A dynamic pressure air radial bearing employing a double-layer circumferential variable stiffness wave foil

Abstract

The present application belongs to the field of foil type dynamic pressure air bearing, and particularly relates to a dynamic pressure air radial bearing adopting double-layer circumferential variable stiffness wave foils, comprising: a bearing seat, a plurality of foil groups, wherein the foil group comprises: a flat foil which is in the shape of a whole circular arc and is coaxially arranged with the bearing seat; a wave foil which is in the shape of a whole circular arc and is arranged between the inner wall of the bearing seat and the outer wall of the flat foil; the wave foil comprises: an inner layer wave foil and an outer layer wave foil, the inner layer wave foil is arranged on the side close to the flat foil, and the outer layer wave foil is arranged on the side close to the inner wall of the bearing seat; the inner layer wave foil is prepared from super-elastic material, and the outer layer wave foil is prepared from elastic material; the dynamic pressure air radial bearing adopting double-layer circumferential variable stiffness wave foils has the advantages of high load capacity and strong stability during high-speed operation.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of foil dynamic pressure air bearing, in particular to a dynamic pressure air radial bearing adopting a double-layer circumferential variable stiffness wave foil. BACKGROUND

[0002] A gas bearing is a kind of sliding bearing using gas as lubricant. Compared with traditional liquid lubrication bearing and rolling bearing, the gas bearing has the characteristics of high rotating speed, low noise, no pollution, high reliability, long service life, low friction and wear, wide temperature range and high durability. The working principle of the gas bearing is basically the same as that of the traditional oil lubrication sliding bearing, that is, the viscosity of the gas is used to improve the pressure in the bearing gap to overcome the gravity of the object and make the object float. According to the working principle, the gas bearing can be divided into two types: static pressure gas bearing and dynamic pressure gas bearing. The static pressure gas bearing uses an external gas source to provide high pressure gas, which requires an additional gas supply system, increasing the complexity of the overall system. At the same time, the gas supply system compresses the high pressure gas, reducing the economy of the system and limiting the application range of the static pressure gas bearing. The dynamic pressure gas bearing uses the gas film pressure generated by the viscous gas in the bearing wedge-shaped gap when the shaft rotates to support the load. Its biggest feature is that it does not need an additional gas supply system, and the structure is simple, which expands the application field of the gas bearing, especially when applied to air compressors, it can realize the high efficiency operation of the compressor. According to whether the bearing surface is deformed, the dynamic pressure gas bearing can be divided into rigid surface gas bearing and flexible surface gas bearing. Among them, the rigid surface gas bearing has high requirements for assembly precision and machining precision, and it is difficult to install and center, the bearing running stability is low, and the instability phenomenon is easy to occur; the flexible surface gas bearing, i.e. foil gas bearing, generally uses metal foil as the bearing surface, and its flexible surface is beneficial to the formation of the gas film gap; when the shaft load changes, the flexible surface gas bearing will adaptively deform to adjust the gas film gap, and establish a gas film thickness matching the load, so that the bearing has good high speed stability. Therefore, the flexible surface gas bearing is widely used in high speed rotating machinery. At present, with the wide application of turboexpander, micro gas turbine and other high speed rotating machinery, the wave foil dynamic pressure air bearing has great application advantages in the support of high speed rotating machinery because it does not need a lubricating oil system, has a simple structure and higher efficiency than traditional lubricating oil bearings at high speed. At present, the air circulation machine of the environmental control system of the military and civilian aircraft and land vehicles in the United States and other developed countries uses a wave foil gas bearing.

[0003] Generally, the wave foil type dynamic pressure air radial bearing is composed of a bearing seat, a wave foil and a flat foil. The wave foil is used to provide support stiffness and damping, the top foil is used to provide a friction surface between the bearing and the gas film, and the bearing seat provides mounting positions for the wave foil and the top foil. The working principle is that an uneven wedge-shaped gap is formed along the circumference by the eccentricity of the rotor, the gas is brought into the wedge-shaped gap by means of the wedge-shaped gap and two opposite high-speed sliding surfaces, and the pressure difference is formed by using the dynamic pressure effect of the gas, thereby generating a bearing capacity.

[0004] At present, with the increasingly wide use of the wave foil type dynamic pressure air radial bearing, higher requirements are put forward for the bearing capacity and stability of the wave foil type gas bearing, and it is urgently hoped to obtain a wave foil type dynamic pressure air radial bearing with higher bearing capacity and stability. SUMMARY

[0005] The purpose of the present application is to improve the bearing capacity and stability of the foil dynamic pressure air radial bearing at high speed, and to provide a dynamic pressure air radial bearing with double-layer circumferential variable stiffness wave foils.

