KR100579264B1 - Fuel cut-off nox emission catalyst purge control method of vehicle - Google Patents

Abstract

The present invention relates to a catalyst purification control method for a vehicle which performs open loop control after fuel cut-off, grasps catalyst purification, and gradually performs catalyst purification through air-fuel ratio control correction while determining fuel cut-off conditions, and cut fuel. Calculating an air mass integrated value MAF_INT_PUC during the off condition; When the fuel cut-off condition PUC is finished, determining whether the fuel cell has a delay for a predetermined time (T_DLYVLS_DOWN_ACT_PUC) and a short fuel cut-off condition (Short PUC); Calculating the accumulated air amount initial value MAF_INT_DLY_PUC to maintain the catalyst purification function using the calculated air amount integrated value MAF_INT_PUC; Calculating an open loop injection correction value DELTA_LAMB_SP_PUC; After applying the open loop injection correction value (DELTA_LAMB_SP_PUC), if the value of the rear oxygen sensor is reversed from lean state to rich state according to the operation state, the catalyst purge function is terminated and normal And proceeding to Normal Closed Loop Lambda Control.

Vehicle, catalyst, purification, fuel cut off, open loop

Description

FUEL CUT-OFF NOX EMISSION CATALYST PURGE CONTROL METHOD OF VEHICLE}

1 is a flowchart illustrating a method for controlling catalyst purification of a vehicle according to an exemplary embodiment of the present invention.

2A and 2B show the results of comparative evaluation on a vehicle in order to cope with an enhanced exhaust regulation applied in North America since 2005;

The present invention relates to a method for controlling catalyst purification of a vehicle.

In general, when the vehicle is decelerated, fuel cut-off is generated to reduce fuel consumption.

During this period, the catalyst is filled with oxygen, which makes it vulnerable to nitrogen oxide (NOx) emission for a certain period of time during the operation, so the closed loop lambda is controlled to purify the oxygen present in the catalyst. During control, a method of shifting lambda control richly using a delay delay (P_Jump Delay) is used.

When using the above method, conventionally, in order to cope with the North American E / M regulation, it is difficult to contribute to catalytic purging by using only Rich Lambda Shift. NOx) reveals the limit of emissions.

SUMMARY OF THE INVENTION An object of the present invention is to provide a catalyst purification control method for a vehicle which performs open loop control after fuel cut-off and grasps catalyst purification and gradually performs catalyst purification through air-fuel ratio control correction.

In order to achieve the above object, the present invention includes the steps of determining the fuel cut-off condition, and calculating the air mass integrated value (MAF_INT_PUC) during the fuel cut-off condition; When the fuel cut-off condition PUC is finished, determining whether the fuel cell has a delay for a predetermined time (T_DLYVLS_DOWN_ACT_PUC) and a short fuel cut-off condition (Short PUC); Calculating the accumulated air amount initial value MAF_INT_DLY_PUC to maintain the catalyst purification function using the calculated air amount integrated value MAF_INT_PUC; Calculating an open loop injection correction value DELTA_LAMB_SP_PUC; After applying the open loop injection correction value (DELTA_LAMB_SP_PUC), if the value of the rear oxygen sensor is reversed from lean state to rich state according to the operation state, the catalyst purge function is terminated and normal And proceeding to Closed Loop Lambda Control.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. While many specific details, such as the following description and the annexed drawings, are shown to provide a more general understanding of the invention, these specific details are illustrated for the purpose of explanation of the invention and are not meant to limit the invention thereto. And a detailed description of known functions and configurations that may unnecessarily obscure the subject matter of the present invention will be omitted.

Embodiments of the present invention relate to catalyst purge control logic for reducing nitrogen oxide (NOx) emission after fuel cut-off, and fuel cut-off. Unlike the conventional closed loop method, the open loop control is carried out to purify the catalyst after the step. A / F) Control correction effectively performs catalyst purification.
In addition, the method of grasping catalytic purification under the open loop control checks the amount of NOx generated when the vehicle is driven by a modal graph (through an analyzer), and analyzes the NOx reduction by adjusting the air-fuel ratio through the open loop control. The appropriate air-fuel ratio is determined by checking the modal data through.
A method of controlling catalyst purification of a vehicle according to a control operation of an engine control unit ECU according to an embodiment of the present invention will be described with reference to FIG. 1.

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First, the fuel cut-off condition (hereinafter referred to as "PUC") is determined, and the air quantity integrated value MAF_INT_PUC during the fuel cut-off condition PUC is calculated (S110, S112).

After the fuel cut-off condition PUC is finished, it is determined that the fuel cell has a delay (T_DLYVLS_DOWN_ACT_PUC) for a predetermined time and is a short fuel cut-off condition (Short PUC) (S114 and S116).

The accumulated air amount initial value MAF_INT_DLY_PUC to maintain the catalyst purge function is calculated using the calculated air amount integrated value MAF_INT_PUC, which has a table value according to the air amount integrated value MAF_INT_PUC (S118). .

