A method and device for actively controlling vibration of a turbocharger rotor

Abstract

The present invention relates to a method and device for actively controlling the vibration of a turbocharger rotor, comprising: establishing a finite element dynamics model of a turbocharger rotor system including an outer oil film gap of a floating ring bearing; performing full speed tests under different outer oil film gaps to obtain a time domain response vibration displacement full-frequency amplitude diagram and a frequency domain response vibration displacement waterfall diagram under each outer oil film gap; dividing the time domain response vibration displacement full-frequency amplitude diagram and the frequency domain response vibration displacement waterfall diagram under each outer oil film gap into speed sections; in the same speed section divided in all the time domain response vibration displacement full-frequency amplitude diagrams and the frequency domain response vibration displacement waterfall diagrams, applying the principle that the full-frequency vibration displacement amplitude is minimum and the root mean square of each divided frequency amplitude is minimum, determining the optimal outer oil film gap value corresponding to each speed section; and performing active vibration control of the turbocharger rotor according to the optimal outer oil film gap value corresponding to each speed section.

Description

Technical Field

[0001] The invention relates to the field of turbocharger dynamics and vibration control, and in particular to a method and device for actively controlling vibration of a turbocharger rotor. Background Art

[0002] Affected by the variable operating conditions of the engine, the turbocharger needs to start and stop frequently, has a wide operating speed range, and changes speed quickly. For example, a certain type of gasoline engine turbocharger sometimes needs to accelerate from 0 to 240krpm within 3 seconds. Due to the nonlinear oil film characteristics of the floating ring bearing, the rotor will cause increased vibration due to excitations such as imbalance and friction during operation, which seriously affects the NVH quality of the product and may even cause destructive accidents. At present, turbochargers often use oil temperature and oil pressure to control rotor vibration, but the adjustment capacity is limited and the hysteresis time is much greater than 10 milliseconds, which makes it difficult to meet the needs of fast and accurate control. Therefore, it is urgent to combine advanced control technology to quickly and accurately control the vibration of the turbocharger rotor system.

[0003] At present, electrorheological fluid, electromagnetic bearings, magnetorheological fluid, variable parameter squeeze film damper and other technologies are mainly used at home and abroad to study the vibration control of rotor systems. In terms of electrorheological fluid vibration suppression, the researchers used voltage-regulated electrorheological fluid squeeze film dampers to provide damping for the first two vibration modes of the three-disk rotor system, and used multi-disk friction and multi-layer squeeze electrorheological material dampers to control the vibration of the single-disk cantilever rotor system using a switch control method. However, the working voltage of the electrorheological fluid is as high as several thousand volts, which is difficult to apply to turbochargers. In terms of electromagnetic bearing vibration suppression, the researchers analyzed the vibration characteristics and control methods of the electromagnetic bearing rotor, and used electromagnetic dampers to eliminate the rotor imbalance response online. However, the power-to-weight ratio of electromagnetic bearings and dampers is relatively small, and the structure is complex, which limits their application in turbochargers. In terms of magnetorheological fluid vibration suppression, the researchers studied the performance of magnetorheological dampers and vibration control methods, proposed a shear-type magnetorheological damper to control the imbalance response of the cantilever flexible rotor system, designed squeezed magnetorheological material dampers of various structural forms for single-disk rotor system vibration control, and conducted active control experimental research on the vibration of a single-span rotor containing a magnetorheological fluid damper. The working voltage of magnetorheological fluid is 2-25 volts, which overcomes the disadvantage of high working voltage of electrorheological fluid, but there is still a practical problem that the device is too large and difficult to apply to turbochargers; in terms of vibration suppression of variable parameter squeeze film damper, researchers use open-loop control of variable parameter squeeze film damper with squirrel cage elastic support to suppress the resonance amplitude of the first two critical speeds of a single disc rotor, or use segmented control of variable parameter squeeze film damper to control the vibration of flexible rotor over each critical speed, but there is no squeeze film damper in the turbocharger. If a variable parameter squeeze film damper is introduced, the original rotor system structure and characteristics will be greatly changed. The above research provides a reference for the vibration control of the turbocharger rotor system, but in view of the above reasons, it is still necessary to find a suitable vibration control method and control device for it according to the actual situation of the turbocharger. This patent proposes a method for active control of fast-changing vibration of turbocharger rotor and a control device based on piezoelectric ceramic drive to adjust the outer oil film gap of floating ring bearing to achieve rapid and accurate control of the vibration of the rotor system. Summary of the invention

[0004] The purpose of the present invention is to provide a method and device for actively controlling the vibration of a turbocharger rotor. By obtaining the optimal outer oil film clearance value corresponding to each speed section, the optimal outer oil film clearance corresponding to different speeds during the actual operation of the turbocharger rotor system can be quickly determined and the current outer oil film clearance can be adjusted to the optimal value, thereby achieving rapid and accurate control of the vibration of the turbocharger rotor system.

