JPH05125984A - Fuel injection amount controller for internal combustion engine - Google Patents

Abstract

PURPOSE:To properly control the amount of fuel supplied to an internal combustion engine, especially one that uses mixed fuel of gasoline and alcohol, in starting the engine at high temperatures. CONSTITUTION:A fuel injection amount controller includes an NE sensor 5 for detecting the operating state of an internal combustion engine 1, a fuel injection amount calculation means 3c for calculating the amount of fuel injected by a fuel injection valve 12 according to operating states, an ALC sensor 23 for detecting the alcohol concentration of fuel, a TW sensor 2 for detecting the temperature of cooling water, and a pressure governing valve 17 for controlling injection pressure of fuel to a constant level when cooling water temperature is higher than a predetermined value. The controller further includes a solenoid valve 21 for further raising injection pressure, a PBA sensor 10 for detecting pressure within a suction pipe 6, a PA sensor 26 for detecting atmospheric pressure, a differential pressure calculation means 3b for calculating the differential pressure between the internal pressure of the suction pipe 6 and atmospheric pressure, and a fuel injection amount correction means 3b by which the amount of injection of fuel calculated by the fuel injection amount calculation means 3b is corrected through subtraction according to the pressure detected by the PBA sensor 10 when the injection pressure is increased.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel injection amount control device at the time of starting an internal combustion engine, particularly an internal combustion engine that uses a mixture of gasoline and alcohol.

[0002]

2. Description of the Related Art Conventionally, as a technique of this type, a fuel pressure supplied from a fuel injection valve is kept constant by a pressure regulator (pressure regulator), and percolation in the fuel injection valve is performed at a high temperature. To prevent this, a technique for controlling the fuel pressure higher than usual is disclosed in JP-A-2-95.
No. 747 is disclosed.

[0003]

However, in the prior art, when the fuel pressure is controlled to be higher than usual, the differential pressure between the pressure in the fuel injection valve and the intake pipe pressure is equal to the negative pressure in the intake pipe. Since the fuel injection amount increases, the fuel injection amount becomes larger than the fuel amount required by the operating state, and the exhaust emission may deteriorate. Further, when a mixed fuel obtained by mixing gasoline and alcohol is used, if the alcohol concentration in the mixed fuel is within a predetermined range, the vapor pressure rises, percolation easily occurs, and the fuel injection amount cannot be accurately controlled.

Therefore, the present invention has been made in view of the conventional problems, and an object thereof is to provide an internal combustion engine, particularly an internal combustion engine at the time of high temperature start of an internal combustion engine using a mixed fuel of gasoline and alcohol. It is an object of the present invention to provide a fuel injection amount control device for an internal combustion engine, which is capable of appropriately controlling the fuel supply amount.

[0005]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention provides an operating state detecting means for detecting an operating state of an internal combustion engine, and an internal combustion engine according to the operating state detected by the operating state detecting means. A fuel injection amount calculation means for calculating a fuel injection amount injected by a fuel injection valve attached to an intake pipe, a pressure control means for constantly controlling an injection pressure of fuel injected from the fuel injection valve, and an internal combustion engine Of the internal combustion engine having cooling water temperature detecting means for detecting the temperature of the cooling water, and injection pressure increasing means for increasing the injection pressure when the cooling water temperature detected by the cooling water temperature detecting means is higher than a predetermined value. In the quantity control device, the intake pipe internal pressure detecting means for detecting the pressure in the intake pipe downstream of the throttle valve of the internal combustion engine, and the intake pipe internal pressure detecting means for detecting the increase in the injection pressure are detected. Those having a fuel injection quantity correcting means for subtracting correcting the fuel injection amount calculated by the fuel injection quantity calculating means in accordance with the trachea pressure.

Further, an atmospheric pressure detecting means for detecting the atmospheric pressure, and a differential pressure for calculating a differential pressure between the intake pipe internal pressure detected by the intake pipe internal pressure detecting means and the atmospheric pressure detected by the atmospheric pressure detecting means. It is preferable that the fuel injection amount correction unit includes a calculation unit so that the fuel injection amount injected from the fuel injection valve decreases as the differential pressure calculated by the differential pressure calculation unit increases. In addition, an alcohol concentration detecting means for detecting the alcohol concentration in the mixed fuel in which gasoline and alcohol are mixed is provided, and the injection pressure increasing means increases the vapor pressure of the mixed fuel based on the alcohol concentration detected by the alcohol concentration detecting means. When within the specified range,
It is also possible to increase the injection pressure.

