Nitrogen oxide sensor single-cavity test system

Abstract

A single-cavity test system for a nitrogen oxide sensor relates to the technical field of nitrogen oxide sensors and comprises a tubular furnace, a quartz tube, an aluminum oxide bracket, a platinum wire, a gas supply device and an arc-shaped flow guide tube, the quartz tube serves as a test cavity, and the test end and the air inlet end of the quartz tube are connected with the exhaust port and the air supply device respectively; the alumina support bears a sensor to be tested and is in sealed connection with the quartz tube through the flexible graphite sealing ring. The platinum wire leads out reference electrode and sensitive electrode signals of the sensor; the gas supply device accurately configures test gases with different concentrations through a buffer tank, a gas inlet pipeline, a valve body and a turbulent flow device; the arc-shaped flow guide pipe divides the test gas into two paths which are respectively blown to the reference electrode and the sensitive electrode, so that the reference electrode and the sensitive electrode are synchronously exposed in the same amount of test gas, and the test precision is improved; a stable and uniform test gas environment is provided for the sensor, and the accuracy and repeatability of a test result are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of nitrogen oxide sensors, and in particular to a single-chamber test system for nitrogen oxide sensors. Background Art

[0002] As is well known, with the rapid development of the automotive industry and the continuous growth of the number of motor vehicles today, motor vehicle exhaust emissions have become one of the main factors of air pollution. According to statistics, the contribution rate of vehicle exhaust to overall air pollution is as high as 65% to 80%, which contains harmful components such as carbon monoxide, unburned hydrocarbons, nitrogen oxides, and particulate matter. The release of these pollutants not only seriously threatens human health but also has a significant impact on the ecological environment. To address this challenge, countries have introduced more stringent vehicle exhaust emission standards aimed at limiting pollutant emissions.

[0003] To achieve the goal of reducing exhaust emissions, real-time monitoring and control technologies have become crucial. The vehicle exhaust control system relies on various sensors such as oxygen sensors, nitrogen oxide sensors, and ammonia sensors, which play a key role in ensuring compliance with emissions standards. In particular, the quality of nitrogen oxide sensors directly affects the accuracy of measurement results. However, the research and development of nitrogen oxide sensors in China are still in its infancy, most products are still in the experimental stage, and there is a lack of effective detection means.

[0004] Traditional NO X The sensor electrode performance test method is usually carried out under room temperature conditions, and the signal terminal is connected to the sensor to obtain data. This method is easily interfered by external climatic conditions and is different from the actual use environment, thus affecting the accuracy of research and quality control. To overcome these problems, the prior art attempts to use a multimeter to evaluate the electrode performance of NO X sensors in a constant temperature and humidity environment, but this method has poor stability and low efficiency, and it is difficult to meet the needs of large-scale applications. Therefore, there is an urgent need in the industry to develop a new test system to more stably and efficiently evaluate the performance of nitrogen oxide sensors. Such a system is of great significance for promoting the development of related technologies. Summary of the Invention

[0005] To overcome the deficiencies in the background art, the present invention discloses a single-chamber test system for nitrogen oxide sensors.

[0006] To achieve the above-mentioned invention purpose, the present invention adopts the following technical solutions:

[0007] A single-chamber test system for nitrogen oxide sensors, comprising:

[0008] A tube furnace for providing a temperature measurement environment of 350°C to 850°C;

[0009] A quartz tube is inserted into the cavity of a tube furnace, and one end of the quartz tube is a test end and the other end is an air inlet end;

[0010] An exhaust port is correspondingly communicated with the part where the quartz tube extends out of the tube body of the tube furnace;

[0011] An alumina support, one end of which is inserted into the quartz tube, and there is a sealed connection between the outer wall of the extended end of the alumina support and the inner wall of the tube orifice of the quartz tube; one end of the alumina support located inside the quartz tube places a nitrogen oxide sensor to be tested, and the reference electrode and the sensitive electrode of the nitrogen oxide sensor to be tested are both exposed inside the quartz tube;

[0012] Platinum wires, there are two platinum wires, which are respectively used for conducting and leading out the wiring ends of the reference electrode and the sensitive electrode of the nitrogen oxide sensor to be tested;

[0013] A gas supply device is installed at the air inlet end of the quartz tube and is used for supplying test gas to the reference electrode and the sensitive electrode;

[0014] Arc-shaped diversion tubes, there are two arc-shaped diversion tubes, and the two arc-shaped diversion tubes are symmetrically arranged inside the quartz tube and are used for dividing the test gas into two paths and blowing them towards the reference electrode and the sensitive electrode respectively.