[0005] To achieve the above object, the present invention provides the following solutions:

[0006] A method for actively controlling vibration of a turbocharger rotor, the method comprising:

[0007] Establish a finite element dynamics model of the turbocharger rotor system with the outer oil film clearance of the floating ring bearing;

[0008] According to the finite element dynamics model of the turbocharger rotor system, a full speed range speed increase simulation test is performed under the conditions of different external oil film gaps to obtain a time domain response vibration displacement full-frequency amplitude diagram and a frequency domain response vibration displacement waterfall diagram under each external oil film gap;

[0009] Dividing the time domain response vibration displacement full-frequency amplitude diagram and the frequency domain response vibration displacement waterfall diagram under each of the outer oil film gaps into speed segments;

[0010] In the same speed segment divided in all the time domain response vibration displacement full-frequency amplitude diagrams and the frequency domain response vibration displacement waterfall diagrams, the principle of minimum full-frequency vibration displacement amplitude and minimum root mean square amplitude of each sub-frequency is applied to determine the optimal outer oil film clearance value corresponding to each speed segment; and according to the optimal outer oil film clearance value corresponding to each speed segment, a turbocharger rotor vibration active control strategy based on the sub-speed segment is constructed;

[0011] Active control of the turbocharger rotor vibration is performed according to the turbocharger rotor vibration active control strategy based on the speed-specific segment.

[0012] Optionally, the dynamic expression of the finite element dynamic model of the turbocharger rotor system is:

[0013]

[0014] Among them, M1 is the mass matrix of the rotor system, C1 is the damping matrix, K1 is the stiffness matrix, ρ is the vibration displacement, is the vibration acceleration; is the vibration velocity; u is the external excitation force.

[0015] Optionally, according to the finite element dynamics model of the turbocharger rotor system, a full speed range speed increase simulation test is performed under different external oil film gaps to obtain a time domain response vibration displacement full-frequency amplitude diagram and a frequency domain response vibration displacement waterfall diagram under each external oil film gap, specifically including:

[0016] Under each of the outer oil film gaps, the finite element dynamics model of the turbocharger rotor system is analyzed by using the Newmark direct integration method, and based on the assumption of the mean long acceleration, the vibration displacement of the turbocharger rotor at different times under different speeds is obtained;

[0017] The time domain response vibration displacement full frequency amplitude diagram is constructed with time as the abscissa and the vibration displacement as the ordinate;

[0018] Performing Fourier transform on the vibration displacement to obtain frequency domain amplitudes of the vibration displacement at different rotation speeds;

[0019] The frequency domain response vibration displacement waterfall diagram is constructed with frequency as the horizontal coordinate, the frequency domain amplitude as the vertical coordinate, and the rotation speed as the vertical coordinate.

[0020] Optionally, dividing the time domain response vibration displacement full-band amplitude diagram and the frequency domain response vibration displacement waterfall diagram under each of the outer oil film gaps into speed segments specifically includes:

[0021] According to the speed range in which oil film vortex appears in the oil film frequency division vibration inside the floating ring bearing, the speed range in which oil film oscillation appears, and the speed range in which the outer film frequency division vibration of the floating ring bearing appears, the time domain response vibration displacement full-frequency amplitude diagram and the frequency domain response vibration displacement waterfall diagram under each outer oil film gap are divided into speed segments.

[0022] Optionally, after establishing the finite element dynamics model of the turbocharger rotor system including the outer oil film clearance of the floating ring bearing, the method further includes:

[0023] Constructing a simulation model of the turbocharger rotor system finite element dynamics model;

[0024] The simulation model is simulated to obtain a Bode diagram of the rotor system during the speed increase process;

[0025] Determine a journal speed simulation value corresponding to the critical speed of the rotor system according to the Bode diagram;

[0026] Performing actual vibration testing on the finite element dynamics model of the turbocharger rotor system to obtain a measured value of the journal speed corresponding to the critical speed of the rotor system;

[0027] Determine whether the error between the simulated value of the journal speed and the measured value of the journal speed is less than a preset value;

[0028] If so, the finite element dynamics model of the turbocharger rotor system is verified.

[0029] Optionally, the active control of the turbocharger rotor vibration according to the turbocharger rotor vibration active control strategy based on the speed segment specifically includes:

[0030] According to the turbocharger rotor vibration active control strategy based on the speed segment, the optimal outer oil film clearance value of the actual turbocharger rotor system at the current speed is obtained;

[0031] adjusting the outer oil film value of the turbocharger rotor system to the optimal outer oil film value to obtain the vibration displacement of the turbocharger rotor system under optimal conditions;

[0032] The outer oil film value of the turbocharger rotor system is adjusted to the optimal outer oil film value plus a second preset value, to obtain the vibration displacement of the turbocharger rotor system after the oil film value is increased;

[0033] The outer oil film value of the turbocharger rotor system is adjusted to the optimal outer oil film value minus a third preset value, to obtain a vibration displacement of the turbocharger rotor system after the oil film value is reduced;

[0034] Compare the vibration displacement under the optimal condition, the vibration displacement after the oil film value is increased, and the vibration displacement after the oil film value is decreased to obtain the outer oil film value corresponding to the minimum value of the vibration displacement value;

[0035] Active vibration control of the turbocharger rotor is performed according to the outer oil film value corresponding to the minimum vibration displacement value.

