JPH07310538A - Vibration isolating exhaust pipe - Google Patents

Abstract

PURPOSE:To provide a vibration isolating exhaust pipe which can absorb vibration in the bending direction and in the axial direction without using any interlock or inner blade. CONSTITUTION:This vibration isolating exhaust pipe 10 is constituted of bellows 2 having mountain parts 11 and valley parts 12a, 12b and previously processed by compression, inner pipes 4 provided on both right and left ends of the bellows 2, a blade 6 for regulating the extending range of the bellows 2, and rings 8 provided on both right and left ends. Vibration applied to the pipe 10 in its bending direction is mainly absorbed by the deep valley parts 12a of the bellows 2. Meanwhile, vibration in the axial direction applies a load to the bellows so as to compress the outer circumferential side of the shallow valley parts 12b and the deep valley parts 12a. Consequently, the amplitude of expansion and contraction of the bellows 2 due to vibration in the axial direction is small, and hence there is no possibility of breakdown of the bellows 2 due to fatigue and the like of metal.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vibration isolation exhaust pipe provided in an exhaust system.

[0002]

2. Description of the Related Art An exhaust system of a vehicle is constructed by connecting an exhaust manifold, a catalytic converter, a sub-muffler, a main muffler, etc. assembled to an engine by an exhaust pipe. This exhaust pipe is subject to vibrations caused by engine rolling, pitching, etc., or vibrations on rough roads, which may cause breakage due to resonance of the welded part with the exhaust manifold, etc. or the connection part that fastens these exhaust systems to the body. was there.

In order to eliminate such a problem, it has been known to provide a vibration isolation exhaust pipe between, for example, an exhaust manifold and a converter to isolate the vibration. As a typical example of this vibration isolation exhaust pipe, there is one called a flexible pipe or a flexible pipe, which has an effect of absorbing vibrations due to bending and axial vibrations.

A conventional vibration isolation exhaust pipe 50 shown in FIG. 6 is a bellows 51 having a peak portion and a valley portion.
Inner pipes 52 provided at both left and right ends of the bellows 51, interlocks 53 provided between the inner pipes 52, and inner blades 5 covered by the interlocks 53.
4, a blade 55 that restricts the expansion range of the bellows 51,
And rings 56 provided at both left and right ends.

The interlock 53, as shown in FIG.
A substantially S-shaped band-shaped key body 53a is wound, and adjacent key bodies 53a can be locked to each other. The axial movement range of the interlock 53 is the maximum length shown in FIG.
It is the range from the locked state of (a) to the locked state of FIG. 7 (b) which is the minimum length. The inner blade 54 is covered so as to cover the interlock 53,
The axial movement range of is regulated. That is, assuming that the interlock 53 can move freely between the two locked states shown in FIGS. 7A and 7B, the key body 5 forming the interlock 53 is formed.
Since 3a come into contact with each other and an abnormal noise is generated, the inner blade 54 restricts the moving range of the interlock 53 to prevent the abnormal noise from being generated.

In this vibration isolation exhaust pipe 50, vibrations in the bending and axial directions are basically absorbed by the flexibility of the bellows 51. But,
If the bellows 51 is compressed in the axial direction indefinitely when subjected to a compressive load in the axial direction, the bellows 51 will be damaged due to metal fatigue due to repeated expansion and contraction operations with large amplitude. Therefore, the interlock 53 receives a compressive load in the axial direction to avoid damage to the bellows 51.

[0007]

However, in the conventional exhaust pipe 50 for vibration isolation, it is necessary to mount the interlock 53 and the inner blade 54 for the above-mentioned reason, which increases the vehicle weight and is disadvantageous in improving fuel efficiency. There were some problems. Further, there is a problem that the use of these parts increases the cost and complicates the assembling work.

The present invention has been made in view of the above problems, and an object of the present invention is to provide an exhaust pipe for vibration isolation capable of absorbing vibration in a bending direction and an axial direction without using an interlock or an inner blade.

[0009]

In order to solve the above-mentioned problems, an exhaust pipe for vibration isolation according to claim 1,
Having a mountain portion and a valley portion alternately, the valley portion exists at least two types of shallow, bellows having a location where one or more shallow valley portions are arranged between two adjacent deep valley portions, Inner pipes provided at both ends of the bellows, which come into contact with the bellows within a range from a diameter of a shallow valley portion of the bellows to a diameter of a peak portion of the bellows, and a regulating member which regulates an extension range of the bellows. , Is provided.

