CN101493310B - Cylinder type bidirectional capacitance displacement sensor with across double-window counter electrode structure - Google Patents
Cylinder type bidirectional capacitance displacement sensor with across double-window counter electrode structure Download PDFInfo
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- CN101493310B CN101493310B CN2009100713050A CN200910071305A CN101493310B CN 101493310 B CN101493310 B CN 101493310B CN 2009100713050 A CN2009100713050 A CN 2009100713050A CN 200910071305 A CN200910071305 A CN 200910071305A CN 101493310 B CN101493310 B CN 101493310B
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- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B7/00—Measuring arrangements characterised by the use of electric or magnetic techniques
- G01B7/12—Measuring arrangements characterised by the use of electric or magnetic techniques for measuring diameters
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B7/00—Measuring arrangements characterised by the use of electric or magnetic techniques
- G01B7/02—Measuring arrangements characterised by the use of electric or magnetic techniques for measuring length, width or thickness
- G01B7/023—Measuring arrangements characterised by the use of electric or magnetic techniques for measuring length, width or thickness for measuring distance between sensor and object
Abstract
A cylinder-shaped two-way capacitance displacement sensor with diametric double-window polar plate structure belongs to the technical field of precise instrument and measurement. A cylinder-shaped two-way capacitance measuring head comprises a surveying rod, a polar plate shielding part, a left polar plate, a right polar plate, a pin and a signal guide bar; the polar plate shielding part which is cylinder-shaped integrally is arranged at the end part of the surveying rod; the left polar plate and the right polar plate are diametrically arranged at the polar plate shielding part and are mutually symmetrical; clearance for insulation is arranged between the polar plates and the polar plate shielding part; a pin is arranged in the polar plate shielding part, a signal guide bar is arranged in the surveying rod, two ends of the pin are respectively connected with the left polar plate and the right polar plate and one end of the signal guide bar is connected with the pin; or two pins are arranged at the polar plate shielding part, two signal guide bars are arranged in the surveying rod, one end of each pin is respectively connected with the left polar plate and the right polar plate and the other end of each pin is respectively connected with one end of each signal guide bar. The sensor is characterized by large ratio of pit-depth to pit-diameter, capability of two-way aiming and triggering, a certain measuring range and the like.
Description
Technical field
The invention belongs to exact instrument and field of measuring technique, particularly a kind of column type reversible capacitance displacement transducer with diameter double window mouth electrode plate structure.
Background technology
After the 1950's, the breakthrough of special processing technologies such as the urgent day by day and electrosparking that high-performance, low consumption is required along with fields such as Aero-Space, super hot investment casting and servocontrol, electron beam processing, electrochemical machining, deep hole part and the little inside dimension part of other big depth-to-width ratio are widely adopted in equipments such as Aero-Space engine, motor car engine, hydraulic machinery, servo-drive system, weapon emission coefficient and exact instrument, and the characteristics of its medium-length hole part are: the aperture is generally below φ 20mm; Aspect ratio is many more than 10, and minority reaches tens even hundreds of; Very high size, shape and position accuracy demand are all arranged.The widespread use of accurate dark aperture part has proposed urgent requirement to the accurate measurement of dark orifice size, shape and location parameter, at present, on measuring, little inside dimension also remains at low levels both at home and abroad, especially measure the stage that still is in solution measurability problem at big aspect ratio and the little inside dimension of big depth-to-width ratio, and the precision measurement of dark orifice size, shape and location parameter more becomes a great difficult problem and research focus in the fields of measurement.
In the aperture and shape measure process of the big dark aperture of aspect ratio, traditional contact type measurement method is owing to the existence of ergometry, and deflection deformation can take place measuring staff, thereby introduces bigger measuring error.Accompanying drawing 1 (a) is the synoptic diagram that contact measuring head is measured measured workpiece, and wherein D is that measuring staff diameter, l are that measuring staff length, F are ergometry.Accompanying drawing 1 (b) is the synoptic diagram of measuring staff generation deflection deformation, and as seen the measuring staff axis becomes a line of deflection w (x) by straight line AB under the effect of ergometry F.If by the crooked limits of error of introducing of measuring staff is 50nm, the measuring staff elasticity modulus of materials is 200Gpa, to D=φ 3mm～φ 10mm, the maximum detection aspect ratio of contact measuring head carries out emulation when F=0.1N, 0.05N, 0.02N, simulation result as shown in Figure 2, as seen contact measuring head maximum detection aspect ratio be difficult to surpass 10: 1, its measuring accuracy with can survey aspect ratio and be severely limited, especially the little inside dimension of depth-to-width ratio and aspect ratio super large is measured occasion and more can't finish measurement.
