KR102024536B1 - Simulation method and device for disel engine - Google Patents

Abstract

Disclosed are a diesel engine simulation method and apparatus that can more quickly and accurately characterize a diesel engine. The disclosed diesel engine simulation method uses the exhaust gas pressure value and temperature value of the diesel engine, the EGR valve opening area value of the EGR device, and the pressure value of the exhaust gas of the EGR device to control the circulation gas circulated by the EGR device. Calculating an air flow rate value; Generating a subtraction value by subtracting the first air flow rate value from the second air flow rate value for the diesel engine; And calculating nitrogen oxide emissions of the diesel engine by using the subtraction value and nitrogen oxide emissions according to the operating point of the diesel engine.

Description

Diesel engine simulation method and apparatus {SIMULATION METHOD AND DEVICE FOR DISEL ENGINE}

The present invention relates to a method and apparatus for simulating a diesel engine, and more particularly, to a method and apparatus for simulating a diesel engine capable of analyzing the characteristics of a diesel engine more quickly.

In the automotive industry, the use of diesel engines is increasing because of their high power, fuel economy and durability advantages over gasoline engines. However, more sophisticated engine control systems are needed to meet ever-increasing emissions regulations. Controlling Exhaust Gas Recirculation (EGR) and Variable Geometry Turbocharger (VGT) is one of the methods.

In order to control the engine, a simulation is performed using an air circulation model and an average engine model of a diesel engine. In the case of a diesel engine, the calculation is complicated and the simulation takes a long time to perform real-time control of the diesel engine. It is difficult. There is also a lack of research to analyze the characteristics of diesel engines considering the exhaust gas recirculation system and the supercharger.

As a related prior document, Korean Patent Publication No. 2018-0012534, a non-patent document, "Development of a method for correcting the supercharge pressure and EGR rate of a WGT diesel engine using an average value model, Jae-Woo Jung, Nam-Ho Kim, Chang-Hyun Kim, Deok-Jin Kim, Ki-Yong Kim, Korea Vol. 24, No. 3, May 2016, 319-329.

The present invention is to provide a diesel engine simulation method and apparatus that can more quickly and accurately characterize the diesel engine.

In addition, the present invention is to provide a diesel engine simulation method and apparatus that can support the power distribution control of the diesel engine in consideration of the emissions of nitrogen oxides.

According to an embodiment of the present invention for achieving the above object, by using the exhaust gas pressure value and temperature value of the diesel engine, the EGR valve opening area value of the EGR device, the pressure value of the exhaust gas of the EGR device, Calculating a first air flow rate value of the circulating gas circulated by the EGR device; Generating a subtraction value by subtracting the first air flow rate value from the second air flow rate value for the diesel engine; And calculating nitrogen oxide emissions of the diesel engine using the subtraction value and nitrogen oxide emissions according to the operating point of the diesel engine.

In addition, according to another embodiment of the present invention for achieving the above object, a data receiving unit for receiving the required torque value of the driver and the rotational speed value of the diesel engine; The first air flow rate value circulated by the EGR device is calculated using the exhaust gas pressure value and the temperature value of the diesel engine, the EGR valve opening area value of the EGR device, and the pressure value of the exhaust gas of the EGR device. A data calculation unit for calculating nitrogen oxide emissions of the diesel engine by using an air flow rate value, a second air flow rate value for the diesel engine, and nitrogen oxide emissions according to an operating point of the diesel engine; And a characteristic value output unit configured to output the calculated nitrogen oxide emissions.

According to the present invention, it is possible to analyze the characteristics of the diesel engine more quickly and accurately, and the analysis result can be utilized for controlling the diesel engine.

In addition, according to the present invention, since the emission of nitrogen oxides in consideration of the EGR device and the supercharger can be calculated, the power distribution of the diesel engine can be controlled to minimize the emission of nitrogen oxides through the simulation according to the present invention.

