JP3491019B2 - Idle rotation learning control system for electronically controlled throttle internal combustion engine - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an idle speed learning control system for an electronically controlled throttle internal combustion engine, and more specifically,
The present invention relates to an internal combustion engine equipped with an electronically controlled throttle system for electronically controlling the opening of a throttle valve, which controls the idle speed by controlling the opening of the throttle valve.

[0002]

2. Description of the Related Art Conventionally, while a throttle valve is configured to be opened and closed by an actuator such as a motor, a target air amount is set based on an accelerator operation amount,
There is known an electronically controlled throttle system configured to electronically control the opening of a throttle valve so that the target air amount can be obtained.

Further, during idle operation of the engine, the intake air amount of the engine is feedback-controlled so that the engine speed approaches the target idle speed, while the feedback correction is performed when a predetermined learning condition is satisfied. A configuration is known in which the amount of air is learned as the amount of change in the opening area that decreases over time due to dirt and clogging of the intake system, and the amount of intake air is corrected based on the learned value.

[0004]

By the way, in an engine equipped with the electronically controlled throttle system for setting the target air amount and controlling the throttle valve opening as described above, it is necessary to control the opening of the throttle valve. In some cases, the target idle speed is obtained, but in such a configuration, the learning value is generally learned as the air amount (liter / min).

However, the conditions for performing the learning (for example, idle, complete heating, electric load OFF, neutral)
In the state where the electric load is applied to the air intake valve, even if the learning value as the air flow rate is reflected, since the suction negative pressure is different from that at the learning time, the air corresponding to the decreasing change amount of the opening area is reflected. There was a problem that the target idle rotation speed could not be stably obtained without correcting the amount.

That is, the learning value indicates how much the air amount decreases and changes under the learning conditions due to the decrease and change in the opening area due to dirt and clogging. If the suction negative pressure condition is different, the opening value is changed. Since the change in the air amount due to the change in the decrease in the area is different, even if the learned value is reflected when the suction negative pressure is different from the learning condition, the correction was made to match the decrease in the air amount due to the decrease in the opening area. It doesn't.

The present invention has been made in view of the above problems, and in an internal combustion engine having an electronically controlled throttle system and configured to obtain a target idle rotation speed by electronically controlling the opening of a throttle valve, an intake valve different from that during learning is used. An object of the present invention is to provide an idle rotation learning control device capable of correcting an air amount corresponding to dirt and clogging of an intake system by a learned value even when pressure is reduced.

[0008]

Therefore, the idle rotation learning control device according to the invention as set forth in claim 1 sets a target air amount according to the operating condition of the engine, and sets the target air amount to the target opening of the throttle valve. An electronically controlled throttle internal combustion engine having an electronically controlled throttle system which is converted into an area and which opens and closes a throttle valve by an actuator so as to have the target opening area is configured as shown in FIG.

In FIG. 1, the idle rotation feedback control means feedback-controls the target air amount so that the engine rotation speed approaches the target idle rotation speed during idle operation of the engine. The idle rotation learning means, when a predetermined learning condition is satisfied, the correction air amount by the idle rotation feedback control means,
The throttle valve is converted into the opening area of the throttle valve based on the correlation between the air amount at the suction negative pressure and the opening area under the predetermined learning condition, and the opening area is learned as an idle rotation learning value.

The learning correction means corrects and sets the target opening area based on the idle rotation learning value as the opening area learned by the idle rotation learning means. According to such a configuration, the target air amount is feedback-corrected to obtain the target idle rotation speed, and the air amount corrected by the feedback correction is used for the intake system when the predetermined learning condition is satisfied. Learned as the amount of change in the decrease of the opening area due to
Of air volume and opening area at negative suction pressure under learning conditions
Based on the correlation, it is converted into an opening area (cm ² ) and a learning value as the opening area is set. Then, the target opening area obtained by converting the target air amount is corrected and set by the learning value learned as the opening area.

