JP2005201135A - Muffler for general engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a muffler for a general engine manufacturable in less manufacturing processes. <P>SOLUTION: A muffler body 21 is formed by combining a lower case body 21a and an upper case body 21b, the lower case body 21a has a bottom wall 22, an end wall 23, and sidewall pieces 24a and 25a, and the upper case body 21b has a top wall 26, an end wall 27, and sidewall pieces 24b and 25b. Each of the sidewall pieces 24a, 25a, 24b and 25b is tilted, and a flange section 32 disposed in the upper case body 21b is caulked with a flange section 31 disposed in the lower case body 21a, thereby combining two case bodies 21a and 21b. The end wall 27 and the flange section 32 connecting to this have a notch 41, and the notch 41 forms a drainage hole 42. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a muffler for a general-purpose engine that is applied to a general-purpose engine as a power source for construction equipment such as a generator or a rammer.

  General-purpose engines are used as power sources for construction equipment such as generators, mowers, rammers, and plate compactors. In a general-purpose engine, a muffler for reducing exhaust noise of exhaust gas discharged from an exhaust port of an engine body is attached to the engine body via an exhaust pipe as described in Patent Document 1, for example. ing. Conventional general-purpose engine mufflers each have a muffler body formed by joining a sheet metal lower case body and an upper case body at an opening, and an exhaust pipe is attached to the muffler body and a tail is formed inside. A pipe is incorporated.

On the other hand, general-purpose engines used as power sources for generators and construction machinery are often used outdoors, and are also used in rainy weather, so rainwater may enter the muffler from the tail pipe opening. . In addition, moisture contained in the exhaust gas may be condensed and collected in the muffler. In order to discharge the condensed water, for example, as described in Patent Document 2, a drain for draining water is provided in the muffler. Is provided.
Japanese Patent Laid-Open No. 10-266851 Japanese Patent Laid-Open No. 11-30120

  A conventional sheet metal muffler is configured such that a lower case body and an upper case body made of sheet metal each having a cup-shaped cross section are joined to each other at an opening side parallel to the bottom wall and the top wall of the case body. A flange portion is provided at the opening of the case body, and the flange portion of the other case body is bent, that is, crimped so as to cover the flange portion of the one case body. Therefore, the bent projection formed by caulking is formed along the outer periphery at the center in the vertical direction of the muffler body. For this reason, when the bolt is fastened to the flange provided at the tip of the exhaust pipe in order to attach the exhaust pipe protruding downward to the muffler main body to the engine main body, the bent protrusions interfere with the bolt fastening operation. It becomes.

  In addition, a drain hole is formed on the bottom surface of the lower case body by cutting and raising a part of the bottom wall downward to discharge moisture in the muffler to the outside. In order to form a drain hole, the manufacturing process of a lower case body will increase. In addition, when the drain hole is formed in the bottom wall, the engine body is placed underneath, so in order to prevent moisture from dripping into the engine body, it is necessary to attach a pipe for guiding moisture to the muffler body. There is.

  The objective of this invention is providing the muffler for general purpose engines which can be manufactured with few manufacturing processes.

  Another object of the present invention is to provide a muffler for a general-purpose engine that can easily perform the operation of attaching the muffler to the engine body.

  A muffler for a general-purpose engine according to the present invention is formed with a bottom wall, a first end wall connected to the bottom wall, and an opening side inclined from the tip of the bottom wall toward the tip of the end wall. From the lower case body having two side wall pieces, a top wall facing the bottom wall, a second end wall continuous to the top wall and facing the first end wall, and a tip of the top wall An opening side inclined toward the tip of the second end wall is formed and has two side wall pieces that are opposed to each other and that form a side wall by the side wall piece, and a muffler is formed by the lower case body. An upper case body constituting the main body, a flange portion formed on the opening side of one case body, and an opening side of the other case body, both of which are bent to the outside of the flange portion. A flange portion for connecting the case body, and And having a drain hole which is formed in the connecting portion of the wall and said second end wall.

  The muffler for a general-purpose engine according to the present invention is characterized in that the drain hole is formed by a notch provided in a part of the second end wall and the flange portion connected to the second end wall. The muffler for a general-purpose engine according to the present invention is characterized in that a drain hole is formed by a notch provided in a part of the bottom wall and the flange portion connected to the bottom wall.

