Heating rod

Abstract

A heating rod, comprising: a first cylindrical body portion and a second cylindrical body portion, a first heating strip arranged inside the first cylindrical body portion, and a second heating strip arranged inside the second cylindrical body portion. The first cylindrical body portion and the second cylindrical body portion, which match the shape of a cryocooler cylinder, respectively heat a first cylinder portion and a second cylinder portion by means of the first heating strip and the second heating strip.

Description

[0001] This application relates to the field of refrigeration equipment used in superconducting magnet devices, specifically a heating rod, and more particularly a heating rod used for maintaining and repairing a cryostat housed in a vacuum container. Background Art: Superconducting magnets require extremely low temperatures to operate. In the prior art, cryostats are often used to cool superconducting magnet devices with vacuum containers, creating a suitable working environment for the superconducting magnets. The cryostat has a cylinder and a gas transfer device housed within the cylinder. To prevent abnormal operation of the cryostat from affecting the superconducting magnets in the superconducting magnet device, regular maintenance of the cryostat is required. Considering the high temperature requirements of superconducting magnets, the temperature of the cryostat cylinder and the gas transfer device housed within the cylinder is close to absolute zero. When maintaining the cryostat, the gas transfer device needs to be removed from the cylinder. At this time, air enters the cylinder, and water vapor in the air precipitates under extremely low temperatures and freezes inside the cylinder, which may cause problems such as gas transfer device jamming. In the prior art, to avoid problems such as air entering the cylinder and causing icing on the cylinder walls during refrigeration maintenance, the exposed part of the refrigeration unit is wrapped in a plastic bag before the transfer device is removed, and the plastic bag is secured to the vacuum container with tape, ensuring a sealed environment inside the plastic bag. The transfer device is then removed to prevent external air from entering the cylinder and icing. However, even with a plastic bag isolating the cylinder from external air, it is still impossible to completely prevent air from condensing inside the plastic bag within the cylinder. This application aims to provide a heating rod for maintaining a refrigeration unit located in a vacuum container, in order to at least solve or alleviate some of the problems existing in the prior art. This application provides a heating rod for maintaining a refrigeration unit located in a vacuum container, comprising: a first cylindrical body portion; a second cylindrical body portion with a diameter smaller than the diameter of the first cylindrical body portion and protruding from the end of the first cylindrical body portion; a first heating strip built into the first cylindrical body portion; and a second heating strip built into the second cylindrical body portion. In an optional technical solution, a first heating strip is arranged parallel to the axial direction of the first cylindrical body and extends through the end of the first cylindrical body; a second heating strip is arranged parallel to the axial direction of the second cylindrical body and extends through the end of the second cylindrical body. In an optional technical solution, the heating rod further includes: a first thermocouple correspondingly disposed on the first heating strip; and a second thermocouple correspondingly disposed on the second heating strip. In an optional technical solution, the heating rod further includes: a third thermocouple built into the first heating strip, and a fourth thermocouple built into the second heating strip.In an optional technical solution, the heating rod further includes: a first temperature controller corresponding to the first thermocouple, which controls the temperature of the first cylindrical body portion based on the temperature detected by the first thermocouple; and a second temperature controller corresponding to the second thermocouple, which controls the temperature of the second cylindrical body portion based on the temperature detected by the second thermocouple. In an optional technical solution, the heating rod further includes: a third temperature controller corresponding to the third thermocouple, which controls the temperature of the first heating strip based on the temperature detected by the third thermocouple; and a fourth temperature controller corresponding to the fourth thermocouple, which controls the temperature of the second heating strip based on the temperature detected by the fourth thermocouple. In an optional technical solution, the heating rod further includes: a plurality of first thermocouples arranged in a manner surrounding the first cylindrical body portion. In an optional technical solution, the heating rod further includes: a gas channel built into the first cylindrical body portion and the second cylindrical body portion, parallel to the axial direction of the second cylindrical body portion, and penetrating the ends of the first cylindrical body portion and the second cylindrical body portion. In an optional technical solution, the heating rod further includes: a gas channel inlet disposed on one end side of the first cylindrical body portion and communicating with a gas channel; and a gas channel outlet disposed on one end side of the second cylindrical body portion and communicating with a gas channel. In an optional technical solution, the heating rod further includes: an overheat protection switch that controls the shutdown of the first and / or second thermostats when the temperature of the first and / or second cylindrical body portions exceeds a first predetermined threshold. In an optional technical solution, the heating rod further includes: an overheat protection switch that controls the shutdown of the third and / or fourth thermostats when the temperature of the first and / or second heating bars exceeds a second predetermined threshold. Figure 1 is a schematic diagram of the structure of a refrigerator installed in a superconducting magnet device according to one embodiment of this application. Figure 2 is a schematic diagram of the structure of a heating rod provided in one embodiment of this application. Figure 3 is a cross-sectional view (AA) of the heating rod provided in Figure 2. Figure 4 is a cross-sectional view (AA) of the heating rod provided in Figure 2. Figure 5 is a cross-sectional view (BB) of the heating rod provided in Figure 2. Figure 6 is a cross-sectional view of the heating rod shown in Figure 2.Reference numerals in the drawings: 1. Superconducting magnet device; 11. Refrigeration unit; 12. Vacuum container; 111. Motor; 112. Cylinder; 113. Gas transfer device; 1121. First cylinder section; 1122. Second cylinder section; 2. Heating rod; 2. First cylindrical body section; 201. Second cylindrical body section; 202. First heating bar; 203. Second heating bar; 204. First thermocouple; 205. Second thermocouple; 206. Third thermocouple; 2031. Fourth thermocouple; 2041. First temperature controller; 207. Second temperature controller; 208. Third temperature controller; 2032. Fourth temperature controller; 2042. Gas channel; 209. Gas channel inlet; 2091. Gas channel outlet; 2092. Detailed embodiments: It should be noted that the working principle, characteristics, and advantages of the refrigeration equipment according to this application will be described below by way of example. However, it should be understood that all descriptions are given for illustrative purposes only. Therefore, this should not be construed as imposing any limitation on this application. Furthermore, for any single technical feature described or implied in the embodiments mentioned herein, or any single technical feature shown or implied in the accompanying drawings, this application still allows for any combination or deletion of these technical features (or their equivalents) without any technical obstacle, thereby obtaining more other embodiments of this application that may not be directly mentioned herein.

