JPS60195345A - Air-fuel ratio controller for internal-combustion engine - Google Patents

Abstract

PURPOSE:To make an air-fuel ratio at a transient state flat, and improve drivability as well as to reduce harmful exhaust gas, by making a fuel injection quantity so as to be compensated in due to consideration of a phase difference between fuel injection timing and suction timing at a time when an engine is in the transient state of acceleration and deceleration conditions. CONSTITUTION:A suction air passing sectional area An is measured out of a throttle opening sensor 17 at every fuel injection timing from an ignition coil 14, and this variation DELTAA=An-An-1 is calculated. An engine speed N is measured out of the ignition coil 14 while suction pipe pressure P is measured out of a suction pipe pressure sensor 10, and a fundamental injection quantity Tp=K1. P is calculated. K1 is a proportional constant. Judging that the DELTAA>= specified value is an accelerating condition and the DELTAA< specified value is a steady condition, a compensation value KACC of a fuel injection quantity is calculated, and K2/N commensurate to a phase difference (time difference) DELTAt between fuel injection timing and suction timing is calculated. In order to make an air-fuel ratio flat, the phase difference DELTAt is compensated with the compensation value KACC. In addition, injection takes place at the fuel injection quantity Ti=KACC. Tp.

Description

[Detailed Description of the Invention] (Technical Field) The present invention relates to an air-fuel ratio control device for an internal combustion engine, and more particularly, to an air-fuel ratio control device for an internal combustion engine that corrects the air-fuel ratio in transient states such as engine acceleration/deceleration conditions. This invention relates to an air-fuel ratio control device.

Here, in this invention, "acceleration/deceleration condition" refers to a control state in which the engine is accelerated or decelerated, and more specifically, it refers to a transient state in which a throttle valve provided in the intake pipe of the engine is opening. "Acceleration condition", the closing transient state is "
"deceleration conditions".

The present invention also provides an air-fuel ratio control device for an internal combustion engine using the so-called "D-JETRO method," which measures the pressure of intake air, determines the fuel injection amount based on the measured intake pipe pressure, and controls the air-fuel ratio. It is related to.

(Prior Art) As an example of a conventional air-fuel ratio control device for an internal combustion engine using the D-Je system, there is one shown in FIG.
(Refer to "New Automotive Engineering Handbook (No. 4m)" published by the Society of Automotive Engineers of Japan on September 30, 1981).

In the same figure, fuel is transferred from Tool Tank 1 to Fuel I.
It is sucked into the tube f2 and fed under pressure. Next, the pulsation is suppressed by Funerdan Gu3. Next, after dust is removed by a Tsuyuel filter 4, the fuel is supplied to an injector 5. Further, the Zoresha V-gealator 6 operates so that the difference between the pressure of the fuel supplied to the injector 5 and the internal pressure of the intake pipe 9 is constant.

The air is sucked in from the air cleaner 7 to remove dust, the intake air amount is adjusted by the throttle valve 8, the intake pipe pressure P is detected by the intake pipe pressure sensor 10 in the intake pipe 9, and the air is mixed with the fuel injected from the injector 5. , the mixture is 1 for each cylinder
1.

The control unit 12 includes, in addition to the intake pipe pressure P signal from the intake pipe pressure sensor 10, a cooling water temperature signal from the water temperature sensor 13, a negative terminal signal of the ignition coil 14,
A throttle valve opening θ signal from a throttle valve opening sensor 15 mounted coaxially with the throttle valve 8 is input.

In the control unit 12, first, the intake pipe pressure P is measured from the output of the intake pipe pressure sensor 10, and this is multiplied by a proportionality constant to set the basic injection amount Tp=.P. Next, a correction coefficient KTW according to the output of the water temperature sensor 13,
Correction value T according to battery voltage! The fuel injection amount Ti=KTw-Tp+Ts is determined by l.

The timing for injecting fuel includes timing synchronized with the engine rotation determined from the ignition signal of the ignition coil 14, and interrupt timing under acceleration conditions.

As shown in Figs. 2 and 3, the interrupt timing under acceleration conditions is such that the interrupt injection is performed each time the comb teeth attached to the throttle valve opening sensor 15 are turned on and off. In conventional air-fuel ratio control devices for internal combustion engines, there is a phase difference (time difference) between the fuel injection timing and the intake timing, which are synchronized with the engine rotation.
Because the fuel injection amount was determined without taking this phase difference into account, if the required injection amount for one engine changes after fuel injection until intake during transient operation, the amount of change will be reflected in the air-fuel ratio. For example, under acceleration conditions, the actual injection amount is insufficient compared to the required injection amount, and the air-fuel ratio becomes lean.

