JP2510877B2 - Auxiliary air control device for internal combustion engine - Google Patents

Description

The present invention relates to an auxiliary air control device for an internal combustion engine.

<Prior Art> As an auxiliary air control device for an internal combustion engine, an auxiliary air control valve is provided in an auxiliary air passage that bypasses a throttle valve,
There is a system in which the opening degree of the auxiliary air control valve is increased / decreased and adjusted under idle operation conditions to control the idle speed to an optimum value.

In addition to the idle speed control function, a deceleration air-fuel ratio correction function (anti-afterburn valve function) as a measure to prevent afterburn due to air-fuel ratio enrichment during deceleration, and a negative pressure in the intake manifold during deceleration. Some are equipped with a deceleration negative pressure correction function (boost control valve function) for maintaining a constant
62362).

The deceleration air-fuel ratio correction function is the air-fuel ratio that causes the wall-flow fuel in the intake manifold to flow into the combustion chamber during deceleration when the throttle valve is fully closed due to fuel transportation delay due to fuel wall adhesion. Is concentrated in the exhaust system without being ignited, and afterburning is caused by secondary air or exhaust heat, which adversely affects the exhaust system. To prevent this, air is introduced into the intake manifold during deceleration. To do.

In addition, the deceleration negative pressure correction function means that the negative pressure in the intake manifold rises during deceleration when the throttle valve is fully closed, resulting in high boost, resulting in insufficient compression pressure and incomplete combustion, and unburned gas (HC ) Increases or causes oil to rise, so in order to prevent this, air is introduced into the intake manifold during deceleration.

In order to perform such a deceleration air-fuel ratio correction function and a deceleration negative pressure correction function, the control amount (opening) of the auxiliary air control valve is set as follows, for example.

That is, the deceleration air-fuel ratio correction amount ABV is stored in the map according to the engine intake air flow rate Q, and is set by referring to the map during deceleration. Further, the deceleration negative pressure correction amount BCV is stored in a map according to the engine speed N, and is set by referring to the map during deceleration. Then, in order to control the idle speed, the engine speed is dependent on the engine cooling water temperature, and the idle speed control basic amount is compared with the target idle speed under the ISC _TW and idle operating conditions. compared with ISC _CL or the like comprising at idling speed control component ISC _ID is set _{(= ISC TW + ISC CL +} ...), a deceleration air-fuel ratio correction amount ABV, and a deceleration negative pressure correction amount BCV,
The largest of these is selected and the control amount is set based on this.

<Problems to be Solved by the Invention> By the way, in recent years, the auxiliary air control device is forced to open the throttle valve at a low temperature in response to the engine cooling water temperature in order to downsize the auxiliary air control valve. A wax type throttle opener is provided.

Also, the deviation ΔISC _CL from the reference value for the feedback control is learned under the idle operation condition (idle speed feedback control condition), and based on this, the learning control ISC
_LR is set, and the control amount is corrected by this to absorb component variations. That is, if ISC _E is the maximum value among the three values of ABV, BCV, and ISC _ID , ISC _ON = ISC _E + ISC _LR + ... And the control amount is set based on this ISC _ON .

However, the learning control amount ISC _LR is a correction value for the deviation from the target idle speed under the idle speed feedback control condition, so the deceleration air-fuel ratio correction amount ABV
Or, when the deceleration negative pressure correction amount BCV is selected, if this is corrected by the learning control amount ISC _LR and the control amount is set, the required output for the original deceleration air-fuel ratio correction or deceleration negative pressure correction There was a problem of causing a large deviation.

That is, as shown in FIG. 4, the engine required air flow rate is divided into an opener share and an auxiliary air control valve share, and the learning control share ISC _LR is greatly influenced by the opener share (learning control share). Because ISC _LR always varies greatly depending on each water temperature due to the characteristics of the opener, etc.) There is no point in adding a correction to, and bounce occurs.

In view of such conventional problems, the present invention provides an auxiliary air control device for an internal combustion engine, which can improve the deceleration air-fuel ratio correction function and the deceleration negative pressure correction function even if there are variations in the throttle opener and the like. The purpose is to do.

