Engine SCR injection module overheating protection system and control method

Abstract

The invention discloses an engine SCR injection module overheating protection system and a control method. The protection system comprises a temperature detection module, a nozzle overheating protection module, a nozzle active test module, a nozzle self-recovery module and a fault diagnosis module. The temperature detection module is used for comprehensively judging whether the temperature at the injection needle valve is in an allowable range or not according to the detected environment temperature, the detected exhaust temperature signal, the engine operation state, the exhaust gas flow and other information; the nozzle overheating protection module is used for implementing different cooling strategies according to the overtemperature range, judged by the temperature detection module, of the injection needle valve and whether the engine operates or not till the temperature, detected by the temperature detection module, of the current injection needle valve is within the allowable range. The nozzle overheating protection module is arranged and used for implementing different cooling strategies according to whether the engine operates or not, whether the nozzle is normal or not is judged through the preset repair cycle number, misjudgment is avoided, and the detection accuracy is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of engine emission control, and in particular to an engine SCR injection module overheat protection system and a control method. Background Art

[0002] At present, the SCR (Selective Catalytic Reduction, SCR for short) injection system injects urea solution into the exhaust gas to reduce NO in the exhaust gas. x Pollutants are reduced to harmless N 2 , CO 2 The injection module in the SCR injection system is usually located in the exhaust pipe. Affected by the high temperature (650°C) exhaust gas in the exhaust pipe, it is necessary to ensure that the injection module is in the normal allowable temperature range (-40°C to 120°C). If the nozzle module overheats, it will cause the SCR system to malfunction, and the emission will deteriorate, causing air pollution.

[0003] In the prior art, in order to cool the injection module, a cooling interface for the engine cooling circulating water or an air-cooled heat dissipation structure is usually provided thereon to implement passive cooling technology for the injection module. It is not possible to implement thermal management based on the actual temperature at the injection needle valve to ensure that it is within the normal allowable temperature range. At the same time, because the injection needle valve of the injection module is in the exhaust pipe, the coolant or natural wind cannot extend to the injection needle valve, and thermal management cannot be performed on it. Especially under extreme working conditions, such as sudden stopping of the vehicle after high-speed operation or shutdown and parking after DPF regeneration (diesel particulate filter) interruption, the engine cooling circulating water does not circulate or there is no natural wind, and the injection module is at great risk of overheating and damage.

[0004] Therefore, it is urgent to propose a new solution to solve the above problems. Summary of the invention

[0005] The present invention provides an engine SCR injection module overheat protection system and control method to solve the problem in the prior art that thermal management cannot be achieved according to the actual temperature at the injection needle valve to ensure that it is within a normal allowable temperature range.

[0006] The present invention provides an engine SCR injection module overheat protection system, comprising a temperature detection module, a nozzle overheat protection module, a nozzle active test module, a nozzle self-recovery module and a fault diagnosis module;

[0007] The temperature detection module is used to comprehensively determine whether the temperature at the injection needle valve is within the allowable range based on the detected ambient temperature, exhaust temperature signal, engine operation status, exhaust gas flow rate and other information;

[0008] The nozzle overheat protection module is used to implement different cooling strategies according to the over-temperature range of the injection needle valve determined by the temperature detection module and whether the engine is running, until the current temperature of the injection needle valve detected by the temperature detection module is within the allowable range;

[0009] The nozzle active test module is used to determine whether the current working state of the engine meets the active test diagnosis test access conditions, complete the active test action when the access conditions are met, calculate the actual drive waveform current curve of the nozzle during the test, and send the result to the fault diagnosis module;

[0010] The fault diagnosis module is used to determine whether the nozzle is normal by comparing whether there is a deviation between the actual driving waveform current curve of the nozzle and the theoretical driving waveform current curve;

[0011] The nozzle self-recovery module is used to perform a nozzle self-recovery action at different opening and closing frequencies according to a preset number of repair cycles when the nozzle is not working properly. After the self-recovery action is completed, the nozzle active test module is used again to perform active testing until it is finally determined whether the nozzle is normal.

