JPH10319968A - Soundproofing cover made of synthetic resin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a compact soundproofing cover with excellent soundproofing performance by making it a sandwich structure consisting of a core and a skin layer covering it and constituting the core with elastomer. SOLUTION: The soundproofing cover 9 is provided with the sandwich structure consisting of the core 22 and the hard skin layer 23 covering it. The core 22 is constituted of the elastomer. The core 22 consisting of the elastomer displays an excellent damping property for vibration in a transmission case, and secures the strength of the soundproofing cover 9 by selecting the material quality of the skin layer 23. Then, the soundproofing cover 9 attains compact formation nearly equal to the soundproofing cover of a usual single structure, and is provided with the excellent soundproofing performance. Thus, thickness of a polyurethane foam layer is reduced to nearly 1/2 of a usual case.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a synthetic resin soundproof cover.

[0002]

2. Description of the Related Art Heretofore, as this kind of soundproof cover, a single-layer structure molded from a synthetic resin has been known (for example, see Japanese Patent Application Laid-Open No. 1-111599). The soundproof cover is, for example, attached to the outer surface of a transmission case of a motorcycle via a polyurethane foam layer.

[0003]

However, since the conventional soundproof cover has low soundproof performance, the thickness of the polyurethane foam layer must be increased in order to compensate for such a problem. There is a problem that the soundproof cover becomes large.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide a soundproof cover which is compact and has excellent soundproof performance.

[0005] To achieve the above object, according to the present invention,
There is provided a synthetic resin soundproof cover having a sandwich structure including a core and a skin layer covering the core, wherein the core is formed of an elastomer.

[0006] The core made of an elastomer exhibits excellent vibration damping properties, and the mechanical strength such as the strength of the soundproof cover and the impact resistance can be secured by selecting the material of the skin layer. As a result, it is possible to provide a soundproof cover that achieves substantially the same compactness as the conventional soundproof cover having a single-layer structure and has excellent soundproof performance.

Further, since the soundproof cover having the above configuration can be mass-produced by applying a known sandwich molding method, the manufacturing cost can be reduced.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG. 1, a scooter type vehicle 1 as a motorcycle has a body frame 2, a front wheel 4 steerable by a steering wheel 3 at a front portion thereof, and a power unit 5 at a rear portion. Is supported. The power unit 5 includes an engine 6, a transmission mechanism housed in a transmission case 7 as usual, and rear wheels 8 driven by the engine 6 via the transmission mechanism.

The transmission case 7 is made of an Al alloy, and a synthetic resin soundproof cover 9 is attached to an area extending from the rear end to about two-thirds in the longitudinal direction of the vehicle body.

2 to 5, the soundproof cover 9 has a substantially box shape, and is connected to a side plate 10 facing the outer surface of the transmission case 7 and to an upper edge, a rear edge and a lower edge of the side plate 10. And a peripheral wall 11 facing the upper surface, the rear surface, and the lower surface of the transmission case 7.

As clearly shown in FIGS.
The front edge of the side plate 10 and the front edge of the side plate 10 are successively and inwardly bent to form a U-shaped edge 12. In the vicinity of the U-shaped edge 12, a U-shaped reinforcing rib 13 is formed so as to extend continuously to the inner surface facing portion of the peripheral wall 11 and the inner surface of the side plate 10. These U-shaped edges 12 and reinforcing ribs 13
Are fitted into the transmission case 7 as shown in FIGS.

In the side plate 10, bolt insertion cylinders 16 and 17 having collars 14 and 15 are formed at a portion rearward of the reinforcing rib 13 and at a rear edge thereof, respectively.
The mounting bolts 18 and 19 inserted into the cylindrical portions 16 and 17 are screwed into the screw holes 20 and 21 of the transmission case 7 as shown in FIG. For the purpose of soundproofing, a polyurethane foam layer 24 is provided between the soundproofing cover 9 and the transmission case 7.

