Low-temperature platform and refrigeration system

Abstract

The present invention discloses a cryogenic platform, which relates to the technical field of refrigeration applications. It mainly includes a cryogenic vibration damping platform body, a cold screen and a quasi-zero stiffness structure. The cryogenic vibration damping platform body is suspended inside the cold screen through an elastic member arranged inside the cold screen, and the top of the cryogenic vibration damping platform body can extend out of the cold screen. The quasi-zero stiffness structure is connected between the cryogenic vibration damping platform body and the cold screen. The cold screen is used to connect with the cold head of a refrigerator, and the cryogenic vibration damping platform body is used to couple with the device to be cooled. The present invention also discloses a refrigeration system, which includes the cryogenic platform as described above. The present invention can reduce the loss of refrigeration capacity, and has small deformation for large vibration forces, and has a good vibration damping effect.

Description

Technical Field

[0001] The present invention relates to the technical field of refrigeration applications, and particularly to a cryogenic platform and a refrigeration system. Background Art

[0002] In the field of modern cryogenic refrigeration, cryogenic refrigerators play an indispensable role. However, there is a relatively prominent problem with current cryogenic refrigerators: there are moving parts inside them, such as compressor pistons, expander rotors, etc. During the operation of the refrigerator, these moving parts will generate mechanical vibrations and transmit the vibration energy to the cryogenic platform, resulting in a large vibration output of the cryogenic platform.

[0003] Moreover, in actual use, various devices placed on the cryogenic platform, such as complex optical instruments, precision electronic components, etc., also have a certain degree of vibration themselves. The vibrations of these devices themselves are superimposed on the vibrations at the cold end of the cryogenic refrigerator and act together, ultimately resulting in an even larger vibration output of the cryogenic platform.

[0004] In the field of quantum computing, quantum bits are extremely fragile, and extremely small external vibration interferences may cause changes in the states of quantum bits, thereby seriously affecting the accuracy and stability of quantum computing. In the application scenario of electron microscopes, in order to obtain high-resolution microscopic images, it is required that the sample stage be at an extremely low vibration level. Because once there are large vibrations, the electron beam will deviate when scanning the sample, resulting in blurred imaging and unable to meet the requirements of high-precision observation of microscopic structures in scientific research and production.

[0005] Currently, there are some cryogenic platforms that can appropriately reduce vibrations. They use springs arranged under the cryogenic platform. The top of the spring is connected to the cryogenic platform, and the bottom is directly connected to the base of the refrigerator. The cold head of the refrigerator directly cools the cryogenic platform. Although this structure can reduce vibrations to a certain extent, the spring will also dissipate a part of the heat, so that the heat transferred from the cold head of the refrigerator to the cryogenic platform will be lost along the spring, affecting the refrigeration effect. Moreover, relying entirely on the spring to reduce vibrations, the cancellation ability is limited, and it is necessary to rely on the repeated small vibrations of the spring to gradually cancel the vibrations of the cryogenic platform. And the spring has a small tolerance for vibrations. As long as there is a small vibration source, the spring will vibrate accordingly. Therefore, there is an urgent need for a cryogenic platform and a refrigeration system to solve the above technical problems. Summary of the Invention

[0006] The purpose of the present invention is to provide a cryogenic platform and a refrigeration system to solve the problems existing in the above-mentioned prior art, which can reduce the loss of refrigeration capacity, and have a small deformation for large vibration forces, and have a good vibration reduction effect.

[0007] To achieve the above purpose, the present invention provides the following solutions:

[0008] The present invention provides a cryogenic platform, which includes a cryogenic vibration damping platform main body, a cold screen and a quasi-zero stiffness structure. The cryogenic vibration damping platform main body is suspended inside the cold screen through an elastic member disposed inside the cold screen, and the top of the cryogenic vibration damping platform main body can extend out of the cold screen. The quasi-zero stiffness structure is connected between the cryogenic vibration damping platform main body and the cold screen. The cold screen is used to connect to the cold head of a refrigerator, and the cryogenic vibration damping platform main body is used to couple with a device to be cooled.

