CN102410240B - Dynamic balance method of magnetic molecular pump - Google Patents

Abstract

A method for dynamic balancing of a magnetic levitation molecular pump. After the magnetic levitation molecular pump motor is started, the force control unbalanced vibration control module is turned on. If under the control of the force control unbalanced vibration control module, the unbalanced mass on the rotor makes the rotor speed up If the maximum radial amplitude in the process does not exceed 1/2 of the protection gap, then the unbalanced vibration control module can suppress the same-frequency vibration of the rotor, so that the rotor speed can quickly exceed its rigid critical speed, so that the magnetic levitation can be controlled at a higher speed The rotor of the molecular pump is dynamically balanced. The dynamic balancing method of the present invention can directly perform a dynamic balancing operation on the rotor of the magnetic levitation molecular pump at high speed, and has simple steps and high efficiency.

Description

A method for dynamic balancing of magnetic levitation molecular pump

technical field

The invention relates to the technical field of vacuum obtaining equipment, in particular to a method for dynamic balancing of a magnetic levitation molecular pump.

Background technique

Molecular pump is a kind of vacuum pump, which uses high-speed rotating rotor impeller to transfer momentum to gas molecules to obtain directional speed, so that the gas is compressed and driven to the exhaust port, and then pumped away by the backing pump . The magnetic levitation molecular pump is a molecular pump that uses magnetic bearings (also known as active magnetic levitation bearings) as the molecular pump rotor support. Contact has the advantages of no mechanical wear, low energy consumption, high allowable speed, low noise, long life, and no need for lubrication. At present, magnetic levitation molecular pumps are widely used in the fields of obtaining high vacuum and high cleanliness vacuum environments.

The internal structure of the magnetic levitation molecular pump is shown in FIG. 1 . The rotor of the magnetic levitation molecular pump includes a rotor shaft 7 and an impeller 1 fixedly connected to the rotor shaft 7 . The impeller 1 is fixedly mounted on the upper part of the rotor shaft 7; the rotor shaft 7 is provided with a first radial magnetic bearing 6, a motor 8, a second radial magnetic bearing 9 and other devices at intervals. The devices jointly constitute the rotor shaft system of the magnetic levitation molecular pump.

After the assembly of the magnetic levitation molecular pump is completed, due to the difference in machining accuracy of the rotor parts, there will be unbalanced mass on the rotor (unbalanced mass refers to the mass at a specific radius of the rotor, and the product of this mass and the centripetal acceleration is equal to Unbalanced centrifugal force.), when the unbalanced mass is much greater than 10 mg, the unbalanced mass will cause an obvious eccentric moment between the center of gravity and the axis of the rotor, and the centrifugal inertia caused by the unbalanced mass of the rotor The force will cause transverse mechanical vibration (usually radial vibration) of the rotor and affect the normal operation of the system. In addition, the normal working speed of the rotor of the magnetic levitation molecular pump is in the high-speed region exceeding the rigid critical speed of the rotor. The above-mentioned unbalanced mass will cause the speed of the rotor to not be directly increased to its working speed, and the magnetic levitation molecular pump cannot work normally. Among them, the rigid critical speed of the rotor refers to the corresponding rotational speed when the rotational frequency of the rotor is equal to the rigid resonance frequency of the rotor bearing system; and the high-speed region exceeding the rigid critical speed of the rotor can be called the super rigid critical speed region.

In the prior art, there is a method that can suppress the unbalanced vibration generated during the speed-up and speed-down of the rotor and other high-speed rotating bodies in the magnetic levitation rotor system, which is called "unbalance vibration control method". For example, two kinds of unbalanced vibrations are introduced in the Chinese journal "Methods of Controlling Unbalanced Vibration of Magnetic Suspension Bearing System" (Zhang Dekui, Jiang Wei, Zhao Hongbin, Journal of Tsinghua University (Natural Science Edition) 2000, Vol. 40, No. 10). Control method: one is force free control, the basic idea is to generate a compensation signal with the same phase and amplitude as the rotor displacement/vibration signal, which is used to offset the same frequency signal of rotor vibration, so that the controller can synchronize The vibration signal does not respond; the other is open loop feedforward control (or force control), the basic idea of which is to extract the same frequency vibration component of the rotor vibration signal, and then generate it by another feedforward control The corresponding control signal is superimposed on the control signal of the main controller.

For example, Chinese patent document CN101261496A discloses a high-precision active vibration control system for a magnetic levitation flywheel, including a displacement sensor, a current sensor, a magnetic bearing controller and a magnetic bearing power amplifier. The magnetic bearing controller includes stability controller, eccentricity estimation, magnetic force compensation and action switch. On the basis of stability control, this patent introduces eccentricity estimation and magnetic compensation, and uses the unbalanced vibration parameters of the flywheel to compensate the unbalanced amount and displacement negative stiffness in the entire speed range of the flywheel, so as to realize the unbalanced vibration of the flywheel in the entire speed range control, so that the flywheel can rotate around the inertial spindle with high precision during the whole process of speed up and down. Another example is the Chinese patent document CN101046692A which discloses a magnetic levitation reaction flywheel open-loop high-precision unbalanced vibration control system, including a displacement sensor, a displacement signal interface circuit, a speed detection device, a magnetic bearing controller, a magnetic bearing power amplification drive circuit and a flywheel location identification device. The magnetic bearing controller includes an axial magnetic bearing controller and a radial magnetic bearing controller. The radial magnetic bearing controller is composed of a stability controller and an unbalanced vibration controller. Displacement feedback for compensation. On the basis of stability control, the unbalance vibration control is introduced, and the unbalance vibration parameters of the flywheel identified when the flywheel is at high speed, combined with the current position of the flywheel rotor obtained by the flywheel position identification device, is used to perform open-loop high-precision unbalance for the entire flywheel speed range. Vibration control, so as to realize the unbalanced vibration control of the flywheel in the whole speed range, so that the flywheel can run with high precision during the whole speed up and down process.

