JPS59185834A - Fuel feed device of internal-combustion engine - Google Patents

Abstract

PURPOSE:To correct the fuel feed quantity in response to the air quantity sucked into a cylinder when the throttle valve opening is changed abruptly and stabilize the feed quantity using the change of the air quantity as a parameter when the throttle valve is in a condition other than that fully closed. CONSTITUTION:A control unit 31 constituted as shown in the figure is fed with signals from a full-close switch 32 which is turned ON when a throttle valve 17 is fully closed and is turned OFF otherwise, an air flow meter 15 detecting the air quantity of an intake pipe, an engine speed sensor 33 outputting a signal at every engine rotation, and a reference signal generator 34 respectively. These signals are arithmetically processed by the unit 31 in required processing steps; when the opening of the throttle valve is abruptly changed to the increasing direction, the augmentation of the air quantity sucked into the intake pipe is delayed, thereby the correction function is decreased to decrease the fuel injection quantity; when the opening is rapidly changed to the decreasing direction, the decrease of the air quantity sucked into the cylinder is delayed, thereby the correction factor is increased to increase the fuel injection quantity.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fuel supply system for an internal combustion engine, and more specifically, the present invention aims to appropriately control the air-fuel ratio during transient operation in which the throttle valve opening changes suddenly, stabilize combustion, and improve operating performance. The present invention relates to a fuel supply device.

As a conventional fuel supply system for an internal combustion engine, one that combines, for example, a fuel system shown in FIG. 1, an air system and an electronic control system shown in FIG. 2 is known.

In the fuel system shown in Figure 1, the fuel is in the Tsuyuel tank 1.
It is sucked in by the Tsuyuel pump 2, pressurized, and pumped out. Next, the fuel damper 3 damps the fuel pulsation generated by the fuel pump 2, and the fuel filter 4
After dust and moisture are removed by the pressure regulator 5, the fuel is regulated to a constant fuel pressure and is injected into the injector (fuel injection valve) 10 attached to the intake pipe 9 near the intake valve 8 of each cylinder tough of the engine 6. From then on, fuel is injected at a predetermined time for a predetermined injection amount T (injection time) calculated by the control unit 11 as described later.

Incidentally, surplus fuel is returned to the tsuyuel tank 1 from the pressure regulator 5. 12 is a water temperature sensor that detects the temperature of the cooling water; 13 is a cold start valve that is opened to increase the amount of fuel supplied when starting the engine when the temperature of the cooling water is low.

The air system is as shown in Figure 2.
The intake air amount Q is measured by the air flow meter 15, the intake air amount Q is adjusted by the throttle valve 17 in the throttle chamber 16, and the air is injected from the above-mentioned injector 10 in the intake pipe 9. The air-fuel mixture is supplied to each cylinder 7 after being mixed with the fuel. The throttle chamber 16 has a valve that is OFF when the throttle valve 17 is open and ON when the throttle valve 17 is closed.
A throttle switch 18 is attached.

19 is a bypass passage for intake air when the throttle valve 17 is closed (i.e., idling); 20 is an idle axis 1 for adjusting the air flow rate in the bypass passage 19;
- The screw, 21, is an air regulator that serves as an auxiliary air valve to increase the amount of air during startup and subsequent warm-up operation.

Next, the electronic control system uses the intake air amount Q signal from the air flow meter 15 and the crank angle sensor attached to the crankshaft of the engine 6 in the control unit 11. J
- Basic injection amount T based on the engine speed N signal from 22.
p Tp=K (Q/N) (K is a constant)...(1)
Calculate. Furthermore, by inputting various information detected on the state of the engine and each part of the vehicle, correction of the injection amount is calculated to determine the actual fuel injection amount T. Based on this T, the injector 10 is simultaneously injected into each cylinder at a rate of 1.5 times per engine rotation. Drive times.

To explain the various corrections in detail, the battery voltage correction Ts as a correction due to fluctuations in the drive voltage of the injector 10 is
As shown in the figure, Ts=a-1-b (1,4-VB> (however, a
, b is a constant) ...(2) is given by the following.

