Adjustable Dumbbell Screw Rod Mechanism for Stable Weight Selection
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Solution Overview
Problem
Existing adjustable dumbbells require complex mechanisms and have limitations in stability and weight distribution, leading to potential interference and reduced durability due to off-centered rod engagement and smaller diameter rods.
Innovation Solution
A weight lifting system with a handle unit and screw rods of opposite threads, where the handle bar rotates to control screw rod extension or retraction, engaging weight discs through central holes, providing a simpler and more stable mechanism with fewer moving parts and larger diameter rods for enhanced stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If rack-and-pinion mechanisms are used for weight selection, then weight adjustment convenience is improved, but device complexity and durability are worsened due to multiple moving parts and off-centered rod engagement
Solution Approach 1:
The patent extracts and eliminates the complex rack-and-pinion mechanism from the dumbbell design. Instead, it uses a simple pin insertion system where pins are directly inserted into holes on the weight plates to select weights, removing unnecessary moving parts while maintaining ease of operation.
Solution Approach 2:
Rather than using a mechanism that converts rotational motion to linear motion (rack-and-pinion), the patent inverts the approach by using direct linear insertion of pins into holes. This reverses the conventional mechanism design, achieving weight selection through a simpler direct-action system.
2Ease of manufacture
If off-centered rod engagement is used, then weight plate connection is achieved, but stability and weight distribution are worsened
Solution Approach 1:
The patent uses asymmetric hole positioning on the weight plates, with holes located at specific offset positions that accommodate the pin insertion system. This asymmetric design enables proper connection while maintaining balanced weight distribution through careful positioning.
Solution Approach 2:
The patent employs identical pin-and-hole configurations on both sides of the dumbbell, creating symmetric copying of the connection mechanism. This ensures balanced weight distribution while maintaining the simplicity of the pin insertion system.
3Device complexity
If smaller diameter rods are used, then device complexity is reduced, but stability and durability are worsened
Solution Approach 1:
The patent changes the critical parameter of rod diameter to a larger size, which enhances durability and stability. The larger diameter pins provide greater strength and reliability while maintaining the simplicity of the direct insertion system, avoiding the need for complex mechanisms that would use smaller rods.
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 solution offers improved stability and reliability by ensuring balanced weight distribution, allowing for larger diameter rods and fewer parts, resulting in a more efficient and durable adjustable dumbbell design.
Implementation Method 1
two screw rods disposed through holes in the two head units into hollow sections at the two end sections of the handle bar, wherein the two screw rods have threads of opposite directions
Data Source
AI summary
A weight lifting system includes a handle unit having a handle bar, two head units attached to two end sections of the handle bar in a manner that allows the two head units to rotate about a longitudinal axis of the handle bar, two screw rods disposed through holes in the two head units into hollow sections in the handle bar, wherein the two screw rods have threads of opposite directions, two thread-engaging mechanisms fixedly disposed at the two end sections of the handle bar to fit snugly on the threads of the two screw rods, and a lock mechanism disposed in a head unit for controlling rotation of the handle bar; and a plurality pairs of weight discs, wherein each of the weight discs has a center hole configured to accommodate one of the two screw rods.