GB2522130A

GB2522130A - Internal combustion engine for a vehicle

Info

Publication number: GB2522130A
Application number: GB1500940.0A
Authority: GB
Inventors: Vaijanath Mokashi
Original assignee: Daimler AG
Current assignee: Mercedes Benz Group AG
Priority date: 2015-01-20
Filing date: 2015-01-20
Publication date: 2015-07-15
Also published as: GB201500940D0

Abstract

The invention relates to an internal combustion engine 10 for a vehicle. The engine comprising of at least one air pipe 18 for guiding air to at least one combustion chamber 14 of the internal combustion engine and at least one exhaust pipe 28. The engine further comprises at least one compressor 20 arranged in the air pipe and at least one catalytic converter 34 arranged in the exhaust pipe. The engine further comprises at least one connection line 56 fluidically connected to the air pipe downstream of the compressor and fluidically connected to the exhaust pipe upstream of the catalytic converter. The connection line comprises two connection points 58 60, a two-way valve 62 being configured to allow both a flow of air from the air pipe into the exhaust pipe and a flow of exhaust gas from the exhaust pipe into the air pipe. The first connection point may be arranged upstream of a cooling device 52 in the air pipe. The two-way valve may be electronically controlled. The engine may during a warm-up phase be configured to branch off exhaust gas through the connection line into the air pipe.

Description

Internal combustion engine for a vehicle The invention relates to an internal combustion engine according to the preamble of patent claim 1.

Such an internal combustion engine for a vehicle can be found in US 2002/0083700 Al.

The internal combustion engine comprises at least one air pipe for guiding air to at least one combustion chamber of the internal combustion engine. For example, the air pipe is arranged in an intake system through which air can flow. Moreover, the internal combustion engine comprises at least one compressor arranged in the air pipe. The compressor is configured to compress the air flowing through the air pipe. The internal combustion engine further comprises at least one exhaust pipe through which exhaust gas of the internal combustion engine can flow. Furthermore, the internal combustion engine comprises at least one catalytic converter arranged in the exhaust pipe.

Additionally, the internal combustion engine comprises at least one connection line fluidically connected to the air pipe at a first connection point which is arranged downstream of the compressor with respect to a direction of flow of the air flowing through the air pipe. The connection line is also fluidically connected to the exhaust pipe at a second connection point which is arranged upstream of the catalytic converter with respect to a direction of flow of the exhaust gas flowing through the exhaust pipe.

It is an object of the present invention to further develop an internal combustion engine of the aforementioned kind in such a way that a particularly efficient operation of the internal combustion engine can be realized.

This object is solved by an internal combustion engine having the features of patent claim 1. Advantageous embodiments with expedient developments of the invention are indicated in the other patent claims.

In order to further develop an internal combustion engine of the kind indicated in the preamble of patent claim 1 in such a way that a particularly efficient operation of the internal combustion engine can be realized, according to the present invention the internal combustion engine comprises a two-way valve arranged in the connection line. The two-way valve is configured to allow both a flow of air from the air pipe through the connection line into the exhaust pipe, and a flow of exhaust gas from the exhaust pipe through the connection line into the air pipe. This means at least a portion of the exhaust gas flowing through the exhaust pipe can be branched off at the second connection point so that at least some of the exhaust gas can flow into the connection line. The branched off exhaust gas can flow through the connection line and into the air pipe so that the connection line acts as an EGH cooler bypass (EGR -Exhaust Gas Recirculation) since the exhaust gas flowing through the connection line is not cooled by a cooling device such as, for example, an EGR cooler. Thus, during warm-up phases of the internal combustion engine the internal combustion engine can be heated up particularly fast since a particularly high temperature of a gas flowing through the air pipe into at least one combustion chamber of the internal combustion engine can be realized by feeding the branched off exhaust gas into the air pipe. For example, the two-way valve and the connection line act as an EGR cooler bypass valve before turbo kick-in.

Moreover, at least a portion of the air flowing through the air pipe can be branched off at the first connection point by means of the connection line and the two-way valve so that at least a portion of the air can flow into the connection line at the first connection point. The air flowing through the connection line can flow into the exhaust pipe at the second connection point so that a particularly efficient and effective operation of the catalytic converter can be realized. For example, the catalytic converter is configured as an oxidation catalytic converter, in particular a diesel oxidation catalytic converter (DOC). By feeding air into the exhaust pipe a particular high amount of oxygen can be fed into the exhaust pipe upstream of the catalytic converter so that the efficiency of oxidation provided by the catalytic converter, in particular during a regeneration can be increased.

