Adjustable Crossbow Stock for Easier Cocking

Solution Overview

Problem

High-performance crossbows with longer stocks are difficult to cock due to the increased length required for arrow propulsion speed, making it hard for users to generate the necessary force without compromising performance.

Innovation Solution

A method that involves reducing the length of the crossbow stock prior to cocking using an adjustable mechanism, allowing the bowstring to be grasped and pulled to a cocked position without compromising the crossbow's performance length.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If the stock length is increased to improve arrow propulsion speed, then the crossbow performance is improved, but the ease of cocking deteriorates

Engineering Contradiction:

Improvearrow propulsion speedVSAvoidease of cocking

Core Design Contradiction:

SpeedVSEase of operation

Solution Approach 1:

The stock length is made dynamically adjustable rather than fixed. The stock includes a telescopic mechanism with movable sections that allow the user to extend the stock for optimal arrow propulsion speed during firing, and retract the stock to a shorter length for easier cocking. This dynamic adjustment resolves the contradiction by allowing both long and short stock configurations depending on the operational phase.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The stock is divided into multiple segments or sections that can be independently positioned. The telescopic stock comprises an inner movable section and an outer fixed section, allowing the effective length to be segmented and adjusted. This segmentation enables the user to have a long stock for performance when needed, and a short stock for ease of cocking, thus resolving the technical contradiction.

Inventive Principle:

Principle #1Segmentation

2Speed

If the stock length is increased to maintain performance, then the arrow propulsion speed is maintained, but the user's ability to generate cocking force deteriorates

Engineering Contradiction:

Improvearrow propulsion speedVSAvoidcocking force generation

Core Design Contradiction:

SpeedVSForce

Solution Approach 1:

The stock length is made dynamically adjustable rather than fixed. The stock includes a telescopic mechanism with movable sections that allow the user to extend the stock for optimal arrow propulsion speed during firing, and retract the stock to a shorter length for easier cocking. This dynamic adjustment resolves the contradiction by allowing both long and short stock configurations depending on the operational phase.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The user performs the action of retracting the stock to a shorter length before the cocking action. This preliminary adjustment of stock length creates favorable conditions for the subsequent cocking operation by reducing the distance the user must reach and allowing better positioning of the body to generate cocking force, while preserving the option to extend the stock later for optimal performance.

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS7748370B1Method of cocking a crossbow having increased performance

Publication Date: 2010.07.06 HORTON ARCHERY LLC

AI summary

A crossbow (20) has a stock (21) which can be adjusted in length by utilization of an adjustment mechanism (34). In order to conveniently cock the crossbow (20) the adjustment mechanism (34) is used to shorten the length of the stock (21). But when the crossbow (20) is to be fired, the length of the stock may be increased as described by the user.