Engine operating point selection and adjustment method considering LNT and fuel injection advance angle

Abstract

The application relates to an engine working point selection and adjustment method considering LNT and fuel injection advance angle, which calculates the oxidation speed of each candidate working point of the engine under a corresponding working condition point, the discharge of NO2, the PM carbon load in a CDPF, the temperature of the CDPF, the flow of NO2 in the LNT, the reduction speed of current NO2, the PM carbon load in the LNT, the temperature of the LNT, the average system effective fuel consumption rate under the fuel injection advance angle, selects the candidate working point with the minimum average system effective fuel consumption rate as the optimal working point of the engine under the current CDPF regeneration timing and LNT and fuel injection advance angle control, and applies the optimal working point. Compared with the prior art, the application considers the fuel consumption increase caused by the delay of the fuel injection advance angle and the speed of generating reducing gas, that is, the NOx reduction efficiency in the LNT, and can improve the comprehensive efficiency of a diesel hybrid system.

Description

Technical Field

[0001] This invention relates to the field of hybrid vehicle technology, and in particular to a method for selecting and adjusting the engine operating point that takes into account both LNT (Low-Temperature) and injection advance angle. Background Technology

[0002] Diesel engine emissions are strictly regulated by national emission regulations, and these regulations are becoming increasingly stringent as the country places greater emphasis on environmental protection. Diesel engine emissions include CO, NOx, HC, and PM. Because diesel engines use a relatively high average air-fuel ratio, CO and HC emissions are not a major concern, while PM and NOx emissions are significantly more problematic. PM primarily originates from the high-temperature, oxygen-deficient region of combustion, while NOx, conversely, originates from the high-temperature, oxygen-rich region. Therefore, the more NOx generated, the less PM is generated, and vice versa. With increasingly stringent emission regulations, simply optimizing the engine's mechanical structure and software control is no longer sufficient to meet current emission requirements; after-treatment devices are necessary to treat NOx and PM.

[0003] There are two methods for treating NOx: Light-Nitrogen (LNT) adsorption catalytic reduction (LNT) and Selective Catalytic Reduction (SCR). Compared to SCR, LNT has a more compact structure, lower manufacturing cost, and can directly use fuel as a reducing agent, eliminating the need for a dedicated onboard container and supply infrastructure for the reducing agent. This makes it particularly suitable for diesel vehicles with displacements smaller than 2.0-2.5L, which are often space-constrained and require compact design. Therefore, passenger cars typically choose LNT, while commercial vehicles more often opt for SCR. When a diesel engine operates with a lean air-fuel mixture, NOx is adsorbed onto the alkaline metal of the LNT. Once the LNT reaches saturation, it can no longer adsorb NOx, requiring the formation of a rich mixture in the exhaust gas to directly reduce the NOx. This process also generates large amounts of HC, CO, and CO2 around the adsorption catalyst, causing CO2 to displace the NO2 from the alkaline metal. This rich mixture continues until all the NO2 has been replaced by CO2. Under catalysis, the NO and NO2 released by the catalyst react with CO, HC and H2 to produce harmless CO2, N2 and H2O.

[0004] In the LNT regeneration process, the required rich mixture can be achieved by reducing the efficiency of the diesel engine, for example, by retarding the diesel engine's injection advance angle, adding a secondary injection after the main fuel injection, or injecting fuel into the exhaust pipe. The first two methods, in particular, can be implemented with existing hardware and have the lowest hardware requirements. Adding a secondary injection after the main fuel injection increases the exhaust temperature after combustion, increases PM oxidation, and reduces PM emissions; however, it has little impact on the maximum in-cylinder pressure during combustion, therefore, its impact on NOx emissions is also relatively small. In contrast, changing the injection advance angle affects fuel consumption, NOx emissions, and PM emissions.

[0005] Traditional diesel engines using nitrogen oxide adsorption catalytic reduction (LNT) technology require periodic LNT regeneration, typically performed when the LNT is saturated. Furthermore, for traditional automobiles, the engine's operating point (engine torque and speed) is determined by driving conditions and cannot be adjusted.

[0006] Compared to traditional diesel vehicles, diesel hybrid vehicles can flexibly adjust the engine's operating point. Because diesel engines have a wider high-efficiency range, they can maintain fuel economy while simultaneously optimizing the engine's operating point and injection advance angle to better control the additional fuel consumption caused by LNT regeneration. Summary of the Invention

[0007] The purpose of this invention is to overcome the shortcomings of the existing technology and provide an engine operating point selection and adjustment method that takes into account both LNT and injection advance angle. It considers the system efficiency of the entire hybrid system under LNT regeneration conditions, takes NOx emissions and PM emissions into account as equivalent fuel consumption, and optimizes the fuel increment under LNT regeneration conditions.

