JPH0826807B2 - Auxiliary air amount control device for internal combustion engine - Google Patents

Description

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

<Prior Art> Conventionally, as an auxiliary air amount control device for an internal combustion engine, an electromagnetic auxiliary air amount control valve is provided in an auxiliary air passage that bypasses a throttle valve provided in an engine intake system. The duty ratio of the drive pulse signal to the control valve (which is represented by the time ratio% of the pulse width to the cycle when controlling the opening by controlling the pulse width of the drive pulse signal for valve opening given in a constant cycle) It is known that the amount of auxiliary air is controlled by controlling the amount (see Japanese Patent Laid-Open No. 174549/1987).

Here, for the duty ratio DUTY (%) of the drive pulse signal to the auxiliary air amount control valve, the necessary auxiliary air amount Q (/ min) is calculated based on the engine operating conditions, and the auxiliary air amount Q is converted to Q- Set it by referring to the DUTY map.

That is, the maximum auxiliary air amount obtained when the duty ratio DUTY is 100% and the minimum auxiliary air amount obtained when the duty ratio DUTY is 0% are divided into substantially equal intervals,
Duty ratio DUTY corresponding to this divided grid of auxiliary air amount
Is provided (see FIG. 5), the Q-DUTY map is referenced based on the auxiliary air amount Q required for engine operating conditions, and the Q-DUTY map is used for the auxiliary air amount Q that does not match the grid position. Corresponding duty ratio calculated from interpolation
I was trying to get a duty. In addition, the reason why the divided grids of the auxiliary air amount are arranged at equal air amount intervals is to facilitate the interpolation calculation.

<Problems to be Solved by the Invention> By the way, in recent years, one auxiliary air passage having a large capacity is provided by collecting auxiliary air passages that have been individually provided for various purposes.
There is a device configured to control the amount of auxiliary air supplied through this large capacity auxiliary air passage to simplify the system and reduce costs accordingly. When the change in the air amount Q is constant, the auxiliary air amount rises more rapidly with respect to the duty ratio change than when controlling the small-capacity auxiliary air passage. Therefore, as shown in FIG. 5, the duty ratio DUTY The characteristics of the auxiliary air amount Q with respect to the above are laid down, and the change of the auxiliary air amount Q with respect to the change of the duty ratio is made dull except near the maximum duty ratio DUTY.

When the change characteristic of the auxiliary air amount Q is made to lie as described above, as shown in FIG. 5, the inflection point when the auxiliary air amount Q corresponding to the duty ratio DUTY is drawn on a plane curve. (The point where the plane curve changes from convex to concave with respect to a fixed straight line) occurs, but if the grid of the Q-DUTY map does not match this inflection point, the duty ratio DUTY between the grids including this inflection point There is a possibility that the accuracy of the interpolation calculation may deteriorate, and a drive pulse signal having a duty ratio different from the duty ratio DUTY at which the required auxiliary air amount Q is obtained is output, and the desired auxiliary air amount control cannot be performed.

That is, as shown in FIG. 5, when the grid of the Q-DUTY map is set with an inflection point as an intermediate value included in the grid,
Since the change in the auxiliary air amount Q with respect to the duty ratio DUTY is small in the vicinity of the inflection point, when the grids of the auxiliary air amount Q are set at equal intervals, the set width of the duty ratio DUTY between the grids including the inflection point is small. Is larger than the others, and the duty ratio DUTY change per unit auxiliary air amount is large, so the duty ratio corresponding to the required auxiliary air amount Q
It was difficult to calculate the DUTY with high accuracy.

The present invention has been made in view of the above problems, and in an auxiliary air amount control valve having a characteristic that an inflection point is generated when an auxiliary air amount Q corresponding to a duty ratio DUTY is drawn on a plane curve, The purpose is to prevent the setting accuracy of the duty ratio from decreasing near the inflection point.

