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EP 1 251 263 B1 |
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EUROPEAN PATENT SPECIFICATION |
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Mention of the grant of the patent: |
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25.01.2006 Bulletin 2006/04 |
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Date of filing: 25.03.2002 |
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International Patent Classification (IPC):
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Device for exhaust gas recirculation
Vorrichtung für Abgasrückführung
Dispositif pour recirculation de gaz d'échappement
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Designated Contracting States: |
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AT BE CH CY DE DK ES FI FR GB GR IE IT LI LU MC NL PT SE TR |
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Priority: |
20.04.2001 LU 90761
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Date of publication of application: |
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23.10.2002 Bulletin 2002/43 |
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Proprietor: Delphi Technologies, Inc. |
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Troy, MI 48007 (US) |
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Inventors: |
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- Collins, Laurence A.D.
6792 Rachecourt (BE)
- Fromentin, Sylvie F.
8447 Steinfort (LU)
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Representative: Beissel, Jean |
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Office Ernest T. Freylinger S.A.,
234, route d'Arlon,
B.P. 48 8001 Strassen 8001 Strassen (LU) |
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References cited: :
EP-A- 0 916 837 WO-A-01/20156 DE-A- 19 841 927
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WO-A-00/68560 WO-A-01/44651
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Note: Within nine months from the publication of the mention of the grant of the European
patent, any person may give notice to the European Patent Office of opposition to
the European patent
granted. Notice of opposition shall be filed in a written reasoned statement. It shall
not be deemed to
have been filed until the opposition fee has been paid. (Art. 99(1) European Patent
Convention).
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Introduction
[0001] The present invention relates to a device for exhaust gas recirculation for an internal
combustion engine, especially to a cooler and a valve for exhaust gas recirculation.
[0002] Exhaust gas recirculation is a technique commonly used for controlling the generation
of undesirable pollutant gases and particulate matter in the operation of internal
combustion engines. This technique has proven particularly useful in diesel internal
combustion engines used in motor vehicles such as passenger cars, trucks, and other
on-road or off-road motor equipment. The exhaust gas recirculation technique primarily
involves the recirculation of exhaust gas by-products into the intake air supply of
the internal combustion engine. This exhaust gas thus reiritroduced to the engine
cylinder reduces the concentration of oxygen therein, which in turn lowers the maximum
combustion temperature within the cylinder and slows the chemical reaction of the
combustion process, decreasing the formation of oxides of nitrogen NOx. Furthermore,
the exhaust gases typically contain a portion of unburned hydrocarbon which is burned
on its reintroduction into the engine cylinder, which further reduces the emission
of exhaust gas by-products which would be emitted as undesirable pollutants from the
internal combustion engine.
[0003] A device for exhaust gas recirculation generally includes an intake air tube, an
intake air control valve and an exhaust gas re-circulation valve. The intake air control
valve allows for the throttling the intake airflow in the intake air tube. The exhaust
gas re-circulation valve meters the flow of exhaust gases re-circulated into the intake
air tube. In order to further reduce the combustion temperature of the engine, an
exhaust gas cooler is moreover provided for cooling the exhaust gases to be fed into
the engine air intake.
[0004] In heavy duty diesel engines, the exhaust gas recirculation device is often mounted
upstream of the EGR cooler, i.e. on the hot gas side of the cooler. This requires
that the EGR valve is made of special heat-resistant materials able to withstand exhaust
gas temperatures up to 800°C. It is clear that the use of such heat-resisting materials
considerably increases the costs of the EGR valve.
[0005] In order to reduce the temperature at the EGR valve, it was proposed to provide the
exhaust gas recirculation valve with at least one cooling circuit which is supplied
with cooling fluid from the exhaust gas cooler. EGR systems of this kind are e.g.
disclosed in WO-A-01/44651 and WO-A-01/20156.
Object of the invention
[0006] The technical problem underlying the present invention is to provide an improved
exhaust gas re-circulation device for an internal combustion engine.
