Symmetrical Resistance Pulley Structure for Uniform Rowing Load
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Solution Overview
Problem
Existing resistance components, such as stay cord mechanisms in fitness equipment, suffer from low tensile strength, uneven stress distribution, and limited adjustability, leading to instability and inefficiency in providing resistance.
Innovation Solution
A resistance pulley structure featuring symmetrical stay cord assemblies with multiple fixed and movable pulleys, transmission belts, and magnetic resistance assemblies, allowing for adjustable and uniform force distribution, and a rowing machine integrating this structure for versatile training modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a single stay cord and fixed pulley are used to form resistance, then the structure is simple, but the tensile strength is low and stress is uneven
Solution Approach 1:
The single stay cord system is segmented into multiple stay cords (first stay cord and second stay cord) that work in parallel. Each stay cord is routed through separate pulleys (first fixed pulley, second fixed pulley, first movable pulley, second movable pulley) to distribute the load and increase overall tensile strength while maintaining manageable complexity through modular arrangement
Solution Approach 2:
The system transitions from a single-dimension linear pull to a multi-dimensional routing configuration. The stay cords are routed through pulleys arranged in space to create multiple force vectors that converge on the movable pulley block, increasing tensile strength through spatial distribution of forces
2Stability of the object's composition
If a single stay cord and fixed pulley are used to form resistance, then the structure is simple, but the stress distribution is uneven
Solution Approach 1:
The resistance system is segmented into multiple identical stay cord-pulley units (first unit and second unit) that are symmetrically arranged. This segmentation ensures that the total load is divided into equal portions carried by each unit, achieving uniform stress distribution across all components
Solution Approach 2:
The system uses symmetrical arrangement of components (mirror-image configuration of first and second stay cords, pulleys, and routing paths) to ensure balanced force distribution. The symmetry creates equivalent mechanical advantage ratios for both sides, preventing uneven stress concentration
3Adaptability or versatility
If magnetic resistance assemblies are added to provide adjustable resistance, then the resistance strength is adjustable, but the device complexity increases
Solution Approach 1:
The traditional mechanical friction-based resistance system is replaced with a magnetic resistance system. Magnetic fields provide resistance force without physical contact or mechanical wear, allowing for smooth, stepless adjustment of resistance levels through electromagnetic control while reducing mechanical complexity
Solution Approach 2:
The resistance level is adjusted by changing magnetic field parameters (strength, polarity, or positioning) rather than mechanical parameters. This allows continuous, precise control of resistance force independent of the mechanical structure, enhancing adaptability without proportionally increasing structural complexity
4Reliability
If multiple pulleys and transmission assemblies are used to enhance tensile strength, then the stability is improved, but the device complexity increases
Solution Approach 1:
The transmission system is segmented into multiple independent but coordinated pulley units. Each pulley unit (fixed and movable) operates as a reliable module, and the system achieves enhanced stability through the combined action of these segmented units distributed across the mechanical structure
Solution Approach 2:
The force transmission is extended into multiple spatial dimensions through the arrangement of pulleys at different positions and orientations. This multi-dimensional routing creates redundant force paths that enhance system stability and reliability while distributing mechanical stress across a larger structural volume
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
Enhances tensile strength, stability, and adjustability, enabling efficient and safe dual-mode training with a rowing machine that can switch between high-position pull-down and rowing exercises, saving space and cost.
Implementation Method 1
a first magnetic part provided on an outer periphery of the driven pulley and a second magnetic part provided outside the first magnetic part; a space is provided between the first magnetic part and the second magnetic part, and the first magnetic part and the second magnetic part cooperate to generate magnetic resistance to limit a rotation speed of the driven pulley
Data Source
AI summary
A resistance pulley structure includes a symmetrical stay cord assembly, a transmission assembly, a resistance assembly and driving parts. The stay cord assembly includes a stay cord, a first and a second fixed pulley block and a movable pulley block. The movable pulley block includes a left and right movable pulleys, and the second fixed pulley block includes a second left fixed pulley and a second right fixed pulley. The rotation direction of the second fixed pulley block is parallel to the rotation direction of the first fixed pulley. After the stay cord bypasses the first fixed pulley, two ends bypass the left and right movable pulley respectively, then bypass the second left fixed pulley and the second right fixed pulley respectively, and connected to the driving parts.