[0006] Therefore, the present application provides a dynamic pressure air radial bearing with double-layer circumferential variable stiffness wave foils, which comprises:

[0007] A bearing seat having a shell inner wall for enclosing a circular hollow inner cavity for accommodating a rotor;

[0008] A plurality of foil groups arranged in the circular hollow inner cavity, one end of the foil group being a fixed end fixed to the bearing seat, the other end being a free end, and the plurality of foil groups being arranged in the circular hollow inner cavity in a clockwise or counterclockwise ring shape with the fixed end as the head and the free end as the tail;

[0009] The foil group comprises:

[0010] A flat foil in the shape of a circular arc, the flat foil being coaxially arranged with the bearing seat;

[0011] A wave foil in the shape of a circular arc, the wave foil being arranged between the inner wall of the bearing seat and the outer wall of the flat foil;

[0012] The wave foil comprises:

[0013] An inner layer wave foil and an outer layer wave foil, the inner layer wave foil being arranged on the side close to the flat foil, and the outer layer wave foil being arranged on the side close to the inner wall of the bearing seat, the inner layer wave foil being made of super-elastic material, and the outer layer wave foil being made of elastic material.

[0014] Further, the inner layer wave foil is provided with inner wave protrusions and inner arc segments, which are arranged alternately along the circumferential direction of the bearing seat;

[0015] Correspondingly, the outer layer wave foil is provided with outer wave protrusions and outer arc segments, which are arranged alternately along the circumferential direction of the bearing seat;

[0016] The inner layer wave foil and the outer layer wave foil are stacked, and the inner wave protrusions and the outer wave protrusions are arranged correspondingly to form a preset gap therebetween; the inner arc segments and the outer arc segments are arranged correspondingly, and the outer wall of the inner arc segment and the inner wall of the outer arc segment are connected in abutment.

[0017] Further, the inner wave protrusions and the outer wave protrusions are arranged in parallel, and the width of the preset gap is a constant value.

[0018] Further, the wave crest of the inner wave protrusion is in contact with the outer wall of the flat foil; and the outer wall of the outer arc segment is connected in abutment with the inner wall of the bearing seat.

[0019] Further, the inner wave protrusions on the inner layer wave foil have shapes that vary along the circumferential direction of the bearing; correspondingly, the outer wave protrusions on the outer layer wave foil also have shapes that vary along the circumferential direction of the bearing.

[0020] Further, in the circumferential direction of the bearing, the inner wave protrusions and the outer wave protrusions are in the shape of a half ellipse.

[0021] Further, the dynamic pressure air radial bearing comprises two foil groups, i.e. a first foil group and a second foil group, the first foil group is located at the upper part of the bearing seat, the inner wave protrusions and the outer wave protrusions located in the middle are located directly above the central axis of the bearing seat, and the remaining inner wave protrusions and outer wave protrusions are symmetrically arranged along the circumferential direction of the bearing with the inner wave protrusions and the outer wave protrusions located in the middle as the center;

[0022] Correspondingly, the second foil group is located at the lower part of the bearing seat, the inner wave protrusions and the outer wave protrusions located in the middle are located directly below the central axis of the bearing seat, and the remaining inner wave protrusions and outer wave protrusions are symmetrically arranged along the circumferential direction of the bearing with the inner wave protrusions and the outer wave protrusions located in the middle as the center.

[0023] Further, from the center of the inner layer wave foil and the outer layer wave foil to both sides, the ratio of the long radius to the short radius of the inner wave protrusions and the outer wave protrusions gradually decreases.

[0024] Further, the dynamic pressure air radial bearing further comprises:

[0025] A positioning plate is formed by extending radially outward from the end edge of the bearing seat, and the positioning plate is in the form of an annular structure arranged around the outer wall of the bearing seat;

[0026] A plurality of locking screws are used to fix the positioning plate to the bearing seat;

[0027] A connecting hook is arranged at the fixed end of the foil group, and a connecting groove is arranged on the bearing seat, and the connecting hook is inserted and hooked on the connecting groove.

[0028] Further, the preparation process of the dynamic pressure air radial bearing comprises the following steps:

[0029] S1, designing and processing the molds of the outer layer wave foil and the inner layer wave foil;

[0030] S2, processing the corrugated structures in the outer layer wave foil and the inner layer wave foil respectively by stamping the metal sheets based on the two molds;

[0031] S3, bending the flat foil, the inner layer wave foil and the outer layer wave foil into circular arcs as a whole respectively, and bending one end of each foil into a set hook to obtain the connecting hook;

[0032] S4, processing the connecting groove on the bearing seat;

[0033] S5, arranging the outer layer wave foil, the inner layer wave foil and the flat foil in the order of outer to inner along the radial direction to form a foil group, connecting the two foil groups to the bearing seat through the connecting hook, then connecting the positioning plate to the bearing seat through the locking screw, and completing the assembly of the whole bearing.

