CN202903887U - Nitrogen-oxygen sensor heating detection circuit - Google Patents

Nitrogen-oxygen sensor heating detection circuit Download PDF

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Publication number
CN202903887U
CN202903887U CN201220456736.6U CN201220456736U CN202903887U CN 202903887 U CN202903887 U CN 202903887U CN 201220456736 U CN201220456736 U CN 201220456736U CN 202903887 U CN202903887 U CN 202903887U
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China
Prior art keywords
diode
well heater
triode
resistance
chip microcomputer
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Expired - Lifetime
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CN201220456736.6U
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Chinese (zh)
Inventor
谈洪亮
尹亮亮
宋巍
倪铭
于政
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Wuxi Longsheng Technology Co Ltd
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Wuxi Longsheng Technology Co Ltd
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Abstract

The utility model discloses a nitrogen-oxygen sensor heating detection circuit. The heating detection circuit comprises a heating circuit and a detecting circuit which are separately arranged to ensure precise measurement of the resistance value of a heater. A one-chip microcomputer is adopted to control the circuit to output heating voltages with adjustable duty ratios and further reflect the resistance value of the heater in a real-time manner through the detecting circuit. The aim of precisely controlling the temperature of the heater is thus achieved. By means of the nitrogen-oxygen sensor heating detection circuit provided by the utility model, the heating temperature of a nitrogen-oxygen sensor can be precisely controlled. The nitrogen-oxygen sensor is then made to work constantly in a stable-temperature-value condition.

