Watch Barrel Profile System with Alternating Arcs for Wear Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional self-winding timepiece barrels experience premature wear and damage due to the abrasive friction between the mainspring and the drum's inner side wall, particularly at sharp angles formed by notches, leading to reduced service life and potential malfunctions.
Innovation Solution
A barrel design featuring a drum with an internal side wall profiled using alternating arcs of sliding and friction circles, which reduces wear by eliminating sharp edges and allowing the mainspring to slide smoothly when tension exceeds a threshold, using a geometric arrangement that centers arcs of friction between tangent points, thus minimizing abrasive contact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If notches are introduced in the inner side wall of the drum to increase maximum driving torque, then the power reserve is significantly improved, but the wear of the barrel components accelerates due to sharp angles at the notch edges
Solution Approach 1:
The patent replaces the conventional notched profile with alternating arcs of sliding and friction circles. The sliding arcs provide smooth curved surfaces that eliminate sharp angles, while the friction arcs provide controlled friction zones. This curvature-based design maintains the ability to achieve high driving torques through friction modulation without creating stress concentration points that would accelerate wear.
Solution Approach 2:
The patent applies different local properties to different zones of the inner side wall: sliding arcs provide low-friction surfaces for smooth passage, while friction arcs provide controlled friction for torque regulation. This spatial variation in surface properties allows the system to achieve high maximum torques in friction zones without subjecting the entire structure to abrasive wear conditions.
2Power
If the friction coupling between mainspring and drum wall is increased to achieve higher driving torque, then the power reserve is improved, but the abrasive wear accelerates due to fine particles generated during sliding
Solution Approach 1:
The curved arc profiles eliminate sharp edges and corners where stress concentration and particle generation would be most severe. The smooth transitions between sliding and friction zones reduce impact forces and minimize the generation of abrasive fine particles during the sliding process.
Solution Approach 2:
The alternating pattern of sliding and friction arcs creates a periodic sequence of low-friction and controlled-friction zones. As the mainspring unwinds, it periodically passes through sliding arcs that clear debris and reduce particle generation, followed by friction arcs that provide necessary torque control. This periodic alternation prevents continuous abrasive contact.
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
This design significantly reduces wear and tear on the barrel components, enhancing the longevity and reliability of the timepiece by smoothing the frictional interaction between the mainspring and the drum, preventing rapid degradation and malfunctions.
Implementation Method 1
the outer coil cooperates by friction with said inner side wall of the drum and is free to slide against the arcs of friction of said wall in the event that the tension of the spring exceeds a value of given slip threshold
Data Source
Figure 1A
Figure 1B
Figure 1C~1D
AI summary
The invention relates to a barrel (11) for an automatic watch comprising a drum (4) with an inner side wall (3) and a barrel spring (1) provided with an outer coil (2) which frictionally engages with the inner side wall (3) of the drum (4), the profile of the inner side wall (3) comprising a plurality of alternately arranged sliding arcs of circle (5) and friction arcs of circle (6), wherein the sliding and friction arcs (5, 6) substantially correspond to a geometric arrangement consisting of a profile construction element (7) acting as a geometric reference for determining the positions and dimensions of sliding arcs (5) and friction arcs (6).