CN204228233U - High-precision intelligent multiple solutions liquid level sensor detection system - Google Patents

Abstract

The utility model discloses a kind of high-precision intelligent multiple solutions liquid level sensor detection system.Comprise power module, MCU, the sine wave generation module be connected with MCU, with sine wave, the multiway analog switch module that module is connected, the segmented capacitive interface be connected with multiway analog switch module occur with MCU, between described MCU and multiway analog switch module, be connected to leakage resistance measurement module and phase difference detection module; It is characterized in that: described segmented capacitive interface is connected to bipolar electrode capacitive transducer, described bipolar electrode capacitive transducer is wrapped in the symmetry electrode (2) on insulcrete (1) by insulcrete (1), symmetry, the end of symmetry electrode (2) is connected with segmented capacitive interface by electrode (3).The utility model can not only carry out Measurement accuracy to single interface level, and can also realize the Measurement accuracy to two or more multiple solutions liquid levels, and measuring accuracy is less than 5mm.

Description

High-precision intelligent multiple solutions liquid level sensor detection system

Technical field

The utility model belongs to the technical field of measurement, specifically refers to a kind of high-precision intelligent multiple solutions liquid level sensor detection system.

Background technology

In numerous industries such as petrochemical complex, traffic channel, hydraulic and electric engineering, field irrigation, environmental monitoring and food processings, liquid level is an important technical parameter.Level sensing divides level sensing and the multiple solutions level sensing at single interface, the accurate detection of multiple solutions liquid level is the study hotspot of sensing detection technical elements all the time, also be a gordian technique of control field, whether level sensing accurately will directly affect the operating condition of whole system simultaneously.

At present, the middle and later periods of oil extraction in oil field at home, the water content in crude oil exploited out is comparatively large, oil-water mixture must be sent in petroleum crude separator and carry out oil and water separation.After oil-water mixture leaves standstill certain hour in the separator, under gravity, droplet in mixed liquor pools large water droplet and is deposited to separator bottom, oil reservoir is then bubbled through the water column, form interphase between an oil layer and a water layer, by being separated the object of drawing and just achieving oil and water separation to water layer and oil reservoir.Real-time Accurate Determining interphase position, to pump in time, draw water and oil-feed water mixed liquid, is the key point in this equipment use.

At sea in oil spilling processing procedure, floating oil spilling across the sea sucks in recovery bin by oil collector, but has inevitably sucked part seawater while oil suction, therefore must carry out the mask work of seawater and oil spilling in recovery bin.In recovery bin, be air, oil and seawater from top to bottom successively according to proportion.Recovery bin arranges two outlets, and the effect of oil pumping mouth is that pure oil spilling is sucked oil storage cabin, and the effect of pump mouth is that seawater is discharged.Because storehouse external and internal pressure is uneven, outside oil-water mixture is constantly inhaled in recovery bin.When pump, when draw water, will judge according to the testing result of liquid level sensor.When the height of oil water surface (interface 1) is higher than the height of pump mouth, carry out work of drawing water; When interface 1 height lower than oil pumping mouth height, and the height at gas-oil interface (interface 2) higher than oil pumping mouth height, then carry out pumping operation.In order to realize the Inspect and control to detachment process, liquid level sensor must detect oil water surface and gas-oil interface in recovery bin exactly.Due to the physical characteristics of oil-water mixture complexity, the detection of water-oil interface is very special.

Technology and the product of domestic and international employing in level sensing are at present a lot, and new measuring technique is also continuing to bring out.By the measuring technique that sensor adopts, single interface level sensor mainly contains following several: float type liquid level sensor, servo liquid sensor, differential pressure type level sensor, contactless liquid level sensor, single hop capacitance level transducer, optical fiber type liquid level sensor etc.Above liquid level sensor, General Requirements measures liquid uniform concentration and single interface (air and liquid interface).Ultrasonic liquid level sensor can measure multilayer liquid interface, but requires that strength of fluid is even, and degree of purity is good, and inconvenience uses in small distance is measured.Except ultrasonic liquid level sensor, the liquid level sensor measuring multiple solutions at present has: magnetostrictive liquid level sensor, sectional capacitor type liquid level sensor.There is Railway Project in this sensor: sensor contacts with fluid to be measured, is easily corroded, and liquid density variation can bring measuring error, and float moves up and down along the pipe of protecting and leading outside waveguide, is easily stuck; In structure, its metering circuit of existing sectional capacitor type liquid level sensor adopts complicated analogue technique mostly, as transformer bridges formula, operational amplifier formula and pulse width type etc., reliability is not high, antijamming capability is weak, and intelligence degree is not high, inconvenient with master controller communication.

