KR100962849B1 - Method for setting EGR - Google Patents

Abstract

The present invention relates to a method for setting an EGR amount, comprising: a first step of determining whether a condition condition for setting an EGR amount is satisfied according to an amount of change in axel pedal and a vehicle speed; The second step of determining whether the relief phenomenon occurs by using the engine speed change amount and the fuel amount change amount, and if the relief phenomenon occurs, the current EGR valve duty output value until the relief is stopped, the specific reduction ratio And a fourth step of reducing the step by step, and a fourth step of outputting the final reduced EGR valve duty output value as an EGR valve duty output value in the case where the relief phenomenon stops due to a decrease in the EGR valve duty output value.

Vehicle, EGR, unburned, NOx, engine, gas, exhaust

Description

How to set EBR amount {Method for setting EGR}

The present invention relates to a method for setting an EGR amount.

In general, engines applied to diesel vehicles are burned in a state where the excess air ratio is large due to the characteristics of diesel engines. It has a disadvantage that HC emissions are low and emissions of nitrogen oxides (NOx) and particulate matter (PM) are quite large.

In order to reduce the NOx emissions, the amount of exhaust gas recirculation (EGR) is increased. NOx components can be reduced among the exhaust gases, but vehicle embrittlement caused by excessive EGR, that is, vehicle shaking due to unburning, increases unburned gas components such as CO and HC, and lowers operability. Problems arise in terms of.

In addition, even when the EGR amount is optimally set, there are vehicles in which relief occurs intermittently due to variations in parts for each car. Therefore, the issue of how to implement the optimal EGR amount and how to overcome the vehicle deviation is becoming important.

The current method is to set the EGR amount for each operation area (based on engine speed and fuel amount). The section that generates a large amount by measuring NOx emission uses trial and error method to increase the amount of EGR and to optimize the amount of EGR while reducing the amount of EGR.

However, in such a method of setting the amount of EGR for each driving region, even when a vehicle of the same model shows a large deviation due to engine deviation. In addition, the occurrence frequency of the relief phenomenon also has a problem that a deviation occurs.

The present invention is a method for resetting the EGR amount by the engine deviation for each vehicle model.

The present invention provides a first step of determining whether the condition condition for setting the EGR amount is satisfied according to the amount of change in the accelerator pedal and the vehicle speed, and, when the condition condition for setting the EGR amount is satisfied, the engine speed change amount and the fuel amount change amount. A second step of judging whether the relief occurs using the second step; and if the relief occurs, a third step of gradually reducing the current EGR valve duty output value to a specific reduction rate until the relief stops. And a fourth step of outputting the final reduced EGR valve duty output value as an EGR valve duty output value in the future when the relief phenomenon stops due to a decrease in the EGR valve duty output value.

In the first step, when the amount of change in the accelerator pedal is less than the first threshold and the vehicle speed change is less than the second threshold, it is determined that the condition condition for setting the EGR amount is satisfied, and the first threshold is 2% / sec. The second threshold is 4kph / sec.

In the second step, it is determined that the relief occurs when the engine speed change amount exceeds the third threshold value and the fuel amount change amount exceeds the fourth threshold value, and the third threshold value is ± 30 rpm / sec. The fourth threshold value is characterized in that ± 5mg / sec.

In the third step, when the relief phenomenon occurs, step 3-1 of reducing the current EGR valve duty output value to a specific reduction ratio and determining whether the relief phenomenon is stopped using the engine speed change amount and the fuel amount change amount. Step 3-2, and repeating the steps 3-1 and 3-2 until the relief is stopped.

The specific reduction ratio is characterized in that -0.5%.

The final reduced EGR valve duty output value calculated in the fourth step is stored in the nonvolatile memory.

According to the present invention, it is possible to reduce the development and cost of expensive components for reducing the exhaust gas by optimizing the relief caused by the vehicle deviation and the optimum EGR valve duty output value through learning. In addition, the exhaust gas test results to which the logic of the present invention is applied, the vehicle deviation can be reduced by 10% compared to the existing, which has the effect of reducing the cost of the low-cost exhaust gas reduction related devices more than 10%. In addition, it may have the effect of improving the driving properties and vehicle marketability.

Hereinafter, the detailed description of the preferred embodiments of the present invention will be described with reference to the accompanying drawings. In the following description of the reference numerals to the components of the drawings it should be noted that the same reference numerals as possible even if displayed on different drawings.

1 is a flowchart illustrating a process of setting an EGR amount according to an embodiment of the present invention.

According to the present invention, when the relief phenomenon occurs due to the initial EGR amount, the relief amount may be improved by resetting the EGR amount, and the relief may be improved by continuing to apply the reset EGR amount later.

First of all, a condition for resetting the EGR amount is satisfied to determine whether the reset logic should be driven. If the amount of variation in the accelerator pedal is small and the relief occurs when the vehicle is running at constant speed, the engine speed is accompanied and the increase and decrease of the fuel amount is increased accordingly. Therefore, this empirical phenomenon is used to determine whether there is a possibility of relief phenomenon and whether the conditions for resetting the EGR amount are satisfied.

