A piston assembly of a linear compressor and an assembly method thereof

Abstract

The present invention relates to a piston assembly of a linear compressor and an assembly method thereof. A valve plate assembly and an air inlet are arranged at the bottom end of a compressed air flotation lower liner, and a microgroove is arranged on one side of the bottom end of the piston upper liner, so that the airflow entering the hollow cavity of the compressed air flotation lower liner can flow to the annular gap through the microgroove; a vertical flow channel and a radial flow channel are arranged at the other side of the compressed air flotation lower liner and the corresponding position on the same side of the piston upper liner, a plurality of porous medium particles connected to the annular gap are arranged in the vertical flow channel, and one or more porous medium particles are arranged in the radial flow channel to form a primary throttling, and the radial flow channel is located between two first sealing rings; at least one row of throttling structures are arranged on the surface of the compression piston along the circumferential direction, and the throttling structures include microgroove 1 and microgroove 2 arranged on the outer periphery of the compressed air flotation lower liner, and through holes arranged on the compression piston, the number of which is greater than or equal to 2, and the airflow is discharged outward through microgroove 1, microgroove 2 and through holes in sequence to form a secondary throttling.

Description

Technical Field

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

[0002] Linear compressors are mainly driven by linear motors to make the piston perform linear reciprocating motion in the cylinder to compress the refrigerant. Since the piston operates at a high frequency and adopts an integral welded sealed oil-free operation mode, lubricants are not allowed to be added when the piston operates in the cylinder. Friction and wear between the piston and the cylinder seriously affect the refrigeration performance and service life of the cryogenic refrigerator. At present, in response to the requirements of compact design of cryogenic refrigerators, static pressure gas bearings are generally used to support the piston components.

[0003] The piston supported by the gas bearing mainly uses the pressure generated by the piston movement to compress the working gas to form high-pressure gas. The high-pressure gas then enters the annular gap between the piston and the cylinder from multiple points around the piston after being throttled by the "throttle", forming a stable gas film and giving the piston radial support. At present, the gas bearing throttle has porous plastic belts, small holes, etc. These technologies and structures have problems such as poor stability, high processing difficulty, and high piston manufacturing cost.

[0004] For example, a Chinese patent document with a publication date of 2022.03.08 and a publication number of CN215983307U discloses a piston for a Stirling refrigerator, wherein the power piston includes a power piston body, an inner liner, a fixed pressure plate, a guide sleeve, etc. Its working principle is: the gas enters the first air inlet through the piston body and the gas channel in the inner liner through the first one-way air inlet device and extends to the first air reservoir. Then it passes through the primary throttling device and the first throttling device to reach the gap between the piston and the cylinder. It has the following problems:

[0005] 1) Complex structure and process, long production time: The power piston liner is divided into several sections along its axial direction, and the sections are connected by threads. The first throttling device on the piston body and the first-level throttling device on the liner have the same structure, both of which are cylindrical hexagon socket screws. Therefore, the overall parts processing technology of the structure is complex, the assembly inspection time between the liner and the piston is long, and the efficiency is low.

[0006] 2) The throttle is prone to clogging: The throttling device is inlaid with screws, and uses processes such as sandblasting, corrosion or wire drawing. The structure and process are complex, which may easily cause clogging of the throttling device during actual use.

[0007] 3) The consistency of the throttle is difficult to control, the detection cost is high, and the consistency is poor, which affects the reliability of the piston air float pressure and shortens the operating life of the refrigerator. Summary of the invention

[0008] The present invention aims to provide a piston assembly of a linear compressor to solve the above technical problems.

[0009] The present invention adopts the following technical solutions:

