This application is based on and claims Convention priority to Japanese patent application No. 2015-242579, filed Dec. 11, 2015, the entire disclosure of which is herein incorporated by reference as a part of this application.
Field of the Invention
The present invention relates to a cooling structure in an exhaust muffler for decreasing the amount of noise emitted by the exhaust gases of a combustion engine.
Description of Related Art
JP Laid-open Patent Publication No. H09-228836, for example, discloses an engine system including a cooling fan adapted to be driven in association with an engine rotary shaft so that an engine cylinder can be cooled by a cooling air or air, in which a portion of the cooling air from the cooling fan is guided to cool an outer surface of a muffler.
It has, however, been found that with the cooling structure disclosed in the JP Laid-open Patent Publication No. H09-228836 referred to above, difficulty has been found in guiding the cooling air efficiently over the entire outer surface of the muffler. It has also been found that mere cooling of the outer surface is far from sufficiently cooling the muffler to the deepest region of the interior thereof.
In view of the foregoing, the present invention has been devised to provide a muffler for use with an engine, which muffler has a high cooling performance.
In order to accomplish the foregoing object, the muffler in accordance with one aspect of the present invention is a muffler for decreasing an amount of noise emitted by the exhaust gases of an engine, which muffler is provided with a cooling member configured to flow an external air through the muffler. The cooling member referred to above is, for example, a pipe.
According to the above discussed aspect of the present invention, the cooling member extends through a peripheral wall of the muffler, and an external air is allowed to pass through the cooling member. Accordingly, in addition to the outer surface of the muffler, the interior of the muffler can be effectively cooled. As a result thereof, the cooling performance of the muffler increases. With the cooling performance increased in the manner described above, it is possible to use, for example, a material relatively low in heat resistance and/or to reduce the plate thickness for a member constituting the peripheral wall of the muffler, resulting in an increase of the degree of freedom in designing.
In one preferred embodiment of the present invention, the cooling member referred to above may extend through a first expansion chamber on the most upstream side. According to this structural feature, the first expansion chamber in the muffler, where the highest possible temperature is attained, can be effectively cooled.
Where the cooling member referred to above extends through the first expansion chamber, a catalyst for substantially purifying the exhaust gases may be disposed between the first expansion chamber and a second expansion chamber on one side downstream thereof. If the catalyst is disposed between the first expansion chamber and the second expansion chamber, the first expansion chamber is further heated to a higher temperature along with the heating of the second expansion chamber, but this structural feature allows the first expansion chamber of the elevated temperature to be effectively cooled.
In another preferred embodiment of the present invention, the cooling member referred to above may extend in a direction conforming to a direction of flow of a cooling air from a cooling fan of the engine. According to this structural feature, since the cooling member extends in a direction conforming to the direction of flow of the cooling air, the cooling air can be effectively guided into the cooling member. As a result, the cooling performance of the muffler is increased.
In a further preferred embodiment of the present invention, an exhaust pipe having a downstream end closed may be connected while extending through a peripheral wall of the muffler, in which case a discharge port open into the muffler may be formed in a peripheral wall of the exhaust pipe, and the cooling member may be disposed in contact with or in the vicinity of the exhaust pipe. It is to be noted that the wording “the cooling member in the vicinity of the exhaust pipe” referred to above and hereinafter is intended to mean that the distance between the cooling member and the exhaust pipe is equal to or smaller than half the external diameter of the exhaust pipe. According to this structural feature, the exhaust pipe tending to have the elevated temperature and its vicinity can be effectively cooled.
In a further preferred embodiment of the present invention, the cooling member may be formed by a pipe. According to this structural feature, the cooling member can be easily produced.
In a still further preferred embodiment of the present invention, the engine may be provided with a carburetor. Where the carburetor type engine is not provided with a fuel cutting function that works at the time the engine is halted, afterburning phenomenon may be likely to occur in which unburned components of the fuel is burned at a high temperature zone within the muffler when the engine is halted. According to this structural feature, the occurrence of the afterburning phenomenon can be effectively avoided, since the interior of the muffler is cooled as well.
Any combination of at least two constructions, disclosed in the appended claims and/or the specification and/or the accompanying drawings should be construed as included within the scope of the present invention. In particular, any combination of two or more of the appended claims should be equally construed as included within the scope of the present invention.
In any event, the present invention will become more clearly understood from the following description of preferred embodiments thereof, when taken in conjunction with the accompanying drawings. However, the embodiments and the drawings are given only for the purpose of illustration and explanation, and are not to be taken as limiting the scope of the present invention in any way whatsoever, which scope is to be determined by the appended claims. In the accompanying drawings, like reference numerals are used to denote like parts throughout the several views, and:
Hereinafter a preferred embodiment of the present invention will be described in detail with particular reference to the accompanying drawings. In particular,
As shown in
The combustion engine employed in the practice of the preferred embodiment is an engine of a carburetor type. In other words, a carburetor 10 for mixing a fuel and an air together and then injecting the resultant air-fuel mixture into a combustion chamber within the engine cylinder 5 is fluid connected with an intake port (not shown) defined in a rear portion of the engine cylinder 5. On the other hand, a muffler 14 is fluid connected through an exhaust pipe 12 with an exhaust port (not shown) defined at a front portion of the engine cylinder 5. The muffler 14 operates to decrease the noise emitted by exhaust gases G of the combustion engine E.
