Rotation-Proofing Peg Lug Prevents Heat Shield Wear
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Solution Overview
Problem
The existing assembly for preventing distributor segments in a turbo machine from rotating inside the casing is prone to wear, as the heat shield sheet can release from its contact with the rotation-proofing peg, causing the downstream part of the sheet to rub against the casing and create scratches.
Innovation Solution
A modified rotation-proofing peg with a lug extending at right angles to the axis is introduced, which provides an abutment surface for the heat shield sheet to bear against, preventing radial displacement and contact with the casing during operation, allowing the existing components to remain unchanged.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the heat shield sheet is used to protect the casing wall from radiant heat, then thermal protection is improved, but the sheet may release from contact with the rotation-proofing peg and cause wear on the casing
Solution Approach 1:
The patent introduces an abutment surface on the rotation-proofing peg that acts as an intermediary between the heat shield sheet and the casing. This mediator ensures the heat shield sheet remains properly positioned and prevents direct contact between the sheet and casing wall, eliminating wear while maintaining thermal protection.
Solution Approach 2:
The abutment surface is designed in advance to prevent the heat shield sheet from displacing radially outward. By providing this preventive structural feature on the peg, the system anticipates and prevents the harmful displacement before it can occur during operation.
2Reliability
If the rotation-proofing peg is modified to include an abutment surface, then reliability of heat shield positioning is improved, but device complexity increases
Solution Approach 1:
The patent applies local quality by adding only a specific abutment surface feature to the rotation-proofing peg where it is needed - at the location where the heat shield sheet contacts the peg. This localized modification improves reliability without requiring a complete redesign of the entire peg structure.
Solution Approach 2:
The rotation-proofing peg is functionally segmented into distinct features: the head portion that engages the notch, the rod portion that enters the housing, and the added abutment surface. This segmentation allows each feature to perform its specific function independently, making the design modular and easier to manufacture.
3Force
If the heat shield sheet tab bears against the rotation-proofing peg, then holding of the segment is improved, but radial displacement may occur during operation
Solution Approach 1:
The abutment surface serves as a mediator that provides a stable reference surface for the heat shield sheet tab. This intermediary feature ensures the tab maintains consistent contact with the peg while preventing radial displacement, thereby stabilizing the position without reducing the holding force.
Data Source
AI summary
A device for preventing rotation of a segment of nozzle guide vanes assembly in a form of an annulus sector housed inside an annular casing of a turbo machine with interposing of a heat shield sheet between an internal wall of the casing and an external wall of the segment of nozzle guide vanes assembly, the device including a rotation-proofing peg fitted both into a notch formed in the segment of nozzle guide vanes assembly and in a housing formed in the casing, the heat shield sheet including a tab resting against the rotation-proofing peg. A surface portion radially between the tab and the internal wall of the casing forms an end stop in event of a possible radial movement of the heat shield sheet while the turbo machine is in operation.