CN2355327Y - Water content measurer - Google Patents

Abstract

The utility model relates to a water content measurer for materials, which is composed of a probe, a converter and a measuring display, wherein the probe is a component, the capacitance CX of which can be changed according to different water contents of the material sensed by the probe, the converter is an imaginary part method capacitance measuring circuit, the output voltage UO of which is directly proportional to the angular frequency omega of the input voltage UI and the measured capacitance CX, all levels of stabilized power supply can be supplied by the measuring display and the measuring display which comprises a circuit which can provide frequency stabilized input voltage signal UI for the converter and can measure and display the measured value. The utility model is used for the quick, accurate, real-time, on-site and non-destructive inspection to the water content of the foodstuff of bulk packing, bag packing and basket packing or other fine materials.

Description

The material aquametry apparatus

A kind of measurement instrument that detects institute's water content amount in the material, belong to non-electricity measure instrument category, when being specially adapted to grain purchases the water percentage of in bulk, basket dress, bagged grain is done scene, real-time, Non-Destructive Testing, also can be used for the water percentage of fine granularity materials such as flour, milk powder or coal dust, breeze is done on-the-spot, detection in real time.

Mostly the detection of existing grain moisture content is to bite grain into pieces according to tester's experience, makes qualitative evaluation with " crisp " sense; Or with weigh-dry-method of weighing again quantitatively examines and determine the water percentage of material, there is the gross error of human factor in the former, there is slow, the inefficient problem of speed in the latter.Measure with microwave method, though good linearity, the cost height.Electric capacity succusion, pulverizing measuring resistance method detect moisture content and then exist linear poor, problems such as stability is bad, real-time difference.

Task of the present utility model be based on " imaginary part method capacitance measurement circuit " design a kind of can in bulk, basket dress, packed grain or other fine granularity material water ratio carry out the scene, in real time, fast, accurately, the material aquametry apparatus of Non-Destructive Testing.

The utility model is realized as follows.

Its principle of work is, based on glassware for drinking water the grain of ratio is arranged, flour, the mineral powder has higher dielectric coefficient, and the dielectric coefficient of the medium between the electric capacity between the electrode and the electrode is directly proportional, when materials such as grain are filled between electrode, the low materials such as grain of material ratio water percentage such as grain that water percentage is high have higher dielectric coefficient, thereby make interelectrode electric capacity when filling the high materials such as grain of water percentage, than filling the low materials such as grain of water percentage bigger electric capacity is arranged, the metering circuit that is directly proportional with electric capacity by a kind of output voltage, the variation of the inter-electrode capacitance that the water percentage of materials such as grain is directed at is converted to voltage, measure this voltage with digital voltmeter again, by calibrate, then can measure the water percentage of materials such as grain.

The utility model is made up of probe, transducer and measurement-display.Probe is that to be felt material water ratio different and send a telegraph the capacitive device that holds the CX linear change; Transducer is that a kind of its output voltage U O is proportional to input voltage UI, angular frequency and measured capacitance CX, relational expression is UO=j ω RFCXUI " an imaginary part method capacitance measurement circuit "; Measurement-display then be can provide working powers at different levels to circuit, provide to transducer frequency stabilization input voltage signal UI contain links such as filtering, detection, resonance-amplifier, energy measurement shows the circuit of tested value.Probe, transducer, measurement-display are realized being electrically connected accordingly between them with lead or cable and connection terminal.

Be described in further detail below in conjunction with accompanying drawing:

Probe of the present utility model contains by the core bar 1 of band cylinder and conehead, is probe portion and handle 4 that the columnar measurement utmost point 2 of shoulder and the handle utmost point 3 constitute.Core bar, the measurement utmost point and handle utmost point coaxial cable are nestable successively, with the filling of high strength insulating gel, the ground splicing of insulating is integral, and between the conehead columnar portion end face of the big end end face of the maintenance measurement utmost point 2 and core bar 1, and the spacing that 5-10mm is arranged between minimum end end face of handle and measurement utmost point shoulder end face.The other end then keeps core bar successively than measuring the utmost point, measure the ultimate ratio handle utmost point stretch out vertically 3-5mm as electric contact so that welding lead, the handle utmost point 3 connects with handle 4.Converter circuit 5 is arranged in the cavity of handle 4 inside.The electric contact of each electrode of probe is connected through lead and transducer are corresponding, the electric contact A1 of core bar 1, the handle utmost point 3 wherein, and the equal ground connection of A3 becomes the potential pole of capacitor C X.The measurement utmost point 2 is connected to transducer electrical connection place accordingly as another utmost point of detected capacitor C X through electric contact A2.The core bar awl end face of cylinder, measure greatly the end face of cylinder and the minimum end of the handle face of cylinder directly through identical, be 6-10mm, measuring and greatly holding face of cylinder length is 40-150mm, and core bar awl end face of cylinder length and the minimum end of handle face of cylinder length are for measuring the 3/5-2/3 of very big end face of cylinder length.The external coated high-strength abrasion-proof material of whole probe (referring to accompanying drawing 1).

