JPS63275914A - Measuring apparatus of flow rate of suction air of internal combustion engine - Google Patents

Abstract

PURPOSE:To conduct self-diagnosis of the lowering of precision of detection and to enable the implementation of correction based on the real condition, by correcting a measured quantity on the basis of a deviation from the quantity of sucked air at the time of arrival at a measuring point, parameters of which are a speed of rotation of an engine and an opening of a throttle valve and which is stored beforehand. CONSTITUTION:A detected value from a suction air flow rate detecting means interposed in an intake passage of an engine and comprising a hot-wire sensitive resistor is supplied to a suction air deviation value computing and storing means. From the outputs of an engine rotation speed detecting means and a throttle valve opening detecting means, simultaneously, a measuring and operating states discriminating means determines that the state of operation arrives at a measuring point, and a suction air quantity retrieving means reads a corresponding quantity of suction air from a suction air quantity storing means and supplies same to the suction air deviation value computing and storing means, which computes and stores the deviation of suction air resulting from the self-diagnosis of the lowering of precision. Based on the stored content, a measured value is corrected on the basis of the real condition by a suction air quantity correction formula setting means and a suction air quantity correcting means.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to an intake air flow rate measuring device for an internal combustion engine, and particularly to one including a temperature-sensitive resistor interposed in the intake passage of the engine. .

<Prior art> In a conventional electronically controlled fuel injection type internal combustion engine, a hot wire flow meter (Utility Model No. 60-152928 Based on the electrical signal (voltage) output corresponding to the intake air flow ff1Q of the engine from
Calculate the basic fuel injection amount Tp (←KXQ/N; is a constant) from this intake airflow IQ and the engine rotational speed N detected by a crank angle sensor, etc. This basic fuel injection amount Tp and cooling water temperature Tw
The final fuel injection amount Ti is calculated by making corrections according to the engine operating state, and an injection pulse signal corresponding to this fuel injection amount Ti is output to the electromagnetic fuel injection valve to inject fuel into the engine. It is injected and supplied intermittently.

<Problems to be Solved by the Invention> By the way, in the above-mentioned hot-wire type flowmeter, a temperature-sensitive resistor (hot wire) installed in the intake passage of the engine is cooled by the intake air when the intake air flow rate increases. Since the resistance value decreases, the output electric signal (voltage) changes accordingly, thereby detecting the intake air flow ff1Q of the engine.

Therefore, if dust, oil components, etc. adhere to the temperature-sensitive resistor (hot wire), this adhered substance acts to suppress the temperature drop of the temperature-sensitive resistor, so the temperature (resistance value) change characteristics with respect to the intake air flow rate Q changes, and as shown in FIG. 5, an amount smaller than the actual intake air flow ff1Q is output as a detected value. For this reason, when the engine is stopped, a large current is supplied to the temperature-sensitive resistor to heat it and burn off the deposits (see Utility Model Application Publication No. 61-52228, etc.). If the temperature-sensitive resistor deteriorates or if the deposits cannot be burnt off properly and remain, the hot wire flowmeter will detect an amount smaller than the actual intake airflow IQ as described above. In order to output the fuel, the basic fuel injection amount Tp is set to be smaller than the amount required by the engine, and the air-fuel ratio of the intake air-fuel mixture becomes lean, which impairs the drivability of the engine.

The present invention has been made in view of the above-mentioned problems, and provides an intake air flow rate measuring device that can self-diagnose the decrease in detection accuracy of a hot wire flowmeter and correct the detection value to a value corresponding to the actual intake air flow rate. The purpose is to

<Means for Solving the Problems> Therefore, in the invention, as shown in FIG. A flow rate detection means, an engine rotation speed detection means for detecting the engine rotation speed, a throttle valve opening detection means for detecting the opening of a throttle valve interposed in the intake passage, and a throttle valve opening detection means for detecting the throttle valve opening and the engine rotation speed. The measurement point operating state is determined based on the intake air flow rate storage means that stores the intake air flow rate in the operating state of a plurality of measurement points set as parameters, and the engine rotation speed and throttle valve opening detected by the detection means, respectively. and a measurement point operating state discriminating means for discriminating the measurement point operating state, and when the measuring point operating state discriminating means determines that the predetermined measurement point operating state is present, the intake air in the corresponding measuring point operating state is stored from the intake air flow rate storage means. An intake air flow rate search means for searching the flow rate, and an intake air for calculating and storing the deviation amount between the intake air flow rate searched by the intake air flow rate search means and the intake air flow rate detected by the intake air flow rate detection means. Deviation amount calculation storage means, and intake air flow rate correction formula setting for setting a correction formula for the intake air flow rate based on the amount of deviation of the intake air flow rate in operating conditions at a plurality of measurement points stored in the intake air deviation amount calculation storage means. and an intake air flow rate correction means for correcting the intake air flow rate detected by the intake air flow rate detection means based on a set intake air flow rate correction formula.

