CN109357730A - A kind of liquid level detection system based on Electromagnetic Wave Method - Google Patents
A kind of liquid level detection system based on Electromagnetic Wave Method Download PDFInfo
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- CN109357730A CN109357730A CN201811236757.5A CN201811236757A CN109357730A CN 109357730 A CN109357730 A CN 109357730A CN 201811236757 A CN201811236757 A CN 201811236757A CN 109357730 A CN109357730 A CN 109357730A
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- 239000007788 liquid Substances 0.000 title claims abstract description 243
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- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims abstract description 396
- 229910052757 nitrogen Inorganic materials 0.000 claims abstract description 198
- 238000003860 storage Methods 0.000 claims abstract description 32
- 239000007789 gas Substances 0.000 claims description 7
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- 210000004291 uterus Anatomy 0.000 claims description 2
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- 238000010586 diagram Methods 0.000 description 3
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- 235000003140 Panax quinquefolius Nutrition 0.000 description 2
- 210000001367 artery Anatomy 0.000 description 2
- 230000003111 delayed effect Effects 0.000 description 2
- 238000001704 evaporation Methods 0.000 description 2
- 230000008020 evaporation Effects 0.000 description 2
- 235000008434 ginseng Nutrition 0.000 description 2
- 238000001802 infusion Methods 0.000 description 2
- 238000009434 installation Methods 0.000 description 2
- 238000005339 levitation Methods 0.000 description 2
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- 230000000644 propagated effect Effects 0.000 description 2
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Classifications
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
- G01F23/00—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm
- G01F23/22—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm by measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water
- G01F23/28—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm by measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water by measuring the variations of parameters of electromagnetic or acoustic waves applied directly to the liquid or fluent solid material
- G01F23/284—Electromagnetic waves
- G01F23/292—Light, e.g. infrared or ultraviolet
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
- G01F23/00—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm
- G01F23/0007—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm for discrete indicating and measuring
- G01F23/0015—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm for discrete indicating and measuring with a whistle or other sonorous signal
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- Measurement Of Levels Of Liquids Or Fluent Solid Materials (AREA)
Abstract
The present invention provides a kind of liquid level detection system based on Electromagnetic Wave Method, which includes: electromagnetic sensor, controller, auto-pressurizing nitrogen storage tank, main solenoid valve, secondary solenoid valve, pressure charging valve, exhaust reducing valve and exhaust valve.The level value of the liquid nitrogen in liquid nitrogen container can be measured in real time and be shown using the present invention, and realize the function of carrying out automatic liquid supply to liquid nitrogen container.
Description
Technical field
This application involves Technology of Level Detection field more particularly to a kind of liquid level detection systems based on Electromagnetic Wave Method.
Background technique
In high-temperature superconducting magnetic levitation technology, usually superconduction block material is immersed in liquid nitrogen, is lowered into its temperature
Superconducting state, superconduction block material and external magnetic field into superconducting state can reach stable suspersion.In high temperature superconductor magnetic levitation vehicle
Whole service during, it is necessary to assure superconduction block material is the liquid nitrogen being immersed in liquid nitrogen container (for example, vehicle-mounted Dewar) always
The inside is just avoided that and quenches phenomenon.High-temperature superconductor, which quenches to will lead to train and lose suspending power and track, occurs friction very
To derailing.
However, can not be detected by an unaided eye in liquid nitrogen container due to the metal material and vacuum insulation characteristic of liquid nitrogen container
Remaining liquid nitrogen liquid level you must use suitable liquid nitrogen level detection system and carry out to the liquid nitrogen level in liquid nitrogen container
Detection, to judge whether to need to fill liquid nitrogen in time.
Currently, liquid nitrogen level detection method in the prior art is usually all to measure liquid nitrogen appearance using the method for contact
Liquid level in device, mainly by installing the detection devices such as liquid level sensor in liquid nitrogen container, by liquid nitrogen container
Sensor measurement obtained temperature data and detect the liquid level in liquid nitrogen container in conjunction with sensor mounting location.It is surveying
It, can be by the way that highest and lowest liquid level, fluid infusion and drain when needed, to control be arranged after having measured liquid nitrogen level
Liquid nitrogen level height in liquid nitrogen container processed is in default range.
