Gear Pump Coupling Shaft Lubrication via Radial Shoulder Slots
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Solution Overview
Problem
Fuel gear pumps for gas turbine engines face challenges in maintaining lubrication of splines to minimize wear and ensure performance throughout their service life, particularly in transferring rotational power through gear stages with varying pressures and flows.
Innovation Solution
A method of lubricating a coupling shaft in a gear pump by communicating lubricant through specifically designed slots and radial shoulders, ensuring continuous lubrication and preventing pressure buildup, while maintaining axial position and full spline engagement with mating gears.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If lubricant is communicated through slots in radial shoulders of the coupling shaft, then spline lubrication is improved and wear is minimized, but pressure buildup may occur between gear stages
Solution Approach 1:
The coupling shaft is segmented into multiple radial shoulders with slots between them, creating discrete lubrication zones. This segmentation allows lubricant to be distributed at specific locations (between splined end sections) while providing pathways for pressure relief, preventing overall pressure buildup in the system.
Solution Approach 2:
The slots in the radial shoulders act as intermediary channels that mediate between the high-pressure gear stage operations and the lubrication needs of the splines. These slots provide controlled pathways for lubricant flow and pressure equalization, preventing direct pressure transmission that would cause buildup.
2Reliability
If the coupling shaft is designed with multiple radial shoulders and slots, then lubrication distribution is improved, but the device complexity increases
Solution Approach 1:
The radial shoulders on the coupling shaft serve multiple functions simultaneously: they provide structural support for axial positioning, create mounting surfaces for splined end sections, and incorporate slots that enable lubrication distribution and pressure relief. This multi-functionality reduces the need for separate dedicated lubrication components.
Solution Approach 2:
The lubrication distribution system is merged directly into the coupling shaft structure itself, rather than being a separate system. The slots are integrated into the radial shoulders of the shaft, combining the shaft's mechanical function with the lubrication delivery function in a single component.
3Reliability
If axial position of the coupling shaft is maintained using radial shoulders, then full spline engagement is ensured, but the slots may reduce structural strength
Solution Approach 1:
The slots are positioned locally in specific regions of the radial shoulders where they provide lubrication access, rather than being distributed throughout the entire shaft. This localized approach provides necessary lubrication functionality while minimizing the impact on overall structural strength of the coupling shaft.
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 approach effectively reduces wear and maintains performance by ensuring continuous lubrication and proper spline engagement, addressing the need for efficient lubrication across the wide operating range of fuel gear pumps.
Implementation Method 1
communicating lubricant from a first gear stage along a first splined end section of the coupling shaft and through a first slot in a first radial shoulder of the coupling shaft
Data Source
AI summary
A method of lubricating a coupling shaft of a gear pump includes communicating lubricant from a first gear stage along a first splined end section of the coupling shaft and through a first slot in a first radial shoulder of the coupling shaft, and also communicating lubricant from a second gear stage along a second splined end section of the coupling shaft and through a second slot in a second radial shoulder of the coupling shaft. The first radial shoulder is axially spaced from the second radial shoulder by an axial distance SA along an axis of rotation of the coupling shaft. The first and second slots each define a lowermost radial dimension SR from the axis of rotation, with a ratio SR/SA of 0.25-0.77.