An expander assembly and stirling refrigerator

Abstract

The application relates to an expander assembly and a Stirling refrigerator, which comprises an expander base, a cold finger in sealed connection with the expander base, a pusher assembly in the expander base and the cold finger, and an expansion cavity formed by the cold finger and the pusher assembly; and a magnetic spring assembly arranged close to the expansion cavity and used for generating a magnetic force applied to the pusher assembly, wherein the action direction of the magnetic force is opposite to the movement direction of the pusher assembly during movement. The magnetic part of the application is continuously in a low-temperature environment, so as to continuously have a larger magnetic flux, and the magnetic part is prevented from falling off due to debonding, and meanwhile, the overall volume of the product is further reduced, so that the product structure is more compact.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of Stirling cryocooler, and particularly relates to an expander assembly and a Stirling cryocooler. BACKGROUND

[0002] The existing Stirling cryocooler usually compresses gas working medium by a compressor, and then generates pneumatic force to drive the guide piston of the expander to move, and further drives the displacement assembly to reciprocate in the cold finger to achieve the refrigeration effect.

[0003] Among them, as shown in the technical solution of the Stirling cryocooler expander and the Stirling cryocooler with the application number 202322895752.6 and the patent name, a plate spring, a column spring and the like are usually connected with the piston, and the stiffness of the system is controlled by adjusting the spring. However, the use of mechanical spring will increase the axial or radial size of the expander, which cannot realize the miniaturization of the expander, and in addition, due to the reciprocating motion of the displacement assembly, the mechanical spring has the risk of fatigue fracture, which leads to the failure of the cryocooler. SUMMARY

[0004] The purpose of the present application is to provide an expander assembly and a Stirling cryocooler, which continuously has greater magnetic flux in the low-temperature environment, avoids the magnetic part from falling off due to debonding, and further reduces the overall volume of the product, making the product structure more compact.

[0005] To achieve the above purpose, the present application provides the following technical solutions:

[0006] On the one hand, an expander assembly of a Stirling cryocooler is provided, which comprises an expander base, a cold finger in sealing connection with the expander base, and a displacement assembly located in the expander base and the cold finger, and an expansion cavity is formed by the cold finger and the displacement assembly; and a magnetic spring assembly is arranged close to the expansion cavity, used to generate a magnetic force acting on the displacement assembly, and the direction of the magnetic force is opposite to the direction of the movement of the displacement assembly.

[0007] Preferably, the magnetic spring assembly comprises:

[0008] An internal magnetic part is arranged inside one end of the cold accumulator shell of the displacement assembly close to the expansion cavity, and is connected with the inner wall of the cold accumulator shell;

[0009] An external magnetic part is arranged outside the cold cylinder of the cold finger, and is connected with the outer wall of the cold cylinder at a position corresponding to the expansion cavity;

[0010] The internal magnetic part and the external magnetic part are magnetized in the radial direction, and the magnetization directions are the same.

[0011] Preferably, the internal magnetic member and the external magnetic member are permanent magnets.

[0012] Preferably, the internal magnetic member is in a ring-shaped integral structure or in a ring-shaped split structure formed by splicing a plurality of component units, and / or the external magnetic member is in a ring-shaped integral structure or in a ring-shaped split structure formed by splicing a plurality of component units.

[0013] Preferably, the magnetic force spring assembly further comprises an internal magnetic member limiting member connected to the cold accumulator shell for limiting the axial position of the internal magnetic member.

[0014] Preferably, the magnetic force spring assembly further comprises an external magnetic member limiting member connected to the outer wall surface of the cold finger cylinder for limiting the axial position and / or radial position of the external magnetic member.

[0015] Preferably, the external magnetic member limiting member comprises a radial limiting portion located at the periphery of the external magnetic member as a whole, and one end of which is connected to the lower surface of the cold plate for closing the opening of the end of the cold finger cylinder, and / or an axial limiting portion located below the external magnetic member as a whole, and one end of which is connected to the outer wall surface of the cold finger cylinder.

[0016] Preferably, the free end of the radial limiting portion and the free end of the axial limiting portion are connected to form a structure with a longitudinal section in the shape of "L".

[0017] Preferably, the expander assembly further comprises a cylinder fitting sealing member for sealing the fitting part of the guide cylinder of the pusher assembly and the cold finger.

[0018] Preferably, the expander assembly further comprises a cold finger fitting sealing member for sealing the fitting part of the cold finger and the expander base.

[0019] In another aspect, a Stirling refrigerator is also provided, which comprises the above expander assembly.