The above two patent documents are specific applications of the "unbalanced vibration control method". However, due to the limited adjustment and control force of the "unbalanced vibration control method", the rotation can only be suppressed when the unbalanced mass of the rotating body is within a certain threshold range. The unbalanced vibration of the body, that is to say, the "unbalanced vibration control method" cannot completely solve the problem of rotor vibration caused by the existence of unbalanced mass. Therefore, when the rotor has a large unbalanced mass, the "unbalanced vibration control method" cannot be used to achieve vibration suppression, so that the speed of the rotor directly exceeds the critical speed of the rotor rigidity and reaches its normal operating speed.

Therefore, after the magnetic levitation molecular pump is assembled, the rotor must be dynamically balanced. The so-called "dynamic balance" means that the rotor with unbalanced mass is corrected and eliminated after measuring the size and phase of the unbalanced mass. , so that the rotor does not generate unbalanced centrifugal force during rotation.

In the prior art, a dynamic balancing machine is usually used to dynamically balance the rotor. The operation process is as follows: firstly, the rotor is rotated at a low speed (that is, the speed range below the rigid critical speed of the rotor), and at low speed, the dynamic balancing machine is used to Carry out dynamic balancing operation on the rotor, and then carry out weighting or weight-removing balancing processing on the rotor to initially eliminate its unbalanced mass, and then repeat the above steps many times so that the rotor speed can break through the rigid critical speed and enter the super-rigid critical speed area. After the speed enters the ultra-rigid critical speed area, the rotor is dynamically balanced again by a dynamic balancing machine at high speed, and then the rotor is weighted or deweighted for balance processing. Moreover, in order to accurately remove the unbalanced mass, the above dynamic balancing operation usually needs to be repeated many times.

The working speed of the magnetic levitation molecular pump rotor is in the ultra-rigid critical speed area. What we pay attention to is the performance of the rotor at high speed, so the dynamic balance effect at low speed is relatively limited. Only when the rotor speed exceeds and leaves the rigid critical speed After a certain distance (entering the ultra-rigid critical speed region), the rotor will rotate approximately around its center of mass, and dynamic balancing is more accurate and better results can be obtained at this time. Since the rotor with unbalanced mass cannot be directly accelerated to the ultra-rigid critical speed, it cannot be dynamically balanced at high speed, so it must first be dynamically balanced at low speed to gradually increase the speed to the ultra-rigid critical speed area, and then Carrying out the dynamic balance at high speed again makes the steps of this dynamic balancing method cumbersome and inefficient.

Contents of the invention

The technical problem to be solved by the present invention is that the steps of the dynamic balancing method of the magnetic levitation molecular pump in the prior art are cumbersome and the efficiency is very low. Therefore, it provides a method that can directly perform dynamic balancing operation on the rotor of the magnetic levitation molecular pump at high speed, with simple steps and high efficiency. High dynamic balance method of magnetic levitation molecular pump.

In order to solve the problems of the technologies described above, the technical scheme adopted in the present invention is as follows:

A dynamic balancing method for a magnetic levitation molecular pump, comprising

①Start the motor of the magnetic levitation molecular pump to increase the speed, turn on the force control unbalanced vibration control module in the magnetic levitation molecular pump controller, and the magnetic levitation molecular pump controller controls the displacement detection device to collect the diameter of the magnetic levitation molecular pump rotor To detect the radial amplitude of the rotor, if under the control of the force control unbalanced vibration control module, the unbalanced mass on the rotor makes the maximum radial amplitude of the rotor during the speed-up process does not exceed 1/2 of the protection gap, then the force control unbalanced vibration control module can suppress the same-frequency vibration of the rotor, so that the rotor speed exceeds its rigid critical speed, and step ② is performed sequentially;

②The motor continues to accelerate, and the radial vibration of the rotor is detected by the displacement detection device. When the radial vibration amplitude of the rotor exceeds the preset non-rated speed amplitude, the acceleration of the motor is stopped to make the speed Stable at the rotational speed ω _i (i=0, 1, 2...); the magnetic levitation molecular pump controller controls the rotational speed detection device or the dynamic balancing machine to detect the rotational speed ω _i at this time; judge whether the rotational speed ω _i is smaller than the rotor Rated speed ω _E , if ω _i is less than ω _E , execute step ③ in sequence, otherwise execute step ⑤;

③ Under the control of the force control unbalanced vibration control module, use the dynamic balancing machine to perform a dynamic balancing operation where the rotor speed is not the rated speed, so that the rotor speed rises from zero to ω _i and the rotor speed is ω _i , the radial vibration amplitudes of the rotors are all less than the preset non-rated speed amplitudes, and then step ④ is performed in sequence;

④ Let i=i+1, repeat step ②;

⑤Under the control of the force control unbalanced vibration control module, use the dynamic balancing machine to carry out the dynamic balancing operation of the rotor speed at the rated speed, so that the rotor speed rises from zero to ω _E process, the radial vibration of the rotor The amplitudes are all less than the preset non-rated speed amplitude; and when the rotor speed is ω _E , the radial vibration amplitude of the rotor is less than the preset rated speed amplitude and the residual unbalanced mass of the rotor is less than the preset unbalanced mass , so far the whole dynamic balancing process is completed.

