EHC heating control method and system based on HC accumulation effect

Abstract

The present invention proposes an EHC heating control method and system based on the HC accumulation effect. This method first determines whether the aftertreatment system requires a temperature increase. If so, it records the HC emission mass flow rate and calculates the actual HC accumulation / removal rate on the DOC in real time. The accumulated HC mass on the DOC is then integrated and the cumulative heat release of this HC is further calculated. A target temperature increase time is determined, the maximum EHC heat release during this time is calculated, and the total target energy required to raise the temperature to the lower limit of the SCR carrier's efficient temperature window is calculated. When the sum of the HC oxidation heat release and the EHC heat release during the target temperature increase time exceeds the total target energy, the EHC heating release condition is met. Closed-loop control is then implemented. If the SCR carrier temperature is detected to have exceeded the monitoring value, the EHC heating function is deactivated, and the cold start heating requirement of the aftertreatment system is met. This invention addresses the low EHC heating power and limited temperature increase capacity of conventional low-pressure systems.

Description

Technical Field

[0001] The present invention relates to the technical field of rapid temperature increase of a diesel engine aftertreatment system, and in particular to an EHC heating control method and system based on HC accumulation effect. Background Art

[0002] The engine exhaust contains nitrogen oxides (NO x ) This harmful substance, NO x It is the reaction product of N2 and O2 in the air sucked into the cylinder by the engine at high temperature. Its main components are NO and NO2. x The emission of pollutants is restricted and different levels of limit values are stipulated.

[0003] Urea selective catalytic reduction technology (Urea-SCR technology for short) is a technology that controls NO x The main technology for emission reduction is the most common form of this technology: using urea aqueous solution to decompose ammonia (NH3), and under the action of SCR catalyst, ammonia and NO x Selective catalytic reduction reaction occurs, generating nitrogen and water which are then discharged into the atmosphere. By injecting different amounts of urea into the exhaust of the diesel engine, NO x Effectively control emissions.

[0004] When the temperature is lower than 187℃, the hydrolysis and thermal decomposition reactions of urea cannot fully occur. At the same time, the SCR reaction cannot fully occur when the temperature is lower than 250℃. Therefore, the NO x The main difficulty in emission control is that the after-treatment system cannot fully play its catalytic conversion effect due to the low temperature. Usually, the following measures are needed to improve the emission control ability during the cold start period: first, quickly shorten the time from cold start to the normal operating temperature of the after-treatment system; second, reduce the engine emission level during the cold start period; third, through (lean NO x Capture) LNT or (passive NO x PNA and other technical means adsorb current emission pollutants when the post-treatment system is not working.

[0005] To quickly shorten the time it takes for a vehicle to reach normal operating temperature from a cold start, an electrically heated catalyst (EHC) is a commonly used technology. However, the heating power provided by conventional vehicles' 12V or 24V power supply systems is relatively limited, often insufficient to quickly heat the aftertreatment system to the target temperature. Furthermore, the electricity used for EHC heating comes from the engine's power generation, limiting energy utilization to below the heat-to-work conversion efficiency. Frequent use of the EHC is highly detrimental to fuel efficiency.

[0006] Another commonly used after-treatment system temperature-raising technology is fuel post-injection. This involves injecting a certain amount of fuel into the cylinder late in combustion, allowing it to enter the diesel oxidation catalyst (DOC) along with the exhaust. The DOC's powerful catalytic activity then reacts with the oxygen in the exhaust, generating heat and raising the exhaust temperature. However, this technology is still limited by the DOC's light-off temperature; if the DOC carrier temperature does not reach this level, the oxidation reaction will be difficult to occur.

[0007] Traditional EHC heating methods often begin simultaneously with engine start-up, reducing the time it takes for the DOC to reach ignition temperature. This prevents sufficient HC accumulation, hindering the effective heat release rate of the EHC and slowing the temperature rise of the aftertreatment system during cold starts. Furthermore, traditional post-injection fuel control strategies fail to assess the DOC's real-time adsorption capacity. Excessive HC cannot be effectively adsorbed by the DOC, leading to high HC emissions. Furthermore, the premature EHC intervention under traditional heating methods often prevents the effective utilization of the DOC's stronger HC adsorption capacity at low temperatures. Summary of the Invention

[0008] Based on this, the purpose of the present invention is to propose an EHC heating control method and system based on the HC accumulation effect, so as to effectively make up for the shortcomings of the traditional low-pressure system EHC heating power and limited temperature raising capacity, and thus provide a NO x Effective control of emissions lays the foundation for temperature.

[0009] In one aspect, the present invention provides an EHC heating control method based on HC accumulation effect, the method comprising:

[0010] S1: Acquire the working state of the post-processing system to determine whether the post-processing system needs to be heated according to the working state of the post-processing system;

[0011] S2: If the after-treatment system needs to increase its temperature, the HC emission mass flow rate after the engine is started is integrated to obtain the HC cumulative mass and HC cumulative heat release on the DOC;

[0012] S3: determining whether the sum of the HC cumulative heat release and the EHC heat release during the target warming time is greater than the total target energy;

[0013] S4: If the sum of the HC cumulative heat release and the EHC heat release during the target heating time is greater than the total target energy, it is determined that the EHC heating function release condition is met, and the EHC heating power is set.

[0014] S5: Recording the SCR substrate temperature and temperature rise rate every first preset time;

[0015] S6: Determine whether the SCR carrier temperature is greater than a first preset temperature threshold, where the first preset temperature threshold is the sum of a high-efficiency temperature window lower limit and a second preset temperature adjustment threshold;

[0016] S7: If the SCR carrier temperature is greater than a first preset temperature threshold, controlling the EHC heating to stop;

[0017] S8: If the SCR carrier temperature is less than or equal to a first preset temperature threshold, determining whether the temperature rise rate is greater than the first preset temperature rise rate threshold;

[0018] S9: If the temperature rise rate is greater than a first preset temperature rise rate threshold, reducing the EHC heating power by a first preset adjustment power threshold, and repeating steps S5 to S6;

[0019] S10: If the temperature rise rate is less than or equal to a first preset temperature rise rate threshold, determining whether the temperature rise rate is greater than a second preset temperature rise rate threshold;

[0020] S11: If the temperature rise rate is greater than the second preset temperature rise rate threshold, increasing the fuel post-injection amount by the first preset fuel post-injection amount threshold, and repeating steps S5 to S6;

[0021] S12: If the temperature rise rate is less than or equal to the second preset temperature rise rate threshold, directly repeat steps S5 to S6 until the SCR carrier temperature is greater than the first preset temperature threshold.

