JPS63205445A - Idle rotation controller for internal combustion engine - Google Patents

Abstract

PURPOSE:To suppress variation of engine rotation effectively by setting feedback correction value of the opening of an idle control value through fuzzy reasoning, in due consideration of deviation of engine rotation from target rotation and variation rate of engine rotation. CONSTITUTION:Means B sets the basic control value of the opening of idle control valve based on an operating condition of engine detected through means A, and means C sets a target rotation of engine. Means G sets a feedback correction value of the idle control valve J through fuzzy reasoning, based on a deviation of engine rotation detected through means E and a variation rate of engine rotation detected through means F. Means H sets the final opening control value of the idle control valve J, based on the basic control value and the feedback correction value. Means I outputs an opening control signal corresponding to the setting control value of opening to the idle control valve J.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to an apparatus for controlling the idle speed of an internal combustion engine.

<Prior art> As an idle speed control device for an internal combustion engine, for example,
As shown in the figure, an idle control valve (ISC valve) 3 is provided in the middle of an auxiliary air passage 2 that bypasses a throttle valve 1, thereby adjusting the amount of auxiliary air and controlling the idle rotation speed. There is. Idle control valve 3
is a rotary set, and pulse signals are sent to a valve-opening coil and a valve-closing coil (not shown) in a mutually inverted state, and the degree of opening is adjusted according to the duty ratio of the pulse signals. In addition, 4 is an SP1 type fuel injection valve,
5 is a hot wire air flow meter, and 6 is a blow-high gas reflux pipe.

By the way, the duty ratio of the pulse signal to the idle control valve is determined by the control value l5Cdy calculated by the following equation. The unit of this control value is expressed in (%),
It is output as the percentage of time that the valve opening coil is ON.

I5Cdy=ISCtw+I5Cet+I
5Cfb Here, l5Ct- is a basic control value dependent on cooling water temperature (hereinafter referred to as water temperature), l5Cet is various correction values such as air conditioner correction and acceleration/deceleration correction, and l5Cfb is a feedback control m (IsC) of idle rotation speed, which will be described later. This is the feedback correction value for

Regarding feedback control of idle rotation speed, the target rotation speed that depends on the water temperature detected by the water temperature sensor is compared with the actual rotation speed detected by the crank angle sensor (hereinafter referred to as the actual rotation speed), and if there is a difference, Then, the control value at that time is corrected to control the target rotation speed. Therefore, the feedback correction value l5 is
We have established something called Cfb.

The feedback correction value l5CfbO value is changed by proportional-integral (PI) control to achieve stable control. That is, the target rotation speed and the actual rotation speed are compared, and if the actual rotation speed is lower (higher) than the target rotation speed, the feedback correction value l5Cfb is first increased (lowered) by P, and then Gradually rise (down) one minute at a time.

By the way, the rotation speed obtained by the open loop duty (control value ISCdy when feedback correction value I5Cfb=O) corresponding to the basic control value ISCtw (or the addition value of this and various correction values l5Cet) is the target rotation. If it perfectly matches the number, the feedback correction value l5Cfb will be O, so feedback control is not necessary. However, in reality, the correlation deviates due to clogged throttle chambers, variations in parts, etc., so feedback control is performed. ing.

<Problems to be Solved by the Invention> However, as mentioned above, during feedback control of the idle speed, the feedback control value is
In the method of setting by control, the control only takes into account the magnitude relationship between the engine speed and the target speed, so the degree of convergence to the target speed is poor, promoting hunting, and the amount of over (under) shoot is large, causing the rotation This caused problems such as engine stalling due to depression.

The present invention has been made by focusing on the above-mentioned conventional problems, and is configured to set a feedback correction value taking into consideration the rate of change in engine speed, thereby suppressing fluctuations in engine speed. An object of the present invention is to provide an idle rotation speed control device for an internal combustion engine that can control the idle speed of an internal combustion engine.

