Chronograph Coupling System Friction Transmission Backlash Elimination
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Solution Overview
Problem
Chronograph coupling systems face issues such as trembling of the seconds hand due to backlash and the risk of unwanted jumping, which existing solutions either require complex structures or are difficult to control during production, and do not effectively address the problem of trembling.
Innovation Solution
A coupling system that uses friction wheels to transmit rotation between the intermediate and output wheels, with safety teeth to prevent trembling and minimize jumps, and an elastic element to control the contact force and limit movement, allowing for integration into standard movements with minimal modification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If toothed wheels are used for coupling, then the structure is simple and easy to manufacture, but backlash causes trembling of the seconds hand
Solution Approach 1:
A friction wheel is introduced as an intermediary element between the intermediate wheel and the output wheel. The friction wheel receives rotational motion from the intermediate wheel through friction contact and transmits it to the output wheel, eliminating the backlash inherent in direct toothed wheel engagement while maintaining a relatively simple structure
Solution Approach 2:
The patent replaces the traditional toothed wheel meshing mechanism with a friction-based rotational transmission system. Instead of relying on mechanical interlocking of teeth, the system uses friction contact to transmit rotation, thereby eliminating backlash and trembling while preserving ease of manufacture
2Reliability
If friction disks are used for vertical coupling, then backlash is eliminated, but the mechanism requires great height space
Solution Approach 1:
The patent transitions from a vertical coupling arrangement (requiring height space) to a horizontal coupling arrangement within the plane of the movement. The friction wheel is positioned horizontally between the intermediate wheel and output wheel, eliminating the need for vertical stacking of friction disks and reducing the height requirement while maintaining backlash elimination
3Volume of moving object
If toothed coupling is used, then the structure is compact, but unwanted jumps occur due to tooth contact
Solution Approach 1:
The friction wheel serves as a mediator that decouples the direct toothed wheel interaction. By transmitting rotation through friction contact rather than direct tooth engagement, the system maintains the compactness of the toothed wheel structure while preventing unwanted jumps caused by tooth summit-to-flank contact
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 system eliminates trembling and minimizes unwanted jumps of the chronograph seconds hand, ensuring smooth operation and compatibility with standard clock movements by using friction wheels and safety teeth to absorb imperfections and control the kinematic connection.
Implementation Method 1
a first friction wheel (17) constrained to rotate with said intermediate wheel (9) and a second friction wheel (19) constrained to rotate with a second wheel chosen from said input wheel (3) and said output wheel (5)... adapted to transmit rotation between said intermediate wheel (9) and said second wheel
Implementation Method 2
said lever (11) being subjected to a return force by means of an elastic element (21)
Data Source
AI summary
A coupling system for a chronograph mechanism is presented. The system can include an input wheel intended to be driven by a drive member; an output wheel intended to drive at least one display member; an intermediate wheel continuously kinematically connected to the input wheel or the output wheel, where the intermediate wheel changes between a coupled state where the input wheel is kinematically connected to the output wheel and an uncoupled state where the kinematic connection is broken. The system also includes a first friction wheel constrained to rotate with the intermediate wheel and a second friction wheel constrained to rotate with either the input wheel and the output wheel; a first safety wheel constrained to rotate with said intermediate wheel that includes a first set of safety teeth; and a second safety wheel constrained to rotate with the second wheel that includes a second set of safety teeth.