Bearings and compressors

Abstract

The present application relates to the field of compressor technology, and specifically to a bearing and a compressor. The present application aims to solve the technical problem that when the rotor rotates at high speed, the bearing is greatly affected by the dynamic pressure effect, which may cause the shaft system to become unstable, restricting its application in small and medium-sized centrifugal compressors. To this end, the bearing of the present application includes: a bearing sleeve, which is provided with an air supply hole; a porous medium layer, which is arranged in the bearing sleeve and enclosed with the bearing sleeve to form an air supply cavity; the inner wall surface of the porous medium layer includes an upper profile and a lower profile in the radial cross-section; a journal is rotatably arranged in the porous medium layer; when the journal is suspended, a first movable gap is formed between the upper profile and the journal, and a second movable gap is formed between the lower profile and the journal; the first movable gap includes at least a first convergent gap with a gradually decreasing thickness, and the second movable gap includes at least a second convergent gap with a gradually decreasing thickness. The present application can improve the stability of the bearing when the rotor rotates at high speed.

Description

Technical Field

[0001] The present application relates to the technical field of compressors, and in particular to a bearing and a compressor. Background Art

[0002] Centrifugal compressors are core components of large refrigeration and air-conditioning units. They compress gas through the centrifugal force generated by the high-speed rotation of the impeller. The air bearings used in oil-free centrifugal compressors are mainly divided into dynamic pressure bearings and static pressure bearings. Dynamic pressure bearings rely on the high-speed rotation of the shaft neck to drive gas into the converging wedge space, creating a high-pressure air film to provide bearing capacity. Dynamic pressure bearings operate based on the principle of dynamic pressure and do not require air supply to the bearing during operation. However, the low viscosity of the gas requires extremely high rotation speeds to provide sufficient bearing capacity, limiting their application in medium-sized and small centrifugal compressors. Static pressure bearings provide bearing capacity by continuously introducing high-pressure gas into a small gap to create a pressure film. The external high-pressure gas is squeezed within the extremely small gap, creating a pressure differential between the upper and lower sides of the shaft neck, thereby keeping the shaft neck in suspension. These bearings offer the advantages of being frictionless, low power, and requiring no takeoff speed requirements, making them more suitable for small and medium-sized centrifugal compressors.

[0003] In the related art, a hydrostatic air bearing includes a bearing sleeve, a porous medium layer and a journal which are sequentially sleeved, and the porous medium layer is in a ring shape.

[0004] When the compressor rotor is stationary or rotating at a low speed, the hydrostatic air bearing relies on externally supplied high-pressure gas to form a pressure film within the gap between the journal and the bearing, achieving stable rotor suspension. However, as the rotor speed increases, the hydrodynamic effect begins to significantly affect the operating characteristics of the hydrostatic air bearing. Under this dynamic pressure effect, the high-speed rotating journal draws gas into the wedge-shaped gap, forming a high-pressure air film. This exerts additional lift on the journal, causing it to move upward closer to the geometric center of the bearing, reducing its eccentricity. Furthermore, this upward movement of the journal increases the gap between the journal and the bearing, increasing the thickness of the air film beneath the journal, leading to a simultaneous decrease in the film's static stiffness and static load-bearing capacity. Simultaneously, the reduced eccentricity makes the wedge-shaped convergence gap less pronounced, weakening the dynamic pressure effect of the air film and, consequently, the lift generated by this dynamic pressure effect. In this situation, when the rotor is subjected to external disturbances, the journal is prone to significant deflection, making it difficult to return to equilibrium, causing sustained oscillation and even shaft instability or even friction.

[0005] Accordingly, this field requires a new technical solution to solve the above problems. Summary of the Invention

[0006] In order to solve at least one of the above problems in the prior art, that is, to solve the technical problem that when the rotor rotates at high speed, the static pressure air suspension bearing is greatly affected by the dynamic pressure effect, which may cause the shaft system to become unstable, thereby restricting its application in small and medium-sized centrifugal compressors.