[0034] The dynamic pressure air radial bearing has the following advantages:

[0035] First, the inner layer wave foil prepared by using the super-elastic material in the dynamic pressure air radial bearing can effectively suppress the vibration of the rotor and improve the stability of the bearing under high-speed working conditions by consuming the vibration energy of the rotor through the high damping characteristics of the super-elastic stage.

[0036] Second, the dynamic pressure air radial bearing fully considers the actual load environment of the bearing, and realizes the radial supporting stiffness varying along the circumference by changing the shape of the wave foil along the circumference, wherein the wave foil structure in the high gas film pressure (high load) area has higher radial supporting stiffness, which can effectively improve the carrying capacity; at the same time, the radial supporting stiffness of the bearing wave foil designed by the application is consistent with the distribution law of the gas film pressure along the circumference of the bearing, which can also effectively improve the carrying capacity of the bearing.

[0037] Thirdly, the dynamic pressure air radial bearing has two layers of wave foil structures distributed along the radial direction, namely, an inner layer of wave foils and an outer layer of wave foils, and the two layers of wave foils are deformed together to provide support under a high load condition, so that the bearing capacity is effectively improved; only the inner layer of wave foils is deformed to provide support under a light load condition, so that the bearing capacity of the bearing under a heavy load condition is effectively improved.

[0038] Fourthly, the dynamic pressure air radial bearing adopts a method of dividing the foils into two groups along the circumferential direction, breaks the continuity of the supporting air film along the circumferential direction, weakens the radial cross support stiffness of the bearing, thereby inhibiting the subsynchronous amplitude of the rotor and improving the running stability of the bearing, and improving the anti-disturbance ability of the bearing.

[0039] In summary, the dynamic pressure air radial bearing adopting the double-layer circumferential variable stiffness wave foils has the advantages of high bearing capacity and strong stability during high-speed operation. BRIEF DESCRIPTION OF DRAWINGS

[0040] Figure 1 is a stress-strain curve of a super-elastic material;

[0041] Figure 2 is a front view structural schematic diagram of the dynamic pressure air radial bearing;

[0042] Figure 3 is a side view structural schematic diagram of the dynamic pressure air radial bearing;

[0043] Figure 4 is Figure 3 is a local structure enlarged schematic diagram of a P1 area in the figure;

[0044] Figure 5 is a detail schematic diagram of the shape of the wave-shaped protrusions in the wave foils changing along the circumferential direction;

[0045] The mark in the figure represents:

[0046] 1, foil group; 1a, first foil group; 1b, second foil group; 101, flat foil; 102, wave foil; 1021, inner layer of wave foils; 10211, inner wave-shaped protrusion; 10212, inner arc-shaped section; 1022, outer layer of wave foils; 10221, outer wave-shaped protrusion; 10222, outer arc-shaped section; 1023, preset gap; 103, fixed end; 1031, connecting hook; 104, free end; 2, bearing seat; 201, connecting groove; 3, locking screw; 4, positioning plate. DETAILED DESCRIPTION

[0047] In the description of the application, it should be explained that the terms used herein are only for describing the specific embodiments, and are not intended to limit the exemplary embodiments according to the application. In order to facilitate the description, the size of each part shown in the drawings is not drawn according to the actual proportional relationship. The technology, method and equipment known to those skilled in the related art can not be discussed in detail, but should be regarded as part of the authorized description. In all examples shown and discussed here, any specific value should be interpreted as only exemplary, not as a limitation. Therefore, other examples of exemplary embodiments can have different values. It should be noted that similar reference numbers and letters represent similar items in the following drawings, so once an item is defined in one drawing, it does not need to be further discussed in subsequent drawings.

[0048] In the description of the application, it should be explained that the terms used herein are only for describing the specific embodiments, and are not intended to limit the exemplary embodiments according to the application. In order to facilitate the description, the size of each part shown in the drawings is not drawn according to the actual proportional relationship. The technology, method and equipment known to those skilled in the related art can not be discussed in detail, but should be regarded as part of the authorized description. In all examples shown and discussed here, any specific value should be interpreted as only exemplary, not as a limitation. Therefore, other examples of exemplary embodiments can have different values. It should be noted that similar reference numbers and letters represent similar items in the following drawings, so once an item is defined in one drawing, it does not need to be further discussed in subsequent drawings.

[0049] It should be noted that the terms "first", "second" and the like in the specification and claims of the application are used to distinguish similar objects, and are not intended to describe a specific order or sequence. It should be understood that the data used in this way can be exchanged under appropriate circumstances, so that the embodiments of the application can be implemented in an order other than that illustrated or described herein, and the objects distinguished by "first", "second" and the like are usually a class, not limited to the number of objects, for example, the first object can be one or more. In addition, "and / or" in the specification and claims indicates at least one of the connected objects, and the character " / ", generally indicates that the front and rear associated objects are "or" relationship.

