GB2526594A

GB2526594A - A device for connecting an exhaust gas recirculation conduit to an intake pipe

Info

Publication number: GB2526594A
Application number: GB1409520.2A
Authority: GB
Inventors: Lorenzo Magro; Richard M Frank
Original assignee: GM Global Technology Operations LLC
Current assignee: GM Global Technology Operations LLC
Priority date: 2014-05-29
Filing date: 2014-05-29
Publication date: 2015-12-02
Also published as: GB201409520D0

Abstract

A device 200 for connecting an exhaust-gas-recirculation (EGR) conduit (170, fig. 1) to an intake pipe (110, fig. 1) of an internal combustion engine. The device comprising an external housing 205 having a inlet 220 for connection with the intake pipe (110) and a second inlet 225 for connection with the EGR conduit (170). An inner volume 215 of the external housing 205 being divided by a tubular partition wall 235 into a central conduit 255 in communication with the first inlet 220 and an annular chamber 260 surrounding the central conduit 255 and in communication with inlet 225, the tubular partition wall 235 comprising radial openings 265 through which the chamber 260 is in communication with the central conduit 255.Â The device may also comprise a first valve 285 in the first inlet 220 and a second valve 290 located in the second inlet 225, and the tubular partition wall 235 is an inlet of a compressor housing 270 for a turbocharger (150, fig. 1).

Description

A DEVICE FOR CONNECTING AN EXHAUST GAS RECIRCULATION CONDUIT TO

AN INTAKE PIPE

TECHNICAL FIELD

The present invention relates to a device for fluidly connecting an exhaust gas recirculation (EGR) conduit to an intake pipe of an internal combustion engine, for example an internal combustion engine of a motor vehicle.

BACKGROUND

It is known that an internal combustion engine, such as a compression-ignition engine (e.g. Diesel engine) ora spark-ignition engine (e.g. gasoline engine), is conventionally equipped with an intake system provided for conveying comburent air into the engine cylinders, and with an exhaust system provided for discharging the exhaust gasses from the engine cyl-inders to the external environment.

The intake system generally comprises an intake pipe connecting an air filter to an intake manifold that distributes the incoming air into the engine cylinders. Likewise, the exhaust system generally comprises an exhaust manifold that collects the exhaust gasses coming from the engine cylinders and conveys them into an exhaust pipe leading to the external environment.

To increase the pressure of the comburent air entering the cylinders, the internal combus-tion engine may be equipped with a turbocharger having a turbine located in the exhaust pipe and a compressor mechanically coupled with the turbine and located in the intake pipe. The turbine is rotated by the exhaust gasses flowing towards the external environ- ment and causes the rotation of the compressor, which increases the pressure of the com-burent air into the intake pipe.

The internal combustion engine may be further equipped with an exhaust gas recirculation (EGR) system which is provided for recirculating a portion of the exhaust gasses from the exhaust system back into the intake system, basically in order to reduce nitrogen oxides gen oxides (NOr) emissions.

The EGR system may be either a "short-route" EGR system or "long-route" EGR system (also known as low pressure EGR system).

The "long route" EGR system basically comprises an EGR conduit that branches from the exhaust pipe downstream of the aftertreatment gas system (turbine) and leads the exhaust gasses into the intake pipe upstream of the compressor. The EGR system fur-ther comprises an EGR cooler located in the EGR conduit to reduce the temperature of the exhaust gasses before they reach the intake pipe, and an EGR valve located at the junction between the EGR conduit and the intake pipe, which is provided for regulating the amount of exhaust gasses that is recirculated into the intake system.

The EGR valve conventionally comprises an external housing shaped as a Tee having a first inlet coupled to the intake pipe, a second inlet coupled to the EGR conduit, and a single outlet coupled to a compressor inlet of the turbocharger. Within this Tee-shaped valve housing, the exhaust gasses coming from the EGR cooler are thus freely mixed with the comburent air coming from the intake pipe and deviated towards the compres-sor.

