JPH0599028A - Fuel injection control device of internal combustion engine - Google Patents

Abstract

PURPOSE:To adjust a fuel injection amount according to an intake air temperature by setting an intake air temperature correction coefficient not so much influenced by the intake air temperature, when an engine is in a high load condition, and the intake air temperature exceeds a prescribed intake air temperature. CONSTITUTION:An intake air temperature correction coefficient which is set according to an intake air temperature, is set according to whether an engine is in a low load condition or in a high load condition. Namely, when the engine is in a low load condition, an intake air temperature correction coefficient setting means 11A for low load condition is selected, and when the engine is in a high load condition, an intake air temperature correction coefficient setting means 12A for high load condition is selected. In each setting means 11A, 12A, the intake air temperature correction coefficient Kta is outputted to a fuel injection amount calculating means 100 according to the intake air temperature Ta. After the intake air temperature Ta exceeds a prescribed intake air temperature, influence of the intake air temperature Ta on the intake air temperature correction coefficient Kta which is set in high load condition, is smaller than that on the intake air temperature correction coefficient Kta which is set in low load condition. It is thus possible to match a fuel injection amount at the time of operation in high load condition with demand of the engine.

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 for an internal combustion engine, and more particularly to a fuel injection control device for an internal combustion engine which adjusts a fuel injection amount according to intake air temperature.

[0002]

2. Description of the Related Art Various fuel injection control devices for internal combustion engines have been proposed in the past.
Japanese Patent Publication No. 176427 discloses a fuel injection control device that adjusts the fuel injection amount according to the intake air temperature. This is performed to compensate for the density of intake air that differs depending on the temperature, and the fuel injection amount correction amount according to the intake air temperature is determined based on the output signal of the intake air temperature sensor arranged in the air cleaner, for example. To be done.

[0003]

During idle operation or extremely low load, the intake air flow rate is relatively small, so the temperature of the temperature detecting portion of the intake air temperature sensor matches the actual intake air temperature.

On the other hand, when the engine becomes high temperature during high load operation, the temperature detecting portion of the intake air temperature sensor indicates the high temperature by widening the ambient temperature, but the actual intake air temperature (actual intake air temperature) is the intake air flow rate. There are many cases, so the temperature may not be so high. That is, when the intake air temperature (detected intake air temperature) detected by the intake air temperature sensor is high during high load operation, the detected intake air temperature may be higher than the actual intake air temperature.

As a result, if the fuel injection amount correction amount is determined only based on the detected intake air temperature, the fuel injection amount corresponding to the intake air temperature from the intake air temperature sensor is required by the engine, especially during high load operation. It may be different from the injection amount.

The present invention has been made to solve the above-mentioned problems, and an object thereof is to control the fuel injection of an internal combustion engine so that the fuel injection amount at the time of high load operation can meet the demand of the engine. To provide a device.

[0007]

In order to solve the above-mentioned problems, an intake air temperature correction coefficient set in accordance with the intake air temperature,
Furthermore, the internal combustion engine is set according to whether it is in a low load state or a high load state, and after the intake air temperature exceeds a predetermined intake temperature, the intake temperature correction coefficient set in the high load state is set. The feature is that the influence of the intake air temperature is made smaller than the intake air temperature correction coefficient set in the low load state.

After the intake air temperature exceeds the predetermined intake air temperature,
Another feature is that the intake air temperature correction coefficient set in the high load state is a fixed value.

[0009]

With the above configuration, when the internal combustion engine is in a high load state and the intake air temperature exceeds the predetermined intake air temperature, the intake air temperature correction coefficient that is less affected by the intake air temperature is set. ..

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to the drawings. In this embodiment, the present invention is applied to a motorcycle.

FIG. 2 is a block diagram of an embodiment of the present invention. In the figure, an air cleaner 56 is provided in the vicinity of the engine, and an intake air temperature sensor 1 for detecting an intake air temperature Ta and an intake pressure sensor 7 for detecting an intake pressure Pb are arranged inside the air cleaner 56. The air intake of the air cleaner 56 is provided on the side of the air cleaner 56.

A throttle valve is provided in the intake passage extending from the air cleaner 56 to the engine, and an injector 29 is provided in the vicinity of the throttle valve. A throttle opening sensor 3 for detecting the throttle opening θth is connected to the rotary shaft of the throttle valve.

The engine is equipped with a cooling water temperature sensor 4 for detecting the cooling water temperature Tw and a crank pulse which is arranged in the vicinity of the crankshaft 55 to calculate the engine speed Ne and to execute crank interrupt processing for each stage. It is provided with a crank pulser 2A which is generated and a cam pulser 54 which is arranged in the vicinity of the cam shaft 53 for operating the intake and exhaust valves and which generates (or calculates) a TDC pulse.