1 is a view for explaining a diesel engine model used in the present invention.
2 is a view showing a specific diesel engine model for explaining a simulation method according to an embodiment of the present invention.
3 is a flowchart of a diesel engine simulation method according to an embodiment of the present invention.
4 is a view for explaining a diesel engine simulation apparatus according to an embodiment of the present invention.
5 is a view showing the opening area map data of the EGR valve according to an embodiment of the present invention.

As the invention allows for various changes and numerous embodiments, particular embodiments will be illustrated in the drawings and described in detail in the written description. However, this is not intended to limit the present invention to specific embodiments, it should be understood to include all modifications, equivalents, and substitutes included in the spirit and scope of the present invention. In describing the drawings, similar reference numerals are used for similar elements.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a view for explaining a diesel engine model used in the present invention.

1, a diesel engine model according to the present invention includes a cylinder 110, a fuel system 120, an intake manifold 130, an exhaust manifold 140, an EGR device 150, a supercharger 160, and an intercooler. And 170. According to an embodiment, the supercharger 160 may include an intercooler 170 and may be a turbocharger such as an available geometry turbocharger (VGT) or a waste gate turbocharger (WRT).

The fuel supplied by the fuel system 120 and the air supplied through the intake manifold 130 are supplied to the engine cylinder 110, and combustion of the fuel occurs in the cylinder 110. After combustion, the exhaust gas is delivered to the EGR device 150 and the supercharger 160 via an exhaust manifold 140. The EGR device 150 regulates the amount of exhaust gas circulated to the intake manifold 130 by adjusting the EGR valve, and the supercharger 160 uses the turbine that rotates by the pressure of the exhaust gas to take in the outside air. Transfer to fold 130. At this time, the supercharger 160 compresses the outside air using a compressor, and the temperature of the air increased by the compression is cooled by the intercooler 170.

The simulation method according to the present invention analyzes the effective torque, fuel mass flow rate and nitrogen oxide emissions of the diesel engine based on the required torque and the current engine speed of the driver inputted into the diesel engine model. The simulation method according to the present invention analyzes the characteristics of the diesel engine using test data for the actual diesel engine in addition to the required torque and the current engine speed. Such test data may include transient as well as steady state data.

The simulation method according to the present invention may be performed in a computing device including a processor. Hereinafter, a simulation method performed in a simulation device which is one of such computing devices will be described as an embodiment.

2 is a view showing a specific diesel engine model for explaining a simulation method according to an embodiment of the present invention.

The diesel engine model according to the present invention is a simplified model than the conventional diesel engine 1D model. When the simulation is performed using the diesel engine model according to the present invention, the calculation time required for the simulation may be further reduced. In addition, the diesel engine model according to the present invention may be used as a mean value model, as well as transient data as well as steady state data.

Hereinafter, the diesel engine model will be described in detail by dividing it into detailed models. Engine torque and fuel system models, supercharger models, intake manifold models, EGR and exhaust models are described in this order.

Engine Torque and Fuel System Model

)은 연료 밀도(

), 연료 분사량(

) 및 디젤 엔진의 엔진 속도(

)에 의해 결정되며, 연료 분사량은 요구 토크(

)에 따라 결정된다.The simulation apparatus according to the present invention calculates the fuel flow rate of the diesel engine and the effective torque of the diesel engine according to the required torque of the driver and the engine speed of the diesel engine. Fuel flow rate of diesel engine (

) Is the fuel density (

), Fuel injection volume (

) And engine speed of the diesel engine (

) Is determined by the required torque (

Is determined by).

As an example, the simulation apparatus may calculate the fuel flow rate of the diesel engine using Equation 1. Here, the fuel injection amount can be obtained from the test data on the fuel injection amount of the diesel engine according to the required torque.

And the simulation apparatus can calculate the effective torque of a diesel engine from the air fuel ratio of a diesel engine.

