CN113250798B - Nitrogen-oxygen sensor - Google Patents
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- CN113250798B CN113250798B CN202110530149.0A CN202110530149A CN113250798B CN 113250798 B CN113250798 B CN 113250798B CN 202110530149 A CN202110530149 A CN 202110530149A CN 113250798 B CN113250798 B CN 113250798B
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
- F01N11/00—Monitoring or diagnostic devices for exhaust-gas treatment apparatus, e.g. for catalytic activity
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
- F01N11/00—Monitoring or diagnostic devices for exhaust-gas treatment apparatus, e.g. for catalytic activity
- F01N11/002—Monitoring or diagnostic devices for exhaust-gas treatment apparatus, e.g. for catalytic activity the diagnostic devices measuring or estimating temperature or pressure in, or downstream of the exhaust apparatus
- F01N11/005—Monitoring or diagnostic devices for exhaust-gas treatment apparatus, e.g. for catalytic activity the diagnostic devices measuring or estimating temperature or pressure in, or downstream of the exhaust apparatus the temperature or pressure being estimated, e.g. by means of a theoretical model
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
- F01N11/00—Monitoring or diagnostic devices for exhaust-gas treatment apparatus, e.g. for catalytic activity
- F01N11/007—Monitoring or diagnostic devices for exhaust-gas treatment apparatus, e.g. for catalytic activity the diagnostic devices measuring oxygen or air concentration downstream of the exhaust apparatus
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
- F01N13/00—Exhaust or silencing apparatus characterised by constructional features ; Exhaust or silencing apparatus, or parts thereof, having pertinent characteristics not provided for in, or of interest apart from, groups F01N1/00 - F01N5/00, F01N9/00, F01N11/00
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
- F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
- F01N3/08—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous
- F01N3/10—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust
- F01N3/18—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust characterised by methods of operation; Control
- F01N3/20—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust characterised by methods of operation; Control specially adapted for catalytic conversion ; Methods of operation or control of catalytic converters
- F01N3/2066—Selective catalytic reduction [SCR]
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01K—MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR
- G01K7/00—Measuring temperature based on the use of electric or magnetic elements directly sensitive to heat ; Power supply therefor, e.g. using thermoelectric elements
- G01K7/16—Measuring temperature based on the use of electric or magnetic elements directly sensitive to heat ; Power supply therefor, e.g. using thermoelectric elements using resistive elements
- G01K7/18—Measuring temperature based on the use of electric or magnetic elements directly sensitive to heat ; Power supply therefor, e.g. using thermoelectric elements using resistive elements the element being a linear resistance, e.g. platinum resistance thermometer
- G01K7/20—Measuring temperature based on the use of electric or magnetic elements directly sensitive to heat ; Power supply therefor, e.g. using thermoelectric elements using resistive elements the element being a linear resistance, e.g. platinum resistance thermometer in a specially-adapted circuit, e.g. bridge circuit
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
- G01N27/26—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating electrochemical variables; by using electrolysis or electrophoresis
- G01N27/403—Cells and electrode assemblies
- G01N27/406—Cells and probes with solid electrolytes
- G01N27/407—Cells and probes with solid electrolytes for investigating or analysing gases
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
- Y02T10/00—Road transport of goods or passengers
- Y02T10/10—Internal combustion engine [ICE] based vehicles
- Y02T10/12—Improving ICE efficiencies
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
- Y02T10/00—Road transport of goods or passengers
- Y02T10/10—Internal combustion engine [ICE] based vehicles
- Y02T10/40—Engine management systems
Abstract
The invention provides a nitrogen-oxygen sensor, and relates to the technical field of sensors. The nitrogen-oxygen sensor comprises a probe and a controller, wherein a platinum heating wire is arranged in the probe, and the probe is connected with the controller through a wire harness; when the nitrogen-oxygen sensor works, the probe is heated by the platinum heating wire, the resistance value of the platinum heating wire is equal to the preset value, in the exhaust temperature change process around the probe, the heating circuit of the controller keeps the resistance value of the platinum heating wire constant to be the preset value by adjusting the heating voltage or the heating current of the platinum heating wire, and the controller calculates and determines the real-time exhaust temperature around the probe according to the real-time heating voltage or the real-time heating current corresponding to the two ends of the platinum heating wire. Compared with the prior art, two temperature sensors are saved in a urea injection system, and the cost is greatly saved.
