Integral type free piston Stirling cryocooler device

Abstract

The invention discloses an integral type free piston Stirling cryocooler device which comprises a discharger structure, a power piston structure and a vibration reduction assembly. The power piston structure comprises a power plate spring, a power bearing and a power piston which are sequentially arranged in the axial direction, and the power plate spring is fixedly connected with the power bearing; the discharger structure comprises a first piston, a discharging plate spring and a second piston which are sequentially arranged in the axial direction, and the discharging 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 discharging plate spring is connected with the first piston and the second piston. The discharge plate spring radially supports the first piston and the second piston; according to the device, a connecting rod mechanism in a conventional discharger structure is omitted, the movement damping of the discharger is greatly reduced, and meanwhile, hectowatt-level cooling capacity is provided within the temperature range from-196 DEG C to-80 DEG C.

Description

[0001] This application is a divisional application of the invention application with application date of August 18, 2023, application number 202311041936.4, and invention name “An integral free-piston Stirling refrigerator device”. Technical Field

[0002] The present application relates to the field of refrigeration and cryogenic technology, and in particular to an integral free piston Stirling refrigerator device. Background Art

[0003] With the rapid development of molecular biology and life sciences, artificially created low-temperature environments play an important role. Low-temperature storage technology has a wide range of applications in the fields of medicine and biology: the preservation of blood and blood products, special medicines, vaccines, human organs and biological samples. For the low-temperature preservation of biological samples, generally speaking, the lower the temperature, the longer the stable storage time of the sample, and different temperatures have different protective effects on biological samples. -80℃ is a commonly used biological sample storage temperature. At this temperature, the DNA stability of cells is good. Most biological macromolecules such as RNA, proteins and lipids have a certain stability at -80℃. Generally, biological samples can be stored for several months at this temperature. -196℃ is the temperature of liquid nitrogen. At this temperature, the physiological and biochemical activities in biological samples basically stop, and they can be stored for decades. The establishment of low-temperature cold storage and low-temperature refrigerators in the temperature range of -196℃ to -80℃ requires a suitable refrigeration method.

[0004] For the temperature range of -196℃~-80℃, traditional single-stage steam compression refrigeration often cannot reach this deep cold temperature range, and can only be achieved through relatively complex multi-stage cascade or mixed working fluid self-cascade refrigeration technology, with a low refrigeration coefficient. Steam compression refrigerators are not only bulky, complex in structure, and low in efficiency in deep cold temperature ranges, but the chlorofluorocarbon refrigerants they use have a certain negative impact on ozone destruction and global warming. The Stirling refrigeration principle is based on the reverse Stirling cycle, which uses the expansion refrigeration of the alternating flow of compressible gas. The theoretical efficiency is the Carnot efficiency. The working fluid inside the system is generally non-polluting inert gas helium. There is no phase change during the operation process, and the sealing method uses gap sealing. The Stirling refrigerator has the advantages of low vibration, compact structure, small size, energy saving and environmental protection, strong reliability, long service life and wide refrigeration temperature range.

[0005] Since the free piston Stirling refrigerator was proposed, the structural design of the displacer has always been the key to determining the cooling effect and the overall structure. The structure of the displacer in the current prior art is mainly that the displacer is connected to a thin rod that passes through the power piston near the compression chamber. The thin rod passes through the power piston and the linear motor. The end of the thin rod is connected and fixed to the discharge plate spring fixed in the back pressure chamber to form a free piston. The disadvantage of this piston-through-rod structure is that it is easy for the power piston and the displacer to cause mutual motion interference, increase the damping of the displacer, cause a decrease in the cooling effect, and increase the design difficulty of the power piston. The stability is not high and the installation is difficult.

[0006] Therefore, the present application urgently needs to develop an integral free piston Stirling refrigerator device, which eliminates the connecting rod mechanism in the conventional displacer structure, greatly reduces the damping of the displacer motion, and at the same time provides a cooling capacity of hundreds of watts in the temperature range of -196°C to -80°C, and has the advantages of high cooling efficiency, environmental friendliness, long life and low vibration. Summary of the invention

[0007] The purpose of the present application is to provide an integral free-piston Stirling refrigerator device, which eliminates the connecting rod mechanism in the conventional displacer structure, greatly reduces the damping of the displacer movement, and at the same time provides a cooling capacity of hundreds of watts in the temperature range of -196°C to -80°C, and has the advantages of high cooling efficiency, environmental friendliness, long life and low vibration.

[0008] The first aspect of the present application provides an integrated free piston Stirling refrigerator device comprising:

[0009] It includes: an ejector structure and a power piston structure, wherein:

[0010] The power piston structure comprises a power leaf spring, a power bearing and a power piston arranged in sequence along the axial direction, wherein the power leaf spring is connected to the power bearing;

[0011] The ejector structure comprises a first piston, a discharge plate spring, and a second piston which are sequentially arranged in the axial direction.

[0012] wherein the discharge plate spring is connected to 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 the gas pressure difference, the discharge plate spring radially supports the first piston and the second piston and provides axial stiffness for the first piston and the second piston;

[0013] During the refrigeration process, high-pressure gas flows back and forth in the expansion chamber of the second piston at one end away from the discharge plate spring and the compression chamber between the first piston and the power piston. The gas in the expansion chamber does positive work on the discharger structure, thereby providing refrigeration.

[0014] In another preferred example, the displacer structure and the power piston structure constitute a cylinder assembly and a piston assembly of the refrigerator device.

[0015] In another preferred example, the cylinder assembly includes a first cylinder, a second cylinder and a cylinder base, the cylinder base is located 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 to the first cylinder or the second cylinder, so as to realize the reciprocating motion of the first piston in the first cylinder, the reciprocating motion of the second piston in the second cylinder, and the sliding of the power piston in the first cylinder.

[0016] In another preferred example, the discharge plate spring is located between the first piston and the second piston.

[0017] In another preferred embodiment, the discharge leaf spring is composed of a double discharge leaf spring.

[0018] In another preferred example, central axes of the first piston and the second piston are on the same straight line.

[0019] In another preferred example, the central axes of the first piston and the second piston pass through the center point of the discharge leaf spring.

[0020] In another preferred example, the discharge leaf spring is fixedly connected to the first piston and the second piston via a first fastener.

[0021] In another preferred example, the first piston, the second piston and the discharge plate spring are coaxially installed.

[0022] In another preferred example, the first piston includes a cylindrical structure with a protruding bottom surface, the second piston includes a cylindrical structure with a protruding bottom surface, the first piston includes a first protruding bottom surface protruding toward the discharge leaf spring, and the second piston includes a second protruding bottom surface protruding toward the discharge leaf spring.

[0023] In another preferred example, the ejector structure further includes a first fastener, the first protruding bottom surface is provided with a first protruding portion, the second protruding bottom surface is provided with a second protruding portion, the first fastener passes through the ejection leaf spring and is connected to the first protruding portion and the second protruding portion, thereby fixing the ejection leaf spring to the first piston and the second piston.

[0024] In another preferred example, the first protrusion is located at the center of the first protruding bottom surface, and the first protrusion is a cylindrical structure extending toward the discharge plate spring.

[0025] In another preferred example, the second protrusion is located at the center of the second protrusion bottom surface, and the second protrusion is a cylindrical structure extending toward the discharge plate spring.

[0026] In another preferred example, the first fastener is a stud.

[0027] In another preferred example, the first protrusion is a cylindrical structure with an internal thread, and the second protrusion is a cylindrical structure with an internal thread. The internal thread cooperates with the external thread of the stud to complete the connection. Preferably, a proper amount of thread glue is applied when the first protrusion and the second protrusion are connected to the stud thread.

[0028] In another preferred example, when the discharge leaf spring is connected to the first protrusion and the second protrusion by the first fastener, the end surface of the first protrusion fits with one surface of the discharge leaf spring, and the end surface of the second protrusion fits with the other surface of the discharge leaf spring.

[0029] In another preferred example, the maximum axial distance between the first protruding bottom surface of the first piston and the discharge plate spring should be greater than the maximum amplitude of the discharger structure, and the maximum axial distance between the second protruding bottom surface of the second piston and the discharge plate spring should also be greater than the maximum amplitude of the discharger structure.

