Method and system for measuring oxygen storage / release rate of automobile exhaust three-way catalyst

Abstract

The invention discloses a method and system for measuring the oxygen storage / release rate of an automobile exhaust three-way catalyst, and the method achieves the testing of the oxygen storage / release rate of the automobile exhaust purification three-way catalyst on a catalytic performance evaluation device, and controls the air-fuel ratio of an engine to be alternately switched from rich combustion to lean combustion. The oxygen storage rate is measured according to the ratio of the time difference of the post-oxygen voltage from the high change point to the first horizontal point to the voltage difference; the oxygen release rate is measured according to the ratio of the time difference of the post-oxygen voltage rising from the low position to the change point to the first horizontal point to the voltage difference. The testing method is rapid and low in cost, the speed of oxygen storage change in the actual process can be quantitatively and visually displayed, and the defect of the existing testing technology in the aspect of evaluating the dynamic oxygen storage / release rate of the monolithic catalyst is overcome.

Description

Technical Field

[0001] The invention relates to a performance evaluation test method for a three-way catalyst for automobile exhaust purification, and in particular to a method and system for measuring the oxygen storage / release rate of a three-way catalyst for automobile exhaust on a catalytic performance evaluation device. Background Art

[0002] With the increasing global environmental awareness and increasingly stringent automobile emission regulations, the research and development of three-way catalysts (TWC) has become an important topic in the automobile industry. As a key technology for reducing the emission of hydrocarbons (HC), carbon monoxide (CO) and nitrogen oxides (NOx) in automobile exhaust, the performance evaluation of three-way catalysts is particularly critical. In the past, the evaluation of the processing capacity of catalysts under transition conditions mainly focused on the air-fuel ratio window and the total amount of oxygen storage / release, such as:

[0003] CN 101620035 A discloses a method for testing the oxygen storage capacity of an automobile exhaust catalyst, which provides a test method for realizing the oxygen storage capacity of an automobile exhaust catalyst on an engine bench, and can directly realize accurate measurement of the oxygen storage capacity of the catalyst on the engine bench. The test method is intuitive and fast. Its basic principle is to calculate the OSC value of the catalyst or catalytic converter by measuring the time difference of the signals of the front and rear narrow-band oxygen sensors after controlling the AFR value of the engine. Hardware conditions: front and rear narrow-band oxygen sensors, front and rear oxygen signal processors and engine control unit ECU controller, fast data acquisition card, etc. Software conditions: EXCLE or other processing software, calculation method: OSC=0.07712×Δλ×Δt×SV×Vr unit mg. Basic test method: 1) Control the engine working condition, the speed is 2900RPM (revolutions / minute), and the output power is 25kW; 2) The air-fuel ratio of the engine is switched from 0.96 to 1.06, and the switch is made every 20 seconds. The number of switching is no less than 10 times, and the middle periodic pattern area is taken for statistics; 3) the signal time difference in each waveform is counted, and the average time is calculated; 4) the oxygen storage capacity is calculated by an empirical formula.

[0004] CN112177737 A discloses a method, device, terminal and storage medium for testing the performance of a three-way catalytic converter. The method includes: adjusting the engine speed and throttle in real time to control the gas volume at the engine inlet end within a preset range; adjusting the excess air coefficient at the inlet end of the three-way catalytic converter to increase and decrease, and obtaining the post-oxygen voltage value in real time; calculating the oxygen storage time and oxygen release time of the catalyst in the three-way catalytic converter according to the change law of the excess air coefficient and the post-oxygen voltage value; and evaluating the performance of the three-way catalytic converter according to the oxygen storage time and oxygen release time. The present invention changes the parameters of the post-oxygen voltage value of the three-way catalytic converter by controlling the excess air coefficient, thereby measuring the oxygen storage time and oxygen release time of the catalyst and realizing the evaluation of the performance of the three-way catalytic converter.

