Diesel engine aftertreatment system, vehicle, and control method

Abstract

The application provides a diesel engine aftertreatment system, a vehicle and a control method. The system transmits the front SCR temperature obtained by a temperature sensor to a control unit, and then the control unit controls the opening degree of a first airflow valve arranged at the entrances of first and second gas passages according to the front SCR temperature. When the exhaust gas does not need to be heated by an electric heating device, the control unit controls the opening degree of the first airflow valve to adjust the gas amount of the exhaust gas entering the first and second gas passages, so as to close the gas amount passing through the electric heating device in the second gas passage, thereby avoiding the waste of part of the power of the electric heating device and the exhaust gas heat, and avoiding the problem that the carbon deposited on the surface of the electric heating device reduces the rated power when the exhaust gas passes through the electric heating device for a long time, and further improving the reliability and durability of the overall aftertreatment system.

Description

TECHNICAL FIELD

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

[0002] To meet the current requirements for environmental protection and exhaust emission requirements, the existing scheme usually takes the nitrogen and oxygen removal system with a selective catalytic reducer as the core as the main vehicle exhaust treatment scheme to be widely used in various vehicles at present.

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

[0004] However, since the electric heating device itself is made of metal material, the heat dissipation efficiency is high, not only the heat dissipation itself will waste part of the power, but also the carbon deposition on the surface of the electric heating device will cause the rated power to decrease, thereby causing the reliability and durability of the nitrogen and oxygen removal system to decrease. SUMMARY

[0005] The diesel engine aftertreatment system, the vehicle and the control method provided by the embodiments of the present application are used to solve the defects of power waste and rated power decrease caused by carbon deposition due to the electric heating device made of metal material in the existing treatment scheme, thereby causing the poor reliability and durability of the nitrogen and oxygen removal system.

[0006] In a first aspect, the embodiments of the present application provide a diesel engine aftertreatment system, comprising:

[0007] a control unit, a first gas passage, a second gas passage, an aftertreatment passage and a temperature sensor arranged at a front-stage selective catalytic reducer SCR in the aftertreatment passage, the first gas passage and the second gas passage being two parallel passages communicated at an inlet and communicated at an outlet, a first airflow valve being arranged at the inlet, the outlet being connected to the aftertreatment passage;

[0008] a heating device being arranged on the second gas passage, the first airflow valve being communicatively connected to the control unit, the control unit being configured to control the first airflow valve according to the size relationship between the front-stage SCR temperature sent by the temperature sensor and a preset temperature, so as to adjust the gas passing through the first gas passage and the second gas passage.

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

[0010] In one possible implementation, the heating device is communicatively connected to the control unit, which is further configured 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 one possible implementation, a second airflow valve is provided at the outlet, the second airflow valve being communicatively connected to the control unit, the control unit being used to keep the states of the first airflow valve and the second airflow valve consistent.

[0012] In one possible implementation, the post-processing pathway includes, in sequence: the pre-stage SCR, the oxidation catalytic converter (DOC), the particulate filter (DPF), and the post-stage SCR.

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

[0014] Secondly, embodiments of this application provide a vehicle including the aforementioned diesel engine aftertreatment system.

[0015] Thirdly, embodiments of this application provide a control method for a diesel engine aftertreatment system, applied to the aforementioned diesel engine aftertreatment system, comprising:

[0016] The control unit receives the 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.

[0017] The control unit controls the first airflow valve according to the relationship between the pre-stage SCR temperature and the preset temperature, so as to adjust the amount of gas passing through the first gas passage and the second gas passage.

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

[0019] The target opening degree of the first airflow valve toward the first gas passage is determined based on the first temperature difference, and the first temperature difference is positively correlated with the target opening degree.

[0020] Control the first airflow valve according to the target opening degree.

[0021] In one possible implementation, a second airflow valve is provided at the outlet, the second airflow valve being communicatively connected to the control unit, and the system further includes:

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

[0023] In one 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 one possible implementation, the heating device includes multiple components, and the control unit controls the heating device to operate when the second gas passage is opened, including:

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

[0026] The control unit determines a heating strategy based on the second temperature difference. The heating strategy includes the number of heating devices and the operating power, and the number of heating devices, the operating 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 heating devices, and controls the target heating device to operate at the working power.