[0007] In the first aspect, the present application provides a bearing, which includes: a bearing sleeve provided with an air supply hole; a porous medium layer arranged in the bearing sleeve and enclosing the bearing sleeve to form an air supply cavity connected to the air supply hole; the radial cross-section of the inner wall surface of the porous medium layer includes an upper profile and a lower profile, and the lower profile is located below the upper profile along the direction of gravity; a journal is rotatably arranged in the porous medium layer; when the journal is suspended, a first movable gap is formed between the upper profile and the journal, and a second movable gap is formed between the lower profile and the journal; wherein, along the rotation direction of the journal, the first movable gap includes at least a first convergent gap with a gradually decreasing thickness, and the second movable gap includes at least a second convergent gap with a gradually decreasing thickness.

[0008] In some embodiments, the upper profile line and the lower profile line are symmetrically arranged arcs, and the line of symmetry between the upper profile line and the lower profile line is the first line of symmetry; the center of the circle corresponding to the upper profile line is located on the side of the first line of symmetry close to the lower profile line, and the center of the circle corresponding to the lower profile line is located on the side of the first line of symmetry close to the upper profile line.

[0009] In some embodiments, the cross-section of the inner wall surface of the porous medium layer in the radial direction is elliptical, and the length of the symmetry axis of the ellipse along the horizontal direction is greater than the length of the symmetry axis of the ellipse along the vertical direction.

[0010] In some embodiments, the symmetry axes of the figure enclosed by the upper mold line and the lower mold line are the first symmetry axis and the second symmetry axis in the horizontal and vertical directions respectively; wherein, (R L -R S ) / (R L -R j ) ranges from 0.2 to 0.5, R L is the radius of the first symmetry axis, R S is the radius of the second symmetry axis, R j is the radius of the journal.

[0011] In some embodiments, the porous media layer includes an upper porous media layer and a lower porous media layer, and the lower porous media layer is located below the upper porous media layer along the direction of gravity; wherein the porosity of the upper porous media layer is less than the porosity of the lower porous media layer.

[0012] In some embodiments, the porosity of the upper porous medium layer and the lower porous medium layer are both in the range of 10% to 35%.

[0013] In some embodiments, the ratio of the porosity of the upper porous medium layer to the porosity of the lower porous medium layer ranges from 0.4 to 0.6.

[0014] In some embodiments, the material of the porous medium layer includes one or more of porous metal, porous carbon and porous ceramic.

[0015] In some embodiments, the cross-section of the outer wall of the porous medium layer in the radial direction is circular.

[0016] In a second aspect, the present application provides a compressor comprising the bearing of any one of the above embodiments.

[0017] When adopting the above technical solution, the bearing provided by this application forms a gradually decreasing thickness convergent gap between the upper profile and the journal, and between the lower profile and the journal, forming two convergent gaps on the upper and lower sides of the journal. An external high-pressure gas source enters the gas supply cavity through the gas supply hole and then enters the porous medium layer, forming a pressure gas film between the porous medium layer and the journal.

[0018] When the rotor rotates at a low speed, the air film is less affected by the dynamic pressure effect, and the journal is close to the bottom of the porous medium layer due to gravity. The thickness of the pressure air film between the journal and the bottom of the porous medium layer is smaller, and the thickness of the pressure air film between the journal and the top of the porous medium layer is larger. The stiffness of the air film increases with the decrease of thickness. The static stiffness of the air film located on the lower side of the journal is greater than the static stiffness of the air film located on the upper side of the journal. A pressure difference is generated on the upper and lower sides of the journal, causing the journal to suspend.

