JP2003106196A - Control system for engine idle control valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent backward flow of exhaust gas to an intake side during valve overlap period until engine stop and generation of airflow noise in closing an idle control valve caused by negative pressure in an intake pipe by avoiding large negative pressure's remaining in the intake pipe in downstream of a throttle valve when a standard position of the stepping motor type idle control valve is calibrated by ignition switch off. SOLUTION: Air is introduced to downstream of the throttle valve with keeping opening of the ISC valve equal to or greater than an established opening at ignition switch off to make pressure in the intake pipe in downstream of the throttle valve close to atmospheric pressure. Consequently, backward flow of exhaust gas to an intake system caused by valve overlap is avoided to prevent deterioration of re-startability of the engine, and generation of unpleasant airglow noise in opening ISC valve to prepare for next engine start after calibration at the full close position is prevented.

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for an engine idle control valve for calibrating a reference position of a step motor type idle control valve. 2. Description of the Related Art Generally, in a vehicle such as an automobile, an idle control valve is interposed in a bypass passage that bypasses an upper portion and a lower portion of an engine throttle valve, and an opening degree of the idle control valve is controlled. Accordingly, a technique for adjusting an intake air amount to maintain an idle rotation speed in an optimum state has been widely adopted, and some of such idle control valves employ a step motor as an actuator. In an idle control valve using this step motor, feedback control based on a deviation between a target engine speed and an actual engine speed is performed as engine speed control.
By taking advantage of the characteristic that the number of excitation steps of the step motor and the actual step position basically correspond, an open loop is formed without detecting the actual position by a position sensor or the like. For this reason, it is necessary to match the number of steps recognized by the control device for driving and controlling the step motor of the idle control valve with the actual number of steps of the step motor, and calibration of the reference position of the idle control valve (step motor) is required. Required. [0004] The calibration of the step motor type idle control valve is performed by turning off the step motor after the ignition switch is turned off as disclosed in, for example, JP-A-6-307267 and JP-A-11-257136. By moving to the mechanical limit point in the fully open or fully closed direction and applying an excessive number of steps to drive in the fully open or fully closed direction, the so-called abutting process, the fully open or fully closed step position is sent to the controller. A technique for making the recognition accurate is common. When the system is to be stopped after the completion of the calibration, the idle control valve is opened at a constant opening to secure the next smooth engine start. However, as in the technique disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 11-257136, the calibration operation at the fully closed position of the step motor type idle control valve is performed by ignition. If the switch is turned off, the throttle valve is fully closed due to the release of the accelerator pedal. Therefore, the negative pressure of the intake pipe downstream of the throttle valve is required until the rotation of the engine stops due to the operation of the idle control valve in the closing direction. Becomes larger, and the exhaust gas remaining in the exhaust system flows backward to the intake side during the valve overlap period in which the intake valve and the exhaust valve of any one of the cylinders are both open. Due to the influence, the startability may be deteriorated at the next engine start. Further, after calibrating the idle control valve at the fully closed position, if the idle control valve is opened at a constant opening in preparation for the next engine start, the negative pressure of the intake pipe downstream of the throttle valve is large. Therefore, the flow velocity of the air flowing from the intake system inlet side to the downstream side of the throttle valve through the idle control valve in the bypass passage becomes large, and there is a possibility that an airflow noise is generated to