JP2010043580A - Exhaust muffler of general purpose engine - Google Patents

Abstract

In an exhaust muffler disposed close to a cylinder of a general-purpose engine, it is possible to promote cooling of exhaust gas and enhance a silencing effect due to a decrease in exhaust gas pressure.
A muffler main body 15 connected to a cylinder 3 of a general-purpose engine E via an exhaust pipe 10 and disposed adjacent to the cylinder 3, and a first muffler chamber communicating with the exhaust pipe 10 through the inside of the muffler main body 15 16 and the exhaust member exposed to the outside of the muffler main body 15 while communicating between the first muffler chamber 16 and the second muffler chamber 17 and the partition member 19 partitioned into the second muffler chamber 17 communicating with the exhaust outlet 35 of the muffler main body 15. The cooling pipe 31 constitutes an exhaust muffler M for a general-purpose engine. When the exhaust gas moves from the first silencing chamber 16 to the second silencing chamber 17, the exhaust gas is effectively cooled by passing through the exhaust cooling pipe 31.
[Selection] Figure 5

Description

  The present invention relates to a muffler main body connected to a cylinder of a general-purpose engine via an exhaust pipe, a first muffler chamber communicating with the exhaust pipe inside the muffler main body, and a second muffler chamber communicating with an exhaust outlet of the muffler main body. The present invention relates to an improvement in an exhaust muffler for a general-purpose engine, which includes a partition member partitioned into two and a communication means for communicating between a first silencing chamber and a second silencing chamber.

Such an exhaust muffler for a general-purpose engine is already known as disclosed in Patent Document 1 below.
JP 2007-2730 A

  Generally, pressure reduction due to exhaust gas cooling is effective to enhance the noise reduction effect of engine exhaust gas. In motorcycles and automobiles, it is possible to form a sufficiently long exhaust pipe that communicates between the engine and the exhaust muffler. Therefore, while the exhaust gas from the engine passes through the exhaust pipe, the exhaust gas can be cooled to reduce the pressure.

  However, in a general-purpose engine as disclosed in Patent Document 1, it is necessary to arrange exhaust mufflers in close proximity to the cylinder so as to make the whole compact. Therefore, an exhaust pipe connecting the cylinder and the exhaust muffler is inevitable. However, it cannot be expected to cool the exhaust gas by the exhaust pipe.

  The present invention has been made in view of such circumstances, and is disposed in the vicinity of a cylinder of a general-purpose engine, but can promote the cooling of exhaust gas and can enhance the silencing effect due to the pressure drop of the exhaust gas. An object is to provide an exhaust muffler for an engine.

  To achieve the above object, the present invention provides a muffler body connected to a cylinder of a general-purpose engine via an exhaust pipe, a first muffler chamber communicating with the exhaust pipe in the muffler body, and an exhaust of the muffler body. In an exhaust muffler of a general-purpose engine, comprising: a partition member that partitions into a second silencing chamber that communicates with the outlet; and a communication means that communicates between the first silencing chamber and the second silencing chamber. The first feature is that the exhaust cooling pipe is exposed outside the muffler body while communicating between the second silencing chambers. The exhaust outlet corresponds to an exhaust outlet pipe 35 in an embodiment of the present invention described later.

  According to the present invention, in addition to the first feature, the exhaust cooling pipe has one end passing through one side wall of the muffler body connected to the exhaust pipe and opening to the first silencing chamber, while the other end is A second feature is that the first side wall and the first silencing chamber are disposed so as to open to the second silencing chamber.

  Further, in the present invention, in addition to the first or second feature, the exhaust cooling pipe exposed to the outside of the muffler main body is provided with a stage fixed to the cylinder together with the exhaust pipe. Three features.

  According to the first feature of the present invention, the exhaust gas flowing into the first silencing chamber from the exhaust pipe is cooled by passing through the exhaust connection pipe exposed outside the muffler body, and the exhaust gas generated by the cooling is cooled. Due to the pressure drop, the exhaust gas can be effectively silenced. Moreover, such a pressure drop of the exhaust gas not only silences, but also contributes to suppressing an afterburn phenomenon in which the unburned gas remaining in the exhaust muffler spontaneously ignites after the engine is stopped. In addition, the pressure drop due to the cooling of the exhaust gas can be achieved by exposing the exhaust cooling pipe communicating between the first silencing chamber and the second silencing chamber to the lower side of the muffler body, so that the volume of the muffler body is particularly expanded. This eliminates the need to increase the size of the exhaust muffler.

