EP2737187A1

EP2737187A1 - Exhaust device and vehicle comprising such an exhaust device

Info

Publication number: EP2737187A1
Application number: EP11791044.8A
Authority: EP
Inventors: Patrick Berthon; Philippe ESTOR
Original assignee: Renault Trucks SAS
Current assignee: Volvo Truck Corp
Priority date: 2011-07-29
Filing date: 2011-07-29
Publication date: 2014-06-04
Anticipated expiration: 2031-07-29
Also published as: WO2013017908A1; EP2737187B1; JP5978300B2; JP2014521863A

Abstract

The exhaust device (1 ) comprises: a gas outlet (3) for releasing into the atmosphere, the gas outlet being substantially shaped as a slot; a downstream wall (13) along the gas outlet (3), the downstream wall (13) being arranged with respect to the upstream wall (12) so that the exhaust gases flow out of the gas outlet (3) tangentially to the downstream wall (13); wherein the distance between the downstream wall (13) and a plane tangent (P13) to the downstream wall 13 at the gas outlet (3) generally increases with the distance from the gas outlet (3).

Description

EXHAUST DEVICE AND VEHICLE COMPRISING SUCH AN EXHAUST

DEVICE

Field of the invention

The present invention relates to an exhaust device, for a vehicle of the type having an internal combustion engine and an exhaust system, in particular of the type comprising a Diesel particulate filter and/or a selective catalytic reduction component. Besides, the present invention relates to a vehicle comprising such an exhaust device.

Technological background

The exhaust gases formed during the combustion of fuel in an internal combustion engine, in particular in industrial vehicles, may contain a proportion of undesirable components such as nitrogen oxides (NOx), carbon monoxide (CO), un-burnt hydrocarbons (HC), soot, etc...

To reduce air pollution, the exhaust system of a vehicle is usually equipped with an exhaust after-treatment system which deals with undesirable substances in exhaust gases.

One type of exhaust after-treatment system comprises a diesel particulate filter and/or a selective catalytic reduction component which removes un-burnt particles contained in the exhaust gases. A diesel particulate filter and/or a selective catalytic reduction component may eventually become clogged by the un-reacted particles and needs to be regenerated from time to time.

One way of regenerating the diesel particulate filter and/or a selective catalytic reduction component is to increase the exhaust gases temperature up to a regenerating temperature where the particles trapped in the diesel particulate filter and/or a in a selective catalytic reduction component are oxidized, for instance beyond 600°Celsius.

In some cases, the driver is compelled to stop the vehicle during the regeneration process. This may be the case in particular for a vehicle working in "start-and-stop" cycles, like refuse collecting trucks or buses, the regeneration process being then carried out at standstill, because its internal combustion engine cannot reach the regenerating temperature.

However, especially whe n ca rri ed o ut at standstill, this regeneration process can prove dangerous for the vehicle or for its environment. Indeed, the exhaust pipe, which is located at the downstream end of the exhaust system, usually expels a hot, pointed gas flow, say at 200°Celsius over a distance of about 1200 mm. Hence, the vehicle and/or any element located within reach of this pointed gas flow is exposed to a hot temperature. Eventually, some elements may even be set on fire by this hot, pointed gas flow.

E P 1 071 868A1 d iscloses a prior art exhaust device which comprises a gas discharge in the form of a slot for releasing the exhaust gases into the atmosphere. The discharge slot extends perpendicular to the direction of travel of the vehicle. When the vehicle is moving, the exhaust gases released by the outlet slot are diluted by the air slipstream. Thus, the temperature of the exhaust gas flow decreases over a given distance.

Yet, this given distance can be insufficient to avoid any risk for the vehicle and/or its environment caused by the hot exhaust gases. In particular, when the vehicle is at standstill or moving too slow to generate the air slipstream, the exhaust device of EP1071868A1 still releases hot and undiluted exhaust gases.

It therefore appears that, from several standpoints, there is room for improvement in the exhaust systems of vehicles. Summary

It is an object of the present invention to provide an exhaust device which can efficiently decrease the temperature of exhaust gases from an exhaust after-treatment system.

Another object of the invention is to provide an exhaust device wh ich ca n m ix the exh a ust gases released i nto the atmosphere with surrounding air, in particular when the vehicle is at standstill, without moving or moving slowly. A subject-matter of the invention is an exhaust device, for a vehicle of the type having an internal combustion engine and an exhaust system, the exhaust device comprising at least:

a gas outlet suitable for releasing exhaust gases into the atmosphere, the gas outlet being substantially shaped as a slot;

a downstream wall extending downstream of the gas outlet and along most or all of the length of said gas outlet, the downstream wall having an outer surface arranged to be in contact with the exhaust gases flowing out of the gas outlet,

wherei n the gas outlet the downstream wall are arranged respectively so that the exhaust gases flow out of the gas outlet substantially tangentially to the downstream wall;

and wherein the distance between the downstream wall and a plane tangent to the downstream wall at the gas outlet generally increases with the distance from the gas outlet.

In the present application, the terms "upstream" and "downstream" relate to the flow of exhaust gases which flow from the gas inlet to the gas outlet. In the present application, the terms "inner" and "outer" relate to the volume of the main chamber, i.e. to the volume of the exhaust device.

In the present application, the term "overall" as applied to inlet and outlet perimeters and areas implies that the whole perimeter or area is to be considered for one gas outlet. For instance, the gas outlet can be divided into several adjacent openings, or even into a plurality of holes. In such a case, the overall outlet area corresponds to the sum of all individual areas of every opening or hole.

In an embodiment, the downstream wall can form a generally convex outer surface.

The convexity or curvature may somewhat vary along the longest dimension of the gas outlet.

In another embodiment, the downstream wall can have a generally plane outer surface.

An alternative embodiment of the invention is an exhaust device, for a vehicle of the type having an internal combustion engine and an exhaust system, the exhaust device comprising at least: a gas outlet suitable for releasing exhaust gases into the atmosphere, the gas outlet being substantially shaped as a slot;

a downstream wall extending downstream of the gas outlet and along most or all of the length of the gas outlet, the downstream wall having an outer surface arranged to be in contact with the exhaust gases flowing out of the gas outlet

wherein the gas outlet and the downstream wall are arranged respectively so that the exhaust gases flow out of the gas outlet substantially tangentially to the downstream wall;

and wherein the exhaust device further comprising an inner wall extending upstream of the gas outlet and opposite a downstream portion of the downstream wall so as to define at least one intermediate chamber where the flow of exhaust gases is directed substantially tangentially to the downstream wall.