[0005] In fact, many samples with large absolute values ​​of oxygen storage in transition conditions are not so effective in treating emissions. Studies have found that emission control in transition conditions is not only related to the total amount of oxygen stored / released by the catalyst, but also has a great correlation with the oxygen storage / release rate when the air velocity is large, which directly affects the catalyst's conversion efficiency of exhaust pollutants under different conditions (such as rapid acceleration, rapid deceleration, idling, etc.). Catalysts with high oxygen storage / release rates can respond more quickly to changes in exhaust gas composition, thereby maintaining a high conversion efficiency and reducing pollutant emissions. Therefore, the oxygen storage / release rate is one of the important indicators for measuring the catalytic conversion performance of catalyst exhaust gas, and the evaluation of the catalyst reaction rate is particularly important.

[0006] In summary, the current test methods for the oxygen storage / release rate of three-way catalysts are mainly focused on the measurement and analysis of the oxygen storage capacity of powdered catalysts. The tests for the oxygen storage / release rate of powdered catalysts mostly use oxygen isotope labeling, CO pulse and CO / O2 pulse methods. These methods can reflect the oxygen storage / release rate of the catalyst to a certain extent, but they have disadvantages such as long test cycle, high cost and complex operation. In addition, the oxygen storage / release rate of the powdered catalyst cannot accurately reflect the dynamic oxygen storage / release rate of the integral catalyst under actual working conditions, which is insufficient for evaluating the real-time performance of the catalyst. Rapid monitoring of the oxygen storage / release performance of the integral catalyst has become an urgent need, but the existing test methods are difficult to meet this requirement. In view of the limitations of the above tests, it is urgent to develop a test method that is fast, intuitive, low-cost and can reflect the dynamic oxygen storage / release rate of the three-way catalyst in real time. Summary of the invention

[0007] The purpose of the present invention is to provide a more intuitive and reliable oxygen storage / release rate test method, which can quantify the oxygen storage / release capacity of a monolithic catalyst under transient conditions. This method can calculate the rate at which the catalyst stores and releases oxygen in a short period of time, and screen out more efficient technical solutions when dealing with dynamic vehicle conditions.

[0008] Hardware conditions: ECU electronic control unit, engine, wide-band oxygen sensor LSU, front narrow-band oxygen sensor LSF1 and rear narrow-band oxygen sensor LSF2, dynamometer, exhaust pipe.

[0009] Specifically, the technical solution of the present invention is:

[0010] A method for measuring the oxygen storage / release rate of a three-way catalyst for automobile exhaust purification is implemented on a catalytic performance evaluation device to test the oxygen storage / release rate of the three-way catalyst for automobile exhaust purification. The oxygen storage rate is measured by controlling the engine air-fuel ratio to switch alternately from rich combustion to lean combustion, and the ratio of the time difference between the voltage of a rear narrow-band oxygen sensor and the voltage difference is used to measure the oxygen storage rate; and the oxygen release rate is measured by the ratio of the time difference between the voltage of a rear narrow-band oxygen sensor and the voltage difference is used to measure the oxygen release rate.

[0011] Furthermore, the oxygen voltage at the rear end of the catalyst is detected in real time by an oxygen sensor and data is collected. The response time of the unit rear oxygen voltage change is calculated using Excel data processing software to obtain the real-time oxygen storage / release rate. The formula is:

[0012]

[0013] Calculate the catalyst's oxygen storage / release rate Rate[O];

[0014] Wherein, U is the voltage value of the rear narrow-band oxygen sensor, in mV; ΔU is the voltage change difference of the rear narrow-band oxygen sensor during the oxygen storage / release cycle, in mV; Δt is the reaction time corresponding to ΔU, in s;

[0015] Based on the above theory, the data in the real-time rear narrow-band oxygen sensor voltage curve diagram is used for calculation, thereby intuitively reflecting the dynamic storage / release oxygen rate of the catalyst.

[0016] Further, ensure that the inlet and outlet of the catalyst are aligned with the interface on the bracket, and use a tool to connect the catalyst to the bracket.

[0017] Furthermore, during the air tightness inspection, the leakage amount or pressure decay is recorded and compared with a preset judgment threshold.

[0018] Furthermore, the operating parameters are set to simulate the real-time working state of the engine to ensure the accuracy of the test.

[0019] Furthermore, in the oxygen storage / release rate test, the data acquisition system is used to record in real time the changes in relevant parameters during the oxygen storage and release process of the catalyst.