[0030] In another preferred example, the ejector structure further includes a first cylinder and a second cylinder, and both ends of the ejector leaf spring are fixedly connected to the first cylinder or the second cylinder, thereby realizing reciprocating motion of the first piston in the first cylinder and reciprocating motion of the second piston in the second cylinder.

[0031] In another preferred embodiment, the ends of both ends of the discharge leaf spring away from the center are fixedly connected to the end surface of the first cylinder through a second fastener.

[0032] In another preferred example, the second fastener is a hexagon socket screw.

[0033] In another preferred example, the second cylinder includes a connecting section and a containing section, the connecting section is located outside the first cylinder in the radial direction of the cylinder, and the connecting section is gap-sealed with the first cylinder.

[0034] In another preferred example, the first cylinder and the second cylinder are sealed by a cylinder seal gap.

[0035] In another preferred example, the interface between the connecting section of the second cylinder and the first cylinder is coated with glue, so as to fix the second cylinder and the first cylinder.

[0036] In another preferred example, the first cylinder is inserted into a connecting section of the second cylinder.

[0037] In another preferred embodiment, a plurality of grooves are arranged on the inner wall of the accommodating section to reduce the amount of air cross-talk between the compression chamber and the expansion chamber through the gap, which has a positive effect on the sealing effect.

[0038] In another preferred embodiment, the positional relationship between the first piston, the second piston and the discharge plate spring needs to satisfy the following formula:

[0039]

[0040]

[0041] Wherein, m1 is the mass of the first piston, m2 is the mass of the second piston, L1 is the axial distance between the center point of the first piston and the center point of the discharge leaf spring along the axial direction of the first piston, L2 is the axial distance between the center point of the second piston and the center point of the discharge leaf spring along the axial direction of the second piston, g is the acceleration of gravity, k is the radial stiffness of the discharge leaf spring, and δ is the air gap height between the outer wall surface of the first piston and the inner wall surface of the first cylinder.

[0042] In another preferred embodiment, the power piston is designed as a hollow structure, and the power piston includes a power piston housing and a power piston end cover.

[0043] The first piston is designed as a hollow structure, comprising a first piston outer shell and a first piston top cover, the first piston outer shell and the first piston top cover are sealed by a first piston seal, and the first piston outer shell is a cylindrical structure with a convex bottom surface;

[0044] The second piston is designed as a hollow structure. The second piston includes 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 by threads. The second piston outer shell is a cylindrical structure with a protruding bottom surface.

[0045] In another preferred example, the first piston outer shell and the first piston top cover are fixed by a first piston fastener.

[0046] In another preferred example, the first piston outer shell is a cylindrical structure with a bottom surface.

[0047] In another preferred example, the second piston outer shell is a cylindrical structure with a bottom surface.

[0048] In another preferred example, the first piston outer shell and the second piston outer shell are close to the discharge leaf spring and arranged opposite to each other.

[0049] In another preferred example, the first piston is made of aluminum alloy material, and the second piston is made of engineering plastic.

[0050] In another preferred embodiment, the outer surface of the first piston is sprayed with a wear-resistant lubricating coating, preferably, sprayed with a Teflon coating.

[0051] In another preferred example, the first cylinder is made of aluminum alloy material, and the second piston is made of engineering plastic.

[0052] In another preferred embodiment, the inner cylinder wall surface of the first cylinder is polished and hard-oxidized.

[0053] In another preferred example, the device also includes a vibration reduction assembly, which is located above the ejector structure and the power piston structure. The vibration reduction assembly includes a power vibration reduction mechanism and a damping vibration reduction mechanism. The power vibration reduction mechanism is used to eliminate the vibration of the fundamental frequency of the refrigerator, and the damping vibration reduction mechanism is used to weaken high-frequency vibration; the damping vibration reduction mechanism is located above the power vibration reduction mechanism.

[0054] In another preferred embodiment, the power vibration reduction mechanism includes multiple groups of power vibration reduction leaf springs, counterweights, and large power vibration reduction screws, and the power vibration reduction leaf springs and the counterweights are fixed together by the large power vibration reduction screws;

[0055] The damping vibration reduction mechanism comprises a damping filler, a damping disk, a gasket, a damping vibration reduction leaf spring, and a large damping vibration reduction screw which are sequentially arranged in the axial direction, and the damping vibration reduction leaf spring, the gasket, and the damping disk are connected and fixed by the large damping vibration reduction screw.

[0056] In another preferred example, the device also includes a shell assembly and a cold finger assembly arranged at the lower end of the shell assembly; the vibration damping 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 includes 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 connected in sequence; and a hot end heat dissipation filler, a heat regenerator, a cold end heat dissipation filler, a hot end limit steel ring, a heat regenerator limit ring, and a cold end limit steel ring which are arranged in sequence along the axial direction.

[0057] In another preferred embodiment, the hot end heat dissipation filler, the regenerator, and the cold end heat dissipation filler are arranged between the second cylinder and the hot end heat dissipation copper ring, the regenerator shell, and the cold end heat dissipation copper ring;

[0058] The hot end limiting steel ring, the regenerator limiting ring, and the cold end limiting steel ring are used to fix the hot end heat dissipation filler, the regenerator, and the cold end heat dissipation filler respectively.

[0059] In another preferred example, it further includes a linear motor assembly, which is located above the cylinder base and includes an outer magnetic yoke, a permanent magnet mover, an inner magnetic yoke, and a coil.

[0060] In another preferred example, the permanent magnet mover includes a permanent magnet, a permanent magnet lower support ring, a permanent magnet upper support ring, and a transmission connecting plate.

[0061] In another preferred example, an outer yoke upper support ring is provided at the upper end of the outer yoke, and an outer yoke lower support ring is provided at the lower end. 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.

[0062] In another preferred example, the permanent magnet mover is fixed together with the power bearing by a tightening nut, the power leaf spring is arranged on the support ring on the outer magnetic yoke, and the power leaf spring and the support ring on the outer magnetic yoke are fastened together by a third screw, and the inner magnetic yoke is fixed on the cylinder base.

[0063] In another preferred example, the shell assembly includes an annular shell and a shell end cover, the lower end surface of the annular shell is fixedly connected to the cold finger base, and the upper end surface of the annular shell is fixedly connected to the shell end cover.

[0064] In another preferred example, the housing assembly further includes a wiring terminal and an air-filled copper tube, wherein the wiring terminal is used to connect the lead wire of the coil, the wiring terminal is arranged on one side of the annular housing, and the air-filled copper tube is arranged on the other side of the annular housing.

[0065] The second aspect of the present application provides an integral free piston Stirling refrigerator device, comprising a vibration reduction assembly, wherein the vibration reduction assembly is located above the displacer structure and the power piston structure, the vibration reduction assembly comprises a power vibration reduction mechanism and a damping vibration reduction mechanism, the power vibration reduction mechanism is used to eliminate the vibration of the refrigerator fundamental frequency, and the damping vibration reduction mechanism is used to reduce the high frequency vibration; the damping vibration reduction mechanism is located above the power vibration reduction mechanism;

[0066] The power vibration reduction mechanism comprises a plurality of groups of power vibration reduction leaf springs, a counterweight block, and a large power vibration reduction screw, and the power vibration reduction leaf springs and the counterweight block are fixed together by the large power vibration reduction screw;

[0067] The damping vibration reduction mechanism comprises a damping filler, a damping disk, a gasket, a damping vibration reduction leaf spring, and a large damping vibration reduction screw which are sequentially arranged in the axial direction, and the damping vibration reduction leaf spring, the gasket, and the damping disk are connected and fixed by the large damping vibration reduction screw.

[0068] In another preferred embodiment, it further comprises a displacer structure and a power piston structure, wherein the power piston structure comprises a power leaf spring, a power bearing and a power piston sequentially arranged in the axial direction, wherein the power leaf spring is connected to the power bearing;

[0069] The ejector structure comprises a first piston, a discharge plate spring, and a second piston which are sequentially arranged in the axial direction.

[0070] wherein the discharge plate spring is connected to 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 the gas pressure difference, the discharge plate spring radially supports the first piston and the second piston and provides axial stiffness for the first piston and the second piston;

[0071] During the refrigeration process, high-pressure gas flows back and forth in the expansion chamber of the second piston at one end away from the discharge leaf spring and the compression chamber of the first piston at one end away from the discharge leaf spring. The gas in the expansion chamber does positive work on the discharger structure, thereby providing refrigeration.