Above-mentioned discussion content object be to reader introduce may to below by the various aspects of technology relevant for the various aspects of the present utility model be described and/or advocate, believe that this discussion content contributes to for reader with background's information, to be conducive to understanding various aspects of the present utility model better, therefore, should be appreciated that it is discuss to read these with this angle, instead of admit prior art.

Utility model content

The purpose of this utility model is avoid deficiency of the prior art and provide a kind of high-precision intelligent multiple solutions liquid level sensor detection system, its level detection precision is high, Measurement accuracy can not only be carried out to single interface level, and the Measurement accuracy to two or more multiple solutions liquid levels can also be realized.

The purpose of this utility model is achieved through the following technical solutions:

A kind of high-precision intelligent multiple solutions liquid level sensor detection system is provided, comprise power module, MCU, the sine wave generation module be connected with MCU, with sine wave, the multiway analog switch module that module is connected, the segmented capacitive interface be connected with multiway analog switch module occur with MCU, between described MCU and multiway analog switch module, be connected to leakage resistance measurement module and phase difference detection module; Described segmented capacitive interface is connected to bipolar electrode capacitive transducer, and described bipolar electrode capacitive transducer is wrapped in the symmetry electrode 2 on insulcrete 1 by insulcrete 1, symmetry, and the end of symmetry electrode 2 is connected with segmented capacitive interface by electrode 3.

Wherein, the temperature sensing 18B20 module, serial communication interface module, the human-machine interface module that are connected with MCU is also comprised.

Wherein, described multiway analog switch module is integrated multiway analog switch module chip CD4051.

Wherein, described MCU is ATmega16 single-chip microcomputer, the A/D converter on integrated 10,8 tunnel and an analog comparator.

Wherein, there is module and adopt single-chip microcomputer and D/A converter to produce sine wave in described sine wave, described D/A converter is DAC0832.

The beneficial effects of the utility model: owing to have employed above-mentioned structure, bipolar electrode capacitive transducer of the present utility model is different according to different medium specific inductive capacity between battery lead plate, thus show the principle of different electric capacity in the capacitor, in conjunction with modern microcontroller technology, different capacitance signals is delivered on single-chip microcomputer, the capacitance often organized between pole plate is obtained after the acquisition of single-chip microcomputer inside, calculating, because the size of capacitance is relevant to the material of filling between its pole plate, thus obtain the liquid level of different medium.The utility model can not only carry out Measurement accuracy to single interface level, and the Measurement accuracy that can also realize two or more multiple solutions liquid levels, measuring accuracy is less than 5mm, and there is the abilities such as stronger data processing, real time self-diagnosis, friendly man-machine interaction and easy communication, be equipped with remote transmission module, the function of wireless acquisition system can also be realized.

Accompanying drawing explanation

The utility model is described in further detail to utilize accompanying drawing, but the embodiment in accompanying drawing does not form any restriction of the present utility model, for those of ordinary skill in the art, under the prerequisite not paying creative work, other accompanying drawing can also be obtained according to the following drawings.

Fig. 1 is the composition frame chart of high-precision intelligent multiple solutions liquid level sensor detection system.

Fig. 2 is the structural drawing of bipolar electrode capacitive transducer.

Fig. 3 is the circuit diagram of multiway analog switch module.

Fig. 4 is the interface schema that MCU adopts Atmega16 single-chip microcomputer.

Fig. 5 is the sinusoidal wave circuit diagram that module occurs.

Fig. 6 is the process flow diagram of sinusoidal wave generating program.

Fig. 7 is the circuit diagram of leakage resistance measurement module.

Fig. 8 is the circuit diagram of phase difference detection module.

Fig. 9 is phase difference detection program flow diagram.

Figure 10 is phase type capacitance detecting principle schematic.

