JPH02119650A - Air-fuel ratio control method for transient period - Google Patents

Abstract

PURPOSE:To enhance the accuracy of controlling an air-fuel ratio to improve emission, etc. by permitting the state of an engine immediately before shifting to be reflected in subsequent fuel control when accelerated and decelerated states shift each other. CONSTITUTION:An electrically controlled fuel injection device 2 loaded on an engine 1 is provided with a fuel injection valve 4 loaded on an intake pipe 3, and an electronic control device 5 for controlling the fuel injection valve 4. The electronic control device 5 controls the fuel injection valve 4 based on each detection signal from various sensors 12, 14 for detecting the operating state of the engine 1. In this instance, when the engine 1 decelerates during controlling the fuel injection quantity to increase it, the remaining increased amount of fuel injection quantity is reflected in fuel control for decreasing, and the decreased amount of fuel for deceleration is increased. On the other hand, when the engine 1 accelerates during controlling the fuel injection quantity to decrease it, the remaining decreased amount of the fuel injection quantity is reflected in fuel control for acceleration, and the increased amount of fuel for acceleration is increased.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a transient air-fuel ratio control method that can be suitably employed in engines such as automobiles equipped with an electronically controlled fuel injection device.

[Prior Art] In this type of engine, as schematically shown in FIG.
When the engine shifts from a steady state to an accelerating state and the intake pressure increases, the fuel injection amount is accelerated and increased in response to the change in intake pressure, and the amount is increased to maintain the air-fuel ratio after the transition near the stoichiometric air-fuel ratio. I'm trying to make adjustments.

On the other hand, as schematically shown in Fig. 9, when the engine shifts from a steady state to a deceleration state and the intake pressure decreases, the fuel injection amount is decelerated and reduced in response to the change in intake pressure, and the A reduction adjustment is made to maintain the air-fuel ratio near the stoichiometric air-fuel ratio.

[Problems to be Solved by the Invention] However, according to such a configuration, as schematically shown in FIG. 10, while the engine shifts to an acceleration state and the fuel injection amount is adjusted to increase, When the engine shifts to a deceleration state and the intake pressure decreases, the fuel injection amount is adjusted to decrease accordingly. For this reason, due to the residual increase amount A immediately before the engine shifts to the deceleration state, the deceleration reduction in fuel will not be sufficiently performed. Moreover, when the engine shifts to an acceleration state, the inside of the intake pipe is in a wet state due to the accelerated increase in fuel, so when the engine shifts from this state to a deceleration state, the amount corresponding to the remaining increase A is Even more weight loss C is required. That is, according to such a configuration, when the engine shifts from an acceleration state to a deceleration state, an appropriate weight reduction adjustment according to the deceleration state is not performed. The fuel ratio A/F becomes overrich. For this reason, fuel consumption during deceleration is not sufficiently reduced, causing deterioration in emissions, drivability, and the like.

Further, as schematically shown in FIG. 11, if the engine shifts to an accelerating state and the intake pressure increases while the engine shifts to a decelerating state and the fuel injection amount is being reduced,
Accordingly, the fuel injection amount is adjusted to increase. Therefore, the remaining weight loss B just before the engine shifts to acceleration state
Due to such reasons, the acceleration increase in fuel becomes insufficient. Moreover,
When the engine shifts to a deceleration state, the inside of the intake pipe is almost dry due to deceleration loss of fuel, negative pressure, etc., so when the engine shifts from such a state to an acceleration state, the remaining region n B is reached. More volume increase than the corresponding output would be required. That is, according to the above-mentioned configuration, when the engine shifts from a deceleration state to an acceleration state, an appropriate increase adjustment according to the acceleration state is not performed, so as schematically shown in FIG. The air-fuel ratio A/F becomes lean.

This causes deterioration in emissions during acceleration, acceleration response, etc.

