JPH0734194Y2 - Auxiliary air amount control device for internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to an auxiliary air amount control device for an internal combustion engine, and more particularly to a technique for improving engine deceleration drivability by auxiliary air amount control.

<Prior Art> Conventionally, for the purpose of air-fuel ratio correction control and intake negative pressure control during deceleration operation of the engine, correction control of the auxiliary air amount supplied by bypassing the intake throttle valve (actual opening is performed. 62-162
(See Japanese Patent No. 362).

That is, an electromagnetic auxiliary air amount control valve whose opening is adjusted according to the duty ratio (valve opening control time ratio) of the drive pulse signal is provided in the auxiliary air passage that bypasses the intake throttle valve. Feedback control is performed so that the actual idle rotation speed approaches the target rotation speed.On the other hand, during deceleration operation, in addition to the duty ratio set based on the feedback control of the idle rotation speed, The duty ratio for supplying auxiliary air in order to prevent the air-fuel ratio from becoming overrich due to the fuel in the intake manifold flowing in, and the negative pressure in the intake manifold rising immediately after deceleration to increase pumping loss. To prevent this, set the duty ratio for supplying the auxiliary air amount and the duty ratio, select the maximum value from these, and Dollar rotational speed control, so as to control the auxiliary air amount control valve in the air-fuel ratio correction control and opening corresponding to those amounts auxiliary air is most often required in the intake negative pressure correction control. As a result, during engine deceleration operation, it is possible to prevent the air-fuel ratio from becoming excessively rich due to the wall-flow fuel that is lately supplied into the cylinder, and to avoid a sudden rise in suction negative pressure due to a sudden closing of the intake throttle valve. It is what

<Problems to be Solved by the Invention> By the way, like the auxiliary air amount control valve, a valve (or valve control) that is interposed in an auxiliary air passage provided by bypassing the intake throttle valve to adjust the auxiliary air amount. If the valve is in the fully open position regardless of the control request, a larger rotation of the valve will result in a larger increase in rotation. However, even if there is a failure on the fully open side, if the valve has a small capacity, its effect can be minimized. Therefore, conventionally, in addition to the duty-controlled auxiliary air amount control valve, an idle up solenoid for stepwise increasing the air amount corresponding to the load of the air conditioner is provided, and the auxiliary air amount control system is provided. Has been devised so that the capacity of each control system is minimized.

However, in the duty-controlled auxiliary air amount control valve, during the normal idle rotation feedback control, the idle up solenoid bears the load of the air conditioner, so that a relatively small amount of auxiliary air is required. However, since the amount of auxiliary air required for air-fuel ratio correction and intake negative pressure correction during deceleration operation is large, setting a capacity that satisfies the required amount during deceleration causes the auxiliary air amount control valve There is a problem that the rotation increase at the time of full open failure cannot be sufficiently suppressed, and conversely, if the capacity of the auxiliary air amount control valve is made small to suppress the rotation increase at the time of full open failure, the auxiliary air amount required during the deceleration operation is reduced. There is a problem in that the air-fuel ratio becomes overrich and deceleration shocks occur because it cannot be supplied.

The present invention has been made in view of the above problems, and an auxiliary air amount control device capable of performing desired air-fuel ratio auxiliary control and intake negative pressure correction control during deceleration operation while minimizing the capacity of the auxiliary air amount control valve. The purpose is to provide.

<Means for Solving the Problems> Therefore, in the present invention, as shown in FIG. 1, an idle-up control valve that is interposed in a first auxiliary air passage that bypasses the intake throttle valve and that opens and closes in an on / off manner is provided. An auxiliary air amount control valve which bypasses the intake throttle valve and is interposed in a second auxiliary air passage provided in parallel with the first auxiliary air passage and whose opening degree is controlled by a valve opening duty; Idle-up control means for controlling the opening and closing of the control valve based on the ON / OFF signal of the engine external load, and the valve opening duty given to the auxiliary air amount control valve is the valve opening duty for deceleration according to at least the deceleration operation condition of the engine. In the auxiliary air amount control device for an internal combustion engine, the valve opening duty setting means for setting the valve opening duty including: And a correction amount of the fuel supply amount determined by the forced open condition determination means for determining a condition for forcibly opening the idle-up control valve, and the forced open condition determination means determines the idle-up condition. An idle-up control valve for forcibly opening the idle-up control valve independently of the on / off signal of the engine external load when it is determined that the condition is a condition for forcibly opening the control valve. A forced opening control means is provided.

