Autonomous monitoring and balancing screw air compressor and vibration suppression method

Abstract

The invention discloses an automatic monitoring and balancing screw air compressor and a vibration suppression method, the automatic monitoring and balancing screw air compressor comprises a compressor main body, a power driving unit and a vibration monitoring and suppression system, and the power driving unit comprises a coding type permanent magnet motor and a flexible coupler. The vibration monitoring and suppression system is characterized in that four groups of FBG sensors are arranged on the driving shaft and the driven shaft, three FBG sensors are arranged in each group along the circumferential direction of the shaft at intervals of 120 degrees, heat-conducting silicone grease is sprayed on the surfaces of the FBG sensors and matched with cooling fins to realize temperature protection, and vibration interference is reduced through a buffer pad; a signal is accessed to the demodulator through the optical fiber and the optical fiber slip ring; the demodulator realizes fault diagnosis through a fusion algorithm of a fiber bragg grating coupling response mechanism; the controller solves the problems that a traditional screw air compressor is low in vibration monitoring precision and poor in vibration suppression effect through the closed-loop design of FBG sensing, intelligent diagnosis and self-adaptive vibration suppression based on the diagnosis result, and is suitable for efficient and stable air source supply in the industrial field.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of air compressors, and particularly relates to a screw air compressor with autonomous monitoring and balancing and a vibration suppression method. BACKGROUND

[0002] As a core air supply equipment in modern industrial production, screw air compressors are widely used in the fields of mechanical manufacturing, chemical industry, food processing, energy exploitation, etc., and the stability and reliability of the operation of the screw air compressors are directly related to the industrial production efficiency and equipment safety. With the development demand of industrial intelligentization and high efficiency, higher requirements are put forward for the vibration control of the screw air compressors, and exploring the vibration roots of the air compressors and seeking precise diagnosis and effective suppression technology have become the key research direction for guaranteeing the long-period stable operation of the equipment.

[0003] The operation process of the screw air compressor involves the coupling of mechanical dynamics, fluid dynamics, thermodynamics and other multiple physical fields, and the vibration causes of the screw air compressor are complex and interrelated. With the development of the equipment towards high speed and high pressure, the problems such as pipeline vibration caused by airflow pulsation, mechanical vibration caused by rotor imbalance, abnormal vibration caused by structural resonance, and nonlinear vibration caused by friction instability are increasingly prominent. The traditional diagnosis method based on shell vibration monitoring has the limitations of low precision and slow response, and it is difficult to capture the subtle strain changes and temperature fluctuations of the key parts of the rotor. At the same time, the existing vibration suppression technologies mostly adopt passive structure optimization or single control strategy, and cannot realize the coordinated suppression of multiple source vibrations, resulting in equipment vibration overrun, energy consumption increase, and even fault shutdown caused by vibration. Therefore, it is urgent to develop a screw air compressor system integrating high-precision in-situ monitoring and intelligent closed-loop vibration suppression, so as to break through the technical bottleneck of the traditional technology and realize precise diagnosis and efficient treatment of complex vibration problems. SUMMARY

[0004] In order to solve the problems in the prior art, the application provides a screw air compressor with autonomous monitoring and balancing, so as to solve the problems such as low vibration monitoring precision, single vibration suppression means, and difficulty in solving structural resonance and fluid instability of the screw air compressor in the prior art. The air compressor can realize direct diagnosis of the strain and temperature characteristics of the shaft section in the neighborhood of the rotor bearing; realize full-automatic closed-loop vibration suppression from vibration monitoring, intelligent diagnosis to active control; realize coordinated suppression of multiple source vibrations such as airflow pulsation, structural resonance, rotor imbalance and thermal deformation, effectively solve the stubborn vibration problems that cannot be handled by the traditional maintenance means, and significantly improve the equipment operation stability and energy efficiency.

