Air bearing and detection method

Abstract

The application relates to the technical field of bearings, in particular to an air floating bearing and a detection method. The air floating bearing comprises a seat body, an air inlet of the seat body, a rotor rotatably arranged in the seat body, and a shaft sleeve arranged between the rotor and the seat body to form a gap between the shaft sleeve and the rotor. The air inlet is connected to the shaft sleeve, and the shaft sleeve is provided with a through hole penetrating through the side wall of the shaft sleeve, so that air flows into the gap through the through hole from the air inlet to form an air film between the shaft sleeve and the rotor. The shaft sleeve is at least partially deformable to dynamically adapt the air film state between the rotor and the shaft sleeve. The machining quality of the air floating bearing is improved by dynamically adjusting the air film gap.

Description

Technical Field

[0001] This application relates to the field of bearing technology, and in particular to an air bearing and a testing method. Background Technology

[0002] Air bearings, as a type of non-contact bearing that uses gas as a lubricating medium, have become a core component in high-end equipment fields such as precision machine tools, high-speed motors, aerospace equipment, and precision instruments due to their significant advantages of no solid contact friction, high operating accuracy, low wear, and low noise. They ensure the high-speed, stable, and precise operation of such equipment. The working principle of air bearings is to form a stable air film between the bearing and the rotor. The non-contact relative motion between the rotor and bearing is achieved by relying on the load-bearing capacity of the air film, effectively avoiding the friction loss and accuracy degradation problems of traditional contact bearings. They are particularly suitable for high-speed, variable-load, and high-precision operating conditions. As high-end equipment develops towards higher speeds, greater precision, and greater integration, the application scenarios of air bearings are constantly expanding, and the requirements for their operational stability and adaptability are also increasing.

[0003] In existing technologies, the uniformity and stability of the air film determine the performance of air bearings. However, the eccentricity problem that occurs during the processing and assembly of air bearings can easily lead to machining eccentricity between the rotor and the bearing surface in actual production. Positioning deviations during assembly will further exacerbate the eccentricity. This results in an uneven distribution of the air film gap between the rotor and the bearing surface. Under high-speed operating conditions, the air film gap in the eccentric area is compressed, and the pressure rises sharply. The air film gap in the non-eccentric area is too large and the pressure is insufficient, which in turn causes air film oscillation and rotor whirl. In severe cases, it can lead to air film rupture, causing slight contact wear between the bearing surface and the rotor, and shortening the bearing's service life. Furthermore, the air film pressure fluctuations caused by eccentricity during high-speed operation lead to unstable air film in the processing equipment and a decline in workpiece processing quality.

[0004] Therefore, the technical problem with the existing technology is that the processing quality of air bearings is relatively low. Summary of the Invention

[0005] This application provides an air bearing and a testing method, which achieves the technical effect of improving the processing quality of the air bearing by dynamically adjusting the air film gap.

[0006] On the one hand, the air bearing provided in this application adopts the following technical solution: An air bearing, comprising: The seat body has an air inlet; A rotor, rotatably disposed within the base, such that the rotor can rotate about its axial direction relative to the base; and A bushing is disposed between the rotor and the base to create a gap between the bushing and the rotor; an air inlet leads to the bushing, and the bushing has a through hole penetrating through the side wall of the bushing, so that airflow enters from the air inlet and then enters the gap through the through hole to form an air film between the bushing and the rotor; wherein, the bushing is at least partially deformable to dynamically adapt to the air film state between the rotor and the bushing.

[0007] Preferably, the bushing comprises, radially from the inside to the outside: The first layer is disposed facing the rotor and is rigid. The second layer is connected to the second layer and is disposed facing the base. The second layer is deformable.

[0008] Preferably, the first layer is a composite ceramic material of zirconium oxide and alumina, wherein the mass fraction of zirconium oxide is 70%-80% and the mass fraction of alumina is 20%-30%.