In order to deal with this problem, as a prior art of the present invention, for example, as shown in Japanese Patent Laid-Open No. 58-150033, when the engine is in an acceleration state and the fuel increase adjustment is being performed, , when the engine enters a deceleration state, the remaining amount of increase is cleared and the newly requested deceleration reduction is executed. Among them, when the engine shifts to an acceleration state, there is a system that clears the remaining reduction amount and executes a newly requested acceleration increase.

However, since the fuel situation in the intake pipe is different when the engine transitions from acceleration to deceleration and when it transitions from deceleration to acceleration, even with this configuration, it is possible to prevent the above-mentioned problems. difficult to resolve.

The present invention aims to solve the above problems all at once.

[Means for Solving the Problems] In order to achieve the above object, the present invention increases the fuel injection amount when the engine shifts to an acceleration state, and increases the fuel injection amount when the engine shifts to a deceleration state. In a transient air-fuel ratio control method configured to reduce the amount of
If the engine enters a deceleration state during the adjustment to increase the fuel injection amount, the remaining increase in the fuel injection amount is reflected in the reduction adjustment and the deceleration reduction amount is increased. The present invention is characterized in that when the vehicle enters an acceleration state, the remaining reduction in the fuel injection amount is reflected in the acceleration adjustment to increase the acceleration increase.

[Operation] According to such a configuration, when the engine shifts from a steady state to an acceleration state, the amount of fuel is increased for acceleration, and
The air-fuel ratio after the end of acceleration is adjusted, and when the engine shifts from a steady state to a deceleration state, the amount of fuel is reduced during deceleration, and the air-fuel ratio after the end of deceleration is adjusted.

Then, when the engine shifts to a deceleration state while the engine shifts to an acceleration state and the fuel injection amount is adjusted to increase, the amount of increase remaining immediately before the shift is reflected in the fuel reduction adjustment. In other words, when deceleration reduction of fuel is executed with the increased amount remaining, the deceleration reduction amount is increased by an even larger value than the remaining increased amount, and the fuel injection amount during deceleration becomes less than the amount corresponding to the intake pressure etc. will be further narrowed down.

Furthermore, if the engine shifts to an accelerating state while the engine is shifting to a decelerating state and the fuel injection amount is being adjusted to decrease, the remaining amount of fuel injection immediately before the transition is reflected in the fuel increase adjustment. In other words, when an accelerated fuel increase is executed from a state where a reduced amount remains, the accelerated increased amount is increased by an even larger value than the remaining reduced amount, and the fuel injection amount during acceleration becomes less than the amount corresponding to the intake pressure, etc. will be further increased.

[Example] Hereinafter, an example of the present invention will be described with reference to FIGS. 1 to 7.

An engine 1 schematically shown in FIG. 1 is installed in an automobile and includes an electronically controlled fuel injection device 2. The engine 1 shown schematically in FIG. The electronically controlled fuel injection device 2 includes a fuel injection valve 4 attached to an intake pipe 3 and an electronic control device 5 that controls the operation of the fuel injection valve 4.
The injection amount of fuel supplied to the engine is adjusted by the electronic control device 5 based on information from various sensors and the like.

The fuel injection valve 4 has a built-in electromagnetic coil, and when the injection signal a is applied to the electromagnetic coil from the electronic control device 5, the fuel injection valve 4 injects an amount of fuel corresponding to the fuel injection time into the vicinity of the intake port. It has become.

