JP2010053794A - Control device of internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To surely restrain racing of an engine speed in automatic starting, in a vehicle with an idle stop function separately mounted with a generator and a starter. <P>SOLUTION: The vehicle with the idle stop function is mounted with an alternator 33 and the starter 39, and automatically starts an engine by carrying an electric current to the starter 39 by setting power generation voltage of the alternator 33 to voltage (for example, the highest voltage of a controllable power generation voltage range) higher than preset voltage in manual starting when generating an automatic starting request in automatic stopping by an idle stop. With such a constitution, since load torque of the alternator 33 to the engine can be increased by increasing the power generation voltage of the alternator 33 before detecting completion of starting in automatic starting, the racing of the engine speed in the automatic starting can be surely restrained without delaying the timing for increasing the load torque of the alternator 33 in the automatic starting. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a control device for an internal combustion engine including an idle stop system that automatically stops and automatically starts an internal combustion engine (engine) serving as a drive source of a vehicle.

In recent years, vehicles equipped with an idle stop system (automatic stop / automatic starter) are increasing in order to satisfy increasingly demanding improvements in fuel consumption (CO ₂ reduction). Vehicles equipped with this idle stop system are frequently repeatedly automatically stopped and automatically started when driving in urban areas, etc. It has become an important technical issue in recent years.

Therefore, in the system described in Patent Document 1 (Japanese Patent Laid-Open No. 2004-156488), a motor generator that serves both as a generator and a starter (motor) is mounted on a vehicle, and a positive torque is applied to the motor generator during automatic start. The engine is cranked and self-ignited to start, and after completion of the start is detected, the motor generator armature phase terminals are short-circuited to generate negative torque in the motor generator. The engine rotation blow-up (engine speed overshoot) is suppressed.
Japanese Patent Application Laid-Open No. 2004-156488 (pages 2 to 3 etc.)

  However, in the configuration of the above-mentioned Patent Document 1, a positive torque is generated in the motor generator at the time of automatic start so that the engine is cranked and self-ignited to start, and after the start completion is detected, the motor generator is negatively charged. Is generated to suppress the engine rotation blow-up, so the negative timing is generated in the motor generator against the engine rotation blow-up that occurs instantaneously immediately after the first complete explosion at the time of automatic start. There is a possibility that the engine speed will not be sufficiently suppressed due to delay. Since the motor generator must operate as a starter that cranks the engine by generating a positive torque until the start completion is detected, the motor generator must generate a negative torque until the start completion is detected. Therefore, it is inevitable that the timing for generating the negative torque in the motor generator is delayed. In addition, the invention described in Patent Document 1 can be applied only to a vehicle on which a generator / starter motor generator is mounted, and not to a general vehicle on which a generator and a starter are mounted.

  The present invention has been made in consideration of these circumstances. Therefore, the object of the present invention is to ensure that the rotational speed of the internal combustion engine at the time of automatic start-up increases in a vehicle with an idle stop function, each equipped with a generator and a starter. An object of the present invention is to provide a control device for an internal combustion engine that can be suppressed to a low level.

  In order to achieve the above object, according to the first aspect of the present invention, there is provided an idle stop means for automatically stopping and automatically starting an internal combustion engine serving as a vehicle drive source, and an automatic start request is generated during the automatic stop by the idle stop means. An internal combustion engine comprising: a starter that cranks the internal combustion engine to automatically start the engine; a generator that is driven by the power of the internal combustion engine to generate power; and a control unit that controls a power generation voltage of the generator. In the control device, the control means controls the power generation voltage of the generator to be higher than that at the time of manual start by the automatic start so as to suppress an increase in the internal combustion engine rotation speed at the time of automatic start. .

  In this configuration, in a vehicle with an idle stop function, each equipped with a generator and a starter, the generator generated voltage is increased to increase the load torque of the generator with respect to the internal combustion engine before the start completion is detected at the time of automatic start. Therefore, the timing for increasing the load torque of the generator is not delayed, and the blow-up of the internal combustion engine rotation speed at the time of automatic start can be reliably suppressed by the load torque of the generator.

  In general, since the automatic start by the idle stop is started from the warm-up state, the startability is better than that at the time of the manual start starting from the cold state, and the internal combustion engine rotational speed is likely to increase. . In view of this point, the present invention reliably increases the rotational speed of the internal combustion engine by increasing the load torque (power generation voltage) of the generator with respect to the internal combustion engine before the completion of the start is detected during automatic start. However, for some reason (for example, a decrease in battery voltage), the driving force of the starter at the time of automatic start may be reduced. In such a case, when the load torque of the generator is large, the startability is deteriorated.

