Crossbow Drawstring Guide Pulley Mechanism
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Solution Overview
Problem
Existing crossbows face inefficiencies, safety issues, left-to-right draw movement, and handling and transporting difficulties due to their size and design.
Innovation Solution
A crossbow design featuring a first stock portion with a horizontal projectile plane, a rotatable drawstring hub, and flexible limbs with power cables, along with drawstring guides that include pulley wheels, to improve efficiency, balance, safety, and accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the length and weight of the limbs are increased to maintain adequate power stroke, then the power and energy storage are improved, but the overall width and weight of the crossbow increase, making handling and transporting more difficult
Solution Approach 1:
The crossbow is divided into modular components including a takedown stock that can be separated into multiple sections. This segmentation allows the crossbow to be disassembled for easier transport and storage while maintaining full power stroke capability when assembled, resolving the contradiction between power requirements and portability.
Solution Approach 2:
The patent introduces a vertical dimension for limb orientation and a modular stock that can collapse along the longitudinal axis. By utilizing multiple dimensions for compacting (rather than just reducing size in one direction), the crossbow maintains power stroke length while reducing overall transport dimensions and weight distribution.
2Ease of operation
If the crossbow is made narrower to improve handling and transporting, then the portability is improved, but guiding the draw string becomes more difficult and left-to-right movement increases, reducing accuracy
Solution Approach 1:
Draw string guides are introduced as intermediary components that mediate between the narrow crossbow body and the draw string. These guides ensure precise draw string alignment and prevent left-to-right movement even in a compact configuration, resolving the contradiction between narrow design and guidance precision.
Solution Approach 2:
The draw string guides are designed with dynamic characteristics that allow them to adapt to the draw string's movement path. This dynamic guidance system maintains precision across the narrow body width by flexing and adjusting to the draw string's trajectory during the power stroke.
3Volume of moving object
If existing camming means are used to reduce draw string wear and make the crossbow narrow, then the portability is improved, but left-to-right movement of the drawstring occurs, reducing accuracy
Solution Approach 1:
Draw string guides serve as intermediary components between the camming mechanism and the draw string, preventing left-to-right movement while maintaining the compact narrow design. These guides ensure the draw string follows the correct path without deviating laterally, preserving accuracy in a compact configuration.
Solution Approach 2:
The draw string guides are positioned to create an equipotential path for the draw string, ensuring that the draw string experiences consistent lateral forces throughout its travel. This prevents unwanted left-to-right movement and maintains alignment precision throughout the power stroke in the compact design.
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 design enhances the crossbow's compactness, accuracy, and efficiency while improving safety and reducing the left-to-right movement of the drawstring, making it easier to handle and transport.
Implementation Method 1
first and second drawstring guides each include a pulley wheel, wherein the drawstring is guided at least partially around each pulley wheel
Data Source
AI summary
A crossbow is configured to shoot a projectile. The crossbow includes a frame having a stock positioned at a rear end, the frame defining a horizontal projectile plane at a top side in which a projectile axis is positioned. The projectile moves within the horizontal projectile plane and along the projectile axis during firing and arming of the crossbow, and the projectile is fired from a front end of the frame. The crossbow further includes a drawstring hub connectable to ends of a drawstring. Rotation of the drawstring hub in at least one direction is powered, such as by a force applied by flexed limbs. The crossbow further includes drawstring guides attached to the frame for guiding the drawstring across the projectile axis between the ends of the drawstring. The first and second drawstring guides each include a pulley wheel, wherein the drawstring is guided at least partially around each pulley wheel. A further aspect is a crossbow having a frame comprised of a first frame portion and a second frame portion that are detachably coupled to one another via a fastening mechanism.