<Means for Solving the Problems> Therefore, in the present invention, as shown in FIG. 1, an electromagnetic auxiliary air amount control valve is provided in an auxiliary air passage that bypasses the throttle valve interposed in the engine intake system, In the auxiliary air amount control device for the internal combustion engine configured to control the auxiliary air amount by controlling the duty ratio of the drive pulse signal to the auxiliary air amount control valve, the required auxiliary air amount is set based on the engine operating conditions. The auxiliary air amount calculating means for calculating and the inflection point when the auxiliary air amount corresponding to the duty ratio is drawn on a plane curve are offset in order to match the grid position for dividing the auxiliary air amount at equal intervals. Map storage means for storing a map in which the duty ratio is set corresponding to the grid of the auxiliary air amount, and the required auxiliary air amount calculated by the auxiliary air amount calculation means are set to the offset. And a duty ratio setting means for performing the interpolation calculation from the map stored in the map storage means based on the corrected required auxiliary air amount to set the duty ratio, and the duty ratio setting means. Drive pulse signal output means for outputting a drive pulse signal having a set duty ratio to the auxiliary air amount control valve.

<Operation> In this configuration, the map storing the duty ratio corresponding to the auxiliary air amount is such that the inflection point when the auxiliary air amount corresponding to the duty ratio is drawn on a plane curve is divided into equal intervals of the auxiliary air amount. The duty ratio is set corresponding to the grid of the offset auxiliary air amount to match the grid position to be corrected, and the required auxiliary air amount calculated by the auxiliary air amount calculating means is corrected based on the offset amount. Then, the duty ratio corresponding to the corrected auxiliary air amount is obtained by the duty ratio setting means performing interpolation calculation from the map,
The drive pulse signal of the set duty ratio is output to the auxiliary air amount control valve by the drive pulse signal output means,
The auxiliary air amount control valve is controlled to an opening degree according to the duty ratio.

As described above, if the map storing the duty ratio corresponding to the auxiliary air amount is set so that the grid intervals of the auxiliary air amount are equal and the inflection points are matched with the grid positions, the duty ratio can be set. The accuracy can be improved.

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

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. Quantity control valve 5
It is inhaled by the engine under the control of. 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.

The auxiliary air amount control valve 5 includes a control unit 9
The opening is controlled by the duty ratio DUTY of the drive pulse signal output from (the time ratio% of the drive pulse signal for valve opening), and for such control, signals from various sensors are input to the control unit 9. . Since the auxiliary air passage 4 has a relatively large capacity, the duty ratio DU
The change characteristic of the auxiliary air amount Q with respect to the duty ratio DUTY is made to lie in order to make the change of the auxiliary air amount Q with respect to the TY change (see FIG. 4).
An inflection point is generated when the auxiliary air amount Q corresponding to TY is drawn on a plane curve.

As the various sensors, a rotation speed sensor 10 is provided to detect the engine rotation speed N. In addition, the throttle valve 3 is provided with a potentiometer-type throttle sensor 11,
Detect the throttle valve opening TVO. In addition, the water temperature sensor 12
Is provided to detect the engine cooling water temperature Tw. In addition, the battery voltage VB is input.

Here, the microcomputer in the control unit 9 calculates the duty ratio DUTY of the drive pulse signal to the auxiliary air amount control valve 5 according to the flow chart of FIG. The drive pulse signal of DUTY is output to control the opening degree of the auxiliary air amount control valve 5.

 Next, description will be given along the flowchart of FIG.

In step 1 (denoted as S1 in the figure. The same applies hereinafter), engine speed N, throttle valve opening TVO, engine cooling water temperature
Read Tw, battery voltage VB, etc.

In Step 2, the engine speed N read in Step 1,
An auxiliary air amount Q (/ min) as a required auxiliary air amount required is calculated based on engine operating conditions such as throttle valve opening TVO and engine cooling water temperature Tw.

In step 3, the auxiliary air amount Q calculated in step 2
The offset amount ΔQ is added to the final auxiliary air amount Q
Set.

Then, in the next step 4, the duty ratio DUTY corresponding to the auxiliary air amount Q set in step 3 is obtained by interpolation calculation from the Q-DUTY map shown in FIG.