make the occupant feel uncomfortable. The same applies to the case where the idle control valve is calibrated at the fully open position. According to the technique disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 6-307267, after the ignition switch is turned off, the idle control is performed after the engine is stopped. Although the calibration operation is started by driving the valve in the fully open direction, the engine speed is feedback-controlled to the target speed by the normal control until the engine stops. It is controlled to a small opening, and similarly, there is a high possibility that a large negative pressure remains downstream of the throttle valve before the engine stops. For this reason, not only may there be a backflow of exhaust gas to the intake side due to valve overlap, but also there is a risk that airflow noise will be generated when calibration is started by driving the idle control valve in the fully open direction. SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and when calibrating a reference position of a step motor type idle control valve by turning off an ignition switch, it is possible to prevent a large intake pipe negative pressure from remaining downstream of the throttle valve. And
Engine idle control that can prevent exhaust gas from flowing back to the intake side during the valve overlap period until the engine stops due to the intake pipe negative pressure and air flow noise when the idle control valve is opened. It is intended to provide a valve control device. [0008] In order to achieve the above object, an invention according to claim 1 is a step motor type that is interposed in a bypass passage that bypasses an upstream side and a downstream side of an engine throttle valve. An engine idle control valve control device for calibrating the reference position of the idle control valve, wherein when the ignition switch is turned off, the idle control valve is held at a set opening or more for a set period, A calibration operation control means for starting a calibration operation of the idle control valve is provided. That is, according to the first aspect of the present invention, when the ignition switch is turned off, the step motor type idle control valve interposed in the bypass passage of the throttle valve is maintained at the set opening or more for the set period. Then, by starting the calibration operation of the idle control valve, even if the throttle valve is fully closed due to release of the accelerator pedal, the intake pipe pressure downstream of the throttle valve is brought to approximately atmospheric pressure by the time the engine is stopped. To prevent exhaust gas remaining in the exhaust system from flowing back to the intake system during the valve overlap period when both exhaust valves are open, and to calibrate the idle control valve at the fully closed position or at the fully open position. When the idle control valve is opened, high-speed air is prevented from flowing from the bypass passage to the downstream of the throttle valve through the idle control valve. To prevent the occurrence of such flow noise. Embodiments of the present invention will be described below with reference to the drawings. 1 to 4 relate to an embodiment of the present invention. FIG. 1 is an overall view of an engine system, FIG. 2 is a circuit configuration diagram of an electronic control system, FIG. 3 is a flowchart of an ISC control routine, and FIG. 5 is a time chart showing an intake pipe pressure behavior during operation. In FIG. 1, reference numeral 1 denotes an engine (in the figure, an in-line four-cylinder engine).
An intake manifold 3 communicates with each intake port 2a formed in the cylinder head 2, and an air chamber 4 in which the intake passage of each cylinder is gathered.
The intake pipe 5 is communicated through the. An air cleaner 6 is mounted on the intake air intake side of the intake pipe 5, and a throttle valve 7 is provided in the middle of the intake pipe 5. The throttle valve 7 has a throttle opening sensor for detecting a throttle opening. A throttle sensor 8 having a built-in throttle sensor 8a and an idle switch 8b that is turned ON when the throttle valve is fully closed is provided in series. An idle control valve (ISC valve) 10 for controlling an idle speed by a bypass air amount is interposed in a bypass passage 9 communicating the upstream and downstream of the throttle valve 7 of the intake pipe 5. I have. The ISC valve 10
This is a step motor type ISC valve having a step motor as an actuator for adjusting the valve opening.
