JP2017198112A - Engine muffler - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve an effect of noise reduction at a muffler.SOLUTION: A muffler 50 comprises a box-shaped housing 51 having an inlet port 52a to which exhaust gas flows and a discharging port 53a for discharging exhaust gas; and a partition plate 56 for defining an inside of the housing 51 into a first chamber 61 including the inlet port 52a and a second chamber 62 including the discharging port 53a. The partition plate 56 includes a flat plate-shaped body part 56a and a recess part 56b protruded toward the second chamber 62. The body part 56a has at its one side an open hole 57 communicating between the first chamber 61 and the second chamber 62. The recess part 56b has an area 56t3 of its bottom part 56bt abutted against an inner surface of the second chamber 62 at the housing 51. The exhaust gas flowing from the inlet port 52a into the first chamber 61 and reached one side in the inside of the second chamber 62 through the open hole 57 flows around a second recess portion 56b2 of the recess part 56b in the second chamber 62 and reaches the discharging port 53a through the other side inside the second chamber 62.SELECTED DRAWING: Figure 9

Description

  The present invention relates to an engine muffler.

An engine muffler mounted on a portable work machine such as a brush cutter is, for example, a box-shaped housing that has an inlet connected to an exhaust port of an engine and into which exhaust gas flows in, and an exhaust port through which the exhaust gas exhausted is discharged. Is provided. The inside of the housing is partitioned by a partition plate into a first chamber including the inflow port and a second chamber including the discharge port. The partition plate has a plurality of through holes that communicate the first chamber and the second chamber.
Such an engine muffler is disclosed in Patent Document 1.

JP 2014-181580 A

However, in the muffler disclosed in Patent Document 1, the substantial flow distance (movement distance) of the exhaust gas from the through hole of the partition plate to the discharge port of the housing is relatively short. Therefore, it is difficult to efficiently reduce the pressure of the exhaust gas in the second chamber, and as a result, it is difficult to sufficiently obtain the muffler noise reduction effect.
In view of such a situation, the present invention aims to improve the noise reduction effect of a muffler.

  Therefore, the engine muffler according to the first aspect of the present invention includes a box-shaped housing that is connected to an exhaust port of the engine and into which exhaust gas flows in, an exhaust port through which the exhaust gas flows in, and the housing. A partition plate partitioned into a first chamber including the inflow port and a second chamber including the discharge port. A partition plate contains the main-body part which is flat form, and the recessed part which protrudes in the 2nd chamber side from this main-body part. The main body has at least one through-hole communicating with the first chamber and the second chamber on one side thereof. At least a part of the bottom of the concave portion is in contact with the inner surface of the second chamber in the housing. Exhaust gas flowing into the first chamber from the inlet and passing through the through hole to one side of the second chamber flows so as to go around the concave portion in the second chamber and pass through the other side of the second chamber. It reaches the discharge port.

  An engine muffler according to a second aspect of the present invention includes a box-shaped housing having an inlet connected to an exhaust port of an engine and into which exhaust gas flows in, and an exhaust port through which the exhaust gas discharged is discharged. A partition plate that divides into a first chamber including an inflow port and a second chamber including the discharge port; and a flow restricting portion that partially restricts a flow of exhaust gas in the second chamber. The partition plate has at least one through-hole communicating with the first chamber and the second chamber on one side thereof. The exhaust gas flowing into the first chamber from the inlet and passing through the through hole to one side of the second chamber flows so as to go around the flow restricting portion in the second chamber, and flows through the other side of the second chamber. After that, it reaches the outlet.

  According to the first aspect of the present invention, at least a part of the bottom of the concave portion of the partition plate is in contact with the inner surface of the second chamber in the housing. Further, the exhaust gas flowing into the first chamber from the inlet of the housing and passing through the through hole of the partition plate to one side of the second chamber flows so as to go around the concave portion of the partition plate in the second chamber. It reaches the outlet of the housing through the other side of the second chamber. Thereby, since the substantial flow distance (movement distance) of the exhaust gas from the through hole of the partition plate to the discharge port of the housing can be made relatively long, the pressure of the exhaust gas can be efficiently reduced in the second chamber. As a result, the muffler noise reduction effect can be improved.

  According to the second aspect of the present invention, the flow restricting part partially restricts the flow of the exhaust gas in the second chamber. Further, the exhaust gas flowing into the first chamber from the inlet of the housing and reaching one side of the second chamber through the through hole of the partition plate flows in the second chamber so as to circulate around the flow regulating portion. It reaches the outlet of the housing through the other side of the room. Thereby, since the substantial flow distance (movement distance) of the exhaust gas from the through hole of the partition plate to the discharge port of the housing can be made relatively long, the pressure of the exhaust gas can be efficiently reduced in the second chamber. As a result, the muffler noise reduction effect can be improved.

