JP2009203828A - Idle rotation speed control device of internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To inhibit generation of unburned HC due to variations of a power generation load on an alternator. <P>SOLUTION: During first idle including the time of engine start, at time T1, an electric current difference ΔA1 is calculated by comparing an ALT monitor electric current value and a reference electric current value. A correction value ΔNe1 is then calculated according to ΔA1, a target idle rotation speed Nset is calculated from ΔNe1 and a reference target idle rotation speed Nset0 and an intake air amount is controlled so that engine rotation speed reaches Nset. At time T2, an electric current difference ΔA2 is calculated and a correction value ΔNe2 is calculated according to this value. Nset is then calculated from ΔNe2 and Nset0 and control is performed similarly. At time T3, an electric current difference ΔA3 is calculated and a correction value ΔNe3 is calculated according to this value. Nset is then calculated from ΔNe3 and Nset0 and control is performed similarly. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an idle speed control device for an internal combustion engine that controls an intake air amount so that an engine speed becomes a target idle speed at the time of first idling including when the engine is started.

In Patent Document 1, in power generation control of an alternator driven by an internal combustion engine, power generation load applied to the internal combustion engine is reduced by stopping power generation of the alternator at a region where the exhaust emission concentration is high at the start of the engine and immediately after the start. By reducing the amount, an attempt is made to suppress the deterioration of exhaust emission at the time of starting the engine and immediately after starting.
JP 2004-72874 A

However, as described in Patent Document 1, if the power generation of the alternator is stopped at the start of the engine and immediately after the start, there are the following problems.
In order to perform feedback control of the exhaust air / fuel ratio immediately after the engine is started, it is necessary to activate the air / fuel ratio sensor for detecting the exhaust air / fuel ratio disposed in the exhaust passage at an early stage. However, when power generation of the alternator is stopped at the time of starting the engine and immediately after starting, the required power of the heater provided in the sensor cannot be ensured for activating the sensor. For this reason, the activation of the sensor is delayed, and there is a problem that it takes time from the start of the engine to the start of exhaust air / fuel ratio feedback control.

  Further, in the conventional idling engine speed control of the internal combustion engine, the engine speed is controlled to be fixed at the target engine speed from the start of the engine to the time of the first idling, and thus there are the following problems.

  During the idle speed control (target rotation fixing control), if the battery charge amount immediately before the engine start is reduced or the battery is deteriorated, the power generation load of the alternator increases. At this time, since the engine speed is fixedly controlled at the target speed, the generator load and the intake pressure (boost pressure) increase and the intake negative pressure decreases as the power generation load of the alternator increases. FIG. 11 shows this relationship. FIG. 11 shows the relationship between the intake pressure (boost pressure) during idle speed control and the generated current value (ALT generated current value) of the alternator. This figure shows that the intake pressure (boost pressure) increases as the power generation current value of the alternator increases (the power generation request increases) due to the decrease or deterioration of the charge amount of the battery.

  In general, the higher the intake pressure (boost pressure), the higher the unburned HC concentration in the exhaust gas and the greater the unburned HC amount (see FIG. 12). This is because as the intake pressure (boost pressure) increases, the intake negative pressure decreases, the atomization of the fuel supplied to the internal combustion engine is not promoted, and the unburned fuel increases.

  FIG. 13 summarizes the relationship between FIG. 11 and FIG. 12 described above. FIG. 13 shows the relationship between the power generation current value (ALT power generation current value) of the alternator and the unburned HC concentration / unburned HC amount in the exhaust during idle speed control (target rotation fixed control). This figure shows that the unburned HC concentration in the exhaust gas increases and the unburned HC amount increases as the power generation current value of the alternator increases due to the decrease or deterioration of the battery charge (the power generation requirement increases). Show. In other words, when the conventional idle speed control (target rotation fixed control) is performed, the intake pressure (boost pressure) increases when the power generation demand of the alternator increases due to a decrease or deterioration of the charge amount of the battery, and the exhaust emission is reduced. There is a problem of getting worse.