The ECU (electronic control unit) 60 receives the output signals of the respective sensors and pulses, and further, the atmospheric pressure Pa output from the atmospheric pressure sensor 5 and the voltage of the battery 8 (battery voltage Vb). Is entered. The ECU 60 includes a microcomputer, calculates a fuel injection amount Tout by a method described later, and
Is used to control the injector 29.

Although not directly related to the present invention, the ECU 60 controls the fuel pump 52 provided in the fuel tank 51 and the opening control of the intake duct 57 provided in the air cleaner 56.

Next, the operation of the embodiment of the present invention will be described in detail with reference to FIG. This process is executed by an interruption by a crank pulse in a predetermined stage. In addition,
The contents of various symbols used in the following description are as follows.

Tout: Fuel injection amount Tim: Basic injection amount Ktotal: First basic injection amount correction coefficient Ktw: First water temperature correction coefficient Kta: Intake air temperature correction coefficient Kpa: Atmospheric pressure correction coefficient Kast: Second basic injection amount correction coefficient Tacc: Acceleration increase value Kacc: Acceleration increase value correction coefficient Ktwt: Second water temperature correction coefficient Tv: Voltage increase value Fuel injection amount Tout is roughly the basic injection amount Tim and the acceleration increase value as shown in FIG. The basic injection amount Tim is calculated from Tacc and the voltage increase value Tv, and the basic injection amount Tim is the first basic injection amount correction coefficient Ktotal and the second basic injection amount correction coefficient K.
ast and the acceleration boost value Tacc are corrected using the acceleration boost value correction coefficient Kacc. Further, the first basic injection amount correction coefficient Ktotal is calculated using the first water temperature correction coefficient Ktw, the intake air temperature correction coefficient Kta, and the atmospheric pressure correction coefficient Kpa, and the acceleration increase value correction coefficient Kacc.
Is calculated using the second water temperature correction coefficient Ktwt and the Kta and Kpa. Intake temperature correction coefficient Kta
Is calculated from the Kta1 table or the Kta2 table according to the load state of the engine. Similarly, the first water temperature correction coefficient Ktw is also calculated from the Ktw1 table or the Ktw2 table according to the load state.

First, in step S1 of FIG. 3, the first water temperature correction coefficient Ktw and the second water temperature correction coefficient Ktwt.
Is calculated. Specifically, the lines Ktw1 (Ktw1 table) and Ktw2 (Ktw) shown by the solid lines in FIG. 5 depend on whether the engine is in a low load state or a high load state.
tw2 table) one is selected and the cooling water temperature at that time T
The data of Ktw1 or Ktw2 read according to w is
The first water temperature correction coefficient Ktw is set. In addition, from the line Ktwt (Ktwt table) shown by the dashed line in the figure,
The data read according to the cooling water temperature Tw is set to the second water temperature correction coefficient Ktwt.

As is clear from FIG. 5, the lines Ktw1, Ktw2, and Ktwt are set such that their numerical values decrease as Tw increases, but in this example, the slope of the line Ktwt is further reduced. And the inclination of Ktw2 is set larger.

The selection of Ktw1 or Ktw2 according to the load state can be performed by the procedure of FIG. 6, for example. That is, first, at step S21, the engine speed Ne
Is determined to be equal to or less than a predetermined rotation speed Ne1, and Ne1
If it exceeds, it is determined that it is in a high load state,
In step S24, the line Ktw2 is selected, and the data read from the line according to the cooling water temperature Tw is
The first water temperature correction coefficient Ktw is set.

If Ne is less than Ne1, it is determined in step S22 whether the throttle opening θth is less than the predetermined opening θth1. If it exceeds θth1, it is determined that the load is high. Then, the processing is step S2.
Go to 4. When θth is equal to or less than θth1, it is determined that the load is low, the line Ktw1 is selected in step S23, and the data read from the line according to Tw is set to Ktw.

Returning to FIG. 3, the intake air temperature correction coefficient Kta is calculated in step S2. Specifically, depending on whether the engine is in a low load state or a high load state,
Lines Kta1 (Kta1 table) and K shown in FIG.
One of ta2 (Ktw2 table) is selected, and the data of Kta1 or Kta2 read according to the intake air temperature Ta at that time is set to the intake temperature correction coefficient Kta.

The lines Kta1 and Kta shown in FIG.
2 is common when the intake air temperature Ta is about 50 [° C] or less,
The line Kta2 has a fixed value when the temperature is exceeded. Of course, when the temperature exceeds the temperature, the slope of the line Kta2 may not be set to a fixed value and may be set to be gentler than the slope of the line Kta1.

