An engine SCR injection module overheat protection system and control method

Abstract

This invention discloses an overheat protection system and control method for an engine SCR injection module. The protection system includes a temperature detection module, a nozzle overheat protection module, a nozzle active testing 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 detected ambient temperature, exhaust temperature signals, engine operating status, exhaust gas flow, and other information. The nozzle overheat protection module is used to implement different cooling strategies based on the overheat range determined by the temperature detection module at the injection needle valve and whether the engine is running, until the current temperature at the injection needle valve, as detected by the temperature detection module, is within the allowable range. This invention, by setting up a nozzle overheat protection module, implements different cooling strategies based on whether the engine is running, and determines whether the nozzle is functioning correctly through a preset number of repair cycles, avoiding misjudgments and improving detection accuracy.

Description

Technical Field

[0001] This invention relates to the field of engine emission control technology, specifically to an engine SCR injection module overheat protection system and control method. Background Technology

[0002] Currently, SCR (Selective Catalytic Reduction) injection systems remove NO from the exhaust gas by injecting urea solution into the exhaust gas. x Pollutants are reduced to harmless N2, CO2, and water. The injection module in the SCR injection system is usually located in the exhaust pipe. Affected by the high temperature (650℃) of the exhaust gas, the injection module must be kept within the normal allowable temperature range (-40℃~120℃). If the nozzle module overheats, it will cause the SCR system to malfunction, and the emissions will worsen, causing air pollution.

[0003] In existing technologies, to cool the injection module, it is typically equipped with a cooling interface for engine cooling water or an air-cooled heat dissipation structure, achieving passive cooling technology for the injection module. This cannot achieve thermal management based on the actual temperature at the injection needle valve, ensuring it remains within the normal allowable temperature range. Furthermore, because the injection needle valve of the injection module is located in the exhaust pipe, coolant or natural air cannot reach it, making thermal management impossible. Especially under extreme conditions, such as sudden stopping after high-speed vehicle operation or engine shutdown after DPF regeneration (diesel particulate filter) interruption, where engine cooling water circulation is interrupted or there is no natural airflow, the injection module faces a significant risk of overheating and damage.

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

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

[0006] This invention provides an overheat protection system for an engine SCR injection module, including a temperature detection module, a nozzle overheat protection module, a nozzle active testing 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 operating status, exhaust gas flow, and other information.

[0008] The nozzle overheat protection module is used to implement different cooling strategies based on the overheat range at the injection needle valve determined by the temperature detection module and whether the engine is running, until the current temperature at 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 diagnostic 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.

[0010] The fault diagnosis module is used to determine whether the nozzle is normal by comparing the actual drive waveform current curve and the theoretical drive waveform current curve of the nozzle to see if there is a deviation.

[0011] The nozzle self-recovery module is used to perform the 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 to perform active testing again until it is finally determined whether the nozzle is normal.

[0012] Furthermore, the admission criteria for the active nozzle testing module include:

[0013] The engine is running normally;

[0014] All components of the SCR system are functioning normally;

[0015] The urea in the urea tank and pipeline is not frozen, or if it is frozen, it has been thawed by heating and has reached the normal urea supply condition.

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

[0017] Furthermore, the implementation of different cooling strategies based on the overheat range at the injection needle valve determined by the temperature detection module and whether the engine is running includes:

[0018] When the engine is running, cooling strategies for three operating levels are determined based on the ambient temperature around the nozzle.

[0019] For the first operating level, no active protection is provided; instead, passive cooling is achieved through engine coolant until the temperature at the injection needle valve, as detected by the temperature detection module, is within the permissible range.

[0020] For the second operating level, based on the first operating 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 jam or fail at this temperature. At the same time, during the nozzle injection action, a certain amount of urea will be released 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 operating level, based on the second operating level, the fan operation is increased to cool down until the temperature at the injection needle valve detected by the temperature detection module is within the allowable range.

[0022] Furthermore, the method of implementing different cooling strategies based on the overheat range at the injection needle valve determined by the temperature detection module and whether the engine is running also includes:

[0023] When the engine stops, two levels of cooling strategies are determined based on the ambient temperature around the nozzles;

[0024] For the first shutdown level, the nozzle spraying action is performed at a fixed frequency to ensure that the nozzle does not jam or fail at this temperature. At the same time, a fixed amount of urea is released during the nozzle action to reduce the temperature at the injection needle valve until the 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 increased to cool down until the temperature at the injection needle valve detected by the temperature detection module is within the allowable range. Then, the SCR system sends a power-off request command to the vehicle controller.