As the bellows, a bellows may be used by axially compressing a range from the diameter of the shallow valley portion of the bellows to the diameter of the peak portion of the bellows.

[0011]

According to the vibration isolation exhaust pipe of the first aspect, the vibration in the axial direction is absorbed by the elastic force generated by the gap between the peak and the valley. On the other hand, vibration due to bending is absorbed mainly by the inner peripheral side of the deep valley.

The inner pipe is in contact with the bellows within a range from the diameter of the shallow valley portion of the bellows to the diameter of the peak portion of the bellows. Therefore, the vibration in the axial direction is applied to the bellows via the contact surface, and the peaks, the shallow valleys, and the outer peripheral sides of the deep valleys of the bellows are pressed. Since the mountain portion, the shallow valley portion, and the outer peripheral side of the deep valley portion are arranged with a gap, a kind of elastic body is formed. Therefore, if the elastic force of the gap or the bellows is set according to the load applied by the vibration in the axial direction, the amplitude of the bellows when the vibration in the axial direction is received can be reduced. In other words, the vibration in the axial direction causes the bellows to repeatedly expand and contract with a small amplitude, which can prevent damage to the bellows due to metal fatigue and the like.

As the bellows, a bellows which is compressed in the axial direction in a range from the diameter of the shallow valley portion of the bellows to the diameter of the peak portion of the bellows can be used. Here, the predetermined load means a load equal to or more than the load received by the exhaust pipe due to the vibration of the vehicle. For example, in the case of a passenger car, the load received by the vibration of the vehicle is 100 to 1
Since it is about 50 kg, more load will be applied, but in this case 2 to 2
It is desirable to apply a load of about 3 tons. Even if such a compression process is performed, a springback causes a gap between the peaks and valleys of the bellows, so that the gap can absorb vibration in the axial direction. As described above, since the bellows subjected to the compression treatment is used, even if the bellows are subjected to the vibration in the axial direction, the expansion / contraction operation with a small amplitude is repeated, and the damage of the bellows due to metal fatigue or the like can be prevented. On the other hand, the vibration due to bending is
It is mainly absorbed by the inner peripheral side of the deep valley which is not compressed by the above compression process.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a broken sectional view of an exhaust pipe for vibration isolation according to this embodiment. FIG. 2 is an explanatory view showing a compression process of the bellows.

The vibration isolation exhaust pipe 10 includes a bellows 2 having peaks 11 and valleys 12a and 12b, inner pipes 4 provided at both left and right ends of the bellows 2,
The bellows 2 includes a blade 6 that regulates the extension range of the bellows 2, and rings 8 that are provided at both left and right ends.

The bellows 2 has two kinds of shallow valleys 12a,
12b, deep valley 12a, mountain 11, shallow valley 1
A repeating shape having 2b and the mountain portion 11 as one unit is formed along the axial direction. The bellows 2 has been previously compressed. The compression process is shown below in Figure 2.
It will be explained based on.

That is, as shown in FIG. 2 (a), on the left and right sides of the bellows 2 before compression processing, the outer diameter is equal to or larger than the diameter of the peak portion 11 of the bellows 2 and the inner diameter is a shallow valley portion 12b.
A ring-shaped pressing member 9 having a diameter substantially equal to that of the bellows 2 is arranged, and a predetermined load is applied to the pressing member 9 to compress the bellows 2 in the axial direction. At this time, the deep valley 1 of the bellows 2
The inner peripheral side of 2a, that is, the curved portion is not directly loaded.
When the load is removed, as shown in FIG. 2B, a springback causes a gap between the peak 11 and the valleys 12a and 12b.

The predetermined load applied at this time is set on a case-by-case basis according to the type of vehicle using the vibration isolation exhaust pipe 10 and the type of engine. For example, the load received by the vibration of the vehicle is 100 to 15
In the case of 0 kg, it is preferable to treat with a predetermined load of 2 to 3 t in order to remarkably exhibit the effects. The bellows 2 thus treated is subjected to an axial load of 100 to 150 kg, whereby the vibration isolation exhaust pipe 10 is axially compressed by about 10 to 30 mm (that is, with respect to the axial direction). 30 to 150 N / mm). Further, at this time, the rigidity is increased by compression in the bending direction, and becomes 5 to 15 N / mm. Incidentally, these values are almost the same as those of the vibration isolation exhaust pipe 50 (see FIG. 5) using the conventional interlock. Therefore, the predetermined load applied during the compression process may be set so that the elastic force of the bellows 2 after compression is substantially equal to the load / moving distance of the vibration isolation exhaust pipe 50 using the conventional interlock. .