[0019] As the rotor speed increases, the influence of the dynamic pressure effect of the air film becomes increasingly stronger. Since the journal is close to the bottom of the porous medium layer due to gravity, the convergence gap on the lower side of the journal is more obvious than the convergence gap on the upper side of the journal. The pressure generated in the convergence gap on the lower side of the journal by the dynamic pressure effect is higher than the pressure generated in the convergence gap on the upper side of the journal. Therefore, the journal is lifted by the dynamic pressure effect and moves closer to the geometric center of the bearing, reducing the eccentricity of the journal. As the eccentricity decreases, the convergence gap on the upper side of the journal becomes more obvious, and the pressure generated by the dynamic pressure effect of the air film also increases. At the same time, the convergence gap on the lower side of the journal becomes less obvious, and the pressure generated by the dynamic pressure effect of the air film decreases. The combination of the two stabilizes the center of the journal within a certain range, preventing the further reduction of the journal eccentricity and the further reduction of the static and dynamic stiffness of the air film. The stable air film stiffness increases the journal's ability to resist disturbances and improves the stability of the bearing.

[0020] An air film is generated in the first convergence gap and the second convergence gap. The pressure of the air film is relatively large. The pressure on the inward side of the air film acts on the shaft neck, causing the shaft neck to float in the air supply cavity; the pressure on the outward side of the air film acts on the inner wall surface of the porous medium layer. During the operation of the bearing, air is continuously supplied to the air supply holes, so that the gas forming the air film will not flow out through the porous medium layer, ensuring that there is enough gas in the air supply cavity to form a dynamic pressure air film. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 A schematic diagram of the structure of the bearing provided for this application;

[0022] Figure 2 for Figure 1 Schematic diagram of the positions of the centers of the arcs corresponding to the upper and lower profile lines of the bearing shown;

[0023] Figure 3 A schematic structural diagram of another bearing provided for this application;

[0024] Figure 4 for Figure 1 A labeled schematic diagram of the bearing shown in;

[0025] Figure 5 for Figure 1 Schematic diagram of the side view structure of the bearing shown.

[0026] List of reference numerals: 1. bearing sleeve; 11. air supply hole; 2. porous medium layer; 21. upper mold line; 22. lower mold line; 23. upper porous medium layer; 24. lower porous medium layer; 3. air supply cavity; 4. journal; 5. pressure air film; 51. first movable gap; 511. first convergent gap; 52. second movable gap; 521. second convergent gap. DETAILED DESCRIPTION

[0027] The preferred embodiments of the present application are described below with reference to the accompanying drawings. Those skilled in the art should understand that these embodiments are merely intended to explain the technical principles of the present application and are not intended to limit the scope of protection of the present application. For example, although the following embodiments of the present application are described in conjunction with a compressor, this is not intended to limit the scope of protection of the present application. The present application can also be applied to other devices without departing from the principles of the present application.

[0028] It should be noted that in the description of this application, terms such as "center," "upper," "lower," "vertical," "inner," and "outer" indicating directions or positional relationships are based on the directions or positional relationships shown in the accompanying drawings. This is merely for the convenience of description and does not indicate or imply that the device or element must have a specific orientation, be constructed and operate in a specific orientation. Therefore, it should not be understood as a limitation on this application. In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance. "Multiple" refers to two or more.

[0029] In addition, it should be noted that in the description of this application, unless otherwise specified or limited, the terms "installed," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to internal connections between two components. Those skilled in the art will understand the specific meanings of the above terms in this application.

[0030] In the related art, a hydrostatic air bearing comprises a bearing sleeve, a porous medium layer, and a shaft neck, which are arranged in sequence. The porous medium layer is annular. When the compressor rotor is not rotating or rotating at a low speed, the hydrostatic air bearing relies on externally supplied high-pressure gas to form a pressure air film in the gap between the shaft neck and the bearing, achieving stable suspension of the rotor. However, as the rotor speed increases, the hydrodynamic pressure effect begins to significantly affect the operating characteristics of the hydrostatic air bearing: under the hydrodynamic pressure effect, the high-speed rotating shaft neck draws gas into the wedge-shaped gap to form a high-pressure air film, which causes the shaft neck to experience additional lift. The shaft neck moves further upward toward the geometric center of the bearing, and the eccentricity of the shaft neck decreases. Furthermore, the upward movement of the shaft neck increases the gap between the shaft neck and the bearing, increasing the thickness of the air film below the shaft neck, resulting in a simultaneous decrease in the static stiffness and static load-bearing capacity of the air film. At the same time, the reduced eccentricity makes the wedge-shaped convergence gap less obvious, weakening the dynamic pressure effect of the air film and simultaneously reducing the lift generated by the dynamic pressure effect. In this case, when the rotor is subjected to external disturbances, the journal is prone to significant deflection, making it difficult to return to equilibrium, causing sustained oscillation and even shaft instability or even friction. In other words, when the rotor rotates at high speed, the hydrostatic air bearing is significantly affected by the dynamic pressure effect, which can cause shaft instability and restrict its application in small and medium-sized centrifugal compressors.