The electronic control unit 5 includes a central processing unit 7 and a memory 8.
, an input interface 9, an output interface 10, etc. The input interface 9 receives at least an intake pressure signal from a pressure sensor 12 provided in a surge tank 11, a signal C from an oxygen sensor 14 located upstream of a catalytic converter 13, and the like.
An injection signal a is output from the output interface 10 to the fuel injection valve 4. The pressure sensor 12' is capable of continuously detecting the intake pressure, and the intake pressure signal is converted into a digital electrical signal via an A/D converter (not shown). When the air-fuel ratio of the air-fuel mixture is on the lean side and the oxygen concentration in the exhaust gas is high, the oxygen sensor 14 generates an electromotive force that is lower than a reference value that exists near the stoichiometric air-fuel ratio, and reduces the air-fuel ratio of the air-fuel mixture. When the fuel ratio is on the rich side and the oxygen concentration in the exhaust gas is high, it is configured to generate an electromotive force higher than the reference value. Then, the electronic control device 5
If the temperature of the engine cooling water is above a predetermined value, the engine 1
When the feedback control conditions such as not being in a high load/high speed rotation state are satisfied, the oxygen sensor 14
Based on the signal C from the air-fuel mixture, feedback control is performed to maintain the air-fuel ratio of the air-fuel mixture near the stoichiometric air-fuel ratio. That is, when the electromotive force of the oxygen sensor 14 is lower than the reference value, the injection amount of fuel supplied from the fuel injection valve 4 to the combustion chamber 6 is increased, and the electromotive force of the oxygen sensor 14 is higher than the reference value. In this case, the amount of fuel injected from the fuel injection valve 4 to the combustion chamber 6 is set to be reduced.

The electronic control unit 5 also has the role of smoothing the latest actual intake pressure actually detected and the previous actual intake pressure, and using the smoothed intake pressure for determining the engine condition, etc. ing. For example, if the latest intake pressure subjected to the smoothing process exceeds the previous intake pressure and the amount of change exceeds a set value, it is determined that the engine 1 has shifted to an acceleration state. Then, when the acceleration of the engine 1 is determined, the transient air-fuel ratio correction coefficient and the like are increased to adjust the amount of fuel. In other words, the amount of fuel is accelerated and increased in response to the amount of change in intake pressure, and
Immediately after the end of acceleration, adjustments such as attenuating the fuel injection amount are made to feedback control the air-fuel ratio of the air-fuel mixture to near the stoichiometric air-fuel ratio. The transient air-fuel ratio correction coefficient is
As schematically shown in Fig. 4, the sudden acceleration/deceleration coefficient F A EWA rapidly increases or decreases depending on changes in intake pressure after transient discrimination.
A slow acceleration/deceleration coefficient FAEW that increases or decreases slowly depending on the value obtained by multiplying by a coefficient and the difference between the intake pressure after transient discrimination and the latest intake pressure.
This is a correction coefficient obtained by adding a value obtained by multiplying B by a coefficient.

On the other hand, if the latest intake pressure subjected to the smoothing process is lower than the previous intake pressure and the amount of change exceeds the set value, it is determined that the engine 1 has shifted to a deceleration state. When the deceleration of the engine 1 is determined, the transient air-fuel ratio correction coefficient and the like are attenuated to adjust the amount of fuel. In other words, the amount of fuel is reduced during deceleration in response to the amount of change in the intake pressure, and the fuel injection amount is increased immediately after deceleration is completed to feedback control the air-fuel ratio of the air-fuel mixture to near the stoichiometric air-fuel ratio. It has become.

Furthermore, as schematically shown in FIG. 2, the electronic control device 5 is configured to control the engine 1 when the engine 1 shifts to a deceleration state while the engine 1 shifts to an acceleration state and the fuel injection amount is adjusted to increase. , the remaining amount of increase F just before the transition is reflected in the fuel reduction adjustment. That is, when deceleration reduction of fuel is executed from a state where the above-mentioned increase amount F1 remains, the deceleration reduction amount is increased by an even larger value than the remaining increase amount F1, and the fuel injection amount during deceleration corresponds to the intake pressure etc. It is set so that the amount is narrowed down even more than the amount specified. On the other hand, as schematically shown in FIG. 3, when the engine 1 shifts to an accelerating state while the engine 1 shifts to a decelerating state and the fuel injection amount is adjusted to be reduced, the remaining amount of fuel injection amount immediately before the shift occurs. This is done so that F2 is reflected in the fuel increase adjustment.

That is, when an acceleration increase of fuel is executed from a state where the above-mentioned reduction amount F2 remains, the acceleration increase amount is increased by a value even larger than the remaining reduction amount F2, and the fuel injection amount during acceleration corresponds to the intake pressure etc. The amount is set to be increased further than the amount specified.

