KR101272944B1 - System and method for regenerating soot of gasoline engine - Google Patents

Abstract

The present invention measures the pressure difference between the exhaust gas soot filter at the differential pressure sensor, and when the pressure difference is greater than the soot regeneration pressure, stops fuel supply to some or all of the cylinders of the gasoline engine, and bypass passages connected to the three-way valve. The present invention relates to a soot regeneration system and method for directly supplying exhaust gas to the soot filter through the present invention. There is an effect that can significantly reduce the smoke.

Description

SUIT REGENERATION SYSTEM AND METHOD FOR GASOLINE ENGINE {SYSTEM AND METHOD FOR REGENERATING SOOT OF GASOLINE ENGINE}

The present invention relates to a soot regeneration system and method for a gasoline engine, and more particularly, to a soot regeneration system and method for smoothing the soot regeneration by increasing the amount of oxygen exhausted to increase the reactivity with the soot. It is about.

In the future, global warming regulations are expected to be tightened. In particular, strong regulations will be applied to automobile exhaust, which is the main cause of CO2 emissions. To cope with this, the automotive industry is responding to global warming regulations in gasoline powertrain systems by minimizing air pollution by optimizing engine performance and minimizing air pollution by optimizing exhaust gas purification system.

Among the gasoline powertrain systems currently in development or in production, the technology to improve down-sizing and fuel efficiency of the engine is a gasoline direct injection engine (GDI engine). Compared with conventional port fuel injection, the GDI engine has the advantage of directly injecting fuel into the cylinder to increase thermal efficiency and volumetric efficiency.

However, in the case of a GDI engine, as the incomplete combustion section in the combustion chamber increases, particulate matter containing a soot (Particulate Matter, hereinafter referred to as PM) is a problem. As a result, Euro 6 regulations are scheduled for PM emission regulations and PM nano particle quantity for vehicles equipped with GDI engines.

In general, in the case of a conventional diesel engine, when the soot is accumulated, fuel is injected (post-injection) to the cylinder wall during exhaust stroke to reach the catalyst, generate heat of oxidation to raise the temperature of the exhaust gas to a high temperature, and discharge the soot by burning it. .

However, in the case of gasoline engines such as GDI engines, unlike the diesel engines, since they operate theoretical performance ratios, there is a problem that the oxygen in the exhaust is insufficient to reproduce the soot.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and provides a soot regeneration system and method for a gasoline engine that can improve the soot regeneration ability by supplying sufficient air containing oxygen even in a gasoline engine such as a GDI engine. It aims to do it.

As a means for solving the above problems, the embodiment of the present invention provides a soot regeneration system for a gasoline engine. In some embodiments, the soot regeneration system of the gasoline engine comprises a soot filter for removing exhaust fumes of the gasoline engine; A differential pressure sensor for measuring a pressure difference across the soot filter; An exhaust gas purification device installed between the gasoline engine and the particulate filter; A three-way valve disposed between the gasoline engine and the exhaust gas purification device and connected to a bypass passage for directly supplying exhaust gas to the particulate filter; And a control unit controlling the soot regeneration system, wherein the control unit stops the fuel supply to some or all of the cylinders of the gasoline engine when the pressure difference is greater than or equal to the soot regeneration pressure, and exhaust gas through the bypass passage. May be controlled to be supplied directly to the soot filter.

The control unit controls the exhaust gas to be directly supplied to the soot filter through the bypass passage when fuel supply is cut off to some or all of the cylinders of the gasoline engine even when the pressure difference is less than the soot regeneration pressure. It can be characterized.

The controller may determine the number of cylinders of the gasoline engine to cut off the fuel supply in consideration of at least one or more of an operating condition, a vehicle condition, a catalyst condition, and an amount of air required for the soot filter. .

The exhaust gas purification device may be a three-way catalyst.

When the gasoline engine is determined to be in the overrun section in stopping the fuel supply, the controller may stop the fuel supply only a part of the cylinders of the gasoline engine.

The control unit may resume the fuel supply to the cylinder in which the fuel supply is stopped when the pressure difference becomes the soot regeneration completion pressure.

The gasoline engine may be characterized in that the gasoline direct injection engine (Gasoline Direct Injection Engine, GDI engine).

Further, another embodiment of the present invention provides a soot regeneration method of a gasoline engine. In some embodiments, the soot regeneration method of the gasoline engine includes a first step of measuring a pressure difference across the exhaust gas particulate filter in a differential pressure sensor; Stopping the fuel supply to some or all of the cylinders of the gasoline engine when the pressure difference is greater than the soot regeneration pressure; And a third step of directly supplying the exhaust gas to the soot filter through a bypass passage connected to a three-way valve installed in front of the exhaust gas purification apparatus when fuel supply is cut off to a part or all of the gasoline engine. Can be.

