This application claims priority from Patent Application No. 10 2007 038 882.0, filed Aug. 17, 2007, the entire disclosure of which is incorporated herein by reference.
The present invention relates to an exhaust-gas cooling device for an internal combustion engine, wherein the exhaust-gas cooling device comprises a housing with an exhaust-gas inlet, an exhaust-gas outlet, a valve device, and a U-shaped heat exchange unit including an outbound flow path and a return flow path.
An exhaust-gas cooling device of the above type is known from DE 10 2004 019 554 A1. In the embodiment illustrated in the document, the hot exhaust gas is first is fed into a so-called heat exchanger, and the heat exchanger comprises ribs extending in the flow direction and intended to provide an improved heat transition between the exhaust gas and the coolant. During the flow of the exhaust gas through this heat exchanger, the heat exchanger will be susceptible, along with the increasing temperature of the exhaust gas, to sooting and char depositions so that the flow through the heat exchanger will be impeded. The sooting tends to occur particularly in the return flow path of the U-shaped heat exchanger because, in that stretch of the path, the exhaust gas has already been considerably cooled. In an effort to accomplish an improved heat transition while at the same time reducing the sooting, further prior art documents, e.g. DE 20 2006 009 464 U1, have proposed to select a special arrangement of the ribs and/or a special shape of the ribs. However, none of these approaches have been found useful for basically preventing the sooting throughout the operating life of the heat exchanger.
Thus, it is an object of the invention to provide an exhaust-gas cooling device which is adapted to still further reduce the sooting in the heat exchanger unit, while effecting the reduction at the lowest possible expenditure for production and the lowest possible costs.
The above object is achieved in that the housing comprises, on the open side of the U-shaped heat exchange unit, a first, a second and a third chamber, wherein the first chamber provides a fluid connection from the exhaust-gas inlet to the second chamber, and the third chamber provides a fluid connection from the second chamber to the exhaust-gas outlet, wherein the valve device is arranged in the second chamber such that the second chamber can be divided into two partial chambers, wherein a first one of the partial chambers is arranged in fluid connection with the outbound flow path, and the second one of the partial chambers is arranged in fluid connection with the return flow path. In this manner, there is provided an exhaust-gas cooling device wherein, by simple actuation of the valve device, the direction of the flow through the U-shaped heat exchange unit can be quickly changed to the effect that the “cold” part of the heat exchange unit, i.e. the return flow path, will be subjected to hot exhaust gas and thus be cleaned.
According to a preferred embodiment, the valve device is configured as a centrally supported flap valve, with one flap being operatively connected to part-circular outer surfaces of the first and third chambers. In this manner, there is obtained an exhaust-gas cooling device that can be assembled in a particularly simple manner. In this regard, it is also advantageous if the housing consists of two housing halves, a first one of the housing halves accommodating the heat exchange unit and the second housing half having the valve device supported therein.
The present invention further relates to an exhaust-gas recirculation system provided with an exhaust-gas cooling device, wherein a bypass channel bypassing the heat exchange unit, and an exhaust-gas recirculation valve device are provided. In the system, the bypass channel can be provided separately from the exhaust gas cooling device or, as still to be described hereunder, be integrated into the device. The exhaust-gas recirculation valve is arranged upstream or downstream of the exhaust-gas cooling device in a known manner and is provided to control the quantity of the exhaust gas to be recirculated. With particular advantage, the bypass channel can be formed in the flap of the valve device.
As part of the present invention, there is further claimed a method for cleaning a U-shaped heat exchange unit of an exhaust-gas recirculation system wherein, in the cleaning mode, the return flow path is connected to an exhaust-gas inlet of the heat exchange unit, whereby the flow direction of the exhaust gas through the heat exchange unit is reversed such that a return flow path of the heat exchange unit is subjected to hot exhaust gas.