  According to the present invention, by providing a notch in the flange portion for combining the two case bodies, a drainage hole can be formed in the bottom portion of the muffler body by caulking the flange portion, and the bottom wall is cut and raised. The muffler main body can be easily manufactured by a small number of manufacturing steps while eliminating the processing steps. Further, since the drain hole can be arranged on the end wall side of the muffler main body, the water can be surely discharged to the outside of the general-purpose engine without dripping water into the engine main body. Since the opening side that forms the side wall of the muffler main body is formed in a diagonal line shape, the protrusion between the top wall and the end wall of the protrusion formed by the flange portion for combining the two case bodies is the muffler main body. Therefore, when attaching the exhaust pipe to the engine body, it does not interfere with the operator, and the muffler can be easily attached. Since the end walls are formed by the walls constituting the respective case bodies, the tail pipe can be formed integrally with the end walls, and the number of parts can be reduced.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a front view showing an example of a general-purpose engine, and FIG. 2 is a plan view of FIG. The general-purpose engine shown in the figure is a single-cylinder four-cycle gasoline engine. A crankcase 12 in which a crankshaft 11 is rotatably incorporated is provided with a cylinder 13 constituting an engine body, and reciprocates in the cylinder 13. The crankshaft 11 is rotationally driven by a piston (not shown). The crankcase 12 is provided with a recoil starter 14 for starting the engine, and the engine can be started by rotating the crankshaft 11 by manually operating the recoil lever 15. The crankcase 12 is provided with a fuel tank 16 for containing fuel and an air cleaner 17 for purifying air supplied to the engine, and further reduces exhaust noise of exhaust gas discharged from the engine body. A muffler 18 is attached above the engine body. When this general-purpose engine is used as a drive source for construction equipment such as a plate compactor, the crankshaft 11 is connected to the diaphragm via a power transmission mechanism, and when used as a generator. A power generator is built inside.

  3 is a perspective view showing the muffler, FIG. 4A is a cross-sectional view of FIG. 3, and FIG. 4B is a right side view of FIG. 4A. The muffler 18 has a muffler main body 21 formed by a lower muffler half, that is, a lower case body 21a, and an upper muffler half, that is, an upper case body 21b. The lower case body 21 a includes a bottom wall 22, a first end wall 23 that is bent and continuous with the bottom wall 22, and two side wall pieces that are bent and continuous with the bottom wall 22 and the end wall 23 and face each other. 24a and 25a.

  On the other hand, the upper case body 21b includes a top wall 26 that faces the bottom wall 22, a second end wall 27 that bends and continues to the top wall 26, and that faces the end wall 23 and serves as a front wall; There are two side wall pieces 24b and 25b which are bent at the end wall 23 and are opposed to each other. The side wall pieces 24a and 24b form one side wall 24 of the muffler body 21, and the side wall pieces 25a and 25b form the muffler. The other side wall 25 of the main body 21 is formed.

  The opening side of the lower case body 21a has a substantially quadrangular shape, and the two side wall pieces 24a and 25a have opening sides inclined from the opening side of the bottom wall 22 toward the opening side of the end wall 23. Yes. The opening side of the upper case body 21b also has a substantially quadrangular shape corresponding to the lower case body 21a, and the two side wall pieces 24b and 25b are directed from the opening side of the top wall 26 toward the opening side of the end wall 27. And has an opening side inclined. Therefore, as shown in FIG. 4A, the lower case body 21a has an L-shaped cross section through the end wall 23 and the bottom wall 22 in a cross section passing through the end walls 23 and 27, and is perpendicular to this. In the cross section, the bottom wall 22 and the two side wall pieces 24a and 25a form a cup-shaped cross section, but the vertical lengths of the side wall pieces 24a and 25a differ depending on the cross-sectional position. The upper case body 21b has an L-shaped cross section due to the top wall 26 and the end wall 27. In the cross section shown in FIG. 4A, the muffler body 21 is a linear shape that connects diagonals of a substantially quadrilateral. The lower case body 21a and the upper case body 21b are brought into contact with each other.

  Each of the case bodies 21a and 21b is formed by pressing a blank material made of an iron plate with a press die. By pressing, a flange portion 31 is formed over the entire circumference of the opening side of the lower case body 21a, and a flange portion 32 is formed over the entire circumference of the opening side of the upper case body 21b. The The flange portion 31 of the lower case body 21a is formed with a width A as shown in FIG. 4A by pressing, and the flange portion 32 of the upper case body 21b is the same when pressed. In the figure, it is about twice as wide as the width A as shown by a two-dot chain line, and the width B is larger than the width A.

