Three-way catalytic converter temperature and overheating protection method, device, electronic equipment and vehicle

Abstract

The present invention discloses a three-way catalytic converter temperature and overheat protection method, device, electronic device and vehicle, comprising: step 1: obtaining the current working condition information of the engine, including the exhaust mass flow, the three-way catalytic converter inlet temperature and the fuel-air ratio under the current working condition; step 2: protecting the three-way catalytic converter temperature based on the engine working condition information obtained in step 1, limiting the enriched fuel-air ratio before the engine enters the fuel cut-off condition, and limiting the clean oxygen enriched fuel-air ratio after the engine resumes the fuel supply condition, so that the three-way catalytic converter temperature T is lower than its temperature limit T1; step 3: judging whether to trigger the overheat protection function of the three-way catalytic converter, if T>T1, then triggering the overheat protection function. The present invention limits the enriched fuel-air ratio before the fuel cut-off according to the current temperature of the three-way catalytic converter, limits the clean oxygen enriched fuel-air ratio after the fuel supply is resumed, and performs overheat protection after the temperature of the three-way catalytic converter exceeds the limit, so as to achieve the temperature and overheating limit of the three-way catalytic converter.

Description

Technical Field

[0001] The present invention relates to the technical field of control of engine exhaust purification treatment, and in particular to a three-way catalytic converter temperature and overheating protection method, device, electronic equipment and vehicle Background Art

[0002] The three-way catalytic converter is an important external purification device in the exhaust system of natural gas engines. The coated precious metal Pt / Pd / Rh can be used as a catalyst to enhance the activity of three gases, CO, HC and NOx, within a certain temperature range, and oxidize and reduce the harmful gases discharged from the automobile exhaust into harmless CO2, water and nitrogen. There are two main factors that affect the conversion efficiency of the three-way catalytic converter: one is the engine's rich-lean switching operation near the theoretical fuel-air ratio; the other is whether the activity of the three-way catalytic converter is good.

[0003] The main reasons for the reduction of the activity of the three-way catalytic converter are poisoning degradation and overheating degradation. The former is mainly related to the fuel composition, and the latter is mainly related to the working temperature of the three-way catalytic converter. The precious metal coating of the three-way catalytic converter is usually composed of platinum, palladium, rhodium, etc. The precious metal coating is distributed on the three-way catalytic converter carrier in the form of nano-sized particles. When the engine exhaust temperature is high, or the reaction heat generated when the three-way catalytic converter is working is high, the temperature of the three-way catalytic converter will rise rapidly. When the temperature of the three-way catalytic converter exceeds 1000°C, the precious metals such as platinum, palladium, and rhodium in the catalyst coating on the carrier will sinter or fall off due to high temperature, so that the chemical reaction cannot proceed normally, and in severe cases, it will also cause vehicle spontaneous combustion accidents. Therefore, avoiding excessive temperature of the three-way catalytic converter and preventing overheating and degradation of the three-way catalytic converter have become key issues affecting the working efficiency and life of the three-way catalytic converter.

[0004] The temperature of the three-way catalytic converter is mainly affected by two factors. One is the exhaust temperature of the engine. The exhaust temperature mainly affects the temperature of the three-way catalytic converter through the heat transfer process. There are many factors that affect the exhaust temperature of the engine, such as ignition advance angle lag, oil-gas mixing imbalance, etc., which will cause the exhaust temperature to rise. Excessive exhaust temperature has an impact on the components on the entire exhaust path. At present, there are technologies that achieve overheating protection of components by controlling the exhaust temperature. The second is the exothermic reaction in the three-way catalytic converter. The exothermic oxidation reaction when the three-way catalytic converter is working is another reason for the increase in the temperature of the three-way catalytic converter. Usually, the limit temperature of the three-way catalytic converter is caused by the frequent switching of oil cut-off and oil supply: during the short oil cut-off period, the ambient air is blown through the catalyst, and the three-way catalytic converter will be in a state of full oxygen storage; when the three-way catalytic converter is full of oxygen, the fuel supply is restored. On the one hand, it is necessary to enrich the combustion to clear the oxygen storage of the three-way catalytic converter and restore the ability of the three-way catalytic converter to reduce NOx; on the other hand, the components that are not completely burned after enrichment (CO, HC, etc.) will undergo rapid and violent oxidation reactions when the three-way catalytic converter is rich in oxygen storage, and the temperature of the three-way catalytic converter will rise rapidly.

