A method and device for controlling exhaust back pressure of an engine

Abstract

This invention provides a method and apparatus for controlling exhaust back pressure in an engine, comprising: acquiring the maximum allowable exhaust back pressure of the engine and acquiring the actual exhaust back pressure of the engine; comparing the magnitude between the maximum exhaust back pressure and the actual exhaust back pressure; when the actual exhaust back pressure exceeds the maximum exhaust back pressure, calculating a first maximum allowable boost pressure of the engine based on the maximum exhaust back pressure; calculating a maximum allowable charging efficiency of the engine based on the first maximum boost pressure, and controlling the charging efficiency of the engine based on the maximum charging efficiency. This invention can reduce the risk of exhaust back pressure in the engine exceeding the maximum theoretical design threshold, effectively protecting engine components.

Description

Technical Field

[0001] This invention relates to the field of vehicle system control technology, and in particular to a method and device for controlling the exhaust back pressure of an engine. Background Technology

[0002] With the rapid development of the automobile and internal combustion engine industries, energy demand and environmental protection have become challenges faced by countries around the world. Therefore, energy conservation and emission reduction have become the two major themes of the internal combustion engine industry.

[0003] Currently, to further improve the fuel economy of traditional engines, Miller cycle technology is widely used by domestic and foreign automakers in their next-generation engines. The Miller cycle, through early intake valve closing, effectively reduces pumping losses under medium and low loads, improving the combustion efficiency of traditional engines. Although Miller cycle engines offer high fuel economy, their power performance under low-speed, high-load conditions directly depends on the turbocharger's performance. Therefore, in recent years, VGT (Variable Geometry Turbocharger) technology has been increasingly widely applied to Miller cycle engines. While variable geometry turbochargers can effectively improve torque response time and fuel economy, they cause drastic changes in exhaust back pressure during dynamic boosting. Especially in Miller cycle engines, due to the significantly increased high overlap angle operating range, the impact of exhaust back pressure on residual exhaust gas calculations, and consequently on the accuracy of charging and torque calculations, is greatly amplified. To ensure engine stability and meet increasingly stringent emission regulations, more and more domestic and foreign OEMs are introducing exhaust back pressure sensors into their next-generation engines.

[0004] However, the VGT system causes drastic changes in exhaust back pressure during dynamic boosting, with a significant increase in transient peak pressure. Especially under conditions such as increased external characteristic range, increased GPF carbon loading, or catalytic converter sintering and blockage, there is a risk that the exhaust back pressure may exceed the maximum theoretical design threshold. Summary of the Invention

[0005] This invention provides a method and apparatus for controlling the exhaust back pressure of an engine, in order to solve the above-mentioned problems.

[0006] This invention provides a method for controlling exhaust back pressure in an engine, comprising:

[0007] Obtain the maximum allowable exhaust back pressure of the engine, and obtain the actual exhaust back pressure of the engine;

[0008] Compare the magnitude between the maximum exhaust back pressure and the actual exhaust back pressure;

[0009] When the actual exhaust back pressure exceeds the maximum exhaust back pressure, the first maximum allowable boost pressure of the engine is calculated based on the maximum exhaust back pressure.

[0010] The maximum allowable charging efficiency of the engine is calculated based on the first maximum boost pressure, and the charging efficiency of the engine is controlled based on the maximum charging efficiency.

[0011] According to the present invention, an exhaust back pressure control method for an engine further includes:

[0012] The second maximum boost pressure is obtained by performing feedback control calculations based on the maximum exhaust back pressure and the actual exhaust back pressure.

[0013] Accordingly, the step of calculating the maximum allowable charging efficiency of the engine based on the first maximum boost pressure, and controlling the charging efficiency of the engine based on the maximum charging efficiency, includes:

[0014] The maximum allowable charging efficiency of the engine is calculated based on the first maximum boost pressure and the second maximum boost pressure, and the charging efficiency of the engine is controlled based on the maximum charging efficiency.

[0015] According to the present invention, an exhaust back pressure control method for an engine, wherein the step of performing feedback control calculation based on the maximum exhaust back pressure and the actual exhaust back pressure to obtain a second maximum boost pressure includes:

[0016] The difference between the maximum exhaust back pressure and the actual exhaust back pressure is obtained as the exhaust back pressure difference.

[0017] Calculate the product of the feedback control P-term coefficient and the exhaust back pressure difference, and use the product result as the first feedback value;

[0018] The exhaust back pressure difference is integrated, and the product of the integrated result and the feedback control integral coefficient is used as the second feedback value.

