Diesel engine aftertreatment system, vehicle and control method

Abstract

The invention provides a diesel engine aftertreatment system, a vehicle and a control method. According to the system, after the preceding-stage SCR temperature obtained by the temperature sensor is transmitted to the control unit, the control unit controls the opening degree of the first airflow valves arranged at the inlets of the first gas channel and the second gas channel according to the preceding-stage SCR temperature. When the tail gas does not need to be heated through the electric heating equipment, the control unit controls the opening degree of the first airflow valve to adjust the gas amount of the tail gas entering the first gas passage and the second gas passage, so that the gas amount passing through the electric heating equipment in the second gas passage is closed; therefore, part of power and tail gas heat of the electric heating equipment are prevented from being wasted, meanwhile, the problem that rated power is reduced due to carbon deposition on the surface of the electric heating equipment when the tail gas passes through the electric heating equipment for a long time is solved, and the reliability and durability of the whole aftertreatment system are improved.

Description

Technical Field

[0001] The present application relates to the technical field of engine aftertreatment, and in particular to a diesel engine aftertreatment system, a vehicle and a control method. Background Art

[0002] In order to meet the current requirements for environmental protection and exhaust emissions, existing solutions usually use a nitrogen oxide removal system with a selective catalytic reducer as the core as the main vehicle exhaust treatment solution for widespread use in various current vehicles.

[0003] For a nitrogen oxide removal system with a selective catalytic reducer as the core, the working efficiency is low when the working temperature is in a low temperature range. Therefore, the existing treatment scheme usually adds an electric heating device in front of the selective catalytic reducer to increase the working temperature of the selective catalytic reducer.

[0004] However, since the electric heating equipment itself is made of metal and has high heat dissipation efficiency, not only will the heat dissipation itself waste some power, but it is also easy for carbon to accumulate on the surface of the electric heating equipment, resulting in a reduction in the rated power, thereby reducing the reliability and durability of the nitrogen oxide removal system. Summary of the invention

[0005] The embodiments of the present application provide a diesel engine aftertreatment system, a vehicle and a control method to solve the defects of poor reliability and durability of the nitrogen oxide removal system caused by power waste caused by electric heating equipment made of metal materials and reduced rated power due to carbon deposits in existing treatment solutions.

[0006] In a first aspect, an embodiment of the present application provides a diesel engine aftertreatment system, comprising:

[0007] A control unit, a first gas passage, a second gas passage, a post-treatment passage, and a temperature sensor disposed at a front-stage selective catalytic reducer SCR in the post-treatment passage, wherein the first gas passage and the second gas passage are two parallel passages connected at an inlet and an outlet, a first gas flow valve is disposed at the inlet, and the outlet is connected to the post-treatment passage;

[0008] A heating device is provided on the second gas passage, and the first airflow valve is communicatively connected to the control unit. The control unit is used to control the first airflow valve according to the relationship between the previous SCR temperature sent by the temperature sensor and the preset temperature to adjust the gas passing through the first gas passage and the second gas passage.

[0009] In a possible implementation, the heating device is coated with an oxidizing catalyst for oxidizing hydrocarbon substances attached to the surface of the heating device.

[0010] In a possible implementation, the heating device is communicatively connected to the control unit, and the control unit is further used to control the heating device to operate when the second gas passage is opened, and to control the heating device to stop operating when the second gas passage is closed.

[0011] In a possible implementation, a second air flow valve is provided at the outlet, and the second air flow valve is communicatively connected to the control unit, and the control unit is used to keep the states of the first air flow valve and the second air flow valve consistent.

[0012] In a possible implementation manner, the post-treatment passage includes: the front-stage SCR, the oxidation catalytic converter DOC, the particulate trap DPF and the rear-stage SCR arranged in sequence.

[0013] In a possible implementation, a silencer module and / or a gas mixing module is provided on the first gas passage.

[0014] In a second aspect, an embodiment of the present application provides a vehicle, comprising the above-mentioned diesel engine after-treatment system.

[0015] In a third aspect, an embodiment of the present application provides a control method for a diesel engine aftertreatment system, which is applied to the above diesel engine aftertreatment system, comprising:

[0016] The control unit receives the front-stage SCR temperature sent by the temperature sensor, and compares the front-stage SCR temperature with a preset temperature stored locally in the control unit;

[0017] The control unit controls the first gas flow valve according to the magnitude relationship between the front-stage SCR temperature and the preset temperature to adjust the amount of gas passing through the first gas passage and the second gas passage.

