Air floatation piston structure of free piston thermoacoustic Stirling engine

Abstract

The invention provides a free piston thermoacoustic Stirling air floatation piston structure which comprises an air cylinder internally provided with a mounting cavity. The phase modulator, the power piston and the gas spring piston are all arranged in the mounting cavity, one side of the phase modulator is connected with a Rod rod, and the Rod rod penetrates through the power piston and is connected with the gas spring piston; air gaps are reserved between the gas spring piston and the inner wall of the air cylinder, between the power piston and the inner wall of the air cylinder and between the phase modulator and the inner wall of the air cylinder; a compression cavity is formed between the phase modulator and the power piston; the air supply pipeline is distributed on the inner wall of the air cylinder and corresponds to the axial positions of the phase modulator, the power piston and the gas spring piston, and one end of the air supply pipeline is communicated with the air gap; the other end of the air supply pipeline is communicated with the high-pressure air cavity; and high-pressure gas in the high-pressure gas cavity enters the air gap to form a high-pressure gas film. The gas spring piston, the power piston and the phase modulator are supported, gas floating supporting points are moved to the two sides from the center, and the torque resistance is improved.

Description

Technical Field

[0001] This invention relates to the field of free piston thermoacoustic Stirling machine technology, and more particularly to a free piston thermoacoustic Stirling machine air-floating piston structure. Background Technology

[0002] Free-piston thermoacoustic Stirling engines possess advantages such as high efficiency, high reliability, and compact structure, and have significant application potential in aerospace, military, and biomedicine fields. In free-piston thermoacoustic Stirling engines, the piston typically employs an air-supported design, utilizing gas instead of lubricating oil as the lubricant. This creates a high-pressure gas film between the piston and cylinder, supporting the piston and ensuring a consistently small gap between them. This eliminates mechanical wear and achieves a gap sealing effect, thereby significantly extending the service life of the reciprocating piston.

[0003] In existing technologies, such as Figure 1 As shown, to meet the rigidity required for higher power operation, the leaf spring supporting the phase adjuster 10 can be replaced by a gas spring piston 20. This gas support structure uses internal gas supply, that is, it utilizes the pressure fluctuations in the system in combination with a one-way valve 30 to generate a high-pressure gas chamber 40 and a low-pressure chamber. The power piston 50 is designed with a high-pressure gas chamber 40 inside. A one-way valve 30 is installed between the end face of the high-pressure gas chamber 40 facing the compression chamber 60 and the compression chamber 60, so that the airflow can only flow from the compression chamber 60 to the high-pressure gas chamber 40. A double row of gas supply throttling orifices 70 is designed between the high-pressure gas chamber 40 and the sealing air gap 100. After the system starts running, the power piston 50 begins high-frequency reciprocating motion, causing the compression chamber 60 to generate pressure waves. When the pressure in the compression chamber 60 rises to a certain value, the one-way valve 30 opens, and gas enters the high-pressure gas chamber 40 from the compression chamber 60 and maintains a high supply pressure. Under the influence of pressure difference, high-pressure gas is throttled through the gas supply throttle orifice 70 and enters the sealed air gap 100, flowing towards the exhaust areas on both sides of the power piston 50. This provides support for the gas spring piston 20 and Rod rod 80, creating a gas lubrication effect. High-pressure gas films are formed between the power piston 20 and the cylinder 90, and between the power piston 50 and the Rod rod 80. Furthermore, the Rod rod 80 is connected to the gas spring piston 20 and the phase adjuster 10, thereby eliminating mechanical wear between the gas spring piston 20 and the phase adjuster 10 and the cylinder 90.

[0004] However, the aforementioned air flotation structure has poor torque resistance because the air supply throttle orifice is only present on the main piston. If the system's center of gravity shifts, it will cause wear between the power piston 50 and the cylinder 90, affecting the system's operation. Summary of the Invention

[0005] This invention provides a free piston thermoacoustic Stirling engine air-floating piston structure to solve the defect of poor torque resistance of existing air-floating piston structures and improve the torque resistance of the system.

