JPH0223775Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a muffler in a general-purpose engine used in a power pest control machine, a lawn mower, an agricultural working machine, a portable generator, etc.

[Prior art and its problems]

Generally, the casing of a muffler for a general-purpose engine has an exhaust gas inlet on one side, an exhaust gas outlet on the other side, and a partition plate with an exhaust gas vent in the middle.

Inside this muffler housing, a through pipe for muffler mounting bolts is installed, and a noise-reducing exhaust gas passage is formed (for example,
-17314, Utility Model Application Publication No. 56-83628), the structure is complicated and manufacturing is extremely troublesome.

For this reason, recently, as shown in Fig. 1, a sound deadening pipe 3, which is a two-piece half pipe that integrates the through pipe 1 of the muffler mounting bolt and the sound deadening exhaust gas passage 2, is installed inside the muffler housing. It is being held.

By the way, this muffling pipe 3 is rapidly heated and expands due to the direct action of high-temperature exhaust gas passing through the exhaust gas passage 2 and the large heat receiving area of the passage, while the bolt 6 in the through pipe 1 has a large heat receiving area. Because it is small and has a large heat capacity, thermal expansion is slow. This temporal difference in thermal expansion between the two causes an increase in the axial force of the bolt 6, especially when the engine is started, causing a problem in which the flat plate portion 4 and the through pipe 1 easily buckle outward. This sagging problem is caused by
When the engine is cold after the engine has stopped, the muffler attachment becomes loose, leading to gas leakage when the engine is restarted, causing the muffler to rattle and even break.

In order to eliminate such problems, as shown in Fig. 2, spot welding 7 is applied to the flat plate part 4 separating the through pipe 1 and the noise-muffling exhaust gas passage 2 to improve the strength of the mating surfaces. However, this results in a significant increase in cost.

[Purpose of invention]

This invention was made to solve the above problem, and the through pipe of the muffler mounting bolt is extended on one side of the abutting part of two sound deadening pipes and rolled outward alternately by press working. It is an object of the present invention to provide a muffler for a general-purpose engine that has a muffler that is formed into a cylindrical shape and has a muffler pipe that is stronger than conventional structures to withstand fatigue and deformation during thermal expansion.

[Structure of the idea]

One embodiment of a muffler for a general-purpose engine according to the present invention will be described with reference to FIGS. Exhaust gas outlet 13
The outer casing 14 having the exhaust gas vent 15 is butted against the partition plate 16 having the exhaust gas vent 15 therebetween, and the periphery thereof is crimped and fixed to form the muffler chambers 17 and 1 inside.
8. The exhaust gas vent 15 of the partition plate 16 is offset from the exhaust gas inlet 11 and the exhaust gas outlet 13 so as not to overlap with each other.

Inside the muffler housing 10, an exhaust gas passage 20 with a circular cross section is formed by combining two half pipes 19, and the muffler is mounted by extending one side of each abutting part and winding them alternately outward in a circular shape. A muffling pipe 24 is held, which forms a through pipe 22 of the bolt 21 and has an exhaust gas vent 23 formed by shallowly cutting the front half of the other side of each abutting portion in the longitudinal direction. That is, the sound-muffling pipe 24 is passed through a through-hole 25 having the same external shape as the sound-muffling pipe 24 bored in the lower part of the partition plate 16, and its front end is inserted into the outer casing 12 and protrudes outward from the periphery of the exhaust gas inlet 11. It abuts against a backing plate 28 having an exhaust gas vent 27 inserted into the section 26, and its rear end is fitted into and held by an inner protrusion 29 provided at the lower part of the outer casing 14.

Muffler attachment bolts of the noise-reducing pipe 24 are passed through both upper and lower sides of the exhaust gas introduction hole 11 of the outer protrusion 26, upper and lower sides of the exhaust gas vent 27 of the backing plate 28, and upper and lower sides of the inner protrusion 29, respectively. A bolt insertion hole 30 that matches the pipe 22 is provided.

In addition, although the exhaust gas passage 20 of the muffler pipe 24 in the muffler of the above embodiment has a circular cross section,
The exhaust gas passage 20' is not limited to this, but may have a rectangular cross section as shown in FIG. 6, for example.
Furthermore, the exhaust gas passage 20'' may have an oval cross-section as shown in FIG. A rectangular through pipe 22' may also be used.