[0026] Furthermore, the step of determining whether the nozzle is functioning correctly by comparing the actual drive waveform current curve and the theoretical drive waveform current curve of the nozzle includes:

[0027] If the actual drive waveform current curve of the nozzle does not deviate from the preset drive waveform current curve, then the nozzle is judged to be working normally.

[0028] If the actual drive waveform current curve of the nozzle deviates from the preset drive waveform current curve, the nozzle is determined to be malfunctioning.

[0029] Furthermore, if there is a deviation between the actual drive waveform current curve of the nozzle and the preset drive waveform current curve, the nozzle is determined to be malfunctioning. This also includes:

[0030] If the preset number of repair cycles for the nozzle self-recovery module is greater than the preset number, the nozzle is determined to be damaged.

[0031] If it is determined that the preset number of repair cycles of the nozzle self-recovery module is not greater than the preset number, then after the self-recovery module has completed its repair, the nozzle active test module will be used again for active testing.

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

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

[0034] Based on the detected ambient temperature, exhaust temperature signal, engine operating status, exhaust gas flow rate and other information, we can comprehensively determine whether the temperature at the injection needle valve is within the allowable range.

[0035] Different cooling strategies are implemented based on the over-temperature range at the injection needle valve determined by the temperature detection module and whether the engine is running, until the current temperature at the injection needle valve detected by the temperature detection module is within the allowable range.

[0036] The active nozzle test module determines whether the current operating state of the engine meets the active test diagnostic 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 functioning properly by comparing the actual drive waveform current curve and the theoretical drive waveform current curve of the nozzle to see if there is a deviation.

[0038] When the nozzle malfunctions, the nozzle self-recovery module performs a self-recovery action 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 to perform an active test again until it is finally determined whether the nozzle is normal.

[0039] Furthermore, the implementation of different cooling strategies based on the overheat range at 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, cooling strategies for three operating levels are determined based on the ambient temperature around the nozzle.

[0041] For the first operating level, no active protection is provided; instead, passive cooling is achieved through engine coolant until the temperature at the injection needle valve, as detected by the temperature detection module, is within the permissible range.

[0042] For the second operating level, based on the first operating 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 jam or fail at this temperature. At the same time, during the nozzle injection action, a certain amount of urea will be released 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 operating level, based on the second operating level, the fan operation is increased to cool down until the temperature at the injection needle valve detected by the temperature detection module is within the allowable range.

[0044] Furthermore, the implementation of different cooling strategies based on the overheat range at 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 stops, cooling strategies for two shutdown levels are determined based on the ambient temperature around the nozzle.

[0046] For the first shutdown level, the nozzle spraying action is performed at a fixed frequency to ensure that the nozzle does not jam or fail at this temperature. At the same time, a fixed amount of urea is released during the nozzle action to reduce the temperature at the injection needle valve until the 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 increased to cool down until the temperature at the injection needle valve detected by the temperature detection module is within the allowable range. Then, the SCR system sends a power-off request command to the vehicle controller.

[0048] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0049] 1. The engine SCR injection module overheat protection system of the present invention sets up a nozzle overheat protection module, which is used to implement different cooling strategies according to whether the engine is running. Then, by using an active testing module, a fault diagnosis module and a nozzle self-recovery module, the system determines whether the nozzle is normal by a preset number of repair cycles, thereby avoiding 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 at the injection needle valve is within the allowable range when the engine is running and when the engine is not running. Even after the power is turned off and the key is turned on, the controller still manages the power supply. It uses a time-delay relay to determine whether the nozzle is overheating. If the temperature is overheating, it will start the pump to build up pressure, the nozzle to operate to cool, and the fan to run to cool until the nozzle is no longer overheating. Then the controller will manage the power supply of the whole vehicle and send a power-off request. The ECU disconnects the power to the whole vehicle. Attached Figure Description

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

[0052] Figure 2 This is a schematic diagram of the overheat protection control system for the engine SCR injection module of the present invention.

[0053] Figure 3 This is a flowchart of the engine SCR injection module overheat protection control method of the present invention. Detailed Implementation

[0054] To further understand the invention's content, features, and effects, the following embodiments are provided, along with accompanying drawings. Figures 1-3 The details 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 testing 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 operating status, exhaust gas flow, and other information.