[0002] <First Embodiment> Figure 1 is a schematic diagram of the structure of a cryostat installed in a superconducting magnet device according to one embodiment of this application. As shown in Figure 1, the superconducting magnet device 1 includes a vacuum container 12 with a cryostat 11 installed. The cryostat 11 installed in the superconducting magnet device 1 has a motor 111 protruding from the superconducting magnet device 1 and exposed to the air, a cylinder 112 corresponding to the motor 111 and installed in the superconducting magnet device 1, and a gas transfer device 113 connected to the motor 111 and housed in the cylinder 112. The cylinder 112 further includes a first cylinder portion 1121 with a first cylindrical diameter and a second cylinder portion 1122 with a second cylindrical diameter connected to the first cylinder portion 1121. Figure 2 is a schematic diagram of the structure of a heating rod provided in one embodiment of this application. As shown in Figure 2, the heating rod 2 includes: a first cylindrical body portion 201 and a second cylindrical body portion 202. As shown in Figure 2, the first cylindrical body portion 201 and the second cylindrical body portion 202 are coaxially arranged, and the second cylindrical body portion 202 protrudes from the end of the first cylindrical body portion 201 with a diameter smaller than that of the first cylindrical body portion 201. The shape and size of the first cylindrical body portion 201 shown in Figure 2 match the first cylinder portion 1121, and the shape and size of the second cylindrical body portion 202 match the second cylinder portion 1122. Figure 3 is a cross-sectional view AA of the heating rod provided in Figure 2. As shown in Figure 3, the first cylindrical body portion 201 is also provided with a first heating strip 203, and the second cylindrical body portion 202 is also provided with a second heating strip 204. Specifically, when performing maintenance on the freezer 11 of the vacuum container, the gas transfer device 113 needs to be removed from the cylinder 112. In the prior art, a sealed environment is created around the freezer 11 using a plastic bag (not shown) and tape (not shown). However, considering the temperature requirements of the superconducting magnet, the freezer 11 operates at a low temperature. At this point, the temperature in the gas transfer device 113 and the cylinder 112 is close to absolute zero. Furthermore, the plastic bag is not a vacuum environment, and some air may still enter the cylinder 112, causing water vapor to condense and adhere to the inner wall of the cylinder 112, resulting in the gas transfer device 113 becoming stuck. By inserting a heating rod 2 after removing the gas transfer device 113, the internal environment and walls of the cylinder 112 are heated, raising the internal temperature of the cylinder 112.The first cylindrical body portion 201 has a diameter and length corresponding to the first cylinder portion 1121, with its diameter slightly smaller than the first cylinder diameter to facilitate insertion and removal of the first cylinder portion 1121. The second cylindrical body portion 202 has a diameter and length corresponding to the second cylinder portion 1122, with its diameter slightly smaller than the second cylinder diameter to facilitate insertion and removal of the second cylinder portion 1122. Through the above embodiment, the overall structure of the heating rod 2 is matched with the internal space of the cylinder 112, reducing the air volume space inside the cylinder 112 after the heating rod 2 is inserted into it. This further reduces the amount of air that may enter the cylinder 112, and to a certain extent reduces the possibility of water vapor in the ambient air entering the cylinder 112 and condensing and adhering to the cylinder 112 wall under low temperature, causing the gas transfer device 113 to become stuck. By making the diameter of the first cylindrical body portion 201 slightly smaller than the first cylinder diameter, and the diameter of the second cylindrical body portion 202 slightly smaller than the second cylinder diameter, the heating rod 2 can be inserted into the cylinder 112 more conveniently and without contact, which helps to ensure