CN221225927U - Cooling system and superconducting magnetic resonance imaging apparatus - Google Patents

Abstract

The present disclosure relates to a cooling system and a superconducting magnetic resonance imaging apparatus. A cooling system according to the present disclosure includes: the low-temperature refrigerator is provided with a first-stage cold head and a second-stage cold head; a sleeve for receiving the first stage coldhead and the second stage coldhead; wherein at least one of the first stage coldhead and the second stage coldhead is resiliently supported on the sleeve. By the embodiment of the disclosure, good thermal contact between the two-stage cold head and the sleeve can be realized, so that efficient heat transfer between the cold head and the sleeve is realized.

Description

Cooling system and superconducting magnetic resonance imaging apparatus

Technical Field

The present disclosure relates to the technical field of medical instruments, and in particular to a cooling system and a superconducting magnetic resonance imaging apparatus including the same.

Background

As a high-quality imaging device, the position of a superconducting magnetic resonance imaging device in the field of image diagnosis is becoming more and more important. The superconducting magnetic resonance imaging equipment is used as high-precision equipment, and not only relates to the medical physical and chemical technology, the optical conduction technology, the electronic calculation and the precision instrument manufacturing technology, but also relates to the low-temperature refrigeration technology.

A stable cryorefrigeration system is extremely important for superconducting magnetic resonance imaging devices. In general, an alloy coil, which is made of a superconducting magnet, generates a strong magnetic field by passing a current of several hundred amperes in an ultra-low temperature environment. The magnetic field can exist for a long time without providing additional current as long as the low temperature operating environment of the superconducting coil is maintained. However, when the temperature of the superconducting coil increases beyond 10K, resistance is generated, and thus a quench phenomenon occurs. A strong quench may result in damage to the superconducting coil and magnet. Therefore, the superconducting coil is in a stable ultralow temperature environment, which is a necessary condition for the normal operation of the superconducting magnetic resonance imaging device.

The approaches described in this section are not necessarily approaches that have been previously conceived or pursued. Unless otherwise indicated, it should not be assumed that any of the approaches described in this section qualify as prior art merely by virtue of their inclusion in this section. Similarly, the problems mentioned in this section should not be considered as having been recognized in any prior art unless otherwise indicated.

Disclosure of utility model

In view of this, a first aspect of the present disclosure proposes a cooling system comprising: the low-temperature refrigerator is provided with a first-stage cold head and a second-stage cold head; a sleeve for receiving the first stage coldhead and the second stage coldhead; wherein at least one of the first stage coldhead and the second stage coldhead is resiliently supported on the sleeve.

In the above aspect, it is preferable that at least one of the first stage coldhead and the second stage coldhead is elastically supported on the sleeve by an intermediate assembly including a flexible heat conductive member, an elastic member, and a heat conductive block at an end of the flexible heat conductive member.

In the above aspect, it is preferable that the flexible heat conductive member and the elastic member are fixedly connected between the first stage coldhead or the second stage coldhead and the heat conductive block.

In the above aspect, preferably, the flexible heat conducting member and the elastic member are fixedly connected between a first portion of the sleeve for supporting the first stage cold head or a second portion of the sleeve for supporting the second stage cold head and the heat conducting block.

In the above aspect, it is preferable that the cryocooler has a first flange, the sleeve has a second flange at an opening for accommodating the cryocooler, the first flange and the second flange are connected by at least one fastener, and a gap between the first flange and the second flange is adjustable by the fastener.

In the above aspect, preferably, the sleeve includes a first sleeve portion for accommodating the first stage coldhead, a second sleeve portion for accommodating the second stage coldhead, and a stepped portion between the first sleeve portion and the second sleeve portion, the stepped portion serving as the first portion for supporting the first stage coldhead, and a bottom portion of the second sleeve portion serving as the second portion for supporting the second stage coldhead.

In the above aspect, it is preferable that the elastic member is disposed on the bottom of the second sleeve portion and supports the heat conduction block, and the heat conduction block and the bottom of the second sleeve portion are connected via the flexible heat conduction member so that the second-stage coldhead can be in thermal contact with the bottom of the second sleeve portion via the heat conduction block and the flexible heat conduction member, and the fastener is configured to be able to adjust a gap between the first flange and the second flange to bring the first-stage coldhead into thermal contact with the step portion.

In the above aspect, it is preferable that one ends of the elastic member and the flexible heat conductive member are connected to the second stage coldhead, the other ends are connected to the heat conductive block for abutting on the bottom of the second sleeve portion, so that the elastic member can support the second stage coldhead and the second stage coldhead can be in thermal contact with the bottom of the second sleeve portion via the heat conductive block and the flexible heat conductive member, and the fastener is configured to be able to adjust a gap between the first flange and the second flange to bring the first stage coldhead into thermal contact with the stepped portion.

In the above aspect, it is preferable that the elastic member is disposed on the step portion and supports the heat conduction block so that the heat conduction block can be brought into contact with the first stage coldhead, and the heat conduction block and the step portion are connected via the flexible heat conduction member so that the first stage coldhead can be brought into thermal contact with the step portion via the heat conduction block and the flexible heat conduction member, and the fastener is configured to be able to adjust a gap between the first flange and the second flange so as to bring the second stage coldhead into thermal contact with a bottom of the second sleeve portion.

