JPS6332144A - Air quantity detecting device for internal combustion engine - Google Patents

Abstract

PURPOSE:To enhance transient responsiveness by correcting the air flow rate at a steady state, which has been calculated by the opening of a throttle valve and the engine speed, by means of a delay factor corresponding to the operating condition, and adding a prescribed adding value to the air flow rate to a cylin der to detect the passing air quantity at a fuel injection part. CONSTITUTION:From a throttle valve opening alpha and an engine speed N, an air flow rate QH is accurately detected without being influenced by an intake pulsation. In addition, by adding a correction to this air flow rate QH by means of a delay factor K based on the throttle valve opening alpha and the engine speed N, the air flow rate Qc to a cylinder is accurately detected without worsening responsiveness even in the course of transient. And by adding a prescribed adding quantity CM (corresponding to the air flow rate Qc and the volume of the intake manifold) to the air flow rate QH, the passing air quantity at a fuel injection part can be accurately detected.

Description

[Detailed description of the invention] (Industrial application field) TECHNICAL FIELD This invention relates to an empty space detection device for an internal combustion engine.

(Prior art) In a fuel injection type internal combustion engine, it is important to accurately detect the amount of air taken into the engine. There are methods that detect it directly and methods that indirectly detect it from the intake pipe internal pressure and engine rotation speed measured by a pressure sensor. In addition to the pressure sensor, there is also a throttle valve opening sensor that detects the amount of air based on the throttle valve opening and the pressure in the intake pipe (see Japanese Patent Publication No. 61-4981, etc.).

(Problems to be Solved by the Invention) However, in the detection device using a flow rate sensor or a pressure sensor, the detected value fluctuates greatly due to intake pulsation, and the injection of the fuel injector is controlled based on this. Since the amount fluctuates, the torque fluctuation of Ennon becomes large.

Further, since the responsiveness of flow rate sensors and pressure sensors is not so good, there are problems in that detection errors during transient periods are large and costs are high.

On the other hand, since these detection devices detect the air flow rate at the sensor position, the detected value and the amount of air flowing into the cylinder may not match during transient periods, and depending on the position of the fuel injector, the fuel This does not match the amount of air passing through the injection section, which causes a problem in which the air-fuel ratio becomes rich or lean during acceleration or deceleration.

It is an object of the present invention to solve these problems and provide an air amount detection device with good transient response.

(Means for Solving the Problems) As shown in FIG. 1, the present invention includes a means 1 for detecting the opening of the throttle valve, a means 2 for detecting the engine rotational speed, and a means for detecting the steady state from both side output values. Steady air flow rate calculation means 3 for calculating the air flow rate; delay coefficient calculation means 4 for calculating the air flow delay coefficient from both side output values; and calculation means for calculating the air flow rate flowing into the cylinder from the steady air flow rate and the delay coefficient. a delay correction means 5 for calculating a predetermined addition amount from the calculation value of the delay correction means 5; and an addition amount calculation means 6 for calculating a predetermined addition amount from the calculation value of the delay correction means 5; and an air flow rate addition means 7 for calculating the flow rate of passing air.

(Function) Therefore, from the throttle valve opening a and the engine rotation speed N,
Airflow fiQ without being affected by intake pulsation
11 is accurately detected, and this air flow rate Ql+
Delay coefficient K based on throttle valve opening α and engine speed N
By applying the correction, the air flow rate Qc to the cylinder can be accurately detected without deteriorating the responsiveness even in the case of a transient r+. Then, by adding a predetermined addition amount ΔCM (corresponding to the air flow rate Qc and the volume of the intake manifold) to the air flow rate (Qll), the air flow rate passing through the fuel injection section can be accurately detected.

(Embodiment) FIG. 2 shows the present invention installed in the intake passage 11 upstream of the throttle valve 10.
This figure shows the mechanical construction of an embodiment applied to a single-point innoction type ennon equipped with two fuel injection valves 12.

14 is a throttle valve opening sensor that detects the opening degree α of the throttle valve 10, and 15 is a crank angle sensor that detects the engine rotation speed N. These detection signals are sent to a water temperature sensor 161 that detects the Ennon cooling water temperature, and a water temperature sensor 161 that detects the intake air temperature. An intake temperature sensor (not shown) that detects temperature, and an air-fuel ratio sensor 1 that detects air-fuel ratio
The signal is input to the control unit 18 along with the signals from 7 and the like.

Further, 19 is a passage that bypasses the throttle valve 10, and 20 is an idle control valve that makes the opening area A IJ of the bypass passage 19 variable.

The control unit 18 includes a CPU and a RAM.

It is composed of a microcomputer consisting of 1 (○M, I10 devices, etc.), has all the functions of each means 1 to 7 shown in FIG. The control unit 18 also drives and controls the idle control valve 2 ( ) so as to maintain a predetermined engine rotation speed during idle, for example.

Next, the contents executed in the control unit 18 will be explained based on charts 70 of FIGS. 3 to 5.

