JP4411463B2 - Small engine muffler - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a muffler suitable for use in a small engine used in, for example, a brush cutter or a chain saw.
[0002]
[Prior art]
As a conventional engine muffler, a muffler with improved silencing effect and a component designed to reduce harmful components in exhaust gas have been developed.
As shown in FIG. 6, a muffler used for a small engine designed to reduce harmful components in exhaust gas includes an exhaust gas first expansion chamber 2 having an exhaust gas inlet 1 connected to an exhaust port of the engine. And a second expansion chamber 4 having an exhaust gas outlet 3, and a honeycomb structure made of, for example, stainless steel having innumerable small holes along the axial direction between the first expansion chamber 2 and the second expansion chamber 4. The exhaust gas purifier 5 in which the catalyst for purifying the exhaust gas is coated on the substrate is provided.
[0003]
[Problems to be solved by the invention]
In the conventional small engine muffler as shown in FIG. 6, the exhaust gas of the engine enters the first expansion chamber 2 from the exhaust gas inlet 1, passes through the exhaust gas purifier 5 provided therein, and passes through the second expansion chamber. 4 and is discharged from the exhaust gas outlet 3 to the atmosphere. Accordingly, the muffler inner wall plate 2a of the first expansion chamber 2 and the muffler outer wall plate 4a of the second expansion chamber 4 are heated to about 700-800 ° C. with exhaust gas. Therefore, when this muffler is attached to the engine, In this case, a heat-insulating metal cover 7 is not provided at a position spaced from the muffler outer wall plate 4a, and a heat-resistant plastic muffler guard 8 is not disposed at a position spaced from the metal cover 7. As a result, there is a problem that the outer shape of the engine is increased accordingly, which is against the miniaturization of the engine.
[0004]
Further, when the muffler outer wall plate becomes red-hot by exhaust gas, if the plastic muffler guard 8 is burned out or the temperature of the exhaust gas discharged from the exhaust gas outlet 3 of the muffler to the atmosphere becomes high, for example, drying in the United States or the like If a brush cutter or a chainsaw using an engine equipped with such a muffler is placed on the ground in such a dry zone, the grass may catch fire and a fire may occur.
Also, in the prior art, a metal cover and a muffler guard were attached at a predetermined interval from the muffler outer wall plate so that the red-heated muffler outer wall plate could not be seen directly. However, it was not suitable for portable small engines due to the expansion of volume (enlargement).
Further, in the prior art, it has been impossible to reduce the temperature of high-temperature exhaust gas with a short exhaust gas diffusion distance in a compact small engine.
An object of the present invention is to provide a muffler for a small engine that solves such a conventional problem.
[0005]
[Means for Solving the Problems]
DETAILED DESCRIPTION OF THE INVENTION The present invention, which is a means for solving the above-mentioned problems, will be described with reference to the drawings. The invention according to claim 1 has a groove-like shape in a portion facing an exhaust gas inlet 11 connected to an exhaust port of an engine. A first partition plate 12 that defines the first expansion chamber 14 between the muffler inner wall plate 13 and the exhaust gas guiding portion 12a is provided. A hole 12c is formed, an exhaust gas flow small hole 12e is also formed in the lower portion 12d of the first partition plate 12, and a second portion extends from at least the central portion 12b of the first partition plate 12 to the outside of the lower portion 12d. A second partition plate 16 that defines the expansion chamber 15 is provided, and a muffler outer wall plate 17 that covers the second partition plate 16 and the upper portion 12 f of the first partition plate 12 is provided, and communicates with the second expansion chamber 15. The exhaust gas outlet 18 is provided. It is obtained by the muffler of small engine to be.
[0006]
The invention according to claim 2 is characterized in that the exhaust gas outlet 18 is provided in a direction orthogonal to the direction of the exhaust gas flow hole 12e formed in the lower portion 12d of the first partition plate 12. A small engine muffler according to claim 1.
[0007]
In the invention according to claim 3, the tail of the exhaust cylinder 19 provided so that the exhaust gas outlet 18 communicates with the exhaust gas flow hole 12e formed in the lower portion 12d of the first partition plate 12. 3. The small engine muffler according to claim 1 or 2, wherein a hole diameter and a number of holes are designed and drilled in the plate 19a so as to reach a minimum temperature while measuring the exhaust gas temperature. is there.
[0008]
The invention according to claim 4 is characterized in that a shape 20 is provided on the outer periphery of the exhaust gas outlet 18 so that the surrounding atmosphere is guided and ejected when the exhaust gas is ejected into the atmosphere. The small engine muffler according to any one of claims 1 to 3.
