KR100428174B1 - NOx REDUCTION CONTROL METHOD FOR EARLY STAGE OF DIESEL ENGINE - Google Patents

Abstract

For the purpose of resolving the problem of initial excess NOx after starting the engine;

Setting an EGR fuel demand mode according to a total driving distance after receiving a fuel demand according to a fuel demand and an accelerator pedal opening degree in a vehicle in operation; Calculating a first target air amount according to the EGR fuel demand and the engine speed set in the step; Calculating an EGR monitoring value by calculating the first target air amount and the intake air amount calculated in the step; Computing the second target air amount by calculating the EGR monitoring value and the accelerator pedal operation state change value calculated in the above step, and outputting the predetermined predetermined EGR valve control signal. It can prevent the occurrence of excessive NOx problem, improve fuel economy, and reduce the cost.

Description

NOx REDUCTION CONTROL METHOD FOR EARLY STAGE OF DIESEL ENGINE}

The present invention relates to a diesel engine, and more particularly, to provide a method for reducing soot at initial start-up of a diesel engine to reduce an increase in NOx generation generated through exhaust gas recirculation (EGR) control at the start of a diesel engine. It is to.

In order to prevent air pollution, the emission of nitrogen oxides (NOx) from automobile emissions is regulated by law. Nitrogen oxides (NOx) are generated by the reaction of nitrogen and oxygen in the air at high temperature during combustion in the cylinder. Higher concentrations of nitrogen oxides (NOx) are emitted as the combustion temperature increases.

Reducing the generation of NOx by introducing the exhaust gas once again into the combustion chamber and reducing the combustion temperature is called an EGR, that is, an exhaust gas recirculation system. It is important to adjust the amount according to the engine operating area.

In particular, since the EGR system of the electronically controlled diesel engine can set the EGR rate according to the operating conditions, a large amount of EGR is frequently used.

The EGR valve is provided with a position sensor for detecting the lift position of the valve, and the electronics for turning on and off the pressure applied to the diaphragm chamber so as to be the valve lift position in accordance with a predetermined program according to the rotational speed and load of the engine. Control by changing the duty ratio of the valve.

In addition, considering the operability and the heat resistance of the exhaust system parts, the EGR effect is achieved by introducing air into the diaphragm chamber with the ON and OFF solenoid valves according to the throttle opening degree and engine speed conditions in the idle, full load, and high rotational speeds. Stop it.

Therefore, in the related art, the opening degree of the EGR valve is adjusted to follow the target air amount by using an EGR map consisting of engine speed-fuel amount-target air amount with data of an air flow sensor (used for calculating the target air amount), target fuel amount, and engine speed. By controlling the opening degree of the desired EGR valve, the desired EGR rate is controlled.

However, in the conventional method described above, even if the same emission mode is driven according to various friction changes in the state of taming from the initial state and in the deterioration of the vehicle, the engine driving area is actually changed (the engine speed is the same, but the amount of fuel is the same). Is changed) By controlling with the same EGR map, problems such as an increase in initial soot (especially NOx) are included.

Accordingly, an object of the present invention is to solve the above problems, to provide a method for reducing the smoke during initial start-up of a diesel engine to increase the development target value to solve the problem of excessive initial exhaust (NOx) after starting the engine. will be.

The present invention for achieving the above object,

Setting an EGR fuel demand mode according to a total driving distance after receiving a fuel demand according to a fuel demand and an accelerator pedal opening degree in a vehicle while driving;

Calculating a first target air amount according to the EGR fuel demand and the engine speed set in the step;

Calculating an EGR monitoring value by calculating the first target air amount and the intake air amount calculated in the step;

And calculating the second target air amount by calculating the EGR monitoring value and the accelerator pedal operation state change value calculated in the above step, and outputting a corresponding predetermined EGR valve control signal.

1 is a block diagram of the configuration of the smoke reduction control device at the initial start of the diesel engine according to the present invention,

2 is a flowchart illustrating a method of controlling smoke reduction at initial startup of a diesel engine according to the present invention.

<Description of Symbols for Main Parts of Drawings>

100: vehicle operation state detection device 110: engine speed detection unit

120: accelerator pedal opening degree detection unit 130: intake air amount detection unit

140: vehicle speed detection unit 200: engine control device

300: drive device

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

1 is a block diagram illustrating a configuration of a control device for reducing smoke during initial start-up of a diesel engine according to the present invention, and the vehicle operating state detecting apparatus 100 detects a signal that varies according to a change in an operating state of a vehicle.

The engine control apparatus 200 receives a signal applied by the vehicle operating state detection apparatus 100 and receives a fuel demand amount according to the fuel demand amount and the accelerator pedal opening degree in the vehicle while driving, and then, depending on the total driving distance, After setting the fuel demand mode, after calculating the first target air amount according to the set EGR fuel demand and the engine speed, the calculated first target air amount and the intake air amount are calculated to calculate the EGR monitoring value. And a predetermined EGR valve control signal corresponding to the second target air amount calculated by calculating the accelerator pedal operation state change value.

The driving device 300 controls the operation of the EGR valve in synchronization with a predetermined EGR valve control signal output from the engine control device 200, and adjusts the amount of air accordingly.