[0009] As a preferred option, the second layer is made of beryllium bronze.

[0010] Preferably, the second layer has a porous structure arranged in a gradient, and the porosity of the second layer increases from the side closer to the first layer to the side closer to the base.

[0011] Preferably, the bushing further includes a third layer disposed between the first layer and the second layer, the third layer being used for bonding and buffering the first layer and the second layer.

[0012] Preferably, the seat body has an air groove on the side opposite to the bushing, the air groove is connected to the air inlet, and the air groove is positioned facing the bushing so that the airflow in the air groove can supply gas between the rotor and the bushing through the through hole to form an air film.

[0013] Preferably, the system also includes a sensing structure, which includes a fiber Bragg grating sensor embedded inside the second layer. The fiber Bragg grating sensor is used to collect deformation signals of the second layer.

[0014] On the other hand, the detection method for air bearings provided in this application adopts the following technical solution: A method for testing air bearings, comprising: Obtain the fiber optic parameters collected by the fiber Bragg grating sensor; The amount of change in the second layer is determined based on the fiber parameters; Based on the change in the second layer, the air film gap between the rotor and the bushing is determined.

[0015] As preferred, including: The fiber parameters include the deployment angle of the fiber Bragg grating sensor. and corresponding angles Fiber wavelength offset at location ; Based on the fiber wavelength offset Determine the microstrain of the second layer ; Microstrain based on the second layer Determine the radial deformation of the second layer ; Based on the radial deformation of the second layer Determine the air film gap .

[0016] Preferably, the microstrain of the second layer :

[0017] This represents the measured wavelength offset of the optical fiber. The fiber strain sensitivity coefficient; Radial deformation of the second layer :

[0018] This is the initial thickness of the second layer; The elastic modulus of the second non-porous layer; For angle The effective elastic modulus of the second layer; The second layer's effective elastic modulus :

[0019] This is the correction factor for the effect of porosity; For angle Local porosity of the inner layer; The air film gap :

[0020] This represents the initial gap of the air film. This is the Poisson's ratio correction factor; The Poisson's ratio of the second layer material.

[0021] In summary, this application includes at least one of the following beneficial technical effects: The bushing provided in this application between the base and the rotor can deform to dynamically adjust the air film clearance, adapt to air film pressure fluctuations under high-speed variable load conditions, suppress uneven air film clearance and air film oscillation, and improve bearing operation stability. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the air bearing described in this application; Figure 2 This is a schematic diagram of the through hole of the air bearing described in this application; Figure 3 This is a schematic diagram of the first embodiment of the bushing of the air bearing described in this application; Figure 4 This is a schematic diagram of a second embodiment of the bushing of the air bearing described in this application; Figure 5 This is a schematic diagram of the air groove of the air bearing described in this application; Figure 6 It is the fiber optic grating sensor for the air bearing described in this application; Figure 7 This is a schematic diagram of the first process of the air bearing testing method described in this application; Figure 8 This is a schematic diagram of the second process of the air bearing testing method described in this application.

[0023] Explanation of reference numerals in the attached drawings: 100, base; 110, air inlet; 120, air groove; 200, rotor; 300, bushing; 310, through hole; 321, first layer; 322, second layer; 323, third layer; 400, gap; 500, fiber optic grating sensor. Detailed Implementation

[0024] The serial numbers assigned to components in this document, such as "first" and "second," are used solely to distinguish the described objects and have no sequential or technical meaning. The terms "connection" and "linkage" used in this application, unless otherwise specified, include both direct and indirect connections (linkages). It should be understood that the terms "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are used solely for the convenience of describing this application and simplifying the description. They 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, and therefore should not be construed as a limitation of this application.

[0025] In this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0026] To better understand the above technical solutions, a detailed description of the technical solutions will be provided below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative of this application and are not intended to limit the scope of this application.