[0010] A piston assembly of a linear compressor comprises a cover plate 1, an upper piston liner 2, a compressed air flotation lower liner 3, and a compression piston 4; the compression piston 4 is hollow inside and is provided with a compressed air flotation lower liner 3 and an upper piston liner 2; the compressed air flotation lower liner 3 is fixedly connected to the compression piston 4, the lower end surface of the upper piston liner 2 is close to the upper end of the compressed air flotation lower liner 3, and the upper end surface is fixedly connected to the cover plate 1; two first sealing rings 15 are arranged between the compressed air flotation lower liner 3 and the compression piston 4 through an annular sealing groove, so two first sealing rings 15 are also arranged between the upper piston liner 2 and the compression piston 4 through an annular sealing groove, which are used to prevent the working medium gas from flowing through the annular gap between the compression piston 4 and the liner; the compressed air flotation lower liner 3 is provided with a valve plate assembly and an air inlet 6 at the bottom end, and a micro groove 12 is arranged on one side of the bottom end of the upper piston liner 2, which can allow the gas to enter The airflow in the hollow cavity of the compressed air flotation liner 3 flows to the annular gap through the microgroove 12; a vertical flow channel and a radial flow channel are respectively arranged at the other side of the compressed air flotation liner 3 and the corresponding position on the same side of the piston upper liner 2, and a plurality of porous medium particles connected to the annular gap are installed in the vertical flow channel, and one or more porous medium particles are installed in the radial flow channel to form a primary throttling, and the radial flow channel is located between the two first sealing rings 15; at least one row of throttling structures are arranged along the circumferential direction on the surface of the compression piston 4, and the throttling structure includes microgroove 1 and microgroove 2 arranged on the outer periphery of the compressed air flotation liner 3, and through holes arranged on the compression piston 4, the number of the through holes is greater than or equal to 2, and the microgroove 1 partially overlaps with the radial flow channel, and the airflow is discharged outward through microgroove 1, microgroove 2 and the through hole in turn to form a secondary throttling.

[0011] Preferably, the bottom end of the compressed air flotation lower liner 3 is connected to the compression piston 4 by screws; and the upper end surface of the piston upper liner 2 is fixedly connected to the cover plate 1 by screws.

[0012] Preferably, there is a micro groove three 13 at the connection between the compressed air flotation lower liner 3 and the compression piston 4, and the micro groove three 13 can exhaust air to the outside through the screw gap.

[0013] Preferably, the valve plate assembly includes a one-way valve plate 9 and a valve plate seat 10, the one-way valve plate 9 and the valve plate seat 10 are welded to form a valve plate assembly, and the valve plate assembly is connected to the bottom end of the compressed air flotation liner 3 by screws.

[0014] Preferably, the volume of microgroove 1 is larger than that of microgroove 2.

[0015] Furthermore, the outer end of the through hole on the compression piston 4 has an enlarged end structure.

[0016] Preferably, an O-ring 8 is sleeved inside the air inlet 6 to buffer pressure shocks, and a small section of small holes is provided below the O-ring 8 for drainage, and a filter mesh 7 made of multiple layers of stainless steel wire is filled below the small holes to filter foreign matter.

[0017] Furthermore, the air inlet 6 is plugged by a set screw 11 to prevent the filter mesh from falling. The set screw 11 is a hollow screw with a hollow diameter in the range of 0.08mm to 2mm. The air intake volume is adjusted by changing the diameter of the hollow screw, thereby adjusting the air flotation flow rate.

[0018] A working method of a piston assembly of a linear compressor. When a static pressure gas bearing is working, it absorbs high-pressure gas during compression of a refrigerator. The high-pressure gas passes through an air inlet hole 6 at the bottom end of a compressed air flotation lower liner 3, pushes open a valve plate assembly, and enters the inner cavity of the compressed air flotation lower liner 3. Then, the gas flows evenly into an annular flow channel between the upper and lower liners of the piston and a compression piston 4 through microgrooves 12 above the compressed air flotation lower liner 3, and then passes through multiple vertical and radial porous medium particles of an upper liner 2 of the piston and a compressed air flotation lower liner 3, and then enters the through hole on the compression piston 4 body through microgrooves 1 and 2. Through its throttling effect, a stable air film is formed in the gap between the piston and the cylinder wall to provide the radial support force required by the piston and reduce the friction between the piston and the cylinder.