[0015] Preferably, the gas supply device includes:

[0016] A buffer tank for buffering the test gas;

[0017] An air inlet pipeline, and multiple air inlet pipelines are correspondingly communicated with the buffer tank;

[0018] A first valve body is installed on the air inlet pipeline;

[0019] A flow disturbance device is correspondingly communicated with the air outlet of the buffer tank;

[0020] A second valve body is installed between the buffer tank and the flow disturbance device;

[0021] The flow disturbance device includes:

[0022] Venturi tubes, and multiple Venturi tubes are connected in series;

[0023] A flow disturbance pipe is installed between two adjacent Venturi tubes;

[0024] A flow disturbance net is filled in the flow disturbance pipe, and the flow disturbance net is formed by disorderly curling multiple filaments into a ball and is used for dispersing the test gas and playing a role in blocking the flow.

[0025] Preferably, a spiral blade is arranged in the reduced-diameter section of the Venturi tube.

[0026] Preferably, a connecting flange is arranged at the air outlet end of the flow disturbance device.

[0027] Preferably, a sealing ring is provided between the alumina support and the inner wall of the orifice of the quartz tube.

[0028] Preferably, the sealing ring is a flexible graphite sealing ring, and a corrugated elastic metal support ring is embedded inside the flexible graphite sealing ring.

[0029] Preferably, a thermocouple for temperature measurement is provided inside the quartz tube.

[0030] Preferably, the nitrogen oxide sensor to be measured is bonded to the alumina support by a ceramic adhesive that can withstand heat above 1000 °C.

[0031] Preferably, a necking portion is provided at the air inlet end of the quartz tube.

[0032] Preferably, a one-way valve is installed at the exhaust port.

[0033] Due to the adoption of the above-mentioned technical solution, the present invention has the following beneficial effects:

[0034] (1) The structure of the present invention is simple. The design of the necking portion and the arc-shaped diversion tube of the quartz tube enables the test gas to be directed to blow towards the sensitive electrode and the reference electrode, ensuring that both are synchronously exposed to the same amount of test gas environment, and further improving the test accuracy.

[0035] (2) The gas supply device of the present invention can achieve precise control of the concentration of the test gas through the multi-stage mixing design of the Venturi tube, the turbulence tube and the turbulence net, and the concentration uniformity reaches within ±0.5%. This high-precision gas mixing ability ensures the accurate and reliable test results of the sensor in different concentration NO X environments.

[0036] (3) The present invention further combines the flexible graphite sealing ring with the elastic metal support ring and precisely controls the gas mixing, enabling it to maintain long-term stable test performance in a high-temperature environment. The heat-resistant performance of the sealing ring and the adaptive design of the elastic metal support ring ensure that the system can operate continuously without leakage in a high-temperature environment above 850 °C, thus providing a reliable platform for the long-term stability test of the nitrogen oxide sensor. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 is a schematic structural diagram of the present invention;

[0038] Figure 2 is a schematic structural diagram of the gas supply device;

[0039] Figure 3 is a schematic structural diagram of the sealing ring.

[0040] In the figure: 1, tube furnace; 2, quartz tube; 3, exhaust port; 4, alumina support; 5, platinum wire; 6, gas supply device; 6-1, buffer tank; 6-2, intake pipeline; 6-3, first valve body; 6-4, second valve body; 6-5, Venturi tube; 6-6, spiral blade; 6-7, spoiler tube; 6-8, spoiler net; 6-9, connecting flange; 7, arc-shaped diversion tube; 8, sealing ring; 9, thermocouple; 10, check valve. Specific embodiments

[0041] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0042] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by terms such as "upper" and "lower" is based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship when the product of the present invention is normally placed. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present invention.

[0043] In this application, unless otherwise clearly specified and defined, terms such as "installation", "connection", "connection", "fixation" and other terms should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or integrated; it can be directly connected, or indirectly connected through an intermediate medium, and can be the internal communication of two components or the interaction relationship between two components. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0044] Embodiment 1:

[0045] Combined with the attached Figures 1 to 3 , a single-chamber test system for a nitrogen oxide sensor includes a tube furnace 1, a quartz tube 2, an exhaust port 3, an alumina support 4 and a gas supply device 6. Among them, the tube furnace 1 is the core heating component of the system, which can provide a stable temperature environment of 350 °C to 850 °C to simulate the high-temperature operating conditions of the nitrogen oxide sensor in actual working conditions. The quartz tube 2 is inserted into the cavity of the tube furnace 1. One end of the quartz tube 2 is the test end, and the other end is the intake end. The material of the quartz tube 2 is selected as high-purity quartz glass, because it has excellent high-temperature resistance and chemical stability and can withstand gas corrosion in a high-temperature environment for a long time.

[0046] The test end of the quartz tube 2 is connected to the external environment through the exhaust port 3, which is used to discharge the excess test gas. A one-way valve 10 is installed at the outlet end of the exhaust port 3 to prevent external air from flowing back into the quartz tube 2 and avoid affecting the test accuracy due to changes in oxygen concentration.