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

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

[0030] This application provides a diesel engine aftertreatment system, vehicle, and control method. After transmitting the temperature of the pre-stage SCR (Selective Catalytic Reduction) system obtained by a temperature sensor to a control unit, the control unit controls the opening degree of a first airflow valve located at the inlet of the first and second gas passages based on the pre-stage SCR temperature. When it is not necessary to heat the exhaust gas through an electric heating device, the control unit adjusts the amount of exhaust gas entering the first and second gas passages by controlling the opening degree of the first airflow valve. This closes the amount of gas passing through the electric heating device in the second gas passage, thereby avoiding the waste of some power from the electric heating device and the heat from the exhaust gas. It also avoids the problem of carbon buildup on the surface of the electric heating device due to long-term exhaust gas passing through it, which leads to a reduction in rated power. This improves the overall reliability and durability of the aftertreatment system. Attached Figure Description

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

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

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

[0034] Figure 3 Flowchart of the control method for the diesel engine aftertreatment system provided in this application Figure One ;

[0035] Figure 4 Flowchart of the control method for the diesel engine aftertreatment system provided in this application Figure Two .

[0036] Figure label:

[0037] 1-Control unit;

[0038] 2-First gas passage; 201-Silencer module; 202-Gas mixing module;

[0039] 3-Second gas passage;

[0040] 4-Post-treatment pathway; 401-Pre-stage SCR; 402-Oxidation catalytic converter (DOC); 403-DPF particulate filter; 404-Post-stage SCR;

[0041] 5-Temperature sensor; 6-First airflow valve; 7-Heating device; 8-Second airflow valve.

[0042] The accompanying drawings illustrate specific embodiments of this application, which will be described in more detail below. These drawings and descriptions are not intended to limit the scope of the concept in any way, but rather to illustrate the concept of this application to those skilled in the art through reference to particular embodiments. Detailed Implementation

[0043] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numbers in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application. Rather, they are merely examples of apparatuses and methods consistent with some aspects of this application as detailed in the appended claims.

[0044] 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, data stored, data displayed, 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. Furthermore, the collection, use and processing of related data must comply with relevant laws, regulations and standards, and corresponding operation entry points are provided for users to choose to authorize or refuse.

[0045] It should be noted that in the embodiments of this application, certain software, components, models and other existing solutions in the industry may be mentioned. These should be regarded as exemplary and are only intended to illustrate the feasibility of implementing the technical solution of this application. However, it does not mean that the applicant has used or necessarily used the solution.

[0046] With increasing societal demands for environmental protection, corresponding regulations on vehicle exhaust emissions are also becoming more stringent. Therefore, current vehicle exhaust treatment systems are no longer sufficient to meet these increasingly stringent regulations. For example, current diesel engine aftertreatment systems typically consist of DOC (Diesel Oxidation Catalyst) + DPF (Diesel Particulate Filter) + SCR (Selective Catalytic Reduction).

[0047] To meet increasingly stringent vehicle emissions regulations, existing solutions typically employ a dual-injection SCR aftertreatment system to treat vehicle exhaust. This dual-injection SCR aftertreatment system includes a pre-stage SCR (Selective Catalytic Reduction) + DOC (Diesel Oxidation Catalyst) + DPF (Diesel Particulate Filter) + post-stage SCR.

[0048] However, the nitrogen and oxygen removal reaction in the dual-injection SCR aftertreatment system is limited by the ambient temperature. When the operating temperature is in the low-temperature range, such as below 220 degrees Celsius, the reaction efficiency is low, which in turn reduces the overall efficiency of the system.

[0049] Therefore, to improve the SCR reaction efficiency under low-temperature conditions such as cold starts, existing treatment solutions typically add an electric heating device before the catalytic converter to increase exhaust temperature. However, electric heating devices are mostly made of metal, which has high heat dissipation efficiency. This not only wastes some power and exhaust heat during heat dissipation, but also easily leads to carbon buildup on the surface, resulting in a reduction in rated power, thereby reducing the reliability and durability of the overall aftertreatment system.

