Projectile Launching Device Self-Timing Cable Mechanism
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Solution Overview
Problem
Existing archery and crossbow technologies face issues with cam lean and timing due to cable interference, inefficiencies in tensioning, and the need for precise cable adjustments to maintain proper timing, particularly with multiple cables.
Innovation Solution
A self-timing projectile launching device with a unique cable arrangement where neither end of the cable is rigidly attached to the cam, featuring a harness system with first and second cams, upper and lower cable posts, and a launch string that allows the cables to 'float' and self-center, eliminating cam lean and cable crossing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If cables are connected to opposing cams and cross the centerline to maintain proper timing, then timing between limbs is improved, but cam lean and twisting torque in the cam axle increases
Solution Approach 1:
The patent moves the cable attachment points from the cam perimeter to cable posts positioned above and below the cam plane. This dimensional relocation allows cables to approach the cam from perpendicular directions rather than crossing at angles, eliminating cam lean while preserving timing through the vertical cable post arrangement.
2Power
If multiple cables are used to provide proper tensioning and timing, then energy storage and launch efficiency is improved, but cable timing becomes difficult to maintain and requires frequent adjustments
Solution Approach 1:
The cable posts are positioned above and below the cam plane rather than on the cam perimeter. This self-service arrangement allows the cables to naturally align and self-time as they wrap around the cam, eliminating the need for precise manual timing adjustments while maintaining proper tensioning and energy storage.
3Power
If cables are routed to cross the centerline for proper mechanical advantage, then power transmission is improved, but cable interference with arrow flight occurs
Solution Approach 1:
The patent extracts the cable attachment function from the cam perimeter and relocates it to dedicated cable posts positioned above and below the cam plane. This separation removes cables from the horizontal centerline area, preventing interference with arrow flight while preserving power transmission through the vertical cable routing.
4Stability of the object's composition
If cables are rigidly attached to cams for stable tensioning, then mechanical stability is improved, but timing adjustments become time-consuming and difficult
Solution Approach 1:
The patent employs a dynamic cable arrangement where cables are not rigidly fixed to the cam but instead wrap around it from posts above and below. This dynamic configuration allows the cables to self-adjust and self-time as the cam rotates, maintaining stable tensioning throughout the cycle while eliminating time-consuming manual timing adjustments.
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 solution provides a self-timing, cam-lean-free mechanism that simplifies cable management and eliminates the need for precise adjustments, enhancing performance and usability by ensuring the cables do not interfere with the arrow's flight and maintaining efficient tensioning.
Implementation Method 1
The present invention may alternately use components other than flexible limbs for storing energy prior to launching the projectile
Data Source
AI summary
A projectile launching device includes self-timing without cam lean. The projectile launching device includes a riser, a rail, two energy storing components, (such as two limbs), two cams, a launch string, and least one cable. The ends of the launch string are attached to the two cams. Opposing ends of first and second cables are coupled to the rail. A mid-portion of the first and second cables are slidably engaged with the first and second cams, respectively. Alternatively, a single cable may replace the first and second cables. 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.