Heating and unfreezing control method and system for SCR (Selective Catalytic Reduction) system

Abstract

The invention discloses an SCR system heating unfreezing control method and system, and the method comprises the steps: starting and continuously carrying out the heating unfreezing of a urea pump and a urea pipe when the SCR system meets a preset heating unfreezing condition; meanwhile, in the engine driving mode, the urea box is directly heated and unfrozen through engine cooling liquid; in the pure electric driving mode, when the temperature of engine cooling liquid is larger than the first preset cooling liquid temperature, an electronic water pump is started to circulate the engine cooling liquid to heat and unfreeze the urea box; otherwise, switching to an engine driving mode for heating and unfreezing; during heating unfreezing, the SCR system is subjected to pressure buildup under the pressure buildup condition, and heating unfreezing is stopped when pressure buildup succeeds. The SCR system heating and unfreezing control method of the hybrid power vehicle under different driving modes is comprehensively considered, and the reliability of the SCR system heating and unfreezing control technology of the hybrid power vehicle is effectively improved.

Description

Technical Field

[0001] The present application relates to the technical field of SCR systems, and particularly to a method and system for controlling the heating and thawing of an SCR system. Background Art

[0002] Hybrid vehicles have become a hot topic of concern for automakers because they can meet both fuel consumption standards and obtain new energy credits. These vehicles are usually equipped with diesel engines, and their exhaust gas treatment relies on an SCR (Selective Catalytic Reduction) system to reduce emissions. Given China's vast territory and diverse climate conditions, especially in cold regions in the north, the SCR system must be able to adapt to low-temperature environments. To meet the requirements of the reactant low-temperature performance in Clause G.2.3 of the national standard GB17691-2018, the SCR system needs to have the function of heating and thawing to ensure normal operation under low-temperature conditions. Therefore, the development and application of SCR system heating and thawing technologies that can operate stably under extreme climate conditions are of great significance for meeting regulatory requirements and ensuring vehicle performance.

[0003] Existing SCR system heating and thawing control technologies are mainly used for traditional fuel vehicles, and the applicability to hybrid vehicles has not been fully considered, resulting in poor reliability of the SCR system heating and thawing technology in hybrid vehicles. Summary of the Invention

[0004] The present application provides a method and system for controlling the heating and thawing of an SCR system, which can solve the technical problem of poor reliability of the current SCR system heating and thawing control technology in hybrid vehicles.

[0005] To achieve the above object, in a first aspect, the present application provides a method for controlling the heating and thawing of an SCR system, the method comprising:

[0006] When the SCR system meets the preset heating and thawing conditions, start and continuously heat and thaw the urea pump and urea pipe. At the same time, in the engine drive mode, directly heat and thaw the urea tank through the engine coolant.

[0007] In the pure electric drive mode, when the engine coolant temperature is greater than the first preset coolant temperature, start the electronic water pump to circulate the engine coolant to heat and thaw the urea tank; otherwise, switch to the engine drive mode for heating and thawing.

[0008] During heating and thawing, the SCR system builds pressure under pressure-building conditions, and stops heating and thawing when the pressure building is successful.

[0009] Further, in an embodiment, the preset heating and thawing conditions are:

[0010] The temperature of the urea tank is less than the first preset heating and thawing temperature, and the engine coolant temperature is greater than the second preset heating and thawing temperature, the ambient temperature is less than the first preset heating and thawing temperature, or the temperature of the urea pump is less than the first preset heating and thawing temperature.

[0011] Further, in one embodiment, before determining that the SCR system meets the preset heating and thawing conditions, it further includes:

[0012] The SCR system receives the start signal of the hybrid vehicle and conducts self-check. If the self-check result is no fault, it determines whether the SCR system meets the preset heating and thawing conditions.

[0013] Further, in one embodiment, the driving mode of the hybrid vehicle is determined according to the engine speed:

[0014] If the engine speed is greater than the preset speed, the driving mode of the hybrid vehicle is the engine driving mode.

[0015] If the engine speed is less than or equal to the preset speed, the driving mode of the hybrid vehicle is the pure electric driving mode.

