Timepiece Barrel Assembly with Reduced Bung Diameter
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Solution Overview
Problem
Conventional clockwork barrel architectures face limitations in reducing the diameter of the barrel arbor and bung while ensuring sufficient power reserve and fatigue strength, making it challenging to increase the power reserve by increasing the number of spring turns without risking breakage.
Innovation Solution
The solution involves alternative barrel architectures that include a multiphase cobalt-nickel-chromium alloy spring with specific composition and a bung with a reduced diameter, featuring protruding zones, a split plug design, and adjustable washers to facilitate machining and assembly, allowing for a lower bung diameter and improved axial displacement control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If the diameter of the barrel arbor and bung is reduced to increase power reserve, then the space available for the spring increases, but the risk of breakage increases due to insufficient material section
Solution Approach 1:
The patent applies composite materials by combining a cobalt-nickel-chromium alloy for the mainspring with a steel or stainless steel bung. This material selection optimizes both the elastic properties of the spring and the mechanical strength of the bung, allowing reduced dimensions while maintaining fatigue strength and preventing breakage.
Solution Approach 2:
The patent changes the geometric parameters by reducing the bung diameter to less than 9 times the spring thickness (below the conventional 10-20 ratio), while compensating for the reduced material section through optimized material properties and precise dimensional control to maintain sufficient fatigue strength.
2Volume of stationary object
If the bung diameter is reduced below 9 times the spring thickness, then more space is available for the spring, but the structural integrity and fatigue strength are compromised
Solution Approach 1:
The patent optimizes geometric parameters by setting the bung radius to less than 9 times the spring thickness, balancing space utilization with structural integrity. This precise parameter control ensures sufficient material section for fatigue strength while maximizing the available space for spring storage.
Solution Approach 2:
The use of steel or stainless steel for the bung provides the necessary mechanical strength and fatigue resistance to compensate for the reduced dimensions, ensuring reliability is maintained despite the compact design.
3Strength
If conventional barrel architecture with axial screw and square is used, then the assembly is structurally sound, but the minimum diameter of pivot bearing increases
Solution Approach 1:
The patent extracts and eliminates the conventional axial screw and square components from the barrel arbor design. By removing these traditional elements, the patent achieves a reduced pivot bearing diameter while maintaining structural integrity through alternative design approaches.
Solution Approach 2:
The patent segments the functional requirements by separating the ratchet mounting function from the pivot bearing function, allowing independent optimization of each component's dimensions and reducing the overall size requirements.
Data Source
Figure 1A~6C
Figure 1~15c
Figure 7~10
AI summary
The invention relates to a timepiece barrel assembly (1) comprising a barrel mainspring (2) mounted between a barrel drum (3) and a surface (5) for receiving a barrel core coaxial to said drum (3). Said spring (2) is made from a multiphase cobalt/nickel/chrome alloy having a Young's modulus of between 200 and 240 GPa and a shear modulus of between 80 and 100 GPa, and having a width/thickness ratio of between 9 and 21, and the maximum radius of said core (4), which is made of steel, relative to the swivel axis thereof (D), is less than nine times the maximum thickness of said spring (2), and said barrel assembly (1) comprises, at said spring (2) or said drum (3), a means (6) for limiting the longitudinal play between said drum (3) and said mainspring (2) in the direction of said swivel axis (D).