[0018] In a possible implementation manner, a first temperature difference between the front-stage SCR temperature and the preset temperature is calculated;

[0019] determining a target opening of the first gas flow valve toward the first gas passage according to the first temperature difference, wherein the first temperature difference is positively correlated with the target opening;

[0020] The first air flow valve is controlled according to the target opening.

[0021] In a possible implementation, a second air flow valve is provided at the outlet, and the second air flow valve is communicatively connected to the control unit, further comprising:

[0022] The control unit controls the second air flow valve according to the target opening degree.

[0023] In a possible implementation, the control unit controls the heating device to operate when the second gas passage is opened, and controls the heating device to stop operating when the second gas passage is closed.

[0024] In a possible implementation manner, the heating device includes a plurality of devices, and when the control unit opens the second gas passage, the control unit controls the heating device to operate, including:

[0025] The control unit determines a second temperature difference between the preset temperature and the front-stage SCR temperature;

[0026] The control unit determines a heating strategy according to the second temperature difference, wherein the heating strategy includes the number of heating devices and the working power, and the number of heating devices, the working power and the second temperature difference are positively correlated;

[0027] The control unit selects a target heating device from the plurality of heating devices according to the number of the heating devices, so as to control the target heating device to operate at the operating power.

[0028] In a possible implementation manner, the control unit acquires state information, and the state information includes at least one of the following: exhaust flow, exhaust temperature, engine speed, and engine torque;

[0029] The control unit obtains the preset temperature corresponding to the state information from a preset mapping list locally stored in the control unit, wherein the preset mapping list includes a relationship between the state information and the preset temperature.

[0030] The present application provides a diesel engine aftertreatment system, a vehicle and a control method. After the pre-stage SCR temperature obtained by the temperature sensor is transmitted to the control unit, the control unit controls the opening of the first airflow valve set at the entrance of the first gas passage and the second gas passage according to the pre-stage SCR temperature. When it is not necessary to heat the exhaust gas through the electric heating device, the control unit adjusts the amount of exhaust gas entering the first gas passage and the second gas passage by controlling the opening of the first airflow valve to close the amount of gas passing through the electric heating device in the second gas passage, thereby avoiding wasting part of the power of the electric heating device and the heat of the exhaust gas, and at the same time avoiding the problem of carbon accumulation on the surface of the electric heating device when the exhaust gas passes through the electric heating device for a long time, resulting in a reduction in the rated power, thereby improving the reliability and durability of the overall aftertreatment system. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0032] Figure 1 Schematic diagram of the diesel engine aftertreatment system provided for this application Figure 1 ;

[0033] Figure 2 Schematic diagram of the diesel engine aftertreatment system provided for this application Figure 2 ;

[0034] Figure 3 Schematic diagram of the control method of the diesel engine aftertreatment system provided in this application Figure 1 ;

[0035] Figure 4 Schematic diagram of the control method of the diesel engine aftertreatment system provided in this application Figure 2 .

[0036] Reference numerals: 1- Control unit; 2-first gas passage; 201-muffler module; 202-gas mixing module; 3- Second gas passage; 4- after-treatment passage; 401- front stage SCR; 402- oxidation catalytic converter DOC; 403- particulate trap DPF; 404- rear stage SCR; 5-temperature sensor; 6-first air flow valve; 7-heating device; 8-second air flow valve.

[0037] The above drawings have shown clear embodiments of the present application, which will be described in more detail later. These drawings and text descriptions are not intended to limit the scope of the present application in any way, but to illustrate the concept of the present application to those skilled in the art by referring to specific embodiments. DETAILED DESCRIPTION

[0038] Exemplary embodiments will be described in detail herein, examples of which are shown in the accompanying drawings. When the following description refers to the drawings, the same numbers in different drawings represent the same or similar elements unless otherwise indicated. The implementations described in the following exemplary embodiments do not represent all implementations consistent with the present application. Instead, they are merely examples of devices and methods consistent with some aspects of the present application as detailed in the appended claims.

[0039] It should be noted that the user information (including but not limited to user device information, user personal information, etc.) and data (including but not limited to data used for analysis, stored data, displayed data, etc.) involved in one or more embodiments of this specification are all information and data authorized by the user or fully authorized by all parties, and the collection, use and processing of relevant data must comply with relevant laws, regulations and standards, and corresponding operation entrances shall be provided for users to choose to authorize or refuse.