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

An accelerator pedal opening degree detector 120 which detects a change in an accelerator pedal opening degree that is changed according to an accelerator pedal operation state of a driver;

An intake air amount detection unit 130 for detecting a change in intake air amount varying according to a change in an operation state of the vehicle;

The vehicle speed detection unit 140 detects a change in vehicle speed that varies according to a change in an operation state of the vehicle.

A description will be given with reference to FIG. 2 to which a method for controlling soot reduction at initial start-up of a diesel engine having the above-described configuration is attached.

When power is applied to the vehicle, the vehicle operating state detecting apparatus 100 detects an engine speed, an accelerator pedal opening degree, an intake air amount, a vehicle speed, and the like according to a change in the operating state of the vehicle.

Accordingly, when the engine control device 200 outputs a predetermined control signal to receive the engine speed, the accelerator pedal opening degree, the intake air amount and the vehicle speed detected by the vehicle operation state detection device 100, the vehicle operation state detection device The engine 100 outputs the detected engine speed, the accelerator pedal opening degree, the intake air amount, the vehicle speed, and the like, in synchronization with a predetermined control signal output from the engine control apparatus 200.

The engine control apparatus 200 receives an engine speed, an accelerator pedal opening degree, an intake air amount, a vehicle speed, and the like, which are output from the vehicle operation state detection apparatus 100, and is operated according to an initially set fuel demand and a vehicle driving state of a driver. The fuel demand amount EGR_Fuel is calculated from the predetermined EGR fuel demand amount map set in the memory according to the accelerator pedal opening degree (S100 and S110).

As described above, as the fuel demand amount EGR_Fuel is calculated, the engine control apparatus 200 determines whether the total travel distance of the vehicle is less than or equal to a predetermined reference value (for example, 5000 miles) (S120).

That is, after the vehicle leaves the factory, the driver drives the vehicle and starts to tame the operating state of the engine.

Accordingly, the engine control apparatus 200 classifies the time point at which the break-in of the vehicle is finished according to the mileage, and performs the EGR control to adjust the fuel injection amount based on the time point when the total mileage reaches a predetermined reference value. .

Therefore, when it is determined that the total mileage of the vehicle is less than or equal to a predetermined reference value (for example, 5000 miles), the engine control apparatus 200 sets the fuel demand amount (EGR_Fuel_mod) initially for the EGR control and the fuel demand amount and the driver. The fuel demand amount ERG_Fuel calculated from the predetermined EGR fuel demand map set in the memory according to the accelerator pedal opening degree manipulated according to the vehicle driving state of the engine is multiplied by calculating and applying the taming effect value Aging_effect of the engine demand fuel amount ( S130).

However, when it is determined in S120 that the total mileage of the vehicle is equal to or greater than a predetermined reference value (for example, 5000 miles), the engine control apparatus 200 initially sets the fuel demand amount (EGR_Fuel_mod) for the EGR control. The fuel demand amount ERG_Fuel calculated from the predetermined EGR fuel demand amount map set in the memory according to the demand amount and the accelerator pedal opening degree manipulated according to the driver's vehicle driving state is applied (S140).

That is, after the vehicle is released, the fuel demand amount (EGR_Fuel_mod) for the EGR control is set in the memory according to the fuel demand amount initially set in accordance with the initial demand and the accelerator pedal opening degree of the driver. It is calculated by the fuel demand amount (EGR_Fuel) calculated from the EGR fuel demand map of to maintain the constant change in the value of the first target air amount (AMF_Demand) caused as the engine demand fuel amount changes as the taming occurs.

Therefore, the value of the first target air amount AMF_Demand is used instead of the fuel demand amount EGR_Fuel_mod for the EGR control calculated above (S150).

As a result, the same target air volume value, that is, the EGR control rate, may be prevented under the same vehicle condition regardless of the vehicle breaking-in state.

As described above, the present invention increases the development target value to solve the problem of excessive NOx after starting the engine, thereby preventing occurrence of NOx excess problem of the initial vehicle, and improving fuel economy. Cost savings can be achieved.

Claims (2)

Setting an EGR fuel demand mode according to a total driving distance after receiving a fuel demand according to a fuel demand and an accelerator pedal opening degree in a vehicle while driving; Calculating a first target air amount according to the EGR fuel demand and the engine speed set in the step; Calculating an EGR monitoring value by calculating the first target air amount and the intake air amount calculated in the step; Calculating the second target air amount by calculating the EGR monitoring value and the accelerator pedal operation state change value calculated in the step, and outputting a corresponding predetermined EGR valve control signal. Soot reduction control method. According to claim 1, If the total mileage of the vehicle is less than a predetermined set reference value, the fuel demand for the EGR control is set in the memory according to the accelerator pedal opening degree manipulated in accordance with the initially set fuel demand and the vehicle driving state of the driver Multiplying and calculating the value of the taming effect of the engine demand fuel amount by the fuel demand amount calculated in the predetermined EGR fuel demand map; In this step, if the total mileage of the vehicle is equal to or less than a predetermined set reference value, the fuel demand for EGR control is set to a predetermined EGR fuel set in a memory according to an initially set fuel demand and an accelerator pedal opening degree manipulated according to the driver's vehicle driving state. A method for reducing soot at initial start-up of a diesel engine, characterized in that it is applied to a value calculated from fuel demand in a demand map.