Journal Bearing Dual-Path Cooling for Air Machine
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Solution Overview
Problem
Existing air machines with journal bearings for central shafts lack effective cooling solutions, leading to potential overheating and reduced efficiency in air compression and turbine operation.
Innovation Solution
A dual path cooling system is implemented, where cooling air is directed between the outer periphery of the shaft and the inner periphery of the journal bearing, with communication holes allowing air to flow from the outer periphery to the inner bore of the shaft, providing comprehensive cooling along the length of the bearing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a single path cooling system is used for journal bearings, then the structure is simpler, but the cooling effectiveness is insufficient leading to overheating
Solution Approach 1:
The cooling system is divided into two separate cooling paths: an outer cooling path that directs cooling air between the outer periphery of the shaft and the inner periphery of the journal bearing, and an inner cooling path that directs cooling air between the inner periphery of the shaft and the outer periphery of the bearing. This segmentation allows each path to independently cool specific regions, effectively reducing bearing temperature without requiring excessive complexity in any single path.
Solution Approach 2:
The cooling paths are arranged in a nested configuration where the inner cooling path is positioned within the shaft's hollow interior, while the outer cooling path operates in the annular space between the shaft and bearing. The connection holes through the shaft wall link these nested cooling paths, creating an integrated dual-path system that maximizes cooling effectiveness while maintaining compact structure.
2Temperature
If cooling air flow is increased to improve cooling effectiveness, then temperature control improves, but the system requires more complex flow distribution mechanisms
Solution Approach 1:
The total cooling air flow is segmented into two distinct paths with separate flow distribution mechanisms. The outer cooling path receives cooling air at the outer periphery of the shaft and distributes it along the bearing outer surface. The inner cooling path receives cooling air through connection holes and distributes it along the bearing inner surface. This segmentation allows independent optimization of each path's flow distribution without requiring a single complex distribution system.
Solution Approach 2:
The connection holes through the shaft wall serve as intermediaries that link the outer and inner cooling paths. These holes allow cooling air to transition from the outer cooling path to the inner cooling path, enabling coordinated temperature control across the entire bearing assembly without requiring direct mechanical connection or complex control mechanisms between the two paths.
3Reliability
If traditional single path cooling is used, then the system is simpler, but operational efficiency and longevity are reduced due to overheating
Solution Approach 1:
The bearing cooling is segmented into two independent cooling zones corresponding to the inner and outer peripheries of the bearing. Each zone has its dedicated cooling path that can be independently controlled and optimized. This segmentation ensures uniform temperature distribution across the entire bearing, preventing localized overheating that would reduce reliability and longevity, while keeping each individual cooling path relatively simple.
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 cooling system enhances the operational efficiency and longevity of the air machine components by maintaining optimal temperatures, reducing wear and tear, and ensuring consistent performance.
Implementation Method 1
A cooling air path provides cooling air between the outer periphery of the shaft and the inner periphery of the bearing
Implementation Method 2
The cooling air then passes through the inner bore of the shaft and along a length of the bearing
Data Source
AI summary
A compressor rotor compresses air and delivers the compressed air to a downstream inlet and across a turbine rotor. A shaft rotates with the turbine rotor and the compressor rotor. The shaft is hollow with an inner bore and an outer periphery. At least one journal bearing supports a portion of the shaft, and has an inner bore spaced from the outer periphery of the shaft. A cooling air path is provided between the shaft outer periphery and the bearing inner periphery, and along a length of the bearing to at least one connection hole. The connection hole provides cooling air from an outer periphery of the shaft to the inner bore of the shaft. In a separate feature, a shaft for use in an air supply machine includes a hollow interior, with such a connection hole.