JP5862010B2 - Engine muffler and engine working machine equipped with the muffler - Google Patents

Description

  The present invention relates to an engine muffler suitable for a portable engine working machine such as a chain saw and an engine working machine including the same.

  In recent years, exhaust gas regulations have become stricter for portable engine working machines such as chain saws. For this reason, as shown in Patent Document 1, for example, a technique for purifying exhaust gas by providing a catalyst inside the muffler is used.

JP 2002-242666 A

  By the way, when a catalyst is provided inside the muffler as in Patent Document 1, the exhaust gas becomes high temperature from the exhaust port of the muffler due to heat generation of the catalyst. For this reason, in order to lower the temperature of the exhaust gas discharged from the muffler, measures such as mounting a cover near the catalyst and increasing the distance from the catalyst to the exhaust port are taken. In this case, however, the size of the muffler increases and the weight increases. In particular, in a portable engine working machine, there is a problem that it is difficult to efficiently reduce the exhaust temperature because there are restrictions on dimensions and weight and an increase in dimensions and weight deteriorates workability.

  The present invention has been made in view of the above problems, and provides an engine muffler capable of lowering the exhaust temperature with a simple structure without increasing the size of the muffler, and an engine working machine equipped with the muffler. With the goal.

In order to achieve the above object, an engine muffler according to a first aspect of the present invention provides:
A first expansion chamber into which exhaust gas from the engine flows,
A second expansion chamber that is adjacent to the first expansion chamber, separated by a partition wall, and that communicates with the first expansion chamber via a communication path formed in the partition wall to which a catalyst is attached;
The second expansion chamber has a step formed so that the peripheral edge of the side surface facing the partition wall is closer to the partition wall than the central portion, and flows into the second expansion chamber at the peripheral edge. A plurality of exhaust ports for exhaust gas to flow outside are provided,
Exhaust gas that has flowed out of the plurality of exhaust ports comes into contact with outside air in a space between the peripheral edge portion and a surface obtained by enlarging the central portion to the outer peripheral side.
It is characterized by that.

  The plurality of exhaust ports may be provided at predetermined intervals in the peripheral edge.

  Furthermore, the catalyst may be provided at a substantially central portion of the partition wall.

  The communication path may be provided facing the side surface facing the partition wall.

  Further, the communication path may be provided substantially parallel to a direction in which exhaust gas from the engine flows into the first expansion chamber.

  In addition, a heat insulating plate may be provided so as to cover the side surface facing the partition wall of the second expansion chamber.

  Furthermore, a spark arrester may be provided between the side surface facing the partition wall of the second expansion chamber and the heat insulating plate.

  Further, it is preferable that the heat insulating plate, the spark arrester, the first expansion chamber, and the second expansion chamber are fastened together with the engine by a muffler mounting bolt.

An engine work machine according to a second aspect of the present invention includes the above-described engine muffler.
It is characterized by that.

Moreover, the engine muffler may be covered with a cover at a side surface adjacent to the side surface facing the partition wall.
An engine muffler according to a third aspect of the present invention is:
A first expansion chamber into which exhaust gas from the engine flows,
A second expansion chamber that is adjacent to the first expansion chamber, separated by a partition wall, and that communicates with the first expansion chamber via a communication path formed in the partition wall to which a catalyst is attached;
In the second expansion chamber, a step is formed so that the peripheral edge of the side surface facing the partition wall approaches the partition wall with respect to the central portion of the side surface, and flows into the second expansion chamber at the peripheral edge portion. A plurality of exhaust ports for exhaust gas to flow outside are provided,
A heat insulating plate is provided to cover the side surface of the second expansion chamber facing the partition wall;
A spark arrester is provided between the side surface facing the partition wall of the second expansion chamber and the heat insulating plate,
It is characterized by that.
Further, it is preferable that the heat insulating plate, the spark arrester, the first expansion chamber, and the second expansion chamber are fastened together with the engine by a muffler mounting bolt.

