JP4844516B2 - Internal combustion engine control system - Google Patents

Description

The present invention, at the start of the internal combustion engine, relates to an internal combustion engine control system provided with a luer Idoringu period predicted equipment to predict the length of the immediately following idle period.

  When the internal combustion engine is cold started, it is necessary to raise the temperature of the exhaust purification catalyst provided in the exhaust passage and to activate the exhaust purification catalyst earlier. Therefore, immediately after starting the internal combustion engine, during the idling period in which the operating state of the internal combustion engine is in the idling state, the ignition timing of the internal combustion engine is retarded from the basic ignition timing and the intake air amount of the internal combustion engine is reduced. A technique for increasing the basic air amount is known.

  When the ignition timing is retarded, the temperature of the exhaust gas increases, so that the temperature of the exhaust purification catalyst can be raised more quickly. In addition, if the ignition timing is retarded during the idling period, the output torque of the internal combustion engine is reduced, so that the idling speed that is the engine speed during the idling period may be reduced and the value may become unstable. is there. However, it is possible to suppress a decrease in the idling speed by increasing the intake air amount.

  Therefore, according to the above technique, it is possible to activate the exhaust purification catalyst while suppressing the idling speed from becoming unstable during the idling period immediately after the start of the internal combustion engine.

  Patent Document 1 describes a technique for reducing the retard amount in accordance with the elapsed time from the start of the internal combustion engine when retarding the ignition timing during the idling period.

  As described above, when the ignition timing is retarded during the idling period, the temperature increase of the exhaust purification catalyst can be further promoted by increasing the retard amount. However, if the ignition timing is retarded excessively, the unburned fuel component in the exhaust increases, so that the unburned fuel component that flows out downstream from the exhaust purification catalyst during the temperature rise of the exhaust purification catalyst (hereinafter referred to as the outflow). The amount of the fuel component) may increase. As a result, there is a possibility that the integrated amount of the outflow fuel component during the idling period increases excessively. On the other hand, if the exhaust purification catalyst is not sufficiently heated during the idling period, it becomes difficult to sufficiently suppress the amount of the outflow fuel component immediately after the end of the idling period.

  However, if it is impossible to predict the length of the idling period immediately after starting the internal combustion engine, the integrated amount of the outflow fuel component during the idling period with respect to the retard amount of the ignition timing and the exhaust purification at the end of the idling period It is difficult to predict the temperature of the catalyst.

Further, even when the retard amount of the ignition timing is changed according to the elapsed time from the starting time of the internal combustion engine as in the cited document 1, the retard amount of the ignition timing is constant regardless of the length of the idling period. If the ratio is changed, it is difficult to control the integrated amount of the outflow fuel component during the idling period and the temperature of the exhaust purification catalyst at the end of the idling period to suitable values.
JP-A-6-26432 JP-A-2-291458 JP 2004-218558 A JP 2007-71113 A

  An object of the present invention is to provide a technique capable of predicting the length of an idling period immediately after an internal combustion engine is started.

  The present invention predicts the length of the current idling period based on the length of the past idling period when the internal combustion engine is started.

More specifically, the idling period predicting device for an internal combustion engine according to the present invention is:
Measuring means for measuring the length of an idling period, which is a period in which the operating state of the internal combustion engine is in an idling state immediately after starting the internal combustion engine;
Storage means for storing the length of the idling period measured by the measurement means;
Prediction means for predicting the length of the current idling period based on the length of past idling periods for a plurality of times stored in the storage means when the internal combustion engine is started. To do.

  According to the present invention, when the internal combustion engine is started, the length of the idling period immediately after that can be predicted.

  In the present invention, engine temperature acquisition means for acquiring the engine temperature at the start of the internal combustion engine may be further provided. In this case, the storage unit stores the length of the idling period measured by the measurement unit in association with the engine temperature acquired by the engine temperature acquisition unit. The predicting means determines the engine temperature acquired at this time by the engine temperature acquiring means when the engine temperature corresponding to the corresponding idling period stored in the storage means is started. A plurality of items within a predetermined range are selected. Further, the predicting means predicts the length of the current idling period based on the lengths of the selected idling periods for a plurality of times.

  The length of the idling period tends to change according to the engine temperature at the start of the internal combustion engine. Therefore, according to the above, when the internal combustion engine is started, the length of the idling period immediately after that can be predicted with higher accuracy.

  In the present invention, the predicting means may use the representative value of the length of the past idling period for the predetermined number of times stored in the storage means as the predicted value of the length of the idling period.

  Here, the predetermined number of times is the number of times that it can be determined that the length of the idling period can be predicted with sufficient accuracy. The representative value may be any value such as an average value, a maximum value, a minimum value, or a mode value.