[0016] Further, in one embodiment, during the process of starting the electronic water pump to circulate the engine coolant to heat and thaw the urea tank, it further includes:

[0017] Continuously determine whether the engine coolant temperature is less than the second preset coolant temperature. If so, switch to the engine driving mode to heat and thaw the urea tank; if not, continue to use the electronic water pump to circulate the engine coolant to heat and thaw the urea tank until the heating and thawing stops.

[0018] Further, in one embodiment, the pressure build-up condition is: the temperature of the urea pump is greater than the preset urea pump temperature, and the temperature of the urea tank is greater than the preset urea tank temperature.

[0019] Further, in one embodiment, if the actual pressure build-up time is greater than the preset pressure build-up time, the pressure build-up fails; otherwise, the pressure build-up is successful.

[0020] Further, in one embodiment, if the pressure build-up fails continuously within the preset number of times, stop heating and thawing the urea pump, urea pipe and urea tank, and report the pressure build-up failure fault information.

[0021] Further, in one embodiment, if the SCR system does not reach the pressure build-up condition within the preset time, stop heating and thawing the urea pump, urea pipe and urea tank, and report the heating and thawing failure fault information.

[0022] In a second aspect, based on the above SCR system heating and thawing control method, the present application provides a heating and thawing control system for the SCR system heating and thawing control method. The system includes:

[0023] A heating and thawing start module, which is used to start and continuously heat and thaw the urea pump and urea pipes when the SCR system meets the preset heating and thawing conditions.

[0024] An engine drive module, which is used to directly heat and thaw the urea tank through the engine coolant in the engine drive mode while the heating and thawing start module starts and continuously heats and thaws the urea pump and urea pipes.

[0025] A pure electric drive module, which is used to start the electronic water pump to circulate the engine coolant to heat and thaw the urea tank in the pure electric drive mode while the heating and thawing start module starts and continuously heats and thaws the urea pump and urea pipes, when the engine coolant temperature is greater than the first preset coolant temperature; otherwise, switch to the engine drive mode for heating and thawing.

[0026] A pressure building module, which is used to build pressure for the SCR system under the pressure building conditions during heating and thawing, and stop heating and thawing when the pressure building is successful.

[0027] The beneficial effects brought by the technical solution provided by the embodiment of the present application include:

[0028] When the SCR system meets the preset heating and thawing conditions in the present application, start and continuously heat and thaw the urea pump and urea pipes; at the same time, directly heat and thaw the urea tank through the engine coolant in the engine drive mode; in the pure electric drive mode, when the engine coolant temperature is greater than the first preset coolant temperature, start the electronic water pump to circulate the engine coolant to heat and thaw the urea tank; otherwise, switch to the engine drive mode for heating and thawing. Considering the SCR system heating and thawing control method of hybrid vehicles in different drive modes, the reliability of the SCR system heating and thawing control technology of hybrid vehicles is effectively improved. Description of the Drawings

[0029] Figure 1 It is a flowchart of the SCR system heating and thawing control method according to the embodiment of the present application.

[0030] Figure 2 It is a detailed flowchart of step S7 according to the embodiment of the present application.

[0031] Figure 3 It is a block diagram of the SCR system heating and thawing control system according to the embodiment of the present application. Detailed Embodiments

[0032] To enable those skilled in the art to better understand the solution of this application, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of this application. Obviously, the described embodiments are only a part of the embodiments of this application, rather than all the embodiments. Based on the embodiments in this application, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of this application.

[0033] First, some technical terms in this application are explained to facilitate the understanding of this application by those skilled in the art.

[0034] (1) SCR: Selective Catalytic Reduction technology, which is an efficient flue gas denitrification technology. This technology uses the function of a catalyst to reduce NO x (nitrogen oxides) in flue gas to harmless N2 (nitrogen) and H2O (water) at a relatively low temperature (usually 200 - 400 °C).

[0035] (2) Time limit required by the national VI emission regulations for heavy-duty vehicles: With the implementation of the national VI emission regulations for heavy-duty vehicles, clear requirements are made for the low-temperature performance of the SCR system, that is, production enterprises should ensure that the urea solution can be used within 70 minutes after the vehicle starts running under the condition that the ambient temperature is -17 °C.

