Piezoelectrically actuated active squeeze film damper tilting pad bearing and method for controlling squeeze effect based thereon

Abstract

This invention belongs to the field of sliding bearing technology, and relates to a piezoelectrically actuated actively squeezed oil film damping tilting pad bearing and a method for controlling the squeezed effect based on it. The bearing includes a housing, a bearing body, multiple tilting pads, a preload mechanism, an active adjustment assembly, and a detachable wedge-shaped centering mechanism. The housing has an oil reservoir, and a squeezed oil film thickness layer is formed between the bearing body and the housing. The tilting pads contact the bearing body via spherical supports. The preload mechanism provides preload force, and the piezoelectric ceramic in the active adjustment assembly finely adjusts the squeezed damping effect through radial extension and retraction. The preload screw has a hollow channel for the lead wire to pass through, and the wedge-shaped centering mechanism ensures uniform oil film gap during initial assembly. This invention integrates piezoelectric actuation and squeezed oil film damping, combined with its advanced control algorithm, to actively regulate the squeezed effect, improve rotor system stability, reduce wear, and adapt to variable operating conditions.

Description

Technical Field

[0001] This invention belongs to the field of sliding bearing technology, specifically relating to a piezoelectrically actuated active extrusion oil film damping tilting pad bearing and a method for controlling the extrusion effect based thereon. Background Technology

[0002] Tilting pad bearings are widely used in high-speed rotating machinery due to their excellent stability, vibration resistance, and load-bearing capacity. However, their damping characteristics are usually passive and fixed, and cannot be adaptively adjusted according to the rotor system's operating conditions. When the rotor system encounters sudden disturbances or changes in operating conditions, problems such as increased vibration and decreased stability are likely to occur, seriously affecting the operational reliability and service life of the equipment.

[0003] Currently, to improve system damping and vibration reduction capabilities, tilting pad bearings are often combined with extruded oil film dampers in engineering, utilizing the viscous shear of the oil film to dissipate vibration energy. However, existing extruded oil film damped tilting pad bearings still have many technical shortcomings: Firstly, its oil film gap is a fixed structure, which makes it impossible to achieve real-time active adjustment of damping parameters, making it difficult to adapt to the dynamic operation requirements of the rotor system. Secondly, due to the influence of machining accuracy and assembly process errors, the uniformity of the initial oil film gap in the traditional structure is difficult to guarantee, and the stability of the bearing preload is poor, which greatly reduces the vibration damping effect of the squeeze oil film damper.

[0004] In summary, the aforementioned problems limit the damping control capability of existing extrusion oil film damping tilting pad bearings, making it impossible to meet the high stability and high precision operation requirements of high-speed rotating mechanical rotor systems under complex working conditions. Summary of the Invention

[0005] The purpose of this invention is to provide a piezoelectrically actuated active compression oil film damping tilting pad bearing and a method for controlling the compression effect based on it, aiming to solve the problems in the prior art where the initial installation of the bearing is prone to static eccentricity, the preload is unstable, and the damping characteristics cannot be actively controlled and adjusted in real time.

[0006] This invention is achieved through the following technical solution: This invention discloses a piezoelectrically actuated actively squeezed oil film damping tilting pad bearing, comprising: The outer casing has multiple oil storage chambers circumferentially arranged on its inner wall; A bearing body is coaxially disposed within the outer casing, and an extrusion oil film thickness layer is formed between the outer arc surface of the bearing body and the inner arc surface of the outer casing; Multiple tiltable pads are evenly arranged on the inner arc surface of the bearing body along the circumferential direction, and the back of each tiltable pad contacts the bearing body through a spherical support; And a preload mechanism and an active adjustment assembly radially disposed between the outer casing and the bearing body; The pre-tightening mechanism includes a pre-tightening screw that passes radially through the outer casing, a guide washer and a disc spring sleeved at the end of the pre-tightening screw, and a guide sleeve abutting against the disc spring, with the disc spring sleeved on the guide washer; The active adjustment component includes a piezoelectric ceramic disposed between the guide sleeve and the bearing body. The piezoelectric ceramic is used to generate expansion and contraction deformation and transmit it to the bearing body to realize real-time fine adjustment of the thickness of the squeezed oil film layer. The preload screw has a hollow channel at its center, and the piezoelectric ceramic is connected to an external control circuit through a lead wire passing through the hollow channel.

[0007] Furthermore, the outer casing is provided with an oil inlet hole communicating with the oil storage cavity; the bearing body is provided with an oil spray nozzle, the diameter of which is smaller than the diameter of the oil inlet hole. After the lubricating oil fills the oil reservoir through the oil inlet and compresses the oil film thickness layer, it is throttled and delivered to the tilting pads and rotor journal surfaces through the oil spray nozzle, forming a stable lubrication and cooling circuit.

[0008] Furthermore, end caps are provided at both ends of the outer casing, and the end caps are sealed to the outer casing by bolts.

[0009] The oil reservoir between the outer shell and the bearing body is also equipped with a detachable wedge-shaped centering mechanism for initial installation centering.