In the above aspect, it is preferable that one ends of the elastic member and the flexible heat conductive member are connected to the first stage coldhead, and the other ends are connected to the heat conductive block for abutting against the stepped portion, so that the elastic member can support the first stage coldhead and the first stage coldhead can be in thermal contact with the stepped portion via the heat conductive block and the flexible heat conductive member, and the fastener is configured to be able to adjust a gap between the first flange and the second flange to bring the second stage coldhead into thermal contact with a bottom of the second sleeve portion.

A second aspect of the present disclosure proposes another cooling system comprising: the low-temperature refrigerator is provided with a first-stage cold head and a second-stage cold head; a sleeve for receiving the first stage coldhead and the second stage coldhead; wherein a first portion of the sleeve for supporting the first stage coldhead is resiliently connected to a second portion of the sleeve for supporting the second stage coldhead.

In the above aspect, preferably, the sleeve includes a first sleeve portion for accommodating the first stage coldhead, a second sleeve portion for accommodating the second stage coldhead, and a stepped portion between the first sleeve portion and the second sleeve portion, the stepped portion serving as the first portion for supporting the first stage coldhead, and a bottom portion serving as the second portion for supporting the second stage coldhead, wherein a side wall of the second sleeve portion is a flexible member.

In the above aspect, preferably, an elastic member is further provided between the step portion and the bottom portion of the second sleeve portion.

A third aspect of the present disclosure proposes a superconducting magnetic resonance imaging apparatus comprising a cooling system according to the first aspect of the present disclosure or a cooling system according to the second aspect of the present disclosure.

By the embodiment of the disclosure, good thermal contact between the two-stage cold head and the sleeve can be realized, so that efficient heat transfer between the cold head and the sleeve is realized.

It should be understood that the description in this section is not intended to identify key or critical features of the embodiments of the disclosure, nor is it intended to be used to limit the scope of the disclosure. Other features of the present disclosure will become apparent from the following specification.

Drawings

The above and other features and advantages of the present disclosure will become more apparent to those of ordinary skill in the art by describing in detail embodiments thereof with reference to the attached drawings, in which:

FIG. 1 shows a schematic diagram of a cooling system of a cryocooler having a two-stage coldhead in accordance with the related art;

FIG. 2A illustrates a schematic view of a cooling system in an assembled initial state according to one embodiment of the present disclosure;

FIG. 2B shows a schematic view of the cooling system of the embodiment of FIG. 2A in an assembled state, according to the present disclosure;

FIG. 3A illustrates a schematic view of a cooling system in an assembled initial state according to one embodiment of the present disclosure;

FIG. 3B illustrates a schematic view of the cooling system of the embodiment of FIG. 3A in an assembled state, according to the present disclosure;

FIG. 4A shows a schematic view of a cooling system in an assembled initial state according to one embodiment of the present disclosure;

FIG. 4B shows a schematic view of the cooling system of the embodiment of FIG. 4A in an assembled state, according to the present disclosure;

FIG. 5A shows a schematic view of a cooling system in an assembled initial state according to one embodiment of the present disclosure;

FIG. 5B shows a schematic view of the cooling system of the embodiment of FIG. 5A in an assembled state according to the present disclosure; and

FIG. 6 illustrates a schematic diagram of a cooling system according to one embodiment of the present disclosure.

Reference numerals illustrate:

10 low-temperature refrigerator

110 First stage coldhead 110

120 Second stage coldhead 120

130 First flange 130

20 Sleeve

210 Step portion

230 Second flange

240 First sleeve portion

250 Second sleeve portion

220 Bottom of the second sleeve portion

30 Intermediate assembly

310 Flexible heat conducting component

320 Elastic member

330 Heat conduction block

340 Corrugated pipe

400 Fastener

610 Indium gasket

630 Thermal radiation shield

640 Superconducting coil

Detailed Description

For a clearer understanding of the technical features, objects, and effects of the present disclosure, specific embodiments of the disclosure will now be described with reference to the drawings in which like reference numerals represent like parts throughout the several views.

In this document, "schematic" means "serving as an example, instance, or illustration," and any illustrations, embodiments described herein as "schematic" should not be construed as a more preferred or advantageous solution.

In the present disclosure, the use of the terms "first," "second," and the like to describe various elements is not intended to limit the positional relationship, timing relationship, or importance relationship of the elements, unless otherwise indicated, and such terms are merely used to distinguish one element from another. In some examples, a first element and a second element may refer to the same instance of the element, and in some cases, they may also refer to different instances based on the description of the context.

In this disclosure, the terminology used in the description of the various examples is for the purpose of describing particular examples only and is not intended to be limiting. Unless the context clearly indicates otherwise, the elements may be one or more if the number of the elements is not specifically limited. Furthermore, the term "and/or" as used in this disclosure encompasses any and all possible combinations of the listed items.

It should be noted that the directional indications (such as up, down, left, right, front, and rear) in the embodiments of the present disclosure are merely used to explain the relative positional relationship, movement conditions, and the like between the components in a certain specific posture (as shown in the drawings), and if the specific posture is changed, the directional indications are correspondingly changed.

In this disclosure, unless specifically stated and limited otherwise, the terms "connected," "affixed," and the like are to be construed broadly, and for example, "affixed" may be a fixed connection, a removable connection, or an integral body. "coupled" may be mechanical or electrical; either directly or indirectly, through intermediaries, or both, may be in communication with each other or in interaction with each other, unless expressly defined otherwise. The specific meaning of the terms in this disclosure will be understood by those of ordinary skill in the art as the case may be.