The exhaust gasses coming from the EGR cooler have usually a high water content and their temperature is higher than the temperature of the comburent air coming from the external environment and/or of the temperature of the valve housing and intake pipe.

During the warm-up phase of the internal combustion engine and/or in cold weather con-ditions, when this relatively hot and wet exhaust gas stream contact the colder walls of the intake pipe and mixes with the colder air stream within the valve housing, the vapor contained therein condenses.

The vapor condensation generates water droplets that are accelerated by the air stream and projected at high speed to collide with the compressor wheel, which can thus be damaged.

To prevent these damages, the EGR valve is conventionally controlled to minimize as much as possible the recirculation of the exhaust gasses in cold weather condition and/or during the engine warm-up phases. However, this solution represents an im-portant limitation to the efficiency of the EGR system, which contributes to increase the pollutant emissions of the engine.

SUMMARY

An object of an embodiment of the present invention is that of solving or at least of posi- tively reducing the above mentioned drawbacks linked with the condensation of the va-por contained in the recirculated exhaust gasses.

Another object is that of reach this goal with a simple, rational and rather inexpensive so-lution.

These and other objects are achieved by the embodiments of the invention having the features recited in the independent claims. The dependent claims delineate secondary aspects of the invention.

An embodiment of the invention provides a device for fluidly connecting an exhaust-gas-recirculation conduit to an intake pipe of an internal combustion engine, comprising an external housing having a first inlet for connection with the intake pipe and a second inlet for connection with the exhaust-gas-recirculation conduit, an inner volume of the external housing being divided by a tubular partition wall into a central conduit in fluid communica- tion with the first inlet and an annular chamber surrounding the central conduit and in flu- id communication with the second inlet, the tubular partition wall comprising at least a ra-dial opening through which the annular chamber is set in fluid communication with the central conduit.

Thanks to this solution, while passing through the annular chamber and the radial open-ing, the exhaust gasses coming from the EGR conduit are slowed down, so that their penetration within the air stream is reduced. The exhaust gasses that pass through the radial opening are immediately deviated and tend to adhere to the partition wall at the periphery of the central conduit, whereas the main air stream flows at the center. In this way, the device reduces the mixing between the comburent air and the exhaust gasses, thereby reducing also the condensation phenomena of the vapor contained in the ex-haust gasses. This device is thus able to reduce the risk of damaging the compressor wheel and gives the opportunity of effectively using the EGR system also during the en-gine warm-up and/or in cold weather conditions.

According to an aspect of the invention, the tubular partition wall may comprise a plurality of radial openings to set the annular chamber in fluid communication with the central conduit.

This solution reduces the pressure drop to which the exhaust gasses are subjected while passing from the annular chamber into the central conduit.

By way of example, the radial openings may be circumferentially distributed about a cen-tral axis of the tubular partition wall.

In this way, the stream of exhaust gasses entering the central conduit is made more uni-form.

According to another aspect of the invention, the tubular partition wall may be aligned (e.g. coaxial) with the first inlet.

This solution reduces the pressure drop to which the comburent air is subjected while passing through the central conduit.

According to another aspect of the invention, the second inlet axis is orthogonal to the first inlet axis.

In this way, the device may be easily connected to the intake pipe and to the EGR con-duit.

Another aspect of the invention provides that the tubular partition wall may realized as a separate part that is inserted into an opening of the external housing with the interposi-tion of a first gasket.

While the partition wall could also be realized in a single body with the external housing, this solution simplifies the manufacturing of the device.

According to another aspect of the invention, the tubular partition wall may be coupled to the first inlet by means of a second gasket.

In this way, the annular chamber is sealed between the first and second gaskets and communicates with the internal conduit exclusively through the radial hole(s), thereby improving its functionality.

Another aspect of the invention provides that the tubular partition wall may be an inlet of a compressor housing for a turbocharger.