[0036] A device for actively controlling the vibration of a turbocharger rotor, the device comprising: a retractable piezoelectric ceramic mechanism, a controller connected to the retractable piezoelectric ceramic mechanism by wire, a bearing seat, a fixed bearing bush fixedly connected to the bearing seat, a movable bearing bush slidably connected to the bearing seat, a floating ring arranged in an area surrounded by the fixed bearing bush and the movable bearing bush, and a journal arranged in the floating ring;

[0037] A gap is provided between the fixed bearing bush and the movable bearing bush;

[0038] The controller is used to execute a method for actively controlling vibration of a turbocharger rotor;

[0039] The retractable piezoelectric ceramic mechanism comprises a retractable part and a fixed part; the fixed part is fixedly connected to the bearing seat;

[0040] The telescopic portion is connected to the movable bearing bush;

[0041] The retractable piezoelectric ceramic mechanism is used to drive the movable bearing to move in a direction close to or away from the fixed bearing under a driving voltage corresponding to the outer oil film clearance value output by the controller.

[0042] According to the specific embodiments provided by the present invention, the present invention discloses the following technical effects:

[0043] The present invention relates to a method and device for actively controlling the vibration of a turbocharger rotor, comprising: establishing a finite element dynamics model of a turbocharger rotor system including an outer oil film gap of a floating ring bearing; performing full speed tests under different outer oil film gaps to obtain a time domain response vibration displacement full-frequency amplitude diagram and a frequency domain response vibration displacement waterfall diagram under each outer oil film gap; dividing the time domain response vibration displacement full-frequency amplitude diagram and the frequency domain response vibration displacement waterfall diagram under each outer oil film gap into speed sections; in the same speed section divided in all the time domain response vibration displacement full-frequency amplitude diagrams and the frequency domain response vibration displacement waterfall diagrams, applying the principle that the full-frequency vibration displacement amplitude is minimum and the root mean square of each divided frequency amplitude is minimum, determining the optimal outer oil film gap value corresponding to each speed section; and performing active vibration control of the turbocharger rotor according to the optimal outer oil film gap value corresponding to each speed section. By obtaining the optimal outer oil film clearance value corresponding to each speed section, the optimal outer oil film clearance corresponding to different speeds during the actual operation of the turbocharger rotor system can be quickly determined and the current outer oil film clearance can be adjusted to the optimal value, thereby achieving rapid and accurate vibration control of the turbocharger rotor system, ensuring that the vibration displacement amplitude of the turbocharger rotor system is minimized, and improving the performance of the turbocharger rotor system. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0045] Figure 1 A flow chart of a method for actively controlling vibration of a turbocharger rotor provided in Example 1 of the present invention;

[0046] Figure 2 The finite element dynamics model of the turbocharger rotor system provided in Example 1 of the present invention;

[0047] Figure 3 The Bode diagram calculated based on the finite element dynamics model of the turbocharger rotor system provided in Example 1 of the present invention;

[0048] Figure 4 A full-frequency amplitude diagram of the time-domain response vibration displacement under the outer oil film gap provided in Example 1 of the present invention;

[0049] Figure 5 A frequency domain response vibration displacement waterfall diagram under the outer oil film gap provided in Example 1 of the present invention;

[0050] Figure 6A basic principle diagram of a turbocharger rotor system vibration control method provided in Example 1 of the present invention;

[0051] Figure 7 This is a structural diagram of a turbocharger rotor vibration active control device provided in Example 2 of the present invention.

[0052] Reference numerals:

[0053] 7-1: retractable piezoelectric ceramic mechanism; 7-2: bearing seat; 7-3: fixed bearing shell; 7-4: movable bearing shell; 7-5: floating ring; 7-6: shaft neck; 7-7: wire. DETAILED DESCRIPTION

[0054] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0055] The object of the present invention is to provide a method and device for actively controlling the vibration of a turbocharger rotor. By obtaining the optimal outer oil film clearance value corresponding to each speed section, the optimal outer oil film clearance corresponding to different speeds during the actual operation of the turbocharger rotor system can be quickly determined and the current outer oil film clearance can be adjusted to the optimal value, thereby achieving rapid and accurate vibration control of the turbocharger rotor system, ensuring that the vibration displacement amplitude of the turbocharger rotor system is minimized, and improving the performance of the turbocharger rotor system.

[0056] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0057] Example 1

[0058] like Figure 1 As shown, this embodiment provides a method for actively controlling vibration of a turbocharger rotor, the method comprising:

[0059] S1: Establish a finite element dynamics model of a turbocharger rotor system containing an outer oil film gap of a floating ring bearing; Figure 2 As shown, in the figure, A represents the turbine; B represents the shaft; C represents the compressor wheel; and D represents the locking nut.

[0060] The dynamic expression of the finite element dynamic model of the turbocharger rotor system is:

[0061]

[0062] Among them, M1 is the mass matrix of the rotor system, C1 is the damping matrix, K1 is the stiffness matrix, ρ is the vibration displacement, is the vibration acceleration; is the vibration velocity; u is the external excitation force.

[0063] Considering the accuracy of the construction of the finite element dynamics model of the turbocharger rotor system, it is necessary to verify the model after the model construction is completed. Therefore, after the finite element dynamics model of the turbocharger rotor system containing the outer oil film clearance of the floating ring bearing is established, the accuracy of the parameter selection in the model is verified through the critical speed experiment. The specific verification process is as follows:

[0064] Constructing a simulation model of the turbocharger rotor system finite element dynamics model;

[0065] The simulation model is simulated to obtain the Bode diagram of the rotor system during the speed increase process, such as Figure 3 shown.

