Flexible Cable Guard for Compound Bow Limb Force Reduction
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Solution Overview
Problem
Traditional cable guards in compound bows apply excessive force to the bow limbs, leading to undesirable nock travel and accuracy issues due to the shorter axle-to-axle distance in modern designs, necessitating a reduction in forces applied to the free ends of the bow limbs.
Innovation Solution
A cable guard design featuring a mounting portion, a flexible main body made of composite materials like fiberglass or spring steel, and a cable engaging portion with rollers, which biases the power and secondary payout cables away from the riser, allowing them to deflect inwardly during draw, minimizing contact with the arrow and reducing limb tip displacement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If fixed, relatively stiff cable guards are used to displace power cables laterally, then the cables are moved out of the shooting plane and prevented from contacting the arrow, but excessive force is applied to the rotatable members and bow limb tips, resulting in undesirable nock travel during arrow launch
Solution Approach 1:
The cable guard employs a flexible blade constructed from composite materials that can bend and flex during the drawing cycle. This flexibility allows the cable guard to displace the power cable laterally when needed while accommodating the dynamic movements of the bow during operation, thereby reducing excessive forces on the limb tips and improving nock travel stability.
Solution Approach 2:
The invention changes the physical parameters of the cable guard by using composite materials with specific flexural properties. The blade's flexibility parameter is optimized to provide sufficient cable displacement while allowing controlled movement during draw, reducing the force transmission to the bow components and eliminating undesirable nock travel.
2Area of stationary object
If traditional cable guards are used in modern compound bows with shorter axle-to-axle distance, then cable displacement is achieved, but the negative effects are amplified due to reduced distance between rotatable members
Solution Approach 1:
The flexible blade design allows the cable guard to adapt to the compact geometry of modern bows with shorter axle-to-axle distances. The flexibility enables effective cable displacement in the limited space available while distributing forces more evenly, preventing concentration of excessive forces on the limb tips that would be amplified by the reduced distance between rotatable members.
Solution Approach 2:
The cable guard blade is constructed from composite materials that provide the necessary combination of strength and flexibility. These composite materials enable the blade to maintain structural integrity while providing the required flexural compliance, effectively addressing the force concentration issue in compact bow designs where traditional stiff materials would exacerbate the problem.
3Stability of the object's composition
If stiff cable guards are used to maintain cable position, then cable stability is improved, but arrow launch consistency deteriorates due to increased nock travel
Solution Approach 1:
The flexible blade maintains cable position stability through its ability to conform to the dynamic geometry of the bow during operation. Rather than rigidly holding the cable in a fixed position, the flexible material provides stable cable displacement while accommodating the natural movements of the bow, thereby preventing excessive nock travel and improving arrow launch consistency and precision.
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 flexible cable guard design significantly reduces the forces applied to the bow limbs, minimizing horizontal displacement of the arrow nock and improving accuracy by keeping the cables out of the arrow's flight path, even at full draw, thereby enhancing the consistency and precision of arrow launch.
Implementation Method 1
The main body portion (46) is comprised of a flexible material... the flexible material has a modulus of elasticity between about 5×10^6 kPa and 6.5×10^6 kPa... the cable engaging portion moves to a second position, the second position being closer to the plane of the bowstring than the first position
Implementation Method 2
a cable guard comprising a mounting portion attached to the riser, a flexible portion and a roller contacting the cable
Data Source
AI summary
In some embodiments, a compound archery bow comprises a riser, first and second limbs and first and second rotatable members. A bowstring extends between the first rotatable member and the second rotatable member. A power cable is biased in a direction away from the riser by a cable guard comprising a mounting portion attached to the riser, a flexible portion and a cable engaging portion. In some embodiments, the cable guard comprises a roller.