CN102798654A - Heating control method for nitrogen oxygen sensor - Google Patents

Abstract

The invention discloses a heating control method for a nitrogen oxygen sensor. The nitrogen oxygen sensor comprises a signal function layer and a heater, wherein the heater is of a three-line type heater structure. The heating method comprises the following specific steps of: a, drawing a graph of a temperature value T of a nitrogen oxygen sensor chip and a head resistance value of the heater; b, when the temperature of the nitrogen oxygen sensor chip is determined to be 800DEG C, determining a resistance calibration value of the heater head to be R 800 and a voltage calibration value of the heater to be V800; and c, adjusting a heating voltage value of the heater for enabling a temperature value of the nitrogen oxygen sensor chip to be maintained at 800DEG C. According to the heating control method disclosed by the invention, the temperature value change of the head of the nitrogen oxygen sensor chip is characterized by adopting the amplitude of the head resistance value of the heater; and a work temperature value of the nitrogen oxygen sensor chip is enabled to be controlled at about 800DEG C by changing voltage values applied to two ends of the heater, and thus the measurement precision of the nitrogen oxygen sensor for NOx is further improved.

Description

The nitrogen oxide sensor method for heating and controlling

Technical field

The present invention relates to a kind of large diesel engine SCR system and use nitrogen oxide sensor, relate in particular to a kind of method for heating and controlling of nitrogen oxide sensor.

Background technology

The nitrogen oxide sensor chip is by 6 layers of 5%molY ₂O ₃Stable Zirconia electrolytic is formed by stacking, and is formed by semiotic function layer and well heater combination, and the semiotic function layer mainly accomplishes a series of galvanochemistry and cartalytic decomposition effect is realized the measurement to NOx gas; Mainly heating makes it to reach semiotic function layer galvanochemistry and the needed temperature of catalytic reaction to well heater to chip.The semiotic function layer is made up of three pump batteries, two cavitys, a reference air duct.Slit communicates with extraneous measurement gas two cavitys through spreading, the reference air duct is direct and atmosphere.A main pump battery is arranged in first cavity, the oxygen in first cavity is pumped outside the chamber, and the oxygen in first cavity is maintained about 1000ppm through measurement and feedback to V0; An auxiliary pumping cell and a measurement pump battery are arranged in second cavity, and auxiliary pumping cell further pumps the oxygen in second cavity outside the chamber, and through measurement and the feedback to V1 the oxygen in second chamber is maintained about several ppm.NOx gas in second cavity resolves into oxygen and nitrogen under the catalytic action of potential electrode, the measured pump of the oxygen of decomposition is extracted out outside the chamber, and the pump electric current that is produced is represented the concentration of NOx in the measurement gas.

The working temperature of nitrogen oxide sensor is 800 ℃, and nitrogen oxide sensor is measuring NOx concentration under this high temperature.Measuring process is: 1) in first cavity, because the oxygen in the cavity is taken away NO and NO continually by main pump ₂Between chemical equilibrium broken.Decomposition reaction: NO takes place ₂Be decomposed into NO and oxygen O ₂In the decomposition reaction generating process,, can not cause the decomposition of NO because the oxygen concentration in first cavity remains in the constant scope.Simultaneously, the HC in the tail gas, CO, H ₂Deng inflammable gas oxidizing fire under the catalytic action of Pt electrode.2) in second cavity the inside, because the further pump oxygen of service pump makes the oxygen concentration in second cavity continue to reduce, add the catalytic action of potential electrode, make that decomposition reaction takes place on potential electrode the NO in the measured gas: NO is decomposed into N ₂And O ₂3) O that is decomposed in second chamber ₂The continuous pump in measured pumping source source is walked, and the pump electric current of generation is corresponding with the concentration of NO, and the NO concentration of this moment also is the concentration of NOx in the measured gas.