[0008] The objective of this invention can be achieved through the following technical solutions:

[0009] The first objective of this invention is to provide a method for selecting an engine operating point that takes into account both the LNT (Lane Tolerant Nucleus) and the injection advance angle. Hybrid electric vehicles operate under multiple different conditions, each with different candidate engine operating points. For a given operating point of the hybrid electric vehicle, the following parameters are obtained: current PM oxidation rate, NO2 emission, PM carbon load in the CDPF (Concentrated Dioxide Powder), CDPF temperature, NO2 flow rate in the LNT, current NO2 reduction rate, PM carbon load in the LNT, LNT temperature, and fuel consumption increment due to delayed injection advance angle. These parameters are then used to calculate the fuel consumption increment for that operating point. The average system effective fuel consumption rate at each candidate engine operating point is determined based on the current PM oxidation rate, NO2 displacement, PM carbon load in CDPF, CDPF temperature, NO2 flow rate in LNT, current NO2 reduction rate, PM carbon load in LNT, LNT temperature, and injection advance angle. The candidate operating point with the lowest average system effective fuel consumption rate is selected as the optimal engine operating point, taking into account both CDPF regeneration timing and LNT and injection advance angle control. The formula for calculating the average system effective fuel consumption rate be″′ is as follows:

[0010]

[0011] Where be″′ represents the system's effective fuel consumption rate considering PM oxidation rate, NO2 emission, PM carbon load in CDPF, CDPF temperature, NO2 flow rate in LNT, current NO2 reduction rate, PM carbon load in LNT, LNT temperature, and the system's effective fuel consumption rate after considering the fuel consumption increase caused by retarding the injection advance angle, Q′. fuel P' represents the fuel consumption rate at the candidate operating point under the following conditions: PM oxidation rate, NO2 emission, PM carbon load in CDPF, CDPF temperature, NO2 flow rate in LNT, current NO2 reduction rate, PM carbon load in LNT, LNT temperature, and injection advance angle. P' represents the effective output power of the engine system at the candidate operating point considering energy conversion losses, active regeneration of CDPF and LNT, and exhaust aftertreatment.

[0012] The formula for P′ is as follows:

[0013] When the charging and discharging power of the power battery is equal to that of charging, the formula for P′ is:

[0014] P′ B =P A +P Chg

[0015] Among them, P A This indicates the effective output power of the power battery when its charging and discharging power is 0kW.

[0016] When the charging and discharging power of the power battery is equal to the discharge power, the formula for P′ is:

[0017] P′ C =P A -P Dchg

[0018] Among them, Q′ fuel The formula is as follows:

[0019] Q′ fuel =Q fuel +ΔQ″ fuel

[0020] Among them, Q fuel This represents the overall fuel consumption rate of the engine at a candidate operating point, expressed in g / h, ΔQ″. fuel The fuel consumption rate increased by CDPF or LNT active regeneration and delayed injection advance angle, expressed in g / h.

[0021] Furthermore, ΔQ″ fuel The formula is as follows:

[0022] ΔQ″ fuel =ΔQ fuel +ΔQ′ fuel

[0023] Where, ΔQ fuel The fuel consumption rate of increased fuel consumption due to active regeneration of CDPF or LNT, expressed in g / h; ΔQ′ fuel The fuel consumption rate increased by delaying the injection advance angle, expressed in g / h.

[0024] Furthermore, ΔQ″ fuel The specific formula is as follows:

[0025]

[0026] The reduction of PM, NO2, and NO each requires a certain amount of fuel consumption, with ratios c, respectively. PM and The original NO2 mass flow rate and NO mass flow rate of the engine, Q PM η represents the original PM mass flow rate of the engine; η represents the efficiency of the actual strategy at the candidate operating point.

[0027] Furthermore, k1 characterizes the oxidation rate of PM and is related to NO2 emissions, PM carbon loading in CDPF, and CDPF temperature, as shown below:

[0028]

[0029] Furthermore, k2 characterizes the NO2 reduction rate and is related to the NO2 flow rate in the LNT, the current NO2 reduction rate, the PM carbon loading in the LNT, and the LNT temperature, as shown below:

[0030]

[0031] Furthermore, the engine operating point selection method that takes into account both LNT and injection advance angle includes the following steps:

[0032] S1: Determine the target output torque of the transmission at the operating point;

[0033] S2: Adjust the carbon loading of CDPF to the current carbon loading of CDPF;

[0034] S3: Adjust the torque of the engine and the torque of the motor so that the torque distribution of the engine and the motor meets the target output torque of the transmission at the operating point, obtain multiple candidate operating points of the engine, and combine different candidate operating points.