[0005] Prior art solution 1: A device for preventing a three-way catalytic converter from being damaged by overheating (patent number: 202111531783.2), which discloses a device for preventing a three-way catalytic converter from being damaged by overheating, and the device includes a structural frame, an expansion airbag, an inflatable structure, and a cooling chamber. A drain pipe is wound around the surface of the three-way catalytic converter, and the water pump drives the liquid in the drain pipe to flow, thereby taking away the heat of the three-way catalytic converter to the cooling chamber. The temperature of the cooling chamber rises, and through heat transfer, the expansion airbag expands due to heat, and the inflatable structure is squeezed to generate gas that blows toward the cooling chamber to cool the liquid inside the cooling chamber. The above scheme uses a physical cooling method of water cooling and air cooling to achieve the purpose of cooling the three-way catalytic converter. The entire device includes a structural frame, an expansion airbag, an inflatable structure, a cooling chamber, and cooling water. The implementation process is that when the temperature of the three-way catalytic converter is high, the airbag is heated and expanded through heat conduction, and the sliding rod is squeezed to drive the lever to rotate and squeeze the piston air chamber, generating gas that blows toward the cooling chamber for cooling. On the one hand, when the three-way catalytic converter is overheated, there will be a certain delay in expanding the airbag to provide the required amount of gas through heat conduction, and the three-way catalytic converter cannot be cooled in time; on the other hand, the device has more components, which increases the difficulty of installation and layout of the vehicle's after-treatment system and increases hardware costs.

[0006] Prior art solution 2: A gas engine three-way catalytic converter overheating protection system (patent number: 202022454249.3), which provides a gas engine three-way catalytic converter overheating protection system, which is equipped with a temperature sensor, a methane concentration sensor and two solenoid valves in the exhaust pipe. The controller monitors the feedback signal of the sensor in real time. When the exhaust temperature is too high, it controls the on-off of the two solenoid valves to realize the direction of the airflow in the exhaust pipe, reduce the exhaust flow entering the three-way catalytic converter, and thus realize overheating protection of the three-way catalytic converter. The above solution realizes overheating protection of the three-way catalytic converter by changing the mass flow rate of the exhaust gas entering the three-way catalytic converter. The whole device includes two solenoid valves, a temperature sensor and a methane concentration sensor, and a bypass pipe is required in the exhaust pipe. When the three-way catalytic converter is overheated, the exhaust mass flow entering the three-way catalytic converter is reduced by controlling the on-off of the solenoid valve. On the one hand, the exhaust gas discharged through the bypass pipe has not been processed by the three-way catalytic converter, which may cause the risk of substandard emissions; on the other hand, like the above-mentioned solution 1, the device has many components, which increases the hardware cost. Summary of the invention

[0007] In order to avoid the overheating of the three-way catalytic converter during vehicle operation, this paper proposes a three-way catalytic converter temperature and overheating protection method and device. The method of the present invention can limit the enriched fuel-air ratio before fuel cut-off according to the current temperature of the three-way catalytic converter, limit the oxygen-free enriched fuel-air ratio after resuming fuel supply, and perform overheating protection after the temperature of the three-way catalytic converter exceeds the limit value, thereby achieving temperature and overheating restrictions on the three-way catalytic converter.

[0008] To solve the above technical problems, the present invention is implemented through the following technical solutions:

[0009] A method for temperature and overheat protection of a three-way catalytic converter, comprising the following steps:

[0010] Step 1: Obtain the current operating condition information of the engine, including the exhaust mass flow rate, the inlet temperature of the three-way catalytic converter, and the fuel-air ratio under the current operating condition;

[0011] Step 2: Protect the temperature of the three-way catalytic converter based on the engine operating condition information obtained in Step 1. Limit the enriched fuel-air ratio before the engine enters the fuel cut-off operating condition, and limit the oxygen cleaning enriched fuel-air ratio after the engine resumes the fuel supply operating condition, so that the temperature T of the three-way catalytic converter is lower than its temperature limit value T1;

[0012] Step 3: Determine whether to trigger the overheat protection function for the three-way catalytic converter. If T>T1, trigger the overheat protection function.