[0022] In summary, according to the above-mentioned EHC heating control method based on the HC accumulation effect, this method can enhance the temperature raising performance of the thermal management control system for the after-treatment system by prompting the DOC to release a large amount of heat by oxidizing the HC stored before reaching the ignition temperature in a short period of time when the EHC heating capacity is limited. This method can help to achieve rapid temperature raising of the after-treatment system, so that the time for the SCR system to reach the start-up temperature is advanced, thereby more effectively controlling the tail pipe NOx during the cold start stage. x Emissions, at the same time, the HC adsorption capacity of DOC under low temperature conditions can be more effectively used to control HC emissions. This method greatly improves the energy utilization rate of the system's chemical energy and electrical energy, and has a significant effect on improving the fuel economy and emission performance of the entire vehicle.

[0023] In a preferred embodiment of the present invention, the step of obtaining the working status of the post-processing system and determining whether the post-processing system needs to be heated according to the working status of the post-processing system includes:

[0024] Acquire a temperature value of a DOC front temperature sensor and a DOC rear temperature sensor, and calculate an average temperature value based on the temperature value of the DOC front temperature sensor and the temperature value of the DOC rear temperature sensor;

[0025] Determining whether the average temperature value is less than the DOC ignition temperature;

[0026] If the average temperature value is less than the DOC light-off temperature, it is determined that there is a need to increase the temperature of the after-treatment system.

[0027] In a preferred embodiment of the present invention, the step of determining whether the sum of the accumulated HC heat release and the EHC heat release during the target warm-up time is greater than the total target energy includes:

[0028] Determining a target heating time and an amount of heat released by the EHC during the target heating time using the EHC heating power, the exhaust mass flow rate, and the DOC carrier temperature;

[0029] The total target energy required to raise the temperature of the SCR substrate to the lower limit of the SCR substrate high-efficiency temperature window is calculated based on the current SCR substrate temperature.

[0030] In a preferred embodiment of the present invention, the step of determining the target heating time and the amount of heat released by the EHC during the target heating time by using the EHC heating power, the exhaust mass flow rate, and the DOC carrier temperature includes:

[0031] The DOC carrier temperature estimation model takes the DOC inlet exhaust temperature, DOC outlet exhaust temperature and exhaust mass flow rate as inputs to calculate the DOC carrier temperature under low temperature conditions;

[0032] The DOC carrier temperature estimation model takes the EHC rated heating power, DOC carrier temperature and exhaust mass flow as inputs, and obtains the target heating time under the current DOC carrier temperature conditions by checking the post-processing target heating time calibration MAP;

[0033] After calculating the actual heating power of the EHC based on the current actual battery voltage signal, the actual heating power of the EHC is multiplied by the target heating time to obtain the amount of heat released by the EHC within the target heating time.

[0034] In a preferred embodiment of the present invention, the step of calculating the total target energy required to raise the temperature of the SCR carrier to the lower limit of the SCR carrier high-efficiency temperature window according to the current SCR carrier temperature includes:

[0035] The SCR inlet exhaust temperature, SCR outlet exhaust temperature, and exhaust mass flow rate measured by the sensor are used as inputs. The current SCR carrier temperature is calculated using the established SCR carrier temperature estimation model. The current SCR carrier temperature is compared with the lower limit of the SCR carrier high-efficiency temperature window, and the energy input required to raise the carrier temperature is calculated based on the carrier specific heat capacity.

[0036] The thermal efficiency of the heat exchange between the SCR carrier and the exhaust gas is calculated based on the thermodynamic process model to obtain the energy required for the exhaust gas at the SCR inlet and the energy required for the exhaust gas at the SCR outlet. The total target energy required to increase the temperature to the lower limit of the carrier's high-efficiency temperature window is calculated based on the current SCR inlet exhaust temperature and the energy required for the exhaust gas at the SCR inlet.

[0037] In a preferred embodiment of the present invention, if there is a need to increase the temperature of the after-treatment system, then after the step of integrating the HC emission mass flow rate after the engine is started to obtain the HC cumulative mass and HC cumulative heat release on the DOC, the following steps are further included:

[0038] The real-time desorption rate and maximum adsorption rate are calculated using the exhaust mass flow rate, the calculated real-time HC storage amount, and the DOC carrier temperature as inputs, and the actual HC accumulation / removal rate is calculated using the maximum adsorption rate and the HC emission mass flow rate.

[0039] When the HC emission mass flow rate is less than the maximum adsorption rate, the HC accumulation / removal rate on the DOC is equal to the HC emission mass flow rate under the current conditions minus the desorption rate under the current conditions.

[0040] In a preferred embodiment of the present invention, the DOC substrate temperature estimation model includes modeling three thermodynamic processes, including convection heat transfer between exhaust and catalyst, heat conduction inside the catalyst, and radiation heat transfer from the catalyst housing to the atmosphere, wherein:

[0041] The convective heat transfer Φ between exhaust gas and catalyst per unit time is calculated according to the following formula P-C :

[0042] Φ P-C =hA H-T (T P -T C )

[0043] Where: h is the heat transfer coefficient of exhaust gas and catalyst convection heat transfer, W / (m 2 K); TP is the exhaust temperature, K; TC is the catalyst temperature, K; A H-T The total surface area of the catalyst that can contact the exhaust gas; ε is used to represent the porosity of the catalyst, Scat is the internal surface area of the catalyst per unit volume of gas that can flow through the catalyst, m 2 / m3 , then A is calculated according to the following formula H-T :

[0044]

[0045] Among them, r C is the catalyst cross-sectional radius, m; L C is the length of the catalyst, m; is the total volume of the catalyst VC; is the total cross-sectional area of the catalyst; is the area where the exhaust is blocked by the catalyst.

[0046] In a preferred embodiment of the present invention, the heat Φ of the catalyst per unit time is calculated according to the following formula: C :

[0047]

[0048] Among them, λ C represents the thermal conductivity of the catalyst carrier, X represents the length of the microelement along the heat transfer direction, r c represents the carrier radius, ε represents the porosity, T C Indicates the carrier temperature.

[0049] In a preferred embodiment of the present invention, the radiation heat transfer Φ of the catalyst housing to the atmosphere is calculated according to the following formula: C-amb :

[0050]

[0051] Among them, A Rad is the radiation area between the catalyst and the outside world, m 2 ; ε Rad is the radiation blackness; σ SB is the gas radiation constant, W / m 2 K 4 ;T amb is the ambient temperature, K.