[0007]

The control is performed such that the valve opening time of the fuel injection valve becomes shorter as the differential pressure calculated by the differential pressure calculating means at the time of high temperature start increases. Further, when the temperature is high and the alcohol concentration is within a predetermined range and the differential pressure calculated by the differential pressure calculating means is large, the valve opening time of the fuel injection valve is controlled to be short.

[0008]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is an overall configuration diagram of a fuel injection amount control device for an internal combustion engine according to the present invention, FIG. 2 is a flowchart showing an operation procedure of the fuel injection amount control device for an internal combustion engine according to the present invention, and FIG. 3 is a correction coefficient KREG calculated. It is a diagram showing an example of a correction coefficient table for doing.

The internal combustion engine (engine) 1 includes an engine 1
An engine cooling water temperature (TW) sensor 2, which is a cooling water temperature detecting means such as a thermistor, is attached to the peripheral wall of the cylinder filled with the cooling water of the cylinder block, and electricity corresponding to the engine cooling water temperature TW detected by the TW sensor 2 is inserted. The signal is input to the electronic control unit (ECU) 3.

An engine speed (NE) sensor 5, which is an operating condition detecting means, is mounted around the cam shaft or crank shaft (not shown) of the engine 1. The NE sensor 5 outputs a pulse signal (TDC pulse signal) at a predetermined crank angle position for every 180 ° rotation of the crankshaft of the engine 1, and is input to the ECU 3.

A throttle body 7 is arranged in the middle of an intake pipe 6 of the engine 1, and a throttle valve 7a is provided inside the throttle body 7.
Is provided. A throttle valve opening (θTH) sensor 8 is connected to the throttle valve 7a, and an electric signal corresponding to the opening θTH of the throttle valve 7a is input to the ECU 3.

An intake pipe internal pressure (PBA) sensor 10, which is an intake pipe internal pressure detecting means, is mounted via a branch pipe 9 downstream of the throttle valve 7a of the intake pipe 6, and the intake air detected by the PBA sensor 10 is installed. An electric signal corresponding to the pressure PB in the pipe 6 is input to the ECU 3.

An intake air temperature (TA) sensor 11 is attached to the wall of the intake pipe 6 downstream of the branch pipe 9, and an electric signal corresponding to the intake air temperature TA detected by the TA sensor 11 is sent to the ECU 3. Is entered.

The fuel injection valve 12 is provided for each cylinder between the engine 1 and the throttle valve 7a on the upstream side of an intake valve (not shown) of the intake pipe 6. Fuel injection valve 12
Is connected to the fuel pump 14 via the first fuel supply pipe 13, and its valve opening time is controlled by a drive signal from the ECU 3. Further, the fuel pump 14 is connected to the fuel tank 16 via the second fuel supply pipe 15.

Reference numeral 17 is a pressure regulating valve which is a pressure control means, and the inside of the casing of the pressure regulating valve 17 is divided into a negative pressure chamber and a fuel chamber by a diaphragm (not shown), and the negative pressure chamber is connected via a negative pressure passage 18. The fuel chamber is connected to the downstream side of the throttle valve 7a in the intake pipe 6, and the fuel chamber is connected to the fuel supply pipe 13 via a conduit 19 and the fuel tank 1 via a return conduit 20.
6 are connected respectively.

An injection pressure increasing means for increasing the injection pressure of the fuel injected from the fuel injection valve 12 when the engine cooling water temperature TW detected by the TW sensor 2 is higher than a predetermined value in the middle of the negative pressure passage 18. Solenoid valve (pressure
A regulator control solenoid valve) 21 is provided. The solenoid valve 21 is a normally closed solenoid valve,
It is composed of a solenoid (not shown) and a valve element driven by the solenoid. The solenoid is electrically connected to the ECU 3 and also connected to an ignition switch (not shown).

