JPS5828552A - Method and device for electronically controlled fuel injection to internal combustion engine - Google Patents

Abstract

PURPOSE:To easily attain a point of compatibility of the temperature of exhaust gas and the output of an engine, the injected fuel quantity of which is compensated depending on the engine condition etc., by setting the maximum value of the injected fuel quantity as a function of the rotational frequency of the engine and the temperature of its cooling water. CONSTITUTION:In the normal operation of an engine, an electronic control circuit 38 calculates a basic injection time Tp from the outputs of an air flow meter 12 and a distributor 14 and compensates the time Tp on the basis of the signals of sensors 16, 22 etc. to determine an effective synchronous injection time gammal. When the temperature of cooling water has exceeded 70 deg.C, the control circuit 38 reads out a table value gammamax stored in a read-only memory 56, on the basis of the output of the cooling water temperature sensor 16. When the effective synchronous injection time gammal is longer than the table value gammamax, the table value is used as the effective synchronous injection time. When the effective synchronous injection time gammal is longer than the upper limit gammau of the table value gammamax, the upper limit is used as the effective synchronous injection time. An ineffective injection time gammav determined at the time of the fall in the battery voltage is added to the effective synchronous injection time gammal to determine a synchronous injection time gammas to control injection valves 36.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electronically controlled furnace fuel injection method and device for an internal combustion engine, and in particular, to an electronically controlled furnace fuel injection method and device for an internal combustion engine. The present invention relates to an improvement in an electronically controlled fuel injection method and device for an internal combustion engine, which calculates a basic fuel injection amount and also corrects the fuel injection amount according to engine conditions.

One of the methods for supplying an air-fuel mixture at a predetermined air-fuel ratio to the combustion chamber of an internal combustion engine (referred to as an engine) is to use a so-called electronically controlled fuel injection device.

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 many such electronically controlled fuel injection devices, but in recent years, especially in VC, digital electronically controlled fuel injection devices in which the electronic control circuit has been digitalized have been developed. In such an electronically controlled fuel injection bag NVc, the calculation is usually based on the engine intake air amount detected using an air flow meter, etc., and the engine rotation speed detected from the engine rotation signal input from the distributor. Synchronized injection, in which the basic fuel injection amount is corrected based on good signals input from sensors installed in each part of the engine according to the engine status, etc., and the fuel is injected 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 calculated using the intake air amount from the air flow meter and the rotation signal from the distributor, and the signal from each senna, It is determined by multiplying the injection time by a correction coefficient to correct the injection time according to the engine condition MIC at that time, such as when cold or accelerating, and further adding the invalid injection time to correct the injector operation delay due to voltage fluctuation. ing. The basic injection time is, for example, in order to improve engine startability,
When starting the engine, the starting privilege is corrected by setting it as a predetermined time regardless of the intake air amount and engine speed.
In addition, in order to stabilize the engine rotation immediately after starting, the amount is increased for a certain period of time after starting the engine, and the amount is corrected after starting.Furthermore, when the intake air temperature is low, the air density increases (and the air amount decreases). In order to prevent deviations in the air-fuel ratio caused by an increase in air-fuel ratio, the intake air temperature is corrected by increasing the amount when the intake air temperature is low.Also, to ensure drivability in cold conditions, the amount is increased when the cooling water temperature is low. In addition, in order to prevent sluggishness immediately after acceleration and improve acceleration performance, the amount is increased for a certain period of time immediately after acceleration to compensate for the increase in the amount of acceleration during warm-up. In order to increase the engine output at high load times, the output increase is corrected by increasing the throttle valve opening at high loads, e.g. 600 or more. In order to keep the air-fuel ratio close to In order to reduce fuel consumption, fuel injection is stopped and fuel is cut during engine braking or when the vehicle speed exceeds a specified maximum speed.

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, traditional electronically controlled fuel injection devices,%
Detection of intake air amount 1. It was fixed to a rotatable shaft 7) 12a as shown in FIGS. 1 and 2. A measuring plate 12b inserted into the airway, a return spring 12e that biases the measuring plate 12b in the direction of closing the intake passage, and a potentiometer 12d disposed at one end of the shirt 12m. An air flow meter that detects and outputs 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 12eK, using a potentiometer 12d. 12, the amount of intake air is very large (at high speeds or under high load, the measuring plate 12b opens too much due to the pulsation of the intake air, resulting in an excessive amount of intake air in the engine). In the figure, 12e is a convention plate.In order to prevent the above-mentioned drawbacks, the air 70-meter is Efforts have been made to install a full load stopper to prevent the measuring plate from opening too much, or to set the maximum value fmax of the fuel injection amount, but these methods are not always effective. In particular, in the latter method, the maximum value τmax was
As shown in the double-dot chain @IK in the figure, if the engine speed is constant regardless of the engine speed, the control of the fuel injection amount becomes almost ineffective when the engine speed is high, resulting in over-richness and the engine output. Let's lower it. On the other hand, the maximum value 'm
&X, one-point chain 11 in Figure 3! It is conceivable to change the speed in two stages according to the engine speed, as shown by B or the broken line CK, but in order to obtain sufficient output at high engine speeds, as shown by the dashed line B, the maximum If the value rmaw is set to a relatively small value, the restriction by τmax ic becomes too effective in the engine mid-speed range, and the air-fuel ratio becomes relatively lean, as shown by the dashed line BK in Figure 4. Exhaust gas temperature may rise. In addition, as shown by the broken line CK in Figure 3, if the maximum value τma at high engine speeds is set to a relatively large value in order to prevent the exhaust gas temperature from rising in the middle engine speed range, overflow occurs at high engine speeds. The problem was that the engine became rich and the engine output decreased. Furthermore, regardless of the engine cooling water temperature, the maximum value fm
If LX was decreased in stages, there was a possibility that sufficient increase correction would not be made when the engine coolant temperature was low.

The present invention was made in order to eliminate the above-mentioned conventional drawbacks, and it is possible to easily achieve a balance between exhaust gas temperature 1 and engine output, and moreover, the fuel injection control suitable for the engine cooling water temperature is effective. An object of the present invention is to provide an electronically controlled fuel injection method and device for an internal combustion engine.

The present invention provides an electronically controlled fuel injection system for an internal combustion engine that calculates a basic fuel injection amount according to the intake air amount and engine speed of the engine, and also corrects the fuel injection it according to the engine condition etc. In the method, the maximum value of the fuel injection amount is set as a function of the engine speed and the engine cooling water temperature, thereby achieving the above object.

Further, the maximum value of the fuel injection amount is constant regardless of the engine speed when the engine cooling water temperature is low, and is approximately linear when the engine speed is high depending on Kq when the engine cooling water temperature is high and the engine speed. It was designed to decrease to

Furthermore, an electronically controlled fuel injection device for an internal combustion engine in which the method is carried out includes an intake air amount sensor that detects the intake air amount of the engine, a rotation speed sensor that detects the engine rotation speed, and an engine cooling water temperature. A cooling water temperature sensor, an intake air temperature sensor that detects the engine intake air temperature, a throttle valve Nil sensor that detects throttle valve opening 1 and a change in throttle valve opening, and a starting sensor that detects that the engine is starting. , an oxygen chain sensor that detects the presence of oxygen in exhaust gas, a vehicle speed sensor that detects the vehicle's running speed, an injector that injects fuel into the engine, and In addition to calculating the basic fuel injection time, the fuel injection time is corrected according to the engine condition, etc., and the corrected fuel injection time is then set as a function of the engine speed and the engine cooling water temperature. an electronic control circuit that outputs a fuel injection signal to the injector while limiting the time so as not to exceed a maximum value;
It was constructed using

Embodiments of the present invention will be described 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. 5 and 6, and is arranged in an intake passage 10 of an engine. The air flow meter 12 as described above 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 air flow meter 12 includes: An intake air temperature sensor 18 that detects the engine intake air temperature, a throttle position sensor 22 that detects the opening of the throttle valve 20 disposed in the intake passage 10 and changes in the throttle valve opening, and the engine. The starter switch 24 generates a starter signal during startup, the oxygen concentration sensor 28 is installed in the exhaust passage 26 and detects the oxygen concentration in the exhaust gas, and the rotation speed of the shaft of the transmission 30 determines whether the vehicle is running. A vehicle speed sensor 32 for detecting the speed, an injector 36 for injecting the Kffi fuel in the intake manifold 34 of the engine, and calculating the basic fuel injection time according to the intake air amount and engine speed of the engine, Correcting the fuel injection time according to engine conditions etc.,
Furthermore, a digital electronic device outputs a fuel injection signal to the injector 36 by limiting the corrected fuel injection time so that it does not exceed a maximum value τmax of the fuel injection time set as a function of engine speed and engine cooling water temperature. It is composed of a control circuit 38. F, In figure 5, 4
0 is an air cleaner, 42 is a surge tank, 44 is a spark plug, 46 is a catalytic converter, and in FIG. 6, 48 is a battery.

As shown in detail in FIG. 6, the digital electronic control circuit 38 includes an air flow meter 12 (including an intake air temperature sensor 18), a cooling water temperature sensor 16. and an analog-to-digital signal generator 50 for converting the analog signal output from the battery 48 into a digital signal, and the distributor 1
4. An input interface circuit 52 for inputting digital signals output from the throttle position sensor 22, starter switch 24, oxygen concentration sensor 28, and vehicle speed sensor 32, a central processing circuit 54, a read-only memory 56, and a random access memory. 58, and an output interface circuit 60 that converts the calculation result in the central processing circuit 54K into a fuel injection signal suitable for outputting to the injector 36.

The operation will be explained below with reference to FIG. First, the basic injection time Tp is calculated from the digital electronic control circuit 38Fi, the intake air amount Q of the air flow meter 12 output, and the engine rotational speed NK calculated from the distributor 14 output using the following equation.

Here K is a coefficient.

Furthermore, the effective synchronous injection time f is calculated by correcting the basic injection time Tp using the following equation according to the signals from each sensor.

' + =Tp-f (A'?) ・f (WL)
・f (THA) ' (1+f (ASE),
.

d(ffl)+f(OTP))(1-f(R8))-・
...(2) In Komu, f (A/F) is the air-fuel ratio correction coefficient -
f(WL) is a warm-up increase correction coefficient, f(THA) is an intake air temperature correction coefficient, and f(ASE) is a post-start increase correction coefficient.

f (AEW) is acceleration increase correction coefficient during warm-up, f (OTP)
is an overheat (output) increase coefficient, and f(R8) is a decrease coefficient.

Next, in accordance with the output of the cooling water temperature sensor 16, when the cooling water temperature is high, for example exceeding 70°C, a table as shown in the solid line in FIG. 3, which is stored in the read-only menu 56, is displayed. Read the value, this is t'max
shall be. Comparing this -aX and the above v1, τ1 becomes fmB
If it exceeds xt, it is read from the table.
Let mJLX be τ. Furthermore, τ obtained in this way is compared with the upper limit value τ6 of τmax, and τ1 is ru
If it exceeds l, this g is taken as V. or,
At low temperatures when the cooling water temperature is 70°C or less, the upper limit of τm□.

If τ9I exceeds fut-, then
τ5 is assumed to be .

To the effective synchronous injection time f1 obtained in this way, as shown in the following equation, by adding an invalid injection time τ7 corresponding to the response delay time of the injector 36 when the battery voltage drops and the injector 36 is in good condition, the same injection time τ, Calculate.

'@＝'＊＋”v ・・・・・・・・・・・・(3)
A fuel injection signal corresponding to the synchronous injection times r, K is output to the injector 36, and the injector 36 is opened for the synchronous injection time τS in synchronization with the engine rotation, and fuel is injected into the intake manifold 34 of the engine. .

In the above embodiment, the engine cooling water temperature was 70°C.
At a low temperature below [ti, τmax is made equal to τU,
I tried to keep it constant regardless of the engine speed, but
Of course, when the engine cooling water temperature is low, a different table may be used than when it is high.

As explained above, according to the present invention, it is possible to achieve both exhaust gas temperature and engine output, and moreover, when the engine cooling water temperature is low, 'max is unnecessarily limited.
7, it has the excellent effect of performing a good fuel increase correction.

[Brief explanation of drawings]

gt diagram is an exploded perspective view showing the configuration of an air meter used in a conventional electronically controlled fuel injection system.
FIG. 2 is a sectional view, FIG. 3 is a diagram showing the relationship between the engine speed and the maximum fuel injection amount in the conventional example and the embodiment of the present invention, and FIG. 4 is a diagram showing the relationship between the engine speed and the maximum fuel injection amount. FIG. 5 is a diagram showing the vertical relationship between the temperature and the exhaust gas temperature, and FIG. FIG. 6 is a block diagram showing the circuit configuration of the embodiment, and FIG. 7 is a flowchart showing the fuel injection time calculation routine in the embodiment. be. 12... Air flow meter, 14... Distributor, 16... Cooling water temperature sensor, 18... Intake air temperature sensor, 22... Throttle position sensor,
24...Starter switch, 28...Oxygen m degree sensor, 32...Vehicle speed sensor, 36...Injector,
38...Digital electronic control circuit. Agent Takaya Ron (and 1 other person): Nal Figure 2 Figure 2 庙弗7 Figure ↑ Se

Claims (3)

[Claims] (1) An electronically controlled fuel injection method for an internal combustion engine in which a basic fuel injection amount is calculated according to the engine intake air amount and engine rotation speed, and the fuel injection amount is corrected according to the engine condition, etc. An electronically controlled fuel injection method for an internal combustion engine, characterized in that the maximum value of the fuel injection amount is set as a function of engine speed and engine cooling water temperature. (2) When the engine cooling water temperature is low, the maximum value of the fuel injection amount is constant regardless of the engine rotation speed, and when the engine cooling water temperature is iI6 temperature, the maximum value of the fuel injection amount is approximately constant depending on the engine rotation speed when the engine rotation speed is high. Claim 1x) 4rs: Electronically controlled fuel injection method for an internal combustion engine as described in claim 1x) 4rs, which is linearly decreasing. (3) An intake air amount sensor that detects the intake air amount of the engine, a frequency sensor that detects the engine rotation speed, a cooling water temperature sensor that detects the engine cooling water temperature, and an intake air temperature that detects the engine intake air temperature. A sensor, a throttle valve 141 that detects the throttle valve opening degree and a change in the throttle valve opening degree [Sensor, a starting sensor that detects that the engine is being started,
There is an oxygen concentration sensor that detects the oxygen concentration in exhaust gas, a vehicle speed sensor that detects the running speed of the vehicle, and an injector that injects fuel into the engine. In addition to calculating the fuel injection time, the fuel injection time is corrected according to the engine condition, etc., and the corrected fuel injection time is the maximum fuel injection time set as a function of the engine rotation speed and the engine cooling water temperature. 1. An electronically controlled fuel injection device for an internal combustion engine, comprising: an electronic control circuit that outputs a fuel injection signal to the injector while limiting the fuel injection signal so as not to exceed a predetermined value.