Crossbow String Release Load Distribution and Safety
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Solution Overview
Problem
Prior art crossbow string releases suffer from premature wear and limited usable life due to the full load being borne by string release tangs at full draw, and they often require separate safety mechanisms and arrow retention systems, which can prevent re-cocking after a shot.
Innovation Solution
A string release assembly that distributes the load of the bowstring between the string horn and latch tangs, incorporating a safety mechanism that moves to the safe position during cocking, and integrates an anti-dry fire system to prevent firing without a loaded arrow, eliminating the need for a separate arrow retention spring.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the string latch bears the full load of the bowstring at full draw, then the crossbow can be cocked and held at full draw, but the bowstring and bowstring serving suffer substantial wear and have limited usable life
Solution Approach 1:
The load-bearing function is segmented between the string horn and the latch tangs. The string horn bears a portion of the bowstring load through its inclined surface, while the latch tangs provide securing engagement. This segmentation reduces the load on individual components, particularly the tangs, thereby reducing wear on the bowstring and extending its usable life.
Solution Approach 2:
The string horn acts as an intermediary component between the bowstring and the latch mechanism. Its inclined surface distributes the bowstring load across multiple contact points, including the tangs and the horn itself, rather than concentrating the full load on the tangs alone. This intermediary structure reduces stress concentration and wear.
2Reliability
If the safety is moved to the safe position after a shot, then the shooter can prevent accidental discharge, but the shooter cannot re-cock the bow
Solution Approach 1:
The safety plate's blocking function is made dynamic rather than static. During the cocking process, the bowstring's movement automatically overrides the safety plate's blocking action on the trigger, allowing re-cocking. After cocking, the safety plate returns to its normal blocking position. This dynamic behavior allows the safety to adapt to different operational phases without preventing intended actions.
Solution Approach 2:
The trigger bar is designed with a geometry that preliminarily accounts for the safety plate's position. The curved surface of the trigger bar allows it to ride over the safety plate during the cocking motion, anticipating the need to temporarily bypass the safety mechanism during this specific operation while maintaining safety during normal operation.
3Reliability
If a separate arrow retention spring is used, then the arrow can be retained in the barrel, but the device complexity increases with an independent anti-dry fire system
Solution Approach 1:
The arrow retention function and the anti-dry fire function are merged into a single integrated mechanism. The plunger, when engaged by the loaded arrow, simultaneously performs arrow retention and blocks the safety plate to prevent dry firing. This eliminates the need for a separate arrow retention spring and reduces overall device complexity while maintaining both safety functions.
Solution Approach 2:
The plunger component serves multiple functions: it retains the arrow in the barrel, blocks the safety plate to prevent dry firing, and provides a mechanical link between arrow loading and safety engagement. This multi-functionality reduces the number of components needed while ensuring both arrow retention and anti-dry fire protection work together seamlessly.
Data Source
AI summary
A crossbow 100 includes a rifle-style stock 22, barrel 23, bowstring 1, and a string release housing 21 with a novel string release assembly. The string release assembly in string release housing 21 includes a string latch 12 for retaining fully-drawn and cocked bowstring 1 against a string horn 19, a trigger 6 for releasing or shooting the arrow 2, a safety button 25 for the movement of the safety plate 7 from the safe position to the fire position, and a load lever 4 for loading the arrow 2. There is a safety button 25 on each side of the release housing 21 so that the safety of crossbow 100 may be operated by a right-handed or left-handed shooter. Bowstring 1 rests against the inclined surface 29 of the string horn 19 and is retained in the fully-drawn and cocked position between the string latch tangs 30 and 31 and the inclined surface 29 of the string horn 19. The load of the fully-drawn bowstring 1 is distributed between and born by the inclined the string latch tangs 30 and 31 and the inclined surface 29 of string horn 19.