[0027] The working principle of air bearings is to form a stable air film between the bearing and the rotor 200. The non-contact relative motion between the rotor 200 and the bearing is achieved by relying on the load-bearing capacity of the air film. This effectively avoids the friction loss and precision decay problems of traditional contact bearings. It is especially suitable for high-speed variable load and high-precision operation conditions. As high-end equipment develops towards high speed, precision and integration, the application scenarios of air bearings are constantly expanding, and the requirements for their operational stability and adaptability are also increasing.

[0028] Traditional bearing surfaces cannot adapt to the fluctuations in air film pressure under high-speed variable loads, which can easily lead to uneven air film gaps (400°) and even air film rupture. Furthermore, the compressibility of air further reduces bearing rigidity and exacerbates air film instability under load changes. In addition, the bearing surface has insufficient wear resistance, and if the air film is unstable, slight contact can easily cause surface scratches. Therefore, the problem of air film instability during the operation of air bearings urgently needs to be solved.

[0029] This application proposes an air bearing, such as Figure 1 , 2As shown, the air bearing includes a housing 100, a rotor 200, and a bushing 300. The bushing 300 is disposed between the rotor 200 and the housing 100 and has a deformable portion, which can dynamically adapt to the air film state to improve the stability of the air film. Specifically, the air bearing includes a housing 100, a rotor 200, and a bushing 300. The housing 100 is the fixed support structure of the bearing and has an air inlet 110 for connecting to an external high-pressure air source. The rotor 200 is rotatably disposed inside the housing 100 and can rotate relative to the housing 100 about the axis of the rotor 200. The bushing 300 is disposed between the rotor 200 and the housing 100, such that there is a gap 400 between the bushing 300 and the rotor 200. The gap 400 is the space for the formation of an air film. The air inlet 110 leads to the bushing 300, and the bushing 300 has a through hole 310 that penetrates the side wall of the bushing 300. This allows the airflow to enter through the air inlet 110 and then through the through hole 310 into the gap 400 between the bushing 300 and the rotor 200, thereby forming a load-bearing air film between the bushing 300 and the rotor 200, achieving non-contact support between the rotor 200 and the bushing 300. The bushing 300 is at least partially deformable and can undergo elastic deformation according to changes in the air film state to dynamically adapt to the air film state between the rotor 200 and the bushing 300, suppressing problems such as uneven air film gap 400 and air film pressure fluctuations, and improving the stability of bearing operation.

[0030] In other words, such as Figure 1 , 2 As shown, the inner wall of the base 100 fits against the outer wall of the bushing 300, providing radial support for the bushing 300; the rotor 200 is a cylindrical structure, coaxially arranged with the base 100, and an initial gap 400 is formed between the outer circular surface of the rotor 200 and the inner circular surface of the bushing 300, which is the initial space of the air film; the air inlet 110 is provided on the side wall of the base 100 and communicates with the air supply channel inside the base 100. External high-pressure gas enters the interior of the base 100 through the air inlet 110, and then enters the bushing 300 through the through hole 310 on the bushing 300. The gap 400 between the rotors 200 forms a high-pressure air film, which suspends and supports the rotors 200 by the pressure of the air film, enabling frictionless rotation of the rotors 200. The through holes 310 on the bushing 300 are evenly distributed along the circumference and axial direction of the bushing 300, ensuring that the airflow can enter the gap 400 evenly and form a uniformly distributed air film. The deformable part of the bushing 300 is the flexible inner layer of the bushing 300, which can undergo elastic deformation when the air film pressure changes, dynamically adjusting the gap 400 between the bushing 300 and the rotor 200, and realizing dynamic adaptation of the air film state.