)의 비율로 계산되며, 공기 유량율은 이상 기체 방정식에 기반하여, 디젤 엔진의 엔진 속도, 체적 효율(

, volumetric efficiency) 및 부피(

)와, 흡기 매니폴드 압력(

) 및 온도(

)에 따라 계산될 수 있다. The air-fuel ratio λ is the fuel flow rate and the air flow rate of the diesel engine as shown in [Equation 2].

Air flow rate, based on the ideal gas equation, the engine speed, volumetric efficiency (

, volumetric efficiency) and volume (

) And intake manifold pressure (

) And temperature (

Can be calculated according to

Where R represents an ideal gas constant.

The volumetric efficiency of the diesel engine is determined by the engine speed of the diesel engine and the pressure of the intake manifold, and can be obtained from the volumetric efficiency test data of the diesel engine according to the engine speed and the pressure of the intake manifold.

)로부터 도시평균유효압력(IMEP, Indicated Mean Effective Pressure)를 계산하고, 평균유효압력으로부터 디젤 엔진의 유효 토크를 계산한다. 도시평균유효압력은 지시 열효율과 디젤 엔진의 연료 유량(

, fuelmass flow)으로부터 계산될 수 있으며, 지시 열효율은 공연비에 따라 결정된다.The simulation device is designed for the dedicated thermal efficiency of diesel engines.

Calculate the average mean effective pressure (IMEP) and calculate the effective torque of the diesel engine from the average effective pressure. The average city effective pressure is the indicated thermal efficiency and the fuel flow rate of the diesel engine.

This can be calculated from the fuel mass flow, and the indicated thermal efficiency depends on the air-fuel ratio.

)를 계산할 수 있다. 여기서,

는 연료의 저위발열량(lower heating value)을 나타낸다.In one embodiment, the simulation apparatus uses Equation 3 to calculate an effective torque of a diesel engine.

) Can be calculated. here,

Represents the lower heating value of the fuel.

)를 계산할 수 있다.Alternatively, the simulation apparatus according to another embodiment, using the equation (4) the effective torque of the diesel engine (

) Can be calculated.

Here, BMEP denotes a brake mean effective pressure, FMEP denotes a friction mean effective pressure, and PMEP denotes a pumping mean effective pressure.

That is, the simulation apparatus according to the present invention subtracts the loss due to friction (FMEP) or the pumping of the cylinder (PEMP) from the city average effective pressure instead of the city average effective pressure, and transmits it to the power shaft by using the BMEP. The torque to be calculated can be calculated as the effective torque.

< supercharger  Model>

)과 공기를 압축하는 컴프레셔의 압축비를 이용하여, 컴프레셔가 출력하는 압축 공기의 압력(

)을 계산한다. Simulation apparatus according to the present invention is the atmospheric pressure (

) And the pressure of the compressed air output by the compressor using the compression ratio of the compressor for compressing air.

Calculate

)는 디젤 엔진의 엔진 속도 및 연료 분사량에 의해 결정되며, 터빈 회전 속도에 따라 외부로부터 유입되는 공기 양이 달라지므로, 컴프레셔의 압축비(

)는 터빈 회전 속도 및 컴프레셔의 공기 유량율(

)에 따라 결정된다. Turbine rotational speed of the turbocharger supercharger, ie the rotational speed of the turbo shaft (

) Is determined by the engine speed and fuel injection amount of the diesel engine, and since the amount of air introduced from the outside depends on the turbine rotation speed, the compression ratio of the compressor (

) Is the turbine speed and the air flow rate of the compressor (

Is determined by).

As an example, the simulation apparatus may calculate the fuel flow rate of the diesel engine using Equation 5.

Here, the turbine rotation speed and the compression ratio of the compressor can be obtained from the test data for the diesel engine obtained by adjusting the parameters (engine speed, fuel injection amount, air flow rate of the compressor). And the air flow rate of the compressor can be obtained by analyzing the intake manifold model described later.

