阅读说明：本技术 一种带有主动式振动衰减结构的无液氦低温制冷系统 (Liquid helium-free low-temperature refrigeration system with active vibration attenuation structure ) 是由 吴施伟 孙泽元 陈旭涛 殷立峰 高春雷 沈健 于 2021-05-17 设计创作，主要内容包括：本发明属于低温制冷设备技术领域,具体为一种带有主动式振动衰减结构的无液氦低温制冷系统。本发明制冷系统包括闭循环制冷机、主动式振动衰减系统、低温运行设备、低温屏蔽罩和真空腔体；主动式振动衰减系统包括固定支架、振动传感器、主动式振动衰减器和振动衰减系统控制器;主动式振动衰减器、振动传感器均与振动衰减系统控制器电连接；闭循环制冷机的制冷头伸入制冷隔振界面内,制冷头和制冷隔振界面间填充氦气,闭循环制冷机与制冷隔振界面的之间通过密封波纹管连接密封；低温运行设备放置在真空腔体内并与制冷隔振界面的低温端连接。本发明有效降低振动对低温设备运行的影响,大大提高低温设备的运行精度,且成本低,占地面积小。(The invention belongs to the technical field of low-temperature refrigeration equipment, and particularly relates to a liquid helium-free low-temperature refrigeration system with an active vibration attenuation structure. The refrigerating system comprises a closed-cycle refrigerator, an active vibration attenuation system, low-temperature operation equipment, a low-temperature shielding cover and a vacuum cavity; the active vibration attenuation system comprises a fixed support, a vibration sensor, an active vibration attenuator and a vibration attenuation system controller, wherein the active vibration attenuator and the vibration sensor are electrically connected with the vibration attenuation system controller; a refrigerating head of the closed-cycle refrigerator extends into the refrigerating vibration isolation interface, helium is filled between the refrigerating head and the refrigerating vibration isolation interface, and the closed-cycle refrigerator and the refrigerating vibration isolation interface are connected and sealed through a sealing corrugated pipe; the low-temperature operation equipment is placed in the vacuum cavity and is connected with the low-temperature end of the refrigeration vibration isolation interface. The invention effectively reduces the influence of vibration on the operation of the low-temperature equipment, greatly improves the operation precision of the low-temperature equipment, and has low cost and small occupied area.)

1. A liquid helium-free low-temperature refrigerating system with an active vibration attenuation structure is characterized by comprising a closed-cycle refrigerator, an active vibration attenuation system, low-temperature operation equipment, a low-temperature shielding cover and a vacuum cavity; wherein:

in the closed-cycle refrigerator, a refrigerating head of the closed-cycle refrigerator extends into a refrigerating vibration isolation interface, helium is filled between the refrigerating head and the refrigerating vibration isolation interface, and the closed-cycle refrigerator and the refrigerating vibration isolation interface are connected and sealed through a sealing corrugated pipe;

the active vibration attenuation system comprises a fixed support, a vibration sensor, an active vibration attenuator and an active vibration attenuation system controller; the base of the closed-cycle refrigerator is connected with the fixed support, the active vibration attenuator is installed between the base of the closed-cycle refrigerator and the fixed support, the vibration sensor is installed on the base of the closed-cycle refrigerator, and the active vibration attenuator and the vibration sensor are both electrically connected with the active vibration attenuation system controller;

the low-temperature operation equipment is placed in a vacuum cavity and is connected with the low-temperature end of the refrigeration vibration isolation interface, the vacuum cavity is placed on the ground supporting unit, and the low-temperature shielding cover is arranged between the low-temperature operation equipment and the vacuum cavity;

the cold vibration isolation interface is formed by enclosing a low-temperature shielding cover, a sealing corrugated pipe and a closed-cycle refrigerator.

2. The refrigeration system according to claim 1, wherein the vibration sensor is provided in plurality for measuring acceleration, angular velocity, and linear velocity, and the plurality of vibration sensors are uniformly distributed on a base of the closed-cycle refrigerator.

3. The refrigerant system as set forth in claim 1, wherein the bottom of said stationary bracket rests directly on the ground.