[0013] Preferably, the method for limiting the enriched fuel-air ratio before the engine enters the fuel cut-off operating condition is as follows:

[0014] 1) When a fuel cut-off request is received, determine whether the current fuel-air ratio is greater than the threshold r0. If so, set the fuel cut-off request prohibition identifier to 1, prohibit fuel cut-off, and set the fuel-air ratio of the current operating condition to the stoichiometric ratio r1 of the fuel-air ratio, and directly proceed to the next step; if not, set the fuel cut-off request prohibition identifier to 0 and allow fuel cut-off;

[0015] 2) Determine whether the current fuel-air ratio has reached the stoichiometric ratio r1 of the fuel-air ratio. If so, set the fuel cut-off request prohibition identifier to 0 and allow fuel cut-off; if not, continue to wait until the fuel-air ratio reaches the stoichiometric ratio r1 and then allow fuel cut-off.

[0016] Further preferably, the fuel-air ratio threshold r0 is obtained according to the three-way catalytic converter temperature MAP. The higher the temperature of the three-way catalytic converter, the closer the fuel-air ratio threshold r0 is to the stoichiometric ratio r1 of the fuel-air ratio.

[0017] Preferably, the method for limiting the oxygen cleaning enriched fuel-air ratio after the engine resumes the fuel supply operating condition is as follows:

[0018] When oxygen cleaning enabling of the three-way catalytic converter is recognized after fuel supply is resumed, determine whether to limit the oxygen cleaning enriched fuel-air ratio according to the temperature T of the three-way catalytic converter and the critical temperature T0:

[0019] 1) When T<T0, the temperature of the three-way catalytic converter has not reached the critical temperature and there is no overheat risk. Use the oxygen cleaning enriched fuel-air ratio r calculated according to the current operating condition for enriched combustion;

[0020] 2) When T > T0, the temperature of the three-way catalytic converter is relatively high, and there is a risk of overheating. It is necessary to limit the lean-oxygen enrichment air-fuel ratio r using the maximum air-fuel ratio r2 for lean-oxygen cleaning allowed under the current working conditions: when r < r2, the lean-oxygen enrichment air-fuel ratio uses r; when r > r2, the lean-oxygen enrichment air-fuel ratio uses r2; where T0 < T1.

[0021] Preferably, in step 2), according to the temperature of the three-way catalytic converter and the exhaust mass flow rate, map out the maximum air-fuel ratio r2 for lean-oxygen cleaning to avoid overheating of the catalytic converter under the current working conditions.

[0022] Preferably, in step 3, the method for the overheat protection function of the three-way catalytic converter is as follows:

[0023] 1) Set the temperature limit value T1 for triggering the overheat protection of the three-way catalytic converter and the temperature limit value T2 for exiting the overheat protection, where T1 > T2;

[0024] 2) Determine whether the temperature of the three-way catalytic converter is greater than the temperature limit value T1. If it is, set the prohibited fuel cut request identifier to 1, request the engine to prohibit fuel cut, and perform overheat protection; if not, proceed to the next step;

[0025] 3) Determine whether the temperature of the three-way catalytic converter is less than the temperature limit value T2. When the temperature of the three-way catalytic converter is less than the temperature limit value T2, determine whether the prohibited fuel cut request identifier in the previous sampling period is 1 and whether the output torque at the engine crankshaft end is less than the threshold value. If it is, maintain the prohibited fuel cut request; if the prohibited fuel cut request identifier in the previous sampling period is 0, or the output torque at the engine crankshaft end is greater than the threshold value, exit the overheat protection function of the three-way catalytic converter and set the prohibited fuel cut request identifier to 0; when the temperature of the three-way catalytic converter is greater than the temperature limit value T2, maintain the prohibited fuel cut request.

[0026] A device for the temperature and overheat protection of a three-way catalytic converter, the protection device includes an engine electronic control unit and a temperature sensor, a front oxygen sensor, and a rear oxygen sensor electrically connected to the engine electronic control unit. The temperature sensor is arranged between the three-way catalytic converter and the engine and is used to detect the exhaust temperature of the engine; the front oxygen sensor is arranged between the three-way catalytic converter and the engine and is used to detect the exhaust oxygen content of the engine; the rear oxygen sensor is arranged at the outlet of the three-way catalytic converter and is used to detect the exhaust oxygen content of the three-way catalytic converter; the engine electronic control unit is used to perform temperature and overheat protection control on the three-way catalytic converter according to the data detected by the temperature sensor, the front oxygen sensor, and the rear oxygen sensor.