[0072] In another preferred example, it also includes a shell assembly and a cold finger assembly arranged at the lower end of the shell assembly; the vibration damping 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 includes 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 that are coaxially connected in sequence; and a hot end heat dissipation filler, a heat regenerator, a cold end heat dissipation filler, a hot end limit steel ring, a heat regenerator limit ring, and a cold end limit steel ring that are arranged in sequence along the axial direction.

[0073] In another preferred example, it further includes a linear motor assembly, which is located above the cylinder base and includes an outer magnetic yoke, a permanent magnet mover, an inner magnetic yoke, and a coil.

[0074] In another preferred example, the shell assembly includes an annular shell and a shell end cover, the lower end surface of the annular shell is fixedly connected to the cold finger base, and the upper end surface of the annular shell is fixedly connected to the shell end cover.

[0075] In another preferred example, the first piston includes a cylindrical structure with a protruding bottom surface, the second piston includes a cylindrical structure with a protruding bottom surface, the first piston includes a first protruding bottom surface protruding toward the discharge plate spring, and the second piston includes a second protruding bottom surface protruding toward the discharge plate spring. In another preferred example, the ejector structure further includes a first fastener, the first protruding bottom surface is provided with a first protruding portion, the second protruding bottom surface is provided with a second protruding portion, the first fastener passes through the discharge plate spring and is connected to the first protruding portion and the second protruding portion, so that the discharge plate spring is fixedly connected to the first piston and the second piston.

[0076] In another preferred example, the ejector structure further includes a first cylinder and a second cylinder, and both ends of the ejector leaf spring are fixedly connected to the first cylinder or the second cylinder, thereby realizing reciprocating motion of the first piston in the first cylinder and reciprocating motion of the second piston in the second cylinder.

[0077] In another preferred embodiment, the power piston is designed as a hollow structure, and the power piston includes a power piston housing and a power piston end cover.

[0078] The first piston is designed as a hollow structure, comprising a first piston outer shell and a first piston top cover, the first piston outer shell and the first piston top cover are sealed by a first piston seal, and the first piston outer shell is a cylindrical structure with a convex bottom surface;

[0079] The second piston is designed as a hollow structure. The second piston includes 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 by threads. The second piston outer shell is a cylindrical structure with a protruding bottom surface.

[0080] It should be understood that within the scope of the present invention, the above-mentioned technical features of the present invention and the technical features specifically described below (such as embodiments) can be combined with each other to form a new or preferred technical solution. Due to space limitations, they will not be described one by one here. BRIEF DESCRIPTION OF THE DRAWINGS

[0081] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the prior art descriptions are briefly introduced below. It should be understood that the drawings described below are only some implementation examples of the present invention, and ordinary technicians in this field can also obtain other implementation examples based on these drawings without paying creative work.

[0082] Figure 1 is a schematic diagram of an integral free piston Stirling refrigerator device according to an embodiment of the present application;

[0083] Figure 2 is a schematic diagram of the structure of an ejector of a free piston Stirling refrigerator device according to an embodiment of the present application;

[0084] Figure 3 is a schematic cross-sectional structural diagram of an ejector structure of a free piston Stirling refrigerator device according to an embodiment of the present application;

[0085] Figure 4 is a schematic structural diagram of an ejector plate spring of an ejector structure according to an embodiment of the present application;

[0086] Figure 5It is a schematic diagram of the structure of a vibration reduction assembly according to an embodiment of the present application.

[0087] In the accompanying drawings, the markings are as follows:

[0088] 1-first piston; 10-first protruding bottom surface; 101-first protruding portion; 11-first piston outer shell; 12-first piston top cover; 13-first piston sealing member; 14-first piston fastener;

[0089] 2-second piston; 20-second protruding bottom surface; 201-second protruding portion; 21-second piston outer shell; 22-second piston top cover;

[0090] 3-discharge leaf spring; 31-first fastener; 32-second fastener;

[0091] 40-cylinder base; 41-first cylinder; 42-second cylinder; 43-cylinder seal; 421-connecting section; 422-accommodating section; 4221-groove;

[0092] 51-power leaf spring; 52-power bearing; 53-power piston housing; 54-power piston end cover; 55-fastening sheet;

[0093] 61-power damping leaf spring; 62-weight block; 63-power damping large screw; 64-first welding ring; 65-first screw;

[0094] 71-damping filler; 72-damping plate; 73-washer ring; 74-damping vibration reduction leaf spring; 75-damping vibration reduction large screw; 76-second welding ring; 77-second screw;

[0095] 81-cold finger base; 82-hot end heat dissipation copper ring; 83-regenerator shell; 84-cold end heat dissipation copper ring; 85-cold finger end cover; 86-hot end heat dissipation filler; 87-regenerator; 88-cold end heat dissipation filler; 89-hot end limit steel ring; 810-regenerator limit ring; 811-cold end limit steel ring;

[0096] 91-outer yoke; 911-upper support ring of outer yoke; 912-lower support ring of outer yoke; 92-inner yoke; 93-coil; 94-permanent magnet; 95-lower support ring of permanent magnet; 96-upper support ring of permanent magnet; 97-transmission connecting plate; 98-fastening nut; 99-third screw;

[0097] 1001- annular housing; 1002- housing end cover; 1003- wiring terminal; 1004- inflatable copper tube;

[0098] L1 - the axial distance between the center point of the first piston and the center point of the discharge leaf spring in the axial direction of the first piston;

[0099] L2 - the axial distance between the center point of the second piston and the center point of the discharge leaf spring in the axial direction of the second piston;

[0100] δ-The air gap height between the outer wall surface of the first piston and the inner wall surface of the first cylinder. DETAILED DESCRIPTION

[0101] Through extensive and in-depth research, the inventors have developed for the first time an integral free-piston Stirling refrigerator device. By arranging a dynamic vibration reduction mechanism and a damping vibration reduction mechanism, the vibration reduction assembly of the present application can not only eliminate the vibration of the refrigerator's fundamental frequency, but also weaken the high-frequency vibration, thereby enhancing the stability of the refrigerator device. At the same time, the device is provided with a unique ejector structure, which abandons the slender connecting rod structure of the ejector plate spring known in the prior art, eliminates the direct interference and wear between the ejector and other components of the refrigerator, greatly reduces friction damping, and takes into account the characteristics of air tightness, low axial heat conduction and low mass, thereby achieving a better cooling effect.

[0102] As used herein, "ejector" and "ejector structure" are used interchangeably.

[0103] As used herein, "housing," "casing," and "housing body" are used interchangeably.

[0104] As used herein, “axial distance” refers to a distance along the axial direction of the first piston or the second piston.

[0105] As used herein, "hot end piston", "hot end discharge piston" and "first piston" refer to the same component;

[0106] As used herein, "cold end piston", "cold end exhaust piston", and "secondary piston" refer to the same component;

[0107] As used herein, "first cylinder" and "hot end cylinder" refer to the same component;

[0108] As used herein, "second cylinder" and "cold end cylinder" refer to the same component;

[0109] It should be noted that in the application documents of this patent, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that the process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "including one" do not exclude the existence of other identical elements in the process, method, article or device including the elements. In the application documents of this patent, 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, which includes two situations: performing the action only according to the element, and performing the action according to the element and other elements. Expressions such as multiple, multiple, and multiple include 2, 2 times, 2 kinds, and more than 2, more than 2 times, and more than 2 kinds.

[0110] In the present invention, all directional indications (such as up, down, left, right, front, back, etc.) are only used to explain the relative position relationship, movement status, etc. between the components in a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0111] Main advantages of the present invention

[0112] (a) The refrigerator device of the present application is provided with a dynamic vibration reduction mechanism and a damping vibration reduction mechanism so that the vibration reduction component of the present application can both eliminate the vibration of the refrigerator fundamental frequency and weaken the high-frequency vibration;

[0113] (b) The combination of the dynamic vibration reduction mechanism and the damping vibration reduction mechanism of the refrigerator device of the present application 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;

[0114] (c) The ejector structure of the present application eliminates the slender connecting rod structure of the ejector plate spring known in the prior art, and by removing redundant parts other than the cylinder that can directly wear against the ejector, the friction damping of the ejector structure is greatly reduced during movement;

[0115] (d) The ejector structure of the present application eliminates direct interference and wear between the ejector piston and other components of the refrigerator, thereby improving the refrigeration efficiency and stability of the refrigerator;

[0116] (e) The ejector structure of the present application solves the problem of the large distance between the ejector leaf spring and the ejector piston in the prior art by arranging the ejector leaf spring between the first piston and the second piston, so that the coaxiality of the entire ejector is easy to control, the installation difficulty is reduced, and the stability is high;

[0117] (f) The ejector structure of the present application is smaller in size, which reduces the weight of the refrigerator and reduces the difficulty of installation.