Realize in the process to the NOx measurement of concetration at the nitrogen oxide sensor chip, the control of nitrogen oxide sensor chip temperature is played crucial effects.The well heater of traditional nitrogen oxide sensor adopts the mode of two lines heating; Apply the working temperature that a constant voltage makes it to reach nitrogen oxide sensor to well heater; When exhaust temperature changed between 300 ℃-800 ℃, the temperature of nitrogen oxide sensor chip also produced a bigger temperature fluctuation thereupon.And for the nitrogen oxide sensor of current mode, when chip temperature changes, can influence the family curve of nitrogen oxide sensor pump electric current and pump voltage, cause the measuring error of measuring the pump electric current; In addition, if the nitrogen oxide sensor chip temperature does not reach 800 ℃, then can influence the catalytic decomposition ability of potential electrode to NOx, these two kinds of factors all can cause nitrogen oxide sensor that the measurement of NOx gas is produced error.

Summary of the invention

The technical matters that the present invention solves provides a kind of method for heating and controlling of nitrogen oxide sensor, to reach nitrogen oxide sensor under different exhaust temperature environment, accurately measures the purpose of NOx concentration in the measured gas.

For solving the problems of the technologies described above, the technical scheme that the present invention taked is following.

The nitrogen oxide sensor method for heating and controlling; The well heater that said nitrogen oxide sensor comprises the semiotic function layer and is positioned at semiotic function layer below; Lead-in wire A and lead-in wire B that said well heater comprises heater head and connects the heater head two ends respectively; The voltage of said well heater applies and is provided with the potential electrode C that is used to gather the heater head resistance value between the end, and the end of said potential electrode C is connected the junction of heater head and lead-in wire A or lead-in wire B; Said method for heating and controlling is specially:

A. draw the temperature value T of nitrogen oxide sensor chip and the curve map between the heater head resistance value;

When confirming that b. the nitrogen oxide sensor chip temperature is 800 ℃, the resistance calibration value R of heater head ₈₀₀, the heating voltage calibration value of well heater is V ₈₀₀

C. according to the actual temperature value of detection nitrogen oxide sensor chip, calculate the actual resistance of heater head, further, remain 800 ℃ in order to the temperature value that guarantees heater chip through regulating the heating voltage value of well heater.

Said step a may further comprise the steps:

A1. at first calculate heater head resistance value Rh; Lead-in wire A that applies end at heater voltage and the free end of lead-in wire B be connected in series a variable power supply and a reometer; The free end of said potential electrode C connects a monitoring voltage table, and the other end of monitoring voltage table is connected between reometer and the variable power supply; Wherein variable power supply is used to well heater variable voltage V is provided, and reometer is used to monitor the current value I h of well heater, and the monitoring voltage table is used for the magnitude of voltage V1 at monitoring terminal two ends; The resistance value Rh of said heater head is according to computes:

Rh=（V－2V1）/Ih

A2., one thermopair is installed on the chip of nitrogen oxide sensor, is used to monitor the temperature value T of nitrogen oxide sensor chip;

A3. regulate the magnitude of voltage of variable power supply, V progressively increased progressively between 0 ~ 12V, the every change of magnitude of voltage once, synchronous recording V, V1, Ih and T; And according to following formula calculating heater head resistance value Rh;

A4. the numerical value that monitoring obtains according to step a3 is drawn the curve map between heater head actual resistance Rh and the nitrogen oxide sensor chip temperature T, and demarcates the temperature value T of nitrogen oxide sensor chip and the linear relationship of heater head resistance value Rh.

Variable power supply control method described in the step c is:

When nitrogen oxide sensor chip temperature during, draw heater head resistance R h greater than R according to step a4 greater than 800 ℃ ₈₀₀, reduce nitrogen oxide sensor heating voltage value V this moment, and the heating voltage value V ＇ after the reduction is according to computes:

V＇＝V ₈₀₀-Ｖ（Rh-R ₈₀₀）/R ₈₀₀

When nitrogen oxide sensor chip temperature value during, draw heater head resistance R h less than R according to step a4 less than 800 ℃ ₈₀₀, this moment the nitrogen oxide sensor heating voltage value V that raises, the heating voltage value V after the rising " according to computes:

V″＝V ₈₀₀+Ｖ（R ₈₀₀–Rh）/R ₈₀₀

The reduction value V ＇ or the lift-off value V of heating voltage " obtain through regulating variable power supply, remain 800 ℃ in order to the temperature value that guarantees heater chip.

