CN110374857B - Oil pressure and air pressure monitoring device and method for diaphragm compressor - Google Patents
Oil pressure and air pressure monitoring device and method for diaphragm compressor Download PDFInfo
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- CN110374857B CN110374857B CN201910615493.2A CN201910615493A CN110374857B CN 110374857 B CN110374857 B CN 110374857B CN 201910615493 A CN201910615493 A CN 201910615493A CN 110374857 B CN110374857 B CN 110374857B
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
- F04B45/00—Pumps or pumping installations having flexible working members and specially adapted for elastic fluids
- F04B45/04—Pumps or pumping installations having flexible working members and specially adapted for elastic fluids having plate-like flexible members, e.g. diaphragms
- F04B45/053—Pumps having fluid drive
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
- F04B51/00—Testing machines, pumps, or pumping installations
Abstract
The application belongs to the technical field of compressors, and particularly relates to a device and a method for monitoring oil pressure and air pressure of a diaphragm compressor. Because the diaphragm compressor can be operated at a high pressure ratio and a wide pressure range, the highest exhaust pressure can reach 300MPa, and if a method of processing a pressure measuring hole on a cylinder body is adopted, the strength of the cylinder is influenced, and leakage can be caused, so that potential safety hazards are brought. The application provides a device for monitoring oil pressure and air pressure of a diaphragm compressor, which comprises an air cylinder and a strain gage circuit, wherein the air cylinder comprises a cylinder head; the strain gauge circuit comprises a strain gauge component and a bridge circuit which are connected with each other, and the strain gauge component is arranged on the cylinder head. By arranging the strain gauge component on the cylinder head and connecting the strain gauge component with the bridge circuit, the sensitivity of the strain gauge component is improved, and the input and the output are in a linear relation. The device is safe and reliable, has no damage to the diaphragm compressor, and can monitor the hydraulic pressure in the oil side cylinder head and the air pressure in the air side cylinder head of the diaphragm compressor particularly under the high-pressure working condition.
Description
Technical Field
The application belongs to the technical field of compressors, and particularly relates to a device and a method for monitoring oil pressure and air pressure of a diaphragm compressor.
Background
The diaphragm compressor is a special gas compression device without leakage of a compression cavity. Because the sealing performance provided by the gas compressor is good, the pressure range is wide, and the compression ratio is large, the gas compressor is widely applied to compressing and conveying various high-purity gases, precious rare gases, toxic and harmful gases and corrosive gases in the fields of hydrogenation stations and petrochemical industry. In the diaphragm compressor, working oil in an oil cavity of a cylinder is pushed through a piston, and then a diaphragm is pushed to reciprocate in the diaphragm cavity, so that the working volume of an air cavity is changed, and a leakage-free periodic working process is realized under the coordination of an air suction valve and an air discharge valve. In a hydraulic oil circulating system of a diaphragm compressor, oil leaked through a hydraulic piston ring is compensated through a compensation loop, and the oil compensation amount is adjusted by installing an oil overflow valve on an oil side cylinder head.
The oil pressure and air pressure change of the diaphragm compressor is the comprehensive reflection of the working performance and the running state of the compressor, and the oil pressure and air pressure change curve of the working process of the diaphragm compressor can reflect the position of a piston, the time of an air suction process, the opening and closing actions of an air suction valve, the opening and closing actions of an exhaust valve, the time of an exhaust process, the action of an oil spill valve and the oil supplementing process, so that the oil pressure and air pressure change curve is the most effective tool for diagnosing the faults of the diaphragm compressor, the dynamic monitoring of the oil pressure of the diaphragm compressor is an effective method for improving the running reliability and safety of equipment, and the monitoring of the running state of the equipment is also a strong demand of designers and users of.
Because the diaphragm compressor can be operated at a high pressure and a wide pressure range, the highest exhaust pressure can reach 300MPa, if a method of processing a pressure measuring hole on a cylinder body is adopted, the hydraulic pressure in the oil side cylinder head and the air pressure in the air side cylinder head of the diaphragm compressor are monitored, the strength of the cylinder is influenced, and leakage can be caused, so that potential safety hazards are brought. .