[Effect of invention]

The general-purpose engine muffler of the present invention configured as described above has an exhaust gas vent 2 in the center on the end face of the exhaust pipe 31 of the engine, as shown in FIG.
7' is installed with a gasket 32 having bolt insertion holes 30' formed above and below it. That is, the outer protrusion 26 is brought into contact with the end surface of the exhaust pipe 31 via the gasket 32, the exhaust gas inlet 11 is aligned with the exhaust pipe 31, and the muffler mounting bolts 21 are tightened.
the bolt insertion hole 30 of the outer casing 14, and the sound deadening pipe 24.
The through pipe 22, the bolt insertion hole 3 of the backing plate 28
0, bolt insertion hole 30 of outer casing 12, gasket 3
The muffler is mounted by passing through the bolt insertion holes 30' of No. 2 and screwing them into the bolt holes 33 on the end face of the exhaust pipe 31.

In the muffler of the present invention mounted on the end face of the exhaust pipe 31 in this way, the exhaust gas is passed through the gasket 32.
It enters the exhaust gas passage 20 of the muffling pipe 24 through the exhaust gas vent 27', the exhaust gas inlet 11 of the outer casing 12, and the exhaust gas vent 27 of the backing plate 28,
Half pipe 1 forming the passage 20 from here
It enters the muffler chamber 17 in the outer casing 12 through the exhaust gas vent hole 23 on the other front half of the butt part 9, and further passes through the exhaust gas vent hole 15 of the partition plate 16 into the muffler chamber 18 in the outer casing 14. The exhaust gas enters the interior and is discharged to the outside from the exhaust gas outlet 13.

In the flow of exhaust gas inside the muffler, the open end 34 of the through pipe 22 of the muffler mounting bolt 21, that is, the circular wrapped tip 34 of the through pipe 22, is not directly affected by the high temperature exhaust gas released from the engine. , the temperature difference with the bottle 21 is relatively small. Furthermore, since the portion of the exhaust gas passage 20 that does not have the exhaust gas vent 23 and the through pipe 22 of the bottle 21 are wound in opposite directions, the rigidity of the half pipe itself is high. Furthermore, the through pipe 22 has high rigidity because it is almost completely wrapped around a single plate. Therefore, even if the axial force of the mounting bolt 21 increases due to rapid thermal expansion of the muffling pipe 19 when the engine is started, it will not easily buckle.

[Effect of idea]

In the general-purpose engine muffler of this invention, the through-pipe of the mounting bolt is formed into a cylinder by winding a single plate through press processing, and the exhaust gas directly passes through the circular winding tip, which is weakest against sagging during thermal expansion. Because it is located outside to prevent the noise from acting and to slow down heating and thermal expansion, even if the silencing pipe is rapidly heated and expands, causing an increase in the axial force of the bolt, it will not easily buckle. Therefore, the muffler installation will not loosen even when the engine is cold after stopping, and there will be no damage or problems after restarting.

In addition, in the muffler of the present invention, the through pipe for the muffler mounting bolt is formed by winding the extension of one side of the butt part of the half pipe outward, so the through pipe for the muffler mounting bolt is There is no need for spot welding between the pipe and the muffler exhaust gas passage, so the muffler and the muffler can be manufactured easily and inexpensively.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of a muffler pipe held inside a muffler of a conventional general-purpose engine, Fig. 2 is a sectional view of a conventional improved type of muffler pipe, and Fig. 3 is a muffler of a general-purpose engine according to the present invention. FIG. 4 is a cross-sectional view taken along line A-A in FIG. 3, FIG. 5 is a cross-sectional view taken along line B-B in FIG. 3, and FIGS. FIG. 7 is a sectional view showing another example of the muffler pipe in the muffler of the present invention. 10...Muffler housing, 11...Exhaust gas inlet, 13...Exhaust gas outlet, 15...Exhaust gas vent, 16...Partition plate, 19...Half pipe, 2
0... Exhaust gas passage, 21... Muffler attachment bolt, 22... Penetration pipe, 23... Exhaust gas vent, 24... Silence pipe.

Claims (1)

[Scope of utility model registration request] In a muffler that is attached to an engine with bolts that pass horizontally through the muffler body, which has a muffler chamber partitioned into front and rear muffler chambers by a vertically placed partition plate, a half-split that passes through the partition plate and is supported within the muffler body. A general-purpose engine characterized in that two pipes are joined together to form an exhaust gas passage, and extensions on one side of each abutting part of the pipes are wound outward alternately to form a through pipe for a muffler mounting bolt. muffler.