[0005] In order to achieve the above-mentioned objectives, in a first aspect, the present invention provides a self-monitoring and balancing screw air compressor, including a compressor body and a vibration monitoring and suppression system, a driving shaft and a driven shaft are arranged in the compressor body, angular contact ball bearings are arranged at both ends of the driving shaft and the driven shaft, FBG sensors are arranged at the places where the angular contact ball bearings are installed on the driving shaft and the driven shaft, and multiple FBG sensors are evenly arranged around a cross section, the FBG sensors are connected to armored optical fibers, the armored optical fibers pass through the driving shaft and the driven shaft, and the armored optical fibers are connected to a fiber grating demodulator through a fiber slip ring.

[0006] Furthermore, grooves are provided on the driving shaft and the driven shaft for installing FBG sensors, a buffer pad is provided at the bottom of the groove, thermal grease is coated on the outside of the FBG sensor, and a heat sink is provided between the FBG sensor and the inner wall of the groove.

[0007] Furthermore, flange end covers are provided at the driven end of the driving shaft and both ends of the driven shaft, and the driving end of the driving shaft is connected to the output end of the encodable permanent magnet motor through a flexible coupling; a cathode screw rotor is provided on the driven shaft, and an anode screw rotor is provided on the driving shaft.

[0008] Furthermore, three FBG sensors are evenly distributed in each cross section along the circumference of the shaft at an angle of 120°; and dynamic balancing rings are installed on the active shaft and the driven shaft.

[0009] Furthermore, the optical fiber slip ring is a miniature hollow shaft slip ring with a rotation speed support of ≥10,000 rpm and an optical coupling loss of ≤0.3 dB; the outer layer of the armored optical fiber is wrapped with a polyimide wear-resistant coating with a coating thickness of 50 μm and a temperature resistance of ≥250°C.

[0010] Furthermore, the efficiency level of the encodable permanent magnet motor is not lower than IE4, and the rotor shaft extension end is rigidly connected to the driving shaft through a flexible coupling.

[0011] In a second aspect, the present invention provides a method for suppressing vibration of a screw air compressor, based on the above-mentioned screw air compressor, comprising the following steps: Obtain the wavelength offset Δλ of the reflected light from the FBG sensor, and calculate the strain and temperature of the active and driven shafts based on the wavelength offset Δλ. The fiber Bragg grating (FBG) demodulator analyzes the wavelength drift and identifies the vibration source through a fusion algorithm that combines multi-level discrete wavelet transform with the fiber Bragg grating coupling response mechanism. Based on the vibration source analysis results, the controller controls the speed and frequency of the encodable permanent magnet motor through PID, and drives the dynamic balancing ring to adjust the counterweight position to change the eccentricity to achieve active vibration suppression.

[0012] Furthermore, the fiber Bragg grating demodulator analyzes the wavelength drift and identifies the vibration source through a fusion algorithm of multi-level discrete wavelet transform and fiber Bragg grating coupling response mechanism, including the following steps: Sd1, FBG demodulator receives FBG reflected light signal, and wavelength shift Δλ is obtained after photoelectric conversion, Sd2, using multi-stage discrete wavelet transform method, in the i+1 stage decomposition, low frequency component and high frequency component are calculated by the following formula:

[0013] In the formula, is the i+1 stage low frequency approximation coefficient, reflecting the basic trend of the signal, i.e. temperature change; is the i+1 stage high frequency detail coefficient, reflecting the rapid fluctuation of the signal, i.e. strain vibration; i is the i+1 stage high frequency detail coefficient, reflecting the rapid fluctuation of the signal, i.e. strain vibration; is the i+1 stage high frequency detail coefficient, reflecting the rapid fluctuation of the signal, i.e. strain vibration; i is the low frequency component after i+1 stage decomposition; is the low-pass filter coefficient, is the high-pass filter coefficient; N is the filter length, k is the discrete time series index.

[0014] Sd3, the low frequency approximation coefficient and the high frequency detail coefficient are combined with their frequency characteristics, amplitude changes and coupling relationship with temperature strain to distinguish different vibration sources.

