Bearing for supporting a rotating compressor shaft
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Solution Overview
Problem
HVACR compressors face issues with stall, surge, and shock loads, which lead to increased radial and axial loads on the shaft, causing damage to foil gas and magnetic thrust bearings due to excessive compression and contact, resulting in performance degradation.
Innovation Solution
The use of a combination of radial and thrust foil gas bearings backed up by ball bearings, and a radial mesh foil bearing with an actuator to increase stiffness, prevents plastic deformation and contact during harsh operating conditions by limiting compression to a predetermined amount, ensuring the ball bearings support the shaft before damage occurs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If foil gas bearings are used to support the shaft, then operational efficiency is improved, but the bearings are damaged during stall, surge, and shock loads due to excessive compression
Solution Approach 1:
The patent applies beforehand cushioning by positioning ball bearings as backup support elements that engage before the foil gas bearing can be excessively compressed during stall, surge, or shock load conditions. The ball bearing acts as a protective cushion that limits the maximum compression of the foil bearing, preventing plastic deformation while allowing the foil bearing to operate efficiently under normal conditions.
Solution Approach 2:
The ball bearing serves as an intermediary protective element between the shaft and the foil gas bearing. During harsh operating conditions, the ball bearing engages first and limits the load transmission to the foil bearing, preventing direct excessive compression that would cause damage. This intermediary mechanism allows the foil bearing to maintain its efficiency benefits while being protected from destructive loads.
2Adaptability or versatility
If the shaft is allowed to rotate freely, then operational flexibility is improved, but the bump foil can be plastically deformed during harsh operating conditions
Solution Approach 1:
The patent applies preliminary anti-action by having the ball bearing positioned to counteract excessive shaft displacement before plastic deformation of the bump foil can occur. During stall, surge, or shock loads, the ball bearing engages and provides opposing support force that prevents the shaft from compressing the foil bearing beyond its elastic limit, thereby protecting the structural integrity of the foil while maintaining operational flexibility under normal conditions.
3Force
If mesh foil bearing stiffness is increased, then load support capability is improved, but the device complexity increases due to actuator requirements
Solution Approach 1:
The patent applies dynamics by making the mesh foil bearing stiffness adjustable through an actuator system. The actuator can compress the mesh structure to increase stiffness when higher load support capability is required, and release when normal operating conditions prevail. This dynamic adjustment allows the bearing to adapt its mechanical properties to match operational requirements, optimizing load support capability while avoiding permanent high-stiffness construction that would increase baseline 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
This configuration enhances the operational efficiency and durability of HVACR compressors by preventing damage to bearings during stall, surge, and shock loads, maintaining performance and reducing wear, while allowing operation within higher efficiency areas.
Implementation Method 1
a foil gas bearing for supporting the shaft while rotating
Implementation Method 2
a radial ball bearing configured to contact and radially support the shaft when the shaft compresses the radial foil gas bearing by a predetermined amount
Implementation Method 3
the actuator is configured to be actuated with compressed gas to compress the wire mesh dampener. the compression of the wire mesh dampener by the actuator increases the stiffness of the top foil
Data Source
AI summary
A compressor includes a housing, a shaft that is rotated relative to the housing to compress a working fluid, and a foil bearing that supports the shaft. The foil bearing includes a top foil. The foil bearing is a foil gas bearing that is backed up by a ball bearing, or a mesh foil bearing with an actuator to compress a wire mesh dampener. A heat transfer circuit includes a compressor and a working fluid. The compressor includes a shaft that is rotated to compress the working fluid, and a foil bearing for supporting the shaft as it rotates.