JPH09126022A - Idling rotational speed learning control device of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the mistaken learning of the learned value, and to provide the technology to improve the learning accuracy by prohibiting the simultaneous operation of the learning of the idling speed and the EGR. SOLUTION: S1 judges whether or not the condition to perform the learning is established. More concretely, a judgment is made that the learning is possible when the feedback control of the idling speed is realized, the temperature of the cooling water is above the prescribed value, and the battery voltage is within the prescribed range, and if the condition is established, the process is advanced to S2, or the routine is finished if the condition is not established. At S2 a judgment is made whether or not the condition to realize EGR is established. More concretely, a judgment is made by retrieving the EGR characteristic map based on the flow rate of the sucked air and the engine rotational speed, and if the condition is established, the routine is finished. If the condition is not established, the process is advanced to S3. Because the learning condition is established and the EGR condition is not established in S3, the air leakage is learned, and the routine is finished.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for learning a control value when a target rotation speed is obtained while controlling an idle rotation speed of an internal combustion engine, and more particularly to learning for performing exhaust gas recirculation during idle operation. Control technology.

[0002]

2. Description of the Related Art As an idle speed control device for an internal combustion engine, for example, as disclosed in Japanese Patent Laid-Open No. 62-129544, an auxiliary air passage for bypassing a throttle valve provided in an intake system of the engine is provided. In addition to providing an electromagnetic idle control valve in this auxiliary air passage, the intake air flow rate is controlled by controlling the opening and closing of this idle control valve so that the actual idle rotation speed approaches the target rotation speed. Some have feedback control.

In such an idle speed control device, however, the control value of the intake air flow rate is changed from the initial state due to the friction of the engine, the variation in the clearance between the throttle valve and the inner wall surface of the intake passage, and the deterioration thereof with time. It will change. Therefore, it is generally performed that the control value is sequentially learned and stored as a learned value, and the learned value is used as a control initial value to reduce the rotational speed fluctuation immediately after the start of the feedback control. .

From the viewpoint of environmental protection and improvement of fuel consumption,
A part of the exhaust gas is introduced into the intake system for recirculation, and this is mixed with the combustion mixture to lower the combustion temperature, thereby reducing NOx.
There is an exhaust gas recirculation (hereinafter abbreviated as “EGR”) technique for reducing the amount of the exhaust gas generated and improving the thermal efficiency by improving the cycle efficiency.

[0005]

However, the learning of the idle speed (hereinafter abbreviated as learning) and the EG
When performing R and R at the same time, as shown in FIG.
Since the intake negative pressure and the intake air flow rate required at the time of idling change according to the rate (EGR amount), there is a possibility that it may be a factor of erroneous learning of the learning value.

In view of the conventional problems as described above, the present invention prevents the learning of the idle speed and the EGR from being performed at the same time, thereby preventing the erroneous learning of the learning value. The purpose is to provide a technique for improving learning accuracy.

[0007]

Therefore, according to the invention as set forth in claim 1, as shown in FIG. 1 (a), the intake air flow rate is feedback-controlled so as to reach the target rotation speed during idle operation of the engine. An idle rotation speed learning control device that learns a control value when the target rotation speed is obtained, and an exhaust gas recirculation device that recirculates a part of the exhaust gas of the engine to the intake system are learned under predetermined conditions. In a vehicle that simultaneously performs the exhaust gas recirculation and the exhaust gas recirculation, a learning condition determining unit that determines whether a condition for learning the control value is satisfied, and a condition for performing the exhaust gas recirculation are determined. Exhaust gas recirculation condition determination means, the learning condition is satisfied, and
A learning permission unit that permits the learning of the control value when the exhaust gas recirculation condition is not established.