[0010] Furthermore, the wedge block centering mechanism includes an upper wedge block, a lower wedge block, a long screw, and a nut; a groove is pre-made on the inclined surface of the lower wedge block; the upper wedge block and the lower wedge block are in contact and engaged through the inclined surface and the groove; the long screw passes through the upper wedge block and the lower wedge block, and is adjusted by the threaded engagement with the nut, driving the two wedge blocks to slide relative to each other to adjust the height, ensuring that the thickness of the circumferentially compressed oil film layer is uniform in height in the initial state.

[0011] Furthermore, a first limiting groove is machined at the center position of the inner arc surface of the outer shell opposite to the oil storage cavity, and a second limiting groove is provided at the corresponding position of the outer arc surface of the bearing. The wedge block centering mechanism is installed between the first limiting groove and the second limiting groove.

[0012] Furthermore, two symmetrical radial threaded holes are machined on the outer shell area corresponding to each oil storage cavity, and the preload screw is threaded into the radial threaded hole; the end of the preload screw axially abuts against the guide washer, and the end of the disc spring away from the guide washer abuts against the end face of the guide sleeve.

[0013] Furthermore, the guide sleeve has a stepped hollow structure, including a large-diameter section and a small-diameter section; the inner hole of the large-diameter section is used to accommodate the disc spring; the inner hole of the small-diameter section matches the outer diameter of the piezoelectric ceramic to guide the axial extension and retraction of the piezoelectric ceramic.

[0014] Furthermore, the active adjustment assembly also includes a pad and an adjusting shim, which are fixed in the outer arc groove of the bearing body by screws; the piezoelectric ceramic is assembled in the mounting groove of the pad, and the piezoelectric ceramic, guide sleeve, disc spring and preload screw are on the same radial axis.

[0015] This invention also discloses a method for controlling the squeezing effect in a piezoelectrically actuated active squeezing oil film damping tilting pad bearing, comprising the following steps: Input the desired displacement, and use the feedforward compensator to calculate the initial voltage that theoretically needs to be applied to achieve the desired displacement; When an initial voltage signal is applied to the piezoelectric ceramic, the piezoelectric ceramic undergoes expansion and contraction deformation, and the amount of deformation is transmitted to the bearing body. The sensor measures the piezoelectric ceramic driven displacement in real time, obtains the displacement error based on the expected displacement and the piezoelectric ceramic driven displacement, and determines whether the displacement error exceeds the preset threshold. If the preset threshold is not exceeded, the current input voltage is maintained, and displacement is monitored in real time. If the displacement error exceeds the preset threshold, the displacement error signal is input to the integral feedback controller to calculate the correction voltage that needs to be compensated. The initial voltage and the correction voltage are added together to obtain the total input voltage applied to the piezoelectric ceramic. After applying the total input voltage, the piezoelectric ceramic is driven to move again. Through multiple iterations, the displacement error is updated until it stabilizes and converges to the preset threshold range.

[0016] Furthermore, the calculation process for the corrected voltage is as follows: The particle swarm optimization intelligent algorithm is used to optimize the integral gain parameter online to obtain the optimal integral gain. ; The optimized integral gain The voltage is updated in real time to the integral feedback controller for calculating the correction voltage; The calculation expression for the integral feedback controller is:

[0017] in, The correction voltage for integral feedback; τ Let be the integration time variable, representing any point in time between the initial moment and the current moment t; For integration time variable τ The corresponding displacement error.

[0018] Compared with the prior art, the present invention has the following beneficial technical effects: This invention discloses a piezoelectrically actuated, actively squeezed oil film damping tilting pad bearing. By integrating a housing, bearing body, tilting pads, preload mechanism, active adjustment assembly, and wedge block centering mechanism, an actively controlled tilting pad bearing structure is constructed that combines piezoelectric actuation with squeezed oil film damping. This effectively solves the technical pain points of traditional tilting pad bearings, such as poor damping controllability, limited vibration suppression capability, and insufficient assembly precision. The specific technical effects are as follows: Multiple oil storage chambers arranged circumferentially on the inner wall of the outer shell can achieve stable storage and supply of lubricating oil, ensuring the stable formation of the extrusion oil film thickness layer, significantly improving the stiffness and damping stability of the extrusion oil film, and providing reliable damping support for the rotor system. The compression oil film thickness layer formed between the bearing housing and the outer housing generates additional damping through the oil film compression effect, which can effectively suppress the vibration amplitude of the rotor during operation, improve the operating stability of the rotor system, and reduce the risk of rotor instability. The tilting pads contact the bearing housing through spherical support, allowing the pads to tilt freely. This adapts to the runout and misalignment of the rotor journal, reducing friction and wear between the pads and the journal, lowering operating noise, and extending the bearing's service life. The pre-tightening mechanism, through the cooperation of pre-tightening screws, guide washers, disc springs, and guide sleeves, provides pre-tightening force to the piezoelectric ceramic, ensuring that the piezoelectric ceramic is always within its effective working range and preventing loosening, unloading, or stress concentration during expansion and contraction, thus guaranteeing the stable realization of the active adjustment function. This invention precisely adjusts the compression of the disc spring by rotating the pre-tightening screw, providing a stable and controllable radial pre-tightening force to the bearing body, ensuring that the pre-tightening state is maintained even after the wedge block mechanism is removed. Simultaneously, the adjusting shims located below the pads not only assist in fine-tuning the pre-tightening force but also effectively compensate for the elongation displacement of the piezoelectric ceramic, preventing pre-tightening failure due to piezoelectric ceramic deformation. This invention utilizes the electrical expansion and contraction properties of piezoelectric ceramics, enabling rapid response to external control signals and precise axial deformation. The deformation force is efficiently transmitted to the bearing body via the piezoelectric ceramics, allowing the bearing to adjust the thickness of the squeeze oil film and the support stiffness in real time during operation. This significantly improves the dynamic response capability and vibration suppression effect of the bearing in response to changes in the operating conditions of the rotor system and sudden disturbances.