  According to the present invention, the second expansion chamber has a step formed so as to approach the partition wall with respect to a central portion at a peripheral portion of a side surface facing the partition wall to which the catalyst is attached, Since a plurality of exhaust ports for exhausting the exhaust gas flowing into the second expansion chamber to the outside are provided, the exhaust gas is diffused throughout the second expansion chamber and the exhaust gas is cooled using the entire chamber, and the peripheral edge By allowing exhaust gas to flow out from a plurality of exhaust ports, it is possible to cool the external air and exhaust gas in efficient contact with each other, and the exhaust temperature can be lowered with a simple structure without increasing the size of the muffler. it can.

The side view which showed a part of chain saw carrying the muffler which concerns on this invention in the cross section. Sectional drawing of the muffler of FIG. The front view of the muffler of FIG. The figure corresponding to FIG. 2 which shows the modification of this invention. Sectional drawing which expanded the principal part of FIG.

  Embodiments of the present invention will be described below with reference to FIGS. As shown in FIG. 1, an engine chain saw (engine work machine) 1 houses an engine 3 such as a two-cycle engine in an engine cover 2. A flat guide bar 5 for guiding a saw chain 4 protruding toward the front of the engine chain saw 1 (rightward in the figure) is attached from the engine cover 2. The engine cover 2 includes a hand guard 6 that extends upward (upward in the drawing) of the engine chain saw 1, a front handle 7 that is held by the operator above the engine cover 2, and a trigger 8 that adjusts the output of the engine. A rear handle 9 is provided. Further, a carburetor 10 for supplying an air-fuel mixture to the engine 3 is provided behind the engine 3 inside the engine cover 2 (right side in the figure, rear handle side). A muffler (engine muffler) 11 is provided in front of the engine 3. The muffler 11 is arranged so that the side surface (front surface) on the side away from the engine 3 protrudes outside the engine cover 2, and the surface adjacent to the side surface is covered with the engine cover 2. An oil tank chamber 33 is provided below the muffler 11.

  As shown in FIG. 2, a muffler 11 formed in a box shape is connected to an exhaust passage 13 formed in the cylinder block 12 of the engine 3. The muffler 11 is connected to the exhaust passage 13 by a partition wall 14 and has a first expansion chamber 16 provided with an exhaust inlet 15 through which exhaust gas flows, and a plurality of exhaust ports for exhausting the exhaust gas to the outside of the muffler 11. 17 is separated from the second expansion chamber 18 provided with 17. The first expansion chamber 16 and the second expansion chamber 18 communicate with each other through a communication path 20 to which a catalyst 19 provided on the partition wall 14 is fixed.

  The side surface 21 of the first expansion chamber 16 facing the engine 3 and the partition wall 14 are arranged substantially in parallel. Further, the side surface 22 of the second expansion chamber 18 facing the partition wall 14 has a peripheral edge portion 23 that approaches the partition wall 14 with respect to the central portion 24, that is, the central portion 24 protrudes outward with respect to the peripheral edge portion 23. A step is formed. The peripheral edge portion 23 and the central portion 24 are disposed substantially parallel to the partition wall 14 and the side surface 21 of the first expansion chamber 16, respectively. A wire mesh-like spark arrester 25 and a heat insulating plate 26 are attached to the outside of the side surface 22 facing the partition wall 14 of the second expansion chamber 18 so as to cover the side surface 22. The heat insulating plate 26 is provided with exhaust holes 27 having a smaller cross-sectional area than the exhaust ports 17 at positions corresponding to the respective exhaust ports 17. Further, a flange portion 28 is formed at the end of the second expansion chamber 18 on the first expansion chamber 16 side, and a caulking portion 29 is formed at the end of the first expansion chamber 16 on the second expansion chamber 18 side. . The first expansion chamber 16 and the second expansion chamber 18 are integrally coupled by caulking the flange portion 28 of the second expansion chamber 18 and the peripheral edge of the partition wall 14 by the caulking portion 29 of the first expansion chamber 16. 11 is configured. A pair of hollow support columns 30 are provided coaxially in the first expansion chamber 16 and the second expansion chamber 18, respectively, and a through hole (not shown) is formed in the partition wall 14 at a position corresponding to the support columns 30. Is formed. The muffler 11 is fixed to the engine 3 by fastening a bolt 31 that passes through the support pillar 30 and the through hole of the partition wall 14 to a female thread portion 32 formed in the cylinder block 12. The spark arrester 25 and the heat insulating plate 26 are fastened together with the muffler 11 by bolts 31.