[0019] The sum of the first feedback value and the second feedback value is taken as the second maximum boost pressure.

[0020] According to the present invention, an exhaust back pressure control method for an engine, wherein calculating the first maximum allowable boost pressure of the engine based on the maximum exhaust back pressure includes:

[0021] The maximum turbine power is calculated based on the maximum exhaust back pressure and using the turbine power calculation method.

[0022] The turbine's state information is obtained, and based on the state information and the maximum turbine power, the maximum compression power is calculated using an energy power balance calculation method.

[0023] The gas flow rate through the compressor and the pressure and temperature upstream of the compressor are obtained. Based on the gas flow rate through the compressor, the pressure and temperature upstream of the compressor, and the maximum compression power, the maximum downstream pressure of the compressor is calculated using the centrifugal compression process balance calculation method.

[0024] The gas flow rate through the intercooler and the gas temperature upstream of the intercooler are obtained. Based on the gas flow rate through the intercooler, the gas temperature upstream of the intercooler, and the pressure downstream of the maximum compressor, the first maximum boost pressure is calculated using a pressure drop calculation method.

[0025] According to the present invention, an exhaust back pressure control method for an engine is provided, wherein the turbine power calculation method is as follows:

[0026]

[0027] In the formula, Maximum turbine power; T3 is the turbine flow rate; T3 is the upstream gas temperature of the turbine; η trb For turbine efficiency; c p，exh p3 represents the exhaust specific heat capacity; p4 represents the turbine downstream pressure; p3,max represents the maximum exhaust back pressure; κ represents the maximum exhaust back pressure. exh The ideal gas adiabatic index is the exhaust gas.

[0028] According to the present invention, an exhaust back pressure control method for an engine is provided, wherein the energy power balance calculation method is as follows:

[0029]

[0030] In the formula, Maximum turbine power; P is the maximum compression power. kin P is the turbocharger's rotational power. fric Frictional power; Itc is the turbocharger's moment of inertia; ω tc The angular velocity of the turbine rotation; M is the angular acceleration of the turbine rotation. fric This refers to the frictional torque of the turbocharger.

[0031] According to the exhaust back pressure control method for an engine provided by the present invention, the centrifugal compression process balance calculation method is as follows:

[0032]

[0033] In the formula, This represents the maximum downstream pressure of the compressor. Maximum compression power; T1 is the gas flow rate through the compressor; T1 is the gas temperature upstream of the compressor; η cmpr For compressor efficiency; c p，cmpr κ represents the specific heat capacity of the intake air; p1 represents the pressure upstream of the compressor; and κ represents the adiabatic index of the ideal intake gas.

[0034] According to the exhaust back pressure control method for an engine provided by the present invention, the centrifugal compression process balance calculation method is as follows:

[0035]

[0036] Mode, The first maximum boost pressure; T 20 This refers to the gas temperature upstream of the intercooler; Δp is the gas flow rate through the intercooler. ico This is the pressure drop generated when the gas passes through the intake intercooler.

[0037] According to a method for controlling exhaust back pressure of an engine provided by the present invention, the step of calculating the maximum allowable charging efficiency of the engine based on the first maximum boost pressure and the second maximum boost pressure, and controlling the charging efficiency of the engine based on the maximum charging efficiency, includes:

[0038] The total maximum boost pressure is calculated based on the first maximum boost pressure and the second maximum boost pressure;

[0039] The partial pressure of residual exhaust gas in the cylinder and the inflation slope are obtained. Based on the partial pressure of residual exhaust gas in the cylinder, the inflation slope, and the total maximum boost pressure, the maximum inflation efficiency is calculated.

[0040]

[0041] In the formula, rl p3，max For maximum inflation efficiency; p res fac is the partial pressure of residual exhaust gas in the cylinder; chrg The inflation slope;

[0042] rl des =min(rl) trqstrc， rl p3，max )

[0043] Compare maximum inflation efficiency rl p3，max The target inflation efficiency rl calculated based on the target torque requirement trastrcThe values ​​between the two values ​​are used to determine the target inflation efficiency rl to be applied. des Based on the target inflation efficiency rl to be applied des Control the engine's charging efficiency.

[0044] The present invention also provides an exhaust back pressure control device for an engine, comprising:

[0045] The exhaust back pressure acquisition module is used to acquire the maximum allowable exhaust back pressure of the engine and the actual exhaust back pressure of the engine.

