JPH10280988A - Fuel injection controlling device and its method for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To calculate amount of injected fuel accurately even when atmospheric pressure changes. SOLUTION: Differential pressure between bottom pressure Pb of intake pressure and atmospheric pressure Pa, that is, relative pressure (Pa-Pb) is calculated, and a relative pressure correction factor KPa corresponding to the atmospheric pressure is calculated (steps 104, 105). Then, in order to correct the relative pressure (Pa-Pb) to the condition of standard atmospheric pressure, the relative pressure is multiplied by relative pressure correction factor KPa to calculate relative pressure correction value Pd1, and standard injection time TP is calculated based on this correction value Pd1 and engine speed NE (steps 106, 107). Next, fuel injection amount correction factor KPad depending on the atmospheric pressure Pa is calculated, and various correction factors K are calculated (steps 108, 109). Finally, invalid injection time TV is calculated based on supply voltage, and final injection time TAU is calculated using the standard injection time TP, the fuel injection amount correction factor KPad, various correction factors K, and the invalid injection time TV (steps 110, 111).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel injection control device and a fuel injection control method for an internal combustion engine which calculate a fuel injection amount based on a pressure difference between an intake pressure and an atmospheric pressure and a rotation speed of the internal combustion engine. is there.

[0002]

2. Description of the Related Art In general, in an internal combustion engine mounted on a vehicle, even if the intake pressure is the same, if the altitude of the road on which the vehicle runs is high and the atmospheric pressure is reduced, the amount of intake air changes. Is preferred. For this purpose, for example, in Japanese Patent Application Laid-Open No. 5-149187, the intake pressure of an internal combustion engine is detected by an intake pressure sensor, and the detected intake pressure is reduced to an intake pressure that gives an equivalent intake air amount under a reference atmospheric pressure (760 mmHg). Correction is performed using an atmospheric pressure correction coefficient for correction to obtain a corrected intake pressure, and a fuel injection amount is calculated based on the corrected intake pressure.

[0003] Incidentally, in order to reduce the deviation of the fuel injection amount (the deviation of the air-fuel ratio) due to the change in the atmospheric pressure, the difference between the intake pressure and the atmospheric pressure (hereinafter referred to as "relative pressure") is used. Although it is effective to calculate the fuel injection amount using the intake pressure (absolute pressure) in the technique disclosed in the above publication, the fuel injection amount is easily affected by changes in the atmospheric pressure. Even if the correction is performed using the correction coefficient, there is a disadvantage that the accuracy of calculating the fuel injection amount is reduced due to the correction error.

Therefore, as disclosed in Japanese Patent Application Laid-Open No. 60-247012, a relative pressure is detected, a fuel injection amount is calculated based on the relative pressure, and the fuel injection amount is corrected by an atmospheric pressure correction coefficient. There is something like that.

[0005]

The technique disclosed in the above publication aims at correcting the deviation of the fuel injection amount calculated from the relative pressure with an atmospheric pressure correction coefficient. Since the relationship with the atmospheric pressure (atmospheric pressure correction coefficient) is not uniquely determined, it is impossible to accurately correct the deviation of the fuel injection amount calculated from the relative pressure with the atmospheric pressure correction coefficient.
There is a drawback that a deviation in the air-fuel ratio occurs, which leads to an increase in exhaust emission and a decrease in drivability.

The present invention has been made in view of such circumstances, and therefore has as its object the ability to accurately calculate the fuel injection amount even if the atmospheric pressure changes, to reduce exhaust emissions and reduce driver emissions. It is an object of the present invention to provide a fuel injection control device and a fuel injection control method for an internal combustion engine, which can realize improvement in operability.

[0007]

In order to achieve the above object, according to the first and fourth aspects of the present invention, the differential pressure between the intake pressure and the atmospheric pressure (relative pressure) is adjusted by the relative pressure correcting means. After the basic injection amount is calculated by the basic injection amount calculating means based on the corrected relative pressure and the internal combustion engine speed, the basic injection amount is calculated by the final injection amount calculating means. The fuel injection amount is obtained by correcting with the injection amount correction coefficient corresponding to the atmospheric pressure.

In this way, in the process of calculating the basic injection amount from the relative pressure and the process of calculating the fuel injection amount from the basic injection amount, it is possible to make corrections in accordance with the atmospheric pressure. As a result, even if the atmospheric pressure changes, the fuel injection amount can be calculated with high accuracy, and reduction in exhaust emission and improvement in drivability can be realized.

In this case, a value obtained by dividing a reference atmospheric pressure by a detected atmospheric pressure may be used as the relative pressure correction coefficient. With this configuration, it is not necessary to store the map data of the relative pressure correction coefficient in the storage means, and the memory capacity of the storage means can be reduced (or the memory can be saved).