[0031] Furthermore, such as Figure 3As shown, the bushing 300 includes a first layer 321 and a second layer 322 radially from the inside out. The first layer 321 is a rigid surface layer facing the rotor 200. The first layer 321 is opposite to the outer circular surface of the rotor 200 and directly contacts the air film, providing a smooth and wear-resistant contact surface for the air film. The second layer 322 is an inner layer connected to the outside of the first layer 321. The second layer 322 is flexible and can undergo elastic deformation, providing the bushing 300 with deformability and realizing dynamic adaptation of the air film state. The first layer 321 and the second layer 322 are tightly fitted radially to form an integrated bushing 300 structure. On the one hand, this improves the rigidity and wear resistance of the contact surface between the bushing 300 and the rotor 200. On the other hand, the deformation capability of the flexible inner layer enables dynamic adjustment of the air film state.

[0032] The first layer 321 is the inner surface layer of the bushing 300, which is in direct contact with the air film. It needs to have high hardness, high wear resistance and low surface roughness to reduce air film shear resistance, avoid scratches caused by the contact between the rotor 200 and the bushing 300 during start-up and shutdown, and extend the service life of the bearing. The second layer 322 is the outer layer of the bushing 300, which is in close contact with the inner wall of the housing 100. It needs to have good elastic deformation capability, so that it can elastically compress or rebound when the air film pressure changes, dynamically adjust the gap 400 between the bushing 300 and the rotor 200, adapt to air film pressure fluctuations, and suppress rotor 200 eccentricity and whirl.

[0033] In one embodiment, the first layer 321 is a composite ceramic material of zirconium oxide and alumina, wherein the mass fraction of zirconium oxide is 70%-80% and the mass fraction of alumina is 20%-30%. The composite ceramic material is formed through a hot-pressing sintering process, with the sintering temperature controlled at 1300-1500℃ and the axial pressure controlled at 20-100MPa, ensuring that the material density reaches over 99%. It has extremely high hardness and wear resistance, with a hardness of HRC85-90, which can effectively resist the wear caused by slight contact between the rotor 200 and the bushing 300 during start-up and shutdown, and avoid gas film leakage caused by surface scratches. At the same time, the material is precision polished, with a surface roughness Ra≤0.01μm, which can reduce the shear resistance of the gas film, adapt to the high-speed rotation requirements of the rotor 200, reduce gas film shear heating, and improve gas film stability. The addition of zirconium oxide can improve the toughness of the ceramic material and reduce crack formation, while alumina can improve the hardness and wear resistance of the material. The combination of the two achieves a balance of high hardness, high toughness and high wear resistance on the surface, which is suitable for the high-speed and precision operation of air bearings.

[0034] Preferably, the mass fraction of zirconium oxide in the first layer 321 can be 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79% or 80%, and the corresponding mass fraction of alumina can be 30%, 29%, 28%, 27%, 26%, 25%, 24%, 23%, 22%, 21% or 20%.

[0035] The second layer, 322, is made of beryllium bronze, which possesses excellent elastic deformation capabilities, along with good toughness and fatigue resistance. It can undergo slight elastic deformation under changes in film pressure and quickly return to its original shape without plastic deformation, ensuring long-term operational stability. The elastic deformation characteristics of beryllium bronze effectively adapt to dynamic changes in film pressure. When the film pressure increases, the second layer 322 undergoes elastic compression, causing the first layer 321 to move slightly outward, widening the film gap 400. When the film pressure decreases, the second layer 322 elastically rebounds, causing the first layer 321 to move slightly inward, narrowing the film gap 400, achieving dynamic homogenization of the film gap 400, suppressing film pressure fluctuations, and improving bearing operational stability. Simultaneously, beryllium bronze has good thermal conductivity, enabling rapid dissipation of heat generated by film shear, reducing bearing operating temperature and improving structural stability.

[0036] Furthermore, the second layer 322 has a porous structure arranged in a gradient, and the porosity of the second layer 322 increases from the side closer to the first layer 321 to the side closer to the base 100.

