Escapement Mechanism Cam Surface Staggering
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Solution Overview
Problem
Conventional watch escapement mechanisms have geometry that is not optimized for both clearance and impulse functions, leading to increased friction, wear, and energy losses, which affects the efficiency and reliability of the mechanism over time.
Innovation Solution
The escapement mechanism features a fork and peg assembly with distinct cam surfaces and engagement surfaces on two levels, allowing for optimized geometric profiles for clearance and impulse functions, minimizing friction and enabling a rolling movement without slipping, and allowing for different reduction ratios for each function to reduce torque take-up during disengagement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional identical geometry is used for both release and impulse functions, then manufacturing is simplified, but friction and wear increase due to non-optimized contact surfaces
Solution Approach 1:
The peg is designed with two distinct cam portions (first cam portion with first cam surface, and second cam portion with second cam surface) that have different geometric profiles. The first cam surface is optimized for the release function while the second cam surface is optimized for the impulse function. This local differentiation allows each contact surface to have optimal geometry for its specific function, reducing friction and wear while maintaining manufacturing feasibility through a unified two-level structure.
2Device complexity
If conventional identical geometry is used for both release and impulse functions, then device complexity is reduced, but energy losses increase due to suboptimal contact surfaces
Solution Approach 1:
The invention introduces a vertical dimension by offsetting the first cam portion and second cam portion at different levels along the axis of rotation of the plate device. This two-level configuration allows independent optimization of contact surfaces for release and impulse functions without significantly increasing horizontal complexity. The different levels enable distinct geometric profiles while maintaining a compact integrated structure, thereby reducing energy losses through optimized contact geometry.
3Ease of manufacture
If conventional single-level peg design is used, then manufacturing is simpler, but friction increases due to non-optimized contact surfaces
Solution Approach 1:
The peg is segmented into two distinct cam portions positioned at different levels: the first cam portion with its cam surface optimized for release function, and the second cam portion with its cam surface optimized for impulse function. This segmentation allows each portion to have tailored geometry that minimizes friction for its specific function. The segmented design is manufactured as an integrated component with offset levels, maintaining manufacturing simplicity while achieving superior friction reduction compared to single-level designs.
4Ease of operation
If conventional geometry optimized for clearance is used, then clearance function is improved, but impulse function is not optimized leading to increased wear
Solution Approach 1:
The first cam portion and second cam portion are designed with different geometric profiles tailored to their specific functions. The first cam surface geometry is optimized for the clearance function to ensure proper anchor disengagement, while the second cam surface geometry is optimized for the impulse function to minimize wear during energy transmission. This local optimization of each cam portion's geometry allows both functions to perform at their best without compromise.
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 configuration reduces wear, energy losses, and power consumption, enhancing the efficiency and reliability of the escapement mechanism, with potential efficiency improvements of 3-5% for frequencies above 3 Hz by optimizing the release and impulse functions independently.
Implementation Method 1
The peg includes a first cam portion configured to engage the first horn, and a second cam portion configured to engage the second horn. The first cam portion includes a first cam surface configured to engage the first horn at a first ankle level, and the second cam portion includes a second cam surface configured to engage the second horn at a second ankle level.
Implementation Method 2
The first and second levels are offset in a direction parallel to the axis of rotation (A) of the plate device. The optimization of the geometry of the contact surfaces between the pin and the fork aims in particular to reduce friction in order to reduce the wear of the parts.
Data Source
Figure 1
Figure 2
Figure 3(a)~3(c)
AI summary
Escapement mechanism (3) for a watch movement including a pallet lever (7) with a fork (13) and a roller device (4) with an impulse-pin coupled to a balance (2). The fork includes an entry horn (19) and an exit horn (21), the impulse-pin including a first cam portion (12a, 12b) configured to engage the entry horn, and a second cam portion (14a, 14b) configured to engage the exit horn. The first cam portion includes a first cam surface (12a) configured to engage the entry horn on a first level (10a, 10b), and the second cam portion includes a second cam surface (14b) configured to engage the exit horn on a second level (10b, 13b), the first and second levels being staggered in a direction parallel to the axis of rotation (A) of the roller device.