CN115437415B - Engine basic boost pressure determining method and engine charging control method - Google Patents

Abstract

The present invention provides a method for determining a basic boost pressure of an engine and a method for controlling an engine charging, comprising: obtaining an initial value of a basic boost pressure and a system state quantity of the engine; calculating a corresponding first exhaust back pressure value and a second exhaust back pressure value using a pre-built turbocharger model and an engine charging model according to the initial value of the basic boost pressure and the system state quantity; judging whether the difference between the first exhaust back pressure value and the second exhaust back pressure value exceeds a preset threshold value; and determining a basic boost pressure value according to the first exhaust back pressure value and the second exhaust back pressure value when the difference between the first exhaust back pressure value and the second exhaust back pressure value does not exceed the preset threshold value, so as to realize intake control. The present invention can reduce unnecessary throttling effects and effectively reduce additional energy losses.

Description

Method for determining basic engine boost pressure and method for controlling engine charging

Technical Field

The present invention relates to the technical field of vehicle system control, and in particular to a method for determining a basic boost pressure of an engine and a method for controlling engine charging.

Background Art

With the rapid development of the automobile and internal combustion engine industries, energy demand and environmental protection issues have become difficult problems faced by countries around the world today. Therefore, energy conservation and emission reduction have become the two major themes of the development of the internal combustion engine industry. How to maximize the power of the engine through engine intake control has become a research hotspot. Specifically, engine intake control consists of two parts: throttle control and boost control. In practical applications, it is necessary to distinguish the application ranges of the two actuators, the throttle and the turbocharger, according to the basic boost pressure; when the target boost pressure corresponding to the target charge volume is less than the basic boost pressure, the throttle control is used to adjust the engine intake volume; otherwise, the boost control will intervene and make the current basic boost pressure reach the required target boost pressure.

However, since the basic boost pressure is directly affected by factors such as the engine working cycle and the type of turbocharger, the boost control is not precise enough. That is, if the basic boost pressure is calculated too small, the boost control will intervene too early, causing the throttle and the supercharger to work at the same time, causing unnecessary throttling effect and causing additional energy loss.

In summary, the current basic boost pressure control method is not accurate enough, easily leads to energy loss, and fails to achieve the goal of energy conservation and emission reduction.

Summary of the invention

The present invention provides a method for determining a basic boost pressure of an engine and a method for controlling an engine charging, so as to solve the above problems.

The present invention provides a method for determining a basic boost pressure of an engine, comprising:

Obtaining the initial value of basic boost pressure and the system state quantity of the engine;

According to the basic boost pressure initial value and the system state quantity, a corresponding first exhaust back pressure value and a corresponding second exhaust back pressure value are calculated using a pre-built turbocharger model and an engine charging model respectively;

determining whether a difference between the first exhaust back pressure value and the second exhaust back pressure value exceeds a preset threshold;

When the difference between the first exhaust back pressure value and the second exhaust back pressure value does not exceed a preset threshold, a basic boost pressure value is determined according to the first exhaust back pressure value and the second exhaust back pressure value to achieve intake control.

According to a method for determining a basic boost pressure of an engine provided by the present invention, after determining whether the difference between the first exhaust back pressure value and the second exhaust back pressure value exceeds a preset threshold, the method further includes:

When the difference between the first exhaust back pressure value and the second exhaust back pressure value exceeds a preset threshold, performing iterative calculation based on the first exhaust back pressure value and the second exhaust back pressure value by using a predefined iterative algorithm, and using the value obtained by the iterative calculation as a new basic boost pressure initial value;

Correspondingly, the first exhaust back pressure value and the second exhaust back pressure value are calculated based on the basic boost pressure initial value and the system state quantity using a pre-built turbocharger model and an engine charging model, respectively, including:

The turbocharger model and the engine charging model respectively calculate the corresponding new first exhaust back pressure value and new second exhaust back pressure value based on the new basic boost pressure initial value and the system state quantity.

According to a method for determining a basic boost pressure of an engine provided by the present invention, the system state quantity includes ambient pressure, current air-fuel ratio, flow through the compressor, gas temperature upstream of the compressor, and gas temperature upstream of the turbine;

Accordingly, according to the basic initial value of the boost pressure and the system state quantity, the first exhaust back pressure value is calculated using a pre-built turbocharger model, including:

Obtaining the compressor upstream pressure according to the ambient pressure and the flow rate passing through the compressor;

Acquire the pressure downstream of the compressor according to the flow rate through the compressor and the initial value of the basic boost pressure;

Based on the centrifugal compression process balance equation, the compressor power is obtained using the compressor upstream gas temperature, the compressor upstream pressure and the compressor downstream pressure;

Based on the energy and power balance principle, the turbine power is determined using the compressor power;

Obtain the exhaust flow rate according to the flow rate through the compressor and the current air-fuel ratio;

When the actuator at the turbine end is in the maximum opening state, based on the adiabatic expansion inside the turbine and the first law of thermodynamics, the first exhaust back pressure value is calculated using the turbine power, the gas temperature upstream of the turbine and the exhaust flow rate.

According to a method for determining a basic boost pressure of an engine provided by the present invention, when the actuator at the turbine end is in a maximum opening state, based on adiabatic expansion inside the turbine and the first law of thermodynamics, the first exhaust back pressure value is calculated using turbine power, gas temperature upstream of the turbine, and exhaust flow rate, including:

Based on turbine power P _trb , turbine upstream gas temperature T ₃ and exhaust flow The first exhaust back pressure value p _3,trb is calculated as follows:

Where η _trb is the turbine efficiency, cp _,exh is the exhaust specific heat capacity, p ₄ is the pressure downstream of the turbine, κ _exh is the exhaust ideal gas adiabatic index, and _Δptrb is the pressure drop generated when the gas passes through the turbine.