4. The refrigerant system as set forth in claim 1, wherein said active vibration attenuation system controller is placed separately in an equipment cabinet or integrated in said active vibration attenuator, vibration sensor.

5. The refrigeration system of claim 1 wherein said cryo-shield is coupled to said refrigeration vibration isolation interface, and wherein refrigeration generated by said closed cycle refrigerator is conducted to said cryo-shield through said refrigeration vibration isolation interface.

6. The refrigeration system of claim 1 wherein the vacuum chamber is secured to the floor support unit by a rigid connection.

7. The refrigeration system of claim 6 wherein the floor support unit is a rubber pad or air spring isolating floor vibrations, or a rigid bracket.

Technical Field

The invention belongs to the technical field of low-temperature refrigeration equipment, and particularly relates to a liquid helium-free low-temperature refrigeration system with an active vibration attenuation structure.

Background

At present, closed-cycle refrigerators, such as gifford-mcmahon refrigerators, pulse tube refrigerators and other low-temperature refrigeration systems, emerge in the field of low-temperature refrigeration equipment, and obtain low temperature without liquid helium consumption, but the operation of the closed-cycle refrigerator introduces non-negligible low-frequency mechanical vibration, which limits the application of the closed-cycle refrigerator in the requirements of low vibration and low-temperature environment. Since cryogenically operated equipment is very sensitive to mechanical vibrations, the presence of such mechanical vibrations will affect the acquisition of normal signals, such as scanning probe microscopy.

In order to solve the mechanical vibration during the operation of the closed-cycle refrigerator, those skilled in the art have developed some cryogenic refrigeration systems without liquid helium consumption based on mechanical vibration isolation structures, such as the patent with application number 201610002349.8 entitled no liquid helium consumption cryogenic refrigeration system with mechanical vibration isolation. The main principle is that the closed-cycle refrigerator is connected with a fixed support, low-temperature heat exchange is realized between the refrigerator and low-temperature operation equipment through helium, and helium gas is sealed by using a sealing corrugated pipe between the refrigerator and the low-temperature operation equipment.

Therefore, it is an urgent technical problem to be solved by those skilled in the art to develop a refrigeration technology capable of achieving a low temperature and a low vibration environment without consuming liquid helium.

Disclosure of Invention

The invention aims to provide a liquid helium-free low-temperature refrigerating system with an active vibration attenuation structure, which directly attenuates vibration energy generated during the operation of a refrigerator through the active vibration attenuation structure and reduces the noise problem of the vibration of the refrigerator on low-temperature operation equipment.

The invention provides a liquid helium-free low-temperature refrigeration system with an active vibration attenuation structure, which comprises a closed-cycle refrigerator, an active vibration attenuation system, low-temperature running equipment, a low-temperature shielding cover and a vacuum cavity, wherein the closed-cycle refrigerator is used for storing a refrigerating medium; wherein:

in the closed-cycle refrigerator, a refrigerating head of the closed-cycle refrigerator extends into a refrigerating vibration isolation interface, helium is filled between the refrigerating head and the refrigerating vibration isolation interface, and the closed-cycle refrigerator and the refrigerating vibration isolation interface are connected and sealed through a sealing corrugated pipe;

the active vibration attenuation system comprises a fixed support, a vibration sensor, an active vibration attenuator and an active vibration attenuation system controller, wherein a base of the closed cycle refrigerator is connected with the fixed support, the active vibration attenuator is installed between the base of the closed cycle refrigerator and the fixed support, the vibration sensor is installed on the closed cycle refrigerator, and the active vibration attenuator and the vibration sensor are both electrically connected with the active vibration attenuation system controller;

the low-temperature operation equipment is placed in a vacuum cavity and is connected with the low-temperature end of the refrigeration vibration isolation interface, the vacuum cavity is placed on the ground supporting unit, and a low-temperature shielding cover is arranged between the low-temperature operation equipment and the vacuum cavity;

the cold vibration isolation interface is formed by enclosing a low-temperature shielding cover, a sealing corrugated pipe and a closed-cycle refrigerator.

Furthermore, the vibration sensors are arranged in a plurality and are respectively used for measuring acceleration, angular velocity and linear velocity, and the vibration sensors are uniformly distributed on the base of the closed-cycle refrigerator.