Conventional superconducting magnets operate at low temperatures, typically below 20K. The portion of the system that is maintained at this temperature may be referred to as the "cold mass". The magnet cold body is enclosed in a vacuum chamber which is substantially at ambient temperature, e.g. 300K. Cryocoolers may be used to maintain the superconducting magnet at the operating temperature of the superconducting magnet, but cryocoolers have limited cooling power at that temperature. In order to reduce radiant heat rushing from the vacuum chamber into the magnet cold body, a thermally conductive heat radiation shield (e.g., a cold screen, which may directly reduce heat radiation conduction) is typically interposed between the vacuum chamber and the magnet cold body. The shield is typically cooled by the first stage coldhead of the cryocooler to a temperature of approximately 50K. The thermal radiation received from the thermal radiation shield at 50K is much less than the thermal radiation that would be received from the vacuum chamber at 300K. The second stage cold head of the cryocooler cools the superconducting coil in a solid conduction manner.

Fig. 1 shows a schematic diagram of a cooling system of a cryocooler having a two-stage cold head in the related art.

The cooling system comprises a cryocooler 10 and a jacket 20. Cryocooler 10 includes a first stage coldhead 110 and a second stage coldhead 120. The sleeve 20 includes a first sleeve portion 240 for receiving the first stage coldhead 110, a second sleeve portion 250 for receiving the second stage coldhead 120, and a stepped portion 210 between the first sleeve portion 240 and the second sleeve portion 250. The step 210 generally serves as a first location for supporting the first stage coldhead 110, and the step 210 generally is in thermal contact with the thermal radiation shield 630. The bottom 220 of the second sleeve portion serves as a second location for supporting the second stage coldhead 120. The bottom 220 of the second sleeve portion is typically thermally connected to a heat exchanger exposed to gaseous cryogen within a cryogen (e.g., helium) vessel to cool the superconducting coil 640. In some arrangements, the heat exchanger is directly exposed to the interior of the cryogen vessel.

During assembly of the cooling system, the first flange 130 of the cryocooler 10 is connected, for example by bolts, to the second flange 230 of the sleeve at the opening for receiving the cryocooler, and the gap between the first flange 130 and the second flange 230 can be adjusted by bolts to bring one of the primary coldheads into thermal contact with the corresponding sleeve location. However, by means of the adjusting screw, only the thermal contact between one of the primary cooling heads and the corresponding sleeve part, for example between the primary cooling head 110 and the stepped portion 210 of the sleeve, can be ensured. Thermal contact between another coldhead and a corresponding sleeve portion, such as thermal contact between the second stage coldhead 120 and the bottom 220 of the second sleeve portion, cannot be ensured due to over-constraint in the vertical direction. It is understood that in this context, "thermal contact" may refer to direct thermal contact, as well as indirect thermal contact via other media.

In the related art, in order to achieve thermal contact between the two-stage coldhead and the respective corresponding sleeve portions, an indium gasket 610 is generally mounted between the first-stage coldhead 110 and the stepped portion 210 of the sleeve, and between the second-stage coldhead 120 and the bottom portion 220 of the second sleeve portion, respectively, of the cryocooler 10 to accommodate manufacturing tolerances and assembly tolerances of the respective components. The tolerance between the coldhead and the sleeve is absorbed by the deformation caused by the compression of the indium gasket. This deformation of the indium gasket typically requires a high pressure, and the upper and lower wall tubes of the coldhead, sleeve, etc. in the cooling system are typically thin and cannot withstand the high pressure. Thus, this approach tends to sacrifice some contact area to ensure deformation. Even if good machining accuracy and proper pressure can be provided to ensure good thermal contact at the state of the art, the contact area that can be provided by the indium gasket is still small.

In order to achieve a good cooling of the 50K shield and the cold body, it is necessary to achieve a good thermal contact between the two-stage coldhead and the sleeve. As described above, the current installation method of fixing the cold head by bolts can only ensure the thermal contact between the cold head of one stage and the sleeve, and at the cold head of the other stage, it is generally difficult to ensure good thermal contact due to the over-constraint problem in the vertical direction. While the use of deformable indium washers tends to sacrifice some contact area.

In view of this, embodiments of the present disclosure provide a cooling system and a superconducting magnetic resonance imaging apparatus including the cooling system. Manufacturing and assembly tolerances are absorbed by providing resilient members between a certain level of coldhead and a corresponding part of the sleeve, or between parts of the sleeve for supporting the two levels of coldhead, so that good thermal contact between the sleeve and the two levels of coldhead is achieved and sufficient heat transfer area is enabled.

According to a first aspect of the present disclosure, a cooling system is provided. The cooling system comprises a cryocooler 10 and a jacket 20. Cryocooler 10 has a first stage coldhead 110 and a second stage coldhead 120. The sleeve 20 is configured to receive the first stage coldhead 110 and the second stage coldhead 120. Wherein at least one of the first stage coldhead 110 and the second stage coldhead 120 is resiliently supported on the sleeve 20.

Cryocoolers provide active refrigeration to cool a cryogen gas within a cryogen vessel, in some arrangements by re-condensing the cryogen gas (e.g., helium) into a liquid. Cryocoolers may also be used to cool the radiation shield. Typically, the first stage coldhead of the cryocooler is thermally coupled to the radiation shield and provides cooling to a first temperature in the range of 50-80K. The second stage coldhead provides cooling to a second temperature of about 4K to provide helium recondensing.

