A kind of gap adjustable sliding bearing structure, support rotor system and its vibration control method

Abstract

This invention discloses an adjustable clearance sliding bearing structure, a rotor support system, and a vibration control method thereof. The bearing structure includes two bearing pads and a displacement actuator. The two bearing pads have identical structures and are symmetrically distributed vertically. The displacement actuator enables the bearing pads to move slightly in the vertical and horizontal directions, thereby adjusting the side clearance and top clearance of the bearing. The displacement actuator is connected to the output of a PID controller, and the input of the PID controller is connected to a displacement sensor. The rotor system includes feedback control of the displacement sensor, PID controller, and displacement actuator, thereby achieving active adjustment of the side clearance or top clearance of the misaligned-elliptical bearing, ultimately suppressing rotor vibration.

Description

Technical Field

[0001] This invention relates to a sliding bearing structure with adjustable clearance, a rotor support system, and a vibration control method thereof, belonging to the field of sliding bearings. Background Technology

[0002] Offset-elliptical radial sliding bearings are used in large rotating machinery such as steam turbines and heavy-duty gas turbines due to their high load-bearing capacity and good stability. They generally consist of two bearing pads, upper and lower. The clearance between the journal and the bearing pad can be divided into top clearance and side clearance. Top clearance is the vertical clearance between the journal and the bearing pad, while side clearance is the horizontal clearance. Radial clearance has a significant impact on the vibration characteristics of the mechanical system. The lubrication performance of sliding bearings varies significantly with different radial clearances, and the radial clearance of traditional sliding bearings cannot be adjusted in real time. In complex service environments, the operating state of the sliding bearing-rotor system is significantly affected by changes in operating parameters such as speed and load.

[0003] To adapt to time-varying service conditions and improve the operational stability of rotating machinery, many researchers have proposed adjustable clearance sliding bearings. These bearings can improve lubrication characteristics and further enhance rotor system stability by altering the clearance based on the journal vibration state using a mechanical transmission structure. However, most research focuses on improving bearing vibration characteristics through clearance adjustment, with little exploration of the impact of bearing side clearance on lubrication characteristics. Therefore, this invention proposes a misaligned-elliptical radial sliding bearing with adjustable clearance and side clearance. This sliding bearing, with both adjustable clearance and side clearance, significantly outperforms sliding bearings that only have adjustable clearance in improving rotor system operation.

[0004] An intelligent bearing support device with adjustable geometry (application number: 201710289838.0) discloses a bearing with adjustable top clearance only. By changing the top clearance, the oil film force acting on the journal is altered, thereby controlling the bearing performance. However, this adjustable mechanism has certain limitations; it can only adjust the top clearance in the vertical direction, while the horizontal side clearance cannot be adjusted, thus failing to achieve active control and adaptive adjustment of system vibration. Summary of the Invention

[0005] This invention provides a sliding bearing structure with adjustable clearance, a rotor support system, and a vibration control method thereof, solving the problems disclosed in the background art. The sliding bearing can adjust both the top clearance and the side clearance, and through PID control, it achieves active control and adaptive adjustment of journal vibration, improving the operational stability of the rotor system.

[0006] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0007] An adjustable clearance sliding bearing structure includes a bearing housing, a first bearing pad, and a second bearing pad. The bearing housing is divided into two opposing halves. One half is provided with a first displacement actuator and a second displacement actuator via a fixing mechanism. The first displacement actuator and the second displacement actuator are respectively bonded to the first bearing pad. The other half is provided with a third displacement actuator and a fourth displacement actuator via a fixing mechanism. The third displacement actuator and the fourth displacement actuator are respectively bonded to the second bearing pad.

[0008] The first and third displacement actuators are located in the vertical direction and are connected to a first PID controller. The first PID controller is used to control the vertical displacement of the first and second bearing pads. The second and fourth displacement actuators are located in the horizontal direction and are connected to a second PID controller. The second PID controller is used to control the horizontal displacement of the first and second bearing pads. A journal is provided between the first and second bearing pads. The clearance between the bearing and the journal is adjusted by controlling the vertical and horizontal displacements of the first and second bearing pads.

[0009] The first bearing pad and the second bearing pad are equipped 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 clamping body, and a preload screw; the clamping body is connected to the bearing housing via the screw; one end of the preload screw is connected to the clamping 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 washer 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 adjustable clearance sliding bearing structures.

