CN1330945C - Material level sensor in radio frequency medium measure type - Google Patents

Material level sensor in radio frequency medium measure type Download PDF

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Publication number
CN1330945C
CN1330945C CNB2005100463803A CN200510046380A CN1330945C CN 1330945 C CN1330945 C CN 1330945C CN B2005100463803 A CNB2005100463803 A CN B2005100463803A CN 200510046380 A CN200510046380 A CN 200510046380A CN 1330945 C CN1330945 C CN 1330945C
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rapier
material level
input end
output terminal
comparer
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CNB2005100463803A
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CN1687717A (en
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刘国桐
马文海
李红军
徐文杰
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刘国桐
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Abstract

The present invention relates to a material level sensor in a radio frequency medium measure type, which comprises a free running oscillator, wherein an output end of the free running oscillator is connected to one pole of a sensor probe through a shielded conductor, and the other pole of the sensor probe is connected to an input end of a voltage amplifier through a shielded conductor; an output end of the voltage amplifier is connected to a voltage follower through detection, an output end of the voltage follower is split into two roads, wherein one road is connected with a fault comparator through a resistor, an output end of the fault comparator is connected with an indication circuit of an operating state, the other road is connected with a threshold comparator through a resistor, an output end of the threshold comparator is connected with an executive circuit or connected to an input end of an analog display unit through a calibration adjustment resistor, and an output end of the analog display unit is provided with an executive circuit. The present invention has the advantage that a measuring mode is directly obtained through simple circuit structure, so that a measuring characteristic is close to linearity, and measurement range is enlarged; use is easy, and the present invention is convenient for installation; the sensor which operatively forms a unique system has a display function of fault diagnosis and is convenient for perambulation inspection.