According to the embodiment of the present disclosure, by elastically supporting at least one of the first stage coldhead 110 and the second stage coldhead 120 on the sleeve 20, the other stage of coldhead can be abutted with the corresponding part of the sleeve by the elastic member with the contact of the other stage of coldhead with the corresponding part of the sleeve, thereby achieving the purpose of eliminating or adapting to manufacturing and assembly tolerances. Therefore, the two-stage cold head in the liquid helium-free magnet cooling system can simultaneously cool the cold screen and the coil through heat conduction, so that the stable operation of the magnet is maintained.

In some embodiments, at least one of the first stage coldhead 110 and the second stage coldhead 120 is resiliently supported on the sleeve 20 by an intermediate assembly 30, the intermediate assembly 30 including a flexible thermally conductive member 310, a resilient member 320, and a thermally conductive block 330 at an end of the flexible thermally conductive member 310.

The flexible heat conductive member 310 may be, for example, a metal heat conductive tape such as a copper tape, an aluminum tape, or any other metal tape having good heat conductivity and ductility. The flexible heat conductive member 310 may be woven in a band shape or a strip shape from a metal wire, and both ends are provided with through holes so that both ends thereof may be mounted on other heat conductive members via fasteners such as screws. In some embodiments, a flexible heat conducting member is connected between the coldhead and the sleeve, the flexible heat conducting member being capable of ensuring good heat transfer between the coldhead and the sleeve. The number of flexible heat conductive members 310 may be one or more, for example, a plurality of strip-shaped or strip-shaped flexible heat conductive members 310 are circumferentially disposed. Further, by providing the length at which the flexible heat conductive member 310 is flexibly connected to other heat conductive members, it is possible to make it free from the restriction of the elastic movement of the elastic member, for example.

The elastic member 320 may be, for example, a spring, a member of elastomeric material, or any other member capable of providing elastic deformation. The number of elastic members 320 may be one or more. In some embodiments, the resilient member 320 may provide a certain resilient contact force to ensure good thermal contact between the coldhead and the sleeve supporting it.

The heat conductive block 330 may be, for example, a metal block or a metal ring. The metal may be any metal that is capable of good heat conduction, such as copper.

Fig. 2A and 2B show schematic views of a cooling system according to an embodiment of the present disclosure in an initial assembled state and a completed assembled state, respectively.

As shown in fig. 2A and 2B, the cooling system includes a cryocooler and a jacket. Cryocooler 10 has a first stage coldhead 110 and a second stage coldhead 120, with a sleeve 20 for receiving first stage coldhead 110 and second stage coldhead 120, wherein second stage coldhead 120 is configured to be resiliently supported on sleeve 20, first stage coldhead 110 being configured for direct thermal contact with sleeve 20, for example. Specifically, the sleeve 20 includes a first sleeve portion 240 for accommodating the first stage coldhead 110, a second sleeve portion 250 for accommodating the second stage coldhead 120, and a stepped portion 210 between the first sleeve portion 240 and the second sleeve portion 250, the stepped portion 210 serving as a first location for supporting the first stage coldhead 110, and a bottom portion 220 of the second sleeve portion serving as a second location for supporting the second stage coldhead 120. By having the second stage coldhead 120 resiliently supported on the sleeve 20, manufacturing and installation tolerances of each stage coldhead can be compensated for, ensuring that both the first stage coldhead and the second stage coldhead are in good thermal contact with the sleeve 20.

As shown in fig. 2A and 2B, the second stage coldhead 120 is resiliently supported on the sleeve 20 by the intermediate assembly 30. The intermediate assembly 30 comprises a flexible heat conducting member 310, an elastic member 320 and a heat conducting block 330, wherein the flexible heat conducting member 310 and the elastic member 320 are fixedly connected between a second portion of the sleeve for supporting the second stage coldhead (i.e., the bottom 220 of the second sleeve portion in the embodiment shown in fig. 2A and 2B) and the heat conducting block. Specifically, the elastic member 320 is disposed on the bottom 220 of the second sleeve part 250 and supports the heat conductive block 330, and the heat conductive block 330 is connected with the bottom 220 of the second sleeve part via the flexible heat conductive member 310. The flexible heat conducting member 310 comprises, for example, a copper strap or braid having one end connected to the heat conducting block 330, for example, to the bottom of the heat conducting block 330, and the other end connected to the bottom 220 of the second sleeve portion. The number of the flexible heat conductive members 310 may be plural to ensure heat conduction between the heat conductive block 330 and the sleeve. The heat conductive block 330 may be a cylindrical metal block configured to have a diameter as large as possible so that a gap between the heat conductive block 330 and the second sleeve part 250 is as small as possible. The elastic member 320 may be a spring having a large diameter provided between the metal block and the center of the bottom 220 of the second sleeve part, and the heat conductive metal block may be maintained in a horizontal state to avoid tilting by setting the diameter of the spring to be sufficiently large and making the gap between the heat conductive block 330 and the second sleeve part 250 as small as possible. In other embodiments, the elastic member may also be a plurality of springs circumferentially uniformly arranged between the bottom 220 of the second sleeve part and the heat conductive block 330 around the center of the heat conductive block 330 or the bottom 220 of the second sleeve part. The large-diameter elastic member and the plurality of elastic members are provided so that the heat conductive block 330 is stably supported to prevent the heat conductive block 330 from tilting when the elastic members are compressed.

