JP2001098922A - Pulsation absorber in vehicle exhaust system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pulsation absorber in a vehicle exhaust system, which can reduce exhaust pulsation without increasing the exhaust resistance and without occurrence of secondary generated sound. SOLUTION: In a pulsation absorber, one 25 of sound suppression chambers in a casing 19 which is connected to an exhaust system through the intermediary of a branch pipe 21 and which is partitioned by a pulsation absorbing member 23 into the two sound suspension chambers, is connected with the branch pipe 21, and the other one 27 of the chambers is filled therein with nonflammable oil. Further, in another aspect, the pulsation absorber 23 is formed of a bellows- like bottomed cylindrical body fitted to the branch pipe with a gap defined between itself and the peripheral wall of the casing 19, and nonflammable oil is filled between the pulsation absorbing member 23 and the casing 19.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a pulsation absorber for a vehicle exhaust system.

[0002]

2. Description of the Related Art In order to reduce exhaust noise during vehicle running,
2. Description of the Related Art Conventionally, a muffler is mounted on a vehicle exhaust system, and an exhaust noise is reduced by an expansion damping action in an expansion chamber of the muffler and a resonance damping action in a resonance chamber (Japanese Patent Publication No. Sho 55-4).
No. 7213). However, the vehicle exhaust system has exhaust pulsation exhausted from the engine, and the conventional muffler has a small rectifying effect of the exhaust pulsation. Therefore, a resonance phenomenon occurs in the vehicle exhaust system due to the effect of the exhaust pulsation. There is a possibility that the ejection noise may be deteriorated.

Therefore, conventionally, measures such as mounting a perforated baffle as a resistor in a vehicle exhaust system or reducing exhaust pulsation by rectifying exhaust pulsation by restricting a muffler pipe have been taken. .

[0004]

However, if a resistor such as a perforated baffle is installed in the vehicle exhaust system, the engine efficiency will deteriorate due to an increase in back pressure caused by the resistor. When the exhaust gas passes through the resistor, the gas flow in the pipe may be disturbed, and a secondary sound (airflow sound) may be generated.

The present invention has been devised in view of the above circumstances, and has a vehicle exhaust system which is simple in mounting and reduces exhaust pulsation without increasing exhaust resistance and generating secondary sound. It is an object of the present invention to provide a pulsation absorber.

[0006]

According to a first aspect of the present invention, there is provided a pulsation absorber for a vehicle exhaust system, which is connected to a vehicle exhaust system via a branch pipe and is defined by a pulsation absorber. The branch pipe communicates with one of the muffle chambers in the casing, and the other muffle chamber in the casing defined by the pulsation absorber is filled with nonflammable oil.

The invention according to claim 2 is based on claim 1
In the pulsation absorber of the vehicle exhaust system described in the above, the pulsation absorber is a bellows-shaped bottomed cylindrical body attached to a branch pipe with a gap between the pulsation absorber and the peripheral wall of the casing. A non-combustible oil is filled between the casing and the peripheral wall of the casing. According to a third aspect of the present invention, in the pulsation absorber for a vehicle exhaust system according to the first or second aspect, the branch pipe is connected to an exhaust pipe of the vehicle exhaust system. According to a fourth aspect of the present invention, in the pulsation absorber for a vehicle exhaust system according to the first or second aspect, the branch pipe is connected to a muffler mounted on the vehicle exhaust system.

According to the pulsation absorbing device of the present invention, when exhaust pulsation is transmitted from the engine to the vehicle exhaust system, the pulsation absorber absorbs the energy of the pulsating pressure to reduce the exhaust pulsation level. I do. The pulsation-absorbed pressure propagates into the silencing chamber filled with nonflammable oil, and is silenced by the resonance action in the silencing chamber.

Further, since the non-combustible oil is filled in the silencing chamber, the non-combustible oil prevents generation of radiated sound from the casing even if the pulsation-absorbed pressure propagates to the silencing chamber. Become.

[0010]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 shows a vehicle exhaust system equipped with a pulsation absorbing device according to the first embodiment of the present invention. In FIG. 1, reference numeral 1 denotes an exhaust manifold, 3 denotes an exhaust pipe, and the exhaust pipe 3 Is a front exhaust 3a flanged to the exhaust manifold 1
, A center exhaust 3b and a rear exhaust 3c, a flexible tube 5 is used as a part of the front exhaust 3a, and a catalytic converter 7 is mounted between the front exhaust 3a and the center exhaust 3b.

The center exhaust 3b is provided with a prima muffler 9, and the center exhaust 3
Exhaust chamber 11 between b and rear exhaust 3c
Is attached, and a main muffler 13 is attached downstream of the rear exhaust 3c.
Exhaust gas and exhaust noise discharged from the engine are transferred from an exhaust manifold 1 through an exhaust pipe 3 to a catalytic converter 7, a pre-muffler 9, and an exhaust chamber 1.
1, and successively flow down and propagate to the main muffler 13.