However, in the present invention, it goes without saying that the map data of the relative pressure correction coefficient may be stored in the storage means, and the relative pressure correction coefficient may be set from the map data in accordance with the detected atmospheric pressure.

In this case, it is preferable that the map data of the relative pressure correction coefficient and the map data of the injection amount correction coefficient are finely set in the vicinity of the standard atmospheric pressure which is a normal range. With this configuration, the relative pressure correction coefficient and the injection amount correction coefficient can be accurately obtained in accordance with the change in the atmospheric pressure in the service area, and the calculation accuracy of the fuel injection amount in the service area can be improved.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to a motorcycle will be described below with reference to the drawings. An intake manifold 12 is connected to an intake port 10 of each cylinder of an engine 11 that is an internal combustion engine, and an air box 13 is connected to an upstream side of the intake manifold 12 of each cylinder.
The air drawn into the air box 13 is drawn into the intake manifold 12 of each cylinder. An air cleaner 33 is mounted in the air box 13, and the air box 13 has an intake air temperature sensor 1 for detecting an intake air temperature.
4 is attached. Intake manifold 1 for each cylinder
In the middle of 2, a throttle valve 15 is attached,
The opening of the throttle valve 15 (throttle opening) is detected by a throttle opening sensor 16. Furthermore,
An intake pressure sensor 17 (intake pressure detection means) for detecting intake pressure is provided downstream of the throttle valve 15 in the intake manifold 12, and a fuel injection valve 18 is mounted near the intake port 10 of each cylinder. Have been.

On the other hand, the fuel pump 2
The fuel pumped at 0 is sent to the fuel pipe 21 → the fuel filter 22 → the fuel pipe 23 → the delivery pipe 24,
The fuel is distributed to the fuel injection valves 18 of each cylinder. Excess fuel in the delivery pipe 24 is returned to the fuel tank 19 through a path from the pressure regulator 25 to the return pipe 26.
The pressure regulator 25 adjusts the fuel pressure in the delivery pipe 24 so that the pressure difference between the fuel pressure in the delivery pipe 24 and the intake pressure becomes constant.

An ignition plug 27 is attached to the cylinder head of the engine 11 for each cylinder, and a high voltage generated on the secondary side of the ignition coil 28 is applied to the ignition plug 27 of each cylinder at each ignition timing to ignite. You. The engine 11 includes an engine speed sensor 29 (rotation speed detection means) for outputting a pulse signal (crank angle signal) at every predetermined crank angle for detecting the engine speed, and a cylinder discrimination sensor for discriminating a specific cylinder. 30 and a water temperature sensor 31 for detecting a cooling water temperature are attached. At a predetermined position of the vehicle body, an atmospheric pressure sensor 32 (atmospheric pressure detecting means) for detecting the atmospheric pressure is attached.

The output signals of the atmospheric pressure sensor 32 and the output signals of various sensors such as the aforementioned intake pressure sensor 17 are input to an engine control circuit 35. The engine control circuit 35 is mainly composed of a microcomputer, and a built-in ROM 45 (storage means) stores an ignition control routine, a fuel injection control routine of FIG. 2, a map data of FIGS. 3 and 4, and the like. Is stored.

The engine control circuit 35 executes a fuel injection control routine shown in FIG. 3 so that the differential pressure (relative pressure) between the bottom pressure Pb of the intake pressure and the atmospheric pressure Pa is changed to a relative pressure corresponding to the atmospheric pressure Pa. Pressure coefficient KPa, and the corrected relative pressure P
Basic injection time TP based on dl and engine speed NE
After calculating the basic injection amount, the basic injection time TP is corrected by an injection amount correction coefficient KPad corresponding to the atmospheric pressure Pa to obtain the final fuel injection time TAU (corresponding to the fuel injection amount).

Hereinafter, the processing content of the fuel injection control routine of FIG. 2 will be described. This routine is executed immediately before the fuel injection timing of each cylinder. When this routine is started, first, at step 101, the bottom pressure Pb of the intake pressure detected by the intake pressure sensor 17 is read. Here, as shown in FIG. 5, the bottom pressure Pb is the lowest point of the intake pressure that decreases during the intake stroke, and the intake pressure at the time of shifting from the intake stroke to the compression stroke is read as the bottom pressure Pb. This bottom pressure Pb is updated every cycle.

Thereafter, at step 102, the atmospheric pressure Pa detected by the atmospheric pressure sensor 32 is read, and at the next step 1
At 03, the engine speed NE detected from the output signal of the engine speed sensor 29 is read. Thereafter, the routine proceeds to step 104, where the differential pressure between the bottom pressure Pb of the intake pressure and the atmospheric pressure Pa, that is, the relative pressure (Pa-Pb) is calculated. At step 105, the relative pressure correction coefficient corresponding to the atmospheric pressure Pa is calculated. K
Calculate Pa. The calculation method of the relative pressure correction coefficient KPa is as follows.
One of the following methods (1) and (2) is used.