Further, the bottom of the fixed bracket is directly placed on the ground,

further, the active vibration attenuation system controller is independently arranged in an equipment cabinet or integrated in the active vibration attenuator and the vibration sensor.

Furthermore, the low-temperature shielding cover is connected with the refrigeration vibration isolation interface, and refrigeration quantity generated by the closed-cycle refrigerator is transmitted to the low-temperature shielding cover through the refrigeration vibration isolation interface.

Further, the vacuum chamber is fixed on the ground support unit through rigid connection.

Furthermore, the ground support unit adopts a rubber pad or an air spring for isolating ground vibration.

Further, the ground support unit adopts a rigid support.

Compared with the prior art, the invention has the beneficial technical effects that:

the invention comprises a closed-cycle refrigerator, an active vibration attenuation system and low-temperature operation equipment, wherein the refrigeration mode provided on the basis can realize a low-temperature working environment for the low-temperature operation equipment under the condition of not consuming a refrigerant (such as expensive liquid helium), and meanwhile, the active vibration attenuation system can monitor the vibration state of the closed-cycle refrigerator in real time when the refrigerator works and feed back the attenuation force to the refrigerator through an active vibration attenuator, so that the energy of the mechanical vibration of the closed-cycle refrigerator is reduced, a ground support unit is added, and the mechanical vibration noise at the low-temperature operation equipment end is greatly reduced.

The active vibration attenuator used in the invention only needs to attenuate the vibration energy of the closed-cycle refrigerator, and the weight of the conventional closed-cycle refrigerator is not more than 40 kg, so that the attenuation of the vibration energy can be realized only by a very small active vibration attenuator, a ton-level large vibration isolation platform used for reducing vibration noise in a mechanical vibration isolation liquid-free helium system is avoided, and the cost of vibration isolation equipment and the cost of device construction are greatly reduced.

The active vibration attenuation structure used in the invention attenuates the vibration energy of the closed-cycle refrigerator from the source, the fixed end of the closed-cycle refrigerator does not need to depend on a heavy and high-strength fixed support, and the fixed support does not need to perform open structure transformation on the installed fixed end, so that the use threshold of the liquid-helium-free vibration isolation refrigerating device is greatly reduced, and the installation, transportation and transformation cost of the working environment are reduced.

The invention effectively reduces the influence of vibration on the operation of the low-temperature equipment, greatly improves the operation precision of the low-temperature equipment, and has low cost and small occupied area.

Drawings

FIG. 1 is a schematic representation of the configuration of the present invention for a liquid helium free cryogenic refrigeration system with active vibration attenuation.

Reference numerals: 1 is a closed-cycle refrigerator; 2 is a refrigeration vibration isolation interface; 3 is a sealing corrugated pipe; 4, low-temperature operation equipment; 5 is a fixed bracket; 6 is a vibration sensor; 7 is an active vibration attenuator; 8 is an active vibration damping system controller; 9 is a vacuum cavity; 10 is a low-temperature shielding case; and 11 is a ground support unit.

Detailed Description

The invention is further illustrated by the following examples and figures.

As shown in fig. 1, a liquid helium-free cryogenic refrigeration system with an active vibration attenuation structure includes a closed-cycle refrigerator 1, an active vibration attenuation system, and a cryogenic operating device 4; a refrigerating head of the closed-cycle refrigerator 1 extends into the refrigerating vibration isolation interface 2, the closed-cycle refrigerator 1 is not in contact with the refrigerating vibration isolation interface 2, and helium is filled between the refrigerating head and the refrigerating vibration isolation interface 2 to serve as a refrigerating and cooling medium; the closed-cycle refrigerator 1 and the refrigeration vibration isolation interface 2 are connected and sealed through the sealing corrugated pipe 3, the mechanical vibration transmitted to the refrigeration vibration isolation interface 2 by the closed-cycle refrigerator 1 can be reduced to a certain extent while helium is sealed, and part of energy of vibration of the closed-cycle refrigerator 1 is transmitted to the refrigeration vibration isolation interface 2 below through the sealing corrugated pipe 3 according to different materials and structures of the sealing corrugated pipe 3; the active vibration attenuation system comprises a fixed support 5, an active vibration attenuation system controller 8, an active vibration attenuator 7 and a vibration sensor 6, wherein the base of the closed-cycle refrigerator 1 is connected with the fixed support 5, the active vibration attenuator 7 is arranged between the base of the closed-cycle refrigerator 1 and the fixed support 5, the vibration sensor 6 is arranged on the closed-cycle refrigerator 1, and the active vibration attenuator 7 and the vibration sensor 6 are both electrically connected with the active vibration attenuation system controller 8; the low-temperature operation equipment 4 is placed in the vacuum cavity 9 and connected with the low-temperature end of the refrigeration vibration isolation interface 2, the vacuum cavity 9 is placed on the ground supporting unit 11, the low-temperature shielding cover 10 is arranged between the low-temperature operation equipment 4 and the vacuum cavity 9, and heat load brought by heat radiation is reduced through the low-temperature shielding cover 10.