[0050] In view of this, this application provides a diesel engine aftertreatment system. After transmitting the pre-stage SCR temperature obtained by a temperature sensor to a control unit, the control unit controls the opening degree of the first airflow valve at the inlet of the first and second gas passages based on the pre-stage SCR temperature. When it is not necessary to heat the exhaust gas through an electric heating device, the control unit adjusts the amount of exhaust gas entering the first and second gas passages by controlling the opening degree of the first airflow valve. This closes the amount of gas passing through the electric heating device in the second gas passage, thereby avoiding the waste of some power from the electric heating device and the heat from the exhaust gas. It also avoids the problem of carbon buildup on the surface of the electric heating device due to long-term passage of exhaust gas, which leads to a reduction in rated power. This improves the overall reliability and durability of the aftertreatment system.

[0051] The technical solution of this application and how the technical solution of this application solves the above-mentioned technical problems are described in detail below with specific embodiments. These specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described again in some embodiments. The embodiments of this application will now be described with reference to the accompanying drawings.

[0052] Figure 1 Schematic diagram of the diesel engine aftertreatment system provided in this application Figure One ,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 installed at the front selective catalytic reduction (SCR) in the aftertreatment passage 4.

[0053] The first gas passage 2 and the second gas passage 3 are two parallel passages connected at the inlet and at the outlet. A first airflow valve 6 is provided at the inlet, and the outlet is connected to the post-treatment passage 4.

[0054] At least one heating device 7 is provided on the second gas passage 3. The first gas flow valve 6 is communicatively connected to the control unit 1. The control unit 1 is used to control the first gas flow valve 6 according to the relationship between the pre-stage SCR temperature sent by the temperature sensor 5 and the preset temperature, so as to adjust the gas passing through the first gas passage 2 and the second gas passage 3.

[0055] Furthermore, the post-treatment passage 4 includes, in sequence: a pre-stage SCR 401, an oxidation catalytic converter DOC 402, a particulate filter DPF 403, and a post-stage SCR 404, wherein the injection devices corresponding to the pre-stage SCR 401 and the post-stage SCR 404 are controlled to operate by the control unit 1.

[0056] Specifically, when the vehicle is cold-started, the exhaust gas produced is relatively low. After entering the diesel engine aftertreatment system, as it passes through the first gas passage 2 or the second gas passage 3 into the aftertreatment passage 4, the temperature sensor 5 detects the gas temperature and sends the detected temperature to the control unit 1. When the control unit 1 detects that the gas temperature is lower than a preset temperature, it controls the first airflow valve 6 to open to the corresponding degree, opening the second gas passage 3. This allows the exhaust gas to enter the heating device 7 in the second gas passage 3 for heating, thereby ensuring that the pre-stage SCR 401 and post-stage SCR 404 in the aftertreatment passage 4 meet the operating temperature for nitrogen and oxygen removal reactions based on the heated exhaust gas temperature environment, thus avoiding low reaction efficiency.

[0057] 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 operate to the corresponding opening degree, opening the first gas passage 2. This allows the exhaust gas to enter the first gas passage 2 through the first airflow valve 6, avoiding heating the gas through the heating device 7. Since the gas temperature is higher than the preset temperature at this time, it also meets the operating temperature requirement for the SCR nitrogen and oxygen removal reaction in the post-treatment passage 4. This reduces the reduction in rated power caused by carbon buildup on the surface of the heating device 7 due to the exhaust gas passing through it for a long time.

[0058] This application provides a diesel engine aftertreatment system. After transmitting the pre-stage SCR temperature obtained by a temperature sensor to a control unit, the control unit controls the opening of a first airflow valve at the inlet of the first and second gas passages based on the pre-stage SCR temperature. When it is not necessary to heat the exhaust gas through an electric heating device, the control unit adjusts the amount of exhaust gas entering the first and second gas passages by controlling the opening of the first airflow valve. This closes the amount of gas passing through the electric heating device in the second gas passage, thus avoiding wasting some of the power of the electric heating device and the heat from the exhaust gas. It also avoids the problem of carbon buildup on the surface of the electric heating device due to long-term exhaust gas passing through it, which leads to a reduction in rated power. Therefore, the overall reliability and durability of the aftertreatment system are improved.

[0059] Figure 2 Schematic diagram of the diesel engine aftertreatment system provided in this application Figure Two ,like Figure 2As shown, the heating device 7 is communicatively connected to the control unit 1. The control unit 1 is also 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.