[0037] The second layer 322 has a gradient porous structure, with the porosity increasing from the side near the first layer 321 to the side near the base 100. In a preferred embodiment, the porosity on the side near the first layer 321 is 20%-25%, and the porosity on the side near the base 100 is 30%-35%, with a pore diameter of 5-20 μm. This gradient porous structure combines gas storage and flexible deformation capabilities: on the one hand, the pores can serve as auxiliary gas storage spaces for the gas film. When the gas film pressure increases, gas can enter and be stored in the pores; when the gas film pressure decreases, the gas in the pores can be released, achieving buffering and homogenization of the gas film pressure, weakening the effects of airflow pulsation and eddies, and reducing the risk of gas film oscillation, especially... The effect is significant under non-steady-state conditions such as start-stop, rapid acceleration, and sudden load changes. On the other hand, the gradient porosity causes the effective elastic modulus of the second layer 322 to change in a radial gradient. The side closer to the first layer 321 has low porosity, dense material, and high effective elastic modulus, which can provide stable support for the first layer 321. The side closer to the seat 100 has high porosity, loose material, low effective elastic modulus, and stronger deformation capacity. It can undergo differentiated deformation according to the change of air film pressure, and achieve precise adaptation of the air film gap 400. At the same time, the gradient porous structure does not affect the overall elastic deformation capacity of the second layer 322, and the deformation characteristics of the second layer 322 can be adjusted by adjusting the porosity distribution to adapt to different working conditions.

[0038] Based on the first layer 321 and the second layer 322, such as Figure 4 As shown, the bushing 300 also includes a third layer 323 disposed between the first layer 321 and the second layer 322. The third layer 323 is used to bond and buffer the first layer 321 and the second layer 322. The third layer 323 is a nickel-based alloy containing titanium and chromium, with titanium comprising 5%-8% by mass and chromium comprising 3%-5% by mass. This material has a bonding strength ≥350MPa, enabling a strong bond between the first layer 321 (ceramic) and the second layer 322 (beryllium bronze), preventing delamination. Simultaneously, the third layer 323 possesses excellent buffering properties, mitigating the impact of gas film pressure fluctuations on the first layer 321 ceramic, reducing surface cracking, improving structural stability, and adapting to pressure fluctuation scenarios under high-speed variable loads. In one embodiment, the thickness of the first layer 321 is 1.5-2.5mm, the second layer 322 is 6-8.5mm, and the third layer 323 is 0.5-1mm. This ensures sufficient bonding strength without affecting the overall deformation characteristics of the bushing 300, effectively transmitting gas film pressure and transferring the pressure received by the first layer 321 completely to the second layer 322, achieving effective pressure transmission and precise deformation response.

[0039] like Figure 5As shown, in order to improve the uniformity of air intake inside the air bearing, the seat 100 is provided with an air groove 120 on the side opposite to the bushing 300. The air groove 120 is connected to the air inlet 110. The air groove 120 is positioned facing the bushing 300 so that the airflow in the air groove 120 can supply gas between the rotor 200 and the bushing 300 through the through hole 310 to form an air film.

[0040] A groove 120 is provided on the side of the base 100 opposite to the bushing 300. The groove 120 is connected to the air inlet 110. The groove 120 is set facing the bushing 300 and is spirally arranged upward or downward with the center of the base 100 or the center of the rotor 200 as the center. In this way, when the air inlet 110 is connected to the groove 120, the airflow can flow along the groove 120 to the entire surface of the bushing 300. On the surface of the bushing 300, it enters between the bushing 300 and the rotor 200 through the through hole 310 to form an air film. The air groove 120 is a groove structure formed on the inner wall of the base 100, which fits against the outer wall of the bushing 300. When the external high-pressure gas enters the base 100 from the air inlet 110, it first enters the air groove 120. Since the air groove 120 is spirally distributed, the airflow can be evenly distributed on the inner wall of the base 100 along the spiral air groove 120, and then evenly enters the gap 400 between the bushing 300 and the rotor 200 through the through hole 310 on the bushing 300, forming a uniformly distributed air film. This avoids the problems of uneven local airflow and air film pressure fluctuation caused by traditional single-point air supply. The design of the spiral air groove 120 extends the flow path of the airflow, so that the airflow is evenly distributed on the inner wall of the base 100, ensuring that each through hole 310 on the bushing 300 can obtain a stable and uniform airflow supply, improving the uniformity of air film distribution and enhancing the stability of bearing operation. Meanwhile, the spiral arrangement of the air groove 120 can also guide the airflow, reduce airflow eddies, lower the shear resistance of the air film, and improve the load-bearing capacity of the air film.

