KR20030087703A - Apparatus for controlling post injection of common rail injection system in diesel vehicle and method thereof - Google Patents

Abstract

PURPOSE: An apparatus and a method are provided to achieve improved reliability of system, while reducing costs by performing a post injection without using an additional injection device. CONSTITUTION: An apparatus comprises an engine information detection unit for detecting information required for controlling an engine when the engine is turned on; a control unit(70) for calculating the required post injection fuel amount by analyzing the detected information of the engine, and controlling a post injection operation in consideration of the fuel pressure in the common rail; and an injector(80) which is open/shut for a preset time period in accordance with the control signal applied from the control unit, and injects the fuel of the amount of the calculated post injection. The engine information detection unit includes a pressure detection portion(10) for detecting pressure of the common rail, an engine RPM detection portion(20), a coolant temperature detection portion(30), an atmospheric pressure detection portion(40), a catalyst temperature detection portion(50), and an intake- air amount detection portion(60).

Description

After injection fuel amount control device and method of diesel common rail injection system {APPARATUS FOR CONTROLLING POST INJECTION OF COMMON RAIL INJECTION SYSTEM IN DIESEL VEHICLE AND METHOD THEREOF}

The present invention relates to a diesel common rail injection system, and more particularly, to control the after injection amount of the diesel common rail injection system for the calculation of the amount of post injection fuel for activation and regeneration of the purification system (catalyst) and the control of the injection holding time. An apparatus and method are provided.

In general, the diesel engine is very economical compared to the gasoline engine, the fuel economy is used in a variety of applications, and is currently being used in RV vehicles and passenger cars, the scope of application is rapidly expanding.

In order to apply a diesel engine to a passenger car, miniaturization and high speed must be accompanied. However, as miniaturization and high speed operation are performed, the time and space of fuel and air mixing are reduced, which leads to a lot of difficulties in optimizing the flow field and the spraying station.

In order to solve this problem, a common rail injection system is provided in which electron atomization and high pressure technology are applied to a fuel injection system to control fuel atomization, proper timing and injection amount of fuel.

The common rail injection system provides high pressure injection compared to the low pressure injection by the conventional cam driving method, and precisely control the injection timing to improve fuel efficiency and stabilize the exhaust gas.

The injection method of the common rail injection system includes pilot injection, main injection, and post injection. Pilot injection is performed by injecting fuel before the main injection is performed. Promotes good combustion, reduces noise caused by direct injection, reduces emissions and stabilizes combustion. Main injection is to generate actual engine output. Engine torque, engine speed, cooling water temperature, intake temperature, The injection amount is determined by the conditions such as atmospheric pressure.

The post-injection is an injection following the main injection, which injects the amount of fuel calculated during the period of up to 200 DEG in the expansion stroke or the exhaust stroke to the exhaust gas side.

Unlike the pilot injection or the main injection, the injected fuel is evaporated by the residual heat of exhaust gas instead of being burned in the cylinder, recycled to the combustion chamber through the EGR system, and performs the role of pilot injection. The engine induces the activation of the catalyst in the purification system (catalyst), which is limited in low temperature activation of the catalyst in the purification system (catalyst) due to the low temperature of the exhaust gas, thereby exhausting nitrogen oxide (NOx) and hydrocarbon (HC) series emissions. It suppresses the occurrence.

In the case of post-injection for activating the purification system as described above, a separate injection device (injector) or urea injection used in SCR is used, and the injection amount is determined according to the engine operating state and the catalyst temperature. In case of applying SCR for the injection, the cost burden of the installation is increased, and the complexity of the installation of the separate injection device has many problems in the practical application, and the determination of the injection amount after purification is not controlled, which leads to deterioration of fuel efficiency and The large amount of exhaust gas does not satisfy the exhaust gas regulation.

The present invention has been invented to solve the above problems, the object of which is to estimate the amount of exhaust gas according to the engine state in the diesel common rail injection system, calculate the required amount of after-injection, and then correct the fuel amount according to the activation of the catalyst By calculating the optimum after-injection fuel amount to control the post-injection duration, the exhaust gas is stabilized by stable catalyst activation and regeneration.

In addition, the present invention is intended to simplify the system and reduce the cost by performing the post-injection through the basic fuel injector.

1 is a configuration block diagram of the after injection fuel amount control device of the diesel common rail injection system according to the present invention.