According to a second aspect of the present invention, the combustion system of the internal combustion engine is switched between stratified combustion by injection in the compression stroke and homogeneous combustion by injection in the intake stroke, and the idle rotation learning is performed. The means is configured to prohibit the stratified combustion and perform learning in the homogeneous combustion state when a predetermined learning condition is satisfied. According to this configuration, when learning is to be performed, if stratified charge combustion (combustion with an ultra-lean air-fuel ratio) is being performed, learning is performed after switching to homogeneous combustion (combustion with an air-fuel ratio richer than during stratified charge combustion). As a result, the learning is performed under the condition that the intake air amount of the engine is small and the influence of dirt and clogging is more likely to appear.

According to a third aspect of the present invention, the idle rotation learning means performs the learning once every time the ignition switch is turned on. According to this configuration,
If the learning is performed even once after the ignition switch is turned on, thereafter, the learning with prohibition of the stratified combustion is not performed even if the learning condition is satisfied.

[0013]

According to the first aspect of the present invention, the correction amount of the target air amount when the target idle speed is obtained by feedback-correcting the target air amount of the electronically controlled throttle system is used as the intake system dirt and clogging. When learning as a minute ,
Phase of Air Volume and Opening Area under Negative Suction Pressure under Training Condition
Since the opening area of the throttle valve is converted based on the relationship, even if the condition of the suction negative pressure changes, the air amount can be corrected corresponding to the decrease in the opening area due to the dirt and clogging. The effect is that you can do it.

According to the second aspect of the present invention, the learning of the reduction change due to the dirt and clogging of the opening area of the intake system is performed by switching from the stratified combustion state to the homogeneous combustion state, so the dirt and clogging. There is an effect that the learning can be performed in a state in which the decrease amount of the air amount due to the ratio of the total amount of air is high, and thus the learning can be performed with high accuracy.

According to the third aspect of the present invention, there is an effect that the learning by switching from the stratified combustion to the homogeneous combustion is performed more frequently than necessary, and it is possible to prevent the fuel consumption performance and the exhaust property from being deteriorated.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below. FIG. 2 is a system configuration diagram of an internal combustion engine according to the embodiment. The internal combustion engine 1 shown in FIG. 2 includes a fuel injection valve 2 that directly injects fuel into each cylinder, and also has each cylinder. It is a direct-injection gasoline engine (a direct-injection spark ignition engine) equipped with a spark plug 4 at the front.

The fuel injection valve 2 is controlled for each cylinder according to an injection pulse signal from a control unit 3 having a built-in microcomputer.
Further, each ignition plug 4 is provided with an ignition coil 5, and the power transmission unit 6 turns on / off the power supply to the primary side of each ignition coil 5 in response to an ignition signal from the control unit 3. The ignition timing is controlled for each cylinder.

On the other hand, an electronically controlled throttle system is provided which opens and closes a throttle valve 8 for measuring the intake air amount of the engine by a motor 13 controlled by the control unit 3. Detection signals are input to the control unit 3 from various sensors for fuel injection control, ignition timing control, throttle opening control, and the like.

As the various sensors, an air flow meter 7 for detecting the intake air flow rate, a throttle sensor 9 for detecting the opening of the throttle valve 8, a crank angle sensor 10 for detecting the crank angle, and a water temperature sensor for detecting the cooling water temperature. 1
1. Oxygen sensor 12 that detects the average air-fuel ratio of the combustion mixture based on the oxygen concentration in the exhaust gas 12. Vehicle speed sensor that detects the vehicle speed
14, neutral switch 15 for detecting the neutral state of the transmission, electric load switch 16, accelerator position sensor
17 etc. are provided.

Here, the control unit 3 is
A plurality of target equivalence ratio maps in which a target equivalence ratio (target air-fuel ratio) and a combustion mode are preset according to the target output torque and engine speed are provided, and the plurality of target equivalence ratio maps are used for the water temperature, the time after starting, and the vehicle speed. , The target equivalent ratio and the request for the combustion mode are discriminated, and the fuel injection amount and the injection timing by the fuel injection valve 2 are controlled.