Therefore, in order to compensate for such a fuel shortage, under acceleration conditions, the comb tooth switch attached to the throttle valve opening sensor is turned on.
Interrupt injection is performed every time the engine is turned off, but with corrections that rely on such interrupt injections, the amount of correction must be set with a considerable margin to avoid poor acceleration, which may lead to overconcentration. emissions, especially CO
There was a problem that the exhaust gas components of 1-1c and 1-1c increased.

In order to improve this problem, the above phase difference can be reduced.
It is conceivable to bring the fuel injection timing closer to the intake timing, but if it is brought too close, the atomization of the fuel will worsen, causing problems such as a decline in performance during idling, which is not a good idea.

(Object of the Invention) The present invention has been made by focusing on such conventional problems, and it is an air-fuel ratio of an internal combustion engine based on the D-noeto method, which determines the amount of fuel supplied according to the intake pipe pressure of the engine. The control device corrects the fuel injection amount, taking into account the phase difference between fuel injection timing and intake timing, especially under acceleration/deceleration conditions, flattens the air-fuel ratio during transient conditions such as acceleration/deceleration conditions, and improves drivability. , aiming to reduce harmful exhaust gases.

(Structure and operation of the invention) FIG. 4 is an overall configuration diagram clearly showing the structure of the invention.

As shown in the figure, an intake pipe 9 of the internal combustion engine is provided with an intake pipe pressure sensor 10 for detecting intake air pressure P and a throttle valve opening sensor 17 for detecting the opening of the throttle valve 8. The intake air cross-sectional area detection means detects the intake air passage cross-sectional area A near the throttle valve 8 and outputs it to the transient state determination means and the correction value calculation means. The transient state determining means determines whether the internal combustion engine is in a transient state based on the detected intake air passage cross-sectional area A, and outputs the determination result to the intake pipe pressure P(.) detecting means and measuring means. The intake pipe pressure P(.) detection means detects the intake pipe pressure P(o) immediately before the start of the transient state based on the intake air pressure P detected by the intake pipe pressure sensor 10 and the output signal of the transient state determination means. The time measuring means measures the elapsed time time from the start of the transient state based on the output signal of the transient state determining means. The rotation speed detection means detects the rotation speed N of the internal combustion engine.

The intake air passage cross section J/iA obtained as above, the elapsed time time, the intake pipe pressure P(.), and the rotation speed N.
, the correction amount K in the transient state for the basic fuel injection amount T,
is preferably calculated based on the following formula.

However, Pa is the atmospheric pressure, ■ is the intake pipe volume, and Δ[ is the phase difference Δ between fuel injection and intake valve opening.

The fuel injection amount calculation means calculates a basic fuel injection amount T from the intake air pressure P and the rotational speed N, and multiplies this value T by the correction value K to calculate an actual fuel injection amount T1. Outputs a signal to drive the injector.

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

FIG. 5 shows an embodiment of an air-fuel ratio control device for an internal combustion engine according to the present invention. The difference from the conventional device described above lies in the internal configuration and operation of the control unit 16 and the configuration and operation of the throttle valve opening sensor 17. Other components are designated with the same reference numerals as in FIG.

FIG. 6 i is a block diagram showing the configuration of the control unit 16 of FIG. 5; In the figure, intake pipe pressure sensor 10. Each output signal from the throttle valve opening sensor 17 and the water temperature sensor 13 is input to a multiplexer 18 . This multiplexer 18 is switched by a launch circuit 19 operated by a signal from the ignition coil 14, and each sensor output is converted into A/I by a φ converter 20. Further, the signal from the ignition coil 14 is counted by a counter 21, and the engine rotation speed N is determined.

Based on the sensor outputs converted by the A/D converter 20 and the engine rotational speed N from the counter 21, the calculator 22 performs calculations shown in a flowchart (FIG. 9) to be described later. In this case, memory 23 is used.

The fuel injection width T and force calculated by the calculator 22 are written in the register 24, and the drive circuit 27 is operated by the comparator 25 for the time T1 measured by the timer 26 to drive the injector 5.

The control unit (control circuit) 16 described above can be easily realized using a microcontroller.

The throttle valve opening sensor 17 has a configuration as shown in FIG. That is, in the same figure, 17a is a resistor L1
7b is a brush that rotates coaxially with the throttle valve shaft 17c and contacts the resistor 172. A constant voltage (for example, 5V) is applied between terminals 17d and 17e of resistor 17a, and the output of throttle valve opening sensor 17 is generated from terminal 17f of brush 17b.

FIG. 8 shows the output characteristics of this throttle valve opening sensor 17.

That is, the terminal 17f for the throttle valve opening degree θ shown in FIG.
shows the output voltage of 5 to terminal 17e for terminal 17d.
When v is applied, the output of terminal 17f is (1-μsθ)x
5 (V), which represents the intake air passage cross-sectional area A of the throttle valve portion when the throttle valve opening degree is θ. In other words, the shape of the resistor 17a is set so as to provide the characteristics shown in FIG.