Is driven by an electronic control unit 70 that controls Further, an intake air temperature sensor 11 faces the air chamber 4, and an intake pipe pressure sensor (absolute pressure sensor) 12 for detecting an intake pipe pressure downstream of the throttle valve 7 with an absolute pressure is attached. An injector 13 is located immediately upstream of each intake port 2 a of each cylinder of the intake manifold 3, and a knock sensor 14 is mounted on a cylinder block 1 a of the engine 1. A cooling water temperature sensor 16 faces the water passage 15. On the other hand, an exhaust pipe 18 is connected to an exhaust manifold 17 communicating with each exhaust port 2 b of the cylinder head 2, where the exhaust passage of each cylinder merges. A catalyst converter 19 is interposed in the exhaust pipe 18, an air-fuel ratio sensor 20 is located upstream of the catalyst converter 19, and a muffler 21 is provided at the terminal end. The cylinder head 2 of the engine 1 is provided with a spark plug 22 having a tip exposed to a combustion chamber for each cylinder. The spark plug 22 is connected to a secondary of an ignition coil 24 via a distributor 23. The igniter 25 is connected to the primary side of the ignition coil 24. A signal rotor 26 connected to a camshaft of the engine 1 is provided in the distributor 23,
A crank angle sensor 27 for detecting a crank angle and discriminating a cylinder is installed in the signal rotor 26. The igniter 25 includes an electronic control unit (EC
U) 70, an ignition signal is input, the current on the primary side of the ignition coil 24 is turned on and off, and the ignition plug 22 is ignited. That is, the ECU 70 is connected to the above-described sensors and actuators, and is connected to an ignition switch (indicated by IG in FIG. 1) 81 and a power supply relay 82 having two relay contacts. When the power supply relay 82 is turned on by turning on the 81, the ECU 70 is operated, the ignition timing is calculated, and a corresponding ignition signal is output from the ECU 70 to the igniter 25, and the current on the primary side of the ignition coil 24 is generated by the igniter 25. ON and OFF,
Thus, the high voltage induced on the secondary side is distributed to the ignition plug 22 of the cylinder to be ignited via the distributor 23, and the ignition plug 22 of the cylinder is ignited. Next, the ECU 70 and its peripheral systems will be described with reference to FIG. The ECU 70 includes a CPU 71, an RO
M72, RAM 73, backup RAM 74, counter / timer group 75, I / O interface 76, etc.
A constant voltage circuit 77 for supplying stabilized power to each unit, a driving circuit 78 connected to the I / O interface 76, an A / D
A peripheral circuit such as the converter 79 is built in. The counter / timer group 75 includes various counters such as a free-run counter, a fuel injection timer, an ignition timer, a periodic interrupt timer for generating a periodic interrupt, a timer for measuring an input interval of a crank angle sensor signal, and Various timers such as a watchdog timer for monitoring a system abnormality are generically referred to for convenience, and other various software counters and timers are used. Input ports of the I / O interface 76 include an idle switch 8b, a knock sensor 14, a crank angle sensor 27, and a vehicle speed sensor 2 for detecting a vehicle speed.
8, the ignition switch 81 and the like are connected,
Further, via the A / D converter 79, the intake pipe pressure sensor 1
2, throttle opening sensor 8a, cooling water temperature sensor 16,
The air-fuel ratio sensor 20 and the intake air temperature sensor 11 are connected, and the battery voltage VB is input and monitored.
On the other hand, the output port of the I / O interface 76
The base of an NPN transistor TR for self-shut described below is connected via a diode D (forward), an igniter 25 is connected, and further, via a drive circuit 78, an ISC valve 10 and an injector 13 Is connected. The transistor TR for self-shut has a base terminal connected to the battery 80 via an ignition switch 81 and an I / O via a diode D.
Connected to the output port of the interface 76,
The collector terminal is connected to a constant power supply line from the constant voltage circuit 77. The emitter terminal is connected to one end of a relay coil of the power supply relay 82, and the other end of the relay coil is grounded. The constant voltage circuit 77 is connected to the battery 80 via a first relay contact of a power supply relay 82 having two circuit relay contacts, and is directly connected to the battery 80.
The battery 80 has a constant voltage circuit 7
7, the first and second relay contacts of the ignition switch 81 and the power supply relay 82 are connected. Then, when the ignition switch 81 is turned on, the constant voltage circuit 77 is turned on.
Supplies a predetermined stabilizing voltage to each unit in the ECU 70 from the constant voltage circuit 77 regardless of whether the ignition switch 81 is ON or OFF.
