CN214174230U

CN214174230U - Improved nitrogen-oxygen sensor chip

Info

Publication number: CN214174230U
Application number: CN202023152928.1U
Authority: CN
Inventors: 郑钢; 田晶; 张鉴隆; 黄晓明; 张立红; 叶立清; 刘岩
Original assignee: Guangdong Lingnan Institute of Technology
Current assignee: Guangdong Lingnan Institute of Technology
Priority date: 2020-12-24
Filing date: 2020-12-24
Publication date: 2021-09-10
Anticipated expiration: 2030-12-24

Abstract

The utility model discloses a modified nitrogen oxygen sensor chip, include: the ceramic chip substrate is in a wafer shape and comprises N layers of zirconium oxide substrates formed by stacking and sintering, a common outer electrode is arranged on the upper surface of the first layer of zirconium oxide substrate, an air inlet, a first pumping oxygen chamber and a second pumping oxygen chamber are sequentially arranged on the second layer of zirconium oxide substrate, and the air inlet is connected with the first pumping oxygen chamber and the first pumping oxygen chamber are connected with the second pumping oxygen chamber through circular-arc channels; the bottom of the third layer of zirconia substrate is printed with a reference electrode, the third layer of zirconia substrate is provided with a reference channel communicated with the outside, the reference electrode is contacted with the outside atmosphere, the bottom of the fourth layer of zirconia substrate is printed with an annular heating electrode, and the shape of the annular heating electrode is consistent with that of the ceramic chip substrate. The utility model discloses can reduce stress concentration in sintering process, can also suitably prolong tail gas transit time, pump oxygen efficiency improves, and heating temperature is even, improves heating performance.

Description

Improved nitrogen-oxygen sensor chip

Technical Field

The utility model relates to a nitrogen oxygen sensor technical field, concretely relates to modified nitrogen oxygen sensor chip.

Background

The gas sensor is a core component for controlling a modern engine, accurate parameters measured by the gas sensor are not available, and a good control function cannot be realized, so that the gas sensor technology is always a key technology advocated by the policy of the automobile industry. Nitrogen Oxides (NO)_X) Sensor for measuring nitrogen monoxide (NO) and nitrogen dioxide (NO) in tail gas of diesel engine₂) The content of (b) is used for controlling the engine or monitoring the working state of the exhaust emission aftertreatment system, and is a key component for energy conservation and emission reduction of the engine. According to the requirement of the Chinese national 5-emission standard, the nitrogen oxide sensor is mainly used for a diesel vehicle with more than 3.5 tons and used for monitoring the working state of an SCR (selective catalytic reduction) system. After the stricter Chinese 6 emission standards are implemented, the nitrogen oxide sensor is also used for closed-loop control of the diesel engine.

The core component of the nitrogen-oxygen sensor is a nitrogen-oxygen sensor chip, and the structure of the conventional typical nitrogen-oxygen sensor chip is basically in a strip shape, as shown in fig. 1. The substrate is formed by stacking and sintering 6 pieces of zirconia (a-f), and 5 or 7 pieces of zirconia are stacked and sintered. NO in automobile exhaust_XEnters the first cavity o through the first aluminum oxide diffusion barrier l by the channel m, part of oxygen in the tail gas is pumped out by the first oxygen pumping electrode consisting of the platinum electrode n and the common outer electrode p, and NO is simultaneously pumped out₂Decomposed to NO. The tail gas with the reduced concentration enters the second aluminum oxide diffusion barrier rA second oxygen pumping chamber s for pumping out the residual oxygen in the mixed gas by a second oxygen pumping electrode composed of a platinum electrode t and a common outer electrode p and simultaneously pumping out the residual NO₂Decomposed to NO. The tail gas without oxygen enters a third chamber v through a third aluminum oxide diffusion barrier u, a high catalytic activity material rhodium is mixed in a measurement platinum electrode w in the third chamber, gas is subjected to decomposition reaction at high temperature, NO is decomposed into nitrogen and oxygen, the oxygen is pumped out by a third pump oxygen electrode consisting of the measurement platinum electrode w and a common external electrode p, and the NO in the automobile exhaust gas can be obtained by measuring the micro-current value of the third pump oxygen electrode_XThe concentration value of (c). And a reference electrode j is printed at the bottom of the third zirconia layer c, a reference channel g communicated with the outside is formed in the third zirconia layer c, the reference electrode j is in contact with the outside atmosphere to always ensure stable oxygen partial pressure, and the reference electrode j and the platinum electrode w form a loop to provide a reference value. And a heating electrode h is printed at the bottom of the fourth zirconia layer d, so that the ceramic chip can be heated to a set temperature in a short time. The first oxygen pumping electrode n, the second oxygen pumping electrode t and the measurement platinum electrode w can be coated with an alumina protective layer. The public outer electrode p is coated with a porous alumina protective layer q, the reference electrode j is coated with a porous alumina protective layer k, and the heating electrode h is coated with an insulating compact alumina protective layer i.

