CN116753636B

CN116753636B - Integrated free piston Stirling refrigerator device

Info

Publication number: CN116753636B
Application number: CN202311041936.4A
Authority: CN
Inventors: 巨永林; 谢世纪; 顾婉加; 李金超
Original assignee: Suzhou Hualeng Technology Co ltd
Current assignee: Suzhou Hualeng Technology Co ltd
Priority date: 2023-08-18
Filing date: 2023-08-18
Publication date: 2023-11-07
Anticipated expiration: 2043-08-18
Also published as: CN116753636A

Abstract

The application discloses an integral free piston Stirling refrigerator device, which comprises: ejector structure and power piston structure, and vibration damping assembly; the power piston structure comprises a power plate spring, a power bearing and a power piston which are sequentially arranged along the axial direction, wherein the power plate spring is fixedly connected with the power bearing; the ejector structure comprises a first piston, an ejector plate spring and a second piston which are sequentially arranged along the axial direction, wherein the ejector plate spring is connected with the first piston and the second piston through a first fastener, so that when the first piston and the second piston reciprocate under the action of air pressure difference, the ejector plate spring radially supports the first piston and the second piston; the device eliminates a connecting rod mechanism in a conventional ejector structure, greatly reduces the motion damping of the ejector, and simultaneously provides hundred watt-level cold energy in a temperature range of-196 ℃ to-80 ℃.

Description

Integrated free piston Stirling refrigerator device

Technical Field

The application relates to the technical field of refrigeration and low temperature, in particular to an integral free piston Stirling refrigerator device.

Background

With the rapid development of molecular biology and life sciences, a low-temperature environment through artificial manufacture plays an important role. The low-temperature storage technology has wide application in the fields of medicine, biology and the like: blood and blood products, special medicines, vaccines, human organs and biological samples. For the low-temperature preservation of biological samples, generally, the lower the temperature is, the longer the stable preservation time of the samples is, and the protection effect of different temperatures on the biological samples is different. The temperature of 80 ℃ below zero is the preservation temperature of a common biological sample, the DNA stability of cells at the temperature is better, most biological macromolecules such as RNA, protein, lipid and the like have certain stability at the temperature of 80 ℃ below zero, and the biological sample can be preserved for a plurality of months at the temperature. -196 ℃ is the liquid nitrogen temperature at which physiological and biochemical activities within the biological sample are substantially stopped and can be preserved for up to decades. The establishment of a low-temperature refrigerator and a low-temperature refrigerator in a temperature range of-196 ℃ to-80 ℃ requires a proper refrigeration mode.

For a temperature region of-196 ℃ to-80 ℃, the traditional single-stage vapor compression refrigeration can not reach the cryogenic temperature region, and the refrigeration can only be realized by a multi-stage cascade or mixed working medium self-cascade refrigeration technology with relatively complex structure, and the refrigeration coefficient is lower. The vapor compression type refrigerator has the advantages of huge volume, complex structure and low efficiency in a cryogenic temperature zone, and the used chlorofluorocarbon refrigerant has certain negative effects on ozone damage and global warming. The Stirling refrigeration principle is based on reverse Stirling cycle, the compressible gas with alternating flow is utilized for expansion refrigeration, the theoretical efficiency is Carnot efficiency, the working medium in the system is generally pollution-free inert gas helium, no phase change is caused in the operation process, a gap seal is adopted in a sealing mode, and the Stirling refrigerator has the advantages of low vibration, compact structure, small volume, energy conservation, environment friendliness, high reliability, long service life, refrigeration Wen Ouan and the like.

Since the proposed free piston stirling cooler, the structural design of the ejector has been a key to determine the cooling effect and overall structure. The prior art ejector structure mainly comprises an ejector, a compression chamber and a thin rod, wherein the thin rod penetrates through a power piston, the thin rod penetrates through the power piston and the linear motor, and the tail end of the thin rod is fixedly connected with the discharge plate spring fixed in the back pressure cavity to form a free piston. The piston rod penetrating structure has the defects that mutual motion interference is easy to generate between the power piston and the ejector, the damping of the ejector is increased, the refrigeration effect is reduced, the design difficulty of the power piston is increased, the stability is low, and the installation difficulty is high.

Therefore, the application has the urgent need to develop an integral free piston Stirling refrigerator device which eliminates the connecting rod mechanism in the conventional ejector structure, greatly reduces the motion damping of the ejector, provides hundred watt-level cold in the temperature range of-196 ℃ to-80 ℃ at the same time, and has the advantages of high refrigeration efficiency, environmental friendliness, long service life and small vibration.

Disclosure of Invention

The application aims to provide an integral free piston Stirling refrigerator device which eliminates a connecting rod mechanism in a conventional ejector structure, greatly reduces the motion damping of the ejector, simultaneously provides hundred watt-level cold energy in a temperature range of-196 ℃ to-80 ℃, and has the advantages of high refrigeration efficiency, environmental friendliness, long service life and small vibration.

A first aspect of the application provides an integral free piston stirling cooler device comprising:

comprising the following steps: an ejector structure and a power piston structure, wherein,

the power piston structure comprises a power plate spring, a power bearing and a power piston which are sequentially arranged along the axial direction, wherein the power plate spring is connected with the power bearing;

the ejector structure includes a first piston, an ejector plate spring, and a second piston sequentially disposed in an axial direction,

wherein the discharge plate spring is connected with the first piston and the second piston through a first fastener, so that the discharge plate spring radially supports the first piston and the second piston and provides axial rigidity for the first piston and the second piston when the first piston and the second piston reciprocate under the action of air pressure difference;

in the refrigerating process, high-pressure gas flows back and forth in an expansion cavity at one end of the second piston, which is far away from the discharge plate spring, and a compression cavity between the first piston and the power piston, and the gas in the expansion cavity performs positive work on the ejector structure, so that refrigeration is provided.

In another preferred embodiment, the ejector structure and power piston structure comprise a cylinder assembly and a piston assembly of the refrigerator appliance.

In another preferred embodiment, the cylinder assembly comprises a first cylinder, a second cylinder and a cylinder base, wherein the cylinder base is positioned above the first cylinder, the upper end of the first cylinder is coaxially inserted into the cylinder base, and the lower end of the first cylinder is coaxially inserted into the second cylinder; the two ends of the discharge plate spring are fixedly connected with the first cylinder or the second cylinder, so that the first piston reciprocates in the first cylinder, the second piston reciprocates in the second cylinder, and the power piston slides in the first cylinder.

In another preferred embodiment, the discharge plate spring is located between the first piston and the second piston.

In another preferred embodiment, the discharge plate spring is a double discharge plate spring.

In another preferred embodiment, the central axes of the first piston and the second piston are on the same straight line.

In another preferred embodiment, the central axes of the first piston and the second piston pass through the center point circle center of the discharge plate spring.

In another preferred embodiment, the discharge plate spring is fixedly connected to the first piston and the second piston by a first fastener.

In another preferred embodiment, the first piston, the second piston, and the discharge plate spring are coaxially mounted.

In another preferred embodiment, the first piston includes a cylindrical structure with a convex bottom surface, the second piston includes a cylindrical structure with a convex bottom surface, the first piston includes a first convex bottom surface protruding toward the discharge plate spring, and the second piston includes a second convex bottom surface protruding toward the discharge plate spring.

In another preferred embodiment, the ejector structure further includes a first fastener, the first convex bottom surface is provided with a first protrusion, the second convex bottom surface is provided with a second protrusion, and the first fastener passes through the ejector plate spring and is connected with the first protrusion and the second protrusion, thereby fixedly connecting the ejector plate spring with the first piston and the second piston.

In another preferred embodiment, the first projection is located at the center of the first projection bottom surface, and the first projection is a cylindrical structure extending toward the discharge plate spring.

In another preferred embodiment, the second projection is located at the center of the second projection bottom surface, and the second projection is a cylindrical structure extending toward the discharge plate spring.

In another preferred embodiment, the first fastener is a stud.

In another preferred embodiment, the first protruding portion is a cylindrical structure with internal threads inside, the second protruding portion is a cylindrical structure with internal threads inside, the internal threads are matched with the external threads of the stud to complete connection, and preferably, a proper amount of thread compound is coated when the first protruding portion and the second protruding portion are in threaded connection with the stud.