The solenoid valve 21 communicates the negative pressure chamber of the pressure regulating valve 17 with the atmosphere through the air cleaner 22 when the solenoid is energized, and introduces the negative pressure on the downstream side of the throttle valve 7a into the negative pressure chamber in the deenergized state. To do. Normally, the solenoid is deenergized, and the pressure regulating valve 17 opens and closes the valve body in accordance with the fuel pressure to regulate the amount of fuel flowing back to the fuel tank 16, whereby the fuel pressure in the fuel supply pipe 13 is adjusted. The difference between the absolute pressure in the intake pipe 6 and the absolute pressure in the intake pipe 6 is maintained at a constant value. Further, when the solenoid of the solenoid valve 21 is energized, the negative pressure chamber of the pressure regulating valve 17 is opened to the atmosphere via the air cleaner 22, and the fuel pressure in the fuel supply pipe 13 is controlled to be constant.

Further, an alcohol concentration (ALC) sensor 23, which is an alcohol concentration detecting means, is attached to the pipe wall of the first fuel supply pipe 13 on the downstream side of the fuel pump 14.
An electric signal corresponding to the alcohol concentration ALC detected by the C sensor 23 is input to the ECU 3.

Furthermore, an exhaust pipe 24 of the engine 1 is an oxygen concentration detecting means serving O ₂ sensor 25 is mounted for detecting the oxygen concentration in the exhaust gas, the oxygen in the exhaust gas detected by the O ₂ sensor 25 The electric signal according to the concentration is ECU3
Entered in. Further, 26 is an atmospheric pressure (PA) sensor which is an atmospheric pressure detecting means for detecting the atmospheric pressure.

The ECU 3 shapes the waveforms of the input signals from the above various sensors, corrects the voltage level to a predetermined level, converts the analog signal into a digital signal, and the like, and the central processing unit. Device (CPU) 3
b, a storage means 3c including a ROM for storing various calculation programs executed by the CPU 3b and a predetermined table and a RAM for storing calculation results, and an output for outputting a drive signal to the fuel injection valve 12 and the solenoid valve 21. It is composed of a circuit 3d.

The CPU 3b discriminates various engine operating states based on various sensor output signals which are engine parameters, and opens the fuel injection valve 12 according to the discriminated engine operating states and in synchronization with the TDC pulse signal. The fuel injection time Tout to be valved is calculated.

First, while the engine 1 is being started, the fuel injection time Tout is calculated based on the following equation 1 in the start mode.

[0023]

## EQU1 ## Tout = TiCR × KNE × KALCCR × K ₁ + K ₂ where TiCR is the fuel injection valve 12 in the starting mode.
Is a reference value for the injection time of and is determined according to the engine cooling water temperature TW by the TiCR map. Also, KNE
Is determined according to the engine speed NE by the KNE table.

KALCCR is an alcohol concentration correction coefficient in the starting mode, which is determined according to the alcohol concentration detected by the ALC sensor 23 by the KALCCR table, and its average value is the actual alcohol concentration correction coefficient KALC value, which will be described later. Is applied to Equation 1 above. K ₁ and K ₂ are other correction coefficients and correction variables, which are determined according to the battery voltage and the like.

Next, after the start of the engine 1 is completed, the basic mode is entered, and the fuel injection time Tout is calculated by the following equation (2).
To calculate.

[0026]

[Equation 2] Tout = Ti × KALC × K ₃ + K ₄ Here, Ti is a reference value at the injection time of the fuel injection valve 12 in the basic mode, and the engine speed NE and the absolute pressure in the intake pipe 6 are calculated from the Ti map. It is determined according to PB.

KALC is an alcohol concentration correction coefficient in the basic mode. In the basic mode, the alcohol concentration detected by the ALC sensor 23 by the KALC table when the engine 1 is in a steady state and by the KALCT table when the engine 1 is in an acceleration state. According to K
Determined as ALC, KALCT. In the basic mode as well, the average value is applied as the KALC value in the above-mentioned formula 2.

K ₃ and K ₄ are the opening θT of the throttle valve 7a.
The correction coefficient and the correction variable are set by H and other parameter values indicating the engine operating state, and are set so that the starting characteristic, the acceleration characteristic, and the like are optimum.

As described above, the alcohol concentration correction coefficient KALC, which is a main coefficient for determining the fuel injection time Tout, is
Since it will greatly affect the air-fuel ratio control, it must be calculated accurately at the time of starting and after starting.