The long strip-shaped ceramic chip structure has the advantages that the tail gas transmission track is a straight line, the transmission distance from the gas inlet to the last chamber is short, the blocking effect of the diffusion barrier can be affected, and the flow speed and the flow of the tail gas are unstable. Especially, when the concentration and the temperature of the tail gas fluctuate, the measurement precision shows an unstable phenomenon in the process of pumping oxygen, and the pumped oxygen quantity is not matched with the set voltage value of the oxygen pumping electrode, so that the measurement precision is influenced. And the air inlet channel and the main cavity of the strip-shaped ceramic chip structure are concentrated at the front part of the chip, and the distance between the cavities is short, so that the front part is easy to collapse due to stress concentration after long-term working and high-temperature action. In addition, the shape of the heating electrode is also mostly strip-shaped, and the heating temperature distribution is unbalanced due to uneven distribution of the ceramic chip chamber in the heating process, so that the final measurement precision is influenced.

Therefore, there is a need in the industry to develop a ceramic oxynitride sensor chip with other shapes, which has uniform heating temperature and can improve the measurement accuracy

SUMMERY OF THE UTILITY MODEL

The utility model aims at overcoming the deficiencies of the prior art, providing a heating temperature is even, improves heating performance, improves measurement accuracy's modified nitrogen oxygen sensor chip.

The purpose of the utility model is realized through the following technical scheme:

an improved nitroxide sensor chip comprising: the ceramic chip substrate is in a wafer shape and comprises N layers of zirconium oxide substrates which are formed by stacking and sintering, wherein N is not less than 5; the upper surface of the first layer of zirconia substrate is provided with a common outer electrode, the common outer electrode is coated with a first porous alumina protective layer, the second layer of zirconia substrate is sequentially provided with an air inlet, a first pumping oxygen chamber and a second pumping oxygen chamber, the air inlet and the first pumping oxygen chamber are connected, and the first pumping oxygen chamber and the second pumping oxygen chamber are connected through circular-arc channels; a reference electrode is printed at the bottom of the third layer of zirconia substrate, the reference electrode wraps the second porous alumina protective layer, a reference channel communicated with the outside is arranged on the third layer of zirconia substrate, the reference electrode is contacted with the outside atmosphere, an annular heating electrode is printed at the bottom of the fourth layer of zirconia substrate, the annular heating electrode wraps the insulating compact alumina protective layer, the shape of the annular heating electrode is consistent with that of the ceramic chip substrate,

preferably, the second layer of zirconia substrate is provided with a circular arc-shaped first diffusion barrier, the head end of the first diffusion barrier is provided with an air inlet, the tail end of the first diffusion barrier is connected to the first pumped oxygen chamber, a first platinum electrode is printed in the first pumped oxygen chamber, the other end of the first pumped oxygen chamber is connected to the head end of the circular arc-shaped second diffusion barrier, the tail end of the second diffusion barrier is connected to the second pumped oxygen chamber, and the first platinum electrode and the platinum electrode for measurement are printed in the second pumped oxygen chamber.

Preferably, the first diffusion barrier is a porous alumina material.

Preferably, N ═ 5.

