KR101655192B1 - Engine having low pressure exhaust gas recirculation system - Google Patents

Abstract

According to the engine having the low-pressure easy system according to the embodiment of the present invention, the intake line arranged to suck ambient air, the low-pressure engine which recirculates the exhaust gas from the downstream side of the catalytic unit of the exhaust line to the intake line, An electric supercharger arranged to mix the exhaust gas with the outside air to selectively compress the mixed gas, a mixed gas branched from the intake line downstream of the electric supercharger and compressed by the electric supercharger A pressure sensor for sensing the pressure of the above-mentioned easy-to-tank, a tank for selectively connecting said intake line and said easy-to-tank, said pressure sensor being disposed on a connection line connecting said intake line to said easy- A valve, and a downstream side of a point branched from the intake line to the above-mentioned easy tank It may include a throttle valve that controls the gas supplied to the chamber.

Description

[0001] ENGINE HAVING LOW PRESSURE EXHAUST GAS RECIRCULATION SYSTEM [0002]

The present invention relates to a system and a method for controlling an exhaust gas recirculation system having a low pressure inert gas system for rapidly controlling recirculated exhaust gases remaining in an intake line at tip out in an easy gas usage mode using recirculated exhaust gas to improve combustion stability and reactivity of the engine Engine.

Generally, in most diesel engines and some gasoline engines mounted on vehicles, an exhaust gas recirculation system is installed to cope with exhaust gas regulations.

Such an exhaust gas recirculation system reduces the combustion temperature of the engine, reduces the amount of generated nitrogen oxides (NOx), and reduces fuel consumption by returning a part of the exhaust gas discharged from the engine to the intake apparatus of the cylinder.

In the low-pressure EGR apparatus, the exhaust gas formed at the downstream of the particulate filter is cooled by the EGR cooler and then recirculated. Therefore, the EGR gas flow path is long compared with the conventional high-pressure EGR apparatus, and since it is low in pressure, it is not stable in response and controllability.

And, in an engine using low pressure exhaust gas recirculation (LP EGR) technology, while using recirculated exhaust gas at a set ratio (for example, 10% to 20%) with respect to intake air, The recirculated exhaust gas remains between the throttle valve and the idle valve when the throttle valve is closed.

Therefore, the recirculated exhaust gas remaining in the intake line increases the combustion instability and may cause a response delay in re-acceleration.

It is an object of the present invention to provide a combustion control method and system that can quickly remove recirculated exhaust gas remaining in an intake line at a tip-out condition during recycling exhaust gas is being used in an engine to increase combustion instability and rapidly supply external air to a combustion chamber And to provide an engine having a low-pressure easy-to-operate system capable of improving the performance.

According to the engine having the low-pressure easy system according to the embodiment of the present invention, the intake line arranged to suck ambient air, the low-pressure engine which recirculates the exhaust gas from the downstream side of the catalytic unit of the exhaust line to the intake line, An electric supercharger arranged to mix the exhaust gas with the outside air to selectively compress the mixed gas, a mixed gas branched from the intake line downstream of the electric supercharger and compressed by the electric supercharger A pressure sensor for sensing the pressure of the above-mentioned easy-to-tank, a tank for selectively connecting said intake line and said easy-to-tank, said pressure sensor being disposed on a connection line connecting said intake line to said easy- A valve, and a downstream side of a point branched from the intake line to the above-mentioned easy tank It may include a throttle valve that controls the gas supplied to the chamber.

A low-pressure idle valve for controlling the flow rate of the azeotrope gas is disposed at a point where the azeelain and the intake line join, and a control valve for controlling the intake air is disposed upstream of the low-pressure idle valve in the intake line , And an air cleaner may be disposed on the upstream side of the control valve.

A low-pressure idle valve for controlling the flow rate of the azeotrope gas is disposed at a point where the azeelain and the intake line are merged. An exhaust gas passing through the exhaust line passes through the intake line downstream of the low- A compressor of a turbocharger that rotates and compresses gas flowing through the intake line may be disposed.