But since detection method in the prior art is using contact type measurement, it is therefore desirable to by cable and sensing
Device is introduced into liquid nitrogen container, this will increase heat transfer to increase the loss of liquid nitrogen.On the other hand, liquid nitrogen is that temperature is extremely low
Liquid and readily volatilized therefore high for the material requirements of the hardware such as the sensor of contact type measurement, lead, and liquid nitrogen
The huge temperature difference inside and outside container will lead to sensor surface and frost occurs, to would necessarily affect entire detection system
Precision and long-time stability are not suitable for measuring for a long time so easily causing measurement error.In addition, in the prior art to liquid nitrogen liquid
The detection in face is a kind of automanual detection scheme, needs the participation of people, cannot achieve the real-time detection to liquid nitrogen level, low
Liquid level warning, liquid nitrogen auto-filling, full of the functions such as automatically cutting off and remind.
Summary of the invention
In view of this, the present invention provides a kind of liquid level detection systems based on Electromagnetic Wave Method, so as to hold to liquid nitrogen
The level value of liquid nitrogen in device is measured in real time and shows, and realizes the function that automatic liquid supply is carried out to liquid nitrogen container.
Technical solution of the present invention is specifically achieved in that
A kind of liquid level detection system based on Electromagnetic Wave Method, the system include: electromagnetic sensor, controller, are pressurized certainly
Formula nitrogen storage tank, main solenoid valve, secondary solenoid valve, pressure charging valve, exhaust reducing valve and exhaust valve；
The electromagnetic sensor is arranged in the top of the gas outlet of the liquid nitrogen container for holding liquid nitrogen, and with the control
The analog input channel of device processed connects；
The controller respectively with electromagnetic sensor, main solenoid valve, secondary solenoid valve, exhaust reducing valve, pressure charging valve, exhaust
Valve is connected with host computer；
One end of first liquid-transport pipe-line is protruded into the liquid nitrogen in auto-pressurizing nitrogen storage tank, described in other end stretching
Auto-pressurizing nitrogen storage tank is connect with the main solenoid valve；
One end of the main solenoid valve is connect with first liquid-transport pipe-line, and one end of the other end and the liquid filling pipeline connects
It connects；
The other end of the liquid filling pipeline is connect with one end of the secondary solenoid valve；
The other end of the secondary solenoid valve is connect with one end of second liquid-transport pipe-line；
The bottom of second liquid-transport pipe-line is protruded into the liquid nitrogen container, and the liquid nitrogen container and described time are stretched out in top
Solenoid valve connection；
The exhaust valve is arranged on the liquid filling pipeline；
The bottom of the gas relief line is protruded into the auto-pressurizing nitrogen storage tank, and the auto-pressurizing liquid is stretched out at top
Nitrogen holding vessel is connect with the exhaust reducing valve；
The bottom of the pressure pipeline is protruded into the auto-pressurizing nitrogen storage tank, and the auto-pressurizing liquid is stretched out at top
Nitrogen holding vessel is connect with the pressure charging valve.
Preferably, the electromagnetic sensor includes: optical pulse generator, delayer, photelectric receiver, timing pulse vibration
Swing device, electronic gate, counting and display device；
The optical pulse generator for emitting the first light pulse to measured target, and passes through optical fiber to delayer simultaneously
Emit the second light pulse；
The delayer exports after the second light pulse delay for that will receive to photelectric receiver；
The photelectric receiver, after receiving the back wave of measured target reflection and the delay of delayer output
The second light pulse, and the second light pulse after the back wave received and delay is converted into back wave electric pulse and ginseng respectively
It exports after examining wave electric pulse to the electronic gate；
The timing pulse oscillator, for generating the timing pulse of fixed frequency, and timing pulse generated is defeated
Out to the electronic gate；
The electronic gate, for opening the electronic gate when receiving reference wave electric pulse, and electronic gate is opened
Starting point of the moment as this timing, and the timing pulse received and reference wave electric pulse are exported to the counting and display
Device；When receiving back wave electric pulse, back wave electric pulse is exported to the counting and display device, and described in closing
Electronic gate, as the terminal of this timing at the time of electronic gate is closed, no longer to counting and display device output signal；
The counting and display device, for recording the quantity of the timing pulse received, according to the markers arteries and veins received
The quantity of punching is calculated distance value and shows, and by the launch time of the first light pulse, the receiving time of back wave, the second light
The receiving time of the launch time of pulse and the second light pulse is exported to the analog input channel of the controller.
Preferably, in the system further include: one or more signal lamps；
The controller is connect with each signal lamp respectively, and the on-off of each signal lamp is controlled by control signal.
Preferably, the controller is programmable logic controller (PLC).
Preferably, the host computer is PC, server or control centre.