[0015] Further, according to the fiber grating coupling response mechanism, the strain and temperature difference are obtained based on the following formula:

[0016] In the formula, is the initial Bragg wavelength, is the strain sensitivity coefficient, is the micro-strain of the sensor sensing axis body, is the temperature sensitivity coefficient, is the relative temperature change of the axis body.

[0017] Further, the low frequency approximation coefficient and the high frequency detail coefficient are combined with their frequency characteristics, amplitude changes and coupling relationship with temperature strain to distinguish different vibration sources, and the specific judgment is as follows: Rotor dynamic balance failure: - Corresponding to the periodic amplitude fluctuation in the 10-100 Hz frequency band with the same frequency as the rotor speed, and the amplitude increases linearly with the increase of the speed; Pneumatic pulsation impact: - Pulse high-frequency components appear in the 10-100Hz frequency band, a characteristic peak consistent with the airflow pulsation frequency exists in the spectrum, and the pulse interval has a nonlinear relationship with the rotor speed; Structural resonance: - In the 200-500Hz frequency band, the amplitude of a specific frequency component suddenly increases, and the frequency coincides with the natural frequency of the rotor or blade; Thermal deformation: - Corresponding to the <0.1Hz frequency band, a significant slow drift is presented, reflecting the temperature trend term, and a strain component that monotonically increases with temperature appears in the low-frequency detail coefficient.

[0018] Compared with the prior art, the present application has at least the following beneficial effects: Compared with the traditional single-axis monitoring scheme, the present application can realize synchronous acquisition of double-axis strain and temperature data, complete capture of the three-dimensional bending deformation characteristics of the rotor during rotation, and improve the monitoring coverage by using FBG sensors distributed at an interval of 120° on the driving shaft and the driven shaft.

[0019] The FBG sensor of the present application adopts a heat-conducting silicone grease setting heat sink combined with a buffer pad composite protection structure, the heat-conducting silicone grease cooperates with the heat sink to provide an effective working environment for the FBG sensor, effectively avoiding wavelength drift caused by high temperature; the buffer pad can still work stably under impact by absorbing high-frequency vibration energy, solving the problem of data distortion of traditional sensors in high-temperature and strong-vibration environments.

[0020] The present application is based on the in-shaft wiring scheme of the optical fiber slip ring, which breaks through the limitation of traditional wireless transmission by metal shielding and electromagnetic interference, realizes lossless transmission of optical signals in a rotating state; combined with a 1kHz high sampling rate demodulator, it can capture 0.1μm level strain changes of the rotor in real time, providing millisecond-level response data support for vibration suppression; the present application realizes the closed-loop design of FBG sensor, intelligent diagnosis and multi-method vibration suppression, integrates dynamic balance ring adjustment and motor parameter adaptive control, and the suppression rate of multi-source vibration is more than 70%, the vibration amplitude of the compressor is reduced to less than 50μm, the equipment maintenance cycle is extended by 30%, and the overall efficiency is improved by 15%-20%. BRIEF DESCRIPTION OF DRAWINGS

[0021] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiment description, wherein: Figure 1 It is a general assembly drawing of the screw air compressor; Figure 2 is a screw air compressor main body diagram; Figure 3 is a FBG sensor installation diagram; Reference signs: 10-compressor body; 11-driving shaft; 12-driven shaft; 13-flange end cover; 14-elastic sealing ring; 15-angular contact ball bearing; 16-anode screw rotor; 17-cathode screw rotor; 18-compressor shell; 20-codable permanent magnet motor; 21-flexible coupling; 30-FBG sensor; 31-radiator; 32-cushion pad; 33-armored optical fiber; 34-optical fiber slip ring; 35-optical fiber grating demodulator; 37-dynamic balance ring. DETAILED DESCRIPTION

[0022] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the specific embodiments of the present application will be described in detail below in combination with the drawings of the specification. Some simplifications or omissions may be made in this part and the abstract and title of the specification to avoid obscuring the purpose of this part, the abstract and the title, and such simplifications or omissions cannot be used to limit the scope of the present application.