<Means for Solving the Problems> Therefore, according to the present invention, as shown in FIG.
The auxiliary air control device of the internal combustion engine is configured by including the means of J to J.

(A) Auxiliary air control valve interposed in an auxiliary air passage bypassing the throttle valve (B) Deceleration air-fuel ratio correction amount setting means for setting an auxiliary air flow amount for deceleration air-fuel ratio correction according to the engine intake air flow rate during deceleration (C) Deceleration negative pressure correction amount setting means for setting deceleration negative pressure correction amount auxiliary air flow amount according to engine speed during deceleration (D) Idle speed control basic amount auxiliary air flow amount depending on engine cooling water temperature Idle speed control basic amount setting means to be set (E) Feedback control amount setting means for comparing the engine speed with the target idle speed under idle operating conditions and increasing or decreasing the auxiliary air flow rate for the feedback control based on the comparison result (F) Under idle operating conditions, the deviation from the predetermined reference value for the feedback control is learned, and the auxiliary air flow rate for the learning control is set based on this. Learning control minute setting means (G) Idle speed control minute setting means (H) for setting idle rotation speed control quantity as a sum of the idle speed control basic quantity, the feedback control quantity and the learning control quantity Selection means for selecting the largest value among the fuel ratio correction amount, the deceleration negative pressure correction amount, and the idle speed control amount. (I) The auxiliary air control valve is set by setting a control amount based on the selected value. (J) Throttle opener forcibly opening the throttle valve at low temperature in response to the engine cooling water temperature <Operation> In the above configuration, the air amount control is performed by using the throttle opener together when the temperature is low. The control range of the air amount is large when the low temperature is included, but by making the throttle opener share the air amount control at the low temperature, the auxiliary air control valve Type of becomes possible.

On the other hand, the deceleration air-fuel ratio correction amount ABV is set by the engine intake air flow rate Q, and the deceleration negative pressure correction amount BCV is set by the engine speed N, although it mainly comes to life after warming up.

In addition, ISC _TW for basic idling speed control is set according to the engine cooling water temperature, and under idle operating conditions, the engine speed is compared with the target idling speed and the feedback control ISC _CL is increased or decreased based on the comparison result. In addition, under the idle operation condition, the deviation ΔISC _CL from the reference value for the feedback control is learned and the learning control I
Set SC _LR . Then, the idle speed control basic IS
C _TW plus feedback control ISC _CL plus learning control ISC _LR , idle speed control ISC _ID (= ISC _TW + IS
C _CL + ISC _LR ) is set.

Then, the deceleration air-fuel ratio correction amount ABV, the deceleration negative pressure correction amount BCV, and the idle speed control amount ISC corrected by the learning control amount
Of the _IDs , the largest one is selected, the control amount is set based on this, and the opening degree of the auxiliary air control valve is controlled.

Thus, the deceleration air-fuel ratio correction amount ABV or the deceleration negative pressure correction amount B
When the CV is selected, the learning control amount ISC _LR is not corrected so that the CV is optimized.

<Example> An example of the present invention will be described below.

In FIG. 2, the air from the air cleaner 1 passes through an intake duct 2 and an electromagnetic auxiliary air that is interposed in a throttle valve 3 that interlocks with an accelerator pedal (not shown) and an auxiliary air passage 4 that bypasses the throttle valve 3. It is inhaled under the control of the control valve 5. Then, it is mixed with the fuel injected from the fuel injection valve 7 in the intake manifold 6 and is sucked into the engine 8.

Further, the throttle valve 3 has a temperature-sensing portion facing an engine cooling water passage (not shown), and in response to the engine cooling water temperature Tw, the throttle valve 3 is forcibly opened from the fully closed position when the temperature is low. Throttle opener 20 is attached.

The opening degree of the auxiliary air control valve 5 is controlled by a control signal from the control unit 9, and for such control, signals from various sensors are input to the control unit 9.

As the various sensors, a hot-wire air flow meter 10 is provided in the intake duct 2 to detect the intake air flow rate Q. Further, a rotation speed sensor 11 is provided, and the engine rotation speed N
To detect. A water temperature sensor 12 is provided to detect the engine cooling water temperature Tw. Further, the throttle valve 3 is provided with a potentiometer-type throttle sensor 13 to detect the throttle valve opening TVO. In addition, an idle switch 14 that turns ON when the throttle valve 3 is fully closed, and a neutral switch that turns ON when the transmission is in the neutral position
A start switch 16, which is turned on at the start position of the engine key switch, and a vehicle speed sensor 17 for detecting the vehicle speed VSP are provided.

