Selectorized Dumbbell with Thin Connecting Walls

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Solution Overview

Problem

Existing selectorized dumbbells face manufacturing costs due to robust rail requirements and user difficulties in inserting the connecting pin, along with an undesirable change in center of gravity as more weights are added, affecting usability and weight distribution.

Innovation Solution

The design features box-shaped weights with thin, planar connecting walls that are nested and stacked, allowing for easier weight adjustment with cuff link or zip lock selectors, maintaining a consistent center of gravity and reducing manufacturing costs by using thinner materials.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If robust steel rails of at least 1/4 inch diameter are used to carry spaced weight plates, then the structural strength and durability are improved, but the manufacturing cost increases and the device complexity increases

Engineering Contradiction:

Improvestructural strengthVSAvoidmanufacturing cost

Core Design Contradiction:

StrengthVSEase of manufacture

Solution Approach 1:

The patent replaces thick robust rails with thin connecting walls that are substantially imperforate and extend substantially over a full height of the weight plates. These thin walls are joined to the weight plates by welding at each end, creating a structurally sufficient connection without requiring bulky steel bar stock. This reduction in material thickness directly lowers manufacturing cost while maintaining the necessary structural strength for the application.

Inventive Principle:

Principle #30Flexible shells and thin films

Solution Approach 2:

The patent divides the weight structure into separate components: weight plates and connecting walls. The connecting walls are discrete elements that can be independently manufactured and then joined to the weight plates through welding. This segmentation allows for more efficient manufacturing processes and reduces the overall material requirements compared to monolithic rail structures.

Inventive Principle:

Principle #1Segmentation

2Reliability

If four welds are required when manufacturing each weight (two for front rail and two for rear rail), then the structural reliability is improved, but the manufacturing time and complexity increase

Engineering Contradiction:

Improvestructural reliabilityVSAvoidmanufacturing efficiency

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The thin connecting walls, while requiring welds at both ends, provide sufficient structural reliability due to their full-height extension and imperforate design. The reduced thickness and simplified geometry of these walls compared to traditional rails may actually reduce the total welding time and complexity, despite the increased number of weld locations.

Inventive Principle:

Principle #30Flexible shells and thin films

3Stability of the object's composition

If the connecting pin insertion space is located at the bottom beneath the lowermost rails, then the weight distribution is improved, but the ease of operation deteriorates due to difficult insertion

Engineering Contradiction:

Improveweight distributionVSAvoidease of pin insertion

Core Design Contradiction:

Stability of the object's compositionVSEase of operation

Solution Approach 1:

The patent inverts the conventional location of the pin insertion space by positioning it at the top of the weight structure rather than at the bottom. The selector mechanism engages with the top surface of the weight plates, allowing the connecting pin to be inserted from the top side. This inversion maintains proper weight distribution while dramatically improving ease of operation, as top insertion provides better access, alignment, and operational ergonomics compared to bottom insertion.

Inventive Principle:

Principle #13The other way round (Inversion)

4Ease of manufacture

If the rails are made thinner to reduce manufacturing cost, then the manufacturing cost decreases, but the structural strength may be compromised

Engineering Contradiction:

Improvemanufacturing costVSAvoidstructural strength

Core Design Contradiction:

Ease of manufactureVSStrength

Solution Approach 1:

The patent employs thin connecting walls that are substantially imperforate and extend substantially over the full height of the weight plates. These thin walls are strategically positioned and welded to provide sufficient structural strength for carrying the weight plates, demonstrating that reduced thickness does not necessarily compromise strength when the geometry and placement are optimized for the specific load requirements.

Inventive Principle:

Principle #30Flexible shells and thin films

Data Source

PatentUS9138611B2Selectorized dumbbell having an upper selector and weights formed by laterally spaced weight plates joined by thin connecting walls

Publication Date: 2015.09.22 POWERBLOCK HOLDINGS INC

AI summary

A selectorized dumbbell has a plurality of nested weights which each have a box-shaped configuration comprising spaced left and right weight plates joined by planar, substantially imperforate, front and rear walls. The front and rear walls of the nested weights are very thin in comparison to the weight plates, extend over substantially the full height of the weight plates, and are joined to the weight plates along substantially their entire height. A selector comprises a pair of connecting members that coact between a handle of the dumbbell and upper portions of the front and rear walls of the nested weights to select a desired number of the weights for use with the handle depending upon the selected positions of the connecting members.