  Further, when the internal combustion engine is cold-started, the temperature of the exhaust purification catalyst provided in the exhaust passage of the internal combustion engine is increased by retarding the ignition timing of the internal combustion engine from the basic ignition timing during the idling period. The idling period prediction device for an internal combustion engine according to the present invention may be applied to an internal combustion engine control system provided with a temperature means.

  Here, the basic ignition timing is a value determined as the ignition timing when it is not necessary to raise the temperature of the exhaust purification catalyst during the idling period.

If the length of the idling period can be predicted when the internal combustion engine is started, the temperature of the exhaust purification catalyst at the end of the idling period and the outflow during the idling period when the ignition timing is retarded during the idling period The integrated amount of the fuel component can be estimated based on the predicted value.

  Therefore, in the above case, the temperature raising means controls the ignition timing during the idling period based on the length of the idling period predicted by the idling period prediction device.

  This makes it possible to more suitably control the temperature of the exhaust purification catalyst at the end of the idling period and the integrated amount of the outflow fuel component during the idling period.

  For example, the temperature raising means is configured so that the accumulated amount of the outflow fuel component during the idling period is minimized so that the temperature of the exhaust purification catalyst at the end of the idling period is equal to or higher than a predetermined activation temperature. The ignition timing during the idling period may be controlled based on the length of the idling period predicted by the prediction device.

  Here, the predetermined activation temperature is a value by which it can be determined that the amount of the outflow fuel component is within the allowable range if the temperature of the exhaust purification catalyst is equal to or higher than the predetermined activation temperature. This predetermined activation temperature is predetermined based on experiments and the like.

  As a result, both the accumulated amount of the spilled fuel component during the idling period and the amount of the spilled fuel component immediately after the end of the idling period can be reduced as much as possible.

  Further, when the ignition timing during the idling period is retarded from the basic ignition timing by the temperature raising means, the intake air amount of the internal combustion engine during the idling period may be increased from the basic air amount.

  Here, the basic air amount is determined as a value capable of setting the idling speed to the target value by controlling the intake air amount to the basic air amount during the idling period if the ignition timing is the basic time. It has been.

  According to this, it is possible to suppress a decrease in the idle speed.

  When the internal combustion engine is cold started, the temperature of the exhaust purification catalyst provided in the exhaust passage of the internal combustion engine is raised by controlling the ignition timing, intake air amount, and fuel injection amount of the internal combustion engine during the idling period. The idling period prediction device for an internal combustion engine according to the present invention may be applied to an internal combustion engine control system provided with a temperature raising means.

  The temperature of the exhaust purification catalyst and the amount of the outflow fuel component during the idling period are correlated not only with the ignition timing but also with the intake air amount and the fuel injection amount. Therefore, the temperature raising means according to the control system of the internal combustion engine raises the temperature of the exhaust purification catalyst by controlling the ignition timing, the intake air amount, and the fuel injection amount.

  In this case, when the length of the idling period can be predicted at the start of the internal combustion engine, the idling period when the ignition timing, the intake air amount, and the fuel injection amount are changed during the idling period ends. Based on the predicted value, the temperature of the exhaust purification catalyst at the time when the exhaust gas is discharged and the accumulated amount of the outflow fuel component during the idling period can be estimated.

  Therefore, in the above case, the temperature raising unit controls the ignition timing, the intake air amount, and the fuel injection amount during the idling period based on the length of the idling period predicted by the idling period predicting device.

This makes it possible to more suitably control the temperature of the exhaust purification catalyst at the end of the idling period and the integrated amount of the outflow fuel component during the idling period.

  Even in the above case, the temperature raising means may minimize the accumulated amount of the outflow fuel component during the idling period within a range where the temperature of the exhaust purification catalyst at the end of the idling period is equal to or higher than the predetermined activation temperature. In addition, the ignition timing, intake air amount, and fuel injection amount during the idling period may be controlled based on the length of the idling period predicted by the idling period prediction device.

  As a result, both the accumulated amount of the spilled fuel component during the idling period and the amount of the spilled fuel component immediately after the end of the idling period can be reduced as much as possible.

  According to the present invention, when the internal combustion engine is started, the length of the idling period immediately after that can be predicted.

  Hereinafter, specific embodiments of an idling period prediction apparatus and a control system for an internal combustion engine according to the present invention will be described with reference to the drawings.

<Example 1>
<Schematic configuration of internal combustion engine and intake / exhaust system thereof>
FIG. 1 is a diagram showing a schematic configuration of an internal combustion engine and its intake / exhaust system according to the present embodiment. The internal combustion engine 1 is a gasoline engine for driving a vehicle having four cylinders 2.

  A piston 3 is slidably provided in the cylinder 2. An intake port 4 and an exhaust port 5 are connected to the combustion chamber in the upper part of the cylinder 2. The openings of the intake port 4 and the exhaust port 5 to the combustion chamber are opened and closed by an intake valve 6 and an exhaust valve 7, respectively.

