Gap-adjustable sliding bearing structure, bearing rotor system and vibration control method of bearing rotor system

Abstract

The invention discloses a gap-adjustable sliding bearing structure, a bearing rotor system and a vibration control method of the bearing rotor system. The bearing structure comprises two bearing pads and a displacement actuator. The two bearing pads have the same structure and are symmetrically distributed up and down; the displacement actuator enables the bearing pads to slightly move in the vertical direction and the horizontal direction respectively, so that the side clearance and the top clearance of the bearing are adjusted. The displacement actuator is connected with the output end of the PID controller, and the input end of the PID controller is connected with the displacement sensor; the rotor system comprises feedback control of a displacement sensor, a PID (Proportion Integration Differentiation) controller and a displacement actuator, so that active adjustment of a dislocation-elliptical bearing backlash or a top clearance is realized, and finally, suppression of rotor vibration is realized.

Description

Technical Field

[0001] The invention relates to a clearance-adjustable sliding bearing structure, a supporting rotor system and a vibration control method thereof, and belongs to the field of sliding bearings. Background Art

[0002] Dislocation-elliptical radial sliding bearings are used in large rotating machinery such as steam turbines and heavy-duty gas turbines due to their large load-bearing capacity and good stability. Generally, they are composed of two upper and lower bearing pads. The gap between the shaft neck and the bearing pad can be divided into top gap and side gap. The top gap is the gap between the shaft neck and the bearing pad in the vertical direction, while the side gap is the gap between them in the horizontal direction. The radial clearance has an important influence on the vibration characteristics of the mechanical system. There are significant differences in the lubrication performance of the sliding bearing under different radial clearances. The radial clearance of traditional sliding bearings cannot be adjusted in real time. In a complex service environment, the operating state of the sliding bearing-rotor system will be significantly affected by changes in operating parameters such as speed and load.

[0003] In order to adapt to time-varying service conditions and improve the operating stability of rotating machinery, many scholars have proposed a sliding bearing with adjustable top clearance. This type of bearing can improve its lubrication characteristics by changing the top clearance based on the vibration state of the shaft neck using a mechanical transmission structure, and further improve the stability of the rotor system. However, most research work focuses on improving the vibration characteristics of bearings by adjusting the top clearance, and there are few discussions on the influence of bearing side clearance on lubrication characteristics. To this end, the present invention proposes an offset-elliptical radial sliding bearing with adjustable top clearance and adjustable side clearance. This sliding bearing with adjustable top clearance and side clearance is significantly better than a sliding bearing with only an adjustable top clearance in improving the operating state of the rotor system.

[0004] A geometrically adjustable intelligent bearing support device (application number: 201710289838.0) discloses a bearing with only adjustable top clearance, which changes the oil film force acting on the journal by changing the top clearance, thereby achieving the function of regulating the bearing performance. However, this adjustable mechanism has certain limitations, as it can only adjust the vertical top clearance, while the horizontal side clearance cannot be regulated, and active control and adaptive regulation of system vibration cannot be achieved. Summary of the invention

[0005] The present invention provides a clearance-adjustable sliding bearing structure, a supporting rotor system and a vibration control method thereof, which solves the problems disclosed in the background technology. The sliding bearing can adjust both the top clearance and the side clearance, and realizes active control and adaptive adjustment of the journal vibration through PID control, thereby improving the operating stability of the rotor system.

[0006] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0007] A clearance adjustable sliding bearing structure comprises a bearing housing, a first bearing pad and a second bearing pad, wherein the bearing housing is divided into two oppositely arranged halves, wherein one of the halves is provided with a first displacement actuator and a second displacement actuator via a fixing mechanism, wherein the first displacement actuator and the second displacement actuator are respectively bonded to the first bearing pad; and the other half is provided with a third displacement actuator and a fourth displacement actuator via a fixing mechanism, wherein the third displacement actuator and the fourth displacement actuator are respectively bonded to the second bearing pad;

[0008] The first displacement actuator and the third displacement actuator are located in a vertical direction and are connected to a first PID controller, and the first PID controller is used to control the vertical displacement of the first bearing pad and the second bearing pad; the second displacement actuator and the fourth displacement actuator are located in a horizontal direction and are connected to a second PID controller, and the second PID controller is used to control the horizontal displacement of the first bearing pad and the second bearing pad; a journal is arranged between the first bearing pad and the second bearing pad, and the clearance between the bearing and the journal is adjusted by controlling the vertical and horizontal displacements of the first bearing pad and the second bearing pad;

[0009] The first bearing pad and the second bearing pad are provided with a first displacement sensor and a second displacement sensor. The first displacement sensor is used to monitor the vertical displacement of the first bearing pad and the second bearing pad, and send it to the first PID controller; the second displacement sensor is used to monitor the horizontal displacement of the first bearing pad and the second bearing pad, and send it to the second PID controller.

[0010] Furthermore, the fixing mechanism includes a screw, a clamp body and a pre-tightening screw; the clamp body is connected to the bearing housing via a screw; one end of the pre-tightening screw is connected to the clamp body, and the other end is connected to the first displacement actuator / third displacement actuator / second displacement actuator / fourth displacement actuator.