According to this intake air flow measuring device, it is determined based on the detected values of the engine rotation speed and the throttle valve opening that the measurement point operating state is set using the engine rotation speed and the throttle valve opening as parameters. Then, the amount of deviation between the intake air flow rate stored in advance corresponding to the operating state at that measurement point and the intake air flow rate detected by the intake air flow rate detection means that includes a temperature-sensitive resistor. is calculated and the calculation result is stored. Then, when the deviation amounts are calculated and stored in the operating states of a plurality of measurement points, a correction formula for the intake air flow rate is set based on the correlation of the operating states of the measurement points and the deviation amounts. and,
The intake air flow rate detected by the intake air flow rate detection means is corrected using this intake air flow rate correction formula to obtain the final intake air flow rate.

(Example> An embodiment of the present invention will be described below based on the drawings.

FIG. 2 shows a system outline of an electronically controlled fuel injection type internal combustion engine equipped with an intake air flow rate measuring device according to the present invention.

Throttle valve installed in the engine intake passage (not shown)
The throttle valve opening signal α output from the throttle valve opening sensor 1 as a throttle valve opening detection means for detecting the opening α of the throttle valve, engine rotational speed detection means for detecting the output voltage Vs output from the hot wire flow meter 2 as an intake air flow rate detection means including a temperature resistor) corresponding to the intake air flow rate Q, and the engine rotational speed N; A water temperature sensor 4 detects the engine rotation speed signal N outputted from the rotation speed sensor 3 as the engine, and the temperature Tw of the cooling water in the engine cooling jacket.
A cooling water temperature signal TW outputted from the cooling water temperature signal TW is inputted to a control unit 5 having a built-in microcomputer.

The control unit 5 corrects the detected value of the intake air flow rate Q based on these signals, sets the fuel injection amount Ti, and sends an injection pulse signal corresponding to the fuel injection amount iTi to the electromagnetic fuel injection valve 7. Output to the drive circuit 6.

That is, in this embodiment, the control unit 5:
It also functions as a measurement point operating state determination means, an intake air flow rate search means, an intake air flow rate storage means, an intake air deviation amount calculation storage means, an intake air flow rate correction formula setting means, and an intake air flow rate correction means.

Next, the intake air flow fi detected by the control unit 5
The correction formula setting of iQ and the setting control of the fuel injection amount Ti based on the corrected intake air flow rate Q will be explained based on the flowcharts of FIGS. 3 and 4.

The flowchart in FIG. 3 shows a correction formula setting routine for setting a correction formula for correcting the intake air flow rate Q detected by the hot wire flow meter 2.

Step (shown as S in the figure, the same applies below) 1
Now, the throttle valve opening α detected by the throttle valve opening sensor 1, the output voltage Vs of the hot wire flowmeter, and the engine rotational speed N detected by the rotational speed sensor 3 are input.

In step 2, it is determined whether the current driving state is the first measurement point driving state.

This first measurement point driving condition u (#1) and the second measurement point which will be described later. The third measurement point operating state (#2° #3) indicates an operating state in which the intake air flow rate Q is different, as shown in FIG. 5, and is the intake air flow rate Q in the first measurement point operating state.

is the smallest, and the intake air flow rate Q in the operating state at the third measurement point is the largest.

The operating status of these measurement points is the throttle valve opening α
and the engine rotational speed N. That is, when the intake air flow rate Q in the measurement point operating state is set, the operating state in which this intake air flow rate Q is obtained is divided by the throttle valve opening α and the engine rotational speed N, and the actually detected throttle valve opening α is determined. It is determined whether or not the engine rotational speed N indicates an operating state in which the intake air flow rate Q is obtained in the operating state at the measurement point.

When it is determined in step 2 that the current operating state is the first measurement point operating state, that is, the throttle valve opening α
When the engine rotational speed N indicates an operating state in which the intake air flow rate Q is obtained, the process advances to step 3, and as shown in FIG. 5, the voltage output from the hot wire flow meter 2 is The deviation ΔV between Vs, (corresponds to the intake air flow rate Q1 and is stored in advance) and the current output voltage Vs from the hot wire flowmeter 2 input in step 1.
s, is calculated and stored. The larger this deviation ΔVsl is, the more the detection accuracy of the hot wire flowmeter 2 is reduced due to dirt on the hot wire and the like.