[0040] It should be noted that in the embodiments of the present application, certain software, components, models and other existing solutions in the industry may be mentioned, and they should be regarded as exemplary. Their purpose is only to illustrate the feasibility of implementing the technical solution of the present application, but it does not mean that the applicant has or will necessarily use the solution.

[0041] As society's requirements for environmental protection continue to increase, the corresponding vehicle exhaust emission regulations are also constantly increasing. Therefore, the current vehicle exhaust treatment system can no longer meet the ever-increasing vehicle exhaust emission regulations. The current vehicle diesel engine aftertreatment system includes DOC (Diesel Oxidation Catalyst) + DPF (Diesel Particulate Filter) + SCR (Selective Catalytic Reduction).

[0042] In order to meet the ever-increasing requirements of vehicle exhaust emission regulations, existing solutions usually use a dual-injection SCR after-treatment system to treat vehicle exhaust gas, where the dual-injection SCR after-treatment solution includes a front-stage SCR (Selective Catalytic Reduction) + DOC (Diesel Oxidation Catalyst) + DPF (Diesel Particulate Filter) + a rear-stage SCR.

[0043] However, the SCR nitrogen oxide removal reaction in the dual-injection SCR after-treatment system is limited by the ambient temperature. When the operating temperature is in the low temperature range, such as less than 220 degrees Celsius, the reaction efficiency is low, which in turn reduces the working efficiency of the entire system.

[0044] Therefore, in order to improve the SCR reaction efficiency in low-temperature conditions such as vehicle cold start, the existing treatment scheme usually adds an electric heating device in front of the catalyst device to increase the exhaust temperature. However, the electric heating device is mostly made of metal and has high heat dissipation efficiency. Not only will the heat dissipation itself waste some power and exhaust heat, but it is also prone to carbon accumulation on the surface, resulting in a reduction in rated power, which in turn reduces the reliability and durability of the overall post-treatment system.

[0045] In view of this, the present application provides a diesel engine aftertreatment system, after the pre-stage SCR temperature obtained by the temperature sensor is transmitted to the control unit, the control unit controls the opening of the first airflow valve set at the entrance of the first gas passage and the second gas passage according to the pre-stage SCR temperature. When it is not necessary to heat the exhaust gas through the electric heating device, the control unit adjusts the amount of gas entering the first gas passage and the second gas passage by controlling the opening of the first airflow valve to close the amount of gas passing through the electric heating device in the second gas passage, thereby avoiding wasting part of the power of the electric heating device and the heat of the exhaust gas, and at the same time avoiding the problem of carbon accumulation on the surface of the electric heating device when the exhaust gas passes through the electric heating device for a long time, resulting in a reduction in the rated power, thereby improving the reliability and durability of the overall aftertreatment system.

[0046] The technical solution of the present application and how the technical solution of the present application solves the above-mentioned technical problems are described in detail below with specific embodiments. The following specific embodiments can be combined with each other, and the same or similar concepts or processes may not be repeated in some embodiments. The embodiments of the present application will be described below in conjunction with the accompanying drawings.

[0047] Figure 1 Schematic diagram of the diesel engine aftertreatment system provided for this application Figure 1 ,like Figure 1 As shown, the diesel engine aftertreatment system includes: a control unit 1, a first gas passage 2, a second gas passage 3, an aftertreatment passage 4 and a temperature sensor 5 arranged at a front selective catalytic reducer SCR in the aftertreatment passage 4.

[0048] The first gas passage 2 and the second gas passage 3 are two parallel passages connected at the inlet and the outlet, a first gas flow valve 6 is provided at the inlet, and the outlet is connected to the post-processing passage 4.

[0049] At least one heating device 7 is provided on the second gas passage 3, and the first air flow valve 6 is communicatively connected to the control unit 1, and the control unit 1 is used to control the first air flow valve 6 according to the relationship between the previous SCR temperature sent by the temperature sensor 5 and the preset temperature to adjust the gas passing through the first gas passage 2 and the second gas passage 3.

[0050] Furthermore, the post-treatment passage 4 includes: a front-stage SCR 401, an oxidation catalytic converter DOC 402, a particulate trap DPF 403 and a rear-stage SCR 404 arranged in sequence, wherein the injection devices corresponding to the front-stage SCR 401 and the rear-stage SCR 404 are controlled by the control unit 1 to operate.

