JPH02199241A - Correcting method for air-fuel ratio at transition time - Google Patents

Abstract

PURPOSE:To properly regulate an air-fuel ratio in response to transition conditions by making up a transition time air-fuel ratio correction factor out of the first and second transition time air-fuel ratio correction factor, and thereby making detecting time intervals of the variation mutually different, which is the decisive element for said correction factor. CONSTITUTION:An electronic control device 4 sets up the first and second transition time air-fuel ratio correction factor based on intake air pressure detected by a pressure sensor 9. In this case, the first transition time air-fuel ratio correction factor is determined based on the variation of intake air pressure every short time, being instantly determined in response to the variation of it even if intake air pressure is changed comparatively to a great extent. On the other hand, the second transition time air-fuel ratio correction factor is determined based on the variation of intake air pressure detected by time intervals longer than the first factor, the minute variation of it being reflected. Then, a transition time air-fuel ratio correction factor is set up based on both of the first and second factor, the basic quantity of fuel injection being corrected, the quantity of fuel injection at the transition time being regulated so that a fuel injection valve 3 is actuated. Thus air-fuel ratio control is thereby executed in response to transition conditions.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a transient air-fuel ratio correction method employed in an engine of an automobile or the like equipped with an electronically controlled fuel injection device.

[Prior Art] In an electronically controlled fuel injection system configured to determine the basic injection amount based on engine speed, intake pressure, etc., in order to prevent adverse effects due to intake pulsation, etc., the intake pressure detected at regular intervals is used. It is common to use a smoothed version of the .

As schematically shown in FIG. 6, when the engine shifts to a transient state and the intake pressure changes, the transient air-fuel ratio correction coefficient is changed in accordance with the amount of change. Thus, when the transient air-fuel ratio correction coefficient changes, the fuel injection amount is corrected accordingly, and the air-fuel ratio of the air-fuel mixture supplied to the engine during the transient is adjusted. A specific prior art related to such a transient air-fuel ratio correction method is disclosed in, for example, Japanese Unexamined Patent Publication No. 144632/1983.

[Problems to be Solved by the Invention] However, in the conventional method, the transient air-fuel ratio correction coefficient is determined according to the amount of change in the intake pressure detected at regular intervals, so the intake pressure changes relatively gradually. If so, there is a problem in that it cannot be dealt with effectively. In other words, if the amount of change in intake pressure over a certain period of time is relatively large, the amount of change can be captured within the shortest amount of time.
Since the transient air-fuel ratio correction coefficient can be effectively changed in accordance with this, the responsiveness of fuel adjustment during transient times is improved. However, as schematically shown in Figure 7, if the amount of change in intake pressure is relatively small and is below the amount that can be detected at regular intervals, the amount of change cannot be detected, so transient The change cannot be reflected in the temporal air-fuel ratio correction coefficient. Therefore, as schematically shown in Figure 8, during transient operation where the change in intake pressure is relatively small (the diagram shows acceleration), the fuel injection amount is not adjusted by the transient air-fuel ratio correction coefficient, which is contrary to the situation. This tends to cause the air-fuel ratio to shift toward the lean side, resulting in poor emissions, drivability, etc.

Further, such a problem also occurs when the intake pressure changes gradually near the end of the transient period. For this reason,
When transitioning from acceleration to steady operation, there may be a lack of fuel in the intake pipe, which may cause deterioration in tracking performance.

The present invention aims to solve such problems.

[Means for Solving the Problems] In order to achieve the above object, the present invention determines a transient air-fuel ratio correction coefficient in accordance with the amount of change in intake pressure, and uses the transient air-fuel ratio correction coefficient to adjust the transient air-fuel ratio correction coefficient of the engine. In the transient air-fuel ratio correction method, the transient air-fuel ratio correction coefficient is configured by a first transient air-fuel ratio correction coefficient and a second transient air-fuel ratio correction coefficient, and The present invention is characterized in that the time intervals at which the amount of change, which is a determining factor, is detected are different from each other.

[Operation] According to such a configuration, when the first transient air-fuel ratio correction coefficient is determined based on, for example, the amount of change in the intake pressure every short time, when the intake pressure changes relatively largely, the amount of change is In response to this, the first transient air-fuel ratio correction coefficient is immediately determined.

