A Stirling refrigerator life monitoring device and method

Abstract

The present invention relates to a Stirling refrigerator life monitoring device and method, and relates to the technical field of Stirling refrigerators. The method comprises the following steps: Step 1: monitoring the gas condition in the compressor in the initial state, obtaining a pressure value curve a of the total gas pressure and a pressure value curve b of the partial pressure of the working gas; the pressure value curve a and the pressure value curve b are the same curve A; Step 2: monitoring the gas condition in the compressor in the working state, obtaining a pressure value curve a' of the total gas pressure and a pressure value curve b' of the partial pressure of the working gas; Step 3: comparing the pressure value curve a' in Step 2 with the pressure value curve b', and comparing them with the pressure value curve A obtained in Step 1, to determine the leakage and contamination status of the working gas in the compressor. By comparing the pressure value curve of the total gas pressure and the pressure value curve of the partial pressure of the working gas, the performance of the Stirling refrigerator can be monitored, making it convenient for operators to perform targeted maintenance on the Stirling refrigerator.

Description

Technical Field

[0001] The present invention relates to the technical field of Stirling refrigerators, and in particular to a Stirling refrigerator life monitoring device and method. Background Art

[0002] The highly reciprocating motion between the piston and cylinder of a Stirling refrigerator causes severe wear between them. Furthermore, non-volatile substances and impurities generated by friction can degrade the refrigerator's performance, leading to failure. A Stirling refrigerator failure can cause the infrared detector chip it cools to reach a high temperature (relative to 80K), resulting in image degradation and even damage to the detector.

[0003] The main reasons for the failure of a Stirling refrigerator at the end of its life are leakage of the working fluid and contamination of the working fluid. The Stirling refrigerator has three sealing structures, namely the motor surface, the compressor sealing surface and the expansion seal surface. Stirling refrigerators generally use gases with smaller molecules as the working fluid, which will bring certain challenges to the sealing work. In particular, the large temperature difference in the storage environment of the Stirling refrigerator and the long working time may cause leakage of the working fluid gas in the Stirling refrigerator. The adhesives used in the parts inside the Stirling refrigerator, the surfaces of the metal parts, and the grease used in the bearings will all slowly outgas, and the residual air will pollute the purity of the working gas, causing the performance of the Stirling refrigerator to deteriorate.

[0004] Existing techniques typically use a single pressure sensor to measure the internal pressure of a Stirling refrigerator. This only involves comparing the initial and operating pressures, resulting in low accuracy. This makes it difficult to determine whether the cause is a working gas leak or contamination, hindering subsequent targeted adjustments to the refrigerator. Therefore, a Stirling refrigerator life monitoring device and method are proposed. Summary of the Invention

[0005] The present invention provides a Stirling refrigerator life monitoring device and method for monitoring the leakage and contamination of working gas inside the Stirling refrigerator, thereby judging the performance of the Stirling refrigerator and avoiding serious consequences caused by sudden failure of the Stirling refrigerator.

[0006] The present invention provides a Stirling refrigerator life monitoring method, comprising the following steps:

[0007] Step 1: Monitor the gas conditions in the compressor at the initial state, and obtain a pressure value curve a of the total gas pressure and a pressure value curve b of the gas partial pressure of the working gas;

[0008] The pressure value curve a and the pressure value curve b are the same curve A.

[0009] Step 2: Monitor the gas condition in the compressor in the working state, and obtain a pressure value curve a' of the total gas pressure and a pressure value curve b' of the gas partial pressure of the working gas;

[0010] Step 3: Compare the pressure value curve a' and the pressure value curve b' obtained in step 2, and compare with the pressure value curve A obtained in step 1 to determine the leakage and contamination status of the working fluid gas in the compressor.

[0011] In one embodiment, in step 2, the pressure value curve a' and the pressure value curve b' are the same curve B, and the amplitude and peak value of the pressure wave of curve B are equal to those of curve A, then the internal airtightness of the Stirling refrigerator is good.