[0046] An exhaust back pressure comparison module is used to compare the magnitude between the maximum exhaust back pressure and the actual exhaust back pressure;

[0047] The first maximum boost pressure calculation module is used to calculate the first maximum boost pressure allowed by the engine based on the maximum exhaust back pressure when the actual exhaust back pressure exceeds the maximum exhaust back pressure.

[0048] The inflation efficiency control module is used to calculate the maximum inflation efficiency allowed by the engine based on the first maximum boost pressure, and to control the inflation efficiency of the engine based on the maximum inflation efficiency.

[0049] The present invention also provides an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement the exhaust back pressure control method of any of the above-described engines.

[0050] The present invention also provides a non-transitory computer-readable storage medium having a computer program stored thereon, wherein the computer program, when executed by a processor, implements the exhaust back pressure control method of any of the above-described engines.

[0051] The exhaust back pressure control method and apparatus for an engine provided by the present invention calculates a first maximum allowable boost pressure for the engine based on the maximum exhaust back pressure when the actual exhaust back pressure exceeds the maximum exhaust back pressure; calculates the maximum allowable charging efficiency for the engine based on the first maximum boost pressure; and controls the charging efficiency of the engine based on the maximum charging efficiency. This supplements the boost control logic in the current engine control system, reduces the risk of exhaust back pressure exceeding the maximum theoretical design threshold in the turbocharger system, and effectively protects the system components. Attached Figure Description

[0052] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0053] Figure 1 This is a schematic diagram of the existing VGT boost control logic;

[0054] Figure 2 This is a schematic diagram of the VGT boost control logic provided in an embodiment of the present invention;

[0055] Figure 3 This is a flowchart illustrating the exhaust back pressure control method for an engine provided in an embodiment of the present invention. Figure 1 ;

[0056] Figure 4 This is a flowchart illustrating the exhaust back pressure control method for an engine provided in an embodiment of the present invention. Figure 2 ;

[0057] Figure 5 This is a structural block diagram of the exhaust back pressure control device for an engine provided in an embodiment of the present invention;

[0058] Figure 6 This is a schematic diagram of the physical structure of an electronic device provided in an embodiment of the present invention. Detailed Implementation

[0059] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this 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 this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0060] In the prior art, the VGT boost control logic is as follows: Figure 1 As shown, it calculates the target boost pressure based solely on the charging efficiency required by the engine torque; then, it adjusts the VGT nozzle ring opening through hierarchical control to achieve the desired target boost pressure; however, it does not consider the system's limitation on maximum exhaust back pressure. Therefore, this invention introduces a maximum exhaust back pressure protection strategy for the engine as a supplement to the current boost control logic. Specifically, as follows... Figure 2As shown, this invention incorporates a maximum exhaust back pressure protection strategy between the torque-demand-based inflation efficiency and the target boost pressure based on the required inflation volume. This maximum exhaust back pressure protection strategy controls the subsequent target boost pressure based on the torque-demand-based inflation efficiency and the actual exhaust back pressure. The maximum exhaust back pressure protection strategy is described in detail below with reference to the accompanying drawings.

[0061] Figure 3 This is a flowchart illustrating the exhaust back pressure control method for an engine provided in an embodiment of the present invention. Figure 1 ; Figure 4 This is a flowchart illustrating the exhaust back pressure control method for an engine provided in an embodiment of the present invention. Figure 2 ;like Figure 3 As shown in Figure 4, an exhaust back pressure control method for an engine includes the following steps:

[0062] S101, obtain the maximum allowable exhaust back pressure of the engine, and obtain the actual exhaust back pressure of the engine.

[0063] In this step, the maximum allowable exhaust back pressure for the current engine operating conditions is calculated based on the requirements of each engine subsystem (e.g., turbocharging system, aftertreatment system, etc.). Specifically, VTG turbocharger products have requirements for maximum exhaust back pressure (component protection); in addition, excessively high exhaust back pressure over a prolonged period may cause loosening or displacement of exhaust system components (e.g., GPF) mounting mechanisms; excessive back pressure may occur due to engine external characteristics and dynamic operating conditions; increased carbon load in the GPF may cause VGT back pressure to exceed normal levels; and high exhaust back pressure may occur due to fault conditions such as catalytic converter sintering and blockage, among other subsystem requirements for exhaust back pressure.

[0064] In addition, the maximum exhaust back pressure is generally obtained through MAP calibration based on the protection requirements of each component.

[0065] The actual exhaust back pressure is measured by the exhaust back pressure sensor.

