JP2006329068A - Exhaust muffler and exhaust temperature reduction component - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an exhaust muffler capable of effectively lowering exhaust gas temperature in a simpler way. <P>SOLUTION: This exhaust muffler 1 is provided with an exhaust passage 22 for emitting exhaust gas A from an exhaust port 18 to the atmosphere without sucking outside air. The exhaust passage 22 is provided with a throttle part 23 contracting a flow passage of the exhaust gas A and with an expansion part 24 extending from the throttle part 23 to the exhaust port 18 while smoothly expanding the flow passage of the exhaust gas A. When passing through the throttle part 23, the exhaust gas A is compressed once. Immediately after that, the exhaust gas A is guided to an inclined face of the expansion part 24 and expanded again, and then, is emitted from the exhaust port 18 and diffused to the atmosphere. Due to this, the temperature of the exhaust gas A emitted and diffused to the atmosphere can be effectively lowered, and exhaust noise can be also lowered. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an exhaust muffler for an internal combustion engine. The present invention also relates to an exhaust muffler tail pipe, and further relates to an exhaust temperature reducing component capable of reducing the temperature of the exhaust from the tail pipe by being attached to an existing exhaust muffler tail pipe.

The temperature of the exhaust gas released from the exhaust muffler of the internal combustion engine into the atmosphere is preferably as low as possible for work safety. As an exhaust muffler that can effectively reduce the temperature of exhaust gas, a venturi pipe having an outside air introduction hole is connected to the exhaust port, and the outside air is mixed into the exhaust gas and discharged into the atmosphere using the jet of the exhaust gas. What has been made is proposed (see Patent Document 1).
Japanese Patent No. 3499741

  The present invention intends to provide an exhaust muffler that can effectively reduce the temperature of exhaust gas by a simpler method different from the above-mentioned proposal.

  The present invention is also intended to provide a tail pipe suitable for use as a component of the exhaust muffler, and further, by attaching to a tail pipe for an existing exhaust muffler, exhaust gas from the tail pipe can be reduced. An object of the present invention is to provide an exhaust temperature reducing component capable of effectively reducing the temperature.

  In order to solve the above-described problems, an exhaust muffler according to the present invention includes an exhaust passage that discharges exhaust gas from an exhaust port to the atmosphere without inhaling outside air, and the exhaust passage is a throttle that reduces the exhaust gas passage. And an enlarged portion extending from the throttle portion to the exhaust port while smoothly expanding the flow path of the exhaust gas (Claim 1).

  According to the exhaust muffler, the exhaust gas is once compressed when it passes through the throttle portion, and immediately thereafter, is guided by the inclined surface of the enlarged portion and re-expanded, and is discharged from the exhaust port and diffused into the atmosphere. Is done. For this reason, the temperature of the exhaust gas released and diffused into the atmosphere is effectively lowered, and exhaust noise is also reduced. Further, by providing the throttle portion, an appropriate back pressure can be applied, so that unburned gas can be prevented from being blown out from the cylinder of the internal combustion engine, and air pollution due to exhaust emission can be reduced. Since the exhaust muffler discharges exhaust gas into the atmosphere without inhaling outside air, the exhaust muffler does not include an outside air introduction hole unlike the conventional proposal, and has a simpler configuration. Furthermore, since the pressure difference between the throttle part and the enlarged part becomes larger than when the outside air introduction hole is provided, it is possible to further contribute to the reduction of the exhaust gas temperature.

  An exhaust muffler tail pipe according to the present invention includes an exhaust port and an inner peripheral surface communicating with the exhaust port, and the exhaust muffler exhausts exhaust gas from the exhaust port to the atmosphere without sucking outside air. The tail pipe, the inner peripheral surface includes a throttle part that reduces a flow path of the exhaust gas, and an enlarged part that extends from the throttle part to the exhaust port while smoothly expanding the flow path of the exhaust gas. (Claim 2).

  The exhaust pipe muffler tail pipe can be easily provided with the same effects as described above only by being attached to a ready-made exhaust muffler.

  The exhaust temperature reducing component according to the present invention includes an inner peripheral surface that is continuous with the inner peripheral surface of the tail pipe without allowing the inflow of outside air in the attached state to the tail pipe for the exhaust muffler, and the inner peripheral surface is And a throttle part for reducing the flow path of the exhaust gas, and an enlarged part extending from the throttle part to the exhaust port while smoothly expanding the flow path of the exhaust gas.

  The exhaust temperature reducing component can easily provide the same effect as described above only by being attached to a ready-made exhaust muffler or a ready-made tail pipe.

  As a preferred embodiment of the exhaust temperature reducing component, an outer peripheral surface that fits in a press-fit manner may be provided on the inner peripheral surface of the outer end portion of the exhaust muffler tail pipe (Claim 4). In this case, the exhaust temperature reducing component can be attached by being press-fitted into the outer end portion of the tail pipe. In order to secure the attachment, another fixing method such as welding may be used after press-fitting. In this embodiment, since the exhaust temperature reducing component is located inside the tail pipe, the exhaust temperature reducing component is exhausted as compared with the case where the exhaust temperature reducing component is disposed so as to protrude from the outer end portion of the tail pipe. The overall shape of the muffler is compact. Therefore, for example, it is particularly suitable for an internal combustion engine of a portable or handheld power working machine.