[0057] The nozzle overheat protection module is used to implement different cooling strategies based on the overheat range at the injection needle valve determined by the temperature detection module and whether the engine is running, until the current temperature at 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 diagnostic 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. Every time the engine is started or there is a risk of high temperature, 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 the actual drive waveform current curve and the theoretical drive waveform current curve of the nozzle to see if there is a deviation.

[0060] The nozzle self-recovery module is used to perform self-recovery actions on 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, it can be adjusted according to the deviation range from the preset drive waveform current curve. The larger the deviation range, the larger the opening and closing frequency. The opening and closing frequency is the number of times the nozzle opens and closes 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 sets up a nozzle overheat protection module, which implements different cooling strategies according to whether the engine is running. Then, by using an active testing module, a fault diagnosis module and a nozzle self-recovery module, the system determines whether the nozzle is normal by a preset number of repair cycles, thereby avoiding misjudgment and improving the accuracy of detection.

[0062] In this embodiment, as Figure 2 As shown, the entire engine SCR injection module overheat protection system includes an electronic control unit, a urea supply pump, a urea injector, a urea injection pipe, engine coolant inlet and outlet pipes, a fan, an exhaust temperature sensor, an ambient temperature sensor, an exhaust connection pipe, and an exhaust gas processor. 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. The nozzle is located above the engine and can be cooled by the fan. The exhaust gas processor is arranged with the exhaust temperature sensor and the urea injector in sequence according to the exhaust direction. The urea supply pump is connected to the supply port of the urea injector through the urea injection pipe. The engine coolant inlet and outlet pipes are connected to the cooling inlet and outlet of the urea injector, respectively, to cool the urea injector. The fan is an engine electronic cooling fan, which is located at the front end of the entire system.

[0063] In this embodiment, the admission criteria for the active nozzle testing module include:

[0064] The engine is running normally;

[0065] All components of the SCR system are functioning normally;

[0066] The urea in the urea tank and pipeline is not frozen, or if it is frozen, it has been thawed by heating and has reached the normal urea supply condition.

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

[0068] In this embodiment, different cooling strategies are implemented based on the overheat range at the injection needle valve determined by the temperature detection module and whether the engine is running. Six exhaust temperature sensors are pre-embedded in the nozzle. By setting different exhaust flow rates, different exhaust temperatures measured by the exhaust temperature sensors, and different engine operating parameters, the allowable temperature range at the injection needle valve is set.

[0069] In this embodiment, when the engine is running, a cooling strategy of three operating levels is determined based on 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 operating level, no active protection is provided; instead, passive cooling is achieved through engine coolant until the temperature at the injection needle valve, as detected by the temperature detection module, is within the permissible range.

[0071] For the second operating level, based on the first operating 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 jam or fail at this temperature. At the same time, during the nozzle injection action, a certain amount of urea will be released 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 operating level, based on the second operating level, the fan operation is further increased 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.

[0073] In this embodiment, the implementation of different cooling strategies based on the overheat range at the injection needle valve determined by the temperature detection module and whether the engine is running also includes:

[0074] When the engine stops, the cooling strategy for two shutdown levels is determined based on the ambient temperature around the nozzle. The first shutdown level is when the temperature is less than 15°C, and the second shutdown level is when the temperature is greater than 15°C.

[0075] For the first shutdown level, the nozzle spraying action is performed at a fixed frequency to ensure that the nozzle does not jam or fail at this temperature. At the same time, a fixed amount of urea is released during the nozzle action to reduce the temperature at the injection needle valve until the 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 further increased to cool the system. At this time, the fan speed increases with the increase of ambient temperature until the temperature at the injection needle valve detected by the temperature detection module is within the allowable range. Then, the SCR system sends a power-off request command to the vehicle controller.

[0077] In this embodiment, determining whether the nozzle is functioning correctly by comparing the actual drive waveform current curve and the theoretical drive waveform current curve of the nozzle includes:

[0078] If the actual drive waveform current curve of the nozzle does not deviate from the preset drive waveform current curve, then the nozzle is judged to be working normally.

[0079] If the actual drive waveform current curve of the nozzle deviates from the preset drive waveform current curve, the nozzle is determined to be malfunctioning.

[0080] In this embodiment, if there is a deviation between the actual drive waveform current curve of the nozzle and the preset drive waveform current curve, the nozzle is determined to be malfunctioning. The method further includes:

[0081] If the preset number of repair cycles for the nozzle self-recovery module is greater than the preset number, the nozzle is determined to be damaged.

