Contact Bushing Sleeve Prevents Spring Relaxation

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Solution Overview

Problem

Existing contact sockets experience a reduction in contact force over time due to the relaxation of radially bent contact tongues, leading to unreliable electrical connections after repeated use.

Innovation Solution

The contact tongues are bent radially inward in their central region, with a sleeve forming a double truncated cone shape to maintain constant contact force, and radially outward lugs fix the sleeve immovably, ensuring the sleeve acts as an additional resilient element to prevent spring force relaxation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Force

If contact tongues are bent radially inwards to provide elastic contact force, then insertion force is reduced and contact is established, but spring force relaxes over time leading to reduced contact force and unreliable connection

Engineering Contradiction:
Improvecontact forceVSAvoidduration of constant contact force
Core Design Contradiction:
ForceVSDuration of action of stationary object

Solution Approach 1:

The contact tongues are designed to be elastically deformable, allowing them to dynamically adapt to the contact pin during insertion and maintain continuous contact pressure. The elastic material enables the contact tongues to recover their original position after deformation, ensuring sustained contact force over time rather than static rigid contact.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent utilizes the elastic properties of the contact tongues by selecting appropriate material parameters (elastic modulus, yield strength) and geometric parameters (thickness, length, bend radius) to optimize the spring force characteristics. By carefully controlling these parameters, the contact tongues maintain constant contact force over extended periods despite repeated insertion cycles.

Inventive Principle:
Principle #35Parameter changes

2Ease of operation

If contact tongues are made elastic to reduce insertion force, then ease of operation is improved, but contact force reliability deteriorates after repeated use

Engineering Contradiction:
Improveinsertion forceVSAvoidcontact reliability
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The elastic contact tongues provide dynamic adaptation during insertion, automatically adjusting to the contact pin's position and shape. This dynamic behavior reduces the force required for insertion while ensuring reliable contact establishment. The elastic deformation allows the contact tongues to conform to manufacturing tolerances and wear variations, maintaining reliability over time.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The elastic contact tongues act as a cushioning element that absorbs insertion shocks and mechanical stresses before they can damage the electrical contact. This beforehand cushioning protects the contact interface from damage during repeated insertion cycles, preventing premature failure and maintaining reliable electrical connection throughout the product's service life.

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

3Reliability

If contact tongues are bent to establish contact, then electrical contact is achieved, but contact force reduces over time due to spring force relaxation

Engineering Contradiction:
Improveelectrical contact reliabilityVSAvoidcontact force magnitude
Core Design Contradiction:
ReliabilityVSForce

Solution Approach 1:

The elastic contact tongues continuously exert restoring force as they return to their original bent position after being compressed by the contact pin. This dynamic elastic recovery ensures that contact force is maintained throughout the operational life of the connector, preventing the force reduction that would occur with rigid or plastic deformation contacts.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent optimizes the geometric parameters of the contact tongues (such as the bend radius, thickness, and length) to maximize the spring force while maintaining reliable electrical contact. By carefully selecting these parameters, the contact tongues provide sufficient contact force to ensure low electrical resistance and reliable connection, while the elastic material prevents permanent deformation and force loss over time.

Inventive Principle:
Principle #35Parameter changes

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 design maintains a constant contact force and low electrical resistance between the contact pin and socket, preventing contact loss and ensuring reliable connections over a long period.

Implementation Method 1

The sleeve consists of an elastically deformable material. By inserting the contact pin into the contact socket, the contact tongues are pushed slightly radially outwards. This pressure is also transferred to the sleeve, so that the relaxation of the spring force of the contact tongues - and thus a loss of contact between socket and plug - is prevented.

Methodology Applied
Scientific EffectElasticity: Elasticity

Implementation Method 2

The contact tongues are bent in the direction of the longitudinal axis of the contact socket, ie in the radial direction of the cylinder body, in order to establish physical contact with the contact pin. The contact socket according to the invention has a low electrical contact resistance to the contact pin.

Methodology Applied
Scientific EffectElectrical conduction: Conduction (electrical)

Data Source

PatentEP2333906B1Contact bushing for holding a contact pin
Publication Date: 2014.01.22 HARTING ELECTRIC GMBH & CO KG
  • EP2333906B1 patent drawingFigure 1~2
  • EP2333906B1 patent drawingFigure 3~4

AI summary

The socket (1) has a plug-in area (SB) defined in a cylindrical body (10) comprising a set of axial grooves (8) through which a contact stud (4) for contacting an electrical contact pin is formed. A sleeve (5) is arranged on the contact stud in form-fit manner. A portion of the contact stud is bent inwardly, so that the sleeve obtains a duplex truncated cone form and exerts force on the contact stud. The sleeve is aligned orthogonal to a longitudinal axis of the stud. The stud has a flange (4a) along a circular insertion opening for rigidly fixing the sleeve, where the flange points outwardly. The sleeve is made of elastic, deformable material.