[0006] This invention provides a free-piston thermoacoustic Stirling engine air-floating piston structure, comprising: The cylinder has an internal mounting cavity; The phase adjuster, power piston, and gas spring piston are all disposed within the mounting cavity. A Rod rod is connected to one side of the phase adjuster, which passes through the power piston and connects to the gas spring piston. Air gaps are provided between the gas spring piston and the inner wall of the cylinder, between the power piston and the inner wall of the cylinder, and between the phase adjuster and the inner wall of the cylinder. A compression chamber is located between the phase adjuster and the power piston. An air supply line is distributed on the inner wall of the cylinder corresponding to the axial positions of the phase adjuster, the power piston and the gas spring piston, and one end of the air supply line is connected to the air gap; A high-pressure air chamber is located on the outside of the cylinder, and the other end of the air supply pipeline is connected to the high-pressure air chamber; the high-pressure gas in the high-pressure air chamber enters the air gap to form a high-pressure air film.

[0007] According to the present invention, a free-piston thermoacoustic Stirling engine air-floating piston structure is provided, wherein the air supply pipeline includes: Multiple air supply throttle orifices are located on the inner wall of the cylinder, and at least one set of air supply throttle orifices is provided at the axial position of the phase adjuster, the power piston, and the gas spring piston; The pipeline body is disposed inside the inner wall of the cylinder. The pipeline body is arranged parallel to the axis of the phase adjuster, the power piston and the gas spring piston. The pipeline body is connected to the air supply throttle orifice and the high-pressure air chamber.

[0008] According to the present invention, a free piston thermoacoustic Stirling engine air-floating piston structure is provided, wherein the phase adjuster, the power piston, and the gas spring piston are each provided with two sets of air supply throttling orifices.

[0009] According to the present invention, a free-piston thermoacoustic Stirling engine air-floating piston structure is provided, wherein a back cavity is formed between the cylinder and the housing of the free-piston thermoacoustic Stirling engine, and further includes a first annular return air groove and a plurality of first return air holes. The first annular return air groove is formed on the inner wall of the cylinder, and the first return air holes are all connected to the first annular return air groove. The first annular return air groove is connected to the air gap, and the first return air holes are connected to the back cavity.

[0010] According to the present invention, a free piston thermoacoustic Stirling engine air-floating piston structure is provided, wherein the first annular return groove is vertically disposed on the inner wall surface of the cylinder, and the first annular return groove is disposed corresponding to the axial position of the gas spring piston, so that the air gap between the gas spring piston and the cylinder is connected to the back cavity.

[0011] According to the present invention, a free piston thermoacoustic Stirling engine air-floating piston structure further includes a second annular return groove and a plurality of second return holes. The second annular return groove is disposed on the inner wall of the cylinder, and the second return holes are all connected to the second annular return groove. The second annular return groove is connected to the air gap, and the second return holes are connected to the compression chamber.

[0012] According to the present invention, a free piston thermoacoustic Stirling engine air-floating piston structure is provided, wherein the second annular return groove is disposed on the inner wall surface of the cylinder corresponding to the axial position of the phase adjuster, so that the air gap between the phase adjuster and the cylinder is connected to the compression chamber.

[0013] According to the present invention, a free piston thermoacoustic Stirling engine air-floating piston structure is provided, wherein a one-way valve is provided between the compression chamber and the high-pressure air chamber, and the one-way valve only allows opening in one direction from the compression chamber to the high-pressure air chamber.

[0014] According to the present invention, a free piston thermoacoustic Stirling machine air-floating piston structure further includes a cylinder fixing flange, which has the high-pressure air chamber inside and communicates with the compression chamber on the outside, and the one-way valve is disposed on the cylinder fixing flange.

[0015] According to the present invention, a free piston thermoacoustic Stirling engine air-floating piston structure further includes a dome cylinder disposed at one end opposite to the Rod rod of the phase tuner.

[0016] The air-floating piston structure provided by this invention features an installation cavity within the cylinder. The phase adjuster, power piston, and gas spring piston are all housed within this cavity. A Rod rod is connected to one side of the phase adjuster, passing through the power piston and connecting to the gas spring piston. Air gaps are maintained between the gas spring piston and the cylinder wall, between the power piston and the cylinder wall, and between the phase adjuster and the cylinder wall. A compression chamber exists between the phase adjuster and the power piston. Air supply lines are distributed along the inner wall of the cylinder, corresponding to the axial positions of the phase adjuster, power piston, and gas spring piston, with one end of the air supply line connected to the air gap. A high-pressure air chamber is located on the outer side of the cylinder, with the other end of the air supply line connected to it. High-pressure gas from the high-pressure air chamber enters the air gap, forming a high-pressure gas film that supports the gas spring piston, power piston, and phase adjuster. Compared to traditional air-floating piston structures, this invention provides air-floating support points for the gas spring piston, phase adjuster, and cylinder, shifting these support points from the center to both sides, thereby reducing the lever arm and significantly improving the system's torque resistance. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of the air-floating piston structure provided by existing technology.