[0052] Another aspect of the present invention further provides an EHC heating control system based on HC accumulation effect, the system comprising:

[0053] A temperature increase demand monitoring module is used to obtain the working status of the post-processing system to determine whether the post-processing system needs to increase its temperature according to the working status of the post-processing system;

[0054] an integral calculation module, configured to perform an integral calculation on the HC emission mass flow rate after the engine is started if there is a need to increase the temperature of the after-treatment system, to obtain the HC cumulative mass and HC cumulative heat release on the DOC;

[0055] a total target energy monitoring module, configured to determine whether the sum of the accumulated heat release of the HC and the heat release of the EHC during the target warming time is greater than the total target energy;

[0056] a heating power setting module, configured to determine that an EHC heating function release condition is satisfied if the sum of the HC cumulative heat release and the EHC heat release within the target heating time is greater than the total target energy, and to set the EHC heating power;

[0057] A real-time recording module, configured to record the SCR substrate temperature and temperature rise rate at first preset time intervals;

[0058] An SCR carrier temperature monitoring module is configured to determine whether the SCR carrier temperature is greater than a first preset temperature threshold, where the first preset temperature threshold is the sum of a high-efficiency temperature window lower limit and a second preset temperature adjustment threshold;

[0059] an EHC heating stop execution module, configured to control EHC heating to stop if the SCR carrier temperature is greater than a first preset temperature threshold;

[0060] a first temperature rise rate monitoring module, configured to determine whether the temperature rise rate is greater than a first preset temperature rise rate threshold if the SCR carrier temperature is less than or equal to a first preset temperature threshold;

[0061] a heating power regulating module, configured to reduce the EHC heating power by the first preset regulating power threshold if the temperature rise rate is greater than a first preset temperature rise rate threshold, and repeatedly record the SCR substrate temperature and the temperature rise rate;

[0062] a second temperature rise rate monitoring module, configured to determine whether the temperature rise rate is greater than a second preset temperature rise rate threshold if the temperature rise rate is less than or equal to the first preset temperature rise rate threshold;

[0063] If the temperature rise rate is less than or equal to a second preset temperature rise rate threshold, repeatedly recording the SCR carrier temperature and the temperature rise rate until the SCR carrier temperature is greater than a first preset temperature threshold;

[0064] The fuel post-injection amount adjustment module is configured to increase the fuel post-injection amount by the first preset fuel post-injection amount threshold if the temperature rise rate is greater than the second preset temperature rise rate threshold, and repeatedly record the SCR substrate temperature and the temperature rise rate.

[0065] Additional aspects and advantages of the present invention will be set forth in part in the following description and, in part, will be obvious from the following description, or may be learned through embodiments of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0066] Figure 1This is a flow chart of an EHC heating control method based on HC accumulation effect proposed in a first embodiment of the present invention;

[0067] Figure 2 This is a schematic diagram of the hardware environment of the post-processing system;

[0068] Figure 3 This is the workflow diagram for the post-processing heating control strategy;

[0069] Figure 4 This is a flow chart for estimating EHC heat generation within the target heating time;

[0070] Figure 5 Flowchart for estimating the total heat released by oxidation of HC stored on the DOC;

[0071] Figure 6 Flowchart for calculating the total target energy required to raise the SCR substrate temperature to the lower limit of the substrate's high-efficiency temperature window;

[0072] Figure 7 This is the workflow diagram of the closed-loop control strategy for heating power and fuel post-injection quantity during the EHC heating process;

[0073] Figure 8 Schematic diagram of the structure of an EHC heating control system based on HC accumulation effect in the second embodiment of the present invention.

[0074] The following specific embodiments will further illustrate the present invention in conjunction with the above-mentioned drawings. DETAILED DESCRIPTION

[0075] To facilitate understanding of the present invention, the present invention will be described more fully below with reference to the accompanying drawings. The drawings illustrate several embodiments of the present invention. However, the present invention may be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and comprehensive understanding of the present invention.

[0076] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this invention pertains. The terms used in this specification of the present invention are for the purpose of describing specific embodiments only and are not intended to limit the present invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0077] See also Figure 2, which shows a schematic diagram of the hardware environment of the post-treatment system. The post-treatment system corresponding to the preferred embodiment of the present invention is an EHC+SDPF+SCR+ASC solution, matched with a two-stage urea injection system. The exhaust gas undergoes catalytic oxidation by the DOC catalyst on the EHC, oxidizing reducing gases such as HC and CO. At the same time, NO can further react with O2 on the DOC to produce NO2. When the SDPF carrier temperature exceeds the critical temperature for urea injection, the 1# urea nozzle begins to inject urea. The injected urea undergoes thermal decomposition and hydrolysis under the heating of the exhaust gas, generating NH3. NH3 reacts with NO under the action of the SCR catalyst coated on the SDPF. x React quickly to generate N2 and H2O. If the urea injection amount is insufficient, the remaining NO x Will continue to flow downstream. If there is excess urea injection, the remaining NH3 will flow downstream. The downstream SCR acts as a redundant DeNO x The system bears the remaining NO x The 2# urea nozzle supplies the required reducing agent for the conversion work. The SCR system can be arranged away from the SDPF to obtain a larger temperature difference. In this arrangement, if the temperature of the upstream SDPF is too high and the conversion efficiency decreases, the downstream SCR can still achieve excellent DeNO with this temperature difference. x Performance to ensure the overall conversion efficiency of the system. The reductant supply system of the entire after-treatment system uses a urea aqueous solution with a mass concentration of 32.5% as a reductant. The ECU and DCU can be independent hardware structures or combined into a complete control unit. The ECU and DCU collect engine speed, engine fuel injection volume, intake air temperature, intake air pressure, intake air mass flow, EGR valve opening, cooling water temperature, EHC upstream temperature sensor, SDPF catalyst upstream temperature sensor, SCR catalyst upstream temperature sensor, SCR catalyst downstream temperature sensor, EHC upstream NO x Concentration sensor, NO2 upstream of SCR catalyst x Concentration sensor, NOx downstream of SCR catalyst x The signals from the concentration sensor, urea level sensor, etc. are calculated by the corresponding control function module to complete the coordinated and efficient distribution of the reducing agent of the two-stage injection system, thereby optimizing the passive regeneration performance of PM on the SDPF and improving the overall DeNO of the two-stage SCR system. x The goal of efficiency.