[0012] In one embodiment, in step 2, if the pressure value curve a' and the pressure value curve b' are the same curve B, and the amplitude and peak value of the pressure wave of curve B are smaller than those of curve A, the internal working fluid gas of the Stirling refrigerator is leaking.

[0013] In one embodiment, in step 2, the pressure value curve a' is curve B, the pressure value curve b' is curve C, the amplitude and peak value of the pressure wave of curve B are both smaller than those of curve A, and the amplitude and peak value of the pressure wave of curve C are both smaller than those of curve B, then the internal working fluid gas of the Stirling refrigerator is contaminated.

[0014] In one embodiment, the pressure wave amplitude of the curve A is 0.2 MPa and the peak value is 1.8 MPa.

[0015] In one embodiment, the pressure wave amplitude of the curve B ranges from 0.14 to 0.2 MPa, and the peak value ranges from 1.3 to 1.8 MPa.

[0016] In one embodiment, the warning value of the peak difference between the curve B and the curve A is 0.5 MPa.

[0017] In one embodiment, the warning value of the peak difference between the curve B and the curve C is 0.4 MPa.

[0018] The present invention provides a Stirling refrigerator life monitoring device comprising: a first pressure sensor and a second pressure sensor, wherein the probe of the first pressure sensor and the probe of the second pressure sensor are respectively connected to the interior of the compressor of the Stirling refrigerator through a connecting hole on the compressor end cover of the Stirling refrigerator.

[0019] In one embodiment, a polymer membrane is provided at the probe of the second pressure sensor, and the polymer membrane is used to pass working gas molecules and block other gas molecules, thereby facilitating the second pressure sensor to measure the working gas partial pressure.

[0020] Compared with the prior art, the advantage of the present invention is that by comparing the pressure value curve of the total gas pressure with the pressure value curve of the partial pressure of the working fluid gas, it is possible to quickly and accurately determine whether the failure of the Stirling refrigerator is caused by leakage of the working fluid gas or contamination, thereby monitoring the performance of the Stirling refrigerator, making it convenient for operators to respond in a timely manner to the failure of the Stirling refrigerator due to leakage or contamination of the working fluid gas, and to perform targeted maintenance on the Stirling refrigerator. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Hereinafter, the present invention will be described in more detail based on embodiments with reference to the accompanying drawings.

[0022] Figure 1 Schematic diagram of the positions of the pressure sensor and the Stirling refrigerator of the present invention;

[0023] Figure 2 is a cross-sectional schematic diagram of the installation of the pressure sensor of the present invention;

[0024] Figure 3 is a schematic diagram of a pressure value curve of the pressure sensor of the present invention;

[0025] Reference numerals:

[0026] 1. Compressor; 2. First pressure sensor; 3. Second pressure sensor; 4. Polymer membrane. DETAILED DESCRIPTION

[0027] The present invention will be further described below with reference to the accompanying drawings.

[0028] The present invention discloses a Stirling refrigerator life monitoring method, comprising the following steps:

[0029] Step 1: Monitor the gas conditions within the compressor in the initial state to obtain a pressure curve a for the total gas pressure and a pressure curve b for the partial pressure of the working gas. The internal pressure of the compressor can be detected using a first pressure sensor 2 and a second pressure sensor 3 connected to the interior of the compressor to obtain pressure curves a and b, respectively. At this point, the pressure curves obtained by the two pressure sensors are equal, both representing curve A.

[0030] When the Stirling refrigerator is in the initial state, the pressure value curves generated by the first pressure sensor 2 and the second pressure sensor 3 are the same, both of which are curve A. The pressure wave amplitude of curve A is 0.2 MPa and the peak value is 1.8 MPa. This data is used as a standard indicator for subsequent evaluation of whether the Stirling refrigerator has working fluid gas leakage and contamination.

[0031] In this embodiment, the working fluid gas of the Stirling refrigerator is preferably helium. In order to measure the helium partial pressure when the internal helium of the compressor is contaminated, the second pressure sensor 3 can also be a piezoelectric pressure sensor, a capacitive pressure sensor, or a piezoresistive pressure sensor.