Thanks to this solution, it results that the exhaust gasses are supplied into the air stream very close to the compressor wheel, for example not more than 1 cm upstream of the compressor wheel, thereby reducing the contact surface between the exhaust gasses and the walls of the device. At the same time, the heat produced by the air compression within the compression housing is quickly transmitted to the external housing of the de-vice, thereby increasing the temperature of the walls in contact with the exhaust gasses.

These concomitant effects concur to further reduce the condensation phenomena, there-by enhancing the achievements of the device.

According to another aspect of the invention, the device may comprise at least a valve member, for example a throttle body, located inside the external housing.

In this way, the device embodies an EGR valve capable of regulating the amount of ex-haust gasses that is recirculated into the intake system.

The valve member may be located in the first inlet to choke the incoming flow of combu-rent air.

In this case, the valve member has the effect of subjecting the air stream to a pressure drop, which in its turn affects the pressure level within the central conduit of the device and thus the quantity of exhaust gasses sucked from the EGR conduit. Therefore, by regulating the position of the valve member, it is possible to regulate the pressure level and so the exhaust gas quantity.

The valve member may be also located in the second inlet to choke the incoming flow of recirculated exhaust gas In this case, the valve member regulates directly the quantity of exhaust gasses coming from the EGR conduit.

According to an aspect of the invention, the device may particularly comprise both a first valve member located in the first inlet and a second valve member located in the second inlet.

In this way, the regulation of the exhaust gas content in the comburent air can be ex-tremely precise.

According to another aspect of the invention, the first and the second valve members may be coupled to a same motor.

This solution allows a reliable control of the two valve members, while reducing the man-ufacturing cost of the device.

Another embodiment of the invention provides an internal combustion engine equipped with an intake pipe, an exhaust pipe, a turbocharger having a compressor located in the intake pipe and a turbine located in the exhaust pipe, an exhaust-gas-recirculation con- duit branching from the exhaust pipe downstream of the turbine, and the above-described device having the first inlet connected to the air intake pipe upstream of the compressor and the second inlet connected to the exhaust-gas-recirculation conduit.

This embodiment of the invention achieves basically the same effects mentioned in con-nection with the device, particularly that of reducing the condensation phenomena of the vapor contained in the exhaust gasses, thereby protecting the compressor wheel from damages due to collisions with water droplets.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will now be described, by way of example1 with reference to the accompanying drawings.

Figure 1 is a schematic representation of an automotive system according to an embod-iment of the invention.

Figure 2 is the section Il-Il of figure 3 showing a connecting device included in the auto-motive system of figure 1.

Figure 3 is the section Ill-Ill of figure 2.

DETAILED DESCRIPTION

Some embodiments may include an automotive system 100, as shown in figure 1, which comprises an internal combustion engine 105, for example a Diesel engine of a motor vehicle.

The internal combustion engine 105 may be equipped with an air intake system compris-ing an air intake pipe 110 connecting an air inlet 115 to an intake manifold 120, which distributes the comburent air coming from the air inlet 115 into the engine cylinders. An air filter 125 may be located in the intake pipe 110, in order to remove solid particulates such as dust, pollen, mold, and bacteria from the comburent air.

The internal combustion engine 105 may be further equipped with an exhaust system comprising an exhaust manifold 130 provided for collecting the exhaust gasses exiting the engine cylinders, and an exhaust pipe 135 for conveying the exhaust gasses from the exhaust manifold 130 into the external environment.

To reduce the pollutant emission of the engine 105, the exhaust system may comprise one or more aftertreatment devices located in the exhaust pipe 135 and configured to change the composition of the exhaust gasses. By way of example, the aftertreatment devices may include a diesel oxidation catalyst (DOC) 140 for degrading residual hydro- carbons (HC) and carbon oxides (CO) contained in the exhaust gasses, and a diesel par-ticulate filter (DPF) 145 for capturing and removing diesel particulate matter (soot) from the exhaust gasses.

