Reference Tube Spline Lubrication for Long Gas Turbine Shafts
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Solution Overview
Problem
In gas turbine engines, the length of the low-pressure shaft can prevent oil from reaching the spline for lubrication, especially when the shaft is too long, necessitating an alternative method to ensure proper lubrication for spline operation.
Innovation Solution
A reference tube circumferentially extending around the shaft with apertures allows oil to be injected from outside the shaft, passing through the tube and shaft apertures to reach the spline, creating a flow path that ensures effective lubrication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the shaft length is increased to transmit torque over longer distances, then the power transmission capability is improved, but the ability of internal oil injection to reach the spline for lubrication deteriorates
Solution Approach 1:
A reference tube is introduced as an intermediary component to deliver oil to the spline. The reference tube extends from the oil injection source toward the spline, with its tip positioned near the spline to provide direct lubrication despite the long shaft length. This mediator overcomes the limitation of internal oil injection in long shaft configurations.
Solution Approach 2:
The oil delivery system transitions from a purely internal axial injection path to a multi-dimensional approach using the reference tube that extends radially and axially to reach the spline. The tube aperture positioned near the spline end provides oil delivery in a different spatial dimension, bypassing the limitation of internal injection distance.
2Device complexity
If oil is injected through internal apertures in the shaft, then the lubrication system is simple, but the oil cannot reach the spline when the shaft is too long
Solution Approach 1:
The reference tube serves as an intermediary oil delivery conduit that extends beyond the internal shaft structure. It bridges the gap between the oil injection source and the distant spline, enabling lubrication in long shaft applications without requiring complete redesign of the internal injection system.
Solution Approach 2:
The oil delivery function is segmented into two parts: the internal shaft apertures for initial oil introduction and the external reference tube for extended delivery to the spline. This segmentation allows each component to perform its specific function optimally while working together to solve the long-distance lubrication problem.
3Stability of the object's composition
If the reference tube is secured to the shaft for rotation therewith, then the tube rotates with the shaft to maintain alignment with the spline, but the second end must be free relative to the shaft to measure deformation
Solution Approach 1:
The reference tube is segmented into two functional zones: the first end secured to the shaft for rotation therewith (maintaining rotational alignment), and the second end free relative to the shaft (enabling deformation measurement). This segmentation allows both rotational stability and measurement flexibility to coexist.
Solution Approach 2:
The reference tube serves multiple functions simultaneously: it acts as an oil delivery conduit, rotates with the shaft to maintain alignment with the spline, and its free end enables deformation measurement. This multi-functionality resolves the apparent contradiction between rotational coupling and measurement freedom.
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
This solution enables efficient lubrication of the spline by directing oil through the reference tube and shaft apertures, ensuring the spline receives the necessary lubrication even when the shaft is too long for internal oil injection, thereby maintaining proper engine operation.
Implementation Method 1
an oil nozzle fluidly connected to a source of lubricant, the oil nozzle defining an exit flow axis intersecting the at least one tube aperture for injecting oil through the reference tube
Implementation Method 2
a reference tube circumferentially extending around the shaft, the reference tube secured at a first end to the shaft for rotation therewith and a second end free relative to the shaft for measuring a deformation of the shaft
Data Source
AI summary
A gas turbine engine, has: a shaft rotatable about a central axis and engaged at an end thereof to a rotatable load via a spline; a reference tube circumferentially extending around the shaft, the reference tube secured at a first end to the shaft for rotation therewith and a second end free relative to the shaft for measuring a deformation of the shaft, the reference tube defining at least one tube aperture therethrough; an oil nozzle fluidly connected to a source of lubricant, the oil nozzle defining an exit flow axis intersecting the at least one tube aperture for injecting oil through the reference tube, the shaft defining at least one shaft aperture extending therethrough, the oil nozzle aligned with the spline via the at least one tube aperture and the at least one shaft aperture.