JP2000179323A - Automobile exhaust muffler - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve reduction in both exhaust noise and exhaust loss at low and high engine speeds, by providing a first tail tube for discharging an exhaust gas while a valve is closed and a second tail tube for discharging an exhaust gas together with the first tail tube while the valve is opened, and disposing the first and second tail tubes adjacent to each other, wherein each of the first and second tail tubes has a semicircular cross-section. SOLUTION: In a low engine-speed range having a low exhaust flow-rate, a spring force biasing a switching valve 9 in a closing direction is larger than a pressure in a first pass tube 7, whereby the switching valve 9 is closed. Therefore, an exhaust gas within a first volume chamber 3 is discharged to the atmosphere only through a first tail tube 6. As a result, exhaust noise in a low frequency range, which is a main noise component in the low engine-speed range, is sufficiently muffled. In intermediate and high engine-speed ranges having a high exhaust flow-rate, the switching valve 9 is opened, whereby the exhaust gas in the first chamber 3 and a second volume chamber 4 is discharged to the atmosphere through the first tail tube 6 and the second tail tube 8 each having a semicircular cross-section. Accordingly, exhaust loss and flow noise can be significantly reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for reducing noise generated from an exhaust system of an automobile or the like.

[0002]

2. Description of the Related Art Conventional exhaust silencers for automobiles include:
For example, there is one disclosed in JP-A-9-242525. This is provided in the muffler by opening and closing a valve or a valve according to the exhaust gas pressure for the purpose of reducing exhaust noise at low rotation, reducing exhaust noise at high rotation, and reducing exhaust loss. A plurality of flow paths are switched.

[0003]

However, since the conventional example has a dual tail tube structure, when a muffler having, for example, a fixed type single tail tube structure must be separately provided in a vehicle to which the muffler is to be mounted, A new bumper is required. Conversely, even if two tail tubes are brought close enough to share a bumper, each tail tube must be supported by a baffle in the muffler, making production extremely difficult in consideration of sealing properties and the like. I will. Further, since the muffler cross section is small in the small displacement vehicle, there is no space for housing the valve unit. Also, since the two tail tubes are separated, it is possible to maximize the interference effect by interfering with the opposite phase sounds coming out of the two tail tubes in the process from valve fully closing to fully opening. There was a problem that it was difficult. The present invention has been made in view of such a conventional problem, and has a first tail tube for discharging exhaust gas when the valve is closed and a second tail tube for discharging additional exhaust gas when the valve is opened. It is an object of the present invention to solve the above-mentioned problem by making the tail tubes adjacent to each other in a half-moon shape.

[0004]

According to a first aspect of the present invention, an exhaust tube for guiding exhaust gas from an engine into a muffler is provided. A first volume chamber in the muffler that is open, a first tail tube that discharges exhaust gas from the first volume chamber to the atmosphere, a plurality of volume chambers partitioned in the muffler, A plurality of pass tubes for sequentially guiding exhaust gas to the plurality of volume chambers, and a second tail communicating with the most downstream volume chamber among the plurality of volume chambers and adjacent to the first tail tube. The pressure in the first volume chamber is increased to a predetermined pressure by providing a tube, an on-off valve disposed downstream of the pass tube, and an urging member that applies an urging force to the on-off valve. When the lower discharging the exhaust gas only from the first tail tube, said at a predetermined pressure or more first
The exhaust gas is discharged from the second tail tube in addition to the tail tube.