[0047] The alumina support 4 is used to carry the nitrogen oxide sensor to be tested. One end of it is inserted into the quartz tube 2, and the nitrogen oxide sensor to be tested is placed at the end of the alumina support 4 inside the quartz tube 2. The reference electrode and the sensitive electrode of the nitrogen oxide sensor to be tested are both exposed inside the quartz tube 2.

[0048] The outer wall of the protruding end of the alumina support 4 and the inner wall of the orifice of the quartz tube 2 are hermetically connected through a sealing ring 8. The sealing ring 8 is made of flexible graphite and is embedded with a corrugated elastic metal support ring to adapt to the deformation of the alumina support 4 and the quartz tube 2 due to thermal expansion and contraction in a high-temperature environment. The flexible graphite sealing ring has the performance of withstanding heat above 1000°C. At the same time, its flexible characteristics can effectively buffer the thermal stress and ensure the long-term stability of the sealing performance. The design of the elastic metal support ring further enhances the mechanical strength of the sealing ring 8, enabling it to still maintain close fit with the alumina support 4 and the quartz tube 2 in a high-temperature environment.

[0049] According to actual needs, the nitrogen oxide sensor to be tested is pasted on the alumina support 4 through a ceramic adhesive that can withstand heat above 1000°C.

[0050] The wiring ends of the sensitive electrode and the reference electrode are respectively led out through platinum wires 5. The platinum wires 5 are made of high-purity platinum metal. Because of its excellent high-temperature resistance and conductivity, it can ensure the stability and accuracy of signal transmission.

[0051] The function of the gas supply device 6 is to accurately configure NO X test gas and achieve uniform mixing of the gas through the flow disturbance device. The gas supply device 6 mainly includes a buffer tank 6-1, an inlet pipeline 6-2, a flow meter, a first valve body 6-3, a second valve body 6-4, a Venturi tube 6-5, a flow disturbance tube 6-7, and a flow disturbance net 6-8.

[0052] The buffer tank 6-1 is connected to a nitrogen gas storage tank, an oxygen gas storage tank, a nitric oxide storage tank, and a nitrogen dioxide storage tank respectively through a plurality of inlet pipelines 6-2. A first valve body 6-3 and a flow meter are installed on each inlet pipeline 6-2. By accurately controlling the opening of the flow meter, quantitative adjustment of the flow rates of different gases can be achieved.

[0053] After the gas enters the buffer tank 6-1, it enters the flow disturbance device through the second valve body 6-4. The flow disturbance device consists of multiple serially connected Venturi tubes 6-5. A spiral blade 6-6 is provided in the reduced-diameter section of the Venturi tube 6-5, which accelerates the gas flow rate through the Bernoulli effect, enabling the gas to achieve preliminary mixing during the high-speed flow process. A flow disturbance tube 6-7 is installed between adjacent Venturi tubes 6-5, and multiple layers of flow disturbance nets 6-8 are filled in the flow disturbance tube 6-7. The flow disturbance net 6-8 is formed by randomly curling stainless steel wires into clusters, and its irregular structure can effectively disperse the gas flow, further enhancing the mixing effect and playing a role in blocking the flow. After multiple stages of flow disturbance, the concentration uniformity of the test gas can reach within ±0.5%, thus ensuring the accuracy of the test results.

[0054] A connecting flange 6-9 is provided at the air outlet end of the flow disturbance device, which is convenient for quickly connecting to the air inlet end of the quartz tube 2 or the extended end of the alumina support 4. The connecting flange 6-9 is made of high-temperature-resistant metal material and is equipped with an O-ring seal to ensure the airtightness of the connection part.

[0055] The air inlet end of the quartz tube 2 is provided with a reduced-diameter part, as shown in the appendix Figure 1 shown. This design can enable the test gas to blow towards the sensitive electrode in a directional manner, thereby improving the test efficiency and reducing the interference of gas diffusion on the test results.

[0056] Furthermore, two arc-shaped diversion tubes 7 are symmetrically provided at the air outlet end of the reduced-diameter part of the quartz tube 2. The two arc-shaped diversion tubes 7 are used to divide the test gas into two paths and blow them towards the reference electrode and the sensitive electrode respectively, so as to ensure that the reference electrode and the sensitive electrode can be synchronously exposed to the same amount of test gas environment, further improving the accuracy of the test results.

