Adjustable Pulley Assembly for Compound Bow Draw Force Control
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Solution Overview
Problem
Existing adjustable pulley assemblies for compound archery bows do not provide sufficient fine adjustment of draw force let-off rate with respect to draw distance or hold weight at full draw, and often require derigging the bow or using a bow press for adjustments.
Innovation Solution
An adjustable pulley assembly with a draw cable pulley, a power cable pulley, and an adjustable cable deflector that allows for multiple deflector arrangements, enabling adjustments to the let-off rate and hold weight without derigging the bow or using a bow press, by allowing the cable deflector to engage the power cable during the let-off portion of drawing, altering the effective lever arm for take-up of the power cable.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If existing adjustable pulley assemblies are used, then basic adjustability is provided, but fine adjustment of draw force let-off rate and hold weight is insufficient
Solution Approach 1:
The cable deflector is made adjustable with multiple possible arrangements (at least two different positions) allowing the system to dynamically change its configuration. This enables fine adjustment of the draw force curve characteristics including let-off rate and hold weight, resolving the contradiction by providing both precision through multiple discrete positions and versatility through the ability to select different arrangements.
Solution Approach 2:
The invention changes the geometric parameters of the pulley assembly by repositioning the cable deflector to different arrangements. This alters the effective lever arm for power cable take-up, thereby changing the draw force curve parameters (let-off rate and hold weight). This parameter change approach enables precise control over bow performance characteristics while maintaining adjustability.
2Adaptability or versatility
If traditional adjustment methods are used, then pulley assembly configuration can be changed, but the process requires derigging the bow or using a bow press
Solution Approach 1:
The pulley assembly is segmented into adjustable components, specifically the cable deflector that can be repositioned between multiple arrangements. This segmentation allows the adjustment function to be isolated and simplified, enabling configuration changes without requiring complete disassembly (derigging) or specialized equipment like a bow press, thus improving ease of operation while maintaining adaptability.
Solution Approach 2:
The cable deflector is designed with dynamic repositioning capability, allowing users to switch between at least two different arrangements directly on the assembled bow. This dynamic feature eliminates the need for static, complex adjustment procedures and enables simple field adjustments without derigging or specialized tools.
3Measurement precision
If the cable deflector engages the power cable during let-off portion, then fine adjustment of draw force curve is enabled, but the structure becomes more complex
Solution Approach 1:
The cable deflector serves multiple functions: it guides the power cable during normal operation and also provides adjustment capability when repositioned to different arrangements. This multi-functionality reduces the need for separate adjustment mechanisms, thereby enabling precise draw force control without proportionally increasing structural complexity.
Solution Approach 2:
The adjustable cable deflector configuration allows the pulley assembly to self-adjust its geometry to achieve different draw force curves. The structure uses its own components (cable deflector, power cable, pulleys) to create the adjustment mechanism, eliminating the need for additional complex external adjustment devices.
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
Enables precise adjustment of draw force curves with respect to let-off rate and hold weight, providing archers with customizable performance without the need for complex setup or disassembly, enhancing the usability and adjustability of compound archery bows.
Implementation Method 1
a draw cable pulley... be mounted on a first limb of an archery bow to rotate about the first pulley assembly axis, and let out, from a circumferential draw cable journal of the draw cable pulley, a draw cable of the archery bow when the bow is drawn
Implementation Method 2
a power cable pulley... take up, during at least a portion of drawing of the bow, into a circumferential power cable journal of the power cable pulley, a power cable of the archery bow
Implementation Method 3
the power cable pulley is structurally arranged and positioned on the draw cable pulley so as to take up... a power cable of the archery bow
Implementation Method 4
the cable deflector engages the power cable for further take-up thereof during a let-off portion of drawing of the bow after the power cable is taken up by the power cable pulley... altering the effective lever arm for take-up of the power cable
Data Source
AI summary
A pulley assembly for a compound bow comprises a draw cable pulley, a power cable pulley attached to the draw cable pulley, and a cable deflector attached to the power cable pulley or the draw cable pulley and adjustable among multiple deflector arrangements. The cable deflector engages the power cable during a let-off portion of drawing of the bow after the power cable is taken up by the power cable pulley. Different deflector arrangements result in corresponding draw force curves for the bow that differ from one another with respect to one or both of (i) draw force let-off rate with respect to draw distance or (ii) hold weight at full draw. The adjustment can be performed without using a bow press and without derigging the bow.