In the present application, the term "substantially tangentially" applies to a tangent direction plus all directions forming a low angle with a tangential direction, i.e. all directions forming a angle lying within a range of plus or min us 30 degrees. Besides, the term "substantially tangentially" applies locally, along all or part of the downstream wall. In other words, the term "substantially tangentially" can apply:

either to an invariable direction, in case the outer surface of the downstream wall has a great radius of curvature, e.g. an infinite radius of curvature, viz. the outer surface is plane;

or to a direction that varies smoothly along all or part of the downstream wall.

In the present application, the term "length" refers to the longest dimension of an element, e.g. of the gas outlet. The gas outlet has the general shape of a slot, since it has a relatively high ratio of outlet perimeter over outlet area.

An exhaust device according to the invention improves the cooling and dilution of the exhaust gases released into the atmosphere. Indeed, the flow of exhaust gases, out of a slot-like gas outlet, enables entrainment of air surrounding the upstream wall. The entrained air flow rate is about twice as much as the gas flow rate out of a gas outlet, or even more. This entrainment results from the fact that the flow of exhaust gases is released substantially tangentially to the downstream wall, thus avoiding or minimizing the separation of this flow from the downstream wall. Depending on the service conditions, such a flow of exhaust gases can generate some Venturi effect and/or some Coanda effect, hence entrain a flow of surrounding air for diluting and cooling exhaust gases.

In other words, the specific arrangement of the downstream wall, the upstream wall and the gas outlet can promote Coanda effect and/or Venturi effect. The entrainment of air by the Coanda effect can occur during the regeneration process and when the vehicle is at standstill.

The higher outlet ratio enhances the flow rate of air intake or air suction, hence the cooling and mixing of exhaust gases. Indeed, the contact surface between air and gas is maximized.

Even in cases where the exhaust gases enter the exhaust device at nearly 600°C, the temperature of the resulting gas and air mixed flow can be as low as 200°Celsius at only 100 mm away from the outlet, thus avoiding the risks and dangers for persons or elements standing close to a vehicle according to the invention at standstill, during a regeneration process.

Moreover, the operation of an exhaust device according to the invention is reliable.

These and other features and advantages will become apparent upon reading the following description in view of the drawings appended thereto, which represent, as non-limiting examples, embodiments of an exhaust device according to the invention.

Brief description of the drawings

The following detailed description of several embodiments of the invention is better understood when read in conjunction with the appended drawings. However, the invention is not limited to the specific embodiments disclosed herewith.

Figure 1 is a schematic, perspective view of an exhaust device according to a first embodiment of the invention;

Figure 2 is a gas flow computer model of the pathlines of the gases flowing in and out of the exhaust device of figure 1 ; Figure 3 is a cross section taken along plane III at figure 2;

Figure 4 is a schematic cross section of the exhaust device of figure 1 ;

Fig u re 5 is a view si m ilar to fig ure 4 of an exhaust device according to a second embodiment of the invention;

Fig u re 6 i s a view si m il ar to fig ure 4 of an exhaust device according to a third embodiment of the invention;

Fig ure 7 is a view si m i lar to fig ure 4 of an exhaust device according to a fourth embodiment of the invention;

Fig u re 8 is a view similar to fig ure 4 of an exhaust device according to a fifth embodiment of the invention;

Fig u re 9 is a view si mila r to fig u re 4 of an exhaust device according to a sixth embodiment of the invention;

Fig ure 1 0 is a schematic cross section of an exhaust device according to a seventh embodiment of the invention;

Figure 1 1 is a perspective view of an exhaust device according to an eighth embodiment of the invention;

Figure 12 is a translucent, perspective view, at a different angle, of the exhaust device of figure 1 1 ;

Figure 13 is a perspective view, taken along arrow XIII at figure 1 , of the exhaust device of figure 1 1 ;

F i g u re 1 4 i s a gas flow computer model on a truncated perspective view of an exhaust device according to a ninth embodiment of the invention;

Figure 15 is a computer model on a truncated perspective view, taken along arrow XV at figure 14, of the exhaust device of figure 14;

Figure 16 is an enlarged view of detail XVI at figure 15;

Figure 17 is a view similar to figure 14 of an exhaust device according to an tenth embodiment of the invention;;

Figure 18 is a cross section taken along plane XVIII at figure 17;

Figure 19 is a schematic cross section of a vehicle according to an embodiment of the invention and having an exhaust system comprising an exhaust device according to the invention, the exhaust system being in a first state; Figure 20 is a view similar to figure 19 of the vehicle of figure 18, the exhaust system being in a second state;

Figure 21 is a schematic cross section of a vehicle according to another embodiment of the invention and having an exhaust system comprising an exhaust device according to the invention, the exhaust system being in a first state; and

Figure 22 is a view similar to figure 21 of the vehicle of figure 20, the exhaust system being in a second state. Detailed description of the invention

Figures 1 , 2, 3 and 4 illustrate an exhaust device 1 according to a first embodiment of the invention. The exhaust device 1 is intended for a vehicle of the type having an internal combustion engine and an exhaust system, in particular of the type comprising a Diesel particulate filter and/or a selective catalytic reduction component.

The exhaust device 1 comprises a gas inlet 2 which is suitable for connection to a not shown exhaust pipe and by way of a not shown connection means. Gas inlet 2 overall defines an inlet perimeter P2 and an inlet area A2, when taken in section along a plane perpendicular to the exhaust flow through the gas inlet 2.

Gas inlet 2 corresponds to the overall inlet flow path where exhaust gases enter exhaust device 1 , the gas inlet 2 be either formed as one unique opening or as several parallel openings. At figure 1 , arrows F2 represent the flow of exhaust gases entering gas inlet 2..