<Operation> That is, the idle-up control valve provided to prevent the idle rotation speed from dropping when the external load of the engine such as the air conditioner increases is controlled by the auxiliary air amount control valve according to the engine deceleration operation condition. The auxiliary air amount control valve is configured to be used, and when the required auxiliary air amount cannot be obtained only by the auxiliary air amount control valve, the idle up control valve is forcibly opened to secure the required amount. Thus, even if the capacity of the auxiliary air amount control valve is insufficient in the auxiliary air amount control during deceleration operation, desired deceleration control can be performed.

<Embodiment> An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 2, the engine 1 receives air from the air cleaner 2 through the intake duct 3, the intake throttle valve 4, and the intake manifold 5. At the branch portion of the intake manifold 5, a fuel injection valve 6 is provided for each cylinder.

The fuel injection valve 6 is an electromagnetic fuel injection valve that is energized by a solenoid to open the valve, and deenergized to close the valve. The fuel injection valve 6 is energized and opened by a drive pulse signal from a control unit 7 described later, and is not shown. Fuel that is pumped from the fuel pump and adjusted to a predetermined pressure by the pressure regulator is injected and supplied.

The auxiliary air passage 8 branched and extended from the intake duct 3 immediately upstream of the intake throttle valve 4 has two auxiliary air passages 8a, 8a on the way.
After branching to b, they are connected to the intake duct 3 downstream of the intake throttle valve 4, respectively. Here, in the auxiliary air passage 8a (first auxiliary air passage), a normally closed idle-up control valve 9 for opening and closing the auxiliary air passage 8a is turned on and off.
On the other hand, an auxiliary air amount control valve (idle control valve) 10 whose opening is adjusted by duty control is installed in the auxiliary air passage 8b (second auxiliary air passage),
These auxiliary control valves 9 and 10 provided in parallel with each other control the amount of auxiliary air supplied by bypassing the intake throttle valve 4.

The intake throttle valve 4 is provided with an opening sensor 11 for detecting the opening TVO, and an idle switch 12 which is turned on at the fully closed position (idle position) of the intake throttle valve 4. .

Further, an air flow meter 13 for detecting the intake air flow Q of the engine 1, a rotation speed sensor 14 such as a crank angle sensor for detecting the engine rotation speed N, and an engine cooling water temperature representative of the engine temperature.
A water temperature sensor 15 for detecting Tw is provided, and these detection signals are input to the control unit 7. In addition, the control unit 7 is equipped with a compressor for an air conditioner installed on the vehicle.
The ON / OFF signal is input from the air conditioning relay 16 that operates.

The control unit 7 as the idle-up control means and the valve-opening duty setting means controls ON / OFF of the idle-up control valve 9 based on each of the input signals, and a drive pulse signal sent to the auxiliary air amount control valve 10. The duty ratio (valve opening drive time ratio) is calculated to control the auxiliary air amount control valve 10 to a predetermined opening.

The idle up control valve 9 has an idle switch 12
In the engine idle operation state where it is ON, the opening control is performed when the engine external load such as the air conditioner increases to avoid a drop in the idle rotation speed. The control unit 7 has the idle switch 12 ON and When the air conditioner relay 16 is ON, the idle up control valve 9 is opened (ON).

On the other hand, the opening degree of the auxiliary air amount control valve 10 is adjusted according to the duty ratio ISCon of the drive pulse signal set according to the routine shown in the flowchart of FIG.