According to a second aspect of the present invention, in the vehicle exhaust silencer according to the first aspect, a cross section of each of the first tail tube and the second tail tube has a half-moon shape. According to a third aspect of the present invention, in the vehicle exhaust silencer according to the second aspect, the first tail tube and the second tail tube are integrally formed.
Alternatively, they are formed separately from each other and then combined, or formed by inserting a partition into a tubular member. According to a fourth aspect of the present invention, in the exhaust muffler for a vehicle according to the third aspect, the first tail tube and the second tail tube are curved on the side open to the atmosphere. In the invention according to claim 5, claim 3
The exhaust muffler for a vehicle according to the present invention, characterized in that the first tail tube and the second tail tube are offset on the atmosphere opening side. According to a sixth aspect of the present invention, in the exhaust muffler for an automobile according to the third to fifth aspects, an open side of the first tail tube or the second tail tube to the atmosphere is cut obliquely. According to a seventh aspect of the present invention, in the exhaust muffler for an automobile according to the third to sixth aspects, a sectional area ratio between the first tail tube and the second tail tube is made equal or unequal. According to an eighth aspect of the present invention, in the vehicle exhaust silencer according to any of the third to seventh aspects, a small hole is provided in a part of the first tail tube or the second tail tube. According to a ninth aspect of the present invention, in the vehicle exhaust silencer according to any one of the third to eighth aspects, a communication pipe for communicating the first volume chamber and the plurality of volume chambers is provided in addition to the pass tube. And According to a tenth aspect of the present invention, in the exhaust muffler for a vehicle according to the third to ninth aspects,
The inlet tube and the pass tube communicating with the first volume chamber are integrally formed, and a porous portion is provided on the way.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. (Embodiment 1) FIG. 1 is a diagram showing Embodiment 1 of the present invention. An inlet for introducing exhaust gas from an engine (not shown) into the first volume chamber 3 in the muffler 1 including the first volume chamber 3, the second volume chamber 4, and the third volume chamber 10 partitioned by the baffle 2. The tube 5 is open. Further, a first tail tube 6 is connected to the first volume chamber 3 to release the introduced exhaust gas to the atmosphere.
Further, the second volume chamber 4 is also connected to the first volume through the first path tube 7.
The second volume chamber 4 is connected to the third volume chamber 10 via a second pass tube 11. A second tail tube 8 that is open to the atmosphere is connected to the third volume chamber 10. The cross section of the first tail tube 6 and the second tail tube 8 has a half-moon shape as shown in FIG. 2, and those manufactured separately are connected by welding or the like. At the downstream end of the second pass tube 11, an open / close valve 9 urged by a spring (not shown) is provided.

Next, the operation and effect of this embodiment will be described.
When the exhaust gas flow rate is low (low engine speed range),
Since the urging force of the spring is greater than the pressure in the first pass tube 7, the opening / closing valve 9 is closed and the first volume chamber 3
The exhaust gas inside is exhausted to the atmosphere only from the first tail tube 6. As a result, the expansion ratio of the first tail tube 6 to the first volume chamber 3 is ensured, so that exhaust noise in a low frequency range, which is a main component in a low engine speed range, can be sufficiently suppressed.

When the flow rate of the exhaust gas is large (in the middle / high engine speed range), the pressure in the first pass tube 7 exceeds the biasing force of the spring, so that the opening / closing valve 9 is opened and the first volume chamber is opened. The exhaust gas in 3 is discharged from the first tail tube 6 to the atmosphere, and passes through the first pass tube 7, the second volume chamber 4, the second pass tube 11, and the third volume chamber 10 to the second tail tube. 8 will also be released to the atmosphere. As a result, exhaust loss and airflow noise can be significantly reduced.

In the process of opening / closing valve 9 from full opening to full opening, first tail tube 6 and second tail tube 8
Exhaust sound discharged from the muffler 1 has an opposite phase relationship and interferes with each other, so that the exhaust sound can be further reduced. However, in the muffler 1, the first tail tube 6 and the second tail tube 8 are arranged adjacent to each other. Since the degree of the interference is larger than that of the conventional one, the exhaust noise can be further reduced.

Further, since the first tail tube 6 and the second tail tube 8 are connected, these tubes can be reliably supported inside the muffler even by a conventional manufacturing method. Therefore, the muffler 1 can be mounted on a vehicle equipped with a single tail tube muffler without changing the bumper. Conventionally, the tail tube is dispersed in the muffler cross section, but in this embodiment, since the tail tube is concentrated on a part of the cross section, the valve unit is installed even if the muffler cross section is small like a small displacement vehicle. A sufficient space can be secured.

(Second Embodiment) FIG. 3 is a diagram showing a second embodiment. In the present embodiment, the first tail tube 6 and the second tail tube 8 of the first embodiment are integrally formed from a single iron plate. By doing this,
Since only half the plate material is required to separate the first tail tube 6 and the second tail tube 8, the weight and cost can be reduced.

(Third Embodiment) FIG. 4 is a diagram showing a third embodiment. In the present embodiment, the cross-sectional area of the first tail tube 6 of the first embodiment is smaller than the cross-sectional area of the second tail tube 8. By doing this,
When the on-off valve 9 is closed, the expansion ratio of the first tail tube 6 to the first volume chamber 3 can be further increased, so that the exhaust noise can be further reduced. Opening / closing valve 9
Opening / closing operation is determined by the pressure loss ratio between the path on the first tail tube 6 side and the path on the second tail tube 8 side. Fine adjustment can be performed by changing this cross-sectional area ratio. The degree of freedom in design can be increased (in the past, there were only combinations of several types of pipe diameters).

(Fourth Embodiment) FIG. 5 is a diagram showing a fourth embodiment. In the present embodiment, the inlet tube 5 and the first pass tube 7 of the first embodiment are formed as one tube, and the porous portion 12 is provided in the middle thereof. By doing so, particularly when the on-off valve 9 is opened, generation of airflow noise can be suppressed, and exhaust loss can be reduced.