The perspective view of the brush cutter in one Embodiment of this invention Explanatory drawing of the usage state of the brush cutter in the same embodiment Sectional drawing which shows schematic structure of the engine and muffler in embodiment same as the above Front view of muffler in the same embodiment II sectional view of FIG. II-II sectional view of FIG. Front view of the partition plate in the same embodiment The figure which shows the flow of the waste gas in the muffler in embodiment same as the above The figure which shows the flow of the waste gas in the muffler in embodiment same as the above

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a perspective view of a brush cutter according to an embodiment of the present invention. FIG. 2 is an explanatory diagram of the usage state of the brush cutter. In the present embodiment, a brush cutter will be described as an example of a portable working machine on which the engine muffler according to the present invention is mounted. However, the portable working machine on which the engine muffler according to the present invention is mounted. Is not limited to this.

  The brush cutter 1 has an operation rod 2 made of a long pipe. An engine module 3 as a power source is provided at the rear end of the operation rod 2. A tool mounting portion 4 as a working portion is provided at the tip of the operation rod 2. A tool is replaceably attached to the tool mounting portion 4. The tool mounting portion 4 is connected to the engine module 3 by a drive shaft built in the operation rod 2. The tool mounting portion 4 is rotationally driven by the engine module 3 (specifically, the engine 21).

  A handle 5 is attached to the center of the operating rod 2 in the longitudinal direction. An anti-vibration housing 6 is provided between the handle 5 and the engine module 3. A hanger 7 is attached to the outer periphery of the vibration-proof housing 6.

  The brush cutter 1 is used by being hung from the shoulder of the worker M by the hanger 8. The hanger 8 has a harness 9 and a metal fitting 10. The worker M wears the harness 9 on the upper body. In FIG. 2, the metal fitting 10 hangs down on the right side of the worker M. The worker M attaches the hanger 7 to the metal fitting 10 and uses the brush cutter 1 in this suspended state. The worker M can hold the handle 5 of the brush cutter 1 with both hands and move the brush cutter 1 to perform the brush cutting work.

  The engine module 3 mainly includes a cover 11 that forms an outer shell thereof, an engine 21 (see FIG. 3 described later), and a muffler 50 that are covered by the cover 11. The muffler 50 corresponds to the “engine muffler” of the present invention. The cover 11 is made of, for example, resin.

  FIG. 3 is a cross-sectional view showing a schematic configuration of the engine 21 and the muffler 50. Here, FIG. 3 shows the engine 21 when the piston 25 is located near the top dead center. In the present embodiment, the upper side substantially coincides with the vertical upper side in the state where the engine 21 is used for the longest time (upright state).

  The engine 21 is an OHV (Over Head Valve) type four-stroke engine and is air-cooled. The engine 21 includes a cylinder part 22, a crankcase 23 attached to the lower part of the cylinder part 22, and an oil tank 24 provided below the crankcase 23.

The cylinder part 22 has a cylindrical space for sliding the piston 25 in the vertical direction in FIG. In this space, the piston 25 is fitted with a gap slidable in the vertical direction in FIG.
A crank chamber 27 is formed by the cylinder portion 22, the crankcase 23 and the piston 25. That is, the crank chamber 27 is formed by the side surface of the cylinder portion 22 and the cylindrical space on the crankcase 23 side formed by the piston 25 and the space in the crankcase 23. In the crank chamber 27, the volume of the internal space changes as the piston 25 slides.

A combustion chamber 29 is formed by the cylinder head 28, the cylinder portion 22, and the piston 25.
The oil tank 24 is defined by an oil tank case, is provided separately from the crankcase 23, and stores lubricating oil.

A check valve 30 is provided between the oil tank 24 and the crankcase 23 to allow only the oil flow from the crankcase 23 (crank chamber 27) to the oil tank 24.
Here, as the piston 25 moves from the bottom dead center to the top dead center, the pressure in the crank chamber 27 becomes negative. Conversely, as the piston 25 moves from top dead center to bottom dead center, the pressure in the crank chamber 27 becomes positive. Therefore, when the pressure in the crank chamber 27 is positive, the check valve 30 is opened and oil flows from the crank chamber 27 to the oil tank 24. When the pressure in the crank chamber 27 is negative, the check valve 30 is closed.

  A crank 33 is rotatably supported in the crankcase 23. The crank 33 includes a crankshaft 33a serving as a rotation center, a counterweight, and the like. The piston 25 and the crank 33 are connected by a connecting rod 34. The connecting rod 34 and the piston 25 are swingably connected. The connecting rod 34 and the crank 33 are rotatably connected. With such a configuration, the piston 25 reciprocates in the cylinder portion 22.