The vacuum cavity 9 and the low-temperature shielding case 10 are designed to be provided with upper openings, the upper end of the vacuum cavity 9 is hermetically connected with the closed-cycle refrigerator 1 through the sealing corrugated pipe 3 made of flexible materials, the lower end of the closed-cycle refrigerator 1 is arranged in the low-temperature shielding case 10 in a penetrating manner, and the low-temperature shielding case 10, the sealing corrugated pipe 3 and the closed-cycle refrigerator 1 are arranged in a surrounding manner to form a refrigeration vibration isolation interface 2.

In the embodiment, the refrigerating system realizes refrigeration through the closed-cycle refrigerator 1, the refrigerating head conducts refrigerating capacity to the refrigerating vibration isolation interface 2 through helium, and then the refrigerating capacity is conducted to equipment 4 needing to be operated at low temperature through the refrigerating vibration isolation interface 2; the signal of the vibration sensor 6 is input to the active vibration isolation and attenuation system controller 8, and after signal processing in the active vibration isolation and attenuation system controller 8, the active vibration attenuator 7 is controlled to generate an attenuation force, so that the vibration energy of the closed cycle refrigerator 1 is cancelled or partially cancelled.

The type of the closed-cycle refrigerator 1 includes, but is not limited to, gifford-mcmahon refrigerators, stirling refrigerators, pulse tube refrigerators, and modified refrigerators based on these principles, and any device that can provide a certain low-temperature refrigeration capacity and mechanical vibration with a specific frequency at the cold head, which can be considered by those skilled in the art; the working principle of the active vibration damper 7 includes, but is not limited to, an air floating type damper, a piezoelectric ceramic type damper, an electromagnetic coil type damper, a linear motor type damper, etc.; the signal processing principles of the active vibration damping system controller 8 include, but are not limited to, PID feedback, fourier spectrum feedback, and machine learning based signal processing techniques.

Specifically, a plurality of vibration sensors 6 for measuring acceleration, angular velocity, and linear velocity are provided, and the plurality of vibration sensors 6 are uniformly distributed on the base of the closed-cycle refrigerator 1.

The vibration sensor 6 of the present embodiment can measure the mechanical vibration of the closed-cycle refrigerator 1 during operation in real time, including signals of acceleration, velocity, displacement and time in three dimensions. The signal of the vibration sensor 6 is input to the active vibration damping system controller 8, and after signal processing in the active vibration damping system controller 8, the active vibration damper 7 is controlled to generate a damping force, thereby canceling or partially canceling the vibration energy of the closed cycle refrigerator 1. The vibration sensor 6 may be installed in plural to realize the measurement of the angular acceleration, the angular velocity, and the linear velocity of the closed-cycle refrigerator 1.

Specifically, the bottom of the fixed support 5 is directly placed on the ground, and the active vibration attenuation system controller 8 is placed on one side of the fixed support 5 through the support, or the active vibration attenuation system controller 8 is independently placed in the equipment cabinet, or the active vibration attenuation system controller 8 is integrated in the active vibration attenuator 7 and the vibration sensor 6.

The fixing support 5 of the present embodiment can also be placed on a wall or ceiling, as well as in a position having a certain mechanical strength and structural stability as will occur to those skilled in the art.

