Slotted Bow Limb Structure for Reduced Full-Draw Force
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Solution Overview
Problem
Traditional bows require high draw forces and lack a let-off mechanism similar to compound bows, leading to increased weight, cost, and complexity.
Innovation Solution
The design incorporates a longitudinal slot in the limb members that allows the bowstring to pass through, with limb members that coil and uncoil during draw, achieving a peak draw force at an intermediate position followed by a lower holding force at maximum draw, mimicking a compound bow's force-draw curve.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If traditional bows use additional curvature in limbs to increase power, then power transferred to arrow is improved, but draw force required increases
Solution Approach 1:
The bowstring is routed through longitudinal slots in the limbs rather than wrapping around fixed recurve tips, allowing the string to dynamically shift its path during the draw cycle. This dynamic routing enables the bow to achieve a compound-like force-draw curve where peak force occurs at intermediate draw position followed by let-off, improving power transfer while reducing holding force at full draw
Solution Approach 2:
The invention changes the geometric parameters of the limb-bowstring interaction by introducing longitudinal slots that allow the bowstring to move relative to the limbs. This parameter change transforms the force-draw characteristics from a continuously increasing curve to one with a peak followed by reduction, achieving both high power transfer and reduced draw force requirements
2Force
If compound bows use pulleys, cams, and strings to reduce draw force, then draw force at full draw is reduced, but weight and complexity increase
Solution Approach 1:
The invention extracts the essential let-off function from complex compound bow mechanisms (pulleys, cams, multiple strings) and implements it through a simple geometric modification: longitudinal slots in the limbs. This extraction achieves the force reduction effect without the weight and complexity of mechanical advantage systems
Solution Approach 2:
The invention copies the force-draw curve characteristic of compound bows (peak force followed by let-off) using a fundamentally different mechanism. Instead of using cams and pulleys to create the curve, it uses the dynamic interaction between the bowstring and longitudinal slots to naturally produce the same force profile, achieving the effect without the complexity
3Power
If traditional bows require high draw force to be held at maximum draw, then power transfer is sufficient, but archer fatigue increases
Solution Approach 1:
The dynamic bowstring routing through longitudinal slots creates a natural let-off effect where the holding force at full draw is reduced after peak force is reached. This dynamic force reduction decreases archer fatigue while maintaining sufficient power transfer, as the bow holds at a lower force level after the initial draw
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 the draw force at full draw, allowing comfortable arrow release with efficient energy transfer, without the additional weight and complexity of modern bows.
Implementation Method 1
limb members that coil and uncoil during draw, achieving a peak draw force at an intermediate position followed by a lower holding force at maximum draw
Data Source
AI summary
A traditional bow, includes a riser with an upper and lower end. A first limb member provided at the upper end of the riser, the first limb member includes a first and second body with co-planar surfaces and proximal and distal ends. the proximal ends of the first limb member are coupled to the upper end of the riser. A first tip couples the distal ends of the first and second bodies and includes a first notch extending radially from the first tip. A first longitudinal slot extends between the first and second bodies at least partially between the upper end of the riser and the first tip. A second limb member provided at the lower end of the riser, the second limb member includes a third and fourth body with co-planar surfaces and proximal and a distal ends, the proximal ends of the second limb member are coupled to the lower end of the riser. A second tip couples the distal ends of the third and fourth bodies and includes a second notch extending radially from the second tip. A second longitudinal slot extends between the third and fourth bodies at least partially between the lower end of the riser and the second tip. A bowstring is operatively coupled between the first limb notch and second limb notch and passes through the first and second longitudinal slots. The first and second limb notches pass through three or more states as the bowstring is drawn from an initial resting position to a maximum draw length. The first and second notches being furthest apart at a first state. closest together in an intermediate state, and at a position between the furthest and closest position in a final state. A peak draw force occurs at an intermediate draw length and a reduced draw force occurs at a maximum draw length.