Cylinder device for Stirling cryocooler

Abstract

The invention discloses an air cylinder device for a Stirling cryocooler, which is provided with a compression cavity communicated with an expansion cavity of an expansion machine, and comprises a floating cylinder body, a flexible connecting piece and an end cover which are axially and hermetically connected in sequence, a piston is arranged in the floating cylinder body, is connected with the driving mechanism, can axially move along the floating cylinder body under the driving of the driving mechanism, and compresses gas in the compression cavity; the end cover is fixed on the mounting box, and the floating cylinder body is not fixedly mounted on the mounting box, is connected with the flexible connecting piece and the end cover in sequence, and is fixed on the mounting box through the end cover; the flexible connecting piece can be adaptively deformed to allow the floating cylinder body which is laterally impacted by the piston to float within the preset range, so that the radial lateral force between the piston and the air cylinder can be reduced, the friction loss between the piston and the air cylinder is reduced, the efficiency of the air cylinder device is improved, and the service life of the air cylinder device is prolonged.

Description

Technical Field

[0001] The present invention relates to the technical field of compression cylinders, in particular to a cylinder device for a Stirling refrigerator. Background Art

[0002] A rotary integrated Stirling refrigerator is a highly efficient refrigeration device based on the Stirling cycle. In this refrigerator, the compressor and expander are integrated into one unit, typically connected by a connecting pipe. During the refrigeration cycle, the compressor compresses the gas, increasing its pressure before transporting it to the expander via the connecting pipe. In the expander, the gas expands and cools, then returns to the compressor via the connecting pipe, completing the refrigeration cycle. Therefore, the cyclic compression and expansion of gas (usually helium) can be used to maintain a constant low temperature at the cold end, leading to its widespread use in the infrared field. For example, a rotary integrated Stirling refrigerator is used to provide a low-temperature operating environment for mercury cadmium telluride (HgCdTe) detectors. Furthermore, rotary integrated Stirling refrigerators offer the advantages of compact structure, light weight, and high efficiency.

[0003] The compressor drive mechanism of a rotary integrated Stirling refrigerator utilizes a crank-connecting rod mechanism. Driven by a motor, the crank-connecting rod mechanism drives the piston axially within the compression cylinder, compressing the gas within the compression cylinder and discharging the compressed gas into the expansion chamber of the expander. However, as the piston moves under the drive of the crank-connecting rod mechanism, it is subjected to a force component along the radial direction of the cylinder, causing the piston to impact the cylinder radially, generating lateral forces and friction losses between the piston and cylinder.

[0004] A large number of studies have shown that the failure mechanisms of refrigerators mainly include working fluid leakage, mechanical wear, fatigue fracture, working fluid contamination, etc. Among them, mechanical wear is related to the moving parts of the refrigerator, and wear between the piston and the cylinder is an important factor leading to refrigerator failure.

[0005] At present, the life of infrared detectors is as long as several years to more than ten years, while the life of rotary integrated Stirling refrigerators is often only a few thousand hours to ten thousand hours. When the infrared detector is integrated with the Stirling refrigerator, the life of the rotary integrated Stirling refrigerator seriously restricts the life of the entire infrared detector.

[0006] Therefore, the present invention aims to provide a cylinder device for a Stirling refrigerator, which is used to reduce the wear between the piston and the compression cylinder, thereby increasing the overall life of the Stirling refrigerator. Summary of the Invention

[0007] The present invention provides a cylinder device for a Stirling refrigerator, which is used to reduce the wear between a piston and a compression cylinder, thereby increasing the overall service life of the Stirling refrigerator.

[0008] The present invention provides a cylinder device for a Stirling refrigerator, wherein the cylinder device has a compression chamber connected to an expansion chamber of an expander, and the cylinder device comprises a floating cylinder body, a flexible connector, and an end cover which are sequentially axially sealed;

[0009] A piston is provided in the floating cylinder, the piston being connected to a driving mechanism and being driven by the driving mechanism to move axially along the floating cylinder and compress the gas in the compression chamber;

[0010] The end cover is fixed on the installation box, and the floating cylinder is configured to float relative to the installation box after being radially impacted by the piston. The flexible connector adaptively bends and / or telescopically deforms as the floating box floats, and absorbs the energy generated by the impact on the floating cylinder.