(Fifth Embodiment) FIG. 6 is a diagram showing a fifth embodiment. In the present embodiment, a small hole 13 is provided in the first tail tube 6 of the first embodiment. By doing so, resonance generated in the first tail tube 6 can be suppressed.
(Sixth Embodiment) FIG. 7 is a diagram showing a sixth embodiment. In the present embodiment, the first volume chamber 3 and the second volume chamber 4 of the first embodiment are connected by a communication pipe 14 in addition to the first pass tube 7. By doing so, when the on-off valve 9 is closed, the degree of freedom in designing the silencing frequency of the resonance element constituted by the first pass tube 7 and the second volume chamber 4 can be increased.

(Seventh Embodiment) FIG. 8 is a diagram showing a seventh embodiment. In the present embodiment, the first tail tube 6 and the second tail tube 8 of the first embodiment are curved on the air opening side. By doing so, the discharge direction of the exhaust gas flow can be freely set, so that the degree of freedom in design can be increased.

(Eighth Embodiment) FIG. 9 is a diagram showing an eighth embodiment. In the first embodiment, when the on-off valve 9 is closed, the second exhaust sound is discharged from the first tail tube 6 side.
The resonance system constituted by the tail tube 8 and the third volume chamber 10 may be excited, and the exhaust sound may be deteriorated.

In the present embodiment, the air release side of the second tail tube 8 of the first embodiment is offset from the air release side of the first tail tube 6 to the muffler 1 side. This makes it difficult for the resonance system on the second tail tube 8 side to be excited, thereby preventing deterioration of exhaust sound.

(Embodiment 9) FIG.
FIG.

In this embodiment, the first tail tube 6 of the first embodiment is cut obliquely on the open side to the atmosphere. By doing so, the exhaust sound of the first tail tube 6 causes the second
The resonance system on the side of the tail tube 8 is less likely to be excited, and exhaust noise can be prevented from being deteriorated.

(Embodiment 10) FIG. 11 shows a tenth embodiment. This embodiment is similar to the third embodiment.
The first tail tube 6 and the second tail tube 8 are curved on the side open to the atmosphere, and the second tail tube 8 side is cut obliquely. When the opening / closing valve 9 is opened, the exhaust flow rate of the second tail tube 8 is larger than that of the first tail tube 6, but the flow velocity vector of the second tail tube 8 is cut like the first tail tube 6 because the second tail tube 8 is cut diagonally. Since it does not bend significantly, in this embodiment, in addition to the effects of the third, seventh, and ninth embodiments, deterioration of airflow noise can be prevented.

[0021]

As described above, according to the first aspect of the present invention, the inlet tube for guiding the exhaust gas from the engine into the muffler, the first volume chamber in the muffler where the inlet tube opens, A first tail tube for discharging exhaust gas from the first volume chamber to the atmosphere, a plurality of volume chambers partitioned in the muffler, and an exhaust gas from the first volume chamber sequentially leading to the plurality of volume chambers. A plurality of pass tubes, a second tail tube communicating with the most downstream volume chamber of the plurality of volume chambers and adjacent to the first tail tube, and disposed downstream of the pass tube. And a biasing body for applying a biasing force to the open / close valve, so that when the pressure in the first volume chamber is equal to or lower than a predetermined pressure, the exhaust is discharged only from the first tail tube. Gas emissions, the predetermined pressure or more and also for discharging exhaust gas from the addition to the first tail tube second tail tube, further, claim 2
According to the invention described in the above, in the automobile exhaust silencer according to the first aspect, since the cross sections of the first tail tube and the second tail tube have a half-moon shape, it is difficult to mount the conventional tail tube type muffler. This muffler can be mounted on vehicles with a single tail tube muffler without changing the bumper. Also,
Even if the muffler cross section is small like a small displacement vehicle, a sufficient space for housing the valve unit can be ensured. Further, the interference effect can be maximized as compared with the conventional one.

