Magnetic Timepiece Gear Layout for Higher Torque Stability
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Solution Overview
Problem
Magnetic gears face limitations in maximum mechanical torque transfer due to parasitic magnetic torque and modulation of magnetic torque, leading to inefficiencies and increased power consumption, as well as variations in torque transmission during wheel rotation.
Innovation Solution
Incorporating a third wheel with permanent magnetic poles and optimizing the angle and phase shift between the first and third wheels allows for increased mechanical torque transfer without slippage, balancing magnetic radial forces and compensating for parasitic torque, thereby enhancing torque stability and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If wheels with larger tooth diameters are used to increase maximum mechanical torque, then the maximum transferable mechanical torque increases, but the spacing between adjacent teeth increases making magnetic coupling less effective
Solution Approach 1:
The patent transitions from a single-plane magnetic gear to a three-dimensional configuration with wheels arranged at different angular positions around a central axis. This spatial arrangement allows magnetic flux to couple teeth across larger physical distances by utilizing the radial dimension, effectively resolving the contradiction between larger tooth diameters and effective magnetic coupling spacing.
Solution Approach 2:
The patent introduces a magnetic circuit including a magnetizable ring or bridge structure that acts as an intermediary to transfer magnetic flux between teeth of wheels separated by larger distances. This intermediary maintains effective magnetic coupling even when direct tooth-to-tooth spacing is increased, allowing larger wheel diameters without losing coupling efficiency.
2Power
If the distance between two wheels is minimized to increase magnetic coupling, then torque transfer efficiency improves, but manufacturing tolerances become extremely difficult to control
Solution Approach 1:
The magnetizable ring or bridge structure serves as a mechanical intermediary that physically maintains the optimal spacing between wheels while providing a magnetic pathway. This intermediary component absorbs spacing variations, allowing larger manufacturing tolerances without compromising torque transfer efficiency, as the magnetic circuit is established through the intermediary rather than direct wheel-to-wheel coupling.
Solution Approach 2:
The patent changes the magnetic coupling parameter from direct air-gap dependence to intermediary-mediated flux paths. By introducing magnetizable materials with high permeability as intermediaries, the system becomes less sensitive to spacing parameter variations, effectively decoupling torque transfer efficiency from precise wheel positioning tolerances.
3Force
If a third wheel is added to increase maximum torque transfer, then mechanical torque capacity increases, but device complexity increases
Solution Approach 1:
The third wheel in the patent serves multiple functions simultaneously: it provides additional magnetic coupling paths for torque transfer, acts as a structural element to balance radial forces on the central axis, and enables the magnetizable ring to function as an effective magnetic intermediary. This multi-functionality justifies the added complexity by achieving torque multiplication without proportionally increasing system complexity.
Solution Approach 2:
The third wheel acts as a counterbalancing element that offsets radial magnetic forces acting on the other wheels. By strategically positioning the third wheel and its magnetic poles, the system achieves force balance that reduces bearing loads and improves overall stability, making the increased torque capacity sustainable without disproportionate complexity increases.
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 significantly increases the maximum mechanical torque that can be transferred in the magnetic gear, reducing parasitic torque and maintaining stability, with the ability to transmit greater mechanical torque using lower motor torque, and achieving more than double the torque of traditional magnetic gears with only two wheels.
Implementation Method 1
the first magnetic toothing has a first magnetic coupling with the second magnetic toothing generated by the first magnetic fluxes which momentarily polarise in magnetic attraction, teeth of the second magnetic toothing, which are momentarily located in a first magnetic coupling zone with the first magnetic toothing
Implementation Method 2
the second wheel is provided with teeth made of a soft ferromagnetic material defining a second magnetic toothing
Implementation Method 3
first magnetic fluxes which momentarily polarise in magnetic attraction, teeth of the second magnetic toothing, which are momentarily located in a first magnetic coupling zone
Data Source
AI summary
A mechanism (1) including a magnetic gear (2) including a first wheel (6A) and a second wheel (6B), the first wheel (6A) being provided with first permanent magnetic poles (7) forming first magnetic toothing (8), the second wheel (6B) being provided with a second magnetic toothing (10) made of a ferromagnetic material, the first wheel (6A) and the second wheel (6B) being arranged such that the first magnetic toothing has a first magnetic coupling with the second magnetic toothing (10). The gear (2) has a third wheel (6C) having second permanent magnetic poles (9) which form a third magnetic toothing (12), the third wheel and the second wheel being arranged such that the third magnetic toothing has a second magnetic coupling with the second magnetic toothing; the magnetic gear (2) being arranged such that the first and third wheels are each angularly positioned in a specific manner.