Disclosure of Invention
1. Technical problem to be solved
Because the diaphragm compressor can be operated at a high pressure ratio and a wide pressure range, the highest exhaust pressure can reach 300MPa, if a method of processing a pressure measuring hole on a cylinder body is adopted, the hydraulic pressure in an oil side cylinder head and the air pressure in an air side cylinder head of the diaphragm compressor are monitored, the strength of the cylinder is influenced, and the problems of leakage and potential safety hazards are caused. The application provides a device and a method for monitoring oil pressure and air pressure of a diaphragm compressor.
2. Technical scheme
In order to achieve the above object, the present application provides a diaphragm compressor oil pressure and air pressure monitoring device, comprising a cylinder and a strain gauge circuit;
the cylinder comprises a cylinder head and an exhaust valve hole, and the exhaust valve hole is arranged on the cylinder head;
the strain gauge circuit comprises a strain gauge component and a bridge circuit which are connected with each other, the strain gauge component comprises a first strain gauge group and a second strain gauge group, the first strain gauge group is arranged on the outer surface of the cylinder head, the second strain gauge group is arranged on the bottom plane of the exhaust valve hole, the first strain gauge group is connected with the bridge circuit, and the second strain gauge group is connected with the bridge circuit.
Optionally, the first strain gauge group includes a first strain gauge and a second strain gauge, and the first strain gauge and the second strain gauge are arranged perpendicular to each other;
the second strain gauge group comprises a third strain gauge and a fourth strain gauge, and the third strain gauge and the fourth strain gauge are perpendicular to each other.
Optionally, the strain gauge assembly further comprises a third strain gauge set and a fourth strain gauge set;
the third strain gage group is arranged on the flange, the flange is arranged on the exhaust pipeline, and the fourth strain gage group is arranged on the flange.
Optionally, the strain gauge assembly is connected to a half bridge circuit.
Optionally, the strain gauge assembly is connected to a full bridge circuit.
Optionally, the strain gauge further comprises a photoelectric sensing unit and a data acquisition unit, wherein the photoelectric sensing unit comprises a flywheel, the flywheel and the photoelectric sensor are correspondingly arranged, the data acquisition unit is connected with the strain gauge assembly, and the data acquisition unit is connected with the photoelectric sensor; the data acquisition unit is connected with the data processing unit.
The application also provides a method for monitoring oil pressure and air pressure of the diaphragm compressor, which comprises the following steps:
step 1, constructing a strain measurement system: selecting the type of a strain gauge according to the size of the cylinder cover, pasting the selected strain gauge, connecting the strain gauge with an electric bridge, and then configuring a data acquisition unit after installing a photoelectric sensor at the flywheel;
and 4, processing the second digital signal according to the starting and stopping time of the complete period to obtain an oil pressure value and an air pressure value.
Optionally, the processing the second digital signal in step 4 includes:
(1) and respectively calculating the strain of the working strain gauge according to the measured voltage data:
wherein theta represents a crank angle, (theta) is strain, E (theta) is an acquired voltage signal, mu is a Poisson's ratio, E is an elastic modulus, and K issIs the sensitivity coefficient of the strain gauge;
(2) calculating oil pressure:
simplifying the cylinder head into a circular flat plate model, calculating the radial stress and the circumferential stress of a strain gage on the outer surface of the cylinder head according to the measured strain, and then carrying out calculation according to the structure of the diaphragm compressor and the boundary condition of a peripheral solid support flat plate with uniformly distributed loads to obtain an oil pressure value;
(3) calculating the air pressure:
and calculating the radial stress and the circumferential stress of the bottom plane of the exhaust valve hole according to the measured strain, and then calculating to obtain an air pressure value.
Optionally, in step 2, the first voltage signal is converted into a first digital signal through filtering, amplifying, conditioning and a/D conversion, and the first digital signal is transmitted to the intelligent terminal for processing, and the second voltage signal is converted into a second digital signal through filtering, amplifying, conditioning and a/D conversion, and the second digital signal is transmitted to the intelligent terminal for processing.
