Balance Spring Shifting Pinning Point for Easy Mounting
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Solution Overview
Problem
Existing balance springs with two hairsprings connected by a raised terminal curve device face challenges in mounting due to the proximity of the free end to the balance staff, making assembly difficult.
Innovation Solution
A balance spring design with a shifting device in the inner coil of the second hairspring, allowing the free end to be pinned to a stud between its coils without touching, using a rigid extension piece and adjustable stud positioning system to prevent elastic torque and facilitate assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the balance spring uses a conventional two-hairspring design with raised terminal curve device, then good isochronism is achieved, but the free end is too close to the balance staff making mounting difficult
Solution Approach 1:
The invention introduces a third dimension by adding height to the pinning point through the extension piece. The free end is elevated above the plane of the second hairspring, allowing it to be pinned to the stud without the coils touching the staff during operation. This vertical displacement resolves the spatial conflict between maintaining good isochronism and enabling easy mounting.
2Ease of operation
If the free end is pinned close to the balance staff to improve mounting, then assembly becomes easier, but the coils may touch the staff during development phases
Solution Approach 1:
The extension piece acts as an intermediary element between the second hairspring and the pinning point. It transfers the connection to the stud while maintaining spatial separation, ensuring that the coils remain clear of the staff during both contraction and expansion phases. This mediator structure enables both easy assembly and reliable operational clearance.
Data Source
AI summary
A balance spring including a first hairspring, the inner coil of which includes a collet arranged to be mounted on a staff, and a second hairspring connected to the outer coil of the first hairspring by a raised terminal curve device. The inner coil of the second hairspring includes a device for shifting the pinning point including a free end arranged to be pinned up to a stud in the plane of the second hairspring.