A nitrogen-oxygen sensor, a nitrogen-oxygen sensor control system, and a method of measuring nitrogen-oxygen
By optimizing the electrode combination and double diffusion barrier structure of the nitrogen and oxygen sensor, the problems of insufficient measurement accuracy, anti-interference ability and high temperature stability of traditional nitrogen and oxygen sensors have been solved, achieving higher measurement accuracy, lower manufacturing cost and longer service life.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- SHENZHEN SENSOR TECH CO LTD
- Filing Date
- 2026-04-10
- Publication Date
- 2026-07-07
AI Technical Summary
Existing nitrogen and oxygen sensors are inadequate in terms of measurement accuracy, anti-interference ability, and high-temperature stability, making it difficult to meet increasingly stringent emission regulations, and they are also costly to manufacture.
A functional electrode group consisting of an oxygen electrode unit, a reference electrode unit, a nitrogen oxide electrode unit, and a common electrode unit is adopted. Combined with a double diffusion barrier structure and a heater, the sensor structure is simplified, and the risk of signal coupling is reduced by graded processing of oxygen and nitrogen oxides in the gas.
It improves measurement accuracy and anti-interference ability, enhances high-temperature stability, reduces manufacturing costs, extends service life, and has better resistance to poisoning and high-temperature performance.
Smart Images
Figure CN122345648A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of gas sensing and measurement technology, and in particular to a nitrogen and oxygen sensor, a nitrogen and oxygen sensing and control system, and a method for measuring nitrogen and oxygen. Background Technology
[0002] With the rapid development of the global automotive industry and the increasing awareness of environmental protection, various countries have successively introduced stringent emission regulations for motor vehicles and non-road mobile machinery (such as China's National VI standard, the EU's Euro VI standard, and the US EPA Tier 3 standard), which impose extremely strict requirements on the emission limits of nitrogen oxides (NOx, mainly including NO and NO2). As the core sensing component of the exhaust aftertreatment system, the nitrogen oxide sensor's measurement accuracy, response speed, anti-interference ability, and stability directly determine the purification efficiency of the aftertreatment system.
[0003] Currently, traditional nitrogen oxide sensors on the market consist of a main oxygen electrode unit, an auxiliary oxygen electrode unit, a NOx electrode unit, a reference electrode unit, a common electrode unit, and three heater electrodes. These sensors have the following technical defects in practical applications: (1) The measurement accuracy is easily affected by interfering gases in the exhaust gas (such as CO, HC, SO2). SO2 can react with the sensor's sensitive material, causing the sensor to be "poisoned" and the measurement accuracy to decrease after long-term use; (2) Under the temperature conditions of drastic fluctuations in the exhaust pipe of motor vehicles (-40℃~900℃), the sensor's sensitive material is prone to performance degradation under long-term high temperature and alternating hot and cold conditions, resulting in poor high-temperature stability and short service life; (3) The precision preparation of multiple electrodes, circuit layout, and packaging processes are highly complex, resulting in high manufacturing costs.
[0004] Although various improvements have been made to address the aforementioned issues in existing technologies, problems such as high signal coupling risk, limited measurement accuracy, and insufficient anti-interference capability still exist, making it difficult to meet increasingly stringent emission regulations.
[0005] The above background information is provided only to aid in understanding the concept and technical solution of this invention. It does not necessarily belong to the prior art of this patent application. In the absence of clear evidence that the above information was disclosed on the filing date of this patent application, the above background information should not be used to evaluate the novelty and inventiveness of this application. Summary of the Invention
[0006] To address the aforementioned technical problems, this invention proposes a nitrogen-oxygen sensor, a nitrogen-oxygen sensing and control system, and a method for measuring nitrogen and oxygen. While simplifying the sensor structure and reducing manufacturing costs, it also improves the measurement accuracy, anti-interference ability, and high-temperature stability of oxygen and nitrogen oxide concentrations.