  The two case bodies 21a and 21b are bent or caulked so that the flange portion 32 of the upper case body 21b surrounds the flange portion 31 of the lower case body 21a in a state where the opening sides are abutted with each other. The two case bodies 21a and 21b are assembled to form the muffler main body 21, and the flange portions 31 and 32 and portions in the vicinity thereof serve as connecting portions for connecting the two case bodies 21a and 21b.

  Before connecting the two case bodies 21a and 21b, the exhaust pipe 33 is attached to the lower case body 21a, and the tail pipe 34 is attached to the upper case body 21b. The muffler main body 21 is fastened to the engine main body at a flange portion 35 provided in the exhaust pipe 33, and a mounting hole 36 through which a bolt passes is formed in the flange portion 35. The exhaust pipe 33 is formed with a discharge port 37 that discharges exhaust gas discharged from the exhaust port of the engine into the muffler main body 21, and the tail pipe 34 is an introduction port through which the exhaust gas discharged into the muffler main body 21 flows. 38 is formed, and a discharge port 39 opening in the end wall 27 is formed. Therefore, when the two case bodies 21 a and 21 b are combined, the exhaust pipe 33 and the tail pipe 34 are incorporated into the muffler main body 21.

  When the case body 21b is pressed, a notch 41 is formed in a part of the end wall 27 and the flange portion 32 connected thereto. Therefore, when the two case bodies 21 a and 21 b are combined, if the flange portion 32 is caulked so that the flange portion 32 surrounds the flange portion 31, a drain hole 42 is formed in the connection portion between the bottom wall 22 and the end wall 27. Thus, a part of the bottom wall 22 is opened from the end wall 27 to the outside. Since the end wall 27 is disposed at the end of the general-purpose engine, the water dropped from the drain hole 42 does not adhere to the engine body. In addition, since the notch 41 can be formed when the case body 21b is pressed, it is not necessary to process the drain hole after the case body 21b is pressed. A punch hole can be formed.

  When the exhaust pipe 33 is attached to the engine body, the bolt is passed through the attachment hole 36 of the flange portion 35 and the bolt is screwed manually. In that case, the exhaust pipe 33 is brought close to the end wall 23 side, and the protrusions formed by the flange portions 31 and 32 are linearly connecting the abutting surfaces of the upper and lower case bodies 21a and 21b diagonally. Therefore, it is provided at the upper end portion of the end wall 23 and is away from the exhaust pipe 33, so that the bolt can be easily fastened without interfering with the hand of the operator, and the assembly work of the general-purpose engine can be performed. Can be done quickly.

  FIG. 5A is a sectional view showing a muffler for a general-purpose engine according to another embodiment of the present invention, and FIG. 5B is a side view of FIG. In the illustrated muffler main body 21, a tail pipe 34 is formed integrally with the end wall 27, so that the assembly process of the tail pipe 34 with respect to the upper case body 21b is not required. When the upper and lower two case bodies are combined at a horizontal line portion substantially parallel to the bottom wall and the top wall, the tail pipe must be sandwiched at the opening side portion. As a result, the tail pipe 34 can be formed integrally therewith.

  FIG. 6 is a cross-sectional view showing substantially the same part as FIG. 4A of a general-purpose engine muffler which is another embodiment of the present invention. A partition plate 43 is incorporated inside the muffler main body 21. The partition plate 43 is divided into a lower silencing chamber 44a and an upper silencing chamber 44b, and the partition plate 43 is formed with a communication hole 45 for communicating both the silencing chambers 44a and 44b. When the partition plate 43 is incorporated in this way, a passage for causing the exhaust gas to meander between the two partition plates can be formed by stacking two partition plates each having a recess.

  FIG. 7 is a cross-sectional view showing a connecting portion of a muffler for a general-purpose engine that is another embodiment of the present invention. In each of the above-described embodiments, the flange portion 32 of the upper case body 21b is connected to this. Whereas the notch 41 is formed in the position portion of the end wall 27 to form the drain hole 42, in the case shown in FIG. 7, the bottom wall 22 and a part of the flange portion 31 connected thereto are shown. A water drain hole 42 is formed by forming a notch 41. Regardless of whether the notch is formed in the end wall 27 or the bottom wall 22, the notch can be formed at the time of pressing the case body by providing the notch in the flange portion connected to the notch.

