Horological Friction System Spring Washer Torque Control
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Solution Overview
Problem
Existing friction systems in horological movements face issues with unpredictable friction torque adjustment, sensitivity to assembly/disassembly, and difficulty in manufacturing repeatability, particularly in connecting members like the cannon-pinion and arbor, which are sensitive to high torque and require precise clamping force control.
Innovation Solution
A friction system comprising a staff with a spring washer having catches that form a kinematic link between stationary elements, allowing precise adjustment of friction torque through deformation of the spring between the stationary elements, ensuring high torque transmission and easy manufacturing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If manual indenting is used to adjust friction, then the friction torque can be set, but the adjustment is unpredictable and lacks precision
Solution Approach 1:
The invention changes the physical state of the spring from a relaxed state to a compressed state by applying a compression force. This compression deformations the spring, which then exerts a consistent elastic force that provides predictable and precise friction torque. The parameter change from uncompressed to compressed state enables controlled and reproducible friction adjustment.
Solution Approach 2:
The spring is pre-compressed during assembly to a specific degree, creating a predetermined elastic force before the watch is put into operation. This preliminary compression action ensures that the friction torque is already set to the correct value, eliminating the need for manual adjustment and ensuring consistency across all units.
2Reliability
If manual indenting is used to connect cannon-pinion to arbor, then friction is obtained, but the connection is sensitive to assembly and disassembly
Solution Approach 1:
The spring provides a dynamic connection that automatically adapts to assembly and disassembly operations. The elastic nature of the spring allows it to compress and expand, maintaining consistent friction torque throughout the operational lifecycle. This dynamic behavior makes the connection more robust compared to rigid manual indenting.
Solution Approach 2:
The spring acts as a cushioning element that absorbs variations in assembly force and maintains stable friction torque. By pre-compressing the spring, the system creates a buffer that compensates for minor assembly variations, ensuring consistent performance without being sensitive to how the components are assembled or disassembled.
3Force
If conventional friction systems are used, then friction torque can be transmitted, but high torque transmission capability is limited
Solution Approach 1:
The spring can be compressed to different degrees to adjust the friction torque level. By changing the compression parameter, the system can accommodate various torque transmission requirements while maintaining reliable friction. The elastic force of the compressed spring provides consistent torque transmission capability.
Solution Approach 2:
The spring's curved, elastic structure allows it to deform and return, providing a more durable friction connection compared to flat or rigid elements. This curved geometry enables the spring to absorb stress and maintain consistent friction torque under high torque transmission conditions.
4Manufacturing precision
If metal foils are used to obtain friction, then friction is achieved, but manufacturing repeatability is difficult to guarantee
Solution Approach 1:
The spring's elastic properties provide a natural parameter that can be consistently controlled through compression. By standardizing the compression force and degree of deformation during assembly, the system achieves high manufacturing repeatability and batch consistency. The elastic force is more predictable than the friction from metal foils.
Solution Approach 2:
The spring automatically provides the necessary friction force through its elastic deformation, eliminating the need for complex adjustment mechanisms. The spring self-regulates the friction torque based on its compression state, making the manufacturing process simpler and more repeatable across batches.
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 system enables precise and reproducible friction torque adjustment, withstands high torque, and simplifies assembly, providing consistent performance across batches.
Implementation Method 1
a spring (5) mounted on the staff (1) and arranged between the second stationary element (4) and the third stationary element (6), the spring (5) taking the form of a washer comprising an inner part (51) close to the staff (1) bearing against the third stationary element (6), and an outer, peripheral part bearing resiliently against an annular element of the second stationary element (4), the spring (5) being resiliently deformed and forming a kinematic link both between the first stationary element (2) and the toothed member (3), and between the second stationary element (4) and the toothed member (3) up to a predefined friction torque
Implementation Method 2
the washer comprises at least two catches (50) disposed at its outer periphery, the catches (50) being arranged to resiliently bear against the annular element of the second stationary element (4)
Data Source
AI summary
A friction system for a horological movement includes a staff; a first stationary element mounted on the staff; a second stationary element mounted on the staff; a toothed member mounted to rotate freely on the staff between the first stationary element and the second stationary element; a third stationary element mounted on the staff; a spring mounted on the staff and arranged between the second stationary element and the third stationary element. The spring takes the form of a washer including an inner part close to the staff bearing against the third stationary element, and an outer, peripheral part of the washer bearing resiliently against an annular element of the second stationary element, the spring being resiliently deformed and forming a kinematic link both between the first stationary element and the toothed member, and between the second stationary element and the toothed member up to a predefined friction torque.