Oil-free and water-free vacuum pump device with automatic exhaust function based on acoustic emission

Abstract

The invention provides an oil-free and water-free vacuum pump device with an automatic exhaust function based on acoustic emission, and belongs to the technical field of vacuum pumps. In order to solve the problems that an existing oil-free and water-free vacuum pump is prone to overcompression, compression power consumption is increased, gas temperature rises, a screw rotor is scratched, a surface coating falls off and the like, an air inlet, an air outlet and a pump body of the vacuum pump are magnetically attracted by acoustic sensors, pressure relief openings are additionally arranged, and air pressure sound signals of the air inlet, the air outlet and a pump cavity are monitored in real time; the air pressure acoustic signal processing and analyzing module is used for processing and analyzing the air pressure acoustic signal in real time, the current air pressure state is judged and evaluated through the decision module, a pressure relief instruction is sent, and the over-compression phenomenon is avoided. In addition, motor matching power optimization and screw rotor abrasion state monitoring and analysis in the vacuum pump main machine are achieved, and efficient, stable and safe operation is ensured. The vacuum pump can meet the requirements for high-grade vacuum pumps in the technical fields of medical pharmacy, national defense military industry, semiconductors, chemical industry and the like.

Description

Technical Field

[0001] The invention relates to the technical field of vacuum pumps, and in particular to an oil-free and water-free vacuum pump device with an automatic exhaust function based on acoustic emission. Background Art

[0002] Oil-free and water-free screw vacuum pump is a power device that uses a high-speed synchronous counter-rotating screw to convert low-pressure gas into high-pressure gas. It is widely used in medical and pharmaceutical, national defense, chemical, semiconductor and refrigeration fields. Oil-free and water-free screw vacuum pumps often improve energy saving by increasing the compression ratio and reducing exhaust power consumption. However, high compression ratios can easily cause over-compression of gas in the pump body, and the air pressure in the cavity is higher than the exhaust pressure, which not only leads to increased compression power consumption and increased gas temperature, but also easily causes the screw rotor volume expansion to cause scratches and the screw rotor surface coating to fall off. Therefore, how to avoid the phenomenon of gas over-compression is a technical problem that needs to be solved during the design, production and use of screw vacuum pumps. In order to avoid the harm of gas over-compression, the compression ratio (usually less than 2:1) is controlled during the design stage of the screw vacuum pump to achieve the purpose of balancing compression power consumption and exhaust power consumption. However, low compression ratios cannot give full play to the potential of vacuum pumps in energy saving, cooling and noise reduction. High intake pressure requires the configuration of high-power motors, which can easily lead to high power consumption and high temperature heating and cause failures. By using variable frequency power supply and variable frequency motor, the frequency is reduced and the speed is slowed down at high intake pressure to control the pumping power, ensuring that the motor does not overload and heat up. However, low frequency and speed reduction operation will cause the effective pumping speed of the oil-free and water-free vacuum pump to decrease, prolong the pumping time in the high pressure stage, reduce the pumping efficiency and increase energy consumption. The patent (authorization number: ZL201080016680.6) discloses a screw vacuum pump, which has multiple overpressure outlets designed on the side wall of the pump body and a spherical overpressure valve. When the air pressure in the pump chamber is too high, the spherical overpressure valve is pushed open to release the pressure, thereby avoiding the occurrence of over-compression. However, the spherical overpressure valve relies on its own weight to repeatedly reset, and it is very easy to fail to close tightly under oil-free conditions, resulting in backflow leakage into the pump through the overpressure outlet during the subsequent pumping process, causing the pumping speed and ultimate vacuum degree of the vacuum pump to decrease. In addition, the multi-stage overpressure outlets are connected to the inner cavity of the pump body through the same connecting channel, and the holes of the front and rear stages are prone to "gas cross-talk", causing the pumped gas in the pump to circulate through the connecting channel. A horizontal oil-free and water-free air compressor with overpressure exhaust function (authorization number ZL201811021234.9) and a vertical oil-free and water-free air compressor with overpressure exhaust function (authorization number ZL201811019843.0) have announced improvement plans: by adding a pressure sensor to the air inlet or exhaust port and opening a pressure relief hole on the side wall of the pump body, the exhaust path of the over-compressed gas is pressure relief hole → pressure relief chamber → pressure relief valve → pressure relief pipe. However, the above patent scheme has three problems: first, the pressure sensor often works under overpressure, which seriously affects its accuracy and service life; second, the pressure sensor can only measure the inlet / outlet air pressure of the pump body, while in the actual operation of the vacuum pump, the screw rotates at high speed and gradually compresses the gas. The air pressure in each pitch area of ​​the screw may exceed the critical pressure, and the pressure sensor interface set in the middle of the vacuum pump body affects the operation of the screw; third, the wear status of the screw cannot be monitored in real time.Therefore, the present invention proposes an oil-free and water-free vacuum pump device with automatic exhaust function based on acoustic emission, magnetic acoustic sensors are installed at the air inlet, exhaust port and vacuum pump body, and a pressure relief port is added to monitor the air pressure sound signals of the air inlet, exhaust port and pump chamber in real time, and the air pressure sound signal processing and analysis module is used to perform real-time processing and analysis on the air pressure sound signal, and the decision-making module is used to judge and evaluate the current air pressure state, and send a pressure relief command to avoid over-compression; in addition, the motor matching power optimization and screw rotor wear state monitoring and analysis in the vacuum pump main engine are realized to ensure efficient, stable and safe operation of the oil-free and water-free air compressor, which has important practical application value. Summary of the invention

