A NO x Sensor chip performance analysis method and system

Abstract

The present invention discloses a NOx sensor chip performance analysis method and system, including: placing the sensor chip in an air atmosphere, and performing electrode activation on the three working circuits of the chip respectively through a cyclic voltammetry test. The sensor chip is placed in an air atmosphere, and a cyclic voltammetry test is carried out between a common electrode and a first working electrode to determine the main pump working voltage E0; a cyclic voltammetry test is carried out between the common electrode and the second working electrode to determine the auxiliary pump working voltage E1; a cyclic voltammetry test is carried out between the common electrode and the test electrode to determine the test voltage E2. The chip is placed in a NOx environment, and the main pump working voltage E0 is applied to the first working circuit to form the main pump working current Ip0; the auxiliary pump working voltage E1 is applied to the second working circuit to form the auxiliary pump working current Ip1; the main pump working voltage E2 is applied to the test circuit to form the test current Ip2. The chip is judged to be qualified when the effective current signals formed by the three circuits can all meet the design requirements of the sensor chip.

Description

Technical Field

[0001] The invention relates to a NOx sensor chip performance analysis method and system, belonging to the technical field of gas sensors. Background Art

[0002] As a means of detecting NOx in exhaust gas, automotive NOx sensors can monitor high-temperature exhaust gas in a timely and effective manner. As the core component of NOx performance detection, the performance of the sensor chip directly determines the detection capability of the sensor. When the sensor chip is working, it is composed of three working circuits, and each working circuit forms a three-electrode working system including a working electrode, a counter electrode, and a reference electrode. When the chip is working, the sensor detects NOx in the order of the first circuit, the second circuit, and the test circuit. However, due to limitations in structure and process level, automotive NOx gas sensors are currently monopolized by foreign manufacturers, and there is a lack of measurement and evaluation methods and processes for the electrical performance of the sensor. In order to meet the needs of sensor performance evaluation and analysis, it is necessary to establish reasonable detection methods and processes to guide sensor research. Summary of the invention

[0003] The object of the present invention is to provide a NOx sensor chip performance analysis method, which can enable the sensor chip to quickly enter the optimal working state and can determine different optimal working conditions for different chips, so as to measure and evaluate the performance of automotive ceramic NOx sensor chips.

[0004] Another object of the present invention is to provide a NOx sensor chip performance detection system suitable for the method.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] A method for analyzing performance of a NOx sensor chip, characterized in that it comprises the following steps:

[0007] (1) placing the sensor chip in air, wherein the NOx content in the air atmosphere is 0; performing a cyclic voltammetry test between the common electrode and the first working electrode, the circuit forms a V-i0 curve, and measuring the voltage value E0 corresponding to the saturation current i0 as the main pump working voltage; performing a cyclic voltammetry test between the common electrode and the second working electrode, the circuit forms a V-i1 curve, and measuring the voltage E1 corresponding to the saturation current i1 as the auxiliary pump working voltage; performing a cyclic voltammetry test between the common electrode and the test electrode, the circuit forms a V-i2 curve, and measuring the voltage E2 corresponding to the saturation current i2 as the test voltage;

[0008] (2) The sensor chip is placed in an air atmosphere for operation, and a main pump working voltage E0, an auxiliary pump working voltage E1, and a test voltage E2 are applied between the common electrode and the first working electrode, the second working electrode, and the test electrode, respectively, to measure the main pump working current Ip0, the auxiliary pump working current Ip1, and the test current Ip2;

[0009] (3) The sensor chip is placed in a NOx atmosphere, in which the oxygen content is 0 and the NO content is 1000 ppm; the main pump working voltage E0, the auxiliary pump working voltage E1, and the test voltage E2 are applied between the common electrode and the first working electrode, the second working electrode, and the test electrode, respectively, and the main pump working current Ip0, the auxiliary pump working current Ip1, and the test current Ip2 are measured;

[0010] (4) The chip is judged to be qualified when the main pump working voltage E0, auxiliary pump working voltage E1, test voltage E2, main pump working current Ip0, auxiliary pump working current Ip1, and test current Ip2 simultaneously meet the chip design requirements; otherwise, the chip is judged to be unqualified.

[0011] Furthermore, in the step (1), the sensor chip is first placed in an air atmosphere, and activation tests are performed on the three circuits for 0.5 hours, and after activation, the main pump working voltage E0, the auxiliary pump working voltage E1, and the test voltage E2 are measured. The activation test adopts cyclic voltammetry, the test voltage is -0.8 to 0.8V, the scan rate is 0.1V / s, and the number of scans is 100.