Improvement of the present invention is: the head of said well heater adopts the dual damascene line structure; The wave molding live width that wherein is positioned under semiotic function layer first cavity is D1; The wave molding live width that is positioned under second cavity is D2; The wave molding live width at all the other positions is D3, and the ratio of said each section wave molding live width satisfies following formula:

$D1=\mathrm{<figure-callout\; id="2"\; label="D"\; filenames="HDA00002115556800013.png"\; state="\{\{state\}\}">D</figure-callout>}2=\frac{1}{2}D3.$

Owing to adopted above technical scheme, institute of the present invention acquisition of technology progress is following.

The present invention proposes a kind of new method for heating and controlling; At first the well heater of nitrogen oxide sensor is improved in this method and adopts three-way heating electrode structure; The temperature measurement electrode of in well heater, introducing is monitored the head resistance of nitrogen oxide sensor well heater constantly; In different exhaust temperature environment, apply the heating voltage of different time, different amplitudes to well heater, make the resistance value of heater head constant; Thereby make the temperature of nitrogen oxide sensor chip keep a definite value, improve the measuring accuracy of nitrogen oxide sensor NOx.

Description of drawings

Fig. 1 is the structural representation of three-wire type nitrogen oxide sensor well heater.

Fig. 2 is a nitrogen oxide sensor heater head resistance R h Calibration Circuit sketch.

Fig. 3 is nitrogen oxide sensor head resistance Rh and nitrogen oxide sensor head temperature T graph of a relation.

Embodiment

To combine specific embodiment and accompanying drawing below, the present invention will be further elaborated.

A kind of nitrogen oxide sensor method for heating and controlling; The well heater that said nitrogen oxide sensor comprises the semiotic function layer and is positioned at semiotic function layer below; Lead-in wire A and lead-in wire B that said well heater comprises heater head and connects the heater head two ends respectively; The voltage of well heater applies between the end side a and b and is provided with the potential electrode C that is used to gather the heater head resistance value, and the end of said potential electrode C is connected the junction of heater head and lead-in wire A or lead-in wire B.The temperature value that adopts the size of heater head resistance value to characterize nitrogen oxide sensor chip head in the method changes, and guarantees that through the magnitude of voltage that change is applied to the well heater two ends working temperature value of nitrogen oxide sensor chip is controlled at about 800 ℃.

The well heater of nitrogen oxide sensor adopts the three-wire type heater structure in the present invention, and the head of well heater adopts the dual damascene line structure, and is as shown in Figure 1.The wave molding live width that heater head is positioned under first cavity is D1; The wave molding live width that is positioned under second chamber is D2; All the other position wave molding live widths are D3.In order to make temperature in chip first cavity, second chamber can reach the temperature of galvanochemistry, catalytic reaction in each cavity, guarantee following relation between D1, D2, the D3:

$D1=\mathrm{<figure-callout\; id="2"\; label="D"\; filenames="HDA00002115556800013.png"\; state="\{\{state\}\}">D</figure-callout>}2=\frac{1}{2}D3.$

The wave molding live width is designed to D1=D2=1/2D3=0.3mm in the present embodiment.Adopt the mode of serigraphy heating electrode to be printed onto above the zirconia substrate resistance 0.8273 Ω between the AC behind the sintering; Resistance 4.231 Ω between the AB; The resistance value Rh=2.5765 Ω of heater head.

Method for heating and controlling described in the present embodiment is specific as follows said.

1) at first calculates heater head resistance value Rh.By circuit diagram shown in Figure 2; Lead-in wire A that applies end at heater voltage and the free end of lead-in wire B be connected in series a variable power supply and a reometer; The free end of potential electrode C connects a monitoring voltage table, and the other end of monitoring voltage table is connected between reometer and the variable power supply.Wherein variable power supply is used to well heater variable voltage V is provided, and reometer is used to monitor the current value I h of well heater, and the monitoring voltage table is used for the magnitude of voltage V1 at monitoring terminal two ends; The resistance value Rh of said heater head is according to computes:

Rh=(V-2V1)/Ih formula one

2) thermopair is installed on the chip of nitrogen oxide sensor, is used to monitor the temperature value T of nitrogen oxide sensor chip.