3. Advantageous effects
Compared with the prior art, the diaphragm compressor oil pressure and air pressure monitoring device and method provided by the application have the beneficial effects that:
the application provides a diaphragm compressor oil pressure and pneumatic pressure monitoring devices through setting up strain gage subassembly in gas side cylinder head, is connected strain gage subassembly and bridge circuit, improves strain gage subassembly's sensitivity to make input and output be linear relation. Because the strain gage is pasted to the non-invasive type of gas side cylinder head at diaphragm compressor, set up strain gage subassembly and measure gas side cylinder head and meet an emergency for oil pressure and atmospheric pressure can indirect measurationing, can the harmless safe oil pressure of measuring diaphragm compressor. The diaphragm compressor is not damaged, safe and reliable, and accurate monitoring of oil pressure and gas side pressure can be realized especially under the high-pressure working condition.
Drawings
FIG. 1 is a schematic view of a first configuration of a diaphragm compressor oil pressure and air pressure monitoring apparatus of the present application;
FIG. 2 is a schematic view of a strain gage arrangement of the present application;
FIG. 3 is a schematic diagram of a half-bridge connection of the strain gage of the present application;
FIG. 4 is a schematic illustration of the diaphragm compressor oil pressure and air pressure monitoring apparatus of the present application;
FIG. 5 is a schematic diagram showing a comparison of oil pressure measured by the sensor and oil pressure data measured by the air cylinder head strain gauge;
FIG. 6 is a schematic diagram showing a comparison between the air pressure measured by the sensor and the air pressure measured by the air side cylinder head strain gauge;
in the figure: the device comprises a cylinder head at the air side 1, an exhaust valve hole 2, a first strain gauge 3, a second strain gauge 4, a third strain gauge 5, a fourth strain gauge 6, a signal acquisition unit 7, a flywheel 8, a photoelectric sensor 9 and a data processing unit 10.
Detailed Description
Hereinafter, specific embodiments of the present application will be described in detail with reference to the accompanying drawings, and it will be apparent to those skilled in the art from this detailed description that the present application can be practiced. Features from different embodiments may be combined to yield new embodiments, or certain features may be substituted for certain embodiments to yield yet further preferred embodiments, without departing from the principles of the present application.
A strain gauge is an element for measuring strain that is constituted by a sensitive grid or the like. The working principle of the resistance strain gauge is based on the strain effect, that is, when a conductor or a semiconductor material is mechanically deformed under the action of external force, the resistance value of the conductor or the semiconductor material is correspondingly changed, and the phenomenon is called the strain effect.
The quadrilateral measuring bridge circuit composed of elements such as a resistor, a capacitor, an inductor and the like is called as an electric bridge, and four sides of the electric bridge are bridge arms. As a measuring circuit, a direct current power supply is connected to two ends of one diagonal line of the quadrangle, voltages at two ends of the other diagonal line are led out, and parameters (such as resistance, capacitance and inductance) of the element to be measured can be obtained according to the numerical values of the known elements in the bridge arms by utilizing a bridge balance equation.
Referring to fig. 1 to 6, the application provides a diaphragm compressor oil pressure and air pressure monitoring device, which comprises a cylinder and a strain gauge circuit;
the cylinder comprises a cylinder head 1 and an exhaust valve hole 2, and the exhaust valve hole 2 is arranged on the cylinder head 1;
the strain gauge circuit comprises a strain gauge component and a bridge circuit which are connected with each other, the strain gauge component comprises a first strain gauge group and a second strain gauge group, the first strain gauge group is arranged on the outer surface of the cylinder head 1, the second strain gauge group is arranged on the bottom plane of the exhaust valve hole 2, the first strain gauge group is connected with the bridge circuit, and the second strain gauge group is connected with the bridge circuit.
The cylinder head 1 is an air side cylinder head or an oil side cylinder head, and the strain gauge assembly is adhered to the air side cylinder head or the oil side cylinder head through an adhesive. The structural member attached with the strain gauge assembly is always in a certain temperature field, if the linear expansion coefficient of the strain gauge sensitive grid is not equal to that of the construction material, when the temperature changes, the sensitive grid receives additional tension (or compression) due to unequal extension (or compression) amounts of the sensitive grid and the structural member, the resistance of the sensitive grid changes, and inaccurate measurement is caused, which is a temperature effect.