Fig. 2 shows the converter circuit structure, and transducer 5 contains amplifier NO:A-NO:D, resistor R F, RO, RO1-RO4, capacitor CO2 and capacitor C I.Be " the imaginary part method capacitance measurement circuit " of a kind of output voltage U O series value of being proportional to input voltage UI, angular frequency, feedback resistance RF and capacitor C I and measured capacitance CX.Wherein, the positive input terminal INP of NO:A fetches the excitation AC signal UI from measurement-display, its negative input end connects its output terminal and makes follower, its output connects the positive input terminal of amplifier NO:B, the NO:B negative input end connects output terminal by feedback resistance RF, the negative input end of NO:B also meets capacitor CI, and the other end of capacitor C I connects the measurement utmost point 2 of probe nearby with hard lead through terminal A2; The output terminal of the positive input termination NO:A of NO:C, the negative input end of NO:C connects its output terminal through resistance R O and makes " phase shift compensation follower "; The output terminal of NO:C connects the negative input end of NO:D through resistance R O1, and the negative input end of NO:D also connects its output terminal through resistance R O2; The output terminal of NO:B connects the positive input terminal of NO:D, the positive input terminal connecting resistance RO4 of NO:D, another termination capacitor C O2 of RO4, the other end ground connection of CO2 through resistance R O3; The output terminal of NO:D is exported the figure signal of this transducer to measurement-display.The ground wire of circuit (GND) meets the core bar 1 of probe, electric contact A1, the A3 of the probe handle utmost point 3 nearby with hard lead, and the electric contact A2 that measures the utmost point 2 is connected with capacitor C I one utmost point.

And RO=RF is arranged, so that reach the amplifier of NO:B and these two amplifiers formations of NO:C essentially identical phase shift is arranged.In order to make NO:D become a subtraction circuit, and make RO1=RO2, RO3=RO4, and make RO1=RO2=RO3=RO4 as far as possible the output signal of NO:C and NO:B.

Like this, this circuit is with following principle work:

The output of NO:A equals the input UI of NO:A.

The output UO of subtraction circuit, the output UC's of the output UB of NO:B and NO:C is poor just: $\mathrm{UO}=\mathrm{UB}\&times;\frac{\mathrm{<figure-callout\; id="4"\; label="RO"\; filenames="Y9823157900101.png,Y9823157900111.png"\; state="\{\{state\}\}">RO</figure-callout>}4}{\mathrm{<figure-callout\; id="3"\; label="RO"\; filenames="Y9823157900101.png,Y9823157900111.png"\; state="\{\{state\}\}">RO</figure-callout>}3+\mathrm{<figure-callout\; id="4"\; label="RO"\; filenames="Y9823157900101.png,Y9823157900111.png"\; state="\{\{state\}\}">RO</figure-callout>}4}\&times;(1+\frac{\mathrm{<figure-callout\; id="2"\; label="RO"\; filenames="Y9823157900101.png,Y9823157900111.png"\; state="\{\{state\}\}">RO</figure-callout>}2}{\mathrm{RO}1})-\mathrm{UC}\&times;\frac{\mathrm{<figure-callout\; id="2"\; label="RO"\; filenames="Y9823157900101.png,Y9823157900111.png"\; state="\{\{state\}\}">RO</figure-callout>}2}{\mathrm{<figure-callout\; id="1"\; label="RO"\; filenames="Y9823157900101.png,Y9823157900111.png"\; state="\{\{state\}\}">RO</figure-callout>}1}$ $=\mathrm{UB}\&times;\frac{1}{2}\&times;(1+1)-\mathrm{UC}\&times;\frac{1}{1}$ ＝UB-UC

When NO:B does not have measured capacitance over the ground, that is the negative input end that is equal to NO:B is not when having electric capacity, then the output signal of NO:B and NO:C be homophase, with the width of cloth, i.e. UB=UC.Subtracter NO:D is output as UO=0.

