JPH02211340A - Correction for fuel quantity in internal combustion engine - Google Patents

Abstract

PURPOSE:To effectively improve the emission in the opening and closing of an EGR valve by constituting the title device so that the fuel injection quantity supplied from a fuel injection valve is gradually increased or decreased before and after the time when the differential pressure between the atmospheric pressure and the intake pressure reaches the operation pressure of the EGR valve. CONSTITUTION:When an EGR valve 9 changes from the perfectly opened state to the perfectly closed state, or changes from the perfectly closed state to the perfectly opened state, the fuel supply quantity is increased gradually, as the recirculation quantity of exhaust gas is throttled, and as the recirculation quantity of the exhaust gas increases, the fuel supply quantity is gradually throttled. Therefore, when the EGR valve 9 is opened or closed, the switching of the air-fuel ratio from lean to rich or from rich to lean in the front half and in the rear half can be surely suppressed. Therefore, the disturbance of the air-fuel ratio in the opening and closing of the EGR valve 9 can be effectively reduced, and the removal efficiency for the harmful components in the exhaust gas in these regions can be improved effective.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a fuel temperature correction method for an internal combustion engine equipped with an electronically controlled fuel injection device, an exhaust gas recirculation device, etc. used in automobiles and the like.

BACKGROUND OF THE INVENTION [0003] Engines of automobiles and the like are usually equipped with an exhaust gas recirculation device including an EGR valve and the like.

Then, the EGR valve is opened at appropriate times, except when the engine is cold or under high load, to recirculate part of the exhaust gas to the intake system, thereby reducing the generation of NO8. .

Furthermore, some engines equipped with electronically controlled fuel injection devices use the required injection amount during exhaust gas recirculation as the basic injection amount when determining the amount of fuel to be injected from the fuel injection valve. However, the EGR valve, which is configured to operate based on the differential pressure between atmospheric pressure and intake pressure, has problems when the intake pressure is close to atmospheric pressure and a sufficient differential pressure that exceeds the operating pressure does not occur between the intake pressure and the atmospheric pressure. Therefore, it is necessary to correct the fuel injection amount in such a region. Therefore, as prior art of the present invention, for example, Japanese Patent Application Laid-Open No. 60-17334
As shown in Publication No. 3, when the exhaust gas is not recirculated,
There is an example in which the amount of fuel injected from a fuel injection valve is increased compared to when exhaust gas is recirculated. As shown in Figure 4, a specific method for increasing or decreasing the fuel injection amount is to correct it depending on whether the difference between atmospheric pressure and intake pressure exceeds the EGR valve operating pressure (for example, 100 mmHg). There is a method of increasing/decreasing the fuel injection amount by increasing/decreasing the coefficient.

[Problems to be Solved by the Invention] However, the EGR valve does not instantaneously become fully open or fully open when a certain pressure is reached, but fully closes or fully opens with a certain width and characteristics. Specifically, as shown in FIG. 5, when the EGR valve changes from a fully open state to a fully closed state, or from a fully closed state to a fully open state, the EGR valve changes smoothly with respect to changes in the intake pressure. Therefore, the EGR valve operating pressure is usually approximately halfway between when the EGR valve begins to close and when it becomes fully open, or from when it begins to open until it becomes fully open. Therefore, according to the conventional method of increasing or decreasing the fuel injection amount in skips using this operating pressure as a guide, the amount of recirculation of exhaust gas is throttled from the time the EGR valve begins to close until it reaches the intermediate position, so the air-fuel ratio A/F becomes lean. On the other hand, although the exhaust gas is still being recirculated to the intake system even after passing the intermediate position, the fuel injection amount is suddenly increased after this intermediate position, so in this region the air-fuel ratio A/P increases. Become rich. Since such a malfunction is repeated each time the EGR valve is opened or closed, the air-fuel ratio becomes unstable, causing deterioration of emissions and the like.

The present invention aims to eliminate such problems.

