JP2551936Y2 - Vehicle exhaust system - Google Patents

Description

[Detailed description of the invention]

[0001]

[Industrial application] This invention is equipped with a catalytic converter
To improved vehicle exhaust systems .

[0002]

2. Description of the Related Art Conventionally, a vehicle exhaust system, for example, has been disclosed in
A muffler as disclosed in Japanese Patent Application Laid-Open No. 124017 is attached, and exhaust noise is silenced by an expansion action of exhaust energy in an expansion chamber in the muffler and a resonance action in a resonance chamber.

[0003] However, the muffler does not exhibit the same silencing effect even if it is mounted at any position in the vehicle exhaust system. Even if the same muffler is installed at a different position, the muffling effect will be different. Figure 5 is a conventional vehicle exhaust system, among the plurality of center frequencies in the exhaust noise is propagated from the engine to the <br/> vehicle exhaust system 1, it is generally perceived by the driver as a resonance Sico Mori sound cabin The sound pressure mode in the vicinity of 100 Hz is shown, in which the horizontal axis represents the length of the vehicle exhaust system 1 and the vertical axis represents the sound pressure ratio.

[0004] Conventionally, axles and professionals are placed under the floor of a vehicle.
Various types of propeller shafts, fuel tanks, catalytic converters, etc.
Since the equipment is attached, the pump in the vehicle exhaust system 1
There are restrictions on the mounting position of the re-muffler 3 and the main muffler 5.
In general, the prima muffler 3 is provided at a substantially intermediate portion of the vehicle exhaust system 1,
The main muffler 5 is usually located downstream of the vehicle exhaust system 1.
Attached to the side. Further, the catalytic converter 7 is
Vehicle exhaust system with high exhaust gas temperature from the viewpoint of gas purification efficiency
1 has been installed on the upstream side.
Installed close to the exhaust manifold from the standpoint of cushioning performance.
A so-called manifold converter is widely used.
And, as shown in FIG.
The position where the re-muffler 3 and the main muffler 5 are mounted, that is,
In the figure, the central part and downstream of the vehicle exhaust system 1 indicated by oblique lines A and B.
The side has a small sound pressure ratio, and the position where the sound pressure ratio is generally high (in the figure,
A hatched portion C) indicates a vehicle exhaust system to which the catalytic converter 7 is attached.
1 upstream . For this reason, even if the prim muffler 3 and the main muffler 5 are attached to such a position where the sound pressure ratio is small , the effect is small . Conventionally, measures such as increasing their capacity have been taken.

[0005]

However, if the capacity of the prim muffler 3 or the main muffler 5 is increased, the cost increases and the weight of the vehicle increases.
These are attached to the vehicle exhaust system 1 as described above.
When installing the vehicle, various devices installed under the floor of the vehicle
Of the vehicle exhaust system 1 with high sound pressure ratio
Attach Prima Muffler 3 and Main Muffler 5 upstream
It was not possible to do it.

[0006] Incidentally, in the Japanese Unexamined Utility Model Publication No. 54-150013, although the catalytic converter provided with expansion chamber therein is disclosed, for such catalytic converters is to provide an expansion chamber around the catalyst, the catalytic converter itself Capacity increases,
Of course, drawbacks such as complicated structure and heavy weight have been pointed out.

The present invention has been devised in view of such circumstances, and a catalyst core conventionally mounted on the upstream side of a vehicle exhaust system.
Focusing on the converter, maximize the capacity of the catalytic converter
The structure and mounting position can be improved without
Accordingly, it is an object of the present invention to provide a vehicle exhaust system that can expect a noise reduction effect of exhaust noise .

[0008]

In order to achieve the object, a vehicle exhaust system according to the present invention has reduced diameter portions at both ends.
On the upstream side and the downstream side in the cylindrical shell (19), respectively,
Catalysts (9, 11) are arranged in series at regular intervals,
A shell (19) is cut between both catalysts (9, 11) at both ends.
It is formed to have the same area and the middle part has a larger cross-sectional area than both ends.
Of the two catalysts (9, 11)
Space (27) formed by the shell and the shell (19)
The body (25) is divided into two chambers, and the cylindrical body (25)
The small number of small holes (35) or resonance tubes (29)
At least one of them is provided, and the cylinder (25) and the shell
The space (27) formed by (19) is used as a sound deadening chamber.
Medium converters (24, 37, 39)
The sound pressure mode of one of the center frequencies
Then, it is mounted at a position where the sound pressure ratio is high .

[0009]

According to the present invention, when exhaust gas flows into the catalytic converter after the start of the engine, harmful components in the exhaust gas are purified by the catalyst. Further, the exhaust energy emitted from the engine, propagates in the space in the catalytic converter that functions as a muffler chamber, At a the muffler chamber, especially
Exhaust noise at a constant frequency is muted.