The internal combustion engine 105 may be also equipped with a turbocharger 150 pro-vided for boosting the pressure of the comburent air into the intake manifold 120, in order to improve the engine performance. The turbocharger 150 comprises a compressor 155 located in the intake pipe 110, downstream of the air filter 125. and rotationally coupled to a turbine 160 located in the exhaust pipe 135, between the exhaust manifold 130 and the aftertreatment devices. The turbine 160 has a wheel that rotates by receiving exhaust gasses from the exhaust manifold 130 that directs the exhaust gasses through a series of vanes prior to expansion through the turbine 160. The turbine 160 may be a variable geometry turbine (VGT) with a VGT actuator arranged to move the vanes to alter the flow of the exhaust gases through the turbine 160. In other embodiments, the turbine 160 may be fixed geometry and/or include a waste gate. The rotation of the turbine wheel draws in rotation the wheel 280 of the compressor 155 (see fig. 2), which increases the pressure and temperature of the comburent air in the intake pipe 110 and manifold 120.

An intercooler 165, also referred as Charge Air Cooler, may be disposed in the intake pipe 110 downstream of the compressor 155, to cool the air stream before it reaches the intake manifold 120.

In order to reduce the polluting emissions, particularly the nitrogen oxides (NO) emis- sions, the automotive system 100 may comprise an exhaust gas recirculation (EGR) sys-tem, in this example a "long-route" or low-pressure" EGR system, which is provided for recirculating a portion of the exhaust gasses from the exhaust system back into the in-take system and thus into the engine cylinders.

The EGR system basically comprises an EGR conduit 170, which fluidly connects the exhaust pipe 135 to the intake pipe 110, and an EGR cooler 175 located in the EGR conduit 170 to reduce the temperature of the recirculated exhaust gasses before they reach the intake pipe 110. More specifically, the EGR conduit 170 branches from a por-tion of the exhaust pipe 135 located downstream of the turbine 160, in the example downstream of the DPF 145, and meets a portion of the intake pipe 110 located between the air filter 125 and the compressor 155, particularly as close as possible to the com-pressor 155.

According to an aspect of the invention, the connection between the EGR conduit 170 and the intake pipe 110 may be achieved by means of a device 200 that is shown in de-tails in the figure 2 and 3.

The device 200 comprises an external housing 205 that may be made of metal, for ex- ample of steal or aluminum. The housing 205 may comprise a portion 210 shaped sub-stantially as a barrel having a central axis A and defining an inner volume 215. Coaxial with the barrel-shaped portion 210, the housing 205 comprises a first inlet hose 220, which is in fluid communication with the inner volume 215 and which may be realized in a single body with the barrel-shaped portion 210. The first inlet hose 220 is destined to be coupled to the intake pipe 110, thereby receiving the air stream coming from the air filter 125. The diameter of the first inlet hose 220 may be smaller than the diameter of the bar-rel-shaped portion 210.

The housing 205 may further comprise a second inlet hose 225, which projects from the lateral wall of the barrel-shaped portion 210 and is in fluid communication with the inner volume 215. The second inlet hose 225 is destined to be coupled to the EGR conduit 170, thereby receiving the exhaust gasses coming from the EGR cooler 175. The second inlet hose 225 is designed so that its central axis B is set at right angle to the axis A of the first inlet hose 220, for example coplanar with the latter. Also the second inlet hose 225 may be realized in a single body with the barrel-shaped portion 210 and possibly with the first inlet hose 220.