[0066] Determine a journal speed simulation value corresponding to the critical speed of the rotor system according to the Bode diagram;

[0067] Performing actual vibration testing on the finite element dynamics model of the turbocharger rotor system to obtain a measured value of the journal speed corresponding to the critical speed of the rotor system;

[0068] Determine whether the error between the simulated value of the journal speed and the measured value of the journal speed is less than a preset value;

[0069] If so, the finite element dynamics model of the turbocharger rotor system is verified.

[0070] S2: Based on the finite element dynamics model of the turbocharger rotor system, a full speed test is performed under different external oil film gaps to obtain a time domain response vibration displacement full-frequency amplitude diagram and a frequency domain response vibration displacement waterfall diagram under each external oil film gap; Figure 4 and 5 shown.

[0071] Step S2 specifically includes:

[0072] (1) Under each of the external oil film gaps, the finite element dynamics model of the turbocharger rotor system is analyzed using the Newmark direct integration method, and based on the assumption of average constant acceleration, the vibration displacement of the turbocharger rotor at different speeds and at different times is obtained;

[0073] The Newmark direct integration method is used to analyze and calculate the model. Based on the assumption of average constant acceleration, the vibration displacement calculation formula is as follows:

[0074]

[0075]

[0076] in, They are t i Vibration acceleration, vibration velocity, vibration displacement at the moment; They are t i+1 Vibration acceleration, vibration velocity, vibration displacement at time t i+1 =t i +dt, dt is the time step, i=0,1,2,···.

[0077] The time domain response vibration displacement ρ of the rotor system in the full speed range under the external oil film gap of various typical floating ring bearings is obtained. i , where i=0,1,2,···.

[0078] (2) With time as the horizontal coordinate and the vibration displacement as the vertical coordinate, construct the time domain response vibration displacement full-frequency amplitude diagram, such as Figure 4 ;

[0079] (3) performing Fourier transform on the vibration displacement to obtain frequency domain amplitudes of the vibration displacement at different rotation speeds;

[0080] The specific formula of Fourier transform is as follows:

[0081]

[0082] X(k) is the time domain vibration displacement ρ i The frequency domain signal obtained by Fourier transform, X(k) is a complex number, and its modulus is the frequency domain amplitude. k is the frequency, and the frequency domain amplitude diagram corresponding to different frequencies at each speed of the rotor system is obtained. Then, the frequency domain amplitude diagrams at multiple adjacent speeds are arranged in order from low to high according to the speed of the rotor system to obtain the frequency domain response vibration displacement waterfall diagram.

[0083] (4) The frequency domain response vibration displacement waterfall diagram is constructed with frequency as the horizontal coordinate, the frequency domain amplitude as the vertical coordinate, and the rotation speed as the vertical coordinate, such as Figure 5 .

[0084] S3: Divide the time domain response vibration displacement full-band amplitude diagram and the frequency domain response vibration displacement waterfall diagram under each of the outer oil film gaps into speed segments.

[0085] The speed of the turbocharger rotor system changes quickly. Taking a certain type of gasoline engine turbocharger as an example, it is sometimes necessary to accelerate from 0 to 240krpm within 3 seconds. When adjusting the bearing outer oil film gap in the speed interval to control the vibration of the rotor system, the running time of each speed interval is relatively short. If there are too many types of speed interval subdivisions, the running time of each speed interval will be very short, even close to the hysteresis time (10 milliseconds) of the piezoelectric ceramic mechanism, which seriously affects the control effect. Therefore, in this embodiment, the full speed interval is divided into three speed sections. The low speed section corresponds to the speed section where the oil film vortex often appears in the internal oil film frequency division vibration, the medium speed section corresponds to the speed section where the oil film oscillation often appears in the internal oil film frequency division vibration, and the high speed section corresponds to the speed section where the outer oil film frequency division vibration often appears. That is, step S3 specifically includes:

[0086] According to the speed range in which oil film vortex appears in the oil film frequency division vibration inside the floating ring bearing, the speed range in which oil film oscillation appears, and the speed range in which the outer film frequency division vibration of the floating ring bearing appears, the time domain response vibration displacement full-frequency amplitude diagram and the frequency domain response vibration displacement waterfall diagram under each outer oil film gap are divided into speed segments.

[0087] S4: In the same speed section divided in all the time domain response vibration displacement full-band amplitude diagrams and the frequency domain response vibration displacement waterfall diagrams, the principle of minimizing the full-band vibration displacement amplitude and minimizing the root mean square amplitude of each divided frequency is applied to determine the optimal external oil film clearance value corresponding to each speed section.