To this end, the accelerator pedal change amount and the vehicle speed change amount (acceleration) are calculated (S11) to determine whether the current driving condition having the above values is a condition for resetting the EGR amount (S12). That is, it is determined that the condition for resetting the EGR amount is satisfied when the amount of the accelerator pedal change is less than the first threshold and the vehicle speed change (acceleration) is less than the second threshold. For example, if the axel pedal change amount is less than 2% / sec and the vehicle speed change amount (acceleration) is less than 4 kph / sec, it is determined that the logic of the next step for resetting the EGR amount is to be the current driving condition.

When the condition for resetting the EGR amount is satisfied, the engine speed change amount and the fuel amount change amount are calculated (S13), and it is determined whether the present relief phenomenon has occurred with reference to the above values (S14). That is, when the engine speed change amount exceeds the third threshold value and the fuel amount change amount exceeds the fourth threshold value, it is determined that a relief phenomenon occurs. For example, it is determined that a relief phenomenon occurs when the engine speed change exceeds ± 30 rpm / sec and the fuel amount change exceeds ± 5 mg / sec.

When it is determined that the relief phenomenon occurs as described above, the specific reduction ratio (for example, -0.5%) is reduced (S15, S16, S17, S18) from the initial EGR valve duty output value.

In detail, when it is determined that the occurrence of the relief phenomenon, after reducing the -0.5% from the current EGR valve duty output value (S15), the engine speed change amount and the fuel amount change amount is calculated again (S16) and then the engine speed change amount and It is determined whether the amount of fuel change is less than or equal to the third threshold value and the fourth threshold value, respectively, in step S17. For example, it is determined that the relief phenomenon has stopped when the engine speed change amount is ± 30 rpm / sec or less and the fuel amount change amount is ± 5 mg / sec or less.

As a result of the determination, if the relief phenomenon continues even though the EGR valve duty output value is reduced to a reduction ratio of -0.5%, the cumulative number of decreases (N) is increased by 1 (S18) and the current EGR valve duty output value is decreased. Decrease again (S15) as a reduction rate of -0.5%, and proceed to steps S16 and S17 again.

As a result, the steps S15, S16, S17, and S18 are repeatedly performed until the relief stops, thereby gradually reducing the EGR valve duty output value by the reduction ratio.

When the relief phenomenon stops due to the stepwise reduction of the EGR valve duty output value, the reduced final EGR valve duty output value is calculated as the final EGR valve duty output value (S19). That is, the final EGR valve duty output value is a value to which the accumulated reduction ratio is applied from the initial EGR valve duty output value, and the accumulated reduction ratio has a value of -0.5% * N.

The calculated final EGR valve duty output value is stored in a ROM of the engine control unit ECU so that the final EGR valve duty output value is output (S20). Since the final EGR valve duty output value is stored in a nonvolatile memory such as a ROM or a flash memory, the final EGR valve duty output value is not erased even after the start-off, and thus can be used continuously in the future.

In the above description of the present invention, specific embodiments have been described, but various modifications may be made without departing from the scope of the present invention. Therefore, the scope of the present invention is not to be determined by the embodiments described above, but will be apparent in the claims as well as equivalent scope.

1 is a flowchart illustrating a process of setting an EGR amount according to an embodiment of the present invention.

Claims (8)

A first step of determining whether the condition condition for setting the EGR amount is satisfied according to the amount of the accelerator pedal change and the vehicle speed; A second step of determining whether a relief phenomenon occurs by using an engine speed change amount and a fuel amount change amount when the condition condition for setting the EGR amount is satisfied; A third step of, if the relief phenomenon occurs, gradually reducing the current EGR valve duty output value by a specific reduction ratio until the relief phenomenon stops; When the relief phenomenon stops due to the decrease of the EGR valve duty output value, the fourth step of outputting the finally reduced EGR valve duty output value as an EGR valve duty output value in the future Including, In the first step, when the amount of change in the accelerator pedal is less than the first threshold value and the vehicle speed change amount is less than the second threshold value, it is determined that the condition condition for setting the EGR amount is satisfied, and the first threshold value is 2% / sec. , The second threshold is 4 kph / sec, The first step and the second step EGR amount setting method characterized in that the amount of change in the accelerator pedal is small, and if the relief occurs when the vehicle is running at a constant speed, the engine speed is insufficient and the amount of change in fuel amount is increased. delete delete The EGR amount setting method according to claim 1, wherein the second step determines that the relief phenomenon occurs when the engine speed change amount exceeds a third threshold value and the fuel amount change amount exceeds a fourth threshold value. The method of claim 4, wherein the third threshold value is ± 30 rpm / sec, and the fourth threshold value is ± 5 mg / sec. The method of claim 1, wherein the third step, A third step of reducing the current EGR valve duty output value by a specific reduction ratio when the relief phenomenon occurs; Step 3-2 of determining whether the relief phenomenon is stopped by using the engine speed change amount and the fuel amount change amount; Repeating steps 3-1 and 3-2 until the relief stops EGR amount setting method comprising a. The method of claim 1 or 6, wherein the specific reduction ratio is -0.5%. The method of claim 1, wherein the final reduced EGR valve duty output value calculated in the fourth step is stored in a nonvolatile memory.

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