M-shaped bird leg bionic gas foil bearing

Abstract

The present application relates to air bearing technical field, specifically to a kind of M-shaped bird leg bionical gas foil bearing, including bearing sleeve, composite damping part, top foil;The composite damping part of the present application adopts piezoelectric actuator to imitate bird leg muscle tissue, when bird is impacted when landing, can be quickly contracted to present high stiffness to resist deformation by muscle;And piezoelectric ceramic in piezoelectric actuator is based on its millisecond level fast response, high stiffness and instantaneous output characteristics, cooperate with pressure sensor and external control module, can quickly perceive rotor impact vibration and produce instantaneous micro-displacement compensation according to control signal, change gas film pressure distribution by quickly adjusting bionical foil support form, by this dynamic, feedback type adjustment, effectively inhibit the instantaneous large vibration caused by impact, in turn effectively inhibit the generation of sub-synchronous vibration phenomenon, solve the problem of insufficient adaptability of traditional foil bearing when facing wide-range variable working condition operation.

Description

Technical Field

[0001] This invention relates to the field of air bearing technology, specifically to an M-shaped bird leg biomimetic gas foil bearing. Background Technology

[0002] Gas foil bearings, as a type of self-acting hydrodynamic lubrication support element, do not require an external oil supply system. They use air or a specific gas as the lubricating medium and have advantages such as low power consumption, resistance to extreme environments, and adaptability to ultra-high speeds. They are widely used in aero engines, micro gas turbines, high-speed compressors, and flywheel energy storage, and are key components driving the development of high-speed rotating machinery towards lightweight and maintenance-free operation. In marine and shipboard environments, these bearings show unique potential: they fundamentally avoid the problem of lubricating oil failure due to seawater contamination, and by using corrosion-resistant alloy materials to make the foils, they can significantly improve their tolerance in high humidity and high salt spray environments, meeting the stringent requirements of long-term marine equipment for maintenance-free operation throughout its entire life cycle.

[0003] However, in actual service, the dynamic performance of gas foil bearings is affected by the dual nonlinear coupling of the compressibility of the gas medium and the elastic deformation of the foil structure, resulting in strong nonlinear characteristics in the film stiffness and damping characteristics. Especially near the critical speed and under varying operating conditions, it is often difficult to balance the film load-bearing capacity and stability. More importantly, the foil structure needs to continuously withstand dynamic impact loads from the high-speed rotor system during long-term service. These impacts mainly originate from rotor imbalance excitation, transient disturbances during acceleration and deceleration, and the superposition of external environmental vibrations, which can easily induce film instability and produce typical subsynchronous vibration phenomena. Once such self-excited vibrations are formed and amplified, they will not only significantly deteriorate the operating stability of the rotor system and greatly compress the stable operating speed range of the bearing, affecting the overall operating accuracy and reliability, but in severe cases, they can also cause abnormal rubbing between the rotor and the top foil, leading to foil wear, plastic deformation of the top foil, or even structural failure. In extreme cases, it can cause rotor jamming or bearing burnout.

[0004] When gas foil bearings are applied to ship equipment, the above problems are further aggravated by complex fundamental excitations: ships will generate significant low-frequency swaying and wave impacts when sailing in severe sea conditions, while the power system will be subjected to strong transient impacts when starting, braking or encountering underwater asymmetric loads; the coupling effect of this "fundamental excitation" and "rotor impact" can easily cause the gas film thickness of traditional foil bearings designed for stable operating conditions to fluctuate drastically, leading to instantaneous rubbing or structural fatigue; while existing passive suppression methods (such as optimizing foil parameters, adding elastic damping layers, and low-friction coatings) are limited by the inherent characteristics of the structure and are only effective for specific frequencies or operating conditions, and are seriously inadequate in adaptability to wide-range variable operating conditions and complex marine excitation environments. Summary of the Invention