General description of the invention
[0007] This problem is overcome by the exhaust gas recirculation device for an internal
combustion engine according to the present invention. This exhaust gas recirculation
device comprises an exhaust gas recirculation conduit for feeding exhaust gases to
an intake air channel of said engine, an exhaust gas recirculation valve arranged
in said exhaust gas recirculation conduit for controlling the amount of exhaust gases
fed into said intake air channel, and an exhaust gas cooler arranged in said exhaust
gas re-circulation conduit for cooling the exhaust gas fed into said intake air channel,
said exhaust gas cooler comprising a cooling circuit for a cooling fluid. The exhaust
gas recirculation valve comprises at least one cooling circuit for a cooling fluid,
said cooling circuit of said exhaust gas recirculation valve being connected to said
cooling circuit of said exhaust gas cooler. According to the invention, the exhaust
gas recirculation valve comprises an actuatable valve member, which is rotatably mounted
into a flow path for said exhaust gas by means of bearings. In order to provide an
adequate cooling of the exhaust gas recirculation valve, the cooling circuit of said
exhaust gas recirculation valve preferably at least partially surrounds said flow
path and/or said bearings of said actuatable valve member.
[0008] During the operation of the device, a cooling fluid is flooded through the cooling
circuit of the exhaust gas cooler. The cooling circuit of the exhaust gas cooler being
connected to the cooling circuit of the exhaust gas recirculation valve, this cooling
fluid is also flooded through the cooling circuit of the exhaust gas recirculation
valve. It follows that the components of the exhaust gas recirculation valve are cooled
during the operation of the device, thus allowing the specification of cheaper materials.
Furthermore, by using the cooling fluid directly from the exhaust gas cooler, the
use of supplementary pipework is reduced to a minimum.
[0009] It has to be noted that the direction of the flow of the cooling fluid may depend
on the cooling requirements for the exhaust gas recirculation valve. If improved cooling
of the exhaust gas recirculation valve is required, the cooling fluid can be fed into
the cooling circuit of the exhaust gas recirculation valve before entering the cooling
circuit of the exhaust gas cooler. Alternatively, the flow of cooling fluid can first
enter the cooling circuit of the exhaust gas cooler before entering the exhaust gas
recirculation valve.
[0010] Traditionally, the EGR cooler and the EGR valve are supplied as separate components,
each being provided with two mounting flanges. The EGR cooler and valve are then mounted
together, either directly or by means of supplementary pipework. In a preferred embodiment
of the invention, said exhaust gas recirculation valve and said exhaust gas cooler
are integrated into one single housing. Such an integration of the valve and cooler
provides for a very compact exhaust gas recirculation device. Furthermore, this embodiment
eliminates the need for later assembly of two separate parts and accordingly the risk
of defects in assembling. In addition, the number of parts like joints, bolts etc.
is reduced. It follows that this embodiment reduces the costs of the exhaust gas recirculation
device and at the same time improves the quality of the product. It will be further
appreciated that component costs, size and weight are important considerations in
automotive vehicle applications. An exhaust gas re-circulation device that is more
compact in size can be of advantage, because of limitations on available space in
a vehicle engine compartment. Weight reductions of components help of course to reduce
fuel consumption of the vehicle.
[0011] The exhaust gas cooler usually comprises a housing defining a flow path for said
exhaust gases, said flow path having an enlarged central portion and two tapered end
portions. In this case, the integration of the valve and the cooler is preferably
achieved by integrating said exhaust gas recirculation valve into one of said end
portions of said flow path of said exhaust gas cooler.
[0012] A further advantage of the integrated design of the valve and the cooler is that
the interconnection of the respective cooling circuits of the exhaust gas recirculation
valve and exhaust gas cooler is simplified. In fact, the transfer of coolant between
the two cooling circuits can be achieved by a simple duct. In a first embodiment,
this duct can comprise an external coolant duct which extends outside of said single
housing. The external duct can simply be connected to respective fittings on the exhaust
gas recirculation valve cooling circuit and the exhaust gas cooler cooling circuit.
In an alternative embodiment, the duct may be an internal coolant duct, which is arranged
inside said single housing.
[0013] It will be further appreciated that component costs, size and weight are important
considerations in automotive vehicle applications. An exhaust gas recirculation device
that is more compact in size can be of advantage, because of limitations on available
space in a vehicle engine compartment. Weight reductions of components help of course
to reduce fuel consumption of the vehicle.
Detailed description with respect to the figures
[0014] The present invention will be more apparent from the following description of a not
limiting embodiment with reference to the attached drawings, wherein
- Fig.1:
- shows an end portion of an embodiment of an exhaust gas recirculation device according
to the present invention; and
- Fig.2:
- shows an inside view of the device of fig. 1.
