Conical Hub Joint Assembly for High-Torque Shaft Coupling
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Solution Overview
Problem
Current low moment hub joint assemblies for turbomachinery are limited by a tendency for interface surfaces to adhere during assembly and disassembly, leading to stuck parts and surface damage, which results in high repair costs and reduced machine capacity and reliability.
Innovation Solution
A hub joint assembly comprising a coupling hub and a clamp ring with a conically-shaped bore and passage for hydraulic fluid distribution, along with an anti-adhesion coating and distribution grooves, to increase the interference limit and prevent surface damage by using hydraulic pressure to frictionally couple the hub to the shaft.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If hydraulic interference fit is used to connect hub and shaft, then torque transmission capability is improved, but interface surfaces tend to adhere during assembly and disassembly leading to stuck parts and surface damage
Solution Approach 1:
A clamp ring is introduced as an intermediary component between the hub and shaft. The clamp ring includes a conically-shaped inner surface that interfaces with the hub's conically-shaped outer surface, while the hub's inner surface interfaces with the shaft. This intermediary structure allows the clamp ring to be independently expanded using hydraulic fluid to create interference fit with the hub, preventing direct adhesion between hub and shaft surfaces while maintaining torque transmission capability
Solution Approach 2:
The patent replaces direct mechanical interference fit between hub and shaft with a hydraulic expansion system. Hydraulic fluid is introduced into the clamp ring to expand it radially outward, creating controlled interference pressure against the hub's conical surface. This substitution eliminates the need for high-force mechanical pressing that causes surface adhesion and damage, while achieving equivalent or superior torque transmission
2Power
If interference limit between hub and shaft is increased to improve torque capacity, then power density is improved, but surface damage and stuck parts occur during assembly and disassembly
Solution Approach 1:
The clamp ring serves as a mediator that distributes and controls the interference pressure. By expanding the clamp ring hydraulically, high interference pressure is applied uniformly through the conical surfaces of the clamp ring and hub, achieving high torque capacity without the localized stress concentrations that cause surface damage in direct hub-shaft interference fits
Solution Approach 2:
Hydraulic fluid is used to expand the clamp ring radially outward against the hub. This hydraulic expansion mechanism provides controlled, uniform pressure distribution across the contact surfaces, enabling high interference limits to be achieved for increased power density while avoiding the shock loading and surface damage associated with traditional mechanical interference fit assembly methods
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 solution effectively increases the interference limit between the hub and shaft, reducing the risk of surface damage and enhancing the reliability and capacity of the hub joint assembly by allowing higher torque friction fit connections without sacrificing power density.
Implementation Method 1
A passage is defined in the clamp ring and extends from the outer surface of the clamp ring to the inner surface of the clamp ring. The outer surface of the clamp ring may be configured to be positioned within a bore defined in the connector.
Implementation Method 2
The inner surface of the clamp ring may be conically-shaped and configured to mate with the outer surface of the coupling hub to form an interface. The collar portion includes a bore having an inner surface that is configured to be positioned adjacent to an outer surface of the shaft
Data Source
AI summary
A hub joint assembly for frictionally connecting a shaft to a connector is provided. The hub joint assembly includes a coupling hub including a collar portion and a flange portion. The collar portion includes a bore having an inner surface that is configured to be positioned adjacent to the outer surface of the shaft. The collar portion further includes an outer surface that may be conical. The flange portion extends from the collar portion and is configured to be coupled with the connector. The hub joint assembly further includes a clamp ring including a bore having an inner surface. The inner surface may be conical and configured to mate with the outer surface of the coupling hub. A passage is defined in the clamp ring and extends from an outer surface of the clamp ring to the inner surface of the clamp ring.