For solving the difficult problem that the little inside dimension of big aspect ratio small aperture and other big depth-to-width ratio is measured, people turn to non-contact type measuring method to sight one after another, and emphasis is to develop contactless gauge head and the sensor that has degree of precision and can survey aspect ratio greatly.The pneumatic gauging method is a kind of more traditional non-contact type measuring method that can be used for inside diameter measurement, and its principle is to adopt nozzle baffle mechanism to realize the conversion of geometric sense to pneumatic amount, realizes measuring based on the discharge characteristic or the pressure characteristic of gauge head; For inside diameter measurement little, deep hole, often with measured hole as gaging nozzle.The shortcoming of this method is: pneumatic internal diameter gauge head belongs to contactless gauge head, but still has certain ergometry; Measuring accuracy is the highest can only to reach micron dimension, and single gauge head measurement range is very little; Have the air-flow average effect, especially with by the depth measurement aperture during as gaging nozzle, what obtain is the integrated value of orifice size and shape error, and can only be used for measuring through hole.
2000, people such as the Zhao Yong of Harbin Institute of Technology, Li Pengsheng have proposed a kind of laser fiber inside diameter measurement method (1.YongZhao et al.A novel fiber-optic sensor used for small internal curved surface measurement.Sensorand Actuators.2000, (86): 211～215; 2. Ma Huiping, Li Pengsheng, Yang Lemin. be used for the triangulation research of Fibre Optical Sensor gaging hole. measurement technology .2001, (9): 18～20; 3. Zhao Yong, Li Pengsheng, Ma Huiping, the clear nation in Pu. improve the method for laser fiber measuring system resolving power. photoelectric project .1999,26 (5): 27～30; 4. patent of invention " a kind of product surface multiparameter non-contact defocusing detect Fibre Optical Sensor ", publication number CN1160546C), this method adopts y-type optical fiber to make the contactless aiming sensor of intensity modulation type, laser feeds back out optical fiber through optical fiber input to the measured surface back reflection, determines the sighting range of gauge head to hole wall by detecting the output light intensity.This sensor construction is smaller and more exquisite, but sounding hole, blind hole and soft material workpiece, but the distance-intensity properties of sensor depends on the smooth finish and the reflective character of measured surface fully, measuring accuracy can only reach micron dimension, can't finish measurement when measured surface smooth finish and reflective character are relatively poor.
From the nineties in last century, University Of Tianjin research with capacitive transducer be used for small aperture non-contact measurement (the 1. poplar generation people. the research of blind aperture and slit three dimensional probe, 3-D probe. the doctorate paper .1993:1 of University Of Tianjin～9,42～53; 2. grandson grows storehouse, Wang Xiaobing, Liu Bin, Zheng Yizhong. the measuring method of capacitance sensing micro-aperture. and nanometer technology and precision engineering .2006,4 (2): 103～106; 3. Xu An peach, pay and respect work, Zheng Yizhong, the leaf good reputation. small deep hole internal diameter capacitance sensing Research on Measurement System. sensing technology journal .2006,19 (6): 2460～2463), the pole plate of the electric capacity gauge head of development is the cylindrical electrode that cuts out on cylindrical base, its structure as shown in Figure 3, the ideal operation position of sensor is that cylindrical plate is coaxial with measured hole, and when pole plate and measured hole disalignment and when having off-centre, what record is mean gap between cylindrical plate and measured hole; In fact often adopt relative measurement method for improving measuring accuracy, with standard component sensor is calibrated before promptly each the measurement, measure the difference in tested aperture and standard aperture.This sensor real work is in the electronic plug gauge mode, the measurement range of single gauge head is very little, measuring accuracy can only reach micron dimension, sensor does not possess following several respects characteristic: 1) gauge head has big L/D ratio 2) can carry out two-way aiming sender 3 to hole and inside dimension) can carry out the scanning survey 4 of form parameters such as flatness, circularity, cylindricity) measuring accuracy reaches the ultraprecise magnitude, is difficult to satisfy the aperture of dark aperture and the requirement of shape ultra precise measurement.
