JPS5828543A - Electronically controlled fuel injection process and equipment in internal combustion engine - Google Patents

Abstract

PURPOSE:To enable performing proper fuel injection even in case where the air-flow meter is put slantwise, etc. in such a way that factors to be used when computing the reference injection rate from the inhaled air rate of the output from an air-flow meter and the number of revolution in the engine are adopted as the functions of the inhaled air rate. CONSTITUTION:An electronic control circuit 38 which takes output signals in from an air-flow meter 12, a cooling water temperature sensor 16, and other detectors computes the reference injection time Tp through the inhaled air rate Q related to the output from the air-flow meter 12, and through the number of revolution N in the engine in compliance with the formula Tp=K.Q/N. Hereat, the factor K is assumed as the function of the inhaled air rate Q as shown by the actual line (A) on the graph in order to prevent the air-flow meter from errors due to the slant putting of the air-flow meter 12. Thus, errors when detecting the inhaled air rate from the air-flow meter are made possible to be compensated when computing the reference injection time Tp using the above formula.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electronically controlled fuel injection method and device for an internal combustion engine, and in particular, it is suitable for use in an internal combustion engine for an automobile, and is suitable for use in internal combustion engines for automobiles. The basic fuel injection amount is calculated according to the rotational speed.5 [Regarding improvement of electronically controlled fuel injection method and device for internal combustion engines] Injecting a mixture with a predetermined air-fuel ratio into the combustion chamber of an internal combustion engine (referred to as an engine) One method of supplying fuel is by using a so-called electronically controlled fuel injection system.

In this method, an injector for injecting fuel into the engine is installed in the intake manifold or throttle body of the engine, for example, in several engine cylinders or in one engine cylinder, and the opening time of the injector is adjusted depending on the operating state of the engine. By controlling the air-fuel mixture, a mixture having a predetermined air-fuel ratio is supplied to the engine combustion chamber. There are various types of such electronically controlled fuel injection devices, but in recent years, digital electronically controlled fuel injection devices in which the electronic control circuit is digitalized have been developed. In such an electronically controlled fuel injection system, the amount of air intake into the engine is normally detected using an air meter, etc., and the engine speed is detected from an engine speed signal input from a distributor. The calculated basic fuel injection amount is corrected by signals according to the engine status etc. input from sensors installed in various parts of the engine, resulting in synchronous injection, which always injects at the same crank position in synchronization with the engine rotation. In order to improve startability or responsiveness immediately after acceleration, asynchronous injection is used in addition to normal synchronous injection, in which a predetermined amount of injection is performed only immediately after a signal from the Senna is received in accordance with the driving condition.

The synchronous injection time during which the injector is open in response to the synchronous injection is, for example, the basic injection time VC1 calculated using the intake air amount from the air meter and the rotation signal from the distributor. , by multiplying by a correction coefficient to correct the injection time according to the engine state at that time, such as when cold or accelerating, and further adding an invalid injection time to correct the injector operation delay due to voltage cost. It has been decided. The basic injection time is, for example, in order to improve engine startability,
When starting the engine, the amount of intake air is corrected at a predetermined time regardless of the intake air amount and engine speed, and the amount is increased for a certain period of time after the engine starts to stabilize the engine rotation immediately after starting. , the amount is increased after startup, and is increased when the intake air temperature is low in order to prevent deviations in the air-fuel ratio due to the increase in air density and air volume when the intake air temperature is low.
Therefore, the intake air temperature is corrected, and in order to ensure operability in cold conditions, the amount of cooling water is increased when the temperature is low.
In addition, in order to prevent sluggishness immediately after acceleration and improve acceleration performance, the amount is increased for a period of time immediately after acceleration to compensate for the increase in acceleration during warm-up. In order to increase the output, the output increase is corrected by performing increase 11 at a high load when the throttle valve opening is, for example, 6C3 or more, and furthermore, to bring the air-fuel ratio of the air-fuel mixture to a predetermined air-fuel ratio, for example, near the stoichiometric air-fuel ratio. , air-fuel ratio feedback correction is performed by changing the increase ratio according to the oxygen concentration in the exhaust gas. Also, in order to prevent overheating of the catalytic converter and save fuel consumption, or to forcefully suppress the vehicle speed, during engine braking, or
When the vehicle speed exceeds the specified maximum speed and the vehicle dies, fuel injection is stopped and fuel is cut.

Such an electronically controlled fuel injection device, particularly a digital electronically controlled fuel injection device, is characterized in that it is possible to control the fuel injection amount extremely precisely.