[0118] In the following description, many technical details are provided to help readers better understand the present application. However, those skilled in the art can understand that the technical solution claimed in the present application can be implemented even without these technical details and various changes and modifications based on the following embodiments.

[0119] The displacer is an important structure of the free piston Stirling refrigerator. The displacer plays the role of phase adjustment of the working fluid flow inside the refrigerator. The Stirling refrigerator is a process of alternating oscillation of the compression piston and the displacer. The high-pressure gas (helium) flows back and forth between the compression chamber, the hot end radiator, the regenerator, the cold end heat exchanger and the expansion chamber. In a cycle of the refrigerator, the gas in the expansion chamber does positive work on the displacer and generates cooling capacity in the expansion chamber. At the same time, the displacer transfers the work done by the gas in the expansion chamber to the compression chamber, which plays the role of recovering acoustic work and improving the refrigeration efficiency of the refrigerator.

[0120] The free piston Stirling refrigerator is a pneumatic refrigerator, that is, the movement of the displacer in the refrigerator is caused by the pressure difference between the compression chamber and the expansion chamber, and no additional force is applied to drive its movement and the phase adjustment of the internal gas. For the free piston Stirling refrigerator, the displacer is directly connected to the displacer leaf spring and is independent of the compression system. The displacer is a "free" piston. The mass of the displacer, the stiffness of the displacer leaf spring and the damping of the displacer movement process play a key role in the phase adjustment function of the displacer.

[0121] The present application provides an ejector structure for a free piston Stirling refrigerator, which adopts a double cylinder-double ejector structure, which can reduce the damping of the ejector movement process, reduce the axial heat conduction from the hot end through the cylinder and the ejector to the cold end (for example, the second piston is made of engineering plastic material with a small thermal conductivity), reduce the cross-flow between the compression chamber and the expansion chamber through the ejector, ensure the stable operation of the ejector, reduce the difficulty of installation, and improve the stability and refrigeration efficiency of the refrigerator.

[0122] Integral free piston Stirling refrigerator device

[0123] See also Figure 1The refrigerator device of the present application includes a housing assembly, a cold finger assembly arranged at the lower end of the housing assembly, a power piston structure, a displacer structure, a vibration reduction assembly, and a linear motor assembly arranged axially in sequence. The vibration reduction assembly, the displacer structure, and the power piston structure are arranged in the housing assembly and the cold finger assembly. The piston assembly (first piston, second piston, and power piston) included in the refrigerator device of the present application slides in the cylinder assembly (first cylinder, second cylinder), and the piston assembly and the cylinder assembly together constitute the displacer structure and the power piston structure of the refrigerator device described in the present application.

[0124] Vibration reduction components

[0125] See also Figure 5 The vibration reduction assembly is located above the displacer structure and the power piston structure. The vibration reduction assembly includes a power vibration reduction mechanism and a damping vibration reduction mechanism. The power vibration reduction mechanism is used to eliminate the vibration of the fundamental frequency of the refrigerator, and the damping vibration reduction mechanism is used to weaken the high-frequency vibration. The damping vibration reduction mechanism is located above the power vibration reduction mechanism.

[0126] The power vibration reduction mechanism includes multiple groups of power vibration reduction leaf springs 61, counterweights 62, and large power vibration reduction screws 63, and the power vibration reduction leaf springs 61 and the counterweights 62 are fixed together by the large power vibration reduction screws 63; the damping vibration reduction mechanism includes a damping filler 71, a damping disk 72, a gasket 73, a damping vibration reduction leaf spring 74, and a large damping vibration reduction screw 75 arranged in sequence along the axial direction, and the damping vibration reduction leaf spring 74, the gasket 73, and the damping disk 72 are connected and fixed by the large damping vibration reduction screws 75.

[0127] The vibration reduction assembly is composed of a power vibration reduction mechanism and a damping vibration reduction mechanism. The power vibration reduction mechanism is used to eliminate the vibration of the refrigerator's fundamental frequency, and the damping vibration reduction mechanism is used to reduce the refrigerator's high-frequency vibration. It has a simple structure and low installation difficulty, and greatly reduces the vibration of the refrigerator. It can be used to work in an environment with high vibration requirements.

[0128] Other Components

[0129] The cold finger assembly includes a cold finger base 81, a hot end heat dissipation copper ring 82, a heat regenerator shell 83, a cold end heat dissipation copper ring 84, and a cold finger end cover 85, which are coaxially connected in sequence; and a hot end heat dissipation filler 86, a heat regenerator 87, a cold end heat dissipation filler 88, and a hot end limiting steel ring 89, a heat regenerator limiting ring 810, and a cold end limiting steel ring 811, which are sequentially arranged along the axial direction.

[0130] The linear motor assembly is located above the cylinder base 40 , and the linear motor assembly includes an outer magnetic yoke 91 , a permanent magnet mover, an inner magnetic yoke 92 , and a coil 93 .

[0131] The housing assembly includes an annular housing 1001 and a housing end cover 1002 . The lower end surface of the annular housing 1001 is fixedly connected to the cold finger base 81 , and the upper end surface of the annular housing 1001 is fixedly connected to the housing end cover 1002 .

[0132] Ejector structure

[0133] See also Figure 2 The displacer structure includes a double cylinder (a first cylinder 41 and a second cylinder 42), a double piston displacer (a first piston 1 and a second piston 2), and a displacer plate spring 3; the displacer plate spring 3 is disposed between the first piston 1 and the second piston 2;

[0134] The first piston 1 and the second piston 2 are connected and fixed to the first piston 1, the second piston 2 and the discharge plate spring 3 by a first fastener 31, so that when the first piston 1 and the second piston 2 reciprocate under the action of the air pressure difference, the discharge plate spring 3 radially supports the first piston 1 and the second piston 2 and provides axial stiffness for the first piston 1 and the second piston 2. During the refrigeration process, the high-pressure gas reciprocates in the expansion chamber of the second piston 2 at one end away from the discharge plate spring 3 and the compression chamber between the first piston 1 and the power piston, and the gas in the expansion chamber reciprocates in the expansion chamber of the second piston 2 at one end away from the discharge plate spring 3 and the compression chamber of the first piston 1 at one end away from the discharge plate spring 3. The gas in the expansion chamber does positive work on the discharger structure, thereby providing refrigeration.

[0135] In one embodiment, the first fastener 31 is a stud of appropriate size. In one embodiment, the discharge leaf spring 3 is composed of a double discharge leaf spring. In one embodiment, the central axes of the first piston 1 and the second piston 2 are on the same straight line. In one embodiment, the central axes of the first piston 1 and the second piston 2 pass through the center point of the discharge leaf spring. In one embodiment, the discharge leaf spring 3 is fixedly connected to the first piston 1 and the second piston 2 through the first fastener 31. In one embodiment, the first piston 1, the second piston 2 and the discharge leaf spring 3 are coaxially installed.

[0136] Discharge leaf spring

[0137] See also Figure 3 and Figure 4 ,in Figure 3 A schematic cross-sectional view of the ejector structure of a free piston Stirling refrigerator device is shown; Figure 4 A schematic diagram showing the structure of the ejector plate spring of the ejector structure;

[0138] Both ends of the discharge leaf spring 3 are fixedly connected to the first cylinder 41 or the second cylinder 42 , so that the first piston 1 can reciprocate in the first cylinder 41 and the second piston 2 can reciprocate in the second cylinder 42 .

[0139] In one embodiment, both ends of the discharge leaf spring 9 (ends away from the center of the discharge leaf spring) are connected and fixed to the end surface of the first cylinder 41 (end surface facing the second cylinder 42) by a second fastener 32. In one embodiment, the second fastener 32 is a second hexagon socket screw. In one embodiment, the edge (end) of the discharge leaf spring 3 away from the center is connected to the first cylinder 41 by a screw.