Figure 2 is a flow chart for the after injection fuel amount control performance in the diesel common rail injection system according to the present invention.

The present invention for realizing the above object is an engine information detection means for detecting the general information necessary for engine control in the engine startup state; A control means for controlling the after-injection by analyzing the respective information of the detected engine to calculate the after-injection required fuel amount and considering the fuel pressure in the common rail; And injection means for injecting fuel of a post injection amount calculated by opening and closing for a predetermined time according to a control signal applied from the control means.

In addition, the present invention comprises the steps of determining the mass of the exhaust gas in the start-up state; Determining a post injection amount from the determined exhaust gas mass; It characterized in that it comprises a step of controlling the injection in accordance with the determined after injection amount.

The determination of the exhaust gas mass may include detecting a preset exhaust gas mass; It characterized in that it comprises a process of correction based on external variables such as cooling water temperature, atmospheric pressure.

The after injection amount may be determined by calculating a required amount of fuel per unit mass of exhaust gas with respect to an engine speed and a fuel amount to determine an after injection basic fuel amount; Cooling water temperature, characterized in that it comprises a process of correcting based on the parameters of the intake air amount.

When the correction of the cooling water temperature is not applied in the determination of the required amount of post-injection, the catalyst temperature is calculated according to the engine condition, and the correction according to the catalyst temperature is applied.

The post-injection duration may be determined in consideration of the pressure in the common rail to the determined post-injection demand amount.

The correction according to the catalyst temperature may be performed by analyzing the temperature sensor value through a set table when the catalyst diagnosis temperature sensor is mounted.

The correction according to the catalyst temperature may be corrected using the assumed catalyst temperature converted from the engine speed, the fuel amount, and the like, when there is no catalyst diagnostic temperature sensor.

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

As can be seen in Figure 1, the after injection amount control device of the diesel common rail injection system according to the present invention, the pressure detection unit 10, the engine speed detection unit 20, the cooling water temperature detection unit 30, the atmospheric pressure detection unit 40 , The catalyst temperature detector 50, the intake air amount detector 60, the controller 70, and the injector 80, the pressure detector 10 comprises a piezoelectric piezoelectric element and detects the pressure in the common rail to control the controller 70. ) As information for adjusting the fuel injection timing.

The engine speed detection unit 20 includes a magnetic pickup sensor as a crank position sensor, and detects the rotation speed of the crankshaft and provides information on the control unit 70.

The cooling water temperature detector 30 detects the temperature of the cooling water and provides the controller 70 to the controller 70 as information for correcting the increase or decrease of the fuel amount according to the water temperature.

The atmospheric pressure detection unit 40 detects the atmospheric pressure of the region to be driven from the air pressure information on the intake manifold inlet side and provides the controller 70 side as information for fuel amount correction.

The catalyst temperature detector 50 detects the temperature of the catalytic device activated by the exhaust gas and provides information about the catalyst device to the controller 70.

The intake air amount detector 60 measures the amount of air flowing into the intake manifold to calculate the amount of fuel, and provides information about the amount of air to the controller 70.

The controller 70 analyzes the detected information, calculates the fuel amount, adjusts the injection timing, estimates the amount of exhaust gas according to the engine state for activation and regeneration of the purification system (catalyst device), and calculates the amount of fuel. Estimates the required fuel quantity for the after injection, taking into account the cooling water temperature and atmospheric pressure, and calculates the required amount for the after injection by adding the fuel amount required for catalyst activation to the estimated value, and then considering the fuel pressure in the common rail. The injection duration is determined. The driving time of the injector 80 is controlled.

The injector 80 is opened and closed for a set time according to the control signal applied from the controller 70 to inject the amount of fuel calculated in each combustion chamber during pilot injection, main injection and post injection.

In the diesel common rail injection system according to the present invention including the functions as described above, the operations for pilot injection and main injection are the same or similar to those of the conventional operation, and thus the description of the operation is omitted and the post injection control is performed. The operation will be described with reference to FIG. 2 as follows.

In the diesel vehicle having a common rail injection system, main injection is performed in an optimal state according to engine state information such as pressure in the common rail detected by the control unit 70, engine speed, temperature of cooling water, atmospheric pressure, intake air amount, and the like. In order to activate or regenerate the purification system (catalyst) in the state, the controller 70 detects engine state information such as the pressure in the common rail, the engine speed, the temperature of the coolant, the atmospheric pressure, the amount of intake air and the like under the current conditions (S101). ).