Further, Kta1 or Kta2 depending on the load condition
Can be selected, for example, by the procedure shown in FIG.
Since the details of this processing are apparent from the description of FIG. 6, the description thereof will be omitted.

Returning to FIG. 3, the atmospheric pressure correction coefficient Kpa is calculated in step S3. This calculation is based on the table (Kpa table) shown in FIG.
Is required according to.

In step S4, the first equation is used to calculate the first
The basic injection amount correction coefficient Ktotal is calculated.

Ktotal = Ktw × Kta × Kpa (1) In step S5, the acceleration increase value correction coefficient Kacc is calculated from the second equation.

Kacc = Ktwt × Kta × Kpa (2) In step S6, the second basic injection amount correction coefficient Kas
t is calculated. This calculation is obtained from the table (Kast table) as shown in FIG. 10 according to the total number of TDC pulses accumulated from the start of the operation of the engine.

In step S7, the basic injection amount Tim is calculated. Specifically, according to the throttle opening θth and the engine speed Ne, Ne-θth shown in FIG.
One of the map and the Ne-Pb map shown in FIG. 12 is selected, and the basic injection amount Tim is read from the selected map in accordance with Ne and θth or the intake pressure Pb. The selection of each map is performed using the area selection table as shown in FIG.

The magnitude relation shown on the intake pressure Pb axis in the Ne-Pb map shown in FIG.
When b is an absolute pressure, and when the intake pressure Pb is a negative pressure, the magnitude relation is reversed.

In step S8, the basic injection amount Tim calculated as described above is corrected using the third equation.

Tim = Tim × Kast × Ktotal (3) In step S9, the acceleration increase value Tacc is set. This Tacc is a fixed value, for example. As described above, this process is executed by interruption by the crank pulse, but the predetermined number of times of execution of the process is set as one unit, and within this unit, the acceleration increase value Tacc is set to the acceleration of the vehicle. The number of times may be set to the fixed value, and the remaining number (the number of times that Tacc is set to the fixed value from the number of one unit) may be set to Tacc.

Of course, the value of the acceleration increase value Tacc itself may be set according to the acceleration of the vehicle.

In step S10, the acceleration increase value Tacc set as described above is corrected using the fourth equation.

Tacc = Tacc × Kacc (4) Then, in step S11, the fuel injection amount Tout is calculated from the fifth equation.

Tout = Tim + Tacc + Tv (5) Here, Tim and Tacc are the values corrected in steps S8 and S10, respectively. In addition, the voltage increase value T
v is obtained from the table (Tv table) shown in FIG. 14 according to the battery voltage Vb. The voltage increase value Tv is calculated, for example, in another process (not shown) executed at regular time intervals.

In FIG. 14, the unit of the voltage increase value Tv on the vertical axis is time, but this is the energization time of the injector 29 and corresponds to the fuel injection amount.

The fuel injection amount Tou calculated in this way
t is output to the drive circuit of the injector 29,
The energization time (or energization duty ratio) of the injector 29 is controlled according to t.

The intake air temperature Ta, the engine speed Ne, the throttle opening θth, the cooling water temperature Tw, and the atmospheric pressure P are as described above.
a and the intake pressure Pb are determined by the interrupt processing by the crank pulse or the processing executed at regular time intervals.
It is detected and calculated by a known method.

FIG. 15 is a functional block diagram of an embodiment of the present invention, and FIG. 16 is a functional block diagram showing details of the load determining means 9 of FIG. In FIG. 15, the engine speed sensor 2 has a function of the crank pulser 2A (FIG. 2),
And the function of determining the engine speed Ne by using the pulse output from the pulser 2A. In addition, the TDC pulser 6 includes a crank pulser 2A and a cam pulser 5
4 shows a function of outputting a TDC pulse using the output pulse of FIG. 4 (FIG. 2) or the like.

First, in FIG. 15, the load determining means 9
The load state of the engine is detected using the engine speed Ne and the throttle opening θth. More specifically, as shown in FIG. 16, the comparison means 30 compares Ne and the predetermined rotation speed Ne1 stored in the Ne1 storage means 31, and Ne is Ne1.
If it exceeds, it is determined that the load is high, and the Kta2 table 12 and the Ktw2 table 14 are selected via the OR gate 34. Further, the comparison means 32 compares the θth and the predetermined opening degree θth1 stored in the θth1 storage means 33, and when θth exceeds θth1, it is determined that the load is also high, and the Kta2 table is determined via the OR gate 34. 12 and Ktw2 table 14 are selected. When the comparing means 30 and 32 do not judge the high load, the Kta1 table 11 and Ktw1 are supplied via the AND gate 35.
The table 13 is selected.