An intercooler is disposed downstream of the turbocharger in the intake line to cool the compressed gas, and the electric supercharger may be disposed downstream of the intercooler.

A bypass line for bypassing the electric supercharger is formed in the intake line, and a bypass valve for controlling gas passing through the bypass line may be disposed in the bypass line.

The bypass line may be joined to a point where the intake line and the idle tank are connected.

A turbine of the turbocharger is disposed in the exhaust line, a first catalyst unit for processing exhaust gas is disposed downstream of the turbine, and the alline is branched on the downstream side of the first catalyst unit .

The low pressure allignal may be arranged with a low pressure alcohole to cool the recycle exhaust gas.

And a second catalyst unit for treating the exhaust gas may be disposed downstream of the branch point of the alline in the exhaust line.

And a controller for controlling the tank valve, the electric supercharger, the bypass valve, the idle valve, and the control valve based on a driving condition including a pressure of the idle tank sensed by the pressure sensor .

According to the present invention for achieving such a purpose, in the use mode in which the exhaust gas is recirculated, when the exhaust gas is switched to the non-use mode in which the exhaust gas is not recirculated, the recycle exhaust gas remaining in the intake line is quickly collected and removed, It is possible to improve the combustion stability and to improve the responsiveness upon re-acceleration.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic diagram showing a state in which an isotonic gas is trapped in an engine having a low-pressure easy system according to an embodiment of the present invention; FIG.
FIG. 2 is a schematic diagram showing a state in which an isotonic gas is collected in an engine having a low-pressure easy system according to an embodiment of the present invention.
FIG. 3 is a schematic diagram showing a state in which an isotonic gas trapped in an engine having a low-pressure easy system according to an embodiment of the present invention is reused.
4 is a flowchart illustrating a method of controlling an engine having a low-pressure easy system according to an embodiment of the present invention.

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

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic diagram showing a state in which an isotonic gas is trapped in an engine having a low-pressure easy system according to an embodiment of the present invention; FIG.

1, an engine having a low pressure easy system includes an intake line 110, an intake manifold 180, an engine block 185, an exhaust manifold 190, an exhaust line 195, (199).

The air cleaner 100, the control valve 115, the compressor 130 of the turbocharger 135, the intercooler 145, the electric supercharger 150 and the throttle valve 160 are sequentially connected to the intake line 110 And a bypass valve 155 is installed on the bypass line bypassing the electric supercharger 150. [

The turbine 125 of the turbocharger 135, the first catalytic unit 197 and the second catalytic unit 200 are sequentially arranged in the exhaust line 195, and the low- Is branched at the exhaust line 195 between the first catalytic unit 197 and the second catalytic unit 200 and merged into the intake line 110 between the compressor 130 and the air cleaner 100 .

A low-pressure idler valve 140 and a low-pressure relief valve 120 are sequentially disposed in the low-pressure isolator 199. The low-pressure relief valve 120 is connected to the low- Are located at the point where line 110 meets.

In the embodiment of the present invention, a connection line 177 is branched on the downstream side of the electric supercharger 150 and on the downstream side of the bypass valve 155, and the connection line 177 is branched And is connected to the al tank 165. The tank valve 175 is disposed in the connection line 177 and the pressure sensor 170 is disposed to sense the pressure of the inert gas tank 165.

The control valve 115 is disposed on the upstream side of the point where the low-pressure isolating line 199 meets the intake line 110 and is connected to the low-pressure isolator 199 To control the flow of the recirculated exhaust gas and to control the flow of the outside air.

The recirculated exhaust gas flows from the exhaust line 195 to the intake line 110 through the low pressure isolator 199 and the low pressure idler cooler 140 cools the recirculated exhaust gas, (120) controls the flow of recirculated exhaust gas.

The turbine 125 of the turbocharger 135 is rotated by the exhaust gas to rotate the compressor 130. The compressor 130 compresses the gas flowing through the intake line 110, (145) cools the compressed hot gas.

