Compressor piston assembly for Stirling cryocooler and assembling method of compressor piston assembly

Abstract

The compressor piston assembly is characterized in that a small guide air cylinder is adhered to a central coaxial hole of an upper lining of a piston, and a small air inlet hole is formed in the upper surface of the upper lining of the piston; the valve plate component is installed on the lower surface of the upper lining of the piston through a screw and is aligned with the small air inlet hole, and air enters the valve plate component from the small air inlet hole and then enters the compression piston. A flange structure is arranged on the periphery of the piston upper lining, the flange structure is connected with the compression piston through an upper lining screw, and the piston lower lining is arranged in the compression piston and attached to the piston upper lining. The cover plate is provided with a shaft part and a disc part, and the shaft part covers the lower surface of the piston lower lining; the disc part covers the lower end surface of the magnetic steel bracket and is fixedly connected with the magnetic steel bracket through a magnetic steel screw; the magnetic steel support and the magnetic steel are sleeved with the thin-wall sleeve part, the lower portion of the thin-wall sleeve part is fixedly welded to the magnetic steel support, the magnetic shoe welding ring is welded to the inner side of the upper portion of the thin-wall sleeve part and abuts against the upper end of the magnetic steel, and if the magnetic steel needs to be detached, only the thin-wall sleeve part needs to be turned off, and replacement is easy.

Description

Technical Field

[0001] The invention relates to a refrigeration device, in particular to a compressor piston assembly for a Stirling refrigerator and an assembly method thereof, belonging to the technical field of low-temperature refrigeration. Background Art

[0002] In order to meet the requirements of long life and high reliability, Stirling refrigerators usually use an air bearing structure to ensure that the piston and the cylinder maintain a gap seal and do not directly contact. This design enables the piston to always remain in a suspended state when moving in the cylinder.

[0003] As disclosed on March 8, 2022, a Chinese patent document with a publication number of CN215983307U discloses a piston for a Stirling refrigerator, whose power piston contains an inner lining and a first air reservoir, and is equipped with a first air inlet, a first one-way air inlet device, and a first throttling device. Its working principle is: through the first air inlet on the power piston, the gas enters the first air reservoir inside. During the air intake process, the first one-way air inlet device allows the gas to enter the air reservoir in one direction to prevent backflow. When the piston slides back and forth, the gas in the first air reservoir is compressed and flows out to the outside of the piston through the first throttling device to form an air film, and the air film forms an air-floating bearing structure.

[0004] The existing problems are: the power piston lining adopts a multi-section structure, and the sections are connected by screws, which makes the structure complicated, difficult to assemble, and inconvenient to disassemble. It is difficult to independently replace and reuse each component during maintenance; the throttling device is inlaid with screws and uses sandblasting, corrosion or wire drawing processing. The structure and process are complicated, and the throttling device is easily blocked during actual use; multiple throttling porous media devices increase the cost and complexity of assembly. Summary of the invention

[0005] In order to solve the above problems, the present invention provides a compression piston assembly of a Stirling refrigerator, in which the upper liner and the lower liner of the piston are fitted together without screw connection, thereby reducing the complexity of assembly and facilitating disassembly, and each component can be independently replaced and reused during maintenance; when the piston takes in air, it is filtered by the air inlet filter mesh (to prevent clogging of the porous medium and the small air outlet holes) and then enters the piston cavity through a one-way valve, and after throttling the porous medium once to form a uniform gas film, it is throttled through the small holes to form a uniform air film, that is, an air floating bearing structure. Compared with the throttling device, the throttling gas outlet is more uniform, the flow consistency is good, the cost is low, the assembly yield is high, and the time is short; and due to the design of the air floating bearing structure, structural interference between the compression piston and the liner during assembly is avoided, thereby realizing a structure in which each component can be independently disassembled.

