Field of the Invention

The present invention relates to magnetic resonance imaging, and more particularly to a heat conducting device, a cooling apparatus, and a corresponding magnetic resonance system.

Background of the Invention

Magnetic resonance imaging is a biomagnetism nuclear spin imaging technology developed rapidly with the development of the computer technology, electronic circuit technology, and superconductor technology. In magnetic resonance imaging, human tissue is placed in a static magnetic field B ₀ ; then, a radio frequency pulse having the same frequency as the precession frequency of hydrogen nuclei is used to excite hydrogen nuclei in the human tissue to cause the hydrogen nuclei to resonate and absorb energy; after the radio frequency pulse is stopped, the hydrogen nuclei emit radio signals at a specific frequency and release the absorbed energy, and the radio signals are recorded by an external receiver and processed by a computer to obtain an image.

Since a commercial Gifford McMahon (GM) cold head can provide a strong cooling capacity to recondense helium gas of a superconducting magnet of a magnetic resonance system, heat exchange between the GM cold head and the superconducting magnet of the magnetic resonance system has become the key technology to achieve zero loss of helium gas.

In order to use the GM cold head to cool the superconducting magnet successfully, it is necessary to establish an effective thermal connection between the GM cold head and the superconducting magnet so as to improve the heat conductivity between the GM cold head and the superconducting magnet to the maximum extent. The heat conduction performance is usually related to two factors: the purity of the heat conducting material and the connection mode of nodes.

Typically, heat conducting devices in the superconducting magnet of the magnetic resonance system are located between a cold head and a cooled object or between cooled objects. In an example magnet having zero cryogen loss, the heat conducting device may connect a first-stage of a cold head to a thermal shielding layer, a current lead, etc.; in other magnets, the heat conducting device may connect two thermal shielding layers.

Currently, the heat conducting device usually uses one or more flexible braids or laminates of one or more flexible sheets, usually of copper or aluminum, placed in parallel. Such heat conducting devices are typically used to establish a heat conductive connection between the cold head and the cooled object or between cooled objects. The heat conducting device is usually connected to the cold head or the cooled object by screws, or bolted joints. However, such heat conducting devices have disadvantages of small thermal contact area and easy deformation under high moment of the screws, bolts or nuts. Therefore, such heat conducting devices have high heat resistance. Meanwhile, to achieve better heat conductivity between the heat conducting device and the connected objects, a soft, heat conducting material, e.g., an indium film or conductive grease, may be applied to an interface.

Furthermore, in order to achieve better heat conductivity, heat conduction is implemented by contact between panels. One or more flexible braids or one or more flexible sheets (usually of copper or aluminum) are welded on a rigid panel, so as to establish heat conduction between the braid or sheet of the heat conducting device and the panel of the heat conducting device, and then heat conduction is performed between the panel of the heat conducting device and a panel of a target object. However, in the above connection mode, the welding process is complicated and time-consuming and has high requirements for the treatment process, resulting in high manufacturing cost. Summary of the Invention

In view of the above technical problems, in order to achieve excellent heat conduction effect of a heat conducting device through a simple and inexpensive treatment process, the present invention provides a heat conducting device, including a flexible component and a first rigid component, in which one end of the flexible component is connected to the first rigid component by a stamping method.

Meanwhile, the present invention further provides a cooling apparatus, including a cold head and the above heat conducting device, in which the heat conducting device is connected to a thermal coupling member of the cold head.

Meanwhile, the present invention further provides a magnetic resonance system, including the above heat conducting device, a cold head, and a superconducting magnet, in which the heat conducting device is connected between a thermal coupling member of the cold head and a thermal shielding layer of the superconducting magnet.

According to the above technical solutions, the heat conducting device is manufactured by a stamping method, a simple process and excellent heat conductivity are achieved, and the cost can be saved with the same effect.

Brief Description of the Drawings

Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings so that persons of ordinary skill in the art can understand the foregoing and other features and advantages of the present invention more clearly. In the accompanying drawings:

FIG. 1A and FIG. IB are side sectional views of a heat conducting device according to a specific embodiment of the present invention.

FIG. 2A and FIG. 2B are schematic views of the heat conducting device according to the specific embodiment of the present invention.