In step (indicated as "S" in the drawing. The same applies hereinafter) 1, the intake air flow rate Q, the engine speed N and the cooling water temperature Tw detected by the air flow meter 13, the rotation speed sensor 14 and the water temperature sensor 15 are input. .

In step 2, the duty ratio ISCabv is set. This duty ratio ISCabv is set for deceleration air-fuel ratio correction control that prevents the air-fuel ratio from becoming excessively rich during engine deceleration operation, and is set by searching from a map corresponding to the intake air flow rate Q. . Here, the duty ratio ISCabv is set to a substantially constant value when the intake air flow rate Q is equal to or higher than the predetermined intake air flow rate, but is gradually decreased when the intake air flow rate Q is equal to or lower than the predetermined intake air flow rate Q. When the intake air flow rate Q supplied through the throttle valve 4 suddenly decreases, the auxiliary air is gradually decreased and supplied through the auxiliary air passage 8b, and the air-fuel ratio of the air-fuel ratio due to the sudden decrease in the intake air flow rate Q is reduced. Avoid over-riching.

In step 3, the duty ratio ISCbcv is set. This duty ratio ISCbcv is set for deceleration suction negative pressure correction control for keeping the negative pressure in the intake manifold 5 constant during engine deceleration operation, and should be searched from a map corresponding to the engine speed N. Set by. Here, the duty ratio ISCbcv is the duty ratio IS.
Similar to the Cabv, it is set to be substantially constant above the predetermined engine speed N, but is set to be gradually decreased below the predetermined engine speed N, whereby the intake throttle valve 4 is set during engine deceleration operation. When is rapidly closed, a larger amount of auxiliary air is supplied in deceleration from a higher rotation, and an increase in intake negative pressure due to the closing of the intake throttle valve 4 is avoided.

In the next step 4, the feedback control value for making the actual rotation speed N closer to the target idle rotation speed and the basic characteristic value depending on the cooling water temperature when the engine 1 is in the idle operation (the idle switch 12 is ON). Including duty ratio
Set ISCdy.

Then, in step 5, the magnitudes of the various duty ratios set in steps 2 to 4 are compared, and the largest duty ratio (the duty ratio that opens the auxiliary air amount control valve 10 the most) is set as the final duty ratio ISCon. Then, in the next step 6, the drive pulse signal of the set duty ratio ISCon is output to the auxiliary air amount control valve 10, and the auxiliary air amount control valve 10 is adjusted to the opening degree according to the duty ratio ISCon.

By the way, in the present embodiment, even if the auxiliary air amount control valve 10 is fully opened, the auxiliary air amount is so small that the maximum auxiliary air amount required for the air-fuel ratio correction control or the suction negative pressure control cannot be secured. The control valve 10 is used. Therefore, during deceleration operation requiring a large amount of auxiliary air, the idle-up control valve that is normally controlled to open and close according to the external engine load (ON / OFF of the air conditioner) during idle operation regardless of the engine deceleration operation. Auxiliary air amount is corrected to be increased by auxiliary opening control of 9. Such control is performed according to the idle-up control valve open control routine shown in the flowchart of FIG. Therefore, in the present embodiment, the control unit 7 also serves as the forced open condition determination means and the idle-up control valve forced open control means.

First, in step 11, it is determined whether or not the engine 1 is in the decelerating operation state or immediately after the decelerating operation, based on the opening change of the intake throttle valve 4 detected by the opening sensor 11,
If it is determined that the vehicle is in deceleration operation, the next step
Go to 12. On the other hand, when the engine 1 is not in the deceleration operation state, the routine jumps to step 16 to control the idle-up control valve 16 to close. However, even when the routine proceeds from step 11 to step 16, when the engine 1 is in the idle operation state and the air conditioner relay 16 is still ON, the idle-up control valve 9 is controlled to be opened and the auxiliary air passage Auxiliary air is supplied through 8a.