[0005] To address the aforementioned problems, this invention proposes the following technical solution: an M-shaped bird-leg biomimetic gas foil bearing, comprising a bearing sleeve, a composite damping section, and a top foil; the bearing sleeve is cylindrical, and the top foil is a cylinder with an axial opening, its main body being C-shaped; a connecting plate is fixedly installed inside the bearing sleeve, and one side of the opening of the top foil is detachably fixedly connected to the end of the connecting plate away from the bearing sleeve; the top foil is disposed inside the bearing sleeve, and a composite damping section is disposed between the top foil and the bearing sleeve; the composite damping section comprises several foil groups arranged in a ring, each foil group consisting of multiple biomimetic foils; each foil group corresponds to a pressure... An electric actuator, a piezoelectric actuator, is installed at one end of the foil assembly near the bearing sleeve; each foil assembly includes several biomimetic foils stacked together, which are fixedly connected together by connecting beams to form a foil assembly; the biomimetic foil has two legs and two tips, and the overall structure of the biomimetic foil is M-shaped, with a top block fixedly connected to the middle position on the upper side of the biomimetic foil; the end of the top block is arc-shaped, and in the composite vibration damping part, the end of the top block contacts and adheres to the outer wall of the top foil; when the top foil is subjected to radial pressure, the biomimetic foil undergoes elastic deformation, the ends of the two legs of the biomimetic foil move away from each other, and at the same time the two tips of the M-shape approach the top block.

[0006] Preferably, the plurality of foil groups rotate around the central axis of the bearing sleeve to form the main body of the composite vibration damping part, with gaps left between each pair of adjacent foil groups.

[0007] Preferably, a slot is provided on the inner side wall of the bearing sleeve, and the legs of the bionic foil in the foil group are inserted into the slot.

[0008] Preferably, the piezoelectric actuator is fixedly installed between the two legs of the corresponding foil group.

[0009] Preferably, the piezoelectric actuator includes an actuation bracket and a piezoelectric ceramic. The actuation bracket is a rhomboid frame, and the piezoelectric ceramic is fixedly installed on the inner side of the actuation bracket. The two ends of the piezoelectric ceramic are fixedly connected to two opposite vertices on the inner side of the actuation bracket, respectively. The other two vertices of the actuation bracket are respectively facing the foil group and the inner wall of the bearing sleeve, wherein the vertex closest to the inner wall of the bearing sleeve is fixedly connected to the inner wall of the bearing sleeve.

[0010] Preferably, the piezoelectric ceramic is also equipped with a pressure sensor, which is electrically connected to an external control module, and the piezoelectric ceramic is also electrically connected to an external control module.

[0011] Preferably, the entire inner gap of the bearing sleeve is filled with damping material.

[0012] The beneficial effects of this invention are as follows: First, this invention mimics the "M-shaped" skeletal structure of bird hind limbs in the design of the foil assembly structure in the composite vibration damping section. Under stable navigation or static load conditions of the ship, the biomimetic foils forming the foil assembly form a geometrically stable rigid whole, exhibiting high static stiffness characteristics. This effectively supports the self-weight load of the rotor and the ship's power system, resists the continuous change in gravity direction caused by the ship's swaying, and avoids structural buckling instability. When the ship encounters severe sea conditions and experiences low-frequency large-amplitude swaying or wave impact, the geometric nonlinear characteristics of the M-shaped bending structure allow the oblique support section of the biomimetic foil to transform the linear transmission of radial vibration load into a broken line transmission. This achieves multiple load dispersion and buffering at the connection nodes, thereby significantly reducing the transmission efficiency of low-frequency basic excitation to the air film and exhibiting low dynamic stiffness characteristics under minute vibrations. This structure fundamentally solves the problem of traditional foil bearings being unable to balance stiffness and damping in marine environments and having insufficient low-frequency vibration isolation capabilities, effectively suppressing severe fluctuations in air film thickness and rotor rubbing caused by the ship's swaying.

[0013] II. The composite vibration damping section of this invention adopts the adaptive contraction characteristics of piezoelectric actuators, mimicking the leg muscle tissue of birds. When a ship encounters transient strong impacts such as underwater asymmetric loads, wave impacts, or power system startup / braking, the piezoelectric ceramics in the piezoelectric actuator, with their millisecond-level fast response, high stiffness, and instantaneous output characteristics, in conjunction with pressure sensors and external control modules, quickly sense the impact vibration of the rotor and generate instantaneous micro-displacement compensation based on control signals. This compensation action can quickly adjust the support shape of the biomimetic foil and actively change the air film pressure distribution, thereby effectively suppressing the instantaneous large-amplitude vibration and subsynchronous vibration phenomena caused by the impact. This dynamic feedback adjustment mechanism enables the bearing to maintain stable operation under complex sea conditions and wide-range variable operating conditions, solving the core bottleneck of traditional passive foil bearings, which are limited by the inherent structural characteristics in terms of adjustment capability and have insufficient adaptability when facing multi-source excitation in the ocean. Attached Figure Description

[0014] Figure 1 This is an exploded view of the three-dimensional structure of the present invention.