Gas inlet 2 can have the circular shape of a disc. Hence, inlet perimeter P2 and inlet area A2 depend on inlet diameter D2, which is for example comprised within 40 to 160 mm. An exemplary embodiment has an inlet of 100 mm diameter. The inlet ratio of inlet perimeter P2 over inlet area A2 can be defined by the formula R2=P2/A2 which, in the case of disc shaped inlet can be written R2=4/D. With the figures above, expressed in millimetres, the ratio may range between about 0.025 and 0.1

Furthermore, the exhaust device 1 can comprise a gas outlet 3 which is suitable for releasing exhaust gases into the atmosphere. At figure 1 , arrows F3 represent the flow of exhaust gases released out of gas outlet 3. The gas outlet 3 overall defines an outlet perimeter P3 and an outlet area A3.

The gas outlet 3 substantially has the shape of a slot. At the gas outlet 3, the exhaust gases flowing out of the exhaust device 1 come into contact with outside air. The gas outlet 3 can be defined as the surface of mi nimal size thro ug h which the gas may exit the exhaust device 1 . This surface can be planar, but it can also be a curved surface extending in three dimensions.

The gas outlet 3 overall defines an outlet perimeter P3 and an outlet area A3, when taken in section along a plane perpendicular to the exhaust flow through the gas outlet 3

Being in the shape of a slot means that it has a main dimension which is substantially greater that it other dimensions

I n the em bodiment of figures 1 to 3, gas outlet 3 is elongated along a straight line, perpendicular to the flow F3. Alternatively, the gas outlet cou ld be el o ng ated a l o ng a cu rved l i n e i n l i e u of a stra i g ht on e . Th e elong atio n l i ne cou ld even be three-dimensional. Along th is l i ne can be defined a length of the gas outlet. Perpendicularly to this line can be defined a width of the gas outlet.

The gas outlet 3 can have the shape of an oblong rectangle extending in a plane. In such a case, outlet perimeter P3 corresponds to the cumulated lengths of all four sides of the rectangle, i .e. of two long sides having length L3 and two thin sides having width H3. Outlet area A3 depends on outlet width H3 and on outlet length L3.

An exemplary embodiment, suitable for a truck mounted exhaust device, has an outlet having a length comprises between 400 mm and 1 500 mm, for example 600 mm, and a width H3 of about 2 to 8 mm, for example 3 mm. The outlet ratio R3 of outlet peri meter P3 over outlet a rea A3 can therefore range from about 0.25 to 0.66 when expressed in mm . The outlet ratio is high, and in particular substantially greater than the inlet ratio.

In absolute terms, it can be considered that the gas outlet has the s ha pe of a sl ot where its length is at least 15 ti mes its width, and preferably at least 50 times its width. In some applications, the ratio of length to width can exceed 200. According to another definition, it can be considered that the outlet has the shape of a slot if the outlet ratio of outlet perimeter P3 over outlet area A3 exceeds 0.2, expressed in mm.

According to another definition of the shape of the slot, the gas outlet can be defined trough the adimensional ratio R'3=(P3)²/A3. For the outlet to be qualified as a slot, the adimensional ratio is preferably over 50, and more preferably over 200.

The exhaust device 1 can further comprise a main chamber 4 located on the flowpath between the gas inlet 2 and the gas outlet 3. In this embodiment, the gas outlet 3 is the sole outlet from the main chamber 4.

Main chamber 4 is connected to a pipe section 5 at a connexion section 4.5. Pipe section 5 is in the form of a cylinder with an axis Y and with a circular basis formed by gas inlet 2. On figures 1 to 3, pipe section 5 defines the gas inlet 2, the inlet area A2 and the inlet perimeter P2. Connexion section 4.5 approximately has the same area and perimeter than the gas inlet 2.

The main chamber 4 channels exhaust gases from connexion section 4.5 to the gas outlet 3. In this embodiment, main chamber 4 is in the form of a cylinder so that it is delimited by peripheral wall which comprise a mostly cylindrical wall with an axis substantially parallel to axis Y and with a basis having an aircraft wing profile.

As illustrated at figure 3, this aircraft wing profile has a leading edge 3.1 and a trailing edge 3.2. In the example of figures 1 to 3, the main chamber 4 has an obstructed end located opposite the pipe section 5 along axis Y to its cylindrical wall.

In this embodiment, the gas outlet 3 is arranged directly in the peripheral wall of the main chamber 4, more precisely in the cylindrical wall. On the other hand, the gas inlet 2 is arranged in an end wall of the main chamber 4, said end wall being essentially perpendicular to axis Y. As a conseq uence , the flow F3 throug h the gas outlet 3 is su bstantia l ly perpendicular to the flow F2 through the gas inlet 2 and the connection section 4.5.

The gas outlet 3 defines in the peripheral wall a downstream wall 13 and an upstream wall 12. Expressed differently, the upstream 12 and downstream 13 walls define between them the gas outlet 3. Indeed, in this embodiment, in the vicinity of gas outlet 3, the upstream 12 and downstream 13 walls can extend in two planar regions which are substantially parallel, i.e. forming an angle of less than 30 degrees, but which are offset along a direction X3 perpendicular to those planar regions.

The upstream wall 12 is located towards the exterior of main chamber 4 as compared to the downstream wall 13. In this embodiment, the offset between those planar regions extends along a radial direction which is perpendicular to an axis Y. Due to this offset, the flow F3 through gas outlet 3 will not be perpendicular to the planar regions of the upstream 12 and downstream 1 3 walls, but rather parallel to at least one of those planar regions. Therefore, their respective "upstream" and "downstream" denominations refer to their respective locations with respect to the flow F3.

The downstream wall 13 and the gas outlet 3 are respectively arranged so that the exhaust gases flow out of gas outlet 3 substantially tangentially to the downstream wall 13.

The exhaust device 1 thereby comprises a downstream wall 13 extending downstream of the gas outlet 3 and, parallel to axis Y, along all or most of the length L3 of gas outlet 3.. The downstream wall 13 has an outer surface 13.4 arranged to be in contact with the flow F3 exhausted through gas outlet 3.

Accord ing to the invention, the distance between the downstream wall 13 and a plane P13 tangent to the downstream wall 13 at the gas outlet 3 generally increases with the distance from the gas outlet 3, along plane P13.

In particular, the downstream wall 1 3 can form a generally convex outer surface. In the example of figures 1 to 3, the whole outer surface of the downstream wall 13 is convex. The outer surface of the downstream wall 13 has a curved cross-section that extends from gas outlet 3 to the trailing edge 3.2 of the aircraft wing profile of the main chamber 4.

In other words, the downstream wall 13 is arranged with respect to the gas outlet 3 so as to diverge from the exhaust direction D3 of the exhaust gases out of the gas outlet 3.

