Oblique Counter-Pivot Stone for Clockwork Rate Stability
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Solution Overview
Problem
Mechanical watches experience rate variations due to differences in the behavior of the balance pivot when in contact with the counter-pivot stone, particularly in horizontal positions, caused by varying forces from the hairspring and pivot play in the stone orifice.
Innovation Solution
A pivoting guidance device for clockwork shafts featuring a pierced stone and a counter-pivot stone with an oblique bearing surface, allowing for adjustable cant and yaw angles to stabilize the pivot's behavior across horizontal positions, thereby equalizing the rate variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the counter-pivot stone is parallel to the pierced stone in a classic assembly, then the structure is simple and easy to manufacture, but the pivot has unstable behavior in horizontal positions due to play in the orifice and varying hairspring forces
Solution Approach 1:
The counter-pivot stone is oriented at an angle relative to the pierced stone, creating an asymmetric configuration. This angular orientation of the counter-pivot plane stabilizes the pivot in horizontal positions by eliminating play and equalizing friction across different watch positions, thereby resolving the technical contradiction between pivot stability and structural simplicity.
2Measurement precision
If the pivot plays in the orifice of the stone, then the assembly is easy to manufacture with clearance fits, but the rate varies between horizontal positions due to different hairspring forces
Solution Approach 1:
The invention changes the orientation parameter of the counter-pivot stone, introducing a specific angular relationship between the counter-pivot plane and reference directions. This parameter change stabilizes the pivot behavior and equalizes rate across positions while maintaining manufacturable clearance fits, resolving the contradiction between precision and ease of manufacture.
3Reliability
If the pivot contacts the counter-pivot stone in horizontal positions, then the bearing function is activated, but friction varies and causes rate deviations
Solution Approach 1:
By orienting the counter-pivot stone at an angle rather than parallel to the pierced stone, the invention creates an asymmetric contact geometry. This asymmetric orientation equalizes the friction forces experienced by the pivot in different horizontal positions, eliminating rate deviations while maintaining reliable bearing function.
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 device stabilizes the pivot's behavior in horizontal positions, minimizing friction and maintaining necessary lubrication, resulting in reduced rate deviations between positions, thus enhancing chronometric accuracy.
Implementation Method 1
the normal to the plane tangent common to the pivot and to the first bearing surface is oblique with respect to the axis according to a cant angle
Implementation Method 2
the pivot has an unstable behavior in the horizontal positions, which is due to its pivoting on the horizontal counter-pivot stone
Implementation Method 3
The essential functions of the counter-pivots are, on the one hand, the reduction of friction at the level of the pivot
Data Source
Figure 1~17
Figure 3~4
Figure 5~6
AI summary
The apparatus (10) has a perforated block (3) secured in a stone support (7), through which a pivot pin (2) of the shaft (1) is secured, and a cover block (4) indirectly fixed to a circuit board (6) of a clockwork (100) by the stone support. The cover block has a first support surface (5) cooperating in abutment with distal end of the pivot pin. The normal (N) to the common tangential plane (PT) of pivot pin and axis (D) together form a deck level (PCP) which has a first angular orientation at a yaw angle (alpha ) with respect to reference direction (DR) of the circuit board.