JP2000310142A - A method for controlling the air-fuel mixture of an internal combustion engine in extreme dynamic processes - Google Patents

Abstract

PROBLEM TO BE SOLVED: To avoid the deterioration (shock, misfire) of a traveling characteristic in an extremely dynamic process by deactivating a lambda control part when a mixture enrichment exceeding a threshold or a mixture leaning under the threshold occurs in a prescribed period. SOLUTION: A lambda control part 1 outputs an output signal Fr 1 showing fuel injection control quantity during the operation of an engine. At this time when a large mixture enrichment or a large mixture leaning is present, the lambda control part 1 is deactivated by the output signal of an OR gate 2. Namely, the normal lambda control of the lambda control part is invalided, and the lambda value is set to a neutral value (e.g. 1.0). In the OR gate 2, logic 1 is applied to an input side ebag when the lambda control part 1 is to be deactivated because of large mixture enrichment, and to an input side evag when the lambda control part 1 is to be deactivated because of large mixture leaning.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for controlling an air-fuel mixture of an internal combustion engine in an extreme dynamic process, in which a lambda control is present.

[0002]

2. Description of the Related Art As described in EP 0 370 091 B1, an internal combustion engine is usually provided with a lambda control unit. Lambda is a measure of the air-fuel ratio of the mixture supplied to the cylinders of the internal combustion engine. The lambda control unit changes the supplied fuel so that the lambda value is adjusted to 1 when the actual lambda value measured by the lambda sensor deviates from the lambda target value.

[0003] In the case of extreme dynamic processes of the internal combustion engine, ie in the case of extreme acceleration and deceleration, large changes in the inner wall film (Wandfilm) occur in the intake pipe. Therefore, in the case of a high acceleration, a large enrichment of the air-fuel mixture occurs, and in the case of a high deceleration, a large leaning of the air-fuel mixture occurs. The actual lambda value in these cases deviates very much from the ideal value 1. Thus, the lambda control creates large control fluctuations in the case of extreme dynamic processes, which can lead to perceptible degradation of the running characteristics.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to reduce the running characteristics (for example, in an extreme dynamic process).
It is an object of the present invention to provide a method for controlling an air-fuel mixture of an internal combustion engine to avoid impacts and misfires.

[0005]

SUMMARY OF THE INVENTION The object of the present invention is to achieve either a large mixture enrichment above a threshold during a predetermined period or a large mixture lean below a threshold during a predetermined period. In some cases, this is solved by deactivating the lambda control.

[0006]

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a method for determining whether a large mixture enrichment above a threshold occurs during a predetermined period of time or a large mixture lean below a threshold occurs during a predetermined period of time. , The lambda control is deactivated. Due to this intervention in the lambda control, good driving characteristics are achieved in the case of extreme dynamic processes.

[0007] Advantageous embodiments of the invention result from the dependent claims.

In addition to the fulfilled conditions for large mixture enrichment, the output signal of the lambda control is below the upper threshold value or the lambda control is additionally provided in addition to the fulfilled conditions for large mixture enrichment. It is advantageous if the lambda control is deactivated if the output signal of the unit is below the lower threshold.

If the lambda control is deactivated during a large mixture enrichment or lean operation, this deactivation takes place only for a time that depends on the engine temperature.

[0010] Advantageously, the lambda control for large mixture enrichment is provided either when the load gradient is below the first threshold value or when a condition for large mixture enrichment exists. Is terminated. The deactivation of the lambda control is terminated for a large mixture leaning either if the load gradient is above the second threshold or if there is a condition for a large mixture enrichment. . Advantageously, the first and second threshold values are dependent on the engine temperature.

[0011]

BRIEF DESCRIPTION OF THE DRAWINGS FIG.

Block 1 represents a lambda controller which is known per se and will not be described in detail here. The output signal Fr1 of the lambda control unit is a control amount for fuel injection. If the internal combustion engine has two engine banks, the lambda control unit 1 supplies control amounts Fr1 and Fr2 for fuel injection to each engine bank.