Returning to FIG. 15, Kta1 or Kta2 corresponding to the intake air temperature Ta is read from the selected Kta1 table 11 or Kta2 table 12, and this is set in Kta. Also selected Ktw1 table 13 or Ktw
2 From Table 14, Ktw1 corresponding to the cooling water temperature Tw
Or Ktw2 is read and set to Ktw.

Further, Ktwt corresponding to Tw is read out from the Ktwt table 16, and Kpa corresponding to atmospheric pressure Pa is read out from the Kpa table 17, respectively.

The Ktotal setting means 15 uses Ktw and K
Each of ta and Kpa is multiplied to calculate the first basic injection amount correction coefficient Ktotal. Further, the Kacc setting means 18 uses Ktw
t and Kta and Kpa are respectively multiplied to calculate the acceleration increase value correction coefficient Kacc.

The selecting means 10 uses the engine speed Ne and the throttle opening θth to establish the Ne-θth map 23 (FIG. 11) and Ne-Pb in the relationship shown in FIG.
Select one of the maps 24 (FIG. 12). And Ne
When the −θth map 23 is selected, the basic injection amount Tim is read according to Ne and θth, and when the Ne-Pb map 24 is selected, Tim is read according to Ne and the intake pressure Pb. ..

The TDC pulse output from the TDC pulser 6 is input to the counter 21, and the total number of pulses is counted. The counted TDC pulse number is input to the Kast table 22 (FIG. 10), and the second basic injection amount correction coefficient Kast corresponding to the pulse number is read.

The Tim correcting means 25 adds Ktotal and K to the basic injection amount Tim read from the map 23 or 24.
Modify Tim by multiplying ast.

The Tacc correction means 20 is the Tacc storage means 1
The acceleration increase value Tacc is read from 9, and the Tacc is corrected by multiplying the Tacc with the acceleration increase value correction coefficient Kacc.

From the Tv table 26, the battery voltage V
The voltage increase value Tv is read according to b.

Then, the Tout setting means 27 sets the fuel injection amount Tout by adding the corrected basic injection amount Tim and the acceleration increase value Tacc and the voltage increase value Tv.
The fuel injection amount Tout calculated in this way is output to the injector drive circuit 28.

Now, FIG. 15 described above is simplified and shown in FIG. FIG. 1 is a functional block diagram of the present invention. In the figure, the same reference numerals as those in FIG. 15 represent the same or equivalent portions. As described with reference to FIG. 15, the intake air temperature correction coefficient Kta is set according to the intake air temperature Ta, but is set to a different value depending on whether the engine has a low load or a high load. That is, when the load is low, the intake temperature correction coefficient setting means 11A (Kta1 table 1 at low load) is used.
1) is selected, and when the load is high, the high load intake temperature correction coefficient setting means 12A (Kta2 table 12) is selected.

Each of the setting means 11A or 12A sets Kta1 or Kta2 according to the intake air temperature Ta and outputs it to the fuel injection amount calculation means 100 as an intake air temperature correction coefficient Kta. The fuel injection amount calculation means 100 uses the input intake air temperature correction coefficient Kta to calculate the fuel injection amount to be output to the injector drive circuit 28 by an appropriate method.

That is, first, the basic injection amount correction coefficient setting means 15A and the acceleration increase value correction coefficient setting means 18A set the basic injection amount correction coefficient and the acceleration increase value correction coefficient using the intake air temperature correction coefficient Kta. The basic injection amount setting means 23A sets the basic injection amount Tim using the engine speed Ne, the intake pressure Pb, the throttle opening θth, etc., and the acceleration increase value setting means 19A sets the acceleration increase value Tacc.

The basic injection amount correction means 25A and the acceleration increase value correction means 20A are respectively composed of setting means 15A and 18A.
Using the basic injection amount correction coefficient and the acceleration increase value correction coefficient set in step 1, the basic injection amount Tim and the acceleration increase value Tacc are used.
To fix. Then, the fuel injection amount setting means 27A determines the fuel injection amount Tout using the corrected Tim and Tacc.

The load state determination process for table selection shown in FIG. 8 can also be performed using the method shown in FIG. That is, when the clutch is in the off state, or when the transmission of the vehicle is in the neutral state (affirmative determination in step S31a, no-load switch on), the low load is determined, and when the clutch and the transmission are not in the above states. The high load may be determined (negative determination in step S31a, no-load switch off). The above no-load switch can be achieved by the function of the microcomputer of the ECU 60. This load state determination method can also be applied to the table selection in FIG.

