CN102103107B - Detection instrument for detecting quality of lubricating oil by capacity effect and detection method thereof - Google Patents
Detection instrument for detecting quality of lubricating oil by capacity effect and detection method thereof Download PDFInfo
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- CN102103107B CN102103107B CN 200910201239 CN200910201239A CN102103107B CN 102103107 B CN102103107 B CN 102103107B CN 200910201239 CN200910201239 CN 200910201239 CN 200910201239 A CN200910201239 A CN 200910201239A CN 102103107 B CN102103107 B CN 102103107B
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Abstract
The invention relates to a detection instrument for detecting the quality of lubricating oil by a capacity effect and a detection method thereof. The detection instrument comprises: a control module, an analog-to-digital conversion module and an electronic switch circuit which are connected with the control module, a comparison circuit an output end of which is connected with the control module, a conversion module, a working power supply and a detected capacitor which are connected with the electronic switch circuit, and a reference voltage connected with the analog-to-digital conversion module and an input end of the comparison circuit, wherein the detected capacitor is connected with the electronic switch circuit and further connected with the input end of the comparison circuit, one end of the detected capacitor is connected with the conversion module, and the output end of the conversion module is connected with the analog-to-digital conversion module. The detection instrument of the invention is simple in structure and fast in detection ways; the high-speed analog-to-digital conversion circuit is arranged to implement synchronous sampling and the detected capacitor is connected with a virtual earth end of a charge amplification circuit, thereby eliminating stray capacitances at two ends of the detected capacitor; the electronic switch is arranged for realizing switching-on and switching-off respectively, thereby removing the influence caused by charge injection, and environmental influence is corrected in software to result in high resolution and high precision.
Description
Technical field
The present invention relates to a kind of lubricating oil detection technique, be specifically related to a kind of detector and detection method thereof of utilizing capacity effect to detect lubricating oil quality.
Background technology
At present, can ask professional institution to detect the variation of lubricating oil specific inductive capacity after using certain hour, but sense cycle is longer.Similar detection technique on the market has been reduced life cycle, yet relatively backward, precision is not high, for example, having a kind of is to adopt constant voltage to modulate the square-wave waveform that obtains discharging and recharging by resistance in series to the measured capacitance charging and by 555 timers, and then filtering obtains the way that can carry out the voltage signal of analogue technique measurement, measure out of true, can only reach 5% precision, its shortcoming have following some:
1. not constant-current charge, can't obtain the linear-charging curve, cause the testing result out of true;
2. measured capacitance is very little, about tens pF, therefore charging is very fast, the waveform of charging process is very narrow, causes the testing result out of true;
3. in the process to the measured capacitance charging, inevitable peripherad stray capacitance has also been filled electricity simultaneously, causes containing in the resulting charge waveforms noisy part;
4. do not consider temperature parameter in the computing technique, do not eliminate the impact that humiture changes, cause error large.
Summary of the invention
The invention provides a kind of detector and detection method thereof of utilizing capacity effect to detect lubricating oil quality, detect simple and effectively, can obtain the high precision testing result.
For achieving the above object, the invention provides a kind of detector that utilizes capacity effect to detect lubricating oil quality, this detector comprises control module; The analog-to-digital conversion module, the electronic switching circuit that are connected with the control module circuit respectively; The comparator circuit that output terminal is connected with this control module; The modular converter, working power and the measured capacitance that are connected with this electronic switching circuit circuit respectively; The reference voltage circuit that connects the input end of this analog-to-digital conversion module and comparator circuit; This measured capacitance, an end of its connecting electronic on-off circuit also is connected with another input end of comparator circuit, and this measured capacitance other end connects the input end of modular converter; The output terminal of this modular converter is connected with the input end of analog-to-digital conversion module;
Above-mentioned modular converter comprises charge amplifying circuit and signal modulation circuit, the input end of this charge amplifying circuit is connected with measured capacitance, the output terminal of this charge amplifying circuit is connected with the input end of signal modulation circuit, and the output terminal of this signal modulation circuit connects the input end of analog-to-digital conversion module; This charge amplifying circuit comprises charge amplifier, and the feedback capacity Cf that is connected in parallel with charge amplifier.