[0007] To achieve the above objectives, the present invention adopts the following technical solution: In a first aspect, the present invention discloses a nitrogen and oxygen sensor, comprising: The sensor element is made of an ion-conductive material. The sensor element has a gas diffusion path inside, and a first diffusion barrier and a second diffusion barrier are arranged sequentially on the gas diffusion path. A functional electrode assembly is disposed on the sensor element and is at least partially located on the gas diffusion path; A heater, integrated on the sensor element, is used to heat the sensor element; The functional electrode assembly includes an oxygen electrode unit, a reference electrode unit, a nitrogen oxide electrode unit, and a common electrode unit. The oxygen electrode unit is used to pump oxygen and generate a first current signal positively correlated with the oxygen concentration. The reference electrode unit is used to detect the oxygen partial pressure. The nitrogen oxide electrode unit is used to decompose nitrogen oxides and generate a second current signal positively correlated with the nitrogen oxide concentration. The common electrode unit is electrically connected to the oxygen electrode unit, the reference electrode unit, and the nitrogen oxide electrode unit to form a common potential loop.
[0008] Preferably, the oxygen electrode unit includes a first electrode portion and a second electrode portion, the first electrode portion being disposed outside the gas diffusion path, and the second electrode portion being disposed in a first chamber located between the first diffusion barrier and the second diffusion barrier on the gas diffusion path, and the second electrode portion being an electrode made of a material that inhibits the decomposition of nitrogen oxides.
[0009] Preferably, the reference electrode unit includes a third electrode portion and a fourth electrode portion. The third electrode portion is disposed in a first chamber located between the first diffusion barrier and the second diffusion barrier on the gas diffusion path. The third electrode portion is electrically connected to the oxygen electrode unit to provide an oxygen partial pressure reference signal. The fourth electrode portion is disposed in a second chamber located after the second diffusion barrier on the gas diffusion path, and the fourth electrode portion is used to provide a potential reference.
[0010] Preferably, the nitrogen oxide electrode unit includes a fifth electrode portion and a sixth electrode portion, which are respectively disposed in a second chamber located after the second diffusion barrier on the gas diffusion path. The fifth electrode portion is electrically connected to the common electrode unit for decomposing nitrogen oxides.
[0011] Secondly, the present invention discloses a nitrogen oxide sensing and control system, comprising: The nitrogen and oxygen sensor described in the first aspect; The processor is electrically connected to the functional electrode group and the heater; The processor is configured to: control the operating state of the heater to maintain the sensor element at a predetermined operating temperature; apply a first voltage to the oxygen electrode unit to regulate the oxygen partial pressure of the gas entering through the first diffusion barrier, and acquire the first current signal generated by the oxygen electrode unit; apply a second voltage to the nitrogen oxide electrode unit to decompose nitrogen oxides in the gas entering through the second diffusion barrier, and acquire the second current signal generated by the nitrogen oxide electrode unit; and determine the oxygen concentration and nitrogen oxide concentration based on the first current signal and the second current signal.
[0012] Preferably, the processor is further configured to: acquire a voltage signal representing the oxygen partial pressure generated by the reference electrode unit, and adjust the first voltage based on the difference between the voltage signal and the target value, so as to stabilize the oxygen partial pressure in the first chamber between the first diffusion barrier and the second diffusion barrier within the target range.
[0013] Preferably, the nitrogen oxide sensing and control system further includes an analog-to-digital conversion unit and a communication unit. The analog-to-digital conversion unit is connected between the functional electrode group and the processor and is used to convert the current signal generated by the functional electrode group into a digital signal. The communication unit is connected to the output terminal of the processor and is used to output the oxygen concentration and nitrogen oxide concentration in the gas.
[0014] Thirdly, the present invention discloses a method for measuring nitrogen and oxygen using the nitrogen and oxygen sensor described in the first aspect, comprising the following steps: The operating state of the heater is controlled to maintain the sensor element at a predetermined operating temperature; A first voltage is applied to the oxygen electrode unit to regulate the oxygen partial pressure of the gas entering through the first diffusion barrier, and the first current signal generated by the oxygen electrode unit is acquired. A second voltage is applied to the nitrogen oxide electrode unit to decompose nitrogen oxides in the gas that enters through the second diffusion barrier, and a second current signal generated by the nitrogen oxide electrode unit is acquired. The oxygen concentration and nitrogen oxide concentration in the gas are determined based on the first current signal and the second current signal.
[0015] Preferably, the method for measuring nitrogen and oxygen further includes: acquiring a voltage signal characterizing the oxygen partial pressure generated by the reference electrode unit, and adjusting the first voltage based on the difference between the voltage signal and the target value, so as to stabilize the oxygen partial pressure in the first chamber between the first diffusion barrier and the second diffusion barrier within the target range.