[0009]
The invention according to claim 5 is a muffler for a small engine according to any one of claims 1 to 4, wherein a wire mesh 21 is provided inside the exhaust gas outlet 18. It is.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of a muffler for a small engine according to the present invention will be described below in detail with reference to the drawings. 1A shows a cross-sectional view of the muffler, FIG. 1B shows an enlarged view of a portion C in FIG. 1A, and FIG. 1C shows an enlarged view of a portion D in FIG. It is. 2 shows a cross-sectional view taken along line AA in FIG. 1, and FIG. 3 shows a cross-sectional view taken along line BB in FIG. 4A shows a front view of the muffler, FIG. 4B shows a left side view, FIG. 4C shows an enlarged view of a portion E in FIG. 4A, and FIG. (A) shows the enlarged view of the F section in the figure.
[0011]
A muffler for a small engine according to claim 1 of the present invention is provided with a muffler inner side wall plate 13 having a groove-shaped exhaust gas guiding portion 12a formed in a portion facing an exhaust gas inlet 11 connected to an exhaust port of the engine. A first partition plate 12 that partitions the first expansion chamber 14 is provided. An exhaust gas circulation small hole 12 c is formed in the central portion 12 b of the first partition plate 12, and an exhaust gas circulation small hole 12 e is also formed in the lower portion 12 d of the first partition plate 12. A second partition plate 16 for partitioning and forming a second expansion chamber 15 is provided from at least the central portion 12b of the first partition plate 12 to the outside of the lower portion 12d. A muffler outer wall plate 17 that covers the second partition plate 16 and the upper portion 12f of the first partition plate 12 is provided. Further, an exhaust gas outlet 18 (see FIG. 4) communicating with the second expansion chamber 15 is provided.
[0012]
By configuring the muffler of the small engine according to claim 1 in this way, the exhaust gas entering from the exhaust gas inlet 11 is guided to the concave groove-shaped exhaust gas guiding portion 12a formed in the first partition plate 12. Then, it enters the first expansion chamber 14, enters the second expansion chamber 15 through the exhaust gas flow holes 12c and 12e drilled in the central portion 12b and the lower portion 12d of the first partition plate 12, and enters the second expansion chamber 15. It is discharged from the expansion chamber 15 through the exhaust gas outlet 18 to the atmosphere. As the exhaust gas passes through the first expansion chamber 14 and the second expansion chamber 15 in this way, a silencing action is obtained and the temperature of the exhaust gas is lowered. Also. The exhaust gas is guided to the concave groove-shaped exhaust gas guiding portion 12a formed in the first partition plate 12, and the exhaust gas flows smoothly into the first expansion chamber 14, so that the heating to the first partition plate 12 is reduced, In addition, since the second partition plate 16 that partitions the second expansion chamber 15 from at least the central portion 12b to the outside of the lower portion 12d of the first partition plate 12 is provided, the temperature of the muffler outer wall plate 17 is lowered. Can do.
[0013]
Further, the muffler of the small engine according to claim 2 of the present invention is a direction orthogonal to the direction of the exhaust gas flow hole 12e in which the exhaust gas outlet 18 is formed in the lower portion 12d of the first partition plate 12. The small engine muffler according to claim 1, wherein the muffler is provided in the small engine.
With this configuration, the exhaust gas that has entered the second expansion chamber 15 does not flow directly in the direction of the exhaust gas outlet 18 but stays in the second expansion chamber 15, so that the exhaust gas outlet 18 enters the atmosphere. The emitted exhaust noise and exhaust gas temperature can be lowered.
[0014]
Further, in the muffler of the small engine according to claim 3 of the present invention, the exhaust gas outlet 18 is provided so as to communicate with the exhaust gas circulation small hole 12e formed in the lower portion 12d of the first partition plate 12. The small engine according to claim 1 or 2, wherein the tail plate (19a) of the cylinder body (19) is provided with a hole diameter and a number that are designed so as to reach a minimum temperature while measuring the exhaust gas temperature. It is a muffler.
In this way, the exhaust gas outlet 18 is designed and drilled in the tail plate 19a of the exhaust cylinder 19 so that the exhaust gas temperature is the lowest while measuring the exhaust gas temperature. The temperature of the exhaust gas discharged from the atmosphere 18 can be lowered.
[0015]
Further, in the muffler of the small engine according to claim 4 of the present invention, the outer peripheral portion of the exhaust gas outlet 18 has a shape 20 that induces and injects the surrounding atmosphere when the exhaust gas is injected into the atmosphere. A muffler for a small engine according to any one of claims 1 to 3, wherein the muffler is a small engine.
