A nitrogen-oxygen sensor ceramic chip for improving NOx detection accuracy

Abstract

The application discloses a kind of for improving NO x Detection precision nitrogen oxide sensor ceramic chip belongs to nitrogen oxide sensor ceramic chip technical field, by parallel placement of monitoring electrode and measuring electrode at the position of same distance from gas diffusion port, can make the gas temperature of two electrodes equal, based on this, monitoring electrode is positioned so that it can be detected at measuring electrode and monitoring electrode equally by the current generated by electron conduction.The current between measuring electrode and reference electrode is the sum of "NO x The current generated by electron conduction", the current between monitoring electrode and reference electrode is "electron conduction generated current", "the current between measuring electrode and reference electrode" minus "monitoring electrode and reference electrode" can eliminate the influence of electron conduction, that is, eliminate the influence of residual O2, measure "NO x Current", to improve the measurement accuracy of NO x Sensor.

Description

Technical Field

[0001] This invention belongs to the field of nitrogen and oxygen sensor ceramic chip technology, and particularly relates to a nitrogen and oxygen sensor ceramic chip for improving the accuracy of NOx detection. Background Technology

[0002] my country currently implements the my country VI emission standard for heavy-duty diesel vehicles, indicating that the country's standards for vehicle exhaust emissions are becoming increasingly stringent. Among these standards, effectively improving NO₂ levels in the lean-mixed combustion zone is crucial. x Purification capability is the primary task in managing vehicle exhaust emissions. This is crucial for treating NO in exhaust environments where oxygen and other compounds coexist. x Further improvements in reduction and purification are needed to enhance the performance of SCR (Selective Catalytic Reduction) systems using urea and fuel components (hydrocarbons) as reducing agents. NO is detected by a nitrogen oxide sensor installed upstream of the SCR system. x By arranging the quantities accordingly, the amount of reducing agent used can be optimized, and the NO content measured by the nitrogen and oxygen sensor installed downstream of the SCR system can be further improved. x By adjusting the amount of reductant, the required amount of catalyst can be reduced. To this end, in order to improve the performance of SCR systems, large-scale systems with high costs have been unavoidable. Related technologies have employed methods such as increasing the amount of reductant and increasing the volume of the SCR catalyst. Given the urgent need for miniaturization and cost reduction in modern industry, optimizing the amount of reductant used and reducing the number of catalysts necessitates improving the methods used for detecting NO. x The accuracy of the nitrogen and oxygen sensor.

[0003] Existing nitrogen and oxygen sensor ceramic chips are used to detect NO. x The concentration is typically as follows: O2 is pumped out through the internal electrode, and the remaining NO... x The electrode being measured decomposes, and when oxygen ions are conducted through the solid electrolyte, NO... x The concentration was detected as an electric current. The inventors believed that this was necessary for detecting NO at the ppm level. x For high-precision detection of minute currents in the nA range, O2 removal at the pump electrode is crucial. If insufficient O2 removal occurs, the remaining O2 will reach the measuring electrode as residual O2, and the obtained current value will be the sum of the current generated by O2 and the current generated by NO. x The generated current, the detected value, and the actual NO x The concentration is incorrect. Therefore, it is necessary to design a method to increase NO concentration. x A ceramic chip for nitrogen and oxygen sensors with high detection accuracy.

[0004] It should be noted that the information disclosed in the background section above is only used to enhance the understanding of the background of this disclosure, and therefore may include information that does not constitute prior art. Summary of the Invention

[0005] Through research, the inventors discovered that, in their view, the nitrogen-oxygen sensor is a solid electrolyte, and the current generated by residual O2 on the measuring electrode will interact with the current generated by NO. x The resulting currents are added together, interfering with the actual NO. x The measured concentration leads to a decrease in detection accuracy. Eliminating the influence of residual O2 is necessary to improve the NO concentration of the ceramic chip in the nitrogen and oxygen sensor. x Detection accuracy.

