U.S. patent application number 13/278517 was filed with the patent office on 2012-04-26 for arrangement and method for treatment of exahust gases.
This patent application is currently assigned to VOLVO CAR CORPORATION. Invention is credited to Peter Sandberg, Marie Stenfeldt.
Application Number | 20120096838 13/278517 |
Document ID | / |
Family ID | 43543754 |
Filed Date | 2012-04-26 |
United States Patent
Application |
20120096838 |
Kind Code |
A1 |
Sandberg; Peter ; et
al. |
April 26, 2012 |
ARRANGEMENT AND METHOD FOR TREATMENT OF EXAHUST GASES
Abstract
An exhaust gas treatment arrangement and a method thereof is
contemplated for treating exhaust gases flowing along a flow path
in an exhaust pipe system. The arrangement comprises a supply
element being in communication with a source comprising an ammonia
gas. The supply element comprises at least two discharge apertures
being adapted to communicate with the flow path such that the
ammonia gas may be dispersible from the discharge apertures into
the exhaust gases in the flow path in at least two discharge
directions.
Inventors: |
Sandberg; Peter; (Goeteborg,
SE) ; Stenfeldt; Marie; (Goeteborg, SE) |
Assignee: |
VOLVO CAR CORPORATION
Goteborg
SE
|
Family ID: |
43543754 |
Appl. No.: |
13/278517 |
Filed: |
October 21, 2011 |
Current U.S.
Class: |
60/274 ;
60/287 |
Current CPC
Class: |
Y02T 10/12 20130101;
F01N 2610/02 20130101; F01N 2610/1453 20130101; B01F 5/0463
20130101; B01F 3/04049 20130101; F01N 13/0097 20140603; F01N
2610/06 20130101; B01F 5/0466 20130101; B01F 5/048 20130101; Y02T
10/24 20130101; F01N 3/2066 20130101 |
Class at
Publication: |
60/274 ;
60/287 |
International
Class: |
F01N 3/24 20060101
F01N003/24; F01N 3/20 20060101 F01N003/20 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 22, 2010 |
EP |
10188558.0 |
Claims
1. An exhaust gas treatment arrangement for treating exhaust gases
flowing along a flow path in an exhaust pipe system, the
arrangement comprising: a supply element being in communication
with a source comprising an ammonia gas, said supply element
comprising at least two discharge apertures being adapted to
communicate with the flow path such that the ammonia gas is
dispersible from the discharge apertures into the exhaust gases in
the flow path in at least two discharge directions.
2. The arrangement according to claim 1, wherein the supply element
is adapted to be arranged on an outside of said exhaust pipe
system.
3. The arrangement according to claim 1, wherein the supply element
is adapted to be arranged in said exhaust pipe system.
4. The arrangement according to claim 1, wherein the supply element
is ring-shaped.
5. The arrangement according to claim 1, wherein the supply element
is adapted to extend across said flow path.
6. The arrangement according to claim 1, wherein each discharge
aperture comprises at least one of an opening, a spray nozzle and a
discharge head.
7. The arrangement according to claim 1, further comprising a
mixing unit for mixing air with the ammonia gas before said ammonia
gas is dispersed into the exhaust gases.
8. An exhaust pipe system comprising: an exhaust pipe; and a supply
element being in communication with a source comprising an ammonia
gas, wherein the supply element via at least one gas inlet through
a wall element in the exhaust pipe system leads the ammonia gas
into said flow path.
9. The exhaust pipe system according to claim 8, wherein the supply
element comprises at least two discharge apertures being adapted to
communicate with the flow path such that the ammonia gas is
dispersible from the discharge apertures into the exhaust gases in
the flow path in at least two discharge directions
10. The exhaust pipe system according to claim 9, further
comprising a catalytic converter having a first substrate and a
second substrate arranged in said flow path between an inlet and an
outlet of said catalytic converter, said second substrate being
arranged upstream of said first substrate, wherein said discharge
apertures are arranged in the flow path between said first
substrate and said second substrate.
11. The exhaust pipe system according to claim 10, wherein the
catalytic converter comprises a SCR catalytic converter or a SCR
coated substrate.
12. The exhaust pipe system according to claim 9, wherein the
discharge apertures with respect to each other, seen in a
cross-section in the flow path, have a symmetrical arrangement in
the flow path.
13. The exhaust pipe system according to claim 12, wherein at least
a first plurality of the discharge apertures with respect to each
other, seen in a cross-section in the flow path, cause the ammonia
gas to discharge towards a center of the flow path.
14. The exhaust pipe system according to claim 12, wherein at least
a second plurality of the discharge apertures with respect to each
other, seen in a cross-section in the flow path, cause the ammonia
gas to discharge away from the center towards a perimeter of the
flow path.
15. The exhaust pipe system according to claim 9, wherein the
discharge apertures with respect to each other, seen in a
cross-section in the flow path, cause the ammonia gas to discharge
away from a center towards a perimeter of the flow path.
16. The exhaust pipe system according to claim 9, wherein the
discharge apertures with respect to each other, seen in a
cross-section in the flow path, have a first number of discharge
apertures diametrically opposed to a second number of discharge
apertures, the first number of discharge apertures causing the
ammonia gas to discharge in a direction diametrically opposed to
the second number of discharge apertures.
17. A method of treating exhaust gases flowing along a flow path in
an exhaust pipe system comprising: discharging ammonia gas into
said flow path from at least two discharge apertures in at least
two discharge directions.
18. The method according to claim 17, further comprising
discharging the ammonia gas symmetrically in three discharge
directions.
19. The method according to claim 17, further comprising
discharging the ammonia gas into said flow path upstream of a first
substrate in a catalytic converter.
20. The method according to claim 17, further comprising mixing the
ammonia gas with air prior to discharging the ammonia gas into said
flow path.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims foreign priority benefits under 35
U.S.C. .sctn.119(a)-(d) to EP 10188558.0, filed Oct. 22, 2010, the
disclosure of which is hereby incorporated by reference in its
entirety.
TECHNICAL FIELD
[0002] The present invention relates to an exhaust gas treatment
arrangement and method, such as but not necessarily limited to an
arrangement and method for treating exhaust gases flowing along a
flow path in an exhaust pipe system.
BACKGROUND
[0003] Combustion engines in vehicles produces exhaust gases when
running. The exhaust gases produced may comprise particles or
elements which may be harmful to humans, animals and/or nature.
Over the years, different attempts have been made to reduce the
amount of these harmful particles or elements coming from the
exhaust gases. It has been found that a catalytic converter
arranged in an exhaust pipe system for treatment of the exhaust
gases may result in a reduced level of nitrogen oxides, NOx. A
further improved reduction of NOx in the exhaust gases has been
achieved by mixing a reductant into the exhaust gases prior to
treatment of the exhaust gases in the catalytic converter. An even
further improvement has been achieved when a reductant of e.g.
urea, being converted into an ammonia gas, was introduced into the
exhaust pipe system and mixed with the flowing exhaust gases.
[0004] US 2007/0048204 A1 discloses a technique having urea
introduced into an exhaust pipe system to reduce emission of NOx in
the exhaust gases upon treatment in a catalytic converter. Prior to
entering into the exhaust pipe system, the urea in US 2007/0048204
A1 is pressurized and heated. Upon entering into the exhaust pipe
system containing exhaust gases, upstream the catalytic converter,
the pressurized and heated urea is converted into ammonia gas. The
conversion and mixing of the ammonia gas takes place in a mixing
part of the exhaust pipe system upstream the catalytic converter.
The mixing part has a length which is primarily dedicated to the
mixing of the reductant into the exhaust gases. After the mixing,
the mixture of ammonia gas and exhaust gases enters into the
catalytic converter. Inside the catalytic converter the ammonia gas
reacts with the exhaust gases in a chemical process resulting in a
reduction of the level of NOx in the exhaust gases.
[0005] A drawback with prior art technology is that the length of
the mixing part may determine, or affect, how well the reductant is
mixed with the exhaust gases inside the exhaust pipe system, hence,
how effective the system is in reducing the emission of NOx. If the
mixing part is too short then a low conversion of NOx may be
achieved. If the mixing part is too short then not enough of urea
will be able to converse into ammonia gas. The length of the mixing
part in the prior art solution has to satisfy two conflicting
requirements:
[0006] a) to be sufficiently long in order for the ammonia gas to
be converted and mixed into the exhaust gases prior to entering
into the catalytic converter. Being in liquid phase, the urea that
hasn't been converted into ammonia gas may have a low probability
of being mixed with the exhaust gases, hence to reduce their NOx
level.
[0007] b) to be as short as possible to reduce the total length of
the exhaust gas system and simultaneously be sufficiently long in
order to fulfill requirement a).
SUMMARY
[0008] An object of the invention is to provide a compact exhaust
pipe system whose length is not dependent on the mixing length
required to mix a reductant with exhaust gases prior to the exhaust
gases entering into a catalytic converter.
[0009] Another object of the invention is to provide an exhaust gas
treatment arrangement where a reductant does not need to go through
a process of phase change upon being introduced into the exhaust
pipe system may be used.
[0010] Another object of the invention is to reduce, or ameliorate,
at least some of the drawbacks in known technology, or to provide
useful alternatives thereto.
[0011] This and other objects are achieved by the exhaust gas
treatment arrangement contemplated by the present invention.
[0012] As such, the present invention relates to an exhaust gas
treatment arrangement for treating exhaust gases flowing along a
flow path in an exhaust pipe system. The arrangement comprises a
supply element being in communication with a source comprising
ammonia gas. The supply element comprises at least two discharge
apertures being adapted to communicate with the flow path such that
the ammonia gas is dispersible from the discharge apertures into
the exhaust gases in the flow path in at least two discharge
directions.
[0013] An exhaust pipe system with the arrangement of the present
invention may be constructed comprising a short, reduced or almost
eliminated mixing length. The shortened exhaust pipe system thus
provides as an advantage that the exhaust pipe system may be made
using less material. This reduced use of material may further have
a positive impact of the production cost, which thus may be
decreased. Another advantage caused by the reduced mixing length is
that a higher temperature of the exhaust gases entering into the
catalytic converter may be achieved. This because the flow path for
the exhaust gases from the combustion engine to the catalytic
converter is shortened. A high temperature of the exhaust gases is
desirable as they enter into the catalytic converter. A high
temperature of the exhaust gases has proven to improve the chemical
reaction between the reductant and the exhaust gases in the
catalytic converter, and thus to reduce the level of NOx in the
exhaust gases.
[0014] Another advantage in accordance with the invention is that
no mixing device has to be present in the flow path to achieve
sufficient mixing between of the reductant into the exhaust gases.
Another further advantage is that the mixing and distribution of
the reductant into the flow path may be achieved without
backpressure losses.
[0015] According to the present invention, the supply element may
be adapted to be arranged on an outside of said exhaust pipe
system. Being arranged on the outside allows the supply element to
communicate with e.g. the source comprising the reductant. A flow
of reductant from the source may then be provided to the flow path
in the exhaust pipe system.
[0016] According to the present invention, the supply element may
be adapted to be arranged within said exhaust pipe system. The
arrangement within said exhaust pipe may be achieved by including
an internal element of the supply element within said exhaust pipe
for dispersing, e.g. spraying, the reductant directly into the flow
path of exhaust gases.
[0017] According to the present invention, the supply element may
be ring-shaped. The ring-shaped element may be uniformly arranged
in the flow path having a substantially circular cross-section. The
ring-shaped element may comprise discharge apertures which are
uniformly and symmetrically arranged along the ring shaped element.
The reductant is uniformly dispersed into the flow path via the
uniformly and symmetrically arranged discharge apertures.
[0018] According to the present invention, the supply element may
be adapted to extend across said flow path. Such extension may be
achieved by including a tube element in the supply element. The
tube element may extend symmetrically partly, or in full, across
the flow path. The tube element may comprise discharge apertures
which are uniformly and symmetrically arranged along the tube
element crossing the flow path. The reductant is arranged to be
uniformly dispersed into the flow path by the discharge apertures
of the tube element.
[0019] According to the present invention, each discharge aperture
may comprise an opening, a spray nozzle or a discharge head. The
reductant may be arranged to enter into the flow path uniformly as
a gas via the discharge apertures whereby a direct mix with the
exhaust gases may be achieved. An effect of using spray nozzles is
that the reductant may be dispersed as a stream in gas form, or
e.g. as small droplets, inside the flow path. As such, the
reductant entering may therefore mix directly with the exhaust
gases in the flow path.
[0020] According to the present invention, the arrangement may
further comprise a mixing unit for mixing air with the ammonia gas
before said ammonia gas is dispersed into the exhaust gases. The
air being mixed with the ammonia gas may e.g. be pressurized
assistant gas which may consist of air or other equivalent
alternatives to air. The ammonia gas adapted for being mixed into
the exhaust gases is the reductant for the process. Assistant gas
may be pressurized by e.g. a boost pressure, exhaust manifold
pressure, compressor or other means and or methods. Boost pressure
may be a preferred method as it in general is present in the
vehicles. Boost pressure may therefore be non expensive and fairly
easy to adapt for pressurizing the assistant gas. The volume of the
reductant to be used for dispersing into the exhaust gases may be
increased by mixing air, e.g. assistant gas, into the ammonia gas
prior to entry into the exhaust gases. The mixing effect is
improved when a large volume of reductant is introduced into the
exhaust gases. The mixing may further results in an improved
distribution of the ammonia gas with and against the substrates of
the catalytic converter. A low volume of reductant having a high
concentration of ammonia gas being mixed into the exhaust gases may
result in poor mixing compared to a large volume of reductant
having a lower concentration of ammonia gas introduced into the
exhaust gases. The reductant may be introduced into the flow path
under high pressure.
[0021] A second aspect of the present invention relates to an
exhaust pipe system comprising an exhaust pipe and an exhaust gas
treatment arrangement according to the first aspect of the present
invention. A supply element may lead ammonia gas into the exhaust
gases in the flow path via at least one gas inlet through a wall
element in the exhaust pipe system.
[0022] According to the second aspect of the present invention, the
system may comprise a catalytic converter having a first substrate
and a second substrate arranged in the exhaust gas flow path
between an inlet and an outlet of said catalytic converter. The
second substrate is arranged upstream of said first substrate, and
the discharge apertures are arranged in the flow path between said
first substrate and second substrate. A partial first cleaning of
the exhaust gases may take place at the second substrate when the
exhaust gases enter into the catalytic converter. After having
passed through the second substrate the exhaust gases may enter
into a space arranged in the flow path after the second substrate
and before the first substrate. The reductant may be introduced and
mixed into the exhaust gases flowing through the flow path in such
a space. The mixture of exhaust gases and reductant continues from
the space into the first substrate. In the first substrate the
mixture of exhaust gases and reductant reacts with the surface of
the first substrate resulting in a reduction of the NOx in the
exhaust gases.
[0023] The reductant in gas form, e.g. ammonia gas, may be
introduced or dispersed directly into the exhaust pipe system. This
has the effect that the mixing length, where the reductant may be
conversed from a liquid phase into a gaseous phase, therefore will
be superfluous. The shortening of the mixing length results in to a
reduction of the total distance between the combustion engine and
the catalytic converter. Such a reduction of the length of the
exhaust gas flow before entering the catalytic converter results in
an increased temperature of the exhaust gases. A high temperature
of the exhaust gases inside the catalytic converter has a positive
impact on the catalytic effect of the catalytic converter.
[0024] According to the second aspect of the present invention, the
discharge apertures may, with respect to each other seen in a
cross-section of the flow path, be arranged symmetrically in the
flow path. By spraying or introducing the reductant into the
exhaust gases from the cross sectionally symmetrically arranged
discharge apertures a uniform mixture between the exhaust gases and
reductant may be achieved.
[0025] According to the second aspect of the present invention, the
catalytic converter may comprise a Selective Catalytic Reduction
(SCR) catalytic converter or a SCR coated substrate. Further, the
catalytic converter may also comprise a particulate filter or
another substrate which comprises a SCR coating. A SCR catalytic
converter is a catalytic converter which is arranged for converting
nitrogen oxides, also referred to as NOx, into water, H2O, and
diatomic nitrogen, N2, by using a reductant which may be mixed with
the exhaust gases.
[0026] A third aspect of the present invention relates to a method
of treating exhaust gases flowing along a flow path in an exhaust
pipe system. The method comprises the step of discharging an
ammonia gas into said flow path from at least two discharge
apertures in at least two discharge directions.
[0027] According to the third aspect of the present invention, the
method comprises the step of discharging ammonia gas symmetrically
in three discharge directions. This has the effect that a rapid and
good mixture between the ammonia gas and the exhaust gas is
achieved.
[0028] According to the third aspect of the present invention, the
method comprises the step of discharging ammonia gas into said flow
path upstream of a first substrate in a catalytic converter. This
has the effect that the exhaust gases, which enter into the first
substrate, comprises a mixture of reductant.
[0029] According to the third aspect of the present invention, the
method comprises the step of mixing ammonia gas with air, e.g.
pressurized assistant gas, prior to discharging ammonia gas into
said flow path. A highly pressurized reductant gas may, upon
entering into the exhaust flow path via small openings in the
discharge aperture, generate a spray-like distribution of the
reductant gas into the exhaust gases.
BRIEF DESCRIPTION OF THE DRAWINGS
[0030] The present invention will hereinafter be explained in
greater detail by means of non-limiting examples and with
references and with reference to the appended drawings in
which:
[0031] FIG. 1 illustrates an exhaust gas treatment arrangement
being provided with an exhaust pipe system;
[0032] FIG. 2 illustrates a supply element having discharge
apertures arranged within a flow path;
[0033] FIG. 3 illustrates a supply element having discharge
apertures in accordance with FIG. 2 arranged between two
substrates;
[0034] FIG. 4 illustrates a supply element having discharge
apertures formed in a parallel tube element arranged between two
substrates;
[0035] FIG. 5 illustrates a supply element having discharge
apertures formed in a ring-shaped element arranged within a flow
path;
[0036] FIG. 6 illustrates a supply element having discharge
apertures formed in a flexible ring-shaped element arranged within
a flow path;
[0037] FIG. 7a illustrates, in a side view, a supply element having
discharge apertures formed in a tube element which partly extends
through a flow path;
[0038] FIG. 7b illustrates the supply element in accordance with
FIG. 7b in a view which is in and aligned with the flow path and
which outlets of the discharge apertures in the flow path form a
triangular pattern,
[0039] FIG. 7c illustrates the supply element in accordance with
FIG. 7b in a view which is in and aligned with the flow path and
which outlets of the discharge apertures in the flow path are
arranged along a diagonal across the flow path.
[0040] It should be noted that the appended drawings are not
necessarily drawn to scale and that the dimensions of some features
of the present invention may have been exaggerated for the sake of
clarity.
DETAILED DESCRIPTION
[0041] The invention will, in the following, be exemplified by
embodiments. It is to be understood, however, that the embodiments
are included in order to explain principles of the invention and
not to limit the scope of the invention defined by the appended
claims.
[0042] FIG. 1 illustrates an exhaust gas treatment arrangement (1)
for treating exhaust gases flowing along a flow path (2) in an
exhaust pipe system (3). The denomination "exhaust gas treatment
arrangement" will henceforth be equivalent to "arrangement". The
exhaust pipe system (3) is configured to be arranged in a vehicle
and connected to an engine or motor, e.g. a combustion engine, in
the vehicle. The flow path (2) extends through the exhaust pipe
system (3) from the engine towards an outlet at an end part of the
exhaust pipe system (3). The arrangement (1) comprises a supply
element (4). The supply element (4) may be in communication with a
source (5) comprising ammonia gas. The supply element (4) is a
pipe, or a conduit, through which pipe the ammonia may flow from
the source (5). The source (5) may be a container that is made such
that it may resist a high internal pressure. Further, the source
(5), container, may be made of such material whereby it may
withstand a possible reaction of the material, e.g. a corrosive
reaction, from a reductant being e.g. urea or ammonia contained
inside the source (5).
[0043] The exhaust pipe system (3) comprises the exhaust pipe (9)
or catalytic converter (12).
[0044] The supply element (4) is adapted to be arranged on an
outside of the exhaust pipe system (3). This because the supply
element (4), or part of the supply element (4), is configured to
either directly or indirectly connect with the source (5) which may
be arranged outside the flow path (2). The source (5) may in the
vehicle be arranged such that it may be filled, charged and/or
loaded with the reductant. The source (5) may further in the
vehicle be arranged such that the source (5) can be changed or
replaced if being e.g. damaged. Therefore, the supply element (4)
may be arranged on an outside of the flow path (2) and the supply
element (4) may thereafter connect the source (5) directly or
indirectly with the exhaust pipe system (3).
[0045] The supply element (4) is arranged with discharge apertures
(6a, 6b, 6c), see FIG. 2-7. The respective discharge aperture (6a,
6b, 6c) is arranged for discharging the reductant in a respective
discharge direction (7a, 7b, 7c) inside the exhaust pipe system (3)
in the flow path of the exhaust gases. This to ensure the reductant
to be well mixed with the exhaust gases flowing through the exhaust
pipe system (3).
[0046] The arrangement (1) comprises a mixing unit (8) for mixing
air with the ammonia gas before said ammonia gas is dispersed into
the exhaust gases. The mixing unit (8) is arranged such that it
comprises a connection communicating with the source (5). Further
comprises the mixing unit (8) an air supply (18). The air supply
(18) may be a unit providing air into the mixing unit (8). The
reductant, e.g. the ammonia gas, is in the mixing unit (8) mixed
with the air. The mixture of ammonia gas and air is then guided
through the supply channel (4) towards the exhaust pipe system (3).
The supply channel (4) is connected with the exhaust pipe system
(3) via a gas inlet (10). The gas inlet (10) may be arranged
against a wall element (11) of the exhaust pipe system (3). The
reductant may through said gas inlet (10) be directly lead or
streamed into the flow path (2), e.g. as a mist. The wall element
(11) may be a part of a surface of the exhaust pipe (9) being part
of the exhaust pipe system (3). The wall element (11) may also be a
part of a surface of a casing or shell of the catalytic converter
(12). The catalytic converter (12) may further be part of the
exhaust pipe system (3). The exhaust pipe (9) is in the exhaust
pipe system (3) arranged between the catalytic converter (12) and
the engine of the vehicle.
[0047] The catalytic converter (12) may comprise a first substrate
(13). The catalytic converter (12) may further comprise a second
substrate (14). A substrate in a catalytic converter is a block
being e.g. monolith and made of e.g. ceramic or stainless steel.
The block may be covered with e.g. a precious metal. The precious
metal may e.g. be platinum, palladium and/or rhodium. The block may
comprise a structure of fine channels. These channels may have a
surface which preferably may be fairly coarsed. A chemical reaction
will occur when the exhaust gases mixed with the reductant comes
into contact with the channels. The chemical reaction results in
that the NOx in the exhaust gases thus may be reduced.
[0048] The catalytic converter (12) in accordance with the
invention may comprise a diesel oxidated catalyst (DOC), diesel
particulate filter (DPF), selective catalytic converter (SCR) or a
SCR coated DPF. A SCR catalytic converter is a catalytic converter
which is adapted for converting nitrogen oxides, also referred to
as NOx, into water, H2O, diatomic nitrogen, N2, by using a
reductant.
[0049] The first and the second substrate (13, 14) may in the
catalytic converter (12) be arranged one block with a space (19)
between the substrates (13, 14) or in separate catalytic converter
blocks. If the wall element (11) in accordance with above is
configured to be the wall element of the catalytic converter (12),
then said gas inlet (10) may be arranged in the wall element (11)
of the catalytic converter (12). The gas inlet (10) may then
communicate with the space (19) inside the catalytic converter
(12).
[0050] The catalytic converter (12) comprises an inlet (15) and an
outlet (16). The inlet (15) is connected with the exhaust pipe (9)
whereby the exhaust gases may enter into the catalytic converter
(12). The substrates (13, 14) are arranged between said inlet and
outlet in the flow path (2) extending through the catalytic
converter (12). The second substrate (14) may be arranged upstream
of the first substrate (13) in the flow path (2).
[0051] In the flow path (2) after the catalytic converter (12) is
an exhaust box (17) arranged. The exhaust box (17) may also be
referred to as a muffler. The exhaust box (17) may be connected
with the catalytic converter (12) via a pipe member extending there
between. The exhaust box (17) may be a part of the exhaust pipe
system (3) whereby the flow path (2) therefore may be extending
through said exhaust box (17). When the exhaust gases have passed
through the exhaust box (17), the exhaust gases may via a passage
(24) leave the exhaust pipe system (3). The passage (24) may be
arranged in the exhaust box (17) as a hole or opening through which
the exhaust gases may exit after have passed through the exhaust
box (17). Alternatively, the passage (24) may be arranged at an end
part of a conduit member being connected with the hole or opening
of the exhaust box (17). The exhaust gases leaving the exhaust pipe
system (3) via the outlet may have reduced its content of NOx due
to the treatment achieved when flowing through the catalytic
converter (12).
[0052] In accordance with FIG. 1, the supply channel (4) is
connected with the mixing unit (8). The reductant may be mixed with
a pressurized gas, e.g. air, in the mixing unit (8). The reductant
flow towards the discharge apertures via the supply channel (4).
Any discharge apertures, in accordance with the invention, may be
used in combination with the mixing unit (8).
[0053] FIG. 2 illustrates a part of the exhaust pipe system (3)
having three discharge apertures (6a, 6b, 6c) arranged to provide a
discharge of the reductant into the flow path (2) from three
different locations in the flow path (2). Seen in a cross section
through the flow path (2), the located discharge apertures (6a, 6b,
6c) may be symmetrically arranged in the flow path (2) with respect
to each other. The part of the exhaust pipe system (3) illustrated
in accordance with FIG. 2 may hence be a part of the exhaust pipe
(9). Each discharge aperture (6a, 6b, 6c) is connected with the
supply channel (4). In accordance with the embodiment of FIG. 2 the
supply channel (4) comprises around the exhaust pipe (9) and/or the
flow path (2) an external ring element (20). The external ring
element (20) may extend outside and around the flow path (2). From
the ring element (20) extends discharge conduits (21a, 21b, 21c)
connecting the ring element (20) with the discharge apertures (6a,
6b, 6c) via the discharge conduits (21a, 21b, 21c). The reductant
may thereby flow to the discharge apertures (6a, 6b, 6c). Each
discharge aperture (6a, 6b, 6c) may consist of a spray nozzle or a
discharge head. The spray nozzle or discharge head may spray the
reductant into the flow path (2) in one or more discharge
directions (7a, 7b, 7c). The reductant may thus be dispersed from
the spray nozzle or spray head as a stream in a gas form, or e.g.
in small droplets, in to a volume inside the flow path (2). When
the reductant enters directly into the flow path from the nozzles
in gas form it may directly be mixed with the exhaust gases in the
flow path (2). The mixing length used in traditional exhaust gas
systems may therefore be limited in accordance with the
invention.
[0054] A discharge aperture (6a, 6b, 6c) may consist of a small
hole or opening in the exhaust pipe (9) or in the catalytic
converter. Via the small hole or opening may the reductant be
introduced into the flow path and mixed with the exhaust gases
therein.
[0055] The spray nozzles may be arranged with respect to each other
in the flow path (2) such that the respective discharge direction
(7a, 7b, 7c) or directions from each spray nozzle may be
symmetrically directed with respect to each discharge direction
(7a, 7b, 7c) of each spray nozzle.
[0056] In accordance with one embodiment as illustrated in FIG. 2,
the spray nozzles or discharge heads may be connected with each
other via an internal ring element (22). The internal ring element
(22) may support the locations, or positions, of the spray nozzles
or discharge heads inside the flow path (2). The internal ring
element (22) may further be arranged for functioning as a part of
the supply channel (4) whereby the reductant may be adapted to flow
therein and between the spray nozzles or discharge heads.
[0057] FIG. 3 illustrates an embodiment of the invention having the
discharge apertures (6a, 6b, 6c) symmetrically arranged such that a
symmetrical discharge of the reductant in to the flow path (2) may
be achieved. In accordance with the embodiment of FIG. 3 the
discharge apertures (6a, 6b, 6c) may be arranged in a space (19)
arranged between the first substrate (13) and the second substrate
(14) inside the catalytic converter (12). The external ring element
(20) may, in accordance with FIG. 3, be arranged on an outside
around the catalytic converter (12). In accordance with an
alternative embodiment may the external ring element (20) be
arranged such that it may be incorporated in a shell of the
catalytic converter (12) and in the shell surround the flow path
(2) which extends through the catalytic converter (12).
[0058] In accordance with the embodiment of FIG. 3 may the exhaust
gases enter into the catalytic converter (12) and flow through the
second substrate (14) for a first treatment. The exhaust gases have
after the first treatment through the second substrate (14) been
partly cleaned. The exhaust gases may after the second substrate
(14) enter into the space (19) arranged between the substrates (13,
14). The reductant may in the space (19) there be introduced and
mixed into and with the exhaust gases therein. The reductant may
e.g. be an ammonia gas. After the mixture between the exhaust gases
and the reductant, the mixture may continue into and through the
first substrate (13). The mixed exhaust gases will in the first
substrate (13) go through a chemical reaction. The reaction may
result in reduction of the NOx in the exhaust gases. After the
reduction of NOx, the exhaust gases may be lead or guided away from
the exhaust pipe system (3) through the outlet, or passage (24) of
the system.
[0059] FIG. 4 illustrates an alternative embodiment of the
embodiment of FIG. 3 in accordance with the invention. The supply
element (4) may in FIG. 4 extend across the flow path (2) by use of
an internal tube element (23). The tube element (23) may extend
through the flow path (2). The tube element (23) may comprise
discharge apertures (6a, 6b, 6c). The discharge apertures (6a, 6b,
6c) in accordance with FIG. 4 may comprise of small openings which
are arranged throughout the tube element (23) inside the flow path
(2). The tube element (23) may comprise of two parallel tubes being
arranged across the flow path (2). The respective tube being
parallel to each other of the tube element (23) comprises discharge
apertures (6a, 6b, 6c) throughout the respective tubes extension.
The tube element (23) may be arranged in the catalytic converter
(12), crossing the space (19) therein, and substantially extend
perpendicular to the flow path (2). Alternatively, the tube element
(23) may be arranged in and through the exhaust pipe (9) prior the
catalytic converter (12) in the flow path (2).
[0060] FIG. 5 illustrates an embodiment in accordance with the
invention where the supply element (4) may comprise a ring-shaped
part. The ring-shaped part may consist of the internal ring element
(22). The internal ring element (22) may in FIG. 5 be arranged
inside the flow path (2) and comprise discharge apertures (6a, 6b,
6c). The discharge apertures (6a, 6b, 6c) in accordance with FIG. 5
may be arranged on the ring element (22). The discharge apertures
(6a, 6b, 6c) in FIG. 5 may comprise of small openings being
arranged throughout the internal ring element (22). The supply
element (4) comprises a discharge conduit (21a) which connects with
the internal ring element (22). The discharge conduit (21a) may
extend through a wall element (11) and after the wall element (11)
lead into the flow path (2). The reductant may thereby be flown to
the discharge apertures (6a, 6b, 6c), which discharge apertures
(6a, 6b, 6c) may be arranged in the internal ring element (22) in
the flow path (2) and discharge and mix the reductant into the
exhaust gases flowing in the flow path (2).
[0061] FIG. 6 illustrates an embodiment in accordance with the
invention where the supply element (4) comprises a hose or flexible
tube which forms an alternative internal ring element (22) to that
in accordance with FIG. 5. The flexible tube comprises discharge
apertures (6a, 6b, 6c) which have a similar arrangement on the tube
to that in accordance to the embodiment of FIG. 5. The flexible
tube is connected to a discharge conduit (21a) which extends
through a wall element (11) and lead into the flow path (2). The
reductant may thereby be brought to flow to the discharge apertures
(6a, 6b, 6c) and into the flow path (2).
[0062] FIGS. 7a and 7b illustrates an embodiment in accordance with
the invention where the supply element (4) comprises a tube element
(23). The tube element (23) in accordance with FIGS. 7a and 7b
extends partly through the flow path (2). Further, the tube element
(23) extends through a center of the flow path (2). FIG. 7a is a
side view of the flow path (2). In FIG. 7a a number of discharge
apertures (6a, 6b, 6c), e.g. three, are connected with the tube
element (23) inside the flow path (2). However, if e.g. the flow
path would have a large diameter, whereby a larger volume of
exhaust gases would pass there through, then, in order to obtain an
efficient dispersion of reductant into the flow path, a greater
amount of discharge apertures may be required. The discharge
apertures (6a, 6b, 6c) are directed away from the tube element such
that the reductant will be symmetrically dispersed into the flow
path (2) from the discharge apertures (6a, 6b, 6c).
[0063] FIG. 7b is a view in the flow path (2). The view of FIG. 7b
is directed upstream in the flow path (2). The discharge apertures
(6a, 6b, 6c), in accordance with FIG. 7b, are arranged in the flow
path (2) along the tube element (23). The respective discharge
aperture (6a, 6b, 6c) comprises an outlet. The reductant is
dispersed, through the respective outlet, into the flow path (2).
The outlets of the respective discharge apertures (6a, 6b, 6c) are
arranged symmetrically in the flow path with respect to each other.
The outlets, in accordance with FIG. 7b, are arranged such that
they form a triangular pattern within the flow path.
[0064] FIG. 7c illustrates an alternative to the arrangements of
the discharge apertures (6a, 6b, 6c) of FIG. 7b. In FIG. 7c the
discharge apertures (6a, 6b, 6c) are arranged along the supply
element (4) such that the openings within the flow path (2) has a
diagonal extension across the flow path (2).
[0065] The embodiments in accordance with FIGS. 7a-7c have the
positive effects of improving mixing within the flow path (2)
through being arranged within the flow path (2). The arrangement
inside the flow path (2) causes turbulence of the exhaust gases and
the reductant upon passing the arrangement.
[0066] In accordance with the alternative embodiments of FIGS.
7a-7c, one of the three discharge apertures (6a, 6b, 6c) may be
directed opposite to the other. The discharge aperture directed
opposite to the other may thus, during use, receive the exhaust gas
into its opening. This has the consequence that a fraction of the
exhaust gas enters into the oppositely arranged discharge aperture
whereby pressure is built up therein. The exhaust gas, which has
entered into the discharge aperture, will mix with the reductant in
the supply element (4). After mixing in the supply element (4), the
exhaust gas and the reductant will exit through the two other
discharge apertures. This has the advantage of providing an ejector
effect for the reductant within the two discharge apertures. This
ejector effect may provide for a further improved mixing process or
effect as the reductant enters into the flow path (2) to mix with
the exhaust gases therein.
[0067] While there have been shown and described and pointed out
fundamental novel features of the invention as applied to a
preferred embodiment thereof, it will be understood that various
omissions and substitutions and changes in the form and details of
the devices illustrated, and in their operation, may be made by
those skilled in the art. For example, it is expressly intended
that all combinations of those elements and/or method steps which
perform substantially the same function in substantially the same
way to achieve the same results are within the scope of the
invention. Moreover, it should be recognized that structures and/or
elements and/or method steps shown and/or described in connection
with any disclosed form or embodiment of the invention may be
incorporated in any other disclosed or described or suggested form
or embodiment as a general matter of design choice. It is the
intention, therefore, to be limited only as indicated by the scope
of the claims appended hereto.
* * * * *