On the other hand, when it is determined in step 2 that the current driving state is not the first measurement point driving state, the process proceeds to step 4 and it is determined in the same way as step 2 whether or not the current driving state is the second measurement point driving state.

Here, if it is determined that the current operating state is the second measurement point operating state, the process proceeds to step 5, and similarly to step 3, in the second measurement point operating state, in the initial state where the hot wire is not contaminated, Calculate the deviation ΔVs2 between the voltage Vs output from the flowmeter 2 (corresponding to the intake air flow rate Q2 and stored in advance) and the current output voltage Vs from the hot wire flowmeter 2 input in step 1. Remember.

If it is determined in step 4 that the operating state is not at the second measurement point, the process proceeds to step 6 to determine whether the current operating state (throttle valve opening α and engine rotational speed N) is in the operating state at the third measurement point. The determination is made in the same manner as in step 2.4 above.

Here, when it is determined that it is the third measurement point operating state, the process advances to step 7, and in the third measurement point operating state, the voltage Vss ( The deviation ΔVs= between the current output voltage Vs from the hot wire flowmeter 2 inputted in step 1 is calculated and stored.

On the other hand, when it is determined in step 6 that the current operating state is not the third measurement point operating state, that is, the current operating state is the first. If it does not correspond to either the second or third measurement point operating state, this routine is ended as is.

After the deviations ΔVs, ~ΔVS3 (this amount of deviation increases as the hot wire in the hot wire flowmeter 2 becomes dirty) are calculated in steps 3 and 5.7, respective corrections are made in steps 8 and 9. Output voltage Vs in zone
Set the correction formula for

In step 8, between the first measurement point operating state and the second measurement point operating state (the intake air flow rate Q is Q, and Qz
The correction formula in the first correction zone (which is between

Vs←Vs+ΔVs, +((ΔVsg−ΔVs+)/(
Vs*-Vs+) ) X ((Vs-Vs
+y)/(Vsty Vs+y)) Here, Vs+y and Vszy are each the first
゜Difference ΔV s r in the second measurement point operating state
*This is the output voltage Vs of the hot wire flowmeter 2 used to calculate ΔVsx, and is stored when the deviations ΔVs+ and ΔVs2 were calculated in step 3 or step 5.

On the other hand, in step 9, it is determined that the intake air flow rate Q between the second measurement point operating state and the third measurement point operating state is Q2.
and Q3) is set according to the following formula.

VS4-VS+ΔVs2+ ((ΔVs3-ΔVSZ)
/(Vs3Vsz) )
y)/(V s, y V 5zy) ) Here, V s, y is the deviation ΔVs3 in the third measurement point operating state, similar to V s + y and Vszy.
This is the output voltage Vs of the hot wire flowmeter 2 used to calculate , and was stored when the deviation ΔVs3 was calculated in step 7.

The above correction formula is for raising the output voltage Vs, which decreases when the hot wire of the hot wire flowmeter 2 becomes dirty, to the initial value as shown in FIG. Assuming that the deviation amount increases and decreases linearly, the output voltage Vs is corrected to increase by estimating the deviation amount between the measurement point operating states based on the deviation ΔVs, .about.ΔVs= in the measurement point operating state. Therefore, the fifth
As shown in the figure, a correction formula may be set to correspond to the output voltage Vs which actually changes in a curved manner with respect to the intake air flow rate Q.

The correction formula for the intake air flow rate Q set in this way is:
It is used in the fuel injection amount setting routine shown in the flowchart of FIG.

In step 11, the throttle valve opening α detected by the throttle valve opening sensor 1, the output voltage Vs of the hot wire flowmeter 2, the engine rotation speed N detected by the rotation speed sensor 3, and further detected by the water temperature sensor 4 are processed. Enter the coolant temperature Tw.

In step 12, the output voltage S of the hot wire flowmeter 2 inputted in step 11 is converted into an intake air flow rate Q.

In step 13, a correction zone is determined based on the intake air flow ftQ converted in step 12. Here, if it is determined that it is in the first correction zone (Q+ <Q<Qz), the process proceeds to step 14, and step 1 is performed based on the correction formula set in step 8 of the flowchart of FIG.
A correction calculation is performed on the output voltage Vs inputted in step 1, and the output voltage s, which has decreased due to the contamination of the hot wire, is increased to the initial state output voltage Vs.