[0020] Furthermore, under the specified parameter conditions of the oxygen storage / release rate test, the excess air coefficient at the inlet of the three-way catalytic converter is adjusted for cyclic switching. The time interval for each switching is the same, and the interval time should ensure that the test conditions are stable for at least 20 seconds until the voltage of the rear narrow-band oxygen sensor is stable, and the number of switching times is not less than 10 times.

[0021] Furthermore, the value of Rate[O] is calculated by Excel data processing software, and the specific steps are as follows:

[0022] (1) Selecting a periodic oxygen storage area and oxygen release area in the middle;

[0023] (2) Select the starting change point and the point where the narrow-band oxygen sensor LSF2 reaches the first level, take the voltage difference between the two points as ΔU, and take the response time difference between the two points as Δt;

[0024] (3) Use Excel data processing software to calculate Δt / ΔU.

[0025] A system for measuring the oxygen storage / release rate of a three-way catalyst for automobile exhaust purification comprises a wide-band oxygen sensor LSU, a front narrow-band oxygen sensor LSF1, a temperature sensor, a three-way catalyst TWC and a rear narrow-band oxygen sensor LSF2 which are sequentially arranged along the flow direction of the engine exhaust gas, and also comprises an electronic control unit ECU and a dynamometer. The wide-band oxygen sensor LSU, the front narrow-band oxygen sensor LSF1 and the rear narrow-band oxygen sensor LSF2 convert the detected oxygen content into an electrical signal through an electrochemical redox reaction to obtain data related to changes in the oxygen storage / release of the catalyst; the dynamometer can change the load and speed of the power system by simulating the load condition of the automobile on the road, thereby simulating various working conditions in the actual operation of the engine; the electronic control unit ECU receives the signals of each sensor and simulates the operation of the engine under the actual working conditions by adjusting parameters; the method for measuring the oxygen storage / release rate of the three-way catalyst for automobile exhaust purification according to the present invention is used to obtain the real-time oxygen storage / release rate Rate[O].

[0026] The test principle of the oxygen storage / release rate involved in the present invention includes:

[0027] By controlling the switching of the engine air-fuel ratio from rich to lean, the oxygen storage and release of the catalyst cause a delayed transition in the voltage of the rear narrow-band oxygen sensor when the oxygen concentration behind the catalyst reaches equilibrium. The oxygen storage rate is determined by the ratio of the time difference from the point where the rear oxygen voltage starts to change from a high point to the first horizontal point to the voltage difference; the oxygen release rate is determined by the ratio of the time difference from the point where the rear oxygen voltage starts to change from a low point to the first horizontal point to the voltage difference.

[0028] The beneficial effects of the present invention include:

[0029] (1) The present invention provides a method for evaluating the reaction rate of the actual application scenario of the catalyst, thereby improving the matching degree between the catalyst and the vehicle emissions;

[0030] (2) The calculation of oxygen storage capacity and storage / release rate of a catalyst, including pretreatment, only takes 50 minutes, and the test efficiency is high;

[0031] (3) The present invention utilizes a test bench to provide exhaust gas, thereby making the catalyst storage / release rate performance test and vehicle test more consistent. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 : System stand layout diagram of the present invention.

[0033] Figure 2 : Schematic diagram of the calculation process of the present invention.

[0034] Figure 3 : A diagram of the calculation method of the oxygen storage / release rate of the present invention, wherein: a is a post-oxygen signal diagram, and b is a schematic diagram of the oxygen storage rate calculation.

[0035] Figure 4 : Oxygen storage / release rate test data curve within a certain period.

[0036] Figure 5 : Dynamic oxygen storage / release rate test data diagram of the catalyst, where: a is dynamic oxygen storage, b is dynamic oxygen release. DETAILED DESCRIPTION

[0037] In order to make the technical means and creative features implemented by the present invention clearer and easier to understand, the present invention is further explained below in conjunction with an oxygen storage / release rate test example and accompanying drawings.