[0035] S4: Obtain the current PM oxidation rate after DOC, NO2 displacement, PM carbon load in CDPF, CDPF temperature, NO2 flow rate in LNT, current NO2 reduction rate, PM carbon load in LNT, and LNT temperature. Calculate the average system effective fuel consumption rate for each combination, obtain the optimal combination with the minimum average system effective fuel consumption rate, and use the candidate operating point of the optimal combination as the current engine optimal operating point that takes into account both CDPF and LNT.

[0036] The second objective of this invention is to provide a method for adjusting the engine operating point that takes into account both LNT and injection advance angle, including an operating condition table establishment stage and an operating condition table application stage.

[0037] The process for creating the operating condition table is as follows:

[0038] Multiple operating points during the operation of the hybrid vehicle are determined, and the optimal engine operating point for each operating point is obtained under different considerations of CDPF, LNT and injection advance angle, and written into the operating point table. The optimal engine operating point is obtained based on the engine operating point selection method that considers LNT and injection advance angle as described above.

[0039] Furthermore, the work condition table creation phase includes the following steps:

[0040] T1: Determine the carbon load of CDPF, nitrogen displacement of LNT, and injection advance angle; determine the vehicle speed and transmission output torque at a certain operating point.

[0041] T2: Adjust the engine torque and the motor torque, calculate the engine's optimal operating point under the current CDPF carbon load, LNT nitrogen displacement and injection advance angle, and write it into the operating condition table.

[0042] T3: Keep the vehicle speed constant, change the target output torque of the transmission to obtain a new operating point, repeat steps T2-T3 until the optimal engine operating point under the current CDPF carbon load, LNT nitrogen displacement and injection advance angle is obtained at all operating points at the vehicle speed, and write it into the operating point table.

[0043] T4: Change the vehicle speed to obtain a new operating point. Repeat steps T2-T4 until the optimal engine operating point is obtained for all operating points under the current CDPF carbon load, LNT nitrogen displacement and injection advance angle. Write the operating point table.

[0044] T5: Adjust CDPF carbon load and LNT nitrogen displacement, determine the vehicle speed and transmission output torque at a certain operating point, repeat steps T2-T5 until the optimal engine operating point is obtained for all operating points under different CDPF carbon load, LNT nitrogen displacement and injection advance angle, and write it into the operating condition table.

[0045] Furthermore, the application stage of the condition gauge is as follows:

[0046] The system acquires the current PM oxidation rate, NO2 emission, PM carbon load in CDPF, CDPF temperature, NO2 flow rate in LNT, current NO2 reduction rate, PM carbon load in LNT, LNT temperature, and injection advance angle. It then determines the current CDPF carbon load and LNT nitrogen emission. Based on the operating condition table, current vehicle speed, current transmission target output torque, and the current CDPF carbon load, LNT nitrogen emission, and injection advance angle, it obtains and applies the engine's optimal operating point.

[0047] Furthermore, the specific application phase of the operating condition table is as follows:

[0048] Write the operating condition table into the controller of the hybrid vehicle;

[0049] The system obtains the SOC of the power battery, the current vehicle speed, and the current target output torque of the transmission for the hybrid electric vehicle. It determines the current carbon load of the CDPF based on the cumulative reduction of carbon load and the cumulative fuel consumption, determines the current nitrogen emission of the LNT based on the cumulative reduction of NOx mass and the cumulative fuel consumption, and determines the increase in fuel consumption caused by delaying the injection advance angle.

[0050] If the SOC value of the power battery is within the preset threshold range, find the operating point in the operating condition table that is closest to the current vehicle speed and the current transmission target output torque, find the engine's optimal operating point under the current CDPF carbon load, LNT nitrogen displacement and injection advance angle, and apply it.

[0051] If the SOC value of the power battery is not within the preset threshold range, find the operating point in the operating condition table that is closest to the current vehicle speed and the current transmission target output torque. Using the engine's optimal operating point at the current CDPF carbon load, LNT nitrogen displacement and injection advance angle as the benchmark, increase or decrease the effective engine power used to charge the power battery by proportionally using the difference between the power battery SOC and the threshold range, and obtain the engine's optimal operating point and apply it.

[0052] Compared with the prior art, the present invention has the following beneficial effects:

[0053] 1) The engine operating point selection and adjustment method of the present invention, which takes into account both LNT and injection advance angle, designs an evaluation index for the operating point of diesel hybrid vehicle engine, considers the system efficiency of the entire hybrid system under LNT regeneration condition, and takes NOx emissions and PM emissions into account as equivalent fuel consumption to optimize the fuel increment under LNT regeneration condition.

