Integrated stirling cryocooler

Abstract

The application provides an integrated Stirling cryocooler, comprising: an eccentric shaft box, having a sealed cavity filled with a gas working medium; an eccentric shaft, rotatably arranged in the sealed cavity along an axial direction, having an eccentric section and a non-eccentric section; a stator assembly, arranged along the axial direction and fixed in the sealed cavity; a rotor assembly, arranged on the non-eccentric section along the axial direction and having an air gap along the axial direction with the stator assembly; a compression connecting rod assembly, arranged in the sealed cavity and connected to the eccentric section; and an expansion connecting rod assembly, arranged in the sealed cavity and connected to the eccentric section; wherein the stator assembly and the rotor assembly form an axial flux motor arranged along the axial direction to drive the eccentric shaft to rotate along the axial direction by the rotor assembly. In the integrated Stirling cryocooler, the axial flux motor is formed by the stator assembly and the rotor assembly along the axial direction of the eccentric shaft, so that the size along the axial direction can be reduced, and the overall structure is more compact.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of refrigeration, in particular to an integrated Stirling cryocooler. BACKGROUND

[0002] The refrigeration type infrared detector can detect the tiny temperature difference between the target and the background, and is not only suitable for space, long-range and dark small target detection, especially has advantages in real-time high-resolution identification of super-high-speed and high-radar stealth targets, and is suitable for independent use in all-weather and complex electromagnetic environment, and becomes the main supporting technology of global multi-dimensional information acquisition and battlefield situation awareness. The refrigeration type infrared detector assembly has been widely used in new generation infrared reconnaissance systems, precision guided weapons, air defense and anti-missile early warning equipment, and the application field is rapidly expanding. The refrigeration type infrared detector has irreplaceable advantages in working range, target detection and tracking, especially dynamic imaging of fast-moving targets, but the cost of the refrigeration type detector is high, and the size is large, which limits its battlefield application.

[0003] With the progress of science and technology, great breakthroughs have been made in the technical research of high operation temperature (HOT) infrared detection devices, and the working temperature of the detector has been greatly improved. The working temperature of foreign medium wave infrared detectors has been increased to 130-150K temperature range, and there is a trend to further increase to 150-200K. The development of HOT devices makes it possible to develop smaller, lighter and more efficient ultra-small Stirling cryocoolers, which has become a research hotspot of cryocoolers at home and abroad.

[0004] With the increase of the working temperature of the infrared detector, the Stirling cryocooler has entered the development direction of smaller size, lower mass, higher performance, lower power consumption and lower cost (SWaP3 for short). The overall Stirling cryocooler driven by a rotating motor has the advantages of compact structure, small volume, light weight and low power consumption compared with the split Stirling cryocooler driven by a linear motor, and can be widely used in infrared detectors in the 80K temperature range.

[0005] The prior art discloses an overall Stirling cryocooler driven by a radial magnetic flux structure, but the size of the Stirling cryocooler along the length direction of the eccentric shaft is large, and the size of the Stirling cryocooler still has a certain reduction space. SUMMARY

[0006] Based on this, in order to solve the above technical problems, the present application provides an integrated Stirling cryocooler with small size and compact structure.

[0007] The embodiment of the present application provides an integrated Stirling cryocooler, which comprises:

[0008] An eccentric shaft box, having a sealed cavity filled with a gas working medium therein;

[0009] An eccentric shaft, rotatably arranged in the sealed cavity along an axial direction, having an eccentric section eccentric to the axial direction and a non-eccentric section along the axial direction;

[0010] A stator assembly, arranged along the axial direction and fixed in the sealed cavity;

[0011] A rotor assembly, arranged along the axial direction on the non-eccentric section and having an air gap along the axial direction with the stator assembly;

[0012] A compression connecting rod assembly, arranged in the sealed cavity and connected to the eccentric section; and

[0013] An expansion connecting rod assembly, arranged in the sealed cavity and connected to the eccentric section;

[0014] Wherein, the stator assembly and the rotor assembly form an axial flux motor arranged along the axial direction to drive the eccentric shaft to rotate along the axial direction by the rotor assembly.

[0015] In one embodiment, the eccentric shaft box comprises a shell having an opening and an end plate sealingly connected to the opening.

