JP2002266624A - Muffler - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently lower temperature of exhaust gas and reduce draft noise. SOLUTION: In the muffler having a housing 2 and an inner pipe 3 piercing through the housing 2 and held by it, a bulkhead 6 is provided in the inner pipe 3, orifices 4 are formed upstream of the bulkhead, and inflow ports 5 are formed downstream of the bulkhead. The orifices 4 are arranged so diameters gradually become smaller as they approach the bulkhead 6, and the inflow ports 5 are arranged so diameters gradually become smaller as they approach the bulkhead 6.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a muffler for reducing exhaust noise of an internal combustion engine.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 9, a silencer 101 for an internal combustion engine has an inner pipe 1 inside a housing 102.
A silencer chamber 104 is formed by penetrating the silencer 103, and a partition 107 is provided in the inner pipe 103, and an outflow hole 105 is formed upstream of the partition and an inflow hole 106 is formed downstream, thereby introducing the muffler 101. Outflow portion 108 in which the exhaust gas G flows out to the sound deadening chamber 104 through the outflow hole 105
The structure in which the inner pipe 103 is partitioned into an inflow portion 109 through which the exhaust gas flowing out to the muffling chamber 104 is discharged through the inflow hole 106 to the outside of the muffler 101 is described in
8-114810.

In the conventional silencer, the expansion of the exhaust gas when the exhaust gas flows from the small-volume outflow section 108 through the outflow hole 105 to the large-capacity silence chamber 104, and the large-volume silence chamber 104 Of the exhaust gas when flowing into the small-volume inflow portion 109 through the inflow hole 106 from
It attenuates the energy of the exhaust gas and reduces the airflow noise.

[0004]

As another means for reducing the air flow noise, it is known to lower the temperature of the exhaust gas to attenuate the energy of the exhaust gas. In general, the exhaust gas is made to contact positively so that the heat of the exhaust gas is sufficiently conducted to the housing and released to the outside air.

However, in the conventional silencer described above, the outflow hole and the inflow hole have a constant diameter and are formed over the entire length of the inner pipe in the axial direction, and most of the exhaust gas flows out and flows through the hole near the partition wall. Exhaust gas is hardly in contact with both ends of the housing, which is a part away from the partition wall, the contact area between the exhaust gas and the housing is reduced, the temperature of the exhaust gas cannot be sufficiently reduced, and the desired amount of airflow noise reduction can be reduced. There is a problem that does not reach.

Accordingly, an object of the present invention is to provide a muffler which solves the above-mentioned problems.

[0007]

Means for Solving the Problems In order to solve the above-mentioned problems, a first invention according to claim 1 has a housing and an inner pipe penetrating through the inside of the housing, wherein the inner pipe is provided. In a muffler having a partition wall provided therein and an outflow hole upstream of the partition wall and an inflow hole formed downstream, the outflow holes are arranged so as to gradually become smaller in diameter as approaching the partition wall, and the inflow hole is adjacent to the partition wall. The muffler is characterized in that the muffler is arranged so that the diameter gradually becomes smaller according to the following formula.

In the present invention, most of the exhaust gas is
The exhaust gas flows out of the large-diameter outflow hole provided on the upstream end side of the exhaust gas into the muffler chamber, and flows in from the large-diameter inflow hole provided on the downstream end side of the exhaust gas. And the exhaust gas contacts the entire inner surface of the housing to lower the temperature of the exhaust gas, so that the air flow noise can be sufficiently reduced.

Further, by providing the outflow hole having a gradually smaller diameter as it approaches the partition wall, the exhaust gas flowing out of the small-diameter outflow hole pushes the exhaust gas which has flowed out of the large-diameter outflow hole toward the inner wall of the housing. Since the contact is made by contact, the temperature of the exhaust gas is sufficiently lowered, and the airflow noise can be further reduced.

According to a second aspect of the present invention, an outflow hole is formed in a range not more than 40% of the entire length of the muffler from the exhaust gas upstream end of the muffler, and the outflow hole is formed from the exhaust gas downstream end of the muffler to the muffler. 2. The silencer according to claim 1, wherein an inflow hole is formed in a range of 25% or less of the entire length.

In the present invention, since the outflow hole and the inflow hole are formed in the above-mentioned range, the exhaust gas surely flows in a wide range from end to end in the housing, and comes into sufficient contact with the housing to form the exhaust gas. The temperature is lowered, and the airflow noise can be reduced more efficiently.