  Furthermore, in recent years, when the vehicle decelerates, the alternator converts the kinetic energy of the traveling vehicle into electrical energy and stores it in the battery. In order to perform control (alternator cooperative control) to reduce the battery, a battery that is easily charged and discharged is employed. Since this type of battery tends to absorb the generated current of the alternator when the engine is started, the power generation load of the alternator is likely to increase when the engine is started. For this reason, since the intake pressure (boost pressure) tends to be high when the engine is started, there is a problem that the exhaust emission is likely to deteriorate when the engine is started.

  In view of the above-described problems, the present invention provides exhaust due to variations in the power generation load of the alternator when the intake air amount is controlled so that the engine rotational speed becomes the target idle rotational speed at the time of first idle including when the engine is started. The purpose is to suppress the deterioration of emissions.

  For this reason, in the present invention, the current generated by the alternator driven by the internal combustion engine when the intake air amount is controlled so that the engine speed becomes the target idle speed at the time of first idling including when the engine is started. A value is detected, the detected generated current value is compared with a reference value of the generated current at the time of the first idle, a current deviation is calculated, and the target idle speed is increased or decreased according to the calculated current deviation.

  According to the present invention, at the time of fast idling including when the engine is started, the target idle speed is increased or decreased according to the generated current of the alternator, so that the variation in the power generation load of the alternator is absorbed by the increase or decrease of the engine speed. Since variation in atmospheric pressure (boost pressure) can be suppressed, deterioration of exhaust emission can be suppressed.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a configuration diagram of an internal combustion engine showing an embodiment of the present invention.
An electric throttle valve 2 is disposed in the intake passage 1 of the internal combustion engine. The opening degree of the electric throttle valve 2 is controlled by an output signal from an engine control unit (ECU) 3, thereby controlling the intake air amount.

  An electromagnetic fuel injection valve 4 is provided so as to inject fuel into the intake passage 1 (intake port) on the downstream side of the electric throttle valve 2. The fuel injection valve 4 is energized to open a solenoid by an injection pulse signal output from the ECU 3 in synchronization with engine rotation, and injects fuel adjusted to a predetermined pressure. The fuel injection valve 4 may be arranged so as to inject fuel directly into the combustion chamber of the internal combustion engine in addition to being arranged so as to inject fuel into the intake port.

On the other hand, the electrical load 5 is connected to the battery 6.
Further, an alternator 7 driven by the internal combustion engine is provided, and the battery 6 can be charged by the alternator 7 and the electric load 5 can be directly fed.

Here, the alternator 7 is equipped with an ammeter (alternator generated current detection means) 8 for detecting the generated current, and the signal is input to the ECU 3.
In addition, an accelerator opening signal APO is input to the ECU 3 from an accelerator opening sensor (not shown) that detects the amount of depression of the accelerator pedal (accelerator opening). A crank angle signal is input from a crank angle sensor 9 that detects rotation of the output shaft of the internal combustion engine. The engine speed Ne can be calculated from the crank angle signal. A cooling water temperature signal Tw is input from a water temperature sensor (not shown) attached to the internal combustion engine.

  Further, the ECU 3 includes, as software, current deviation calculation means for calculating a current deviation by comparing the generated current value detected by the ammeter 8 with a reference value of the generated current at the time of the first idle, and the calculated current deviation. And a target idle speed correcting means for correcting the target idle speed to be increased or decreased according to the above.

  The ECU 3 performs calculations for various types of control of the internal combustion engine. Here, in particular, the generator current value of the alternator is controlled in order to control the idle rotation speed in accordance with the generator current value of the alternator during fast idling including when the engine is started. Is compared with the reference value of the generated current at the time of first idling, and the current deviation is calculated, and based on this, the target idle speed is increased or decreased, and the electric power is adjusted so that the engine speed becomes the corrected target idle speed. The intake air amount is controlled by the throttle valve 2.

