KR20060070198A - Method for calculating of the guantity of soots in emission - Google Patents

Abstract

Calculate accurate and simplified dynamic smoke variation using the combustion characteristics of diesel engines whose function is closely related to smoke emissions and air-fuel ratios in diesel engines to prevent excessive accumulation of smoke in DPF, improve driving performance and improve vehicle fuel economy For the purpose of doing so;

A diesel engine for a vehicle, comprising: receiving data of an engine speed, a fuel injection amount, and an oxygen amount, the engine speed being varied according to an operating condition after the diesel engine is started; Setting smoke emission and oxygen concentration in a steady state in the memory map data based on the data input in the step; Calculating a difference between the oxygen concentration set in the step and the input oxygen concentration, and setting a smoke increase amount in the dynamic smoke map accordingly; And calculating a new dynamic smoke amount by calculating the map data set in the step and the input oxygen concentration by the set program.

Engine control unit, oxygen quantity, smoke map, oxygen concentration, engine speed

Description

Method for calculating of the guantity of soots in emission

1 is a block diagram of a vehicle engine control apparatus according to the present invention;

2 is a flowchart illustrating a method of calculating a dynamic smoke emission amount of a vehicle engine applied to the present invention.

3 is a graph illustrating an oxygen content map and a smoke map in a steady state according to the present invention;

4 is a graph showing the amount of change of smoke according to the change in oxygen concentration according to the present invention.

※ Explanation of code for main part of drawing

100: vehicle operating state detection means 110: engine speed detection unit

120: engine required injection amount detection unit 130: oxygen amount detection unit

200: engine control means 300: driving means

The present invention relates to a method for controlling a diesel engine, and more particularly, to a method for calculating dynamic smoke emission of a diesel engine to provide a method for calculating an accurate smoke emission according to a driving condition of a vehicle in a diesel engine vehicle.

In general, in the development of vehicle engines, in order to meet the stringent emission regulations and to develop eco-friendly passenger diesel engines, the installation of diesel particuate filters (DPFs) is essential. In addition to the amount of smoke (SOOT) of the smoke, the amount of smoke emitted from the engine must be accurately calculated.

Therefore, in the related art, when the vehicle is accelerated or decelerated without being driven at a constant speed, the amount of air introduced into the engine is different from the amount of air introduced under the steady state driving conditions, so that the air-fuel ratio condition in the combustion chamber where actual combustion occurs is different from the normal state. . If the air-fuel ratio conditions are different, the amount of smoke emitted increases or decreases than that emitted in the normal state. The amount of smoke increased or decreased in the dynamic state is estimated as a function of the amount of change in the required injection amount representing the degree of deceleration. Therefore, in calculating dynamic smoke emissions, the smoke map stored in the memory of the engine control unit is constructed from the smoke values measured while maintaining the angular speed and fuel condition conditions of the engine. And the dynamic smoke function is obtained by measuring the change in smoke emissions according to the rate of change of injection volume under dynamic test conditions. Under certain vehicle driving conditions, the steady state value obtained from the smoke map and the increase of the dynamic state obtained from the dynamic smoke function can be added to calculate the smoke emission considering the dynamic state.

However, in the conventional method described above, the magnitude of the smoke increase / decrease in the non-dynamic operating conditions versus the amount of smoke discharged in the steady state operating conditions is greatly influenced by the factors described below as well as the magnitude of the rate of change of the required injection amount. In other words, the factors affecting the smoke emission in the dynamic state are the fuel amount variation between the injectors, the intake duct, the air cleaner, the intercooler hose and pipe, the intercooler, the turbocharger specification, the turbocharger control factor of the engine control unit, the engine speed and the like. Injection amount and the like. Due to the influence of the above factors, the amount of smoke increase actually appears differently with respect to the hourly rate of change of the same required injection amount, thereby increasing the error of the smoke emission calculation. The larger the error in the smoke emission calculation, the worse the DPF durability and the fuel economy of the vehicle. In addition, since each vehicle has its own dynamic smoke function, the development period is long, the development cost is excessive, and even if the same vehicle is used, the response characteristics of the acceleration turbocharger are different for each driving area of the engine. Using the same dynamic smoke function in D reduces the accuracy of dynamic smoke emission calculations.

Accordingly, the present invention has been made to solve the above-mentioned conventional problems, by calculating the accurate and simplified dynamic smoke change amount by using the combustion characteristics of the diesel engine having a close function of smoke emissions and air-fuel ratio in the diesel engine smoke It is to provide a method for calculating the dynamic smoke emission of a diesel engine that can prevent excessive accumulation in the DPF, improve driving performance and improve vehicle fuel economy.