Description
Technical Field
The invention relates to the technical field of sensors, in particular to a nitrogen-oxygen sensor.
Background
In engine exhaust emission, toxic gases contain nitrogen and oxygen, and in order to detect and control the amount of nitrogen and oxygen emitted, two nitrogen and oxygen sensors are generally disposed on an exhaust emission pipeline. The front nitrogen-oxygen sensor is used for measuring the concentration of nitrogen-oxygen gas, and an SCR (urea injection system) feeds back a concentration value signal and the exhaust temperature of tail gas to a CAN (controller area network) communication system of a vehicle, so that the urea injection system forms accurate injection quantity, and the emission quantity of nitrogen and oxygen is controlled in a closed loop manner; in addition, the OBD diagnostic system can judge the qualification of emission according to the nitrogen oxygen signal output by the rear nitrogen oxygen sensor.
However, conventional NOx sensors can only measure NOx and oxygen concentration values and cannot measure exhaust gas temperatures. In order to obtain the exhaust gas temperature, a temperature sensor needs to be arranged for each of the front and rear nitrogen-oxygen sensors, which greatly increases the cost of the SCR.
Disclosure of Invention
The present invention is directed to provide a nox sensor to solve the problem of measuring the exhaust temperature by using a nox sensor, which overcomes the above-mentioned shortcomings of the prior art.
In order to achieve the purpose, the technical scheme adopted by the invention is as follows:
the invention provides a nitrogen-oxygen sensor, which comprises a probe and a controller, wherein the probe is a zirconia ceramic probe, a platinum heating wire is arranged in the probe, and the probe is connected with the controller through a wire harness;
when the nitrogen-oxygen sensor works, the probe is heated by the platinum heating wire, the resistance value of the platinum heating wire is equal to the preset value, in the exhaust temperature change process around the probe, the heating circuit of the controller keeps the resistance value of the platinum heating wire constant to be the preset value by adjusting the heating voltage or the heating current of the platinum heating wire, and the controller calculates and determines the real-time exhaust temperature around the probe according to the real-time heating voltage or the real-time heating current corresponding to the two ends of the platinum heating wire.
Optionally, the Rh detection circuit of the controller is utilized to obtain the resistance value of the platinum heating wire through the voltage detection feedback of the internal circuit, the preset value is 10.065 ohms, and in the case that the preset value is 10.065 ohms, the working temperature of the probe is 800 ℃.
Optionally, according to the acquired resistance value of the platinum heating wire, the heating circuit of the controller adjusts the heating voltage of the platinum heating wire through pulse width modulation so that the resistance value of the platinum heating wire is kept constant at a preset value, and the controller calculates and determines the real-time exhaust temperature around the probe according to the corresponding real-time heating voltage at two ends of the platinum heating wire.
Optionally, the heating voltage V of the platinum heating wire and the voltage pulse duty ratio x applied by the heating circuit satisfy the following linear relationship: v-11.985 x-0.006.
Optionally, the temperature T of the platinum heating wire and the heating voltage V of the platinum heating wire satisfy the following relationship: t ═ 7.5V3+137.11V2-708.09V+1560.12。
Optionally, when the nitrogen-oxygen sensor detects that the oxygen content in the exhaust gas around the probe is equal to a specified value, the exhaust gas temperature is changed to obtain the voltage pulse duty ratio of the corresponding heating voltage at different exhaust gas temperatures, so as to obtain the relationship between the exhaust gas temperature and the voltage pulse duty ratio in a numerical fitting manner.
Alternatively, in the case where the specified value is 4%, the relationship between the exhaust gas temperature and the voltage pulse duty ratio satisfies the following expression:
y＝-4949.2x2+114923x-725474, where x represents the voltage pulse duty cycle and y represents the exhaust temperature.
Alternatively, in the case where the specified value is 16%, the relationship between the exhaust gas temperature and the voltage pulse duty ratio satisfies the following expression:
y＝-4239.5x2+108428x-692966, where x represents the voltage pulse duty cycle and y represents the exhaust temperature.