[0054] 2) The engine operating point selection and adjustment method of the present invention, which takes into account both LNT and injection advance angle, is based on active regeneration of LNT by delaying the fuel injection angle. The present invention considers the increase in fuel consumption caused by delaying the injection advance angle and the rate of generating reducing gas, that is, it considers the NOx reduction efficiency in LNT. Through the optimization index of the present invention, the selection of LNT regeneration timing, the selection of the engine basic operating point (speed and torque) under LNT regeneration conditions, and the fuel injection advance angle based on the operating point can be systematically optimized, thereby improving the overall efficiency of the diesel hybrid system. Attached Figure Description

[0055] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0056] Figure 1 This is a schematic diagram of the candidate operating points of the engine in the embodiment.

[0057] Figure 2 This is a schematic diagram illustrating the effect of the injection ignition angle on a commercial vehicle diesel engine at 1300 rpm, 50% load, and without EGR, as shown in the example.

[0058] Figure 3 The curves showing the relationship between the injection advance angle and the cylinder pressure and heat release during combustion are shown in the example. Detailed Implementation

[0059] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0060] The method embodiments of the present invention will now be described in detail.

[0061] Example 1

[0062] This embodiment provides a method for selecting the engine operating point that takes into account both LNT (Light Noise Regeneration) and injection advance angle. The hybrid vehicle operates under multiple different operating conditions, each with different candidate engine operating points. For a given operating condition, the following parameters are obtained: current PM oxidation rate, NO2 displacement, PM carbon load in CDPF (Concentrated Dioxide Powder), CDPF temperature, NO2 flow rate in LNT, current NO2 reduction rate, PM carbon load in LNT, LNT temperature, and fuel consumption increment due to delayed injection advance angle. The average system effective fuel consumption rate is then calculated for each candidate engine operating point under these parameters. The candidate operating point with the lowest average system effective fuel consumption rate is selected as the optimal engine operating point, taking into account both CDPF regeneration timing and LNT and injection advance angle control. The formula for calculating the average system effective fuel consumption rate be″′ is as follows:

[0063]

[0064] Where be″′ represents the system's effective fuel consumption rate considering PM oxidation rate, NO2 emission, PM carbon load in CDPF, CDPF temperature, NO2 flow rate in LNT, current NO2 reduction rate, PM carbon load in LNT, LNT temperature, and the system's effective fuel consumption rate after considering the fuel consumption increase caused by retarding the injection advance angle, Q′. fuelP' represents the fuel consumption rate at the candidate operating point under the following conditions: PM oxidation rate, NO2 emission, PM carbon load in CDPF, CDPF temperature, NO2 flow rate in LNT, current NO2 reduction rate, PM carbon load in LNT, LNT temperature, and injection advance angle. P' represents the effective output power of the engine system at the candidate operating point considering energy conversion losses, active regeneration of CDPF and LNT, and exhaust aftertreatment.

[0065] The formula for P′ is as follows:

[0066] When the charging and discharging power of the power battery is equal to that of charging, the formula for P′ is:

[0067] P′ B =P A +P Chg

[0068] Among them, P A This indicates the effective output power of the power battery when its charging and discharging power is 0kW.

[0069] When the charging and discharging power of the power battery is equal to the discharge power, the formula for P′ is:

[0070] P′ C =P A -P Dchg

[0071] Among them, Q′ fuel The formula is as follows:

[0072] Q′ fuel =Q fuel +ΔQ″ fuel

[0073] Among them, Q fuel This represents the overall fuel consumption rate of the engine at a candidate operating point, expressed in g / h, ΔQ″. fuel The fuel consumption rate increased by CDPF or LNT active regeneration and delayed injection advance angle, expressed in g / h.

[0074] ΔQ″ fuel The formula is as follows:

[0075] ΔQ″ fuel =ΔQ fuel +ΔQ′ fuel

[0076] Where, ΔQ fuel The fuel consumption rate of increased fuel consumption due to active regeneration of CDPF or LNT, expressed in g / h; ΔQ′ fuel The fuel consumption rate increased by delaying the injection advance angle, expressed in g / h.

[0077] ΔQ″ fuel The specific formula is as follows:

[0078]

[0079] The reduction of PM, NO2, and NO each requires a certain amount of fuel consumption, with ratios c, respectively. PM and For the original NO2 mass flow rate and NO mass flow rate of the engine, Q PM This refers to the engine's original PM mass flow rate.

[0080] k1 characterizes the oxidation rate of PM and is related to NO2 emissions, PM carbon loading in CDPF, and CDPF temperature, as shown below:

[0081]

[0082] k2 characterizes the NO2 reduction rate and is related to the NO2 flow rate in the LNT, the current NO2 reduction rate, the PM carbon loading in the LNT, and the LNT temperature, as shown below:

[0083]

[0084] The above method for selecting the engine operating point that takes into account both LNT and injection advance angle includes the following steps:

[0085] S1: Determine the target output torque of the transmission at the operating point;

[0086] S2: Adjust the carbon loading of CDPF to the current carbon loading of CDPF;

[0087] S3: Adjust the torque of the engine and the torque of the motor so that the torque distribution of the engine and the motor meets the target output torque of the transmission at the operating point, obtain multiple candidate operating points of the engine, and combine different candidate operating points.