[0015] An embodiment of an exhaust gas recirculation device 10 according to the present
invention is represented in fig. 1 and 2. These figures show an end portion of an
integrated exhaust gas recirculation cooler and valve, i.e. an exhaust gas cooler
12 having an exhaust gas recirculation valve 14 integrated therein.
[0016] The exhaust gas cooler 12 typically comprises a housing 16 having a plurality of
hollow tubes 18 arranged therein in a substantially parallel relationship. These hollow
tubes 18 define a plurality of flow paths for the exhaust gas to be transferred through
the exhaust gas cooler. The areas surrounding the hollow tubes define a coolant circuit
20 for a cooling fluid supplied by a (non shown) coolant fluid source. Fittings 21
(only one is shown) are mounted in the housing 16 of the exhaust gas cooler 12 for
connecting the coolant circuit 20 to a coolant feeding or discharge conduit.
[0017] At each end, the exhaust gas cooler further comprises an end portion 22 having a
tapered inner form. The taper of the end portions reduces the diameter of the flow
path for the exhaust gases to the diameter of an exhaust gas recirculation conduit
24, and thus enables the exhaust gas cooler to be connected to said exhaust gas recirculation
conduit 24.
[0018] In the shown embodiment, the end portion 22 of the exhaust gas cooler is designed
as a double walled housing having an outer wall 26 and a coaxial inner wall 28, the
inner wall 28 being tapered towards the end of the cooler. The two coaxial walls 26
and 28 confine an annular cooling channel 30, which at least partially surrounds the
flow path defined by the inner wall 28. At the end of the exhaust gas cooler, the
cooling channel 30 is closed by an end plate 32, which is sealingly mounted onto the
front end of the end portion 22 of the exhaust gas cooler 12. The end plate can be
bolted onto the front end of cooler 12.
[0019] Two fittings 34 and 36 are mounted into the outer wall 26 of the end portion 22.
These fittings are used to connect the cooling channel 30 to a coolant feeding or
discharge conduit. In the shown embodiment, fitting 34 is connected to fitting 21
of the coolant circuit 20 by means of conduit. It follows that a coolant fluid, which
is supplied to the exhaust gas recirculation device 10 subsequently flows through
the two cooling circuits 20 and 30.
[0020] In the exhaust gas recirculation device 10 of fig. 1 and 2, an exhaust gas recirculation
valve 14 is integrated into the end portion 22 of the exhaust gas cooler 12. The exhaust
gas recirculation valve 22, e.g. a butterfly valve, comprises an acutatable member
40, which is arranged into the flow path defined by the inner wall 28 of end portion
22 of the exhaust gas cooler 12. The valve member 40 is mounted on a shaft 42, which
is rotatably mounted into the housing by means of bearings 44. The bearings are preferably
arranged in bushings 46, which radially extend through the cooling circuit 30. It
follows that the cooling circuit 30 at least partially surrounds bushings 46. In operation,
the bushings 46 are fully exposed to the flow of coolant fluid circulating in the
cooling circuit 30. This results in an effective cooling of the bearings 44 located
inside the bushings 46, since the different elements are preferably made of thermally
conductive metal.
[0021] Shaft 42 comprises an actuating end 48, which extends outside wall 26. This actuating
end 48 can be connected to an actuator 50 for actuating the valve member 40. In the
shown embodiment, actuator 50 is mounted on the housing of exhaust gas cooler adjacent
to actuating end 48. The (non shown) connection between the actuator and the actuating
end may be achieved by a cam means 52 mounted on the actuating end 48 of shaft 42,
cam means mounted on a shaft of the actuator and a connecting rod for coupling the
two cam means.
1. Exhaust gas recirculation device (10) for an internal combustion engine, comprising
an exhaust gas recirculation conduit (24) for feeding exhaust gases to an intake air
channel of said engine,
an exhaust gas cooler (12) arranged in said exhaust gas re-circulation conduit (24)
for cooling the exhaust gas fed into said intake air channel, said exhaust gas cooler
(12) comprising a cooling circuit (20) for a cooling fluid, and
an exhaust gas recirculation valve (14) arranged in said exhaust gas recirculation
conduit (24) for controlling the amount of exhaust gases fed into said intake air
channel, said exhaust gas recirculation valve (14) comprising at least one cooling
circuit (30) for a cooling fluid, said cooling circuit (30) of said exhaust gas recirculation
valve (14) being connected to said cooling circuit (20) of said exhaust gas cooler
(12),
characterized in that
said exhaust gas recirculation valve (14) comprises an actuatable valve member (40),
which is rotatably mounted into a flow path for said exhaust gas by means of bearings
(44), and wherein said cooling circuit (30) of said exhaust gas recirculation valve
(14) at least partially surrounds said bearings (44) of said actuatable valve member
(40).