  Hereinafter, an embodiment for carrying out the present invention will be described with reference to the accompanying drawings.

  FIG. 1 is a partially cutaway front view of an exhaust muffler according to an embodiment of the present invention, and FIG. 2 is a sectional view taken along the line II-II in FIG.

  As shown in FIG. 2, the exhaust muffler 1 according to the present embodiment is a schliere scavenging type small air-cooled two-pipe suitable for use as a power source of an internal combustion engine, particularly a portable power working machine such as a brush cutter or a chain saw. It is used by being attached to the cylinder 3 of the cycle gasoline engine 2. However, the present invention is not limited to this, and it goes without saying that the exhaust muffler of the present invention can be applied to general internal combustion engines.

  The exhaust muffler 1 includes a muffler body 4 and a tail pipe 5 that is detachably attached to the muffler body 4.

  The muffler body 4 has an appropriate configuration known per se, and is formed by, for example, a combination of two cup-shaped body cases 6 and 7 opened on one side, and has an expansion chamber 8 and an oxidation catalyst inside. And an exhaust gas purifying member (not shown). The one main body case 6 is formed with a combustion gas inlet 9 communicating with the expansion chamber 8, and the other main body case 7 is formed with an exhaust gas outlet 10 communicating with the expansion chamber 8. The muffler body 4 is provided with bolt insertion sleeves 13 and 14 that pass through the body cases 6 and 7. The muffler body 4 has the combustion gas inlet 9 aligned with the combustion gas outlet 11 of the cylinder 3 and a heat insulating plate 12 serving as a gasket interposed between the cylinder 3 and the bolt insertion sleeve 13. , 14 are inserted into the bolts 31 and 32, and the tip portions of the bolts 31 and 32 are screwed into female threads (not shown) of the cylinder 3 to be fixed to the cylinder 3.

  On the other hand, as shown in FIG. 1, the tail pipe 5 is integrally provided with a pipe main body 15 and a flange portion 16 serving as an attachment portion to the muffler main body 4. An exhaust gas inlet 17 is formed at the inner end 15a of the pipe body 15, and a final exhaust port 18 for releasing the exhaust gas into the atmosphere is formed at the outer end 15b of the pipe body 15. The tail pipe 5 is welded around the exhaust gas inlet 17 with the exhaust gas inlet 17 aligned with the exhaust gas outlet 10 after the exhaust gas outlet 10 of the muffler body 4 is fitted with a spark prevention mesh 19. The flange portion 16 fixed by an appropriate method such as the above is superposed on the mounting surface of the other body case 7, and screws 20, 20 inserted through screw insertion holes (not shown) of the flange portion 16 are attached to the other body case 7. By screwing into the nuts 21 and 21 fixed inside the main body case 7, the main body case 7 is airtightly fixed to the other main body case 7.

  The inner peripheral surfaces 5a and 25b of the tail pipe 5 define an exhaust passage 22 for the exhaust gas A, and the exhaust gas A from the muffler main body 4 passes through the exhaust passage 22 from the exhaust port 18 to the atmosphere. And released. Since the exhaust passage 22 is closed except for the exhaust gas inlet 17 and the exhaust port 18, the tail pipe 5 does not inhale any outside air, and the exhaust gas A is discharged only from the exhaust port 18 to the atmosphere. It will be discharged.

  The exhaust passage 22 includes a throttle part 23 that reduces the flow path of the exhaust gas A, and a tapered enlarged part 24 that extends from the throttle part 23 to the exhaust port 18 while smoothly expanding the flow path of the exhaust gas A. It is equipped with. The throttle portion 23 and the enlarged portion 24 can be formed integrally with the pipe body 15 when the pipe body 15 is formed. In the present embodiment, the exhaust temperature is reduced after the pipe body 15 is manufactured. By attaching a tubular part 25 as a reduction part to the pipe body 15, the throttle part 23 and the enlarged part 24 are additionally formed in the pipe body 15. In this way, the ready-made tail pipe 5 'can be used as it is, which is preferable. The cylindrical part 25 can be formed as an additional part using the same metal material, heat-resistant synthetic resin, or the like as the ready-made tail pipe 5 ′.

  The cylindrical part 25 includes a cylindrical outer peripheral surface 25a that fits into the inner peripheral surface 15c of the outer end portion 15b of the pipe body 15 in a press-fit manner. For this reason, it can be attached by being press-fitted into the ready-made tail pipe 5 ′ from the exhaust port 18. In order to secure the attachment, another fixing method such as welding may be used after press-fitting. In the present embodiment, the tubular part 25 is press-fitted and fixed until it entirely fits into the ready-made tail pipe 5 ′. Therefore, before and after the attachment of the tubular part 25, the exhaust There is no change in the overall shape of the muffler 1. Therefore, for example, it is particularly suitable for an internal combustion engine of a portable or handheld power working machine.

