Spiral Spring With Segmented Leaves For Isochronism
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Solution Overview
Problem
Traditional spiral springs in mechanical watches suffer from suboptimal isochronism due to uneven reaction forces on the balance-staff, making precise alignment and force control challenging, especially when two spirals are used in opposite directions.
Innovation Solution
A spiral spring design featuring two identical leaves wound in the same plane and direction, connected by a circularly symmetrical frame that minimizes reaction forces on the balance-staff, allowing for improved isochronism and easier implementation, potentially made from silicon or diamond materials using deep etching techniques.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a traditional single spiral spring is used, then the structure is simple, but the isochronism is suboptimal due to uneven reaction forces on the balance-staff
Solution Approach 1:
The spiral spring is divided into two identical leaves (10a, 10b) that are wound in the same plane and direction. These leaves are arranged at 180° relative to each other and connected by a rigid frame (14) at their outer ends. This segmentation allows the reaction forces from each leaf to offset each other, minimizing the net reaction force on the balance-staff pivots and improving isochronism.
2Reliability
If two traditional spirals are used in opposite directions, then the forces can be balanced, but the alignment and force control become difficult due to manufacturing variations
Solution Approach 1:
Instead of using two separate traditional spirals that need to be aligned, the invention merges two identical leaves (10a, 10b) into a single integrated structure connected by a rigid frame (14). This merging ensures that both leaves have identical characteristics and are precisely aligned by construction, eliminating the alignment and force control difficulties associated with assembling two separate spirals.
Solution Approach 2:
The invention uses two leaves wound in the same direction (rather than opposite directions) and arranged at 180° to each other. This asymmetric arrangement combined with identical characteristics allows the leaves to exert equal and opposite forces on the balance-staff, achieving force balance while simplifying manufacturing compared to traditional opposite-direction spirals.
3Volume of moving object
If the spiral center moves during development, then the spiral can be compact, but reaction forces are generated at the balance-staff pivots that degrade isochronism
Solution Approach 1:
The two leaves (10a, 10b) are arranged at 180° to each other and exert equal and opposite forces on the balance-staff. This counterbalancing arrangement ensures that the reaction forces from each leaf offset each other, minimizing the net reaction force on the pivots and improving isochronism while maintaining a compact spiral structure.
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 enhances isochronism by offsetting forces and reducing reactions on the balance-staff, allowing for more precise timekeeping while maintaining simplicity in construction and material choice.
Implementation Method 1
a spiral spring (10) comprising several leaves (10a, 10b) wound into one another in the shape of a spiral of Archimedes
Implementation Method 2
particularly silicon-based spirals, in particular made from monocrystalline silicon, potentially covered by a layer of silica, but also spirals made from diamond, obtained by growth then deep etching
Data Source
AI summary
A spiral spring (10) for the movement of a watch, includes a plurality of coplanar leaves (10a, 10b) wound into one another. Furthermore, the inner ends of each leaf are rigidly connected to a single collet (12). The leaves (10a, 10b) and the collar (12) are produced as a single part.