[0013] Either there is a large mixture enrichment, as occurs at high vehicle accelerations, or a large mixture lean, as occurs at high vehicle decelerations, The lambda control unit 1 is inactivated by the output signal B_pspaus of the OR gate 2. The deactivation of the lambda control unit means that the normal lambda control is invalidated and the lambda value is set to a neutral value (for example, 1.0). Therefore, the lambda control no longer follows the signal of the lambda sensor. As a result, too great a leaning or enrichment of the mixture is no longer possible due to unsteady processes.

The OR gate 2 has two inputs ebag and evag. If the lambda control unit 1 is to be deactivated for large mixture enrichment, the input side eba
Logic 1 is applied to g. If the lambda control 1 is to be deactivated for large mixture leaning, a logic 1 is applied to the input evag. Under any condition, the input side ebag or evag of this OR gate 2
Can be seen from this functional block diagram. This functional block diagram consists of two similarly configured branches. OR gate 2 input side eba
g, the first branch is connected to the lambda controller 1
Are determined. Input side e of OR gate 2
In the second branch connected to the vag, a condition for deactivating the lambda control unit 1 due to a large mixture leaning is determined.

In order for a signal having a logic 1 to be applied to the input side ebag of the OR gate 2, three conditions must be satisfied. AND gate 3 detects whether these three conditions exist simultaneously. The output signal of the AND gate 3 is supplied to the input side ebag of the OR gate 2.

The first condition is a signal B_bag, which indicates that there is a large mixture enrichment above a threshold. This signal B_bag is applied to the set input side S of the flip-flop 4. As a result, the flip-flop 4 is set, and when the flip-flop 4 is set by the signal B_bag, a signal having a logic 1 is sent to the input side of the AND gate 3.

The second condition is that this signal B_bag, which indicates a large mixture enrichment, is at logic 1 for a predetermined period, that is, the large mixture enrichment lasts for a predetermined period. Whether this signal B_bag for a large mixture enrichment is at logic 1 for a predetermined period of time is detected, for example, by a counter 5. The counter 5 increases its counter state while the signal B_bag is being applied. If signal B_bag has a state logic 1 until a predetermined duration TVUKGBM has elapsed,
Logic 1 is sent to AND gate 3 via blocks 6 and 7. In block 6, an inquiry is made as to whether the counter 5 has counted back (zurueckzaehlen) to 0, ie whether the time TVUKGBM has elapsed. If counter state 0 has been reached, a trigger pulse (corresponding to logic 1) is generated for AND gate 3 in block 7.

This duration TVUKGBM depends on the engine temperature, and the duration TVUKGBM whose characteristic curve 8 belongs to the corresponding instantaneous engine temperature is sent to the counter 5.

The third condition for the AND gate 3 to send a logical 1 to the input side ebag of the OR gate 2 is that the output signal Fr1 of the lambda control unit 1 is smaller than the upper threshold value FRMBAO (for example, 1.016). is there. Threshold judgment unit 9
Is the output signal Fr1 of the lambda control unit 1 and the upper threshold value FRMB
A comparison with AO is performed. If the stereo lambda control for the two engine banks exists, the average value of the two output signals Fr1 and Fr2 of the lambda control unit 1 is compared with the above upper threshold value FRMBAO. Two output signals Fr
The average value of Fr1 and Fr2 is calculated by adding and combining unit 10 and dividing circuit 1
Calculated using 1. The division circuit 11 divides the sum signal of Fr1 and Fr2 by a coefficient 2. This third condition based on this threshold determination prevents too great a leaning of the mixture.