In the above dynamic balancing method, the step ③ is specifically:

1. Utilize the dynamic balancing machine to measure the vibration signal of the magnetic levitation molecular pump casing, and obtain the rotor speed signal synchronously. The dynamic balancing machine adopts the influence coefficient method or the modal balance method according to the measured magnetic levitation The vibration signal of the pump casing and the rotor speed signal are calculated to obtain the balance mass required by the rotor and the loading phase of the balance mass, and the motor is turned off to reduce the rotor speed to zero, and then step II is performed in sequence;

Ⅱ. Perform balancing processing on the rotor according to the calculated required balancing mass and the loading phase of the balancing mass, and then perform step III in sequence;

Ⅲ. Start the motor, open the force control unbalanced vibration control module, and detect the radial amplitude of the rotor by the displacement detection device (18), if under the control of the force control unbalanced vibration control module , the unbalanced mass on the rotor makes the maximum radial amplitude of the rotor not exceed 1/2 of the protection gap during the speed-up process, then the force control unbalanced vibration control module can suppress the same frequency of the rotor Vibration, so that the rotor speed exceeds its rigid critical speed, perform step IV in sequence;

Ⅳ. The motor continues to accelerate, and detects the radial amplitude of the rotor during the process of increasing the rotor speed to ω _i and when the rotor speed is ω _i , if the radial amplitude of the rotor is less than the preset non-rated speed amplitude, Then execute step ④; if it is found that the radial amplitude of the rotor is greater than or equal to the preset non-rated speed amplitude, stop the acceleration of the motor, and repeat the step I.

In the above dynamic balancing method, the step 5 is specifically:

A. If ω _i > ω _E , start the motor to decelerate and adjust the rotor speed to ω _E , otherwise keep the rotor speed at ω _E ;

B. Utilize the dynamic balancing machine to measure the vibration signal of the magnetic levitation molecular pump casing, and obtain the rotor speed signal synchronously. The dynamic balancing machine adopts the influence coefficient method or the modal balance method according to the measured magnetic levitation molecular The vibration signal of the pump casing and the rotor speed signal are calculated to obtain the balance mass required by the rotor and the loading phase of the balance mass, and the motor is turned off to reduce the rotor speed to zero, and then step C is performed in sequence;

C. Perform balancing processing on the rotor according to the calculated required balancing mass and the loading phase of the balancing mass, and then perform step D in sequence;

D. Start the motor, open the force control unbalanced vibration control module, detect the radial amplitude of the rotor by the displacement detection device, if under the control of the force control unbalanced vibration control module, the The unbalanced mass on the rotor makes the maximum radial amplitude of the rotor not exceed 1/2 of the protection gap during the speed-up process, then the force control unbalanced vibration control module can suppress the same-frequency vibration of the rotor, so that If the rotor speed exceeds its rigid critical speed, step E is performed in sequence;

E. The motor continues to accelerate, and detects the radial amplitude of the rotor in the process of increasing the rotor speed to _ωE , and if the radial amplitude of the rotor is smaller than the preset non-rated speed amplitude, then perform step F in sequence; If it is found that the radial amplitude of the rotor is greater than or equal to the preset non-rated rotational speed amplitude, then stop the motor from accelerating, and repeat step B;

F. Start the motor and continue to increase the speed to ω _E , stop the acceleration of the motor, stabilize the speed at the speed ω _E , and then perform step G in sequence;

G. Detect the radial amplitude of the rotor at this time,

a. If the radial amplitude of the rotor is less than the preset rated speed amplitude, then use the dynamic balancing machine to measure the vibration signal of the magnetic levitation molecular pump casing, and obtain the rotor speed signal synchronously. The dynamic balancing machine adopts the influence The coefficient method or the modal balance method calculates the required balance mass of the rotor and the loading phase of the balance mass according to the measured vibration signal of the magnetic levitation molecular pump casing and the rotor speed signal, and then closes the motor so that The rotor speed drops to zero;

ⅰ. If the residual unbalanced mass of the rotor is less than the preset unbalanced mass, the entire dynamic balancing process is completed;

iiii. Otherwise perform said step C;

b. If the radial amplitude of the rotor is greater than or equal to the preset rated rotational speed amplitude, repeat step B.

In the above dynamic balancing method, the value range of the preset non-rated speed amplitude is [20 μm, 40 μm], the value range of the preset rated speed amplitude is [0.05 μm, 0.1 μm], and the preset value is not The value range of the balance mass is [5mg, 12mg].

In the above dynamic balancing method, the preset non-rated speed amplitude is 40 μm, the preset rated speed amplitude is 0.1 μm, and the preset unbalanced mass is 10 mg.

In the above dynamic balancing method, before the step ①, there is also a step of obtaining the rotor rigidity critical speed and the rated speed ω _E according to the dynamic simulation calculation and experiment of the magnetic levitation molecular pump.

In the above dynamic balancing method, in the steps ③ and ⑤, the dynamic balancing machine measures the vibration signal of the magnetic levitation molecular pump casing through the vibration detection probe arranged on it, and the dynamic balancing machine measures the vibration signal of the magnetic levitation molecular pump casing through the vibration detection probe arranged on it. The speed probe measures the rotor speed signal.