The present invention for achieving the above object,

In a vehicle diesel engine,

After starting the diesel engine, receiving data of an engine speed, a required fuel injection amount and an oxygen amount varying according to an operating condition;

Setting smoke emission and oxygen concentration in a steady state in the memory map data based on the data input in the step;

Calculating a difference between the oxygen concentration set in the step and the input oxygen concentration, and setting a smoke increase amount in the dynamic smoke map accordingly;

And calculating a new dynamic smoke amount by calculating the map data set in the step and the input oxygen concentration by a set program.

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

1 is a block diagram illustrating a configuration of a dynamic smoke emission control apparatus for a diesel engine according to the present invention, and FIG. 2 is a flowchart illustrating a method for calculating dynamic smoke emission of a vehicle engine applied to the present invention.

As shown in FIG. 1, a dynamic smoke emission control apparatus for a diesel engine includes a vehicle operating state detection device 100 that detects an engine speed, a fuel injection amount, and an oxygen amount that vary according to a change in an operating state of a vehicle;

Based on the input engine speed, fuel demand injection amount and oxygen amount detected and applied by the vehicle operation state detection device 100, the smoke emission and oxygen concentration in the steady state are set in the memory map data, and Calculate the difference between the set oxygen concentration and the input oxygen concentration, set the smoke increase amount in the dynamic smoke map accordingly, and calculate the new dynamic smoke amount by calculating the set map data and the input oxygen concentration by the set program. An engine control device 200;

The driving device 300 is configured to adjust the amount of fuel injected into the engine internal combustion chamber in synchronization with a control signal applied from the engine control device 200.

The vehicle operating state detecting apparatus 100 includes an engine speed detecting unit 110 for detecting a change in rotational speed of an engine that is changed according to a change in an operating state of a vehicle;

A fuel required injection amount detection unit 120 for detecting a required injection amount injected into the engine internal combustion chamber according to a change in the operation state of the vehicle;

According to the change in the operating state of the vehicle is provided in the discharger pipe of the rear end of the turbocharger is composed of an oxygen amount detector 130 for detecting the amount of oxygen contained in the exhaust gas discharged from the engine.

It will be described with reference to Figure 2 attached to the dynamic smoke emission calculation method of the diesel engine according to the present invention having the above configuration.

The main causes of the difference between the smoke emission in the dynamic state and the smoke emission in the steady state in diesel vehicles are the time difference caused by the air inertia in the intake duct, air cleaner, intercooler hose and pipe, and the intercooler and the supercharge pressure due to the turbocharger dynamic inertia. Because of the time difference.                     

This time difference causes the air-fuel ratio condition in the combustion chamber to be different from the normal state at the same engine condition, that is, the same engine speed and the required fuel amount, and the air-fuel ratio condition is different from the steady-state.

Therefore, in the accurate and simplified dynamic smoke change calculation logic using the combustion characteristics of the diesel engine having a close function of smoke emission and air-fuel ratio, it has calculation logic that uses the concentration of the oxygen sensor.

In the case of the diesel engine equipped with the DPF applied in the present invention, the exhaust pipe is provided with an oxygen amount detection sensor. Therefore, the amount of smoke change in the diesel engine depends on the injection pressure, the injection timing, the EGR rate, the boost pressure, the pilot injection amount, etc. according to the operating conditions as well as the oxygen concentration. Including the injection pressure, the injection timing, the ERG rate, the boost pressure, the post injection amount, and the like in the calculation logic can increase the accuracy of the smoke emission calculation. However, this becomes a problem of increasing the calculation capacity and load of the engine control device 200, so that the above factors can be represented simply by introducing the required injection amount and applying it to the calculation logic of the present invention as follows.

Therefore, the method of calculating the correction value of the dynamic smoke amount of this invention consists of an example as follows.

When the driver applies power to the vehicle to drive the vehicle having the diesel engine, the engine controller 200 initializes all functions. Thereafter, when the driver starts the engine, the engine control apparatus 200 outputs a fuel injection control signal according to the fuel injection amount set in the memory (S100).

Subsequently, the engine control apparatus 200 receives an engine speed, a fuel required injection amount, and an oxygen amount, which are varied according to the operation state of the vehicle, from the vehicle operation state detection device 100 (S110).

With the engine speed and fuel demand injection amount and oxygen amount inputted above, the engine control apparatus 200 sets the steady state smoke emission and oxygen amount concentrations in the oxygen amount map and the smoke map stored in the memory as shown in FIG. 3. (S120, S130).