A cylinder head 28 is provided on the upper wall of the cylinder portion 22. The cylinder head 28 is provided with an intake port 35 and an exhaust port 36.
The intake port 35 communicates with a carburetor (not shown) via an insulator (not shown). An air cleaner (not shown) is provided on the upstream side of the carburetor. Here, the engine module 3 further includes the above-described insulator, carburetor, air cleaner, and fuel storage tank (not shown). Further, the above-described insulator, carburetor, and air cleaner are covered with a cover 11. The carburetor described above is a device that generates an air-fuel mixture by mixing fuel with the air that has passed through the air cleaner.

  The muffler 50 is formed in a vertically long and thin shape that is vertically long. In the present embodiment, the muffler 50 is directly connected to the exhaust port 36 of the engine 21 and communicates with each other. Details of the muffler 50 will be described later with reference to FIGS.

  The cylinder head 28 is provided with an intake valve 37 that opens and closes the intake port 35. The cylinder head 28 is provided with an exhaust valve 38 that opens and closes the exhaust port 36. Here, the intake valve 37 and the exhaust valve 38 open and close the combustion chamber 29.

Next, details of the muffler 50 will be described with reference to FIGS. 4 to 7 in addition to FIG. 3 described above.
FIG. 4 is a front view of the muffler 50. 5 is a cross-sectional view taken along the line II of FIG. 6 is a cross-sectional view taken along the line II-II in FIG. FIG. 7 is a front view of the partition plate 56. In the following, for convenience of explanation, as shown in FIGS. Further, the side close to the engine 21 is the inflow side, and the side opposite to the side close to the engine 21 (in other words, the side far from the engine 21) is the discharge side. Here, the “upper side” in FIGS. 4 to 7 substantially coincides with the vertical upper side in the state where the engine 21 is used for the longest (upright state) as described above. 4 to 7 correspond to “one side” and “one side in the lateral direction” of the present invention, while “right side” corresponds to “the other side” and “the other side in the lateral direction” of the present invention. Correspond.

The muffler 50 includes a housing 51, a partition plate 56, and a guide member 58.
The housing 51 has a substantially rectangular box shape, and includes a first container 52 and a second container 53. In the present embodiment, the first container 52 and the second container 53 are made of metal, but may be made of resin such as FRP (Fiber Reinforced Plastics) that can withstand high heat.

The first container 52 constitutes the inflow side of the housing 51. The first container 52 has a substantially rectangular box shape opened on the discharge side. The first container 52 has an outer flange portion 54 that protrudes outward at the peripheral portion on the discharge side.
An inflow port 52 a is provided in the upper part of the first container 52. The inflow port 52 a is connected to the exhaust port 36. Here, since the inflow port 52 a is provided in the upper part of the first container 52, the protruding amount of the muffler 50 above the engine 21 can be reduced.

The second container 53 constitutes the discharge side of the housing 51. The 2nd container 53 is a substantially rectangular box shape opened on the inflow side. The second container 53 has an outer flange portion 55 that protrudes outward at the peripheral edge portion on the inflow side thereof.
A convex portion 53p is formed slightly below the central portion in the vertical direction of the second container 53 so as to protrude outward (on the side opposite to the second chamber 62). As shown in FIG. 4, the convex portion 53p has a horizontally long rectangular shape when viewed from the front. The convex portion 53p has a substantially U-shaped cross-sectional shape and extends in the horizontal direction (left-right direction). An opening 53q is formed at the left end of the convex portion 53p. Here, a substantially rectangular opening portion at the inflow side end portion of the convex portion 53p (in other words, a substantially rectangular opening portion at the base end side end portion of the convex portion 53p) corresponds to the discharge port 53a. Accordingly, the convex portion 53p protrudes outward so as to cover the discharge port 53a, and has an opening 53q.

The partition plate 56 made of metal or resin is constituted by a main body portion 56a which is a substantially rectangular flat plate shape, and a concave portion 56b formed in the center portion in the lateral direction (left-right direction).
The peripheral portion of the main body portion 56 a of the partition plate 56 is sandwiched between the outer flange portion 54 of the first container 52 and the outer flange portion 55 of the second container 53. The container 53 is fixed by caulking. Accordingly, in the housing 51, the first chamber 61 is partitioned by the first container 52 and the partition plate 56, and the second chamber 62 is partitioned by the second container 53 and the partition plate 56. Here, the first chamber 61 includes an inflow port 52a. On the other hand, the second chamber 62 includes a discharge port 53a. The first chamber 61 communicates with the exhaust port 36 via the inflow port 52a.