According to a method for determining a basic boost pressure of an engine provided by the present invention, the system state quantity includes a flow rate through a compressor, an intake air temperature, a gas temperature upstream of a turbine, an engine speed, an intake VVT, and an exhaust VVT;

Accordingly, according to the basic boost pressure initial value and the system state quantity, the second exhaust back pressure value is calculated using a pre-built engine charging model, including:

Acquiring the engine intake flow rate according to the flow rate passing through the compressor;

Calculating the engine charging efficiency according to the engine intake flow rate and the engine speed;

A charging slope is calculated according to the intake VVT and the intake temperature;

Based on the ideal gas equation, the second exhaust back pressure value is calculated using the engine charging efficiency, intake VVT, exhaust VVT, the basic boost pressure initial value and the charging slope.

According to a method for determining a basic boost pressure of an engine provided by the present invention, the second exhaust back pressure value is calculated based on the ideal gas equation using the engine charging efficiency, intake VVT, exhaust VVT, the initial value of the basic boost pressure and the charging slope, including:

The second exhaust back pressure value p _3,chrg is calculated according to the engine charging efficiency rl, the intake VVT, the exhaust VVT, the initial value of the boost pressure p _21,basc and the charging slope fac _chrg :

rl＝fac _chrg .(p _21,basc -p _res );

Where _T3 is the exhaust temperature, _rfres is the relative charge of residual exhaust gas in the cylinder, and _Tres is the target residual exhaust gas temperature in the cylinder.

According to a method for determining a basic boost pressure of an engine provided by the present invention, after performing iterative calculation based on the first exhaust back pressure value and the second exhaust back pressure value using a predefined iterative algorithm and using the value obtained by the iterative calculation as a new basic boost pressure initial value, the method further includes:

Using the new basic boost pressure initial value and the corresponding system state quantity as training data;

A basic boost pressure prediction model is obtained by training based on the training data;

Inputting the initial value of the boost pressure and the system state quantity of the engine into the basic boost pressure prediction model to predict the boost pressure value;

Wherein, the basic boost pressure prediction model is obtained based on at least one of pulse spectrum calibration, machine learning or Gaussian model.

According to a method for determining a basic engine boost pressure provided by the present invention, the predefined iterative algorithm is a dichotomy method or a Newton method.

The present invention also provides an engine charging control method, comprising:

Acquiring a basic boost pressure value based on any of the above-mentioned methods for determining the basic boost pressure of the engine;

Comparing the basic boost pressure value with the target boost pressure, wherein the target boost pressure is determined according to the engine torque requirement;

When the target boost pressure is greater than the basic boost pressure value, performing charging control through a throttle valve to achieve the target boost pressure;

In a case where the target boost pressure is greater than the basic boost pressure value, charging is performed through boost pressure control to achieve the target boost pressure.

The present invention also provides a device for determining a basic boost pressure of an engine, comprising:

A data acquisition module, used to obtain the initial value of the basic boost pressure and the system state quantity of the engine;

An exhaust back pressure calculation module, configured to calculate a first exhaust back pressure value and a second exhaust back pressure value respectively using a pre-built turbocharger model and an engine charging model according to the basic boost pressure initial value and the system state quantity;

an exhaust back pressure determination module, configured to determine whether a difference between the first exhaust back pressure value and the second exhaust back pressure value exceeds a preset threshold;

The boost value determination module is used to determine a basic boost pressure value according to the first exhaust back pressure value and the second exhaust back pressure value when the difference between the first exhaust back pressure value and the second exhaust back pressure value does not exceed a preset threshold value, so as to achieve intake control.

The present invention also provides an engine charging control device, comprising:

A basic boost pressure determination module, used for obtaining a basic boost pressure value based on the above-mentioned engine basic boost pressure determination device;

A boost pressure comparison module, used to compare the basic boost pressure value with a target boost pressure; wherein the target boost pressure is determined according to the engine torque requirement;

a throttle control module, configured to perform charging control through a throttle valve to achieve the target boost pressure when the target boost pressure is less than the basic boost pressure value;

The boost control module is used to perform inflation through boost control to achieve the target boost pressure when the target boost pressure is greater than the basic boost pressure value.

The present invention also provides an electronic device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the program, any one of the above-mentioned methods for determining basic engine boost pressure or engine charging control methods is implemented.

The present invention also provides a non-transitory computer-readable storage medium having a computer program stored thereon. When the computer program is executed by a processor, any one of the above-mentioned methods for determining basic engine boost pressure or engine charging control methods is implemented.

The present invention provides a method for determining a basic engine boost pressure and a method for controlling an engine charging, wherein the method for determining a basic engine boost pressure calculates a corresponding first exhaust back pressure value and a second exhaust back pressure value by utilizing a pre-constructed turbocharger model and an engine charging model, and determines a basic boost pressure value according to the first exhaust back pressure value and the second exhaust back pressure value when the difference between the first exhaust back pressure value and the second exhaust back pressure value does not exceed a preset threshold value, thereby accurately calculating the throttle upstream pressure when the throttle is fully open and the turbocharger adjustment element is in the maximum opening position, and accurately defining the use boundaries of the throttle and the turbocharger, reducing unnecessary throttling effects, and effectively reducing additional energy losses.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

FIG1 is a schematic flow chart of a method for determining a basic boost pressure of an engine provided by an embodiment of the present invention;

FIG2 is a flow chart of an engine charging control method according to an embodiment of the present invention;

3 is a second flow chart of an engine charging control method provided by an embodiment of the present invention;

4 is a structural block diagram of a device for determining basic engine boost pressure provided by an embodiment of the present invention;

5 is a structural block diagram of an engine charging control device provided by an embodiment of the present invention;

FIG. 6 is a schematic diagram of the physical structure of an electronic device provided by an embodiment of the present invention.