Also, in step 13, the second correction zone ((h<Q
), the process proceeds to step 15, and similarly to step 14, the output voltage Vs inputted in step 11 is corrected based on the correction formula set in step 9 of the flowchart of FIG.

On the other hand, if the operating state is outside the correction zone, step 13
If it is determined in step 17, the process jumps to step 17 without performing any correction based on the correction formula.

When a correction calculation based on the correction formula for the output voltage Vs is performed in step 14 or step 15, the corrected output voltage Vs is converted into an intake air flow ilQ in step 16. That is, the intake air flow rate Q converted in step 16 is a value that has been corrected for a decrease in detection accuracy due to contamination of the hot wire of the hot wire flowmeter 2, and is close to the actual value.

In step 17, step 12 or step 16
The basic fuel injection amount Tp (←KXQ/N; is a constant) is calculated based on the intake air flow rate Q obtained by converting the output voltage Vs in step 11 and the engine rotational speed N input in step 11.

In step 18, various correction coefficients C0EF are set based on the cooling water temperature Tw and throttle valve opening α (indicating idle state or acceleration state) input in step 11, and the effective valve opening time of the fuel injection valve 7 is determined based on the battery voltage. A voltage correction numerator s is set to correct the change in .

In step 19, the basic fuel injection amount Tp calculated in step 17 is adjusted to the various correction coefficients C0 set in step 18.
The final fuel injection 1lTi (←TpXCOEF+Ts) is set by performing a correction calculation using EF and the voltage correction numerator s.

In step 20, a predetermined amount of fuel is injected and supplied to the engine by outputting an injection pulse signal corresponding to the set fuel injection amount Ti to the drive circuit 6 of the fuel injection valve 7 at a predetermined timing.

In this embodiment, the correction formula for the intake air flow rate Q was derived by using three measurement points in the operating state.
It is clear that by increasing the number of measurement point operating states, it is possible to perform correction that more closely approximates the actual value.

<Effects of the Invention> As explained above, according to the present invention, the decrease in the detection accuracy of intake air flow rate due to dirt on the temperature sensitive resistor (hot wire) can be reduced by comparing the initial intake air flow rate and the detected value in the operating state of multiple measurement points. Self-diagnosis is performed based on the deviation, and the detected value is corrected based on the correction formula set based on the diagnosis result, so even if the temperature-sensitive resistor becomes dirty, the inhalation value approximates the actual value. This has the effect of making it possible to detect the air flow rate.

[Brief explanation of the drawing]

Fig. 1 is a configuration diagram of the present invention, Fig. 2 is a system block diagram showing an embodiment of the present invention, Fig. 3 is a flowchart showing a correction formula setting routine in the above embodiment, and Fig. 4 is a flowchart in the above embodiment. A flowchart showing the fuel injection amount setting routine, and FIG. 5 is a graph showing the relationship between the output voltage of the hot wire flow meter and the intake air flow rate. Engineering...Throttle valve opening sensor 2...Hot wire flowmeter 3...Rotation speed sensor 5...Control unit Patent applicant Japan Electronics Co., Ltd. Patent attorney Fujio SasashimaFigure 1 Figures 3 and 4 σ6 α-N Corresponding intake air flow 20

Claims (1)

[Claims] An intake air flow rate detection means for detecting the intake air flow rate of the engine, which includes a temperature-sensitive resistor inserted in the intake passage of the engine; an engine rotation speed detection means for detecting the engine rotation speed; Throttle valve opening detection means for detecting the opening of the installed throttle valve; and intake air flow rate memory that stores the intake air flow rate in operating conditions at multiple measurement points set using the throttle valve opening and engine rotational speed as parameters. a measurement point operating state determination means for determining the measurement point operating state based on the detected engine rotational speed and throttle valve opening; an intake air flow rate search means for searching the intake air flow rate at the corresponding measurement point operating state from the intake air flow rate storage means when it is determined that An intake air deviation amount calculation storage means that calculates and stores the deviation amount from the intake air flow rate detected by the air flow rate detection means, and a plurality of measurement points stored in the intake air deviation amount calculation storage means, an intake air flow rate correction formula setting means for setting a correction formula for the intake air flow rate based on the deviation amount of the air flow rate; and an intake air flow rate detected by the intake air flow rate detection means based on the set intake air flow rate correction formula. An intake air flow rate measuring device for an internal combustion engine, comprising: an intake air flow rate correction means for correcting.