Segmented Pulley Stack and Cam-Roller Shift for Slack-Free Ratio Changes
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Solution Overview
Problem
Current synchronized, segmentally interchanging pulley transmission systems face challenges in efficiently transitioning the engagement of an endless member between pulley segments without introducing interference or slack, which affects the continuous adaptation of transmission ratio and power delivery.
Innovation Solution
The system employs a key pulley segment with shortened or trimmed teeth and adjacent elongated pulley segments to maintain roundness, along with a unified stack of pulley segments and a cam-roller mechanism for precise axial movement, utilizing electromagnets for actuation to ensure seamless engagement and disengagement of pulley segments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If pulley segments are moved axially into and out of the path of the endless member to change engagement, then transmission ratio adaptation is achieved, but interference or slack occurs during transition affecting continuous power delivery
Solution Approach 1:
The pulley is divided into multiple axially displaceable segments that can independently engage or disengage from the endless member. Each segment can be positioned to maintain continuous engagement, preventing slack and interference during transmission ratio changes.
Solution Approach 2:
The elongated adjacent pulley segment is positioned in advance to bridge the gap when a key pulley segment disengages. This preliminary positioning ensures that the endless member remains continuously engaged with at least one pulley segment throughout the transition.
2Ease of operation
If key pulley segment teeth are shortened or trimmed to define angular relationship with smaller pulleys, then seamless engagement is enabled, but manufacturing complexity increases
Solution Approach 1:
Only specific key pulley segments have shortened or trimmed teeth, while other segments maintain full teeth. This localized modification creates the necessary angular relationship for seamless engagement without requiring all segments to be differently manufactured.
Solution Approach 2:
The key pulley segments feature asymmetric tooth configurations (shortened or trimmed) compared to standard segments. This asymmetry enables the angular relationship definition that allows one key pulley segment to engage while the endless member is still engaging a smaller diameter pulley.
3Reliability
If elongated adjacent pulley segments are used to maintain roundness, then engagement continuity is improved, but device complexity increases
Solution Approach 1:
The adjacent pulley segment is designed with elongated teeth that can dynamically adapt their engagement state. The elongated portion can engage the endless member when needed to maintain continuity, while remaining passive when not required, reducing the need for additional active control 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
This configuration allows for continuous engagement and disengagement of the endless member with pulley segments without interference or slack, maintaining power delivery and adapting transmission ratios efficiently, even under load, thereby enhancing the performance of mechatronic variable speed drives.
Implementation Method 1
utilizing electromagnets for actuation to ensure seamless engagement and disengagement of pulley segments
Data Source
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AI summary
A key pulley segment in a synchronized, segmentally interchanging pulley transmission system is either first or last in a pulley segment set to engage an endless member. The first or last key segment teeth to engage or disengage, respectively, are shortened or completely trimmed, and the adjacent pulley segment to the key segment is elongated such that the inward portion of the tooth profile extends toward the key segment. Shortened tooth or teeth and an elongated adjacent segment together allow for many pulley segments to be designed as key segments. Completely trimmed teeth may be engineered to create a supporting surface for the endless member on the key segment. The elongated adjacent segment may have an extending portion which slidably mates with the supporting surface of the key segment, thereby receiving radial support therefrom. Multiple pulley segments from different pulley segment sets may be connected or constructed to move together in a unified stack, and may be staggered such that any one segment may be in an engaging position with the endless member when the unified stack is moved along the axis of rotation. Unified stacks may have guiding rails on both inner and outer radial surfaces, and the pulley assembly may have mating features that receive such guiding rails. Any number of the pulley segments in a unified stack may be key pulley segments. Pulley segments of a stack may be vertically separated into one or more unified stacks. Unified stacks may be moved by way of a cam or roller cam system, where each unified stack has a slidably or ratably attached roller and roller-arm. Chassis-mounted cams engage the rollers outside of the contact zone, rollers and roller-arms are moved into and out of engagement with the cams, and individual segments of a unified stack are moved into or out of engagement. Rollers may be actuated into and out of engagement by electromagnets, fixably mounted in an array. Rollers may discretely engage with multiple cams, by way of several electromagnet-arrays, and thereby complete several stack axial motions. Electromagnets in an array may be selectively energized to move selected rollers to an active position in order to effect key pulley segment engagement, stack axial movement and transition.