In other words, the downstream wall 13 ant the gas outlet 3 are respectively arranged with respect one to the other so that, at the gas outlet 3, the exhaust gases flow out of gas outlet 3 along a direction D3 substantially tangential to the downstream wall 13, and so that the downstream wall 13 then diverges from the exhaust direction D3 as defined at the gas outlet 3. The divergence can be continuous or discontinuous, e.g. by steps.

Preferably, the respective dimensions and orientations of the surface are such that, at least for specified operating conditions (e.g. filter regeneration at standstill), the flow F3 of exhaust gases tends to follow the downstream wall 13, thereby deviating from its initial direction D3 right at the gas outlet 3

The cylindrical wall can thereby comprise an upstream wall 12 extending on an upstream side of the flow F3 through gas outlet 3. Upstream wall 12 extends, parallel to axis Y, along all of the length L3 of gas outlet 3. The upstream wall 12 has an inner surface 12.4 arranged to be in contact with the flow F3 exhausted through gas outlet 3.

The upstream wall 1 2 extends in a volume which is located opposite the downstream wall 13 with respect to the plane P13 tangent to the downstream wall 13 at the gas outlet 3.

I n other words, upstream wall 12 and downstream wall 13 respectively define two elongated, opposite edges of gas outlet 3.

Exhaust device 1 can be arranged on the vehicle so that axis Y of main chamber 4 extends essentially parallel to forward running direction of the vehicle equipped thereof. I ndeed , the exhaust device is intended to perform its function of exhaust gas dilution especially when the vehicle is at standstill, i.e. when there is no significant natural flow of ambient air around the exhaust device, as compared to when the vehicle is driving at a certain speed.

Alternatively, axis Y can nevertheless be arranged at 90 degrees with respect to said forward running direction, for instance being essentially horizontal or essentially vertical.

In service, as illustrated at figures 1 and 2, gas flow F2, which is at a hot temperature of say 600°Celsius, enters the exhaust device 1 through pipe section 5 of the main chamber 4, where the gas flow F2 mainly flows parallel to axis Y.

On figure 2, the pathlines in full lines represent relatively hot gases, i.e. gases entering the exhaust device 1 , whereas the pathlines in dotted lines represent relatively cool gases, i.e. gases released out of exhaust device 1. Upstream air flow is not represented by pathlines at figure 2.

Then, the exhaust gases flow through the main chamber 4 of the main chamber 4 towards the gas outlet 3. The main chamber 4 thus guides the exhaust gases from gas inlet 2 to gas outlet 3.

Afterwards, the exhaust gases are released out of gas outlet 3 as gas flow F3. The gas flow F3 enables entrainment of an air flow F12 surrounding upstream wall 12. Thus, downstream the trailing edge 3.2, the total flow F3.2 corresponds to the sum of gas flow F3 plus air flow F12. Therefore, exhaust device 1 improves the cooling and dilution of the exhaust gases released into the atmosphere.

The entrainment of air flow F12 can result from Coanda effect. It may also result from Venturi effect, depending on the baffle location and geometry.

As illustrated on figures 3 and 4, the exhaust device 1 can further comprise an inner wall 14 extending inside the main chamber 4 and upstream of the gas outlet 3 and opposite an inner surface 12.4 of a downstream portion 12.1 of the upstream wall 12.

Preferably, the inner wall 14 lies in the continuation of downstream wall 13, such that the plane P13 tangent to the downstream wall

13 at the gas outlet 3 is also tangent to the inner wall 14 at the gas outlet 3, where the inner wall 14 and the downstream wall 13 join.

The inner wall 14 thus defines with the inner surface 12.4 of the upstream wall 12 an intermediate chamber 15 which is arranged to channel the flow of exhaust gases substantially tangentially to the plane P13 tangential to the downstream wall 13 at the gas outlet 3.

In other words, the inner wall 14 and the inner surface 12.4 of the upstream wall 12 determine the direction of the flow of exhaust gases F3 at the gas outlet 3.

Thus, the intermediate chamber 15 also enables entrainment of air flow F12 by properly orienting gas flow F3 at the gas outlet 3.

A length of the intermediate chamber 15, considered along the exhaust direction D3, is about 20 times the width H3 which represents the smallest dimension among the main dimensions generally defining the outlet perimeter P3. Preferably, the length of the intermediate chamber 15 lies between 1 and 50 times the width H3, more preferably over 10 times the width H3. Such a length of the intermediate chamber 15 enhances the entrainment of air flow F12, because it ensures a more uniform tangential orientation of gas flow F3.

In a preferred embodiment, the intermediate chamber 15 defines a convergent flowpath for the exhaust gases, i.e. so that the available cross section for the flow in the intermediate chamber 15 decreases towards the gas outlet 3. Thus, the exhaust gases are accelerated within the intermediate chamber 15, which also enhances the entrainment of air flow F12.

I n the example of fig ures 1 to 4 , the downstream wall 13 prolongs the inner wall 14. In fact, inner wall 14 is integral with downstream wall 13. Thus, there is a smooth transition between inner wall 14 and downstream wall 13, which prevents flow separation at the gas outlet 3.

The exhaust device 1 can also comprise one solid baffle 16 located away from the main chamber 4. As illustrated on figure 3, baffle 16 is arranged externally to the main chamber 4 and substantially parallel to the cylindrical wall of main chamber 4, in the vicinity of the gas outlet 3. The baffle 16 is thereby offset from both the upstream wall 12 and the downstream wall 13 by a certain distance along a direction perpendicular to the cylindrical wall.

Preferably, such a baffle can define a convergent flowpath between the baffle 16 and an outer surface of upstream wall 12. Baffle 16 may thus increase the fluid velocity of gas flow F3 and of air flow F12, hence the entrainment rate of air flow F12.

Alternatively, the baffle could extend opposite the downstream wall so as to form a divergent flowpath. Besides, baffle 16 forms a heat shield for protecting surrounding components of the vehicle and may also act as a noise shield if made of or covered by a noise absorbing or reflecting material.