The exhaust pipe 12 is in the form of a pipe made of a steel material and is fluid connected with the muffler 14 after extending forwardly from the engine cylinder 5 and being then curved substantially 90° in a rightward direction. In other words, the muffler 14 is disposed forwardly of and on a right side of the engine cylinder 5. The exhaust pipe 12 has an outer periphery covered by an exhaust pipe covering 16. Specifically, the exhaust pipe covering 16 covers regions upwardly, downwardly, forwardly and leftwardly of the exhaust pipe 12. This exhaust pipe covering 16 is fitted to fitting metal pieces 18 (best shown in
The muffler 14 is of a cylindrical shape having its axis A1 extending substantially in a vertical direction. As shown in
The muffler covering 28 covers a region upwardly and approximately half of the outer periphery of the muffler main body portion 26 and, more specifically, a region forwardly and a region rightwardly of the muffler main body portion 26 as shown in
As shown in
The first expansion chamber 46 is a space delimited by the top lid 38, the tubular body 36 and the first partition wall 42. The second expansion chamber 48 is a space delimited by the tubular body 36 and the first and second partition walls 42 and 44. The first and second expansion chambers 46 and 48 cooperate with each other to form the silencing chamber 25 referred to previously. The resonance chamber 50 is a space delimited by the bottom lid 40, the tubular body 36 and the second partition wall 44. It is, however, to be noted that the resonance chamber 50 may not be necessarily employed and may therefore be dispensed with.
The first partition wall 42 has a first throughhole 42a defined therein, and a first communicating passage 61 is formed by a pipe 51, inserted in the first throughhole 42a, to thereby fluid connect the first expansion chamber 46 and the second expansion chamber 48 with each other. In the practice of the embodiment now under discussion, the pipe 51 is welded to the first partition wall 42, and a catalytic converter 52 for substantially purifying the exhaust gases G is inserted in the first communicating passage 61 within the pipe 51. It is, however, to be noted that the use of the catalytic converter 52 is not necessarily essential and may therefore be dispensed with.
The second partition wall 44 has a second throughhole 44a defined therein, and a second communicating passage 62 is formed by a tail pipe 54, inserted in the second communicating hole 44a, to communicate the second expansion chamber 48 with the outside. The tail pipe 54 is secured to the second partition wall 44 by means of any known welding technique. The tail pipe 54 extends through the resonance chamber 50 and then through the bottom lid 40 so as to protrude towards the outside of the muffler main body portion 26, with an outer end thereof defining the outflow port 24 of the muffler 14. A region of a peripheral wall of the tail pipe 54, which extends through the resonance chamber 50, is formed with a plurality of third communicating holes 54a in communication with the resonance chamber 50.
The exhaust pipe 12 has a downstream portion 12a which extends through the peripheral wall of the tubular muffler 14, that is, one side portion (left side portion) of the tubular body 36. The downstream portion 12a is connected with the muffler main body portion 26. The downstream portion 12a of the exhaust pipe 12 extends slantwise downwardly within the interior of the muffler main body portion 26, specifically downwardly towards the other side portion (right side portion) of the first expansion chamber 46. A portion of a downstream end of the exhaust pipe 12 extends through the other side portion (right side portion) that is opposed to one side portion of the tubular body 36. The downstream end of the exhaust pipe 12 is closed by a closure member 56. The closure member 56 is in the form of, for example, a metal plate and is secured to the downstream end of the exhaust pipe 12 by means of any known securing technique such as welding.
At a site of the peripheral wall of the exhaust pipe 12 that is positioned within the first expansion chamber 46, a discharge port 58 is provided in communication with the first expansion chamber 46. The discharge port 58 communicates the interior of the exhaust pipe 12 with the first expansion chamber 46. The downstream portion 12a of the exhaust pipe 12 is secured to a left side portion and a right side portion of the tubular body 36 by means of any known welding technique. The discharge port 58 is formed in a lower portion of the downstream portion 12a of the exhaust pipe 12 so as to confront with the first partition wall 42.
As shown in
It is, however, to be noted that the cooling member referred to above may not necessarily limited to the cylindrical pipe, provided that it is of a structure capable of feeding the cooling air W into the interior of the muffler 14 through the muffler main body 26. It is also to be noted that the cooling member may be a pipe of a kind having a transverse section, which is oval, rectangular, polygonal or any other shape, and that the use may be made of, for example, different members for the interior and the outside of the muffler 14, respectively, which different members are to be connected together by means of any known welding technique. Yet, the cooling member may be constituted by a plurality of members and, for example, the interior and the outside of the muffler main body portion 26 may be prepared from different members which have to be connected together by means of any known welding technique. In such case, the cooling member may be curved within the interior of the muffler main body portion 26 or the passage sectional area thereof may not be fixed.