A backup power is supplied to M74, and a power for self-shut is supplied to a collector of the transistor TR for self-shut. That is, when the ignition switch 81 is turned on, the battery voltage is applied from the battery 80 to the base terminal of the transistor TR for self-shut,
The transistor TR for self-shut is turned on, and power for self-shut is supplied to the relay coil of the power supply relay 82. By energizing the relay coil of the power supply relay 82, the first and second relay contacts are closed, and the battery voltage is supplied to the constant voltage circuit 77 via the first contact, and the battery voltage is reduced to a predetermined voltage and stabilized. The battery voltage is supplied to each unit in the ECU 70, and the battery voltage is supplied to each actuator via the second relay contact. When the power supply to the ECU 70 is turned on,
The control program stored in the ROM 72 is
1 and the system is initialized and the I / O
The voltage applied from the output port of the interface 76 to the base of the transistor TR for self-shut is kept at a high level, and the transistor TR for self-shut is kept on. Thus, the power supply to the ECU 70 is maintained regardless of whether the ignition switch 81 is ON or OFF. After system initialization, detection signals from sensors and switches, which are input via the I / O interface 76, and battery voltage are processed.
Various data stored in AM73, backup RAM
Various learning value data stored in the ROM 74 and the ROM 7
The fuel injection amount, ignition timing, target idle speed, and the like are calculated based on the fixed data and the like stored in 2, and engine control such as fuel injection control, ignition timing control, and idle speed control is executed. Thereafter, when the ignition switch 81 is turned off to stop the engine, the relay coil of the power supply relay 82 is kept energized and the power supply to the ECU 70 is held until the engine stop processing in the ECU 70 is completed. When the engine stop processing in the ECU 70 is completed, the output of the output port of the I / O interface 76 is inverted from the high level to the low level by the self-shut function of the ECU 70 itself, and the self-shut transistor TR is turned off. as a result,
The current to the relay coil of the power supply relay 82 is cut off, the first and second relay contacts are opened, the power supply to the ECU 70 and the actuators is cut off, and the system automatically stops. In this case, when the ignition switch 81 is turned off, the ECU 70 sets the ISC for a set period.
After the opening of the valve 10 is set to be equal to or larger than the set opening, air is introduced from the bypass passage 9 to the downstream of the throttle valve 7, and the intake pipe pressure downstream of the throttle valve 7 is reliably brought to the atmospheric pressure. Of the ISC to start the calibration operation of the
The system is stopped by opening the valve at a constant opening. In the present embodiment, the ignition switch 8
1 is turned off, until the engine is completely stopped, the opening of the ISC valve 10 is set to the set opening or more, and when the engine is completely stopped, the ISC valve 10 is abutted at the fully closed position. And calibrate the reference position. As a result, the ignition switch 81
Is turned off and the engine is stopped, even if the throttle valve 7 is fully closed by releasing the accelerator pedal, the intake pipe pressure downstream of the throttle valve 7 is set to approximately atmospheric pressure.
Exhaust gas remaining in the exhaust system during the valve overlap period in which the intake and exhaust valves are both open is prevented from flowing back to the intake system.
Further, after the calibration at the fully closed position of the ISC valve 10, when the ISC valve 10 is opened to a constant opening in order to ensure the next smooth engine start, the ISC valve 10 passes through the bypass passage 9 through the ISC valve 10. It is possible to prevent air with a high flow velocity from flowing into the downstream of the throttle valve 7 and prevent generation of unpleasant airflow noise. That is, the ECU 70 has a function as a calibration operation control means for the step motor type ISC valve 10 according to the present invention, and specifically, realizes the function by the routine shown in FIG. Hereinafter, a process related to the ISC control executed by the ECU 70 will be described with reference to FIG.
This will be described with reference to the flowchart of FIG. FIG. 3 shows the ignition switch 81
This is an ISC control routine that is executed at predetermined time intervals after the system is powered on and initialized by N. First, in step S1, it is checked whether or not the ignition switch 81 is turned off. Then, if the ignition switch 81 is ON, step S
Proceeding to 2, the normal target value for the opening of the ISC valve 10 is set. The normal opening target value is, for example, a basic opening based on the cooling water temperature, a load correction value by an air conditioner or a power steering pump, an acceleration / deceleration correction value for coping with a rapid opening / closing of the throttle valve 7, a target value. It is corrected and set by a feedback correction value based on a deviation between the engine speed and the actual engine speed calculated from the output of the crank angle sensor 27. Next, the process proceeds to step S3, where the lower limit of the ISC opening is set to 0, and in step S4, the previously set IS
It is checked whether the target value of the C opening is equal to or larger than the lower limit. As a result, if the target value of the ISC opening is equal to or larger than the lower limit, the process proceeds to step S6. If the target value of the ISC opening is lower than the lower limit, the target value of the ISC opening is reduced to the lower limit in step S5. And proceed to step S6. In step S6, the ISC opening is determined using the conversion table or the like.