In the second step, the number of cylinders of the gasoline engine to cut off the fuel supply may be determined in consideration of any one or more of driving conditions, vehicle conditions, catalyst conditions and the amount of air required for the soot filter. have.

The exhaust gas purification device may be a three-way catalyst.

When it is determined that the gasoline engine is in the overrun section in the second step, only a part of the cylinders of the gasoline engine may be stopped from supplying fuel.

The method may further include a fourth step of resuming the fuel supply of the cylinder in which the fuel supply is stopped when the pressure difference becomes the soot regeneration completion pressure.

The gasoline engine may be characterized in that the gasoline direct injection engine (Gasoline Direct Injection Engine, GDI engine).

According to the present invention, even in the case of a gasoline engine having a theoretical air-fuel ratio operation, since a sufficient amount of air can be supplied to the soot filter, the soot regeneration rate is increased and the soot regeneration temperature is reduced, thereby improving the soot regeneration ability of the soot filter.

In addition, in the case of the present invention, the soot filter can be safely protected by limiting the number of cylinders at which fuel supply is stopped under an overrun condition of the engine.

1 is a block diagram of a soot reproduction system according to an embodiment of the present invention.
2 is a flowchart of a soot reproducing method according to an embodiment of the present invention.
3 is a graph showing the oxygen concentration in the exhaust gas according to the number of cylinders of the engine is stopped fuel supply.

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

The soot regeneration system of the gasoline engine according to the embodiment of the present invention, as shown in FIG. 1, the soot filter 100 for removing the exhaust fumes of the engine 10, the engine 10, and the soot filter 100 A differential pressure sensor 200 for measuring a pressure difference between both ends, an exhaust gas purification device 300 installed between the engine 10 and the particulate filter 100, and the engine 10 and exhaust gas purification device. It includes a bypass passage 400 provided between the 300, the three-way valve 500 and the control unit 600 for controlling the soot regeneration system.

The control unit 600 stops the fuel supply to some or all of the cylinders of the gasoline engine 10 when the pressure difference is greater than or equal to the soot regeneration pressure, and the exhaust gas directly passes through the bypass passage 400. 100) characterized in that the control to be supplied.

The engine 10 to which the embodiment of the present invention is applied may generate particulate matter including soot in the gasoline engine according to an increase in the incomplete combustion section in the combustion chamber. It can be a gasoline direct injection engine (GDI engine).

The soot filter 100 is a filter for filtering harmful particulate matter (PM) such as soot contained in the exhaust gas of the engine 10, and an exhaust pipe for exhausting exhaust gas of an automobile. It is installed on the back. In particular, in the present invention, the soot filter for collecting PM contained in the exhaust gas of the gasoline engine is also called a gasoline particulate filter (GPF).

The majority of PM is a hydrocarbon called soot, which is generated when fuel is not burned properly. The soot filter 100 collects PM containing such a soot using a catalytic filter. The catalyst is formed in the shape of a honeycomb and subjected to a special coating to adsorb the soot.

In the case of the soot filter 100, when the collected PM reaches a predetermined level, the particulate filter 100 undergoes a regeneration process to remove it through post injection. The regeneration process is a process of injecting fuel into the high-temperature exhaust gas in the exhaust stroke of the engine 10 to generate additional combustion to further increase the temperature to activate the catalyst to oxidize the remaining PM to ash.

The differential pressure sensor 200 serves to measure the pressure difference between both ends of the soot filter 100, and is disposed at the front end P1 and the rear end P2 of the soot filter 100 as shown in FIG. 1. The pressure difference (P1-P2) at both ends is measured by sensing the pressure of the exhaust gas flowing into the 100 and the pressure of the exhaust gas flowing out through the soot filter 100. The differential pressure sensor 200 is connected to the control unit 600 and transmits information on the measured pressure difference to the control unit 600. That is, the more the PM is collected in the catalyst inside the soot filter 100, the more the air flow is blocked and the value of the pressure difference (P1-P2) at both ends of the soot filter 100 increases, and the differential pressure sensor 200 measures this. Transfer to the control unit 600.

The exhaust gas purification device 300 is installed between the gasoline engine 10 and the soot filter 100 to clean the harmful substances contained in the exhaust gas into harmless substances. As an example of such an exhaust gas purification device 300, a three way catalyst (TWC) device may be used as illustrated in FIG. 1.

