JPH0788775B2 - Exhaust muffler - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an exhaust muffler for reducing engine exhaust noise, and more particularly to an exhaust muffler having a suitable mounting structure.

<Prior Art> An exhaust muffler of an engine is designed to reduce exhaust noise by volume expansion, resonance damping, etc. of exhaust gas in a silencing chamber formed inside the engine. Conventionally, especially in a small general-purpose engine, etc., it is common to assemble the exhaust muffler directly to the engine.At the same time as aligning the exhaust introduction port of the muffler with the exhaust port opened on the engine side, The stud balts erected on the muffler side is inserted into the hole formed in the mounting flange on the muffler side, and the nut is screwed to the stud bolt.

However, the work of screwing the nut onto the stud bolt must be performed in a relatively narrow gap between the engine side and the muffler, and the assembling work tends to be complicated.

Therefore, a structure has been proposed in which a stud bolt that penetrates the muffler is erected on the engine side, and a nut is screwed onto the stud bolt from the outer surface of the muffler. For example, Japanese Patent Application No. 61-089066 by the same applicant is proposed. An example is shown in the specification. However, in the case of such a muffler,
To prevent the muffler from being deformed by the tightening force of the nut, a reinforcing member such as a metal collar provided on the outer circumference of the stud bolt must be separately provided in the muffler, which increases the number of parts and the number of assembly steps. Muffler tends to be heavy.

<Problems to be Solved by the Invention> In view of the above-described problems of the prior art, the main object of the present invention is to easily assemble the engine, reduce the number of parts, and reduce the weight. May provide exhaust muffler.

<Means for Solving the Problems> According to the present invention, such an object is to provide a casing that internally defines a muffling chamber, an exhaust introduction pipe that connects the muffling chamber to an exhaust port of an engine, and the muffling member. An exhaust muffler having an outlet passage communicating the chamber with the atmosphere, wherein the exhaust introduction pipe has a base end fixed to the engine side, and a free end protruding into the muffling chamber from an opening of the casing. Corresponding screw means for screwing with each other is provided on each of the most idle end of the exhaust gas introducing pipe and the casing,
Moreover, the opening of the casing is fitted to the expanded diameter shoulder portion of the exhaust introduction pipe, and by fitting the both corresponding screw means to each other, the fitting between the opening and the expanded diameter shoulder portion is performed. This is achieved by providing an exhaust muffler characterized by a tightness.

<Operation> In this way, the exhaust introduction pipe is assembled to the muffler only by fixing the free end portion of the exhaust introduction pipe and the muffler to each other, and at the same time, the muffler is assembled to the engine side.

<Embodiment> Hereinafter, the present invention will be described in detail with reference to the accompanying drawings with reference to specific embodiments.

1 to 3 show a muffler 1 according to the present invention. The muffler 1 has a substantially box-like shape, and has an exhaust introduction pipe 2 to be described later.
4 and the exhaust introduction pipes 2 to 4 and a flange 5 integrally fixed to the cylinder head 6 of a three-cylinder engine (not shown).

The casing 7 of the muffler 1 is composed of an outer half body 8 made of glass wool and an inner half body 9 in which a grass worm layer 10 is lined on the inner surface of a reinforcing outer plate 11 made of a steel plate or the like.
As shown in FIG. 2 as seen from the line II-II together, the outer half body 8 and the inner half body 9 are separated by caulking the edge portion 12 of the reinforcing outer plate 11 inward. The edge portions of partition walls 13 and 15, which will be described later, and the outlet pipe 21 are sandwiched and fixed to each other.

Inside the casing 7, a first empty chamber 18 is defined by the inner half body 9 and the partition wall 13, and the outer circumference of the outlet pipe 21 is surrounded by the partition wall 13 and the partition wall 13.
A second void chamber 19 is defined by surrounding 15 from both directions, and a third void chamber 20 is defined between the outer half body 8 and mainly the partition wall 13. Since the large number of small holes 14 are formed in the portion of the partition wall 13 that faces the inner half body 9, the first empty chamber 18 and the second empty chamber 19 communicate with each other, and the outer half body 8 of the partition wall 15 is communicated with each other.
Since the large number of small holes 16 are formed in the portion facing the second space 19, the second empty space 19 and the third empty space 20 communicate with each other. The outer end 24 of the outlet pipe 21 having the flange 22 communicates with the atmosphere via an exhaust pipe (not shown), and the flared inner end 23 of the outlet pipe 21 opens toward the third chamber 20. ing.