[0011] Furthermore, the first bearing pad and the second bearing pad are respectively provided with positioning screws; the first displacement actuator and the second displacement actuator are respectively bonded to the positioning screws of the first bearing pad; the third displacement actuator and the fourth displacement actuator are respectively bonded to the positioning screws of the second bearing pad.

[0012] Furthermore, the positioning screw is provided with a nut, and an elastic gasket is provided between the nut and the bearing housing.

[0013] A second aspect of the present invention provides a rotor support system, wherein the rotor support system is provided with a plurality of the above-mentioned clearance-adjustable sliding bearing structures.

[0014] A third aspect of the present invention provides a vibration control method for the above-mentioned supporting rotor system, comprising:

[0015] Construct a mathematical model of the rotor system under journal disturbance and obtain the dynamic parameters of the bearing pads under journal disturbance;

[0016] When the actuator is used to adjust the horizontal displacement of the bearing pad, only the horizontal disturbance of the bearing pad is considered, and the dynamic coefficient of the bearing pad during horizontal disturbance is solved;

[0017] When the actuator is used to adjust the vertical displacement of the bearing pad, only the vertical disturbance of the bearing pad is considered, and the dynamic coefficient of the bearing pad during vertical disturbance is solved;

[0018] Calculate the optimal control parameters of the PID controller based on the dynamic coefficients of the bearing pad during horizontal and vertical disturbances;

[0019] The parameters of the PID controller are set according to the optimal control parameters. The PID controller controls the vertical and horizontal displacements of the first bearing pad and the second bearing pad through the displacement actuator to adjust the clearance with the journal.

[0020] Furthermore, a mathematical model of the rotor system under the journal disturbance is constructed, and the method for obtaining the dynamic parameters of the bearing pad under the journal disturbance is as follows:

[0021] The oil film thickness of the first bearing pad is:

[0022] (1);

[0023] The oil film thickness of the second bearing pad is:

[0024] (2);

[0025] Where c is the radial clearance of the bearing, e is the eccentricity of the journal geometric center relative to the bearing geometric center, θ is the offset angle of the journal, is the circumferential coordinate of any point on the bearing pad, δ c and Λ c are the horizontal and vertical offset distances of the center of curvature of the bearing pad relative to the geometric center of the bearing, respectively. The bearing side clearance is c-δ c , the top gap is c-Λ c ,u c v is the horizontal movement distance of the bearing pad driven by the piezoelectric actuator in the horizontal direction of the bearing pad, c The vertical movement distance of the bearing pad driven by the piezoelectric actuator in the vertical direction of the bearing pad;

[0026] Eccentricity , , non-dimensionalize formulas (1) and (2);

[0027] The dimensionless oil film thickness of the first bearing pad is:

[0028] (3);

[0029] The dimensionless oil film thickness of the second bearing pad is:

[0030] (4);

[0031] make , substitute formula (3) and formula (4) into the dimensionless static Reynolds equation (5) to obtain the static oil film pressure distribution P of the two bearing pads at a specific speed and load without active control. 01 , P 02 and oil film thickness distribution H 01 , H 02 ;

[0032] (5);

[0033] Where d and l are the bearing diameter and width respectively. is the axial coordinate of the bearing, P and H are the dimensionless oil film pressure and thickness, respectively;

[0034] Under the perturbation assumption, the static equilibrium position of the journal is recorded as (ε0, θ0), and the periodic small perturbations of the journal around the static equilibrium point in the dynamic state are recorded as E and θ. The journal position at any time is expressed as:

[0035] (6);

[0036] For each bearing pad, the dynamic pressure and oil film thickness under journal disturbance are expressed as:

[0037] (7);

[0038] The static oil film thickness of the first bearing pad is:

[0039] (8);

[0040] The static oil film thickness of the second bearing pad is:

[0041] (9);

[0042] The dynamic oil film thickness of the bearing pad is:

[0043] (10);

[0044] Substituting equation (7) into the dimensionless dynamic Reynolds equation:

[0045] (11);

[0046] Get the pressure P d The Reynolds equation is used to iteratively solve the dynamic coefficients of the bearing pad when the journal is disturbed. , the dynamic coefficient of the entire bearing is obtained by numerical superposition .

[0047] Furthermore, when the actuator is used to adjust the horizontal displacement of the bearing pad, only the disturbance of the bearing pad in the horizontal direction is considered. The method for solving the dynamic coefficient of the bearing pad during horizontal disturbance is:

[0048] make ;

[0049] (12);

[0050] Then we have: , ;

[0051] Substituting equation (12) into the dimensionless dynamic Reynolds equation (11), we obtain u The Reynolds equation is solved iteratively to obtain the dynamic coefficients of the bearing pad when it is horizontally disturbed ; Then the dynamic coefficient of the first bearing pad in bearing a is expressed as: , the dynamic coefficient of the second bearing pad is expressed as: ; Then the dynamic coefficient of the first bearing pad in bearing b is expressed as: , the dynamic coefficient of the second bearing pad is expressed as: .

