KR20050061121A - Exhaust gas recirculation controlling device of vehicle and method thereof - Google Patents

Abstract

To provide stabilization of the exhaust gas through the EGR feedback control of the vehicle using the information of the Nox sensor mounted on the exhaust side,

The process of calculating the fuel injection amount according to the operation information and applying it to the engine control while the engine is kept on, and determining whether the coolant temperature satisfies the EGR control condition, and if the EGR control condition is satisfied, the current operating area Calculating the final target Nox amount, calculating the final target Nox amount by applying a correction value including temperature conditions, controlling the EGR valve by calculating the control duty ratio for the final target Nox amount, and exhausting Determining whether there is a deviation from the final target Nox amount by detecting the actual amount of Nox contained in the gas, and if there is no deviation, maintains the current EGR control duty and, if there is a deviation, the control duty ratio applying the correction value for the deviation. Calculating and feedback controlling the EGR valve so that the target Nox amount is followed.

Description

Easy control device of vehicle and its method {EXHAUST GAS RECIRCULATION CONTROLLING DEVICE OF VEHICLE AND METHOD THEREOF}

The present invention relates to control of an exhaust gas recirculation (EGR) valve of a vehicle, and more particularly, to control an EGR feedback of an vehicle to provide stabilization of exhaust gas by using an EGR feedback control using information of a Nox sensor mounted on an exhaust side. An apparatus and a method thereof are provided.

For example, an EGR device applied to a vehicle is a device that suppresses the generation of Nox substances by recycling a part of the doubling gas back to the intake cylinder to lower the maximum temperature during combustion.

There are various EGR control methods applied to the conventional vehicle, but can be summarized into three broadly divided.

Firstly, the lift amount of the EGR valve is controlled. This is to determine the lift amount of the EGR valve in each operation region in advance, determine the current operation region, and extract the position control value determined for the corresponding operation region. This is how you control the amount.

In this case, the applied sensor is an EGR valve lift sensor mounted on the upper surface of the EGR valve, and the working fluid is controlled by using the negative pressure generated in the engine.

However, this control method has a disadvantage in that the amount of actual EGR flow fluctuates significantly when a predetermined driving range is changed between mass-produced vehicles or when the boost pressure and the back pressure change, resulting in a deviation of the exhaust gas.

Secondly, the virtual position of the EGR valve is controlled, which is a method of calculating the position of the virtual EGR valve using the duty ratio controlling the EGR valve and performing self-feedback control using the same.

However, this method also has a disadvantage in that a fixed duty ratio is applied to control the EGR valve as a result, and thus, as in the first lift control method, variations in the EGR flow due to deviation between vehicles cannot be prevented.

Third, a feedback control method using an air flow sensor is a method currently applied to most mass production vehicles.

This is a method of feedback control using the amount of air sensed by the air flow sensor mounted on the intake air (not the EGR flow but the actual clean air flowing from the outside).

That is, the target air amount is extracted by applying various correction values such as cooling water temperature, intake temperature, and intake pressure to the basic air amount according to the engine speed and fuel injection amount detected in the current operation area, and the current air amount detected by the air amount sensor is applied. The EGR valve is controlled to follow the target air amount based on the air amount.

At this time, the actual working fluid for the control of the EGR valve is used the negative pressure generated in the engine, this negative pressure is controlled in the solenoid valve.

When using this method, feedback control of the target air volume set in each operation area is known as the most accurate method at present. As a result, the actual EGR flow generates a lot of deviations between vehicles.

That is, even when the vehicle travels at the same speed due to the difference in frictional resistance and the difference in output between the vehicles, the driving region (engine rotational speed and fuel amount) shows a large variation.

Therefore, the target air volume set on the basis of this driving region shows a great difference even at the same speed, which results in a difference in the EGR flow.

EGR flow in the engine has the advantage of reducing NOx but has the disadvantage of increasing soot, which can cause serious soot quality problems when excessive EGR control is performed.

In addition, the mass-produced air flow sensor has a deviation of about 20% between the units.

In the prior art of feedback using an air flow sensor having such a deviation, it inevitably generates a deviation of 20% of the EGR flow, which may cause an EGR flow that may cause serious smoke problems in a production vehicle. Will mean.

Therefore, even when using this method, the variation of emissions between vehicles causes many quality problems in the actual vehicle production process.

The present invention has been invented to solve the above problems, the object of which is to calculate the target Nox amount for the current operating area, and to follow the target Nox amount by feedback applying the signal of the Nox sensor mounted on the exhaust side By controlling the EGR valve, the exhaust gas is stabilized.

The present invention for achieving the above object is a means for detecting the driving information of the vehicle; Means for detecting the amount of Nox material contained in the exhaust gas; Means for driving the EGR valve by a control duty; Calculate the target Nox amount for the current operating area and control the EGR valve with the control duty for it, and feedback-detect the actual amount of Nox substance contained in the exhaust gas so that the amount of Nox contained in the exhaust gas follows the target Nox amount. And means for feeding back control of the EGR valve.

The present invention includes the steps of calculating the fuel injection amount according to the driving information in the state where the engine is maintained on start and apply to the engine control; Determining whether the cooling water temperature satisfies the EGR control condition; Calculating a target Nox amount for the current driving region when the EGR control condition is satisfied, and calculating a final target Nox amount by applying a correction value including temperature conditions thereto; Controlling an EGR valve by calculating a control duty ratio for the final target Nox amount; Determining whether there is a deviation from the final target Nox amount by detecting the actual Nox amount contained in the exhaust gas; Maintaining a current EGR control duty if there is no deviation, and calculating a control duty ratio to which a correction value for the deviation is applied if there is a deviation so as to feedback-control the EGR valve to follow the target Nox amount. It provides a method of controlling an RG of a vehicle.