[0016] Preferably, when controlling the operating state of the heater, the sensor element is determined to have reached the predetermined operating temperature by monitoring the internal resistance of the reference electrode unit.
[0017] Compared with existing technologies, the advantages of this invention are as follows: This invention constructs an integrated sensing and measurement system by employing a functional electrode group comprising an oxygen electrode unit, a reference electrode unit, a nitrogen oxide electrode unit, and a common electrode unit, and by having it work in conjunction with a gas diffusion path equipped with first and second diffusion barriers and a heater. This design unifies the potential loop through the common electrode unit, simplifies the internal structure and circuit connections of the sensor, and reduces manufacturing costs and signal coupling risks. Simultaneously, the coordinated configuration of the double diffusion barrier structure and each electrode unit enables staged gas processing during measurement. First, the oxygen partial pressure is precisely controlled and nitrogen oxide decomposition is suppressed in the first chamber, and then nitrogen oxides are specifically decomposed and measured in the second chamber, thereby significantly reducing mutual interference during the measurement process. This systematic design ultimately achieves simultaneous improvements in measurement accuracy, anti-interference capability, and high-temperature stability while simplifying the structure and reducing costs.
[0018] In a further embodiment, the precise control of the heater by the processor and the acquisition and processing of signals from each electrode enable accurate measurement of oxygen and nitrogen oxide concentrations; the digital processing and output of signals are achieved through the analog-to-digital conversion unit and the communication unit, thereby improving the system's compatibility and reliability.
[0019] Other beneficial effects of the embodiments of the present invention will be further described below. Attached Figure Description
[0020] Figure 1 This is a schematic diagram of the structure of the nitrogen and oxygen sensor in Embodiment 1 of the present invention; Figure 2 This is a schematic diagram of the nitrogen and oxygen sensing control system in Embodiment 2 of the present invention; Figure 3a This is a schematic diagram showing that the current and oxygen value of the oxygen electrode unit in this embodiment of the invention are positively correlated; Figure 3b This is a schematic diagram showing a positive correlation between the current and the nitrogen oxide value of the nitrogen oxide electrode unit in an embodiment of the present invention. Detailed Implementation
[0021] The embodiments of the present invention will be described in detail below. It should be emphasized that the following description is merely exemplary and not intended to limit the scope and application of the present invention.
[0022] It should be noted that when a component is referred to as "fixed to" or "set on" another component, it can be directly on or indirectly on that other component. When a component is referred to as "connected to" another component, it can be directly connected to or indirectly connected to that other component. Furthermore, a connection can be used for both fixing and circuit / signal connectivity.
[0023] It should be understood that the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", and "outer" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the present invention.
[0024] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of embodiments of the present invention, "a plurality of" means two or more, unless otherwise explicitly specified.
[0025] This invention is based on the principle of electrochemical measurement. By optimizing the sensor electrode structure and control system, it reduces the number of electrodes, lowers the risk of signal coupling, and improves measurement accuracy and stability. Its core lies in optimizing the layout and functional allocation of the functional electrode group (composed of an oxygen electrode unit, a reference electrode unit, a nitrogen oxide electrode unit, and a common electrode unit), combined with a double diffusion barrier structure, to achieve accurate and interference-resistant measurement of the concentrations of oxygen and nitrogen oxides in a gas. The design of the common electrode unit simplifies the circuitry, and the heater ensures the sensor's optimal operating temperature.
[0026] The embodiments of this invention aim to provide a nitrogen and oxygen sensor with a simplified structure and higher accuracy. For example... Figure 1As shown, Embodiment 1 of the present invention discloses a nitrogen-oxygen sensor 100, including a sensor element 10, a functional electrode group, and a heater 30. The sensor element 10 is made of an ion-conductive material, wherein the sensor element 10 has a gas diffusion path inside, and a first diffusion barrier 11 and a second diffusion barrier 12 are sequentially arranged on the gas diffusion path. The functional electrode group is disposed on the sensor element 10 and is at least partially located on the gas diffusion path. The heater 30 is integrated on the sensor element 10 and is used to heat the sensor element 10. The functional electrode group includes an oxygen electrode unit 21, a reference electrode unit 22, a nitrogen oxide electrode unit 23, and a common electrode unit (not shown in the figure). The oxygen electrode unit 21 is used to pump oxygen and generate a first current signal positively correlated with the oxygen concentration. The reference electrode unit 22 is used to detect the oxygen partial pressure. The nitrogen oxide electrode unit 23 is used to decompose nitrogen oxides and generate a second current signal positively correlated with the nitrogen oxide concentration. The common electrode unit is electrically connected to the oxygen electrode unit 21, the reference electrode unit 22, and the nitrogen oxide electrode unit 23 respectively to form a common potential loop.
