Multi-stage centrifugal pump with magnetic balance device

Abstract

The invention belongs to the technical field of multi-stage centrifugal pumps, and particularly relates to a multi-stage centrifugal pump with a magnetic balance device, which comprises a pump body, a main shaft, at least two stages of impellers connected in series with the main shaft, a driving motor and a magnetic balance unit, and the magnetic balance unit comprises a driving magnetic ring on the main shaft, a driven magnetic ring on the inner wall of the pump body and an electromagnetic adjusting unit integrated on the driven magnetic ring. The two form a repulsive magnetic field, so that axial and radial non-contact suspension of the impeller assembly is realized; the electromagnetic adjusting unit is connected with the control system, the system comprises a displacement detection module, a vibration detection module, a temperature detection module and a current detection module, and the magnetic field intensity is dynamically adjusted by generating correlation coefficients and comprehensive evaluation coefficients and comparing the correlation coefficients and the comprehensive evaluation coefficients with preset threshold values. Mechanical abrasion can be reduced, efficient, stable and safe operation of equipment is guaranteed through real-time monitoring and graded protection, and the device is suitable for the scene where liquid needs to be reliably conveyed for a long time.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of multistage centrifugal pumps, and in particular to a multistage centrifugal pump with a magnetic balancing device. BACKGROUND

[0002] In the operation process of the existing multistage centrifugal pump, mechanical contact problems exist between the core moving parts and the fixed parts, which are specifically manifested as that mechanical wear is easily caused between the rotatable pump body and the shell and between the impeller and the rotatable pump body due to the lack of effective non-contact balancing structure, and the mechanical wear not only shortens the service life of the core parts such as the pump body and the impeller, but also causes abnormal changes in the running gap due to the wear of the parts, thereby affecting the conveying efficiency and the operation stability of the pump.

[0003] Meanwhile, referring to the existing application No. 202511342007.6, a rotatable pump body structure liquid ring vacuum pump is disclosed, and the related structure idea in the patent has involved the optimization of the rotatable parts, but the technology is not adapted to the working condition characteristics of the multistage centrifugal pump, and the basic principle of the "multistage magnetic device" has not been effectively applied in the existing multistage centrifugal pump field, that is, repulsion is generated by magnetic force when the parts are close, and attraction is generated when the parts are far away, so as to realize the suspended state of "neither contacting the metal shell nor being far away".

[0004] The current multistage centrifugal pump mainly depends on the traditional mechanical bearing and other contact type supporting structures, and even if some improved schemes try to reduce the wear, it is difficult to realize the stable non-contact suspension between the rotatable parts (such as the impeller and the rotatable pump body) and the fixed shell near the main shaft, and the mechanical wear problem cannot be fundamentally solved, so the application provides a multistage centrifugal pump with a magnetic balancing device. SUMMARY

[0005] Based on the technical problems existing in the prior art, the application provides a multistage centrifugal pump with a magnetic balancing device.

[0006] This invention discloses a multi-stage centrifugal pump with a magnetic balancing device, comprising a pump body, a main shaft, at least two impellers connected in series on the main shaft, and a drive motor. A magnetic balancing unit is disposed between the main shaft and the pump body. The magnetic balancing unit includes an active magnetic ring fixed on the main shaft, a driven magnetic ring fixed on the inner wall of the pump body, and an electromagnetic adjustment unit. The active and driven magnetic rings are arranged coaxially opposite each other and form a repulsive magnetic field to apply a non-contact levitation balancing force to the impeller assembly in the axial and radial directions of the main shaft. The electromagnetic adjustment unit is integrated in the driven magnetic ring and can adjust the magnetic field strength according to a control signal. The drive motor drives the main shaft to rotate, and the at least two impellers connected in series on the main shaft rotate synchronously to achieve liquid delivery. The active magnetic ring rotates with the main shaft and forms a coaxially opposite repulsive magnetic field with the driven magnetic ring fixed on the inner wall of the pump body, applying a non-contact levitation balancing force to the impeller assembly in the axial and radial directions of the main shaft. The electromagnetic adjustment unit adjusts the magnetic field strength in real time according to the control signal to ensure that the impeller assembly operates stably within a preset range.