[0019] A method for assembling a piston assembly of a linear compressor,

[0020] S1: First, the one-way valve plate 9 and the valve plate seat 10 are welded to form a valve plate assembly;

[0021] S2: Place the upper end surface of the piston liner 2 horizontally on the table, and fill the vertical flow channel with one or more porous medium particles; the radial flow channel is filled with one or more porous medium particles. Put two sealing rings on the sealing groove on the side of the piston liner 2;

[0022] S3: Place a single or multi-layer filter mesh 7 at one end of the compressed air flotation liner 3 with the air inlet hole, and then tighten it with a set screw 11 below the filter mesh. Place the bottom end of the compressed air flotation liner 3 horizontally on the table, and place an O-ring 8 on the small hole above the air inlet hole; connect the welded valve plate assembly to the bottom end of the compressed air flotation liner 3 with screws; then use two O-rings to cover the sealing groove on the side of the compressed air flotation liner 3; install a single or multiple porous medium particles in the vertical flow channel on the side of the compressed air flotation liner 3; install a single or multiple porous medium particles in the radial flow channel;

[0023] S4: Insert the bottom end of the compressed air flotation liner 3 into the inner hollow of the compression piston 4 near the throttle end. Connect the bottom boss of the compressed air flotation liner 3 and the compression piston 4 with screws; install the piston upper liner 2 installed in step 2 into the other end of the compression piston 4, with its lower end surface close to the upper end of the compressed air flotation liner 3;

[0024] S5: Connect the upper end surface of the piston upper liner 2 to the cover plate 1 by means of screws.

[0025] The beneficial effects of the present invention are:

[0026] 1) The compression piston body and the liner of the piston assembly adopt a split structure, and the liner sections also adopt a split structure. The piston liner sections are connected by sliding to avoid thread slippage when the connecting rod is threaded.

[0027] 2) 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 ring grooves and drilling processes.

[0028] 3) The invention has a simple structure, is easy to process, and is easy to install, disassemble and replace; 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. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a cross-sectional view of a piston assembly of a linear compressor of the present invention.

[0030] Figure 2 yes Figure 1 Magnified image of the lower right part of .

[0031] Figure 3 yes Figure 2 A partial enlarged view of .

[0032] Figure 4 It is a cross-sectional view of the piston assembly of the linear compressor of the present invention at another angle.

[0033] Figure 5 yes Figure 4 A partial enlarged view of .

[0034] Figure 6 yes Figure 4 Another partial enlargement of .

[0035] Among them, 1. cover plate, 2. piston upper lining, 3. compressed air flotation lower lining, 4. compression piston, 6. air inlet, 7. filter mesh, 8. O-ring, 9. one-way valve plate, 10. valve plate seat, 11. set screw, 12. micro groove, 13. micro groove three, 14. throttle, 15. first sealing ring. DETAILED DESCRIPTION

[0036] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments.

[0037] See also Figure 1-4 The entire piston assembly is mainly composed of a cover plate 1, a piston upper liner 2, a compressed air flotation lower liner 3, and a compression piston 4.

[0038] The compression piston 4 is hollow inside, and the hollow inside is provided with a compressed air flotation lower liner 3 and a piston upper liner 2. The bottom end of the compressed air flotation lower liner 3 is connected to the compression piston 4 by screws. The piston upper liner 2 is installed inside the compression piston 4, and its lower end face is close to the upper end of the compressed air flotation lower liner 3, and the upper end face is connected to the cover plate 1 by screws.

[0039] The compression piston adopts a split structure consisting of a compression piston body and an inner liner, and the piston inner liner can be directly processed using formed pipes and molded parts, and the processing methods are not limited to lathes and milling machines; it is convenient to process the internal ring grooves and design micro grooves, flow channels and other processes, thereby facilitating the formation of an air reservoir, with a better sealing effect, and the other parts of the piston are also easy to process. The inner liner is also a split structure, which is convenient for replacement and installation.

[0040] See also Figure 1-2 The compressed air flotation liner 3 is provided with a valve plate assembly and an air inlet 6 at the bottom. Two annular sealing grooves, multiple annular microgrooves, and vertical flow channels and radial flow channels are provided on the left side. An O-ring is installed in the annular sealing groove, which can effectively prevent the working gas from flowing from the annular gap between the compression piston and the liner. Two porous medium particles are installed in the vertical flow channel; one porous medium particle is installed in the radial flow channel. The annular microgrooves are used to adjust the shape of the airflow.