[0006] In view of at least one of the above-mentioned technical problems, this disclosure provides a nitrogen oxide sensor ceramic chip for improving the accuracy of NOx detection, and the specific technical solution is as follows:

[0007] A nitrogen oxide sensor ceramic chip for improving NOx detection accuracy includes a chip body. The chip body includes a zirconia substrate I, an external electrode on the upper surface of the zirconia substrate I, and a porous protective layer covering the external electrode. A zirconia substrate II is stacked on one side of the bottom surface of the zirconia substrate I, and a zirconia substrate III is stacked on the bottom surface of the zirconia substrate II. The shape of the zirconia substrate III is consistent with that of the zirconia substrate I. A measurement chamber is provided on one side of the zirconia substrate II, and a diffusion barrier is provided at the port of the measurement chamber. A main pump electrode is provided on the bottom surface of the measurement chamber. Measuring electrodes and monitoring electrodes are arranged in parallel. The distance between the measuring electrode and the port of the measuring chamber is equal to the distance between the monitoring electrode and the port of the measuring chamber. Zirconia substrate III is stacked on one side of its bottom surface, and zirconia substrate IV is stacked on the bottom surface of zirconia substrate IV. A reference chamber is provided on one side of zirconia substrate IV, and a reference electrode is provided on the top surface of the reference chamber. The reference electrode is located below the main pump electrode, measuring electrode, and monitoring electrode. Zirconia substrate V is stacked on the bottom surface of zirconia substrate V, and a heater is provided between zirconia substrate V and zirconia substrate VI.

[0008] In some embodiments of this disclosure, the diffusion barrier is made of a porous ceramic material.

[0009] In some embodiments of this disclosure, the external electrode is made of pure platinum.

[0010] In some embodiments of this disclosure, both the main pump electrode and the monitoring electrode are made of platinum.

[0011] In some embodiments of this disclosure, both the main pump electrode and the monitoring electrode are made of Pt-Au precious metal porous slurry.

[0012] In some embodiments of this disclosure, the measuring electrode is made of platinum-rhodium material.

[0013] In some embodiments of this disclosure, the heater includes a heating electrode located at the projection of the main pump electrode.

[0014] In some embodiments of this disclosure, the heater is covered with an insulating sheet.

[0015] In some embodiments of this disclosure, the insulating sheet is an alumina insulating sheet.

[0016] Compared with the prior art, the present invention has the following advantages: By placing the monitoring electrode and the measuring electrode parallel to each other at the same distance from the gas diffusion port, the gas temperature of the two electrodes can be made equal. Based on this, the monitoring electrode is positioned so that the current generated by electron conduction can be detected equally at both the measuring electrode and the monitoring electrode. The current between the measuring electrode and the reference electrode is "NO". x The sum of the current generated and the current generated by electron conduction, and the current between the monitoring electrode and the reference electrode is the "current generated by electron conduction". Subtracting the "current between the monitoring electrode and the reference electrode" from the "current between the measuring electrode and the reference electrode" eliminates the influence of electron conduction, i.e., eliminates the influence of residual O2, and thus the measured "NO". x "Current", thereby increasing NO x Sensor measurement accuracy. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the structure of the present invention;

[0018] Figure 2 for Figure 1 A schematic diagram of AA in the diagram.

[0019] The following are the labels in the diagram: 1. Zirconia substrate I; 11. External electrode; 12. Porous protective layer; 2. Zirconia substrate II; 3. Zirconia substrate III; 4. Measuring chamber; 41. Diffusion barrier; 42. Main pump electrode; 43. Measuring electrode; 44. Monitoring electrode; 5. Zirconia substrate IV; 6. Zirconia substrate V; 7. Reference chamber; 71. Reference electrode; 8. Zirconia substrate VI; 9. Heater; 91. Heating electrode; 92. Insulating sheet. Detailed implementation method:

[0020] To better understand the purpose, structure, and function of this invention, the technical solutions in the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this invention, and not all embodiments.

[0021] The component numbers used in this document are solely for distinguishing the objects described and have no sequential or technical meaning. The term "connection" in this disclosure, unless otherwise specified, includes both direct and indirect connections. In the description of this application, it should be understood that directional terms such as "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms are used solely for the convenience of describing this application and for a brief description, and do not indicate or imply that the device or unit 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 this application.