[0012] Furthermore, the access conditions of the nozzle active test module include:

[0013] The engine is operating normally;

[0014] All components of the SCR system are working properly;

[0015] The urea in the urea tank and pipeline is not frozen, or the urea is heated and thawed to meet the normal urea supply conditions;

[0016] The pressure of the urea pump supply pipeline and the speed range of the internal supply pump are within the preset range.

[0017] Furthermore, the implementation of different cooling strategies according to the over-temperature range of the injection needle valve determined by the temperature detection module and whether the engine is running includes:

[0018] When the engine is running, the cooling strategy for three operating levels is determined according to the ambient temperature around the nozzle;

[0019] For the first operation level, no active protection is performed, and the engine coolant is passively cooled until the temperature at the current injection needle valve detected by the temperature detection module is within the allowable range;

[0020] For the second operation level, based on the first operation level, when there is no need for urea injection, the nozzle injection action is performed at a fixed frequency to ensure that the nozzle does not become stuck and fail at this temperature. At the same time, the nozzle injection action process will release a certain amount of urea according to the current engine exhaust flow and other parameters, thereby reducing the temperature at the injection needle valve until the current temperature at the injection needle valve detected by the temperature detection module is within the allowable range;

[0021] For the third operation level, on the basis of the second operation level, the fan operation is continued to be increased to reduce the temperature until the temperature at the current injection needle valve detected by the temperature detection module is within the allowable range.

[0022] Further, the implementation of different cooling strategies according to the over-temperature range of the injection needle valve determined by the temperature detection module and whether the engine is running also includes:

[0023] When the engine is stopped, two levels of cooling strategies are determined according to the ambient temperature around the nozzle;

[0024] For the first shutdown level, the nozzle injection action is performed at a fixed frequency to ensure that the nozzle does not become stuck and fail at this temperature. At the same time, the nozzle action process releases a fixed amount of urea to reduce the temperature at the injection needle valve until the current temperature at the injection needle valve detected by the temperature detection module is within the allowable range;

[0025] For the second shutdown level, based on the first level, the fan operation is continued to increase to cool down until the temperature at the current injection needle valve detected by the temperature detection module is within the allowable range, and then the SCR system sends a power-off request instruction to the vehicle controller.

[0026] Further, judging whether the nozzle is normal by comparing whether there is a deviation between the actual driving waveform current curve of the nozzle and the theoretical driving waveform current curve includes:

[0027] If there is no deviation between the actual driving waveform current curve of the nozzle and the preset driving waveform current curve, it is judged that the nozzle is working normally;

[0028] If there is a deviation between the actual driving waveform current curve of the nozzle and the preset driving waveform current curve, the nozzle is judged to be abnormally operating.

[0029] Furthermore, if there is a deviation between the actual driving waveform current curve of the nozzle and the preset driving waveform current curve, the nozzle is judged to be abnormally working, and the method further includes:

[0030] When it is determined that the preset number of repair cycles of the nozzle self-recovery module is greater than the preset number, it is determined that the nozzle is damaged;

[0031] When it is determined that the preset number of repair cycles of the nozzle self-recovery module is not greater than the preset number, after the repair of the self-recovery module is completed, the nozzle active test module is reused to perform active testing.

[0032] Furthermore, the opening and closing frequency is dynamically modified as the number of repair cycles increases.