[0078] See also Figure 3, shown in the figure, is a workflow diagram for the aftertreatment heating control strategy. First, the target aftertreatment system's catalytic unit configuration is identified and a corresponding substrate temperature estimation model is established to estimate the substrate temperature of the catalyst units involved in the control strategy. The aftertreatment system's operating status is then assessed to determine whether a temperature increase is required. When the average value of the temperature sensors before and after the DOC falls below the DOC light-off temperature (e.g., 150°C), the aftertreatment system is deemed to require a temperature increase. HC emission mass flow is recorded, and the actual HC accumulation / removal rate on the DOC is calculated in real time using the HC adsorption / desorption rate model. The accumulated HC mass on the DOC is then integrated to determine the cumulative heat release of this HC. The target heating time is then determined using the EHC rated heating power, exhaust mass flow, and DOC substrate temperature. The maximum EHC heat release during this time is then calculated. The total target energy required to raise the temperature to the lower limit of the SCR substrate's efficient temperature window is then calculated based on the current SCR substrate temperature. When the sum of the heat released by HC oxidation and the EHC heat released during the target temperature-raising time is greater than the total target energy, the EHC heating release condition is met. Subsequently, the EHC heating power and fuel post-injection amount are closed-loop controlled with the target temperature rise rate of the SCR carrier as the closed-loop control target. When it is detected that the SCR carrier temperature exceeds the lower limit of the high-efficiency temperature window by more than 20°C, the EHC heating function is stopped, and the cold start heating requirement of the after-treatment system is met.

[0079] See also Figure 1 , which is a flow chart of a method for predicting diesel engine exhaust concentration by grading in a first embodiment of the present invention, the method comprises steps S1 to S12, wherein:

[0080] 1. An EHC heating control method based on HC accumulation effect, characterized in that the method comprises:

[0081] S1: Acquire the working state of the post-processing system to determine whether the post-processing system needs to be heated according to the working state of the post-processing system;

[0082] Specifically, in this step, in order to confirm whether there is a need to increase the temperature, the temperature value of the DOC pre-temperature sensor and the temperature value of the DOC post-temperature sensor are obtained, and the average temperature value is calculated based on the temperature values of the DOC pre-temperature sensor and the temperature values of the DOC post-temperature sensor;

[0083] Determining whether the average temperature value is less than the DOC ignition temperature;

[0084] If the average temperature value is less than the DOC light-off temperature, it is determined that the after-treatment system needs to be heated up. The DOC light-off temperature is generally 150°C.

[0085] S2: If the after-treatment system needs to increase its temperature, the HC emission mass flow rate after the engine is started is integrated to obtain the HC cumulative mass and HC cumulative heat release on the DOC;

[0086] S3: determining whether the sum of the HC cumulative heat release and the EHC heat release during the target warming time is greater than the total target energy;

[0087] It should be noted that the steps for obtaining the total target energy are: using the EHC heating power, exhaust mass flow rate and DOC carrier temperature to determine the target heating time and the EHC heat release within the target heating time; and calculating the total target energy required to heat the SCR carrier to the lower limit of the SCR carrier high-efficiency temperature window based on the current SCR carrier temperature.

[0088] See also Figure 6 First, the SCR carrier temperature estimation model is used to calculate the current SCR carrier temperature using the sensor-measured SCR inlet and outlet exhaust temperatures and exhaust mass flow rate. The current SCR carrier temperature is compared with the lower limit of the SCR carrier's efficient temperature window. The energy input required to raise the carrier temperature is calculated using the carrier's specific heat capacity. The thermal efficiency of heat exchange between the SCR carrier and the exhaust is then calculated based on a thermodynamic process model, resulting in the required energy at the SCR inlet and outlet exhaust. Based on the current SCR inlet exhaust temperature and the required energy, the total target energy required to raise the carrier temperature to the lower limit of the efficient temperature window is calculated. The total target energy required to raise the temperature to the lower limit of the efficient temperature window is calculated using the SCR carrier thermodynamic model. If the sum of the HC oxidation heat release corresponding to the current real-time HC storage level and the EHC heat release during the target warm-up time exceeds the total target energy, EHC heating is triggered.

[0089] The thermal efficiency of the heat exchange between the SCR substrate and the exhaust gas is estimated by a thermodynamic model and corrected in real time by the exhaust gas temperature downstream of the SCR.

[0090] The establishment method and model parameterization method of the SCR carrier thermodynamic model are consistent with the DOC carrier temperature estimation model.

[0091] S4: If the sum of the HC cumulative heat release and the EHC heat release during the target heating time is greater than the total target energy, it is determined that the EHC heating function release condition is met, and the EHC heating power is set.

[0092] See also Figure 4First, the DOC carrier temperature estimation model calculates the DOC carrier temperature under low-temperature conditions using the DOC inlet and outlet exhaust temperatures and exhaust mass flow as inputs. Then, using the EHC rated heating power, DOC carrier temperature, and exhaust mass flow as inputs, the target heating time under the current DOC carrier temperature conditions is obtained by querying the post-processing target heating time calibration map. The actual EHC heating power is calculated based on the current actual battery voltage signal and multiplied by the target heating time to obtain the EHC heating value within the target heating time.

[0093] The DOC carrier temperature estimation model mainly models the following thermodynamic processes: 1) convective heat transfer between the exhaust and the catalyst; 2) heat conduction inside the catalyst; and 3) radiation heat transfer from the catalyst housing to the atmosphere. The details are as follows:

[0094] The convective heat transfer Φ between exhaust gas and catalyst per unit time is calculated according to the following formula P-C :

[0095] Φ P-C =hA H-T (T P -T C )

[0096] Where: h is the heat transfer coefficient of exhaust gas and catalyst convection heat transfer, W / (m 2 K); TP is the exhaust temperature, K; TC is the catalyst temperature, K; A H-T The total surface area of the catalyst that can contact the exhaust gas; ε is used to represent the porosity of the catalyst, Scat is the internal surface area of the catalyst per unit volume of gas that can flow through the catalyst, m 2 / m 3 , then A is calculated according to the following formula H-T :

[0097]

[0098] Among them, r C is the catalyst cross-sectional radius, m; L C is the length of the catalyst, m; is the total volume of the catalyst VC; is the total cross-sectional area of the catalyst; is the area where the exhaust is blocked by the catalyst.

[0099] The heat Φ of the catalyst per unit time through heat conduction is calculated according to the following formula C :

[0100]

[0101] Among them, λ Crepresents the thermal conductivity of the catalyst carrier, X represents the length of the microelement along the heat transfer direction, r c represents the carrier radius, ε represents the porosity, T C Indicates the carrier temperature.

[0102] The radiation heat transfer Φ of the catalyst shell to the atmosphere is calculated according to the following formula C-amb :

[0103]

[0104] Among them, A Rad is the radiation area between the catalyst and the outside world, m 2 ; ε Rad is the radiation blackness; σ SB is the gas radiation constant, W / m 2 K 4 ;T amb is the ambient temperature, K.

