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Method for urea injection control

A urea injection, urea technology, applied in the field of SCR system, can solve the problems of bad evaporation and precipitation, setting hard temperature limit is not ideal, etc.

Active Publication Date: 2011-03-30
INT ENGINE INTPROP CO LLC
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0006] However, setting hard temperature limits is not ideal
Poor evaporation and precipitation can result if the temperature limit is set too low

Method used

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  • Method for urea injection control
  • Method for urea injection control

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Experimental program
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Embodiment Construction

[0009] See figure 1 , For the maximum allowable urea solution injection rate (F urea_max ) According to the exhaust gas flow rate (F exh ) And temperature (T exh ) Limit the rate of urea administration. The restriction rule is determined empirically. The current flexible limit is contrary to the hard limit of the prior art. In the prior art, the urea injection stops when the exhaust gas temperature does not fall within the temperature limit.

[0010] In the urea injection control system 10, the controller 12 controls the urea flow rate at the urea injector 14, and the urea injector 14 injects urea into the exhaust pipe 16 of the vehicle to be decomposed upstream of the SCR catalyst 18. The controller 12 has a preferred value 20 and a variable value calculator 22. The preferred value of 20 is determined by the ammonia concentration required to optimize the performance of the SCR catalyst, and may include factors such as NOx flow rate, NOx conversion requirements, SCR power, amm...

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Abstract

A urea injection control system (10) for a vehicle having an exhaust line (16) in fluid communication with a SCR catalyst (18) and a urea injector (14) for injecting urea into the exhaust line includes a controller (12) for controlling the flow rate of urea injection at the urea injector. The controller (12) compares an optimum urea flow rate (20) with a flexible urea flow rate (22) determined by a flexible flow rate calculator. The controller (12) selects the minimum value of the optimum urea flow rate (20) and the flexible urea flow rate (22), and controls the urea injector (14) to inject urea at the minimum value.

Description

Technical field [0001] The present invention relates generally to SCR systems, and more specifically to a control method for injecting urea into the SCR system. Background technique [0002] Generally, a urea selective catalytic reduction system (urea SCR system) is used to reduce nitrogen oxides from internal combustion engines. The urea SCR system relies on injecting a 32.5% hydrophilic urea solution into the exhaust line of the vehicle upstream of the SCR catalyst. In the SCR catalyst, urea is decomposed, and N is discharged from the catalyst 2 , H 2 O and CO 2 . [0003] During spraying, the temperature of the urea solution is generally close to room temperature and preferably lower than 60°C. The SCR reaction requires gaseous ammonia. In order to produce gaseous ammonia, the sprayed urea solution must be preferably heated to 150°C to evaporate the water and decompose the remaining solid urea into ammonia and isocyanic acid. If the evaporation and decomposition are not comp...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): F01N3/20F01N3/24F01N9/00B01D53/94
CPCF01N9/00F01N2900/1812F01N2610/02F01N3/208Y02T10/24Y02T10/47Y02A50/20Y02T10/12Y02T10/40
Inventor V·司脱特斯S·C·怀亚特
Owner INT ENGINE INTPROP CO LLC