[0052] Furthermore, when the actuator is used to adjust the vertical displacement of the bearing pad, only the disturbance of the bearing pad in the vertical direction is considered. The method for solving the dynamic coefficient of the bearing pad during the vertical disturbance is:

[0053] make: ;

[0054] (13);

[0055] Then we have: , ;

[0056] Substituting equation (13) into the dimensionless dynamic Reynolds equation (11), we obtain v The Reynolds equation is solved iteratively to obtain the dynamic coefficients of the bearing pad when it is vertically disturbed ; Then the dynamic coefficient of the first bearing pad in bearing a is expressed as: , the dynamic coefficient of the second bearing pad is expressed as: ; Then the dynamic coefficient of the first bearing pad in bearing b is expressed as: , the dynamic coefficient of the second bearing pad is expressed as: .

[0057] Furthermore, the method for calculating the optimal control parameters of the PID controller according to the dynamic coefficients of the bearing pad during horizontal disturbance and vertical disturbance is:

[0058] The horizontal and vertical displacement vectors of the first bearing pad in bearing a are s a1u and a1v , the horizontal and vertical displacement vectors of the second bearing pad in bearing a are s a2u and a2v , the horizontal and vertical displacement vectors of the first bearing pad in bearing b are s b1u and b1v , the horizontal and vertical displacement vectors of the second bearing pad in bearing b are s b2u and b2v , then the displacement vector of the system active control is s=[ sa1u ,s a1v ,s a2u ,s a2v ,s b1u ,s b1v ,s b2u ,s b2v ]; the optimal control parameter is calculated by using the dynamic coefficient of the first bearing pad, and the displacement vector of the active control of the system becomes s=[s a1u ,s a1v ,s b1u ,s b1v ], the displacement is converted into voltage according to the voltage-displacement equation of the displacement actuator, and the voltage vector corresponding to the displacement actuator is obtained as , d p is the piezoelectric constant, then after the displacement actuator is used for active control, the forced vibration equation of the rotor system is:

[0059] (14);

[0060] in, is the external load of the rotor system, , and They are the mass matrix, damping matrix and stiffness matrix of the rotor system, and the dynamic coefficient of the bearing when the journal is disturbed. Directly assembled to and The corresponding position of the rotor; q is the node displacement vector after the rotor is discretized. When the rotor is discretized into n nodes, q is a 4n×1 column vector. , and All are 4n×4n matrices; , are the control force stiffness and damping coefficient matrices respectively, then:

[0061] , ;

[0062] The free vibration equation of the system under optimal control conditions is:

[0063] (15);

[0064] In actual control, the integral term of the PID controller is not considered, and proportional differential control is adopted. , then the state equation of the rotor system is: (16);

[0065] Where: , , ;

[0066] Under the condition that the system can be controlled, the linear quadratic performance index of optimal control is introduced:

[0067] (17);

[0068] in, and are weight matrices used for state variables and control vectors, respectively, and can be symmetric or diagonal matrices; when the control variable When there is no constraint, the superscript "T" is the transpose of the matrix; Formula (17) is the optimal control solution of Formula (15) when J is minimized;

[0069] Assume that the optimal feedback that minimizes the optimal performance index J is for:

[0070] (18);

[0071] In the formula, the optimal feedback matrix is , where P is a positive definite constant matrix, which is the solution of the Riccati matrix algebraic equation in formula (19):

[0072] (19);

[0073] is the weight matrix and Corresponding to the optimal feedback control, different weighting matrices will result in different optimal feedback controls; the optimal feedback matrix is:

[0074] (20);

[0075] The optimal feedback control matrix is ​​obtained On this basis, the coupling terms are not considered, and only the diagonal elements are used as the basis for selecting PID control parameters; in the optimal control matrix, only the diagonal elements related to the displacement of bearing a and bearing b are taken, and the remaining elements are set to zero, then:

[0076] (twenty one);

[0077] After adding optimal feedback control, the forced vibration equation of the rotor system is:

[0078] ;

[0079] The proportional and differential constants obtained by applying formula (21) are used to set the parameters of the PID controller.

[0080] The beneficial effects achieved by the present invention are:

[0081] 1. The present invention installs piezoelectric ceramic micro-displacement actuators in the horizontal and vertical directions on the two bearing pads of the offset-elliptical sliding bearing, respectively, so as to achieve equal displacement adjustment of the top clearance or side clearance of the two bearing pads of the bearing, thereby improving the damping and running stability of the bearing;

[0082] 2. The present invention adopts a piezoelectric micro-displacement actuator and a PID feedback controller to adjust the top clearance and side clearance of the bearing, which can achieve rapid response and high-precision displacement control and meet the requirements of active real-time control of rotor system vibration.

[0083] 3. Compared with the existing adjustable top clearance structure, the present invention has no mechanical transmission mechanism, can realize the real-time adjustment of the top clearance or the side clearance at the same time, and has a compact structure and is easy to implement. BRIEF DESCRIPTION OF THE DRAWINGS

[0084] Figure 1 It is a structural schematic diagram of the sliding bearing of the present invention;

[0085] Figure 2 for Figure 1 AA section view;

[0086] Figure 3 for Figure 1 A partial enlarged view of

[0087] Figure 4 It is a schematic diagram of PID feedback control of the displacement sensor and the displacement actuator in the present invention;

[0088] Figure 5 Schematic diagram of the rotor system of the present invention. DETAILED DESCRIPTION

[0089] The present invention will be further described below in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and cannot be used to limit the protection scope of the present invention.