[0010]

BRIEF DESCRIPTION real施例of the present invention in detail with reference to the accompanying drawings. FIG. 1 shows a vehicle exhaust system according to an embodiment of the present invention.
1 shows a sectional view of a catalytic converter to be mounted , in which 9 is a ceramic oxidation catalyst having a honeycomb-shaped cross section;
Is a ceramic reduction catalyst similarly formed in a honeycomb shape in cross section. Like the conventional catalytic converter, both catalysts 9, 11 are used.
Are arranged at predetermined intervals on the upstream side and the downstream side in a cylindrical shell 19 composed of a pair of half shells 15 and 17 via a metal buffer member 13 fitted to the peripheral edge of each end face. Are arranged in series. An interram mat 21 and a supporter 23 are wound around the outer circumferences of the catalysts 9 and 11, respectively, and the exhaust gas bypasses between the catalysts 9 and 11 and the shell 19 by the interram mat 21. Is prevented.

In the figure , reference numeral 25 denotes an oxidation catalyst 9 and a reduction catalyst 1
1, the cylindrical body 25 is reduced in diameter from the joint between the buffer member 13 on the oxidation catalyst 9 side and the inner periphery of the shell 19 to a diameter sufficiently smaller than the diameter of the shell 19 toward the center of the shell. Frusto-conical tube portion 25a, and a frusto-conical tube portion whose diameter is reduced to a diameter sufficiently smaller than the diameter of the shell 19 from the junction between the buffer member 13 on the reduction catalyst 11 side and the inner periphery of the shell 19 toward the center of the shell. 25b and a small-diameter cylindrical portion 25c that joins the small-diameter open ends of both truncated conical cylindrical portions 25a and 25b to each other. Then, the cylindrical body 25 includes a truncated conical cylindrical portion 25a,
Each end of 25b is joined to the joint between the catalysts 9 and 11 and the shell 19, and is arranged concentrically with the shell 19.

[0012] above the small-diameter cylindrical portion 25c, one end, resonance tube 29 of one of openings inserted in the space 27 formed by the shell 19 and the cylindrical body 25, Such a resonant tube 29 tube By being inserted into the body 25, the space 27 functions as a resonance chamber. In addition, in the figure, 31
Is a mounting flange of the shell 19. And this embodiment
Then, as shown in FIG.
Out of a plurality of center frequencies in the transmitted exhaust noise, 10
The sound pressure mode of the center frequency of 0 Hz is determined, and the vehicle exhaust system 3
3. Look at the position with the highest sound pressure ratio (the shaded area D in FIG. 2).
Emission noise at the frequency of 100 Hz
7. Set the diameter and dimensions of the resonance tube 29 so that
Therefore, the catalytic converter 24 is attached to the hatched portion D in FIG.
It is.

Since the vehicle exhaust system 33 according to the present embodiment is configured as described above, when exhaust gas flows into the catalytic converter 24 when the engine is started, harmful components in the exhaust gas are maintained as in the prior art. Is purified by the oxidation catalyst 9 and the reduction catalyst 11. Further, when the exhaust energy emitted from the engine propagates into the space 27 in the catalytic converter 24, the exhaust noise at a specific frequency (100 Hz in the present embodiment) is silenced. Traditionally, catalytic converters have
The noise reduction effect is not expected.
Although mounted on the upstream side of the exhaust system, this embodiment
Higher sound pressure ratio is located upstream in the exhaust system
In view of the fact that, focusing on this catalytic converter,
Improved structure and mounting position without increasing capacity as much as possible
In addition, the catalytic converter 24 having a sound deadening function
Attached at the highest sound pressure ratio of both exhaust systems 33
It is.

Therefore, according to this embodiment, the conventional catalyst core
A catalytic converter 24 with a simple structure added to the converter
Therefore, the exhaust noise of a specific frequency can be silenced. Naturally
However, such a catalytic converter 24 has a low noise reduction efficiency.
Installed in a small location, minimizing the increase in capacity.
In addition, it is possible to obtain the necessary silencing volume. And like this
Since a noise reduction effect by the catalytic converter 24 can be expected,
It is not necessary to increase the capacities of the prim muffler 3 and the main muffler 5 attached to the downstream side of the vehicle exhaust system 33 as in the related art, so that the vehicle weight and cost do not increase as compared with the related art.