[0027] An electronic device includes a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, it implements the method for the temperature and overheat protection of the three-way catalytic converter as described in the above technical solution.

[0028] A computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the three-way catalytic converter temperature and overheating protection method as described in the above technical solution is implemented.

[0029] A vehicle comprises a three-way catalytic converter temperature and overheating protection device as described in the above technical solution.

[0030] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0031] The present invention realizes temperature protection of the three-way catalytic converter by controlling the heat release and heat release rate of the reaction in the three-way catalytic converter; specifically, the heat release and heat release rate of the exothermic reaction in the three-way catalytic converter are controlled by limiting the enriched fuel-air ratio before the engine oil is cut off, limiting the oxygen-clearing and enriched fuel-air ratio according to the temperature of the three-way catalytic converter after the oil supply is restored, and overheat protection after the three-way catalytic converter is overheated, so as to achieve the purpose of controlling the catalyst temperature.

[0032] The protection device of the present invention has relatively few components, which reduces the difficulty of installation and layout of the vehicle after-treatment system and reduces the hardware cost.

[0033] In the present invention, when it is identified that there is a risk of overheating of the catalyst, the fuel-air ratio of the current operating condition will be limited in time to reduce the heat release rate of the chemical reaction in the catalyst, thereby effectively avoiding overheating of the catalyst.

[0034] The present invention does not bypass the exhaust gas, and the exhaust gas is discharged after being processed by the three-way catalytic converter, so there is no risk of substandard emissions. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 The natural gas engine post-treatment exhaust system of the present invention;

[0036] Figure 2 A flow chart of limiting the enrichment of the fuel-air ratio before the fuel cut-off of the engine of the present invention;

[0037] Figure 3 This is a flow chart of limiting the oxygen-clearing and enriching fuel-air ratio after resuming fuel supply according to the present invention;

[0038] Figure 4 The figure is a flow chart of overheat protection after overheating of the three-way catalytic converter of the present invention.

[0039] Figure numerals: 1-engine electronic control unit; 2-three-way catalytic converter; 3-temperature sensor; 4-front oxygen sensor; 5-rear oxygen sensor. DETAILED DESCRIPTION

[0040] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0041] The embodiments of the present invention are further described in detail below with reference to the accompanying drawings.

[0042] The embodiments of the present invention provide a three-way catalytic converter temperature and overheating protection method, device, electronic device, storage medium and vehicle to achieve three-way catalytic converter temperature and overheating protection.

[0043] In order to achieve the above technical effects, the overall idea of ​​the present invention is as follows:

[0044] A three-way catalytic converter temperature and overheat protection method comprises the following steps:

[0045] Step 1: Obtain the current operating condition information of the engine, including exhaust mass flow, three-way catalytic converter inlet temperature, and fuel-air ratio under the current operating condition.

[0046] Step 2: a) Limiting the enrichment of the fuel-air ratio unit before the engine is cut off

[0047] Under certain operating conditions (such as resuming fuel supply after an Overrun state), the engine will use a large fuel-air ratio for enriched combustion to ensure sufficient combustion of a small amount of air charge. If the fuel is cut off during this period, at the moment of fuel cut-off, the unburned fuel components will react with the subsequent air in the three-way catalytic converter, causing the temperature of the three-way catalytic converter to rise. To avoid the rise in the temperature of the three-way catalytic converter in this case, when the temperature of the three-way catalytic converter is higher than the threshold, the enriched fuel-air ratio must be restored to the chemical reaction dosage ratio before the fuel cut-off is allowed.

