Exhaust Aftertreatment Doser Diagnostics Using Multistage Pump Feedback
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Solution Overview
Problem
Existing exhaust aftertreatment systems for internal combustion engines do not provide a simple method to identify whether a urea doser is operating correctly or falsely.
Innovation Solution
A multistage diagnostic process is implemented to check the operational performance of reagent dosing devices by measuring pump parameters, such as pump motor speed and pressure, to identify any deviations from nominal amounts, allowing for the detection of faulty devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple reagent dosing devices are used in series, then the system can identify faulty devices through diagnostic stages, but the device complexity increases
Solution Approach 1:
The diagnostic process is segmented into multiple stages: a first stage that measures operational performance of all reagent dosing devices collectively, and second stages that individually test each device by activating one at a time while disabling others. This segmentation enables systematic fault identification without requiring complete system disassembly or complex diagnostic hardware.
Solution Approach 2:
The controller acts as an intermediary that coordinates the diagnostic process between multiple reagent dosing devices. It activates and disables devices systematically, measures pump parameters, compares readings against stored values, and determines which specific device is faulty based on the measurement results.
2Reliability
If pump parameters are measured for diagnostic purposes, then faulty dosing devices can be identified, but the measurement precision requirements increase
Solution Approach 1:
The system implements feedback by measuring pump parameters (such as pump motor speed and/or pump pressure) during operation, comparing these measurements against stored reference values in memory, and using the comparison results to determine whether a reagent dosing device is faulty. This feedback mechanism enables continuous monitoring and reliable fault detection without requiring extremely high measurement precision.
Solution Approach 2:
Reference values for pump parameters are pre-stored in the controller's memory under normal operating conditions. These preliminary established values serve as benchmarks for later comparison during diagnostic operations, enabling quick and reliable fault detection without requiring complex real-time analysis algorithms.
Data Source
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AI summary
An exhaust aftertreatment system comprises a pump; reagent dosing devices arranged in series with each other; and a controller. The controller comprises a dosing device diagnostic circuit configured to in a first stage measuring a first stage diagnostic indicating an amount of reagent dosed by all the reagent dosing devices, and comparing the measured first stage diagnostic with a nominal first stage diagnostic. If a deviation exceeds nominal performance then in a second stage of evaluation is triggered to identify a faulty reagent dosing device, wherein all the further reagent dosing devices are set to dose at a low quantity while simultaneously activating the first reagent dosing device to dose at two operating points, i.e. at a low dosing quantity and at medium or high dosing quantity and measuring a second stage diagnostic. The measured second stage diagnostic is compared with a nominal second stage diagnostic for determining if the first dosing device is operating correctly or faulty. In a third stage the first reagent dosing device is set to dose at a low quantity while simultaneously only one of the further reagent dosing devices is activated to dose at two operating points, i.e. at a low dosing quantity and at medium or high dosing quantity and a third stage diagnostic is measured and compared with a nominal second stage diagnostic for determining if said only one of said further reagent dosing devices is operating correctly or faulty.