Hermetic Compressor Oil Separation to Prevent Refrigerant Backflow
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Solution Overview
Problem
Conventional hermetic compressors face issues with oil deficiency and reduced cooling capability due to oil and refrigerant mixing, leading to inefficient heat exchange and compressor reliability problems, as existing oil recollecting apparatuses cause refrigerant backflow and increased refrigerant temperature, resulting in decreased cooling performance.
Innovation Solution
A hermetic compressor design incorporating an oil separator and dual oil pumps to separate and recollect oil from refrigerant, with a backflow prevention mechanism to ensure oil is not mixed with refrigerant, enhancing oil recollection efficiency and maintaining optimal compressor operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an oil separator is installed at the outlet of the compressor to separate oil from refrigerant, then oil can be separated from the discharged refrigerant, but the separated oil and refrigerant may backflow to the inlet of the compressor causing refrigerant deficiency and low cooling capability
Solution Approach 1:
An oil pump is introduced as an intermediary device between the oil separator and the compressor inlet. The oil pump actively transports separated oil back to the compressor while allowing refrigerant to flow through to the condenser, preventing backflow and maintaining refrigerant circulation in the refrigeration cycle.
Solution Approach 2:
The system separates the oil recollection function from the refrigerant flow path by using dedicated oil pump circuits. Oil is extracted and returned through separate pathways controlled by the oil pump, while refrigerant flows independently through the condenser and evaporator, preventing mixed backflow.
2Reliability
If high-temperature oil and refrigerant are sucked to the inlet of the compressor, then oil can be recaptured, but the suction refrigerant temperature increases reducing the amount of refrigerant sucked and lowering cooling capability
Solution Approach 1:
The oil pump acts as an intermediary that selectively removes oil from the discharge line before it can mix with and heat the suction refrigerant. By intercepting and returning oil through a separate path, the system prevents thermal contamination of the cold suction refrigerant.
Solution Approach 2:
Oil is extracted from the hot discharge refrigerant stream at the oil separator and immediately pumped back to the compressor through a separate circuit. This extraction prevents oil from remaining in the refrigeration cycle where it would absorb heat and raise suction refrigerant temperature.
3Productivity
If the oil separated by the oil separator is mixed with a sucked refrigerant thus to be discharged from the compression unit, then oil can be recirculated, but oil deficiency occurs within the inner space of the casing lowering compressor reliability
Solution Approach 1:
The oil pump serves as a controlled intermediary that directs separated oil back into the compressor's inner space through specific pathways. This ensures oil is delivered to where it is needed for lubrication without being diluted or mixed with suction refrigerant that would carry it out of the system.
Solution Approach 2:
The system creates a self-sufficient oil circulation loop where oil separated from the refrigerant is automatically pumped back into the compressor's oil reservoir. This self-service mechanism maintains adequate oil levels in the compressor without relying on oil mixing with refrigerant for recirculation.
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 prevents oil deficiency and refrigerant backflow, maintaining compressor reliability and enhancing refrigeration cycle performance by ensuring separate handling of oil and refrigerant, thereby improving cooling capability and heat exchange efficiency.
Implementation Method 1
an oil separator in fluid communication with an outlet of the compressor and configured to separate oil from the compressed refrigerant discharged from the compression unit
Implementation Method 2
an oil pump in fluid communication with the oil separator and configured to pump oil separated by the oil separator into the inner space of the casing
Implementation Method 3
a backflow preventing portion formed at a housing which accommodates the oil pump and configured to prevent oil from back-flowing from the inner space of the casing to the oil separator
Implementation Method 4
a crankshaft coupled to the driving motor, the compression unit, and the oil pump and configured to transmit a driving force of the driving motor to both the compression unit and the oil pump
Data Source
AI summary
To a hermetic compressor and a refrigeration cycle device having the same, an oil separator for separating oil from a refrigerant discharged from a compression unit is added. Separated oil is recollected into an oil pump driven by a driving motor. Because refrigerant separated from the oil is prevented from being re-introduced into the compressor, a cooling capability of the refrigeration cycle device may be enhanced. Because the oil pump is driven by the driving force of the driving motor, the compressor may have a simplified configuration, and the fabrication costs may be reduced. The oil used for a crankshaft lubrication process is returned to the oil pump by forming an oil pocket between bearing surfaces of a crankshaft and the oil pump, oil may be prevented from back-flowing to the oil separator from the crankshaft. This may allow oil to be smoothly recollected into the oil pump.