Watch Crown Spring Washer With Spherical Cap for Wear Reduction
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Solution Overview
Problem
Screw-down crowns in watches experience wear and contamination due to the friction of the spring's last strand against the crown surface, leading to potential mechanical failure and contamination.
Innovation Solution
A screw-in crown design featuring a subassembly with a spring mechanism, a support washer, and a cap with a spherical cap bearing on a bearing surface, which compresses a sealing gasket for a watertight seal, reducing wear and enhancing reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a helical spring is used in the crown mechanism, then the spring provides the necessary elastic force for the screwing action, but the friction of the last strand of the spring on the crown surface causes wear and contamination
Solution Approach 1:
A spherical cap is introduced as an intermediary element between the spring and the crown body. The spring acts on the spherical cap instead of directly on the crown body, eliminating the harmful friction of the spring's last strand on the crown surface. The spherical cap transfers the elastic force while preventing wear and contamination of the crown mechanism.
Solution Approach 2:
The invention employs a spherical cap geometry to replace the traditional flat or threaded contact surface. This spherical shape allows for smooth rolling contact and reduces friction between the spring and the crown body, thereby minimizing wear and preventing contamination of the internal mechanism.
2Reliability
If the crown is screwed down tightly to improve water resistance, then the seal is enhanced, but the friction and wear on the spring and crown mechanism increase
Solution Approach 1:
The spherical cap serves as a mediator that decouples the sealing function from the friction-generating contact. By allowing the spring to act on the spherical cap rather than directly on the crown threads, the design enables tight sealing while minimizing wear on the screwing mechanism.
Solution Approach 2:
The spherical cap's curved surface reduces contact friction during the screwing operation, allowing the crown to be tightened securely for water resistance without generating excessive wear on the spring and crown threads.
3Device complexity
If the spring bears directly on the crown body, then the structure is simpler, but wear particles contaminate the crown mechanism and watch
Solution Approach 1:
The spherical cap is introduced as a simple intermediary component that prevents wear particles from contaminating the crown mechanism. This addition minimizes wear by eliminating direct contact between the spring's last strand and the crown body, while the spherical geometry facilitates smooth motion.
Solution Approach 2:
By replacing direct contact with spherical cap contact, the design reduces friction and wear particle generation. The spherical shape allows for smoother operation and prevents the spring's last strand from rubbing against the crown body, thereby avoiding contamination.
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 design provides a more reliable and watertight seal, minimizing wear and contamination, thereby improving the watch's water resistance and mechanical integrity.
Implementation Method 1
at least one spring mechanism with at least one spring mounted in compression in a chamber and extending in said axial direction
Implementation Method 2
this spherical cap 99 is arranged to bear on a bearing surface 290 which comprises a constituent of the subassembly 20
Implementation Method 3
compress a sealing gasket for a watertight seal
Data Source
Figure 1
Figure 2~5
AI summary
Screwed crown (100) for a watch case (110) (200) with a through housing (90), comprising a tube (5) axially insertable into this housing (90) and a subassembly (20) with a crown body (1) manipulable by a user, axially movable relative to the tube (5) and comprising a spring mechanism with a spring (4) mounted in axial compression in a chamber (32), which subassembly (20) comprises, bearing on a distal end of the spring (4) on a first side, a support washer (9) comprising on a second side opposite to the first side an axially centered spherical cap (99), which spherical cap (99) is arranged to bear on a bearing surface (290) comprising a constituent of the subassembly (20).