As shown in fig. 2A and 2B, the cryocooler 10 has a first flange 130, the sleeve 20 has a second flange 230, the first flange 130 and the second flange 230 are connected by at least one fastener 400 by which a gap between the first flange and the second flange can be adjusted. The first flange 130 is disposed on a side of the first stage coldhead 110 opposite the second stage coldhead 120. The second flange 230 is disposed at an opening of the sleeve 20 for receiving the cryocooler 10. The second flange 230 may be integrally connected with the sleeve portion of the sleeve 20 and, for example, have a size not smaller than the first flange 130. The gap between the first flange 130 and the second flange 230 may be adjusted by bolts and nuts, or similar mechanical fasteners 400, to provide a controllable clamping force between the coldhead and the corresponding components of the sleeve. Fastener 400 may be loosened or tightened when removal or installation of the cryocooler is desired. The number of fasteners 400 may be one or more, such as 3 or more. By uniformly arranging, for example, 3 bolts, the first flange 130 and the second flange 230 can be stably fixed.

In some embodiments, the sleeve includes fixedly connected portions, such as a second flange, a first sleeve portion, a stepped portion, a second sleeve portion, and a bottom portion thereof. The various parts of the sleeve are secured together, for example by welding, to accommodate the first stage coldhead and the second stage coldhead of the cryocooler.

During assembly of the cooling system, after the first stage coldhead and the second stage coldhead of the cryocooler are placed in the sleeve as shown in FIG. 2A, the second stage coldhead 120 is brought against the thermally conductive block 330 and compresses the resilient member 320 downward. For example, by tightening the fastener between the first flange 130 and the second flange 230, which is implemented as a bolt, the second stage coldhead 120 is brought into contact first with the heat conducting block 330 arranged above the resilient member 320, and as the fastener 400 continues to be tightened, the gap between the first flange 130 and the second flange 230 continues to be smaller, the second stage coldhead 120 compresses the spring downwards until the first stage coldhead 110 is brought into good thermal contact with the step 210 as shown in fig. 2B. The elastic member 320 is compressed and applies an opposite elastic force to the heat-conducting block so that good thermal contact can be made between the heat-conducting block 330 and the second stage coldhead 120. Meanwhile, through the flexible heat conducting component 310 arranged between the heat conducting block 330 and the bottom 220 of the second sleeve part, good heat transfer is formed between the heat conducting block 330 and the bottom 220 of the second sleeve part, and further good heat transfer is formed between the second-stage cold head and the bottom 220 of the second sleeve part through the heat conducting block 330 and the flexible heat conducting component 310. In this way, both the first stage coldhead and the second stage coldhead are able to produce good heat transfer with the sleeve 20.

Similar to fig. 1, the stepped portion 210 of the sleeve 20 may be connected to a heat radiation shield 630, and the heat radiation shield 630 may be cooled by a first stage coldhead 110 in thermal contact with the stepped portion 210. The bottom 220 of the second sleeve part may be connected to a superconducting coil, which may be cooled by the second stage coldhead 120 thermally and elastically supported on the bottom 220 of the second sleeve part.

According to the cooling system of the embodiment of the present disclosure, after the axial force provided by the fastener ensures good thermal contact between the cold head of one stage and the corresponding portion of the sleeve, the thermal contact of the cold head of the other stage and the sleeve can be ensured by the heat transfer of the flexible heat transfer member and the elastic force generated by the compression elastic member. This improvement requires only minor structural changes to the existing mechanical structure of the coldhead and sleeve and can be readily manufactured by suppliers familiar with the existing structure. Additional intermediate parts (e.g. resilient parts and flexible heat conducting parts) are also readily available and can be fixed by simple welding or screws. In addition, the replacement of the coldhead or sleeve may be accomplished during the manufacturing process, thus not significantly affecting the assembly process of the magnet production, and not adding additional effort to the production line.

Fig. 3A and 3B are schematic views showing a cooling system according to another embodiment of the present disclosure in an initial state of assembly and a completed state of assembly, respectively. Similar to the embodiment shown in fig. 2A and 2B, in the embodiment shown in fig. 3A and 3B, the second stage coldhead 120 of the cryocooler 10 is configured to be resiliently supported on the sleeve 20, with the first stage coldhead 110 being configured in thermal contact with the sleeve 20, for example.

Unlike the embodiment shown in fig. 2A and 2B, in the embodiment shown in fig. 3A and 3B, the intermediate assembly 30 is fixedly connected to the second stage coldhead 120, rather than to the bottom 220 of the second sleeve portion. Referring to fig. 3A, the flexible heat conductive member 310 and the elastic member 320 of the intermediate assembly are fixedly connected between the second stage coldhead 120 and the heat conductive block 330. The elastic member 320 and the flexible heat conductive member 310 have one end connected to the second stage coldhead 120 and the other end connected to the heat conductive block 330. The heat conducting block 330 is adapted to rest on the bottom 220 of the second sleeve part such that the resilient member 320 is capable of supporting the second stage coldhead 120 and the second stage coldhead 120 is capable of heat transfer with the bottom 220 of the second sleeve part via the heat conducting block 330 and the flexible heat conducting member 310. The fastener 400 is configured to adjust the gap between the first flange 130 and the second flange 230 to bring the first stage coldhead 110 into thermal contact with the step 210.

Referring to fig. 3A and 3B, after the first stage coldhead and the second stage coldhead of the cryocooler are placed into the sleeve 20 as shown in fig. 3A, the second stage coldhead 120 is compressed downwardly to compress the spring, for example, by adjusting the fasteners 400 between the first flange 130 and the second flange 230, until the first stage coldhead 110 is in good thermal contact with the step 210 as shown in fig. 3B. Good thermal contact can also be made between the heat conducting block 330 and the bottom part 220 of the second sleeve part by the elastic force exerted by the compressed elastic member 320 on the heat conducting block 330. While flexible thermally conductive member 310 is provided to provide good heat transfer between thermally conductive block 330 and second stage coldhead 120.