Also have some other contactless measurement and sensor to be seen in report in addition, as image method (patent of invention " microbore automatic measuring method and device ", publication number CN1493847), end face optical probe scanning method (Xu Limei, Zhang Jiayu. accurate micro hole laser measurement method. the journal .1998 of University of Electronic Science and Technology, 27 (3): 300～304) etc., be respectively to adopt image or method of optics to finish measurement, but all there is the principle defective in these methods, replace section gauge with end surface measurement, can not measure the size and shape of arbitrary section, can not satisfy the precision aperture measurement aspect practicality and the precision, the requirement of particularly big aspect ratio small aperture non-cpntact measurement.
Summary of the invention
The objective of the invention is at big aspect ratio small aperture and shape ultra precise measurement and other big dark wide little inside dimension measurement difficult problem, a kind of column type reversible capacitance sensor with diameter double window mouth electrode plate structure based on capacitance sensing mechanism is provided, to solve traditional contact type measurement method and existing non-contact type measuring method in measuring accuracy, the various defectives that the practicality aspect exists, sensor can be surveyed aspect ratio and can reach and surpass 50: 1, aiming resolution reaches nanometer scale, and the precision measurement and other the big dark wide little inside dimension that can be used for above dark small aperture of diameter phi 3mm and shape are measured occasion.
Technical solution of the present invention is:
A kind of column type reversible capacitance displacement transducer with diameter double window mouth electrode plate structure, comprise electric capacity gauge head and conversion of signals and treatment circuit, this electric capacity gauge head is a column type reversible capacitance gauge head structure, and cylindrical reversible capacitance gauge head is made up of measuring staff, pole plate shielding part, left pole plate, right pole plate, pin, signal guide rod; Whole cylindrical pole plate shielding part is installed on the measuring staff end, and left pole plate and right pole plate diameter are arranged on the pole plate shielding part, and two-plate is symmetrical, is provided with clearance for insulation between left pole plate and right pole plate and pole plate shielding part; Equipped pin in the pole plate shielding part, equipped signal guide rod in measuring staff, the two ends of pin are connected with right pole plate with left pole plate respectively, and an end of signal guide rod is connected with pin; Perhaps equipped two pins in the pole plate shielding part are equipped with two signal guide rods in measuring staff, and two pins end separately is connected with right pole plate with left pole plate respectively, and the other end of two pins is connected with two signal guide rods end separately respectively.
Heterodyne frequency modulation type conversion of signals and treatment circuit that described conversion of signals and treatment circuit are made up of the signal generator that preceding shakes, local oscillation signal generator, mixing unit, intermediate-frequency filter, signal shift switch, signal reshape unit, frequency discrimination unit, microprocessor, display unit and computer interface; Wherein, column type reversible capacitance gauge head is connected with the signal generator that before shakes, before the signal generator that shakes be connected with mixing unit, intermediate-frequency filter, signal shift switch, signal reshape unit, frequency discrimination unit, microprocessor successively, before the signal generator that shakes directly be connected again with signal shift switch, the local oscillation signal generator is connected with the mixing unit, and microprocessor includes display unit and computer interface.
Described left pole plate and right pole plate are shaped as square or rectangle or oval or circular.
In the chamber of described measuring staff and pole plate shielding part, be provided with keeper.
Described measuring staff, pole plate shielding part, left pole plate, right pole plate, pin and signal guide rod are good conductor.
Described measuring staff, pole plate shielding part, left pole plate and right pole plate are that metal-coated membrane constitutes on insulating material.
Described keeper is to be made by epoxide resin material.
The width of the clearance for insulation between described left pole plate and right pole plate and the pole plate shielding part is 20 μ m～200 μ m.
The signal generator that shakes before described adopts a carat bold and vigorous oscillatory circuit, and is installed in the metallic shield box.