FIG. 3 shows a calculation routine for the air flow rate Qc flowing into the cylinder. First, in step 10, the throttle valve opening area Aα is determined from the signal a of the throttle valve opening sensor 14 by table search. FIG. 6 shows a characteristic diagram representing the contents of the table.The opening area Aa changes in proportion to the throttle valve opening a.

Step 11'c is the opening of the passage 19 that bypasses the throttle valve 10 from the table search 1 from the drive control number 4H (duty signal) ISCD which commands the idle control valve 20!
The area A IJ is calculated. FIG. 7 shows a characteristic diagram representing the contents of the table. The opening degree of the idle control valve 20 increases as the duty value increases, and the opening area Ab increases accordingly.

Then, in step 12, the total flow path area A is squeezed out from the sum of the throttle valve opening area Aα and the bypass passage opening area Ab.

Next, in step 13, the steady state air flow rate Ql+ for the total flow path area A is determined. /N and ;non rotation speed N!
: Obtained from the 3D table allocated to . 8th
The figure is a characteristic diagram showing the contents of the table.
t#il has a characteristic that increases approximately according to A/N. This is because, assuming that the rotational speed N is constant, the A/N changes depending on the throttle valve opening degree α, and the larger α becomes, the more the air flow rate increases.

In step 14, a delay coefficient K (K
<1) is determined from the total flow path area A and the engine rotational speed N by table search.

This search is performed using a three-dimensional table, and PtIJ9
The figure shows a characteristic diagram representing the contents of the table. Note that the delay coefficient changes approximately depending on the total flow path area A.

Then, in step 15, the air flow rate Qc to the cylinder is determined by the air flow rate Q11 and the delay coefficient, so that Q c=Q
It is calculated by the formula co + K (Q If Q co). Q eQ is the previously calculated air flow rate Qc, and in a steady state, Qc = Qtl.

FIG. 4 shows a routine for measuring the air flow if QlI passing through the intake passage 11 of the fuel injection valve 12. First, in step 20, the total 1 of FIG. The addition WfitΔCM is determined from the difference value ΔQc (=Qc−Qco) of the airflow mQc determined in the routine and the constant KN.

Difference value of air flow rate Q c Difference value ΔQ c Air flow rate Q c
The pressure inside the intake manifold 21 changes according to the increase or decrease in the amount of pressure, and the additional amount ΔCM is calculated by multiplying the volume of the intake manifold 21 by the amount of air that changes the pressure by a constant KN that has a strong correlation with the volume of the intake manifold 21.

Then, in step 21, the exposure amount ΔCM is added to the air flow m Q II, and the air flow rate QalJtf'l is output.

The air flow rate Qa passing through the fuel injection section is calculated backward based on the increase/decrease in the air flow rate Qll and the air flow rate Qc, and the air flow rate Qa is calculated based on the increase/decrease in the pressure in the intake manifold 21 in the air flow rate Q11. This corresponds to the sum of the amount ΔCM.

In step 22, the air flow rate Qc is set as Qco in preparation for the next calculation. Note that in steady state, of course ΔCM ” 0
, Q u = Q c = Q II.

FIG. 5 shows a calculation routine for the fuel injection amount Ti of the fuel injection valve 12. In the case of the single point-in-no-ejection method as shown in FIG. ' p is + Mf air tI
It is obtained by subtracting the atmospheric pressure correction coefficient Kp, the intake temperature correction coefficient KL, and the constant Ka to the L amount Qa.

For example, when applying to a multi-point injection system in which a fuel injection valve is installed in each intake boat, go to steps 30 to 32, and the basic injection amount 'I''
p is the air flow m Q c with an atmospheric pressure correction coefficient Kl'J+
Intake temperature? It is obtained by subtracting the stop coefficient Kt and the constant Ka.

Then, in step 33, each basic injection amount 'rp is determined according to C) the various correction coefficients C0EF used, and the air-fuel ratio sensor 1.
By calculating the feedback correction coefficient LA from 7 and further adding the invalid pulse width (voltage correction amount) i's, "C fuel injection 1t'l"i is obtained.

Note that each routine is executed at predetermined time intervals or in synchronization with engine rotation.

In this way, since the air flow fft Q II is calculated based on the opening degree a of the throttle valve 10 (and the opening degree of the bypass passage 19 of the throttle valve 10) and the engine rotational speed N, the hot wire type flow rate sensor It is not affected by intake pulsation like when a pressure sensor is used, and good responsiveness can be maintained during transients when engine operating conditions change, allowing accurate air flow rate Q11 to be maintained. Detection value is obtained.

On the other hand, the air flow l Q 11 does not match the air flow ff1QC flowing into the cylinder due to the air flow delay except in steady state, but the air flow delay corresponds to the throttle valve opening α and the engine speed N. By correcting the air flow rate Q11 using the delay coefficient K based on a and N, the air flow rate Qc to the cylinder during the transient period can be accurately determined.