[0048] Based on the engine operating condition information obtained in step 1, the temperature of the three-way catalyst is protected, the enriched fuel-air ratio is limited before the engine enters the fuel cut-off condition, and the oxygen-free enriched fuel-air ratio is limited after the engine resumes the fuel supply condition, so that the temperature T of the three-way catalyst is lower than its temperature limit T1;

[0049] The specific implementation process is as follows Figure 2 As shown:

[0050] 1) When a fuel cut-off request is received, determine whether the current air-fuel ratio is greater than the threshold r0. If so, set the fuel cut-off request prohibition identifier to 1, prohibit fuel cut-off, set the air-fuel ratio of the current working condition to the stoichiometric ratio r1 of the air-fuel ratio, and directly proceed to the next step; if not, set the fuel cut-off request prohibition identifier to 0 and allow fuel cut-off; the air-fuel ratio threshold r0 is obtained according to the three-way catalytic converter temperature MAP. The higher the three-way catalytic converter temperature, the closer the air-fuel ratio threshold r0 is to the stoichiometric ratio r1 of the air-fuel ratio.

[0051] 2) Determine whether the current air-fuel ratio has reached the stoichiometric ratio r1 of the air-fuel ratio. If so, set the fuel cut-off request prohibition identifier to 0 and allow fuel cut-off; if not, continue to wait until the air-fuel ratio reaches the stoichiometric ratio r1 and then allow fuel cut-off.

[0052] b) Restrict the oxygen cleaning enrichment air-fuel ratio unit after fuel supply is restored

[0053] When fuel supply is restored after a short fuel cut-off, the engine will request a larger air-fuel ratio for rich combustion to remove the oxygen storage in the three-way catalytic converter and restore the conversion efficiency of the three-way catalytic converter. The higher the enrichment air-fuel ratio during oxygen cleaning, the higher the oxygen cleaning rate, and the faster the three-way catalytic converter can restore the ability to convert NOx. However, a large oxygen cleaning enrichment air-fuel ratio will cause a more intense oxidation reaction in the three-way catalytic converter, and the temperature of the three-way catalytic converter will also rise rapidly. Therefore, it is necessary to limit the enrichment air-fuel ratio during the oxygen cleaning process according to the temperature and exhaust mass flow rate of the three-way catalytic converter under the current working condition, thereby controlling the reaction rate of the three-way catalytic converter and avoiding exceeding the temperature limit of the three-way catalytic converter.

[0054] The specific implementation process is as Figure 3 shown:

[0055] When it is recognized that the three-way catalytic converter oxygen cleaning is enabled after fuel supply is restored, determine whether to limit the oxygen cleaning enrichment air-fuel ratio according to the three-way catalytic converter temperature T and the critical temperature T0:

[0056] 1) When T < T0 (about 600 degrees), the temperature of the three-way catalytic converter has not reached the critical temperature, and there is no overheating risk. Rich combustion is carried out using the oxygen cleaning enrichment air-fuel ratio r calculated according to the current working condition;

[0057] 2) When T > T0, the temperature of the three-way catalytic converter is relatively high, and there is an overheating risk. It is necessary to limit the oxygen cleaning enrichment air-fuel ratio r; where T0 < T1; the maximum oxygen cleaning enrichment air-fuel ratio r2 allowed by the current working condition is used to limit the oxygen cleaning enrichment air-fuel ratio r: when r < r2, the oxygen cleaning enrichment air-fuel ratio is r; when r > r2, the oxygen cleaning enrichment air-fuel ratio is r2.

[0058] Calculation of the limit value of the oxygen cleaning enrichment air-fuel ratio:

[0059] According to the temperature of the three-way catalytic converter and the exhaust mass flow rate, MAP outputs the maximum oxygen-free fuel-air ratio r2 to avoid overheating of the three-way catalytic converter under the current working conditions. The following 1) and 2) give the method of r2 according to the catalyst temperature and exhaust mass flow rate MAP (look up the table, the table is the relationship between r2 and the catalyst temperature and exhaust mass flow rate, which can be calibrated through bench tests), that is, the higher the temperature and the greater the exhaust mass flow rate, the smaller r2; the lower the temperature and the smaller the exhaust mass flow rate, the larger r2.

[0060] 1) When the temperature of the three-way catalytic converter is higher and the exhaust mass flow rate is larger, the maximum fuel-air ratio r2 allowed in the oxygen removal process is smaller, so as to extend the reaction time of the oxygen removal process, reduce the energy of the reaction heat transfer to the three-way catalytic converter per unit time, and limit the temperature rise of the three-way catalytic converter;

[0061] 2) When the temperature of the three-way catalytic converter is lower and the exhaust mass flow rate is smaller, the risk of overheating of the three-way catalytic converter caused by the heat released by the three-way catalytic converter during oxygen removal is reduced, and the maximum fuel-air ratio r2 allowed during the oxygen removal process is larger.

