Scroll Compressor Drive Shaft Sealing for Oil Leakage
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Solution Overview
Problem
In scroll compressors, increased motor rotation speed leads to excessive lubrication oil supply, causing oil leakage from the bearing's lower end and subsequent leakage of refrigerant, resulting in unwanted oil discharge and reduced lubrication within the compressor casing.
Innovation Solution
A compressor design featuring a sealing part with an oil receiving surface and a stepped surface on the rotary drive shaft, utilizing centrifugal force to redirect lubrication oil away from the bearing's lower end, and oil return grooves to guide excess oil back into the casing, reducing leakage and maintaining adequate lubrication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the rotation speed of the motor is increased to increase the circulation amount of fluid, then the productivity is improved, but the amount of lubrication oil supplied to the bearing exceeds the collection capacity of the oil groove, causing oil leakage
Solution Approach 1:
The invention divides the shaft structure into two segments: a large-diameter shaft part supported by the bearing and a small-diameter shaft part connected to the lower end. This segmentation creates a stepped surface that forms a seal clearance, preventing excessive lubrication oil from leaking down while allowing the oil groove to collect sufficient lubrication oil at normal operating speeds.
Solution Approach 2:
The seal clearance formed between the oil receiving surface and the stepped surface acts as an intermediary barrier. It selectively blocks excessive lubrication oil during high-speed operation while permitting adequate lubrication oil to reach the bearing during normal operation, thus mediating between the conflicting requirements of lubrication supply and leakage prevention.
2Speed
If the rotation speed of the motor is increased, then the amount of lubrication oil supplied to the bearing increases, but the oil groove cannot collect the excessive oil, causing it to leak from the bearing
Solution Approach 1:
The invention employs dynamic sealing through the seal clearance that utilizes centrifugal force generated by rotation. At higher rotation speeds, the centrifugal force effectively blocks excessive lubrication oil from leaking through the clearance, while at normal speeds, adequate lubrication oil can still reach the bearing. This dynamic mechanism adapts the sealing effectiveness to the operating speed.
Solution Approach 2:
The invention changes the physical parameters of the shaft structure by creating a stepped surface with different diameters. This geometric parameter change forms a seal clearance with specific dimensions that allow selective passage of lubrication oil based on flow rate and centrifugal force, thereby maintaining reliable oil containment across varying operating conditions.
3Ease of operation
If lubrication oil leaks from the lower end of the bearing, then the oil flows out from the casing through the outlet pipe, but this causes unwanted oil discharge and reduced lubrication within the compressor
Solution Approach 1:
The invention converts the potentially harmful effect of excessive lubrication oil flow into a beneficial sealing mechanism. The seal clearance, which could be seen as a potential leakage path, is instead designed to utilize centrifugal force at high speeds to block excessive oil, thereby converting what would be a harmful leakage into a beneficial automatic flow control mechanism that prevents unwanted oil discharge.
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 solution effectively suppresses lubrication oil leakage, preventing its discharge with refrigerant and ensuring sufficient lubrication within the compressor, thereby reducing unwanted oil loss and maintaining operational efficiency even at high rotation speeds.
Implementation Method 1
utilizing centrifugal force to redirect lubrication oil away from the bearing's lower end
Implementation Method 2
an oil supply passage formed in the rotary drive shaft to supply lubrication oil to a clearance between the rotary drive shaft and the bearing
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
A compressor (1) prevents lubrication oil from leaking from a lower end of a bearing (3) and flowing out from a casing (5). The compressor (1) includes a compression mechanism (7), a drive shaft (11), a bearing (3) for the drive shaft (11), and an oil supply passage (29) configured to supply lubrication oil to a clearance between the drive shaft (11) and the bearing (3). The drive shaft (11) includes a large-diameter shaft part (11f) supported by the bearing (3), and a small-diameter shaft part (11g) connected to a lower end part of the large-diameter shaft part (11f). A sealing part (10) configured to reduced or prevent oil leakage from the bearing (3) includes an oil receiving surface (26) facing a circular stepped surface (12) formed at a boundary between the large-diameter shaft part (11f) and the small-diameter shaft part (11g) and being apart from the stepped surface (12) with a clearance.