[0036] The current heating and thawing control system for the SCR (Selective Catalytic Reduction) system controls heating and thawing based on the temperature data collected by any one of the urea temperature of the urea pump, the temperature sensor of the urea tank, and the ambient temperature sensor. In the case of partial sensor failures, the system can still continue to control heating and thawing relying on the temperature data collected by other sensors, thus making the entire urea heating and thawing control stable and reliable, effectively ensuring the urea heating and thawing effect. However, this system is only applicable to pure fuel vehicle models and does not consider the applicability of hybrid vehicle models.

[0037] Especially in the SCR system of hybrid vehicle models that rely on engine coolant for heating and thawing, in a low-temperature environment, when the vehicle is in pure electric drive mode (the engine is stopped and there is no coolant circulation), it is difficult to carry out the heating and insulation work of the urea tank, and there is a risk of being unable to build pressure for the SCR system normally for a long time.

[0038] Secondly, this system does not introduce the coolant temperature parameter as a judgment condition for starting heating and thawing, and there is a risk that the heating and thawing of the SCR system exceeds the time limit required by the regulations.

[0039] Based on the above technical status quo, the present application provides a heating and thawing control method and system for an SCR system, aiming to solve the problem that the current heating and thawing control technology for SCR systems is mainly used in traditional fuel vehicles, and the applicability of hybrid vehicles has not been fully considered, resulting in poor reliability of the SCR system heating and thawing technology in hybrid vehicles.

[0040] To make the objectives, technical solutions, and advantages of the present application clearer, the following will further describe the embodiments of the present application in detail with reference to the accompanying drawings.

[0041] In a first aspect, an embodiment of the present application provides a heating and thawing control method for an SCR system.

[0042] In this embodiment, as shown in Figure 1 the above heating and thawing control method includes:

[0043] S1. When the SCR system meets the preset heating and thawing conditions, start and continuously heat and thaw the urea pump and urea pipe. At the same time, judge the driving mode of the hybrid vehicle according to the engine speed. When the driving mode of the hybrid vehicle is the engine driving mode, enter step S2; when the driving mode of the hybrid vehicle is the pure electric driving mode, enter step S3. Among them, at the moment when the heating and thawing starts, start the timer to start timing.

[0044] S2. Directly heat and thaw the urea tank through the engine coolant, and enter step S7.

[0045] S3. Judge whether the engine coolant temperature is greater than the first preset coolant temperature. If so, enter step S4; if not, enter step S8.

[0046] S4. Start the electronic water pump to circulate the engine coolant to heat and thaw the urea tank, and enter step S5.

[0047] S5. Continuously judge whether the engine coolant temperature is less than the second preset coolant temperature. If so, enter step S8; if not, enter step S6.

[0048] S6. Continue to heat and thaw the urea tank by means of the electronic water pump circulating the engine coolant.

[0049] S7. Continuously build pressure for the SCR system. When the pressure building is successful, stop the heating and thawing, and this process ends.

[0050] S8. Switch to the engine driving mode and enter step S2.

[0051] In this embodiment, when the SCR system meets the preset heating and thawing conditions, the heating and thawing of the urea pump and urea pipe are started and continued. At the same time, the driving mode of the hybrid vehicle is determined according to the engine speed. When the driving mode of the hybrid vehicle is the engine driving mode, the urea tank is directly heated and thawed by the engine coolant. When the driving mode of the hybrid vehicle is the pure electric driving mode, it is judged whether the engine coolant temperature is greater than the first preset coolant temperature. If so, the electronic water pump is started to circulate the engine coolant to heat and thaw the urea tank. If not, the driving mode is switched to the engine driving mode, and the urea tank is directly heated and thawed by the engine coolant again.

[0052] In this embodiment, a heating and thawing control method for the SCR system of a hybrid vehicle is comprehensively considered under different driving modes (i.e., the engine driving mode and the pure electric driving mode). In the pure electric driving mode, the urea tank can also be heated and thawed by the engine coolant, effectively improving the reliability of the heating and thawing control technology of the SCR system of the hybrid vehicle.

[0053] Especially in the pure electric driving mode, during the process of starting the electronic water pump to circulate the engine coolant to heat and thaw the urea tank, the engine coolant temperature is continuously monitored. When the engine coolant temperature is lower than the second preset coolant temperature, the driving mode is switched to the engine driving mode to heat and thaw the urea tank. Thus, to a certain extent, the problem that the heating and thawing process of the urea tank cannot continue due to too low engine coolant temperature during the heating and thawing process is avoided.