  According to the second feature of the present invention, the exhaust cooling pipe and the exhaust pipe are intensively attached to one side wall of the muffler body, so that the appearance of the exhaust muffler can be kept good.

  According to the third feature of the present invention, the exhaust cooling pipe is supported by the engine cylinder via the stay, and the vibration can be effectively suppressed. Moreover, since the stay is fixed to the cylinder by using the fixing of the exhaust pipe to the cylinder, the fixing means is simple and inexpensive.

  Embodiments of the present invention will be described based on preferred embodiments of the present invention shown in the accompanying drawings.

  1 is a front view of a general-purpose engine according to an embodiment of the present invention, FIG. 2 is a view taken in the direction of arrow 2 in FIG. 1, FIG. 3 is a view taken in the direction of arrow 3 in FIG. FIG. 5 is an enlarged sectional view of the exhaust muffler portion in FIG. 2, FIG. 6 is a sectional view taken along arrow 6 in FIG. 5, FIG. 7 is a sectional view taken along line 7-7 in FIG. 8 is a sectional view taken along line 8-8, FIG. 9 is a sectional view taken along line 9-9 of FIG. 5, and FIG. 10 is an exploded perspective view of a partition member in the exhaust muffler.

  1 to 4, an engine body 1 of a general-purpose engine E includes a crankcase 2 that has a mounting flange 2 a on a lower surface thereof and horizontally supports a crankshaft 4, and is slanted to one side from the crankcase 2. The cylinder 3 protrudes upward, and a flywheel 12 (see FIG. 4) and a cooling fan 13 superimposed on the front end are fixed to the front end of the crankshaft 4. The rear end portion of the crankshaft 4 is an output portion connected to various working machines.

  A recoil-type engine starter 5 that cranks the crankshaft 4 and a grill 14 for taking in outside air that covers the starter 5 are attached to the front side of the crankcase 2. The grill 14 has a large number of outside air intake holes, and a shroud 42 that is connected to the rear end of the grill 14 and defines a cooling air passage 41 around the cylinder 3 is attached to the crankcase 2 and the cylinder 3. Thus, according to the operation of the cooling fan 13, outside air, that is, cooling air is taken from the grille 14 and flows into the cooling air passage 41 to cool around the crankcase 2 and the cylinder 3, and then to the exhaust muffler M side described later. It comes to discharge.

  A fuel tank T disposed above the crankcase 2 and an intake air cleaner A and an exhaust muffler M adjacent to the fuel tank T immediately above the cylinder 3 are attached to the engine body 1.

  The cylinder 3 is joined to a cylinder block 3a connected to the crankcase 2, a cylinder head 3b having a combustion chamber 7 joined to an end surface of the cylinder block 3a and facing a piston 6 in the cylinder block 3a, and joined to the cylinder head 3b. The lower end flange 10a of the exhaust pipe 10 that communicates with the exhaust port 9 that communicates with the combustion chamber 7 is connected to the cylinder head 3b by bolts 11 and the head cover 3c that defines the valve operating chamber 8 therebetween. The exhaust muffler M is connected to the exhaust pipe 10. The exhaust pipe 10 is formed to be relatively short so that the exhaust muffler M can be disposed adjacent to the cylinder 3.

  The exhaust muffler M will be described with reference to FIGS.

  As shown in FIGS. 5 and 6, the exhaust muffler M is arranged along a diagonal line within the muffler body 15 and the muffler body 15. The exhaust muffler M is disposed in the muffler body 15 along one diagonal line. It is made of a synthetic resin or a steel plate that covers the outer surface of the muffler body 15 excluding the lower surface on the exhaust pipe 10 side, and is fixed to the muffler body 15 by a plurality of tapping screws 21, 21,. A muffler cover 20 is provided.