[0051] Specifically, when the vehicle is cold-started, the exhaust gas generated by the vehicle is relatively low. After entering the diesel engine after-treatment system, when entering the after-treatment passage 4 through the first gas passage 2 or the second gas passage 3, the gas temperature at this time is detected by the temperature sensor 5, and the detected gas temperature is sent to the control unit 1. When the control unit 1 detects that the gas temperature is lower than the preset temperature, it controls the first gas flow valve 6 to move to the corresponding opening, opens the second gas passage 3, and controls the exhaust gas to enter the heating device 7 in the second gas passage 3 through the first gas flow valve 6 for heating, thereby ensuring that the front-stage SCR401 and the rear-stage SCR404 in the after-treatment passage 4 meet the working temperature when performing the nitrogen and oxygen removal reaction based on the heated exhaust gas temperature environment, thereby avoiding low reaction efficiency.

[0052] Furthermore, when the control unit 1 detects that the gas temperature is higher than the preset temperature, it controls the first airflow valve 6 to move to the corresponding opening, opens the first gas passage 2, and controls the exhaust gas to enter the first gas passage 2 through the first airflow valve 6, thereby avoiding heating the gas through the heating device 7. In addition, since the gas temperature is higher than the preset temperature at this time, the SCR nitrogen oxide removal reaction in the post-treatment passage 4 also meets the operating temperature, thereby reducing the rated power reduction caused by carbon deposition on the surface of the heating device 7 when the exhaust gas passes through the heating device 7 for a long time.

[0053] The embodiment of the present application provides a diesel engine aftertreatment system, which transmits the pre-stage SCR temperature obtained by the temperature sensor to the control unit, and then the control unit controls the opening of the first airflow valve set at the entrance of the first gas passage and the second gas passage according to the pre-stage SCR temperature. When it is not necessary to heat the exhaust gas through the electric heating device, the control unit adjusts the amount of exhaust gas entering the first gas passage and the second gas passage by controlling the opening of the first airflow valve to close the amount of gas passing through the electric heating device in the second gas passage, thereby avoiding wasting part of the power of the electric heating device and the heat of the exhaust gas, and at the same time avoiding the problem of carbon accumulation on the surface of the electric heating device when the exhaust gas passes through the electric heating device for a long time, resulting in a reduction in the rated power, thereby improving the reliability and durability of the overall aftertreatment system.

[0054] Figure 2 Schematic diagram of the diesel engine aftertreatment system provided for this application Figure 2 ,like Figure 2 As shown, the heating device 7 is communicatively connected to the control unit 1 , and the control unit 1 is further used to control the heating device 7 to work when the second gas passage 3 is opened, and to control the heating device 7 to stop working when the second gas passage 3 is closed.

[0055] Specifically, when the control unit 1 detects that the gas temperature is lower than the preset temperature, it controls the first airflow valve 6 to move to the corresponding opening, opens the second gas passage 3, and simultaneously controls the heating device 7 to operate, so as to control the exhaust gas to enter the heating device 7 in the second gas passage 3 through the first airflow valve 6 for heating.

[0056] When the control unit 1 detects that the gas temperature is higher than the preset temperature, it controls the first gas flow valve 6 to move to the corresponding opening, opens the first gas passage 2, and controls the heating device 7 to stop working at the same time, thereby avoiding heating of the gas by the heating device 7, saving the heating device 7 from working for a long time, and reducing the heat loss of the engine exhaust gas for heating or heat preservation of the heating device 7, thereby reducing the power consumed by turning on the electric heating to compensate for the loss of the electric heating itself, reducing engine fuel consumption, and improving product economy.

[0057] Furthermore, the heating device 7 is coated with an oxidizing catalyst for oxidizing hydrocarbons and particulate matter attached to the surface of the heating device.

[0058] Specifically, when the control unit 1 detects that the gas temperature is lower than the preset temperature, it opens the second gas passage 3 and controls the heating device 7 to work at the same time, so that when the exhaust gas enters the heating device 7 in the second gas passage 3, the nitrogen oxides in the exhaust gas can be processed and reduced in advance through the SCR catalyst coated on the heating device 7, so as to reduce the reaction burden of each level of SCR in the post-treatment passage 4.

[0059] Furthermore, a second air flow valve 8 is provided at the outlet, and the second air flow valve 8 is communicatively connected to the control unit 1 , and the control unit 1 is used to keep the states of the first air flow valve 6 and the second air flow valve 8 consistent.

