Cryocooler and starting method of cryocooler
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Solution Overview
Problem
Existing cryocoolers require expensive temperature sensors to detect the completion of initial cooling, making them costly and complicating the detection process, which limits the affordability and efficiency of cryogenic temperature achievement.
Innovation Solution
A cryocooler system that includes an expander with an exhaust temperature sensor and a controller to compare the measured exhaust temperature to a reference temperature, allowing for the completion of initial cooling without the need for a cryogenic temperature sensor, using either the exhaust or intake temperature as a reference, and also utilizing pressure sensors to determine cooling completion based on pressure changes in the gas lines.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If expensive cryogenic temperature sensors are used to detect cooling completion, then measurement precision is improved, but device cost increases
Solution Approach 1:
The patent uses exhaust temperature as an intermediary parameter to indirectly determine cooling stage completion. Instead of directly measuring the cryogenic temperature at the cooling stage, the system measures the exhaust temperature of the working gas from the expander, which correlates with the cooling stage temperature. This intermediary measurement approach allows using general-purpose temperature sensors rather than expensive cryogenic sensors.
Solution Approach 2:
The patent replaces the need for direct cryogenic temperature measurement with a pressure-based detection method. By measuring pressure changes in the high-pressure or low-pressure lines during the cooling process, the system can determine cooling completion without requiring temperature sensors capable of operating at cryogenic temperatures. This substitution eliminates the need for expensive specialized sensors.
2Measurement precision
If direct cooling stage temperature measurement is implemented, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent employs exhaust temperature and pressure as intermediary parameters that can be measured at accessible locations in the system. The exhaust temperature sensor is placed in the exhaust line of the expander, and pressure sensors are placed in the high-pressure or low-pressure lines, avoiding the need to install sensors directly at the difficult-to-access cooling stage.
Solution Approach 2:
The patent extracts the temperature measurement function from the cooling stage itself and relocates it to the exhaust line. By measuring the temperature of the working gas after it has expanded through the expander, the system obtains information about the cooling stage temperature without physically placing a sensor in the cryogenic environment.
3Device complexity
If pressure sensors are used to determine cooling completion, then device cost decreases, but measurement precision may be reduced
Solution Approach 1:
The patent implements a feedback control system where pressure measurements are continuously monitored and compared against predetermined pressure values. When the pressure reaches the predetermined threshold, the system receives feedback that cooling completion has been achieved. This feedback mechanism ensures accurate detection despite using less precise pressure sensors.
Solution Approach 2:
The patent utilizes the change in pressure as a parameter that indicates cooling progression. By monitoring how pressure evolves during the cooling process and identifying specific pressure thresholds that correspond to cooling stage completion, the system achieves accurate detection using pressure as a proxy parameter rather than direct temperature measurement.
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
Enables the detection of initial cooling completion at a lower cost by using general-purpose temperature sensors and pressure measurements, reducing the need for expensive cryogenic temperature sensors and improving the affordability and efficiency of cryogenic temperature attainment.
Implementation Method 1
an exhaust temperature sensor that measures an exhaust temperature which is a temperature of the working gas exhausted from the expander
Implementation Method 2
a pressure sensor that measures a pressure of the high pressure line or a pressure of the low pressure line
Implementation Method 3
an expander that includes a cooling stage... initial cooling in which the cooling stage is cooled from an initial temperature to a cryogenic temperature
Data Source
AI summary
A cryocooler includes an expander that includes a cooling stage, an exhaust temperature sensor that measures an exhaust temperature which is a temperature of a working gas exhausted from the expander and outputs an exhaust temperature signal indicating the measured exhaust temperature, and a controller that compares, during execution of initial cooling in which the cooling stage is cooled from an initial temperature to a cryogenic temperature, the measured exhaust temperature to a reference temperature based on the exhaust temperature signal and completes the initial cooling in a case where a temperature difference between the measured exhaust temperature and the reference temperature is within a reference range.