[0062] Step 3: When the temperature of the three-way catalytic converter is approaching the limit temperature that the three-way catalytic converter can withstand, in order to avoid repeated oil cut-off and oil recovery that further increases the temperature of the three-way catalytic converter, the engine needs to be requested to prohibit oil cut-off under this condition to protect the three-way catalytic converter from overheating. In this method, whether to trigger the three-way catalytic converter overheating protection function is determined based on the three-way catalytic converter temperatures T and T1.

[0063] The specific implementation process is as follows Figure 4 As shown:

[0064] 1) Set the temperature limit T1 for triggering the overheat protection of the three-way catalytic converter and the temperature limit T2 for exiting the overheat protection, T1>T2; usually the normal working temperature range of the catalyst is 400℃~800℃. When the temperature of the three-way catalytic converter exceeds 850℃, its catalytic activity will decrease. When the temperature exceeds 1000℃, the precious metal components of the catalyst will sinter or fall off. The temperature limit T1 for the overheat protection of the three-way catalytic converter should be lower than the limit temperature of the three-way catalytic converter burning out. T1 can be set to 900℃ to leave a control margin for the overheat protection function of the three-way catalytic converter; the temperature limit T2 for exiting the overheat protection can be set to 820℃ to avoid frequent entry and exit of the overheat protection function of the three-way catalytic converter;

[0065] 2) Determine whether the temperature of the three-way catalytic converter is greater than the temperature limit T1. If so, set the fuel cut-off prohibition request identifier to 1 to request the engine to prohibit fuel cut-off for overheat protection; if not, proceed to the next step;

[0066] 3) Determine whether the temperature of the three-way catalytic converter is less than the temperature limit T2. When the temperature of the three-way catalytic converter is less than the temperature limit T2, determine whether the prohibition of fuel cut-off request identifier of the previous sampling cycle is 1, and whether the output torque of the engine crankshaft end is less than the threshold value (usually set to 0). If so, maintain the prohibition of fuel cut-off request (this is because when the prohibition of fuel cut-off identifier of the previous sampling cycle is 1, it means that the temperature of the three-way catalytic converter is still very high; and when the output torque of the engine crankshaft end is less than the threshold value 0, the combustion in the cylinder is unstable, and unburned HC and CO will enter the three-way catalytic converter. If fuel cut-off is allowed at this time, a large amount of oxygen and unburned HC react in the three-way catalytic converter, causing the temperature of the three-way catalytic converter to rise. Therefore, the prohibition of fuel cut-off request is maintained in this case;); if the prohibition of fuel cut-off request identifier of the previous sampling cycle is 0, or the output torque of the engine crankshaft end is greater than the threshold value, the three-way catalytic converter overheating protection function is exited, and the prohibition of fuel cut-off request identifier is set to 0; when the temperature of the three-way catalytic converter is greater than the temperature limit T2, maintain the prohibition of fuel cut-off request.

[0067] Based on the same inventive concept as the embodiment of the three-way catalytic converter temperature and overheating protection method, the embodiment of the present invention provides a three-way catalytic converter temperature and overheating protection device, the protection device includes an engine electronic control unit 1 and a temperature sensor 3, a front oxygen sensor 4 and a rear oxygen sensor 5 electrically connected to the engine electronic control unit 1, the temperature sensor 3 is arranged between the three-way catalytic converter 2 and the engine, and is used to detect the exhaust temperature of the engine; the front oxygen sensor is arranged between the three-way catalytic converter and the engine, and is used to detect the exhaust oxygen content of the engine; the rear oxygen sensor is arranged at the outlet of the three-way catalytic converter, and is used to detect the exhaust oxygen content of the three-way catalytic converter; the engine electronic control unit is used to control the temperature and overheating protection of the three-way catalytic converter according to the data detected by the temperature sensor, the front oxygen sensor and the rear oxygen sensor.

[0068] Among them, the three-way catalytic converter is the exhaust gas purification system of the engine, which oxidizes and reduces the harmful gases discharged from the car's exhaust into harmless CO2, water and nitrogen.