[0006] The present invention adopts the following technical solutions:

[0007] A compressor piston assembly for a Stirling refrigerator comprises a piston lower liner 1, a guide small cylinder 2, a valve plate component, a compression piston 5, a piston lower liner 6, a cover plate 7, a magnetic steel 8, a magnetic tile welding ring 9, a magnetic steel bracket 10, and a thin-walled sleeve component; the guide small cylinder 2 is glued to the central coaxial hole of the piston upper liner 1, and an air intake hole is processed on the upper surface of the piston upper liner 1; the valve plate component is installed on the lower surface of the piston upper liner 1 by an air intake screw and is aligned with the air intake hole. After the gas enters from the air intake hole, the valve plate component enters the compression piston 5, and the valve plate component acts as a one-way valve; the piston upper liner 1 is surrounded by a flange Structure, the flange structure is connected to the compression piston 5 through the upper lining screws, the piston lower lining 6 is installed in the compression piston 5, and fits with the piston upper lining 1; the cover plate 7 has a shaft portion and a disk portion, the shaft portion covers the lower surface of the piston lower lining 6; the disk portion covers the lower end surface of the magnetic steel bracket 10 and is fixedly connected to the magnetic steel bracket 10 through the magnetic steel screws; the thin-walled sleeve member 11 is sleeved on the outside of the magnetic steel bracket 10 and the magnetic steel 8, and its lower part is welded and fixed to the magnetic steel bracket 10, and a magnetic tile welding ring 9 is welded on the inner side of the upper part, and the magnetic tile welding ring 9 is against the upper end of the magnetic steel 8. If the magnetic steel 8 needs to be disassembled, the thin-walled sleeve member is turned off.

[0008] Preferably, two first sealing rings are arranged between the upper piston liner 1 and the compression piston 5 through an annular sealing groove, so two first sealing rings are also arranged between the lower piston liner 6 and the compression piston 5 through an annular sealing groove, which are used to prevent the working medium gas from flowing from the annular gap between the compression piston 5 and the liner; a vertical flow channel and a radial flow channel are respectively arranged on the upper piston liner 1 and the lower piston liner 6, and a plurality of porous medium particles connected to the annular gap are installed in the vertical flow channel, and a porous medium particle is installed in the radial flow channel to form a primary throttling, and the radial flow channel is located between the two first sealing rings; at least one row of throttling structures are arranged on the surface of the compression piston 5 along the circumferential direction, and the throttling structure includes microgroove 1 and microgroove 2 arranged on the outer periphery of the upper piston liner 1 and the lower piston liner 6, and a through hole arranged on the compression piston 5, the microgroove 1 partially overlaps with the radial flow channel, and the airflow passes through the microgroove 1, the microgroove 2 and the through hole in turn and is discharged to the outside of the compression piston 5, forming a secondary throttling.

[0009] Preferably, a filter mesh is provided in the air inlet hole, and the filter mesh is fixed with screws above. The screws can control the air intake and adjust the air flotation flow rate.

[0010] Preferably, the valve plate component includes a valve plate seat 3 and a valve plate 4 .

[0011] Furthermore, an annular sealing groove is also provided on the outer periphery of the lower end of the piston lower liner 6, and a second sealing ring is provided in the annular sealing groove.

[0012] A method for assembling a compressor piston assembly for a Stirling refrigerator comprises the following steps:

[0013] S1: glue the guide small cylinder 2 and the piston upper liner 1 together, install a filter mesh and fixing screws on the air inlet hole on the upper surface of the piston upper liner 1, install porous media in the lower surface and side holes of the piston upper liner 1 by gluing, put O-rings in the grooves of the upper and lower annular sealing grooves of the piston upper liner 1, and then connect the valve seat 3 and the valve plate 4 in the valve plate component to the piston upper liner 1 by screws. The valve plate component is close to the lower surface of the piston upper liner 1. When gas enters through the small holes on the upper surface of the piston upper liner 1, the valve plate 4 is pushed open, and the valve plate component acts as a one-way valve;

[0014] S2: Connect the piston upper liner 1 and the compression piston 5 with screws;

[0015] S3: The upper surface and side holes of the piston lower liner 6 are filled with porous media by gluing, and the upper, middle and lower grooves of the piston lower liner 6 are placed with O-rings. Then, the piston lower liner 6 is placed in the compression piston 5 and fits with the piston upper liner 1.