Alternatively, the controller is connected to a CAN bus of a vehicle mounted with the nitrogen oxygen sensor, and the controller calculates the exhaust temperature in real time according to the applied voltage pulse duty ratio and the relationship between the exhaust temperature and the voltage pulse duty ratio, and feeds back the exhaust temperature to the CAN bus.
Optionally, a urea injection system of the vehicle is connected to the CAN bus, and the urea injection system obtains the exhaust temperature through the CAN bus.
The beneficial effects of the invention include:
the nitrogen-oxygen sensor provided by the invention comprises a probe and a controller, wherein the probe is a zirconia ceramic probe, a platinum heating wire is arranged in the probe, and the probe is connected with the controller through a wire harness; when the nitrogen-oxygen sensor works, the probe is heated by the platinum heating wire, the resistance value of the platinum heating wire is equal to the preset value, in the exhaust temperature change process around the probe, the heating circuit of the controller keeps the resistance value of the platinum heating wire constant to be the preset value by adjusting the heating voltage or the heating current of the platinum heating wire, and the controller calculates and determines the real-time exhaust temperature around the probe according to the real-time heating voltage or the real-time heating current corresponding to the two ends of the platinum heating wire. By utilizing the resistance characteristic of the platinum heating wire in the ceramic probe of the nitrogen-oxygen sensor and reversely pushing the numerical value of the ambient temperature (exhaust temperature) in the nitrogen-oxygen sensor controller through monitoring the heating control data, compared with the prior art, two temperature sensors are saved in a urea injection system, and the cost is greatly saved.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed for the embodiments or the prior art descriptions will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings without creative efforts.
FIG. 1 is a schematic diagram illustrating a structure of a nitrogen oxide sensor provided by an embodiment of the invention;
FIG. 2 is a schematic structural diagram of a zirconia ceramic probe provided by an embodiment of the present invention;
FIG. 3 is a graph showing the relationship between the sensor temperature and the resistance value of a platinum heating wire of the nitrogen oxide sensor provided by the embodiment of the invention;
FIG. 4 is a graph showing a relationship between a sensor temperature of a nitrogen oxide sensor and a heating voltage of a platinum heating wire according to an embodiment of the present invention;
fig. 5A and 5B respectively show the relationship between the exhaust gas temperature measured at different oxygen concentrations and the heating voltage PWM of the platinum heating wire of the nitrogen oxygen sensor provided by the embodiment of the invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
In engine exhaust emission, toxic gases contain nitrogen and oxygen, and in order to detect and control the amount of nitrogen and oxygen emitted, two nitrogen and oxygen sensors are generally disposed on an exhaust emission pipeline. The front nitrogen-oxygen sensor is used for measuring the concentration of nitrogen-oxygen gas, and an SCR (urea injection system) feeds back a concentration value signal and the exhaust temperature of tail gas to a CAN (controller area network) communication system of a vehicle, so that the urea injection system forms accurate injection quantity, and the emission quantity of nitrogen and oxygen is controlled in a closed loop manner; in addition, the OBD diagnostic system can judge the qualification of emission according to the nitrogen oxygen signal output by the rear nitrogen oxygen sensor.
However, conventional NOx sensors can only measure NOx and oxygen concentration values and cannot measure exhaust gas temperatures. In order to obtain the exhaust gas temperature, a temperature sensor needs to be arranged for each of the front and rear nitrogen-oxygen sensors, which greatly increases the cost of the SCR. To this end, the present invention provides a nitrogen oxygen sensor capable of measuring the temperature of exhaust gas.
Fig. 1 shows a schematic structural diagram of a nitrogen oxide sensor provided by an embodiment of the invention. As shown in FIG. 1, the nitrogen-oxygen sensor comprises a probe 101 and a controller 102, wherein the probe 101 is a zirconia ceramic probe, a platinum heating wire is arranged in the probe 101, and the probe 101 is connected with the controller 102 through a wire harness 103. The controller 102 includes a socket connector 121 and a socket connector 122. The connector 121 is connected to the wire harness 103, and the connector 122 is connected to the CAN bus.
