KR100440335B1 - a method for a reduction of engine exhaust gas in vehicle - Google Patents

Abstract

The present invention aims to precisely control the catalytic heating function by improving the target engine speed and the target ignition timing follow-up according to the idle speed actuator and the air-fuel ratio change amount in the vehicle engine;

Determining whether a catalyst heating condition is satisfied in the vehicle engine; Calculating a required low speed torque; Calculating a required high speed torque; Determining whether to control the air-fuel ratio; Calculating an engine total efficiency; Calculating an idle speed actuator duty amount by calculating a compensating low speed torque; Comprising the step of calculating the ignition timing perception, there is an effect that can reduce the emission gas and improve the idle operation.

Description

{A method for a reduction of engine exhaust gas in vehicle}

The present invention relates to a method for reducing the exhaust gas of a vehicle engine, and more particularly, to a method for reducing the exhaust gas of a vehicle engine that can increase the exhaust gas reduction effect by controlling the idle actuator operation in the vehicle engine.

As the emission regulations of vehicles are tightened, it is necessary to reduce the time to reach the maximum rise temperature of the catalyst (about 350 ° C.) and increase the catalyst efficiency as soon as possible to reduce the emissions. For this purpose a catalytic heating function is used.

The catalyst heating function is to increase the exhaust gas temperature immediately after starting the engine, particularly in an idle section, so that the exhaust gas passes through the catalyst to quickly increase the catalyst temperature. To achieve this, the idle speed actuator control duty is increased in the idle section to increase the target rotation speed and delay the ignition timing.

Therefore, in the idle section immediately after starting the engine, the friction between the engine and the accessory is reduced, and the friction between the oils is rapidly reduced. That is, the fluctuation of the torque loss of the engine greatly occurs. In this section, since the heating of the oxygen sensor is completed and the sensor is ready, the air-fuel ratio control is executed. Therefore, much faster control than the normal idle control is required, and the engine torque compensation according to the air-fuel ratio fluctuations is required while entering the air-fuel ratio control from injection control.

For this reason, conventionally, the idle control PID-coefficient and the general control PID-coefficient of the catalyst heating section are easy to follow the target rotation speed in the general idle section, but the variation in engine torque loss in the catalyst heating section is shown in FIG. 1. As described above, the target rotational speed is poor, and when the air-fuel ratio control enters, there is no torque compensation due to the variation in the air-fuel ratio, so that the target rotational speed is poor, thereby causing a problem of excessive emissions.

That is, when the fuel amount is injected and controlled, the target rotational speed followability is good, but the engine rotational speed cannot follow the target rotational speed while entering the air-fuel ratio control, which causes a problem of excessive emission of exhaust gas.

In addition, as the engine speed increases with respect to the target speed, the amount of ignition timing perception decreases, causing an increase in the exhaust gas temperature. Therefore, there is a problem in that the exhaust gas excess phenomenon is caused by delaying the time of reaching the maximum rise temperature of the catalyst.

Accordingly, an object of the present invention is to solve the above problems, and for a vehicle that can precisely control the catalytic heating function by improving the target engine speed and the target ignition timing followable according to the idle speed actuator and the air-fuel ratio change amount in the vehicle engine. It is to provide a method for reducing the exhaust gas of the engine.

1 is a graph illustrating an operation of an engine by a method for reducing exhaust gas of a conventional vehicle engine

2 is a block diagram of an exhaust gas reducing device of a vehicle engine according to an embodiment of the present invention,

3 is a flowchart illustrating a method for controlling emission reduction of a vehicle engine applied to the present invention.

<Description of Symbols for Main Parts of Drawings>

100: vehicle operation state detection device 110: cooling water temperature detection unit

120: intake air temperature detection unit 130: throttle valve opening degree detection unit

140: engine speed detection unit 200: engine control device

300: idle driver

The present invention for achieving the above object,

Determining whether a catalyst heating condition is satisfied in the vehicle engine;

Calculating a required low speed torque;

Calculating a required high speed torque;

Determining whether to control the air-fuel ratio;

Calculating an engine total efficiency;

Calculating an idle speed actuator duty amount by calculating a compensating low speed torque;

Comprising the step of calculating the ignition timing perception amount.