Above-mentioned detector also comprises display module and the key control module that is connected with this circuit of control module respectively.
Above-mentioned measured capacitance comprises the measured capacitance container, is provided with comb type tinsel in this measured capacitance container, and tested lubricating oil is contained in the measured capacitance container as condenser dielectric, forms measured capacitance with described tinsel.
A kind of be used to utilizing capacity effect to detect the detection method of the detector of lubricating oil quality, this detector comprises control module; The analog-to-digital conversion module, the electronic switching circuit that are connected with the control module circuit respectively; The comparator circuit that output terminal is connected with this control module; The modular converter, working power and the measured capacitance that are connected with this electronic switching circuit circuit respectively; The reference voltage circuit that connects the input end of this analog-to-digital conversion module and comparator circuit; This measured capacitance, an end of its connecting electronic on-off circuit also is connected with another input end of comparator circuit, and this measured capacitance other end connects the input end of modular converter; The output terminal of this modular converter is connected with the input end of analog-to-digital conversion module;
Above-mentioned modular converter comprises charge amplifying circuit and signal modulation circuit, the input end of this charge amplifying circuit is connected with measured capacitance, the output terminal of this charge amplifying circuit is connected with the input end of signal modulation circuit, and the output terminal of this signal modulation circuit connects the input end of analog-to-digital conversion module; This charge amplifying circuit comprises charge amplifier, and the feedback capacity Cf that is connected in parallel with charge amplifier;
Above-mentioned measured capacitance comprises the measured capacitance container;
The method includes the steps of:
Before step 1, the detection, place an amount of tested lubricating oil in the measured capacitance container, the electronic switch for controlling circuit fully discharges to measured capacitance;
Step 2, begin to detect, the electronic switch for controlling circuit makes working power charge to measured capacitance;
The voltage signal that step 3, modular converter output are directly proportional with the appearance value of measured capacitance;
Step 3.1, charge amplifying circuit are converted into the voltage signal that is directly proportional with it with the appearance value signal of measured capacitance;
Step 3.2, signal modulation circuit are regulated the voltage signal of charge amplifying circuit output.
Step 4, comparator circuit are judged the reference voltage whether measured capacitance voltage provide greater than reference voltage circuit, if, jump to step 5, if not, jump to step 4.1;
Step 4.1, control module control analog-to-digital conversion module are not worked, and are jumped to step 4;
Step 5, control module control analog-to-digital conversion module carry out analog to digital conversion to the voltage signal of modular converter output, and the result are outputed to control module;
Step 6, control module are calculated the appearance value Cx of measured capacitance according to the relation of the voltage signal of the appearance value of measured capacitance and modular converter output:
Cx＝-(Vo/Vi)*Cf；
Wherein, Vi is the voltage on the measured capacitance, and Vo is the charge amplifying circuit output voltage, and Cf is the appearance value of feedback capacity;
The deviation ratio that step 6.1, control module (21) multiply by the appearance value Cx of measured capacitance (22) capacitance under standard environment and the current detection environment comes correction result, evades environmental impact;
Step 7, relatively the appearance value of tested lubricating oil and the standard appearance value of lubricating oil in the measured capacitance are judged the quality of tested lubricating oil.
The detector that the present invention utilizes capacity effect to detect lubricating oil quality is compared with existing detector, and its advantage is, detector of the present invention is simple in structure, and detection means is effectively quick;
The present invention is provided with high-speed A/D conversion circuit and carries out synchronized sampling, high-speed capture available point voltage, so that the resolution of capacitance detecting reaches 0.025pF, and precision reaches 0.1pF, is higher than 0.5%;
Measured capacitance connects the virtual earth end of charge amplifying circuit among the present invention, has eliminated the stray capacitance at measured capacitance two ends, improves precision;
The present invention is provided with electronic switch and opens respectively shutoff, and analog to digital conversion circuit carries out synchronized sampling, has eliminated the impact of charge injection, has improved the circuit signal to noise ratio (S/N ratio);
Be provided with the school Z-operation in the software of the present invention, revised the impact of environment, improve precision.