Therefore, in the case of the multi-point injection method, accurate fuel injection control is possible by calculating the fuel injection amount based on the airflow 1i1Qc, and this allows for accurate fuel injection control during acceleration and deceleration IL? There is no excess or shortage of the fuel injection amount]i, and an appropriate air-fuel ratio can be maintained as in the steady state 1 o'clock.

Acceleration to figure 110) 1. The operating characteristics of ′f are as follows: aperture f
As the air flow rate Qll corresponds to the sudden opening of Plo, the air in the cylinder increases to iIt+i (C gradually increases to 7), and at this time, the intake boat If fuel is injected into the air, the air-to-air ratio will increase to 7 (same as in the conventional example), but by injecting fuel according to the air flow rate Qc, a more or less constant air-fuel ratio can be obtained. It is.

In light of this, in the case of the single point injection system, the fuel injection amount is calculated based on the air flow rate Qa passing through the fuel injection valve 12, and fuel injection control is performed. This air flow rate Q u is the air flow rate Ql+
It is obtained by adding t7: ΔCM corresponding to the increase/decrease in the pressure in the intake manifold 21 to .

Here, lie JIL in steady state of air flow rate Q a, Q Il, Q c is Q uo, Q IIo, Q
as co (Q uo= Q IIo= Q co)
, when Qllo becomes QH due to the opening operation of the throttle valve 10,
As shown in FIG. 11, Qc flowing into the cylinder is Q c
It gradually increases from o and reaches equilibrium at -CQ II, and after momentarily increases from Q al, t Q uo of the fuel injection section, it gradually decreases and reaches equilibrium at Qll, but at this time Qa and Q
Qc increases according to the difference from 11, and therefore the addition amount ΔCM ';-
Qu can be found by adding it to Qll.

It is confirmed by 'A fold that the air flow rate Q, detected in this way, coincides with the true value flow rate4. In this case, by adding ΔQc multiplied by a predetermined value to Qc, Qa can be calculated. Although it is possible to calculate it, the above method of adding ΔCM to Q Il is better than converting Q II to JI! ; Since it is based on the standard, values with less error can be obtained.

Therefore, in the case of the single-point inno-ection system, accurate fuel injection control is possible, and an appropriate air-fuel ratio can be maintained at all times according to the air flow + IQ, such as during steady state, acceleration, deceleration, etc.

Fig. 12 shows the operating characteristics during acceleration.
In response to the sudden opening of the throttle valve 1o, the air flow fiLQ passing through the fuel injection section upstream of the throttle valve 10 temporarily increases and then decreases. When injected, the air-fuel ratio becomes extremely lean (conventional example)
However, by injecting fuel according to the air flow rate Qu, 1
It is possible to inhale a mixture with a constant air-fuel ratio of approximately 1 into the cylinder.

Furthermore, as shown in Figures 10 and 12, the air-fuel ratio is somewhat lean! It becomes 1111, but this is a difference of one beach due to the fact that the fuel in the intake pipe is accelerating;

(Effects of the Invention) As described above, according to the present invention, the throttle valve opening pattern and the
Constant ° old calculated from IIA speed? By correcting the air flow rate at the operating state;
The air flow rate to the cylinder at the time can be detected accurately, and by adding a predetermined amount,
The flow rate of air passing through the fuel injection part can be detected accurately, so the multi-point injector type and the single-point injector type can detect transient H,
To the exact sky of f, the northern squirrel becomes Town 1-ni.

The simple + 1i of the drawings, 1, 1, 1, 1, 1, 1, 2, 2, 2, 3, 3, 5, 5, 1, 1, 5, 1, 1, 1, 1, 1, 1, 1, 1, 2, 1, 2, 2, 2, 2, 2, 2, 2, 3, 5, , 5, and s- 1, respectively, are the contents of each preparatory body. 6 to 9 are characteristic diagrams showing the contents of each table used for calculations, FIGS. 10 and 12 are explanatory diagrams showing operating characteristics during acceleration, and FIG. 11 is a diagram showing each table content during acceleration. FIG. 3 is an explanatory diagram showing the relationship between air flow rates.

DESCRIPTION OF SYMBOLS 1... Throttle valve opening detection means, 2... Engine rotational speed detection means, 3... Steady air flow rate detection means, t... Delay coefficient calculation means, 5... Delay correction means, 6 ... Addition, quantity element means, 7... Air flow) addition means.

Figure 4 Figure 6 Figure 7 l5CD (%) Figure 8 Figure 9 A (Cm2) Figure 10' Figure 11

Claims (1)

[Claims] A means for detecting the throttle valve opening, a means for detecting the engine rotation speed, a steady air flow rate calculation means for calculating the steady air flow rate from both detected values, and an air flow delay coefficient calculated from both detected values. delay coefficient calculation means for calculating the air flow rate flowing into the cylinder from the steady air flow rate and the delay coefficient; addition amount calculation means for calculating a predetermined addition amount from the calculation value of the delay correction means; An air amount detection device for an internal combustion engine, comprising an air flow amount calculation means and an air flow amount addition means for calculating a flow rate of air passing through a fuel injection section from the calculated values of both the air flow amount calculation means and the addition amount calculation means.