[0027] Among them, the ion-conducting material is, for example, a solid electrolyte matrix, which specifically includes zirconium oxide and alumina. In a specific embodiment, the sensor element 10 is formed by stacking and co-firing multiple layers of zirconium oxide 101 and alumina 102 green ceramic tapes to form an integral structure.
[0028] The oxygen electrode unit 21 includes a first electrode portion 211 and a second electrode portion 212. The first electrode portion 211 is disposed outside the gas diffusion path, and the second electrode portion 212 is disposed within a first chamber 13 located between the first diffusion barrier 11 and the second diffusion barrier 12 on the gas diffusion path. The second electrode portion 212 is an electrode made of a material that inhibits the decomposition of nitrogen oxides. By disposing the second electrode portion 212, made of a material that inhibits the decomposition of nitrogen oxides, within the first chamber 13, premature decomposition of nitrogen oxides in the first chamber 13 can be effectively prevented, ensuring that nitrogen oxides completely enter the second chamber 14 after the second diffusion barrier 12 for measurement, further improving the specificity and accuracy of the nitrogen oxide measurement signal. In a specific embodiment, the first electrode portion 211 is an external oxygen pump electrode, and the second electrode portion is an internal oxygen pump electrode. The oxygen electrode unit 21 consists of an external oxygen pump electrode and an internal oxygen pump electrode, and its corresponding current signal is an oxygen current. The internal oxygen pump electrode specifically adopts a gold-platinum-yttrium-stabilized zirconium oxide (Au-Pt-YSZ) composite electrode, which inhibits the decomposition reaction of nitric oxide. This further ensures that most of the nitric oxide in the measured gas remains and passes through the second diffusion barrier 12, while nitrogen dioxide diffuses to the second chamber 13 after passing through the second diffusion barrier 12 and decomposes into nitric oxide (NO) and oxygen atoms (O) on the catalytic surface of the nitrogen oxide electrode unit 23 (especially the fifth electrode part 231).
[0029] The reference electrode unit 22 includes a third electrode portion 221 and a fourth electrode portion 222. The third electrode portion 221 is disposed in the first chamber 13 located between the first diffusion barrier 11 and the second diffusion barrier 12 on the gas diffusion path. The third electrode portion 221 is electrically connected to the oxygen electrode unit 21 to sense the oxygen partial pressure near the oxygen electrode unit 21, i.e., the third electrode portion 221 is used to provide an oxygen partial pressure reference signal. The fourth electrode portion 222 is disposed in the second chamber 14 located after the second diffusion barrier 12 on the gas diffusion path, and the fourth electrode portion 222 is used to provide a potential reference. By disposing the reference electrode units 22 in the first chamber 13 and the second chamber 14 respectively, and using the electrode portion in the first chamber 13 to provide an oxygen partial pressure feedback signal, precise closed-loop control of the oxygen partial pressure in the first chamber 13 is achieved, providing a stable basis for the accurate measurement of oxygen concentration. In a specific embodiment, the third electrode portion 221 is a Nernst electrode used to sense the oxygen partial pressure in the first chamber 13, and the fourth electrode portion 222 is a reference electrode used to provide a stable point reference for the entire nitrogen-oxygen sensor system. Specifically, the Nernst electrode is used to detect the oxygen partial pressure of the internal oxygen pump electrode, and specifically, the Nernst electrode is located near the second diffusion barrier 12.
