KR100427327B1 - Method of checking start of air and fuel ratio feedback control - Google Patents

Abstract

An air-fuel ratio feedback control start determination method is disclosed. The disclosed air-fuel ratio feedback control start determination method includes: (a) checking an oxygen sensor and a TPS output voltage; (b) determining whether the output voltage of the oxygen sensor has crossed 0.45V after 15 seconds; (c) determining the activity of the oxygen sensor when the oxygen sensor cuts 0.45V in the step (b); (d) determining whether the output voltage of the oxygen sensor is 0.45V or more; (e) if the output voltage of the oxygen sensor in step (d) is 0.45V or more, determining the fuel amount rich; (f) reducing the fuel amount with fuel amount feedback control; (g) determining whether the engine is off and terminating the flow when the engine is off. According to the present invention, there is an advantage that the stability is improved and the emission and fuel economy are not deteriorated.

Description

Air fuel ratio feedback control start judgment method {METHOD OF CHECKING START OF AIR AND FUEL RATIO FEEDBACK CONTROL}

The present invention relates to an air and fuel ratio feedback control start determination method, and more particularly, improved air-fuel ratio feedback control to improve idle stability and not to deteriorate emission and fuel economy. It relates to a start determination method.

In the fuel amount (A / F) feedback, an oxygen sensor (O2 sensor) mounted in an exhaust manifold detects the amount of oxygen in the exhaust gas, and performs fuel amount lean and rich determination.

In order to enter this feedback mode, activation of the oxygen sensor that is critical for determining the richness / leanness must be performed. The activation of the oxygen sensor is a state in which the amount of oxygen can be accurately detected, that is, the oxygen sensor is sufficiently heated. Usually activation is carried out above 350 ° C.

On the other hand, since the temperature of the oxygen sensor can not be measured in logic, the activation determination condition in the current logic is as follows.

After the engine starts, after 15 seconds (after the start of the oxygen sensor activation determination prohibition time) has elapsed, when the oxygen sensor transverses 0.45V, the determination is made to start the fuel amount feedback control.

In addition, the feedback start condition in logic is limited as follows.

Oxygen sensor activity, water temperature above the predetermined value, filling efficiency above the predetermined value, TPS (Throttle Position Sensor) opening degree below the predetermined value, after a certain time after the start (2-D Map by cooling water temperature), θ-Ne (AFS; Air Flow In addition to 2D map (by RPM control by TPS) mode when sensor failure is judged, in case of ignition system normal, OBD-II monitoring prevents forced feedback.

By the way, the conventional technique as described above cannot control the fuel amount feedback during idle after hot restart, and thus the fuel amount feedback is prohibited until the accelerator pedal is operated.

Normal soaking in cold (cooling water temperature 20 ~ 30 ℃, outdoor temperature 20 ~ 30 ℃), oxygen sensor is not activated at start-up, 0.45V or less After fixing to, it starts to be heated by the exhaust gas and oxygen sensor heater, detects the oxygen sensor and cuts 0.45V to determine the activity in the ECU to start fuel level feedback.

After soaking for a short time (before the oxygen sensor is fully cooled), the oxygen sensor is activated at start-up, so that the fuel cell is richly determined (oxygen sensor output 0.45V or more) by the initial starting fuel amount.

In addition, the start fuel amount is controlled by the logic to control the weight loss after the start stabilization. Since the engine is sufficiently cooled, a point in which the actual fuel amount is lean occurs. If, after starting, the output of the oxygen sensor which has detected the rich amount of oxygen within a predetermined time (oxygen sensor activity determination prohibition time) is previously deprived of 0.45V as described above, it is no longer possible to enter the fuel amount feedback.

FIG. 1 shows an actual measurement graph in which fuel amount feedback is not performed after hot restart, and FIG. 2 shows a graph in which fuel amount feedback mode cannot be entered after hot restart in the same vehicle and under the same conditions.

In addition, as described above, when feedback is not restarted, it may appear as an increase in exhaust gas (emission). In the exhaust gas test mode, since the mode of idle driving after hot restart is included for each region, the feedback control is not possible during the idle control, and the increase of the exhaust gas is inevitable since the basic fuel injection is performed without the fuel amount control.