[0016] S4: Cover the cover plate 7 on the lower surface of the piston lower liner 6;

[0017] S5: Weld the magnetic shoe welding ring 9 to the upper part of the inner side of the thin-walled sleeve part 11, and the thin-walled sleeve part 11 is sleeved on the outside of the piston lower liner 6 and the magnetic steel 8, so that the magnetic shoe welding ring 9 is against the upper end of the magnetic steel 8, and the thin-walled sleeve part 11 and the magnetic steel 8 are welded and fixed; then the magnetic steel 8 and the cover plate 7 are connected with screws.

[0018] Preferably, when the magnetic steel 8 or the magnetic steel bracket 10 needs to be removed, the thin-walled sleeve member 11 is cut off.

[0019] The beneficial effects of the present invention are:

[0020] 1) Simplified structure, reduced cost, easy processing, easy installation and disassembly and replacement: Adopt split module fitting structure (such as upper liner, lower liner), easy to assemble and disassemble (magnetic steel, magnetic steel bracket, guide small cylinder, upper and lower liner of piston can be easily disassembled and replaced separately during repair and maintenance, which greatly reduces maintenance costs);

[0021] 2) Through the throttling design of porous media and small holes, uniform airflow and precise air output control are achieved, which improves the stability of air flotation performance and reduces costs. It can effectively simplify the inspection process, reduce production time and manufacturing costs, improve assembly efficiency, ensure workpiece consistency, and is suitable for mass production. At the same time, the throttle is a through hole, the overall processing difficulty is small, and there is no clogging phenomenon, which avoids the defects of easy clogging of small holes in traditional air flotation structures and small holes in porous media. It can provide a stable air film for the piston and cylinder, reduce friction, and improve reliability.

[0022] 3) The piston liner can be directly processed using formed pipes and open mold parts, and the processing methods are not limited to lathes, milling machines, etc.; it is also convenient for processing processes such as ring grooves and drilling.

[0023] 4) Filtering function: The filter mesh design is added to effectively prevent impurities, metal debris and dust from entering the piston, improving the durability and reliability of the equipment.

[0024] 5) Air intake adjustment: The air intake is controlled by a hollow screw to achieve precise adjustment of the air flotation flow rate, which is more suitable for different working conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a cross-sectional view of the piston assembly of the compressor for Stirling refrigerator of the present invention. After the figure is rotated 180 degrees, it is the form of the actual working state.

[0026] Figure 2 This is another cross-sectional view of the piston assembly of the compressor for Stirling refrigerator of the present invention. After the figure is rotated 180 degrees, it is the actual working state.

[0027] Figure 3 yes Figure 2 The local enlarged image mainly shows the structure of two microgrooves.

[0028] In the figure, 1. piston lower lining, 2. guide small cylinder 2, 3. valve plate seat, 4. valve plate, 5. compression piston, 6. piston lower lining, 7. cover plate, 8. magnetic steel, 9. magnetic tile welding ring, 10. magnetic steel bracket, 11. thin-walled sleeve. DETAILED DESCRIPTION

[0029] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments.

[0030] Figure 1 It is a cross-sectional view of a compression piston assembly for a Stirling refrigerator, which includes: a piston lower liner 1, a guide small cylinder 2, a valve plate seat 3, a valve plate 4, a compression piston 5, a piston lower liner 6, a cover plate 7, a magnetic steel 8, a magnetic tile welding ring 9, a magnetic steel bracket 10, and a thin-walled sleeve 11;

[0031] Figure 2 This is a cross-sectional view of the compression piston assembly for a Stirling refrigerator from a collar angle. It shows the location of the air outlet holes. The air outlet holes are not limited to a row of four holes, and can be freely selected according to the size of the piston.