Embodiment

The technical solution of the utility model is understood better in order to make those skilled in the art, below in conjunction with the drawings and specific embodiments, the utility model is described in further detail, it should be noted that, when not conflicting, the feature in the embodiment of the application and embodiment can combine mutually.

As shown in Figure 1, high-precision intelligent multiple solutions liquid level sensor detection system described in the utility model, comprise power module, MCU, the sine wave generation module be connected with MCU, with sine wave, the multiway analog switch module that module is connected, the segmented capacitive interface be connected with multiway analog switch module occur with MCU, also comprise the temperature sensing 18B20 module, serial communication interface module, the human-machine interface module that are connected with MCU.Leakage resistance measurement module and phase difference detection module is connected between described MCU and multiway analog switch module; Described segmented capacitive interface is connected to bipolar electrode capacitive transducer, described MCU controls multiway analog switch module and the link of each section of electric capacity in segmented capacitive is connected to sine wave generating circuit by a charging resistor, and output terminal is connected respectively to leakage resistance measurement module and phase difference detection module.

As shown in Figure 2, described bipolar electrode capacitive transducer is wrapped in the symmetry electrode 2 on insulcrete 1 by insulcrete 1, symmetry, and this insulcrete is long is 60mm for 100mm is wide, and the end of symmetry electrode 2 is connected with segmented capacitive interface by electrode 3.Insert between symmetry electrode after in different liquids and namely show different capacitance, this capacitance sends into multiway analog switch module by electrode.Concrete, these capacitive transducers heap poststack insulation rod is fixed as one group, inserts in fluid to be measured, in the electrode access multiway analog switch module of each sensor, send into MCU by A/D converter.

As shown in Figure 3, the multiway analog switch module in native system adopts chip CD4051.CD4051 is numerically controlled 8 path analoging switch, and it has very low conduction impedance and closes leakage current.If its VDD pin is met+5V, VEE pin meets-5V, VSS pin ground connection, and so during conducting, CD4051 is just the analog voltage of-5V ~+5V by scope.So, using CD4051 as multiway analog switch module, the needs of native system can be met.

As shown in Figure 4, described MCU (microcontroller) is ATmega16 single-chip microcomputer, and inside is integrated with A/D converter and an analog comparator on 10,8 tunnel, for this sensing system, both saves space, and in turn saves cost.And the module that single-chip microcomputer is inner integrated, soft and hardware develops also very convenient.

As shown in Figure 5, there is module and adopt single-chip microcomputer and D/A converter to produce sine wave in described sine wave, described D/A converter is DAC0832, and its principal feature has: the D/A converter of 8 parallel port inputs; Double buffering, single buffer or straight-through digital signal input form; The interface of compatible multiple microcontroller; Current mode exports, and the Time Created of electric current is 1us; Owing to being that current mode exports, by means of operational amplifier, current signal must be converted to corresponding voltage signal.Sample with certain frequency offset of sinusoidal function, the point obtained sampling is converted into corresponding digital quantity, then delivers in D/A converter with certain frequency by these points, just completes sinusoidal wave generation.The process flow diagram of program as shown in Figure 6.

As shown in Figure 7, described leakage resistance measurement module is used for the measurement of leakage resistance in parallel model, to improve precision.The way adding DC voltage can be adopted.DC voltage is added in charging resistor and measured capacitance, utilizes A/D converter to measure electric capacity both end voltage, just according to simple resistant series rule, the size of leakage resistance can be calculated.

0-7 pin receiving electrode 3 in Fig. 3 in CD4051 multiway analog switch module, be exactly testing capacitance place in circuit, receiving on the OUT/IN terminal of Fig. 3 _ CD4051 after sine wave access measuring resistance R, the common port of multi-way switch is pin COMOUT/IN, charging resistor is connected to this pin.The multiplexer channel of switch is CHANNELIN/OUT0-7, receives on sectional capacitance by this 8 paths, and each passage connects one section of electric capacity.Sheet selects pin to be INH, and when INH is " 1 ", each passage is all disconnected.Channel selecting pin is A, B, C, arrange according to the order of CBA, 8 kinds of selections can be had, correspond to the conducting of 8 passages.Such as CBA is " 000 ", then pin COMOUT/IN and passage 0 conducting, if CBA is " 001 ", pin COMOUT/IN and passage 1 conducting, so analogize.Thus, control CD4051 multiway analog switch module chip, only need 4 of single-chip microcomputer pins just passable, this will save more multiple resource than the multi-way switch realized with electromagnetic relay.

