Automatic bearing elevation adjusting system and method based on electrostrictive material

Abstract

The invention discloses an automatic bearing elevation adjusting system and method based on an electrostrictive material, and the system is characterized in that an electrostrictive execution unit is embedded between a bearing bush and a sizing block, so that the integrity of a bearing structure is not affected in an electrostrictive adjusting process, a rotor does not need to be lifted or the bearing bush does not need to be disassembled, and the bearing elevation is adjusted. The system has the advantages of online adjustment capability, high response speed and high control precision, is matched with a voltage amplifier, realizes micron-level elevation adjustment, adapts to the deviation trend of the shafting under different thermal states or load changes, solves the vibration fault caused by unreasonable shafting elevation distribution, and effectively supports the development requirements of intelligent maintenance and remote monitoring; according to the method, the jacking oil pressure and the lubricating oil temperature serve as the judgment basis of the elevation deviation, the method adapts to dynamic changes of a unit in a cold state, a hot state and different operation working conditions, the shaft system centering precision is ensured, the problems of vibration, abrasion and the like caused by uneven elevation distribution are solved, and the stability and reliability of equipment operation are improved.

Description

Technical Field

[0001] This invention relates to the field of rotating machinery bearing control systems, and more particularly to an automatic bearing elevation adjustment system and method based on electrostrictive materials. Background Technology

[0002] As large-scale thermal power equipment, steam turbine generator sets have shaft systems supported by multiple bearings. Each bearing must be installed at a different vertical height (bearing installation elevation) to create a reasonable lift curve and ensure proper stress and deformation distribution of the rotor during operation. However, during operation, factors such as thermal expansion, uneven foundation settlement, vacuuming, and load disturbances can cause changes in the actual bearing elevations, easily leading to thermal misalignment of the shaft system. Changes in bearing elevation cause a redistribution of loads at the support points, affecting oil film formation and bearing support characteristics, potentially resulting in abnormal vibration, accelerated wear, and oil film instability. Statistics show that bearing misalignment is a significant cause of vibration failures in rotating machinery; therefore, elevation control has become a crucial technology in the installation, inspection, and operation of generator sets.

[0003] Typically, the common practice for adjusting bearing height during equipment installation or maintenance is to add or remove shims to precisely control the vertical height of each bearing to achieve the design alignment requirements. While this method is accurate, each adjustment requires stopping the machine to remove the bearing shim assembly, which is time-consuming and labor-intensive, and cannot adapt to changes in operating conditions online. Although some high-end systems have introduced dedicated height adjustment devices to achieve online adjustment without lifting the rotor, their mechanisms are complex, costly, and have limited reliability, making practical application difficult. Summary of the Invention

[0004] Purpose of the invention: The purpose of this invention is to provide an automatic bearing elevation adjustment system based on electrostrictive materials for online, automatic, and real-time adjustment of elevation deviation during hot operation; another purpose of this invention is to provide a method for automatic bearing elevation adjustment based on the operating stage using electrostrictive materials.

[0005] Technical Solution: The automatic bearing elevation adjustment system based on electrostrictive materials of the present invention includes a signal acquisition unit, a signal processing and control unit, and several electrostrictive actuators. The signal processing and control unit receives input from the signal acquisition unit and calculates and outputs a control voltage based on the elevation deviation between adjacent bearings. The electrostrictive actuators are located between the bearing bush and the shim. The signal processing and control unit outputs a control voltage to apply the control voltage to the electrostrictive actuators to dynamically adjust the bearing elevation.

[0006] Furthermore, during the low-speed operation phase or cold start phase, the signal acquisition unit is used to acquire the bearing's top shaft oil pressure signal.

[0007] Furthermore, during the hot operation phase, the signal acquisition unit is used to acquire the lubricating oil temperature signal of the bearing.

[0008] Furthermore, the electrostrictive actuator is made of piezoelectric ceramic material and generates micron-level linear expansion and contraction displacement under the control voltage output by the signal processing and control unit.

[0009] Furthermore, the signal processing and control unit includes a PLC controller and a voltage amplifier.

[0010] Furthermore, the adjustment amount ΔH = d of the electrostrictive actuator 33 ×U×G, where d 33 U is the sensitivity coefficient of the electrostrictive material in the electrostrictive actuator, U is the output voltage of the PLC controller, and G is the gain of the voltage amplifier.

