Flexible Coupling Free Spin Prevention Mechanism
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Solution Overview
Problem
Flexible couplings fail to prevent free spin of the driven hub in the event of shearing or tearing of the flexible insert, leading to potential damage, especially in applications like elevators where misalignment or overload occurs.
Innovation Solution
A flexible coupling design featuring a first hub, a flexible insert with exterior and interior lobes, and a retainer component with radially arrayed openings and teeth that engage in case of insert failure, preventing free spin by ensuring the driven hub remains locked during normal operation and in case of shearing or tearing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a metal band with pins and axial grooves is used to retain the flexible belt, then the coupling can be assembled and disassembled easily, but the metal band will walk-off the belt when shafts are grossly misaligned, causing the coupling to come apart
Solution Approach 1:
The retainer component is divided into a metal band and a separate flexible insert with lobes. The flexible insert segments the retention function, allowing the lobes to engage with corresponding lobes on the metal band, providing positive retention that prevents walking off while maintaining ease of assembly and disassembly.
Solution Approach 2:
The coupling combines a metal band with a flexible plastic insert component. This composite structure integrates the rigidity and retention capability of metal with the flexibility and compliance of plastic, enabling the retainer to maintain position under misalignment while remaining easy to assemble and disassemble.
2Adaptability or versatility
If the flexible insert is designed to be flexible and resilient to accommodate misalignment, then the coupling can handle shaft alignment problems, but the driven hub will go into free spin mode if the insert shears or tears
Solution Approach 1:
The retainer component is pre-configured with radially arrayed openings and the flexible insert is pre-configured with lobes that engage with these openings. This preliminary configuration ensures that if the flexible insert fails, the lobes will automatically engage with the radially arrayed openings to prevent free spin, without requiring any additional action or detection system.
Solution Approach 2:
The design incorporates a backup retention mechanism (radially arrayed openings engaging with lobes) that is prepared in advance to cushion against the harmful effect of insert failure. This preliminary cushioning prevents the driven hub from entering free spin mode when the flexible insert shears or tears.
3Ease of operation
If a circumferential groove is used to lock the retainer band pin, then the pin can be rotated into place, but the groove is relatively short and may not provide sufficient retention under extreme conditions
Solution Approach 1:
The design transitions from a two-dimensional circumferential groove to a three-dimensional lobe engagement system. The radially arrayed openings with lobes provide retention in both the radial and axial dimensions, creating a more robust locking mechanism that prevents retainer band displacement under extreme misalignment conditions while still allowing easy pin positioning.
Data Source
AI summary
A flexible coupling includes a first hub, a flexible insert having a plurality of exterior lobes and a plurality of interior lobes, a retainer having an interior which engages the exterior lobes of the flexible insert, and a second hub having an exterior surface contoured to engage the interior lobes of the flexible insert. Protruding teeth are formed on wings of the second hub and positioned to engage sidewalls of openings formed in an inner lip of the retainer in the event that the flexible insert tears or shears, thereby preventing the second hub from going into a potentially damaging free spin mode.