With this configuration, when the exhaust gas is discharged from the exhaust gas outlet 18 to the atmosphere, the shape 20 that induces and ejects the atmosphere around the exhaust gas outlet 18, the surroundings of the exhaust gas outlet 18 Since the atmosphere is guided and released, the exhaust gas and the atmosphere are mixed, and the temperature of the exhaust gas discharged from the exhaust gas outlet can be lowered.
[0016]
The small engine muffler according to claim 5 of the present invention is characterized in that a metal mesh 21 is provided inside the exhaust gas outlet 18. It is an engine muffler.
With this configuration, the exhaust gas flowing from the second expansion chamber 15 to the exhaust gas outlet 18 flows while being resisted by the wire mesh 21, thus preventing discharge of sparks and releasing from the exhaust gas outlet 18 to the atmosphere. The exhaust gas speed can be reduced and the temperature can be lowered.
[0017]
In addition, the code | symbol (number) 22 shown in FIG. 1 and FIG. 2 is a wall board provided inside the said muffler inner side wall board 13, and the heating temperature to the muffler inner side wall board 13 can be lowered | hung by this. 2 is a muffler mounting hole. 4 (d) shows an enlarged view of the portion F in FIG. 4 (a). In the partition plate 9 between the second expansion chamber 15 and the wire mesh 21, an exhaust gas circulation small hole is shown. 10 is drilled so as not to face the exhaust gas outlet 18 drilled in the tail plate 19a.
[0018]
FIG. 5 is a cross-sectional view of a small engine equipped with a muffler M according to the present invention. Reference numeral 24 denotes a piston disposed in a reciprocating manner in a cylinder 25, and 24 'denotes a lowered piston. Yes. The piston 24 is connected to a crankpin 29 of a crankshaft 28 via a piston pin 26 and a connecting rod 27. An intake valve 31 and an exhaust valve 32 are disposed on the ceiling of the combustion chamber 30 in the cylinder 25, and the intake valve 31 is pushed down by the rocker arm 34 against the valve spring 33 in the intake process to open the valve. The exhaust valve 32 is pushed down by the rocker arm 36 against the valve spring 35 in the exhaust process to open. The exhaust valve 32 communicates with an exhaust port (exhaust port) 37, and the exhaust port 37 is connected to the exhaust gas inlet 11 of the muffler M.
[0019]
A mixed gas inflow port 40 from the carburetor 38 through the reed valve 39 is formed in the wall surface of the cylinder 25, and when the piston 24 moves up, the mixed gas flows into the cylinder 25 from the inflow port 40. When the piston 24 is lowered, the mixed gas is pressed into the crank chamber 41 and passes through a reed valve (not shown) provided in the crank chamber 41a defined by the crankcase 41 and interlocks with the cam gear. The intake valve 31 is opened through a push rod chamber in which a cam, a cam lifter and a push rod (not shown) for driving the rocker arms 34 and 36 are disposed, and a rocker arm chamber 42 in which a rocker arm is disposed. At that time, it is sucked into the combustion chamber 30. As described above, when the mixed gas flows, the oil contained in the mixed gas adheres to each sliding portion, rotating portion, and rotating portion and performs a lubricating action.
[0020]
5 is an air cleaner provided with a filter 43a, 44 is a fuel tank, 45 is a fuel pipe having a weighted filter 46 at its tip, and its tip is connected to the carburetor 38. In addition, although this muffler demonstrated embodiment attached to the 4-cycle engine, it can also be attached to a 2-cycle engine (not shown).
[0021]
【The invention's effect】
Since the muffler of the small engine according to the first aspect of the present invention is configured as described above, the noise reduction effect is obtained by the exhaust gas entering from the exhaust gas inlet passing through the first expansion chamber and the second expansion chamber. And the temperature of the exhaust gas decreases. Also. Since the exhaust gas is smoothly guided to the first expansion chamber by being guided by the groove-shaped exhaust gas guiding portion formed in the first partition plate, the heating of the first partition plate is reduced, and the first partition plate Since the second partition plate for partitioning the second expansion chamber is provided from at least the center of the partition plate to the outside of the lower portion, the temperature of the muffler outer wall plate can be lowered.
[0022]
In addition, since the muffler of the small engine according to claim 2 of the present invention is configured as described above, the exhaust gas that has entered the second expansion chamber does not flow directly in the direction of the exhaust gas outlet. Since it stays in the expansion chamber, it is possible to lower the exhaust sound and the exhaust gas temperature released from the exhaust gas outlet to the atmosphere.