[0088] According to the vibration displacement waterfall diagram, the full speed range is divided into three speed sections: low, medium and high. According to the principle that the through-frequency vibration displacement amplitude is the smallest and the root mean square amplitude of each sub-frequency is the smallest, the optimal outer oil film clearance values ​​corresponding to the low, medium and high speed sections are determined, and the mapping relationship between the optimal outer oil film clearance and the vibration response in each speed section is obtained. The role of the mapping relationship between the optimal outer oil film clearance and the vibration response in each speed section is that when the speed is determined, the optimal outer oil film clearance can be quickly obtained according to the mapping relationship. Under this optimal outer oil film clearance, the vibration displacement of the turbocharger rotor system is the smallest relative to other outer oil film clearances. This lays the foundation for the next step of controlling the vibration of the turbocharger rotor system by adjusting the outer oil film clearance, that is, obtaining the rotor system vibration control strategy in the next step.

[0089] S5: constructing a turbocharger rotor vibration active control strategy based on speed segments according to the optimal outer oil film clearance value corresponding to each speed segment.

[0090] S6: Actively controlling the turbocharger rotor vibration according to the turbocharger rotor vibration active control strategy based on the speed-specific segments.

[0091] The vibration of the rotor system is tested and transformed by sensors. A speed sensor and a displacement sensor are installed on the housing of the turbocharger, and the speed and vibration displacement of the turbocharger rotor system are tested to obtain the speed and vibration displacement signal voltages. Then, the signal voltage is transformed according to the proportional relationship between the signal voltage and the speed and displacement to obtain the rotor speed and vibration displacement (time domain vibration displacement). The measured vibration displacement is the time domain vibration displacement, and the time domain vibration displacement is Fourier transformed to obtain the frequency domain amplitude. The measured time domain vibration displacement corresponds to the vibration displacement calculated in the finite element dynamic model of the rotor system. The measured value of the time domain vibration displacement is analyzed in real time, that is, Fourier transform is performed to obtain the frequency domain amplitude and frequency domain waterfall diagram. The optimal external oil film clearance can be quickly selected based on the rotor speed measured by the speed sensor.

[0092] Since the rotor systems produced in batches all have parameter errors, the fuzzy PID control intelligent decision is used to fine-tune the external oil film gap. The details are as follows: First, the optimal external oil film gap under each speed range is used as a knowledge base, and then the basic method of fuzzy control theory is used for fuzzy reasoning. The fuzzy reasoning mechanism is to increase the optimal external oil film gap corresponding to the speed range by one unit, test and record the vibration displacement amplitude, and then decrease it by one unit, also test and record the vibration displacement amplitude, and compare it with the vibration displacement amplitude under the original external oil film gap. Finally, the external oil film gap corresponding to the smaller vibration displacement amplitude is taken as the finely adjusted external oil film gap.

[0093] Step S6 specifically includes:

[0094] According to the turbocharger rotor vibration active control strategy based on the speed segment, the optimal outer oil film clearance value of the actual turbocharger rotor system at the current speed is obtained;

[0095] adjusting the outer oil film value of the turbocharger rotor system to the optimal outer oil film value to obtain the vibration displacement of the turbocharger rotor system under optimal conditions;

[0096] The outer oil film value of the turbocharger rotor system is adjusted to the optimal outer oil film value plus a second preset value, to obtain the vibration displacement of the turbocharger rotor system after the oil film value is increased;

[0097] The outer oil film value of the turbocharger rotor system is adjusted to the optimal outer oil film value minus a third preset value, to obtain a vibration displacement of the turbocharger rotor system after the oil film value is reduced;

[0098] Compare the vibration displacement under the optimal condition, the vibration displacement after the oil film value is increased, and the vibration displacement after the oil film value is decreased to obtain the outer oil film value corresponding to the minimum value of the vibration displacement value;

[0099] Active control of the turbocharger rotor vibration is performed based on the outer oil film value corresponding to the minimum vibration displacement value as the fine-tuned outer oil film clearance.

[0100] In this embodiment, the present invention aims at the problems of frequent start and stop of turbocharger rotor system, large working speed range, fast speed change, long hysteresis time of traditional control method and poor control accuracy. It constructs a dynamic finite element model of turbocharger floating ring bearing rotor system with variable oil film gap, analyzes the influence of external oil film gap on the vibration response of rotor system, obtains the mapping relationship between external oil film gap of floating ring bearing and rotor vibration response under each speed segment, proposes a control strategy for sub-speed segment, and controls the vibration of high-speed rotor system quickly and accurately. It effectively reduces the vibration failure during rotor operation, ensures the safety and stability of turbocharger during operation, and prolongs the service life of turbocharger.

[0101] Taking the setting of 4 external oil film clearance values ​​as an example, the method of this implementation is explained:

[0102] The turbocharger floating ring bearing external oil film clearance is divided into 4 types from small to large, and a floating ring bearing rotor system dynamics finite element model with variable external oil film clearance is established. Through analysis, the time domain response vibration displacement full-frequency amplitude diagram and frequency domain response vibration displacement waterfall diagram of the rotor system in the full speed range with 4 types of external oil film clearance are obtained. The details are as follows:

[0103] (I) The finite element method is used to divide the rotor into multiple units along the axis, and the following is constructed: Figure 2 The finite element model of the turbocharger rotor system dynamics is shown in Figure 1. Figure 2 The midpoints 4 and 15 are the center of gravity of the turbine and impeller, respectively. Nodes 19 and 20 represent two floating ring bearings. The unbalance is loaded on the locking nut represented by node 17. In order to verify the correctness of the dynamic finite element model of the turbocharger floating ring bearing rotor system, the Bode diagram of the rotor system speed-up process is obtained through simulation calculation, as shown in Figure 3 As shown. Figure 3 It can be seen that the journal speed corresponding to the critical speed of the rotor system in the simulation is near the speed point of 56.4krmp. A vibration test bench for the turbocharger rotor system was built, and the journal speed corresponding to the critical speed of the rotor system measured on the test bench was 56krpm. The simulation results were in good agreement with the experimental test results, with an error within 5%, thus verifying the correctness of the parameter selection of the floating ring bearing rotor system dynamics finite element model.