In this way, since the exhaust gas recirculation is not performed while the control value is being learned, the control value learning and the exhaust gas recirculation are not performed at the same time. In the invention according to claim 2, as shown in FIG. 1B, instead of the exhaust gas recirculation condition determination means and the learning permission means, an exhaust gas recirculation rate calculation means for calculating an exhaust gas recirculation rate and an exhaust gas recirculation are prohibited. Exhaust gas recirculation prohibition means and learning permission control for prohibiting exhaust gas recirculation by the exhaust gas recirculation prohibition means and permitting learning of the control value when the learning condition is satisfied and the exhaust gas recirculation rate is less than a predetermined value. And means.

With this configuration, the control value is learned even when the exhaust gas recirculation rate is less than the predetermined value, that is, when the exhaust gas recirculation rate is low, even under the condition that the exhaust gas recirculation is performed.
The learning frequency of the control value is improved. The invention according to claim 3 is
The learning permission control means, when the learning condition is satisfied, the exhaust gas recirculation rate is less than a predetermined value, and the number of learning times of the control value after engine start is less than a predetermined value, the exhaust gas recirculation prohibition means. Thus, the exhaust gas recirculation is prohibited and the learning of the control value is permitted.

With this configuration, even when the exhaust gas recirculation condition is satisfied and the exhaust gas recirculation rate is low, the control value is learned a predetermined number of times or more, that is, when the learning number is large, the control value is large. Is prohibited, and exhaust gas recirculation is started.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. In FIG. 2 showing a system configuration of an embodiment of an idle speed learning control device according to the present invention, air is sucked into an internal combustion engine 1 through an air cleaner, an intake duct 2 and an intake manifold 3 which are not shown. The intake duct 2 is provided with a throttle valve 4 interlocking with an accelerator pedal (not shown) to control the intake air flow rate Q. Further, an idle control valve 6 is provided in an auxiliary air passage 5 provided by bypassing the throttle valve 4.

Here, as the idle control valve 6, for example, one having a structure including a valve opening coil and a valve closing coil is used. A drive pulse signal (opening control signal) from a control unit 7 having a built-in microcomputer is sent to each of the coils in a mutually inverted state, and the duty ratio of the drive pulse signal ( The opening degree of the idle control valve 6 is controlled by the energization time ratio (% to the valve opening coil), and the engine intake air flow rate Q during idle operation is controlled by this opening degree, so that the engine rotation speed becomes a predetermined value. Is controlled.

On the other hand, fuel is intermittently injected from a fuel injection valve 8 installed in the intake manifold 3 in synchronism with engine rotation, mixed with the intake air and sucked into the cylinder. Further, as a configuration that performs the EGR function, an EGR passage 10 that connects the exhaust manifold 9 and the intake manifold 3 of the internal combustion engine 1 is provided, and the EGR passage 10 is opened and closed by an EGR control valve 11. It has become. The EGR control valve 11 is a diaphragm-type valve that is closed by exerting suction negative pressure on the engine against the biasing force of the coil spring in the valve closing direction. A negative pressure introducing passage 12 which communicates with the intake duct 2 on the downstream side is provided, and the intake negative pressure of the internal combustion engine 1 is introduced into the pressure chamber through the negative pressure introducing passage 12 to open the valve.

An EGR control solenoid 13 whose opening is controlled by the duty ratio of the drive pulse signal from the control unit 7 is interposed in the negative pressure introducing passage 12. The EGR control solenoid 1
The EGR control valve 1 through the opening degree control of 3
The opening degree of 1, that is, the EGR amount can be controlled.

Reference numeral 14 is a diaphragm type BPT valve which determines the negative pressure for controlling the EGR control valve 11 by operating the diaphragm by the exhaust pressure and the negative pressure of the manifold. Further, signals from various sensors are input to the control unit 7 in order to determine the duty ratios of the drive pulse signals of the idle control valve 6 and the EGR control solenoid 13.
The various sensors include an air flow meter 15 installed in the intake duct 2 on the upstream side of the throttle valve 4 for detecting the intake air flow rate Q, and a rotation speed sensor 16 for extracting the rotation signal from the crankshaft to detect the engine rotation speed N. ,
An idle switch 17, which is attached to the throttle valve 4 and is turned on at the idle position (fully closed position) of the throttle valve 4,
A water temperature sensor 18 provided in the water jacket of the internal combustion engine 1 for detecting a cooling water temperature T _W representative of the engine temperature, a voltage sensor 19 for detecting a potential difference V _B between both terminals of a battery (not shown), and the like are provided. Has been.