According to a third aspect of the present invention, the partition wall is disposed in a range from 60% to 70% of the entire length of the muffler from the exhaust gas upstream end of the muffler. Is a silencer.

[0013] In the present invention, by disposing the partition wall downstream of the center of the entire length of the muffler, a cushion portion having no outflow hole at the outflow portion is formed, whereby exhaust gas can be removed from the outflow hole through the muffler chamber. The exhaust gas is radially discharged, and is pressed against the inner wall of the housing to make contact therewith, so that the temperature of the exhaust gas is sufficiently lowered and, at the same time, the damping effect of the cushion is added, so that a further reduction in air flow noise can be achieved.

According to a fourth aspect of the present invention, there is provided the muffler according to any one of the first to third aspects, wherein the housing is formed in a bellows shape.

In the present invention, since the housing is formed in a bellows shape, the surface area of the housing is increased, heat exchange is promoted, the temperature of the exhaust gas is sufficiently reduced, and the airflow noise is further reduced. Can be.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described based on the embodiment shown in FIGS.

FIG. 1 shows a first embodiment of the present invention.

The muffler 1 has an exhaust gas upstream end 9 connected to an upstream exhaust pipe (not shown) and an exhaust gas downstream end 10.
The side is connected to a downstream exhaust pipe (not shown) and disposed in the exhaust system of the internal combustion engine.

The housing 2 constituting the silencer 1 is made of a metal cylindrical body and has a cross-sectional shape of a circle, an ellipse, an ellipse or the like, and has both ends, that is, an exhaust gas upstream end 9 and an exhaust gas downstream end 10. Integrated or separate tapered neck 2
a and 2b are formed. The inner pipe 3 is penetrated and held in the housing 2 to form a sound deadening chamber 12.
At the exhaust gas upstream end 9, the neck 2 a and the inner pipe 3 are tightly fitted, and at the exhaust gas downstream end 10, the neck 2 b and the inner pipe 3 are fitted via a wire mesh 11 so as to be slidable. . A partition wall 6 that partitions the inner pipe 3 into an outflow portion 7 from which the exhaust gas G flows out from the inner pipe 3 to the muffler chamber 12 and an inflow portion 8 from which the exhaust gas G flows into the inner pipe 3 from the muffler chamber 12 is formed inside the inner pipe 3. It is provided in. Note that the partition wall 6 may be separate from the inner pipe 3 or may be an integral type obtained by processing the inner pipe itself. The outflow portion 7 is provided with a plurality of outflow holes 4 through which the exhaust gas G flows out from the inner pipe 3 to the silencing chamber 12.
Are provided with a plurality of inflow holes 5 through which the exhaust gas G flows from the silencing chamber 12 to the inner pipe 3.

The outflow holes 4 are formed so as to have a large diameter on the exhaust gas upstream end 9 side and gradually decrease in diameter as approaching the partition 6, and the inflow holes 5 have a large diameter on the exhaust gas downstream end 10 side. It is formed so that the diameter gradually becomes smaller as it approaches the partition 6.

The outlet hole 4 has, for example, a maximum diameter of 10 mm.
And the minimum diameter is 5 mm. The inflow hole 5 has, for example, a maximum diameter of 10 mm and a minimum diameter of 5 mm. In addition, the size of the hole is divided into several groups,
The size may be set to be constant within a group, and the diameter may be gradually reduced for each group. Alternatively, a linear hole array may be provided so that holes having a constant diameter continue on the way.

Exhaust gas G introduced at the exhaust gas upstream end 9
Most of the gas flows out of the large-diameter outflow hole 4 formed on the exhaust gas upstream end 9 side into the silencing chamber 12, flows downstream in the silencing chamber 12, and is formed on the exhaust gas downstream end 10 side. The gas flows through the large-diameter inflow hole 5 and is discharged from the exhaust gas downstream end 10 to the outside of the muffler 1. Therefore, most of the exhaust gas G flows in the housing 2 over a wide range from end to end, and sufficiently contacts the housing 2 to lower the temperature of the exhaust gas and reduce airflow noise.

Further, a part of the exhaust gas G flows out of the small-diameter outflow hole 4 provided on the partition wall 6 side to the muffling chamber 12, and the exhaust gas G flowing out of the large-diameter outflow hole 4 first is transferred to the housing 2. Since the exhaust gas G is brought into contact with the inner wall by being pressed against the inner wall, the temperature of the exhaust gas is sufficiently brought into contact with the housing 2 so that the temperature of the exhaust gas is sufficiently reduced, and the airflow noise can be reduced.