2. Exhaust gas recirculation device (10) according to claim 1, wherein said exhaust gas
recirculation valve (14) and said exhaust gas cooler (12) are integrated into one
single housing (16).
3. Exhaust gas recirculation device (10) according to claim 2, wherein said exhaust gas
cooler (12) comprises a housing (16) defining a flow path for said exhaust gases,
said flow path having an enlarged central portion and two tapered end portions (22),
and wherein said exhaust gas recirculation valve (14) is integrated into one of said
end portions (22) of said flow path of said exhaust gas cooler (12).
4. Exhaust gas recirculation device (10) according to claim 2 or 3, wherein said cooling
circuit (30) of said exhaust gas recirculation valve (14) and said cooling circuit
(20) of said exhaust gas cooler (12) are connected by an external coolant duct (38),
said external coolant duct (38) extending outside of said single housing (16).
5. Exhaust gas recirculation device (10) according to claim 2 or 3, wherein said cooling
circuit (30) of said exhaust gas recirculation valve (14) and said cooling circuit
(20) of said exhaust gas cooler (12) are connected by an internal coolant duct, said
internal coolant duct being arrange inside said single housing (16).
6. Exhaust gas recirculation device (10) according to any one of the preceding claims,
wherein said cooling circuit (30) of said exhaust gas recirculation valve (14) at
least partially surrounds said flow path.
1. Abgasrückführvorrichtung (10) für einen Verbrennungsmotor, umfassend eine Abgasrückführleitung
(24), um Abgase einem Ansaugluftkanal des Motors zuzuführen;
einen Abgaskühler (12), der in der Abgasrückführleitung (24) angeordnet ist, um das
in den Ansaugluftkanal geführte Abgas zu kühlen, wobei der Abgaskühler (12) einen
Kühlkreislauf (20) für eine Kühlflüssigkeit umfasst; und
ein Abgasrückführventil (14), das in der Abgasrückführleitung (24) angeordnet ist,
um die Menge von in den Ansaugluftkanal geführten Abgasen zu regeln, wobei das Abgasrückführventil
(14) mindestens einen Kühlkreislauf (30) für eine Kühlflüssigkeit umfasst, wobei der
Kühlkreislauf (30) des Abgasrückführventils (14) mit dem Kühlkreislauf (20) des Abgaskühlers
(12) verbunden ist;
dadurch gekennzeichnet, dass
das Abgasrückführventil (14) ein betätigbares Ventilelement (40) umfasst, das über
Lager (44) drehbar in einem Strömungsweg für das Abgas befestigt ist, und wobei der
Kühlkreislauf (30) des Abgasrückführventils (14) zumindest teilweise die Lager (44)
des betätigbaren Ventilelements (40) umgibt.
2. Abgasrückführvorrichtung (10) nach Anspruch 1, wobei das Abgasrückführventil (14)
und der Abgaskühler (12) in ein einzelnes Gehäuse (16) integriert sind.
3. Abgasrückführvorrichtung (10) nach Anspruch 2, wobei der Abgaskühler (12) ein Gehäuse
(16) umfasst, das einen Strömungsweg für die Abgase definiert, wobei der Strömungsweg
einen vergrößerten Mittelabschnitt und zwei kegelförmige Endabschnitte (22) aufweist,
und wobei das Abgasrückführventil (14) in einen der Endabschnitte (22) des Strömungswegs
des Abgaskühlers (12) integriert ist.
4. Abgasrückführvorrichtung (10) nach Anspruch 2 oder 3, wobei der Kühlkreislauf (30)
des Abgasrückführventils (14) und der Kühlkreislauf (20) des Abgaskühlers (12) über
ein äußeres Kühlmittelrohr (38) verbunden sind, wobei das äußere Kühlmittelrohr (38)
außerhalb des einzelnen Gehäuses (16) verläuft.