[0050] It should be noted that in the description of the application, the orientation terms such as "front, rear, upper, lower, left, right", "circumferential" and "radial" and the like indicated by the orientation or position relationship shown in the drawings are generally based on the orientation or position relationship shown in the drawings, only for the convenience of describing the application and simplifying the description, without the opposite description, these orientation terms do not indicate and imply that the indicated device or element must have a specific orientation or be constructed and operated in a specific orientation, therefore, it cannot be understood as a limitation on the scope of protection of the application; The orientation terms "inner" and "outer" refer to the inner and outer of the profile of each part itself.

[0051] It is to be understood that the terminology "including", "containing" or any other variation thereof herein is intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements is not necessarily limited to those elements, but can include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element preceded by "comprises a" does not, without more constraints, preclude the existence of additional identical elements in the process, method, article, or apparatus that includes the element. In addition, it should be noted that the scope of the methods and apparatus of the embodiments herein is not limited to performing functions in the order shown or discussed, but can include performing functions in substantially simultaneous, or in reverse order, for example, the described methods can be performed in a different order than described, and various steps can be added, omitted, or combined, in addition, features described with respect to certain examples can be combined in other examples.

[0052] As shown in Figures 2 to 5 , a dynamic pressure air radial bearing with double-layer circumferential variable stiffness wave foils, comprising:

[0053] a bearing housing 2 having a shell inner wall for enclosing a circular hollow inner cavity accommodating a rotor;

[0054] a plurality of foil groups 1 arranged in the circular hollow inner cavity, one end of the foil group 1 being a fixed end 103 fixed to the bearing housing 2, and the other end being a free end 104.

[0055] As some embodiments of the present application, the dynamic pressure air radial bearing comprises 2-4 foil groups 1, each foil group 1 being arranged in the circular hollow inner cavity in a ring shape as a whole in the clockwise or counterclockwise direction with the fixed end 103 as the head and the free end 104 as the tail.

[0056] Preferably, as shown in Figure 3 , the dynamic pressure air radial bearing comprises 2 foil groups 1, namely a first foil group 1a and a second foil group 1b, wherein the first foil group 1a is located at the upper part of the bearing housing 2; the second foil group 1b is located at the lower part of the bearing housing 2; the first foil group 1a and the second foil group 1b are arranged in the circular hollow inner cavity in a ring shape as a whole in the clockwise or counterclockwise direction.

[0057] In the dynamic pressure air radial bearing, the foil structure composed of the two groups of foil groups 1 arranged in the circumferential direction can effectively break the continuity of the gas film in the circumferential direction, weaken the radial cross-supporting stiffness of the gas film, effectively suppress the vibration of the rotor, and improve the running stability of the bearing.

[0058] Further, the foil group 1 comprises:

[0059] A flat foil 101, which is in the shape of a circular arc, is arranged in the circular hollow cavity, and the flat foil 101 is coaxially arranged with the bearing seat 2;

[0060] A wave foil 102, which is in the shape of a circular arc, is arranged between the inner wall of the bearing seat 2 and the outer wall of the flat foil 101.

[0061] Further, the wave foil 102 comprises:

[0062] An inner layer wave foil 1021 and an outer layer wave foil 1022, the inner layer wave foil 1021 is arranged on the side close to the flat foil 101, and the outer layer wave foil 1022 is arranged on the side close to the inner wall of the bearing seat 2, the inner layer wave foil 1021 is made of super-elastic material, and the outer layer wave foil 1022 is made of ordinary elastic material.

[0063] Among them, the super-elastic material of the application refers to the material that produces a strain far exceeding the elastic limit strain under the action of external force, and the strain can recover to the original state when unloading; the ordinary elastic material refers to the material that can recover to its original state after being deformed under external force. From the perspective of material physical properties, the biggest difference between super-elastic material and elastic material is that the deformation ability and recovery ability of super-elastic material are higher. Compared with super-elastic material, although ordinary elastic material can also recover to the original shape, its deformation range is relatively small and slow; while the deformation ability and recovery ability of super-elastic material are very high, which is not limited by material properties and shape, and has good toughness.

[0064] As some examples of the application, the inner layer wave foil 1021 can be made of super-elastic materials such as nickel-titanium super-elastic alloy, elastic fiber composite material, carbon fiber reinforced ceramic (CFCC), etc.

[0065] Preferably, the inner layer wave foil 1021 is made of nickel-titanium super-elastic alloy.

[0066] As some examples of the application, the outer layer wave foil 1022 can be made of one or more ordinary elastic materials such as rubber, polyurethane, propylene-based elastomer, polyester elastomer, and metal alloy, such as copper alloy, high-temperature alloy, etc.