  As shown in FIG. 3, a plurality of substantially circular exhaust ports 17 (only a part of the peripheral edge portion 23 of the side surface 22 facing the partition wall 14 of the second expansion chamber 18 of the muffler 11 are equally spaced along the periphery. (Shown in dotted lines). The heat insulating plate 26 covering the side surface 22 facing the partition wall 14 of the second expansion chamber 18 has a substantially circular exhaust hole having a smaller diameter than the exhaust port 17 so as to cover the exhaust port 17 substantially concentrically with the exhaust port 17. 27 is provided. The shapes of the exhaust port 17 and the exhaust port 27 are not limited to a substantially circular shape, and may be a rectangular shape or a slit shape. Further, the communication path 20 provided with the catalyst 19 of the partition wall 14 is disposed substantially at the center of the partition wall 14 and is disposed away from the peripheral edge portion 23 of the side surface 22 facing the partition wall 14 of the second expansion chamber 18. . In other words, the distance from the catalyst 19 to one side of the second expansion chamber 18 and the opposite side and the distance from the side adjacent to the one side and the opposite side are arranged to be substantially equal. Further, a pair of bolts 31 are provided on the left and right sides of the drawing with the communication path 20 in between, and the muffler 11 is fixed to the engine 3 together with the heat insulating plate 26 and the spark arrester 25.

  According to the muffler 11 configured as described above, when the engine 3 is started, the exhaust inlet 15 is provided from the exhaust passage 13 of the cylinder block 12 to the first expansion chamber 16 of the muffler 11 as indicated by a dotted arrow in FIG. Exhaust gas flows through. The exhaust gas that has flowed into the first expansion chamber 16 flows into the second expansion chamber 18 through the communication passage 20 of the partition wall 14. At this time, since the exhaust gas passing through the communication passage 20 passes through the catalyst 19 provided in the communication passage 19, the exhaust gas undergoes an oxidation reaction in the catalyst 19 and flows into the second expansion chamber 18 at a high temperature. The high-temperature exhaust gas that has flowed into the second expansion chamber 18 collides with the central portion 24 of the side surface 22 facing the partition wall 14 of the second expansion chamber 18 and then diffuses into the peripheral portion 23. Then, the exhaust gas guided to the peripheral portion 23 is discharged to the outside from the exhaust port 17 through the spark arrester 25 and the exhaust hole 27 of the heat insulating plate 26.

