JPS601520A - Computing method of amount of intake air - Google Patents

Abstract

PURPOSE:To obtain the accurate amount of intake air, by detecting the maximum value and the minimum value of the detected amount of the intake air during a period exceeding the pulsating period of the detected amount of the intake air of an air flowmeter. CONSTITUTION:The pulsation of an amount Q' of detected intake air of an air flowmeter (a) when a throttle valve is fully opened (WOT) is shown, e.g., by the Figure. Namely, the pulsating period of this 4-cylinder engine is 180 deg. CA (CA: crank angle). Q' is pulsated between the maximum value Qmax and the minmum value Qmin in each pulsating period. Depending on the detected time, the amount Q' of the detected intake air is largely deviated up and down from the actual value. At this time, (Qmax+Qmin)/2 is made to be the amount of intake air Q. Based on the amount of intake air Q obtained in this way, a fuel injection time is computed, and air-fuel ratio controlling accuracy is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an intake air amount calculation method for calculating the intake air amount of an engine using an air flow meter.

The air flow meter is installed in the intake passage of the engine to detect the intake air L1, and the fuel angle injection amount is calculated based on this intake air amount. However, the output of the air flow meter pulsates due to intake pulsation, and this This causes deterioration of fuel ratio control accuracy.

Therefore, in general electronically controlled engines, the intake air amount Q' detected by the air flow meter is rounded, and for example, the intake air amount Q used as the basis for calculating the previous fuel injection amount and the current detected intake air amount Q'
The influence of pulsation is reduced by setting the intake air amount Q to the average value (Q+Q')/2. However, when the throttle valve approaches full opening, the output pulsation of the airflow meter increases, causing the detected intake air ff1Q' to deviate significantly from the actual value, and there are reports that the smoothed value also deviates from the actual value. . This problem is caused by high-response airflow such as Karman vortex airflow meters.

- It is noticeable in the ta.

An object of the present invention is to provide an intake air amount subtraction method that allows an accurate intake air amount to be calculated despite pulsations in the output of an air flow meter.

In order to achieve this objective, according to the intake air claw calculation method of the present invention, an air flow meter is provided in the intake passage of the engine,
The maximum value Qmax and minimum value Qmin of the detected intake air mQ during a period longer than the pulsation period of the detected intake air amount Q' of the air flow meter are detected, and the average value (Qmax 100 m
in)/2 is the intake air amount Q.

Since the detected intake air ifQ oscillates up and down with the same amplitude around the actual intake air amount, the average value of the maximum value Qmax and the minimum value Qmin (Qmax 10min)/2
is approximately equal to the true intake air amount. Therefore (Qm
By setting ax+Qmin)/2 as the intake air ff1Q, an accurate intake air amount can be determined even if the pulsation of the detected intake air amount Q' increases.

The present invention particularly exhibits a immersion effect at high loads in high-response airflow meters such as the Karman 11M type.

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

Figures 1 and 2 show Karman vortex air flow meter 1.
The pipe main body 2 forms an intake passage 4 and is provided between the air cleaner and the throttle valve. The intake air is rectified by first-stage and second-stage rectifier gratings 6 and 8. The local generator 10 is provided at the center of the intake passage 4, and the rectified intake air passes on both sides of the vortex generator 1o. Air pressure on both sides of the vortex generator 10 is guided to both sides in the width direction of the span band I4 via the pressure guiding holes 12a+I2b. The span band 14 is fixed at one end and is suppressed by a spring 18 via a suppressor 16 at the other end. The span band I4 connects the mirror 20 at a position corresponding to the upper end of the pressure holes 12a, 12b, and
Twisted in relation to the air pressure difference of 12h. The light from the light-emitting diode 22 may or may not reach the phototransistor 24 in relation to the oscillation of the mirror 20, so the phototransistor 24 is turned on and off in relation to the Karman spirit, and the light generated accordingly. By measuring the frequency of the pulse, it is possible to detect the Kalman flow (■ intake air flow rate).