FIG. 3 is an example of visualizing oxygen concentration and smoke emission obtained through a test in a steady state in an ISO-LINE. Therefore, a map table of oxygen concentration and smoke emissions stored in the memory can be created with the horizontal axis as the engine speed and the vertical axis as the required injection amount of fuel.

)에서 터보차저 후단의 배기파이프에 구비된 산소량 검출센서로부터 입력되는 현재의 산소량 농도(

)를 연산하여 그 차를 산출한다(S140). In the above-described oxygen amount map and smoke map stored in the memory, the steady state smoke discharge and the oxygen amount concentration are set, and the engine control apparatus 200 sets the oxygen amount concentration in the normal state (

Current concentration of oxygen input from the oxygen detection sensor included in the exhaust pipe after the turbocharger

) And calculates the difference (S140).

When calculating the difference of the oxygen content concentration can be expressed by the following equation (1).                     

Subsequently, the engine control apparatus 200 reduces the oxygen concentration in the dynamic smoke map stored in the memory as shown in FIG. 4 by using the difference between the steady state oxygen amount concentration and the current oxygen amount concentration calculated above. The smoke increase amount according to the difference is set (S150).

FIG. 4 is a graph illustrating a test result of smoke emission according to a change in oxygen concentration at typical points of the exhaust gas control region. Under all conditions, as the oxygen concentration decreases, the smoke emission increases nonlinearly, and the following Equation 2 is established.

)에 정상상태의 산소량 농도와 센서의 산소농도의 차이(

)를 곱셈 연산하면 산소농도 변화에 따른 스모크량 증가량을 얻을 수 있고 여기에 스모크 맵에서 설정한 정상상태의 스모크 배출량(

)을 더하면 정확한 동적 스모크량 보정치(

)를 산출할 수 있다(S160).Subsequently, when the smoke increase amount according to the oxygen concentration decrease difference is set in the dynamic smoke map of FIG. 4, the engine control apparatus 200 sets the smoke increase amount (

Difference between the steady-state oxygen concentration and the oxygen concentration of the sensor

Multiply) to obtain the amount of smoke increase according to the change in oxygen concentration, and to the steady state smoke emission set in the smoke map (

) Plus the correct dynamic smoke amount correction (

May be calculated (S160).

When the above process is illustrated by Equation 3, Equation 3 below.

)를 산출함으로서, 엔진 제어 장치(200)는 DPF 내에 스모크 과다 축적을 방지하기 위하여, 엔진 실린더 내부로 분사되는 연료 분사량을 제어하기 위한 제어신호를 구동장치(300)로 출력한다.As described above, the accurate dynamic smoke correction value (

In order to prevent excessive accumulation of smoke in the DPF, the engine control apparatus 200 outputs a control signal for controlling the fuel injection amount injected into the engine cylinder to the driving apparatus 300.

Therefore, the driving device 300 is synchronized with the control signal output from the engine control device 200 to adjust the amount of post injection injected into the engine cylinder.

As a result, excessive accumulation of smoke in the DPF can be prevented, thereby preventing breakage of the DPF.

As described above, the dynamic smoke emission calculation method of the diesel engine according to the present invention calculates an accurate and simplified dynamic smoke correction value using the combustion characteristics of the diesel engine having a close functional relationship between the smoke emission and the air-fuel ratio in the diesel engine. By controlling the fuel injection amount, it is possible to prevent excessive accumulation of smoke in the DPF, to prevent the breakage of the DPF, to increase the regeneration period of the DPF, and to improve driving performance while improving vehicle fuel economy. It can work.

In addition, since the smoke concentration change due to the mass production deviation of the injector, the boost pressure sensor, the air flow meter, etc. can be considered through the oxygen concentration measurement, the smoke emission in the steady state can be more accurately identified.

Furthermore, since the same test data can be applied to the vehicle to which the same engine is applied, the vehicle development period can be shortened.

Claims (2)

In a vehicle diesel engine, After starting the diesel engine, receiving data of an engine speed, a required fuel injection amount and an oxygen amount varying according to an operating condition; Setting smoke emission and oxygen concentration in a steady state in the memory map data based on the data input in the step; Calculating a difference between the oxygen concentration set in the step and the input oxygen concentration, and setting a smoke increase amount in the dynamic smoke map accordingly; And calculating a new dynamic smoke amount by calculating the map data set in the step and the input oxygen concentration by a set program. The method of claim 1, A method for calculating the dynamic smoke emission of a diesel engine, wherein the required fuel injection amount is a representative factor of injection pressure, injection timing, EGR rate, boost pressure, and post injection amount.

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