[0140] First cylinder and second cylinder

[0141] See also Figure 2-Figure 4 The ejector structure of the present application adopts a double cylinder form, which includes a first cylinder 41 and a second cylinder 42. The first piston 1 reciprocates in the first cylinder 41, and the second piston 2 reciprocates in the second cylinder 42;

[0142] The second cylinder 42 includes a connecting section 421 and a accommodating section 422. In the radial direction of the cylinder, the connecting section 421 is located on the outside of the first cylinder 41. In other words, the first cylinder 41 is inserted into the connecting section 421 of the second cylinder 42, wherein the gap between the connecting section 421 and the first cylinder 41 is sealed.

[0143] In one embodiment, a plurality of grooves 4221 are provided on the inner wall of the accommodating section 422 to reduce the amount of gas cross-talk between the compression chamber and the expansion chamber through the gap, which has a positive effect on the sealing effect.

[0144] In one embodiment, the first cylinder 41 and the second cylinder 42 are gap-sealed by a cylinder seal 43. In one embodiment, the first cylinder 41 and the second cylinder 42 are gap-sealed by an O-ring and the interface between the first cylinder 41 and the second cylinder 42 is glued and fixed. In one embodiment, the interface between the connecting section 421 of the second cylinder 42 and the first cylinder 41 is glued, so as to fix the second cylinder 42 and the first cylinder 41.

[0145] For the first cylinder, the power piston (not shown) and the first piston reciprocate and vibrate inside the cylinder to seal the gas. The air gap between the first cylinder and the first piston (hot end ejector piston) is very small to ensure good air tightness.

[0146] The first piston and the second piston

[0147] See also Figure 2-Figure 4The first piston 1 includes a cylindrical structure with a protruding bottom surface, and the second piston 2 includes a cylindrical structure with a protruding bottom surface. The first piston 1 includes a first protruding bottom surface 10 protruding toward the discharge leaf spring 3, and the second piston 2 includes a second protruding bottom surface 20 protruding toward the discharge leaf spring 3, wherein the first protruding bottom surface 10 and / or the second protruding bottom surface 20 are arranged to avoid the end or edge of the discharge leaf spring 3, away from the center, from colliding with the first piston 1 and / or the second piston 2 during the movement of the piston.

[0148] In one embodiment, the ejector structure further includes a first fastener 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, the first fastener 31 passes through the ejection leaf spring 3 and is connected with the first protruding portion 101 and the second protruding portion 201, so that the ejection leaf spring 3 is fixedly connected with the first piston 1 and the second piston 2. In one embodiment, the first protruding portion 101 is located at the center of the first protruding bottom surface 10, and the first protruding portion 101 is a cylindrical structure extending toward the ejection leaf spring 3. In one embodiment, the second protruding portion 201 is located at the center of the second protruding bottom surface 20, and the second protruding portion 201 is a cylindrical structure extending toward the ejection leaf spring 3. In one embodiment, the first fastener 31 is a stud.

[0149] In one embodiment, the first protrusion 101 is a cylindrical structure with an internal thread, and the second protrusion 201 is a cylindrical structure with an internal thread. The internal thread cooperates with the external thread of the stud to complete the connection. Preferably, an appropriate amount of thread glue is applied when the first protrusion 101 and the second protrusion 201 are connected to the stud thread.

[0150] In one embodiment, when the discharge leaf spring 3 is connected to the first protrusion 101 and the second protrusion 201 by the first fastener 31, the end surface of the first protrusion 101 is in contact with one surface of the discharge leaf spring 3, and the end surface of the second protrusion 201 is in contact with the other surface of the discharge leaf spring.

[0151] In one embodiment, the axial distance between the first protruding bottom surface 10 of the first piston 1 and the discharge leaf spring 3 should be greater than the maximum amplitude of the discharger structure, and the axial distance between the second protruding bottom surface 20 of the second piston 2 and the discharge leaf spring 3 should also be greater than the maximum amplitude of the discharger structure.

[0152] In order to achieve better air tightness, the first piston 1 should maintain a small gap 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 of the cylinder. In order to prevent the ejector from contacting the wall and causing a substantial increase in friction, it is assumed that the axial distance between the geometric center of the first piston and the center of the ejection leaf spring (or the axial distance between the center point of the first piston and the center point of the ejection leaf spring along the axial direction of the first piston) L1, the axial distance between the center point of the second piston and the center of the ejection leaf spring along the axial direction of the second piston (the second piston outer shell 21 and the second piston top cover 22) L2, the weight of the first piston 1 m1, the weight of the second piston 2 m2, the radial stiffness of the ejection leaf spring 3, and the air gap δ between the first piston and the cylinder should maintain a certain relationship,

[0153] The positional relationship among the first piston 1, the second piston 2 and the discharge plate spring 3 can satisfy the following formula:

[0154]

[0155]

[0156] 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 center of the hot end discharge piston and the center of the discharge leaf spring, L2 is the axial distance between the center of the cold end discharge piston and the center of the discharge leaf spring, g is the acceleration of gravity, k is the radial stiffness of the discharge leaf spring 9, and δ is the air gap height between the wall of the hot end discharge piston and the inner wall of the hot end cylinder. Figure 3 , where L1, L2, and δ are shown schematically.

[0157] (a) First piston

[0158] In order to reduce the mass of the displacer and make it lighter, the first piston 1 adopts a hollow structure, and the first piston 1 includes 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 seal 13, and the first piston outer shell 11 and the first piston top cover 12 are connected and fixed by a first piston fastener 14. In one embodiment, the first piston seal 13 is an O-ring. In one embodiment, the first piston fastener 14 is a hexagon socket screw. Preferably, the first piston outer shell 11 is a cylindrical structure with a bottom surface.

[0159] In one embodiment, the first piston housing 11, the first piston top cover 12, an O-ring and a plurality of screws constitute a first piston assembly. The first piston housing 11 and the first piston top cover 12 are sealed by an O-ring to prevent the loss of compression work caused by the gas in the compression chamber entering and exiting the first piston assembly. The first piston housing 11 and the first piston top cover 12 are fastened by eight screws.

[0160] In order to avoid direct collision between the first piston and the deformed discharge plate spring during the movement, the first piston housing has a certain slope on the side close to the cold end (second piston) or the discharge plate spring 3, and the size of the slope is determined according to the maximum amplitude of the discharger assembly. In other words, the first piston housing includes a first protruding bottom surface 10 facing the discharge plate spring 3, so that the bottom surface of the first piston housing has a slope, and the maximum axial distance between the first protruding bottom surface 10 of the first piston 1 and the discharge plate spring 3 should be greater than the maximum amplitude of the discharger structure; at the same time, the first piston housing (hot end piston housing) of the discharger has a cylindrical protrusion (first protrusion 101) on the side close to the expansion chamber (or close to the discharge plate spring), and the center of the protruding cylinder is processed with an internal thread to facilitate connection with the discharge plate spring 3 and the second piston 2.

[0161] (b) Second piston

[0162] In order to reduce the mass of the ejector and make it lighter, the second piston 2 adopts a hollow structure. Preferably, in order to reduce the internal empty volume and control the mass, the second piston is filled with a rollable lightweight material. The second piston 2 includes 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 by internal and external threads. Preferably, the first piston outer shell 11 and the second piston outer shell 21 are arranged relatively close to the ejection plate spring 3. Preferably, the second piston outer shell is a cylindrical structure with a bottom surface.

[0163] Similarly, to prevent the second piston from colliding with the discharge leaf spring during movement, the second piston outer shell has a certain slope on the side close to the discharge leaf spring, and the size of the slope is determined according to the maximum amplitude of the discharger assembly, that is, the second piston outer shell includes a second protruding bottom surface 20 facing the discharge leaf spring 3, so that the bottom surface of the second piston outer shell has a slope, and the maximum axial distance between the second protruding bottom surface 20 of the second piston 2 and the discharge leaf spring 3 should be greater than the maximum amplitude of the discharger structure. The second piston outer shell will have a boss (second protruding portion 201) close to the discharge leaf spring, and the center of the boss has an internal threaded hole of a certain depth.

[0164] In one embodiment, a stud passes through the inner thread of the protrusion (first protrusion 101) or boss (second protrusion 201) of the first and second piston outer shells, and connects the discharge leaf spring to the first and second piston outer shells and fixes them with glue on the surface of the screw.