Description

Nitrogen oxide sensor heating testing circuit
Technical field
The utility model relates to the nitrogen oxide sensor in a kind of motor car engine after-treatment system, relates in particular to a kind of heating testing circuit of nitrogen oxide sensor.
Background technology
Energy-saving and emission-reduction have become the common issue with that society faces, and various countries are also more and more higher to the requirement of air quality, and automotive emission has become main atmosphere pollution.At present, usually select nitrogen oxide sensor to measure the NOx concentration that contains in the tail gas that discharges in the motor car engine after-treatment system, and the NOx concentration value of measuring according to nitrogen oxide sensor takes appropriate measures, reduce the NOx gas purging, thereby make the tail gas of discharging meet the requirement of national standard.
The nitrogen oxide sensor chip is formed by semiotic function layer and well heater combination, and the semiotic function layer is mainly finished a series of galvanochemistry and cartalytic decomposition effect, to realize the measurement to NOx gas; Well heater mainly to the chip heating, makes it to reach the needed temperature of semiotic function layer galvanochemistry and catalytic reaction.The well heater of nitrogen oxide sensor adopts the three-wire type thermocouple structure more at present, and namely the head at thermopair is connected one for the potential electrode that gathers thermopair head resistance value with the power lead leading wire joint; Then further control the working temperature of nitrogen oxide sensor according to the resistance value of measuring, to guarantee the normal operation of nitrogen oxide sensor.Yet there is not at present the complete method that is used for Real-Time Monitoring and Reliable guarantee nitrogen oxide sensor working temperature of a cover.
Summary of the invention
The technical matters that the utility model solves provides a kind of nitrogen oxide sensor heating testing circuit, the duty that is used for control nitrogen oxide sensor three-wire type thermopair well heater can accurately be measured the content of Nox in the tail gas to guarantee nitrogen oxide sensor under specific temperature.
For solving the problems of the technologies described above, technical solution adopted in the utility model is as follows.
A kind of nitrogen oxide sensor heating testing circuit, the described heating testing circuit that is connected to three terminals of nitrogen oxide sensor well heater (H+, H-, A) comprises single-chip microcomputer and is subjected to monolithic processor controlled heater circuit and testing circuit;
Described heater circuit is used to the well heater heating, comprises heating power supply, and heating power supply is connected with the anodal H+ of well heater through triode T1, the negative pole H-ground connection of well heater; The base stage of triode T1 is connected with single-chip microcomputer through resistance R 6;
Described testing circuit is used for the resistance value of Real-Time Monitoring well heater, comprise the reference power supply module, the reference power supply module is connected with the anodal H+ of well heater through triode T2, diode D4, precision resistance R1 successively, and the base stage of triode T2 is connected with single-chip microcomputer through resistance R 7; The two ends of described precision resistance R1 connect respectively detection branch I and detection branch II, the measurement utmost point A of well heater connects a detection branch III, all through triode T3 ground connection, the base stage of triode T3 is connected with single-chip microcomputer through resistance R 8 output terminal of detection branch I, detection branch II and detection branch III.
The concrete structure of described detection branch is: described detection branch I comprises resistance R 2 and the diode D1 that is connected in series between diode D4 and the triode T3 collector, and the positive pole of diode D1 is connected with the AD1 of single-chip microcomputer end; The detection branch II comprises resistance R 3 and the diode D2 that is connected in series between the anodal H+ of well heater and the triode T3 collector, and the positive pole of diode D2 is connected with the AD2 of single-chip microcomputer end; The detection branch III comprises resistance R 4 and the diode D3 that is connected in series between well heater measurement utmost point A and the triode T3 collector, and the positive pole of diode D3 is connected with the AD3 of single-chip microcomputer end; Described diode D1, diode D2 are connected negative pole and all are connected through the output terminal of resistance R 5 with reference power supply module (IC) with diode D3.
Owing to adopted above technical scheme, the obtained technical progress of the utility model is as follows.
Heating testing circuit of the present utility model divides heater circuit and testing circuit and is arranged, and realizes that by monolithic heating process and testing process are in the duty of separation, thereby makes the resistance value of well heater calculate more accurate.The resistance value that single-chip microcomputer is learnt according to calculating is controlled the duty of heater circuit, has guaranteed that reliably nitrogen oxide sensor always works under the stable temperature, with the measurement of Nox in the further raising tail gas.
Description of drawings
Fig. 1 is circuit diagram of the present utility model.
Fig. 2 is heating dutycycle voltage and the detection voltage synoptic diagram that the utility model applies.
Embodiment
Below in conjunction with specific embodiments and the drawings, the utility model is further elaborated.
A kind of nitrogen oxide sensor heating testing circuit, as shown in Figure 1.The heating testing circuit is connected to three terminals of nitrogen oxide sensor well heater (H+, H-, A), comprises single-chip microcomputer M, heater circuit and testing circuit; Single-chip microcomputer M is used for the duty of control heater circuit and testing circuit.
Heater circuit is used to well heater to provide heating voltage to heat up, and makes nitrogen oxide sensor reach working temperature.Heater circuit comprises heating power supply U and triode T1, and heating power supply U is connected with the anodal H+ of well heater through triode T1, the negative pole H-ground connection of well heater; The base stage of triode T1 is connected with single-chip microcomputer M through resistance R 6.