[0031] It can be understood that the geometric center of the bearing is also the symmetry center of the bearing. The closer the journal is to the geometric center of the bearing, the smaller the eccentricity of the journal; correspondingly, the farther the journal is from the geometric center of the bearing, the greater the eccentricity of the journal.

[0032] The present application provides a bearing and a compressor, which can increase the stability of the bearing.

[0033] In a first aspect, the present application provides a bearing.

[0034] Combine Figure 1 、 Figure 2 and Figure 5 As shown, the bearing provided in this application includes a bearing sleeve 1, a porous medium layer 2 and a journal 4.

[0035] The bearing sleeve 1 is provided with an air supply hole 11 .

[0036] The porous medium layer 2 is disposed within the bearing sleeve 1. The porous medium layer 2 and the bearing sleeve 1 enclose an air supply cavity 3 that communicates with the air supply hole 11. The radial cross-section of the inner wall of the porous medium layer 2 includes an upper profile 21 and a lower profile 22, with the lower profile 22 located below the upper profile 21 in the direction of gravity.

[0037] The journal 4 is rotatably disposed in the porous medium layer 2 .

[0038] In the case where the journal 4 is suspended, a first movable gap 51 is formed between the upper profile 21 and the journal 4, and a second movable gap 52 is formed between the lower profile 22 and the journal 4. Along the rotation direction of the journal 4, the first movable gap 51 includes at least a first convergent gap 511 with a gradually decreasing thickness, and the second movable gap 52 includes at least a second convergent gap 521 with a gradually decreasing thickness. The thickness of the convergent gap refers to: the distance between the outer wall surface of the journal 4 and the inner wall surface of the porous medium layer 2 along the radial direction of the journal 4. Figure 1 As shown, when the journal 4 is suspended, along the rotation direction of the journal 4, there is a second movable gap 52 between the lower profile 22 and the journal 4, the thickness of which first decreases and then increases, wherein the portion of the second movable gap 52 with gradually decreasing thickness is the second convergent gap 521; similarly, there is a first movable gap 51 between the upper profile 21 and the journal 4, the thickness of which first decreases and then increases, wherein the portion of the first movable gap 51 with gradually decreasing thickness is the first convergent gap 511. The inner wall surface refers to the surface of the porous medium layer 2 close to the journal 4. During the operation of the bearing, high-pressure gas is continuously introduced into the air supply hole 11, that is, when the journal 4 is not rotating, rotating at a low speed, or rotating at a high speed, it is necessary to continuously introduce high-pressure gas into the air supply hole 11.

[0039] When the above technical solution is adopted, the bearing provided by the present application forms a gradually decreasing thickness convergent gap between the upper profile 21 and the journal 4, and between the lower profile 22 and the journal 4, that is, two convergent gaps are formed on the upper and lower sides of the journal 4. An external high-pressure gas source enters the gas supply cavity 3 through the gas supply hole 11 and penetrates into the porous medium layer 2, forming a pressure gas film 5 between the porous medium layer 2 and the journal 4.