[0060] Specifically, when the control unit 1 detects that the gas temperature is lower than the preset temperature, it controls the first airflow valve 6 and the second airflow valve 8 to move to the corresponding openings, opens the second gas passage 3, and simultaneously controls the heating device 7 to operate, so that the exhaust gas is controlled by the first airflow valve 6 to enter the heating device 7 in the second gas passage 3 for heating, and then enters the post-processing passage 4 under the guidance of the second airflow valve 8, so as to avoid the reverse transmission of the airflow into the first gas passage 2 when the back pressure of the post-processing passage 4 is large.

[0061] When the control unit 1 detects that the gas temperature is higher than the preset temperature, it controls the first air flow valve 6 and the second air flow valve 8 to move to the corresponding openings, opens the first gas passage 2, and enters the post-processing passage 4 under the guidance of the second air flow valve 8, so as to avoid the reverse transmission of the airflow into the second gas passage 3 when the back pressure of the post-processing passage 4 is large.

[0062] Furthermore, a silencer module 201 and / or a gas mixing module 202 is provided on the first gas passage 2 to eliminate the noise of the exhaust gas through the silencer module 201 .

[0063] The embodiment of the present application provides a diesel engine aftertreatment system, which transmits the pre-stage SCR temperature obtained by the temperature sensor to the control unit, and then the control unit controls the opening of the first airflow valve set at the entrance of the first gas passage and the second gas passage according to the pre-stage SCR temperature. When it is not necessary to heat the exhaust gas through the electric heating device, the control unit adjusts the amount of exhaust gas entering the first gas passage and the second gas passage by controlling the opening of the first airflow valve to close the amount of gas passing through the electric heating device in the second gas passage, thereby avoiding wasting part of the power of the electric heating device and the heat of the exhaust gas, and at the same time avoiding the problem of carbon accumulation on the surface of the electric heating device when the exhaust gas passes through the electric heating device for a long time, resulting in a reduction in the rated power, thereby improving the reliability and durability of the overall aftertreatment system.

[0064] Figure 3 Schematic diagram of the control method of the diesel engine aftertreatment system provided in this application Figure 1 ,like Figure 2 As shown, in this embodiment Figure 1 and Figure 2 Based on the embodiment, a control method of a diesel engine aftertreatment system is described in detail, and the method includes:

[0065] S101 . A control unit receives a pre-stage SCR temperature sent by the temperature sensor, and compares the pre-stage SCR temperature with a preset temperature stored locally in the control unit.

[0066] Specifically, when the vehicle is started, when the exhaust gas generated by the vehicle enters the post-processing passage 4 through the first gas passage 2 or the second gas passage 3, the gas temperature at this time, that is, the pre-stage SCR temperature, is collected by the temperature sensor 5, and the collected pre-stage SCR temperature is sent to the control unit 1. Of course, the control unit 1 can also obtain state information including exhaust flow, exhaust temperature, that is, pre-stage SCR temperature, engine speed and engine torque through different sensors.

[0067] Furthermore, the control unit obtains the preset temperature corresponding to the state information from a preset mapping list stored locally in the control unit, and the preset mapping list includes the relationship between the state information and the preset temperature.

[0068] S102. The control unit controls the first gas flow valve according to the relationship between the temperature of the front-stage SCR and the preset temperature to adjust the amount of gas passing through the first gas passage and the second gas passage.

[0069] Specifically, after the control unit 1 obtains the corresponding preset temperature according to the temperature of the front-stage SCR, it detects whether the temperature of the front-stage SCR is greater than the preset temperature. If so, the control unit 1 controls the first air flow valve 6 to move to the corresponding opening to open the first gas passage 2 and close the second gas passage 3, so that the gas passes through the first gas passage 2 into each catalyst in the post-treatment passage 4 for exhaust gas treatment.

[0070] Furthermore, if not, the control unit 1 controls the first air flow valve 6 to move to a corresponding opening to close the first gas passage 2 and open the second gas passage 3, so that the gas is heated by the heating device 7 in the second gas passage 3 and then enters the catalysts in the post-treatment passage 4 for exhaust gas treatment.