the smooth progress of maintenance work. After the heating rod 2 is inserted into the cylinder 112, the first heating strip 203 built into the first cylindrical body portion 201 heats the first cylinder portion 1121, causing the inner wall temperature of the first cylinder portion 1121 to rise. The second heating strip 204 built into the second cylindrical body portion 202 heats the second cylinder portion 1122, causing the inner wall temperature of the second cylinder portion 1122 to rise. Considering the different capacities and inner wall areas of the first cylinder section 1121 and the second cylinder section 1122, the first heating strip 203 and the second heating strip 204 are used to heat the first cylinder section 1121 and the second cylinder section 1122 respectively. On the one hand, the output power and energizing time of the first heating strip 203 and the second heating strip 204 can be flexibly and independently controlled according to the different parameters of the first cylinder section 1121 and the second cylinder section 1122, effectively controlling the heating rate of the first cylinder section 1121 and the second cylinder section 1122, so that the temperature of the first cylinder section 1121 and the second cylinder section 1122 can be raised to the target temperature relatively quickly. On the other hand, by heating the first cylinder section 1121 and the second cylinder section 1122 respectively by the first heating strip 203 and the second heating strip 204, the problem of the second cylinder section 1122, which has a smaller capacity and inner wall area of ​​cylinder 112, being heated too quickly and causing a temperature difference between the first cylinder section 1121 and the second cylinder section 1122 is avoided when the same heating strip is used to heat the first cylinder section 1121 and the second cylinder section 1122 at the same time.In a preferred embodiment of this application, the first heating strip 203 is arranged parallel to the axial direction of the first cylindrical body portion 201 and extends through the end of the first cylindrical body portion 201; the second heating strip 204 is arranged parallel to the axial direction of the second cylindrical body portion 202 and extends through the end of the second cylindrical body portion 202. Specifically, the first heating strip 203 (or the second heating strip 204) is arranged parallel to the axial direction of the first cylindrical body portion 201 (or the second cylindrical body portion 202) and extends through the end of the first cylindrical body portion 201 (or the second cylindrical body portion 202), that is, the length of the first heating strip 203 (or the second heating strip 204) is the same as the length of the first cylindrical body portion 201 (or the second cylindrical body portion 202) in the axial direction, which effectively increases the heat exchange area between the heating rod 2 and the outside. When the heating rod 2 is inserted into the cylinder 112, the length of the first heating strip 203 (or the second heating strip 204) is consistent with the length of the first cylinder portion 1121 (or the second cylinder portion 1122) in the height direction. This maximizes the surface area adjacent to the interior of the first heating strip 203 (or the second heating strip 204) and the first cylinder portion 1121 (or the second cylinder portion 1122), improving heat exchange efficiency and allowing the internal temperature of the cylinder 112 to rise to the target temperature more quickly. Although the embodiments in this application are described in the form of a first heating strip 203 and a second heating strip 204, this application is not limited to this. Any method that raises the internal temperature of the cylinder 112 by using different heating devices, such as heating elements, should also be included within the scope of protection of this application. It should be noted that this application does not limit the number of the first heating bar 203 and the second heating bar 204. The arrangement of multiple first heating bars 203 and second heating bars 204 in the heating rod according to the heating requirements should also be included in the protection scope of this application.

