Compressor with wear sleeve and method of retrofitting a compressor
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Solution Overview
Problem
Vapor compression systems, such as HVACR systems, face premature wear of moving parts due to debris-laden fluids, particularly with low GWP refrigerants that are soluble in lubricants, leading to reduced lubrication effectiveness and increased corrosion, resulting in abrasive wear and reduced lubricant film thickness.
Innovation Solution
Implementing a compressor with a wear-resistant sleeve-like treatment on the shaft, combined with a high viscosity polyol ester lubricant and additives like anti-wear, corrosion inhibitor, and acid catching agents, which together mitigate wear and chemical reactions, allowing intermittent contact with small hard particles and maintaining effective lubrication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a standard shaft without wear protection is used, then the compressor structure remains simple and manufacturing cost is low, but the shaft experiences excessive abrasive wear from debris-laden fluids, leading to premature failure
Solution Approach 1:
The patent applies a composite material solution by coating the shaft with a wear-resistant material (such as chromium oxide, ceramic, or other hard coatings) to create a multi-layer structure. This composite approach combines the structural integrity of the base shaft material with the superior wear resistance of the coating, allowing the shaft to withstand abrasive debris-laden fluids while maintaining operational reliability.
Solution Approach 2:
The wear-resistant coating acts as an intermediary layer between the shaft and the debris-laden fluid. This intermediate protective layer absorbs the wear and damage from abrasive particles, preventing direct contact between the debris and the shaft material, thereby extending shaft life without requiring fundamental structural changes.
2Reliability
If a low viscosity lubricant is used, then the lubricant flows easily and reduces friction, but the lubricant film thickness is insufficient, leading to increased wear and reduced protection against debris
Solution Approach 1:
The patent changes the viscosity parameter of the lubricant by selecting or formulating a lubricant with higher viscosity than conventional options. This parameter change increases the lubricant film thickness, providing better protection against abrasive wear from debris-laden fluids while maintaining adequate flow characteristics to reduce friction between moving parts.
3Reliability
If conventional lubricants without additives are used, then the lubricant composition remains simple and cost-effective, but the lubricant breaks down quickly in the presence of debris and chemical reactions occur, reducing protection
Solution Approach 1:
The patent applies a composite lubricant formulation by combining the base lubricant with specific additives (such as anti-wear additives, corrosion inhibitors, and antioxidants). This composite composition provides enhanced stability and protection against chemical reactions and breakdown in the presence of debris-laden fluids, while the additives work synergistically to maintain lubrication effectiveness.
4Reliability
If the shaft is made from harder material to resist wear, then wear resistance improves, but the shaft becomes more susceptible to brittleness and catastrophic failure, and manufacturing becomes more difficult
Solution Approach 1:
The patent segments the shaft into two functional zones: the core shaft maintains its original material composition for toughness and structural integrity, while the outer surface receives a wear-resistant coating. This segmentation allows each zone to optimize its properties - the core provides ductility and impact resistance, while the coating provides abrasion resistance, avoiding the brittleness associated with making the entire shaft from hard material.
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 combination of a wear-resistant sleeve-like treatment and high viscosity lubricant with additives significantly reduces excessive wear and chemical reactions, ensuring continued operation and extended lifespan of compressor components by maintaining an effective lubricant film thickness.
Implementation Method 1
The compressor shaft is rotated within a compressor housing. A hard coating layer is applied to a portion of the compressor shaft to mitigate compressor shaft wear from small particle debris
Implementation Method 2
The lubricant is a polyol ester (POE) lubricant with a viscosity of at least 70 centistokes at 40°C, and at least 10 centistokes at 100°C
Implementation Method 3
the additives include one or more of anti-wear additives, corrosion inhibitor additives, antioxidant additives, and acid catching additives
Implementation Method 4
the additives include one or more of anti-wear additives, corrosion inhibitor additives, antioxidant additives, and acid catching additives
Data Source
Figure 1
Figure 2A
Figure 2B
AI summary
A compressor including a housing, a shaft configured to be rotated relative to the housing to compress a refrigerant, a motor configured to drive the shaft, a lubrication system configured to supply lubricant to the compressor, and a bearing configured to support the shaft. The shaft includes a wear-resistant sleeve-like treatment on at least a portion of an outer surface of the shaft adjacent the bearing. The lubricant is POE oil or a lubricant blend composition that includes two or more lubricants, the two or more lubricants including a first lubricant and a second lubricant.