[0020] In summary, the present application has the following beneficial effects compared with the prior art:

[0021] The magnetic member in the present application is continuously in a low-temperature environment, so it continuously has a larger magnetic flux. Therefore, the situation that the magnetic force spring stiffness becomes smaller due to the attenuation of the magnetic flux of the magnetic member in a high-temperature environment can be avoided. At the same time, it is helpful to further reduce the overall volume of the product, so that the product structure is more compact. In addition, since the magnetic member is in a low-temperature environment, the adhesive used for bonding can maintain the bonding performance for a long time, avoiding the magnetic member from falling off due to debonding. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 FIG. 4 is a sectional view of the expander assembly in the present application.

[0023] Figure 2 This is a schematic diagram showing the magnetization direction of the internal and external magnetic components in this invention. Detailed Implementation

[0024] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0025] Example 1

[0026] like Figure 1 As shown, this embodiment provides an expander assembly for a Stirling refrigerator, which includes:

[0027] Expander base 12;

[0028] The cold finger 3 is sealed to the expander base 12 and has a cold finger cylinder 31. In this embodiment, the opening of the cold finger cylinder 31 away from the expander base 12 is closed by the cold plate 1. For example, the cold plate 1 can be connected to the end of the cold finger cylinder 31 by welding, bonding or other means to close the end opening. At the same time, the cold finger cylinder 31 is a cylindrical structure made of titanium alloy material and the wall thickness is less than 0.2mm, thereby reducing weight while ensuring structural strength. Meanwhile, the structure after the expander base 12 and the cold finger 3 are sealed together has an internal cavity 100, and the internal cavity 100 includes a back pressure cavity 101 near the expander base 12 and a room temperature cavity 102 near the cold finger cylinder 31. The back pressure cavity 101 and the room temperature cavity 102 are interconnected.

[0029] The cold accumulator has a cold accumulator shell 15 and an energy storage material 6 (such as wire mesh) filled inside the cold accumulator shell 15. One end of the cold accumulator shell 15 extends into the interior of the cold finger cylinder 31 and forms an expansion cavity 33 with the inner wall surface of the end of the cold finger cylinder 31 away from the expander base 12 and the cold plate 1. The cold accumulator shell 15 and the cold finger cylinder 31 are in clearance fit.

[0030] A guide cylinder 7 is disposed inside the internal cavity 100 and is connected to the inner wall surface of the cold finger 3 and / or the inner wall surface of the expander base 12 by means of bonding or other methods; furthermore, the cold finger 3 is also provided with an air inlet 32 ​​that communicates with the interior of the guide cylinder 7.

[0031] A guide piston 8 is arranged inside the guide cylinder 7 at one end, and is connected to the cold reservoir near the base 12 of the expander (e.g. to the cold reservoir shell 15 near the base 12 of the expander) by bonding, welding or other means, and the other end extends through the guide cylinder 7 and into the back pressure cavity 101, and the guide piston 8 and the guide cylinder 7 are in clearance fit; preferably, the guide piston 8 is a stepped shaft structure to form a two-section clearance sealing structure with the guide cylinder 7; the cold reservoir, the guide cylinder 7 and the guide piston 8 form a displacement assembly.

[0032] A magnetic spring assembly is arranged near the expansion cavity 33 to generate a magnetic force acting on the displacement assembly, and the direction of the magnetic force is opposite to the direction of the movement of the working gas driving the displacement assembly.

[0033] The cold finger cylinder 31, the cold reservoir shell 15, the guide cylinder 7 and the guide piston 8 are coaxially arranged.

[0034] The motor (including the stator assembly and the rotor assembly) of the Stirling refrigerator drives the eccentric rotating shaft to rotate, thereby driving the compression piston of the compressor assembly to reciprocate, so as to compress the working gas (e.g. helium). The compressed working gas enters the room temperature cavity 102 through the connecting pipe and the gas inlet hole 32, thereby driving the guide piston 8 and the cold reservoir to move synchronously inside the cold finger 3 and the guide cylinder 7 in a direction away from the back pressure cavity 101. At the same time, the compressed working gas enters the cold reservoir shell 15, exchanges heat with the energy storage material 6, so as to reduce the temperature of the gas working medium, thereby achieving heat exchange refrigeration. The gas working medium after heat exchange further enters the expansion cavity 33 to expand and refrigerate, and at the same time, the guide piston 8 and the cold reservoir of the displacement assembly move synchronously inside the cold finger 3 and the guide cylinder 7 in a direction close to the back pressure cavity 101. The expanded gas working medium can be reused by re-entering the compression cavity.

[0035] At the same time, when the guide piston 8 and the cold reservoir of the displacement assembly move synchronously under the driving of the gas working medium, the magnetic spring assembly generates a magnetic force acting in a direction opposite to the direction of the movement of the guide piston 8 and the cold reservoir, so as to provide a stable spring return force within the stroke range of the guide piston 8, thereby enabling the guide piston 8 to stably operate within the stroke range.