Although the present invention has been described by being applied to a motorcycle, the present invention is not particularly limited to this.
Needless to say, it may be applied to a fuel injection control device for an internal combustion engine such as an automobile.

[0057]

As is apparent from the above description, according to the present invention, when the detected intake air temperature is high during the high load operation, the intake air temperature correction coefficient which is less influenced by the intake air temperature is set. That is, even if the detected intake air temperature is higher than the actual intake air temperature, it is possible to set an intake air temperature correction coefficient that is about the actual intake air temperature and is less affected by the intake air temperature. Therefore, even during high load operation, the fuel injection amount according to the engine request can be obtained.

[Brief description of drawings]

FIG. 1 is a functional block diagram of the present invention.

FIG. 2 is a block diagram of an embodiment of the present invention.

FIG. 3 is a flowchart showing the operation of one embodiment of the present invention.

FIG. 4 shows the contents of various symbols used to describe the present invention,
FIG. 3 is a diagram showing a schematic process of the steps up to calculation of a fuel injection amount Tout.

FIG. 5 is a graph showing an example of the contents of a Ktw1 table, a Ktw2 table, and a Ktwt table.

FIG. 6 is a flowchart showing an example of a processing operation for selecting one of a Ktw1 table and a Ktw2 table.

FIG. 7 is a graph showing an example of the contents of a Kta1 table and a Kta2 table.

FIG. 8 is a flowchart showing an example of a processing operation for selecting one of the Kta1 table and the Kta2 table.

FIG. 9 is a graph showing an example of the contents of the Kpa table.

FIG. 10 is a graph showing an example of the contents of a Kast table.

FIG. 11 is a graph showing an example of the contents of the Ne-θth map.

FIG. 12 is a graph showing an example of the contents of an Ne-Pb map.

FIG. 13 is a graph showing the relationship between the throttle opening θth and the engine speed Ne for selecting one of the Ne-θth map and the Ne-Pb map.

FIG. 14 is a graph showing an example of the contents of the Tv table.

FIG. 15 is a functional block diagram of an example of the present invention.

16 is a functional block diagram showing details of the load determining means in FIG.

FIG. 17 is a flowchart showing another example of the processing operation for selecting one of the Kta1 table and the Kta2 table.

[Explanation of symbols]

1 ... Intake temperature sensor, 2 ... Engine speed sensor, 3 ... Throttle opening sensor, 7 ... Intake pressure sensor, 9 ... Load determination means, 11 ... Kta1 table, 11A ... Low load intake temperature correction coefficient setting means, 12 ... Kta2 table, 12A ... High intake air temperature correction coefficient setting means, 15A ... Basic injection amount correction coefficient setting means, 18A ... Acceleration increase value correction coefficient setting means, 19A ... Acceleration increase value setting means, 20A ... Acceleration increase value correction Means, 23A ... Basic injection amount setting means, 25A ... Basic injection amount correcting means, 27A ... Fuel injection amount setting means, 28 ...
Injector drive circuit, 29 ... Injector

Continuation of the front page (51) Int.Cl. ⁵ Identification number Office reference number FI technical display location F02D 45/00 370 Z 8109-3G

Claims (2)

[Claims] 1. A fuel injection control device for an internal combustion engine, which calculates a fuel injection amount according to intake air temperature, wherein: load determining means for detecting a load state of the internal combustion engine; and intake air temperature when the internal combustion engine has a high load. High-load intake-air temperature correction coefficient setting means for setting the intake-air temperature correction coefficient according to the low-load intake-air temperature correction coefficient for setting the intake-air temperature correction coefficient according to the intake-air temperature when the internal combustion engine has a low load. And a fuel injection amount calculation unit for calculating a fuel injection amount using the intake air temperature correction coefficient set by each of the setting units. The intake air temperature correction coefficient is set so that the value decreases as the intake air temperature rises, and the high load intake air temperature correction coefficient setting means sets the low intake air temperature correction coefficient until the intake air temperature reaches a predetermined intake air temperature. With almost the same characteristics as the coefficient setting means A fuel for an internal combustion engine, wherein an intake air temperature correction coefficient is set, and after the intake air temperature exceeds the predetermined intake air temperature, a decrease in the intake air temperature correction coefficient is suppressed by the intake air temperature correction coefficient setting means during low load. Injection control device. 2. The internal combustion engine according to claim 1, wherein the high-load intake air temperature correction coefficient setting means sets the intake air temperature correction coefficient to a fixed value after the intake air temperature exceeds the predetermined intake air temperature. Engine fuel injection control device.