[0003] The present invention aims at the existing oil-free and water-free vacuum pumps, which are prone to over-compression, causing increased compression power consumption, increased gas temperature, scratches on the screw rotor, and shedding of the surface coating. An oil-free and water-free vacuum pump device with automatic exhaust function based on acoustic emission is proposed. Magnetic acoustic sensors are installed at the air inlet, exhaust port and vacuum pump body, and a pressure relief port is added. The air pressure sound signals at the air inlet, exhaust port and pump chamber are monitored in real time. The air pressure sound signals are processed and analyzed in real time using the air pressure acoustic signal processing and analysis module. The current air pressure state is judged and evaluated through the decision module, and a pressure relief command is sent to avoid over-compression.

[0004] The oil-free and water-free vacuum pump device with automatic exhaust function based on acoustic emission of the present invention is characterized by comprising a hardware system and a software system. The hardware system comprises an air filter, a vacuum pump main unit, an acoustic detection device and a pressure relief device; the air filter comprises an air purifier and an air suction capacity control valve; the vacuum pump main unit comprises a pump body and an electric motor, and a pair of screw rotors meshing with each other and rotating synchronously in opposite directions are arranged in the pump body; the acoustic monitoring device comprises a first acoustic sensor, a second acoustic sensor, a third acoustic sensor, a signal collector and a signal processor; the pressure relief device comprises a first pressure relief hole, a second pressure relief hole, a third pressure relief hole, a pressure relief chamber, a pressure relief pipe, a first automatic pressure relief valve, a second automatic pressure relief valve and a third automatic pressure relief valve. The outer wall of the air inlet magnetically attracts the first acoustic sensor, and the outer wall of the exhaust port magnetically attracts the second acoustic sensor; the pump body is provided with a first pressure relief hole at the air inlet, and a second pressure relief hole at the exhaust port; the first pressure relief hole is provided with a first automatic pressure relief valve, and the second pressure relief hole is provided with a second automatic pressure relief valve; a pressure relief cavity is provided outside the pump body, and the inner cavity of the pump body is connected to the pressure relief cavity outside the pump body through the third pressure relief hole; the pressure relief cavity is connected to a pressure relief pipe, and a third automatic pressure relief valve is provided at the end of the pressure relief pipe, and the pressure relief cavity is connected to the atmosphere outside the pump body through the pressure relief pipe and the third automatic pressure relief valve. The acoustic signal acquisition module is used for the air pressure sound signal transmitted by the acoustic sensor; the air pressure acoustic signal processing and analysis module is used for filtering and feature extraction of the air pressure sound signal; the decision module is used to compare the relationship between the characteristic value of the air pressure sound signal monitored in real time and the threshold value of the preset critical characteristic value of the air pressure sound signal, judge and evaluate the current air pressure state, and issue a deflation instruction; the functional module is used for motor matching power optimization and screw rotor wear state monitoring and analysis in the vacuum pump host. The air pressure acoustic signal processing and analysis module uses the built-in signal processing functions and statistical functions of MATLAB, combined with a custom calculation method, to filter the real-time monitored air pressure sound signal and extract the eigenvalue b value; the eigenvalue threshold in the decision module obtains the air pressure-eigenvalue function relationship by fitting the eigenvalue b value of the air pressure sound signal corresponding to different vacuum pump pressures.

[0005] The oil-free and water-free vacuum pump device with automatic exhaust function based on acoustic emission of the present invention can realize the automatic exhaust function through the following steps:

[0006] (1) Turn on the vacuum pump main motor, and the external gas enters the vacuum pump main body through the air inlet after being purified by the air purifier. It is then compressed by the screw rotors that mesh with each other and rotate synchronously in the opposite direction to form compressed gas for external pressure supply.