[0067] Preferably, the outer layer wave foil 1022 is made of copper alloy, and / or, nickel-based high-temperature alloy, and / or, iron-based high-temperature alloy, and / or, cobalt-based high-temperature alloy.

[0068] Preferably, the inner wave foil 1021 is provided with inner wave protrusions 10211 and inner arc segments 10212, which are arranged alternately along the circumferential direction of the bearing housing 2.

[0069] Correspondingly, the outer wave foil 1022 is provided with outer wave protrusions 10221 and outer arc segments 10222, which are arranged alternately along the circumferential direction of the bearing housing 2.

[0070] The inner wave foil 1021 and the outer wave foil 1022 are stacked, and the inner wave protrusions 10211 and the outer wave protrusions 10221 are arranged correspondingly, forming a preset gap 1023 between the inner wave protrusions 10211 and the outer wave protrusions 10221; the inner arc segments 10212 and the outer arc segments 10222 are arranged correspondingly, and the outer wall of the inner arc segment 10212 and the inner wall of the outer arc segment 10222 are connected in abutment.

[0071] More preferably, the inner wave protrusions 10211 and the outer wave protrusions 10221 are arranged in parallel, so that the width of the preset gap 1023 is a constant value.

[0072] Further, the wave crest of the inner wave protrusion 10211 is in contact with the outer wall of the flat foil 101, so as to provide support for the flat foil 101; the outer wall of the outer arc segment 10222 is connected in abutment with the inner wall of the bearing housing 2, so as to provide support for the wave foil 102.

[0073] In the dynamic pressure air radial bearing, the inner wave foil 1021 made of super-elastic material has a stress-strain curve as shown in the figure. Figure 1 When the stress-strain value of the inner wave foil 1021 enters the super-elastic stage under the influence of high load or sudden load increase, and returns to the elastic stage after the load decreases or the sudden load disappears, the area contained in the stress-strain cycle curve experienced by the inner wave foil 1021 made of super-elastic material is the vibration energy consumed by the unit volume of super-elastic material. The dynamic pressure air radial bearing inevitably bears sudden impact load when running at high speed. The consumption of vibration energy by the inner wave foil 1021 made of super-elastic material can improve the adaptability of the designed bearing to sudden impact load, thereby improving the stability of the bearing in high-speed operation. Meanwhile, the feature that the inner wave foil 1021 made of super-elastic material does not fail after entering the super-elastic stage also increases the reliability and service life of the bearing.

[0074] Further, the inner wave-shaped protrusions 10211 on the inner layer wave foil 1021 have shapes that vary along the circumferential direction of the bearing; correspondingly, the outer wave-shaped protrusions 10221 on the outer layer wave foil 1022 also have shapes that vary along the circumferential direction of the bearing.

[0075] Preferably, in the circumferential direction of the bearing, the inner wave-shaped protrusions 10211 and the outer wave-shaped protrusions 10221 are semi-elliptical.

[0076] Further, the first foil group 1a is located at the upper part of the bearing seat 2, at this time, the inner wave-shaped protrusions 10211 and the outer wave-shaped protrusions 10221 located in the middle are located directly above the central axis of the bearing seat 2, and the remaining inner wave-shaped protrusions 10211 and outer wave-shaped protrusions 10221 are symmetrically arranged along the circumferential direction of the bearing with the inner wave-shaped protrusions 10211 and the outer wave-shaped protrusions 10221 located in the middle as the center.

[0077] Correspondingly, the second foil group 1b is located at the lower part of the bearing seat 2, at this time, the inner wave-shaped protrusions 10211 and the outer wave-shaped protrusions 10221 located in the middle are located directly below the central axis of the bearing seat 2, and the remaining inner wave-shaped protrusions 10211 and outer wave-shaped protrusions 10221 are symmetrically arranged along the circumferential direction of the bearing with the inner wave-shaped protrusions 10211 and the outer wave-shaped protrusions 10221 located in the middle as the center.

[0078] Further, as shown in Figure 5 The distance between the two ends of the inner wave-shaped protrusions 10211 and the outer wave-shaped protrusions 10221 is recorded as the width W of the wave-shaped protrusions, the distance between the two ends of the inner wave-shaped protrusions 10211 and the outer wave-shaped protrusions 10221 and the wave crest is recorded as the height H of the wave-shaped protrusions, at the same time, the wave-shaped protrusions located directly above or below the central axis of the bearing seat 2 in the inner layer wave foil 1021 and the outer layer wave foil 1022 are called central wave-shaped protrusions, and the width of the central wave-shaped protrusions is recorded as W1, and the widths of the wave-shaped protrusions on both sides of the central wave-shaped protrusions are recorded as W2, W3, W4, …, Wn in turn, and correspondingly, the heights of the wave-shaped protrusions on both sides of the central wave-shaped protrusions are recorded as H2, H3, H4, …, Hn in turn, then the values of H1 / W1, H2 / W2, H3 / W3, H4 / W4, …, Hn / Wn gradually decrease.