[0015] Figure 2 This is a front view of the present invention.

[0016] Figure 3 This is a schematic diagram of the composite vibration damping section of the present invention after the piezoelectric actuator has been removed.

[0017] Figure 4 This is the state of the biomimetic foil of the present invention before it is subjected to pressure.

[0018] Figure 5 This is the deformation state of the biomimetic foil of the present invention after being compressed.

[0019] Figure 6 This is a schematic diagram of the piezoelectric actuator structure of the present invention.

[0020] Figure 7 This is a schematic diagram of the structure of the top foil of the present invention.

[0021] Figure 8 This is a schematic diagram of the bearing sleeve of the present invention.

[0022] Figure 9 This is a three-dimensional structural diagram of the present invention.

[0023] In the diagram: 1. Bearing sleeve; 11. Connecting plate; 12. Slot; 2. Composite vibration damping part; 21. Bionic foil; 211. Top block; 22. Piezoelectric actuator; 221. Actuation bracket; 222. Piezoelectric ceramic; 23. Connecting beam; 3. Top foil. Detailed Implementation

[0024] The embodiments of the present invention are described in detail below.

[0025] See Figures 1-3 A biomimetic gas foil bearing with an M-shaped bird leg includes a bearing sleeve 1, a composite damping part 2, and a top foil 3. The bearing sleeve 1 is cylindrical, and the top foil 3 is a cylinder with an axial opening and a C-shaped main body. A connecting plate 11 is fixedly installed inside the bearing sleeve 1. One side of the opening of the top foil 3 is detachably fixedly connected to the end of the connecting plate 11 away from the bearing sleeve 1. The top foil 3 is disposed inside the bearing sleeve 1, and a composite damping part 2 is disposed between the top foil 3 and the bearing sleeve 1. The composite damping part 2 consists of several foil groups arranged in a ring, and each foil group consists of multiple biomimetic foils 21. Each foil group corresponds to a piezoelectric actuator 22, which is installed at the end of the foil group near the bearing sleeve 1.

[0026] This invention mimics the "M-shaped" skeletal structure of a bird's lower limbs to design the foil group in the composite vibration damping section 2, achieving excellent mechanical properties of "high static stiffness and low dynamic stiffness", significantly improving the bearing's load-bearing stability and low-frequency vibration isolation capability.

[0027] See Figures 1-5 , Figures 7-8Each foil group comprises several biomimetic foils 21 stacked together, which are fixedly connected together by connecting beams 23 to form a foil group. The biomimetic foil 21 has two legs and two tips. The overall structure of the biomimetic foil 21 is M-shaped. A top block 211 is fixedly connected to the middle position of the upper side of the biomimetic foil 21. The end of the top block 211 is arc-shaped. In the composite damping part 2, the end of the top block 211 contacts and adheres to the outer wall of the top foil 3. When the top foil 3 is subjected to radial pressure, the biomimetic foil 21 undergoes elastic deformation. The ends of the two legs of the biomimetic foil 21 move away from each other, while the two tips of the M-shape approach the top block 211. The several foil groups rotate around the central axis of the bearing sleeve 1 to form the main body of the composite damping part 2. There is a gap between each pair of adjacent foil groups. A slot 12 is provided on the inner side wall of the bearing sleeve 1, and the legs of the biomimetic foil 21 in the foil group are inserted into the slot 12.