And when the negative input end of NO:B had over the ground measured capacitance CX (establishing CI be very big numerical value with respect to CX, so there is the connect value of CX of CI to be similar to CX), it was output as: $\mathrm{UB}=\mathrm{UI}(1+\frac{\mathrm{<figure-callout\; id="1"\; label="RF"\; filenames="Y9823157900101.png,Y9823157900111.png"\; state="\{\{state\}\}">RF</figure-callout>}}{1/\mathrm{j\&omega;CX}})=\mathrm{UI}(1+\mathrm{j\&omega;}\&bull;\mathrm{RF}\&bull;\mathrm{CX})$

The output of NO:C then is:

UC＝UI

Therefore, the output of subtraction circuit NO:D is:

UO＝UB-UC＝jω·RF·CX·UI

Thereby the output function that has determined this translation circuit is the linear function that is proportional to the series value of input voltage UI, angular frequency, feedback resistance RF and capacitor C I and measured capacitance CX.Circuit guarantees that with reliable measure ω, RF are constant, and then measurement output is only relevant with UI, CX.

The circuit of measurement-display contains excitation signal generator 11, anti-interference filter 12, wave detector 13, subtraction resonance-amplifier 14, digital voltmeter 15, electric power source distribution device 16 and battery 17.As Fig. 3.

Excitation signal generator 11 output frequencies, the sine wave of amplitude stabilization is received the terminal INP of the transducer 5 that is installed in the probe handle 4 again through cable through terminal B1 output, the input of anti-interference filter 12 meets the output OUT of transformation into itself's device 5 through cable, after wave filter 12 filtering interfering, deliver to absolute average wave detector 13, the direct current signal of detection output is delivered to subtraction resonance-amplifier 14, the level value of the initial capacitance correspondence when subtraction resonance-amplifier 14 deducts probe and is arranged in air, and the signal that will amplify after regulating outputs to digital voltmeter 15, the water percentage of demonstration tested material.The single supply that battery 17 provides, provide required circuit to use through electric power source distribution device 16 generation VDD, VREF, VCC, GND, VCC equals the 40%-60% of cell voltage VDD, and the VREF that exceeds the 1/8-1/10 of cell voltage with respect to VCC makes normal voltage for digital voltmeter.

Allow the measurement utmost point of probe that initial capacitance (electric capacity that probe is arranged in absolutely dry material adds the natural capacity of probe) is arranged over the ground in the design, deduct the value of this electric capacity correspondence with the absolute average after 14 pairs of detections of subtraction resonance-amplifier, make digital voltmeter be shown as O; Then after rapier inserts material, when making the electric capacity increment because of the water percentage increase, the voltage of subtracter output will be proportional to water percentage with certain linearity and increase, thereby realize the linear measurement of water percentage.

Therefore, this drimeter has, and when the increment of material water ratio caused measurement linearly extremely to the capacitance increase of earthing pole, the output voltage increment of amplifier 15 was proportional to the increment of electric capacity linearly, thereby is proportional to the water cut of material linearly.

The excitation signal generator 11 of this measurement display is by forming the peak-to-peak value of oscillator-output of frequency divider generation very near the frequency stabilization symmetrical square wave of power vd D to GND with VDD to the cmos circuit and the crystal of GND power supply, frequency is f0, then by a fixed gain, enlargement factor be about 1/20-1/10, its corner frequency for (1.5-2) f0, guarantee that the reference level of output is " the pumping signal low-pass filter " of the average level of CMOS oscillator output waveform, be converted to a sine wave.

Fig. 4 is the circuit of an embodiment, produce the vibration of frequency stabilization with the devices such as crystal Z1 of D1 (CD4060) and 32768Hz, by the D1 frequency division, by its Q4 output f0=2048Hz symmetrical square wave, D1 powers to GND with VDD, alleviate the load of frequency division output terminal Q4, its output amplitude extremely approaches VDD to GND as far as possible.Form described " pumping signal low-pass filter " by R3-R7, R7 ', C4-C7, amplifier N2:C, exchange first resistance that composes in parallel 3 rank low-pass filter circuits with R6 by R3, and with R4-R7, R7 ', capacitor C4-C6, amplifier N2:C form the pumping signal low-pass filter of described requirement.Because R6, R7 exchange through C7 and meet GND, the reference level that does not influence N2:C output equals the average level of Q4 output, and being beneficial to transducer has maximum dynamic range.

The N2:A of Fig. 4, N2:B and resistance R 14, R16, R18, C17 form the electric power source distribution device 16 of VCC and digital voltmeter normal voltage VREF, its output voltage V CC, and as the reference level of aftermentioned circuit, VREF is as the benchmark of digital voltmeter.