The electric supercharger 150 recompresses the gas passing through the intercooler 145 and supplies the gas to the combustion chamber of the engine block 185 through the intake manifold 180. The turbine 125 is operated by the exhaust gas discharged from the exhaust manifold 190 to rotate the compressor 130 and the first and second catalyst units 197 and 200 are connected to exhaust gas Thereby reducing the harmful substances contained in the exhaust gas.

In an embodiment of the present invention, in the recirculated exhaust gas feed mode, recirculated exhaust gas is fed to the intake line 110 via the low pressure all-air line 199, and in the recirculated exhaust gas stop mode, (120) is closed.

Here, the recycle exhaust gas stop mode may include a tip-out condition, and the tip-out means a condition in which the accelerator pedal is not operated in a state where the driver removes the foot from the accelerator pedal. Therefore, the throttle valve 160 can be closed under the tip-out condition.

Meanwhile, even if the low-pressure relief valve 120 is closed, the recycle exhaust gas filled between the compressor 130 and the throttle valve 160 is supplied to the set time combustion chamber, making it difficult to quickly control the operating conditions of the engine.

Accordingly, in the embodiment of the present invention, the control unit 250 opens the tank valve 175 disposed in the connection line 177, operates the electric supercharger 150, Is collected in the tank 165.

At this time, the control unit 250 closes the bypass valve 155 bypassing the electric supercharger 150, closes the idle valve 120, and the control valve 115 opens. In addition, the gas supplied to the combustion chamber of the engine block 185 is controlled by the throttle valve 160.

The control unit 250 may be implemented by one or more microprocessors operating according to a set program, and the set program may include a series of instructions for performing a method according to an embodiment of the present invention to be described later.

FIG. 2 is a schematic diagram showing a state in which an isotonic gas is collected in an engine having a low-pressure easy system according to an embodiment of the present invention. In Fig. 2, the same or similar parts as those in Fig. 1 are not described, and the differences will be mainly described.

When it is determined that the collection of the recirculated exhaust gas is completed through the pressure sensor 170 of the idle tank 165, the tank valve 175 is closed and the electric supercharger 150 is turned off.

The electric supercharger 150 can be operated according to the driving conditions and the bypass valve 155, the low-pressure relief valve 120, the control valve 115, and the throttle valve 160, Can also be variably controlled.

FIG. 3 is a schematic diagram showing a state in which an isotonic gas trapped in an engine having a low-pressure easy system according to an embodiment of the present invention is reused.

In Fig. 3, the same or similar parts as those in Fig. 1 and Fig. 2 are not described, and differences will be mainly described.

In accordance with the operating conditions, the tank valve 175 is opened to use the collected recycled exhaust gas. The condition for opening the tank valve 175 to reuse the recirculated exhaust gas may include a condition for the driver's foot to operate the accelerator pedal in tip-in condition.

That is, in the tip-out condition, the inert gas can be collected in the inert gas tank 165, and the recirculated exhaust gas collected in the inert gas tank 165 under the condition of being tip can be reused.

The electric supercharger 150 may be operated according to the driving conditions and the bypass valve 155, the low-pressure relief valve 120, the control valve 115, and the throttle valve 160 may be actuated, Can also be variably controlled.

4 is a flowchart illustrating a method of controlling an engine having a low-pressure easy system according to an embodiment of the present invention.

Referring to FIG. 4, in S400, the exhaust gas is recirculated through the low pressure alleline, and it is determined in S410 whether a tip-out condition is satisfied.

The tip-out condition means that the driver stops the operation of the accelerator pedal by removing the foot from the accelerator pedal, and the controller 250 can determine the tip-out condition and the tip-in condition through the operation signal of the accelerator pedal.

At S420, the tank valve 175 is opened. Here, the throttle valve 160 may be closed, the bypass valve 155 may be closed, the idle valve 120 may be closed, and the control valve 115 may be opened.