[0105] The parameter identification of the DOC carrier temperature estimation model is completed through catalyst sample testing. The identification of thermodynamic parameters is mainly achieved by conducting step temperature rise tests. Standard exhaust gas with temperatures of 200℃, 250℃, 300℃, 350℃, 400℃, 500℃, and 600℃ is introduced in sequence. The exhaust temperature remains unchanged before reaching thermal equilibrium each time. At the same time, the relationship curve of the catalyst carrier temperature at different positions with time, the carrier radiation heat release rate, etc. are recorded; the thermodynamic parameters that need to be confirmed are: the effective flow volume V of the carrier DOC , effective cross-sectional area of the carrier A fr_DOC , convective heat transfer coefficient h DOC , thermal conductivity λ DOC , effective heat exchange area A H-T_DOC , heat radiation area A Rad_DOC , carrier specific heat capacity c p,C(DOC) .

[0106] The target temperature rise time calibration MAP for after-treatment is obtained through electric heating tests of the after-treatment system at different exhaust mass flow rates. The target after-treatment system undergoes several steady-state cold start tests at different speeds and torques on the test bench. By recording the relationship between the respective DOC and SCR carrier temperatures and time, the target temperature rise time corresponding to different DOC carrier temperatures can be obtained.

[0107] It should also be noted that, please refer to Figure 5 The HC emission concentration MAP is obtained by looking up the engine speed, main injection amount, and post-injection amount. In addition, the intake temperature, intake pressure, oil temperature, and cooling water temperature all affect the combustion and power generation processes in the cylinder and need to be corrected respectively. After the HC emission concentration is obtained, the mass flow rate of HC emissions can be calculated in real time in combination with the exhaust mass flow rate.

[0108] Then, through the established HC adsorption rate model, the real-time desorption rate and the maximum adsorption rate are calculated with the exhaust mass flow, the calculated HC real-time storage amount and the DOC carrier temperature as inputs, and the actual HC accumulation / removal rate is calculated with the maximum adsorption rate and the HC emission mass flow. When the HC emission mass flow is greater than or equal to the maximum adsorption rate, the HC accumulation / removal rate on the DOC is equal to the maximum adsorption rate under the current conditions minus the desorption rate under the current conditions; when the HC emission mass flow is less than the maximum adsorption rate, the HC accumulation / removal rate on the DOC is equal to the HC emission mass flow under the current conditions minus the desorption rate under the current conditions. The calculated result of the HC accumulation / removal rate on the DOC will be added to the HC real-time storage amount counter, and the updated HC real-time storage amount will be used as the input of the HC adsorption / desorption rate model in the next calculation. At the same time, the HC real-time storage amount is multiplied by the HC average calorific value to calculate the oxidation heat released by the stored HC. The integration process continues after the start of the cold start driving cycle;

[0109] The HC adsorption and desorption rate model uses DOC carrier temperature, exhaust mass flow, and real-time HC storage as inputs, and calculates the maximum HC adsorption rate and real-time HC desorption rate of the DOC carrier in real time. Establishing the HC adsorption and desorption rate model requires conducting HC storage and clearance tests at different temperatures and exhaust mass flow rates using a DOC catalyst sample on a sample performance test bench to obtain the actual adsorption and desorption rates at different HC storage levels at the target carrier temperature and exhaust mass flow rate. The carrier temperature during the modeling test is measured using a thermocouple on the sample test bench. During actual vehicle application, the DOC carrier temperature is estimated using an established DOC carrier temperature estimation model.

[0110] S5: Recording the SCR substrate temperature and temperature rise rate every first preset time;

[0111] S6: Determine whether the SCR carrier temperature is greater than a first preset temperature threshold, where the first preset temperature threshold is the sum of a high-efficiency temperature window lower limit and a second preset temperature adjustment threshold;

[0112] S7: If the SCR carrier temperature is greater than a first preset temperature threshold, controlling the EHC heating to stop;

[0113] S8: If the SCR carrier temperature is less than or equal to a first preset temperature threshold, determining whether the temperature rise rate is greater than the first preset temperature rise rate threshold;

[0114] S9: If the temperature rise rate is greater than a first preset temperature rise rate threshold, reducing the EHC heating power by a first preset adjustment power threshold, and repeating steps S5 to S6;

[0115] S10: If the temperature rise rate is less than or equal to a first preset temperature rise rate threshold, determining whether the temperature rise rate is greater than a second preset temperature rise rate threshold;

[0116] S11: If the temperature rise rate is greater than the second preset temperature rise rate threshold, increasing the fuel post-injection amount by the first preset fuel post-injection amount threshold, and repeating steps S5 to S6;

[0117] S12: If the temperature rise rate is less than or equal to the second preset temperature rise rate threshold, directly repeat steps S5 to S6 until the SCR carrier temperature is greater than the first preset temperature threshold.

[0118] See also Figure 7 Once the EHC begins heating, closed-loop control of its heating power and post-injection fuel volume is required. The closed-loop control objective is to maintain the target temperature lower limit within the specified time while minimizing the heating rate to near the target temperature rise rate. This prevents the degradation of heating efficiency associated with continuous full-load operation of the EHC and reduces the risk of high-temperature damage from concentrated HC oxidation over a short period of time.

[0119] When the SCR substrate temperature exceeds the lower limit of the high-efficiency temperature window, the catalyst conversion efficiency approaches 100%. At this point, increasing the substrate temperature does not improve the after-treatment system's DeNOx performance, making heating unwise. However, due to temperature lag, if the interval between the lower temperature limit for EHC activation and the upper temperature limit for deactivation is too small, the EHC can frequently cycle on and off, negatively impacting system reliability and service life. Therefore, the present invention selects the lower limit of the high-efficiency temperature window + 20°C as the trigger for EHC deactivation. After the EHC is deactivated, if the engine continues operating at low load, causing the SCR substrate temperature to drop, fuel post-injection is preferred for thermal compensation, as the DOC substrate temperature is significantly above its light-off temperature. Low engine load conditions typically correspond to low NOx emissions. In these conditions, fuel post-injection can mitigate the drop in SCR substrate temperature, effectively converting this NOx using only the higher ammonia storage capacity of the SCR catalyst.