The concave portion 56b of the partition plate 56 includes a first concave portion 56b1 that forms the upper portion thereof, and a second concave portion 56b2 that forms the central portion and the lower portion in the vertical direction.
The first concave portion 56b1 is opposed to the inlet 52a of the first container 52 with the guide member 58 therebetween. In other words, with the guide member 58 positioned between the first concave portion 56b1 and the inlet 52a of the first container 52, the first concave portion 56b1 and the inlet 52a of the first container 52 Are facing each other.

  The first concave portion 56b1 is curved in an arc so as to go downward from the inflow port 52a side toward the discharge side (that is, from the inflow side toward the discharge side). Here, the first concave portion 56b1 has a function of receiving the exhaust gas flowing into the first chamber 61 from the inflow port 52a and guiding it downward (for example, to the second concave portion 56b2).

The lower end portion of the first concave portion 56b1 is continuous with the upper end portion of the second concave portion 56b2. The second concave portion 56b2 protrudes more toward the discharge side than the first concave portion 56b1.
As shown in FIG. 7, the second concave portion 56b2 is substantially rectangular when viewed from the front, and the second container 53 is at least part of the bottom portion 56bt (see, for example, the portion P shown in FIG. 6). It is in contact with the inner surface. That is, at least a part of the bottom portion 56 bt of the concave portion 56 b is in contact with the inner surface of the second chamber 62 in the housing 51. Here, the bottom portion 56bt is a portion that forms an end wall on the discharge side in the second concave portion 56b2 of the concave portion 56b.

  A bottom portion 56bt of the second concave portion 56b2 has an exhaust gas passage forming portion 56bt1 that slightly protrudes toward the discharge side. The exhaust gas passage forming part 56bt1 closes a part of the exhaust port 53a (at least the left half in the present embodiment). Here, a portion of the discharge port 53a that is not blocked by the exhaust gas passage forming portion 56bt1 is a substantial opening portion 53a1 of the discharge port 53a. Further, the exhaust gas passage forming portion 56bt1 corresponds to “a portion of the bottom surface of the concave portion blocking a part of the discharge port”.

  An exhaust gas guide portion 56bt2 is formed in the second concave portion 56b2 so as to be adjacent to the right side of the exhaust gas passage forming portion 56bt1. As shown in FIG. 7, the exhaust gas guide portion 56bt2 is formed in a groove shape that is recessed toward the first chamber 61 when viewed from the front. The exhaust gas guide part 56bt2 has a function of guiding the exhaust gas in the second chamber 62 to the substantial opening 53a1 of the discharge port 53a.

As shown in FIG. 7, a plurality (10 in FIG. 7) of through holes 57 are formed on the left side portion of the main body portion 56 a of the partition plate 56. Here, the through hole 57 is positioned lower than the inflow port 52 a of the first container 52. 7 shows ten through holes 57, the number of through holes 57 is not limited to this.
In the present embodiment, as shown in FIG. 6, in the lateral direction (left-right direction), a concave portion 56b is formed between the discharge port 53a (particularly, the substantial opening 53a1) and the plurality of through holes 57. (In particular, the second concave portion 56b2) is located. Here, in the present embodiment, as shown in FIG. 7, a C-shape that spreads to surround the upper side, the lower side, and the left side of the exhaust gas passage forming portion 56 bt 1 among the bottom portion 56 bt of the second concave portion 56 b 2 of the concave portion 56 b. The region 56 bt 3 is in contact with the inner surface of the second chamber 62 in the housing 51.

  A tubular exhaust gas passage 67 having a substantially rectangular cross-sectional shape is formed by the convex portion 53p of the second container 53 and the exhaust gas passage formation portion 56bt1 of the second concave portion 56b2 of the partition plate 56. The exhaust gas passage 67 extends in the lateral direction (left-right direction), and communicates with the second chamber 62 via the discharge port 53a (particularly, the substantial opening portion 53a1) at the right side portion thereof. Further, the left end portion of the exhaust gas passage 67 corresponds to the aforementioned opening 53q. The exhaust gas passage 67 guides exhaust gas from the discharge port 53a (particularly, the substantial opening 53a1) to the opening 53q.

  At least one (two in FIGS. 4 and 6) cylindrical portion 65 is formed through the housing 51. The cylindrical portion 65 is formed so as to penetrate each of the first container 52, the second container 53, and the partition plate 56, and the cylindrical portion 65 includes a bolt that fixes the housing 51 to the engine 21. (Not shown) can be inserted. 4 and 6 show two cylindrical portions 65, the number of the cylindrical portions 65 is not limited to this. 7 shows a through hole 65a into which the cylindrical portion 65 is inserted.