[Means for Solving the Problems] In order to achieve the above object, the present invention employs the following configuration. That is, the fuel correction method for an internal combustion engine according to the present invention includes a fuel injection valve that supplies fuel to an intake system, and an EGR valve that is operated by a pressure difference between atmospheric pressure and intake pressure, and a fuel injection valve that supplies fuel to an intake system. A fuel correction method for an internal combustion engine, which increases the amount of fuel injected from the fuel injection valve when exhaust gas is not recirculating to the intake system, the method comprising: increasing the amount of fuel injected from the fuel injection valve before and after the differential pressure reaches the operating pressure of the EGR valve; The present invention is characterized in that the amount of fuel injected from the fuel injection valve is gradually increased or decreased.

[Function] When the EGR valve opens or closes, the operating pressure is set approximately in the middle and changes smoothly with respect to the intake pressure.Using these characteristics when determining the fuel injection amount will result in effective fuel injection. Correction becomes possible.

That is, according to the above-mentioned configuration, when the EGR valve starts to close from the fully open state, the amount of fuel injection (■) is gradually increased accordingly, and when the EGR valve becomes fully open,
This will stop increasing the amount of fuel injection m.

On the other hand, when the EGR valve starts to open, the fuel injection amount is gradually reduced accordingly, and when the EGR valve is fully opened, the reduction in the fuel injection amount is stopped.

[Example] Hereinafter, an example of the present invention will be described with reference to FIGS. 1 to 3.

An engine 1, which is an internal combustion engine shown in the drawing, is used in an automobile, and includes a fuel injection valve 2 that injects fuel into an intake system, and an exhaust gas recirculation device 3 that recirculates a part of exhaust gas to the intake system. It is equipped with

The fuel injection valve 2 is attached to the intake pipe 4 and has an electromagnetic coil inside. When a fuel injection signal a is applied to the electromagnetic coil from the electronic control device 5, the fuel in the dish corresponding to the fuel injection signal a is injected into the vicinity of the intake port.

The exhaust gas recirculation device 3 includes an EGR valve 9 interposed in an exhaust gas recirculation passage 8 that communicates an exhaust passage 6 and an intake passage 7.
The opening and closing of this EGR valve 9 is controlled by the electronic control device 5 via the first negative pressure switching valve 10 and the like.

The EGR valve 9 has an internal space divided into a negative pressure chamber and an atmospheric pressure chamber by a diaphragm.
Intake pressure is introduced through a modulator 11 (negative pressure regulating valve), so that atmospheric pressure is always introduced into the atmospheric pressure chamber. Then, the differential pressure between the atmospheric pressure and the intake pressure is the operating pressure of the EGR valve 9 (for example, 100 mmH
The exhaust gas recirculation passage 8 is opened and closed before and after reaching point g).

The first negative pressure switching valve 10 is a vacuum switching type three-way switching valve, and the first port 10a communicates with the EGR boat 13 opened upstream of the throttle valve 12, and the second port 10b communicates with the inside of the air cleaner 14. is connected to. Further, the third port 10c communicates with the negative pressure chamber of the EGR valve 9 via the EGR modulator 11.

When the electrical input terminal is not energized, it is held at the intake pressure side and the first port 10a and the third port 10c are electrically connected, and when the electrical input terminal is energized, The second port 10b is held on the atmospheric pressure side.
and the third port 10c are electrically connected.

Further, a pressure sensor 16 is provided in the intake system of the engine 1 via a second negative pressure switching valve 15. The second negative pressure switching valve 15 is a vacuum switching type three-way switching valve similar to the first negative pressure switching valve 10, and the first port 15a communicates with the inside of the surge tank 18 via the gas filter 17. The second port 15b is connected to the air cleaner 1.
It communicates with 4. Further, a third port 15c communicates with the inside of the pressure sensor 16. When the electrical input terminal is not energized, it is held at the intake pressure side and the first port 15a and the third port 15c communicate with each other, and when the electrical input terminal is energized, The second port 15b and the third port 15 are held on the atmospheric pressure side.
c is connected.

The electronic control device 5 is composed of a microcomputer unit equipped with a central processing unit 19, a memory 20, an input interface 21, and an output interface 22. An intake pressure signal C, an atmospheric pressure signal C, an engine rotation signal from a crank angle sensor (not shown), and the like are respectively input.

