JPH07102962A - Damper for exhaust pipe - Google Patents

Abstract

PURPOSE:To provide a damper for an exhaust pipe without lowering vibration restraining effect of the exhaust pipe even by application of heat and vibration. CONSTITUTION:A spring member 5 extending longitudinally is attached to at least a part of an exhaust pipe 7 of an internal combustion engine and a cloth formed matter 1 obtained by knitting or weaving elastic metal wires is attached to both of the exhaust pipe 7 and the spring member 5 to surround then so as to bring the cloth formed matter 1 in tight contact with the exhaust pipe.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an 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 easily excited, and its vibration modes include bending (transverse) vibration with the longitudinal direction of the exhaust pipe as a vibration axis and an exhaust pipe having a frequency higher than this vibration. The crushing vibration whose cross-sectional shape changes is the main one.

As a means for suppressing the noise, conventionally, there has been a proposal that the exhaust pipe is a double pipe composed of an inner pipe and an outer pipe which is closely adhered and laminated on the inner pipe. When the exhaust pipe is a double pipe as described above, when the exhaust pipe vibrates, the inner pipe and the outer pipe vibrate separately, so that friction is generated between them and the vibration can be suppressed. The double pipe system has a certain effect on the crushing vibration and the torsional vibration, but it cannot obtain an effective damping effect particularly on the bending vibration which causes a problem with noise. Since the exhaust pipe has a double structure, there is a problem that the weight is significantly increased.

[0004]

Therefore, as a result of various studies to solve the above problems, as shown in FIG. 8, instead of the outer pipe, a cloth shape made of a braided wire in which a steel wire is braided in a twill shape is formed. Wrap the object 1 around the cylinder 2 and the seam 3
It has been found that vibration, particularly resonance having high vibration intensity, can be efficiently suppressed by welding and fixing to the cylindrical body 2. In addition, the code | symbol 4 shown in FIG. 8 represents the fixed part by welding.

However, in the means shown in FIG. 8, when the tubular body is a member having a high temperature such as an exhaust pipe, the wire of the cloth-like material is stretched by fatigue due to heat and vibration, and the It was found that there is a problem that the degree of adhesion is reduced and the effect as a damper is reduced. An object of the present invention is to provide an exhaust pipe damper that does not reduce the vibration suppressing effect of the exhaust pipe even when the cloth-like material is stretched by heat or vibration.

[0006]

In order to achieve the above object, the exhaust pipe damper of the present invention has a structure in which a spring member extending in the longitudinal direction is attached to at least a part of the exhaust pipe of an internal combustion engine. A cloth-like material obtained by knitting or weaving elastic metal wires around both of the spring member and the spring member is attached, and the cloth-like material is tensioned by the spring member and brought into close contact with the exhaust pipe.

The cloth-like material is not particularly limited and, for example, a conventionally known braided wire can be used. The point is that the elastic metal wires are knitted or woven in 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 into friction energy. Anything that can be converted will do. The elastic metal wire is not particularly limited, but a steel wire or the like can be used.

The cloth-like material is preferably fixed to the exhaust pipe so as not to move due to vibration. The fixing method is not particularly limited, but both ends of the cloth-like material may be welded to the exhaust pipe, respectively, both ends may be joined together, and the joint may be welded to the exhaust pipe. Alternatively, the anti-ravel member may be welded to the exhaust pipe.

The cloth-like material is preferably attached to the entire exhaust pipe, but the noise-preventing effect can be exhibited even if it is attached to at least a part, for example, an exhaust pipe of 1 m in a width of about 30 cm.

[0010]

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

Further, the means for tensioning the cloth-like material by the spring member to bring it into close contact with the exhaust pipe allows the cloth-like material to be exhausted even when the elastic metal wire is stretched due to heat or vibration of the exhaust pipe. It is brought into close contact with and acts so as to maintain the vibration damping effect.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to the accompanying drawings. In the first embodiment shown in FIGS. 1 to 4, the arm portion 6 of the spring member 5 in which the leaf spring is bent in two stages as shown in FIGS. 1 and 3 is arranged in parallel apart from the exhaust pipe 7. The end portion 8 was welded to the exhaust pipe 7, the cloth-like material 1 was wound over the arm portion 6 and the exhaust pipe 7, and the seam 3 was welded to the exhaust pipe 7 to form a damper. In order to bring the cloth-like material 1 into close contact with the exhaust pipe 7 by the spring member 5, the cloth-like material 1 is attached in advance as shown by the chain double-dashed line in FIG. 3, and the cloth-like material 1 is attached by the elastic restoring force of the spring member 5. You just need to make 1 nervous. Since the other parts are configured in the same manner as the damper described in FIG. 8, the same members are designated by the same reference numerals and the description thereof will be omitted.