[0071] The embodiment of the present application provides a diesel engine aftertreatment system, which transmits the pre-stage SCR temperature obtained by the temperature sensor to the control unit, and then the control unit controls the opening of the first airflow valve set at the entrance of the first gas passage and the second gas passage according to the pre-stage SCR temperature. When it is not necessary to heat the exhaust gas through the electric heating device, the control unit adjusts the amount of exhaust gas entering the first gas passage and the second gas passage by controlling the opening of the first airflow valve to close the amount of gas passing through the electric heating device in the second gas passage, thereby avoiding wasting part of the power of the electric heating device and the heat of the exhaust gas, and at the same time avoiding the problem of carbon accumulation on the surface of the electric heating device when the exhaust gas passes through the electric heating device for a long time, resulting in a reduction in the rated power, thereby improving the reliability and durability of the overall aftertreatment system.

[0072] Figure 4 Schematic diagram of the control method of the diesel engine aftertreatment system provided in this application Figure 2 ,like Figure 4 As shown, in this embodiment Figure 3 Based on the embodiment, a control method of a diesel engine aftertreatment system is described in detail, and the method includes:

[0073] S201 . A control unit receives a pre-stage SCR temperature sent by the temperature sensor, and compares the pre-stage SCR temperature with a preset temperature stored locally in the control unit.

[0074] Specifically, when the vehicle is started, the vehicle sensor obtains state information, and in the preset mapping list, the corresponding preset temperature is obtained according to the state information. The vehicle sensor includes a flow sensor, a temperature sensor, a speedometer, and a torque sensor.

[0075] Furthermore, the exhaust flow rate of the exhaust gas at this time is obtained through the flow sensor, the exhaust temperature of the exhaust gas when it passes through the front-stage SCR, that is, the front-stage SCR temperature, is obtained through the temperature sensor, the engine speed at this time is obtained through the speedometer, and the output torque of the vehicle at this time is obtained through the torque sensor. The exhaust flow rate of the exhaust gas, the exhaust temperature of the exhaust gas when it passes through the front-stage SCR, the vehicle speed and the output torque are used as state information.

[0076] Further, with regard to the relationship between the state information and the preset temperature in the preset mapping list, the exhaust flow rate, exhaust temperature, engine speed and output torque in the state information are positively correlated with the preset temperature.

[0077] S202: Calculate a first temperature difference between the front-stage SCR temperature and the preset temperature.

[0078] Specifically, after the control unit 1 obtains the temperature of the front-stage SCR, if the temperature of the front-stage SCR is greater than or equal to the preset temperature, the difference between the temperature of the front-stage SCR and the preset temperature is obtained as the first temperature difference.

[0079] S203: Determine a target opening degree of the first gas flow valve toward the first gas passage according to the first temperature difference.

[0080] Specifically, after the first temperature difference is obtained, the temperature difference value identical to the first temperature difference is obtained in the first opening database of the control unit 1, and the corresponding opening value is determined according to the same temperature difference value as the target opening corresponding to the first temperature difference.

[0081] Among them, the first opening database is used to indicate the opening of the first airflow valve 6 and the second airflow valve 8 corresponding to the first temperature difference when the gas does not need to be heated. The first opening database pre-associately stores multiple groups of different temperature difference values ​​and opening values, wherein the temperature difference value and the opening value are positively correlated.

[0082] Among them, the target opening includes a first target opening and a second target opening. The first target opening is used to indicate the opening value of the first airflow valve 6, and the second target opening is used to indicate the opening value of the second airflow valve 8. When the first target opening and the second target opening are one hundred, the first gas passage 2 is fully opened and the second gas passage 3 is fully closed.

[0083] S204: Control the first airflow valve according to the target opening, and control the second airflow valve according to the target opening.

[0084] Specifically, after the control unit 1 obtains the target opening according to the first temperature difference, the control unit 1 controls the first air flow valve 6 to move to the first target opening, and the control unit 1 controls the second air flow valve 8 to move to the second target opening.

[0085] Furthermore, by controlling the opening of the first air flow valve 6 and the second air flow valve 8, the first gas passage 2 is opened, so that most of the gas or all of the gas passes through the first gas passage 2, and a small part of the gas or no gas passes through the second gas passage 3, and enters the post-processing passage 4 under the guidance of the second air flow valve 8, so as to avoid the reverse transmission of the airflow into the second gas passage 3 when the back pressure of the post-processing passage 4 is large.

[0086] S205 , the control unit determines a second temperature difference between the preset temperature and the temperature of the previous SCR.

