shunt temperature control device for automotive catalyst oxygen storage capacity evaluation bench system

Abstract

This utility model discloses a flow-diversion and temperature control device for an automotive catalyst oxygen storage capacity evaluation bench system, belonging to the field of automotive catalyst oxygen storage capacity evaluation bench systems. The device includes an execution unit and a control unit. The execution unit is connected to the engine exhaust manifold outlet and includes a flow-diversion mechanism and a temperature control mechanism. When the engine is running, the flow-diversion mechanism diverts the engine exhaust gas source to control the exhaust gas flow rate entering the catalyst body. The temperature control mechanism is located at the inlet of the flow-diversion mechanism and is used to control the temperature of the engine exhaust gas source. The control unit controls the execution unit. This device solves the problem that conventional engine bench systems with single-pipe structures cannot adjust the exhaust flow rate during automotive catalyst oxygen storage capacity evaluation testing, and the problem of catalyst inlet temperature fluctuations caused by long stabilization times before and after rich / lean switching of the excess air coefficient, ensuring the accuracy of oxygen storage capacity testing.

Description

Technical Field

[0001] This utility model relates to an evaluation test bench system for the oxygen storage capacity of automotive catalysts, specifically to a diversion temperature control device for such a test bench system. Background Technology

[0002] Currently, light-duty gasoline vehicles typically use after-treatment catalyst systems, such as three-way catalytic converters (TWC) and catalytic particulate filters (CGPF), to control exhaust emissions to meet standards. The oxygen storage capacity of these catalysts is usually tested and evaluated based on engine bench systems.

[0003] Oxygen storage capacity refers to the ability of a catalyst to store and release oxygen under conditions of rich / lean air-fuel ratio switching in an automotive engine. It is one of the important indicators for the development and design of catalysts for automotive exhaust purification. When the engine is close to the stoichiometric air-fuel ratio, the catalyst is most efficient at simultaneously purifying the main pollutants in automotive exhaust, namely CO, HC, and NOx. Gasoline engines mostly operate under conditions deviating from the stoichiometric air-fuel ratio. For example, the Worldwide Harmonized Light Vehicles Test Cycle (WLTC) involves frequent rapid acceleration and deceleration, which can cause the catalyst's operating window to be unable to fully adapt to the rapid rich / lean air-fuel ratio switching. The oxygen storage capacity of a catalyst is mainly determined by intrinsic factors such as the carrier coating material and the active metal supported on it. Under the aforementioned conditions, the main external environmental factors affecting oxygen storage performance are the air-fuel ratio modulation window, engine exhaust gas flow rate, catalyst inlet temperature, and catalyst degradation level.

[0004] The oxygen storage capacity of the catalyst is tested by adjusting the engine control to achieve a rich excess air coefficient (λ), i.e., λ = 0.90 (or 0.95). After the test conditions stabilize for at least 20 seconds until the oxygen sensor voltage signal stabilizes, the engine control is adjusted to shift λ to a lean state, i.e., λ = 1.10 (or 1.05), at which point a sudden change occurs, and the changes in the voltage signals of the front and rear oxygen sensors are collected. Using the collected changes in the voltage signals of the front and rear oxygen sensors, as well as the intake air flow rate and the change in λ during the sudden change, the oxygen storage capacity of the TWC is calculated. This process is repeated at least 5 times, and the arithmetic mean is calculated.

[0005] The current industry standard specifies that bench oxygen storage capacity testing is conducted by adjusting engine operating conditions, such as controlling engine speed and throttle, to regulate inlet temperature and intake airflow. However, this method has the following drawbacks:

[0006] First, the engine's exhaust flow cannot be adjusted. This is because the exhaust pipes on the test benches used by different testing laboratories for oxygen storage capacity testing generally adopt a single-inlet, single-outlet structure. Each laboratory selects different engine models and displacements. Under the same engine operating conditions, the same intake flow will result in different fuel consumption, leading to inconsistent engine exhaust flow. This will affect the chemical reaction space velocity of the catalyst, ultimately resulting in inconsistent oxygen storage capacity in the test, making it impossible to achieve complete benchmarking and qualification certification.