According to a third aspect of the present invention, in the vehicle exhaust silencer according to the second aspect, the first tail tube and the second tail tube are integrally molded or formed separately from each other and then joined together. Since the partition is inserted or formed into a tubular member, the weight and cost can be reduced. According to a fourth aspect of the present invention, in the vehicle exhaust silencer according to the third aspect,
Since the open side of the first tail tube and the second tail tube is opened, the degree of freedom in design can be increased. According to a fifth aspect of the present invention, in the vehicle exhaust silencer according to the third aspect, the first tail tube and the second tail tube are offset from the open side to the atmosphere, so that the resonance system on the second tail tube side is excited. This makes it difficult to reduce exhaust noise. According to the sixth aspect of the present invention, in the vehicle exhaust silencer according to any one of the third to fifth aspects, the first tail tube or the second tail tube is obliquely cut on the open-to-atmosphere side, so that the resonance system on the tail tube side is reduced. Excitation is less likely to occur, and deterioration of exhaust noise can be prevented. According to the seventh aspect of the present invention, in the exhaust muffler for an automobile according to the third to sixth aspects, since the sectional area ratio of the first tail tube and the second tail tube is made equal or unequal, when the opening and closing valve is closed, The exhaust noise can be further reduced. Further, the degree of freedom in designing the entire system can be expanded. According to an eighth aspect of the present invention, in the exhaust muffler for an automobile according to the third to seventh aspects, a small hole is provided in a part of the first tail tube or the second tail tube. Resonance can be suppressed. According to the ninth aspect of the present invention, in the vehicle exhaust silencer according to the third to eighth aspects, a communication pipe communicating the first volume chamber and the plurality of volume chambers is provided in addition to the pass tube. When closed, the degree of freedom in designing the silencing frequency of the resonance element constituted by the first pass tube and the second volume chamber can be increased. According to a tenth aspect of the present invention, in the vehicle exhaust silencer according to the third to ninth aspects, the inlet tube and the pass tube communicating with the first volume chamber are integrally formed, and a porous portion is provided in the middle. Thus, it is possible to suppress airflow noise and reduce exhaust loss.

[Brief description of the drawings]

FIG. 1 is a diagram showing a first embodiment of the present invention.

FIG. 2 is a sectional view of the tail tube shown in FIG.

FIG. 3 is a sectional view of a tail tube according to a second embodiment.

FIG. 4 is a diagram showing a third embodiment.

FIG. 5 is a diagram showing a fourth embodiment.

FIG. 6 is a diagram showing a fifth embodiment.

FIG. 7 is a diagram showing a sixth embodiment.

FIG. 8 is a diagram showing a seventh embodiment.

FIG. 9 is a diagram showing an eighth embodiment.

FIG. 10 shows a ninth embodiment.

FIG. 11 shows a tenth embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Muffler 2 Baffle 3 1st volume room 4 2nd volume room 5 Inlet tube 6 1st tail tube 7 1st pass tube 8 2nd tail tube 9 Opening-and-closing valve 10 3rd volume room 11 2nd pass tube 12 Porous part 13 Small Hole 14 Communication pipe

Claims (10)

[Claims] 1. An inlet tube for guiding exhaust gas from an engine into a muffler, a first volume chamber in the muffler where the inlet tube opens, and a first exhaust gas from the first volume chamber to the atmosphere. A tail tube; a plurality of volume chambers partitioned in the muffler; a plurality of pass tubes for sequentially leading exhaust gas from the first volume chamber to the plurality of volume chambers; A second chamber adjacent to the first tail tube and communicating with the most downstream volume chamber.
A tail tube, an on-off valve disposed downstream of the pass tube, and an urging body for applying an urging force to the on-off valve, wherein the pressure in the first volume chamber is equal to or lower than a predetermined pressure. An exhaust muffler for automobiles, wherein exhaust gas is exhausted only from the first tail tube, and exhaust gas is exhausted from the second tail tube in addition to the first tail tube when the pressure exceeds a predetermined pressure. 2. The first tail tube and the second tail tube.
2. The exhaust muffler for an automobile according to claim 1, wherein a cross section of the tail tube has a half-moon shape. 3. The method according to claim 1, wherein the first tail tube and the second tail tube are integrally formed, or formed separately from each other and then combined, or formed by inserting a partition into a tubular one. 3. The exhaust muffler for an automobile according to claim 2, wherein: 4. The first tail tube and the second tail tube.
4. An exhaust muffler for an automobile according to claim 3, wherein the tail tube has a curved side on the side open to the atmosphere. 5. The first tail tube and the second tail tube.
4. An exhaust muffler for an automobile according to claim 3, wherein the tail tube has an offset side to the atmosphere. 6. The first tail tube or the second tail tube.
6. The vehicle exhaust silencer according to claim 3, wherein the tail tube has an obliquely open side on the atmosphere. 7. The vehicle exhaust silencer according to claim 3, wherein a sectional area ratio of the first tail tube and the second tail tube is made equal or unequal. 8. The first tail tube or the second tail tube.
8. The vehicle exhaust silencer according to claim 3, wherein a small hole is provided in a part of the tail tube. 9. The vehicle exhaust silencer according to claim 3, further comprising a communication pipe communicating between said first volume chamber and said plurality of volume chambers, in addition to said pass tube. 10. The exhaust muffler for an automobile according to claim 3, wherein the inlet tube and the pass tube communicating with the first volume chamber are integrally formed, and a porous portion is provided in the middle thereof. .