[0041] Continue to see Figure 1-2 The valve plate assembly includes a one-way valve plate 9 and a valve plate seat 10. The one-way valve plate 9 and the valve plate seat 10 are welded to form a valve plate assembly, and the valve plate assembly is connected to the bottom end of the compressed air flotation liner 3 by screws. In this way, the valve plate assembly can be close to the compressed air flotation liner 3 to maintain a small roughness; the internal high-pressure chamber can be kept at a small leakage. If the valve plate is directly fixed on the compressed air flotation liner 3, it is impossible to determine whether the valve plate fits the compressed air flotation liner 3. Furthermore, the use of this valve plate assembly can effectively reduce costs and processing difficulty; it is easy to replace and easy to detect.

[0042] See also Figure 2 , an O-ring 8 is sleeved inside the air inlet 6 to buffer the pressure shock. A small section of small holes is set below the O-ring 8 for drainage. A filter mesh 7 made of multiple layers of stainless steel wire is filled under the small hole to filter foreign matter. Then the air inlet is plugged with a set screw 11 to prevent the filter mesh from falling. The set screw 11 is an M3 hollow screw with a diameter in the range of 0.3mm~2mm, so the air intake can be adjusted by changing the diameter, thereby adjusting the air flotation flow rate.

[0043] See also Figure 1 and Figure 4 The side of the piston upper liner 2 is provided with two sealing rings, a plurality of annular microgrooves, and a vertical flow channel and a radial flow channel on the left side. Two porous medium particles are installed in the vertical flow channel; one porous medium particle is installed in the radial flow channel. A microgroove 12 is provided on the right side of the bottom end, so that the airflow can flow to the annular gap through the microgroove.

[0044] At least one row of throttling structures is arranged on the surface of the compression piston 4 along the circumferential direction, each row includes at least two throttling structures, and all throttling devices in the same row are evenly distributed along the circumferential direction; the size, position, number, type (not limited to small hole throttling) and processing technology of the throttling device can be changed according to actual needs.

[0045] Figure 5 and Figure 6 for Figure 4 A partial enlarged view of two symmetrical positions in the Figure 5 It is located in the middle right position. Figure 4 It is located on the left side of the middle. Figure 6 to explain.

[0046] See Figure 6 The throttling structure includes microgrooves 1 and 2 arranged on the outer periphery of the liner 3 under the compressed air flotation, and a through hole arranged on the compression piston 4. The microgrooves 1 partially overlap with the radial flow channel, and the airflow is discharged outward through the microgrooves 1, 2 and the through hole in sequence, forming a second throttling. The throttle 14 of the present invention is a through hole, which has low overall processing difficulty and no clogging phenomenon. It avoids the defects of easy clogging of the micropores of the traditional air flotation structure and the small pores of the porous medium, and can provide a stable air film for the piston and the cylinder, reduce friction, and improve reliability.

[0047] See also Figure 2 There is a micro groove 3 13 at the connection between the compressed air flotation liner 3 and the compression piston 4, and the micro groove can exhaust air outward through the screw gap.

[0048] When the static pressure gas bearing is working, it absorbs the high-pressure gas during the compression of the refrigerator. The high-pressure gas passes through the air inlet hole 6 at the bottom end of the compressed air flotation liner 3, enters the hollow area of ​​the set screw 11, flows through the filter mesh 7, pushes open the valve plate assembly, and enters the compressed air flotation liner 3. Then the gas flows evenly into the annular flow channel between the upper and lower liners of the piston and the compression piston 4 through the micro grooves 12 above the compressed air flotation liner 3, and then enters the throttling hole of the compression piston 4 through the porous medium particles of the piston upper liner 2 and the compressed air flotation liner 3. After its throttling effect, a stable air film is formed in the gap between the piston and the cylinder wall to provide the radial support force required by the piston and reduce the friction between the piston and the cylinder.

[0049] The gas enters the piston liner cavity through the one-way valve plate. During the operation of the piston, the gas inside the cavity flows out through the ring groove flow channel and the throttle to the gap between the compression piston and the cylinder, forming a uniform air film, that is, an air bearing structure. The compression piston is a cylindrical structure with simple processing. It can be processed by mold opening, profiles, etc., and it is highly replaceable. The piston liner and the compression piston body adopt a split structure with a simple internal structure, easy disassembly, and low cost. The piston liner can be directly processed using formed pipes and mold parts. The processing methods are not limited to lathes, milling machines, etc.; it is also convenient for processing ring grooves and drilling processes.