[0016] In one embodiment, the opening on the shell is circular, and the end plate is a circular plate matching the shape of the opening.

[0017] In one embodiment, the shell and the end plate are made of aluminum alloy material, and the end plate and the shell are sealingly connected by a sealing ring or welding.

[0018] In one embodiment, the two ends of the eccentric shaft are respectively connected to bearings fixed on the shell and bearings fixed on the end plate.

[0019] In one embodiment, one end of the eccentric shaft is connected to the inner ring of a deep groove ball bearing fixed in the shell, and the other end is connected to the inner ring of a thrust ball bearing fixed on the inner side of the end plate.

[0020] In one embodiment, the stator assembly is fixed on the inner side of the end plate and coaxially arranged with the thrust ball bearing.

[0021] In one embodiment, the outer side of the end plate protrudes a motor lead pin, which penetrates the end plate along the axial direction and forms electrical isolation between the end plate by insulation sintering.

[0022] In one of the embodiments, the stator assembly comprises a stator core and a winding, the stator core has a bottom surface perpendicular to the axial direction, a plurality of teeth extend from the bottom surface toward the rotor assembly along the axial direction, and the winding comprises a plurality of coils, each of the coils is arranged around the teeth and electrically isolated from the teeth.

[0023] The rotor assembly comprises a rotor disc and permanent magnets, the rotor disc is sleeved on the non- eccentric section, a plurality of permanent magnets are fixed on a side of the rotor disc facing the stator assembly, the permanent magnets are magnetized along the axial direction, and the polarities of the permanent magnets adjacent in the circumferential direction are opposite.

[0024] In one of the embodiments, the air gap between the rotor assembly and the stator assembly is 0.2 mm.

[0025] The integrated Stirling cryocooler has at least the following beneficial effects: in the integrated Stirling cryocooler, an axial flux motor is formed by the stator assembly and the rotor assembly in the axial direction of the eccentric shaft, the size in the axial direction can be reduced under the premise of ensuring the performance of the Stirling cryocooler, and the overall structure is more compact; in addition, the axial flux motor has an advantage of torque density over the traditional radial flux motor under the same outer diameter size, so that the volume and weight of the Stirling cryocooler are smaller, and the power consumption is lower. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 It is a sectional view of the integrated Stirling cryocooler of one of the embodiments of the present application.

[0027] Figure 2 It is a sectional view of the integrated Stirling cryocooler of one of the embodiments of the present application. Figure 1 It is an enlarged view of the integrated Stirling cryocooler in

[0028] Figure 3 It is an exploded view of the stator assembly and the rotor assembly in Figure 2

[0029] Reference signs of elements in the drawings are as follows:

[0030] Housing 10; end plate 20; eccentric shaft 30;

[0031] Stator assembly 40 (in which, stator core 41, tooth 42, winding 33);

[0032] Rotor assembly 50 (in which, rotor disc 51, permanent magnet 52);

[0033] Bearing 60; motor lead pin 70; compression linkage assembly 80; expansion linkage assembly 90;

[0034] Stirling cryocooler 100. DETAILED DESCRIPTION​

[0035] For the purposes of this application, the application will now be described in more detail with reference to the enclosed drawings. In the drawings, the preferred embodiments of the application are shown. The application may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and fully convey the scope of the application to those skilled in the art.

[0036] It should be noted that when an element is referred to as being "on" another element, it can be directly on the other element or intervening elements can also be present. When an element is referred to as being "connected" or "coupled" to another element, it can be directly connected or coupled to the other element or intervening elements can also be present. When an element is referred to as being "adjacent" to another element, it can be directly adjacent to the other element or intervening elements can also be present. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items. As used herein, the term "coupled" means the joining of two members directly or indirectly to one another. As used herein, the term "perpendicular" means a 90 degree angle between two members. As used herein, the terms "horizontal" and "vertical" refer to the relative positions of the members in the drawings. As used herein, the terms "left", "right", "upper", "lower", "up", "down", "under", and the like, are used for explanation only and are not to be construed as limiting terms. It is to be understood that the spatially relative terms are intended to encompass different orientations of the device in use or in operation, for example, if the device is turned over, a relative term such as "below" or "beneath" can be construed as being "above" or "over" other terms can be construed accordingly.