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

[0015] A mathematical model of the rotor system under journal disturbance is constructed to obtain the dynamic parameters of the bearing pads under journal disturbance.

[0016] When using an actuator 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 under horizontal disturbance is solved.

[0017] When using an actuator 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 under vertical disturbance is solved.

[0018] The optimal control parameters of the PID controller are calculated based on the dynamic coefficients of the bearing pads under horizontal and vertical disturbances.

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

[0020] Furthermore, the method for constructing a mathematical model of the rotor system under journal disturbance and obtaining the dynamic parameters of the bearing pads during 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 bearing's radial clearance, e is the eccentricity of the journal's geometric center relative to the bearing's geometric center, and θ is the journal's offset angle. Let δ be the circumferential coordinate of any point on the bearing pad. c and Λ c Let c and δ be the offset distances of the bearing pad curvature center relative to the bearing geometric center in the horizontal and vertical directions, respectively. Then the bearing clearance is c-δ. c The top gap is c-Λ c u c v is the horizontal movement distance of the bearing pad caused by the piezoelectric actuator moving the bearing pad in the horizontal direction. c The vertical movement distance of the bearing pad caused by the piezoelectric actuator in the vertical direction of the bearing pad;

[0026] Let the eccentricity , , dimensionlessize 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 Substituting equations (3) and (4) into the dimensionless static Reynolds equation (5), the static oil film pressure distribution P of the two bearing pads under specific speeds and loads without active control is obtained. 01 P 02 And oil film thickness distribution H 01 H 02 ;

[0032] (5);

[0033] In the formula, d and l are the bearing diameter and width, respectively. Let P be the axial coordinate of the bearing, and let H be the dimensionless oil film pressure and thickness, respectively.

[0034] Under the perturbation assumption, let the static equilibrium position of the journal be (ε0, θ0), and let the periodic small perturbations of the journal around the static equilibrium point in the dynamic state be E and Θ. Then the journal position at any time can be expressed as:

[0035] (6);

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

[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] Obtain information about pressure P d The Reynolds equations are used to obtain the dynamic coefficients of the bearing pads under journal disturbance through iterative solution. The dynamic coefficient of the entire bearing can be obtained by superimposing the numerical values. .

[0047] Furthermore, when using an actuator to adjust the horizontal displacement of the bearing pads, considering only the horizontal disturbance of the bearing pads, the method for solving the dynamic coefficients of the bearing pads during horizontal disturbance is as follows:

[0048] make ;

[0049] (12);

[0050] Then we have: , ;

[0051] Substituting equation (12) into the dimensionless dynamic Reynolds equation (11), we obtain the relationship between pressure P and pressure P. u The Reynolds equations are used to obtain the dynamic coefficients of the bearing pads under horizontal disturbance through iterative solution. 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: 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 using an actuator to adjust the vertical displacement of the bearing pad, considering only the vertical disturbance of the bearing pad, the method for solving the dynamic coefficient of the bearing pad under vertical disturbance is as follows:

[0053] make: ;

[0054] (13);

[0055] Then we have: , ;

[0056] Substituting equation (13) into the dimensionless dynamic Reynolds equation (11), we obtain the following about pressure P. v The Reynolds equations are used to obtain the dynamic coefficients of the bearing pads under vertical disturbance through iterative solution. 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: 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 based on the dynamic coefficients of the bearing pads under horizontal and vertical disturbances is as follows:

[0058] The horizontal and vertical displacement vectors of the first bearing pad in bearing a are s a1u and s a1v The horizontal and vertical displacement vectors of the second bearing pad in bearing a are s. a2u and s a2v The horizontal and vertical displacement vectors of the first bearing pad in bearing b are s. b1u and s b1v The horizontal and vertical displacement vectors of the second bearing pad in bearing b are s b2u and s b2v Then the displacement vector of the actively controlled system is s=[ sa1u s a1v s a2u s a2v s b1u s b1v s b2u s b2v Using the dynamic coefficient of the first bearing pad to calculate the optimal control parameters, the displacement vector of the actively controlled system becomes s=[s a1u s a1v s b1u s b1v Based on the voltage-displacement equation of the displacement actuator, the displacement is converted into voltage, and the voltage vector corresponding to the displacement actuator is obtained. d p If is the piezoelectric constant, then after active control using a displacement actuator, the forced vibration equation of the rotor system is:

[0059] (14);

[0060] in, For the external load of the rotor system, , and These represent the mass matrix, damping matrix, and stiffness matrix of the rotor system, respectively, and the dynamic coefficient of the bearing during journal disturbance. Direct assembly and The corresponding position; q is the nodal 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; , Let the control force stiffness and damping coefficient matrices be respectively, then we have:

[0061] , ;

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

[0063] (15);

[0064] In practical control, the integral term of the PID controller is not considered; proportional-derivative control is used, and the integral term is taken as... The state equation of the rotor system is: (16);

[0065] In the formula: , , ;

[0066] Under controllable system conditions, a linear quadratic performance index for optimal control is introduced:

[0067] (17);

[0068] in, and These are the weighting matrices used for the state variables and control vectors, respectively, and can be either symmetric or diagonal matrices; when the control variables... 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;

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

[0070] (18);

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

[0072] (19);

[0073] It is a weighted matrix and The corresponding optimal feedback control will yield different optimal feedback control depending on the weighting matrix; the optimal feedback matrix is:

[0074] (20);

[0075] The optimal feedback control matrix is ​​obtained. Based on this, disregarding coupling terms, only diagonal elements are used as the basis for selecting PID control parameters; in the optimal control matrix, only the diagonal elements related to the displacements of bearings a and b are taken, and the remaining elements are set to zero, then:

[0076] (twenty one);

[0077] After incorporating 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 this invention are as follows:

[0081] 1. The present invention installs piezoelectric ceramic micro-displacement actuators in the horizontal and vertical directions on the two bearing pads of the misaligned-elliptical sliding bearing, which can realize the equal displacement adjustment of the top clearance or side clearance of the two bearing pads, thereby improving the damping and running stability of the bearing.

[0082] 2. This invention uses a piezoelectric micro-displacement actuator and a PID feedback controller to adjust the top and side clearances of the bearing, which can achieve fast response and high-precision displacement control, meeting the requirements of active real-time control of rotor system vibration.

[0083] 3. Compared with existing adjustable top clearance structures, this invention has no mechanical transmission mechanism, can simultaneously achieve real-time adjustment of top clearance or side clearance, and has a compact structure that is easy to implement. Attached Figure Description

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

[0085] Figure 2 for Figure 1 AA-direction cross-sectional view;

[0086] Figure 3 for Figure 1 A magnified view of a portion of the image;

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

[0088] Figure 5 This is a schematic diagram of the rotor system of the present invention. Detailed Implementation

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

[0090] Example 1, such as Figure 1 and Figure 2 As shown, this embodiment provides a sliding bearing structure with adjustable clearance, including a bearing housing 12, a first bearing pad 1, and a second bearing pad 2. The bearing housing 12 is divided into two opposing halves. One half is provided with a first displacement actuator 3 and a second displacement actuator 5 via a fixing mechanism. 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 via a fixing mechanism. The third displacement actuator 4 and the fourth displacement actuator 6 are respectively bonded to the second bearing pad 2. The displacement actuator is preferably 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 a first PID controller. The first PID controller is used to control the vertical displacement of the first bearing pad 1 and the second bearing pad 2 through the first displacement actuator 3 and the third displacement actuator 4, respectively. The second displacement actuator 5 and the fourth displacement actuator 6 are located in the horizontal direction and are connected to a second PID controller. The second PID controller is used to control the horizontal displacement of the first bearing pad 1 and the second bearing pad 2 through the second displacement actuator 5 and the fourth displacement actuator 6, respectively. A journal 9 is provided between the first bearing pad 1 and the second bearing pad 2. 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 clamping body 13, and a pre-tightening screw 15; the clamping body 13 is connected to the bearing housing 12 via the screw 10; one end of the pre-tightening screw 15 is connected to the clamping 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 equipped with a nut, and an elastic washer 11 is provided between the nut and the bearing housing 12. When the piezoelectric ceramic micro-displacement actuator elongates under voltage, it will compress the elastic washer 11, thereby causing the corresponding bearing pad to move slightly in the horizontal or vertical direction through the positioning screw 14, so as to realize the adjustment of the bearing's side clearance or top clearance.

