Quiet Electromagnetic Actuator with Resilient Key

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Solution Overview

Problem

Conventional magnetic latching actuators produce high audible noise due to the rigid mounting of magnetic bases, which are struck by reciprocating members, and existing noise dampening methods like elastomers are inefficient in both compression and shear directions, leading to additional noise during base return.

Innovation Solution

An electromagnetic actuator design featuring a stator frame with a magnetic member and base separated by an air gap, where a key positioned between the flux transfer flange and stator frame absorbs energy and prevents base contact with the magnetic member, utilizing a resilient material like an O-ring or leaf spring to reduce noise and maintain magnetic latching force.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Force

If a rigid magnetic base is mounted to maximize latching forces, then the magnetic latching force is improved, but audible noise increases due to impact from reciprocating members

Engineering Contradiction:
Improvemagnetic latching forceVSAvoidaudible noise
Core Design Contradiction:
ForceVSObject-generated harmful factors

Solution Approach 1:

The patent applies beforehand cushioning by positioning a resilient key between the magnetic base and stator frame that can absorb impact energy before the base strikes the frame. The key is pre-installed in a compressed state between these components, creating a cushioning effect that reduces impact noise when the reciprocating member strikes the base, while still allowing the base to maintain its magnetic latching function.

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

Solution Approach 2:

The resilient key serves as an intermediary element between the magnetic base and stator frame. It mediates the interaction between these two components by absorbing impact forces and preventing direct contact between the base and frame during reciprocation, thereby reducing noise transmission while maintaining the magnetic circuit integrity.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Object-generated harmful factors

If elastomeric material is placed axially between base and frame for noise dampening, then audible noise is reduced, but magnetic flux density increases in the narrowed portion causing higher iron losses

Engineering Contradiction:
Improveaudible noiseVSAvoidiron losses
Core Design Contradiction:
Object-generated harmful factorsVSLoss of energy

Solution Approach 1:

The patent transitions from axial noise dampening to radial flux concentration by positioning the resilient key radially between the flux transfer flange and stator frame. This dimensional change allows the key to absorb impact energy in the radial direction without interfering with the axial magnetic flux path, thereby reducing noise without concentrating flux and causing iron losses.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The patent extracts the noise dampening function from the axial magnetic circuit path and relocates it to the radial direction. By removing the elastomeric material from the axial position between base and frame and repositioning it radially, the solution separates the noise reduction function from the magnetic flux path, preventing iron losses while maintaining noise dampening effectiveness.

Inventive Principle:
Principle #2Taking out (Extraction)

3Ease of manufacture

If the base is rigidly mounted to the stator frame, then manufacturing simplicity is improved, but noise dampening capability deteriorates

Engineering Contradiction:
Improvemounting simplicityVSAvoidimpact noise
Core Design Contradiction:
Ease of manufactureVSObject-generated harmful factors

Solution Approach 1:

The patent changes the mechanical parameter of the base mounting from rigid to resilient by introducing the resilient key. This parameter change allows the base to remain简单地 mounted to the stator frame while the resilient key provides the necessary compliance to absorb impact forces and reduce noise, maintaining ease of manufacture while improving noise dampening capability.

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

The design significantly reduces audible noise levels while maintaining required magnetic latching forces by absorbing impact energy and allowing the base to oscillate without direct contact, minimizing magnetic losses through radial flux paths and eliminating the need for additional dampening materials.

Implementation Method 1

The key is configured to absorb energy when the piston strikes the base. The key is configured to absorb energy in both the axial direction and a radial direction when the piston strikes the base.

Methodology Applied
Scientific EffectElasticity: Elasticity

Implementation Method 2

The flux transfer flange is configured to concentrate magnetic flux from the magnetic member in a radial direction into the base.

Methodology Applied
Scientific EffectMagnetic flux concentration: Magnetic Field

Implementation Method 3

The base is separated by an air gap in the axial direction from the magnetic member. The key is configured to prevent the base from contacting the magnetic member when the piston strikes the base.

Methodology Applied
Scientific EffectAir gap isolation:

Implementation Method 4

the magnetic member is a permanent magnet configured to generate the magnetic flux which also extends through the base and thereby serves to latch the piston to the base

Methodology Applied
Scientific EffectMagnetic latching: Magnetism

Data Source

PatentEP2476126B8Quiet electromagnetic actuator
Publication Date: 2018.01.03 JOHNSON ELECTRIC SA

AI summary

An electromagnetic actuator (20) comprises a stator (22), a piston (24), and a key (26). The stator comprises a stator frame (30) having an axial direction (32), the stator frame in turn comprising a magnetic member (50) and a base (52). The base (52) is separated by a gap (56) in the axial direction from the magnetic member (50) and positioned so that magnetic flux extending through the magnetic member (50) also extends through the base (52). The piston (24) is configured to reciprocate within the stator frame (30) in the axial direction (32). The key (26) is configured and position both to locate the base (52) with respect to the stator frame (and thereby provide the gap) and to absorb energy when the piston (24) strikes the base. A flux transfer flange (60) is configured to concentrate magnetic flux extending through the magnetic member (50) in a radial direction into the base (52).