[0019] The hollow channel in the center of the preload screw allows for concealed arrangement of the leads, ensuring a reliable connection between the piezoelectric ceramic and the external control circuit, while also optimizing the overall structural layout of the bearing. This prevents lead wear or interference with the internal movement of the bearing, providing a structural basis for achieving closed-loop active control of the bearing.

[0020] Furthermore, the diameter of the oil injection port on the bearing housing is smaller than that of the oil inlet, creating a throttling effect. This allows for precise control of the lubricating oil injection flow rate and pressure, ensuring that the lubricating oil is sprayed onto the tilting pads and rotor journal surfaces at an appropriate flow rate and pressure, guaranteeing uniform and sufficient lubrication for the tilting pad sliding pair. Through the synergistic effect of the oil inlet, oil reservoir, compressed oil film thickness layer, and oil injection port, a complete "oil inlet—oil reservoir—oil film damping—throttling lubrication—cooling" circuit is formed. This not only ensures the stable operation of the compressed oil film damping but also effectively removes the heat generated during bearing operation, reducing bearing temperature rise and preventing problems such as lubricating oil deterioration and accelerated bearing wear caused by overheating. This further extends the bearing's service life and improves its operational reliability.

[0021] Furthermore, this invention introduces a detachable wedge-shaped centering mechanism. Utilizing the precise cooperation of a long screw and nut, the upper and lower wedges slide relative to each other, enabling precise adjustment of the relative position between the bearing body and the outer shell during the initial bearing installation stage. This ensures a uniform initial gap in the circumferentially compressed oil film, forcibly eliminating static eccentricity and solving the problem of uneven oil film thickness distribution caused by assembly errors in traditional structures. The detachable wedge-shaped centering mechanism is used for centering and calibration during initial bearing installation, effectively eliminating assembly errors and ensuring a uniform circumferential height of the compressed oil film thickness layer in the initial state. This improves the assembly accuracy and consistency of the bearing. Moreover, it can be removed after assembly without interfering with the normal operation of the bearing, balancing assembly convenience and operational reliability.

[0022] Furthermore, the first limiting groove on the outer shell corresponds to the second limiting groove on the bearing body, which can accurately position the wedge block centering mechanism in the circumferential and radial directions, effectively preventing the centering mechanism from moving during assembly adjustment and initial test run of the bearing, and ensuring centering accuracy. The limiting groove is set at the center of the inner arc surface of the outer shell opposite the oil reservoir, so that the centering mechanism can be located in the symmetrical center area of ​​the bearing, and the force is uniform during adjustment, which can ensure the overall coaxiality of the oil film gap and further improve the assembly accuracy. This invention constructs a nonlinear mathematical model based on the hysteresis characteristics of piezoelectric ceramics, and further introduces a feedforward compensator based on Fourier analysis to perform inverse model compensation for the hysteresis nonlinearity of the piezoelectric ceramics. Combined with an integral feedback controller for closed-loop correction of displacement errors, and employing an intelligent optimization algorithm to perform online optimization of key controller parameters, a composite control strategy is formed. This control method effectively suppresses the hysteresis nonlinearity of the piezoelectric ceramics during the driving process, improves the linearity of the control output and the dynamic response speed, enabling the bearing system to precisely adjust the squeezing effect according to the real-time operating conditions of the rotor, thereby significantly improving the operational stability of the rotor system. Attached Figure Description

[0023] Figure 1This is a schematic diagram of the piezoelectrically actuated active extrusion oil film damping tilting pad bearing with wedge block centering mechanism of the present invention; Figure 2 This is an exploded view of the structure of the piezoelectrically actuated actively squeezed oil film damping tilting pad bearing with bearing end cap of the present invention; Figure 3 This is a cross-sectional view of the piezoelectrically actuated actively squeezed oil film damping tilting pad bearing of the present invention; Figure 4 for Figure 3 An enlarged schematic diagram of part A; Figure 5 This is a schematic diagram of the structure of the piezoelectrically actuated actively squeezed oil film damping tilting pad bearing housing of the present invention; Figure 6 This is a schematic diagram of the wedge block centering mechanism of the present invention; Figure 7 This is a block diagram of the control system of the present invention.

