Compound Bow Pulley Block with Dynamic Couplers
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Solution Overview
Problem
The efficiency of existing compound bows is difficult to further improve due to the invariable draw force curve and energy storage capacity of traditional pulley blocks.
Innovation Solution
A compound bow design featuring two pulleys for cable, with a first and second coupler that dynamically couple and decouple the pulleys for cable with the pulley for string, allowing for adjustable draw force characteristic curves and enhanced energy storage capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If traditional pulley blocks with fixed pulleys are used, then the structure is simple, but the draw force curve and energy storage capacity are invariable
Solution Approach 1:
The patent applies dynamics by making the pulley block structure movable and adjustable. The cable pulley can shift positions along the limb relative to the string pulley, changing the mechanical advantage ratio dynamically during the drawing process. This allows the draw force curve to be adjusted from fixed to variable, enabling different let-off percentages and energy storage characteristics without requiring multiple fixed pulley configurations.
Solution Approach 2:
The patent segments the pulley block into separate cable pulley and string pulley components that can move independently relative to each other. This segmentation allows the cable pulley to be positioned at different locations along the limb, creating multiple possible draw force curves. The modular design enables flexibility in configuring the bow's performance characteristics while maintaining a relatively simple overall structure.
2Ease of operation
If the draw force is reduced gradually during drawing for anchoring, then anchoring is easier, but the pulley block stores less energy
Solution Approach 1:
The dynamic positioning of the cable pulley allows the draw force curve to be optimized for both anchoring ease and energy storage. By adjusting the cable pulley position, the system can maintain higher draw force for longer during the drawing stroke to maximize energy storage, while still providing adequate let-off at full draw to facilitate anchoring. This resolves the contradiction by making the force profile adaptive rather than fixed.
Solution Approach 2:
The patent changes the parameter of cable pulley position along the limb to optimize the draw force curve. By varying this positional parameter, the system can achieve different balances between energy storage capacity and anchoring ease. The optimal position allows the bow to store maximum energy while maintaining sufficient let-off for comfortable anchoring, resolving the trade-off between these two requirements.
3Adaptability or versatility
If fixed geometry pulleys are used, then manufacturing is simple, but mutational draw force curve cannot be realized
Solution Approach 1:
Instead of manufacturing complex variable-geometry pulleys, the patent achieves mutational draw force curves through the dynamic positioning of standard geometry pulleys. The cable pulley can be positioned at different locations along the limb using simple mechanical guides or adjustment mechanisms, allowing multiple draw force curves to be realized with relatively simple manufacturing requirements while achieving the desired variability in performance characteristics.
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 design enables a shift in draw force characteristic curves within a single shooting loop, allowing for adjustable energy storage capacity and conversion efficiency, thereby improving the overall performance of the compound bow.
Implementation Method 1
a pulley block, a string, a cable... through the backward pulling and deformation of the string, the kinetic energy, with which the bow is drawn, may be converted into the potential energy, with which the two cables are radially pulled
Implementation Method 2
By means of the pulley block of the compound bow, a draw force curve may be improved and labor may be saved
Implementation Method 3
a first coupler, a second coupler... configured to keep the first pulley for cable and the pulley for string in a coupled state before the pulley for string is pulled to a set position while decoupling the first pulley for cable and the pulley for string after the pulley for string is pulled to the set position
Data Source
AI summary
A compound bow includes a riser, a limb, a pulley block, a string, a first coupler, a second coupler, a first cable and a second cable, the pulley block includes a pulley for string, a first pulley for cable and a second pulley for cable, the first pulley for cable and the second pulley for cable are located on two sides of the pulley for string respectively, the first coupler is configured to couple or decouple the first pulley for cable and the pulley for string at a set position, the second coupler is configured to couple or decouple the second pulley for cable and the pulley for string in the set position.