Coin Hopper Eccentric Fixing via Shaft Fitting
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Solution Overview
Problem
Existing small coin hoppers face mechanical strength issues due to non-coaxial alignment of the rotating disk and fixing member, leading to potential fracture under repeated rotation, and this is exacerbated by the need for high-strength materials which increase cost.
Innovation Solution
The coin hopper design features a fitting projecting part on the rotating shaft and a corresponding recessed part on the rotating disk, allowing eccentric fixation that reduces the rotational force on the fixing member, preventing fracture while maintaining mechanical strength without increasing cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the fixing member is disposed at an eccentric position to accommodate the through hole, then the through hole can be positioned correctly, but shear stress acts on the fixing member causing fatigue and potential fracture
Solution Approach 1:
A fitting protrusion is introduced as an intermediary element between the fixing member and the rotating disk. This protrusion fits into a corresponding recess on the rotating disk, creating a mechanical interface that transmits rotational forces away from the fixing member. The intermediary structure allows the fixing member to remain eccentric while the protrusion-recess pair handles the shear stresses, preventing fatigue and fracture of the fixing member.
2Reliability
If high-strength materials are used for the fixing member, then fracture risk is reduced, but cost increases
Solution Approach 1:
The functional requirement for high strength is extracted from the fixing member and transferred to the fitting protrusion-recess structure. The fixing member only needs to provide positional alignment and basic attachment, while the protrusion-recess pair handles the mechanical loading. This allows both components to be made from standard materials, eliminating the need for expensive high-strength materials while maintaining reliability.
3Device complexity
If the rotating disk and rotating shaft are fixed with standard screw-fixing, then the structure is simple, but the fixing member fractures due to repeated forward and backward rotation
Solution Approach 1:
The fixing structure is made dynamic through the fitting protrusion that engages with the recess. During rotation, the protrusion maintains continuous contact with the recess, providing adaptive support that accommodates the repeated forward and backward rotation. This dynamic engagement prevents fatigue accumulation in the fixing member while maintaining structural simplicity.
Data Source
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AI summary
A coin hopper capable of effectively preventing fracture of a fixing member, suppressing increase in cost, and increasing fixation strength of a rotating disk with respect to a rotating shaft even if a rotating axis of the rotating disk and an axis of the fixing member are not coaxial is provided. In a state in which a fitting projecting part formed on an end surface of a rotating shaft and a fitting recessed part formed on a back surface side of a rotating disk are fitted with each other, a rotating disk and a rotating shaft are fixed by a fixing member. The acting force in a rotating direction which works between the rotating disk and the rotating shaft when the rotating disk is rotated is received by the fitting between the fitting projecting part and the fitting recessed part.