JP3147612B2 - Branch type exhaust pipe damper - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a branch type exhaust pipe damper for an internal combustion engine such as an automobile.

[0002]

2. Description of the Related Art As a noise source that causes noise outside a vehicle, there is radiated sound generated when an exhaust pipe is excited by vibration of an engine. Since the exhaust pipe is generally formed of a relatively thin steel pipe, it is easy to be excited. The vibration mode includes bending (lateral) vibration with the longitudinal direction of the exhaust pipe as a vibration axis, and an exhaust pipe having a higher frequency than this vibration. Is mainly the crushing vibration in which the cross-sectional shape changes.

Conventionally, as means for suppressing the noise, there has been proposed that an exhaust pipe is a double pipe composed of an inner pipe and an outer pipe closely laminated on the inner pipe. When the exhaust pipe is a double pipe as described above, when the exhaust pipe causes vibration, the inner pipe and the outer pipe vibrate separately, so that friction is generated between the two and the vibration can be suppressed. This double pipe system has a certain effect on the crushing vibration and the torsional vibration, but has a problem that an effective damping effect cannot be obtained especially on the bending vibration which is a problem with noise. Since the exhaust pipe has a double structure, there is a problem that the weight is greatly increased. Further, in the case of an exhaust pipe of a type in which the exhaust pipe is branched into two or more pipes in the middle, since the number of each branch pipe is double, the number of man-hours is increased.

[0004]

Therefore, as a result of various investigations to solve the above-mentioned problems, a cloth-like material 1 consisting of a braided wire in which a steel wire is woven in a twill shape in place of the outer tube is described.
As shown in FIG. 6, for example, by wrapping over two branch pipes 2 of a dual exhaust pipe, and fixing the end 3 to the branch pipe 2 by welding, vibration, especially vibration strength is reduced. It has been found that high resonance can be suppressed efficiently. Reference numeral 4 shown in FIG. 6 represents a fixed portion by welding.

However, in the case of a vibrating body having a high temperature, such as an exhaust pipe, the wire of the cloth-like material is fatigued and stretched due to heat and vibration, and the degree of adhesion to the pipe is reduced, thereby reducing the effect as a damper. A problem has occurred, and it has been found that it is difficult for the means shown in FIG. 6 to maintain the soundproofing effect for a long period of time. The present invention provides a branch-type exhaust pipe damper in which a branch-type exhaust pipe in which two or more branch pipes are combined does not reduce the vibration-suppressing effect of the exhaust pipe even if the cloth-like material is stretched by heat or vibration. It is an object.

[0006]

SUMMARY OF THE INVENTION In order to achieve the above object, a branch type exhaust pipe damper according to the present invention has a structure in which at least two branch pipes are provided in an exhaust pipe of an internal combustion engine branched into a plurality of branch pipes. A cloth-like material obtained by knitting or weaving an elastic metal wire in a state of being elastically deformed so as to approach each other is wound, and the cloth-like material is closely attached to the branch pipe by the elastic restoring force of the branch pipe. is there.

The arrangement of the branch pipes is such that a plurality of branch pipes are arranged in parallel, or a polygonal shape, for example, three branch pipes are bundled in a triangular shape, and four branch pipes are bundled in a quadrangular shape. There are those arranged. The polygonal arrangement may be made in pairs, and a cloth may be attached to each, but the whole is elastically deformed so as to approach the whole from the outside toward the center, and the whole is tied with the cloth. Can be mounted as follows. In addition, one branch pipe may be used in common, two different sets of different branch pipes may be formed, and a different cloth material may be wound around each set.

[0008] The fabric is not particularly limited, and for example, a conventionally known braided wire can be used. In short, the knitting or weaving is performed by bringing the elastic metal wires into close contact with each other, and when the elastic metal wires are excited by the vibration of the exhaust pipe, adjacent wires rub against each other, and the vibration energy of the exhaust pipe is efficiently converted to friction energy. What is necessary is just to convert. The elastic metal wire is not particularly limited, and for example, a steel wire or the like can be used.

Preferably, the cloth-like material is fixed to the exhaust pipe so as not to move due to vibration. Although there is no particular limitation on the fixing method, both ends of the cloth-like material may be welded to the exhaust pipe, both ends may be joined together, and this joint may be welded to the exhaust pipe, and the fray preventing members are attached to the both ends. May be attached, and the fray prevention member may be welded to the exhaust pipe.

It is preferable that the cloth-like material is attached to the entire branch pipe. However, even if it is attached to at least a part of, for example, an exhaust pipe of 1 m, a width of about 30 cm can provide a noise prevention effect.

[0011]

The cloth-like material is flexible and does not resonate with any vibration mode that generates noise in the exhaust pipe. Therefore, the means for attaching the cloth-like material in close contact with the exhaust pipe is characterized in that the elastic metal wire of the cloth-like material is excited in the vibrating exhaust pipe, and between the exhaust pipe and the elastic metal wire, between the adjacent metal wires. Friction is generated between the vibration modes, and the vibration energy can be absorbed as friction energy for any vibration mode to attenuate the vibration.