The water temperature increase correction Ft when the engine is not sufficiently warmed up is:
It is determined from the characteristic diagram shown in FIG. 4 according to the water temperature.

Increased amount correction KAs after starting to obtain smooth starting performance and to smoothly connect from starting to eye 1-ring
is the initial value KAso when the starter motor is turned on
is determined from the characteristic diagram shown in FIG. 5 according to the water temperature at that time, and thereafter decreases to 0 with the passage of time.

In order to use the internal fan when starting when warm-up has not been performed sufficiently, increase the amount after idling correction KAi, throttle switch 1
The initial value KAi (+) when 8 is turned off is determined from the characteristic diagram shown in Fig. 6 according to the water temperature at that time.
It decreases to 0 with the passage of time (.

In addition, correction using an exhaust sensor may be performed.

Furthermore, the following control is performed when starting the engine.

T+=TpX (1-1-KAs)Xl, 3→-'7''
s − t: 3) T 2 = T S T X K N
S T

However, TST, KNST, and KTST in equation (4) are respectively determined by the water temperature, engine speed, and time elapsed after startup.
It can be obtained from the characteristic diagrams shown in FIGS.

However, in such conventional devices, the basic injection amount, which is set as a value proportional to the air amount q taken into the cylinder, is always determined as Tp = -Q/N, but during transient operation, the basic injection amount is set as a value proportional to the air amount q taken into the cylinder. Since there is a delay in the change in the amount of air q taken into the cylinder with respect to the change in the amount of air Q taken into the cylinder, it is not possible to set ゛p to a good value, which has an adverse effect on drivability.

For example, as shown in Figure 0, when the throttle valve is not fully closed, even when the ζ opening changes suddenly, there is a delay in the change in q with respect to the change in Q, and overshoot due to the inertia of Q occurs. [- and undershading also causes overshoots and undershoots in the fuel supply amount, resulting in problems such as poor driving.

The present invention has been made in view of these conventional problems, and provides a fuel supply system for an internal combustion engine that stabilizes the air-fuel ratio and improves transient operation performance during transient operation when the throttle valve opening of the engine changes suddenly. The purpose is to provide.

Therefore, in the present invention, a means for detecting the opening degree of the throttle valve, a means for detecting a change in the amount of air taken into the intake pipe, and a means for detecting a change in the amount of air taken into the intake pipe are provided, and the throttle valve is fully operated based on signals from these detecting means. The configuration includes means for correcting the fuel supply amount using a change in the amount of air taken into the intake pipe when the intake pipe is not closed as a parameter.

The present invention will be explained below with reference to the drawings.

However, since the fuel system and air system of the engine are the same as those of the conventional example shown in FIGS. 1 and 2, the same reference numerals will be used to describe them.

FIG. 11 is a block diagram showing one embodiment of the present invention.

In the figure, the control unit l□31 includes a throttle fully closed switch 32 that is turned on when the throttle valve 17 is fully closed and turned off otherwise, an air flow make 15 that detects the amount of air taken into the intake pipe, and an engine. Signals are input from a rotational speed sensor 33 that outputs a signal every time the engine rotates by 1°, and from a reference signal generator 34 that outputs a signal every time the engine rotates once.

The control unit 31 is composed of units that perform f&j. That is, the A/D converter 35 performs analog-to-digital conversion on the signal from the air flow make 15, and outputs a digital intake air amount Q signal.

The pulse counter 36 counts pulse signals every 1 degree from the rotation speed sensor 33 and outputs an engine rotation speed N signal. The arithmetic circuit 37 operates on these fully open throttle switches 32. A
/Di converter 35. Pulse counter 36. Based on the signals from the reference signal generator 34 and memory 38, the operation is performed as shown in flowchart 1- of FIG. First, the intake air amount Q is transferred to the memory 38 every predetermined period (predetermined time or predetermined rotation) (Sl).

Second, after reading the current and previous engine speed N and intake air iQ (S2), it is determined whether the throttle/7 torque valve fully open switch 32 is ON or not.
), if it is ON, read it in S2 and calculate the basic injection amount T p = K・Q/N from Q and N (S4)
.