[0011] The automatic bearing elevation adjustment method based on electrostrictive materials described in this invention is implemented through the aforementioned automatic bearing elevation adjustment system. The specific automatic bearing elevation adjustment method is as follows:

[0012] (1) The signal acquisition unit acquires the bearing signal;

[0013] (2) The signal processing and control unit receives the input from the signal acquisition unit and calculates the output control voltage based on the elevation deviation between adjacent bearings;

[0014] (3) The electrostrictive actuator receives the signal processing and control unit outputs the control voltage, applies the control voltage to the electrostrictive actuator, and performs dynamic adjustment of the bearing elevation.

[0015] (4) The signal acquisition unit reacquires the bearing signal and determines whether there is an elevation deviation between adjacent bearings. If there is no elevation deviation, the bearing elevation adjustment is completed and the current output control voltage value is maintained. If there is an elevation deviation, the process returns to step (2).

[0016] Furthermore, during the low-speed operation phase or cold start phase, in step (1), the bearing signal acquired by the signal acquisition unit is the top shaft oil pressure data P of the adjacent bearing. 2k and P 2k+1 In step (2), the signal processing and control unit determines whether there is a pressure difference ΔP. If ΔP is not 0, it controls the low oil pressure side bearing electrostriction actuator to extend and raise the elevation until the pressure difference is eliminated.

[0017] Furthermore, during the hot operation phase, in step (1), the bearing signal acquired by the signal acquisition unit is the lubricating oil temperature signal T of the adjacent bearing. 2k and T 2k+1In step (2), the signal processing and control unit determines whether there is a temperature difference. If there is a temperature difference ΔT, the high temperature side becomes the low elevation side. The high oil temperature side bearing electrostriction actuator is controlled to extend and the elevation is raised until the temperature difference is eliminated, thus eliminating the bearing misalignment under hot conditions.

[0018] Furthermore, during the low-speed operation phase or cold start phase, the elevation deviation ΔB1 = K1 × |P 2k -P 2k+1 | where K1 is the displacement-pressure coefficient;

[0019] During the hot-state operation phase, the elevation deviation ΔB2 = K2 × |T 2k -T 2k+1 |, where K2 is the displacement-temperature coefficient.

[0020] Beneficial Effects: Compared with the prior art, the significant advantages of this invention are: 1. By embedding an electrostrictive actuator between the bearing bush and the shim, combined with sensor monitoring and PLC intelligent control, this invention achieves active dynamic adjustment of the bearing elevation, avoiding the traditional method of relying on manual adjustment of shims. This solves the vibration faults caused by unreasonable shaft elevation distribution, significantly improving the safety and adaptability of equipment operation; 2. The electrostrictive adjustment process of this invention does not affect the integrity of the bearing structure, does not require lifting the rotor or disassembling the bearing bush, and has online adjustment capability. Due to the fast response speed and high control precision of the electrostrictive material, combined with a voltage amplifier, micron-level elevation adjustment can be achieved to adapt to the shaft offset trend under different thermal conditions or load changes, effectively supporting the development needs of intelligent maintenance and remote monitoring; 3. This invention uses the top shaft oil pressure and lubricating oil temperature as the basis for judging elevation deviation, which can adapt to the dynamic changes of the unit under cold, hot and different operating conditions, ensuring the alignment accuracy of the shaft system, significantly reducing vibration and wear problems caused by uneven elevation distribution, and improving the stability and reliability of equipment operation. Attached Figure Description

[0021] Figure 1 This is a flowchart of the method of the present invention;

[0022] Figure 2 This is a schematic diagram of the installation of the electrostrictive actuator;

[0023] Figure 3 PLC terminal block diagram;

[0024] Figure 4 This is a schematic diagram of the shaft system. Detailed Implementation

[0025] The automatic bearing elevation adjustment system based on electrostrictive materials described in this invention includes a signal acquisition unit, a signal processing and control unit, and an electrostrictive actuator. During startup and operation, it can automatically adjust the bearing elevation online based on the difference in top shaft oil pressure or lubricating oil temperature at adjacent positions in the shaft system, thereby optimizing the load distribution at the support points, reducing the risk of misalignment, and improving the stability and intelligence level of the unit operation; wherein:

[0026] The signal acquisition unit includes multiple sensors for real-time acquisition of bearing condition data during system operation. Specifically, during the low-speed operation phase, pressure sensors installed in the oil circuits of each bearing's top shaft acquire the top shaft oil pressure signal; after entering the hot operation phase, temperature sensors located at the bearing's oil outlet acquire the lubricating oil temperature signal.