Next, the control concept of the idle speed control of the internal combustion engine in the present invention will be described with reference to FIGS.
FIG. 2 shows the engine speed, the intake pressure (boost pressure), the power generation amount required for the alternator (ALT required power generation amount), the unburned HC concentration in the exhaust gas, and the unburned HC when the internal combustion engine is started continuously. The relationship with quantity is shown. The solid line in the figure indicates the ALT required power generation amount, and the higher the ALT required power generation amount, the higher the rotation speed / high intake pressure (high boost pressure) side. The dotted lines in the figure indicate the unburned HC concentration and the unburned HC amount in the exhaust gas. The higher the intake pressure (boost pressure), the higher the unburned HC concentration and the greater the unburned HC amount. This is because, as described above, the higher the intake pressure (boost pressure), the lower the intake negative pressure, the more the fuel supplied to the internal combustion engine is not promoted, and the unburned fuel increases.

  In an internal combustion engine that can be started at the ALT required power generation amount A (black circle in the figure) during normal times, if the ALT required power generation amount increases due to a decrease or deterioration in the battery charge amount, the conventional idle speed control (target rotation) In (fixed control), the intake pressure (boost pressure) rises while the engine speed is fixed and moves to the ALT required power generation amount B (white circle in the figure), so the unburned HC concentration in the exhaust becomes high. At the same time, the amount of unburned HC increases. Therefore, in the idle speed control in the present invention, when the ALT required power generation amount increases, the engine speed is increased, and the unburned HC concentration and the unburned HC amount in the exhaust gas are changed to the ALT required power generation amount A (black circle mark in the figure). ) Is controlled so as to move to the ALT required power generation amount C (white square mark in the figure) equivalent to.

  Here, when the ALT required power generation amount increases during idle speed control, the engine speed is increased, and the ALT required power generation amount A (black circle mark in FIG. 2) to the ALT required power generation amount C (white square mark in FIG. 2). The reason why it is possible to move to) will be described with reference to FIG.

  FIG. 3 is a diagram showing the output characteristics of the alternator (a diagram showing the relationship between the rotational speed of the alternator and the torque). This figure shows that when the alternator rotational speed is constant, the torque required for power generation (ALT torque) increases as the power generation amount required for the alternator (ALT required power generation amount) increases. Moreover, this figure shows that when the ALT required power generation amount is constant, the efficiency increases as the alternator rotational speed becomes higher than the rotational speed at which the alternator torque becomes maximum (the rotational speed indicated by the dotted line in the figure). It shows that the ALT torque decreases. Therefore, when the ALT required power generation amount increases, the ALT required power generation amount A (the black circle in the figure) is increased by increasing the engine speed and the alternator speed while keeping the ALT torque substantially constant. It becomes possible to move to C (white square mark in the figure).

Next, idle speed control of the internal combustion engine in the present embodiment will be described based on FIGS.
FIG. 4 is a time chart of the alternator power generation current value and the engine speed during idle speed control in this embodiment, FIGS. 5 to 7 are flowcharts showing idle speed control in this embodiment, and FIG. 8 is in this embodiment. FIG. 9 is a flowchart showing the throttle control according to the present embodiment, FIG. 10 is a flowchart showing the throttle control in the present embodiment, and FIG. 10 is a graph showing the relationship between the rotational speed, torque and generated current value of the alternator during idle speed control in the present embodiment. It is a figure which shows transition.

  FIG. 4A is a time chart of the alternator power generation current value at the time of idle speed control. In this chart, a dotted line X indicates a reference value of the generated current at the time of first idling. This reference current value is a time series model of the current value of the alternator under a central condition in which the state of charge of the battery (SOC state), the soak time (time from the stop of the operation of the internal combustion engine to the restart), etc. are predetermined. , Stored in advance in the current deviation calculation means of the ECU 3. Further, in this chart, a solid line Y indicates an actually measured value (ALT monitor current value) of the generator current generated by the alternator detected by the ammeter 8 described above.

  In the present embodiment, the ALT monitor current value (solid line Y) and the reference current value (dotted line X) are compared three times (time T1, T2, T3) after the engine is started, and the current deviation provided in the ECU 3 is calculated. The current deviation (ΔA1, ΔA2, ΔA3) is calculated by the means. Here, at time T1, both the ALT monitor current value (solid line Y) and the reference current value (dotted line X) are maximized, and the engine speed is also maximized. The engine speed at this time is called the peak speed. Time T2 is after a predetermined time such as a calculation period has elapsed from time T1. Time T3 is after the engine speed has converged to the target idle speed. Whether or not the engine speed has converged to the target idle speed is determined, for example, by whether or not the engine speed is within ± 5% of the target idle speed.

