JPS601521A - Computing method of amount of intake air - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an intake air amount calculation method that uses an air flow meter to subtract the amount of intake air between idlers.

The air flow meter is installed in the intake passage of the engine to detect the amount of intake air, and the amount of fuel injection is calculated based on this amount of intake air. This causes deterioration of air-fuel ratio control accuracy.

In order to prevent such problems, in conventional electronically controlled engines, the amount of intake air is calculated by rounding down the intake air R'CQ' detected by the air flow meter. Focusing on the fact that it is extremely similar, we have already disclosed in Separate Paper 1 the following subtraction method in addition to the calculation method of intake air amount by annealing.In other words, according to this calculation method of intake air amount, the intake passage of the engine An air flow meter is installed at
Let ax 10 min) / 2 be the intake air ff1Q. However, even in this method of calculating intake air Hk tl, when the throttle valve opening approaches full opening, the pulsation of the intake air Hk Q' detected by the air flow meter increases, and the average value (Qmax - 1 - Qmin) / 2 itself increases. deviates from the actual value and becomes a large value, making it impossible to carry out appropriate air-fuel ratio control.

An object of the present invention is to provide an intake air amount calculation method that can determine an appropriate intake air amount even near the throttle valve fully open (WOT).

In order to achieve this object, the present invention provides an average value (Qm
During the period in which ax 10min)/2 is greater than or equal to the limit value 08, the constant value Qc is set as the intake air fuQ.

Therefore, the pulsation of the intake air amount Q' detected by the air flow meter increases, and the average value (Qmax + QJI
The period during which Iin )/2 deviates from the actual value and becomes a large value is (Qmax + Qmjn )/2≧Qg
Since the constant value Qc, which is estimated to be extremely close to the actual value of the intake air amount during the detected period, is set as the intake air fTtQ, the intake air amount becomes the basis for dividing the fuel injection time, etc. Q can be set to an appropriate value even when the small valve is fully open.

The limit value Qg1 for determining whether the average value (Qmax 10 min)/2 is outside the actual value of the intake air amount and the average value (Qmax
The constant value Qc, which is determined as a value close to the actual value instead of x + Qmin) / 2, changes in relation to the engine rotation speed N, so the limit value Qg and the constant value Qc are a function of the engine rotation speed N. is preferable.

It is preferable that the constant value Qc be approximately the theoretical value of the amount of intake air when the throttle valve is fully open.

The present invention exhibits excellent effects particularly when applied to a high-response type air flow meter such as a Karman temperature type air flow meter.

The present invention will be described in detail with reference to the drawings.

In addition, in calculating the fuel injection time, the amount of intake air per revolution of the engine is the basis of the calculation, so in the example, the intake air fjl Q' detected by the air flow meter, the maximum value QIIlax and the minimum value Qmin 1 average value in the pulsation period are used. (Qmax 10min) / Limit value Qg1 as a guard of 2 and average value (Qmax 10Qmin) /
2 deviates from the actual value due to the pulsation of Q', instead of the constant value Qc that should be determined as the intake air amount Q, Qn' + as a value divided by the engine speed N.
This will be explained using Qnmax+ Qnmin+ Qng+ Qne.

1 and 2 show a Karman flow type air flow meter 1, in which a pipe main body 2 forms an intake passage 4 and is provided between an air cleaner and a throttle valve. The intake air is rectified by first-stage and second-stage rectifier gratings 6 and 8. The thermogenic body lO is provided at the center of the intake passage 4,
The rectified intake air passes on both sides of the vortex generator 10.

The air pressure on both sides of the vortex generator 10 is transmitted through pressure guiding holes 12a and 12b.
are guided to both sides of the span band 14 in the width direction. The span band 14 is fixed at one end and is pressed by a spring 18 via a suppressor 16 at the other end. The span band 14 has mirrors 20 at positions corresponding to the upper ends of the pressure holes 12a and 12b, and
, twisted in relation to an air pressure difference of +2b. The light from the light-emitting diode 22 is reflected by the oscillation of the mirror 20.
~Since it does not reach or go far from the transistor 24,
The phototransistor 24 is turned on in relation to the Karman vortex,
Karman vortex (intake air flow rate) can be detected by turning off the valve and measuring the frequency of the pulses that occur along with this.

FIG. 3 shows the temporal change in intake air mqn' per engine revolution calculated from the output of the air flow meter l. Qn' pulsates due to the pulsation of the detected intake air amount Q' detected from the output of the air flow meter l. Note that this engine is a 4-cylinder engine, and the pulsation period is 180° CA (C
A: crank angle). (Qnmax +Qnmi
Focusing on the fact that n)/2 is extremely close to the actual intake air amount, in a normal period, (Qnmax + Qn
Let 'min)/2 be Qn'. However, when the throttle valve is close to fully open, (Qnmax + Qnmi
n)/2 also deviates greatly from the actual value of the intake air amount, and (
The size of the document that defines Qn as Qnmax + Qnmin )/2 increases.

FIG. 4 shows the relationship between the intake pipe pressure and the intake air flIQn per engine revolution as a result of calculation. The average value (Qnmax + Qnmin) / 2 is close to the theoretical value (actual value) in the range where the throttle valve opening is small (= the range where the intake pipe pressure is low), but when the throttle valve is close to fully open, due to the pulsation of Qn' Can be increased from the actual value. In the example, the period during which (Qnmax + Qnmin) / 2 is less than Qng as a guard is (Qnrnax
+ Qnmin ) / 2 is Qn, but (Qn
In a period in which max 10 nm1n)/2 is equal to or greater than Qng, the constant value Qnc is set as the intake air ff1Qn.

