NOx sensor chip performance test feedback method

Abstract

The application discloses a kind of NOx sensor chip performance test feedback methods, realize the automatic detection of NOx sensor chip for exhaust detection.Heat sensor and pass into air, by applying voltage to three working circuits, and determine the working voltage, working current of each working circuit, determine the static working performance of sensor;By setting voltage adjustment formula and parameters in the controller, ensure that the sensor chip is in normal working state, realize the automatic detection of NO of sensor in different gas environment, and determine the response time of sensor chip, evaluate the dynamic working performance of NOx sensor chip.The application has the advantages of high efficiency, non-destructive, can realize the automatic detection of sensor chip.

Description

Technical Field

[0001] This invention relates to a NOx sensor chip performance testing feedback method, belonging to the field of gas sensor technology. Background Technology

[0002] With the release of the National VI emission standards for motor vehicles and the increasing societal demands for environmental protection, the monitoring and emission of pollutants from vehicle exhaust have received growing attention. The main harmful components of vehicle exhaust are nitrogen oxides, incompletely combusted hydrocarbons, and particulate matter. To achieve stringent emission standards for exhaust gases, real-time and accurate measurement of the types and amounts of pollutants in the exhaust is crucial. The quality of the NOx sensor directly determines the accuracy of exhaust gas testing. However, the development of related sensors in China has been immature in recent years, especially in sensor detection, where a unified detection method and approach are lacking. A NOx sensor is a complex system with three working loops. During operation, three different voltages need to be applied simultaneously, and seven parameters, including the working voltage and current, need to be measured. The loops influence each other, collectively determining the NOx content in the complex exhaust gas. Currently, commonly used detection methods mainly target the operation of a single loop, and these methods may cause irreversible damage to the chip. To better measure the comprehensive detection performance of sensor chips, there is an urgent need to develop a simple, non-destructive, and automated testing and feedback system. Summary of the Invention

[0003] The purpose of this invention is to provide a NOx sensor chip performance testing feedback method, which can provide an efficient, labor-saving, non-destructive, simple and automated testing method for comprehensive performance evaluation of sensor chips.

[0004] To achieve the above objectives, the present invention adopts the following technical solution:

[0005] A method for testing and providing feedback on the performance of a NOx sensor chip includes the following steps:

[0006] (1) Heat the sensor chip to 700~800℃ and place the chip in an oxygen environment with an oxygen content of 21% and the remainder being nitrogen; apply voltages E0_0, E1_0 and E2_0 to the first working circuit, the second working circuit and the third working circuit of the chip respectively, and test the working voltages V0_0, V1_0 and V2_0 and the working currents Ip0_0, Ip1_0 and Ip2_0 of the first working circuit, the second working circuit and the third working circuit, and test the working voltage Vref_0 between the external electrode and the reference electrode;

[0007] (2) Place the sensor chip in a nitrogen environment and test the working voltage V0 of the first working circuit and the working current Ip1 of the second working circuit. Adjust the applied voltage of the first working circuit multiple times: E0_n = E0_n-1 + K1×(V0_n-V0_n-1) + K2×(Vref_n-Vref_n-1) + K3×(Ip_n-7×10 -6 ), until Ip1=4~10μA; adjust the voltage applied to the second working circuit E1_n=E1_n-1+K4(V1_n-V1_n-1) until V1=400mV~450mV; adjust the voltage applied to the third working circuit E2=E1+10mV;

[0008] (3) Fix the parameters K1, K2, K3, and K4, move the sensor chip into the NOx environment, where the NO content is 300 ppm, the oxygen content is 2%, and the rest is nitrogen; apply E0, E1, and E2, record the change of Ip2 from the nitrogen environment to the NOx environment, and determine the response time t required for Ip2 to change from 10% to 90%.

[0009] Furthermore, in step (1), V0_0=300~350mV, V1_0=400~450mV, V2_0=410~460mV, Vref_0=0~100mV, Ip0_0=1~6mA, Ip1_0=4~10μA, and Ip2_0=0.1~0.5μA, indicating that the static sensing performance of the sensor is qualified.

[0010] Furthermore, in step (2), K1 = 0.1~50, K2 = 0.5~10, K3 = 500~5000, and K4 = 0.1~1.5.

[0011] Furthermore, in step (3), the sensor performance is qualified when the response time t = 2~4s.

[0012] The advantages of this invention are:

[0013] 1. The NOx sensor chip performance testing feedback method of the present invention is an automated process. By inputting the measurement ranges of Ip1, V1, and V2 into the main controller and setting the adjustment formulas of E0, E1, and E2, the automatic testing function of the NOx sensor chip can be realized, and the change of the working current of Ip2 when the sensor chip works continuously in different atmospheres can be recorded.