By the way, in the above-described system, the idle control valve 6 controls the engine rotation speed N detected by the rotation speed sensor 16 to be the cooling water temperature detected by the water temperature sensor 18 when the idle switch 17 is in the idle state. Feedback control is performed by a control signal from the control unit 7 so as to approach the target rotation speed N ′ set based on T _W. The opening control amount of the idle control valve 6 is based on the cooling water temperature T _W , the engine rotation speed N, the battery voltage V _B detected by the voltage sensor 19, the operating state of auxiliary equipment such as an air conditioner (not shown), and the like. This is performed by the control unit 7 changing the duty ratio of the pulse signal supplied to the idle control valve 6.

The learning condition judging means is composed of the control unit 7, the water temperature sensor 18 and the voltage sensor 19, and the exhaust gas recirculation condition judging means and the exhaust gas recirculation rate calculating means are the control unit 7, the air flow meter 15 and the rotation speed sensor. The exhaust gas recirculation prohibition means is composed of the control unit 7 and the EGR control solenoid 13. Further, the learning permission means and the learning permission control means are composed of the control unit 7.

Further, in the feedback control immediately after starting the idle operation, in order to prevent instability of the engine operation due to the delay of the feedback control, the clearance between the throttle valve and the inner wall surface of the intake passage in the initial state is preset. By setting an air leakage amount (hereinafter abbreviated as air leakage amount) and subtracting a control amount corresponding to this air leakage amount from the opening control amount of the idle control valve 6, feedback control immediately after the start of idle operation is performed. I try to reduce the amount. In addition to this, for example, considering that dirt adheres to the inner wall surface of the intake passage and the amount of air leakage changes, learning is performed to update the control value corresponding to this amount of air leakage as needed.

However, although there is no problem when such learning of the air leakage amount is carried out independently, when EGR is carried out simultaneously, as described above, the EGR rate (EGR amount).
The intake negative pressure and the intake air flow rate required at the time of idling change in accordance with the above, which may cause erroneous learning of the learning value (see FIG. 6). Therefore, a first embodiment of the learning control content of the air leakage amount that solves such a problem will be described with reference to the flowchart of FIG. It should be noted that this learning control is executed at regular time intervals (for example, every 100 msec).

In step 1 (abbreviated as S1 in the figure, the same applies hereinafter), it is determined whether or not the conditions for learning are satisfied. Specifically, the feedback control of the idle rotation speed is being executed, the cooling water temperature T _W detected by the water temperature sensor 18 is equal to or higher than a predetermined value (T _W ≧ T ₁ ), and detected by the voltage sensor 19. When the determined battery voltage V _B is within a predetermined range (V ₁ ≤V _B ≤V ₂ ), it is determined that learning is possible. In short, when the warm-up operation of the engine is completed and the battery voltage is stable, it is considered that the idle rotation speed is stable. Therefore, the learning is performed only in such a state. And
If the learning condition is satisfied, the process proceeds to step 2, and if the learning condition is not satisfied, this routine is ended. The process of step 1 corresponds to the learning condition determining means.

In step 2, it is judged whether or not the condition for performing EGR is satisfied. Specifically, the determination is made, for example, by searching an EGR characteristic map based on the intake air flow rate Q (corresponding to the engine load) detected by the air flow meter 15 and the engine rotation speed N detected by the rotation speed sensor 16. To do. If the EGR condition is satisfied (EGR is performed), this routine is ended, and the EGR
If the condition is not satisfied (EGR is not performed) Step 3
Proceed to. The processing of step 2 corresponds to the exhaust gas recirculation condition determination means, and the processing of steps 1 and 2 also corresponds to the learning permission means.