[0030] The nitrogen oxide electrode unit 23 includes a fifth electrode section 231 and a sixth electrode section 232. The fifth electrode section 231 and the sixth electrode section 232 are respectively disposed in the second chamber 14 located after the second diffusion barrier 12 along the gas diffusion path. The fifth electrode section 231 is electrically connected to the common electrode unit for decomposing nitrogen oxides. By centrally disposing of the nitrogen oxide electrode unit 23 in the second chamber and specifically decomposing nitrogen oxides under a low oxygen partial pressure environment, the generated pump current signal can more directly and accurately reflect the concentration of nitrogen oxides, reducing interference from other gases. In a specific embodiment, the fifth electrode section 231 is the NOx pump electrode, and the sixth electrode section is the NOx measuring electrode. Nitric oxide undergoes a catalytic decomposition reaction on the surface of the NOx pump electrode, breaking down into nitrogen and oxygen atoms. The oxygen component is pumped to the NOx measuring electrode, and the corresponding pump current signal directly reflects the content of nitrogen oxides (NOx) in the measured gas.
[0031] The first chamber 13 and the second chamber 14 are formed by stacking cavities pre-etched into the zirconium oxide layer 101. The first diffusion barrier 11 is implemented as a flow-limiting orifice penetrating the ceramic layer, while the second diffusion barrier 12 is a narrow diffusion channel connecting the two chambers. The oxygen electrode unit 21, the reference electrode unit 22, the oxynitride electrode unit 23, and the heater 30 are all prepared and sintered on the surface or inside the corresponding ceramic layer using screen printing technology. The common electrode unit is formed into a large-area conductive layer by screen printing, and is connected to the second electrode portion 212 of the oxygen electrode unit 21, the third electrode portion 221 of the reference electrode unit 22, and the fifth electrode portion 231 of the oxynitride electrode unit 23 respectively using interlayer conductive vias. Specifically, the internal oxygen pump electrode, the Nernst electrode, and the oxynitride pump electrode are all connected to the common electrode unit, together forming the common potential loop of the entire sensor.
[0032] like Figure 2 As shown in Embodiment 2 of the present invention, a nitrogen oxide sensing and control system is disclosed, including a processor 200 and the nitrogen oxide sensor 100 from Embodiment 1. The processor 200 is electrically connected to a functional electrode group and a heater 30. The processor 200 is configured to: control the operating state of the heater 30 to maintain the sensor element 10 at a predetermined operating temperature; apply a first voltage to the oxygen electrode unit 21 to regulate the oxygen partial pressure of the gas entering through the first diffusion barrier 11, and acquire a first current signal generated by the oxygen electrode unit 21; apply a second voltage to the nitrogen oxide electrode unit 23 to decompose nitrogen oxides in the gas entering through the second diffusion barrier 12, and acquire a second current signal generated by the nitrogen oxide electrode unit 23; and determine the oxygen concentration and nitrogen oxide concentration based on the first current signal and the second current signal. Through the intelligent control of the processor 200, the sensing and control system achieves precise regulation of the sensor operating temperature and the voltage of each electrode, as well as signal acquisition and processing, with a high degree of automation and reliable measurement results.
[0033] In a further embodiment, the processor 200 is also configured to: acquire a voltage signal characterizing the oxygen partial pressure generated by the reference electrode unit 22, and, based on the difference between the voltage signal and the target value, adjust the first voltage to stabilize the oxygen partial pressure in the first chamber 13 between the first diffusion barrier 11 and the second diffusion barrier 12 within the target range. By stabilizing the oxygen partial pressure in the first chamber 13 within the target range through the feedback adjustment mechanism, the stability of the oxygen measurement reference is ensured, thereby indirectly improving the accuracy of nitrogen oxide measurement. In a specific embodiment, if the measured Nernst voltage deviates from the target value (e.g., the target value is 400mV), the processor 200 can further adjust the Nernst voltage to the target value by increasing or decreasing the first voltage. The oxygen partial pressure in the measured gas will be reduced to an extremely low and almost constant level (e.g., oxygen partial pressure below 1ppm), that is, a stable low oxygen partial pressure environment is established and maintained within the first chamber 13. Due to the low oxygen partial pressure environment inside the first chamber 13, nitric oxide in the first chamber 13, as well as nitric oxide obtained from the decomposition of nitrogen dioxide at the second diffusion barrier 12, will pass through the second diffusion barrier 12 and enter the second chamber 14. The target voltage value for oxygen partial pressure feedback control (e.g., 400mV) corresponds to an extremely low oxygen partial pressure setpoint (e.g., 10mV) in the first chamber. -15 (atm), this setpoint is calculated by relating it to the operating temperature using the Nernst equation.