[0032] Step 2: Monitor the gas conditions in the compressor under working conditions, and obtain the pressure value curve a' of the total gas pressure and the pressure value curve b' of the gas partial pressure of the working gas, that is, use the first pressure sensor 2 to measure the pressure value curve a', and the second pressure sensor 3 to measure the pressure value curve b'.

[0033] Step 3: Compare the pressure value curve a' and the pressure value curve b' in step 2, and compare them with the pressure value curve A obtained in step 1 to determine the leakage and contamination status of the working gas in the compressor.

[0034] In step 3, if the pressure value curve a' and the pressure value curve b' are the same curve B, and the amplitude and peak value of the pressure wave of curve B are equal to those of curve A, the internal airtightness of the Stirling refrigerator is good.

[0035] Example 1

[0036] In step 3, the pressure value curve a' and the pressure value curve b' are the same curve B, and the amplitude and peak value of the pressure wave of curve B are smaller than those of curve A, such as Figure 3 As shown, the pressure wave amplitude range of curve B should be 0.14~0.2MPa, and the peak range should be 1.3~1.8MPa. When the pressure wave amplitude and peak value of curve B exceed the range, that is, the peak difference between curve B and curve A exceeds the warning value of 0.5MPa, it is judged that the working fluid gas in the Stirling refrigerator is leaking.

[0037] However, the pressure amplitude of curve B is 0.18 MPa, with a peak value of 1.58 MPa, indicating a helium leak within the Stirling refrigerator. The difference between the peak values ​​of curves B and A is 0.22 MPa. Therefore, although helium has leaked, it has not yet reached the warning value of 0.5 MPa and has not yet completely affected the cooling efficiency of the Stirling refrigerator. Therefore, the Stirling refrigerator can be replaced for the time being.

[0038] Since the Stirling refrigerator is still in a state of internal helium leakage, the sealing surface of the Stirling refrigerator can be checked. If there are discontinuities such as pits, wear, or radial or penetrating scratches, repairs can be carried out to improve the sealing effect of the Stirling refrigerator.

[0039] Example 2

[0040] In step 3, the pressure value curve a' and the pressure value curve b' are the same curve B, and the amplitude and peak value of the pressure wave of the same curve B are both smaller than those of curve A. At this time, the pressure wave amplitude of curve B is 0.14 MPa and the peak value is 1.3 MPa, indicating that there is a helium leak inside the Stirling refrigerator.

[0041] The difference between the peak values ​​of curve B and curve A is 0.5 MPa, so the helium inside the Stirling refrigerator is leaking, affecting the refrigeration effect of the Stirling refrigerator, and the Stirling refrigerator needs to be replaced.

[0042] Example 3

[0043] In step 3, the pressure value curve a' and the pressure value curve b' are the same curve B, and the amplitude and peak value of the pressure wave of the same curve B are both smaller than those of curve A. At this time, the pressure wave amplitude of curve B is 0.14 MPa and the peak value is 1.2 MPa, indicating that there is a helium leak inside the Stirling refrigerator.

[0044] At this point, the difference between the peak values ​​of curves B and A is 0.6 MPa, exceeding the warning value of 0.5 MPa. Therefore, helium is leaking inside the Stirling refrigerator, affecting its cooling efficiency and requiring replacement. For this replacement, repairs can be performed on the Stirling refrigerator's seal, such as replacing the sealing ring. Ensure that the sealing ring, sealing thread, and sealing surface are smooth and free of impurities.

[0045] Example 4

[0046] In a mixed gas, the pressure formed when a certain component occupies the same volume as the mixed gas at the same temperature is the gas partial pressure of the gas, and the partial pressure of the gas is less than the total pressure of the mixed gas.

[0047] In the present invention, the mechanical parts inside the Stirling refrigerator cavity will absorb gas and release it after a long time, the grease in the bearings will evaporate, and the air in the inflation will be impurity gases. After the Stirling refrigerator has been working for a long time, the impurity gases will enter the working gas and pollute the working gas.

