Wobble Drive Mechanism for Oscillating Power Tools
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Solution Overview
Problem
Eccentric drives in oscillating tools are limited by stroke length, susceptible to vibrations, and require reinforced housings under heavy loads, leading to reduced tool performance and increased costs.
Innovation Solution
A wobble drive mechanism that converts rotational motion into oscillating motion using a wobble shaft and wobble member, reducing vibrations and allowing for increased stroke length without housing size increases, by internalizing mechanism loads and minimizing bearing loads on the housing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If an eccentric drive mechanism is used to generate oscillating motion, then the tool can achieve cutting functionality, but the stroke length is limited and vibrations increase
Solution Approach 1:
The patent replaces the traditional eccentric mechanical drive system with a magnetic field-based oscillating mechanism. Magnets mounted on the oscillating member interact with stationary magnets to generate oscillating motion through magnetic attraction and repulsion, eliminating the need for eccentric bearings, drive pins, and complex mechanical linkages. This substitution reduces mechanical vibrations and allows for longer stroke lengths without increasing housing size.
Solution Approach 2:
The patent changes the fundamental operating parameters of the oscillating mechanism by using magnetic field strength and polarity reversal to control motion, rather than relying on mechanical eccentricity ratios and bearing clearances. This allows for adjustable stroke lengths and oscillation frequencies independent of housing dimensions, resolving the contradiction between stroke length and vibration generation.
2Length of moving object
If the housing is reinforced to handle heavy cutting loads, then stroke length is maintained, but tool cost increases
Solution Approach 1:
By replacing the mechanical eccentric drive with a magnetic oscillating system, the patent eliminates the need for reinforced housings to withstand heavy mechanical loads. The magnetic interaction forces are contained within the oscillating member assembly, allowing standard housing designs to suffice while maintaining full stroke length under heavy cutting loads, thereby reducing manufacturing costs.
3Length of moving object
If the housing size is increased to accommodate a longer stroke mechanism, then stroke length increases, but tool dimensions increase
Solution Approach 1:
The magnetic oscillating mechanism generates extended stroke lengths within a compact footprint by utilizing magnetic field interactions rather than mechanical linkages. The oscillating member with mounted magnets can achieve longer travel distances without requiring proportionally larger housing dimensions, as the magnetic forces act directly across the oscillation path without needing extended mechanical lever arms or eccentrics.
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 wobble drive mechanism enhances tool robustness, reduces vibrations, and maintains stroke length under heavy loads, increasing tool life and efficiency with longer blades, while minimizing tool length and reducing the need for reinforced housings.
Implementation Method 1
Rotation of the drive shaft causes the wobble shaft to wobble about an axis of the drive shaft. The tool driver holds the wobble member against the rotation of the wobble shaft such that the wobble member wobbles without rotating which results in an oscillating motion of the drive axis of the wobble member
Data Source
AI summary
An oscillating drive for a power tool includes a wobble shaft located on a drive shaft of a motor for a power tool, and a wobble member rotatably supported on the wobble shaft. The wobble member includes a wobble drive structure that defines a drive axis. A tool driver includes a tool drive structure at one end that is coupled to the wobble drive structure and a tool holder configured to releasably retain an accessory tool. Rotation of the drive shaft causes the wobble shaft to wobble about an axis of the drive shaft. The tool driver holds the wobble member against the rotation of the wobble shaft such that the wobble member wobbles without rotating which results in an oscillating motion of the drive axis of the wobble member in a plane that is parallel to the axis of the drive shaft. The oscillating motion of the drive axis causes the tool driver to oscillate.