The three-way catalyst 300 is a device that converts three harmful substances (CO, HC, NO _X ) into a harmless gas, and is generally chemically combined using a platinum catalyst and chemically combined using a rhodium catalyst. The reduction process lowers the level of harmful substances and converts them into harmless gases. With such a process, it is converted into carbon monoxide (CO) and hydrocarbons (HC) is carbon dioxide (CO ₂₎ and water (H ₂ O) harmless by oxidation in combination with a coral (O ₂₎ contained in the exhaust gas, the NO _X Is converted to nitrogen (N ₂ ) and oxygen (O ₂ ).

In the case of the three-way catalyst 300, since the ratio of air and fuel has the highest efficiency near the theoretical air-fuel ratio, in general, in the case of gasoline engine cars, the theoretical air-fuel ratio may be obtained by using an oxygen sensor and an ECU (Electronic Control Unit) ECU, etc. To control.

On the other hand, in the case of the soot filter 100, as described above, if the PM is continuously collected and satisfies a predetermined condition, the particulate filter 100 undergoes a regeneration process of oxidizing and removing the same at a high temperature. For this regeneration process, a large amount of air is required. When the theoretical air-fuel ratio operation is performed as described above, the amount of oxygen is limited, and thus a problem in that it is impossible to sufficiently supply oxygen for regeneration of the soot filter 100 occurs.

In order to solve this problem, in the case of the present invention, a three-way valve 500 is installed between the engine 10 and the exhaust gas purifying apparatus 300, as shown in the embodiment of FIG. A pass passage 400 is formed so that the exhaust gas of the engine 10 can be directly supplied to the particulate filter 100 without passing through the three-way catalyst 300, and the control unit 600 controls the differential pressure sensor 200. In the case where the pressure difference (P1-P2) at both ends of the soot filter 100 measured in the above is greater than a preset soot regeneration pressure, the fuel supply to some or all of the cylinders of the gasoline engine 10 is stopped, and the three-way valve By controlling the 500, the exhaust gas is directly supplied to the soot filter 100 through the bypass passage 400 so that sufficient oxygen is supplied to the soot filter 100.

The control unit 600 may be an ECU (Electronic Control Unit) as a part of controlling the soot regeneration system of the gasoline engine as a whole.

The control unit 600 is a part of the cylinder of the gasoline engine 10 or even when the pressure difference (P1-P2) across the smoke filter 100 measured by the differential pressure sensor 200 is less than the predetermined soot regeneration pressure When all of the fuel supply is cut off, the exhaust gas may be controlled to be directly supplied to the particulate filter 100 through the bypass passage 400. This means that even if the pressure difference between the soot filter 100 does not reach the soot regeneration pressure, the fuel supply to the engine 10 may be cut off at a deceleration section of a predetermined rotation speed (rpm) or the like. This is because the soot filter 100 can be regenerated by supplying oxygen directly to the soot filter 100 without passing the gas through the three-way valve 500.

The control unit 600 stops the fuel supply in consideration of any one or more of the operating conditions of the gasoline engine, vehicle conditions, catalyst conditions and the amount of air required for the soot filter in stopping the fuel supply of the gasoline engine cylinder The number can be determined. For example, in the case of the four-cylinder engine and the six-cylinder engine, since the amount of air required for the soot filter 100 may be different from each other, the soot filter 100 may be optimally changed by changing the number of idle cylinders at which fuel supply is blocked. Can be played back.

Meanwhile, in determining the number of idle cylinders at which the fuel supply is cut off in the controller 600, the fuel supply may be cut off in all cylinders. However, when the engine 10 enters the overrun condition in the filter regeneration process, the engine ( It is possible to set the fuel supply to only some cylinders without stopping the fuel supply to all the cylinders of 10).

When the car enters the overrun state, the air is supplied to the soot filter 100 more than usual. At this time, if all the cylinders are stopped and the air is supplied too much, the exhaust gas temperature is too high in some cases. This is to prevent such a phenomenon because an abnormal combustion phenomenon in which 100) may be broken may occur.

In particular, if the smoke in the filter is ignited in the situation where the car climbs the hill and overrun after the hill, air is excessively supplied to the ignited filter and the temperature in the filter is rapidly increased, which may cause the smoke filter 100 to be damaged. However, by stopping the fuel supply to only some cylinders as described above, this problem can be prevented in advance.