Then, the step motor of the ISC valve 10 is driven by the converted step number, and the routine exits. On the other hand, when the ignition switch 81 is turned off to stop the engine, step S1 is executed.
Then, the process proceeds to step S7, where it is determined whether or not the engine speed based on the output of the crank angle sensor 27 has become 0, and it is determined whether the engine has been stopped due to ignition cut and fuel cut. Note that the ignition switch 81 is turned off.
However, the base voltage of the transistor TR for self-shut output from the output port of the I / O interface 76 does not change from the high level state, the transistor TR for self-shut is kept ON, and the power supply relay 82 is turned on. Is maintained. If it is determined in step S7 that the engine is still rotating by inertia and the crank has not been stopped, the process proceeds from step S7 to step S8, where IS
The lower limit of the C opening is newly set, and the process returns to the step S4 and thereafter to drive the step motor of the ISC valve 10 with the number of steps corresponding to the set opening equal to or larger than the lower limit. When the ignition switch 81 is turned off, the lower limit value of the ISC opening is set so that air is introduced from the bypass passage 9 and the throttle valve 7 is released by the time the crank stops when the throttle valve 7 is fully closed by releasing the accelerator pedal. It provides a minimum opening of the ISC valve 10 that can bring the downstream intake pipe pressure close to the atmospheric pressure and prevent the exhaust gas from flowing back to the intake side due to the valve overlap when both intake and exhaust valves are open. In consideration of the type and the configuration of the intake / exhaust system, an opening degree which is determined in advance by simulation or experiment to prevent exhaust gas backflow is stored in the ROM 72 as a lower limit value of the ISC opening degree when the ignition switch is turned off. It is something to keep. However, in this case, by increasing the opening of the ISC valve 10, it is possible to quickly increase the intake pipe pressure downstream of the throttle valve 7, but the opening of the ISC valve 10 becomes too large. And the bypass passage 9 and the ISC valve 1
0, there is a possibility that an abnormal noise may occur due to the airflow flowing from the upstream side to the downstream side of the throttle valve 7.
Is controlled so as not to generate an unpleasant airflow noise. Thereafter, when the rotation of the engine is stopped by stopping the crank, the process proceeds from step S7 to step 9 to determine whether or not the calibration operation of the ISC valve 10 is completed. Immediately after stopping the crank, the process advances from step S9 to step S10 according to the determination result of NO, and the IS for the calibration operation is
After setting the C opening target value, the process returns to step S6 to perform the IS operation with the number of steps corresponding to the ISC opening target value for the calibration operation.
The step motor of the C valve 10 is driven. The calibration operation of the ISC valve 10
The number of drive steps required to drive the step motor in the fully closed direction from the opening position set when the ignition switch is turned off, and to apply an excessive number of step excitations for a fixed time to perform the butting operation in the fully closed position By giving Then, after initializing the number of steps for the fully closed position of the ISC valve 10, the step motor is driven with a target value for keeping the ISC valve 10 at a constant opening to secure the next smooth engine start and to prevent the engine from malfunctioning. Prevents natural blow-up. At this time, as shown in FIG. 4A, when the ignition switch (IG SW) is turned off,
When the conventional technique for starting the calibration operation of the C valve 10 is applied, the engine stops while negative pressure accumulates downstream of the throttle valve 7 when the throttle valve 7 is fully closed by releasing the accelerator pedal. Therefore, if any of the cylinders is in a valve overlap state in which both the intake and exhaust valves are open before the engine stops, exhaust gas remaining in the exhaust system via the cylinder flows back to the intake system. And
At the next engine start, the startability deteriorates. Further, when the ISC valve 10 is opened to a constant opening after the initialization at the fully closed position, the ISC valve 10 is opened in a state where the pressure difference between the upstream and downstream of the throttle valve 7 is large.
