Crossbow Accessory Trigger Assembly for Rifle Lower Receiver
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Solution Overview
Problem
Hunters accustomed to rifles find crossbows complex and difficult to operate due to heavy weight and complex trigger mechanisms, which decreases accuracy and comfort in use.
Innovation Solution
A crossbow accessory that couples with a modular rifle's lower receiver, using a trigger assembly to fire the crossbow, featuring a rigid riser, flexible limbs, pulleys/cams, and a string retractor system to reduce trigger pull force and enhance ease of operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a crossbow uses a complex trigger mechanism to hold the bowstring in firing position, then the crossbow can maintain reliability in holding the bowstring, but the trigger pull force becomes excessive and decreases accuracy
Solution Approach 1:
The patent introduces a trigger assembly as an intermediary component between the user's finger and the bowstring release. This trigger assembly acts as a mediator that translates minimal finger pressure into sufficient force to release the bowstring, while also providing the necessary reliability to hold the bowstring in position during the draw. The trigger assembly serves as the intermediary that resolves the contradiction between maintaining reliability and reducing pull force.
Solution Approach 2:
The crossbow system is segmented into distinct functional components: the trigger assembly for firing control, the string retractor for bowstring management, the pulleys/cams for mechanical advantage, and the riser/limbs for structural support. This segmentation allows each component to be optimized independently - the trigger assembly for reliability with low pull force, the string retractor for ease of operation, and the pulleys for mechanical advantage - thereby resolving the overall system contradiction.
2Reliability
If a crossbow includes complex trigger mechanisms and bowstring retraction systems, then the crossbow can achieve reliable firing and string retraction, but the weight increases making it difficult to carry and operate quickly
Solution Approach 1:
The trigger assembly is designed to serve multiple functions: it acts as the firing mechanism, provides trigger pull force reduction, and integrates with the string retraction system. The pulleys/cams simultaneously provide mechanical advantage for string retraction and serve as attachment points for the string. This multi-functionality reduces the need for separate dedicated components, thereby reducing overall weight while maintaining reliability.
Solution Approach 2:
The patent merges the trigger mechanism and string retraction system into an integrated assembly. The trigger assembly is positioned to directly influence the bowstring release, and the string retractor is integrated with the pulley system. This merging of functions into a unified mechanism reduces the total number of separate components and connections, thereby reducing weight while maintaining the reliability of both firing and string retraction functions.
3Strength
If a crossbow uses a heavy design for structural strength, then the crossbow can maintain accuracy and power, but it becomes more difficult to carry and operate quickly
Solution Approach 1:
The riser and limbs are constructed using composite materials that provide high strength-to-weight ratio. This allows the crossbow to maintain the structural strength necessary for accuracy and power delivery while significantly reducing the overall weight. The composite construction enables the crossbow to be both strong enough for reliable operation and light enough for easy carrying and quick operation.
4Power
If a crossbow has high draw weight to achieve greater range and speed, then the crossbow can fire arrows with greater velocity, but the trigger pull force increases excessively
Solution Approach 1:
The trigger assembly serves as an intermediary that decouples the high draw weight from the trigger pull force. It provides a mechanical advantage system that allows the user to apply minimal finger pressure to the trigger while still being able to release the high-tension bowstring. This intermediary mechanism enables the crossbow to maintain high draw weight for power and range while keeping the trigger pull force low and manageable.
Solution Approach 2:
The patent replaces the traditional direct mechanical linkage between the trigger and bowstring with a more sophisticated mechanical system involving pulleys, cams, and a trigger assembly. This substitution of the mechanical system allows for independent control of draw weight and trigger pull force, enabling high power delivery without proportionally high trigger pressure.
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
Enables hunters to use crossbows with minimal finger pressure, independent of bowstring tension, making the crossbow lighter, more compact, and easier to operate, while maintaining accuracy and allowing quick firing sequences.
Implementation Method 1
first and second pulleys/cams are rotatably supported at the limb tips of the first and second limbs
Implementation Method 2
the force exerted by the retracted bowstring can be in the range of approximately 100 to 200 pounds
Implementation Method 3
a spring biased hammer that may be cocked into a firing position
Data Source
AI summary
A crossbow accessory for coupling to a modular lower receiver of a rifle includes an elongated frame coupled to a riser at a first end, and coupled above the lower receiver at its second end. An upper housing secured to the second end of the frame includes a rope spool and winding gears for retracting the bowstring toward a drawn position. A rope extends from the rope spool to a bowstring release for retracting the bowstring. The bowstring release is retracted into the upper housing proximate the modular lower receiver for selectively releasing the bowstring when a user pulls the trigger of the lower receiver. A method for creating a crossbow using the modular lower receiver is also disclosed.