[0038] like Figure 1 As shown, the catalyst storage / release oxygen rate performance evaluation device includes: an ECU electronic control unit, a wide-range oxygen sensor LSU, a front narrow-range oxygen sensor LSF1 and a rear narrow-range oxygen sensor LSF2, a dynamometer, etc. Among them:

[0039] 1) The wide-band oxygen sensor LSU, the front narrow-band oxygen sensor LSF1, and the rear narrow-band oxygen sensor LSF2 convert the detected oxygen content into electrical signals through electrochemical redox reactions to obtain data on changes in catalyst oxygen storage / release;

[0040] 2) The dynamometer can change the load and speed of the power system by simulating the load conditions of the car on the road, thereby simulating various working conditions in actual operation;

[0041] 3) The ECU electronic control unit receives sensor signals from various systems and simulates the operation of the engine under actual working conditions by adjusting parameters.

[0042] The catalyst oxygen storage / release rate test was carried out by switching alternately under lean / rich conditions.

[0043] like Figure 2 As shown, the specific steps of the test method for the oxygen storage / release rate of the three-way catalyst include:

[0044] (1) Installation of catalyst samples

[0045] Check that the catalyst sample has no damage on its appearance, fix the catalyst mounting bracket on the vehicle test bench, and make sure that the front end of the carrier is 100±10mm away from the inlet temperature sensor collection point, and ensure that the bracket is positioned accurately and firmly. Use a torque wrench to tighten the bracket bolts, avoiding over-tightening or over-loosening. Place the catalyst on the mounting bracket, ensure that the catalyst inlet and outlet are aligned with the interface on the bracket, and use tools to connect the catalyst to the bracket.

[0046] (2) Air tightness inspection of the device

[0047] Prepare air tightness testing equipment and ensure that all equipment is in good condition. Set parameters such as test pressure, voltage stabilization time and judgment threshold according to the characteristics of the catalyst and vehicle requirements. Connect the air inlet of the air tightness testing equipment to the air inlet of the catalyst, and plug the air outlet with a rubber plug. Turn on the gas source, fill the catalyst and its connected pipe system with gas, keep the gas pressure in the system stable for a period of time, and use a pressure sensor to detect and record the changes in the gas pressure in the system.

[0048] After the set pressure stabilization time is over, the leakage or pressure decay is recorded and compared with the preset judgment threshold. If the decay value or leakage exceeds the threshold, it is judged that the catalyst and its connection system have leakage, and the connection needs to be rechecked and tightened; if the decay value or leakage is within the allowable range, it is judged that the catalyst and its connection system are airtight.

[0049] (3) Operation parameter settings

[0050] First, start the hot engine and adjust the engine speed and throttle in real time to control the gas volume at the engine inlet end at 40Kg / h. In addition, monitor and adjust the catalyst inlet temperature to 500℃.

[0051] (4) Test method for oxygen storage / release rate

[0052] Under the specified parameter conditions of the oxygen storage / release rate test, adjust the excess air coefficient at the inlet of the three-way catalytic converter and switch it cyclically. The time interval between each switch is the same, and the interval time should ensure that the test conditions stabilize for at least 20 seconds until the voltage of the rear narrow-band oxygen sensor stabilizes. The number of switches should be no less than 10 times.

[0053] During the switching process, the data acquisition system is used to record the changes of all relevant parameters. From the recorded data, the periodic oxygen storage and release sections in the middle are identified and selected as the analysis objects.

[0054] (5) Calculation of oxygen storage / release rate

[0055] The calculation formula of the oxygen storage / release rate derived according to the oxygen storage / release rate test principle involved in the present invention is as follows:

[0056]

[0057] Where, Rate[O] is in s·mV -1 .

[0058] The value of Rate[O] is calculated using Excel data processing software. The specific steps are as follows:

[0059] (1) Selecting a periodic oxygen storage area or oxygen release area in the middle;

[0060] (2) Record the starting change point and the first level point of the rear narrow-band oxygen sensor LSF2, and record the voltage difference between the two points as ΔU and the response time difference as Δt;

[0061] (3) Use Excel software to calculate Δt / ΔU, which is the Rate[O] value.

[0062] Example 1

[0063] Select the catalyst sample, check that the catalyst sample has no damage on the outside, and then fix the catalyst mounting bracket on the vehicle test bench.