Here, at the time of high temperature start and at a predetermined time (for example, about 30 seconds) after the start, the equations 1 and 2 are given.
At the fuel injection time Tout calculated based on
The negative pressure chamber of the pressure regulating valve 17 is opened to the atmosphere via the air cleaner 22 while the solenoid No. 1 is energized (ON state), so that the pressure difference between the pressure inside the fuel injection valve 12 and the pressure inside the intake pipe 6 is reduced. Is increased by the negative pressure in the intake pipe 6 (the pressure difference between the inside and outside of the fuel injection valve 12 is increased), so that the fuel supply amount to the intake pipe 6 is increased and the exhaust gas characteristic is deteriorated. Particularly, the alcohol concentration is within a predetermined range (for example, about 10% to 4%).
(0%), the vapor pressure rises and percolation easily occurs in the fuel injection valve 12, so it is necessary to turn on the electromagnetic valve 21 to raise the fuel pressure in the fuel supply pipe 13.

Therefore, a predetermined correction coefficient KREG (KREG) is added to the fuel injection time Tout calculated based on the equations 1 and 2.
REG <1.0) and subtraction-corrected fuel injection time T
The out is used to control the fuel injection amount at the high temperature start and for a predetermined time after the start.

In this way, the CPU 3b controls the intake pipe 6 of the internal combustion engine 1 according to the operating state detected by the NE sensor 5.
Fuel injection amount calculation means for calculating the fuel injection amount injected by the fuel injection valve 12 attached to the storage means 3
The ALC sensor 23 based on the correction coefficient table (KALCCR table, KALC table) stored in c.
The correction coefficient calculation means for calculating the alcohol concentration correction coefficients KALCCR, KALC (hereinafter, simply referred to as KALC) according to the alcohol concentration ALC detected by, and the average value of the correction coefficients from the correction coefficients calculated by the correction coefficient calculation means. Means for calculating average value and atmospheric pressure (PA)
A differential pressure calculating means for calculating a differential pressure (relative pressure PBREL) between the atmospheric pressure PA detected by the sensor 26 and the pressure PB in the intake pipe 6 detected by the PBA sensor 10, and this differential pressure calculating means. And a fuel injection amount correction means for correcting the fuel injection amount injected from the fuel injection valve 12 according to the relative pressure PBREL.

The fuel injection amount correction means is arranged to change the fuel injection time Tou.
The correction coefficient KREG for adjusting t is calculated from the correction coefficient table shown in FIG. 3 based on the value of the relative pressure PBREL, and the correction coefficient KREG is added to the fuel injection time Tout calculated based on Expression 1 and Expression 2. It is composed of multiplication means for multiplying by.

The operation procedure of the fuel injection amount control apparatus for an internal combustion engine according to the present invention having the above-described structure is performed according to the flow chart (fuel injection amount correction subroutine) shown in FIG.

First, is the alcohol concentration ALC detection value from the ALC sensor 23 read via the input circuit 3a and the alcohol low concentration value ALCL (for example, alcohol concentration 10%) stored in the storage means 3c (ROM) or more? If it is judged to be above (S1), and if it is judged to be above, it is further judged whether or not the alcohol concentration ALC detection value is equal to or lower than the alcohol high concentration value ALCH (for example, alcohol concentration 40%) stored in the storage means 3c (ROM). It is determined (S2).

Then, the alcohol concentration ALC detection value is
If it is determined that the alcohol high concentration value ALCH or less, it is determined whether the engine cooling water temperature TW is high (for example, 95 ° C. or higher) (S3). If it is determined that the temperature is high, the solenoid of the solenoid valve 21 is attached in step S4. Turn on (turn on).

Next, the differential pressure (relative pressure PBREL) between the atmospheric pressure PA detected by the atmospheric pressure (PA) sensor 26 and the pressure PB in the intake pipe 6 detected by the PBA sensor 10.
Is calculated (S5). In this way, the relative pressure PBREL is obtained because when the solenoid of the solenoid valve 21 is in the energized state (on state), the negative pressure chamber of the pressure regulating valve 17 is opened to the atmosphere via the air cleaner 22, and the inside of the fuel injection valve 12 is opened. Pressure and intake pipe 6
Since the differential pressure from the internal pressure PB rises by the negative pressure in the intake pipe 6, the fuel injection amount becomes larger than the fuel amount required by the operating state, and the exhaust emission may deteriorate. Therefore, the relative pressure PBREL is calculated to correct the fuel injection amount.

Then, the correction coefficient KREG value corresponding to the value of the relative pressure PBREL is calculated based on the correction coefficient table shown in FIG. 3 stored in advance in the storage means 3c (ROM) (S6).