  A communication passage 20 provided with the catalyst 19 is disposed in the center of the partition wall 14, and the communication passage 20 faces the central portion 24 of the side surface 22 facing the partition wall 14 of the second expansion chamber 18. For this reason, the exhaust gas that has flowed into the second expansion chamber 18 can collide with the central portion 24 and be uniformly diffused into the second expansion chamber 18, and the exhaust gas can be efficiently exhausted using the entire interior of the second expansion chamber 18. It becomes possible to cool the gas. Then, the exhaust gas diffused into the second expansion chamber 18 passes through the spark arrester 25 from the exhaust port 17 of the peripheral portion 23, and is discharged to the outside through the exhaust port 27 of the small-diameter heat insulating plate 26 from the exhaust port 17. The For this reason, the exhaust gas can be discharged little by little from the exhaust hole 27. When the exhaust gas is discharged to the outside of the muffler 11, the contact area with the outside air increases, and the exhaust gas can be cooled more efficiently by the outside air. It becomes possible. Therefore, an increase in cost can be suppressed with a simple structure, and the temperature of the exhaust gas can be efficiently reduced without increasing the size and weight of the muffler 11. Further, the peripheral portion 23 of the second expansion chamber 18 of the muffler 11 provided with the exhaust port 17 and the exhaust hole 27 forms a step closer to the partition wall 14 with respect to the central portion 24, and the central portion 24 becomes the peripheral portion 23. On the other hand, it protrudes outward or the peripheral edge 23 is recessed with respect to the central part 24. For this reason, when the side surface 22 facing the partition wall 14 of the second expansion chamber 18 of the muffler 11 is pressed against a member to be cut such as wood during the cutting operation with the chain saw 1, the side surface 22 of the second expansion chamber 18 is The central part 24 contacts the member to be cut. Therefore, it is possible to secure a space between the member to be cut and the peripheral portion 23, and it is possible to prevent the exhaust port 17 and the exhaust hole 27 disposed in the peripheral portion 23 from being blocked, and efficiently. Exhaust is possible. In addition, even when the member to be cut is pressed against the muffler 11, a space can be secured between the member to be cut and the peripheral portion 23, and the exhaust is cooled using this space. In addition, overheating of the member to be cut can be suppressed. In addition, since the inflow direction of the exhaust gas from the engine 3 to the muffler 11 and the direction of the communication path are provided substantially in parallel, the area of the side surface of the second expansion chamber can be reduced while keeping the size of the muffler 11 small. The distance from the catalyst 19 to the discharge port 17 can be increased, and the exhaust gas can be cooled efficiently. Further, since the muffler 11 is covered with the engine cover 2 on the side adjacent to the side surface away from the engine 3, a cooling air passage can be formed between the muffler 11 and the engine cover 2. The muffler 11 can be efficiently cooled by the wind.

  In the above-described embodiment, a plurality of substantially circular exhaust holes 27 are formed in the heat insulating plate 26. However, the exhaust hole 27 is not limited to this configuration. For example, as shown in FIGS. 4 and 5, the exhaust hole 127 formed in the heat insulating plate 126 may be formed in a slit shape with a lid 128. In this case, the lid 128 is disposed so as to be inclined with respect to the exhaust hole 127, and the cover 128 causes the exhaust gas to flow out obliquely from the exhaust hole 127 along the inclination of the lid 128 as indicated by an arrow in FIG. Enable. In this case, the inclination direction of the lid 128 is inclined with respect to the plurality of exhaust holes 127 arranged above and below the peripheral edge 23 in FIG. 4 so as to flow in the same direction, for example, the direction in which the exhaust gas leaves the operator. It is preferable. Moreover, it is preferable to incline so that it may become the same direction with respect to the several exhaust hole 127 arrange | positioned on the right and left of the peripheral part 23 of FIG. And when comprised in this way, it becomes possible to cool the exhaust gas discharged | emitted from the muffler 11 efficiently like the above-mentioned case. Further, the direction of the exhaust gas flowing out can be controlled by the lid 128 so as to be directed to a wide space that is not suitable for an object to be cut or an operator, and the exhaust gas is discharged to a wide space to cool the exhaust gas more efficiently. In addition, it is possible to more effectively prevent the workpiece from being overheated. It is possible to improve workability by not exhausting the worker.

  In the above-described embodiment, the muffler 11 of the present invention is applied to the chain saw 1. However, the muffler 11 is not limited to being mounted on the chain saw 1, and may be used for other engine working machines such as a concrete cutter and a hedge trimmer. It may be mounted. Further, the shape of the muffler 11 is not limited to a substantially rectangular box shape, and may be a cylindrical shape. Furthermore, the structure which does not attach the spark arrester 25, the heat insulating material 26, or both to the muffler 11 may be sufficient. In addition, although the exhaust port 17 is configured to be disposed on the four sides of the peripheral portion 23 of the muffler 11, a configuration in which the exhaust port 17 is not provided in part may be used. For example, in the engine chain saw 1 according to the above-described embodiment, the oil tank 33 is provided on the lower side of the muffler 11, so that the exhaust port 17 is not provided on the lower side. By doing so, it becomes possible to reduce the influence on the components of the engine working machine.

