Temperature sensor and cooking appliance

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Solution Overview

Problem

Temperature sensors used in cookware face disconnection issues at the joining portion between the heat-sensitive body and lead wire due to compressive and tensile loads applied during cooking, leading to potential disconnection over time.

Innovation Solution

Incorporating a connecting wire with a twisted core wire and a smaller wire diameter than the lead wire, along with an insulating covering, to allow for elastic deformation and distribute impact loads, preventing disconnection by relaxing the load through the core wire's deformable region.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the heat collecting body is pressed down by the cookware, then the temperature detection function is activated, but the joining portion between the heat-sensitive body and lead wire experiences compressive load that may cause disconnection

Engineering Contradiction:
Improveconnection reliabilityVSAvoidjoining portion strength
Core Design Contradiction:
ReliabilityVSStrength

Solution Approach 1:

The patent applies beforehand cushioning by introducing a deformable region in the lead wire that can absorb impact loads before they reach the joining portion. This deformable region acts as a cushion that undergoes elastic deformation when the heat collecting body is pressed down by cookware, preventing the full impact force from being transmitted to the vulnerable joining portion between the heat-sensitive body and lead wire, thereby preventing disconnection before it can occur.

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

2Ease of operation

If the heat collecting body is pressed up by elastic force after cookware removal, then the movable body returns to initial position, but tensile load is applied to the joining portion that may cause disconnection

Engineering Contradiction:
Improvemovable body reciprocityVSAvoidjoining portion strength
Core Design Contradiction:
Ease of operationVSStrength

Solution Approach 1:

The deformable region with elastic properties provides beforehand cushioning during the upward movement phase as well. When the heat collecting body is pressed up by the elastic force after cookware removal, the deformable region undergoes elastic deformation in tension, absorbing the tensile load before it can reach the joining portion. This prevents disconnection caused by repetitive tensile loads during the return motion.

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

3Strength

If the lead wire has sufficient strength to resist impact load, then disconnection is prevented, but the wire cannot elastically deform to relax the impact load

Engineering Contradiction:
Improvelead wire strengthVSAvoidwire deformability
Core Design Contradiction:
StrengthVSAdaptability or versatility

Solution Approach 1:

The patent applies local quality by creating a deformable region with specific elastic properties at a particular location in the lead wire, while the rest of the wire maintains its original strength characteristics. This localized deformable region allows the wire to exhibit different mechanical properties in different segments: the deformable region can elastically deform to absorb impact loads, while the stronger portions of the wire maintain structural integrity and electrical conductivity.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent applies parameter changes by modifying the physical parameters of the lead wire in the deformable region, such as changing the wire diameter, material composition, or structural configuration to reduce the elastic modulus or increase flexibility in that specific region. This parameter change enables the deformable region to undergo elastic deformation under impact loads while the rest of the wire maintains its original strength parameters.

Inventive Principle:
Principle #35Parameter changes

4Reliability

If the connecting wire has longer total extension, then the impact load is relaxed, but the wire structure becomes more complex

Engineering Contradiction:
Improveimpact load relaxationVSAvoidwire structure complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies segmentation by dividing the lead wire into distinct functional segments: a rigid portion that maintains structural integrity and electrical connection, and a deformable region that absorbs impact loads through elastic deformation. This segmentation allows the wire to achieve impact load relaxation without requiring a completely complex wire structure, as the deformable region is a simple localized segment with modified properties rather than a complex overall structure.

Inventive Principle:
Principle #1Segmentation

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 effectively prevents disconnection of the core wire from the heat-sensitive body by allowing the connecting wire to elastically deform under impact loads, maintaining the connection state between the heat-sensitive body and lead wire.

Implementation Method 1

elastic force is applied to the heat collecting body upward by a coil spring

Methodology Applied
Scientific EffectElastic force: Elasticity

Implementation Method 2

detects the temperature of the cookware by receiving the heat transferred from the heat collecting body

Methodology Applied
Scientific EffectHeat transfer: Conduction (thermal)

Implementation Method 3

a deformable region having a strength lower than that of the first core wire... allowing the connecting wire to elastically deform under impact loads

Methodology Applied
Scientific EffectElastic deformation: Elasticity

Data Source

PatentEP3783326B1Temperature sensor and cooking appliance
Publication Date: 2024.02.14 SHIBAURA ELECTRONICS CO LTD
  • EP3783326B1 patent drawingFigure 1A~1B
  • EP3783326B1 patent drawingFigure 2A~2B
  • EP3783326B1 patent drawingFigure 3A~3B

AI summary

This temperature sensor 1 comprises: a sensor element having a heat-sensitive body 11 that contacts a detection target, a pair of lead wires 13, 13 connected to the heat-sensitive body, and relay wires 30, 30 connected to the respective lead wires 13, 13; and a sensor holding body 40 having a fixed body 51, the position of which is fixed to a target appliance, and a movable body 41 that supports the heat-sensitive body 11 of the sensor element and moves back and forth relative to the fixed body 51. Each lead wire 13 comprises a core wire 14 made of a single wire, and an insulating cover 15 that covers the core wire 14, and each relay wire comprises a core wire 31 made of a twisted wire, and an insulating cover 33 that covers the core wire 31. A conducting wire constituting the twisted wire of the lead wire 13 has a smaller wire diameter than the single wire constituting the lead wire 13.