<Intake Manifold  Model>

The simulation apparatus according to the present invention calculates the air flow rate of the compressor using the air flow rate of the intake manifold, the air flow rate of the diesel engine, and the air flow rate of the circulating gas circulated by the EGR device.

)과 컴프레셔의 공기 유량율의 합은, 흡기 매니폴드 공기 유량율(

)과 디젤 엔진 공기 유량율의 합과 동일하다고 볼 수 있다.Since the circulating gas and the compressor air flow into the intake manifold and the diesel engine, the air flow rate of the circulating gas (

), The sum of the air flow rate of the compressor is the intake manifold air flow rate (

) And the diesel engine air flow rate.

Therefore, as an example, the simulation apparatus can calculate the air flow rate of the compressor as shown in [Equation 6]. And the air flow rate of the intake manifold can be calculated by the ideal gas equation.

은 흡기 매니폴드의 압력,

은 흡기 매니폴드의 부피,

는 흡기 매니폴드의 온도를 나타낸다. 흡기 매니폴드의 압력은 컴프레셔가 출력하는 압축 공기의 압력에 의해 결정될 수 있으며, 디젤엔진에 대한 시험 데이터로부터 얻어질 수 있다. 그리고 순환 가스의 공기 유량율은 후술되는 EGR 및 배기 모델을 해석하여 얻어질 수 있다.here,

Is the pressure of the intake manifold,

Is the volume of the intake manifold,

Represents the temperature of the intake manifold. The pressure of the intake manifold can be determined by the pressure of the compressed air output by the compressor, and can be obtained from test data for the diesel engine. And the air flow rate of the circulating gas can be obtained by analyzing the EGR and the exhaust model described later.

<EGR and Exhaust Models>

or P_exh) 및 온도(

or T_exh), EGR 장치의 EGR 밸브 개구 면적(

), EGR 장치의 배출 가스, 즉 순환 가스의 압력(

)을 이용하여, EGR 장치에 의해 순환되는 순환 가스의 공기 유량율을 계산하여, 디젤 엔진의 질소 산화물 배출량을 계산한다. 실험적으로 순환 가스의 압력과 흡기 매니폴드의 압력은 큰 차이가 없으므로, 흡기 매니폴드 압력을 순환 가스의 압력으로 이용할 수 있다.Simulation apparatus according to the present invention is the exhaust gas pressure (

or P _exh ) and temperature (

or T _exh ), EGR valve opening area (

), The exhaust gas of the EGR unit, i.e. the pressure of the circulating gas (

), The air flow rate of the circulating gas circulated by the EGR device is calculated to calculate the nitrogen oxide emissions of the diesel engine. Experimentally, since the pressure of the circulating gas and the pressure of the intake manifold do not differ significantly, the intake manifold pressure can be used as the pressure of the circulating gas.

)에서 순환 가스의 공기 유량율을 차감하고, 차감값 및 디젤 엔진의 동작점에 따른 질소산화물 배출량(

)을 이용하여, 디젤 엔진의 질소 산화물 배출량 즉, 공기 유량율(

)을 계산한다. 여기서, 디젤 엔진의 동작점은 디젤 엔진의 엔진 속도 및 연료 분사량을 나타낸다.Since some of the exhaust gas of the diesel engine is circulated by the EGR unit, the simulation unit is designed to calculate the air flow rate

), And deduct the air flow rate of the circulating gas, and the nitrogen oxide emissions according to the deduction value and the operating point of the diesel engine (

), The nitrogen oxide emissions of the diesel engine, that is, the air flow rate (

Calculate Here, the operating point of the diesel engine represents the engine speed and the fuel injection amount of the diesel engine.

As an example, the simulation apparatus may calculate the air flow rate of the circulating gas using Equation 7 and calculate the nitrogen oxide emissions using Equation 8.