[0007] Secondly, the inlet temperature fluctuates significantly during the oxygen storage capacity test. During the engine bench oxygen storage capacity test, the duration of stability in the rich and lean regions before and after the rich / lean transition affects the inlet temperature. A longer stability time in the rich region leads to incomplete combustion and a lower inlet temperature; conversely, a longer stability time in the lean region results in a higher inlet temperature under lean-burn conditions. The allowable deviation of the inlet temperature is within ±10℃ of the selected inlet temperature. Shorter stability times before and after the rich / lean transition have less impact on the inlet temperature but may result in insufficient oxygen capture from the catalyst with a large oxygen storage capacity. Longer stability times before and after the rich / lean transition cause the inlet temperature to deviate from the selected inlet temperature deviation value. Utility Model Content

[0008] The purpose of this invention is to provide a flow control and temperature control device for an automotive catalyst oxygen storage capacity evaluation bench system, which aims to solve the problems of unavoidable exhaust flow adjustment and catalyst inlet temperature fluctuation under existing technical conditions.

[0009] The objective of this utility model is achieved through the following technical solution:

[0010] A flow-diverting temperature control device for an automotive catalyst oxygen storage capacity evaluation bench system includes an execution unit and a control unit; the execution unit is connected to the engine exhaust manifold outlet; the execution unit includes a flow-diverting mechanism and a temperature control mechanism.

[0011] While maintaining engine operating conditions, the diversion mechanism is used to divert engine exhaust gas to adjust the exhaust flow rate entering the catalyst. The control unit controls the operation of the execution unit. By keeping the engine operating conditions constant, the diversion mechanism in the execution unit diverts the engine exhaust gas to adjust the exhaust flow rate entering the catalyst, ensuring the exhaust flow rate control accuracy is less than 0.5 g / s. This allows for precise testing of the catalyst's oxygen storage performance under different exhaust flow rates. The control unit can precisely control the diversion mechanism in the execution unit to divert the exhaust gas without adjusting the engine operating conditions to regulate the exhaust flow rate entering the catalyst, thus maintaining the oxygen content in the exhaust gas and ensuring the accuracy of the oxygen storage test. Ultimately, this enables precise benchmarking of oxygen storage against third-party testing institutions.

[0012] Furthermore, the flow splitting mechanism includes a test pipeline and a flow splitting pipeline arranged in parallel. The test pipeline is horizontally connected to the engine exhaust manifold outlet, and the flow splitting pipeline is connected to the test pipeline at a 45-degree angle, thereby ensuring the uniformity of the gas flow field in the test pipeline. The exhaust gas source on the exhaust pipeline is split by the parallel test pipeline and the flow splitting pipeline. When the required exhaust flow rate is small, more gas flows into the flow splitting pipeline, and when the required exhaust flow rate is large, more gas flows into the test pipeline. By controlling the gas flow rate on the two pipelines, the exhaust flow rate entering the catalyst is controlled, making the exhaust flow rate control more precise and stable, and better ensuring the stability of the oxygen storage test.

[0013] Furthermore, a first throttle valve is installed at the rear end of the diversion pipeline, and a second throttle valve is installed at the rear end of the test pipeline. The first throttle valve and the second throttle valve are respectively installed on the diversion pipeline and the test pipeline to better control the gas flow rate of the catalyst entering the test pipeline. In order to prevent the test pipeline and the diversion pipeline from being completely closed, which would cause the engine to stall due to poor exhaust, the throttle valves of the test pipeline and the diversion pipeline are both set to be in a state that cannot be completely closed, allowing at least 10 kg / h of airflow to pass through.

[0014] While maintaining engine operating conditions, the temperature control mechanism is used to reduce the exhaust temperature at the catalyst inlet, thereby controlling the temperature fluctuation of the exhaust gas source at the catalyst inlet to be less than ±10℃. The temperature control mechanism is connected to the inlet of the flow divider. When the catalyst inlet temperature deviates from the target temperature during the stabilization process after the air-fuel ratio rich-lean switching, it is not necessary to adjust the engine operating conditions to regulate the catalyst inlet temperature. With the engine operating conditions remaining constant, the temperature control mechanism precisely controls the temperature of the engine's exhaust gas source, minimizing the temperature deviation of the catalyst inlet temperature caused by excessively long stabilization time after the air-fuel ratio switching, and ensuring the accuracy of the oxygen storage capacity test.

