Archery Bow Circular String Track Timing Error Reduction
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Solution Overview
Problem
Existing archery bows, particularly compound bows, face inefficiencies due to timing errors between rotating members, leading to a less-than-smooth shooting experience and suboptimal performance.
Innovation Solution
The design incorporates a first and second rotatable member with bowstring tracks having constant radii and centers on their respective axes, minimizing timing errors and providing a consistent moment arm for a smoother draw, while allowing for adjustable modules to customize draw characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional rotating members with variable radius tracks are used in compound bows, then the bow can achieve cam action for energy storage and release, but timing errors between rotating members occur leading to rough shooting experience
Solution Approach 1:
The patent applies circular arc tracks instead of traditional cam-shaped tracks. The bowstring track is defined as a circular arc with constant radius centered on the rotation axis, creating a perfectly round path for the bowstring to follow. This circular geometry eliminates the variable radius cam action that causes timing sensitivity, providing consistent rotational motion regardless of timing variations between limbs.
Solution Approach 2:
The patent changes the geometric parameter of the bowstring track from variable radius (cam shape) to constant radius (circular arc). This parameter change transforms the mechanical action from caroming cam engagement to smooth circular rotation, reducing sensitivity to timing errors and improving the consistency of the draw experience.
2Use of energy by moving object
If cam tracks with variable radius are used, then energy storage and release can be optimized, but timing errors between rotating members have greater impact on performance
Solution Approach 1:
The circular arc track geometry provides consistent rotational mechanics that reduce timing sensitivity. The constant radius ensures that the bowstring follows a predictable circular path, making the energy transfer more reliable and less dependent on precise synchronization between rotating members.
Solution Approach 2:
The patent converts the harmful effect of timing errors into a beneficial outcome by using circular tracks that are inherently insensitive to timing variations. What was previously a source of inconsistency (timing errors) becomes irrelevant in the circular geometry, allowing the bow to maintain consistent performance across varying draw conditions.
3Ease of operation
If constant radius circular tracks are used, then timing errors are minimized and draw smoothness is improved, but traditional cam action for energy storage is reduced
Solution Approach 1:
The circular arc track maintains the rotational mechanism while changing the track geometry from cam-shaped to circular. This allows the rotating members to still provide mechanical advantage and energy storage through rotation, while the constant radius eliminates timing sensitivity and improves draw smoothness.
Solution Approach 2:
The patent maintains dynamic rotational motion of the members while changing the static geometry of the track from variable to constant radius. The rotating members still provide dynamic energy storage and release, but the circular track ensures this occurs with consistent mechanics regardless of timing variations.
Data Source
AI summary
In some embodiments, an archery bow comprises a riser, a first limb supported by the riser and a second limb supported by the riser. A first rotatable member is supported by the first limb and arranged to rotate on a first axis and a second rotatable member is supported by the second limb and arranged to rotate on a second axis. The first rotatable member comprises a first bowstring track comprising a first portion and a second portion, the first portion having a constant radius and a center located on the first axis, the second portion having a varying radius. A bowstring comprises a first end attached to the first rotatable member and a second end attached to the second rotatable member.