Moreover, emissions in high engine speed working areas can be kept particularly low.

Furthermore, the connection line and the two-way valve can help realize a quick pressure release during turbo surge.

Preferably, the two-way valve is configured as an electronically controlled and operated valve so that the flow of the air or the exhaust gas flowing through the connection line can be adjusted, in particular controlled, by the two-way valve in a need-based manner.

The flow of air through the connection line and the flow of exhaust gas through the connection line can be effected by respective pressure differences which can be adjusted in a need-based manner. For example, to guide air from the air pipe through the connection line to the exhaust pipe a first pressure at the first connection point in the air pipe is adjusted, the first pressure being higher than a second at the second connection point pressure in the exhaust pipe. In order to guide exhaust gas from the exhaust pipe through the connection line to the air pipe the second pressure at the second connection point in the exhaust pipe is adjusted to be higher than the first pressure at the first connection point in the air pipe. Thus, a particularly efficient operation of the internal combustion engine can be realized particularly easily and with a particularly low number of parts. Moreover, the emissions of the internal combustion engine can be kept particularly low.

Further advantages, features, and details of the invention derive from the following description of a preferred embodiment as well as from the drawing. The features and features combinations previously mentioned in the description as well as the features and features combinations mentioned in the following description of the figure and/or shown in the figure alone can be employed not only in the respective indicated combination but also in any other combination or taken alone without leaving the scope of the invention.

The drawing shows in the only Fig. a schematic view of an internal combustion engine comprising a connection line which is fluidically connected to an air pipe and an exhaust pipe, wherein a two-way valve is arranged in the connection line, the two-way valve being configured to allow both a flow of air and a flow of exhaust gas through the connection line.

The only Fig. shows an internal combustion engine 10 which is, for example, configured as a diesel engine. The internal combustion engine 10 comprises a cylinder housing 12 having combustion chambers in the form of cylinders 14. Moreover, the internal combustion engine 10 has an intake system 16 through which air can flow. Said air is guided to the cylinders 14 by means of the intake system 16. For this purpose, the intake system 16 comprises at least one air pipe 18 through which the air can flow, the air pipe 18 serving for guiding the air to the cylinders 14. The internal combustion engine 10 comprises a compressor 20 arranged in the air pipe 18 and configured to compress the air flowing through the air pipe 18. For example, the compressor 20 can be a compressor of a supercharger by means of which the cylinders 14 can be supplied with compressed air. In the present case, the compressor 20 is a compressor of a turbocharger 22 which also comprises a turbine 24. The internal combustion engine 10 comprises an exhaust tract 26 through which exhaust gas of the internal combustion engine 10 can flow. The exhaust tract 26 comprises an exhaust pipe 28 in which the turbine 24 is arranged.

Exhaust gas can flow through the exhaust pipe 28 and is guided by the exhaust pipe 28.

The exhaust gas can drive the turbine 24 which is connected to the compressor 20 by a shaft 30 of the turbocharger 22. Thereby, the compressor 20 can be driven by the turbine 24 so that energy contained in the exhaust gas can be used to compress the air flowing through the air pipe 18. For example, the turbine 24 has a variable turbine geometry (VTG) so that a flow cross-section of the turbine 24 can be adjusted in a need-based manner, wherein the exhaust gas flows through said flow cross-section. Alternatively or additionally, the turbine 24 can comprise a waste gate having at least one bypass line for bypassing the turbine 24. Moreover, alternatively or additionally, the turbocharger 22 can be configured as a two stage turbocharger.

