and the engine speed change amount DNEFB is When it is less than the predetermined value DNEFBref, the feedback control is stopped.

  In the next and subsequent program loops, the result of S38 is negative until the value of the feedback restart delay timer becomes 0, and the open loop control is continued. When the value of the feedback restart delay timer becomes 0 (in other words, after a predetermined 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 an internal combustion engine control apparatus, when the ignition switch 66 is turned on, the stepping motor 24 drives the idle speed control valve 22 to the fully open position, and the position of the stepping motor 24 when the fully open position is reached. Initialization process to set as the fully open step position (full open step value) (ECU 74. S22, S100 to S112), and in the initialization process, the rotational speed NE of the internal combustion engine reaches a predetermined speed before the idle speed control valve 22 reaches the fully opened position. Initializing process stop means for stopping the initializing process when the throttle valve 14 is at the idle opening (the ECU 74. S18, S26 to S36) and the initial value. Feedback control that feedback-controls the opening degree of the idle speed control valve 22 via the stepping motor 24 so that the engine speed NE of the internal combustion engine coincides with the target idle speed NEa when the control process is stopped. (ECU 74. S28, S46).

  In this way, when the engine 10 is started during the initialization process and reaches the predetermined rotation speed (complete explosion speed) NEref, and the throttle valve 14 is at the idle opening, the ISC valve 22 is driven to the fully open position. Since the operation is stopped and the opening degree of the ISC valve 22 is feedback-controlled so that the engine speed NE coincides with the target idle speed NEa, the engine 10 is in operation during the initialization process of the stepping motor 24. When the engine is started, it is possible to prevent the engine speed NE from being unnecessarily increased (as shown by a broken line in FIG. 10).

  Further, unlike the prior art, the ignition timing is not retarded or fuel cut is not performed, and the intake air amount is adjusted by adjusting the opening of the ISC valve 22, thereby preventing an unnecessary increase in the engine speed NE. Thus, there is no problem that the driver feels uncomfortable due to deterioration or breakage of exhaust system parts (for example, the catalyst device 50) or hunting of the engine speed NE. Further, in an internal combustion engine control device, the ignition timing and the fuel injection amount are generally corrected (engine temperature correction) in accordance with the engine temperature TW in consideration of changes in the viscosity of the engine oil due to temperature. Instead of retarding the ignition timing and cutting the fuel as in the prior art, the configuration as described above is configured to prevent the engine speed NE from being blown up, so that the influence on the engine temperature correction is reduced. be able to.

  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 A replacement means for replacing the position of the stepping motor 24 when the difference in the idle speed NEa is equal to or less than a predetermined value with a step value of the target step position is provided (ECU 74, S44, S48).

  As a result, even if the setting of the stepping motor 24 when reaching the fully open position by stopping the initialization process is not set to the fully open step position, the engine speed NE converges to the target idle speed NEa. By replacing the position of the stepping motor 24 with the step value of the target step position, the step position (ISC step position ISCSTEP) recognized by the ECU 74 caused by the step-out of the stepping motor 24 and the actual step position of the stepping motor 24 The deviation from (actual step position) can be corrected, and the control accuracy of the ISC valve 22 by the stepping motor 24 can be ensured.

  Further, the feedback control means drives the idle speed control valve 22 in a predetermined step number (second predetermined step number) ISCSTEPref2 continuously in the opening direction or the closing direction during execution of the feedback control, Since the feedback control is stopped when the amount of change DNEFB in the rotational speed of the internal combustion engine is less than a predetermined value DNEFBref (ECU 74. S24, S40, S42, S300 to S332), it is not necessary to execute the feedback control. The feedback control can be stopped during the operation state, and therefore the engine 10 can be prevented from stalling.

  Further, the feedback control means is configured to resume the feedback control after a predetermined time has elapsed since the feedback control was stopped (when the value of the feedback restart delay timer becomes 0) (ECU 74, S50, S38) It is possible to restart the feedback control that has been stopped at an effective timing.

  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 addition, although the specific rotation speed (complete explosion rotation speed) NEref, the predetermined value DNEFBref, the predetermined delay timer value, the exhaust amount 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. FIG. 5 is a sub-routine flowchart of the initialization process of the stepping motor 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. FIG. 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. 2 is a time chart 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, 70 ignition switch, 74 ECU (electronic control unit)

Claims (4)

  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 device for an internal combustion engine comprising an idle speed control valve and a stepping motor for driving the idle speed control valve, when the ignition switch is turned on, the idle speed control valve is fully opened by the stepping motor. And an initialization process execution means for executing an initialization process for setting the position of the stepping motor when reaching the fully open position as a fully open step position, and the idle speed control valve in the initialization process includes: The rotational speed of the internal combustion engine before reaching the fully open position An initialization process stop means for stopping the initialization process when the throttle valve is at an idle opening and the throttle valve is at an idle opening, and when the initialization process is stopped, the rotational speed of the internal combustion engine is A control device for an internal combustion engine, comprising feedback control means for feedback-controlling the opening degree of the idle speed control valve via the stepping motor so as to coincide with a target idle speed.   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:   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. 3. The control apparatus for an internal combustion engine according to claim 1, wherein the feedback control is stopped when the value is less than the value.   4. The control apparatus for an internal combustion engine according to claim 3, wherein the feedback control means restarts the feedback control after a predetermined time has elapsed since the feedback control was stopped.

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