In another preferred embodiment, when the connection of the discharge plate spring with the first projection and the second projection by the first fastener is completed, the end face of the first projection is fitted to one surface of the discharge plate spring, and the end face of the second projection is fitted to the other surface of the discharge plate spring.

In another preferred embodiment, the maximum axial distance of the first convex bottom surface of the first piston from the ejector plate spring should be greater than the maximum amplitude of the ejector structure, and the maximum axial distance of the second convex bottom surface of the second piston from the ejector plate spring should also be greater than the maximum amplitude of the ejector structure.

In another preferred embodiment, the ejector structure further comprises a first cylinder and a second cylinder, and two ends of the ejector plate spring are fixedly connected with the first cylinder or the second cylinder, so that the first piston reciprocates in the first cylinder, and the second piston reciprocates in the second cylinder.

In another preferred embodiment, the ends of the two ends of the exhaust plate spring far from the center are fixedly connected with the end face of the first cylinder through a second fastener.

In another preferred embodiment, the second fastener is a socket head cap screw.

In another preferred embodiment, the second cylinder comprises a connecting section and a receiving section, the connecting section being located outside the first cylinder in the radial direction of the cylinder, the connecting section being gap-sealed with the first cylinder.

In another preferred embodiment, the first cylinder and the second cylinder are gap sealed by a cylinder seal.

In another preferred embodiment, an interface between the connection section of the second cylinder and the first cylinder is coated with adhesive, thereby fixing the second cylinder and the first cylinder.

In a further preferred embodiment, the first cylinder is inserted into the connecting section of the second cylinder.

In another preferred embodiment, a plurality of grooves are formed in the inner wall of the accommodating section, so that the air leakage amount between the compression cavity and the expansion cavity passing through gaps is reduced, and the sealing effect is positively achieved.

In another preferred embodiment, the positional relationship of the first piston, the second piston and the discharge plate spring is required to satisfy the following formula:

。

wherein m1 is the mass of the first piston, m2 is the mass of the second piston, L1 is the axial distance between the first piston center point and the discharge plate spring center point along the axial direction of the first piston, L2 is the axial distance between the second piston center point and the discharge plate spring center point along the axial direction of the second piston, g is the gravitational acceleration, k is the radial stiffness of the discharge plate spring,is the height of the air gap between the outer wall surface of the first piston and the inner wall surface of the first cylinder.

In another preferred embodiment, the power piston is designed as a hollow structure, the power piston comprising a power piston housing and a power piston end cap,

the first piston is designed to be of a hollow structure and comprises a first piston outer shell and a first piston top cover, the first piston outer shell and the first piston top cover are sealed through a first piston sealing piece, and the first piston outer shell is of a cylindrical structure with a convex bottom surface;

The second piston is designed to be of a hollow structure and comprises a second piston outer shell and a second piston top cover, and the second piston outer shell and the second piston top cover are fixedly connected and sealed through threads; the second piston outer shell is of a cylindrical structure with a convex bottom surface.

In another preferred embodiment, the first piston outer housing and the first piston cap are secured by a first piston fastener.

In another preferred embodiment, the first piston outer housing has a cylindrical structure with a bottom surface.

In another preferred embodiment, the second piston outer housing has a cylindrical structure with a bottom surface.

In another preferred embodiment, the first piston outer housing and the second piston outer housing are disposed adjacent to and opposite the discharge plate spring.

In another preferred embodiment, the first piston is made of an aluminum alloy material and the second piston is made of an engineering plastic.

In another preferred embodiment, the outer surface of the first piston is sprayed with a wear resistant lubricating coating, preferably a teflon coating.

In another preferred embodiment, the first cylinder is made of an aluminum alloy material and the second piston is made of an engineering plastic.

In another preferred embodiment, the inner cylinder wall surface of the first cylinder is polished and hard oxidized.

In another preferred embodiment, the device further comprises a vibration reduction assembly located above the ejector structure and the power piston structure, the vibration reduction assembly comprising a power vibration reduction mechanism for eliminating vibrations at the fundamental frequency of the refrigerator and a damping vibration reduction mechanism for reducing vibrations at high frequencies; the damping vibration attenuation mechanism is positioned above the dynamic vibration attenuation mechanism.

In another preferred embodiment, the power vibration reduction mechanism comprises a plurality of groups of power vibration reduction plate springs, balancing weights and power vibration reduction large screws, and the power vibration reduction plate springs and the balancing weights are fixed together through the power vibration reduction large screws;

the damping vibration attenuation mechanism comprises a damping filler, a damping disc, a backing ring, a damping vibration attenuation plate spring and a damping vibration attenuation big screw which are sequentially arranged along the axial direction, and the damping vibration attenuation plate spring, the backing ring and the damping disc are fixedly connected through the damping vibration attenuation big screw.

In another preferred embodiment, the device further comprises a shell component and a cold finger component arranged at the lower end of the shell component, wherein the vibration reduction component, the ejector structure and the power piston structure are arranged in the shell component and the cold finger component, and the cold finger component comprises a cold finger base, a hot end heat dissipation copper ring, a heat regenerator shell, a cold end heat dissipation copper ring and a cold finger end cover which are coaxially and sequentially connected into a whole; and the hot end heat dissipation filler, the heat regenerator, the cold end heat dissipation filler, the hot end limiting steel ring, the heat regenerator limiting ring and the cold end limiting steel ring are sequentially arranged along the axial direction.

In another preferred embodiment, the hot-end heat dissipation filler, the heat regenerator and the cold-end heat dissipation filler are arranged between the second cylinder and the hot-end heat dissipation copper ring, the heat regenerator shell and the cold-end heat dissipation copper ring;

the hot end limiting steel ring, the heat regenerator limiting ring and the cold end limiting steel ring are respectively used for fixing the hot end radiating filler, the heat regenerator and the cold end radiating filler.

In another preferred embodiment, the air cylinder further comprises a linear motor assembly, wherein the linear motor assembly is positioned above the air cylinder base and comprises an outer magnetic yoke, a permanent magnet rotor, an inner magnetic yoke and a coil.

In another preferred example, the permanent magnet mover comprises a permanent magnet, a lower permanent magnet supporting ring, an upper permanent magnet supporting ring and a transmission connecting disc.

In another preferred embodiment, an outer yoke upper support ring is arranged at the upper end of the outer yoke, an outer yoke lower support ring is arranged at the lower end of the outer yoke, and the outer yoke upper support ring, the outer yoke and the outer yoke lower support ring are axially stacked and fixed on the cold finger base.

In another preferred embodiment, the permanent magnet rotor and the power bearing are fixed together through a fastening nut, the power plate spring is arranged on the support ring on the outer magnetic yoke, the power plate spring and the support ring on the outer magnetic yoke are fastened together through a third screw, and the inner magnetic yoke is fixed on the cylinder base.

In another preferred embodiment, the housing assembly includes an annular housing and a housing end cover, the lower end surface of the annular housing is fixedly connected with the cold finger base and the cold finger base, and the upper end surface of the annular housing is fixedly connected with the housing end cover.

In another preferred embodiment, the housing assembly further comprises a connection terminal for accessing the lead wire of the coil, the connection terminal being disposed on one side of the annular housing, and an inflation copper tube disposed on the other side of the annular housing.

A second aspect of the present application provides an integral free piston stirling cooler device comprising a vibration reduction assembly wherein the vibration reduction assembly is located above the ejector structure and the power piston structure, the vibration reduction assembly comprising a power vibration reduction mechanism for eliminating refrigerator fundamental frequency vibrations and a damping vibration reduction mechanism for reducing high frequency vibrations; the damping vibration reduction mechanism is positioned above the dynamic vibration reduction mechanism;

the dynamic vibration reduction mechanism comprises a plurality of groups of dynamic vibration reduction plate springs, balancing weights and dynamic vibration reduction large screws, and the dynamic vibration reduction plate springs and the balancing weights are fixed together through the dynamic vibration reduction large screws;

In another preferred embodiment, the ejector structure further comprises an ejector structure and a power piston structure, wherein the power piston structure comprises a power plate spring, a power bearing and a power piston which are sequentially arranged along the axial direction, and the power plate spring is connected with the power bearing;

in the refrigerating process, high-pressure gas flows back and forth in an expansion cavity at one end of the second piston far away from the discharge plate spring and a compression cavity at one end of the first piston far away from the discharge plate spring, and the gas in the expansion cavity performs positive work on the ejector structure, so that refrigeration is provided.