[0003] <Second Embodiment> The heating rod 2 provided in the second embodiment of this application is the same as the heating rod 2 in the above-described embodiments of this application, and all use the same name or symbols. Therefore, they are identical and will not be repeated here. Figure 4 is a cross-sectional view of the heating rod provided in Figure 2 (AA section), and Figure 5 is a cross-sectional view of the heating rod provided in Figure 2 (BB section). Combining Figures 4 and 5, the heating rod 2 provided in this embodiment further includes: a first thermocouple 205, a second thermocouple 206, a third thermocouple 2031, a fourth thermocouple 2041, a first temperature controller 207, a second temperature controller 208, a third temperature controller 2032, and a fourth temperature controller 2042. The first thermocouple 205 is arranged adjacent to and parallel to the first heating strip 203, and the second thermocouple 206 is arranged adjacent to and parallel to the second heating strip 204. A third thermocouple 2031 is built into the first heating strip 203, and a fourth thermocouple 2041 is built into the second heating strip 204. A first temperature controller 207 is configured corresponding to the first heating strip 203 and the first thermocouple 205, and controls the output of the first heating strip 203 based on the temperature detection result fed back by the first thermocouple 205, thereby controlling the temperature of the first cylindrical body 201. A second temperature controller 208 is configured corresponding to the second heating strip 204 and the second thermocouple 206, and controls the output of the second heating strip 204 based on the temperature detection result fed back by the second thermocouple 206, thereby controlling the temperature of the second cylindrical body 202. Simultaneously, a third temperature controller 2032 controls the output of the first heating strip 203 based on the temperature detection result fed back by the third thermocouple 2031 built into the first heating strip 203. The fourth temperature controller 2042 controls the output of the second heating bar 204 based on the temperature detection result fed back by the fourth thermocouple 2041 built into the second heating bar 204. In a preferred embodiment of this application, the heating rod 2 further includes an overheat protection switch (not shown), which controls the first temperature controller 207 and / or the second temperature controller 208 to shut down when the temperature detection result fed back by the first thermocouple 205 or the second thermocouple 206 indicates that the temperature of the first cylindrical body portion 201 and / or the second cylindrical body portion 202 exceeds a first predetermined threshold T1.Preferably, the heating rod 2 further includes an overheat protection switch (not shown), which controls the third thermostat 2032 and / or the fourth thermostat 2042 to shut off when the temperature detection result fed back by the third thermocouple 2031 or the fourth thermocouple 2041 indicates that the temperature of the first heating bar 203 and / or the second heating bar 204 exceeds a second predetermined threshold T2. This serves to prevent overheating. Through the above embodiments, the temperature of the first cylindrical body portion 201 (or the second cylindrical body portion 202) is detected by the first thermocouple 205 (or the second thermocouple 206) provided corresponding to the first heating bar 203 (or the second heating bar 204), and then the temperature of the first cylindrical body portion 201 (or the second cylindrical body portion 202) is controlled according to the detection result of the first thermocouple 205 (or the second thermocouple 206). That is, when the temperature of the first cylindrical body portion 201 (or the second cylindrical body portion 202) exceeds a first predetermined threshold T1, for example 320K, the first temperature controller 207 (or the second temperature controller 208) is turned off to reduce or stop the heating output of the first heating bar 203 (or the second heating bar 204). To prevent the temperature of the first cylindrical body portion 201 (or the second cylindrical body portion 202) from becoming too high, which could affect the service life of the heating rod 2 or the first cylinder portion 1121 (or the second cylinder portion 1122), the following measures are taken: Conversely, when the temperature of the first cylindrical body portion 201 (or the second cylindrical body portion 202) is lower than the first predetermined threshold T1, i.e., when the temperature of the first cylindrical body portion 201 (or the second cylindrical body portion 202) is too low, the first thermostat 207 (or the second thermostat 208) is turned off, and the heating output of the first heating bar 203 (or the second heating bar 204) is increased or turned on, so that the internal temperature of the first cylinder portion 1121 (or the second cylinder portion 1122) rises, thus preventing water vapor in the air from entering the cylinder 112, condensing, and remaining inside the cylinder 112. Therefore, by setting a third thermocouple 2031 and a third temperature controller 2032 corresponding to the third thermocouple 2031 built into the first heating strip 203, and a fourth thermocouple 2041 and a fourth temperature controller 2042 corresponding to the fourth thermocouple 2041 built into the second heating strip 204, the temperature of the first heating strip 203 and the temperature of the second heating strip 204 can be detected quickly and accurately, and corresponding temperature control adjustments can be made in a timely manner based on the detected temperatures.The reason for rapidly and accurately detecting and adjusting the surface temperatures of the first heating strip 203 and the second heating strip 204 is that, during the manufacturing of the heating rod 2, it is necessary to apply a heat-resistant grease with good thermal conductivity to the surface of the first heating strip 203 and the second heating strip 