Opposite to the first inlet hose 220, the housing 205 may comprise a through hole 230 and a tubular partition wall 235 which is inserted into the through hole 230 to extend with-in the inner volume 215, for example coaxially aligned with barrel-shaped portion 210. An annular gasket 240, such as an 0-ring, may be interposed between the tubular partition wall 235 and the internal edge of the through hole 230 to seal the inner volume 215. The diameter of the tubular partition wall 235 is smaller than the diameter of the barrel-shaped portion 210, for example almost equal to the diameter of the first inlet hose 220, and the length may be so that the tubular partition wall 235 extends into the inner volume 215 for the entire length of the barrel-shaped portion 210. For example, the free end of the tubular partition wall 235 may abut against a corresponding seat 245 realized at the end of the first inlet hose 220, to realize a mutual connection. A second annular gasket 250, such as an 0-ring, may be interposed between the free end of the tubular partition wall 235 and the corresponding seat 245, to seal the connection between the tubular par-tition wall 235 and the first inlet hose 220. a

In this way, the tubular partition wall 235 divides the inner volume 215 of the barrel-shaped portion 210 into a central conduit 255 in fluid communication with the first inlet hose 220 and an annular chamber 260 surrounding the central conduit 255 and in fluid communication with the second inlet hose 225.

The annular chamber 260 is in fluid communication with the central conduit 255 through a plurality of radial openings 265 realized in the tubular partition wall 235, particularly in the portion comprised between the first and the second annular gasket 240 and 250. By way of example, these radial openings 265 may be circumferentially distributed about the central axis A of the tubular partition wall 235, for instance angularly equidistant from one another.

The tubular partition wall 235 may be made of metallic material, such as of steal or alu-minum, and is destined to be set in fluid communication with an inlet duct of an housing 270 of the compressor 155. In particular, the coupling between the tubular partition wall 235 and the compressor inlet duct may be arranged so that the distance between the ra-dial openings 265 and the compressor wheel 280 (along the axis A) results as small as possible, for example not larger than 1 cm.

By way of example, the tubular partition wall 235 may be itself the inlet duct of the com-pressor housing 270. In other words, the tubular partition wall 235 may be realized in a single body with a metallic volute 275 of the housing 270 that encloses the compressor wheel 280.

Thanks to the device 200, the exhaust gasses coming from the EGR conduit 170 enters from the second inlet hose 225 into the annular chamber 260, thereby slowing down.

From the annular chamber 260, the exhaust gasses then pass through the radial open-ings 265 into the central conduit 255. Since their speed is relatively small, the exhaust gasses are immediately deviated towards the compressor 155, without deep penetrating in the air stream flowing at the center of the central conduit 255. In this way, the device reduces the mixing degree between the comburent air and the exhaust gasses, thereby reducing the water condensation phenomena that may occur during the warm-up of the engine 105 and/or under cold weather conditions.

This effect is enhanced also by the extreme vicinity between the radial openings 265 and the compressor wheel 280, which reduces the contact surface between the exhaust gas-ses and the tubular partition wall 235, and which allows the heat produced by the air compression within the compressor housing 270 to be quickly transmitted to the device 200, thereby increasing fast the temperature of the tubular partition wall 235 that is in di-red contact with the exhaust gasses.

According to some embodiments, the device 200 may be particularly embodied as an EGR valve, which not only connects the EGR conduit 170 and the intake pipe 110 but is also capable of regulating the amount of exhaust gasses that is recirculated and mixed with the air stream.

For this reason, the device 200 may further comprise a first valve member 285, for ex-ample a throttle body, located in the first inlet hose 220 to choke the air stream coming from the air filter 125. This first valve member 285 has the effect of subjecting the air stream to a pressure drop, which reduces the pressure level within the central conduit 255 and thus increases the quantity of exhaust gasses sucked from the EGR conduit 170. Therefore, by regulating the position of the first valve member 285, it is possible to regulate the exhaust gas quantity.

The exhaust gas quantity may be regulated also by a second valve member 290, for ex- ample another throttle body, located in the second inlet hose 220 to directly choke the in-coming stream of recirculated exhaust gas.

These two valve members 285 and 290 may be actuated by a single motor 295, for ex-ample a DC motor, which is coupled to both of them by means of suitable leverages or other mechanical transmissions. This motor 295 may be in its turn connected to an elec-tronic control unit (ECU) 300, which is configured to move the valve members 285 and 290 according to predetermined strategies.

