Au-Ni Alloy Contacts for Limit Switches

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Solution Overview

Problem

Conventional electric contact materials in limit switches suffer from deteriorated anti-stick properties and reduced vibration and shock resistance when subjected to large contact loads, and vice versa when contact loads are reduced.

Innovation Solution

The use of an Au—Ni metal alloy with no less than 97% Au by weight for the fixed and movable contacts in a limit switch, which increases the contact load and reduces the material hardness to enhance contact reliability and prevent sticking.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional electric contact material is used in a limit switch, then the anti-stick property deteriorates when a large contact load is applied, but the contact reliability and vibration/shock resistance deteriorate when the contact load is reduced

Engineering Contradiction:

Improvecontact reliabilityVSAvoidanti-stick property

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent changes the material composition parameters by using an Au-Ni alloy with no less than 97% Au by weight, which fundamentally alters the physical and chemical properties of the contact material. This parameter change enables the contacts to maintain both high contact reliability and superior anti-stick properties simultaneously, resolving the contradiction between reliability and anti-stick performance under varying contact loads

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent employs a composite Au-Ni alloy material that combines the advantages of both gold (high conductivity, corrosion resistance) and nickel (hardness, wear resistance). This composite material structure allows the contacts to exhibit both excellent contact reliability and anti-stick properties, eliminating the trade-off present in conventional single-material contacts

Inventive Principle:

Principle #40Composite materials

2Reliability

If the contact load is increased to improve contact reliability, then the anti-stick property deteriorates, but if the contact load is reduced, then the vibration and shock resistance deteriorates

Engineering Contradiction:

Improvecontact reliabilityVSAvoidvibration and shock resistance

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The patent changes the material parameters by adopting an Au-Ni alloy with specific composition (no less than 97% Au), which modifies the mechanical properties including hardness and elasticity. This parameter change enables the contact to maintain adequate contact load while resisting vibration and shock, resolving the contradiction between reliability and mechanical strength

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

This principle is not directly applicable to this patent as the invention focuses on material composition optimization rather than replacing contacts with disposable components

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

Data Source

PatentUS9859067B2Limit switch

Publication Date: 2018.01.02 OMRON CORP

AI summary

A limit switch includes fixed contacts and a movable contact, the fixed contacts and the movable contact formed from an Au—Ni metal alloy of no less than 97% Au by weight. The limit switch detects position, change, movement, number of passes, or the like and outputs an “on” signal or an “off” signal depending on whether a detection occurred.