204 to help the first heating strip 203 and the second heating strip 204 insert into the preset holes of the first cylindrical body part 201 and the second cylindrical body part 202. After the heating rod 2 is manufactured, grease will fill the gap between the surface of the first heating strip 203 (or the surface of the second heating strip 204) and the inner wall of the preset hole of the first cylindrical body 201 (or the inner wall of the preset hole of the second cylindrical body 202), thereby improving the heat exchange performance between the first heating strip 203 (or the second heating strip 204) and the first cylindrical body 201 (or the second cylindrical body 202), so that the temperature of the first cylindrical body 201 (or the second cylindrical body 202) can rise rapidly and transfer heat to the cylinder 112. Through the above implementation method, the temperature of the first heating strip 203 (or the second heating strip 204) can be quickly and directly detected by the third thermocouple 2031 (or the fourth thermocouple 204) built into the first heating strip 203 (or the second heating strip 204). Then, the temperature of the body and surface of the first heating strip 203 (or the second heating strip 204) can be controlled in a timely manner according to the detection result of the third thermocouple 2031 (or the fourth thermocouple 2041). That is, when the temperature of the body or surface of the first heating strip 203 (or the second heating strip 204) tends to exceed the second predetermined threshold T2, such as 473K or 523K, the third temperature controller 2032 (or the fourth temperature controller 2033) is controlled to turn off or reduce the output power in a timely manner, thereby stopping or reducing the heating output of the first heating strip 203 (or the second heating strip 204). To avoid the surface temperature of the first heating strip 203 or the second heating strip 204 becoming too high, exceeding the decomposition temperature of the grease (i.e., the second specified threshold T2), which could lead to the decomposition of the components in the grease adhering to the surface of the first heating strip 203 (or the surface of the second heating strip 204), or the chemical reaction of the additives in the grease under high temperature.Therefore, according to the above-described embodiments of this application, the output power or energizing time of the first heating strip 203 and the second heating strip 204 can be flexibly controlled based on the different parameters of the first cylinder section 1121 and the second cylinder section 1122, and the temperature detection feedback results of the first thermocouple 205, the second thermocouple 206, the third thermocouple 2031, and the fourth thermocouple 2041, respectively. While maintaining the normal performance of the lubricating grease, the heating rate of the first cylinder section 1121 and the second cylinder section 1122 can be rapidly increased, and the temperatures of the first cylinder section 1121 and the second cylinder section 1122 can be maintained stably within a preset temperature range. This also avoids the problem of a large temperature difference between the first cylinder section 1121 and the second cylinder section 1122 affecting the service life of the refrigerator 11. As a preferred embodiment of this application, multiple first thermocouples 205 can also be arranged around the first cylindrical body portion 201. Specifically, as a preferred solution, the first thermocouples 205 are no longer arranged individually corresponding to the first heating strip 203, but multiple first thermocouples 205 are arranged around the first cylindrical body portion 201. The multiple first thermocouples 205 detect the temperature of different parts of the first cylindrical body portion 201 respectively, and calculate the comprehensive temperature of the first cylindrical body portion 201. This avoids the problem that when the heating rod 2 is inserted into the cylinder 112, the local part of the first cylindrical body portion 201 that is closer to the first heating strip 203 will overheat, while the other parts of the first cylindrical body portion 201 will heat up slowly due to the low temperature environment in the cylinder 112, resulting in a temperature difference inside the first cylindrical body portion 201 and uneven heating of the inner surface of the first cylinder portion 1121. Preferably, multiple second thermocouples 206 can be arranged in the form of surrounding the second cylindrical body portion 202. The specific reasons and effects are the same as those for arranging multiple first thermocouples 205, and will not be repeated here. In this embodiment, although it has been described in the form that each thermocouple corresponds to a different temperature controller, namely the first temperature controller 207, the second temperature controller 208, the third temperature controller 2032, and the fourth temperature controller 2042, it is not limited to this. The scheme in which the temperature detection results of the first thermocouple 205, the second thermocouple 206, the third thermocouple 2031, and the fourth thermocouple 2041 are fed back to the same temperature controller, and the temperature controller controls the heating output or shut-off of the first heating strip 203 and the second heating strip 204, is also within the protection scope of this application.Furthermore, although the accompanying drawings show that the first thermocouple 205, the second thermocouple 206, the third thermocouple 2031, and the fourth thermocouple 2041 extend almost along the entire axial direction of the first heating strip 203 and the second heating strip 204, this is not a limitation. The measuring points of each thermocouple can be appropriately configured at suitable positions along the axial extension of the first heating strip 203 and the second heating strip 204. The positions shown in the accompanying drawings do not constitute a limitation on the scope of protection of this application.

