Chronograph Lever Device Eliminates Return Spring Wear
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Solution Overview
Problem
Conventional chronograph mechanisms experience significant wear and require high pressure to operate due to the torque induced by return springs, leading to reliability issues and discomfort in use, particularly in chronographs with vertical or lateral clutches.
Innovation Solution
A lever device with a main lever that pivots between two stable positions, eliminating the need for a return spring by using beaks to interact with the column wheel, reducing wear and pressure required for actuation, and incorporating a secondary lever to manage the clutch shoe's engagement and disengagement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a return spring is used to maintain the clamp in its closed position, then the chronograph can be started and stopped, but significant torque is induced causing wear to the mechanism
Solution Approach 1:
The patent removes the return spring from the mechanism entirely. Instead of using a spring to maintain the clamp in its closed position, the invention uses a system where the beak can rest on column flanks without spring pressure, eliminating the source of harmful torque and wear while preserving chronograph operation.
Solution Approach 2:
Instead of using a spring to actively push the clamp closed, the invention inverts the approach by allowing gravity and mechanical geometry to passively maintain positions. The beak rests on column flanks in angular positions between columns, and the clamp remains open without active spring force, reversing the conventional spring-driven approach.
2Ease of operation
If a return spring is used to maintain the clamp in its closed position, then the chronograph can be controlled, but relatively high pressure must be exerted on the push-button
Solution Approach 1:
By removing the return spring, the patent eliminates the opposing spring force that required high push-button pressure to overcome. The clamp can now be actuated without fighting against spring pressure, significantly reducing the force needed on the push-button while maintaining full chronograph control functionality.
3Reliability
If elastic blade deformation means are used to open the clamp, then the chronograph can be started, but the elastic properties may deteriorate over time modifying clamp positioning
Solution Approach 1:
The patent removes the elastic blade deformation mechanism entirely. Instead of relying on elastic properties that deteriorate over time, the invention uses a rigid mechanical system where the beak interacts with column flanks and the clamp is positioned by mechanical constraints rather than elastic deformation, eliminating the source of positioning drift.
Solution Approach 2:
The mechanism uses the column wheel and beak geometry themselves to provide the positioning and actuation functions, rather than relying on separate elastic elements. The columns and beak form a self-contained mechanical system that maintains accuracy without degrading elastic properties.
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 solution minimizes wear on device parts, reduces the force needed for actuation, enhances long-term reliability, and improves user comfort by eliminating the need for high pressure on the push-button, while maintaining mechanical locking of start-stop functions.
Implementation Method 1
a main lever (20) mounted so as to pivot, about a first pivot axis, alternately between two stable positions
Implementation Method 2
an anchor provided with two beaks which, in each of the two stable positions, are alternately located, one between two columns and the other in contact with a peripheral flank of another column
Data Source
AI summary
The present invention relates to a lever device (10) of a watch mechanism, comprising a column wheel (16) and a main lever (20) mounted so as to pivot, about a first pivot axis (24), alternately between two stable positions. The main lever (20) comprises an anchor provided with two beaks (21a, 21b) which, in each of the two stable positions, are alternately located, one of them between two columns (17) and the other in contact with a peripheral flank of another column (17). The main lever (20) further comprises a distal part (26, 29) for controlling the watch mechanism. The anchor and the distal part (26, 29) of the lever are arranged to pivot about the first pivot axis (24). The invention also relates to a watch movement comprising a chronograph and the lever device arranged to bring the chronograph from a disengaged configuration to an engaged configuration and vice versa.