[0050] The assembly method of the piston assembly of the linear compressor comprises the following steps:

[0051] Step 1: First, the one-way valve plate 9 and the valve plate seat 10 are welded to form a valve plate assembly.

[0052] Step 2: Place the upper end surface of the piston liner 2 horizontally on the table, and fill the vertical flow channel with one or more porous medium particles; the radial flow channel with one or more porous medium particles. Put two sealing rings on the sealing groove on the side of the piston liner 2.

[0053] Step 3: Place multiple layers of filter mesh 7 at one end of the compressed air flotation liner 3 with the air inlet hole, and then tighten the filter mesh with the set screws 11. Place the bottom end of the compressed air flotation liner 3 horizontally on the table, and place an O-ring 8 on the small hole above the air inlet hole. Connect the welded valve plate assembly to the bottom end of the compressed air flotation liner 3 with screws. Then use two O-rings to cover the sealing groove on the side of the compressed air flotation liner 3. Install a single or multiple porous medium particles in the vertical flow channel on the side of the compressed air flotation liner 3; install a single or multiple porous medium particles in the radial flow channel. The porous medium particles are not limited to metal or non-metal materials and certain shapes.

[0054] Step 4: Insert the bottom end of the compressed air flotation liner 3 into the internal hollow space near the end of the compression piston 4 near the throttle. Use screws to connect the bottom boss of the compressed air flotation liner 3 and the compression piston 4. Install the piston upper liner 2 installed in step 2 into the other end of the compression piston 4, with its lower end surface close to the upper end of the compressed air flotation liner 3.

[0055] Step 5: Connect the upper end surface of the piston upper liner 2 to the cover plate 1 through screws.

[0056] The compression piston adopts a split structure consisting of a compression piston body and an inner liner, and the piston inner liner can be directly processed using formed pipes and molded parts, and the processing methods are not limited to lathes and milling machines; it is convenient to process the internal ring grooves and design micro grooves, flow channels and other processes, thereby facilitating the formation of an air reservoir, with a better sealing effect, and the other parts of the piston are also easy to process. The inner liner is also a split structure, which is convenient for replacement and installation.

[0057] The above are preferred embodiments of the present invention. Those skilled in the art may also make respective changes or improvements thereon. Without departing from the general concept of the present invention, these changes or improvements shall fall within the scope of protection claimed by the present invention.

Claims

1. A piston assembly of a linear compressor, characterized in that: It comprises a cover plate (1), a piston upper liner (2), a compressed air flotation lower liner (3), and a compression piston (4); The compression piston (4) is hollow inside and is provided with a compressed air flotation lower liner (3) and a piston upper liner (2); the compressed air flotation lower liner (3) is fixedly connected to the compression piston (4), the lower end surface of the piston upper liner (2) is closely adjacent to the upper end of the compressed air flotation lower liner (3), and the upper end surface is fixedly connected to the cover plate (1); Two first sealing rings (15) are arranged between the compressed gas floating lower liner (3) and the compression piston (4) via an annular sealing groove, so two first sealing rings (15) are also arranged between the piston upper liner (2) and the compression piston (4) via an annular sealing groove, so as to prevent the working medium gas from flowing through the annular gap between the compression piston (4) and the liner; The compressed air flotation lower liner (3) is provided with a valve plate assembly and an air inlet hole (6) at the bottom end, and a micro groove (12) is provided on one side of the bottom end of the piston upper liner (2), so that the airflow entering the hollow cavity of the compressed air flotation lower liner (3) can flow to the annular gap through the micro groove (12); A vertical flow channel and a radial flow channel are respectively arranged at the other side of the compressed air flotation lower liner (3) and at the same side of the corresponding piston upper liner (2), wherein a plurality of porous media connected to the annular gap are arranged in the vertical flow channel, and one or more porous media are arranged in the radial flow channel to form a primary throttling, wherein the radial flow channel is located between two first sealing rings (15); At least one row of throttling structures is arranged on the surface of the compression piston (4) along the circumferential direction. The throttling structure comprises microgrooves 1 and 2 arranged on the outer periphery of the liner (3) under the compression air flotation, and through holes arranged on the compression piston (4). The number of the through holes is greater than or equal to 2. 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 outward, forming a second throttling.