Description of drawings
Fig. 1 is that the present invention utilizes capacity effect to detect the circuit block diagram of the detector of lubricating oil quality;
Fig. 2 is that the present invention utilizes capacity effect to detect the circuit diagram of the detector of lubricating oil quality;
Fig. 3 is that the present invention utilizes capacity effect to detect the detection method process flow diagram of the detector of lubricating oil quality.
Embodiment
Further specify embodiments of the invention below in conjunction with accompanying drawing.
See also shown in Figure 1ly, the Circuits System 2 that the present invention utilizes capacity effect to detect the detector of lubricating oil quality comprises the output terminal of control module 21, the analog-to-digital conversion module 26 that is connected with control module 21 respectively, electronic switching circuit 23, display module 11, key control module 12 and comparator circuit 28; Wherein electronic switching circuit 23 also is connected with measured capacitance with modular converter 25, working power 24 respectively and is connected; Measured capacitance 22, an end of its connecting valve circuit 23 also is connected with the input end of comparator circuit 28, and these measured capacitance 22 other ends connect the input end of modular converter 25; The output terminal of modular converter 25 is connected with the input end of analog-to-digital conversion module 26, and analog-to-digital conversion module 26 also connects reference voltage circuit 27, and this reference voltage circuit 27 also connects another input end of comparator circuit 28.Wherein working power 24 also provides stabilized power source to each functional module respectively.
The physical circuit principle sees also Fig. 2, and wherein detector also is provided with measured capacitance container 221; Measured capacitance container 221 is a circular trough, on its inwall to being inserted with two groups of mutual unconnected comb type tinsels, and in measured capacitance container 221, place lubricating oil, comb type tinsel and tested lubricating oil form capacitance structure, and are connected in the Circuits System 2 as measured capacitance 22.Electronic switching circuit 23 adopts the chip I SL84053 of intersil company, comprises electronic switch S1, electronic switch S2 and electronic switch S3 in this circuit; The end of electronic switch S1 be connected the output terminal of 3.6V working power 24 of capacitive transducer exciting signal source and connect, 3.6V working power 24 also provides stabilized power source to each functional module respectively simultaneously.And the other end of electronic switch S1 respectively with the end of electronic switch S2, one of the end of measured capacitance 22Cx and input of comparator circuit 28 connect, the other end ground connection of electronic switch S2 wherein, comparator circuit 28 adopts the LM311 voltage comparator of TI company, the input end that the other end of measured capacitance Cx is connected with modular converter connects, modular converter 25 comprises charge amplifying circuit 251 and signal modulation circuit 252, the input end of this charge amplifying circuit 251 is connected with measured capacitance 22, the output terminal of this charge amplifying circuit 251 is connected with the input end of signal modulation circuit 252, and the output terminal of this signal modulation circuit 252 connects the input end of analog-to-digital conversion module 26.Charge amplifying circuit 251 comprises TLV2462 charge amplifier and feedback capacity Cf that TI company produces, signal modulation circuit 252 is an inverting amplifier, the negative input end of TLV2462 charge amplifier is connected with measured capacitance Cx, its positive input terminal ground connection, its output terminal is connected with the input end of inverting amplifier, measured capacitance Cx also the be connected in parallel end of feedback capacity Cf and the end of electronic switch S3, the other end of the other end of feedback capacity Cf, electronic switch S3 and the output terminal of TLV2462 charge amplifier are in parallel.The output terminal of inverting amplifier is connected with the input end of analog-to-digital conversion module 26, analog-to-digital conversion module 26 is an analog to digital converter, the Voltage Reference end of analog to digital converter also accesses 2.5V reference voltage 27, and this 2.5V reference voltage 27 connects another input of LM311 voltage comparator simultaneously.Control module 21 adopts the dsPIC33F710 singlechip chip of microchip company, the output terminal of the output terminal of analog to digital converter and LM311 voltage comparator accesses respectively the dsPIC33F710 single-chip microcomputer, single-chip microcomputer is also controlled analog to digital converter simultaneously, the dsPIC33F710 single-chip microcomputer also connects respectively, and control LCDs, five buttons and electronic switch S1, S2 and S3.