[0023] The present application discloses a self-monitoring and balancing screw air compressor, comprising a compressor body 10, a power driving unit, a vibration monitoring and suppression system; Reference Figure 1 The compressor body 10 comprises a driving shaft 11, a driven shaft 12, a pair of flange end covers 13, a pair of elastic sealing rings 14, and a compressor shell 18 for sealing the screw air compressor shell. Angular contact ball bearings 15 are installed in pairs at both ends of the driving shaft 11 and the driven shaft 12. An anode screw rotor 16 is arranged on the driving shaft 11, and a cathode screw rotor 17 is arranged on the driven shaft 12 for compressing air.

[0024] A pair of flange end covers 13 are installed on the driving shaft 11 and tightly connected at both ends of the shaft through interference fit, which can effectively prevent external impurities from entering and provide sealing protection for internal components. A pair of elastic sealing rings 14 are arranged at the contact part of the flange end cover 13 and the shaft, further enhancing the sealing performance and avoiding gas leakage. Two pairs of angular contact ball bearings 15 are installed in pairs at both ends of the driving shaft 11 and the driven shaft 12, which can withstand large radial and axial loads and ensure the stability of the driving shaft 11 during high-speed rotation.

[0025] Reference Figure 2The anode screw rotor 16 is fixed to the driving shaft 11 by a key connection and rotates synchronously with the driving shaft 11. The profile of the anode screw rotor 16 is an asymmetric trochoid-epitrochoid meshing tooth profile. The volume ratio between the teeth is reduced by optimizing the profile design, and the gap precision is controlled within 0.01-0.03mm through precise machining gap control technology, effectively improving the adiabatic efficiency and reducing the internal leakage. The cathode screw rotor 17 on the driven shaft 12 meshes with the anode screw rotor 16 and rotates reversely synchronously under the driving of the driving shaft 11. The matching precision of the tooth profiles of the two rotors is 0.02mm, which ensures the air tightness of the compression chamber.

[0026] The driven shaft 12 is also equipped with a bearing support structure adapted to the structure of the driving shaft 11, including an angular contact ball bearing, a positioning spacer sleeve, and a sealing element. The elastic sealing ring 14 cooperates with the flange end cover 13 to ensure the coaxiality (radial runout ≤0.05mm) and operation stability of the compressor at high speed. The compressor housing 18 is made of high-strength cast iron (HT300) and has good pressure resistance and deformation resistance. The radial gap between the inner wall of the compressor housing 18 and the outer circle of the rotor is controlled within 0.1-0.15mm to reduce gas leakage. The compressor housing 18 is provided with an air inlet and an air outlet. A high-efficiency air filter device (filtering accuracy ≥99.9%) can be installed at the air inlet to further ensure the quality of the compressed gas.

[0027] The power driving unit includes an encoder permanent magnet motor 20. The encoder permanent magnet motor 20 is connected to the driving shaft 11 through a flexible coupling 21 to transmit power to the screw air compressor. The control end of the encoder permanent magnet motor 20 is connected with a controller and a frequency converter, which can realize precise control of the encoder permanent magnet motor 20. The encoder permanent magnet motor 20 is selected to be a high-efficiency and energy-saving encoder permanent magnet motor with an efficiency level ≥IE4. It has high power density and efficiency, and can provide strong power output for the compressor. The speed of the motor can be accurately adjusted by the frequency controller with an adjustment accuracy of ±1r / min to adapt to different working loads and working conditions. The shaft of the encoder permanent magnet motor 20 is connected to the driving shaft 11 through the flexible coupling 21, which can effectively compensate for the installation errors and radial and axial displacements between the two shafts, reducing the vibration and noise caused by misalignment of the shaft system.