[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 to operate to the corresponding opening degree, opens the second gas passage 3, and simultaneously controls the heating device 7 to work, 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.

[0061] When the control unit 1 detects that the gas temperature is higher than the preset temperature, it controls the first airflow valve 6 to operate to the corresponding opening degree, opening the first gas passage 2, and at the same time controls the heating device 7 to stop working. This avoids heating the gas through the heating device 7, saves the heating device 7 from working for a long time, reduces the heat lost by the engine exhaust gas to heat or keep the heating device 7 warm, thereby reducing the power consumed by turning on the electric heating to compensate for the power loss of the electric heating itself, reducing engine fuel consumption, and improving product economy.

[0062] Furthermore, the heating device 7 is coated with an oxidizing catalyst to oxidize hydrocarbons and particulate matter adhering to the surface of the heating device.

[0063] 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 simultaneously controls the heating device 7 to work. When the exhaust gas enters the heating device 7 in the second gas passage 3, the nitrogen oxides in the exhaust gas can also be treated and reduced in advance by the SCR catalyst coated on the heating device 7, so as to reduce the reaction burden of each stage of SCR in the after-treatment passage 4.

[0064] Furthermore, a second airflow valve 8 is provided at the outlet, which is communicatively connected to the control unit 1. The control unit 1 is used to keep the states of the first airflow valve 6 and the second airflow valve 8 consistent.

[0065] 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 operate to their respective opening degrees, opening the second gas passage 3, and simultaneously controlling the heating device 7 to work. After the exhaust gas is heated by the heating device 7 in the second gas passage 3 through the first airflow valve 6, it enters the post-processing passage 4 under the guidance of the second airflow valve 8, so as to avoid the airflow being reversed and transmitted into the first gas passage 2 when the back pressure in the post-processing passage 4 is large.

[0066] When the control unit 1 detects that the gas temperature is higher than the preset temperature, it controls the first airflow valve 6 and the second airflow valve 8 to operate to their respective opening degrees, opening the first gas passage 2, and under the guidance of the second airflow valve 8, the gas enters the post-processing passage 4, so as to avoid the airflow being reversed and transmitted into the second gas passage 3 when the back pressure of the post-processing passage 4 is large.

[0067] Furthermore, a silencing module 201 and / or a gas mixing module 202 are provided on the first gas passage 2 to eliminate the noise of exhaust gas emissions through the silencing module 201.

[0068] This application provides a diesel engine aftertreatment system. After transmitting the pre-stage SCR temperature obtained by a temperature sensor to a control unit, the control unit controls the opening of a first airflow valve at the inlet of the first and second gas passages based on the pre-stage SCR temperature. When it is not necessary to heat the exhaust gas through an electric heating device, the control unit adjusts the amount of exhaust gas entering the first and second gas passages by controlling the opening of the first airflow valve. This closes the amount of gas passing through the electric heating device in the second gas passage, thus avoiding wasting some of the power of the electric heating device and the heat from the exhaust gas. It also avoids the problem of carbon buildup on the surface of the electric heating device due to long-term exhaust gas passing through it, which leads to a reduction in rated power. Therefore, the overall reliability and durability of the aftertreatment system are improved.

[0069] Figure 3 Flowchart of the control method for the diesel engine aftertreatment system provided in this application Figure One ,like Figure 2 As shown, in this embodiment... Figure 1 and Figure 2 Based on the embodiments, the control method of the diesel engine aftertreatment system is described in detail, and the method includes:

[0070] S101. The control unit receives the pre-stage SCR temperature sent by the temperature sensor and compares the pre-stage SCR temperature with the preset temperature stored locally in the control unit.

[0071] Specifically, when the vehicle starts, the exhaust gas produced by the vehicle enters the aftertreatment passage 4 through the first gas passage 2 or the second gas passage 3. The temperature of the gas, i.e., the temperature of the pre-stage SCR, is collected by the temperature sensor 5 and sent to the control unit 1. Of course, the control unit 1 can also obtain status information including exhaust flow rate, exhaust temperature (i.e., the temperature of the pre-stage SCR), engine speed, and engine torque through different sensors.

[0072] Furthermore, the control unit obtains the preset temperature corresponding to the status information from the preset mapping list stored locally in the control unit. The preset mapping list includes the relationship between the status information and the preset temperature.