[0104] The speed of the turbocharger rotor system changes quickly. For example, a certain type of gasoline engine turbocharger sometimes needs to accelerate from 0 to 240krpm within 3 seconds. When adjusting the bearing outer oil film gap to control the vibration of the rotor system in sub-speed intervals, the running time of each speed interval is short. If there are too many types of speed interval subdivisions, the running time of each speed interval is very short, even close to the hysteresis time (10 milliseconds) of the piezoelectric ceramic mechanism, which seriously affects the control effect. Therefore, the full speed range is divided into three speed sections: low, medium, and high. According to the rotor system accelerating from 0 to 240krpm in 3 seconds, the running time of each speed section is about 1000 milliseconds, which is much longer than the hysteresis time (10 milliseconds) of the piezoelectric ceramic mechanism, and a better control effect can be obtained.

[0105] In order to study the influence of the outer oil film clearance of floating ring bearing on the vibration response of turbocharger rotor system, Figure 2 In the dynamic finite element model shown in the figure, the same phase unbalance (0.10 g·mm) is applied at node 17 as the initial excitation of the system. The speed range of the speed increase simulation is 10-240 krpm. The dynamic finite element model is analyzed by the Newmark direct integration method, and the following is obtained: Figure 4 The time domain response vibration displacement full frequency amplitude diagram shown in Figure 5 The vibration amplitude waterfall diagram of the locking nut at different external oil film clearances is shown. Figure 5 The frequency division vibration of the inner and outer oil films is 0.2 times, and the frequency division vibration of the inner oil film is 0.5 times. When the outer oil film gap value increases from 0.030mm to 0.036mm, the rotor vibration is first dominated by the inner oil film frequency division vibration. As the outer oil film gap value gradually increases, the rotor vibration gradually changes to the outer oil film frequency division vibration. The radial vibration displacement of the rotor system locking nut is measured using the turbocharger vibration test bench, and the simulation and experimental results are in good agreement.

[0106] (ii) Based on the full-speed range time-domain response vibration displacement full-band amplitude diagram and frequency-domain response vibration displacement waterfall diagram obtained in point (i), the full speed range is divided into three speed segments: low, medium and high. The optimal external oil film clearance values ​​corresponding to the three speed segments are determined according to the principle of minimum vibration displacement amplitude and good stability, and the mapping relationship between the vibration displacement amplitude and the oil film clearance in the three speed segments is obtained.

[0107] pass Figure 4 and Figure 5It can be seen from the time domain and frequency domain vibration response graphs that: for this type of turbocharger, when the rotor speed is in the range of 0-90krpm, the outer oil film gap is 0.036mm, and neither the inner oil film frequency division vibration nor the outer oil film frequency division vibration occurs. The value of the outer oil film gap in this speed range is beneficial to vibration suppression; when the rotor speed is in the range of 90-180krpm, the outer oil film gap is 0.032mm, and there is only a small amount of inner oil film frequency division vibration and single frequency vibration. The value of the outer oil film gap in this speed range is beneficial to vibration suppression; when the rotor speed is in the range of 180-240krpm, the outer oil film gap is 0.030mm, and neither the inner oil film frequency division vibration nor the outer oil film frequency division vibration occurs. The value of the outer oil film gap in this speed range is beneficial to vibration suppression. Through the above analysis, combined with the through-frequency amplitude of the rotor system and the root mean square of each divided-frequency amplitude, the optimal outer oil film clearance for each speed range is obtained: when the rotor speed is in the range of 0-90krpm, the outer oil film clearance is 0.036mm, when the rotor speed is in the range of 90-180krpm, the outer oil film clearance is 0.032mm, and when the rotor speed is in the range of 180-240krpm, the outer oil film clearance is 0.030mm.

[0108] (III) Based on the mapping relationship between the vibration displacement amplitude of the rotor system and the outer oil film clearance of the floating ring bearing under the above speed sections, a control strategy for regulating the outer oil film clearance of the floating ring bearing in different speed sections to suppress the vibration of the turbocharger rotor system is constructed, such as Figure 6 shown.