[0079] Further, the heights H of the inner wave-shaped protrusions 10211 and the outer wave-shaped protrusions 10221 at different radial directions of the bearing are equal.

[0080] According to Figure 5It can be seen that when the inner wave-shaped protrusion 10211 and the outer wave-shaped protrusion 10221 are semi-elliptical, half of the width W of the wave-shaped protrusion is the short radius of the semi-ellipse, and the height H of the wave-shaped protrusion is the long radius of the semi-ellipse. At this time, from the center of the inner wave foil 1021 and the outer wave foil 1022 to both sides, the ratio of the long radius to the short radius of the inner wave-shaped protrusion 10211 and the outer wave-shaped protrusion 10221, i.e. H1 / (0.5*W1), H2 / (0.5*W2), H3 / (0.5*W3), H4 / (0.5*W4), …, Hn / (0.5*Wn) gradually decreases. In this case, from the center of the inner wave foil 1021 and the outer wave foil 1022 to both sides, the ratio of the long radius to the short radius of the inner wave-shaped protrusion 10211 and the outer wave-shaped protrusion 10221 gradually decreases, and the shape gradually approaches a semicircle, and the radial support stiffness gradually decreases. The radial support stiffness of the wave foil 102 changes along the circumference of the bearing, which is consistent with the distribution of the gas film pressure along the circumference of the bearing, so the carrying capacity of the bearing can be effectively improved. Figure 5 It can be seen that the ratio of the long radius to the short radius of the inner wave-shaped protrusion 10211 and the outer wave-shaped protrusion 10221 located directly below the center axis of the bearing seat 2 is the largest, and the shape is the most slender, which can provide higher radial support stiffness; then from the center of the inner wave foil 1021 and the outer wave foil 1022 to both sides, the ratio of the long radius to the short radius of the inner wave-shaped protrusion 10211 and the outer wave-shaped protrusion 10221 gradually decreases, and the shape gradually approaches a semicircle, and the radial support stiffness gradually decreases. The radial support stiffness of the wave foil 102 changes along the circumference of the bearing, which is consistent with the distribution of the gas film pressure along the circumference of the bearing, so the carrying capacity of the bearing can be effectively improved.

[0081] Further, the dynamic pressure air radial bearing further comprises:

[0082] A positioning plate 4 is formed by extending radially outward from the end edge of the bearing seat 2, and the positioning plate 4 is in the form of an annular structure surrounding the outer wall of the bearing seat 2;

[0083] A plurality of locking screws 3 are used to fix the positioning plate 4 to the bearing seat 2.

[0084] As Figure 2 A front view of a three-dimensional assembly model of the dynamic pressure air radial bearing is shown, which shows the structure of the positioning plate 4, the plurality of shaft end locking screws 3 and the bearing seat 2 of the two shaft ends. It should be noted that in Figure 2 In order to facilitate display, the positioning plate 4 in the front view is transparent.

[0085] Further, a connecting hook 1031 is arranged at the fixed end 103 of the foil group 1, and a connecting groove 201 is arranged on the bearing seat 2, the connecting hook 1031 is inserted and hooked on the connecting groove 201, and the installation of the fixed end 103 of the foil group 1 is realized.

[0086] Preferably, the connecting hook 1031 is in a circular arc structure, and correspondingly, the connecting groove 201 is also a circular arc groove, the circular arc connecting hook 1031 is inserted and hooked on the connecting groove 201, so as to realize the connection between the fixed end 103 and the bearing, and further realize the detachable installation of the foil group 1.

[0087] In the present application, the connecting hook 1031 of the two foil groups 1 fixed ends 103 does not need to be welded, has the advantage of convenient disassembly, and the assembly and use process are more convenient, and the replacement of the foil group 1 also becomes very convenient.

[0088] It should be noted that, considering the attached Figure 3 In the present application, the shape of the foil group 1 in the P1 and P2 regions is consistent, and in Figure 4 In the present application, only the shape of the foil group 1 in the P1 region is enlarged and observed.

[0089] In addition, in the dynamic pressure air radial bearing described in the present application, although the two foil groups 1 along the circumference are completely the same in structure and material, the lower foil group 1 bears the main load and start-stop wear, so that after a certain number of start-stop times, the lower foil group 1 that fails due to start-stop wear and the like can be replaced alone, without the need to replace the upper foil group 1 that bears a lower load, thereby improving the utilization efficiency of the bearing and the foil.

