Linear Motor Vibration Cancellation via Secondary Mass

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Solution Overview

Problem

Existing linear motors used in oral hygiene devices face challenges in reducing vibrations transmitted to the housing, which can lead to discomfort and inefficiency in oscillatory movements.

Innovation Solution

A linear motor design incorporating a secondary mass and coupling spring assemblies, where the armature and secondary mass move with opposite amplitudes, effectively canceling out vibrations and optimizing the construction volume by using asymmetric armature arrangements and spiral-shaped leaf springs for efficient energy transfer.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If a conventional linear motor design is used, then the motor can provide linear oscillation, but vibrations are transmitted to the housing causing discomfort and inefficiency

Engineering Contradiction:

Improvevibrations transmitted to housingVSAvoidoscillatory movement efficiency

Core Design Contradiction:

Object-affected harmful factorsVSEase of operation

Solution Approach 1:

The patent introduces a secondary mass that moves in opposition to the armature's motion. When the armature moves in one direction, the secondary mass moves in the opposite direction, creating counterbalancing forces that cancel out vibrations transmitted to the housing. This counterweight mechanism directly addresses the harmful vibrations while maintaining oscillatory movement efficiency.

Inventive Principle:

Principle #8Anti-weight (Counterweight)

Solution Approach 2:

The armature is designed with an asymmetric arrangement where the permanent magnet arrangement is offset from the longitudinal axis. This asymmetric configuration allows for optimized magnetic field interaction and force generation, improving the efficiency of oscillatory movements while enabling the vibration cancellation mechanism to function effectively.

Inventive Principle:

Principle #4Asymmetry

2Object-affected harmful factors

If vibration reduction mechanisms are added to the linear motor, then vibrations are reduced, but the construction volume increases

Engineering Contradiction:

Improveresidual vibrationsVSAvoidmotor construction volume

Core Design Contradiction:

Object-affected harmful factorsVSVolume of moving object

Solution Approach 1:

The secondary mass is integrated into the existing motor structure rather than being added as a separate external component. The coupling spring assemblies are incorporated within the motor housing, merging the vibration reduction function with the existing construction. This integration allows vibration cancellation without significantly increasing the overall motor volume.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The coupling spring assemblies are nested within the motor structure, with the secondary mass positioned inside the housing. The spring assemblies are arranged in planes perpendicular to the longitudinal direction and spaced apart, allowing them to be compactly integrated without expanding the motor's external dimensions significantly.

Inventive Principle:

Principle #7Nested doll (Nesting)

3Object-affected harmful factors

If coupling spring assemblies are used to reduce vibrations, then vibration cancellation improves, but the device complexity increases

Engineering Contradiction:

Improvevibration cancellationVSAvoidmotor structure complexity

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The coupling spring assemblies are strategically positioned at specific locations within the motor structure, arranged in planes perpendicular to the longitudinal direction and spaced apart. This localized placement optimizes vibration cancellation at critical points without requiring complex mechanisms throughout the entire motor, thereby reducing overall device complexity while maintaining effective vibration cancellation.

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 design significantly reduces residual vibrations, enhances the motor's ability to provide higher driving forces, and allows for more efficient conversion of linear oscillations into desired movements, such as oscillatory rotations, while maintaining a compact form factor.

Implementation Method 1

a stator comprising a coil for driving the armature into oscillatory motion

Methodology Applied

Scientific EffectElectromagnetic force: Lorentz Force

Implementation Method 2

the armature is at one end biased with a coil spring against the casing, the amplitude control spindle is biased at one end by a coil spring against the casing

Methodology Applied

Scientific EffectElasticity: Elasticity

Implementation Method 3

The coupling unit includes at least two coupling spring assemblies and at least a coupling element

Methodology Applied

Scientific EffectElasticity: Elasticity

Data Source

PatentUS10587177B2Linear motor and electric device with linear motor

Publication Date: 2020.03.10 BRAUN GMBH

AI summary

A linear motor includes an armature mounted for driven linear oscillation substantially along a longitudinal direction; a secondary mass mounted for linear oscillation substantially along the longitudinal direction; and a coupling unit for coupling the armature and the secondary mass. The coupling unit includes at least two coupling spring assemblies and at least a coupling element, the coupling spring assemblies being arranged in planes perpendicular to the longitudinal direction and being spaced apart from each other, and the coupling element being fixedly connected with the coupling spring assemblies.