As above as it can be seen that in the liquid level detection system based on Electromagnetic Wave Method in the present invention, due to being passed using electromagnetic wave
Sensor monitors the liquid level in liquid nitrogen container, it is not necessary that cable and sensor to be introduced into liquid nitrogen container, therefore is a kind of non-connect
The measurement method of touch, and it is not contact type measurement mode, so as to be effectively prevented from leakage caused by contact type measurement
Heat problem avoids the loss of liquid nitrogen caused by heat transfer；Hold moreover, because electromagnetic sensor does not need contact liquid nitrogen
Device, therefore the phenomenon that also avoid sensor surface frosting caused by the huge temperature difference inside and outside liquid nitrogen container, monitoring accuracy is more
It is high, more acurrate, improve the precision and long-time stability of entire detection system.In addition, the liquid level detection system in the present invention is also
Liquid nitrogen can be supplemented from trend liquid nitrogen container according to the liquid level in the liquid nitrogen container that real-time detection arrives, to realize full-automatic
Liquid nitrogen auto-filling, without the participation of staff, but also can reduction filling time and liquid nitrogen loss.Separately
Outside, the liquid level detection system in the present invention can also further realize low liquid level warning, be automatically stopped after liquid nitrogen is full of it is filling simultaneously
The functions such as prompting.
Detailed description of the invention
Fig. 1 is the structural schematic diagram of the liquid level detection system based on Electromagnetic Wave Method in the embodiment of the present invention.
Fig. 2 is the structural schematic diagram of the electromagnetic sensor in the embodiment of the present invention.
Fig. 3 is the schematic illustration of the error concealment in the embodiment of the present invention.
Specific embodiment
For technical solution of the present invention and advantage is more clearly understood, below in conjunction with drawings and the specific embodiments, to this
Invention is described in further detail.
Fig. 1 is the structural schematic diagram of the liquid level detection system based on Electromagnetic Wave Method in the embodiment of the present invention.
As shown in Figure 1, the liquid level detection system based on Electromagnetic Wave Method in the embodiment of the present invention includes: electromagnetic sensor
4, controller 13, auto-pressurizing nitrogen storage tank 11, main solenoid valve 8, secondary solenoid valve 5, pressure charging valve 10, exhaust reducing valve 9 and row
Air valve 6；
The electromagnetic sensor 4 is arranged in the top of the gas outlet 3 of the liquid nitrogen container 2 for holding liquid nitrogen 1, and with institute
State the analog input channel connection of controller 13；
The controller 13 respectively with electromagnetic sensor 4, main solenoid valve 8, secondary solenoid valve 5, exhaust reducing valve 9, pressurization
Valve 10, exhaust valve 6 and host computer 12 connect；
One end of first liquid-transport pipe-line 21 is protruded into the liquid nitrogen in auto-pressurizing nitrogen storage tank 11, and the other end stretches out
The auto-pressurizing nitrogen storage tank 11 is connect with the main solenoid valve 8；
One end of the main solenoid valve 8 is connect with first liquid-transport pipe-line 21, and the one of the other end and the liquid filling pipeline 7
End connection；
The other end of the liquid filling pipeline 7 is connect with one end of the secondary solenoid valve 5；
The other end of the secondary solenoid valve 5 is connect with one end of second liquid-transport pipe-line 22；
The bottom of second liquid-transport pipe-line 22 is protruded into the liquid nitrogen container 2, and the liquid nitrogen container 2 and institute are stretched out in top
Time solenoid valve 5 is stated to connect；
The exhaust valve 6 is arranged on the liquid filling pipeline 7；
The bottom of the gas relief line 23 is protruded into the auto-pressurizing nitrogen storage tank 11, and top is stretched out described from pressurization
Formula nitrogen storage tank 11 is connect with the exhaust reducing valve 9；
The bottom of the pressure pipeline 24 is protruded into the auto-pressurizing nitrogen storage tank 11, and top is stretched out described from pressurization
Formula nitrogen storage tank 11 is connect with the pressure charging valve 10.
In the above-mentioned liquid level detection system based on Electromagnetic Wave Method, electromagnetic sensor can emit a branch of electromagnetic wave
(can be described as detection electromagnetic wave), which enters the inside of liquid nitrogen container by the gas outlet of liquid nitrogen container, in liquid nitrogen
It is reflected at liquid level in container.When electromagnetic sensor detects the back wave being reflected back, electromagnetic wave sensing
The time that device emits and receive the detection electromagnetic wave can be input in controller by the analog input channel of controller.Separately
Outside, while emitting above-mentioned detection electromagnetic wave, the electromagnetic wave that can also send a branch of delay (can be described as joining the electromagnetic sensor
Examine electromagnetic wave)；The electromagnetic sensor emits and receive the time for referring to electromagnetic wave can also be defeated by the analog quantity of controller
Enter channel to be input in controller.