The present embodiment is characterized in that a pulsation absorbing device 17 is mounted on the front exhaust 3a of the vehicle exhaust system 15 having the same configuration as the conventional one as described above. FIG. 2 shows the details of the pulsation absorbing device 17, and in FIG.
Reference numeral 9 denotes a cylindrical casing connected to the front exhaust 3a via a branch pipe 21, and the branch pipe 21 is attached to a peripheral wall of the front exhaust 3a by welding or screwing.

At the end of the branch pipe 21, a pulsation absorber 23 made of a bellows-like bottomed cylinder is mounted with a gap provided between the branch pipe 21 and the inner wall of the casing 19. The branch pipe 2 is provided inside the casing 19 by the body 23.
The first muffler chamber 25 in the pulsation absorber 23 that communicates with the front exhaust 3a through the first and the second muffler chamber 27 that is sealed between the pulsation absorber and the peripheral wall of the casing. And the non-combustible oil 2
9 are filled.

The pulsation absorbing device 17 sets the damping frequency based on the viscosity of the non-combustible oil 29 and the spring constant of the pulsation absorber 23. In order to reduce the exhaust pulsation with different frequencies, it is possible to reduce the exhaust pulsation at different frequencies by using the same shape and shape.
A casing 19 having the same volume and a branch pipe 21 having the same diameter and the same dimensions can be used.

Since the pulsation absorbing device 17 according to the present embodiment is configured as described above, when the exhaust pulsation discharged from the engine is transmitted to the front exhaust 3a via the exhaust manifold 1, the pulsation pressure is applied to the pulsation. The absorber 23 absorbs the pulsating energy while extending to reduce the exhaust pulsation level, and the pulsated absorbed pressure becomes the second level.
The sound propagates to the muffling chamber 27 and is muffled by the resonance action in the muffling chamber 27.

The non-combustible oil 29 is provided in the sound deadening chamber 27.
Is filled, the non-combustible oil 29 prevents generation of sound radiation from the casing 19 even if the pressure pulsated and absorbed as described above propagates to the second silencing chamber 27. As described above, according to the present embodiment, the pulsation absorber 23 expands with the pulsation pressure of the exhaust pulsation discharged from the engine and absorbs the pulsation energy of the pulsation absorber 23 to reduce the pressure level. The exhaust noise level in the exhaust system 15 is reduced, and the exhaust discharge sound level is reduced.

Since the pulsation absorbing device 17 is a so-called branch type pulsation absorbing device, it does not affect the pressure loss and the secondary sound, and has a simple and compact structure. And its installation is very easy. Furthermore, the sound deadening chamber 27 of the pulsation absorber 17
Since the inside is filled with a non-combustible oil 29, even if the pulsation-absorbed sound wave propagates to the second silencing chamber 27, no radiation sound is generated from the casing 19, and a hole is formed in the pulsation absorber 23. Even when opened, exhaust gas does not leak to the atmosphere due to the presence of the casing 19.

In the above embodiment, the pulsation absorbing device 17 is used.
Is mounted on the front exhaust 3a, but a higher effect can be obtained by mounting the pulsation absorber 17 at a position in the vehicle exhaust system 15 where the pulsation mode is high. And
In the vehicle exhaust system 15, since the high position of the pulsation mode changes for each pulsation frequency, for example, the second embodiment of claims 1 to 3 shown in FIG.
As in the second and fourth embodiments, in the vehicle exhaust system 15, a position where a pulsation mode of a specific frequency at which a pulsation mode aimed at silencing is high is located at the rear exhaust 3 c or the main muffler 13.
1, the shell 13 of the rear exhaust 3c or the main muffler 13 is used instead of the embodiment of FIG.
a shows the viscosity of the non-combustible oil 29 and the pulsation absorber 23, respectively.
If the pulsation absorbers 17-1 and 17-2 with different spring constants are attached, and if the pulsation mode of another specific frequency at which the noise is to be reduced is located at the mounting position of the primulah9, The pulsation absorbing device may be mounted on the shell 9a of the prim muffler 9.

In order to reduce exhaust pulsation of a wide frequency range, the pulsation absorbers 17 and 17-
A plurality of types of pulsation absorbers, such as 1, 17-2, in which the viscosity of the non-combustible oil 29 and the spring constant of the pulsation absorber 23 are set for each frequency, are simultaneously mounted on predetermined positions of the vehicle exhaust system 15, respectively. Good. As described above, according to the present embodiment, by changing the viscosity of the non-combustible oil 29 and the spring constant of the pulsation absorber 23, there is an advantage that it can be used to muffle exhaust pulsation over a wide range.

FIG. 5 shows a pulsation absorbing device according to one embodiment of the present invention. In the drawing, reference numeral 31 denotes a cylindrical casing connected to the front exhaust 3a via a branch pipe 21. The inside of the casing 31 is provided with two noise reduction chambers 3 by a pulsation absorber 33 made of a vibration film such as a rubber film.
5 and 37 are vertically defined, and one muffler chamber 37 is connected to the front exhaust 3a through the branch pipe 21.
And the other silencing chamber 35 is filled with nonflammable oil 29.