[0011] As an embodiment, the flexible connector includes a corrugated section having a trough, the corrugated section is made of a metal material, and the wall thickness of the corrugated section is 0.15 mm to 0.25 mm.

[0012] As an embodiment, the corrugated section has a triangular wave shape, and the surfaces where two adjacent sides of the trough on the corrugated section are located intersect to form a trough angle, and the trough angle is 50° to 60°.

[0013] As an embodiment, the corrugated segment is formed by connecting a first ring segment and a second ring segment that are bendable in the middle, and the trough is formed at the connection between the two;

[0014] The end of the first ring segment away from the trough is a first fixed end and is fixed to the floating cylinder body, and the end of the second ring segment away from the trough is a second fixed end and is fixed to the end cover. The height difference between the first fixed end and the trough is not greater than the height difference between the second fixed end and the trough.

[0015] As an embodiment, the flexible connector further includes:

[0016] a first connecting section, one end surface of which is connected to the first fixed end, and the other end surface of which is in close contact with the end surface of the floating cylinder, wherein the first fixed end is fixed to the floating cylinder through the first connecting section;

[0017] When the flexible connector is in an undeformed initial state, the first connecting segment is perpendicular to the central axis of the corrugated segment, and the angle between the first connecting segment and the first ring segment is 25° to 30°.

[0018] As an embodiment, the compression chamber is defined by the inner wall of the floating cylinder, the piston end face, the flexible connector and the end cover;

[0019] An air flow channel is formed on the end cover, one end of the air flow channel is communicated with the compression chamber, and the other end passes through the end cover and is communicated with the expansion chamber of the expander.

[0020] As an embodiment, a first installation cavity is formed in the installation box, and the floating cylinder is installed in the first installation cavity with a buffer member provided therebetween;

[0021] When the floating cylinder floats and presses the buffer member, the buffer member can buffer and absorb energy of the floating cylinder.

[0022] As an embodiment, the buffer is annular and is arranged on the floating cylinder along the circumference of the floating cylinder;

[0023] The outer annular surface of the buffer component is loosely matched with the inner wall of the first installation cavity.

[0024] As an embodiment, a mounting groove is circumferentially formed on the outer wall of the floating cylinder, the buffer is embedded in the mounting groove, and the inner annular surface of the buffer is interference fit with the inner bottom wall of the mounting groove.

[0025] As an embodiment, the driving mechanism is a crank-connecting rod mechanism, including a crankshaft, a crank and a transmission rod, wherein the crankshaft is rotatably arranged on the mounting box; the crankshaft is connected to the motor driving, and the crankshaft is fixed to the crank;

[0026] One end of the transmission rod is rotationally connected to the crank, and the other end of the transmission rod is rotationally connected to the piston.

[0027] Compared with the prior art, the advantages of the present invention are:

[0028] 1. In an embodiment of the present invention, the floating cylinder is not fixedly mounted on the mounting box. Instead, it is sequentially connected to a flexible connector and an end cap, which is then fixed to the mounting box by the end cap. The flexible connector is adaptively deformable to allow the floating cylinder to float within a preset range when subjected to a lateral impact from the piston. This reduces the radial contact force (lateral force) between the piston and the cylinder, thereby reducing frictional losses between the piston and the cylinder and extending the efficiency and life of the cylinder assembly.

[0029] 2. In an embodiment of the present invention, a buffer is provided between the floating cylinder and the inner wall of the first installation cavity of the installation box; the floating cylinder floats radially in the first installation cavity after being subjected to the radial impact of the piston. When the floating cylinder floats to a certain extent, the floating cylinder squeezes the buffer, and the buffer is squeezed and deformed to buffer and absorb energy of the floating cylinder, thereby preventing the floating cylinder from hitting the inner wall of the first installation cavity. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Hereinafter, the present invention will be described in more detail based on embodiments with reference to the accompanying drawings.

[0031] Figure 1 2 is a schematic structural diagram of a cylinder device for a Stirling refrigerator according to an embodiment of the present invention;

[0032] Figure 2 yes Figure 1 Cross-sectional view of the cylinder device for the Stirling refrigerator in the AA direction;

[0033] Figure 3 yes Figure 1 A partial enlarged view of the buffer component is shown;

[0034] Figure 4 It is a structural diagram of a buffer;

[0035] Figure 5 It is the main view of the buffer;

[0036] Figure 6 It is a schematic diagram of the buffer in the BB direction.