[0165] Power piston structure

[0166] The power piston structure includes a power leaf spring 51, a power bearing 52 and a power piston arranged in sequence along the axial direction. The power piston is placed in the first cylinder 41 and slides back and forth. The power piston is designed as a hollow structure. The power piston includes a power piston housing 53 and a power piston end cover 54. The power piston is arranged opposite to the first piston 1. During the refrigeration process, the compression chamber of the gas is between the power piston and the first piston 1.

[0167] The power leaf spring 51 is fixedly connected to the power bearing 52, and the power bearing 52 is fastened to the permanent magnet mover of the linear motor assembly to form a whole.

[0168] Materials of each component

[0169] The prior art ejector structure is composed of a single piston. The ejector runs through the compression chamber at the hot end and the expansion chamber at the cold end. The ejector structure is generally made of aluminum alloy, stainless steel or polymer (engineering plastic). For the ejector structure made of metal, the thermal deformation is small, the strength is high, the processing accuracy is high, and the thermal conductivity is high. The gap between the cylinder and the ejector can be designed to be very small, the air tightness is good, and the shuttle loss and pumping loss are small; but the disadvantage is that the axial heat conduction from the compression chamber to the expansion chamber is large, and the mass of the ejector is also large. For polymer materials, the strength is generally low, the processing accuracy is low, the thermal deformation is large, and the thermal conductivity is small; its advantage is that the axial heat conduction from the compression chamber to the expansion chamber through the ejector body is small and the mass is light; the disadvantage is that a certain gap must be maintained between the ejector and the cylinder to prevent the direct friction between the ejector and the cylinder due to temperature changes, resulting in a huge increase in the damping of the ejector.

[0170] The various problems caused by the use of a single material for the ejector structure (as mentioned above) are solved by minimizing the axial heat conduction loss as much as possible while ensuring the airtightness between the compression chamber and the expansion chamber (reducing shuttle loss and pumping loss) to improve the efficient cooling effect of the refrigerator.

[0171] Therefore, in order to reduce the transfer of heat from the hot end to the cold end of the refrigerator through the cylinder, and at the same time to maintain a small gap between the piston and the cylinder, in the technical solution of the present application, the cylinder structure and the ejector structure are both made of a mixture of two materials, wherein the first cylinder is made of metal material, such as aluminum alloy, stainless steel, titanium alloy, etc., and the second cylinder is made of a high molecular polymer (engineering plastic) with low thermal conductivity and high strength, and the first cylinder and the second cylinder are connected by an O-ring, and glue is used to bond the two.

[0172] Preferably, the first piston 1 is made of aluminum alloy material with high strength and low density, and the hot end discharge piston surface is evenly sprayed with wear-resistant and lubricating coatings such as Teflon. The second piston 2 is made of engineering plastics with low thermal conductivity, low temperature resistance and low thermal expansion coefficient.

[0173] Preferably, the first cylinder 41 is made of an aluminum alloy material with high thermal conductivity and high strength, wherein the inner cylinder wall surface of the first cylinder 41 is polished and hard-oxidized.

[0174] The second cylinder 42 is made of engineering plastics with low thermal conductivity, high strength and low thermal expansion coefficient. The inner wall surface of the accommodating section 422 of the second cylinder 42 adopts a sealing structure with multiple grooves 4221.

[0175] To make the purpose, technical solution and advantages of the present invention clearer, the embodiments of the present invention will be further described in detail below in conjunction with the accompanying drawings. It should be understood that these are only some examples that the present invention may take for the reader, but are not intended to limit the scope of the present invention.

[0176] Example

[0177] Integral free piston Stirling refrigerator device

[0178] See also Figure 1 The present embodiment provides an integrated free piston Stirling refrigerator device, which is composed of a cold finger assembly, a linear motor assembly, a cylinder assembly, a piston assembly, a housing assembly, and a vibration reduction assembly.

[0179] The piston assembly consists of a power piston structure and a discharge piston structure (which will be described in detail below). The discharge piston structure consists of a first piston 1 (hot end discharge piston) and a second piston 2 (cold end discharge piston). The hot end discharge piston consists of a hot end discharge piston housing (first piston outer housing 11) and a hot end discharge piston end cover (first piston top cover 12), and the cold end discharge piston (second piston 2) consists of a cold end discharge piston housing (second piston outer housing 21) and a cold end discharge piston end cover (second piston top cover 22). Both the cold and hot end discharge pistons are designed as hollow structures, and have cylindrical protrusions at the ends, and the cylindrical protrusions are processed with internal threads. The cold and hot end discharge pistons are installed and fastened on both sides of the discharge plate spring 3 by studs (first fasteners 31). The cold end discharge piston is made of engineering plastic materials with light weight, low thermal conductivity and low thermal expansion coefficient; the hot end discharge piston is made of aluminum alloy materials with light weight, high strength and hardness, and the surface is evenly sprayed with Teflon coating. The hot end discharge piston slides back and forth in the first cylinder 41 (hot end cylinder), and the cold end discharge piston slides back and forth in the second cylinder 42 (cold end cylinder). The power piston structure consists of a power leaf spring 51, a power bearing 52, and a power piston. The power piston is designed as a hollow structure, and the power piston consists of a power piston housing 53 and a power piston end cover 54. The power bearing 52 and the power piston are both made of lightweight, high-strength aluminum alloy material. The power piston is fastened to the power bearing 52 by screws, and the power piston is placed in the hot end cylinder 41 and slides back and forth.

[0180] The vibration reduction assembly is composed of a power vibration reduction mechanism and a damping vibration reduction mechanism. The power vibration reduction mechanism is used to eliminate the vibration of the fundamental frequency of the refrigerator, and the damping vibration reduction mechanism is used to reduce the high-frequency vibration. The power vibration reduction mechanism is composed of a power vibration reduction plate spring 61, a counterweight block 62, and a large power vibration reduction screw 63. An internal threaded through hole is drilled in the center of the counterweight block 62, and the counterweight block 62 and a plurality of power vibration reduction plate springs 61 are fastened together by the large power vibration reduction screw 63. A first welding ring 64 is welded on the inner side of the shell, and a plurality of through holes are drilled on the first welding ring 64. A plurality of through holes are also drilled on the outer ring of the power vibration reduction plate spring 61, and the power vibration reduction plate spring 61 is mounted on the first welding ring 64 by a first screw 65 and a nut. The damping vibration reduction mechanism includes a damping filler 71, a damping disc 72, a gasket 73, a damping vibration reduction plate spring 74, and a large damping vibration reduction screw 75 from top to bottom in the axial direction. A second welding ring 76 is welded on the inner side of the shell. The damping filler 71 is composed of axially stacked copper wire meshes, and is bonded and fixed to the housing end cover 1002 by thermally conductive silicone. A threaded hole is drilled in the center of the damping plate 72, and the damping plate spring 74, the gasket 73, and the damping plate 72 are connected and fixed by the large damping screw 75, and the damping plate spring 74 is fixed to the second welding ring 76 by the second screw 77 and the nut.

[0181] The cold finger assembly consists of a cold finger end cap 85, a cold end heat dissipation copper ring 84, a regenerator shell 83, a hot end heat dissipation copper ring 82, a cold finger base 81, a cold end heat dissipation filler 88, a regenerator 87, a hot end heat dissipation filler 86, a cold end limit steel ring 811, a regenerator limit ring 810, and a hot end limit steel ring 89. The cold finger end cap 85, the cold end heat dissipation copper ring 84, the regenerator shell 83, the hot end heat dissipation copper ring 82, and the cold finger base 81 are coaxially installed and welded together by vacuum brazing, and the coaxiality is controlled within 0.005 mm. The hot-end heat dissipation filler 86 and the cold-end heat dissipation filler 88 adopt a folded copper sheet structure and are pressed into the corresponding positions on the inner side of the cold finger by a hydraulic press; the heat regenerator 87 adopts a wound polymer film or stainless steel wire mesh filler; the cold-end limiting steel ring 811, the heat regenerator limiting ring 810, and the hot-end limiting steel ring 89 are pressed into the corresponding positions in sequence to fix the cold- and hot-end heat dissipation fillers 88, 86 and the heat regenerator 87.