[0064] In this embodiment 1, the oxygen storage rate and oxygen release rate of the three-way catalyst are obtained by the following formula, wherein the formula is

[0065]

[0066] The calculation result of the oxygen storage / release rate of the catalyst is in s·mV -1 ;

[0067] Wherein, Rate[O] can be calculated by Excel data processing software. The specific steps are as follows: select the middle periodic oxygen storage area or oxygen release area, record the point where the rear oxygen signal LSF2 starts to change and the point where it is horizontal for the first time, take the voltage value between the two points, record it as ΔU, and the response time difference between the two points is recorded as Δt; use Excel software to calculate the unit voltage change response time Δt / ΔU, which is the Rate[O] value.

[0068] In Example 1, the catalyst sample was tested for oxygen storage / release rate, the catalyst inlet temperature was 500°C, and the gas volume at the inlet was 40Kg / h. The engine was switched to open-loop mode, and the LSU air-fuel ratio was controlled to switch from 0.95 to 1.05, once every 30 seconds, and the number of switching times was 10;

[0069] like Figure 3 As shown, the middle periodic oxygen storage pattern area is selected for data processing (such as Figure 5 shown), then:

[0070] ΔU is: 729.77mV, 716.8mV, 734.85mV, 721.68mV, 724.12mV, 717.78mV, 717.76mV, 724.68mV, 728.32mV, 730.9mV;

[0071] Δt is: 10.94s, 10.76s, 9.66s, 8.21s, 9.02s, 9.19s, 9.13s, 8.72s, 8.72s, 8.62s;

[0072] Calculate the oxygen storage rate: 0.015s·mV -1 , 0.015s·mV -1 , 0.013s·mV -1 、0.011s·mV -1 , 0.012s·mV -1 , 0.013s·mV -1 , 0.013s·mV -1 , 0.012s·mV -1 , 0.012s·mV -1 , 0.012s·mV -1 , take the average value as 0.013s·mV -1 , then the oxygen storage rate of the catalyst is 0.013s·mV -1 .

[0073] Take the middle periodic oxygen release pattern area for data processing (such as Figure 5 shown), then:

[0074] ΔU is: 733.45mV, 728.07mV, 719.3mV, 725.52mV, 726.94mV, 724.95mV, 731.47mV, 732.6mV, 721.57mV, 725.81mV;

[0075] Δt is: 12.86s, 13.23s, 12.5s, 13.51s, 12.88s, 12.92s, 12.93s, 12.83s, 12.62s, 13.04s;

[0076] Calculated oxygen release rate: 0.018s·mV -1 , 0.018s·mV -1 , 0.017s·mV -1 , 0.019s·mV -1 , 0.018s·mV -1 , 0.018s·mV -1 , 0.018s·mV -1 , 0.018s·mV -1 , 0.017s·mV -1 , 0.018s·mV -1 , take the average value as 0.018s·mV -1 , then the oxygen evolution rate of the catalyst is 0.018s·mV -1 .

[0077] Example 2

[0078] In this embodiment, the catalyst sample is tested for oxygen storage / release rate, the catalyst inlet temperature is 500°C, and the gas volume at the inlet is 40Kg / h. The engine is switched to open-loop mode, and the LSU air-fuel ratio is controlled to switch from 0.95 to 1.05, once every 30 seconds, and the number of switching times is 10.

[0079] Take the middle periodic oxygen storage pattern area for data processing (such as Figure 5 shown), then:

[0080] ΔU is: 674.80mV, 678.71mV, 675.29mV, 676.27mV, 673.83mV, 675.29mV, 681.15mV, 682.13mV, 683.59mV, 683.59mV;

[0081] Δt is: 3.82s, 3.21s, 2.74s, 3.28s, 3.83s, 3.64s, 3.73s, 3.09s, 2.91s, 3.10s;

[0082] Calculated oxygen storage rate: 0.0057s·mV -1 , 0.0047s·mV -1 、0.0041s·mV -1 , 0.0049s·mV -1 、0.0057s·mV -1, 0.0054s·mV -1 、0.0055s·mV -1 、0.0045s·mV -1 , 0.0043s·mV -1 、0.0045s·mV -1 , and the average value is 0.0049s·mV -1 , then the oxygen storage rate of the catalyst is 0.0049s·mV -1 .

