U.S. patent application number 12/874623 was filed with the patent office on 2011-05-05 for assembly for cooling an exhaust gas stream.
Invention is credited to Romain Brunet, Mattias Lang.
Application Number | 20110099990 12/874623 |
Document ID | / |
Family ID | 43530125 |
Filed Date | 2011-05-05 |
United States Patent
Application |
20110099990 |
Kind Code |
A1 |
Lang; Mattias ; et
al. |
May 5, 2011 |
ASSEMBLY FOR COOLING AN EXHAUST GAS STREAM
Abstract
An assembly for cooling an exhaust gas stream includes an outlet
nozzle exposed to the exhaust gas stream. The outlet nozzle
projects into an open end of an adjacent exhaust gas pipe so that a
reduced pressure relative to the surrounding environment is
produced in a suction region between the outlet nozzle and the
exhaust gas pipe by flow of exhaust gas. Adjusting members vary the
flow cross section of the outlet nozzle.
Inventors: |
Lang; Mattias;
(Ubstadt-Weiher, DE) ; Brunet; Romain; (Mannheim,
DE) |
Family ID: |
43530125 |
Appl. No.: |
12/874623 |
Filed: |
September 2, 2010 |
Current U.S.
Class: |
60/320 |
Current CPC
Class: |
F01N 13/082 20130101;
F01N 2590/08 20130101; F01N 2270/02 20130101 |
Class at
Publication: |
60/320 |
International
Class: |
F01N 5/02 20060101
F01N005/02 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 30, 2009 |
DE |
102009046253.8 |
Claims
1. A assembly for cooling an exhaust gas stream, having an outlet
nozzle exposed to the exhaust gas stream, the outlet nozzle
projecting into an open end of an adjacent exhaust gas pipe so that
a reduced pressure relative to the surrounding environment is
produced in a suction region between the outlet nozzle and the
exhaust gas pipe as a result of exhaust gas flow, characterized by:
the outlet nozzle comprises adjusting members for varying a flow
cross section of the outlet nozzle.
2. The assembly according of claim 1, wherein: the adjusting
members vary the flow cross section as a function of an exhaust gas
temperature.
3. The assembly of claim 1, wherein: the outlet nozzle comprises a
plurality of flexible fins for varying the flow cross section.
4. The assembly of claim 3, wherein: the fins comprise bimetallic
elements, which assume a curvature which reduces the flow cross
section of the outlet nozzle as the exhaust gas temperature
increases.
5. The assembly of claim 3, wherein: the fins rest against an open
end of the exhaust gas pipe when the exhaust gas stream temperature
is below a predetermined threshold value.
6. The assembly of claim 3, wherein: the open end of the exhaust
gas pipe includes a limiting member; and the fins rest on the
limiting member.
7. The assembly of claim 1, wherein: a portion of the exhaust gas
pipe is surrounded by a touch guard.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to an assembly for cooling an
exhaust gas stream.
BACKGROUND OF THE INVENTION
[0002] The exhaust gas standards enacted by the European Union
provide for a gradual reduction in the soot particles produced by
diesel engines and discharged into the environment with the engine
exhaust gas. Soot particle discharge is restricted by using soot
particle filters, as a rule with "wall-flow filters", in which the
engine exhaust gas passes through a porous filter wall of a ceramic
or metallic material. In so doing, the soot particles contained in
the engine exhaust gas become deposited both on the surface of and
also inside the filter wall, such that the exhaust gas
back-pressure increases as the degree of clogging of the filter
wall increases. To regenerate the soot particle filter, the
deposited soot particles are therefore burned off at regular
intervals, for which purpose the temperature of the engine exhaust
gas is increased from time to time to temperatures of over
600.degree. C., for example using an oxidation catalytic converter
connected upstream of the soot particle filter. During the
regeneration phases of the soot particle filter correspondingly
high exhaust gas temperatures may occur at the exhaust tail pipe of
the exhaust gas system, which may possibly constitute a hazard for
nearby vehicle components, objects or people.
[0003] Against this background, WO 2008/060559 A2 discloses a
device for reducing the exhaust gas temperature at an exhaust tail
pipe. The device, which may be fitted to the exhaust tail pipe by
means of a clip or clamp, comprises a nozzle, which is fitted by
means of a plurality of radially arranged holding struts in such a
way on an adjoining diverter housing that, on passage of the
exhaust gas stream, a partial vacuum for drawing in cooler ambient
air may be produced in an inlet formed between the nozzle and the
diverter housing. However, the shape of the nozzle or of the
diverter housing, which shape tapers in the passage direction of
the exhaust gas stream, leads to an undesired increase in the
exhaust gas back-pressure in the exhaust gas system.
SUMMARY
[0004] Accordingly, an object of this invention is to provide an
exhaust gas cooling assembly which prevents an undesired increase
in the exhaust gas back-pressure during regeneration phases of the
soot particle filter.