In the Q-DUTY map shown in FIG. 4, the inflection point when the auxiliary air amount Q actually obtained with respect to the duty ratio DUTY is drawn on a plane curve is one of the grids, and the equal air is drawn from the inflection point. A grid is set in the amount interval, and a portion where the grid cannot be set in the equal interval near zero of the auxiliary air amount Q is set as the offset amount ΔQ. This is because if the grids are set with the intervals of the auxiliary air amount Q set at equal intervals, the interpolation calculation can be easily performed. In reality, a predetermined duty ratio DUTY is required to obtain the offset amount ΔQ. By setting the duty ratio DUTY corresponding to this offset amount ΔQ to 0%, the ΔQ amount is offset, and the offset amount ΔQ is added to the required auxiliary air amount Q, and the map is referred to. The duty ratio DUTY can be calculated by interpolation on the map.

Further, as described above, if the inflection point is one of the grids, the width of the duty ratio DUTY corresponding to each of the grids of the auxiliary air amount Q provided at equal intervals becomes extremely large near the inflection point. It is possible to set the duty ratio DUTY with which the required auxiliary air amount Q can be obtained while maintaining the accuracy of the interpolation calculation. If the inflection point is set not to be one of the grids but to be sandwiched between the grids as shown in FIG. 5, the change of the auxiliary air amount Q with respect to the duty ratio DUTY is reduced near the inflection point. For this reason, the width of the duty ratio DUTY corresponding to the grid of the auxiliary air amount Q with the inflection point positioned in the middle becomes significantly larger than the others, and it becomes difficult to set the duty ratio DUTY with high accuracy. is there.

When the duty ratio DUTY corresponding to the required auxiliary air amount Q is set in step 4, the drive pulse signal of this duty ratio DUTY is output to the auxiliary air amount control valve 5 in step 5 to output the auxiliary air amount. The opening of the control valve 5 is controlled so that the required amount of auxiliary air Q can be obtained.

<Effects of the Invention> As described above, according to the present invention, in the auxiliary air amount control valve having a characteristic that an inflection point occurs when the auxiliary air amount corresponding to the duty ratio is drawn on a plane curve, In order to match the inflection point with the grid position that divides the auxiliary air amount into equal intervals, a map is provided in which the duty ratio is set corresponding to the offset auxiliary air amount grid, and the required auxiliary air amount is set to the offset amount. Since the duty ratio is set by referring to the map based on the value corrected based on the above, the duty ratio setting accuracy does not decrease in the vicinity of the inflection point, and the duty ratio of substantially the same accuracy is obtained in the entire amount range. The effect is that settings can be made.

[Brief description of drawings]

FIG. 1 is a block diagram showing the structure of the present invention, FIG. 2 is a system schematic diagram showing an embodiment of the present invention, and FIG. 3 is a flow chart showing a control routine of an auxiliary air amount control valve in the embodiment. Fig. 4 shows the amount of auxiliary air in the above embodiment
FIG. 5 is a graph showing a duty ratio map, and FIG. 5 is a graph showing a conventional auxiliary air amount-duty ratio map. 3 ... Throttle valve, 4 ... Auxiliary air passage 5 ... Auxiliary air amount control valve, 9 ... Control unit

Claims (1)

[Claims] 1. An electromagnetic auxiliary air amount control valve is provided in an auxiliary air passage that bypasses a throttle valve provided in an engine intake system, and a duty ratio of a drive pulse signal to the auxiliary air amount control valve is controlled. In an auxiliary air amount control device for an internal combustion engine configured to control the auxiliary air amount by means of the above, an auxiliary air amount calculation means for calculating a required auxiliary air amount based on engine operating conditions, and an auxiliary air amount corresponding to the duty ratio. Stores a map in which the duty ratio is set corresponding to the grid of the offset auxiliary air amount so that the inflection point when the amount is drawn on a plane curve matches the grid position that divides the auxiliary air amount at equal intervals. The map storage means, and the required auxiliary air amount calculated by the auxiliary air amount calculating means is corrected based on the offset amount, and based on the corrected required auxiliary air amount. The duty ratio setting means for performing the interpolation calculation from the map stored in the map storage means to set the duty ratio, and the drive pulse signal of the duty ratio set by the duty ratio setting means is output to the auxiliary air amount control valve. An auxiliary air amount control device for an internal combustion engine, comprising: