JPH0223698B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an injection amount correction method for an electronic fuel injection control device for an internal combustion engine.

In an electronic fuel injection control device for an internal combustion engine, the basic amount of fuel injection is determined using either the intake pipe internal pressure downstream of a throttle valve installed in the engine's intake pipe or the throttle valve opening and the rotational speed. There is. A method for determining such a basic injection amount is to use a matrix memory (P _B - Ne map) using the engine speed Ne and the intake pipe internal pressure P _B downstream of the throttle valve as parameters in a relatively low load region of the engine. Also, in a relatively high load region, engine speed Ne and throttle valve opening θth
Matrix memory (θth
There is a hybrid method that uses the -Ne map) to determine the basic fuel injection amount Ti.

Furthermore, in turbocharged engines,
Intake pipe internal pressure (intake pressure) on the upstream side of the compressor P ₁
and the intake air temperature T ₁ and the intake pipe internal pressure on the downstream side of the compressor, that is, the supercharged intake air pressure (supercharging pressure) P ₂ at the intermediate point between the compressor outlet and the throttle valve, and these detected values P ₁ , T ₁ ,
Determine the intake air density correction coefficient γ _A using P ₂ as a parameter, and use the correction coefficient γ _A to adjust the basic fuel injection amount Ti.
The fuel injection amount is corrected in accordance with changes in intake air temperature and pressure, that is, density due to changes in operating conditions.

However, the boost pressure sensor that detects the intake pipe internal pressure _P2 on the downstream side of the compressor for intake air density correction is required to have high detection accuracy and quick response. As described above, a diaphragm type semiconductor pressure sensor is used as a pressure sensor, but such a pressure sensor is expensive, and the system accordingly becomes expensive.

The present invention has been made in view of the above-mentioned points, and it is possible to perform necessary intake air density correction by simulating the intake pipe internal pressure _P2 downstream of the compressor using other parameters. The purpose of this invention is to provide a system that does not require a pressure sensor for _P2 detection. In order to achieve this object, the present invention has developed a system for adjusting the rotational speed Ne of a fuel injection engine having an intake pipe in which a compressor such as a turbocharger, an air cleaner, and an intake port of the engine are connected, and a throttle valve downstream of a throttle valve provided in the intake pipe. An electronic method for an internal combustion engine that determines the basic fuel injection amount based on parameters such as intake pipe internal pressure P _B or throttle valve opening θth, and corrects the basic fuel injection amount by determining an intake air density correction coefficient according to the operating state of the engine. In the injection amount correction method of the fuel injection control device, the intake air density is corrected as a function of the parameters of the intake pipe internal pressure P ₁ and its intake air temperature T ₁ on the upstream side of the compressor, and the intake pipe internal pressure P _B downstream of the throttle valve. The present invention provides an injection amount correction method for an electronic fuel injection control device for an internal combustion engine, which calculates a coefficient.

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

First, the principle of the fuel injection amount correction method of the present invention will be explained.

The intake air density correction coefficient γ _A for correcting the basic heating charge injection amount Ti is expressed by the following equation.

γ _A = P ₂ / P ₀ × T ₀ / T ₂ ………(1) Here, the value P ₀ is standard atmospheric pressure (760mmHg), T ₀ is standard temperature (25℃), and P ₂ is the downstream side of the compressor. T2 represents the intake pipe internal pressure, and _T2 represents the intake air temperature downstream of the compressor. This intake air temperature T ₂ changes greatly and quickly due to changes in engine operating conditions, so in terms of detection accuracy and responsiveness, direct detection with a temperature sensor requires the use of an expensive temperature sensor device, so it is necessary to use calculations. It is being calculated.

The intake pipe internal pressure downstream of the engine throttle valve and the intake pipe internal pressure upstream of the compressor are respectively P _B , P ₁ ,
Let those intake air temperatures be T _B and T ₁ respectively (T _B /
The relationship between T ₁ ) and (P _B /P ₁ ) is approximated by a linear function as shown in FIG. 1, and can be expressed by the following relational expression.

T _B ／Ti＝ai(P _B ／P ₁ )＋bi ……(2) (ai and bi are constants) Therefore, T _B ＝T ₁ {ai(P _B ／P ₁ )＋bi} ……( 3) In addition, the intake air density correction coefficient γ _A is expressed by the following formula.

γ _A =P ₂ /P ₀ ×T ₀ /T ₂ = (P _B /P ₀ ) ^n-1/n ×T ₀ /T _B ......
...(4) (n is a polytropic index) Therefore, by substituting the above equation (3) into this equation (4), the coefficient γ _A is given by the following equation.

γ _A = (P _B /P ₀ ) ^n-1/n ×T ₀ /T _B = (P _B /P ₀
)) ^n-1/n ×T ₀ /T ₁ ×1/ai (P _B /P ₁ ) + bi……(5) In this formula (4), the values P ₀ and T ₀ are constants as mentioned above. The intake pipe internal pressure P ₁ is detected by a pressure sensor, and the intake air temperature T ₁ is detected by a temperature sensor. Therefore, according to the above equation, it is possible to approximate the value P ₂ by P _B , and it is possible to obtain the correction coefficient γ _A without detecting the intake pipe internal pressure P ₂ .

FIG. 2 is a block diagram showing an embodiment of a two-cylinder engine according to the present invention. In the figure, numerals 1 and 2 indicate first and second variable reluctance shaft rotation sensors, respectively.
is for detecting the camshaft CA of the engine E shown in FIG. 3 at the reference position, and in this embodiment, they are arranged so as to output pulses having a phase difference of 180 degrees from each other. These sensors 1 and 2 are connected to the input sides of waveform shaping circuits 3 and 4, respectively, and the output side of the latter is connected to the input sides of an engine revolution counter 6 and injection time counters 31 and 32. The clock oscillation circuit consists of counters 6, 23, 31, 32.
and the input side of the analog switch 11, and supplies the counters 6, 23, 31, and 32 with the clock pulse CP, and the analog switch 11 with the control pulse φ.

FIG. 3 is a schematic diagram of a turbocharged engine according to the present invention, and the exhaust gas of engine E is discharged from the exhaust pipe.
It is supplied to the turbine T of the turbocharger TB through Ex, and after driving this turbine T, the muffler M
The air discharged from the air cleaner AC is compressed by a compressor C directly connected to the turbine T, and is supplied to the intake valve side of the engine E through the intake pipe In. Further, the symbol R indicates a resonance chamber, and the symbol S indicates a surge tank.

The pressure sensor 7 detects the pressure P _B on the downstream side of the throttle valve TL as shown in FIG. 3 in the intake pipe of the engine, and is composed of, for example, a diaphragm and a semiconductor. The throttle valve opening sensor 8 detects the opening θth of the throttle valve TL disposed in the intake pipe of the engine, and is composed of, for example, a potentiometer. The temperature sensor 9 detects the intake air temperature _T1 at the inlet of the compressor with turbocharger. The pressure sensor 10 detects the intake pipe internal pressure _P1 on the upstream side of the compressor, that is, at the inlet of the compressor C. These pressure sensor 7, throttle valve opening sensor 8, temperature sensor 9, and pressure sensor 10 are connected to each input side of an analog switch 11, and the output side of the analog switch 11 is connected to an analog-to-digital converter (hereinafter referred to as A-D). 12 (referred to as a converter).

The output side of the A-D converter 12 includes a comparison circuit 14 of the basic fuel injection amount calculation circuit 13, a basic fuel injection amount storage circuit (P _B -Ne map) 15, and a basic fuel injection amount storage circuit (θth-Ne map). 16 and the intake air density correction coefficient storage circuit 26, respectively. The output side of the engine revolution counter 6 is connected to each input side of the basic fuel injection amount storage circuits 15 and 16.

The output sides of the basic fuel injection amount storage circuits 15 and 16 are connected to one input side of the multiplication circuit 30, and the output side of the intake air density correction coefficient storage circuit 26 is connected to the other input side, and the output side is connected to an injection time counter. 3
It is connected to the input side of 1 and 32. The output sides of these counters 31 and 32 are connected to the input sides of injection valve drive circuits 33 and 34, respectively, and the output sides of the latter are connected to fuel injection valves 35 and 36, respectively.

Next, the operation of the configuration shown in FIG. 2 will be explained.

The first and second shaft rotation sensors 1 and 2 are the camshaft CA
A reference position is detected, and pulses having a phase difference of 180 degrees or more are supplied to waveform shaping circuits 3 and 4, respectively.
There, the waveform is shaped and output as pulses Pa and Pb. The counter 6 receives clock pulses input from the clock oscillation circuit 5 between the time when the pulse Pa is input and the time when the pulse Pb is input.
The period between the reference positions of the shaft rotation sensors 1 and 2 is measured by counting CP, and a binary code signal proportional to the reciprocal of the period, that is, the engine rotation speed Ne is output.

Intake pipe internal pressure downstream of engine throttle valve
P _B is determined by pressure sensor 7 as throttle valve opening θth
is detected by the throttle valve opening sensor 8, the intake air temperature _T1 on the upstream side of the compressor C is detected by the temperature sensor 9, the intake pipe internal pressure _P1 on the upstream side of the compressor is detected by the pressure sensor 10, and each detected analog signal are sequentially A-D through an analog switch 11 which is switched by a control pulse φ applied from a clock oscillation circuit 5 at a predetermined timing.
The signals are sent to a converter 12, where they are converted into corresponding binary code signals, and the necessary signals are output to each circuit.

The comparison circuit 14 compares the A-D converted signal corresponding to the throttle valve opening θth with the set value θth ₁ ,
If θth<θth ₁ , the basic fuel injection amount memory circuit 1
5, and when θth>θth ₁ , the basic fuel injection amount storage circuit 16 is selected. Basic fuel injection amount memory circuit 1
5 is the engine rotation speed output from counter 6
A signal corresponding to Ne and a signal corresponding to the intake pipe internal pressure P _{B on the downstream side of the throttle valve output from the A-D converter 12 are input, and the intake pipe internal pressure P B on} the downstream side of the throttle valve and the engine speed are set in advance. A binary code signal corresponding to the basic fuel injection amount Ti stored as a function of the number Ne is output. The basic fuel injection amount storage circuit 16 inputs a signal corresponding to the engine rotation speed Ne output from the counter 6 and a signal corresponding to the throttle valve opening θth output from the A-D converter 12, and A binary code signal corresponding to the basic fuel injection amount Ti stored as a function of the valve opening θth and the engine speed Ne is output. That is, when θth<θth ₁ , the basic fuel injection amount storage circuit 15 reads θth>θth _1.
At this time, the basic fuel injection amount storage circuit 16 outputs a binary code signal corresponding to the required basic fuel injection amount Ti.

The intake air density correction coefficient storage circuit 26 outputs signals corresponding to the intake pipe internal pressure P _B on the downstream side of the throttle valve, the intake air temperature T ₁ at the compressor inlet, and the intake pipe internal pressure P _{1 on the upstream side of the compressor, which are output from the A-D converter 12} . is input, and a binary code signal corresponding to the intake air density correction coefficient γ _A stored in advance as a function of pressures P _B , P ₁ and temperature T ₁ is output.

The basic fuel injection amount Ti is corrected using this intake air density correction coefficient γ _A. That is, the signal corresponding to the basic fuel injection amount Ti outputted from the basic fuel injection amount storage circuit 15 or 16 is multiplied by the signal corresponding to the intake air density correction coefficient γ _A by the multiplication circuit 30 to calculate the actual injection amount T (= Ti×γ _A ) is calculated. This multiplier circuit 30 outputs a binary code signal corresponding to the calculated injection amount T.

The output of this multiplier circuit 30 is output from the waveform shaping circuits 3 and 4, and the reference position pulse signals Pa and Pb specifying the injection opening timing are outputted from the injection time counter 31,
Each of these counters 3 when added to 32
Preset to 1,32. Each of these counters 31 and 32 counts down from a preset value to 0 by a clock pulse CP inputted from the clock oscillation circuit 5, and outputs an injection signal during this down-counting period. The injection valve drive circuits 33 and 34 amplify the input injection signals with current to drive the injection valves 35 and 36 to inject fuel. In this way, fuel corresponding to the injection amount T is injected from the injection valves 35 and 36.

As explained above, according to the present invention, the rotational speed of a fuel injection engine having an intake pipe in which a compressor such as a turbocharger, an air cleaner, and an intake port of the engine are connected, and the intake air downstream of a throttle valve provided in the intake pipe. An electronic fuel injection control device for an internal combustion engine that determines a basic fuel injection amount based on parameters such as pipe pressure or throttle valve opening, and corrects the basic fuel injection amount by determining an intake air density correction coefficient according to the operating state of the engine. In the injection amount correction method, the intake air density correction coefficient is determined as a function of the intake pipe internal pressure and its intake air temperature on the upstream side of the compressor, and the intake pipe internal pressure downstream of the throttle valve. The pressure sensor for detecting the internal pressure in the intake pipe on the side can be omitted.

[Brief explanation of drawings]

Figure 1 is a characteristic diagram showing the relationship between the engine's intake negative pressure, the intake pipe internal pressure on the upstream side of the compressor (P _B /P ₁ ), and each intake air temperature (T _{B /T 1 ), and Figure 2 is a characteristic diagram showing the relationship between the engine's intake negative pressure, the intake pipe internal pressure on the upstream side of the compressor (P B} /P ₁ ), and each intake air temperature (T B /T 1 ). FIG. 3 is a schematic diagram of an engine with a turbocharger according to the present invention. 1, 2... Rotation sensor, 3, 4... Waveform shaping circuit, 5... Clock oscillation circuit, 6, 31, 32...
... Counter, 7, 10 ... Pressure sensor, 8 ... Throttle valve opening sensor, 9 ... Temperature sensor, 11
...Analog switch, 12...A-D converter,
13... Basic fuel injection amount calculation circuit, 26... Intake air density correction coefficient storage circuit, 33, 34... Injection valve drive circuit, 30... Multiplication circuit, 35, 36... Injection valve, AC... Air cleaner, C ...compressa,
T...Turbine, R...Resonance chamber, S
...Surge tank, In...Intake pipe, E...Engine, M...Muffler, TL...Throttle.

Claims (1)

[Claims] 1 Based on the rotational speed of a fuel injection engine that has an intake pipe in which the turbocharger compressor, air cleaner, and engine intake port are connected, and the parameters of the intake pipe internal pressure downstream of the throttle valve provided in the intake pipe or the throttle valve opening. In the injection amount correction method for an electronic fuel injection control device for an internal combustion engine, the injection amount correction method for an electronic fuel injection control device for an internal combustion engine determines a fuel injection amount and corrects the basic fuel injection amount by determining an intake air density correction coefficient according to the operating state of the engine. An injection amount of an electronic fuel injection control device for an internal combustion engine, characterized in that the intake air density correction coefficient is determined as a function of a parameter of an intake pipe internal pressure and its intake air temperature, and a parameter of an intake pipe internal pressure downstream of the throttle valve. Correction method.