DETAILED DESCRIPTION

In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the drawings of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

FIG. 1 is a flow chart of a method for determining a basic engine boost pressure according to an embodiment of the present invention. As shown in FIG. 1 , a method for determining a basic engine boost pressure comprises the following steps:

S101, obtaining an initial value of a basic boost pressure and a system state quantity of the engine.

The step of obtaining the initial value of the basic boost pressure and the system state of the engine includes:

An initial value of the basic boost pressure is determined according to the engine operating condition.

Specifically, since the ambient pressure is closely related to the basic boost pressure, the pressure upstream of the compressor can be regarded as approximately equal to the ambient pressure, and all the boost effects of the compressor are based on the ambient pressure. Therefore, the initial value of the initial boost pressure in this embodiment is the current ambient pressure of the engine.

It should be noted that, in addition to the ambient pressure, the main physical quantities that determine the initial value of the basic boost pressure also include the ambient temperature (which determines the intake air density) and the current intake air flow rate (ie, the gas flow rate passing through the compressor).

The system state quantities of the engine are obtained through multiple sensors or models.

Specifically, the system state quantity can be directly measured by different sensors or calculated by corresponding models.

The system state quantity X specifically includes the ambient pressure p ₀ , the current air-fuel ratio λ, the flow through the compressor, the compressor upstream gas temperature T ₁ , the intake temperature T ₂ , the turbine upstream gas temperature T ₃ , the engine speed n _Eng , the intake VVT (indicating the intake valve opening/closing time) and the exhaust VVT (indicating the exhaust valve opening/closing time).

Among them, some of the system state quantities X are obtained by monitoring corresponding sensors. For example, the ambient pressure is obtained by the ambient pressure sensor, the current air-fuel ratio is obtained by the oxygen sensor, the compressor flow is measured by the flow meter, and the intake VVT and exhaust VVT are obtained by the phase sensor.

Some system state quantities are calculated through corresponding physical models. For example, the gas temperature upstream of the compressor is modeled based on the ambient temperature sensor, and the gas temperature upstream of the turbine is modeled through the exhaust temperature model.

S102: According to the basic boost pressure initial value and the system state quantity, a corresponding first exhaust back pressure value and a corresponding second exhaust back pressure value are calculated using a pre-built turbocharger model and an engine charging model respectively.

The turbocharger model is constructed based on the relationship among turbocharger, basic boost pressure and exhaust back pressure, and the engine charging model is constructed based on the relationship among engine charging, basic boost pressure and exhaust back pressure.

In this step, the first exhaust back pressure value and the second exhaust back pressure value are compared in the iterative algorithm for calculating the current basic boost pressure value, and the calculated basic boost pressure is the system state quantity for determining the usage boundary of the supercharger and the throttle.

In addition, both the turbocharger model and the engine charging model are two physical models under the air system. When calculating the basic boost pressure, there are two major physical prerequisites: a. The throttle is fully open (so the pressure before and after the throttle is balanced, and the boost pressure is equal to the manifold pressure); b. The turbocharger actuator in the system is in the maximum opening state.

In the entire large air system, the exhaust back pressure plays a connecting role and is a system state quantity shared by the turbocharger model and the engine charging model. Mathematically, the entire large air system is an algebraic loop consisting of a nonlinear relationship including the basic boost pressure and the exhaust back pressure. It is impossible to directly obtain an analytical solution for the basic boost pressure required by the present invention. Therefore, it is necessary to obtain a numerical solution through iterative calculations at the beginning.

S103: Determine whether a difference between the first exhaust back pressure value and the second exhaust back pressure value exceeds a preset threshold.

S104: When the difference between the first exhaust back pressure value and the second exhaust back pressure value does not exceed a preset threshold, a basic boost pressure value is determined according to the first exhaust back pressure value and the second exhaust back pressure value to achieve intake control.

In this step, when the difference between the first exhaust back pressure value and the second exhaust back pressure value does not exceed the preset threshold value, it means that the iteration termination condition is met, and the first exhaust back pressure value is very close to the second exhaust back pressure value, and the first exhaust back pressure value or the second exhaust back pressure value can be directly selected, or the average value between the first exhaust back pressure value and the second exhaust back pressure value can be taken. In this embodiment, the average value between the first exhaust back pressure value and the second exhaust back pressure value is used as the basic boost pressure value.

In addition, when the difference between the first exhaust back pressure value and the second exhaust back pressure value does not exceed a preset threshold value, it indicates that the calculation accuracy of the numerical solution of the basic boost pressure calculated by the iterative algorithm reaches the requirement, and there is no need to perform iterative calculation again. At this time, the basic boost pressure value is determined according to the first exhaust back pressure value and the second exhaust back pressure value, and the boost control is performed using the determined basic boost pressure value, so that the intake time is not too early or too late, thereby avoiding the throttle and the supercharger working at the same time, causing unnecessary throttling effect and causing additional energy loss.

A method for determining a basic boost pressure of an engine provided in an embodiment of the present invention calculates a corresponding first exhaust back pressure value and a second exhaust back pressure value by utilizing a pre-constructed turbocharger model and an engine charging model, and determines a basic boost pressure value according to the first exhaust back pressure value and the second exhaust back pressure value when the difference between the first exhaust back pressure value and the second exhaust back pressure value does not exceed a preset threshold value, thereby accurately calculating the throttle upstream pressure when the throttle is fully open and the turbocharger adjustment element is in the maximum opening position, and accurately defining the use boundaries of the throttle and the turbocharger, reducing unnecessary throttling effects, and effectively reducing additional energy losses.

Further, after determining whether the difference between the first exhaust back pressure value and the second exhaust back pressure value exceeds a preset threshold, the method further includes:

When the difference between the first exhaust back pressure value and the second exhaust back pressure value exceeds a preset threshold, an iterative calculation is performed based on the first exhaust back pressure value and the second exhaust back pressure value using a predefined iterative algorithm, and the value obtained by the iterative calculation is used as a new basic boost pressure initial value.