[0037] Reference numerals:

[0038] 1. Floating cylinder; 11. Mounting slot;

[0039] 2. Flexible connector; 21. Corrugated section; 210. Wave trough; 211. First ring section; 212. Second ring section; 22. First connecting section; 23. Second connecting section;

[0040] 3. End cap; 31. Cap body; 32. Connecting part;

[0041] 4. Installation box; 41. First installation cavity; 42. Second installation cavity;

[0042] 5. Buffer parts;

[0043] 6. Driving mechanism; 61. Crankshaft; 62. Crank; 63. Transmission rod;

[0044] 7. Piston; 8. Pin. DETAILED DESCRIPTION

[0045] The present invention will be further described below with reference to the accompanying drawings.

[0046] A rotary integrated Stirling refrigerator is a highly efficient refrigeration device based on the Stirling cycle. The compressor and expander are connected by a connecting pipe. The cyclic compression and expansion of the gas maintains a continuously low temperature at the cold end. During the refrigeration cycle, the compressor compresses the gas, increasing its pressure before transferring it to the expander via a connecting pipe. In the expander, the gas expands, cooling it, and then returns to the compressor through a connecting pipe, completing the refrigeration cycle.

[0047] An embodiment of the present invention provides a cylinder device for a Stirling refrigerator. The cylinder device is a compression cylinder of a compressor and has a compression chamber. The compression chamber is connected to an expansion chamber of an expander through a connecting pipe.

[0048] The cylinder device includes a floating cylinder body 1, a flexible connector 2, an end cover 3, a piston 7, a mounting box 4 and a driving mechanism 6.

[0049] A piston 7 is provided in the floating cylinder 1. The piston 7 is connected to the driving mechanism 6 and can move axially along the floating cylinder 1 under the drive of the driving mechanism 6 to compress the gas in the compression chamber; the floating cylinder 1, the flexible connector 2 and the end cover 3 are axially sealed and connected in sequence, and the end cover 3 is fixed on the installation box 4. After being radially impacted by the piston 7, the floating cylinder 1 can float relative to the installation box 4. At the same time, the flexible connector 2 adaptively bends and / or telescopically deforms to absorb the energy generated by the impact on the floating cylinder 1.

[0050] In the embodiment of the present invention, the floating cylinder body 1 is not fixedly mounted on the mounting box 4, but is connected in sequence to the flexible connector 2 and the end cover 3, and is fixed to the mounting box 4 by the end cover 3; the flexible connector 2 can be adaptively deformed to allow the floating cylinder body 1 subjected to the lateral impact of the piston 7 to float within a preset range, thereby reducing the radial contact force (lateral force) between the piston 7 and the cylinder, thereby reducing the friction loss between the piston 7 and the cylinder, and extending the efficiency and life of the cylinder device.

[0051] The flexible connector 2 includes a corrugated section 21 having a trough 210 . The corrugated section 21 is made of metal, and the wall thickness of the corrugated section 21 is 0.15 mm to 0.25 mm.

[0052] Preferably, the wall thickness of the corrugated section 21 is 0.2 mm. When the flexible connector 2 is undeformed, the inner diameter at the trough 210 is 14 mm. The ratio of the wall thickness to the inner diameter at the trough 210 is 0.014, which is relatively small and facilitates the swinging of the connector. The corrugated section 21 has a triangular wave shape, and the intersection of the two adjacent sides of the trough 210 on the corrugated section 21 forms a trough 210 angle, which is 50° to 60°.

[0053] The corrugated section 21 is formed by connecting a first ring section 211 and a second ring section 212 which can be bent in the middle, and a trough 210 is formed at the connection between the two; the end of the first ring section 211 away from the trough 210 is a first fixed end and is fixed to the floating cylinder body 1, and the end of the second ring section 212 away from the trough 210 is a second fixed end and is fixed to the end cover 3, the height difference α between the first fixed end and the trough 210 is h1, and the height difference between the second fixed end and the trough 210 is h2, and h1 is not greater than h2.