The invention provides a kind of column type reversible capacitance displacement transducer with diameter double window mouth electrode plate structure, two cylinder window-shaped pole plates are symmetrically distributed on the pole plate shielding part diameter direction of electric capacity gauge head of the present invention, when two ends, tested aperture are aimed at measured piece, sensor has the sensing characteristics of symmetry, triggers ability thereby have two-way aiming; When carrying out inside diameter measurement, recorded the aiming gap of both sides and provided trigger pip by sensor, by the displacement that other grand dimensional measurement sensor records gauge head between twice triggering, measured bore directly equals both sides aiming gap, gauge head diameter and gauge head displacement sum; Sensor both can be used for the trigger-type aiming in the dimensional measurement, can be used for the high-acruracy survey of form parameters such as circularity, cylindricity again.
Technological innovation of the present invention and the good result that has are as follows:
(1) the present invention is directed to the difficult problem that the little inside dimension of big aspect ratio small aperture and other big depth-to-width ratio is measured, a kind of contactless method for sensing that can survey aspect ratio greatly that has is provided, its principle is the space three-dimensional aiming electric field that forms by gauge head pole plate and measured piece, gauge head is from radially carrying out the contactless aiming of high precision to measured piece, sensor has concurrently and triggers and the micrometer dual-use function, its maximum detection aspect ratio can reach and surpass 50: 1, be higher than any existing method and technology, can solve traditional contact type measurement method ergometry and cause the measuring staff deflection and survey the end distortion, can survey the problem that aspect ratio and measuring accuracy are severely limited.
(2) the present invention proposes a kind of reversible capacitance aiming gauge head with diameter bicylindrical window electrode plate structure, diameter on the cylindrical plate shielding part, two cylinder window-shaped pole plates are symmetrically distributed, pole plate and gauge head structural design by symmetry, gauge head has symmetrical sensing characteristics when at measured hole diameter two ends measured piece being aimed at, thereby have two-way aiming and trigger ability, sensor has certain range, its displacement resolving power can reach nanometer scale, both can be used for the precision measurement of big aspect ratio small aperture and the little inside dimension of other big depth-to-width ratio, can be used for inner structure again, the high-acruracy survey of inner chamber body form parameter.
(3) the invention provides a kind of digital heterodyne FM signal conversion and treatment technology, the local oscillation signal generator adopts the Direct Digital synthesis mode to constitute, the frequency discrimination unit adopts synchronous frequency measurement technology of multicycle, avoided traditional analog formula circuit because the components and parts temperature is floated, signal amplitude and deficiency such as frequency stability is poor, harmonic distortion is big in the aging zero point drift of introducing and analog-modulated and the demodulation, can obviously improve the precision level of sensor, enable to satisfy the requirement of precision aperture measurement, especially big aspect ratio small aperture non-cpntact measurement.
Description of drawings
The synoptic diagram that Fig. 1 (a) measures measured workpiece for contact measuring head (b) is the synoptic diagram of measuring staff generation deflection deformation;
Fig. 2 is the simulation result of contact measuring head maximum detection aspect ratio;
Fig. 3 is the structural representation of the electric capacity gaging hole transducer probe assembly of University Of Tianjin's development;
Fig. 4 is the column type reversible capacitance displacement transducer synoptic diagram with diameter double window mouth electrode plate structure of the present invention;
Fig. 5 is the front elevation of column type reversible capacitance gauge head embodiment 1 of the present invention, the synoptic diagram of promptly single pin, mono signal guide rod structure;
Fig. 6 is the side view of Fig. 5;
Fig. 7 be among Fig. 6 A-A to cut-open view;
Fig. 8 is the cut-open view of column type reversible capacitance gauge head embodiment 2 of the present invention, i.e. the synoptic diagram of double-pin nail and dual signal guide rod structure;
Fig. 9 is the front elevation of reversible capacitance gauge head embodiment 3 of the present invention;
Figure 10 is the side view of Fig. 9;
Figure 11 is the synoptic diagram that column type reversible capacitance gauge head and measured workpiece aim in a side.
Among the figure, 1 dead ring; 2 protection rings; 3 insulators; 4 apertures; 5 potential electrode; 6 protection rings; 7 dead rings; the end of 8 gauge heads; 9 hollow cylinders; the lead of 10 potential electrode; the end of 11 gauge heads; 12 column type reversible capacitance gauge heads; 13 conversion of signals and treatment circuit; signal generator shakes before 14; 15 local oscillation signal generators; 16 mixing unit; 17 intermediate-frequency filters; 18 signal shift switch; 19 signal reshape unit; 20 frequency discrimination unit; 21 microprocessors; 22 display units; 23 computer interfaces; 24 signal guide rods; 25 measuring staffs; 26 pole plate shielding parts; 27 left pole plates; 28 right pole plates; 29 pins; 30 clearance for insulations; 31 keepers; 32 measured pieces; 33 the earth.
