JP3082593B2 - Engine noise prevention cover - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an engine noise prevention cover suitable for a vehicle having a large engine driving noise such as a truck.

[0002]

2. Description of the Related Art In a vehicle having a loud engine sound, such as a cab-over type vehicle such as a truck equipped with a diesel engine, in order to prevent the sound generated from the engine from being emitted into a driver's cab or an external environment, for example, a real-time engine is used. A noise prevention cover as described in JP-A-3-87835 is employed.

Conventionally, as this kind of noise prevention cover, a cover in which glass wool is laminated inside an iron plate formed in a shape to cover an engine, and the engine driving sound is absorbed by the glass wool has been used. In this conventional product, in order to prevent the glass wool from scattering, the surface of the glass wool is covered with aluminum foil, and the iron plate, the glass wool and the aluminum foil are fastened by a fixing member such as a rivet or a stapler. As a noise prevention cover other than the above, a noise prevention cover in which urethane foam is adhered to the inner surface of a resin panel is also in practical use.

[0004]

Among the above conventional products, those made of iron plate, glass wool and aluminum foil are:
The sound generated from the engine was reflected by the aluminum foil, and the sound absorbing effect of the glass wool was reduced, so that satisfactory noise prevention performance could not be obtained. Also,
In order to recycle such a noise prevention cover, it is necessary to separate the iron plate, the glass wool and the aluminum foil, and there is a problem that it takes a lot of time to recycle.

On the other hand, in the case of a noise prevention cover in which urethane foam is adhered to a resin panel, even if the resin panel is a recyclable resin, it is practically difficult to recycle the urethane foam. In order to recycle the cover, urethane foam must be separated from the resin panel, which is troublesome. Accordingly, it is an object of the present invention to provide a noise prevention cover which is lightweight, has a high noise prevention effect, and is easily recyclable.

[0006]

A noise-preventing cover according to the present invention, which has been developed to achieve the above object, comprises a panel-shaped sound-insulating substrate made of a thermoplastic synthetic resin and disposed at a position covering an engine. comprising a thermoplastic synthetic resin fibers made of an aggregate of and the sound insulation surface while being laminated on the surface of the engine side of the substrate is a thermoplastic fibrous skin layer covered with felt-like sound absorbing material, the sound insulating substrate Part of the first
A plate, a second plate, and a cavity existing between the two plates.
And a double-walled structure
The first plate and the second plate are partially overlapped with each other in the thickness direction, and
A sound-insulating substrate provided with a one-piece
The thickness of the sound-absorbing material laminated on one plate
The thickness is smaller than the thickness of the sound absorbing material . A water repellent nonwoven fabric is suitable for the skin layer.

The sound insulating substrate, the sound absorbing material and the skin layer are all made of polypropylene (PP), polyethylene terephthalate (PET), polyphenylene ether (PPE), polyamide (PA), (PP + PPE), (PA + PP
Thermoplastic resins such as E) are suitable. If the shielding substrate is formed by blow molding the above resin into a double wall structure, the sound insulation effect can be enhanced and the rigidity can be increased. If blow molding is difficult depending on the type of the resin, the stampable sheet may be formed into a predetermined shape by stamping.

[0008]

A part of the driving sound generated from the engine is absorbed by the sound absorbing material and the skin layer, and is prevented from going outside by the sound insulating substrate, so that the noise level of the engine can be effectively reduced. .

According to a second aspect of the present invention, if a water-repellent non-woven fabric is used for the skin layer and the sound-absorbing material is covered by the non-woven fabric, liquid or dust such as oil or water is prevented from being absorbed by the sound absorbing material. It is possible to prevent dirt and improve the appearance.

According to a third aspect of the present invention, if the sound insulating substrate, the sound absorbing material and the skin layer are made of the same kind of resin, and they are fixed to each other by fusion bonding, the sound insulating substrate, the sound absorbing material and the skin layer can be used for recycling. Work to separate
It can be used as recycled material as it is.

[0011] Double wall construction on sound insulation board by blow molding
Providing structural parts can increase the strength while being lightweight.
And increase the noise attenuation effect.
You.