  The muffler body 15 includes a steel plate upper muffler half 15a and a lower muffler half 15b that are divided along one diagonal line. The caulked portion 22 on the outer periphery of the upper muffler half 15a is connected to the lower muffler half 15b. The two muffler halves 15a and 15b are joined by caulking to the outer flange 23. At this time, the partition member 19 is coupled to the muffler main body 15 by sandwiching the outer peripheral portion of the partition member 19 between the caulking portion 22 and the flange portion 23.

  A connecting bolt 28 protruding below the lower side wall is welded to the inner surface of the lower side wall of the lower muffler half 15b, and the lower muffler half 15b is formed by the connecting bolt 28 and a nut 29 screwed to the connecting bolt 28. , Fixed to the upper end flange 10b of the exhaust pipe 10. An exhaust inlet 25 for opening the exhaust pipe 10 to the first muffler chamber 16 is provided on the lower side wall of the lower muffler half 15b.

  An exhaust cooling pipe 31 bent in a U shape is welded to the lower side wall of the lower muffler half 15b. The upstream end 31a of the exhaust cooling pipe 31 passes through the lower wall of the lower muffler half 15b and opens in the middle in the vertical direction of the first muffler chamber 16, and the downstream end 31b is the lower wall of the lower muffler half 15b. , Through the first silencing chamber 16 and the partition member 19 and opening into the second silencing chamber 17. At that time, the exhaust cooling pipe 31 is welded around the through hole 36 of the partition member 19 through which the exhaust cooling pipe 31 passes. The periphery of the exhaust pipe 10 and the exhaust cooling pipe 31 exposed to the outside of the muffler main body 15 is a passage for the cooling air that has finished cooling the cylinder 3 as described above.

  As shown in FIGS. 5 and 6, a stay 43 is fixed by welding to a portion of the exhaust cooling pipe 31 exposed below the muffler body 15, and the stay 43 together with the lower end flange 10 a of the exhaust pipe 10, The bolt 11 is fixed to the cylinder head 3b.

  As shown in FIGS. 7-10, the partition member 19 consists of the upper partition half 19a and the lower partition half 19b made from a steel plate mutually joined. Between the half portions of the partition halves 19a and 19b, they are bulged outward to form a third silencing chamber 18, and the second silencing chamber 17 communicates with the third silencing chamber 18. The first communication holes 32, 32... Are provided in the upper partition half 19a. The third silencing chamber 18 is opened to the atmosphere via the exhaust outlet pipe 35.

  The exhaust outlet pipe 35 includes a pipe member 35a supported between the upper and lower partition halves 19a and 19b so as to cross the third silencing chamber 18, and an upper and lower partition half so as to communicate with the pipe member 35a. A pipe-like portion 35b bulging between the bodies 19a, 19b. The pipe-like portion 35b is arranged so as to penetrate between the joint surfaces of the upper and lower muffler halves 15a, 15b and to protrude outside. Is done. The pipe member 35 a is provided with a second communication hole 33, 33... Group that communicates the third silencing chamber 18 with the exhaust outlet pipe 35.

  As shown in FIG. 9, the muffler cover 20 is provided with a through hole 38 that receives the outer end opening of the exhaust outlet pipe 35, and a wire mesh spark arrester 39 that covers the through hole 38 is attached.

  Next, the operation of this embodiment will be described.

  In the exhaust stroke of the engine E, the exhaust gas exiting the combustion chamber 7 flows into the first silencing chamber 16 through the exhaust port 9, the exhaust pipe 10 and the exhaust inlet 25 in order, and then from the first silencing chamber 16 to the exhaust cooling pipe 31. To the second silencing chamber 17, then through the first communication holes 32, 32... To the third silencing chamber 18 and from the second communication holes 33, 33. It is discharged into the atmosphere. In this way, the exhaust gas is silenced by the damping action caused by multiple times of expansion during the sequential transition from the exhaust pipe 10 to the exhaust outlet pipe 35.