[0022] As shown in the attached diagram. Figures 1 to 2 As shown, a nitrogen oxide sensor ceramic chip for improving NOx detection accuracy is disclosed, comprising a chip body, wherein the chip body includes a zirconia substrate I1, an external electrode 11 is provided on the upper surface of the zirconia substrate I1, the external electrode 11 is disposed at a local position on the surface of the zirconia substrate I1, the external electrode 11 is made of pure platinum material, catalyzes oxygen ions to lose electrons to generate oxygen, and leads the oxygen out of the chip body, the external electrode 11 is covered with a porous protective layer 12, a zirconia substrate II2 is stacked on one side of the bottom surface of the zirconia substrate I1, and a zirconia substrate III3 is stacked on the bottom surface of the zirconia substrate II2. Substrate III3 has the same shape as zirconia substrate I1. A measurement chamber 4 is located on one side of zirconia substrate II2. A diffusion barrier 41, made of porous ceramic material, is located at the port of measurement chamber 4 to prevent excessive airflow from impacting the chip body. A main pump electrode 42 is located on the bottom surface of measurement chamber 4. A measurement electrode 43 and a monitoring electrode 44 are arranged side-by-side inside the main pump electrode 42. The distance between the measurement electrode 43 and the port of measurement chamber 4 is equal to the distance between the monitoring electrode 44 and the port of measurement chamber 4. Both the main pump electrode 42 and the monitoring electrode 44 are made of platinum to suppress NO. x In this disclosure, the material can be a Pt-Au precious metal porous slurry, and the measuring electrode 43 is made of platinum-rhodium material, which catalyzes NO. xThe zirconia substrate III3 has a zirconia substrate IV5 stacked on one side of its bottom surface, and a zirconia substrate V6 stacked on the bottom surface of IV5. A reference chamber 7 is located on one side of IV5, and a reference electrode 71 is located on the top surface of the reference chamber 7, below the main pump electrode 42, measuring electrode 43, and monitoring electrode 44. A zirconia substrate VI8 is stacked on the bottom surface of V6, and a heater 9 is located between V6 and VI8. The current between the main pump electrode 42 and the reference electrode 71 is used to measure the oxygen concentration entering the measuring chamber 4. By placing the monitoring electrode 44 parallel to the measuring electrode 43 at the same distance from the gas diffusion port, the gas temperature of the two electrodes can be made equal. Based on this, the monitoring electrode 44 is positioned so that the current generated by electron conduction can be detected equally at both the measuring electrode 43 and the monitoring electrode 44. The current between the measuring electrode 43 and the reference electrode 71 is "NO". x The sum of the generated current and the current generated by electron conduction, i.e., NO x The current between monitoring electrode 44 and reference electrode 71, and the residual O2 concentration, is the "electron conduction current," i.e., the residual O2 concentration. Subtracting the current between monitoring electrode 44 and reference electrode 71 from the current between measuring electrode 43 and reference electrode 71 eliminates the influence of electron conduction, thus eliminating the influence of residual O2, and thus the measured NO concentration. x "Current", thereby increasing NO x Sensor measurement accuracy.

[0023] Using specimens to study electron conduction on NO x The influence of the sensor. The area of ​​the measuring electrode on the test piece is equal to the area of ​​the actual sensor. A ceramic heating tube is used to maintain a constant temperature of the chip body. N2 is used as the measuring gas, and a potentiostat is used to measure the current value at the relevant temperature. In practical use, NO... x At the sensor's temperature, current generated by electronic conduction is added to NO. x In the current measured by the sensor. If the temperature can remain constant, the current generated by electronic conduction will not change. However, in NO... x Stable temperature control in the sensor's operating environment is impractical. By placing the monitoring electrode 44 parallel to the measuring electrode 43 at the same distance from the gas diffusion port, the gas temperature of the two electrodes can be made equal. Based on this, the monitoring electrode is positioned so that the current generated by electronic conduction can be detected equally at both the measuring electrode and the monitoring electrode. The current between the measuring electrode 43 and the reference electrode 71 is the sum of the current generated by NOx and the current generated by electronic conduction, while the current between the monitoring electrode 44 and the reference electrode 71 is the current generated by electronic conduction. x"Current" is defined as "measuring current" minus "monitoring current," which eliminates the influence of electron conduction, thereby improving NO. x Sensor measurement accuracy.

