Bowstring Cam Arrangement for Compound Bows
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Solution Overview
Problem
Existing compound bows and crossbows face inefficiencies in energy transfer to projectiles due to mechanical losses in crossover strings and pulley mechanisms, which hinder achieving maximum arrow or bolt velocity for a given draw weight.
Innovation Solution
The design employs bowstring cams with power cord cam grooves, anchored to a fixed point, eliminating crossover strings and pulleys, resulting in continuous increase of draw weight to full draw, reducing mechanical losses and enhancing energy transfer to the arrow or bolt.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If crossover strings and pulley mechanisms are used in compound bows, then draw weight regulation is achieved, but mechanical losses increase and energy transfer efficiency decreases
Solution Approach 1:
The patent removes the crossover strings and pulley mechanisms from the compound bow system, eliminating the source of mechanical losses while maintaining draw weight regulation through a simplified cam and power cord arrangement
Solution Approach 2:
The patent replaces the complex pulley and crossover string mechanical system with a direct cam and power cord mechanism, reducing the number of moving parts and minimizing energy loss to friction
2Force
If multiple cam wheels and pulleys are used, then draw weight control is improved, but device complexity increases
Solution Approach 1:
The patent extracts and removes the unnecessary cam wheels and pulleys from the system, retaining only the essential cam and power cord components needed for draw weight control
Solution Approach 2:
The patent combines the functions of multiple separate components (cam wheels and pulleys) into a single integrated cam and power cord system, reducing complexity while maintaining functionality
3Force
If synchronizing cords and cross-over strings are used, then draw weight distribution is achieved, but energy transfer efficiency to projectile decreases
Solution Approach 1:
The patent removes the synchronizing cords and cross-over strings that cause energy loss, achieving energy transfer efficiency through a direct power cord connection from the cam to the limb
Solution Approach 2:
The patent replaces the indirect synchronizing cord mechanism with a direct power cord system that transfers energy more efficiently from the cam to the limb and ultimately to the projectile
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 achieves higher arrow or bolt velocity by minimizing mechanical losses and ensuring consistent energy transfer throughout the draw, optimizing the bow's efficiency and projectile performance.
Implementation Method 1
bowstring cams with bowstring cam grooves and power cord cam grooves
Data Source
AI summary
A compound bow or crossbow employs bowstring cams with bowstring cam grooves and power cord cam grooves. Preferably a pair of generally identical power cord cam grooves are positioned axially above and below the bowstring cam groove. The power cords are anchored to a fixed anchor point, e.g., a pylon, on the near end of the riser or on the near side of the crossbow bar or stock. The power cords do not cross over to the other limb. The reduction in the number of cam wheels and pulleys and in the number of strings or cords results in greater efficiency and higher transfer of energy from the bow to the arrow or bolt. There is no drop-off in pull weight at full draw. The bolt or arrow accelerates throughout the travel of the bowstring, resulting in significantly higher velocity.