[0040] Combine Figure 1As shown, external high-pressure gas enters the air supply cavity 3 through the air supply hole 11. Under the action of pressure, it penetrates the porous medium layer 2, forming a pressure film 5 between the journal 4 and the porous medium layer 2. The journal 4 is close to the bottom of the porous medium layer 2 due to gravity. The thickness of the pressure film 5 between the journal 4 and the bottom of the porous medium layer 2 is relatively small, while the thickness of the pressure film 5 between the journal 4 and the top of the porous medium layer 2 is relatively large. The stiffness of the pressure film 5 increases as the thickness decreases. The static stiffness of the pressure film 5 located below the journal 4 is greater than that located above the journal 4. A pressure differential is generated between the upper and lower sides of the journal 4, causing the journal 4 to levitate. When the rotor rotates at low speed, the pressure film 5 is less affected by the dynamic pressure effect, and the bearing exhibits the characteristics of a pure static pressure air bearing.

[0041] As the rotor speed increases, the pressure film 5 is increasingly affected by the dynamic pressure effect, and the dynamic pressure effect of the bearing cannot be ignored. The bearing more often exhibits the characteristics of a dynamic pressure air bearing. Since the journal 4 is close to the bottom of the porous medium layer 2 due to gravity, the second convergence gap 521 located on the lower side of the journal 4 is more obvious than the first convergence gap 511 located on the upper side of the journal 4. The pressure generated in the second convergence gap 521 by the dynamic pressure effect is higher than the pressure generated in the first convergence gap 511. Therefore, the journal 4 is lifted up by the dynamic pressure effect, for example, Figure 1 The status shown changes to Figure 2 In the state shown, the journal 4 is close to the geometric center o of the bearing, reducing the eccentricity of the journal 4. As the eccentricity decreases, the first convergence gap 511 becomes more and more obvious, and the pressure generated by the dynamic pressure effect of the air film also increases. At the same time, the second convergence gap 521 becomes less and less obvious, and the pressure generated by the dynamic pressure effect of the air film decreases. The combination of these two stabilizes the center of the journal 4 within a certain range, preventing further reduction in the eccentricity of the journal 4 and further reduction in the static and dynamic stiffness of the pressure air film 5. The stable air film stiffness increases the anti-disturbance ability of the journal 4 and improves the stability of the bearing.

[0042] An air film is generated in the first convergence gap 511 and the second convergence gap 521. The pressure of the air film is relatively large. The pressure on the inward side of the air film acts on the shaft neck 4, causing the shaft neck 4 to float in the air supply cavity 3; the pressure on the outward side of the air film acts on the inner wall surface of the porous medium layer 2. During the operation of the bearing, air is continuously supplied to the air supply hole 11, so that the gas forming the air film will not flow out through the porous medium layer 2, ensuring that there is enough gas in the air supply cavity 3 to form a dynamic pressure air film.

[0043] Among them, the geometric center of the bearing is also the symmetry center of the bearing, that is, Figure 1 and attached Figure 2 The point o in the figure is the geometric center of the bearing and is also the symmetry center of the bearing sleeve 1 and the porous medium layer 2.

[0044] The inner wall surface of the porous medium layer 2 can be arranged in at least the following two ways: In some embodiments, Figure 2 As shown, the upper profile line 21 and the lower profile line 22 are symmetrically arranged arcs, the symmetry line between the upper profile line 21 and the lower profile line 22 is the first symmetry line, the center of the circle corresponding to the upper profile line 21 is located on the side of the first symmetry line close to the lower profile line 22, and the center of the circle corresponding to the lower profile line 22 is located on the side of the first symmetry line close to the upper profile line 21. Figure 2 Here, p1 is the center of the circle corresponding to the upper profile line 21, and p2 is the center of the circle corresponding to the lower profile line 22. In other words, the centers of the circles corresponding to the upper profile line 21 and the lower profile line 22 are symmetrically offset to the upper and lower sides of the symmetry center.