The outer diameter of the inner pipe 4 is equal to or larger than the diameter of the crest portion 11 of the bellows 2 and the inner diameter thereof is a shallow trough portion 12 of the bellows 2.
It has a ring-shaped pressing surface 13 that substantially matches the diameter of b. Further, the blade 6 is formed in a mesh shape and is attached so as to cover both the inner pipes 4 and the bellows 2.
The blade 6 regulates the maximum length when the bellows 2 extends in the axial direction within a predetermined range.

Next, the above-mentioned vibration isolation exhaust pipe 1
The operation of 0 will be described. FIG. 3 is an explanatory diagram of an exhaust system to which this embodiment is applied. As shown in FIG. 3, the vibration isolation exhaust pipe 10 of this embodiment includes an exhaust manifold 22, which is attached to an engine 21 of a vehicle.
Catalytic converter 23, sub muffler 24, main muffler 2
In the exhaust system 20 of the vehicle constituted by 5, the exhaust system 20 is assembled between the exhaust manifold 22 and the catalytic converter 23. The exhaust system 20 includes a catalytic converter 23.
Are fastened to the body by fastening portions 26 provided between the main muffler 25 and fastening portions 26 provided between the sub muffler 24 and the main muffler 25.

When the exhaust system 20 receives vibrations such as rolling and pitching during driving of the engine 21 or vibrations when traveling on a rough road, the vibrations are absorbed by the vibration isolation exhaust pipe 10. Hereinafter, the vibration components will be described separately for the axial direction and the bending direction.

Vibrations in the bending direction are mainly absorbed by the deep valleys 12a of the bellows 2. Bending rigidity is
It is determined by the curved shape and depth of the deep valley 12a of the bellows 2. That is, the larger the curve radius of the deep valley 12a and the deeper the depth, the lower the bending rigidity.

On the other hand, the vibration in the axial direction is transmitted to the bellows 2 via the pressing surface 13 of the inner pipe 4. The pressing surface 13 has a ring shape whose outer diameter is greater than or equal to the diameter of the crest portion 11 of the bellows 2 and whose inner diameter is substantially the same as the diameter of the shallow trough portion 12b of the bellows 2, so that the crest portion 11 and the shallow trough portion 12b are A load is applied so as to compress the outer peripheral side of the deep valley 12a, and no direct load is applied to the inner peripheral side of the deep valley 12a, that is, the curved portion. At this time, the mountain part 11 and the shallow valley part 12
b, since the outer peripheral side of the deep valley 12a is subjected to the above-described compression processing, depending on the axial load due to the vibration of the vehicle,
The curve shapes of the mountain portion 11 and the shallow valley portion 12b hardly change. The maximum length of the bellows 2 is regulated by the blade 6 within a predetermined range. Therefore, due to the vibration in the axial direction, the bellows 2 causes the peaks 11 and the valleys 12a and 12b to be formed.
Although the bellows 2 expands and contracts by a slight gap, the bellows 2 is not damaged by metal fatigue or the like because the amplitude is small.

Next, the effect of the vibration isolation exhaust pipe 10 of the first embodiment will be described below. As described above, since the vibration isolation exhaust pipe 10 absorbs the vibration of the vehicle, the fastening portion 26 of the exhaust system 20,
There is no risk of the 27, 28 and each weld being broken by the vibration thereof. In the vibration isolation exhaust pipe 10, the range in which the bellows 2 is compressed by the compressive load applied in the axial direction is restricted without using an interlock. Therefore, the interlock and the inner blade are not necessary, and the cost is reduced and the assembling work is simplified.

Next, the second embodiment will be described. Figure 4
[FIG. 7] is a partial cross-sectional view of a second embodiment. The structure of the vibration isolation exhaust pipe 30 of the second embodiment is the same as that of the first embodiment except the shape of the bellows 3. Therefore, the same components as those of the first embodiment are designated by the same reference numerals, and the description thereof will be omitted. Omit it. The bellows 3 of the second embodiment includes two types of deep and shallow troughs 32a and 32b, and a deep trough 32a, a crest 31, a shallow trough 32b, a crest 31, a shallow trough 32b, and a crest 31 as one unit. Is repeated along the axial direction. Further, the bellows 3 has been subjected to the same compression processing as in the first embodiment. The operation and effect of this second embodiment is
Since it is similar to the first embodiment, its explanation is omitted.