Means for Solving the Problems> For this reason, the present invention, as shown in FIG. , an idle rotation speed control device for an internal combustion engine that controls the idle rotation speed by controlling the opening of the idle control valve to control the intake air flow rate during idle operation, an engine operation state that detects an engine operation state; a detection means; a basic control value setting means for setting a basic control value of the idle control valve opening based on the engine operating condition; and a target rotation speed for setting the target rotation speed of the engine during idling operation based on the engine operating condition. A setting means, an engine rotation speed detection means for detecting the actual engine rotation speed, a rotation speed deviation detection means for detecting a deviation between the target rotation speed and the actual engine rotation speed, and a rotation speed deviation detection means for detecting the rate of change in the engine rotation speed. A rotational speed change speed detection means, a feedback correction value setting means for setting a feedback correction value for the idle control valve opening by fuzzy reasoning based on the detected rotational speed deviation and change speed, and a set basic control value. an opening control value setting means for setting a final opening control value of the idle control valve based on the feedback correction value setting means; and an opening control value setting means for setting a final opening control value of the idle control valve based on the set opening control value; The opening control signal output means outputs and controls the opening degree.

Based on the engine operating state detected by the engine operating state detection means, the basic control value setting means sets the basic control value for the opening of the idle control valve, and the target rotation speed setting means sets the target rotation of the engine. number is set.

The feedback correction value setting means determines the idle control valve opening degree by fuzzy reasoning based on the rotation speed deviation detected by the rotation speed deviation detection means and the change rate of the engine speed detected by the rotation speed change speed detection means. Set the feedback correction value.

Based on the basic control value and the feedback correction value set in this way, the opening control setting means sets the final opening control value of the idle control valve by adding these values or the like.

The opening control signal output means outputs an opening control signal corresponding to the opening control value set as described above to the idle control valve, whereby the idle control valve is controlled to the set opening. .

<Example> Examples will be described below based on the drawings.

The structure and mounting position of the idle control valve are the same as those of the conventional example shown in FIG. 4, and will be described using the same reference numerals.

FIG. 2 shows the hardware configuration of the control values.

11 is CPU, 12 is P-ROM, 13 is CMOS -
RAM 14 is an address decoder. Furthermore, R.A.
A backup power supply circuit is used for M13 in order to retain the memory contents even after the key switch is turned off.

Analog input signals to the CPU II for controlling the idle control valve 3 include the water temperature (No. H) from the water temperature sensor 5, the throttle opening signal from the throttle sensor 6, and the battery voltage from the battery 7. It is designed to be manually input via an input interface and an A/D converter 19.

20 is an A/D conversion timing controller.

Digital input signals include Idolsui Sochi 21,
There are ON/OFF signals from a neutral switch 22 and an air conditioner switch 23, and these are inputted via a digital input interface 24.

In addition, a reference signal every 180 degrees and a position signal every 1 degree, for example, from the crank angle sensor 25 are inputted via a one-shot multi-circuit 26. Further, a vehicle speed signal from a vehicle speed sensor 27 is inputted via a waveform shaping circuit 28.

The output signal (pulse signal to the idle control valve 3) from the CPtJll is sent to the valve opening coil 3a and valve closing coil 3b of the idle control valve 3 in a mutually inverted state via the phase inversion driver 29. It is ready to be sent.

Here, the CPU 11 executes the flowchart shown in FIG.
Input/output operations, arithmetic processing, etc. are performed according to a program (stored in the ROM 2) based on .

Next, the flowchart shown in FIG. 3 will be explained.

In step 1 (denoted as S in the figure), detection signals from the various sensors and switches are input.

In step 2, a basic control value ISCtw is set from the water temperature Tw detected by the water temperature sensor 15.

This setting may be performed by storing a map of the basic control value ISCtw with water aTW as a parameter in advance in the ROM 12 and searching from the map, or by calculation.

In step 3, various correction values l5Cet such as air conditioner correction and acceleration/deceleration correction are set as necessary.

In step 4, it is determined whether the ISO condition (M range where ISC feedback control is performed) is met.

Specifically, when the idle switch that detects the fully closed position of the throttle valve is ON (the throttle valve is in the fully closed position) and the neutral switch 22 is ON (the gear position of the transmission is neutral), or the idle switch 21 is ON. In addition, when the vehicle speed detected by the vehicle speed sensor 27 is less than or equal to a predetermined value, it is assumed that the ISC condition is satisfied, and the process proceeds to the next step 5.

In step 5, the engine rotation speed N is detected based on the cycle of each reference signal input from the crank angle sensor 25 or the number of position signal inputs per unit time.

That is, the crank angle sensor 25 and the function of step 5 constitute engine rotation speed detection means.

In step 6, the target rotational speed Ns is set by searching or calculating from the water temperature Tw.

The function of step 6 corresponds to target rotation speed setting means.