[0028] Reference Figure 3Wherein figure a is the FBG sensor 30 in the active shaft 11 installation position schematic diagram, figure b is a FBG sensor 30 on the interface schematic diagram, figure c is a FBG sensor 30 in the slot installation schematic diagram; dynamic monitoring and suppression system includes FBG sensor, signal transmission component, data processing unit and vibration suppression actuator. FBG sensor 30 is arranged in the angular contact ball bearing 15 installation position at both ends of the active shaft 11 and the driven shaft 12, a section a group, a group three, FBG sensor 30 is installed in the 3 slots that are arranged at 120 ° interval in the circumferential direction of the active shaft 11 and the driven shaft 12, and one FBG sensor 30 is arranged in each slot. A layer of heat-conducting silicone grease is sprayed on the surface of the FBG sensor 30, the heat-conducting silicone grease has good heat-conducting performance, can rapidly conduct the heat generated by the FBG sensor 30 away, and avoids that the performance of the FBG sensor 30 is influenced due to excessively high temperature. The 0.5mm-thick heat sink 31 is attached in the groove around the FBG sensor 30, and the heat dissipation effect is further enhanced. Meanwhile, the 0.2mm-thick buffer pad 32 is additionally arranged between the contact surface of the FBG sensor 30 and the rotor, the buffer pad 32 has good elasticity and damping characteristics, can effectively reduce the interference of vibration on the sensor, and improves the measurement accuracy of the sensor. The buffer pad 32 is made of silicone rubber material.

[0029] The active shaft 11 and the driven shaft 12 are provided with fiber holes in the centers, the armored optical fiber 33 is transmitted out from the fiber hole in the center of the shaft and connected to the fiber-optic slip ring 34, and the fiber-optic slip ring 34 is connected to the fiber grating demodulator 35; the active shaft 11 and the driven shaft 12 are both provided with dynamic balance rings 37.

[0030] The FBG sensor 30 is integrally connected by arc discharge to fuse the tail fiber of the FBG sensor and the fiber core of the armored optical fiber. When the rotor operates, the FBG sensor 30 is subjected to the coupling action of airflow impact force, centrifugal stress and thermal stress, so that the central wavelength is offset, and signal acquisition is realized. After being processed by the fiber grating demodulator 35, the FBG sensor 30 can accurately monitor the bending deformation, axial stress state and temperature distribution characteristics of the rotor.

[0031] The signal transmission component includes the armored optical fiber, the through hole in the shaft and the fiber-optic slip ring. In order to realize reliable transmission of the FBG sensor 30 signal, the fiber hole is formed in the shaft in the axial direction, and the armored optical fiber 33 is transmitted out from the center of the shaft. The armored optical fiber 33 has good mechanical strength and anti-interference performance, can stably transmit optical signals during the rotation of the shaft, avoids friction and collision between the armored optical fiber 33 and other parts in the shaft, and ensures the safety of the optical fiber.

[0032] The optical fiber slip ring 34 is used as a core transmission component to realize optical signal connection between the driving shaft 11 and the driven shaft 12 and the static system. The armored optical fiber 33 led in the driving shaft 11 and the driven shaft 12 is connected to the rotating end of the optical fiber slip ring 34, and the fixed end of the optical fiber slip ring 34 is connected to the fiber grating demodulator through a single-mode optical fiber. By using the precise optical contact and rotary transmission technology, the coupling loss is less than or equal to 0.3 dB, and the dynamic signal collected by the FBG sensor 30 is transmitted to the fiber grating demodulator 35 without loss and delay.

[0033] The data processing unit includes a fiber grating demodulator and a controller. The sampling frequency of the fiber grating demodulator is 1 kHz, and the wavelength resolution is less than or equal to 1 pm. The optical signal can be converted into a digital wavelength offset in real time. In order to realize effective separation of the rotor composite signal, the strain and temperature data given by the fiber grating demodulator 35 are used. By using the coupling response mechanism of the fiber grating and the multi-stage discrete wavelet transform algorithm, the low-frequency temperature trend item and the high-frequency vibration disturbance signal are separated from the data, and the vibration source type is identified.