[0120] Closed-loop control is based on the control equations for the aftertreatment system's thermal management process. These equations are based on the following assumptions: 1) HC oxidation occurs entirely within the DOC carrier space; 2) thermal radiation losses from the DOC carrier during this phase are ignored; 3) the internal heat transfer rate within the DOC carrier is assumed to be extremely fast, resulting in a uniform carrier temperature distribution; and 4) changes in gas pressure and flow rate before and after passing through the DOC are ignored. In this case, the following two energy conservation relationships hold:

[0121] ① HC oxidation heat + EHC heat + DOC inlet exhaust heat = DOC outlet exhaust heat + DOC carrier absorbed heat;

[0122] ②The heat of exhaust gas at the SCR inlet = the heat of exhaust gas at the SCR outlet + the heat absorbed by the SCR carrier;

[0123] The HC oxidation heat release per unit time can be calculated by a chemical reaction kinetic model of the HC oxidation reaction (the model inputs are: real-time HC storage amount, fuel post-injection amount, DOC carrier temperature, O2 concentration, exhaust mass flow rate, and the model output is the HC oxidation reaction rate); the EHC heat release per unit time can be obtained from the real-time heating power of the EHC; the heat possessed by the exhaust gas at the DOC inlet can be calculated by the DOC inlet temperature sensor signal and the exhaust mass flow signal; the heat possessed by the exhaust gas at the DOC outlet can be calculated by the DOC outlet temperature sensor signal and the exhaust mass flow signal; thereby, the energy absorbed by the DOC carrier can be calculated and the temperature rise rate of the DOC can be calculated based on the specific heat capacity of the DOC carrier; if the calculated DOC temperature rise rate exceeds the upper limit of the thermal protection temperature rise rate, the EHC heating is stopped

[0124] The heat content of the exhaust gas at the SCR inlet can be calculated by the SCR inlet temperature sensor signal and the exhaust mass flow signal; the heat content of the exhaust gas at the SCR outlet can be calculated by the SCR outlet temperature sensor signal and the exhaust mass flow signal; thereby, the energy absorbed by the SCR carrier can be calculated and the temperature rise rate of the SCR can be calculated based on the specific heat capacity of the SCR carrier; after the EHC operates at rated power for 5 seconds, if the real-time temperature rise rate of the SCR is lower than the target temperature rise rate (the present invention selects 80%), the temperature raising capacity of the after-treatment system is further enhanced by increasing the fuel post-injection (but the total fuel post-injection amount must not exceed the calibrated limit, such as 5 mg / stk); if the real-time temperature rise rate of the SCR is higher than the target temperature rise rate by a certain degree (the present invention selects 150%), the EHC heating power is reduced to avoid wasting heating energy while also reducing the risk of thermal stress.

[0125] The target temperature rise rate is obtained by conducting temperature rise tests under different carrier temperatures and exhaust mass flow rates, and is obtained by looking up the target temperature rise time and the current temperature difference in the control model. The smaller the temperature difference, the lower the target temperature rise rate.

[0126] In summary, the EHC heating control method based on the HC accumulation effect proposed in this embodiment can enhance the thermal management control system's ability to raise the temperature of the aftertreatment system by promoting the concentrated oxidation of HC stored on the carrier before the DOC reaches the light-off temperature, thereby releasing a large amount of heat. This helps achieve rapid aftertreatment system heating. This heating control strategy accelerates the time it takes for the SCR system to reach the injection start temperature, effectively controlling NOx and HC emissions during cold start, while significantly improving the system's chemical and electrical energy utilization, thereby enhancing the vehicle's overall fuel economy.

[0127] See also Figure 8 , which is a schematic structural diagram of an EHC heating control system based on HC accumulation effect in a second embodiment of the present invention, the system includes:

[0128] The temperature increase demand monitoring module 10 is used to obtain the working status of the post-processing system to determine whether the post-processing system needs to increase its temperature according to the working status of the post-processing system;

[0129] Furthermore, the temperature increase demand monitoring module 10 further includes:

[0130] an average temperature value calculation unit, configured to obtain a temperature value of a DOC pre-temperature sensor and a temperature value of a DOC post-temperature sensor, and calculate an average temperature value based on the temperature values of the DOC pre-temperature sensor and the DOC post-temperature sensor;

[0131] an average temperature value monitoring unit, for determining whether the average temperature value is less than the DOC ignition temperature;

[0132] If the average temperature value is less than the DOC light-off temperature, it is determined that there is a need to increase the temperature of the after-treatment system.

[0133] an integral calculation module, configured to perform an integral calculation on the HC emission mass flow rate after the engine is started if there is a need to increase the temperature of the after-treatment system, to obtain the HC cumulative mass and HC cumulative heat release on the DOC;

[0134] a total target energy monitoring module 20 for determining whether the sum of the HC cumulative heat release and the EHC heat release during the target warming time is greater than the total target energy;

[0135] Furthermore, the total target energy monitoring module 20 further includes:

[0136] An EHC heat release acquisition unit is configured to determine a target heating time and the EHC heat release within the target heating time using the EHC heating power, the exhaust mass flow rate, and the DOC carrier temperature;

[0137] Furthermore, the EHC heat release acquisition unit further includes:

[0138] The first DOC carrier temperature calculation subunit is used for the DOC carrier temperature estimation model to calculate the DOC carrier temperature under low temperature conditions using the DOC inlet exhaust temperature, the DOC outlet exhaust temperature and the exhaust mass flow rate as inputs;

[0139] The target heating time acquisition subunit is used for the DOC carrier temperature estimation model. It takes the EHC rated heating power, DOC carrier temperature and exhaust mass flow as inputs, and obtains the target heating time under the current DOC carrier temperature conditions by checking the post-processing target heating time calibration MAP;

[0140] The EHC heat release calculation subunit is used to calculate the actual heating power of the EHC based on the current actual battery voltage signal, and then multiply the actual heating power of the EHC by the target heating time to obtain the EHC heat release within the target heating time.

[0141] The total target energy calculation unit is used to calculate the total target energy required to raise the temperature to the lower limit of the SCR carrier high-efficiency temperature window according to the current SCR carrier temperature.

[0142] Furthermore, the total target energy calculation unit further includes:

[0143] The second carrier temperature calculation subunit is used to calculate the current SCR carrier temperature using the SCR inlet exhaust temperature, SCR outlet exhaust temperature and exhaust mass flow rate measured by the sensor, using the established SCR carrier temperature estimation model, comparing the current SCR carrier temperature with the lower limit of the SCR carrier high-efficiency temperature window, and calculating the energy input required to raise the carrier temperature based on the carrier specific heat capacity;

[0144] The total target energy acquisition subunit is used to calculate the thermal efficiency of the heat exchange between the SCR carrier and the exhaust gas based on the thermodynamic process model, obtain the energy required for the exhaust gas at the SCR inlet and the energy required for the exhaust gas at the SCR outlet, and calculate the total target energy required to increase the temperature to the lower limit of the carrier's high-efficiency temperature window based on the current SCR inlet exhaust temperature and the energy required for the exhaust gas at the SCR inlet.