In step 12, the duty ratio ISCabv for the air-fuel ratio correction control set in the flowchart of FIG. 3 described above is read.

Then, in the next step 13, the read duty ratio IS
It is determined whether Cabv is greater than or equal to a predetermined value, and the duty ratio
When the ISCabv is equal to or higher than the predetermined value and is in the deceleration operation state requiring a large amount of auxiliary air for the air-fuel ratio correction, the routine proceeds to step 14 and the idle up control valve 9 is opened (O
N) Yes. That is, in this routine, the auxiliary air amount control valve 10
The deceleration operation state, which is insufficient when the supplementary air amount is supplied only by the above, is determined based on the duty ratio ISCabv.

In step 15, the current duty ratio ISCabv and step
Compared with a predetermined value smaller than the predetermined value compared in 13,
Whether or not the duty ratio ISCabv is sufficiently reduced, in other words, the auxiliary air amount required only by the auxiliary air amount control valve 10 can be secured in the latter half of deceleration, and the auxiliary air is supplied via the idle-up control valve 9. It is determined whether there is no need.

Here, when the duty ratio ISCabv is large and the auxiliary air amount supply by the idle up control valve 9 is still required, the routine returns to step 14 to continue the open state of the idle up control valve 9, but the duty ratio ISCabv Becomes smaller and a large amount of auxiliary air is no longer required, the routine proceeds to step 16 where the idle-up control valve 9 is closed (OFF).

In this way, when a large amount of auxiliary air is required in the sudden deceleration operation state, the auxiliary air amount is not controlled only by the auxiliary air amount control valve 10, but the idle up control that is originally unrelated to the deceleration control. The auxiliary air amount is ensured by forcibly controlling the opening of the valve 9 to avoid over-riching of the air-fuel ratio and increase of the suction negative pressure during deceleration operation. Even if the capacity is relatively small,
It is possible to ensure good deceleration drivability. Also,
Auxiliary air amount control valve 10 whose duty is controlled as described above
With a small capacity, even if a failure occurs and abnormal control is performed to fully open, a large increase in rotation can be avoided.

As described above, the idle-up control valve 9 is used auxiliary as well as the duty-up control valve 9 based on the magnitude of the duty ratio ISCabv that determines the opening degree of the auxiliary air amount control valve 10 during the engine deceleration operation for the air-fuel ratio correction control. Instead of the ratio ISCabv, the opening / closing control of the idle-up control valve 9 may be performed by the duty ratio ISCbcv for the suction negative pressure control. Further, in the fuel injection control as well, since the reduction correction control for avoiding the enrichment of the air-fuel ratio during the deceleration operation is performed, the opening / closing control of the idle-up control valve 9 is performed based on the fuel reduction correction amount during the deceleration operation. It is also possible to do

Here, according to the routine shown in the flowchart of FIG. 5, opening / closing of the idle-up control valve 9 is performed by comparing a deceleration reduction correction coefficient KDC for reducing the fuel injection amount of the fuel injection valve 6 during engine deceleration operation with a predetermined value. The control for performing is described.

First, in step 21, it is determined whether or not the engine 1 is in the decelerating operation state. If it is in the decelerating operation state, the following step 22
Read the deceleration reduction correction coefficient KDC of the fuel injection amount set in another routine.

The deceleration reduction correction coefficient KDC is set according to the opening change rate of the intake throttle valve 4, the engine speed N, the cooling water temperature Tw, etc. when the deceleration operation state of the engine 1 is detected. ,
By correcting the steady-state fuel injection amount set according to the intake air flow rate by this deceleration reduction correction coefficient KDC,
It is intended to prevent enrichment of the air-fuel ratio due to the wall flow that is supplied late into the cylinder during deceleration operation. As described above, the deceleration reduction correction coefficient KDC is intended for the purpose of correcting the air-fuel ratio during deceleration.Therefore, the more the air-fuel ratio becomes richer, the larger the value is set and the more the amount of the correction is reduced. Therefore, the deceleration operation state that requires a large amount of auxiliary air can be determined by the magnitude of the deceleration reduction correction coefficient KDC.