The above technical solution of the present invention has the following advantages compared with the prior art:

① In the dynamic balancing method of the magnetic levitation molecular pump provided by the present invention, after starting the motor of the magnetic levitation molecular pump, the force control unbalanced vibration control module is turned on. If under the control of the force control unbalanced vibration control module, the unbalanced mass on the rotor Make the maximum radial amplitude of the rotor during the working process not exceed 1/2 of the protection gap (that is, the unbalanced mass of the rotor must be within a certain threshold range), then the force control unbalanced vibration control module can suppress the same frequency vibration of the rotor, The speed of the rotor can quickly exceed its rigid critical speed, and the rotor of the magnetic levitation molecular pump can be dynamically balanced at a higher speed, so that it is not necessary to do the rotor dynamic balance at a low speed, which simplifies the operation steps and can be quickly and efficiently The dynamic balancing operation greatly improves the efficiency of dynamic balancing.

② The dynamic balancing method of the magnetic levitation molecular pump provided by the present invention can use the general equipment dynamic balancing machine to complete the calculation of the balance mass required by the rotor and the loading phase of the balance mass, and is easy to operate.

③The dynamic balancing method of the magnetic levitation molecular pump provided by the present invention, when using the influence coefficient method or the modal balance method to obtain the balance mass and the loading phase of the balance mass required by the rotor, the force control is turned on again every time the speed is reduced, the unbalance vibration control The module makes the rotating speed of the rotor drop to zero smoothly to reduce the mechanical vibration caused by the unbalanced mass and protect the rotor components.

④The dynamic balancing method of the magnetic levitation molecular pump provided by the present invention adopts the force control unbalanced vibration control algorithm, and the force control unbalanced vibration control algorithm can be used in the case of a relatively large rotor vibration. By applying the same frequency excitation force as the original rotor The anti-phase control force can effectively reduce the displacement vibration of the rotor at the same frequency. Due to the principle of the force control unbalanced vibration control algorithm, the same frequency vibration of the rotor can be better transmitted to the casing of the molecular pump, which is beneficial to the use of dynamic balance. The instrument detects the rotor vibration signal.

⑤ In the dynamic balancing method of the magnetic levitation molecular pump provided by the present invention, the preset non-rated speed amplitude is 40 μm, which can meet the vibration requirements of the radial amplitude of the rotor at non-rated speed, so that the rotor can increase speed relatively steadily until reaching Rated speed. Among them, the preset rated speed amplitude is 0.1 μm, and the preset unbalanced mass is 10 mg. The above two numerical standards can ensure the smooth operation of the rotor at the rated speed and the stable operation of the magnetic levitation molecular pump.

Description of drawings

In order to make the content of the present invention more easily understood, the present invention will be described in further detail below according to specific embodiments of the present invention in conjunction with the accompanying drawings, wherein

Fig. 1 is the structural representation of magnetic levitation molecular pump in the present invention;

Fig. 2 is a principle diagram of the force control unbalanced vibration control algorithm in the present invention;

Fig. 3 is a flow chart of the dynamic balancing method in the present invention.

The reference signs in the figure are represented as: 1-impeller, 2-maglev molecular pump controller, 3-pump body, 4-first radial protection bearing, 5-first radial sensor, 6-first radial magnetic bearing , 7-rotor shaft, 8-motor, 9-second radial magnetic bearing, 10-second radial sensor, 11-second radial protection bearing, 12-axial protection bearing, 13-first axial magnetic Bearing, 14-thrust disc, 15-second axial magnetic bearing, 16-axial sensor, 17-connection terminal, 18-displacement detection device, 19-rotational speed detection device.

Detailed ways

As shown in Figure 1, it is a schematic structural diagram of the magnetic levitation molecular pump involved in the present invention. The magnetic levitation molecular pump in this embodiment is arranged vertically, and the magnetic levitation molecular pump includes a pump body 3 and a The rotor shafting and other structures that the magnetic levitation molecular pump in the prior art should have.

The rotor shaft system includes a rotor, a first radial magnetic bearing 6, a second radial magnetic bearing 9, a first axial magnetic bearing 13 and a second axial magnetic bearing 15; the rotor includes a rotor shaft 7, and the The impeller 1 fixed by the rotor shaft 7, and the assembly parts used to fix the impeller 1, such as screws, nuts, etc.

The axis of the rotor shaft 7 is arranged along the vertical direction, and the impeller 1 is fixedly arranged on the upper part of the rotor shaft 7 . The lower part of the rotor shaft 7 is provided with the first axial magnetic bearing 13, the second axial magnetic bearing 15, the thrust plate 14, the axial protection bearing 12 and the sensor for detecting the axial displacement signal of the rotor. Axial sensor 16. The first radial protection bearing 4, the first radial sensor 5, the first radial magnetic bearing 6, the motor 8, the second radial magnetic bearing 9, the second diameter To the sensor 10 and the second radial protection bearing 11 and other devices. The first radial protection bearing 4 and the second radial protection bearing 11 are coaxial and have the same radial size. The first radial magnetic bearing 6 includes a first radial magnetic bearing stator and a first radial magnetic bearing rotor, the first radial magnetic bearing stator is fixedly connected to the pump body 3, and the first radial magnetic bearing The magnetic bearing rotor is fixedly connected with the rotor shaft 7 ; the first radial sensor 5 is used to detect the radial displacement signal of the rotor at the first radial sensor 5 . The second radial magnetic bearing 9 includes a second radial magnetic bearing stator and a second radial magnetic bearing rotor, the second radial magnetic bearing stator is fixedly connected to the pump body 3, and the second radial magnetic bearing The magnetic bearing rotor is fixedly connected with the rotor shaft 7 ; the second radial sensor 10 is used to detect the radial displacement signal of the rotor at the second radial sensor 10 . The rotor shaft 7 is supported by the first radial magnetic bearing 6 , the second radial magnetic bearing 9 , the first axial magnetic bearing 13 and the second axial magnetic bearing 15 .