When the soot regeneration is completed, that is, when the pressure difference (P1-P2) at both ends of the soot filter 100 reaches the preset soot regeneration completion pressure, the control unit 600 resumes the fuel supply to the rest cylinder to resume normal operation. To be converted. When the soot is removed through the regeneration process, the pressure difference (P1-P2) at both ends of the soot filter 100 becomes smaller and smaller, and becomes less than the set soot regeneration completion pressure.

Hereinafter, a soot regeneration method of a gasoline engine according to an embodiment of the present invention will be described.

In the soot regeneration method of the gasoline engine according to the embodiment of the present invention, as shown in FIG. 2, a first step (S10) of measuring the pressure difference between the both ends of the soot filter 100 is large, and the pressure difference is greater than or equal to the soot regeneration pressure. In the case of the second step (S20) for stopping the fuel supply to some or all of the cylinder of the gasoline engine 10, and the three-way valve 500 installed in front of the exhaust gas purification device 300 when the fuel supply is cut off The third step (S30) for directly supplying the exhaust gas to the soot filter 100 through the bypass passage 400 connected to the (S), and when the regeneration of the soot filter 100 is completed, the fuel supply of the cylinder in which the fuel supply is stopped It characterized in that it comprises a fourth step (S40) to resume.

The engine 10 to which the embodiment of the present invention is applied may be a gasoline direct injection engine (Gasoline Direct Injection Engine, GDI engine) in which a lot of PM is generated among the gasoline engine, and the soot filter 100 is a gasoline soot filter 100. (GPF 100).

The first step is a step (S10) of measuring the pressure difference across the exhaust gas particulate filter (GPF) 100 at the differential pressure sensor 200 (S10), the differential pressure sensor 200 is installed in the particulate filter 100 In the exhaust filter 100 senses the exhaust gas pressure of the front end and the exhaust gas pressure of the rear end by measuring the pressure difference and transmits the information on the measured pressure difference to the controller 600. The controller 600 may be an electronic control unit (ECU).

The controller 600 determines whether the pressure difference transmitted from the differential pressure sensor 200 is equal to or greater than the preset soot regeneration pressure (S11), and when the pressure is greater than the soot regeneration pressure, supplying fuel to some or all of the cylinders of the engine 10. Stop.

In this case, the controller 600 determines the number of idle cylinders in consideration of one or more of the amount of air required for the gas filter 100, the operating condition, the vehicle condition, the catalyst condition and the soot filter 100 as well as the pressure difference information. (S12).

In addition, when setting the number of idle cylinders in the control unit 600, if the engine 10 enters the overrun condition after the regeneration of the soot filter 100, the controller 600 does not stop the entire cylinder, but sets to pause only a portion of the cylinders. It is desirable to.

The second step is to stop the fuel supply to the cylinder of the engine 10 in accordance with the determined number of idle cylinders to stop the engine 10 (S20). In this way, when the fuel supply to the part or all of the engine 10 is stopped, air is supplied through the rest cylinder to increase the oxygen concentration in the exhaust gas.

The third step corresponds to a case where the pressure difference between the soot filter 100 and the soot regeneration pressure is greater than or equal to the soot regeneration pressure (S20). When the fuel supply to the gasoline engine 10 is cut off due to other reasons, the control unit 600 controls the three-way valve 500 installed in front of the exhaust gas purifier 300 in other cases. The exhaust gas is directly supplied to the particulate filter 100 through the bypass passage 400 (S30).

When the exhaust gas containing a large amount of oxygen is directly supplied to the soot filter 100 through this process, regeneration of the soot filter 100 is started (S31).

Even during regeneration, the number of idle cylinders can be changed and controlled according to the operating conditions of the engine 10 or the amount of air required for the particulate filter 100 (S32). In particular, when the engine 10 enters the overrun condition during regeneration of the GPF 100 (S33), as described above, only a part of the cylinders of the engine 10 are kept in a state of rest and the engine 10 is rested. Control not to (S34).

The fourth step is to switch back to the normal operation mode when the soot reproduction is completed (S40). That is, when the pressure difference between the soot filter 100 reaches the soot free pressure (soot regeneration completion pressure) through the above process, the fuel supply to the idle cylinder is resumed to switch to normal operation. The soot regeneration completion pressure is a preset value. When the soot is removed through the regeneration process, when the pressure difference between the both ends of the soot filter 100 becomes smaller and smaller than the set value, the regeneration is stopped and the operation is switched to normal operation.

3 is a graph showing the oxygen concentration in the exhaust gas according to the number of idle cylinders of the engine. FIG. 3 shows the case of a four-cylinder engine, in which the portion shown by 1% in FIG. 3 represents the oxygen concentration in the exhaust gas of the cylinder in which the fuel is being supplied, and the portion shown by 21% is stopped when the fuel supply is stopped. As a cylinder, the oxygen concentration of air is shown.

