JPS5828537A - Electronically controlled fuel injection process and equipment in internal combustion engine - Google Patents

Abstract

PURPOSE:To sharply improve starting ability in the engine in such a way that fuel injection time when starting the engine is compensated in response to inhaled air temperature in the engine and to battery voltage. CONSTITUTION:During ordinary operation, an electronic control circuit 38 computes the reference injection time through each output from an air-flow meter 12 and a distributor 14. On another hand, at the time of being in the condition of starting the engine, the reference injection time for starting in response to the cooling water temperature is read out from the determined table which is memorized in ROM56, compensating factor in response to inhaled air temperature, and the effective injection time tau1 is computed by multiplying those values. Besides, an injection valve 36 is controlled in such a way that the fact that whether or not it is the synchronous injection time, the unavailable injection time tauv in responce to battery voltage is read out through the determined table in the ROM 56, and injection valve 36 is controlled by computing the synchronous fuel injection time taus using the added value of the both time tau1 and GAMMAs.

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 particularly suitable for use in an internal combustion engine for an automobile.
The basic fuel injection time is calculated according to the intake air amount and engine speed of the engine, and the fuel injection time is corrected according to the engine condition. Concerning improvements to equipment.

One method of supplying an air-fuel mixture of a predetermined air-fuel ratio to the combustion chamber of an internal combustion engine II (referred to as an engine) uses a so-called electronically controlled fuel injection device.

CRT is an injector for injecting fuel into the engine, such as the engine's intake! By arranging several or one engine cylinder in the nitrogen fold or throttle body and controlling the valve opening time of the injector according to the operating state of the engine, a mixture with a predetermined O air-fuel ratio is supplied to the engine combustion chamber. It is something to do. There are various types of such electronically controlled fuel injection devices, but in recent years, electronically controlled fuel injection devices such as this one have been particularly popular, and the electronically controlled fuel injection device, in which the electronic control circuit has been digitized, has been developed. In the device, the basic fuel is usually calculated according to the intake air amount of the engine detected using an air meter, etc., and the engine speed detected from the engine rotation signal input from the distributor. The injection amount is corrected by signals input from sensors installed in each part of the engine according to the engine status, etc., and synchronous injection is performed in synchronization with the engine rotation and always injects at the same crank position, and synchronous injection is used to improve startability or immediately after acceleration. In order to improve responsiveness, in addition to normal synchronous injection, asynchronous injection is performed in which a predetermined amount of injection is performed only immediately after a signal from the Senna is received according to the driving condition. The synchronous injection time when the injector fi is open is, for example, based on the basic injection time calculated using the intake air amount from the air meter and the rotation signal from the distributor, and the signal from each sensor.
Multiplying the injection time by a ninth correction coefficient that corrects the injection time according to the engine state at zero, such as when cold or accelerating, and further adding an invalid injection time to correct for injector operation delays due to voltage fluctuations. For example, in order to improve engine startability, the basic injection time determined by 0 is corrected at the time of engine startup by setting it to a predetermined time regardless of the intake air amount and engine rotational speed at the time of engine startup,
In addition, to stabilize the engine rotation immediately after starting, the amount is increased for a certain period of time after the engine starts, and the amount is corrected after starting, and when the intake air temperature is low, the air density changes and the air amount increases. Rounding to prevent deviations in the air-fuel ratio due to an increase in intake air temperature, correction of the intake air temperature by increasing the intake air temperature when the intake air temperature is low, and rounding to ensure drivability in cold conditions, when the cooling water temperature is low. By increasing the amount, the amount is increased to compensate for the warm-up amount.Furthermore, in order to prevent lagging immediately after acceleration and improve acceleration performance, the amount is increased for a certain period of time immediately after acceleration to compensate for the amount of increase in the amount for warm-up acceleration. is,
In addition, in order to increase the engine output during high loads, the output increase is corrected by increasing the throttle valve opening at high loads, for example, 60 degrees or more, and furthermore, the air-fuel ratio of the mixture is adjusted to a predetermined air-fuel ratio, such as the stoichiometric air-fuel ratio. In order to maintain the air-fuel ratio close to the air-fuel ratio, the air-fuel ratio is feedback corrected by carbonizing the increase ratio according to the oxygen concentration in the exhaust gas. Also, to prevent overheating of the catalytic converter and save fuel consumption, or to force the vehicle speed To hold down the target, during carrot brake, or
When the vehicle speed exceeds a specified maximum speed, fuel injection is stopped to perform a fuel 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 starting injection in such electronically controlled fuel injection systems, the engine cooling water temperature is controlled by the engine cooling water temperature because the starting injection is carried out at a constant basic injection time regardless of the intake air amount and engine speed. , depending on the intake air temperature or battery voltage, it may not be possible to perform a good start. In other words, if the engine coolant temperature or the intake air temperature is low, the above basic injection time at startup may not be enough. In some cases, starting performance may not be obtained, or if the battery voltage drops, the so-called invalidation occurs from the time the fuel injection signal is given to the injector until the injector actually opens and fuel injection starts. There were cases where the injection time became long and the effective injection time required at startup could not be obtained.The present invention was made to solve the above-mentioned conventional drawbacks, and it is possible to reduce the An object of the present invention is to provide an electronically controlled fuel injection method and device for an internal combustion engine in which engine startability does not deteriorate even when the engine startability decreases.