는 배기 가스의 압력과 순환 가스의 압력에 따라 특정 값을 출력하는 함수(flow function)로서, 배기 가스의 압력에 반비례하고 순환 가스의 압력에 비례하는 값을 출력할 수 있으며, 실시예에 따라서 다양하게 결정될 수 있는 함수이다. In Equation 7,

Is a flow function that outputs a specific value according to the pressure of the exhaust gas and the pressure of the circulating gas, and may output a value inversely proportional to the pressure of the exhaust gas and proportional to the pressure of the circulating gas. Is a function that can be determined.

The flow rate of the circulating gas varies according to the opening area of the EGR valve, and the opening area of the EGR valve may be determined according to the engine speed and the fuel injection amount. The opening area of the EGR valve according to the engine speed and fuel injection amount can also be obtained from the test data for the diesel engine.

According to the present invention, it is possible to analyze the characteristics of the diesel engine more quickly and accurately, and the analysis result can be utilized for controlling the diesel engine.

In addition, according to the present invention, since the emission of nitrogen oxides in consideration of the EGR device and the supercharger can be calculated, the power distribution of the diesel engine can be controlled to minimize the emission of nitrogen oxides through the simulation according to the present invention.

3 is a flowchart of a diesel engine simulation method according to an embodiment of the present invention.

The simulation apparatus according to the present invention uses the exhaust gas pressure value and temperature value of the diesel engine, the EGR valve opening area value of the EGR device, and the pressure value of the exhaust gas of the EGR device, and thus the first apparatus of the circulating gas circulated by the EGR device. The air flow rate value is calculated (S310). Here, the pressure value of the exhaust gas of the EGR device may be the pressure value of the intake manifold of the diesel engine, and the exhaust gas pressure value and the temperature value may be determined according to the operating point of the diesel engine.

The simulation apparatus generates a subtraction value by subtracting the first air flow rate value from the second air flow rate value for the diesel engine (S320), and using the depletion value and the nitrogen oxide emissions according to the operating point of the diesel engine, the diesel Calculate the nitrogen oxide emissions of the engine (S330).

According to an embodiment, the simulation method according to the present invention comprises the fourth air flow rate value for the compressor of the supercharger by subtracting the first air flow rate value from the sum of the third air flow rate value and the second air flow rate value for the intake manifold. Calculating the pressure value of the compressor and calculating the pressure value of the intake manifold using the pressure value of the compressor according to the step of calculating the pressure, the fourth air flow rate value and the turbine rotational speed of the supercharger. have.

According to an embodiment, the simulation method according to the present invention may further include calculating a fuel flow rate of the diesel engine and an effective torque of the diesel engine according to the required torque of the driver and the engine speed of the diesel engine. The method may further include calculating a second air flow rate value using the speed, the volume of the diesel engine, the pressure value of the intake manifold, and the temperature. The simulation apparatus may further use the volumetric efficiency of the diesel engine to calculate the second air flow rate value.

4 is a view for explaining a diesel engine simulation apparatus according to an embodiment of the present invention, Figure 5 is a view showing the opening area map data of the EGR valve according to an embodiment of the present invention.

Referring to FIG. 4, the diesel engine simulation apparatus according to the present invention includes a data receiver 410, a data calculator 420, and a characteristic value output unit 430.

The data receiving unit 410 receives, i.e., receives the required torque value of the driver and the rotation speed value of the diesel engine. The required torque value and the rotational speed value can be input by the user.

The data calculator 420 calculates a characteristic value of the diesel engine based on an input value of the data receiver and a diesel engine model. As an example, the effective torque value and fuel may be calculated based on the diesel engine model of FIG. 2. At least one of the flow rate value and the nitrogen oxide emission may be calculated.