[0009] In some embodiments, it further includes a heat conduction rod. The first end of the heat conduction rod is connected to the cryogenic vibration damping platform main body through a heat conduction structure, and the second end of the heat conduction rod is connected to the cold head in the low-temperature region of the refrigerator. And the heat conduction structure is a structure in which a positive stiffness heat conduction structure and a negative stiffness heat conduction structure are arranged in parallel. The stiffness of the positive stiffness heat conduction structure is K1, the stiffness of the negative stiffness heat conduction structure is K2, and K2 = -K1.

[0010] In some embodiments, the heat conduction rod is a cryogenic heat conduction rod.

[0011] In some embodiments, the cold screen includes a plurality of side plates connected end to end in sequence, a top plate and a bottom plate. The top plate covers above the plurality of side plates and its edge can be sealed. The bottom plate covers below the plurality of side plates and its edge can be sealed.

[0012] In some embodiments, the top plate has an opening. The top of the cryogenic vibration damping platform main body can pass through the opening, and there is a moving space between the top edge of the cryogenic platform and the edge of the opening.

[0013] In some embodiments, the top of the elastic member is fixedly connected to the top plate. A through hole is provided on the cryogenic vibration damping platform main body. The elastic member can pass through the through hole and be fixedly connected to the bottom of the through hole.

[0014] In some embodiments, the elastic member is a spring assembly. The total stiffness K3 of the spring assembly satisfies: , where m is the total mass of the cryogenic vibration damping platform main body.

[0015] In some embodiments, the spring assembly includes a plurality of springs, and the plurality of springs are arranged circumferentially along the cryogenic vibration damping platform main body.

[0016] In some embodiments, a plurality of the quasi-zero stiffness structures are arranged circumferentially along the cryogenic vibration damping platform main body.

[0017] The present invention also provides a refrigeration system, which includes the cryogenic platform as described above.

[0018] The present invention has achieved the following technical effects compared with the prior art:

[0019] The low-temperature platform provided by the present invention includes a low-temperature vibration damping platform main body and a cold screen. The low-temperature vibration damping platform main body is suspended inside the cold screen through an elastic member. The cold screen is used to connect to the cold head of a refrigerator. The cold screen forms a refrigeration barrier, which can effectively isolate heat. Connecting the cold screen to the cold head enables a certain low temperature inside the cold screen. The elastic member is also located inside the low-temperature cold screen and is in the same space as the low-temperature vibration damping platform main body. Whether the cold quantity inside the cold screen is directly transferred to the low-temperature vibration damping platform main body through the internal air or indirectly transferred to the low-temperature vibration damping platform main body through the elastic member, ultimately the low-temperature heat is transferred to the low-temperature platform without energy loss, and the refrigeration effect is better. Moreover, the use of the quasi-zero stiffness structure in combination with the elastic member for vibration damping can make full use of the characteristics of the high vibration damping efficiency of the quasi-zero stiffness structure and the good elastic energy storage and release characteristics of the elastic member, resulting in a better vibration damping effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0021] Figure 1 It is a schematic structural diagram of the low-temperature platform in some embodiments of the present invention;

[0022] Figure 2 It is a schematic structural diagram of the quasi-zero stiffness structure in some embodiments of the present invention;

[0023] Figure 3 It is a schematic diagram of the positive stiffness heat conduction structure in some embodiments of the present invention;

[0024] Figure 4 It is a schematic diagram of the negative stiffness heat conduction structure in some embodiments of the present invention.

[0025] In the figure: 1 - cold screen; 11 - top plate; 12 - side plate; 13 - bottom plate; 2 - low-temperature vibration damping platform main body; 3 - spring; 4 - positive stiffness heat conduction structure; 5 - low-temperature heat conduction rod; 6 - through hole; 7 - moving space; 8 - negative stiffness heat conduction structure; 9 - quasi-zero stiffness structure; 91 - bent plate. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0026] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0027] The object of the present invention is to provide a cryogenic platform and a refrigeration system to solve the problems existing in the prior art, which can reduce the loss of refrigerating capacity, and have small deformation for large vibration forces, and have good vibration damping effect.