[0054] Further, in one embodiment, the preset heating and thawing conditions in the above step S1 are: the urea tank temperature is less than the first preset heating and thawing temperature, the engine coolant temperature is greater than the second preset heating and thawing temperature, the ambient temperature is less than the first preset heating and thawing temperature, or the urea pump temperature is less than the first preset heating and thawing temperature. Both the first preset heating and thawing temperature and the second preset heating and thawing temperature are set according to the vehicle development requirements. In this embodiment, the first preset heating and thawing temperature is -7°C, and the second preset heating and thawing temperature is 10°C.

[0055] In this embodiment, when at least any one of the above heating conditions is met, the heating and thawing process of the SCR system is started, that is, the heating and thawing of the urea pump and urea pipe are started and continued. And this embodiment introduces the engine coolant temperature as a temperature parameter for judging the start of heating and thawing, avoiding the risk of heating and thawing exceeding the regulatory requirements time limit to a certain extent.

[0056] Further, in one embodiment, before judging that the SCR system in the above step S1 meets the preset heating and thawing conditions, the following steps are further included:

[0057] The SCR system receives the start signal of the hybrid vehicle, i.e., the power-on signal of the vehicle key. The SCR system performs self-check. If the self-check result is no fault, it further determines whether the SCR system meets the preset heating and thawing conditions. If it meets, heating and thawing are carried out. If it does not meet, continuous self-check is performed. If the self-check result is a fault, after repairing the fault of the SCR system, the SCR system continues to receive the start signal of the hybrid vehicle and performs self-check until the self-check result is no fault.

[0058] In this embodiment, the DCU (DeNox Control Unit, urea injection control unit) of the SCR system receives the start signal of the hybrid vehicle. When it receives the start signal of the hybrid vehicle, the SCR system starts to perform fault self-check. If the self-check result is no fault, the DCU receives the urea tank temperature signal, engine coolant temperature signal, ambient temperature signal, and urea pump temperature signal transmitted by the temperature sensor or ECU (Electronic Control Unit), and determines whether the SCR system meets the preset heating and thawing conditions according to these temperature signals. If the self-check result is a fault, the above temperature signals are not received.

[0059] Further, in one embodiment, in the above step S1, the method for determining the driving mode of the hybrid vehicle according to the engine speed is as follows:

[0060] Compare the engine speed with the preset speed. If the engine speed is greater than the preset speed, the driving mode of the hybrid vehicle is determined as the engine driving mode. If the engine speed is less than or equal to the preset speed, the driving mode of the hybrid vehicle is determined as the pure electric driving mode.

[0061] Further, in one embodiment, as shown in Figure 2 During the heating and thawing process in the above step S7, the SCR system is continuously pressurized under the pressure building condition, and the heating and thawing stop when the pressure building is successful, including the following steps:

[0062] S701. Determine whether the SCR system meets the pressure building condition. If yes, go to step S702. If no, go to step S707.

[0063] S702. Pressurize the SCR system.

[0064] During the process of pressurizing the SCR system in this step, the heating and thawing of the urea pipe, urea tank, and urea pump are continuously carried out.

[0065] S703. Determine whether the pressurization of the SCR system is successful. If yes, go to step S704. If no, go to step S705.

[0066] S704. Stop the heating and thawing of the urea pipe, urea tank, and urea pump.

[0067] S705. Determine whether the number of pressure build - up times reaches the preset continuous number. If so, proceed to step S706; if not, transfer to step S702.

[0068] S706. Stop heating and thawing the urea pump, urea pipe, and urea tank, and report a pressure build - up failure fault message.

[0069] S707. Determine whether the timer reaches the preset timing time. If so, proceed to step S708; if not, transfer to step S701.

[0070] S708. Stop heating and thawing the urea pump, urea pipe, and urea tank, and report a heating and thawing failure fault message.

[0071] In this embodiment, during the heating and thawing process, continuously determine whether the SCR system meets the pressure build - up conditions. When the SCR system meets the pressure build - up conditions, perform pressure build - up on the SCR system. If the pressure build - up is successful, it means that the heating and thawing of the SCR system is successful, and stop heating and thawing the urea pipe, urea tank, and urea pump. By performing pressure build - up on the SCR system within the SCR system and using successful pressure build - up as a sign of successful heating and thawing, the reliability of the method of this application can be effectively proven.