[0082] If the preset number of repair cycles for the nozzle self-recovery module is determined to be no greater than a preset number, then after the self-recovery module completes its repair, the nozzle active testing module is used again for active testing. This invention, when a nozzle malfunctions, will actively repair it via the self-recovery module. If, after the preset number of repair cycles, the nozzle active testing module still cannot confirm normal operation, a nozzle fault is reported. After repair by the nozzle self-recovery module and confirmation of normal operation by the nozzle active testing module, the nozzle continues to work normally, thus solving the problem of false nozzle alarms under complex operating conditions.

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

[0084] S1. Based on the detected ambient temperature, exhaust temperature signal, engine operating status, exhaust gas flow rate and other information, determine whether the temperature at the injection needle valve is within the allowable range.

[0085] S2. Implement different cooling strategies based on the over-temperature range at the injection needle valve determined by the temperature detection module and whether the engine is running, until the current temperature at the injection needle valve detected by the temperature detection module is within the allowable range.

[0086] S3. The active test module of the nozzle is used to determine whether the current working state of the engine meets the active test diagnostic 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.

[0087] S4. The fault diagnosis module determines whether the nozzle is normal by comparing the actual drive waveform current curve and the theoretical drive waveform current curve of the nozzle to see if there is a deviation.

[0088] S5. When the nozzle is not working properly, the nozzle self-recovery module performs the self-recovery action of the nozzle 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 at the injection needle valve is within the allowable range when the engine is running and when the engine is not running. Even after the power is turned off and the key is turned on, the controller still manages the power supply. It uses a time-delay relay to determine whether the nozzle is overheating. If the temperature is overheating, it will start the pump to build up pressure, the nozzle to operate to cool, and the fan to run to cool until the nozzle is no longer overheating. Then the controller will manage the power supply of the whole vehicle and send a power-off request. The ECU disconnects the power to the whole vehicle.

[0090] In this embodiment, the implementation of different cooling strategies based on the overheat range at 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, cooling strategies for three operating levels are determined based on the ambient temperature around the nozzle.

[0092] For the first operating level, no active protection is provided; instead, passive cooling is achieved through engine coolant until the temperature at the injection needle valve, as detected by the temperature detection module, is within the permissible range.

[0093] For the second operating level, based on the first operating 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 jam or fail at this temperature. At the same time, during the nozzle injection action, a certain amount of urea will be released 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 operating level, based on the second operating level, the fan operation is increased to cool down until the temperature at the injection needle valve detected by the temperature detection module is within the allowable range.

[0095] In this embodiment, the implementation of different cooling strategies based on the overheat 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 stops, cooling strategies for two shutdown levels are determined based on the ambient temperature around the nozzle.

[0097] For the first shutdown level, the nozzle spraying action is performed at a fixed frequency to ensure that the nozzle does not jam or fail at this temperature. At the same time, a fixed amount of urea is released during the nozzle action to reduce the temperature at the injection needle valve until the 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 increased to cool down until the temperature at the injection needle valve detected by the temperature detection module is within the allowable range. Then, the SCR system sends a power-off request command to the vehicle controller.

[0099] The above-described invention merely illustrates implementation methods of the present invention and should not be construed as limiting the scope of the invention patent, nor as imposing any form of limitation on the structure of the embodiments of the present invention. It should be noted that those skilled in the art can make various changes and improvements without departing from the concept of the embodiments of the present invention, and these all fall within the protection scope of the embodiments of the present invention.

Claims

1. An overheat protection system for an engine SCR injection module, characterized in that: It includes a temperature detection module, a nozzle overheat protection module, a nozzle active testing 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 operating status, exhaust gas flow, and other information. The nozzle overheat protection module is used to implement different cooling strategies based on the overheat range at the injection needle valve determined by the temperature detection module and whether the engine is running, until the current temperature at 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 diagnostic 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 is used to determine whether the nozzle is normal by comparing the actual drive waveform current curve and the theoretical drive waveform current curve of the nozzle to see if there is a deviation. The nozzle self-recovery module is used to perform the 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 to perform active testing again until it is finally determined whether the nozzle is normal.

2. The engine SCR injection module overheat protection system according to claim 1, characterized in that, The admission criteria for the active nozzle testing module include: The engine is running normally; All components of the SCR system are functioning normally; The urea in the urea tank and pipeline is not frozen, or if it is frozen, it has been thawed by heating and has reached the normal urea supply condition. The pressure of the urea pump's supply line 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 different cooling strategies implemented based on the overheat range at the injection needle valve determined by the temperature detection module and whether the engine is running include: When the engine is running, cooling strategies for three operating levels are determined based on the ambient temperature around the nozzle. For the first operating level, no active protection is provided; instead, passive cooling is achieved through engine coolant until the temperature at the injection needle valve, as detected by the temperature detection module, is within the permissible range. For the second operating level, based on the first operating 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 jam or fail at this temperature. At the same time, during the nozzle injection action, a certain amount of urea will be released 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 operating level, based on the second operating level, the fan operation is increased to cool down until the temperature at the injection needle valve detected by the temperature detection module is within the allowable range.