[0019] Figure 2 This is one of the structural schematic diagrams of the air-floating piston structure provided by the present invention.

[0020] Figure 3 This is the second schematic diagram of the air-floating piston structure provided by the present invention.

[0021] Figure label: 1. Cylinder; 2. Phase adjuster; 3. Power piston; 4. Gas spring piston; 5. Rod rod; 6. Air gap; 7. Compression chamber; 8. High-pressure air chamber; 9. Air supply throttle orifice; 10. Pipeline body; 11. Back cavity; 12. First annular return air groove; 13. One-way valve; 14. Cylinder fixing flange; 15. Dome cylinder; 16. Spring cavity; 17. First return air hole; 18. Second annular return air groove; 19. Second return air hole. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0023] In the description of the embodiments of the present invention, it should be noted that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of the present invention. In addition, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0024] The following is combined Figures 2-3 The present invention describes the free piston thermoacoustic Stirling engine air-floating piston structure.

[0025] like Figure 2 As shown, the present invention provides a free piston thermoacoustic Stirling engine air-floating piston structure, including a cylinder 1, a phase adjuster 2, a power piston 3, a gas spring piston 4, a Rod rod 5, an air gap 6, a compression chamber 7, and a high-pressure air chamber 8.

[0026] The cylinder 1 has an installation cavity. The phase adjuster 2, the power piston 3, and the gas spring piston 4 are all located within the installation cavity. A Rod rod 5 is connected to one side of the phase adjuster 2, passing through the power piston 3 and connecting to the gas spring piston 4. Air gaps 6 are provided between the gas spring piston 4 and the inner wall of the cylinder 1, between the power piston 3 and the inner wall of the cylinder 1, and between the phase adjuster 2 and the inner wall of the cylinder 1. A compression cavity 7 is located between the phase adjuster 2 and the power piston 3. The air supply pipeline is distributed on the inner wall of the cylinder 1, corresponding to the axial positions of the phase adjuster 2, the power piston 3, and the gas spring piston 4, and one end of the air supply pipeline is connected to the air gap 6. A high-pressure air chamber 8 is located on the outside of the cylinder 1, and the other end of the air supply pipeline is connected to the high-pressure air chamber 8. The high-pressure gas in the high-pressure air chamber 8 enters the air gap 6, forming a high-pressure air film, which supports the gas spring piston 4, the power piston 3, and the phase adjuster 2. Compared with the traditional air-floating piston structure, the gas spring piston 4, phase adjuster 2 and cylinder 1 of the present invention all have air-floating support points, which move the air-floating support points from the center to both sides, thereby reducing the lever arm and greatly improving the system's anti-torque capability.

[0027] More specifically, the gas supply pipeline includes multiple gas supply throttling orifices 9 and a pipeline body 10. The multiple gas supply throttling orifices 9 are located on the inner wall of the cylinder 1, and at least one set of gas supply throttling orifices 9 is provided in the axial position of the phase adjuster 2, the power piston 3, and the gas spring piston 4. The pipeline body 10 is located inside the inner wall of the cylinder 1, and is arranged parallel to the axial direction of the phase adjuster 2, the power piston 3, and the gas spring piston 4. The pipeline body 10 is connected to the gas supply throttling orifices 9 and is also connected to the high-pressure gas chamber 8. After the system starts, the reciprocating motion of the power piston 3 will cause the pressure in the compression chamber 7 and the back chamber 11 to change. When the pressure in the compression chamber 7 rises to a certain value, the gas enters the high-pressure gas chamber 8 from the compression chamber 7. The high-pressure gas in the high-pressure gas chamber 8 flows from the pipeline body 10 into the gas supply throttling orifices 9, and then into the air gap 6, forming a high-pressure gas film, which supports the gas spring piston 4, the power piston 3, and the phase adjuster 2.