Fig. 2 shows a schematic structural diagram of a zirconia ceramic probe provided by an embodiment of the present invention. As shown in fig. 2, the zirconia ceramic probe includes a first zirconia ceramic layer 201, a second zirconia ceramic layer 202, a third zirconia ceramic layer 203, a fourth zirconia ceramic layer 204, a fifth zirconia ceramic layer 205, and a sixth zirconia ceramic layer 206, which are sequentially stacked from top to bottom, the second zirconia ceramic layer 202 has a first chamber 207 and a second chamber 208 formed therein, an air passage 209 is formed on the right side of the fourth zirconia ceramic layer 204, and a platinum heater wire 210 is provided between the fifth zirconia ceramic layer 205 and the sixth zirconia ceramic layer 206. A first pumping oxygen positive electrode 211 and a first pumping oxygen negative electrode 212 are disposed on the upper side of the first chamber 207, a second pumping oxygen negative electrode 213 is disposed on the upper side of the second chamber 208, a measuring electrode 214 is disposed on the lower side of the second chamber 208, and a reference electrode 215 is disposed on the upper side of the air passage 209. A first diffusion channel 216 is provided at the left side of the first chamber 207, and a second diffusion channel 217 is provided between the first chamber 207 and the second chamber 208.
When the nitrogen-oxygen sensor works, the probe is heated by the platinum heating wire 210, the resistance value of the platinum heating wire 210 is equal to the preset value, in the exhaust temperature change process around the probe, the heating circuit of the controller maintains the constant resistance value of the platinum heating wire as the preset value by adjusting the heating voltage or the heating current of the platinum heating wire 210, and the controller calculates and determines the real-time exhaust temperature around the probe according to the real-time heating voltage or the real-time heating current corresponding to the two ends of the platinum heating wire 210.
To sum up, utilize the resistance characteristic of platinum heater strip in the nitrogen oxygen sensor ceramic probe, reverse the numerical value of ambient temperature (exhaust temperature) through control heating data in the nitrogen oxygen sensor controller, compare with prior art, saved two temperature sensor in urea injection system, practiced thrift the cost greatly.
Optionally, the Rh detection circuit of the controller is utilized to obtain the resistance value of the platinum heating wire through the voltage detection feedback of the internal circuit, the preset value is 10.065 ohms, and in the case that the preset value is 10.065 ohms, the working temperature of the probe is 800 ℃. Optionally, according to the acquired resistance value of the platinum heating wire, the heating circuit of the controller adjusts the heating voltage of the platinum heating wire through pulse width modulation so that the resistance value of the platinum heating wire is kept constant at a preset value, and the controller calculates and determines the real-time exhaust temperature around the probe according to the corresponding real-time heating voltage at two ends of the platinum heating wire. Optionally, the heating voltage V of the platinum heating wire and the voltage pulse duty ratio x applied by the heating circuit satisfy the following linear relationship: v-11.985 x-0.006. Optionally, the temperature T of the platinum heating wire and the heating voltage V of the platinum heating wire satisfy the following relationship: t ═ 7.5V3+137.11V2-708.09V + 1560.12. Optionally, when the nitrogen-oxygen sensor detects that the oxygen content in the exhaust gas around the probe is equal to a specified value, the exhaust gas temperature is changed to obtain the voltage pulse duty ratio of the corresponding heating voltage at different exhaust gas temperatures, so as to obtain the relationship between the exhaust gas temperature and the voltage pulse duty ratio in a numerical fitting manner.
Alternatively, in the case where the specified value is 4%, the relationship between the exhaust gas temperature and the voltage pulse duty ratio satisfies the following expression: -4949.2x2+114923x-725474, where x represents the voltage pulse duty cycle and y represents the exhaust temperature. Alternatively, in the case where the specified value is 16%, the relationship between the exhaust gas temperature and the voltage pulse duty ratio satisfies the following expression: -4239.5x2+108428x-692966, where x represents the voltage pulse duty cycle and y represents the exhaust temperature. Alternatively, the controller is connected to a CAN bus of a vehicle mounted with the nitrogen oxygen sensor, and the controller calculates the exhaust temperature in real time according to the applied voltage pulse duty ratio and the relationship between the exhaust temperature and the voltage pulse duty ratio, and feeds back the exhaust temperature to the CAN bus. Optionally, a urea injection system of the vehicle is connected to the CAN bus, and the urea injection system obtains the exhaust temperature through the CAN bus.