The present invention provides an electronically controlled fuel injection system for an internal combustion engine that calculates a basic fuel injection time according to the intake air amount and engine speed of the engine, and also corrects the fuel injection time according to the engine condition. In the method, the above object is achieved by correcting the fuel injection time at the time of engine startup according to the engine intake air temperature and the battery voltage. Also, the fuel injection time at the time of engine startup, It is calculated by multiplying the basic injection time at startup by a correction coefficient according to the engine intake air temperature, and then adding the invalid injection time according to the battery voltage. An electronically controlled fuel injection system for an internal combustion engine is equipped with an intake air amount sensor that detects the intake air amount of the engine, a rotation speed sensor that detects the engine speed, a coolant temperature sensor that detects the engine coolant temperature, and an engine. An intake air temperature sensor that detects the intake air temperature, a starting sensor that detects when the engine is starting, an injector that injects fuel into the engine, and a basic fuel sensor that detects the intake air temperature and the rotational speed of the engine. In addition to calculating the injection time, the fuel injection time at engine startup is calculated by multiplying the basic injection time at startup by nine correction coefficients according to the engine intake air temperature, and further adding the invalid injection time according to the battery voltage. 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. 1 and 2, and is arranged in an intake passage 10 of an engine. An airflow meter 12 that detects the intake air amount of the engine, a distributor 14 that generates a nine-pulse signal according to engine rotation, a cooling water temperature sensor 16 that detects the engine cooling water temperature, and an airflow meter 12 that detects the intake air amount of the engine. An intake air temperature center t18 arranged to detect the engine intake air temperature, and a throttle valve 20 arranged in the intake passage 10.
a throttle position sensor 22 that detects the opening of the throttle valve and changes in the opening of the throttle valve, a starter switch 24 that generates a starter signal during engine startup, and a starter switch 24 that detects the oxygen concentration in the exhaust gas, which is arranged in the exhaust passage 26. The ninth military speed sensor detects the running speed of the vehicle from the oxygen concentration sensor 28 and the rotation speed of the shaft of the speed gear 30. 82 and an injector 36 for injecting fuel into the intake manifold 34 of the engine.
Then, the basic fuel injection time is calculated according to the intake air volume and engine speed, and the fuel injection time at engine startup is changed to the basic injection time at startup by a correction coefficient according to the engine intake air temperature. Multiplying and further adding the invalid injection time according to the battery voltage,
In Figure 1, 40 is an air cleaner, 42 is a surge tank, and 4 is a digital electronic control circuit 38 that outputs a fuel injection signal to the injector.
4 is a spark plug, 46 is a catalyst controller 2 (-ta is sb, second
In the figure, 48 is a battery.

The digital electronic control circuit 38 has an air 70-meter 12 (@ large air temperature sensor 18)
), a cooling water temperature sensor 16, an analog-to-digital converter sO for converting the analog signal output from the battery 48 into a digital signal, the distributor 14, the throttle position sensor 22, the starter switch 24, and the oxygen A rounded input interface circuit 52 that inputs the digital signals output from the concentration sensor 28 and the vehicle speed sensor 32, a central processing circuit 54, a read-only memory 56, a random access memory 58, and the calculation results in the central processing circuit s4. An output interface circuit 60 converts the fuel injection signal into a fuel injection signal suitable for output to the injector 36.

The operation will be explained below. First, in a normal state after the engine is started, where the engine speed is, for example, SOO- or higher, the digital electronic control circuit 38 controls the air 70-meter 1
The basic injection time T is calculated from the intake air amount Q of the 2 outputs and the DI jC) 9 views and 14 outputs, depending on the engine rotation speed N, using the following formula.

Calculate.

Here K is a coefficient.

Furthermore, by correcting the basic injection time TP using the following formula according to the signals from each sensor, the effective synchronous injection time T! Calculate.