[0004] <Third Embodiment> The heating rod provided in the third embodiment of this application is the same as the heating rod in the above-described embodiments of this application, and all descriptions using the same names or symbols are identical, and will not be repeated here. Figure 6 is a cross-sectional view AA provided in Figure 2. As shown in Figure 5, the heating rod 2 provided in this embodiment further includes: a gas channel 209, a gas channel inlet 2091, and a gas channel outlet 2092. The gas channel 209 is built into the first cylindrical body portion 201 and the second cylindrical body portion 202 in a direction parallel to the axis of the second cylindrical body portion 202, and passes through the ends of the first cylindrical body portion 201 and the second cylindrical body portion 202. The gas channel inlet 2091 is located on one side of the end of the first cylindrical body portion 201 and communicates with the gas channel 209. The gas channel outlet 2092 is located on one side of the end of the second cylindrical body portion 202 and communicates with the gas channel 209. When the heating rod 2 is inserted into the cylinder 112, considering that the diameter of the first cylindrical body 201 is slightly smaller than the first cylinder diameter, and the diameter of the second cylindrical body 202 is slightly smaller than the second cylinder diameter, meaning that the heating rod 2 and the inner surface of the cylinder 112 do not directly and completely form surface contact, leaving a certain space in the middle, in order to prevent air from entering the gap between the heating rod 2 and the inner surface of the cylinder 112, a gas with a low melting point and high thermal conductivity, such as nitrogen, can be used to fill this space. By providing a gas channel 209 in the heating rod 2 that runs through the ends of the first cylindrical body 201 and the second cylindrical body 202, nitrogen can enter the cylinder 112 through the gas channel 209. This avoids the problem of air entering the cylinder 112 when the inner surface temperature of the cylinder 112 is still low, causing water vapor in the air to precipitate and remain inside the cylinder 112, thus affecting the refrigeration unit 11. Simultaneously, nitrogen gas can enhance the conduction of heat from the heating rod 2 to the inner surface of the cylinder 112, thereby improving the heating efficiency of the cylinder 112. Through the above implementation method, when the heating rod 2 is used to heat the inside of the cylinder 112, a gas with a low melting point can be conveniently filled into the gap between the heating rod 2 and the inner surface of the cylinder 112 through the gas channel 209. This avoids the problem of air entering the inside of the cylinder 112 when the inner surface temperature is still low, causing water vapor in the air to precipitate and remain inside the cylinder 112, which would affect the refrigeration unit 11.On the other hand, by introducing nitrogen gas, which has a high thermal conductivity, into the cylinder 112, the heat exchange efficiency between the surface of the heating rod 2 and the cylinder 112 can be improved, allowing the internal surface temperature of the cylinder 112 to reach the target temperature more quickly. Although nitrogen gas is used as an example in the embodiments of this application, this application does not limit the type of gas. Any arrangement that introduces other gases with low melting points and high thermal conductivity through the gas channel 209 should be included within the scope of protection of this application. The above are merely preferred embodiments of this application and are not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the scope of protection of this application.

