Compressor Shaft Trunnion Extraction via Segmented Lock Nut
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Solution Overview
Problem
In small-sized turbojets, the radial size constraint makes it difficult to remove the high-pressure spool module rearwards without first removing the fan module and the bevel gear, which supports the ball bearing, due to the compact assembly design.
Innovation Solution
An assembly comprising a bevel gear centered on a longitudinal axis with a compressor shaft trunnion coaxially disposed inside, a lock nut to prevent axial movement of the bevel gear, and an anti-rotation pin to prevent rotation, allowing the trunnion to be extracted rearwards without disassembling the bevel gear or fan module.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the radial size of the turbojet is reduced to create a compact assembly, then the engine size is decreased, but the difficulty of removing the high-pressure spool module rearwards increases
Solution Approach 1:
The invention divides the fastening system into separate functional elements: a lock nut for axial positioning and an anti-rotation pin for rotational constraint. This segmentation allows the trunnion to be extracted independently from the bevel gear by removing only the lock nut and anti-rotation pin, without requiring removal of the entire bevel gear assembly or fan module, thus enabling easy rearward extraction of the high-pressure spool module in compact turbojet designs
Solution Approach 2:
The invention extracts the fastening function from the bevel gear assembly itself and places it in separate removable components (lock nut and anti-rotation pin). This allows the trunnion to be extracted from the bevel gear by simply removing these fastening elements, enabling the high-pressure spool module to be removed rearwards without dismantling the bevel gear or fan module, thereby solving the extraction difficulty in compact configurations
2Volume of moving object
If the bevel gear is mounted directly on the compressor shaft trunnion to enable compact design, then the radial size is reduced, but the ease of dismounting the trunnion deteriorates
Solution Approach 1:
The fastening system is segmented into a lock nut with axial positioning features and a separate anti-rotation pin with rotational constraint features. This segmentation enables the trunnion to be easily dismounted by removing only these two small fastening components rather than the entire bevel gear assembly, significantly improving ease of repair and maintenance in compact turbojet designs
Solution Approach 2:
The lock nut acts as an intermediary element between the bevel gear and the compressor shaft trunnion, providing axial positioning and enabling extraction. The anti-rotation pin serves as another intermediary that prevents rotational movement during operation but can be easily removed to allow trunnion extraction. These intermediary fastening components enable easy dismounting while maintaining the compact direct-mounted configuration
Data Source
AI summary
The invention relates to an assembly between a compressor shaft trunnion and a bevel gear for driving an accessory gearbox of a turbomachine. The assembly comprises a bevel gear, a compressor shaft trunnion arranged coaxially inside the bevel gear, torque transmission means between the compressor shaft trunnion and the bevel gear, a lock nut for preventing the bevel gear from moving axially on the compressor shaft trunnion, the lock nut being suitable for being screwed onto the bevel gear and including a shoulder projecting radially outwards and suitable for coming into axial abutment firstly upstream against a stop nut screwed onto an upstream end of the compressor shaft trunnion, and secondly downstream against a bearing surface of the compressor shaft trunnion, and an anti-rotation pin for preventing the lock nut from rotating.