[0028] In a feasible embodiment of the present invention, the phase adjuster 2, the power piston 3, and the gas spring piston 4 are all provided with dual sets of gas supply throttling orifices 9. The dual sets of gas supply throttling orifices 9 allow for more precise control of the high-pressure gas flow rate entering the air gap 6. By adjusting the diameter, number, and arrangement of the gas supply throttling orifices 9, precise adjustment of the gas flow rate can be achieved, thereby ensuring the stability and consistency of the high-pressure gas film. Furthermore, the dual sets of gas supply throttling orifices 9 on the phase adjuster 2, the power piston 3, and the gas spring piston 4 provide a larger gas flow area, enabling a shorter response time to changes in the system's gas flow rate requirements.

[0029] like Figure 3 As shown, in a feasible embodiment of the present invention, a back cavity 11 is formed between the cylinder 1 and the housing of the free piston thermoacoustic Stirling engine, and further includes a first annular return air groove 12 and a first return air hole 17. The first annular return air groove 12 is formed on the inner wall of the cylinder 1, and the first return air hole 17 is connected to the first annular return air groove 12. The first annular return air groove 12 is connected to the air gap 6, and the first return air hole 17 is connected to the back cavity 11. More specifically, the first annular return air groove 12 is vertically arranged on the inner wall surface of the cylinder 1, and the first annular return air groove 12 is arranged corresponding to the axial position of the gas spring piston 4, so that the air gap between the gas spring piston 4 and the cylinder 1 is connected to the back cavity 11. During system operation, the high-pressure gas supplied by the high-pressure air chamber 8 enters the three air gaps 6 through the air supply pipe on the cylinder 1 to form a high-pressure air film, which supports the power piston 3. Then, the gas in the high-pressure air film flows into the back cavity 11 through the first annular return air groove 12, forming a gas passage to ensure that the pressure in the high-pressure air film is constant, while reducing the entry of floating gas into the spring cavity 16, avoiding piston drift and the loss of cooling caused by the mixing of hot and cold gases.

[0030] In a feasible embodiment of the present invention, a second annular return air groove 18 and a plurality of second return air holes 19 are also included. The second annular return air groove 18 is formed on the inner wall of the cylinder 1, and the second return air holes 19 are all connected to the second annular return air groove 18. The second annular return air groove 18 is connected to the air gap 6, and the second return air holes 19 are all connected to the compression chamber 7. The second annular return air groove 18 is provided on the inner wall surface of the cylinder 1 corresponding to the axial position of the phase adjuster 2, so that the air gap between the phase adjuster 2 and the cylinder 1 is connected to the compression chamber 7. During system operation, the high-pressure gas provided by the high-pressure air chamber 8 enters the three air gaps 6 from the air supply pipeline on the cylinder 1 to form a high-pressure gas film, which supports the power piston 3. Then, the gas in the high-pressure gas film flows into the compression chamber 7 through the second annular return air groove 18 to form a gas passage, ensuring that the pressure in the high-pressure gas film is constant, while reducing the entry of floating gas into the dome cylinder 15 side, avoiding piston drift and cold loss caused by the mixing of hot and cold gases.

[0031] In a feasible embodiment of the present invention, a one-way valve 13 is provided between the compression chamber 7 and the high-pressure air chamber 8, and the one-way valve 13 only allows opening in one direction from the compression chamber 7 to the high-pressure air chamber 8. The presence of the one-way valve 13 ensures that when the compression chamber 7 is compressed, its internal pressure can be smoothly transmitted to the high-pressure air chamber 8. In this way, the high-pressure air chamber 8 can store and maintain a certain pressure level, providing a stable high-pressure gas source for the air flotation support system. At the same time, due to the restriction of the one-way valve 13, the high-pressure gas in the high-pressure air chamber 8 will not flow back into the compression chamber 7, thereby maintaining the pressure stability within the compression chamber 7.