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

2 is a configuration diagram of a device for reducing exhaust gas of a vehicle engine according to an exemplary embodiment of the present invention, and FIG. 3 is a flowchart illustrating a method for controlling exhaust gas reduction of a vehicle engine applied to the present invention.

As shown in FIG. 1, an exhaust gas reducing apparatus of a vehicle engine includes a vehicle operating state detection device 100 that detects a change in a vehicle operating state that varies according to a change in an operating state of a vehicle; After receiving the cooling water temperature, the intake air temperature, the throttle valve opening degree, and the engine speed detected by the vehicle operation state detecting device 100, the idle control is changed when the catalyst heating condition is satisfied, and the idle speed actuator duty and the ignition timing are determined. After calculating the torque change to calculate the ignition timing efficiency, calculate the air-fuel ratio efficiency according to the air-fuel ratio control conditions, and then calculate the total efficiency according to the calculated ignition timing efficiency, air-fuel ratio efficiency and fuel cut efficiency To calculate the idle speed actuator duty according to calculation of the compensated slow pass torque, and to determine the ignition time by using the calculated compensated slow pass torque and the ignition timing efficiency to output a predetermined emission control signal. Apparatus 200;

The idle control device 300 is driven in synchronization with a predetermined exhaust gas control signal output from the engine control device 200.

The vehicle operating state detection apparatus 100 includes a coolant temperature detection unit 110 for detecting a change in coolant temperature that varies according to a change in an operating state of a vehicle;

An intake air temperature detector 120 for detecting a change in air intake temperature introduced into the vehicle engine according to a change in an operation state of the vehicle;

A throttle valve opening degree detector 130 which detects a change in the throttle valve opening degree which is linked in accordance with the driver's accelerator pedal operation;

The engine speed detection unit 140 detects a change in engine speed that varies according to a vehicle operating state change.

With reference to the accompanying drawings, the exhaust gas reduction method of the vehicle engine having the above configuration will be described by way of example.

When the engine is started after the power is applied to the vehicle, the vehicle operation state detecting apparatus 100 detects a change in the coolant temperature, the intake air temperature, the throttle valve, and the engine speed which are varied according to the change in the vehicle operating state.

Therefore, the engine control apparatus 200 outputs a predetermined control signal to receive the coolant temperature, the intake air temperature, the throttle valve and the engine speed change, etc. applied from the vehicle operating state detection apparatus 100, and the vehicle operating state. The detection apparatus 100 outputs the detected coolant temperature, intake air temperature, throttle valve and engine speed change in synchronization with the control signal output from the engine control apparatus 200.

The engine control apparatus 200 receives the cooling water temperature, the intake air temperature, the throttle valve, the engine speed change, and the like, which are applied from the vehicle operation state detecting apparatus 100, and determines whether the catalyst heating condition is satisfied (S100).

The catalyst heating conditions are the engine idle state, the cooling water temperature and the intake air temperature is 25 ℃ or less.

When it is determined that the catalyst heating condition is satisfied, the engine control apparatus 200 changes the idle controller to set weights according to the cooling water temperature and the oil temperature in the general idle controller (S110).

The cooling water temperature and the oil temperature are the main factors that can reflect the torque loss.

Thereafter, the engine control apparatus 200 sets a torque reserve as data to the engine control apparatus 200 according to the target rotation speed and target ignition timing used for the catalyst heating (S120).

In the above, the larger the torque storage amount, the larger the target rotational speed. The target ignition timing is determined according to the torque storage amount and the ignition timing efficiency. The target rotational speed and ignition timing determine the minimum emissions area by normal and failure methods.

Subsequently, the engine control apparatus 200 calculates a required low path torque by summing the torque storage amount, the torque loss amount, and the idle control compensation torque amount set above (S130).

The required low speed torque above is used to determine the idle speed actuator control duty.

