Urea Sensor Thermal Coupling via Segmented PCB Design
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Solution Overview
Problem
Existing temperature sensors in urea tanks for SCR systems face accuracy issues due to self-heating from electronic components and poor thermal coupling with the urea solution, leading to inaccurate temperature measurements and potential freezing problems.
Innovation Solution
A temperature sensing unit with a substrate featuring a first region for electronic components and a second region with temperature sensors arranged in a protruding 'tower' configuration, utilizing flexible interconnects for improved thermal coupling and reduced self-heating effects, allowing for accurate and rapid temperature measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If temperature sensors are arranged in close proximity to electronic components on the same PCB, then device complexity is reduced, but measurement precision deteriorates due to self-heating from electronic components
Solution Approach 1:
The PCB is divided into two distinct regions: a first region for electronic components and a second region for temperature sensors. This spatial segmentation separates the heat-generating electronic components from the temperature sensors, eliminating self-heating interference while maintaining integration on the same PCB substrate.
Solution Approach 2:
The temperature sensors are extracted from the electronic component region and placed in a separate second region of the PCB. This extraction removes the harmful thermal influence from the measurement location while keeping the sensor integrated into the overall device structure.
2Reliability
If potting material is used to cover the PCB with temperature sensor, then device protection is improved, but thermal coupling between fluid and temperature sensor deteriorates
Solution Approach 1:
The potting material coverage is applied selectively: it covers the first region containing electronic components for protection, but deliberately excludes the second region containing temperature sensors. This local differentiation allows protected electronics while maintaining direct thermal coupling between the urea solution and temperature sensors.
Solution Approach 2:
The PCB and potting structure are segmented into two zones: a protected zone (first region) with electronics covered by potting material, and an exposed zone (second region) with temperature sensors directly exposed to the urea solution for optimal thermal contact.
3Measurement precision
If temperature sensing units are provided as separate components connected via plug connector, then measurement precision is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The temperature sensors are merged with the PCB structure by mounting them directly in the second region of the PCB. This integration combines the benefits of precise temperature sensing with simplified assembly, eliminating the need for separate temperature sensing units and plug connectors while maintaining measurement accuracy through proper thermal coupling design.
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 provides enhanced thermal coupling with the urea solution, improving measurement accuracy and response times while simplifying the manufacturing process and reducing costs, enabling effective monitoring of urea solution temperatures to prevent freezing and ensure efficient NOx breakdown.
Implementation Method 1
a temperature sensor and a substrate with a first region and a second region. The temperature sensor is arranged in the second region
Data Source
AI summary
A temperature sensing unit includes a temperature sensor and a substrate including a first region and a second region. The temperature sensor is arranged in the second region. The second region extends away from the first region.