  The guide member 58 is made of metal or resin, and is attached to the inlet 52 a of the first container 52. The guide member 58 has a U-shaped cross-sectional shape with an open bottom surface, and extends from the inflow port 52a of the first container 52 toward the discharge side. The guide member 58 has a function of smoothly guiding the exhaust gas flowing into the first chamber 61 from the exhaust port 36 through the inflow port 52 a to the concave portion 56 b of the partition plate 56.

  In the present embodiment, the concave portion 56 b (particularly, the second concave portion 56 b 2) of the partition plate 56 functions as the flow restricting portion 70 to partially restrict the flow of exhaust gas in the second chamber 62. Here, the flow restricting portion 70 restricts the linear flow of the exhaust gas from the through hole 57 toward the discharge port 53a (particularly, the substantial opening portion 53a1) in the lateral direction, particularly in the second chamber 62. doing. Moreover, in this embodiment, the flow control part 70 is a part (concave part 56b (especially 2nd concave part 56b2)) of the partition plate 56. FIG. In addition, the flow restricting portion 70 is interposed in the second chamber 62 between the housing 51 (particularly, the second container 53) and the partition plate 56 (particularly, the main body portion 56a).

  In the present embodiment, as shown in FIG. 5, the flow direction F1 of the exhaust gas at the inlet 52a of the first container 52 and the extending direction F2 from the lower end to the upper end of the main body portion 56a of the partition plate 56 have an obtuse angle θ1. A partition plate 56 is provided in the housing 51 so as to make it. This obtuse angle θ1 is preferably in the range of 95 ° to 125 °, more preferably in the range of 100 ° to 120 °.

  In the present embodiment, the distance L1 between the portion of the inner wall of the lower end portion of the first chamber 61 that faces the lower end portion of the main body portion 56a of the partition plate 56 and the lower end portion of the main body portion 56a of the partition plate 56 is The distance between the inner wall of the lower end portion of the two chambers 62 that faces the lower end portion of the main body portion 56a of the partition plate 56 and the distance L2 between the lower end portion of the main body portion 56a of the partition plate 56 is longer. In addition, the partition plate 56 has a concave portion 56b. As a result, a sufficient volume of the first chamber 61 into which high-temperature and high-pressure exhaust gas can flow can be ensured.

Next, the flow of exhaust gas discharged from the exhaust port 36 through the muffler 50 will be described.
8 and 9 are diagrams illustrating the flow of the exhaust gas in the muffler 50 according to the present embodiment. 8A corresponds to FIG. 5 described above, FIG. 9A corresponds to FIG. 6 described above, and FIG. 8B and FIG. 9B correspond to those described above. This corresponds to FIG.

  The exhaust gas flowing into the first chamber 61 from the exhaust port 36 through the inlet 52a of the muffler 50 is directed downward by the concave portion 56b (particularly, the first concave portion 56b1) of the partition plate 56. (Refer to the flow S1 of the exhaust gas indicated by the arrows in FIGS. 8A and 8B). Here, the concave portion 56b (particularly, the first concave portion 56b1) of the partition plate 56 realizes a function of receiving and guiding the exhaust gas flowing into the first chamber 61 from the inflow port 52a.

The exhaust gas is diffused and cooled in the first chamber 61, and then flows into the left side portion of the second chamber 62 through the through hole 57 of the partition plate 56 (FIGS. 8A and 8B). And the exhaust gas flow S2 indicated by an arrow in FIG. 9A).
The exhaust gas that has flowed into the left portion of the second chamber 62 flows in the second chamber 62 so as to wrap around above and below the concave portion 56b (particularly, the second concave portion 56b2) of the partition plate 56. It reaches the right side portion in the two chambers 62 (see exhaust gas flows S3 and S4 indicated by arrows in FIGS. 9A and 9B). The exhaust gas can also be diffused and cooled in the second chamber 62.

Thereafter, the exhaust gas passes through the exhaust gas guide portion 56bt2 of the partition plate 56 and the discharge port 53a (particularly, the substantial opening portion 53a1), passes through the exhaust gas passage 67, and passes through the opening 53q of the exhaust gas passage 67 to the outside. It is discharged (see exhaust gas flow S5 indicated by arrows in FIGS. 9A and 9B).
The first container 52, the second container 53, and the partition plate 56 receive heat from the exhaust gas passing through the muffler 50, and the heat is received from the outer surface of the first container 52 and the second container 53. Dissipate heat from the outer surface of the outside.