The combustion mode is a homogeneous combustion mode in which fuel is injected in the intake stroke to perform homogeneous combustion, and a fuel is injected in the compression stroke to form a rich air-fuel mixture in the vicinity of the spark plug 4 to form a stratified lean mixture. A stratified combustion mode for performing combustion is set, and in the homogeneous combustion mode, the target equivalence ratio is controlled to lean, stoichiometric (theoretical air-fuel ratio), or rich according to the operating region,
In the stratified charge combustion mode, leaner control is performed than in homogeneous lean combustion.

The control unit 3 electronically controls the opening of the throttle valve 8 as shown in FIG. First, a target air amount (liter / min) is calculated based on the accelerator opening, the engine rotation speed Ne, the target equivalent ratio, etc. (S1). The calculation of the target air amount includes the calculation of the reference target air amount and the setting of the final target air amount by correcting the reference target air amount.

The target air amount is converted into the throttle opening area (S2), and the opening area is converted into the target opening degree of the throttle valve 8 (S3). Then, the motor 13 is feedback-controlled so that the actual opening detected by the throttle sensor 9 matches the target opening.
Incidentally, the addition correction of the opening area learning value in FIG. 3 will be described later.

Further, the control unit 3 sets the feedback correction air amount QFBI (liter / min) by integral control so that the engine rotation speed approaches the target idle rotation speed during idle operation, and the feedback correction air amount QFBI is set. The target air amount (reference target air amount) is corrected. The function of the control unit 3 corresponds to idle rotation feedback control means.

Further, the amount of intake air obtained with respect to the opening is reduced due to a decrease in the opening area with respect to the opening due to the dirt of the throttle valve 8 and the like. The situation will be described with reference to FIG. In FIG. 4, first, it is determined whether the learning condition is satisfied (S11). The learning condition is that the feedback control of the idle rotation is being performed, the temperature is in a completely warmed / neutral state, and no load such as an electric load and an air conditioner load is applied.

Even if it is determined that the learning condition is satisfied,
Next, when it is determined by the learning end flag that learning has already been completed, learning is not performed (S12). The learning end flag is set when learning is performed, and is reset by turning the ignition switch ON → OFF. Therefore, the learning end flag is learned during one trip (from ON to OFF of the ignition switch). Is performed once, learning is prohibited even if the learning condition is satisfied.

The decrease in the opening area with time does not change abruptly, and the learning value can be made to sufficiently follow by executing the operation once per trip. On the other hand, for example, when learning is performed every time a learning condition is satisfied, if learning is performed a plurality of times during one trip, the learning is performed by forcibly switching to homogeneous combustion, which will be described later. Will only result in worsening. Therefore, in this embodiment, learning is performed only once during one trip.

When it is determined that the learning conditions are satisfied and the learning is not completed as described above, a homogeneous combustion request is generated (S13), and when the stratified combustion is being performed, the homogeneous combustion is forcibly performed. Switch to. The target equivalence ratio is made rich by the switching of the combustion system, and the intake air amount of the engine corresponding to the target torque (reference target air amount) is reduced and changed. You will be able to learn.

Immediately after switching to the homogeneous combustion, the engine becomes unstable. Therefore, after waiting for a certain delay time, the learning is started (S14). In learning, first, the feedback correction air amount QFBI is sampled at regular intervals (S15), and an average value QFBIAV of the sampled air amount QFBI is calculated (S16).

Then, the air amount learning correction value IS up to that point
CLRC and the average value QFBIAV are weighted averaged, and the weighted average value is updated and stored as a new air amount learning correction value ISCLRC (S17). However, the air amount learning correction value ISCLRC is limited to a predetermined maximum / minimum value (S18).

When the air amount learning correction value ISCLRC is updated, the learning end flag is set (S19),
Release the request for homogeneous combustion and permit stratified combustion (S2
0). The air amount learning correction value ISCLRC (liter / m
in) is the opening area learning value ATASL based on the coefficient for converting the flow rate into the throttle opening area under the learning conditions.
It is converted into N (cm ² ) (S21).