[0007] Preferably, the electromagnetic adjustment unit is further connected to a control system, which includes: a displacement detection module for real-time monitoring of the gap between the impeller and the pump body, and generating a gap stability coefficient through the control module; a vibration detection module for real-time monitoring of pump body vibration, reflecting the smoothness of impeller operation, and generating a vibration level coefficient through the control module; a temperature detection module for real-time monitoring of operating temperature, preventing overheating and wear, and generating a temperature change coefficient through the control module; and a current detection module for real-time monitoring of motor load current, reflecting the system operating load, and generating a current fluctuation coefficient through the control module. The displacement detection module monitors the gap between the impeller and the pump body in real-time and generates a gap stability coefficient; the vibration detection module monitors pump body vibration in real-time and generates a vibration level coefficient; the temperature detection module monitors operating temperature in real-time and generates a temperature change coefficient; and the current detection module monitors motor load current in real-time and generates a current fluctuation coefficient. The control module performs a comprehensive analysis of the above four coefficients to generate an evaluation coefficient, compares the evaluation coefficient with a pre-set reference threshold, and sends a corresponding control signal to the electromagnetic adjustment unit based on the comparison result to adjust the magnetic field strength to dynamically balance the force state of the impeller assembly, ensuring the efficient and stable operation of the multi-stage centrifugal pump.

[0008] Preferably, the output and input terminals of the displacement detection module, the vibration detection module, the temperature detection module, and the current detection module are electrically connected to the input and output terminals of the control module, respectively, and the output terminal of the control module is electrically connected to the input terminal of the electromagnetic adjustment unit.

[0009] Preferably, the steps by which the control module controls the working state of the electromagnetic adjustment unit based on the comparison results are as follows: The displacement detection module collects the gap between the impeller and the pump body; the vibration detection module collects the pump body vibration; the temperature detection module collects the operating temperature; the current detection module collects the motor load current; the control module calculates the gap stability coefficient, vibration level coefficient, temperature change coefficient, current fluctuation coefficient, and evaluation coefficient; if the evaluation coefficient is less than or equal to the first-level threshold and all sub-coefficients are normal, the current parameters are maintained; if the evaluation coefficient is greater than the first-level threshold or any sub-coefficient exceeds the preset value, an audible and visual warning is issued, the magnetic balance current is finely adjusted, and the high-frequency monitoring mode is activated; if the evaluation coefficient is greater than the second-level threshold or two or more sub-coefficients continue to exceed the standard, the warning level is raised, and the pump speed is automatically reduced by 10-20%; if the evaluation coefficient is greater than the third-level threshold or a sudden change is detected, the pump is immediately and smoothly shut down, the main power supply is cut off, the magnetic balance device maintains protective suspension, and the emergency pressure relief valve is triggered.

[0010] Preferably, the logic for generating the gap stability coefficient is as follows: The actual gap value at different times within a set time period T is obtained by the displacement detection module; based on the deviation of the actual gap value at each time from the average gap value within the time period T, the gap stability coefficient reflecting the gap fluctuation is calculated.

[0011] Preferably, the generation logic of the vibration level coefficient is as follows: The vibration detection module obtains the actual vibration acceleration values ​​at different times within a set time period T; based on the deviation of the actual vibration acceleration value at each time from its average vibration acceleration value within the time period T, the vibration level coefficient, which reflects the fluctuation of vibration intensity, is calculated.

[0012] Preferably, the logic for generating the temperature change coefficient is as follows: The highest and lowest temperatures within the sampling period are obtained through a temperature detection module; based on the relationship between the temperature difference between the highest and lowest temperatures and the sampling time, a temperature change coefficient reflecting the degree of temperature change is calculated.

[0013] Preferably, the logic for generating the current fluctuation coefficient is as follows: The actual operating current value at different times within a set time period T is obtained through the current detection module; based on the deviation of the actual operating current value at each time from its average operating current value within the time period T, the current fluctuation coefficient reflecting the stability of the current is calculated.

[0014] Preferably, the logic for generating the evaluation coefficients is as follows: The control module performs comprehensive calculations using coupling gap stability coefficient, vibration level coefficient, temperature change coefficient, and current fluctuation coefficient, combined with the preset weights corresponding to each coefficient, to generate quantitative indicators for evaluating the overall state of the system.

[0015] Compared with the prior art, the present invention provides a multi-stage centrifugal pump with a magnetic balancing device, which has the following advantages: Non-contact levitation is achieved through the repulsive magnetic field of the magnetic balance unit, which completely reduces mechanical wear between components and extends the service life of core components such as pump body and impeller.