[0073] S102. The control unit controls the first airflow valve according to the relationship between the pre-stage SCR temperature and the preset temperature, so as to adjust the amount of gas passing through the first gas passage and the second gas passage.

[0074] Specifically, after the control unit 1 obtains the corresponding preset temperature based on the temperature of the pre-stage SCR, it detects whether the temperature of the pre-stage SCR is greater than the preset temperature. If so, the control unit 1 controls the first airflow valve 6 to operate to the corresponding opening degree to open the first gas passage 2 and close the second gas passage 3, so that the gas enters each catalyst in the aftertreatment passage 4 through the first gas passage 2 for exhaust gas treatment.

[0075] Furthermore, if not, the control unit 1 controls the first gas flow valve 6 to operate to the corresponding opening degree 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 each catalyst in the aftertreatment passage 4 for exhaust gas treatment.

[0076] This application provides a diesel engine aftertreatment system. After transmitting the pre-stage SCR temperature obtained by a temperature sensor to a control unit, the control unit controls the opening of a first airflow valve at the inlet of the first and second gas passages based on the pre-stage SCR temperature. When it is not necessary to heat the exhaust gas through an electric heating device, the control unit adjusts the amount of exhaust gas entering the first and second gas passages by controlling the opening of the first airflow valve. This closes the amount of gas passing through the electric heating device in the second gas passage, thus avoiding wasting some of the power of the electric heating device and the heat from the exhaust gas. It also avoids the problem of carbon buildup on the surface of the electric heating device due to long-term exhaust gas passing through it, which leads to a reduction in rated power. Therefore, the overall reliability and durability of the aftertreatment system are improved.

[0077] Figure 4 Flowchart of the control method for the diesel engine aftertreatment system provided in this application Figure Two ,like Figure 4 As shown, in this embodiment... Figure 3 Based on the embodiments, the control method of the diesel engine aftertreatment system is described in detail, and the method includes:

[0078] S201. The control unit receives the pre-stage SCR temperature sent by the temperature sensor and compares the pre-stage SCR temperature with the preset temperature stored locally in the control unit.

[0079] Specifically, once the vehicle starts, it acquires status information through vehicle sensors and retrieves the corresponding preset temperature from a preset mapping list based on the status information. These vehicle sensors include a flow sensor, a temperature sensor, a speedometer, and a torque sensor.

[0080] Furthermore, the exhaust gas flow rate is obtained through a flow sensor, the exhaust gas temperature (i.e., the temperature of the pre-stage SCR) is obtained through a temperature sensor, the engine speed is obtained through a speedometer, and the vehicle's output torque is obtained through a torque sensor. The exhaust gas flow rate, exhaust gas temperature (after passing through the pre-stage SCR), vehicle speed, and output torque are used as status information.

[0081] Furthermore, regarding the relationship between the status information and the preset temperature in the preset mapping list, the exhaust flow rate, exhaust temperature, engine speed, and output torque in the status information are positively correlated with the preset temperature.

[0082] S202. Calculate the first temperature difference between the pre-stage SCR temperature and the preset temperature.

[0083] Specifically, after the control unit 1 obtains the temperature of the preceding SCR, if the temperature of the preceding SCR is greater than or equal to the preset temperature, the difference between the temperature of the preceding SCR and the preset temperature is obtained as the first temperature difference.

[0084] S203. Determine the target opening degree of the first airflow valve toward the first gas passage based on the first temperature difference.

[0085] Specifically, after obtaining the first temperature difference, the same temperature difference value as the first temperature difference is obtained from the first opening database of the control unit 1, and the corresponding opening value is determined based on the same temperature difference value as the target opening value corresponding to the first temperature difference.

[0086] The first opening database is used to indicate the opening degree of the first airflow valve 6 and the second airflow valve 8 corresponding to the first temperature difference when gas heating is not required. The first opening database has multiple sets of different temperature difference values ​​and opening values ​​stored in advance, wherein the temperature difference value and the opening value are positively correlated.

[0087] 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 both 100, the first gas passage 2 is fully opened and the second gas passage 3 is fully closed.

[0088] S204. Control the first airflow valve according to the target opening degree, and control the second airflow valve according to the target opening degree.

