Air Cycle Machine Bearing Cooling Control
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Solution Overview
Problem
Air cycle machines face challenges in effectively cooling their air bearings, which are crucial for efficient operation and temperature regulation, as existing solutions do not adequately address the need for efficient air sealing and cooling distribution within the system.
Innovation Solution
The design incorporates specific air seals and bearing assemblies with tailored dimensions and geometries, including angled surfaces, radiused portions, and strategically placed teeth on the shaft, to facilitate controlled airflow and cooling distribution between the air journal and thrust bearings, ensuring proper cooperation with pilots and housings to optimize air flow and cooling efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional air seals are used in air cycle machines, then the structure is simple, but the cooling efficiency of air bearings is insufficient and air leakage occurs
Solution Approach 1:
The air seal is divided into multiple segments including a first seal segment with a first seal surface and a second seal segment with a second seal surface. Each segment has specific dimensional ratios (first ratio and second ratio) that optimize sealing performance while maintaining structural simplicity. This segmentation allows independent optimization of each seal surface for its specific function.
Solution Approach 2:
Different seal segments are positioned at different locations with different dimensional characteristics. The first seal segment has a first ratio of seal surface diameter to seal width, while the second seal segment has a second ratio, allowing each location to be optimized for its specific sealing and cooling requirements rather than using a uniform design throughout.
2Productivity
If air seals with optimized dimensions are used, then air flow control improves, but manufacturing precision requirements increase
Solution Approach 1:
The invention specifies particular parameter ranges for the seal dimensions, including the first ratio and second ratio of seal surface diameter to seal width. By defining these as ratios rather than fixed dimensions, the design accommodates manufacturing tolerances while maintaining the functional relationship needed for effective air flow control and cooling.
3Temperature
If multiple seal segments are implemented, then cooling distribution improves, but device complexity increases
Solution Approach 1:
The multiple seal segments serve multiple functions simultaneously: sealing the air bearing gaps, distributing cooling air to different bearing surfaces, and controlling air flow patterns. This multi-functionality reduces the need for separate components for each function, thereby limiting the increase in overall device complexity while achieving improved temperature control.
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 enhances the cooling efficiency of air bearings by ensuring precise air flow and pressure management, minimizing air leakage and mixing, thereby maintaining optimal operating conditions for the air cycle machine's components.
Implementation Method 1
a centrifugal compressor driven by compressed air and a centrifugal turbine that lowers the temperature of the compressed air
Implementation Method 2
The shaft is supported by an air journal bearing and an air thrust bearing
Data Source
AI summary
An air cycle machine has a housing which holds a compressor section, and a turbine section having an expansion area, and a fan section disposed outside of the housing. A shaft, which attaches to and is coaxial with the compressor section, the turbine section and the fan section, is supported by an air journal bearing and an air thrust bearing. The shaft has a hollow core for porting cooling air from the air journal bearing and the air thrust bearing, and a tube that extends into said expansion area and communicates cooling air from the turbine expansion area to the thrust bearing.