[0090] Embodiment 1, as Figure 1 and Figure 2 As shown, this embodiment provides a clearance-adjustable sliding bearing structure, comprising a bearing housing 12, a first bearing pad 1 and a second bearing pad 2, wherein the bearing housing 12 is divided into two relatively arranged halves, wherein one half is provided with a first displacement actuator 3 and a second displacement actuator 5 through a fixing mechanism, wherein the first displacement actuator 3 and the second displacement actuator 5 are respectively bonded to the first bearing pad 1; the other half is provided with a third displacement actuator 4 and a fourth displacement actuator 6 through a fixing mechanism, wherein the third displacement actuator 4 and the fourth displacement actuator 6 are respectively bonded to the second bearing pad 2; the displacement actuator preferably adopts a piezoelectric ceramic micro displacement actuator;

[0091] The first displacement actuator 3 and the third displacement actuator 4 are located in the vertical direction and are connected to the first PID controller, and the first PID controller is used to control the vertical displacement of the first bearing pad 1 and the second bearing pad 2 respectively through the first displacement actuator 3 and the third displacement actuator 4; the second displacement actuator 5 and the fourth displacement actuator 6 are located in the horizontal direction and are connected to the second PID controller, and the second PID controller is used to control the horizontal displacement of the first bearing pad 1 and the second bearing pad 2 respectively through the second displacement actuator 5 and the fourth displacement actuator 6; a journal 9 is arranged between the first bearing pad 1 and the second bearing pad 2, and the clearance between the bearing and the journal 9 is adjusted by controlling the vertical and horizontal displacements of the first bearing pad 1 and the second bearing pad 2;

[0092] The fixing mechanism includes a screw 10, a clamp body 13 and a pre-tightening screw 15; the clamp body 13 is connected to the bearing housing 12 through the screw 10; one end of the pre-tightening screw 15 is connected to the clamp body 13, and the other end is connected to the first displacement actuator 3 / the third displacement actuator 4 / the second displacement actuator 5 / the fourth displacement actuator 6.

[0093] The first bearing pad 1 and the second bearing pad 2 are respectively provided with positioning screws 14; the first displacement actuator 3 and the second displacement actuator 5 are respectively bonded to the positioning screws 14 of the first bearing pad 1; the third displacement actuator 4 and the fourth displacement actuator 6 are respectively bonded to the positioning screws 14 of the second bearing pad 2.

[0094] like Figure 3As shown, the positioning screw 14 is provided with a nut, and an elastic gasket 11 is provided between the nut and the bearing housing 12. When the piezoelectric ceramic micro-displacement actuator is extended under the action of voltage, the elastic gasket 11 is compressed, thereby driving the corresponding bearing pad to move slightly in the horizontal or vertical direction through the positioning screw 14, thereby adjusting the side clearance or top clearance of the bearing.

[0095] like Figure 4 As shown, the first bearing pad 1 and the second bearing pad 2 are provided with a first displacement sensor 7 and a second displacement sensor 8. The first displacement sensor 7 is used to monitor the vertical displacement of the first bearing pad 1 and the second bearing pad 2 and send it to the first PID controller; the second displacement sensor 8 is used to monitor the horizontal displacement of the first bearing pad 1 and the second bearing pad 2 and send it to the second PID controller. The first displacement sensor 7 and the second displacement sensor 8 are preferably eddy current displacement sensors, forming a feedback control of the displacement sensor-PID controller-displacement actuator, thereby realizing active adjustment of the side clearance or top clearance of the misaligned-elliptical sliding bearing.

[0096] Embodiment 2: This embodiment provides a rotor support system, which is provided with a plurality of bearings described in Embodiment 1, such as Figure 5 As shown, two bearings are preferably provided, bearing a and bearing b;

[0097] The supporting rotor system first establishes the dynamic model of this misaligned-elliptical bearing supporting rotor system containing a PID controller and a piezoelectric ceramic micro-displacement actuator, and then applies the optimal control theory to determine the optimal values ​​of the proportional, differential, and integral parameters of the PID control system when the rotor vibration displacement is controlled within a specific range, and determines the required actuator structure and parameters. The PID controller parameters are set in advance based on the optimal parameters of the PID controller obtained by theoretical analysis. The vibration displacement signal measured by the eddy current displacement sensor is input into the PID feedback controller and then processed by its proportional, differential, and integral parameters to output the same voltage to the two piezoelectric ceramic micro-displacement actuators in the vertical direction. The piezoelectric ceramic micro-displacement actuator will produce a corresponding elongation due to the inverse piezoelectric effect of the piezoelectric ceramic material, causing the elastic gaskets 11 on the two bearing pads to be compressed accordingly. Therefore, the positioning screws 14 on the two bearing pads will respectively drive the corresponding bearing pads to have equal displacements in the vertical direction, thereby improving the vibration displacement signal. The gap between the journal and the bearing pad in the vertical direction is changed to achieve adjustable top clearance of the bearing; similarly, the vibration displacement signal measured by the eddy current displacement sensor is input into the PID feedback controller and processed by its proportional, differential and integral parameters to output the same voltage to the two horizontal piezoelectric ceramic micro-displacement actuators. The inverse piezoelectric effect of the piezoelectric ceramic material will produce the same elongation to cause the elastic gasket 11 to be compressed accordingly, so that the positioning screws 14 on the two bearing pads respectively drive the corresponding bearing pads to have equal displacements in the horizontal direction, thereby changing the gap between the journal and the bearing pad in the horizontal direction and achieving adjustable side clearance of the bearing. Active control of the top clearance and side clearance of the dislocated-elliptical bearing is achieved, effectively reducing the vibration of the rotor system.

