U.S. patent application number 11/608994 was filed with the patent office on 2008-06-05 for exhaust system.
This patent application is currently assigned to DOLMAR GMBH. Invention is credited to Christian Kellermann.
Application Number | 20080127641 11/608994 |
Document ID | / |
Family ID | 37903518 |
Filed Date | 2008-06-05 |
United States Patent
Application |
20080127641 |
Kind Code |
A1 |
Kellermann; Christian |
June 5, 2008 |
EXHAUST SYSTEM
Abstract
In order to provide an exhaust system for a combustion engine
with an outer casing in which hot exhaust gas is introduced through
an exhaust inlet and discharged from an exhaust outlet wherein the
exhaust outlet is of a tubular, more preferably having a circular
or oval cross section design which, in a simple way, preferably
effectively lowers the exhaust gas temperature in the exhaust
outlet it is proposed that arranged in the area of the tubular
exhaust outlet is an exhaust swirling device having at least one
guide blade through which the exhaust gas is deflected in the
exhaust outlet.
Inventors: |
Kellermann; Christian;
(Stapelfeld, DE) |
Correspondence
Address: |
KELLY LOWRY & KELLEY, LLP
6320 CANOGA AVENUE, SUITE 1650
WOODLAND HILLS
CA
91367
US
|
Assignee: |
DOLMAR GMBH
Hamburg
DE
|
Family ID: |
37903518 |
Appl. No.: |
11/608994 |
Filed: |
December 11, 2006 |
Current U.S.
Class: |
60/324 ;
181/227 |
Current CPC
Class: |
F01N 13/082 20130101;
F01N 13/002 20130101; F01N 2270/10 20130101; F01N 2590/06 20130101;
F01N 2270/02 20130101; F01N 13/1861 20130101 |
Class at
Publication: |
60/324 ;
181/227 |
International
Class: |
F01N 7/00 20060101
F01N007/00; F01N 1/08 20060101 F01N001/08 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 14, 2005 |
DE |
20 2005 019 662.2 |
Aug 29, 2006 |
DE |
20 2006 013 247.3 |
Claims
1. An exhaust system (100) for a combustion engine with an outer
casing (10), directed into which is hot exhaust gas (31) through an
exhaust inlet and discharged from an exhaust outlet (12) while the
exhaust outlet (12) is constructed in tube form, especially with a
circular or oval cross section, characterised in that in the area
of the tubular exhaust outlet (12) an exhaust swirling device (20)
having at least one guide blade (23) is arranged by means of which
the exhaust gas (31) is deflected in the exhaust outlet (12).
2. The exhaust system according to claim 1, characterised in that
the exhaust swirling device (20) is provided as an independent
component in the area of the exhaust outlet (12).
3. The exhaust system according to claim 1 characterised in that
the exhaust swirling device (20) is arranged in a separate casing
(21) more preferably in a casing (21) with a sectional circular or
oval cross section, where the casing (21) more preferably serves
for the attachment of the exhaust swirling device (20) in the area
of the tubular exhaust outlet (12).
4. The exhaust system according to claim 1 characterised in that
the exhaust swirling device (20) is arranged in the exhaust outlet
(12) such that a short pipe section, especially of the exhaust
outlet (12), additionally joins the exhaust swirling device (20)
before the exhaust gas (31) leaves the casing (10).
5. The exhaust system according to claim 1 in that the exhaust
swirling device (20) has a sheet metal design wherein more
preferably a part or the entire exhaust swirling device (20) can be
formed from the outer casing (10).
6. The exhaust system according to claim 1 characterised in that
the exhaust swirling device (20) has a casting more preferably a
precision casting.
7. The exhaust system according to claim 1 characterised in that
the entire exhaust gas (31) can be deflected by means of the guide
blade(s) (23) as a result of which swirling of the entire exhaust
gas (31) with the ambient air takes place.
8. The exhaust system according to claim 7, characterised in that a
fixed element is provided in the central cross sectional area of
the exhaust swirling device (20) to which the guide blade(s) (23)
can also be attached.
9. The exhaust system according to claim 1 characterised in that
only a part of the exhaust gas (31) can be deflected centrally by
means of the guide blade(s) (23) while an outer part of the exhaust
gas (31) can be influenced by the guide blade(s) (23) while an
inner part in the central cross sectional area passes through the
exhaust swirling device (20) without being influenced.
10. The exhaust system according to claim 9 characterised in that
the central cross sectional area of the exhaust swirling device
(20) is designed open.
11. The exhaust system according to claim 1 characterised in that a
triangular opening (26) through which a part of the exhaust gas
(31) is directed is provided for each guide blade (23).
12. The exhaust system according to claim 11 characterised in that
the exhaust gas (31) passes the guide blade(s) (23) first in flow
direction and is subsequently directed through the triangular
openings (26).
13. The exhaust system according to claim 1 characterised in that a
guide blade (23) has a circular segment type surface more
preferably constructed flat.
14. The exhaust system according to claim 1 characterised in that a
guide blade (23) is developed arch-shaped or wave-type.
15. The exhaust system according to claim 1 characterised in that
the approximate width (28) of a guide blade (23) corresponds to a
radius of the exhaust swirling device (20).
16. The exhaust system according to claim 1 characterised in that
all guide blades (23) are constructed symmetrically identical.
17. The exhaust system according to claim 1 characterised in that
the exhaust swirling device (20) discharges the exhaust gas (31)
largely tangentially to the longitudinal axis (27) of the exhaust
swirling device (20).
18. The exhaust system according to claim 1 characterised in that
the exhaust swirling device (20) discharges the exhaust gas (31)
largely radially to the longitudinal axis (27) of the exhaust
swirling device (20).
19. The exhaust system according to claim 1 characterised in that
the hot exhaust gas (31) is discharged from the exhaust outlet (12)
following treatment of the exhaust gas (31).
20. The exhaust system according to claim 1 characterised in that
at least one catalyst element for exhaust gas treatment is arranged
in the exhaust system.
21. The exhaust system according to claim 20 characterised in that
the catalyst element is arranged in a catalyst chamber (13) and the
exhaust gases (31) are directed from the catalyst chamber (13)
through an exhaust duct (15) to the exhaust swirling device (20)
before the exhaust gas (31) enters the environment through the
exhaust outlet (12).
22. The exhaust system according to claim 1 characterised in that
at least one spark protection screen is arranged before or in the
exhaust swirling device (20).
23. The exhaust system according to claim 1 characterised in that
an axial depression of the guide blades (23) comprises 5 to 70%
advantageously 10 to 50% and particularly advantageously 15 to 30%
of the diameter of the exhaust duct (12).
24. The exhaust system according to claim 1 characterised in that
the area of all openings (26) for a part flow of the exhaust gas
(31) is at least as large as the cross sectional area of the
exhaust outlet (1 2).
25. (canceled)
Description
TECHNICAL AREA
[0001] The present invention relates to an exhaust system for a
combustion engine with an outer casing in which hot exhaust gas is
introduced through an exhaust gas inlet. Such an exhaust system can
be used for a four-stroke or a two-stroke petrol engine. Since the
exhaust system itself is of a particularly compact design it can
also be utilised with hand-operated machines such as petrol engine
driven disc grinders, chainsaws, hedge clippers or similar. After
treatment of the exhaust gas within the exhaust system the exhaust
gas is discharged into the environment from the exhaust outlet. The
treatment of the exhaust gas can be a measure for sound absorption
of the exhaust gas noise, for pollutant reduction of the exhaust
gas or for cooling the exhaust gas or similar. In this way the
exhaust gas is treated by the exhaust system so that it is
subsequently discharged into the environment through the exhaust
outlet. The exhaust gas outlet in this case is designed in the
shape of a tube especially with a circular or oval cross
section.
PRIOR ART
[0002] Arranging an exhaust gas swirling device within an exhaust
system is generally known from the prior art. Here, these swirling
devices generally serve to extinguish glowing particles in the
combustion exhaust gas so that these are not discharged into the
environment through the exhaust gas outlet. For example DE-PS 948
210 discloses an exhaust system with a so-called cyclone winding or
arrangement. Here, brought about by the cyclone arrangement, the
exhaust gases are imparted rapid rotary motion as a result of which
the glowing particles present in the exhaust gas are squashed
against the inside of the exhaust system and quickly and safely
extinguished as a consequence. However, this cyclone is arranged
within the exhaust system, i.e. far upstream of the exhaust outlet,
so that the glowing particles can still be extinguished on the
inside of the exhaust system.
[0003] In addition it is known from the prior art that a long
exhaust gas duct is arranged for instance behind an exhaust element
to cool down the converted exhaust gases. Here, the exhaust gas
duct itself can serve as spark extinguisher in that it assumes a
zigzag type or arched course. As a rule, the hot exhaust gases are
then directly discharged from the exhaust duct into the open or the
environment. However, very high exhaust gas temperatures still
occur behind the exhaust outlet in this case.
Presentation of the Invention, Object, Solution, Advantages
[0004] Since the problem mentioned before mainly occurs with highly
compact exhaust systems, additional slits or openings are arranged
in the prior art in the outer casing of the exhaust system through
which fresh air is able to enter the exhaust system and is
redirected into the environment through the suction of the hot
combustion exhaust gas. Through the much cooler fresh air, mixing
of the hot exhaust gases with the cool ambient air occurs even
within the exhaust system. Injectors are also known which serve for
the cooling of the hot exhaust gas at the exhaust outlet but which
are little effective because of the pulsating flow of the exhaust
gas. As a consequence, very high temperatures still occur directly
after the exhaust gas outlet in the exhaust flow. These high
temperatures can pose a risk of injury especially in the case of
portable machines with combustion engines. They additionally pose a
fire hazard through the hot exhaust gases.
[0005] Before this background it is the object of the present
invention to provide a compact exhaust system which, in a simple
way, lowers the exhaust gas temperature in the exhaust outlet as
effectively as possible. Here, previously known designs of exhaust
systems are to be preferably used in order to achieve an economical
solution as well.
[0006] To solve this object an exhaust system with the features of
claim 1 is proposed.
[0007] With the exhaust system according to the invention it is
intended that an exhaust gas swirling device is arranged in the
area of the tubular exhaust outlet, having at least one guide blade
through which the exiting exhaust gas is deflected or swirled in
the exhaust outlet. The exhaust swirling device can be provided
before or in the exhaust outlet, or the exhaust swirling device
itself constitutes the exhaust outlet. It is further intended
through the invention that the exhaust swirling device has at least
one guide blade through which deflection or swirling of the exhaust
gas with the ambient air takes place. In this way it is possible to
transform a possible laminar flow of the exhaust gas into a
turbulent flow of the exiting exhaust gas which directly intermixes
with the cool ambient air after the exhaust outlet. By using the
exhaust gas swirling device according to the invention in the area
of the exhaust outlet the exhaust gas is rapidly rotated through
the existing guide blades. Owing to the centripetal force the
exhaust gas is greatly fanned out in the ambient air on leaving the
exhaust outlet. The exhaust gas can thus be mixed and cooled with
the ambient air over a considerably shorter distance. Consequently
the exhaust swirling device according to the invention does not
serve as spark extinguisher within an exhaust system as is known
from the prior art but the exhaust swirling device serves
exclusively for the reduction of the exhaust temperature downstream
of the exhaust outlet. Since, with the application intended here,
the exhaust swirling device itself only has a depth of a few
centimetres the demanded compact design of the exhaust system can
be realised. The exhaust swirling device can also be integrated in
already existing exhaust system designs. Greater depths are
possible if the requirement of compact design is not as great as
for instance with lawnmowers.
[0008] Additional advantageous designs of the exhaust system are
mentioned in Sub-claims 2-24.
[0009] To preferably achieve an uneconomical design of the exhaust
system and obtain simple assembly of the exhaust system it can be
designed that the exhaust swirling device is provided as an
independent component in the area of the exhaust outlet.
Consequently no major changes to the previous manufacture of the
known exhaust systems are necessary and the assembly of the exhaust
system is also hardly affected by the exhaust swirling device. As a
result, the exhaust swirling device can simply be inserted in the
planned exhaust outlet as an independent component. However, it
must be ensured that the exhaust swirling device is not forced from
the exhaust outlet by the hot exhaust gas flow. To this end, the
exhaust swirling device can be arranged positively and/or
non-positively in the exhaust outlet. Here it is conceivable to
attach the exhaust swirling device in the exhaust outlet using a
screw, rivet, welded, soldering and/or clamping connection or to
secure it in the exhaust outlet by way of a bayonet closure.
[0010] It has also proved to be practical to arrange the exhaust
swirling device in a separate casing. Thus, the exhaust swirling
device largely contains a casing and an insert having the guide
blade provided in the casing. The additional casing can be used for
securing the exhaust swirling device in the exhaust outlet while
the fastening possibilities mentioned in the previous paragraph can
be employed. To keep the flow resistance of the exhaust swirling
device as low as possible it is advisable to provide a circular
cross section for the casing of the exhaust swirling device.
Obviously the present invention is not however restricted to a
casing with a circular cross section so that oval or other kinds of
cross sectional areas can also be employed. To ensure that the
exhaust gas is transformed into a turbulent flow small projections
can be arranged on the inside of the casing. Likewise, the inside
of the casing can have a rough surface. In addition, the exhaust
swirling device can be arranged in the exhaust outlet such that a
short pipe section of the exhaust outlet joins the exhaust swirling
device before the exhaust gas leaves the casing or enters the
environment. This measure can be used to cause the ambient air to
be drawn into the exhaust outlet where it mixes with the outflowing
exhaust gas, in this way lowering the discharge temperature as a
whole before the exhaust gas finally leaves the casing of the
exhaust system.
[0011] In order to preferably utilise the entire cross sectional
area of the casing for the exhaust flow it is advisable to form a
small-area central mounting surface as a fixed element on which the
guide blade can be centrally attached. As a result, the entire
exhaust flow can be deflected or swirled through the guide blades
to effectively avoid temperature peaks in the exhaust flow. As an
option it is possible to omit the mentioned fixed element in form
of a central mounting surface to utilise the entire cross sectional
area of the casing for the complete exhaust flow whereby the guide
blades cannot be attached centrally. In this case the central cross
sectional area of the exhaust swirling device is of an open
design.
[0012] To achieve economical manufacture of the exhaust swirling
device a sheet metal design can be provided. Here, the casing as
well as the insert with the guide blades can consist of sheet
metal. These sheet metal designs can be manufactured through a deep
drawing method or another forming method. With this version it is
also possible to form the exhaust swirling device from the outer
casing, especially a casing shell of the exhaust system.
Consequently a connection of the exhaust swirling device with the
exhaust system can be omitted since these two components are of a
single piece and uniform material design. It is also conceivable to
form only the casing or the insert of the exhaust swirling device
from the outer casing of the exhaust system.
[0013] With another embodiment of the exhaust system it is
conceivable that the exhaust swirling device, especially its insert
with the guide blades, consists of a casting. Here it is practical
for the casting to be a precision casting. Although a casting is
more expensive in manufacture than a comparable sheet metal design
but the design freedom is greater so that for instance profiled
guide blades can be cast. Obviously the entire exhaust swirling
device, i.e. insert and casing, can be designed as one or several
casting.
[0014] With a particularly interesting further development of the
exhaust swirling device it is intended that a triangular opening be
provided for each guide blade through which a part of the exhaust
gas or the exhaust flow is directed. Here, the nth part of the
exhaust gas is generally directed via the nth guide blade through
the n th opening. Consequently two, three or several guide blades
can be present for the exhaust swirling device. Here, the exhaust
gas or a part of the exhaust gas first flows in the flow direction
along the guide blades in order to be subsequently directed into
the ambient air through the triangular opening. By using n guide
blades the exhaust flow is fanned out into n parts.
[0015] It is also conceivable that the guide blades have circular
segment shape surfaces which more preferably have one flat or flat
surfaces. When using n guide blades 360.degree./n circular arc
shaped surfaces will then be used for the guide blades. Likewise, a
guide blade can also have an arched wave-shaped or bent surface,
more preferably if this is designed as a short turbine-type or
propeller-type blade. As an option, the guide blades can also be
arranged in uneven distribution over the circumference of the
exhaust outlet, i.e. adjacent guide blades each can have different
angles relative to each another.
[0016] In order to preferably use the entire cross section of the
exhaust swirling device for the exhaust outlet it is practical that
the approximate width of a guide blade corresponds to a radius of
the exhaust swirling device. Thus, the flow resistance of the
exhaust swirling device can be clearly reduced. To this end the
central mounting of the guide blades, if available, should be of a
particularly space saving or small design. This mounting surface is
generally arranged around the centre of the exhaust swirling
device. Likewise, it is advisable to arrange all guide blades
symmetrically even around the centre point or the longitudinal axis
of the exhaust swirling device. In this way, it is then possible to
guarantee even and effective mixing of the exhaust gas with the
ambient air. However, the invention is not restricted to
symmetrical guide blades so that the individual guide blades can
also be further developed geometrically different.
[0017] In addition it is practical if the area of all openings for
a part flow of the exhaust gas is at least as large as the cross
sectional area of the exhaust outlet. Thus, there is no cross
sectional reduction which results in increased flow resistance.
Here, the passage area of an opening for a part flow of the exhaust
gas is largely connected also with the axial depression of the
relevant guide blade. While it can be determined that the greater
the area of the passage opening for the respective part flow of the
exhaust gas, the greater also the axial depression of the guide
blade. In an advantageous way, the axial depression of the guide
blade is 5-70%, particularly advantageous 10-50% and highly
advantageous 15-30% of the diameter of the exhaust duct. Through
this diameter-height ratio in the exhaust swirling device it is
possible to achieve an optimum flow of the exhaust gas. When using
a two-stroke engine the exhaust swirling device can also be
utilised to provide the necessary flow resistance for optimum
engine charging if applicable. In accordance with this, the exhaust
swirling device, especially its flow resistance, must be adjusted
to suit the combustion engine.
[0018] To achieve comprehensive swirling of the exhaust gas with
the ambient air it is practical that the exhaust swirling device
discharges the exhaust gas largely tangentially to its longitudinal
axis or helically. Since the exhaust gas is also forced out of the
exhaust outlet in the direction of the longitudinal axis (i.e.
axially) comprehensive three-dimensional mixing of the exhaust gas
with the ambient air also takes place. Consequently the exhaust gas
significantly cools down even at a short distance behind the
exhaust outlet whereby this distance amounts to a few centimetres.
It is also conceivable that the exhaust swirling device discharges
the exhaust gas largely radially to the longitudinal axis of the
exhaust swirling device. In this case, the same positive effects as
previously described occur as well. To discharge the exhaust gas
from the exhaust swirling device or the exhaust outlet as desired
the geometry of the guide blades must be suitably adapted. Here it
is advisable to arrange the guide surfaces similar to turbine
blades to impart the desired swirl to the exhaust gas. To this end,
the rotation-symmetrically arranged guide blades if applicable are
similar to an aircraft propeller having n propeller blades. In this
case, the individual propeller blades can be arranged obliquely to
the flow direction of the entering exhaust gas. Owing to the large
number of development possibilities, desired swirling of the
exhaust gas with the ambient air can be realised.
[0019] In addition, the exhaust system according to the invention
can be practically provided with at least one catalyst element for
exhaust treatment. By using one or several catalyst elements
retreatment of the exhaust gas with the (chemical) components
contained in the exhaust gas is made possible. In this case, the
existing hydrocarbons are converted into carbon dioxides and water
or carbon monoxides for instance with the help of the residual
oxygen content. However, since additional heat is liberated during
this chemical conversion process the already hot exhaust gases are
heated additionally. Thus it is further practical to pre-cool the
exhaust gases directed through the catalyst element by means of a
downstream exhaust duct even within the exhaust system. Here, the
sparks in the exhaust gas should be extinguished at the same time.
To this end an additional spark protection screen can be arranged
especially before or in the exhaust swirling device. This spark
protection screen serves to filter any remaining sparks from the
exhaust gas so that these do not enter the environment. With a
particularly simple design the spark protection screen can be
arranged directly before or after the guide blades and can be
easily replaced for maintenance purposes provided the exhaust
swirling device is arranged on the exhaust system or in the exhaust
outlet by means of a reversible non-permanent connection.
Consequently the spark protection screen can be replaced or
maintained directly when the exhaust swirling device is
disassembled.
[0020] In a particularly interesting embodiment of the exhaust
system it can be provided that the catalyst element is arranged in
a catalyst chamber and the exhaust gases directed from the catalyst
chamber are directed through an exhaust duct to the exhaust
swirling device before the exhaust gas enters the environment
through the exhaust outlet. In addition, it is possible that the
spark protection screen already described is employed between the
exhaust duct and the exhaust swirling device. Such an exhaust
system according to the invention is not only of a compact design
but also satisfies the legal environmental regulations.
[0021] In addition, the invention is also aims at an exhaust
swirling device according to claim 25. This exhaust swirling device
has the characteristics from any of the claims 1 to 24.
SHORT DESCRIPTION OF THE DRAWINGS
[0022] Different embodiment examples of the inventions are
described in more detail by means of the enclosed drawings. It
shows in purely schematic representation:
[0023] FIG. 1 in three-dimensional view an exhaust system with an
exhaust swirling device according to the invention having five
propeller-type guide surfaces,
[0024] FIG. 2 in three dimensional exploded view a similar exhaust
system according to the invention--as in FIG. 1--with an exhaust
swirling device with four guide blades,
[0025] FIG. 3 in a diagram-type view an exhaust swirling device
with five propeller-type guide blades,
[0026] FIG. 4a, b, c in three different three-dimensional views an
insert for an exhaust swirling device having a total of four flat
and circular segment shaped guide blades,
[0027] FIG. 5a, b a further insert for an exhaust swirling device
also having four flat and circular segment shaped guide blades
however, of open design in the central cross sectional area,
and
[0028] FIG. 6a to e another version for an exhaust swirling device
in various views where the exhaust swirling device is partially
formed from the exhaust system, and
[0029] FIG. 7a to d in various views an exhaust system with the
exhaust swirling device from FIGS. 6a to 6e.
BEST WAY TO PERFORM THE INVENTION
[0030] FIG. 1 shows an exhaust system 100 according to the
invention in three-dimensional representation. Here, the exhaust
system 100 has an exhaust swirling device 20 arranged in the
exhaust outlet 12. This exhaust outlet 12 is located in an upper
casing shell 11 which, together with an outer casing shell 11,
forms the outer casing 10. The two lower and upper casing shells 11
can be connected with each other gas tight through a welded
connection, flanging or through the fasteners 19 shown. No exhaust
inlet is shown in FIG. 1 as a result of which the exhaust flow 31
is able to directly enter the exhaust system 100 from a cylinder of
the combustion engine. As can be seen however an exhaust swirling
device 20 is employed which has a total of 5 propeller-type guide
blades 23 while the respective guide blades are arranged obliquely
relative to the entering exhaust flow. As a result, the exiting
exhaust flow 31 is imparted a swirl through which the exhaust gas
31 is swirled or mixed with the ambient air directly behind the
exhaust outlet 12. In order to preferably avoid causing any flow
losses through the additionally employed exhaust swirling device 20
the individual guide blades 23 reach from the centre point 27,
which also forms the longitudinal axis of the exhaust swirling
device, to the circular inner surface of the exhaust duct 15.
Consequently the entire cross sectional area of the exhaust
swirling device 20 or the exhaust outlet 12 is utilised for
swirling the exhaust flow 31. By means of this it is possible to
avoid a laminar flow in the exhaust flow 31. This causes optimum
swirling of the exhaust gas directly after discharge from the
exhaust outlet 12.
[0031] FIG. 2 shows another exhaust system 100 according to the
invention where an exhaust swirling device 20 is likewise provided
in the exhaust outlet 12. This exhaust swirling device 20 mainly
contains a separate casing 21 and an insert 22 provided in the
casing 21 on which the guide blades 23 are arranged. Consequently
the exhaust swirling device 20 is constructed of two parts. As a
result, economical manufacture of the exhaust swirling device 20
can be achieved. Assembly of the exhaust swirling device 20 is also
simplified through this modular construction of the exhaust system
100. In addition, the exhaust system 100 has a catalyst element
(not shown) which is arranged within a catalyst chamber 13. An
exhaust duct 15 starts from the catalyst chamber 13 which is of a
meander-type design and terminates at the exhaust swirling device
20. Between the exhaust duct 15 and the exhaust swirling device 20
at least one spark protection screen can be additionally arranged.
In order to bring about an easy further development of the catalyst
chamber 13 and the exhaust duct 15, two chamber halves 14 are
provided which simultaneously form the catalyst chamber 13 and the
exhaust duct 15. These two chamber halves 14 are an upper and lower
chamber half 14 which themselves can consist of formed sheet metal
parts. These two chamber halves 14 are held approximately centrally
in the exhaust system 100 through spacers 17. To join the upper
chamber half 14 with the lower chamber half 14 additional fasteners
19, consisting of a screw nut connection, can be provided. It is
also conceivable that the two chamber halves 14 are joined to each
other through flanging over of their edge areas. When using
additional fasteners 19 it is advantageous to also join the exhaust
swirling device 20 or its casing 21 with the chamber halves 14. To
this end, openings 30 are provided in the casing 21 of the exhaust
swirling device 20 which are provided congruently with additional
openings 30 in the chamber halves 14.
[0032] To securely mount the insert 22 in the casing 21 of the
exhaust swirling device 20 it can be provided positively and/or
non-positively in the casing 21. It is also conceivable to jam the
insert 22 between the edge of the exhaust outlet 12 and the
swirling device casing 21. With a special version the insert 22 can
even be arranged so that it can rotate in casing 21.
[0033] In addition, a flow plate 16 with openings for exhaust gas
passage is provided with the exhaust system 100 from FIG. 2 below
the catalyst chamber 13. Thus this flow plate 16 is arranged
between the lower chamber half 14 and the lower casing shell 11. A
flange disc 18 can also be present between the flow plate 16 and
the lower casing shell 11.
[0034] FIG. 3 shows an exhaust swirling device 20 in
three-dimensional representation. With this exhaust swirling device
20 the casing 21 consists of a formed sheet metal part. In casing
21, the insert 22 with a total of five propeller-type guide blades
23 is arranged. These guide blades 23 have a circular segment type
outline while the circular segments roughly form an approximate
angle of 72.degree. (360.degree./5=72.degree., since five guide
blades). The surfaces of the guide blades 23 are arranged obliquely
or tilted relative to the flow direction of the entering exhaust
flow 31. The width 28 of the guide blades 23 largely runs from the
centre 27, which is designed as a fixed element, to the circular or
oval edge of the cylinder-type insert 22. The centre point 27 or
the longitudinal axis 27 is formed by a five-star closed surface
from which the five guide blades 23 radially originate or meet. It
is also conceivable instead of the closed central surface for
instance to employ a pipe or a continuous cylinder from the outer
edge of which the guide blades 23 originate radially. This central
cross sectional area can also be of an open design as will still be
described in the following.
[0035] As can be seen in FIG. 3 the exhaust flow 31 is introduced
into the exhaust swirling device 20 through the lateral opening 29.
The exhaust flow 31 is then deflected through the casing 21 to
impinge on the insert 22 with the guide blades 23. Here, at least
one spark protection screen can be additionally employed in the
casing 21. This spark protection screen can be arranged and
attached between the casing 21 and the upper chamber half 14. The
exhaust swirling device 20 also has a short pipe section behind the
guide blades 23 which can either be formed by the exhaust swirling
device 20, more preferably the insert 22, or by the tubular exhaust
outlet 12.
[0036] FIGS. 4a, b and c show an exemplary embodiment for an insert
22 of the exhaust swirling device 20 in three dimensional
representation. Here, the individual FIGS. 4a, b and c each show
different views of the same three-dimensional element 22. To
illustrate the operation of the exhaust swirling device 20 or the
insert 22 and the guide blades 23 arranged on it, the exhaust flow
31 is shown as an example in bold arrows.
[0037] FIG. 4a shows the insert 22 largely from its front 24. Here,
the front 24 meets the exhaust flow 31. This exhaust flow 31 now
impinges on the circular segment shaped guide blades 23 which run
obliquely to the back or axially to the back. In order to
preferably achieve a stable attachment of the guide blades 23 a
cross is provided as a fixed element in the front 24. A side of the
guide blade 23 originates from each of the sides of the cross. This
side determines the width 28 of the guide blade 23. The width 28
largely corresponds to the radius of the cylinder shaped insert 22
or the circular casing 21. Once the exhaust gas 31 impinges on the
guide blades 23 directed obliquely to the back it is directed
tangentially to the longitudinal axis 27 through triangular
openings 26 by the flat guide surfaces. A triangular opening 26
each is provided at the end of the open side of the guide blade 23.
Consequently 4 triangular openings 26 are also provided for the
four guide blades 23. The triangular opening is formed, on the one
hand, by the unsecured side of the guide blade 23 and, on the other
hand, by a side of the already described fixed cross on the front
24 and a side of the circular edge of the insert 22 originating
from this and largely arranged orthogonally.
[0038] FIG. 4b shows the same insert 22 from FIG. 4a in three
dimensional side view. The circular segment type guide surface 23
is clearly visible here which, in the present case, consists of a
90.degree. circular arc segment (quarter circular arc). Also
clearly visible is the triangular opening 26 through which the
exhaust gas 31 deflected on the guide blade 23 is forced so that it
can exit from the insert 22 or the exhaust outlet 12 with the swirl
imparted. This swirl of the exhaust flow 31 is represented as an
example by the two arrows 31. Obviously this exhaust flow can also
be generated further radially outward. Through the number n of the
guide blades 23 and the design of the individual guide blades 23
proper, direct influence can be exercised on the desired swirl of
the exhaust flow 31.
[0039] The present insert 22 consists of a shaped sheet metal part
which itself can be produced economically. To increase the lifespan
of this insert 22 a special alloy can be used for the sheet metal.
Stainless steel sheet can also be used. It is also conceivable to
provide the insert 22 with a surface coating through which the
service life or lifespan of the insert 22 can be extended.
[0040] FIG. 4c shows the already known insert 22 from FIGS. 4a, b.
However, this time the back 25 of the insert 22 is shown in
particular. Here, the exhaust gas 31 impinging on the front 24 is
directed to the four guide blades 23 and, through these, through
the four triangular openings 26 through the insert 22 proper.
Through the four guide blades 23 the exhaust flow 31 is subdivided
into a total of four part flows. These exhaust part flows exit
tangentially or radially to the longitudinal axis 27 from the
triangular openings 26. Consequently the exhaust flow 31 has been
imparted the desired swirl through the guide blade 23 so that
following its discharge from the exhaust outlet 12 it can directly
intermix with the ambient air.
[0041] Another insert 22 for an exhaust swirling device 20 is shown
in the FIGS. 5a, b. This insert 22 also has four guide blades 23.
The essential difference to insert 22 from the FIGS. 4a, b, c
consists in that here the guide blades 23 are not attached in the
central cross sectional area. Consequently the central cross
sectional area around the centre point 27 or the longitudinal axis
27 is designed open since a fixed element has been omitted. Thus
the entire cross sectional area is open for the flow of the exhaust
gas 31. However, as a result, the outer part of the exhaust gas 31
is deflected by the guide blades 23 to a greater extent than the
inner part of the exhaust gas 31, which is able to pass through the
(cross-shaped) opening 26 of the exhaust swirling device 20 more or
less unaffected. Depending on the approach flow velocity of the
exhaust gas 31, swirling of the inner part of the exhaust gas 31
can nevertheless take place since this part can be dragged along by
the outer part of the exhaust gas 31. This is an indirect
deflection or swirling of the inner part.
[0042] As is evident from FIG. 5a, showing the insert 22 largely
from its front 24, the insert 22 meets the exhaust gas 31 flow at
its front 24 so that the exhaust gas 31 flows mixed and/or swirled
from the insert 22 at the back 25.
[0043] In contrast with FIG. 5a the insert 22 is largely shown from
its back in FIG. 5b. Here, the short pipe section of the insert 22
is particularly clearly visible behind the guide blades 23. This
short pipe section in the present case has a circular cross
section. The individual guide blades 23 in this case are only
attached to the circular outer wall of the insert 22. Also clearly
visible is the cross-shaped opening 26 in the central cross
sectional area of the insert 22. In addition it is also visible how
the exiting exhaust gas 31 is initially conducted in the short pipe
section of the insert 22 before it is finally able to leave the
exhaust outlet 12 into the ambient air.
[0044] Depending on the flow velocity of the exhaust flow 31,
suction can partly form in the area of the centre point 27 causing
the ambient air outside the exhaust system 100 to be centrally
drawn into the exhaust outlet 12 or the insert 22. Thus mixing of
the exiting exhaust gases within the exhaust outlet 12 already
occurs. To further enforce this suction it is advisable to conduct
the deflected or outwardly directed exhaust flows 31 within a short
pipe section so that the suction effect forming in the area of the
centre point 27 is amplified.
[0045] The inserts 22 shown from the FIGS. 4a, b, c as well as 5a,
b can--as already mentioned--be designed as a formed sheet metal
part. However, the insert 22 can also be designed as a casting,
especially a precision casting. This casting can also be surface
coated additionally. Obviously it is also conceivable that the
exhaust swirling device 20 can be developed as a single part from a
casing 21 and an insert 22 with the corresponding guide blades 23
so that the casing 21 and the insert 22 form one part or piece and
are more preferably developed with uniform material.
[0046] FIGS. 6a to e show another exhaust swirling device 20 where
the casing 21 and the insert 22 are developed as a single-part. The
special feature of this exhaust swirling device 20 is that the
exhaust swirling device 20 entirely or partially can be formed from
a casing shell 11 or the outer casing 10 of the exhaust system 100.
To obtain a particularly economical and simple design a further
attachment 11a can be used in the area of the exhaust outlet 12.
Here, this attachment plate 11a can be attached to the outer casing
by way of welded, riveting, screw or soldering connections. With
this version it is conceivable to arrange the already described
spark protection screen between the guide blades 23 and the
additional attachment plate 11a. Obviously the spark protection
screen can also be arranged upstream of the guide blades 23.
[0047] FIG. 6a shows a front view of an exhaust swirling device 20
formed from the outer casing 10. Here, the guide blades 23 of the
exhaust swirling device 20 are visible through the exhaust outlet
12. These guide blades 23 are formed from the outer casing 10
through a deep drawing or other forming method. This forming step
for the exhaust swirling device 20 can take place directly when
forming the outer casing 10 into the casing shell 11. Consequently
no additional manufacturing step is required as a result of which
significant cost saving is possible. In addition, the
diameter-height ratio in the exhaust swirling device 20 can also be
determined through the axial depression of the guide blades 23.
[0048] FIG. 6b represents the section I-I through the FIG. 6a. Here
it becomes clear that the casing 21 of the exhaust swirling device
20 is a one-piece development for the insert 22 of the exhaust
swirling device. Both the casing 21 and the insert 22 are formed by
the outer casing 10 in this case. The advantage with this version
consists in that fewer components and consequently fewer sealing
points are present. However it must be mentioned that the exhaust
swirling device 20 from the FIGS. 6a to e can also consist of
additional sheet metal parts which, in the area of the exhaust
outlet 12, are mounted to the outer casing 10.
[0049] FIG. 6c shows a rear view of the exhaust swirling device 20
from FIGS. 6a and b. It is clearly visible that the four guide
blades 23 have been shaped segment-type from the outer casing 10.
However, during this forming process a star-shaped centre point 27
has been left in place. Obviously it is also conceivable to omit
this star-shaped centre point 27 during forming.
[0050] FIGS. 6d and 6e show a three dimensional view of the exhaust
swirling device 20. Here, the triangular opening 26 after the guide
blades 23 is visible in both figures. With this present version the
exhaust swirling device 20, the area of all openings 26 for a part
flow of the exhaust gas 31 is smaller than the cross sectional area
of the exhaust outlet 12. Thus a cross sectional reduction in the
exhaust swirling device results. Provided that the guide surfaces
23 are formed lower, i.e. with a greater axial depth from the outer
casing 10, the total area of all openings 26 can increase.
[0051] FIGS. 7a to d show another version of the exhaust system 100
with an exhaust swirling device 20 from FIGS. 6a to e in various
views.
[0052] FIGS. 7a and 7b show a three dimensional view of the outside
of the exhaust system 100. It can be clearly seen that the exhaust
swirling device 20 was partly formed from the outer casing 10,
especially the casing shell 11. An attachment plate 11a is
additionally used in the area of the exhaust outlet 12 as a result
of which the actual tubular exhaust outlet 12 is formed.
[0053] FIG. 7c shows a section II-II through FIG. 7b. This
sectional drawing explains that the exhaust swirling device 20 was
formed from the casing half 11. The additional attachment plate 11a
is also visible.
[0054] FIG. 7d shows a schematic exploded view of the outer parts
of the exhaust system 100. This view also makes it clear that the
exhaust swirling device 20 with its guide blades 23 and the
respective openings 26 were formed from the casing half 11.
Likewise it becomes clear that a spark protection screen can be
arranged between the guide blades 23 and the separate attachment
plate 11a. This spark protection screen could then also be held in
place through the attachment of the attachment plate 11a.
[0055] Finally it must be mentioned that the technical features
described above can be used for the exhaust system 100 or the
exhaust swirling device 20 according to the invention individually
or in any combination provided they are not explicitly mutually
exclusive.
LIST OF REFERENCE NUMBERS
[0056] 100 Exhaust system
[0057] 10 Outer casing
[0058] 11 Casing shell
[0059] 11a Attachment
[0060] 12 Exhaust outlet in 11
[0061] 13 Catalyst chamber
[0062] 14 Chamber half
[0063] 15 Exhaust duct
[0064] 16 Flow plate (with openings)
[0065] 17 Spacer
[0066] 18 Flange disc
[0067] 19 Fastener
[0068] 20 Exhaust swirling device
[0069] 21 Casing of 20
[0070] 22 Insert of 20
[0071] 23 Guide blade
[0072] 24 Front of 22
[0073] 25 Back of 22
[0074] 26 Opening for exhaust flow
[0075] 27 Centre point/longitudinal axis of 20 and 22
[0076] 28 Width of 23
[0077] 29 Entry opening for exhaust flow
[0078] 30 Opening for fastener
[0079] 31 Arrow for exhaust flow
* * * * *