When one of the following three conditions is satisfied, the flip-flop 4 is reset again. As a result, the output signal of the AND gate becomes state logic 0,
According to this, the output signal B_pspause of the OR gate 2 is output.
Also have a logical zero. Thus, the deactivation of the lambda control is reversed. Of course, the reactivation of the lambda control 1 takes place after the deactivation of only a predetermined time delay TLRBAM. This time delay depends on the engine temperature,
It is set in advance by the characteristic map 12.

Signals representing the following three conditions for reactivating the lambda control unit 1 are applied to the input side of the OR gate 13. The output side of the OR gate 13 is connected to the reset input side R of the flip-flop 4. The first condition for reactivating the lambda control unit 1 is that the lambda control unit 1 has been previously deactivated. Therefore, the output signal of the AND gate 3 is fed back to the input side of the OR gate 13. Thus, after the lambda control is deactivated, the deactivation is reversed by the time delay TLRBAM. The second condition for the reactivation of the lambda control unit 1 or the prevention of the deactivation of the lambda control unit 1 lies in the signal B_vag. This signal B_v
ag has state logic 1 if there is a large mixture leaning. A third condition for reactivating the lambda control unit 1 or preventing deactivation of the lambda control unit 1 is that the load gradient dtl of the internal combustion engine is below the threshold value DTLUKVM. This threshold value DTLUKVM is represented by the characteristic curve 14
Obtained from Thus, if one of the above three conditions exists, the previously set flip-flop 4 is reset or, in particular, the flip-flop 4
Is set, and as a result, the deactivation of the lambda control unit 1 is prevented.

A logical 1 is applied to the three inputs of the AND gate 15.
Are applied simultaneously, that is, at the same time there are three conditions described below at the same time, and therefore the output signal of AND gate 15 with state logic 1 is OR
When the voltage is applied to the input side evag of the gate 2, the lambda control unit 1 is inactivated to largely reduce the mixture.

The first condition is that the signal B_vag exists. This signal B_vag has a state logic 1 during a large mixture leaning. This signal B_vag is applied to the set input side S of the flip-flop 16.
The flip-flop 16 then applies a logic 1 to the input of the AND gate 15.

The second condition for deactivating lambda control unit 1 is that signal B_vag is set to state logic 1 for a predetermined period. Whether the signal B_vag is set to state logic 1 for the entire duration TVUKGVM is detected by the counter 17. This counter 17 changes its counter state as long as the signal B_vag with its state logic 1 is applied and does not exceed the period TVUKGVM. When the counter 17 is in the period TVUKG
If the count is up until VM has passed, the logic 1 is output to the AND gate 15 via the circuit blocks 18 and 19.
Is sent to the input side. In block 18, the counter 1
Whether 7 was counted back to 0, ie
An inquiry is made as to whether the time TVUKGVM has elapsed.
If counter state 0 has been reached, a trigger pulse (corresponding to a logical 1) is generated in block 19 by AND gate 15
Generated for This time TVUKGVM is obtained from a characteristic curve 20 which depends on the engine temperature.

A third condition for deactivating the lambda control unit 1 is that the output signal Fr1 of the lambda control unit or the average value of the two output signals Fr1 and Fr2 is set to the lower threshold value FRMVAO.
(For example, 0.95). Signal Fr
The comparison of the average value of the signals 1 to Fr1 and Fr2 with the lower threshold value FRMVAO is performed in block 21 by threshold value determination. This third condition based on this threshold determination prevents too great an enrichment of the mixture.

Lambda control unit 1 for large mixture dilution
Is inactivated for a predetermined time TL depending on the engine temperature.
It must be done only during RVAM. For this purpose, a delay element 22 is connected between the output of the AND gate 15 and the input of the OR gate 2. After the deactivation of the lambda control 1, this lambda control 1 is reactivated after the above TLRVAM time delay, or if one of the following three conditions is present: Inactivation is prevented.