[0034] The vibration suppression execution mechanism includes a dynamic balance ring 37 and an adjustment module of a power drive unit. The dynamic balance ring 37 adopts a double eccentric ring structure, and the position of the counterweight block is adjusted by a stepping motor drive. The adjustment accuracy is ±0.1 mm. A balance force equal in size and opposite in direction to the unbalanced force is generated. When the vibration amplitude of the driving shaft 11 and the driven shaft 12 is monitored to exceed the set threshold value, for example, the threshold value is 50 μm, the dynamic balance adjustment action is automatically started, and the response time is less than or equal to 200 ms.

[0035] Based on the monitored bending strain, axial force and temperature gradient data, the controller uses a PID control algorithm to adjust the motor speed and torque parameters of the power drive unit in real time to optimize the operating conditions of the compressor and reduce vibration and noise. When serious vibration exceeding the adjustment range is detected, the controller automatically triggers the protection mechanism to stop the operation of the compressor and reports alarm information through an industrial bus. The alarm information includes a fault code and vibration characteristic data.

[0036] The principle and working process of the application are as follows: a: The programmable permanent magnet motor 20 receives the vector frequency conversion instruction of the controller, and adjusts the speed in the range of 1000-6000 rpm without step. The torque is transmitted to the driving shaft 11 through the flexible coupling 21. The driving shaft 11 drives the anode screw rotor 16 and the cathode screw rotor 17 on the driven shaft 12 to high-speed meshing, compresses the air along the spiral groove to 0.8-1.5 MPa, and generates periodic gas force excitation at the same time.

[0037] b: Under the high-speed rotation of the screw air compressor rotor, the FBG sensor 30 under the inner ring of the angular contact ball bearing 15 directly contacts the bearing load area, such as Figure 3 As shown, the micro-strain of the shaft is sensed, the FBG sensor reflects the wavelength offset Δλ of the light, and the demodulator demodulates the digital signal according to the wavelength offset Δλ, and the strain and temperature changes are obtained according to the wavelength offset Δλ. c) Armored optical fiber 33, installed in a fine channel within the shaft, resists centrifugal forces and oil corrosion. It transmits optical signals to the outside of the screw air compressor. Fiber slip ring 34 utilizes a multi-channel rotating optical coupler with an insertion loss of less than 0.5 dB, allowing the rotor to continuously transmit optical signals to fiber Bragg grating interrogator 35 even at a high speed of 6000 rpm.

[0038] d: The fiber Bragg grating demodulator 35 converts the received optical signal into a digital wavelength offset. The fault diagnosis is performed using a fusion algorithm combining multi-level discrete wavelet transform and fiber Bragg grating coupling response mechanism. The analysis shows that the vibration is caused by rotor dynamic balance failure, airflow pulsation impact, structural resonance, and thermal deformation. The fusion algorithm combining multi-level discrete wavelet transform and fiber Bragg grating coupling response mechanism includes: Sd1, the fiber Bragg grating demodulator 35 receives the FBG reflected light signal and obtains the wavelength shift Δλ after photoelectric conversion. According to the fiber Bragg grating coupling response mechanism, it is shown as follows:

[0039] Where, is the initial Bragg wavelength, is the strain sensitivity coefficient, The sensor senses the micro-strain of the shaft. is the temperature sensitivity coefficient, is the relative temperature change of the shaft.

[0040] Sd2 uses a multi-level discrete wavelet transform method. In the i+1th level decomposition, the low-frequency component and the high-frequency component are calculated by the following formula:

[0041] Where: is the i+1th level low-frequency approximation coefficient, reflecting the basic trend of the signal, i.e., temperature change; For the i The high-frequency detail coefficient of level +1 reflects the rapid fluctuation of the signal, that is, strain vibration; For the i The low-frequency component after level decomposition; is the low-pass filter coefficient, is the high-pass filter coefficient; N is the filter length, kIndexing for discrete time series.

[0042] Sd3, low-frequency approximation coefficient obtained by multi-stage discrete wavelet transform and high-frequency detail coefficient Combined with its frequency characteristics, amplitude variation and coupling relationship with temperature strain, different vibration sources can be distinguished, and specific judgments are as shown below. Rotor dynamic balance failure: periodic amplitude fluctuation with the same frequency as the rotor speed appears in the high-frequency detail coefficient, and the amplitude increases linearly with the increase of the speed.