[0098] Embodiment 3: This embodiment provides a vibration control method for the supporting rotor system described in Embodiment 2, comprising the following steps:

[0099] Taking bearing a as an example, the oil film thickness corresponding to its two bearing pads can be expressed as follows:

[0100] Oil film thickness of the first bearing pad 1:

[0101] (1);

[0102] Oil film thickness of the second bearing pad 2:

[0103] (2);

[0104] Where c is the radial clearance of the bearing, e is the eccentricity of the journal geometric center relative to the bearing geometric center, θ is the offset angle of the journal, is the circumferential coordinate of any point on the bearing pad, δ c and Λ care the horizontal and vertical offset distances of the center of curvature of the bearing pad relative to the geometric center of the bearing, respectively. The bearing side clearance is c-δ c , the top gap is c-Λ c ,u c v is the horizontal movement distance of the bearing pad driven by the piezoelectric actuator in the horizontal direction of the bearing pad, c It is the vertical movement distance of the bearing pad driven by the piezoelectric actuator in the vertical direction of the bearing pad.

[0105] Eccentricity , , non-dimensionalizing formulas (1) and (2), the corresponding dimensionless oil film thickness can be obtained as:

[0106] (3);

[0107] (4);

[0108] make , the dimensionless oil film thickness formulas (3) and (4) of bearing pad 1 and bearing pad 2 are substituted into the dimensionless static Reynolds equation (5), and the static oil film pressure distribution P of the two bearing pads under a specific speed and load without active control can be obtained. 01 , P 02 and oil film thickness distribution H 01 , H 02 .

[0109] (5);

[0110] Where d and l are the bearing diameter and width respectively. is the axial coordinate of the bearing, P and H are the dimensionless oil film pressure and thickness, respectively.

[0111] Under the assumption of small disturbance, the static equilibrium position of the journal is recorded as (ε0, θ0), and the periodic small disturbances of the journal around the static equilibrium point in the dynamic state are recorded as E and θ. Then the journal position at any time can be expressed as:

[0112] (6);

[0113] For each bearing pad, the dynamic pressure and oil film thickness under small journal disturbance can be expressed as:

[0114] (7);

[0115] The static oil film thickness of the bearing pads are:

[0116] (8);

[0117] (9);

[0118] The dynamic oil film thickness of the bearing pads are:

[0119] (10);

[0120] Substituting equation (7) into the dimensionless dynamic Reynolds equation:

[0121] (11);

[0122] The pressure P can be obtained d The Reynolds equation can be solved iteratively to obtain the eight dynamic coefficients of the bearing pad when the journal is slightly disturbed. , through numerical superposition, the 8 dynamic coefficients of the entire bearing can be obtained The method for calculating the oil film pressure is a prior art and will not be described in detail.

[0123] When the piezoelectric actuator is used to adjust the horizontal displacement of the bearing pad, only the small disturbance of the bearing pad in the horizontal direction is considered, and the following is made:

[0124] ;

[0125] (12);

[0126] Then we have: , .

[0127] Substituting equation (12) into the dimensionless dynamic Reynolds equation (11), we can obtain the pressure P u The Reynolds equation can be solved iteratively to obtain the four dynamic coefficients of the bearing pad when the horizontal small disturbance occurs. Then the four coefficients of the first bearing pad 1 in bearing a are expressed as: , the four coefficients of the second bearing pad 2 are expressed as: ; Then the four coefficients of the first bearing pad 1 in bearing b are expressed as: , the four coefficients of the second bearing pad 2 are expressed as: .

[0128] Similarly, when the piezoelectric actuator is used to adjust the vertical displacement of the bearing pad, only the small disturbance of the bearing pad in the vertical direction is considered, and:

[0129] ;

[0130] (13)

[0131] Then we have: , .

[0132] Substituting equation (13) into the dimensionless dynamic Reynolds equation (11), we can obtain the pressure P v The Reynolds equation can be solved iteratively to obtain the four dynamic coefficients of the bearing pad when the vertical small disturbance occurs. Then the four coefficients of the first bearing pad 1 in bearing a are expressed as: , the four coefficients of the second bearing pad 2 are expressed as: ; Then the four coefficients of the first bearing pad 1 in bearing b are expressed as: , the four coefficients of the second bearing pad 2 are expressed as: .