[0109] The turbocharger rotor accelerates quickly and operates at a high speed. Based on current technology, it is still difficult to actively control the speed of such small high-speed rotors during operation. From the mapping relationship between the outer oil film clearance of the floating ring bearing and the vibration displacement amplitude at each speed range, it can be seen that there is an optimal bearing clearance that can effectively suppress the rotor vibration corresponding to the allowable vibration amplitude at different speed ranges. Therefore, the present invention innovatively proposes the following Figure 6 The active control strategy of turbocharger rotor vibration based on speed segment is shown. First, the vibration of the rotor system is tested through vibration sensing, and then the amplitude of the vibration signal in the time and frequency domain is analyzed in real time; then, according to the mapping relationship between the outer oil film gap of the floating ring bearing and the vibration response in each speed segment in (II), the speed of the rotor system detected by the speed sensor is used. Since different speed segments correspond to different optimal outer oil film gaps, the outer oil film gap is quickly selected according to the speed; since there are parameter errors in the mass-produced turbocharger rotor systems, fuzzy PID control intelligent decision-making is used to fine-tune the outer oil film gap of the floating ring bearing; finally, the piezoelectric ceramic mechanism driving voltage corresponding to the fine-tuned outer oil film gap is output, and it is quickly and accurately executed to drive the movable bearing to move, adjust the outer oil film gap of the floating ring bearing, and control the vibration of the rotor system.

[0110] Example 2

[0111] like Figure 7 As shown, this embodiment provides a turbocharger rotor vibration active control device, the device comprising: a retractable piezoelectric ceramic mechanism 7-1, a controller (not shown in the figure) connected to the retractable piezoelectric ceramic mechanism 7-1 through a wire 7-7, a bearing seat 7-2, a fixed bearing 7-3 fixedly connected to the bearing seat 7-2, a movable bearing 7-4 slidably connected to the bearing seat 7-2, a floating ring 7-5 provided in an area surrounded by the fixed bearing 7-3 and the movable bearing 7-4, and a journal 7-6 provided in the floating ring 7-5;

[0112] A gap is provided between the fixed bearing bush 7-3 and the movable bearing bush 7-4;

[0113] The controller is used to execute the method described in claim embodiment 1;

[0114] The retractable piezoelectric ceramic mechanism 7-1 includes a retractable part and a fixed part; the fixed part is fixedly connected to the bearing seat 7-2;

[0115] The telescopic part is fixedly connected to the movable bearing bush 7-4;

[0116] The retractable piezoelectric ceramic mechanism 7-1 is used to drive the movable bearing 7-4 to move in a direction close to or away from the fixed bearing 7-3 under a driving voltage corresponding to the external oil film clearance value output by the controller.

[0117] The gap between the floating ring 7-5 and the upper and lower bearing shells is the outer oil film gap of the floating ring bearing. The journal 7-6 is located inside the floating ring 7-5. The gap between the journal 7-6 and the floating ring 7-5 is the inner oil film gap of the floating ring bearing.

[0118] Piezoelectric ceramics are packaged in a metal shell to form a piezoelectric ceramic mechanism. Within the working voltage range of the piezoelectric ceramic mechanism, the higher the voltage, the greater the elongation of the piezoelectric ceramic mechanism along the vertical direction, that is, the piezoelectric ceramic mechanism elongates as the working voltage increases, and shortens as the working voltage decreases.

[0119] The telescopic part of the piezoelectric ceramic mechanism is provided with a mounting interface, which is embedded in the bottom groove of the movable bearing 7-4 through interference fit. When the piezoelectric ceramic mechanism is energized, its length changes, driving the movable bearing 7-4 to move, causing the outer oil film gap of the floating ring bearing to change.

[0120] The outer oil film gap of the floating ring bearing can be reduced by driving the movable bearing 7-4 upward through the piezoelectric ceramic mechanism, and the outer oil film gap of the floating ring bearing can be increased by driving the movable bearing 7-4 downward through the piezoelectric ceramic mechanism, thereby obtaining different outer oil film gaps of the floating ring bearing.

[0121] Based on the millisecond response speed and high displacement accuracy of piezoelectric ceramics, the construction Figure 7 The floating ring bearing outer oil film clearance adjustment device shown in the figure can adjust the outer oil film clearance of the floating ring bearing. The floating ring bearing outer oil film clearance adjustment device adopts an upper and lower bearing shell structure, wherein the upper bearing shell is fixed and the lower movable bearing shell 7-4 can move slightly along the vertical guide groove. The piezoelectric ceramic mechanism is fixedly connected to the lower movable bearing shell 7-4 to minimize the control displacement error, and the piezoelectric ceramic mechanism drives the lower bearing shell to move up and down, thereby changing the outer oil film clearance of the floating ring bearing.

[0122] In this embodiment, the outer oil film gap is adjusted by a retractable piezoelectric ceramic mechanism, which has a simple structure and is easy to operate.

[0123] The principles and implementation methods of the present invention are described in this article using specific examples. The description of the above embodiments is only used to help understand the method and core idea of ​​the present invention. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A method for actively controlling vibration of a turbocharger rotor, characterized in that: The method comprises: Establish a finite element dynamics model of the turbocharger rotor system with the outer oil film clearance of the floating ring bearing; According to the finite element dynamics model of the turbocharger rotor system, a full speed range speed increase simulation is performed under different external oil film gap conditions to obtain a time domain response vibration displacement full-frequency amplitude diagram and a frequency domain response vibration displacement waterfall diagram under each external oil film gap; Dividing the time domain response vibration displacement full-frequency amplitude diagram and the frequency domain response vibration displacement waterfall diagram under each of the outer oil film gaps into speed segments; In the same speed section divided in all the time domain response vibration displacement full-frequency amplitude diagrams and the frequency domain response vibration displacement waterfall diagrams, the principle of minimum full-frequency vibration displacement amplitude and minimum root mean square amplitude of each divided frequency is applied to determine the optimal outer oil film clearance value corresponding to each speed section; According to the optimal outer oil film clearance value corresponding to each speed segment, constructing a turbocharger rotor vibration active control strategy based on the speed segment; Active control of the turbocharger rotor vibration is performed according to the turbocharger rotor vibration active control strategy based on the speed-specific segment.