[0032] In a feasible embodiment of the present invention, a cylinder fixing flange 14 is further included, which has a high-pressure air chamber 8 inside and is connected to the compression chamber 7 on the outside. A one-way valve 13 is disposed on the cylinder fixing flange 14. The cylinder fixing flange 14 not only serves as a fixing component for the cylinder 1, but also integrates the function of the high-pressure air chamber 8. This design greatly saves space, making the entire air-floating piston structure more compact. At the same time, placing the one-way valve 13 directly on the cylinder fixing flange 14 reduces the use of connecting parts and pipelines, further simplifying the system structure. The high-pressure air chamber 8 is cleverly disposed inside the cylinder fixing flange 14, which makes the storage and transmission of high-pressure gas more direct and efficient. Since the high-pressure air chamber 8 is adjacent to the compression chamber 7 and the two are connected by the one-way valve 13, when the pressure in the compression chamber 7 increases, the high-pressure gas can quickly and smoothly enter the high-pressure air chamber 8 for storage.

[0033] The air-floating piston structure provided by the present invention includes a cylinder 1, a phase adjuster 2, a power piston 3, a gas spring piston 4, a rod 5, an air gap 6, a compression chamber 7, a high-pressure air chamber 8, an air supply throttling orifice 9, a pipeline body 10, a back cavity 11, a first annular return air groove 12, a one-way valve 13, a cylinder fixing flange 14, a dome cylinder 15, a spring cavity 16, a first return air hole 17, a second annular return air groove 18, and a second return air hole 19.

[0034] Rod 5 passes through the power piston 3 and connects to the gas spring piston 4, providing the stiffness required for high-power operation. Air gaps 6 are provided between the gas spring piston 4, power piston 3, phase adjuster 2, and the inner wall of cylinder 1. The inner wall of cylinder 1 has two sets of circumferentially arranged air supply throttle holes 9 at axial positions corresponding to the gas spring piston 4, power piston 3, and phase adjuster 2. The air gaps 6 are connected to the high-pressure air chamber 8 located outside the cylinder via an internal air supply line. After system startup, the reciprocating motion of the power piston 3 causes pressure changes in the compression chamber 7 and the back chamber 11. When the pressure in the compression chamber 7 rises to a certain value, the one-way valve 13 between it and the high-pressure air chamber 8 opens, allowing gas to enter the high-pressure air chamber 8 from the compression chamber 7. The high-pressure gas in the high-pressure air chamber 8 flows into the three air gaps 6 of cylinder 1 through the air supply line on cylinder 1, forming a high-pressure gas film that supports the gas spring piston 4, power piston 3, and phase adjuster 2. Compared with the traditional air flotation structure, this structure adds a double set of air supply throttle holes 9 in the gap between the gas spring piston 4 and the phase adjuster 2 and the cylinder 1, so that the air flotation support point is moved from the center to both sides, thereby reducing the lever arm and greatly improving the system's anti-torque capability.

[0035] Furthermore, two annular return gas grooves are arranged circumferentially along the cylinder 1. The first annular return gas groove 12 is located on the inner wall surface of the cylinder 1 corresponding to the axial position of the gas spring piston 4, connecting the air gap 6 between the gas spring piston 4 and the cylinder 1 to the back cavity 11. The second annular return gas groove 18 is located on the inner wall surface of the cylinder 1 corresponding to the axial position of the phase adjuster 2, connecting the air gap 6 between the phase adjuster 2 and the cylinder 1 to the compression chamber 7. During system operation, the high-pressure gas supplied by the high-pressure gas chamber 8 enters the three air gaps 6 from the gas supply pipeline on the cylinder 1 to form a high-pressure gas film, which supports the power piston 3. Then, the gas in the high-pressure gas film flows back to the back cavity 11 through the first annular return gas groove 12 or back to the compression chamber 7 through the second annular return gas groove 18, forming a gas passage to ensure constant pressure in the high-pressure gas film, while reducing the entry of floating gas into the spring cavity 16 and dome cylinder 15, avoiding piston drift and cold loss caused by mixing of hot and cold gases.

[0036] In the description of the embodiments of the present invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "connected" and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of the present invention according to the specific circumstances.

[0037] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "method," "specific method," or "some methods," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or method is included in at least one embodiment or method of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or method. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or methods. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or methods described in this specification, as well as the features of different embodiments or methods.

