Timepiece Case Bayonet Friction Torque Assembly
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Solution Overview
Problem
Conventional closing/opening systems for timepiece cases lack sufficient tightening/loosening torque to securely assemble/disassemble the back and middle parts, with existing gaskets providing only 0.7 N·m torque, which is insufficient for secure assembly/disassembly, especially limited by assembly tolerances.
Innovation Solution
A closing/opening system for timepiece cases incorporating a bayonet connection and a device creating a friction torque, featuring a tightening element and a resiliently compressible element, such as an O-ring, that generates a constant friction torque during the assembly/disassembly process, enhancing the secure tightening/loosening torque between the parts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a conventional gasket is used in the closing/opening system, then the case can be assembled and disassembled, but the tightening torque is insufficient (only 0.7 N·m) to securely secure the back with the middle part
Solution Approach 1:
The patent introduces a tightening element with specific geometric parameters (diameter, width, position) that can be adjusted to optimize the friction torque. By changing the parameters of the tightening element, such as its diameter and position relative to the rotation axis, the friction torque can be increased from the conventional 0.7 N·m to the required 3 N·m or more, thereby securely securing the back with the middle part while maintaining assembly reliability
Solution Approach 2:
The patent employs a composite structure combining a resiliently compressible element (gasket) with a tightening element. The gasket provides sealing and initial compression, while the tightening element (made of friction material or with high friction coefficient surface) provides the additional friction torque needed for secure assembly. This composite approach allows both sealing and high torque requirements to be met simultaneously
2Reliability
If the tightening torque is increased to secure assembly, then the assembly becomes more reliable, but the torque is limited by the assembly tolerances of the gasket in the middle part
Solution Approach 1:
The tightening element acts as an intermediary between the gasket and the case parts. It transfers and amplifies the friction torque while being less sensitive to gasket assembly tolerances. The tightening element's larger diameter and strategic positioning allow it to generate sufficient friction torque (3 N·m or more) even when gasket assembly tolerances vary, thereby decoupling the torque generation from the precision requirements of the gasket installation
Solution Approach 2:
The patent moves the friction torque generation from the gasket interface (conventional approach) to a dedicated tightening element with larger radius from the rotation axis. By increasing the moment arm (distance from rotation axis), the same friction force generates higher torque. This dimensional change allows achieving high torque (3 N·m) without requiring extremely tight gasket assembly tolerances
3Ease of operation
If a bayonet connection device is used for assembling/disassembling, then the mechanical connection is established, but the friction torque provided by the gasket alone is insufficient to secure the connection
Solution Approach 1:
The patent merges two functions into a single tightening element: (1) providing friction torque for secure assembly, and (2) guiding the bayonet connection operation. The tightening element is positioned and dimensioned to engage with the case parts in a way that generates friction torque throughout the rotation path, complementing the bayonet connection's mechanical engagement. This combination ensures both ease of operation and sufficient securing force
Solution Approach 2:
The tightening element is designed to engage and begin generating friction torque before the bayonet connection is fully seated. As the back is rotated onto the middle part, the tightening element makes contact first and establishes the frictional grip, preparing the connection for secure locking. This preliminary action ensures that the friction torque is already present when the mechanical connection is completed, securing the assembly immediately
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 achieves a constant, secure tightening/loosening torque of up to 3 N·m, ensuring reliable assembly/disassembly of the case parts over their entire course of travel, improving the security and service life of the timepiece by maintaining a consistent frictional force throughout the process.
Implementation Method 1
a device for creating a friction torque between these first and second parts, the device for creating a friction torque including tightening faces configured to cooperate with one another when closing/opening the case
Implementation Method 2
a resiliently compressible element comprised in the same tightening face as the tightening element, said resiliently compressible element being intended to be compressed between these first and second parts
Data Source
AI summary
A closing/opening system for a case of a timepiece is defined particularly in first and second parts of the case. The system includes a device for producing a mechanical connection, particularly a bayonet connection between these first and second parts and a device for creating a friction torque between these first and second parts. The device for creating a friction torque includes tightening faces to cooperate with one another when closing/opening the case and which are defined in the first and second parts. The system further includes a tightening element in one of these two tightening faces. The tightening element generates a constant friction torque during a course of travel of one of the two parts relative to the other when closing/opening the case of the timepiece.