Cryocooler and cryocooler operation method

Patent metadata

Field	Value
Publication number	US-11073308-B2
Application number	US-201816228731-A
Country	US
Kind code	B2
Filing date	Dec 20, 2018
Priority date	Jul 23, 2014
Publication date	Jul 27, 2021
Grant date	Jul 27, 2021

Abstract

In a cryocooler for developing coldness of 4 K or lower by expanding helium, an expander expands high-pressure helium. A compressor compresses low-pressure helium returned from the expander, to generate high-pressure helium, and supplies the high-pressure helium to the expander. When helium temperature in the expander is 2.17 K or lower, the pressure of the low-pressure helium is equal to or higher than pressure given by a curve, in a helium state diagram in which the horizontal axis is temperature and the vertical axis is pressure, along which helium's volumetric thermal expansion coefficient is 0.

First claim

What is claimed is:

1. A cryocooler system for cooling helium to around or below 4 K, the cryocooler system comprising:
an expander for expanding the helium;
a compressor for compressing the helium, returned from the expander, to supply the helium to the expander;
a helium gas line assembly connecting the expander to the compressor, the helium gas line assembly having a low-pressure line on a low-pressure side of the compressor, and a high-pressure line on a high-pressure side of the compressor; and
a helium tank section connected to the low-pressure side of the compressor, the helium tank section comprising:
a helium tank, wherein the helium is helium-4,
a connection line connecting the helium tank to the low-pressure line of the helium gas line assembly,
a valve-control-signal controllable valve installed in the connection line,
a helium tank controller configured to control a cryocooler operation pressure on the low-pressure side of the compressor to 15 bar or higher through the connection line, the helium tank controller communicably connected with the valve for sending a valve control signal to the valve,
whereby the cryocooler operation pressure on the low-pressure side of the compressor is controlled to 15 bar or higher;

wherein the expander comprises a two-stage expander, whereby a second-stage cooling unit of the two-stage expander is cooled below 2.17 K through expansion of the helium down to the cryocooler operation pressure within the second-stage cooling unit.

2. The cryocooler system according to claim 1 , wherein the helium tank controller is configured to control the cryocooler operation pressure on the low-pressure side of the compressor to 25 bar or higher through the connection line.

3. The cryocooler system according to claim 1 , wherein the two-stage expander is a two-stage GM expander.

4. The cryocooler system according to claim 1 , wherein the helium tank controller comprises a valve control unit configured to generate the valve control signal to open the valve during stopping operation of the expander and the compressor, wherein an initial pressure of the helium tank is an average pressure of the low-pressure side and the high-pressure side of the compressor.

5. The cryocooler system according to claim 1 , wherein the helium tank section further comprises a pressure sensor for measuring the cryocooler operation pressure on the low-pressure side of the compressor, the pressure sensor communicably connected with the helium tank controller to output a measured pressure to the helium tank controller.

6. The cryocooler system according to claim 1 , wherein the helium tank section further comprises a temperature sensor for measuring a temperature of the expander, the temperature sensor communicably connected with the helium tank controller to output a measured temperature to the helium tank controller.

7. The cryocooler system according to claim 6 , wherein the helium tank controller comprises a temperature comparison unit and a valve control unit.

8. The cryocooler system according to claim 7 , wherein the temperature comparison unit is configured to compare the measured temperature with a temperature threshold value and to output results of the temperature comparison as input into the valve control unit.

9. The cryocooler system according to claim 8 , wherein the valve control unit is configured to generate the valve control signal for adjustably opening and closing the valve according to the input from the temperature comparison unit, the valve control unit via the valve control signal closing the valve when the measured temperature is greater than the temperature threshold value, and opening the valve when the measured temperature is less than or equal to the temperature threshold value.

10. The cryocooler system according to claim 5 , wherein the helium tank controller comprises a pressure comparison unit and a valve control unit.

11. The cryocooler system according to claim 10 , wherein the pressure comparison unit is configured to compare the measured pressure with a pressure threshold value and to output results of the pressure comparison as input into the valve control unit.

12. The cryocooler system according to claim 11 , wherein the valve control unit is configured to generate the valve control signal for adjustably opening and closing the valve according to the input from the pressure comparison unit, the valve control unit via the valve control signal closing the valve when the measured pressure is greater than the pressure threshold value, and opening the valve when the measured pressure is less than or equal to the pressure threshold value.

Assignees

• Sumitomo Heavy Industries

Inventors

• De Waele A T A M
• Xu Mingyao
• Bao Qian

Classifications

• F25B9/12

  using 3He-4He dilution · CPC title

• F25B9/14 Primary

  characterised by the cycle used, e.g. Stirling cycle · CPC title

• F25B2309/14

  Compression machines, plants or systems characterised by the cycle used · CPC title

• F25B9/06 Primary

  using expanders (F25B9/10 takes precedence) · CPC title