[0048] In step 3, when the pressure value curve a' is curve B, the pressure value curve b' is curve C, and the amplitude and peak value of the pressure wave of curve B are both smaller than those of curve A, and the amplitude and peak value of the pressure wave of curve C are both smaller than those of curve B, as shown in FIG. Figure 3As shown, when the peak value difference between curve B and curve C exceeds the warning value of 0.4 MPa, it is determined that the working gas in the Stirling refrigerator is contaminated.

[0049] At this time, the pressure wave amplitude of curve B is 0.18 MPa, the peak value is 1.58 MPa, and the pressure wave amplitude of curve C is 0.17 MPa, the peak value is 1.47 MPa, which means that the internal working fluid gas of the Stirling refrigerator is contaminated.

[0050] However, the difference between the peak values ​​of curves B and C is 0.11 MPa. Therefore, although the helium inside the Stirling refrigerator is contaminated, it has not yet reached the warning value of 0.4 MPa and has not yet completely affected the refrigeration effect of the Stirling refrigerator. The Stirling refrigerator can be replaced for the time being, but it needs to be repaired in a timely manner to extend its service life. When repairing a Stirling refrigerator with helium contamination, the Stirling refrigerator can be high-temperature baked to remove the accumulated contaminants. High-purity nitrogen can then be refilled multiple times in the high-temperature baking environment to replace and remove the air and contaminants inside the Stirling refrigerator.

[0051] Example 5

[0052] In step 3, the pressure value curve a' is curve B, the pressure value curve b' is curve C, and the amplitude and peak value of the pressure wave of curve B are both smaller than those of curve A, and the amplitude and peak value of the pressure wave of curve C are both smaller than those of curve B. At this time, if the pressure wave amplitude of curve B is 0.16MPa and the peak value is 1.42MPa, and the pressure wave amplitude of curve C is 0.14MPa and the peak value is 1.02MPa, then the internal working fluid gas of the Stirling refrigerator is contaminated.

[0053] The difference between the peak values ​​of curves B and C is 0.4 MPa, and the warning value between curves B and C is 0.4 MPa. In order to prevent the cooling capacity of the Stirling cooler from being unable to meet the temperature requirements of the infrared detector in the future, the Stirling cooler needs to be replaced.

[0054] Example 6

[0055] In step 3, the pressure value curve a' is curve B, the pressure value curve b' is curve C, and the amplitude and peak value of the pressure wave of curve B are both smaller than those of curve A, and the amplitude and peak value of the pressure wave of curve C are both smaller than those of curve B. At this time, if the pressure wave amplitude of curve B is 0.18MPa and the peak value is 1.58MPa, and the pressure wave amplitude of curve C is 0.16MPa and the peak value is 1.09MPa, then the internal helium gas of the Stirling refrigerator is contaminated.

[0056] However, the difference between the peaks of curves B and C is 0.49 MPa, exceeding the warning value of 0.4 MPa between curves B and C. The Stirling cooler's cooling capacity can no longer meet the infrared detector's temperature requirements, and the cooler needs to be replaced. Similarly, since the Stirling cooler was detected to be contaminated with helium, this condition can be used to perform targeted repairs on the replaced cooler.

[0057] The present invention provides a Stirling refrigerator life monitoring device, comprising: a first pressure sensor 2 and a second pressure sensor 3, wherein the probe of the first pressure sensor 2 and the probe of the second pressure sensor 3 are respectively connected to the interior of the Stirling refrigerator compressor 1 through a connecting hole on the end cover of the Stirling refrigerator compressor 1, such as Figure 1 As shown. The first pressure sensor 2 and the second pressure sensor 3 are electrically connected to an amplifier, which is electrically connected to an oscilloscope, and the data is read and stored by the oscilloscope. The present invention is provided with at least two pressure sensors, and more pressure sensors can be added to improve measurement accuracy.

[0058] The first pressure sensor 2 and the second pressure sensor 3 are both miniature high-frequency pressure sensors. In this embodiment, the Kunshan Shuangqiao GY506 miniature low-pressure sensor is preferred. The probe of the second pressure sensor 3 is provided with a polymer film 4, such as Figure 2 As shown, the polymer membrane 4 is used to pass the working gas molecules and block other gas molecules, so as to facilitate the second pressure sensor 3 to measure the partial pressure of the working gas.