[0027] The signal processing and control unit uses a PLC as the core controller, receiving input signals of top shaft oil pressure or lubricating oil temperature, and outputting control voltage to each electrostrictive unit. The system selects different signal sources at different operating stages: at low speeds and with the top shaft oil pump running, it receives top shaft oil pressure signals from each bearing; after vacuuming and entering a loaded hot state, it switches to receiving lubricating oil temperature signals. The PLC compares the signal differences between adjacent bearings to determine if there is an elevation deviation. When the top shaft oil pressure of a bearing is lower than that of the adjacent bearing or the lubricating oil temperature is higher, it is determined that the bearing's elevation is too low. The PLC applies a preset voltage to the corresponding electrostrictive element to elongate it; when the preset target difference is reached, the output stops, achieving relative elevation consistency. If a reverse deviation occurs, the voltage can be appropriately reduced to encourage the material to return to its original length, forming a closed-loop control mechanism.

[0028] The electrostrictive actuator 2, composed of piezoelectric ceramic components, is embedded between the bearing bush 3 and the shim 1. When the PLC outputs voltage, the piezoelectric components generate micron-level linear telescopic displacement in the bearing area, achieving relative height adjustment between the bearing bush and the shim, thereby changing the actual elevation of the bearing. Multiple electrostrictive units can work together to achieve precise micro-adjustment of the elevation. This structure eliminates the need to disassemble the bearing and features high response speed and repeatability.

[0029] Specifically, one PLC controls two bearings, number 2k and 2k+1, receiving voltage or current signals from the corresponding pressure and temperature sensors of each bearing via analog input channels. The PLC is equipped with four AI interfaces, used to receive the top shaft oil pressure and lubricating oil temperature signals of the two bearings respectively.

[0030] Specifically, based on the judgment result, the PLC outputs a control voltage signal to the voltage amplifier through the analog output channel. Each bearing is equipped with three independent AO channels, which control the electrostrictive actuators in the bottom and left and right directions respectively, thereby precisely adjusting the bearing elevation. The PLC needs to be configured with a total of six AO interfaces corresponding to the electrostrictive actuators of bearings 2k and 2k+1.

[0031] Specifically, during the low-speed operation phase, the system collects hydraulic pressure data P from each bearing's top shaft. 2k P 2k+1 Determine whether there are bearing pairs with significant pressure differences, and use the pressure difference value ΔP = P 2k -P 2k+1 This serves as the basis for judging the relative height of the bearings. If ΔP > 0, the PLC controls the electrostriction unit of bearing 2k+1 to extend appropriately, raising its elevation; if ΔP < 0, the PLC controls the electrostriction unit of bearing 2k to extend appropriately, raising its bearing bush elevation until the top shaft oil pressure of each bearing is basically the same, completing the initial cold-state height adjustment. The formula for calculating the elevation deviation is ΔB1 = K1 × |P 2k -P 2k+1 |, where K1 is the displacement-pressure coefficient, k=1,2,3….

[0032] Specifically, during the hot operation phase, the system collects the lubricating oil temperature data T of each bearing. 2k T 2k+1， Determine if there are bearing pairs with significant temperature differences, and use the temperature difference value ΔT = T 2k -T 2k+1 This serves as the basis for judging the relative height of the bearings. If ΔT > 0, the PLC controls the electrostriction unit of bearing 2k to extend appropriately, raising its elevation; if ΔT < 0, the PLC controls the electrostriction unit of bearing 2k+1 to extend appropriately until the oil temperature difference is basically eliminated, thus achieving dynamic optimization of the shaft system's thermal alignment. The formula for calculating the elevation deviation is ΔB2 = K2 × |T 2k -T 2k+1 |, where K2 is the displacement-temperature coefficient, k=1,2,3….

[0033] Specifically, since the main bearings of large steam turbine generator sets are mostly divided into upper and lower halves, the lower half of the bearing is generally equipped with three adjusting shims, such as... Figure 2 As shown, there is one shim at the bottom and one shim on each side symmetrically. The center lines of the shims on the left and right sides form an angle β with the vertical center line. When the elevation deviation is ΔB, the adjustment amount of the bottom material is ΔH1 = ΔB, while the adjustment amount of the materials on the left and right sides is ΔH2 = ΔH3 = ΔB × cosβ.

[0034] Specifically, the PLC outputs a control signal that is amplified and applied to the electrodes of the electrostrictive material, creating an electric field that drives its length change. Based on the material's sensitivity coefficient d... 33 By combining the adjustment amount ΔH with the gain G of the voltage amplifier, the PLC output voltage can be calculated.