[0095] like Figure 4 As shown, the first bearing pad 1 and the second bearing pad 2 are equipped 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 the data to a 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 the data to a second PID controller. The first displacement sensor 7 and the second displacement sensor 8 are preferably eddy current displacement sensors, forming a feedback control system of displacement sensor—PID controller—displacement actuator, thereby achieving active adjustment of the side clearance or top clearance of the misaligned-elliptical sliding bearing.

[0096] Example 2: This example provides a rotor support system, which includes several bearings as described in Example 1, such as... Figure 5 As shown, two bearings are preferably provided, bearing a and bearing b;

[0097] The first step in establishing a dynamic model of the misaligned elliptical bearing-supported rotor system, including a PID controller and piezoelectric ceramic micro-displacement actuators, is to first establish a dynamic model of this system. Then, optimal control theory is applied to determine the optimal values ​​of the proportional, derivative, and integral parameters of the PID control system when controlling the rotor vibration displacement within a specific range, and to determine the required actuator structure and parameters. Based on the optimal parameters of the PID controller obtained from theoretical analysis, the PID controller parameters are pre-set. The vibration displacement signal measured by the eddy current displacement sensor is input into the PID feedback controller, and after processing by its proportional, derivative, and integral parameters, it outputs the same voltage to the two vertically oriented piezoelectric ceramic micro-displacement actuators. Due to the inverse piezoelectric effect of the piezoelectric ceramic material, the piezoelectric ceramic micro-displacement actuators will produce a corresponding elongation, causing the elastic pads 11 on the two bearing pads to compress accordingly. Therefore, the positioning screws 14 on the two bearing pads will respectively drive the corresponding bearing pads to undergo opposite displacements of equal magnitude in the vertical direction, thereby changing the... The vertical clearance between the journal and bearing pads is adjusted to achieve adjustable bearing top clearance. Similarly, the vibration displacement signal measured by the eddy current displacement sensor is input into the PID feedback controller. After processing by its proportional, derivative, and integral parameters, it outputs the same voltage to two horizontal piezoelectric ceramic micro-displacement actuators. Due to the inverse piezoelectric effect of the piezoelectric ceramic material, the same elongation is generated, causing the elastic pad 11 to compress accordingly. This causes the positioning screws 14 on the two bearing pads to drive the corresponding bearing pads to move in opposite directions with equal magnitudes in the horizontal direction, thereby changing the horizontal clearance between the journal and bearing pads and achieving adjustable bearing side clearance. This achieves active control of the top clearance and side clearance of the misaligned-elliptical bearing, effectively reducing the vibration of the rotor system.

[0098] Example 3: This example provides a vibration control method for the supported rotor system described in Example 2, including 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 bearing's radial clearance, e is the eccentricity of the journal's geometric center relative to the bearing's geometric center, and θ is the journal's offset angle. Let δ be the circumferential coordinate of any point on the bearing pad. c and Λ cLet c and δ be the offset distances of the bearing pad curvature center relative to the bearing geometric center in the horizontal and vertical directions, respectively. Then the bearing clearance is c-δ. c The top gap is c-Λ c u c v is the horizontal movement distance of the bearing pad caused by the piezoelectric actuator moving the bearing pad in the horizontal direction. c The vertical movement distance of the bearing pad is caused by the piezoelectric actuator driving the bearing pad in the vertical direction.

[0105] Let the eccentricity , By dimensionlessly transforming formulas (1) and (2), the corresponding dimensionless oil film thickness can be obtained as follows:

[0106] (3);

[0107] (4);

[0108] make Substituting the dimensionless oil film thickness formulas (3) and (4) for bearing pad 1 and bearing pad 2 into the dimensionless static Reynolds equation (5), 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] In the formula, d and l are the bearing diameter and width, respectively. Let P be the axial coordinate of the bearing, and let H be the dimensionless oil film pressure and thickness, respectively.

[0111] Under the assumption of small perturbations, let the static equilibrium position of the journal be (ε0, θ0), and let the periodic small perturbations of the journal around the static equilibrium point in the dynamic state be 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 disturbances can be expressed as:

[0114] (7);

[0115] The static oil film thicknesses of the bearing pads are as follows:

[0116] (8);

[0117] (9);

[0118] The dynamic oil film thicknesses of the bearing pads are as follows:

[0119] (10);

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

[0121] (11);

[0122] Information about pressure P can be obtained. d The Reynolds equations can be solved iteratively to obtain eight dynamic coefficients of the bearing pads under small journal disturbances. By superimposing the values, the eight dynamic coefficients of the entire bearing can be obtained. The method for calculating oil film pressure is existing technology and will not be elaborated upon here.

