CN202710503U

CN202710503U - Four-electrode electrical conductivity sensor

Info

Publication number: CN202710503U
Application number: CN2012201848160U
Authority: CN
Inventors: 李学胜; 卢欣春; 罗孝兵; 刘冠军; 王军涛; 袁颖华
Original assignee: NARI Group Corp; State Grid Electric Power Research Institute
Current assignee: NARI Technology Co Ltd; State Grid Electric Power Research Institute; State Grid Corp of China SGCC
Priority date: 2012-04-27
Filing date: 2012-04-27
Publication date: 2013-01-30
Anticipated expiration: 2022-04-27

Abstract

The utility model discloses a four-electrode conductivity sensor, which has an upper shell and a lower shell, the upper shell is processed with wire holes, the lower shell is processed into an empty shell, and the integrally processed electrodes contain two current electrodes and two voltage electrodes. Before potting, the electrodes are fixed by electrode fixing parts, and then fixed to the lower case by pins. The lower case is provided with a wire fixing ring, so that the wires will not shake randomly during the potting process, reducing open circuit Rate. The electrode of the utility model adopts graphite as a material for overall processing, is easy to process, and is cheap in price, can accurately ensure the symmetry of each electrode, and improves the measurement accuracy. The conductivity sensor has the characteristics of high measurement accuracy, low environmental pollution resistance, good instrument stability, simple structure, low cost, and long service life.

Description

Four electrode conductivity sensors

Technical field

The utility model relates to a kind of conductivity sensor of measuring solution ion concentration, particularly a kind of four electrode conductivity sensors.

Background technology

Conductivity sensor mainly contains two kinds of mode of operations, induction type and electric pole type, main employing is electric pole type at present, what traditional conductivity sensor adopted is two electric pole types, when measuring for two electrode conductivity sensors, add the voltage signal of uniform amplitude between two electrodes, certain electric current of flowing through on the electrode, size of current depends on the quantity of contained ion in the solution.In this two electrode technology measuring processes, electrode is galvanic electrode, is again voltage electrode.In fact, as long as have electric current to pass through on the electrode, will produce polarizing voltage on the surface of contact of solution and electrode, make to measure to produce certain error.

Four electric pole type conductivity sensors are focuses of studying both at home and abroad at present, and four electrode conductivity sensors mainly are comprised of electronic surveying unit and four electrode conductance ponds.Independently galvanic electrode and voltage electrode can be eliminated the error that polarization is brought in the solution measuring process in the four electrode method.

At present, the electrode of report four electrode conductivity sensors is comprised of platinum round dot group on the document, galvanic electrode is that a diameter is the platinum cylinder of 2mm, and voltage electrode is formed by one group of platinum round dot that the center of circle distributes take galvanic electrode, forms because galvanic electrode is some discrete points, therefore be difficult for arranging, and platinum soaks in sewage solution for a long time, measures, and easily is corroded, comes off, and often carry out wiping, and platinum is not easy processing, and is expensive.The Inorganic Non-metallic Materials that the electrode supporting plate adopts and the expansion coefficient of electrode material metal platinum have very big difference, bring very large difficulty for sintering and encapsulation.The electrode supporting plate adopts open, and through placing for a long time, corroding, back up pad easily deforms, and is difficult to guarantee the constancy of cell constant of conductometric vessel.

The utility model content

In order to solve the problems of the prior art, the utility model provides a kind of four novel electrode conductivity sensors, and the electrode of this sensor is that the fine and close graphite of employing is material.Graphite is easily processed, low price.Electrode adopts whole processing, can accurately guarantee the symmetry of each electrode.Graphite and the encapsulation liquid that adopts have the expansion coefficient that approaches very much, and electrode and encapsulating housing are not easily separated when being subject to temperature variation.Further, the utility model provides a kind of effective solution for the discharge of bubble in the encapsulation process.In a word, the utility model can provide a kind of conductivity sensor, and it has, and high, the anti-environmental pollution of measuring accuracy is little, stability of instrument good, characteristics simple in structure, with low cost.

In order to achieve the above object, the technical scheme that adopts of the utility model is:

A kind of four electrode conductivity sensors, comprise upper and lower two housings, in encapsulation process by in housing, pouring into the mixture of epoxy resin and hardening agent, electrode and wire are encapsulated in the housing, it is characterized in that: be provided with the wire set collar in lower house, described wire set collar limits the layout trend of wire in lower house.

Described four electrode conductivity sensors is characterized in that: described electrode material is graphite.

Described four electrode conductivity sensors is characterized in that: described electrode comprises cylindric galvanic electrode and is placed in the outer ring-type voltage electrode of described cylindric galvanic electrode.