Description

Material level sensor in radio frequency medium measure type
Technical field
The invention belongs to a kind of electronic sensor apparatus, particularly a kind of material level sensor in radio frequency medium measure type.
Background technology
The electronic type level sensor is widely used in field of industrial automatic control, and existing electronic type level sensor is divided into radar type level sensor, ultrasonic type level sensor, capacitive material level transducer and radio frequency admittance formula level sensor.Radar type level sensor and ultrasonic type level sensor convert the tested material position signalling to by the reflection on testee (material) the surface ripple that turns back, and all belong to non-cpntact measurement.Above-mentioned radar type level sensor and ultrasonic type level sensor circuit structure more complicated, there is detection blind area in the cost height, and when particularly the radar type level sensor was measured the level of filler material of band dust-like, effect was undesirable; The ultrasonic type level sensor is not suitable for pressure vessel, is usually used in measuring the liquid material level.
The principle of work of capacitive material level transducer and radio frequency admittance formula level sensor is that the rapier of sensor and chamber wall equivalence are two utmost points of capacitor, and material is considered as the medium between them.Material change in location in the container is equivalent to the variation of electric capacity, and this variable quantity is converted to the output of analog quantity (switch) signal.Radio frequency admittance formula level sensor has increased a screen layer in the rapier parts, mutually insulated between it and rapier and the sheath, and be provided with identical radiofrequency signal, making between rapier and the screen layer does not have capacity current, form to isolate between rapier and the chamber wall, in case on rapier buildup.
Capacitive material level transducer and radio frequency admittance formula level sensor, the characteristic of its measurement is non-linear, measurement range is narrow.Because between the main frame of sensor and the rapier is capacitive circuit, because of the existence of its natural capacity and distributed capacitance, is subjected to electromagnetic interference effect big, be connected lead between rapier parts and the main frame, unsuitable long.It is strict over the ground, can not establish one's own system in its place of working, needs to be ground (when container is nonmetallic materials, an auxiliary electrode need be set also) by chamber wall.When installing and using, be mechanical attachment between rapier parts and the container, but not be electrically connected.Contact resistance can produce variate along with the time, and the reference point that causes measuring departs from, and sensor loses accuracy.Under high temperature, low temperature, wet environment condition, the component materials of rapier and insulating medium in the lead and material also all along with temperature changes, cause the parameter change in the circuit, though be provided with compensating circuit in sensor, compensation effect is undesirable.When two or many sensors are installed in a container, occur interfering with each other.
Summary of the invention
The objective of the invention is to overcome the problems referred to above that existing level sensor exists, a kind of circuit structure advantages of simple is provided, media variations is directly become analog quantity or switching signal output, make the characteristic of measurement approach linearity, enlarged range ability; Easy to use, be not subjected to the long restriction of rapier lead-in wire; Working sensor ground establishes one's own system, and need not to connect in addition auxiliary ground, both has been applicable to point measurement, can be used for continuous coverage again; Have the fault diagnosis Presentation Function, made things convenient for walkaround inspection; Accuracy, stability and the reliability of this working sensor have been improved.
Technical solution of the present invention is: it has a self-excited oscillator that is used to produce electric signal, its special character is the output terminal of self-excited oscillator is connected to sensor probe by shielded conductor a rapier, another rapier of sensor probe is connected to the input end of voltage amplifier by shielded conductor, the output terminal of voltage amplifier is connected to the input end of detection and wave filter, by detection and wave filter the voltage signal that amplifies is become d. c. voltage signal, the output terminal of detection filter is connected to the input end of voltage follower, the output terminal of voltage follower is divided into two-way, wherein the first via connects the input end of fault comparer through isolation resistance, the output terminal of fault comparer connects the duty indicating circuit, the second tunnel input end by isolation resistance connection threshold value comparer, the output terminal of threshold value comparer connects the executive circuit or the second tunnel that is used for control material level when point measurement and adjusts the input end that resistance is connected to the analog quantity display unit that is used for the continuous coverage material level and shows measurement result by calibration, be connected to the executive circuit that is used in continuous coverage time control material level at analog quantity display unit output terminal.
Above-mentioned material level sensor in radio frequency medium measure type, said self-excited oscillator, voltage amplifier, detection and wave filter, voltage follower, isolation resistance, fault comparer, threshold value comparer and executive circuit or self-excited oscillator, voltage amplifier, detection and wave filter, voltage follower, isolation resistance, fault comparer, analog quantity display unit and executive circuit are integrated into an integrated circuit.
Above-mentioned material level sensor in radio frequency medium measure type, said sensor probe be by bolt or ring flange, be located at bolt or ring flange upper surface two rapier stationary pipes, be located at bolt or ring flange bottom socket, be installed in rapier stationary pipes top insulator, be installed in the rapier on the insulator, the lead that is connected between rapier and the socket constitutes.
Above-mentioned material level sensor in radio frequency medium measure type is provided with the insulating medium body between rapier stationary pipes and rapier, in case the granular material jam.
