Isolated Terminal Temperature Sensing With Surface Material Patch
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Solution Overview
Problem
Current temperature sensing methods for electrical terminal connectors face limitations due to the need for electrical isolation, which adds thermal resistance and capacitance, leading to reduced accuracy and longer response times, and embedded sensors reduce pin cross-sectional area, increasing electrical resistance and ohmic heat generation.
Innovation Solution
An external circuit and method that applies a material patch to the electrical terminal surface with minimal thermal mass, allowing for remote temperature sensing without increasing the measurement system time constant or reducing the pin cross-sectional area, using thermochromic materials or polymer matrices with magnetic particles to detect temperature changes through photocurrent or eddy current losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional sensors (RTDs or thermocouples) are used for temperature sensing, then electrical isolation is achieved, but measurement precision and response time deteriorate due to added thermal resistance and capacitance
Solution Approach 1:
A material patch serves as an intermediary between the electrical terminal and the remote sensing circuit. The patch is applied directly to the pin surface and transfers thermal information without requiring electrical contact, thereby maintaining electrical isolation while minimizing thermal resistance and capacitance additions.
Solution Approach 2:
The patent replaces traditional electrical/thermal contact-based sensing (RTDs, thermocouples) with an optical sensing mechanism. The material patch converts temperature changes into optical signals that can be detected remotely, eliminating the need for physical electrical contact and associated thermal interference.
2Measurement precision
If embedded sensors (nitinol wire helix or phase change wax capsule) are used, then response time and measurement accuracy improve, but pin cross-sectional area is reduced leading to increased electrical resistance and ohmic heat generation
Solution Approach 1:
The sensing function is extracted from the electrical terminal itself and placed in a separate material patch applied to the surface. This allows the terminal to maintain its full cross-sectional area and electrical properties while the patch performs the temperature sensing function externally.
Solution Approach 2:
The patent transitions from volumetric embedded sensors (occupying space within the pin) to a surface-based solution. The material patch operates in a different dimensional space (on the surface rather than inside), eliminating the trade-off between sensing accuracy and electrical conductivity.
3Reliability
If material patch with significant thermal mass is applied to electrical terminal, then sensing capability is provided, but measurement system time constant increases due to added thermal capacitance
Solution Approach 1:
The material patch is implemented as a thin film or coating applied to the terminal surface. This thin-film approach provides the necessary sensing capability while minimizing thermal mass and thermal capacitance, thereby keeping the response time constant low.
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
Enables accurate and fast temperature sensing without adding thermal mass or reducing the pin's cross-sectional area, optimizing current flow and avoiding connector damage by providing electrical isolation and maintaining high measurement accuracy.
Implementation Method 1
generating a magnetic field based on the thermal expansion of a polymer matrix, the magnetic field is a non-linear function of temperature
Implementation Method 2
exciting the electrically conductive magnetic particles with an AC magnetic field to cause eddy currents to flow within the electrically conductive magnetic particles
Implementation Method 3
wherein when the polymer matrix is below the designed transition temperature and the electrically conductive magnetic particles are in close mechanical contact the eddy currents will flow through the electrically conductive magnetic particles and the polymer matrix and the losses will be significantly higher
Implementation Method 4
reflecting photons of lower energy than a bandgap of the detector when the temperature of the terminal is in an acceptable range, whereby an electric current induced by the action of photocurrent in the detector is low
Data Source
AI summary
A method of detecting temperature of an electrical terminal. The method includes: applying a material patch to a surface of the electrical terminal, the material patch containing a polymer matrix with a polymeric positive temperature coefficient material which contains a mixture of electrically conductive magnetic particles, whereby the material patch does not appreciably increase the electrical resistance or thermal capacitance of the electrical terminal; and remotely sensing a change in the material patch with an electrically isolated circuit which is external to the electrical terminal to determine if the electrical terminal is operating at a safe temperature to optimize current flow across the electrical terminal.