[0145] a heating power setting module 30 for determining that an EHC heating function release condition is satisfied if the sum of the HC cumulative heat release and the EHC heat release during the target heating time is greater than the total target energy, and setting the EHC heating power;

[0146] A real-time recording module 40 is configured to record the SCR substrate temperature and temperature rise rate at first preset intervals;

[0147] An SCR carrier temperature monitoring module 50 is configured to determine whether the SCR carrier temperature is greater than a first preset temperature threshold, where the first preset temperature threshold is the sum of a high-efficiency temperature window lower limit and a second preset temperature adjustment threshold;

[0148] An EHC heating stop execution module 60 is configured to control EHC heating to stop if the SCR carrier temperature is greater than a first preset temperature threshold;

[0149] a first temperature rise rate monitoring module 70 for determining whether the temperature rise rate is greater than a first preset temperature rise rate threshold if the SCR carrier temperature is less than or equal to a first preset temperature threshold;

[0150] a heating power regulating module 80 for reducing the EHC heating power by the first preset regulating power threshold if the temperature rise rate is greater than a first preset temperature rise rate threshold, and repeatedly recording the SCR substrate temperature and the temperature rise rate;

[0151] a second temperature rise rate monitoring module 90 for determining whether the temperature rise rate is greater than a second preset temperature rise rate threshold if the temperature rise rate is less than or equal to the first preset temperature rise rate threshold;

[0152] If the temperature rise rate is less than or equal to a second preset temperature rise rate threshold, repeatedly recording the SCR carrier temperature and the temperature rise rate until the SCR carrier temperature is greater than a first preset temperature threshold;

[0153] The fuel post-injection amount adjustment module 100 is configured to increase the fuel post-injection amount by a first preset fuel post-injection amount threshold if the temperature rise rate is greater than a second preset temperature rise rate threshold, and repeatedly record the SCR substrate temperature and the temperature rise rate.

[0154] Furthermore, in some optional embodiments of the present invention, the system further includes:

[0155] The convection heat transfer calculation module is used to calculate the convection heat transfer Φ between the exhaust and the catalyst per unit time according to the following formula P-C :

[0156] Φ P-C =hA H-T (T P -T C )

[0157] Where: h is the heat transfer coefficient of exhaust gas and catalyst convection heat transfer, W / (m 2 K); TP is the exhaust temperature, K; TC is the catalyst temperature, K; A H-T The total surface area of the catalyst that can contact the exhaust gas; ε is used to represent the porosity of the catalyst, Scat is the internal surface area of the catalyst per unit volume of gas that can flow through the catalyst, m2 / m 3 , then A is calculated according to the following formula H-T :

[0158]

[0159] Among them, r C is the catalyst cross-sectional radius, m; L C is the length of the catalyst, m; is the total volume of the catalyst VC; is the total cross-sectional area of the catalyst; is the area where the exhaust is blocked by the catalyst.

[0160] The heat conduction heat calculation module is used to calculate the heat Φ of the catalyst through heat conduction per unit time according to the following formula C :

[0161]

[0162] Among them, λ C represents the thermal conductivity of the catalyst carrier, X represents the length of the microelement along the heat transfer direction, r c represents the carrier radius, ε represents the porosity, T C Indicates the carrier temperature.

[0163] The radiation heat transfer calculation module is used to calculate the radiation heat transfer Φ of the catalyst shell to the atmosphere according to the following formula C-amb :

[0164]

[0165] Among them, A Rad is the radiation area between the catalyst and the outside world, m 2 ; ε Rad is the radiation blackness; σ SB is the gas radiation constant, W / m 2 K 4 ;T amb is the ambient temperature, K.

[0166] Throughout this specification, reference to terms such as "one embodiment," "some embodiments," "examples," "specific examples," or "some examples" means that a specific feature, structure, material, or characteristic described in conjunction with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0167] The above-described embodiments merely illustrate several implementations of the present invention, and while their descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims.

Claims

1. An EHC heating control method based on HC accumulation effect, characterized in that: The method comprises: S1: Acquire the working state of the post-processing system to determine whether the post-processing system needs to be heated according to the working state of the post-processing system; S2: If the after-treatment system needs to increase its temperature, the HC emission mass flow rate after the engine is started is integrated to obtain the HC cumulative mass and HC cumulative heat release on the DOC; S3: determining whether the sum of the HC cumulative heat release and the EHC heat release during the target warming time is greater than the total target energy; S4: If the sum of the HC cumulative heat release and the EHC heat release during the target heating time is greater than the total target energy, it is determined that the EHC heating function release condition is met, and the EHC heating power is set. S5: Recording the SCR substrate temperature and temperature rise rate every first preset time; S6: Determine whether the SCR carrier temperature is greater than a first preset temperature threshold, where the first preset temperature threshold is the sum of a high-efficiency temperature window lower limit and a second preset temperature adjustment threshold; S7: If the SCR carrier temperature is greater than a first preset temperature threshold, controlling the EHC heating to stop; S8: If the SCR carrier temperature is less than or equal to a first preset temperature threshold, determining whether the temperature rise rate is greater than the first preset temperature rise rate threshold; S9: If the temperature rise rate is greater than a first preset temperature rise rate threshold, reducing the EHC heating power by a first preset adjustment power threshold, and repeating steps S5 to S6; S10: If the temperature rise rate is less than or equal to a first preset temperature rise rate threshold, determining whether the temperature rise rate is greater than a second preset temperature rise rate threshold; S11: If the temperature rise rate is greater than the second preset temperature rise rate threshold, increasing the fuel post-injection amount by the first preset fuel post-injection amount threshold, and repeating steps S5 to S6; S12: If the temperature rise rate is less than or equal to the second preset temperature rise rate threshold, directly repeat steps S5 to S6 until the SCR carrier temperature is greater than the first preset temperature threshold.

2. The EHC heating control method based on HC accumulation effect according to claim 1, characterized in that: The step of obtaining the working status of the post-processing system and determining whether the post-processing system needs to be heated according to the working status of the post-processing system includes: Acquire a temperature value of a DOC front temperature sensor and a DOC rear temperature sensor, and calculate an average temperature value based on the temperature value of the DOC front temperature sensor and the temperature value of the DOC rear temperature sensor; Determining whether the average temperature value is less than the DOC ignition temperature; If the average temperature value is less than the DOC light-off temperature, it is determined that there is a need to increase the temperature of the after-treatment system.

3. The EHC heating control method based on HC accumulation effect according to claim 1, characterized in that: The step of determining whether the sum of the HC cumulative heat release and the EHC heat release during the target warming time is greater than the total target energy includes: Determining a target heating time and an amount of heat released by the EHC during the target heating time using the EHC heating power, the exhaust mass flow rate, and the DOC carrier temperature; The total target energy required to raise the temperature of the SCR substrate to the lower limit of the SCR substrate high-efficiency temperature window is calculated based on the current SCR substrate temperature.