5. Abgasrückführvorrichtung (10) nach Anspruch 2 oder 3, wobei der Kühlkreislauf (30)
des Abgasrückführventils (14) und der Kühlkreislauf (20) des Abgaskühlers (12) über
ein inneres Kühlmittelrohr verbunden sind, wobei das innere Kühlmittelrohr im Innern
des einzelnen Gehäuse (16) angeordnet ist.
6. Abgasrückführvorrichtung (10) nach irgendeinem der vorangehenden Ansprüche, wobei
der Kühlkreislauf (30) des Abgasrückführventils (14) zumindest teilweise den Strömungsweg
umgibt.
1. Dispositif de recirculation de gaz d'échappement (10) pour un moteur à combustion
interne, comprenant :
un conduit de recirculation de gaz d'échappement (24) pour amener un gaz d'échappement
à un canal d'air d'admission dudit moteur,
un refroidisseur de gaz d'échappement (12) installé dans ledit conduit de recirculation
de gaz d'échappement (24) pour refroidir le gaz d'échappement amené dans ledit canal
d'air d'admission, ledit refroidisseur de gaz d'échappement (12) comprenant un circuit
de refroidissement (20) pour un fluide de refroidissement,
et
une soupape de recirculation de gaz d'échappement (14) installée dans ledit conduit
de recirculation de gaz d'échappement (24) pour contrôler la quantité du gaz d'échappement
amené dans ledit canal d'air d'admission, ladite soupape de recirculation de gaz d'échappement
(14) comprend au moins un circuit de refroidissement (30) pour un fluide de refroidissement,
ledit circuit de refroidissement (30) de ladite soupape de recirculation de gaz d'échappement
(14) étant connecté audit circuit de refroidissement (20) dudit refroidisseur de gaz
d'échappement (12),
caractérisé en ce que
ladite soupape de recirculation de gaz d'échappement (14) comprend un élément de soupape
actionnable (40), qui est monté de façon à pouvoir tourner dans un passage d'écoulement
pour ledit gaz d'échappement au moyen de paliers (44), et dans lequel ledit circuit
de refroidissement (30) de ladite soupape de recirculation de gaz d'échappement (14)
entoure au moins partiellement lesdits paliers (44) dudit élément de soupape actionnable
(40).
2. Dispositif de recirculation de gaz d'échappement (10) selon la revendication 1, dans
lequel ladite soupape de recirculation de gaz d'échappement (14) et ledit refroidisseur
de gaz d'échappement (12) sont intégrés dans un même boîtier (16).
3. Dispositif de recirculation de gaz d'échappement (10) selon la revendication 2, dans
lequel ledit refroidisseur de gaz d'échappement (12) comprend un boîtier (16) définissant
un passage d'écoulement pour lesdits gaz d'échappement, ledit passage d'écoulement
ayant une partie centrale élargie et deux parties d'extrémité effilées (22), et dans
lequel ladite soupape de recirculation de gaz d'échappement (14) est intégrée dans
une desdites parties d'extrémité (22) dudit passage d'écoulement dudit refroidisseur
de gaz d'échappement (12).
4. Dispositif de recirculation de gaz d'échappement (10) selon la revendication 2 ou
3, dans lequel ledit circuit de refroidissement (30) de ladite soupape de recirculation
de gaz d'échappement (14) et ledit circuit de refroidissement (20) dudit refroidisseur
de gaz d'échappement (12) sont connectés par un conduit de fluide de refroidissement
externe (38), ledit conduit de fluide de refroidissement externe (38) s'étendant à
l'extérieur dudit boîtier unique (16).
5. Dispositif de recirculation de gaz d'échappement (10) selon la revendication 2 ou
3, dans lequel ledit circuit de refroidissement (30) de ladite soupape de recirculation
de gaz d'échappement (14) et ledit circuit de refroidissement (20) dudit refroidisseur
de gaz d'échappement (12) sont connectés par un conduit de fluide de refroidissement
inteme, ledit conduit de fluide de refroidissement inteme étant disposé à l'intérieur
dudit boîtier unique (16).
6. Dispositif de recirculation de gaz d'échappement (10) selon l'une quelconque des revendications
précédentes, dans lequel ledit circuit de refroidissement (30) de ladite soupape de
recirculation de gaz d'échappement (14) entoure au moins partiellement ledit passage
d'écoulement.