Archery Bow Cam With Opposing Capstan Rotation
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Solution Overview
Problem
Existing archery bow designs lack sufficient adjustability to accommodate a wider range of users and do not provide a sufficient range of draw weights and draw lengths, limiting their versatility and adaptability.
Innovation Solution
The design incorporates a cam configuration with rotatable members, power cables, and adjustable modules that allow for greater adjustability, including a capstan and terminal system where the power cables wrap around the capstan in a direction opposite to the cam rotation, enabling a broader range of draw weights and lengths by utilizing a riser, first and second limbs, and axles that define an axle plane, with the cam track and capstan portions aligned for optimal performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a traditional fixed cam design is used, then the bow structure is simple, but the adjustability for different users is limited
Solution Approach 1:
The patent applies dynamics by making the cam structure adjustable rather than fixed. The rotatable member can be positioned at different locations along the limb, and the cam track geometry can be modified, allowing the bow to adapt to different users' draw weights and draw lengths while maintaining a relatively simple overall structure
Solution Approach 2:
The cam is segmented into multiple functional components: a rotatable member with a cam track, a capstan portion, and a terminal. This segmentation allows each component to be optimized independently and adjusted to achieve the desired draw characteristics for different users
2Adaptability or versatility
If the cam rotation direction is fixed, then the power cable routing is simple, but the range of achievable draw weights and lengths is limited
Solution Approach 1:
The patent applies inversion by having the power cable wrap around the capstan in a direction opposite to the cam rotation direction. This counter-intuitive arrangement enables the system to achieve a broader range of draw weights and lengths by utilizing the opposite rotational directions to create more varied mechanical advantage ratios
Solution Approach 2:
The invention adds a dimensional aspect to the cable routing by introducing the capstan as a separate rotational element from the cam. The power cable wraps around the capstan in one rotational direction while the cam rotates in the opposite direction, creating a two-dimensional rotational system that expands the achievable parameter range
3Ease of operation
If the terminal is positioned close to the axle, then the structural compactness is improved, but the rotation capability is limited
Solution Approach 1:
The capstan is designed with a curved surface that the power cable wraps around. This curvature allows the cable to follow a longer path around the capstan, effectively increasing the rotation capability and mechanical advantage without requiring the terminal to be positioned far from the axle, thus maintaining structural compactness
Data Source
AI summary
In at least one embodiment, an archery bow includes a rotatable member comprising a cam track, a capstan and a terminal. A drawstring extends from the first rotatable member. A power cable is attached to the terminal and extends away from the rotatable member. The power cable comprises an elongate straight portion located near the rotatable member, a capstan portion in contact with said capstan and a terminal portion in contact with said terminal. In a brace condition, the power cable wraps around the capstan in a first rotational direction as the power cable is traversed from the elongate straight portion to the terminal portion. When the bow is drawn from the brace condition, the rotatable member rotates in a second rotational direction that is opposite the first rotational direction.