  The internal combustion engine 1 is also provided with a spark plug 10 that ignites the air-fuel mixture in the combustion chamber in the cylinder 2 and a fuel injection valve 11 that injects fuel into the intake port 4.

  The intake port 4 and the exhaust port 5 are connected to an intake passage 8 and an exhaust passage 9, respectively. An air flow meter 12 and a throttle valve 13 are provided in the intake passage 8. In the present embodiment, the intake air amount of the internal combustion engine 1 is controlled by the throttle valve 13.

  A three-way catalyst 14 is provided in the exhaust passage 14. In this embodiment, the three-way catalyst 14 corresponds to the exhaust purification catalyst according to the present invention. The exhaust purification catalyst according to the present invention is not limited to the three-way catalyst 14, and any catalyst having an oxidation function may be used. Therefore, instead of the three-way catalyst 14, a catalyst such as an oxidation catalyst or a storage reduction type NOx catalyst may be provided.

  Further, the internal combustion engine 1 is provided with a water temperature sensor 15 that detects the temperature of the cooling water flowing in the water jacket formed in the internal combustion engine 1. In this embodiment, the detected value of the water temperature sensor 15 is used as the engine temperature of the internal combustion engine 1. That is, the water temperature sensor 15 corresponds to the engine temperature acquisition means according to the present invention.

The internal combustion engine 1 configured as described above is provided with an electronic control unit (ECU) 20. The ECU 20 is electrically connected to an air flow meter 12, a water temperature sensor 15, a crank position sensor 16, an accelerator opening sensor 17, and an ignition switch 18. These output signals are input to the ECU 20.

  The crank position sensor 16 is a sensor that detects the crank angle of the internal combustion engine 1. The accelerator opening sensor 17 is a sensor that detects the accelerator opening of a vehicle on which the internal combustion engine 1 is mounted.

  Further, the ECU 20 is electrically connected with a spark plug 10, a fuel injection valve 11, and a throttle valve 13. These are controlled by the ECU 20.

<Control during idling period>
In this embodiment, the control during the idling period in which the operating state of the internal combustion engine 1 is in the idling state will be described. In the following description, the “idling period” refers to an “idling period immediately after starting the internal combustion engine 1”.

  In the internal combustion engine 1 according to this embodiment, the engine speed (idle speed) is controlled to a predetermined target idle speed during the idling period. At this time, when it is not necessary to raise the temperature of the three-way catalyst 14 (that is, when the three-way catalyst 14 is sufficiently activated), the ignition timing and the intake air amount of the internal combustion engine 1 are respectively determined in advance. The basic ignition timing and the basic air amount are controlled. That is, the basic ignition timing and the basic air amount are determined as values at which the idle speed becomes the target idle speed when the ignition timing and the intake air amount of the internal combustion engine are controlled to these values.

  Here, when the internal combustion engine 1 is cold-started, it is necessary to activate the three-way catalyst 14 earlier. Therefore, in this embodiment, when the internal combustion engine 1 is cold-started, the temperature increase control is executed to increase the temperature of the three-way catalyst 14 during the idling period immediately after that. The temperature increase control according to this embodiment is realized by retarding the ignition timing of the internal combustion engine from the basic ignition timing. By retarding the ignition timing, the exhaust temperature can be raised. As a result, the temperature of the three-way catalyst 14 can be raised more quickly.

  Further, if the ignition timing is retarded during the idling period, there is a possibility that the idling speed will be reduced. Therefore, in the present embodiment, when the temperature increase control is executed during the idling period, intake air amount increase control for increasing the intake air amount from the basic air amount is executed. In this intake air amount increase control, the intake air amount is controlled so that the idle speed when the ignition timing is retarded becomes the target idle speed. The intake air amount increase control according to this embodiment is realized by increasing the opening of the throttle valve 13.

  As described above, in the present embodiment, when the internal combustion engine 1 is cold-started, the temperature increase control and the intake air amount increase control are executed during the idling period, so that the idle speed is set to the target idle speed. While controlling, the temperature of the three-way catalyst 14 can be increased more quickly.

  When the temperature increase control is executed during the idling period, the temperature increase of the three-way catalyst 14 can be further promoted by increasing the retard amount of the ignition timing. However, if the ignition timing is retarded excessively, the unburned fuel component in the exhaust gas increases, so that the unburned fuel component that flows out downstream from the three-way catalyst 14 during the temperature rise of the three-way catalyst 14 (hereinafter referred to as the unburned fuel component) The amount of the spilled fuel component) may increase. As a result, there is a possibility that the integrated amount of the outflow fuel component during the idling period increases excessively. On the other hand, if the temperature of the three-way catalyst 14 is not sufficiently raised during the idling period, it becomes difficult to sufficiently suppress the amount of the outflow fuel component immediately after the end of the idling period.