[0036] Therefore, in the embodiment, the magnetic spring assembly can replace the mechanical spring (e.g. plate spring, column spring, etc.) in the prior art to provide a spring return force, so as to ensure the stable movement of the guide piston within the stroke range, and at the same time, the axial or radial size of the expander can be reduced, thereby realizing the miniaturization of the expander, and avoiding the failure of the refrigerator due to the fatigue fracture risk of the mechanical spring.

[0037] Embodiment 2:

[0038] The difference between the present embodiment and embodiment 1 is only that the magnetic spring assembly comprises:

[0039] An internal magnetic member 5 is arranged inside the cold accumulator shell 15 near one end of the expansion cavity 33 and is connected with the inner wall of the cold accumulator shell 15 by means of bonding, welding or the like;

[0040] An external magnetic member 13 is arranged outside the cold finger cylinder 31 and corresponds to the position of the expansion cavity 33 and is connected with the outer wall of the cold finger cylinder 31 by means of bonding, welding or the like;

[0041] Further, the internal magnetic member 5 is in a ring-shaped integral structure or in a ring-shaped split structure formed by splicing a plurality of component units (such as a plurality of magnetic tiles), and / or the external magnetic member 13 is in a ring-shaped integral structure or in a ring-shaped split structure formed by splicing a plurality of component units (such as a plurality of magnetic tiles);

[0042] Meanwhile, the internal magnetic member 5 and the external magnetic member 13 are both permanent magnets (such as magnetic steel or the like), and as shown in the figure, the internal magnetic member 5 and the external magnetic member 13 are both magnetized in a radial manner and have the same magnetization direction (such as both outward along the radial direction or both inward along the radial direction); Figure 2

[0043] When the internal magnetic member 5 is in an initial position (for example, in the middle position of the external magnetic member 13), the resultant magnetic force exerted by the external magnetic member 13 on the internal magnetic member 5 is zero. When the internal magnetic member 5, the guide piston 8 and the cold accumulator move synchronously, the internal magnetic member 5 deviates from the initial position, the resultant magnetic force exerted by the external magnetic member 13 on the internal magnetic member 5 is not zero and the direction of the resultant magnetic force is opposite to the moving direction of the internal magnetic member 5, thereby generating a restoring effect similar to a mechanical spring. Further, in the present embodiment, the magnetic force can be adjusted by adjusting the size and material of the internal magnetic member 5 and the external magnetic member 13.

[0044] ​Thus, the embodiment makes full use of the internal space of the cold accumulator shell 15 and the external space of the cold finger cylinder 31 to arrange the magnetic members, so that the structure of the expander is more compact. At the same time, the magnetic force spring assembly is arranged as a whole at the cold end, i.e. near the expansion cavity 33, so that the internal magnetic member 5 and the external magnetic member 13 are continuously in a low-temperature environment, so as to continuously have a larger magnetic flux (compared to the case that the magnetic members are in a high-temperature environment), thereby avoiding the case that the magnetic flux of the magnetic members is attenuated due to the high-temperature environment, so that the rigidity of the magnetic force spring is reduced. At the same time, the long-time larger magnetic flux can further reduce the volume of the magnetic members, which is helpful to further reduce the overall volume of the product. In addition, when the internal magnetic member 5 and the external magnetic member 13 are installed by using the bonding method, since the internal magnetic member 5 and the external magnetic member 13 are in a low-temperature environment, the adhesive used for bonding can maintain the bonding performance for a long time, so as to avoid the magnetic members from falling off due to debonding.

[0045] Embodiment 3:

[0046] The difference between the embodiment and the embodiments 1 or 2 is only that the magnetic force spring assembly further comprises:

[0047] The internal magnetic member limiting member 4 is connected with the cold accumulator shell 15 by bonding, welding or the like, and is used for limiting the axial position of the internal magnetic member 5 and preventing the internal magnetic member 5 from falling out of the internal space of the cold accumulator shell 15;

[0048] and the external magnetic member limiting member 2 is connected with the outer wall surface of the cold finger cylinder 31 by bonding, welding or the like, and is used for limiting the axial position and / or radial position of the external magnetic member 13 and preventing the external magnetic member 13 from falling off;

[0049] For example, in the embodiment, the external magnetic member limiting member 2 comprises a radial limiting part 21 and / or an axial limiting part 22, wherein the radial limiting part 21 is located at the periphery of the external magnetic member 13 as a whole, and one end thereof is connected with the lower surface of the cold plate 1, and the axial limiting part 22 is located below the external magnetic member 13 as a whole, and one end thereof is connected with the outer wall surface of the cold finger cylinder 31.