Specifically, the ground support unit 11 employs a rubber pad or an air spring for isolating ground vibration. The ground support unit 11 is a rigid support.

In the present embodiment, when the ground vibration is small, the ground support unit 11 is a rigid bracket, and when the ground vibration is large, the ground support unit 11 is a device capable of isolating the ground vibration, such as a rubber pad or an air spring.

The working process of the invention is as follows:

firstly, the refrigeration system realizes refrigeration through the closed-cycle refrigerator 1, taking the closed-cycle refrigerator 1 as example of Japanese Sumitomo SRDK-415D, the no-load temperature and the refrigeration power of a first-stage cold head and a second-stage cold head of the closed-cycle refrigerator 1 can reach 50K @35W and 4.2K @ 1.5W. The refrigerating head of the closed-cycle refrigerator 1 transmits refrigerating capacity to the refrigerating vibration isolation interface 2 through helium, and then the refrigerating capacity is transmitted to equipment 4 needing to operate at low temperature through the refrigerating vibration isolation interface 2; the closed-cycle refrigerator 1 and the low-temperature operation equipment 4 realize low-temperature heat exchange through helium, the closed-cycle refrigerator 1 and the low-temperature operation equipment 4 are sealed by using the sealing corrugated pipe 3, helium is not consumed, and the closed-cycle refrigerator 1 is not in contact with the refrigeration vibration isolation interface 2, so that mechanical vibration generated when the closed-cycle refrigerator 1 works is not directly transmitted to the low-temperature operation equipment 4.

Secondly, the closed-cycle refrigerator 1 is fixedly connected with the active vibration damper 7, the active vibration damper 7 is fixedly connected with the fixed support 5, and the fixed support 5 is placed on the ground. The vibration sensor 6 and the closed-cycle refrigerator 1 are fixedly installed and can measure the vibration state of the refrigerator in real time, the active vibration attenuator 7 and the vibration sensor 6 are connected to the active vibration attenuation system controller 8 through cables, and after the active vibration attenuation system controller 8 receives and processes signals from the vibration sensor 6, the active vibration attenuator 7 is controlled to generate an attenuation force to counteract or partially counteract the vibration energy of the closed-cycle refrigerator 1.

The signal processing of the active vibration attenuation system controller 8 may be based on PID control, and the vibration signal of each dimension is fed back in real time according to a certain P, I, D parameter, and the active vibration attenuator 7 is controlled to generate a corresponding attenuation force. After the closed-cycle refrigerator 1 and the fixed support 5 are installed, the vibration frequency and the vibration energy at each frequency in the normal operation state are basically fixed, so a machine learning algorithm can be adopted, the signal obtained by the vibration sensor 6 is subjected to real-time Fourier transform to obtain frequency spectrum data in the vibration state, the frequency, the amplitude and the phase of a characteristic frequency peak in the frequency spectrum are used as feedback force variables for machine learning, and the optimal variable value is obtained through long-time work. Taking a conventional gifford-mcmahon refrigerator as an example, the operating frequency of the refrigerator is usually 2 Hz, the active vibration attenuator 7 can attenuate the vibration acceleration of the refrigerator in X, Y, Z three directions by an order of magnitude, and can further attenuate the vibration of a specific frequency, for example, by algorithm optimization of the control system.

Finally, the low-temperature operation equipment 4 is connected to the low-temperature end of the refrigeration vibration isolation interface 2 and is placed inside the vacuum cavity 9. A low-temperature shielding cover 10 is arranged between the low-temperature operation equipment 4 and the vacuum cavity 9 to isolate heat radiation between low temperature and room temperature, and the low-temperature cold shielding cover 10 conducts refrigerating capacity of the closed-cycle helium refrigerator 1 to the low-temperature cold shielding cover 10 through connection with the refrigerating vibration isolation interface 2. The vacuum chamber 9 is placed on the ground support unit 11, the ground support unit 11 is placed on the ground, and the vibration of the ground is isolated by the ground support unit 11.

The above-described embodiments are merely illustrative of the preferred embodiments of the present invention, and do not limit the scope of the present invention, and various modifications and improvements of the technical solution of the present invention can be made by those skilled in the art without departing from the spirit of the present invention, and the scope of the present invention is defined by the claims.