Therefore, in this embodiment, when the internal combustion engine 1 is cold started, the length of the idling period immediately after that is predicted. Then, in order to reduce as much as possible both the integrated amount of the spilled fuel component during the idling period and the amount of the spilled fuel component immediately after the end of the idling period, the ignition during the idling period is based on the predicted value of the length of the idling period. Control the timing.

<Prediction method of idling period length>
Here, a method of predicting the length of the idling period according to the present embodiment will be described with reference to FIG. The length of the idling period is one of the driving patterns of the driver of the vehicle on which the internal combustion engine 1 is mounted. Further, the length of the idling period tends to change according to the engine temperature when the internal combustion engine 1 is started. That is, normally, when the engine temperature at the start of the internal combustion engine 1 is low, the idling period tends to be longer than when the engine temperature at the start of the internal combustion engine 1 is high due to warming up of the internal combustion engine 1. is there. From these things, the length of an idling period can be estimated based on the history.

  Therefore, in this embodiment, the ECU 20 measures the length of the idling period every time the internal combustion engine 1 is started. In this embodiment, the accelerator opening detected by the accelerator opening sensor 17 from the time when the ignition switch 18 is turned ON and the engine speed of the internal combustion engine 1 becomes equal to or higher than a predetermined engine start speed (for example, 400 rpm). The length of the period until becomes larger than zero is measured as the length of the idling period. Here, the engine starting rotational speed is a threshold value at which it can be determined that fuel injection from the fuel injection valve 11 and ignition by the spark plug 10 have started in the internal combustion engine 1. As shown in FIG. 2, the ECU 20 stores the measured value in association with the temperature of the cooling water detected by the water temperature sensor 15 at the time of measurement (that is, at the time of engine start).

  From the time when the ignition switch 18 is turned on and the engine speed of the internal combustion engine 1 becomes equal to or higher than the predetermined engine start speed, the time when the engine speed of the internal combustion engine 1 becomes equal to or higher than the predetermined idle end speed. The length of the period may be measured as the length of the idling period. Here, the idle end rotational speed is a value higher than the target idle rotational speed. Further, a period from the time when the ignition switch 18 is turned ON and the engine speed of the internal combustion engine 1 becomes equal to or higher than a predetermined engine start speed until the time when the engine load of the internal combustion engine 1 becomes equal to or higher than a predetermined idle end load. May be measured as the length of the idling period. Here, the idle end load is a value higher than the engine load when the internal combustion engine 1 is operated at the target idle speed.

  In the present embodiment, the ECU 20 that measures the length of the idling period corresponds to the measuring means according to the present invention. Moreover, ECU20 which memorize | stores the length of an idling period is equivalent to the memory | storage means which concerns on this invention.

  In FIG. 2, the upper vertical axis represents the idling period length Δti, and the lower vertical axis represents the cooling water temperature Tw. The first predetermined water temperature Tw1 is a threshold value that is determined to be a cold start when the cooling water temperature Tw is equal to or lower than the first predetermined water temperature Tw1 when the internal combustion engine 1 is started (for example, Tw1 = 40 ° C.). . In FIG. 2, the horizontal axis represents the time-series engine start frequency (“n” for the nth engine start).

  When the internal combustion engine 1 is cold-started, the latest predetermined number of data is selected from the length Δti of the idling period when the internal combustion engine 1 has been cold-started in the past. Then, an average value of the selected predetermined number of data is calculated, and the average value is set as a predicted value of the length Δtith of the present idling period.

  The predetermined number of times is the number of times that it can be determined that the idling period length Δtit can be predicted with sufficient accuracy, and is determined in advance based on experiments or the like.

  As an example, the case where the current cold start is the (n + 1) th engine start and the predetermined number of times is 5 will be described. In this case, the engine idling before the nth time and the cooling water temperature Tw at the time of engine starting is equal to or less than the first idling period length Δti when the cooling water temperature Tw is equal to or lower than the first predetermined water temperature Tw1. Data for 5 times (data enclosed in an ellipse in the upper part of FIG. 2) is selected. Then, the average value of the selected data for five times is set as the predicted value of the length Δtith of the current idling period.

  According to the method for predicting the length of the idling period as described above, the length of the idling period is predicted based on the history while considering the coolant temperature at the start of the internal combustion engine 1. Therefore, when the internal combustion engine 1 is cold started, the length of the idling period immediately after that can be predicted with higher accuracy.

<Ignition timing and throttle valve opening during idling period>
When the temperature increase control is executed during the idling period after the cold start of the internal combustion engine 1, the three-way catalyst 14 at the end of the idling period is determined according to the retard amount of the ignition timing and the length of the idling period. The accumulated amount of the spilled fuel component during the temperature and idling period changes. For example, when the retard amount of the ignition timing during the idling period is constant, the longer the idling period, the higher the temperature of the three-way catalyst 14 at the end of the idling period, and the outflow fuel component during the idling period The accumulated amount of increases. Further, when the length of the idling period is constant, the temperature of the three-way catalyst 14 at the end of the idling period becomes higher as the retard amount of the ignition timing during the idling period is larger (that is, the ignition timing is later). Therefore, the accumulated amount of the outflow fuel component during the idling period increases.