Specifically, when the difference between the first exhaust back pressure value and the second exhaust back pressure value exceeds a preset threshold, it indicates that the numerical solution calculation accuracy of the basic boost pressure calculated does not meet the requirement. The threshold is generally determined based on experience, and the required input in the iterative calculation process is the input of the turbocharger model and the charging model.

Among them, the predefined iterative algorithm is the bisection method or the Newton method.

Correspondingly, the first exhaust back pressure value and the second exhaust back pressure value are calculated based on the basic boost pressure initial value and the system state quantity using a pre-built turbocharger model and an engine charging model, respectively, including:

The turbocharger model and the engine charging model respectively calculate the corresponding new first exhaust back pressure value and new second exhaust back pressure value based on the new basic boost pressure initial value and the system state quantity.

Specifically, after obtaining a new basic boost pressure initial value, a new round of calculation and comparison of the first exhaust back pressure value and the second exhaust back pressure value is performed using the turbocharger model and the engine charging model, and finally a judgment is made as to whether the difference between the first exhaust back pressure value and the second exhaust back pressure value exceeds a preset threshold value. When the difference does not exceed the preset threshold value, the iterative update of the basic boost pressure initial value is stopped, and the final first exhaust back pressure value and the second exhaust back pressure value are output, and the basic boost pressure value is calculated based on the final first exhaust back pressure value and the second exhaust back pressure value.

Furthermore, the system state quantities include ambient pressure, current air-fuel ratio, flow through the compressor, gas temperature upstream of the compressor, and gas temperature upstream of the turbine.

Accordingly, according to the basic initial value of the boost pressure and the system state quantity, the first exhaust back pressure value is calculated using a pre-built turbocharger model, including:

Considering that the pressure drop generated when the gas passes through the air filter is directly related to the gas flow through the air filter, the pressure _drop generated when the gas passes through the air filter can be directly related to the gas flow through the air filter. Get the compressor upstream pressure p ₁ :

Where Δp _airflt is the pressure drop generated when the gas passes through the air filter.

The same calculation principle as above for the compressor upstream pressure _p1 , according to the compressor flow The compressor downstream pressure p ₂₀ is obtained from the basic boost pressure initial value p _21,basc :

Where _Δpico is the pressure drop generated when the gas passes through the intake intercooler.

Based on the centrifugal compression process balance equation, the compressor power P _cmpr is obtained using the compressor upstream gas temperature T ₁ , the compressor upstream pressure p and the compressor downstream pressure p ₂₀ :

Where η _cmpr is the compressor efficiency, _cp,cmpr is the inlet specific heat, and K is the inlet ideal gas adiabatic index.

It should be noted that the calculation of the compressor power P _cmpr here is based on the balance equation of the centrifugal compression process, and the compressor compression is regarded as adiabatic compression in the calculation process.

Based on the energy and power balance principle, the compressor power P _cmpr is used to determine the turbine power P _trb :

_Ptrb ＝ _Pcmpr ；

It should be noted that the calculation of turbine power P _trb here is based on the turbine and compressor on the same shaft, and the turbine expansion and compressor compression processes satisfy the energy and power balance principle.

According to the flow rate through the compressor And the current air-fuel ratio λ to obtain the exhaust flow

Where k _air/fuel is the air-fuel coefficient.

When the actuator at the turbine end is at the maximum opening state, based on the adiabatic expansion inside the turbine and the first law of thermodynamics, the first exhaust back pressure value is calculated using the turbine power, the gas temperature upstream of the turbine, and the exhaust flow rate.

It should be noted that the equations between the above turbine power P _trb and the turbine efficiency η _trb etc. are obtained based on the adiabatic expansion inside the turbine and the first law of thermodynamics.

Specifically, the first exhaust back pressure value p _3,trb is calculated based on the turbine power P _trb , the turbine upstream gas temperature T ₃ and the exhaust flow rate:

Where η _trb is the turbine efficiency, cp _,exh is the exhaust specific heat capacity, p ₄ is the pressure downstream of the turbine, κ _exh is the exhaust ideal gas adiabatic index, and _Δptrb is the pressure drop generated when the gas passes through the turbine.

Furthermore, the system state quantities include flow through the compressor, intake temperature, gas temperature upstream of the turbine, engine speed, intake VVT, and exhaust VVT.

Accordingly, according to the basic boost pressure initial value and the system state quantity, the second exhaust back pressure value is calculated using a pre-built engine charging model, including:

According to the compressor flow Get engine intake flow

In this embodiment, based on a basic assumption that the engine system is in a stable state, the intake flow rates at various positions of the intake pipeline are equal, so the engine intake flow rate is equal to the gas flow rate passing through the compressor, so the gas flow rate passing through the compressor can be calculated. Directly obtain the engine intake flow

According to the engine intake flow The engine charging efficiency rl is calculated with the engine speed n _Eng :

In the formula, It is the conversion factor of speed-related charging efficiency and intake air flow.

The charging slope fac _chrg is calculated according to the intake VVT and the intake temperature _T2 :

Where, p _ref is the standard charging pressure, T _ref is the standard charging temperature, V _stroke,eff is the effective intake volume of the cylinder, and V _stroke is the geometric volume of the cylinder.

Based on the ideal gas equation, the second exhaust back pressure value p _3,chrg is calculated using the engine charging efficiency rl, intake VVT, exhaust VVT, the basic boost pressure initial value p _21,basc and the charging slope fac _chrg .

Specifically, the second exhaust back pressure value p _3,chrg is calculated according to the engine charging efficiency rl, the intake VVT, the exhaust VVT, the initial value of the boost pressure p _21,basc and the charging slope fac _chrg :

rl=fac _chrg· (p _{21, base} -p _res );

Where, T ₃ is the exhaust temperature, _rfres is the relative charge of residual exhaust gas in the cylinder, and _Tres is the target residual exhaust gas temperature in the cylinder. According to the definition of basic boost pressure, when the throttle is fully open, the manifold pressure is equal to the basic boost pressure.