Figure 5 illustrates an exhaust device 201 according to a second embodiment of the invention. The description of exhaust device 1 given above with reference to figures 1 to 4 can be transposed to exhaust device 201 and of figure 5, which is similar thereto, with the noticeable exception of the hereafter stated difference(s). An element of exhaust device 201 that has a structure or function similar or corresponding to that of an element of exhaust device 1 is given the same reference numeral plus 200. One can thus define exhaust device 201 , a gas inlet 202, a gas outlet 203, a m a i n chamber 204 , an u pstrea m wall 21 2 , a downstream wall 21 3, an inner wall 214 and an intermediate chamber 215.

Exha ust device 201 mainly differs from exhaust device 1 , because it i s free from any baffle. Thus, exhaust device 201 is relatively com pact a nd can be mou nted on veh i cles having only a s mall available space.

Figure 6 illustrates an exhaust device 301 according to a third embodiment of the invention . The description of exhaust device 201 given above with reference to figure 5 can be transposed to exhaust device 301 of figure 6, which is similar thereto, with the noticeable exception of the hereafter stated difference(s). An element of exhaust device 301 that has a structure or function similar or corresponding to that of an element of exhaust device 201 is given the same reference numeral plus 1 00.

One can thus define exhaust device 301 , a gas inlet 302, a gas outlet 303, a main chamber 304, an upstream wall 31 2 and a downstream wall 313.

Exhaust device 301 mainly differs from exhaust device 201 , because exhaust device 301 does not have any intermediate chamber nor any inner wall extending into the main chamber 304.

Th us, the exhaust device 301 is relatively light a nd easy to manufacture.

Figure 7 illustrates an exhaust device 401 according to a fourth embodiment of the invention. The description of exhaust device 1 given above with reference to figures 1 to 4 can be transposed to exhaust device 401 of figure 7, which is similar thereto, with the noticeable exception of the hereafter stated difference(s). An element of exhaust device 401 that has a structure or function similar or corresponding to that of an element of exhaust device 1 is given the same reference numeral plus 400.

One can thus define exhaust device 401 , a gas inlet 402, a gas outlet 403, a mai n chamber 404 , an upstream wall 41 2 , a downstream wall 41 3, an inner wall 414 and an intermediate chamber 415.

Exhaust device 401 mainly differs from exhaust device 1 , because exhaust device 401 comprises several baffles 416.1 , 416.2 and 416.3, which are arranged so as to be offset along a direction parallel to the flow F3, but substantially parallel to one another. The baffles are nevertheless preferably curved or angled between them, as exemplified on figure 7, so as to define between them successive convergent flow paths. Baffles 41 6.1 , 416.2 and 416.3 increase the rate of air flow entrained in by gas flow released out of gas outlet 403.

Fig ure 8 illustrates an exhaust device 501 accord ing to a fifth embodiment of the invention . The description of exhaust device 201 given above with reference to figure 5 can be transposed to exhaust device 501 of figure 8, which is similar thereto, with the noticeable exception of the hereafter stated difference(s). An element of exhaust device 501 that has a structure or function similar or corresponding to that of an element of exhaust device 201 is given the same reference numeral plus 300.

One can thus define exhaust device 501 , a gas inlet 502, a gas outlet 503, a trailing edge 503.2, a main chamber 504, an upstream wall 512, a downstream wall 51 3, an inner wall 514 and an intermediate chamber 515.

Exhaust device 501 mainly differs from exhaust device 201 , because exhaust device 501 comprises a second gas outlet 503B, a second upstream wall 51 2B, a second downstream wall 513B, a second inner wall 514B and a second intermediate chamber 515B. First and second gas outlets 503 and 503B are arranged so that the exhaust gases flow out of each of first and second gas outlets 503 and 503B in two different directions which are substantially tangential to a respective downstream wall 51 3 or 51 3B. These two directions are substantially convergent in the region of the trailing edge 503.2.

In this particular embodiment, the two gas outlets are arranged symmetrically with respect to a plane which contains a central axis of the main chamber.

Thus, exhaust device 501 enables the cooling and dilution of a relatively high rate of exhaust gases released into the atmosphere, because there are two separate gas flows released out of the main chamber.

Figure 9 illustrates an exhaust device 601 accord ing to a sixth embodiment of the invention. The description of exhaust device 1 given above with reference to figure 8 can be transposed to exhaust device 601 of figure 9, which is similar thereto, with the noticeable exception of the hereafter stated difference(s). An element of exhaust device 601 that has a structure or function similar or corresponding to that of an element of exhaust device 501 is given the same reference numeral plus 100.

One can thus define exhaust device 601 , gas inlet 602, a first and a second gas outlets 603 and 603B, a main chamber 604, a first and a second upstream wall 612 and 612B, a first and a second downstream wall 61 3 and 61 3 B and a fi rst and a second intermediate cha mber 61 5 and 615B.

Exhaust device 601 mainly differs from exhaust device 501 , because exhaust device 601 also comprises a first and a second baffle 616 and 616B, which have similar structure and function as the baffle 16 of exhaust device 1 .

Besides, exhaust device 601 differs from exhaust device 501 , because exhaust device 601 further comprises two vortex generators 617 and 6 1 7 B . T h e two vo rte x g e n e ra to rs 6 1 7 a n d 617B are arranged symmetrically relative to the main chamber 604 and respectively on each downstream wall 613 and 613B.

Th u s , the vortex gene rators 61 7 a nd 617B help maintain turbulent the gas flows released out of gas outlets 603 and 603B. The vortex generators would promote turbulence and mixing of the exhaust gases with ambient air. Such vortex generators are preferably located at a certain distance from the gas outlet where the flow of gas along the downstream walls 613, 613B would, even without such vortex generators, tend to become turbulent rather than flowing smoothly along the wall.

Figure 10 illustrates an exhaust device 701 according to a seventh embodiment of the invention. The description of exhaust device 301 g iven above with refe rence to fig u re 6 ca n be transposed to exhaust device 701 of figure 10, which is similar thereto, with the noticeable exception of the hereafter stated difference(s). An element of exhaust device 701 that has a structure or function similar or corresponding to that of an element of exhaust device 301 is given the same reference numeral plus 400.

One can thus define exhaust device 701 , gas inlet 702, gas outlet 703, a trailing edge 703.2, a main chamber 704, an upstream wall 712 and a downstream wall 713.

Exhaust device 701 mainly differs from exhaust device 301 , because the outer surface of the downstream wall 713 comprises a concave portion 713.1 and a convex portion 713.2. In other words, the outer surface of downstream wall 71 3 i s not total ly convex. Only the intermediate portion formed by convex portion 71 3.2 is convex.