The correction coefficient table shown in FIG. 3 is a correction coefficient table at the time of high temperature starting, in which the horizontal axis shows the relative pressure PBREL value and the vertical axis shows the correction coefficient KREG value. The correction coefficient table includes a plurality of predetermined relative pressures P.
BREL1, PBREL2, ... For PBREL8, predetermined correction coefficient values KREG1, KREG2, ... KREG, respectively
8 are provided. Then, when there is a predetermined relative pressure value, the correction coefficient value is calculated by linear interpolation.

Further, the correction coefficient value K obtained in step S6
The fuel injection amount correction subroutine program is ended by multiplying REG by the fuel injection time Tout calculated based on Formula 1 and Formula 2 to obtain the fuel injection time Tout at the high temperature start and at a predetermined time after the start (S7).

[0041]

As described above, according to the present invention, the internal combustion is prevented by preventing percolation in the fuel injection valve at the time of high temperature starting and adjusting the opening time of the fuel injection valve to be shorter than usual. The amount of fuel supplied to the engine can be appropriately controlled to prevent deterioration of exhaust emission. Further, the air-fuel ratio control can appropriately control the fuel supply amount to the internal combustion engine without relying only on the feedback of the oxygen concentration in the exhaust gas.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of a fuel injection amount control device for an internal combustion engine according to the present invention.

FIG. 2 is a flowchart showing an operation procedure of a fuel injection amount control device for an internal combustion engine according to the present invention.

FIG. 3 is a diagram showing an example of a correction coefficient table for calculating a correction coefficient KREG.

[Explanation of symbols]

1 ... Engine (internal combustion engine), 2 ... Engine cooling water temperature (T
W) sensor (cooling water temperature detecting means), 3b ... CPU (fuel injection amount calculating means, differential pressure calculating means, fuel injection amount correcting means), 5 ... engine speed (NE) sensor (operating state detecting means), 10 ... PBA sensor (intake pipe internal pressure detecting means), 12 ... Fuel injection valve, 17 ... Pressure regulating valve (pressure control means), 21 ... Electromagnetic valve (injection pressure increasing means), 23 ... Alcohol concentration (ALC) sensor (alcohol concentration detecting means) ), 26 ... Atmospheric pressure (PA) sensor (atmospheric pressure detection means).

Claims (3)

[Claims] 1. An operating state detecting means for detecting an operating state of an internal combustion engine, and fuel injected by a fuel injection valve attached to an intake pipe of the internal combustion engine according to the operating state detected by the operating state detecting means. Fuel injection amount calculation means for calculating the injection amount, pressure control means for controlling the injection pressure of the fuel injected from the fuel injection valve to a constant value, cooling water temperature detection means for detecting the temperature of the cooling water of the internal combustion engine, When the cooling water temperature detected by the cooling water temperature detecting means is higher than a predetermined value, in a fuel injection amount control device for an internal combustion engine having an injection pressure increasing means for increasing the injection pressure, an intake pipe downstream of a throttle valve of the internal combustion engine Intake pipe internal pressure detection means for detecting the pressure of the intake pipe, and the fuel injection amount calculation means according to the intake pipe internal pressure detected by the intake pipe internal pressure detection means when the injection pressure increases. A fuel injection amount control device for an internal combustion engine, comprising: a fuel injection amount correction means for subtractively correcting the calculated fuel injection amount. 2. The fuel injection amount control device according to claim 1, wherein the atmospheric pressure detecting means for detecting atmospheric pressure, the intake pipe internal pressure detected by the intake pipe internal pressure detecting means and the atmospheric pressure detecting means are detected. A pressure difference calculating means for calculating a pressure difference from the atmospheric pressure, wherein the fuel injection amount correcting means decreases the fuel injection amount injected from the fuel injection valve as the pressure difference calculated by the pressure difference calculating means increases. A fuel injection amount control device for an internal combustion engine, characterized in that 3. The fuel injection amount control device according to claim 1 or 2, further comprising an alcohol concentration detecting means for detecting an alcohol concentration in a mixed fuel in which gasoline and alcohol are mixed, wherein the injection pressure increasing means is the alcohol. A fuel injection amount control device for an internal combustion engine, wherein the injection pressure is increased when the alcohol concentration detected by the concentration detecting means is within a predetermined range in which the vapor pressure of the mixed fuel increases.