Notably, the cooling system shown in fig. 3A and 3B is easier to maintain due to the location where the intermediate components (e.g., flexible thermally conductive member 310, resilient member 320, and thermally conductive block 330) are disposed. Specifically, in the present embodiment, the elastic member 320 and the flexible heat conductive member 310 are fixedly connected to the bottom of the second stage coldhead 120 and connected to the heat conductive block 330, and when the elastic member 320 needs to be replaced or whether the flexible heat conductive member 310 is loose or not needs to be checked, maintenance can be performed on the elastic member 320 or the flexible heat conductive member 310 by pulling out the cryocooler, thereby reducing the requirements on tools and operations due to the problem of the depth of the sleeve.

Fig. 4A and 4B are schematic views showing a cooling system according to another embodiment of the present disclosure in an initial state of assembly and a completed state of assembly, respectively. Unlike the embodiments described above, in the embodiment shown in fig. 4A and 4B, the first stage coldhead 110 is configured to resiliently support on the sleeve 20 and the second stage coldhead 120 is configured to, for example, be in direct contact with the sleeve 20.

In the embodiment shown in fig. 4A and 4B, the first stage coldhead 110 is resiliently supported by the intermediate assembly 30 on a first portion, i.e., a step 210, of the sleeve 20 for supporting the first stage coldhead 110. The intermediate assembly 30 includes an elastic member 310, a flexible thermally conductive member 320, and a thermally conductive block 330. Wherein the flexible heat conductive member 310 and the elastic member 320 are fixedly coupled between a first portion (i.e., the stepped portion 230 in the embodiment shown in fig. 4A and 4B) of the sleeve for supporting the first stage coldhead and the heat conductive block. Specifically, the elastic member 320 is disposed on the stepped part 210 and supports the heat conductive block 330 such that the heat conductive block 330 can be in contact with the first stage coldhead 110, and the heat conductive block 330 and the stepped part 210 are connected via the flexible heat conductive member 310 such that the first stage coldhead 110 can be in thermal contact with the stepped part 210 via the heat conductive block 330 and the flexible heat conductive member 310. The fastener 400 is configured to adjust the gap between the first flange 130 and the second flange 230 to bring the second stage coldhead 120 into thermal contact with the bottom 220 of the second sleeve portion.

In the embodiment shown in fig. 4A and 4B, the thermally conductive mass 330 is a metal ring having a thickness, wherein the inner diameter of the metal ring is configured to provide an assembly space for the second stage coldhead. Holes or slots may also be provided in the metal ring for securing the ends of the flexible thermally conductive member 310.

In the embodiment shown in fig. 4A and 4B, an elastic member including, for example, a plurality of springs, which may be uniformly arranged circumferentially around the axis of the first stage coldhead 110 between the stepped portion 210 and the heat conductive block 330, is provided, so that the heat conductive block 330 can be stably supported, preventing the heat conductive metal ring from being inclined and pressed to the first stage coldhead when the elastic member 320 is compressed. Further, the heat conductive block 330 is connected with the step 210 via the flexible heat conductive member 310. In the embodiment shown in fig. 5A and 5B, a flexible heat conductive member 310, such as a copper strap, is attached at one end to the bottom of the heat conductive metal ring and at the other end to the inside wall of the step. The number of the flexible heat conductive members 310 may be plural to achieve good heat conduction between the heat conductive block 330 and the stepped portion 210.

During assembly of the cooling system, after the first stage coldhead 110 and the second stage coldhead 120 of the cryocooler are placed into the sleeve 20, the first stage coldhead 110 is pressed down against the resilient member 320 by, for example, tightening the fasteners 400 between the first flange 130 and the second flange 230 until the second stage coldhead 120 is in good thermal contact with the bottom 220 of the second sleeve portion. The first stage coldhead 110 is also able to make good thermal contact with the thermally conductive metallic ring 330 by the spring force exerted by the spring member 320. While a flexible heat conductive member 310 is provided to provide good heat transfer between the first stage coldhead 110 and the step 210.

Fig. 5A and 5B are schematic views showing a cooling system according to another embodiment of the present disclosure in an initial state of assembly and a completed state of assembly, respectively. As shown in fig. 5A and 5B, the first stage coldhead 110 is configured to be resiliently supported on the sleeve 20 and the second stage coldhead 120 is configured to be in direct contact with the sleeve 20, for example.

Referring to fig. 5A and 5B, the intermediate assembly 30 is fixedly coupled to the first stage coldhead 110, rather than to the step 230. Referring to fig. 5A, the flexible heat conductive member 310 and the elastic member 320 of the intermediate assembly are fixedly coupled between the first stage coldhead 110 and the heat conductive block 330. The elastic member 320 and the flexible heat conductive member 310 are connected at one end to the first stage coldhead 110 and at the other end to the heat conductive block 330 for abutting against the step 210 such that the elastic member 320 can support the first stage coldhead 110 and the first stage coldhead 110 can be in thermal contact with the step 210 via the heat conductive block 330 and the flexible heat conductive member 310, and the fastener 400 is configured to be able to adjust the gap between the first flange 130 and the second flange 230 to bring the second stage coldhead 120 into thermal contact with the bottom 220 of the second sleeve portion.