4. The engine SCR injection module overheat protection system according to claim 3, characterized in that, The method of implementing different cooling strategies based on the overheat range at the injection needle valve determined by the temperature detection module and whether the engine is running also includes: When the engine stops, cooling strategies for two shutdown levels are determined based on the ambient temperature around the nozzle. For the first shutdown level, the nozzle spraying action is performed at a fixed frequency to ensure that the nozzle does not jam or fail at this temperature. At the same time, a fixed amount of urea is released during the nozzle action to reduce the temperature at the injection needle valve until the 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 increased to cool down until the temperature at the injection needle valve detected by the temperature detection module is within the allowable range. Then, the SCR system sends a power-off request command to the vehicle controller.

5. The engine SCR injection module overheat protection system according to claim 1, characterized in that, The method of determining whether the nozzle is functioning properly by comparing the actual drive waveform current curve and the theoretical drive waveform current curve of the nozzle includes: If the actual drive waveform current curve of the nozzle does not deviate from the preset drive waveform current curve, then the nozzle is judged to be working normally. If the actual drive waveform current curve of the nozzle deviates from the preset drive waveform current curve, the nozzle is determined to be malfunctioning.

6. The engine SCR injection module overheat protection system according to claim 5, characterized in that, If the actual drive waveform current curve of the nozzle deviates from the preset drive waveform current curve, the nozzle is determined to be malfunctioning. This also includes: If the preset number of repair cycles for the nozzle self-recovery module is greater than the preset number, the nozzle is determined to be damaged. If it is determined that the preset number of repair cycles of the nozzle self-recovery module is not greater than the preset number, then after the self-recovery module has completed its repair, the nozzle active test module will be used again for active testing.

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

8. A method for overheat protection control of an engine SCR injection module, characterized in that, Includes the following steps: Based on the detected ambient temperature, exhaust temperature signal, engine operating status, exhaust gas flow rate and other information, we can comprehensively determine whether the temperature at the injection needle valve is within the allowable range. Different cooling strategies are implemented based on the over-temperature range at the injection needle valve determined by the temperature detection module and whether the engine is running, until the current temperature at the injection needle valve detected by the temperature detection module is within the allowable range. The active nozzle test module determines whether the current operating state of the engine meets the active test diagnostic 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 functioning properly by comparing the actual drive waveform current curve and the theoretical drive waveform current curve of the nozzle to see if there is a deviation. When the nozzle malfunctions, the nozzle self-recovery module performs a self-recovery action 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 to perform an active test again until it is finally determined whether the nozzle is normal.

9. The overheat protection control method for an engine SCR injection module according to claim 8, characterized in that, The different cooling strategies implemented based on the overheat range at the injection needle valve determined by the temperature detection module and whether the engine is running include the following steps: When the engine is running, cooling strategies for three operating levels are determined based on the ambient temperature around the nozzle. For the first operating level, no active protection is provided; instead, passive cooling is achieved through engine coolant until the temperature at the injection needle valve, as detected by the temperature detection module, is within the permissible range. For the second operating level, based on the first operating 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 jam or fail at this temperature. At the same time, during the nozzle injection action, a certain amount of urea will be released 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 operating level, based on the second operating level, the fan operation is increased to cool down until the temperature at the injection needle valve detected by the temperature detection module is within the allowable range.

10. The overheat protection control method for an engine SCR injection module according to claim 8, characterized in that, The method of implementing different cooling strategies based on the overheat range at the injection needle valve determined by the temperature detection module and whether the engine is running also includes the following steps: When the engine stops, cooling strategies for two shutdown levels are determined based on the ambient temperature around the nozzle. For the first shutdown level, the nozzle spraying action is performed at a fixed frequency to ensure that the nozzle does not jam or fail at this temperature. At the same time, a fixed amount of urea is released during the nozzle action to reduce the temperature at the injection needle valve until the 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 increased to cool down until the temperature at the injection needle valve detected by the temperature detection module is within the allowable range. Then, the SCR system sends a power-off request command to the vehicle controller.

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