[0028] To make the above objects, features and advantages of the present invention more obvious and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0029] Embodiment 1

[0030] As Figures 1 - 4 shown, the present invention provides a cryogenic platform, including a cryogenic vibration damping platform main body 2, a cold shield 1 and a quasi-zero stiffness structure 9. The cryogenic vibration damping platform main body 2 is suspended inside the cold shield 1 through an elastic member, and the top of the cryogenic vibration damping platform main body 2 can extend out of the cold shield 1. The quasi-zero stiffness structure 9 is connected between the cryogenic vibration damping platform main body 2 and the cold shield 1. Specifically, both ends of the quasi-zero stiffness structure 9 are fixedly connected to the outer wall of the cryogenic vibration damping platform main body 2 and the inner wall of the cold shield 1 respectively. The cold shield 1 is used to connect to the cold head of the high-temperature area of the refrigerator, and the cryogenic vibration damping platform main body 2 is used to couple with the device to be cooled. The cold shield 1 is equivalent to forming a refrigeration barrier, which can effectively isolate heat. Connecting the cold shield 1 to the cold head of the high-temperature area enables the inside of the cold shield 1 to have a certain low temperature. The elastic member is located inside the cryogenic cold shield 1 and is in the same space as the cryogenic vibration damping platform main body 2. Whether the cold quantity inside the cold shield 1 is directly transferred to the cryogenic vibration damping platform main body 2 through the internal air or indirectly transferred to the cryogenic vibration damping platform main body 2 through the elastic member, ultimately the low-temperature heat is transferred to the cryogenic platform without energy loss, and the refrigeration effect is good. Moreover, the elastic member can absorb vibration, making the operation of the cryogenic platform relatively stable. It should be noted that the cold shield can be a shell made of materials such as copper or aluminum, and then silver-plated or gold-plated.

[0031] Moreover, within its quasi-zero stiffness characteristic range, the quasi-zero stiffness structure 9 is extremely sensitive to vibration excitation and can absorb a large amount of vibration energy with a small displacement, thus effectively suppressing the propagation and amplification of vibration. Compared with traditional linear stiffness vibration damping structures, the quasi-zero stiffness structure 9 can achieve more significant vibration damping effects within a wider frequency range, greatly reducing the vibration amplitude and improving the stability of equipment and structures. The quasi-zero stiffness structure 9 is used in combination with elastic components for vibration damping, making full use of the high vibration damping efficiency of the quasi-zero stiffness structure 9 and the good elastic energy storage and release characteristics of the elastic components. The quasi-zero stiffness structure 9 can quickly absorb and dissipate a large amount of vibration energy during vibration, and the elastic components assist in buffering and regulating the energy, enabling the system to decay vibration more quickly. Compared with a single vibration damping element, it can more significantly reduce the vibration amplitude and improve the vibration damping effect. For low-frequency vibration, the vibration damping effect of the elastic components is relatively limited, while the quasi-zero stiffness structure 9 has good performance in the low-frequency band. After the two are combined, the quasi-zero stiffness structure 9 can make up for the deficiencies of the elastic components at low frequencies, enabling the entire system to work effectively under low-frequency vibration, better isolating the transmission of low-frequency vibration, and reducing the impact of low-frequency vibration on equipment and structures, which is particularly important for some equipment and structures sensitive to low-frequency vibration, such as precision instruments and electronic equipment.