(1) A value obtained by dividing the reference atmospheric pressure (760 mmHg) by the detected atmospheric pressure Pa is defined as a relative pressure correction coefficient KPa (relative pressure correction coefficient KPa = reference atmospheric pressure / detected atmospheric pressure Pa).
). (2) The relationship between the atmospheric pressure Pa and the relative pressure correction coefficient KPa is determined in advance by a test or a simulation, and the relationship is set as map data (see FIG. 3).
And a relative pressure correction coefficient KPa corresponding to the detected atmospheric pressure Pa is obtained by searching map data.
The map data of the relative pressure correction coefficient KPa is finely set in the vicinity of the standard atmospheric pressure which is a normal area.

After calculating the relative pressure correction coefficient KPa by any one of the above methods (1) and (2),
Relative pressure (Pa-Pb) is compared with reference atmospheric pressure (760 mmHg)
Is calculated by multiplying the relative pressure (Pa−Pb) by the relative pressure correction coefficient KPa to calculate the relative pressure correction value Pdl [Pdl = (Pa−Pb) × KPa]. This step 10
The processing of No. 6 plays a role as a relative pressure correcting means referred to in the claims.

Thereafter, at step 107, the basic injection time T is calculated based on the relative pressure correction value Pdl and the engine speed NE.
Calculate P. In this calculation method, a relationship between the relative pressure correction value Pdl, the engine speed NE, and the basic injection time TP is obtained in advance by experiments or simulations, and a two-dimensional map of the basic injection time TP is created. It is stored in the ROM 45 of the circuit 35, and step 1
07, this map is searched, and the basic injection time TP according to the relative pressure correction value Pdl and the engine speed NE at that time is retrieved.
Is calculated. The processing of step 107 serves as a basic injection amount calculating means referred to in the claims.

After calculating the basic injection time TP, step 10
In step 8, an injection amount correction coefficient KPad corresponding to the atmospheric pressure Pa is calculated. In this calculation method, the relationship between the atmospheric pressure Pa and the injection amount correction coefficient KPad is obtained in advance by experiment or simulation, and the relationship is stored in the ROM 45 of the engine control circuit 35 as map data (see FIG. 4). An injection amount correction coefficient KPad corresponding to the atmospheric pressure Pa is obtained by searching map data. The map data of the injection amount correction coefficient KPad is finely set in the vicinity of the standard atmospheric pressure, which is a normal range.

Then, in the next step 109, various correction coefficients K other than the injection amount correction coefficient KPad are calculated. For example, the warm-up increase correction coefficient, the post-start increase correction coefficient, and the intake air temperature sensor 1 according to the output signal (cooling water temperature) of the water temperature sensor 31
Various correction coefficients K such as an intake air temperature correction coefficient corresponding to the output signal (intake air temperature) of No. 4 are calculated.

Thereafter, at step 110, the response delay time of the fuel injector 18 is calculated based on the power supply voltage, that is, the invalid injection time TV. At the next step 111, the pulse of the injection pulse outputted to the fuel injector 18 is calculated. The final injection time TAU, which is the width, is calculated by dividing the basic injection time TP and the injection amount correction coefficient KPad.
And the various correction coefficients K and the invalid injection time TV by using the following equation. TAU = TP × KPad × K + TV Here, the correction coefficient K includes various correction coefficients such as a warm-up increase correction coefficient, a post-start increase correction coefficient, and an intake air temperature correction coefficient. The processing of step 111 serves as a final injection amount calculating means referred to in the claims.

According to the above-described embodiment, the process of calculating the basic injection time TP from the relative pressure (Pa−Pb)
In the process of calculating the final injection time TAU from the basic injection time TP, the correction coefficient KP corresponding to the atmospheric pressure Pa
a, KPad, the basic injection time TP and the final injection time T
In order to correct both the AU and the AU, the final injection time T
AU can be calculated with high accuracy, and exhaust emission reduction and drivability can be improved.

Further, according to the present embodiment, since the map data of the relative pressure correction coefficient KPa and the map data of the injection amount correction coefficient KPad are finely set in the vicinity of the standard atmospheric pressure, which is a common use area, In the range, the relative pressure correction coefficient KPa and the injection amount correction coefficient KPad can be accurately obtained in accordance with the change in the atmospheric pressure Pa, and the calculation accuracy of the final injection time TAU in the normal range can be improved.

However, according to the present invention, the map data of the relative pressure correction coefficient KPa and the map data of the injection amount correction coefficient KPad do not necessarily need to be set in detail near the reference atmospheric pressure (common use area). The data setting interval may be the same as the setting interval of the other areas. Even in this case, the intended object of the present invention can be sufficiently achieved.