Illustrate that below in conjunction with Fig. 3 the present invention utilizes capacity effect to detect the detection method of the detector of lubricating oil quality:
Before step 1 detects, in measured capacitance container 221, place an amount of tested lubricating oil, make tested lubricating oil connect into Circuits System 2 as capacitor dielectric, and electronic switch for controlling circuit 23, closed electronics switch S 2 and electronic switch S3, and disconnect electronic switch S1, and measured capacitance Cx is fully discharged, eliminate the charge injection impact;
Step 2 begins to detect, and electronic switch for controlling circuit 23 disconnects electronic switch S2 and electronic switch S3, and closed electronics switch S 1, finishes capacitor C x discharge, and working power 24 is charged to measured capacitance 22 with several uA electric currents;
The voltage signal that 25 outputs of step 3 modular converter are directly proportional with measured capacitance 22 appearance values;
Step 3.1 is according to the principle of work of charge amplifier charge conservation, and feedback capacity Cf begins the repercussion charging, and charge amplifying circuit 251 is converted into the voltage signal Vo that is directly proportional with it with the appearance value Cx signal of measured capacitance 22,
Relational expression is as follows: Cx=-(Vo/Vi) * Cf;
Wherein Vi is the voltage on the measured capacitance 22, and Cx is the appearance value of measured capacitance 22, and Vo is the charge amplifier output voltage, and Cf is the appearance value of feedback capacity;
The voltage signal Vo of step 3.2 signal modulation circuit 252 arrangement charge amplifying circuit 251 outputs, signal modulation circuit 252 is inverting amplifier, signal modulation circuit 252 is on the occasion of signal with the voltage reversal of the negative value of charge amplifier output, and this signal is transferred to analog-to-digital conversion module 26;
Step 4 while, measured capacitance 22 voltage signals are introduced into high speed voltage comparator one input end, another input end access of this comparer 2.5V reference voltage, comparator circuit 28 judges that whether measured capacitance 22 voltages are greater than reference voltage 27, if jump to step 5, if not, jump to step 4.1;
Step 4.1 control module 21 control analog-to-digital conversion modules 26 are not worked, and jump to step 4 and rejudge the 2.5V whether measured capacitance 22 voltages surpass reference voltage 27;
The LM311 high speed voltage comparator upset of step 5 comparator circuit 28, it exports the I/O external interrupt pin of control module dsPIC33F710 single-chip microcomputer to, trigger singlechip interruption, single-chip microcomputer enters interrupt service routine, the voltage signal of 26 pairs of modular converters of Single-chip Controlling analog-to-digital conversion module, 25 outputs is carried out the synchronized sampling analog to digital conversion of sampling rate 1M, obtain analog to digital conversion value ADo and input single-chip microcomputer, single-chip microcomputer is by electronic switching circuit 23 subsequently, to measured capacitance 22 discharges, finish once check;
Step 6 control module 21 is utilized the relational expression of the voltage signal Vo of measured capacitance 22 appearance value Cx and modular converter 25 outputs in the step 3, calculates measured capacitance 22 appearance values.Because measured capacitance 22 appearance value Cx are very little, are tens pF, therefore feedback capacity Cf is set to 100pF; Single-chip microcomputer obtains A/D conversion value ADo, and Vi and Vo can be with the representative of A/D conversion value, therefore Vo=ADo; And owing to adopting 12 A/D converters, its mxm. is 2 12 powers, is 4096, so Vi=4096; Can calculate Cx by relational expression and above each value; Owing to being provided with the school Z-operation in the embedded software of single-chip microcomputer, can carry out the measured value correction to the Cx that calculates according to the school null value under the standard environment, evade the impact that temperature humidity changes with this, final gained is the appearance value Cx of the measured capacitance 22 of tested lubricating oil composition;
Its school Z-operation is as follows: " school zero " is for measuring capacitor " clean electric capacity ", it is the value that does not add any tested oil product in the measured capacitance container 221, the environmental factor that has comprised there and then in this value is such as the impact on measured capacitance amount size such as temperature, humidity, air pressure.This instrument in use carries out " school zero " operation to instrument in advance under standard environment, obtain the value under the standard environment; Then before ensuing each detection, under residing environment, carry out " school zero " operation of instrument, this operation can be carried out automatically by the instrument screen prompting, can obtain like this two school null values, one is the value under the standard environment condition, one is the value under the environmental baseline when detecting, can draw the deviation ratio of two values, the deviation ratio of these two values namely can be used to the testing result of back is suitably revised, testing result be multiply by this deviation ratio, can obtain the capacitance of tested lubricating oil under standard environment;
The appearance value Cx of tested lubricating oil carries out the lubricating oil standard appearance value of " calibration " gained with adopting in advance standard oil sample in this instrument of step 7 comparison measured capacitance 22 to the standard value of this model oil product, judge the quality of tested lubricating oil with this, this lubricating oil standard appearance value detects and is kept at instrument internal in advance.