A strain gage assembly is a sensor whose intrinsic resistance changes with changes in stress. Almost all the strain gauge assemblies 2 have a low sensitivity, and the sensitivity can be multiplied by the bridge circuit, and the input and output are linear. The change of the strain gauge component is detected by using the bridge circuit, and the strain gauge also has the advantages of extremely low passing current and low self-heating of the strain gauge. Therefore, bridge circuits are often used in strain gage sensor applications. The bridge circuit comprises a quarter bridge connection mode, a half bridge connection mode and a full bridge connection mode. The lead of the strain gauge is a silver-coated copper wire with the diameter of 25mm (the diameter is 0.12 mm-0.16 mm), the diameters of piston rods of different units are different, and the sizes of the selected strain gauge can also be different. That is, the strain gauge may be selected according to actual needs.
The first strain gauge group is arranged on the outer surface of the cylinder head 1, namely, the working plate group is pasted on the outer surface of the cylinder head on the air side, because the oil pressure and the air pressure have the accompanying relation and are almost consistent when the diaphragm is not in contact with the cylinder head on the air side, the strain of the cylinder head 1 caused by the air pressure is consistent with the strain of the cylinder head 1 caused by the oil pressure, when the diaphragm is in contact with the cylinder head on the air side, the pressure measured by oil can be directly exerted on the cylinder head on the air side through the diaphragm, and the oil pressure in the cylinder can be monitored through the first strain gauge group pasted on the cylinder head 1 on the air.
The air pressure in the cylinder is monitored by a second strain gauge group, namely a working plate group, which is adhered to the bottom plane of the exhaust valve hole 2.
The positions of the strain gauges attached to the air side cylinder head are as follows: the front surface of the air side cylinder head is pasted in a half-surface area without the air suction valve hole along the extension line of the connection line of the circle centers of the air suction valve hole and the air exhaust valve hole;
the strain gauge on the gas side cylinder head or the oil side cylinder head measures the oil pressure, and the strain gauge on the exhaust valve hole measures the air pressure.
Further, the first strain gauge group comprises a first strain gauge 3 and a second strain gauge 4, and the first strain gauge 3 and the second strain gauge 4 are arranged perpendicular to each other;
the second strain gauge group comprises a third strain gauge 5 and a fourth strain gauge 6, and the third strain gauge 5 and the fourth strain gauge 6 are perpendicular to each other.
Two mutually perpendicular working pieces are adopted and connected into the half-bridge circuit, and the working pieces are connected with one bridge arm of the half-bridge circuit.
Further, the strain gauge assembly further comprises a third strain gauge set and a fourth strain gauge set;
the third strain gage group is arranged on the flange, the flange is arranged on the exhaust pipeline, and the fourth strain gage group is arranged on the flange.
The first strain gauge is pasted along the radial direction of the outer surface of the cylinder head at the air side, and the second strain gauge is pasted along the circumferential direction of the outer surface of the cylinder head at the air side; the third strain gauge is pasted along the radial direction of the bottom plane of the exhaust valve hole 2, and the fourth strain gauge is pasted along the circumferential direction of the bottom plane of the exhaust valve hole 2;
in the scheme, two working sheets are vertically arranged on the outer surface of the cylinder head 1 on the gas side, two working sheets are vertically arranged on the bottom plane of the exhaust valve hole 2, 4 compensating sheets, namely a fifth strain gauge group and a sixth strain gauge group, are arranged on a flange of an exhaust pipeline, the influence of the temperature of a lead on a measurement result is eliminated by sticking the compensating sheets, and the compensating sheets can also be arranged in other places which can ensure that the temperature of the compensating sheets is close to the temperature of a cylinder cover and is not stressed.
Two strain gauges are respectively stuck at two positions (the outer surface of the cylinder head 1 and the bottom surface of the exhaust valve hole 2), the four strain gauges are working gauges and are used for measuring circumferential and radial strains of the stuck position (the circumferential and radial strains in 2 directions exist because of a circular flat plate), and oil pressure and air pressure can be calculated according to the radial and circumferential strains. When the working sheet is adhered to the cylinder body and the bottom surfaces of the cylinder head 1 and the exhaust valve hole 2 deform, the strain gauge adhered to the position is stretched, so that the resistance of the working sheet changes, and the change of the resistance causes the change of the output voltage of the bridge circuit.
