JPH075318Y2 - Grommet - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention mainly attaches to a through hole formed in a panel of an automobile to protect a wire harness that is passed through the through hole and also to one side of the panel. The grommet for preventing the transmission of noise from the engine compartment to the driver's seat on the other side.

[Conventional technology]

In FIG. 12, the grommet a is integrally formed by a soft member such as rubber, and a supporting cylinder e for the wire harness is continuously provided on one side of the main body portion c having the annular groove b via the shielding wall portion d. There is.

Then, the grommet a is attached by engaging the annular groove b with the peripheral edge of the through hole of the panel p, and the support cylinder is brought into close contact with the wire harness w by the tape t.

In the above structure, a part of the noise generated in the engine compartment is attenuated by hitting the shielding wall portion d and being reflected, but it is not so effective.

[Problems to be solved by the device]

The present invention focuses on the above points, and achieves a sufficient sound insulation effect by integrally forming a sound insulation structure on the shielding wall portion.

[Means for Solving the Problems]

In order to achieve the above object, in the present invention, a supporting cylinder for a wire harness is provided on one side of a main body mounted in a panel hole, and a shield having an outer diameter substantially equal to that of the main body is provided around the supporting cylinder. A wall portion is provided, and a plurality of sound insulating plates are formed in a superposed state through a plurality of annular gaps in the thickness direction of the shielding wall portion, and the outer surface of the shielding wall portion is substantially entirely surrounded. It is characterized in that projections having a chevron cross section are provided in an adjacent state over the surface, and further, a sound insulation hole consisting of a large cavity continuous with a small hole is formed over substantially the entire peripheral surface of the outer surface of the shielding wall. It is characterized by that.

〔Example〕

1 to 3, a grommet A integrally formed of a soft material such as rubber has an annular groove 2 for attaching to a through hole of a panel on an outer peripheral portion of a main body 1, and A support cylinder 4 for the wire harness is provided on one side, and a shielding wall portion 3 having an outer shape substantially equal to that of the main body 1 is continuously provided around the support cylinder 4.

The shielding wall portion 3 is formed thick, and five sound insulating plates 3b are provided by arranging _four annular voids 3a ₁ , 3a ₂ , 3a ₃ , 3a ₄ in parallel from the outer peripheral portion toward the inner peripheral portion. ₁ , 3b ₂ , 3b ₃ , 3b ₄ , 3b
₅ is formed in a polymerized state in the thickness direction.

In the above structure, the noise generated in the engine room first hits the outer sound insulating plate 3b ₁ to be reflected and attenuated, and the sound passing while being attenuated hits the next sound insulating plate 3b ₂ to be reflected and attenuated. In this way, by providing several sound insulation plates in this way, by repeating reflection and attenuation many times, unlike the case where the thickness of the wall is simply increased, the sound insulation effect becomes high. Since the sound insulation wall portion has an outer shape that is substantially the same as the main body portion, the sound insulation effect can be ensured.

In the embodiment shown in FIGS. 4 to 6, the grommet B has quadrangular pyramidal sound insulation projections 3c ₁ , 3c ₂ , 3c ₃ , ... Adjacent to each other in the thickness direction on the entire circumferential surface of the shield wall portion 3. It is projected in the state.

In the above configuration, the noise generated in the engine compartment side, sound insulation protrusion 3c ₂ collides with the inclined surface 3c ₁ 'sound insulating projections 3c _1, 3c ₃
It is reflected and attenuated by hitting the inclined surfaces 3c ₂ ′ and 3c ₃ ′, and a high sound insulation effect can be obtained by repeating such reflection and attenuation several times.

In the embodiment shown in FIGS. 7 and 8, annular sound-insulating protrusions 3d ₁ , 3d ₂ , 3d ₃ having a mountain-shaped cross section are concentrically formed on the shielding wall portion 3 of the grommet c.

In the embodiment shown in FIGS. 9 to 11, the grommet D is located on the entire circumferential surface of the shielding wall 3 and is adjacent to the sound insulating hole 3g composed of the large cavity 3f continuous with the small hole 3e directed in the thickness direction. In, many are evenly arranged.

In this configuration, the air in the small hole 3e vibrates violently due to the resonance frequency determined by the mass of the air in the small hole 3e and the elasticity of the air in the large cavity 3f, and this movement causes some energy to be heated due to the viscosity of the air. In addition, part of the energy is re-emitted as sound, and the sound absorption utilizing the resonance phenomenon of the air prevents the engine sound from penetrating into the room.

〔effect〕

Since the present invention is configured as described above, it has a feature that effective sound insulation can be achieved by an integrated sound insulation structure provided in the shielding wall portion of the grommet.

[Brief description of drawings]

FIG. 1 is a front view of an embodiment of the present invention, FIG. 2 is a partially cutaway side view of the same as above, FIG. 3 is an enlarged cross-sectional view of an essential part of the same as above, and FIG. An example front view, FIG. 5 is a partially cutaway side view of the above, FIG. 6 is an enlarged cross-sectional view of the main part of the same, FIG. 7 is a front view showing another embodiment of the present invention, Is a partially cutaway side view of the same as above, FIG. 9 is a front view showing another invention of the present invention, FIG. 10 is a partially broken side view of the same as above, and FIG. FIG. 12 is a partially cutaway side view of the conventional example. A, B, C, D ... Grommet, 1 ... Main body, 3 ... Shielding wall, 3
b ₁ , 3b ₂ , 3b ₃ …,… Sound insulation board, 3c ₁ , 3c ₂ , 3c ₃ …, 3d ₁ , 3d
₂ , 3d ₃ … Sound insulation protrusion, 3g… Sound insulation hole.

Claims (3)

[Scope of utility model registration request] 1. A support cylinder for a wire harness is provided on one side of a main body mounted in a panel hole, and a shield wall portion having an outer diameter substantially equal to that of the main body is provided around the support cylinder. A grommet characterized in that a plurality of sound insulating plates are formed in a superposed state through a plurality of annular gaps in the thickness direction of the portion. 2. A shield wall portion is provided on one side of a main body portion to be mounted in a panel hole, and projections having a chevron cross section are provided adjacent to each other over substantially the entire outer peripheral surface of the shield wall portion. And grommet. 3. A sound insulation hole formed by providing a shield wall on one side of a main body to be mounted in a panel hole, and forming a large cavity continuous with a small hole over substantially the entire outer peripheral surface of the shield wall. A grommet characterized by being formed by.