[0182] The cylinder assembly consists of a first cylinder 41 (hot end cylinder), a second cylinder 42 (cold end cylinder), and a cylinder base 40. The hot end cylinder 41 is made of an aluminum alloy material with good thermal conductivity, and the cold end cylinder 42 is made of engineering plastic material with light weight, low thermal conductivity, and low thermal expansion coefficient. The hot end cylinder 41 and the cold end cylinder 42 are coaxially assembled and fixed by adhesive. The inner surface of the cylinder base 40 is processed with a plurality of annular grooves, and the hot end cylinder 41 is coaxially inserted into the inside of the cylinder base, and the hot end cylinder 41 and the cylinder base 40 are sealed by an O-ring. The bottom surface of the cylinder base 40 is drilled with a plurality of through holes, and the upper end surface of the hot end cylinder 41 is processed with a plurality of screw holes, and the cylinder base 40 is connected and fixed with the hot end cylinder 41 by screws. The cylinder base 40 is connected and fastened to the cold finger bottom 81 by screws. A hollow groove is opened in the center of the hot end cylinder 41 to allow the compression chamber to form a passage with the expansion chamber through the hot end heat dissipation filler 86, the heat regenerator 87, and the cold end heat dissipation filler 88.

[0183] The linear motor assembly includes an outer yoke 91, a permanent magnet mover, an inner 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 connection plate 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 through stud nuts; the annular permanent magnet 94, the permanent magnet lower support ring 95, the permanent magnet upper support ring 96, and the transmission connection plate 97 are fastened as a whole through stud nuts and the radiation ring is magnetized as a whole, and the permanent magnet mover is fastened to the power bearing 52 through the fastening nut 98 to form a whole, and the power leaf spring 51 is placed on the outer yoke upper support ring 911 and fastened through the third screw 99. There is a circular hole in the center of the power leaf spring 51, and there are several internal threads on the tail end face of the power bearing 52. The end of the power bearing 52 passes through the circular hole so that the bottom surface of the power leaf spring 51 fits with the upper end face of the fastening nut 98, and the center of the power leaf spring 51 and the power bearing 52 are fastened by the fastening sheet 55 and the screw. The coil 93 is evenly and tightly wound around the hollow position of the inner magnetic yoke 92 to form a whole. The inner magnetic yoke 92 has a through-hole structure in the axial direction, and the inner magnetic yoke 92 is fixed to the cylinder base 40 by a stud nut. The center position deviation of the permanent magnet 94, the outer magnetic yoke 91, and the inner magnetic yoke 92 is controlled within 0.1mm.

[0184] The housing assembly includes an annular housing 1001, a housing end cover 1002, a terminal 1003, and an inflatable 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 cover 1002 by argon arc welding. A through hole is processed on the side of the housing 1001, and the terminal 1003 is welded to the housing 1001 by energy storage welding, and the two leads of the coil 93 are connected to the inner side of the refrigerator terminal 1003. There is a circular hole on the other side of the housing 1001, and the inflatable 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 at high temperature for a certain period of time before installation.

[0185] Ejector structure

[0186] This embodiment also provides an ejector structure for a free piston Stirling refrigerator device, which adopts a double cylinder-double piston structure, such as Figure 2-Figure 4 The device includes: a first piston 1, a second piston 2, a discharge leaf spring 3, a first cylinder 41, and a second cylinder 42.

[0187] The first piston 1, the second piston 2, and the discharge plate spring 3 are arranged in the axial direction, and the discharge plate spring 3 is arranged between the first piston 1 and the second piston 2. The discharge plate spring 3 is connected to the first piston 1 and the second piston 2 through a first fastener 31, so that when the first piston 1 and the second piston 2 reciprocate under the action of the gas pressure difference, the discharge plate spring 3 radially supports the first piston 1 and the second piston 2 and provides axial stiffness for the first piston 1 and the second piston 2;

[0188] Specifically, see Figure 3 The first piston 1 includes 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 O-ring (i.e., an example of the first piston seal 13), and the two are fixed by a first hexagon socket screw (i.e., an example of the first piston fastener 14). The first piston outer shell 11 is a cylindrical structure with a protruding bottom surface. The first piston 1 includes a first protruding bottom surface 10 protruding toward the discharge leaf spring 3. The first protruding bottom surface 10 is provided with a cylindrical protrusion 101 (i.e., the first protruding portion 101) facing the discharge leaf spring 3, and the center of the protruding cylinder is processed with an internal thread;

[0189] The second piston 2 includes a second piston outer shell 21 and a second piston top cover 22, which are fixedly connected and sealed by internal and external threads. The second piston outer shell 21 is a cylindrical structure with a protruding bottom surface, and the second piston outer shell 21 includes a second protruding bottom surface 20 protruding toward the discharge leaf spring 3, and the second protruding bottom surface 20 is provided with a boss (i.e., a second protruding portion 201) facing the discharge leaf 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 leaf spring 3 are connected and fixed by a stud of a suitable size, and the stud passes through the protrusion (first protruding portion 101) of the first protruding bottom surface, the discharge leaf spring 3, and the boss 201 (i.e., the second protruding portion 201) of the second protruding bottom surface 20. Among them, the installation coaxiality of the first piston 1, the second piston 2 and the discharge leaf spring 3 is controlled within 0.005mm.

[0190] The discharge leaf spring 3 is connected and fixed to the upper end surface of the first cylinder 41 by a second hexagon socket screw (ie, an example of the second fastener 32 ), and the coaxiality of the discharge leaf spring 3 and the first cylinder 41 is controlled within 0.005 mm.

[0191] The first cylinder 41 and the second cylinder 42 are gap-sealed by a second O-ring (ie, an example of a cylinder seal 43) and the interface between the two is glued and fixed. The installation coaxiality of the first cylinder 41 and the second cylinder 42 is controlled within 0.005 mm.

[0192] In this embodiment, the first piston 1 is made of aluminum alloy material with high strength and low density, and the hot end discharge piston surface is evenly sprayed with a wear-resistant and lubricating coating such as Teflon. The second piston 2 is made of engineering plastics with low thermal conductivity, low temperature resistance, and low thermal expansion coefficient. The first cylinder 1 is made of aluminum alloy material with high thermal conductivity and high strength, and the inner cylinder wall of the hot end cylinder is polished and hard-oxidized. The second cylinder 42 is made of engineering plastics with low thermal conductivity, high strength, and low thermal expansion coefficient, and the inner wall of the cylinder adopts a multi-groove sealing structure.

[0193] Discharger structure installation steps:

[0194] (1) Put an O-ring of appropriate size on the boss of the first piston top cover, and fix the first piston top cover to the first piston outer shell with 8 screws.

[0195] (2) The lightweight material is evenly filled on the second piston outer shell, and then the second piston top cover is fixed to the second piston thread.

[0196] (3) A stud of appropriate size and length is inserted through the circular hole in the center of the discharge leaf spring 3, and the first piston and the second piston are connected by threads. The convex end surface of the second piston outer shell (i.e., the end surface of the first protrusion 101 of the first protruding bottom surface 10) and the convex end surface of the first piston outer shell (i.e., the end surface of the second protrusion 201 of the first protruding bottom surface 10) are flush with the two surfaces of the discharge leaf spring, and a proper amount of thread glue is applied during the threaded connection. It should be noted that during the installation process, the coaxiality of the discharge leaf spring, the first piston (the first piston outer shell 11 and the first piston top cover 12) and the second piston (the second piston outer shell 21 and the second piston top cover 22) should be maintained within 0.005mm.

[0197] (4) The discharge leaf spring is coaxially mounted on the end face of the first cylinder by eight screws, and the coaxiality is required to be within 0.005 mm.

[0198] (5) Finally, the first cylinder 41 and the second cylinder 42 are sealed by an O-ring and a proper amount of anaerobic glue is filled in the gap between the two to ensure the fixation of the two. The coaxiality should be controlled within 0.005 mm during the installation process.

[0199] It is worth mentioning that all parts need to be dried in a drying oven at high temperature for a certain period of time before installation.

[0200] The applicant would like to emphasize that the ejector structure of this embodiment abandons the practice of using an ejector base placed inside the compression chamber and a ejector plate spring arranged inside the ejector, and removes unnecessary parts other than the cylinder that can directly wear against the ejector, thereby greatly reducing damping while ensuring excellent air tightness between the ejector and the cylinder (small shuttle loss and pump air loss), not increasing the empty volume of the compression chamber or the expansion chamber, small axial heat conduction of the ejector, not affecting the maximum power of the refrigerator, simplifying the structure of the refrigerator, and reducing the difficulty of installation while ensuring safe and reliable operation of the refrigerator.