[0015] Furthermore, the temperature control mechanism includes an air supply device and heat dissipation fins; the air supply device includes an electric air compressor, an air storage tank, and an air supply valve for the air storage tank; the electric air compressor is used to supply compressed air to the heat dissipation fins, and the air storage tank is used to store the compressed air and stabilize the output pressure. When the pressure reaches the set value, the exhaust valve opens, and the compressed air enters the air storage tank; the heat dissipation fins are located at the front end of the test pipeline of the flow splitting mechanism and are used to control the temperature of the airflow in the test pipeline; the temperature control mechanism is located at the front end of the test pipeline of the flow splitting mechanism. When the catalyst inlet temperature is higher than the target temperature, the control unit opens the air supply valve of the air storage tank through the program instruction of the control system, and delivers the compressed air to the heat dissipation fins to cool the airflow in the test pipeline; when the catalyst inlet temperature drops to the target temperature, the execution unit closes the air supply valve of the air storage tank through the program instruction of the control system, and stops blowing compressed air onto the heat dissipation fins.

[0016] Furthermore, the execution unit also includes an intake flow meter, an orifice plate flow meter, and a temperature sensor: the intake flow meter is installed at the inlet of the engine intake manifold; the orifice plate flow meter is installed at a certain distance from the aftertreatment outlet; the temperature sensor is installed at the inlet of the aftertreatment; the intake flow meter is a thermal gas flow meter, installed at the inlet of the engine intake manifold, used to detect the intake volume of the engine throttle valve to accurately reflect the engine's intake flow rate; the orifice plate flow meter detects the gas flow rate entering the catalyst; the temperature sensor can be installed according to the required model, structure, and suitable connection method, and is installed at the inlet of the aftertreatment to detect the inlet temperature of the catalyst to accurately reflect the inlet temperature of the catalyst.

[0017] Furthermore, the control unit is electrically connected to the inlet flow meter, orifice plate flow meter, temperature sensor, throttle valve, and air supply valve of the air tank. The control unit uses commercially available products, such as a PLC, and is configured to acquire data from the inlet flow meter, orifice plate flow meter, and temperature sensor. Based on the acquired flow rate values ​​and preset control thresholds, it controls the opening or closing of the throttle valve and the air supply valve of the air tank based on the acquired temperature and preset control thresholds.

[0018] This utility model has the following advantages:

[0019] 1. The flow splitting mechanism in the execution unit of this utility model is connected to the exhaust manifold outlet of the engine, so that the engine operating conditions remain unchanged. The flow splitting mechanism in the execution unit splits the exhaust flow of the engine, so that the exhaust flow entering the catalyst can be adjusted and the exhaust flow fluctuation of the catalyst is less than 0.5g / s; thereby, the oxygen storage performance of the catalyst at different exhaust flow points can be accurately tested.

[0020] 2. The control unit of this utility model can control the execution unit to divert the exhaust gas source of the engine, without having to adjust the gas flow rate into the catalyst by adjusting the engine operating conditions. This effectively solves the problem that the single-pipe structure cannot adjust the exhaust flow rate in the conventional testing methods of the industry, and ensures the accuracy of the oxygen storage capacity test.

[0021] 3. The temperature control mechanism in the execution unit of this utility model is connected to the inlet of the test pipeline of the flow divider, so that the engine operating condition remains unchanged. The temperature control mechanism in the execution unit is used to control the temperature of the test pipeline of the flow divider, so as to control the inlet temperature fluctuation of the catalyst in the test pipeline to be less than ±10℃; thereby, the oxygen storage performance of the catalyst at different catalyst inlet temperature points can be accurately tested.

[0022] 4. The control unit of this utility model can control the execution unit to control the temperature of the engine exhaust gas source, without having to adjust the engine operating conditions to adjust the inlet temperature of the catalyst; it solves the problem of catalyst inlet temperature fluctuation caused by the long stabilization time before and after the air-fuel ratio rich / lean switching, and ensures the accuracy of oxygen storage and release test.

[0023] 5. The operation of the execution unit of this utility model is achieved independently of the engine operating conditions. Therefore, the oxygen content in the engine exhaust gas source will not change due to the engine operating conditions, thereby ensuring that the oxygen storage capacity test can control a single variable and ensure the accuracy of the test results.

[0024] 6. The oxygen storage performance of the catalyst is very sensitive to changes in engine exhaust flow rate; a fluctuation of 1.5 g / s in exhaust flow rate is sufficient to cause a fluctuation of more than 6% in oxygen storage capacity. The flow splitting mechanism provided by this invention is located between the engine exhaust manifold and the aftertreatment system. When there is a difference between the exhaust flow rate entering the catalyst and the engine exhaust flow rate, the flow splitting system of this invention automatically adjusts the exhaust flow rate entering the catalyst, avoiding fluctuations in the oxygen storage capacity of the catalyst caused by exhaust flow rate fluctuations in low-temperature sensitive areas.

