Linear Actuator for Watch Balance Spring Stiffness Control
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Solution Overview
Problem
Existing mechanical watch mechanisms face challenges in regulating the balance spring's stiffness and rate due to complexity, space constraints, and the risk of chronometric errors from clamping the balance spring.
Innovation Solution
A simplified actuation system for regulating members in mechanical watches, featuring an inertial mass, a balance spring with adjustable stiffness, and a linearly displacing actuator that applies variable force or torque to the flexible element, allowing independent regulation of the rate and beat without increasing the movement's thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the balance spring is clamped to the index key to eliminate play, then the chronometric stability improves, but the balance spring is stressed and off-centred windings are created causing chronometric errors
Solution Approach 1:
A dedicated clamping device with a clamping lever and clamping stud is introduced as an intermediary mechanism between the balance spring and the index key. This separate clamping system applies force through a controlled mechanical action rather than direct attachment, eliminating play while maintaining proper alignment and avoiding off-centring of the balance spring windings.
2Ease of operation
If the index key is moved to regulate the rate after clamping the balance spring, then the rate can be fine-tuned, but the index key cannot be moved once the balance spring is clamped
Solution Approach 1:
The regulation function is divided into two independent segments: rate regulation through index key movement and beat regulation through clamping device adjustment. This segmentation allows the index key to be moved for rate tuning without being constrained by the clamping state, as the clamping device separately controls the balance spring fixation while the index key independently adjusts the effective length of the balance spring.
3Measurement precision
If a complex index system with movable parts is used to adjust the force on the flexible element, then the rate regulation precision improves, but the movement thickness increases
Solution Approach 1:
The complex movable parts mechanism is extracted and replaced with a simplified clamping device that achieves precise force adjustment through a direct mechanical linkage. The clamping lever with its specific geometry provides sufficient regulation precision without requiring multiple movable components, thereby reducing the overall thickness of the movement while maintaining the ability to precisely control the force applied to the flexible element.
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 compact, efficient actuation system that allows precise regulation of the watch's rate and beat, reducing the risk of chronometric errors and accommodating smaller watch movements.
Implementation Method 1
the actuator being configured to perform a substantially linear, preferably rectilinear, displacement, in order to actuate the prestressing means
Implementation Method 2
a balance spring which comprises a wound ribbon
Implementation Method 3
the energy required to rotate the hands is stored in a barrel and then delivered by a sprung balance system
Implementation Method 4
comprising an inertial mass, for example a balance
Data Source
AI summary
A regulating member (1) for a horological movement, including an inertial mass, for example a balance (23), a balance spring (25) including a wound ribbon (2) and an adjustor for adjusting the stiffness of the balance spring provided with a flexible element (5) arranged in series with the wound ribbon (2), the adjustor including a prestressing device (6) for applying a variable force or torque to the flexible element (5) in order to adjust the rate of the regulating member (1), the regulating member (1) including a system for actuating the prestressing device (6), the actuation system including an actuator (30) mechanically connected to the prestressing device (6), the actuator (30) being configured to perform, at least in part, a substantially linear, preferably rectilinear, displacement, in order to actuate the prestressing device.