In the present invention, in addition to the double-wall structure, a single-plate part is provided in which a part of the first plate and a part of the second plate are overlapped with each other in the thickness direction and integrated. Therefore, the rigidity of the sound insulating substrate can be further increased.

[0013] Further, the thickness of the sound absorbing material laminated on one plate portion of the sound insulating substrate is smaller than the thickness of the sound absorbing material in other portions. Therefore, it is easy to cut a part of the sound absorbing material, and the appearance of the cut portion can be prevented from being deteriorated. For this reason, one type of noise prevention cover can support a plurality of types of engines.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the illustrated noise prevention cover 10. FIG. The noise prevention cover 10 shown in FIG. 1 includes a panel-shaped sound insulating substrate 11 made of a thermoplastic synthetic resin, and a felt-shaped sound absorbing material 12 made of an aggregate of thermoplastic synthetic resin fibers.
2 and 3 show an example of a cross section of the noise prevention cover 10.

The illustrated noise prevention cover 10 covers, for example, the rear side of the engine, and has a shape corresponding to the shape of the engine body and accessories. The lower surface and side surfaces of the engine are also covered with a cover having the same structure as that of the noise prevention cover 10, but the illustration is omitted because the basic configuration is common. That is, the shape of the noise prevention cover 10 is not limited to the illustrated example.

The sound insulating substrate 11 is disposed at a position covering the engine, and is formed into a shape as shown in FIG. 4, for example. If the noise prevention cover 10 has a relatively low temperature (100
When the substrate 11 is used, the material of the substrate 11 is polypropylene (PP). When the noise prevention cover 10 is used at a relatively high temperature (100 ° C. or higher), an example of the material of the substrate 11 is polyethylene terephthalate (PET).

As shown in FIG. 2, a portion 15 of a double wall structure is provided on a part of the sound insulating substrate 11. The portion 15 of the double-wall structure has a first plate 16, a second plate 17, and a hollow portion 18 existing between the two plates 16, 17, and has a closed hollow cross section. . Such a double-walled section 15 can be formed by a known blow molding process. That is, two blanks (plates 16 and 17) heated to the softening temperature are set in a molding die, and air is blown between the plates 16 and 17 to form a double wall corresponding to the inner surface of the die. The part 15 of the structure is molded.

When it is difficult to blow-mold a large resin product such as a polyethylene terephthalate resin, a known stamping process for a stampable sheet may be employed.

A flange 25 is provided on the peripheral edge of the sound insulating substrate 11 so as to rise in the thickness direction. Further, a bracket 26 is provided on a peripheral portion of the sound insulating substrate 11, and the bracket 26 can be fixed to the engine side or the chassis side by appropriate fixing parts such as bolts. .

Further, one or more concave portions 30 are provided at appropriate places on the sound insulating substrate 11. As shown in FIG. 2 and the like, at least one of the first plate 16 and the second plate 17 is recessed toward the other, and the first plate 16 and the second plate Are stacked one on the other in the thickness direction, and are integrated by fusion or the like, and a single plate portion 3
1 is formed. The rigidity of the substrate 11 is enhanced by the concave portions 30 and the flange portions 25 and the like.

A sound absorbing material 12 is laminated on a surface of the sound insulating substrate 11 on the engine side. The sound absorbing material 12 is formed in a shape as illustrated in FIG. This sound absorbing material 12 compresses an aggregate of thermoplastic synthetic resin fibers to, for example, 10 mm.
It is a felt-like nonwoven fabric formed to a thickness of about 25 mm, and is fused to the sound insulating substrate 11.

The surface of the sound absorbing material 12 is covered with a skin layer 35. The skin layer 35 is made of a nonwoven fabric subjected to a water-repellent treatment, and is fixed to the surface of the sound absorbing material 12 by fusion or with an adhesive.

In order to fix the sound insulating substrate 11, the sound absorbing material 12, and the skin layer 35, the parts to be bonded may be melted by high-frequency induction heating and bonded by pressing. Alternatively, the sound insulating substrate 11, the sound absorbing material 12, and the skin layer 35 may be bonded by applying heat with a hot melt sheet made of the same type of thermoplastic resin interposed between the bonded portions.