In this embodiment, the second exhaust back pressure value p3 _,chrg is obtained by taking the gas in the cylinder as the research object based on the ideal gas equation, the initial value of the basic boost pressure, the residual exhaust gas partial pressure in the cylinder, the current charging slope and the physical relationship between the charging efficiency.

Further, after performing iterative calculation based on the first exhaust back pressure value and the second exhaust back pressure value using a predefined iterative algorithm and using the value obtained by the iterative calculation as a new basic boost pressure initial value, the method further includes:

The new basic boost pressure initial value and the corresponding system state quantity are used as training data.

A basic boost pressure prediction model is obtained by training based on the training data.

The initial value of the boost pressure and the system state quantity of the engine are input into the basic boost pressure prediction model to predict the boost pressure value.

Wherein, the basic boost pressure prediction model is obtained based on at least one of pulse spectrum calibration, machine learning or Gaussian model.

Specifically, when the difference between the first exhaust back pressure value and the second exhaust back pressure value exceeds a preset threshold, an iterative calculation is performed based on the first exhaust back pressure value and the second exhaust back pressure value using a predefined iterative algorithm. The above iterative calculation process needs to be performed online in the controller, but due to the limitation of the controller computing power, the number of iterations may be limited, resulting in insufficient accuracy of the calculation result.

In order to solve the above problems, the present invention changes the input physical values of the turbocharger model and the engine charging model (i.e., the system state quantities) within a reasonable range, and performs offline calculations on the above iterative process, thereby generating a data set consisting of the basic boost pressure initial value and the corresponding system state quantities.

Furthermore, the above data set is used as learning data for training a data-based model to obtain a trained data model (i.e., a basic boost pressure prediction model). The trained data model can be directly applied to the controller for real-time calculations, thereby reducing computing power requirements.

The data-based model may be a traditional calibration map, or other data-based models such as a Neutral network, a Gaussian model, etc.

It should be noted that the method for determining the basic engine boost pressure of the present invention can be applied to engines with a combination of Miller cycle and VGT supercharging system, and can also be applied to other high-efficiency turbocharging systems and different engine working cycles (for example: Otto, Attkinson).

FIG. 2 is a flow chart of the engine charging control method provided in an embodiment of the present invention; FIG. 3 is a second flow chart of the engine charging control method provided in an embodiment of the present invention.

As shown in FIGS. 2 and 3 , an engine charging control method includes the following steps:

S201, obtaining a basic boost pressure value based on the above-mentioned method for determining the basic boost pressure of the engine.

S202: Compare the basic boost pressure value with the target boost pressure.

The target boost pressure is determined according to the engine torque requirement.

S203, when the target boost pressure is less than the basic boost pressure value, performing charging control through a throttle valve to achieve the target boost pressure.

S204, when the target boost pressure is greater than the basic boost pressure value, performing inflation through boost control to achieve the target boost pressure.

Specifically, if the basic boost pressure is greater than the target boost pressure corresponding to the required torque, there is no need for boost control intervention, and the throttle control is used to adjust the engine intake volume to achieve the target boost pressure; otherwise, it is necessary to turn on the boost control and close the opening of the E-Wastegate or VGT.

In boost control, accurate calculation of basic boost pressure plays a very important role; if the basic boost pressure calculation is inaccurate, it will lead to errors in the timing of boost control intervention; intervening too early will increase pumping losses and affect fuel consumption; intervening too late will cause uneven torque output and affect drivability.

An engine charging control method provided by an embodiment of the present invention determines a specific charging control mode by comparing the basic boost pressure value with the target boost pressure based on accurate calculation of the basic boost pressure, thereby ensuring the accuracy of the charging control, reducing fuel consumption and improving driving performance.

The following is a description of the basic engine boost pressure determination device provided by the present invention. The basic engine boost pressure determination device described below and the basic engine boost pressure determination method described above can refer to each other.

FIG4 is a structural block diagram of a device for determining a basic engine boost pressure according to an embodiment of the present invention. As shown in FIG4 , a device for determining a basic engine boost pressure includes:

The data acquisition module 401 is used to acquire the initial value of the basic boost pressure and the system state quantity of the engine.

The step of obtaining the initial value of the basic boost pressure and the system state of the engine includes:

An initial value of the basic boost pressure is determined according to the engine operating condition.

Specifically, since the ambient pressure is closely related to the basic boost pressure, the pressure upstream of the compressor can be regarded as approximately equal to the ambient pressure, and all boost effects of the compressor are based on the ambient pressure. Therefore, the initial value of the initial boost pressure in this embodiment is the current ambient pressure of the engine.

It should be noted that, in addition to the ambient pressure, the main physical quantities that determine the initial value of the basic boost pressure also include the ambient temperature (which determines the intake air density) and the current intake air flow rate (ie, the gas flow rate passing through the compressor).

The system state quantities of the engine are obtained through multiple sensors or models.

Specifically, the system state quantity can be directly measured by different sensors or calculated by corresponding models.

The system state quantity X specifically includes the ambient pressure p ₀ , the current air-fuel ratio λ, the flow through the compressor, the compressor upstream gas temperature T ₁ , the intake air temperature T ₂ , the turbine upstream gas temperature T ₃ , the engine speed n _Eng , the intake VVT (indicating the intake valve opening/closing time) and the exhaust VVT (indicating the exhaust valve opening/closing time).

Among them, some of the system state quantities X are obtained by monitoring corresponding sensors. For example, the ambient pressure is obtained by the ambient pressure sensor, the current air-fuel ratio is obtained by the oxygen sensor, the compressor flow is measured by the flow meter, and the intake VVT and exhaust VVT are obtained by the phase sensor.