Embodiment
Below in conjunction with accompanying drawing the specific embodiment of the present invention is elaborated, and provides embodiment.
A kind of column type reversible capacitance displacement transducer with diameter double window mouth electrode plate structure, comprise electric capacity gauge head 12 and conversion of signals and treatment circuit 13, it is characterized in that: this electric capacity gauge head 12 is column type reversible capacitance gauge head structure, and cylindrical reversible capacitance gauge head 12 is made up of measuring staff 25, pole plate shielding part 26, left pole plate 27, right pole plate 28, pin 29, signal guide rod 24; Whole cylindrical pole plate shielding part 26 is installed on measuring staff 25 ends, and left pole plate 27 and right pole plate 28 diameters are arranged on the pole plate shielding part 26, and two-plate is symmetrical, is provided with clearance for insulation 30 between left pole plate 27 and right pole plate 28 and pole plate shielding part 26; Equipped pin 29 in pole plate shielding part 26, equipped signal guide rod 24 in measuring staff 25, the two ends of pin 29 are connected with right pole plate 28 with left pole plate 27 respectively, and an end of signal guide rod 24 is connected with pin 29; Perhaps in pole plate shielding part 26, be equipped with two pins 29, equipped two signal guide rods 24 in measuring staff 25, two pins (29) end separately is connected with right pole plate 28 with left pole plate 27 respectively, and the other end of two pins (29) is connected with two signal guide rods (24) end separately respectively.The present invention is that gauge head is from radially carrying out contactless aiming to measured piece by the space three-dimensional aiming electric field that forms between pole plate and measured piece, and the maximum detection length-diameter ratio can reach and surpass 50: 1; Left side pole plate, right pole plate are when measured size two ends aiming measured piece, and sensor has symmetrical sensing characteristics, triggers ability thereby have two-way aiming; When sensor carries out the inside dimension measurement, record the aiming gap of both sides and provide trigger pip by sensor, by the displacement that other grand dimensional measurement sensor records gauge head between twice triggering, then tested inside dimension equals both sides aiming gap, gauge head diameter and gauge head displacement sum; Sensor has certain range, both can be used for the trigger-type aiming in the dimensional measurement, can be used for the high-acruracy survey of form parameters such as circularity, cylindricity again.
Heterodyne frequency modulation type conversion of signals and treatment circuit that described conversion of signals and treatment circuit 13 are made up of the signal generator 14 that preceding shakes, local oscillation signal generator 15, mixing unit 16, intermediate-frequency filter 17, signal shift switch 18, signal reshape unit 19, frequency discrimination unit 20, microprocessor 21, display unit 22 and computer interface 23; Wherein, column type reversible capacitance gauge head 12 is connected with the signal generator 14 that before shakes, before the signal generator 14 that shakes be connected with mixing unit 16, intermediate-frequency filter 17, signal shift switch 18, signal reshape unit 19, frequency discrimination unit 20, microprocessor 21 successively, before the signal generator 14 that shakes directly be connected again with signal shift switch 18, local oscillation signal generator 15 is connected with mixing unit 16, and microprocessor 21 includes display unit 22 and computer interface 23.The measured position shifting signal produces frequency modulation (PFM) to the high-frequency carrier signal that the signal generator that preceding shakes produces, and the local oscillation signal that FM signal and local oscillation signal generator produce carries out mixing, intermediate-freuqncy signal is carried out frequency discrimination handle, and therefrom demodulates the information of tested displacement.
Described left pole plate 27 and right pole plate 28 are shaped as square or rectangle or oval or circular.
In the chamber of described measuring staff 25 and pole plate shielding part 26, be provided with keeper 31.
Described measuring staff 25, pole plate shielding part 26, left pole plate 27, right pole plate 28, pin 29 and signal guide rod 24 are good conductor.