[0015] In the above you施例has to function space 27 as a resonance chamber by inserting the resonance tube 29 to the small-diameter cylindrical portion 25c, as shown in FIG. 3, the peripheral wall of the small-diameter cylindrical portion 25c A plurality of small holes 35 may be formed to allow the space 27 to function as an expansion chamber. Alternatively, as shown in FIG.
Alternatively, the resonance tube 29 may be inserted and a plurality of small holes 35 may be formed in the space 27c so that the space 27 functions as an expansion room together with the resonance room.

In the same manner as in the above embodiment , the catalytic converters 37 and 39 having such a structure are provided with a sound pressure mode of one center frequency among a plurality of center frequencies in the exhaust noise transmitted from the engine to the vehicle exhaust system. And it may be mounted at a position in the vehicle exhaust system where the sound pressure ratio is high. Since the other configurations are the same configuration as the upper you施例, here omitted description thereof, displays drives out identical with those.

In the catalytic converter 37 shown in FIG. 3 , the exhaust energy transmitted into the space 27 is
Exhaust noise of a specific frequency is attenuated by being extended and attenuated within 7.
Further, in the catalytic converter 39 shown in FIG. 4, the exhaust noise is reduced by the action of the resonance chamber and the expansion chamber in the space 27. Therefore, according to these embodiments,
As above you施例, simple structure of the conventional catalytic converter
Specific frequency by the catalytic converters 37 and 39 to which
It has become possible to mitigate a number of exhaust noises. Naturally, these touches
The medium converters 37 and 39 are also installed at positions where the noise reduction efficiency is good.
So that their capacity increase is kept to a minimum.
Required silencing can be obtained. And touch like this
The noise reduction effect of the medium converters 37 and 39 can be expected.
Because, it is not necessary to increase the capacity of conventional as muffler attaches to the downstream side of the vehicle exhaust system 33, due to, nor cause an increase in vehicle weight and cost than conventional.

In each of the above-described embodiments, the oxidation catalyst 9 and the reduction catalyst 11 made of ceramic are used. However, it is needless to say that the catalyst is not limited to such a type.

[0019]

[Effects of the Invention] As described above, the present invention provides a vehicle exhaust system.
The fact that the position with the higher sound pressure ratio is upstream in the system
In consideration of the above, the catalytic converter installed on the upstream side of the vehicle exhaust system
And paying attention to the data, this without increasing as much as possible its capacity
With a noise reduction function, and the catalytic converter
It is installed at a position where the sound pressure ratio of the system is high. Follow
Therefore, according to the present invention, the conventional catalytic converter has a simple structure.
Exhaust of specific frequency by catalytic converter with added structure
Noise can be reduced. Of course, such a catalytic converter
Is installed in a location with good noise reduction efficiency.
The required volume reduction by minimizing the capacity increase of the
Can be. And the noise reduction effect by the catalytic converter
Results can be expected, so that the
It is not necessary to increase the capacity of the muffler
Therefore, there is no increase in vehicle weight or cost compared to the past.
No.

[Brief description of the drawings]

1 is a cross-sectional view of a catalytic converter Ru used in an embodiment of the present invention.

FIG. 2 shows a sound pressure mode of 100 Hz in a vehicle exhaust system ,
This considered showing the attachment position of the catalytic converter or the like that corresponds to
FIG. 4 is a schematic view of a first embodiment of the plan .

FIG. 3 shows a variation of a catalytic converter used in an embodiment of the present invention.
It is a cross-sectional view of Katachirei.

Other catalytic converter used in an embodiment of Figure 4 the present invention
It is sectional drawing of the modification of .

[5] and the sound pressure mode in 100Hz near the vehicle exhaust system mounting position, such as a conventional catalytic converter corresponding thereto
FIG .

[Explanation of symbols]

 Reference Signs List 9 oxidation catalyst 11 reduction catalyst 19 shell 24, 37, 39 catalytic converter 25 cylinder 27 space 29 resonance tube 35 small hole

Claims (1)

(57) [Scope of request for utility model registration] A cylindrical shell (1) having reduced diameter portions at both ends.
The catalysts (9, 11) are respectively provided on the upstream side and the downstream side in 9).
Are arranged in series at regular intervals, and both catalysts (9, 1
1) Both ends have the same cross-sectional area as the shell (19).
A cylindrical body that is formed and has a middle section with a smaller cross-sectional area than both ends
(25), both catalysts (9, 11) and shell (1)
9) and the space (27) formed by the cylindrical body (25).
It is divided into two chambers, and a plurality of
At least one of the small hole (35) and the resonance tube (29)
One of which is formed by a cylinder (25) and a shell (19).
Catalytic converter with the space (27) formed as a sound deadening chamber
(24, 37, 39) is calculated by using multiple center frequencies in the exhaust noise.
Find the sound pressure mode at one of the center frequencies
Vehicle exhaust characterized by being mounted at a position with a high sound pressure ratio
system.