JP2004170531A - Noise reduction member - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a noise reduction member for simultaneously realizing heat radiation and noise reduction, and to provide a head cover for reducing engine noise without increasing weight and a manufacturing cost by enabling heat radiation from a cylinder head particularly. <P>SOLUTION: The noise reduction member (for instance, the head cover 101) covering at least a part (for instance, a cylinder head 102) of a sound source (for instance, a vehicle engine) comprises a porous material, and at least one through hole penetrated to a reverse side space (for instance, the engine outside) from the side of the sound source is provided. Furthermore, the material and the shape are set so that a first sound wave A generated from the sound source and passing the member and a second wave B generated from the sound source and passing through a hole are mutually interfered in the reverse side space. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention generally relates to a member for reducing noise, and more particularly to a head cover for reducing noise generated from an engine in a vehicle.
[0002]
[Prior art]
In a vehicle engine, a cylinder head 102 portion of the engine body is generally covered with a head cover 101 to maintain airtightness, as schematically shown in FIG.
[0003]
The head cover 101 is attached to the cylinder head 102 via a gasket (not shown).
[0004]
For example, as schematically shown in FIG. 2, a sound insulating material (or sound absorbing material) 201 may be attached to the back surface of the conventional head cover 101 (the inner wall on the engine side) in order to reduce noise generated from the engine. Many.
[0005]
In addition, an engine cover structure for sound insulation and engine cooling without using a sound insulating material has been proposed (for example, see Patent Document 1).
[0006]
[Patent Document 1]
JP-A-11-30393 (FIG. 1)
[0007]
[Problems to be solved by the invention]
However, in the conventional head cover structure provided with the above-described sound insulating material, a sound insulating material having a sufficient thickness must be attached in order to sufficiently reduce noise, which causes an increase in weight and manufacturing cost. Was.
[0008]
In addition, since the head cover has a closed structure, heat of the engine cannot be released from the cylinder head portion.
[0009]
Furthermore, the engine cover structure described in Patent Document 1 cannot sufficiently prevent noise from leaking from an opening opened for cooling the engine.
[0010]
SUMMARY OF THE INVENTION The present invention has been made to solve such a problem, and it is possible to dissipate heat from a cylinder head portion and reduce engine noise without increasing weight and manufacturing cost. Its primary purpose is to provide a cover.
[0011]
[Means for Solving the Problems]
One embodiment of the present invention is a noise reduction member (for example, a head cover) that covers at least a part (for example, a cylinder head) of a sound source (for example, a vehicle engine), which is made of a porous material, And at least one through-hole penetrating from the side to the space on the opposite side (for example, the outside of the engine), a first sound wave A emitted from the sound source and transmitted through the member, and the hole emitted from the sound source and Is a noise reduction member whose material and shape are set such that the second sound wave B passing through the second space B interferes with each other in the space on the opposite side.
[0012]
In this embodiment, the sound speed of the sound wave A is reduced by transmitting through the head cover, and the material of the head cover (for example, density, sound wave) is set so as to have a phase difference of 180 ° with the phase of the sound wave B which is a direct wave. It is preferable to set the transmission coefficient and the like and the shape (for example, the thickness, the number and the shape of the through holes, and the like). This is because, in this case, the sound waves A and B cancel each other, so that the noise generated from the engine is reduced.
[0013]
Therefore, according to one aspect, there is provided a head cover capable of reducing engine noise without increasing weight and manufacturing cost.
[0014]
In addition, since the head cover according to the above-described embodiment is provided with a through hole and is not a closed structure, it is possible to reduce engine noise and release heat from the cylinder head.
[0015]
As will be apparent to those skilled in the art, in the present invention, the sound source that generates the noise to be reduced is not limited to the vehicle engine, and thus the present invention is not limited to the head cover.
[0016]
That is, the present invention can be applied to any sound source not only in a vehicle engine but also in any equipment as long as the cover member covers at least a part of the sound source. However, when applied to a vehicle engine, it can be said that the preferred embodiment is applied to a head cover as described above.
[0017]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to FIG.
[0018]
In this embodiment, the head cover 301 that covers the cylinder head is made of a porous material that can transmit at least a part of sound waves emitted from the engine.