Described four electrode conductivity sensors is characterized in that: described electrode is fixed by electrode fixuture, and described electrode fixuture is fixed in the inside ghost of lower house by the pin that radially passes the lower house shell wall.

Described four electrode conductivity sensors is characterized in that: described electrode integral processes, and by secondary processing electrode is divided into independently four after encapsulation, two galvanic electrodes and two voltage electrodes.

Described four electrode conductivity sensors is characterized in that: centered by described pin, mill a straight trough shape through hole at described lower house during secondary processing.

Described four electrode conductivity sensors is characterized in that: be provided with bleeder vent and electrode cable groove on the described electrode.

Described four electrode conductivity sensors is characterized in that: what be used for removing air in the described lower house when also comprising encapsulated electrode vacuumizes vessel and vacuum pump.

Described four electrode conductivity sensors is characterized in that: encapsulation reagent adopts the mixture of 2023 epoxies and 2105c hardening agent, and mixing ratio is 2:1.

The utility model beneficial effect is: the electrode of four electrode conductivity sensors of the present utility model is that the fine and close graphite of employing is material, conveniently processes, reduced cost.Electrode adopts whole processing, can accurately guarantee the symmetry of each electrode.Graphite and the encapsulation liquid that adopts have the expansion coefficient that approaches very much, and electrode and encapsulating housing are not easily separated when being subject to temperature variation.Special packaging technology is more advantageously discharged the bubble in the encapsulation process.The conductivity cell structure of this patent is firm, has guaranteed the constancy of cell constant of conductometric vessel.In a word, this conductivity sensor have that high, the anti-environmental pollution of measuring accuracy is little, stability of instrument good, characteristics simple in structure, with low cost.

Description of drawings

Figure 1A is the utility model measuring principle figure;

Figure 1B is A-A cut-open view among Fig. 1;

Fig. 2 A is external structure schematic diagram after the utility model encapsulation;

Fig. 2 B inner structure schematic diagram of the present utility model;

Fig. 3 is the electrode structure schematic diagram among Fig. 2 B;

Fig. 4 A is that the utility model carries out external structure schematic diagram after the secondary processing;

Fig. 4 B is that the utility model carries out inner structure schematic diagram after the secondary processing.

Embodiment

Below in conjunction with accompanying drawing the utility model is further described.

Shown in Fig. 2 A, Fig. 2 B, four electrode conductivity sensors of the present utility model, it has a upper shell 2 and a lower house 4, is processed with the wire guide 10 that connects to lower house 4 in the upper shell 2, can hold wire 1 in the wire guide 10 and pass.Lower house 4 is processed into ghost 5, and electrode 8 is fixed by electrode fixuture 9, and then the shell wall that is passed lower house by pin 11 is fixed to electrode fixuture 9 in the inside ghost 5 of lower house 4.Wire 1 one ends link to each other with the silver-gilt copper wire ring 7 of lower house 4 interior settings, and the wire guide 10 of the other end in upper shell 2 passes.The unlikely wire 1 that damages during for secondary processing, the layout of wire 1 in lower house 4 is fixed by wire set collar 3, wire 1 links to each other with silver-gilt copper wire ring 7, silver-gilt copper wire ring 7 is fixed on the electrode 8 by electrode cable groove 6, make in the embedding process that wire 1 is unlikely arbitrarily to be rocked, and silver-gilt copper wire ring 7 and electrode 8 are combined firmly, reduce burn out rate.

As shown in Figure 3, be electrode 8 structures among Fig. 2 B, it contains galvanic electrode 82 and voltage electrode 81, be separated into two galvanic electrodes 82 and two voltage electrodes 81 after the secondary processing, accurately symmetrical in twos in order to guarantee secondary processing after-current electrode 82 and voltage electrode 81, adopt whole processing, gap length between galvanic electrode 82 and the voltage electrode 81 is the annulus of 1mm, narrow space, in order to make encapsulation reagent enter annular section between two electrodes, be processed with air hole 84 at electrode, be fixed on the electrode 8 in order to make plain conductor, can be processed with electrode cable groove 6 thereon.

Prepare encapsulation reagent: owing to space between conductivity meter probe inside, the electrode is little, require the epoxy resin viscosity little, just be easy to embedding; Consider conductivity meter environment for use and instrument performance, require simultaneously epoxy resin that the characteristics such as high-adhesive-strength, cure shrinkage is little, chemical-resistance good, electrical insulating property is good, product size is stable, water-intake rate is low are arranged.Epoxy resin adopts the 2023(single-component epoxy compound resin of triple bond company in the present embodiment), hardening agent adopts the 2105c of triple bond company, mixing ratio is 2:1, epoxy resin with stir after hardening agent mixes with proportioning, be put into homemade vacuumizing in the vessel, the bubble that produces in the mixed process is driven out of, in order to guarantee the dilutability of mix reagent, whole process will be finished as early as possible, avoids mix reagent phenomenon to occur solidifying.