[0041] Furthermore, such as Figure 6 As shown, the air bearing also includes a sensing structure, which includes a fiber optic grating sensor 500. The fiber optic grating sensor 500 is embedded inside the second layer 322 and is used to collect the deformation signal of the second layer 322.

[0042] The sensing structure includes a fiber Bragg grating sensor 500, which is embedded inside the second layer 322 and does not directly contact the air film. It is used to collect deformation signals from the second layer 322. The fiber Bragg grating sensor 500 has a diameter ≤0.1mm, does not occupy additional space, and can be adapted to the gradient porous structure of the second layer 322, avoiding interference from the sensor to the air film flow field and electromagnetic field, ensuring that the high-speed, precision operation of the bearing is unaffected. The fiber Bragg grating sensors 500 are uniformly distributed along the circumference of the bearing, allowing for simultaneous acquisition of signals from different angles. The deformation signal of the second layer 322 at the location can achieve circumferential full coverage detection of the deformation of the second layer 322; at the same time, multiple sets of sensors can also be deployed along the axial direction to realize deformation detection at different positions of the bearing axial direction, and comprehensively monitor the deformation state of the bushing 300; when the second layer 322 undergoes elastic deformation, the fiber optic grating sensor 500 will deform synchronously with the second layer 322, causing the wavelength of the fiber optic grating to shift. By detecting the amount of wavelength shift, the deformation signal of the second layer 322 can be obtained, thereby indirectly characterizing the state change of the air film.

[0043] This application also provides a method for testing air bearings, such as... Figure 7 As shown, the above-mentioned air bearing is applicable to the detection of the air film state during the operation of the air bearing. The detection method for air bearings includes: S1: Obtain the fiber parameters collected by the fiber optic grating sensor 500; the fiber optic parameters are the signal parameters related to the deformation of the second layer 322 collected by the fiber optic grating sensor 500. The fiber optic parameters can be obtained by demodulating the signal of the fiber optic grating sensor 500 through a demodulation device.

[0044] S2: Determine the change in the second layer 322 based on the fiber parameters; calculate the micro-strain of the second layer 322 based on the wavelength offset in the fiber parameters and the strain sensitivity coefficient of the fiber grating; and calculate the radial deformation of the second layer 322, i.e., the elastic compression or springback of the second layer 322, based on the material and structural parameters of the second layer 322.

[0045] S3: Based on the change in the second layer 322, determine the air film gap 400 between the rotor 200 and the bushing 300; according to the radial deformation of the second layer 322, combined with the structural parameters of the bushing 300 and the Poisson's ratio correction coefficient, calculate the air film gap 400 between the rotor 200 and the bushing 300, and realize the quantitative detection of the air film gap 400.

[0046] In this way, deformation signals are collected by the embedded fiber optic grating sensor 500 to indirectly characterize the air film state without direct contact with the air film, thus avoiding interference of the detection structure on the air film flow field. At the same time, the quantitative calculation of the air film gap 400 can be realized, providing an accurate basis for adaptive compensation.

[0047] More specifically, this application proposes a method for quantitatively detecting the state of the air film using a fiber Bragg grating sensor 500, such as... Figure 8 As shown, it includes: Fiber optic parameters include the placement angle of the fiber Bragg grating sensor. and corresponding angles Fiber wavelength offset at location ; T1: Based on fiber wavelength offset Determine the microstrain of the second layer ; T2: Microstrain based on the second layer Determine the radial deformation of the second layer ; T3: Radial deformation based on the second layer Determine the air film gap .