Here, the microcomputer in the control unit 9 controls the opening degree of the auxiliary air control valve 5 by performing arithmetic processing according to the flowchart of FIG. 3 based on the signals from the various sensors.

The routine shown in FIG. 3 is executed every predetermined time (for example, 10 ms).

In step 1 (denoted as S1 in the figure. The same applies hereinafter), the intake air flow rate Q, engine speed N, water temperature Tw, throttle valve opening TVO, vehicle speed VSP, and ON / OFF signals of various switches are read.

In step 2, it is determined whether or not the idling operation condition (idle speed feedback control condition) is satisfied. Here, the idle speed feedback control condition is that the vehicle speed VSP is 8
The condition is that the neutral switch 15 is ON and the start switch 16 is OFF after the idle switch 14 is ON and after a certain time after being turned ON at km / h or less.

In the case of the idle speed feedback control condition, the process proceeds to step 3 to perform feedback control. That is, the target idle speed Ns depending on the water temperature Tw and the actual idle speed N are compared with each other, and the feedback control amount ISC _CL is increased / decreased by the well-known proportional / integral control.
This step 3 corresponds to the feedback control amount setting means.

Next, in step 4, learning is performed. That is, while learning the deviation ΔISC _CL from the predetermined reference value (usually 0) of the feedback correction amount ISC _CL, the current water temperature is read from the rewritable RAM map that stores the learning control amount ISC _LR corresponding to the water temperature Tw. The learning control component ISC _LR corresponding to Tw is read, the learning control component ISC _LR is updated based on the following equation, and the RAM map data is rewritten. The part of step 4 corresponds to the learning control amount setting means.

ISC _LR ← ISC _LR + ΔISC _CL / M (M is a constant) Next, in step 5, the deceleration air-fuel ratio correction amount ABV and the decompression / negative pressure correction amount BCV are set to 0, respectively. Then, the process proceeds to step 13 described later.

If it is not the idle speed feedback control condition, the process proceeds to step 6 and whether the throttle valve opening change amount ΔTVO, which is the difference from the previous value of the throttle valve opening TVO, is less than or equal to a predetermined value (for example, −1.6 deg / 10 ms). By determining, it is determined whether or not the vehicle is decelerating.

Except during deceleration, proceed to step 7 and set the idle switch
It is determined whether 14 is ON, and if the throttle valve 3 is open and the idle switch 14 is OFF, the process proceeds to step 8.

In step 8, the deceleration air-fuel ratio correction amount ABV is referred to by referring to the map that defines the deceleration air-fuel ratio correction amount ABV according to the intake air flow rate Q.
Set. The part of step 8 corresponds to deceleration air-fuel ratio correction amount setting means.

Next, at step 9, the deceleration negative pressure correction amount BCV is set by referring to the map in which the deceleration negative pressure correction amount BCV is determined according to the engine speed N. The step 9 corresponds to deceleration negative pressure correction amount setting means. After that, the process proceeds to step 13 described later.

When decelerating from this state, the routine directly proceeds from step 6 to step 13 which will be described later, and the deceleration air-fuel ratio correction amount ABV and the deceleration negative pressure correction amount BCV set immediately before the start of deceleration are maintained.

When the throttle valve 3 is fully closed due to deceleration (coasting state), the routine proceeds to step 10 through steps 6 and 7 to reduce the deceleration air-fuel ratio correction amount ABV by a predetermined reduction rate. Next, at step 11, the deceleration air-fuel ratio correction amount ABV is compared with 0, and when ABV <0, ABV = 0 is set at step 12.
After that, the process proceeds to step 13 described later.

Next referring to a map that defines the idle speed control basic component ISC _TW in accordance with step 13, the water temperature Tw, sets the idle speed control basic component ISC _TW. This step 13 corresponds to the idle speed control basic amount setting means.