[0037] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in the description of the application herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. As used herein, the terms "and / or" and "and / or" include any and all combinations of one or more of the associated listed items.

[0038] In a radial flux motor, the magnetic flux direction is perpendicular to the rotation axis along the radial direction, and the magnetic flux path is much longer than that of an axial flux motor, because the magnetic flux path reaches the first tooth of the stator from one rotor pole, then reaches the second tooth through the stator back iron, and so on until reaching another rotor pole. Unlike the radial flux motor, the magnetic flux direction of the axial flux motor is parallel to the rotation axis, and the magnetic flux path is shorter and direct, reaching from one pole to another through the air gap. The shorter magnetic flux path of the magnetic field helps to improve the efficiency and power density of the motor. In addition, the axial flux motor also has certain advantages in winding compared with the radial motor. The axial flux motor has relatively higher active winding copper and less overhang, so it has stronger ability to increase the number of turns and less heat caused by end effect. In summary, the axial flux motor can provide higher output power with less material and more compact structure compared with the radial flux motor.

[0039] Based on the above theoretical research, the application provides an integrated Stirling refrigerator, which is driven by an axial flux motor to achieve the effects of reducing size, weight and power consumption. Please refer to Figure 1 The integrated Stirling refrigerator 100 of an embodiment of the application comprises a shell 10, an end plate 20, an eccentric shaft 30, a stator assembly 40, a rotor assembly 50, a compression connecting rod assembly 80 and an expansion connecting rod assembly 90. The eccentric shaft 30, the stator assembly 40, the rotor assembly 50, the compression connecting rod assembly 80 and the expansion connecting rod assembly 90 are all installed in the space formed by the shell 10 and the end plate 20. The rotor assembly 50, the compression connecting rod assembly 80 and the expansion connecting rod assembly 90 are all installed on the eccentric shaft 30. The stator assembly 40 and the rotor assembly 50 form an axial flux motor to provide power for driving the eccentric shaft 30 to rotate. The rotation of the eccentric shaft 30 drives the compression connecting rod assembly 80 and the expansion connecting rod assembly 90 to compress and expand respectively, thereby realizing refrigeration.

[0040] The shell 10 is a hollow structure with an opening on one side. The end plate 20 is sealingly connected to the opening of the shell 10, and the shell 10 and the end plate 20 form an eccentric shaft box filled with gas working medium. More specifically, the opening on the shell 10 is circular, and the end plate 20 is a circular plate matching the shape of the circular opening. The end plate 20 closes the opening from the outside to form a sealed cavity. The eccentric shaft 30, the stator assembly 40, the rotor assembly 50, the compression connecting rod assembly 80 and the expansion connecting rod assembly 90 are all enclosed in the sealed cavity inside the eccentric shaft box formed by the shell 10 and the end plate 20, and the sealed cavity is filled with high-pressure gas working medium.

[0041] The shell 10 and the end plate 20 can be made of aluminum alloy material, and the end plate 20 and the shell 10 are sealed by a sealing ring or welding, so that the sealed cavity formed by the two can withstand high-pressure gas (helium) working medium.

[0042] The eccentric shaft 30 defines an axial direction, and has an eccentric section eccentric to the axial direction and a non-eccentric section along the axial direction. The two ends of the eccentric shaft 30 are installed in the sealed cavity formed by the shell 10 and the end plate 20 through bearings 60, and the eccentric section performs eccentric motion around the axial direction when the eccentric shaft 30 rotates around the axial direction. Specifically, one end of the eccentric shaft 30 is connected to the inner ring of the bearing 60 (deep groove ball bearing) installed in the shell 10, and the other end is connected to the inner ring of the bearing 60 (thrust ball bearing) fixed to the inner side of the end plate 20, so that the eccentric shaft 30 is rotatably installed in the shell 10 around the axis. The axial direction of the eccentric shaft 30 coincides with the center line of the opening of the shell 10 and the center line of the end plate 20, and the thrust ball bearing is embedded in the center hole position of the end plate 20, for the stator assembly 40 and the rotor assembly 50 to bear the axial force generated during the rotation of the axial flux motor.