[0024] Explanation of reference numerals in the attached figures: 1. Outer shell; 2. Guide sleeve; 3. Bearing body; 4. Tilting pad; 5. Upper wedge block; 6. Long screw; 7. Lower wedge block; 8. Preload screw; 9. End cap; 10. Lead wire; 11. Bolt; 12. Guide washer; 13. Disc spring; 14. Piezoelectric ceramic; 15. Pad; 16. Screw; 17. Extrusion oil film thickness layer; 18. Spherical support; 19. Spring washer; 20. Adjusting shim; 21. Circular washer; 22. Nut; 101. First connecting hole; 102. Axial threaded hole; 103. Oil inlet hole; 104. Oil reservoir; 105. First limiting groove; 106. Radial threaded hole; 107. Second connecting hole; 301. Fuel injector; 302. Second limiting groove; 701. Groove; 901, Third connecting hole. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of the present invention clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention; that is, the described embodiments are only a part of the embodiments of the present invention, and not all of them.

[0026] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0027] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0028] The present invention will be further explained below with reference to the accompanying drawings: like Figures 1-3 As shown, the present invention provides a piezoelectrically actuated active compression oil film damping tilting pad bearing, which mainly includes a housing 1, a bearing body 3, tilting pads 4, an end cap 9, and a pre-tightening mechanism and an active adjustment assembly radially disposed between the housing 1 and the bearing body 3.

[0029] like Figure 3 As shown, the inner wall of the outer casing 1 is uniformly provided with four oil storage chambers 104 along the circumference for storing lubricating oil; the bearing body 3 is coaxially installed inside the outer casing 1, and a small extrusion oil film thickness layer 17 is formed between the outer arc surface of the bearing body 3 and the inner arc surface of the outer casing 1, which is filled with lubricating oil to provide damping; four tilting pads 4 are uniformly spaced along the circumference on the inner arc surface of the bearing body 3, and the back of each tilting pad 4 is engaged with the spherical groove of the bearing body 3 through a spherical support 18, so that the tilting pad 4 can swing around the pivot point according to the rotor operating conditions.

[0030] like Figure 2 and Figure 5 As shown, the outer shell 1 adopts a split structure, including two symmetrically connected semi-circular shells. Two support blocks are integrally machined on the inner arc surface of the semi-circular shells, and an oil storage cavity 104 is formed between the two adjacent support blocks.

[0031] Radial threaded holes 106 are symmetrically opened on both sides of the support block, and the radial threaded holes 106 are connected to the oil storage cavity 104.

[0032] End caps 9 are installed at both axial ends of the outer shell 1. Multiple axial threaded holes 102 are opened along the circumferential direction of the side wall of the semi-circular shell. The end caps 9 are fastened to the axial threaded holes 102 of the outer shell 1 by bolts 11 passing through the third connecting hole 901. The end caps 9 are used in conjunction with the sealing gasket to achieve axial sealing and prevent lubricating oil leakage. like Figure 5 As shown, the outer shell 1 has an oil inlet hole 103 that communicates with the oil storage cavity 104; a first limiting groove 105 is machined at the center of the inner arc surface of the outer shell 1 opposite to the oil storage cavity 104 for conveying lubricating oil into the cavity.

[0033] Semicircular oil inlet holes are provided on both connecting end faces of the semicircular shell. When the two semicircular shells are spliced ​​together, a complete oil inlet hole 103 is formed at the connecting end face.

[0034] like Figure 1 As shown, the upper housing has pre-drilled first connecting holes 101 arranged longitudinally at both ends, as... Figure 5 As shown, the two end faces of the lower housing and the upper housing that abut against each other are pre-made with second connecting holes 107. The second connecting holes 107 are threaded holes. The upper housing and the lower housing are threadedly fastened together through the first connecting hole 101 and the second connecting hole 107. A sealing structure is provided on the mating surface.

[0035] like Figure 3 As shown, an oil spray port 301 is provided at a corresponding position on the bearing housing 3. Based on the principle of orifice throttling, the orifice diameter of the oil spray port 301 is configured to be significantly smaller than the orifice diameter of the oil inlet 103, and the design flow rate of a single oil spray port 301 is approximately one-quarter of the total oil required by the bearing. After the lubricating oil fills the oil storage chamber 104 and the oil film thickness layer 17 through the oil inlet 103, it is throttled and delivered to the tilting pad 4 and the rotor journal surface through the oil spray port 301, forming a stable lubrication and cooling circuit.

[0036] like Figure 4 As shown, a second limiting groove 302 is machined on the outer circumferential surface of the bearing body 3, and the second limiting groove 302 is disposed opposite to the first limiting groove 105. The oil injection port 301 is located at the center of the second limiting groove 302.

[0037] like Figure 4 As shown, a detachable wedge-shaped centering mechanism is provided between the first limiting groove 105 in the oil storage cavity 104 and the second limiting groove 302 on the bearing body 3. This mechanism is used to adjust the concentricity of the bearing body 3 and the outer shell 1 during initial installation and to facilitate disassembly after the bearing reaches a balanced state.