In step 7, the detected engine rotation speed N and the target rotation speed N are
Calculate the deviation E (=N-Ns) from s.

This step 70 function corresponds to the rotation speed deviation detection means.

In step 8, the rotation speed deviation E is set to a predetermined value of 0 (for example, ±2
0Orpm).

If the determination in step 8 is NO, that is, if the rotational speed deviation E is large, the process proceeds to step 9, where it is determined whether a fuzzy flag FFUZZY, which has a function to be described later, is 1 or 0.

If fuzzy flag FFUZZY is O, step 10
The program then proceeds to perform ISC feedback control similar to the conventional method. This is because when the rotational speed deviation E is large, the speed at which the rotational speed approaches the target rotational speed is faster in normal proportional-integral control than in feedback control based on fuzzy inference, which will be described later.

That is, in step 10, it is determined whether the deviation E is positive or negative, and E>
0 (that is, N>N s ), the process proceeds to step 11, and the feedback correction value l5Crb is increased by a predetermined amount from the previous value based on proportional-integral control (or integral control), so that E< O(N s <N ), the process proceeds to step 12 and similarly the feedback correction value l5Crb is decreased by a predetermined value tm from the previous value. E-〇 (including dead zone O)
In this case, the feedback correction value 1'3Crb is left as the previous value.

Next, the process proceeds to step 13, where the final control value l5CdV
is updated with a value obtained by adding the feedback correction value ISO, which was increased or decreased in step 11.12 or maintained at the previous value, to the previous l5Cdyo.

The function of step 13 corresponds to opening control value setting means.

In step 14, the control value 1 set in step 13 is
'S'Cd, a pulse signal (opening control signal) having a duty ratio corresponding to
It is output to b.

The function of step 14 corresponds to opening control signal output means.

In step 15, the current control value IS is used for the next calculation.
Cd, is set as the previous value l5Cdyo.

By performing conventional feedback control in this way, the engine speed approaches the target speed and in step 8
When it is determined that the deviation E is within the predetermined value, step 16
After setting the fuzzy flag FFUZZY to 1, the process proceeds to step 17 and subsequent steps to enter feedback control using fuzzy inference according to the present invention.

Also, once FFUZZY is set to 1, the ISO
Until the condition is not satisfied, even if the deviation E exceeds the predetermined value again, the process proceeds from step 9 to step 17 and subsequent steps, and feedback control based on fuzzy inference is continued.

Fuzzy inference (control) is, to put it simply, a set of certain fuzzy quantities, such as a proposition to make a manipulated variable (controlled variable) positive or negative for a certain input quantity (detected value), and A comprehensive fuzzy quantity is obtained from fuzzy quantities similarly set for different input quantities, and a positive or negative manipulated variable is set based on this fuzzy quantity.

Therefore, first, in step 17, the fuzzy quantity U is obtained by searching from the map shown in FIG. 4, when the rotational speed deviation E obtained in step 7 is used as a parameter.

Here, when the rotation speed deviation E is a positive value and large, it means that the current engine rotation speed is larger than the target rotation speed, so there is a high degree of certainty that the engine rotation speed will be controlled in a decreasing direction.
Conversely, when E is a large negative value, it is highly certain that the engine speed will be increased.

Therefore, depending on the size of the rotation speed deviation E, the fuzzy quantity U,
PB, PM, PS, O, NS, NM.

It is set to 7 stages of NB. Here, PB is the largest positive value (in the direction of increasing opening), PM is the positive intermediate value, and P'S
is the minimum positive value, 0 is the constant opening, NS is the minimum negative value (in the direction of decreasing opening), NM is the negative intermediate value, and NB is the maximum negative value, each of which corresponds to increasing or decreasing the opening. It shows the degree of certainty.

Next, in step 18, a rotational speed change rate ΔE (-N-N,) is calculated based on the difference between the engine rotational speed N detected this time and the engine rotational speed N0 detected last time.

Then, the process proceeds to step 19, where the fuzzy quantity U2 is obtained by searching from the map shown in FIG. 5, when the rotational speed change rate ΔE is used as a parameter.

In this case as well, when the rotational speed change rate ΔE is a positive value and large, it means that the speed of increase in the rotational speed is large, so it is certain that the engine speed is controlled in a decreasing direction to suppress the increase in the rotational speed. is large, and conversely, when ΔE is large and negative,
There is great certainty in increasing the engine speed.