[0023]
In addition, since the muffler of the small engine according to claim 3 of the present invention is configured as described above, the exhaust gas outlet is provided at the tail plate of the exhaust cylinder so that the exhaust gas temperature is measured while the exhaust gas temperature is measured. By designing and drilling with a proper hole diameter and number, the exhaust gas is discharged from the exhaust gas outlet to the atmosphere in a wide range, and the temperature of the exhaust gas can be lowered.
[0024]
Further, since the muffler of the small engine according to claim 4 of the present invention is configured as described above, when the exhaust gas is discharged from the exhaust gas outlet to the atmosphere, the atmosphere around the exhaust gas outlet is guided and ejected. With such a shape, the atmosphere around the exhaust gas outlet is guided and released, so that the exhaust gas and the atmosphere are mixed and the temperature of the exhaust gas discharged from the exhaust gas outlet can be lowered.
[0025]
Further, since the muffler of the small engine according to claim 5 of the present invention is configured as described above, the exhaust gas flowing from the second expansion chamber to the exhaust gas outlet flows while being resisted by the wire mesh. Can be prevented, the speed of the exhaust gas discharged from the exhaust gas outlet to the atmosphere can be reduced, and the temperature can be lowered.
[Brief description of the drawings]
1A is a cross-sectional view of the muffler, FIG. 1B is an enlarged view of a portion C in FIG. 1A, and FIG. 1C is an enlarged view of a portion D in FIG. .
FIG. 2 is a sectional view taken along line AA in FIG.
FIG. 3 is a sectional view taken along line BB in FIG.
4 (a) is a front view of the muffler, FIG. 4 (b) is a left side view, FIG. 4 (c) is an enlarged view of portion E in FIG. 4 (a), and FIG. It is an enlarged view of the F section in the figure.
FIG. 5 is a sectional view of a small engine provided with a muffler M according to the present invention.
FIG. 6 is a sectional view of a muffler of a conventional small engine.
[Explanation of symbols]
9 Partition plate 10 Exhaust gas circulation small hole 11 Exhaust gas inlet 12 First partition plate 12a Exhaust gas guiding part 12b Central part 12c Exhaust gas circulation small hole 12d Lower part 12e Exhaust gas circulation small hole 12f Upper part 13 Muffler inner side wall plate 14 First expansion chamber 15 Second expansion chamber 16 Second partition plate 17 Muffler outer wall plate 18 Exhaust gas outlet 19 Exhaust cylinder 19a Tail plate 20 Shape 21 that guides and blows out the atmosphere around the exhaust gas outlet 21 Wire mesh 22 Wall plate 23 Muffler mounting hole 24 Piston 25 Cylinder 26 Piston pin 27 Connecting rod 28 Crank shaft 29 Crank pin 30 Combustion chamber 31 Intake valve 32 Exhaust valve 33 Valve spring 34 Rocker arm 35 Valve spring 36 Rocker arm 37 Exhaust port (exhaust port)
38 Carburetor 39 Reed Valve 40 Mixed Gas Inlet 41 Crank Case 41a Crank Chamber 42 Rocker Arm Chamber 43 Air Cleaner 43a Filter 44 Fuel Tank 45 Fuel Pipe 46 Weighted Filter

Claims (5)

Provided with a first partition plate that forms a first expansion chamber with an inner wall plate of the muffler, in which a concave groove-like exhaust gas guiding portion is formed in a portion facing the exhaust gas inlet connected to the exhaust port of the engine, An exhaust gas flow hole is drilled in the center of the first partition plate, and an exhaust gas flow hole is drilled in the lower part of the first partition plate. A second partition plate that partitions and forms the second expansion chamber is provided on the outside of the section, and a muffler outer wall plate that covers an upper portion of the second partition plate and the first partition plate is provided, and the exhaust communicated with the second expansion chamber A small engine muffler characterized by a gas outlet. 2. The muffler for a small engine according to claim 1, wherein the exhaust gas outlet is provided in a direction orthogonal to a direction of an exhaust gas flow hole formed in a lower portion of the first partition plate. The exhaust gas outlet is adjusted to the lowest temperature while measuring the exhaust gas temperature on the tail plate of the exhaust cylinder provided so as to communicate with the exhaust gas flow hole formed in the lower part of the first partition plate. The muffler for a small engine according to claim 1 or 2, wherein a small hole diameter and number are designed and drilled. 4. The shape according to claim 1, wherein an outer peripheral portion of the exhaust gas outlet is shaped so as to guide and eject the surrounding atmosphere when the exhaust gas is ejected to the atmosphere. 5. A small engine muffler. The muffler for a small engine according to any one of claims 1 to 4, wherein a metal mesh is provided inside the exhaust gas outlet.

Images