In order to execute such control, a program as schematically shown in FIG. 5 is set in the electronic control device 5. First, in step 51, whether the sudden acceleration/deceleration coefficient FAEWA, which is set to 0 when the amount of change in intake pressure is less than a set value, is 0 or not, in other words, the engine 1
Determine whether or not is in a transient state. If the sudden acceleration/deceleration coefficient FAEWA is set to 0, it is determined that the engine 1 is in a steady state, and the sudden acceleration/deceleration coefficient FA
If EWA is not set to 0, engine 1
It is determined that is in a transient state and the process proceeds to step 52. In step 52, it is determined whether the sudden acceleration/deceleration coefficient FAEWA is positive or negative, and if it is determined to be positive, it is determined that the engine 1 is in a deceleration state and the process proceeds to step 56, and if it is determined to be negative In step 53, it is determined that the engine 1 is in an accelerating state, and the process proceeds to step 53. In step 53, it is determined whether the slow acceleration/deceleration coefficient FAEWB is negative or not. If it is negative, it is determined that the acceleration is being performed, and if it is not negative, it is determined that the engine
It is determined that the vehicle has shifted to a deceleration state, and the process proceeds to step 54.

In step 54, the value of the slow acceleration/deceleration coefficient FAEWB is inverted to a negative value, and the value obtained by multiplying this value by the coefficient KA is set at the address FA.
Set it to EWBK and proceed to step 5.

On the other hand, in step 56, it is determined whether the slow acceleration/deceleration coefficient FAEWB is positive or not. If it is positive, it is determined that the engine is decelerating, and if it is not positive, it is determined that the engine 1 has transitioned to an acceleration state. After making a judgment, the process proceeds to step 57. In step 57, the value of the slow acceleration/deceleration coefficient FAEWB is inverted to a positive value, the value obtained by multiplying the coefficient by 8 is set in address FAEWBK, and the process proceeds to step 59. In step 59, address FA
The value set in EWBK is used as the transient air-fuel ratio correction coefficient FAE.
Add it to W and use that value as the value to actually use the address FA.
Set to EW. Such control is repeatedly executed during engine operation.

According to the configuration described above, when the engine 1 shifts from a steady state to an acceleration state, the amount of fuel is accelerated and increased in accordance with the amount of change in intake pressure, and the amount of fuel injection is attenuated immediately after acceleration ends. Adjustment is performed, and the air-fuel ratio of the air-fuel mixture is feedback-controlled to near the stoichiometric air-fuel ratio.

On the other hand, when the engine 1 shifts from a steady state to a deceleration state, the amount of fuel is reduced during deceleration in accordance with the amount of change in intake pressure, and adjustments such as increasing the fuel injection amount are made immediately after the end of deceleration. The air-fuel ratio of air is feedback-controlled to near the stoichiometric air-fuel ratio.

Then, when the engine 1 shifts to a deceleration state while the engine 1 shifts to an acceleration state and the fuel injection amount is adjusted to increase, the remaining increase amount F1 immediately before the shift is reflected in the fuel reduction adjustment. That is, when deceleration reduction of fuel is executed from a state where the above-mentioned increased amount F1 remains, the remaining increased amount F1
The deceleration reduction amount is increased by a value larger than 1,
The fuel injection amount during deceleration is further reduced than the amount corresponding to the intake pressure, etc. (steps 51 to 54→59).

Further, if the engine 1 shifts to an acceleration state while the engine 1 shifts to a deceleration state and the fuel injection amount is adjusted to decrease, the remaining reduction amount F2 immediately before the shift is reflected in the fuel increase adjustment. That is, when accelerated fuel increase is executed from a state where the above-mentioned reduction ability F2 remains, the remaining reduction amount F2
The acceleration increase amount is increased by an even larger value, and the fuel injection amount during acceleration is further increased than the amount corresponding to the intake pressure etc. (steps 51→52→56→57→59).