  As a countermeasure against this, as in claim 2, the internal combustion engine rotational increase speed is determined at the time of automatic start, and when the internal combustion engine rotational increase speed is slower than a predetermined value, the generated voltage of the generator is reduced or made zero. It is preferable to control. In short, because it is possible to determine whether the startability is good or bad depending on whether the internal combustion engine rotation speed is high or low at the time of automatic start, the internal combustion engine speed increase speed at the time of automatic start is slow and it is determined that the startability is poor In addition, if the generator voltage is immediately reduced or reduced to 0, the starter driving force is reduced for any reason and the generator load torque is reduced to ensure startability. can do.

  In the present invention, when determining the internal combustion engine rotation increase speed at the time of automatic start, the engine is started in a state where the power generation voltage of the generator is increased from the start of the automatic start than at the time of manual start. The generator power generation voltage may be reduced or reduced to 0, or the generator power generation voltage may be increased when the internal combustion engine rotational speed exceeds a predetermined value during automatic start. Thus, it is possible to suppress the increase in the internal combustion engine rotational speed, and to control so that the power generation voltage of the generator decreases or becomes zero when the internal combustion engine rotational increase speed is equal to or less than a predetermined value. In this case, it is not necessary to increase the generator voltage from the beginning of the automatic start compared to the time of manual start, or the generator is started with the generator voltage slightly increased from the start of the automatic start. Then, when the internal combustion engine rotational speed increases beyond a predetermined value, the power generation voltage of the generator may be further increased to suppress the internal combustion engine rotational speed from rising. In any case, it is possible to suppress the increase in the internal combustion engine rotation speed while ensuring the startability at the time of automatic start.

  Hereinafter, three Examples 1 to 3 embodying the best mode for carrying out the present invention will be described.

A first embodiment of the present invention will be described with reference to FIGS.
First, the overall configuration of the engine control system will be schematically described with reference to FIG.
A throttle valve 14 is provided in the middle of the intake pipe 13 connected to the intake port 12 of the engine 11, and the opening (throttle opening) of the throttle valve 14 is detected by a throttle opening sensor 15. The intake pipe 13 is provided with a bypass passage 16 that bypasses the throttle valve 14, and an idle speed control valve 17 is provided in the middle of the bypass passage 16. The bypass passage 16 and the idle speed control valve 17 may be omitted, and the idle rotation speed may be controlled by adjusting the intake air amount by adjusting the opening of the throttle valve 14 even during idling.

An intake pipe pressure sensor 18 for detecting the intake pipe pressure is provided on the downstream side of the throttle valve 14, and a fuel injection valve 19 is attached in the vicinity of the intake port 12 of each cylinder.
On the other hand, an exhaust gas purifying catalyst 22 is installed in the middle of the exhaust pipe 21 connected to the exhaust port 20 of the engine 11, and the exhaust gas air-fuel ratio or rich / lean is set upstream of the catalyst 22. An exhaust gas sensor 31 (air-fuel ratio or oxygen sensor or the like) for detection is provided.

  The cylinder block of the engine 11 is provided with a cooling water temperature sensor 23 that detects the cooling water temperature. A crank angle sensor 26 is installed opposite to the outer periphery of the signal rotor 25 attached to the crankshaft 24 of the engine 11, and a crank pulse signal is output from the crank angle sensor 26 at predetermined crank angles in synchronization with the rotation of the signal rotor 25. Is output, and the engine speed is detected based on the period (frequency) of the crank pulse signal.

  A cam angle sensor 29 is installed facing the outer periphery of the signal rotor 28 attached to the cam shaft 27 of the engine 11, and a cam pulse signal is output from the cam angle sensor 29 at a predetermined cam angle in synchronization with the rotation of the signal rotor 28. The cam angle reference position is detected based on the cam pulse signal, and the crank angle is detected from the count value by counting the crank pulse signal based on the cam angle reference position.

  Further, the rotation of the crank pulley 34 connected to the crankshaft 24 is transmitted to the alternator 33 (generator) via the belt 35, so that the alternator 33 is rotationally driven by the power of the engine 11 to generate electric power. ing. By controlling the field current of the alternator 33 by duty control or the like, the generated voltage (load torque) of the alternator 33 is controlled.

