Gas bearing structure for linear compressor of Stirling cryocooler

Abstract

The invention belongs to the technical field of gas bearings, and relates to a gas bearing structure for a linear compressor of a Stirling cryocooler, the gas bearing structure comprises a first row of throttling holes formed in a piston and a third row of throttling holes formed in an air cylinder, and the third row of throttling holes are communicated with a compression cavity of the air cylinder through a bypass thin channel formed in the air cylinder; the first row of throttling holes sprays air to the inner wall of the air cylinder, the third row of throttling holes sprays air to the outer wall of the piston, the piston is located in the air cylinder, and an air film gap exists between the outer wall of the piston and the inner wall of the air cylinder so that the wall faces of the piston and the inner wall of the air cylinder can not make contact. The mode that the throttling holes are evenly distributed in the axial direction is changed, the third row of throttling holes are additionally formed between the first row of throttling holes and the second row of throttling holes, the third row of throttling holes is changed into the mode that air is sprayed inwards (towards the outer wall of the piston), and due to the fact that the third row of throttling holes is additionally formed, the balance of gas bearing capacity in the axial direction is improved; and radial supporting force is provided in the whole period.

Description

Technical Field

[0001] This invention relates to the field of gas bearing technology, and in particular to a gas bearing structure for a Stirling refrigerator linear compressor. Background Technology

[0002] With the development of science and technology and the increasing demands of applications, the aerospace and military fields have placed more stringent requirements on cryogenic refrigerators. Traditional support methods for linear Stirling refrigerators mainly rely on leaf springs, but these technologies have significant limitations. Furthermore, especially in extreme application environments such as aerospace, equipment maintenance and replacement are extremely difficult. Therefore, achieving non-contact operation of moving parts has become a core objective in the long-life design of Stirling refrigerators. For Stirling refrigerators using gas bearings, high lifespan, low wear, and high reliability are their significant advantages.

[0003] The application of gas bearing technology and clearance seals introduces a high-pressure gas film to lubricate and support the piston and cylinder, fundamentally eliminating solid contact and thus solving the problems of friction and contamination. The application of gas bearings has not only significantly improved the lifespan of refrigeration units and reduced vibration and noise, but also increased system efficiency. However, the design and application of gas bearings still face a series of complex challenges, including optimizing the dynamic stability of the gas film, bearing stiffness, and load-bearing capacity.

[0004] Structure and principle of hydrodynamic gas bearings: Currently, gas bearing structures mainly consist of those with a stable external high-pressure gas source, such as... Figure 1 As shown, it is commonly used for the lubrication and support of high-speed rotating bearings.

[0005] In Stirling refrigerators, the gas bearing structure of the linear compressor is a self-supply structure for the compression chamber. The piston performs reciprocating linear motion, and the piston is floated by components such as a one-way valve, a gas storage chamber, and a throttling orifice. Figure 2 As shown, the gas bearing linear compressor mainly consists of a piston, cylinder, one-way valve, compression chamber, back pressure chamber, gas storage chamber, gas film, and throttling orifice assembly. The piston is hollow, and its internal cavity (i.e., the gas storage chamber) is connected to the throttling orifice (…). Figure 2The throttling orifices 1 and 2 in the piston are connected to the film gas gap, forming a fluid domain with the compression chamber and back pressure chamber, and a one-way valve is installed on one side of the compression chamber. The piston is supported by the film gas and has no contact with the cylinder wall, thus avoiding wear between the piston and the cylinder wall. In addition, due to the presence of the one-way valve, when the piston is compressed, high-pressure gas flows from the compression chamber into the piston's gas storage chamber as a high-pressure gas source, and when the piston expands, the high-pressure gas in the gas storage chamber will not flow back to the compression chamber because the one-way valve is closed, thus ensuring that the hollow part of the piston has a high pressure. The first row of throttling orifices (composed of multiple throttling orifices 1 in the circumferential direction) and the second row of throttling orifices (composed of multiple throttling orifices 2 in the circumferential direction) are usually arranged axially symmetrically, that is, equidistant from the piston centerline, such as Figure 2 As shown.

[0006] However, research revealed that the gas bearing ejects relatively little gas at the first row of orifices, and even exhibits reverse suction during half a piston cycle, meaning gas flows from the gas film into the orifices. This results in weaker gas film support near the compression chamber, or even no support at all during half a cycle, causing the piston to tilt axially. Simultaneously, due to the piston's cantilever beam structure, the support near the compression chamber is inherently weak, requiring greater support. Consequently, the piston easily contacts the cylinder wall on the axial side near orifice 2. The reason for this is that the pressure within the gas film at this location is higher than the pressure in the storage chamber during half a cycle, while the pressure difference between the storage chamber and the gas film is smaller during the other half-cycle.