In another preferred embodiment, the cold finger assembly further comprises a shell assembly and a cold finger assembly arranged at the lower end of the shell assembly; the vibration reduction assembly, the ejector structure and the power piston structure are arranged in the shell assembly and the cold finger assembly, and the cold finger assembly comprises a cold finger base, a hot end heat dissipation copper ring, a heat regenerator shell, a cold end heat dissipation copper ring and a cold finger end cover which are coaxially and sequentially connected into a whole; and the hot end heat dissipation filler, the heat regenerator, the cold end heat dissipation filler, the hot end limiting steel ring, the heat regenerator limiting ring and the cold end limiting steel ring are sequentially arranged along the axial direction.

In another preferred embodiment, the housing assembly comprises an annular housing and a housing end cover, wherein the lower end surface of the annular housing is fixedly connected with the cold finger base, and the upper end surface of the annular housing is fixedly connected with the housing end cover.

In another preferred embodiment, the first piston includes a cylindrical structure with a convex bottom surface, the second piston includes a cylindrical structure with a convex bottom surface, the first piston includes a first convex bottom surface protruding toward the discharge plate spring, and the second piston includes a second convex bottom surface protruding toward the discharge plate spring. In another preferred embodiment, the ejector structure further includes a first fastener, the first convex bottom surface is provided with a first protrusion, the second convex bottom surface is provided with a second protrusion, and the first fastener passes through the ejector plate spring and is connected with the first protrusion and the second protrusion, thereby fixedly connecting the ejector plate spring with the first piston and the second piston.

the second piston is designed to be of a hollow structure, the second piston comprises a second piston outer shell and a second piston top cover, the second piston outer shell and the second piston top cover are fixedly connected and sealed through threads, and the second piston outer shell is of a cylindrical structure with a convex bottom surface.

It is understood that within the scope of the present invention, the above-described technical features of the present invention and technical features specifically described below (e.g., in the examples) may be combined with each other to constitute new or preferred technical solutions. And are limited to a space, and are not described in detail herein.

Drawings

In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below. It is to be understood that the drawings described below are merely examples of embodiments of the present application and that other embodiments may be made by those skilled in the art without inventive effort.

FIG. 1 is a schematic diagram of an integrated free piston Stirling cooler device in accordance with an embodiment of the application;

FIG. 2 is a schematic diagram of an ejector configuration of a free piston Stirling refrigerator device in accordance with an embodiment of the application;

FIG. 3 is a schematic cross-sectional view of the ejector structure of a free piston Stirling cooler device in accordance with an embodiment of the application;

fig. 4 is a schematic structural view of an ejector plate spring of the ejector structure according to an embodiment of the present application;

FIG. 5 is a schematic view of a vibration damping assembly according to an embodiment of the present application.

In the drawings, the marks are as follows:

1-a first piston; 10-a first convex bottom surface; 101-a first projection; 11-a first piston outer housing; 12-a first piston cap; 13-a first piston seal; 14-a first piston fastener;

2-a second piston; 20-a second convex bottom surface; 201-a second protrusion; 21-a second piston outer housing; 22-a second piston cap;

3-discharge plate spring; 31-a first fastener; 32-a second fastener;

40-cylinder base; 41-a first cylinder; 42-a second cylinder; 43-cylinder seal; 421-connecting segment; 422-a receiving section; 4221-grooves;

51-power plate spring; 52-a dynamic bearing; 53-a power piston housing; 54-power piston end cap; 55-fastening tabs;

61-dynamic damper plate springs; 62-balancing weight; 63-dynamic vibration reducing large screw; 64-a first weld ring; 65-first screws;

71-damping filler; 72-damping disk; 73-backing ring; 74-damping vibration attenuation plate springs; 75-damping vibration attenuation big screw; 76-a second weld ring; 77-second screw;

81-cold finger base; 82-a hot-end heat dissipation copper ring; 83-regenerator housing; 84-cold end radiating copper ring; 85-cold finger end caps; 86-hot end heat dissipation filler; 87-regenerator; 88-cold end heat radiation filler; 89-a hot end limiting steel ring; 810-a regenerator stop collar; 811-a cold end limiting steel ring;

91-an outer yoke; 911-a support ring on the outer yoke; 912-an outer yoke lower support ring; 92-an inner yoke; 93-coil; 94-permanent magnets; 95-a permanent magnet lower support ring; 96-a support ring on the permanent magnet; 97-drive connection disc; 98-tightening a nut; 99-a third screw;

1001-an annular housing; 1002-housing end cap; 1003-connection terminal; 1004-inflating copper tubes;

l1-an axial distance between a first piston center point and a discharge plate spring center point along the axial direction of the first piston;

l2-the axial distance between the second piston center point and the discharge plate spring center point along the axial direction of the second piston;

delta-the height of the air gap between the outer wall surface of the first piston and the inner wall surface of the first cylinder.

Detailed Description

Through extensive and intensive research, the inventor firstly develops an integral free piston Stirling refrigerator device, and the device ensures that the vibration damping assembly can eliminate the vibration of the fundamental frequency of the refrigerator and weaken the high-frequency vibration by arranging a dynamic vibration damping mechanism and a damping vibration damping mechanism, thereby enhancing the stability of the refrigerator device; meanwhile, the device is provided with a unique ejector structure, the structure abandons the long and thin connecting rod structure of the ejector plate spring known in the prior art, eliminates direct interference and abrasion of the ejector and other parts of the refrigerator, greatly reduces friction damping, simultaneously combines the characteristics of air tightness, low axial heat conduction and low quality, and has better refrigerating effect.

As used herein, "ejector" and "ejector structure" are used interchangeably.

As used herein, "housing," "housing," and "outer housing" are used interchangeably.

As used herein, "axial distance" refers to a distance in the axial direction of the first piston or the second piston.

As used herein, "warm end piston", "warm end drain piston" and "first piston" refer to the same component;

as used herein, "cold end piston", "cold end discharge piston", and "second piston" refer to the same component;

as used herein, "first cylinder" and "hot end cylinder" refer to the same component;

as used herein, "second cylinder" and "cold end cylinder" refer to the same component;

it should be noted that in the present patent application, relational terms such as first and second, and the like are used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Moreover, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising" does not exclude the presence of other like elements in a process, method, article, or apparatus that comprises the element. In the present patent application, if it is mentioned that an action is performed according to an element, it means that the action is performed at least according to the element, and two cases are included: the act is performed solely on the basis of the element and is performed on the basis of the element and other elements. Multiple, etc. expressions include 2, 2 times, 2, and 2 or more, 2 or more times, 2 or more.

In the present application, all directional indications (such as up, down, left, right, front, rear, etc.) are merely used to explain the relative positional relationship, movement conditions, etc. between the components under a certain specific posture (as shown in the drawings), and if the specific posture is changed, the directional indication is changed accordingly.

The main advantages of the application

(a) The refrigerator device of the application can eliminate the vibration of the fundamental frequency of the refrigerator and weaken the high-frequency vibration by arranging the dynamic vibration reduction mechanism and the damping vibration reduction mechanism;

(b) The combination mode of the dynamic vibration reduction mechanism and the damping vibration reduction mechanism of the refrigerator device improves the vibration reduction effect of the refrigerator, enhances the stability of the refrigerator device, and is suitable for working environments with high vibration requirements;

(c) The ejector structure of the application eliminates the long and thin connecting rod structure of the ejector plate spring known in the prior art, and greatly reduces friction damping in the moving process by removing redundant parts except for the air cylinder, which can be directly worn with the ejector;

(d) The ejector structure eliminates direct interference and abrasion between the ejector piston and other parts of the refrigerator, and improves the refrigeration efficiency and stability of the refrigerator;

(e) According to the ejector structure, the ejector plate spring is arranged between the first piston and the second piston, so that the problem that the distance between the ejector plate spring and the ejector piston is overlarge in the prior art is solved, the coaxiality of the whole ejector is easy to control, the installation difficulty is reduced, and the stability is high;

(f) The ejector structure of the application has smaller volume, reduces the weight of the refrigerator and reduces the installation difficulty.

