Balance Wheel Return Rake With Dual Elastic Blades
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Solution Overview
Problem
Existing escapement systems in portable horology, such as wristwatches, face challenges with spiral springs due to their delicate manufacture, variability in vertical position, and energy loss through friction and torsion, which affect precision and size compatibility.
Innovation Solution
A return member comprising a rake with a toothed sector and two independent elastic blades, which pivot between extreme positions, compensates for friction and maintains symmetry, allowing energy storage and release without simultaneous deformation, thus enabling a balanced angular motion and reducing size constraints.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a spiral spring is used as a return member, then the balance wheel can be returned to its initial position, but the system suffers from variability in vertical position and energy loss through friction and torsion
Solution Approach 1:
The return member is divided into two independent elastic blades instead of using a single spiral spring. Each blade operates independently to return the rake to its initial position, reducing the complexity and energy loss associated with the traditional spiral spring mechanism.
Solution Approach 2:
The invention extracts and eliminates the spiral spring from the escapement system. By removing the spiral spring entirely and replacing it with a different return mechanism (two elastic blades acting on a rake), the patent eliminates the problems of variability in vertical position and energy loss through torsion that are inherent to spiral springs.
2Reliability
If a spiral spring is used as a return member, then the balance wheel can be returned to its initial position, but the manufacture becomes very delicate and complex
Solution Approach 1:
The return member is segmented into two separate elastic blades that are simpler to manufacture than a spiral spring. Each blade is a straightforward elastic element that can be easily produced and assembled, eliminating the delicate manufacture requirements of the spiral spring.
Solution Approach 2:
The spiral spring is extracted and removed from the system. The replacement mechanism using a rake and two elastic blades presents a much simpler manufacturing challenge, as these components can be produced using standard machining techniques without the delicate assembly required for spiral springs.
3Use of energy by moving object
If two elastic blades are used to press the rake towards its rest position, then energy storage and release is improved, but the structure becomes more complex
Solution Approach 1:
The two elastic blades are merged into a single rake component that acts on the balance wheel pinion. By combining the function of two blades into one integrated rake structure, the patent achieves energy storage and release while minimizing structural complexity. The rake serves as the common element that both blades act upon, unifying the return mechanism.
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 provides a more robust and efficient balance wheel return mechanism that maintains precision and starts easily, overcoming the limitations of spiral springs by minimizing friction and size constraints, ensuring consistent operation in both directions.
Implementation Method 1
the elastic blade must be capable of storing energy when it is deformed by the motion of the rake. It must then return this energy to move the rake in the opposite direction
Data Source
AI summary
A return member for a balance wheel of a timepiece, replacing a spiral spring. This return member includes a rake provided with a toothed sector arranged to work together with a balance wheel pinion. The rake has an axis of rotation allowing it to move between two extreme positions, called working positions, separated by a rest position. The return member also has two springs arranged to press the rake towards its rest position. Each spring is made up of an elastic blade arranged to store energy, then to return it to the rake. Each elastic blade works alternately so that they never work simultaneously. The return member may be in an escapement, a clockwork movement or a timepiece comprising such a movement.