Radial Strut Connection to Circular Casing Using Pins and Spacers
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Solution Overview
Problem
The assembly of radial arms to a circular shroud in turbomachines is challenging due to limited clearance from fairings, leading to difficulties in alignment and tool access, and existing connection designs face issues with bending and shearing forces, overheating, and potential bolt seizure, making them cumbersome and prone to assembly errors.
Innovation Solution
A connection arrangement featuring radial arms with pins and spacers, where the arms have parallel holes at their ends, positioning pins extend through these holes, and spacers are placed between the pins and the outer shroud, with bolts passing through alignments to secure the assembly, reducing forces applied and ensuring precise positioning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If classic bolt connection with single ear is used, then assembly is simple, but bolt is loaded in bending requiring larger connection parts
Solution Approach 1:
The invention uses a symmetrical double-ear configuration instead of the asymmetrical single-ear design, positioning ears on opposite sides of the shroud to create a balanced connection geometry that eliminates bending moments on the bolt
2Strength
If two parallel lugs are used to reduce bending forces, then connection can be lighter, but bolt undergoes significant shearing and bending
Solution Approach 1:
The invention transitions from a planar lug arrangement to a three-dimensional configuration where ears are positioned on opposite sides of the shroud, creating a symmetrical arrangement that distributes forces evenly and eliminates bending components
3Manufacturing precision
If lugs are brought close to each other, then play with arm end becomes small, but assembly becomes difficult or impossible with inclined arms
Solution Approach 1:
The invention incorporates preliminary positioning features (ears extending beyond shroud surface, alignment holes) that guide the arm into correct position before final bolt tightening, enabling precise positioning while maintaining easy assembly access
4Object-affected harmful factors
If fairings are threaded around arms, then protection from overheating is provided, but clearance to outer shroud is reduced making assembly difficult
Solution Approach 1:
The invention segments the connection components (ears, bolts, washers) into separate assembly elements that can be introduced through the limited clearance space, with the fairing remaining as a separate protective component
Data Source
Figure 1~4
Figure 5~9
AI summary
The connection of an arm (10) to a ferrule (11) is achieved primarily by means of shafts (21) passing through the arm, spacers (26) between the shafts and the ferrule, and assembly bolts (32). Assembly and disassembly are easy, even in very confined spaces; the connection is lightweight and free of high internal stresses, and good positional accuracy is achieved. This design is applicable to stators with an outer ferrule, an inner hub, and radial connecting arms, as found in certain turbomachinery and in aeronautics.