[0038] like Figure 6As shown, the wedge block centering mechanism includes an upper wedge block 5 and a lower wedge block 7. A groove 701 is pre-formed on the inclined surface of the lower wedge block 7. The upper wedge block 5 and the lower wedge block 7 are guided and engaged with the groove 701 through their inclined surfaces to prevent misalignment. Both the upper wedge block 5 and the lower wedge block 7 have central holes machined inside. A long screw 6 passes through the central holes of both the upper wedge block 5 and the lower wedge block 7. A circular washer 21 and a nut 22 are fitted onto one end of the long screw 6. During initial installation, the upper wedge block 5 and the lower wedge block 7 slide relative to each other by tightening the external nut 22, thereby changing the radial height of the mechanism. By coordinating the adjustment of the wedge block mechanisms in four directions, the bearing body 3 can be precisely aligned to the geometric center of the outer shell 1, ensuring that the circumferentially compressed oil film thickness layer 17 has a uniform height in the initial state, eliminating static eccentricity.

[0039] The specific principle is as follows: the long screw 6 is rigidly connected to the lower wedge block 7. When the nut 22 is rotated, the nut 22 drives the lower wedge block 7 to move axially (horizontally). When the lower wedge block 7 moves axially, it will slide relative to the upper wedge block 5. Since the contact surface is an inclined plane, this relative sliding in the horizontal direction will be converted into a displacement in the vertical direction: if the lower wedge block 7 moves to the side with higher inclination, the upper wedge block 5 will descend, and the radial height of the mechanism will decrease; if the lower wedge block 7 moves to the side with lower inclination, the upper wedge block 5 will rise, and the radial height of the mechanism will increase.

[0040] like Figure 3 and Figure 4 As shown, the preload mechanism and the active adjustment component are sequentially connected in series within the radial hole of the housing 1. The preload mechanism includes a preload screw 8, a spring washer 19, a guide washer 12, a disc spring 13, and a guide sleeve 2, used to provide a stable radial preload force to the bearing body 3. The preload screw 8 is screwed into the radial threaded hole 106 of the housing 1; the fine thread and the matching spring washer 19 prevent loosening of the thread. The end of the preload screw 8 inserts into and abuts against the guide washer 12, thereby compressing the disc spring 13 sleeved on the outer periphery of the guide washer 12. The end of the disc spring 13 away from the guide washer 12 abuts against the guide sleeve 2, ensuring a uniform and stable transmission of the preload force.

[0041] After the wedge block mechanism is initially centered, each preload screw 8 is rotated sequentially using an external torque wrench. The disc spring 13 is compressed through the guide washer 12. The deformation of the disc spring 13 is adjusted according to the torque value to precisely control the magnitude of the preload. Due to the installation angle, the preload setting of the preload mechanism located on both sides of the lowest oil reservoir 104 of the bearing should additionally compensate for the influence of the bearing load. The compression deformation of the disc spring 13 should not exceed half of the initial value of the squeezed oil film thickness layer 17 to avoid rigid contact between the inner arc surface of the outer shell 1 and the outer arc surface of the bearing body 3, which would lead to oil film failure. After preload is completed, the wedge block centering mechanism is removed. The elastic force of the disc spring 13 continues to provide a stable radial preload to the bearing body 3, maintaining the initial balance state of the squeezed oil film thickness layer 17.

[0042] like Figure 3 and Figure 4 As shown, the active adjustment assembly includes a piezoelectric ceramic 14, a pad 15, and an adjusting shim 20, sequentially arranged between the guide sleeve 2 and the bearing body 3. The guide sleeve 2 is designed as a stepped hollow structure, with its large-diameter inner hole accommodating a disc spring 13 to ensure coaxiality of the preload; its small-diameter inner hole precisely matches the outer diameter of the piezoelectric ceramic 14, guiding the axial expansion and contraction of the piezoelectric ceramic 14 and ensuring accurate axial transmission of its deformation force. The piezoelectric ceramic 14 is installed in the groove of the pad 15, and the pad 15 and the adjusting shim 20 are fixed to the outer arc groove of the bearing body 3 by screws 16. Furthermore, the preload screw 8, the disc spring 13, the guide sleeve 2, and the piezoelectric ceramic 14 are on the same radial axis, ensuring coaxiality of force transmission; the adjusting shim 20 can be selected and used in different specifications according to assembly requirements, on the one hand to assist in fine-tuning the preload, and on the other hand to compensate for the elongation displacement of the piezoelectric ceramic 14, eliminating manufacturing and assembly errors.

[0043] The preload screw 8 has a hollow channel at its center, through which the lead wire 10 of the piezoelectric ceramic 14 passes to connect to the external control circuit. The circuit includes components such as resistors and inductors for generating electromechanical coupling resonance and applying electrical energy, ensuring the stability of electromechanical coupling. When an external voltage is applied, the piezoelectric ceramic 14 undergoes expansion and contraction deformation. This deformation is transmitted to the bearing body 3 through the pad 15 and the adjusting shim 20, thereby achieving real-time fine adjustment of the thickness layer 17 of the squeezed oil film, and thus actively regulating the bearing damping.