[0066] S102, compare the magnitude between the maximum exhaust back pressure and the actual exhaust back pressure.

[0067] In this step, the maximum exhaust back pressure is compared with the actual exhaust back pressure to determine whether to enter the maximum exhaust back pressure protection strategy (i.e., the subsequent calculation process based on the maximum exhaust back pressure). When the actual exhaust back pressure exceeds the maximum exhaust back pressure, proceed to step S103; when the actual exhaust back pressure does not exceed the maximum exhaust back pressure, directly obtain the inflation efficiency based on the torque requirement, and calculate the target boost pressure based on the inflation efficiency based on the torque requirement.

[0068] S103, when the actual exhaust back pressure exceeds the maximum exhaust back pressure, calculate the first maximum boost pressure allowed by the engine based on the maximum exhaust back pressure.

[0069] In this step, if the actual exhaust back pressure exceeds the maximum exhaust back pressure, it indicates that there is a risk that the exhaust back pressure exceeds the maximum theoretical design threshold. At this time, a maximum exhaust back pressure protection strategy needs to be introduced, that is, the boost pressure needs to be calculated based on the maximum exhaust back pressure.

[0070] Here, the first maximum boost pressure is calculated using a physical model, and details are described below.

[0071] S104, calculate the maximum allowable charging efficiency of the engine based on the first maximum boost pressure, and control the charging efficiency of the engine based on the maximum charging efficiency.

[0072] In this step, after calculating the maximum inflation efficiency based on the first maximum boost pressure, it is determined whether the maximum inflation efficiency exceeds the inflation efficiency based on torque requirements. If the inflation efficiency based on torque requirements exceeds the inflation efficiency corresponding to the maximum permissible exhaust back pressure, then the inflation efficiency based on torque requirements needs to be limited. The value used for the limitation is the inflation efficiency corresponding to the maximum permissible exhaust back pressure, and the exhaust back pressure is controlled based on this limit value.

[0073] This invention provides an exhaust back pressure control method for an engine. When the actual exhaust back pressure exceeds the maximum exhaust back pressure, a first maximum allowable boost pressure is calculated based on the maximum exhaust back pressure. The maximum allowable charging efficiency is then calculated based on the first maximum boost pressure, and the engine's charging efficiency is controlled based on this maximum charging efficiency. This method supplements the boost control logic in the current engine control system, reduces the risk of exhaust back pressure exceeding the maximum theoretical design threshold in turbocharged systems, and effectively protects system components.

[0074] Furthermore, the method also includes:

[0075] The second maximum boost pressure is obtained by performing feedback control calculations based on the maximum exhaust back pressure and the actual exhaust back pressure.

[0076] Accordingly, the step of calculating the maximum allowable charging efficiency of the engine based on the first maximum boost pressure and controlling the charging efficiency of the engine based on the maximum charging efficiency includes:

[0077] The maximum allowable charging efficiency of the engine is calculated based on the first maximum boost pressure and the second maximum boost pressure, and the charging efficiency of the engine is controlled based on the maximum charging efficiency.

[0078] Since the first maximum boost pressure is calculated entirely based on a physical model, its accuracy is directly affected by the deviation of the physical model itself or the accuracy of the sensors used in the physical model. To improve the robustness of the maximum exhaust back pressure protection strategy, this embodiment incorporates a second maximum boost pressure, calculated based on the difference between the maximum and actual exhaust back pressure, as feedback control, while using the first maximum boost pressure as feedforward control. The specific calculation process for the second maximum boost pressure is detailed below.

[0079] The present invention provides an exhaust back pressure control method for an engine, which reduces the influence of sensor accuracy and model accuracy on the calculated boost pressure by using a first maximum boost pressure as feedforward control and a second maximum boost pressure as feedback control, and improves the robustness of the maximum exhaust back pressure protection strategy.

[0080] Further, the step of calculating the second maximum boost pressure based on the feedback control of the maximum exhaust back pressure and the actual exhaust back pressure includes:

[0081] The difference between the maximum exhaust back pressure and the actual exhaust back pressure is obtained as the exhaust back pressure difference.

[0082] Calculate the product of the feedback control P-term coefficient and the exhaust back pressure difference, and use the product result as the first feedback value.

[0083] The exhaust back pressure difference is integrated, and the product of the integrated result and the feedback control integral coefficient is used as the second feedback value.

[0084] The sum of the first feedback value and the second feedback value is taken as the second maximum boost pressure.