The control system of the magnetic suspension molecular pump comprises a displacement detection device 18, a rotational speed detection device 19 and a magnetic suspension molecular pump controller 2; the displacement detection device 18 is used to receive a displacement signal, and its signal input terminal is connected to the first radial sensor 5. The second radial sensor 10 is connected to the signal output end of the axial sensor 16, and the signal output end of the displacement detection device 18 is connected to the signal input end of the magnetic levitation molecular pump controller 2; The rotational speed detection device 19 is used to detect the rotor speed signal, and its signal input end is connected to the rotational speed detection sensor through the connection terminal 17 of the magnetic levitation molecular pump, and the signal output end of the rotational speed detection device 19 is connected to the magnetic levitation molecular pump controller 2 connected to the signal input terminal.

The magnetic levitation molecular pump controller 2 has built-in various control algorithm modules, and the magnetic levitation molecular pump controller 2 can call a suitable control algorithm for analysis and calculation according to the displacement signal obtained by the displacement detection device 18, and finally drive the corresponding magnetic levitation pump. Bearings (one or more of the first radial magnetic bearing 6, the second radial magnetic bearing 9, the first axial magnetic bearing 13 and the second axial magnetic bearing 15) output electromagnetic The force exerts control on the movement of the rotor. The magnetic levitation molecular pump controller 2 can also monitor the rotation of the rotor in real time according to the rotation speed signal obtained by the rotation speed detection device 19, and adjust the rotation speed of the rotor as required.

The maglev molecular pump controller 2 also has a built-in powerful control algorithm for unbalanced vibration, that is, an open-loop feedforward control algorithm. The force-controlled unbalanced vibration control algorithm can suppress the same-frequency vibration of the rotor by generating a control force that is opposite to the original same-frequency excitation force of the rotor, so that the rotor can rotate around its inertial axis, as shown in Figure 2 .

After the processing and assembly of the magnetic levitation molecular pump is completed, a dynamic balancing operation needs to be performed on the magnetic levitation molecular pump to remove the unbalanced mass of the rotor. In this embodiment, the rigid critical speed and rated speed ω _E of the rotor are known, as shown in Figure 3, the dynamic balancing method includes:

① Start the motor 8 to increase the speed, turn on the force control unbalanced vibration control module, and the magnetic levitation molecular pump controller 2 controls the displacement detection device 18 to collect the radial displacement signal of the magnetic levitation molecular pump rotor, Detect the radial amplitude of the rotor. In this embodiment, the displacement detection device 18 collects the radial amplitude of the rotor through the first radial sensor 5 and the second radial sensor 10 . If under the control of the force control unbalance vibration control module, the unbalanced mass on the rotor makes the maximum radial vibration amplitude of the rotor not exceed 1/2 of the protection gap during the speed-up process, then the force The unbalanced vibration control module can suppress the same-frequency vibration of the rotor, so that the rotor speed exceeds its rigid critical speed, and step ② is executed sequentially. If the maximum radial vibration amplitude of the rotor exceeds 1/2 of the radial protection gap, the traditional dynamic balancing method is adopted, and low-speed dynamic balancing is performed first to ensure that the rotor radial vibration does not exceed the radial vibration when the rotor speed exceeds the rigid critical speed. 1/2 of the protection gap; then after the rotor speed exceeds its rigid critical speed, step ② is performed sequentially.

② The motor 8 continues to accelerate, and the displacement detection device 18 detects the radial vibration of the rotor. When the radial vibration amplitude of the rotor exceeds the preset non-rated speed amplitude, stop the acceleration of the motor 8 , making the rotation speed stable at the rotation speed ω _i (i=0, 1, 2...). The value range of the preset non-rated rotational speed amplitude is [20 μm, 40 μm], and in this embodiment, the preset non-rated rotational speed amplitude is 40 μm. The magnetic levitation molecular pump controller 2 controls the rotational speed detection device 19 or the dynamic balancing machine to detect the rotor rotational speed ω _i at this time (the rotational speed detection device 19 collects the rotor rotational speed through a rotational speed detection sensor). Determine whether the rotational speed ω _i is less than the rotor rated rotational speed ω _E , if ω _i is less than ω _E , execute step ③ in sequence, otherwise execute step ⑤.

③ Under the control of the force control unbalanced vibration control module, use the dynamic balancing machine to perform a dynamic balancing operation where the rotor speed is not the rated speed, so that the rotor speed rises from zero to ω _i and the rotor speed is ω _i , the radial vibration amplitudes of the rotors are all smaller than the preset non-rated speed amplitude, that is, 40 m, and then step ④ is performed in sequence. Specific steps include:

1. Utilize the dynamic balancing machine to measure the vibration signal of the magnetic levitation molecular pump casing, and obtain the rotor speed signal synchronously, and the dynamic balancing machine measures the vibration of the magnetic levitation molecular pump casing through the vibration detection probe arranged on it The dynamic balancing machine measures the rotor speed signal through the speed probe provided on it. The dynamic balancing machine uses the influence coefficient method to calculate the balance mass required by the rotor and the loading phase of the balance mass according to the measured vibration signal of the magnetic levitation molecular pump casing and the rotor speed signal, and then closes the motor 8. Reduce the rotor speed to zero, and then execute step II in sequence.