As clearly shown in FIGS.
Has a sandwich structure consisting of a core 22 and a hard skin layer 23 covering the core. The core 22 is made of an elastomer. As the elastomer, for example, a thermoplastic olefin (TPO) is used, which includes Orflex (trade name, manufactured by Japan Polyolefin Co., Ltd.),
Mirastomer (trade name, manufactured by Mitsui Petrochemical Co., Ltd.) and the like correspond. On the other hand, the skin layer 23 is usually made of a material used as a constituent material of the soundproof cover, for example, polypropylene, and includes Mitsui Noblen (trade name, manufactured by Mitsui Toatsu Chemicals, Inc.) Made,
Product name).

The core 22 made of an elastomer exhibits excellent vibration damping properties against the vibration of the transmission case 7, and the strength of the soundproof cover 9 can be secured by selecting the material of the skin layer 23. is there. As a result, the soundproof cover 9 can be made as compact as the conventional soundproof cover having a single-layer structure, and has excellent soundproof performance. Therefore, it is possible to reduce the thickness of the polyurethane foam layer 24 to approximately one half of the conventional case.

Next, a method of manufacturing the soundproof cover 9 using the sandwich molding method will be described.

Referring to FIG. 9, injection molding for producing a soundproof cover.
The device 25 is used to inject the molding compound for the skin layer.
First injection unit 27 having 6₁And molding material for core
Injection unit 2 having screw 28 for injecting
7_TwoAnd both injection units 27 ₁, 27_TwoNose to connect
And a split mold 30 that is detachable from the nozzle 29
Have.

The supply passage 31 of the nozzle 29 communicates with the gate 32 of the mold 30, and the gate 32 communicates with the cavity 33 for molding the soundproof cover. In this case, as shown in FIGS.
Is located at the portion where the end face is to be formed.

A hollow outer needle 34 and a solid inner needle 35 are concentrically disposed in the nozzle 29. In the outer needle 34, the valve portion 36 on the distal end side is connected to the supply path 31.
The piston 37 on the base end side is slidably fitted in the cylinder 38. Piston 37 and cylinder 38
Constitutes a supply path opening / closing operation mechanism 39. In the inner needle 35, the valve portion 40 on the distal end side is connected to the outer needle 3
The piston 42 on the proximal end facing the valve hole 41 formed on the fourth valve portion 36 is slidably fitted into the cylinder portion 43 formed on the proximal end of the outer needle 34. Piston 42
The cylinder portion 43 forms a valve hole opening / closing operation mechanism 44.

The outer needle 34 has a tapered outer peripheral surface continuous with the valve portion 36, and the tapered outer peripheral surface
An outer passage 45 is formed between the inner passage 9 and the inner peripheral surface 9. One end of the outer passage 45 to the supply path 31, the other end is adapted to respectively communicate first to the injection unit 27 ₁ through the hole 46 of the nozzle 29. The outer needle 34 has a straight outer peripheral surface on the base end side, and the through hole 46 can be closed by the outer peripheral surface.

The inner needle 35 has a tapered outer peripheral surface connected to the valve portion 40, and an inner passage 47 is formed between the tapered outer peripheral surface and the inner peripheral surface of the outer needle 34. One end of the inner passage 47 is provided in the valve hole 41, and the other end is provided through the outer needle 34 and the through holes 48 and 49 of the nozzle 29.
Each injection unit 27 ₂ is adapted to communicate. The inner needle 35 has a straight outer peripheral surface on the base end side, and the through hole 48 can be closed by the outer peripheral surface.