[0085] Specifically, the second maximum boost pressure is calculated using the following formula:

[0086]

[0087] In the formula, The second maximum boost pressure; kP is the coefficient of the feedback control P term; kI is the integral coefficient of the feedback control.

[0088] Further, the calculation of the first maximum allowable boost pressure of the engine based on the maximum exhaust back pressure includes:

[0089] The maximum turbine power is calculated based on the maximum exhaust back pressure and using a turbine power calculation method.

[0090] The method for calculating turbine power is as follows:

[0091]

[0092] In the formula, Maximum turbine power; T3 is the turbine flow rate; T3 is the upstream gas temperature of the turbine; η trb For turbine efficiency; c p，exh p is the exhaust specific heat capacity; p4 is the downstream pressure of the turbine; p 3，max Maximum exhaust back pressure; κ exh The ideal gas adiabatic index is the exhaust gas.

[0093] The turbine's state information is obtained, and based on the state information and the maximum turbine power, the maximum compression power is calculated using an energy power balance calculation method.

[0094] The energy-power balance calculation method is based on the principle that the turbine expansion and compressor compression processes on the same shaft satisfy the energy-power balance principle. Specifically:

[0095]

[0096] In the formula, Maximum turbine power; P is the maximum compression power. kin P is the turbocharger's rotational power. fric For frictional power; I tc ω is the rotational inertia of the turbocharger. tc The angular velocity of the turbine rotation; M is the angular acceleration of the turbine rotation. fric This refers to the turbocharger friction torque. The turbocharger rotational power, friction power, turbocharger moment of inertia, turbine rotational angular velocity, turbine rotational angular acceleration, and turbocharger friction torque are all state information of the turbine.

[0097] The gas flow rate through the compressor and the pressure and temperature upstream of the compressor are obtained. Based on the gas flow rate through the compressor, the pressure and temperature upstream of the compressor, and the maximum compression power, the maximum downstream pressure of the compressor is calculated using a centrifugal compression process balance calculation method.

[0098] The method for calculating the balance of the centrifugal compression process is as follows:

[0099]

[0100] In the formula, This represents the maximum downstream pressure of the compressor. Maximum compression power; T1 is the gas flow rate through the compressor; T1 is the gas temperature upstream of the compressor; η cmpr For compressor efficiency; c p，cmpr κ represents the specific heat capacity of the intake air; p1 represents the pressure upstream of the compressor; and κ represents the adiabatic index of the ideal intake gas.

[0101] The gas flow rate through the intercooler and the gas temperature upstream of the intercooler are obtained. Based on the gas flow rate through the intercooler, the gas temperature upstream of the intercooler, and the pressure downstream of the maximum compressor, the first maximum boost pressure is calculated using a pressure drop calculation method.

[0102] The method for calculating the balance of the centrifugal compression process is as follows:

[0103]

[0104] Mode, The first maximum boost pressure; T 20 This refers to the gas temperature upstream of the intercooler; Δp is the gas flow rate through the intercooler. ico This is the pressure drop generated when the gas passes through the intake intercooler.

[0105] The present invention provides an exhaust back pressure control method for an engine, which calculates the first maximum boost pressure using the physical model described above, thereby greatly reducing the amount of additional calibration work.

[0106] Further, the step of calculating the maximum allowable charging efficiency of the engine based on the first maximum boost pressure and the second maximum boost pressure, and controlling the charging efficiency of the engine based on the maximum charging efficiency, includes:

[0107] The total maximum boost pressure is calculated based on the first maximum boost pressure and the second maximum boost pressure.

[0108] Obtain the partial pressure of the residual exhaust gas in the cylinder and the filling slope. Taking the gas in the cylinder as the research object, based on the ideal gas equation, calculate the maximum filling efficiency according to the partial pressure of the residual exhaust gas in the cylinder, the filling slope, and the total maximum boost pressure.

[0109]

[0110] In the formula, rl p3，max For maximum inflation efficiency; p res fac is the partial pressure of residual exhaust gas in the cylinder; chrgThe inflation slope.

[0111] rl des =min(rl) trqstrc rl p3，max )

[0112] Compare maximum inflation efficiency rl p3，max The target inflation efficiency rl calculated based on the target torque requirement trqstrc The values ​​between the two values ​​are used to determine the target inflation efficiency rl to be applied. des Based on the target inflation efficiency rl to be applied des Control the engine's charging efficiency.