Subsequently, the controller 70 analyzes the current engine speed and the fuel amount at the current engine condition detected through the set algorithm through the two-dimensional map table set through the engine test to extract the basic exhaust gas mass ( S102), the estimated mass of the exhaust gas is determined by calculation taking into account the correction value according to the temperature and atmospheric pressure of the cooling water to the extracted basic exhaust gas mass (S103).

When the estimated mass of the exhaust gas is determined as described above, the required fuel amount per unit mass of the exhaust gas is extracted through the two-dimensional map table in which the current engine speed and the fuel amount at the current engine condition are set through an engine test. The basic required fuel amount at the time of post injection is determined by calculating with the estimated mass of exhaust gas (S104).

When the basic required fuel amount at the time of post-injection is determined as described above, it is determined whether the temperature of the catalyst is detected from the catalyst sensor (S105).

In step S105, the catalyst sensor is mounted, and when the temperature is detected, the detected catalyst temperature is analyzed through the set table to perform correction according to the catalyst temperature (S107), and the catalyst temperature is not detected because the catalyst temperature sensor is not installed. If not, the catalyst temperature in the purification system (catalyst) is calculated according to engine conditions such as engine speed, fuel amount, etc., and the assumed catalyst temperature is detected (S106), and then corrected according to the assumed catalyst temperature (S107).

When the correction according to the catalyst temperature is applied in the above, the correction value for the current intake air amount is added to this value (S108) to extract the actual post injection demand amount (S109).

When the actual after-spray demand is calculated, the duration is determined in consideration of the pressure of the common rail (S110), and then the post-injection amount calculated through the drive control of the injector 80 is injected into the expansion stroke or the exhaust stroke of each combustion chamber. (S111).

As described above, in the diesel engine having the common rail injection system, the determination of the post-injection amount for activation or regeneration of the purification system (catalyst) is processed with a simple control logic without additional hardware, thereby providing reliability of the system. Post-injection is carried out without an injector to reduce production costs.

Claims (9)

Engine information detection means for detecting general information necessary for engine control while the engine is on; A control means for controlling the after-injection by analyzing the respective information of the detected engine to calculate the after-injection required fuel amount and considering the fuel pressure in the common rail; And an injection means for injecting fuel of a post injection amount, which is opened and closed for a predetermined time in accordance with a control signal applied from the control means. The method of claim 1, The engine information detecting means includes pressure detecting means for detecting a pressure in a common rail; Engine speed detection means for detecting engine speed; Water temperature detecting means for detecting a temperature of the cooling water; Atmospheric pressure detecting means for detecting an atmospheric pressure in an area in which the vehicle is operated; Catalyst temperature detection means for detecting the temperature of the catalyst activated by the exhaust gas; An after-injection amount control apparatus for a diesel common rail injection system comprising an air quantity detecting means for detecting an intake air amount. Determining a mass of the exhaust gas in the startup on state; Determining a post injection amount from the determined exhaust gas mass; And a step of controlling the injection according to the determined post injection amount. The method of claim 3, Determination of the exhaust gas mass may include detecting a preset exhaust gas mass; Post injection quantity control method of the diesel common rail injection system comprising the step of correcting based on external variables such as cooling water temperature, atmospheric pressure. The method of claim 3, The after injection amount may be determined by calculating a required amount of fuel per unit mass of exhaust gas with respect to an engine speed and a fuel amount to determine an after injection basic fuel amount; A method for controlling the after injection amount of the diesel common rail injection system, comprising the step of correcting the cooling water temperature and the intake air amount according to the variable. The method of claim 3, If the correction of the cooling water temperature is not applied in determining the after-injection demand amount, after the catalyst temperature according to the engine condition is calculated by applying a correction according to the catalyst temperature, the after injection amount control method of the diesel common rail injection system. The method of claim 3, The post-injection duration control method of the diesel common rail injection system, characterized in that the post injection injection duration is determined in consideration of the pressure in the common rail to the determined after-injection demand. The method of claim 6, Wherein the correction according to the catalyst temperature is the catalyst diagnostic temperature sensor is equipped with a post injection amount control method of the diesel common rail injection system, characterized in that for performing the correction by analyzing the temperature sensor value through a set table. The method of claim 6, The correction according to the catalyst temperature is corrected by using the assumed catalyst temperature converted from the engine speed, fuel amount, etc. when there is no catalyst diagnostic temperature sensor.