Patent Application
20250052452
The present disclosure relates to the technical field of refrigeration, and in particular, to an integrated Stirling refrigerator.
Cooled infrared detectors are able to detect a tiny temperature difference between a target and a background, which are not only suitable for detecting spatial, remote, dark and small targets, especially have advantages in the real-time high-resolution identification of ultra-high-speed, high-radar stealth targets, but also suitable for all-weather and independent use in complex electromagnetic environments, and have become the main technology for global multi-dimensional information acquisition and battlefield situational awareness. The cooled infrared detector components have been widely used in the new generation of infrared reconnaissance systems, precision-guided weapons, air defense and anti-missile warning equipment, and the application field has been expanding rapidly. The cooled infrared detectors have irreplaceable advantages in working range, target detection and tracking, especially in dynamic imaging of fast-moving targets. However, the cooled infrared detectors have a high cost and large size, which limits their battlefield applications.
With the progress of science and technology, technology research of the high operation temperature infrared detector device (HOT device) has made great breakthroughs, and the detector's operation temperature has been greatly improved. Some foreign mid-wave infrared detectors have their operation temperature increased to a 130-150K temperature range, and there is a trend to further increase it to 150-200K. The development success of the HOT devices has made it possible to develop a smaller, lighter, higher efficient ultra-compact Stirling refrigerator, which has also become a hotspot for the refrigerator development around the world.
With the increase of the operation temperature of infrared detectors, Stirling refrigerators have been developing towards smaller size, lighter weight, higher performance, lower power consumption and lower cost (referred to as SWaP3). Compared to linear motor-driven split Stirling refrigerators, rotary motor-driven integrated Stirling refrigerators have the advantages of compact structure, small size, light weight and low power consumption and the like, and can be widely used in infrared detectors of 80K temperature range.
Integrated Stirling refrigerators using a radial flux structure for rotary drive are known in the art. However, such integrated Stirling refrigerators have a large size along a length direction of an eccentric shaft, and there is still some room for reducing the size of the Stirling refrigerators.
The present disclosure is directed to an integrated Stirling refrigerator with small size and compact structure.
In one aspect, an integrated Stirling refrigerator may generally include an eccentric shaft box, an eccentric shaft, a stator assembly, a rotor assembly, a compression link assembly, and an expansion link assembly. The eccentric shaft box defines therein a sealed cavity filled with a gas medium. The eccentric shaft is provided rotatably around a rotation axis within the sealed cavity and includes an eccentric segment with its center line offset from the rotation axis and a non-eccentric segment with its center line coinciding with the rotation axis. The stator assembly is provided around the rotation axis and fixed within the sealed cavity. The rotor assembly is provided on the non-eccentric segment around the rotation axis, with an air gap formed between the rotor assembly and the stator assembly along an axial direction. The compression link assembly is provided within the sealed cavity and coupled to the eccentric segment. The expansion link assembly is provided within the sealed cavity and coupled to the eccentric segment. The stator assembly and the rotor assembly form an axial flux motor arranged in the axial direction and configured to drive the eccentric shaft to rotate about the rotation axis through the rotor assembly.
In some embodiments, the eccentric shaft box includes a housing and an end plate, the housing having an opening and the end plate being sealingly connected to the opening.
In some embodiments, the opening in the housing is circular in shape, and the end plate is in a shape of a circular plate matching the shape of the opening.
In some embodiments, the housing and the end plate are made of aluminum alloy, and the end plate and the housing are connected by a sealing ring or are sealingly welded.
In some embodiments, two ends of the eccentric shaft are connected to a bearing fixed to the housing and a bearing fixed to the end plate, respectively.
In some embodiments, one end of the eccentric shaft is connected to an inner ring of a deep groove ball bearing fixed inside the housing, and another end thereof is connected to an inner ring of a thrust ball bearing fixed to an inner side of the end plate.
In some embodiments, the stator assembly is fixed to the inner side of the end plate and is coaxially provided with respect to the thrust ball bearing.
In some embodiments, motor lead pins protrude from an outer side of the end plate, the motor lead pins extend through the end plate in the axial direction and are electrically isolated from the end plate through insulation sintering.