[0113] This invention provides an exhaust back pressure control method for an engine, which controls the maximum charging efficiency by relating it to rl. trqstrc The two values ​​are compared, and the smaller value is taken as the basis for controlling the charging efficiency, thereby avoiding the actual exhaust back pressure from exceeding the maximum exhaust back pressure allowed by the engine system.

[0114] The exhaust back pressure control device for an engine provided by the present invention will be described below. The exhaust back pressure control device for an engine described below can be referred to in correspondence with the exhaust back pressure control method for an engine described above.

[0115] Figure 5 This is a structural block diagram of the exhaust back pressure control device for an engine provided in an embodiment of the present invention, as shown below. Figure 5 As shown, an exhaust back pressure control device for an engine includes:

[0116] The exhaust back pressure acquisition module 501 is used to acquire the maximum allowable exhaust back pressure of the engine and the actual exhaust back pressure of the engine.

[0117] This module calculates the maximum allowable exhaust back pressure under the current engine operating conditions, based on the requirements of each engine subsystem (e.g., turbocharging system, aftertreatment system, etc.). Specifically, VTG turbocharger products have requirements for maximum exhaust back pressure (component protection); in addition, prolonged excessively high exhaust back pressure may cause loosening or displacement of exhaust system components (e.g., GPF) mounting mechanisms; excessive back pressure may occur due to engine external characteristics and dynamic operating conditions; increased carbon load in the GPF may cause VGT back pressure to exceed normal levels; and high exhaust back pressure may occur due to fault conditions such as catalytic converter sintering and blockage, among other subsystem requirements for exhaust back pressure.

[0118] In addition, the maximum exhaust back pressure is generally obtained through MAP calibration based on the protection requirements of each component.

[0119] The actual exhaust back pressure is measured by the exhaust back pressure sensor.

[0120] The exhaust back pressure comparison module 502 is used to compare the magnitude between the maximum exhaust back pressure and the actual exhaust back pressure.

[0121] In this module, the maximum exhaust back pressure is compared with the actual exhaust back pressure to determine whether to enter the maximum exhaust back pressure protection strategy (i.e., the subsequent calculation process based on the maximum exhaust back pressure). When the actual exhaust back pressure exceeds the maximum exhaust back pressure, the first maximum boost pressure calculation module 503 is entered; when the actual exhaust back pressure does not exceed the maximum exhaust back pressure, the inflation efficiency based on torque requirement is directly obtained, and the target boost pressure is calculated based on the inflation efficiency based on torque requirement.

[0122] The first maximum boost pressure calculation module 503 is used to calculate the first maximum boost pressure allowed by the engine based on the maximum exhaust back pressure when the actual exhaust back pressure exceeds the maximum exhaust back pressure.

[0123] In this module, if the actual exhaust back pressure exceeds the maximum exhaust back pressure, it indicates that there is a risk that the exhaust back pressure exceeds the maximum theoretical design threshold. At this time, a maximum exhaust back pressure protection strategy needs to be introduced, that is, the boost pressure needs to be calculated based on the maximum exhaust back pressure.

[0124] Here, the first maximum boost pressure is calculated using a physical model.

[0125] The inflation efficiency control module 504 is used to calculate the maximum inflation efficiency allowed by the engine based on the first maximum boost pressure, and to control the inflation efficiency of the engine based on the maximum inflation efficiency.

[0126] In this module, after calculating the maximum inflation efficiency based on the first maximum boost pressure, it is determined whether the maximum inflation efficiency exceeds the inflation efficiency based on torque requirements. If the inflation efficiency based on torque requirements exceeds the inflation efficiency corresponding to the maximum allowable exhaust back pressure, then the inflation efficiency based on torque requirements needs to be limited. The value used for the limitation is the inflation efficiency corresponding to the maximum allowable exhaust back pressure, and the exhaust back pressure is controlled based on this limit value.

[0127] The exhaust back pressure control device for an engine provided in this embodiment of the invention calculates the first maximum allowable boost pressure of the engine based on the maximum exhaust back pressure when the actual exhaust back pressure exceeds the maximum exhaust back pressure; calculates the maximum allowable charging efficiency of the engine based on the first maximum boost pressure; and controls the charging efficiency of the engine based on the maximum charging efficiency. This supplements the boost control logic in the current engine control system, reduces the risk of exhaust back pressure exceeding the maximum theoretical design threshold in the turbocharger system, and effectively protects the system components.