FIG. 3A and FIG. 3B are schematic views illustrating connection between the heat conducting device according to a specific embodiment of the present invention and a cold head and a cooled object.

FIG. 4 is a schematic view of a cooling apparatus according to a specific embodiment of the present invention. The following features are labeled in the drawings: heat conducting device 100 rigid component 101 flexible component 102 such as a flexible braid or laminate cold head 200 thermal coupling member 201 thermal shielding layer 301

Detailed Description of the Preferred Embodiments

In order to make the objectives, technical solutions, and advantages of the present invention clearer, embodiments are provided below to further illustrate the present invention in detail.

FIG. 1A and FIG. IB are side sectional views of a heat conducting device according to a specific embodiment of the present invention. As shown in FIG. 1A and FIG. IB, according to a specific embodiment of the present invention, a heat conducting device includes a rigid component 101 and a flexible component 102. A recess is provided on one side of the rigid component 101, one end of the flexible component 102 extends into the recess, and the joint part (i.e., the recess part) of the rigid component and the flexible component is stamped from the outside in a direction perpendicular to the contact surface between the rigid component and a cooled object, so as to connect the rigid component 101 and the flexible component 102. FIG. 1 A shows the heat conducting device according to a specific embodiment of the present invention using single-sided stamping 100, and FIG. IB shows the heat conducting device according to a first specific embodiment of the present invention using double-sided stamping 100. Specifically, FIG. 2A and FIG. 2B are schematic views of the heat conducting device according to a specific embodiment of the present invention. As shown in FIG. 2A and FIG. 2B, in the heat conducting device according to the specific embodiment of the present invention, the rigid component 101 is a panel; the flexible component 102 is one or more braids arranged in parallel and/or one or more laminates arranged in parallel, and may also be one or more braids arranged in a staggered manner and/or one or more laminates arranged in parallel. In the heat conducting device according to the specific embodiment of the present invention, the stamping method used for connection between the flexible component and the rigid component is a non-welding process, that is, the braid or the laminate is connected to the panel through mechanical pressure completely, and the method that can be used includes cold rolling, cold breakdown, and cold forging. As shown in FIG. 2A, the braid may be connected to the panel by multi-point stamping: an individual stamping location for each braid or laminate. Alternatively, the braid or the laminate may be connected to the panel by row-by-row stamping, as shown in Fig. 2B, where one or more elongate stamping location may be applied to all, or subsets, of the braids and/or laminates. In alternative embodiments, the stamping may be applied from one side only, as visible in Figs. 2A, 2B; alternatively, stamping may be applied simultaneously on opposite sides of the braids or laminates. In a particular series of embodiments, one side of the braids or laminates may be stamped with an individual stamping location for each braid or laminate while the other side has one or more elongate stamping location applied to all, or subsets, of the braids and/or laminates. The material of the flexible component and the rigid component is a material of high heat conductivity, e.g., copper or aluminum. A similar arrangement and method may be applied at the other end of the flexible component 102.

To make the heat resistance between the flexible component and the rigid component connected by stamping as small as possible, various components of the heat conducting device according to the specific embodiment of the present invention are cleaned before assembly. The specific process used will depend on the materials involved, but may include deoxidizing the flexible component and the rigid component, in which a deoxidizing agent may be used dissolved in water or alcohol, and the flexible component and the rigid component are immersed in the solution. Preferably, the heat conducting device is assembled within 5 hours after the end of the cleaning to prevent recurrence of surface contamination.

Compared with the contact between a single braid or a single laminate and a cooled object, the surface contact between the panel 101 of the heat conducting device according to the illustrated specific embodiment of the present invention and the cooled object significantly improves the heat conduction efficiency. Meanwhile, compared with the welding process, the stamping method, e.g., cold forging, cold rolling, and cold breakdown, used in the production of the heat conducting device according to the specific embodiment of the present invention is easy to implement and facilitates quality control, and results in significantly lowered manufacturing cost. Moreover, use of the heat conducting device according to the present invention in a superconducting magnet of a magnetic resonance system improves the cooling performance. For example, cryogen loss rate is significantly reduced; and for a zero cryogen loss magnet, the low temperature redundancy, or recondensing margin, is improved.