[0016] It integrates multiple detection modules and electromagnetic adjustment units to monitor gap, vibration, temperature and current status in real time, dynamically adjust the magnetic field strength, ensure stable operation of the impeller assembly within the preset range, and improve equipment operating efficiency.

[0017] It has a graded early warning and emergency protection mechanism, which triggers different levels of adjustment or shutdown measures based on the assessment coefficient, effectively preventing risks such as overload and overheating, and improving the safety of equipment operation.

[0018] The electromagnetic coil is independently controlled, allowing for targeted magnetic field compensation to adapt to different stress requirements under various working conditions and enhance the equipment's adaptability to different operating conditions. Attached Figure Description

[0019] Figure 1 This is a cross-sectional view of a multi-stage centrifugal pump with a magnetic balancing device proposed in this invention. Figure 2 For the present invention Figure 1 A magnified structural diagram at point A; Figure 3 This is a side view of a multi-stage centrifugal pump with a magnetic balancing device proposed in this invention; Figure 4 This is a system block diagram of a multi-stage centrifugal pump with a magnetic balancing device proposed in this invention.

[0020] In the diagram: 1. Pump body; 2. Main shaft; 3. Impeller; 4. Driving magnetic ring; 5. Driven magnetic ring. Detailed Implementation

[0021] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0022] In the description of this invention, it should be understood that the terms "upper", "lower", "front", "rear", "left", "right", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0023] Example 1, referring to Figures 1-3A multi-stage centrifugal pump with a magnetic balancing device includes a pump body 1, a rotating main shaft 2 installed inside the pump body 1, at least two impellers 3 connected in series on the main shaft 2, and a drive motor installed at the end of the pump body 1 to drive the main shaft 2 to rotate. A magnetic balancing unit is provided between the main shaft 2 and the pump body 1 near the last impeller 3. The magnetic balancing unit includes: The active magnetic ring 4 is a ring structure with an inner diameter that is interference-fitted with the outer diameter of the main shaft 2 (interference amount 0.01-0.03mm), an axial length of 15-30mm, and a radial thickness of 8-15mm. The magnetic ring has 2-8 pairs of magnetic poles evenly distributed along the circumference and is axially magnetized. The polarities of adjacent magnetic poles are alternated (N pole-N pole relative to the driven magnetic ring 5) to ensure that a uniform coaxial repulsive magnetic field is formed with the driven magnetic ring 5. The active magnetic ring 4 is assembled on the shoulder of the main shaft 2 near the last stage impeller 3. The two ends of the axial direction are positioned by locking nuts (made of 304 stainless steel) and anti-loosening washers. The locking torque is 15-25N・m to prevent the magnetic ring from axially moving or circumferentially slipping when the main shaft 2 rotates at high speed.

[0024] The driven magnetic ring 5 is fixed to the inner wall of the pump body 1 by an annular bracket (made of 316L stainless steel). The bracket and the pump body 1 are connected by M6-M8 hexagon socket bolts with a bolt spacing of 45-60°. The coaxiality error between the driven magnetic ring 5 and the driving magnetic ring 4 is ≤0.02mm, the axial alignment deviation is ≤0.5mm, and the radial clearance is controlled at 0.5-2.0mm (adapted according to the rated flow of the pump body 1 and the diameter of the impeller 3; the larger the flow, the smaller the clearance).

[0025] The electromagnetic adjustment unit, embedded in the annular iron core of the driven magnetic ring 5, consists of an electromagnetic coil winding, an iron core slot, and terminals. The iron core slots are evenly spaced along the circumference of the annular iron core, with the number corresponding to the permanent magnet ring segments (2-8). Each slot contains an independent electromagnetic coil. The electromagnetic adjustment unit is powered by 12-24V DC from the control system, with a current adjustment range of 0.1-1A. Precise current control is achieved through PWM (Pulse Width Modulation), with a response time ≤5ms. Each electromagnetic coil is independently controlled and can adjust the current intensity of the corresponding coil according to the force offset of the impeller 3 in different directions, thereby achieving directional compensation of the magnetic field.