Although content of the present invention has been done detailed introduction by above preferred embodiment, will be appreciated that above-mentioned description should not be considered to limitation of the present invention.After those skilled in the art have read foregoing, for multiple modification of the present invention with to substitute all will be apparent.Therefore, protection scope of the present invention should be limited to the appended claims.
Claims (6)
1. a detector that utilizes capacity effect to detect lubricating oil quality is characterized in that, this detector comprises:
Control module (21);
The analog-to-digital conversion module (26), the electronic switching circuit (23) that are connected with control module (21) circuit respectively;
The comparator circuit (28) that output terminal is connected with described control module (21);
The modular converter (25), working power (24) and the measured capacitance (22) that are connected with described electronic switching circuit (23) circuit respectively;
The reference voltage circuit (27) that connects the input end of described analog-to-digital conversion module (26) and comparator circuit (28);
Described measured capacitance (22), an end of its connecting electronic on-off circuit (23) also are connected with another input end of comparator circuit (28), and this measured capacitance (22) other end connects the input end of modular converter (25);
The output terminal of described modular converter (25) is connected with the input end of analog-to-digital conversion module (26);
Described modular converter (25) comprises charge amplifying circuit (251) and signal modulation circuit (252),
The input end of this charge amplifying circuit (251) is connected with measured capacitance (22), the output terminal of this charge amplifying circuit (251) is connected with the input end of signal modulation circuit (252), and the output terminal of this signal modulation circuit (252) connects the input end of analog-to-digital conversion module (26); Described charge amplifying circuit (251) comprises charge amplifier, and the feedback capacity in parallel with charge amplifier (Cf).
2. the detector that utilizes capacity effect to detect lubricating oil quality as claimed in claim 1, it is characterized in that, described detector also comprises display module (11) and the key control module (12) that is connected with control module (21) circuit respectively.
3. the detector that utilizes capacity effect to detect lubricating oil quality as claimed in claim 1, it is characterized in that, described measured capacitance (22) comprises measured capacitance container (221), be provided with comb type tinsel in this measured capacitance container (221), tested lubricating oil is contained in the measured capacitance container (221) as condenser dielectric, forms measured capacitance (22) with described tinsel.