[0033] The present invention also provides an engine SCR injection module overheat protection control method, comprising the following steps:

[0034] Comprehensively judge whether the temperature at the injection needle valve is within the permissible range based on the detected ambient temperature, exhaust temperature signal, engine operating status, exhaust gas flow rate and other information;

[0035] Implementing different cooling strategies according to the over-temperature range of the injection needle valve determined by the temperature detection module and whether the engine is running, until the current temperature of the injection needle valve detected by the temperature detection module is within the allowable range;

[0036] The nozzle active test module is used to determine whether the current working state of the engine meets the active test diagnosis test access conditions. When the access conditions are met, the active test action is completed, the actual drive waveform current curve of the nozzle during the test is calculated, and the result is sent to the fault diagnosis module;

[0037] The fault diagnosis module determines whether the nozzle is normal by comparing the actual driving waveform current curve of the nozzle with the theoretical driving waveform current curve to see if there is a deviation;

[0038] When the nozzle is not working properly, the nozzle self-recovery module is used to perform nozzle self-recovery actions at different opening and closing frequencies according to a preset number of repair cycles. After the self-recovery action is completed, the nozzle active test module is used again to perform active testing until it is finally determined whether the nozzle is normal.

[0039] Further, the implementation of different cooling strategies according to the over-temperature range of the injection needle valve determined by the temperature detection module and whether the engine is running includes the following steps:

[0040] When the engine is running, the cooling strategy for three operating levels is determined according to the ambient temperature around the nozzle;

[0041] For the first operation level, no active protection is performed, and the engine coolant is passively cooled until the temperature at the current injection needle valve detected by the temperature detection module is within the allowable range;

[0042] For the second operation level, based on the first operation level, when there is no need for urea injection, the nozzle injection action is performed at a fixed frequency to ensure that the nozzle does not become stuck and fail at this temperature. At the same time, the nozzle injection action process will release a certain amount of urea according to the current engine exhaust flow and other parameters, thereby reducing the temperature at the injection needle valve until the current temperature at the injection needle valve detected by the temperature detection module is within the allowable range;

[0043] For the third operation level, on the basis of the second operation level, the fan operation is continued to be increased to reduce the temperature until the temperature at the current injection needle valve detected by the temperature detection module is within the allowable range.

[0044] Further, the implementation of different cooling strategies according to the over-temperature range of the injection needle valve determined by the temperature detection module and whether the engine is running also includes the following steps:

[0045] When the engine is shut down, the cooling strategy for two shutdown levels is determined according to the ambient temperature around the nozzle;

[0046] For the first shutdown level, the nozzle injection action is performed at a fixed frequency to ensure that the nozzle does not become stuck and fail at this temperature. At the same time, the nozzle action process releases a fixed amount of urea to reduce the temperature at the injection needle valve until the current temperature at the injection needle valve detected by the temperature detection module is within the allowable range;

[0047] For the second shutdown level, based on the first shutdown level, the fan operation is continued to increase to cool down until the temperature at the current injection needle valve detected by the temperature detection module is within the allowable range, and then the SCR system sends a power-off request instruction to the vehicle controller.

[0048] Compared with the prior art, the present invention has the following beneficial effects:

[0049] 1. The engine SCR injection module overheat protection system of the present invention is provided with a nozzle overheat protection module, which is used to implement different cooling strategies according to whether the engine is running, and then uses an active test module, a fault diagnosis module and a nozzle self-recovery module to determine whether the nozzle is normal through a preset number of repair cycles, thereby avoiding the occurrence of misjudgment and improving the accuracy of detection;

[0050] 2. The engine SCR injection module overheat protection control method of the present invention can ensure that the temperature of the current injection needle valve is within the allowable range when the engine is working or not working. Even after the key is turned off, the controller still manages the power consumption and determines whether the nozzle is over-temperature through the delay relay. If it is over-temperature, the pump is still started to build pressure, the nozzle is actuated for cooling, and the fan is started for cooling until the nozzle is no longer over-temperature. Then the controller manages the power consumption of the entire vehicle, sends a power-off request, and the ECU disconnects the power of the entire vehicle. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Figure 1 It is a structural block diagram of the engine SCR injection module overheat protection control system of the present invention;

[0052] Figure 2 It is a structural schematic diagram of an engine SCR injection module overheat protection control system of the present invention;

[0053] Figure 3 The figure is a flow chart of the engine SCR injection module overheat protection control method of the present invention. DETAILED DESCRIPTION

[0054] In order to further understand the content, features and effects of the present invention, the following embodiments are given together with the attached Figures 1 to 3 The detailed instructions are as follows.