  According to the present embodiment, the muffler 50 includes a box-shaped housing 51 that is connected to the exhaust port 36 of the engine 21 and has an inflow port 52a through which exhaust gas flows and an exhaust port 53a through which the inflowing exhaust gas is discharged. A partition plate 56 that divides the inside 51 into a first chamber 61 including an inflow port 52a and a second chamber 62 including a discharge port 53a is included. The partition plate 56 includes a main body portion 56a having a flat plate shape and a concave portion 56b protruding from the main body portion 56a to the second chamber 62 side. The main body 56 a has at least one through hole 57 that communicates the first chamber 61 and the second chamber 62 on one side (left side) thereof. The concave portion 56 b is in contact with the inner surface of the second chamber 62 in the housing 51, at least a part of the bottom portion 56 bt (for example, the region 56 bt 3). The exhaust gas flowing into the first chamber 61 from the inlet 52a and passing through the through hole 57 to one side (left side) of the second chamber 62 is formed in the concave portion 56b (particularly, the second portion 62b). 2, and flows through the other side (right side) of the second chamber 62 to the discharge port 53a (particularly, the substantial opening portion 53a1) (the exhaust gas shown in FIGS. 8 and 9). (See streams S1-S5). Thereby, since the substantial flow distance (movement distance) of the exhaust gas from the through hole 57 of the partition plate 56 to the discharge port 53a of the housing 51 can be made relatively long, the pressure of the exhaust gas in the second chamber 62 Can be reduced efficiently, and as a result, the noise reduction effect of the muffler can be improved.

  Further, according to the present embodiment, the concave portion 56b (particularly, the second concave portion 56b2) is positioned between the discharge port 53a (particularly, the substantial opening portion 53a1) and the through hole 57. Thereby, with a simple configuration, the substantial flow distance (movement distance) of the exhaust gas from the through hole 57 of the partition plate 56 to the discharge port 53a of the housing 51 can be made relatively long.

  Further, according to the present embodiment, the concave portion 56b (particularly, the first concave portion 56b1) faces the inflow port 52a. Thereby, the exhaust gas flowing into the first chamber 61 from the inflow port 52a can be smoothly received by the concave portion 56b (particularly, the first concave portion 56b1).

  Further, according to the present embodiment, the inflow port 52 a is located in the upper part of the first chamber 61. The concave portion 56b receives the exhaust gas flowing into the first chamber 61 from the inflow port 52a and guides it downward. Thereby, the exhaust gas can be diffused well in the first chamber 61 and cooled.

  Moreover, according to this embodiment, the main-body part 56a has the through-hole 57 in the horizontal direction one side (left side). Exhaust gas flowing into the first chamber 61 from the inlet 52a and passing through the through hole 57 to one side (left side) in the second chamber 62 is formed into a concave portion 56b (particularly in the second chamber 62). The second concave portion 56b2) flows so as to wrap around the upper side and the lower side of the second concave portion 56b2), and reaches the discharge port 53a (particularly, the substantial opening portion 53a1) through the other side (right side) in the second chamber 62 (see FIG. 8 and the exhaust gas flow S1 to S5 shown in FIG. 9). Thereby, since the substantial flow distance (movement distance) of the exhaust gas from the through hole 57 of the partition plate 56 to the discharge port 53a of the housing 51 can be made relatively long, the pressure of the exhaust gas in the second chamber 62 Can be reduced efficiently, and as a result, the noise reduction effect of the muffler can be improved.

  Further, according to the present embodiment, the housing 51 (particularly, the second container 53) includes a convex portion 53p that protrudes outward so as to cover the discharge port 53a and has an opening 53q. A tubular exhaust gas passage 67 that guides exhaust gas from the discharge port 53a (particularly, the substantial opening 53a1) to the opening 53q blocks a part of the discharge port 53a among the convex part 53p and the bottom part 56bt of the concave part 56b. It is comprised by the part (exhaust gas channel | path formation part 56bt1). Thus, the exhaust duct, which is a separate member attached to the outer surface of the housing 51 (particularly, the second container 53), can be omitted, and the function of the duct can be realized by the exhaust gas passage 67. Therefore, the number of components of the duct can be reduced. Moreover, since the part which can function as the said duct can be formed only by combining the convex-shaped part 53p of the housing 51, and the waste gas passage formation part 56bt1 of the partition plate 56, compared with the former, formation of the said duct is carried out. The required work can be greatly reduced.