In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present application. However, it will be understood by those skilled in the art that the claimed application may be practiced without these specific details and with various changes and modifications from the embodiments that follow.

The ejector is an important structure of the free piston Stirling refrigerator, and plays a role in regulating the flow of working medium in the refrigerator. The stirling cooler is a process of alternately oscillating a compression piston and an ejector, with high pressure gas (helium) flowing back and forth between a compression chamber, a hot side heat sink, a regenerator, a cold side heat exchanger, and an expansion chamber. In one cycle of the operation of the refrigerator, the gas in the expansion cavity performs positive work on the ejector and generates refrigerating capacity in the expansion cavity, and meanwhile, the ejector transmits the work performed by the gas in the expansion cavity to the compression cavity, so that the effect of recovering sound work is achieved, and the refrigerating efficiency of the refrigerator is improved.

The free piston stirling cooler is a pneumatic cooler in that the displacement of the ejector in the cooler is caused by the pressure differential between the compression and expansion chambers and no additional force is applied to drive its movement and phase modulation of the internal gas. For free piston Stirling refrigerators, the ejector is directly connected to the ejector plate spring and is independent of the compression system, i.e. a "free" piston. The mass of the ejector, the stiffness of the ejector plate spring and the amount of damping during movement of the ejector play a key role in the phasing function of the ejector.

The application provides an ejector structure for a free piston Stirling refrigerator, which adopts a double-cylinder-double-ejector, can reduce damping in the movement process of the ejector, reduces axial heat conduction from a hot end to a cold end through a cylinder and the ejector (for example, a second piston is made of engineering plastic materials and has small heat conductivity coefficient), reduces air leakage of a compression cavity and an expansion cavity through the ejector, ensures stable operation of the ejector, reduces installation difficulty, and improves the stability and refrigeration efficiency of the refrigerator.

Integrated free piston Stirling refrigerator device

Referring to fig. 1, the refrigerator device of the present application includes a housing assembly, a cold finger assembly disposed at a lower end of the housing assembly, a power piston structure, an ejector structure, a vibration reduction assembly, and a linear motor assembly disposed in sequence in an axial direction. The vibration reduction assembly, ejector structure and power piston structure are disposed within the housing assembly and cold finger assembly. The piston assembly (first piston, second piston and power piston) included in the refrigerator device of the present application slides within the cylinder assembly (first cylinder, second cylinder), and the piston assembly and the cylinder assembly together constitute the ejector structure and the power piston structure of the refrigerator device described in the present application.

Vibration damping assembly

Referring to fig. 5, the vibration damping assembly is located above the ejector structure and the power piston structure, and the vibration damping assembly comprises a power vibration damping mechanism and a damping vibration damping mechanism, wherein the power vibration damping mechanism is used for eliminating vibration of a fundamental frequency of a refrigerator, and the damping vibration damping mechanism is used for damping high-frequency vibration; the damping vibration attenuation mechanism is positioned above the dynamic vibration attenuation mechanism.

The dynamic vibration reducing mechanism comprises a plurality of groups of dynamic vibration reducing plate springs 61, balancing weights 62 and dynamic vibration reducing large screws 63, and the dynamic vibration reducing plate springs 61 and the balancing weights 62 are fixed together through the dynamic vibration reducing large screws 63; the damping vibration attenuation mechanism comprises a damping filler 71, a damping disc 72, a backing ring 73, a damping vibration attenuation plate spring 74 and a damping vibration attenuation big screw 75 which are sequentially arranged along the axial direction, and the damping vibration attenuation plate spring 74, the backing ring 73 and the damping disc 72 are fixedly connected through the damping vibration attenuation big screw 75.

The vibration damping assembly is formed by combining a dynamic vibration damping mechanism and a damping vibration damping mechanism, the dynamic vibration damping mechanism is used for eliminating the vibration of the fundamental frequency of the refrigerator, the damping vibration damping mechanism is used for weakening the high-frequency vibration of the refrigerator, the structure is simple, the installation difficulty is low, the vibration of the refrigerator is greatly reduced, and the vibration damping assembly can be used for working in an environment with high vibration requirements.

Other components

The cold finger assembly comprises a cold finger base 81, a hot end heat dissipation copper ring 82, a regenerator shell 83, a cold end heat dissipation copper ring 84 and a cold finger end cover 85 which are coaxially and sequentially connected into a whole; and a hot end heat radiation filler 86, a heat regenerator 87, a cold end heat radiation filler 88, a hot end limit steel ring 89, a heat regenerator limit ring 810 and a cold end limit steel ring 811 which are sequentially arranged along the axial direction.

The linear motor assembly is located above the cylinder base 40, and comprises an outer magnetic yoke 91, a permanent magnet rotor, an inner magnetic yoke 92 and a coil 93.

The shell assembly comprises an annular shell 1001 and a shell end cover 1002, wherein the lower end face of the annular shell 1001 is fixedly connected with the cold finger base 81, and the upper end face of the annular shell 1001 is fixedly connected with the shell end cover 1002.

Ejector structure

Referring to fig. 2, the ejector structure includes a double cylinder (first cylinder 41, second cylinder 42), a double piston ejector (first piston 1 and second piston 2), an ejector plate spring 3; the discharge plate spring 3 is disposed between the first piston 1 and the second piston 2;

the first piston 1 and the second piston 2 are fixedly connected with the first piston 1, the second piston 2 and the discharge plate spring 3 through the first fastening piece 31, so that when the first piston 1 and the second piston 2 reciprocate under the action of air pressure difference, the discharge plate spring 3 radially supports the first piston 1 and the second piston 2 and provides axial rigidity for the first piston 1 and the second piston 2, high-pressure air reciprocates in an expansion cavity of one end, far away from the discharge plate spring 3, of the second piston 2 and a compression cavity between the first piston 1 and the power piston, and the air in the expansion cavity reciprocates in the expansion cavity of one end, far away from the discharge plate spring 3, of the first piston 1 and a compression cavity of one end, far away from the discharge plate spring 3, during refrigeration, and the air in the expansion cavity performs positive work on the ejector structure, so that refrigeration is provided.

In one embodiment, the first fastener 31 is a suitably sized stud. In one embodiment, the discharge plate spring 3 is a double discharge plate spring. In an embodiment, the central axes of the first piston 1 and the second piston 2 are collinear. In an embodiment, the central axes of the first piston 1 and the second piston 2 pass through the center point circle center of the discharge plate spring. In one embodiment, the discharge plate spring 3 is fixedly connected to the first piston 1 and the second piston 2 by a first fastener 31. In one embodiment, the first piston 1, the second piston 2 and the discharge plate spring 3 are coaxially installed.

Discharge plate spring

Referring to fig. 3 and 4, wherein fig. 3 shows a schematic cross-sectional view of the ejector structure of a free piston stirling cooler device; FIG. 4 shows a schematic view of the structure of an ejector plate spring of the ejector structure;

both ends of the discharge plate spring 3 are fixedly connected with the first cylinder 41 or the second cylinder 42, thereby realizing the reciprocating motion of the first piston 1 in the first cylinder 41 and the reciprocating motion of the second piston 2 in the second cylinder 42.

In one embodiment, both ends of the discharge plate spring 9 (ends away from the center of the discharge plate spring) are connected and fixed to the end face of the first cylinder 41 (end face toward the second cylinder 42) by the second fastener 32. In one embodiment, the second fastener 32 is a second socket head cap screw. In one embodiment, the edge (end) of the discharge plate spring 3 away from the center is connected to the first cylinder 41 by a screw.

First and second cylinders

Referring to fig. 2 to 4, the ejector structure of the present application takes the form of a double cylinder comprising a first cylinder 41 and a second cylinder 42, the first piston 1 reciprocating in the first cylinder 41 and the second piston 2 reciprocating in the second cylinder 42;

the second cylinder 42 comprises a connecting section 421 and a receiving section 422, said connecting section 421 being located outside the first cylinder 41 in the radial direction of the cylinder, so to speak, the first cylinder 41 being inserted into the connecting section 421 of said second cylinder 42, wherein the connecting section 421 is gap-sealed with said first cylinder 41.