[0055] like Figure 1 As shown, this embodiment provides an engine SCR injection module overheat protection system, including a temperature detection module, a nozzle overheat protection module, a nozzle active test module, a nozzle self-recovery module and a fault diagnosis module;

[0056] The temperature detection module is used to comprehensively determine whether the temperature at the injection needle valve is within the allowable range based on the detected ambient temperature, exhaust temperature signal, engine operation status, exhaust gas flow rate and other information;

[0057] The nozzle overheat protection module is used to implement different cooling strategies according to the over-temperature range of the injection needle valve determined by the temperature detection module and whether the engine is running, until the current temperature of the injection needle valve detected by the temperature detection module is within the allowable range;

[0058] The nozzle active test module is used to determine whether the current working state of the engine meets the active test diagnosis test access conditions. When the access conditions are met, the active test action is completed, the actual drive waveform current curve of the nozzle during the test is calculated, and the result is sent to the fault diagnosis module. Each time the engine is started or there is a high temperature risk, the nozzle will be actively tested through the nozzle active test module to confirm whether the nozzle is normal;

[0059] The fault diagnosis module is used to determine whether the nozzle is normal by comparing whether there is a deviation between the actual driving waveform current curve of the nozzle and the theoretical driving waveform current curve;

[0060] The nozzle self-recovery module is used to perform self-recovery of the nozzle at different opening and closing frequencies according to a preset number of repair cycles when the nozzle is not working properly. The opening and closing frequency is dynamically corrected as the number of repair cycles increases. For example, the opening and closing frequency can be adjusted according to the deviation range from the preset drive waveform current curve. The larger the deviation range, the greater the opening and closing frequency. The opening and closing frequency here is the number of times the nozzle is opened and closed per minute. After the self-recovery action is completed, the nozzle active test module is used again to perform active testing until it is finally determined whether the nozzle is normal.

[0061] The engine SCR injection module overheat protection system of the present invention is provided with a nozzle overheat protection module, which is used to implement different cooling strategies according to whether the engine is running, and then uses an active test module, a fault diagnosis module and a nozzle self-recovery module to determine whether the nozzle is normal through a preset number of repair cycles, thereby avoiding the occurrence of misjudgment and improving the accuracy of detection.

[0062] In this embodiment, Figure 2 As shown, the whole engine SCR injection module overheat protection system includes an electronic control unit, a urea supply pump, a urea injector, a urea injection pipe, an engine coolant inlet and return pipes, a fan, an exhaust temperature sensor, an ambient temperature sensor, an exhaust connecting pipe and an exhaust gas processor, wherein the exhaust temperature sensor measures the temperature at the nozzle injection needle valve of the urea injector, and the ambient temperature sensor measures the ambient temperature, wherein the nozzle is arranged above the engine and can be cooled by a fan; the exhaust gas processor is sequentially provided with an exhaust temperature sensor and a urea injector according to the exhaust direction, the urea supply pump is connected to the liquid supply port of the urea injector through the urea injection pipe, the engine coolant inlet and return pipes are respectively connected to the cooling inlet and return ports of the urea injector, and are used to cool the urea injector, and the fan is an engine electronic cooling fan, which is arranged at the front end of the whole system.

[0063] In this embodiment, the access conditions of the nozzle active test module include:

[0064] The engine is operating normally;

[0065] All components of the SCR system are working properly;

[0066] The urea in the urea tank and pipeline is not frozen, or the urea is heated and thawed to meet the normal urea supply conditions;

[0067] The pressure of the urea pump supply pipeline and the speed range of the internal supply pump are within the preset range.

