GB2487591A

GB2487591A - An EGR cooler located in an air intake manifold

Info

Publication number: GB2487591A
Application number: GB1101568.2A
Authority: GB
Inventors: Fiorello Losano
Original assignee: GM Global Technology Operations LLC
Current assignee: GM Global Technology Operations LLC
Priority date: 2011-01-28
Filing date: 2011-01-28
Publication date: 2012-08-01
Anticipated expiration: 2031-01-28
Also published as: GB201101568D0; GB2487591B

Abstract

An internal combustion engine having a cylinder head 8 and equipped with an intake manifold 2, an exÂhaust manifold and an exhaust gas recirculation system (EGR) 6, the exhaust gas recirculation system comprising a conduit 60, located in the cylinder head 8, fluidly connecting the exhaust manifold to the intake manifold 2, and a cooler 61, fluidly conÂnected to the conduit 60 , and located in the intake manifold 2. The cooler may be connected to the engine coolant circuit 7 and the cooler outlet may have a venture tube 9 associated with it. Additionally a bypass conduit 62 and valve 622 may allow the recirculated exhaust gases to bypass the cooler, the bypass conduit and valve may also be located in the intake manifold.

Description

INTERNAL CCt4BUSTION ENGINE

WL FIElD

The present invention relates to an internal combustion engine, typi- cally an internal combustion engine of a motor vehicle, which is pro-vided with an exhaust gas recirculation system.

An internal combustion engine is conventionally provided with an in-take manifold, an exhaust manifold, an intake line for conveying fresh air from the environment into the intake manifold, and an ex-haust line for conveying the exhaust gas from the exhaust manifold to the environment.

In order to reduce the polluting emission, most internal combustion engines, principally Diesel engines, are further equipped with an ex-haust gas recirculation (EGR) system, for selectively routing back a part of the exhaust gas from the exhaust manifold into the intake ma-nifold.

In this way, the recirculated exhaust gas is mixed with the fresh in-duction air and is fed into the engine cylinders, thereby reducing the production of oxides of nitrogen (NO) during the combustion process.

Conventional EGR systems comprise an EGR conduit which fluidly con-nects the exhaust manifold with the intake manifold, an EGR cooler for cooling the exhaust gas before mixing it with the induction air, and a electronically controlled valve for regulating the flow rate of exhaust gas to be recirculated in the EGR conduit.

Nonetheless, the antipollution effect of the EGR system is strongly reduced if the recirculated exhaust gas is too cold, for example at the start of the engine, to the point that an overcooled exhaust gas can even deteriorate the corrbustion process.

For this reason, in order to accelerate the warm-up of the exhaust gas at the start of the engine, the EGR systems further comprise a bypass conduit, connected in parallel to the EGR cooler, and a fur- ther valve for selectively routing the exhaust gas to the bypass con-duit, thereby preventing the recirculated exhaust gas to be cooled inside the EGR cooler.

Providing the engine with an EGR system makes the engine layout com-plex considering the available space in the engine compartment whose volume is different for each vehicle system model. For this reason the EGR cooler is located, on the basis of the available space, close to the engine block but spaced apart from the intake manifold. This solution makes it necessary to provide conduits for fluidly connect-ing the cooler respectively to the coolant circuit and to the intake and exhaust manifolds. During the engine operation the connecting conduits are subjected to vibration which may cause the conduits to break with consequent leakage of coolant or exhaust gas. Furthermore the length of the conduits slows down the response time of the EGR system at the start of the engine due to the time the exhaust gas needs to pass through the conduits. Hence, at the start up, the en-gine produce pollutants before the EGR system can properly operate.

An object of an embodiment of the present invention is therefore to improve the engine layout of an engine equipped with an EGR system.

An object of an aspect of an embodiment of the invention is to reduce the response time of the EGR system at the start of the engine.

Another object of an aspect of the invention is to meet these goals by means of a simple, rational and low cost solution.

SIRY

These and/or other objects are achieved by the features of the embodiments of the invention as reported in the indepen-dent claim. The dependent claims recite preferred and/or particularly advantageous features of the embodiments of the invention.

In greater detail, an embodiment of the invention provides an internal combustion engine having a cylinder head and equipped with an intake manifold, an exhaust manifold and an exhaust gas re-circulation system, the exhaust gas recirculation system comprising a conduit that fluidly connects the exhaust manifold to the intake ma-nifold, and a cooler, fluidly connected to the conduit, and located in the intake manifold.

This solution allows to reduce the packaging issues inside the engine compartment of a vehicle.

According to an aspect of an embodiment of the invention the conduit is located in the cylinder head of the engine.

This solution advantageously allows to eliminate the need of exhaust gas external conduits reducing the risk of breaking of the conduits during the operation of the engine, as mentioned above, and to Ian-prove the engine layout.

According to another aspect of an embodiment of the invention the cooler comprises a tube bundle defining an internal chamber hydrauli-cally connected to an engine coolant circuit. This solution allows an effective cooling of the exhaust gas.

According to another aspect of an embodiment of the invention the cooler comprises a cooler inlet and a cooler outlet, a venturi tube being associated with the cooler outlet advantageously allowing a substantially homogeneous mixture between the exhaust gas and the fresh air in the intake manifold.

A different aspect of an embodiment of the invention provides the ex- haust gas recirculation system comprises a bypass conduit that fluid-ly connects the exhaust manifold to the intake manifold bypassing the cooler, and a valve for allowing the exhaust gas to flow through the bypass conduit.

This solution allows to reduce pollution emissions at the start of the engine.