FIG. 3 is a graph showing the relationship between the sensor temperature and the resistance value of a platinum heating wire of the nitrogen oxide sensor provided by the embodiment of the invention; FIG. 4 is a graph showing a relationship between a sensor temperature of a nitrogen oxide sensor and a heating voltage of a platinum heating wire according to an embodiment of the present invention; fig. 5A and 5B respectively show the relationship between the exhaust gas temperature measured at different oxygen concentrations and the heating voltage PWM of the platinum heating wire of the nitrogen oxygen sensor provided by the embodiment of the invention. The principle of the nitrogen oxide sensor for measuring temperature according to the embodiment of the present invention will be described in detail with reference to fig. 3, 4, 5A and 5B.
The ceramic probe of the nitrogen-oxygen sensor is internally provided with a platinum heating wire which is used for controlling the working temperature of the ceramic piece to be 800 ℃ and keeping the activity, and the resistance of the platinum heating wire has a good linear relation with the temperature (as shown in figure 3). The heating power is formed by applying voltage to the platinum heating wire, so that the sensor probe is at 800 degrees, and the platinum resistance value Rh is 10.065 ohms (Rh is fed back through voltage detection of an internal circuit of the controller) and is kept constant. As shown in fig. 4, as the ambient exhaust gas temperature is constantly changing, the voltage needs to be constantly adjusted to maintain a constant Rh of 10.065 ohms, with the controller regulating the heating circuit and Rh detection circuit via PWM (pulse width modulation). The controller is based on measuring the electricity across the platinum resistorThe pressure signal is used for judging the ambient gas temperature information, and the PWM adjusts the voltage through the duty ratio of the square wave sequence signal, so that the sensor is constantly adjusted to be at a certain working temperature (for example 800 degrees). The temperature of the heating wire and the platinum resistance voltage and the duty cycle are numerically related, for example, in fig. 4, the temperature of the heating wire and the platinum resistance voltage conform to a cubic polynomial characteristic T of-7.5V3+137.11V2708.09V +1560.12, while the software controls the readout voltage and duty cycle x to conform to a linear relationship (e.g., 11.985x-0.006 is measured in practical embodiments); in the experiment, the relation between the temperature TEMP of different environment gases and the duty ratio is obtained by measuring the temperature TEMP of the different environment gases and is stored in software (as shown in a figure 5A and a figure 5B), and during the working period of the nitrogen oxygen sensor, the exhaust temperature y of the environment gases at proper time is calculated according to the duty ratio x in the formula and then is fed back to the CAN bus. In the embodiment of the present application, only the PWM control mode is listed, and it should be understood that in practical application, the direct current can be adjusted to control the temperature of the heating wire of the ceramic probe.
In the invention, the exhaust temperature data obtained by the nitrogen oxygen sensor provided by the invention is output to a CAN bus, and the SCR reads signals of the CAN bus to obtain the exhaust temperature data.
In summary, the resistance characteristic of the platinum heating wire in the ceramic probe of the nox sensor is utilized, and the controller monitors the control data of the temperature control module (feedback voltage of the platinum resistance of the heating wire, or PWM duty ratio or dc power-up module), so as to reverse the temperature of the exhaust gas around the nox sensor. The temperature of the exhaust gas around the nitrogen-oxygen sensor is provided by the nitrogen-oxygen sensor and is transmitted to the CAN bus through the nitrogen-oxygen sensor controller, so that an injection basis is provided for SCR. The nitrogen-oxygen sensor provided by the invention can measure the concentration value of nitrogen-oxygen gas and simultaneously measure the exhaust temperature around the nitrogen-oxygen sensor, thereby saving two temperature sensors for users, greatly saving the cost and saving the installation space of parts.
The above embodiments are merely illustrative of the technical concept and features of the present invention, and the purpose thereof is to enable those skilled in the art to understand the content of the present invention and implement the present invention, and not to limit the scope of the present invention, and all equivalent changes or modifications made according to the spirit of the present invention should be covered in the scope of the present invention.