[0032] See Figure 1-3The guide small cylinder 2 is glued to the central coaxial hole of the piston liner 1. The upper surface of the piston liner 1 is processed with an air intake hole. A filter mesh is installed in the hole to filter magazines, metal debris and dust to prevent them from entering the interior of the piston (the mesh size, thickness and number of filter meshes can be freely selected according to the situation). The mesh is fixed with screws on the top. The screws can control the air intake and adjust the air flotation flow rate; the valve seat 3 and the valve plate 4 together constitute the valve plate component, which is installed on the lower surface of the piston liner 1 by screws. After the gas enters from the air inlet, it opens the valve plate 4 and enters the interior of the piston. The valve plate component acts as a one-way valve;

[0033] The upper and lower grooves of the piston liner 1 are placed with O-rings for sealing. There are two micro grooves in the middle. There is a gap between the micro grooves. The gas that has been throttled once passes through two metal porous media (porous media is not limited to metal porous media) and flows into the large micro groove through the small holes ( Figure 3 After the middle microgroove 1) rectifies the uniform airflow, the gas in this microgroove flows into the small microgroove through the gap and enters the small hole on the surface of the compression piston 2 for secondary throttling ( Figure 3 The second type of microgroove), the small microgroove overlaps half of the small holes on the surface of the compression piston 2, the purpose is to control the gas output (the number of small holes and the number of rows can be freely selected according to the size and length of the piston, and are not limited to four small holes in one row); the piston upper liner 1 is connected to the compression piston 5 by screws, and the piston lower liner 6 is installed in the compression piston 5 and fits with the piston upper liner 1;

[0034] O-rings are placed in the upper, middle and lower grooves of the piston lower liner 6 for sealing. There is a gap between the two middle microgrooves. After the gas passes through two metal porous media (porous media are not limited to metal porous media) and the gas throttled once flows into the large microgroove through the small holes to rectify the uniform airflow, the gas in this microgroove flows into the small microgroove through the gap and enters the small holes on the surface of the compression piston 2 for secondary throttling. Half of the small microgroove overlaps with the small holes on the surface of the compression piston 2, the purpose is to control the gas output (the number of small holes and the number of rows can be freely selected according to the size and length of the piston, and are not limited to four small holes in one row);

[0035] Cover the cover plate 7 on the lower surface of the piston lower liner 6; weld the magnetic tile welding ring 9 to the upper inner side of the thin-walled sleeve 11, and weld the thin-walled sleeve 1 to the magnetic steel bracket 10 at the same time. The magnetic tile welding ring 9 abuts against the upper end of the magnetic steel 8, and the magnetic steel bracket 10 is connected to the cover plate 7 by screws to form a complete compression piston assembly. If the magnetic steel 8 or the magnetic steel bracket 10 needs to be disassembled, it is only necessary to cut the thin-walled sleeve 11.

[0036] The above structure can be easily disassembled, which greatly improves the replaceability of product components and reduces maintenance costs.

[0037] The above-mentioned method for assembling the compression piston assembly for the Stirling refrigerator comprises the following steps:

[0038] Step 1: glue the small guide cylinder 2 to the piston liner 1, install the filter mesh and fixing screws on the air inlet hole on the upper surface of the piston liner 1, install the metal porous medium (porous medium material is not limited to metal) in the lower surface and side holes of the piston liner 1 by gluing process, put the O-ring in the upper and lower grooves of the piston liner 1, and then connect the valve seat 3 and valve plate 4 in the valve plate component to the piston liner 1 by screws. The valve plate component is close to the lower surface of the piston liner 1. When the gas enters through the small holes on the upper surface of the piston liner 1, the valve plate 4 is pushed open, and the valve plate component acts as a one-way valve.

[0039] Step 2: Connect the piston upper liner 1 and the compression piston 5 with screws.

[0040] Step 3: The upper surface and side holes of the piston lower liner 6 are filled with metal porous media (porous media materials are not limited to metals) by gluing, and O-rings are placed in the upper, middle and lower grooves of the piston lower liner 6. Then, the piston lower liner 6 is placed in the compression piston 5 to fit it with the piston upper liner 1.