[0088] S4: Obtain the current PM oxidation rate after DOC, NO2 displacement, PM carbon load in CDPF, CDPF temperature, NO2 flow rate in LNT, current NO2 reduction rate, PM carbon load in LNT, and LNT temperature. Calculate the average system effective fuel consumption rate for each combination, obtain the optimal combination with the minimum average system effective fuel consumption rate, and use the candidate operating point of the optimal combination as the current engine optimal operating point that takes into account both CDPF and LNT.

[0089] This embodiment also provides an engine operating point adjustment method that takes into account both LNT and injection advance angle, including an operating condition table establishment stage and an operating condition table application stage;

[0090] The process for creating the operating condition table is as follows:

[0091] Multiple operating points are determined during the operation of the hybrid vehicle. The optimal engine operating point for each operating point is obtained under different conditions that take into account CDPF, LNT and injection advance angle and written into the operating point table. The optimal engine operating point is obtained based on the engine operating point selection method that takes into account LNT and injection advance angle as described in any of claims 1-6.

[0092] The process of creating a work status table includes the following steps:

[0093] T1: Determine the carbon load of CDPF, nitrogen displacement of LNT, and injection advance angle; determine the vehicle speed and transmission output torque at a certain operating point.

[0094] T2: Adjust the engine torque and the motor torque, calculate the engine's optimal operating point under the current CDPF carbon load, LNT nitrogen displacement and injection advance angle, and write it into the operating condition table.

[0095] T3: Keep the vehicle speed constant, change the target output torque of the transmission to obtain a new operating point, repeat steps T2-T3 until the optimal engine operating point under the current CDPF carbon load, LNT nitrogen displacement and injection advance angle is obtained at all operating points at the vehicle speed, and write it into the operating point table.

[0096] T4: Change the vehicle speed to obtain a new operating point. Repeat steps T2-T4 until the optimal engine operating point is obtained for all operating points under the current CDPF carbon load, LNT nitrogen displacement and injection advance angle. Write the operating point table.

[0097] T5: Adjust CDPF carbon load and LNT nitrogen displacement, determine the vehicle speed and transmission output torque at a certain operating point, repeat steps T2-T5 until the optimal engine operating point is obtained for all operating points under different CDPF carbon load, LNT nitrogen displacement and injection advance angle, and write it into the operating condition table.

[0098] The application phase of the operating condition table is as follows:

[0099] The system acquires the current PM oxidation rate, NO2 emission, PM carbon load in CDPF, CDPF temperature, NO2 flow rate in LNT, current NO2 reduction rate, PM carbon load in LNT, LNT temperature, and injection advance angle. It then determines the current CDPF carbon load and LNT nitrogen emission. Based on the operating condition table, current vehicle speed, current transmission target output torque, and the current CDPF carbon load, LNT nitrogen emission, and injection advance angle, it obtains and applies the engine's optimal operating point.

[0100] The specific application phase of the operating condition table is as follows:

[0101] Write the operating condition table into the controller of the hybrid vehicle;

[0102] The system obtains the SOC of the power battery, the current vehicle speed, and the current target output torque of the transmission for the hybrid electric vehicle. It determines the current carbon load of the CDPF based on the cumulative reduction of carbon load and the cumulative fuel consumption, determines the current nitrogen emission of the LNT based on the cumulative reduction of NOx mass and the cumulative fuel consumption, and determines the increase in fuel consumption caused by delaying the injection advance angle.

[0103] If the SOC value of the power battery is within the preset threshold range, find the operating point in the operating condition table that is closest to the current vehicle speed and the current transmission target output torque, find the engine's optimal operating point under the current CDPF carbon load, LNT nitrogen displacement and injection advance angle, and apply it.

[0104] If the SOC value of the power battery is not within the preset threshold range, find the operating point in the operating condition table that is closest to the current vehicle speed and the current transmission target output torque. Using the engine's optimal operating point at the current CDPF carbon load, LNT nitrogen displacement and injection advance angle as the benchmark, increase or decrease the effective engine power used to charge the power battery by proportionally using the difference between the power battery SOC and the threshold range, and obtain the engine's optimal operating point and apply it.