4. one kind is used for utilizing capacity effect to detect the detection method of the detector of lubricating oil quality as described in claim 1, and this detector comprises:
Control module (21);
The analog-to-digital conversion module (26), the electronic switching circuit (23) that are connected with control module (21) circuit respectively;
The comparator circuit (28) that output terminal is connected with described control module (21);
The modular converter (25), working power (24) and the measured capacitance (22) that are connected with described electronic switching circuit (23) circuit respectively;
The reference voltage circuit (27) that connects the input end of described analog-to-digital conversion module (26) and comparator circuit (28);
Described measured capacitance (22), an end of its connecting electronic on-off circuit (23) also are connected with another input end of comparator circuit (28), and this measured capacitance (22) other end connects the input end of modular converter (25);
The output terminal of described modular converter (25) is connected with the input end of analog-to-digital conversion module (26);
Described modular converter (25) comprises charge amplifying circuit (251) and signal modulation circuit (252), the input end of this charge amplifying circuit (251) is connected with measured capacitance (22), the output terminal of this charge amplifying circuit (251) is connected with the input end of signal modulation circuit (252), and the output terminal of this signal modulation circuit (252) connects the input end of analog-to-digital conversion module (26); Described charge amplifying circuit (251) comprises charge amplifier, and the feedback capacity in parallel with charge amplifier (Cf);
Described measured capacitance (22) comprises measured capacitance container (221);
It is characterized in that, the method includes the steps of:
Before step 1, the detection, place an amount of tested lubricating oil in measured capacitance container (221), electronic switch for controlling circuit (23) is to fully discharge of measured capacitance (22);
Step 2, begin to detect, electronic switch for controlling circuit (23) makes working power (24) charge to measured capacitance (22);
The voltage signal that step 3, modular converter (25) output are directly proportional with the appearance value of measured capacitance (22);
Step 4, comparator circuit (28) are judged the reference voltage (27) whether measured capacitance (22) voltage provide greater than reference voltage circuit (27), if, jump to step 5, if not, jump to step 4.1;
Step 4.1, control module (21) control analog-to-digital conversion module (26) are not worked, and are jumped to step 4;
Step 5, control module (21) control analog-to-digital conversion module (26) carry out analog to digital conversion to the voltage signal of modular converter (25) output, and the result are outputed to control module (21);
Step 6, control module (21) are calculated the appearance value Cx of measured capacitance (22) according to the relation of the voltage signal of the appearance value of measured capacitance (22) and modular converter (25) output:
Cx＝-(Vo/Vi)*Cf；
Wherein, Vi is the voltage on the measured capacitance (22), and Vo is the output voltage of charge amplifying circuit (251), and Cf is the appearance value of feedback capacity;
Step 7, relatively the appearance value of tested lubricating oil and the standard appearance value of lubricating oil in the measured capacitance (22) are judged the quality of tested lubricating oil.
5. as claimed in claim 4ly it is characterized in that be used to utilizing capacity effect to detect the detection method of the detector of lubricating oil quality, described step 3 also comprises following steps:
Step 3.1, charge amplifying circuit (251) are converted into the voltage signal that is directly proportional with it with the appearance value signal of measured capacitance (22);
Step 3.2, signal modulation circuit (252) are regulated the voltage signal of charge amplifying circuit (251) output.
6. as claimed in claim 4ly it is characterized in that be used to utilizing capacity effect to detect the detection method of the detector of lubricating oil quality, described step 6 also comprises following steps:
The deviation ratio that step 6.1, control module (21) multiply by the appearance value Cx of measured capacitance (22) capacitance under standard environment and the current detection environment comes correction result, evades environmental impact.
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| CN 200910201239 CN102103107B (en) | 2009-12-16 | 2009-12-16 | Detection instrument for detecting quality of lubricating oil by capacity effect and detection method thereof |
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| CN 200910201239 CN102103107B (en) | 2009-12-16 | 2009-12-16 | Detection instrument for detecting quality of lubricating oil by capacity effect and detection method thereof |
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| CN102103107B true CN102103107B (en) | 2013-01-02 |
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Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN102998360B (en) * | 2012-12-25 | 2015-03-04 | 重庆勤智科技有限公司 | Online testing method for aging of transformer insulating oil based on electric field induction |
| CN103986886A (en) * | 2014-05-21 | 2014-08-13 | 芜湖蓝宙电子科技有限公司 | Racing track information collecting circuit based on linear CCD module |
| CN105158581B (en) * | 2015-09-28 | 2018-01-16 | 国网甘肃省电力公司 | Large bulk capacitance cubic content measurement circuit |
| CN108693336B (en) * | 2018-06-06 | 2021-09-07 | 北京雅士科莱恩石油化工有限公司 | Lubricating oil film level tester and testing method thereof |
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