[0054] The first ring segment 211 and the second ring segment 212 are laser welded, with the weld located near the inner wall of the corrugated segment 21. Laser welding offers advantages such as high weld quality, concentrated energy during welding, and rapid melting of the welded portion, which helps ensure precision. It is also clean and environmentally friendly, as the cleanliness of parts within a refrigerator is highly demanding, requiring minimal foreign matter. Laser welding eliminates excess debris, resulting in a cleaner surface after welding.

[0055] It should be noted that the welded surface of the corrugated section 21 after welding has burrs and sharp edges. Polishing equipment is required to remove these burrs and sharp edges to prevent the corrugated section 21 from breaking along these defects during long-term use. The polishing equipment is preferably a vibrating grinding and polishing machine, using 1mm diameter white corundum balls as the polishing material.

[0056] In the embodiment of the present invention, the flexible connector 2 further includes a first connecting section 22 and a second connecting section 23 .

[0057] The first connecting segment 22 is a stamped metal ring. One end face of the first connecting segment 22 is welded to the first fixed end, with the weld point close to the outer edge of the first connecting segment 22. The weld is formed on the outer surface of the first ring segment 211 and positioned near the outer periphery to improve welding stability. When the flexible connector 2 is in its undeformed initial state, the first connecting segment 22 is perpendicular to the central axis of the corrugated segment 21. The angle α between the first connecting segment 22 and the first ring segment 211 is controlled within the range of 25° to 30°.

[0058] The side wall of the first connecting section 22 facing away from the first ring section 211 is welded and fixed to the end face of the floating cylinder body 1. The first fixed end is fixed to the floating cylinder body 1 through the first connecting section 22, which can improve the sealing and connection stability between the flexible connecting member 2 and the floating cylinder body 1.

[0059] The second connecting segment 23 is a stamped metal ring. One end face of the second connecting segment 23 is welded to the second fixed end of the second ring segment 212. The weld is located near the outer edge of the second connecting segment 23. The weld is formed on the outer surface of the second ring segment 212 and is located near the outer periphery to improve welding stability. When the flexible connector 2 is in its undeformed initial state, the second connecting segment 23 is perpendicular to the central axis of the corrugated segment 21. The angle β between the second connecting segment 23 and the second ring segment 212 is controlled within the range of 25° to 30°. Preferably, β = α.

[0060] The end surface of the second connecting section 23 facing away from the second ring section 212 is welded and fixed to the end cover 3. The second fixed end is fixed to the end cover 3 through the second connecting section 23 to improve the sealing and connection stability between the flexible connector 2 and the end cover 3.

[0061] In this embodiment of the present invention, the compression chamber is defined by the inner wall of the floating cylinder 1, the end surface of the piston 7, the flexible connector 2, and the end cap 3. An airflow channel is formed in the end cap 3, one end of which communicates with the compression chamber and the other end of which penetrates the end cap 3 and connects to the expansion chamber of the expander. When the piston 7 moves axially within the cylinder to compress gas, the compressed gas is discharged into the expansion chamber of the expander through the gas channel in the end cap 3 and the connecting pipe.

[0062] To install the floating cylinder 1, a first installation cavity 41 is formed on the installation box 4. The floating cylinder 1 is accommodated and installed in the first installation cavity 41 of the installation box 4. One axial end of the first installation cavity 41 has an installation opening, through which the floating cylinder 1 can be placed into the first installation cavity 41 for easy installation.

[0063] In an embodiment of the present invention, a buffer member 5 is provided between the floating cylinder body 1 and the inner wall of the first installation cavity 41 of the installation box 4; the floating cylinder body 1 floats radially in the first installation cavity 41 after being radially impacted by the piston 7. When the floating cylinder body 1 floats to a certain extent, the floating cylinder body 1 squeezes the buffer member 5, and the buffer member 5 is squeezed and deformed and buffers and absorbs energy of the floating cylinder body 1, thereby preventing the floating cylinder body 1 from hitting the inner wall of the first installation cavity 41.

[0064] In this embodiment, the buffer member 5 is annular and circumferentially surrounds the floating cylinder 1. The outer surface of the buffer member 5 is loosely coupled with the inner wall of the first mounting cavity 41. The floating cylinder 1 floats under the radial impact of the piston 7. When the floating cylinder 1 reaches a predetermined floating range, the floating cylinder 1 and the inner wall of the first mounting cavity 41 on the mounting box 4 press against the buffer member 5, preventing collision between the floating cylinder 1 and the mounting box 4.