[0014] 2. The NOx sensor chip performance testing feedback method of the present invention can obtain the changing trend of the Ip2 operating current of the sensor chip in a changing atmosphere, calculate the response time of the chip during operation, and evaluate the dynamic operating performance of the NOx sensor chip.

[0015] 3. The NOx sensor chip performance testing feedback method of the present invention can effectively avoid sensor damage caused by excessive loading voltage, improve the sensor chip performance detection efficiency, and reduce the sensor damage rate. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the device involved in the NOx sensor chip performance testing feedback method of the present invention.

[0017] Figure 2 This is a schematic diagram of the working principle of a NOx sensor chip. Detailed Implementation

[0018] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0019] Figure 1 In this embodiment, the device involved in the NOx sensor chip performance testing feedback method consists of a gas distribution system 1, a test chamber 2, a voltage control unit 3, a voltage testing unit 4, a current testing power supply 5, a main controller 6, a computer 7, and a sensor chip 8.

[0020] The gas distribution system 1 is connected to the test chamber 2 and is used to control the test environment of different sensor chips 8. The test chamber 2 has a heating function. The voltage control unit 3 is connected to the main controller 6, and its output voltage positive and negative terminals are connected to the external electrode, the negative terminal of the first working circuit, the negative terminal of the second working circuit, and the negative terminal of the third working circuit of the sensor chip 8, respectively, to receive the voltage E0, E1, and E2 applied to the sensor chip 8 by the main controller 6. The voltage testing unit 4 is connected to the main controller 6 and is used to measure the working voltages V0, V1, V2, and Vref of the first working circuit, the second working circuit, the third working circuit, and the circuit formed by the external electrode and the reference electrode of the sensor chip 8. The current testing unit is connected to the main controller 6 and is used to measure the working currents Ip0, Ip1, and Ip2 of the first working circuit, the second working circuit, and the third working circuit of the sensor chip 8. The main controller 6 is connected to the computer 7 for parameter setting and data reading.

[0021] NOx sensor chip structure and working principle:

[0022] The sensor chip has a three-chamber structure, such as Figure 2The sensor consists of three working circuits, each forming a three-electrode system including a working electrode, a counter electrode, and a reference electrode. During operation, the sensor chip detects NOx in the order of the first working circuit, the second working circuit, and the third working circuit (test circuit). Specifically, during operation, the main pump operating voltage E0, the auxiliary pump operating voltage E1, and the test voltage E2 are applied. Feedback (V0, V1, V2, Vref) ensures stable applied voltages, while the main pump operating current Ip0, the auxiliary pump operating current Ip1, and the test current Ip2 are recorded. When gas is introduced, the first and second working circuits decompose impurity gases such as NO2, CO, and oxygen, resulting in NO as the final gas composition in the third working circuit. The NO gas reacts with the active component in the test electrode, decomposing into oxygen and nitrogen. The NOx content is monitored by detecting the pump current Ip2, which generates oxygen during decomposition.

[0023] Example

[0024] A method for testing and providing feedback on the performance of a NOx sensor chip is as follows:

[0025] 1. Sensor Static Comprehensive Performance Evaluation

[0026] (1) Heat the sensor to 750°C and introduce nitrogen gas with a content of 21% O2;

[0027] (2) Apply E0, E1, and E2 to make V0 = 300mV, V1 = 450mV, V2 = 460mV, Vref = 0mV, and Ip1 = 4~10μA;

[0028] (3) Record the values ​​of Ip0, Ip1, and Ip2 at this time.

[0029] (4) When Ip0 is 1~6mA and Ip2 is 0.1~0.5μA, the static performance of the sensor is qualified.

[0030] 2. Measurement of sensor adjustment constant

[0031] (1) Input in the main controller: E0_n = E0_n-1 + K1 × (V0_n - V0_n-1) + K2 × (Vref_n - Vref_n-1) + K3 × (Ip_n - 7 × 10) -6 E1 = E1_n-1 + K4(V1_n - V1_n-1), E2 = E1 + 10mV adjustment formula, setting K1, K2, K3, K4 as free numbers, where K1 = 0.1~50, K2 = 0.5~10, K3 = 500~5000, K4 = 0.1~1.5;

[0032] (2) Replace the nitrogen gas with nitrogen gas containing 21% O2 as described above;

[0033] (3) Adjust the values ​​of K1, K2, K3 and K4 so that the sensor reaches Ip1=4~10μA, V0=400mV~450mV and V1=410mV~460mV within 20s;

[0034] (4) Record K1', K2', K3', K4' and input the above formula.