N1:A, R21-R23, capacitor C 21, C22, composition anti-interference filter 12 to reject the interference that transducer receives, mainly are that power frequency is disturbed and Electromagnetic Interference.The positive input termination VCC of N1:A, purpose is that to make its filtering output strictly be benchmark with VCC.

N1:B, N1:C, resistance R 9-R11, diode V1, V2 form negative output absolute average wave detector 13, with VCC is benchmark, and AC signal transducer, that export through anti-interference filter 12 filtering is converted to negative direct current (pulsation) voltage signal of making benchmark with VCC.

N1:D, R12, R13, R17 and RP1, RP2 form subtraction resonance-amplifier 14, it is a shunt voltage negative-feedback amplifier, be intended to by regulating RP2, when realization is arranged in the probe of transducer in absolutely dry material, the detection negative voltage that has factor affecting face generations such as initial capacitance because of probe, being output as zero by subtraction to N1:D, is zero adjustment as water percentage; And work as probe insertion water percentage is the material of X, when the output of transducer increases, changes anti-phase enlargement factor by regulating RP1, makes a voltage of N1:D output, and the demonstration corresponding to X is arranged on digital voltmeter N3.As: X=20% then regulates RP1 and make N1:D output 0.2V, and the radix point of digital voltmeter is located at kilobit, is shown as 0.200 (V), then represents 20% water percentage.

The output of N1:D is with respect to VCC, and the IN+ of digital voltmeter N3 connects the output of N1:D, and the IN-of digital voltmeter meets VCC.Use simultaneously through voltage N2:B output, that get by the battery supply dividing potential drop and be connected to REF+, as the normal voltage VREF of digital voltmeter.When cell voltage decline Y%, the output of oscillator, transducer and the normal voltage of the digital voltmeter Y% that all descends in succession, thereby zero point of measuring and the advantage that does not descend and become because of cell voltage is arranged for the water percentage displayed value that the material of same water percentage is measured.

Claims (7)

1. a material aquametry apparatus is made up of probe, transducer and measurement-display, and it is characterized in that popping one's head in is that to be felt material water ratio different and send a telegraph the device that holds the CX linear change; Transducer is that a kind of its output voltage U O is proportional to input voltage UI, angular frequency and measured capacitance CX, has relational expression UO=j ω, RF, CX, " the imaginary part method capacitance measurement circuit " of UI; Measurement-display then is can provide each level power supply to circuit, the input voltage signal UI of frequency stabilization is provided to transducer, contains the circuit of filtering, detection, all links of resonance-amplifier, energy measurement, processing, the tested value of demonstration; Probe, transducer, measurement-display are realized electrically connecting accordingly between them with lead or cable and connection terminal.

2. by the described material aquametry apparatus of claim 1, it is characterized in that popping one's head in and contain core bar (1) by band garden post and conehead, be the probe portion of the columnar measurement utmost point of shoulder (2) and the handle utmost point (3) formation, and handle (4); Core bar, the measurement utmost point and handle utmost point coaxial cable are nestable successively, be connected into one with high strength insulating gel filling insulating gel, and between the conehead columnar portion end face of the big end end face of the maintenance measurement utmost point (2) and core bar (1), and the spacing that 5-10mm is arranged between minimum end end face of handle and measurement utmost point shoulder end face, the other end then keeps core bar successively than measuring the utmost point, measures the ultimate ratio handle utmost point and stretches out 3-5mm vertically; The handle utmost point (3) connects with handle (4); Converter circuit (5) is arranged in the inner cavity of handle (4), the electric contact of each electrode of probe connects through lead and transducer are corresponding, wherein core bar (1) becomes the earth potential utmost point of capacitor C X through joint A1, the handle utmost point (3) through joint A3 ground connection, measures the utmost point (2) and is connected to contact place, the corresponding Electricity Federation of transducer as another utmost point of detected capacitor C X through electric contact A2

3. by the described material aquametry apparatus of claim 2, it is characterized in that the core bar conehead face of cylinder, measure the equal 6-10mm of being of the straight warp of greatly holding the face of cylinder and the minimum end of the handle face of cylinder, measuring greatly, end face of cylinder length is 40-150mm, the length on the core bar conehead face of cylinder length and the minimum end of the handle face of cylinder is for measuring the greatly 3/5-2/3 of end face of cylinder length, detecting probe surface coating high-strength abrasion-proof insulating material.