[0041] Step 4: Cover the cover plate 7 on the lower surface of the piston lower liner 6.

[0042] Step 5: Weld the magnetic tile welding ring 9 to the upper part of the inner side of the thin-walled sleeve 11, and the thin-walled sleeve 11 is sleeved on the outer part of the piston lower liner 6 and the magnetic steel 8, so that the magnetic tile welding ring 9 is against the upper end of the magnetic steel 8, and the thin-walled sleeve 11 and the magnetic steel 8 are welded and fixed; then the magnetic steel 8 and the cover plate 7 are connected with screws. When it is necessary to remove the magnetic steel 8 or the magnetic steel bracket 10, the thin-walled sleeve 11 is cut off.

[0043] The present invention simplifies the structure, reduces the cost, is easy to process, and is easy to install, disassemble and replace: a split module fitting structure (such as an upper liner and a lower liner) is adopted, which is convenient for assembly and disassembly (the magnet, the magnet bracket, the guide small cylinder, and the upper and lower liners of the piston can be easily disassembled and replaced separately during repair and maintenance, which greatly reduces the maintenance cost); through the throttling design of the porous medium and the small hole, uniform airflow and precise air output control are achieved, the stability of the air flotation performance is improved, and the cost is reduced. It can effectively simplify the detection process, reduce the production time and manufacturing cost, improve the assembly efficiency, ensure the consistency of the workpiece, and is suitable for mass production. At the same time, the throttle is a through hole, the overall processing difficulty is small, and no clogging occurs, avoiding the defects of the traditional air flotation structure micropores and porous medium small holes that are easy to clog, and can provide a stable air film for the piston and the cylinder, reduce friction, and improve reliability. The piston liner can be directly processed using formed pipes and open molds, and the processing methods are not limited to lathes, milling machines, etc.; and it is convenient to process ring grooves and punching. Filtering function: The filter mesh design is added to effectively prevent impurities, metal debris and dust from entering the piston, improving the durability and reliability of the equipment. Air intake adjustment: The air intake is controlled by screws to achieve precise adjustment of the air flotation flow rate, which is more suitable for different working conditions.

[0044] The above are preferred embodiments of the present invention. A person skilled in the art may make various changes or improvements on this basis. Without departing from the general concept of the present invention, these changes or improvements should fall within the scope of protection claimed by the present invention.

Claims

1. A compressor piston assembly for a Stirling refrigerator, characterized in that: It comprises a piston lower liner (1), a guide small cylinder (2), a valve plate component, a compression piston (5), a piston lower liner (6), a cover plate (7), a magnetic steel (8), a magnetic tile welding ring (9), a magnetic steel bracket (10), and a thin-walled sleeve component; The guide small cylinder (2) is glued to the central coaxial hole of the piston upper liner (1), and the upper surface of the piston upper liner (1) is processed with an air intake hole; the valve plate component is installed on the lower surface of the piston upper liner (1) by using an air intake screw and is aligned with the air intake hole. After the gas enters the air intake hole, the valve plate component enters the interior of the compression piston (5), and the valve plate component acts as a one-way valve; a flange structure is provided around the piston upper liner (1), and the flange structure is connected to the compression piston (5) through the upper liner screw, and the piston lower liner (6) is installed in the compression piston (5) and fits with the piston upper liner (1); The cover plate (7) comprises a shaft portion and a disk portion, wherein the shaft portion covers the lower surface of the piston lower liner (6); the disk portion covers the lower end surface of the magnetic steel bracket (10) and is fixedly connected to the magnetic steel bracket (10) via magnetic steel screws; The thin-walled sleeve member (11) is sleeved on the outside of the magnetic steel bracket (10) and the magnetic steel (8), and its lower part is welded and fixed to the magnetic steel bracket (10). A magnetic tile welding ring (9) is welded on the inner side of the upper part. The magnetic tile welding ring (9) is against the upper end of the magnetic steel (8). If the magnetic steel (8) needs to be disassembled, the thin-walled sleeve member is cut off by turning.