Encapsulation process: encapsulate after all parts install, during encapsulation, take off upper shell 2, slowly (make the mix reagent of the epoxy of getting ready in advance and hardening agent the air in the lower house have time enough to discharge) and pour into lower house 4, if until reagent had not just had wire set collar 3(reagent too many, when vacuumizing, gas can be taken reagent out of lower house 4), there is filling the lower house 4 of mix reagent to put into self-control and vacuumizes vessel, the air that is detained in the lower house 4 of rushing.From vessel, take out instrument, continue to inject mix reagent to lower house 4, until fill.Then, lower house 4 is put into slowly heating in the high-low temperature chamber, Temperature Setting is 40 °, for the air that may carry in the mix reagent of adding after driving out of, after 1 hour, take out lower house 4, upper shell 2 is screwed in, reagent in the lower house 4 can be squeezed in the wire guide 10 of upper casing 2 bodies naturally, is full of whole wire guide 10.Again whole sensor is put into high-low temperature chamber, temperature transfers to 60 ° and was heating and curing 2 hours, closes the incubator switch, and it is cooled off naturally, takes out sensor after 24 hours, encapsulates complete.Sensor after the encapsulation is shown in Fig. 2 A, Fig. 2 B.

Sensor shown in Fig. 2 A, Fig. 2 B forms the sensor construction shown in Fig. 4 A, Fig. 4 B through secondary processing.Process is: the pin 11 that takes out first sensor behind the package curing, centered by center, two pins, 11 hole, mill the long 20mm that is at lower house 4, wide is the straight trough mouth through hole 12 of 5mm, this straight trough mouth through hole 12 is the conductance cell of sensor, the electrode 8 of integral body processing is blocked to be divided into four electrodes simultaneously two

galvanic electrodes

82,84, two

voltage electrodes

81,83, and accurately symmetrical in twos.

Below introduce in detail lower measuring principle of the present utility model:

Shown in Figure 1A, Figure 1B, this conductance cell has two cylindric

galvanic electrodes

82,84 and two ring-

type voltage electrodes

81,83, is installed in respectively on the supporting surface of two parallel and insulation.Pass through in the slit of fluid to be measured 100 between two supporting plane galvanic electrodes during measurement.Because the galvanic electrode two ends have applied an AC signal and by electric current, have set up electric field in fluid media (medium), respond to generation voltage by two voltage electrodes.Exchange current by between the control galvanic electrode makes electric current I _cKeep constant, when electrical conductivity of solution changes, the voltage V at voltage electrode two ends _cCorresponding changing.There is certain corresponding relation in the voltage in voltage electrode loop corresponding to the conductivity of detected solution, can try to achieve by the voltage of measuring voltage electrode loop the conductivity of solution according to this relation.Expressed by following formula:

Figure 2012201848160100002DEST_PATH_IMAGE001

In the formula:

C is the fluid to be measured conductivity;

K is cell constant of conductometric vessel;

R _cImpedance for conductance cell;

V _cBe R _cThe pressure drop at two ends (being voltage between the voltage electrode);

I _cBe the electric current by galvanic electrode.

Claims

1. A four-electrode conductivity sensor, comprising upper and lower housings, during the encapsulation process, the electrodes and wires are encapsulated in the housing by pouring a mixture of epoxy resin and curing agent into the housing. The feature is that a wire fixing ring is arranged in the lower casing, and the wire fixing ring limits the arrangement direction of the wires in the lower casing.

2. The four-electrode conductivity sensor according to claim 1, characterized in that: the electrode material is graphite.

3 . The four-electrode conductivity sensor according to claim 2 , wherein the electrodes include a cylindrical current electrode and a ring-shaped voltage electrode set outside the cylindrical current electrode. 4 .

4. The four-electrode conductivity sensor according to claim 3, characterized in that: the electrodes are fixed by electrode holders, and the electrode holders are fixed to the lower case by pins that radially pass through the lower case wall in the inner shell of the body.

5. The four-electrode conductivity sensor according to claim 2, 3 or 4, characterized in that: the electrodes are integrally processed, and after packaging, the electrodes are divided into four independent, two A current electrode and two voltage electrodes.

6 . The four-electrode conductivity sensor according to claim 5 , characterized in that, during secondary processing, a straight slot-shaped through hole is milled on the lower housing with the pin as the center. 7 .

7. The four-electrode conductivity sensor according to claim 5, characterized in that: the electrodes are provided with air holes and electrode lead grooves.

8. The four-electrode conductivity sensor according to claim 2, characterized in that: it also includes a vacuum vessel and a vacuum pump for removing air in the lower housing when packaging the electrodes.