Next, in step 14, the ISC _ID for idle speed control is set by the following equation. The part of step 13 corresponds to the idle speed control amount setting means.

ISC _ID = ISC _TW + ISC _CL + ISC _LR + ISC _AS Here, the ISC _TW set in step 13 is used. As the ISC _CL , the one set in step 3 is used during the idle speed feedback control, and the other is clamped. ISC _LR
For this, the one retrieved from the RAM map based on the water temperature Tw is used. ISC _AS is a correction amount at the time of start, while the start switch is ON (during cranking) and the start switch
It is determined corresponding to the water temperature Tw for a predetermined time after being turned off.

Next, at step 15, the deceleration air-fuel ratio correction amount ABV, the deceleration negative pressure correction amount BCV, and the idle speed control amount ISC _ID are compared, and based on the comparison result, the process proceeds to step 16, 17 or 18 to assist the largest one. The air flow rate is ISC _E (l / min). The steps 15 to 18 correspond to the selecting means.

Next, at step 19, the auxiliary air flow rate ISC _E (l / min) is added with the battery voltage correction amount ISC _VB to calculate the final auxiliary air flow rate ISC _ON (l / min) = ISC _E + ISC _VB .

Next, at step 20, the auxiliary air flow rate ISC _ON (l / min) is converted into a duty ratio DUTY (%) which is a control amount and output. The part of this step 20 corresponds to the control means.

When the duty ratio DUTY is set in this way, the pulse opening signal of the auxiliary air control valve 5 is energized by the pulse signal of this duty ratio, and thereby the opening degree is controlled to obtain the desired auxiliary air flow rate. To be

<Effects of the Invention> As described above, according to the present invention, the deceleration air-fuel ratio correction amount ABV, the deceleration negative pressure correction amount BCV, and the idle speed control amount ISC _ID (= ISC _TW + ISC _CL + ISC _LR ), select the largest one, set the control amount based on this, and control the opening of the auxiliary air control valve to adjust the deceleration air-fuel ratio correction amount ABV or deceleration negative pressure correction amount. The correction by learning control ISC _LR is not performed when BCV is selected.Therefore, even if there are variations in the throttle opener etc., it is possible to improve the deceleration air-fuel ratio correction function and the deceleration negative pressure correction function. To be

[Brief description of drawings]

FIG. 1 is a functional block diagram showing the configuration of the present invention, FIG. 2 is a system diagram showing an embodiment of the present invention, FIG. 3 is a flow chart showing the contents of control, and FIG. 4 is a description of conventional problems. FIG. 3 ... Throttle valve, 4 ... Auxiliary air passage, 5 ... Auxiliary air control valve, 7 ... Fuel injection valve, 8 ... Engine, 9 ... Control unit, 10 ... Air flow meter, 11 ...
Rotation speed sensor, 12 …… Water temperature sensor, 13 …… Throttle sensor, 14 …… Idle switch, 20 …… Throttle opener

Claims (1)

(57) [Claims] 1. An auxiliary air control valve interposed in an auxiliary air passage bypassing a throttle valve, and a deceleration air-fuel ratio correction amount setting for setting a deceleration air-fuel ratio correction auxiliary air flow amount according to an engine intake air flow rate during deceleration. Means, a deceleration negative pressure correction amount setting means for setting deceleration negative pressure correction amount according to the engine speed during deceleration, and an auxiliary air flow amount for idle speed control basic amount according to the engine cooling water temperature An idle speed control basic amount setting means, a feedback control amount setting means for comparing the engine speed with a target idle speed under idle operating conditions, and increasing or decreasing the auxiliary air flow rate for feedback control based on the comparison result, A learning system that learns the deviation of the feedback control from the predetermined reference value under idle operating conditions and sets the auxiliary air flow rate for the learning control based on this. A minute setting means, an idle speed control minute setting means for setting an idle speed control amount as a sum of the idle speed control basic amount, the feedback control amount and the learning control amount, and the deceleration air-fuel ratio correction amount Selection means for selecting the largest value of the deceleration negative pressure correction amount and the idle speed control amount, and a control amount is set based on the selected value to control the opening degree of the auxiliary air control valve. And a throttle opener forcibly opening the throttle valve at low temperature in response to the engine cooling water temperature.