Since reference electromagnetic wave has been delayed by a period of time, when controller can be according to the delay of reference electromagnetic wave
Between, with reference to the time difference between the receiving time of electromagnetic wave and the receiving time of back wave, determine current institute's ranging from (i.e. electromagnetism
The distance at liquid level in wave sensor to liquid nitrogen container)；Then, further according to the electromagnetic sensor and liquid nitrogen container (for example,
Vehicle-mounted Dewar) mounting height and liquid nitrogen container height, the current level of the liquid nitrogen in liquid nitrogen container can be calculated
Value.The current level value of liquid nitrogen in liquid nitrogen container can be sent to host computer (for example, by PC/PPI cable by the controller
It is sent to host computer) so that user can be by host computer come the level value of the liquid nitrogen in real-time monitoring liquid nitrogen container.
In addition, due to the controller also respectively with main solenoid valve, secondary solenoid valve, exhaust reducing valve, pressure charging valve, exhaust valve and
Host computer connection, therefore the controller can also be by control signal (for example, the digital output channel by controller exports
High level or low level) control the on-off of main solenoid valve, secondary solenoid valve, exhaust reducing valve, pressure charging valve and exhaust valve, so as to
Further to realize the function to liquid nitrogen container automatic liquid supply.
For example, can be held according to liquid nitrogen after the current level value of the liquid nitrogen in liquid nitrogen container is calculated in controller
The current level value of liquid nitrogen in device determines the need for supplementing liquid nitrogen into liquid nitrogen container.For example, when in liquid nitrogen container
When the current level value of liquid nitrogen is less than preset minimum level value, it can start to supplement liquid nitrogen into liquid nitrogen container.
When needing to supplement liquid nitrogen into liquid nitrogen container, controller can be made on liquid filling pipeline 7 by controlling signal
(when not needing to supplement liquid nitrogen into liquid nitrogen container, the exhaust valve 6 is in the open state, to guarantee to fill for the normally opened closing of exhaust valve 6
Air pressure in liquid pipe road 7 is the pressure of a safety, to prevent in liquid filling pipeline 7 air pressure excessive and lead to 7 quilt of liquid filling pipeline
It destroys；And when needing to supplement liquid nitrogen into liquid nitrogen container or liquid filling pipeline 7 is pre-chilled, in order to guarantee in liquid filling pipeline 7
There are enough air pressures, liquid nitrogen to be pressed into liquid nitrogen container or liquid filling pipeline 7 using pressure difference, it is therefore desirable to close the exhaust valve
6), so that the normally opened exhaust reducing valve 9 in auto-pressurizing nitrogen storage tank 11 closes and (do not needing the replenisher into liquid nitrogen container
When nitrogen, the exhaust reducing valve 9 is in the open state), and the normally closed pressure charging valve 10 in auto-pressurizing nitrogen storage tank 11 is beaten
Open (when not needing to supplement liquid nitrogen into liquid nitrogen container, which is in close state).At this point, external heat will pass through increasing
Pressure valve and pressure pipeline enter auto-pressurizing nitrogen storage tank, so that the liquid nitrogen in auto-pressurizing nitrogen storage tank accelerates evaporation,
So that the air pressure in auto-pressurizing nitrogen storage tank increases, to achieve the purpose that pressurization.
When the air pressure in auto-pressurizing nitrogen storage tank increases, liquid nitrogen in auto-pressurizing nitrogen storage tank will be along the
One liquid-transport pipe-line rises.In addition, before supplementing liquid nitrogen into liquid nitrogen container needing that first liquid filling pipeline is pre-chilled.Therefore,
Controller can the normally closed main solenoid valve on the first liquid-transport pipe-line open (not need to liquid nitrogen by controlling signal at this time
In container when supplement liquid nitrogen, which is in close state), and the secondary solenoid valve on the second liquid-transport pipe-line is closed,
Therefore the liquid nitrogen in auto-pressurizing nitrogen storage tank will enter liquid filling pipeline by main solenoid valve along the first liquid-transport pipe-line
In.Since main solenoid valve is opened at this time, and secondary solenoid valve is in closed state, therefore enters the liquid nitrogen in liquid filling pipeline
It will promptly vaporize, so that the temperature of liquid filling pipeline is promptly reduced.At this point, controller can be opened by control signal
Liquid filling pipeline will be discharged from the exhaust valve 6 in exhaust valve 6 on liquid filling pipeline 7, the liquid nitrogen after vaporization.
After preset duration is pre-chilled, controller can by control signal-off liquid filling pipeline 7 on exhaust valve 6, and
The secondary solenoid valve on the second liquid-transport pipe-line is opened, so that the liquid nitrogen of liquid filling pipeline 7 flows into liquid nitrogen container 2, is started to liquid
Liquid nitrogen is supplemented in nitrogen cascade 2.
