Compact Crossbow Inverted String Release for Extended Draw
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Solution Overview
Problem
Conventional crossbows have a limited draw length due to the string release location, resulting in a bulky and heavy design that is difficult to maneuver, necessitating a more compact and elongated-draw crossbow with a longer power stroke.
Innovation Solution
A compact crossbow design featuring a riser, split limbs, cams, a string release mechanism, and rotating string covers that allow for a longer draw length while maintaining a compact size, with the string release positioned behind the shooter's face for safety and the string covers encasing the string to prevent contact during firing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the string release is positioned in front of the butt end of the crossbow stock, then the draw length is sufficient for the bow string to be in front of the shooter's face, but the overall length of the crossbow increases making it bulky and difficult to maneuver
Solution Approach 1:
The string release is inverted from its conventional position in front of the butt end to a position behind the shooter's face. This inversion allows the draw length to be extended while the physical footprint of the crossbow is reduced, resolving the contradiction between draw length and overall size.
Solution Approach 2:
The string release mechanism is repositioned along the longitudinal axis of the crossbow, moving from the forward position to the rearward position behind the shooter's face. This dimensional repositioning enables the bow string to extend further back, effectively increasing draw length without increasing the forward projection of the crossbow, thus reducing overall size.
2Duration of action of moving object
If the string release is positioned in front of the butt end of the crossbow stock, then the draw length is limited to less than 17 inches, but positioning it behind the shooter's face enables a longer power stroke
Solution Approach 1:
The string release is inverted from a forward position to a rearward position behind the shooter's face. This inversion extends the power stroke length while the trigger mechanism maintains operational accessibility through the stock structure, resolving the contradiction between power stroke length and ease of operation.
3Power
If the crossbow is designed with a longer draw length, then the power stroke is extended, but the crossbow becomes bulky and heavy
Solution Approach 1:
The string release and bow string are inverted to a rearward position, enabling extended power stroke without requiring additional forward structural support. This reduces the overall mass distribution and allows for a more compact, lighter design while maintaining extended power stroke capability.
Solution Approach 2:
The power stroke is extended along the longitudinal dimension by repositioning the string release behind the shooter's face, rather than increasing the transverse or vertical dimensions. This dimensional efficiency allows for extended power stroke without proportionally increasing overall weight.
Data Source
AI summary
An improved elongated-draw compact crossbow (150) includes a riser (101), stirrup (100), right and left split limbs (102) each having a first end coupled to the riser (101), right and left cams (104 and 103) with axles coupled to respective second ends of the right and left split limbs (102), string (105) and harness coupled to right and left cams (104 and 103), and a rifle-type stock (110) with a substantially rectangular-shaped barrel (109) having a bore end and butt end and being coupled to the stock (110). When the string (105) of the crossbow (150) is fully drawn and cocked, covers (108 and 107) may be pivoted on the cylindrical rods of respective brackets (106) until they rest against the side of the barrel (109) and cover the string (105) when cocked. Another improved elongated-draw compact crossbow (160) includes a single cover (113) coupled to a hinge (112) the top side of the barrel (109) that rotates on the hinge (112) down until it rests against the top side of the barrel (109) and two portions of the cover (113) extend down over the string (105) when cocked.