The conventional throttle valve opening sensor 15 (Fig. 1) measures the throttle valve opening of 0, and calculation is required to calculate the intake air passage cross-sectional area A from this θ. The 17% degree sensor has the advantage that the intake air passage cross-sectional area A can be directly measured.

Next, the operation of the present invention will be explained using the flow chart of FIG. 9 and the time chart of FIG. 10, taking as an example the case where the fuel injection amount is corrected in a transient state due to acceleration.

First, at each fuel injection timing from the ignition coil 14,
The intake air passage cross-sectional area An is measured from the throttle valve opening sensor 17 and stored (step f31). Next, the previous intake air passage cross-sectional area A. -1, the amount of change ΔA-An-An-1 in the intake air passage cross-sectional area is calculated (step f32).

Next, the ignition signal of the ignition coil 14 and the engine rotational speed N are measured (step 33).

Furthermore, the intake pipe pressure P is measured by the intake pipe pressure sensor 1o, and this P is multiplied by a proportionality constant to calculate the basic injection amount Tp=.P (step 35).

Next, the ΔA obtained in step 32 is compared with a predetermined value (Step 7036), and if YES (ΔA≧predetermined value), the engine is determined to be in an acceleration condition, and if NO (ΔA × predetermined value), the engine is determined to be in a steady condition. do.

If YES (acceleration condition), check the acceleration flag (step 37). If the acceleration flag = 0, it means that the condition has been steady and acceleration has started, so the acceleration flag should be set to 1 (step 38), and then time
= O (step 39). Then, a correction value KACC for the fuel injection amount is calculated (step 43).

If the result in step 36 is No (steady condition), the acceleration flag is also determined (step 40). If the acceleration flag=1 in step 40, it is determined that the acceleration condition has ended, and the acceleration flag is set to -0 (step 41). Next, Ste.
If NO in Step 40 and YES in Step 37, count up the time and set time =
time 10 to 27N (Ste.

42). Here, K2 is a proportional constant, N is the engine speed, and K2/N corresponds to the phase difference (time difference) Δt between the fuel injection timing and the intake timing. Next, the correction value KA
CC is calculated (step 43). 'Next, step 4
The method of calculating the fuel injection amount correction value KAcc in No. 3 will be explained.

When the throttle valve 8 is changed stepwise, the intake air passage cross-sectional area A also becomes A as shown in FIG. 10(a). It changes stepwise from A1 to A1. In response to this change, the intake pipe pressure P transiently exponentially becomes rhombic from the intake pipe pressure P (0) immediately before the change until the change ends and the steady state intake pipe pressure P1 is reached. As shown in figure (b), it changes as follows. (1)
In the formula, ■ T-... (3) C3N0C,A. However, time: Elapsed time from the start of acceleration C4IC2, C3: Constant Pa: Atmospheric pressure ■: Intake pipe volume A: Intake air passage cross-sectional area N: Engine speed Furthermore, as mentioned above, fuel injection timing and intake timing There is a difference, and therefore the intake pipe pressure when the fuel is actually drawn into the cylinder and the intake pipe pressure measured for fuel injection are not the same, and there is a phase difference of ΔtK2/N. Here, the intake timing refers to the maximum lift of the intake valve as a reference.

Therefore, in order to keep the air-fuel ratio constant under acceleration conditions, it is necessary to correct this phase difference Δ, and the correction value KA shown below is
Use CC.

P++(P(.)-P,)·e τ The correction value KACC of equation (4) changes as shown in FIG. 10(e).

Returning to FIG. 9, the correction value KAC calculated in this way
Multiply C by the basic injection amount Tp determined in Stella f35 to arrive at the fuel injection amount T1=KAco-Tp (step f44, FIG. 10(d)), and inject fuel at this Ti (step 45).

As a result, as shown in FIG. 10(f), the air-fuel ratio remains constant as shown by the broken line even under transient conditions of acceleration, improving drivability and reducing harmful exhaust gases. If such a phase difference is not corrected without consideration, the air-fuel ratio will fluctuate under acceleration conditions, as shown in FIG. 10(g).

In addition, the broken lines in FIG. 10(c) and FIG. 10(d) are
It represents the basic injection amount Tp obtained by multiplying the intake pipe pressure P by the proportionality constant by 1 according to equation (1) (FIG. 10(b)).

Although the case of the acceleration condition has been described above, the case of the deceleration condition can also be carried out in substantially the same manner as the flowchart of FIG. 9.