The present invention has been made to solve the above problems, and an object thereof is to provide an air-fuel ratio feedback control start determination method in which idle stability is improved and emission and fuel economy are not deteriorated.

1 and 2 are actual measurement graphs that do not provide fuel amount feedback after hot restart.

3 is a schematic flowchart sequentially showing a method for determining an air-fuel ratio feedback control start according to the present invention;

The air-fuel ratio feedback control start determination method of the present invention for achieving the above object comprises the steps of: (a) checking the oxygen sensor and the TPS output voltage; (b) determining whether the output voltage of the oxygen sensor has crossed 0.45V after 15 seconds; (c) determining the activity of the oxygen sensor when the oxygen sensor cuts 0.45V in the step (b); (d) determining whether the output voltage of the oxygen sensor is 0.45V or more; (e) if the output voltage of the oxygen sensor in step (d) is 0.45V or more, determining the fuel amount rich; (f) reducing the fuel amount with fuel amount feedback control; (g) determining whether the engine is off and terminating the flow when the engine is off.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

3 is a schematic flowchart sequentially showing a method for determining an air-fuel ratio feedback control start according to the present invention.

Referring to the drawing, the air-fuel ratio feedback control start determination method according to the present invention first checks the oxygen sensor and the TPS output voltage.

Subsequently, after 15 seconds, it is determined whether the output voltage of the oxygen sensor has transversed 0.45V (step 130).

In step 130, when the oxygen sensor cuts 0.45V, the activity of the oxygen sensor is determined.

Then, it is determined whether the output voltage of the oxygen sensor is 0.45V or more (step 150).

When the output voltage of the oxygen sensor is 0.45V or more in step 150, the fuel amount rich is determined (step 160).

The fuel amount is reduced by fuel level feedback control (step 170).

It is determined whether the engine is off, and if the engine is off, the flow ends (step 180).

When the oxygen sensor does not transverse 0.45V in step 130, it is determined whether the ΔTPS (change rate of throttle valve opening) is 0.8V or more detected one or more times (step 210). In step 210, ΔTPS is 0.8V or more. If the state is not detected more than once, step 140 is performed.

When the ΔTPS is detected at least once in a state of 0.8 V or more, the fuel amount by the open loop is controlled by the basic fuel amount mapped previously (step 220). The basic fuel amount is matched to reach the lambda (lambda) = 1 (there are some deviations between vehicles) in addition to the feedback using the correction factors (RPM, EV) to the fuel amount appropriately matched to the air flow sensor (AFS) intake air amount ( Matching basic fuel amount. Children are areas of low load and fuel requirements, difficult to map perfectly, and are actually 5-10% different from the theoretical air-fuel ratio.

When the output voltage of the oxygen sensor is not 0.45V or more in step 150, a fuel amount lean is determined. (Step 310).

Next, the fuel amount is increased by the fuel amount feedback control. (Step 320).

It is determined whether the engine is off, and the flow ends when the engine is off (step 330).

In addition, in step 170 or 320, the fuel feedback feedback starting condition is 1) oxygen sensor activation, 2) oxygen inactivity determination (0.45V non-transverse) after the prohibition time (15 seconds), 3) water temperature or more, 4) Filling efficiency is more than predetermined value, 5) TPS opening degree is less than predetermined value, 6) After a certain time (2-D map according to cooling water temperature) after starting, 7) θ-Ne (Air flow sensor (AFS; Air) In addition to 2D map (by RPM) control mode when failure is detected), 8) When ignition system is normal, 9) Other than forced feedback suppression by OBD-ll monitoring.

When the fuel quantity feedback starting conditions are satisfied, the fuel quantity feedback control equation to be performed is made up of the following equation.