In the process of implementing the influence coefficient method, the first balance plane and the second balance plane are preset, and both the first balance plane and the second balance plane are perpendicular to the axial direction of the rotor, and are set at positions away from the center of the rotor and close to both ends superior. Start the motor to increase the speed. When the rotor speed reaches the speed ω _i , stop the motor to accelerate, so that the speed is stable at ω _i . Record the initial unbalance vector V ₀ measured by the displacement sensors at the first balance plane and the second balance plane respectively. After the motor 8 is turned off and the rotor speed drops to zero, a test weight m1 is added to the first balance surface. Start the motor to increase the speed. When the rotor speed reaches the speed ω _i , stop the motor to accelerate, so that the speed is stable at ω _i . Record the initial unbalance vector V ₁ measured by the displacement sensors at the first balance plane and the second balance plane respectively. After the motor 8 is turned off and the rotor speed drops to zero, a test weight m2 is added on the second balance surface. Start the motor to increase the speed. When the rotor speed reaches the speed ω _i , stop the motor to accelerate, so that the speed is stable at ω _i . Record the initial unbalance vector V ₂ measured by the displacement sensors at the first balance plane and the second balance plane respectively. Turn off the motor 8, and the rotor speed drops to zero. Based on the above data, the influence coefficient method can be used to calculate the balance mass and loading phase required by each balance plane.

Ⅱ. Perform balancing processing on the rotor according to the calculated required balancing mass and the loading phase of the balancing mass, and then perform step III in sequence;

III. Start the motor 8, open the force control unbalanced vibration control module, and detect the radial amplitude of the rotor by the displacement detection device 18, if under the control of the force control unbalanced vibration control module, The unbalanced mass on the rotor makes the maximum radial amplitude of the rotor not exceed 1/2 of the protection gap during the speed-up process, then the force-controlled unbalanced vibration control module can suppress the same-frequency vibration of the rotor, Make the rotor speed exceed its rigid critical speed, and execute step IV in sequence.

Ⅳ. The motor 8 continues to accelerate, and detects the radial amplitude of the rotor during the process of increasing the rotor speed to ω _i and when the rotor speed is ω _i , if the radial amplitude of the rotor is less than the preset non-rated speed amplitude , then execute step ④; if it is found that the radial amplitude of the rotor is greater than or equal to the preset non-rated speed amplitude, then stop the acceleration of the motor 8, and repeat the step I.

④ Let i=i+1, repeat step ②.

⑤Under the control of the force control unbalanced vibration control module, use the dynamic balancing machine to carry out the dynamic balancing operation of the rotor speed at the rated speed, so that the rotor speed rises from zero to ω _E process, the radial vibration of the rotor The amplitudes are all less than the preset non-rated speed amplitude; and when the rotor speed is ω _E , the radial vibration amplitude of the rotor is less than the preset rated speed amplitude and the residual unbalanced mass of the rotor is less than the preset unbalanced mass , so far the whole dynamic balancing process is completed. The value range of the preset rated rotational speed amplitude is [0.05 μm, 0.1 μm], and the value range of the preset unbalanced mass is [5 mg, 12 mg]. In this embodiment, the preset rated The rotational speed amplitude is 0.1 μm, and the preset unbalanced mass is 10 mg. Specific steps include:

A. If ω _i >ω _E , start the motor 8 to decelerate and adjust the rotor speed to ω _E , otherwise keep the rotor speed at ω _E .

B. Utilize the dynamic balancing machine to measure the vibration signal of the magnetic levitation molecular pump casing, and obtain the rotor speed signal synchronously, and the dynamic balancing machine measures the vibration of the magnetic levitation molecular pump casing through the vibration detection probe arranged on it The dynamic balancing machine measures the rotor speed signal through the speed probe provided on it. The dynamic balancing machine uses the influence coefficient method to calculate the balance mass required by the rotor and the loading phase of the balance mass according to the measured vibration signal of the magnetic levitation molecular pump casing and the rotor speed signal, and then closes the motor 8. Reduce the rotor speed to zero, and then perform step C in sequence.

In the process of implementing the influence coefficient method, the first balance plane and the second balance plane are preset, and both the first balance plane and the second balance plane are perpendicular to the axial direction of the rotor, and are set at positions away from the center of the rotor and close to both ends superior. Start the motor and increase the speed. When the rotor speed reaches the rated speed ω _E , stop the motor to accelerate, so that the speed is stable at ω _E . Record the initial unbalance vector V' ₀ measured by the displacement sensors at the first balance plane and the second balance plane respectively. After the motor 8 is turned off and the rotor speed drops to zero, a test weight m' ₁ is added to the first balance surface. Start the motor to accelerate, when the rotor speed reaches the rated speed ω _E , stop the motor to accelerate, so that the speed is stable at ω _E . Record the initial unbalance vector V' ₁ measured by the displacement sensors at the first balance plane and the second balance plane respectively. After the motor 8 is turned off and the rotor speed drops to zero, a test weight m' ₂ is added on the second balance plane. Start the motor to accelerate, when the rotor speed reaches the rated speed ω _E , stop the motor to accelerate, so that the speed is stable at ω _E . Record the initial unbalance vector V′ ₂ measured by the displacement sensors at the first balance plane and the second balance plane respectively. Turn off the motor 8, and the rotor speed drops to zero. Based on the above data, the influence coefficient method can be used to calculate the balance mass and loading phase required by each balance plane.

