Variable Stator Vane Mounting Arrangement
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Solution Overview
Problem
The existing mounting arrangements for variable stator vanes in gas turbine engines are time-consuming and costly due to the machining of bores and fitting of polymeric bushings in the inner shroud.
Innovation Solution
A mounting arrangement featuring an inner shroud with a radially- and circumferentially-extending slot and inserts formed of reinforced plastics material, where the inserts are retained within the slot, eliminating the need for drilling and allowing for injection moulding, thereby reducing manufacturing time and costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If machined/drilled bores with polymeric bushings are used in the inner shroud, then the variable stator vane can be properly mounted and supported, but the manufacturing time and cost increase
Solution Approach 1:
The patent combines the bushing and the inner shroud into a single integrated component. The polymeric bushing is molded directly into the inner shroud as a unified piece, eliminating the separate drilling and fitting operations. This merging of components resolves the contradiction by maintaining the mounting reliability of the bushing while dramatically reducing manufacturing time through a single molding process.
Solution Approach 2:
The patent uses composite materials by integrating the polymeric bushing material with the inner shroud material in a single molded component. This composite approach allows the bushing to be formed as an integral part of the shroud, achieving both the functional requirements of the bushing (reducing wear and allowing thermal expansion) and the manufacturing efficiency of a single-piece construction.
2Reliability
If machined/drilled bores with polymeric bushings are used in the inner shroud, then the variable stator vane can be properly mounted and supported, but the manufacturing cost increases
Solution Approach 1:
The patent combines the bushing and the inner shroud into a single integrated component. The polymeric bushing is molded directly into the inner shroud as a unified piece, eliminating the separate drilling and fitting operations. This merging of components resolves the contradiction by maintaining the mounting reliability of the bushing while dramatically reducing manufacturing time through a single molding process.
Solution Approach 2:
The inner shroud is designed to be self-forming the bushing through the molding process itself. The molding cavity includes features that automatically create the bushing geometry and integration features during the standard shroud molding operation, eliminating the need for separate bushing installation operations and reducing overall manufacturing complexity and cost.
3Stability of the object's composition
If the insert has a greater axial width than the slot to provide secure retention, then the insert cannot move past the slot width, but the manufacturing complexity increases due to the smooth transition requirement
Solution Approach 1:
The patent uses curved surfaces and smooth transitions in the geometric profile of both the slot and the insert. The gradual change in width from the base to the top of the slot and insert creates a smooth, curved transition zone that facilitates manufacturing while maintaining the retention function. This curved geometry resolves the contradiction by providing secure retention through the width difference while keeping the manufacturing process simple through smooth, continuous surfaces.
Data Source
AI summary
The present invention provides a mounting arrangement for mounting a variable stator vane within a gas turbine engine. The mounting arrangement comprises an inner shroud having a radially- and circumferentially-extending slot and at least one insert which, in use, is retained within said slot. The or each insert has at least one bore for receiving a spindle portion of the variable stator vane. The at least one insert is formed of a plastics material and/or the slot and the at least one insert each have a respective axial cross section with a respective first width (axial dimension) which is greater than and radially inwards from a respective second width, the first width of the at least one insert being greater than the second width of the slot and there being a smooth transition between the respective first and second widths.