JPH01106956A - Control method for driving current of idling intake-air quantity control valve - Google Patents

Abstract

PURPOSE:To prevent engine stall at the time of sudden increase in load by increasing a control gain when a deviation from a target value is above a defined level at the time of feedback controlling a valve driving current fed to an idling intake-air quantity control valve to a target value. CONSTITUTION:A control unit 2 operates a target current value corresponding to the target opening of an idling intake-air quantity control valve 1 based on the detected value of an electric load signal, a water temperature sensor, an idling switch, an air-conditioner switch, etc. An actual current fed to the idling intake-air quantity control valve 1 is detected via a current detecting resistor, and feedback controlled to be a target current value via a power transistor 3. When the deviation between the actual current and the target current value is above a defined level, a control gain is made larger to rapidly increase a current fed to the idling intake-air quantity control valve 1.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to the control of the intake air amount of an engine during idling operation of an automobile, and more particularly, to a drive current control method for an idle intake air amount control valve. .

[Conventional technology]

In recent years, in the field of internal combustion engines for automobiles, with the advancement of electronic control technology for engines, electronic control technology has also been introduced for the idle speed.

This type of idle control device generally has an idle bypass passage that bypasses the throttle valve in the intake passage of the engine, and an idle intake air amount control valve (
A method is adopted in which an idle intake air amount is controlled by adjusting the opening degree of the ISO valve.

As the ISO valve, for example, a solenoid valve, a stepping motor, or the like, which opens the valve by passing a drive current through an excitation coil, is used. The target drive current value (target current value) of the ISC valve is set in advance in accordance with the engine cooling water temperature,
Idle opening degree (idle intake air amount) that always corresponds to the water temperature condition
Furthermore, the idle speed is set to be maintained.

Furthermore, when the engine load increases due to electrical load or air conditioner operation, it is necessary to increase the amount of engine intake air, so the target current value is corrected in response to such changes in engine load. ing.

When controlling the drive current of the ISO valve,
The valve drive current value of the ISO valve is detected and feedback control is performed so that the actual current value becomes a preset target current value.

A conventional example of idle intake air amount control is disclosed in, for example, Japanese Unexamined Patent Publication No. 160138/1983.

[Problem that the invention seeks to solve]

By the way, as mentioned above, when performing feedback control of the NSC valve drive current, normally closed loop control (for example, proportional-integral control) is performed based on the deviation between the actual current value and the target current value.
However, if this deviation becomes too large, feedback control may not be able to be performed in time, resulting in problems such as engine stalling.

For example, after high-load operation of the engine, the resistance of the excitation coil of the ISG valve drive system increases due to high temperature, and as a result, even if the set voltage is applied to the excitation coil, the drive current value (actual current) significantly reduced. In the worst case, the deviation between the actual current value and the target current value becomes extremely large, and feedback control cannot be performed in time.As a result, the electromagnetic force for driving the ISO valve weakens, causing fluctuations in the ISO valve opening. For example, if the ISO valve moves closer to the closing direction than the target opening), the engine intake amount at idle decreases,
Engine stall etc. may occur. In addition, when the electrical load suddenly increases during idling operation, the target current value of the SC valve is corrected, but in this case too, when the electrical load fluctuates, the battery voltage temporarily drops suddenly, causing the valve drive current to change. has decreased significantly,
As a result, a situation similar to the above-mentioned case of increased coil resistance may occur.

The present invention has been made in view of the above points, and its purpose is to change the actual current value of the ISO valve and the target current value by changing the resistance of the excitation coil of the ISC valve drive system and by sudden electrical load fluctuations. Even if the value deviation becomes large, NS
It is an object of the present invention to provide an ISC valve drive current control method that enables smooth feedback control of the C valve drive current and appropriate idle rotation speed control.

[Means for solving problems]

The above purpose is to operate an ISO valve whose opening is controlled in accordance with the value of the valve drive current to adjust the idle intake amount of the engine, and to detect the valve drive current value and set the actual current value in advance. and a control system that performs feedback control to reach a target current value, when the deviation between the actual current value and the target current value becomes larger than a predetermined level, the feedback control is performed. The gain is made larger than the normal control gain when the deviation is below a predetermined level, and the actual current value is made larger than the target until the actual current value reaches or approaches the target current value. This is achieved by feedback controlling the valve drive current using this large gain.