  On the other hand, as shown in FIG. 2, when the ignition switch 36 is switched from the OFF contact to the IG contact, power is supplied to the ECU 30 from a battery 37 mounted on the vehicle. Further, when the ignition switch 36 is switched from the IG contact to the ST contact, the drive coil 38a of the starter relay 38 is energized, the relay switch 38b is turned on and the starter 39 is energized, and the starter 39 rotates to rotate the engine 11. Crank and start.

  Outputs of various sensors such as the crank angle sensor 26 described above are input to an engine control circuit (hereinafter referred to as “ECU”) 30. The ECU 30 is mainly composed of a microcomputer, and controls the fuel injection amount and injection timing of the fuel injection valve 19 and the ignition timing of the spark plug 31 according to the engine operating state detected by various sensors.

  Further, the ECU 30 functions as an idle stop means in the claims, and automatically operates when a predetermined automatic stop condition (for example, accelerator fully closed, idle rotation, stopped, warm-up, etc.) is established during engine operation. When a stop request is generated, the engine 11 is stopped by stopping the combustion (ignition and / or fuel injection) of the engine 11 and the engine rotation is automatically stopped. When a start operation (for example, depression of an accelerator pedal) or a preparation operation for starting a vehicle (for example, release of a brake operation, shift operation to a shift range of a shift lever, etc.) occurs, an automatic start request is generated, The drive coil 38a of the starter relay 38 is energized, the relay switch 38b is turned on, and the starter 39 is energized, To automatically start the engine 11 by cranking motor 39 is rotated. During automatic stop, an automatic start request may be generated due to a request from auxiliary equipment (electric load) such as an air conditioner.

  Further, the ECU 30 plays a role as a control means for controlling the power generation voltage (load torque) of the alternator 33 by executing the alternator power generation voltage control program of FIG. The alternator power generation voltage control program of FIG. 3 is repeatedly executed at a predetermined cycle during the power-on period of the ECU 30.

  When this program is started, first, at step 101, it is determined whether or not it is an automatic start (whether or not an automatic start request is generated), and if it is determined that it is not an automatic start, the process proceeds to step 102. Then, the driver switches the ignition switch 36 to the ST contact, energizes the starter 39, and determines whether or not it is “manual start”. As a result, if it is determined that the engine is manually started, the process proceeds to step 104 where the power generation voltage of the alternator 33 is set to the set voltage at the time of manual start and the starter 39 is energized to start the engine 11. At this time, the set voltage at the time of manual start is set to a voltage lower than the set voltage at the time of automatic start described later.

  If it is determined in steps 101 and 102 that neither the automatic start nor the manual start is performed, the process proceeds to step 106, where the normal alternator power generation voltage control is executed, and the state of charge of the battery 37 and the electric load are determined. The power generation voltage of the alternator 33 is set in accordance with the power consumption and the like.

  On the other hand, if it is determined at the time of the above-mentioned step 101 that the automatic start is in progress, the process proceeds to step 103 where the power generation voltage of the alternator 33 is set to a voltage higher than the set voltage at the time of manual start (for example, the maximum voltage in the controllable power generation voltage range) The starter 39 is energized and the engine 11 is automatically started. In both cases of automatic start and manual start, in step 105, it is determined whether or not the engine speed has converged near the target idle speed, and until the engine speed has converged near the target idle speed, Continue generating voltage control during automatic start or manual start.

  Thereafter, when the engine speed has converged near the target idle speed, the routine proceeds to step 106 where normal alternator power generation voltage control is executed, and the alternator 33 according to the state of charge of the battery 37, the power consumption of the electric load, and the like. Set the generated voltage. Note that the normal alternator power generation voltage control may be executed after the power generation voltage control at the time of automatic start (manual start) is performed for a predetermined time.

  According to the first embodiment described above, as shown in FIG. 4, the power generation voltage of the alternator 33 is set to a voltage (for example, higher than a conventional set voltage) when an automatic start request is generated during automatic stop by idle stop. The starter 39 is energized and the engine 11 is automatically started.

  Conventionally, since the generated voltage of the alternator 33 at the time of automatic start is low and the load torque of the alternator 33 is small, the engine rotation speed has been increased at the time of automatic start. In order to increase the load torque of the alternator 33 with respect to the engine 11 by setting the power generation voltage of the alternator 33 to a voltage higher than the conventional one (for example, the highest voltage in the controllable power generation voltage range), The ascent can be reliably suppressed by the load torque of the alternator 33.