  Further, according to the present embodiment, the muffler 50 is connected to the exhaust port 36 of the engine 21 and has a box-shaped housing 51 having an inflow port 52a through which exhaust gas flows and an exhaust port 53a through which the exhaust gas flows out. A partition plate 56 that divides the interior of the housing 51 into a first chamber 61 including an inlet 52a and a second chamber 62 including an outlet 53a, and a flow that partially regulates the flow of exhaust gas in the second chamber 62. And a restriction unit 70. The partition plate 56 has at least one through hole 57 that communicates the first chamber 61 and the second chamber 62 on one side (left side) thereof. Exhaust gas flowing into the first chamber 61 from the inlet 52 a and passing through the through hole 57 to one side (left side) of the second chamber 62 flows around the flow restricting portion 70 in the second chamber 62. To the discharge port 53a (particularly, the substantial opening 53a1) through the other side (right side) in the second chamber 62 (see exhaust gas flows S1 to S5 shown in FIGS. 8 and 9). Thereby, since the substantial flow distance (movement distance) of the exhaust gas from the through hole 57 of the partition plate 56 to the discharge port 53a of the housing 51 can be made relatively long, the pressure of the exhaust gas in the second chamber 62 Can be reduced efficiently, and as a result, the noise reduction effect of the muffler can be improved.

  Further, according to the present embodiment, the flow restricting portion 70 is located between the discharge port 53 a (particularly, the substantial opening portion 53 a 1) and the through hole 57. Thereby, with a simple configuration, the substantial flow distance (movement distance) of the exhaust gas from the through hole 57 of the partition plate 56 to the discharge port 53a of the housing 51 can be made relatively long.

  Moreover, according to this embodiment, the main-body part 56a has the through-hole 57 in the horizontal direction one side (left side). Exhaust gas flowing into the first chamber 61 from the inlet 52 a and passing through the through-hole 57 to one side (left side) in the second chamber 62 flows into the second chamber 62 and flows into the first chamber 61. It flows so as to wrap around the upper side and the lower side, and reaches the discharge port 53a (particularly, the substantial opening portion 53a1) through the other side (right side) in the second chamber 62 (the exhaust gas flow shown in FIGS. 8 and 9). (See S1-S5). Thereby, since the substantial flow distance (movement distance) of the exhaust gas from the through hole 57 of the partition plate 56 to the discharge port 53a of the housing 51 can be made relatively long, the pressure of the exhaust gas in the second chamber 62 Can be reduced efficiently, and as a result, the noise reduction effect of the muffler can be improved.

Further, according to the present embodiment, the flow restricting portion 70 is a part of the partition plate 56 (concave portion 56b (particularly, the second concave portion 56b2)). Thereby, it is not necessary to use another member for forming the flow restricting portion 70, and as a result, an increase in the number of parts can be suppressed.
Further, according to the present embodiment, the flow restricting portion 70 is interposed between the housing 51 (particularly, the second container 53) and the partition plate 56 (particularly, the main body portion 56a) in the second chamber 62. . Thereby, in the 2nd chamber 62, the exhaust gas which flows from the left side part to the right side part can flow so that it may wrap around the upper part and the lower part of the flow control part 70 in the middle.

  In the present embodiment, in the second chamber 62, the exhaust gas flowing from the left side portion to the right side portion is in the middle of the flow restricting portion 70 (the concave portion 56b of the partition plate 56 (particularly, the second concave portion 56b2). )), An example of flowing around the upper and lower sides has been shown. However, regarding the path through which the exhaust gas flows, the flow regulating portion 70 (particularly the concave portion 56b of the partition plate 56 (particularly the second concave portion 56b2)) and What is necessary is just to be at least one below. That is, in the second chamber 62, the exhaust gas flowing from the left side portion to the right side portion is in the middle of the flow restriction portion 70 (the concave portion 56b of the partition plate 56 (particularly, the second concave portion 56b2)) or You may flow so that it may wrap around below.

In the present embodiment, the concave portion 56b (particularly, the second concave portion 56b2) of the partition plate 56 is described as an example of the flow restricting portion 70, but the configuration of the flow restricting portion 70 is not limited thereto. .
As another example of the flow restricting portion 70, instead of forming the second concave portion 56b2 in the partition plate 56, the second container 53 may be integrally formed so as to include a corresponding portion. In this case, the flow restricting portion 70 becomes a part of the housing 51 (particularly, the second container 53).

  As still another example of the flow restricting portion 70, the partition plate 56 is only the flat plate-like main body portion 56 a, and another member that replaces the above-described second concave portion 56 b 2 is replaced with the main body portion 56 a of the partition plate 56. It may be interposed between the inner surfaces of the two containers 53. In this case, the above-described separate member is interposed between the housing 51 (particularly, the second container 53) and the partition plate 56 in the second chamber 62 corresponding to the flow restricting portion 70.

  In the present embodiment, the brush cutter is described as an example of the portable work machine on which the muffler 50 is mounted. However, the portable work machine on which the muffler 50 is mounted is not limited thereto. For example, the muffler 50 can be mounted on a portable working machine such as a digger or a concrete cutter. Further, the muffler 50 can be mounted on a backpack type work machine such as a backpack blower, a sprayer (sprayer), a dusting machine, or a backpack type brush cutter.