[0024] It is understood that the present invention has been described through some embodiments, and those skilled in the art will recognize that various changes or equivalent substitutions can be made to these features and embodiments without departing from the spirit and scope of the invention. Furthermore, under the teachings of the present invention, these features and embodiments can be modified to adapt to specific situations and materials without departing from the spirit and scope of the invention. Therefore, the present invention is not limited to the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of this application are within the protection scope of the present invention.

Claims

1. A nitrogen oxide sensor ceramic chip for improving NOx detection accuracy, comprising a chip body, characterized in that: The chip body includes a zirconia substrate I (1), an external electrode (11) on the upper surface of the zirconia substrate I (1), the external electrode (11) being covered with a porous protective layer (12), a zirconia substrate II (2) stacked on one side of the bottom surface of the zirconia substrate I (1), a zirconia substrate III (3) stacked on the bottom surface of the zirconia substrate II (2), the shape of the zirconia substrate III (3) being consistent with that of the zirconia substrate I (1), a measurement chamber (4) on one side of the zirconia substrate II (2), a diffusion barrier (41) at the port of the measurement chamber (4), a main pump electrode (42) on the bottom surface of the measurement chamber (4), and a measurement electrode (43) and a monitoring electrode (44) arranged side by side on the inner side of the main pump electrode (42). The distance between the electrode (43) and the port of the measuring chamber (4) is equal to the distance between the monitoring electrode (44) and the port of the measuring chamber (4). Zirconia substrate III (3) is stacked on one side of the bottom surface of the zirconia substrate IV (5), and zirconia substrate IV (5) is stacked on the bottom surface of the zirconia substrate V (6). A reference chamber (7) is provided on one side of the zirconia substrate IV (5). A reference electrode (71) is provided on the top surface of the reference chamber (7). The reference electrode (71) is located below the main pump electrode (42), the measuring electrode (43) and the monitoring electrode (44). Zirconia substrate V (6) is stacked on the bottom surface of the zirconia substrate VI (8). A heater (9) is provided between the zirconia substrate V (6) and the zirconia substrate VI (8). The current between the measuring electrode (43) and the reference electrode (71) is the current generated by NOx and the current generated by electron conduction. The current between the monitoring electrode (44) and the reference electrode (71) is the current generated by electron conduction. The influence of electron conduction can be eliminated by subtracting the current between the measuring electrode (43) and the reference electrode (71) from the current between the monitoring electrode (44) and the reference electrode (71).

2. The method for improving NO according to claim 1 x A nitrogen and oxygen sensor ceramic chip with high detection accuracy is characterized by, The diffusion barrier (41) is made of porous ceramic material.

3. The method for improving NO according to claim 1 x A nitrogen and oxygen sensor ceramic chip with high detection accuracy is characterized by, The external electrode (11) is made of pure platinum.

4. The method for increasing NO according to claim 1 x A nitrogen and oxygen sensor ceramic chip with high detection accuracy is characterized by, Both the main pump electrode (42) and the monitoring electrode (44) are made of platinum.

5. The method for improving NO according to claim 4 x A nitrogen and oxygen sensor ceramic chip with high detection accuracy is characterized by, Both the main pump electrode (42) and the monitoring electrode (44) are made of Pt-Au precious metal porous slurry.

6. The method for improving NO according to claim 1 x A nitrogen and oxygen sensor ceramic chip with high detection accuracy is characterized by, The measuring electrode (43) is made of platinum-rhodium material.

7. The method for improving NO according to claim 1 x A nitrogen and oxygen sensor ceramic chip with high detection accuracy is characterized by, The heater (9) includes a heating electrode (91) located at the projection point below the main pump electrode (42).

8. The method for improving NO according to claim 7 x A nitrogen and oxygen sensor ceramic chip with high detection accuracy is characterized by, The heater (9) is covered with an insulating sheet (92).

9. The method for improving NO according to claim 8 x A nitrogen and oxygen sensor ceramic chip with high detection accuracy is characterized by, The insulating sheet (92) is an alumina insulating sheet.

Images