FIG. 2 shows a second embodiment of the present invention.

As shown in FIG. 2, the outlet hole 4 is in the range of 40% or less of the total length _{L 1} of the muffler 1 from the exhaust gas upstream end 9 L
₂ , formed over the inner pipe 3, and the inflow hole 5
It is formed in the inner pipe 3 over a range L ₃ below 25% the total length L ₁ of the muffler 1 from the exhaust gas downstream end 10.

The partition 6 is connected to the muffler 1 from the exhaust gas upstream end 9.
They are arranged in the inner pipe 3 in the range _{L 4} 60% to 70% of the total length _{L 1} of.

Therefore, according to the relationship between L ₂ and L ₄ ,
Can range L ₅ of the outlet hole 4 is not present in the outlet portion 7 of the inner pipe 3, the range is a cushion unit 13.

The outflow holes 4 are divided into three groups, for example, a large-diameter hole 4a, a medium-diameter hole 4b, and a small-diameter hole 4c.
The diameter of the large-diameter hole 4a is 10 mm, and the diameter of the medium-diameter hole 4b is 7 mm.
And the diameter of the small diameter hole 4c is 5 mm.

The arrangement of the outflow holes 4 is such that, for example, as the exhaust gas upstream end 9 approaches the partition 6 side, the large-diameter holes 4
a, four rows of medium diameter holes 4b, and one row of small diameter holes 4c.

The inflow holes 5 are formed in the inflow section 8 by dividing them into, for example, two types of large-diameter holes 5a and medium-diameter holes 5b, and have a constant size in each group. The diameter of the medium diameter hole 4b is 7 mm.

The arrangement of the inflow holes 5 is, for example, four rows of large-diameter holes 5a, four rows of medium-diameter holes 5b, and three rows of medium-diameter holes 5b from the exhaust gas downstream end 10 side to the partition wall 6 side. A column.

The outflow holes 4 and the inflow holes 5 may not be divided into the above-mentioned groups, but may be arranged in such a manner that the diameter gradually decreases as approaching the partition 6 as in the first embodiment.

By forming the outflow hole 4 and the inflow hole 5 over the above-mentioned range, the exhaust gas can be surely transferred to the housing 2.
Flows in a wide area from end to end in the housing 2
And the temperature of the exhaust gas decreases, and the airflow noise can be reduced.

Further, by disposing the downstream side of the center with respect to the total length L ₁ of the partition wall 6 muffler 1, can cushion 13 without outlet hole 4 is present in the outlet portion 7, whereby the exhaust energy And the exhaust gas is caused to flow radially out of the outflow hole 4 into the muffling chamber 12 and pressed against the inner wall of the housing 2 to make contact therewith, so that the temperature of the exhaust gas is sufficiently reduced and the air flow noise can be reduced. .

FIG. 3 shows a third embodiment of the present invention.

As shown in FIG. 3, the housing 2 has a bellows shape 14. By forming the bellows shape 14, the heat exchange area of the housing 2 is increased, and the heat of the exhaust gas is easily radiated to the outside air. Therefore, the temperature of the exhaust gas is sufficiently lowered, and the airflow noise can be reduced. The dimensions such as the height of the bellows and the number of pitches of the bellows are arbitrary, and may be formed only in a certain range of the housing.

FIGS. 4 and 5 show a fourth embodiment of the present invention.

As shown in FIGS. 4 and 5, the housing 2 has a radial cross-sectional shape 15. The radial cross-sectional shape 15 increases the surface area of the housing 2 and makes it easier to release the heat of the exhaust gas to the outside air. Therefore, the temperature of the exhaust gas is sufficiently lowered, and the airflow noise can be reduced.

As shown in FIG. 5, the radial cross section 15 has a four-leaf cross section, but may have three or five or more leaves. Further, it may be spiral in the axial direction.

FIG. 6 shows a fifth embodiment of the present invention.

As shown in FIG. 6, the outflow hole 4 is formed as a louver-shaped hole 16 formed by cutting and raising a part of the inner pipe 3.

The inflow hole 5 may be a louver-shaped hole. Further, although not shown, the outflow hole 4 and the inflow hole 5 may be formed in a long hole or a slit shape.