Described measuring staff 25, pole plate shielding part 26, left pole plate 27 and right pole plate 28 are that metal-coated membrane constitutes on insulating material.
Described keeper 31 is to be made by epoxide resin material.
The width of the clearance for insulation 30 between described left pole plate 27 and right pole plate 28 and the pole plate shielding part 26 is 20 μ m～200 μ m.
The signal generator 14 that shakes before described adopts a carat bold and vigorous oscillatory circuit, and is installed in the metallic shield box.
Described local oscillation signal generator 15 can adopt Direct Digital frequency synthesis mode to obtain, to obtain the local oscillation signal of high-amplitude, frequency stability; Described frequency discrimination unit 20 can adopt synchronous frequency measurement mode of multicycle to constitute, to carry out the high accuracy number frequency measurement.
Below in conjunction with an embodiment structure of the present invention and principle of work are described in detail:
Accompanying drawing 4 has provided the synoptic diagram with column type reversible capacitance displacement transducer of diameter double window mouth electrode plate structure of the present invention, accompanying drawing 11 is reversible capacitance gauge head and measured workpiece schematic cross-sections in the side aiming of measured diameter, in the present embodiment, the diameter on the face of cylinder, pole plate place is φ 2.5mm, and the measured workpiece aperture is φ 3mm～φ 20mm.Measured workpiece ground connection is as a pole plate, and a pole plate of gauge head aims at it, and the two forms an aiming capacitance field, and the aiming gap is 20 μ m～100 μ m.Because the aiming gap between pole plate and measured workpiece is very little with respect to the gauge head size, think that line of electric force is all perpendicular to pole plate so can be similar to, then each infinitesimal electric capacity of pole plate and measured workpiece formation all can be regarded a capacity plate antenna as, and the appearance value of each infinitesimal electric capacity is:
Center of circle O with pole plate xsect place circle
2For initial point, direction of measurement are set up rectangular coordinate system xO for the x axle
2Y.The parallel axes and the vertical pole plate xsect of dividing equally of x axle of the face of cylinder, pole plate place axis and measured workpiece during aiming.If the measured hole radius is R, the face of cylinder, pole plate place radius is r, and the pole plate height is l, and the aiming gap is δ
x, as shown in Figure 11.
With the initial point is starting point, gets arbitrarily angled θ and makes ray and meet at an A and B with measured hole cross section circle and pole plate respectively, and geometric relationship has from figure | O
1A|=R, | O
1O
2|=R-r-δ
xIf | AB|=δ, then | O
2A|=r+ δ makes L=r+ δ
x, according to the cosine law at triangle O
1O
2Have among the A:
R
2＝(R-L)
2+(r+δ)
2+2cosθ·(R-L)(r+δ) (2)
Put in order:
If pole plate xsect institute is 2 ξ to central angle, then the θ interval is [ξ, ζ], all infinitesimals is quadratured can aim at electric capacity and be:
The aiming electric capacity that formula (3) substitution following formula is got under the desirable aiming state is:
The value of present embodiment aiming electric capacity is about 1pF.
In the present embodiment, before the signal generator 14 that shakes are high stability Colpitts oscillation circuits, constitute, and be installed in the metallic shield box by high stability wire-wound inductance, mica capacitor, CBB electric capacity, the little components and parts of high stability triode equitemperature coefficient.The high_frequency sine wave that produces a frequency and amplitude stability is as carrier signal, and its frequency is 4MHz, and amplitude is 1Vpp.Measuring staff reliably is connected to realize the shielding fully to signal with shielding box, can effectively reduce the interference of external electromagnetic field.When reversible capacitance gauge head and measured piece generation relative displacement, the aiming electric capacity changes, and the signal change of resonance frequency of shaking before correspondingly can causing realizes the frequency modulation (PFM) of measured position shifting signal to carrier signal.Before the signal f that shakes
sExpression formula be:
In the formula: C
s---aiming electric capacity;
C
o---equivalent stray capacitance in the preceding signal generator circuit that shakes.