On the other hand, from the output interface 22, a control signal d to the first negative pressure switching valve 10, a control signal e to the second negative pressure switching valve 15, a fuel injection signal a to the fuel injection valve 2, etc. Each is output.

Further, this electronic control device 5 has a built-in program as schematically shown in FIG. 2, and the program is repeatedly executed every predetermined engine rotation. First, in step 51, the second negative pressure switching valve 15 is energized and the atmospheric pressure PA value is read from the pressure sensor 16.
Proceed to step 52. In step 52, the energization to the second negative pressure switching valve 15 is stopped, the intake pressure PMTP value is read from the pressure sensor 16, and the process proceeds to step 53. Step 5
In step 3, the basic injection ff1TPBsE is calculated according to the intake air cycle calculated from the intake pressure signal, engine rotation signal, etc., and then the process proceeds to step 54. In step 54, the correction coefficient PTPEGRO determined depending on the load is set in Table-1.
Search from. In other words, depending on the load, there are regions where exhaust gas recirculation is easy to be performed smoothly and regions where it is difficult to do so (low load), so this correction coefficient I'TPEGRO is
Correction is performed in this area by changing it in accordance with the TP value.

Table-1 Also, search Table-2 for the correction coefficient KTPEGR that is gradually changed before and after the differential pressure between the atmospheric pressure PA and the intake pressure PMTP reaches the operating pressure of the EGR valve 9 (for example, 100 mmHg). . This correction coefficient KTPEGR is
The opening degree is changed approximately in inverse proportion to the opening degree in the region where the EGR valve 9 opens and closes. Then, as schematically shown in Fig. 3, etc., within a certain range from the reference value (PA-125 mml 1 g) set near the operating pressure of the EGR valve 9, it gradually changes in response to changes in the intake pressure PMTP. That's how it is.

Table 2 And these correction coefficients FTPEGRO, KTPEG
Value multiplied by R FTPEGROx KTPEGRI:
: Add 1 to determine the EGR correction coefficient FTPEGR, and proceed to step 55.

In step 55, EGR is added to the basic injection amount TPBsE.
In addition to multiplying by the correction coefficient FTPEGR, the value is corrected by various other correction coefficients determined depending on the engine situation,
The fuel injection 1TAll actually supplied from the fuel injection valve 2 to the combustion chamber 23 is determined.

According to such a configuration, when the engine 1 is in a cold state or an idling state, or in a high load range, the first negative pressure switching valve 10 is energized from the electronic control device 5,
The second port 10b and the third port 10c are electrically connected. When the second photo port 10b and the third port 10c are electrically connected, atmospheric pressure acts on the negative pressure chamber of the EGR valve 9, so the EGR valve 9 closes the exhaust gas recirculation passage 8 and prohibits exhaust gas recirculation. be done.

On the other hand, in the exhaust gas recirculation execution region, the first negative pressure switching valve 10 is de-energized, and the pressure sensor 16 detects atmospheric pressure PA and intake pressure by port switching control of the second negative pressure switching valve 15. Each PMTP is detected. When the differential pressure between the atmospheric pressure PA and the intake pressure PMTP exceeds the operating pressure of the EGR valve 9 and the EGR valve 9 is fully open, a portion of the exhaust gas is transferred to the intake via the exhaust recirculation passage 8. It is refluxed to the passage 7. In this case, the basic injection amount TPBSH will not be increased by the EGR correction coefficient FTPEGR.

On the other hand, when the differential pressure between the atmospheric pressure PA and the intake pressure PMTP is lower than the operating pressure of the EGR valve 9 and the EGR valve 9 is in the fully closed state, the exhaust gas is not recirculated, so the E
The basic injection amount TPO8 is determined by the GR correction coefficient PTPEGR.
E is corrected by increasing the amount.

Then, from the fully open state of the EGR valve 9, the intake pressure P)iT
P changes to the atmospheric pressure PA side, and the differential pressure with atmospheric pressure PA becomes EG
When the operating pressure of the R valve 9 is lowered, in other words, when the EGR valve 9 changes from a fully open state to a fully closed state, the EGR correction coefficient FTPEGR gradually increases in substantially inverse proportion to the opening degree. That is, as the amount of recirculation of exhaust gas is gradually reduced, the basic injection fiTPBSE is gradually increased by m, so that the fuel injection 1T supplied from the fuel injection valve 2
AU will gradually increase. Then, the increase in amount is stopped when the EGR valve 9 is fully closed.