[0087] Specifically, if the temperature of the front-stage SCR is lower than the preset temperature, the difference between the preset temperature and the temperature of the front-stage SCR is obtained as the second temperature difference, and the corresponding target opening is determined according to the second temperature difference, so that the control unit 1 controls the first airflow valve 6 and the second airflow valve 8 respectively according to the target opening.

[0088] Further, according to the second temperature difference, a temperature difference value identical to the second temperature difference is obtained in the second opening database of the control unit 1, and a corresponding opening value is determined according to the same temperature difference value as a target opening corresponding to the second temperature difference.

[0089] Among them, the second opening database is used to indicate the opening of the first airflow valve 6 and the second airflow valve 8 corresponding to the second temperature difference when the gas needs to be heated. The second opening database is pre-associated and stored with multiple sets of temperature differences and opening values. At this time, the temperature difference value is negatively correlated with the opening value.

[0090] The openings of the first air flow valve 6 and the second air flow valve 8 are controlled respectively according to the first target opening and the second target opening in the target opening. When the first target opening and the second target opening are zero, the second gas passage 3 is completely opened and the first gas passage 2 is completely closed, so that the gas is only heated by the heating device 7 in the second gas passage 3 without entering the first gas passage 2.

[0091] S206: The control unit determines a heating strategy according to the second temperature difference.

[0092] Specifically, after obtaining the second temperature difference, the temperature difference value identical to the second temperature difference is obtained in the strategy database of the control unit 1 according to the second temperature difference, and the corresponding strategy information is determined according to the same temperature difference value as the heating strategy, and a plurality of heating devices 7 are arranged in the second gas passage 3.

[0093] Among them, the strategy database is pre-associated and stored with multiple groups of different temperature difference values ​​and strategy information, the strategy information is used to indicate the working power and the number of heating devices required to reach the working temperature, the heating strategy includes the number of heating devices and the working power, and the number of heating devices, the working power and the second temperature difference are positively correlated.

[0094] S207: The control unit selects a target heating device from the plurality of heating devices according to the number of the heating devices, so as to control the target heating device to operate at the operating power.

[0095] Specifically, after determining the heating strategy, the rated power corresponding to each heating device 7 is obtained, and among the multiple heating devices 7, the heating device 7 that meets the number of heating devices is randomly obtained as the backup heating device, and the sum of the rated powers of the backup heating devices is obtained.

[0096] Furthermore, if the sum is greater than the working power, the backup heating device is used as the target heating device. If it is not satisfied, a new backup heating device is marked among the heating devices other than the current backup heating device, and a previous backup heating device is cancelled to update the backup heating device until the sum of the rated powers of the backup heating devices is greater than the working power.

[0097] Specifically, when the control unit 1 detects that the gas temperature is lower than the preset temperature, it controls the first airflow valve 6 to move to the first target opening, and the second airflow valve 8 to move to the second target opening, so as to open the second gas passage 3, so as to control a small part or no exhaust gas to enter the first gas passage 2 through the first airflow valve 6 and the second airflow valve 8, and most of the exhaust gas enters the target heating device 7 in the second gas passage 3 for heating, so as to ensure that the SCR nitrogen oxide removal reaction in the post-treatment passage 4 meets the operating temperature based on the exhaust gas temperature environment after heating.

[0098] The embodiment of the present application provides a diesel engine aftertreatment system, which transmits the pre-stage SCR temperature obtained by the temperature sensor to the control unit, and then the control unit controls the opening of the first airflow valve set at the entrance of the first gas passage and the second gas passage according to the pre-stage SCR temperature. When it is not necessary to heat the exhaust gas through the electric heating device, the control unit adjusts the amount of exhaust gas entering the first gas passage and the second gas passage by controlling the opening of the first airflow valve to close the amount of gas passing through the electric heating device in the second gas passage, thereby avoiding wasting part of the power of the electric heating device and the heat of the exhaust gas, and at the same time avoiding the problem of carbon accumulation on the surface of the electric heating device when the exhaust gas passes through the electric heating device for a long time, resulting in a reduction in the rated power, thereby improving the reliability and durability of the overall aftertreatment system.

[0099] An embodiment of the present application also provides a vehicle, comprising the above-mentioned diesel engine after-treatment system.