[0068] In this embodiment, different cooling strategies are implemented according to the over-temperature range at the injection needle valve determined by the temperature detection module and whether the engine is running, wherein six exhaust temperature sensors are embedded in the nozzle, and the allowable range of the temperature at the injection needle valve is set by setting different exhaust flow rates, different exhaust temperatures measured by the exhaust temperature sensors, and different engine operating parameters.

[0069] In this embodiment, when the engine is running, the cooling strategy of three operating levels is determined according to the ambient temperature around the nozzle. Here, less than 10°C is the first operating level, 10-20°C is the second operating level, and greater than 20°C is the third operating level:

[0070] For the first operation level, no active protection is performed, and the engine coolant is passively cooled until the temperature at the current injection needle valve detected by the temperature detection module is within the allowable range;

[0071] For the second operation level, based on the first operation level, when there is no need for urea injection, the nozzle injection action is performed at a fixed frequency to ensure that the nozzle does not become stuck and fail at this temperature. At the same time, the nozzle injection action process will release a certain amount of urea according to the current engine exhaust flow and other parameters, thereby reducing the temperature at the injection needle valve until the current temperature at the injection needle valve detected by the temperature detection module is within the allowable range;

[0072] For the third operation level, based on the second operation level, the fan operation is continued to be increased for cooling. At this time, the fan speed increases with the increase of ambient temperature until the temperature at the current injection needle valve detected by the temperature detection module is within the allowable range.

[0073] In this embodiment, the implementation of different cooling strategies according to the over-temperature range of the injection needle valve determined by the temperature detection module and whether the engine is running also includes:

[0074] When the engine is shut down, the cooling strategy of two shutdown levels is determined according to the ambient temperature around the nozzle. Here, less than 15℃ is the first shutdown level, and greater than 15℃ is the second shutdown level;

[0075] For the first shutdown level, the nozzle injection action is performed at a fixed frequency to ensure that the nozzle does not become stuck and fail at this temperature. At the same time, the nozzle action process releases a fixed amount of urea to reduce the temperature at the injection needle valve until the current temperature at the injection needle valve detected by the temperature detection module is within the allowable range;

[0076] For the second shutdown level, based on the first shutdown level, the fan operation is continued to increase to cool down. At this time, the fan speed increases with the increase of ambient temperature until the temperature at the current injection needle valve detected by the temperature detection module is within the allowable range, and then the SCR system sends a power-off request instruction to the vehicle controller.

[0077] In this embodiment, judging whether the nozzle is normal by comparing the actual driving waveform current curve of the nozzle with the theoretical driving waveform current curve to see whether there is a deviation includes:

[0078] If there is no deviation between the actual driving waveform current curve of the nozzle and the preset driving waveform current curve, it is judged that the nozzle is working normally;

[0079] If there is a deviation between the actual driving waveform current curve of the nozzle and the preset driving waveform current curve, the nozzle is judged to be abnormally operating.

[0080] In this embodiment, if the actual driving waveform current curve of the nozzle deviates from the preset driving waveform current curve, the nozzle is judged to be abnormally working, and the method further includes:

[0081] When it is determined that the preset number of repair cycles of the nozzle self-recovery module is greater than the preset number, it is determined that the nozzle is damaged;

[0082] When it is determined that the preset number of repair cycles of the nozzle self-recovery module is not greater than the preset number, the nozzle active test module is used again for active testing after the self-recovery module is repaired. The present invention will perform active repairs through the self-recovery module after the nozzle is abnormal. After the preset number of repair cycles, if the nozzle active test module still cannot confirm that the nozzle is working normally, a nozzle failure will be reported. After the nozzle self-recovery module repairs it, and then the nozzle active test module confirms that the nozzle is working normally, the nozzle continues to work normally, solving the problem of false alarms of the nozzle under complex working conditions.

