Nested Segmented Pulley CVT for Wide Speed Range in Tight Spaces
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Solution Overview
Problem
Variable transmissions used in robotics and other applications face inefficiencies due to their larger and heavier design, which limits their use in space-constrained environments, and existing designs struggle to maintain minimal backlash and durability over repeated movements while accommodating a wide range of operating speeds.
Innovation Solution
A compact variable transmission design featuring a pulley system with segmented pulleys that can be nested and eccentrically orbiting, allowing for adjustable effective diameters and transmission ratios through mechanisms like hydraulic pumps and springs, reducing size and weight while maintaining efficiency and durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If variable transmissions are designed to accommodate a wide range of operating speeds, then speed adaptability is improved, but size and weight increase
Solution Approach 1:
The patent implements nesting by placing the inner pulley inside the outer pulley, with the inner pulley's orbital path contained within the outer pulley's structure. This nested configuration allows the transmission to achieve variable speed ratios through the relative motion between nested components without requiring additional space, thereby maintaining compact size while accommodating a wide range of operating speeds
Solution Approach 2:
The patent introduces eccentric orbital motion as an additional degree of freedom beyond simple rotation. The inner pulley orbits eccentrically within the outer pulley, creating variable transmission ratios through this orbital dimension. This dimensional change enables continuous speed variation without increasing the overall footprint of the transmission device
2Adaptability or versatility
If variable transmissions are designed to accommodate a wide range of operating speeds, then speed adaptability is improved, but device volume increases
Solution Approach 1:
The patent implements nesting by placing the inner pulley inside the outer pulley, with the inner pulley's orbital path contained within the outer pulley's structure. This nested configuration allows the transmission to achieve variable speed ratios through the relative motion between nested components without requiring additional space, thereby maintaining compact size while accommodating a wide range of operating speeds
Solution Approach 2:
The patent combines multiple functions into the nested pulley structure: the outer pulley provides structural support and one drive interface, while the inner pulley provides the variable ratio mechanism through orbital motion and a second drive interface. This merging of functions into a compact nested arrangement achieves variable speed capability without proportionally increasing device volume
3Measurement precision
If minimal backlash is required for robotic applications, then positioning precision is improved, but device complexity increases
Solution Approach 1:
The spring mechanism automatically adjusts to maintain optimal tension between the belt and pulleys during orbital motion, and the hydraulic system self-regulates to control the inner pulley's orbital path. This self-adjusting behavior minimizes backlash without requiring complex external control systems or multiple adjustment mechanisms
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
The compact design achieves efficient speed adaptation and reduced eccentricity, enabling the transmission to operate over a wide range of speeds with minimal backlash and increased durability, suitable for space-constrained applications like robotics.
Implementation Method 1
a hydraulic pump configured to adjust the distance between the first outer pulley segment and the second outer pulley segment
Implementation Method 2
a spring coupled to the first inner pulley segment and the second inner pulley segment to adjust the second variable distance between the first inner pulley segment and the second inner pulley segment in response to changes in the first variable distance
Implementation Method 3
an inner pulley, centered on a second axis, the second axis is not aligned with the first axis
Data Source
Figure 1
Figure 2A~2F
Figure 3A~3C
AI summary
A variable transmission may include a segmented pulley and a nested pulley located at least partially within the segmented pulley. The spacing between the components of the first segmented pulley may be varied to alter the transmission ratio of the variable transmission by altering the effective diameter of the segmented pulley. The nested pulley may also be a segmented pulley. In some embodiments, one of the pulleys may be rotationally fixed, and the variable transmission may comprise a compact infinitely variable transmission. The eccentricity of the compact infinitely variable transmission may be significantly less than the eccentricity of other infinitely variable transmission designs. In other embodiments, a nested pulley structure may be used to provide a compact continuously variable transmission.