When no longer needing to supplement liquid nitrogen into liquid nitrogen container 2 (for example, the current level value of the liquid nitrogen in liquid nitrogen container is big
When preset highest fluid value), controller can pass through the secondary electromagnetism on control the second liquid-transport pipe-line of signal-off
Valve closes the main solenoid valve on the first liquid-transport pipe-line, and opens the exhaust valve 6 on liquid filling pipeline 7, stops into liquid nitrogen container 2
Liquid nitrogen is supplemented, and each solenoid valve is made to be restored to the state before fluid infusion, is automatically stopped filling after liquid nitrogen is full of so as to realize
The function of dress.At this point, controller can also send prompting message by position machine further up, to inform that user has been completed liquid nitrogen
Auto-filling.
In addition, in the inventive solutions, when not needing to supplement liquid nitrogen into liquid nitrogen container, auto-pressurizing liquid nitrogen
Exhaust reducing valve 9 on holding vessel 11 be it is in the open state, so as to discharge the air pressure in auto-pressurizing nitrogen storage tank,
To maintain the pressure in auto-pressurizing nitrogen storage tank to be in steady state.And when needing to supplement liquid nitrogen into liquid nitrogen container,
Controller can make the exhaust reducing valve 9 close by controlling signal, and open pressure charging valve 10, so that auto-pressurizing liquid nitrogen stores up
The liquid nitrogen deposited in tank accelerates evaporation, so that the air pressure in auto-pressurizing nitrogen storage tank increases, so that auto-pressurizing
Liquid nitrogen in nitrogen storage tank is by air pressure indentation liquid filling pipeline 7.
In addition, in the inventive solutions, when the current level value of the liquid nitrogen in liquid nitrogen container is less than preset report
When alert fluid value, controller can also send warning message to host computer, with remind user current level value already below report
Alert fluid value, needs to supplement liquid nitrogen into liquid nitrogen container.
It, not only can be to liquid nitrogen according to foregoing description it is found that by the above-mentioned liquid level detection system based on Electromagnetic Wave Method
The level value of liquid nitrogen in container is measured in real time, after can also realizing that low liquid level warning, liquid nitrogen auto-filling, liquid nitrogen are full of
It is automatically stopped the filling and functions such as prompting.
In addition, in the inventive solutions, above-mentioned electromagnetic wave sensing can be realized by a variety of implementations
Device will be introduced technical solution of the present invention by taking one such specific implementation as an example below.
For example, preferably, as shown in Fig. 2, in one particular embodiment of the present invention, the electromagnetic sensor packet
Include: optical pulse generator 31, photelectric receiver 33, timing pulse oscillator 34, electronic gate 35, is counted and is shown delayer 32
Device 36；
The optical pulse generator 31, for emitting the first light pulse (i.e. detection electromagnetic wave) to measured target 30, and it is same
When the second light pulse (refer to electromagnetic wave) is emitted to delayer 32 by optical fiber；
The delayer 32 exports after the second light pulse delay for that will receive to photelectric receiver 33；
The photelectric receiver 33, what back wave and the delayer 32 for receiving the reflection of measured target 30 exported
The second light pulse after delay, and the second light pulse after the back wave received and delay is converted into back wave electricity arteries and veins respectively
It exports after punching and reference wave electric pulse to the electronic gate 35；
The timing pulse oscillator 34, for generating the timing pulse of fixed frequency, and by timing pulse generated
It exports to the electronic gate 35；
The electronic gate 35, is opened for opening the electronic gate when receiving reference wave electric pulse, and by electronic gate
At the time of starting point as this timing, and the timing pulse received and reference wave electric pulse are exported to the counting and aobvious
Showing device 36；When receiving back wave electric pulse, back wave electric pulse is exported to the counting and display device 36, and is closed
The electronic gate is closed, as the terminal of this timing at the time of electronic gate is closed, is no longer exported to counting and display device 36
Signal；
The counting and display device 36, for recording the quantity of the timing pulse received, according to the markers received
The quantity of pulse is calculated distance value and shows, and by the launch time of the first light pulse, the receiving time of back wave, second
The receiving time of the launch time of light pulse and the second light pulse is exported to the analog input channel of the controller 13.