Thus, in accordance with a first illustrative embodiment of the invention, an exhaust-gas cooling device for an internal combustion engine is provided, wherein the exhaust-gas cooling device includes a housing (2) provided with an exhaust-gas inlet (3), an exhaust-gas outlet (4), a valve device (5), and a U-shaped heat exchange unit (6) including an outbound flow path (7) and a return flow path (8), wherein the housing (2) comprises, on the open side of the U-shaped heat exchange unit (6), a first (9), a second (10) and a third chamber (11), wherein the first chamber (9) provides a fluid connection from the exhaust-gas inlet (3) to the second chamber (10), and the third chamber (11) provides a fluid connection from the second chamber (10) to the exhaust-gas outlet (4), wherein the valve device (5) is arranged in the second chamber (10) so that the second chamber (10) can be divided into two partial chambers (17; 18), wherein a first one (17) of the partial chambers (17; 18) is arranged in fluid connection with the outbound flow path (7), and the second one (18) of the partial chambers (17; 18) is arranged in fluid connection with the return flow path (8). In accordance with a second illustrative embodiment of the invention, the first illustrative embodiment is modified so that the valve device (5) is configured as a centrally supported flap valve, with one flap (23) that is operatively connected to part-circular outer surfaces (21,22) of the first and third chambers (9,11). In accordance with a third illustrative embodiment of the present invention, the first illustrative embodiment is modified so that the housing comprises two housing halves (12,13), wherein a first one of the housing halves (12,13) accommodates the heat exchange unit (6) and the second one of the housing halves (12,13) has the valve device (5) supported therein.
In accordance with a fourth illustrative embodiment of the invention, the first illustrative embodiment is modified so that a bypass channel (20) bypassing the heat exchange unit (6) is provided, and so that an exhaust-gas recirculation valve device (5) is provided. In accordance with a fifth illustrative embodiment of the invention, the fourth illustrative embodiment is further modified so that the bypass channel (20) is arranged in the flap (23) of the valve device (5). In accordance with a sixth illustrative embodiment of the present invention, the fourth illustrative embodiment is further modified so that the bypass channel (20) is arranged in the flap (23) of the flap valve (5).
In accordance with a seventh embodiment of the present invention, a method for cleaning a U-shaped heat exchange unit of an exhaust-gas recirculation system is provided, wherein, in the cleaning mode, the return flow path (8) is connected to an exhaust-gas inlet (3) of the U-shaped heat exchange unit (6), whereby the flow direction of the exhaust gas through the U-shaped heat exchange unit (6) is reversed so that the return flow path (8) of the U-shaped heat exchange unit (6) is subjected to hot exhaust gas.
A preferred embodiment of the invention will be described in greater detail as follows with reference to the accompanying drawings.
The second housing shell 13 is configured to provide a first chamber 9, a second chamber 10 and a third chamber 11. The first chamber 9 provides a fluid connection from the exhaust-gas inlet 3 to the second chamber 10. The third chamber 11 provides a fluid connection from the second chamber 10 to the exhaust-gas outlet 4. Apart from the above connections, the second chamber 10 is provided with a connection to the outbound flow path 7 and a connection to the return flow path 8 of the U-shaped heat exchange unit 6. The valve device 5 is arranged in the second chamber 10 in such a manner that the second chamber 10 can be divided into two partial chambers 17,18, a first one 17 of the partial chambers 17; 18 being arranged in fluid connection with the outbound flow path 7, and the second partial chamber 18 being arranged in fluid connection with the return flow path 8.
A special embodiment and the operating principle of the exhaust-gas cooling device and respectively of an exhaust-gas recirculating system for an internal combustion engine can be derived from
Although the invention has been described and illustrated with reference to specific illustrative embodiments thereof, it is not intended that the invention be limited to those illustrative embodiments. Those skilled in the art will recognize that variations and modifications can be made without departing from the true scope of the invention as defined by the claims that follow. It is therefore intended to include within the invention all such variations and modifications as fall within the scope of the appended claims and equivalents thereof.
Number | Date | Country | Kind |
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10 2007 038 882 | Aug 2007 | DE | national |
Number | Name | Date | Kind |
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4543996 | Baron | Oct 1985 | A |
Number | Date | Country |
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10 2004 019 554 | Nov 2005 | DE |
103 55 649 | Dec 2005 | DE |
10 2005 006 055 | Aug 2006 | DE |
20 2006 009 464 | Oct 2006 | DE |
102007002459 | Jul 2007 | DE |
0 987 427 | Mar 2000 | EP |
2891590 | Apr 2007 | FR |
2891590 | Apr 2007 | FR |
2007039700 | Apr 2007 | WO |
2007039701 | Apr 2007 | WO |
2008101560 | Aug 2008 | WO |
Number | Date | Country | |
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20090044525 A1 | Feb 2009 | US |