In step 3, the learning condition is satisfied, and
Since the EGR condition is not satisfied, the air leakage amount is learned and this routine ends. If the learning control described above is performed, learning of the air leakage amount and EGR will not be performed at the same time, and this is caused by a change in the intake negative pressure according to the EGR rate (EGR amount) and the intake air flow rate required during idling. Erroneous learning of the learning value is prevented, and thus the learning accuracy is improved.

FIG. 4 shows a second control content of the learning control of the air leakage amount.
It is a flowchart which shows the Example of FIG. This learning control is also executed at regular time intervals (for example, every 100 msec). In step 10, it is determined whether or not a learning condition is satisfied. If the learning condition is satisfied, the process proceeds to step 11. If the learning condition is not satisfied, this routine is ended. This process is the same as the process of step 1 in the first embodiment, so refer to the description of step 1 for details.

In step 11, the EG when performing EGR
Calculate the R rate. Specifically, based on the intake air flow rate Q (corresponding to the engine load) detected by the air flow meter 15 and the engine rotation speed N detected by the rotation speed sensor 16, for example, by searching an EGR characteristic map, EGR is performed. EG is calculated from this and the intake air flow rate Q
Calculate the R rate. The processing of step 11 corresponds to the exhaust gas recirculation rate calculation means.

In step 12, it is judged whether the EGR rate is high or low, that is, whether the EGR rate is a predetermined value or more, and E
If the GR rate is equal to or higher than a predetermined value (EGR rate: high), this routine is ended to give priority to the EGR, and if the EGR rate is less than the predetermined value (EGR rate: low), the learning of the air leakage amount is prioritized. Then, the process proceeds to step 13 to be performed. The processing of steps 10 to 12 corresponds to the learning permission means.

At step 13, since the learning of the air leakage amount is given priority, the EGR is prohibited so that the EGR is not performed. Specifically, the EGR control solenoid 1
This is realized by setting the duty ratio of the drive pulse signal to 3 to 0. The process of step 13 corresponds to the exhaust gas recirculation prohibition means. In step 14, the amount of air leakage is learned. In the following step 15, it is judged whether or not the learning of the air leakage amount has been performed for a predetermined time or a predetermined number of times, that is, whether or not the learning has ended. If the learning has not ended, the process returns to step 14 to perform the learning. If it is completed, the process proceeds to step 16. In short, in the processing of steps 14 and 15, learning of the air leakage amount is performed for a predetermined time (number of times) to improve the learning accuracy.

At step 16, since the learning of the air leakage amount is completed, the prohibition of EGR is canceled so that the EGR prohibited at step 13 is performed. When the learning control described above is performed, even if the EGR is performed, the EG
When the R ratio is low, the EGR is prohibited and the learning of the air leakage amount is performed, so that the learning frequency of the air leakage amount is improved as compared with the first embodiment, and thus the learning accuracy is further improved. .

FIG. 5 shows a third control content of the learning control of the air leakage amount.
5 is a flowchart showing an embodiment of the second embodiment shown in FIG.
The control contents of the above embodiment are further improved. This is step 1 in the flowchart of FIG. 4 described above.
Since the processing is added between 2 and 13, and the processing contents other than this are exactly the same as those described above, the description thereof will be omitted here and only the added processing contents will be described.

In step 12-1, the number of learnings of the air leakage amount after the internal combustion engine 1 is started is checked, and if the number of learnings is a predetermined number or more (learning number: many), EGR should be preferentially performed. When this learning is completed and the number of learning is less than the predetermined number (learning number: small), the routine proceeds to step 13 to prioritize learning of the air leakage amount. The number of times of learning the air leakage amount may be set, for example, by providing a timer that is reset to 0 when the internal combustion engine 1 is started and increasing the value each time the learning is performed.