[0105] Example 2

[0106] This embodiment provides a method for selecting the engine operating point that takes into account both LNT (Low Noise Level) and injection advance angle. The specific process is as follows:

[0107] Assuming the engine speed is constant at any given moment, only the engine torque can be adjusted. When the motor is not operating, the target charge / discharge of the power battery is 0kW, and the engine's default operating point is A. Figure 1 As shown. B is a candidate engine point in the system charging mode, and C is a candidate engine point in the system discharging mode. For the charging mode, the energy used for driving and the energy ultimately stored in the battery are considered as effective energy. For candidate point B, the effective output power of the engine is P. B The engine's effective system output power is P' B ,

[0108] P B =P A +ΔP AB (0.1)

[0109] P A : The effective output power of the engine at the default operating point A;

[0110] P B: The effective output power of the engine at candidate operating point B;

[0111] ΔP AB The effective output power portion of the engine used for charging;

[0112]

[0113] Q fuel_B : Engine fuel consumption rate at candidate operating point B, in g / h;

[0114] be B : The effective fuel consumption rate of the engine at candidate operating point B, in g / kWh;

[0115] P Chg =η Gen η Chg ΔP AB (0.3)

[0116] η Gen The power generation efficiency of the motor;

[0117] η Chg Battery efficiency during the charging process;

[0118] P Chg : The power that can effectively charge the battery;

[0119] P B ′=P A +P Chg (0.4)

[0120] P' B The effective output power of the engine at candidate operating point B;

[0121]

[0122] be' B : The system effective fuel consumption rate of the engine at candidate operating point B, in g / kWh;

[0123] be′ B >be B (0.6)

[0124] P C =P A -ΔP AC (0.7)

[0125] P C : The effective output power of the engine at candidate operating point C;

[0126] ΔP ACThe portion of the effective output power of the engine that is replaced by the electric motor;

[0127]

[0128] Q fuel_C : Engine fuel consumption rate at candidate operating point C, in g / h;

[0129] be C : The effective fuel consumption rate of the engine at candidate operating point C, expressed in g / kWh;

[0130]

[0131] η Mot : The assist efficiency of the motor;

[0132] η Dchg Battery efficiency during the battery discharge process;

[0133] P Dchg The power of battery discharge;

[0134] P C ′=P A -P Dchg (0.10)

[0135] P' C : The effective output power of the engine system at candidate operating point C;

[0136]

[0137] be' C : The system effective fuel consumption rate of the engine at candidate operating point C, in g / kWh;

[0138] be′ C >be C (0.12)

[0139] like Figure 2 The figure shows the effect of injection ignition angle on fuel consumption, NOx emissions, PM emissions, and noise of a commercial vehicle diesel engine at 1300 rpm, 50% load, and without EGR. Figure 2The three different injection advance angles shown in the diagram, black, red, and blue, correspond to injection advance angles of -6CA, 0CA, and 8CA, respectively. At this operating point, retarding the injection advance angle leads to an increase in specific fuel consumption and a decrease in NOx emissions. PM emissions initially decrease and then increase. This operating condition illustrates a trade-off often encountered when selecting energy-saving and emission-reduction measures and parameters for diesel engines: without an after-treatment system, it is difficult to simultaneously reduce NOx and PM emissions through engine control alone. However, there are exceptions under some low-load conditions, where decreasing the injection advance angle also reduces PM emissions. This is because the decrease in combustion chamber temperature inhibits PM formation. Under these low-load conditions, retarding the injection advance angle can simultaneously reduce PM and NOx emissions. Figure 2 The figure shows the curves of injection advance angle versus cylinder pressure and heat release during combustion. When the injection advance angle is -6.5CA, the maximum cylinder pressure is greater than when the injection advance angle is 0.4CA or 7.3CA. The crankshaft angle (Kurbelwinkel) between the piston and top dead center when the injector begins injection is called the injection advance angle (Spritzbeginn).

[0140] PM and NOx are converted into fuel consumption according to their respective equivalent coefficients, as shown in Equation 0.13.

[0141]

[0142] Equation 0.13 primarily addresses normal operating conditions and the passive regeneration of the CDPF. Building upon this, it is extended to the LNT regeneration condition, regenerating the LNT by changing the injection advance angle. As shown in Equation 0.14, term 4 represents the fuel consumption increase caused by retarding the injection advance angle. Furthermore, in terms 1-3, Q... PM and Q NOx There have also been some changes. Compared with Patent 2, which was only a function of engine torque and engine speed, in this patent it has become a function of engine torque, engine speed and engine injection advance angle.

[0143]

[0144] The final equivalent fuel consumption increment is shown in Equation 0.15.

