Spring Mechanism for Electromagnetic Drive Tuning
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Solution Overview
Problem
Electric toothbrushes with electromagnetic drives face challenges in converting linear oscillation into desired rotational motion, leading to undesirable vibrations and noise, especially when the frequency approaches the resonant frequency of the drive shaft and workpiece.
Innovation Solution
A spring mechanism that includes a housing, a movable spring connected to the housing, a drive shaft with a magnet, and an adjustable tuning element connecting the drive shaft to the spring, allowing for the conversion and tuning of the workpiece movement to achieve desired rotational motion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the electromagnet frequency approaches the resonant frequency of the drive shaft and workpiece, then the workpiece movement amplitude increases, but undesirable vibrations and noise increase dramatically
Solution Approach 1:
The spring mechanism acts as an intermediary element between the electromagnet and the drive shaft. It decouples the direct connection, allowing the system to achieve desired workpiece movement while filtering out harmful vibrations and noise through the spring's elastic properties and tuned resonance characteristics.
Solution Approach 2:
The spring mechanism changes the dynamic parameters of the system by introducing elastic compliance. This modifies the frequency response characteristics, allowing the system to operate at resonant frequencies for maximum amplitude while the spring's damping properties control the harmful vibrations and noise.
2Shape
If linear oscillation from the electromagnet is converted into rotational motion, then desired workpiece motion is achieved, but vibrations and noise increase
Solution Approach 1:
The spring mechanism serves as a mediator in the motion conversion process. It allows the linear oscillation from the electromagnet to be transformed into rotational motion of the drive shaft while the spring's elastic properties smooth out the transition, reducing vibrations and noise that would otherwise be generated by direct mechanical coupling.
3Ease of manufacture
If replacement heads include the permanent magnet, drive shaft and workpiece, then assembly is simplified, but tuning of workpiece movement becomes difficult
Solution Approach 1:
The spring mechanism introduces dynamic adjustability to the replacement head assembly. By making the spring's mechanical properties (such as pre-compression or attachment points) adjustable, the system maintains simplified assembly while enabling tuning of the workpiece movement characteristics to match different operating conditions.
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 spring mechanism efficiently translates the electromagnetic movement into controlled workpiece motion, reducing vibrations and noise, enabling simple and effective tuning of the workpiece's frequency and amplitude, thereby enhancing the user experience.
Implementation Method 1
a spring mechanism that includes a housing, a spring connected to the housing, wherein at least a portion of the spring is movable with respect to the housing
Implementation Method 2
A movable permanent magnet (or a pair of permanent magnets) is positioned proximate to the electromagnet, such that the permanent magnet is driven to oscillate at an oscillating frequency by the electromagnet
Data Source
AI summary
A spring mechanism for an electromagnetic drive unit converts or translates the movement and/or actuation of the electromagnet into a desired movement of the workpiece and enables simple and efficient tuning of the workpiece movement. The spring mechanism includes a housing, a spring connected to the housing, wherein at least two sections of the spring are movable with respect to the housing, a drive shaft that includes a first end having a magnet and a second end for attachment to a workpiece, and at least two tuning elements connecting the drive shaft to the movable portion of the spring. At least one of the tuning elements is adjustable. In one embodiment, the spring may be a flat spring, and the movable sections may each be positioned between a pair of cutouts defined in the spring.