Some system state quantities are calculated through corresponding physical models. For example, the gas temperature upstream of the compressor is modeled based on the ambient temperature sensor, and the gas temperature upstream of the turbine is modeled through the exhaust temperature model.

The exhaust back pressure calculation module 402 is used to calculate the corresponding first exhaust back pressure value and second exhaust back pressure value according to the basic boost pressure initial value and the system state quantity using a pre-built turbocharger model and an engine charging model.

The turbocharger model is constructed based on the relationship among turbocharger, basic boost pressure and exhaust back pressure, and the engine charging model is constructed based on the relationship among engine charging, basic boost pressure and exhaust back pressure.

In this module, the first exhaust back pressure value and the second exhaust back pressure value are compared in the iterative algorithm for calculating the current basic boost pressure value. The calculated basic boost pressure is the system state quantity for judging the usage boundary of the supercharger and the throttle.

In addition, both the turbocharger model and the engine charging model are two physical models under the air system. When calculating the basic boost pressure, there are two major physical prerequisites: a. The throttle is fully open (so the pressure before and after the throttle is balanced, and the boost pressure is equal to the manifold pressure); b. The turbocharger actuator in the system is in the maximum opening state.

In the entire large air system, the exhaust back pressure plays a connecting role and is a system state quantity shared by the turbocharger model and the engine charging model. Mathematically, the entire large air system is an algebraic loop consisting of a nonlinear relationship including the basic boost pressure and the exhaust back pressure. It is impossible to directly obtain an analytical solution for the basic boost pressure required by the present invention. Therefore, it is necessary to obtain a numerical solution through iterative calculations at the beginning.

The exhaust back pressure determination module 403 is used to determine whether the difference between the first exhaust back pressure value and the second exhaust back pressure value exceeds a preset threshold.

The boost value determination module 404 is used to determine a basic boost pressure value according to the first exhaust back pressure value and the second exhaust back pressure value when the difference between the first exhaust back pressure value and the second exhaust back pressure value does not exceed a preset threshold value, so as to achieve intake control.

In this module, when the difference between the first exhaust back pressure value and the second exhaust back pressure value does not exceed the preset threshold value, it means that the iteration termination condition is met, and the first exhaust back pressure value is very close to the second exhaust back pressure value, and the first exhaust back pressure value or the second exhaust back pressure value can be directly selected, or the average value between the first exhaust back pressure value and the second exhaust back pressure value can be taken. In this embodiment, the average value between the first exhaust back pressure value and the second exhaust back pressure value is used as the basic boost pressure value.

In addition, when the difference between the first exhaust back pressure value and the second exhaust back pressure value does not exceed a preset threshold value, it indicates that the calculation accuracy of the numerical solution of the basic boost pressure calculated by the iterative algorithm reaches the requirement, and there is no need to perform iterative calculation again. At this time, the basic boost pressure value is determined according to the first exhaust back pressure value and the second exhaust back pressure value, and the boost control is performed using the determined basic boost pressure value, so that the intake time is not too early or too late, thereby avoiding the throttle and the supercharger working at the same time, causing unnecessary throttling effect and causing additional energy loss.

The engine basic boost pressure determination device provided in an embodiment of the present invention calculates the corresponding first exhaust back pressure value and second exhaust back pressure value by utilizing a pre-constructed turbocharger model and an engine charging model, and determines the basic boost pressure value according to the first exhaust back pressure value and the second exhaust back pressure value when the difference between the first exhaust back pressure value and the second exhaust back pressure value does not exceed a preset threshold value, thereby accurately calculating the throttle upstream pressure when the throttle is fully opened and the turbocharger adjustment element is in the maximum opening position, and accurately defining the use boundaries of the throttle and the turbocharger, reducing unnecessary throttling effects, and effectively reducing additional energy losses.

The engine charging control device provided by the present invention is described below. The engine charging control device described below and the engine charging control method described above can be referred to each other.

Figure 5 is a structural block diagram of an engine charging control device provided in an embodiment of the present invention. As shown in Figure 5, an engine charging control device includes a basic boost pressure determination module 501, a boost pressure comparison module 502, a throttle control module 503 and a boost control module 504.

The basic boost pressure determination module 501 is used to obtain a basic boost pressure value based on the above-mentioned engine basic boost pressure determination device.

The boost pressure comparison module 502 is used to compare the basic boost pressure value with the target boost pressure.

The target boost pressure is determined according to the engine torque requirement.

The throttle control module 503 is used to perform charging control through the throttle to achieve the target boost pressure when the target boost pressure is less than the basic boost pressure value.

The boost control module 504 is configured to, when the target boost pressure is greater than the basic boost pressure value, perform inflation through boost control to achieve the target boost pressure.

Specifically, if the basic boost pressure is greater than the target boost pressure corresponding to the required torque, there is no need for boost control intervention, and the throttle control is used to adjust the engine intake volume to achieve the target boost pressure; otherwise, it is necessary to turn on the boost control and close the opening of the E-Wastegate or VGT.

In boost control, accurate calculation of basic boost pressure plays a very important role; if the basic boost pressure calculation is inaccurate, it will lead to errors in the timing of boost control intervention; intervening too early will increase pumping losses and affect fuel consumption; intervening too late will cause uneven torque output and affect drivability.

An engine charging control device provided in an embodiment of the present invention determines a specific charging control method by comparing the basic boost pressure value with the target boost pressure based on accurate calculation of the basic boost pressure, thereby ensuring the accuracy of the charging control, reducing fuel consumption and improving driving performance.