The pulsation absorbing device 3 according to the present embodiment
9, the damping frequency is set by the viscosity of the non-combustible oil 29 and the spring constant of the pulsation absorber 33, and the damping frequency is set by the oil viscosity and the spring constant. Thus, in manufacturing a plurality of types of pulsation absorbers, casings 3 having the same shape and the same volume are used.
Branch pipes 21 having the same diameter, the same diameter, and the same size can be used.

The structure of the vehicle exhaust system to which the pulsation absorbing device 39 is attached is the same as that of the above-described embodiment, and a description thereof will be omitted. Since the pulsation absorber 39 according to the present embodiment is configured as described above, when the exhaust pulsation discharged from the engine is transmitted to the front exhaust 3a via the exhaust manifold 1, the pulsation absorber 33 is moved by the pulsation pressure. Absorbs pulsating energy while reducing and expanding as indicated by a two-dot chain line to reduce the pressure level, and the pulsated absorbed pressure propagates to the other muffling chamber 35, where resonance occurs. It will be silenced by the action.

The non-combustible oil 29 is provided in the sound deadening chamber 35.
Is filled, the non-combustible oil 29 prevents the emission of sound from the casing 31 even if the pulsation-absorbed sound propagates to the muffling chamber 35 as described above. As described above, also in the present embodiment, as in the embodiment of FIG. 1, the pulsation absorber 33 expands due to the pulsation pressure of the exhaust pulsation discharged from the engine, absorbs the pulsation energy thereof, and reduces the pressure level. Therefore, the level of exhaust noise in the exhaust system is reduced, and the level of exhaust discharge noise is reduced.

Further, the pulsation absorbing device 39 of the present embodiment is also a branch type pulsation absorbing device, does not affect the pressure loss and the secondary sound, and has a simple and compact structure, so that the existing exhaust gas is not affected. As in the case of the pulsation absorbing device 17 of FIG. 1, the intended purpose can be achieved, for example, it can be installed in a system and its attachment is extremely easy. And
Needless to say, the pulsation absorbing device 39 may be mounted on the rear exhaust 3c, the primula muffler 9, the main muffler 13 and the like instead of the front exhaust 3a or together with the front exhaust 3a.

[0026]

As described above, according to the pulsation absorber according to each of the claims, the pulsation absorber absorbs the exhaust pulsation discharged from the engine and reduces the pressure level. The exhaust noise level in the exhaust system is reduced, and the exhaust discharge sound level is reduced.

Since the pulsation absorbing device is a so-called branch type pulsation absorbing device, it does not affect the pressure loss or the secondary sound, and has a simple and compact structure. And its installation is very easy. Furthermore, according to the pulsation absorbing device according to each claim, by the non-combustible oil filled in the casing,
There is an advantage that it can be used to muffle exhaust pulsation over a wide range by changing the viscosity of the non-combustible oil and the spring constant of the pulsation absorber by preventing generation of noise radiated from the casing.

[Brief description of the drawings]

FIG. 1 is an overall perspective view of a vehicle exhaust system equipped with a pulsation absorber according to a first embodiment of the present invention.

FIG. 2 is a sectional view of the pulsation absorber shown in FIG.

FIG. 3 is a partial perspective view of a vehicle exhaust system equipped with a pulsation absorbing device according to a second embodiment of the present invention.

FIG. 4 is a partial perspective view of a vehicle exhaust system equipped with the pulsation absorbing device according to the first, second and fourth embodiments.

FIG. 5 is a cross-sectional view of a pulsation absorber according to one embodiment of the first and third aspects.

[Explanation of symbols]

 1 Exhaust Manifold 3 Exhaust Pipe 3a Front Exhaust 3b Center Exhaust 3c Rear Exhaust 13 Main Muffler 15 Vehicle Exhaust System 17, 17-1, 17-2, 39 Pulsation Absorber 19, 31 Casing 21 Branch Pipe 23, 33 Pulsation Absorber 25 , 27,35,37 Silencer 29 Non-combustible oil

Claims (4)

[Claims] 1. A muffle chamber (2) in a casing (19, 31) connected to a vehicle exhaust system (15) via a branch pipe (21) and defined by a pulsation absorber (23, 33).
5, 37), the branch pipe (21) communicates therewith, and the casing (19, 3) partitioned by the pulsation absorbers (23, 33).
1) A pulsation absorbing device for a vehicle exhaust system, wherein a non-combustible oil (29) is filled in the other muffling chamber (27, 35). 2. The pulsation absorber (23) includes a casing (1).
The pulsation absorber (23) comprises a bellows-shaped bottomed cylindrical body attached to the branch pipe with a gap provided between the pulsation absorber and the peripheral wall of (9).
Between the inner wall of the casing (19) and the non-combustible oil (2
The pulsation absorbing device for a vehicle exhaust system according to claim 1, wherein (9) is filled. The branch pipe (21) is provided in a vehicle exhaust system (15).
3. The pulsation absorbing device for a vehicle exhaust system according to claim 1, wherein the pulsation absorbing device is connected to an exhaust pipe (3). 4. A branch pipe (21) for a vehicle exhaust system (15).
The pulsation absorber for a vehicle exhaust system according to claim 1 or 2, wherein the pulsation absorber is connected to a muffler (9, 13) mounted on the vehicle.