Reverse-Direction Bearing Cooling Path for Cabin Air Compressors
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Solution Overview
Problem
Existing aircraft environmental control systems face complexity and maintenance challenges due to the use of separate air compressors, which also impact fuel efficiency.
Innovation Solution
A compressor design with a motor and rotor on a common axis, featuring a reverse direction bearing cooling flow path that directs cooling fluid to the most highly loaded rotor shaft journal bearing, utilizing a separate cooling stream for the motor and a split cooling stream for the rotor shaft, enhancing cooling efficiency and reducing maintenance needs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a separate air compressor is used to provide pressurized air to the environmental control system, then the system complexity and maintenance needs are reduced, but the cooling efficiency of the motor and bearings deteriorates
Solution Approach 1:
The cooling system is segmented into multiple independent cooling paths: a motor cooling path with its own inlet and flow distribution, and a bearing cooling path with separate cooling fluid inlet positioned adjacent to the bearing support. This segmentation allows optimized cooling for each component without interfering with the other, resolving the contradiction by maintaining simple system architecture while achieving effective cooling.
Solution Approach 2:
The cooling fluid inlet for the bearing is positioned locally adjacent to the bearing support, and cooling fluid is distributed through specific flow paths directly to the bearing and motor areas. This local quality approach ensures that cooling is delivered precisely where needed, improving cooling efficiency without adding overall system complexity.
2Reliability
If cooling fluid is directed to the most highly loaded rotor shaft journal bearing, then the bearing cooling efficiency is improved, but the device complexity increases
Solution Approach 1:
The cooling fluid inlet is positioned and configured in advance to deliver cooling fluid directly to the most highly loaded rotor shaft journal bearing before the bearing experiences excessive heating. The bearing support structure is designed with integrated cooling passages that pre-establish the cooling flow path, eliminating the need for complex active control systems while ensuring optimal cooling of the critical bearing.
3Temperature
If a separate cooling stream is provided for the motor and a split cooling stream is provided for the rotor shaft, then the cooling efficiency is improved, but the device complexity increases
Solution Approach 1:
The bearing support structure serves multiple functions: it provides mechanical support for the rotor shaft journal bearing and simultaneously houses the cooling fluid inlet and flow distribution passages. This multi-functionality allows separate cooling streams for the motor and rotor shaft to be implemented through a unified bearing support structure, improving cooling efficiency without proportionally increasing device complexity.
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
The design improves cooling efficiency and reduces maintenance requirements, thereby enhancing the reliability and fuel efficiency of the environmental control system.
Implementation Method 1
a cooling fluid inlet disposed adjacent to the bearing support and in fluid communication with the first journal bearing
Implementation Method 2
cooling a motor and bearings of a compressor
Data Source
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AI summary
A compressor includes a compressor rotor (16) and a motor (18) disposed about a common axis. The motor (18) includes a rotor shaft (20) coupled to the compressor rotor (16) and configured to drive the compressor rotor (16); a thrust shaft (22) disposed at an opposite end of the motor (18) from the rotor shaft (20); a tie rod (24) disposed on the common axis and extending through the rotor shaft (20), thrust shaft (22), and the compressor rotor (16); a first journal bearing disposed about the rotor shaft (20) and concentrically about the common axis to radially support the rotor shaft (20); a journal bearing support disposed concentrically about the first journal bearing; and a cooling fluid inlet disposed adjacent to the journal bearing support and in fluid communication with the first journal bearing. The rotor shaft (20) includes a plurality of orifices. The tie rod (24) axially retains the compressor rotor (16) at a forward end and the motor (18) at an aft end.