[0043] The stator assembly 40 is fixedly installed on the inner side of the end plate 20 and coaxially arranged with the thrust ball bearing, and the rotor assembly 50 is coaxially fixedly installed on the non-eccentric section of the eccentric shaft 30. The rotor assembly 50 and the stator assembly 40 form an air gap along the axial direction, so that the stator assembly 40 and the rotor assembly 50 form an axial flux motor, which generates driving power for rotating the eccentric shaft 30 around the axial direction after being energized. In a specific embodiment, the air gap between the rotor assembly 50 and the stator assembly 40 is about 0.2 mm, which facilitates the unobstructed rotation of the rotor assembly 50 while not affecting the performance of the closed magnetic circuit.

[0044] Please refer to Figure 2 and Figure 3 , the stator assembly 40 includes a stator core 41 and a winding 43, the stator core 41 has a bottom surface perpendicular to the axial direction, and a plurality of teeth 42 extend from the bottom surface along the axial direction towards the rotor assembly 50, and a winding receiving groove (see Figure 3 ) is formed between adjacent teeth 42. The winding 43 is a three-phase electric winding, which includes a plurality of coils, each coil being arranged around the teeth 42 of the stator core 41 and being electrically isolated from the teeth 42 by an insulating tape.

[0045] The rotor assembly 50 has a rotor disc 51, the central hole of the rotor disc 51 is sleeved on the non- eccentric section of the eccentric shaft 30, and a plurality of permanent magnets 52 are fixed on the side of the rotor disc 51 facing the stator assembly 40. Each permanent magnet 52 at least partially passes through the hole of the rotor disc 51 and is fixed on the hole of the rotor disc 51 by adhesion to be uniformly distributed relative to the circumferential direction of the rotor disc 51. The permanent magnets 52 are magnetized axially along the mounting position, and the polarities of two permanent magnets 52 circumferentially adjacent to each other are opposite.

[0046] The inner side of the end plate 20 is fixed with the stator assembly 40, and the outer side of the end plate 20 protrudes the motor lead pin 70 which penetrates the end plate 20 (stator fixing plate) along the axial direction, and forms electrical isolation between the motor lead pin 70 and the end plate 20 (stator fixing plate) through insulation sintering, so as to provide three-phase alternating current for the winding 43 of the stator assembly 40.

[0047] The insulation sintering between the motor lead pin 70 and the end plate 20 can not only ensure the insulation and non-conduction between the motor lead pin 70 and the end plate 20, but also ensure that the high-pressure gas (helium) in the shell 10 will not leak from around the motor lead pin 70.

[0048] The compression connecting rod assembly 80 and the expansion connecting rod assembly 90 are connected to the eccentric section of the eccentric shaft 30. Under the rotary drive of the axial magnetic flux motor formed by the stator assembly 40 and the rotor assembly 50, the eccentric shaft 30 drives the compression connecting rod assembly 80 and the expansion connecting rod assembly 90 to perform eccentric motion. The compression connecting rod assembly 80 is connected to one end of the compression piston assembly in the shell 10, the expansion connecting rod assembly 90 is connected to one end of the displacement piston assembly in the shell 10, and the other end of the displacement piston assembly is connected to the regenerator outside the shell 10.

[0049] The working process of the integrated Stirling refrigerator 100 is as follows: under the control of the motor drive controller, the stator assembly 40 is powered through the motor lead pin 70, the winding 43 of the stator assembly 40 is energized to drive the rotor assembly 50 to rotate around the axial direction, drive the eccentric shaft 30 to rotate around the axial direction, and the eccentric section of the eccentric shaft 30 connects the compression connecting rod assembly 80 and the expansion connecting rod assembly 90 to perform reciprocating motion. In the process of reciprocating motion of the compression connecting rod assembly 80 and the expansion connecting rod assembly 90 driven by the eccentric shaft 30, the displacement piston assembly performs reciprocating linear motion to compress the high-pressure gas in the sealed cavity of the shell 10, realizes reverse Stirling cycle, obtains cold energy, and makes the regenerator alternately exchange heat and generate cold energy.