Testing circuit, for detection of the real-time resistance of well heater, namely the feedback heater real time temperature is constantly regulated by single-chip microcomputer to single-chip microcomputer, makes nitrogen oxide sensor be in all the time fixing working temperature.Testing circuit comprises reference power supply module I C, and reference power supply module I C is connected with the anodal H+ of well heater through triode T2, diode D4, precision resistance R1 successively, and the base stage of triode T2 is connected with single-chip microcomputer M through resistance R 7.The diode D4 that is connected in series between precision resistance R1 and triode T2 is used for preventing that inverse current and reverse voltage from impacting triode T2, single-chip microcomputer M.
The two ends of above-mentioned precision resistance R1 connect respectively detection branch I and detection branch II, the measurement utmost point A of well heater connects a detection branch III, the output terminal of detection branch I, detection branch II and detection branch III is all through triode T3 ground connection, and the base stage of triode T3 is connected with single-chip microcomputer M through resistance R 8.The AD conversion port that being set to of detection branch prevents single-chip microcomputer substantially exceeds itself at the voltage of heating period and maximumly allows input voltage and damage single-chip microcomputer.
The detection branch I comprises resistance R 2 and the diode D1 that is connected in series between diode D4 and the triode T3 collector, and the positive pole of diode D1 is connected with the AD1 end of single-chip microcomputer M; The detection branch II comprises resistance R 3 and the diode D2 that is connected in series between the anodal H+ of well heater and the triode T3 collector, and the positive pole of diode D2 is connected with the AD2 end of single-chip microcomputer M; Single-chip microcomputer is determined the magnitude of voltage Ue at precision resistance R1 two ends according to the voltage signal of sampled point AD1 and AD2 collection.The detection branch III comprises resistance R 4 and the diode D3 that is connected in series between well heater measurement utmost point A and the triode T3 collector, and the positive pole of diode D3 is connected with the AD3 end of single-chip microcomputer M; Single-chip microcomputer is determined the magnitude of voltage U at well heater two ends according to the voltage signal of sampled point AD2 and AD3 collection TAbove-mentioned diode D1, diode D2 are connected negative pole and all are connected through the output terminal of resistance R 5 with reference power supply module I C with diode D3, be used for preventing that when detecting, generation current on resistance R 2, resistance R 3, the resistance R 4 exerts an influence to the result who measures.
Nitrogen oxide sensor heating detection method described in the utility model based on above-mentioned heating testing circuit, may further comprise the steps:
1) single-chip microcomputer sends to well heater according to fixed frequency and detects voltage U 1 and heating voltage U2, as shown in Figure 2.Detecting voltage U 1 is normal voltage Vcc, and dutycycle immobilizes, in case final measurement result is exerted an influence; Heating voltage U2 is adjustable voltage, and the adjusting of its dutycycle size is to be controlled by the real-time resistance that detects the well heater that feeds back by single-chip microcomputer M.
When 2) heating, Single-chip Controlling triode T2 shutoff, triode T1 and triode T 3 conductings, then heating power supply U through well heater negative pole H ﹣ arrival reference ground, finishes heating process through the anodal H ﹢ that triode T1 arrives well heater.
Because divider resistance R2, R3, R4, the acting in conjunction of diode D1, D2, D3 and triode T2, T3 so that the voltage at sampled point AD1, AD2, AD3 place is no more than 1.5V, thereby has been protected the AD conversion port of single-chip microcomputer M well.
In the heating process, heating voltage adopts the dutycycle voltage applying mode, and the size of heating voltage U2 is determined by the ON time of single-chip microcomputer M control triode T1.At the heating initial stage, dutycycle is larger, and the heating voltage that namely is carried in nitrogen oxide sensor well heater two ends is larger, and the nitrogen oxide sensor ceramic chip is heated up rapidly, makes as early as possible nitrogen oxide sensor reach duty; Along with the heating carrying out, the heater resistance value of nitrogen oxide sensor diminishes, thus the heating voltage U2 that applies constantly diminish, to prevent that excessive electric current is to the well heater injury; When the well heater resistance arrives a setting value, when namely nitrogen oxide sensor had been heated to required working temperature, single-chip microcomputer M control heating voltage U2 fixed.
In the nitrogen oxide sensor course of work, when the residing environment temperature of nitrogen oxide sensor fluctuates to some extent, single-chip microcomputer also can be controlled heating voltage U2 in good time and carry out suitable increase or reduction, to keep the resistance of well heater, so that the working temperature of nitrogen oxide sensor stabilizes to certain value.
When 3) detecting, single-chip microcomputer M control triode T2 conducting, triode T1 and T3 turn-off, be that heating voltage U2 is disconnected from the circuit by triode T1 and quits work, and this moment voltage module IC outputting standard voltage vcc, normal voltage Vcc arrives the anodal H ﹢ of well heater, measures utmost point A, well heater negative pole H ﹣ ground connection through triode T2, diode D4, precision resistance R1 successively.In the testing process, single-chip microcomputer is sampled according to sampled point AD1, AD2 and is obtained the voltage U e at precision resistance R1 two ends, by the electric current I of formula I=Ue/R1 Flow through precision resistance R1; At this moment, sampling obtains the both end voltage U of well heater according to sampled point AD2, AD3 for the electric current of the R1 that flows through equal the to flow through electric current of well heater T, single-chip microcomputer T, according to formula R=U T/ I calculates the resistance value of well heater; Because the resistance value of well heater and the working temperature of nitrogen oxide sensor have one-to-one relationship, therefore get the resistance value of from heater core, can draw the working temperature of current nitrogen oxide sensor.
4) single-chip microcomputer is according to the heater resistance value that calculates, and the control heater circuit starts, and regulates heating voltage U2 according to the difference of resistance value and standard electric resistance, makes well heater keep stable working temperature.Single-chip microcomputer M reaches the dutycycle size of control heating voltage U2 in the utility model by the length of power ratio control triode T1 ON time.