In this embodiment, the relative pressure correction coefficient KPa
Although the injection amount correction coefficient KPad is obtained from a one-dimensional map using the atmospheric pressure Pa as a parameter, it may be obtained from a two-dimensional map using the atmospheric pressure Pa and the engine speed NE as parameters.

In the present embodiment, the relative pressure is defined as the differential pressure between the bottom pressure Pb of the intake pressure and the atmospheric pressure Pa. However, the relative pressure is defined as the differential pressure between the average value of the intake pressure (average intake pressure) and the atmospheric pressure Pa. Is also good. Relative pressure = atmospheric pressure Pa-average intake pressure

In the present embodiment, the basic injection time TP is calculated based on the relative pressure correction value Pdl and the engine speed NE in the entire operation range. However, the relative pressure correction is performed only in the low load range. The basic injection time TP is calculated based on the value Pdl and the engine speed NE, and in the medium load / high load range, the basic injection time TP is calculated based on the throttle opening and the engine speed NE. good.

In this embodiment, the atmospheric pressure Pa is detected by the atmospheric pressure sensor 32. However, the output value of the intake pressure sensor 17 immediately after the start of the engine or the output value of the intake pressure sensor 17 after a predetermined time has elapsed since the engine was stopped. Is taken into the engine control circuit 35 as the atmospheric pressure Pa and the backup RA
M (not shown), and stores the stored value in the atmospheric pressure P
It may be used as a. In this case, the atmospheric pressure sensor 32 becomes unnecessary. In addition, the present invention is not limited to two-wheeled vehicles, but can be applied to four-wheeled vehicles.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an entire engine control system showing an embodiment of the present invention.

FIG. 2 is a flowchart showing the flow of processing of a fuel injection control routine;

FIG. 3 is a diagram conceptually showing a map of a relative pressure correction coefficient KPa.

FIG. 4 is a diagram conceptually showing a map of an injection amount correction coefficient KPad.

FIG. 5 is a time chart showing the behavior of intake pressure.

[Explanation of symbols]

11: engine (internal combustion engine), 12: intake manifold, 13: air box, 15: throttle valve, 1
6: throttle opening sensor; 17: intake pressure sensor (intake pressure detecting means); 18: fuel injection valve; 29: engine speed sensor (speed detecting means); 32: atmospheric pressure sensor (atmospheric pressure detecting means); 35 ... engine control circuit (basic injection amount calculation means, final injection amount calculation means), 45 ... ROM (storage means).

Continued on the front page (72) Inventor Akihisa Tamura 300 Takatsukacho, Hamamatsu-shi, Shizuoka Suzuki Co., Ltd.

Claims (4)

[Claims] 1. An engine control apparatus comprising: a rotational speed detecting means for detecting an internal combustion engine rotational speed; an atmospheric pressure detecting means for detecting an atmospheric pressure; and an intake pressure detecting means for detecting an intake pressure. A fuel injection control device for an internal combustion engine which calculates a fuel injection amount based on a pressure difference between an atmospheric pressure and an atmospheric pressure (hereinafter referred to as “relative pressure”) and an internal combustion engine rotation speed, wherein the relative pressure is reduced to the atmospheric pressure. Relative pressure correction means for correcting with a corresponding relative pressure correction coefficient, basic injection amount calculation means for calculating a basic injection amount based on the corrected relative pressure and the internal combustion engine speed, and setting the basic injection amount to atmospheric pressure. A fuel injection control device for an internal combustion engine, comprising: final injection amount calculation means for obtaining a fuel injection amount by correcting the fuel injection amount with a corresponding injection amount correction coefficient. 2. The fuel injection control device for an internal combustion engine according to claim 1, wherein the relative pressure correction means uses a value obtained by dividing a reference atmospheric pressure by a detected atmospheric pressure as the relative pressure correction coefficient. 3. A storage means for storing map data of the relative pressure correction coefficient and map data of the injection amount correction coefficient, wherein the map data of the relative pressure correction coefficient and the map data of the injection amount correction coefficient are reference data. 2. The fuel injection control device for an internal combustion engine according to claim 1, wherein the data is finely set near the atmospheric pressure. 4. A fuel injection control method for an internal combustion engine that calculates a fuel injection amount based on a pressure difference between an intake pressure and an atmospheric pressure (hereinafter referred to as “relative pressure”) and an internal combustion engine speed. Correct with the relative pressure correction coefficient according to the atmospheric pressure,
After calculating a basic injection amount based on the corrected relative pressure and the internal combustion engine speed, the basic injection amount is corrected by an injection amount correction coefficient corresponding to the atmospheric pressure to obtain a fuel injection amount. A fuel injection control method for an internal combustion engine.