3) regulate the magnitude of voltage of variable power supply, V progressively increased progressively between 0 ~ 12V, the every change of magnitude of voltage once, synchronous recording V, V1, Ih and T; And according to formula one calculating heater head resistance value Rh; Monitoring and result of calculation are as shown in table 1:

Table 1

The voltage-regulation number of times	V/V	Vl/V	Ih/A	Rh/Ω	T/℃
						1	5.01	1.027	0.483	6.120	313
2	6.02	1.198	0.535	6.774	377
						3	7.03	1.364	0.589	7.304	429
4	8.01	1.534	0.629	7.857	507
						5	9.02	1.7	0.665	8.451	578
6	9.51	1.785	0.679	8.748	617
						7	10.03	1.896	0.683	9.133	670

8	10.54	1.994	0.698	9.387	704
						9	11.01	2.082	0.713	9.602	733
10	11.52	2.184	0.728	9.824	767
						11	12	2.279	0.742	10.030	795
12	12.5	2.379	0.761	10.173	824
						13	13.01	2.485	0.776	10.361	856
14	13.01	2.519	0.77	10.353	865

4) numerical value that monitoring obtains according to step 3) is drawn the curve map between heater head actual resistance Rh and the nitrogen oxide sensor chip temperature T, and is as shown in Figure 3.And the temperature value T of demarcation nitrogen oxide sensor chip and the relation of heater head resistance value Rh.The linear dependence that can draw Rh and T from curve map is 0.99372.

5) curve map of confirming according to step 4), when confirming that the nitrogen oxide sensor chip temperature is 800 ℃, the resistance value R of heater head ₈₀₀, the heating voltage of well heater is V ₈₀₀With resistance value R ₈₀₀With heating voltage V ₈₀₀As the calibration value of demarcating the nitrogen oxide sensor chip temperature.The linear fit straight-line equation that draws temperature value T and heater head resistance value Rh according to table 1 and Fig. 3 is:

T=130.67 * Rh-513.14 formula two

In the time of T=800 ℃, its Rh=10.049 Ω, i.e. R ₈₀₀=10.049 Ω.

6) according to the actual temperature value of detection nitrogen oxide sensor chip, the heating voltage value of regulating well heater remains 800 ℃ in order to the temperature value that guarantees heater chip.

The temperature of nitrogen oxide sensor chip derives from two parts, and a part is that tail gas transmits heat to chip, and the nitrogen oxide sensor chip temperature is raise, and this part is can not controlling factor; Another part is that nitrogen oxide sensor self well heater heats to chip, and chip temperature is raise, and this part can be through changing the heat that heating voltage V comes further control heater to transmit to chip.When exhaust temperature was too high, the nitrogen oxide sensor chip temperature calculated heater head resistance R h greater than calibration value 10.049 Ω greater than 800 ℃ according to formula two, and should reduce the heating voltage V at nitrogen oxide sensor well heater two ends this moment; Cross when low when exhaust temperature, nitrogen oxide sensor chip temperature value calculates heater head resistance R h less than R less than 800 ℃ according to formula two ₈₀₀, the heating voltage V at the nitrogen oxide sensor well heater two ends that should raise this moment.Measured value and calibration value R with Rh ₈₀₀Compare,, make the measured value of Rh remain calibration value R through adjustment heater voltage V ₈₀₀Thereby when nitrogen oxide sensor was worked under different tail gas environment, the temperature of nitrogen oxide sensor chip remained on constant 800 ℃.

During the nitrogen oxide sensor operate as normal, according to the magnitude of voltage and the current value of monitoring, calculate the actual value of heater head resistance value Rh, and it is compared with calibration value 10.049 Ω of heater head resistance.

As Rh＞R ₈₀₀The time, reducing nitrogen oxide sensor heating voltage value V, the heating voltage value V ＇ after the reduction is according to computes:

V＇＝V ₈₀₀-Ｖ（Rh-10.049Ω）/10.049Ω

As Rh＜R ₈₀₀The time, rising nitrogen oxide sensor heating voltage value V, the heating voltage value V after the rising " according to computes:

V″＝V ₈₀₀+Ｖ（10.049Ω-Rh)/10.049Ω

And according to the size of both deviates adjustment is applied to the heating voltage V on the nitrogen oxide sensor well heater; Nitrogen oxide sensor heater head resistance R h is equated with calibration value 10.049 Ω; Thereby make nitrogen oxide sensor in the process of operate as normal, the chip head resistance is all the time about 800 ℃.