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

As can be seen in FIG. 1, an IG control apparatus for a vehicle according to the present invention includes a driving information detector 10, a Nox sensor 20, a controller 30, and a solenoid valve 40.

The driving information detector 10 detects the current driving information to determine the driving area and calculate the target Nox amount.

The detected operation information includes information on the engine speed from the crank angle, information on the amount of air sucked from the AFS (Air Flow Sensor) mounted at a predetermined position of the intake manifold, information on atmospheric pressure, and intake temperature. Information on the intake pressure, information on the temperature of the coolant, and the like.

The Nox sensor 20 is installed on the exhaust side, detects the concentration of the Nox substance contained in the exhaust gas, and feeds back information on the information to the control unit 30.

The controller 30 controls the EGR valve by calculating the target Nox amount in the current driving area according to the information of the driving information detector 10, and the amount of Nox included in the exhaust gas according to the feedback detected Nox signal. The EGR valve is controlled to follow the amount of this target Nox.

The solenoid valve 40 is controlled according to the duty control signal applied from the controller 30 so that the Nox material contained in the exhaust gas follows the target amount.

Through the present invention of the configuration including the function as described above, the operation of executing the RG control is as follows.

As can be seen in FIG. 2, when the engine is maintained, the control unit 30 controls the general driving information of the vehicle through the driving information detector 10, that is, the engine speed, atmospheric pressure, intake temperature, intake pressure, and cooling water. Information about the temperature and the like is detected (S101).

Subsequently, the basic fuel injection amount is calculated according to the detected operation information, the engine speed, and the air amount, and the final fuel injection amount is determined by applying correction values in consideration of information such as atmospheric pressure, intake temperature, intake pressure, and coolant temperature. Apply to (S102).

As described above, it is determined whether the EGR control condition, preferably the condition of the temperature of the coolant, is equal to or higher than the set reference temperature in the state where the control of fuel injection is performed according to the current operation information (S103).

If it is determined that the EGR control condition is satisfied in the above, the target Nox amount for the current operating area is calculated (S104), and the correction value according to the temperature condition of the coolant is calculated (S105). After calculating the Nox amount, the EGR control duty ratio is calculated accordingly (S106).

The target Nox amount is calculated under the conditions of the current engine speed and the air amount.

When the calculation of the EGR control duty ratio is completed as described above, the solenoid valve 40 is duty-controlled so that the amount of Nox included in the exhaust gas can follow the target Nox amount set for the current operation region (S107).

In the state where the EGR control is executed as described above, the control unit 30 detects the amount of the Nox substance contained in the exhaust gas by feedback from the Nox sensor installed on the exhaust side (S108) and detects a deviation from the target Nox amount (S109). ).

The above deviation is detected by {target Nox amount-actual measured Nox amount} x control variable.

In step S109, it is determined whether there is a deviation between the target Nox amount and the actual detected Nox amount in the current driving area (S110). If the deviation does not occur, the current EGR control duty is maintained. By returning to and recalculating and applying the correction value according to the deviation, the above-described process is repeated to feedback control so that the actual Nox amount contained in the exhaust gas follows the target Nox amount.

As described above, the present invention controls the EGR through the application of feedback of the amount of Nox contained in the exhaust gas, thereby eliminating variations in the exhaust gas and providing stabilization of the emission.

In addition, the cost competitiveness is improved by eliminating parts that are over-designed to reduce manufacturing costs.

1 is a schematic configuration diagram of an easy-to-control device of a vehicle according to the present invention.

2 is a flow chart of an embodiment for performing easy R control in a vehicle according to the present invention.

Claims (6)

Means for detecting driving information of the vehicle; Means for detecting the amount of Nox material contained in the exhaust gas; Means for driving the EGR valve by a control duty; Calculate the target Nox amount for the current operating area and control the EGR valve with the control duty for it, and feedback-detect the actual amount of Nox substance contained in the exhaust gas so that the amount of Nox contained in the exhaust gas follows the target Nox amount. Means for controlling the feedback of the EGR valve to the vehicle. The method of claim 1, And the target Nox amount is calculated from the information on the engine speed and the amount of air. The method of claim 1, And the EGR control duty is determined as a value to which a correction value including a temperature condition is applied to the target Nox amount. The method of claim 1, And the driving information includes engine speed, air amount, cooling water temperature, intake temperature, and intake air pressure information. Calculating a fuel injection amount according to the driving information while the engine is kept on and applying it to engine control; Determining whether the cooling water temperature satisfies the EGR control condition; Calculating a target Nox amount for the current driving region when the EGR control condition is satisfied, and calculating a final target Nox amount by applying a correction value including temperature conditions thereto; Controlling an EGR valve by calculating a control duty ratio for the final target Nox amount; Determining whether there is a deviation from the final target Nox amount by detecting the actual Nox amount contained in the exhaust gas; Maintaining a current EGR control duty if there is no deviation, and calculating a control duty ratio to which a correction value for the deviation is applied if there is a deviation so as to feedback-control the EGR valve to follow the target Nox amount. Easy control method of the vehicle. The method of claim 5, The target Nox amount is calculated from the conditions of the engine speed and the air amount, and the correction amount is calculated including the conditions of the temperature, intake temperature, intake pressure, and feedback Nox amount.