When the noise prevention cover 10 is used in a portion having a relatively low temperature, the above-mentioned polypropylene-based sound insulating substrate 11, the polypropylene-based sound absorbing material 12 made of a felt-like fiber aggregate, and the polypropylene-based A skin layer 35 made of a nonwoven fabric may be used.

In this case, a portion where the thickness of the cover 10 is less restricted, such as a space portion (referred to as an extra space portion) where the distance between the cover 10 and the engine can be increased, as shown in the cross section in FIG. And the thickness of the sound absorbing material 12 is sufficiently increased (for example, 20 mm or more).
Good to take. In a portion where the thickness of the cover 10 is largely restricted, such as a narrow space where there is no allowance for the distance between the cover 10 and the engine, the substrate 11 has a double wall as shown in a portion A in FIG. This is dealt with by reducing the thickness by adopting the single-plate portion 31 without using a structure, and making the thickness of the sound absorbing material 12 thinner than the marginal space portion.

When the noise prevention cover 10 is used at a relatively high temperature portion, a PET-based sound insulating substrate 11 having high heat resistance, a PET-based sound absorbing material 12 made of a felt-like fiber aggregate, and a PET It is preferable to use a skin layer 35 made of a non-woven fabric. And cover 10 like a room
The thickness of the sound-absorbing material 12 is sufficiently set in a portion where the thickness of the sound absorbing material is small, and in a portion where the thickness is limited such as a narrow space portion,
This is dealt with by making the thickness of the sound absorbing material 12 thinner than the extra space.

Further, the cover 1 may be used in accordance with the type of the engine or the like.
The single-plate portion 31 is provided along a portion to be cut (for example, a portion indicated by a two-dot chain line in FIG. 1) so that a part of 0 can be cut. The sound absorbing material 12 is 1
The thickness of the portion 12a laminated on the portion 31 of the sheet is made smaller than the thickness of the other portions 12b. Therefore, it is easy to cut off a part of the substrate 11 and the sound absorbing material 12 in the single-plate portion 31 according to the type of the engine, and
Opening of the cut surface is also avoided. FIG. 6 shows a state where a part of the cover 10 is cut off.

Since the noise-preventing cover 10 of the above embodiment uses a water-repellent nonwoven fabric for the skin layer 35, the absorption of the liquid or dust such as oil or water by the sound absorbing material 12 is avoided. 12 does not impair the sound absorbing ability.

The noise prevention cover 10 is mounted on the substrate 1
1, the sound absorbing material 12 and the skin layer 35 are made of the same type of resin, and the substrate 11, the sound absorbing material 12 and the skin layer 35 are fused to each other. Can be used as In addition, since the portion 15 having the double wall structure is provided on a part of the substrate 11, the strength can be increased while being lightweight,
Moreover, the noise attenuation ability can be increased.

In the above-described noise prevention cover 10, part of the sound generated from the engine is partially covered with the skin layer 35 and the sound absorbing material 12.
Further, since the sound is shielded by the substrate 11 and the sound is shielded by the substrate 11, the noise emitted to the outside is significantly reduced.

When the substrate 11 made of polypropylene is used, the plate thickness t per sheet in the portion 15 of the double wall structure
The sound insulation performance of three types of substrates 11 of 2 mm, 3 mm, and 4 mm was measured while changing the distance d between the hollow portions 18 to 5 mm, 10 mm, and 25 mm. As a result, when d is 5 mm and the plate thickness is 3 mm, the sound pressure level is reduced by about 8 dB as compared with the case where the plate thickness is 2 mm, and when the plate thickness is 4 mm, the sound pressure level is 2 mm. It was confirmed that the sound pressure level was reduced by about 15 dB in comparison.