In some embodiments, the stator assembly includes a stator core and a winding. The stator core is provided with a bottom portion perpendicular to the axial direction, a plurality of teeth protruding from the bottom portion in the axial direction towards the rotor assembly. The winding includes a plurality of coils, each of which is arranged around and electrically isolated from a corresponding one of the teeth. The rotor assembly comprises a rotor disk and a plurality of permanent magnets. The rotor disk is mounted around the non-eccentric segment, the permanent magnets are fixed on a side of the rotor disk facing towards the stator assembly, and the permanent magnets are magnetized in the axial direction, with each two circumferentially adjacent permanent magnets having opposite polarities therebetween.
In some embodiments, an air gap between the rotor assembly and the stator assembly is 0.2 mm.
In another aspect, an integrated Stirling refrigerator may generally include a housing, an end plate, an eccentric shaft, and an axial flux motor. The housing may be configured to be a hollow structure and have an opening on one side thereof. The end plate is sealingly connected to the housing to close the opening, with a sealed cavity formed between the housing and the end plate. The eccentric shaft is rotatably arranged in the sealed cavity, the eccentric shaft defining a rotation axis and including an eccentric segment and a non-eccentric segment arranged along the rotation axis, the eccentric segment configured to be drivingly connected with a compression link assembly and an expansion link assembly. The axial flux motor is configured to drive the eccentric shaft to rotate about the rotation axis. The axial flux motor includes a stator assembly fixedly mounted to an inner side of the end plate, and a rotor assembly mounted on the non-eccentric segment for rotation with the non-eccentric segment, with an air gap formed between the rotor assembly and the stator assembly along an axial direction of the axial flux motor.
In some embodiments, the eccentric shaft has opposite two ends along the rotation axis, one end of the eccentric shaft is connected to one bearing fixed to the housing, and the other end of the eccentric shaft is connected to another bearing fixed to the inner side of the end plate.
In some embodiments, the stator assembly is fixed to the inner side of the end plate and is coaxially provided with respect to the another bearing.
In some embodiments, the one bearing is a deep groove ball bearing.
In some embodiments, the another bearing is a thrust ball bearing.
In some embodiments, motor lead pins extend through the end plate and configured for supplying power to the axial flux motor, and the motor lead pins are electrically isolated from the end plate through insulation sintering.
In some embodiments, the stator assembly comprises a stator core and a winding, the stator core comprises a bottom portion fixed to the inner side of the end plate, and a plurality of teeth protruding from the bottom portion in the axial direction towards the rotor assembly, and the winding is arranged around the teeth. The rotor assembly comprises a rotor disk and a plurality of permanent magnets; the rotor disk is mounted around the non-eccentric segment, the permanent magnets are fixed on a side of the rotor disk facing towards the stator assembly and spaced apart from each other along a circumferential direction of the rotor disk, and the permanent magnets are magnetized in the axial direction, with each two circumferentially adjacent permanent magnets having opposite polarities therebetween.
In the integrated Stirling refrigerator according to some embodiments, an axial flux motor is formed by the stator assembly and the rotor assembly and arranged in the axial direction of the eccentric shaft, which can reduce the size along the axial direction and make the overall structure more compact while maintaining the performance of the Stirling refrigerator. In addition, under the same outer diameter size, the axial flux motor has a higher torque density relative to the conventional radial flux motor, which can make the Stirling refrigerator have a smaller volume and weight, and lower power consumption.
The components in the figures are labeled as follows:
The technical solutions of the present disclosure are hereinafter described in further detail in connection with the drawings and specific embodiments.
Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which the present disclosure pertains. Terms used in the present disclosure are intended for describing specific embodiments only and are not intended to limit the manner in which the present disclosure can be realized. The term “and/or” as used herein is meant to cover any and all combinations of one or more of the relevant listed items.
In the description of the present disclosure, it is to be understood that the terms “center”, “up”, “down”, “front” “back”, “left”, “right”, “vertical”, “horizontal”, “top”, “bottom”, “inside”, “outside”, and other indications of the orientations or positional relationships are based on those shown in the figures and are intended only to facilitate the description of the present disclosure and to simplify the description, and are not intended to indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore are not to be construed as limitations of the present disclosure. In the description of the present disclosure, unless otherwise indicated, “plurality” means two or more.
In the description of the present disclosure, it is to be noted that, unless otherwise expressly specified and limited, the terms “mounted”, “connected”, “coupled” are to be understood in a broad sense. For example, it may be a fixed connection or a detachable connection, or a connection in one piece; it may be a direct connection, an indirect connection through an intermediate medium, or a connection between internal spaces of two elements. For those of ordinary skill in the art, the specific meaning of the above terms in the present disclosure may be understood in accordance with the specific circumstances.
