Bimetal Switch Temperature-Sensing Tape for Flexible Trip Thresholds

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Solution Overview

Problem

Existing temperature-sensing devices for protecting electrical devices and batteries from overtemperature conditions require multiple sensors with different trip temperatures to accommodate changing thermal protection requirements, which can be cumbersome and inefficient.

Innovation Solution

A temperature-sensing tape with a plurality of flexible conductor portions and a sensor array comprising at least one temperature-sensing element with a bimetallic switch, allowing for flexible and adaptable thermal protection by adjusting the switch temperature to suit various applications.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If multiple sensors with different trip temperatures are used to accommodate changing thermal protection requirements, then the adaptability to different temperature thresholds is improved, but the device complexity and quantity of components increase

Engineering Contradiction:
Improveadaptability to different temperature thresholdsVSAvoidquantity of sensors required
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent applies parameter changes by utilizing a single PTC sensor whose trip temperature can be adjusted through changes in ambient pressure. By varying the pressure applied to the sensor, the trip temperature can be tuned to match different maximum operating temperature requirements of various devices, eliminating the need for multiple fixed-temperature sensors.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The invention makes a single PTC sensor universal by enabling it to serve multiple temperature protection functions. The sensor can be configured to protect different devices (laptops, smartphones, batteries, etc.) with different maximum operating temperatures simply by adjusting the ambient pressure, making one sensor replace multiple specialized sensors.

Inventive Principle:
Principle #6Universality (Multi-functionality)

2Reliability

If PTC sensors are designed to trip at a targeted temperature characteristic of the PTC material, then the measurement precision and reliability of temperature protection is improved, but the adaptability to changing product temperature requirements deteriorates

Engineering Contradiction:
Improvereliability of temperature protectionVSAvoidadaptability to changing temperature requirements
Core Design Contradiction:
ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent resolves this contradiction by introducing ambient pressure as a controllable parameter that modifies the trip temperature of the PTC sensor. The sensor maintains its reliable PTC characteristics while its operating temperature point can be shifted by applying different pressures, allowing the same sensor to reliably protect devices with different temperature requirements.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The invention introduces ambient pressure as an intermediary mechanism between the fixed PTC material properties and the variable temperature requirements. This intermediary allows the sensor to adapt to different temperature thresholds without compromising the inherent reliability of the PTC effect, as the pressure merely shifts the operating point rather than altering the fundamental sensing mechanism.

Inventive Principle:
Principle #24Intermediary (Mediator)

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 temperature-sensing tape provides effective and adaptable thermal protection by offering a digital response to temperature changes, allowing for precise control of electrical resistance and preventing damage from overtemperature conditions across a wide range of temperatures.

Implementation Method 1

the at least one temperature-sensing element comprises a bimetallic switch

Methodology Applied
Scientific EffectBimetallic switch: Bi-Metallic Strip

Implementation Method 2

temperature-sensing devices that can be used to measure temperature variations at discrete locations on the surface of an electrical device

Methodology Applied
Scientific EffectTemperature sensing: Thermal Expansion

Data Source

PatentEP4198472B1Temperature-sensing tape based upon bimetal switch, and method of temperature control
Publication Date: 2025.05.21 LITTELFUSE INC
  • EP4198472B1 patent drawingFigure 1A~1B
  • EP4198472B1 patent drawingFigure 2A~2C
  • EP4198472B1 patent drawingFigure 3~4

AI summary

A temperature-sensing tape including a flexible, electrically insulating substrate, a plurality of temperature-sensing elements disposed on the substrate, wherein a temperature-sensing element includes a bimetallic switch.