[0065] Specifically, a mounting groove 11 is circumferentially defined on the outer wall of the floating cylinder 1. The buffer 5 is inserted into the mounting groove 11, with its inner annular surface forming an interference fit with the inner bottom wall of the mounting groove 11. This arrangement allows the buffer 5 to be tightly secured to the floating cylinder 1. When the floating cylinder 1 is subjected to radial impact from the piston 7, the buffer 5 is pulled along with it, preventing it from separating from the floating cylinder 1. This improves the stability of the connection between the two and ensures that the buffer 5 effectively cushions the floating cylinder 1.

[0066] The buffer 5 is configured so that its thickness is slightly less than the width of the mounting groove 11 when undeformed. When the floating cylinder 1 floats to a predetermined amplitude and compresses the buffer 5, the buffer 5 deforms along its thickness to cushion the floating cylinder 1. The appropriate width of the mounting groove 11 provides a sufficient deformation margin for the buffer 5. As the buffer 5 continues to deform, its two end faces along the thickness direction abut against the inner sidewalls of the mounting groove 11, limiting further deformation and preventing radial crushing of the buffer 5.

[0067] In this embodiment, a plurality of buffer members 5 are provided, one for each buffer member 5, within the mounting slots 11 of the floating cylinder 1. The buffer members 5 are spaced apart along the axial direction of the floating cylinder 1. When the floating cylinder 1 tilts during floating, the buffer members 5 deform to varying degrees, thereby providing a cushioning effect on the floating cylinder 1.

[0068] In an embodiment of the present invention, the end cover 3 includes a cover body 31 and a connecting portion 32 that are integrally molded and connected, wherein the cover body 31 is used to be sealed and connected to the flexible connector 2; one axial end of the connecting portion 32 is connected to the cover body 31 by a screw, and the other axial end of the connecting portion 32 is connected to the installation box 4 near the first installation cavity 41.

[0069] Preferably, the diameter of the cover body 31 is larger than the outer diameter of the floating cylinder body 1, and the diameter of the cover body 31 matches the mounting port of the first mounting cavity 41 to block the mounting port of the first mounting cavity 41 to prevent external dust particles or moisture from entering the first mounting cavity 41 through the mounting port, thereby protecting the floating cylinder body 1, the buffer 5 and the flexible connector 2 to prevent rust or wear.

[0070] Next, the driving mechanism 6 and the driving method of the piston 7 will be described.

[0071] In this embodiment of the present invention, the drive mechanism 6 can be a crank-connecting rod mechanism, comprising a crankshaft 61, a crank 62, and a transmission rod 63. The crankshaft 61 is rotatably mounted on the mounting box 4. A protrusion 62 is formed on the crankshaft 61, eccentrically disposed relative to the rotational centerline of the crankshaft 61. The crank 62 is defined by the protrusion. One end of the transmission rod 63 is rotationally connected to the crank 62, and the other end of the transmission rod 63 is rotationally connected to the piston 7. The crankshaft 61 is connected to a motor drive. Driven by the motor, the crankshaft 61 rotates, and the crank 62 rotates with the crankshaft, driving the transmission rod 63 to move. The transmission rod 63, in turn, drives the piston 7 to reciprocate, thereby compressing the gas in the compression chamber.

[0072] The rotational connection between the piston 7 and the transmission rod 63 is as follows: a pin 8 extending radially along the floating cylinder body 1 is fixed on the piston 7, and a bearing is fixed on the pin 8. The outer ring of the bearing is fixed to the transmission rod 63, so that a rotatable connection between the piston 7 and the transmission rod 63 can be achieved.

[0073] The transmission rod 63 and the crank 62 are rotatably connected in the following manner: the transmission rod 63 and the crank 62 are connected via a bearing, the inner ring of the bearing is coaxially sleeved and fixed on the crank 62, and the outer ring of the bearing is fixedly mounted on the transmission rod 63.

[0074] A second installation cavity 42 communicating with the first installation cavity 41 is formed in the installation box 4 . The crankshaft 61 is rotatably installed in the second installation cavity 42 , and the crankshaft 61 is arranged parallel to the pin shaft 8 .