2. The compressor piston assembly for a Stirling refrigerator according to claim 1, characterized in that: Two first sealing rings are arranged between the upper piston liner (1) and the compression piston (5) via an annular sealing groove, so two first sealing rings are also arranged between the lower piston liner (6) and the compression piston (5) via an annular sealing groove, so as to prevent the working medium gas from flowing through the annular gap between the compression piston (5) and the liner; A vertical flow channel and a radial flow channel are respectively provided on the piston upper liner (1) and the piston lower liner (6), wherein a plurality of porous medium particles communicating with the annular gap are installed in the vertical flow channel, and a porous medium particle is installed in the radial flow channel to form a primary throttling, and the radial flow channel is located between the two first sealing rings; At least one row of throttling structures is arranged on the surface of the compression piston (5) along the circumferential direction. The throttling structures include microgrooves 1 and 2 arranged on the outer peripheries of the piston upper liner (1) and the piston lower liner (6), and through holes arranged on the compression piston (5). The microgrooves 1 partially overlap with the radial flow channel. The airflow passes through the microgrooves 1, 2 and the through holes in sequence and is discharged to the outside of the compression piston (5), thereby forming a second throttling.

3. The compressor piston assembly for a Stirling refrigerator according to claim 1, characterized in that: A filter mesh is arranged in the air inlet hole, and a hollow screw is used to fix the filter mesh. The air intake volume can be controlled and the air flotation flow rate can be adjusted by changing the diameter of the central hole of the hollow screw.

4. The compressor piston assembly for a Stirling refrigerator according to claim 1, characterized in that: The valve plate component comprises a valve plate seat (3) and a valve plate (4).

5. The compressor piston assembly for a Stirling refrigerator according to claim 2, characterized in that: An annular sealing groove is also provided on the outer periphery of the lower end of the piston lower liner (6), and a second sealing ring is provided in the annular sealing groove.

6. A method for assembling a compressor piston assembly for a Stirling refrigerator according to any one of claims 1 to 5, characterized in that: The following steps are involved: S1: The guide small cylinder (2) is glued to the piston upper liner (1), and a filter mesh and a hollow fixing screw are installed on the air inlet hole on the upper surface of the piston upper liner (1). A porous medium is installed in the lower surface and the side hole of the piston upper liner (1) by using a gluing process, and an O-ring is placed in the grooves of the upper and lower annular sealing grooves of the piston upper liner (1). Then, the valve seat (3) and the valve plate (4) in the valve plate component are connected to the piston upper liner (1) by screws. The valve plate component is closely attached to the lower surface of the piston upper liner (1). When gas enters through the small hole on the upper surface of the piston upper liner (1), the valve plate (4) is pushed open, and the valve plate component acts as a one-way valve. S2: Connect the piston upper liner (1) and the compression piston (5) with screws; S3: The upper surface and side holes of the piston lower liner (6) are filled with porous media by gluing, and the upper, middle and lower grooves of the piston lower liner (6) are placed with O-rings. Then, the piston lower liner (6) is placed in the compression piston (5) and fits with the piston upper liner (1); S4: Covering the cover plate (7) on the lower surface of the piston lower liner (6); S5: Weld the magnetic shoe welding ring (9) to the upper part of the inner side of the thin-walled sleeve member (11), and sleeve the thin-walled sleeve member (11) on the outer side of the piston lower liner (6) and the magnetic steel (8), so that the magnetic shoe welding ring (9) abuts against the upper end of the magnetic steel (8), and weld the thin-walled sleeve member (11) and the magnetic steel (8) to fix; then connect the magnetic steel (8) and the cover plate (7) with screws.

7. The method for assembling a compressor piston assembly for a Stirling refrigerator according to claim 6, characterized in that: When the magnetic steel (8) or the magnetic steel bracket (10) needs to be removed, the thin-walled sleeve member (11) is cut off by turning.

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