As a result, the SC valve 10 is opened, and the air having a high flow rate from the inlet side of the intake system flows through the ISC valve 10 in the bypass passage 9 to the downstream of the throttle valve 7, and unpleasant noise is generated. On the other hand, in the present embodiment, as shown in FIG.
When the opening of the valve 10 is equal to or greater than the set opening, air is introduced from the bypass passage 9 to the downstream of the throttle valve 7, and the intake pipe pressure downstream of the throttle valve 7 when the crank stops is brought close to the atmospheric pressure.
This prevents the exhaust gas from flowing back into the intake system due to the valve overlap to prevent the engine restartability from deteriorating, and, after the calibration at the fully closed position, prepares the ISC valve for the next engine start. Even if the valve 10 is opened at a constant opening, since the downstream of the throttle valve 7 is already at substantially atmospheric pressure, almost no air flows into the downstream of the throttle valve 7 from the bypass passage 9, and unpleasant airflow noise is generated. Can be prevented. When the calibration operation of the ISC valve 10 is completed, this routine is completed, and the ECU 70 changes the base voltage of the self-shutoff transistor TR output from the output port of the I / O interface 76 by its own self-shutdown function. The level is inverted from the high level to the low level, and the transistor TR for self-shut is turned off. As a result, the power relay 82 is turned off and the ECU 7
Power is turned off to 0 and the system shuts down automatically. As described above, according to the present invention, when the ignition switch is turned off, the step motor type idle control valve interposed in the bypass passage of the throttle valve is set for the set period. The throttle valve is kept at or above the opening and then the calibration operation of the idle control valve is started, so even if the throttle valve is fully closed due to the release of the accelerator pedal, the intake pipe pressure downstream of the throttle valve will be substantially increased before the engine stops. At the same time, the exhaust gas remaining in the exhaust system during the valve overlap period in which both the intake and exhaust valves are open is prevented from flowing back to the intake system to prevent the next engine restartability from deteriorating. When the idle control valve is opened after the calibration at the fully closed position or for the calibration at the fully open position, the air having a high flow velocity flows from the bypass passage through the idle control valve. To prevent air from flowing downstream of the throttle valve,
Generation of unpleasant airflow noise can be prevented.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an overall view of an engine system. FIG. 2 is a circuit configuration diagram of an electronic control system. FIG. 3 is a flowchart of an ISC control routine. FIG. [Description of Signs] 1 Engine 7 Throttle valve 9 Bypass passage 10 Idle control valve 70 Electronic control unit (calibration operation control means) 81 Ignition switch

Continuation of front page    F term (reference) 3G065 AA04 AA11 CA26 DA07 DA15                       EA03 EA06 FA05 FA09 GA00                       GA01 GA09 GA11 GA16 GA41                 3G301 HA01 HA06 JA20 KA07 KA28                       LA04 LC04 NA08 NB03 NB06                       NB13 ND02 NE19 PA07Z                       PA10Z PA11Z PC08Z PD02Z                       PE01A PE03Z PF01Z PF13Z                       PF14Z PF16Z

Claims (1)

Claims 1. An engine idle control valve for calibrating a reference position of a step motor idle control valve interposed in a bypass passage that bypasses an upstream side and a downstream side of an engine throttle valve. A control device, comprising: a calibration operation control unit that, when an ignition switch is turned off, holds the idle control valve at a set opening degree or more for a set period, and thereafter starts a calibration operation of the idle control valve. A control device for an idle control valve of an engine.