In the present embodiment, the engine 21 is an OHV format four-stroke engine. However, the configuration of the engine 21 is not limited to this. For example, the engine 21 may be an OHC format engine.
Moreover, in this embodiment, although the cylinder head 28 and the cylinder part 22 were shown in the engine 21 as a separate body, it may replace with this and a cylinder head and a cylinder part may be integrated.

  As can be seen from the foregoing, the foregoing embodiments are merely illustrative of the present invention, and the present invention is made by those skilled in the art within the scope of the claims in addition to those directly shown by the described embodiments. Needless to say, it includes various improvements and changes.

DESCRIPTION OF SYMBOLS 1 Brush cutter 3 Engine module 11 Cover 21 Engine 36 Exhaust port 50 Muffler 51 Housing 52 First container 52a Inlet 53 Second container 53a Discharge port 53a1 Open part 53p Convex part 53q Open part 54, 55 Outer flange part 56 Partition plate 56a Body portion 56b Concave portion 56b1 First concave portion 56b2 Second concave portion 56bt Bottom portion 56bt1 Exhaust gas passage forming portion 56bt2 Exhaust gas guide portion 56bt3 Area 57 Through hole 58 Guide member 61 First chamber 62 Second chamber 65 Tubular Portion 65a Through-hole 67 Exhaust gas passage 70 Flow regulating portion S1 to S5 Flow of exhaust gas

Claims (11)

A box-shaped housing connected to the exhaust port of the engine and having an inflow port for exhaust gas flowing in, and an exhaust port for discharging the inflowing exhaust gas;
A partition plate that divides the housing into a first chamber including the inflow port and a second chamber including the discharge port;
Including
The partition plate includes a main body portion that is a flat plate shape, and a concave portion that protrudes from the main body portion toward the second chamber,
The main body has, on one side thereof, at least one through hole that communicates the first chamber and the second chamber;
The concave portion has at least a part of its bottom portion in contact with the inner surface of the second chamber in the housing,
The exhaust gas flowing into the first chamber from the inlet and passing through the through hole to the one side in the second chamber flows so as to wrap around the concave portion in the second chamber and the second chamber. An engine muffler that reaches the exhaust port through the other side of the room.   The engine muffler according to claim 1, wherein the concave portion is located between the discharge port and the through hole.   The engine muffler according to claim 1, wherein the concave portion is opposed to the inflow port. The inlet is located at the top of the first chamber;
The engine muffler according to claim 3, wherein the concave portion receives exhaust gas flowing into the first chamber from the inflow port and guides the exhaust gas downward. The main body has the through hole on one side in the lateral direction,
Exhaust gas flowing into the first chamber from the inlet and passing through the through-hole and reaching the one side in the lateral direction in the second chamber passes above and / or below the concave portion in the second chamber. The engine muffler according to any one of claims 1 to 4, wherein the engine muffler flows so as to wrap around and reaches the discharge port through the other side in the second chamber. The housing includes a convex portion that protrudes outward so as to cover the discharge port and has an opening,
The tubular exhaust gas passage for guiding exhaust gas from the exhaust port to the opening is constituted by the convex portion and a portion of the bottom of the concave portion that blocks a part of the exhaust port. The engine muffler according to claim 5. A box-shaped housing connected to the exhaust port of the engine and having an inflow port for exhaust gas flowing in, and an exhaust port for discharging the inflowing exhaust gas;
A partition plate that divides the housing into a first chamber including the inflow port and a second chamber including the discharge port;
A flow restricting portion for partially restricting the flow of exhaust gas in the second chamber;
Including
The partition plate has, on one side thereof, at least one through hole that communicates the first chamber and the second chamber;
The exhaust gas flowing into the first chamber from the inlet and passing through the through hole to the one side of the second chamber flows so as to go around the flow restricting portion in the second chamber. Engine muffler that reaches the exhaust port through the other side of the two chambers.   The engine muffler according to claim 7, wherein the flow restriction portion is located between the discharge port and the through hole. The partition plate has the through hole on one side in the lateral direction,
Exhaust gas flowing into the first chamber from the inlet and passing through the through hole to the one side in the lateral direction in the second chamber is above and / or below the flow restricting portion in the second chamber. The engine muffler according to claim 7, wherein the engine muffler flows so as to circulate around the exhaust gas and reaches the exhaust port through the other lateral side of the second chamber.   The engine muffler according to any one of claims 7 to 9, wherein the flow restriction part is a part of the partition plate or a part of the housing.   The engine muffler according to any one of claims 7 to 9, wherein the flow restricting portion is interposed between the housing and the partition plate in the second chamber.