JPH0226692B2 - - 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 system for an internal combustion engine, there is a method of determining the basic amount of fuel injection using either the intake pipe internal pressure downstream of the engine's throttle valve or the throttle valve opening, and the engine rotational speed. The method for determining the basic injection amount is to use the engine speed Ne and the intake pipe internal pressure downstream of the throttle valve in a relatively low engine load region.
A matrix memory (P _B −Ne map) with PB as a parameter is used, and in a relatively high load region, a matrix memory (θth−Ne map) with engine speed Ne and throttle valve opening θth as parameters is used.
There is a hybrid method that determines the basic fuel injection amount Ti using the Ne map.

Furthermore, in turbocharged engines,
Pressure P ₂ and temperature of the intake air downstream of the compressor
T ₂ is detected, the intake air density correction coefficient γ _A is determined using the detected P ₂ and T ₂ as parameters, and the basic fuel injection amount Ti is corrected by the correction coefficient γ _A , and the intake air temperature and It is required to correct the fuel injection amount according to changes in pressure, that is, density.

Therefore, pressure sensors are required to detect the intake pipe internal pressures P ₁ and P ₂ on the upstream and downstream sides of the compressor for determining the basic fuel injection amount P _B and for correcting the intake air density. A diaphragm type semiconductor pressure sensor is used as such a pressure sensor, but such a pressure sensor is expensive, and as a result, the system becomes expensive, so there is a demand for a system that is as inexpensive as possible.

The present invention has been made in view of the above points, and an object of the present invention is to provide a system with a reduced number of sensors. In order to achieve this object, the present invention provides 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;
An internal combustion engine that determines a basic fuel injection amount based on an intake pipe internal pressure parameter downstream of a throttle valve provided in the intake pipe, 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 for an electronic fuel injection control device, the intake air temperature downstream of the throttle valve and the intake pipe internal pressure downstream of the throttle valve for determining the basic fuel injection amount are used as parameters, and the intake air density correction coefficient is set as a function thereof. The present invention provides a method for correcting the injection amount of an electronic fuel injection control device for an internal combustion engine.

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

The intake air density correction coefficient γ _A for correcting the basic fuel is expressed by the following equation.

γ _A = P ₂ / P ₀ × T ₀ / T ₂ ...... (1a) As shown in Figure 2, air passing upstream of the throttle TL always passes downstream of the throttle TL, which is communicated with the intake pipe In. Therefore, it can be replaced by the following formula.

γ _A = (P _B / P ₀ ) ⁿ - ^1/n × T ₀ / T _B (n is a polytropic index) ... (1b) Here, the value P ₀ is standard atmospheric pressure (760 mmHg), and T ₀ is standard temperature (25°C), P _B represents the intake pipe internal pressure downstream of the engine throttle valve, and T _B represents the intake air temperature downstream of the engine throttle valve.

In this equation (1b), the values P ₀ and T ₀ are constants. Therefore, P _B for determining the basic fuel injection amount is used for determining γ _A , and a new intake air temperature T _B sensor is provided _.
It becomes possible to obtain the intake air density correction coefficient γ _A from the value.

FIG. 1 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 reference position of the engine camshaft CA, and in this embodiment, they are arranged so as to output pulses that are 180 degrees out of phase with each other.
Each of these sensors 1 and 2 is connected to a waveform shaping circuit 3,
4, and the output side of the latter is connected to the engine revolution counter 6 and the injection time counter 31, 3.
Connected to the input side of 2. The clock oscillation circuit consists of counters 31, 32 and analog switch 11.
is connected to the input side of the counters 6, 31,
A clock pulse CP is supplied to the switch 32, and a control pulse φ is supplied to the analog switch 11.

FIG. 2 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 T _B through E _X , and after driving this turbine T, the muffler M
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.

As shown in FIG. 2, the pressure sensor 7 detects the pressure P _B on the downstream side of the throttle valve TL in the intake pipe In 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 a throttle valve disposed in the intake pipe of the engine, and is composed of, for example, a potentiometer. The temperature sensor 9 detects the engine intake air temperature, that is, the temperature T _B downstream of the throttle valve. The output sides of each pressure sensor 7, throttle valve opening sensor 8, and temperature sensor 9 are connected to each input side of an analog switch 11, respectively, and the output side of the analog switch 11 is connected to an analog-to-digital converter (hereinafter referred to as A- (referred to as D converter)
It is connected to the input side of 12.