[0050] Preferably, the external magnetic member limiting member 2 simultaneously has the radial limiting part 21 and the axial limiting part 22, and one end (i.e. the free end) of the radial limiting part 21 which is not connected with the cold plate 1 is connected with one end (i.e. the free end) of the axial limiting part 22 which is not connected with the outer wall surface of the cold finger cylinder 31, so as to form a structure with an “L” shape in the longitudinal section, and the radial limiting part 21 and the axial limiting part 22 can be integrally formed.

[0051] Embodiment 4:

[0052] The difference between the embodiment and any one of the embodiments 1-3 is only that the expander assembly further comprises:

[0053] A cylinder matching sealing piece is used to seal the matching part of the guide cylinder 7 and the cold finger 3, for example, the cylinder matching sealing piece in the embodiment includes a first sealing piece 9 used to seal the matching part of the end of the guide cylinder 7 away from the expander base 12 and the cold finger 3, and / or a second sealing piece 10 used to seal the matching part of the end of the guide cylinder 7 close to the expander base 12 and the cold finger 3; the cylinder matching sealing piece includes an O-shaped sealing ring.

[0054] And / or, a cold finger matching sealing piece 11 used to seal the matching part of the cold finger 3 and the expander base 12, preferably, the cold finger matching sealing piece 11 includes a C-shaped sealing ring or an O-shaped sealing ring.

[0055] Thus, different sealing pieces are used to seal the matching parts of different components, avoiding the influence of air leakage and air mixing on the refrigeration efficiency.

[0056] Embodiment 5:

[0057] The embodiment provides a Stirling refrigerating machine, which includes the expander assembly in any one of the embodiments 1-4.

[0058] In conclusion, the magnetic spring assembly is arranged as a whole at the cold end, so that the magnetic member is continuously in a low-temperature environment and continuously has a larger magnetic flux, thus avoiding the situation that the magnetic force spring stiffness becomes smaller due to the magnetic flux attenuation of the magnetic member in a high-temperature environment, and meanwhile, the long-time larger magnetic flux can further reduce the volume of the magnetic member, which is helpful to further reduce the overall volume of the product and make the product structure more compact, and in addition, since the magnetic member is in a low-temperature environment, the adhesive used for bonding can keep the bonding performance for a long time, avoiding the magnetic member from falling off due to debonding.

[0059] The above only describes the preferred embodiments of the present application and should not be used to limit the present application, and any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims

1. An expander assembly of a Stirling cryocooler comprising: An expander base, a cold finger in sealing connection with the expander base, and a pusher assembly located in the expander base and the cold finger, and an expansion cavity formed by the cold finger and the pusher assembly; The expander assembly further comprises: A magnetic spring assembly arranged close to the expansion cavity for generating a magnetic force applied to the pusher assembly, and the direction of the magnetic force is opposite to the direction of the movement of the pusher assembly; The magnetic spring assembly comprises: An internal magnetic member arranged in the inside of one end of a regenerator shell of the pusher assembly close to the expansion cavity, and connected with the inner wall of the regenerator shell; An external magnetic member arranged outside a cold finger cylinder of the cold finger, and connected with the outer wall of the cold finger cylinder at a position corresponding to the expansion cavity; An internal magnetic member limiting member connected with the regenerator shell for limiting the axial position of the internal magnetic member; The internal magnetic member and the external magnetic member are magnetized in a radial manner, and the magnetization directions are the same; The internal magnetic member and the external magnetic member are permanent magnets; The internal magnetic member is a whole ring structure or a split ring structure formed by splicing a plurality of component units, and / or the external magnetic member is a whole ring structure or a split ring structure formed by splicing a plurality of component units.

2. The expander assembly of claim 1, wherein, The magnetic spring assembly further comprises an external magnetic member limiting member connected with the outer wall of the cold finger cylinder for limiting the axial position and / or the radial position of the external magnetic member.

3. The expander assembly of claim 2, wherein, The external magnetic member limiting member comprises a radial limiting part located at the periphery of the external magnetic member, and one end of the radial limiting part is connected with the lower surface of a cold plate for closing the opening of the end of the cold finger cylinder, and / or an axial limiting part located below the external magnetic member, and one end of the axial limiting part is connected with the outer wall of the cold finger cylinder.

4. The expander assembly of claim 3, wherein, The free end of the radial limiting part and the free end of the axial limiting part are connected to form a structure with a longitudinal section in the shape of "L".

5. The expander assembly of claim 1, wherein, The expander assembly further comprises a cylinder matching sealing member for sealing the matching part of the guide cylinder of the pusher assembly and the cold finger.

6. The expander assembly of claim 1, wherein, The expander assembly further comprises a cold finger matching sealing member for sealing the matching part of the cold finger and the expander base.

7. A Stirling cryocooler characterised in that, An expander assembly comprising any one of claims 1-6.

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