The sectional capacitance hop count that system is chosen is 8 sections, if be greater than 8 sections that a slice CD4051 provides, so just relates to the problem of CD4051 multi-chip expansion.The design of this chip fully takes into account this point, and its expansion is very convenient, expansion a slice CD4051, as long as a pin taken out by single-chip microcomputer more, to make the chip selection signal line of extended chip just passable, channel selecting line A, B, C can be general.

In fact, INH also can be regarded as channel selecting line, a pin of single-chip microcomputer is directly received on the INH pin of a CD4051, receives on the INH pin of another CD4051 by phase inverter simultaneously, like this, just can according to the combination selector channel of INH, C, B, A.

But the problem that should be noted that is, introduce such multiway analog switch module, the distributed capacitance that certainly will will increase on circuit, this point can not be ignored, and will consider fully when error analysis.The program of multi-path choice module is fairly simple, only needs to select chip and selector channel two steps just to complete.

Then this circuit is connected with MCU.Wherein PA0, PA1, PA2 of MCU connect C, B, A mouth of multi-way switch respectively, as gating signal.The sheet that PA6 connects multi-way switch selects pin INH.PA3, PA4, PA5 meet stand-alone keypad key1, key2, key3 respectively.PA7 is an important pin in the design, connects, and can use its A/D translation function with the common interface of PB2, charging resistor, multi-way switch.PB0, PB1, PB5, PB6 connect 1,2,3,4 of 7SEG-MPX4-CA, select as position.PB2 meets PA7, PB3 ground connection, be used for trigger simulation comparer interrupt.PB4 connects a LED lamp, only uses when debugging.PB7 connects DAC0832's pin, as write enable signal.PC mouth meets the data input pin DIO-DI7 of DAC0832, transmits data.PD mouth meets 7SEG-MPX4-CA, selects signal as section.AREF and AVCC connects+5V power supply.

In Fig. 5, MCU is ATMega16, is main control chip, and its PC pin meets the data input pin DIO-DI7 of D/A converter DAC0832.DAC0832 has four to control pins, and they are chip select pin CS, digital input amount enable pin ILE, write enable WR1 and WR2.By direct for CS and WR2 pin ground connection, ILE pin is directly received on positive 5V power supply, only retains WR1 as control line.Pin Vref is reference voltage input terminal, receives on positive 5V power supply.

The output line of DAC0832 has three, and Rfb is operational amplifier feedback line, receives the output terminal of operational amplifier.Lout1 and Iout2 is two analog current output lines.Lout1+Iout2 is a constant: if input digital quantity is all " 1 ", then lout1 is maximum, and Iout2 is minimum; If input digital quantity is all " 0 ", then loutl is minimum, and lout2 is maximum.In order to ensure the linearity of output current under nominal load, the current potential on lout1 and Iout2 pin must be tried one's best closely level, therefore this two pin is received the input end of amplifier, by Iout2 ground connection.Actual choose resistance R1, R2 and R3 time it should be noted that their selection directly has influence on the quality producing waveform, should choice accuracy higher grade resistance.

The detection method of phase differential is, by analog comparator, sine wave is converted to square wave, and the phase differential of square wave can realize simply by interrupt mechanism.ATmegal6 is integrated with an analog comparator.The value of analog comparator to the value of positive pole AINO and negative pole AIN1 compares.When the voltage on the voltage ratio negative pole AIN1 on AINO is wanted high, the output ACO of analog comparator and set.The output of comparer can be used to the input capture function of shot timers/counter 1.In addition, comparer also can trigger that oneself is proprietary, independently interrupt, and interrupt mode can select rising edge, negative edge or level to change.

The signal wiring of analog comparator only need AIN1 pin ground connection, and AINO pin receives the common port of MUX.Phase difference detection module circuit diagram as shown in Figure 8.

The software flow pattern of phase difference detection as shown in Figure 9.This section of program can be described as: selected same starting point.Close multi-way switch and do not connect testing capacitance, measure the moment t0 that first negative edge arrives.Open multi-way switch and connect first testing capacitance, measure the moment t that first negative edge arrives.Two times do difference, just obtain the waveform delay time on first testing capacitance.Switch multiway analog switch module, successively each section of electric capacity is detected.