As shown in FIG. 3, the opening area learning value ATASLN is added to the target opening area obtained by converting the target air amount, and the addition-corrected target opening area is converted into the throttle opening. To do so. The air amount learning correction value ISCLRC is a value corresponding to the decrease change in the opening area when the learning condition is satisfied, but when the suction negative pressure is different, the air amount corresponding to the decrease change in the opening area changes. In order to do so, the air amount learning correction value IS
CLRC does not correct the amount of decrease in the opening area. On the other hand, the opening area learning value ATASL
Since N is a value that directly indicates the amount of decrease in the opening area, the opening area is corrected by the opening area learning value ATASLN even when the suction negative pressure is different from that during learning. The correction is made to compensate for the decrease in the air amount due to the decrease change in

[Brief description of drawings]

FIG. 1 is a block diagram showing a basic configuration of the invention according to claim 1.

FIG. 2 is a system configuration diagram of an internal combustion engine in the embodiment.

FIG. 3 is a control block diagram showing a state of throttle opening control in the embodiment.

FIG. 4 is a control block diagram showing a state of idle learning control in the embodiment.

[Explanation of symbols]

1 Internal combustion engine 2 fuel injection valve 3 control unit 4 spark plugs 7 Air flow meter 8 Throttle valve 9 Throttle sensor 10 crank angle sensor 11 Water temperature sensor 12 Oxygen sensor 13 motor 14 Vehicle speed sensor 15 Neutral switch 16 electrical load switch 17 Accelerator position sensor

─────────────────────────────────────────────────── --- Continuation of the front page (72) Inventor Tayo Yoshino 2 Takara-cho, Kanagawa-ku, Yokohama-shi, Kanagawa Nissan Motor Co., Ltd. (56) References JP-A-60-261950 (JP, A) JP-A-2 -291438 (JP, A) JP-A 2-119644 (JP, A) JP-A 9-166038 (JP, A) JP-A 9-68085 (JP, A) JP-A 9-166037 (JP, A) ) JP 61-76735 (JP, A) JP 7-217470 (JP, A) JP 6-93911 (JP, A) JP 61-272444 (JP, A) (58) Field (Int.Cl. ⁷ , DB name) F02D 1/00-1/18 F02D 9/00-11/10 F02D 13/00-28/00 F02D 29/00-29/06 F02D 41/00-41 / 40 F02D 43/00-43/04 F02D 45/00 F02M 25/06-25/07 F02M 39/00-71/04 F02B 33/00-39/16

Claims (3)

(57) [Claims] 1. A target air amount is set according to operating conditions of an engine, the target air amount is converted into a target opening area of a throttle valve, and a throttle valve is opened / closed by an actuator so that the target opening area is achieved. In an electronically controlled throttle internal combustion engine equipped with an electronically controlled throttle system, idle speed feedback control means for feedback controlling the target air amount so that the engine speed approaches the target idle speed when the engine is idle, When the learning condition is satisfied, the correction air amount by the idle rotation feedback control means is calculated based on the correlation between the air amount and the opening area at the suction negative pressure under the predetermined learning condition. And an idle rotation learning unit for learning the opening area as an idle rotation learning value. An electronically controlled throttle internal combustion engine, comprising: learning correction means for correcting and setting the target opening area based on an idle rotation learning value as an opening area learned by the idle rotation learning means. Idle rotation learning control device. 2. A combustion system of the internal combustion engine is configured to be switched between stratified combustion by injection in a compression stroke and homogeneous combustion by injection in an intake stroke, and the idle rotation learning means performs a predetermined learning. The idle rotation learning control device for an electronically controlled throttle internal combustion engine according to claim 1, wherein, when a condition is satisfied, the stratified charge combustion is prohibited and learning is performed in the homogeneous combustion state. 3. The idle rotation learning control device for an electronically controlled throttle internal combustion engine according to claim 2, wherein the idle rotation learning means performs learning once at a time when the ignition switch is ON.