Mainspring Barrel Torque Control via Winding Turn Limiting
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Solution Overview
Problem
Self-winding watches lack a guaranteed minimum torque level at the end of their power reserve, leading to accuracy issues and potential disruptions in functions requiring drive energy, as the torque of the mainspring decreases with winding turns.
Innovation Solution
A barrel with a device that limits the number of winding turns, decoupling it from the number of barrel rotations, maintaining a consistent torque level by using a slip bridle for the mainspring tension and incorporating a positioning ring with abutment surfaces and a return spring to restrict rotations, ensuring a constant torque for accurate timekeeping and reliable function activation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If the barrel is allowed to rotate freely without limiting the number of winding turns, then the power reserve is extended, but the torque decreases towards the end leading to accuracy deterioration and potential disruption of functions
Solution Approach 1:
The invention segments the relationship between barrel rotations and mainspring windings by introducing a decoupling mechanism. The barrel can rotate multiple times (extending power reserve) while the mainspring is wound a limited number of times (maintaining torque consistency). This is achieved through the interaction of the positioning ring with abutment surfaces that allow the barrel to overshoot and rotate back, creating a segmented motion pattern that separates the two rotational counts.
2Reliability
If locking devices are used to limit the number of barrel rotations, then the number of winding turns is fixed, but the torque varies during the winding process and the device complexity increases
Solution Approach 1:
The positioning ring with abutment surfaces provides a self-regulating mechanism that automatically limits the number of mainspring windings while allowing the barrel to rotate freely. The system uses the interaction between the positioning ring's abutment surfaces and the barrel's protrusions to create automatic engagement and disengagement points, eliminating the need for complex external locking devices. The mechanism serves itself by using the existing rotational motion to trigger the torque limitation.
3Force
If the mainspring is attached with a hook for manual winding, then the torque is maintained, but the number of winding turns is not limited leading to over-winding issues
Solution Approach 1:
The positioning ring with abutment surfaces creates a feedback mechanism that provides tactile and mechanical feedback to the user during winding. As the barrel rotates and the positioning ring engages with the abutment surfaces, the user receives feedback about the number of windings completed. This feedback system allows the user to control the winding process without complex electronic or mechanical counting devices, maintaining ease of operation while preventing over-winding.
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 solution maintains a consistent torque level, improving watch accuracy and reliability by separating decreasing mainspring windings from the drive mechanism, allowing safe activation of additional functions even at the end of the power reserve.
Implementation Method 1
a return spring (15) which is trained on the barrel (1) and has a free end which forms a protruding part and cooperates with the first pin (9), for pushing the positioning ring (5) in the direction of arrow a
Implementation Method 2
the mainsprings of self-winding movements have a so-called slip bridle at their outer end, which allows the mainspring to slide on the inner wall of the barrel drum when a certain torque is exceeded
Data Source
Figure 1A~1B
Figure 2
Figure 3A~4B
AI summary
The present invention relates to a mainspring barrel (1) for a clockwork mechanism. The mainspring barrel (1) has a device (10) for limiting the number of unwinding revolutions of the mainspring barrel (1), wherein this device (10) still allows the number of winding revolutions of the mainspring barrel (1) to be unlimited.