[0025] 7. The oxygen storage performance of a catalyst is highly sensitive to changes in the engine catalyst inlet temperature; a temperature fluctuation of ±15℃ is sufficient to cause a change in oxygen storage capacity exceeding 13%. The temperature control mechanism provided by this invention is located between the exhaust manifold and the splitter mechanism of the automotive engine. When there is a difference between the actual catalyst temperature and the target temperature, the temperature control mechanism of this invention automatically adjusts the catalyst inlet temperature to avoid fluctuations in the catalyst's oxygen storage capacity caused by the catalyst inlet temperature deviation. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the structure of this utility model.

[0027] Figure 2 This is a logic framework diagram of the control unit of this utility model.

[0028] Figure 3 The results show the impact of exhaust flow fluctuations on the catalyst's oxygen storage capacity.

[0029] The attached figures are labeled as follows:

[0030] 1. Control unit; 3. Flow splitting mechanism; 4. Temperature control mechanism; 5. Flow splitting pipeline; 6. Test pipeline; 7. Heat dissipation fins; 8. Electric air compressor; 9. Air tank; 9-1. Air supply valve of air tank; 10. Temperature sensor; 11. First throttle valve; 12. Second throttle valve; 13. First orifice plate flow meter; 14. Second orifice plate flow meter; 15. Inlet flow meter; 16. Engine; 17. Aftertreatment catalyst. Detailed Implementation

[0031] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer and easier to understand, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings.

[0032] Example 1

[0033] like Figure 1 As shown, a flow-diverting temperature control device for an automotive catalyst oxygen storage capacity evaluation bench system includes an execution unit and a control unit 1; the execution unit is connected to the engine exhaust manifold outlet; the execution unit includes a flow-diverting mechanism 3 and a temperature control mechanism 4; the control unit 1 is used to control the operation of the execution unit.

[0034] A diversion pipe 5 is installed at the end of the test pipe 6 connecting the engine 16 and the aftertreatment catalyst 17, near the engine 16. The test pipe 6 is horizontally connected to the engine exhaust manifold outlet, and the connection between the diversion pipe 5 and the test pipe 6 forms a 45-degree angle to ensure the uniformity of the gas flow field in the test pipe. By connecting the test pipe 6 and the diversion pipe 5 in parallel, the exhaust gas source in the exhaust pipe is diverted. When the required exhaust flow rate is small, more gas flows into the diversion pipe 5; when the required exhaust flow rate is large, more gas flows into the test pipe 6. By controlling the gas flow rate in the two pipes, the exhaust flow rate entering the catalyst is controlled, making the exhaust flow rate control more precise and stable, and better ensuring the stability of the oxygen storage capacity test.

[0035] A first throttle valve 11 is installed at the rear end of the diversion pipe 5, and a second throttle valve 12 is installed after the aftertreatment catalyst 17 at the rear end of the test pipe 6. The gas flow rate entering the aftertreatment catalyst 17 in the test pipe 6 is controlled by the first throttle valve 11 and the second throttle valve 12. To prevent the test pipe 6 and the diversion pipe 5 from being completely shut off, which would cause the engine to stall due to poor exhaust, the throttle valves of the test pipe 6 and the diversion pipe 5 are both set to be in a state where they cannot be completely closed, allowing at least 10 kg / h of airflow to pass through.

[0036] The temperature control mechanism 4 includes an air supply device and heat dissipation fins 7. The air supply device consists of an electric air compressor 8 connected to an air storage tank 9. The air storage tank 9 stores compressed air and supplies compressed air to the heat dissipation fins 7 through the air supply valve 9-1. The heat dissipation fins 7 cover the front end of the test pipeline 6, located at the post-treatment catalyst 17. The temperature of the airflow in the test pipeline 6 is controlled by blowing compressed air onto the heat dissipation fins 7. A temperature sensor 10 is installed in the test pipeline 6 between the heat dissipation fins 7 and the post-treatment catalyst 17 to measure the air temperature in the test pipeline 6 at the inlet of the post-treatment catalyst 17. When the temperature is higher than the target temperature, the control unit opens the air supply valve 9-1 of the air storage tank to deliver compressed air to the heat dissipation fins 7 and cool the airflow in the test pipeline 6. When the inlet temperature of the post-treatment catalyst 17 drops to the target temperature, the air supply valve 9-1 of the air storage tank is closed to stop blowing compressed air onto the heat dissipation fins 7. The temperature sensor can be installed according to the required model structure and appropriate connection method. The temperature sensor is set at the inlet of the post-processing to detect the inlet temperature of the catalyst, so as to accurately reflect the inlet temperature of the catalyst.