[0043] Pneumatic pulsating impact: high-frequency detail coefficient appears pulse high-frequency component, and there is a characteristic peak in the spectrum consistent with the airflow pulsation frequency, and the pulse interval is nonlinearly related to the rotor speed; Structural resonance: the amplitude of a specific frequency component in the high-frequency detail coefficient suddenly increases, and the frequency is consistent with the natural frequency of the rotor or blade.

[0044] Thermal deformation: the low-frequency approximation coefficient presents a significant slow drift, reflecting the temperature trend term. At the same time, a strain component that monotonically increases with temperature rise appears in the low-frequency detail coefficient.

[0045] e: According to the analyzed vibration reason, the controller can control the speed and frequency of the encodable permanent magnet motor 20 and the counterweight position of the dynamic balance ring 37, and suppress the vibration within the adjustable range through PID control. If the controller detects a serious vibration reason and cannot suppress the vibration through control, the controller will stop the work of the screw air compressor and report the alarm content, and manual maintenance is performed.

[0046] The screw air compressor based on FBG sensing and vibration suppression of the application realizes accurate positioning of the vibration source and online dynamic suppression through the collaborative innovation of the rotor body embedded FBG array and the double-axis active balance ring.

[0047] In summary, the above embodiments are intended to illustrate the technical solutions of the application, not to limit them. Even if the application is described in detail according to the preferred embodiments, those skilled in the art can modify or replace the technical solutions of the application. As long as these changes do not deviate from the core spirit and protection scope of the application, they should be included in the protection scope defined by the claims of the application.

Claims

1. An autonomous monitored and balanced screw air compressor, characterized by, The application relates to a vibration monitoring and suppressing system of a compressor main body (10), wherein a driving shaft (11) and a driven shaft (12) are arranged in the compressor main body (10), and an angular contact ball bearing (15) is arranged at both ends of the driving shaft (11) and the driven shaft (12); an FBG sensor (30) is arranged at the position where the angular contact ball bearing (15) is arranged on the driving shaft (11) and the driven shaft (12); a plurality of FBG sensors (30) are uniformly arranged at one section; the FBG sensor (30) is connected with an armored optical fiber (33); the armored optical fiber (33) penetrates through the driving shaft (11) and the driven shaft (12); and the armored optical fiber (33) is connected with a fiber grating demodulator (35) through an optical fiber slip ring (34).

2. The self-monitoring and balanced screw-type air compressor of claim 1, wherein, A groove is arranged on the driving shaft (11) and the driven shaft (12) for mounting the FBG sensor (30), a buffer pad (32) is arranged at the bottom of the groove, the FBG sensor (30) is coated with heat-conducting silicone grease outside, and a cooling fin (31) is arranged between the FBG sensor (30) and the inner wall of the groove.

3. The self-monitoring and balanced screw-type air compressor of claim 1, wherein, Flange end covers (13) are arranged at the driving end of the driving shaft (11) and the two ends of the driven shaft (12); the driving end of the driving shaft (11) is connected with the output end of a codeable permanent magnet motor (20) through a flexible coupling (21); a cathode screw rotor (17) is arranged on the driven shaft (12); and an anode screw rotor (16) is arranged on the driving shaft (11).

4. The self-monitoring and balanced screw-type air compressor of claim 1, wherein, Three FBG sensors (30) are uniformly distributed at each section along the shaft circumferential direction at an angle of 120 degrees; and a dynamic balance ring (37) is arranged on the driving shaft and the driven shaft.

5. The self-monitoring and balanced screw-type air compressor of claim 1, wherein, The optical fiber slip ring (34) is a micro hollow shaft slip ring, the rotating speed support is greater than or equal to 10000 rpm, and the optical coupling loss is less than or equal to 0.3 dB; and the outer layer of the armored optical fiber (33) is wrapped with a polyimide wear-resistant coating, and the temperature resistance is greater than or equal to 250 DEG C.