[0007] It should be noted that the information disclosed in the background section above is only used to enhance the understanding of the background of the present invention, and therefore may include information that does not constitute prior art known to those skilled in the art. Summary of the Invention

[0008] The purpose of this invention is to solve the technical problem of uneven jet flow in existing dual-row jet throttle orifices. To this end, a gas bearing structure for a Stirling refrigeration linear compressor is provided.

[0009] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A gas bearing structure for a Stirling refrigerator linear compressor includes a first row of throttling orifices on a piston and a third row of throttling orifices on a cylinder, wherein the third row of throttling orifices is connected to the compression chamber of the cylinder through a bypass channel on the cylinder. The first row of throttle orifices sprays air towards the inner wall of the cylinder, and the third row of throttle orifices sprays air towards the outer wall of the piston. The piston is inside the cylinder, and there is a film gap between the outer wall of the piston and the inner wall of the cylinder so that the two walls do not contact each other.

[0010] The following is a further defined technical solution of the present invention: the axial position of the first row of throttling orifices is 3 / 8 of the distance from the leftmost end of the piston, and the axial position of the third row of throttling orifices is 5 / 18 of the distance from the rightmost end of the piston.

[0011] The following is a further defined technical solution of the present invention, which also includes a second row of throttle holes opened on the piston, wherein the jet direction of the second row of throttle holes is towards the inner wall of the cylinder, and the third row of throttle holes is located between the first row of throttle holes and the second row of throttle holes in the axial direction (referring to the cylinder axis or piston axis).

[0012] The following is a further defined technical solution of the present invention: the axial position of the first row of throttling orifices is between 1 / 4 and 1 / 2 of the distance from the leftmost end of the piston; the axial position of the second row of throttling orifices is between 1 / 6 and 1 / 4 of the distance from the rightmost end of the piston; and the axial position of the third row of throttling orifices is close to the left side of the axial position of the second row of throttling orifices.

[0013] The following is a further defined technical solution of the present invention: the axial position of the first row of throttling orifices is 1 / 3 of the distance from the leftmost end of the piston, the axial position of the second row of throttling orifices is 1 / 6 of the distance from the rightmost end of the piston, and the axial position of the third row of throttling orifices is 5 / 18 of the distance from the rightmost end of the piston.

[0014] The following is a further defined technical solution of the present invention: the first row of throttling orifices includes a plurality of throttling orifices arranged in the circumferential direction, the throttling orifices being evenly distributed to adapt to the working condition where the piston is in a vertical state. The second row of throttling orifices includes multiple throttling orifices II arranged in the circumferential direction. The throttling orifices II are evenly distributed to adapt to the working condition where the piston is in a vertical state. The third row of throttling orifices includes multiple throttling orifices arranged in the circumferential direction. The throttling orifices are evenly distributed to adapt to the working condition where the piston is in a vertical state.

[0015] The following is a further defined technical solution of the present invention: the first row of throttling orifices includes a plurality of throttling orifices arranged in the circumferential direction. The throttling orifices are symmetrical from left to right and the spacing between adjacent throttling orifices decreases from top to bottom to adapt to the working condition where the piston is in a horizontal state. The second row of throttling orifices includes multiple throttling orifices II arranged in the circumferential direction. The throttling orifices II are symmetrical from left to right and the spacing between adjacent throttling orifices II decreases from top to bottom to adapt to the working condition where the piston is in a horizontal state. The third row of throttling orifices includes multiple throttling orifices arranged in the circumferential direction. The throttling orifices are symmetrical from left to right and the spacing between adjacent throttling orifices decreases from top to bottom to adapt to the working condition where the piston is in a horizontal state.

[0016] The following is a further defined technical solution of the present invention, wherein the diameter of the bypass fine channel is less than 1 mm.

[0017] Compared with the prior art, the present invention has the following technical effects: This invention changes the way the throttle orifices are uniformly arranged along the axial direction, and adds a third row of throttle orifices between the first row and the second row. The third row of throttle orifices changes from spraying air outward (to the inner wall of the cylinder) to spraying air inward (to the outer wall of the piston). By adding a bypass narrow channel directly connected to the compression chamber, the addition of the third row of throttle orifices improves the uniform distribution of gas carrying capacity in the axial direction and provides radial support force throughout the cycle.

[0018] The present invention will be further described below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a structural diagram of a hydrostatic thrust gas bearing; Figure 2 This is a schematic diagram of the current gas bearing structure of a linear compressor; Figure 3 This is a schematic diagram of the gas bearing structure of the present invention; Figure 4 This is a schematic diagram of the circumferential distribution of the throttling orifice in the gas bearing structure of the present invention.