[0037] The execution unit further includes an intake flow meter 15, a first orifice plate flow meter 13, and a second orifice plate flow meter 14: the intake flow meter 15 is installed at the inlet of the engine intake manifold; the first orifice plate flow meter 13 and the second orifice plate flow meter 14 are respectively installed after the first throttle valve 11 and the second throttle valve 12; the intake flow meter 15 is a thermal gas flow meter used to detect the intake volume of the engine throttle valve to accurately reflect the intake flow of the engine; the second orifice plate flow meter 14 detects the gas flow entering the aftertreatment catalyst 17.

[0038] The control unit is electrically connected to the inlet flow meter 15, the first orifice plate flow meter 13, the second orifice plate flow meter 14, the temperature sensor 10, the first throttle valve 11, the second throttle valve 12, and the air supply valve 9-1 of the air storage tank. The control unit uses commercially available products, such as a small PLC with a built-in touchscreen. It can acquire data from the inlet flow meter 15, the first orifice plate flow meter 13, the second orifice plate flow meter 14, and the temperature sensor 10 through configuration rather than programming. Based on the acquired flow rate values ​​and preset control thresholds, it controls the opening or closing of the first throttle valve 11 and the second throttle valve 12 via the PLC's DO (Direct Operation Point). Similarly, based on the acquired temperature and preset control thresholds, it controls the opening or closing of the air supply valve 9-1 of the air storage tank via the PLC's DO.

[0039] While maintaining engine operating conditions, the diversion mechanism 3 is used to divert the engine exhaust gas source to adjust the exhaust flow rate of the exhaust gas source entering the catalyst, and control the fluctuation of the exhaust flow rate to be less than 0.5 g / s, with an exhaust flow rate control accuracy of less than 0.2 g / s. This allows for precise testing of the oxygen storage performance of the catalyst under different exhaust flow rates without adjusting the exhaust flow rate entering the catalyst by adjusting the engine operating conditions, thus maintaining the change in oxygen content in the exhaust gas, ensuring the accuracy of the oxygen storage test, and ultimately achieving precise benchmarking of oxygen storage with third-party testing institutions.

[0040] While maintaining engine operating conditions, the temperature control mechanism 4 is used to reduce the exhaust temperature at the catalyst inlet to control the temperature fluctuation of the exhaust gas source at the catalyst inlet to be less than ±10℃. In this embodiment, the temperature control mechanism 4 is connected to the inlet of the diversion mechanism 3. When the catalyst inlet temperature deviates from the target temperature during the stabilization process after the air-fuel ratio rich-lean switching, it is not necessary to adjust the engine operating conditions to regulate the catalyst inlet temperature. With the engine operating conditions remaining unchanged, the temperature control mechanism 4 precisely controls the temperature of the engine's exhaust gas source, reducing the temperature deviation of the catalyst inlet temperature caused by the excessively long stabilization time after the air-fuel ratio switching, so as to control the temperature fluctuation of the exhaust gas source at the catalyst inlet to be less than ±5℃, ensuring the accuracy of the oxygen storage test.

[0041] Example 2

[0042] like Figure 2 As shown, a gas flow rate adjustment method and an aftertreatment catalyst 17 inlet temperature control method for a shunting and temperature control device in an automotive catalyst oxygen storage capacity evaluation bench system are disclosed. The shunting mechanism 3 and temperature control device of Example 1 are used to shun the engine exhaust gas source to adjust the exhaust gas flow rate entering the catalyst, ensuring that the exhaust flow rate control accuracy is less than 0.2 g / s and that the exhaust gas source temperature fluctuation at the catalyst inlet is less than ±5℃. Specifically, the method includes the following steps:

[0043] 1) Start the hot engine and adjust the engine speed and throttle in real time to control the engine intake air flow at 40 kg / h, the inlet temperature of the aftertreatment catalyst 17 at 500℃, and the distance between the placement point of the temperature sensor 10 and the front end face of the carrier of the aftertreatment catalyst 17 is (100±10) mm.

