EP3575567B1

EP3575567B1 - Exhaust diffuser for an after treatment system of an internal combustion engine and after treatment system comprising said diffuser

Info

Publication number: EP3575567B1
Application number: EP19186385.1A
Authority: EP
Inventors: Christian Krug; Antonio Benetti
Original assignee: Iveco SpA
Current assignee: Iveco SpA
Priority date: 2016-09-15
Filing date: 2017-09-15
Publication date: 2021-06-30
Anticipated expiration: 2037-09-15
Also published as: ES2747552T3; EP3296534A1; IT201600093139A1; ES2887282T3; EP3296534B1; EP3575567A1

Description

FIELD OF THE INVENTION

The present invention relates to the field of tail pipes of after treatment systems in particular comprising diffusers in order to lower the exhaust gas temperature.

STATE OF THE ART KNOWN

The use of the gas diffusers as last component or tail pipe of the After Treatment Systems (ATS) of internal combustion engines is known. Examples of such devices are disclosed in US2008110164 .
The purpose of such devices is to lower the temperature of exhaust gas and mixing it with fresh air before being released into the environment.
Some layout of vehicles do not allow the installation of devices as the one shown in US2008110164 .
Therefore, it may happen that the space available is particularly compact. With "compact" it is meant that the sizes of the ATS are similar to each other, that is within a ratio between 1 and 4, in absolute value. This implies that the installation of the device shown in US2008110164 is difficult or impossible when the space dedicated to the ATS is particularly compact.
Other known devices are shown in documents US2010269493 A1 or US2007163247 A1 . In particular, US2010269493 A1 discloses the features of the preamble of claim 1.

SUMMARY OF THE INVENTION

The purpose of the present invention is to indicate a diffuser particularly suitable in those cases where the available space for ATS installation is limited and requires a compact ATS, in which a canning, housing the overall ATS, has a ratio, in absolute value, between two sizes within 1 and 4.
Such aims are solved by a diffuser according to the appended set of claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will become fully clear from the following detailed description, given by way of a mere exemplifying and non-limiting example, to be read with reference to the attached drawing figures, wherein:

Figure 1 shows a low perspective view of an embodiment of a gas diffuser, that is not part of the present invention but it is useful to its understanding;
Figure 2 shows an up perspective view of the same diffuser of Figure 1;
Figure 3 shows a low perspective view of a compact After treatment system (ATS) comprising the diffuser of the figures 1 and 2;
Figure 4 shows a lateral perspective view of the ATS of figure 3;
Figure 5 shows an up perspective view of an embodiment of a gas diffuser according to the present invention;
Figure 6 shows a low perspective view of the same diffuser of Figure 5;
Figure 7 shows a low perspective view of the ATS of figure 3 where the diffuser of figures 5 and 6 is implemented;
Figure 8 shows a scheme of the ATS of figure 3, 4 and 7 according to a longitudinal development of the ATS.

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to an exhaust diffuser D, D' for an After Treatment System (ATS) of an internal combustion engine.
The diffuser comprises a first portion FP having a tubular frusto-pyramidal shape developing according to a first axis Y and has an inlet IN, IN', for receiving exhaust gas from said ATS, proximal to a minor basis MNB of the truncated pyramid and a second portion SP, contiguous with and subsequent to said first one, according to an exhaust gas circulation, wherein said second portion comprises two or more separate paths PTH communicating with the outside, arranged side-by-side between each other according to said developing axis Y.
Each path includes at least one ejector EJ arranged in such a way to suck fresh air from the outside of the diffuser.
In particular, a vane is cut by the casing itself of the second portion of the diffuser and is bent towards the inside of the second part so as it is superimposed to a corresponding hollow. Each vane lefts open its hollow and defines a sort of ramp for the circulating gas. Therefore, the gas meets the ramp, and thus a local section reduction, thus, for the Venturi's effect, accelerates. A low pressure is defined just after the ramp sucking fresh air from the outside of the device that is mixed with the exhaust gas in order to refresh the latter.
At least the first portion FP has a frusto-pydamidal shape with rectangular bases.
According to the embodiment defining the invention, i.e. relating on figures 5 to 7, a first FP and a second portion SP in one piece defining as a whole a frusto-pyramid are present. Thus, said second portion is defined inside the truncated-pyramid casing defining the diffuser.
In particular such frusto-pyramid is squeezed according to a second axis Z, perpendicular to said first axis Y, so as any cross-section perpendicular to said development axis is rectangular having two major and two minor segments corresponding to the two major UW, LW and the two minor MW walls of the frusto-pyramidal shape, wherein the minor segments have almost constant size along said development.
The second portion SP preferably comprises septum(s) SPT perpendicular to said major walls UW, LW of the frusto-pyramid, arranged in order to define said two or more separated paths PTH.
According to an embodiment according to the figures 1 to 4, not making part of the present invention but useful for its understanding, the first portion is (also) squeezed according to the second axis Z, perpendicular to said first axis and the second portion SP comprises two or more separate tubular pipes TM, each defining a path PTH, arranged substantially parallel between each other and pneumatically connected to a major basis MJB of the frusto-pyramid, opposite to the minor one MNB.
Preferably, any cross-section perpendicular to said development axis Y of said first portion FP is rectangular having major and minor segments corresponding to the two major UW, LW and the two minor MW walls of the frusto-pyramidal shape and wherein said two major walls diverge reciprocally and said two minor walls diverge reciprocally toward said major basis MJB.
For both the above described embodiments the inlet IN, IN' is arranged on one UW of said major walls close to said minor basis MNB and the minor basis is rounded and smoothly joined with the other wall LW of said two major walls in order to reduce turbulence.
Both the diffusers of the above described embodiments are provided with collars for a simple mounting on the outlet of the ATS disclosed according to the figures 3, 4 and 7.
In order to assure that the diffuser is fixedly connected to the ATS a V shaped flange FL has the opposite ends affixed to the ATS and the vertex affixed to the second portion of the diffuser.
The ATS has substantially a parallelepiped shape having a predominant development, parallel, within +/- 30°, with said first axis Y. The parallelepiped shape can be rectangular.
In operation, the diffuser is arranged under the ATS, according to a vertical direction parallel to said second axis Z.
According to both the above described embodiments of diffusers, the end CT of said second portion SP, corresponding to the outlet OUT of the diffuser D, D' is slightly bent downwardly in order to direct exhaust gas towards the ground.
Figure 8 discloses a compact ATS. The ATS is defined "compact" because its sizes along the coordinate axes Z, Y, X are substantially comparable to each other, being in the mutual ratio of no more than 4.
Also the ATS is provided with flanges FL' to affix the ATS to the vehicle chassis. They are preferably parallel to the development axis Y of the ATS.
Said ATS schematizes the ones of the figures 3,4 and 7 sectioned according to the plane X-Z.
An inlet opening INL, preferably oriented along the Y axis, receives the combustion engine exhaust gas, represented by arrows FLW, which enters into a first chamber CH1, operatively communicating with a second chamber CH2 in which is housed the catalytic material on a carrier structure, which communicates with a third chamber CH3 turning the gas flow and orientating the flow lines for an accurate Lambda measurement, which communicates with a fourth CH4 chamber, made in a low part of the ATS, so as to be connected and communicating with the diffuser D, D' via the duct, schematized with the collar CL. An ejector permits a flow of fresh air FAI to inter in the diffuser to lower the exhaust gas.
From the scheme, it is clear that the upper wall UW of the two major walls of the frusto-pyramid coincides with a lower wall of the canning itself of the ATS.

Claims

Exhaust diffuser (D, D') for an After Treatment System (ATS) of an internal combustion engine comprising a first portion (FP) having a tubular frusto-pyramidal shape developing according to a first axis (Y), having an inlet (IN, IN'), for receiving exhaust gas from said ATS, proximal to a minor basis (MNB) of the truncated pyramid, and a second portion (SP), contiguous with and subsequent to said first one, according to an exhaust gas circulation, wherein said second portion comprises two or more separate paths (PTH) communicating with the outside, arranged side-by-side between each other according to said developing axis (Y), and wherein each path includes at least one ejector (EJ) arranged in such a way to suck fresh air from the outside of the diffuser
wherein said first portion (FP) is squeezed according to a second axis (Z), perpendicular to said first axis, so as any cross-section perpendicular to said development axis is rectangular having two major and two minor segments corresponding to the two major (UW, LW) and the two minor (MW) walls of the frusto-pyramidal shape, wherein the minor segments have almost constant size along said development,
wherein said second portion is defined inside said truncated-pyramid shape so as the overall shape of the diffuser is frusto-pyramidal, and wherein said second portion comprises septum(s) (SPT) perpendicular to said major walls (UW, LW) arranged in order to define said two or more separated paths (PTH).
Diffuser according to claim 1, wherein said ejector comprises a hollow and a vane folded inside its respective path, defining a ramp superimposed to said hollow.
Diffuser according to any of the preceeding claims, wherein said inlet (IN, IN') is arranged on one (UW) of said major walls close to said minor basis (MNB) and wherein said minor basis is rounded and smoothly joined with the other wall (LW) of said two major walls.
After treatment system (ATS) having a diffuser according to any of the preceding claims.