[0032] As a feasible embodiment, as Figure 2 shown, the quasi-zero stiffness structure 9 can be set as a structure combining a bent plate 91 and a spring. By designing parameters such as the shape, size of the bent plate 91, and the stiffness and pre-tightening force of the spring, near a specific working point, the spring force caused by the deformation of the bent plate 91 cancels or balances the restoring force of the bent plate itself, thus achieving an approximately zero stiffness characteristic near this point. For example, the bent plate 91 is designed into a shape with non-linear stiffness characteristics, such as an S shape or the arc shape of this embodiment, and the stiffness of the spring is matched with the non-linear stiffness of the bent plate. Within a specific displacement range, the resultant force of the two changes very little with the displacement, showing a quasi-zero stiffness effect. During installation, the convex point of the bent plate 91 is fixed to the inner wall of the cold shield, and the edge point of the bent plate 91 and the spring are fixed to the outer side wall of the cryogenic vibration damping platform body 2.

[0033] In some embodiments, the low-temperature platform further includes a heat-conducting rod, the first end of which is connected to the low-temperature vibration reduction platform body 2 through a heat-conducting structure, and the second end of which is connected to the cold head in the low-temperature zone of the refrigerator. The presence of the heat-conducting rod provides an efficient channel for transferring the cold energy of the cold head in the low-temperature zone of the refrigerator to the low-temperature vibration reduction platform body 2. Since the heat-conducting rod is usually made of materials with high thermal conductivity, such as copper, aluminum, metal alloys, and metal-based composite materials, its thermal conductivity is much higher than that of air or elastic parts, etc., and it can quickly and in large quantities transfer the cold energy of the cold head in the low-temperature zone to the low-temperature vibration reduction platform body 2, greatly improving the cold energy transmission efficiency, so that the low-temperature vibration reduction platform body 2 can reach and maintain the required low temperature more quickly, thereby improving the refrigeration performance of the entire low-temperature platform.

[0034] As a preferred embodiment, the heat conduction structure is a structure in which a positive stiffness heat conduction structure 4 and a negative stiffness heat conduction structure 8 are arranged in parallel. The stiffness of the positive stiffness heat conduction structure 4 is K1, the stiffness of the negative stiffness heat conduction structure 8 is K2, and K2 = -K1. The specific parallel connection method is that the top of the positive stiffness heat conduction structure 4 and the top of the negative stiffness heat conduction structure 8 are both fixedly connected to the main body 2 of the low-temperature vibration damping platform, and the bottom of the positive stiffness heat conduction structure 4 and the bottom of the negative stiffness heat conduction structure 8 are both fixedly connected to the heat conduction rod. The parallel arrangement of the positive stiffness heat conduction structure 4 and the negative stiffness heat conduction structure 8 can effectively control the vibration of the structure. When the structure is vibrated by external excitation, the positive stiffness heat conduction structure 4 attempts to restore the initial state of the structure, while the negative stiffness heat conduction structure 8 can absorb and dissipate vibration energy through its special mechanical behavior. The combined action of the two can significantly reduce the vibration amplitude of the structure, improve the anti-vibration performance of the structure, broaden the vibration isolation frequency band, and have smaller vibrations within a larger force range. Moreover, in this embodiment, in addition to the vibration isolation effect of the elastic member and the quasi-zero stiffness structure 9, the heat conduction structure can also absorb and buffer vibrations to a certain extent. The combined vibration reduction of the elastic member, the quasi-zero stiffness structure 9, and the heat conduction mechanism can greatly reduce the vibration transmission from the cold head of the refrigerator and the environmental background to the main body 2 of the low-temperature vibration damping platform. During the operation of the equipment, the heat conduction rod will inevitably generate some vibrations, which may affect the connection stability and heat conduction effect between the heat conduction rod and the main body 2 of the low-temperature vibration damping platform. The vibration isolation characteristics of the heat conduction structure can reduce the influence of vibrations on the connection part to a certain extent, and further improve the operation stability of the low-temperature platform. It should be noted that the heat conduction structure also needs to have a high heat transfer rate, such as oxygen-free copper, silicone rubber material filled with graphene, etc. And the heat conduction rod is preferably a low-temperature heat conduction rod 5, which refers to a heat conduction rod that can transfer cold better and can operate well in a low-temperature environment. The low-temperature heat conduction rod 5 has excellent heat conduction performance in a low-temperature environment and can more effectively transfer the cold of the cold head in the low-temperature area of the refrigerator to the main body 2 of the low-temperature vibration damping platform. Compared with the situation where the heat conduction performance of an ordinary heat conduction rod may decline at low temperatures, the low-temperature heat conduction rod 5 can ensure the rapid and stable transmission of cold, enable the main body 2 of the low-temperature vibration damping platform to reach and maintain the required low-temperature state faster, and improve the refrigeration efficiency and refrigeration effect. It should be noted that the low-temperature heat conduction rod 5 can be a heat conduction rod made of copper, aluminum, alloy material or carbon fiber composite material.