Compared with the prior art, the utility model have following advantage:

the utility model discloses a ceramic chip base member adopts disc form zirconia stack sintering, evenly sets up air inlet, first pump oxygen cavity on the second floor zirconia base member in proper order, and second pump oxygen cavity measures the cavity and merges and merge at second pump oxygen cavity, reduces cavity quantity, effectively avoids ceramic chip local collapse. The lengthened arc-shaped diffusion barrier channel is designed, so that stress concentration is reduced in the sintering process, tail gas passing time can be properly prolonged, and oxygen pumping efficiency is improved. The second oxygen pumping chamber pumps out residual oxygen completely, so that the phenomenon of unstable measurement precision is improved, and the measurement precision is improved. The heating electrode is designed into a ring shape and matched with the disc-shaped ceramic chip, so that the heating temperature is uniform, the heating performance is improved, and the measurement precision is improved.

Drawings

The accompanying drawings, which form a part of the present application, are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the invention and not to limit the invention. In the drawings:

fig. 1 is a structural view of a conventional typical strip-shaped ceramic chip.

Fig. 2 is a structural diagram of the improved nox sensor chip of the present invention.

Fig. 3 is a sectional view a-a of fig. 2.

Fig. 4 is a sectional view B-B of fig. 2.

Fig. 5 is a cross-sectional view C-C of fig. 2.

The device comprises a substrate body, a first electrode, a second electrode, a third electrode, a fourth electrode, a fifth electrode, a ring-shaped heating electrode, a 7-insulating compact alumina protective layer, a 8-reference electrode, a 9-second porous alumina protective layer, a 10-first platinum electrode, a 11-common outer electrode, a 12-first porous alumina protective layer, a 13-second platinum electrode, a 14-measurement platinum electrode, a 15-first pumping oxygen chamber, a 16-first diffusion barrier, a 17-air inlet, a 18-second pumping oxygen chamber, a 19-second diffusion barrier, a 20-reference channel and a 21-lead, wherein the substrate body comprises 1-the second layer of zirconia substrate, 2-the second layer of zirconia substrate, 3-the third layer of zirconia substrate, 4-the fourth layer of zirconia substrate, 5-the fifth layer of zirconia substrate, 6-annular heating electrode, 7-insulating compact alumina protective layer, 8-reference electrode, 9-second porous alumina protective layer, 10-first platinum electrode, 11-common outer electrode, 12-first porous alumina protective layer, 13-second platinum electrode, 14-measurement platinum electrode, 15-first pumping oxygen chamber, 19-second diffusion barrier, 20-reference channel and 21-lead.

Detailed Description

The present invention will be further explained with reference to the drawings and examples.

The improved nitrogen-oxygen sensor chip of the scheme has the following specific implementation steps and effects:

referring to fig. 2, the disc-shaped ceramic chip substrate of the present embodiment is formed by stacking and sintering 1-5 layers of zirconia substrates. Containing NO_XThe exhaust gas enters from the gas inlet 17 (fig. 3) of the second layer zirconia substrate 2 and passes through the first diffusion barrier 16 (fig. 3), and the first diffusion barrier 16 is made of a fine porous alumina material. Because the arc-shaped diffusion channel is adopted, the stress concentration is effectively reduced in the sintering process. Compared with a traditional straight-line channel, the length of the channel is prolonged, tail gas can uniformly enter a first pumping oxygen chamber 15 (figure 3), a loop formed by a first platinum electrode 10 of the first pumping oxygen chamber and a common outer electrode 11 on a first layer of zirconia substrate 1 pumps part of oxygen out of the tail gas out of a substrate, the specific pumped oxygen amount depends on a voltage value set by the loop, and the common outer electrode 11 covers a first porous alumina protective layer 12. Because the tail gas enters uniformly, the amount of the oxygen pumped out by the first pump oxygen chamber is matched with the set voltage value, and NO is simultaneously pumped out_XNO in tail gas₂Decomposed to NO. The tail gas with the reduced oxygen concentration enters the second pump oxygen chamber 18 (figure 3) through the second diffusion barrier 19 (figure 3), and because the second diffusion barrier 19 adopts an arc channel, the stress concentration is effectively reduced in the sintering process, the length of the channel is prolonged compared with the traditional straight channel, and the speed and the flow of the tail gas entering the second pump oxygen chamber 18 are reduced when the tail gas uniformly enters the second pump oxygen chamber 18. The loop formed by the second platinum electrode 13 and the common outer electrode 11 in the second pumping oxygen chamber 18 has enough time to pump all the oxygen remaining in the exhaust gas out of the substrate. The measurement platinum electrode 14 and the common outer electrode 11 in the second pumping oxygen chamber 18 form a loop, gas is subjected to decomposition reaction at high temperature due to the fact that the measurement platinum electrode 14 is mixed with rhodium which is a high catalytic activity material, NO is decomposed into nitrogen and oxygen, the oxygen is pumped out by the loop formed by the measurement platinum electrode 14 and the common outer electrode 11, and NO in automobile exhaust can be obtained by measuring the micro-current value of the loop_XThe concentration value of (c). The second platinum electrode 13 and the measurement platinum electrode 14 are printed in the second oxygen pumping chamber 18, and the function of the chamber reduction is achieved. First, theThe bottom of the three-layer zirconia substrate 3 is printed with a reference electrode 8, and the reference electrode 8 is coated with a second porous alumina protective layer 9. The third layer of zirconia substrate 3 is provided with a reference channel 20 (figure 4) communicated with the outside, the reference electrode 8 is contacted with the outside atmosphere to always ensure stable oxygen partial pressure, and the reference electrode 8 and the platinum electrode 14 form a loop to provide a reference value. An annular heating electrode 6 is printed at the bottom of the fourth zirconia substrate 4, the annular heating electrode 6 is coated with an insulating compact alumina protective layer 7, and the resistance value of a lead 21 (shown in figure 5) is 0.4 times that of the annular heating electrode 6. The temperature of the ceramic matrix reaches about 920 ℃ in a heating short time, and the annular heating electrode 6 is consistent with the wafer ceramic matrix in shape, so that the cavities in the matrix are uniformly distributed, the temperature rise process is stable, the temperature in the matrix is consistent, and the measurement accuracy is guaranteed.

The above-mentioned specific implementation is the preferred embodiment of the present invention, can not be right the utility model discloses the limit, any other does not deviate from the technical scheme of the utility model and the change or other equivalent replacement modes of doing all contain within the scope of protection of the utility model.

Claims

1. An improved nitroxide sensor chip, comprising: the ceramic chip substrate is in a wafer shape and comprises N layers of zirconium oxide substrates which are formed by stacking and sintering, wherein N is not less than 5; the upper surface of the first layer of zirconia substrate is provided with a common outer electrode, the common outer electrode is coated with a first porous alumina protective layer, the second layer of zirconia substrate is sequentially provided with an air inlet, a first pumping oxygen chamber and a second pumping oxygen chamber, the air inlet and the first pumping oxygen chamber are connected, and the first pumping oxygen chamber and the second pumping oxygen chamber are connected through circular-arc channels;

the bottom of the third layer of zirconia substrate is printed with a reference electrode, the reference electrode wraps the second porous alumina protective layer, the third layer of zirconia substrate is provided with a reference channel communicated with the outside, the reference electrode is in contact with the outside atmosphere, the bottom of the fourth layer of zirconia substrate is printed with an annular heating electrode, the annular heating electrode wraps the insulating compact alumina protective layer, and the shape of the annular heating electrode is consistent with that of the ceramic chip substrate.

2. The improved oxynitride sensor chip of claim 1 wherein the second layer of zirconia substrate has a circular arc-shaped first diffusion barrier disposed thereon, the first diffusion barrier has a gas inlet disposed at a head end thereof, the tail end of the first diffusion barrier is connected to the first pumped oxygen chamber, a first platinum electrode is printed in the first pumped oxygen chamber, the other end of the first pumped oxygen chamber is connected to a head end of a circular arc-shaped second diffusion barrier, the tail end of the second diffusion barrier is connected to the second pumped oxygen chamber, and a first platinum electrode and a platinum electrode are printed in the second pumped oxygen chamber.

3. The improved NOx sensor chip of claim 2 wherein the first diffusion barrier is a porous alumina material.

4. The improved nitroxide sensor chip of claim 1, wherein N-5.