Claims

Claims 1. A heating rod for maintenance of a refrigerator provided in a vacuum container, characterized by include: First cylindrical body section; The second cylindrical body portion has a smaller diameter than the first cylindrical body portion and protrudes from the end of the first cylindrical body portion; the first heating strip is built into the first cylindrical body portion; and the second heating strip is built into the second cylindrical body portion.

2. The heating rod as described in claim 1, characterized in that, The first heating strip is arranged parallel to the axial direction of the first cylindrical body and passes through the end of the first cylindrical body; the second heating strip is arranged parallel to the axial direction of the second cylindrical body and passes through the end of the second cylindrical body.

3. The heating rod as described in claim 2, characterized in that, It also includes a first thermocouple, which is correspondingly disposed on the first heating strip; and a second thermocouple, which is correspondingly disposed on the second heating strip.

4. The heating rod as described in claim 3, characterized in that, It also includes a third thermocouple, which is built into the first heating strip; and a fourth thermocouple, which is built into the second heating strip.

5. The heating rod according to claim 3, characterized in that, It also includes a first temperature controller, configured corresponding to the first heating strip and the first thermocouple, which controls the temperature of the first cylindrical body portion based on the temperature detected by the first thermocouple; and a second temperature controller, configured corresponding to the second heating strip and the second thermocouple, which controls the temperature of the second cylindrical body portion based on the temperature detected by the second thermocouple.

6. The heating rod according to claim 4, wherein the heating rod is formed by a single piece of the heating wire. It also includes a third temperature controller, which is configured corresponding to the third thermocouple, and controls the temperature of the first heating bar based on the temperature detected by the third thermocouple; A fourth temperature controller, corresponding to the fourth thermocouple, controls the temperature of the second heating strip based on the temperature detected by the fourth thermocouple.

7. The heating rod as described in claim 6, characterized in that, It has a plurality of the first thermocouples arranged in a manner surrounding the first cylindrical body portion.

8. The heating rod as described in claim 1, characterized in that, It also includes a gas passage, which is built into the first cylindrical body and the second cylindrical body in a manner parallel to the axial direction of the second cylindrical body and extends through the ends of the first cylindrical body and the second cylindrical body.

9. The heating rod according to claim 8, characterized in that, It also includes a gas channel inlet, which is located on one end side of the first cylindrical body portion and communicates with the gas channel; and a gas channel outlet, which is located on one end side of the second cylindrical body portion and communicates with the gas channel.

10. The heating rod according to claim 5, characterized in that, It also includes an overheat protection switch, which controls the first temperature controller and / or the second temperature controller to shut down when the temperature of the first cylindrical body portion and / or the second cylindrical body portion exceeds a first predetermined threshold.

11. The heating rod according to claim 6, characterized in that, It also includes an overheat protection switch, which controls the third thermostat and / or the fourth thermostat to shut down when the temperature of the first heating strip and / or the second heating strip exceeds a second predetermined threshold.

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