  In each of the above-described embodiments, the width of the flange portion 32 of the upper case body 21b is set larger than the width of the flange portion 31 of the lower case body 21a, and the flange portion 32 is bent. However, the width dimension of the flange part 31 of the lower case body 21a is set larger than the width dimension of the flange part 32 of the upper case body 21b, and the flange part 31 is bent outside the flange part 32. You may do it. However, as shown in the drawing, by bending the flange portion 32 of the upper case body 21 b to the outside of the flange portion 31, the outer peripheral edge of the bent flange portion 32 is disposed below the flange portion 31. It is possible to prevent water from entering between the two case bodies 21a and 21b.

  8A is a cross-sectional view showing a conventional muffler body 51, and FIG. 8B is a right side view of FIG. 8A. As shown in FIG. 8, two cases constituting the muffler body 51 are shown. When the bodies 51a and 51b are respectively cup-shaped in cross section and the side wall pieces of both the case bodies 51a and 51b are open sides parallel to the top wall and the bottom wall, the cut-and-raised portion 52 is formed on the bottom wall of the lower case body 51a. It is necessary to form a drain hole and to form a drain hole in addition to the step of pressing the case body 51a. In the present invention, the flange portion 32 is provided with a notch. A drain hole can be formed. In addition, as shown in FIG. 8, when combined at the center in the vertical direction, the projection of the flange approaches the exhaust pipe, and the projection interferes with the work of attaching the exhaust pipe to the engine body. However, in the present invention, the muffler can be easily attached without causing interference of the protrusions.

  The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the invention. For example, in the illustrated case, the horizontal dimension of the side walls 24 and 25 is longer than the horizontal dimension of the end walls 23 and 27, but the dimension of the side walls 24 and 25 may be shortened. The dimensions can be set arbitrarily. Further, the muffler body 21 may be attached to the engine, and a muffler cover may be attached so as to cover the muffler body 21.

It is a front view which shows an example of a general purpose engine. It is a top view of FIG. It is a perspective view which shows a muffler. (A) is sectional drawing of FIG. 3, (B) is a right view of FIG. 4 (A). (A) is sectional drawing which shows the muffler for general purpose engines which is other embodiment of this invention, (B) is a side view of FIG. 5 (A). It is sectional drawing which shows the part substantially the same as FIG. 4 (A) of the muffler for general purpose engines which is other embodiment of this invention. It is sectional drawing which shows the connection part of the muffler for general purpose engines which is other embodiment of this invention. (A) is sectional drawing which shows the conventional muffler, (B) is a right view of FIG. 8 (A).

Explanation of symbols

21 Muffler body 21a Lower case body 21b Upper case body 22 Bottom wall 23 End wall (back wall)
24 Side wall 24a, 24b Side wall piece 25 Side wall 25a, 25b Side wall piece 26 Top wall 27 End wall (front wall)
31 Flange part 32 Flange part 33 Exhaust pipe 34 Tail pipe 41 Notch 42 Drain hole

Claims (3)

A bottom wall, a first end wall connected to the bottom wall, and a bottom wall having two side wall pieces facing each other formed with an opening side inclined from the tip of the bottom wall toward the tip of the end wall The case body,
The top wall facing the bottom wall, the second end wall connected to the top wall and facing the first end wall, and inclined from the tip of the top wall toward the tip of the second end wall An upper case body that has two side wall pieces that form side walls by the side wall pieces and that have an opening side that is opposed to each other, and that constitutes a muffler body with the lower case body,
A flange formed on the opening side of one of the case bodies;
A flange portion that is formed on the opening side of the other case body and is bent outside the flange portion to connect both the case bodies,
A muffler for a general-purpose engine having a drain hole formed in a connection portion between the bottom wall and the second end wall.   The muffler for a general-purpose engine according to claim 1, wherein the drainage hole is formed by a notch provided in a part of the second end wall and the flange portion connected to the second end wall. Muffler. The muffler for general-purpose engines according to claim 1, wherein a drainage hole is formed by a notch provided in a part of the bottom wall and the flange portion connected to the bottom wall.

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