FIG. 3A and FIG. 3B are schematic views illustrating connection between the heat conducting device 110 according to an embodiment of the present invention and a cold head 200 and a cooled object 301. As shown in FIG. 3A, a panel 101 of the heat conducting device according to an embodiment of the present invention is connected to a thermal coupling member 201 of a cold head 200 through bolts. Corresponding to FIG. 2A, the panel of the heat conducting device according to an embodiment of the present invention is provided with multiple bolt holes through which the heat conducting device 1 10 is thermally connected to the cold head 200 using the bolts to attach it to coupling member 201. As shown in FIG. 3B, the panel 101 of the heat conducting device 1 10 according to an embodiment of the present invention is connected to the thermal coupling member 201 of the cold head 200 by welding. Similarly, the panel 101 of the heat conducting device 100 according to the specific embodiment of the present invention may also be connected to a thermal shielding layer 301 of a superconducting magnet by bolts or by welding.

FIG. 4 is a schematic view of a cooling apparatus according to a specific embodiment of the present invention. As shown in FIG. 4, the cooling apparatus according to the specific embodiment of the present invention includes a cold head 200 and a heat conducting device 110. The heat conducting device 1 10 includes a rigid component 101 and a flexible component 102. As shown in Figs. 1A-2B, a recess is provided on one side of the rigid component 101 , one end of the flexible component 102 extends into the recess, and a wall of the recess part of the rigid component 101 and the flexible component 102 are stamped 100 from the outside, so as to connect the rigid component 101 and the flexible component 102. The other end of the flexible component 102 is connected to a thermal coupling member 201 of the cold head 200 also by stamping. In the illustrated embodiment, this stamping is performed in a direction perpendicular to a respective contact surface between the rigid component and a cooled object, although this is not necessarily the case.

According to an aspect of the present invention, the stamping method used for connection between the flexible component 102 and the rigid component 101 of the heat conducting device 100 and between the flexible component 102 and the thermal coupling member 201 of the cold head 200 is a non-welding process, that is, the flexible component is connected to the thermal coupling member through mechanical pressure completely, and the method that can be used includes cold rolling, cold breakdown, and cold forging. The material of the flexible component and the rigid component is a material of high heat conductivity, e.g., copper or aluminum. According to a specific embodiment of the present invention, the present invention further provides a magnetic resonance system, including a cooling apparatus and a superconducting magnet. The cooling apparatus according to the specific embodiment of the present invention includes a cold head 200 and a heat conducting device 100. The heat conducting device 110 includes a rigid component 101 and a flexible component 102. A recess is provided on one side of the rigid component 101, one end of the flexible component 102 extends into the recess, and a wall of the rigid component and the flexible component are stamped from the outside, so as to connect the rigid component 101 and the flexible component 102. The other end of the flexible component 102 is connected to a thermal coupling member 201 of the cold head 200 also by stamping. The rigid component of the heat conducting device 100 may be connected to a thermal shielding layer 301 of the superconducting magnet through bolts or by welding. The stamping is preferably carried out in a direction perpendicular to the intended contact surface between the rigid component and a cooled object. The stamping method used for connection between the flexible component 102 and the rigid component 101 of the heat conducting device 100 and between the flexible component 102 and the thermal coupling member 201 of the cold head 200 is a non- welding process, that is, the flexible component is connected to the thermal coupling member through mechanical pressure completely, and the method that can be used includes cold rolling, cold breakdown, and cold forging. The material of the flexible component and the rigid component is a material of high heat conductivity, e.g., copper or aluminum.

The present invention provides a heat conducting device, a cooling apparatus, and a magnetic resonance system. The heat conducting device includes a flexible component and a first rigid component, and one end of the flexible component is connected to the first rigid component by a stamping method. According to the technical solution of the present invention, the heat conducting device is manufactured by a stamping method, a simple process and excellent heat conductivity are achieved, and the cost can be saved with the same effect. The above descriptions are merely preferred embodiments of the present invention, but not intended to limit the present invention. Any modification, equivalent replacement, and improvement made without departing from the spirit and principle of the present invention shall fall within the scope of the present invention.