FIG. 3 shows the pulsation of the intake air 1'4kQ' detected by the air flow meter 1 when the throttle valve is fully open (WOT). Note that this engine is a 4-kilometer engine, and the pulsation period is 180° CA (CA: crank angle). Q' pulsates between the maximum value Qmax and the minimum value Qmin in each pulsation cycle, and depending on the detection time, the detected intake air ffi
Q' deviates significantly above and below from the actual value. In the present invention (
Noting that Qmax + Qmin)/2 is a value extremely close to the actual amount of intake air, (Qmax 10 min)/2 is set as the intake air ff1Q. By calculating the fuel injection time based on the intake air amount Q thus determined, the air-fuel ratio control accuracy is improved.

FIG. 4 is a flowchart of a routine for detecting the maximum and minimum values of the detected intake air amount Q'.

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 detected intake air amount Q' from the occurrence period T of no output cover of air flow meter 1, and calculate the maximum value Q7nax and minimum value Qm of Q'.
Detect in. Since Qmax and Qmin are set to initial values in step 5o of FIG. 5, which is executed every time the crank angle changes by 180°, Qmax, 0
m1n is the maximum value and the lowest value of Q' in one pulsation period of Q'. To explain each step in detail, in step 30, the time interval I from the time of occurrence of the output rN+rus of the air flow meter to the time of occurrence of this time is detected as the period of the output pulse. In step 32, the detected intake air ffl q/ is set to 1 (substitute .-). However, K is a constant, and the detected intake air amount Q' is proportional to the frequency of the output pulse. In step 34, Q' and Qmax are If Q'≧Qmax, Q' is substituted for Qmax in step 36, and Q'<Qrna
If x, update of Qmax is canceled. In step 38, Q' and Qmin are compared, and if Q'≦Qm1n, Q' is substituted for Qmin in step 40, and Q'>
If it is Qmin, update of Qmin is canceled.

FIG. 5 is a flowchart of the intake air fXk calculation and fuel BUE 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 intake air fiQ
(Q+cax + Qmin)/2 is substituted for , and fuel injection is performed by dividing the fuel injection time rp based on Q after the crank angle has elapsed by 360°.

Each step will be described in detail. In step 46, it is determined whether 180 degrees of crank angle has elapsed. If the determination is positive, the process proceeds to step 52 via steps 48 and 50. If h1 is negative, the process proceeds directly to step 52. In step 48, <
Substitute Qmax +Qmrn)/2 for Q. In step 50, QmaX+Qmin is set to P)JQ!
Substitute il'f. The initial value of QIIlaX is O, and the first value of Qmin is a sufficiently large number L (for example, the value obtained by subtracting 1 from the complement of O). In step 52, it is determined whether 360" has elapsed in terms of crank angle. If the determination is positive, the process proceeds to step 54, and if it is apricot, this routine is ended. In step 54, the fuel injection time Tp is
/N function f (Q/N). However, N
is the actual rotational speed. In step 56, fuel injection from the fuel injection valve is executed.

[Brief explanation of the drawing]

Figure 1 is a longitudinal cross-sectional view of the Karman vortex air flow meter, Figure 2 is a cross-sectional view taken along the line ■-■ in Figure 1, Figure 3 is a graph showing the pulsation of the intake air amount detected by the air flow meter, FIG. 4 is a flowchart of the maximum value and minimum value detection routine of the detected intake air amount, and FIG. 5 is a flowchart of the intake air amount and fuel injection routine. ■... Air flow meter, 4... Intake passage, 20...
... Mirror, 22 ... Light emitting diode, 24 ... Photo h
transistor. Patent Applicant: Toyota Motor Corporation, ·····················································− figure

Claims (1)

[Scope of Claims] 1. An air flow meter is provided in the intake passage of the engine, and the maximum value Qmax and minimum value Qmjn of the detected intake air amount Q' during a period longer than the pulsation period of the detected intake air amount Q' of the air flow meter are detected. , average value (Qmax + Qmi
A method for calculating an amount of intake air, characterized in that the amount of intake air jfiQ is set as n)/2. 2. The method according to claim 1, wherein the air flow meter is a Kalman type air flow meter.