In above-mentioned electromagnetic sensor, timing pulse oscillator can provide the timing pulse of a fixed frequency,
Benchmark as a time.After electronic gate is opened, by starting point at the time of opening using the electronic gate as this timing, directly
When being closed to the electronic gate, as the terminal of this timing at the time of which is closed.Due to the transmission frequency of timing pulse
Rate be it is fixed, so the time interval between two neighboring timing pulse is also fixed, therefore electronic gate can be passed through
Primary opening-closing course in received timing pulse number, the primary opening-for calculating the electronic gate was closed
The duration of journey (process of electronic gate is closed from reference wave electric pulse opening electronic gate to back wave electric pulse), i.e., it is above-mentioned
A timing duration.So above-mentioned electronic gate is equivalent to the switch of counting and display device.Before carrying out ranging, electricity
Cervical orifice of uterus is in close state.At this point, timing pulse not can enter counting and display device；And when carrying out ranging, work as electronic gate
When receiving with reference to electromagnetic wave (i.e. the second light pulse) corresponding reference wave electric pulse, electronic gate is opened, and timing starts, markers
Pulse singly passes through electronic gate and exports to counting and display device, the counting and display device start recording timing pulse
Number；And when electronic gate receives and back wave (i.e. reflection after being reflected after on the first light pulse emission to measured target
Wave) corresponding back wave electric pulse when, electronic gate is closed, and the counting and display device stop counting.At this point, counting and showing dress
Distance value can be calculated, and can also show the distance value according to the quantity of the timing pulse recorded by setting.
For example, it is assumed that the distance between electromagnetic sensor and measured target are D, then:
Wherein, C is electromagnetic wave or the speed that light pulse is propagated in an atmosphere, t2DIt is passed for electromagnetic wave or light pulse in electromagnetic wave
The roundtrip propagation primary required time between sensor and measured target.
Due to:
t2D=nt (2)
Wherein, n is the number of timing pulse, time interval of the t between two neighboring timing pulse.
Therefore it can obtain:
Assuming that the distance that electromagnetic wave or light pulse are propagated in time t/2 is a unit distance d, i.e.,
It can then obtain:
According to above-mentioned formula (5) it is found that a selected unit distance d value (for example, 1cm, 5cm or 10cm etc., specifically
Value can be demarcated by timing pulse oscillator) after, the value of d is a definite value, as long as therefore having known and being recorded
Timing pulse quantity n, the distance between electromagnetic sensor and measured target D can directly be calculated.
In above-mentioned electromagnetic sensor, optical pulse generator 31 emits a branch of detection electromagnetic wave to measured target 30,
Emitted simultaneously by optical fiber to delayer 32 a branch of with reference to electromagnetic wave；Detect the back wave after electromagnetic wave is reflected by measured target 30
It can be received by photelectric receiver 33, and the photelectric receiver 33 can also receive the ginseng after delay from delayer 32
Examine electromagnetic wave.It, can be according to the delay time of reference electromagnetic wave, reference since reference electromagnetic wave has been delayed by a period of time
Time difference between the receiving time of electromagnetic wave and the receiving time of back wave determines electromagnetic sensor to measured target 30
The distance between (at liquid level i.e. in liquid nitrogen container).
Since electromagnetic wave propagation will receive the influence of air refraction, temperature, humidity, electromagnetic wave meeting in communication process
The deviations such as refraction occur, therefore are provided with the delayer transmitted based on optical fiber in above-mentioned electromagnetic sensor, and utilizing should
Delayer is compensated due to the error that refraction occurs for Electromagnetic Wave Propagation and generates, thus even if when above-mentioned electromagnetic sensor and
When the distance between measured target very little, the electromagnetic sensor also can be used and carry out high-precision ranging.
In addition, preferably, in one particular embodiment of the present invention, in addition to being missed in measurement process using delayer
Except accuracy of the difference compensation to improve measurement, can also after electromagnetic sensor is set, to the electromagnetic sensor into
The certain error concealment of row.
For example, error concealment can be carried out to the electromagnetic sensor by step as described below:
Step 1, after electromagnetic sensor installation being fixed, the liquid level of the liquid nitrogen in liquid nitrogen container is adjusted to highest liquid level
Value.
Step 2, the current level value of the liquid nitrogen in liquid nitrogen container is obtained by electromagnetic sensor measurement, and this is current
Level value is as the first level value；Using the difference of first level value and highest fluid value as first error value.
Step 3, the liquid level of the liquid nitrogen in liquid nitrogen container is adjusted to minimum level value.
Step 4, the current level value of the liquid nitrogen in liquid nitrogen container is obtained by electromagnetic sensor measurement, and this is current
Level value is as the second level value；Using the difference of second level value and minimum level value as the second error amount.
Step 5, using the average value of first error value and the second error amount as error compensation value.