Further, the strain gauge assembly is connected to a half bridge circuit. A bridge circuit is constructed by a half-bridge method, so that the output of the strain gauge is increased and the temperature influence of a lead is eliminated. As in the half-bridge method in fig. 3, the working piece and the temperature compensation piece are respectively connected to two adjacent bridge arms, and the other two bridge arms are connected to the fixed resistor.
Further, the strain gauge assembly is connected with a full bridge circuit.
The pasting method of the strain gauge comprises 3 types of quarter-bridge, half-bridge and full-bridge, which are reasonable. And the half bridge is connected with only 2 strain gages, and the full bridge is connected with 4 strain gages.
Further, the strain gauge further comprises a photoelectric sensing unit and a data acquisition unit 7, wherein the photoelectric sensing unit comprises a flywheel 8, the flywheel 8 and a photoelectric sensor 9 are correspondingly arranged, the data acquisition unit 7 is connected with the strain gauge component, and the data acquisition unit 7 is connected with the photoelectric sensor 9; the data acquisition unit 7 is connected with a data processing unit 10.
The detection method of the piston dead point signal is more, hall type and photoelectric type sensors are commonly used in the compressor technology, the transmitting end of the sensor is generally arranged on the flywheel 8, the photoelectric sensor 9 is generally in a reflection type, the installation position of a probe of the photoelectric sensor 9 needs to be accurately positioned, namely, the flywheel 8 is rotated to enable the piston to be respectively positioned at an inner dead point and an outer dead point, and then the probe is aligned to a transmitting point (magnetic steel, an iron block or a light reflecting strip).
The flywheel 8 rotates around a vertical axis, the jigger finds the position of the piston moving to the top dead center as the reference of phase reference, a mark is made at any position of the flywheel 8 at the moment, and a light spot sensor is arranged on the frame to align the mark. Under normal conditions, the photoelectric sensor 9 acquires a stable signal, when a mark is transferred to the photoelectric sensor 9, an impact signal appears as a period starting position, and one period is formed between every two continuous impact signals.
The photoelectric sensing unit is used for obtaining a periodic signal so as to judge a complete period. A photoelectric sensor 9 is arranged at the flywheel 8, and the initial value 0 of the crank angle theta of the compressor is determined according to the obtained outer dead center signal; the analog signal output by the photoelectric sensor 9 is converted into the finally required digital signal through the data acquisition unit 7 and stored for subsequent analysis and processing.
Data acquisition here used are strain acquisition cards NI9237, NI9205 and acquisition chassis cDAQ-9185 from National Instruments (NI) Inc., and data acquisition was performed by writing LabVIEW program.
The data processing unit is an intelligent terminal. The intelligent terminal herein refers to a device capable of performing calculation analysis on data, such as a computer, where the computer needs to run a data acquisition program, control sampling and displaying of signals, such as setting parameters of sampling frequency and sample storage length, in addition to storing data. The data acquisition system realizes a series of functions of signal filtering, amplification, conditioning and A/D conversion. And the computer displays the acquired stop point signal of the photoelectric sensor 9 and the output voltage signal of the strain gauge circuit. The display may be monitored in real time.
The data acquisition unit 7 comprises an acquisition card and a signal conditioning module. And setting data sampling frequency and a corresponding acquisition channel.
The data acquisition unit 7 realizes a series of functions of signal filtering, amplification, conditioning and A/D conversion.
The application also provides a method for monitoring oil pressure and air pressure of the diaphragm compressor, which comprises the following steps:
step 1, constructing a strain measurement system: selecting the type of a strain gauge according to the size of the cylinder cover, pasting the selected strain gauge, connecting the strain gauge with an electric bridge, and then configuring a data acquisition unit after installing a photoelectric sensor at the flywheel;
and 4, processing the second digital signal according to the starting and stopping time of the complete period to obtain an oil pressure value and an air pressure value.