As a first condition, the output signal of the AND gate 15 is fed back to the first input of the OR gate 23. The output side of the OR gate 23 is connected to the reset input side of the flip-flop 16. As soon as the output signal of the AND gate 15 becomes the state logic 1, that is, as soon as the deactivation of the lambda control unit 1 is started, the output signal of the OR gate 23 becomes the state logic 1 as well. Reset. This causes the output signal of AND gate 15 to return to state logic 0 again. This logic 0 is applied to the input eva of the OR gate 2 according to the time delay TRVAM in block 22.
g. Thereby, the output signal B_pspaus of the OR gate 2 is set to logic 0, and as a result, the lambda controller 1 is activated again.

As a second condition, the second condition of the OR gate 23
Is supplied with a signal B_bag. This signal B_
If bag has state logic 1, it signals a large mixture enrichment. In such a case, OR
The output signal of gate 23 either resets flip-flop 16 or prevents flip-flop 16 from being set. As a result, the output signal of the AND gate 15 is not set to logic 1, and therefore the lambda control unit 1 is not deactivated.

The third condition that causes the flip-flop 16 to reset, thereby causing the lambda control to reactivate or prevent the lambda control 1 from activating, is:
That is, the load gradient dtl is above the threshold value DTLUKBM. Thus, if the signal dtl representing this load gradient exceeds the threshold value DTLUKBM stored in the characteristic map 24 as a function of the engine temperature, a logic 1 is applied to the third output of the OR gate 23, which results in a flip-flop. Is reset, which causes the AND gate 15
Output signal becomes state logic 0.

[Brief description of the drawings]

FIG. 1 is a functional block diagram for a method of controlling an air-fuel mixture in an extreme dynamic process.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Lambda control part 2 OR gate 3 AND gate 4 Flip-flop 5 Counter 6 Block 7 Block 8 Characteristic curve 9 Threshold value judging device 10 Addition coupling part 11 Divider circuit 12 Characteristic map 13 OR gate 14 Characteristic curve 15 AND gate 16 Flip-flop 17 Counter 18 block 19 block 20 characteristic curve 21 threshold value judging device 22 delay element 23 OR gate 24 characteristic map

The continuation of the front page (72) Inventor Thomas Edelman Germany

Claims (5)

[Claims] 1. A method for controlling an air-fuel mixture of an internal combustion engine in an extreme dynamic process, wherein a lambda control is present for controlling the air-fuel mixture of the internal combustion engine in an extreme dynamic process. In the method of (1), a large mixture enrichment exceeding a threshold value occurs during a predetermined period (TVUKGBM) or a predetermined period (TVUKGBV)
The lambda control unit (1) is deactivated in the event that either a large mixture leaning below a threshold occurs in M), the air of the internal combustion engine in an extreme dynamic process, Method for control of fuel mixture. 2. The output signal (Fr1, Fr2) of the lambda control unit (1) is additionally set to an upper threshold value (FRMBAO) in addition to the condition (B_bag) satisfying the large mixture enrichment.
Or in addition to the condition (B_vag) satisfying the large mixture leanness, the output signals (Fr1, Fr2) of the lambda control unit (1) are additionally set to the lower threshold (FR).
Method according to claim 1, characterized in that the lambda control (1) is deactivated either below or below MVAO). 3. A time dependent on engine temperature (TLRB)
Method according to claim 1, characterized in that the deactivation of the lambda control (1) takes place during (AM, TLRVAM). 4. The method according to claim 1, wherein the load gradient (dtl) is a first threshold (DT).
LUKVM) or if there is a large mixture lean condition (B_vag),
The deactivation of the lambda control unit (1) is terminated for a large mixture enrichment and the load gradient (dtl) is above a second threshold value (DTLUKBM) or the condition (B_ba) for a large mixture enrichment
2. The method as claimed in claim 1, wherein the deactivation of the lambda control (1) is terminated due to a large mixture leaning in the event that g) is present. 5. The first and second threshold values (DTLUKVM,
5. The method according to claim 4, wherein DTLUKBM is dependent on engine temperature.