  Therefore, in this embodiment, the accumulated amount of the outflow fuel component during the idling period is minimized within a range where the temperature of the three-way catalyst 14 at the end of the idling period is equal to or higher than a predetermined activation temperature. The relationship between the ignition timing during the idling period and the length of the idling period is obtained in advance based on experiments and the like. Then, these relationships are stored in the ECU 20 as a map as shown in FIG.

  Here, the predetermined activation temperature is a value by which it can be determined that the amount of the outflow fuel component falls within the allowable range if the temperature of the three-way catalyst 14 is equal to or higher than the predetermined activation temperature. This predetermined activation temperature is predetermined based on experiments and the like.

  In FIG. 3, the vertical axis represents the ignition timing SA during the idling period, and the horizontal axis represents the length Δti of the idling period. The curve L1 represents the case where the cooling water temperature at the time of engine start is the first predetermined water temperature Tw1, the curve L2 represents the case where the cooling water temperature at the time of engine start is the second predetermined water temperature Tw2, and the curve L3 represents the engine L3. This represents the case where the cooling water temperature at the start is the third predetermined water temperature Tw3 (Tw1> Tw2> Tw3). As described above, the map shown in FIG. 3 stores the relationship between the ignition timing during the idling period and the length of the idling period according to the coolant temperature at the time of starting the engine.

  Then, when the internal combustion engine 1 is cold started, the ECU 20 predicts the length of the idling period immediately after that by the above method. Then, the ECU 20 determines the ignition timing during the present idling period by substituting the predicted value into the map shown in FIG. Further, the ECU 20 retards the ignition timing during the idling period from the basic ignition timing, and controls it to the value determined in this way.

Thereby, the temperature of the three-way catalyst 14 at the end of the idling period can be controlled to be equal to or higher than a predetermined activation temperature while suppressing the accumulated amount of the outflow fuel component during the idling period as much as possible. Therefore, when the internal combustion engine 1 is cold-started, it is possible to reduce as much as possible both the integrated amount of the outflow fuel component during the idling period and the amount of the outflow fuel component immediately after the end of the idling period.

  In the present embodiment, even when the ignition timing is controlled to the value determined as described above during the idling period, the idle rotation speed is set to the target idle rotation speed by executing the intake air amount increase control. The amount of intake air is increased until Thereby, it is suppressed that idling rotation speed falls.

<Control routine during idling period>
Hereinafter, the control routine during the idling period according to the present embodiment will be described based on the flowchart shown in FIG. This routine is stored in advance in the ECU 20, and is repeatedly executed at predetermined intervals when the ECU 20 is ON.

  In this routine, first, in S101, the ECU 20 determines whether or not the ignition switch 18 is turned ON and the engine speed Ne of the internal combustion engine 1 is equal to or higher than a predetermined engine start speed Nes. If an affirmative determination is made in S101, the ECU 20 determines that the internal combustion engine 1 has been started, and proceeds to S102. On the other hand, if a negative determination is made in S101, the ECU 20 ends the execution of this routine.

  In S102, the ECU 20 determines whether or not the cooling water temperature Tw detected by the water temperature sensor 15 is equal to or lower than the first predetermined water temperature Tw1. If an affirmative determination is made in S102, the ECU 20 determines that the internal combustion engine 1 has been cold-started, and proceeds to S103. On the other hand, if a negative determination is made in S102, the ECU 20 proceeds to S110.

  When the ECU 20 proceeds to S110, it is not necessary to execute the temperature increase control and the intake air amount increase control during the idling period. Therefore, in S110, the ECU 20 controls the ignition timing SA of the internal combustion engine 1 to the basic ignition timing SAbase. Further, the ECU 20 controls the opening degree TA of the throttle valve 13 to the basic opening degree TAbase. Here, the basic opening degree TAbase is set as an opening degree at which the intake air amount of the internal combustion engine 1 becomes the basic air amount. The ECU 20 proceeds to S108 after S110.

  On the other hand, the ECU 20 that has proceeded to S103 predicts the current idling period length Δtit by the above-described prediction method. In the present embodiment, the ECU 20 that executes S103 corresponds to the prediction means according to the present invention.

  Next, the ECU 20 proceeds to S104, and derives the ignition timing SAth during the current idling period by substituting the length Δtith of the current idling period predicted in S103 into the map shown in FIG.

  Next, the ECU 20 proceeds to S105 and controls the ignition timing SA of the internal combustion engine 1 to the ignition timing SAth. As a result, the ignition timing SA is retarded from the basic ignition timing, and the temperature raising control is executed. In this embodiment, the ECU 20 that executes S105 corresponds to the temperature raising means according to the present invention.