Therefore, according to the above configuration, when the engine 1 is accelerated or decelerated from a steady state, the amount of fuel injected from the fuel injection valve 4 to the combustion chamber 6 is adjusted depending on each transient state. is adjusted, it is possible to improve the control accuracy of the air-fuel ratio in a transient state, and it is possible to effectively suppress deterioration of drivability and emissions.

If the engine 1 shifts to a deceleration state and a fuel reduction adjustment is performed while the engine 1 shifts to an acceleration state and a fuel increase adjustment is performed, the remaining amount is increased at the time of the fuel increase adjustment. Since the minute F1 and the fuel situation in the intake pipe 2 are reflected in the reduction adjustment, it is possible to perform an appropriate reduction adjustment according to the deceleration situation.

Therefore, as schematically shown in FIG. 6, variations in the air-fuel ratio A/F when the engine 1 shifts from an acceleration state to a deceleration state can be effectively suppressed, and the fuel consumption level can be adjusted appropriately and sufficiently. Since it can be reduced, emissions during deceleration, drivability, etc. can be improved.

In addition, if the engine 1 shifts to an accelerating state and increases the amount of fuel while the engine 1 shifts to a deceleration state and a fuel reduction adjustment is performed, the remaining fuel at the time of the reduction adjustment is Since the minute F2 and the fuel situation in the intake pipe 2 are reflected in the increase adjustment, it is possible to perform an appropriate increase adjustment according to the acceleration situation.

Therefore, as schematically shown in FIG. 7, variations in the air-fuel ratio A/F when the engine 1 shifts from a deceleration state to an acceleration state can be effectively suppressed, and the increase in fuel can be adjusted appropriately and sufficiently. Therefore, emissions during acceleration, acceleration response, etc. can be improved.

Although one embodiment of the present invention has been described above, it goes without saying that the present invention is not limited to the above embodiment.

For example, when reflecting the remaining increase in fuel amount when increasing the amount of fuel in the reduction adjustment, or when reflecting the remaining reduction in fuel amount when adjusting the amount of fuel in the increase adjustment, the respective increase rates are adjusted according to the engine status, engine characteristics, etc. By making appropriate changes, it is also possible to perform even more precise control.

[Effects of the Invention] As detailed above, the present invention not only adjusts fuel according to the acceleration state and deceleration state, but also adjusts the engine status immediately before the transition when mutually transitioning between these states. Since this is reflected in the subsequent fuel adjustment, it is possible to reliably improve the control accuracy of the air-fuel ratio in a transient state, and it is also possible to effectively improve emissions, drivability, etc. in a transient state.

[BRIEF DESCRIPTION OF THE DRAWINGS] FIGS. 1 to 7 show an embodiment of the present invention, FIG. 1 is an explanatory diagram of the configuration, and FIGS. 2 and 3 each show a fuel control mode during a transient period. 4 are diagrams showing the air-fuel ratio correction coefficient during transient times, FIG. 5 is a flowchart diagram showing the control procedure, and FIGS. 6 and 7 are diagrams each showing changes in the air-fuel ratio during transient times. FIGS. 8 to 13 show conventional examples, FIGS. 8 to 11 show fuel control modes during transient times, and FIGS. 12 and 13 show changes in air-fuel ratio during transient times, respectively. FIG. 1...Engine 2...Electronically controlled fuel injection device 4...Fuel injection valve 5...Electronic control device 6...Combustion chamber 12...Pressure sensor F work...Remaining increase amount F2.・Remaining reduction in personnel

Claims (1)

[Claims] In a transient air-fuel ratio control method configured to increase the fuel injection amount when the engine shifts to an acceleration state and to decrease the fuel injection amount when the engine shifts to a deceleration state, If the engine shifts to a deceleration state during the adjustment to increase the fuel injection amount, the remaining increase in the fuel injection amount is reflected in the reduction adjustment to increase the deceleration reduction amount, and the engine shifts to an acceleration state during the adjustment to decrease the fuel injection amount. 1. A method for controlling an air-fuel ratio during a transient period, characterized in that, in this case, the remaining decrease in fuel injection amount is reflected in acceleration adjustment to increase the increase in acceleration.