Phase type capacitance detecting ratio juris as shown in Figure 10.Cx and Rx is the leakage resistance of testing capacitance and electric capacity, and resistance R is charging resistor.Add a sinusoidal excitation voltage Ui at input end, to meet with a response voltage U o at output terminal, according to general knowledge, we know, Uo is also a sine wave, just amplitude and phase place comparatively Ui change to some extent.Phase type capacitance detecting method detects the difference of input and output two waveforms just to obtain the size of testing capacitance Cx.

Obtain phase differential and leakage resistance, just can calculate the value of testing capacitance.But if will be applied in reality, this capacitance utilizing this method to measure not is the capacitance of section accurately that we need, wherein also has certain error.

Actual capacitance error mainly comprises two aspects, is first the distributed capacitance on wire.Distributed capacitance in circuit version is very little, negligible.But be connected to sectional capacitance upper conductor from multi-way switch all very long, the distributed capacitance that these wires produce be can not ignore, it is the main source of distributed capacitance.

The source of stray capacitance mainly charging resistor and multiway analog switch module in circuit, the stray capacitance in charging resistor is smaller compared with multi-way switch.The data of consulting multiway analog switch module CD4051 is known, and it has in the stray capacitance often produced on the way more than 6-7 pico farad, and when measuring the liquid level of the smaller liquid of some specific inductive capacity, capacitance to be measured is even also little than this stray capacitance.

Analyze above-mentioned two main capacitance errors can find, these electric capacity are all in parallel with measured capacitance.Each measurement, the value of these distributed capacitance and stray capacitance is all fixing, and is be added on testing capacitance simply, can not cause the non-linear of measurement result.

There is above-mentioned cognition, so just can eliminate these errors by the following method: a passage of unsettled multiway analog switch module, its outside has only connected wire, does not connect testing capacitance.So on this paths, except not having testing capacitance, other capacitance error is all involved enters.The capacitance on this road is detected, just can obtain distributed capacitance and stray capacitance and, namely total error sum.Each passage being measured the capacitance obtained, deduct the error this passage measured and obtains, is exactly actual Segmented electrical capacitance.

Set forth a lot of detail in description above so that fully understand the utility model, but the utility model can also adopt other to be different from other modes described here and implement, and therefore, can not be interpreted as the restriction to the utility model protection domain.

In a word; although the utility model illustrates above-mentioned preferred implementation; but should illustrate; although those skilled in the art can carry out various change and remodeling; unless such change and remodeling deviate from scope of the present utility model, otherwise all should be included in protection domain of the present utility model.

Claims (5)

1. a high-precision intelligent multiple solutions liquid level sensor detection system, comprise power module, MCU, the sine wave generation module be connected with MCU, with sine wave, the multiway analog switch module that module is connected, the segmented capacitive interface be connected with multiway analog switch module occur with MCU, between described MCU and multiway analog switch module, be connected to leakage resistance measurement module and phase difference detection module; It is characterized in that: described segmented capacitive interface is connected to bipolar electrode capacitive transducer, described bipolar electrode capacitive transducer is wrapped in the symmetry electrode (2) on insulcrete (1) by insulcrete (1), symmetry, the end of symmetry electrode (2) is connected with segmented capacitive interface by electrode (3).

2. high-precision intelligent multiple solutions liquid level sensor detection system according to claim 1, is characterized in that: also comprise the temperature sensing 18B20 module, serial communication interface module, the human-machine interface module that are connected with MCU.

3. high-precision intelligent multiple solutions liquid level sensor detection system according to claim 1, is characterized in that: described multiway analog switch module is integrated multiway analog switch module chip CD4051.

4. high-precision intelligent multiple solutions liquid level sensor detection system according to claim 1, is characterized in that: described MCU is ATmega16 single-chip microcomputer, the A/D converter on integrated 10,8 tunnel and an analog comparator.

5. high-precision intelligent multiple solutions liquid level sensor detection system according to claim 1, is characterized in that: described sine wave module occurs and adopts single-chip microcomputer and D/A converter to produce sine wave, and described D/A converter is DAC0832.