[0123] When using a piezoelectric actuator to adjust the horizontal displacement of the bearing pads, considering only small horizontal disturbances in the bearing pads, let:

[0124] ;

[0125] (12);

[0126] Then we have: , .

[0127] Substituting equation (12) into the dimensionless dynamic Reynolds equation (11), we can obtain the relationship between pressure P and pressure P. u The Reynolds equations can be solved iteratively to obtain the four dynamic coefficients for small horizontal disturbances in the bearing pads. Then the four coefficients of the first bearing pad 1 in bearing a are expressed as follows: The four coefficients of the second bearing pad 2 are expressed as follows: Then the four coefficients of the first bearing pad 1 in bearing b are expressed as follows: The four coefficients of the second bearing pad 2 are expressed as follows: .

[0128] Similarly, when using a piezoelectric actuator to adjust the vertical displacement of the bearing pad, considering only the small vertical disturbance of the bearing pad, let:

[0129] ;

[0130] (13)

[0131] Then we have: , .

[0132] Substituting equation (13) into the dimensionless dynamic Reynolds equation (11), we can obtain the relationship between pressure P and pressure P. v The Reynolds equations can be solved iteratively to obtain the four dynamic coefficients for small vertical disturbances in the bearing pads. Then the four coefficients of the first bearing pad 1 in bearing a are expressed as follows: The four coefficients of the second bearing pad 2 are expressed as follows: Then the four coefficients of the first bearing pad 1 in bearing b are expressed as follows: The four coefficients of the second bearing pad 2 are expressed as follows: .

[0133] When bearings a and b both adopt Figure 1 When active control is performed as shown, assuming that the horizontal and vertical displacement vectors of the first bearing pad 1 in bearing a are s under the action of the piezoelectric actuator. a1u and s a1v The horizontal and vertical displacement vectors of the second bearing pad 2 in bearing a are s. a2u and s a2v The horizontal and vertical displacement vectors of the first bearing pad 1 in bearing b are s. b1u and s b1v The horizontal and vertical displacement vectors of the second bearing pad 2 in bearing b are s b2u and s b2v Then the displacement vector of the actively controlled system 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 controlled by the same PID controller so that their actuators can drive the two bearing pads to produce opposing displacements of equal magnitude in the horizontal or vertical direction, only the dynamic coefficient of the primary bearing pad 1 is used to calculate the optimal control parameters. Therefore, the displacement vector of the actively controlled system becomes s = [s...]. a1u s a1v s b1u s b1v Based on 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 follows: (d) p (where is the piezoelectric constant), then the forced vibration equation of the rotor system after active control using a piezoelectric actuator can be written as:

[0134] (14);

[0135] in, For the external load of the rotor system, , and These represent the mass matrix, damping matrix, and stiffness matrix of the rotor system, and the eight dynamic coefficients of the bearing under small journal disturbances. Direct assembly and The corresponding position. q is the nodal displacement vector after rotor discretization (when the rotor is discretized into n nodes, q is a 4n×1 column vector). , and All are 4n×4n matrices. , These are the control force stiffness and damping coefficient matrices, respectively. For 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 practical control, the integral term of the PID controller is not considered; proportional-derivative control is used, and the integral term is taken as... The state equation of the rotor system is:

[0140] (16);

[0141] In the formula:

[0142] , , .

[0143] Under controllable system conditions, a linear quadratic performance index for optimal control is introduced:

[0144] (17);

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

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

[0147] (18);

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

[0149] (19);

[0150] It is a weighted matrix and Different optimal feedback controls will be obtained depending on the weighting matrix. The optimal feedback matrix can be written as:

[0151] (20);

[0152] In practical engineering, achieving the optimal feedback matrix is ​​very difficult; typically, the optimal feedback control matrix is ​​obtained from the calculated optimal feedback control matrix. Based on this, disregarding coupling terms, only diagonal elements are used as the basis for selecting PID control parameters. Therefore, the optimal control matrix only takes the diagonal elements related to the displacements of bearings a and b, setting the remaining elements to zero, then we have:

[0153] (twenty one);

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

[0155]

[0156] By applying the proportional and differential constants obtained by formula (21) to set the parameters of the PID controller, feedback control of sensor-PID controller-actuator can be realized, thereby realizing active adjustment of the side clearance or top clearance of the misaligned-elliptical bearing, and finally suppressing the rotor vibration.