[0089] Specifically, after the control unit 1 obtains the target opening degree based on the first temperature difference, the control unit 1 controls the first airflow valve 6 to operate to the first target opening degree, and the control unit 1 controls the second airflow valve 8 to operate to the second target opening degree.

[0090] Furthermore, by controlling the opening of the first airflow valve 6 and the second airflow valve 8, the first gas passage 2 is opened, so that most or all of the gas passes through the first gas passage 2, while a small portion or no gas passes through the second gas passage 3. Under the guidance of the second airflow valve 8, the gas enters the post-processing passage 4, so as to avoid the gas flow from being reversed and entering the second gas passage 3 when the back pressure of the post-processing passage 4 is large.

[0091] S205, The control unit determines a second temperature difference between the preset temperature and the pre-stage SCR temperature.

[0092] Specifically, if the temperature of the preceding SCR is lower than the preset temperature, the difference between the preset temperature and the temperature of the preceding 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.

[0093] Furthermore, based on the second temperature difference, a temperature difference value identical to the second temperature difference is obtained from the second opening database of the control unit 1, and the corresponding opening value is determined based on the identical temperature difference value as the target opening value corresponding to the second temperature difference.

[0094] The second opening database is used to indicate the opening degree 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 has multiple sets of temperature differences and opening values ​​pre-associated and stored. At this time, the temperature difference value and the opening value are negatively correlated.

[0095] The opening of the first gas flow valve 6 and the second gas flow valve 8 are controlled according to the first target opening and the second target opening respectively. When the first target opening and the second target opening are zero, the second gas passage 3 is fully opened and the first gas passage 2 is fully closed, so that the gas is heated only through the heating device 7 in the second gas passage 3 and does not enter the first gas passage 2.

[0096] S206. The control unit determines the heating strategy based on the second temperature difference.

[0097] Specifically, after obtaining the second temperature difference, the same temperature difference value is obtained from the strategy database of the control unit 1 based on the second temperature difference, and the corresponding strategy information is determined based on the same temperature difference value as the heating strategy. Multiple heating devices 7 are provided in the second gas passage 3.

[0098] The strategy database pre-stores multiple sets of different temperature difference values ​​and strategy information. The strategy information is used to indicate the working power and number of heating devices required to reach the working temperature. The heating strategy includes the number of heating devices and the working power. The number of heating devices, the working power, and the second temperature difference are positively correlated.

[0099] S207. The control unit selects a target heating device from the plurality of heating devices according to the number of heating devices, and controls the target heating device to operate at the working power.

[0100] Specifically, after determining the heating strategy, the rated power of each heating device 7 is obtained. Among the multiple heating devices 7, heating devices 7 that meet the required number of heating devices are randomly selected as backup heating devices, and the sum of the rated power of the backup heating devices is obtained.

[0101] Furthermore, if the sum of the values ​​is greater than the operating power, the backup heating device is designated as the target heating device. If the condition is not met, 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 canceled to update the backup heating device, until the sum of the rated power of the backup heating devices is greater than the operating power.

[0102] 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 degree and the second airflow valve 8 to move to the second target opening degree, so as to open the second gas passage 3. This allows the first airflow valve 6 and the second airflow valve 8 to control a small portion or no exhaust gas to enter the first gas passage 2, while most of the exhaust gas enters the target heating device 7 in the second gas passage 3 for heating. Based on the temperature environment of the heated exhaust gas, the SCR nitrogen and oxygen removal reaction in the post-treatment passage 4 is guaranteed to meet the working temperature.

[0103] This application provides a diesel engine aftertreatment system. After transmitting the pre-stage SCR temperature obtained by a temperature sensor to a control unit, the control unit controls the opening of a first airflow valve at the inlet of the first and second gas passages based on the pre-stage SCR temperature. When it is not necessary to heat the exhaust gas through an electric heating device, the control unit adjusts the amount of exhaust gas entering the first and second gas passages by controlling the opening of the first airflow valve. This closes the amount of gas passing through the electric heating device in the second gas passage, thus avoiding wasting some of the power of the electric heating device and the heat from the exhaust gas. It also avoids the problem of carbon buildup on the surface of the electric heating device due to long-term exhaust gas passing through it, which leads to a reduction in rated power. Therefore, the overall reliability and durability of the aftertreatment system are improved.