[0048] In other words, fiber optic parameters include the placement angle of the fiber Bragg grating sensor. and corresponding angles Fiber wavelength offset at location ,in This refers to the sensor's placement position along the circumference of the bearing. The wavelength offset of the fiber grating at this location reflects the degree of deformation of the second layer at that location; step S2 includes: first, based on the fiber wavelength offset... Determine the microstrain of the second layer micro-strain The deformation rate of the second layer at this angular position is calculated using the relationship between the strain sensitivity coefficient of the fiber grating and the wavelength shift; secondly, based on the micro-strain of the second layer... Determine the radial deformation of the second layer radial deformation The radial elastic compression of the second layer at this angular position is calculated by combining the initial thickness of the second layer, the non-porous elastic modulus, and the effective elastic modulus; step S3 includes: based on the radial deformation of the second layer Determine the air film gap air film gap The actual gap between the rotor and the bushing at this angular position is calculated by combining the initial gap of the air film and the Poisson's ratio correction coefficient, thereby realizing the circumferential quantitative detection of the air film gap and obtaining the air film gap distribution at different angular positions.

[0049] Among them, the microstrain of the second layer :

[0050] in, The measured wavelength offset of the optical fiber reflects the degree of deformation of the fiber grating at that location. The fiber strain sensitivity coefficient is an inherent parameter of the fiber grating. It is calibrated through factory testing and reflects the linear correlation between wavelength offset and micro-strain. For angle The micro-strain of the second layer is used to characterize the deformation rate of the second layer at that location. The micro-strain of the second layer is calculated by measuring the optical fiber wavelength offset, and a direct correlation between the optical fiber detection parameters and the inner layer deformation is established for subsequent radial deformation calculation.

[0051] Radial deformation of the second layer :

[0052] in, The initial thickness of the second layer is the thickness of the second layer before the shaft assembly; The second layer is the non-porous elastic modulus, which is the elastic modulus of beryllium bronze in a non-porous and dense state, reflecting the elastic properties of the material itself. For angle The effective elastic modulus of the second layer reflects the influence of the gradient porous structure on the elastic modulus; For angle The radial deformation of the second layer is the radial elastic compression of the second layer at that location. The radial deformation of the second layer is obtained through micro-strain calculation. Combined with the structural parameters and effective elastic modulus of the second layer, the influence of the gradient porous structure on the deformation is reflected, and the quantitative calculation of the inner layer deformation is realized.

[0053] Second layer effective elastic modulus :

[0054] in, is the porosity influence correction coefficient, and is a constant obtained from experimental fitting, reflecting the degree of influence of porosity on elastic modulus; For angle The local porosity of the inner layer is the porosity of the second layer at that angle position, reflecting the distribution characteristics of the gradient porous structure; For angle The effective elastic modulus of the second layer decreases with increasing porosity, reflecting the gradient distribution characteristics of the elastic modulus of the gradient porous structure. The effective elastic modulus is obtained by calculating the local porosity. Based on the influence of the gradient porous structure on the elastic modulus, the accuracy of the radial deformation calculation is ensured, and the gradient porous structure of the second layer is adapted.

[0055] air film gap :

[0056] This represents the initial gap of the air film. This is the Poisson's ratio correction factor; The Poisson's ratio of the second layer material.

[0057] in, This represents the initial gap of the air film, and the initial gap between the rotor and the bushing after the bushing is assembled. This is the Poisson's ratio correction factor. The Poisson's ratio of the second layer reflects the lateral shrinkage characteristics of the material during deformation. Used to correct the effect of radial deformation on the air film gap; For angle The air film gap at that location is the actual gap between the rotor and the bushing at that position. The air film gap is obtained by calculating the radial deformation of the second layer, establishing the correlation between the inner layer deformation and the air film gap, and realizing the quantitative detection of the air film gap.