  Next, the ECU 20 proceeds to S106 and increases the opening degree TA of the throttle valve 13 beyond the basic opening degree TAbase. As a result, intake air amount increase control is executed.

Next, the ECU 20 proceeds to S107 and determines whether or not the engine speed of the internal combustion engine 1, that is, the idle speed Nei has reached the target idle speed Neit. In S107
If an affirmative determination is made, the ECU 20 proceeds to S108, and if a negative determination is made, the ECU 20 returns to S106.

  In S108, the ECU 20 determines whether or not the accelerator opening degree Racc detected by the accelerator opening degree sensor 17 is greater than zero. If an affirmative determination is made in S108, the ECU 20 proceeds to S109, and if a negative determination is made, the ECU 20 repeats S108.

  In S109, the ECU 20 determines the actual length Δtisth ′ of the present idling period (that is, the length of the period from when the ignition switch 18 is turned on until the accelerator opening Racc becomes greater than zero). It is stored in correspondence with the cooling water temperature Tw at the time. Thereafter, the ECU 20 once terminates execution of this routine.

In the method of predicting the length of the idling period according to the present embodiment, the region where the cooling water temperature Tw shown in the lower part of FIG. 2 is equal to or lower than the first predetermined water temperature Tw1 may be further divided into a plurality of regions (for example, The region is divided into a region of Tw1 ≧ Tw> Tw2, a region of Tw2 ≧ Tw> Tw3, and a region of Tw3 ≧ Tw). In this case, when predicting the length of the idling period at the time of cold start of the internal combustion engine 1, the length of the idling period for the past predetermined number of times in the region to which the cooling water temperature belongs is selected, and these data The average value is taken as the predicted value.

  According to this, it becomes possible to predict the length of the idling period with higher accuracy than the above.

  In the above description, the average value of the selected idling periods for the predetermined number of times in the past is used as the predicted value of the length of the current idling period, but a representative value other than the average value of the selected data is used as the predicted value. It may be used as

  Further, in the intake air amount increase control during the idling period, after the ignition timing is retarded from the basic ignition timing, the opening degree of the throttle valve 13 is increased until the idle speed reaches the target idle speed. . However, the opening degree of the throttle valve 13 at which the idle rotation speed becomes the target idle rotation speed may be obtained in advance by experiments or the like according to the ignition timing, and the relationship between them may be stored in the ECU 20 as a map. By controlling the opening degree of the throttle valve 13 to a value derived from such a map when the intake air amount increase control is executed, the idle speed can be controlled to the target idle speed more quickly.

  In this embodiment, the air-fuel ratio of the exhaust during the idling period may be controlled to a predetermined target air-fuel ratio. In this case, when the temperature raising control is not executed during the idling period, the fuel injection time by the fuel injection valve 11 is controlled to the basic injection time. Here, the fuel injection time is the time required for one fuel injection by the fuel injection valve 11. That is, the fuel injection time can be regarded as the fuel injection amount per fuel injection by the fuel injection valve 11. The basic injection time is determined as a value at which the air-fuel ratio of the exhaust becomes the target air-fuel ratio when the intake air amount of the internal combustion engine is the basic air amount.

  On the other hand, when the temperature increase control is executed during the idling period, the fuel injection time is made longer than the basic injection time in accordance with the increase in the intake air amount (that is, the fuel injection amount per fuel injection is increased). ) As a result, even when the temperature raising control is executed during the idling period, the air-fuel ratio of the exhaust can be controlled to the target air-fuel ratio.

<Example 2>
The schematic configuration of the internal combustion engine and its intake / exhaust system according to this embodiment is the same as that of the first embodiment. Also in the present embodiment, when the internal combustion engine 1 is cold-started, similarly to the first embodiment, the temperature increase control and the intake air amount increase control are executed during the idling period.

<Ignition timing and intake air amount during idling period>
Hereinafter, a method for setting the ignition timing, the opening degree of the throttle valve, and the fuel injection time during the idling period according to the present embodiment will be described.

  In this embodiment, during the idling period, the temperature of the three-way catalyst 14 and the amount of the outflow fuel component according to the elapsed time from the starting time of the internal combustion engine 1 (hereinafter also referred to as elapsed time after starting) are determined. The following equations (1) and (2) for calculation are stored in the ECU 20. These equations (1) and (2) can be obtained in advance based on experiments and the like. Here, a case where the temperature of the three-way catalyst 14 and the amount of the outflow fuel component are calculated every 0.1 sec during the idling period will be described as an example.