The limit value Qng is (Qnmax + Qnmin) /
2 is set as a value to determine that it deviates greatly from the actual value due to the pulsating output of the air flow meter l, and is set to be a value that is slightly/11 smaller than the theoretical value when the throttle valve is fully open (WOT), for example. . The constant value Qnc is (Qn
The value is set as the actual value or a value close to it during a period in which max Qnmin)/2 deviates significantly from the actual value, and is, for example, the theoretical value at WOT.

FIG. 5 shows the relationship between the engine rotational speed N and the aforementioned limit value Qng and constant value Qnc. Qng and Qnc
is set as a function of N. The displacement of this engine is 2
000 cc.

FIG. 6 is a flowchart of a routine for calculating the maximum and minimum values of Qn'. This routine is an interrupt routine that is executed in response to the generation of an output pulse from the air flow meter 1. Determine the intake air ff1Qn' per engine rotation from the generation period T of the output pulse of the air flow meter 1, and calculate the maximum value QnmaX and the minimum value Qnmin of Qn'.
Detect.

Qnmax and Qnmin are set to initial values in step 50 of FIG. 7, which is executed every time the crank angle changes by 180°, so Qnmax, Qnllll
n is the maximum value and minimum value of Qn' in one pulsation period of Qn'. To explain each step in detail, in step 30, the time interval from the previous generation time of the output pulse of the air flow meter 1 to the current generation time is detected as the period T of the output pulse. In step 32, the intake air filQn' is set to the detected intake air ffi Q' as Qn' = Q
Calculated from the formula '/N. However, K is a constant and N is the engine rotation speed.

In step 34, Qn' and Qnmax are compared and Qn
'≧Q1max, in step 36 Qnmax
Substitute Q n/ for x, and if Qn'< Qnmax, update of Qnmax is stopped. In step 38, Q
n/ and Qnmin are compared, and if Qn'≦Qnmin, Qn' is substituted for Qnmin in step 40, and if Qn'>Qnmin, updating of Qnmin is stopped.

FIG. 7 is a flowchart of the intake air amount calculation and fuel injection routine. This routine is an interrupt routine that is executed every predetermined cycle of the crank angle, and every time the crank angle elapses by 180'', the average value (Qnmax
nmin ) / 2 is substituted into Qn, Qn and Qng are compared every time the crank angle elapses 360°, and Q
If n < Qng, Qn is not changed, that is, Qn
= (Qnmax+Qnmin)/2, Qn≧Q
If ng, Qnc is substituted for Qn. To explain each step in detail, in step 46, the crank angle is 180°.
It is determined whether or not the period has elapsed, and if the determination is positive, the process proceeds to step 52 via steps 48 and 50, and if not, the process directly proceeds to step 52. In step 48, (Qnu+ax
Substitute 100nm1n)/2 into Qn. step 50
Now, assign the initial value to Qnmax + Qnmin.

The initial value of Qnmax is 0, and the initial value of QnIIlln is a sufficiently large number L (for example, the value obtained by subtracting 1 from the complement of 0). In step 52, the crank angle is 360°
It is determined whether the period has elapsed, and if the determination is ■, step 54
If not, this routine ends. In step 54, the limit value Qng is set as a function f (N
). In step 56, the constant value Qnc is calculated as a function g(N) of the engine rotational speed N. In step 58, Qn and Qng are compared, and if Qn≧Qng, Qnc is substituted for Qn in step 60, and if Qn<Qng, Qn is not changed and the process proceeds to step 62. In step 62, the fuel injection time '1'p is calculated as a function h (Qn) of Qn.

In step 64, synchronous fuel injection is performed in the fuel injection valves.

[Brief explanation of the drawing]

Figure 1 is a longitudinal cross-sectional view of the air flow meter, Figure 2 is a cross-sectional view taken along the l-1 line in Figure 1, Figure 3 is a graph showing the pulsation of the intake air amount per engine revolution, and Figure 4. is a graph showing the relationship between intake pipe pressure and intake air amount per engine rotation as a result of 1+ calculation, Figure 5 is a graph showing the relationship between engine speed and limit value and constant value, Figure 6 is engine Maximum value and maximum d\value tl' of detected intake air amount per revolution
FIG. 7 is a flowchart of the intake air amount calculation and fuel lip injection routine. ■...Air flow meter, 4...Intake passage, IO・
...Vortex generator, 22...Light emitting diode, 24...
huo)-1-rangister. Agent Patent Attorney Nakahan γi: 1 layer, 1.1, ′・Yu, −1 Fig. 2 soil iヱ・times ■ Higashikuwa Q screw Onsara Higashi qQ Yong

Claims (1)

[Scope of Claims] l An air flow meter is provided in the intake passage of the engine, and the maximum value Qmax and minimum value Qmin of the detected intake air amount Q' are detected during a period longer than the pulsation period of the intake air i5k Q' detected by the air flow meter. In the intake air amount division method in which the average value (Qmax 10 min)/2 is the intake air ff1Q, the average value (Qmax + Qmin)
2 is above the limit value 08, a constant value Qc is set to intake air 11↓Q. 2. The method according to claim 1, characterized in that the limit value Qg and the constant value Qc are made functions of the engine rotational speed N. 3. The method according to claim 2, wherein the constant value Qc is approximately the theoretical value of the amount of intake air when the throttle valve is fully opened. 4. The method according to claim 3, wherein the air flow meter is a Karman vortex type air flow meter.