[Equation]

here,

{T} _ {B} = basic fuel level,

{K} _ {LRN} = air and fuel ratio learning,

{K} _ {FB} = 1 ± {K} _ {P} + {K} _ {I} (fuel feedback correction factor),

In the above, {K} _ {P} = proportional coefficient, {K} _ {I} = integral coefficient

{K} _ {MTCH} = Air Ratio Matching Correction Factor,

{K} _ {AFND} = Air-fuel Ratio Correction Factor for N-R-D Change at Low Water Temperature,

Air-fuel ratio lean correction coefficient at the initial inlet of purge air,

{K} _ {AS} = After starting, weight correction factor,

= Acceleration and deceleration fuel quantity correction factor.

If the engine is not turned off in step 180, the process is performed again from step 110.

As described above, in the air-fuel ratio feedback control start determination method according to the present invention, the oxygen sensor mounted in the exhaust manifold detects the amount of oxygen in the exhaust gas to perform fuel amount lean and rich determination.

In order to enter this feedback mode, activation of the oxygen sensor that is critical for determining richness and leanness must be made. Activation refers to a state in which the amount of oxygen can be accurately detected, that is, the oxygen sensor is sufficiently heated. Usually activation is above 350C.

In addition, since the temperature of the oxygen sensor cannot be measured by the conventional method, the activation determination condition in the present invention is as follows.

15 seconds after the engine is started (XO2CRK; prohibition time for oxygen sensor activation after starting), when the oxygen sensor transverses 0.45V, it is judged to be active, and the fuel quantity feedback (A / F feedback) control is started.

In order to solve the feedback entry problem that has been raised in the prior art, if the activation determination condition (XO2CRK: prohibition time for oxygen sensor activation after starting) is adjusted within 15 seconds, there is no problem in feedback entry, but another important problem occurs. .

If you adjust it to 10 seconds, the problem occurs as follows.

During start-up, the required fuel amount must be rich up to several times the idle state, and the rich fuel amount immediately after the start-up is tailed by a weight loss control to reduce the fuel amount. 10 seconds after start-up, the amount of fuel used at start-up is being reduced.

At this time, when the oxygen sensor determines the activity, determines the richness, and reduces the fuel amount by feedback control, a problem occurs when the independent starting fuel amount reduction is completed.

Since the feedback loss learning value immediately before the actual idle fuel amount is applied to control the fuel amount, the fuel cell may be in a lean state and increase in NOx EM or severely start up. Also, when losing by the tailing logic immediately after startup, feedback control accelerates the loss and adversely affects startup. Therefore, the oxygen sensor activation determination condition is left as it is, it is possible to improve the problem in response to the change in the start condition as described above.

In particular, in the case of inertial determination (0.45V non-transverse) even after the oxygen sensor activity determination prohibition time (XO2CRK; 15 seconds), it is classified as follows.

First, feedback is started when ΔTPS (throttle valve opening degree change rate) is maintained for a predetermined value (XTPSFB; 0.8V) for less than one time (XTIME1), that is, never after 15 seconds of starting (XO2CRK).

Second, if ΔTPS is maintained at a predetermined value (XTHSD; 0.8V) or more (XTIME1) or more after 15 seconds of startup (XO2CRK), the feedback system does not start the feedback and enters the feedback system monitoring mode.

Understanding the above requires an accurate understanding of the problems of the prior art (no fuel level feedback entry at hot restart). In other words, hot restart generally refers to a time when a driver parks the vehicle for a while after driving, and then restarts the vehicle. In the start mode, a large amount of rich fuel is consumed. Becomes

In other words, since the oxygen sensor is activated to some extent during hot restarting, the output value of the combustion furnace is maintained at 0.45 V or more during the starting. Thereafter, the start mode fuel amount control is terminated within the oxygen sensor activity determination time (15 seconds) when the oxygen sensor output value held at 0.45 V or more immediately after the start mode is completed. At this time, after the oxygen sensor falls below 0.45V, it is maintained in a state in which feedback initiation (active determination) is impossible. That is, after the activity determination prohibition time (15 seconds), 0.45V cannot be transversely determined to be inactive, and no further feedback is possible.

The reason for changing the condition using the ΔTPS condition at all times is as follows.