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

[0158] Oil film thickness: Under stable operating conditions, the oil film thickness is generally between tens of micrometers and hundreds of micrometers. When subjected to small disturbances, the oil film thickness may fluctuate within a range of approximately ±5μm to ±20μm.

[0159] Coefficient of friction: It is usually between 0.001 and 0.05. Small disturbances may cause the coefficient of friction to fluctuate by about 0.0005 to 0.005 within this range.

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

[0161] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

[0162] A computer-readable storage medium storing one or more programs, the 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 performing a vibration control method for a supported rotor system.

[0164] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product embodied 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] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0166] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0167] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function 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 within the scope of the claims of the present invention pending approval.

Claims

1. A rotor support system, characterized in that: The invention includes an adjustable clearance sliding bearing structure, comprising a bearing housing, a first bearing pad, and a second bearing pad. The bearing housing is divided into two opposing halves. One half is fitted with a first displacement actuator and a second displacement actuator via a fixing mechanism, the first and second displacement actuators being respectively bonded to the first bearing pad. The other half is fitted with a third displacement actuator and a fourth displacement actuator via a fixing mechanism, the third and fourth displacement actuators being respectively bonded to the second bearing pad. The first and third displacement actuators are located in the vertical direction and are connected to a first PID controller. The first PID controller is used to control the vertical displacement of the first and second bearing pads. The second and fourth displacement actuators are located in the horizontal direction and are connected to a second PID controller. The second PID controller is used to control the horizontal displacement of the first and second bearing pads. A journal is provided between the first and second bearing pads. The clearance between the bearing and the journal is adjusted by controlling the vertical and horizontal displacements of the first and second bearing pads. The first bearing pad and the second bearing pad are equipped 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. The vibration control method for the supported rotor system includes: A mathematical model of the rotor system under journal disturbance is constructed to obtain the dynamic parameters of the bearing pads under journal disturbance. When using an actuator 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 under horizontal disturbance is solved. When using an actuator 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 under vertical disturbance is solved. The optimal control parameters of the PID controller are calculated based on the dynamic coefficients of the bearing pads under horizontal and vertical disturbances. The PID controller is set with optimal control parameters. The PID controller controls the vertical and horizontal displacement of the first and second bearing pads through the displacement actuator to adjust the clearance with the journal.

2. The rotor support system according to claim 1, characterized in that, The fixing mechanism includes screws, a clamping body, and a pre-tightening screw; the clamping body is connected to the bearing housing by screws; one end of the pre-tightening screw is connected to the clamping body, and the other end is connected to the first displacement actuator / third displacement actuator / second displacement actuator / fourth displacement actuator.

3. The rotor support system 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 rotor support system according to claim 3, characterized in that, The positioning screw is provided with a nut, and an elastic washer is provided between the nut and the bearing housing.

5. The rotor support system according to claim 1, characterized in that: The method for constructing a mathematical model of the rotor system under journal disturbance and obtaining the dynamic parameters of the bearing pads under 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 bearing's radial clearance, e is the eccentricity of the journal's geometric center relative to the bearing's geometric center, and θ is the journal's offset angle. Let δ be the circumferential coordinate of any point on the bearing pad. c and Λ c Let c and δ be the offset distances of the bearing pad curvature center relative to the bearing geometric center in the horizontal and vertical directions, respectively. Then the bearing clearance is c-δ. c The top gap is c-Λ c u c v is the horizontal movement distance of the bearing pad caused by the piezoelectric actuator moving the bearing pad in the horizontal direction. c The vertical movement distance of the bearing pad caused by the piezoelectric actuator in the vertical direction of the bearing pad; Let the eccentricity , , dimensionlessize 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 Substituting equations (3) and (4) into the dimensionless static Reynolds equation (5), the static oil film pressure distribution P of the two bearing pads under specific speeds and loads without active control is obtained. 01 P 02 And oil film thickness distribution H 01 H 02 ; （5）； In the formula, d and l are the bearing diameter and width, respectively. Let P be the axial coordinate of the bearing, and let H be the dimensionless oil film pressure and thickness, respectively. Under the perturbation assumption, let the static equilibrium position of the journal be (ε0, θ0), and let the periodic small perturbations of the journal around the static equilibrium point in the dynamic state be E and Θ. Then the journal position at any time can be expressed as: （6）； For each bearing pad, the dynamic pressure and oil film thickness under journal disturbance conditions are expressed as follows: （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）； Obtain information about pressure P d The Reynolds equations are used to obtain the dynamic coefficients of the bearing pads under journal disturbance through iterative solution. The dynamic coefficient of the entire bearing can be obtained by superimposing the numerical values. .