2. The piston assembly of the linear compressor according to claim 1, characterized in that: The bottom end of the compressed air floating lower liner (3) is connected to the compression piston (4) via screws; and the upper end surface of the piston upper liner (2) is fixedly connected to the cover plate (1) via screws.

3. The piston assembly of the linear compressor according to claim 1, characterized in that: There is a micro groove three (13) at the connection between the compressed air flotation lower liner (3) and the compression piston (4), and the micro groove three (13) can exhaust air to the outside through the screw gap.

4. The piston assembly of the linear compressor according to claim 1, characterized in that: The valve plate assembly comprises a one-way valve plate (9) and a valve plate seat (10); the one-way valve plate (9) and the valve plate seat (10) are welded together to form the valve plate assembly; and the valve plate assembly is connected to the bottom end of the compressed air flotation liner (3) by screws.

5. The piston assembly of the linear compressor according to claim 1, characterized in that: The volume of the micro groove 1 is larger than that of the micro groove 2.

6. The piston assembly of the linear compressor according to claim 5, characterized in that: The outer end of the through hole on the compression piston (4) has an enlarged end structure.

7. The piston assembly of a linear compressor according to claim 1, characterized in that: An O-ring (8) is sleeved inside the air inlet (6) to buffer pressure shocks. A small section of small holes is provided below the O-ring (8) for drainage. Multiple layers of filter mesh (7) are filled below the small holes to filter foreign matter.

8. The piston assembly of the linear compressor according to claim 7, characterized in that: The air inlet hole (6) is plugged by a set screw (11) to prevent the filter mesh from falling off. The set screw (11) is a hollow screw with a diameter in the range of 0.08 mm to 2 mm. The air intake volume is adjusted by changing the diameter of the hollow screw, thereby adjusting the air flotation flow rate.

9. A method for operating a piston assembly of a linear compressor according to any one of claims 1 to 8, characterized in that: When the static pressure gas bearing is working, it absorbs the high-pressure gas during the compression of the refrigerator. The high-pressure gas passes through the air inlet hole (6) at the bottom end of the compressed air flotation lower liner (3), pushes open the valve plate assembly, and enters the inner cavity of the compressed air flotation lower liner (3). Then, the gas flows evenly into the annular flow channel between the upper and lower liners of the piston and the compression piston (4) through the micro grooves (12) above the compressed air flotation lower liner (3), and then passes through the multiple vertical and radial porous medium particles of the piston upper liner (2) and the compressed air flotation lower liner (3), and then enters the through hole on the compression piston (4) body through micro grooves 1 and 2. After the throttling effect, a stable gas film is formed in the gap between the piston and the cylinder wall to provide the radial support force required by the piston and reduce the friction between the piston and the cylinder.

10. A method for assembling a piston assembly of a linear compressor according to any one of claims 1 to 8, characterized in that: S1: First, the one-way valve plate (9) and the valve plate seat (10) are welded to form a valve plate assembly; S2: Place the upper end surface of the piston upper liner (2) horizontally on a table, and load a single or multiple porous medium particles into the vertical flow channel; load one or more porous medium objects into the radial flow channel; and put two sealing rings on the sealing groove on the side of the piston upper liner (2); S3: Place a single or multi-layer filter mesh (7) at one end of the compressed air flotation liner (3) with an air inlet hole, and then tighten the filter mesh using a set screw (11); place the bottom end of the compressed air flotation liner (3) horizontally on a table, and place an O-ring (8) on the small hole above the air inlet hole; connect the welded valve plate assembly to the bottom end of the compressed air flotation liner (3) with screws; then use two O-rings to cover the sealing groove on the side of the compressed air flotation liner (3); install a single or multiple porous medium particles in the vertical flow channel on the side of the compressed air flotation liner (3); install a single or multiple porous medium particles in the radial flow channel; S4: Insert the bottom end of the compressed air flotation liner (3) into the internal hollow space of the compression piston (4) near the throttle end; connect the bottom end boss of the compressed air flotation liner (3) and the compression piston (4) with screws; install the piston upper liner (2) installed in step 2 into the other end of the compression piston (4), with its lower end surface close to the upper end of the compressed air flotation liner (3); S5: Connect the upper end surface of the piston upper liner (2) to the cover plate (1) by means of screws.

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