[0007] (2) The first acoustic sensor monitors the first air pressure sound signal at the air inlet in real time; the second acoustic sensor monitors the second air pressure sound signal at the exhaust port in real time; the third acoustic sensor monitors the third air pressure sound signal in the inner cavity of the pump body in real time; the air pressure sound signal is transmitted to the air pressure acoustic signal processing and analysis module through the acoustic signal acquisition module to filter the air pressure sound signal and extract the characteristic value b.

[0008] (3) The decision module compares the monitored air pressure sound signal characteristic value with the preset air pressure sound signal critical characteristic value threshold in real time according to the air pressure-characteristic value b value function relationship, judges and evaluates the current air pressure state, and issues a pressure relief command. 1 , the decision module issues a pressure relief command to the automatic pressure relief valve 1 to continuously release pressure; when the characteristic value b of the first air pressure sound signal at the air inlet is greater than the critical value b 1 , the decision module issues a stop pressure relief command to the first automatic pressure relief valve, and the automatic pressure relief valve 1 ends the pressure relief action. When the characteristic value b of the second air pressure sound signal at the exhaust port is less than the critical value b 2 , the decision module issues a pressure relief command to the second automatic pressure relief valve for continuous pressure relief; when the characteristic value b of the second air pressure sound signal at the exhaust port is greater than the critical value b 2 , the decision module issues a stop pressure relief command to the second automatic pressure relief valve, and the second automatic pressure relief valve ends the pressure relief action. When the characteristic value b of the third air pressure sound signal in the pump body cavity exceeds the critical value b 3 , the decision module issues a pressure relief command to the third automatic pressure relief valve to continuously release pressure; the characteristic value b of the third air pressure sound signal is greater than the critical value b 3 , the decision module issues a stop pressure relief instruction to the third automatic pressure relief valve, and the third automatic pressure relief valve ends the pressure relief action.

[0009] The beneficial effects of the present invention are: 1. The oil-free and water-free vacuum pump device with automatic exhaust function based on acoustic emission described in the present invention monitors and analyzes the air pressure sound signals in the air inlet, exhaust port and pump chamber in real time based on acoustic holography and acoustic emission technology, and judges and evaluates the air pressure state in real time through the decision-making module, and adjusts the air pressure in the air inlet, exhaust port and pump chamber to avoid over-compression. 2. Utilize the functional module to optimize the motor power-working pressure matching relationship and select the motor model by analyzing the air pressure sound signal. 3. Through the functional module, analyze the wear state of the screw rotor, control the working condition of the vacuum pump, avoid excessive wear of the screw, and improve the efficient, stable and safe operation performance of the oil-free and water-free vacuum pump. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 The present invention is a schematic structural diagram of an oil-free and water-free vacuum pump device with automatic exhaust function based on acoustic emission.

[0011] Figure 2 This is a distribution diagram of the characteristic value b of the air pressure sound signal when the pump body cavity is overpressured and under normal pressure in Example 1.

[0012] Figure 3 This is a distribution diagram of the characteristic value b of the air pressure sound signal when the screw rotor is over-worn in Example 2.

[0013] In the figure: air purifier 101, intake capacity control valve 102, pump body 201, motor 202, pump body air inlet 203, exhaust port 204, first acoustic sensor 301, second acoustic sensor 302, third acoustic sensor 303, signal collector 304 and signal processor 305, first pressure relief hole 401, second pressure relief hole 402, third pressure relief hole 403, pressure relief chamber 404, pressure relief pipe 405, first automatic pressure relief valve 406, second automatic pressure relief valve 407, third automatic pressure relief valve 408. DETAILED DESCRIPTION

[0014] Embodiment 1

[0015] (1) The air inlet pressure is set to 1 bar, and the critical characteristic value of the air pressure sound signal is b 1 is 0.863; the exhaust pressure is set to 18.5 bar, and the critical characteristic value b of the air pressure sound signal 2 is 0.397; the pressure in the pump cavity is set to 18 bar, and the critical characteristic value of the air pressure sound signal b 3 is 0.375;

[0016] (2) Turn on the vacuum pump main motor, and the external gas enters the vacuum pump main pump body through the air inlet after being purified by the air purifier. It is then compressed by the screw rotors that mesh with each other and rotate synchronously in opposite directions to form compressed gas for external pressure supply.