4. The EHC heating control method based on HC accumulation effect according to claim 3, characterized in that: The step of determining the target heating time and the amount of heat released by the EHC during the target heating time by using the EHC heating power, the exhaust mass flow rate, and the DOC carrier temperature includes: The DOC carrier temperature estimation model takes the DOC inlet exhaust temperature, DOC outlet exhaust temperature and exhaust mass flow rate as inputs to calculate the DOC carrier temperature under low temperature conditions; The DOC carrier temperature estimation model takes the EHC rated heating power, DOC carrier temperature and exhaust mass flow as inputs, and obtains the target heating time under the current DOC carrier temperature conditions by checking the post-processing target heating time calibration MAP; After calculating the actual heating power of the EHC based on the current actual battery voltage signal, the actual heating power of the EHC is multiplied by the target heating time to obtain the amount of heat released by the EHC within the target heating time.

5. The EHC heating control method based on HC accumulation effect according to claim 3, characterized in that: The step of calculating the total target energy required to raise the temperature to the lower limit of the SCR carrier high-efficiency temperature window according to the current SCR carrier temperature includes: The SCR inlet exhaust temperature, SCR outlet exhaust temperature, and exhaust mass flow rate measured by the sensor are used as inputs. The current SCR carrier temperature is calculated using the established SCR carrier temperature estimation model. The current SCR carrier temperature is compared with the lower limit of the SCR carrier high-efficiency temperature window, and the energy input required to raise the carrier temperature is calculated based on the carrier specific heat capacity. The thermal efficiency of the heat exchange between the SCR carrier and the exhaust gas is calculated based on the thermodynamic process model to obtain the energy required for the exhaust gas at the SCR inlet and the energy required for the exhaust gas at the SCR outlet. The total target energy required to increase the temperature to the lower limit of the carrier's high-efficiency temperature window is calculated based on the current SCR inlet exhaust temperature and the energy required for the exhaust gas at the SCR inlet.

6. The EHC heating control method based on HC accumulation effect according to claim 1, characterized in that: If the after-treatment system needs to increase its temperature, the step of integrating the HC emission mass flow rate after the engine is started to obtain the HC cumulative mass and HC cumulative heat release on the DOC also includes: The real-time desorption rate and maximum adsorption rate are calculated using the exhaust mass flow rate, the calculated real-time HC storage amount, and the DOC carrier temperature as inputs, and the actual HC accumulation / removal rate is calculated using the maximum adsorption rate and the HC emission mass flow rate. When the HC emission mass flow rate is less than the maximum adsorption rate, the HC accumulation / removal rate on the DOC is equal to the HC emission mass flow rate under the current conditions minus the desorption rate under the current conditions.

7. The EHC heating control method based on HC accumulation effect according to claim 4, characterized in that: The DOC carrier temperature estimation model includes modeling of three thermodynamic processes, including convection heat transfer between exhaust and catalyst, heat conduction inside the catalyst, and radiation heat transfer from the catalyst housing to the atmosphere, wherein: The convective heat transfer between exhaust gas and catalyst per unit time is calculated according to the following formula : Where: h is the heat transfer coefficient of exhaust gas and catalyst convection heat transfer, W / (m 2 •K); is the exhaust temperature, K; is the catalyst temperature, K; A H-T The total surface area of the catalyst that can come into contact with the exhaust gas; represents the porosity of the catalyst, S cat Indicates the internal surface area of the catalyst per unit volume of gas that can flow through the catalyst, m 2 / m 3 , then A is calculated according to the following formula H-T : in, is the catalyst cross-sectional radius, m; L C is the length of the catalyst, m; is the total volume of the catalyst VC; is the total cross-sectional area of the catalyst; is the area where the exhaust is blocked by the catalyst.

8. The EHC heating control method based on HC accumulation effect according to claim 7, characterized in that: The heat generated by heat conduction of the catalyst per unit time can be calculated according to the following formula : in, represents the thermal conductivity of the catalyst carrier, X represents the length of the microelement along the heat transfer direction, r c represents the catalyst cross-sectional radius, represents the porosity of the catalyst, Indicates the carrier temperature.

9. The EHC heating control method based on HC accumulation effect according to claim 7, characterized in that: The radiation heat transfer from the catalyst shell to the atmosphere is calculated according to the following formula: : in, is the radiation area between the catalyst and the outside world, m 2 ; is the radiation blackness; is the gas radiation constant, W / m 2 K 4 ;T amb is the ambient temperature, K.

10. An EHC heating control system based on HC accumulation effect, characterized in that: The system comprises: A temperature increase demand monitoring module is used to obtain the working status of the post-processing system to determine whether the post-processing system needs to increase its temperature according to the working status of the post-processing system; an integral calculation module, configured to perform an integral calculation on the HC emission mass flow rate after the engine is started if there is a need to increase the temperature of the after-treatment system, to obtain the HC cumulative mass and HC cumulative heat release on the DOC; a total target energy monitoring module, configured to determine whether the sum of the accumulated heat release of the HC and the heat release of the EHC during the target warming time is greater than the total target energy; a heating power setting module, configured to determine that an EHC heating function release condition is satisfied if the sum of the HC cumulative heat release and the EHC heat release within the target heating time is greater than the total target energy, and to set the EHC heating power; A real-time recording module, configured to record the SCR substrate temperature and temperature rise rate at first preset time intervals; An SCR carrier temperature monitoring module is configured to determine whether the SCR carrier temperature is greater than a first preset temperature threshold, where the first preset temperature threshold is the sum of a high-efficiency temperature window lower limit and a second preset temperature adjustment threshold; an EHC heating stop execution module, configured to control EHC heating to stop if the SCR carrier temperature is greater than a first preset temperature threshold; a first temperature rise rate monitoring module, configured to determine whether the temperature rise rate is greater than a first preset temperature rise rate threshold if the SCR carrier temperature is less than or equal to a first preset temperature threshold; a heating power regulating module, configured to reduce the EHC heating power by the first preset regulating power threshold if the temperature rise rate is greater than a first preset temperature rise rate threshold, and repeatedly record the SCR substrate temperature and the temperature rise rate; a second temperature rise rate monitoring module, configured to determine whether the temperature rise rate is greater than a second preset temperature rise rate threshold if the temperature rise rate is less than or equal to the first preset temperature rise rate threshold; If the temperature rise rate is less than or equal to a second preset temperature rise rate threshold, repeatedly recording the SCR carrier temperature and the temperature rise rate until the SCR carrier temperature is greater than a first preset temperature threshold; The fuel post-injection amount adjustment module is configured to increase the fuel post-injection amount by the first preset fuel post-injection amount threshold if the temperature rise rate is greater than the second preset temperature rise rate threshold, and repeatedly record the SCR substrate temperature and the temperature rise rate.

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