[0012] Furthermore, in the step (1), the sensor chip is placed in an air atmosphere, and the chip is heated at a high temperature to a temperature of 650 to 850°C.

[0013] Furthermore, when the sensor chip is tested, air and NOx standard gas are introduced alternately, and the working current is monitored all the time, that is, the steps (2) and (3) are taken as one cycle, and multiple cycles are repeated, and the average values ​​of the working currents obtained in the steps (2) and (3) are calculated respectively. The oxygen content of the NOx standard gas is 0, and the NO content is 1000ppm. By alternately introducing air and NOx standard gas, the current change trend of the sensor in different atmospheres can be clearly observed, and a dynamic response curve can be obtained. Preferably, the process is repeated for 2 to 4 cycles, and the average value of the working current obtained is taken.

[0014] Furthermore, after the sensor chip is activated, cyclic voltammetry tests are carried out in the first working circuit, the second working circuit and the test circuit in an air atmosphere, respectively, with a test voltage of -0.8 to 0.8 V. At a voltage of -0.5 V, the chip is qualified if the working current is within the following range: the main pump working current Ip0 ranges from 1 to 6 mA, the auxiliary pump working current Ip1 ranges from 0.1 to 3 mA, and the test current Ip2 ranges from 0.1 to 3 mA.

[0015] Furthermore, after the cyclic voltammetry test, the sensor is placed in a NOx atmosphere, and the main pump working voltage E0, the auxiliary pump working voltage E1, and the test voltage E2 are applied. The chip is qualified if the working current is within the following range: the main pump working current Ip0 ranges from 0 to 4 mA, the auxiliary pump working current Ip1 ranges from 0 to 100 μA, and the test current Ip2 ranges from 0 to 100 μA.

[0016] Accordingly, the NOx sensor chip performance detection system provided by the present invention includes the following three parts:

[0017] A gas distribution device is used to dynamically provide air atmosphere and NOx atmosphere; the NOx content in the air atmosphere is 0; the oxygen content in the NOx atmosphere is 0, and the NOx content is 1000ppm; the gas distribution flow rate is 0 to 1000mL / min;

[0018] The detection chamber is used to provide stable heating and sealing cavity for the sensor chip; the cavity is heated to a temperature range of 650-850°C; the sealed cavity is connected to the gas distribution system;

[0019] The electronic control unit is connected to the sensor chip, and is used to output voltage signals and control the chip operation, and at the same time extract the current signal when the chip is working to determine whether the performance of the chip to be tested meets the design requirements; the electronic control unit includes a host system and is connected to the gas distribution device to control the detection atmosphere.

[0020] The advantages of the present invention are:

[0021] 1. The present invention relates to a sensor chip performance analysis process, including a cyclic voltammetry activation test. By performing cyclic voltammetry tests on three working circuits respectively, the voltage and current signals of the circuits can be quickly stabilized, so that the sensor chip can quickly enter the best working state.

[0022] 2. The present invention relates to a sensor chip performance analysis process, which includes determining the main pump working voltage E0, the auxiliary pump working voltage E1, and the test voltage E2 through cyclic voltammetry testing, and can specifically determine the optimal working conditions.

[0023] 3. The test system involved in the present invention can test chips without heating electrodes, and the test system can test non-standard samples.

[0024] 4. The present invention relates to the testing of sensor chips in air and NOx atmospheres. The test results are comparative and provide a variety of chip performance analysis indicators and single electrode working performance analysis indicators. By comparing the working current range of the V-i0, V-i1, and V-i2 curves in the air, it can be determined whether the single electrode can work normally. When the V range is 0 to -0.8V, the i0 range is 1 to 6mA, the i1 range is 0.1 to 3mA; the i2 range is 0.1 to 3mA, each circuit is connected, and the chip is qualified. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 Schematic diagram of the NOx sensor chip structure and working principle.

[0026] Figure 2 Schematic diagram of the NOx sensor chip detection system.

[0027] Figure 3 Schematic diagram of the process of NOx sensor chip performance analysis method.

[0028] Figure 4 These are the V-i0, V-i1, and V-i2 curves of the NOx sensor chip. DETAILED DESCRIPTION

[0029] The present invention will be further described below by way of examples.

