Sinuous Return Spring for Watch Repositioning
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Solution Overview
Problem
The existing repositioning devices for watch mechanisms require high force to return the hammer to its rest position, leading to increased user effort and energy consumption, while reducing spring stiffness to alleviate this also compromises the repositioning function and may cause mechanical wear.
Innovation Solution
A specially shaped return spring with a sinuous design, optimized using topological optimization techniques, provides a substantially constant elastic restoring moment over a range of angular positions, reducing the force required to return the hammer to its rest position while maintaining sufficient force for repositioning the cam.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the stiffness of the return spring is reduced to decrease the moment of force required to return the hammer to its rest position, then the user effort is reduced, but the force available for repositioning the cam is insufficient, causing mechanical wear or malfunction
Solution Approach 1:
The return spring is designed with variable stiffness characteristics through its sinuous geometry. The spring exhibits different stiffness values at different deformation stages: lower stiffness during the repositioning phase to minimize user effort, and higher stiffness during the return phase to ensure reliable hammer return. This dynamic stiffness adjustment resolves the contradiction between ease of operation and reliability.
Solution Approach 2:
The patent changes the geometric parameters of the return spring, specifically采用 a sinuous design with optimized curvature and dimensions. This geometric parameter change allows the spring to provide variable force characteristics throughout its deformation range, enabling low user effort during cam repositioning while maintaining sufficient return force.
2Reliability
If the stiffness of the return spring is increased to ensure sufficient force for repositioning the cam, then the repositioning function is reliable, but the moment of force required to return the hammer to its rest position increases, leading to high energy consumption
Solution Approach 1:
The return spring dynamically adjusts its stiffness based on the operational phase. During the repositioning phase, the spring operates in a low-stiffness regime to minimize energy input from the user. During the return phase, the spring exhibits higher stiffness to reliably return the hammer. This dynamic behavior reduces overall energy consumption while maintaining repositioning reliability.
Solution Approach 2:
The sinuous geometry of the return spring creates non-linear force-deformation characteristics. By optimizing the curvature and dimensional parameters, the spring provides low force during cam repositioning (reducing energy consumption) while maintaining sufficient force for reliable hammer return, thus resolving the contradiction between reliability and energy consumption.
3Device complexity
If a traditional spring design is used with constant stiffness, then the structure is simple, but the force required to return the hammer varies significantly, causing high user effort during the return phase
Solution Approach 1:
The return spring transitions from a static constant-stiffness design to a dynamic variable-stiffness design through its sinuous geometry. The spring naturally provides different stiffness values at different deformation stages, reducing user effort during the return phase without significantly complicating the overall structure. This dynamic characteristic resolves the contradiction between structural simplicity and ease of operation.
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 reduces the moment of force needed to return the hammer to its rest position, enhancing user convenience and reducing energy consumption while preventing mechanical wear, by maintaining a stable repositioning function.
Implementation Method 1
the force of the return spring in such a repositioning device increases proportionally to its deformation
Implementation Method 2
a return spring (6) acting on the hammer (4)
Data Source
Figure 1~2
Figure 3
Figure 4
AI summary
The present invention relates to a repositioning device (1) for watchmaking, comprising a repositioning cam (7), a hammer (4), a return spring (6), and a control device (3). The control device (3) is arranged to hold the hammer (4) in a rest position against the action of the return spring (6), release the hammer (4) so that it strikes the repositioning cam (7) under the action of the return spring (6) and rotates it until it is locked in a predetermined position, and return the hammer (4) to its rest position against the action of the return spring (6). The return spring (6) is arranged to operate within a predetermined range of winding angles during each return of the hammer (4) to its rest position. The return spring (6) is a nonlinear spring whose stiffness is zero or negative in at least a portion of the predetermined range.