Reducing Agent Injector Temperature Monitoring
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Solution Overview
Problem
Existing selective catalytic reduction systems in vehicles undergo unnecessary purges when the engine stops, leading to energy consumption, noise, and potential damage from freezing reducing agents, due to limitations in current temperature monitoring and calibration methods.
Innovation Solution
A method that uses a controller to periodically wake up and measure the electrical resistance of the reducing agent injector, estimating its temperature and initiating a purge only when below the freezing threshold, allowing for calibratable intervals and consideration of additional parameters like outside temperature and thermal inertia to prevent freezing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the controller is systematically purged each time the vehicle stops to prevent freezing, then the risk of freezing is reduced, but energy consumption increases and noise is generated
Solution Approach 1:
The patent changes the control parameter from systematic purging to temperature-based conditional purging. The controller monitors the temperature of the reducing agent and only initiates purging when the temperature approaches the freezing point, thereby eliminating unnecessary energy consumption while maintaining freezing prevention reliability.
Solution Approach 2:
The system uses the temperature sensor and controller to automatically monitor and determine when purging is necessary, eliminating the need for manual intervention or systematic purging. The system serves itself by making intelligent decisions based on real-time temperature data.
2Measurement precision
If the controller is woken up at frequent intervals to monitor temperature, then freezing detection precision is improved, but energy consumption increases
Solution Approach 1:
The patent implements dynamic wake-up intervals instead of fixed intervals. The controller adjusts the wake-up frequency based on ambient temperature conditions - more frequent monitoring when temperatures are closer to freezing point, and less frequent monitoring when temperatures are well above freezing, thereby optimizing both detection precision and energy consumption.
Solution Approach 2:
The system performs preliminary monitoring during operation and uses predictive logic to determine when wake-up monitoring should occur. By analyzing temperature trends and ambient conditions beforehand, the controller can schedule wake-up intervals efficiently without compromising detection precision.
3Loss of energy
If a bimetallic strip switch is used to wake up the controller, then the system can operate without current draw during normal state, but the threshold cannot be modified and unwanted triggering may occur
Solution Approach 1:
The patent replaces the mechanical bimetallic strip system with an electronic temperature sensor and microcontroller-based monitoring system. This substitution eliminates the fixed threshold limitation of mechanical systems and allows for software-based, adjustable thresholds that can be calibrated according to specific operating conditions and reducing agent properties.
Solution Approach 2:
The electronic system provides dynamic and adjustable wake-up thresholds that can be modified through software calibration. Unlike the fixed mechanical bimetallic strip, the electronic threshold can be adapted to different reducing agents, ambient conditions, and system requirements, providing versatility while maintaining zero current draw in the dormant state.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach reduces unnecessary purges, conserves energy, minimizes noise, and effectively protects the system by accurately monitoring and anticipating potential freezing, thereby extending the intervals between controller awakenings and reducing the risk of damage.
Implementation Method 1
a temperature of the reducing agent at the injector is estimated as a function of the measured resistance
Data Source
AI summary
Disclosed is a method for preventing a risk of freezing in a device for supplying reducing agent to a selective catalytic reduction system in an exhaust line, a freezing temperature specific to the agent being stored in memory, the system including a controller operating the system and emitting pulses to an injector, the controller being inactive when the engine is switched off. With the combustion engine switched off, the controller is woken up at predetermined intervals to initiate an emission of a specific electric pulse to the injector with measurements of a current-strength and voltage of the electric pulse providing a value of the electrical resistance of the injector. A temperature of the reducing agent at the injector is estimated as a function of the measured resistance and, when at least the temperature thus estimated is below the freezing temperature, a purge of the device is initiated.