Compressor Eccentric Pressure Reduction Groove
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In rotary compressors, the dissolution of gas refrigerant in lubrication oil leads to reduced thermal conductivity between sliding surfaces, hindering effective cooling, especially in compact designs where surface pressure and heat generation increase, necessitating efficient cooling measures for thrust bearings.
Innovation Solution
A pressure reduction groove is formed in the eccentric part of the drive shaft to separate gas refrigerant from lubrication oil, allowing only the denser lubrication oil to flow between the thrust bearing surfaces, enhancing cooling efficiency and reducing abrasive wear.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the diameter of the eccentric part is reduced to make the compressor more compact, then the size of the compressor is reduced, but the surface pressure of the thrust bearing increases and heat generation due to friction increases
Solution Approach 1:
The pressure reduction groove is formed in advance in the eccentric part to pre-process the lubrication oil pressure before it reaches the thrust bearing. This preliminary pressure reduction allows gas refrigerant to be separated from the lubrication oil before the oil contacts the bearing surface, ensuring that only liquid oil with high thermal conductivity reaches the bearing to effectively cool the high-pressure, high-heat generation area caused by compact design.
2Reliability
If lubrication oil containing dissolved gas refrigerant is supplied to the thrust bearing, then lubrication is provided, but the thermal conductivity between the sliding surfaces decreases due to gas bubbles, reducing cooling efficiency
Solution Approach 1:
The pressure reduction groove segments the lubrication oil flow path into two zones: a high-pressure zone where oil is supplied from the oil path, and a low-pressure zone where gas refrigerant separates from the oil. This segmentation allows the lubrication function to be maintained in the high-pressure zone while the cooling function is optimized in the low-pressure zone where gas-free oil is supplied to the thrust bearing.
Solution Approach 2:
The pressure reduction groove acts as an intermediary structure between the oil path and the thrust bearing. It mediates the lubrication oil by reducing its pressure and separating the gas refrigerant, thereby transforming the oil from a state that cannot effectively cool (containing gas bubbles) to a state that provides both lubrication and effective cooling (gas-free liquid oil).
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 separates gas refrigerant from lubrication oil, ensuring efficient cooling of thrust bearing surfaces and minimizing abrasive wear, thereby improving the operational efficiency and reliability of rotary compressors, especially in high-load and compact designs.
Implementation Method 1
A pressure reduction groove (65) opening at the thrust bearing surface (26a), extending in a circumferential direction, and configured to reduce a pressure of the lubrication oil supplied from the oil path (70) to the pressure reduction groove (65) is formed in the eccentric part (26).
Implementation Method 2
Gas refrigerant is dissolved in the lubrication oil supplied from the oil path (70) to the pressure reduction groove (65), and the pressure of the lubrication oil is reduced in the pressure reduction groove (65). As a result, the gas refrigerant dissolved in the lubrication oil is separated, and bubbles of the gas refrigerant are generated in the lubrication oil.
Implementation Method 3
Since the lubrication oil has a specific gravity greater than that of the gas refrigerant, centrifugal force acting on the lubrication oil is greater than that acting on the gas refrigerant. Thus, when the gas refrigerant is separated from the lubrication oil in the pressure reduction groove (65), the gas refrigerant is accumulated in an upper part of the pressure reduction groove (65). Meanwhile, the lubrication oil having the specific gravity greater than that of the gas refrigerant receives great centrifugal force, and then flows out from the pressure reduction groove (65) toward the outside in the radial direction.
Implementation Method 4
Lubrication oil is supplied between the lower end surface of the eccentric part and the upper end surface of the lower end plate, i.e., between sliding surfaces of the thrust bearing, and cools the sliding surfaces of the thrust bearing to reduce abrasive wear of the sliding surfaces of the thrust bearing.
Implementation Method 5
Lubrication oil is supplied between the lower end surface of the eccentric part and the upper end surface of the lower end plate, i.e., between sliding surfaces of the thrust bearing, and cools the sliding surfaces of the thrust bearing to reduce abrasive wear of the sliding surfaces of the thrust bearing.
Data Source
AI summary
A rotary compressor includes a drive mechanism having a drive shaft with an eccentric part, and a compression mechanism. The compression mechanism includes a tubular cylinder covering an outer periphery of the eccentric part, a piston arranged inside the cylinder and fitted onto the eccentric part, an upper end plate closing an upper end of the cylinder, and a lower end plate closing a lower end of the cylinder. A lower end surface of the eccentric part defines a thrust bearing surface slidably contacting an upper end surface of the lower end plate. The drive shaft has an oil path with lubrication oil circulating through the oil path. The eccentric part has a circumferentially extending pressure reduction groove opening at part of the thrust bearing surface close to an inner circumferential side to reduce a pressure of the lubrication oil supplied from the oil path to the pressure reduction groove.