  What should be noted here is that the exhaust gas flowing into the first muffler chamber 16 from the exhaust pipe 10 is attached to the lower wall of the muffler body 15 and exposed to the outside air below the muffler body 15. The cooling is performed by passing through the pipe 31, and the pressure of the exhaust gas is reduced by the cooling, so that the exhaust gas can be effectively silenced. In addition, since the exhaust pipe 10 and the exhaust cooling pipe 31 are arranged in the path of the cooling air that has cooled the cylinder 3, the exhaust pipe 10 and the exhaust cooling pipe 31 can be effectively cooled by the cooling air. , The pressure drop due to the cooling of the exhaust gas flowing through them can be further promoted.

  Such a decrease in the pressure of the exhaust gas can not only mute but also bring about an effect of suppressing an afterburn phenomenon in which the unburned gas remaining in the exhaust muffler M spontaneously ignites after the operation of the general-purpose engine E is stopped.

  Further, the pressure drop due to the cooling of the exhaust gas can be achieved by exposing the exhaust cooling pipe 31 communicating between the first silencer chamber 16 and the second silencer chamber 17 to the lower side of the muffler body 15. The volume of the exhaust muffler M can be avoided from being enlarged.

  Further, the exhaust cooling pipe 31 communicating between the first silencing chamber 16 and the second silencing chamber 17 once passes through the lower side wall of the muffler main body 15 from the first silencing chamber 16 and then goes out downward, and then the lower cooling pipe again. The exhaust cooling pipe 31 is concentrated on the lower side wall of the muffler main body 15 together with the exhaust pipe 10 because it is disposed so as to penetrate the side wall and further pass through the first silencing chamber 16 and open to the second silencing chamber 17. Therefore, the exhaust cooling pipe 31 can be prevented from projecting to the side or the upper side of the muffler main body 15 and the appearance of the exhaust muffler M can be kept good.

  The present invention is not limited to the above embodiments, and various design changes can be made without departing from the scope of the invention. For example, the third silencing chamber 18 can be eliminated by directly communicating the second silencing chamber 17 with the exhaust outlet pipe 35.

The front view of the general purpose engine which concerns on the Example of this invention FIG. 2 is a view taken in the direction of arrow 2 in FIG. 1. FIG. 3 is a view taken in the direction of arrow 3 in FIG. Sectional drawing of the general purpose engine which follows the 4-4 line of FIG. The expanded sectional view of the exhaust muffler part in FIG. FIG. 6 is a view taken along arrow 6 in FIG. 5. FIG. 7 is a cross-sectional view taken along line 7-7 of FIG. FIG. 8 is a cross-sectional view taken along line 8-8 in FIG. 5. Sectional view taken along line 9-9 in FIG. The disassembled perspective view of the partition member in the said exhaust muffler.

Explanation of symbols

E engine M exhaust muffler 3 cylinder 10 exhaust pipe 15 muffler body 16 first silencer chamber 17 Second silencing chamber 19 ... partition member 31 ... exhaust cooling pipe (communication means)
35 ... Exhaust outlet (exhaust outlet pipe)
43 ... Stay

Claims (3)

A muffler body (15) connected to a cylinder (3) of a general-purpose engine (E) via an exhaust pipe (10), and a first silencing chamber communicating with the exhaust pipe (10) in the muffler body (15) (16), a partition member (19) partitioned into a second silencing chamber (17) communicating with the exhaust outlet (35) of the muffler body (15), a first silencing chamber (16), and a second silencing chamber (17 In the exhaust muffler of a general-purpose engine having communication means for communicating between them,
The communication means comprises an exhaust cooling pipe (31) that is exposed to the outside of the muffler body (15) while communicating between the first silencing chamber (16) and the second silencing chamber (17). Engine exhaust muffler. The exhaust muffler of the general-purpose engine according to claim 1,
The exhaust cooling pipe (31) has an upstream end (31a) that passes through one side wall of the muffler body (15) connected to the exhaust pipe (10) and opens to the first sound deadening chamber (16), while downstream thereof. An exhaust muffler for a general-purpose engine, characterized in that the end (31b) is disposed so as to pass through the one side wall and the first silencing chamber (16) and open to the second silencing chamber (17). The exhaust muffler for a general-purpose engine according to claim 1 or 2,
A stay (43) fixed to the cylinder (3) together with the exhaust pipe (10) is attached to the exhaust cooling pipe (31) exposed to the outside of the muffler body (15). , General-purpose engine exhaust muffler.

Images