[0034] In a further embodiment, the nitrogen oxide sensing and control system also includes an analog-to-digital converter (ADC) 300 and a communication unit 400. The ADC 300 is connected between the functional electrode group and the processor 200, and is used to convert the current signal generated by the functional electrode group into a digital signal. The communication unit 400 is connected to the output terminal of the processor 200 to output the oxygen concentration and nitrogen oxide concentration in the gas. By setting up the ADC 300 and the communication unit 400, high-precision conversion of analog signals to digital signals and standardized data interaction with external systems are achieved, improving the system's integration and practicality.
[0035] The heater 30 heats the sensor element 10 to a predetermined operating temperature using a pre-defined heating strategy. To determine the temperature of the sensor element 10, the processor 200 uses the internal resistance of the reference electrode unit 22 for judgment; that is, while controlling the operating state of the heater 30, it can determine whether the sensor element has reached the predetermined operating temperature by monitoring the internal resistance of the reference electrode unit 22. The internal resistance of the reference electrode unit 22 has a known functional relationship with temperature, and the current temperature can be calculated by measuring its impedance. Specifically, the predetermined operating temperature is typically 700℃~850℃. Within this temperature range, the zirconium oxide electrolyte has sufficient oxygen ion conductivity and optimal electrode catalytic activity.
[0036] like Figure 3aThe current in oxygen electrode unit 21 is positively correlated with the oxygen content, such as... Figure 3b The current of the nitrogen oxide electrode unit 23 is positively correlated with the nitrogen oxide value. Therefore, the relationship between the current of the oxygen electrode unit 21 and the oxygen value, as well as the relationship between the current of the nitrogen oxide electrode unit 23 and the nitrogen oxide value, can be determined through atmosphere calibration. The obtained oxygen and nitrogen oxide values are then processed by the processor 200 and output to the user via the communication unit 400, which may be, for example, a CAN communication unit.
[0037] The working principle of the nitrogen oxide sensing and control system in this embodiment is as follows: External gas enters the sensor element 10 through the first diffusion barrier 11, serving as the input medium for detection. The analog-to-digital conversion unit 300 receives electrical signals from the oxygen electrode unit 21, the common electrode unit 24, the reference electrode unit 22, and the nitrogen oxide electrode unit 23, converts these electrical signals into digital signals, and transmits them unidirectionally to the processor 200 for calculation and analysis. The processor 200, as the data processing core, unidirectionally outputs the analyzed and calculated detection results through the interface of the communication unit 400, realizing data interaction with external systems.
[0038] This invention discloses a method for measuring nitrogen and oxygen using a nitrogen-oxygen sensor in Embodiment 3. The method refers to measuring the concentration of oxygen and nitrogen oxides in a gas. Specifically, it uses the nitrogen-oxygen sensor from Embodiment 1, and can further utilize the nitrogen oxide sensing and control system from Embodiment 2. The method includes the following steps: controlling the operating state of the heater 30 to maintain the sensor element 10 at a predetermined operating temperature; applying a first voltage to the oxygen electrode unit 21 to regulate the oxygen partial pressure of the gas entering through the first diffusion barrier 11, and acquiring a first current signal generated by the oxygen electrode unit 21; applying a second voltage to the nitrogen oxide electrode unit 23 to decompose nitrogen oxides in the gas entering through the second diffusion barrier 12, and acquiring a second current signal generated by the nitrogen oxide electrode unit 23; and determining the oxygen and nitrogen oxide concentrations in the gas based on the first and second current signals. The measurement method in this embodiment has clear steps, and through temperature control, staged oxygen pumping, and decomposition measurement, it achieves high-precision, low-interference detection of oxygen and nitrogen oxides.
[0039] In a further embodiment, the method further includes: acquiring a voltage signal characterizing the oxygen partial pressure generated by the reference electrode unit 22, and adjusting a first voltage based on the difference between the voltage signal and a target value, so as to stabilize the oxygen partial pressure in the first chamber 13 between the first diffusion barrier 11 and the second diffusion barrier 12 within the target range. Introducing a feedback adjustment step into the measurement method further ensures the stability of the measurement process and the accuracy of the results.