In one embodiment, the data calculation unit 420 is circulated by the EGR device using the exhaust gas pressure value and temperature value of the diesel engine, the EGR valve opening area value of the EGR device, and the pressure value of the exhaust gas of the EGR device. Compute a first air flow rate value of the circulating gas, using the first air flow rate value, the second air flow rate value for the diesel engine, and the nitrogen oxide emissions according to the operating point of the diesel engine, the nitrogen oxide of the diesel engine Calculate the emissions. More specifically, the data operation unit 420 generates a subtraction value by subtracting the first air flow rate value from the second air flow rate value for the diesel engine, and using the depletion value and the nitrogen oxide emissions according to the operating point of the diesel engine. Calculate the NOx emissions of diesel engines.

The characteristic value output unit 430 outputs the nitrogen oxide emissions of the diesel engine calculated by the data calculating unit 420.

The data calculator 420 may calculate the effective torque value and the fuel flow rate value by processing the data as described in FIG. 2 as well as the nitrogen oxide discharge, and the characteristic value output unit 430 may calculate the effective torque value and the fuel flow rate value. It can be output with nitrogen oxide emissions.

Meanwhile, the simulation apparatus according to the present invention may further include a data storage unit 440 for storing test data for the diesel engine or map data obtained from such test data. The data storage unit 440 may store various map data obtained from test data for a diesel engine. As an example, as shown in FIG. Can be stored.

The data calculator 420 may calculate a characteristic value of the diesel engine using the map data stored in the data storage 440.

The technical contents described above may be embodied in the form of program instructions that may be executed by various computer means and may be recorded in a computer readable medium. The computer readable medium may include program instructions, data files, data structures, etc. alone or in combination. Program instructions recorded on the media may be those specially designed and constructed for the purposes of the embodiments, or they may be of the kind well-known and available to those having skill in the computer software arts. Examples of computer-readable recording media include magnetic media such as hard disks, floppy disks, and magnetic tape, optical media such as CD-ROMs, DVDs, and magnetic disks, such as floppy disks. Magneto-optical media, and hardware devices specifically configured to store and execute program instructions, such as ROM, RAM, flash memory, and the like. Examples of program instructions include not only machine code generated by a compiler, but also high-level language code that can be executed by a computer using an interpreter or the like. The hardware device may be configured to operate as one or more software modules to perform the operations of the embodiments, and vice versa.

In the present invention as described above has been described by the specific embodiments, such as specific components and limited embodiments and drawings, but this is provided to help a more general understanding of the present invention, the present invention is not limited to the above embodiments. For those skilled in the art, various modifications and variations are possible from these descriptions. Therefore, the spirit of the present invention should not be limited to the described embodiments, and all of the equivalents or equivalents of the claims as well as the claims to be described later belong to the scope of the present invention. .

Claims (7)

Using the exhaust gas pressure value and temperature value of the diesel engine, the EGR valve opening area value of the EGR device, and the pressure value of the intake manifold of the diesel engine, the first air flow rate value of the circulating gas circulated by the EGR device is used. Calculating;
The sum of the third air flow rate value for the intake manifold and the second air flow rate value for the diesel engine is subtracted from the first air flow rate value that is proportional to the pressure value of the intake manifold. Calculating an air flow rate value;
Calculating a pressure value of the compressor according to the fourth air flow rate value and the turbine rotational speed of the supercharger;
Calculating a pressure value of the intake manifold using the pressure value of the compressor;
Calculating the second air flow rate value using an engine speed of the diesel engine, a volume of the diesel engine, a pressure value of the intake manifold, and a temperature;
Generating a subtraction value by subtracting the first air flow rate value from the second air flow rate value; And
Calculating nitrogen oxide emission of the diesel engine using the deduction value and nitrogen oxide emission according to an operating point of the diesel engine;
Diesel engine simulation method comprising a.
delete delete The method of claim 1,
Calculating a fuel flow rate of the diesel engine and an effective torque of the diesel engine according to a required torque of a driver and an engine speed of the diesel engine
Diesel engine simulation method comprising more.
delete The method of claim 1,
The exhaust gas pressure and temperature of the diesel engine
Determined according to the operating point of the diesel engine
How to simulate a diesel engine.
delete

Images