[0026] Working principle: The drive motor drives the main shaft 2 to rotate, and at least two impellers 3 connected in series on the main shaft 2 rotate synchronously to realize liquid transportation; the active magnetic ring 4 rotates together with the main shaft 2, forming a coaxial and opposite repulsive magnetic field with the driven magnetic ring 5 fixed on the inner wall of the pump body 1, applying a non-contact levitation balancing force to the impeller 3 assembly in the axial and radial directions of the main shaft 2. The electromagnetic adjustment unit adjusts the magnetic field strength in real time according to the control signal to ensure that the impeller 3 assembly operates stably within the preset range.

[0027] Example 2, refer to Figure 4The present invention also provides a control system for the electromagnetic adjustment unit, the control system comprising: The displacement detection module is installed inside the pump body 1 near the edge of the impeller 3, with 3 to 4 modules evenly arranged along the circumference. It is used to monitor the gap between the impeller 3 and the pump body 1 in real time and generate the gap stability coefficient through the control module. The vibration detection module is installed on the outside of the pump body 1 near the bearing seat. It is used to monitor the vibration of the pump body 1 in real time, reflect the smoothness of the impeller 3 operation, and generate the vibration level coefficient through the control module. The temperature detection module is installed near the outer ring of the bearing or the stator of the motor to monitor the operating temperature in real time, prevent overheating and wear, and generate a temperature change coefficient through the control module. The current detection module is installed on the motor power supply line to monitor the motor load current in real time, reflect the system operating load, and generate the current fluctuation coefficient through the control module. The control module performs a comprehensive analysis of the generated gap stability coefficient, vibration level coefficient, temperature change coefficient, and current fluctuation coefficient to generate an evaluation coefficient. The evaluation coefficient is then compared with a pre-set reference threshold, and the working state of the electromagnetic adjustment unit is controlled based on the comparison results.

[0028] In this invention, the output and input terminals of the displacement detection module, the vibration detection module, the temperature detection module, and the current detection module are electrically connected to the input and output terminals of the control module, respectively, and the output terminal of the control module is electrically connected to the input terminal of the electromagnetic adjustment unit.

[0029] It should be noted that the displacement detection module can be an eddy current displacement sensor or other device capable of real-time monitoring of the gap between the impeller 3 and the pump body 1; the vibration detection module can be a piezoelectric vibration sensor or other device capable of real-time monitoring of the vibration of the pump body 1; the temperature detection module can be a PT100 platinum resistance temperature sensor or other device capable of real-time monitoring of the operating temperature; the current detection module can be a Hall current sensor or other device capable of real-time monitoring of the motor load current; and the control module is an embedded controller, such as the STM32 series, which integrates PID control algorithms and data fusion logic. Therefore, the displacement detection module, vibration detection module, and control module are not specifically limited here and can be selected according to actual needs.

[0030] During operation, the displacement detection module monitors the gap between the impeller 3 and the pump body 1 in real time and generates a gap stability coefficient; the vibration detection module monitors the vibration of the pump body 1 in real time and generates a vibration level coefficient; the temperature detection module monitors the operating temperature in real time and generates a temperature change coefficient; and the current detection module monitors the motor load current in real time and generates a current fluctuation coefficient. The control module performs a comprehensive analysis of the above four coefficients to generate an evaluation coefficient, compares the evaluation coefficient with a pre-set reference threshold, and sends a corresponding control signal to the electromagnetic adjustment unit based on the comparison result to adjust the magnetic field strength to dynamically balance the force state of the impeller 3 assembly, ensuring the efficient and stable operation of the multi-stage centrifugal pump.

[0031] Furthermore, in this invention, the execution steps of the control module controlling the working state of the electromagnetic adjustment unit based on the comparison results are as follows: Real-time detection: The displacement detection module collects the gap between the impeller 3 and the pump body 1; the vibration detection module collects the vibration of the pump body 1; the temperature detection module collects the operating temperature; and the current detection module collects the motor load current. Coefficient calculation: Gap stability coefficient G σ The clearance stability coefficient reflects the degree of fluctuation between the impeller 3 and the pump body 1, characterizing the control effect of the magnetic balance device. In this invention, the logic for generating the clearance stability coefficient is as follows: S1. Obtain the actual gap values ​​at different times within time T using the displacement detection module, and calibrate the actual gap value obtained at time i within time T as G. i , i = 1, 2, 3, ..., N, where i is a positive integer; S2. Calculate the gap stability coefficient. The expression for the calculation is: In the formula, G is the average pressure over time T; N is the number of samples taken over time T.