Further, the processing the second digital signal in step 4 includes:
(1) and respectively calculating the strain of the working strain gauge according to the measured voltage data:
wherein theta represents a crank angle (0-360 degrees), theta represents strain, E (theta) represents an acquired voltage signal, mu represents a Poisson's ratio, E represents an elastic modulus, and K representssIs the sensitivity coefficient of the strain gauge; the strain of 4 working pieces is calculated firstly;
(2) calculating oil pressure:
simplifying the cylinder head into a circular flat plate model, calculating the radial stress and the circumferential stress of a strain gage on the outer surface of the cylinder head according to the measured strain, and then carrying out calculation according to the structure of the diaphragm compressor and the boundary condition of a peripheral solid support flat plate with uniformly distributed loads to obtain an oil pressure value;
(3) calculating the air pressure:
and calculating the radial stress and the circumferential stress of the bottom plane of the exhaust valve hole according to the measured strain, and then calculating to obtain an air pressure value.
Furthermore, in the step 1, the first voltage signal is converted into a first digital signal through filtering, amplifying, conditioning and a/D conversion, and the first digital signal is transmitted to the intelligent terminal for processing, and the second voltage signal is converted into a second digital signal through filtering, amplifying, conditioning and a/D conversion, and the second digital signal is transmitted to the intelligent terminal for processing.
And in the specific data acquisition process, analog signals output by the strain gauge and the photoelectric sensor are converted into finally required digital signals through a data acquisition system and are stored in a computer hard disk for subsequent analysis and processing.
The calculation is carried out by a computer according to a formula, and the realization mode can be software programming or excel.
And calculating by using a formula according to the acquired data, wherein the formula is used as a computer, and a LabVIEW program is compiled for calculation.
Use the foil gage in this application to monitor the strain of diaphragm compressor gas side cylinder end 1 surface and 2 bottom surface platforms departments of exhaust valve hole, including eight foil gages, four work pieces, four compensation pieces. And adhering work strain gauges Rw1 and Rw2 on the outer surface of the air side cylinder head 1, wherein Rw1 is adhered along the radial direction, and Rw2 is adhered along the circumferential direction. And adhering work strain gauges Rw3 and Rw4 at the bottom end platform of the exhaust valve hole 2 of the cylinder head at the air side, wherein Rw3 is adhered along the radial direction, and Rw4 is adhered along the circumferential direction. For the compensator: the influence of temperature on the measurement result is eliminated by pasting the compensating plate, and the compensating plate is pasted on a flange of the exhaust pipeline (or other places which can ensure that the temperature of the compensating plate is close to the temperature of the cylinder cover and is not stressed). A bridge circuit is constructed by a half-bridge method, so that the output of the strain gauge is increased and the temperature influence of a lead is eliminated.
The application provides a diaphragm compressor oil pressure monitoring devices through setting up the foil gage subassembly in gas side cylinder end, is connected the foil gage subassembly with bridge circuit, improves the sensitivity of foil gage subassembly to make input and output be linear relation. Because the strain gage is pasted to the non-invasive type of gas side cylinder head at diaphragm compressor, set up strain gage subassembly and measure gas side cylinder head and meet an emergency for oil pressure and atmospheric pressure can indirect measurationing, can harmless safe measurement diaphragm compressor oil pressure and atmospheric pressure. The method is safe and reliable, has no damage to the diaphragm compressor, and can realize accurate monitoring of the oil side pressure and the gas side pressure particularly under the high-pressure working condition.
The first and second structures are the same in this application only for the purpose of distinguishing the strain gauges.
Although the present application has been described above with reference to specific embodiments, those skilled in the art will recognize that many changes may be made in the configuration and details of the present application within the principles and scope of the present application. The scope of protection of the application is determined by the appended claims, and all changes that come within the meaning and range of equivalency of the technical features are intended to be embraced therein.
Claims (8)
1. The utility model provides a diaphragm compressor oil pressure and atmospheric pressure monitoring devices which characterized in that: the device comprises a cylinder and a strain gauge circuit;
the cylinder comprises a cylinder head (1) and an exhaust valve hole (2), and the exhaust valve hole (2) is arranged on the cylinder head (1);
the strain gauge circuit comprises a strain gauge component and a bridge circuit which are connected with each other, the strain gauge component comprises a first strain gauge group and a second strain gauge group, the first strain gauge group is arranged on the outer surface of the cylinder head (1), the second strain gauge group is arranged on the bottom plane of the exhaust valve hole (2), the first strain gauge group is connected with the bridge circuit, and the second strain gauge group is connected with the bridge circuit; the strain gauge assembly is characterized by further comprising a photoelectric sensing unit and a data acquisition unit (7), wherein the photoelectric sensing unit comprises a flywheel (8), the flywheel (8) and a photoelectric sensor (9) are correspondingly arranged, the data acquisition unit (7) is connected with the strain gauge assembly, and the data acquisition unit (7) is connected with the photoelectric sensor (9); the data acquisition unit (7) is connected with the data processing unit (10).