[0072] Further, in one embodiment, the pressure build - up conditions in the above - mentioned step S701 are: the temperature of the urea pump is greater than the preset urea pump temperature, and the temperature of the urea tank is greater than the preset urea tank temperature. The temperature of the urea pump and the temperature of the urea tank can be set according to vehicle development requirements. In this embodiment, the preset urea pump temperature is 5 °C, and the preset urea tank temperature is - 5 °C.

[0073] Further, in one embodiment, in the above - mentioned step S703, the method for determining whether the pressure build - up of the SCR system is successful is: preset a pressure build - up time. If the pressure build - up time of the current pressure build - up process is greater than the preset pressure build - up time, the pressure build - up fails; if the pressure build - up time of the current pressure build - up process is less than or equal to the preset pressure build - up time, the pressure build - up is successful.

[0074] Further, in one embodiment, the preset continuous number is 5 times, the preset pressure build - up time interval is 1 minute, and the preset pressure build - up time is 40 s. In the above - mentioned step S7, during the heating and thawing process, another implementation manner in which the SCR system continuously performs pressure build - up on the SCR system under the pressure build - up conditions and stops heating and thawing when the pressure build - up is successful includes the following steps:

[0075] S711. Determine whether the temperature of the urea pump is greater than the preset urea pump temperature and the temperature of the urea tank is greater than the preset urea tank temperature. If so, the pressure build - up conditions are met, and proceed to step S712; if not, the pressure build - up conditions are not met, and proceed to step S716.

[0076] S712. The SCR system enters the pressure - building program and starts building pressure.

[0077] S713. The SCR system enters the pressure - building result judgment program to judge whether the pressure - building times at intervals of 1 minute for 5 consecutive times are all greater than 40 s. If so, go to step S714; if not, go to step S715.

[0078] S714. Report a pressure - building failure fault message.

[0079] S715. The pressure - building is successful.

[0080] S716. Judge whether the timer reaches the preset timing time. If so, go to step S717; if not, transfer to step S711.

[0081] S717. Stop heating and thawing the urea pump, urea pipe and urea tank, and report a heating and thawing failure fault message.

[0082] In a second aspect, based on the above SCR system heating and thawing control method, an embodiment of an SCR system heating and thawing control system is provided. Refer to Figure 3 As shown, the above - mentioned system includes a heating and thawing start module, an engine - driven module, a pure - electric - driven module and a pressure - building module. Specifically:

[0083] The heating and thawing start module is used to start and continuously heat and thaw the urea pump and urea pipe when the SCR system meets the preset heating and thawing conditions.

[0084] The engine - driven module is used to directly heat and thaw the urea tank through the engine coolant in the engine - driven mode while the heating and thawing start module starts and continuously heats and thaws the urea pump and urea pipe.

[0085] The pure - electric - driven module is used to start the electronic water pump to circulate the engine coolant to heat and thaw the urea tank in the pure - electric - driven mode while the heating and thawing start module starts and continuously heats and thaws the urea pump and urea pipe, when the engine coolant temperature is greater than the first preset coolant temperature; otherwise, switch to the engine - driven mode for heating and thawing.

[0086] The pressure - building module is used to build pressure on the SCR system under the pressure - building conditions during heating and thawing, and stop heating and thawing when the pressure - building is successful.

[0087] Furthermore, in an embodiment, the above - mentioned system may further include a mode determination module and a judgment module. Specifically:

[0088] A mode determination module, which is used to determine the driving mode of a hybrid vehicle according to the engine speed. If the engine speed is greater than the preset speed, the driving mode of the hybrid vehicle is the engine driving mode in the engine driving module. If the engine speed is less than or equal to the preset speed, the driving mode of the hybrid vehicle is the pure electric driving mode in the pure electric driving module.

[0089] A judgment module, which is used to continuously judge whether the engine coolant temperature is less than the second preset coolant temperature during the process of starting the electronic water pump in the pure electric driving module to circulate the engine coolant to heat and thaw the urea tank. If so, switch to the engine driving mode in the engine driving module to heat and thaw the urea tank; if not, continue to use the method of circulating the engine coolant by the electronic water pump in the pure electric driving module to heat and thaw the urea tank until the heating and thawing stops.