[0133] When bearings a and b are both Figure 1 When active control is performed in the manner shown, it is assumed that the horizontal and vertical displacement vectors of the first bearing pad 1 in the bearing a are s under the action of the piezoelectric actuator. a1u and a1v , the horizontal and vertical displacement vectors of the second bearing pad 2 in bearing a are s a2u and a2v , the horizontal and vertical displacement vectors of the first bearing pad 1 in bearing b are s b1u and b1v , the horizontal and vertical displacement vectors of the second bearing pad 2 in bearing b are s b2u and b2v , then the displacement vector of the system active control is s=[ sa1u ,s a1v ,s a2u ,s a2v ,s b1u ,s b1v ,s b2u ,s b2v ]. Since the two bearing pads of each bearing need to be under the action of the same PID controller, so that its actuator drives the two bearing pads to produce equal displacements in the horizontal or vertical direction, only the dynamic coefficient of the main load-bearing first bearing pad 1 is used to calculate the optimal control parameters. Then the displacement vector of the system active control becomes s=[s a1u ,s a1v ,s b1u ,s b1v ], according to the voltage-displacement equation of the piezoelectric actuator, the displacement is converted into voltage, and the voltage vector corresponding to the actuator is obtained as (d p is the piezoelectric constant), then after active control using the piezoelectric actuator, the forced vibration equation of the rotor system can be written as:

[0134] (14);

[0135] in, is the external load of the rotor system, , and They are the mass matrix, damping matrix and stiffness matrix of the rotor system, and the eight dynamic coefficients of the bearing when the journal is slightly disturbed. Directly assembled to and q is the node displacement vector after the rotor is discretized (when the rotor is discretized into n nodes, q is a 4n×1 column vector, , and are all 4n×4n matrices). , are the control force stiffness and damping coefficient matrices respectively. Figure 5 The rotor system shown has:

[0136] , ;

[0137] The free vibration equation of the system under optimal control conditions is:

[0138] (15);

[0139] In actual control, the integral term of the PID controller is not considered, and proportional differential control is adopted. , then the state equation of the rotor system is:

[0140] (16);

[0141] Where:

[0142] , , .

[0143] Under the condition that the system can be controlled, the linear quadratic performance index of optimal control is introduced:

[0144] (17);

[0145] in, and are weight matrices used for state variables and control vectors, respectively, and are generally symmetric or diagonal matrices. When there are no constraints, the superscript "T" is the transpose of the matrix. Formula (17) is the optimal control solution of Formula (15) when J is minimized.

[0146] Assume that the optimal feedback that minimizes the optimal performance index J is for:

[0147] (18);

[0148] In the formula, the optimal feedback matrix is , where P is a positive constant matrix, which is the solution of the Riccati matrix algebraic equation in equation (19):

[0149] (19);

[0150] is the weight matrix and Corresponding to the optimal feedback control, different weighting matrices will result in different optimal feedback controls. The optimal feedback matrix can be written as:

[0151] (20);

[0152] In engineering practice, it is very difficult to achieve the optimal feedback matrix. Usually, the optimal feedback control matrix is ​​obtained. On this basis, the coupling terms are not considered, and only the diagonal elements are used as the basis for selecting PID control parameters. Therefore, in the optimal control matrix, only the diagonal elements related to the displacement of bearing a and bearing b are taken, and the remaining elements are set to zero, then:

[0153] (twenty one);

[0154] After adding optimal feedback control, the forced vibration equation of the rotor system is:

[0155]

[0156] By using the proportional and differential constants obtained from formula (21) to set the parameters of the PID controller, feedback control of the sensor-PID controller-actuator can be realized, thereby actively adjusting the side clearance or top clearance of the misaligned-elliptical bearing and ultimately suppressing the rotor vibration.

[0157] It should be noted that in the field of sliding bearings, small disturbances in the journal will cause the following effects:

[0158] Oil film thickness: Under stable working conditions, the thickness of the oil film is generally between tens of microns and hundreds of microns. When subject to small disturbances, the fluctuation range of the oil film thickness may be around ±5μm to ±20μm.

[0159] Friction coefficient: Usually between 0.001 and 0.05. Small disturbances may cause the friction coefficient to fluctuate within this range by around 0.0005 to 0.005.

[0160] Temperature: When the sliding bearing is working normally, the temperature is generally around 50℃ to 100℃. Small disturbances may cause the temperature to rise or fall by 5℃ to 15℃.

[0161] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

[0162] A computer-readable storage medium storing one or more programs including instructions that, when executed by a computing device, cause the computing device to perform a vibration control method for a supported rotor system.

[0163] A computing device includes one or more processors, one or more memories, and one or more programs, wherein the one or more programs are stored in the one or more memories and configured to be executed by the one or more processors, and the one or more programs include instructions for executing a vibration control method for a supported rotor system.

[0164] It will be appreciated by those skilled in the art that embodiments of the present invention may be provided as methods, systems, or computer program products. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Furthermore, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0165] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0166] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0167] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0168] The above are merely embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention are included in the scope of the claims of the present invention to be approved.

