Crossbow Stock Overlap Mechanism for Compact Design
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Solution Overview
Problem
Traditional crossbows are typically wide due to the positioning of the archery bow across the stock, making them bulky and limiting their compactness while maintaining performance characteristics like firing speed and longevity.
Innovation Solution
A compound crossbow design featuring rotatable members that overlap with the stock, allowing for a reduction in the width by having a distance between these members less than the stock's width, with one member passing through the stock's sidewall, enabling a more compact form without compromising performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the archery bow is positioned across the stock in traditional crossbow design, then the crossbow structure is simple and easy to manufacture, but the width dimension increases making the crossbow bulky
Solution Approach 1:
The patent repositions the bow from a lateral arrangement (across the stock) to a longitudinal arrangement (along the stock). The first and second limbs are positioned along the length of the stock rather than extending laterally, fundamentally changing the spatial dimension in which the bow components are arranged. This dimensional shift reduces the width dimension while maintaining structural functionality.
Solution Approach 2:
The patent integrates the bow components within the stock structure itself. The limbs are positioned along the stock and the string assembly is contained within the stock's longitudinal space. This nesting approach allows the bow to be embedded within the stock's volume rather than extending outward, reducing the external width dimension.
2Device complexity
If the bow is positioned across the stock, then the firing mechanism is straightforward, but the external dimensions of the crossbow increase
Solution Approach 1:
The patent transitions from a lateral bow arrangement to a longitudinal arrangement, changing the primary dimension from width to length. The limbs extend along the stock's length rather than across its width, and the string assembly is contained within the longitudinal volume of the stock, reducing overall crossbow volume.
Solution Approach 2:
The patent merges the bow and stock into a more integrated structure. The limbs are positioned along the stock and the string assembly is contained within the stock, creating a unified compact unit. This merging eliminates the need for separate lateral bow mounting structures, reducing overall volume.
3Area of stationary object
If rotatable members are used to reduce width, then the crossbow becomes more compact, but the mechanism complexity increases
Solution Approach 1:
The patent incorporates rotatable members (cams) that rotate during the draw cycle to control the string assembly's movement. These dynamic components enable the compact longitudinal arrangement by providing mechanical advantage and controlling the draw-back motion, achieving compactness through dynamic mechanical action rather than static structural arrangement.
Solution Approach 2:
The rotatable members serve multiple functions: they control the string assembly movement, enable the compact longitudinal arrangement, and maintain firing functionality. This multi-functionality justifies the added mechanism complexity by consolidating multiple roles into single components.
Data Source
AI summary
In some embodiments, a crossbow comprises a stock, a fire control assembly and a bow portion. In some embodiments, the bow portion comprises a prod, a first limb, a second limb, a first rotatable member and a second rotatable member. The crossbow comprises a drawn orientation wherein the first rotatable member overlaps with the stock. In some embodiments, a reference line oriented orthogonal to a shooting axis intersects the stock and the first rotatable member. In some embodiments, the reference line is parallel to a rotation axis of the first rotatable member.