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Control method for double SCR (Selective Catalytic Reduction) system

A control method and exhaust system technology, which is applied to the electronic control of exhaust treatment devices, machines/engines, mechanical equipment, etc., and can solve the problems such as the difficulty of judging the complexity of NOx sensors

Pending Publication Date: 2022-07-12
DELPHI INT OPERATIONS LUXEMBOURG S A R L
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0009] The added complexity of the above control and its additional NOx sensor is difficult to judge, since the second doser is mainly ( / only) used for very high exhaust temperature conditions, such as DPF regeneration

Method used

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  • Control method for double SCR (Selective Catalytic Reduction) system
  • Control method for double SCR (Selective Catalytic Reduction) system
  • Control method for double SCR (Selective Catalytic Reduction) system

Examples

Experimental program
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Embodiment 1

[0084] As mentioned above, closed loop control will be imprecise when alternating from one doser to another, so it is preferable to disable a period of time (flush time) to ensure that the closed loop does not turn one doser ( / The potential drift of the SCR catalyst) is considered the drift of the currently operating doser.

[0085] In the method according to the invention, the control then introduces a feature that determines an adequate flush time and (preferably) keeps this to a minimum; this also minimizes the time the closed loop is deactivated. The washout period is based on the embedded chemical model of each SCR catalyst. During the deactivation of closed loop control during the flush period, there is preferably open loop control, although this is not required.

[0086] above image 3 Shows how the flush amount and time can be calculated. The graph is roughly divided into top and bottom. The top shows the principle of how to determine the first SCR unit flush amou...

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PUM

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Abstract

A method of controlling a vehicle exhaust system, the vehicle exhaust system comprising a first SCR unit and a second SCR unit downstream of the first SCR unit, and comprising a first urea doser adapted to inject a urea reductant upstream of the first SCR unit, and a second urea doser located upstream of the second SCR unit and adapted to inject urea upstream of the second catalytic unit, the method comprising the steps of: providing a model or MAP of the second SCR unit adapted to provide a demand signal for the second doser; the model or MAP includes one or more stored parameters indicative of characteristics of a second SCR unit and / or its doser; the method further comprises the following steps after operating the first doser: a) turning off the operation of the first doser; b) operating the second doser for a washing period; c) operating the second SCR in a closed-loop control after the expiration of the washout time, d) updating the model or MAP itself and the doser during the closed-loop control.

Description

technical field [0001] The present application relates to a method of controlling the operation of a catalytic unit in a vehicle exhaust system, such as those including a selective catalytic reduction (SCR) unit, in which ammonia stored in the SCR unit converts NOx. It is particularly suitable for exhaust systems comprising a first SCR unit located upstream of a second SCR unit, and wherein each SCR unit has a respective urea (reductant) doser unit located upstream of it. For the corresponding SCR unit, the doser doses the urea which is converted into ammonia (NH3). It is particularly suitable for a method of controlling the dosing of reducing agent (urea) in the dosing device. Background technique [0002] Especially in diesel applications in CN6b and Euro 6d / Euro7 markets, improved emission control is required, so this will require a more sophisticated vehicle exhaust aftertreatment system than CN6a or Euro6d-temp. [0003] A typical variant consists of a dual SCR cataly...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): F01N3/20F01N9/00F01N13/00
CPCF01N3/208F01N9/00F01N13/0093F01N2560/026F01N2560/14F01N2610/02F01N2610/1453F01N2900/1616F01N2900/1622F01N2900/1812F01N2900/1621F01N2900/0408F01N2900/0412Y02A50/20Y02T10/12F01N3/206F01N3/2066F01N9/005F01N9/007F01N2610/146F01N2900/1806
Inventor M·帕门迪尔T·布鲁盖斯
Owner DELPHI INT OPERATIONS LUXEMBOURG S A R L