[0104] This application also provides a vehicle including the above-described diesel engine aftertreatment system.

[0105] Finally, it should be noted that other embodiments of the invention will readily occur to those skilled in the art upon consideration of the specification and practice of the invention disclosed herein. This invention is intended to cover any variations, uses, or adaptations of the invention that follow the general principles of the invention and include common knowledge or customary techniques in the art not disclosed herein, and is not limited to the precise structures described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of the invention is limited only by the appended claims.

Claims

1. A diesel engine aftertreatment system, characterized in that, include: The system includes a control unit, a first gas passage, a second gas passage, a post-treatment passage, and a temperature sensor located at the upstream selective catalytic reduction (SCR) in the post-treatment passage. The first gas passage and the second gas passage are two parallel passages connected at the inlet and at the outlet. A first gas flow valve is provided at the inlet, and the outlet is connected to the post-treatment passage. A heating device is provided in the second gas passage. The first gas flow valve is communicatively connected to the control unit. The control unit is used to control the first gas flow valve according to the relationship between the pre-stage SCR temperature sent by the temperature sensor and the preset temperature, so as to adjust the gas passing through the first gas passage and the second gas passage. A second gas flow valve is provided at the outlet. The second gas flow valve is communicatively connected to the control unit. The control unit is used to keep the opening degree of the first gas flow valve and the second gas flow valve consistent. The heating equipment includes multiple devices; When the second gas passage is opened, the control unit determines a second temperature difference between the preset temperature and the pre-stage SCR temperature. The control unit determines a heating strategy based on the second temperature difference. The heating strategy includes the number of heating devices and the operating power, and the number of heating devices, the operating 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 heating devices, and controls the target heating device to operate at the working power; The first gas passage is equipped with a noise reduction module and / or a gas mixing module; The preset temperature is the preset temperature corresponding to the status information obtained by the control unit from the preset mapping list stored locally by the control unit. The preset mapping list includes the relationship between the status information and the preset temperature.

2. The diesel engine aftertreatment system according to claim 1, characterized in that, The heating device is coated with an oxidizing catalyst for oxidizing hydrocarbons adhering 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, which is further configured 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.

4. The diesel engine aftertreatment system according to claim 1, characterized in that, The post-processing pathway includes, in sequence: the pre-stage SCR, the oxidation catalytic converter (DOC), the particulate filter (DPF), and the post-stage SCR.

5. A vehicle, characterized in that, include: The diesel engine aftertreatment system according to any one of claims 1 to 4.

6. 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 4, comprises: The control unit receives the 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. The control unit controls the first airflow valve according to the relationship between the pre-stage SCR temperature and the preset temperature, so as to adjust the amount of gas passing through the first gas passage and the second gas passage; The heating device is communicatively connected to the control unit, and the method further includes: The heating equipment includes multiple devices; When the second gas passage is opened, the control unit determines a second temperature difference between the preset temperature and the pre-stage SCR temperature. The control unit determines a heating strategy based on the second temperature difference. The heating strategy includes the number of heating devices and the operating power, and the number of heating devices, the operating 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 heating devices, and controls the target heating device to operate at the working power; A second airflow valve is provided at the outlet, and the second airflow valve is communicatively connected to the control unit. The method further includes: The control unit controls the second airflow valve according to the target opening degree; The control unit acquires status information; The control unit obtains the preset temperature corresponding to the status information from a preset mapping list stored locally on the control unit. The preset mapping list includes the relationship between the status information and the preset temperature.

7. The method according to claim 6, characterized in that, The step of controlling the first airflow valve based on the relationship between the pre-stage SCR temperature and the preset temperature includes: Calculate the first temperature difference between the pre-stage SCR temperature and the preset temperature; The target opening degree of the first airflow valve toward the first gas passage is determined based on the first temperature difference, and the first temperature difference is positively correlated with the target opening degree. Control the first airflow valve according to the target opening degree.

8. The method according to any one of claims 6 to 7, characterized in that, The heating device is communicatively connected to the control unit, and the method further includes: 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.

9. The method according to any one of claims 6 to 7, characterized in that, The status information includes at least one of the following: exhaust flow rate, exhaust temperature, engine speed, and engine torque.

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