[0058] Based on the above, it is possible to calculate from fiber wavelength offset to air film gap, with any angle input. Fiber wavelength offset at location The second layer of microstrain at that location can then be calculated sequentially. Radial deformation Effective elastic modulus Finally, the air film gap is obtained. Based on the calculated air-film gap It can generate cloud maps of the implementation status of the air film, which is beneficial for the back-end to conduct more intuitive and accurate data analysis of the air bearing.

[0059] Although preferred embodiments of this application have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of this application.

[0060] Obviously, those skilled in the art can make various modifications and variations to this application without departing from the spirit and scope of this application. Therefore, if such modifications and variations fall within the scope of the claims of this application and their equivalents, this application also intends to include such modifications and variations.

Claims

1. An air bearing, characterized in that, include: The seat (100) has an air inlet (110); A rotor (200) rotatably disposed inside the base (100) such that the rotor (200) is rotatable about its axial direction relative to the base (100); and A bushing (300) is disposed between the rotor (200) and the base (100) to create a gap (400) between the bushing (300) and the rotor (200); an air inlet (110) leads to the bushing (300), and the bushing (300) has a through hole (310) extending through the side wall of the bushing (300) so that airflow enters from the air inlet (110) and then enters the gap (400) through the through hole (310) to form an air film between the bushing (300) and the rotor (200); wherein the bushing (300) is at least partially deformable to adapt to the air film state between the rotor (200) and the bushing (300).

2. The air bearing according to claim 1, characterized in that, The bushing (300) includes, radially from the inside to the outside: The first layer (321) is disposed facing the rotor (200) and is rigid; The second layer (322) is connected to the second layer (322), the second layer (322) is disposed facing the seat (100), and the second layer (322) is deformable.

3. The air bearing according to claim 2, characterized in that, The first layer (321) is a composite ceramic material of zirconium oxide and alumina, wherein the mass fraction of zirconium oxide is 70%-80% and the mass fraction of alumina is 20%-30%.

4. The air bearing according to claim 2, characterized in that, The second layer (322) is made of beryllium bronze.

5. An air bearing according to claim 2 or 4, characterized in that, The second layer (322) has a porous structure arranged in a gradient, and the porosity of the second layer (322) increases from the side near the first layer (321) to the side near the seat (100).

6. The air bearing according to claim 2, characterized in that, The bushing (300) further includes a third layer (323) disposed between the first layer (321) and the second layer (322), the third layer (323) being used for bonding and buffering the first layer (321) and the second layer (322).

7. The air bearing according to claim 1, characterized in that, The seat (100) has an air groove (120) on one side opposite to the bushing (300). The air groove (120) is connected to the air inlet (110). The air groove (120) is positioned facing the bushing (300) so that the airflow in the air groove (120) can supply gas between the rotor (200) and the bushing (300) through the through hole (310) to form an air film.

8. The air bearing according to claim 1, characterized in that, It also includes a sensing structure, which includes a fiber Bragg grating sensor (500) embedded inside the second layer (322). The fiber Bragg grating sensor (500) is used to collect deformation signals of the second layer (322).

9. A method for detecting an air bearing as described in claim 8, characterized in that, include: Acquire the fiber optic parameters collected by the fiber optic grating sensor (500); The amount of change in the second layer (322) is determined based on the optical fiber parameters; Based on the change in the second layer (322), the air film gap (400) between the rotor (200) and the bushing (300) is determined.

10. The air bearing testing method according to claim 9, characterized in that, include: The fiber parameters include the deployment angle of the fiber Bragg grating sensor. and corresponding angles Fiber wavelength offset at location ; Based on the fiber wavelength offset Determine the microstrain of the second layer ; Microstrain based on the second layer Determine the radial deformation of the second layer ; Based on the radial deformation of the second layer Determine the air film gap .

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