Self-Timing Cam and Cable Configuration for Archery
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Solution Overview
Problem
Existing archery and crossbow technologies face issues with cam lean and timing due to cable interference and inefficient tensioning, which affects the performance and assembly of shooting bows and crossbows.
Innovation Solution
A self-timing cam and cable configuration where both ends of each cable are anchored to the same cam, allowing the cam to rotate at least 200 degrees, with a mid-portion of the cable slidably engaging a pulley to eliminate cam lean and ensure automatic timing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If cables are connected to opposing cams with crossing arrangement, then cable tensioning is achieved, but cam lean and twisting torque are created
Solution Approach 1:
The patent removes the harmful crossing arrangement of cables from the system. By anchoring both ends of each cable to the same cam and routing them through pulleys, the cables no longer cross each other, eliminating the source of twisting torque and cam lean while maintaining cable tensioning functionality.
Solution Approach 2:
The patent introduces pulleys as intermediary components between the cables and cams. The pulleys serve as mediators that redirect cable forces without requiring cable crossings, thereby eliminating harmful twisting moments on cam axles while preserving the tensioning function.
2Object-affected harmful factors
If cables are routed to avoid interference with arrow flight, then arrow flight path is clear, but cable timing becomes difficult to adjust
Solution Approach 1:
The patent creates a self-timing system where the cable arrangement automatically synchronizes cam operation. By anchoring both ends of each cable to the same cam and routing through pulleys, the system self-regulates cable timing without requiring manual adjustment, eliminating the time-consuming timing process while keeping cables clear of the arrow path.
3Length of stationary object
If cam rotation is limited to less than 360 degrees, then cable track width is reduced, but cam rotation range is restricted
Solution Approach 1:
The patent solves the space constraint problem by changing the cable routing dimension. Instead of requiring wider cable tracks to accommodate full 360-degree cam rotation, the pulley system redirects cables in a different spatial arrangement, enabling complete cam rotation without increasing track width requirements.
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 shooting bow with reduced cam lean and automatic cable timing, enhancing performance and ease of assembly by allowing the cams to rotate 360 degrees without cable interference, thus improving the efficiency and usability of the projectile launching device.
Implementation Method 1
a mid-portion of first and second cables slidably engaging a 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 slideably 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.