[Effect]

Feedback control gains include, for example, P (proportional), (integral), etc., and such control gains have a characteristic that the larger the gain, the faster the control speed becomes. In order to utilize this characteristic effectively and efficiently, the present invention adjusts the control gain when the deviation between the actual current value and the target current value exceeds a predetermined value in feedback control of the drive current of the ISC valve. The control gain is set to a value larger than normal, and the control gain is used to control the drive current to the target current value, and when it reaches the target value or approaches the target value, it is returned to the normal control gain (standard gain). As a result, due to changes in the coil resistance of the control valve or sudden electrical load fluctuations, the degree of decrease in the actual current value of the ISO valve becomes temporarily large, and the deviation between the actual current value and the target current value becomes larger than the normal level. However, the feedback control speed can be increased to smoothly bring the actual current value to the target current value, and as a result, the opening area of the ISC valve and thus the idle intake air amount can be held constant according to the engine condition. Rotational fluctuations during idling can be effectively suppressed.

〔Example〕

Embodiments of the present invention will be described based on the drawings.

FIG. 1 is a configuration diagram of an idle rotation speed control system to which the present invention is applied.

In Fig. 1, 1 is an ISC valve, 5 is a throttle valve, and 8 is a throttle valve.
Reference numeral 9 indicates an intake passage of the engine, and numeral 9 indicates an idle bypass passage that bypasses the throttle valve 5. In this bypass passage 9, an NSC valve 1 for adjusting the idle intake air amount is disposed. The NSC valve 1 is composed of an electromagnetic valve that uses an excitation coil as its valve drive mechanism, and the valve body is attracted upward in proportion to the value of the drive current applied to the excitation coil, and the valve body is attracted upward in proportion to the degree of attraction of the valve body. As a result, the opening area A increases. And throttle valve 5
During idling operation when the ISC valve 1 is fully open, the amount of intake air changes depending on the opening area A of the ISC valve 1.

2 is a microcomputer, a power transistor for current control; 3. This is a control unit composed of a current detection circuit 4 and the like.

The I10 port, which is a microcomputer element in the control unit 2, receives electrical load signals such as headlights, engine coolant detected by a water temperature sensor, air conditioner switch, air conditioner compressor switch, etc. , based on these input signals, the CPU calculates a preset and stored target idle air amount (the target idle air amount is stored as a data map converted into a target drive current value of the ISC valve), The current control signal resulting from the calculation is
It is input to the base of the power transistor 3 via the ◯ port.

The current control signal input to the base of the power transistor 3 consists of either a signal that changes the analog waveform voltage or a pulse duty ratio, and by variable control of these signals, the ISC valve 1 that passes through the power transistor 3
The drive current of is controlled.

The current detection circuit 4 is a component of a drive current feedback control system, and is composed of a current detection resistor and a differential amplifier (amplifier) 7. The drive current of the ISC valve 1 is detected by this current detection circuit 4, and this actual current value is I1
Input to port 0. Then, the CPU in the control unit 2 calculates a deviation between this actual current value and a preset target current value for idle intake air amount control, corrects the control signal for the power transistor 3 in accordance with this deviation, and controls the ISC. Feedback control is performed so that the drive current of the valve 1 becomes a target current value.

Figure 2 shows the target current value i corresponding to the engine cooling water temperature Tw.
In the characteristic diagram of 0, as the water temperature Tw becomes lower, the amount of air absorbed during idling is increased to achieve a higher idling speed as shown in FIG.

This characteristic allows stable idling without stalling even when the engine is cold. Note that the target current value for the engine cooling water temperature in Figure 2 is a basic characteristic value, and the engine load increases when there is an increase in electrical load or when an air conditioner is used, and the set idle speed cannot be maintained with the above basic characteristic values alone. On this occasion, the microcomputer C
The PU adds a load correction value to the basic characteristic value in response to an increase in the engine load, corrects the target current value, and allows the engine intake amount to increase in response to changes in the engine load.

Therefore, when performing idle speed control, a control signal of a target current value corresponding to the engine water temperature state, air conditioner operating state, etc. is input to the power transistor 3, and the drive current controlled by the power transistor 3 This is done by controlling the opening of the NSC valve 1. Also, IS
The drive current of the C valve 1 is detected by a current detection circuit 4, and based on the deviation between the actual current value and the target current value, a control signal is sent to the power transistor 3, and thus feedback control of the valve drive current is performed.

In this embodiment, when the deviation Δi between the actual current value and the target current value is below the preset reference level Δi (+) during feedback control, as shown in FIG.

As shown in Figure 5, each gain characteristic [Figure 4 is the P (proportional) component of the current value feedback control gain, and Figure 5 is the characteristic diagram of the integral (integral) component], normally Po, Io Immediately after the deviation Δi exceeds Δio, control is performed using PL and It, which are set in advance to be larger than Po and Io, until Δi becomes smaller than the deviation Δ11, which approaches the target value.

Here, the gains Po, Io, Px, and Iz are set to appropriate gains based on experimental data obtained in advance to determine how the drive current during idling operation fluctuates in various situations.

Next, an example of feedback control based on the gains pO, Io and Pi, It will be explained with reference to FIG.

