Gas Sensor Contact Member With Leaf Spring Abutting Part

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Solution Overview

Problem

Conventional gas sensors face issues with stable retention of the sensor element and maintenance of electric continuity due to reduced surface pressure and potential plastic deformation in the contact area, leading to contact failures.

Innovation Solution

The gas sensor employs a contact member with retaining members that include a cantilever-beam-shaped leaf spring abutting part, which provides a restoring force to maintain a stable contact with the sensor element, utilizing a compressive deformation of a fixing metal fixture and caulking ring to secure the sensor element within the housing, ensuring a higher retaining force and preventing nonconductor film formation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Area of stationary object

If the convex part is elastically deformed to increase contact area with the electrode terminal, then the contact area is increased, but the surface pressure is reduced and nonconductor film formation occurs leading to contact failure

Engineering Contradiction:
Improvecontact areaVSAvoidcontact stability
Core Design Contradiction:
Area of stationary objectVSReliability

Solution Approach 1:

The patent changes the shape parameter of the retaining member from a simple convex form to a specific geometric configuration (including inclined surfaces and flat contact surfaces). This parameter change allows the contact area to be sufficiently large for reliable electrical contact while maintaining adequate surface pressure through the optimized geometry, preventing nonconductor film formation and contact failure.

Inventive Principle:
Principle #35Parameter changes

2Force

If the convex part is elastically deformed to retain the sensor element, then the retention force is provided, but the elastic area is small and plastic deformation occurs reducing surface pressure

Engineering Contradiction:
Improveretention forceVSAvoidelastic deformation capacity
Core Design Contradiction:
ForceVSStrength

Solution Approach 1:

The retaining member is designed with dynamic characteristics that allow it to elastically deform during sensor element insertion and then maintain a stable retained state. The specific geometric configuration enables the member to provide sufficient retention force through controlled elastic deformation while avoiding plastic deformation, thus maintaining surface pressure and preventing contact failure.

Inventive Principle:
Principle #15Dynamics

3Device complexity

If the retaining member is designed with simple convex parts, then the device complexity is low, but the contact reliability and retention stability are insufficient

Engineering Contradiction:
Improveretaining member structureVSAvoidcontact continuity
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The retaining member features localized geometric variations with different surface characteristics at different locations. The inclined surfaces facilitate sensor element insertion, while the flat contact surfaces provide stable electrical contact. This local quality differentiation ensures reliable contact continuity and retention stability without significantly increasing overall device complexity.

Inventive Principle:
Principle #3Local quality

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

This configuration stabilizes the retention of the sensor element and maintains a stable electric continuity with the electrode terminal, reducing the occurrence of contact failures and ensuring reliable operation.

Implementation Method 1

utilizing a compressive deformation of a fixing metal fixture and caulking ring to secure the sensor element within the housing

Methodology Applied
Scientific EffectElastic deformation: Elasticity

Data Source

PatentEP2500721B1Gas sensor, contact member of gas sensor, and sensor element holding member for contact member of gas sensor
Publication Date: 2020.06.17 NGK INSULATORS LTD
  • EP2500721B1 patent drawingFigure 1(a)~1(b)
  • EP2500721B1 patent drawingFigure 2
  • EP2500721B1 patent drawingFigure 3

AI summary

To provide a gas sensor which can stably carry out a retention of a sensor element by a contact member and a reservation of an electric continuity between the sensor element and the contact member. A gas sensor is provided with a sensor element, and a contact member having an insertion port in which the sensor element is inserted and retained to obtain an electric connection with the sensor element. The contact member is provided with a plurality of sensor element retaining members which respectively have a plurality of abutting parts abutting on the sensor element, at least a part of a plurality of abutting parts is a first abutting part which has a leading end part formed as a linear shape or a point-like shape, and the leading end part of the first abutting part is a free end part which applies an elastic force to the sensor element while having point contact or line contact with the sensor element.