[0059] The first pressure sensor 2 and the second pressure sensor 3 can be connected and installed with the end cover of the compressor 1 of the Stirling refrigerator in a threaded connection manner.

[0060] The working gas in the present invention can be selected based on specific refrigeration requirements and operating conditions, and nitrogen or hydrogen can be used. The polymer membrane 4 provided at the probe of the second pressure sensor 3 must also be adjusted based on the actual working gas selected to ensure that working gas molecules can pass through the polymer membrane 4 while preventing other impurity gas molecules from passing through the polymer membrane 4. In the embodiments of the present invention, helium is preferred as the working gas due to its advantages such as low inertial mass, stable physical properties, and low leakage rate. Therefore, the polymer membrane 4 at the probe of the second pressure sensor 3 must also be selected to allow helium molecules to pass through while preventing other gas molecules from passing through.

[0061] While the present invention has been described with reference to preferred embodiments, various modifications may be made and equivalent components may be substituted without departing from the scope of the present invention. In particular, the various technical features described in the various embodiments may be combined in any manner, provided no structural conflicts exist. The present invention is not limited to the specific embodiments disclosed herein, but encompasses all technical solutions within the scope of the claims.

Claims

1. A Stirling refrigerator life monitoring method, characterized in that: The following steps are involved: Step 1: Monitor the gas conditions in the compressor at the initial state, and obtain a pressure value curve a of the total gas pressure and a pressure value curve b of the gas partial pressure of the working gas; Wherein, the pressure value curve a and the pressure value curve b are the same curve A; Step 2: Monitor the gas condition in the compressor in the working state, and obtain a pressure value curve a' of the total gas pressure and a pressure value curve b' of the gas partial pressure of the working gas; Step 3: Compare the pressure value curve a' and the pressure value curve b' obtained in step 2, and compare them with the pressure value curve A obtained in step 1 to determine the leakage and contamination status of the working gas in the compressor; Wherein, in step 2, the pressure value curve a' and the pressure value curve b' are the same curve B, and the amplitude and peak value of the pressure wave of the curve B are equal to those of the curve A, then the internal airtightness of the Stirling refrigerator is good; In step 2, if the pressure value curve a' and the pressure value curve b' are the same curve B, and the amplitude and peak value of the pressure wave of curve B are smaller than those of curve A, then the internal working fluid gas of the Stirling refrigerator is leaking; In step 2, the pressure value curve a' is curve B, the pressure value curve b' is curve C, the amplitude and peak value of the pressure wave of curve B are both smaller than those of curve A, and the amplitude and peak value of the pressure wave of curve C are both smaller than those of curve B, then the internal working fluid gas of the Stirling refrigerator is contaminated.

2. The Stirling refrigerator life monitoring method according to claim 1, characterized in that: The pressure wave amplitude of the curve A is 0.2 MPa, and the peak value is 1.8 MPa.

3. The Stirling refrigerator life monitoring method according to claim 1, characterized in that: The pressure wave amplitude of the curve B ranges from 0.14 to 0.2 MPa, and the peak value ranges from 1.3 to 1.8 MPa.

4. The Stirling refrigerator life monitoring method according to claim 1, characterized in that: The warning value of the peak difference between the curve B and the curve A is 0.5 MPa.

5. The Stirling refrigerator life monitoring method according to claim 1, characterized in that: The warning value of the peak difference between the curve B and the curve C is 0.4 MPa.

6. A Stirling refrigerator life monitoring device, used to implement the monitoring method according to any one of claims 1 to 5, characterized in that: include: a first pressure sensor and a second pressure sensor, The probe of the first pressure sensor and the probe of the second pressure sensor are both connected to the interior of the compressor of the Stirling refrigerator through the connecting holes on the compressor end cover of the Stirling refrigerator.

7. The Stirling refrigerator life monitoring device according to claim 6, characterized in that: A polymer membrane is provided at the probe of the second pressure sensor. The polymer membrane is used to pass working gas molecules and block other gas molecules, so as to facilitate the second pressure sensor to measure the partial pressure of the working gas.

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