[0044] To effectively control the squeezing effect, this invention designs a control algorithm, including the following steps: 1) Rotor operating parameters are acquired in real time using external sensors. The desired displacement is determined by monitoring the rotor's operating status. To accurately describe the nonlinear strain behavior of the piezoelectric ceramic 14 under an electric field, a mathematical model of the following form is established to characterize the hysteresis relationship between its electric field strength and axial strain: (1) in, ε For piezoelectric ceramic strain; E Electric field strength; d It is a linear piezoelectric constant; λ It is a nonlinear hysteresis parameter; E a The amplitude of the applied electric field is represented by "+" and "-", which correspond to the electric field loading and unloading processes, respectively.

[0045] 2) Based on the strain model in formula (1) above, and combined with the piezoelectric stack structure parameters, a nonlinear relationship model of the displacement response of piezoelectric ceramic 14 under voltage excitation is established: (2) in, x ( t ) represents the displacement driven by the piezoelectric ceramic; U This is the total input voltage; U a This refers to the amplitude of the driving voltage. m The number of piezoelectric layers; δ The thickness is the piezoelectric ceramic.

[0046] 3) When the total input voltage is a periodic sine wave U = U a sin( ωt When ), U = U a sin( ωt Substituting into formula (2) and using Fourier series expansion, we obtain the multi-frequency component expression of the displacement response as shown in formula (3): (3) in, ω is the angular frequency of the rotor; t For time. Based on formula (3), the inverse mapping relationship of the piezoelectric actuation system can be further constructed, and a feedforward compensator can be designed accordingly to weaken the influence of hysteresis nonlinearity on the system response and improve the output linearity.

[0047] Sine waves are the most common form of vibration in rotating machinery and are also convenient for constructing feedforward compensators to suppress hysteresis. If the input voltage is not a sine wave, the expansion of formula (3) will be different, but the core idea of ​​step 3) still applies. It is just that different modeling or compensation methods need to be used according to the actual input waveform to obtain the feedforward compensator.

[0048] like Figure 7As shown, in practical applications, the desired displacement is first input, and the initial voltage that needs to be applied to achieve this desired displacement is calculated by the feedforward compensator; the initial voltage signal is applied to the piezoelectric ceramic 14 to cause it to expand and contract, and the amount of deformation is transmitted to the bearing body 3. The displacement sensor measures the piezoelectric ceramic driven displacement of the piezoelectric ceramic 14 in real time, and obtains the displacement error based on the expected displacement and the piezoelectric ceramic driven displacement, and determines whether the displacement error exceeds the preset threshold. If the preset threshold is not exceeded, the current input voltage is maintained, and displacement is monitored in real time. If the displacement error exceeds the preset threshold, the displacement error signal is input to the integral feedback controller to calculate the correction voltage that needs to be compensated. The initial voltage and the correction voltage are added together to obtain the total input voltage applied to the piezoelectric ceramic 14. After applying the total input voltage, the piezoelectric ceramic is driven to move again. Through multiple iterations, the displacement error is updated until it stabilizes and converges to the preset threshold range.

[0049] Specifically, the desired displacement value is determined based on the rotor vibration state or preset damping requirements.

[0050] Specifically, the displacement sensor can be mounted on the outside of the housing 1 and connected to the piezoelectric ceramic 14 via a connecting wire. The connecting wire also passes through the preload screw 8.

[0051] The control algorithm of this invention independently or collaboratively controls the piezoelectric ceramics 14 in all directions, driving displacement through real-time feedback from the piezoelectric ceramics. x ( t For total input voltage U Dynamic correction is performed, and the control circuit adjusts the total input voltage according to the rotor operating conditions. U This drives the piezoelectric ceramic 14 to generate precise axial expansion and contraction deformation. This deformation force is transmitted to the bearing body 3 via the pad 15, enabling real-time precise fine-tuning of the oil film thickness layer 17, thereby actively suppressing rotor vibration.

[0052] The integral feedback controller is a closed-loop regulation algorithm based on classical control theory. Its core idea is to integrate the error between the piezoelectric ceramic driven displacement and the desired displacement, and dynamically correct the driving voltage of the piezoelectric ceramic until the error is completely eliminated.

[0053] Specifically, this invention introduces a particle swarm optimization (PSO) intelligent algorithm to optimize the integral gain parameter online, thereby improving the control accuracy of the squeezing effect and the dynamic response capability of the system.

[0054] The time integral (ITAE) of the absolute value of the error between the piezoelectric ceramic-driven displacement and the desired displacement is used as the fitness function for the particle swarm optimization algorithm: (4) in,J For fitness function values; displacement error e ( t )= x d ( t )- x ( t ); x d ( t () represents the desired displacement; x ( t ) represents the displacement driven by the piezoelectric ceramic; T For evaluation time window.