  FIG. 4B is a time chart of the engine speed at the time of idle speed control. In this chart, the dotted line X ′ indicates the engine speed under the above-described central condition, and the thin solid line Y ′ indicates the actual value of the engine speed. In this chart, the alternate long and short dash line indicates the reference target idle speed Nset0 with the cooling water temperature Tw as a parameter, and the thick solid line indicates the target idle speed Nset after correcting the reference target idle speed Nset0. ing. Here, the target idle speed Nset is calculated by the following equation.

Nset = Nset0 + ΔNe (1)
Here, ΔNe is a correction value for increasing / decreasing the reference target idle rotational speed Nset0, and the target idle rotational speed correcting means provided in the ECU 3 according to the current deviation (ΔA1, ΔA2, ΔA3) described above. Is calculated by That is, at time T1, the correction value ΔNe1 is calculated according to the current deviation ΔA1. At time T2, a correction value ΔNe2 is calculated according to the current deviation ΔA2. At time T3, a correction value ΔNe3 is calculated according to the current deviation ΔA3. The calculation method of these correction values ΔNe1 to ΔNe3 will be described in the flow of idle speed control (FIGS. 5 to 8) described later.

Next, the flow of idle speed control in the present embodiment will be described with reference to FIGS.
First, in step S1 of FIG. 5, the ECU 3 detects the ALT monitor current value Ap and the peak rotational speed Np at time T1 after the engine is started (see FIG. 4). Thereafter, in step S2, it is determined whether or not the peak rotational speed Np is larger than a predetermined value Np1, and whether or not the ALT monitor current value Ap is smaller than a predetermined value Ap1. Here, the predetermined value Np1 is the peak rotational speed under the above-described central condition (see FIG. 4B). The predetermined value Ap1 is a reference current value (Alt current value under the central condition) at time T1 (see FIG. 4A). In step S2, if the peak rotational speed Np is larger than the predetermined value Np1, or if the ALT monitor current value Ap is smaller than the predetermined value Ap1, the process proceeds to step S3. When the process proceeds to step S3, since the power generation load of the alternator is small, the influence of the power generation of the alternator on the exhaust emission is relatively small. Therefore, the target idle speed is not corrected according to the power generation current of the alternator. For this reason, after calculating the target idle speed Nset ′ based on the cooling water temperature Tw in step S3, the engine speed is controlled based on this calculation result in step S4 according to the flow shown in FIG. The intake air amount is controlled so that Ne becomes the target idle speed Nset ′. Note that FIG. 9 will be described later.

  On the other hand, when the peak rotational speed Np is not more than the predetermined value Np1 and the ALT monitor current value Ap is not less than the predetermined value Ap1 in step S2, the process proceeds to step S5. In the case of proceeding to step S5, since the power generation load of the alternator is large, the influence of the power generation of the alternator on the exhaust emission is relatively large. Therefore, the target idle speed is corrected according to the power generation current of the alternator.

  After calculating the reference target idle speed Nset0 based on the coolant temperature Tw in step S5, the process proceeds to step S6 to calculate the current deviation ΔA1 at time T1 (see FIG. 4A).

  After calculating the current deviation ΔA1 in step S6, in step S7, based on the relationship diagram between the current deviation ΔA (ΔA1 to ΔA3) and the correction values ΔNe1 to ΔNe3 shown in FIG. It is determined whether or not it is larger. In this embodiment, in FIG. 8, the correction value ΔNe when the current deviation ΔA is 0 or more is set in advance. However, the present invention is not limited to this, and the correction value ΔNe when the current deviation ΔA is a negative value. Can also be set in advance.

In the present embodiment, the correction value ΔNe is increased as the detected value of the generated current is larger than the reference value (the current deviation ΔA is larger) (see FIG. 8).
In the present embodiment, the predetermined value ALTuplmt is set to the upper limit value of the current deviation ΔA shown in FIG.