[0069] The temperature sensor is used to detect the exhaust temperature upstream of the three-way catalytic converter and transmit the detection data to the engine electronic control unit for evaluating the current carrier temperature of the three-way catalytic converter.

[0070] The front oxygen sensor is used to detect the oxygen content in the engine exhaust pipe and transmit the detection data to the engine electronic control unit to obtain the actual fuel-air ratio of the current operating conditions and perform closed-loop correction on the fuel.

[0071] Rear oxygen sensor: It is used to detect the richness or leanness of the exhaust gas after passing through the three-way catalytic converter, and transmit the detection data to the engine electronic control unit to diagnose the conversion efficiency of the three-way catalytic converter.

[0072] The engine electronic control unit (ECU) is used to receive various data information of the engine, calculate and monitor the behavior. For this solution, the ECU is used as the carrier of the method, and mainly realizes the following functions: 1) receiving the current working condition information of the engine, including the exhaust mass flow, the inlet temperature of the three-way catalytic converter and the fuel-air ratio under the current working condition; 2) controlling the temperature and overheating protection of the three-way catalytic converter according to the engine working condition information and the temperature of the three-way catalytic converter carrier.

[0073] Based on the same inventive concept as the embodiment of the three-way catalytic converter temperature and overheating protection method, an embodiment of the present invention provides an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the three-way catalytic converter temperature and overheating protection method as described in the above technical solution when executing the computer program.

[0074] Based on the same inventive concept as the embodiment of the three-way catalytic converter temperature and overheating protection method, an embodiment of the present invention provides a computer-readable storage medium, which stores a computer program. When the computer program is executed by a processor, it implements the three-way catalytic converter temperature and overheating protection method as described in the above technical solution.

[0075] Based on the same inventive concept as the embodiment of the three-way catalytic converter temperature and overheating protection device, an embodiment of the present invention provides a vehicle, including a three-way catalytic converter temperature and overheating protection device as described in the above technical solution.

[0076] A person skilled in the art can understand that all or part of the processes in the above-mentioned embodiments can be implemented by instructing the relevant hardware through a computer program, and the computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above-mentioned methods. Among them, any reference to a memory, a database or other medium used in the embodiments provided by the present invention can include at least one of a non-volatile and a volatile memory.

[0077] The technical features of the engine electronic control unit, temperature sensor, front oxygen sensor and rear oxygen sensor described in the present invention (constituent units / elements of the present invention) are obtained from conventional commercial channels or prepared by conventional methods unless otherwise specified. Their specific structures, working principles, and possible control methods and spatial layout methods can be selected conventionally in the art and should not be regarded as the innovative points of the present invention. They are understandable to those skilled in the art and will not be further elaborated in detail in the patent of the present invention.

[0078] The above is only a specific embodiment of the present invention, so that those skilled in the art can understand or implement the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but should conform to the widest scope consistent with the principles and novel features invented herein.

Claims

1. A three-way catalytic converter temperature and overheating protection method, characterized in that: It includes the following steps: Step 1: Obtain the current operating condition information of the engine, including the exhaust mass flow rate, the temperature at the inlet of the three-way catalytic converter, and the fuel-air ratio under the current operating condition; Step 2: Protect the temperature of the three-way catalytic converter based on the engine operating condition information obtained in Step 1. Limit the rich fuel-air ratio before the engine enters the fuel cut-off operating condition, and limit the oxygen cleaning rich fuel-air ratio after the engine resumes the fuel supply operating condition, so that the temperature T of the three-way catalytic converter is lower than its temperature limit value T1; Step 3: Determine whether to trigger the overheat protection function for the three-way catalytic converter. If T>T1, trigger the overheat protection function; The method of limiting the oxygen cleaning rich fuel-air ratio after the engine resumes the fuel supply operating condition is as follows: When it is recognized that the oxygen cleaning of the three-way catalytic converter is enabled after the fuel supply is resumed, according to the temperature T of the three-way catalytic converter and the critical temperature T0, determine whether to limit the oxygen cleaning rich fuel-air ratio: 1) When T<T0, the temperature of the three-way catalytic converter has not reached the critical temperature and there is no overheat risk. Rich combustion is carried out using the oxygen cleaning rich fuel-air ratio r calculated according to the current operating condition; 2) When T>T0, the temperature of the three-way catalytic converter is relatively high and there is an overheat risk. It is necessary to limit the oxygen cleaning rich fuel-air ratio r using the maximum oxygen cleaning fuel-air ratio r2 allowed by the current operating condition: when r<r2, the oxygen cleaning rich fuel-air ratio is r; when r>r2, the oxygen cleaning rich fuel-air ratio is r2; where T0<T1.