Therefore, in this case as well, the fuzzy amount U2 is set to PB, PM, and PS depending on the thickness of the rotational speed change rate ΔE.

There are seven settings: 0, NS, NM, and NB.

Then, in step 20, each parameter E obtained in this way, a fuzzy quantity U for E,
Based on yU2, the fuzzy quantity U taking both parameters E and ΔE into consideration is searched from the map shown in FIG.

That is, when the fuzzy quantities U, , U2 are both positive and large, the fuzzy quantity U is positive and large, and UI.

When U2 is both a large negative value, it is set to a large negative value.

In step 21, the feedback correction amount I SO,b is searched from the fuzzy amount U from the map shown in FIG.

Here, the larger the positive value of the fuzzy quantity U, the more l5Cfb
The larger u is with a positive value, the larger the fuzzy quantity U is with a negative value■
5Cfbu is set to a small negative value, for example ±2
It is set in seven stages within a range of 5% (duty ratio).

In step 22, the feedback correction value 5Cfbu obtained by the fuzzy inference is set to 15Cfb.

In step 23, the current detected value N of the engine speed is set to the previous detected value N for the next calculation. Close and set.

Thereafter, the process proceeds to steps 13 to 15, and the feedback correction values ISC, , set by fuzzy reasoning as described above are calculated.
A control value 15Cdy is set using , and the control signal is output to the idle control valve 3.

In this case, the feedback correction value l is calculated by fuzzy inference.
By setting 5Cfb, the closer the engine speed is to the target engine speed Ns, and the faster the approaching speed is, the more the speed at which the engine approaches the target engine speed is reduced, and the deviation from the target engine speed is large, and As the speed in the deviation increasing direction increases, control is performed in a direction to increase the speed approaching the target rotational speed Ns.

Therefore, as shown by the chain line in Fig. 8, control is performed to gently converge to the target rotation speed while ensuring responsiveness (while suppressing an increase in the pulsation period), suppressing the amount of overshoot, and controlling the rotation speed. fluctuation 1] can be reduced, and engine stalling due to drop in rotation can be prevented.

If it is determined in step 4 that the ISC feedback control condition is not satisfied, the fuzzy flag FFUZZY is reset to O in step 24, and then the process proceeds to steps 13 and onwards, leaving the feedback correction amount ISC,, fixed at the previous value. Feedforward control is performed on the opening degree of the idle control valve 3.

<Effects of the Invention> As explained above, according to the present invention, the feedback correction value of the idle control valve opening is set by fuzzy reasoning that takes into account the deviation of the engine speed from the target rotation speed and the rate of change. , while ensuring responsiveness, the degree of convergence to the target rotational speed is good, stable rotational performance with small fluctuations can be obtained, and drop in rotational speed can be suppressed.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of the present invention, and FIG. 2 is a block diagram showing the configuration of the present invention.
FIG. 3 is a flowchart showing the control routine of the embodiment of the present invention, FIGS. 4 to 7 are various maps used for the above control, and FIG. FIG. 9 is a time chart showing the state quantity in comparison with the conventional one, and a sectional view showing the structure of the idle control valve. 1... Throttle valve 2... Auxiliary air passage 3
...Idle control valve 11...CPU 12
...P-ROM 13...CMO3-RAM
15...Water temperature sensor 25...Crank angle sensor

Claims (1)

[Claims] An idle control valve is provided in an auxiliary air passage bypassing a throttle valve installed in an intake passage of an engine,
In an idle rotation speed control device for an internal combustion engine, the idle rotation speed is controlled by controlling the opening of the idle control valve to control the intake air flow rate during idle operation. means, basic control value setting means for setting a basic control value of the idle control valve opening based on the engine operating state, and target rotation speed setting means for setting the target rotation speed of the engine during idling operation based on the engine operating state. means, an engine rotation speed detection means for detecting the actual engine rotation speed, a rotation speed deviation detection means for detecting a deviation between the target rotation speed and the actual engine rotation speed, and a rotation speed detection means for detecting the rate of change in the engine rotation speed. a feedback correction value setting means for setting a feedback correction value for the idle control valve opening by fuzzy reasoning based on the detected deviation and change speed of the rotation speed; and a set basic control value. an opening control value setting means for setting a final opening control value of the idle control valve based on the feedback correction value setting means; and outputting an opening control signal based on the set opening control value to the idle control valve. 1. An idle rotation speed control device for an internal combustion engine, comprising an opening control signal output means for controlling the opening.