  When the current deviation ΔA1 is larger than the predetermined value ALTuplmt in step S7, the process proceeds to step S8, and the ECU 3 performs control to reduce the generated voltage of the alternator. At this time, the correction value ΔNe1 is not calculated, and the target idle speed is kept at the current value, and the process proceeds to step S12 in FIG.

  On the other hand, if the current deviation ΔA1 is equal to or smaller than the predetermined value ALTuplmt in step S7, the process proceeds to step S9, and the correction value ΔNe1 is calculated based on the current deviation ΔA1 using FIG. Thereafter, in step S10, the reference target idle speed Nset0 calculated in step S5 and the correction value ΔNe1 calculated in step S9 are substituted into the above equation (1), and the corrected target idle speed is set. Nset is calculated, and the process proceeds to step S11. In step S11, the intake air amount is controlled so that the engine rotational speed Ne becomes the target idle rotational speed Nset by performing throttle control according to the flow of FIG. 9 described later based on the calculated corrected target idle rotational speed Nset. To do.

Thereafter, the process proceeds to step S12 in FIG. 6, and the ALT monitor current value at time T2 is detected.
Thereafter, in step S13, a current deviation ΔA2 at time T2 is calculated (see FIG. 4A).

  After calculating the current deviation ΔA2 in step S13, in step S14, the current deviation ΔA2 is predetermined based on the relationship diagram between the current deviation ΔA (ΔA1 to ΔA3) and the correction values ΔNe1 to ΔNe3 shown in FIG. It is determined whether or not the value is greater than ALTuplmt.

  If the current deviation ΔA2 is greater than the predetermined value ALTuplmt in step S14, the process proceeds to step S15, and the ECU 3 performs control to reduce the power generation voltage of the alternator. At this time, the correction value ΔNe2 is not calculated, the target idle speed is kept at the current value, and the process proceeds to step S19 in FIG.

  On the other hand, if the current deviation ΔA2 is equal to or smaller than the predetermined value ALTuplmt in step S14, the process proceeds to step S16, and the correction value ΔNe2 is calculated based on the current deviation ΔA2 using FIG. Thereafter, in step S17, the reference target idle speed Nset0 calculated in step S5 and the correction value ΔNe2 calculated in step S16 are substituted into the above equation (1), and the corrected target idle speed is set. Nset is calculated, and the process proceeds to step S18. In step S18, the intake air amount is controlled so that the engine rotational speed Ne becomes the target idle rotational speed Nset by performing throttle control according to the flow of FIG. 9 described later based on the calculated corrected target idle rotational speed Nset. To do.

Thereafter, the process proceeds to step S19 in FIG. 7, and the ALT monitor current value at time T3 is detected.
Thereafter, in step S20, a current deviation ΔA3 at time T3 is calculated (see FIG. 4A).

  After calculating the current deviation ΔA3 in step S20, in step S21, the current deviation ΔA3 is predetermined based on the relationship diagram between the current deviation ΔA (ΔA1 to ΔA3) and the correction values ΔNe1 to ΔNe3 shown in FIG. It is determined whether or not the value is greater than ALTuplmt.

  If the current deviation ΔA3 is larger than the predetermined value ALTuplmt in step S21, the process proceeds to step S22, and the ECU 3 performs control to reduce the power generation voltage of the alternator. At this time, the correction value ΔNe3 is not calculated, and the target idle speed keeps the current value.

  On the other hand, if the current deviation ΔA3 is equal to or smaller than the predetermined value ALTuplmt in step S21, the process proceeds to step S23, and the correction value ΔNe3 is calculated based on the current deviation ΔA3 using FIG. Thereafter, in step S24, the reference target idle speed Nset0 calculated in step S5 and the correction value ΔNe3 calculated in step S23 are substituted into the above equation (1), and the corrected target idle speed is set. Nset is calculated, and the process proceeds to step S25. In step S25, the intake air amount is controlled so that the engine rotational speed Ne becomes the target idle rotational speed Nset by performing throttle control according to the flow of FIG. 9 described later based on the calculated corrected target idle rotational speed Nset. To do.