C. Perform balancing processing on the rotor according to the calculated required balancing mass and the loading phase of the balancing mass, and then perform step D in sequence.

D. Start the motor 8, open the force control unbalance vibration control module, detect the radial amplitude of the rotor by the displacement detection device 18, if under the control of the force control unbalance vibration control module, The unbalanced mass on the rotor makes the maximum radial amplitude of the rotor not exceed 1/2 of the protection gap during the speed-up process, then the force-controlled unbalanced vibration control module can suppress the same-frequency vibration of the rotor, Make the rotor speed exceed its rigid critical speed, and execute step E in sequence.

E. The motor 8 continues to accelerate, and detects the radial amplitude of the rotor during the speed-up of the rotor speed to ω _E. If the radial amplitude of the rotor is less than the preset non-rated speed amplitude, step F is performed in sequence ; If it is found that the radial amplitude of the rotor is greater than or equal to the preset non-rated rotational speed amplitude, stop the acceleration of the motor 8 and repeat the step B.

F. Start the motor 8 and continue to increase the speed to ω _E , stop the motor 8 to accelerate, and stabilize the rotation speed at the rotation speed ω _E , and then execute step G in sequence.

G. Detect the radial amplitude of the rotor at this time,

a. If the radial amplitude of the rotor is less than the preset rated speed amplitude, then use the dynamic balancing machine to measure the vibration signal of the magnetic levitation molecular pump casing, and obtain the rotor speed signal synchronously. The dynamic balancing machine adopts the influence The coefficient method calculates the required balance mass of the rotor and the loading phase of the balance mass according to the measured vibration signal of the magnetic levitation molecular pump casing and the rotor speed signal, and closes the motor 8 to reduce the rotor speed to zero;

i. If the residual unbalanced mass of the rotor is less than the preset unbalanced mass, the entire dynamic balancing process is completed;

ii. Otherwise perform said step C;

b. If the radial amplitude of the rotor is greater than or equal to the preset rated rotational speed amplitude, repeat step B.

In other embodiments, before the step ①, it also includes the step of obtaining the rotor rigidity critical speed and the rated speed ω _E according to the dynamic simulation calculation and experiment of the magnetic levitation molecular pump, and the dynamic simulation calculation and experiment adopt the current There are computational and experimental methods known in the art.

In other embodiments, the dynamic balancing machine may also adopt a modal balance method in addition to the influence coefficient method.

In other embodiments, according to different situations, the preset non-rated speed amplitude can also be selected as 20 μm, 25 μm, 30 μm or 35 μm, etc., and the preset rated speed amplitude can also be selected as 0.05 μm, 0.07 μm or 0.09 μm etc., the preset unbalanced mass can also be selected as 5 mg, 8 mg or 12 mg, etc., which can also achieve the purpose of the present invention.

Apparently, the above-mentioned embodiments are only examples for clear description, rather than limiting the implementation. For those of ordinary skill in the art, other changes or changes in different forms can be made on the basis of the above description. It is not necessary and impossible to exhaustively list all the implementation manners here. And the obvious changes or changes derived therefrom are still within the scope of protection of the present invention.

Claims (7)

1. a dynamic balance method of magnetic molecular pump, is characterized in that: comprise

1. the motor (8) that starts described maglev molecular pump starts raising speed, open the power control unbalance vibration control module in maglev molecular pump controller (2), gathered the radial displacement signal of described maglev molecular pump rotor by described maglev molecular pump controller (2) control displacement detector (18), detect the radially amplitude of described rotor, if under the control of described power control unbalance vibration control module, described epitrochanterian unbalance mass, makes the maximum radial amplitude of described rotor in boosting velocity procedure be no more than 1/2 of protection gap, so described power control unbalance vibration control module can suppress the once per revolution vibration of described rotor, make rotor speed exceed its rigidity critical speed of rotation, order execution step 2.,

2. described motor (8) continues to accelerate, detected the radial vibration situation of described rotor by described displacement detector (18), in the time that the amplitude of radial vibration of described rotor exceedes default non-rated speed amplitude, stop described motor (8) and accelerate, make stabilization of speed in this rotational speed omega _i(i=0,1,2 ...) locate; Control dynamic balancing machine by described maglev molecular pump controller (2) and detect rotational speed omega now _i; Judge rotational speed omega _iwhether be less than rotor rated speed ω _eif, ω _ibe less than ω _eperform step 3. in order, otherwise execution step 5.;

3. under the control of described power control unbalance vibration control module, utilize described dynamic balancing machine to carry out the dynamic balancing operation that rotor speed is non-rated speed, make rotor speed rise to ω from zero _iin process and rotor speed be ω _itime, the amplitude of radial vibration of described rotor is all less than default non-rated speed amplitude, performs step 4. in order afterwards;

4. make i=i+1, repeating step 2.;

5. under the control of described power control unbalance vibration control module, utilize described dynamic balancing machine to carry out rotor speed for rated speed dynamic balancing operation, make rotor speed rise to ω from zero _ein process, the amplitude of radial vibration of described rotor is all less than default non-rated speed amplitude; And making rotor speed is ω _etime, the unbalance mass, that the amplitude of radial vibration of described rotor is less than default rated speed amplitude and described rotor remnants is less than default unbalance mass,, and so far whole dynamic balancing process completes.