[0075] While the present invention has been described with reference to preferred embodiments, various modifications may be made and equivalent components may be substituted without departing from the scope of the present invention. In particular, the various technical features described in the various embodiments may be combined in any manner, provided no structural conflicts exist. The present invention is not limited to the specific embodiments disclosed herein, but encompasses all technical solutions within the scope of the claims.

Claims

1. A cylinder device for a Stirling refrigerator, characterized in that: It has a compression chamber connected to the expansion chamber of the expander, and the cylinder device includes a floating cylinder body, a flexible connector and an end cover which are axially sealed and connected in sequence; A piston is provided in the floating cylinder, the piston being connected to a driving mechanism and being driven by the driving mechanism to move along the axial direction of the floating cylinder and compress the gas in the compression chamber; The end cover is fixed on the installation box, and the floating cylinder is configured to float relative to the installation box after being radially impacted by the piston. The flexible connector adaptively bends and / or telescopically deforms as the floating box floats, and absorbs the energy generated by the impact on the floating cylinder.

2. The cylinder device for a Stirling refrigerator according to claim 1, wherein: The flexible connecting piece includes a corrugated section with a trough, the corrugated section is made of metal material, and the wall thickness of the corrugated section is 0.15mm to 0.25mm.

3. The cylinder device for a Stirling refrigerator according to claim 2, wherein: The corrugated section has a triangular wave shape, and the surfaces of two adjacent sides of the trough on the corrugated section intersect to form a trough angle, and the trough angle is 50° to 60°.

4. The cylinder device for a Stirling refrigerator according to claim 2 or 3, characterized in that: The corrugated section is formed by connecting a first ring section and a second ring section that are bendable in the middle, and the trough is formed at the connection between the two ring sections; The end of the first ring segment away from the trough is a first fixed end and is fixed to the floating cylinder body, and the end of the second ring segment away from the trough is a second fixed end and is fixed to the end cover. The height difference between the first fixed end and the trough is not greater than the height difference between the second fixed end and the trough.

5. The cylinder device for a Stirling refrigerator according to claim 4, wherein: The flexible connector also includes: a first connecting section, one end surface of which is connected to the first fixed end, and the other end surface of which is in close contact with the end surface of the floating cylinder, wherein the first fixed end is fixed to the floating cylinder through the first connecting section; When the flexible connector is in an undeformed initial state, the first connecting segment is perpendicular to the central axis of the corrugated segment, and the angle between the first connecting segment and the first ring segment is 25° to 30°.

6. The cylinder device for a Stirling refrigerator according to any one of claims 1 to 3, characterized in that: The compression chamber is defined by the inner wall of the floating cylinder, the piston end face, the flexible connector and the end cover; An air flow channel is formed on the end cover, one end of the air flow channel is communicated with the compression chamber, and the other end passes through the end cover and is communicated with the expansion chamber of the expander.

7. The cylinder device for a Stirling refrigerator according to any one of claims 1 to 3, characterized in that: A first installation cavity is formed in the installation box, and the floating cylinder is installed in the first installation cavity with a buffer member provided therebetween; When the floating cylinder floats and presses the buffer member, the buffer member can buffer and absorb energy of the floating cylinder.

8. The cylinder device for a Stirling refrigerator according to claim 7, wherein: The buffer is annular and is arranged on the floating cylinder along the circumference of the floating cylinder; The outer annular surface of the buffer component is loosely matched with the inner wall of the first installation cavity.

9. The cylinder device for a Stirling refrigerator according to claim 8, wherein: An installation groove is circumferentially provided on the outer wall of the floating cylinder body. The buffer component is embedded in the installation groove, and the inner annular surface of the buffer component is interference-fitted with the inner bottom wall of the installation groove.

10. The cylinder device for a Stirling refrigerator according to any one of claims 1 to 3, characterized in that: The driving mechanism is a crank-connecting rod mechanism, including a crankshaft, a crank and a transmission rod, wherein the crankshaft is rotatably arranged on the mounting box; the crankshaft is drivingly connected to the motor, and the crankshaft is fixed to the crank; One end of the transmission rod is rotationally connected to the crank, and the other end of the transmission rod is rotationally connected to the piston.

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