[0201] A large number of technical features are recorded in the specification of this application, which are distributed in various technical solutions. If all possible combinations of technical features of this application (i.e., technical solutions) are to be listed, the specification will be too long. In order to avoid this problem, the various technical features disclosed in the above-mentioned invention content of this application, the various technical features disclosed in the various embodiments and examples below, and the various technical features disclosed in the accompanying drawings can be freely combined with each other to form various new technical solutions (these technical solutions are all deemed to have been recorded in this specification), unless the combination of such technical features is technically infeasible. For example, in one example, feature A+B+C is disclosed, and in another example, feature A+B+D+E is disclosed, and features C and D are equivalent technical means that play the same role. Technically, only one can be used, and it is impossible to use them at the same time. Feature E can be combined with feature C technically. Then, the solution of A+B+C+D should not be deemed to have been recorded because it is technically infeasible, and the solution of A+B+C+E should be deemed to have been recorded.

[0202] All documents mentioned in this application are considered to be included in the disclosure of this application as a whole, so that they can be used as the basis for modification when necessary. In addition, it should be understood that after reading the above disclosure of this application, those skilled in the art can make various changes or modifications to this application, and these equivalent forms also fall within the scope of protection claimed in this application.

Claims

1. An integral free piston Stirling refrigerator device, characterized in that: include: The ejector structure and the power piston structure, wherein: The power piston structure comprises a power leaf spring (51), a power bearing (52) and a power piston which are sequentially arranged in the axial direction, wherein the power leaf spring (51) is connected to the power bearing (52); The displacer structure comprises a first piston (1), a displacer plate spring (3), and a second piston (2) which are sequentially arranged in the axial direction. The discharge plate spring (3) is connected to the first piston (1) and the second piston (2) through a first fastener (31), so that when the first piston (1) and the second piston (2) reciprocate under the action of a gas 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); During the refrigeration process, high-pressure gas reciprocates in the expansion chamber of the second piston (2) at one end away from the discharge plate spring (3) and the compression chamber between the first piston (1) and the power piston. The gas in the expansion chamber performs positive work on the discharger structure, thereby providing refrigeration. The device also includes a linear motor assembly, which is located above the power piston, and the power leaf spring (51) is arranged above the linear motor assembly.

2. An integral free piston Stirling refrigerator device, characterized in that: include: The ejector structure and the power piston structure, wherein: The power piston structure comprises a power leaf spring (51), a power bearing (52) and a power piston which are sequentially arranged in the axial direction, wherein the power leaf spring (51) is connected to the power bearing (52); The displacer structure comprises a first piston (1), a displacer plate spring (3), and a second piston (2) which are sequentially arranged in the axial direction. The discharge plate spring (3) is connected to the first piston (1) and the second piston (2) through a first fastener (31), so that when the first piston (1) and the second piston (2) reciprocate under the action of a gas 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); During the refrigeration process, high-pressure gas reciprocates in the expansion chamber of the second piston (2) at one end away from the discharge plate spring (3) and the compression chamber between the first piston (1) and the power piston. The gas in the expansion chamber performs positive work on the discharger structure, thereby providing refrigeration. The first piston (1) is a hollow structure, comprising 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) being sealed by a first piston seal (13), the first piston outer shell (11) being a cylindrical structure with a protruding bottom surface; the second piston (2) is a hollow structure, comprising 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) being fixedly connected and sealed by threads, the second piston outer shell (21) being a cylindrical structure with a protruding bottom surface.

3. An integral free piston Stirling refrigerator device, characterized in that: include: The ejector structure and the power piston structure, wherein: The power piston structure comprises a power leaf spring (51), a power bearing (52) and a power piston which are sequentially arranged in the axial direction, wherein the power leaf spring (51) is connected to the power bearing (52); The displacer structure comprises a first piston (1), a displacer plate spring (3), and a second piston (2) which are sequentially arranged in the axial direction. The discharge plate spring (3) is connected to the first piston (1) and the second piston (2) through a first fastener (31), so that when the first piston (1) and the second piston (2) reciprocate under the action of a gas 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); During the refrigeration process, high-pressure gas reciprocates in the expansion chamber of the second piston (2) at one end away from the discharge plate spring (3) and the compression chamber between the first piston (1) and the power piston. The gas in the expansion chamber performs positive work on the discharger structure, thereby providing refrigeration. The first piston (1) comprises a first protruding bottom surface (10) protruding toward the discharge leaf spring (3), and the second piston (2) comprises a second protruding bottom surface (20) protruding toward the discharge leaf spring (3). The discharger structure further comprises a first fastener (31), the first protruding bottom surface (10) is provided with a first protruding portion (101), and the second protruding bottom surface (20) is provided with a second protruding portion (201). The first fastener (31) passes through the discharge leaf spring (3) and is connected to the first protruding portion (101) and the second protruding portion (201), so that the discharge leaf spring (3) is fixedly connected to the first piston (1) and the second piston (2).

4. The refrigerator device according to any one of claims 1 to 3, characterized in that: The device also includes a vibration reduction assembly, which is located above the ejector structure and the power piston structure. The vibration reduction assembly includes a power vibration reduction mechanism and a damping vibration reduction mechanism. The power vibration reduction mechanism is used to eliminate the vibration of the fundamental frequency of the refrigerator, and the damping vibration reduction mechanism is used to weaken high-frequency vibration; the damping vibration reduction mechanism is located above the power vibration reduction mechanism.

5. The refrigerator device according to claim 4, characterized in that: The power vibration reduction mechanism comprises a plurality of groups of power vibration reduction leaf springs (61), a counterweight block (62), and a large power vibration reduction screw (63), and the power vibration reduction leaf springs (61) and the counterweight block (62) are fixed together by the large power vibration reduction screw (63); The damping vibration reduction mechanism comprises a damping filler (71), a damping disk (72), a gasket (73), a damping vibration reduction plate spring (74), and a large damping vibration reduction screw (75) which are sequentially arranged in the axial direction, and the damping vibration reduction plate spring (74), the gasket (73), and the damping disk (72) are connected and fixed by the large damping vibration reduction screw (75).

6. The refrigerator device according to claim 5, characterized in that: The positional relationship between the first piston, the second piston and the discharge plate spring must 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 center point of the first piston and the center point of the discharge leaf spring along the axial direction of the first piston, L2 is the axial distance between the center point of the second piston and the center point of the discharge leaf spring along the axial direction of the second piston, g is the acceleration of gravity, k is the radial stiffness of the discharge leaf spring, and δ is the air gap height between the outer wall surface of the first piston and the inner wall surface of the first cylinder.

7. The refrigerator device according to claim 6, characterized in that: The displacer structure further comprises a first cylinder (41) and a second cylinder (42), and both ends of the displacer plate spring (3) are fixedly connected to the first cylinder (41) or the second cylinder (42), so that the first piston (1) reciprocates in the first cylinder (41), the second piston (2) reciprocates in the second cylinder (42), and the power piston slides in the first cylinder.

8. The refrigerator device according to claim 7, characterized in that: The second cylinder (42) comprises a connecting section (421) and a containing section (422); the connecting section is located outside the first cylinder (41) in the radial direction of the cylinder; the connecting section (421) and the first cylinder (41) are gap-sealed; and a plurality of grooves are arranged on the inner wall of the containing section (422).

9. The refrigerator device according to claim 8, characterized in that: The power piston is designed as a hollow structure, and comprises a power piston housing (53) and a power piston end cover (54).

10. The refrigerator device according to claim 9, characterized in that The device further comprises a shell component and a cold finger component arranged at the lower end of the shell component; the vibration reduction component, the ejector structure and the power piston structure are arranged in the shell component and the cold finger component; the cold finger component comprises a cold finger base (81), a hot end heat dissipation copper ring (82), a heat regenerator shell (83), a cold end heat dissipation copper ring (84) and a cold finger end cover (85) which are coaxially connected in sequence; and a hot end heat dissipation filler (86), a heat regenerator (87), a cold end heat dissipation filler (88) which are arranged in sequence in the axial direction, a hot end limit steel ring (89), a heat regenerator limit ring (810) and a cold end limit steel ring (811) which are arranged in sequence in the axial direction.

Images