A further aspect of an embodiment of the invention provides that the bypass conduit and the valve are located in the intake manifold al-lowing an extremely compact layout of the engine.

BRIEF DESCRIFIC2I OF THE DRAWINGS The various embodiments will now be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 schematically illustrates an internal combustion engine pro- vided with an exhaust gas recirculation system according to an embo-diment of the invention; Figure 2 schematically illustrates an enlarged view of a part of Fig.l in a first operating condition; Figure 3 schematically illustrates an enlarged view of a part of Fig.1 in a second operating condition.

DEThILED DESCRIFTIT OF THE DRAWINGS Figure 1 shows an internal combustion engine 1, in this case a Diesel engine.

The internal combustion engine 1 has an intake manifold 2 and an ex-haust manifold 3.

The intake manifold 2 is connected with an intake line 4 for convey- ing fresh air from the environment into the internal combustion en-gine 1, while the exhaust manifold 3 is conventionally connected with an exhaust line 5 for conveying the exhaust gas from the internal combustion engine 1 to the environment.

The internal combustion engine 1 is equipped with an exhaust gas re-circulation (EGR) system, globally indicated as 6, which is provided for routing back and feeding exhaust gas into the internal combustion engine to reduce the emission of nitrogen oxides (NO,J.

The EGR system 6 comprises a conduit 60 which fluidly connects the exhaust manifold 3 directly to the intake manifold 2, and a cooler 61, generally referred as EGR cooler, located in the intake manifold 2 and fluidly connected to the conduit 60, for cooling the exhaust gas flowing therein.

The cooler 61 is a conventional heat exchanger, by means of which the exhaust gas flowing in the conduit 60 is cooled by an engine coolant.

To this end the cooler 61 is hydraulically connected to an engine coolant circuit 7.

According to an aspect of the invention the conduit 60 is located in a cylinder head 8 of the engine 1 allowing an improved layout of the engine.

In greater details, the cooler 61 comprises an external casing 610 having a cooler inlet 611 and a coder outlet 612 for the exhaust gas, and a tube bundle 613 defining an internal chamber 614 for the coolant.

The tube bundle 613 comprises a plurality of tubes 615 having open ends hydraulically connected respectively to the cooler inlet 611 and to the cooler outlet 612 allowing the flowing of the exhaust gas through the tube bundle 613.

In this way, the cooler 61 allows the engine coolant to cool the ex-haust gas, keeping them physically separated.

A valve 616 is associated with the cooler inlet 611 in order to regu-late the flow rate of exhaust gas that is globally routed back from the exhaust manifold 3 to the intake manifold 2.

According to an aspect of the invention a venturi tube 9 is asso- ciated with the cooler outlet 612 enabling a substantially homogene-ous mixture between the exhaust gas and the fresh air.

The EGR system 6 further comprises a bypass conduit 62 connected in parallel to the cooler 61.

According to this embodiment of the invention the by-pass conduit 62 is located in the intake manifold 2 upstream the cooler 61 and it comprises a by-pass inlet 620 and a by-pass outlet 621 hydraulically connected respectively to the cooler inlet 611 and to the cooler out-let 612.

A valve 622 is associated with the by-pass inlet 620 for alternative-ly allowing or preventing the flowing of the exhaust gas through the bypass conduit 62.

While at least one exemplary embodiment has been presented in the foregoing summary and detailed description, it should be appreciated that a vast number of variations exist. It should also be appreciated that the exemplary embodiment or exemplary embodiments are only exam- ples, and are not intended to limit the scope, applicability, or con- figuration in any way. Rather, the foregoing summary and detailed de-scription will provide those skilled in the art with a convenient road map for implementing at least one exemplary embodiment, it being understood that various changes may be made in the function and ar-rangement of elements described in an exemplary embodiment without departing from the scope as set forth in the appended claims and their legal equivalents.

PEFERENCE NUMBERS

1 Internal combustion engine 2 Intake manifold 3 Exhaust manifold 4 intake line exhaust line 6 exhaust gas recirculation (EGR) system 7 engine coolant circuit 8 cylinder head 9 venturi tube conduit 61 Cooler 62 Bypass conduit 610 External casing 611 cooler inlet 612 cooler outlet 613 tube bundle 614 internal charter 615 tubes 616 valve 620 by-pass inlet 621 by-pass outlet 622 valve

Claims

1. Internal combustion engine (1) having a cylinder head (8) and equipped with an intake manifold (2), an exhaust manifold (3) and an exhaust gas recirculation system (6), the exhaust gas recircu-lation system (5) comprising a conduit (60), fluidly connecting the exhaust manifold (3) to the intake manifold (2), and a cooler (61), fluidly connected to the conduit (60), and located in the intake manifold (2).

2. Internal combustion engine according to claim 1, wherein the con-duit (60) is located in the cylinder head (8) of the engine (1).

3. Internal combustion engine according to claim 1, wherein the coo-ler (61) comprises a chamber (613) hydraulically connected to an engine coolant circuit (7).

4. Internal combustion engine according to claim 1, wherein the coo-ler (61) comprises a cooler inlet (611) and a cooler outlet (612), a venturi tube (9) being associated with the cooler outlet (612)

5. Internal combustion engine according to claim I, wherein the ex-haust gas recirculation system (6) comprises a bypass conduit (62) that fluidly connects the exhaust manifold (3) to the intake manifold (2) bypassing the cooler (61), and a valve (622) for al-lowing the exhaust gas to flow into the bypass conduit (62).

6. Internal combustion engine according to claim 5, wherein the by-pass conduit (62) and the valve (622) are located in the intake manifold (2).