Therefore, by comparing the read deceleration reduction correction coefficient KDC with a predetermined value in the next step 23, it is determined whether or not the operating state in which a large reduction correction is performed and a larger amount of auxiliary air is required, When the deceleration reduction correction coefficient KDC is equal to or greater than the predetermined value, the process proceeds to the next step 24, the idle up control valve 9 is opened (ON), and the auxiliary air amount control valve is opened.
The amount of auxiliary air supplied via the idle-up control valve 9 is added to the amount of auxiliary air supplied via 10 (see FIG. 6).

After the idle-up control valve 9 is controlled to be opened in step 24, the deceleration reduction correction amount is reduced by comparing the deceleration reduction correction coefficient KDC with a predetermined value which is the lower limit level in the next step 25. The operating state in which the required supply amount of the amount is reduced is determined.

Then, when the deceleration reduction correction coefficient KDC becomes sufficiently small and the fuel injection amount reduction correction becomes unnecessary,
Since the supply amount of the auxiliary air amount is small, the process proceeds to step 26 and the idle up control valve 9 is closed (see FIG. 6), and the auxiliary air amount control valve 10 alone is used. Try to control the amount.

<Effects of the Invention> As described above, according to the present invention, the auxiliary air amount for correcting and controlling the auxiliary air amount that is controlled by opening according to the deceleration operation condition and bypasses the intake throttle valve during deceleration operation. In an engine equipped with a control valve, in a decelerating operation state in which the required auxiliary air amount cannot be secured by the auxiliary air amount control valve, the idle is provided in parallel with the auxiliary air amount control valve to compensate for an increase in external load during idling. The up control valve is forcibly opened to ensure the required amount of auxiliary air and maintain good deceleration operability. Therefore, the amount of auxiliary air during deceleration operation needs to be secured by the total of the auxiliary air amount control valve and the idle-up control valve, and the capacity of the auxiliary air amount control valve can be made relatively small and fail It can be advantageous in terms of safety.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of the present invention, FIG. 2 is a system schematic diagram showing an embodiment of the present invention, and FIGS. 3 to 5 are flowcharts showing control contents in the same embodiment, respectively. The figure is a time chart showing the conventional problems and the control characteristics of the embodiment. 1 ... Engine, 4 ... Intake throttle valve, 7 ... Control unit, 8 ... Auxiliary air passage, 9 ... Idle-up control valve, 10 ... Auxiliary air amount control valve, 11 ... Opening sensor, 12
Idle switch, 13 Air flow meter, 14
... Rotation speed sensor

Claims (1)

[Scope of utility model registration request] 1. An idle-up control valve that is interposed in a first auxiliary air passage that bypasses the intake throttle valve and that opens and closes in an ON / OFF manner, and a bypass valve that bypasses the intake throttle valve and is in parallel with the first auxiliary air passage. An auxiliary air amount control valve, which is provided in a second auxiliary air passage provided and whose opening is controlled by a valve opening duty, and the idle-up control valve are opened / closed based on an on / off signal of an engine external load. An internal combustion engine comprising idle-up control means and valve opening duty setting means for setting the valve opening duty given to the auxiliary air amount control valve at least including the valve opening duty for deceleration according to the deceleration operation condition of the engine. In an auxiliary air amount control device for an engine, based on at least one of the valve opening duty for deceleration and a correction amount of a fuel supply amount determined according to deceleration operation conditions of the engine. The forced open condition determining means for determining the condition for forcibly opening the idle up control valve, and the forced open condition determining means for determining the condition for forcibly opening the idle up control valve. When
The idle up control valve is turned on / off of the engine external load.
An auxiliary air amount control device for an internal combustion engine, comprising: an idle-up control valve forced opening control means for forcibly opening control independently of an off signal.