[0100] Finally, it should be noted that those skilled in the art will readily conceive of other embodiments of the present invention after considering the specification and practicing the invention disclosed herein. The present invention is intended to cover any variations, uses or adaptations of the present invention, which follow the general principles of the present invention and include common knowledge or customary technical means in the art not disclosed by the present invention, are not limited to the precise structure described above and shown in the drawings, and may be modified and changed in various ways without departing from the scope thereof. The scope of the present invention is limited only by the appended claims.

Claims

1. A diesel engine aftertreatment system, characterized in that: include: A control unit, a first gas passage, a second gas passage, a post-treatment passage, and a temperature sensor disposed at a front-stage selective catalytic reducer SCR in the post-treatment passage, wherein the first gas passage and the second gas passage are two parallel passages connected at an inlet and an outlet, a first gas flow valve is disposed at the inlet, and the outlet is connected to the post-treatment passage; A heating device is provided on the second gas passage, and the first airflow valve is communicatively connected to the control unit. The control unit is used to control the first airflow valve according to the relationship between the previous SCR temperature sent by the temperature sensor and the preset temperature to adjust the gas passing through the first gas passage and the second gas passage.

2. The diesel engine aftertreatment system according to claim 1, characterized in that: The heating device is coated with an oxidizing catalyst for oxidizing hydrocarbon substances attached to the surface of the heating device.

3. The diesel engine aftertreatment system according to claim 1, characterized in that: The heating device is communicatively connected to the control unit, and the control unit is further used to control the heating device to work when the second gas passage is opened, and to control the heating device to stop working when the second gas passage is closed.

4. The diesel engine aftertreatment system according to claim 1, characterized in that: A second air flow valve is disposed at the outlet, and the second air flow valve is communicatively connected to the control unit, and the control unit is used to keep the states of the first air flow valve and the second air flow valve consistent.

5. The diesel engine aftertreatment system according to claim 1, characterized in that: The post-treatment passage includes: the front-stage SCR, the oxidation catalytic converter DOC, the particulate trap DPF and the rear-stage SCR which are arranged in sequence.

6. The diesel engine aftertreatment system according to claim 1, characterized in that: The first gas passage is provided with a silencer module and / or a gas mixing module.

7. A vehicle, characterized in that: include: A diesel engine aftertreatment system according to any one of claims 1 to 6.

8. A control method for a diesel engine aftertreatment system, characterized in that: The method applied to the diesel engine aftertreatment system according to any one of claims 1 to 6 comprises: The control unit receives the front-stage SCR temperature sent by the temperature sensor, and compares the front-stage SCR temperature with a preset temperature stored locally in the control unit; The control unit controls the first gas flow valve according to the magnitude relationship between the front-stage SCR temperature and the preset temperature to adjust the amount of gas passing through the first gas passage and the second gas passage.

9. The method according to claim 8, characterized in that The controlling the first air flow valve according to the magnitude relationship between the temperature of the front-stage SCR and a preset temperature comprises: Calculating a first temperature difference between the front-stage SCR temperature and the preset temperature; determining a target opening of the first gas flow valve toward the first gas passage according to the first temperature difference, wherein the first temperature difference is positively correlated with the target opening; The first air flow valve is controlled according to the target opening.

10. The method according to claim 9, characterized in that A second air flow valve is disposed at the outlet, and the second air flow valve is communicatively connected to the control unit. The method further comprises: The control unit controls the second air flow valve according to the target opening degree.

11. The method according to any one of claims 8 to 10, characterized in that The heating device is communicatively connected to the control unit, and the method further comprises: The control unit controls the heating device to operate when the second gas passage is opened, and controls the heating device to stop operating when the second gas passage is closed.

12. The method according to claim 11, characterized in that The heating device includes a plurality of heating devices, and the control unit controls the heating device to work when the second gas passage is opened, including: The control unit determines a second temperature difference between the preset temperature and the front-stage SCR temperature; The control unit determines a heating strategy according to the second temperature difference, wherein the heating strategy includes the number of heating devices and the working power, and the number of heating devices, the working power and the second temperature difference are positively correlated; The control unit selects a target heating device from the plurality of heating devices according to the number of the heating devices, so as to control the target heating device to operate at the operating power.

13. The method according to any one of claims 8 to 10, characterized in that Also includes: The control unit acquires state information, the state information including at least one of the following: exhaust flow, exhaust temperature, engine speed, and engine torque; The control unit obtains the preset temperature corresponding to the state information from a preset mapping list locally stored in the control unit, wherein the preset mapping list includes a relationship between the state information and the preset temperature.

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