The accumulated air amount initial value MAF_INT_DLY_PUC is subtracted from the initial value as described later, and when 0 is reached, the catalytic purification function is terminated.

The open loop injection correction value DELTA_LAMB_SP_PUC is calculated by the actual air amount MAF_KGH and is followed by the increment and decrease values according to the change of the actual air amount MAF_KGH (S120).

After applying the open loop injection correction value (DELTA_LAMB_SP_PUC), if the value of the rear oxygen sensor is reversed from lean state to rich state depending on the operating state, the catalytic purge function is finished and normal closing The process proceeds to a normal closed loop lambda control (S122, S124).

The corrections above are each controlled if they have multiple forward catalysts.

The calculation of the accumulated air amount initial value MAF_INT_DLY_PUC and the correction value are as follows.

if LV_ACT_INT_PUC_i = 1

then

if MAF_INT_DLY_PUC_i> 0

then

{MAF_INT_DLY_PUC_in = MAF_INT_DLY_PUC_in-1- (MAF_KGH * NC_FAC_MAF_INT * DELTA_LAMB_SP_PUC * IP_FAC_CAT_EFF_PUC__CAT_DIAG)}

DELTA_LAMB_SP_PUC_i = IP_DELTA_LAMB_SP_PUC__MAF_KGH ... A)

else DELTA_LAMB_SP_PUC_i = 0 reached with B)

the ramp C_DELTA_LAMB_SP_PUC_DEC

else DELTA_LAMB_SP_PUC_i = 0 without ramp!

A) The IP value for DELTA_LAMB_SP_PUC_i is reached from 0 via ramp

C_DELTA_LAMB_SP_PUC_INC.

B) When MAF_INT_DLY_PUC_i has reached 0, DELTA_LAMB_SP_PUC_i is decreased via ramp C_DELTA_LAMB_SP_PUC_DEC.

Term description

Fuel Cut-Off Condition; LV_PUC

Integral of Mass Air Flow during Fuel Cut-Off Condition; MAF_INT_PUC

An initial value of the accumulated air amount which is given an initial value by the air amount integrated value MAF_INT_PUC for maintaining the catalyst purge function, and then decreases according to the mass amount of air; MAF_INT_DLY_PUC

Status of Catalyst Purge Function; LV_ACT_INT_PUC

Determination time for prohibiting the catalyst purge function in the case of a short fuel cut-off condition; T_DLY_VLS_DOWN_ACT_PUC

Correction value used for the Open Loop Control fuel injection time during the Catalyst Purge Function (Basic Injection value * (1 + DELTA_LAMB_SP_PUC)]; DELTA_LAMB_SP_PUC

Increment and Decrease Constant values of the correction value DELTA_LAMB_SP_PUC used for the open loop condition fuel injection time; C_DELTA_LAMB_SP_PUC_INC, C_DELTA_LAMB_SP_PUC_DEC

FIG. 2A and FIG. 2B are diagrams showing the results of the comparative evaluation of the vehicle in order to cope with the enhanced exhaust regulation applied in North America since 2005.

As described above, the embodiment of the present invention corresponds to the strengthened exhaust regulations applied after 2005 in North America, thereby bringing an effect of replacing the cost increase of catalyst reinforcement to cope with exhaust regulation, and coping with environmental regulations and reducing costs. It has a dual effect.

As described above, the method for controlling catalyst purification of a vehicle according to the present invention has an effect of reducing catalyst cost by applying emission control and controlling logic.

Claims (4)

In the catalyst purification control method of a vehicle, By performing Open Loop Control after fuel cut-off, the catalyst purification is performed by gradually adjusting the air-fuel ratio control while grasping the catalyst purification. Determining a fuel cut-off condition and calculating an air quantity integrated value MAF_INT_PUC during the fuel cut-off condition; When the fuel cut-off condition PUC is finished, determining whether the fuel cell has a delay for a predetermined time (T_DLY_VLS_DOWN_ACT_PUC) and a short fuel cut-off condition (Short PUC); Calculating the accumulated air amount initial value MAF_INT_DLY_PUC to maintain the catalyst purification function using the calculated air amount integrated value MAF_INT_PUC; Calculating an open loop injection correction value DELTA_LAMB_SP_PUC; After applying the open loop injection correction value (DELTA_LAMB_SP_PUC), if the value of the rear oxygen sensor is reversed from lean state to rich state according to the operation state, the catalyst purge function is terminated and normal A method for controlling catalytic purification of a vehicle, comprising the step of proceeding with Normal Closed Loop Lambda Control. delete The method according to claim 1, wherein the integrated air amount initial value MAF_INT_DLY_PUC is subtracted from the initial value, and when the value reaches 0, the catalyst purifying function is terminated. 2. The catalyst purification control of a vehicle according to claim 1, wherein the open loop injection correction value DELTA_LAMB_SP_PUC is calculated by the actual air amount MAF_KGH and is followed by an increase and decrease value according to the change of the actual air amount MAF_KGH. Way.

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