[0145] ΔQ′ f ′ uel =ΔQ fuel +ΔQ′ fuel (0.15)

[0146] Furthermore, it's important to note the difference between LNT and CDPF regeneration. LNT regeneration requires a reducing agent, generated through incomplete combustion of fuel. Depending on operating conditions, the LNT adsorption process typically lasts 30-300 seconds, followed by a regeneration process of 2-10 seconds, alternating between adsorption and regeneration. Since LNT use usually increases fuel consumption by 1.2-2%, it has a relatively clear relationship with fuel consumption. CDPF active regeneration, on the other hand, requires sufficient temperature to induce PM oxidation at a sufficiently fast rate. The oxidants, NO2 and O2, do not need to be generated through fuel. Therefore, CDPF regeneration is not directly related to fuel consumption, and its equivalent fuel efficiency is determined by the efficiency of the actual strategy. Thus, Equation 0.15 can be adjusted, where β represents the LNT adsorption saturation level. When β equals 0, the original strategy remains unaffected. However, when β is saturated, active LNT regeneration must be performed without considering PM emissions, avoiding situations where optimization based on performance indicators yields no solution. When 0 < β < 1, the impact of PM on fuel economy is adjusted by 1-β, so that the system can find a high-efficiency operating point to regenerate LNT before LNT saturation, instead of having to regenerate it after LNT is completely saturated.

[0147]

[0148] Q′ fuel =Q fuel +ΔQ′ f ′ uel (0.17)

[0149] The fuel consumption rate of the diesel engine at this operating point, in g / kWh, is calculated as shown in Equation 0.18 after adjusting for the effects of exhaust aftertreatment.

[0150]

[0151] When considering the effective fuel consumption rate of the diesel hybrid system at this operating point, rather than the fuel consumption rate of the diesel engine itself, the effective power of the system is calculated according to equations 0.4 and 0.10, and the effective fuel consumption rate of the system is calculated according to equation 0.19.

[0152]

[0153] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in the present invention, and these modifications or substitutions should all be covered within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for selecting the engine operating point that takes into account both LNT (Low Noise Level) and injection advance angle, characterized in that, Hybrid electric vehicles operate under multiple different conditions, each with its own candidate engine operating point. For a given operating point, the following parameters are considered: current PM oxidation rate, NO2 displacement, PM carbon load in the CDPF (Concentrated Dioxide Powder), CDPF temperature, NO2 flow rate in the LNT (Low-Noise Reduction Unit), current NO2 reduction rate, PM carbon load in the LNT, LNT temperature, and fuel consumption increment due to delayed injection advance angle. The average system effective fuel consumption rate is then calculated for each candidate engine operating point under these parameters. The candidate operating point with the lowest average system effective fuel consumption rate is selected as the optimal engine operating point, balancing CDPF regeneration timing with LNT and injection advance angle control. The calculation formula is as follows: in, This indicates that the candidate operating point takes into account the oxidation rate of PM, NO2 emission, PM carbon load in CDPF, CDPF temperature, NO2 flow rate in LNT, current NO2 reduction rate, PM carbon load in LNT, LNT temperature, and the system's effective fuel consumption rate after considering the fuel consumption increase caused by retarding the injection advance angle. This represents the fuel consumption rate at the candidate operating point under the following conditions: PM oxidation rate, NO2 emission rate, PM carbon load in CDPF, CDPF temperature, NO2 flow rate in LNT, current NO2 reduction rate, PM carbon load in LNT, LNT temperature, and injection advance angle. This indicates the system effective output power of the engine at the candidate operating point, taking into account energy conversion losses, active regeneration of CDPF and LNT, and exhaust aftertreatment. in The formula is as follows: When the charging and discharging power of the power battery is at the charging level, The formula is: in, This indicates the effective output power of the power battery when its charging and discharging power is 0kW. P Chg Indicates the effective charging power of the battery; When the charging and discharging power of the power battery is at the discharge level, The formula is: in, P Dchg Indicates the power of battery discharge; in, The formula is as follows: in, This indicates the overall fuel consumption rate of the engine at a candidate operating point, expressed in g / h. The fuel consumption rate increased by CDPF or LNT active regeneration and retarding injection advance angle, expressed in g / h; The formula is as follows: in, The fuel consumption rate of the fuel added for active regeneration of CDPF or LNT, expressed in g / h; The fuel consumption rate increased by delaying the injection advance angle, expressed in g / h; The specific formula is as follows: The reduction of PM, NO2, and NO each requires a certain amount of fuel consumption, with the following ratios: and ; The original NO2 mass flow rate and NO mass flow rate of the engine, This refers to the engine's original PM mass flow rate. Characterizing the oxidation rate of PM, Characterizes the reduction rate of NO2.