Next, the flow of throttle control executed in step S4 in FIG. 5, step S11, step S18 in FIG. 6, and step S25 in FIG. 7 will be described based on FIG.
In step S31, the ECU 3 first calculates the required air amount based on the accelerator opening signal APO of the accelerator opening sensor.

  Thereafter, in step S32, it is determined whether or not an idle speed feedback condition (F / B condition) is satisfied. Specifically, it is determined whether or not the vehicle speed is equal to or less than a predetermined value during idling when the accelerator opening signal APO = 0.

If it is a feedback control condition, the process proceeds to step S33.
In step S33, the engine speed Ne is detected.
Thereafter, in step S34, the engine speed Ne is compared with the above-described target idle speed Nset (or Nset ′). If the engine speed Ne is smaller than the target idle speed Nset, the process proceeds to step S35 and feedback is performed. Increase the air amount (F / B air amount). Conversely, if the engine speed Ne is greater than the target idle speed Nset, the routine proceeds to step S36, where the feedback air amount (F / B air amount) is decreased.

On the other hand, when it is not the feedback control condition, the current value is held without increasing / decreasing the feedback air amount (F / B air amount).
After these, the process proceeds to step S37.

In step S37, the idle air amount is calculated by the following equation based on the feedback air amount (F / B air amount) increased or decreased in steps S35 and S36.
Idle air volume = Basic idle air volume + F / B air volume (2)
Here, the basic idle air amount is set based on the above-described target idle rotation speed Nset (or Nset ′).

  Thereafter, in step S38, the target throttle opening (target TVO) of the electric throttle valve 2 is calculated based on the sum of the required air amount calculated in step S31 and the idle air amount calculated in step S37. Then, by controlling the throttle with this target TVO, the intake air amount is controlled.

  As described above, the idle speed control flow shown in FIGS. 5 to 7 and the throttle control flow shown in FIG. 9 are executed, and the idle generator current value and engine speed time chart shown in FIG. Transition of the alternator rotation speed, torque, and generated current value when the rotation speed control is performed will be described with reference to FIG.

  In this figure, the dotted line corresponds to the reference current value X in FIG. The solid line corresponds to the ALT monitor current value Y in FIG. Also, the black circles in the figure indicate changes in the reference current value X at times T1, T2, and T3, and the white squares in the figure indicate changes in the ALT monitor current value Y at times T1, T2, and T3. Yes.

  This figure shows that when the difference between the measured value of the alternator torque (power generation load) at time T1 and the reference value is generated, the torque of the alternator (at time T3) is controlled by performing the above-described idle speed control. It shows that the difference between the measured value of the power generation load) and the reference value is decreasing. In other words, even if the alternator power generation load at the time of engine start increases due to a decrease or deterioration of the charge amount of the battery, if the engine speed converges to the target idle speed, the increase in power generation load at the time of engine start is Absorbs by increasing the number. As a result, even if the power generation load at the time of starting the engine increases, when the engine speed converges to the target idle speed, the intake pressure (boost pressure) hardly changes, so it is possible to suppress the deterioration of exhaust emission. become.

  According to the present embodiment, the alternator power generation current detecting means (ammeter 8) for detecting the current value generated by the alternator driven by the internal combustion engine, and the detected power generation current value of the generated current at the time of the first idle. Current deviation calculating means (step S6, step S13, step S20) for calculating the current deviation (ΔA) compared with the reference value, and the target idle speed (Nset) is increased or decreased according to the calculated current deviation (ΔA). By providing the target idle speed correction means (step S10, step S17, step S24) for correction (ΔNe), the variation in the power generation load of the alternator is absorbed by the increase or decrease of the engine speed at the time of the first idle including when the engine is started. This makes it possible to suppress variations in intake pressure (boost pressure). For this reason, deterioration of exhaust emission can be suppressed.

  In addition, according to the present embodiment, the current deviation calculating means (step S6, step S13, step S20) has the reference value of the generated current at the time of the first idle as a time series model, and at a plurality of points on the time axis. Thus, the current deviation is calculated, so that it is possible to accurately control the idling speed according to the variation in the power generation load of the alternator.