An elastic member 320 such as a spring and a flexible heat conductive member 310 such as a copper tape are connected at one end to the first stage cold head 110, for example, to the peripheral side or upper side of the first stage cold head 110, and at the other end to a heat conductive block 330 abutting against the step 210, for example, to the upper side of the heat conductive block 330. The heat conducting block 330 may be a metal ring having a thickness, wherein an inner diameter of the metal ring is configured to provide an assembly space for the second stage coldhead. Holes or slots may also be provided in the metal ring for securing the ends of the flexible thermally conductive member 310. The elastic members 320 may be uniformly disposed circumferentially around the axis of the first stage coldhead 110 between the first stage coldhead 110 and the thermally conductive metallic ring. The elastic member 320 disposed on the heat conductive metal ring 330 can support the first stage coldhead 110. The number of the flexible heat conductive members 310 may be plural to achieve heat conduction between the heat conductive block 330 and the first stage coldhead 110.

During assembly of the cooling system, after the first stage coldhead 110 and the second stage coldhead 120 of the cryocooler are placed into the sleeve 20 as shown in fig. 5A, the first stage coldhead 110 presses down on the resilient member 320 by, for example, tightening the fasteners 400 between the first flange 130 and the second flange 230 until the second stage coldhead 120 makes good thermal contact with the bottom 220 of the second sleeve portion as shown in fig. 5B. The stepped portion 210 can also be brought into good thermal contact with the heat conductive block 330 by the elastic force applied by the elastic member 320. While providing flexible heat conducting members to provide good heat transfer between the first stage coldhead 110 and the heat conducting block 330.

In addition, the cooling system shown in fig. 5A and 5B is easier to maintain due to the location where the intermediate components (e.g., the flexible heat conductive member 310, the elastic member 320, and the heat conductive block 330) are disposed. Specifically, in the present embodiment, the elastic member 320 and the flexible heat conductive member 310 are fixedly connected to the first stage coldhead 110 and connected to the heat conductive block 330, and when the elastic member 320 needs to be replaced or whether the flexible heat conductive member 310 is loose or not needs to be checked, maintenance can be performed on the elastic member 320 or the flexible heat conductive member 310 by pulling out the cryocooler, thereby reducing the requirements on tools and operations due to the problem of the depth of the sleeve.

According to a second aspect of the present disclosure, another cooling system is provided. The cooling system comprises a cryocooler 10 and a jacket 20. Cryocooler 10 has a first stage coldhead 110 and a second stage coldhead 120. The sleeve 20 is configured to receive the first stage coldhead 110 and the second stage coldhead 120. Wherein a first portion of the sleeve 20 for supporting the first stage coldhead 110 is elastically connected to a second portion of the sleeve 20 for supporting the second stage coldhead 120.

According to the embodiment of the present disclosure, by elastically connecting the first portion of the sleeve 20 for supporting the first stage coldhead 110 to the second portion of the sleeve 20 for supporting the second stage coldhead 120, the abutment of the other stage of the coldhead with the corresponding component of the sleeve can be achieved by the elastic member with the contact of the one stage coldhead with the corresponding portion of the sleeve, thereby achieving the objective of eliminating or accommodating manufacturing and assembly tolerances. Therefore, the two-stage cold head in the liquid helium-free magnet cooling system can simultaneously cool the cold screen and the coil through heat conduction, so that the stable operation of the magnet is maintained.

Fig. 6 shows a schematic diagram of a cooling system according to an embodiment of the second aspect of the present disclosure.

Similar to the embodiment shown in fig. 2A-2B and 3A-3B, the sleeve 20 includes a first sleeve portion 240 for receiving the first stage coldhead 110, a second sleeve portion 250 for receiving the second stage coldhead 120, and a step portion 210 between the first sleeve portion 240 and the second sleeve portion 250, the step portion 210 serving as a first location for supporting the first stage coldhead 110 and the bottom portion 220 of the second sleeve portion serving as a second location for supporting the second stage coldhead 120. Unlike the embodiment shown in fig. 2A-2B and 3A-3B, instead of the second stage coldhead being resiliently supported on the bottom of the second sleeve portion, a first portion of sleeve 20 (such as stepped portion 210 shown in fig. 6) for supporting first stage coldhead 110 is resiliently connected to a second portion of sleeve 20 (such as bottom 220 shown in fig. 6) for supporting second stage coldhead 120. For example, referring to fig. 6, the stepped portion 210 is connected to the bottom portion 220 by an elastic member 320, and the sidewall of the second sleeve portion 250 is a flexible member, such as a bellows 340. By means of the resilient member 320 as well as the flexible member, manufacturing and mounting tolerances of the cold heads of each stage can be compensated for, ensuring good thermal contact of the cold heads of each stage with the sleeve.

During the assembly of the cooling system, after the first stage coldhead 110 and the second stage coldhead 120 of the cryocooler are placed in the sleeve 20, the second stage coldhead 120 is first brought into contact with the bottom 220 of the second sleeve portion and then the bellows 340 and the resilient member 320 are pushed down until the first stage coldhead 110 is in good thermal contact with the step 210. At the same time, the elastic force generated by the compression of the elastic member 320 brings the bottom 220 of the second sleeve portion into good thermal contact with the second stage coldhead 120.

With continued reference to fig. 6, the elastic member 320 may be a plurality of springs circumferentially uniformly arranged on the bottom 220 of the second sleeve part around the center of the bottom 220 of the cold head or the second sleeve part.

