Center-pivot limbs for archery bow
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Solution Overview
Problem
End-pivot limbs in archery bows experience localized forces and stresses that are magnified by the lever arm, leading to inefficient energy storage and release, as well as increased vibrations and recoil.
Innovation Solution
The design incorporates center-pivot limbs with pivot points positioned between two other pivot points along the limb's length, reducing localized stresses and increasing effective stiffness-to-mass ratio, achieved through a configuration of elongated riser, coupling members, and bow limbs with pulley members and cam assemblies that distribute forces more evenly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If end-pivot limbs are used in archery bows, then the bow can be manufactured with traditional design, but localized forces and stresses are magnified by the lever arm leading to inefficient energy storage and increased vibrations
Solution Approach 1:
The patent inverts the traditional end-pivot configuration by placing the pivot point at the center of the limb instead of at the end. This inversion moves the pivot point from the extremity to the center, fundamentally changing the lever arm geometry and reducing the magnification of localized forces and stresses, thereby improving energy storage efficiency.
Solution Approach 2:
The patent changes the critical parameter of pivot point location from the traditional end position to the center position. This parameter change fundamentally alters the mechanical advantage and stress distribution characteristics of the limb, reducing the lever arm effect and improving energy storage efficiency while maintaining structural integrity.
2Loss of energy
If end-pivot limbs are used, then the structure is simpler, but bending moment and effective moment of inertia are largest leading to energy wastage as kinetic energy
Solution Approach 1:
By inverting the pivot location from end to center, the patent reduces the bending moment and effective moment of inertia. This inversion changes the rotational dynamics of the limb, reducing the energy wasted as kinetic energy during the shooting cycle while maintaining the necessary structural strength.
3Object-affected harmful factors
If end-pivot limbs are used, then manufacturing is traditional, but localized forces and stresses are magnified leading to increased vibrations and recoil
Solution Approach 1:
The patent changes the pivot point location parameter from end to center, which fundamentally alters the stress distribution pattern. This parameter change reduces the magnification of localized forces and stresses, thereby reducing vibrations and recoil without compromising the structural integrity of the limb.
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
This design reduces bending moment and effective moment of inertia, minimizing energy wastage as kinetic energy and reducing vibrations, while maintaining energy storage efficiency and improving the bow's stability during firing.
Implementation Method 1
the limbs are deformed as the energy expended in drawing the bow is stored as strain energy of the deformed limbs. This energy is then released as kinetic energy of the arrow when the bow is shot and the limbs return to their original, unstrained shape.
Data Source
AI summary
An archery bow comprises an elongated riser, two coupling members, and two bow limbs. The riser has a pair of distal pivotable connection points, a pair of proximal pivotable connection points between the distal connection points, and a central handle portion between the proximal connection points. Each coupling member is pivotably connected at a first pivotable connection point thereof to the riser at a corresponding proximal connection point thereof. Each bow limb is pivotably connected to the riser at a corresponding distal pivotable connection point thereof and pivotably connected to a corresponding coupling member at a second pivotable connection point thereof. Each bow limb is adapted at a pulley pivotable connection point thereof to receive a pulley member pivotably connected thereto.