Compressor Thrust Bearing Hot Air Venting
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Solution Overview
Problem
Hot air leakage from the compressor outlet past a seal in air cycle machines can flow through hydrodynamic thrust bearings, reducing their lifespan due to excessive heat exposure.
Innovation Solution
An orifice is strategically placed in the compressor housing to divert leaked hot compressed air around the hydrodynamic thrust bearings, routing it to the downstream side of the bearing, thereby preventing direct contact with the bearings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If seals are used to separate flow in the housing, then flow separation is achieved, but hot air leakage past the seal reduces thrust bearing lifespan
Solution Approach 1:
A baffle plate is introduced as an intermediary element between the seal and the thrust bearing. The baffle plate intercepts hot air that leaks past the seal and redirects it away from the bearing, preventing direct contact. This mediator resolves the contradiction by blocking the harmful flow path without compromising the seal's flow separation function.
Solution Approach 2:
The invention converts the harmful hot air leakage into a beneficial cooling flow path. By positioning the baffle plate to redirect the leaked hot air through a specific path that exits at the downstream side of the bearing, the previously harmful hot air becomes part of the controlled cooling system, actually helping to cool the bearing while preventing thermal damage.
2Temperature
If cooling flow paths are created in the housing, then bearing cooling is achieved, but hot compressed air leakage through the path reduces bearing life
Solution Approach 1:
The baffle plate serves as a mediator that separates the cooling flow path from the bearing surface. It allows cooling air to flow through the designated path while preventing hot leaked air from directly contacting the bearing, thus maintaining low bearing temperature without exposing it to harmful hot air.
Solution Approach 2:
The housing internal space is segmented into distinct flow zones using the baffle plate. The plate creates separate regions for cooling air intake, hot air leakage path, and bearing protection zone. This segmentation ensures that cooling function and protection function are spatially separated, allowing both objectives to be achieved simultaneously.
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 effectively prevents hot air from reaching the hydrodynamic thrust bearings, enhancing their lifespan and operational efficiency by creating an improved cooling path that routes leakage away from the bearings.
Implementation Method 1
An orifice is provided in the compressor housing portion whereby the orifice is arranged to route the hot compressed fluid that has leaked past the seal around the hydrodynamic thrust bearing to the downstream side of the hydrodynamic bearing
Implementation Method 2
Axial forces imparted on the shaft are counteracted by a pair of thin foil hydrodynamic thrust bearings arranged on either side of the thrust runner
Implementation Method 3
Airflow through the cooling path cools the hydrodynamic bearings
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
An air cycle machine (10) includes a housing having a compressor housing portion (70). A shaft (58) is supported by the housing and includes a thrust runner (66). A hydrodynamic thrust bearing (68) is arranged adjacent to the thrust runner (66) and includes upstream and downstream sides. A compressor rotor (65) is mounted on the shaft (58). A seal (74) is arranged between the compressor rotor and the compressor housing portion. An orifice (84) is provided in the compressor housing portion (70) at the downstream side of the hydrodynamic bearing (68). The orifice (84) vents hot compressed air that may leak past the seal (74) prior to reaching the hydrodynamic thrust bearing (68).