[0040] In a further embodiment, when controlling the operating state of the heater 30, the internal resistance of the reference electrode unit 22 is monitored to determine whether the sensor element 10 has reached the predetermined operating temperature. This method of determining the operating temperature by monitoring the internal resistance of the reference electrode unit provides a reliable and integrated temperature monitoring method, eliminating the need for an additional temperature sensor and simplifying the structure.
[0041] The nitrogen-oxygen sensor disclosed in this invention measures the oxygen and nitrogen oxide concentrations in a gas using an electrochemical method. Compared to traditional sensor structures, this method reduces the number of auxiliary oxygen electrode units and heating wire electrodes, lowering the risk of signal coupling and achieving higher measurement accuracy. It also exhibits higher stability, maintaining the output temperature even during long-term operation, thus extending the sensor's lifespan, reducing replacement frequency, and lowering maintenance costs. The novel nitrogen-oxygen sensor in this embodiment consists of a sensor element, an oxygen electrode unit, a common electrode unit, a reference electrode unit, a nitrogen oxide electrode unit, and a heater (composed of two heating wire electrodes and a heating wire control unit). The processor precisely controls the heating wire control unit to ensure the sensor's operating temperature. External gas passes through the first diffusion barrier to the oxygen electrode unit. The processor applies voltage to the oxygen electrode unit, pumping oxygen out and simultaneously measuring the generated current, which is positively correlated with the oxygen concentration. The gas then passes through the second diffusion barrier to the NOx electrode unit. The processor applies voltage to the NOx electrode unit and simultaneously measures the generated current, which is positively correlated with the NOx concentration. The processor converts and calibrates the atmosphere to obtain the corresponding oxygen and NOx values, and outputs the results to the user via CAN communication for application in the exhaust gas aftertreatment system.
[0042] This invention optimizes the sensor structure and electrode configuration, reducing the number of electrodes (traditional nitrogen and oxygen sensors have an additional auxiliary oxygen electrode and a heating wire electrode, which are typically made of platinum, increasing costs) and simplifying the control system, thereby achieving higher measurement accuracy and stability. Specifically, by setting two diffusion barriers and a specific electrode layout, the risk of signal coupling is effectively reduced; by using materials that inhibit the decomposition of nitrogen oxides to fabricate specific electrodes, the influence of interference factors is reduced; and through precise temperature control and feedback adjustment mechanisms, the stable operation of the sensor under different operating conditions is ensured. The synergistic effect of these technical features makes this invention, compared with existing technologies, have higher measurement accuracy, better anti-interference ability, longer service life, lower manufacturing cost, higher resistance to poisoning, and better high-temperature performance and robustness.
[0043] The background section of this invention may include background information about the problems or circumstances surrounding the invention, rather than a description of prior art by others. Therefore, the content included in the background section is not an admission of prior art by the applicant.
[0044] The above description provides a further detailed explanation of the present invention in conjunction with specific / preferred embodiments, and it should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, various substitutions or modifications can be made to these described embodiments without departing from the concept of the present invention, and all such substitutions or modifications should be considered within the scope of protection of the present invention. In the description of this specification, the reference to terms such as "an embodiment," "some embodiments," "preferred embodiment," "example," "specific example," or "some examples," etc., indicates that the specific features, structures, materials, or characteristics described in connection with that embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in any suitable manner in one or more embodiments or examples. Furthermore, those skilled in the art can combine and integrate different embodiments or examples and features of different embodiments or examples described in this specification without contradiction. Although the embodiments of the present invention and their advantages have been described in detail, it should be understood that various changes, substitutions, and modifications can be made herein without departing from the scope defined by the appended claims.
Claims
1. A nitrogen and oxygen sensor, characterized in that, include: The sensor element is made of an ion-conductive material. The sensor element has a gas diffusion path inside, and a first diffusion barrier and a second diffusion barrier are arranged sequentially on the gas diffusion path. A functional electrode assembly is disposed on the sensor element and is at least partially located on the gas diffusion path; A heater, integrated on the sensor element, is used to heat the sensor element; The functional electrode assembly includes an oxygen electrode unit, a reference electrode unit, a nitrogen oxide electrode unit, and a common electrode unit. The oxygen electrode unit is used to pump oxygen and generate a first current signal positively correlated with the oxygen concentration. The reference electrode unit is used to detect the oxygen partial pressure. The nitrogen oxide electrode unit is used to decompose nitrogen oxides and generate a second current signal positively correlated with the nitrogen oxide concentration. The common electrode unit is electrically connected to the oxygen electrode unit, the reference electrode unit, and the nitrogen oxide electrode unit to form a common potential loop.