As best shown in FIG. 2, the outer half body 8, the partition wall 13, and the inner half body 9 have openings 25, 26 for coaxially blending so as to correspond to the exhaust gas introduction pipes 2 to 4, respectively. 3 sets of 27 are opened. A cylindrical spacer 30 having a flange that expands toward the inner and outer surfaces of the outer half body 8 is fitted into the opening 25 by caulking. An annular projecting portion 28 projecting toward the vacant chamber 20 side is formed in a portion of the partition wall 13 around the opening 26, and an outer end of the annular projecting portion 28 is fitted with a base end portion having an outward flange of the tubular member 31, And it is fixed by welding. The free end portion of the tubular member 31 having the inward flange is in contact with the inner end of the cylindrical spacer 30. By crimping the reinforcing outer plate 11 inwardly in the opening 27, the reinforcing annular member 32 is formed.
Is stuck.

As shown in FIG. 2, the exhaust introduction pipe 3 has a small diameter portion.
33, a large diameter portion 34, and a taper shoulder portion 35 connecting these portions, and a screw member 37 having a screw hole 38 at its free end is fixed to the end portion on the small diameter portion 33 side. The flange 5 is fixed by caulking to the end portion on the large diameter portion 34 side. Also,
A pair of notches 41 are provided at diagonal positions in the hole 40 that receives the end of the flange 5 on the side of the large diameter portion 34, and the pipe wall of the exhaust introduction pipe 3 is caulked toward the inside of the notch 41. The rotation of the exhaust introduction pipe 3 is prevented. On the side wall of the small diameter portion 33, a pair of long holes 42 are formed at positions perpendicular to each other. An inward flange 43 is provided at the end on the small diameter portion 33 side.

The female screw member 37 is inserted into the exhaust introduction pipe 3 from the end portion on the large diameter portion 34 side, has a screw hole 38, and has a free end protruding from the end portion on the small diameter portion 33 side. Further, the shoulder portion of the enlarged diameter portion 44 formed on the proximal end side of the female screw member 37 is welded in a state of being in contact with the inward flange 43, so that the female screw member 37 is fixed to the exhaust gas introducing pipe 3. ing. Here, the exhaust introduction pipes 2 to 4 have the same structure, and three exhaust introduction pipes are fixed to the mounting flange 5 similarly to the above (FIGS. 1 and 3).

As well shown in FIG. 2, the muffler 1 is fitted to the exhaust gas introduction pipe which is previously fixed to the cylinder head 6 of the engine by screwing through the mounting flange 5. Then, the bolt 45 is screwed into the screw hole 38 from the outside of the muffler 1 through the opening 25. Here, the length from the outer end portion of the opening 27 to the inner end surface of the opening 25 is longer than the length from the tapered shoulder portion 35 of the exhaust introduction pipe 3 to the free end surface of the female screw member 37. Also,
The length from the outer end surface of the opening 27 to the end surface of the opening 26 on the vacant chamber 18 side is longer than the length from the taper shoulder portion 35 of the exhaust introduction pipe 3 to the outer end surface of the inward flange 43. Therefore, when the bolt 45 is tightened, the tapered shoulder portion 35 first comes into contact with the end edge of the opening 27, and by further tightening the bolt 45 from the outside, the inner half body 9 is elastically deformed slightly and the inward flange 43 is opened. Abut. At this time, due to the restoring force of the inner half body 9, the tapered shoulder portion 35 is tightly fitted in the opening 27, and the opening is suitably sealed.

The exhaust introduction pipes 2 and 4 are bolted to the muffler 1 in the same manner as described above, and the fixation of the exhaust introduction pipes 2 to 4 to the muffler 1 is completed. Further, since the exhaust introduction pipes 2 to 4 are fixed to the cylinder head 6 of the engine in advance, the work of fixing the muffler 1 to the cylinder head 6 of the engine is also completed by performing the above work.