FIG. 7 shows a sixth embodiment of the present invention.

As shown in FIG. 7, the inner pipe 3 is divided into an outflow pipe 17 and an inflow pipe 18, and an enlarged diameter portion 17 a is formed at the pipe end of the outflow pipe 17.
A partition wall 19 is fixed to the tube end 18a. Enlarged part 1
7a and the pipe end 18a are fitted via a wire mesh 20 so as to be slidable. Alternatively, although not shown, the partition wall 19 may be fixed to the pipe end of the outflow pipe 17, an enlarged diameter portion may be formed at the pipe end of the inflow pipe 18, and the fitting may be performed via the wire mesh 20.

FIG. 8 shows a seventh embodiment of the present invention.

FIG. 8 shows the inner pipe 3 and the partition wall 6 integrated. The closed portion 21 is formed by crushing a predetermined position of the inner pipe 3.

[0047]

As described above, according to the first aspect of the present invention, in the present invention, most of the exhaust gas flows from the large-diameter outflow hole provided on the exhaust gas upstream end side to the noise reduction chamber. Flows out from the large-diameter inflow hole provided on the downstream end side of the exhaust gas, so that the exhaust gas flows widely from end to end in the housing, contacts the entire inner surface of the housing, and lowers the temperature of the exhaust gas. The airflow noise can be sufficiently reduced.

Further, by providing the outflow hole having a gradually smaller diameter as it approaches the partition wall, the exhaust gas flowing out of the small diameter outflow hole pushes the exhaust gas which has flowed out of the large diameter outflow hole to the inner wall of the housing. Since the contact is made by contact, the temperature of the exhaust gas is sufficiently lowered, and the airflow noise can be reduced.

According to the second aspect of the present invention, by forming the outflow hole and the inflow hole over the above range,
Exhaust gas surely flows in a wide range from end to end in the housing, and sufficiently contacts the housing to lower the temperature of the exhaust gas, thereby reducing the airflow noise more efficiently.

According to the third aspect of the present invention, since the partition wall is disposed downstream from the center with respect to the entire length of the muffler, a cushion portion having no outflow hole at the outflow portion can be formed.
Thereby, the exhaust gas is radially discharged from the outflow hole to the muffling chamber and pressed against the inner wall of the housing to be brought into contact with the inner wall of the housing.

According to the fourth aspect of the invention, since the housing is formed in a bellows shape, the surface area of the housing is increased, heat exchange is promoted, the temperature of the exhaust gas is sufficiently reduced, and the airflow noise is further reduced. Can be reduced.

[Brief description of the drawings]

FIG. 1 is a side sectional view showing a first embodiment of the present invention.

FIG. 2 is a side sectional view showing a second embodiment of the present invention.

FIG. 3 is a side sectional view showing a third embodiment of the present invention.

FIG. 4 is a side sectional view showing a fourth embodiment of the present invention.

FIG. 5 is a sectional view taken along line AA in FIG. 4;

FIG. 6 is a side sectional view showing a fifth embodiment of the present invention.

FIG. 7 is a side sectional view showing a sixth embodiment of the present invention.

FIG. 8 is a side sectional view showing a seventh embodiment of the present invention.

FIG. 9 is a side sectional view showing a conventional silencer.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Silencer 2 Housing 3 Inner pipe 4, 4a, 4b, 4c Outflow hole 5, 5a, 5b Inflow hole 6 Partition wall

Claims (4)

[Claims] 1. A housing having a housing and an inner pipe penetrating through the housing, a partition wall is provided in the inner pipe, an outlet hole is formed upstream of the partition wall, and an inlet hole is formed downstream of the partition wall. In the silencer, the outflow holes are arranged so as to gradually decrease in diameter as approaching the partition, and the inflow holes are arranged so as to gradually decrease in diameter as approaching the partition. 2. The outlet hole is formed in a range of 40% or less of the entire length of the muffler from the exhaust gas upstream end of the muffler, and is formed in a range of 25% or less of the total length of the muffler from the exhaust gas downstream end of the muffler. The muffler according to claim 1, wherein the inflow hole is formed. 3. The muffler according to claim 2, wherein the partition wall is arranged in a range from 60% to 70% of the entire length of the muffler from the exhaust gas upstream end of the muffler. 4. The muffler according to claim 1, wherein the housing is formed in a bellows shape.