Advantage of the present invention is the principle of work mode with condenser type and radio frequency admittance formula level sensor: " media variations-electric capacitance change-become analog quantity (switch) signal to export." abbreviation is: " media variations-become analog quantity (switch) signal output.", all have the principle of its corresponding specific inductive capacity according to any material, realized with simple circuit configuration, directly obtain the mode of measurement, make the characteristic of measurement approach linearity, enlarged range ability; The rapier lead-in wire is compared with radio frequency admittance formula level sensor with condenser type and can be prolonged more than hundred times, and this material level sensor in radio frequency medium measure type circuit structure is simple, easy to use, is convenient to install; Working sensor ground establishes one's own system, and need not to connect in addition auxiliary ground; Both be applicable to point measurement, and can be used for continuous coverage again; Have the fault diagnosis Presentation Function, made things convenient for walkaround inspection; Accuracy, stability and the reliability of this working sensor have been improved.
The drawing explanation:
Fig. 1 is circuit block diagram of the present invention (corresponding embodiment 1);
Fig. 2 is the structural representation of sensor probe among the present invention;
Fig. 3 is the vertical view of Fig. 2;
Fig. 4 is circuit block diagram of the present invention (corresponding embodiment 2).
Embodiment
Embodiment 1:
As Fig. 1~shown in Figure 3, the present invention has a self-excited oscillator 1 (present embodiment self-excited oscillator 1 is used to produce pulse signal) that is used for producing electric signal, the output terminal of self-excited oscillator 1 is connected to a rapier of bipolar sensor probe 2 by shielded conductor 11, said sensor probe 2 is by bolt (or ring flange) 205, be located at two rapier stationary pipes 203 of bolt (or ring flange) 205 upper surfaces, be located at the socket 206 of bolt (or ring flange) 205 bottoms, be installed in the insulator 202 at rapier stationary pipes 203 tops, be installed in the rapier 201 on the insulator 202, the lead 204 that is connected between rapier 201 and the socket 206 constitutes, when being used for the granular material measurement, between rapier stationary pipes 203 and rapier 201, be provided with insulating medium body 207, to prevent the granular material jam.Another rapier of sensor probe 2 is connected to the input end of voltage amplifier 3 by shielded conductor 12, the output terminal of voltage amplifier 3 is connected to the input end of detection and wave filter 4, said voltage amplifier is the pulse voltage amplifier, so that its amplification effect is better.By detection and wave filter 4 voltage signal that amplifies is become d. c. voltage signal, the output terminal of detection filter 4 is connected to the input end of voltage follower 5, the output terminal of voltage follower 5 is divided into two-way, wherein the first via connects the input end of fault comparer 6 through isolation resistance R2, the output terminal of fault comparer 6 connects duty indicating circuit 7, and said duty indicating circuit 7 can be made of current-limiting resistance and luminotron; The second tunnel input end by isolation resistance R1 connection threshold value comparer 8, the output terminal of threshold value comparer 8 connects the executive circuit 9 that is used for control material level when point measurement.Said self-excited oscillator 1, voltage amplifier 3, detection and wave filter 4, voltage follower 5, isolation resistance R1 and R2, fault comparer 6, threshold value comparer 8 and executive circuit 9 are integrated into an integrated circuit.
Meet direct supply V during this working sensor CCNormal operation of sensor, in the container during no material, the pulse signal of self-excited oscillator 1 is by the coupling between the rapier 2, be transferred to the input end of voltage amplifier 3, this signal is through amplifying and detection, after the filtering, become d. c. voltage signal, this signal is again by the input end of voltage follower 5 to fault comparer 6, when normal operation of sensor, d. c. voltage signal by voltage follower 5 output is greater than the reference voltage preset value of fault comparer 6, working indicating 7 luminous indications, expression has working power voltage, and from self-excited oscillator 1 to voltage follower 5 and fault comparer 6 each circuit inside and unit, damage without any electronic devices and components, and working properly.Otherwise, the not luminous indication of working indicating 7, the expression sensor is in malfunction or does not have working power voltage.
Normal operation of sensor, when in the container material being arranged, the pulse signal of self-excited oscillator 1 is transferred to voltage amplifier 3 by the material between the sensor rapier, behind this signal process amplification, detection, the worry ripple, becomes d. c. voltage signal.This signal is again through the input end of voltage follower 5 to threshold value comparer 8, and the reference voltage that threshold value comparer 8 is provided with is decided according to the character of on-site actual situations and material.When material reached sensor rapier installation site, the d. c. voltage signal of process voltage follower 5 outputs was greater than the reference voltage of threshold value comparer 8, and the output state of threshold value comparer 8 changes, and control signal is carried out in output, thereby finishes the control of material level.
Embodiment 2:
As Fig. 2, Fig. 3 and shown in Figure 4, the present invention has a self-excited oscillator 1 that is used to produce electric signal, the output terminal of self-excited oscillator 1 is connected to a rapier of bipolar sensor probe 2 by shielded conductor 11, said sensor probe 2 is by bolt (or ring flange) 205, be located at two rapier stationary pipes 203 of bolt (or ring flange) 205 upper surfaces, be located at the socket 206 of bolt (or ring flange) 205 bottoms, be installed in the insulator 202 at rapier stationary pipes 203 tops, be installed in the rapier 201 on the insulator 202, the lead 204 that is connected between rapier 201 and the socket 206 constitutes, when being used for the granular material measurement, between rapier stationary pipes 203 and rapier 201, be provided with insulating medium body 207, to prevent the granular material jam.Another rapier of sensor probe 2 is connected to the input end of voltage amplifier 3 by shielded conductor 12, the output terminal of voltage amplifier 3 is connected to the input end of detection and wave filter 4, said voltage amplifier is the pulse voltage amplifier, so that its amplification effect is better.By detection and wave filter 4 voltage signal that amplifies is become d. c. voltage signal, the output terminal of detection filter 4 is connected to the input end of voltage follower 5, the output terminal of voltage follower 5 is divided into two-way, wherein the first via is through the input end of isolation resistance R2 connection fault comparer 6, and the output terminal of fault comparer 6 connects duty indicating circuit 7; The second the tunnel adjusts resistance R 3 by calibration is connected to analog quantity display unit 10 input ends, is used for the continuous coverage material level and shows measurement result, is connected to executive circuit 13 at the output terminal of analog quantity display unit 10, is used for control material level when continuous coverage.Said self-excited oscillator 1, voltage amplifier 3, detection and wave filter 4, voltage follower 5, isolation resistance R2, fault comparer 6, analog quantity display unit 10 and executive circuit 13 can be integrated into an integrated circuit.