Local oscillation signal generator 15 can adopt canonical function signal generator (Agilent33120A), or adopts microprocessor (MSP430F149) control Direct Digital frequency synthesis chip (AD9953) to obtain.Mixing unit 16 is that core constitutes local oscillation signal f with mixer chip (MC1496)
lWith the signal f that preceding shakes
sAfter mixing, obtain one group and frequently, difference frequency signal f
i:
f
i＝|±nf
s±mf
l| n、m＝1，2，3... (7)
Intermediate-frequency filter 17 is made of the ceramic filter of centre frequency 455kHz, mixing element output signal f
iAfter intermediate-frequency filter filtering, obtain the intermediate-freuqncy signal f that centre frequency is 455kHz
m:
f
m＝|f
s-f
l| (8)
Accompanying drawing 5～accompanying drawing 10 has provided 3 embodiment of reversible capacitance gauge head of the present invention.In these 3 embodiment, measuring staff 25 adopts the thin-wall steel tube that satisfies the linearity requirement, and diameter is φ 2.5mm, the about 100 μ m of wall thickness.Pole plate shielding part 26 adopts the little beryllium-bronze material of temperature coefficient to process through turning simultaneously as the matrix of pole plate processing, and its external diameter is φ 3mm, the about 200 μ m of wall thickness, and measuring staff 25 adopts the wringing fit mode to be connected with pole plate shielding part 26.Adopt machining process to process the window-shaped pole plate 27 and 28 that two diameters distribute on the pole plate shielding part 26, pole plate and pole plate shielding part reliably insulate, and clearance for insulation 30 width are 20 μ m～30 μ m, and width is even.Infusion epoxy resins and make it to solidify and form mechanical positioning that keeper 31 realizes each parts of gauge head and be connected in measuring staff 25 and the pole plate shielding part 26.
Accompanying drawing 5 is the front elevation of the embodiment 1 of column type reversible capacitance gauge head, Fig. 6 is the left view of Fig. 5, Fig. 7 is the cut-open view along A-A direction among Fig. 6, in embodiment 1, left side pole plate 27 is a rectangle with right pole plate 28, diameter distributes and symmetrically, links to each other with a signal guide rod 24 by a pin 29, reliably insulate by clearance for insulation 30 and pole plate shielding part 26.Infusion epoxy resin and make it to solidify formation positioning element 31 in measuring staff 25 and pole plate shielding part 26.
Fig. 8 is the cut-open view of reversible capacitance gauge head embodiment 2 of the present invention, in embodiment 2, the window-shaped pole plate is a rectangle, and left pole plate 27 links to each other with left and right sides two parts of signal guide rod 24 by left and right sides two parts of pin 29 respectively with right pole plate 28, and left and right sides two parts of signal guide rod reliably insulate.
Fig. 9 is the front elevation of reversible capacitance gauge head embodiment 3 of the present invention, Figure 10 is the left view of Fig. 9, in embodiment 3, left side pole plate 27 is oval with right pole plate 28, diameter distributes and is symmetrical, link to each other with a signal guide rod 24 by a pin 29, reliably insulate by clearance for insulation 30 and pole plate shielding part 26.
Gauge head when work, measuring staff 25 and pole plate shielding part 26 ground connection on electric because pole plate 27 and 28 with pole plate shielding part 26 equipotential not, so can produce stray capacitance.Can adopt the driving cable technology, make measuring staff 25, pole plate shielding part 26 on current potential, realize following to left pole plate 27 and right pole plate 28 current potentials, can reach the purpose of eliminating stray capacitance and edge effect, overlap the thin-wall metal bar that one deck plays shielding action again in the measuring staff outside, and on electric ground connection.
Claims (9)
1. column type reversible capacitance displacement transducer with diameter double window mouth electrode plate structure, comprise electric capacity gauge head (12) and conversion of signals and treatment circuit (13), it is characterized in that: this electric capacity gauge head (12) is column type reversible capacitance gauge head structure, and cylindrical reversible capacitance gauge head (12) is made up of measuring staff (25), pole plate shielding part (26), left pole plate (27), right pole plate (28), pin (29), signal guide rod (24); Whole cylindrical pole plate shielding part (26) is installed on measuring staff (25) end, left side pole plate (27) and right pole plate (28) diameter are arranged on the pole plate shielding part (26), two-plate is symmetrical, is provided with clearance for insulation (30) between left pole plate (27) and right pole plate (28) and pole plate shielding part (26); An equipped pin (29) in pole plate shielding part (26), an equipped signal guide rod (24) in measuring staff (25), the two ends of pin (29) are connected with right pole plate (28) with left pole plate (27) respectively, and an end of signal guide rod (24) is connected with pin (29).