[0044] 2) The second orifice plate flow meter 14 monitors the exhaust flow of the test pipeline at the inlet of the aftertreatment catalyst 17 and transmits the detected feedback flow to the control unit 1;

[0045] 3) Control unit 1 compares the exhaust flow rate and set flow rate of the test line 6 at the inlet of the aftertreatment catalyst 17;

[0046] 4) When the feedback flow rate is greater than the set flow rate, the control unit 1 opens the diversion mechanism and increases the opening of the first throttle valve 11 on the diversion pipeline 5, while decreasing the opening of the second throttle valve 12 on the test pipeline 6; when the feedback flow rate is less than the set flow rate, the opening of the first throttle valve 11 on the diversion pipeline 5 is decreased, while the opening of the second throttle valve 12 on the test pipeline 6 is increased.

[0047] 5) When the feedback flow reaches the set flow rate, maintain the opening of the first throttle valve 11;

[0048] 6) Adjust the engine ECU control system to achieve a rich state, i.e., λ=0.90 (or 0.95). After the test conditions stabilize for at least 20 seconds and the oxygen sensor voltage signal stabilizes, adjust the ECU control system to make λ lean, i.e., a sudden change occurs when λ=1.10 (or 1.05). The number of rich-lean switching operations should not be less than 10, and the changes in the oxygen sensor voltage signals before and after should be collected.

[0049] 7) Temperature sensor 10 monitors the temperature at the inlet of the post-treatment catalyst 17 and transmits the monitored feedback temperature to control unit 1;

[0050] 8) Control unit 1 compares the feedback temperature with the set temperature at the inlet of the aftertreatment catalyst 17;

[0051] 9) When the feedback temperature at the inlet of the aftertreatment catalyst 17 is greater than the set temperature, the control unit 1 opens the air supply valve 9-1 of the air storage tank and pumps air into the air storage tank through the electric air compressor. The air storage tank provides compressed air through the air supply valve 9-1 to purge and cool the heat dissipation fins 7.

[0052] 10) When the feedback temperature reaches the set temperature, the control unit 1 closes the gas supply valve 9-1 of the gas storage tank;

[0053] 11) Calculate the oxygen storage and release value of TWC by using the time of change of the voltage signal of the oxygen sensor before and after the abrupt change, as well as the change of the intake flow rate and λ during the abrupt change.

[0054] Example 3

[0055] Experiment on the effect of exhaust flow fluctuation on catalyst oxygen storage capacity

[0056] In this embodiment, a GM HT383E engine manufactured by General Motors was used to test the oxygen storage performance of a TWC catalyst for a gasoline engine. The carrier size was φ118.4*100 (mm), the pore size was 750 cpsi, and the loading of platinum in the catalyst was 0.318 g / L, palladium was 1,166 g / L, and rhodium was 0.106 g / L.

[0057] Experimental Procedure: The engine intake airflow and catalyst inlet temperature were controlled by adjusting engine speed and throttle. The flow splitter 3 of the automotive catalyst oxygen storage capacity evaluation bench system (Example 1) and the exhaust flow control method of the same system (Example 2) were used to scan the oxygen storage capacity at different exhaust flow rates. The experimental results are as follows: Figure 3 As shown;

[0058] Experimental results: From Figure 3 The results show that, while keeping the engine intake airflow at 40 kg / h and the catalyst inlet temperature at 500℃ constant, the oxygen storage capacity was tested by adjusting the exhaust flow rate through the second throttle valve on the splitter pipe of the splitter mechanism 3 and the first throttle valve on the test pipe under different exhaust flow rates. Starting from an exhaust flow rate of 9.7 g / s, the oxygen storage capacity changed by an average of 6% for every 1.5 g / s increase in exhaust flow rate. As the exhaust flow rate increased, the space velocity of the chemical reaction of the catalyst increased, leading to a decreasing trend in oxygen storage capacity. However, by adjusting the required exhaust flow rate using the splitter mechanism 3, the fluctuation of the exhaust flow rate was less than or equal to 0.2 g / s, reducing the deviation of oxygen storage capacity to within 3%, effectively reducing the deviation of oxygen storage capacity caused by exhaust flow rate fluctuations.

[0059] Example 4

[0060] The oxygen storage capacity test was conducted using the flow splitting mechanism 3 of the catalyst oxygen storage capacity engine bench evaluation system of Example 1 and the exhaust flow control method of the catalyst oxygen storage capacity engine bench evaluation system of Example 2. The differences between the two were compared between the two systems with and without the flow splitting mechanism (single pipe structure).

[0061] This embodiment uses a GM HT383E engine manufactured by General Motors to test the oxygen storage performance of a TWC dual-catalyst combination for gasoline engines. The front-stage TWC carrier has a size of φ118.4*50 (mm) and a pore size of 600 cpsi, with a palladium loading of 1.068 g / L and a rhodium loading of 0.039 g / L. The rear-stage TWC carrier has a size of φ118.4*100 (mm) and a pore size of 400 cpsi, with a platinum loading of 0.194 g / L and a rhodium loading of 0.077 g / L.