Figure 6 is a schematic diagram of the physical structure of an electronic device provided by an embodiment of the present invention. As shown in Figure 6, the electronic device may include: a processor (processor) 610, a communication interface (Communications Interface) 620, a memory (memory) 630 and a communication bus 640, wherein the processor 610, the communication interface 620, and the memory 630 communicate with each other through the communication bus 640. The processor 610 can call the logic instructions in the memory 630 to execute the method for determining the basic boost pressure of the engine, and the method for determining the basic boost pressure of the engine includes: obtaining the initial value of the basic boost pressure and the system state of the engine; according to the initial value of the basic boost pressure and the system state, respectively using the pre-built turbocharger model and the engine charging model to calculate the corresponding first exhaust back pressure value and second exhaust back pressure value; judging whether the difference between the first exhaust back pressure value and the second exhaust back pressure value exceeds a preset threshold value; when the difference between the first exhaust back pressure value and the second exhaust back pressure value does not exceed the preset threshold value, determining the basic boost pressure value according to the first exhaust back pressure value and the second exhaust back pressure value to achieve intake control.

To execute an engine charging control method, the engine charging control method includes: obtaining a basic boost pressure value based on the above-mentioned engine basic boost pressure determination method; comparing the basic boost pressure value with a target boost pressure; wherein the target boost pressure is determined according to the engine torque demand; when the target boost pressure is less than the basic boost pressure value, performing charging control through a throttle valve to achieve the target boost pressure; when the target boost pressure is greater than the basic boost pressure value, performing charging through boost control to achieve the target boost pressure.

In addition, the logic instructions in the above-mentioned memory 630 can be implemented in the form of a software functional unit and can be stored in a computer-readable storage medium when it is sold or used as an independent product. Based on such an understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art or the part of the technical solution, can be embodied in the form of a software product, and the computer software product is stored in a storage medium, including a number of instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the methods of each embodiment of the present invention. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), disk or optical disk and other media that can store program codes.

On the other hand, the present invention also provides a non-transitory computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, is implemented to execute the engine basic boost pressure determination method provided by the above method, the engine basic boost pressure determination method comprising: obtaining a basic boost pressure initial value and a system state quantity of the engine; according to the basic boost pressure initial value and the system state quantity, respectively calculating a corresponding first exhaust back pressure value and a second exhaust back pressure value using a pre-built turbocharger model and an engine charging model; determining whether the difference between the first exhaust back pressure value and the second exhaust back pressure value exceeds a preset threshold value; when the difference between the first exhaust back pressure value and the second exhaust back pressure value does not exceed the preset threshold value, determining a basic boost pressure value according to the first exhaust back pressure value and the second exhaust back pressure value to achieve intake control.

To execute an engine charging control method, the engine charging control method includes: obtaining a basic boost pressure value based on the above-mentioned engine basic boost pressure determination method; comparing the basic boost pressure value with a target boost pressure; wherein the target boost pressure is determined according to the engine torque demand; when the target boost pressure is less than the basic boost pressure value, performing charging control through a throttle valve to achieve the target boost pressure; when the target boost pressure is greater than the basic boost pressure value, performing charging through boost control to achieve the target boost pressure.

The device embodiments described above are merely illustrative, wherein the units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, i.e., they may be located in one place, or they may be distributed on multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the scheme of this embodiment. Those of ordinary skill in the art may understand and implement it without creative effort.

Through the description of the above implementation methods, those skilled in the art can clearly understand that each implementation method can be implemented by means of software plus a necessary general hardware platform, and of course, it can also be implemented by hardware. Based on this understanding, the above technical solution is essentially or the part that contributes to the prior art can be embodied in the form of a software product, and the computer software product can be stored in a computer-readable storage medium, such as ROM/RAM, a disk, an optical disk, etc., including a number of instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to execute the methods of each embodiment or some parts of the embodiment.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims (12)