[0055] The fitness function is used to evaluate the control performance of the integral gain. The smaller the J value, the higher the displacement tracking accuracy and the better the dynamic response of the system.

[0056] In the particle swarm optimization algorithm, the position of each particle corresponds to a candidate integral gain. Particle swarm optimization aims to minimize the fitness function. J With the goal of iteratively updating the particle's velocity and position, the search aims to make... J Minimum optimal integral gain : (5) (6) in, Indicates the first i Particles k The speed of time; Indicates the first i Individual particles k Integral gain at time step; w Inertial weight; c 1 and c 2 is the learning factor, usually c 1= c 2=2; r 1 and r 2 is a random number between [0, 1]; p best represents the optimal value for an individual. g "best" refers to the globally optimal value.

[0057] The optimized integral gain The data is updated in real time to the integral feedback controller for calculating the correction voltage. (7) in, The correction voltage for integral feedback; τ Let be the integration time variable, representing any point in time between the initial moment and the current moment t; For integration time variable τ The corresponding displacement error.

[0058] The corrected voltage, superimposed with the feedforward voltage, drives the piezoelectric ceramic 14, achieving precise adjustment of the extrusion effect. Through this intelligent optimization strategy, the system can adaptively adjust control parameters according to changes in rotor operating conditions, significantly improving vibration suppression and control robustness.

[0059] The working process of this invention is as follows: After the main bearing structure is installed, a wedge block centering mechanism is installed between the first limiting groove 105 in the oil storage cavity 104 and the second limiting groove 302 on the bearing body 3. By rotating the long screw 6 and the nut 22, the upper and lower wedge blocks are driven to move relative to each other, and the radial position of the bearing body 3 is adjusted until the thickness of the extruded oil film layer 17 in the circumferential direction is monitored to be uniform, that is, the preset initial gap is achieved.

[0060] After centering, use a calibrated torque wrench to rotate the preload screws 8 in each direction sequentially, compressing the disc springs 13 to adjust the preload to the preset value. In particular, for the preload mechanisms located on both sides of the oil reservoir 104 at the bottom of the bearing, the preload setting should additionally compensate for the influence of the bearing load. After ensuring that the preload mechanism has provided sufficient stable support, rotate the nut 22 in the opposite direction to remove the wedge block centering mechanism; then install the end caps 9 on both sides of the bearing, turn on the lubrication system, and the lubricating oil fills the oil reservoir 104 and compresses the oil film thickness layer 17 through the oil inlet hole 103, and is sprayed through the oil spray nozzle 301 into the space between the tilting pad 4 and the rotor journal to form a lubricating film.

[0061] During equipment operation, the tilting pads 4 are evenly distributed on the outer periphery of the rotor. The control system monitors the piezoelectric ceramic driving displacement of the piezoelectric ceramic 14 in real time through external sensors. Using the above control algorithm, the piezoelectric ceramic 14 in each position is controlled independently or in a coordinated manner. A voltage signal is applied to the piezoelectric ceramic 14 to generate expansion and contraction deformation. The deformation is transmitted to the bearing body 3 through the pad 15 and the adjusting shim 20, so as to realize the real-time precise fine adjustment of the thickness layer 17 of the squeeze oil film, thereby actively suppressing rotor vibration.

[0062] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can be appropriately combined to form other embodiments that can be understood by those skilled in the art. The above content is only for illustrating the technical concept of the present invention and should not be used to limit the scope of protection of the present invention. Any modifications made to the technical solutions based on the technical concept proposed in this invention fall within the scope of protection of this invention.

Claims

1. A piezoelectrically actuated, actively squeezed oil film damping tilting pad bearing, characterized in that, include: The outer shell (1) has multiple oil storage cavities (104) arranged circumferentially on its inner wall. The bearing body (3) is coaxially disposed inside the outer shell (1), and an extrusion oil film thickness layer (17) is formed between the outer arc surface of the bearing body (3) and the inner arc surface of the outer shell (1). Multiple tiltable tiles (4) are evenly arranged on the inner arc surface of the bearing body (3) along the circumferential direction, and the back of each tiltable tile (4) contacts the bearing body (3) through a spherical support (18); And a preload mechanism and an active adjustment assembly radially disposed between the outer casing (1) and the bearing body (3); The pre-tightening mechanism includes a pre-tightening screw (8) that passes radially through the outer shell (1), a guide washer (12) sleeved on the end of the pre-tightening screw (8), and a disc spring (13) and a guide sleeve (2) that abuts against the disc spring (13), with the disc spring (13) sleeved on the guide washer (12). The active adjustment component includes a piezoelectric ceramic (14) disposed between the guide sleeve (2) and the bearing body (3). The piezoelectric ceramic (14) is used to generate expansion and contraction deformation and transmit it to the bearing body (3) to realize real-time fine adjustment of the oil film thickness layer (17). The pre-tightening screw (8) has a hollow channel in the center, and the piezoelectric ceramic (14) is connected to an external control circuit through a lead wire (10) passing through the hollow channel.