Further, when d is 10 mm and the thickness is 3 mm, the sound pressure level is reduced by about 5 dB as compared with the case where the thickness is 2 mm, and when d is 4 mm, the sound pressure level is lower than when the thickness is 2 mm. About 8 dB. Furthermore, d is 25 mm and the plate thickness is 3 mm
In the case of (1), the sound pressure level was reduced by about 1 decibel as compared with the case of the plate thickness of 2 mm, and when the plate thickness was 4 mm, the sound pressure level was lowered by about 6 dB than in the case of the plate thickness of 2 mm. And, as d was larger, the decrease in sound pressure level was larger.

As described above, the noise reduction effect is greater as the thickness of the substrate 11 is larger, but if the thickness exceeds 4 mm,
Since the cover becomes heavier than a cover using a conventional iron plate (plate thickness 0.8 mm), the plate thickness is preferably up to 4 mm. Also,
If the plate thickness is less than 2 mm, the rigidity of the substrate 11 is insufficient, and a desired noise prevention effect may not be obtained. Therefore, the plate thickness is desirably 2 mm or more. When the distance d between the hollow portions 18 is 10 mm or more, the noise prevention effect is high. However, when d exceeds 25 mm, the portion 15 of the double wall structure becomes too thick, and it may be difficult to accommodate it in the current engine room. Therefore, the practical value of d is suitably in the range of 10 mm to 25 mm.

[0034]

According to the present invention, a noise prevention cover for an engine which is easy to recycle, lightweight, and has a high noise prevention effect can be obtained. And in the present invention,
With the double wall structure, it is lightweight but
Strength and increase the noise attenuation effect.
Can be In addition to the part of the double-walled structure,
The first plate and a part of the second plate are overlapped with each other in the thickness direction.
Since the integrated one-plate part is provided, the sound insulation substrate
Can be further increased in rigidity. Further, the sound insulation base
The thickness of the sound-absorbing material laminated on one sheet of the board
Is thinner than the thickness of the sound absorbing material.
Cut a part of the sound insulating board and sound absorbing material in the part
And the appearance of the cut part becomes poor.
You can avoid. For this reason, even one type of noise prevention cover
It is possible to support various types of engines.

[Brief description of the drawings]

FIG. 1 is a front view of a noise prevention cover according to an embodiment of the present invention.

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

FIG. 3 is a sectional view taken along the line III-III in FIG. 1;

FIG. 4 is a front view of a sound insulating substrate used for the noise prevention cover shown in FIG. 1;

FIG. 5 is a front view of a sound absorbing material used for the noise prevention cover shown in FIG. 1;

FIG. 6 is a front view showing a state where a part of the noise prevention cover shown in FIG. 1 is cut away.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Noise prevention cover 11 ... Sound insulation board 12 ... Sound absorbing material 15 ... Double wall structure part 16 ... 1st board 17 ... 2nd board 18 ... Cavity part 31 ... 1 board part 35 ... Skin layer

Continuation of the front page (56) References JP-A-6-123237 (JP, A) JP-A-61-1446 (JP, U) JP-A-2-103137 (JP, U) (58) Fields investigated (Int) .Cl. ⁷ , DB name) F02B 77/13 F02B 77/11

Claims (3)

(57) [Claims] 1. A panel-shaped sound insulating substrate made of a thermoplastic synthetic resin and arranged at a position covering an engine, and an aggregate of thermoplastic synthetic resin fibers laminated on an engine-side surface of the sound insulating substrate. the surface and the thermoplastic fibrous skin layer covered with felt-like sound absorbing material while being
A first plate, a second plate, and both plates are provided on a part of the sound insulating substrate.
A double-walled structure with a cavity
And a part of the first plate and the second plate are overlapped with each other in the thickness direction.
And the sound insulation
The thickness of the sound absorbing material laminated on the single plate
A noise prevention cover for an engine, characterized in that the thickness is smaller than the thickness of the sound-absorbing material at the part . 2. The noise prevention cover according to claim 1, wherein said skin layer is made of a water-repellent nonwoven fabric, and said nonwoven fabric is adhered to said sound absorbing material. 3. The sound-insulating substrate, the sound-absorbing material, and the skin layer are each made of the same type of resin selected from polypropylene or polyethylene terephthalate, and the sound-insulating substrate and the sound-absorbing material are fused to each other. The noise prevention cover according to claim 1, wherein