[0090] This application uses the vehicle key power-on and power-off signals as the judgment method for the start and end of the DCU to control the SCR system, avoiding the interruption of the DCU control caused by the frequent switching of the two power modes of the hybrid vehicle. Using the urea pipe temperature, urea pump temperature, urea tank temperature, and engine coolant temperature as the judgment elements for the start of heating and thawing effectively reduces the risk that the heating and thawing of the SCR system exceeds the regulatory requirements time limit. By distinguishing the engine driving mode and the pure electric driving mode through the engine speed, the urea tank can be heated by the engine coolant in both modes, improving the applicability and reliability of the method of this application in hybrid vehicles. Especially in the pure electric driving mode, the engine is in a shutdown state and there is no coolant circulation. At this time, by starting the electronic water pump to circulate the engine coolant, using the temperature of the engine coolant to heat and thaw the urea tank not only reduces the running time of the fuel power mode but also realizes energy conservation and environmental protection.

[0091] To reduce the heating and thawing failures of the SCR system, the industry usually adopts the method of changing the hardware. For example, changing the urea tank to electric heating and integrating the control of the SCR system heating and thawing, but this increases the power consumption and the complexity of the vehicle's circuit system; adding hardware so that all components of the SCR system can have both electric heating and coolant heating and thawing functions and determining the heating and thawing mode according to the working conditions. This method increases the complexity of the SCR system and also increases the cost.

[0092] The SCR system heating and thawing control method and system provided by this application, based on the current situation of industry application products, fully identify the problems existing in existing products without changing the original hardware design and solve them through simple and effective control methods, belonging to the use of intelligent and economical means to achieve the safe and reliable operation of products.

[0093] In the initial stage of the development of a certain hybrid vehicle project, when the conventional SCR system heating and thawing method was adopted, due to the frequent switching between the two power modes, the heating and thawing operation stopped frequently, resulting in frequent failures of the heating and thawing, seriously affecting the normal operation of the SCR system in cold regions. By adopting the SCR system heating and thawing control method provided in this application, while effectively avoiding the occurrence of heating and thawing failures of the SCR system, the heating and thawing of the entire system is realized with intelligence and light weight.

[0094] It should be noted that the serial numbers of the embodiments of this application above are only for description and do not represent the advantages or disadvantages of the embodiments.

[0095] The terms "including" and "having" and any variations thereof in the description of the embodiments of this application, as well as in the claims and the above-mentioned drawings, are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device that includes a series of steps or units is not limited to the listed steps or units, but may optionally further include steps or units not listed, or may optionally further include other steps or units inherent to these processes, methods, products or devices. The descriptions of terms such as "first", "second" and "third" are used to distinguish different objects, etc., and do not represent a sequence, nor do they limit that "first", "second" and "third" are of different types.

[0096] In the description of the embodiments of this application, words such as "exemplary", "for example" or "for illustration" are used to indicate examples, illustrations or explanations. Any embodiment or design solution described as "exemplary", "for example" or "for illustration" in the embodiments of this application should not be construed as being more preferred or having more advantages than other embodiments or design solutions. Rather, the use of words such as "exemplary", "for example" or "for illustration" is intended to present the relevant concepts in a specific manner.

[0097] In the description of the embodiments of this application, unless otherwise specified, " / " means "or". For example, A / B may mean A or B; "and / or" in the text is only a description of the association relationship of the associated objects, indicating that there can be three relationships. For example, A and / or B may mean: A exists alone, A and B exist simultaneously, and B exists alone. In addition, in the description of the embodiments of this application, "a plurality of" means two or more than two.

[0098] In some of the processes described in the embodiments of this application, multiple operations or steps appear in a specific order. However, it should be understood that these operations or steps may not be executed in the order in which they appear in the embodiments of this application or may be executed in parallel. The serial numbers of the operations are only used to distinguish different operations, and the serial numbers themselves do not represent any execution order. Additionally, these processes may include more or fewer operations, and these operations or steps may be executed in sequence or in parallel, and these operations or steps may be combined.

[0099] Through the description of the above embodiments, those skilled in the art can clearly understand that the above-described embodiment methods can be implemented by means of software plus a necessary general hardware platform. Of course, they can also be implemented by hardware, but in many cases the former is a better implementation method. Based on such an understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product is stored in a storage medium as described above (such as ROM / RAM, magnetic disk, optical disc) and includes several instructions for causing a terminal device to execute the methods described in various embodiments of this application.