[0083] Take the middle periodic oxygen release pattern area for data processing (such as Figure 5 shown), then:

[0084] ΔU is: 605.47mV, 590.82mV, 615.23mV, 614.26mV, 599.12mV, 599.12mV, 583.50mV, 590.82mV, 598.14mV, 607.91mV;

[0085] Δt is: 3.93s, 3.47s, 3.83s, 3.37s, 3.56s, 4.46s, 4.18s, 4.56s, 4.29s, 4.01s;

[0086] Calculated oxygen release rate: 0.0065s·mV -1 , 0.0059s·mV -1 , 0.0062s·mV -1 、0.0055s·mV -1 , 0.0059s·mV -1 、0.0074s·mV -1 、0.0072s·mV -1 , 0.0077s·mV -1 、0.0072s·mV -1 , 0.0066s·mV - 1 , take the average value as 0.0066s·mV -1 , then the oxygen release rate of the catalyst is 0.0066s·mV -1 .

[0087] Example 3

[0088] In this embodiment, the catalyst sample is tested for oxygen storage / release rate, the catalyst inlet temperature is 500°C, and the gas volume at the inlet is 40Kg / h. The engine is switched to open-loop mode, and the LSU air-fuel ratio is controlled to switch from 0.95 to 1.05, once every 30 seconds, and the number of switching times is 10.

[0089] Take the middle periodic oxygen storage pattern area for data processing (such as Figure 5 shown), then:

[0090] ΔU is: 678.03mV, 675.14mV, 679.71mV, 680.67mV, 679.95mV, 679.47mV, 680.67mV, 683.56mV, 677.55mV, 680.67mV;

[0091] Δt is: 1.09s, 1.00s, 1.22s, 1.37s, 1.09s, 1.16s, 0.82s, 1.03s, 1.71s, 1.10s;

[0092] Calculated oxygen storage rate: 0.0016s·mV -1 , 0.0015s·mV -1 、0.0018s·mV -1 , 0.0020s·mV -1 , 0.0016s·mV -1 、0.0017s·mV -1 , 0.0012s·mV -1 , 0.0015s·mV -1 , 0.0025s·mV -1 , 0.0016s·mV -1 , take the average value as 0.0017s·mV -1 , then the oxygen storage rate of the catalyst is 0.0017s·mV -1 .

[0093] Take the middle periodic oxygen release pattern area for data processing (such as Figure 5 shown), then:

[0094] ΔU is: 661.19mV, 654.70mV, 659.03mV, 659.27mV, 660.47mV, 658.06mV, 658.30mV, 653.26mV, 662.88mV, 663.12mV;

[0095] Δt is: 0.82s, 1.01s, 0.72s, 1.19s, 1.09s, 1.18s, 1.01s, 0.82s, 0.92s, 1.56s;

[0096] Calculated oxygen release rate: 0.0012s·mV -1 , 0.0015s·mV -1 , 0.0011s·mV -1 、0.0018s·mV -1、0.0017s·mV -1 、0.0018s·mV -1 , 0.0015s·mV -1 、0.0013s·mV -1 , 0.0014s·mV -1 , 0.0024s·mV -1 , take the average value as 0.0016s·mV -1 , then the catalyst oxygen release rate is 0.0016s·mV -1 .

Claims

1. A method for measuring the oxygen storage / release rate of a three-way catalyst for automobile exhaust purification, characterized in that: The oxygen storage / release rate test of the automobile exhaust purification three-way catalyst is realized on the catalytic performance evaluation device. By controlling the engine air-fuel ratio to switch alternately from rich to lean, the oxygen storage rate is determined by the ratio of the time difference between the voltage of the rear narrow-band oxygen sensor and the voltage difference from the high starting point to the first horizontal point; the oxygen release rate is determined by the ratio of the time difference between the voltage of the rear narrow-band oxygen sensor and the voltage difference from the low starting point to the first horizontal point; the oxygen storage / release rate Rate[O] is calculated by the following formula: Where ΔU is the voltage change difference of the rear narrow-band oxygen sensor during the oxygen storage / release cycle, and Δt is the response time difference.