Further, the means for elastically deforming the cloth-like material so as to bring the branch pipes closer to each other, and for bringing the cloth-like material into close contact with the branch pipe by its restoring force, is characterized in that the elastic metal wire is formed by heat or vibration of the exhaust pipe. Even in the case of stretching due to fatigue, the cloth-like material can be brought into close contact with the exhaust pipe, and acts to maintain the vibration damping effect.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below with reference to the accompanying drawings. The branch type exhaust pipe used in the present embodiment is a dual type exhaust pipe 5 branched into branch pipes 2 arranged in parallel with each other, as shown in FIG. Figures 1-3
The branch-type exhaust pipe damper according to the present embodiment shown in FIG. 1 has a cloth-like material 1 wound over two branch pipes 2.
The symbol α shown in FIG. 3 indicates the clearance when the two branch pipes 2 are in a free state.

In order to attach the cloth-like material 1 to the dual-type exhaust pipe 5, as shown in FIG. 3, a force is first applied so that the branch pipes 2 on the open end side are brought close to each other, and elastically deformed by a deformation allowance γ. In this state, the cloth-like material 1 was wound so as to straddle the two branch pipes 2, and the end 3 was attached to the branch pipe 2 by welding (fixing portion 4). Then, when the above-mentioned force is removed, the branch pipe 2 is in a state where the tension of the cloth-like material 1 and the elastic restoring force of the branch pipe 2 are balanced by the reaction force which is going to restore the original clearance α, that is, the clearance larger than the clearance β. β ′ (FIG. 2) is stable, and the fabric-like material 1 can be closely attached to the branch pipe 2.

As the cloth-like material 1, a braided wire densely knitted in a twill shape using a plurality of wires (elastic metal wires) 6 arranged in parallel with each other as shown in FIG. 4 was used. Although the damper of the present embodiment is formed on a part of the branch pipe 2, it may be formed over the entire surface. Next, the operation of the damper of this embodiment will be described. When the internal combustion engine (not shown) starts and the dual exhaust pipe 5 vibrates, each wire 6 of the cloth-like material 1 that is in close contact with the branch pipe 2 is excited. However, since the vibration mode of the branch pipe 2 is different from the vibration mode of each wire 6, friction occurs between the branch pipe 2 and each wire 6. In this case, since the cloth-like material 1 is excited without resonating with the vibration of the branch pipe 2, it efficiently converts and absorbs vibration energy into heat energy, and exhibits a soundproofing effect. Furthermore, since the elongation force due to the elastic restoring force of the branch pipe 2 acts on the fabric-like material 1, the fabric-like material 1 becomes fatigued by heat and vibration due to long-term use, and is strained even when the wire 6 is stretched. Is not loosened, so that the soundproofing effect can be maintained.

FIG. 5 shows the actual measurement of the vibration state of the exhaust pipe depending on whether or not a bladed wire is used. In the figure, the horizontal axis represents the frequency f, the vertical axis represents the vibration level dB, the solid line represents actual measurement data when a damper is attached, and the dotted line represents actual measurement data without a damper. B represents a crush vibration region. FIG. 5 shows that the exhaust pipe damper of the present invention significantly reduces the peak value, that is, the vibration intensity with respect to the resonance frequency of the exhaust pipe.

[0017]

As described above, the branch-type exhaust pipe damper of the present invention, in a branch-type exhaust pipe of an internal combustion engine, elastically deforms at least two branch pipes so as to approach each other, and the elastic metal is formed by the reaction force. Since the cloth-like material made of the wire is tensioned to be in close contact with the exhaust pipe, even if the cloth-like material expands due to fatigue due to heat and vibration, the cloth-like material is tensioned by the reaction force and radiated from the exhaust pipe. Noise for a long period of time.

[Brief description of the drawings]

FIG. 1 is a perspective view of a branch-type exhaust pipe damper according to a first embodiment of the present invention.

FIG. 2 is a sectional view taken along line II-II of FIG.

FIG. 3 is a cross-sectional view illustrating a process of forming the branch-type exhaust pipe damper of FIG. 1;

FIG. 4 is a knitting pattern diagram of the cloth used in FIG. 1;

FIG. 5 is a graph showing changes in vibration frequency characteristics depending on the presence or absence of a damper shown in FIG. 1;

FIG. 6 is a cross-sectional view for explaining the problem of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Cloth material 2 Branch pipe 3 End part 4 Fixed part 5 Dual exhaust pipe (branch type exhaust pipe) 6 Wire (elastic metal wire) α Clearance β Clearance β 'Clearance γ Deformation allowance

Claims (1)

(57) [Claims] 1. An exhaust pipe of an internal combustion engine branched into a plurality of branch pipes, wherein at least two branch pipes are elastically deformed so as to approach each other, and a fabric-like material obtained by knitting or weaving an elastic metal wire. And a branch-type exhaust pipe damper in which a cloth material is closely attached to the branch pipe by the elastic restoring force of the branch pipe.