[0083] In this embodiment, Figure 3 As shown, the present invention also provides an engine SCR injection module overheat protection control method, comprising the following steps:

[0084] S1. Comprehensively determine whether the temperature at the injection needle valve is within the permissible range based on the detected ambient temperature, exhaust temperature signal, engine operation status, exhaust gas flow rate and other information;

[0085] S2, implementing different cooling strategies according to the over-temperature range of the injection needle valve determined by the temperature detection module and whether the engine is running, until the current temperature of the injection needle valve detected by the temperature detection module is within the allowable range;

[0086] S3, judging whether the current working state of the engine meets the active test diagnosis test access conditions through the nozzle active test module, completing the active test action when the access conditions are met, calculating the actual drive waveform current curve of the nozzle during the test, and sending the result to the fault diagnosis module;

[0087] S4, the fault diagnosis module determines whether the nozzle is normal by comparing the actual driving waveform current curve of the nozzle with the theoretical driving waveform current curve to see whether there is a deviation;

[0088] S5. When the nozzle is not working properly, the nozzle self-recovery module is used to perform the nozzle self-recovery action at different opening and closing frequencies according to the preset number of repair cycles. After the self-recovery action is completed, the nozzle active test module is used again to perform active testing until it is finally determined whether the nozzle is normal.

[0089] The engine SCR injection module overheat protection control method of the present invention can ensure that the temperature of the current injection needle valve is within the allowable range when the engine is working or not working. Even after the key is turned off, the controller still manages the power consumption and determines whether the nozzle is over-temperature through the delay relay. If it is over-temperature, the pump is still started to build pressure, the nozzle is actuated for cooling, and the fan is started for cooling until the nozzle is no longer over-temperature. Then the controller manages the power consumption of the entire vehicle, sends a power-off request, and the ECU disconnects the power of the entire vehicle.

[0090] In this embodiment, the implementation of different cooling strategies according to the over-temperature range of the injection needle valve determined by the temperature detection module and whether the engine is running includes the following steps:

[0091] When the engine is running, the cooling strategy for three operating levels is determined according to the ambient temperature around the nozzle;

[0092] For the first operation level, no active protection is performed, and the engine coolant is passively cooled until the temperature at the current injection needle valve detected by the temperature detection module is within the allowable range;

[0093] For the second operation level, based on the first operation level, when there is no need for urea injection, the nozzle injection action is performed at a fixed frequency to ensure that the nozzle does not become stuck and fail at this temperature. At the same time, the nozzle injection action process will release a certain amount of urea according to the current engine exhaust flow and other parameters, thereby reducing the temperature at the injection needle valve until the current temperature at the injection needle valve detected by the temperature detection module is within the allowable range;

[0094] For the third operation level, on the basis of the second operation level, the fan operation is continued to be increased to reduce the temperature until the temperature at the current injection needle valve detected by the temperature detection module is within the allowable range.

[0095] In this embodiment, the implementation of different cooling strategies according to the over-temperature range at the injection needle valve determined by the temperature detection module and whether the engine is running also includes the following steps:

[0096] When the engine is shut down, the cooling strategy for two shutdown levels is determined according to the ambient temperature around the nozzle;

[0097] For the first shutdown level, the nozzle injection action is performed at a fixed frequency to ensure that the nozzle does not become stuck and fail at this temperature. At the same time, the nozzle action process releases a fixed amount of urea to reduce the temperature at the injection needle valve until the current temperature at the injection needle valve detected by the temperature detection module is within the allowable range;

[0098] For the second shutdown level, based on the first shutdown level, the fan operation is continued to increase to cool down until the temperature at the current injection needle valve detected by the temperature detection module is within the allowable range, and then the SCR system sends a power-off request instruction to the vehicle controller.

[0099] The invention described above only expresses the implementation methods of the embodiments of the present invention, and cannot be understood as limiting the scope of the invention patent, nor does it impose any form of limitation on the structure of the embodiments of the present invention. It should be pointed out that for ordinary technicians in this field, several changes and improvements can be made without departing from the concept of the embodiments of the present invention, which all belong to the protection scope of the embodiments of the present invention.