[0062] The experimental procedure was as follows: First, the engine was started, and the engine speed and throttle were adjusted in real time to achieve a catalyst inlet temperature of 500℃ and an intake air flow rate of 40 kg / h. The excess air coefficient (λ) was adjusted to a slightly rich state (λ = 0.95) by adjusting the engine ECU control unit. After the test conditions stabilized for 40 seconds until the oxygen sensor voltage signal stabilized, the engine ECU control unit was adjusted to make λ lean, i.e., a sudden change occurred when λ = 1.05, and the changes in the voltage signals of the front and rear oxygen sensors were collected. Using the collected changes in the voltage signals of the front and rear oxygen sensors over time, as well as the intake air flow rate and the change in λ during the sudden change, the oxygen storage capacity of the TWC was calculated. The experiment was repeated at least 10 times, and the arithmetic mean was calculated.

[0063] Table 1 shows the test conditions and results for different exhaust pipe structures and exhaust flow control methods of engine bench evaluation systems with different catalyst oxygen storage capacities.

[0064] Table 1

[0065]

[0066] As shown in Table 1, the oxygen storage capacity was 996 mg / L under the single-tube structure test and 1978 mg / L under the split-flow mechanism test. The split-flow mechanism improved the oxygen storage capacity by approximately 98% compared to the single-tube structure, and the deviation from the target value was reduced to approximately 4%, achieving the required oxygen storage capacity. This indicates that the split-flow mechanism can accurately control the engine exhaust gas source to reach the set value, while the fluctuation of exhaust flow during the oxygen storage capacity test is very small, less than or equal to 0.2 g / s; thus ensuring the accuracy of the oxygen storage capacity. This solves the problem of low oxygen storage capacity caused by excessive exhaust flow due to differences in engine model, displacement, and fuel consumption when testing oxygen storage capacity with large-displacement engines, thereby achieving the benchmarking requirements of third-party testing institutions.

[0067] Example 5

[0068] The temperature control mechanism of the automotive catalyst oxygen storage capacity evaluation test bench system of Example 1 is adopted, and the temperature control method of the automotive catalyst oxygen storage capacity evaluation test bench system of Example 2 is adopted.

[0069] This embodiment uses a GM HT383E engine manufactured by General Motors to test the oxygen storage performance of a TWC dual-catalyst combination for gasoline engines. The front-stage TWC carrier has dimensions of φ118.4*50 (mm) and a pore size of [missing information].

[0070] The catalyst has a loading of 600 cpsi, with palladium loading of 1.068 g / L and rhodium loading of 0.039 g / L; the downstream TWC support has a size of φ118.4*100 (mm) and a mesh size of 400 cpsi, with platinum loading of 0.194 g / L and rhodium loading of 0.077 g / L.

[0071] The experimental procedure was as follows: First, the engine was started, and the engine speed and throttle were adjusted in real time to achieve a catalyst inlet temperature of 500℃ and an intake air flow rate of 40 kg / h. The excess air coefficient (λ) was adjusted to a slightly rich state (λ = 0.95) by adjusting the engine ECU control unit. After the test conditions stabilized for 40 seconds until the oxygen sensor voltage signal stabilized, the engine ECU control unit was adjusted to make λ lean, i.e., a sudden change occurred when λ = 1.05, and the changes in the voltage signals of the front and rear oxygen sensors were collected. Using the collected changes in the voltage signals of the front and rear oxygen sensors over time, as well as the intake air flow rate and the change in λ during the sudden change, the oxygen storage capacity of the TWC was calculated. The experiment was repeated at least 10 times, and the arithmetic mean was calculated.

[0072] The test conditions and results are shown in Table 2, with and without a temperature control system for evaluating the oxygen storage capacity of automotive catalysts.

[0073] Table 2

[0074]

[0075] As can be seen from Table 2, after adding the temperature control mechanism, the deviation of the catalyst inlet temperature was reduced from ±15℃ to ±5℃. The catalyst inlet temperature was controlled, and the catalyst inlet temperature would not keep rising when the air-fuel ratio switched to the lean zone and stabilized, thus reducing the deviation of oxygen storage from the original 13% to less than 4%.

