WO2007036440A1

WO2007036440A1 - Sound-proof underbody cover for motor vehicles

Info

Publication number: WO2007036440A1
Application number: PCT/EP2006/066394
Authority: WO
Inventors: Heiko Klein; Eduard Brück
Original assignee: Carcoustics Techconsult Gmbh
Priority date: 2005-09-26
Filing date: 2006-09-15
Publication date: 2007-04-05
Also published as: DE102005046087B3

Abstract

The invention relates to a sound-proof underbody cover for motor vehicles, comprising a plastic hollow member whose bottom face is embodied so as to reduce air resistance and/or in a substantially smooth manner. In order to largely eliminate the noise generated on such an underbody cover by the impact of splashing water or grit, the bottom face of the hollow member is provided with at least one soft wall area (4.1) and at least one relatively hard wall area (4.2). The soft wall area (4.1) and the relatively hard wall area (4.2) are produced using sequential extrusion and/or sequential coextrusion. At least the bare outer surface of the soft wall area (4.1) is embodied in a relatively soft fashion and is arranged closer to a vehicle wheel than the relatively hard wall area (4.2) in the assembled position of the underbody cover (4'').

Description

September 13, 2006

SOUND INSULATING FLOOR COVERING FOR MOTOR VEHICLES

The invention relates to a sound-insulating underbody paneling for motor vehicles, with a hollow body made of plastic, the underside of which is designed to reduce air resistance and / or substantially smooth-surfaced.

Such underbody linings are known, for example, from EP 1 251 062 A2 and DE 100 01 932 A1. They serve to reduce the sound level in the passenger compartment and to improve the cW value of the respective motor vehicle.

The known from EP 1 251 062 A2 underbody paneling has a double-walled construction, is made of plastic and is manufactured in the twin-sheet process or extrusion blow molding process. In the known from DE 100 01 932 Al underbody paneling is also a blow molding.

When disturbing the noise caused by splashing water and / or splinter impact are felt in such underbody panels when the vehicle in question is moved over roads or paths with water retention or Rollsplittbelag. The present invention has for its object to provide an underbody paneling of the type mentioned, with which the problem of caused by splashing and / or splinter impact noise is largely eliminated and their production costs are nevertheless relatively low.

This object is achieved by an underbody covering with the features of claim 1.

The underbody panel according to the invention consists essentially of a hollow body made of plastic, the underside of which is designed to reduce air resistance and / or substantially smooth surface. The hollow body has on its underside at least one soft wall region and at least one wall region which is relatively hard with respect to the soft wall region, wherein the soft wall region and the relatively hard wall regions are produced by sequential extrusion and / or by sequential coextrusion, and the soft wall region at least on his exposed outside is relatively soft and is arranged in the mounting position of the underbody panel closer to a vehicle than the relatively hard wall area.

The or the relatively soft wall portions of the hollow body are arranged where the grit or Spritzwasserbeaufschlagung is optionally greatest. The remaining wall portions of the hollow body are made of relatively hard plastic.

The respective soft wall portion of the hollow body reduces the noise caused by splashing water or splinter impact. The soft wall areas are preferably composed of 90 to 70 wt .-% of a polyolefin or copolyolefin and 10 to 30 wt.% Of a crosslinked or partially crosslinked elastomer. The creation of a soft wall area requires only a comparatively small proportion of a soft component on the underbody paneling. In particular, EPDM can be used as the soft component.

The soft wall areas as well as the relatively hard wall area or areas can in particular be made of polypropylene, with a mixture of polypropylene and EPDM being preferred for the relatively soft wall areas.

The or the relatively hard wall portions of the underbody panel according to the invention can be advantageously prepared from fiber-reinforced polyolefin or fiber-reinforced copolyolefin.

At least one sound-absorbing structure is preferably formed in the wall region or regions of the underbody cladding made of relatively hard plastic. The effect of the sound-absorbing structure is not adversely affected by the or the soft wall portions of the hollow body.

As a result, the noise level caused by splash water and / or splinter impact is thus markedly reduced in the underbody paneling according to the invention. It is also possible to produce the underbody panel according to the invention relatively inexpensively, since for the production of its soft area only a relatively small amount of a soft synthetic material is used. Substance component is required and the production of the different soft or hard areas by means of sequential extrusion and / or sequential coextrusion takes place.

An advantageous embodiment of the underbody panel according to the invention is that the upper side of the hollow body has an acoustically effective structural portion, in which box-shaped or cup-shaped hollow chambers are formed. This embodiment leads to a significant reduction of the noise level in the passenger compartment (interior) of the motor vehicle and thus to an improvement in ride comfort.

Further preferred and advantageous embodiments of the underbody panel according to the invention are specified in the subclaims.