[0035] In some embodiments, the cold shield 1 includes a plurality of side panels 12 connected end to end in sequence to form an annular chamber or a square chamber or other shaped chambers, a top panel 11 and a bottom panel 13. The top panel 11 covers the upper end of the chamber and its edges can form a sealed connection. The bottom panel 13 covers the lower end of the chamber and its edges can form a sealed connection. By sealingly connecting a plurality of side panels 12, the top panel 11 and the bottom panel 13 to form a relatively closed space, the influence of heat conduction and heat convection can be reduced to a certain extent, which helps to maintain the low temperature state inside the cold shield 1, improve the refrigeration efficiency and stability of the low temperature platform, and reduce the energy consumption of the refrigerator.

[0036] In some embodiments, the top plate 11 has an opening, and the top of the low-temperature vibration reduction platform body 2 can pass through the opening, and there is a circular or square moving space 7 between the low-temperature platform and the opening. The specific shape can be determined according to the shape of the low-temperature vibration reduction platform body 2. The setting of the moving space 7 allows the low-temperature vibration reduction platform body 2 to have a certain deflection. For example, for vibration in the inclined direction, on the one hand, the elastic part will move up and down, and on the other hand, the elastic part will move left and right. When the elastic part moves left and right, the low-temperature vibration reduction platform body 2 will also have a certain degree of left and right movement. The moving space 7 ensures the possibility of left and right movement.

[0037] As a preferred embodiment, the low-temperature vibration reduction platform body 2 is stepped, the small end can extend from the opening, and the width of the large end is greater than the width of the opening, limiting the maximum extension distance of the low-temperature platform. On the one hand, it can protect the elastic parts from excessive compression, and on the other hand, it can prevent the low-temperature vibration reduction platform body 2 from flying out of the cold screen 1.

[0038] In some embodiments, the top of the elastic member is fixedly connected to the top plate 11, and a through hole 6 is provided on the low-temperature vibration reduction platform body 2. Specifically, the through hole 6 is provided at the large end, and the elastic member can pass through the through hole 6 and is fixedly connected to the bottom of the through hole 6. The upper and lower ends of the elastic member are respectively fixedly connected to the top plate 11 and the low-temperature vibration reduction platform body 2 to form a stable suspension structure, which can effectively isolate the transmission of external vibration to the low-temperature vibration reduction platform body 2 and provide a stable working environment for the objects carried on the platform. The through hole 6 has a certain limiting and guiding effect on the position of the elastic member, ensuring that the movement of the low-temperature vibration reduction platform body 2 in the vertical direction is relatively stable, avoiding excessive shaking or displacement of the platform body under the action of the elastic member, and only allowing a small degree of displacement.

[0039] In some embodiments, the elastic member is a spring assembly, and the total stiffness K3 of the spring assembly satisfies: , where m is the total mass of the main body of the low-temperature vibration damping platform. And a plurality of springs 3 are provided and arranged along the circumferential direction of the main body 2 of the low-temperature vibration damping platform. The circumferential arrangement of the plurality of springs 3 can make the supporting force and buffering force received by the main body 2 of the low-temperature vibration damping platform more uniform in all directions. It can avoid the stress concentration phenomenon caused by single-point or local support, and make the platform main body more stable when bearing the load.

