U.S. patent application number 14/436634 was filed with the patent office on 2015-09-03 for thermal storage device.
This patent application is currently assigned to KABUSHIKI KAISHA TOYOTA JIDOSHOKKI. The applicant listed for this patent is KABUSHIKI KAISHA TOYOTA CHUO KENKYUSHO, KABUSHIKI KAISHA TOYOTA JIDOSHOKKI. Invention is credited to Satoshi Hariu, Yasuki Hirota, Takashi Shimazu, Junya Suzuki, Gentaro Yamanaka, Takafumi Yamasaki, Takafumi Yamauchi.
Application Number | 20150247651 14/436634 |
Document ID | / |
Family ID | 50544466 |
Filed Date | 2015-09-03 |
United States Patent
Application |
20150247651 |
Kind Code |
A1 |
Hariu; Satoshi ; et
al. |
September 3, 2015 |
THERMAL STORAGE DEVICE
Abstract
A thermal storage device includes a reactor for generating heat
by chemically reacting with ammonia; an absorber, provided with an
absorbent, for storing ammonia absorbed by the absorbent; and a
connection line for connecting the reactor and absorber to each
other and moving ammonia between the reactor and absorber. The
reactor has a thermal storage member provided so as to cover an
outer peripheral portion of the catalyst, a porous sheet provided
so as to cover an outer peripheral portion of the thermal storage
member, and a casing for enclosing the thermal storage member and
porous sheet. One end of the connection line penetrates the casing
and opens to the porous sheet.
Inventors: |
Hariu; Satoshi; (Kariya-shi,
JP) ; Yamasaki; Takafumi; (Kariya-shi, JP) ;
Suzuki; Junya; (Kariya-shi, JP) ; Yamauchi;
Takafumi; (Nagakute-shi, JP) ; Hirota; Yasuki;
(Nagakute-shi, JP) ; Yamanaka; Gentaro;
(Nagakute-shi, JP) ; Shimazu; Takashi;
(Nagakute-shi, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
KABUSHIKI KAISHA TOYOTA JIDOSHOKKI
KABUSHIKI KAISHA TOYOTA CHUO KENKYUSHO |
Aichi
Aichi |
|
JP
JP |
|
|
Assignee: |
KABUSHIKI KAISHA TOYOTA
JIDOSHOKKI
Aichi
JP
KABUSHIKI KAISHA TOYOTA CHUO KENKYUSHO
Aichi
JP
|
Family ID: |
50544466 |
Appl. No.: |
14/436634 |
Filed: |
October 1, 2013 |
PCT Filed: |
October 1, 2013 |
PCT NO: |
PCT/JP2013/076726 |
371 Date: |
April 17, 2015 |
Current U.S.
Class: |
60/300 ;
126/263.01 |
Current CPC
Class: |
F01N 13/009 20140601;
Y02T 10/24 20130101; F01N 2610/02 20130101; F01N 3/035 20130101;
F01N 2240/10 20130101; F01N 3/2006 20130101; F01N 3/0814 20130101;
F01N 3/2066 20130101; F28D 20/02 20130101; Y02A 50/20 20180101;
F24V 30/00 20180501; F28D 20/00 20130101; Y02A 50/2325 20180101;
Y02T 10/12 20130101; F01N 3/0828 20130101; Y02T 10/26 20130101;
F01N 3/106 20130101; F01N 3/2864 20130101 |
International
Class: |
F24J 1/00 20060101
F24J001/00; F01N 3/20 20060101 F01N003/20 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 26, 2012 |
JP |
2012-236943 |
Claims
1. A thermal storage device for warming up a catalyst arranged in
an exhaust system of an internal combustion engine of a vehicle,
the thermal storage device comprising: a reactor for generating
heat by chemically reacting with ammonia; an absorber, provided
with an absorbent, for storing ammonia absorbed by the absorbent;
and a connection line for connecting the reactor and absorber to
each other and moving ammonia between the reactor and absorber;
wherein the reactor has a thermal storage member provided so as to
cover an outer peripheral portion of the catalyst, a porous sheet
provided so as to cover an outer peripheral portion of the thermal
storage member, and a casing for enclosing the thermal storage
member and porous sheet; and wherein one end of the connection line
penetrates the casing and opens to the porous sheet.
2. The thermal storage device according to claim 1, wherein the
reactor further has a heat-insulating member enclosed in the casing
and provided so as to cover an outer peripheral portion of the
porous sheet.
3. The thermal storage device according to claim 2, wherein the
porous sheet is formed from stainless steel or ceramic.
4. The thermal storage device according to claim 1, wherein the
porous sheet is formed from stainless steel or ceramic.
Description
TECHNICAL FIELD
[0001] The present invention relates to a thermal storage device
for warming up a catalyst provided in an exhaust system of an
internal combustion engine of a vehicle.
BACKGROUND ART
[0002] A vehicle has an exhaust system provided with a catalyst and
the like in order to purify environmental pollutants (HC, CO, NOx,
and the like) contained in an exhaust gas discharged from its
engine. The catalyst has an optimal temperature (active
temperature) for activating its purification performance. At the
time of starting the engine, the exhaust gas has a low temperature,
which takes time to reach the active temperature of the catalyst.
In order for the temperature in the catalyst to rise to the active
temperature in a short time when the temperature of the exhaust gas
is low at the time of starting the engine and the like, a device
for warming up the catalyst is necessary. As such a device, thermal
storage devices utilizing the reaction heat of chemical reactions
have been known. The thermal storage devices cut down fuel
consumption losses and then perform warm-up. Patent Literature 1
discloses a catalyst warm-up device in which a thermal storage
member is arranged on the outside of a catalyst, while the reaction
heat of a chemical reaction of the thermal storage device is
utilized for warming up the catalyst.
CITATION LIST
Patent Literature
[0003] Patent Literature 1: Japanese Patent Application Laid-Open
No. S59-208118
SUMMARY OF INVENTION
Technical Problem
[0004] The catalyst is supported by a honeycomb base disposed
within an exhaust pipe and required to be protected against shocks
at the time when the vehicle is running. Therefore, when the
thermal storage member is arranged on the outside of the catalyst
as in Patent Literature 1, a mat or the like is provided between
the catalyst and thermal storage member in general and absorbs the
shocks. When such a mat is provided between the catalyst and
thermal storage member, however, heat generated in the thermal
storage member is transmitted to the catalyst through the mat,
which lowers the efficiency of heat transfer to the catalyst. When
the mat or the like is not provided between the catalyst and
thermal storage member, the heat transfer efficiency does not
lower, but shocks occurring when the vehicle is running are hard to
absorb.
[0005] It is therefore an object of the present invention to
provide a thermal storage device which can prevent the thermal
transfer efficiency from lowering and absorb shocks at the time
when the vehicle is running.
Solution to Problem
[0006] The present invention provides a thermal storage device for
warming up a catalyst arranged in an exhaust system of an internal
combustion engine of a vehicle, the thermal storage device
including a reactor for generating heat by chemically reacting with
ammonia; an absorber, provided with an absorbent, for storing
ammonia absorbed by the absorbent; and a connection line for
connecting the reactor and absorber to each other and moving
ammonia between the reactor and absorber; the reactor having a
thermal storage member provided so as to cover an outer peripheral
portion of the catalyst, a porous sheet provided so as to cover an
outer peripheral portion of the thermal storage member, and a
casing for enclosing the thermal storage member and porous sheet;
one end of the connection line penetrating the casing and opening
to the porous sheet.
[0007] An exhaust system of an internal combustion engine of a
vehicle is provided with a catalyst for purifying an exhaust gas
and provided with a thermal storage device for warming up the
catalyst. The present invention includes a reactor for generating
heat by chemically reacting with ammonia and an absorber for
storing ammonia absorbed by an absorbent. The reactor and absorber
are connected to each other through a connection line in order to
move ammonia between the reactor and absorber. The reactor has a
thermal storage member and a porous sheet, which are enclosed in a
casing. The thermal storage member is provided so as to cover an
outer peripheral portion of the catalyst and warms up the catalyst.
The porous sheet is provided so as to cover an outer peripheral
portion of the thermal storage member and constitutes passages for
ammonia. One end of the connection line opens to the porous sheet,
so that ammonia flows into the latter from the connection line.
Ammonia having flown therein is uniformly dispersed by the porous
sheet, so as to be supplied to the thermal storage member. The
porous sheet produces a stress buffer effect. Therefore, when the
thermal storage member volume is increased by ammonia supplied
thereto, the porous sheet inhibits the thermal storage member from
deforming radially of the exhaust pipe. Inhibiting the thermal
storage member from deforming radially of the exhaust pipe
restrains the heat transfer distance from becoming longer. The
porous sheet also absorbs shocks at the time when the vehicle is
running and the like. As a result of these, the heat transfer
efficiency of the heat generated in the thermal storage member to
the catalyst can be prevented from lowering, while the shocks at
the time when the vehicle is running and the like can be
absorbed.
[0008] The reactor may further have a heat-insulating member
enclosed in the casing and provided so as to cover an outer
peripheral portion of the porous sheet.
[0009] In the reactor, the thermal storage member, porous sheet,
and heat-insulating member are enclosed in the casing. The
heat-insulating member is provided so as to cover an outer
peripheral portion of the porous sheet and prevents heat from
escaping to the outside. Therefore, the heat-insulating member
absorbs shocks at the time when the vehicle is running and the
like, while inhibiting the thermal storage member from deforming
radially of the exhaust pipe when the thermal storage member volume
is increased by ammonia supplied thereto. As a result of these, the
heat transfer efficiency of the heat generated in the thermal
storage member to the catalyst can further be prevented from
lowering, while the shocks at the time when the vehicle is running
and the like can be absorbed more.
[0010] The porous sheet may be formed from stainless steel or
ceramic. In this case, the porous sheet serving as passages for
ammonia is not corroded by ammonia, which enables the porous sheet
to produce a stress buffer effect.
Advantageous Effects of Invention
[0011] The present invention can provide a thermal storage device
which can prevent the thermal transfer efficiency from lowering and
absorb shocks at the time when the vehicle is running.
BRIEF DESCRIPTION OF DRAWINGS
[0012] FIG. 1 is a schematic structural diagram of an exhaust
purification system provided with the thermal storage device in
accordance with an embodiment of the present invention; and
[0013] FIG. 2 is a sectional view of a reactor of the thermal
storage device in accordance with the embodiment.
DESCRIPTION OF EMBODIMENTS
[0014] In the following, an embodiment of a thermal storage device
in accordance with the present invention will be explained in
detail with reference to the drawings. In the drawings, the same or
equivalent constituents will be referred to with the same signs
while omitting their overlapping descriptions.
[0015] In this embodiment, the thermal storage device in accordance
with the present invention is employed in a thermal storage device
implemented in an exhaust purification system provided in an
exhaust system of an engine (internal combustion engine) of a
vehicle. The exhaust purification system in accordance with this
embodiment includes DOC (Diesel Oxidation Catalyst), SCR (Selective
Catalytic Reduction), and ASC (Ammonia Slip Catalyst) as catalysts,
DPF (Diesel Particulate Filter) as a filter, and a chemical thermal
storage device for warming up the catalysts.
[0016] With reference to FIGS. 1 and 2, an exhaust purification
system 1 in accordance with this embodiment will be explained. FIG.
1 is a schematic structural diagram of the exhaust purification
system provided with the thermal storage device in accordance with
this embodiment. FIG. 2 is a sectional view of the reactor of the
thermal storage device in accordance with this embodiment.
[0017] The exhaust purification system 1 has a diesel oxidation
catalyst (DOC) 4, a diesel particulate filter (DPF) 5, a selective
catalytic reduction (SCR), and an ammonia slip catalyst (ASC) 7.
The DOC 4, DPF 5, SCR 6, and ASC 7 are arranged in an order of the
DOC 4, the DPF 5, the SCR 6, and the ASC 7 from the upstream side
to downstream side of an exhaust pipe 3 connected to the exhaust
side of an engine 2.
[0018] The DOC 4 oxidizes HC, CO, and the like contained in the
exhaust gas. The DPF 5 collects and removes PM (Particulate Matter)
contained in the exhaust gas. The SCR 6 supplies ammonia (NH.sub.3)
or urea water to the upstream side within the exhaust pipe 3 from
an injector 6a, so that NOx contained in the exhaust gas and
ammonia chemically react with each other, thereby reducing and
purifying NOx. Urea water is hydrolyzed into ammonia. The ASC 7
oxidizes ammonia having flowed through the SCR 6 to the downstream
side thereof.
[0019] The catalysts 4, 6, 7 have respective temperature regions
where they can exhibit purification performances for environmental
pollutants (i.e., active temperatures). For example, the lower
limit for active temperature of the DOC 4 is about 150.degree. C.
Immediately after starting the engine 2 and the like, the
temperature of the exhaust gas just after being discharged from the
engine 2 is relatively low, i.e., about 100.degree. C. In order for
the catalysts 4, 6, 7 to exhibit their purification performances
even immediately after starting the engine 2 and the like, it is
necessary for the temperatures in the catalysts 4, 6, 7 to rise
promptly to their active temperatures. Therefore, the exhaust
purification system 1 has a thermal storage device 8 for warming up
the catalysts. The exhaust purification system 1 is provided with a
temperature sensor for detecting the temperature of the exhaust gas
discharged from the engine 2 (or temperatures of the
catalysts).
[0020] The thermal storage device 8 is a chemical thermal storage
device which warms up the catalysts without necessitating external
energy such as electric power. The thermal storage device 8 usually
stores the heat of the exhaust gas (exhaust heat) and, when
necessary, uses the stored heat, so as to warm up the catalysts.
The thermal storage device 8 warms up the DOC 4, which is a
catalyst located on the upstream side in the exhaust pipe 3. The
thermal storage device 8 includes a reactor 9, an absorber 10, a
connection line 11, and an open-close valve 12.
[0021] The reactor 9 is provided all over the surface of an outer
peripheral portion of the DOC 4. The reactor 9 has a thermal
storage member (reactive member) which chemically reacts with
ammonia. In the reactor 9, ammonia and the thermal storage member
react with each other, thereby generating heat. Examples of the
thermal storage member include metal chlorides, metal bromides, and
metal iodides, specific examples of which include MgCl.sub.2,
CaCl.sub.2, NiCl.sub.2, ZnCl.sub.2, and SrCl.sub.2. The structure
of the reactor 9 will be explained later in detail.
[0022] The absorber 10 incorporates therein activated carbon as an
absorbent which physically absorbs ammonia. The absorber 10 stores
ammonia by causing the activated carbon to physically absorb
ammonia and releases ammonia by separating it from the activated
carbon.
[0023] The connection line 11 connects the reactor 9 and absorber
10 to each other. The connection line 11 is a conduit for moving
ammonia between the reactor 9 and absorber 10. The open-close valve
12 is arranged in the connection line 11. When the open-close valve
12 is opened, ammonia can move between the reactor 9 and absorber
10 through the connection line 11. The open-close valve 12 is
opened and closed under the control of an ECU (Electronic Control
Unit) (not depicted), which controls the engine 2, or the like.
[0024] With reference to FIG. 2, the structure of the reactor 9
will be explained. As mentioned above, the reactor 9 is provided so
as to cover the whole surface of the outer peripheral portion of
the DOC 4 through the exhaust pipe 3. That is, the reactor 9 is
arranged so as to cover the outer peripheral portion of the DOC 4
as a whole indirectly through the exhaust pipe 3. The DOC 4 has a
honeycomb base. The honeycomb base is arranged in the thin exhaust
pipe 3 having an annular cross section. The honeycomb base supports
the catalyst. The reactor 9 has a plurality of thermal storage
members 9a, a porous sheet 9b, a heat-insulating member 9c, and a
casing 9d. The plurality of thermal storage members 9a, porous
sheet 9b, heat-insulating member 9c, and casing 9d are arranged on
the outside of the DOC 4.
[0025] A pair of annular plates (not depicted) are provided
orthogonal to the outer periphery of the exhaust pipe 3 on the
outer periphery of the exhaust pipe in a portion where the DOC 4 is
located. One annular plate is arranged about a position where the
upstream end of the DOC 4 is located. The other annular plate is
arranged about a position where the downstream end of the DOC 4 is
located. The exhaust pipe 3 and the pair of annular plates define a
space for containing the thermal storage members 9a, porous sheet
9b, and heat-insulating member 9c.
[0026] Each thermal storage member 9a is in a solid tablet form.
When arranged on the outside of the exhaust pipe 3, as illustrated
in FIG. 2, the plurality of thermal storage members 9a as a whole
exhibit a substantially annular ring form in a cross section taken
along a plane orthogonal to the outer periphery of the exhaust pipe
3. The plurality of thermal storage members 9a are arranged in a
region between the pair of annular plates in the outer periphery of
the exhaust pipe 3 so as to align longitudinally and
circumferentially of the exhaust pipe 3. The plurality of thermal
storage members 9a are in contact with the outer periphery of the
exhaust pipe 3. Therefore, the plurality of thermal storage members
9a arranged in contact with the outer periphery of the exhaust pipe
3 warm up the DOC 4 through the exhaust pipe 3. Since the exhaust
pipe 3 is thin, the plurality of thermal storage members 9a warm up
the DOC 4 substantially directly. The plurality of thermal storage
members 9a are arranged so as to cover the outer periphery of the
exhaust pipe 3 directly. That is, the plurality of thermal storage
members 9a are arranged so as to cover the outer peripheral portion
of the DOC 4 as a whole indirectly through the exhaust pipe 3.
[0027] The volume of thermal storage members 9a increases when
ammonia infiltrates therein. The plurality of thermal storage
members 9a are arranged with gaps between the thermal storage
members 9a adjacent to each other longitudinally of the exhaust
pipe 3 so that the volume of thermal storage members 9a do not
increase radially but longitudinally of the exhaust pipe 3. That
is, when containing no ammonia, the thermal storage members 9a in
contact with each other, whose number is the same as those
longitudinally arranged between a pair of annular plates, have a
total length shorter than the distance between the pair of annular
plates.
[0028] The porous sheet 9b is in the form of a thin sheet. When
arranged on the outside of the exhaust pipe 3, the porous sheet 9b
has a substantially cylindrical form. Therefore, the porous sheet
9b as a whole exhibits a substantially annular ring form in a cross
section taken along a plane orthogonal to the outer periphery of
the exhaust pipe 3 as illustrated in FIG. 2. The porous sheet 9b is
arranged between the pair of annular plates so as to extend along
the outer peripheries of the plurality of thermal storage members
9a placed along the outer periphery of the exhaust pipe 3. The
porous sheet 9b is in the form of a fine filter (net) and
constitutes passages for ammonia. For constituting the passages for
ammonia, it is necessary for the porous sheet 9b to be formed from
a material which is not corroded by ammonia. For producing a stress
buffer effect, it is also necessary for the porous sheet 9b to be
formed from an elastically deformable material (flexible material).
Examples of materials satisfying these conditions include stainless
steel and ceramics. The porous sheet 9b is arranged so as to
directly cover the outer peripheral portions of the plurality of
thermal storage members 9a exhibiting a substantially cylindrical
form as a whole.
[0029] The heat-insulating member 9c has a predetermined thickness.
When arranged on the outside of the exhaust pipe 3, the
heat-insulating member 9c has a substantially cylindrical form.
Therefore, the heat-insulating member 9c exhibits a substantially
annular ring form in a cross section taken along a plane orthogonal
to the outer periphery of the exhaust pipe 3 as illustrated in FIG.
2. The heat-insulating member 9c is arranged between the pair of
annular plates so as to extend along the outer periphery of the
porous sheet 9b. The heat-insulating member 9c is relatively hard
in order to inhibit the volume of thermal storage members 9a from
increasing radially of the exhaust pipe 3. For producing a stress
buffer effect, it is also necessary for the heat-insulating member
9c to be formed from an elastically deformable material. The
heat-insulating member 9c is also porous in this embodiment. It is
not necessary for the heat-insulating member 9c to be porous. The
heat-insulating member 9c is arranged so as to directly cover the
outer peripheral portion of the porous sheet 9b.
[0030] The casing 9d is arranged between the pair of annular plates
so as to extend along the outer periphery of the heat-insulating
member 9c. The casing 9d has both end portions welded to the pair
of annular plates, respectively. Therefore, the space defined by
the casing 9d, exhaust pipe 3, and pair of annular plates is closed
and encloses therein the thermal storage members 9a, porous sheet
9b, and heat-insulating member 9c. The thermal storage members 9a
are enclosed in the closed space and thus can repeatedly chemically
react with ammonia. The outer periphery of the casing 9d is
provided with a flange 13 for attaching the exhaust pipe and the
like to a vehicle body.
[0031] The connection line 11 has one end 11 a which penetrates the
casing 9d and heat-insulating material 9c and opens to the outer
periphery side of the porous sheet 9b. Therefore, when ammonia is
released from the absorber 10 while the open-close valve 12 is
open, ammonia flows into the porous sheet 9b from the one end 11a
of the connection line 11.
[0032] Actions of the thermal storage device 8 (the reactor 9 in
particular) in the exhaust purification system 1 will now be
explained. When the vehicle is stopped (the engine 2 is stopped),
the open-close valve 12 is closed. Therefore, even when separated
from activated carbon in the absorber 10, ammonia is not supplied
to the reactor 9 through the connection line 11.
[0033] When the temperature of the exhaust gas discharged from the
engine 2 is lower than a predetermined temperature (a temperature
lower than the active temperature of the DOC 4 and the like) after
starting the engine 2, the open-close valve 12 is opened under the
control of the ECU immediately after starting the engine 2, for
example, whereby ammonia is supplied to the reactor 9 through the
connection line 11. At this time, the pressure of the absorber 10
is higher than that of the reactor 9, so that ammonia moves toward
the reactor 9.
[0034] In the reactor 9, ammonia flows into the porous sheet 9b
from one end 11a of the connection line 11. The porous sheet 9b
diffuses ammonia uniformly. The uniformly diffused ammonia is
supplied equally to the plurality of thermal storage members 9a
disposed on the outer periphery of the exhaust pipe 3. Each thermal
storage member 9a (made of MgCl.sub.2, for example) chemically
reacts with the supplied ammonia, so as to occlude ammonia, thereby
generating heat. When each thermal storage member 9a is made of
MgCl.sub.2, MgCl.sub.2 and ammonia form a coordinate bond. That is,
a reaction from the left side to right side in the following
reaction formula occurs. The heat generated from each thermal
storage member 9a is transmitted to the DOC 4 through the thin
exhaust pipe 3. As a result, the temperature of each of the
catalysts such as the DOC 4 rises to the active temperature
suitable for purifying the environmental pollutants in the exhaust
gas.
MgCl.sub.2+6NH.sub.3MgCl.sub.2.6.NH.sub.3+.DELTA.H
.DELTA.H=67 kJ/mol (NH.sub.3)
[0035] In the reactor 9, the heat-insulating member 9c makes it
hard for heat to escape to the outside, whereby the heat generated
in each thermal storage member 9a is transmitted to the inside (the
DOC 4 side). In the reactor 9, the volume of each thermal storage
member 9a is increased by ammonia supplied thereto. At this time,
each thermal storage member 9a is inhibited from deforming radially
of the exhaust pipe 3 by the hard heat-insulating member 9c (and
further by the stress buffer effect produced by the porous sheet 9b
and heat-insulating member 9c), so as to deform longitudinally of
the exhaust pipe 3. This restrains the heat transfer distance from
each thermal storage member 9a from becoming longer. In the reactor
9, each thermal storage member 9a is arranged on the outer
periphery of the thin exhaust pipe 3, thereby substantially
directly warming up the DOC 4 (catalyst). As a result of these, the
efficiency of heat transfer from each thermal storage member 9a to
the DOC 4 (catalyst) can be prevented from lowering.
[0036] When the temperature of the exhaust gas discharged from the
engine 2 is higher than a predetermined temperature (a temperature
higher than the active temperature of the DOC 4 and the like), the
exhaust heat of the exhaust gas is imparted to the thermal storage
members 9a in the reactor 9. This separates ammonia from the
thermal storage members 9a, thereby yielding high-temperature
ammonia. That is, a reaction from the right side to left side in
the above-mentioned reaction formula occurs. The separated ammonia
returns from the reactor 9 to the absorber 10 through the
connection line 11. That is, the separated ammonia passes through
the porous sheet 9b from the thermal storage members 9a and then
returns to the absorber 10 through the connection line 11. At this
time, the pressure of the reactor 9 is higher than that of the
absorber 10, so that ammonia moves toward the absorber 10. In the
absorber 10, the activated carbon physically absorbs and stores
ammonia.
[0037] When a vehicle is running, shocks caused by the running
vehicle are absorbed by the stress buffer effect produced by the
porous sheet 9b and heat-insulating member 9c. Therefore, the DOC 4
and thermal storage members 9a can be protected against the shocks
caused by the running vehicle. In particular, when vehicles
collide, large shocks caused by the collision are absorbed by the
stress buffer effect produced by the porous sheet 9b and
heat-insulating member 9c, whereby the DOC 4 and the like can be
prevented from being damaged.
[0038] In the thermal storage device 8 (the reactor 9 in
particular) of the exhaust purification system 1, the thermal
storage members 9a are disposed on the outer peripheral portion of
the DOC 4 (the outer periphery of the thin exhaust pipe 3), while
the porous sheet 9b is provided all over the outer periphery of the
thermal storage members 9a. This can prevent the heat transfer
efficiency of the heat generated in the thermal storage members 9a
to the DOC 4 (catalyst) from lowering and absorb shocks at the time
when the vehicle is running and the like. As a result, the
efficiency of heating by the thermal storage device 8 does not
lower, so that heat loss can be suppressed, whereby the temperature
of the DOC 4 and the like rapidly reaches the active
temperature.
[0039] In the thermal storage device 8, the heat-insulating member
9c is provided all over the outer periphery of the porous sheet 9b.
This can further prevent the heat transfer efficiency of the heat
generated in the thermal storage members 9a to the DOC 4 from
lowering and absorb shocks more at the time when the vehicle is
running and the like. In particular, since the heat-insulating
member 9c is hard, the volume of thermal storage members 9a
increased by ammonia supplied thereto can be inhibited from
deforming radially of the exhaust pipe 3, whereby the heat transfer
distance can be prevented from becoming longer.
[0040] In the thermal storage device 8, the porous sheet 9b is
formed from stainless steel or ceramic. Therefore, the porous sheet
9b serving as passages for ammonia is not corroded by ammonia,
which enables the porous sheet 9b to produce a stress buffer
effect.
[0041] While an embodiment in accordance with the present invention
is explained in the foregoing, the present invention can be carried
out in various modes without being restricted to the
above-mentioned embodiment.
[0042] For example, while the present invention is employed in an
exhaust purification system including the DOC, SCR, and ASC as
catalysts and further the DPF as a filter in this embodiment, its
applicable exhaust purification systems are not limited thereto.
The present invention is also employable in other exhaust
purification systems having various structures as long as they
include at least a catalyst and a thermal storage device for
warming up the catalyst. The engine is not limited to diesel
engines, but may be any of gasoline engines and the like.
[0043] While the DOC 4 is a catalyst to warm up and is arranged
with the reactor 9 of the thermal storage device 8 in this
embodiment, the reactor 9 may be placed at other locations
according to catalysts to warm up. When the catalyst to warm up is
the SCR 6, for example, the SCR 6 may be arranged with the reactor
9. In this case, the reactor 9 is provided so as to cover an outer
peripheral portion of the SCR 6.
[0044] The material for the porous sheet 9b is stainless steel or
ceramic in this embodiment but is not limited thereto. The porous
sheet 9b may also be made of any of materials other than stainless
steel and ceramics as long as they are elastically deformable
without being corroded by ammonia.
[0045] While the thermal storage device 8 is provided with the
heat-insulating member 9c in this embodiment, it is not necessary
for the thermal storage device 8 to be provided with the
heat-insulating member 9c as in this embodiment. When not provided
with the heat-insulating member 9c, the thermal storage device 8
may include porous sheets arranged in two layers on inner and outer
sides. In this case, the inner and outer porous sheets may be soft
and hard in order to produce a stress buffer effect and a
deformation suppression effect, respectively.
[0046] The reactor 9 (the thermal storage members 9a, porous sheet
9b, and heat-insulating member 9c) is arranged so as to cover the
outer peripheral portion of the catalyst (DOC 4) as a whole in this
embodiment, but is not restricted thereto. The reactor 9 may also
be arranged so as to cover a portion of the outer peripheral
portion of the catalyst.
INDUSTRIAL APPLICABILITY
[0047] The present invention can be utilized in a thermal storage
device for warming up catalysts provided in exhaust systems of
internal combustion engines (e.g., diesel engines).
REFERENCE SIGNS LIST
[0048] 1: exhaust purification system; 2: engine; 3: exhaust pipe;
4: diesel oxidation catalyst (DOC); 5: diesel particulate filter
(DPF); 6: selective catalytic reduction (SCR); 6a: injector; 7:
ammonia slip catalyst (ASC); 8: thermal storage device; 9: reactor;
9a: thermal storage member; 9b: porous sheet; 9c: heat-insulating
member; 9d: casing; 10: absorber; 11: connection line; 12:
open-close valve; 13: flange.
* * * * *