[0035] 3. Dynamic Comprehensive Performance Evaluation of Sensors

[0036] (1) Main controller input E0_n=E0_n-1+K1'×(V0_n-V0_n-1)+K2'×(Vref_n-Vref_n-1)+K3'×(Ip_n-7×10 -6 E1 = E1_n-1 + K4'(V1_n - V1_n-1), E2 = E1 + 10mV adjustment formula;

[0037] (2) Replace the above nitrogen gas with a NOx atmosphere, wherein the NO content in the NOx atmosphere is 300 ppm, the oxygen content is 2%, and the remainder is nitrogen gas;

[0038] (3) Record the trend of Ip2 changes;

[0039] (4) Calculate the response time t required for Ip2 to change from 10% to 90% of its final value. When t = 2~4s, the sensor is qualified.

Claims

1. A NOx sensor chip performance testing feedback method, characterized in that, Includes the following steps: (1) Heat the sensor chip to 700~800℃ and place the chip in an oxygen environment with an oxygen content of 21% and the remainder being nitrogen; apply voltages E0_0, E1_0 and E2_0 to the first working circuit, the second working circuit and the third working circuit of the chip respectively, and test the working voltages V0_0, V1_0 and V2_0 and the working currents Ip0_0, Ip1_0 and Ip2_0 of the first working circuit, the second working circuit and the third working circuit, and test the working voltage Vref_0 between the external electrode and the reference electrode; (2) Place the sensor chip in a nitrogen environment and test the working voltage V0 of the first working circuit and the working current Ip1 of the second working circuit. Adjust the applied voltage of the first working circuit multiple times: E0_n = E0_n-1 + K1×(V0_n-V0_n-1) + K2×(Vref_n-Vref_n-1) + K3×(Ip_n-7×10 -6 ), until Ip1=4~10μA; adjust the voltage applied to the second working circuit E1_n=E1_n-1+K4(V1_n-V1_n-1) until V1=400mV~450mV; adjust the voltage applied to the third working circuit E2=E1+10mV; (3) Fix parameters K1, K2, K3, and K4, and move the sensor chip into a NOx environment. In this NOx environment, the NO content is 300 ppm, the oxygen content is 2%, and the rest is nitrogen. Apply E0, E1, and E2 to the sensor chip, record the change of Ip2 from the nitrogen environment to the NOx environment, and determine the response time t required for Ip2 to change from 10% to 90%. Where E0 represents the applied voltage of the first working circuit; E0_n represents the applied voltage of the first working circuit during the nth feedback cycle; and E0_n-1 represents the applied voltage of the first working circuit during the (n-1)th feedback cycle. E1 represents the applied voltage of the second working circuit; E1_n represents the applied voltage of the second working circuit during the nth feedback cycle; E1_n-1 represents the applied voltage of the second working circuit during the (n-1)th feedback cycle. E2 represents the applied voltage of the third working circuit; V0_n represents the operating voltage of the first working circuit during the nth feedback cycle; V0_n-1 represents the operating voltage of the first working circuit during the (n-1)th feedback cycle. V1 represents the operating voltage of the second working circuit; V1_n represents the operating voltage of the second working circuit during the nth feedback cycle; V1_n-1 represents the operating voltage of the second working circuit during the (n-1)th feedback cycle. Vref_n represents the operating voltage at which the external electrode and the reference electrode form a circuit during the nth feedback cycle; Vref_n-1 represents the operating voltage at which the external electrode and the reference electrode form a circuit during the (n-1)th feedback cycle. Ip1 represents the operating current of the second working circuit; Ip_n represents the operating current of the second working loop during the nth feedback cycle; Ip2 represents the operating current of the third working circuit; K1 represents the working coefficient of the working voltage iteration difference of the first working circuit; K2 represents the working coefficient of the working voltage iteration difference of the circuit formed by the external electrode and the reference electrode; K3 represents the working coefficient of the working current iteration difference of the second working circuit; K4 represents the working coefficient of the working voltage iteration difference of the second circuit.

2. The NOx sensor chip performance testing feedback method according to claim 1, characterized in that, In step (1), V0_0 = 300~350mV, V1_0 = 400~450mV, V2_0 = 410~460mV, Vref_0 = 0~100mV, Ip0_0 = 1~6mA, Ip1_0 = 4~10μA, Ip2_0 = 0.1~0.5μA, and the static sensing performance of the sensor is qualified.

3. The NOx sensor chip performance testing feedback method according to claim 1, characterized in that, In step (2), K1 = 0.1~50, K2 = 0.5~10, K3 = 500~5000, and K4 = 0.1~1.

5.

4. The NOx sensor chip performance testing feedback method according to claim 1, characterized in that, In step (3), the sensor performance is qualified when the response time t = 2~4s.

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