Then, in S430, the electric supercharger 150 is operated to effectively collect the recirculated exhaust gas filled between the throttle valve 160 and the compressor 130.

If it is determined in S440 that the recirculated exhaust gas is collected through the pressure sensor 170 of the idle tank 165, the tank valve 175 is closed in S450.

In step S460, a tip in condition is determined. This tip-on condition may include a condition that the accelerator pedal is reactivated, and a recirculated exhaust-gas free generator may be supplied to the combustion chamber.

If the condition that the recirculated exhaust gas is supplied to the combustion chamber is satisfied in accordance with the driving condition, the opening rate of the tank valve 175 is controlled in step S470 so that the recirculated exhaust gas captured in the easy- Can be discharged to the intake line 110 and used in the combustion chamber.

While the present invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, And all changes to the scope that are deemed to be valid.

100: Air cleaner 110: Intake line
115: control valve 120: low-pressure easy-to-open valve
125: Turbine 130: Compressor
135: Turbo Charger 140: Low Pressure, Al Cooler
145: Intercooler 150: Super Charger
155: bypass valve 160: throttle valve
165: Easy Tank 170: Pressure sensor
175: tank valve 177: connection line
180: intake manifold 185: engine block
190: exhaust manifold 195: exhaust line
197: first catalyst unit 200: second catalyst unit
250: control unit 199: low pressure,

Claims (10)

An intake line arranged to suck ambient air;
A low pressure air line for recirculating the exhaust gas to the intake line at the downstream side of the catalyst unit of the exhaust line;
An electric supercharger arranged to mix the recirculated exhaust gas and the ambient air and to selectively compress the mixed gas;
An idle tank branched from the intake line on the downstream side of the electric supercharger and arranged to store a mixed gas compressed by the electric supercharger;
A pressure sensor for sensing a pressure of the easy tank;
A tank valve disposed in a connection line connected from the intake line to the idle tank for selectively connecting the intake line and the idle tank; And
A throttle valve for controlling a gas supplied to a combustion chamber disposed at a downstream side of a point branched from the intake line to the idle tank;
Gt; a < / RTI > low-pressure easy system. The method of claim 1,
A low-pressure inlet valve for controlling the flow rate of the azeotrope gas is disposed at a point where the azeelain and the intake line join,
And an air cleaner is disposed upstream of the control valve for controlling the intake air on an upstream side of the low pressure intake valve in the intake line. The method of claim 1,
A low-pressure inlet valve for controlling the flow rate of the azeotrope gas is disposed at a point where the azeelain and the intake line join,
And a compressor of a turbocharger which is rotated by the exhaust gas passing through the exhaust line and compresses the gas flowing through the intake line is disposed on the downstream side of the low pressure intake valve in the intake line. An engine with an egg system. 4. The method of claim 3,
An intercooler is disposed downstream of the turbocharger in the intake line to cool the compressed gas,
Characterized in that the electric supercharger is disposed on the downstream side of the intercooler. 3. The method of claim 2,
A bypass line for bypassing the electric supercharger is formed in the intake line,
Wherein the bypass line is provided with a bypass valve for controlling the gas passing through the bypass line. The method of claim 5,
Wherein the bypass line is joined to a point where the intake line and the idle tank are connected to each other. 4. The method of claim 3,
A turbine of the turbocharger is disposed in the exhaust line,
A first catalyst unit for treating exhaust gas is disposed on the downstream side of the turbine,
And a low-pressure injection system in which the all-air diverges at a downstream side of the first catalytic unit. The method of claim 1,
Characterized in that the low pressure allignal is arranged with a low-pressure off-cooler to cool the recirculated exhaust gas. The method of claim 1,
And a second catalyst unit for treating the exhaust gas is disposed downstream of the branch point of the alline in the exhaust line. The method of claim 5,
Based on a driving condition including a pressure of the inert gas tank sensed by the pressure sensor,
A controller for controlling the tank valve, the electric supercharger, the bypass valve, the idle valve, and the control valve;
Gt; a < / RTI > low-pressure easy system.

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