In one embodiment, a plurality of grooves 4221 are provided on the inner wall of the accommodating section 422, which reduces the amount of air that can get through between the compression chamber and the expansion chamber, and has a positive effect on the sealing effect.

In one embodiment, first cylinder 41 and second cylinder 42 are gap sealed by cylinder seal 43. In one embodiment, the first cylinder 41 and the second cylinder 42 are gap sealed by O-ring seals and glued to the interface. In one embodiment, the interface between the connecting section 421 of the second cylinder 42 and the first cylinder 41 is coated with glue, thereby fixing the second cylinder 42 and the first cylinder 41.

For the first cylinder, the power piston (not shown) and the first piston vibrate reciprocally in the cylinder, so as to play a role of gas seal, and an air gap between the first cylinder and the first piston (hot end discharger piston) is small so as to ensure better air tightness.

First and second pistons

Referring to fig. 2-4, the first piston 1 comprises a cylindrical structure with a convex bottom surface, the second piston 2 comprises a cylindrical structure with a convex bottom surface, the first piston 1 comprises a first convex bottom surface 10 protruding towards the discharge plate spring 3, the second piston 2 comprises a second convex bottom surface 20 protruding towards the discharge plate spring 3, wherein the first convex bottom surface 10 and/or the second convex bottom surface 20 are arranged to avoid collision with the first piston 1 and/or the second piston 2 at the end or edge of the discharge plate spring 3, away from the centre, during movement of the piston.

In an embodiment, the ejector structure further includes a first fastening member 31, the first projecting bottom surface 10 is provided with a first projecting portion 101, the second projecting bottom surface 20 is provided with a second projecting portion 201, and the first fastening member 31 passes through the ejector plate spring 3 and is connected with the first projecting portion 101 and the second projecting portion 201, thereby fixedly connecting the ejector plate spring 3 with the first piston 1 and the second piston 2. In an embodiment, the first protrusion 101 is located at the center of the first protrusion bottom surface 10, and the first protrusion 101 has a cylindrical structure extending toward the discharge plate spring 3. In an embodiment, the second projection 201 is located at the center of the second projection bottom 20, and the second projection 201 has a cylindrical structure extending toward the discharge plate spring 3. In one embodiment, the first fastener 31 is a stud.

In an embodiment, the first protruding portion 101 is a cylindrical structure with internal threads inside, the second protruding portion 201 is a cylindrical structure with internal threads inside, and the internal threads are matched with the external threads of the stud to complete connection, and preferably, a proper amount of thread compound is coated when the first protruding portion 101 and the second protruding portion 201 are in threaded connection with the stud.

In an embodiment, when the connection of the discharge plate spring 3 with the first projection 101 and the second projection 201 by the first fastener 31 is completed, the end surface of the first projection 101 is fitted to one surface of the discharge plate spring 3, and the end surface of the second projection 201 is fitted to the other surface of the discharge plate spring.

In an embodiment, the axial distance of the first convex bottom surface 10 of the first piston 1 from the ejector plate spring 3 should be larger than the maximum amplitude of the ejector structure, and the axial distance of the second convex bottom surface 20 of the second piston 2 from the ejector plate spring 3 should also be larger than the maximum amplitude of the ejector structure.

For better air tightness, the first piston 1 should keep a small clearance with the first cylinder 41, but the first piston may deviate from the center position under the action of gravity and even contact the wall surface of the cylinder. In order to prevent the friction from increasing greatly due to the contact of the ejector with the wall surface, it is assumed that the geometric center of the first piston is spaced from the center axial distance (or axial distance) L1 of the center point of the first piston in the axial direction of the first piston from the center point of the discharge plate spring, the center axial distance L2 of the center point of the second piston (the second piston outer case 21 and the second piston top cover 22) in the axial direction of the second piston from the center axial distance L2 of the discharge plate spring, the weight m1 of the first piston 1, the weight m2 of the second piston 2, the radial stiffness of the discharge plate spring 3, the air gap between the first piston and the cylinder The relationship should be maintained in a certain way,

the positional relationship of the first piston 1, the second piston 2, and the discharge plate spring 3 may satisfy the following formula:

；/>。

wherein m1 is the mass of the hot end discharge piston, m2 is the mass of the cold end discharge piston, L1 is the axial distance between the position of the hot end discharge piston center and the center of the discharge plate spring, L2 is the axial distance between the position of the cold end discharge piston center and the center of the discharge plate spring, g is the gravitational acceleration, k is the radial stiffness of the discharge plate spring 9, and delta is the wall surface of the hot end discharge pistonAnd the air gap height between the hot end air cylinder and the inner wall surface of the hot end air cylinder. See FIG. 3, wherein L1, L2,Schematically shown.

(a) First piston

In order to reduce the quality of the ejector, the first piston 1 is of a hollow structure, the first piston 1 comprises a first piston outer shell 11 and a first piston top cover 12, the first piston outer shell 11 and the first piston top cover 12 are sealed by a first piston sealing piece 13, and the first piston outer shell 11 and the first piston top cover 12 are fixedly connected by a first piston fastening piece 14. In one embodiment, the first piston seal 13 is an O-ring seal. In one embodiment, the first piston fastener 14 is a socket head cap screw. Preferably, the first piston outer housing 11 is a cylindrical structure with a bottom surface.

In an embodiment, the first piston housing 11, the first piston top cover 12, the O-ring and the plurality of screws form a first piston assembly, the first piston housing 11 and the first piston top cover 12 are sealed by the O-ring to prevent loss of compression work caused by gas in the compression chamber entering and exiting the interior of the first piston assembly, and the first piston housing 11 and the first piston top cover 12 are fastened by eight screws.

In order to avoid direct collision of the first piston with the deformed discharge plate spring during movement, the side of the first piston housing near the cold end (second piston) or near the discharge plate spring 3 has a slope, the magnitude of which is determined by the maximum amplitude of the ejector assembly. In other words, the first piston housing comprises a first convex bottom surface 10 facing the ejector plate spring 3, whereby the bottom surface of the first piston housing is sloped and the first convex bottom surface 10 of the first piston 1 should be at a maximum axial distance from the ejector plate spring 3 that is greater than the maximum amplitude of the ejector structure; meanwhile, the first piston housing (hot end piston housing) of the ejector has a cylindrical boss (first protrusion 101) at a side close to the expansion chamber (or close to the discharge plate spring), and the center of the boss is formed with an internal thread to facilitate connection with the discharge plate spring 3 and the second piston 2.

(b) Second piston

In order to reduce the ejector mass, which is lighter, the second piston 2 is of hollow construction, preferably filled internally with a spoolable lightweight material in order to reduce the hollow volume and control the mass inside. The second piston 2 comprises a second piston outer shell 21 and a second piston top cover 22, and the second piston outer shell 21 and the second piston top cover 22 are fixedly connected and sealed through internal and external threads. Preferably, the first and second piston outer housings 11 and 21 are oppositely disposed near the discharge plate spring 3. Preferably, the second piston outer housing has a cylindrical structure with a bottom surface.

Likewise, in order to avoid that the second piston collides with the discharge plate spring during movement, the second piston housing has a slope on the side close to the discharge plate spring, which slope is dimensioned according to the maximum amplitude of the ejector assembly, i.e. the second piston housing comprises a second convex bottom surface 20 facing the discharge plate spring 3, whereby the bottom surface of the second piston housing is sloped, and the maximum axial distance of the second convex bottom surface 20 of the second piston 2 from the discharge plate spring 3 should be larger than the maximum amplitude of the ejector structure. The second piston outer housing has a boss (second projection 201) with an internally threaded hole of a certain depth in the center thereof against the discharge plate spring.

In one embodiment, a stud extends through the internal threads of the bosses (first protrusions 101) or bosses (second protrusions 201) of the first and second piston housings, and connects the discharge plate spring to the first and second piston housings and fixes the discharge plate spring to the screw surfaces by applying glue.