2. The method for determining the oxygen storage / release rate of a three-way catalyst for automobile exhaust purification according to claim 1, characterized in that: The specific steps include the following: Step 1, fix the catalyst mounting bracket on the automobile test bench so that the front end surface of the carrier is at an appropriate distance from the inlet temperature collection point; Step 2: Air tightness check and parameter setting According to the characteristics of the catalyst and vehicle requirements, set the detection pressure, voltage stabilization time and judgment threshold, check the air tightness and ensure that the catalyst connection is in good air tightness; Start the hot engine, adjust the engine speed and throttle in real time to control the gas volume at the engine inlet, monitor and adjust the catalyst inlet temperature; Step 3: Oxygen storage / release rate test Under the specified parameter conditions of the oxygen storage / release rate test, adjust the excess air coefficient at the inlet of the three-way catalytic converter and switch it several times; During the switching process, the data acquisition system is used to record the changes of all relevant parameters, and from the recorded data, the periodic oxygen storage section and oxygen release section in the middle are identified and selected as the analysis objects; Step 4, calculate the oxygen storage / release rate Rate[O].

3. The method for determining the oxygen storage / release rate of a three-way catalyst for automobile exhaust purification according to claim 2, characterized in that: In step 1: The front end surface of the carrier is 90 to 110 mm away from the inlet temperature collection point.

4. The method for determining the oxygen storage / release rate of a three-way catalyst for automobile exhaust purification according to claim 2, characterized in that: In step 2: The gas volume at the engine inlet was controlled at 40 kg / h, and the catalyst inlet temperature was monitored and adjusted to 500°C.

5. The method for determining the oxygen storage / release rate of a three-way catalyst for automobile exhaust purification according to claim 2, characterized in that: In step 3: The switching time interval is the same each time, and the interval time should ensure that the test conditions are stable for at least 20 seconds until the voltage of the narrow-band oxygen sensor stabilizes.

6. The method for determining the oxygen storage / release rate of a three-way catalyst for automobile exhaust purification according to claim 2, characterized in that: In step 3: The number of switching times is not less than 10 times.

7. The method for determining the oxygen storage / release rate of a three-way catalyst for automobile exhaust purification according to claim 2, characterized in that: Step 3 also includes: The engine switches to open-loop mode and controls the LSU air-fuel ratio to switch from 0.95 to 1.

05.

8. A method for determining the oxygen storage / release rate of a three-way catalyst for automobile exhaust purification according to any one of claims 1 to 7, characterized in that: The value of the oxygen storage / release rate Rate[O] is calculated by Excel data processing software, and the specific steps are as follows: (1) Selecting a periodic oxygen storage area and oxygen release area in the middle; (2) Select the starting point of the voltage signal change of the narrow-band oxygen sensor and the point where it reaches the first level, take the voltage difference between the two points as ΔU, and take the response time difference between the two points as Δt; (3) Use Excel data processing software to calculate Δt / ΔU.

9. A system for measuring the oxygen storage / release rate of a three-way catalyst for automobile exhaust purification, characterized in that: The system includes a wide-range oxygen sensor LSU, a front narrow-range oxygen sensor LSF1, a temperature sensor, a three-way catalyst TWC and a rear narrow-range oxygen sensor LSF2 arranged in sequence along the flow direction of the engine exhaust gas, and also includes an electronic control unit ECU and a dynamometer; The wide-band oxygen sensor LSU, the front narrow-band oxygen sensor LSF1 and the rear narrow-band oxygen sensor LSF2 convert the detected oxygen content into an electrical signal through an electrochemical redox reaction to obtain data on changes in catalyst oxygen storage / release; It also includes a real-time oxygen storage / release rate Rate[O] using a method for determining the oxygen storage / release rate of a three-way catalyst for automobile exhaust purification as described in any one of claims 1 to 9.

10. The system for measuring the oxygen storage / release rate of a three-way catalyst for automobile exhaust purification according to claim 9, characterized in that: The dynamometer simulates the load condition of the car on the road and simulates various working conditions of the engine in actual operation by changing the load and speed of the power system; The electronic control unit ECU receives signals from various sensors and simulates the operation of the engine under actual working conditions by adjusting parameters.

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