Clock Movement Friction Assembly With Elastic Tabs for Precise Torque
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Solution Overview
Problem
Conventional friction systems in watch movements are unpredictable, difficult to adjust precisely, sensitive to assembly/disassembly, and cannot withstand high torque, with manufacturing repeatability issues and complex implementations.
Innovation Solution
A friction system comprising a shaft with a first and second fixed element, a toothed member, and elastic tabs that deform elastically to create a kinematic link, allowing precise and repeatable adjustment of friction torque by controlling the displacement of the second fixed element on the shaft.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If manual adjustment of lantern pin friction is used, then the system is simple to manufacture, but the friction torque precision and repeatability are poor
Solution Approach 1:
The patent changes the friction mechanism from manual pinching to elastic deformation of tabs. The friction torque is controlled by adjusting the axial position of the second fixed element, which changes the deformation parameter of the elastic tabs. This allows precise control of friction torque through parameter adjustment rather than manual skill-based assembly.
Solution Approach 2:
The elastic tabs automatically adjust and maintain the friction torque through their elastic deformation. The system self-regulates the friction force based on the axial displacement of the second fixed element, eliminating the need for manual adjustment and skill-based assembly of traditional lantern pins.
2Strength
If conventional lantern pin friction is used, then the structure is simple, but the system cannot withstand high torque and is sensitive to assembly/disassembly
Solution Approach 1:
The patent uses conical bearing surfaces on the elastic tabs and corresponding conical surfaces on the toothed member and fixed elements. This conical geometry distributes the torque load across the elastic deformation of multiple tabs rather than concentrating it on a single lantern pin, increasing torque capacity and reducing sensitivity to assembly variations.
3Manufacturing precision
If spiral-shaped friction spring is used, then friction torque can be achieved, but the system becomes complex and occupies significant space
Solution Approach 1:
The patent divides the friction mechanism into multiple discrete elastic tabs arranged around the toothed member, rather than using a single large spiral spring. This segmentation allows the friction function to be distributed across multiple small components, reducing the overall radial footprint while maintaining friction torque control capability.
Solution Approach 2:
The patent transitions from a planar spiral spring design to a three-dimensional arrangement where elastic tabs extend axially from the second fixed element. This dimensional change allows the friction mechanism to utilize axial space rather than radial space, minimizing the radial footprint while maintaining effective friction torque control.
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
Enables precise, repeatable, and high-torque transmission with a minimized footprint, facilitating integration into watch movements and compensating for manufacturing tolerances.
Implementation Method 1
said elastic tabs being in elastic contact with said second bearing surface of the sleeve, said elastic tabs being arranged to deform elastically under stress from the second bearing surface
Data Source
Figure 1~5
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Figure 8~9
AI summary
The invention relates to a friction system (100) for a clock movement comprising: a shaft (1), with longitudinal axis (L), a first fixed element (2), mounted rotationally fixed on the shaft (1); said first fixed element (2) having a first bearing surface (40); a second fixed element (7) mounted rotationally fixed on the shaft (1); a toothed member (3), mounted freely in rotation on the shaft (1) between the first fixed element (2) and the second fixed element (7);characterized in that the toothed member (3) is integral with a sleeve (4) having a second bearing surface (42), and in that the second fixed element (7) comprises a body (72) configured to be rotationally integral with the shaft (1) and elastic tabs (71), projecting from the body (72) extending in the direction of the toothed member (3), said elastic tabs (71) being in elastic contact with said second bearing surface (42) of the sleeve (4), said elastic tabs (71) being arranged to deform elastically under stress from the second bearing surface (42) and to form a kinematic connection both between the first fixed element (2) and the toothed member (3) and between the second fixed element (7) and the sleeve (4) integral with the toothed member (3) up to a predetermined friction torque.