Therefore, after carrying out above-mentioned error concealment, an available error compensation value.When in subsequent process
In, when carrying out ranging using electromagnetic sensor, error concealment can will be carried out according to above-mentioned error compensation value.For example, working as
During subsequent, the current level value that electromagnetic sensor measurement obtains the liquid nitrogen in liquid nitrogen container is h, then can should
(h+ error compensation value) is as final measured value.
In the inventive solutions, above-mentioned error concealment only need to be carried out when electromagnetic sensor is installed for the first time,
Hereafter it then no longer needs to carry out above-mentioned error concealment.
For another example error concealment can also be carried out to the electromagnetic sensor by step as described below:
The liquid level of liquid nitrogen in liquid nitrogen container is adjusted to highest liquid level after fixing electromagnetic sensor installation by step I
Value, will be denoted as A by true highest level value at this time.
Step II, the current level value of the liquid nitrogen in liquid nitrogen container is obtained by electromagnetic sensor measurement, and will be deserved
Preceding level value is as the first level value H.
Step III, using the difference of A and H as error compensation value.
It, can be in the follow-up process using electromagnetic sensor to liquid nitrogen according to the difference between above-mentioned two values A and H
When any liquid level of liquid nitrogen in container carries out ranging, corresponding error compensation is carried out.
For example, ought be surveyed in the follow-up process using any liquid level of the electromagnetic sensor to the liquid nitrogen in liquid nitrogen container
Away from when, it is assumed that the level value measured be h, then by formula below can to currently measure level value h progress error
Compensation obtains more accurate current true level value a:
A=h+ (A-H) (6)
Its principle are as follows: when due to measurement the first level value H and current level value h, all there is identical error, therefore the mistake
Difference can should be eliminated by (H-h).For example, it is assumed that the level value obtained measured by electromagnetic sensor is actually than true
Level value want larger, then when measuring H and h, error amount should be it is identical, i.e., measured value is all than true liquid
Place value is big.So above-mentioned error amount can be eliminated by (H-h).Wherein, as shown in figure 3, by (H-h) actually institute
That indicate is the distance between the highest fluid value H of liquid nitrogen in current level value h and liquid nitrogen container, therefore by true highest
Level value A subtracts (H-h), current true level value a can be obtained, i.e.,
A=A- (H-h)=h+ (A-H) (7)
Therefore, by the difference between above-mentioned A and H, corresponding error compensation can be carried out to electromagnetic sensor.
In addition, preferably, in one particular embodiment of the present invention, obtaining corresponding liquid nitrogen measuring preset number
After the level value of liquid nitrogen in container, each measured value that measurement obtains can be compared with actual level value, then
The delay time of delayer is modified according to comparison result, so as to further reduce error, improves measurement accuracy, it is real
The now high-acruracy survey of short distance.
In addition, preferably, in one particular embodiment of the present invention, the liquid level detection system based on Electromagnetic Wave Method
In can further include: one or more signal lamps 14；
The controller 13 connect respectively with each signal lamp 14 (for example, by the digital output channel of controller with
The connection of each signal lamp), and control by control signal the on-off of each signal lamp 14, so as to realize liquid level instruction,
Low liquid level warning such as is automatically reminded at the functions after being full of.
In addition, preferably, in one particular embodiment of the present invention, the controller can be Programmable logical controller
Device (PLC).
In addition, preferably, in one particular embodiment of the present invention, the host computer can be PC, service
The various equipment such as device or control centre.By the way that configuration software is arranged in the host computer, the host computer can be according to reception
The data arrived, real-time display liquid nitrogen level can also further generate Historical Alerts and related data report etc..
In conclusion in the inventive solutions, due to being monitored in liquid nitrogen container using electromagnetic sensor
Liquid level, it is not necessary that cable and sensor to be introduced into liquid nitrogen container, therefore be a kind of contactless measurement method, and not
Contact type measurement mode, so as to be effectively prevented from leakage heat problem caused by contact type measurement, avoid heat transfer and
The loss of caused liquid nitrogen；Moreover, because electromagnetic sensor does not need contact liquid nitrogen container, therefore also avoid liquid nitrogen container
Caused by the inside and outside huge temperature difference the phenomenon that sensor surface frosting, monitoring accuracy is higher, more acurrate, improves entire detection
The precision and long-time stability of system.In addition, the liquid nitrogen that the liquid level detection system in the present invention can also be arrived according to real-time detection
Liquid level in container supplements liquid nitrogen from trend liquid nitrogen container, so that full automatic liquid nitrogen auto-filling is realized, without work
Make the participation of personnel, but also can reduction filling time and liquid nitrogen loss.In addition, the liquid level detection system in the present invention is also
Low liquid level warning can be further realized, is automatically stopped after liquid nitrogen is full of filling and the functions such as reminds.In addition, in skill of the invention
In art scheme, since further temperature-compensating can also be carried out to electromagnetic sensor, the standard of level gauging can be improved
Exactness and precision.So the above-mentioned liquid level inspection based on Electromagnetic Wave Method compared with the relevant technologies in the prior art, in the present invention
The degree of automation of examining system is very high, and the ability for adapting to electromagnetic environment is strong, and man-machine interface is friendly, therefore is particularly suitable for magnetic suspension column
Vehicle is engineered this specific application scenario；Moreover, using controller (for example, PLC) plus host computer (for example, a in the present invention
People's computer) detection mode, the complex electromagnetic environment being well suited on magnetic suspension train.