The internal combustion engine 10 comprises an exhaust gas aftertreatment device 32 which is arranged in the exhaust pipe 28 downstream of the turbine 24 with respect to a direction of flow of the exhaust gas flowing through the exhaust pipe 28. In the present case, the exhaust gas aftertreatment device 32 comprises a catalytic converter 34 which is configured as an oxidation catalytic converter in the form of a diesel oxidation catalytic converter (DCC). Moreover, the exhaust gas aftertreatment device 32 comprises a particulate filter 36 in the form of a diesel particulate filter (DPF). The exhaust gas aftertreatrnent device 32 can comprise a particulate oxidation catalytic converter (P00), and/or a SCR catalytic converter and/or a NOx storage converter (NSC) and/or a lean NOx trap (LNT). The internal combustion engine 10 further comprises an EGR system 37 (EGR -Exhaust Gas Recirculation), wherein the EGR system 37 comprises an EGR line 38 which is fluidically connected to the exhaust pipe 28 at a connection point 40.

Moreover, the EGR line 38 is fluidically connected to the air pipe 18 at a connection point 42. The EGR system 37 further comprises an EGR valve 44 and an EGR cooler 46. By means of the EGR system 37 at least a portion of the exhaust gas flowing through the exhaust pipe 28 can be branched off at the connection point 40. Thus, at least a portion of the exhaust gas flowing through the exhaust pipe 28 can flow into the EGR line 38 at the connection point 40. The branched off exhaust gas is guided by the EGR line 38 to the connection point 42. Thus, at the connection point 42, the exhaust gas flowing through the EGR line 38 can flow out of the EGR line 38 and into the air pipe 18 at the connection point 42. The EGR valve 44 is used to adjust the amount of exhaust gas flowing through the EGR line 38. The EGR cooler 46 is arranged downstream of the EGR valve 44 and configured to cool the exhaust gas flowing through the EGR line 38.

The intake system 16 comprises an air filter 48 and an air flow meter 50 arranged in the air pipe 18. The air flowing through the intake system 16 has a pressure p0 and a temperature TO upstream of the air filter 48. At the air flow meter 50 the air has a pressure p1 and a temperature Ti. Between the compressor 20 and a cooling device 52 arranged in the air pipe 18 the air has a pressure p20. By compressing the air, the air is heated up by the compressor 20. The cooling device 52 which is also referred to as an intercooler is configured to cool the compressed air.

The intake system 16 further comprises a throttle valve 54 arranged in the air pipe 18.

The throttle valve 54 is used to adjust a pressure of the air in the air pipe 18. Between the intercooler and the throttle valve 54 the air has a pressure p2i and a temperature T21.

Between the connection point 40 and the turbine 24 the exhaust gas has a pressure p3.

Between the turbine 24 and the catalytic converter 34 the exhaust gas has a pressure p4.

As can be seen from the Fig., the internal combustion engine 10 further comprises a connection line 56 being different from the EGR line 38. The connection line 56 is fluidically connected to the air pipe i8 at a connection point 58 which is arranged downstream of the compressor 20 and upstream of the cooling device 52. Moreover, the connection line 56 is fluidically connected to the exhaust pipe 28 at a connection point 60 which is arranged downstream of the turbine 24 and upstream of the catalytic converter 34.

The internal combustion engine 10 further comprises a two-way valve 62 arranged in the connection line 56. The two-way valve 62 is configured to allow both a flow of air from the air pipe 18 through the connection line 56 into the exhaust pipe 28, and a flow of exhaust gas from the exhaust pipe 28 through the connection line 56 into the air pipe i8, in particular on the basis of a pressure difference at the connection points 58 and 60. The two-way valve 62 is configured as an electronically controlled and operated valve so that an amount of the air and an amount of the exhaust gas flowing through the connection line 56 can be adjusted in a need-based manner by means of the two-way valve 62.

Preferably, during a warm-up phase of the internal combustion engine, the internal combustion engine is configured to branch off the exhaust gas at the connection point 60, guide the branched off exhaust gas through the connection line 56 and feed the branched off exhaust gas into the air pipe 18 at the connection point 58 so that the internal combustion engine 10 can be heated up particularly quickly.

For example, the internal combustion engine 10 is operated in a first operation mode in order to keep emissions particularly low during DPE regeneration, DCC heat up and high engine speed. For this purpose the variable turbine geometry and the throttle valve 54 are adjusted in such a way or moved in such positions that a pressure downstream of the compressor 20 is increased. Moreover, the two-way valve 62 is opened so that fresh air can flow from the connection point 58 to the connection point 60 upstream of the catalytic converter 34. The air which is fed into the exhaust pipe 28 is also referred to as secondary air which helps the oxidation of unburned hydro carbons (HO), unburned fuel and additional injected fuel (post or HG injections) to increase the temperature of the catalytic converter 34. Thus, the conversion efficiency increases due to a high amount of oxygen content available in the exhaust gas for exothermic reaction.