Claims

1. A clearance-adjustable sliding bearing structure, characterized in that: The invention comprises a bearing housing, a first bearing pad and a second bearing pad, wherein the bearing housing is divided into two oppositely arranged halves, wherein one of the halves is provided with a first displacement actuator and a second displacement actuator through a fixing mechanism, wherein the first displacement actuator and the second displacement actuator are respectively bonded to the first bearing pad; and the other half is provided with a third displacement actuator and a fourth displacement actuator through a fixing mechanism, wherein the third displacement actuator and the fourth displacement actuator are respectively bonded to the second bearing pad; The first displacement actuator and the third displacement actuator are located in a vertical direction and are connected to a first PID controller, and the first PID controller is used to control the vertical displacement of the first bearing pad and the second bearing pad; the second displacement actuator and the fourth displacement actuator are located in a horizontal direction and are connected to a second PID controller, and the second PID controller is used to control the horizontal displacement of the first bearing pad and the second bearing pad; a journal is arranged between the first bearing pad and the second bearing pad, and the clearance between the bearing and the journal is adjusted by controlling the vertical and horizontal displacements of the first bearing pad and the second bearing pad; The first bearing pad and the second bearing pad are provided with a first displacement sensor and a second displacement sensor. The first displacement sensor is used to monitor the vertical displacement of the first bearing pad and the second bearing pad, and send it to the first PID controller; the second displacement sensor is used to monitor the horizontal displacement of the first bearing pad and the second bearing pad, and send it to the second PID controller.

2. The clearance-adjustable sliding bearing structure according to claim 1, characterized in that: The fixing mechanism includes a screw, a clamp body and a pre-tightening screw; the clamp body is connected to the bearing housing via a screw; one end of the pre-tightening screw is connected to the clamp body, and the other end is connected to the first displacement actuator / third displacement actuator / second displacement actuator / fourth displacement actuator.

3. The clearance-adjustable sliding bearing structure according to claim 1, characterized in that: The first bearing pad and the second bearing pad are respectively provided with positioning screws; the first displacement actuator and the second displacement actuator are respectively bonded to the positioning screws of the first bearing pad; the third displacement actuator and the fourth displacement actuator are respectively bonded to the positioning screws of the second bearing pad.

4. The clearance-adjustable sliding bearing structure according to claim 3, characterized in that: The positioning screw is provided with a nut, and an elastic gasket is provided between the nut and the bearing housing.

5. A rotor support system, characterized in that: The rotor supporting system is provided with a plurality of clearance-adjustable sliding bearing structures as described in any one of claims 1-4.

6. The vibration control method of the supporting rotor system according to claim 5, characterized in that: include: Construct a mathematical model of the rotor system under journal disturbance and obtain the dynamic parameters of the bearing pads under journal disturbance; When the actuator is used to adjust the horizontal displacement of the bearing pad, only the horizontal disturbance of the bearing pad is considered, and the dynamic coefficient of the bearing pad during horizontal disturbance is solved; When the actuator is used to adjust the vertical displacement of the bearing pad, only the vertical disturbance of the bearing pad is considered, and the dynamic coefficient of the bearing pad during vertical disturbance is solved; Calculate the optimal control parameters of the PID controller based on the dynamic coefficients of the bearing pad during horizontal and vertical disturbances; The parameters of the PID controller are set according to the optimal control parameters. The PID controller controls the vertical and horizontal displacements of the first bearing pad and the second bearing pad through the displacement actuator to adjust the clearance with the journal.

7. The method for controlling vibration of a supporting rotor system according to claim 6, characterized in that: The mathematical model of the rotor system under the journal disturbance is constructed, and the method for obtaining the dynamic parameters of the bearing pad under the journal disturbance is as follows: The oil film thickness of the first bearing pad is: （1）； The oil film thickness of the second bearing pad is: （2）； Where c is the radial clearance of the bearing, e is the eccentricity of the journal geometric center relative to the bearing geometric center, θ is the offset angle of the journal, is the circumferential coordinate of any point on the bearing pad, δ c and Λ c are the horizontal and vertical offset distances of the center of curvature of the bearing pad relative to the geometric center of the bearing, respectively. The bearing side clearance is c-δ c , the top gap is c-Λ c ,u c v is the horizontal movement distance of the bearing pad driven by the piezoelectric actuator in the horizontal direction of the bearing pad, c The vertical movement distance of the bearing pad driven by the piezoelectric actuator in the vertical direction of the bearing pad; Eccentricity , , non-dimensionalize formulas (1) and (2); The dimensionless oil film thickness of the first bearing pad is: (3)； The dimensionless oil film thickness of the second bearing pad is: (4)； make , substitute formula (3) and formula (4) into the dimensionless static Reynolds equation (5) to obtain the static oil film pressure distribution P of the two bearing pads at a specific speed and load without active control. 01 , P 02 and oil film thickness distribution H 01 , H 02 ; （5）； Where d and l are the bearing diameter and width respectively. is the axial coordinate of the bearing, P and H are the dimensionless oil film pressure and thickness, respectively; Under the perturbation assumption, the static equilibrium position of the journal is recorded as (ε0, θ0), and the periodic small perturbations of the journal around the static equilibrium point in the dynamic state are recorded as E and θ. The journal position at any time is expressed as: （6）； For each bearing pad, the dynamic pressure and oil film thickness under journal disturbance are expressed as: （7）； The static oil film thickness of the first bearing pad is: （8）； The static oil film thickness of the second bearing pad is: （9）； The dynamic oil film thickness of the bearing pad is: （10）； Substituting equation (7) into the dimensionless dynamic Reynolds equation: （11）； Get the pressure P d The Reynolds equation is used to iteratively solve the dynamic coefficients of the bearing pad when the journal is disturbed. , the dynamic coefficient of the entire bearing is obtained by numerical superposition .