Claims (2)

1. a nitrogen oxide sensor heating testing circuit comprises well heater, and it is characterized in that: the well heater of described nitrogen oxide sensor is provided with three terminals, and three terminals are respectively anodal H+, negative pole H-and measure utmost point A; Described heating testing circuit is connected between three terminals of nitrogen oxide sensor well heater, heater circuit and testing circuit that the heating testing circuit comprises single-chip microcomputer (M) and is subjected to single-chip microcomputer (M) control;
Described heater circuit is used to the well heater heating, comprises heating power supply (U), and heating power supply (U) is connected with the anodal H+ of well heater through triode T1, the negative pole H-ground connection of well heater; The base stage of triode T1 is connected with single-chip microcomputer (M) through resistance R 6;
Described testing circuit is used for the resistance value of Real-Time Monitoring well heater, comprise reference power supply module (IC), reference power supply module (IC) is connected with the anodal H+ of well heater through triode T2, diode D4, precision resistance R1 successively, and the base stage of triode T2 is connected with single-chip microcomputer (M) through resistance R 7; The two ends of described precision resistance R1 connect respectively detection branch I and detection branch II, the measurement utmost point A of well heater connects a detection branch III, the output terminal of detection branch I, detection branch II and detection branch III is all through triode T3 ground connection, and the base stage of triode T3 is connected with single-chip microcomputer (M) through resistance R 8.
2. nitrogen oxide sensor according to claim 1 heats testing circuit, it is characterized in that: described detection branch I comprises resistance R 2 and the diode D1 that is connected in series between diode D4 and the triode T3 collector, and the positive pole of diode D1 is connected with the AD1 end of single-chip microcomputer (M); The detection branch II comprises resistance R 3 and the diode D2 that is connected in series between the anodal H+ of well heater and the triode T3 collector, and the positive pole of diode D2 is connected with the AD2 end of single-chip microcomputer (M); The detection branch III comprises resistance R 4 and the diode D3 that is connected in series between well heater measurement utmost point A and the triode T3 collector, and the positive pole of diode D3 is connected with the AD3 end of single-chip microcomputer (M); Described diode D1, diode D2 are connected negative pole and all are connected through the output terminal of resistance R 5 with reference power supply module (IC) with diode D3.
CN201220456736.6U 2012-09-08 2012-09-08 Nitrogen-oxygen sensor heating detection circuit Expired - Lifetime CN202903887U (en)

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102854393A (en) * 2012-09-08 2013-01-02 无锡隆盛科技股份有限公司 Heating detecting circuit and heating detecting method for nitrogen and oxygen sensor
CN104932583A (en) * 2015-04-30 2015-09-23 湖北丹瑞新材料科技有限公司 Nitrogen oxygen sensor heating detection apparatus and control method thereof
DE102020204213A1 (en) 2020-04-01 2021-10-07 Vitesco Technologies GmbH Method for determining a state parameter of an exhaust gas sensor

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102854393A (en) * 2012-09-08 2013-01-02 无锡隆盛科技股份有限公司 Heating detecting circuit and heating detecting method for nitrogen and oxygen sensor
CN102854393B (en) * 2012-09-08 2014-12-24 无锡隆盛科技股份有限公司 Heating detecting circuit and heating detecting method for nitrogen and oxygen sensor
CN104932583A (en) * 2015-04-30 2015-09-23 湖北丹瑞新材料科技有限公司 Nitrogen oxygen sensor heating detection apparatus and control method thereof
DE102020204213A1 (en) 2020-04-01 2021-10-07 Vitesco Technologies GmbH Method for determining a state parameter of an exhaust gas sensor

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Granted publication date: 20130424