2. The diaphragm compressor oil pressure and air pressure monitoring device of claim 1, wherein: the first strain gage group comprises a first strain gage (3) and a second strain gage (4), and the first strain gage (3) and the second strain gage (4) are arranged vertically to each other;
the second strain gauge group comprises a third strain gauge (5) and a fourth strain gauge (6), and the third strain gauge (5) and the fourth strain gauge (6) are perpendicular to each other.
3. The diaphragm compressor oil pressure and air pressure monitoring device of claim 1, wherein: the strain gauge component further comprises a third strain gauge group and a fourth strain gauge group;
the third strain gage group is arranged on the flange, the flange is arranged on the exhaust pipeline, and the fourth strain gage group is arranged on the flange.
4. The diaphragm compressor oil pressure and air pressure monitoring device of claim 1, wherein: the bridge circuit comprises a half-bridge circuit, and the strain gauge component is connected with the half-bridge circuit.
5. The diaphragm compressor oil pressure and air pressure monitoring device of claim 1, wherein: the bridge circuit comprises a full bridge circuit, and the strain gauge component is connected with the full bridge circuit.
6. A method for monitoring oil pressure and air pressure of a diaphragm compressor is characterized by comprising the following steps: the method comprises the following steps:
step 1, constructing a strain measurement system: selecting the type of a strain gauge according to the size of the cylinder cover, pasting the selected strain gauge, connecting the strain gauge with an electric bridge, and then configuring a data acquisition unit after installing a photoelectric sensor at the flywheel;
step 2, signal acquisition: synchronously acquiring a first voltage signal and a second voltage signal output by the strain gauge circuit through the data acquisition unit, simultaneously converting the acquired first voltage signal into a first digital signal for storage, and converting the acquired second voltage signal into a second digital signal for storage;
step 3, judging the start-stop time of a complete period according to the first digital signal;
and 4, processing the second digital signal according to the starting and stopping time of the complete period to obtain an oil pressure value and an air pressure value.
7. The method of monitoring oil pressure and gas pressure of a diaphragm compressor of claim 6, wherein: the processing the second digital signal in the step 4 includes:
(1) and respectively calculating the strain of the working strain gauge according to the measured voltage data:
wherein theta represents a crank angle, (theta) is strain, E (theta) is an acquired voltage signal, mu is a Poisson's ratio, E is an elastic modulus, and K issIs the sensitivity coefficient of the strain gauge;
(2) calculating oil pressure:
simplifying the cylinder head into a circular flat plate model, calculating the radial stress and the circumferential stress of a strain gage on the outer surface of the cylinder head according to the measured strain, and then carrying out calculation according to the structure of the diaphragm compressor and the boundary condition of a peripheral solid support flat plate with uniformly distributed loads to obtain an oil pressure value;
(3) calculating the air pressure:
and calculating the radial stress and the circumferential stress of the bottom plane of the exhaust valve hole according to the measured strain, and then calculating to obtain an air pressure value.
8. The method of monitoring oil pressure and gas pressure of a diaphragm compressor of claim 7, wherein: in the step 2, the first voltage signal is converted into a first digital signal through filtering, amplifying, conditioning and A/D conversion and is transmitted to the intelligent terminal for processing, and the second voltage signal is converted into a second digital signal through filtering, amplifying, conditioning and A/D conversion and is transmitted to the intelligent terminal for processing.
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| CN111927749B (en) * | 2020-07-14 | 2021-08-10 | 西安交通大学 | Diaphragm compressor air pressure nondestructive monitoring system and method |
| CN111927750B (en) * | 2020-07-14 | 2021-12-28 | 西安交通大学 | Nondestructive monitoring system and method for diaphragm of diaphragm compressor |
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| CN116591949B (en) * | 2023-07-18 | 2023-10-03 | 合肥通用机械研究院有限公司 | Non-invasive type air pressure monitoring device and monitoring method for high-pressure diaphragm compressor |
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