Claims

1. An engine SCR injection module overheat protection system, characterized in that: It includes a temperature detection module, a nozzle overheat protection module, a nozzle active test module, a nozzle self-recovery module and a fault diagnosis module; The temperature detection module is used to comprehensively determine whether the temperature at the injection needle valve is within the allowable range based on the detected ambient temperature, exhaust temperature signal, engine operation status, exhaust gas flow rate and other information; The nozzle overheat protection module is used to implement different cooling strategies according to the over-temperature range of the injection needle valve determined by the temperature detection module and whether the engine is running, until the current temperature of the injection needle valve detected by the temperature detection module is within the allowable range; The nozzle active test module is used to determine whether the current working state of the engine meets the active test diagnosis test access conditions, complete the active test action when the access conditions are met, calculate the actual drive waveform current curve of the nozzle during the test, and send the result to the fault diagnosis module; The fault diagnosis module is used to determine whether the nozzle is normal by comparing whether there is a deviation between the actual driving waveform current curve of the nozzle and the theoretical driving waveform current curve; The nozzle self-recovery module is used to perform a nozzle self-recovery action at different opening and closing frequencies according to a preset number of repair cycles when the nozzle is not working properly. After the self-recovery action is completed, the nozzle active test module is used again to perform active testing until it is finally determined whether the nozzle is normal.

2. An engine SCR injection module overheat protection system according to claim 1, characterized in that: The access conditions of the nozzle active test module include: The engine is operating normally; All components of the SCR system are working properly; The urea in the urea tank and pipeline is not frozen, or the urea is heated and thawed to meet the normal urea supply conditions; The pressure of the urea pump supply pipeline and the speed range of the internal supply pump are within the preset range.

3. The engine SCR injection module overheat protection system according to claim 1, characterized in that: The implementation of different cooling strategies according to the over-temperature range of the injection needle valve determined by the temperature detection module and whether the engine is running includes: When the engine is running, the cooling strategy for three operating levels is determined according to the ambient temperature around the nozzle; For the first operation level, no active protection is performed, and the engine coolant is passively cooled until the temperature at the current injection needle valve detected by the temperature detection module is within the allowable range; For the second operation level, based on the first operation level, when there is no need for urea injection, the nozzle injection action is performed at a fixed frequency to ensure that the nozzle does not become stuck and fail at this temperature. At the same time, the nozzle injection action process will release a certain amount of urea according to the current engine exhaust flow and other parameters, thereby reducing the temperature at the injection needle valve until the current temperature at the injection needle valve detected by the temperature detection module is within the allowable range; For the third operation level, on the basis of the second operation level, the fan operation is continued to be increased to reduce the temperature until the temperature at the current injection needle valve detected by the temperature detection module is within the allowable range.

4. An engine SCR injection module overheat protection system according to claim 3, characterized in that: The implementation of different cooling strategies according to the over-temperature range of the injection needle valve determined by the temperature detection module and whether the engine is running also includes: When the engine is shut down, the cooling strategy for two shutdown levels is determined according to the ambient temperature around the nozzle; For the first shutdown level, the nozzle injection action is performed at a fixed frequency to ensure that the nozzle does not become stuck and fail at this temperature. At the same time, the nozzle action process releases a fixed amount of urea to reduce the temperature at the injection needle valve until the current temperature at the injection needle valve detected by the temperature detection module is within the allowable range; For the second shutdown level, based on the first shutdown level, the fan operation is continued to increase to cool down until the temperature at the current injection needle valve detected by the temperature detection module is within the allowable range, and then the SCR system sends a power-off request instruction to the vehicle controller.

5. The engine SCR injection module overheat protection system according to claim 1, characterized in that: The step of comparing the actual driving waveform current curve of the nozzle with the theoretical driving waveform current curve to determine whether the nozzle is normal includes: If there is no deviation between the actual driving waveform current curve of the nozzle and the preset driving waveform current curve, it is judged that the nozzle is working normally; If there is a deviation between the actual driving waveform current curve of the nozzle and the preset driving waveform current curve, the nozzle is judged to be abnormally operating.