[0005] This and other objects are achieved by the present
invention, wherein an assembly for cooling an exhaust gas stream
includes an outlet nozzle exposed to the exhaust gas stream. The
outlet nozzle projects into an open end of an adjacent exhaust gas
pipe so that a reduced pressure relative to the surrounding
environment is produced in a suction region between the outlet
nozzle and the exhaust gas pipe due to the flow of the exhaust gas
stream. Furthermore, an adjusting device is provided for varying
the flow cross section of the outlet nozzle.
[0006] More precisely, the reduced pressure is produced by the
Venturi principle, the outlet nozzle extending into the open end of
the exhaust gas pipe and producing a reduced pressure in the
suction region as a function of the flow cross section. The ambient
air drawn into the exhaust gas pipe due to the reduced pressure
leads in the process, depending on the temperature thereof, to
corresponding cooling of the exhaust gas stream.
[0007] Since the addition of cooler ambient air is needed only
during the regeneration phases of the soot particle filter, during
the other operating phases of the soot particle filter the flow
cross section of the outlet nozzle may be enlarged by the adjusting
device such that the exhaust gas stream can pass through
unhindered. In this way, an undesired increase in the exhaust gas
back-pressure may be restricted to the regeneration phases of the
soot particle filter.
[0008] The assembly has a particularly simple structure which fits
compactly in the region of the soot particle filter inside an
engine compartment of a diesel-engine powered motor vehicle, such
as an agricultural utility vehicle. Cooling of the diesel engine is
conventionally achieved by a high temperature heat exchanger
arranged in the engine compartment of the motor vehicle, which heat
exchanger is a component of a liquid cooling circuit connected with
the diesel engine. The high temperature heat exchanger is exposed
to cooling air by a fan unit. Cooling air is drawn from the
surrounding environment by way of a radiator grille and downstream
filter inserts. Since the air conveyed in this way into the engine
compartment is largely free of contaminants, undesired clogging of
the suction region formed between the outlet nozzle and the exhaust
gas pipe is reliably avoided. In addition, the compression of the
air located in the engine compartment by the fan unit, leads to an
increased volumetric flow rate in the suction region and thus to
more efficient cooling of the exhaust gas stream.
[0009] The flow cross section of the outlet nozzle is preferably
varied as a function of the exhaust gas temperature. In particular,
provision may be made for the flow cross section to be enlarged by
the adjusting device in the case of exhaust gas temperatures
typically arising during a regeneration phase of the soot particle
filter.
[0010] The outlet nozzle may comprise a plurality of flexible fins
for varying the flow cross section. The fins take the form for
example of finger-shaped baffle plates, which are one-piece
components of a fastening strip mountable on an outlet connector of
the soot particle filter, the baffle plates projecting towards the
exhaust gas stream when fitted. The outlet connector is in
particular a fixed component of a filter housing surrounded by the
soot particle filter and is welded or otherwise firmly connected
thereto.
[0011] The fins are preferably bimetallic elements, which assume a
curvature which reduces the flow cross section of the outlet nozzle
as the exhaust gas temperature increases. In other words, the
bimetallic elements constitute an adjusting device for
temperature-dependent variation of the flow cross section of the
outlet nozzle. The structure of such bimetallic elements is known
in principle. Accordingly, they consist of a metal strip, which
comprises two joined-together metal layers with different
coefficients of longitudinal expansion.
[0012] The fins are preferably configured so that they rest against
the open end of the exhaust gas pipe when the exhaust gas
temperature is below a predetermined threshold value. In this case
the fins adopt a fully open position. The threshold value is preset
such that it is below the exhaust gas temperatures in the range of
from 400 to 600.degree. C. typically occurring during the
regeneration phase of the soot particle filter.
[0013] A limiting member is provided at the open end of the exhaust
gas pipe for the fins to rest on. The limiting members form of a
stop lip extending around the inside of the open end of the exhaust
gas pipe. The stop lip forms a flange at the open end of the
exhaust gas pipe. A heat-resistant seal in the form of a braided
glass or ceramic fibre cord may additionally be introduced into the
flange.
[0014] Moreover, the fins may be arranged overlapping in the manner
of a diaphragm in the circumferential direction of the outlet
nozzle. The overlap reliably prevents an undesired release of
exhaust gases in the region of the outlet nozzle.
[0015] Preferably, the exhaust gas pipe is surrounded at least in
places by a touch guard. The touch guard takes the form in
particular of a tubular cover, which is fitted along the outside of
the exhaust gas pipe by means of a plurality of spacers. To prevent
overheating of the exhaust gas pipe, the tubular cover may include
a plurality of openings at least in the region of an exhaust tail
pipe, which allow circulation of the air present between the
exhaust gas pipe and the tubular cover.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] FIG. 1 is a perspective view of an exhaust gas cooling
assembly according to the invention, mounted on a vehicle;
[0017] FIG. 2 is a detailed view of the assembly of FIG. 1, during
a regeneration phase of the soot particle filter; and
[0018] FIG. 3 is a detailed view of the assembly of FIG. 1 outside
a regeneration phase of the soot particle filter.
DESCRIPTION OF THE PREFERRED EMBODIMENT
[0019] Referring to FIG. 1, an agricultural utility vehicle 10,
such as a tractor, includes a soot particle filter 14 accommodated
in an engine compartment 12. The soot particle filter is a
conventional wall-flow filter. The exhaust gas produced by a diesel
engine 16 of the vehicle 10 passes through a porous filter wall of
a ceramic or metallic material. In the process, the soot particles
contained in the engine exhaust gas become deposited both on the
surface of and also inside the filter wall of the soot particle
filter 14. Since the exhaust gas back-pressure increases as the
degree of clogging of the filter wall increases, the deposited soot
particles are burned at regular intervals to regenerate the soot
particle filter 14, for which purpose the temperature of the engine
exhaust gas is increased from time to time to temperatures of over
600.degree. C. using an oxidation catalytic converter connected
upstream of the soot particle filter 14.
[0020] To cool the exhaust gas stream 18 emerging from the soot
particle filter 14 and heated during the regeneration phase, the
assembly 20 includes an outlet connector 22 formed on the soot
particle filter 14 for conveying out the filtered exhaust gas
stream 18. An outlet nozzle 24 fitted on the outlet connector 22
and exposed to the exhaust gas stream 18 projects into an open end
26 of an adjacent exhaust gas pipe 28 so that a reduced pressure
relative to the surrounding environment 32 is produced in a suction
region 30 between the outlet nozzle 24 and the exhaust gas pipe 28
by the flow of the exhaust gas stream 18, as best seen in FIG.
2.
[0021] More precisely, the reduced pressure is produced by the
Venturi principle, the outlet nozzle 24 extending into the open end
26 of the exhaust gas pipe 28 and producing a reduced pressure in
the suction region 30 as a function of the respective flow cross
section. Ambient air 34 is drawn into the exhaust gas pipe 28 due
to the reduced pressure leads in the process, depending on the
temperature thereof, to cool the exhaust gas stream 18.
[0022] Furthermore, the outlet nozzle 24 includes a plurality of
flexible fins 36 for varying the flow cross section. The fins are
arranged overlapping in the manner of a diaphragm in the
circumferential direction of the outlet nozzle 24. The fins 36 take
the form of finger-shaped baffle plates, which are one-piece
components of a fastening strip 40 mounted on an outlet connector
22 by means of a clamping screw 38. The baffle plates project
towards the exhaust gas stream 18 when fitted. The outlet connector
22 is a fixed component of a filter housing 42 surrounded by the
soot particle filter 14 and is welded or otherwise firmly connected
thereto.
[0023] The fins 36 are bimetallic elements, which assume a
curvature which reduces the flow cross section of the outlet nozzle
24 as the exhaust gas temperature increases. In other words, the
bimetallic elements constitute an adjusting device 44 for varying
the flow cross section of the outlet nozzle 24 as a function of the
exhaust gas temperature.
[0024] Moreover, the fins 36 are configured so that they rest
against the open end 26 of the exhaust gas pipe 28 when the exhaust
gas temperature is below a predetermined threshold value. In this
case, the fins 36 adopt a completely open position, to allow the
exhaust gas stream 18 to pass through unhindered, as best seen in
FIG. 3. The threshold value is preset below the exhaust gas
temperatures in the range of from 400 to 600.degree. C. typically
occurring during the regeneration phase of the soot particle filter
14.
[0025] At the open end 26 of the exhaust gas pipe 28 a limiting
member 46 is provided for the fins 36 to rest on. The limiting
member 46 takes the form of a stop lip 50 extending around the
inside 48 of the open end 26 of the exhaust gas pipe 28. The stop
lip 50 comprises for example a flange formed at the open end 26 of
the exhaust gas pipe 28. A heat-resistant seal 52 in the form of a
braided glass or ceramic fibre cord may additionally be introduced
into the flange.
[0026] According to FIG. 1, the exhaust gas pipe 28 is surrounded
at least in places by a touch guard 54. The touch guard 54 is a
tubular cover 56, which is fitted along the outside of the exhaust
gas pipe 28 by means of a plurality of spacers (not shown). To
prevent overheating of the exhaust gas pipe 28, the tubular cover
56 comprises a plurality of openings 60 at least in the region of
an exhaust tail pipe 58, which allow circulation of the air present
between the exhaust gas pipe 28 and the tubular cover 56.
[0027] While the present invention has been described in
conjunction with a specific embodiment, it is understood that many
alternatives, modifications and variations will be apparent to
those skilled in the art in light of the foregoing description. For
example, although the vehicle 10 shown in FIG. 1 is a tractor, it
is likewise feasible for the assembly 20 according to the invention
to be used with any other desired diesel-engined motor vehicles. In
addition, it may also be used in stationary applications, such as
for example a diesel-engined power generator or the like.
Accordingly, this invention is intended to embrace all such
alternatives, modifications and variations which fall within the
spirit and scope of the appended claims.
* * * * *