Adjustable Dumbbell Telescopic Assembly with Zero-Pitch Sections
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing adjustable dumbbells face safety hazards due to potential weight stack failure when screw shafts fail to accurately engage with weight stacks, leading to risks of weight stacks falling off, especially with thin stacks and precision errors, and this issue is costly to address through precision improvements or complex separation devices.
Innovation Solution
A telescopic assembly with toggle members and thread grooves featuring zero and non-zero thread pitch sections, allowing discontinuous movement by toggling, reduces weight stack falling risk without increasing cost, using spherical or threaded bumps to ensure smooth operation and precise engagement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the screw shaft continuously rotates to adjust weight stacks, then the weight adjustment function is achieved, but the screw shaft cannot accurately engage with thin weight stacks due to continuous rotation, causing safety hazards
Solution Approach 1:
The thread groove is designed with periodic zero-pitch sections that interrupt the continuous threading action. When the toggle bump enters a zero-pitch section, the screw shaft stops advancing even though rotation continues, creating periodic pauses that allow accurate engagement with thin weight stacks while maintaining the overall continuous rotation operation
Solution Approach 2:
The thread groove has different properties in different sections: non-zero pitch sections for normal weight stack engagement and zero pitch sections for precise positioning. This local differentiation allows the same continuous rotation mechanism to achieve both smooth operation and accurate engagement with thin weight stacks
2Reliability
If the thickness of weight stacks is increased to prevent falling off, then safety is improved, but the dumbbell becomes heavier and more complex
Solution Approach 1:
Instead of changing the physical thickness parameter of weight stacks, the invention changes the operational parameter by introducing zero-pitch sections in the thread groove. This allows thin weight stacks to be securely engaged without increasing their thickness, thereby maintaining the dumbbell's weight while improving safety
3Manufacturing precision
If precision manufacturing is increased to ensure accurate engagement, then safety is improved, but manufacturing cost increases
Solution Approach 1:
The zero-pitch sections are simple periodic interruptions in the thread groove that can be manufactured using standard machining processes. This periodic structure provides accurate engagement positions without requiring complex precision manufacturing, thereby maintaining cost-effectiveness while improving engagement precision
Solution Approach 2:
The zero-pitch sections act as intermediary positioning zones between normal threading sections. These simple geometric features provide precise engagement without requiring complex precision manufacturing, serving as cost-effective intermediaries that ensure accurate weight stack connection
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 design effectively reduces weight stack falling risks and improves safety while controlling costs by ensuring precise, discontinuous movement and smooth operation, enhancing user experience and reducing complexity.
Implementation Method 1
Thread grooves with opposite rotating directions are respectively formed in outer cylindrical surfaces of the two semi-cylindrical rods. Two toggle bumps can slide in the thread grooves of the two semi-cylindrical rods, respectively.
Data Source
AI summary
There is provided a telescopic assembly for an adjustable dumbbell, including a rotating rod and a telescopic rod. The rotating rod is a hollow round rod. The telescopic rod includes two semi-cylindrical rods split in half. The telescopic rod is inserted into the rotating rod. Toggle members are respectively arranged at two ends of the rotating rod. The toggle members are fixedly connected to the rotating rod. Toggle bumps are arranged on the toggle members. Thread grooves with opposite rotating directions are respectively formed in outer cylindrical surfaces of the two semi-cylindrical rods. Two toggle bumps can slide in the thread grooves of the two semi-cylindrical rods, respectively. The thread grooves include zero thread pitch sections and non-zero thread pitch sections. The zero thread pitch sections and the non-zero thread pitch sections are arranged in a staggered manner.