Coplanar Blade Mainspring Barrel for Watch Movement
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Solution Overview
Problem
Conventional barrel designs in mechanical watchmaking, which use multiple ball bearings for improved pivoting, suffer from inefficiency, alignment issues, and increased bulk and cost, while alternative solutions like cantilevered mounting with rollers or spiral springs face size and assembly challenges.
Innovation Solution
A barrel spring comprising coplanar blades spirally wound one inside the other, with independent or connected blades, and a torque limiting system, allowing for reduced size and improved pivoting efficiency without the need for ball bearings, using materials like monocrystalline silicon or polycrystalline diamond for optimal elasticity and shaping.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple ball bearings are used for pivoting the drum, then pivoting quality is improved, but device complexity and alignment difficulty increase
Solution Approach 1:
The patent merges the pivoting function with the spring attachment function by fixing the spring directly to the barrel arbor hook, eliminating the need for separate ball bearings. The spring itself serves as both the power storage element and the pivoting mechanism, reducing component count while maintaining functional reliability.
Solution Approach 2:
The patent extracts and eliminates the ball bearing components from the barrel assembly, replacing them with a direct spring-to-arbor connection. This removes the alignment complexity and reduces the number of precision components required while maintaining the essential pivoting capability.
2Reliability
If multiple ball bearings are used for pivoting the drum, then pivoting quality is improved, but manufacturing cost increases
Solution Approach 1:
By combining the spring attachment and pivoting functions into a single integrated mechanism, the patent reduces the number of components that need to be manufactured and assembled. This eliminates the cost of multiple ball bearings and their precision alignment, simplifying manufacturing while maintaining performance.
Solution Approach 2:
The patent replaces expensive precision ball bearings with a simpler, more cost-effective spring attachment mechanism. The spring-to-arbor connection uses standard watchmaking components that are cheaper to manufacture and assemble, reducing overall production costs while maintaining adequate pivoting quality.
3Reliability
If cantilevered mounting with rollers is used, then pivoting quality is improved, but device bulk increases
Solution Approach 1:
The patent merges the spring, arbor, and pivoting mechanism into a compact integrated assembly. The spring is fixed directly to the arbor hook, eliminating the need for separate rollers and cantilevered mounting structures, thereby reducing the overall barrel volume while maintaining functional performance.
4Volume of moving object
If coplanar blades are wound one inside the other, then space utilization is improved, but stress concentration increases
Solution Approach 1:
The patent applies different properties to different parts of the spring system. The blades are made from materials with high elasticity and fatigue resistance (such as phosphor bronze or silicon) to handle the stress concentrations. The cross-sectional geometry and thickness distribution are optimized locally to distribute stresses evenly while maintaining compact winding.
Solution Approach 2:
The patent employs composite material structures for the spring blades, combining materials with complementary properties. For example, using phosphor bronze or silicon-based alloys that provide both the necessary elasticity for compact winding and the strength to withstand repeated stress cycles without fatigue failure.
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 enhances pivoting efficiency and power reserve by minimizing friction and size, while simplifying assembly and reducing costs, maintaining the number of turns and adapting gear ratios for optimal torque delivery.
Implementation Method 1
a barrel spring comprising a plurality of coplanar blades spirally wound one inside the other
Implementation Method 2
cooperate with the interior of the barrel drum in order to limit the winding torque of the barrel
Data Source
AI summary
To improve the pivoting and efficiency of a mainspring barrel, the invention relates to a mainspring barrel for a watch movement, characterized in that it comprises a plurality of coplanar blades (10a, 10b) spirally wound one inside the other, in that the inner ends of each blade are each attached to a fastening device (12) for being fixed to a mainspring barrel arbor, in that the outer ends of each blade are arranged substantially symmetrically with respect to the center of the spiral and are arranged so as to cooperate with a mainspring barrel. The invention also relates to a mainspring barrel containing such a spring.