[0045] In this way, the upper mold line 21 and the lower mold line 22 are connected to form Figure 2 The approximately elliptical shape shown can form a gap between the upper profile 21 and the journal 4, and between the lower profile 22 and the journal 4, whose thickness first decreases and then increases, so that the upper profile 21 and the journal 4, and the lower profile 22 and the journal 4, each contain a convergence gap with a gradually decreasing thickness. When the rotor speed is high, high-pressure gas is continuously introduced into the air supply hole 11, and at the same time, the dynamic pressure effect generated by the first convergence gap 511 becomes increasingly stronger. The pressure generated presses the journal 4 downward, preventing the eccentricity of the journal 4 from further decreasing, maintaining the air film stiffness of the bearing within a certain range, improving the anti-disturbance ability of the journal 4, and improving the stability of the bearing. Among them, the first convergence gap 511 refers to the convergence gap located between the upper profile 21 and the journal 4, and the second convergence gap 521 refers to the convergence gap located between the lower profile 22 and the journal 4.

[0046] In some embodiments, combined Figure 3 As shown, the cross section of the inner wall of the porous medium layer 2 in the radial direction is elliptical, and the length of the symmetry axis of the ellipse along the horizontal direction is greater than the length of the symmetry axis of the ellipse along the vertical direction. Figure 3 The elliptical shape shown can also form gaps between the upper profile 21 and the journal 4, and between the lower profile 22 and the journal 4, that initially decrease in thickness and then increase in thickness, resulting in a convergent gap between the upper profile 21 and the journal 4, and between the lower profile 22 and the journal 4, with gradually decreasing thickness. When the rotor rotates at high speeds, high-pressure gas is continuously introduced into the air supply hole 11, and the dynamic pressure effect generated by the first convergent gap 511 becomes increasingly stronger. The pressure generated presses the journal 4 downward, preventing the eccentricity of the journal 4 from further decreasing. This maintains the bearing's air film stiffness within a certain range, improves the journal 4's anti-disturbance capability, and enhances the bearing's stability.

[0047] In some embodiments, combined Figure 4 As shown, the symmetry axes of the figure formed by the upper mold line 21 and the lower mold line 22 in the horizontal and vertical directions are the first symmetry axes l 1 and the second axis of symmetry l 2 . Among them, the preload coefficient m=(R L -R S ) / (R L -R j ) ranges from 0.2 to 0.5, R L is the radius of the first axis of symmetry, R S is the radius of the second axis of symmetry, R j is the radius of the journal 4. The preload coefficient m characterizes the relationship between the radius of the first axis of symmetry, the radius of the second axis of symmetry, and the radius of the journal 4. When the preload coefficient m approaches 0, it means that the closer the radius of the first axis of symmetry and the radius of the second axis of symmetry are, the closer the inner wall surface is to a complete circle. At this time, the bearing will degenerate into a conventional hydrostatic cyclone floating bearing, and only a convergent gap can be formed between the inner wall surface of the porous medium layer 2 and the journal 4, and the stability is poor; when the preload coefficient m approaches 1, the closer the radius of the second axis of symmetry is to the radius of the journal 4, the insufficient vertical clearance of the bearing, and the easy occurrence of friction between the journal 4 and the bearing. By setting the value of the preload coefficient m within the range of 0.2~0.5, it is ensured that there is a suitable gap between the journal 4 and the inner wall surface of the porous medium layer 2, and the stability of the bearing is also improved.

[0048] In some embodiments, combined Figure 1 As shown, the porous medium layer 2 includes an upper porous medium layer 23 and a lower porous medium layer 24, with the lower porous medium layer 24 located below the upper porous medium layer 23 in the direction of gravity. The porosity of the upper porous medium layer 23 is less than that of the lower porous medium layer 24. With this arrangement, the porosity of the upper porous medium layer 23 is less than that of the lower porous medium layer 24, making the upper porous medium layer 23 denser. The resistance encountered by gas flowing through the upper porous medium layer 23 is greater than the resistance encountered through the lower porous medium layer 24, and the gas flow rate penetrating through the upper porous medium layer 23 is less than the gas flow rate penetrating through the lower porous medium layer 24. This can increase the pressure difference between the air films on the upper and lower sides of the journal 4 during the bearing's static pressure operating phase, making the journal 4 more buoyant and increasing the bearing's load-bearing capacity. The bearing's static pressure operating phase refers to the phase when the rotor is not rotating or rotating at a low speed.