[0030] NOx sensor chip structure and working principle:

[0031] The sensor chip has a three-chamber structure, such as Figure 1 Specific working principle: When working, the reference electrode is in contact with the air; the main pump working voltage E0, the auxiliary pump working voltage E1, and the test voltage E2 are applied respectively, and the applied voltage is stable through feedback (V0, V1, V2, Vref); when the gas is introduced, the main pump working circuit and the auxiliary pump working circuit complete the decomposition of impurity gas and oxygen, and finally the gas composition at the test electrode is NOx; NOx gas reacts with the active components in the test electrode to decompose into oxygen and nitrogen, and the pump current Ip2 generated by the decomposition to produce oxygen is detected to monitor the NOx content.

[0032] Example 1

[0033] A NOx sensor chip performance detection system, specifically Figure 2 As shown, it includes the following three parts:

[0034] A gas distribution device is used to dynamically provide air atmosphere and NOx atmosphere; the NOx content in the air atmosphere is 0; the oxygen content in the NOx atmosphere is 0, and the NOx content is 1000ppm; the gas distribution flow rate is 0 to 1000mL / min;

[0035] The detection chamber is used to provide a stable heating and sealing cavity for the sensor chip; the heating temperature range of the heating cavity is 650-850°C; the sealed cavity is connected to the gas distribution system;

[0036] The electronic control unit is connected to the sensor chip, and is used to output voltage signals and control the chip operation, and at the same time extract the current signal when the chip is working to determine whether the performance of the chip to be tested meets the design requirements; the electronic control unit includes a host system and is connected to the gas distribution device to control the detection atmosphere.

[0037] like Figure 3 As shown, a NOx sensor chip performance analysis method is as follows:

[0038] 1. Connect the chip to be tested to the electronic control unit and place it in the test chamber;

[0039] 2. Connect the test chamber to the gas distribution device and control the gas flow rate to 500mL / min;

[0040] 3. Place the sensor chip in an air atmosphere and heat it to 750°C;

[0041] 4. Through the electronic control unit, a cyclic voltammetry test is performed between the common electrode and the first working electrode for 100 cycles; a cyclic voltammetry test is performed between the common electrode and the second working electrode for 100 cycles; a cyclic voltammetry test is performed between the common electrode and the test electrode for 100 cycles;

[0042] 5. Through the electronic control unit, a cyclic voltammetry test is performed in the first circuit to measure the V-i0 curve, and the saturation current i0 corresponds to the voltage value E0 as the main pump working voltage; a cyclic voltammetry test is performed in the second circuit to measure the V-i1 curve, and the saturation current i1 corresponds to the voltage E1 as the auxiliary pump working voltage; a cyclic voltammetry test is performed in the test circuit to measure the V-i2 curve, and the saturation current i2 corresponds to the voltage E2 as the test voltage. Figure 4 As shown, E0 is 0.3~0.4V, E1 is 0.35~0.45V, and E2 is 0.4~0.5V.

[0043] 6. Place the sensor chip in an air atmosphere, apply the main pump working voltage E0, auxiliary pump working voltage E1, and test voltage E2 between the common electrode and the first working electrode, the second working electrode, and the test electrode, respectively, and measure the main pump working current Ip0, auxiliary pump working current Ip1, and test current Ip2. Among them, Ip0 is 1-6mA, Ip1 is 0.1-3mA, and Ip2 is 0.1-100μA.

[0044] 7. NOx atmosphere, where the oxygen content is 0 and the NO content is 1000ppm (NOx standard gas); place the sensor chip in the NOx atmosphere, apply the main pump working voltage E0, the auxiliary pump working voltage E1, and the test voltage E2 between the common electrode and the first working electrode, the second working electrode, and the test electrode, respectively, and measure the main pump working current Ip0, the auxiliary pump working current Ip1, and the test current Ip2. When Ip0 is 0-4mA, Ip1 is 0-100μA, and Ip2 is 0-100μA, the chip is qualified.

[0045] 8. When testing the sensor chip, air and NOx standard gas are introduced alternately and the working current is monitored all the time.

[0046] 9. When the chip is working, the main pump working voltage E0, the auxiliary pump working voltage E1, the test voltage E2, the main pump working current Ip0, the auxiliary pump working current Ip1, and the test current Ip2 all meet the design requirements, the chip is judged to be qualified, otherwise it is judged to be unqualified.