4. according to claim 1 or 2 or 3 described material aquametry apparatus, it is characterized in that converter circuit (5), contain amplifier NO:A-NO:D, resistor R F, RO, RO1-RO4, capacitor CO2 and capacitor C I, the positive input terminal INP of NO:A fetches the excitation AC signal UI from measurement-display, its negative input end connects its output terminal and makes follower, its output connects the positive input terminal of amplifier NO:B, the NO:B negative input end connects output terminal by feedback resistance RF, the negative input end of NO:B also meets capacitor CI, and the other end of capacitor C I connects the measurement utmost point (2) of probe nearby with hard lead through terminal A2; The output terminal of the positive input termination NO:A of NO:C, the negative input end of NO:C connects its output terminal through resistance R O and makes " phase shift compensation follower "; The output terminal of NO:C connects the negative input end of NO:D through resistance R O1, and the negative input end of NO:D also connects its output terminal through resistance R O2; The output terminal of NO:B connects the positive input terminal of NO:D, the positive input terminal connecting resistance RO4 of NO:D, another termination capacitor C O2 of RO4, the other end ground connection of CO2 through resistance R O3; The output terminal of NO:D is exported the figure signal of this transducer to measurement-display; The ground wire of circuit connects the core bar (1) and the handle utmost point (3) of probe nearby with hard lead.

5. by the described material aquametry apparatus of claim 4, it is characterized in that measuring-circuit of display contains excitation signal generator (11), anti-interference filter (12), wave detector (13), subtraction resonance-amplifier (14), digital voltmeter (15), electric power source distribution device (16) and battery (17); Excitation signal generator (11) output frequency, the sine wave of amplitude stabilization is received the terminal INP that is installed in the transducer (5) in the probe handle (4) through cable again through terminal B1 (1) output, the input B2 of anti-interference filter (12) meets the output OUT of transformation into itself's device (5) through cable, after wave filter (12) filtering interfering, deliver to absolute average wave detector (13), the direct current signal of detection output is delivered to subtraction resonance-amplifier (14), the level value of the initial capacitance correspondence when deducting probe and being arranged in air, and the signal that will amplify after regulating outputs to digital voltmeter (15), the single supply that battery (17) provides, produce VDD through electric power source distribution device (16), VRE, VCC, GND uses for each circuit, VCC equals the 40%-60% of cell voltage VDD, and the voltage that exceeds with respect to VCC is that the VREF of cell voltage 1/8-1/10 makes normal voltage for digital voltmeter.

6. by the described material aquametry apparatus of claim 5, the excitation signal generator (11) that it is characterized in that its measurement-display contain one with VDD to the symmetrical square wave GND power supply, that can outputting stable frequency be f0 and peak-to-peak value extremely approach power vd D to oscillator-frequency divider GND, that forms by cmos circuit and crystal and a fixed gain, enlargement factor be 1/20-1/10, its corner frequency is the low-pass filter of the average level of CMOS oscillator output waveform for reference level (1.5-2) f0, that assurance is exported.

7. according to claim 5 or 6 described material moisture measuring instruments, it is characterized in that forming respectively the vibration-frequency divider and the pumping signal low-pass filter of excitation signal generator (11) with D1 (CD4066), crystal Z1 and resistance R 3-R7, R7 ', capacitor C4-C7, amplifier N2:C, oscillator-frequency divider is by the D1 frequency division, power to GND with supply voltage VDD, the symmetrical square wave of its Q4 output frequency f0, the third-order low-pass filter circuit conversion of forming via above-mentioned device is sinusoidal wave, is exported to the terminal INP of transducer (5) by N2:C; Form electric power source distribution device (16) by amplifier N2:A, N2:B, resistance R 14, R16, R18 capacitor C 17, export the reference level VCC that uses for the aftermentioned circuit respectively and be made for the normal voltage VREF that digital voltmeter (15) uses by amplifier N2:A, N2:B; Form anti-interference filter (12) by amplifier N1:A, R21-R23, capacitor C 21, C22, the positive input termination VCC of its N1:A; Form negative output absolute average wave detector (13) by N1:B, N1:C, resistance R 9-R11, diode V1, V2, with transducer (5), to be converted to VCC through the AC signal of anti-interference filter (12) filtering output be that the negative dc pulse moving voltage signal of benchmark exports resonance-amplifier (14) to; Be connected into a shunt voltage negative-feedback amplifier by amplifier N1:D, resistance R 12, R13, R17, RP1, RP2 and form subtraction resonance-amplifier (14), amplifier N1:D has initial voltage to be output as the magnitude of voltage output of zero-sum corresponding to material water ratio, its output is connected to the IN+ of digital voltmeter (15), digital voltmeter IN-meets VCC, and REF+ meets the VREF of N2:B output in the electric power source distribution device.

Images