  As described above, in the first embodiment, in the vehicle with the idling stop function in which the alternator 33 and the starter 39 are mounted, the power generation voltage of the alternator 33 is increased to detect the engine 11 before the start completion is detected at the time of automatic start. Since the load torque of the alternator 33 can be increased, the timing of increasing the load torque of the alternator 33 is not delayed from the automatic start, and the engine torque speed at the time of automatic start is surely increased by the load torque of the alternator 33. Can be suppressed.

  In general, since the automatic start by the idle stop is started from the warm-up state, the startability is better than that at the manual start starting from the cold state, and the engine speed is likely to increase. In view of this point, the present invention increases the load torque (power generation voltage) of the alternator 33 with respect to the engine 11 and reliably suppresses the increase in engine rotation speed before detecting the completion of starting at the time of automatic starting. However, for some reason (for example, voltage drop of the battery 37), the driving force of the starter 39 at the time of automatic start may decrease. In such a case, if the load torque of the alternator 33 is large, the startability is deteriorated.

  As a countermeasure against this, in the second embodiment of the present invention, the alternator power generation voltage control program of FIG. 5 is executed, so that even if the driving force of the starter 39 at the time of automatic start is reduced for some reason, the starter 39 is started. We are trying to ensure sex. Hereinafter, processing contents of the alternator power generation voltage control program of FIG. 5 will be described.

  Also in the alternator power generation voltage control program of FIG. 5, the power generation voltage control (step 201 → 202 → 204 → 208 → 209) of the alternator 33 at the time of manual start is the same as that in the first embodiment.

  On the other hand, if it is determined in step 201 that the automatic start is in progress, the process proceeds to step 203, in which the power generation voltage of the alternator 33 is higher than the set voltage at the time of manual start (for example, the maximum voltage in the controllable power generation voltage range). And the starter 39 is energized to automatically start the engine 11. Thereafter, the process proceeds to step 205, where the engine speed increase rate (for example, the engine speed increase amount per calculation cycle) is calculated, and in the next step 206, the engine start is determined by whether the engine speed increase speed is slower than a predetermined value. Judge whether or not the nature is bad. As a result, if it is determined that the engine speed increase rate is slower than the predetermined value and the startability is poor, the process proceeds to step 207 and the power generation voltage of the alternator 33 is reduced. At this time, the power generation voltage of the alternator 33 may be decreased by a predetermined voltage, or may be decreased to a predetermined voltage (for example, the same voltage as that at the time of manual start), or the power generation voltage of the alternator 33 is reduced to 0. It is also good.

If it is determined in step 206 that the engine rotation speed is greater than or equal to a predetermined value, it is determined that the startability is good, and the power generation voltage of the alternator 33 at the beginning of automatic start is maintained as it is.
Thereafter, the process proceeds to step 208, where it is determined whether or not the engine rotational speed has converged near the target idle rotational speed, and the processing of steps 205 and 206 is performed until the engine rotational speed converges near the target idle rotational speed. If it is determined that the engine rotation speed is slower than the predetermined value and the startability is poor, the generated voltage of the alternator 33 is reduced.

  Thereafter, when the engine speed has converged near the target idle speed, the routine proceeds to step 209, where the normal alternator power generation voltage control is executed, and the alternator 33 is controlled according to the state of charge of the battery 37 and the power consumption of the electric load. Set the power generation voltage.

  According to the second embodiment described above, it is determined whether or not the startability is poor depending on whether or not the engine rotational speed at the time of automatic start is slow. Since the power generation voltage of 33 is reduced or set to 0, when the driving force of the starter 39 is reduced for any reason, the load torque of the alternator 33 with respect to the engine 11 is reduced to ensure startability. can do.

  In the second embodiment, the alternator 33 is started when the power generation voltage of the alternator 33 is increased from the beginning of the automatic start, and when it is determined that the engine rotation speed is slow and the startability is poor. However, in the third embodiment of the present invention, in step 201 → 203a of the alternator power generation voltage control program of FIG. The engine 11 is automatically started by energizing the starter 39 by setting the voltage (for example, the same voltage as that at the time of manual start or a voltage different from that).

  Thereafter, the process proceeds to step 205, where the engine speed increase rate (for example, the engine speed increase amount per calculation cycle) is calculated, and in the next step 206, the engine start is determined by whether the engine speed increase speed is slower than a predetermined value. Judge whether or not the nature is bad. As a result, if it is determined that the engine rotation speed is equal to or higher than the predetermined value and the startability is good, the process proceeds to step 207a and the power generation voltage of the alternator 33 is increased. At this time, the power generation voltage of the alternator 33 may be increased by a predetermined voltage, or may be increased to a predetermined voltage (for example, the highest voltage in the controllable power generation voltage range).