FIG. 6 shows a factor that increases the engine load during idling operation. This shows the status of ISO valve current control when electrical loads such as various motors and headlights are turned on. As shown in the figure, during idle operation, the deviation Δi between the normal actual current value and the target current value is at the set level Δio. In this case, control gains po and Io are used. However, when the electrical load is turned on, the battery voltage suddenly drops temporarily immediately after the electrical load is turned on, so the ISO valve drive flow also temporarily decreases to a large extent, and the target current value jumps up. Immediately after turning on, the deviation Δi between the actual current value and the target value is the normal allowable deviation Δi.

may exceed. And in this case, Δi=Δ
Normal control gain PO until 11.

Feedback control of the current value is performed with a gain Pt, 11, which is larger than Io.

FIGS. 7 and 8 are flowcharts by a microcomputer for realizing the above feedback control, and based on these flowcharts, the feedback control of this embodiment will be explained in more detail. The program is activated at predetermined intervals.

First, in step 10, the engine cooling water temperature Tw and current value i are detected, and in step 11, a target current value io corresponding to the water temperature Tw is searched from the characteristics shown in FIG. Then, in steps 12 to 21, the correction amount 11y l 2+ l ay of the eye #A current value according to each load signal is determined, and this is
o to calculate the final target current value is. Next, in step 22, the deviation Δi is determined, and in step 23, the control gains Pa, Io or Pz, I are searched according to Δi. Next, it is checked whether the flag is set in step 24 of FIG. 8, and if NO, it is determined in step 25 whether the absolute value of the deviation 1Δ11 is greater than the determination level Δio, and if YES, the flag is set in step 26. If No, proceed to step 29.

When the flag is set in step 26, it is determined whether the deviation Δi is positive or negative in step 32. If it is positive, it is assumed that the actual current of the ISG valve is flowing too much, and in step 33 the # control gain Pz, It is determined. If the value is negative, it is assumed that the actual current is insufficient, and control to increase the drive current is performed using control gains Px and Iz in step 34.

If the flag is set in step 24, the deviation Δj when 1Δ11 approaches the target value is determined in step 27.
It is checked to see if it is smaller than 1. If YES, the flag is cleared in step 28, and if NO, the process proceeds to step 32. When the flag is cleared in step 28, it is determined whether Δ1 is positive or negative in step 29, and then drive current reduction control is performed using normal control gains Pa and Io (step 31), or Drive current increase control (step 30) is performed.

Also, in step 25, the deviation 1Δ11 is determined by the judgment level Δ
Even when it is smaller than io, the normal control gains Po and I are determined in step 29°30.31.

Feedback control of the current value is performed.

As described above, according to the present embodiment, the current value flowing through the ISC valve is feedback-controlled, and when the current value suddenly changes, the control gain is made larger than usual until the target value is reached or approached. Therefore, even if the feedback control current value deviation Δi varies greatly due to changes in the electrical load of the engine, temperature rises in the excitation coil resistance for driving the valve, etc., smooth feedback control of the ISO valve drive current is possible. The accuracy of idle rotation speed control can be improved by reducing intake air amount fluctuation during idle.

〔Effect of the invention〕

As described above, according to the present invention, since the feedback control gain is made different depending on the deviation level, the actual current value of the ISO valve and the target current value are Even if the deviation becomes large, feedback control of the NSC valve drive current can be performed smoothly, and appropriate idle rotation speed control can be performed.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of an idle speed control system according to an embodiment of the present invention, and Fig. 2 shows the relationship between the engine cooling water temperature and the NSC valve drive current value (target current value) used in the above idle speed control system. Characteristic diagram, Figure 3 is the above NSC
Characteristic diagram of engine speed when valve drive current is applied, No. 4
5 and 5 are gain characteristic diagrams when the NSC valve drive current of the above embodiment is feedback-controlled, and FIG. 6 is a gain characteristic diagram of the NSC valve drive current of the above embodiment.
Waveform diagrams showing the feedback control operation of the C valve drive current, and FIGS. 7 and 8 are flowcharts for executing the feedback control operation. DESCRIPTION OF SYMBOLS 1...■SC valve, 2...Control unit (feedback control system), 3...Power transistor for drive current control, 4...Current detection circuit, 5...Throttle valve, 8... Intake passage, 9... Idle bypass passage.

Claims (1)

[Claims] 1. An idle intake amount control valve whose opening is controlled in accordance with the value of the valve drive current to adjust the idle intake amount of the engine, and an actual current value of the valve drive current is detected, and this actual current value is and a control system that performs feedback control so as to reach a preset target current value, and when the deviation between the actual current value and the target current value becomes larger than a preset predetermined level, the The feedback control gain is made larger than the normal control gain when the deviation is below a predetermined level, and the valve driving current is controlled by this large control gain until the actual current value reaches or approaches the target current value. A drive current control method for an idle intake air amount control valve characterized by feedback control.