Power piston structure

The power piston structure comprises a power plate spring 51, a power bearing 52 and a power piston which are sequentially arranged along the axial direction, the power piston is arranged in the first cylinder 41 to slide in a reciprocating manner, the power piston is designed into a hollow structure, and the power piston comprises a power piston shell 53 and a power piston end cover 54; the power piston is arranged opposite to the first piston 1, and a compression cavity of gas is arranged between the power piston and the first piston 1 in the refrigerating process.

The power plate spring 51 is fixedly connected with the power bearing 52, and the power bearing 52 is fastened with the permanent magnet rotor of the linear motor assembly to form a whole.

Materials of each component

The ejector structure in the prior art consists of a single piston, the ejector penetrates through a compression cavity at the hot end and an expansion cavity at the cold end, the ejector structure generally selects aluminum alloy, stainless steel or high-molecular polymer (engineering plastic), and the ejector structure made of metal materials has the advantages of small thermal deformation, high strength, high processing precision and higher heat conductivity coefficient. The clearance between the air cylinder and the ejector can be designed to be small, the air tightness is good, and the shuttle loss and the pumping loss are small; however, the disadvantage is that the axial heat transfer from the compression chamber to the expansion chamber is greater and the mass of the ejector is also greater. For the high polymer material, the strength is generally lower, the processing precision is low, the thermal deformation amount is larger, and the heat conductivity coefficient is small; the device has the advantages that the axial heat conduction from the compression cavity to the expansion cavity through the ejector body is smaller, and the weight is lighter; the disadvantage is that a certain gap is kept between the ejector and the cylinder to prevent direct friction between the ejector and the cylinder due to temperature change, resulting in a great increase in the damping of the ejector.

The ejector structure adopts various problems (as described above) brought by single materials, and reduces axial heat conduction loss as far as possible while guaranteeing the air tightness (reducing shuttle loss and pumping loss) between the compression cavity and the expansion cavity so as to improve the high-efficiency refrigeration effect of the refrigerator.

Therefore, in order to reduce the heat transfer of the refrigerator from the hot end to the cold end through the cylinder, and simultaneously in order to maintain a small gap between the piston and the cylinder, in the technical scheme of the application, the cylinder structure and the ejector structure are both made of two materials in a mixed mode, wherein the first cylinder is made of metal materials such as aluminum alloy, stainless steel, titanium alloy and the like, the second cylinder is made of high-molecular polymers (engineering plastics) with low heat conductivity coefficient and high strength, and the first cylinder and the second cylinder are connected through an O-shaped sealing ring and are adhered by glue.

Preferably, the first piston 1 is made of an aluminum alloy material with higher strength and lower density, and the surface of the hot end discharge piston is uniformly sprayed with a Teflon and other wear-resistant lubricating coating. The second piston 2 is made of engineering plastics with small heat conductivity, low temperature resistance and low thermal expansion coefficient.

Preferably, the first cylinder 41 is made of an aluminum alloy material with high heat conductivity and high strength, wherein the inner cylinder wall surface of the first cylinder 41 is polished and hard oxidized.

The second cylinder 42 is made of engineering plastic with small heat conductivity, high strength and low thermal expansion coefficient, and the inner wall surface of the accommodating section 422 of the second cylinder 42 is of a sealing structure with multiple grooves 4221.

For the purpose of making the objects, technical solutions and advantages of the present invention more apparent, embodiments of the present invention will be described in further detail below with reference to the accompanying drawings. It should be understood that these are merely examples of what the reader may take and are not intended to limit the scope of the invention.

Examples

Integrated free piston Stirling refrigerator device

Referring to fig. 1, the embodiment provides an integral free piston stirling cooler device comprising a cold finger assembly, a linear motor assembly, a cylinder assembly, a piston assembly, a housing assembly, and a vibration damping assembly.

The piston assembly is comprised of a power piston structure, a discharge piston structure (described in detail below). The discharge piston structure consists of a first piston 1 (hot side discharge piston) and a second piston 2 (cold side discharge piston). The hot side discharge piston consists of a hot side discharge piston housing (first piston housing 11) and a hot side discharge piston end cover (first piston top cover 12), and the cold side discharge piston (second piston 2) consists of a cold side discharge piston housing (second piston housing 21) and a cold side discharge piston end cover (second piston top cover 22). The cold and hot end discharge pistons are designed to be hollow structures, the tail ends of the cold and hot end discharge pistons are provided with cylindrical bulges, internal threads are machined in the cylindrical bulges, and the cold and hot end discharge pistons are installed and fastened on two sides of the discharge plate spring 3 through studs (first fasteners 31). The cold end discharge piston is made of engineering plastic materials with light weight, small heat conductivity coefficient and low thermal expansion coefficient; the hot end discharging piston is made of aluminum alloy materials with high light weight, high strength and high hardness, and a Teflon coating is uniformly sprayed on the surface of the hot end discharging piston. The warm end discharge piston reciprocates in a first cylinder 41 (warm end cylinder) and the cold end discharge piston reciprocates in a second cylinder 42 (cold end cylinder). The power piston structure consists of a power plate spring (51), a power bearing 52 and a power piston. The power piston is designed as a hollow structure and consists of a power piston housing 53 and a power piston end cap 54. The power bearing 52 and the power piston are made of aluminum alloy materials with light weight and high strength. The power piston is fixedly connected with the power bearing 52 through screws, and is arranged in the hot end cylinder 41 to slide in a reciprocating manner.

The vibration damping assembly consists of a dynamic vibration damping mechanism and a damping vibration damping mechanism. The dynamic vibration damping mechanism is used for eliminating the vibration of the fundamental frequency of the refrigerator, and the damping vibration damping mechanism is used for weakening the high-frequency vibration. The dynamic vibration damping mechanism consists of a dynamic vibration damping plate spring 61, a balancing weight 62 and a dynamic vibration damping big screw 63. The center of the balancing weight 62 is drilled with an internal thread through hole, and the balancing weight 62 and the plurality of dynamic vibration reduction plate springs 61 are fastened into a whole by using a dynamic vibration reduction big screw 63. The inner side of the shell is welded with a first welding ring 64, a plurality of through holes are drilled on the outer ring of the dynamic vibration absorbing plate spring 61, and the dynamic vibration absorbing plate spring 61 is installed on the first welding ring 64 through a first screw 65 and a nut. The damping vibration attenuation mechanism comprises a damping filler 71, a damping disk 72, a backing ring 73, a damping vibration attenuation plate spring 74 and a damping vibration attenuation big screw 75 from top to bottom along the axial direction. A second weld ring 76 is welded to the inside of the housing. The damping filler 71 is composed of axially laminated copper wire mesh, and the damping filler 71 is adhered and fixed with the housing end cover 1002 by heat-conducting silica gel. The center of the damping disc 72 is drilled with a threaded hole, the damping plate spring 74, the backing ring 73 and the damping disc 72 are fixedly connected through a damping large screw 75, and the damping plate spring 74 is fixed on a second welding ring 76 through a second screw 77 and a nut.

The cold finger assembly consists of a cold finger end cover 85, a cold end heat dissipation copper ring 84, a heat regenerator shell 83, a hot end heat dissipation copper ring 82, a cold finger base 81, a cold end heat dissipation filler 88, a heat regenerator 87, a hot end heat dissipation filler 86, a cold end limit steel ring 811, a heat regenerator limit ring 810 and a hot end limit steel ring 89. The cold finger end cover 85, the cold end heat dissipation copper ring 84, the heat regenerator shell 83, the hot end heat dissipation copper ring 82 and the cold finger base 81 are coaxially arranged and welded into a whole by adopting a vacuum brazing mode, and the coaxiality is controlled within 0.005 mm. The hot end heat dissipation filler 86 and the cold end heat dissipation filler 88 are of folded copper sheet structures and are pressed into corresponding positions on the inner sides of the cold fingers by a hydraulic press; regenerator 87 is made of coiled high molecular polymer film or stainless steel wire gauze filler; the cold end limit steel ring 811, the regenerator limit ring 810, and the hot end limit steel ring 89 are pressed into corresponding positions in order to fix the cold and hot end heat dissipation fillers 88, 86 and the regenerator 87.