Tcat (t) = aTcat (t−0.1) + bTcat (t−0.2) + f (TA (t−td), SA (t−td), INJ (t−td)) (1) )
Tcat (t): temperature of the three-way catalyst 14 at the elapsed time t after startup (° C.)
TA (t): Opening degree (deg) of throttle valve 13 at elapsed time t after starting
SA (t): ignition timing at the elapsed time t after start (degBTDC)
INJ (t): fuel injection time (μsec) at elapsed time t after starting
a, b: constant, f: function, td: response delay time

  In the above formula (1), Tcat (t−0.1) is the temperature of the three-way catalyst 14 0.1 sec before the elapsed time t after starting. Tcat (t−0.2) is the temperature of the three-way catalyst 14 0.2 seconds before the elapsed time t after startup. Further, there is a response delay until the temperature of the three-way catalyst 14 changes according to the changes after the opening of the throttle valve 13, the ignition timing, and the fuel injection time change. TA (t-td), SA (t-td), and INJ (t-td) are the opening, ignition timing, and fuel injection time of the throttle valve 13 before the response delay time td from the post-start elapsed time t. It is.

HC (t) = cHC (t−0.1) + dHC (t−0.2) + g (TA (t−td), SA (t−td), INJ (t−td), Tcat (t−td) ) ... Formula (2)
HC (t): Amount of fuel flowing out at elapsed time t after start (g / sec)
c, d: constant, g: function, td: response delay time

  In the above formula (2), HC (t−0.1) is the amount of the outflow fuel component 0.1 sec before the elapsed time t after starting. HC (t−0.2) is the amount of the outflow fuel component 0.2 sec before the elapsed time t after starting. In addition, there is a response delay from when the opening degree of the throttle valve 13, the ignition timing, the fuel injection time, and the temperature of the three-way catalyst 14 each change until the amount of the outflow fuel component changes accordingly. TA (t-td), SA (t-td), INJ (t-td), and Tcat (t-td) are the opening of the throttle valve 13 before the response delay time td from the start-and-after movement elapsed time t. Degree, ignition timing, fuel injection time, and temperature of the three-way catalyst 14.

  Also in the present embodiment, when the internal combustion engine 1 is cold started, the ECU 20 predicts the idling period length Δtit immediately after that by the same method as in the first embodiment.

By substituting the estimated value Δtith of the length of the idling period into t in the equation (1), the temperature of the three-way catalyst 14 at the time when the present idling period ends can be calculated. Further, by integrating the value obtained by substituting the estimated value Δtith of the idling period length from 0 to t in the equation (2), the integrated amount of the spilled fuel component during the idling period can be calculated.

  Therefore, in this embodiment, the ECU 20 satisfies the following formula (3), and the throttle during the idling period in which the accumulated amount J of the outflow fuel component during the idling period calculated by the following formula (4) is minimized. The opening degree TA (t) of the valve 13, the ignition timing SA (t), and the fuel injection time INJ (t) are calculated in time series.

Tcat (Δtit) ≧ Tcatact (3)
Tcat (Δtit): temperature of the three-way catalyst 14 at the end of the current idling period Tcatact: predetermined activation temperature

Ｊ：アイドリング期間中の流出燃料成分の積算量

J: Cumulative amount of spilled fuel component during idling period

  According to the above, optimum control values for the opening degree of the throttle valve 13, the ignition timing, and the fuel injection time during the idling period as shown in FIG. 5 can be obtained when the internal combustion engine 1 is cold started. I can do it.

  In this embodiment, the ECU 20 determines the opening degree, the ignition timing, and the fuel injection time of the throttle valve 13 during the idling period in a time series as shown in FIG. 5, TA (t), SA (t). And INJ (t). In this embodiment, the ECU 20 that controls the opening degree of the throttle valve 13, the ignition timing, and the fuel injection time during the idling period corresponds to the temperature raising means according to the present invention.

  Thereby, the temperature of the three-way catalyst 14 at the end of the idling period can be controlled to be equal to or higher than a predetermined activation temperature while suppressing the accumulated amount of the outflow fuel component during the idling period as much as possible. Therefore, according to this embodiment, when the internal combustion engine 1 is cold-started, both the accumulated amount of the spilled fuel component during the idling period and the amount of the spilled fuel component immediately after the end of the idling period are minimized. I can do it.

  In Examples 1 and 2, when the internal combustion engine 1 was cold started, the length of the idling period immediately after that was predicted based on the history. However, the length of the idling period at the cold start may be predicted more simply by the following method.

  That is, when the internal combustion engine 1 is cold-started, the cooling water temperature of the internal combustion engine 1 is lower than the fourth predetermined water temperature and the blowout port of the vehicle interior blower is ON in the front window state. It is predicted that the idling period immediately after that is a predetermined time longer than that in the normal time.

Here, the fourth predetermined water temperature is a threshold (for example, −2 ° C.) from which it can be determined that there is a high possibility that the front window is frosted. That is, when the cooling water temperature of the internal combustion engine 1 is equal to or lower than the fourth predetermined water temperature and the blowout port of the vehicle interior blower is ON in the front window state, the front window is defrosted during the idling period. It can be judged that Therefore, in such a case, the length of the idling period is predicted to be longer than in the normal case.