2. dynamic balance method according to claim 1, is characterized in that: 3. described step is specially:

I. utilize described dynamic balancing machine to measure the oscillating signal of described maglev molecular pump casing, and synchronously obtain rotor speed signal, described dynamic balancing machine adopts influence coefficient method or modal balance method to draw balancing mass that described rotor is required and the loading phase place of balancing mass according to the oscillating signal of measured described maglev molecular pump casing and rotor speed calculated signals, close described motor (8), make rotor speed drop to zero, perform step in order afterwards II;

II. according to calculating the required balance quality of acquisition and the loading phase place of balancing mass, to described balancing rotor processing, perform step in order afterwards III;

III. start described motor (8), open described power control unbalance vibration control module, detected the radially amplitude of described rotor by described displacement detector (18), if under the control of described power control unbalance vibration control module, described epitrochanterian unbalance mass, makes the maximum radial amplitude of described rotor in boosting velocity procedure be no more than 1/2 of protection gap, so described power control unbalance vibration control module can suppress the once per revolution vibration of described rotor, make rotor speed exceed its rigidity critical speed of rotation, perform step in order IV;

IV. described motor (8) continues to accelerate, and detection rotor rotating speed raising speed is to ω _iin process and rotor speed be ω _ithe radially amplitude of Shi Suoshu rotor, if the radially amplitude of described rotor is all less than default non-rated speed amplitude, execution step is 4.; If find that the radially amplitude of described rotor is more than or equal to default non-rated speed amplitude, stop described motor (8) and accelerate, repeat described step I.

3. dynamic balance method according to claim 2, is characterized in that: 5. described step is specially:

If A. ω _i> ω _estarting described motor (8) slows down rotor speed is adjusted into ω _e, otherwise rotor speed is remained on to ω _e;

B. utilize described dynamic balancing machine to measure the oscillating signal of described maglev molecular pump casing; and synchronously obtain rotor speed signal; described dynamic balancing machine adopts influence coefficient method or modal balance method to draw balancing mass that described rotor is required and the loading phase place of balancing mass according to the oscillating signal of measured described maglev molecular pump casing and rotor speed calculated signals; close described motor (8); make rotor speed drop to zero, perform step in order afterwards C;

C. according to calculating the required balance quality of acquisition and the loading phase place of balancing mass, to described balancing rotor processing, perform step in order afterwards D;

D. start described motor (8), open described power control unbalance vibration control module, detected the radially amplitude of described rotor by described displacement detector (18), if under the control of described power control unbalance vibration control module, described epitrochanterian unbalance mass, makes the maximum radial amplitude of described rotor in boosting velocity procedure be no more than 1/2 of protection gap, so described power control unbalance vibration control module can suppress the once per revolution vibration of described rotor, make rotor speed exceed its rigidity critical speed of rotation, perform step in order E;

E. described motor (8) continues to accelerate, and detection rotor rotating speed raising speed is to ω _ethe radially amplitude of rotor described in process, if the radially amplitude of described rotor is all less than default non-rated speed amplitude, performs step F in order; If find that the radially amplitude of described rotor is more than or equal to default non-rated speed amplitude, stop described motor (8) and accelerate, repeat described step B;

F. start described motor (8) and continue raising speed to ω _e, stop described motor (8) and accelerate, make stabilization of speed in this rotational speed omega _eplace, performs step G afterwards in order;

G. detect the now radially amplitude of described rotor,

If a. the radially amplitude of described rotor is less than default rated speed amplitude, utilize described dynamic balancing machine to measure the oscillating signal of described maglev molecular pump casing, and synchronously obtain rotor speed signal, described dynamic balancing machine adopts influence coefficient method or modal balance method to draw balancing mass that described rotor is required and the loading phase place of balancing mass according to the oscillating signal of measured described maglev molecular pump casing and rotor speed calculated signals, close described motor (8), make rotor speed drop to zero;

I. if the unbalance mass, of described rotor remnants is less than default unbalance mass,, and whole dynamic balancing process completes;

II. otherwise carry out described step C;

If b. the radially amplitude of described rotor is more than or equal to default rated speed amplitude, repeat described step B.

4. according to the arbitrary described dynamic balance method of claim 1-3, it is characterized in that: the span of described default non-rated speed amplitude is [20 μ m, 40 μ m], the span of described default rated speed amplitude is [0.05 μ m, 0.1 μ m], the span of described default unbalance mass, is [5mg, 12mg].

5. dynamic balance method according to claim 4, is characterized in that: described default non-rated speed amplitude is 40 μ m, and described default rated speed amplitude is 0.1 μ m, and described default unbalance mass, is 10mg.

6. dynamic balance method according to claim 5, is characterized in that: 1. described step also comprises according to the dynamics simulation of described maglev molecular pump and experiment and obtain rotor rigidity critical speed of rotation and rated speed ω before _estep.

7. dynamic balance method according to claim 6, it is characterized in that: in described step 3. and 5., described dynamic balancing machine is by the oscillating signal of maglev molecular pump casing described in the vibration detection probe measurement arranging on it, and described dynamic balancing machine is measured rotor speed signal by the rotational speed probe arranging on it.

Images