Here, as shown in FIG. 1 and FIG. 3, one of the pair of elongated holes 46 as the exhaust introduction port of the exhaust introduction pipe 2 is directed toward the outlet pipe 21 side and the other is directed toward the exhaust introduction pipe 3 side. Has been opened for. Further, the pair of elongated holes 42 of the exhaust gas introducing pipe 3 are opened such that one of them is directed toward the outlet pipe 21 and the other is directed toward the exhaust gas introducing pipe 2. Furthermore, the pair of long holes 47 of the exhaust introduction pipe 4 are
One of them is opened toward the exhaust introduction pipe 3 side and the other is opened toward the outlet pipe 21 side.

Exhaust gas discharged from an exhaust port (not shown) passes from the cylinder head 6 through the exhaust introduction pipes 2 to 4, and the elongated holes 42, 4
Vacancy 18 is entered from 6 and 47. Then, it proceeds from a large number of small holes 14 formed in the partition wall 13 to the vacant chamber 19, and further proceeds to a vacant chamber 20 via a large number of small holes 16 formed in the partition wall 15. Outlet pipe from vacant room 20
It enters into 21 and is discharged into the outside air through the outlet side opening 24. During this time, the exhaust noise of the exhaust gas is reduced by the volume expansion of each chamber and the volume expansion and resonance damping due to the passage of small holes.

In this embodiment, three exhaust gas introduction pipes are provided for each cylinder of the engine, but for example, these may be combined to provide only one exhaust gas introduction pipe, and a large number of exhaust gases may be provided depending on the number of cylinders. An introduction pipe may be provided.

<Effects of the Invention> As described above, according to the present invention, the exhaust introduction pipe is assembled to the casing and the muffler is assembled to the engine side only by the operation of fastening the free end of the exhaust introduction pipe to the casing of the muffler. Therefore, assembly workability is improved. Further, since the exhaust introduction pipe serves as a fixing member for fixing the muffler to the engine side as it is, the number of parts is reduced and the muffler is lightened. From the above, the effect is extremely large.

[Brief description of drawings]

FIG. 1 is a side sectional view showing a state in which an exhaust muffler according to the present invention is fixed to a cylinder head. FIG. 2 is a view of FIG. 1 taken along the line II-II. FIG. 3 is a view showing only a main part of FIG. 1 seen from the line III-III. 1 ... Muffler, 2-4 ... Exhaust introduction pipe 5 ... Mounting flange, 6 ... Cylinder head 7 ... Casing, 8 ... Outer half 9 ... Inner half, 10 ... Glass wool layer 11 ... Reinforcement skin, 12 …… Edge 13 …… Partition wall, 14 …… Small hole 15 …… Bulkhead, 16 …… Small hole 18-20 …… Vacancy, 21 …… Outlet pipe 22 …… Flange, 23… … Inner end 24 …… Outer end, 25 to 27 …… Opening 28 …… Annular protrusion, 30 …… Cylindrical spacer 31 …… Cylindrical member, 32 …… Annular member 33 …… Small diameter part, 34 …… Large Diameter 35 …… Tapered shoulder, 37 …… Female thread member 38 …… Screw hole, 40 …… Hole 41 …… Notch, 42 …… Oval hole 43 …… Inward flange, 44 …… Expanding section 45 …… Bolts, 46, 47 ... elongated holes

Claims (2)

[Claims] 1. An exhaust muffler having a casing defining a muffler chamber, an exhaust gas introducing pipe communicating the muffler chamber with an exhaust port of an engine, and an outlet passage communicating the muffler chamber with the atmosphere. The exhaust introduction pipe has a base end fixed to the engine side and a free end protruding into the muffling chamber from an opening of the casing, and the exhaust end of the exhaust introduction pipe and the casing Corresponding screw means to be screwed with each other are provided, and the opening of the casing is fitted to the enlarged diameter shoulder portion of the exhaust introduction pipe, and by fastening both corresponding screw means to each other. An exhaust muffler characterized in that the fitting between the opening and the enlarged diameter shoulder portion is made tighter. 2. The screw means on the casing side is screwed with the corresponding screw means on the exhaust introduction pipe side via a collar provided upright on a partition wall of the casing. Exhaust muffler according to item 1 of the above.