The cylinder assembly is made up of a first cylinder 41 (hot side cylinder), a second cylinder 42 (cold side cylinder), and a cylinder base 40. The hot end cylinder 41 is made of an aluminum alloy material with better heat conduction, and the cold end cylinder 42 is made of an engineering plastic material with light weight, small heat conduction coefficient and low thermal expansion coefficient. The hot side cylinder 41 is assembled coaxially with the cold side cylinder 42 and secured using glue. The inner surface of the cylinder base 40 is provided with a plurality of annular grooves, the hot end cylinder 41 is coaxially inserted into the cylinder base, and the sealing between the hot end cylinder 41 and the cylinder base 40 is realized through an O-shaped sealing ring. The bottom surface of the cylinder base 40 is drilled with a plurality of through holes, the upper end surface of the hot end cylinder 41 is processed with a plurality of screw holes, and the cylinder base 40 and the hot end cylinder 41 are connected and fixed by using screws. The cylinder base 40 is fastened to the cold finger 81 by a screw. The center of the hot side cylinder 41 is provided with a hollow groove so that the compression cavity forms a passage with the expansion cavity through the hot side heat radiation filler 86, the heat regenerator 87 and the cold side heat radiation filler 88.

The linear motor assembly comprises an outer magnetic yoke 91, a permanent magnet rotor, an inner magnetic yoke 92 and a coil 93. The permanent magnet mover consists of a permanent magnet 94, a permanent magnet lower support ring 95, a permanent magnet upper support ring 96 and a transmission connecting disc 97. The outer yoke 91, the outer yoke upper support ring 911, and the outer yoke lower support ring 912 are axially stacked and fixed on the cold finger base 81 by stud nuts; the annular permanent magnet 94, the permanent magnet lower support ring 95, the permanent magnet upper support ring 96 and the transmission connecting disc 97 are fastened into a whole through stud nuts, the radiation ring is magnetized integrally, the permanent magnet rotor and the power bearing 52 are fastened into a whole through the fastening nuts 98, and the power plate spring (51) is arranged on the upper support ring 911 of the outer magnetic yoke and fastened through the third screw 99. The center of the power plate spring 51 is provided with a round hole, the tail end surface of the power bearing 52 is provided with a plurality of internal threads, the tail end of the power bearing 52 penetrates through the round hole to enable the lower bottom surface of the power plate spring 51 to be attached to the upper end surface of the fastening nut 98, and the center of the power plate spring 51 is fastened with the power bearing 52 through the fastening piece 55 and the screw. The coil 93 is uniformly and tightly wound around the hollow portion of the inner yoke 92 to form a body, and the inner yoke 92 has a through-hole structure in the axial direction, and the inner yoke 92 is fixed to the cylinder base 40 by a stud nut. The center position deviation of the permanent magnet 94, the outer yoke 91, and the inner yoke 92 was controlled within 0.1 mm.

The housing assembly includes an annular housing 1001, housing end cap 1002, terminal block 1003, and gas filled copper tube 1004. One side of the annular housing 1001 is welded to the cold finger base 81 by argon arc welding, and the other side is welded to the housing end cap 1002 by argon arc welding. The side of the housing 1001 is processed with a through hole, the connection terminal 1003 is welded with the housing 1001 by energy storage welding, and two leads of the coil 93 are connected to the inner side of the connection terminal 1003 of the refrigerator. The other side of the housing 1001 has a circular hole, and the filler copper tube 1004 is welded to the housing 1001 by brazing. It is worth mentioning that all parts need to be dried in a drying oven for a certain time before being installed.

Ejector structure

The present embodiment also provides an ejector structure for a free piston stirling cooler device employing a dual cylinder-dual piston structure as shown in fig. 2-4, the device comprising: a first piston 1, a second piston 2, a discharge plate spring 3, a first cylinder 41, and a second cylinder 42.

Wherein the first piston 1, the second piston 2, the discharge plate spring 3 are arranged in the axial direction, the discharge plate spring 3 being arranged between the first piston 1 and the second piston 2. The discharge plate spring 3 is connected with the first piston 1 and the second piston 2 through the first fastener 31 such that the discharge plate spring 3 radially supports the first piston 1 and the second piston 2 and provides axial rigidity to the first piston 1 and the second piston 2 when the first piston 1 and the second piston 2 reciprocate under the action of the air pressure difference;

Specifically, referring to fig. 3, the first piston 1 includes a first piston outer case 11 and a first piston top cover 12, the first piston outer case 11 and the first piston top cover 12 being sealed by a first O-ring seal (i.e., one example of a first piston seal 13) and fixed by a first socket head cap screw (i.e., one example of a first piston fastener 14). The first piston outer shell 11 is of a cylindrical structure with a convex bottom surface, the first piston 1 comprises a first convex bottom surface 10 protruding towards the discharge plate spring 3, the first convex bottom surface 10 is provided with a cylindrical protrusion 101 (i.e. a first protrusion 101) facing the discharge plate spring 3, and the cylindrical center of the protrusion is provided with an internal thread;

the second piston 2 comprises a second piston outer housing 21 and a second piston top cover 22, and the second piston outer housing 21 and the second piston top cover 22 are fixedly connected and sealed through internal and external threads. The second piston housing body 21 is a cylindrical structure with a protruding bottom surface, the second piston housing body 21 includes a second protruding bottom surface 20 protruding toward the discharge plate spring 3, the second protruding bottom surface 20 is provided with a boss (i.e., a second protruding portion 201) facing the discharge plate spring 3, and the center of the boss has an internal threaded hole of a certain depth, so that the first piston 1, the second piston 2 and the discharge plate spring 3 are fixed by a stud connection of a proper size, and the stud passes through the protrusion (first protruding portion 101) of the first protruding bottom surface, the discharge plate spring 3, and the boss 201 (i.e., the second protruding portion 201) of the second protruding bottom surface 20. Wherein the mounting coaxiality of the first piston 1, the second piston 2 and the discharge plate spring 3 is controlled within 0.005 mm.

The discharge plate spring 3 is fixedly connected with the upper end surface of the first cylinder 41 by a second socket head cap screw (i.e., one example of the second fastener 32), and the coaxiality of the discharge plate spring 3 with the first cylinder 41 is controlled within 0.005 mm.

The first cylinder 41 and the second cylinder 42 are gap sealed by a second O-ring (i.e., one example of a cylinder seal 43) and are adhesively secured at their interfaces. Wherein the mounting coaxiality of the first cylinder 41 and the second cylinder 42 is controlled within 0.005 mm.

In this embodiment, the first piston 1 is made of an aluminum alloy material with higher strength and lower density, and the surface of the hot end discharge piston is uniformly sprayed with a wear-resistant lubricating coating such as teflon. The second piston 2 is made of engineering plastics with small heat conductivity, low temperature resistance and low thermal expansion coefficient. The first cylinder 1 is made of an aluminum alloy material with high heat conductivity coefficient and high strength, wherein the inner cylinder wall surface of the hot-end cylinder is polished and oxidized hard. The second cylinder 42 is made of engineering plastics with small heat conductivity, high strength and low thermal expansion coefficient, and the inner wall surface of the cylinder is of a multi-groove sealing structure.

An ejector structure mounting step:

(1) The O-shaped ring with proper size is sleeved at the boss of the first piston top cover, and the first piston top cover is connected and fixed with the first piston shell body through 8 screws.

(2) And uniformly filling the light material on the second piston outer shell, and then fixing the second piston top cover and the second piston through threads.

(3) A stud with proper size and length is penetrated into a round hole in the center of the discharge plate spring 3, the first piston and the second piston are connected through threads, the convex end surface of the second piston outer shell (namely, the end surface of the first convex part 101 of the first convex bottom surface 10) and the convex end surface of the first piston outer shell (namely, the end surface of the second convex part 201 of the first convex bottom surface 10) are flush and attached to two surfaces of the discharge plate spring, and proper amount of thread glue is coated during threaded connection. It should be noted that the coaxiality of the discharge plate spring, the first piston (the first piston outer housing 11 and the first piston top cover 12) and the second piston (the second piston outer housing 21 and the second piston top cover 22) should be maintained during the installation, and the coaxiality should be maintained within 0.005mm.

(4) The discharge plate spring was coaxially mounted on the end face of the first cylinder by eight screws, with the coaxiality required to be within 0.005mm.