In a radial flux motor, the direction of the magnetic flux is set to be along the radial direction perpendicular to the rotation axis, and the magnetic flux path is much longer compared to an axial flux motor, because the magnetic flux travels from one rotor pole to a first tooth of the stator, and then to a second tooth through a stator guard before it reaches another rotor pole. Unlike the radial flux motor, the axial flux motor has a magnetic flux direction parallel to the rotation axis and has a shorter and more direct flux path, with the flux path extending directly from one pole to another through an air gap. The shorter flux path of the magnetic field helps to increase the efficiency and power density of the motor. In addition, the axial flux motor has some advantages over the radial motor in terms of winding. Comparatively, the axial flux motor has more active winding copper and less overhang such that the ability to increase the number of turns is greater and less heat is caused by end effects. In sum, it can be seen that the axial flux motor can provide higher output power with less material and more compact construction, comparing with the radial flux motor.
To this end, on the basis of the above theoretical study, the present disclosure provides an integrated Stirling refrigerator, which, by adopting an axial flux motor to provide a rotary drive, not only achieves a reduction in size but it also can achieve a reduction in weight and power consumption. Referring to
The housing 10 is a hollow structure and has an opening 11 on one side thereof, the end plate 20 is sealingly connected to the side of the housing 10 where the opening 11 is located, and the housing 10 and the end plate 20 form an eccentric shaft box that is filled with a gas medium therein. More specifically, the opening 11 in the housing 10 is circular, the end plate 20 is in the shape of a circular plate matching the shape of the circular opening 11, and the end plate 20 closes the opening 11 from an outside to form a sealed cavity 12. The eccentric shaft 30, the stator assembly 40, the rotor assembly 50, the compression link assembly 80 and the expansion link assembly 90 are enclosed within the sealed cavity 12 inside the eccentric shaft box formed by the housing 10 and the end plate 20, and the sealed cavity 12 is filled with the high-pressure gas medium.
The housing 10 and the end plate 20 can be made of aluminum alloy. Sealing between the end plate 20 and the housing 10 can be achieved through a sealing ring or by means of welding, such that the sealed cavity 12 formed by them can withstand the high-pressure gas (such as helium) medium.
The eccentric shaft 30 defines a rotation axis 31, and the eccentric shaft 30 has an eccentric segment 32 with its center line offset from the rotation axis 31 and a non-eccentric segment 34 with its center line coinciding with the rotation axis 31. Both ends of the eccentric shaft 30 are mounted within the sealed cavity 12 formed by the housing 10 and the end plate 20 by means of bearings 60, and the eccentric segment 32 moves eccentrically about the rotation axis 31 as the eccentric shaft 30 rotates about the rotation axis 31. Specifically, one end of the eccentric shaft 30 is connected to an inner ring of one bearing 60 (such as a deep groove ball bearing) mounted in the housing 10, and the other end is connected to an inner ring of another bearing 60 (such as a thrust ball bearing) fixed on an inner side of the end plate 20, such that the eccentric shaft 30 can be mounted rotatably around the rotation axis 31 in the housing 10. The rotation axis 31 of the eccentric shaft 30 coincides with a center line of the opening 11 of the housing 10 and a center line of the end plate 20, and the thrust ball bearing can be embedded in a center hole of the end plate 20, enabling the stator assembly 40 and the rotor assembly 50 to withstand an axial force generated by the axial flux motor during the rotation of the motor.
The stator assembly 40 is fixedly mounted on the inner side of the end plate 20 (so the end plate 20 sometimes can also be referred to as a stator fixing plate) and is coaxially provided with respect to the thrust ball bearing, and the rotor assembly 50 is coaxially and fixedly mounted on the non-eccentric segment 34 of the eccentric shaft 30. An air gap 54 is formed between the rotor assembly 50 and the stator assembly 40 in an axial direction of the axial flux motor, such that the stator assembly 40 and the rotor assembly 50 form the axial flux motor which, upon being energized, generates power to drive the eccentric shaft 30 to rotate around the rotation axis 31. In a particular embodiment, the air gap 54 between the rotor assembly 50 and the stator assembly 40 is approximately 0.2 mm, facilitating the unobstructed rotation of the rotor assembly 50 without affecting the performance of the closed magnetic circuit.