6. The rotor support system according to claim 5, characterized in that: When using an actuator to adjust the horizontal displacement of the bearing pads, considering only the horizontal disturbance of the bearing pads, the method for solving the dynamic coefficients of the bearing pads under horizontal disturbance is as follows: make ; （12）； Then we have: , ; Substituting equation (12) into the dimensionless dynamic Reynolds equation (11), we obtain the following about pressure P. u The Reynolds equations are used to obtain the dynamic coefficients of the bearing pads under horizontal disturbance through iterative solution. 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: 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: .

7. The rotor support system according to claim 6, characterized in that: When using an actuator to adjust the vertical displacement of the bearing pads, considering only the vertical disturbance of the bearing pads, the method for solving the dynamic coefficients of the bearing pads under vertical disturbance is as follows: make: ; （13）； Then we have: , ; Substituting equation (13) into the dimensionless dynamic Reynolds equation (11), we obtain the relationship between pressure P and pressure P. v The Reynolds equations are used to obtain the dynamic coefficients of the bearing pads under vertical disturbance through iterative solution. 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: 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: .

8. The rotor support system according to claim 7, characterized in that: The method for calculating the optimal control parameters of the PID controller based on the dynamic coefficients of the bearing pads under horizontal and vertical disturbances is as follows: The horizontal and vertical displacement vectors of the first bearing pad in bearing a are s a1u and s a1v The horizontal and vertical displacement vectors of the second bearing pad in bearing a are s. a2u and s a2v The horizontal and vertical displacement vectors of the first bearing pad in bearing b are s. b1u and s b1v The horizontal and vertical displacement vectors of the second bearing pad in bearing b are s b2u and s b2v Then the displacement vector of the actively controlled system is s=[ sa1u s a1v s a2u s a2v s b1u s b1v s b2u s b2v Using the dynamic coefficient of the first bearing pad to calculate the optimal control parameters, the displacement vector of the actively controlled system becomes s=[s a1u s a1v s b1u s b1v Based on the voltage-displacement equation of the displacement actuator, the displacement is converted into voltage, and the voltage vector corresponding to the displacement actuator is obtained. d p If is the piezoelectric constant, then after active control using a displacement actuator, the forced vibration equation of the rotor system is: （14）； in, For the external load of the rotor system, , and These represent the mass matrix, damping matrix, and stiffness matrix of the rotor system, respectively, and the dynamic coefficient of the bearing during journal disturbance. Direct assembly and The corresponding position; q is the nodal 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; , Let the control force stiffness and damping coefficient matrices be respectively, then we have: ， ； The free vibration equation of the supported rotor system under optimal control conditions is: （15）； In practical control, the integral term of the PID controller is not considered; proportional-derivative control is used, and the integral term is taken as... The state equation of the rotor system is: (16); In the formula: , , ; Under controllable system conditions, a linear quadratic performance index for optimal control is introduced: （17）； in, and These are the weighting matrices used for the state variables and control vectors, respectively, and can be either symmetric or diagonal matrices; when the control variables... 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; Assume the optimal feedback that minimizes the optimal performance index J. for: （18）； In the formula, the optimal feedback matrix is: P is a positive definite constant matrix, and is the solution to the Riccati matrix algebraic equation (19): （19）； It is a weighted matrix and The corresponding optimal feedback control will yield different optimal feedback control depending on the weighting matrix; the optimal feedback matrix is: （20）； The optimal feedback control matrix is ​​obtained. Based on this, disregarding coupling terms, only diagonal elements are used as the basis for selecting PID control parameters; in the optimal control matrix, only the diagonal elements related to the displacements of bearings a and b are taken, and the remaining elements are set to zero, then: （21）； After incorporating 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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