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Method for correcting offset of ammonia-sensor

A sensor and offset technology, applied in the field of correcting the offset of ammonia-sensor, can solve problems such as ammonia-slip that cannot be ruled out

Active Publication Date: 2021-11-30
ROBERT BOSCH GMBH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

As already mentioned, ammonia sensors are usually used in SCR systems with permanently regulated, weaker overmetering, where ammonia slippage can hardly be ruled out

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  • Method for correcting offset of ammonia-sensor

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Embodiment Construction

[0028] Figure 1a The graph shows the relationship between the ammonia fill level FNH3 and the temperature T for a conventional SCR catalytic converter. In the diagram, a minimum ammonia filling level FNH3min, a nominal ammonia filling level FNH3nom and a maximum ammonia filling level FNH3max are each shown as a function of temperature T. If the ammonia filling level FNH3 is below the minimum ammonia filling level FNH3min, the nitrogen oxides flowing through the SCR catalytic converter are not completely converted by means of the SCR. However, if the ammonia-fill level FNH3 exceeds the maximum ammonia-fill level FNH3max, ammonia-slip is caused, which occurs at Figure 1b was clarified again. Therefore, when adjusting the SCR system, the ammonia filling level FNH3 should be kept between the maximum ammonia filling level FNH3max and the minimum ammonia filling level FNH3min. Highlight the marked temperature T 1 , the temperature is used at Figure 1b in the embodiment.

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Abstract

The invention relates to a method for correcting an offset of an ammonia sensor which is arranged downstream of at least one SCR catalytic converter in an SCR system. The method comprises the steps of: first, identifying ammonia-slip by means of an ammonia-sensor; then, setting the modeled ammonia-fill level (FNH3mod) to a maximum ammonia-fill level (FNH3max); and then, setting The SCR‑system performs low dosing of reductant. Low dosing ends when the modeled ammonia-fill level (FNH3mod) returns to the nominal ammonia-fill level (FNH3max). Subsequently, the current offset is determined and the offset is corrected by means of the difference between the current offset and the expected offset.

Description

technical field [0001] The invention relates to a method for correcting an offset of an ammonia sensor in an SCR system. Furthermore, the present invention relates to a computer program for carrying out each step of the method, and a machine-readable storage medium, which, when running on a computing device, stores the program. Finally, the invention relates to an electronic control device, which is designed to carry out the method according to the invention. Background technique [0002] Today, in order to reduce nitrogen oxides (NOx) in the exhaust gases of motor vehicles, SCR-catalysts ( S elective C analytic R education). Here, in the presence of ammonia (NH 3 ), the nitrogen oxide molecules that are located on the surface of the SCR catalyst are reduced to elemental nitrogen. The reducing agent is urea-water-solution (also commercially available as AdBlue ® Known form) is provided and the ammonia is separated from the urea-water-solution by injection into the ex...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): F01N3/20F01N9/00F01N11/00
CPCF01N3/208F01N9/005F01N11/00F01N2610/02F01N2900/16F01N2900/1602F01N3/2066F01N2560/021F01N2900/0408F01N2900/0416F01N2900/0418F01N2900/0601F01N2900/1616F01N2900/1622Y02T10/40F01N9/00
Inventor C.海曼F.施魏策尔
Owner ROBERT BOSCH GMBH