Referring to
The rotor assembly 50 has a rotor disk 51 mounted around the non-eccentric segment 34 of the eccentric shaft 30, the rotor disk 51 having a center bore 55 receiving the non-eccentric segment 34 of the eccentric shaft 30 therein. A plurality of permanent magnets 52 is fixed to a side of the rotor disk 51 facing the stator assembly 40. Each of the permanent magnets 52 is inserted at least partially into a slot of the rotor disk 51, and is fixed to the slot of the rotor disk 51 by means of gluing, so that the permanent magnets 52 can be uniformly distributed along a circumferential direction of the rotor disk 5. Each permanent magnet 52 is magnetized along the axial direction, with each two circumferentially adjacent permanent magnets 52 having opposite polarities therebetween.
The stator assembly 40 is fixed on the inner side of the end plate 20, and motor lead pins 70 protrude from an outer side of the end plate 20. The motor lead pins 70 extend through the end plate 20 (stator fixing plate) in the axial direction, for supplying a three-phase alternating current (AC) power to the winding 43 of the stator assembly 40. The motor lead pins 70 may be electrically insulated from the end plate 20, such as, for example, by insulation sintering.
The insulation sintering between the motor lead pins 70 and the end plate 20, on one hand, ensures that the motor lead pins 70 are electrically isolated from the end plate 20 and, on the other hand, ensures that the high-pressure gas (helium) inside the housing 10 does not leak from around the motor lead pins 70.
The compression link assembly 80 and the expansion link assembly 90 are connected to the eccentric segment 32 of the eccentric shaft 30. Upon being driven by the rotation of the axial flux motor formed by the stator assembly 40 and the rotor assembly 50, the eccentric shaft 30 drives the compression link assembly 80 and the expansion link assembly 90 to perform eccentric movements. The compression link assembly 80 is configured to be connected to an end of a compression piston assembly located inside the housing 10, the expansion link assembly 90 is configured to be connected to an end of a pushing piston assembly located inside the housing 10, and an end of the pushing piston assembly located outside the housing 10 is configured to be connected to a regenerator.
The operation process of the above-described integrated Stirling refrigerator 100 is as follows: under the control of a motor drive controller, power is supplied to the stator assembly 40 through the motor lead pins 70; the winding 43 of the stator assembly 40 is energized to drive the rotor assembly 50 to rotate around the rotation axis 31, driving the eccentric shaft 30 to rotate around the rotation axis 31, which in turn drives the compression link assembly 80 and the expansion link assembly 90 connected to the eccentric segment 32 of the eccentric shaft 30 to carry out reciprocating motions. During the reciprocating motions of the compression link assembly 80 and the expansion link assembly 90 driven by the eccentric shaft 30, the pushing piston assembly makes a reciprocating linear motion to compress the high-pressure gas in the sealed cavity 12 of the housing 10, realizing a reverse Stirling cycle and obtaining cold energy, making the regenerator alternately exchange heat and produce cold energy.
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% more torque density compared to the traditional radial flux motor. With the increase of the operation temperature of the infrared detectors, the Stirling refrigerators have been developing in the direction of SWaP3, which enables the axial flux motor to bring into good play its advantages in size, weight and performance compared to the radial flux motor. The integrated Stirling refrigerator according to the present disclosure reduces the volume and weight of the refrigerator while maintaining the performance of the Stirling refrigerator by applying the rotary axial flux motor to the Stirling refrigerator. The adoption of this structural form can make the integrated Stirling refrigerator more compact, smaller in size and weight, and lower in power consumption.
It is to be noted that, in this disclosure, the terms “comprise”, “include” or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article or apparatus comprising a set of elements includes not only those elements but also other elements that are not expressly listed or that are inherent to such process, method, article or apparatus. Without further limitation, the fact that an element is defined by the phrase “include a . . . ” does not exclude the existence of another identical element in the process, method, article, or device including that element.
The foregoing are only specific embodiments of the present disclosure, but the scope of the present disclosure is not limited thereto. Any changes or substitutions that may be readily conceivable by those skilled in the art within the scope of the technology disclosed in the present disclosure shall fall into the scope of the present disclosure. Therefore, the scope of the present disclosure shall be determined based on the appended claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 202210874398.6 | Jul 2022 | CN | national |
| 202221913164.X | Jul 2022 | CN | national |
The present disclosure is a continuation of International Patent Application No. PCT/CN2023/070022 filed on Jan. 3, 2023 which claims the priority of China Patent Application Nos. 202210874398.6 and 202221913164.X, both filed on Jul. 21, 2022, the entire contents of which are incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/CN2023/070022 | Jan 2023 | WO |
| Child | 18932644 | US |