Claims (4)

1, a kind of material level sensor in radio frequency medium measure type, comprise the self-excited oscillator (1) that is used to produce electric signal, it is characterized in that, the output terminal of self-excited oscillator (1) is connected to a rapier of bipolar sensor probe (2) by shielded conductor (11), another rapier of sensor probe (2) is connected to the input end of voltage amplifier (3) by shielded conductor (12), the output terminal of voltage amplifier (3) is connected to the input end of detection and wave filter (4), by detection and wave filter (4) voltage signal that amplifies is become d. c. voltage signal, the output terminal of detection filter (4) is connected to the input end of voltage follower (5), the output terminal of voltage follower (5) is divided into two-way, wherein the first via connects the input end of fault comparer (6) through isolation resistance (R2), the output terminal of fault comparer (6) connects duty indicating circuit (7), the second tunnel input end by isolation resistance (R1) connection threshold value comparer (8), the output terminal of threshold value comparer (8) connects the executive circuit (9) or the second tunnel that is used for control material level when point measurement and is connected to analog quantity display unit (10) input end that is used for the continuous coverage material level and shows measurement result by calibration adjustment resistance (R3), the executive circuit (13) that when analog quantity display unit (10) output terminal is connected in continuous coverage, is used to control material level.
2, material level sensor in radio frequency medium measure type according to claim 1 is characterized in that: said self-excited oscillator (1), voltage amplifier (3), detection and wave filter (4), voltage follower (5), isolation resistance (R1 and R2), fault comparer (6), threshold value comparer (8) and executive circuit (9) or self-excited oscillator (1), voltage amplifier (3), detection and wave filter (4), voltage follower (5), isolation resistance (R2), fault comparer (6), analog quantity display unit (10) and executive circuit (13) are integrated into an integrated circuit.
3, material level sensor in radio frequency medium measure type according to claim 1 is characterized in that: said sensor probe (2) be by bolt or ring flange (205), be located at bolt or ring flange (205) upper surface two rapier stationary pipes (203), be located at bolt or ring flange (205) bottom socket (206), be installed in rapier stationary pipes (203) top insulator (202), be installed in rapier (201) on the insulator (202), be connected lead (204) formation between rapier (201) and the socket (206).
4, material level sensor in radio frequency medium measure type according to claim 3 is characterized in that: be provided with insulating medium body (207) between rapier stationary pipes (203) and rapier (201).
CNB2005100463803A 2005-04-30 2005-04-30 Material level sensor in radio frequency medium measure type Expired - Fee Related CN1330945C (en)

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Publication number Priority date Publication date Assignee Title
CN100442186C (en) * 2005-11-29 2008-12-10 杜国凯 Combined material level controller
CN100495277C (en) * 2006-01-18 2009-06-03 杜国凯 Novel composite position controller
CN102735311A (en) * 2012-06-18 2012-10-17 江苏中旗作物保护股份有限公司 Material level detecting device
CN102866089A (en) * 2012-08-31 2013-01-09 常熟市德虞矿山机电有限公司 Photoelectric signal collection conversion device for dust concentration sensor
CN108896132B (en) * 2018-05-08 2019-11-26 鲁东大学 Level gauging unit and material level gauge in a kind of RF admittance level meter
CN108896131B (en) * 2018-05-08 2019-11-26 鲁东大学 Level gauging unit and material level gauge in RF admittance level meter based on temperature-compensating

Citations (4)

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Publication number Priority date Publication date Assignee Title
US4800755A (en) * 1982-08-25 1989-01-31 Berwind Corporation Capacitance-type material level indicator
CN2185885Y (en) * 1993-05-28 1994-12-21 王成林 Asphalt liquid level sensor
US6191724B1 (en) * 1999-01-28 2001-02-20 Mcewan Thomas E. Short pulse microwave transceiver
CN2653462Y (en) * 2003-09-15 2004-11-03 杜家强 Radio frequency admittance level controller

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Publication number Priority date Publication date Assignee Title
US4800755A (en) * 1982-08-25 1989-01-31 Berwind Corporation Capacitance-type material level indicator
CN2185885Y (en) * 1993-05-28 1994-12-21 王成林 Asphalt liquid level sensor
US6191724B1 (en) * 1999-01-28 2001-02-20 Mcewan Thomas E. Short pulse microwave transceiver
CN2653462Y (en) * 2003-09-15 2004-11-03 杜家强 Radio frequency admittance level controller

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Title
射频电容式物位控制器 陈凤桂,彭炫,矿业研究与开发,第14卷第3期 1994 *

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