[0032] Vibration level coefficient A σ The vibration level coefficient reflects the intensity of pump body 1 vibration and indirectly reflects the dynamic balance state of impeller 3. In this invention, the generation logic of the vibration level coefficient is as follows: S1. Obtain the actual vibration acceleration values ​​at different times within time T using the vibration detection module, and calibrate the actual vibration acceleration value obtained at time j within time T as A. j j = 1, 2, 3, ..., M, where j is a positive integer; S2. Calculate the vibration level coefficient. The expression for the calculation is: In the formula, A is the average vibration acceleration value within time T; M is the number of samplings within time T.

[0033] Temperature variation coefficient Θ Δ: Reflects the rate of temperature rise, used for early warning of abnormal friction or overload; in this invention, the generation logic of the temperature change coefficient is as follows: S1. Obtain the highest temperature Θmax and lowest temperature Θmin within the sampling period through the temperature detection module; S2. Calculate the temperature change coefficient. The expression for the calculation is: In the formula, t sample This refers to the sampling duration.

[0034] Current fluctuation coefficient I σ The stability of the drive motor load is quantified, indirectly reflecting the changes in the impeller 3's rotational resistance, magnetic balance state, and internal fluid dynamics. In this invention, the logic for generating the current fluctuation coefficient is as follows: S1. Obtain the actual operating current values ​​at different times within time T using the current detection module, and calibrate the actual operating current value obtained at time k within time T as I. k k = 1, 2, 3, ..., P, where k is a positive integer; S2. Calculate the current fluctuation coefficient. The expression for the calculation is: In the formula, I is the average operating current value within time T; P is the number of samplings within time T.

[0035] Evaluation coefficient: The above sub-coefficients are weighted and fused to generate a dimensionless index for quantifying the overall operational instability or health risk level of the system; in this invention, a formulaic analysis is performed through the control module, based on the formula: In the formula, α, β, γ, and δ are the weighting coefficients of gap, vibration, temperature, and current, respectively (dynamically determined by combining experimental data and process requirements; the optimal α, β, γ, and δ are ultimately determined through a closed-loop iterative process of initial theoretical assignment → on-site operation testing → observation of effects → fine-tuning parameters. This process is the standard practice for debugging industrial automation systems, so it will not be elaborated further.), satisfying α + β + γ + δ = 1.

[0036] Dynamic adjustment: If E bp ≤E th1 And all sub-coefficients are normal, maintain the current parameters, and record the running data; if E bp >E th1 If any sub-coefficient exceeds the preset value, an audible and visual alarm will be triggered, abnormal data will be recorded in the background, the magnetic balance current will be fine-tuned, and the high-frequency monitoring mode will be activated; if E bp >E th2 If two or more sub-coefficients continuously exceed the standard, the warning level will be raised, the pump speed will be automatically reduced by 10-20%, and an alarm message will be sent to the monitoring center; if Ebp >E th3 If a sudden change is detected (such as a sudden increase in current or excessive vibration intensity), the machine will immediately and smoothly shut down, disconnect the main power supply, maintain the magnetic balance device in protective levitation, and trigger the emergency pressure relief valve; among which, E th1 <E th2 <E th3 This is a three-level threshold.

[0037] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A multistage centrifugal pump with a magnetic balancing device, comprising a pump body (1), a main shaft (2), at least two impellers (3) connected in series on the main shaft (2), and a drive motor, characterized in that, A magnetic balancing unit is provided between the main shaft (2) and the pump body (1); the magnetic balancing unit includes an active magnetic ring (4) fixed on the main shaft (2), a driven magnetic ring (5) fixed on the inner wall of the pump body (1) and an electromagnetic adjustment unit; the active magnetic ring (4) and the driven magnetic ring (5) are arranged coaxially opposite to each other and form a repulsive magnetic field to apply a non-contact levitation balancing force to the impeller (3) assembly in the axial and radial directions of the main shaft (2); the electromagnetic adjustment unit is integrated in the driven magnetic ring (5) and can adjust the magnetic field strength according to the control signal.