The concave portion 71 3.1 is located farther away from the gas outlet 703 than the convex portion 71 3.2 along the direction of the flow of exhaust gases. The convex portion 713.2 is located , along the downstream wall 713 and away from the gas outlet 703, preferably along at least 20 times the width H703 of gas outlet 703, width H703 representing the smallest dimension among the main dimensions generally defining the outlet perimeter of gas outlet 703.

Alike the other embodi ments of the invention, exhaust device 701 enables the cooling and dilution of exhaust gases released into the atmosphere out of gas outlet 703..

Figures 1 1 , 12 and 1 3 illustrate an exhaust device 801 according t o an eighth embodiment of the invention. The description of exhaust device 501 g iven above with reference to figure 8 ca n be tra nsposed to exhaust device 801 of figures 1 1 , 12 and 1 3, which is similar thereto, with the noticeable exception of the hereafter stated difference(s). An e le me nt of exhaust device 801 that has a structure or function similar or corresponding to that of an element of exhaust device 501 is given the same reference numeral plus 300.

One can thus define exhaust device 801 , gas inlet 802, a first and a second gas outlets 803 and 803B, a main chamber 804, a first and a second upstream wall 812 and 812B, a first and a second downstream wall 81 3 and 813B and a first and a second intermediate chamber 815 and 81 5B, baffles 816 and 816B.

As i l lustrated at figures 1 1 and 13, the exhaust device 801 mainly differs from exhaust device 501 , because the main chamber 804 and the pipe section 805 are both cylindrical with a circular basis and coaxial. Thus, exhaust device 801 is relatively compact and easy to manufacture. Furthermore, the main chamber 804 and the pipe section 805 have the same circular, cylindrical shape, so that the transition between main chamber 804 and pipe section 805 does not generate too much pressure drop.

Besides, as illustrated at figure 12, exhaust device 801 further comprises two symmetrical flow deflectors 818 and 818B. Each flow deflector 818 or 818B is located at the upstream end of a respective inner wall 814 or 814B thus forming an intermediate chamber 815 or 815B. Each flow deflector 81 8 or 81 8B has a cylindrical shape and extends along the longitudinal direction of the respective gas outlet 803 or 803B, hence along most of the length of gas outlet 803.

Thus, flow deflectors 818 and 818B limit the turbulences in the exhaust gases flowing from main chamber 804 into intermediate chamber 815 or 815B, thus increasing the air suction efficiency of exhaust device 801. Furthermore, flow deflectors 818 and 818B stiffen the structure of exhaust device 801.

Figures 14 and 15 illustrate an exhaust device 901 according to a ninth embodiment of the invention. The description of exhaust device 201 given above with reference to figure 5 can be transposed to exhaust device 901 of figures 14 and 15, which is similar thereto, with the noticeable exception of the hereafter stated difference(s). An element of exhaust device 901 that has a structure or function similar or corresponding to that of an element of exhaust device 201 is given the same reference numeral plus 700.

One can thus define exhaust device 901 , a gas inlet 902, a gas outlet 903, a trailing edge 903.2, a main chamber 904 and pipe section 905, an upstream wall 912, a downstream wall 91 3, an inner wall 914 and an intermediate chamber 915.

On figures 14, 1 5 and 16, the pathlines in full lines represent relatively hot gases, i.e. gases entering the exhaust device 901 , whereas the pathlines in dotted lines represent relatively cool gases, i.e. gases released out of exhaust device 901 . Upstream air flow is not represented by pathlines at figures 14 and 15.

Exhaust device 901 differs from exhaust device 201 , because gas outlet 903 extends in a direction X which is perpendicular to axis Y parallel to which extends the main chamber 904. In other words, the inlet gas flow direction F902 is substantially parallel to the outlet gas flow direction F903. Consequently, pipe section 905 has a different shape.

Such an exhaust device can generate a relatively low pressure drop. Besides, such a construction provides more compacity . Figures 17 and 18 illustrate an exhaust device 1 101 according to an tenth embodiment of the invention. The description of exhaust device 601 given above with reference to figure 9 can be transposed to exhaust device 1 101 of figures 17 and 18, which is similar thereto, with the noticeable exception of the hereafter stated difference(s). An element of exhaust device 1 101 that has a structure or function similar or corresponding to that of an element of exhaust device 601 is g iven the same reference numeral plus 500.

One can thus define exhaust device 1 101 , a gas inlet 1 102, two gas outlets 1 103 and 1 103B, a main chamber 1 104 and pipe section 1 105, two upstream walls 1 1 12 and 1 1 12B, two downstream walls 1 1 13 and 1 1 13B, and two baffles 1 1 16 and 1 1 16B.

Exhaust device 1 101 differs from exhaust device 601 , because each downstream wall 1 1 13 or 1 1 13B has a generally plane outer surface. Such a plane outer surface forms, with the exhaust direction D1 103, an angle A1 103 of about 25° as measured in plane XVIII. Plane XVIII is perpendicular both to gas outlet 1 103 and to the plane outer surface.

The exhaust direction D1 103 corresponds to an average direction along which the flow F1 103 of exhaust gases is released from gas outlet 1 103. Angle A1 103 can range from 1 ° to 35°, so as to entrain an appropriate rate of air flow F1 102.

An angle similar to angle A1 103 can be measured for gas outlet

1 103B.

The plane outer surface is preferably preceded by another portion which is effectively tangent to the flow of exhaust gases at the gas outlet 1 103, and these two portions are connected either smoothly or by a sudden angulations or by a series of successive angulations.

Alternatively, the plane portion of the downstream wall 1 1 13 might extend directly from the gas outlet 3. As in exhaust device 601 , the distance between the downstream wall 1 1 13 and a plane tangent P1 1 13 at the gas outlet 1 103 generally increases with the distance to the gas outlet 1 103, if it then admitted that the plane P1 1 13 is the plane tangent to the flow direction F3 at the gas outlet 3.

As in exhaust device 601 , the downstream wall 1 1 13 is arranged with respect to the gas outlet 1 103 so that the exhaust gases flow out of the gas outlet 1 1 03 substantially along the exhaust direction D1 1 03 d iverging from the downstream wall 1 1 1 3, but, further away, the exhaust gases tend to follow the downstream surface due to a Coanda effect.