As described above, when the oxygen sensor is determined to be lean after 15 seconds, if the throttle opening degree is changed (or the driver presses the accelerator pedal), the air-fuel ratio is rich with the change in the fuel amount control due to the change in the engine operating area. Will be reversed.

Therefore, the first of the above conditions compensates for the logical weakness that prohibits unconditional feedback for reasons that cannot be determined. The second is to reconfirm the inertial determination of the oxygen sensor.

As described above, the air-fuel ratio feedback control start determination method according to the present invention has the following effects.

Since the problem of the active misjudgement of the oxygen sensor in the prior art is solved, the fuel amount control problem is compensated for, and when the actual feedback is not provided, the idle fuel amount control is injected by the base map, thereby suppressing the problem of deterioration in stability. Therefore, the problem of not being able to enter fuel amount feedback upon hot restart is solved, and the idle stability is improved.

And idle fuel amount control (fuel amount feedback control) can directly affect the emission (EM) and fuel economy, it is possible to prevent the emission and fuel economy deterioration.

Although the present invention has been described with reference to one embodiment shown in the drawings, this is merely exemplary, and it will be understood by those skilled in the art that various modifications and equivalent embodiments are possible. Therefore, the true scope of protection of the present invention should be defined only by the appended claims.

Claims (7)

(a) checking the oxygen sensor and the TPS output voltage; (b) determining whether the output voltage of the oxygen sensor has crossed 0.45V after 15 seconds; (c) determining the activity of the oxygen sensor when the oxygen sensor cuts 0.45V in the step (b); (d) determining whether the output voltage of the oxygen sensor is 0.45V or more; (e) if the output voltage of the oxygen sensor in step (d) is 0.45V or more, determining the fuel amount rich; (f) reducing the fuel amount with fuel amount feedback control; (g) judging whether the engine is off and ending the flow when the engine is off. The method of claim 1, (h) if the oxygen sensor does not transverse 0.45V in step (b), determining whether the ΔTPS (throttle valve opening change rate) is 0.8V or more once or more; and (i) controlling the fuel amount by the open loop when the ΔTPS is detected at least once with a state of 0.8V or more. The method of claim 2, In the step (h), if the ΔTPS is not detected more than one time of 0.8V or more, the air-fuel ratio feedback control start determination method, characterized in that the step (c) is performed. The method of claim 1, (j) if the output voltage of the oxygen sensor in step (d) is not 0.45V or more, determining a fuel amount leanness; (k) increasing the fuel amount with fuel amount feedback control; (l) determining whether the engine is off, and ending the flow when the engine is off; the air-fuel ratio feedback control start determination method according to claim 1, further comprising: The method according to claim 1 or 4, In the step (f) or (k), the fuel amount feedback start condition is equal to or greater than a predetermined temperature value when the inertial determination (0.45V non-transverse) is performed even after the oxygen sensor activity and the oxygen sensor activity determination prohibition time (15 seconds). Overcharge, filling efficiency is more than the predetermined value, less than the TPS opening degree, less than a certain time after starting (2-D Map for each cooling water temperature), and other than θ-Ne mode, when the ignition system is normal, and OBD-ll monitoring And an air-fuel ratio feedback control start determination method, which includes other than forced feedback. The method of claim 5, And when the fuel amount feedback starting conditions are satisfied, the fuel amount feedback control equation to be performed comprises the following equation. [Equation] here, {T} _ {B} = basic fuel level, {K} _ {LRN} = air and fuel ratio learning, {K} _ {FB} = 1 ± {K} _ {P} + {K} _ {I} (fuel feedback correction factor), In the above, {K} _ {P} = proportional coefficient, {K} _ {I} = integral coefficient {K} _ {MTCH} = Air Ratio Matching Correction Factor, {K} _ {AFND} = Air-fuel Ratio Correction Factor for N-R-D Change at Low Water Temperature, Air-fuel ratio lean correction coefficient at the initial inlet of purge air, {K} _ {AS} = After starting, weight correction factor, = Acceleration and deceleration fuel quantity correction factor. The method of claim 1, If the engine is not turned off in the step (g), the air-fuel ratio feedback control start determination method characterized in that to perform again from the step (a).