Tilting Pad Bearing Casing Structure for Heat Shrinkage Control
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Solution Overview
Problem
Centrifugal compressors experience heat shrinkage issues due to low-temperature working fluids, leading to reduced clearance between the rotating shaft and the bearing, which can cause seizure.
Innovation Solution
A compressor design featuring an annular groove and connection portion in the casing to stabilize the bearing, suppressing heat shrinkage effects and maintaining bearing clearance by enhancing rigidity at the pivot support points.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the casing is made as a vertically divided type for ease of assembly and maintenance, then the ease of manufacture is improved, but the bearing becomes affected by heat shrinkage over the entire circumference leading to reduced clearance and potential seizure
Solution Approach 1:
The annular groove divides the head into inner and outer circumferential regions, segmenting the heat shrinkage effect. The groove acts as a barrier that prevents heat shrinkage from propagating uniformly across the entire bearing circumference, thereby maintaining bearing clearance while preserving the vertically divided casing structure for ease of assembly.
Solution Approach 2:
The groove is strategically positioned at a specific location in the head to create localized structural differentiation. This local modification allows the bearing region to be protected from heat shrinkage while maintaining the overall vertically divided casing design, achieving both ease of manufacture and bearing reliability.
2Reliability
If a groove is formed in the casing to block heat shrinkage, then the bearing clearance is maintained, but the structural integrity and rigidity of the casing may be compromised
Solution Approach 1:
The groove is implemented as a localized feature rather than a complete circumferential cut, maintaining structural integrity in regions away from the groove. This local modification blocks heat shrinkage propagation while preserving the overall rigidity and strength of the casing structure.
Solution Approach 2:
The groove extends partially through the head thickness and covers only the necessary circumferential portion to block heat shrinkage, rather than creating a complete separation. This partial action is sufficient to protect the bearing while minimizing impact on casing strength.
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
Stable support of the bearing is achieved, reducing the risk of seizure and effectively managing heat shrinkage across the entire circumference.
Implementation Method 1
the temperature of a casing of the compressor disposed around the flow path or a member, such as a bearing supporting a rotating shaft, drops. As a result, heat shrinkage occurs in these members
Data Source
AI summary
A compressor includes a tilting pad bearing supporting a rotating shaft in a casing. The tilting pad bearing includes a bearing pad being in sliding contact with an outer circumferential surface of the rotating shaft and a pivot supporting the bearing pad in a swingable manner. The casing includes a groove portion having an annular shape recessed in the axial direction and extending in the circumferential direction, and a connection portion configured to connect an inner circumferential region of an inner side in the radial direction with respect to the groove portion to an outer circumferential region of the outer side in the radial direction with respect to the groove portion. The connection portion overlaps with the pivot as viewed from the axial direction.