[0028] Under stable navigation or static load conditions, the biomimetic foils 21 that make up the foil assembly form a geometrically stable rigid whole, exhibiting high static stiffness characteristics. This effectively supports the self-weight load of the rotor and the ship's power system, resists the continuous change in gravity direction caused by the ship's swaying, and prevents structural buckling instability. When the ship encounters severe sea conditions and experiences low-frequency large-amplitude swaying or wave impact, the geometric nonlinear characteristics of the M-shaped bending structure allow the oblique support section of the biomimetic foil 21 to transform the linear transmission of radial vibration load into a broken line transmission. This achieves multiple load dispersion and buffering at the connection nodes, thereby significantly reducing the transmission efficiency of low-frequency basic excitation to the air film and exhibiting low dynamic stiffness characteristics under minute vibrations. This structure fundamentally solves the problem of traditional foil bearings being unable to balance stiffness and damping in marine environments and having insufficient low-frequency vibration isolation capabilities. It effectively suppresses the severe fluctuations in air film thickness and rotor rubbing caused by the ship's swaying.

[0029] For the specific deformation trend of the biomimetic foil 21 when the top block 211 is subjected to pressure, please see Figures 4-5 When the legs of the bionic foil 21 begin to move away from each other, the gaps between adjacent foil groups are used to prevent interference between the legs when the bionic foil 21 deforms.

[0030] See Figures 1-2 , Figure 6The piezoelectric actuator 22 is fixedly installed between two legs of the corresponding foil group. The piezoelectric actuator 22 includes an actuator bracket 221 and a piezoelectric ceramic 222. The actuator bracket 221 is a rhomboid frame. The piezoelectric ceramic 222 is fixedly installed on the inner side of the actuator bracket 221. The two ends of the piezoelectric ceramic 222 are fixedly connected to the two opposite vertices of the inner side of the actuator bracket 221, respectively. The other two vertices of the actuator bracket 221 are respectively facing the foil group and the inner wall of the bearing sleeve 1. The vertices closer to the inner wall of the bearing sleeve 1 are fixedly connected to the inner wall of the bearing sleeve 1. A pressure sensor is also provided inside the piezoelectric ceramic 222. The pressure sensor is electrically connected to the external control module, and the piezoelectric ceramic 222 is also electrically connected to the external control module.

[0031] The composite vibration damping section 2 of this invention adopts the adaptive contraction characteristics of the piezoelectric actuator 22, which mimics the leg muscle tissue of birds. When the ship encounters transient strong impacts such as underwater asymmetric loads, wave impacts, or power system start-up / braking, the piezoelectric ceramic 222 in the piezoelectric actuator 22, with its millisecond-level fast response, high stiffness, and instantaneous output characteristics, works in conjunction with a pressure sensor and an external control module to quickly sense the impact vibration of the rotor and generate instantaneous micro-displacement compensation based on the control signal. This compensation action can quickly adjust the support shape of the biomimetic foil 21 and actively change the air film pressure distribution, thereby effectively suppressing the instantaneous large-amplitude vibration and subsynchronous vibration phenomena caused by the impact. This dynamic feedback adjustment mechanism enables the bearing to maintain stable operation under complex sea conditions and wide-range variable operating conditions, solving the core bottleneck of traditional passive foil bearings, which are limited by the inherent structural characteristics in terms of adjustment capability and have serious insufficient adaptability when facing multi-source excitation in the ocean.

[0032] Specifically, when the rotor vibrates, the pressure sensor inside the piezoelectric ceramic 222 senses the intensity of the vibration and outputs different electrical signals to the control module. After the control module completes the calculation, it feeds back the corresponding electrical signal to the piezoelectric ceramic 222. The piezoelectric ceramic 222 deforms to different degrees according to the strength of the electrical signal. When the piezoelectric ceramic 222 contracts, the actuator bracket 221 deforms accordingly, pressing the bionic foil 21 towards the top foil 3, so that the top foil 3 exhibits high stiffness in the direction of vibration, effectively solving the problem of insufficient adaptability of traditional foil bearings to wide range of variable working conditions.

[0033] Since the top foil 3 is an elastic support structure, it can undergo local elastic deformation with the air film pressure, thereby changing the air film thickness distribution. Through fluid-structure interaction, it can smooth and reshape the pressure field. When the rotor rotates and the air film pressure increases, the pressure is transmitted through the top foil 3 to the top block 211 of the bionic foil 21. The higher the pressure, the more the local part of the top block 211 is pressed down, and the greater the local air film thickness. During this process, the piezoelectric actuator 22 monitors and adjusts the local stiffness of the top foil 3 in real time, thereby changing the air film pressure distribution. Through this dynamic and feedback adjustment, the instantaneous large-amplitude vibration caused by the impact is effectively suppressed.

