Clockwork Torque Joint Geometry for Low-Stress Alignment
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Solution Overview
Problem
Existing clockwork mechanisms using square joints for torque transmission in watchmaking suffer from high risk of breakage due to concentrated stress, inaccuracy, and wear, especially when using fragile materials and require multiple quarter turns for alignment, which is detrimental to torque transmission and component integrity.
Innovation Solution
A clockwork mechanism with male and female elements featuring a cross-sectional design with hollows and protrusions that allow for increased torque transmission and reduced contact pressure, enabling the use of fragile materials and precise alignment without sharp edges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a square joint is used to transmit torque between components, then the structure is simple and easy to manufacture, but the stress is concentrated at the interface leading to high risk of breakage
Solution Approach 1:
The patent replaces the square joint with a circular cross-section joint where the male element has a circular profile and the female element has a corresponding circular groove. This curvature eliminates the sharp corners of the square joint that cause stress concentration, distributing the stress more evenly across the interface and preventing breakage while maintaining manufacturing simplicity.
2Device complexity
If a square joint is used to transmit torque, then the structure is simple, but the contact pressure at the interface is significant preventing use of fragile materials
Solution Approach 1:
The circular cross-section design replaces the square geometry, creating a continuous curved surface contact instead of edge-to-surface contact. This curvature distributes the contact pressure evenly across the entire interface area, significantly reducing peak stresses and enabling the use of fragile materials like silicon or ceramic that cannot withstand the concentrated pressures of square joints.
3Device complexity
If a square joint is used to transmit torque, then the structure is simple, but there is significant play leading to significant inaccuracies
Solution Approach 1:
The circular cross-section joint eliminates the gaps and play inherent in square joints by providing continuous surface contact. The curved surfaces naturally self-align and maintain constant contact during rotation, eliminating the positional inaccuracies and play that occur with square geometries while keeping the structure simple.
4Device complexity
If a square male element is used, then the structure is simple, but quarter turns are required to index the female element causing additional wear
Solution Approach 1:
The circular cross-section design eliminates the need for quarter-turn indexing required by square elements. The continuous circular geometry allows smooth rotation and engagement without discrete positioning steps, preventing the repeated impact and misalignment wear that occurs during quarter-turn indexing operations.
Data Source
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AI summary
The present invention proposes a clockwork mechanism comprising at least two components and a device for driving one of said components in rotation by the other, comprising a male element (1a) carried by one of said components and a female element (2a) carried by the other of said components (2) and arranged to cooperate with said male element (1a). The male element (1a) has, in cross-section, a shape defining overall an outer circle of outer diameter D and center C and comprising at least one hollow or flat area (6), symmetrical with respect to an axis passing through the center C of the outer circle and directed towards the center C so as to be tangent to an inner inscribed circle of center C and inscribed diameter d such that the difference between the outer diameter D and the inscribed diameter d is greater than or equal to 8% and less than 20% of the outer diameter D.The female element (2a) has, in cross-section, the same shape as the male element (1a), arranged to receive and cooperate with said male element (1a) in order to transmit a couple from one to the other of said organs. The cross-sectional shape of the male element (1a) comprises at least two hollows or flats (6) arranged around the inner inscribed circle (10) to form between them a protuberance (12) connecting them to each other, said protuberance (12) having an apex (12a) coinciding with an arc of the outer circle (4).