[0057] Furthermore, a thermocouple 9 is provided in the quartz tube 2 for real-time monitoring of the internal environment temperature of the tube. The thermocouple 9 is a K-type thermocouple, and its temperature measurement range covers -200°C to 1370°C, which can meet the accurate temperature measurement requirements of the system in the temperature range of 350°C to 850°C. The signal of the thermocouple 9 is led out through a shielded cable and connected to a temperature controller to realize the closed-loop regulation of the heating power of the tube furnace 1. The temperature controller adopts a PID algorithm, which can control the temperature fluctuation within ±1°C, thereby providing a stable high-temperature environment for the test.

[0058] Furthermore, the test gas in the quartz tube 2 is discharged through the exhaust port 3. The exhaust port 3 is communicated with the external exhaust system and is equipped with a flow regulating valve for controlling the exhaust speed to avoid the formation of negative pressure in the quartz tube 2 due to too fast exhaust.

[0059] The parts not detailed in the present invention are prior arts. For those skilled in the art, it is obvious that the present invention is not limited to the details of the above-mentioned exemplary embodiments, and can be implemented in other specific forms without departing from the spirit or basic characteristics of the present invention. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-restrictive, aiming to include all changes falling within the meaning and scope of equivalent elements in the present invention.

Claims

1. A single-chamber test system for a nitrogen oxide sensor, characterized in that, Comprising: A tube furnace (1) for providing a temperature measurement environment of 350°C to 850°C; A quartz tube (2) inserted into the cavity of the tube furnace (1), with one end of the quartz tube (2) being the test end and the other end being the air inlet end; An exhaust port (3) corresponding to and communicating with the part of the quartz tube (2) extending out of the body of the tube furnace (1); An alumina support (4) with one end inserted into the quartz tube (2), and a sealed connection between the outer wall of the extending end of the alumina support (4) and the inner wall of the tube orifice of the quartz tube (2); One end of the alumina support (4) located inside the quartz tube (2) places a nitrogen oxide sensor to be tested, and the reference electrode and the sensitive electrode of the nitrogen oxide sensor to be tested are both exposed inside the quartz tube (2); Platinum wires (5), two platinum wires (5) respectively used for conducting and leading out the wiring ends of the reference electrode and the sensitive electrode of the nitrogen oxide sensor to be tested; A gas supply device (6) installed at the air inlet end of the quartz tube (2) for supplying test gas to the reference electrode and the sensitive electrode; Arc-shaped diversion tubes (7), two arc-shaped diversion tubes (7) symmetrically arranged inside the quartz tube (2) for dividing the test gas into two paths and blowing them towards the reference electrode and the sensitive electrode respectively.

2. The nitrogen oxide sensor single-chamber test system according to claim 1, wherein, The gas supply device (6) includes: A buffer tank (6-1) for buffering the test gas; Inlet gas pipelines (6-2), multiple inlet gas pipelines (6-2) corresponding to and communicating with the buffer tank (6-1); A first valve body (6-3) installed on the inlet gas pipeline (6-2); A flow disturbance device corresponding to and communicating with the air outlet of the buffer tank (6-1); A second valve body (6-4) installed between the buffer tank (6-1) and the flow disturbance device; The flow disturbance device includes: Venturi tubes (6-5), multiple Venturi tubes (6-5) connected in series; A flow disturbance tube (6-7) installed between two adjacent Venturi tubes (6-5); A flow disturbance net (6-8) filled inside the flow disturbance tube (6-7), the flow disturbance net (6-8) formed by randomly curling multiple filaments into clusters for dispersing the test gas and playing a flow blocking role.

3. The single-chamber test system for nitrogen oxide sensors according to claim 2, wherein: A spiral blade (6-6) is provided inside the reduced-diameter section of the Venturi tube (6-5).

4. The single-chamber test system for nitrogen oxide sensors according to claim 1, wherein: A connecting flange (6-9) is provided at the air outlet end of the flow disturbance device.

5. The single-chamber test system for nitrogen oxide sensors according to claim 1, wherein: A sealing ring (8) is provided between the alumina support (4) and the inner wall of the tube orifice of the quartz tube (2).

6. The single-chamber test system for nitrogen oxide sensors according to claim 5, wherein: The sealing ring (8) is a flexible graphite sealing ring, and a wavy elastic metal support ring is embedded inside the flexible graphite sealing ring.

7. The single-chamber test system for nitrogen oxide sensors according to claim 1, wherein: A thermocouple (9) for temperature measurement is provided inside the quartz tube (2).

8. The single-chamber test system for nitrogen oxide sensors according to claim 1, wherein: The nitrogen oxide sensor to be measured is bonded to an alumina bracket (4) through a ceramic adhesive that can withstand heat above 1000 °C.

9. The single-chamber test system for a nitrogen oxide sensor according to claim 1, wherein: A necking part is provided at the air inlet end of the quartz tube (2).

10. The single-chamber test system for a nitrogen oxide sensor according to claim 1, wherein: A check valve (10) is installed at the exhaust port (3).

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