8. The vibration control method of the supporting rotor system according to claim 7, characterized in that: When the actuator is used to adjust the horizontal displacement of the bearing pad, only the disturbance of the bearing pad in the horizontal direction is considered. The method for solving the dynamic coefficient of the bearing pad during horizontal disturbance is: make ; （12）； Then we have: , ; Substituting equation (12) into the dimensionless dynamic Reynolds equation (11), we obtain u The Reynolds equation is solved iteratively to obtain the dynamic coefficients of the bearing pad when it is horizontally disturbed ; Then the dynamic coefficient of the first bearing pad in bearing a is expressed as: , the dynamic coefficient of the second bearing pad is expressed as: ; Then the dynamic coefficient of the first bearing pad in bearing b is expressed as: , the dynamic coefficient of the second bearing pad is expressed as: .

9. The vibration control method of the supporting rotor system according to claim 8, characterized in that: When the actuator is used to adjust the vertical displacement of the bearing pad, only the vertical disturbance of the bearing pad is considered. The method for solving the dynamic coefficient of the bearing pad during vertical disturbance is: make: ; （13）； Then we have: , ; Substituting equation (13) into the dimensionless dynamic Reynolds equation (11), we obtain v The Reynolds equation is solved iteratively to obtain the dynamic coefficients of the bearing pad when it is vertically disturbed ; Then the dynamic coefficient of the first bearing pad in bearing a is expressed as: , the dynamic coefficient of the second bearing pad is expressed as: ; Then the dynamic coefficient of the first bearing pad in bearing b is expressed as: , the dynamic coefficient of the second bearing pad is expressed as: .

10. The vibration control method of the supporting rotor system according to claim 9, characterized in that: The method for calculating the optimal control parameters of the PID controller based on the dynamic coefficients of the bearing pad during horizontal and vertical disturbances is: The horizontal and vertical displacement vectors of the first bearing pad in bearing a are s a1u and a1v , the horizontal and vertical displacement vectors of the second bearing pad in bearing a are s a2u and a2v , the horizontal and vertical displacement vectors of the first bearing pad in bearing b are s b1u and b1v , the horizontal and vertical displacement vectors of the second bearing pad in bearing b are s b2u and b2v , then the displacement vector of the system active control is s=[ sa1u ,s a1v ,s a2u ,s a2v ,s b1u ,s b1v ,s b2u ,s b2v ]; the optimal control parameter is calculated by using the dynamic coefficient of the first bearing pad, and the displacement vector of the active control of the system becomes s=[s a1u ,s a1v ,s b1u ,s b1v ], the displacement is converted into voltage according to the voltage-displacement equation of the displacement actuator, and the voltage vector corresponding to the displacement actuator is obtained as , d p is the piezoelectric constant, then after the displacement actuator is used for active control, the forced vibration equation of the rotor system is: （14）； in, is the external load of the rotor system, , and They are the mass matrix, damping matrix and stiffness matrix of the rotor system, and the dynamic coefficient of the bearing when the journal is disturbed. Directly assembled to and The corresponding position of the rotor; q is the node displacement vector after the rotor is discretized. When the rotor is discretized into n nodes, q is a 4n×1 column vector. , and All are 4n×4n matrices; , are the control force stiffness and damping coefficient matrices respectively, then: ， ； The free vibration equation of the supporting rotor system under the optimal control condition is: （15）； In actual control, the integral term of the PID controller is not considered, and proportional differential control is adopted. , then the state equation of the rotor system is: (16); Where: , , ; Under the condition that the system can be controlled, the linear quadratic performance index of optimal control is introduced: （17）； in, and are weight matrices used for state variables and control vectors, respectively, and can be symmetric or diagonal matrices; when the control variable When there is no constraint, the superscript "T" is the transpose of the matrix; Formula (17) is the optimal control solution of Formula (15) when J is minimized; Assume that the optimal feedback that minimizes the optimal performance index J is for: （18）； In the formula, the optimal feedback matrix is , where P is a positive definite constant matrix, which is the solution of the Riccati matrix algebraic equation in formula (19): （19）； is the weight matrix and Corresponding to the optimal feedback control, different weighting matrices will result in different optimal feedback controls; the optimal feedback matrix is: （20）； The optimal feedback control matrix is ​​obtained On this basis, the coupling terms are not considered, and only the diagonal elements are used as the basis for selecting PID control parameters; in the optimal control matrix, only the diagonal elements related to the displacement of bearing a and bearing b are taken, and the remaining elements are set to zero, then: （21）； After adding optimal feedback control, the forced vibration equation of the rotor system is: ； The proportional and differential constants obtained by applying formula (21) are used to set the parameters of the PID controller.

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