Foil-Air Bearing Assembly for Low-Temperature Engine Starters
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Solution Overview
Problem
Existing air turbine starters face challenges in efficiently supporting the drive shaft with minimal friction and maintaining low temperatures in thrust bearings, leading to reduced operational life and power output.
Innovation Solution
The integration of a foil-air bearing assembly that supports the drive shaft at the forward side of the turbine member, utilizing a radial and thrust foil bearing configuration to create an air film for reduced friction and shared support with thrust bearings, thereby reducing the load on thrust bearings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional thrust bearings are used to support the drive shaft, then the drive shaft can be supported, but the thrust bearings experience high loads and temperatures that reduce operational life
Solution Approach 1:
The patent introduces a foil-air bearing assembly that uses compressed air to create a thin air film between the drive shaft and bearing surface. This pneumatic bearing system replaces traditional contact-based thrust bearings, eliminating direct mechanical contact and the associated friction and heat generation, thereby reducing thrust bearing temperatures and extending operational life
Solution Approach 2:
The invention substitutes traditional mechanical thrust bearings with a foil-air bearing system that relies on aerodynamic principles rather than direct mechanical contact. The air film acts as a non-contact lubricant, replacing the need for solid lubricants and reducing the mechanical stress and thermal load on bearing components
2Reliability
If traditional bearings with lubrication are used, then friction can be reduced, but lubrication requirements increase device complexity and maintenance needs
Solution Approach 1:
The foil-air bearing system is self-lubricating through the use of compressed air, which is already available in the pneumatic starter system. The air film automatically forms between the bearing surfaces without requiring external lubrication systems, seals, or maintenance, making the system self-sufficient and reducing overall device complexity
Solution Approach 2:
The system utilizes the existing compressed air supply to create the lubricating air film, turning a readily available resource into a functional lubricant. This eliminates the need for separate lubrication systems, oil reservoirs, pumps, and associated maintenance procedures
3Power
If larger starters are used to provide sufficient power output, then power requirements can be met, but the size and weight of the starter increase
Solution Approach 1:
By replacing traditional friction-based bearings with foil-air bearings, the system eliminates mechanical friction losses that would otherwise require additional power input. This efficiency gain allows for a more compact and lighter starter design while maintaining the required power output for engine starting
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 configuration results in lower thrust bearing loads and temperatures, extending operational life, enabling faster rotation and increased power output, while also reducing the need for lubrication and allowing the use of smaller starters for larger engines.
Implementation Method 1
a foil-air bearing assembly configured to rotatably support the drive shaft at a forward side of the turbine member
Data Source
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AI summary
An air turbine starter (10) that includes a turbine member (50) for rotatably extracting mechanical power from a flow of fluid (36), where the turbine member (50) is coupled to a drive shaft (60) to provide a rotational output. The air turbine starter (10) further includes a foil-air bearing assembly (70) and a thrust bearing (64) that rotatably support the drive shaft (60).