2. The method according to claim 1, characterized in that: The dynamic expression of the finite element dynamic model of the turbocharger rotor system is: Among them, M1 is the mass matrix of the rotor system, C1 is the damping matrix, K1 is the stiffness matrix, ρ is the vibration displacement, is the vibration acceleration; is the vibration velocity; u is the external excitation force.

3. The method according to claim 1 or 2, characterized in that: According to the finite element dynamics model of the turbocharger rotor system, under the condition of different external oil film gaps, a full speed range speed increase simulation is performed to obtain a time domain response vibration displacement full-frequency amplitude diagram and a frequency domain response vibration displacement waterfall diagram under each external oil film gap, specifically including: Under each of the outer oil film gaps, the finite element dynamics model of the turbocharger rotor system is analyzed by using the Newmark direct integration method, and based on the assumption of the average long acceleration, the vibration displacement of the turbocharger rotor under different speeds is obtained; The time domain response vibration displacement full frequency amplitude diagram is constructed with time as the abscissa and the vibration displacement as the ordinate; Performing Fourier transform on the vibration displacement to obtain frequency domain amplitudes of the vibration displacement at different rotation speeds; The frequency domain response vibration displacement waterfall diagram is constructed with frequency as the horizontal coordinate, the frequency domain amplitude as the vertical coordinate, and the rotation speed as the vertical coordinate.

4. The method according to claim 1, characterized in that The dividing of the time domain response vibration displacement full-frequency amplitude diagram and the frequency domain response vibration displacement waterfall diagram under each of the outer oil film gaps into speed segments specifically includes: According to the speed range in which oil film vortex appears in the oil film frequency division vibration inside the floating ring bearing, the speed range in which oil film oscillation appears, and the speed range in which the oil film frequency division vibration outside the floating ring bearing appears, the time domain response vibration displacement full-frequency amplitude diagram and the frequency domain response vibration displacement waterfall diagram under each of the outer oil film gaps are divided into speed segments.

5. The method according to claim 1, characterized in that: The establishment of the finite element dynamics model of the turbocharger rotor system including the outer oil film clearance of the floating ring bearing also includes: Constructing a simulation model of the turbocharger rotor system finite element dynamics model; The simulation model is simulated to obtain a Bode diagram of the rotor system during the speed increase process; Determine a journal speed simulation value corresponding to the critical speed of the rotor system according to the Bode diagram; Performing actual vibration testing on the finite element dynamics model of the turbocharger rotor system to obtain a measured value of the journal speed corresponding to the critical speed of the rotor system; Determine whether the error between the simulated value of the journal speed and the measured value of the journal speed is less than a preset value; If so, the finite element dynamics model of the turbocharger rotor system is verified.

6. The method according to claim 1, characterized in that The active control of the turbocharger rotor vibration according to the turbocharger rotor vibration active control strategy based on the speed segment specifically includes: According to the turbocharger rotor vibration active control strategy based on the speed segment, the optimal outer oil film clearance value of the actual turbocharger rotor system at the current speed is obtained; adjusting the outer oil film value of the turbocharger rotor system to the optimal outer oil film value to obtain the vibration displacement of the turbocharger rotor system under optimal conditions; The outer oil film value of the turbocharger rotor system is adjusted to the optimal outer oil film value plus a second preset value, to obtain the vibration displacement of the turbocharger rotor system after the oil film value is increased; The outer oil film value of the turbocharger rotor system is adjusted to the optimal outer oil film value minus a third preset value, to obtain a vibration displacement of the turbocharger rotor system after the oil film value is reduced; Compare the vibration displacement under the optimal condition, the vibration displacement after the oil film value is increased, and the vibration displacement after the oil film value is decreased to obtain the outer oil film value corresponding to the minimum value of the vibration displacement value; Active vibration control of the turbocharger rotor is performed according to the outer oil film value corresponding to the minimum vibration displacement value.

7. A device for actively controlling the vibration of a turbocharger rotor, characterized in that: The device comprises: a retractable piezoelectric ceramic mechanism, a controller connected to the retractable piezoelectric ceramic mechanism by wire, a bearing seat, a fixed bearing bush fixedly connected to the bearing seat, a movable bearing bush slidably connected to the bearing seat, a floating ring arranged in an area surrounded by the fixed bearing bush and the movable bearing bush, and a journal arranged in the floating ring; A gap is provided between the fixed bearing bush and the movable bearing bush; The controller is used to execute the method according to any one of claims 1 to 6; The retractable piezoelectric ceramic mechanism comprises a retractable part and a fixed part; the fixed part is fixedly connected to the bearing seat; The telescopic portion is connected to the movable bearing bush; The retractable piezoelectric ceramic mechanism is used to drive the movable bearing to move in a direction close to or away from the fixed bearing under a driving voltage corresponding to the outer oil film clearance value output by the controller.

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