1. A method for determining a basic boost pressure of an engine, comprising: Obtaining the initial value of basic boost pressure and the system state quantity of the engine; According to the basic boost pressure initial value and the system state quantity, a corresponding first exhaust back pressure value and a corresponding second exhaust back pressure value are calculated using a pre-built turbocharger model and an engine charging model respectively; determining whether a difference between the first exhaust back pressure value and the second exhaust back pressure value exceeds a preset threshold; When the difference between the first exhaust back pressure value and the second exhaust back pressure value does not exceed a preset threshold, a basic boost pressure value is determined according to the first exhaust back pressure value and the second exhaust back pressure value to achieve intake control; When the difference between the first exhaust back pressure value and the second exhaust back pressure value exceeds a preset threshold value, an iterative calculation is performed based on the first exhaust back pressure value and the second exhaust back pressure value using a predefined iterative algorithm, and the value obtained by the iterative calculation is used as a new basic boost pressure initial value; accordingly, the turbocharger model and the engine charging model respectively calculate the corresponding new first exhaust back pressure value and new second exhaust back pressure value based on the new basic boost pressure initial value and the system state quantity. 2. The method for determining the basic boost pressure of an engine according to claim 1, characterized in that the system state quantity includes ambient pressure, current air-fuel ratio, flow through the compressor, gas temperature upstream of the compressor, and gas temperature upstream of the turbine; Accordingly, according to the basic initial value of the boost pressure and the system state quantity, the first exhaust back pressure value is calculated using a pre-built turbocharger model, including: Obtaining the compressor upstream pressure according to the ambient pressure and the flow rate passing through the compressor; Acquire the pressure downstream of the compressor according to the flow rate through the compressor and the initial value of the basic boost pressure; Based on the centrifugal compression process balance equation, the compressor power is obtained using the compressor upstream gas temperature, the compressor upstream pressure and the compressor downstream pressure; Based on the energy and power balance principle, the turbine power is determined using the compressor power; Obtain the exhaust flow rate according to the flow rate through the compressor and the current air-fuel ratio; When the turbine-end actuator is at the maximum opening state, the first exhaust back pressure value is calculated based on the adiabatic expansion inside the turbine and the first law of thermodynamics using the turbine power, the gas temperature upstream of the turbine, and the exhaust flow rate. 3. The method for determining the basic boost pressure of an engine according to claim 2, characterized in that, when the turbine end actuator is in the maximum opening state, based on the adiabatic expansion inside the turbine and the first law of thermodynamics, the first exhaust back pressure value is calculated using the turbine power, the gas temperature upstream of the turbine and the exhaust flow rate, comprising: Based on turbine power P _trb , turbine upstream gas temperature T ₃ and exhaust flow The first exhaust back pressure value p _3,trb is calculated as follows: Where η _trb is the turbine efficiency, cp _,exh is the exhaust specific heat capacity, p ₄ is the pressure downstream of the turbine, κ _exh is the exhaust ideal gas adiabatic index, and _Δptrb is the pressure drop generated when the gas passes through the turbine. 4. The method for determining the basic boost pressure of an engine according to claim 1, characterized in that the system state quantity includes the flow through the compressor, the intake temperature, the gas temperature upstream of the turbine, the engine speed, the intake VVT, and the exhaust VVT; Accordingly, according to the basic boost pressure initial value and the system state quantity, the second exhaust back pressure value is calculated using a pre-built engine charging model, including: Acquiring the engine intake flow rate according to the flow rate passing through the compressor; Calculating the engine charging efficiency according to the engine intake flow rate and the engine speed; A charging slope is calculated according to the intake VVT and the intake temperature; Based on the ideal gas equation, the second exhaust back pressure value is calculated using the engine charging efficiency, intake VVT, exhaust VVT, the basic boost pressure initial value and the charging slope. 5. The method for determining the basic boost pressure of an engine according to claim 4, characterized in that the second exhaust back pressure value is calculated based on the ideal gas equation using the engine charging efficiency, intake VVT, exhaust VVT, the initial value of the basic boost pressure and the charging slope, comprising: The second exhaust back pressure value p _3,chrg is calculated according to the engine charging efficiency rl, the intake VVT, the exhaust VVT, the initial value of the boost pressure p _21,basc and the charging slope fac _chrg : rl＝fac _chrg .(p _21,basc -p _res ); Where _T2 is the intake temperature, _T3 is the exhaust temperature, _rfres is the relative charge of residual exhaust gas in the cylinder, and _Tres is the target residual exhaust gas temperature in the cylinder. 6. The method for determining the basic boost pressure of an engine according to claim 1, characterized in that after performing iterative calculation based on the first exhaust back pressure value and the second exhaust back pressure value using a predefined iterative algorithm and using the value obtained by the iterative calculation as a new basic boost pressure initial value, the method further comprises: Using the new basic boost pressure initial value and the corresponding system state quantity as training data; A basic boost pressure prediction model is obtained by training based on the training data; Inputting the initial value of the boost pressure and the system state of the engine into the basic boost pressure prediction model to predict the boost pressure value; Wherein, the basic boost pressure prediction model is obtained based on at least one of pulse spectrum calibration, machine learning or Gaussian model. 7 . The method for determining a basic engine boost pressure according to claim 1 , wherein the predefined iterative algorithm is a binary method or a Newton method. 8. An engine charging control method, characterized by comprising: Obtaining a basic boost pressure value based on the method for determining a basic engine boost pressure according to any one of claims 1 to 7; Comparing the basic boost pressure value with the target boost pressure, wherein the target boost pressure is determined according to the engine torque requirement; When the target boost pressure is greater than the basic boost pressure value, performing charging control through a throttle valve to achieve the target boost pressure; In a case where the target boost pressure is not greater than the basic boost pressure value, charging is performed through boost pressure control to achieve the target boost pressure. 9. A device for determining basic engine boost pressure, comprising: A data acquisition module, used to obtain the initial value of the basic boost pressure and the system state quantity of the engine; An exhaust back pressure calculation module, configured to calculate a first exhaust back pressure value and a second exhaust back pressure value respectively using a pre-built turbocharger model and an engine charging model according to the basic boost pressure initial value and the system state quantity; an exhaust back pressure determination module, configured to determine whether a difference between the first exhaust back pressure value and the second exhaust back pressure value exceeds a preset threshold; A boost value determination module is used to determine a basic boost pressure value according to the first exhaust back pressure value and the second exhaust back pressure value when the difference between the first exhaust back pressure value and the second exhaust back pressure value does not exceed a preset threshold value, so as to realize intake control; when the difference between the first exhaust back pressure value and the second exhaust back pressure value exceeds a preset threshold value, based on the first exhaust back pressure value and the second exhaust back pressure value, an iterative calculation is performed using a predefined iterative algorithm, and the value obtained by the iterative calculation is used as a new basic boost pressure initial value, and accordingly, the turbocharger model and the engine charging model respectively calculate the corresponding new first exhaust back pressure value and new second exhaust back pressure value based on the new basic boost pressure initial value and the system state quantity. 10. An engine charging control device, comprising: a basic boost pressure determination module, configured to obtain a basic boost pressure value based on the engine basic boost pressure determination device according to claim 9; A boost pressure comparison module, used to compare the basic boost pressure value with a target boost pressure; wherein the target boost pressure is determined according to the engine torque requirement; a throttle control module, configured to perform charging control through a throttle valve to achieve the target boost pressure when the target boost pressure is less than the basic boost pressure value; The boost control module is used to perform inflation through boost control to achieve the target boost pressure when the target boost pressure is greater than the basic boost pressure value. 11. An electronic device comprising a memory, a processor and a computer program stored in the memory and executable on the processor, wherein when the processor executes the program, the method for determining the basic engine boost pressure as described in any one of claims 1 to 7 or the method for controlling the engine charging as described in claim 8 is implemented. 12. A non-transitory computer-readable storage medium having a computer program stored thereon, wherein when the computer program is executed by a processor, the method for determining a basic engine boost pressure as described in any one of claims 1 to 7 or the method for controlling an engine charge as described in claim 8 is implemented.