[0038] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A free-piston thermoacoustic Stirling engine air-floating piston structure, characterized in that, include: Cylinder (1), which has an internal mounting cavity; The phase adjuster (2), the power piston (3), and the gas spring piston (4) are all located in the mounting cavity. A Rod rod (5) is connected to one side of the phase adjuster. The Rod rod (5) passes through the power piston (3) and is connected to the gas spring piston (4). Air gaps (6) are left between the gas spring piston (4) and the inner wall of the cylinder (1), between the power piston (3) and the inner wall of the cylinder (1), and between the phase adjuster (2) and the inner wall of the cylinder (1). A compression chamber (7) is located between the phase adjuster (2) and the power piston (3). The air supply line is distributed on the inner wall of the cylinder (1) corresponding to the axial positions of the phase adjuster (2), the power piston (3) and the gas spring piston (4), and one end of the air supply line is connected to the air gap (6). The high-pressure air chamber (8) is located on the outside of the cylinder (1), and the other end of the air supply pipeline is connected to the high-pressure air chamber (8); the high-pressure gas in the high-pressure air chamber (8) enters the air gap (6) to form a high-pressure air film.

2. The free-piston thermoacoustic Stirling engine air-floating piston structure according to claim 1, characterized in that, The gas supply pipeline includes: Multiple air supply throttle holes (9) are located on the inner wall of the cylinder (1), and at least one set of air supply throttle holes (9) is provided in the axial position of the phase adjuster (2), the power piston (3) and the gas spring piston (4). The pipeline body (10) is located inside the inner wall of the cylinder (1). The pipeline body (10) is arranged parallel to the axis of the phase adjuster (2), the power piston (3) and the gas spring piston (4). The pipeline body (10) is connected to the air supply throttle hole (9) and the pipeline body (10) is connected to the high pressure air chamber (8).

3. The free-piston thermoacoustic Stirling engine air-floating piston structure according to claim 2, characterized in that, The phase adjuster (2), the power piston (3) and the gas spring piston (4) are each provided with two sets of gas supply throttling orifices (9).

4. The free-piston thermoacoustic Stirling engine air-floating piston structure according to claim 1, characterized in that, The cylinder (1) forms a back cavity (11) between itself and the housing of the free piston thermoacoustic Stirling engine. It also includes a first annular return air groove (12) and a plurality of first return air holes (17). The first annular return air groove (12) is opened on the inner wall of the cylinder (1), and the first return air holes (17) are all connected to the first annular return air groove (12). The first annular return air groove (12) is connected to the air gap (6), and the first return air holes (17) are connected to the back cavity (11).

5. The free-piston thermoacoustic Stirling engine air-floating piston structure according to claim 4, characterized in that, The first annular return groove (12) is vertically disposed on the inner wall surface of the cylinder (1), and the first annular return groove (12) is disposed corresponding to the axial position of the gas spring piston (4) so ​​that the air gap (6) between the gas spring piston (4) and the cylinder (1) is connected to the back cavity (11).

6. The free-piston thermoacoustic Stirling engine air-floating piston structure according to claim 4, characterized in that, It also includes a second annular return air groove (18) and a plurality of second return air holes (19). The second annular return air groove (18) is opened on the inner wall of the cylinder (1). The second return air holes (19) are all connected to the second annular return air groove (18). The second annular return air groove (18) is connected to the air gap (6). The second return air holes (19) are connected to the compression chamber (7).

7. The free-piston thermoacoustic Stirling engine air-floating piston structure according to claim 6, characterized in that, The second annular return air groove (18) is disposed on the inner wall surface of the cylinder (1) corresponding to the axial position of the phase adjuster (2), so that the air gap (6) between the phase adjuster (2) and the cylinder (1) is connected to the compression chamber (7).

8. The free-piston thermoacoustic Stirling engine air-floating piston structure according to claim 1, characterized in that, A one-way valve (13) is provided between the compression chamber and the high-pressure air chamber (8), and the one-way valve (13) only allows one-way opening from the compression chamber (7) to the high-pressure air chamber (8).

9. The free-piston thermoacoustic Stirling engine air-floating piston structure according to claim 8, characterized in that, It also includes a cylinder fixing flange (14), which has the high-pressure air chamber (8) inside and is connected to the compression chamber (7) on the outside, and the one-way valve (13) is disposed on the cylinder fixing flange (14).

10. The free-piston thermoacoustic Stirling engine air-floating piston structure according to claim 8, characterized in that, It also includes a dome tube (15), which is located at one end of the phase adjuster (2) opposite to the Rod rod (5).

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