JPS59114167A - Structure of dash panel of automobile - Google Patents

Abstract

PURPOSE:To contrive effective reduction of noise in a car, by mounting a dash outer panel acting as a dynamic damper on the front of a dash inner panel through a rubber component. CONSTITUTION:Insulation of a propagating sound in the air is performed by sticking felt 21 coated with a sheet made of vinyl chloride on the back of a dash inner panel 13. A laterally long rectangular dash outer panel 22 is arranged on about the central part of the front of the dash inner panel 13 at a predetermined space (t), four coners of which are fixed to the dash inner panel 13 through rubber mounts 23. As the dash outer panel 22 is made of heavy rigid body such as a steel plate and the rubber mount 23 is made of an elastic body, they are used as a countermeasure for insulation of a propagating sound in the air through a resonance system due to both of them and at the same time they are used as a countermeasure for insulation of a propagating sound through vibration by making them act as a dynamic damper.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in the structure of a dash panel of an automatic turret, particularly taking sound insulation measures into consideration.

Conventional - As shown in FIG. 1, in order to prevent noise from the engine room 1 side from being transmitted into the passenger compartment 2, the dash panel is connected to the dash inner panel 3 and the dash outer spring/
It has been proposed to have a double structure with I/4 and fill the space with soundproofing material 5 (Utility Model Application No. 53-69914).
.

By the way, the noise inside a car is shown in Figure 4 (al and 4).
As shown in Fig. 1 rbl, 3000rPm, racing, front seat sound is an example, it is composed of vibration-propagated sound (solid vibration sound) from the engine etc. and air-propagated sound, and the former generally has a low frequency of 500Hz or less. Dominates the sound of waves, the latter is 5QQ
)lz or higher, the noise inside the vehicle can be effectively reduced by reducing vibration-propagated sound in the low-frequency range and air-propagated sound in the high-frequency range.

However, although the above-mentioned double dash panel structure has a good sound insulation effect against airborne noise (high frequency sound), it has a poor sound insulation effect against vibration propagation noise (low frequency sound). It has been difficult to effectively reduce in-vehicle noise.

The present invention has been made in view of the above-mentioned conventional problems.
Coupled with the adoption of a double dash structure that is effective at damping air-borne sound, the dash outer panel, which acts as a dynamic damper that absorbs vibration-borne sound, is attached to the front of the dash inner panel via a rubber piece, making it possible to improve the interior of the vehicle. This makes it possible to effectively reduce noise.

Embodiments of the invention will now be described in detail with reference to the accompanying drawings.

As shown in FIGS. 2 and 3, the dash inner panel 13 that partitions the engine room 11 side and the vehicle interior 12 side of the automobile 10 stands up continuously from the floor 14 at a substantially right angle, and its upper end is connected to the front window 15. It is joined to both ends of the dash upper 17 and cowl plate 18 of the cowl box 16 that supports the cowl box 16. A bonnet 19 is located above the cowl plate 18.

Rear surface of the dash inner panel 13 (vehicle compartment 12 side)
A felt (sound absorbing material) 21 covered with a vinyl chloride sheet 20 is pasted on almost the entire surface of the board to insulate airborne sound.

On the other hand, a horizontally rectangular dash outer panel 22 is arranged approximately at the center of the front surface of the dash inner panel 13 (on the side of the engine room 11) with a predetermined distance t from the curved surface of the dash inner panel 13. 4Ill column mount (rubber member) 23. of the dash outer panel 22. . . , is attached to the dash inner panel 13 via 23.

The distance t between the dash inner panel 13 and the dash outer panel 22 may be left as an air layer, or may be filled with felt as a sound absorbing material similar to the above.

The dash upper panel 22 is made of a heavy and rigid base plate, and the rubber mount 23 is an elastic body, so the resonance system created by both of them serves as a sound insulation measure against air-borne sound, and at the same time, this resonance system is dynamic. It acts as a damper to insulate vibration-propagated sound.

With the above configuration, as is clear from the graph showing the noise level of vibration-propagated sound in Figure 5 (al.
According to the theoretical value of the proposed structure shown by the dotted line, compared to the conventional structure shown by ``l'', the overwhelmingly high peak level of the height due to low frequency damage is reduced due to its action as a dynamic damper. I understand.

Furthermore, as is clear from the graph showing the noise level of airborne sound in Fig. 5 fbl, the resonance system It can be seen that the sound insulation effect is large in the high frequency range that is more than Vi times the resonance frequency 0) due to the damping effect.

However, the number of levels increases somewhat near the resonance frequency (fO), but which frequency range is shown in Figure 4 (a', 4).
As explained in relation to Figure △ lbl, since vibration-borne sound is dominant, it is possible to cancel the deterioration equation of air-borne sound by lowering the frequency of the vibration-produced sound, and to further reduce it. can.

Figure 5 (cl) is a graph showing the noise level of vibration-borne sound + air-borne sound, that is, the final car body noise. According to theoretical values, it can be seen that in-vehicle noise is significantly reduced by about IQdB in the low frequency range and about 5dB in the high frequency range.

As is clear from the above description, the present invention has a dash panel structure in which a dash outer panel is attached to the front of a dash inner panel via a rubber member, so vibration propagation noise in the low frequency range is reduced. This, combined with the reduction of airborne sound in the high frequency range by the two-ton dash structure, effectively reduces interior noise.

[Brief Description of the Drawings] Fig. 1 is a vertical sectional view of a conventional dash panel structure, Fig. 2 is a front perspective view of an automobile adopting the dash structure according to the present invention, and Fig. 3 is the dash of Fig. 2. Longitudinal cross-sectional view of the structure, No. 4
Figure 1at is a graph showing the relationship between the noise level and frequency range of vibration-borne sound and air-borne sound; Figure 4.1at is a graph showing the relationship between the energy ratio of vibration-borne sound and air-borne sound and the frequency range; Figure (al is a comparison graph of vibration-borne sound between the conventional structure and the proposed structure, Figure 5 ibl is a comparison graph of nitrogen-borne noise between the conventional structure and the proposed structure, It is a comparison graph of noise. 10... Own 1 + car, 11... Engine l seam, 1
2...Vehicle interior, °13...-Dash inner panel%
14...Floor% 16...Cowl box, 2
1... Hue Ireto, 22... Dash outer panel, 23... Rubber mount. Patent applicant: Toyo Kogyo Co., Ltd. Agent
People Patent Attorneys Aohaku, 2 people, Bōgai, Figure 1, Figure 2, n

Claims (1)

[Claims] (1) A dash panel that separates the engine room and the passenger compartment, and the dash panel includes a dash inner panel that rises continuously from the floor and is joined to the cowl box section above, and a dash inner panel that is connected to the engine room side of the dash inner panel. The dash outer panel is arranged at a predetermined distance from the front of the dash inner panel, and is attached to the dash inner panel via a rubber member. A structure of an automobile dash panel characterized by: