U.S. patent application number 11/814984 was filed with the patent office on 2009-01-15 for muffler for small engine.
This patent application is currently assigned to HIRAOKA MANUFACTURING CO.,LTD. Invention is credited to Hidenori Mukaida.
Application Number | 20090013673 11/814984 |
Document ID | / |
Family ID | 36740465 |
Filed Date | 2009-01-15 |
United States Patent
Application |
20090013673 |
Kind Code |
A1 |
Mukaida; Hidenori |
January 15, 2009 |
MUFFLER FOR SMALL ENGINE
Abstract
A muffler for a small engine includes a first expansion chamber
12 for exhaust gas having an exhaust gas inlet 11 being connected
to an exhaust gas outlet of the engine, a second expansion chamber
15 being partitioned from the first expansion chamber 12 by a
partition plate 14 and being communicated with the first expansion
chamber 12 through a first communicating hole 13 on the partition
plate 14, and a third expansion chamber 18 being partitioned from
the second expansion chamber 15 by the partition plate 14 and being
communicated with the second expansion chamber 15 through a second
communicating hole 16 on the partition plate 14 and having an
exhaust gas outlet 17. A first heat resistant mesh catalyst 19 is
disposed on the exhaust gas inlet 11. A first exhaust gas purifier
20 composed of a heat resistant knit fabric 20a coated with a
catalyst for purifying the exhaust gas is disposed on the
communicating hole 13 on the partition plate 14. Accordingly, the
muffler for a small engine having a large muffling effect and a
large purification effect on the exhaust gas can be provided. A
manufacturing process of the exhaust gas purifier is simple and
thereby a manufacturing cost of the muffler for a small engine is
reduced.
Inventors: |
Mukaida; Hidenori; (Tokyo,
JP) |
Correspondence
Address: |
MERCHANT & GOULD PC
P.O. BOX 2903
MINNEAPOLIS
MN
55402-0903
US
|
Assignee: |
HIRAOKA MANUFACTURING
CO.,LTD
|
Family ID: |
36740465 |
Appl. No.: |
11/814984 |
Filed: |
January 27, 2006 |
PCT Filed: |
January 27, 2006 |
PCT NO: |
PCT/JP2006/301325 |
371 Date: |
May 30, 2008 |
Current U.S.
Class: |
60/299 ;
181/227 |
Current CPC
Class: |
F01N 1/089 20130101;
F01N 3/05 20130101; F01N 3/2885 20130101; F01N 13/141 20130101;
Y02T 10/20 20130101; F01N 2590/06 20130101; F01N 13/14 20130101;
F01N 2240/36 20130101; F01N 2330/12 20130101; F01N 2450/30
20130101; Y02T 10/12 20130101; F01N 13/002 20130101; F01N 2470/30
20130101; F01N 1/165 20130101 |
Class at
Publication: |
60/299 ;
181/227 |
International
Class: |
F01N 3/28 20060101
F01N003/28; F01N 7/08 20060101 F01N007/08 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 28, 2005 |
JP |
2005-020864 |
Claims
1. A muffler for a small engine, comprising: a first expansion
chamber of exhaust gas having an exhaust gas inlet being connected
to an exhaust gas outlet of the engine; a second expansion chamber
of the exhaust gas being partitioned from the first expansion
chamber by a partition plate and being communicated with the first
expansion chamber through a first communicating hole through the
partition plate; a third expansion chamber of the exhaust gas
having an exhaust gas outlet and being partitioned from the second
expansion chamber by the partition plate and being communicated
with the second expansion chamber through a second communicating
hole through the partition plate, a first heat resistant mesh
catalyst disposed at the exhaust gas inlet; and a first exhaust gas
purifier composed of a knit fabric coated with a catalyst for
purifying the exhaust gas and disposed at the first communicating
hole.
2. The muffler for a small engine according to claim 1, further
comprising: a heat resistant cover having at least one exhaust gas
inlet for supporting the knit fabric.
3. The muffler for a small engine according to claim 1, further
comprising: a second heat resistant mesh catalyst and a heat
resistant cover having a plurality of exhaust gas outlets disposed
on an outlet side of the exhaust gas; and a third heat resistant
mesh catalyst disposed replaceably on the exhaust gas outlet
wherein the first exhaust gas purifier is disposed on an exhaust
gas inlet side of the first communicating hole through the
partition plate.
4. The muffler for a small engine according to claim 1, further
comprising: a heat resistant cover made of a heat resistant mesh
for supporting the knit fabric.
5. The muffler for a small engine according to claim 1, wherein at
least an outer wall of the second expansion chamber which is not
disposed on a side where the muffler is attached is constituted by
a double-wall structure of walls.
6. The muffler for a small engine according to claim 1, wherein the
outer wall of the second expansion chamber which is not at least
the wall of the engine side is constituted by the double-wall
structure of walls and a heat insulator is packed into a space
between the double walls.
7. The muffler for a small engine according to claim 1, further
comprising: an exhaust gas receiver disposed inside the first
expansion chamber disposed opposite the exhaust gas inlet, being
connected to the exhaust gas inlet and having an exhaust gas outlet
opposite the exhaust gas inlet; and a second exhaust gas purifier
composed of the heat resistant knit fabric coated with the catalyst
for purifying the exhaust gas, being installed in a vicinity of the
exhaust gas outlet inside the exhaust gas receiver; and an inclined
surface formed on the exhaust gas outlet so as to flow the exhaust
gas in a direction toward the first exhaust gas purifier.
8. The muffler for a small engine according to claim 1, wherein the
first heat resistant mesh catalyst is made of a SUS310S stainless
steel mesh coated with the catalyst.
9. The muffler for a small engine according to claim 3, wherein the
second heat resistant mesh catalyst is made of the SUS310S
stainless steel mesh coated with the catalyst for purifying the
exhaust gas, the heat resistant cover is made of a SUS310S
stainless steel sheet, and the third heat resistant mesh catalyst
is made of the SUS310S stainless steel mesh coated with the
catalyst for purifying the exhaust gas.
10. The muffler for a small engine according to claim 7, wherein
the exhaust gas receiver is made of the SUS310S stainless steel
sheet.
11. A muffler for a small engine, comprising: a first expansion
chamber of the exhaust gas having an exhaust gas inlet being
connected to an exhaust gas outlet of the engine; a second
expansion chamber being partitioned from the first expansion
chamber by a partition plate; a third expansion chamber having an
exhaust gas outlet being communicated with the second expansion
chamber through a second communicating hole on the partition plate,
a first heat resistant mesh catalyst disposed at the exhaust gas
inlet; a convex part having at least one first communicating hole
and protruding toward the first expansion chamber, the convex part
made in an integrally molding manner with the partition plate; a
first exhaust gas purifier composed of a heat resistant knit fabric
coated with the catalyst for purifying the exhaust gas installed on
a concave part on the side of the second expansion chamber of the
convex part; and a heat resistant cover having an exhaust gas
outlet disposed for covering the first exhaust gas purifier in a
direction from the second expansion chamber.
12. A muffler for a small engine, comprising: a first expansion
chamber of the exhaust gas having an exhaust gas inlet being
connected to an exhaust gas outlet of the engine; a second
expansion chamber which is partitioned from the first expansion
chamber by a partition plate; a third expansion chamber having an
exhaust gas outlet being communicated with the second expansion
chamber through a second communicating hole on the partition plate;
a first heat resistant mesh catalyst disposed on the exhaust gas
inlet; a convex part having an exhaust gas outlet and protruding
toward the second expansion chamber, the convex part made in an
integrally molding manner with the partition plate; a heat
resistant knit fabric coated with a catalyst for purifying the
exhaust gas installed on an exhaust gas inlet side on the side of
the first expansion chamber of the convex part; and a heat
resistant cover having an exhaust gas outlet disposed for covering
the first exhaust gas purifier the first expansion chamber.
13. A muffler for a small engine, comprising: a first expansion
chamber for the exhaust gas having an exhaust gas inlet being
connected to an exhaust gas outlet of the engine; a second
expansion chamber being partitioned from the first expansion
chamber by a partition plate having a communicating hole; a first
heat resistant mesh catalyst disposed on the exhaust gas inlet; a
first exhaust gas purifier composed of a heat resistant knit fabric
coated with a catalyst for purifying the exhaust gas is disposed on
the first communicating hole on the partition plate; and an outside
air suction pipe disposed through the second expansion chamber, a
portion of the outside air suction pipe disposed opposite the first
exhaust gas purifier and composed of a double pipe, an end of the
outside air suction pipe bored through the outer wall and
communicating with an outside air, wherein a plurality of suction
holes are bored through an outer pipe of the double pipe and the
other end of the outside air suction pipe communicates with an
exhaust gas outlet through an exhaust gas guide.
14. The muffler for a small engine according to claim 13, wherein
the exhaust gas pipe is provided with a pipe having a check valve
and being communicated with the first expansion chamber of the
exhaust gas.
15. A muffler for a small engine, comprising: a first expansion
chamber of exhaust gas having an exhaust gas inlet being connected
to an exhaust gas outlet of the engine; a second expansion chamber
partitioned from the first expansion chamber by a partition plate
having a communicating hole; a first heat resistant mesh catalyst
disposed on the exhaust gas inlet; a first exhaust gas purifier
composed of a heat resistant knit fabric coated with a catalyst for
purifying the exhaust gas disposed on a first communicating hole on
the partition plate; and an exhaust gas pipe communicating the
second expansion chamber with an exhaust gas outlet provided with a
pipe being communicated with the first expansion chamber of the
exhaust gas and having a check valve.
16. The muffler for a small engine according to claim 1, wherein a
concave groove which is communicated with the third expansion
chamber at an end and with the outside air at the other end is
formed on an outer surface of the muffler, and a groove cover
covers the concave groove.
17. The muffler for a small engine according to claim 1, wherein an
outside air suction pipe being opened at each end is fixed along
the outer wall of the muffler so as to communicate with the exhaust
gas outlet at an end and with the outside air at the other end.
Description
TECHNICAL FIELD
[0001] The present invention relates to a muffler for a small
engine suited for use in a brush cutter or a chain saw, for
example.
BACKGROUND ART
[0002] A conventional muffler for a small engine comprises, as
shown in FIG. 21, an exhaust gas first expansion chamber 2 having
an exhaust gas inlet 1 connected to an exhaust gas outlet of the
engine, and an exhaust gas second expansion chamber 4 having an
exhaust gas outlet 3. Between the first expansion chamber 2 and the
second expansion chamber 4, for example, an exhaust gas purifier 5
made of a honeycomb-like stainless steel support body having
innumerable small holes along an axial direction and coated with a
catalyst such as Rhodium, Palladium, etc., is disposed.
[0003] Further, a conventional muffler for a small engine
comprises, as shown in FIG. 22, an exhaust gas first expansion
chamber 2 having an exhaust gas inlet 1 connected to an exhaust gas
outlet of the engine and an exhaust gas second expansion chamber 4
having an exhaust gas outlet 3. A concave exhaust gas receiver 6
having a plurality of communicating holes 6b on a concave surface
6a which is disposed in the first expansion chamber 2 so that the
concave surface 6a faces to the exhaust gas inlet 1. Between the
first expansion chamber and the second expansion chamber, an
exhaust gas purifier 5 made of a honeycomb-like stainless steel
support body having innumerable small holes in an axial direction
and coated with the catalyst for purifying the exhaust gas. In FIG.
21 and FIG. 22, numerals `2a`, `4a` and `7` indicate a wall which
forms the first expansion chamber 2, a wall which forms the second
expansion chamber 4 and a partition plate which partitions the
first expansion chamber 2 and the second expansion chamber 4,
respectively.
[0004] Conventionally, various kinds of mufflers for small engines
have been developed. For example, a catalyst carrier for such a
muffler is made by laminating thin metal sheets each having a
number of openings with each surface of a cloth catalyst, and the
catalyst carrier is formed into a waveform shape and the plate side
is disposed in parallel with a flow direction of exhaust gas
(Patent document 1).
[0005] A conventional exhaust gas muffler as described hereunder is
known. The exhaust gas muffler accommodates a cylindrical shaped
cloth catalyst having a coarsely woven and a cylindrical shaped
cloth catalyst having a finely woven, therein. Each cylindrical
shaped cloth catalyst is comparatively soft, is made by coating a
catalyst onto a fabric and is formed into a cylindrical shape
having an oval cross-section. The coarsely woven cylindrical shaped
catalyst is disposed on an upper portion of the exhaust gas muffler
so as to surround two reinforcing beams, and an exhaust gas outlet
of an engine is communicated with an inside of the coarsely woven
cylindrical shaped catalyst through an opening of the exhaust gas
muffler. The finely woven cylindrical shaped catalyst is disposed
at a lower portion of the exhaust gas muffler so as to surround two
reinforcing beams, and so that a portion of an outer surface of the
finely woven cylindrical shaped catalyst contact closely with an
inner wall surface of the exhaust gas muffler. Accordingly, the
inside of the exhaust gas muffler is partitioned to a chamber
inside the coarsely woven cylindrical shaped catalyst, a chamber
outside the coarsely woven cylindrical shaped catalyst, a chamber
inside the finely woven cylindrical shaped catalyst and a chamber
in a lowermost portion outside the finely woven cylindrical shaped
catalyst. (Patent document 2)
[0006] Another conventional exhaust gas muffler as described
hereunder is known. In the exhaust gas muffler, a plurality of
catalyst carriers are connected in series in a flow passage of
exhaust gas. Each catalyst carrier is stacked with a support plate
having an opening and is covered with a wire mesh. One of the
catalyst carrier stacked with a support plate is fixed to an upper
housing of the exhaust gas muffler approximately horizontally. The
other catalyst carrier stacked with a support plate is fixed to a
lower housing of the exhaust gas muffler approximately
horizontally. The exhaust gas muffler is partitioned to three
chambers by the support plates. The wire mesh of the catalyst
carrier being at an exhaust gas inlet side has a coarse opening and
the wire mesh of the catalyst carrier being at an exhaust gas
outlet side has a fine opening. (Patent document 3)
[0007] Another conventional exhaust gas muffler as described
hereunder is known. An exhaust gas muffler of an
internal-combustion engine includes a box-like exhaust gas muffler
in which an inner exhaust gas muffler part and an outer exhaust gas
muffler part are detached with each other or integrated; a
communicating hole which is disposed in the exhaust gas muffler and
introduces exhaust gas being generated in the internal-combustion
engine to an inside of the exhaust gas muffler; and a tube member
composed of a reticulated material having a proper elasticity being
provided with a catalyst thereto. The tube member is disposed in a
space in the exhaust gas muffler so that a barrel of the tube is
held in such a direction as being clipped between the exhaust gas
muffler parts. According to the above mentioned exhaust gas muffler
structure, only if the tube member is disposed in the space between
the exhaust gas muffler parts when the inner and the outer exhaust
gas muffler parts are integrated, the tube member is retained so as
to fit with a surrounding configuration by barrel of the tube
elastically deforming freely. (Patent document 4)
[0008] Another conventional exhaust gas muffler as described
hereunder is known. A cylindrical spark arrestor which is means for
preventing sparks from splashing is composed of a cylindrical wire
mesh member. The cylindrical spark arrestor is retained in a state
being fixed between an end of a tail pipe and an inner surface of
an attaching body of the exhaust gas muffler. (Patent document
5)
[0009] Another conventional exhaust gas muffler as described
hereunder is known. A partition plate is disposed along an axial
direction of a cylinder of an engine in an exhaust gas muffler, and
an inside of the exhaust gas muffler is partitioned into a first
chamber near to an engine body and a second chamber distant from an
engine body. A catalyst is kept in a lower portion of the partition
plate. The catalyst having a function of re-burning unburned gas in
exhaust gas through oxidation reaction, is constituted by coating
the catalyst to a surface of a passage in a honeycomb structure
composed of a stainless steel. An inner catalyst cover which is
disposed on a position in the first chamber and covers about one
half inner side portion of the catalyst and an outer catalyst cover
which is disposed on a position in the second chamber and covers
about one half outer side portion of the catalyst, are attached to
the partition plate. A space surrounded by the inner catalyst cover
and the partition plate is a first catalyst chamber. An inlet side
communicating hole which communicates the first catalyst chamber
with the first chamber is formed on the inner catalyst cover. A
space surrounded by the outer catalyst cover and the partition
plate is a second catalyst chamber. An outlet side communicating
hole which communicates the second catalyst chamber with the second
chamber is formed on the outer catalyst cover. A catalyst
installing box in which the catalyst is installed is configured by
attaching the inner catalyst cover and the outer catalyst cover to
the partition plate. (Patent document 6)
[0010] Another conventional exhaust gas muffler as described
hereunder is known. An exhaust gas muffler is provided with an
expansion chamber into which exhaust gas being blown from an
exhaust gas outlet of an internal combustion engine is introduced.
A peripheral part of the expansion chamber comprises a double wall
structure composing an inner wall panel and an outer wall panel
being isolated with a distance so as to form a space between the
panels. An inlet of the exhaust gas which introduces the exhaust
gas in the expansion chamber into the space is formed on the inner
wall panel, an outlet of the exhaust gas which exhausts the exhaust
gas from the space to an outside is formed on the outer wall panel,
and a spark arrestor screen is disposed so as to cover the outlet
of the exhaust gas. A cylindrical oxidation catalyst composed of a
metal carrier is disposed as an exhaust gas purifier so as to
protrude in each of the first expansion chamber and the second
expansion chamber. (Patent document 7)
[0011] Another conventional catalyst muffler as described hereunder
is known. A catalyst muffler is divided into a body housing and a
lid housing. Each of a ceramic cloth, a cloth catalyst and a wire
mesh made of a stainless steel is formed so as to adjust closely to
the three-dimensional configuration of each housing, and the
ceramic cloth, the cloth catalyst and the wire mesh made of the
stainless steel are stacked in turn and joined to the whole the
inner surface of each housing. (Patent document 8)
[0012] A conventional muffler as described hereunder is known. A
general-purpose muffler for an internal combustion engine is made
by pinching and clamping a periphery of a separator along a joint
surface of an upper housing and a lower housing being divided up
and down. An inner space of the muffler is partitioned by the
separator. An inlet opening and an outlet opening which
communicates the first and the second chambers partitioned by the
separator with an exhaust port of the internal combustion engine
and to an outside air respectively are disposed in the muffler. A
cylindrical member having a small hole or a clearance is attached
to the inlet opening in the first chamber, and the cylindrical
member is provided with an exhaust gas purifying catalyst. (Patent
document 9)
[0013] Patent document 1: Japanese Laid-Open Patent Application
Publication No. 06-248939 (refer to paragraphs 0012 and 0014, and
FIG. 2)
[0014] Patent document 2: Japanese Laid-Open Patent Application
Publication No. 06-66137 (refer to paragraphs 0010 and 0011, and
FIG. 2)
[0015] Patent document 3: Japanese Laid-Open Patent Application
Publication No. 06-33754 (refer to paragraph 0010, and FIG. 1)
[0016] Patent document 4: Japanese Laid-Open Patent Application
Publication No. 07-293231 (refer to paragraphs 0010 and 0012, and
FIG. 1 and FIG. 2)
[0017] Patent document 5: Japanese Laid-Open Utility Model
Application Publication No. 07-40648 (refer to FIG. 3 and FIG.
4)
[0018] Patent document 6: Japanese Laid-Open Patent Application
Publication No. 2002-242666 (refer to paragraphs 0034, 0035 and
0036, and FIG. 1)
[0019] Patent document 7: Japanese Laid-Open Patent Application
Publication No. 10-8942 (refer to paragraphs 0006, 0014 and 0024,
and FIG. 1 and FIG. 2)
[0020] Patent document 8: Japanese Laid-Open Utility Model
Application Publication No. 06-18617 (refer to claims, and FIG. 1
and FIG. 2)
[0021] Patent document 9: Japanese Laid-Open Utility Model
Application Publication No. 05-21114 (refer to claims, and FIG. 1
and FIG. 2)
[0022] However, in a conventional muffler of an engine as shown in
FIG. 21, for example, because the exhaust gas purifier 5 is
constituted by the honeycomb-like stainless steel support body
coated with the catalyst for purifying exhaust gas, there is a
problem that the manufacturing process is complicated and that a
manufacturing cost is high.
[0023] Further, though the exhaust gas receiver 6 which is a
component of a conventional improved muffler is formed to the
concave shape and a plurality of communicating holes 6a are bored
on the concave surface 6a as shown in FIG. 22, no function for
purifying the exhaust gas is not provided therewith.
[0024] The exhaust gas muffler of a 2-stroke engine as described in
the patent document 1 includes the catalyst carrier. The catalyst
carrier is made by laminating thin metal sheets each having
numerous openings with each surface of the cloth catalyst. The
catalyst carrier is formed into the waveform shape and the plate
side is disposed in parallel with a flow direction of the exhaust
gas. There is a problem that a manufacturing process is complicated
and that the manufacturing cost is high.
[0025] In the exhaust gas muffler of a 2-stroke engine as described
in the patent document 2, because the exhaust gas inlet is not
provided with the heat resistant mesh catalyst and the exhaust gas
outlet is not provided with the heat resistant mesh catalyst, there
is a possibility that sparks blow out from the exhaust gas outlet
when the engine is under operation.
[0026] In the exhaust gas muffler of a 2-stroke engine as described
in the patent document 3, because the exhaust gas inlet is not
provided with the heat resistant mesh catalyst and the exhaust gas
outlet is not provided with the heat resistant mesh catalyst, there
is a possibility that sparks blow out from the exhaust gas outlet
while the engine is under operation.
[0027] In the exhaust gas muffler as described in the patent
document 4, the inside of the exhaust gas muffler is not
partitioned to the first expansion chamber, the second expansion
chamber and the third expansion chamber by the partition plate, a
muffling effect is not as good as expected.
[0028] In the muffler for an engine as described in the patent
document 5, because the cylindrical spark arrestor made of the
cylindrical wire mesh is retained in a state fixed between the end
of the tail pipe and the inner surface of the attaching body of the
exhaust gas muffler, it is difficult to replace the spark arrestor
with a new one.
[0029] In the exhaust gas muffler for a small engine as described
in the patent document 6, because the catalyst which has a function
of re-burning the unburned gas in the exhaust gas through the
oxidation reaction, by coating the catalyst to the surface of the
passage in the honeycomb structure composed of the stainless steel,
a manufacturing process is complicated and a manufacturing cost is
high.
[0030] In the exhaust gas muffler for a small engine as described
in the patent document 7, while the cylindrical oxidation catalyst
composed of the metal carrier is disposed as an exhaust gas
purifier so as to protrude in the first expansion chamber and the
second expansion chamber, there is a problem that a manufacturing
cost of the cylindrical oxidation catalyst is high. Meanwhile,
because between the inner wall panel and the outer wall panel which
form the double wall part, the exhaust gas flows to the outlet
opening disposed on the outer wall panel and the outer wall panel
is heated thereby, there is a problem that the double wall part
does not have an effect preventing the outer wall of the muffler
from being heated.
[0031] In the catalyst muffler as described in the patent document
8, because the inside of the muffler is not partitioned to the
first expansion chamber, the second expansion chamber and the third
expansion chamber by the partition plate, a muffling effect is not
good. Further, because the muffler is partitioned to two parts of
the body housing and the lid housing, and the ceramic cloth, the
cloth catalyst and the wire mesh made of the stainless steel are
stacked in turn and joined to whole the inner surface of each
housing, there is a problem that a structure of the catalyst in the
muffler is complicated and a manufacturing cost is high.
[0032] In a silencer as described in the patent document 9, because
a separator which divides the silencer to two parts is not provided
with a catalyst for purifying exhaust gas, there is a problem that
a purifying effect on the exhaust gas is insufficient.
DISCLOSURE OF THE INVENTION
[0033] A muffler for a small engine according to one embodiment of
the present invention includes: a first expansion chamber (12)
having an exhaust gas inlet (11) being connected to an exhaust gas
outlet of an engine; a second expansion chamber (15) for exhaust
gas being partitioned from the first expansion chamber (12) by a
partition plate (14) and being communicated with the first
expansion chamber (12) through a first communicating hole (13) on
the partition plate (14); and a third expansion chamber (18) for
the exhaust gas having an exhaust gas outlet (17), being
partitioned from the second expansion chamber (15) by the partition
plate (14) and being communicated with the second expansion chamber
(15) through a second communicating hole (16) on the partition
plate (14). A first heat resistant mesh catalyst (19) is disposed
on the exhaust gas inlet (11). A first exhaust gas purifier (20)
composed of a heat resistant knit fabric (20a) coated with a
catalyst for purifying the exhaust gas is disposed on the first
communicating hole (13) on the partition plate (14).
[0034] Further, in the muffler, the first exhaust gas purifier (20)
can be composed of the heat resistant knit fabric (20a) coated with
the catalyst for purifying the exhaust gas, supported with a heat
resistant cover (20b) having at least one exhaust gas inlet
(20d).
[0035] Further, in the muffler, the first exhaust gas purifier (20)
is disposed on an exhaust gas inlet side of the communicating hole
(13) on the partition plate (14), a second heat resistant mesh
catalyst (22) and a heat resistant cover having a plurality of
exhaust gas outlets (22a) are disposed on an exhaust gas outlet
side thereof, and a third heat resistant mesh catalyst (23) can be
disposed replaceably on the exhaust gas outlet (17).
[0036] Further, in the muffler, the first exhaust gas purifier (20)
can be composed of the heat resistant knit fabric (20a) coated with
the catalyst for purifying the exhaust gas, supported with a cover
(20c) made of a heat resistant mesh.
[0037] Further, in the muffler, at least an outer wall of the
second expansion chamber (15) which is not disposed on a side where
the muffler is attached can be composed of a double wall structure
of walls (15a', 15b).
[0038] Further, in the muffler, at least the outer wall of the
second expansion chamber (15) which is not disposed on the side
where the muffler is attached can be composed of the double wall
structure of walls (15a', 15b) and an heat insulator 15c can be
packed to the space between the double wall structure of walls
(15a', 15b).
[0039] Further, in the muffler, an exhaust gas receiver (24) is
disposed in the first expansion chamber (12) disposed opposite the
exhaust gas inlet (11). The exhaust gas receiver (24) is connected
to the exhaust gas inlet (11) and is provided with an exhaust gas
outlet (24b) disposed opposite the exhaust gas inlet (11). A second
exhaust gas purifier (25) which is composed of the heat resistant
knit fabric coated with the catalyst for purifying the exhaust gas
is installed on the exhaust gas outlet (24b) in the exhaust gas
receiver (24). An inclined surface (24a) can be disposed on the
exhaust gas outlet (24b) so that the exhaust gas flows in a
direction toward the first exhaust gas purifier (20).
[0040] Further, in the muffler, the first heat resistant mesh
catalyst (19) can be made of a SUS310S stainless steel mesh coated
with the catalyst for purifying the exhaust gas.
[0041] Further, in the muffler, the second heat resistant mesh
catalyst (21) can be made of the SUS310S stainless steel mesh
coated with the catalyst for purifying the exhaust gas. The heat
resistant cover (22) can be made of a SUS310S stainless steel
sheet. The third heat resistant mesh catalyst (23) can be made of
the SUS310S stainless steel mesh coated with the catalyst for
purifying the exhaust gas.
[0042] Further, in the muffler, the exhaust gas receiver (24) can
be made of the SUS310S stainless steel sheet.
[0043] Further, a muffler for a small engine according to another
embodiment, includes: a first expansion chamber (12) for exhaust
gas having an exhaust gas inlet (11) being connected to an exhaust
gas outlet of the engine; a second expansion chamber (15) which is
partitioned from the first expansion chamber (12) by a partition
plate (14); and a third expansion chamber (18) having an exhaust
gas outlet (17) being communicated with the second expansion
chamber (15) through a second communicating hole (16) on the
partition plate (14). A first heat resistant mesh catalyst (19) is
disposed on the exhaust gas inlet (11). A convex part (14b) having
at least one first communicating hole (14a) and protruding toward
the first expansion chamber (12) is made in an integral molding
manner. A first exhaust gas purifier (20) composed of a heat
resistant knit fabric (20a) coated with a catalyst for purifying
the exhaust gas is installed to a concave side of a convex part
(14b) disposed opposite the second expansion chamber (15). A heat
resistant cover (22) having the exhaust gas outlet (22a) is
disposed for covering the first exhaust gas purifier (20) in a
direction from a side of the second expansion chamber (15).
[0044] A muffler for a small engine according to further another
embodiment, includes: a first expansion chamber (12) for exhaust
gas having an exhaust gas inlet (11) being connected to the exhaust
gas outlet of the engine; a second expansion chamber (15) which is
partitioned from the first expansion chamber (12) by a partition
plate (14); and a third expansion chamber (18) having an exhaust
gas outlet (17) being communicated with the second expansion
chamber (15) through a second communicating hole (16) on the
partition plate (14). A first heat resistant mesh catalyst (19) is
disposed on the exhaust gas inlet (11). A convex part (14d) having
an exhaust gas outlet (14c) and protruding toward the second
expansion chamber (15) is made in an integral molding manner. An
exhaust gas purifier (20) composed of a heat resistant knit fabric
(20a) coated with a catalyst for purifying the exhaust gas is
installed on an exhaust gas inlet side on the side of the first
expansion chamber (12) of the convex part (14b). A heat resistant
cover (20b) having at least one exhaust gas outlet (20d) is
disposed for covering the first exhaust gas purifier (20) from the
first expansion chamber (12).
[0045] The muffler for a small engine according to further another
embodiment, includes: the first expansion chamber (12) for the
exhaust gas having the exhaust gas inlet (11) being connected to
the exhaust gas outlet of the engine; and the second expansion
chamber (15) being partitioned from the first expansion chamber
(12) by the partition plate (14) having the first communicating
hole (13). The first heat resistant mesh catalyst (19) is disposed
on the exhaust gas inlet (11). The first exhaust gas purifier (20)
composed of the heat resistant knit fabric (20a) coated with the
catalyst for purifying the exhaust gas is disposed on the first
communicating hole (13) on the partition plate (14). An outside air
suction pipe (30) is disposed through the second expansion chamber
(15). A portion of the outside air suction pipe facing to the first
exhaust gas purifier (20) is composed of a double pipe. An end of
the outside air suction pipe penetrates an outer wall and is
communicated with an outside air. A plurality of suction holes
(30b) are bored on an outer pipe of a double pipe (30a). The other
end of the outside air suction pipe (30) is communicated with the
exhaust gas outlet (17) through an exhaust gas guide (33).
[0046] In further another embodiment of the muffler for a small
engine according to the present invention, the exhaust gas guide
(33) is provided with a pipe (34) being communicated with the first
expansion chamber (12) of the exhaust gas and having a check valve
(35).
[0047] In further another embodiment of the muffler for a small
engine according to the present invention, the muffler includes:
the first expansion chamber (12) of the exhaust gas having the
exhaust gas inlet (11) being connected to the exhaust gas outlet of
the engine; and the second expansion chamber (15) partitioned from
the first expansion chamber (12) by the partition plate (14) having
the communicating hole (13). The first heat resistant mesh catalyst
(19) is disposed on the exhaust gas inlet (11). The first exhaust
gas purifier (20) composed of the heat resistant knit fabric (20a)
coated with the catalyst for purifying the exhaust gas is disposed
on the first communicating hole (13) on the partition plate (14).
The exhaust gas guide (33) which communicates the second expansion
chamber (15) with the exhaust gas outlet (17), is provided with the
pipe (34) being also communicated with the first expansion chamber
(12) of the exhaust gas and having the check valve (35).
[0048] According to further another embodiment of the muffler for a
small engine of the present invention, in the muffler according to
the one embodiment, another embodiment and further another
embodiments of the present invention, a concave groove (31) being
communicated with the third expansion chamber (18) at an end and
the outside air at the other end is formed on an outer surface of
the muffler, and a groove cover (32) covers the concave groove
(31).
[0049] According to further another embodiment of the muffler for a
small engine of the present invention, in the muffler according to
the one embodiment, another embodiment and further another
embodiments of the present invention, an outside air suction pipe
(30') being opened at each end is fixed along the outer wall of the
muffler so as to communicate with the exhaust gas outlet (17) at an
end and the outside air at the other end.
BRIEF DESCRIPTION OF THE DRAWINGS
[0050] FIG. 1 is a cross-sectional view according to one embodiment
of a muffler for a small engine of the present invention.
[0051] FIG. 2 is an exploded perspective view according to the one
embodiment of the muffler for a small engine of the present
invention.
[0052] FIG. 3 is an assembling perspective view according to the
one embodiment of the muffler for a small engine of the present
invention.
[0053] FIG. 4 is a cross-sectional view of the muffler in which a
first exhaust gas purifier according to the one embodiment of the
muffler for a small engine of the present invention is modified to
another embodiment.
[0054] FIG. 5 is an exploded perspective view of the muffler in
which the first exhaust gas purifier according to the one
embodiment of the muffler for a small engine of the present
invention is modified to the another embodiment.
[0055] FIG. 6 is an assembling perspective view of the muffler in
which the first exhaust gas purifier according to the one
embodiment of the muffler for a small engine of the present
invention is modified to the another embodiment.
[0056] FIG. 7 is a cross-sectional view of a muffler having an
outer wall composed of a double-wall structure, in a configuration
according to the one embodiment of the muffler for a small engine
of the present invention.
[0057] FIG. 8 is a cross-sectional view of the muffler in which a
heat insulator is packed in a space between the double walls of the
outer wall, in the configuration as shown in FIG. 7.
[0058] FIG. 9 is a cross-sectional view of the muffler in which the
first exhaust gas purifier is modified to another embodiment, in
the configuration as shown in FIG. 7.
[0059] FIG. 10 is a cross-sectional view of the muffler in which a
heat insulator is packed between the double walls of the outer
wall, in the configuration as shown in FIG. 9.
[0060] FIG. 11 is a cross-sectional view according to another
embodiment of a muffler for a small engine of the present
invention.
[0061] FIG. 12 is a cross-sectional view of the muffler in which
the first exhaust gas purifier is modified to another embodiment,
in the configuration as shown in FIG. 11.
[0062] FIG. 13 is a cross-sectional view according to further
another embodiment of a muffler for a small engine of the present
invention.
[0063] FIG. 14 is a cross-sectional view according to further
another embodiment of the muffler for a small engine of the present
invention.
[0064] FIG. 15 is a cross-sectional view according to further
another embodiment of the muffler for a small engine of the present
invention.
[0065] FIG. 16 is a cross-sectional view according to further
another embodiment of the muffler for a small engine of the present
invention.
[0066] FIG. 17 is a cross-sectional view according to further
another embodiment of the muffler for a small engine of the present
invention.
[0067] FIG. 18 is an exploded perspective view according to further
another embodiment of the muffler for a small engine of the present
invention.
[0068] FIG. 19 is an exploded perspective view according to further
another embodiment of the muffler for a small engine of the present
invention.
[0069] FIG. 20 is an exploded perspective view according to further
another embodiment of the muffler for a small engine of the present
invention.
[0070] FIG. 21 is a cross-sectional view of a conventional muffler
for a small engine.
[0071] FIG. 22 is a cross-sectional view of another conventional
muffler for a small engine.
BEST MODES FOR CARRYING OUT THE INVENTION
[0072] Hereunder, a detailed description is made referring to the
drawings on the embodiments of the present invention.
[0073] FIG. 1 is a cross-sectional view according to one embodiment
of a muffler for a small engine of the present invention. FIG. 2 is
an exploded perspective view thereof and FIG. 3 is an assembling
perspective view thereof.
[0074] The muffler for a small engine according to the one
embodiment of the present invention includes: a first expansion
chamber 12 having an exhaust gas inlet 11 being connected to an
exhaust gas outlet of the engine; a second expansion chamber 15 for
exhaust gas partitioned from the first expansion chamber 12 by a
partition plate 14 and communicated with the first expansion
chamber 12 through a first communicating hole 13 on the partition
plate 14; and a third expansion chamber 18 for the exhaust gas
having an exhaust gas outlet 17, partitioned from the second
expansion chamber 15 by the partition plate 14 and communicated
with the second expansion chamber 15 through a second communicating
hole 16 on the partition plate 14. A first heat resistant mesh
catalyst 19 is disposed on the exhaust gas inlet 11. A first
exhaust gas purifier 20 composed of a heat resistant knit fabric
20a coated with a catalyst for purifying the exhaust gas is
disposed on the first communicating hole 13 on the partition plate
14.
[0075] The first exhaust gas purifier 20 is composed of the heat
resistant knit fabric 20a coated with the catalyst for purifying
the exhaust gas, supported with a heat resistant cover 20b having
at least one exhaust gas inlet 20d.
[0076] The first exhaust gas purifier 20 is disposed on an exhaust
gas inlet side of the first communicating hole 13 on the partition
plate 14, a second heat resistant mesh catalyst 21 and a heat
resistant cover 22 having a plurality of exhaust gas outlets 22a
are disposed on an exhaust gas outlet side thereof, and the third
heat resistant mesh catalyst 23 can be disposed replaceably on the
exhaust gas outlet 17.
[0077] The heat resistant cover 20b and the heat resistant cover 22
can be made by press forming a stainless steel sheet and are welded
with the partition plate 14 around the first communicating hole
13.
[0078] An outer wall 12a of the first expansion chamber 12, an
outer wall 15a of the second expansion chamber 15, the partition
plate 14, and a partition plate 18a which is disposed between the
partition plate 14 and the outer wall 12a of the first expansion
chamber 12 by welding and constitutes the third expansion chamber
18, are made by forming a stainless steel sheet.
[0079] Among stainless steel materials, SUS310S stainless steel is
preferred for making the outer wall 12a of the first expansion
chamber 12, the outer wall 15a of the second expansion chamber 15,
the partition plate 14, the partition plate 18a which constitutes
the third expansion chamber 18, the heat resistant cover 20b and
the heat resistant cover 22c. If SUS310S stainless steel is used
for them, each life can be extended due to the excellent heat
resistant and acid resistant properties.
[0080] Further, the first heat resistant mesh catalyst 19, the
second heat resistant mesh catalyst 21 and the third heat resistant
mesh catalyst 23 can be made of a stainless steel wire mesh or a
stainless steel sheet having a number of fine holes bored, coated
with a catalyst such as one or a combination of platinum, rhodium,
palladium, etc., for purifying the exhaust gas. If the SUS310S
stainless steel is used preferably as the stainless steel material,
each life can be extended due to the excellent heat resistant and
acid resistant properties.
[0081] Further, the heat resistant knit fabric 20a is made of a
fabric being knit from a piece of wire or a few pieces of wires of
a stainless steel and being folded to a pre-determined thickness,
and coated with the catalyst for purifying the exhaust gas.
[0082] A manufacturing process of the heat resistant knit fabric
20a is simpler and a manufacturing cost grows less, as compared to
the manufacturing process and the manufacturing cost of the
conventional stainless steel honeycomb-like substrate.
[0083] As shown in FIG. 1, FIG. 2 and FIG. 3, because an inside of
the muffler is partitioned into the first expansion chamber 12, the
second expansion chamber 15 and the third expansion chamber 18, by
the partition plate 14, its muffling effect improves. Further,
because the first heat resistant mesh catalyst 19 is disposed on
the exhaust gas inlet 11, sparks included in the exhaust gas of the
engine do not enter the muffler (so called, a spark arrestor
effect). Further, because the first exhaust gas purifier 20 which
is disposed on the first communicating hole 13 bored on the
partition plate 14 so as to communicate the first expansion chamber
12 with the second expansion chamber 15, is composed of the heat
resistant fabric 20a coated with the catalyst for purifying the
exhaust gas, the manufacturing process is simpler and a
manufacturing cost is reduced.
[0084] The second heat resistant mesh catalyst 21 is made of a
stainless steel mesh coated with the catalyst for purifying the
exhaust gas, and is welded to the partition plate 14. Further, the
third heat resistant mesh catalyst 23 is made of the stainless
steel mesh coated with the catalyst for purifying the exhaust gas.
If the SUS310S stainless steel is used preferably as the stainless
steel material, each life can be extended due to the excellent heat
resistant and acid resistant properties.
[0085] FIG. 4 is a cross-sectional view of the muffler in which the
first exhaust gas purifier 20 is modified to another embodiment.
FIG. 5 is an exploded perspective view and FIG. 6 is an assembling
perspective view. The first exhaust gas purifier 20 is composed of
the heat resistant knit fabric 20a coated with the catalyst for
purifying the exhaust gas, supported with the heat resistant cover
20c made of a heat resistant mesh. The heat resistant mesh can be
made by coating a stainless steel mesh with the catalyst for
purifying the exhaust gas, and the heat resistant cover 20c being
made as such is welded to the partition plate 14. If the SUS310S
stainless steel is used preferably as the stainless steel material,
a life can be extended thereby due to the excellent heat resistant
and acid resistant properties.
[0086] As described above, because the first exhaust gas purifier
20 is disposed on an inlet side of the exhaust gas of the first
communicating hole 13 bored through the partition plate 14, and the
second heat resistant mesh catalyst 21 and the heat resistant cover
22 having a plurality of the exhaust gas outlets 22a are disposed
on an outlet side, the first exhaust gas purifier 20 is heated up
fast and a temperature rises. Consequently, the exhaust gas is
purified better. Further, because the third heat resistant mesh
catalyst 23 is disposed replaceably on the exhaust gas outlet 17,
the sparks can be prevented from blowing out, and the third heat
resistant mesh 23 can be replaced easily.
[0087] As shown in FIG. 7 and FIG. 9, a wall of the second
expansion chamber 15 which is not at least a wall of the engine
side can be composed of a double wall structure of walls 15a',
15b.
[0088] Further, as shown in FIG. 8 and FIG. 10, the wall of the
second expansion chamber 15 which is no at least the wall of the
engine side can be composed of a double wall structure of walls
15a', 15b, and a heat insulator 15 can be packed to a space between
the double walls.
[0089] By the configuration as described above, the outer wall of
the muffler is prevented from being heated up. Further, because the
heat insulator 15c is packed into the space between the double
walls, an effect for preventing the outer wall of the muffler from
being heated up is high.
[0090] According to another embodiment of the present invention, as
shown in FIG. 11 and FIG. 12, an exhaust gas receiver 24 can be
disposed in the first expansion chamber 12 disposed opposite the
exhaust gas inlet 11 being connected to the exhaust gas outlet of
the engine. The exhaust gas receiver 24 is connected to the exhaust
gas inlet 11 and has an exhaust gas outlet 24b disposed opposite
the exhaust gas inlet 11. In the vicinity of the exhaust gas outlet
24b inside the exhaust gas receiver 24, a second exhaust gas
purifier 25 composed of the heat resistant knit fabric coated with
the catalyst is disposed. An inclined surface 24a is attached to
the exhaust gas outlet 24b and therefore the exhaust gas flows in a
direction toward the first exhaust gas purifier 20.
[0091] After installing the second exhaust gas purifier 25 in the
exhaust gas receiver 24, a center portion of the exhaust gas
receiver 24 is deformed so as to protrude inward, and the second
exhaust gas purifier 25 is fixed so as not to be detached.
[0092] By the configuration as described above, because a first
exhaust gas exhausted from the engine is received by the exhaust
gas receiver 24 and is purified by the second exhaust gas purifier
25 disposed therein, a purification effect on the exhaust gas is
better.
[0093] Further, because the first heat resistant mesh catalyst 19
is made of the SUS310S stainless steel mesh coated with the
catalyst for purifying the exhaust gas, a life of the first heat
resistant mesh catalyst 19 can be extended due to the excellent
heat resistant and acid resistant properties.
[0094] Further, because the second heat resistant mesh catalyst 21
is made of the SUS310S stainless steel mesh coated with the
catalyst for purifying the exhaust gas, the heat resistant cover 22
is made of the SUS310S stainless steel sheet and the third heat
resistant mesh catalyst 23 is made of the SUS310S stainless steel
mesh coated with the catalyst for purifying the exhaust gas, each
life of the second heat resistant mesh catalyst 21, the heat
resistant cover 22 and the third heat resistant mesh catalyst 23
can be extended due to the excellent heat resistant and acid
resistant properties.
[0095] Further, the exhaust gas receiver 24 is made of the SUS310S
stainless steel sheet, and the second exhaust gas purifier 25
composed of the stainless steel knit fabric coated with the
catalyst for purifying the exhaust gas is installed therein. Each
life of the exhaust gas receiver 24 and the second exhaust gas
purifier 25 is extended due to the excellent heat resistant and
acid resistant properties.
[0096] According to another embodiment of the muffler for a small
engine of the present invention, as shown in FIG. 13, a convex part
14b having at least one first communicating hole 14a and protruding
toward first expansion chamber 12 is made on the partition plate 14
in an integral molding manner. The first exhaust gas purifier 20
composed of the stainless steel knit fabric coated with the
catalyst for purifying the exhaust gas is installed to a concave
part on the side of the second expansion chamber (15) of the convex
part (14b), and the heat resistant cover 22 having the exhaust gas
outlet 22a covers the first exhaust gas purifier 20 from the second
expansion chamber 15. Consequently, the first exhaust gas purifier
20 can be manufactured at a lower cost due to a simpler
configuration. The exhaust gas outlet 22a is disposed so that the
exhaust gas does not flow in a direction toward the outer wall 15a
of the second expansion chamber 15, but flows along the partition
plate 14.
[0097] According to further another embodiment of a muffler for a
small engine of the present invention, as shown in FIG. 14, a
convex part 14d having an exhaust gas outlet 14c and protruding
toward second expansion chamber 15 is made on the partition plate
14 in an integral molding manner. The first exhaust gas purifier 20
composed of the stainless steel knit fabric 20a coated with the
catalyst for purifying the exhaust gas is installed to an inlet
side of the concave part of the convex part on the side of the
first expansion chamber (12), and the heat resistant cover 20b
having at least one exhaust gas inlet 20d covers the first exhaust
gas purifier 20 from the first expansion chamber 12. Consequently,
the first exhaust gas purifier 20 can be manufactured at a lower
cost due to a simpler configuration. The exhaust gas outlet 14c is
disposed so that the exhaust gas does not flow in a direction
toward the outer wall 15a of the second expansion chamber 15, but
flows along the partition plate 14.
[0098] In further another embodiment of the muffler for a small
engine according to the present invention, as shown in FIG. 15, the
first expansion chamber 12 for the exhaust gas having the exhaust
gas inlet 11 is connected to the exhaust gas outlet of the engine
and the second expansion chamber 15 is partitioned from the first
expansion chamber 12 by the partition plate 14 having the
communicating hole 13. The first heat resistant mesh catalyst 19 is
disposed on the exhaust gas inlet 11. The first exhaust gas
purifier 20 composed of the heat resistant knit fabric 20a coated
with the catalyst for purifying the exhaust gas is disposed on the
first communicating hole 13 on the partition plate 14. An outside
air suction pipe 30 is disposed through the second expansion
chamber 15. A portion of the outside air suction pipe 30 disposed
opposite the first exhaust gas purifier 20 is composed of a double
pipe. An end of the outside air suction pipe penetrates the outer
wall and is communicated with the outside air. A plurality of
suction holes 30b are bored on an outer pipe of the double pipe
30a. The other end of the outside air suction pipe 30 is
communicated with the exhaust gas outlet 17 through an exhaust gas
guide 33.
[0099] Meanwhile, in the embodiment as shown in FIG. 15, while the
exhaust gas purifier 20 is composed of the heat resistant knit
fabric 20a, supported with the heat resistant cover 20c made of the
heat resistant mesh, the exhaust gas purifier 20 can be
constituted, as shown in FIG. 1, by the heat resistant knit fabric
20a supported with the heat resistant cover 20b having at least one
exhaust gas inlet 20d.
[0100] Because such an outside air suction pipe 30 is disposed, the
exhaust gas passing through the first exhaust gas purifier 20
enters the outer pipe 30a through the suction holes 30b bored on
the outer pipe 30a of the double pipe portion of the outside air
suction pipe 30, and flows in a direction toward the exhaust gas
outlet 17. Consequently, because the exhaust gas in the outside air
suction pipe 30 is suctioned, the outside air enters the outside
air suction pipe 30 from an outside air suction inlet 30c at the
other end thereof and a temperature of the exhaust gas being
exhausted from the exhaust gas outlet 17 lowers.
[0101] In further another embodiment of the muffler for a small
engine according to the present invention, as shown in FIG. 16, a
pipe 34 is connected to the exhaust gas guide 33 so that it
communicates with the exhaust gas first expansion chamber 12, and a
check valve 35 is attached to the pipe 34.
[0102] The check valve 35 can be a butterfly valve as shown in FIG.
16 (b), and a top end portion of the pipe 34 can be formed to a
smaller size as shown in FIG. 16 (c).
[0103] Accordingly, because the outside air (oxygen) flows into the
first expansion chamber 12 through the check valve 35 attached to
the pipe 34, a burning efficiency of the exhaust gas while the
exhaust gas in the first expansion chamber 12 being burned in the
first exhaust gas purifier 20 is high, and further, because part of
the exhaust gas re-circulates into the first expansion chamber 12
and is re-burned in the first exhaust gas purifier 20, a purifying
effect on the exhaust gas is good.
[0104] In further another embodiment of the muffler for a small
engine according to the present invention, as shown in FIG. 17, the
first expansion chamber 12 of the exhaust gas having the exhaust
gas inlet 11 is connected to the exhaust gas outlet of the engine
and the second expansion chamber 15 is partitioned from the first
expansion chamber 12 through the partition plate 14 having the
communicating hole 13. The first heat resistant mesh catalyst 19 is
disposed on the exhaust gas inlet 11. The first exhaust gas
purifier 20 composed of the heat resistant knit fabric 20a coated
with the catalyst for purifying the exhaust gas is disposed on the
first communicating hole 13 on the partition plate 14. The exhaust
gas guide 33 which communicates the second expansion chamber 15
with the exhaust gas outlet 17, is provided with the pipe 34 which
is also communicated with the first expansion chamber 12 of the
exhaust gas and has the check valve 35.
[0105] Accordingly, because part of the exhaust gas in the second
expansion chamber 15 re-enters the first expansion chamber 12
through the pipe 34 and the check valve 35, and is re-burned in the
first expansion chamber 20, a purification effect on the exhaust
gas is good.
[0106] In further another embodiment of the muffler for a small
engine according to the present invention, as shown in FIG. 18, a
concave groove being communicated with the third expansion chamber
18 (refer to FIG. 1) at an end and with the outside air at the
other end is formed on an outer surface of the muffler, and a
groove cover 32 covers the concave groove 31. The exhaust gas is
exhausted from the third expansion chamber 18 through an exhaust
gas outlet 17. The outside air enters the third expansion chamber
18 through the concave groove 31 formed on the outer wall of the
muffler following the exhaust gas being exhausted. Therefore,
temperature of the exhaust gas being exhausted from the exhaust gas
outlet 17 lowers. Here, as shown in FIG. 19, the groove cover which
covers the concave groove 31 can be made in one member including a
lattice member 28' which covers the exhaust gas outlet 17 of the
third expansion chamber 18 and a groove cover 32' which covers the
concave groove 31.
[0107] In further another embodiment of the muffler for a small
engine according to the present invention, as shown in FIG. 20, an
outside air suction pipe 30' being opened at each end is fixed
along the outer wall of the muffler so as to communicate with the
exhaust gas outlet 17 at an end and the outside air at the other
end. Because the outside air enters the third expansion chamber 18
through the other end of the outside air suction pipe 30' following
the exhaust gas which is exhausted from the third expansion chamber
18 (refer to FIG. 1) through the exhaust gas outlet 17, temperature
of the exhaust gas being exhausted from the exhaust gas outlet 17
lowers. The outside air suction pipe 30' can be fixed along the
outer wall of the muffler by means such as welding, etc.
[0108] Further, as shown in FIG. 1, FIG. 3, FIG. 4, FIG. 6 and FIG.
11 to FIG. 17, each end portion of the outer walls 12a, 15a, and
the partition plate 14 is fixed by clamping.
[0109] Meanwhile, as shown in FIG. 7 to FIG. 10, each end portion
of the double-walls 12a, 12b, the partition plate 15 and the
double-walls 15a', 15b forming the second expansion chamber 15 is
fixed by clamping.
[0110] The numeral `26` is, as indicated in FIG. 1 to FIG. 6 and
FIG. 11 to FIG. 20, a pipe member which is disposed on a position
between the outer wall 12a forming the first expansion chamber 12
and the outer wall 15a forming the second expansion chamber 15, and
in which a bolt 27 for fixing the muffler to the engine is
inserted. The numeral `28`, as indicated in FIG. 1 to FIG. 6 and
FIG. 11 to FIG. 20, is a lattice member which is attached
replaceably to the outer wall 12a of the muffler using an attaching
screw. The third heat resistant mesh catalyst 23 can be replaced by
detaching the lattice member 28.
* * * * *