Claims (4)

1. nitrogen oxide sensor method for heating and controlling; The well heater that said nitrogen oxide sensor comprises the semiotic function layer and is positioned at semiotic function layer below; Lead-in wire A and lead-in wire B that said well heater comprises heater head and connects the heater head two ends respectively; It is characterized in that: the voltage of said well heater applies and is provided with the potential electrode C that is used to gather the heater head resistance value between the end, and the end of said potential electrode C is connected the junction of heater head and lead-in wire A or lead-in wire B; Said method for heating and controlling is specially:

A. draw the temperature value T of nitrogen oxide sensor chip and the curve map between the heater head resistance value R;

When confirming that b. the nitrogen oxide sensor chip temperature is 800 ℃, the resistance calibration value R of heater head ₈₀₀, the heating voltage calibration value of well heater is V ₈₀₀

C. according to the actual temperature value of detection nitrogen oxide sensor chip, calculate the actual resistance of heater head, further, remain 800 ℃ in order to the temperature value that guarantees heater chip through regulating the heating voltage value of well heater.

2. nitrogen oxide sensor method for heating and controlling according to claim 1 is characterized in that said step a may further comprise the steps:

A1. at first calculate heater head resistance value Rh; Lead-in wire A that applies end at heater voltage and the free end of lead-in wire B be connected in series a variable power supply and a reometer; The free end of said potential electrode C connects a monitoring voltage table, and the other end of monitoring voltage table is connected between reometer and the variable power supply; Wherein variable power supply is used to well heater variable voltage V is provided, and reometer is used to monitor the current value I h of well heater, and the monitoring voltage table is used for the magnitude of voltage V1 at monitoring terminal two ends; The resistance value Rh of said heater head is according to computes:

Rh=（V－2V1）/Ih

A2., one thermopair is installed on the chip of nitrogen oxide sensor, is used to monitor the temperature value T of nitrogen oxide sensor chip;

A3. regulate the magnitude of voltage of variable power supply, V progressively increased progressively between 0 ~ 12V, the every change of magnitude of voltage once, synchronous recording V, V1, Ih and T; And according to following formula calculating heater head resistance value Rh;

A4. the numerical value that monitoring obtains according to step a3 is drawn the curve map between heater head actual resistance Rh and the nitrogen oxide sensor chip temperature T, and demarcates the temperature value T of nitrogen oxide sensor chip and the linear relationship of heater head resistance value Rh.

3. nitrogen oxide sensor method for heating and controlling according to claim 2 is characterized in that the variable power supply control method described in the step c is:

When nitrogen oxide sensor chip temperature during, draw heater head resistance R h greater than R according to step a4 greater than 800 ℃ ₈₀₀, reduce nitrogen oxide sensor heating voltage value V this moment, and the heating voltage value V ＇ after the reduction is according to computes:

V＇＝V ₈₀₀-Ｖ（Rh-R ₈₀₀）/R ₈₀₀

When nitrogen oxide sensor chip temperature value during, draw heater head resistance R h less than R according to step a4 less than 800 ℃ ₈₀₀, this moment the nitrogen oxide sensor heating voltage value V that raises, the heating voltage value V after the rising " according to computes:

V″＝V ₈₀₀+Ｖ（R ₈₀₀–Rh）/R ₈₀₀

The reduction value V ＇ or the lift-off value V of heating voltage " obtain through regulating variable power supply, remain 800 ℃ in order to the temperature value that guarantees heater chip.

4. according to each described nitrogen oxide sensor method for heating and controlling of claim 1 to 3; It is characterized in that: the head of said well heater adopts the dual damascene line structure; The wave molding live width that wherein is positioned under semiotic function layer first cavity is D1; The wave molding live width that is positioned under second cavity is D2, and the wave molding live width at all the other positions is D3, and the ratio of said each section wave molding live width satisfies following formula:

$D1=D2=\frac{1}{2}D3$

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