  Further, according to the present embodiment, the target idle speed correction means (step S10, step S17, step S24) performs correction to increase the target idle speed (Nset) as the generated current detection value is larger than the reference value. Therefore, even if the power generation load of the alternator increases due to a decrease or deterioration of the charge amount of the battery, it is possible to suppress an increase in the intake pressure (boost pressure), thereby suppressing the generation of unburned HC. it can.

  Further, according to the present embodiment, when the current deviation (ΔA) is larger than the predetermined value (ALTuplmt), the engine speed is reduced by performing the control (step S8, step S15, step S22) for reducing the generated voltage of the alternator. Since it is possible to prevent the number from changing sharply, it is possible to prevent the driver from feeling uncomfortable in driving feeling. Further, it is possible to prevent an increase in the amount of unburned HC due to an increase in intake pressure (boost pressure) due to a sharp increase in engine speed.

  Further, according to the present embodiment, at the time of the first idling, when the maximum value (Np) of the engine speed is larger than the predetermined value (Np1), or the current value (Ap) generated by the alternator is the predetermined value (Ap1). If the power generation load of the alternator is small, the engine is highly efficient by not correcting the target idle speed (Nset) by the target idle speed correction means (step S10, step S17, step S24). Driving can be realized.

  In the present embodiment, the current deviation ΔA is calculated three times at the time of the first idle. However, the number of calculations is not limited to this. For example, the current deviation ΔA is sequentially calculated according to the calculation cycle of the ECU 3. May be.

The block diagram of the internal combustion engine which shows one Embodiment of this invention The figure which shows the relationship between the engine speed, the intake pressure, the alternator demand power generation amount, and the unburned HC concentration / amount when the internal combustion engine is continuously started Diagram showing the relationship between alternator speed and torque Time chart of alternator power generation current value and engine speed during idle speed control Diagram showing part of the flow for idle speed control Diagram showing part of the flow for idle speed control Diagram showing part of the flow for idle speed control Diagram showing the relationship between current deviation and correction value Throttle control flowchart The figure which shows transition of the rotation speed of the alternator at the time of idle rotation speed control, torque, and generated current value The figure which shows the relationship between the intake pressure at the time of the conventional idle speed control, and the generator electric current value of an alternator Diagram showing the relationship between intake pressure and unburned HC concentration / volume The figure which shows the relationship between the electric power generation current value of the alternator at the time of the conventional idle speed control, and unburned HC concentration and quantity

Explanation of symbols

1 Intake passage 2 Electric throttle valve 3 Engine control unit (ECU)
4 Fuel Injection Valve 5 Electric Load 6 Battery 7 Alternator 8 Ammeter (Alternator Generated Current Detection Means)
9 Crank angle sensor

Claims (5)

In an idling engine speed control device for an internal combustion engine that controls the amount of intake air so that the engine speed becomes a target idling engine speed during fast idling including when the engine is started,
An alternator power generation current detecting means for detecting a current value generated by an alternator driven by the internal combustion engine;
A current deviation calculating means for calculating a current deviation by comparing the detected generated current value with a reference value of the generated current at the time of first idling;
An idle speed control device for an internal combustion engine, comprising: target idle speed correction means for increasing or decreasing the target idle speed in accordance with the calculated current deviation.   2. The internal combustion engine according to claim 1, wherein the current deviation calculation means has a reference value of the generated current at the time of first idling as a time series model, and calculates the current deviation at a plurality of points on the time axis. Engine idle speed control device.   3. The idle rotation of the internal combustion engine according to claim 1, wherein the target idle speed correction means performs a correction to increase the target idle speed as the detected value of the generated current is larger than a reference value. Number control device.   The idle speed control device for an internal combustion engine according to any one of claims 1 to 3, wherein when the current deviation is larger than a predetermined value, control is performed to reduce the generated voltage of the alternator. .   At the time of the first idle, when the maximum value of the engine speed is larger than a predetermined value, or when the current value generated by the alternator is smaller than the predetermined value, the target idle speed correction means by the target idle speed correction means The idle speed control device for an internal combustion engine according to any one of claims 1 to 4, wherein correction is not performed.

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