  On the other hand, if it is determined in step 206 that the engine rotation speed is slower than the predetermined value and the startability is poor, the process proceeds to step 207b, where the power generation voltage of the alternator 33 is reduced. At this time, the power generation voltage of the alternator 33 may be decreased by a predetermined voltage, or may be decreased to a predetermined voltage (for example, the same voltage as that at the time of manual start), or the power generation voltage of the alternator 33 is reduced to 0. It is also good.

  Thereafter, the process proceeds to step 208, and the processing of steps 205 to 207a or 207b is repeatedly executed at a predetermined period until the engine speed converges to the vicinity of the target idle speed, and the engine rotation speed increases at a predetermined value during automatic start. The generated voltage of the alternator 33 is increased or decreased depending on whether it is faster or slower. At this time, the “predetermined value” used as the determination threshold value in step 206 has hysteresis in order to prevent chattering in which the increase and decrease of the power generation voltage of the alternator 33 are frequently switched when the engine rotation speed is around the predetermined value. It is good to make it. Thereafter, when the engine speed has converged near the target idle speed, the routine proceeds to step 209, where the normal alternator power generation voltage control is executed, and the alternator 33 is controlled according to the state of charge of the battery 37 and the power consumption of the electric load. Set the power generation voltage.

  According to the third embodiment described above, since the power generation voltage (load torque) of the alternator 33 is increased or decreased depending on whether the engine rotation increasing speed is faster or slower than a predetermined value during automatic starting, automatic starting is performed. The engine speed can be suppressed from rising while ensuring the startability at the time.

  In the present invention, the engine control device (engine ECU) and the idle stop control device (idle stop ECU) may be configured by separate ECUs, or may be configured by one ECU.

It is a schematic block diagram of the whole engine control system in Example 1 of this invention. It is a circuit diagram which shows the electric constitution of a control system. It is a flowchart which shows the flow of a process of the alternator power generation voltage control program of Example 1. It is a time chart explaining an example of control which suppresses engine rotation blowing at the time of automatic starting. It is a flowchart which shows the flow of a process of the alternator power generation voltage control program of Example 2. It is a flowchart which shows the flow of a process of the alternator electric power generation voltage control program of Example 3.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 11 ... Engine (internal combustion engine), 13 ... Intake pipe, 14 ... Throttle valve, 19 ... Fuel injection valve, 21 ... Exhaust pipe, 26 ... Crank angle sensor, 29 ... Cam angle sensor, 30 ... ECU (control means, idle stop) Means), 33 ... alternator (generator), 37 ... battery, 38 ... starter relay, 39 ... starter

Claims (3)

Idle stop means for automatically stopping and automatically starting an internal combustion engine as a drive source of the vehicle;
A starter that cranks and automatically starts the internal combustion engine when an automatic start request occurs during automatic stop by the idle stop means;
A generator that is driven by the power of the internal combustion engine to generate electricity;
A control device for an internal combustion engine, comprising: a control means for controlling a power generation voltage of the generator;
The control means controls the internal combustion engine to suppress the increase in the rotational speed of the internal combustion engine at the time of automatic start by controlling the power generation voltage of the generator to be higher than at the time of manual start at the time of automatic start apparatus.   The control means determines an internal combustion engine rotation increase speed at the time of automatic start, and controls the generated voltage of the generator to be reduced or set to 0 when the internal combustion engine rotation increase speed is slower than a predetermined value. The control device for an internal combustion engine according to claim 1. Idle stop means for automatically stopping and automatically starting the internal combustion engine mounted on the vehicle;
A starter that cranks and automatically starts the internal combustion engine when an automatic start request occurs during automatic stop by the idle stop means;
A generator that is driven by the power of the internal combustion engine to generate electricity;
A control device for an internal combustion engine, comprising: a control means for controlling a power generation voltage of the generator;
The control means determines an internal combustion engine rotational speed increase at the time of automatic start, and suppresses an increase in the internal combustion engine rotational speed by increasing a power generation voltage of the generator when the internal combustion engine rotational speed exceeds a predetermined value. A control device for an internal combustion engine, characterized in that control is performed so that the generated voltage of the generator is reduced or reduced to zero when the rotational speed of the internal combustion engine is below a predetermined value.

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