2. The nitrogen and oxygen sensor according to claim 1, characterized in that, The oxygen electrode unit includes a first electrode portion and a second electrode portion. The first electrode portion is disposed outside the gas diffusion path, and the second electrode portion is disposed in a first chamber located between the first diffusion barrier and the second diffusion barrier on the gas diffusion path. The second electrode portion is an electrode made of a material that inhibits the decomposition of nitrogen oxides.
3. The nitrogen and oxygen sensor according to claim 1, characterized in that, The reference electrode unit includes a third electrode portion and a fourth electrode portion. The third electrode portion is disposed in a first chamber located between the first diffusion barrier and the second diffusion barrier on the gas diffusion path. The third electrode portion is electrically connected to the oxygen electrode unit to provide an oxygen partial pressure reference signal. The fourth electrode portion is disposed in a second chamber located after the second diffusion barrier on the gas diffusion path, and the fourth electrode portion is used to provide a potential reference.
4. The nitrogen and oxygen sensor according to claim 1, characterized in that, The nitrogen oxide electrode unit includes a fifth electrode section and a sixth electrode section, which are respectively disposed in a second chamber located after the second diffusion barrier on the gas diffusion path. The fifth electrode section is electrically connected to the common electrode unit for decomposing nitrogen oxides.
5. A nitrogen oxide sensing and control system, characterized in that, include: The nitrogen and oxygen sensor according to any one of claims 1 to 4; The processor is electrically connected to the functional electrode group and the heater; The processor is configured to: control the operating state of the heater to maintain the sensor element at a predetermined operating temperature; apply a first voltage to the oxygen electrode unit to regulate the oxygen partial pressure of the gas entering through the first diffusion barrier, and acquire the first current signal generated by the oxygen electrode unit; apply a second voltage to the nitrogen oxide electrode unit to decompose nitrogen oxides in the gas entering through the second diffusion barrier, and acquire the second current signal generated by the nitrogen oxide electrode unit; and determine the oxygen concentration and nitrogen oxide concentration based on the first current signal and the second current signal.
6. The nitrogen oxide sensing and control system according to claim 5, characterized in that, The processor is further configured to: acquire a voltage signal representing the oxygen partial pressure generated by the reference electrode unit, and adjust the first voltage based on the difference between the voltage signal and the target value, so as to stabilize the oxygen partial pressure in the first chamber between the first diffusion barrier and the second diffusion barrier within the target range.
7. The nitrogen oxide sensing and control system according to claim 5, characterized in that, It also includes an analog-to-digital conversion unit and a communication unit. The analog-to-digital conversion unit is connected between the functional electrode group and the processor and is used to convert the current signal generated by the functional electrode group into a digital signal. The communication unit is connected to the output terminal of the processor and is used to output the oxygen concentration and nitrogen oxide concentration in the gas.
8. A method for measuring nitrogen and oxygen using a nitrogen and oxygen sensor according to any one of claims 1 to 4, characterized in that, Includes the following steps: The operating state of the heater is controlled to maintain the sensor element at a predetermined operating temperature; A first voltage is applied to the oxygen electrode unit to regulate the oxygen partial pressure of the gas entering through the first diffusion barrier, and the first current signal generated by the oxygen electrode unit is acquired. A second voltage is applied to the nitrogen oxide electrode unit to decompose nitrogen oxides in the gas that enters through the second diffusion barrier, and a second current signal generated by the nitrogen oxide electrode unit is acquired. The oxygen concentration and nitrogen oxide concentration in the gas are determined based on the first current signal and the second current signal.
9. The method for measuring nitrogen and oxygen according to claim 8, characterized in that, Also includes: The voltage signal representing the oxygen partial pressure generated by the reference electrode unit is acquired, and the first voltage is adjusted based on the difference between the voltage signal and the target value to stabilize the oxygen partial pressure in the first chamber between the first diffusion barrier and the second diffusion barrier within the target range.
10. The method for measuring nitrogen and oxygen according to claim 8, characterized in that, When controlling the operating state of the heater, the internal resistance of the reference electrode unit is monitored to determine whether the sensor element has reached the predetermined operating temperature.