On the other hand, if the amount of change in the intake pressure, which is the determining factor of the second transient air-fuel ratio correction coefficient, is detected at a time interval longer than the detection time when determining the first transient air-fuel ratio correction coefficient,
A minute change in intake pressure that cannot be reflected in the first transient air-fuel ratio correction coefficient can be reflected in the second transient air-fuel ratio correction coefficient.

When the transient air-fuel ratio correction coefficient is determined from the first and second transient air-fuel ratio correction coefficients, the basic injection amount is corrected based on the transient air-fuel ratio correction coefficient, and the transient fuel injection amount of the engine is adjusted. Therefore, during a transient period when the intake pressure change is large, the first transient air-fuel ratio correction coefficient is mainly reflected in the fuel injection amount, and during a transient period when the intake pressure change is relatively gradual or near the end of the transition period, the second transient air-fuel ratio correction coefficient is The temporal air-fuel ratio correction coefficient is reflected in the fuel injection amount.

[Embodiment] Hereinafter, an embodiment of the present invention will be described with reference to FIGS. 1 to 5.

The engine schematically shown in FIG. 1 is used in an automobile and is equipped with an electronically controlled fuel injection device 1. The engine shown schematically in FIG. The electronically controlled fuel injection device 1 includes a fuel injection valve 3 attached to an intake pipe 2 and an electronic control device 4 that controls the opening time of the fuel injection valve 3. Various information for adjusting the air-fuel ratio of the air-fuel mixture, etc. is input to the controller.

The fuel injection valve 3 has a built-in electromagnetic coil, and when a fuel injection signal a is applied from the electronic control device 4 to the electromagnetic coil, an amount of fuel corresponding to the application time of the fuel injection signal a is injected into the intake port. It is designed to be sprayed nearby.

The electronic control device 4 includes a central processing unit 5 and a memory 6.
, an input interface 7 , and an output interface 8 . The input interface 7 receives at least an intake pressure signal from a pressure sensor 9 and a crank angle sensor 10 .
The engine rotation signal C from the engine, engine cooling water temperature information, etc. are input. The pressure sensor 9 is
The intake pressure PM in the surge tank 11 can be detected, and the crank angle sensor 10 provided in the distributor 12 is configured to be able to detect the engine speed. On the other hand, the output interface 8 outputs a fuel injection signal a to the fuel injection valve 3.

Then, this electronic control device 4 calculates the amount of intake air from the intake pressure signal C, engine rotation signal C, etc., and adjusts the basic injection amount determined according to the intake air amount by various correction coefficients determined according to the engine situation. The fuel injection valve 3 is corrected by
It plays the role of adjusting the amount of fuel injected from the combustion chamber 13 to the combustion chamber 13.

For example, during engine transients, the transient air-fuel ratio correction coefficient FAEW is determined according to the amount of change in the intake pressure PM, and the basic injection amount is corrected using the transient air-fuel ratio correction coefficient FAEW to adjust the fuel injection amount. It's Nishide. The transient air-fuel ratio correction coefficient FAEW is a transient correction coefficient that is set to 0 when the engine is started, for a certain period of time after engine startup, and when the throttle valve 14 is in the idle position, and is set to 0 when the first transient air-fuel ratio Correction coefficient FAEWA
and the second transient air-fuel ratio correction coefficient FAEWB. The first transient air-fuel ratio correction coefficient FAEWA is determined by the amount of change in the intake pressure PM at relatively short intervals (for example, every ignition), and the second transient air-fuel ratio correction coefficient FAEWB is determined for a longer period. It is determined based on the amount of change in the intake pressure PM every time (for example, every 400 m5).

A program as schematically shown in FIG. 2 is set in this electronic control unit 4 in order to determine the above-mentioned transient air-fuel ratio correction coefficient FAEW. First, step 5
In step 1, after determining the amount of change ΔPM in the intake pressure PM from the difference between the latest intake pressure P M + detected for each ignition and the previous intake pressure P M , -0, the process proceeds to step 52 . In step 52, the predetermined correction value C1 and the water temperature correction value KT determined depending on the temperature of the engine cooling water are changed to the change amount Δ
P.M.

The first transient air-fuel ratio correction coefficient FAEWA is determined by multiplying by FAEWA, and the process proceeds to step 53. In step 53, the latest intake pressure PM and the intake pressure 400m5 ago P M l-4
The amount of change ΔPM2 in the intake pressure PM is determined from the difference from the difference from 00, and the process proceeds to step 54. In step 54, a predetermined correction value C
The second transient air-fuel ratio correction coefficient FAEWB is determined by multiplying the amount of change ΔPM2 by 2 and a water temperature correction value KT2 determined by the temperature of the engine coolant.

