Telescopic Dumbbell Assembly With Segmented Thread Pitch Locking
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Solution Overview
Problem
Existing adjustable dumbbells face safety hazards due to potential weight stack failure when screw shafts fail to align accurately with weight stacks, leading to risks of weight stacks falling off, especially with thin stacks and precision errors, and current solutions to improve safety either require high precision or complex devices, increasing costs.
Innovation Solution
A telescopic assembly with toggle members and thread grooves featuring zero and non-zero thread pitch sections, allowing discontinuous movement of the telescopic rod, reducing the need for high precision and complex separation devices, and incorporating toggle bumps that change direction abruptly to ensure safe, discontinuous operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the screw shaft continuously stretches to connect weight stacks, then the weight adjustment function is achieved, but the weight stack may fall off due to insufficient stretching distance
Solution Approach 1:
The thread groove is segmented into multiple sections with different thread pitches: a first thread pitch section for initial connection, a second thread pitch section with larger pitch for main stretching, and a third thread pitch section for final positioning. This segmentation allows the screw shaft to achieve both easy operation and reliable connection by using different stretching rates in different stages.
Solution Approach 2:
The thread groove dynamically changes its thread pitch along the axial direction, transitioning from small pitch to large pitch and back to small pitch. This dynamic pitch variation enables the screw shaft to adapt its stretching behavior automatically during rotation, achieving both ease of operation and connection stability without additional control mechanisms.
2Reliability
If high precision is used to ensure accurate alignment between screw shaft and weight stack, then the safety is improved, but the manufacturing cost increases
Solution Approach 1:
The thread groove changes its geometric parameters (thread pitch) along the axial direction, creating zones with different stretching characteristics. This parameter variation allows standard precision manufacturing to achieve functional requirements without requiring ultra-precise alignment, as the varying pitch compensates for minor positioning errors during operation.
3Reliability
If a complex separation device is added to prevent weight stack falling, then the safety is improved, but the device complexity increases
Solution Approach 1:
The safety function is merged into the existing thread groove structure by incorporating varying thread pitch sections. This eliminates the need for separate safety devices or mechanisms, as the thread groove itself provides both the connection function and the retention safety through its geometric design.
Solution Approach 2:
The thread groove structure serves itself by using its own geometric variations to provide safety functions. The varying pitch sections automatically prevent weight stack falling without requiring external control systems or additional safety components, as the structure inherently regulates its own operation.
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 without increasing costs, ensuring smooth operation and precise weight adjustments.
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
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AI summary
The present invention relates to 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.