Cam Follower Mechanism for Electrical Control Device

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Solution Overview

Problem

Existing mechanisms with sliding members, such as those used in electrical control devices, face manufacturing difficulties and performance issues due to friction between a thin metal connecting rod and a plastic cam, leading to wear and reduced longevity.

Innovation Solution

A mechanism where the connecting rod is in contact with the cam surface only when necessary, using a spring to urge the slider transversely against an island, reducing friction and wear by eliminating the need for strong pressure on the cam surface, and featuring a cylindrical barrel to hold the spring outside the cam track.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the connecting rod is urged towards the cam surface to ensure non-return blocking, then the slider is prevented from moving in the wrong direction, but the friction between the rod and cam increases causing wear and reduced longevity

Engineering Contradiction:
Improvenon-return blockingVSAvoidmechanism longevity
Core Design Contradiction:
ReliabilityVSDuration of action of stationary object

Solution Approach 1:

The patent introduces a cam follower as an intermediary element between the connecting rod and the cam surface. The follower rides along the cam profile and transmits motion to the connecting rod, eliminating direct contact between the rod and cam. This mediator reduces friction and wear while maintaining the non-return blocking function through the geometric design of the cam profile and follower arrangement.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent replaces the direct mechanical contact system (rod pressing against cam) with a rolling contact system using the cam follower. The follower is designed to roll along the cam surface rather than slide, substituting sliding friction with rolling friction. This mechanical substitution significantly reduces wear on both the cam and connecting rod while maintaining the necessary blocking function.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Stability of the object's composition

If strong pressure is applied against the cam surface to maintain slider positioning, then the slider remains stable in position, but the friction increases requiring the magnetic circuit to overcome greater resistance

Engineering Contradiction:
Improveslider positioning stabilityVSAvoidmagnetic circuit energy consumption
Core Design Contradiction:
Stability of the object's compositionVSUse of energy by moving object

Solution Approach 1:

The cam follower acts as a mediator that maintains slider positioning stability through rolling contact rather than sliding contact. The follower's roller element maintains constant contact with the cam profile, providing stable positioning without requiring strong pressing forces. This eliminates the need for high pressure while maintaining positioning stability, thereby reducing the energy required by the magnetic circuit.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent employs a dynamic positioning system where the cam follower automatically adjusts its position along the cam profile to maintain optimal contact. Rather than applying constant strong pressure, the system uses the geometric constraints of the cam-follower mechanism to dynamically maintain slider positioning. This dynamic approach reduces energy consumption by eliminating the need for excessive forcing forces.

Inventive Principle:
Principle #15Dynamics

3Ease of operation

If the slider is biased transversely against the cam surface to engage on the correct path, then the slider follows the intended cam path, but the friction between thin metal rod and plastic cam increases causing wear

Engineering Contradiction:
Improveslider path engagementVSAvoidmachining complexity of slider end
Core Design Contradiction:
Ease of operationVSEase of manufacture

Solution Approach 1:

The cam follower serves as an intermediary that simplifies the slider end geometry. Instead of machining a complex curved surface on the slider to engage the cam profile directly, the slider simply carries the follower which contains the rolling element. This mediator transfers the path-following function from the slider to the follower, greatly simplifying slider manufacturing while ensuring correct path engagement through the follower's roller contact with the cam.

Inventive Principle:
Principle #24Intermediary (Mediator)

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 simplifies manufacturing, reduces wear, and enhances the longevity of the mechanism by minimizing friction, allowing smoother slider movement and improved performance.

Implementation Method 1

a spring which urges the slider against the cam surface

Methodology Applied
Scientific EffectElasticity: Elasticity

Implementation Method 2

a magnetic circuit formed of a coil, one armature of which is movable and connected to the member

Methodology Applied
Scientific EffectMagnetic force: Magnetism

Implementation Method 3

The mechanism also comprises a heart-shaped cam having an island around which extends a cam path in which the slider is adapted to move

Methodology Applied
Scientific EffectMechanical leverage: Lever

Data Source

PatentEP1901327B1Mechanism with two stable positions and electrical control device comprising same
Publication Date: 2010.11.17 LEGRAND FRANCE SA
  • EP1901327B1 patent drawingFigure 1
  • EP1901327B1 patent drawingFigure 2~3
  • EP1901327B1 patent drawingFigure 4~5

AI summary

The mechanism has an actuating unit (4) sliding between advanced and remote positions. A connecting rod (21) has a slide (35) moved on a cam surface (37), and a central block (40) emerges from the cam surface. A cam channel is formed around the island and has two paths for the slide, where the channel is flat. A backstop unit blocks access of the slide to one of the paths, and has a spring branch (67) extending transversal to the channel at a junction between the paths in case of absence of stress on the slide. An independent claim is also included for an electrical control device comprising a mechanism for connecting and electrically insulating terminals.