Reducing Agent Pump Functionality Check Procedure
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Solution Overview
Problem
The existing NOx-reduction systems for combustion engines face challenges in ensuring the proper functioning of the reducing agent pump, particularly at low temperatures where the pump may not reach nominal engine speed immediately, leading to potential false error messages and inefficiencies in the metering operation.
Innovation Solution
A procedure is implemented to check the functionality of the reducing agent pump by monitoring its engine speed during a warm-up cycle, which involves controlling the pump with a constant defined signal outside its normal operating range, and starting this cycle before the remaining defrosting time of the reducing agent solution falls below a threshold, ensuring the pump reaches a defined engine speed within a set time interval.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the pump is checked for functionality by monitoring engine speed during normal operation, then the pump functionality can be verified, but at low temperatures the pump may not reach nominal engine speed immediately causing false error messages
Solution Approach 1:
The patent applies preliminary action by implementing a warm-up cycle before normal operation begins. The pump is activated early and monitored during this warm-up phase to reach nominal engine speed under controlled conditions. This preliminary operation ensures the pump is fully functional before statutory metering operations start, preventing false error messages that would occur if functionality checking happened during normal operation at low temperatures.
2Speed
If the pump warm-up cycle is started earlier before defrosting completes, then the pump reaches operational speed in time, but the system must coordinate multiple timing constraints
Solution Approach 1:
The system determines the remaining defrosting time and starts the pump warm-up cycle in advance, before the defrosting process completes. This timing coordination ensures the pump reaches nominal engine speed exactly when needed for metering operations, resolving the contradiction between achieving operational speed and managing timing complexity.
Solution Approach 2:
The control unit continuously monitors the pump's engine speed during the warm-up cycle and compares it against the nominal engine speed value. This feedback mechanism allows the system to detect when the pump has reached operational readiness and coordinate the start of metering operations accordingly, managing the timing constraints through active monitoring and adjustment.
Data Source
AI summary
A procedure for checking the functionality of a reducing agent pump (172) of a NOx-reduction system of a combustion engine (110) is thereby characterized, in that it is checked, whether the pump (172) reaches a default engine speed value in a defined time interval within defined limits.