Subsequently, the engine control apparatus 200 calculates a required high speed torque (Fast Path Torque) which subtracts the torque reserve from the required low speed torque calculated above (S140).

The above required high speed torque is used for ignition timing control.

After that, the engine control apparatus 200 determines whether the air-fuel ratio control is executed after calculating the ignition timing efficiency (S150 and S160).

In the above, the ignition timing efficiency is the ratio of the required high speed torque to the maximum torque value at the current engine speed and the engine load.

Therefore, when it is determined that the air-fuel ratio control is executed in the above, the engine control apparatus 200 calculates the air-fuel ratio efficiency to reflect the torque fluctuation value as the ratio of the other torque fluctuations to the air-fuel ratio, and calculates the ignition timing efficiency and the air-fuel ratio efficiency calculated above. And calculating the total efficiency of the engine by multiplying the fuel cutoff efficiency (S170 and S180).

In the above, the fuel cutoff efficiency is zero.

That is, as fuel is not supplied by the fuel supply cutoff control signal, the expression of the control state is expressed as 0, which means that there is no fuel cutoff efficiency.

Therefore, the total efficiency of the engine is calculated by calculating only the calculated ignition timing efficiency and air-fuel ratio efficiency excluding fuel cutoff efficiency.

However, if the air-fuel ratio control is not executed in the above, the engine control apparatus 200 calculates the engine total efficiency only with the ignition timing efficiency without calculating the air-fuel ratio efficiency.

Accordingly, by calculating the total efficiency of the engine in the above, the engine control apparatus 200 divides the yoke low speed torque calculated in S130 by the total efficiency of the engine to calculate and calculate the compensated low speed torque, and then calculates the calculated low speed torque. The idle actuator duty is calculated according to the compensating low speed torque to output a predetermined control signal for controlling the idle actuator (S200).

In operation S210, the required high-speed torque and the ignition timing efficiency are calculated to calculate the ignition timing perception amount, and the ignition timing control signal is output according to the calculated value (S210).

Thus, by precisely controlling the idle speed actuator and the ignition timing as described above, and precisely controlling the catalyst heating function, the emission gas when driving the vehicle in the required engine driving region can be reduced, and the target engine speed tracking performance is good. Children's stability is improved.

As described above, the present invention improves the target engine speed and the target ignition timing follow-up according to the idle speed actuator and the air-fuel ratio change amount in the vehicle engine, thereby precisely controlling the catalyst heating function, thereby reducing emission and reducing idling operation. It has an effect.

Claims (9)

Determining whether a catalyst heating condition is satisfied in the vehicle engine; Calculating a required low speed torque; Calculating a required high speed torque; Determining whether to control the air-fuel ratio; Calculating an engine total efficiency; Calculating an idle speed actuator duty amount by calculating a compensating low speed torque; Comprising a step of calculating the ignition timing perception amount of the exhaust gas control method for an engine for a vehicle. The method of claim 1, wherein the catalyst heating condition is a condition in which the engine is an idle section and the cooling water temperature and the intake temperature are below a predetermined set reference temperature. The exhaust gas control method for a vehicle engine according to claim 1, wherein the required low speed torque is calculated as a sum of a torque storage amount, a torque loss amount, and an idle control compensation torque amount. The method of controlling exhaust gas of a vehicle engine according to claim 3, wherein the torque storage amount is a value in which required torque is set as data according to a target engine speed used for catalytic heating and a target ignition timing. The method of claim 1, wherein the required high speed torque is calculated by subtracting the torque storage amount from the required low speed torque amount. The exhaust gas control method of claim 1, wherein the engine total efficiency is calculated as a product of ignition timing efficiency, air-fuel ratio efficiency, and fuel cutoff efficiency. 2. The method of claim 1, wherein the compensating low speed torque comprises dividing a required low speed torque by an engine total efficiency. The method of claim 1, wherein the idle speed actuator duty amount is further determined according to the compensating low speed torque. The method according to claim 1, wherein the ignition timing perception amount is determined according to a value calculated using the required high speed torque and the ignition timing efficiency.