  The embodiments described above can be combined as much as possible.

The figure which shows schematic structure of the internal combustion engine which concerns on the Example of this invention, and its intake / exhaust system. The figure for demonstrating the prediction method of the length of the idling period which concerns on the Example of this invention. The map which shows the relationship between the ignition timing in the idling period and the length of an idling period based on Example 1 of this invention. The flowchart which shows the control routine in the idling period which concerns on Example 1 of this invention. The figure which shows the transition of the throttle valve opening degree, the ignition timing and the control value of the fuel injection time, the idle speed, the temperature of the three-way catalyst, and the amount of the outflow fuel component during the idling period according to the second embodiment of the present invention. .

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Internal combustion engine 2 ... Cylinder 8 ... Intake passage 9 ... Exhaust passage 10 ... Spark plug 11 ... Fuel injection valve 12 ... Air flow meter 13 ... Throttle valve 14 ... Three-way catalyst 15. ・ Water temperature sensor 16 ・ ・ Crank position sensor 17 ・ Accelerator opening sensor 18 ・ ・ Ignition switch 20 ・ ・ ECU

Claims (7)

Measuring means for measuring the length of an idling period, which is a period in which the operating state of the internal combustion engine is in an idling state immediately after starting the internal combustion engine;
Storage means for storing the length of the idling period measured by the measurement means;
An idling period prediction device comprising: a predicting unit that predicts a length of a current idling period based on a plurality of past idling period lengths stored in the storage unit when the internal combustion engine is started ; ,
When the internal combustion engine is cold-started, the temperature of the exhaust purification catalyst provided in the exhaust passage of the internal combustion engine is increased by retarding the ignition timing of the internal combustion engine from the basic ignition timing during the idling period. An internal combustion engine control system comprising:
The control system for an internal combustion engine, wherein the temperature raising means controls the ignition timing during the idling period based on the length of the idling period predicted by the idling period predicting device. The idling period predicting device is
Further comprising a engine temperature obtaining means for obtaining the engine temperature at the start of the internal combustion engine,
The storage means stores the length of the idling period measured by the measurement means in association with the engine temperature acquired by the engine temperature acquisition means,
When the internal combustion engine is started, the engine temperature at the start of the internal combustion engine corresponding to the past idling period stored in the storage unit is acquired by the engine temperature acquisition unit this time. 2. The control of an internal combustion engine according to claim 1, wherein a part within a predetermined range including the engine temperature is selected a plurality of times, and the length of the current idling period is predicted based on the lengths. System . In the idling period prediction device,
3. The internal combustion engine according to claim 1, wherein the predicting unit sets a representative value of the length of a past idling period for a predetermined number of times stored in the storage unit as a predicted value of the length of the idling period. Engine control system . The temperature raising means is an unburned fuel component that flows out downstream of the exhaust purification catalyst during the idling period within a range where the temperature of the exhaust purification catalyst at the end of the idling period is equal to or higher than a predetermined activation temperature. The control system for an internal combustion engine according to any one of claims 1 to 3, wherein an ignition timing during an idling period is controlled so that an integrated amount of the engine is minimized. Claim 1 the ignition timing during idling period by said Atsushi Nobori means when the result is retarded from the basic ignition timing, characterized in that the increase than the basic air quantity of intake air amount of the internal combustion engine during idling periods 5. A control system for an internal combustion engine according to any one of claims 1 to 4 . Measuring means for measuring the length of an idling period, which is a period in which the operating state of the internal combustion engine is in an idling state immediately after starting the internal combustion engine;
Storage means for storing the length of the idling period measured by the measurement means;
An idling period prediction device comprising: a predicting unit that predicts a length of a current idling period based on a plurality of past idling period lengths stored in the storage unit when the internal combustion engine is started ; ,
When the internal combustion engine is cold started, an exhaust purification catalyst provided in the exhaust passage of the internal combustion engine is controlled by controlling the ignition timing, intake air amount and fuel injection amount of the internal combustion engine during the idling period. In a control system for an internal combustion engine comprising a temperature raising means for raising the temperature,
The temperature raising means controls the ignition timing, intake air amount, and fuel injection amount during the idling period based on the length of the idling period predicted by the idling period predicting device. system. The temperature raising means is an unburned fuel component that flows out downstream of the exhaust purification catalyst during the idling period within a range where the temperature of the exhaust purification catalyst at the end of the idling period is equal to or higher than a predetermined activation temperature. The ignition timing, the intake air amount, and the fuel injection amount during the idling period are controlled based on the length of the idling period predicted by the idling period predicting device so that the integrated amount of the engine is minimized. The control system for an internal combustion engine according to claim 6 .

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