2. The three-way catalytic converter temperature and overheat protection method according to claim 1, characterized in that: The method of limiting the rich fuel-air ratio before the engine enters the fuel cut-off operating condition is as follows: 1) When a fuel cut-off request is received, determine whether the current fuel-air ratio is greater than the threshold r0. If so, set the fuel cut-off request prohibition identifier to 1, prohibit fuel cut-off, and set the fuel-air ratio of the current operating condition to the stoichiometric ratio r1 of the fuel-air ratio, and directly enter the next step; if not, set the fuel cut-off request prohibition identifier to 0 and allow fuel cut-off; 2) Determine whether the current fuel-air ratio has reached the stoichiometric ratio r1 of the fuel-air ratio. If so, set the fuel cut-off request prohibition identifier to 0 and allow fuel cut-off; if not, continue to wait until the fuel-air ratio reaches the stoichiometric ratio r1 and then allow fuel cut-off.

3. The three-way catalytic converter temperature and overheat protection method according to claim 2, characterized in that: The fuel-air ratio threshold r0 is obtained according to the three-way catalytic converter temperature MAP. The higher the temperature of the three-way catalytic converter, the closer the fuel-air ratio threshold r0 is to the stoichiometric ratio r1 of the fuel-air ratio.

4. The three-way catalytic converter temperature and overheat protection method according to claim 1, characterized in that: In Step 3, the method for the overheat protection function of the three-way catalytic converter is as follows: 1) Set the temperature limit value T1 for triggering the overheat protection of the three-way catalytic converter and the temperature limit value T2 for exiting the overheat protection, where T1>T2; 2) Determine whether the temperature of the three-way catalytic converter is greater than the temperature limit value T1. If so, set the fuel cut-off request prohibition identifier to 1, request the engine to prohibit fuel cut-off, and perform overheat protection; if not, enter the next step; 3) Determine whether the temperature of the three-way catalytic converter is less than the temperature limit T2. When the temperature of the three-way catalytic converter is less than the temperature limit T2, determine whether the prohibition of fuel cut-off request identifier of the previous sampling cycle is 1, and whether the output torque of the engine crankshaft end is less than the threshold value. If so, maintain the prohibition of fuel cut-off request; if the prohibition of fuel cut-off request identifier of the previous sampling cycle is 0, or the output torque of the engine crankshaft end is greater than the threshold value, exit the three-way catalytic converter overheating protection function, and set the prohibition of fuel cut-off request identifier to 0; when the temperature of the three-way catalytic converter is greater than the temperature limit T2, maintain the prohibition of fuel cut-off request.

5. A three-way catalytic converter temperature and overheat protection device, characterized in that: The protection device is applicable to the method described in any one of claims 1 to 4, and comprises an engine electronic control unit and a temperature sensor, a front oxygen sensor and a rear oxygen sensor electrically connected to the engine electronic control unit, wherein the temperature sensor is arranged between the three-way catalytic converter and the engine, and is used to detect the exhaust temperature of the engine; the front oxygen sensor is arranged between the three-way catalytic converter and the engine, and is used to detect the exhaust oxygen content of the engine; the rear oxygen sensor is arranged at the outlet of the three-way catalytic converter, and is used to detect the exhaust oxygen content of the three-way catalytic converter; The engine electronic control unit is used to control the temperature and overheat protection of the three-way catalytic converter according to the data detected by the temperature sensor, the front oxygen sensor and the rear oxygen sensor.

6. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein: When the processor executes the computer program, the method according to any one of claims 1 to 4 is implemented.

7. A computer-readable storage medium storing a computer program, characterized in that: When the computer program is executed by a processor, the method according to any one of claims 1 to 4 is implemented.

8. A vehicle, characterized in that: Comprising the device as claimed in claim 5.

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