Claims

1. A temperature control device for a flow splitting of an evaluation bench system for the oxygen storage capacity of automotive catalysts, characterized by It includes an execution unit and a control unit (1); the execution unit is connected to the exhaust manifold outlet of the engine; the execution unit includes a flow splitting mechanism (3) and a temperature control mechanism (4); the control unit (1) is used to control the operation of the execution unit; A diversion pipe (5) is set at the end of the test pipe (6) connecting the engine (16) and the aftertreatment catalyst (17) near the engine (16); the exhaust gas source on the exhaust pipe is diverted by the test pipe (6) and the diversion pipe (5) set in parallel. When the required exhaust flow rate is small, more gas flows into the diversion pipe (5), and when the required exhaust flow rate is large, more gas flows into the test pipe (6). By controlling the gas flow rate on the two pipes, the exhaust flow rate entering the catalyst is controlled, so that the control of the exhaust flow rate is more accurate and stable, which is used to ensure the stability of the oxygen storage test. The temperature control mechanism (4) includes an air supply device and heat dissipation fins (7); the heat dissipation fins (7) cover the front end of the test pipeline (6) and the post-treatment catalyst (17); the air supply device consists of an electric air compressor (8) connected to an air storage cylinder (9), the air storage cylinder (9) supplies compressed air to the heat dissipation fins (7) through the air supply valve (9-1) of the air storage cylinder, and the airflow in the test pipeline (6) is controlled by blowing compressed air into the heat dissipation fins (7); a temperature sensor (10) is provided in the test pipeline (6) between the heat dissipation fins (7) and the post-treatment catalyst (17) to measure the air temperature in the test pipeline (6) at the inlet of the post-treatment catalyst (17); The execution unit also includes an intake flow meter (15), a first orifice plate flow meter (13), and a second orifice plate flow meter (14): the intake flow meter (15) is installed at the inlet of the engine intake manifold; the first orifice plate flow meter (13) and the second orifice plate flow meter (14) are respectively installed after the first throttle valve (11) and the second throttle valve (12); the intake flow meter (15) is a thermal gas flow meter used to detect the intake volume of the engine throttle valve to accurately reflect the intake flow of the engine; the second orifice plate flow meter (14) detects the gas flow entering the aftertreatment catalyst (17); The control unit (1) is electrically connected to the inlet flow meter (15), the first orifice plate flow meter (13), the second orifice plate flow meter (14), the temperature sensor (10), the first throttle valve (11), the second throttle valve (12), and the gas supply valve (9-1) of the gas storage tank.

2. The shunt temperature control device for an automotive catalyst oxygen storage capacity evaluation bench system according to claim 1, characterized in that: The test pipeline (6) is horizontally connected to the engine exhaust manifold outlet, and the connection between the branch pipeline (5) and the test pipeline (6) is at a 45-degree angle to ensure the uniformity of the gas flow field in the test pipeline (6).

3. The shunt temperature control device for an automotive catalyst oxygen storage capacity evaluation bench system according to claim 1, characterized in that: The throttle valves of the test line (6) and the diversion line (5) are both set to be in a state that cannot be completely closed, so that at least 10 kg / h of airflow can pass through, to prevent the engine from stalling due to poor exhaust due to the test line (6) and the diversion line (5) being completely closed.

4. The shunt temperature control device for an automotive catalyst oxygen storage capacity evaluation bench system according to claim 1, characterized in that: When the temperature is higher than the target temperature, the control unit (1) controls the inlet temperature of the post-treatment catalyst (17) by opening or closing the gas supply valve (9-1) of the gas storage tank and blowing the heat dissipation fins (7) with compressed air.

5. The shunt temperature control device for an automotive catalyst oxygen storage capacity evaluation bench system according to claim 1, characterized in that: The control unit (1) is a PLC.

6. The shunt temperature control device for an automotive catalyst oxygen storage capacity evaluation bench system according to claim 5, characterized in that: By configuring the PLC, data acquisition is realized from the inlet flow meter (15), the first orifice plate flow meter (13), the second orifice plate flow meter (14), and the temperature sensor (10). The first throttle valve (11) and the second throttle valve (12) are opened or closed according to the acquired flow value and the preset control threshold. The gas supply valve (9-1) of the gas storage tank is opened or closed according to the acquired temperature and the preset control threshold.

7. The shunt temperature control device for an automotive catalyst oxygen storage capacity evaluation bench system according to any one of claims 1-6, characterized in that: The temperature sensor (10) is positioned at a distance of 100±10 mm from the front end of the carrier of the post-treatment catalyst (17).

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