Figures 19 and 20 illustrate a vehicle 100 having an internal combustion engine 121 and an exhaust system 122. The exhaust system 122 can comprise a Diesel particulate filter 123 and a terminal exhaust pipe 124 located at the downstream end of exhaust system 1 22. The vehicle 1 00 further comprises an exhaust device 101 according to the invention.

The exhaust device 101 comprises a gas outlet 103 and a main chamber 104. The exhaust device 101 further comprises:

a release opening 1 1 8 located at one end of the main chamber 104; the release opening 1 18 is connected to the exhaust pipe 124;

a shutter 1 19 which is arranged to be mobile between: an open position (fig.18) , in which the exhaust gases flow th roug h the release open i ng 1 18 towards exhaust pipe 124 (see arrow F124),

and a closed position (fig.17), in which the exhaust gases are prevented from flowing through the release opening 1 18, such that the exhaust gases flow through the gas outlet 103 (see arrow F103).

Thus, the flowpath extending between gas inlet 102 and release opening 1 1 8 can generate less pressure drop than the flowpath extending between gas inlet 102 and gas outlet 103.

I n service, when the vehicle is not at standstill, e.g. when an industrial vehicle is in a haulage phase, the shutter 1 19 can be set open to decrease pressure drop within the exhaust system 1 22. When the vehicle is at standstill to operate a regeneration process of the Diesel pa rticulate filter 123 and/or of a not shown selective catalytic red uction com po nent, shutter 1 1 9 is closed to ensure cooling and dilution of exhaust gases released out of the exhaust system 122.

The shutter can be controlled depending on the temperature of the exhaust gases F102 entering the gas inlet 102.

Figures 21 and 22 illustrate an alternative, flow sensitive shutter 21 9 which can be mounted in lieu of controlled shutter 1 19. Flow sensitive shutter 219 moves in dependence to the gas flow rate passing through the exhaust system 122. Thus, flow sensitive shutter 219 can move continuously between different, adjacent positions.

A further embodiment of an exhaust device may have two main chambers, each chamber being for example similar to the one described in relation to Figure 5. The two main chambers are arranged in a mirror configuration so that their respective gas outlets, upstream wall and downstream wall are facing each other. With such a configuration, the entire volume comprised between the respective main chambers forms a flow path in which air can be entrained from both.

Of course, the invention is not restricted to the embodiments described above by way of non-limiting examples, but on the contrary it encompasses all embodiments thereof.

Claims

1. An exhaust device (1 ; 101 ; 201 ; 301 ; 401 ; 501 ; 601 ; 701 ; 801 ; 901 ; 1001 ; 1 101 ), for a vehicle (100) of the type having an internal combustion engine (121 ) and an exhaust system (122), the exhaust device (1 ; 101 ; 201 ; 301 ; 401 ; 501 ; 601 ; 701 ; 801 ; 901 ; 1001 ; 1 101 ) comprising at least:

a gas outlet (3 ; 103 ; 203 ; 303 ; 403 ; 503 ; 603 ; 703 ; 803 ; 903 ; 1 103) suitable for releasing exhaust gases into the atmosphere, the gas outlet being substantially shaped as a slot;

a downstream wall (13 ; 213 ; 313 ; 413 ; 513 ; 613 ; 713 ; 813 ; 913 ; 1013 ; 1 1 13) extending downstream of the gas outlet and along most or all of the length (L3) of said gas outlet (3 ; 103 ; 203 ; 303 ; 403 ; 503 ; 603 ; 703 ; 803 ; 903 ; 1 103), the downstream wall having an outer surface (13.4) arranged to be in contact with the exhaust gases flowing out of the gas outlet;

wherein the gas outlet and the downstream wall are arranged respectively so that the exhaust gases flow out of the gas outlet (3 ; 103 ; 203 ; 303 ; 403 ; 503 ; 603 ; 703 ; 803 ; 903 ; 1 103) substantially tangentially to the downstream wall (13 ; 213 ; 313 ; 413 ; 513 ; 613 ; 713 ; 813 ; 913 ; 1013 ; 1 113);

and wherein the distance between the downstream wall (13 ; 1 1 13) and a plane tangent (P13 ; P1 1 13) to the downstream wall (13 ; 1 1 13) at the gas outlet (3 ; 1 103) generally increases with the distance from the gas outlet (3 ; 1 103).

2. An exhaust device (1 ; 1 01 ; 201 ; 301 ; 401 ; 501 ; 601 ; 701 ; 801 ; 901 ) according to claim 1 , wherein the downstream wall has a generally convex outer surface.

3. An exhaust device (1 ; 701 ) according to claim 2, wherein at least an intermediate portion (713.2) of the outer surface of the downstream wall (13 ; 713) is convex, the intermediate portion (713.2) extending, along the downstream wall (13 ; 713) and away from the gas outlet (3 ; 703), along a distance which is preferably at least 10 times, preferably at least 20 times, and most preferably at least 30 times the smallest dimension (H3 ; H703) among the main dimensions generally defining the gas outlet (3; 703).

4. An exhaust device according to claim 3, wherein the whole outer surface of the downstream wall (13 ; 213 ; 313 ; 413 ; 513 ; 613 ; 813 ; 913) is convex.

5. An exhaust device (701) according to any one of claims 1 to 3, wherein the outer surface of the downstream wall (713) comprises at least a plane portion or a concave portion (713.1).

6. An exhaust device (1101) according to any preceding claim, wherein the downstream wall (1113) has a generally plane outer surface.

7. An exhaust device according to claim 6, wherein said plane outer surface and the plane tangent (P13 ; P1113) to the downstream wall (12 ; 1112) at the gas outlet (1103) form an angle (A1103) ranging from 1° to 35° in a plane (XVIII) perpendicular to the gas outlet (1103) and to the plane outer surface.

8. An exhaust device according to any preceding claim, wherein the gas outlet (3 ; 203 ; 303 ; 403 ; 503 ; 603 ; 703 ; 803 ; 903 ; 1103) is elongated along a straight line.

9. An exhaust device according to any preceding claim, wherein the exhaust device comprises a main chamber (4 ; 104 ; 204 ; 304 ; 404 ; 504 ; 604 ; 704 ; 804 ; 904 ; 1104) delimited by peripheral walls, wherein the gas outlet (3 ; 203 ; 303 ; 403 ; 503 ; 603 ; 703 ; 803 ; 903 ; 1103) is arranged in said peripheral walls and wherein said downstream wall (13 ; 213 ; 313 ; 413 ; 513 ; 613 ; 713 ; 813 ; 913 ; 1013 ; 1113) is a peripheral wall of the chamber.

10. An exhaust device according to claim 9, wherein said peripheral walls of the main chamber (4 ; 104 ; 204 ; 304 , 404 ; 504 ; 604 ; 704 ; 804 ; 904 ; 1104) comprise an upstream wall (12 ; 212 ; 312 ; 412 ; 512 ; 612 ; 712 ; 812 ; 912 ; 1112) extending upstream of the gas outlet and along most or all of the length (L3) of said gas outlet (3 ; 103 ; 203 ; 303 ; 403 ; 503 ; 603 ; 703 ; 803 ; 903 ; 1103), the upstream wall having an inner surface (12.4) arranged to be in contact with the exhaust gases flowing towards the gas outlet.

11. An exhaust device according to claim 10, wherein, along the gas outlet, the upstream wall (12 ; 212 ; 312 ; 412 ; 512 ; 612 ; 712 ; 812 ; 912 ; 1112) is arranged so as be substantially parallel to the plane (P13 ; P1113) tangent to the downstream wall (13 ; 1113) at the gas outlet (3 ; 1103).

12. An exhaust device according to claim 11, wherein the upstream wall (12 ; 212 ; 312 ; 412 ; 512 ; 612 ; 712 ; 812 ; 912 ; 1112) is offset from said plane (P13 ; P1113) tangent to the downstream wall (12 ; 1112), according to a direction perpendicular to said plane (P13 ; P1113).

13. An exhaust device according to any one of claims 10 to 13, further comprising an inner wall (14 ; 214 ; 414 ; 514 ; 614 ; 814 ; 914) extending inside said main chamber (4 ; 104 ; 204 ; 304 ; 404 ; 504 ; 604 ; 704 ; 804 ; 904) and upstream of the gas outlet (3 ; 203 ; 403 ; 503 ; 603 ; 803 ; 903) and opposite a downstream portion of the upstream wall (12 ; 212 ;

412 ; 512 ; 612 ; 812 ; 912) so as to define at least one intermediate chamber (15 ; 215 ; 415 ; 515 ; 615 ; 815 ; 915) which is arranged to guide the flow of exhaust gases substantially tangentially to the downstream wall (13 ; 213 ;

413 ; 513 ; 613 ; 813 ; 913).

14. An exhaust device according to claim 13, wherein a length of the intermediate chamber (15 ; 215 ; 415 ; 515 ; 615 ; 815 ; 915), considered along the upstream wall (12 ; 212 ; 412 ; 512 ; 612 ; 812 ; 912), is at least 10 times, preferably at least 20 times and most preferably at least 30 times the smallest dimension (H3) among the main dimensions generally defining the gas outlet.

15. An exhaust device according to any one of claims 13 or 14, wherein the intermediate chamber (15 ; 215 ; 415 ; 515 ; 615 ; 815 ; 915) defines a convergent flow path for the exhaust gases.

16. An exhaust device according to any one of claims 13 to 15, wherein the downstream wall (13 ; 213 ; 413 ; 513 ; 613 ; 813 ; 913) prolongs the inner wall (14 ; 214 ; 414 ; 514 ; 614 ; 814 ; 914).

17. An exhaust device (801) according to any one of claims 13 to 16, further comprising a flow deflector (818, 818B) partially or totally cylindrical, the flow deflector (818, 818B) being located at the upstream end of the inner wall (14 ; 214 ; 414 ; 514 ; 614 ; 814 ; 914), the flow deflector (818, 818B) extending along most or all of the length of the gas outlet (803).

18. An exhaust device (1 ; 401 ; 601 ; 801) according to any one of claims 10 to 17, further comprising at least one solid baffle located away from the main chamber and arranged at a substantially constant distance from the upstream wall (12 ; 412 ; 612 ; 812) and from the downstream wall (13 ; 413 ; 613 ; 813).

19. An exhaust device (1001) according to any preceding claim, wherein the downstream wall (1013) comprises at least two separate wings (1013.5, 1013.6, 1013.7, 1013.8).

20. An exhaust device (1001) according to claim 19, wherein each wing (1013.5) is mobile relative to another wing (1013.6, 1013.7, 1013.8).

21. An exhaust device (101) according to any preceding claim, further comprising at least: a release opening (118) located at one end of the main chamber (204);

a shutter (119 ; 219) arranged to be mobile between an open position, in which the exhaust gases (F102) flow through the release opening (118), and a closed position, in which the exhaust gases (F102) are prevented from flowing through the release opening (118), such that the exhaust gases (F102) flow through the gas outlet (103).

22. An exhaust device according to claim 21, wherein the shutter (119 ; 219) is controlled depending on the temperature of the exhaust gases (F102) entering the gas inlet (102) and/or depending on the vehicle speed.

23. An exhaust device according to any preceding claim , wherein the gas outlet (3 ; 203 ; 303 ; 403 ; 503 ; 603 ; 703 ; 803 ; 903) is the sole outlet (4 ; 204 ; 304 ; 404 ; 504 ; 604 ; 704 ; 804 ; 904).

24. An exhaust device (501 ; 601 ; 801) according to any preceding claim, comprising at least two gas outlets (503, 503B ; 603, 603B ; 803, 803B) arranged so that the exhaust gases flow out of each gas outlet (503, 503B ; 603, 603B ; 803, 803B) in a direction substantially tangential to a respective downstream wall (513 ; 613 ; 813).

25. An exhaust device (501 ; 601 ; 801) according to claim 24, comprising two gas outlets arranged so that the exhaust gases flow out of each gas outlet (503, 503B ; 603, 603B ; 803, 803B) in two directions which are substantially convergent.

26. A vehicle (100) having an internal combustion engine (121) and an exhaust system (122), in particular of the type comprising a Diesel particulate filter (123) and/or a selective catalytic reduction component, the vehicle (100) being characterized in that it further comprises at least one exhaust device (1 ; 101 ; 201 ; 301 ; 401 ; 501 ; 601 ; 701 ; 801 ; 901 ; 1001) according to any preceding claim.