In addition, if it is determined in S3 that the throttle fully open switch 32 is OFF, the intake air amount changes based on the current intake air read in S2 (iQ and the intake air manually input from the memory 38 + JQ' for a predetermined period of time). Minute ΔQ=Q-Q
' (S5), and the correction function Foff (ΔQ) set based on this ΔQ and the output Q of the A/D converter
From the above N, the basic injection amount Tp=Foff (ΔQ)
・Calculate K-Q/N (S6) Next, based on Tp obtained in this way, the final fuel injection amount Ti is calculated by making corrections based on various operating conditions as in the conventional method described above. (S7) and transfers the signal to the register 39 (S8)
)-6 register 39 temporarily stores this value until a new signal is input from the arithmetic circuit 37. Further, the clock generator 40 emits pulses having a predetermined frequency, and the counter 41 is reset by a reference signal from the reference signal generator 34 in response to the pulses from the clock generator 40. When the comparator 42 inputs the reference signal from the reference signal orderer 34, it turns off the transistor 43.
The injector 10 is energized to open and start injecting fuel, and the value of the register 39 (i.e. fuel injection amount T i ) is compared with the value of the counter 41.
When the value increases to the value of the register 39 minus the value of the counter 41, the transistor 43 is turned on, the injector 10 is closed, and fuel injection is completed (see FIG. 13).

Here, the correction function Foff(ΔQ) used in S5 and S7 of the arithmetic circuit 37 is set, for example, as follows.

That is, when a, ΔQ≧Qα, Foff (△Q)≦1. O
b, when Qα>ΔQ>Qβ, Foff (ΔQ)='1. OC1ΔQ≦Qβ, off (80)≧1,
0 provided that Qα≧0. Qβ≦0. Foff (80)
≧0. That is, as mentioned above, when the throttle valve suddenly changes in the direction of increasing opening (a), the increase in the amount of air Q taken into the intake pipe lags behind the amount of +ItJ of air taken into the cylinder. Since there is a correction function Fof
When f(ΔQ) is decreased to correct the fuel injection amount, and on the other hand, when the opening changes suddenly in the direction of decreasing opening (C), there is a delay in decreasing the amount of air taken into the cylinder, so the correction function Fo
By increasing ff(ΔQ) and increasing the fuel injection amount, a fuel amount that satisfactorily corresponds to the true cylinder intake air amount is supplied, the air-fuel ratio is stabilized, and drivability is improved.

By using the following value as the amount of change ΔQ in the amount of intake air, it is possible to prevent malfunctions due to variations in detection of the amount of change, etc., and to achieve more optimal control.

1) Difference (Q-Q') between the current value Q and the average value or weighted average value (Q゛) of the past predetermined period (Q-Q')ii) Difference between the current value Q and the average value or weighted average value (Q゛) of the latest predetermined period including the present )
and the average value or weighted average value (Q゛) of the past predetermined period (Q-Q'') 111) The above embodiment and the above i)
, ii) (weighted average value of any one of them (ΔQ=(1-a)80' +a-Q)iv) Difference (Q-Q' in the above example and i), ii) above
), (Q-Q"), (Q-Q'), the moving average value of any one (ΔQ-removal ΔQ i ) FIG. 14 shows a flowchart of the second embodiment of the present invention. However, since the configuration other than the operation of the arithmetic circuit is the same as that of the previous embodiment, a description thereof will be omitted.

As in the previous embodiment, the arithmetic circuit transfers the current amount of air Q taken into the intake pipe to the memory 38 at predetermined intervals (Sll). On the other hand, after reading N and Q (S
12) Calculate the basic injection amount 1-p (-Q/N) (S13).

Next, it is determined whether the throttle fully closed switch 32 is ON or not (514), and if it is ON, the process directly proceeds to S17, which will be described later.