Next, a third embodiment will be described. Figure 5
[FIG. 7] is a partial cross-sectional view of a third embodiment. The structure of the vibration isolation exhaust pipe 40 of the third embodiment is the same as that of the first embodiment except the shape of the bellows 5. Therefore, the same components as those of the first embodiment are designated by the same reference numerals, and the description thereof will be omitted. Omit it. The bellows 5 of the third embodiment has a mountain portion 41 and a valley portion 4.
2a, 42b, two types of shallow troughs 42a, 42b
However, one or more shallow troughs 42b are arranged between two adjacent deep troughs 42a. Further, the bellows 3 has been subjected to the same compression processing as in the first embodiment. The operation and effect of this third embodiment is similar to that of the first embodiment, and therefore its explanation is omitted.

Needless to say, the present invention is not limited to the above embodiments and can be implemented in various modes within the technical scope of the present invention. For example, in each of the above-described embodiments, the depth of the trough is two, but the trough may have an intermediate depth.

For the predetermined load in the compression process, the elastic coefficients in the axial and bending directions that the bellows should have are calculated based on the axial and bending loads received by the exhaust pipe of the exhaust system due to vehicle vibration. You may set so that it may become the value of the elastic coefficient. Further, for example, in the third embodiment, the shallow valley portion 4 is provided between two adjacent deep valley portions 42a.
If there is a portion where 2b is not arranged, in the bellows 5 that has been subjected to the compression treatment, the adjacent deep valley portions 42a contact each other and the curved shape changes, which may result in extremely high bending rigidity. Therefore, it is preferable that such a portion should not be formed, but even if there is such a portion, there is no problem because it does not significantly affect the bending rigidity at about one or two portions.

In each of the above-mentioned embodiments, the bellows subjected to the compression treatment are used. However, even when the bellows is not subjected to the compression treatment, the gap between the peaks and the valleys or By setting the elastic force of the bellows, it is possible to reduce the amplitude of the bellows when it receives a vibration in the axial direction, and it is possible to obtain the same effect as that of each of the above embodiments.

[0030]

As described above in detail, according to the vibration isolation exhaust pipe of the present invention, it is possible to absorb the vibration in the bending direction and the axial direction without using an interlock or an inner blade. Therefore, the cost for the interlock and the inner blade can be reduced, and the assembling work can be simplified.

When the bellows are compressed axially in the range from the diameter of the shallow valley of the bellows to the diameter of the peaks of the bellows with a predetermined load, the above effect is remarkably obtained. be able to.

[Brief description of drawings]

FIG. 1 is a broken sectional view of an exhaust pipe for vibration isolation according to a first embodiment.

2A and 2B are explanatory diagrams showing a compression process of the bellows of the first embodiment, FIG. 2A is an explanatory diagram before compression, and FIG.

FIG. 3 is an explanatory diagram of an exhaust system to which the first embodiment is applied.

FIG. 4 is a partial sectional view of a second embodiment.

FIG. 5 is a partial sectional view of a third embodiment.

FIG. 6 is a broken sectional view of a conventional vibration isolation exhaust pipe.

FIG. 7 is an operation explanatory view of an interlock used in a conventional vibration isolation exhaust pipe.

[Explanation of symbols]

2, 3, 5 ... Bellows, 4 ... Inner pipe, 6 ... Blade, 8 ... Ring, 10, 30, 40 ... Exhaust pipe for vibration isolation, 11, 31, 41 ... -Mountains, 12a, 32a, 42a ... Deep valleys, 12b, 32b, 42b ... Shallow valleys, 13 ... Pressing surface, 20 ... Exhaust system,

Claims (2)

[Claims] 1. A portion having alternating peaks and troughs, wherein at least two kinds of troughs exist, and one or more shallow troughs are arranged between two adjacent deep troughs. And a bellows provided at both ends of the bellows, an inner pipe that comes into contact with the bellows within a range from a diameter of a shallow valley portion of the bellows to a diameter of a mountain portion of the bellows, and an extension range of the bellows. An exhaust pipe for vibration isolation, comprising: a regulating member for regulating. 2. The bellows is previously compressed axially in a range from a diameter of a shallow valley portion of the bellows to a diameter of a peak portion of the bellows with a predetermined load. Exhaust pipe for vibration isolation.