2. A multi-stage centrifugal pump with a magnetic balance device according to claim 1, characterized in that, The electromagnetic adjustment unit is also connected to a control system, which includes: The displacement detection module is used to monitor the gap between the impeller (3) and the pump body (1) in real time, and to generate the gap stability coefficient through the control module; The vibration detection module is used to monitor the vibration of the pump body (1) in real time, reflect the smooth operation of the impeller (3), and generate the vibration level coefficient through the control module. The temperature detection module is used to monitor the operating temperature in real time, prevent overheating and wear, and generate a temperature change coefficient through the control module; The current detection module is used to monitor the motor load current in real time, reflect the system operating load, and generate the current fluctuation coefficient through the control module. The control module performs a comprehensive analysis of the generated gap stability coefficient, vibration level coefficient, temperature change coefficient, and current fluctuation coefficient to generate an evaluation coefficient. The evaluation coefficient is then compared with a pre-set reference threshold, and the working state of the electromagnetic adjustment unit is controlled based on the comparison results.

3. A multi-stage centrifugal pump with a magnetic balance device according to claim 2, characterized in that, The output and input terminals of the displacement detection module, the vibration detection module, the temperature detection module, and the current detection module are electrically connected to the input and output terminals of the control module, respectively. The output terminal of the control module is electrically connected to the input terminal of the electromagnetic adjustment unit.

4. A multi-stage centrifugal pump with a magnetic balance device according to claim 2, characterized in that, The steps by which the control module controls the working state of the electromagnetic adjustment unit based on the comparison results are as follows: Real-time detection: The displacement detection module collects the gap between the impeller (3) and the pump body (1); the vibration detection module collects the vibration of the pump body (1); the temperature detection module collects the operating temperature; and the current detection module collects the motor load current. Coefficient Calculation: The control module calculates the gap stability coefficient, vibration level coefficient, temperature change coefficient, current fluctuation coefficient, and evaluation coefficient; Dynamic adjustment: If the evaluation coefficient is less than or equal to the first-level threshold and all sub-coefficients are normal, maintain the current parameters; if the evaluation coefficient is greater than the first-level threshold or any sub-coefficient exceeds the preset value, issue an audible and visual warning, fine-tune the magnetic balance current, and activate the high-frequency monitoring mode; if the evaluation coefficient is greater than the second-level threshold or two or more sub-coefficients continue to exceed the limit, upgrade the warning level and automatically reduce the pump speed by 10-20%. If the evaluation coefficient exceeds the level 3 threshold or a sudden change is detected, the system will immediately shut down smoothly, the main power supply will be cut off, the magnetic balance device will maintain protective levitation, and the emergency pressure relief valve will be triggered.

5. A multi-stage centrifugal pump with a magnetic balance device according to claim 2, characterized in that, The logic for generating the gap stability coefficient is as follows: The actual gap value at different times within a set time period T is obtained by the displacement detection module; based on the deviation of the actual gap value at each time from the average gap value within the time period T, the gap stability coefficient reflecting the gap fluctuation is calculated.

6. A multi-stage centrifugal pump with a magnetic balance device according to claim 2, characterized in that, The generation logic of the vibration level coefficient is as follows: The vibration detection module obtains the actual vibration acceleration values ​​at different times within a set time period T; based on the deviation of the actual vibration acceleration value at each time from its average vibration acceleration value within the time period T, the vibration level coefficient, which reflects the fluctuation of vibration intensity, is calculated.

7. A multi-stage centrifugal pump with a magnetic balance device according to claim 2, characterized in that, The logic for generating the temperature change coefficient is as follows: The highest and lowest temperatures within the sampling period are obtained through a temperature detection module; based on the relationship between the temperature difference between the highest and lowest temperatures and the sampling time, a temperature change coefficient reflecting the degree of temperature change is calculated.

8. A multi-stage centrifugal pump with a magnetic balance device according to claim 2, characterized in that, The logic for generating the current fluctuation coefficient is as follows: The actual operating current value at different times within a set time period T is obtained through the current detection module; based on the deviation of the actual operating current value at each time from its average operating current value within the time period T, the current fluctuation coefficient reflecting the stability of the current is calculated.

9. A multi-stage centrifugal pump with a magnetic balance device according to claim 2, characterized in that, The logic for generating the evaluation coefficients is as follows: The control module performs comprehensive calculations using coupling gap stability coefficient, vibration level coefficient, temperature change coefficient, and current fluctuation coefficient, combined with the preset weights corresponding to each coefficient, to generate quantitative indicators for evaluating the overall state of the system.

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