Compound Bow Synchronized Cam Draw Stop
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Solution Overview
Problem
Synchronized dual-cam archery bows with power cables anchored to the cams can experience a cam-lock situation where the draw force on the bowstring is completely released, locking the cams at full draw with no tension, if the cams are rotated too far, leading to undesirable conditions.
Innovation Solution
A pulley assembly with a draw stop mechanism is integrated into the take-up cam to limit the rotation of the pulley at full draw, preventing the cam-lock situation by engaging against the power cable, thereby maintaining tension in the bowstring.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the cam is allowed to rotate freely to achieve complete let-off of draw force, then the draw force on the bowstring is fully released, but the cam locks at full draw with no tension on the bowstring
Solution Approach 1:
The draw stop is positioned to engage the power cable before the cam can rotate far enough to cause complete let-off and locking. This preliminary counter-action prevents the harmful cam-lock condition from occurring in the first place, while still allowing the cam to rotate sufficiently to achieve the desired let-off effect.
Solution Approach 2:
The draw stop acts as an intermediary element between the cam and the power cable. It mediates the interaction by selectively engaging the cable at the appropriate moment to prevent over-rotation and cam-locking, while allowing normal operation and let-off to occur when needed.
2Reliability
If a draw stop mechanism is added to prevent cam-lock, then cam rotation is limited and bowstring tension is maintained, but the pulley assembly complexity increases
Solution Approach 1:
The draw stop is integrated into the existing pulley assembly structure, combining the cam mechanism with the draw stop function in a unified design. This merging approach prevents cam-locking while minimizing the increase in overall device complexity by utilizing the existing structural framework.
Solution Approach 2:
The draw stop serves multiple functions: it limits cam rotation to prevent cam-locking, maintains bowstring tension, and works with the existing power cable system. This multi-functionality reduces the need for separate dedicated components, thereby limiting the increase in device complexity.
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 draw stop effectively prevents the cam-lock condition, ensuring consistent bowstring tension and preventing the need for complex recalibration or tool-assisted corrections, enhancing user safety and operational reliability.
Implementation Method 1
a first draw stop at one end of the first take-up cam... engaging against a power cable limiting rotation of the pulley at full draw
Implementation Method 2
a pulley assembly coupled to the limb for rotation around an axis
Implementation Method 3
maintaining tension in the bowstring
Data Source
AI summary
A compound archery bow that includes: a bow handle, a limb projecting from the bow handle, and a pulley assembly coupled to the limb for rotation around an axis. The pulley assembly may be include a bowstring cam including a bowstring track in a bowstring plane, a let-out cam carried by the bowstring cam and including a let-out track in a let-out plane spaced apart from the bowstring plane, an arcuately-shaped first take-up cam arcuately adjustably coupled to the bowstring cam and including a first take-up track in a take-up plane, and a first draw stop at one end of the first take-up cam.