Sealed Watch Crown Geometry for Deep-Dive Watertight Sealing
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Solution Overview
Problem
Existing watch cases, including those with control mechanisms, fail to maintain a watertight seal during dives to great depths due to insufficient sealing gaskets and pressure resistance, as described in prior art designs.
Innovation Solution
A crown stem design with an annular contact surface inclined at a defined angle less than 90° to a longitudinal central axis, combined with complementary annular receiving surfaces on the case, and the use of toroidal sealing gaskets, ensures a watertight seal by closing gaps under high water pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If simple gaskets are used in traditional watch cases, then the device complexity is reduced, but the reliability of watertight seal under high water pressure deteriorates
Solution Approach 1:
The patent employs a toroidal sealing gasket with a specific curved cross-section that fits into a corresponding grooved recess. The curved geometry of the gasket allows it to deform and conform to the grooved surface, creating an effective seal under water pressure. This curvature-based sealing mechanism replaces complex multi-component sealing systems while maintaining reliability under diving conditions.
Solution Approach 2:
The invention changes the geometric parameters of the sealing interface by using inclined annular contact surfaces on the crown stem that meet the case at specific angles. This angular parameter change allows the sealing surfaces to self-align and maintain contact under pressure, improving seal reliability without increasing overall device complexity.
2Ease of manufacture
If threaded holes are used to secure the case back, then the ease of manufacture is improved, but the reliability of the seal under high water pressure deteriorates due to potential damage to the threaded hole
Solution Approach 1:
The patent extracts the sealing function from the threaded connection area by providing a separate grooved recess in the case that receives a toroidal sealing gasket. This separates the mechanical fastening function (threaded hole) from the sealing function (grooved recess with gasket), allowing the threaded hole to be used for assembly while the dedicated grooved recess provides reliable sealing under water pressure without being compromised by threading operations.
3Adaptability or versatility
If a control mechanism is mounted through the case middle, then the adaptability of the watch is improved, but the reliability of the watertight seal deteriorates due to additional sealing requirements
Solution Approach 1:
The patent applies local quality by providing specific sealing features at the control mechanism location: inclined annular contact surfaces on the crown stem and a corresponding grooved recess in the case middle. These localized sealing structures are positioned exactly where the control mechanism penetrates the case, providing enhanced sealing at this critical location without affecting other parts of the case. The inclined surfaces and grooved recess create a localized seal that maintains watertight integrity while allowing the control mechanism to function.
Data Source
Figure 1
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Figure 2b
AI summary
The stem-crown (9) of a water-resistant watch case (1) comprises a stem (11) inserted into a tubular opening (12) in a case middle (2) of the watch case, and a crown (13) comprising a first portion connected to the stem and a second manipulator portion. The first portion of the crown includes an annular contact surface (21) inclined at a defined angle less than 90° to a longitudinal central axis of the stem-crown, extending from the connection of the stem to the first portion of the crown outwards from the second portion of the crown. In a rest position, the first portion of the crown contacts or rests against an annular receiving surface (22) of the case middle, which is complementary in shape to one end of the tubular opening facing outwards.