[0050] The rotary axial flux motor has the advantages of small size, light weight, high power density, etc. Under the same outer diameter size, the axial flux motor can provide 30% torque density advantage compared with the traditional radial flux motor. With the improvement of the working temperature of the infrared detector, the Stirling cryocooler develops in the direction of SWaP3, and the axial flux motor can better play the advantages of volume, weight and performance compared with the radial flux motor. The integrated Stirling cryocooler of the application applies the rotary axial flux motor to the Stirling cryocooler, reduces the volume and weight of the cryocooler under the premise of ensuring the performance of the Stirling cryocooler. The structure can make the integrated Stirling cryocooler more compact, smaller in size and weight, and lower in power consumption.

[0051] The technical features of the above-described embodiments can be combined in any manner. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described, but as long as the combinations of the technical features do not exist contradictions, they should be considered as the scope of the present application.

[0052] The above-described embodiments only express several implementation manners of the application, and the description is more specific and detailed, but it should not be understood as a limitation on the scope of the patent. It should be pointed out that for ordinary skilled in the art, without departing from the concept of the application, some modifications and improvements can be made, which are all within the protection scope of the application. Therefore, the protection scope of the patent of the application should be subject to the appended claims.

Claims

1. An integrated stirling cryocooler characterized by, The eccentric shaft box comprises: an eccentric shaft box with a sealed cavity filled with gas working medium inside; an eccentric shaft (30) rotatably arranged in the sealed cavity along an axial direction, having an eccentric section eccentric to the axial direction and a non-eccentric section along the axial direction; a stator assembly (40) arranged along the axial direction and fixed in the sealed cavity; a rotor assembly (50) arranged on the non-eccentric section along the axial direction and having an air gap with the stator assembly (40) along the axial direction; a compression connecting rod assembly (80) arranged in the sealed cavity and connected to the eccentric section; and an expansion connecting rod assembly (90) arranged in the sealed cavity and connected to the eccentric section; wherein the stator assembly (40) and the rotor assembly (50) form an axial flux motor arranged along the axial direction to drive the eccentric shaft (30) to rotate along the axial direction by the rotor assembly.

2. An integrated stirling refrigerator according to claim 1, characterised in that: The eccentric shaft box comprises an outer shell (10) with an opening and an end plate (20) sealingly connected to the opening.

3. An integrated stirling refrigerator according to claim 2, characterised in that: The opening on the outer shell (10) is circular, and the end plate (20) is a circular plate matching the shape of the opening.

4. An integrated stirling refrigerator according to claim 2, characterised in that: The outer shell (10) and the end plate (20) are made of aluminum alloy material, and the end plate (20) is sealingly connected to the outer shell (10) by a sealing ring or welding.

5. An integrated stirling refrigerator according to claim 2, characterised in that: Both ends of the eccentric shaft (30) are connected to bearings (60) fixed on the outer shell (10) and the end plate (20), respectively.

6. An integrated stirling refrigerator according to claim 5, characterised in that: One end of the eccentric shaft (30) is connected to the inner ring of a deep groove ball bearing fixed in the outer shell (10), and the other end is connected to the inner ring of a thrust ball bearing fixed on the inner side of the end plate (20).

7. An integrated stirling refrigerator according to claim 6, characterised in that: The stator assembly (40) is fixed on the inner side of the end plate (20) and coaxially arranged with the thrust ball bearing.

8. An integrated stirling refrigerator according to claim 2, characterised in that: The outer side of the end plate (20) protrudes a motor lead pin (70) which penetrates the end plate (20) along the axial direction and forms electrical isolation between the end plate (20) by insulation sintering.

9. An integrated stirling refrigerator according to any one of claims 1 to 8, characterised in that: The stator assembly (40) comprises a stator core (41) having a bottom surface perpendicular to the axial direction, a plurality of teeth (42) extending from the bottom surface along the axial direction towards the rotor assembly (50), and a winding (43) comprising a plurality of coils, each coil being arranged around the teeth (42) and electrically isolated from the teeth (42). The rotor assembly (50) comprises a rotor disc (51) and a plurality of permanent magnets (52) fixed on the side of the rotor disc (51) facing the stator assembly (40), the permanent magnets (52) being magnetized along the axial direction and having opposite polarities between adjacent permanent magnets (52) in the circumferential direction.

10. An integrated stirling refrigerator according to claim 9, characterised in that: The air gap between the rotor assembly (50) and the stator assembly (40) is 0.2 mm.

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