In the first operation mode, for example, the throttle valve 54 is closed partially in order to realize a particularly high pressure at the connection point 58 so that the pressure at the connection point 58 is higher than the pressure at the connection point 60. Moreover, the variable turbine geometry can be closed at least partially to realize a high boost of the turbocharger 22 and a pressure drop at the connection point 60 downstream of the turbine 24.

Furthermore, the internal combustion engine can be operated in a second operation mode in which exhaust gas is branched off at the connection point 60, guided through the connection line 56 and fed into the air pipe 18 at the connection point 58. Thus, the connection line 56 acts as exhaust gas recirculation cooler bypass so that the internal combustion engine can be heated up particularly quickly at cold starts. In the second operation mode, for example, the variable turbine geometry is widely opened so that the pressure at the connection point 60 is higher than the pressure at the connection point 58.

For example, during low idle engine RPM boost is not possible as exhaust pressure energy is not sufficient to drive the turbine 24. However, the pressure at the connection point 60 is higher than the pressure at the connection point 58 so that with the two-way valve 62 opened and the variable turbine geometry opened, exhaust gas can be recirculated to the intake pipe 18 to heat up the internal combustion engine 10. Thus, the air flowing through the intake pipe 18 is heated by the exhaust gas fed into the air pipe 18.

Moreover, the internal combustion engine 10 can be operated in a third operation mode in which a quick turbo or compressor surge reduction can be realized. In the third operation mode air flowing through the air pipe 18 is branched off at the connection point 58, guided through the connection line 56 and fed into the exhaust pipe 28 at the connection point 60. When the driver releases the accelerator pedal suddenly at high load a back pressure will be created to oppose the compressor rotation, known as compressor surge. Hence, the two-way valve 62 is opened during surge condition to release the excessive air and protect the turbocharger 22 from damage.

List of reference signs internal combustion engine 12 cylinder housing 14 cylinder 16 intake system 18 air pipe compressor 22 turbocharger 24 turbine 26 exhaust tract 28 exhaust pipe shaft 32 exhaust gas aftertreatment device 34 catalytic converter 36 particulate filter 37 EGR system 38 EGR line connection point 42 connection point 44 EGH valve 46 EGH cooler 48 air filter air flow meter 52 cooling device 54 throttle valve 56 connection line 58 connection point connection pont 62 two-way valve

Claims

UClaims An internal combustion engine (10) for a vehicle, the internal combustion engine (10) comprising: -at least one air pipe (18) for guiding air to at least one combustion chamber (14) of the internal combustion engine (10); -at least one compressor (20) arranged in the air pipe (18), the compressor (20) being configured to compress the air flowing through the air pipe (18); -at least one exhaust pipe (28) through which exhaust gas of the internal combustion engine (10) can flow; -at least one catalytic converter (34) arranged in the exhaust pipe (28); and -at least one connection line (56) fluidically connected to the air pipe (18) at a first connection point (58) arranged downstream of the compressor (20), the connection line (56) being fluidically connected to the exhaust pipe (28) at a second connection point (60) arranged upstream of the catalytic converter (34); characterized in that internal combustion engine (10) comprises a two-way valve (62) arranged in the connection line (56), the two-way valve (62) being configured to allow both a flow of air from the air pipe (18) through the connection line (56) into the exhaust pipe (28), and a flow of exhaust gas from the exhaust pipe (28) through the connection line (56) into the air pipe (18).
2. The internal combustion engine (10) according to claim 1, characterized in that the two-way valve (62) is configured as an electronically controlled and operated valve.
3. The internal combustion engine (10) according to claim 1 or 2, characterized in that during a warm-up phase, the internal combustion engine (10) is configured to branch off exhaust gas at the second connection point (60), guide the branched off exhaust gas through the connection line (56) and feed the branched off exhaust gas into the air pipe (18) at the first connection point (58).
4. The internal combustion engine (10) according to any one of the preceding claims, characterized in that the first connection point (58) is arranged upstream of a cooling device (52) arranged in the air pipe (18).
5. A vehicle comprising an internal combustion engine (10) according to any one of the preceding claims.