[0019]
The head cover 301 has one or more through holes penetrating from the engine side to the opposite side (outside world).
[0020]
The method of manufacturing such a head cover 301 is not a main part of the present invention, and may be any method known to those skilled in the art. Therefore, detailed description is omitted. However, in any case, it is necessary to design such that interference due to a difference in sound speed as described later occurs.
[0021]
In the present embodiment, noise (sound waves) generated from the engine travels to the outside world through the head cover 301. In FIG. 3, a line A represents a sound wave (hereinafter, referred to as a sound wave A) generated from the engine E / G as a sound source and transmitted through the porous head cover 301 to the outside. The sound speed of the sound wave A is reduced by passing through the head cover 301 as a medium. That is, the phase changes before and after transmission.
[0022]
A line B represents a sound wave (hereinafter, referred to as a sound wave B) generated from the engine E / G as a sound source and passing through the above-described through hole provided in the head cover 301 to the outside world. The sound wave B is a direct wave, so to speak, as will be apparent to those skilled in the art, since various components are mounted on the cylinder head, the sound wave B is directly transmitted from the engine E / G to the outside world. The term refers to not only the traveling sound wave but also the sound wave that has reached the through-hole through reflection by various components of the cylinder head.
[0023]
In other words, sound wave A is generated by sound wave B being changed by transmission, and there is a speed difference, that is, a phase difference between the two.
[0024]
Here, if the sound wave A has a phase that cancels the sound wave B, interference occurs when the sound waves A come out of the head cover 301 and they come into contact with each other, and the amplitude of the sound wave B can be reduced by the sound wave A. Therefore, in the present embodiment, the head cover 301 is designed so that the sound wave A has a phase that cancels the sound wave B when transmitted through the head cover 301 and reaches the outside of the head cover 301.
[0025]
Specifically, in order for the sound wave A to cancel the sound wave B, the sound wave A needs to have a phase difference of 180 ° with the sound wave B. This 180 ° phase difference is １ ／ wavelength in terms of wavelength.
[0026]
Therefore, in the present embodiment, the material and the shape of the head cover 301 are designed such that the sound wave generated from the engine E / G passes through the porous head cover 301 so that the wavelength becomes １ ／. I do.
[0027]
In order to generate an appropriate phase difference as described above, not only the phase of the sound wave A but also the phase of the sound wave B may be changed by devising the shape of the through hole.
[0028]
As described above, according to the present embodiment, a through hole is provided in the head cover to enable heat radiation from the cylinder head portion, and the weight and weight are reduced by the phase difference between the transmitted sound wave from the head cover and the direct sound wave. The engine noise can be reduced without increasing the manufacturing cost.
[0029]
As is apparent to those skilled in the art, FIG. 3 is a schematic diagram for explaining the concept of the above-described embodiment, and the illustrated shapes, arrangements, scales, relative positional relationships, and the like are all illustrative. It is not intended to limit the scope of the present invention. In particular, it is clear that the number of the above-described through holes is not limited to the three illustrated in FIG.
[0030]
【The invention's effect】
As described above, according to the present invention, it is possible to provide a noise reduction member that simultaneously realizes heat radiation and noise reduction.
[Brief description of the drawings]
FIG. 1 is a partial schematic view of a vehicle engine showing a general head cover.
FIG. 2 is a cross-sectional view schematically showing a noise reduction structure in a conventional head cover.
FIG. 3 is a sectional view schematically showing a head cover according to an embodiment of the present invention.
[Explanation of symbols]
Reference Signs List 101 Head cover 102 Cylinder head 201 Sound insulation material 301 Porous porous head cover

Claims (2)

A noise reduction member that covers at least a part of the sound source,
Made of porous material,
At least one through-hole penetrated from the side of the sound source to the opposite space is provided,
The material and the shape are set so that the first sound wave emitted from the sound source and transmitted through the member and the second sound wave emitted from the sound source and passing through the hole interfere with each other in the space on the opposite side. A noise reduction member characterized by being made. The noise reduction member according to claim 1, which is provided in a vehicle,
The sound source is a vehicle engine,
The member is a head cover attached to the engine.

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