However, in the conventional electronically controlled fuel injection system, Q#, the detection of the intake air amount is inserted into the intake passage fixed to a rotatable shaft 12m, as shown in Figures 1 and 2. measuring plate 12b, the measuring plate 12bt--the return spring 12c that biases the intake passage in the direction of closing, and the shirt) 12M.
and a potentiometer 12d disposed at one end of the
The opening degree of the measuring plate 12b, which is determined by the balance between the force in the opening direction due to the air flowing in the intake passage and the force in the closing direction due to the return spring 12C1, is detected by the potentiometer 12d and outputted by the air flow meter 12. Due to the structure of the air flow meter, the measuring plate 12b
The opening degree of the measuring plate 12b is determined by the balance between the force received from the intake air flowing inside the air flow meter 12 and the force exerted by the return spring 1lcllC. The degree of influence of gravity differs depending on the type of intake air, and the intake air amount cannot be detected accurately. In the figure, it is a 12@tj convention plate. Furthermore, in the air floor meter described above, at high speeds or under high load when the amount of intake air is extremely large, the measuring plate 12b opens too much due to the pulsation of the intake air, resulting in an excessive measurement of the amount of intake air of the engine. The fuel injection amount may also become excessive, resulting in so-called over-rich condition.

The present invention has been made in order to eliminate the above-mentioned drawbacks of the conventional technology, and provides an electronically controlled fuel injection amount for an internal combustion engine that can calculate an accurate basic injection amount even when the engine is installed at an inclined angle or when the amount of air is high. The purpose of the present invention is to provide a stone jetting method and device.

The present invention provides an electronically controlled fuel injection method for an internal combustion engine in which a basic fuel injection amount is calculated according to an engine intake air amount and engine rotation speed detected by an air flow meter. By making the coefficient used when calculating the basic injection amount from the output intake air amount and Eisin rotation speed a function of the intake air amount,
The above objective has been achieved.

Further, an electronically controlled fuel injection device for an internal combustion engine in which the method is carried out includes an air flow meter that detects the intake air amount of the engine, and a rotation speed sensor that detects the engine rotation speed.
Using an injector that injects fuel into the engine and a mourning coefficient that is set as a function of the intake air amount, the basic injection amount is calculated from the intake air amount and engine rotation speed of the air flow meter 3 output, and the basic injection amount is calculated based on this. and an electronic control circuit that outputs a fuel injection signal to the injector.

Embodiments of the present invention will be described in detail below with reference to the drawings.

An embodiment of an electronically controlled fuel injection device employing the electronically controlled fuel injection method for an internal combustion engine according to the present invention is as shown in FIGS. 3 and 4, and is arranged in an intake passage 10 of an engine. The above-mentioned air flow meter 12 detects the intake air amount of the engine, the distributor 14 generates a pulse signal according to the engine rotation, the coolant temperature sensor 16 detects the engine coolant temperature, and the F70-
An intake air temperature sensor 18 disposed within the meter 12 that detects the engine intake air temperature, and a throttle position sensor that detects the opening degree of the nine throttle valves 20 disposed in the intake passage 10 and changes in the throttle valve opening degree. 22, a starter switch 24 that generates a starter signal during engine startup, an oxygen concentration sensor 28 that detects the oxygen concentration in the exhaust gas, which is disposed in the exhaust passage 26, and a rotation speed of the shaft of the transmission 30. The airflow meter output is determined using a vehicle speed sensor 32 for detecting the running speed of the vehicle, an injector 36 for injecting fuel into the intake manifold 34 of the engine, and a coefficient set as a function of the intake air amount. It is comprised of a digital electronic control circuit 38 that calculates a basic injection amount from the intake air amount and engine rotational speed and outputs a fuel injection signal determined based on this to the injector 36. Third
In the figure, 40 is an air cleaner, 42 is a surge tank, 44 is a spark plug, 46 is a catalyst connector (-),
In FIG. 4, 48 is a battery.

As shown in detail in FIG. 4, the digital electronic control circuit 38 is an analog circuit for converting analog signals output from the air flow meter 12 (including the intake air temperature sensor 18), the cooling water temperature sensor 16, and the battery 48 into digital signals. −
a digital converter 50; the distributor 14;
Throttle position sensor 22, starter switch 2
4. Input interface circuit 5 for inputting digital signals of the II elementary concentration sensor 28 and vehicle speed sensor 32 outputs
2, a central processing circuit 54, a read-only memory 56, a random access memory 58, and a central processing circuit 54 that converts the calculation result of $P into a fuel injection signal suitable for outputting to the injector 36. Output interface 7
It is composed of an ace circuit 60.