[0017] (3) The first acoustic sensor monitors the first air pressure sound signal at the air inlet in real time; the second acoustic sensor monitors the second air pressure sound signal at the exhaust port in real time; the third acoustic sensor monitors the third air pressure sound signal in the inner cavity of the pump body in real time; the air pressure sound signal is transmitted to the air pressure acoustic signal processing and analysis module through the acoustic signal acquisition module to filter the air pressure sound signal and extract the characteristic value b.

[0018] (4) When the characteristic value b of the first air pressure sound signal at the air inlet is lower than the critical value 0.863, the decision module issues a pressure relief command to the first automatic pressure relief valve for continuous pressure relief; when the characteristic value b of the third air pressure sound signal is higher than the critical value 0.863, the decision module issues a stop pressure relief command to the first automatic pressure relief valve, and the first automatic pressure relief valve ends the pressure relief action, making the air pressure at the air inlet less than 1 bar.

[0019] (5) When the characteristic value b of the second air pressure sound signal at the exhaust port is lower than the critical value of 0.397, the decision module issues a pressure relief command to the second automatic pressure relief valve for continuous pressure relief; when the characteristic value b of the second air pressure sound signal is higher than the critical value of 0.397, the decision module issues a stop pressure relief command to the second automatic pressure relief valve, and the second automatic pressure relief valve ends the pressure relief action, making the exhaust port pressure less than 18.5 bar.

[0020] (6) When the characteristic value b of the third air pressure sound signal in the pump body cavity is lower than the critical value of 0.375, the decision module issues a pressure relief command to the third automatic pressure relief valve for continuous pressure relief; when the characteristic value b of the third air pressure sound signal is higher than the critical value of 0.375, the decision module issues a stop pressure relief command to the third automatic pressure relief valve, and the third automatic pressure relief valve ends the pressure relief action, so that the pressure in the vacuum pump cavity is stabilized at 18 bar.

[0021] Embodiment 2

[0022] (1) The inlet pressure is set to 1 bar, the exhaust pressure is set to 16.5 bar, and the pressure in the pump cavity is set to 16 bar. The corresponding air pressure sound signal characteristic value under the condition of excessive wear of the screw rotor is [0.400, 0.426].

[0023] (2) Turn on the vacuum pump main motor, and the external gas enters the vacuum pump main body through the air inlet after being purified by the air purifier, and is then compressed by the screw rotors that mesh with each other and rotate synchronously in the opposite direction to form compressed gas, which is then supplied to the outside through the exhaust port.

[0024] (3) The first acoustic sensor monitors the first air pressure sound signal at the air inlet in real time; the second acoustic sensor monitors the second air pressure sound signal at the exhaust port in real time; the third acoustic sensor monitors the third air pressure sound signal in the inner cavity of the pump body in real time; the air pressure sound signal is transmitted to the air pressure acoustic signal processing and analysis module through the acoustic signal acquisition module to filter the air pressure sound signal and extract the characteristic value b.

[0025] (4) When the characteristic value b of the third air pressure sound signal in the pump body cavity is between [0.400, 0.426], it indicates that the screw rotor of the vacuum pump is excessively worn, and a warning signal is generated to remind you to replace the screw rotor.

Claims

1. An oil-free and water-free vacuum pump device with automatic exhaust function based on acoustic emission, characterized in that: Including hardware system and software system; The hardware system comprises an air filter (1), a vacuum pump main unit (2), an acoustic detection device (3) and a pressure relief device (4); the air filter (1) comprises an air purifier (101) and an air intake capacity control valve (102); the vacuum pump main unit (2) comprises a pump body (201) and an electric motor (202), wherein the pump body comprises a pair of screw rotors which mesh with each other and rotate synchronously in opposite directions; the acoustic monitoring device (3) comprises a first acoustic sensor (301), a second acoustic sensor (302), a third acoustic sensor (303), a signal collector (304) and a signal processor (305); the pressure relief device (4) comprises a first pressure relief hole (401), a second pressure relief hole (402), a third pressure relief hole (403), a pressure relief chamber (404), a pressure relief pipe (405), a first automatic pressure relief valve (406), a second automatic pressure relief valve (407) and a third automatic pressure relief valve (408); 08), the outer wall of the air inlet (203) magnetically attracts a first acoustic sensor (301), and the outer wall of the exhaust port (204) magnetically attracts a second acoustic sensor (302); a first pressure relief hole (401) is arranged at the position of the air inlet (203) of the pump body, and a second pressure relief hole (402) is arranged at the position of the exhaust port (204); the first pressure relief hole (401) is provided with a first automatic pressure relief valve (406), and the second pressure relief hole (402) is provided with a second automatic pressure relief valve (406). valve (407); a pressure relief chamber (404) is arranged outside the pump body (201); the inner chamber of the pump body is communicated with the pressure relief chamber (404) outside the pump body through a third pressure relief hole (403); the pressure relief chamber (404) is externally connected to a pressure relief pipe (405); a third automatic pressure relief valve (408) is arranged at the end of the pressure relief pipe (405); the pressure relief chamber (404) is communicated with the atmosphere outside the pump body (201) through the pressure relief pipe (405) and the third automatic pressure relief valve (408); The software system includes an acoustic signal acquisition module, an acoustic signal processing and analysis module, a decision module, and a functional module; the vacuum pump host is used to compress air; the acoustic detection device is used to detect, collect, process and analyze the air pressure sound signal at the air inlet, exhaust port and vacuum pump cavity of the vacuum pump, the acoustic sensor detects the air pressure sound signal, the signal collector collects the air pressure sound signal, and transmits it to the data processor through the data interface; The acoustic signal acquisition module is used for the air pressure sound signal transmitted by the acoustic sensor; the air pressure acoustic signal processing and analysis module is used for filtering and feature extraction of the air pressure sound signal; The decision module is used to compare the relationship between the real-time monitored air pressure sound signal characteristic value and the preset air pressure sound signal critical characteristic value threshold, judge and evaluate the current air pressure state, and issue a deflation instruction; the functional module is used to optimize the motor matching power in the vacuum pump host and monitor and analyze the wear status of the screw rotor.