The following is a description of the production of the soundproof cover 9.
Various steps are sequentially performed. (i) In FIG. 9, the first injection unit 27₁To skin
The layer forming material is charged and held in a molten state.
2 injection unit 27_TwoThe core molding material is charged into the
It is kept in a molten state. (ii) As shown in FIG. 10, the outer passage 45 is “communicated”,
When the inner passage 47 is in the “blocked” state, the first injection unit
Set 27₁Material M for skin layer under the operation of₁The supply path
31, a key for molding the soundproof cover of the mold 30 through the gate 32.
It was injected into the cavity 33. (iii) As shown in FIG. 11, the first injection unit 27₁
The supply passage 31 side of the outer passage 45 is operated by the
And the inner passage 47 is in the “communication” state,
Second injection unit 27_TwoUnder the operation of the core molding material M_Two
And the core molding material M_TwoSupply path 31,
Molding material for skin layer 32 in cavity 32 and cavity 33
M₁And into the skin layer and for the core
Molding material M₁, M_TwoThrough the cavity 33,
Next, the second injection unit 27_TwoWas stopped. (iv) As shown in FIG. 12, the outer passage 45 is “communicated”,
When the inner passage 47 is in the “blocked” state, the first injection unit
Set 27₁Material M for skin layer under the operation of₁Provided by
For the skin layer in the supply channel 31 and the gate 32 and
Core molding material M ₁, M_TwoInto the cavity 33
Thus, the core 22 and the skin layer 23 are formed.
And the first injection unit 27₁Was stopped. (v) The outer and inner passages 45 and 47 are in the “blocked” state
, The mold 30 is separated from the nozzle 29,
The soundproof cover 9 was obtained by opening.

Since the U-shaped edge 12 and the reinforcing ribs 13 of the soundproof cover 9 are thin, the cavities 33 are formed.
The core forming material M ₂ in the portion for molding them does not flow.

According to the above-described manufacturing method, the soundproof cover 9 having the above-described structure can be easily mass-produced, thereby reducing the manufacturing cost of the soundproof cover 9. Further, after one molding operation, the inside of the supply path 31 is filled with the outer layer molding material M _1, so that the next molding operation starts smoothly, and at that time, the skin layer molding material M 1
Since no core forming material M ₂ to ₁ are mixed, the impact resistance of the skin layer 23, a defect such impair the heat resistance and the like are avoided.

When the soundproof cover 9 has a single-layer structure, the rib 1 is formed on the outer surface of the side plate 10 where the reinforcing rib 13 is formed.
3 is likely to appear due to the shrinkage caused by the coagulation contraction force of the core 3. However, if the core 22 exists as described above, the core 2
According to 2, the propagation of the coagulation contraction force to the outer surface side of the side plate 10 can be prevented, and the occurrence of a dent due to the contraction can be reliably prevented.

The position of the gate for injection molding may be the bolt seating surface 16a of the bolt insertion tube 16 near the reinforcing rib 13. When the gate position is determined in this manner, the appearance of the soundproof cover 9 is improved because the gate removal mark is hidden by the bolt head.

[0026]

According to the present invention, a soundproof cover having a compact size and excellent soundproofing performance can be provided by the above-described structure.

[Brief description of the drawings]

FIG. 1 is a side view of a motorcycle.

FIG. 2 is a side view of the soundproof cover.

FIG. 3 is a sectional view taken along line 3-3 of FIG. 2;

FIG. 4 is a sectional view taken along line 4-4 of FIG. 2;

FIG. 5 is a view taken in the direction of arrow 5 in FIG. 2;

FIG. 6 is a side view showing a state where a soundproof cover is attached to the transmission case.

FIG. 7 is a sectional view taken along line 7-7 of FIG. 6;

FIG. 8 is a sectional view taken along line 8-8 of FIG. 6;

FIG. 9 is an end view of a main part of the injection molding apparatus.

FIG. 10 is a first process chart.

FIG. 11 is a second process chart.

FIG. 12 is a third process chart.

[Explanation of symbols]

 9 Soundproof cover 22 Core 23 Skin layer

 ──────────────────────────────────────────────────の Continued on the front page (72) Inventor Yoshitaka Nukata 1-4-1 Chuo, Wako-shi, Saitama

Claims (1)

[Claims] 1. A synthetic resin soundproof cover having a sandwich structure comprising a core (22) and a skin layer (23) covering the core, wherein the core (22) is made of an elastomer.