[0100] The above are only the preferred embodiments of this application, and do not limit the patent scope of this application. Any equivalent structural or equivalent process transformation made by using the content of the specification and drawings of this application, or directly or indirectly applied in other related technical fields, shall be equally included in the patent protection scope of this application.

Claims

1. A heating and thawing control method for an SCR system, characterized in that, The method includes: When the SCR system meets the preset heating and thawing conditions, start and continuously heat and thaw the urea pump and urea pipes; meanwhile, In the engine drive mode, directly heat and thaw the urea tank through the engine coolant; In the pure electric drive mode, when the engine coolant temperature is greater than the first preset coolant temperature, start the electronic water pump to circulate the engine coolant to heat and thaw the urea tank; otherwise, switch to the engine drive mode for heating and thawing; During heating and thawing, build pressure for the SCR system under the pressure build-up conditions, and stop heating and thawing when the pressure build-up is successful.

2. The SCR system heating and thawing control method according to claim 1, wherein, The preset heating and thawing conditions are: The urea tank temperature is less than the first preset heating and thawing temperature, the engine coolant temperature is greater than the second preset heating and thawing temperature, the ambient temperature is less than the first preset heating and thawing temperature, or the urea pump temperature is less than the first preset heating and thawing temperature.

3. The SCR system heating and thawing control method according to claim 1, characterized in that Before determining that the SCR system meets the preset heating and thawing conditions, it also includes: The SCR system receives the start signal of the hybrid vehicle and performs self-check. If the self-check result is no fault, determine whether the SCR system meets the preset heating and thawing conditions.

4. The SCR system heating and thawing control method according to claim 1, characterized in that Determine the hybrid vehicle drive mode according to the engine speed: If the engine speed is greater than the preset speed, the hybrid vehicle drive mode is the engine drive mode; If the engine speed is less than or equal to the preset speed, the hybrid vehicle drive mode is the pure electric drive mode.

5. The SCR system heating and thawing control method according to claim 1, characterized in that, During the process of starting the electronic water pump to circulate the engine coolant to heat and thaw the urea tank, it also includes: Continuously determine whether the engine coolant temperature is less than the second preset coolant temperature. If so, switch to the engine drive mode to heat and thaw the urea tank; if not, continue to use the electronic water pump to circulate the engine coolant to heat and thaw the urea tank until the heating and thawing stops.

6. The SCR system heating and thawing control method according to claim 1, characterized in that The pressure build-up conditions are: the urea pump temperature is greater than the preset urea pump temperature, and the urea tank temperature is greater than the preset urea tank temperature.

7. The heating and thawing control method of the SCR system according to claim 1, characterized in that If the actual pressure build-up time is greater than the preset pressure build-up time, the pressure build-up fails; otherwise, the pressure build-up is successful.

8. The SCR system heating and thawing control method according to claim 7, wherein, If the pressure build-up fails within the preset number of consecutive times, stop heating and thawing the urea pump, urea pipes and urea tank, and report the pressure build-up failure fault information.

9. The SCR system heating and thawing control method according to claim 1, wherein, If the SCR system does not reach the pressure build-up conditions within the preset time, stop heating and thawing the urea pump, urea pipes and urea tank, and report the heating and thawing failure fault information.

10. A heating and thawing control system for the SCR system heating and thawing control method according to any one of claims 1-9, characterized in that, The system includes: A heating and thawing start module, which is used to start and continuously heat and thaw the urea pump and urea pipes when the SCR system meets the preset heating and thawing conditions; An engine drive module, which is used to directly heat and thaw the urea tank through the engine coolant in the engine drive mode while the heating and thawing start module starts and continuously heats and thaws the urea pump and urea pipes; A pure electric drive module, which is used to start the electronic water pump to circulate the engine coolant to heat and thaw the urea tank in the pure electric drive mode while the heating and thawing start module starts and continuously heats and thaws the urea pump and urea pipes; otherwise, switch to the engine drive mode for heating and thawing; A pressure building module, which is used to build pressure for the SCR system under pressure building conditions during heating and thawing, and stops heating and thawing when the pressure building is successful.

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