[0035] Specifically, after each round of elevation adjustment, the oil pressure difference or oil temperature difference between the bearings is collected and checked again to see if it is 0. If it is 0, the adjustment is considered complete, and the current output voltage value is maintained. If there is still a deviation, a further closed-loop judgment process is initiated.

[0036] Specifically, when the sign of the difference after this round of adjustment remains consistent with that of the previous round, it indicates that the elevation has not been fully adjusted. The system will then recalculate the target voltage value based on the required elevation compensation amount for the current residual deviation ΔH'. The PLC adjusts the output to further stretch the electrostrictive material, advancing the elevation adjustment process. When the sign of the difference after this adjustment is opposite to that of the previous one, it indicates an "over-adjustment" phenomenon. The system will then recalculate the target voltage value based on the required elevation compensation amount for the current residual deviation ΔH'. The electrostrictive material is caused to "retract" and its elevation is lowered, thus eliminating over-adjustment errors. This adjustment process can be executed iteratively to achieve closed-loop stable control and ensure precise alignment of the bearing elevation.

[0037] The present invention relates to an automatic bearing elevation adjustment method based on electrostrictive materials, which is implemented through the aforementioned automatic bearing elevation adjustment system. The specific method for automatic bearing elevation adjustment is as follows:

[0038] (1) The signal acquisition unit acquires the bearing signal; during the low-speed operation stage or cold start stage, the bearing signal acquired by the signal acquisition unit is the top shaft oil pressure data P of the adjacent bearing. 2k and P 2k+1 During the hot-state operation phase, the bearing signal acquired by the signal acquisition unit is the lubricating oil temperature signal T of the adjacent bearing. 2k and T 2k+1 .

[0039] (2) The signal processing and control unit receives the input from the signal acquisition unit and calculates the output control voltage based on the elevation deviation between adjacent bearings; during the low-speed operation stage or cold start stage, the signal processing and control unit calculates the elevation deviation ΔB1=K1×|P 2k -P 2k+1 |, where K1 is the displacement-pressure coefficient; during the hot operation phase, the signal processing and control unit calculates the elevation deviation ΔB2=K2×|T 2k -T 2k+1|, where K2 is the displacement-temperature coefficient. Based on the material's sensitivity coefficient d 33 By combining the adjustment amount ΔH with the gain G of the voltage amplifier, the PLC output voltage can be calculated. ΔH = ΔB1 or ΔH = ΔB2.

[0040] (3) The electrostrictive actuator receives the signal processing and control unit outputs the control voltage, applies the control voltage to the electrostrictive actuator, and performs dynamic adjustment of the bearing elevation.

[0041] (4) The signal acquisition unit reacquires the bearing signal and determines whether there is an elevation deviation between adjacent bearings. If there is no elevation deviation, the bearing elevation adjustment is completed and the current output control voltage value is maintained. If there is an elevation deviation, the process returns to step (2).

[0042] Taking a common shaft system of a 300MW unit as an example, the unit's shaft system is set to have a total of 7 bearings. Bearings 1 and 2 support the high and intermediate pressure cylinders, bearings 3 and 4 support the low pressure cylinders, bearings 5 ​​and 6 support the generator, and bearing 7 supports the exciter. See the shaft system diagram below. Figure 4 .

[0043] Assuming the material's sensitivity coefficient d 33 10 -7 m / V, the gain G of the voltage amplifier is 100, and the angle β between the center line of the left and right pads and the vertical center line is 75°.

[0044] During low-speed operation, read the oil pressure data P detected in real time by the jacking oil pressure sensor. 2k P 2k+1 Calculate the pressure difference ΔP = P 2k -P 2k+1 If the difference between bearings 2 and 3 is ΔP = P2 - P3 < 0, and the deviation calculated by the elevation plate formula ΔB = K1 × |P2 - P3| is 0.03 mm, then the adjustment amount of the bottom material ΔH1 = ΔB = 0.03 mm, and the adjustment amount of the materials on the left and right sides ΔH2 = ΔH3 = ΔB × cosβ = 0.00776 mm. The PLC determines that the elevation of bearing 2 needs to be raised, and the PLC output voltage...