According to a third aspect of the present disclosure, there is provided a superconducting magnetic resonance imaging apparatus comprising a cooling system according to the first aspect described above or a cooling system according to the second aspect described above. The features and advantages described above for the cooling system are equally applicable to a superconducting magnetic resonance imaging apparatus. For brevity, certain features and advantages are not described in detail herein.

Although embodiments or examples of the present disclosure have been described with reference to the accompanying drawings, it is to be understood that the foregoing methods, systems, and apparatus are merely exemplary embodiments or examples, and that the scope of the present utility model is not limited by these embodiments or examples but only by the claims following the grant and their equivalents. Various elements of the embodiments or examples may be omitted or replaced with equivalent elements thereof. Furthermore, the steps may be performed in a different order than described in the present disclosure. Further, various elements of the embodiments or examples may be combined in various ways. It is important that as technology evolves, many of the elements described herein may be replaced by equivalent elements that appear after the disclosure.

Claims (14)

1. A cooling system, comprising:

the low-temperature refrigerator is provided with a first-stage cold head and a second-stage cold head;

A sleeve for receiving the first stage coldhead and the second stage coldhead;

Wherein at least one of the first stage coldhead and the second stage coldhead is resiliently supported on the sleeve.

2. The cooling system of claim 1, wherein at least one of the first stage coldhead and the second stage coldhead is resiliently supported on the sleeve by an intermediate assembly comprising a flexible thermally conductive member, a resilient member, and a thermally conductive block at an end of the flexible thermally conductive member.

3. The cooling system of claim 2, wherein the flexible thermally conductive member and the resilient member are fixedly connected between the first stage coldhead or the second stage coldhead and the thermally conductive block.

4. The cooling system of claim 2, wherein the flexible heat-conducting member and the elastic member are fixedly connected between a first portion of the sleeve for supporting the first stage coldhead or a second portion of the sleeve for supporting the second stage coldhead and the heat-conducting block.

5. The cooling system of claim 4, wherein the cryocooler has a first flange and the sleeve has a second flange at an opening for receiving the cryocooler, the first flange and the second flange being connected by at least one fastener by which a gap between the first flange and the second flange can be adjusted.

6. The cooling system of claim 5, wherein the sleeve includes a first sleeve portion for receiving the first stage coldhead, a second sleeve portion for receiving the second stage coldhead, and a step portion between the first sleeve portion and the second sleeve portion, the step portion serving as the first location for supporting the first stage coldhead, and a bottom portion of the second sleeve portion serving as the second location for supporting the second stage coldhead.

7. The cooling system of claim 6, wherein the resilient member is disposed on the bottom of the second sleeve portion and supports the heat-conducting block, and the heat-conducting block and the bottom of the second sleeve portion are connected via the flexible heat-conducting member such that the second stage coldhead is thermally contacted with the bottom of the second sleeve portion via the heat-conducting block and the flexible heat-conducting member, and

The fastener is configured to adjust a gap between the first flange and the second flange to bring a first stage coldhead into thermal contact with the step.

8. The cooling system of claim 6, wherein the elastic member and the flexible heat-conducting member are connected at one end to the second stage coldhead and at the other end to the heat-conducting block for abutting against the bottom of the second sleeve portion, such that the elastic member can support the second stage coldhead and the second stage coldhead can be in thermal contact with the bottom of the second sleeve portion via the heat-conducting block and the flexible heat-conducting member, and

The fastener is configured to adjust a gap between the first flange and the second flange to bring the first stage coldhead into thermal contact with the step.

9. The cooling system according to claim 6, wherein the elastic member is arranged on the step portion and supports the heat-conducting block so that the heat-conducting block can be brought into contact with the first-stage coldhead, and the heat-conducting block and the step portion are connected via the flexible heat-conducting member so that the first-stage coldhead can be brought into thermal contact with the step portion via the heat-conducting block and the flexible heat-conducting member, and

The fastener is configured to adjust a gap between the first flange and the second flange to bring the second stage coldhead into thermal contact with a bottom of the second sleeve portion.

10. The cooling system according to claim 6, wherein one end of the elastic member and the flexible heat conductive member is connected to the first stage coldhead, and the other end is connected to the heat conductive block for abutting against the step portion, such that the elastic member can support the first stage coldhead and the first stage coldhead can be in thermal contact with the step portion via the heat conductive block and the flexible heat conductive member, and

The fastener is configured to adjust a gap between the first flange and the second flange to bring the second stage coldhead into thermal contact with a bottom of the second sleeve portion.

11. A cooling system, comprising:

the low-temperature refrigerator is provided with a first-stage cold head and a second-stage cold head;

A sleeve for receiving the first stage coldhead and the second stage coldhead;

wherein a first portion of the sleeve for supporting the first stage coldhead is resiliently connected to a second portion of the sleeve for supporting the second stage coldhead.

12. The cooling system of claim 11, wherein the sleeve includes a first sleeve portion for receiving the first stage coldhead, a second sleeve portion for receiving the second stage coldhead, and a step portion between the first sleeve portion and the second sleeve portion, the step portion serving as the first location for supporting the first stage coldhead, a bottom portion of the second sleeve portion serving as the second location for supporting the second stage coldhead, wherein a sidewall of the second sleeve portion is a flexible member.

13. The cooling system of claim 12, wherein a resilient member is further disposed between the stepped portion and the bottom of the second sleeve portion.

14. A superconducting magnetic resonance imaging apparatus comprising a cooling system according to any one of claims 1 to 13.