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 examples, and are not intended to limit the scope, applicability, or configuration in any way. Rather, the foregoing summary and detailed description 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 arrangement of elements described in an exemplary embodiment without departing from the scope as set forth in the appended claims and their legal equivalents.

REFERENCES

automotive system internal combustion engine 110 intake pipe airinlet intake manifold airfilter exhaust manifold 135 exhaust pipe diesel oxidation catalyst diesel particulate filter turbocharger compressor 160 turbine intercooler EGR conduit EGR cooler device 205 housing 210 barrel-shaped portion 215 inner volume 220 first inlet hose 225 second inlet hose 230 through hole 235 tubular partition wall 240 annular gasket 245 seat 250 annular gasket 255 central conduit 260 annular chamber 265 radial openings 270 compressor housing 275 volute 280 compressor wheel 285 first valve member 290 second valve member 295 motor 300 electronic control unit A axis B axis

Claims

CLAIMS1. A device (200) for fluidly connecting an exhaust-gas-recirculation conduit (170) to an intake pipe (110) of an internal combustion engine (105), comprising an external housing (205) having a first inlet (220) for connection with the intake pipe (110) and a second inlet (225) for connection with the exhaust-gas-recirculation conduit (170), an in-ner volume (215) of the external housing (205) being divided by a tubular partition wall (235) into a central conduit (255) in fluid communication with the first inlet (220) and an annular chamber (260) surrounding the central conduit (255) and in fluid communication with the second inlet (225), the tubular partition wall (235) comprising a radial opening (265) through which the annular chamber (260) is set in fluid communication with the central conduit (255).
2. A device (200) according to claim 1, wherein the tubular partition wall (235) com- prises plurality of radial openings (265) to set the annular chamber (260) in fluid commu-nication with the central conduit (255).
3. A device (200) according to claim 2, wherein the radial openings (265) are circum-ferentially distributed about a central axis (A) of the tubular partition wall (235).
4. A device (200) according to any of the preceding claims, wherein the tubular parti-tion wall (235) is aligned with the first inlet (220).
5. A device (200) according to any of the preceding claims, wherein the second inlet axis (B) is orthogonal to the first inlet axis (A).
6. A device (200) according to any of the preceding claims, wherein the tubular parti-tion wall (235) is realized as a separate part that is inserted into an opening (230) of the external housing (205) with the interposition of a first gasket (240).
7. A device (200) according to claim 6, wherein the tubular partition wall (235) is cou-pled to the first inlet (220) by means of a second gasket (250).
8. A device (200) according to any of the preceding claims, wherein the tubular parti-tion wall (235) is an inlet of a compressor housing (270) for a turbocharger (150).
9. A device (200) according to any of the preceding claims, comprising a valve mem-ber (285, 290) located inside the external housing (205).
10. A device (200) according to claim 9, wherein the valve member (285) is located in the first inlet (220) to choke the incoming flow of comburent air.
11. A device (200) according to claim 9, wherein the valve member (290) is located in the second inlet (225) to choke the incoming flow of recirculated exhaust gas.
12. A device (200) according to claim 9, comprising a first valve member (285) located in the first inlet (220) and a second valve member (290) located in the second inlet (225).
13. A device (200) according to claim 12, wherein the first and the second valve mem-bers (285, 290) may be coupled to a same motor (295).
14. An internal combustion engine (105) equipped with an intake pipe (110), an ex-haust pipe (135), a turbocharger (150) having a compressor (155) located in the intake pipe (110) and a turbine (160) located in the exhaust pipe (135), an exhaust-gas- recirculation conduit (170) branching from the exhaust pipe (135) downstream of the tur-bine (160), and a device (200) according to any of the preceding claims having the first inlet (220) connected to the air intake pipe (110) upstream of the compressor (155) and the second inlet (225) connected to the exhaust-gas-recirculation conduit (170).