[0128] Figure 6 This is a schematic diagram of the physical structure of an electronic device provided in an embodiment of the present invention, such as... Figure 6 As shown, the electronic device may include a processor 610, a communication interface 620, a memory 630, and a communication bus 640. The processor 610, communication interface 620, and memory 630 communicate with each other via the communication bus 640. The processor 610 can call logical instructions in the memory 630 to execute an engine exhaust back pressure control method. The engine exhaust back pressure control method includes: obtaining the maximum allowable exhaust back pressure of the engine and obtaining the actual exhaust back pressure of the engine; comparing the maximum exhaust back pressure with the actual exhaust back pressure; if the actual exhaust back pressure exceeds the maximum exhaust back pressure, calculating a first maximum allowable boost pressure of the engine based on the maximum exhaust back pressure; calculating a maximum allowable charging efficiency of the engine based on the first maximum boost pressure, and controlling the engine charging efficiency based on the maximum charging efficiency.

[0129] Furthermore, the logical instructions in the aforementioned memory 630 can be implemented as software functional units and, when sold or used as independent products, can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, or a part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods of the various embodiments of the present invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0130] In another aspect, the present invention also provides a non-transitory computer-readable storage medium storing a computer program thereon, which, when executed by a processor, implements the exhaust back pressure control method for an engine provided by the above method. The exhaust back pressure control method includes: obtaining a maximum allowable exhaust back pressure of the engine and obtaining an actual exhaust back pressure of the engine; comparing the magnitude between the maximum exhaust back pressure and the actual exhaust back pressure; if the actual exhaust back pressure exceeds the maximum exhaust back pressure, calculating a first maximum allowable boost pressure of the engine based on the maximum exhaust back pressure; calculating a maximum allowable charging efficiency of the engine based on the first maximum boost pressure, and controlling the charging efficiency of the engine based on the maximum charging efficiency.

[0131] The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate, and the components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs. Those skilled in the art can understand and implement this without any creative effort.

[0132] Through the above description of the embodiments, those skilled in the art can clearly understand that each embodiment can be implemented by means of software plus necessary general-purpose hardware platforms, and of course, it can also be implemented by hardware. Based on this understanding, the above technical solutions, in essence or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, magnetic disk, optical disk, etc., including several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute the methods of various embodiments or some parts of embodiments.

[0133] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for controlling exhaust back pressure of an engine, characterized in that, include: Obtain the maximum allowable exhaust back pressure of the engine, and obtain the actual exhaust back pressure of the engine; Compare the magnitude between the maximum exhaust back pressure and the actual exhaust back pressure; When the actual exhaust back pressure exceeds the maximum exhaust back pressure, the first maximum allowable boost pressure of the engine is calculated based on the maximum exhaust back pressure. The maximum allowable charging efficiency of the engine is calculated based on the first maximum boost pressure, and the charging efficiency of the engine is controlled based on the maximum charging efficiency. The second maximum boost pressure is obtained by feedback control calculation based on the maximum exhaust back pressure and the actual exhaust back pressure. Accordingly, the step of calculating the maximum allowable charging efficiency of the engine based on the first maximum boost pressure, and controlling the charging efficiency of the engine based on the maximum charging efficiency, includes: The maximum allowable charging efficiency of the engine is calculated based on the first maximum boost pressure and the second maximum boost pressure, and the charging efficiency of the engine is controlled based on the maximum charging efficiency.

2. The exhaust back pressure control method for an engine according to claim 1, characterized in that, The step of calculating the second maximum boost pressure based on the feedback control of the maximum exhaust back pressure and the actual exhaust back pressure includes: The difference between the maximum exhaust back pressure and the actual exhaust back pressure is obtained as the exhaust back pressure difference. Calculate the product of the feedback control P-term coefficient and the exhaust back pressure difference, and use the product result as the first feedback value; The exhaust back pressure difference is integrated, and the product of the integrated result and the feedback control integral coefficient is used as the second feedback value. The sum of the first feedback value and the second feedback value is taken as the second maximum boost pressure.

3. The exhaust back pressure control method for an engine according to claim 1, characterized in that, The calculation of the first maximum allowable boost pressure of the engine based on the maximum exhaust back pressure includes: The maximum turbine power is calculated based on the maximum exhaust back pressure and using the turbine power calculation method. The turbine's state information is obtained, and based on the state information and the maximum turbine power, the maximum compression power is calculated using an energy power balance calculation method. The gas flow rate through the compressor and the pressure and temperature upstream of the compressor are obtained. Based on the gas flow rate through the compressor, the pressure and temperature upstream of the compressor, and the maximum compression power, the maximum downstream pressure of the compressor is calculated using the centrifugal compression process balance calculation method. The gas flow rate through the intercooler and the gas temperature upstream of the intercooler are obtained. Based on the gas flow rate through the intercooler, the gas temperature upstream of the intercooler, and the pressure downstream of the maximum compressor, the first maximum boost pressure is calculated using a pressure drop calculation method.

