Magnet Coupling Torque Transmission for Quiet Power Tools

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Solution Overview

Problem

Existing electric power tools produce noise due to mechanical torque transmission, particularly mechanical rotary impact tools which generate significant impact noise during operation, necessitating the development of a quieter tool that maintains impact torque.

Innovation Solution

An electric power tool employing a magnet coupling with a driving magnet member and a driven magnet member, where the moment of inertia of the driven magnet member is larger, and a clutch mechanism to transmit torque contactlessly and manage synchronization loss for intermittent rotary impact force generation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If a mechanical torque transmission structure is used, then torque transmission is achieved, but noise is generated

Engineering Contradiction:

ImprovenoiseVSAvoidtorque transmission

Core Design Contradiction:

Object-affected harmful factorsVSReliability

Solution Approach 1:

The patent replaces the mechanical contact-based torque transmission system with a magnetic coupling system. The magnetic coupling transmits torque from the motor to the output shaft through magnetic fields without physical contact, thereby eliminating mechanical friction and impact noises while maintaining reliable torque transmission capability.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces a magnetic field as an intermediary between the motor and output shaft for torque transmission. The magnetic coupling acts as a mediator that transfers rotational force without direct mechanical contact, reducing noise generation from mechanical impacts and friction.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Force

If a hammer strikes the anvil in mechanical rotary impact tool, then impact torque is generated, but large impact noise is produced

Engineering Contradiction:

Improveimpact torqueVSAvoidimpact noise

Core Design Contradiction:

ForceVSObject-generated harmful factors

Solution Approach 1:

The patent replaces the mechanical hammer-anvil impact system with a magnetic coupling system that generates rotary impact forces through magnetic field interactions. The driven magnet member with larger moment of inertia creates impact torque when synchronizing with the driving magnet member, eliminating the need for physical hammer strikes and their associated noise.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent employs periodic synchronization and desynchronization of the magnetic coupling to generate intermittent rotary impact forces. The driven magnet member periodically catches up to and synchronizes with the driving magnet member, creating rhythmic impact torque without continuous mechanical striking.

Inventive Principle:

Principle #19Periodic action

3Object-affected harmful factors

If magnet coupling is used for contactless torque transmission, then noise is reduced, but moment of inertia balance must be optimized

Engineering Contradiction:

ImprovenoiseVSAvoidmoment of inertia design

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The patent optimizes the moment of inertia parameters of the magnetic coupling system, specifically designing the driven magnet member to have a larger moment of inertia than the driving magnet member. This parameter optimization enables the system to generate effective impact torque while maintaining smooth operation and reducing noise.

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 solution effectively reduces noise while maintaining torque transmission, enabling the electric power tool to operate quietly with enhanced torque transmission efficiency through magnetically transmitting torque and utilizing synchronization loss to generate intermittent rotary impacts.

Implementation Method 1

a magnet coupling including a driving magnet member coupled to the driving shaft side and a driven magnet member coupled to the output shaft side

Methodology Applied

Scientific EffectMagnetic coupling: Magnetism

Implementation Method 2

a clutch mechanism provided between the motor and the torque transmission mechanism

Methodology Applied

Scientific EffectFriction: Friction

Data Source

PatentUS12151354B2Electric power tool

Publication Date: 2024.11.26 PANASONIC INTELLECTUAL PROPERTY MANAGEMENT CO LTD

AI summary

A torque transmission mechanism includes a magnet coupling including a driving magnet member coupled to a side of driving shaft driven into rotation by a motor and a driven magnet member coupled to a side of an output shaft on which a front-end tool is attachable. A clutch mechanism is provided between the motor and the torque transmission mechanism. A moment of inertia on the side of the driven magnet member is larger than a moment of inertia on the side of the driving magnet member.