[0034] The entire inner gap of the bearing sleeve 1 is filled with damping material.

[0035] This invention effectively improves the overall damping characteristics of the bearing-rotor system by filling all the gaps inside the bearing sleeve 1 with damping material, significantly suppressing the self-excited vibration and subsynchronous vibration induced by the air film, and widening the stable operating speed range of the system. At the same time, the damping material support layer can also improve the dynamic stiffness matching between the top foil 3 and the biomimetic foil 21, reduce the resonance peak value, reduce the dynamic impact load, improve the fatigue life of the structure, and play a buffering and compensation role for working conditions such as assembly errors and rotor misalignment, thereby enhancing the smoothness and reliability of bearing operation.

[0036] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention, which are still covered within the protection scope of the present invention.

Claims

1. A biomimetic gas foil bearing with an M-shaped bird leg, characterized in that, Includes bearing sleeve (1), composite vibration damping part (2), and top foil (3); The bearing sleeve (1) is cylindrical, and the top foil (3) is a cylinder with an axial opening. The main body is C-shaped. A connecting plate (11) is fixedly installed inside the bearing sleeve (1). One side of the opening of the top foil (3) is detachably fixedly connected to the end of the connecting plate (11) away from the bearing sleeve (1). The top foil (3) is located inside the bearing sleeve (1), and a composite vibration damping part (2) is provided between the top foil (3) and the bearing sleeve (1). The composite damping part (2) consists of several foil groups arranged in a ring, and each foil group consists of multiple biomimetic foils (21); Each of the foil groups corresponds to a piezoelectric actuator (22), which is installed at one end of the foil group near the bearing sleeve (1); Each of the foil groups comprises a plurality of biomimetic foils (21) stacked together, which are fixedly connected together by connecting beams (23) to form a foil group; The bionic foil (21) has two legs and two tips. The overall structure of the bionic foil (21) is M-shaped. A top block (211) is fixedly connected to the middle position on the upper side of the bionic foil (21). The end of the top block (211) is arc-shaped. In the composite damping part (2), the end of the top block (211) contacts and adheres to the outer wall of the top foil (3). When the top foil (3) is subjected to radial pressure, the bionic foil (21) undergoes elastic deformation. The ends of the two legs of the bionic foil (21) move away from each other, while the two tips of the M shape approach the top block (211).

2. The M-shaped bird leg biomimetic gas foil bearing according to claim 1, characterized in that, The plurality of foil groups rotate around the central axis of the bearing sleeve (1) to form the main body of the composite damping part (2), with gaps between adjacent foil groups.

3. The M-shaped bird leg biomimetic gas foil bearing according to claim 1, characterized in that, The bearing sleeve (1) has a slot (12) on its inner side wall, and the legs of the bionic foil (21) in the foil group are inserted into the slot (12).

4. The M-shaped bird leg biomimetic gas foil bearing according to claim 3, characterized in that, The piezoelectric actuator (22) is fixedly installed between the two legs of the corresponding foil group.

5. The M-shaped bird leg biomimetic gas foil bearing according to claim 4, characterized in that, The piezoelectric actuator (22) includes an actuator bracket (221) and a piezoelectric ceramic (222). The actuator bracket (221) is a rhomboid frame. The piezoelectric ceramic (222) is fixedly installed on the inner side of the actuator bracket (221). The two ends of the piezoelectric ceramic (222) are fixedly connected to the two opposite vertices of the inner side of the actuator bracket (221). The other two vertices of the actuator bracket (221) are respectively facing the foil group and the inner wall of the bearing sleeve (1). The vertices close to the inner wall of the bearing sleeve (1) are fixedly connected to the inner wall of the bearing sleeve (1).

6. The M-shaped bird leg biomimetic gas foil bearing according to claim 5, characterized in that, The piezoelectric ceramic (222) is also equipped with a pressure sensor, which is electrically connected to an external control module. The piezoelectric ceramic (222) is also electrically connected to an external control module.

7. The M-shaped bird leg biomimetic gas foil bearing according to claim 6, characterized in that, The entire inner gap of the bearing sleeve (1) is filled with damping material.

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