[0040] It should be noted that the spring 3 can also be set to one, and the setting method of one spring 3 is to be sleeved on the outside of the main body 2 of the low-temperature vibration damping platform.

[0041] As a preferred embodiment, a plurality of quasi-zero stiffness structures 9 are arranged along the circumferential direction of the main body 2 of the low-temperature vibration damping platform and are connected to the outer side surface of the main body 2 of the low-temperature vibration damping platform. The plurality of circumferentially arranged quasi-zero stiffness structures 9 can isolate vibration from multiple directions on the side surface of the main body 2 of the low-temperature vibration damping platform, ensuring the vibration isolation effect.

[0042] Embodiment 2

[0043] This embodiment also provides a refrigeration system, including the low-temperature platform described in Embodiment 1, which can reduce the loss of refrigeration capacity, and has a small deformation for large vibration forces, and has a good vibration damping effect.

[0044] In the present invention, specific examples are used to elaborate on the principle and implementation manner of the present invention. The description of the above embodiments is only used to help understand the method and its core idea of the present invention; at the same time, for those of ordinary skill in the art, according to the idea of the present invention, there will be changes in the specific implementation manner and application scope. In summary, the content of this specification should not be construed as a limitation to the present invention.

Claims

1. A low-temperature platform, characterized in that: It includes a cryogenic vibration damping platform body, a cold shield, a heat conduction rod and a quasi-zero stiffness structure. The cryogenic vibration damping platform body is suspended inside the cold shield through an elastic member arranged inside the cold shield, and the top of the cryogenic vibration damping platform body can extend out of the cold shield. The quasi-zero stiffness structure is connected between the cryogenic vibration damping platform body and the cold shield. The cold shield is used to connect with the cold head of a refrigerator, the cryogenic vibration damping platform body is used to be coupled with a device to be cooled. The first end of the heat conduction rod is connected with the cryogenic vibration damping platform body through a heat conduction structure, the second end of the heat conduction rod is connected with the cold head in the low-temperature area of the refrigerator, and the heat conduction structure is a parallel arrangement structure of a positive stiffness heat conduction structure and a negative stiffness heat conduction structure. The stiffness of the positive stiffness heat conduction structure is K1, the stiffness of the negative stiffness heat conduction structure is K2, and K2 = -K1.

2. The cryogenic platform according to claim 1, wherein: The heat conduction rod is a cryogenic heat conduction rod.

3. The cryogenic platform according to claim 1, characterized in that: The cold shield includes a plurality of side plates connected end to end in sequence, a top plate and a bottom plate. The top plate covers above the plurality of side plates and its edge can be sealed. The bottom plate covers below the plurality of side plates and its edge can be sealed.

4. The cryogenic platform according to claim 3, wherein: There is an opening on the top plate. The top of the cryogenic vibration damping platform body can pass through the opening, and there is a moving space between the edge of the top of the cryogenic platform and the edge of the opening.

5. The cryogenic platform according to claim 4, wherein: The top of the elastic member is fixedly connected with the top plate. A through hole is arranged on the cryogenic vibration damping platform body. The elastic member can pass through the through hole and is fixedly connected with the bottom of the through hole.

6. The cryogenic platform according to claim 1, wherein: The elastic member is a spring assembly, and the total stiffness K3 of the spring assembly satisfies: , where m is the total mass of the main body of the cryogenic vibration damping platform.

7. The cryogenic platform according to claim 6, characterized in that: The spring assembly includes a plurality of springs, and the plurality of springs are arranged along the circumferential direction of the cryogenic vibration damping platform body.

8. The cryogenic platform according to claim 1, characterized in that: A plurality of the quasi-zero stiffness structures are arranged along the circumferential direction of the cryogenic vibration damping platform body.

9. A refrigeration system, characterized in that: It includes the cryogenic platform according to any one of claims 1-8.

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