As shown in FIG. 3, in arithmetic operation of the four-cylinder engine, when all four cylinders are operated, the concentration of oxygen in the exhaust gas is about 4%, the sum of the four cylinders is about 1%. In this case, the oxygen concentration in the general atmosphere without fuel mixture is added to 21%, so the sum of oxygen concentrations in the four cylinders is 24%, and the oxygen concentration in the exhaust gas rises to 6%. At the sum of the oxygen concentrations at 44%, the oxygen concentration in the exhaust gas is increased to 11%. Likewise, when the three cylinders are stopped, the oxygen concentration in the exhaust gas is increased to 16%.

Experimental data show that if the oxygen concentration in the exhaust gas rises from 0.5% to 10% at the same temperature, the soot oxidation rate is about 5 times faster, and the oxygen concentration in the exhaust gas is 1 based on the same regeneration time (20 minutes). Increasing from 10% to 10% reduces the temperature required for soot oxidation from approximately 710 ° C to 650 ° C. Therefore, according to the soot regeneration system and method of the gasoline engine according to the embodiment of the present invention, the soot can be quickly regenerated at a low temperature.

10: engine 100: particulate filter (GPF)
200: differential pressure sensor 300: exhaust gas purification device (three-way catalyst)
400: bypass passage 500: three-way valve
600: control unit (ECU)

Claims (13)

In the soot regeneration system of a gasoline engine,
A soot filter for removing exhaust gas soot of the gasoline engine;
A differential pressure sensor for measuring a pressure difference across the soot filter;
An exhaust gas purification device installed between the gasoline engine and the particulate filter;
A three-way valve disposed between the gasoline engine and the exhaust gas purification device and connected to a bypass passage for directly supplying exhaust gas to the particulate filter; And
A control unit for controlling the soot reproducing system;
The control unit stops the fuel supply to some or all of the cylinders of the gasoline engine when the pressure difference is greater than the soot regeneration pressure, so that the exhaust gas is supplied directly to the soot filter through the bypass passage,
Even when the pressure difference is less than the soot regeneration pressure, when fuel supply is cut off to some or all of the cylinders of the gasoline engine, exhaust gas is supplied directly to the soot filter through the bypass passage,
When it is determined that the gasoline engine is in an overrun section in stopping the fuel supply, only a part of the cylinders of the gasoline engine stops the fuel supply.
The gasoline engine is a gasoline direct injection engine (Gasoline Direct Injection Engine, GDI engine), characterized in that the soot regeneration system of the gasoline engine. delete The method of claim 1,
The control unit determines the number of cylinders of the gasoline engine to cut off the fuel supply in consideration of at least one or more of the operating conditions, vehicle conditions, catalyst conditions and the amount of air required for the soot filter of the gasoline engine. Suit playback system. The method of claim 1,
The exhaust gas purification device is a soot regeneration system of a gasoline engine, characterized in that the three-way catalyst. delete The method of claim 1,
And the control unit resumes the fuel supply of the cylinder in which the fuel supply is stopped when the pressure difference becomes the soot regeneration completion pressure. delete In the soot regeneration method of a gasoline engine,
A first step of measuring a pressure difference across the exhaust gas particulate filter in the differential pressure sensor;
Stopping the fuel supply to some or all of the cylinders of the gasoline engine when the pressure difference is greater than the soot regeneration pressure; And
And a third step of directly supplying exhaust gas to the soot filter through a bypass passage connected to a three-way valve installed in front of the exhaust gas purifying apparatus when the fuel supply to the gasoline engine is cut off in part or all.
When it is determined that the gasoline engine is in the overrun section in the second step, only a part of the cylinders of the gasoline engine stops fuel supply.
The gasoline engine is a gasoline direct injection engine (Gasoline Direct Injection Engine, GDI engine), characterized in that the soot regeneration method of the gasoline engine. 9. The method of claim 8,
Gasoline characterized in that the number of cylinders of the gasoline engine to cut off the fuel supply is determined in consideration of at least one or more of the operating conditions, vehicle conditions, catalyst conditions and the amount of air required for the soot filter in the second step How to play the suit of the engine. 9. The method of claim 8,
The exhaust gas purifying apparatus is a soot regeneration method of a gasoline engine, characterized in that the three-way catalyst. delete 9. The method of claim 8,
The method
And a fourth step of resuming the fuel supply to the cylinder in which the fuel supply is stopped when the pressure difference reaches the soot regeneration completion pressure. delete

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