(5) Finally, the first cylinder 41 and the second cylinder 42 are sealed by an O-shaped sealing ring, and a proper amount of anaerobic adhesive is filled in a gap between the first cylinder 41 and the second cylinder to ensure the fixation of the first cylinder and the second cylinder, and the coaxiality in the installation process is controlled to be 0.005mm.

It is worth mentioning that all parts need to be dried in a drying oven for a certain time before being installed.

The applicant wants to emphasize that the ejector structure of this embodiment abandons the method of using the ejector base placed in the compression chamber and arranging the ejector plate spring in the ejector, and will remove the unnecessary parts except the cylinder that can directly wear with the ejector, and when greatly reducing the damping, ensure good ejector and cylinder air tightness (shuttle loss and pumping loss are very little), do not increase the empty volume of compression chamber or expansion chamber, the ejector axial heat conduction is very little, do not influence the maximum power of refrigerator, simplify the refrigerator structure and guarantee safe and reliable operation of refrigerator when less installation degree of difficulty.

The numerous technical features described in the description of the present application are distributed among the various technical solutions, which can make the description too lengthy if all possible combinations of technical features of the present application (i.e., technical solutions) are to be listed. In order to avoid this problem, the technical features disclosed in the above summary of the application, the technical features disclosed in the following embodiments and examples, and the technical features disclosed in the drawings may be freely combined with each other to constitute various new technical solutions (these technical solutions are regarded as already described in the present specification) unless such a combination of technical features is technically impossible. For example, in one example, feature a+b+c is disclosed, in another example, feature a+b+d+e is disclosed, and features C and D are equivalent technical means that perform the same function, technically only by alternative use, and may not be adopted simultaneously, feature E may be technically combined with feature C, and then the solution of a+b+c+d should not be considered as already described because of technical impossibility, and the solution of a+b+c+e should be considered as already described.

All references mentioned in this disclosure are to be considered as being included in the disclosure of the application in its entirety so that modifications may be made as necessary. Further, it is understood that various changes or modifications of the present application may be made by those skilled in the art after reading the above disclosure, and such equivalents are intended to fall within the scope of the application as claimed.

Claims

1. An integrated free piston stirling cooler device comprising: an ejector structure and a power piston structure, wherein,

the power piston structure comprises a power plate spring (51), a power bearing (52) and a power piston which are sequentially arranged along the axial direction, wherein the power plate spring (51) is connected with the power bearing (52);

the ejector structure comprises a first piston (1), an ejector plate spring (3) and a second piston (2) which are sequentially arranged along the axial direction,

wherein the discharge plate spring (3) is connected with the first piston (1) and the second piston (2) by a first fastener (31) so that the discharge plate spring (3) radially supports the first piston (1) and the second piston (2) and provides axial rigidity to the first piston (1) and the second piston (2) when the first piston (1) and the second piston (2) reciprocate under the action of an air pressure difference;

In the refrigerating process, high-pressure gas flows back and forth in an expansion cavity at one end of the second piston (2) far away from the discharge plate spring (3) and a compression cavity between the first piston (1) and the power piston, and the gas in the expansion cavity performs positive work on the ejector structure, so that refrigerating is provided,

the device further comprises a linear motor assembly, wherein the linear motor assembly is positioned above the power piston, and the power plate spring (51) is arranged above the linear motor assembly;

the first piston (1) is of a hollow structure, the first piston (1) comprises a first piston outer shell (11) and a first piston top cover (12), the first piston outer shell (11) and the first piston top cover (12) are sealed through a first piston sealing piece (13), and the first piston outer shell (11) is of a cylindrical structure with a convex bottom surface; the second piston (2) is of a hollow structure, the second piston (2) comprises a second piston outer shell (21) and a second piston top cover (22), the second piston outer shell (21) and the second piston top cover (22) are fixedly connected and sealed through threads, and the second piston outer shell (21) is of a cylindrical structure with a convex bottom surface;

the first piston (1) comprises a first protruding bottom surface (10) protruding towards the discharge plate spring (3), the second piston (2) comprises a second protruding bottom surface (20) protruding towards the discharge plate spring (3), the ejector structure further comprises a first fastening piece (31), the first protruding bottom surface (10) is provided with a first protruding portion (101), the second protruding bottom surface (20) is provided with a second protruding portion (201), and the first fastening piece (31) penetrates through the discharge plate spring (3) and is connected with the first protruding portion (101) and the second protruding portion (201), so that the discharge plate spring (3) is fixedly connected with the first piston (1) and the second piston (2).

2. The chiller apparatus of claim 1, further comprising a vibration reduction assembly located above the ejector structure and power piston structure, the vibration reduction assembly comprising a power vibration reduction mechanism for eliminating vibrations at a chiller base frequency and a damping vibration reduction mechanism for reducing high frequency vibrations; the damping vibration attenuation mechanism is positioned above the dynamic vibration attenuation mechanism.

3. The refrigerator device according to claim 2, wherein the dynamic vibration absorbing mechanism comprises a plurality of groups of dynamic vibration absorbing plate springs (61), balancing weights (62) and dynamic vibration absorbing large screws (63), and the dynamic vibration absorbing plate springs (61) and the balancing weights (62) are fixed together through the dynamic vibration absorbing large screws (63);

the damping vibration attenuation mechanism comprises a damping filler (71), a damping disc (72), a backing ring (73), a damping vibration attenuation plate spring (74) and a damping vibration attenuation big screw (75) which are sequentially arranged along the axial direction, and the damping vibration attenuation plate spring (74), the backing ring (73) and the damping disc (72) are fixedly connected through the damping vibration attenuation big screw (75).

4. A refrigerator apparatus as claimed in claim 3, wherein the positional relationship of the first piston, the second piston and the discharge plate spring satisfies the following equation:

Wherein m1 is the mass of the first piston, m2 is the mass of the second piston, L1 is the axial distance between the first piston center point and the discharge plate spring center point along the axial direction of the first piston, L2 is the axial distance between the second piston center point and the discharge plate spring center point along the axial direction of the second piston, g is the gravitational acceleration, k is the radial stiffness of the discharge plate spring, and δ is the air gap height between the first piston outer wall surface and the first cylinder inner wall surface.

5. The refrigerator apparatus according to claim 4, wherein the ejector structure further comprises a first cylinder (41) and a second cylinder (42), both ends of the ejector plate spring (3) are fixedly connected to the first cylinder (41) or the second cylinder (42), thereby realizing a reciprocating motion of the first piston (1) in the first cylinder (41), a reciprocating motion of the second piston (2) in the second cylinder (42), and a sliding motion of the power piston in the first cylinder.

6. A refrigerator device according to claim 5, characterized in that the second cylinder (42) comprises a connecting section (421) and a receiving section (422), which connecting section is located outside the first cylinder (41) in the radial direction of the cylinder, the connecting section (421) being gap-sealed with the first cylinder (41), the receiving section (422) being provided with a plurality of grooves on its inner wall.

7. The refrigerator arrangement according to claim 6, characterized in that the power piston is designed as a hollow structure, which power piston comprises a power piston housing (53) and a power piston end cap (54).

8. The refrigerator apparatus of claim 7, further comprising a housing assembly, a cold finger assembly disposed at a lower end of the housing assembly; the vibration reduction assembly, the ejector structure and the power piston structure are arranged in the shell assembly and the cold finger assembly, and the cold finger assembly comprises a cold finger base (81), a hot end heat dissipation copper ring (82), a regenerator shell (83), a cold end heat dissipation copper ring (84) and a cold finger end cover (85) which are coaxially and sequentially connected into a whole; and the heat end heat dissipation filler (86), the heat regenerator (87), the cold end heat dissipation filler (88), the heat end limiting steel ring (89), the heat regenerator limiting ring (810) and the cold end limiting steel ring (811) are sequentially arranged along the axial direction.

9. The refrigerator appliance of claim 8, further comprising a linear motor assembly located above the cylinder base (40), the linear motor assembly comprising an outer yoke (91), a permanent magnet mover, an inner yoke (92), a coil (93).

10. The refrigerator apparatus of claim 9, wherein the housing assembly comprises an annular housing (1001) and a housing end cap (1002), a lower end surface of the annular housing (1001) is fixedly connected to the cold finger base (81), and an upper end surface of the annular housing (1001) is fixedly connected to the housing end cap (1002).