According to such a configuration, as schematically shown in FIG. 3, when the engine is in a transient state and the amount of change in the intake pressure PM at fixed time intervals is relatively large, the change in intake pressure PM is immediately performed according to the amount of change. A first transient air-fuel ratio correction coefficient FAEWA and a second transient air-fuel ratio correction coefficient FAEWB are determined, and the transient air-fuel ratio correction coefficient FAEW is determined by the sum of these. Then, this transient air-fuel ratio correction coefficient FAE
The basic injection amount is corrected by W, and the fuel injection amount actually supplied from the fuel injection valve 3 during engine transients is adjusted.

On the other hand, as schematically shown in FIG. 4, when the intake pressure PM changes relatively slowly during a transient period and the amount of change cannot be captured at each ignition interval, the first transient air-fuel ratio correction coefficient Although FAEWA becomes 0, the second transient air-fuel ratio correction coefficient FAEWB is effectively determined. That is, as mentioned above, even if the intake pressure PM changes slowly, if the intake pressure PM is detected at intervals longer than each ignition,
Since the amount of change can be reliably detected, the second transient air-fuel ratio correction coefficient FAEWB can be determined. Therefore, in such a case, the second transient air-fuel ratio correction coefficient FAEWB
substantially becomes the transient air-fuel ratio correction coefficient FAEW. Then, the basic injection amount is corrected by this transient air-fuel ratio correction coefficient FAEW, and the fuel injection amount actually supplied from the fuel injection valve 3 during engine transient is adjusted in accordance with load changes. Therefore, as shown in FIG. 5, disturbances in the air-fuel ratio A/F during transient operation with small changes in the intake pressure PM are suppressed.

Therefore, with this configuration, not only relatively large transient load changes, but also small load changes that are often overlooked by conventional methods can be reliably reflected in the fuel injection amount according to this embodiment. can be done. In other words, with this configuration, the fuel supply amount can be adjusted quickly and accurately according to transient conditions, which improves the ability of air-fuel ratio adjustment to follow changes in load, improving drivability, emissions, etc. during transient conditions. can definitely be improved.

In addition, in the above embodiment, the first transient air-fuel ratio correction coefficient and the second transient air-fuel ratio correction coefficient were added and used.
The one with a larger value may be used preferentially.

Further, in the above embodiment, the case was described when the engine was accelerating, but the method according to the present invention can also be effectively employed when the engine is decelerating.

[Effects of the Invention] According to the present invention having the above-described configuration, whether the intake pressure is changing rapidly or slowly, it can be adjusted appropriately according to each transient situation. The air-fuel ratio can be adjusted and the air-fuel ratio adjustment can follow load changes better, so it is possible to reliably improve drivability and emissions during transient periods.It has excellent control accuracy and responsiveness during transient periods. The present invention can provide an air-fuel ratio correction method.

[Brief explanation of the drawing]

1 to 5 show an embodiment of the present invention, FIG. 1 is a schematic overall configuration diagram, FIG. 2 is a flowchart showing the control procedure, and FIGS. 3 and 4 are operation explanatory diagrams. , FIG. 5 is a diagram showing an example of the effect. 6 to 8 show conventional examples, FIG. 6 is an operation explanatory diagram equivalent to FIG. 3, FIG. 7 is an operation explanatory diagram equivalent to FIG. This is a diagram equivalent to Figure 5. 1...Electronically controlled fuel injection device 3...Fuel injection valve 4...Electronic control device 9...Pressure sensor FAEW...Transient air-fuel ratio correction coefficient

Claims (1)

[Claims] In the transient air-fuel ratio correction method, the transient air-fuel ratio correction coefficient is determined in accordance with the amount of change in the intake pressure, and the transient air-fuel ratio correction coefficient adjusts the fuel injection amount during the engine transient. The temporal air-fuel ratio correction coefficient is configured by a first transient air-fuel ratio correction coefficient and a second transient air-fuel ratio correction coefficient, and the detection time intervals of the amount of change, which are determining factors thereof, are made different from each other. Air-fuel ratio correction method during transient periods.