[0047] 10. In air atmosphere, cyclic voltammetry test is carried out in the first working circuit, the second working circuit and the test circuit. The test voltage is -0.8~0.8V. When the voltage is -0.5V, the chip is qualified if the working current is within the following range: the main pump working current Ip0 range is 1~6mA, the auxiliary pump working current Ip1 range is 0.1~3mA, and the test current Ip2 range is 0.1~100μA.

[0048] 11. In NOx atmosphere, apply the main pump working voltage E0, auxiliary pump working voltage E1 and test voltage E2 respectively. The chip is qualified if the working current is within the following range: the main pump working current Ip0 ranges from 0 to 4mA, the auxiliary pump working current Ip1 ranges from 0 to 100μA, and the test current Ip2 ranges from 0 to 100μA.

Claims

1. A NOx sensor chip performance analysis method, characterized in that: The following steps are involved: (1) The sensor chip is placed in an air atmosphere in which the NOx content is 0; a cyclic voltammetry test is performed between the common electrode and the first working electrode, the circuit forms a V-i0 curve, and the voltage value E0 corresponding to the saturation current i0 is measured as the main pump working voltage; a cyclic voltammetry test is performed between the common electrode and the second working electrode, the circuit forms a V-i1 curve, and the voltage E1 corresponding to the saturation current i1 is measured as the auxiliary pump working voltage; a cyclic voltammetry test is performed between the common electrode and the test electrode, the circuit forms a V-i2 curve, and the voltage E2 corresponding to the saturation current i2 is measured as the test voltage; (2) The sensor chip is placed in an air atmosphere for operation, and the main pump working voltage E0, the auxiliary pump working voltage E1, and the test voltage E2 are applied between the common electrode and the first working electrode, the second working electrode, and the test electrode, respectively, and the main pump working current Ip0, the auxiliary pump working current Ip1, and the test current Ip2 are measured; (3) The sensor chip is placed in a NOx atmosphere, in which the oxygen content is 0 and the NOx content is 1000 ppm; the main pump working voltage E0, the auxiliary pump working voltage E1, and the test voltage E2 are applied between the common electrode and the first working electrode, the second working electrode, and the test electrode, respectively, and the main pump working current Ip0, the auxiliary pump working current Ip1, and the test current Ip2 are measured; (4) Apply the main pump working voltage E0, the auxiliary pump working voltage E1, and the test voltage E2. The chip is qualified if the working current is within the following range: the main pump working current Ip0 range is 0~4 mA, the auxiliary pump working current Ip1 range is 0~100 μA, and the test current Ip2 range is 0~100 μA. Otherwise, it is judged as unqualified.

2. The NOx sensor chip performance analysis method according to claim 1, characterized in that: In the step (1), the sensor chip is first placed in an air atmosphere, and a 0.5-hour cyclic voltammetry activation test is performed on the three circuits respectively. After activation, the main pump working voltage E0, the auxiliary pump working voltage E1, and the test voltage E2 are measured.

3. The NOx sensor chip performance analysis method according to claim 2, characterized in that: In the step (1), the sensor chip is placed in an air atmosphere, and the chip is heated at a high temperature to a temperature of 650-850°C.

4. The NOx sensor chip performance analysis method according to claim 1, characterized in that: When testing the sensor chip, air and NOx standard gas are introduced alternately, and the working current is monitored all the time, that is, taking step (2) and step (3) as one cycle, repeating multiple cycles, and calculating the average values ​​of the working currents obtained in step (2) and step (3), respectively.

5. The NOx sensor chip performance analysis method according to claim 4, characterized in that: Repeat 2 to 4 cycles.

6. A NOx sensor chip performance detection system applicable to the method described in any one of claims 1 to 5, characterized in that: It includes the following three parts: A gas distribution device, used for dynamically providing air atmosphere and NOx atmosphere; the NOx content in the air atmosphere is 0; the oxygen content in the NOx atmosphere is 0, and the NOx content is 1000 ppm; the gas distribution flow rate is 0~1000mL / min; The detection chamber is used to provide stable heating and sealing cavity for the sensor chip; the cavity heating temperature range is 650~850℃; the sealed cavity is connected to the gas distribution system; The electronic control unit is connected to the sensor chip to output voltage signals and control the chip operation, and to extract the current signal when the chip is working to determine whether the performance of the chip to be tested meets the design requirements; The electronic control unit includes a host system and is connected to a gas distribution device to control the detection atmosphere.

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