2. According to claim 1, an oil-free and water-free vacuum pump device with automatic exhaust function based on acoustic emission is characterized in that: The air pressure acoustic signal processing and analysis module uses the built-in signal processing functions and statistical functions of MATLAB, combined with a custom calculation method, to filter the real-time monitored air pressure sound signal and extract the characteristic value b.

3. The waterless vacuum pump device with automatic exhaust function based on acoustic emission according to claim 1, characterized in that: The characteristic value threshold in the decision module is obtained by fitting the characteristic value b of the air pressure sound signal corresponding to different vacuum pump pressures to obtain the air pressure-characteristic value function relationship.

4. The waterless vacuum pump device with automatic exhaust function based on acoustic emission according to claim 1 is characterized in that: The device realizes the automatic exhaust function through the following steps: (1) The vacuum pump main engine motor (202) is turned on, and the external air is purified by the air purifier (101) and enters the vacuum pump main engine pump body (201) through the air inlet (203), and is then compressed by the screw rotors that mesh with each other and rotate synchronously in opposite directions to form compressed gas for external pressure supply; (2) The first acoustic sensor (301) monitors the first air pressure sound signal of the air inlet (203) in real time; the second acoustic sensor (302) monitors the second air pressure sound signal of the exhaust port (204) in real time; the third acoustic sensor (303) monitors the third air pressure sound signal of the inner cavity of the pump body (201) in real time; the air pressure sound signal is transmitted to the air pressure acoustic signal processing and analysis module via the acoustic signal acquisition module to perform filtering processing on the air pressure sound signal and extract the characteristic value b; (3) The decision module compares the monitored air pressure sound signal characteristic value with the preset air pressure sound signal critical characteristic value threshold in real time according to the air pressure-characteristic value b value function relationship, judges and evaluates the current air pressure state, and issues a pressure relief instruction; when the characteristic value b of the first air pressure sound signal at the air inlet (203) is less than the critical value b1, the decision module issues a pressure relief instruction to the first automatic pressure relief valve (406) to continuously relieve pressure; when the characteristic value b of the first air pressure sound signal at the air inlet (203) is greater than the critical value b1, the decision module issues a stop pressure relief instruction to the first automatic pressure relief valve (406), and the first automatic pressure relief valve (406) ends the pressure relief action; when the characteristic value b of the second air pressure sound signal at the exhaust port (204) is less than the critical value b2, the decision module issues a pressure relief instruction to the second automatic pressure relief valve (407) to continuously relieve pressure; When the characteristic value b of the second air pressure sound signal at the exhaust port (204) is greater than the critical value b2, the decision module issues a stop pressure relief instruction to the second automatic pressure relief valve (407), and the second automatic pressure relief valve (407) ends the pressure relief action; when the characteristic value b of the third air pressure sound signal in the cavity of the pump body (201) is less than the critical value b3, the decision module issues a pressure relief instruction to the third automatic pressure relief valve (408) to continue pressure relief; When the characteristic value b of the third air pressure sound signal is greater than the critical value b3, the decision module issues a stop pressure relief instruction to the third automatic pressure relief valve (408), and the third automatic pressure relief valve (408) ends the pressure relief action.

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