Watch Push-Crown Cage Eliminates Spring Scraping Wear
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Solution Overview
Problem
The existing push-crown mechanisms in timepieces experience premature wear due to scraping and friction between the return spring and rotating components, which limits the continuous driving of the crown.
Innovation Solution
A spring is arranged within a cage that rotates with the push-crown, eliminating relative movement between the spring and rotating components, and featuring faces that match the bearing surfaces to ensure normal friction and continuous operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the return spring is positioned around the stem of the crown in conventional push-crowns, then the spring can provide return force, but relative movement between the spring and rotating components causes scraping and premature wear
Solution Approach 1:
A cage is introduced as an intermediary component between the return spring and the rotating push-crown components. The cage rotates with the push-crown while the spring rotates with the cage, eliminating direct relative movement between the spring and rotating components. This mediator structure prevents scraping and friction while maintaining the spring's return force function.
Solution Approach 2:
The cage combines multiple functions: it serves as a mounting structure for the spring, a rotating component synchronized with the push-crown, and a friction-reducing interface with bearing surfaces. By merging these functions into a single component, the design eliminates the need for separate guides or supports that would cause relative movement and wear.
2Ease of operation
If a washer promoting sliding is inserted at each end of the spring, then sliding is favored, but friction still prevents continuous driving of the crown
Solution Approach 1:
The cage acts as an intermediary that rotates synchronously with the push-crown, eliminating relative movement between the spring and rotating components. The bearing surfaces of the cage provide a controlled friction interface that is sufficient to drive the ring gear continuously without the sliding friction limitations of washers.
Solution Approach 2:
The design changes the friction parameter from sliding friction (washers) to rolling/friction contact through the bearing surfaces of the cage. This parameter change allows for continuous driving while maintaining adequate friction for gear engagement without the harmful effects of washer-based sliding mechanisms.
3Reliability
If the spring is fixed relative to rotating components, then continuous driving is enabled, but relative movement causes scraping and wear
Solution Approach 1:
The cage serves as a mediator that rotates with both the push-crown and the spring, creating a reference frame where no relative movement occurs between the spring and rotating components. This eliminates scraping effects while maintaining the necessary friction at the bearing surfaces for continuous operation.
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
This arrangement extends the life of the spring and ensures continuous driving of the ring gear by minimizing friction and preventing scraping, thereby enhancing the durability and functionality of the push-crown mechanism.
Implementation Method 1
the relative movement between the spring and the rotating components of the pusher-crown causes a scraping phenomenon and thereby premature wear of the spring
Implementation Method 2
the cage having faces of a shape similar to that of the faces on which it bears, normal friction is present in the bearing zone, which makes it possible to guarantee continuous driving of the ring gear
Data Source
Figure 1~2
Figure 3~4a
Figure 4b~4c
AI summary
The present invention relates to a push-button crown (3) comprising: - a tube (6) fixed to a watch case (1), - a hollow head (4) integral with a rod (7) movable relative to the tube (6) and defining an axis (7a), said hollow head (4) being mounted to move in rotation and translation respectively around and along the axis (7a) of the rod (7), - a return spring (10) disposed around the rod (7), the push-button crown (3) being characterized in that it comprises a cage (11) housing the spring (10), said cage (11) being traversed by the rod (7) and comprising an upper part (12) integral with the hollow head (4) and a lower part (13) mounted freely relative to the hollow head (4),said upper part (12) cooperating with the lower part (13) so as to be able to drive the lower part (13) in its rotational movement and so as to be able to move in translation along the axis (7a) relative to said lower part (13), said spring (10) being mounted in compression within the cage (11) so as to be driven in rotation with said cage (11).