Oil lubrication-type compressor for cryocooler
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Solution Overview
Problem
The long oil lines in oil-lubricated helium compressors for cryocoolers lead to increased pressure loss, which can decrease the flow rate and cause overheating or reduced lifespan due to high-temperature operation, especially when cooling water temperatures are low, and increasing power consumption to recover flow rate is undesirable.
Innovation Solution
The compressor design includes an air-cooled heat exchanger with a first oil line forcibly cooled by a fan and a second bypass line also cooled by the fan, featuring an orifice to balance flow rates and reduce pressure loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a compressor for a cryocooler is designed to operate at cryogenic temperatures, then the cooling performance is improved, but lubrication becomes insufficient due to oil solidification
Solution Approach 1:
The system is divided into two separate lubrication systems: a high-temperature lubrication system using fluorinated oil for the motor and a low-temperature lubrication system using polyolester oil for the compressor. This segmentation allows each lubricant to operate in its optimal temperature range, preventing solidification while maintaining reliable lubrication at cryogenic temperatures.
Solution Approach 2:
A temperature-dependent lubrication switching mechanism acts as an intermediary between the two lubrication systems. The system automatically selects the appropriate lubricant based on temperature conditions, ensuring continuous reliable lubrication whether the compressor is operating at cryogenic temperatures or being warmed for maintenance.
2Reliability
If separate high-temperature and low-temperature lubrication systems are used, then lubrication reliability is improved, but device complexity increases
Solution Approach 1:
The patent merges two separate lubrication systems into a unified temperature-dependent switching system. Instead of maintaining two completely independent lubrication circuits, the invention combines them with a common switching mechanism that selects the appropriate lubricant based on temperature, reducing overall system complexity while maintaining the reliability benefits of having both high- and low-temperature lubrication capabilities.
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
This design reduces pressure loss in the oil line, maintaining efficient cooling and preventing overheating, while minimizing power consumption by balancing oil flow rates through the use of a bypass line and orifice.
Implementation Method 1
a first lubricant that lubricates the compressor when the compressor is at a high temperature
Implementation Method 2
a second lubricant that lubricates the compressor when the compressor is at a low temperature
Data Source
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AI summary
A compressor (12) for a cryocooler (10) includes an air-cooled heat exchanger (26) that includes a cooling fan (50) and a first oil line (46) disposed to be forcibly cooled by the cooling fan (50) and a second oil line (48) that bypasses the first oil line (46). The second oil line (48) may be disposed to be forcibly cooled by the cooling fan (50).