When the learning control described above is performed, even if the EGR is performed and the EGR rate is low, if the number of times of learning is large, the learning is not performed.
Since R is preferentially performed, it is possible to avoid deterioration of drivability and emission while ensuring the learning accuracy of the air leakage amount.

[0031]

As described above, according to the first aspect of the present invention, the control value is not learned when the condition for performing the exhaust gas recirculation is satisfied. Therefore, the learning is performed during the exhaust gas recirculation. It is possible to prevent erroneous learning due to, and thus improve learning accuracy. According to the second aspect of the invention, even if the exhaust gas recirculation is performed, when the exhaust gas recirculation rate is less than the predetermined value, that is, when the exhaust gas recirculation rate is low, the exhaust gas recirculation is prohibited and the control value is learned. Therefore, the learning frequency of the control value is improved, and thus the learning accuracy can be improved.

According to the third aspect of the present invention, even when the exhaust gas recirculation is performed and the exhaust gas recirculation rate is low, the control value is learned a predetermined number of times or more, that is, the learning number is When the number is large, the control value is not learned, and the exhaust gas recirculation is prioritized. Therefore, it is possible to avoid deterioration in drivability and emission while ensuring learning accuracy.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of the present invention, in which (a) is a claim;
2 shows a block diagram according to the described invention, and (b) shows a block diagram according to the invention as claimed in claim 2.

FIG. 2 is a system configuration diagram showing an embodiment of an idle rotation speed learning control device according to the present invention.

FIG. 3 is a flowchart as a first embodiment showing the learning control contents of the above.

FIG. 4 is a flowchart as a second embodiment showing the learning control contents of the above.

FIG. 5 is a flowchart as a third embodiment showing the learning control contents of the above.

FIG. 6 is a diagram showing a problem of a conventional idle rotation speed learning control device.

[Explanation of symbols]

 3 Intake Manifold 5 Auxiliary Air Passage 6 Idle Control Valve 7 Control Unit 9 Exhaust Manifold 10 EGR Passage 11 EGR Control Valve 12 Negative Pressure Introduction Passage 13 EGR Control Solenoid 15 Air Flow Meter 16 Rotation Speed Sensor 17 Idle Switch 18 Water Temperature Sensor

Claims (3)

[Claims] 1. An idle rotation speed learning control device for learning a control value when the target rotation speed is obtained while feedback-controlling an intake air flow rate so as to attain the target rotation speed during idle operation of the engine, and an exhaust gas of the engine. An exhaust gas recirculation device that recirculates a part of the exhaust gas to the intake system, and in a vehicle that simultaneously learns the control value and exhaust gas recirculation under predetermined conditions, determines whether the condition for learning the control value is satisfied. A learning condition determining means for determining, and an exhaust gas recirculation condition determining means for determining whether a condition for performing the exhaust gas recirculation is satisfied, and the learning condition is satisfied, and when the exhaust gas recirculation condition is not satisfied, An idle speed learning control device for an internal combustion engine, comprising: learning permission means for permitting learning of the control value. 2. An exhaust gas recirculation rate calculation means for calculating an exhaust gas recirculation rate, an exhaust gas recirculation prohibition means for prohibiting exhaust gas recirculation, and the learning condition are satisfied in place of the exhaust gas recirculation condition determination means and the learning permission means. Further, when the exhaust gas recirculation rate is less than a predetermined value, the exhaust gas recirculation prohibiting unit prohibits exhaust gas recirculation, and a learning permission control unit that permits learning of the control value is included. The idle speed learning control device for an internal combustion engine according to claim 1. 3. The learning permission control means, when the learning condition is satisfied, the exhaust gas recirculation rate is less than a predetermined value, and the number of learning times of the control value after engine start is less than a predetermined value,
3. The idle speed learning control device for an internal combustion engine according to claim 2, wherein the exhaust gas recirculation prohibiting unit prohibits exhaust gas recirculation and permits learning of the control value.