As the cloth-like material 1, a braided wire is used in which a plurality of wires 9 arranged in parallel with each other as shown in FIG. Although the damper of the first embodiment is formed on a part of the exhaust pipe 7, it may be formed on the entire surface. Next, the operation of the damper of the first embodiment will be described. When an internal combustion engine (not shown) is started and the exhaust pipe vibrates, each wire 9 of the cloth-like object 1 that is in close contact with the exhaust pipe 7 is excited. However, since the vibration mode of the exhaust pipe 7 and the vibration mode of each wire 9 are different,
Friction occurs between the exhaust pipe 7 and each wire 9.
In this case, since the cloth-like material 1 is excited without resonating with the vibration of the exhaust pipe 7, the vibration energy is efficiently converted and absorbed into heat energy, and the soundproof effect is exhibited. Further, since the stretching force due to the elastic restoring force of the spring member 5 acts on the cloth-like material 1, even if the cloth-like material 1 is fatigued by heat or vibration due to long-term use and the wire 9 is stretched, Since the tension is not loosened, 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 the braided wire is used. In the figure, the horizontal axis is the frequency f, the vertical axis is the vibration level dB, the solid line is the measured data when a damper is attached, the dotted line is the measured data when no damper is used, and A is the bending vibration range. B represents the collapse vibration range. From FIG. 5, it can be seen that the exhaust pipe damper of the present invention remarkably reduces the vibration intensity with respect to the peak value, that is, the resonance frequency of the exhaust pipe.

The damper according to the second embodiment shown in FIGS. 6 and 7 has a uniform tension force in the longitudinal direction of the cloth-like material 1. That is, as shown in FIG. 6, the spring member 5 of Example 2 was formed into a shape having a semicircular cross section and rounded ends, and the central portion was welded to the exhaust pipe 7 (fixed portion 4). It is a thing. To attach the fabric-like material 1, the spring member 5
7 may be bent as shown by the chain double-dashed line in FIG. 7 to attach the fabric-like object 1, and the elastic restoring force of the spring member 5 may be used to tension the same. The spring member 5 can exert the same tension over the entire length of the cloth-like material 1. It was confirmed that the damper of Example 2 also exhibited the same excellent effects as in Example 1.

[0016]

As described above, in the exhaust pipe damper of the present invention, the cloth member made of the elastic metal wire is tensioned and brought into close contact with the exhaust pipe by the spring member attached to the exhaust pipe of the internal combustion engine. Even if the cloth-like material is stretched due to fatigue due to heat and vibration, the elastic force of the spring member causes the cloth-like material to be strained, and noise emitted from the exhaust pipe can be prevented over a long period of time.

[Brief description of drawings]

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

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

FIG. 3 is a side view of FIG.

FIG. 4 is a knitting pattern diagram of the cloth-like material used in FIG. 1.

5 is a graph showing a change in vibration frequency characteristic depending on the presence or absence of the damper shown in FIG.

FIG. 6 is a cross-sectional view of an exhaust pipe damper according to a second embodiment of the present invention.

FIG. 7 is an enlarged front view of the spring member shown in FIG.

FIG. 8 is a transverse cross-sectional view for explaining the problem of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Cloth-like object 2 Cylindrical body 3 Seam 4 Fixing part 5 Spring member 6 Arm part 7 Exhaust pipe 8 End part 9 Wire (elastic metal wire)

Claims (1)

[Claims] 1. At least a part of an exhaust pipe of an internal combustion engine,
A spring member extending in the longitudinal direction is attached, a cloth-like material obtained by knitting or weaving elastic metal wires is attached to surround both the exhaust pipe and the spring member, and the cloth-like material is tensioned by the spring member and exhausted. Exhaust pipe damper closely attached to the pipe.