In addition, if the full throttle switch is OFF at 314, first calculate the change (ΔQ=Q-Q'') from the current intake pipe intake air amount Q and the intake pipe intake air amount Q'' from a predetermined period before.
(S15), and from this ΔQ, the fuel correction bone Goff
(ΔQ) is added to the above ]p and the result is re-set as Tp (316).

Next, based on the Tp obtained in 313 or the Tp corrected in S16, the conventional correction calculation is performed to obtain the final fuel injection amount Ti, which is transferred to the register (317
).

Here, the fuel correction bone Goff (ΔQ) is assumed to be, for example, the following value.

d, when ΔQ≧jQα, C, off (ΔQ)≦O
e, when Qα〉80>Qβ, Goff (ΔQ)=O f, when ΔQ≦Qβ, Goff (ΔQ)≧0, however, Qα≧0. Qβ≦0 Note that the change in Q ΔQ may be the same as that shown in the above embodiment.

In this embodiment as well, by providing (adjusting or subtracting) a fuel correction value instead of multiplying by a correction coefficient, it is possible to correct the fuel supply amount that corresponds well to the true amount of air taken into the cylinder, and thus during transient operation. It is possible to stabilize the air-fuel ratio and improve drivability.

As explained above, in the present invention, when the throttle valve is not fully closed, a means for correcting the fuel supply amount using the change ΔQ in the amount of air taken into the intake pipe as a parameter is provided, so that when the throttle valve opening degree suddenly changes. It is possible to stabilize the air-fuel ratio and improve driving performance by correcting the fuel supply amount to suitably correspond to the amount of air taken into the cylinder.

[Brief explanation of drawings]

Fig. 1 is a configuration diagram of the fuel system of a conventional electronically controlled fuel supply device, Fig. 2 is a configuration diagram of the air system of the same device, and Fig. 3 is a characteristic diagram showing the relationship between the internal voltage and the internal voltage correction value. Figure 4 is a characteristic diagram showing the relationship between water temperature and water temperature increase correction value,
Figure 5 is a characteristic diagram showing the relationship between water temperature and the initial value of the increase correction after starting, Figure 6 is a characteristic diagram showing the relationship between the water temperature and the initial value of the increase correction after idling, and Figure 7 is the water temperature and correction value. A characteristic diagram showing the relationship between TST and Figure 8 shows the engine speed and correction value KNS.
Figure 9 is a characteristic diagram showing the relationship between the elapsed time after startup and the correction value KNST, and Figure 10 is a characteristic diagram showing the relationship between the time elapsed after starting and the correction value KNST, and Figure 10 shows the throttle opening, cylinder intake air amount, and fuel when the throttle opening of the conventional device suddenly changes. A diagram showing the behavior of the supply amount, FIG. 11 is a block diagram of an embodiment of the device according to the present invention, and FIG. 12 f
Al, (Bl is a flowchart showing the main operation of the device according to the above embodiment, FIG. 13 is an output waveform diagram of the main part of the device according to the embodiment above, and FIG. It is a flowchart showing main operations. 6... Engine 10... Injector 15...
・Air flow meter 31...Control unit 32...Throttle fully closed switch 33...Rotational speed sensor 34...Reference signal generator 35...
・A/D converter 36...Pulse counter 37...
・Arithmetic circuit 38...Memory 39...Regisf 40...Clock generator 41...
・Counter 42...Comparator 43...Transistor patent applicant Nissan Motor Co., Ltd. agent Patent attorney Fujio Sasashima Third cause 4th figure ice si ('C) 5th cause Shi Meng (0C ) No. 6 No. 7 Suehori - (0C) No. 8 No. of mouth rolls N (rl)m)

Claims (1)

[Claims] In a fuel supply system for an internal combustion engine in which a basic supply amount of fuel is set based on the amount of air taken into an intake pipe and the engine speed, means for detecting the opening degree of a throttle valve installed in an intake pipe; , means for detecting changes in the amount of air taken into the intake pipe, and based on signals from these detection means, changes in the amount of air taken into the intake pipe when the throttle valve is not fully open are set as parameters. 1. A fuel supply device for an internal combustion engine, comprising: means for correcting a fuel supply amount.