2. The engine operating point selection method that takes into account both LNT and injection advance angle as described in claim 1, characterized in that, The relationship is related to NO2 emissions, PM carbon loading in CDPF, and CDPF temperature, as shown below: 。 3. The engine operating point selection method that takes into account both LNT and injection advance angle as described in claim 1, characterized in that, The factors are related to the NO2 flow rate in the LNT, the PM carbon loading in the LNT, and the temperature of the LNT, as shown below: 。 4. The engine operating point selection method that takes into account both LNT and injection advance angle as described in claim 1, characterized in that, Includes the following steps: S1: Determine the target output torque of the transmission at the operating point; S2: Adjust the carbon loading of CDPF to the current carbon loading of CDPF; S3: Adjust the torque of the engine and the torque of the motor so that the torque distribution of the engine and the motor meets the target output torque of the transmission at the operating point, obtain multiple candidate operating points of the engine, and combine different candidate operating points. S4: Obtain the current PM oxidation rate after DOC, NO2 displacement, PM carbon load in CDPF, CDPF temperature, NO2 flow rate in LNT, current NO2 reduction rate, PM carbon load in LNT, and LNT temperature. Calculate the average system effective fuel consumption rate for each combination, obtain the optimal combination with the minimum average system effective fuel consumption rate, and use the candidate operating point of the optimal combination as the current engine optimal operating point that takes into account both CDPF and LNT.

5. A method for adjusting the engine operating point that takes into account both LNT (Low Noise Level) and injection advance angle, characterized in that, This includes the work condition table creation phase and the work condition table application phase; The process for creating the operating condition table is as follows: Multiple operating points are determined during the operation of the hybrid vehicle. The optimal engine operating point for each operating point is obtained under different conditions that take into account CDPF, LNT and injection advance angle and written into the operating point table. The optimal engine operating point is obtained based on the engine operating point selection method that takes into account LNT and injection advance angle as described in any of claims 1-4.

6. The engine operating point adjustment method that takes into account both LNT and injection advance angle according to claim 5, characterized in that, The process of creating a work status table includes the following steps: T1: Determine the carbon load of CDPF, nitrogen displacement of LNT, and injection advance angle; determine the vehicle speed and transmission output torque at a certain operating point. T2: Adjust the engine torque and the motor torque, calculate the engine's optimal operating point under the current CDPF carbon load, LNT nitrogen displacement and injection advance angle, and write it into the operating condition table. T3: Keep the vehicle speed constant, change the target output torque of the transmission to obtain a new operating point, repeat steps T2-T3 until the optimal engine operating point under the current CDPF carbon load, LNT nitrogen displacement and injection advance angle is obtained at all operating points at the vehicle speed, and write it into the operating point table. T4: Change the vehicle speed to obtain a new operating point. Repeat steps T2-T4 until the optimal engine operating point is obtained for all operating points under the current CDPF carbon load, LNT nitrogen displacement and injection advance angle. Write the operating point table. T5: Adjust CDPF carbon load and LNT nitrogen displacement, determine the vehicle speed and transmission output torque at a certain operating point, repeat steps T2-T5 until the optimal engine operating point is obtained for all operating points under different CDPF carbon load, LNT nitrogen displacement and injection advance angle, and write it into the operating condition table.

7. The engine operating point adjustment method that takes into account both LNT and injection advance angle according to claim 5, characterized in that, The application phase of the operating condition table is as follows: The system acquires the current PM oxidation rate, NO2 emission, PM carbon load in CDPF, CDPF temperature, NO2 flow rate in LNT, current NO2 reduction rate, PM carbon load in LNT, LNT temperature, and injection advance angle. It then determines the current CDPF carbon load and LNT nitrogen emission. Based on the operating condition table, current vehicle speed, current transmission target output torque, and the current CDPF carbon load, LNT nitrogen emission, and injection advance angle, it obtains and applies the engine's optimal operating point.

8. The engine operating point adjustment method that takes into account both LNT and injection advance angle according to claim 7, characterized in that, The specific application phase of the operating condition table is as follows: Write the operating condition table into the controller of the hybrid vehicle; The system obtains the SOC of the power battery, the current vehicle speed, and the current target output torque of the transmission for the hybrid electric vehicle. It determines the current carbon load of the CDPF based on the cumulative reduction of carbon load and the cumulative fuel consumption, determines the current nitrogen emission of the LNT based on the cumulative reduction of NOx mass and the cumulative fuel consumption, and determines the increase in fuel consumption caused by delaying the injection advance angle. If the SOC value of the power battery is within the preset threshold range, find the operating point in the operating condition table that is closest to the current vehicle speed and the current transmission target output torque, find the engine's optimal operating point under the current CDPF carbon load, LNT nitrogen displacement and injection advance angle, and apply it. If the SOC value of the power battery is not within the preset threshold range, find the operating point in the operating condition table that is closest to the current vehicle speed and the current transmission target output torque. Using the engine's optimal operating point at the current CDPF carbon load, LNT nitrogen displacement and injection advance angle as the benchmark, increase or decrease the effective engine power used to charge the power battery by proportionally using the difference between the power battery SOC and the threshold range, and obtain the engine's optimal operating point and apply it.

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