6. The self-monitoring and balanced screw-type air compressor of claim 1, wherein, The efficiency grade of the codeable permanent magnet motor (20) is not lower than IE4, and the rotor shaft extension end is rigidly connected with the driving shaft through the flexible coupling (21).

7. A method of vibration suppression based on the screw air compressor according to any one of claims 1 to 6, characterized by, The application further relates to a vibration monitoring and suppressing method of a compressor main body (10), and the method comprises the following steps: The wavelength shift amount Delta Lambda of the reflected light of the FBG sensor (30) is acquired, and the strain and temperature of the driving shaft (11) and the driven shaft (12) are obtained according to the wavelength shift amount Delta Lambda; The fiber grating demodulator (35) analyzes the wavelength shift amount, and identifies the vibration source through a fusion algorithm of multi-level discrete wavelet transform and fiber grating coupling response mechanism; Based on the analysis result of the vibration source, the controller controls the rotating speed and frequency of the codeable permanent magnet motor (20) through PID control, and drives the dynamic balance ring (37) to adjust the counterweight position to change the eccentricity, so that the vibration is actively suppressed.

8. The vibration suppression method of a screw air compressor according to claim 7, characterized by, The wavelength shift amount is analyzed by the fiber grating demodulator (35), and the vibration source is identified through a fusion algorithm of multi-level discrete wavelet transform and fiber grating coupling response mechanism, which comprises the following steps: Sd1, the fiber grating demodulator (35) receives the FBG reflected light signal, and obtains the wavelength shift Delta Lambda after photoelectric conversion, Sd2, a multi-level discrete wavelet transform method is adopted, and in the i+1 level decomposition, the low-frequency component and the high-frequency component are calculated through the following formula: wherein are the i+1st order low frequency approximation coefficients, reflecting the basic trend of the signal, i.e. the temperature change; are the i+1st order high frequency detail coefficients, reflecting the fast fluctuations of the signal, i.e. the strain oscillations; i are the i+1st order high frequency detail coefficients, reflecting the fast fluctuations of the signal, i.e. the strain oscillations; are the i+1st order low frequency approximation coefficients after decomposition; i are the i+1st order low frequency approximation coefficients after decomposition; are the low pass filter coefficients, are the high pass filter coefficients; N is the filter length, k is the discrete time series index; Sd3, low frequency approximation coefficients obtained by multi-level discrete wavelet transform and high frequency detail coefficients Combining the frequency characteristics, amplitude changes and coupling relationship with temperature strain, different vibration sources are distinguished.

9. The vibration suppression method of a screw air compressor according to claim 7, characterized by, According to the fiber grating coupling response mechanism, the strain and temperature difference are obtained based on the following formula: wherein is the initial Bragg wavelength, is the strain sensitivity coefficient, is the micro-strain of the sensor sensing axis, is the temperature sensitivity coefficient, is the temperature change of the axis.

10. The vibration suppression method of a screw air compressor according to claim 7, characterized by, Low frequency approximation coefficients obtained by a multi-stage discrete wavelet transform and high frequency detail coefficients Combining the frequency characteristics, amplitude changes and coupling relationship with temperature strain, the specific judgment is as follows when distinguishing different vibration sources: Rotor dynamic balance failure: - Corresponding to the 10-100Hz frequency band, the periodic amplitude fluctuation with the same frequency as the rotor speed appears, and the amplitude increases linearly with the increase of the speed. Pneumatic pulsating impact: - Pulsating high-frequency components appear in the 10-100 Hz frequency band, there is a characteristic peak in the spectrum consistent with the airflow pulsation frequency, and the pulse interval has a nonlinear relationship with the rotor speed. Structural resonance: - In the 200-500 Hz band, the amplitude of a certain frequency component suddenly increases, and the frequency coincides with the natural frequency of the rotor or blade. Thermal deformation: - A significant slow drift is present for the <0.1 Hz band, reflecting the temperature trend term, and a strain component that monotonically increases with temperature is present in the low-frequency detail coefficients.

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