[0045] During the hot operation phase, the oil temperature data T detected in real time by the lubricating oil temperature sensor is read. 2k T 2k+1 Calculate the temperature difference ΔT = T 2k -T 2k+1If the difference in elevation between bearings 4 and 5 is ΔT = T4 - T5 < 0, and the elevation deviation calculated using the formula ΔB = K2 × |T4 - T5| is 0.02 mm, then the adjustment amount for the bottom material is ΔH1 = ΔB = 0.02 mm, while the adjustment amounts for the materials on the left and right sides are ΔH2 = ΔH3 = ΔB × cosβ = 0.00518 mm. The PLC determines that the elevation of bearing 5 needs to be raised, and the PLC output voltage...

Claims

1. An electrostrictive material based bearing ride height automatic adjustment system, characterized by, It comprises a signal acquisition unit, a signal processing and control unit and several electrostrictive execution units; the signal processing and control unit is used for receiving the input of the signal acquisition unit, calculating the output control voltage according to the elevation deviation between adjacent bearings; the electrostrictive execution unit is located between the bearing bush and the pad iron, the signal processing and control unit outputs the control voltage, the electrostrictive execution unit is applied with the control voltage, and the dynamic adjustment of the bearing elevation is carried out.

2. The electrostrictive bearing height automatic adjustment system based on electrostrictive material according to claim 1, characterized in that, In the low-speed running stage or the cold-state starting stage, the signal acquisition unit is used for acquiring the top shaft oil pressure signal of the bearing.

3. The electrostrictive bearing height automatic adjustment system based on electrostrictive material according to claim 1, characterized in that, In the hot-state running stage, the signal acquisition unit is used for acquiring the lubricating oil temperature signal of the bearing.

4. The electrostrictive bearing height automatic adjustment system based on electrostrictive material according to claim 1, characterized in that, The electrostrictive execution unit is composed of piezoelectric ceramic material.

5. The electrostrictive bearing height automatic adjustment system based on electrostrictive material according to claim 1, characterized in that, The signal processing and control unit comprises a PLC controller and a voltage amplifier.

6. The electrostrictive bearing height automatic adjustment system based on electrostrictive material according to claim 5, characterized in that, The adjustment amount ΔH of the electrostrictive actuator = d 33 × U × G, where d 33 is the sensitivity coefficient of the electrostrictive material of the electrostrictive actuator, U is the output voltage of the PLC controller, and G is the gain of the voltage amplifier.

7. A method for automatic adjustment of bearing elevation based on electrostrictive material, characterized by, The bearing elevation automatic adjustment method is realized by the bearing elevation automatic adjustment system of any one of claims 1-6, and specifically as follows: (1) the signal acquisition unit acquires the bearing signal; (2) the signal processing and control unit receives the input of the signal acquisition unit, calculates the output control voltage according to the elevation deviation between adjacent bearings; (3) the electrostrictive execution unit receives the output control voltage of the signal processing and control unit, applies the control voltage to the electrostrictive execution unit, and carries out the dynamic adjustment of the bearing elevation; (4) the signal acquisition unit reacquires the bearing signal, judges whether there is an elevation deviation between adjacent bearings, if there is no elevation deviation, the bearing elevation adjustment is completed, and the current output control voltage value is maintained; if there is an elevation deviation, it returns to step (2).

8. The method of claim 7, wherein the step of automatically adjusting the bearing elevation comprises the step of: In the low-speed running stage or cold start stage, in step (1), the bearing signal acquired by the signal acquisition unit is the top shaft oil pressure data P of the adjacent bearing 2k and P 2k+1 ; in step (2), the signal processing and control unit judges whether there is a pressure difference ΔP, and if ΔP is not 0, the low oil pressure side bearing electrostrictive actuator is controlled to elongate to increase the elevation until the pressure difference is eliminated. ​ 9. The method of claim 8, wherein the step of automatically adjusting the bearing height of the electrostrictive material-based bearing is performed by a controller. In the hot running stage, in step (1), the bearing signal acquired by the signal acquisition unit is the lubricating oil temperature signal T of the adjacent bearing 2k and T 2k+1 ; in step (2), the signal processing and control unit judges whether there is a temperature difference, if there is a temperature difference ΔT, the high side is the high side, and the high oil temperature side bearing electrostrictive actuator is elongated to adjust the height until the temperature difference is eliminated, and the bearing misalignment under the hot state is eliminated.

10. The bearing elevation automatic adjustment method based on electrostrictive material according to claim 9, characterized in that, In the low speed running stage or cold start stage, the elevation deviation amount ΔB1 = K1 x |P 2k - P 2k+1 |, wherein K1 is a displacement-pressure coefficient; In the hot operating phase, the elevation deviation amount ΔB2 = K2 x |T 2k -T 2k+1 |, where K2 is the displacement-temperature coefficient.

Images