PTC Starter Isolation Structure for Fragment-Safe Disconnection

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Solution Overview

Problem

Prior PTC starters fail to completely disconnect the electronic element from the circuit when it ruptures, leading to potential short circuits and motor burnout due to the presence of tiny granular fragments, which existing designs are unable to prevent effectively.

Innovation Solution

A PTC starter design featuring a housing with a thermistor and elastic element, where the elastic element is used to push away ruptured thermistor fragments and an isolation structure prevents these fragments from entering the disconnection point, ensuring a reliable and safe disconnection.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a PTC starter is used to complete the starting process, then the motor can start and operate normally, but the PTC component may deteriorate and rupture into fragments causing short circuits and motor burnout

Engineering Contradiction:

Improvemotor operation reliabilityVSAvoidfragment-induced short circuit and motor burnout

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The housing is divided into separate compartments: a first cavity for receiving the PTC component and a second cavity for receiving the elastic element and contact parts. This segmentation prevents fragments from the PTC component from reaching the electrical contact areas, thereby eliminating the harmful effect while maintaining the starting function.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The harmful fragments are extracted from the circuit path by containing them in a separate first cavity. The elastic element and contact parts are positioned in a second cavity, physically removing the possibility of fragment interference with electrical connections.

Inventive Principle:

Principle #2Taking out (Extraction)

2Device complexity

If existing designs allow thermistor fragments to remain in the circuit, then the structure remains simple, but short circuits and motor burnout cannot be prevented

Engineering Contradiction:

Improvestarter structure simplicityVSAvoidcircuit safety

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

An isolation wall is introduced as an intermediary structure between the first cavity and second cavity. This wall acts as a barrier that prevents fragment migration while maintaining the structural integrity and electrical isolation between compartments.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Object-affected harmful factors

If the elastic element is used to push away ruptured thermistor fragments, then fragment dispersion is prevented, but the device complexity increases

Engineering Contradiction:

Improvefragment interference with disconnectionVSAvoidstarter component count

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The elastic element automatically pushes fragments away from the contact area when the PTC component ruptures, providing self-service protection without requiring external intervention or complex control mechanisms. The elastic force naturally directs fragments into the first cavity, preventing interference with the disconnection process.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The elastic element provides dynamic response to fragment generation, automatically adjusting its position to push fragments away from critical areas. This dynamic mechanism adapts to the rupture event without requiring complex control systems.

Inventive Principle:

Principle #15Dynamics

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 design effectively prevents short circuits by ensuring that thermistor fragments do not interfere with the disconnection process, enhancing the safety and reliability of the PTC starter.

Implementation Method 1

When the thermistor is in a normal state, the elastic element is in an elastic deformation state... After the thermistor ruptures, the elastic element resets, and the connecting piece is moved under a reset effect to push away the ruptured thermistor

Methodology Applied

Scientific EffectElastic deformation: Elasticity

Implementation Method 2

When starting, due to the thermal effect of the current, the temperature of PTC component rises in a short period. After reaching the Curie point, the resistance of the PTC component is quickly increased to tens kilo-ohms or more

Methodology Applied

Scientific EffectThermal effect: Joule Heating

Data Source

PatentUS11823820B2PTC starter

Publication Date: 2023.11.21 HANGZHOU STAR SHUAIER ELECTRIC APPLIANCE

AI summary

A PTC starter is provided. A first pin is electrically connected to a first electrode of a thermistor. The thermistor and an elastic element are arranged in respective mounting cavities. The elastic element is provided with a connecting piece, through which a second pin is electrically connected to or disconnected from a second electrode of the thermistor. In a normal state of the thermistor, the elastic element is in an elastic deformation state, a first contact part and a second contact part of the elastic element are in electrical contact with the second electrode of the thermistor and the second pin respectively. After the thermistor ruptures, the elastic element resets, which causes the connecting piece to move so that the second contact part of the elastic element detaches from the second pin. An isolation structure is provided between the thermistor mounting cavity and the elastic element mounting cavity.