In addition, the intake pressure PHTP changes from the fully closed state of the EGR valve 9 to the vacuum side, and the pressure difference between the EGR valve 9 and the atmospheric pressure PA increases.
In other words, when the EGR valve 9 changes from a fully closed state to a fully open state, the EGR correction coefficient FTPEGR gradually decreases. That is, as the amount of exhaust gas recirculation increases, the basic injection ff1TPB
Since the increase correction amount of sH gradually decreases, the fuel injection valve 2
1 TAU of fuel is gradually throttled. The weight loss is achieved when the EGR valve 9 is fully opened.
It will be suspended.

Therefore, according to such a configuration, the EGR valve 9
When switches from fully open state to fully open state.

Alternatively, when switching from a fully closed state to a fully open state, the amount of fuel supplied is gradually increased as the exhaust gas recirculation n is throttled, and the amount of fuel supplied is gradually increased as the amount of exhaust gas recirculated increases. Therefore, when the EGR valve 9 is opened and closed, it is possible to reliably suppress the air-fuel ratio from switching to lean or rich in the first half and the second half. As a result, disturbances in the air-fuel ratio when the EGR valve 9 is opened and closed can be effectively reduced, so that the removal efficiency of harmful components from the exhaust gas in this region can be effectively increased.

When the EGR valve 9 is fully open or fully closed, the fuel injection amount TAU supplied from the fuel injection valve 2 is adjusted according to each situation, so that harmful components are not generated in these areas. can be effectively suppressed.

Moreover, the atmospheric pressure PA detected by the pressure sensor 16
Since the differential pressure between the intake pressure PMTP and the intake pressure PMTP is a relative pressure, the above control can be performed effectively even if the atmospheric pressure PA changes.

Incidentally, if the correction coefficient for increasing or decreasing the fuel injection amount when the EGR valve is opened or closed is changed by even smaller values, it becomes possible to perform fuel correction more accurately.

Further, in this embodiment, the correction coefficient is changed approximately linearly (proportional) in correspondence with the opening/closing characteristics of the EGR valve, but the correction coefficient is not necessarily changed in this way. Of course. For example, if the EGR valve does not change by a constant value at approximately the same speed, or if the speed of change differs depending on the load, if the EGR valve changes in a curved manner in accordance with the change mode, the amount of recirculation of exhaust gas can be changed. The amount of fuel injection can be finely adjusted.

[Effects of the Invention] According to the present invention configured as described above, the fuel supply amount can be finely adjusted in accordance with the amount of exhaust gas recirculated when the EGE valve opens and closes.
Disturbances in the air-fuel ratio when opening and closing the valve can be effectively suppressed. As a result, the E
It is possible to provide a fuel correction method for an internal combustion engine with excellent control accuracy that can effectively improve emissions when the GR valve opens and closes.

[Brief explanation of the drawing]

Figures 1 to 3 show one embodiment of the present invention, with Figure 1 being a schematic overall configuration diagram, Figure 2 being a flowchart showing the control procedure, and Figure 3 being a diagram showing control setting conditions. be. Fourth
The figure is a diagram corresponding to FIG. 3 showing a conventional example, and FIG. 5 is a diagram showing problems in the conventional example. 1... Internal combustion engine (automobile engine) 2... Fuel injection valve 3... Exhaust gas recirculation device 5... Electronic control device 6... Exhaust passage 7... Intake passage 8...・Exhaust recirculation passage 9...EGR valve

Claims (1)

[Claims] This E
A fuel correction method for an internal combustion engine in which the amount of fuel injected from the fuel injection valve is increased when exhaust gas is not recirculated to the intake system via the GR valve, the differential pressure causing the operation of the EGR valve. 1. A fuel correction method for an internal combustion engine, characterized in that the amount of fuel injected from the fuel injection valve is gradually increased or decreased before and after reaching the pressure.