That is, even in the case of a deceleration condition, in step 36 of FIG. 9, the amount of change ΔA in the intake air passage cross-sectional area is compared with a predetermined value, and if Δ8 is smaller than the predetermined value, it is determined that the deceleration condition is present. Similarly to step 43, by correcting the basic injection amount Tp using the correction value of equation (4), the air-fuel ratio under deceleration conditions can be made flat in the same way. −In this case, Δ
If the absolute value of the predetermined value to be compared with A is the same as the predetermined value for acceleration condition determination, acceleration/deceleration is determined under the same conditions by taking the absolute value of ΔA and comparing it with a positive predetermined value. be able to.

The acceleration/deceleration conditions of the engine can be determined by determining whether the amount of change ΔP in the intake pipe pressure P of the engine is greater than or equal to a predetermined value, in addition to the method based on the displacement amount ΔA of the intake air passage cross-sectional area A of the throttle valve 8 portion described above. The determination may be made based on the following.

Also, correction values KACC and K. 2c may be further corrected depending on the engine cooling water temperature, and basically, the lower the cooling water temperature, the lower the correction values KACC and KD. Make it even bigger.

(Effects of the Invention) As explained above, according to the air-fuel ratio control device for an internal combustion engine of the present invention, the phase difference between the fuel injection timing and the intake timing is taken into consideration in a transient state such as an acceleration/deceleration condition of the engine. Since the fuel injection amount is corrected, the air-fuel ratio in a transient state can be kept constant (brush 1), improving drivability and reducing harmful exhaust gases.

[Brief explanation of drawings]

Fig. 1 is a block diagram of an air-fuel ratio control device for an internal combustion engine using the conventional D-noetro system, Fig. 2 is a plan view showing the structure of a conventional throttle valve opening sensor, and Fig. 3 is a diagram of the throttle valve of Fig. 2. FIG. 4 is a functional block diagram showing the configuration of the present invention. FIG. 5 is a configuration diagram of an embodiment of the air-fuel ratio control device for an internal combustion engine of the present invention. FIG. 7 is a block diagram showing the configuration of the control unit in FIG.
Fig. 8 is a diagram showing the configuration of the throttle valve opening sensor used in the present invention, Fig. 8 is a diagram showing the characteristics of the throttle valve opening sensor shown in Fig. 7, and Fig. 9 is a diagram showing the air-fuel ratio control of the internal combustion engine of the present invention. A flowchart explaining the operation of the device, and FIG. 10 is a time chart showing changes in each parameter. 5... Injector, 10... Intake pipe pressure sensor, 11
... cylinder, 14 ... ignition coil, 16 ... controller 1
Roll unit, 17... Throttle valve opening sensor, 17a...
...Resistor, 17b...Brush, 21...Counter,
22... Arithmetic unit, 27... Drive circuit, A... Cross-sectional area through which intake air passes KACCI KDEC... Correction value, N
...Engine speed, P...Intake pipe pressure, P(.)...
Intake pipe pressure just before the start of acceleration/deceleration, T.・Basic injection amount, T1 ・・Fuel injection amount, time: Elapsed time from the start of acceleration/deceleration, Δt: Phase difference, θ: Throttle valve opening. Patent Applicant Nissan Motor Co., Ltd. Patent Application Agent Megumi Yamamoto - Maku 7 Diagram 8 Figure 3Lt/r7I

Claims (2)

[Claims] (1) An intake pipe pressure sensor that detects the intake air pressure P of the internal combustion engine, a throttle valve opening sensor that detects the opening of a throttle valve provided in the intake pipe, and a throttle valve opening sensor that detects the opening of the throttle valve provided in the intake pipe. an intake air passage cross-sectional area detecting means for detecting the intake air passage cross-sectional area A of the throttle valve portion; a transient state determining means for determining the presence or absence of a transient state of the internal combustion engine based on a signal from the means; Based on the elapsed time from the start of the transient state Lirne
an intake pipe pressure P(.) detection means for detecting the intake pipe pressure P(.) immediately before the start of the transient state based on signals from the transient state determination means and the intake pipe pressure sensor; A rotation speed detection means for detecting the rotation speed N of the internal combustion engine, and a correction value K in a transient state from the intake air passage cross-sectional area A, the elapsed time time, the intake pipe pressure P(o), and the rotation speed N.
a correction value calculation means for calculating a basic fuel injection amount T from the intake air pressure P and the rotational speed N, and calculates an actual fuel injection amount Ti by multiplying the value Tp by the correction amount K. 1. An air-fuel ratio control device for an internal combustion engine, comprising: fuel injection amount calculation means for outputting a signal for driving an injector. (2) The correction amount includes: pa is the atmospheric pressure, ■ is the intake pipe volume, and ΔL is the phase difference Δt between the time of fuel injection and the time of opening the intake valve. An air-fuel ratio control device for an internal combustion engine according to scope 1.