6. An engine SCR injection module overheat protection system according to claim 5, characterized in that: If the actual driving waveform current curve of the nozzle deviates from the preset driving waveform current curve, the nozzle is judged to be abnormally working, further comprising: When it is determined that the preset number of repair cycles of the nozzle self-recovery module is greater than the preset number, it is determined that the nozzle is damaged; When it is determined that the preset number of repair cycles of the nozzle self-recovery module is not greater than the preset number, after the repair of the self-recovery module is completed, the nozzle active test module is reused to perform active testing.

7. An engine SCR injection module overheat protection system according to claim 1, characterized in that: The opening and closing frequency is dynamically modified as the number of repair cycles increases.

8. An engine SCR injection module overheat protection control method, characterized in that: The following steps are involved: Comprehensively judge whether the temperature at the injection needle valve is within the permissible range based on the detected ambient temperature, exhaust temperature signal, engine operating status, exhaust gas flow rate and other information; Implementing different cooling strategies according to the over-temperature range of the injection needle valve determined by the temperature detection module and whether the engine is running, until the current temperature of the injection needle valve detected by the temperature detection module is within the allowable range; The nozzle active test module is used to determine whether the current working state of the engine meets the active test diagnosis test access conditions. When the access conditions are met, the active test action is completed, the actual drive waveform current curve of the nozzle during the test is calculated, and the result is sent to the fault diagnosis module; The fault diagnosis module determines whether the nozzle is normal by comparing the actual driving waveform current curve of the nozzle with the theoretical driving waveform current curve to see if there is a deviation; When the nozzle is not working properly, the nozzle self-recovery module is used to perform nozzle self-recovery actions at different opening and closing frequencies according to a preset number of repair cycles. After the self-recovery action is completed, the nozzle active test module is used again to perform active testing until it is finally determined whether the nozzle is normal.

9. The engine SCR injection module overheat protection control method according to claim 8, characterized in that: The implementation of different cooling strategies according to the over-temperature range of the injection needle valve determined by the temperature detection module and whether the engine is running includes the following steps: When the engine is running, the cooling strategy for three operating levels is determined according to the ambient temperature around the nozzle; For the first operation level, no active protection is performed, and the engine coolant is passively cooled until the temperature at the current injection needle valve detected by the temperature detection module is within the allowable range; For the second operation level, based on the first operation level, when there is no need for urea injection, the nozzle injection action is performed at a fixed frequency to ensure that the nozzle does not become stuck and fail at this temperature. At the same time, the nozzle injection action process will release a certain amount of urea according to the current engine exhaust flow and other parameters, thereby reducing the temperature at the injection needle valve until the current temperature at the injection needle valve detected by the temperature detection module is within the allowable range; For the third operation level, on the basis of the second operation level, the fan operation is continued to be increased to reduce the temperature until the temperature at the current injection needle valve detected by the temperature detection module is within the allowable range.

10. The engine SCR injection module overheat protection control method according to claim 8, characterized in that: The implementation of different cooling strategies according to the over-temperature range of the injection needle valve determined by the temperature detection module and whether the engine is running also includes the following steps: When the engine is shut down, the cooling strategy for two shutdown levels is determined according to the ambient temperature around the nozzle; For the first shutdown level, the nozzle injection action is performed at a fixed frequency to ensure that the nozzle does not become stuck and fail at this temperature. At the same time, the nozzle action process releases a fixed amount of urea to reduce the temperature at the injection needle valve until the current temperature at the injection needle valve detected by the temperature detection module is within the allowable range; For the second shutdown level, based on the first shutdown level, the fan operation is continued to increase to cool down until the temperature at the current injection needle valve detected by the temperature detection module is within the allowable range, and then the SCR system sends a power-off request instruction to the vehicle controller.

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