Projectile Launching Device Self-Timing Cam Cable Configuration
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Solution Overview
Problem
Existing archery and crossbow technologies face issues with cam lean and inefficient cable timing, leading to parasitic energy loss and complex adjustment processes, particularly when cams rotate beyond 200 degrees and cables cross the centerline.
Innovation Solution
A self-timing cam and cable configuration where both ends of each cable are anchored to the same cam, with a mid-portion sliding on a pulley, allowing cams to rotate 360 degrees without crossing the centerline, and utilizing a unique cable retention system to maintain optimal cable alignment and tension.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If cables are connected to opposing cams and cross the centerline to achieve binary cam system efficiency, then energy transfer efficiency is improved, but cam lean and twisting torque are created
Solution Approach 1:
The patent extracts the cables from the centerline region by routing them along the outer periphery of the cams. The cables are connected to opposing cams but are positioned to run along the external circumference rather than crossing the centerline, thereby eliminating the source of cam lean and twisting torque while preserving the binary cam system's energy transfer efficiency
Solution Approach 2:
The patent transitions the cable routing from a planar configuration that crosses the centerline to a three-dimensional arrangement that follows the outer periphery of the cams. This dimensional change allows the cables to maintain their functional connection between opposing cams while avoiding the harmful interactions that occur when they cross the centerline
2Adaptability or versatility
If cables are routed to allow cams to rotate beyond 200 degrees, then rotational range is improved, but cable timing complexity and adjustment difficulty increase
Solution Approach 1:
The patent incorporates preliminary timing features into the cable routing system, where the cables are pre-positioned and pre-tensioned to automatically maintain correct timing across the full range of cam rotation. This preliminary configuration eliminates the need for complex post-assembly adjustments and simplifies the timing mechanism while allowing cams to rotate beyond 200 degrees
Solution Approach 2:
The cable routing system is designed to self-time the cams during operation, automatically maintaining proper synchronization without requiring external adjustment mechanisms. The geometric arrangement of the cables along the cam periphery creates inherent timing characteristics that adapt to the full rotational range, making the system self-regulating
3Object-affected harmful factors
If cables are positioned off-angle to avoid interfering with arrow flight, then arrow clearance is improved, but twisting and torque in cam axle are created
Solution Approach 1:
The patent resolves the spatial conflict between cables and arrow flight path by transitioning the cable routing to the outer periphery of the cams, utilizing the three-dimensional space around the cam assembly rather than the two-dimensional plane that would require cables to cross the centerline. This dimensional repositioning provides adequate arrow clearance while maintaining cable alignment that prevents twisting and torque
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 eliminates cam lean, minimizes parasitic energy loss, and simplifies the adjustment process, ensuring precise timing and efficient energy transfer during the release cycle, while allowing for smooth cable movement and reduced vibration.
Implementation Method 1
The cables are allowed to slideably engage the pulleys, which allows the cables to self-time and eliminates cam lean
Implementation Method 2
a first cable, wherein both ends of the first cable are anchored to the first cam, and a mid-portion of the first cable at least partially wraps a first cable pulley
Data Source
AI summary
A projectile launching device includes self-timing without cam lean. The projectile launching device preferably includes a rail, a riser, two energy storing components, (such as two limbs), two cams, a launch string, and at least two cables. The ends of the launch string are attached to the two cams. Opposing ends of first and second cables are coupled to the first and second cams. A mid-segment of the first and second cables are slidably engaged with the first and second cable pulleys, respectively. The two cams are preferably built as mirror images of each other at a centerline of the rail. The two cams include a launch string track, having identical, but mirrored, upper and lower cable tracks.