2. the column type reversible capacitance displacement transducer with diameter double window mouth electrode plate structure according to claim 1 is characterized in that heterodyne frequency modulation type conversion of signals and treatment circuit that described conversion of signals and treatment circuit (13) are made up of the signal generator that preceding shakes (14), local oscillation signal generator (15), mixing unit (16), intermediate-frequency filter (17), signal shift switch (18), signal reshape unit (19), frequency discrimination unit (20), microprocessor (21), display unit (22) and computer interface (23); Wherein column type reversible capacitance gauge head (12) is connected with the signal generator that before shakes (14), before the signal generator (14) that shakes be connected with mixing unit (16), intermediate-frequency filter (17), signal shift switch (18), signal reshape unit (19), frequency discrimination unit (20), microprocessor (21) successively, before the signal generator (14) that shakes directly be connected again with signal shift switch (18), local oscillation signal generator (15) is connected with mixing unit (16), and microprocessor (21) includes display unit (22) and computer interface (23).
3. the column type reversible capacitance displacement transducer with diameter double window mouth electrode plate structure according to claim 1 is characterized in that described left pole plate (27) and right pole plate (28) are shaped as square or rectangle or oval or circular.
4. the column type reversible capacitance displacement transducer with diameter double window mouth electrode plate structure according to claim 1 is characterized in that being provided with keeper (31) in the chamber of described measuring staff (25) and pole plate shielding part (26).
5. the column type reversible capacitance displacement transducer with diameter double window mouth electrode plate structure according to claim 1 is characterized in that described measuring staff (25), pole plate shielding part (26), left pole plate (27), right pole plate (28), pin (29) and signal guide rod (24) are good conductor.
6. the column type reversible capacitance displacement transducer with diameter double window mouth electrode plate structure according to claim 1 is characterized in that described measuring staff (25), pole plate shielding part (26), left pole plate (27) and right pole plate (28) are that metal-coated membrane constitutes on insulating material.
7. the column type reversible capacitance displacement transducer with diameter double window mouth electrode plate structure according to claim 4 is characterized in that described keeper (31) is to be made by epoxide resin material.
8. the column type reversible capacitance displacement transducer with diameter double window mouth electrode plate structure according to claim 1, the width that it is characterized in that the clearance for insulation (30) between described left pole plate (27) and right pole plate (28) and the pole plate shielding part (26) are 20 μ m～200 μ m.
9. the column type reversible capacitance displacement transducer with diameter double window mouth electrode plate structure according to claim 2, the signal generator (14) that it is characterized in that shaking before described adopts a carat bold and vigorous oscillatory circuit, and is installed in the metallic shield box.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2009100713050A CN101493310B (en) | 2009-01-21 | 2009-01-21 | Cylinder type bidirectional capacitance displacement sensor with across double-window counter electrode structure |
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| Application Number | Priority Date | Filing Date | Title |
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| CN2009100713050A CN101493310B (en) | 2009-01-21 | 2009-01-21 | Cylinder type bidirectional capacitance displacement sensor with across double-window counter electrode structure |
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| CN101493310A CN101493310A (en) | 2009-07-29 |
| CN101493310B true CN101493310B (en) | 2010-11-10 |
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| CN101957165B (en) * | 2010-09-29 | 2012-05-09 | 天津大学 | Measuring apparatus for internal diameter of small deep hole |
| CN102359754A (en) * | 2011-08-09 | 2012-02-22 | 张华建 | Differential-capacitive length sensor |
| CN102636104B (en) * | 2012-05-15 | 2013-12-11 | 安徽工业大学 | Capacitive threaded steel wire diameter on-line measurement system |
| CN104654993B (en) * | 2015-01-14 | 2017-08-11 | 中国计量科学研究院 | A kind of differential capacitance type one-dimensional position vector sensor |
| JP6718622B2 (en) | 2017-05-26 | 2020-07-08 | 株式会社京岡 | Gap sensor and gap measuring method |
| CN110993036B (en) * | 2019-11-27 | 2023-06-06 | 东华大学 | Method for determining distance between needles of multi-needle nano-structure active water ion generator |
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