Injector Pressure Sensor for Liquid Reducing Agent Thawing
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Solution Overview
Problem
Existing systems face challenges in efficiently conveying and thawing liquid reducing agents, such as aqueous urea solutions, at low temperatures, leading to incomplete thawing and vacuum issues during aspiration, which affects the reliable addition of reducing agents to exhaust gas flows in motor vehicles.
Innovation Solution
An injector device with an integrated pressure sensor and a chamber at the tank bottom houses a supply unit, including a heater and pump, allowing precise pressure measurement and efficient thawing of the reducing agent, ensuring bubble-free conveyance and accurate fill level monitoring.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a heater is placed at the tank bottom to thaw frozen reducing agent, then the reducing agent at the tank bottom can be thawed, but a thick covering of ice remains around the removal point above the heater
Solution Approach 1:
The heating system is segmented into multiple heating zones: a first heating element at the tank bottom and a second heating element at the tank outlet. This segmentation allows independent control of thawing in different regions, ensuring complete ice removal at both the storage zone and the critical outlet area where ice coverage previously blocked flow.
Solution Approach 2:
The system performs preliminary thawing action by heating the reducing agent before it reaches the outlet point. The controller activates heating elements in advance when freeze conditions are detected, preventing ice formation at the outlet and ensuring the reducing agent is fully liquid before aspiration begins.
2Volume of stationary object
If the liquid reducing agent is removed through the tank bottom, then storage space is optimized, but frozen reducing agent creates vacuum that normal pumps cannot overcome
Solution Approach 1:
The system changes the operational parameters of the pump based on temperature conditions. When the reducing agent is frozen or near-freezing, the controller adjusts pump operation modes or activates alternative delivery mechanisms to overcome the vacuum pressure created by ice blockage, ensuring continuous operation across varying temperature ranges.
Solution Approach 2:
The system performs preliminary thawing action by heating the reducing agent before it reaches the outlet point. The controller activates heating elements in advance when freeze conditions are detected, preventing ice formation at the outlet and ensuring the reducing agent is fully liquid before aspiration begins.
3Reliability
If anti-freeze agent is added to lower the freezing point to -40°C, then freezing prevention is improved, but reliable reduction of nitrogen oxides at very low temperatures requires additional thawing measures
Solution Approach 1:
The system uses the thermal energy from the exhaust gas itself to thaw the reducing agent. The exhaust gas flowing through the catalytic converter provides heat that is transferred to the reducing agent in the tank or supply lines, enabling self-thawing without requiring separate external heating systems.
4Measurement precision
If pressure sensors are integrated in the injector, then pressure measurement precision is improved, but device complexity increases
Solution Approach 1:
The pressure sensor is integrated directly into the injector structure, merging the measurement function with the injection component. This consolidation eliminates separate pressure measurement devices and their associated piping, reducing overall system complexity while achieving precise pressure measurement at the critical injection point.
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
The solution enables reliable and efficient thawing and conveyance of liquid reducing agents, even at low temperatures, ensuring effective nitrogen oxide reduction in exhaust gases by providing precise pressure control and monitoring, and facilitating complete thawing and removal of the agent.
Implementation Method 1
it has been found in that case that the frozen reducing agent can indeed be thawed through the use of a heater at the tank bottom
Implementation Method 2
The aspiration of the liquefied reducing agent leads, however, to a vacuum, against which the pumps used normally in that instance cannot function
Data Source
AI summary
A device includes an injector for a liquid having at least one pressure sensor, preferably an integrated pressure sensor. The device is used, in particular, for adding liquid reducing agent to an exhaust gas line of a motor vehicle. A configuration having the device and methods of using the device and the configuration are also provided.