[0049] In some embodiments, the porosity of both the upper porous medium layer 23 and the lower porous medium layer 24 ranges from 10% to 35%. For example, the porosity of the upper porous medium layer 23 can be 10%, 15%, 20%, 23%, 25%, 27%, 30%, or 35%. The porosity of the lower porous medium layer 24 can be 15%, 20%, 23%, 25%, 27%, or 30%. The porosity of the upper porous medium layer 23 and the lower porous medium layer 24 can be flexibly set according to actual needs. Porosity directly affects gas permeability, air film uniformity, and bearing capacity. Higher porosity increases gas permeability, but too high a porosity may lead to uneven air film pressure distribution. Lower porosity increases material strength but reduces gas permeability, reducing the amount of air passing through the porous medium layer 2 and thus reducing the bearing's bearing capacity. By limiting the porosity of the upper porous medium layer 23 and the lower porous medium layer 24 to a range of 10% to 35%, a uniformly distributed pressure gas film 5 can be formed between the porous medium layer 2 and the journal 4 .

[0050] In some embodiments, the ratio of the porosity of the upper porous medium layer 23 to the porosity of the lower porous medium layer 24 ranges from 0.4 to 0.6. For example, the ratio of the porosity of the upper porous medium layer 23 to the porosity of the lower porous medium layer 24 ranges from 0.4, 0.43, 0.5, 0.55, or 0.6. The lower porous medium layer 24 has a greater porosity, and the amount of air that seeps through it is also greater, making it easier for the journal 4 to be lifted by the bearing. If the porosity ratio is too small, it means that the porosity of the upper porous medium layer 23 is too small, and the amount of air that seeps through it is also small. Such a small amount of air may not be able to effectively bear the unbalanced force and disturbance force generated when the journal 4 rotates. If the porosity ratio is too large, it means that the porosity of the upper porous medium layer 23 and the lower porous medium layer 24 tend to be consistent, and the supporting force of the journal 4 cannot be effectively improved.

[0051] In some embodiments, the porous medium layer 2 is made of one or more of porous metal, porous carbon, and porous ceramic. Porous metals include sintered brass, stainless steel, nickel-based alloys, titanium, and titanium alloys. Porous ceramics include aluminum oxide or silicon carbide.

[0052] Porous metal, porous carbon and porous ceramics have excellent permeability and rigidity, which can allow gas to evenly penetrate into the porous medium layer 2 , thereby improving the uniformity and stability of the gas film between the porous medium layer 2 and the journal 4 .

[0053] In some embodiments, the cross section of the outer wall of the porous medium layer 2 in the radial direction is circular, so as to avoid the risk of friction.

[0054] In a second aspect, the present application provides a compressor.

[0055] The compressor provided in the present application includes the bearing of any one of the above embodiments.

[0056] When the above-mentioned technical solution is adopted, in the compressor provided by the present application, when the rotor speed is high, the convergence gap on the upper side of the journal 4 becomes more and more obvious, and the pressure generated by the air film dynamic pressure effect becomes larger and larger. The dynamic pressure effect generated by the first convergence gap 511 becomes stronger and stronger, and the pressure generated squeezes the journal 4 downward, preventing the eccentricity of the journal 4 from further decreasing, so that the air film stiffness of the bearing is maintained within a certain range, thereby improving the anti-disturbance ability of the journal 4 and the stability of the bearing, which is conducive to ensuring the continuous and reliable operation of the compressor.

[0057] The compressor further includes a rotor, and a journal 4 is connected to the rotor to support the rotor.