Claims (7)
1. The nitrogen-oxygen sensor is characterized by comprising a probe and a controller, wherein the probe is a zirconia ceramic probe, a platinum heating wire is arranged in the probe, and the probe is connected with the controller through a wire harness;
when the nitrogen-oxygen sensor works, the probe is heated through the platinum heating wire, the resistance value of the platinum heating wire is equal to a preset value, in the exhaust temperature change process around the probe, a heating circuit of the controller enables the resistance value of the platinum heating wire to be kept constant at the preset value by adjusting the heating voltage or the heating current of the platinum heating wire, and the controller calculates and determines the real-time exhaust temperature around the probe according to the real-time heating voltage or the real-time heating current corresponding to two ends of the platinum heating wire;
acquiring the resistance value of the platinum heating wire by using an Rh detection circuit of the controller through voltage detection feedback of an internal circuit, wherein the preset value is 10.065 ohms, and the working temperature of the probe is 800 ℃ under the condition that the preset value is 10.065 ohms;
according to the acquired resistance value of the platinum heating wire, a heating circuit of the controller adjusts the heating voltage of the platinum heating wire through pulse width modulation so as to keep the resistance value of the platinum heating wire constant at the preset value, and the controller calculates and determines the real-time exhaust temperature around the probe according to the corresponding real-time heating voltage at the two ends of the platinum heating wire;
when the nitrogen-oxygen sensor detects that the oxygen content in the exhaust gas around the probe is equal to a specified value, the exhaust temperature is changed to obtain the voltage pulse duty ratio of the corresponding heating voltage at different exhaust temperatures, so that the relationship between the exhaust temperature and the voltage pulse duty ratio is obtained in a numerical fitting manner;
the controller calculates the exhaust temperature in real time according to the applied voltage pulse duty cycle and the relationship between the exhaust temperature and the voltage pulse duty cycle.
2. The nitroxide sensor of claim 1, wherein the following linear relationship is satisfied between the heating voltage V of the platinum heating wire and the voltage pulse duty ratio x applied by the heating circuit: v =11.985 x-0.006.
3. The nitrogen oxygen sensor according to claim 2, wherein the temperature T of the platinum heating wire and the heating voltage V of the platinum heating wire satisfy the following relationship: t = -7.5V3+137.11V2-708.09V+1560.12。
4. The nitrogen oxygen sensor according to claim 1, wherein in the case where the specified value is 4%, a relationship between an exhaust gas temperature and a voltage pulse duty ratio satisfies the following expression:
y=-4949.2x2+114923x-725474, where x represents the voltage pulse duty cycle and y represents the exhaust temperature.
5. The nitrogen oxygen sensor according to claim 1, wherein in the case where the specified value is 16%, a relationship between an exhaust gas temperature and a voltage pulse duty ratio satisfies the following expression:
y=-4239.5x2+108428x-692966, where x represents the voltage pulse duty cycle and y represents the exhaust temperature.
6. The NOx sensor of claim 1 wherein the controller is connected to a CAN bus of a vehicle on which the NOx sensor is mounted and the controller feeds the exhaust temperature back to the CAN bus.
7. The NOx sensor of claim 6, wherein a urea injection system of the vehicle is coupled to the CAN bus, the urea injection system obtaining the exhaust temperature via the CAN bus.
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| JP3332761B2 (en) * | 1996-11-08 | 2002-10-07 | 日本特殊陶業株式会社 | Oxygen concentration / nitrogen oxide concentration measurement method and device |
| CN102798654B (en) * | 2012-09-08 | 2014-08-06 | 无锡隆盛科技股份有限公司 | Heating control method for nitrogen oxygen sensor |
| CN104932583B (en) * | 2015-04-30 | 2017-02-22 | 湖北丹瑞新材料科技有限公司 | Nitrogen oxygen sensor heating detection apparatus and control method thereof |
| CN105892529B (en) * | 2016-06-12 | 2018-06-12 | 上海感先汽车传感器有限公司 | A kind of nitrogen oxide sensor heating control circuit and method |
| CN207007767U (en) * | 2017-07-27 | 2018-02-13 | 深圳安培龙科技股份有限公司 | A kind of new-type nitrogen oxide sensor |
| CN110907522A (en) * | 2019-12-03 | 2020-03-24 | 湖北丹瑞新材料科技有限公司 | Method for improving measurement precision of nitrogen-oxygen sensor |
| CN111751494A (en) * | 2020-05-22 | 2020-10-09 | 蚌埠煜明电子科技有限公司 | Detection apparatus for nitrogen oxygen sensor |
| CN112526066B (en) * | 2020-11-20 | 2022-09-13 | 深圳市森世泰科技有限公司 | Gas concentration measuring device and method |
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