Cryogenic Refrigerator Drive Shaft Pressure Assist Against Motor Slippage
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Solution Overview
Problem
Cryogenic refrigerators with motor-driven displacers face issues of motor synchronization loss due to increased drive torque, caused by pressure loss and structural complexity, leading to potential motor slippage and reduced cooling efficiency.
Innovation Solution
Incorporating a branch pipe to supply high-pressure fluid to a space between the drive shaft and housing, reducing motor load torque and preventing synchronization loss by utilizing the pressure as an assist force, while simplifying the refrigerator's structure and reducing leakage risks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a motor is used to drive the displacer in a GM refrigerator, then the refrigerator can achieve cryogenic temperatures, but the motor may lose synchronization due to increased drive torque
Solution Approach 1:
The patent applies pneumatic principles by introducing a assist space connected to the high-pressure gas source, where pressurized gas acts on the drive shaft to provide an assist force. This pneumatic assistance reduces the torque burden on the motor, preventing synchronization loss while maintaining the ability to achieve cryogenic temperatures through the GM refrigeration cycle.
2Power
If the drive mechanism is designed to handle high torque, then the motor can drive the displacer, but the structure becomes more complex
Solution Approach 1:
Instead of designing a mechanically complex drive mechanism to handle high torque, the patent uses pneumatic assistance through the assist space. The high-pressure gas provides force directly to the drive shaft, simplifying the mechanical structure while still enabling the motor to drive the displacer with sufficient torque.
3Productivity
If high-pressure working gas is supplied to the displacer, then cooling efficiency is improved, but pressure loss increases
Solution Approach 1:
The patent recovers and utilizes the high-pressure working gas that would otherwise be wasted. By connecting the assist space to the high-pressure gas source through a control valve, the system repurposes the pressure energy to provide assist force to the drive shaft, thereby reducing the net pressure loss while maintaining cooling efficiency.
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 reduces motor load torque, prevents motor slippage, and maintains cooling efficiency even under increased pressure losses or capacity enhancements, while simplifying the refrigerator's configuration and reducing the risk of internal gas leakage.
Implementation Method 1
a supply pipe that is connected to a space formed between the drive shaft and the housing and is configured to supply the high-pressure fluid from the high-pressure fluid supply source to the space
Data Source
AI summary
A cryogenic refrigerator includes a compressor that compresses a working gas; a displacer to which the working gas compressed by the compressor is supplied; a drive mechanism that includes a drive shaft and is configured to drive the displacer; a motor that drives the drive mechanism; a housing that accommodates the drive mechanism; a valve mechanism that adjusts a pressure of the working gas supplied to the displacer; a pipe that supplies the working gas from the compressor to the valve mechanism; and a branch pipe that branches out from the supply pipe and is connected to a space formed between the drive shaft and the housing.