[0021] Reference numerals in the attached diagram: 1. First row of throttling orifices; 2. Second row of throttling orifices; 3. Third row of throttling orifices; 4. Gas storage chamber; 5. One-way valve; 6. Piston; 7. Cylinder; 8. Inlet and outlet; 9. Bypass narrow channel. Detailed Implementation

[0022] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of the present invention. However, the present invention can be practiced in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0023] In the description of this invention, it should be understood that the terms "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "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 this 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 this invention.

[0024] In the description of this invention, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0025] In the embodiments of the present invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; 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; they can refer to the internal communication of two components or the interaction between two components. 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.

[0026] Example 1: like Figure 3As shown, a gas bearing structure for a Stirling refrigerator linear compressor is provided, including a first row of throttling orifices 1 and a second row of throttling orifices 2 formed on a piston 6, and a third row of throttling orifices 3 formed on a cylinder 7, together forming a throttling orifice assembly. The third row of throttling orifices 3 is connected to the compression chamber of the cylinder 7 through a bypass channel 9 provided on the cylinder 7, wherein the diameter of the bypass channel 9 is less than 1 mm. The jet direction of the first row of throttling orifices 1 is towards the inner wall of the cylinder 7, the jet direction of the second row of throttling orifices 2 is towards the inner wall of the cylinder 7, and the jet direction of the third row of throttling orifices 3 is towards the outer wall of the piston 6. The piston 6 is located inside the cylinder 7, and there is a film gap between the outer wall of the piston 6 and the inner wall of the cylinder 7 so that the two walls do not contact each other; the axial position of the third row of throttling orifices 3 (referring to the axial direction of the cylinder 7 or the axial direction of the piston 6) is between the first row of throttling orifices 1 and the second row of throttling orifices 2. The axial position of the first row of throttling orifices 1 is between 1 / 4 and 1 / 2 of the distance from the leftmost end of the piston 6. The axial position of the second row of throttling orifices 2 is between 1 / 6 and 1 / 4 of the distance from the rightmost end of the piston 6. The axial position of the third row of throttling orifices 3 is close to the left side of the axial position of the second row of throttling orifices 2. Ideally, the axial position of the first row of throttling orifices 1 is 1 / 3 of the distance from the leftmost end of the piston 6, the axial position of the second row of throttling orifices 2 is 1 / 6 of the distance from the rightmost end of the piston 6, and the axial position of the third row of throttling orifices 3 is 5 / 18 of the distance from the rightmost end of the piston 6.

[0027] The piston 6 has a hollow structure, and its internal cavity is a gas storage chamber 4. The gas storage chamber 4 is connected to the gas film gap through the first row of throttling holes 1 and the second row of throttling holes 2. The compression chamber of the cylinder 7 is connected to the gas film gap through the bypass narrow channel 9 and the third row of throttling holes 3. A one-way valve 5 is provided on the side of the piston 6 near the compression chamber, and an inlet and outlet 8 are provided on the side of the cylinder 7 near the compression chamber.

[0028] To avoid Figure 2 This embodiment changes the axial uniform or symmetrical arrangement of the throttle orifices centered on the midpoint of the piston axis, and adds a third row of throttle orifices 3 (with opposite jet directions) between the first row of throttle orifices 1 and the second row of throttle orifices 2. Figure 3 As shown, the third row of throttling orifices 3 changes from spraying air outwards (to the inner wall of cylinder 7) to spraying air inwards (to the outer wall of piston 6), and is directly connected to the compression chamber by adding a bypass narrow channel 9. Since the pressure in the compression chamber is higher than the pressure inside the gas film, the airflow is ejected through the third row of throttling orifices 3, pushing the piston 6 away and preventing it from contacting the cylinder 7. This invention, by adding the third row of throttling orifices 3, improves the axial balance of the gas bearing capacity and provides radial support force throughout the entire cycle.

[0029] When the piston 6 is in a vertical operating state, the throttling orifices are evenly distributed in the circumferential direction. Specifically: the first row of throttling orifices 1 includes multiple throttling orifices I arranged in the circumferential direction, and the throttling orifices I are evenly distributed; the second row of throttling orifices 2 includes multiple throttling orifices II arranged in the circumferential direction, and the throttling orifices II are evenly distributed; the third row of throttling orifices 3 includes multiple throttling orifices III arranged in the circumferential direction, and the throttling orifices III are evenly distributed. Furthermore, the one-way valve 5 is located at the center of the right end face of the piston.

[0030] When piston 6 is in a horizontal operating state, the throttling orifices on the lower half of piston 6 are more densely distributed, specifically: as follows: Figure 4 As shown, the first row of throttling orifices 1 includes multiple throttling orifices one arranged in the circumferential direction. The throttling orifices one are symmetrical from left to right, and the spacing between adjacent throttling orifices one decreases from top to bottom. The second row of throttling orifices 2 includes multiple throttling orifices two arranged in the circumferential direction. The throttling orifices two are symmetrical from left to right, and the spacing between adjacent throttling orifices two decreases from top to bottom. The third row of throttling orifices 3 includes multiple throttling orifices three arranged in the circumferential direction. The throttling orifices three are symmetrical from left to right, and the spacing between adjacent throttling orifices three decreases from top to bottom. The one-way valve 5 is located slightly below the center of the piston's right end face.