The operation will be explained below with reference to FIG. The digital electronic control circuit 38 calculates the basic injection time T using the following formula from the intake air amount Q of the air flow meter 12 output and the engine rotation speed NK calculated from the distributor 14 output.
Calculate P¥.

T, -ni-and ・・・・・・・・・・・・・・・・・・
(1) Here, K is a coefficient.

This coefficient was previously considered to be a constant, but
In this embodiment, for example, in order to prevent errors due to tilted mounting of the air flow meter, a function of the intake air amount Q as shown by the solid line A in FIG. 6 is used. Therefore, the intake air amount detection error of the air flow meter is corrected when calculating the basic injection time TP from the intake air amount and the engine rotational speed using equation (1) above. Note that the function value for the coefficient is not limited to that shown by the solid line A. For example, if the airflow meter is mounted horizontally and there is no error due to tilted mounting, the function value for the coefficient is not limited to that shown by the broken line B in Fig. 6. As shown, it is also possible to prevent over-richness when the air amount is high by making it small only when the air amount is high.

The basic injection time TP calculated in this way is compared with its upper limit value TP
! 1. If xt- is exceeded, it is limited by the upper limit value.

Furthermore, in accordance with the signals from each sensor, the basic injection time TP is corrected using the following equation to calculate the effective synchronous injection time by 1-.

Tx-Tp-f(A/F)f(wt)・,f(tam)
(1+f(Asg)+f(agw)+f(oTp)
1(1-f(as) l =...(2) Here, f(
A/F ) is the air-fuel ratio correction coefficient, f (wt, ) is the warm-up increase correction coefficient, f (THA ) is the intake air temperature correction coefficient, f
(*SE) is an increase correction coefficient after startup, f (AEW) is an acceleration increase correction coefficient during warm-up, f (oTp) is an overheat (output) increase coefficient, and f (R8) is a reduction coefficient.

As shown in the linear equation, the effective synchronous injection time rIK obtained in this way is the invalid injection time corresponding to the response delay time of the injector 36 when the battery voltage drops? By adding 'v, the synchronous injection time τ6 is calculated.

rs −rt +τv −°°−−°°°°°“°
-=<s+ A fuel injection signal corresponding to this synchronous injection time 5 is output to the injector 36, and the injector 36 is opened for the synchronous injection time 'i in synchronization with the engine rotation, and the fuel is injected into the intake manifold 34 of the engine. is injected.

As explained above, according to the present invention, even if the air flow meter is installed at an angle, or even when the air flow rate is high,
It is possible to calculate an accurate basic injection amount, and therefore, it has the excellent effect of accurately determining whether to perform appropriate fuel injection.

[Brief explanation of the drawing]

FIG. 1 is an exploded perspective view showing the configuration of an air flow meter used in an electronically controlled fuel injection device for an internal combustion engine, FIG. 2 is a sectional view of the same, and FIG. Embodiment of an electronically controlled fuel injection device employing an electronically controlled fuel injection method; FIG. 4 is a sectional view including a partial block diagram showing the installed internal combustion engine; A block diagram showing the component pipes, FIG. 5 is a flowchart showing the basic injection time calculation routine in the IitIg embodiment, and FIG. 6 shows the intake air amount and basic injection time calculation routine used in the embodiment. FIG. 4 is a diagram showing an example of the relationship between coefficients used when 12...Air flow meter, 14...Distributor, 36...Injector, 38...Digital electronic control circuit. Figure I Figure 2 Figure 2 Figure 0 Sonoputra 6

Claims (2)

[Claims] (1) In an electronically controlled fuel injection method for an internal combustion engine in which the basic fuel injection amount is calculated according to the engine intake air amount and engine rotation speed detected by an air flow meter, the air 70 - meter output is calculated. The coefficient used when calculating the basic injection amount from the intake air amount and the engine speed is made a function of the intake air amount, thereby correcting the intake air detection error of the air flow meter. An electronically controlled fuel injection method for internal combustion engines. (2) Using an air flow meter that detects the intake air amount of the engine, a rotation speed sensor that detects the engine speed, an injector that injects fuel into the engine, and a friend coefficient that is set as a function of the intake air amount, An internal combustion engine, characterized in that an electronic control circuit for calculating a basic injection amount from the intake air amount and engine rotation speed output from the air flow meter and outputting a fuel injection signal determined based on the basic injection amount to the injector is provided. The engine's electronically controlled fuel injection system.