Engine having low pressure EGR system and control method thereof

Patent metadata

Field	Value
Publication number	US-9726090-B2
Application number	US-201514943940-A
Country	US
Kind code	B2
Filing date	Nov 17, 2015
Priority date	May 7, 2015
Publication date	Aug 8, 2017
Grant date	Aug 8, 2017

Abstract

An engine having a low pressure EGR system includes: an intake line suctioning outdoor air and transferring the outdoor air to a combustion chamber; a turbocharger actuated by exhaust gas which flows in an exhaust line to compress gas which flows in the intake line; a supercharger installed at a downstream side of the turbocharger; a low pressure EGR line branched at one side of the exhaust line and joined to an upstream side of the turbocharger to recirculate the exhaust gas; a recirculation line branched on the intake line at a downstream side of the supercharger and joined to the intake line at an upstream side of a point where the low EGR line and the intake line meet; and a control unit controlling the actuation of the supercharger. The control unit actuates the supercharger in the case of a coasting driving condition.

First claim

What is claimed is:

1. An engine including a low pressure EGR system, comprising:
an intake line configured to suction an outdoor air and transfer the outdoor air to a combustion chamber;
a turbocharger actuated by an exhaust gas which flows in an exhaust line and configured to compress gas which flows in an intake line;
a supercharger installed at a downstream side of the turbocharger;
a low pressure EGR line branched at one side of the exhaust line and joined to an upstream side of the turbocharger from the intake line to recirculate the exhaust gas;
a recirculation line branched on the intake line at a downstream side of the supercharger and joined to the intake line at an upstream side of a point where the low pressure EGR line and the intake line meet; and
a control unit configured to control an actuation of the supercharger,
wherein the control unit is configured to actuate the supercharger under a coasting driving condition.

2. The engine of claim 1 , further comprising:
a first catalyst unit disposed on the exhaust line to reduce an amount of a harmful substance included in the exhaust gas,
wherein the low pressure EGR line is branched at a downstream side of the first catalyst unit to be connected to the intake line.

3. The engine of claim 2 , further comprising:
a second catalyst unit installed at a downstream side of the first catalyst unit and configured to reduce the harmful substance included in the exhaust gas,
wherein the low pressure EGR line is branched from the exhaust line between the first catalyst unit and the second catalyst unit.

4. The engine of claim 1 , further comprising:
a control valve disposed between the point where the low pressure EGR line and the intake line meet and a point where the recirculation line and the intake line meet and controlling a flow of supplied gas.

5. The engine of claim 4 , wherein an air cleaner configured to filter foreign substances included in outdoor air is disposed at an upstream side of the intake line, and the recirculation line joins in the intake line between the control valve and the air cleaner.

6. The engine of claim 1 , wherein the low pressure EGR line comprises
a low pressure EGR cooler configured to cool the recirculated exhaust gas; and
a low pressure EGR valve configured to control a flow of the recirculated exhaust gas.

7. The engine of claim 1 , further comprising an intercooler disposed between the turbocharger and the supercharger, the intercooler configured to cool the gas compressed by the turbocharger.

8. The engine of claim 1 , further comprising a bypass line bypassing the supercharger and a bypass valve installed on the bypass line.

9. The engine of claim 1 , further comprising a recirculation valve configured to control a recirculated gas on the recirculation line,
wherein the control unit is configured to open the recirculation valve to circulate a mixed gas when the coasting driving condition is reached.

10. The engine of claim 9 , wherein the recirculation valve is installed at a point where the recirculation line is branched from the intake line.

11. The engine of claim 1 , wherein a throttle valve configured to control a gas supplied to the combustion chamber is disposed at a downstream side of the point where the intake line and the recirculation line are branched.

12. A control method of an engine, the engine including:
an intake line configured to suction an outdoor air and transfer the outdoor air to a combustion chamber;
a turbocharger actuated by an exhaust gas which flows in an exhaust line and configured to compress gas which flows in the intake line;
a supercharger installed at a downstream side of the turbocharger;
a low pressure EGR line branched at one side of the exhaust line and joined to an upstream side of the turbocharger to recirculate the exhaust gas;
a recirculation line branched on the intake line at a downstream side of the supercharger and joined to the intake line at an upstream side of a point where the low EGR line and the intake line meet;
a throttle valve;
a vehicle speed sensor;
an accelerator pedal sensor disposed in rear of the supercharger; and
a control unit configured to control operations of the supercharger, the throttle valve, the low pressure EGR valve, and a recirculation valve by receiving output signals of the throttle valve and the vehicle speed sensor,
the method comprising:
determining by the control unit whether a coasting driving condition is reached according to the signals of the throttle valve and the vehicle speed sensor; and
controlling by the control unit the throttle valve to be closed, the recirculation valve to be opened, and the turbocharger to be actuated when the coasting driving condition is reached.

13. The method of claim 12 , wherein the recirculation valve of the engine is provided on the recirculation line, and the control unit is configured to control the recircuation valve to be closed under a coasting driving condition.

14. The method of claim 13 , wherein a first catalyst unit disposed at one side of the exhaust line to reduce a harmful substance included in the exhaust gas, and the low pressure EGR line is branched at a downstream side of the first catalyst unit to be connected to the intake line.

Assignees

• Hyundai Motor Co Ltd

Inventors

• Kim Seung Hwan
• Park Jong Ii
• Choi Kwanhee
• Lim Hyun Jun
• Lee Joowon
• Han Dong Hee

Classifications

• F02B39/08

  Non-mechanical drives, e.g. fluid drives having variable gear ratio · CPC title

• F02D41/12

  for deceleration {(F02D41/0005, F02D41/107 take precedence)} · CPC title

• F02B39/10

  electric · CPC title

• F02D41/0007 Primary

  for control of turbo-charged or super-charged engines (control of the pumps per se F02B37/12) · CPC title

• F02M35/10268

  Heating, cooling or thermal insulating means (air coolers F02B29/04; thermal treatment of combustion-air, fuel or fuel-air mixture F02M31/00; details of the throttle valve housing F02D9/1035) · CPC title