[0058] It should be noted that the above preferred embodiments are only used to illustrate the principles of this application and are not intended to limit the scope of protection of this application. Without departing from the principles of this application, those skilled in the art may adjust the above settings so that this application can be applied to more specific application scenarios.

[0059] Those skilled in the art will appreciate that, although some embodiments herein include certain features included in other embodiments but not other features, combinations of features from different embodiments are intended to be within the scope of this application and to form different embodiments. For example, in the claims of this application, any of the claimed embodiments may be used in any combination.

[0060] Thus far, the technical solutions of the present application have been described in conjunction with the preferred embodiments shown in the accompanying drawings. However, it is readily understood by those skilled in the art that the scope of protection of the present application is obviously not limited to these specific embodiments. Without departing from the principles of the present application, those skilled in the art may make equivalent changes or substitutions to the relevant technical features, and the technical solutions after such changes or substitutions will fall within the scope of protection of the present application.

Claims

1. A bearing, characterized in that: The bearing comprises: The bearing sleeve (1) is provided with an air supply hole (11); A porous medium layer (2) is arranged in the bearing sleeve (1) and encloses the bearing sleeve (1) to form an air supply cavity (3) connected to the air supply hole (11); a radial cross-section of the inner wall surface of the porous medium layer (2) includes an upper molded line (21) and a lower molded line (22), and the lower molded line (22) is located below the upper molded line (21) along the direction of gravity; A journal (4) is rotatably disposed in the porous medium layer (2); when the journal (4) is suspended, a first movable gap (51) is formed between the upper profile (21) and the journal (4), and a second movable gap (52) is formed between the lower profile (22) and the journal (4); Wherein, along the rotation direction of the journal (4), the first movable gap (51) includes at least a first convergent gap (511) with a gradually decreasing thickness, and the second movable gap (52) includes at least a second convergent gap (521) with a gradually decreasing thickness; The porous medium layer (2) comprises an upper porous medium layer (23) and a lower porous medium layer (24), wherein the lower porous medium layer (24) is located below the upper porous medium layer (23) along the direction of gravity; The porosity of the upper porous medium layer (23) is smaller than the porosity of the lower porous medium layer (24).

2. The bearing according to claim 1, characterized in that The upper mold line (21) and the lower mold line (22) are symmetrically arranged arcs, and the symmetry line between the upper mold line (21) and the lower mold line (22) is a first symmetry line; The center of the circle corresponding to the upper molded line (21) is located on the side of the first symmetry line close to the lower molded line (22), and the center of the circle corresponding to the lower molded line (22) is located on the side of the first symmetry line close to the upper molded line (21).

3. The bearing according to claim 1, characterized in that The cross-section of the inner wall surface of the porous medium layer (2) in the radial direction is elliptical, and the length of the symmetry axis of the ellipse along the horizontal direction is greater than the length of the symmetry axis of the ellipse along the vertical direction.

4. The bearing according to claim 2 or 3, characterized in that: The symmetry axes of the figure enclosed by the upper mold line (21) and the lower mold line (22) in the horizontal and vertical directions are respectively the first symmetry axis and the second symmetry axis; Among them, (R L -R S ) / (R L -R j ) ranges from 0.2 to 0.5, R L is the radius of the first symmetry axis, R S is the radius of the second symmetry axis, R j is the radius of the journal.

5. The bearing according to claim 1, wherein: The porosity of the upper porous medium layer (23) and the lower porous medium layer (24) both ranges from 10% to 35%.

6. The bearing according to claim 1, characterized in that The ratio of the porosity of the upper porous medium layer (23) to the porosity of the lower porous medium layer (24) is in the range of 0.4 to 0.

6.

7. The bearing according to claim 1, characterized in that The material of the porous medium layer (2) includes one or more of porous metal, porous carbon and porous ceramic.

8. The bearing according to any one of claims 1 to 3, characterized in that The cross-section of the outer wall surface of the porous medium layer (2) in the radial direction is circular.

9. A compressor, characterized in that: The compressor includes the bearing according to any one of claims 1 to 8.

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