The foregoing is merely illustrative of the preferred embodiments of the present invention, is not intended to limit the invention, all in essence of the invention
Within mind and principle, any modification, equivalent substitution, improvement and etc. done be should be included within the scope of the present invention.
Claims (5)
1. a kind of liquid level detection system based on Electromagnetic Wave Method, which is characterized in that the system includes: electromagnetic sensor, control
Device, auto-pressurizing nitrogen storage tank, main solenoid valve, secondary solenoid valve, pressure charging valve, exhaust reducing valve and exhaust valve；
The electromagnetic sensor is arranged in the top of the gas outlet of the liquid nitrogen container for holding liquid nitrogen, and with the controller
Analog input channel connection；
The controller respectively with electromagnetic sensor, main solenoid valve, secondary solenoid valve, exhaust reducing valve, pressure charging valve, exhaust valve and
Host computer connection；
One end of first liquid-transport pipe-line is protruded into the liquid nitrogen in auto-pressurizing nitrogen storage tank, and the other end stretches out described from increasing
Pressure type nitrogen storage tank is connect with the main solenoid valve；
One end of the main solenoid valve is connect with first liquid-transport pipe-line, and the other end is connect with one end of the liquid filling pipeline；
The other end of the liquid filling pipeline is connect with one end of the secondary solenoid valve；
The other end of the secondary solenoid valve is connect with one end of second liquid-transport pipe-line；
The bottom of second liquid-transport pipe-line is protruded into the liquid nitrogen container, and the liquid nitrogen container and the secondary electromagnetism are stretched out in top
Valve connection；
The exhaust valve is arranged on the liquid filling pipeline；
The bottom of the gas relief line is protruded into the auto-pressurizing nitrogen storage tank, and the auto-pressurizing liquid nitrogen storage is stretched out at top
Tank is deposited to connect with the exhaust reducing valve；
The bottom of the pressure pipeline is protruded into the auto-pressurizing nitrogen storage tank, and the auto-pressurizing liquid nitrogen storage is stretched out at top
Tank is deposited to connect with the pressure charging valve.
2. system according to claim 1, which is characterized in that the electromagnetic sensor includes: optical pulse generator, prolongs
When device, photelectric receiver, timing pulse oscillator, electronic gate, counting and display device；
The optical pulse generator is emitted by optical fiber to delayer for emitting the first light pulse to measured target, and simultaneously
Second light pulse；
The delayer exports after the second light pulse delay for that will receive to photelectric receiver；
The photelectric receiver, for receiving the after the back wave of measured target reflection and the delay of delayer output
Two light pulses, and the second light pulse after the back wave received and delay is converted into back wave electric pulse and reference wave respectively
It exports after electric pulse to the electronic gate；
The timing pulse oscillator, for generating the timing pulse of fixed frequency, and by timing pulse generated export to
The electronic gate；
The electronic gate, for opening the electronic gate when receiving reference wave electric pulse, and at the time of electronic gate is opened
As the starting point of this timing, and the timing pulse received and reference wave electric pulse are exported to the counting and display and filled
It sets；When receiving back wave electric pulse, back wave electric pulse is exported to the counting and display device, and closes the electricity
Cervical orifice of uterus, as the terminal of this timing at the time of electronic gate is closed, no longer to counting and display device output signal；
The counting and display device, for recording the quantity of the timing pulse received, according to the timing pulse received
Quantity is calculated distance value and shows, and by the launch time of the first light pulse, the receiving time of back wave, the second light pulse
Launch time and the receiving time of the second light pulse export to the analog input channel of the controller.
3. system according to claim 1, which is characterized in that in the system further include: one or more signal lamps；
The controller is connect with each signal lamp respectively, and the on-off of each signal lamp is controlled by control signal.
4. system according to claim 1, it is characterised in that:
The controller is programmable logic controller (PLC).
5. system according to claim 1, it is characterised in that:
The host computer is PC, server or control centre.
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