[0090] In addition, the present application also discloses a preparation method of the above-mentioned dynamic pressure air radial bearing, and the implementation steps are as follows:

[0091] S1, designing and processing a mold of the outer layer wave foil 1022 and the inner layer wave foil 1021;

[0092] S2, processing the corrugated structures in the outer layer wave foil 1022 and the inner layer wave foil 1021 by stamping sheet metal based on two stamping molds, that is, the inner wave-shaped protrusions 10211 and the inner arc segments 10212 alternately arranged in the circumferential direction in the inner layer wave foil 1021, and the outer wave-shaped protrusions 10221 and the outer arc segments 10222 alternately arranged in the circumferential direction in the outer layer wave foil 1022;

[0093] S3, bending the flat foil 101, the inner layer wave foil 1021 and the outer layer wave foil 1022 into circular arcs as a whole respectively, and bending one end of them into a set hook, to obtain the connecting hook 1031 of the foil group 1 fixed end 103, and thus the processing of the foil group 1 is completed;

[0094] S4, processing the hook-shaped connecting groove 201 on the bearing seat 2;

[0095] S5, the outer layer wave foil 1022, the inner layer wave foil 1021, flat foil 101 is arranged in the order of radially from outside to inside to form a foil group, and two foil groups 1 are connected to the bearing seat 2 through the connecting hook 1031, then the positioning plate 4 is connected to the bearing seat 2 through the locking screw 3, and the assembly of the whole bearing is completed.

[0096] In summary: the dynamic pressure air radial bearing has the following advantages:

[0097] First, the inner layer wave foil prepared from the super-elastic material in the dynamic pressure air radial bearing can effectively suppress the vibration of the rotor and improve the stability of the bearing under high-speed working conditions by consuming the vibration energy of the rotor through the high damping characteristics of the super-elastic stage.

[0098] Second, the dynamic pressure air radial bearing fully considers the actual load environment of the bearing, and changes the shape of the wave foil in the circumferential direction to realize the radial supporting stiffness in the circumferential direction, wherein the wave foil structure in the high gas film pressure (high load) area has higher radial supporting stiffness, which can effectively improve the carrying capacity; at the same time, the radial supporting stiffness of the bearing wave foil designed by the application is consistent with the distribution law of the gas film pressure along the circumferential direction of the bearing, which can also effectively improve the carrying capacity of the bearing.

[0099] Third, the dynamic pressure air radial bearing has two layers of wave foil structure distributed in the radial direction, which are the inner layer wave foil and the outer layer wave foil, and the two layers of wave foils deform together to provide support under high load working conditions, which can effectively improve the carrying capacity; under light load working conditions, only the inner layer wave foil with super-elasticity deforms and provides carrying capacity, so that the carrying capacity of the bearing under heavy load working conditions is effectively improved.

[0100] Fourth, the dynamic pressure air radial bearing adopts the method of dividing the foil into two groups in the circumferential direction, which breaks the continuity of the supporting gas film in the circumferential direction, weakens the radial cross support stiffness of the bearing, and further suppresses the subsynchronous amplitude of the rotor and improves the running stability of the bearing, and improves the anti-disturbance ability of the bearing.

[0101] In summary, the dynamic pressure air radial bearing with double-layer circumferential variable stiffness wave foil has the advantages of high carrying capacity and strong stability during high-speed operation.

[0102] The embodiments of the present application are described above with reference to the drawings, and the embodiments and features in the embodiments of the present application can be combined with each other without conflict, and the present application is not limited to the above-described specific embodiments, and the above-described specific embodiments are only illustrative but not restrictive, and a person of ordinary skill in the art can make many forms under the inspiration of the present application without departing from the purpose of the present application and the scope protected by the claims, and all belong to the protection of the present application.

Claims

1. A dynamic pressure air radial bearing with double-layer circumferential variable stiffness wave foils, comprising: a bearing housing (2) having a shell inner wall for enclosing a circular hollow inner cavity accommodating a rotor; a plurality of foil groups (1) arranged in the circular hollow inner cavity, one end of the foil group (1) being a fixed end (103) fixed to the bearing housing (2), the other end being a free end (104), the plurality of foil groups (1) being arranged in the circular hollow inner cavity in a whole annular shape clockwise or counterclockwise with the fixed end (103) as the head and the free end (104) as the tail; the foil group (1) comprising: a flat foil (101) in a whole circular arc shape, the flat foil (101) being coaxially arranged with the bearing housing (2); a wave foil (102) in a whole circular arc shape, the wave foil (102) being arranged between the inner wall of the bearing housing (2) and the outer wall of the flat foil (101); characterized in that the wave foil (102) comprises: an inner layer wave foil (1021) arranged on one side close to the flat foil (101) and an outer layer wave foil (1022) arranged on one side close to the inner wall of the bearing housing (2), the inner layer wave foil (1021) being made of super-elastic material and the outer layer wave foil (1022) being made of elastic material; the inner layer wave foil (1021) being provided with inner wave-shaped protrusions (10211) and inner arc segments (10212), the inner wave-shaped protrusions (10211) and the inner arc segments (10212) being alternately arranged along the circumferential direction of the bearing housing (2); correspondingly, the outer layer wave foil (1022) is provided with outer wave-shaped protrusions (10221) and outer arc segments (10222), the outer wave-shaped protrusions (10221) and the outer arc segments (10222) being alternately arranged along the circumferential direction of the bearing housing (2); the inner layer wave foil (1021) and the outer layer wave foil (1022) are superimposed, the inner wave-shaped protrusions (10211) and the outer wave-shaped protrusions (10221) are correspondingly arranged, and a preset gap (1023) is formed between the inner wave-shaped protrusions (10211) and the outer wave-shaped protrusions (10221); the inner arc segments (10212) and the outer arc segments (10222) are correspondingly arranged, and the outer wall of the inner arc segment (10212) and the inner wall of the outer arc segment (10222) are connected.