[0031] Example 2: A gas bearing structure for a Stirling refrigerator linear compressor has a first row of throttling orifices 1 on the piston 6 and a third row of throttling orifices 3 on the cylinder 7. The axial position of the first row of throttling orifices 1 is 3 / 8 of the distance from the leftmost end of the piston 6, and the axial position of the third row of throttling orifices 3 is 5 / 18 of the distance from the rightmost end of the piston 6.

[0032] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any person skilled in the art can make many possible variations and modifications to the technical solution of the present invention, or modify it into equivalent embodiments, without departing from the scope of the present invention's technical solution. Therefore, all equivalent changes made based on the shape, structure, and principle of the present invention without departing from the scope of the present invention's technical solution should be covered within the protection scope of the present invention.

Claims

1. A gas bearing structure for a Stirling refrigerator linear compressor, comprising a first row of throttling orifices formed on a piston, characterized in that, It also includes a third row of throttling orifices on the cylinder, which are connected to the compression chamber of the cylinder through a bypass channel on the cylinder. The first row of throttle orifices sprays air towards the inner wall of the cylinder, and the third row of throttle orifices sprays air towards the outer wall of the piston. The piston is inside the cylinder, and there is a film gap between the outer wall of the piston and the inner wall of the cylinder so that the two walls do not contact each other.

2. The gas bearing structure for a Stirling refrigerator linear compressor as described in claim 1, characterized in that, The first row of throttling orifices is located at 3 / 8 of the distance from the leftmost end of the piston, and the third row of throttling orifices is located at 5 / 18 of the distance from the rightmost end of the piston.

3. The gas bearing structure for a Stirling refrigerator linear compressor as described in claim 1, characterized in that, It also includes a second row of throttle holes on the piston, the second row of throttle holes being directed to spray air towards the inner wall of the cylinder, and the third row of throttle holes being positioned axially between the first row of throttle holes and the second row of throttle holes.

4. The gas bearing structure for a Stirling refrigerator linear compressor as described in claim 3, characterized in that, The axial position of the first row of throttling orifices is between 1 / 4 and 1 / 2 of the distance from the leftmost end of the piston, the axial position of the second row of throttling orifices is between 1 / 6 and 1 / 4 of the distance from the rightmost end of the piston, and the axial position of the third row of throttling orifices is close to the left of the axial position of the second row of throttling orifices.

5. The gas bearing structure for a Stirling refrigerator linear compressor as described in claim 4, characterized in that, The first row of throttling orifices is located at 1 / 3 of the distance from the leftmost end of the piston, the second row of throttling orifices is located at 1 / 6 of the distance from the rightmost end of the piston, and the third row of throttling orifices is located at 5 / 18 of the distance from the rightmost end of the piston.

6. The gas bearing structure for a Stirling refrigerator linear compressor as described in claim 2, characterized in that, The first row of throttling orifices includes a plurality of throttling orifices arranged in the circumferential direction. The throttling orifices are evenly distributed to adapt to the working condition where the piston is in a vertical state. The second row of throttling orifices includes multiple throttling orifices II arranged in the circumferential direction. The throttling orifices II are evenly distributed to adapt to the working condition where the piston is in a vertical state. The third row of throttling orifices includes multiple throttling orifices arranged in the circumferential direction. The throttling orifices are evenly distributed to adapt to the working condition where the piston is in a vertical state.

7. The gas bearing structure for a Stirling refrigerator linear compressor as described in claim 2, characterized in that, The first row of throttling orifices includes a plurality of throttling orifices I arranged in the circumferential direction. The throttling orifices I are symmetrical from left to right and the spacing between adjacent throttling orifices I decreases from top to bottom to adapt to the working condition where the piston is in a horizontal state. The second row of throttling orifices includes multiple throttling orifices II arranged in the circumferential direction. The throttling orifices II are symmetrical from left to right and the spacing between adjacent throttling orifices II decreases from top to bottom to adapt to the working condition where the piston is in a horizontal state. The third row of throttling orifices includes multiple throttling orifices arranged in the circumferential direction. The throttling orifices are symmetrical from left to right and the spacing between adjacent throttling orifices decreases from top to bottom to adapt to the working condition where the piston is in a horizontal state.

8. The gas bearing structure for a Stirling refrigerator linear compressor as described in any one of claims 1-7, characterized in that, The diameter of the bypass channel is less than 1 mm.

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