  In the attached state to the ready-made tail pipe 5 ′, the inner peripheral surface 25 b of the cylindrical part 25 is continuous with the inner peripheral surface 5 a of the ready-made tail pipe 5 ′. The inner peripheral surface 25b of the cylindrical part 25 includes the throttle portion 23 and the enlarged portion 24, and defines the exhaust passage 22 together with the inner peripheral surface 5a of the ready-made tail pipe 5 ′. . The throttle portion 23 is rounded and continues to the enlarged portion 24 so as not to hinder the smooth flow of the exhaust gas A as much as possible. The enlarged portion 24 extends in a tapered manner to the exhaust port 18 of the ready-made tail pipe 5 ′, and the outer edge 24a of the enlarged portion 24, that is, the outer edge of the cylindrical component 25 is It substantially coincides with the exhaust port 18.

  In the above-described configuration, the exhaust gas A from the muffler body 4 is released into the atmosphere through the tail pipe 5, and is compressed once when passing through the throttle portion 23 in the tail pipe 5, Immediately after that, it is re-expanded by being guided by the inclined surface of the enlarged portion 24, discharged from the exhaust port 18 and diffused into the atmosphere. For this reason, the temperature of the exhaust gas released and diffused into the atmosphere is effectively lowered, and exhaust noise is also reduced. In addition, since the throttle portion 23 is provided, an appropriate back pressure can be applied, so that unburned gas from the cylinder 3 can be prevented from being blown through, and air pollution due to exhaust emission can be reduced.

  The tubular part 25 of the present embodiment is a part that can be added to the inside of the ready-made tail pipe 5 ′. As an alternative exhaust gas temperature reducing part of another embodiment, for example, the ready-made tail pipe 5 ′ It is also possible to adopt an external addition type, such as one having an adaptive mounting portion on the outer peripheral surface of the tail pipe 5 ′. In this case, the external additional component includes an inner peripheral surface that is airtightly continuous with the inner peripheral surface 5a of the ready-made tail pipe 5 ′ in the state of being attached to the ready-made tail pipe 5 ′. The inner peripheral surface has a narrowed portion 23 and an enlarged portion 24, similarly to the internal additional component 25. In the case of this embodiment, the end opening of the external additional type part is the final exhaust port.

  In either case of internal addition type or external addition type, according to the exhaust temperature reduction component, the above-mentioned effect can be easily imparted by simply attaching it to a ready-made exhaust muffler or a ready-made tail pipe. It is.

1 is a partially cutaway front view of an exhaust muffler according to an embodiment of the present invention. It is II-II arrow sectional drawing of FIG.

Explanation of symbols

5 Exhaust muffler tail pipe 5 '(Pre-made) exhaust muffler tail pipe 5a Inner peripheral surface 15b Outer end of tail pipe 15c Inner peripheral surface 18 Exhaust port (final exhaust port)
22 Exhaust passage 23 Restricted portion 24 Enlarged portion 25a Outer peripheral surface 25b Inner peripheral surface A Exhaust gas

Claims (4)

  An exhaust passage (22) that discharges exhaust gas (A) from the exhaust port (18) to the atmosphere without sucking outside air is provided, and the exhaust passage (22) is a throttle that reduces the flow path of the exhaust gas (A). An exhaust muffler comprising: a portion (23); and an enlarged portion (24) extending from the throttle portion (23) to the exhaust port (18) while smoothly expanding the flow path of the exhaust gas (A).   An exhaust port (18) and inner peripheral surfaces (5a, 25b) communicating with the exhaust port (18) are provided, and the exhaust gas (A) is discharged from the exhaust port (18) into the atmosphere without sucking outside air. And the exhaust pipe muffler tail pipe (5), wherein the inner peripheral surface (5a) has a throttle part (23) for reducing the flow path of the exhaust gas (A) and the exhaust gas from the throttle part (23). An exhaust muffler tail pipe comprising: an enlarged portion (24) extending to the exhaust port (18) while smoothly expanding the flow path of (A).   An inner peripheral surface (25b) continuous with the inner peripheral surface (5a) of the tail pipe (5a) without allowing inflow of outside air in the attached state to the tail pipe (5 ') for the exhaust muffler, The inner peripheral surface (25b) has a throttle part (23) for reducing the flow path of the exhaust gas (A), and an exhaust port (18) while smoothly expanding the flow path of the exhaust gas (A) from the throttle part (23). And an enlarged portion (24) extending to the exhaust temperature reduction component.   The exhaust temperature reducing component according to claim 3, further comprising an outer peripheral surface (25a) that fits into an inner peripheral surface (15c) of an outer end portion (15b) of the tail pipe (5 ') for the exhaust muffler. .

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