Ding 1=TP @/(A/F)-/(WL)・/(THA
)・(1+/(A8B)+/(ANW)+/(OTP)
)(1-/(R8))...old...(2
) Here, / (A/F ) is the air-fuel ratio correction coefficient, / (W
L) is - machine increase correction coefficient, /(THA) is intake air temperature correction coefficient, /(A8)]) is start-start increase correction coefficient, /(person nw)q warm-up acceleration increase correction coefficient, /(OTP ) is the overheat (output) increase coefficient, /(R8) is the decrease coefficient.◎ On the other hand, when the engine speed is, for example, less than SOO*, the digital electronic control Read-only memory 56 of circuit 38
The basic injection time τ8TAt at starting according to the engine cooling water temperature is read out from a table showing the relationship between the engine cooling water temperature and the starting basic injection time rs'rAo as shown in FIG. Next, the engine intake air temperature and the engine intake air temperature correction coefficient/
Read out the correction coefficient/(THA) according to the engine intake air temperature from the table showing the relationship between Therefore, the effective injection time txt is calculated.

Furthermore, as shown in Fig. 6, it is determined whether or not it is time for synchronous injection based on the state of the injection flag, and if it is the time for synchronous injection, the information in Fig. IJ7 stored in advance in read-only memory s6 is determined. As shown in the table, the invalid injection time τ corresponding to the battery voltage at that time is read out from the table showing the relationship between the battery voltage B and the invalid injection time τV. Next, as shown in the following equation, the synchronous fuel injection time 1B is calculated by adding this invalid injection time τV to the effective injection time TI obtained through the above process.

τ1=τ1+TV ・・・・・・・・・・・・・・・(
3) The fuel injection signal corresponding to this synchronous injection time raK is
The fuel is output to the injector 36, the injector 36 is engaged for a synchronous injection time τS in synchronization with the engine rotation, and fuel is injected into the intake manifold 34 of the engine.

In the end, in this embodiment, the RTm at the time of fuel injection at startup
The basic injection time at startup τ8T is determined according to the engine cooling water temperature, the correction coefficient 7/(THA) is determined according to the engine intake air temperature, and the invalid injection time TV is determined according to the battery voltage BK. , is calculated using the following formula.

T11=τ8TAx/(THA)+TV・・・・・・・
・・・・・・・・・(4) In this way, not only the fuel injection time after engine start, but also the fuel injection time at engine start are corrected according to the engine intake air temperature and battery voltage. This greatly improves low-temperature restartability and startability using a discharged battery.

As described above, according to the present invention, engine startability does not deteriorate even when the engine intake air temperature or battery voltage decreases.1 Therefore, engine startability can be greatly improved. It has the excellent effect of reducing

[Brief explanation of the drawing]

FIG. 1 includes a partial diagram showing nine internal combustion engines in which 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 disposed. 112m is a block diagram showing the circuit configuration of the embodiment, FIG. 3 is a flowchart showing the fuel injection time calculation routine in the embodiment 1, and FIG. Figure 1g5 is a striped diagram showing the relationship between engine cooling water temperature and basic injection time at startup, and Figure 1g5 is a striped diagram showing the relationship between engine intake air temperature and correction coefficient, and Figure jlI6 is a striped diagram showing the relationship between engine cooling water temperature and basic injection time at startup. Flowchart showing the Kero fuel injection processing routine, #! Figure 7 is a diagram showing the relationship between battery voltage and invalid injection time, which is used in the fuel injection processing routine. ◎12... Air flow meter, 14... Distributor, 16... Cooling water temperature sensor 1 18...Intake air amount sensor, 24...Starter switch, 36...Injector, 38...Digital electronic control circuit, 48...Batch 90's salt input Takaya Ron (and others) 1 person) Fig. 3 Fig. 6 Fig. 44 Fig. Engines running out of water Fig. 5 Engine intake air transition LB

Claims (1)

[Scope of Claims] a) An electronic system for an internal combustion engine that calculates a basic fuel injection time according to an engine intake air amount and engine rotation speed, and corrects the fuel injection time according to engine conditions, etc. An electronically controlled fuel injection method for an internal combustion engine, characterized in that the fuel injection time at engine startup is corrected in accordance with the engine intake air temperature and the exhaust voltage. (2) The fuel injection time at engine startup is determined by multiplying the basic injection time at startup by a correction coefficient depending on the engine intake air temperature, and then adding the invalid injection time depending on the battery voltage. An electronically controlled fuel injection method for an internal combustion engine according to claim 1. (Control) An intake air amount sensor that detects the intake air amount of the engine, a rotation speed sensor that detects the engine speed, a cooling water temperature sensor that detects the engine coolant temperature, and an intake air temperature sensor that detects the engine intake air temperature. , a starting sensor that detects when the engine is starting, an injector that injects fuel into the engine, and a basic fuel injection time that calculates the basic fuel injection time according to the engine intake air amount and engine speed. The fuel injection time of the injector is determined by multiplying the basic injection time at startup by nine correction coefficients according to the engine intake air temperature, and further adding the invalid injection time according to the battery voltage, and the fuel injection signal is determined by An electronically controlled fuel injection device for an internal combustion engine, characterized in that it is equipped with an electronic control circuit that outputs an output to