DESCRIPTION OF SYMBOLS 1 Engine chain saw 2 Engine cover 3 Engine 11 Muffler 12 Cylinder block 13 Exhaust passage 14 Partition wall 15 Exhaust inlet 16 First expansion chamber 17 Exhaust port 18 Second expansion chamber 19 Catalyst 20 Communication path 21 Side surface 22 Side surface facing the partition wall of the second expansion chamber 23 Peripheral portion 24 Center portion 25 Spark arrester 26 Heat insulating plate 27 Exhaust hole 28 Flange portion 29 Caulking portion 30 Support column 31 Bolt 32 Female thread portion

Claims (12)

A first expansion chamber into which exhaust gas from the engine flows,
A second expansion chamber that is adjacent to the first expansion chamber, separated by a partition wall, and that communicates with the first expansion chamber via a communication path formed in the partition wall to which a catalyst is attached;
In the second expansion chamber, a step is formed so that the peripheral edge of the side surface facing the partition wall approaches the partition wall with respect to the central portion of the side surface, and flows into the second expansion chamber at the peripheral edge portion. A plurality of exhaust ports for exhaust gas to flow outside are provided,
Exhaust gas that has flowed out of the plurality of exhaust ports comes into contact with outside air in a space between the peripheral edge portion and a surface obtained by enlarging the central portion to the outer peripheral side.
An engine muffler characterized by this. The plurality of exhaust ports are provided at predetermined intervals in the peripheral edge portion.
The engine muffler according to claim 1. The catalyst is provided at a substantially central portion of the partition wall.
The engine muffler according to claim 1 or 2, characterized in that The communication path is provided facing the side surface facing the partition wall.
The engine muffler according to any one of claims 1 to 3, wherein the engine muffler is provided. The communication path is provided substantially parallel to a direction in which exhaust gas from the engine flows into the first expansion chamber.
The engine muffler according to claim 4. A heat insulating plate is provided so as to cover the side surface facing the partition wall of the second expansion chamber;
The engine muffler according to any one of claims 1 to 5, wherein A spark arrester is provided between the side surface facing the partition wall of the second expansion chamber and the heat insulating plate,
The engine muffler according to claim 6. The heat insulating plate, the spark arrester, the first expansion chamber, and the second expansion chamber are fastened together with the engine by a muffler mounting bolt.
The engine muffler according to claim 7. The engine muffler according to any one of claims 1 to 8,
An engine working machine characterized by that. The engine muffler is covered by a cover with a side surface adjacent to the side surface facing the partition wall.
The engine working machine according to claim 9, wherein A first expansion chamber into which exhaust gas from the engine flows,
A second expansion chamber that is adjacent to the first expansion chamber, separated by a partition wall, and that communicates with the first expansion chamber via a communication path formed in the partition wall to which a catalyst is attached;
In the second expansion chamber, a step is formed so that the peripheral edge of the side surface facing the partition wall approaches the partition wall with respect to the central portion of the side surface, and flows into the second expansion chamber at the peripheral edge portion. A plurality of exhaust ports for exhaust gas to flow outside are provided,
A heat insulating plate is provided to cover the side surface of the second expansion chamber facing the partition wall;
A spark arrester is provided between the side surface facing the partition wall of the second expansion chamber and the heat insulating plate,
An engine muffler characterized by this. The heat insulating plate, the spark arrester, the first expansion chamber, and the second expansion chamber are fastened together with the engine by a muffler mounting bolt.
The engine muffler according to claim 11.

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