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 each input side of the intake air density correction coefficient storage circuit 26.
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 above configuration 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 from each other 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.

The intake negative pressure of the engine is detected by the pressure sensor 7, and the throttle valve opening θth is detected by the throttle valve opening sensor 8.
Accordingly, the intake air temperature T _B downstream of the throttle is detected by the temperature sensor 9, respectively. Each of these detected analog signals is sequentially converted to A through an analog switch 11 which is switched by a control pulse φ applied from a clock oscillation circuit 5 at a predetermined timing.
-D converter 12 and converted into corresponding binary code signals.

The comparison circuit 14 compares the A-D converted signal corresponding to the throttle valve opening θth with the set value θth1,
If θth<θth1, basic fuel injection amount memory circuit 1
5, and when θth>θth1, 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
Ne and a signal corresponding to the intake pipe internal pressure P _B downstream of the throttle valve output from the A-D converter 12 are input, and the intake pipe internal pressure P _B downstream of the throttle valve and the engine rotation speed Ne are input. A binary code signal corresponding to the basic fuel injection amount Ti stored as a function of is output. The basic fuel injection amount storage circuit 16 receives a signal corresponding to the engine rotation speed Ne output from the counter 6 and the A-D converter 12.
A signal corresponding to the throttle valve opening θth outputted from is input, and a binary code signal corresponding to the basic fuel injection amount Ti, which is stored in advance as a function of the throttle valve opening θth and the engine speed Ne, is output. do. That is, when θth<θth1, the basic fuel injection amount storage circuit 15 outputs a binary code signal, and when θth>θth1, 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 inputs each signal corresponding to the current intake pipe internal pressure P _B downstream of the throttle valve and the current intake air temperature T _B output from the A-D converter 12, and preliminarily calculates the current intake pipe internal pressure downstream of the throttle valve. pressure
P _B , and a binary code signal corresponding to the intake air density correction coefficient γ _A stored as a function of the intake air temperature T _B downstream of the throttle valve.

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 multiplication circuit 30 is the waveform shaping circuit 3, 4
The reference position pulse signals Pa and Pb output from the injection time counter 3 and specifying the injection start timing are output from the injection time counter 3.
1 and 32, these counters 31 and 32 are preset. 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-injected 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 pipe downstream of a throttle valve provided in the intake pipe. In an injection amount correction method for an electronic fuel injection control device for an internal combustion engine, the basic fuel injection amount is determined based on a pressure parameter, and the basic fuel injection amount is corrected by determining an intake air density correction coefficient according to the operating state of the engine. , the intake air temperature downstream of the throttle valve and the intake pipe internal pressure downstream of the throttle valve for determining the basic fuel injection amount are used as parameters, and the intake air density correction coefficient is determined as a function of the intake air temperature, thereby reducing the number of expensive pressure sensors. The system can be simplified.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of an injection amount correction method for an electronic fuel injection control device for an internal combustion engine according to the present invention, and FIG. 2 is a schematic diagram of a turbocharged engine according to the present invention. 1, 2... Rotation sensor, 3, 4... Waveform shaping circuit, 5... Clock oscillation circuit, 6, 31, 32...
... Counter, 7 ... 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 density correction coefficient storage circuit, 30 ... Multiplication circuit, 33, 34
... Injection valve drive circuit, 35, 36 ... Injection valve,
AC...Air cleaner, C...Compressor, T
...Turbine, In...Intake pipe, E...Engine,
M...muffler, TL.....throttle valve, E _X ...exhaust pipe.

Claims (1)

[Claims] 1. The basic fuel injection amount is determined 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 intake pipe internal pressure downstream of the throttle valve provided in the intake pipe. In the injection amount correction method of an electronic fuel injection control device for an internal combustion engine, which corrects the basic fuel injection amount by determining an intake air density correction coefficient according to the operating state of the engine, the intake air temperature downstream of the throttle valve and the basic fuel injection amount are determined. An injection amount correction method for an electronic fuel injection control device for an internal combustion engine, characterized in that the intake pipe internal pressure downstream of a throttle valve for determining the fuel injection amount is used as a parameter, and the intake air density correction coefficient is determined as a function thereof. .