The cooling pipe 60 extends in a direction conforming to the direction of flow of the cooling air W and, in the practice of the embodiment now under discussion, the cooling pipe 60 extends slantwise downwardly towards the right side. Also, the cooling pipe 60 is disposed in the vicinity of the exhaust pipe 12. It is to be noted that the wording “the cooling member in the vicinity of the exhaust pipe” referred to above and hereinafter is intended to mean that the distance d1 between the cooling pipe 60, shown in
In the practice of the embodiment now discussion, the exhaust pipe 12 and the cooling pipe 60 are so disposed as to be parallel to each other. It is, however, to be noted that the present invention works satisfactorily provided that the exhaust pipe 12 and the cooling pipe 60 extend parallel to each other when viewed at least from above such as in
When the combustion engine E shown in
After the exhaust gases G has been again expanded within the second expansion chamber 48, the exhaust gases G flow through the tail pipe 54 and are then discharged to the outside of the muffler 14. At this time, a portion of the exhaust gases G is discharged to the resonance chamber 50 through the third communicating hole 54a with the exhaust pulses consequently relieved.
On the other hand, when the combustion engine E shown in
As shown in
In the construction as hereinabove described, the flow of the cooling air W through the cooling pipe 60 shown in
In the practice of the embodiment now under discussion, it has been found that the internal temperature of the first expansion chamber 46, which has been about 250° C. when the outside temperature was 25° C., was decreased by about 60° thanks to the use of the cooling pipe 60. Consequent upon the increase of the cooling performance of the muffler 14 as hereinbefore discussed, it is possible to use a material having a relatively low heat resistance for the plate member forming the muffler main body portion 26 and to reduce the plate thickness of the plate member forming the muffler main body portion 26 and, hence, the degree of freedom of designing increases.
Also, the cooling pipe 60 extends through the first expansion chamber 46 on the most upstream side. Since the first expansion chamber 46 is a region where the highest temperature is attained within the interior of the muffler main body portion 26, the use of the cooling pipe 60 in the first expansion chamber of that kind referred to above is beneficial to allow the muffler main body portion 26 to be cooled effectively.
Also, since the catalytic converter 52 is disposed between the first expansion chamber 46 and the second expansion chamber 48, in addition to the second expansion chamber 48 attaining the high temperature, the first expansion chamber 46 is further heated to a high temperature. However, the use of the cooling pipe 60 in the manner described above is effective to cool the first expansion chamber 46, then at the elevated temperature.
The cooling pipe 60 extends in a direction conforming to the direction of flow of the cooling air W. Accordingly, the cooling air W can be efficiently introduced into the interior of the cooling pipe 60. As a result thereof, the cooling performance of the muffler 14 is further increased.
Yet, since the cooling pipe 60 is disposed in the vicinity of the exhaust pipe 12, the exhaust pipe 12 and its vicinity, where a high temperature is attained, can be cooled effectively.
The combustion engine E shown in
Although the present invention has been fully described in connection with the preferred embodiments thereof with reference to the accompanying drawings which are used only for the purpose of illustration, those skilled in the art will readily conceive numerous changes and modifications within the framework of obviousness upon the reading of the specification herein presented of the present invention. By way of example, although in describing the preferred embodiment of the present invention the use of two silencing chambers 25 has been shown and described, the present invention is not necessarily limited thereto and the only silencing chamber or three or more silencing chambers can be used. Also, the use of the catalytic converter 52 may not be essential in the present invention and may therefore be dispensed with.
Although the muffler of the present invention can be suitably applied to the carburetor type engine having no function of fuel cutting at the time the engine is halted, the muffler of the present invention can be equally applied to the carburetor type engine having the fuel cutting function or a combustion engine of a fuel injection system.
In addition, although the present invention has been shown and described as applied to the engine for use in the agricultural machine, the muffler of the present invention can be equally applied to the engine used in any passenger transporting vehicle other than the agricultural machine or to the engine of a ground installation type.
Accordingly, such changes and modifications are, unless they depart from the scope of the present invention as delivered from the claims annexed hereto, to be construed as included therein.
Number | Date | Country | Kind |
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2015-242579 | Dec 2015 | JP | national |
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2832430 | Coombs | Apr 1958 | A |
4147230 | Ormond | Apr 1979 | A |
4444288 | Sekiya | Apr 1984 | A |
5058704 | Yu | Oct 1991 | A |
5338903 | Winberg | Aug 1994 | A |
5738184 | Masuda | Apr 1998 | A |
20030121722 | Crombeen | Jul 2003 | A1 |
Number | Date | Country |
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201225189 | Apr 2009 | CN |
05098957 | Apr 1993 | JP |
09-228836 | Sep 1997 | JP |
09228836 | Sep 1997 | JP |
Number | Date | Country | |
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20170167333 A1 | Jun 2017 | US |