2. The dynamic pressure air radial bearing of claim 1, wherein, the inner wave-shaped protrusions (10211) and the outer wave-shaped protrusions (10221) are arranged in parallel, and the width of the preset gap (1023) is a constant value.

3. The dynamic pressure air radial bearing of claim 1 wherein, the wave crest of the inner wave-shaped protrusion (10211) is in contact with the outer wall of the flat foil (101); and the outer wall of the outer arc segment (10222) is connected with the inner wall of the bearing housing (2).

4. The dynamic pressure air radial bearing of claim 2, wherein, The inner wave-shaped protrusions (10211) on the inner layer wave foil (1021) have shapes that vary along the circumferential direction of the bearing; correspondingly, the outer wave-shaped protrusions (10221) on the outer layer wave foil (1022) also have shapes that vary along the circumferential direction of the bearing.

5. The dynamic pressure air radial bearing of claim 4, wherein, In the circumferential direction of the bearing, the inner wave-shaped protrusions (10211) and the outer wave-shaped protrusions (10221) are semi-elliptical.

6. The dynamic pressure air radial bearing of claim 5, wherein, The dynamic pressure air radial bearing comprises two foil groups (1), namely a first foil group (1a) and a second foil group (1b), the first foil group (1a) is located at the upper part of the bearing seat (2), the inner wave-shaped protrusions (10211) and the outer wave-shaped protrusions (10221) located in the middle are located directly above the central axis of the bearing seat (2), and the remaining inner wave-shaped protrusions (10211) and outer wave-shaped protrusions (10221) are symmetrically arranged along the circumferential direction of the bearing with the inner wave-shaped protrusions (10211) and the outer wave-shaped protrusions (10221) located in the middle as the center; Correspondingly, the second foil group (1b) is located at the lower part of the bearing seat (2), the inner wave-shaped protrusions (10211) and the outer wave-shaped protrusions (10221) located in the middle are located directly below the central axis of the bearing seat (2), and the remaining inner wave-shaped protrusions (10211) and outer wave-shaped protrusions (10221) are symmetrically arranged along the circumferential direction of the bearing with the inner wave-shaped protrusions (10211) and the outer wave-shaped protrusions (10221) located in the middle as the center.

7. The dynamic pressure air radial bearing of claim 6, wherein, From the center of the inner layer wave foil (1021) and the outer layer wave foil (1022) to both sides, the ratio of the long radius to the short radius of the inner wave-shaped protrusions (10211) and the outer wave-shaped protrusions (10221) gradually decreases.

8. The dynamic pressure air radial bearing of claim 1 wherein, The dynamic pressure air radial bearing further comprises: A positioning plate (4) is formed by extending radially outward from the end edge of the bearing seat (2), and the positioning plate (4) has an annular structure arranged around the outer wall of the bearing seat (2); A plurality of locking screws (3) are used to fix the positioning plate (4) on the bearing seat (2); A connecting hook (1031) is arranged at the fixed end (103) of the foil group (1), and a connecting groove (201) is arranged on the bearing seat (2), the connecting hook (1031) is inserted and hooked on the connecting groove (201).

9. The dynamic pressure air radial bearing of any of claims 1-8, wherein, The preparation process of the dynamic pressure air radial bearing comprises the following steps: S1, designing and processing the molds of the outer layer wave foil and the inner layer wave foil; S2, processing the corrugated structures in the outer layer wave foil and the inner layer wave foil by stamping sheet metal based on the two molds; S3, bending the flat foil, the inner layer wave foil and the outer layer wave foil into circular arcs as a whole, and bending one end of each into a hook shape to obtain a connecting hook; S4, processing a connecting groove on the bearing seat; S5, the outer layer wave foil, inner layer wave foil, flat foil along the radial from outside to inside the order of foil group, and through the connection hook will be two foil group connected to the bearing seat, after the positioning plate through the locking screw connected to the bearing seat, complete the assembly of the entire bearing.

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