4. The exhaust back pressure control method for an engine according to claim 3, characterized in that, The method for calculating turbine power is as follows: In the formula, Maximum turbine power; For turbine flow rate; The upstream gas temperature of the turbine; For turbine efficiency; The specific heat capacity of the exhaust gas; This refers to the downstream pressure of the turbine. This represents the maximum exhaust back pressure. The ideal gas adiabatic index is the exhaust gas.

5. The exhaust back pressure control method for an engine according to claim 3, characterized in that, The energy power balance calculation method is as follows: In the formula, Maximum turbine power; Maximum compression power; This refers to the rotational power of the turbocharger. Friction power; The moment of inertia of the turbocharger; The angular velocity of the turbine rotation; This refers to the angular acceleration of the turbine rotation. This refers to the frictional torque of the turbocharger.

6. The exhaust back pressure control method for an engine according to claim 5, characterized in that, The method for calculating the balance of the centrifugal compression process is as follows: In the formula, This represents the maximum downstream pressure of the compressor. Maximum compression power; This refers to the gas flow rate through the compressor. The gas temperature upstream of the compressor; For compressor efficiency; The specific heat capacity of the intake air; The pressure upstream of the compressor; The adiabatic index is the ideal gas for the intake.

7. The exhaust back pressure control method for an engine according to claim 3, characterized in that, The pressure drop calculation method is as follows: In the formula, The first maximum boost pressure; This refers to the gas temperature upstream of the intercooler; This refers to the gas flow rate through the intercooler; This is the pressure drop generated when the gas passes through the intake intercooler; This is the downstream pressure of the maximum compressor.

8. The exhaust back pressure control method for an engine according to any one of claims 1-7, characterized in that, The step of calculating the maximum allowable charging efficiency of the engine based on the first maximum boost pressure and the second maximum boost pressure, and controlling the charging efficiency of the engine based on the maximum charging efficiency, includes: The total maximum boost pressure is calculated based on the first maximum boost pressure and the second maximum boost pressure; The partial pressure of residual exhaust gas in the cylinder and the inflation slope are obtained. Based on the partial pressure of residual exhaust gas in the cylinder, the inflation slope, and the total maximum boost pressure, the maximum inflation efficiency is calculated. In the formula, To maximize inflation efficiency; The partial pressure of residual exhaust gas in the cylinder; The inflation slope; This represents the total maximum boost pressure. Compare maximum inflation efficiency The target inflation efficiency calculated based on the target torque requirement The values ​​between the two values ​​are considered, and the smaller value is taken as the target inflation efficiency to be applied. Based on the target inflation efficiency to be applied Control the engine's charging efficiency.

9. An exhaust back pressure control device for an engine, characterized in that, include: The exhaust back pressure acquisition module is used to acquire the maximum allowable exhaust back pressure of the engine and the actual exhaust back pressure of the engine. An exhaust back pressure comparison module is used to compare the magnitude between the maximum exhaust back pressure and the actual exhaust back pressure; The first maximum boost pressure calculation module is used to calculate the first maximum boost pressure allowed by the engine based on the maximum exhaust back pressure when the actual exhaust back pressure exceeds the maximum exhaust back pressure. The charging efficiency control module is used to calculate the maximum allowable charging efficiency of the engine based on the first maximum boost pressure, and control the charging efficiency of the engine based on the maximum charging efficiency; it is also used to perform feedback control calculation based on the maximum exhaust back pressure and the actual exhaust back pressure to obtain a second maximum boost pressure; correspondingly, the step of calculating the maximum allowable charging efficiency of the engine based on the first maximum boost pressure and controlling the charging efficiency of the engine based on the maximum charging efficiency includes: calculating the maximum allowable charging efficiency of the engine based on the first maximum boost pressure and the second maximum boost pressure, and controlling the charging efficiency of the engine based on the maximum charging efficiency.

10. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the program, it implements the exhaust back pressure control method for the engine as described in any one of claims 1 to 8.

11. A non-transitory computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, it implements the exhaust back pressure control method of the engine as described in any one of claims 1 to 8.

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