2. The piezoelectrically actuated actively squeezed oil film damping tilting pad bearing according to claim 1, characterized in that, The outer shell (1) is provided with an oil inlet (103) communicating with the oil storage cavity (104); the bearing body (3) is provided with an oil spray port (301), the diameter of the oil spray port (301) is smaller than the diameter of the oil inlet (103); After the lubricating oil fills the oil storage chamber (104) through the oil inlet (103) and squeezes the oil film thickness layer (17), it is throttled and delivered to the tilting pad (4) and the rotor journal surface through the oil spray port (301) to form a stable lubrication and cooling circuit.

3. The piezoelectrically actuated actively squeezed oil film damping tilting pad bearing according to claim 1, characterized in that, The oil reservoir (104) between the outer shell (1) and the bearing body (3) is also equipped with a detachable wedge block centering mechanism for initial installation centering.

4. The piezoelectrically actuated actively squeezed oil film damping tilting pad bearing according to claim 3, characterized in that, The wedge centering mechanism includes an upper wedge (5), a lower wedge (7), a long screw (6), and a nut (22); a groove (701) is pre-made on the inclined surface of the lower wedge (7); the upper wedge (5) and the lower wedge (7) are in contact and engaged through the inclined surface and the groove (701); the long screw (6) passes through the upper wedge (5) and the lower wedge (7) and is adjusted by the thread engagement with the nut (22) to drive the upper wedge (5) and the lower wedge (7) to slide relative to each other to adjust the height, so as to ensure that the circumferentially squeezed oil film thickness layer (17) is uniform in height in the initial state.

5. The piezoelectrically actuated actively squeezed oil film damping tilting pad bearing according to claim 1, characterized in that, The oil storage cavity (104) is located at the center of the inner arc surface of the outer shell (1), and the bearing body (3) is provided with a second limiting groove (302) at the corresponding position on the outer arc surface. The wedge block centering mechanism is installed between the first limiting groove (105) and the second limiting groove (302).

6. The piezoelectrically actuated actively squeezed oil film damping tilting pad bearing according to claim 1, characterized in that, Two symmetrical radial threaded holes (106) are machined on the outer shell (1) area corresponding to each oil reservoir (104), and the preload screw (8) is threaded into the radial threaded hole (106); the end of the preload screw (8) axially abuts against the guide washer (12), and the end of the disc spring (13) away from the guide washer (12) abuts against the end face of the guide sleeve (2).

7. The piezoelectrically actuated actively squeezed oil film damping tilting pad bearing according to claim 6, characterized in that, The guide sleeve (2) is a stepped hollow structure, including a large diameter section and a small diameter section; the inner hole of the large diameter section is used to accommodate the disc spring (13); the inner hole of the small diameter section matches the outer diameter of the piezoelectric ceramic (14) to guide the axial extension and retraction of the piezoelectric ceramic (14).

8. The piezoelectrically actuated actively squeezed oil film damping tilting pad bearing according to claim 1, characterized in that, The active adjustment assembly also includes a pad (15) and an adjusting shim (20), which are fixed in the outer arc groove of the bearing body (3) by screws (16); the piezoelectric ceramic (14) is assembled in the mounting groove of the pad (15), and the piezoelectric ceramic (14), the guide sleeve (2), the disc spring (13) and the preload screw (8) are on the same radial axis.

9. Based on claim 1 The method for controlling the squeezing effect of a piezoelectrically actuated active squeezing oil film damping tilting pad bearing as described in any one of the 8 is characterized in that, Includes the following steps: Input the desired displacement, and use the feedforward compensator to calculate the initial voltage that theoretically needs to be applied to achieve the desired displacement; An initial voltage signal is applied to the piezoelectric ceramic (14), causing the piezoelectric ceramic (14) to undergo expansion and contraction deformation, which is then transmitted to the bearing body (3). Real-time measurement of the piezoelectric ceramic driven displacement, obtaining the displacement error based on the expected displacement and the piezoelectric ceramic driven displacement, and determining whether the displacement error exceeds a preset threshold. If the preset threshold is not exceeded, the current input voltage is maintained, and displacement is monitored in real time. If the displacement error exceeds the preset threshold, the displacement error signal is input to the integral feedback controller to calculate the correction voltage that needs to be compensated. The initial voltage and the correction voltage are added together to obtain the total input voltage applied to the piezoelectric ceramic (14). After applying the total input voltage, the piezoelectric ceramic is driven to move again. Through multiple iterations, the displacement error is updated until it is stably converged to the preset threshold range.

10. The method for controlling the squeezing effect in a piezoelectrically actuated actively squeezing oil film damping tilting pad bearing according to claim 9, characterized in that, The calculation process for the corrected voltage is as follows: The particle swarm optimization intelligent algorithm is used to optimize the integral gain parameter online to obtain the optimal integral gain. ; The optimized integral gain The voltage is updated in real time to the integral feedback controller for calculating the correction voltage; The calculation expression for the integral feedback controller is: in, The correction voltage for integral feedback; τ Let be the integration time variable, representing any point in time between the initial moment and the current moment t; For integration time variable τ The corresponding displacement error.

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