The invention will be explained in more detail with reference to a drawing illustrating several embodiments. Show it:

Figure 1 is a schematic side view of a motor vehicle with an underbody panel, which is shown for illustration in the not yet assembled state.

Figure 2 is a schematic bottom view of a motor vehicle with two mounted on the underbody underbody coatings.

Figure 3 is a schematic bottom view of a motor vehicle with three mounted on the underbody underbody panels. and characters

4 to 10 show seven different embodiments of a subfloor lining according to the invention in a schematic sectional view.

In Fig. 1, a motor vehicle 1 is shown with an underbody 2. The underbody 2 of the motor vehicle extends substantially from the engine compartment 3 to below the trunk. Below the subfloor 2 of the motor vehicle is a double-walled, sound-insulating underbody panel 4 is provided, which is not yet attached to the motor vehicle 1 in Fig. 1. According to the arrows P, the underbody panel 4 is attached to the floor of the motor vehicle by means of screws or other fastening means.

The underbody paneling 4 is integrally formed. It is formed from a blow molded part made of plastic, the bottom of which is designed to reduce air resistance and / or substantially smooth surface. The underbody panel 4 serves to reduce the drag coefficient (cW value). It can therefore also be referred to as a cW fairing or as an aerodynamic underbody fairing.

The underbody panel 4 according to the invention is designed so that it covers a larger portion of the underbody 2 of the motor vehicle. In the figures 2 and 3, two embodiments are shown in which two inventive underbody panels 4 ', 4''spaced from each other on the underbody 2 of a motor vehicle are mounted. A portion of the subfloor 2, in which an exhaust strut (not shown) and / or the rear wheels 5.1, 5.2 driving propeller shaft 6 are arranged, is not covered by the two underbody panels 4 ', 4''.

The hollow body of the respective underbody panel 4 ', 4' 'has on its underside at least one soft wall area 4.1, 4.3 and at least one relatively hard wall area 4.2 on the other hand.

In FIGS. 4 to 10, the soft wall portion (s) 4.1, 4.3 are characterized by a hatching which has alternating thin and thick lines, while the relatively hard wall portions 4.2 are characterized by hatching having only thin lines. In addition, to illustrate the approximate dimensions of the different wall areas 4.1, 4.2, 4.3 dimensional lines are drawn above the underbody panels.

The two wall regions of the one-piece hollow body are produced by sequential extrusion and / or by sequential coextrusion. The soft wall portion 4.1 or 4.3 is formed relatively soft at least on its exposed outer side and in the mounting position of the underbody panel closer to a vehicle 7.1, 7.2 or 5.1, 5.2 arranged as the relatively hard wall area 4.2. The soft wall region 4.1, 4.3 may be single-layered or multi-layered.

The soft wall portions 4.1, 4.3 and the relatively hard wall portions 4.2 of the underbody panel are preferably made of a polyolefin, copolyolefin or multiple polyolefins of the same polyolefin class produced. The soft wall regions 4.1, 4.3 preferably consist of a mixture composed of a polyolefin or copolyolefin and additionally of crosslinked or partially crosslinked elastomers.

In the embodiment shown in FIG. 2, the respective hollow body of the two mutually spaced underbody panels 4 'two relatively soft wall portions 4.1, 4.3, between which viewed in the longitudinal direction of the vehicle, a relatively hard wall portion 4.2 is formed. The soft wall area 4.1 assigned to the front wheel 7.1, 7.2 makes up more than 1/3 of the total length of the underbody cladding 4 '. By contrast, the soft wall region 4.3 assigned to the rear wheel 5.1, 5.2 is substantially smaller, for example only about half as long as the front soft wall section 4.1.

In the embodiment shown in Fig. 3, two underbody panels 4 '' are present, in which the front wheel assigned to the soft wall area 4.1 and the adjoining, relatively hard wall area 4.2 are about the same length. The soft wall region 4.1 assigned to the front wheel thus accounts for approximately half the total length of the underbody lining 4 ". As shown in Fig. 3, an underbody panel according to the invention may also be designed so that it can be mounted on the underbody 2 below the rear region or engine compartment of the motor vehicle. The arranged in Fig. 3 between the rear wheels 5.1, 5.2 underbody panel 4 '''has two outer, relatively soft wall portions 4.1' and 4.3 ', which are about the same size and between which a relatively hard wall portion 4.2 'is formed.

Fig. 4 shows a schematic representation of an inventive underbody panel 4 '' in longitudinal section view. The one-piece underbody paneling 4 '' is designed as a blow-molded part. The underside 8 of the panel 4 '' is formed to reduce the drag coefficient of her equipped with a motor vehicle substantially smooth surface. On the upper side, the hollow body has an acoustically effective structure section 9, in which box-shaped or cup-shaped hollow chambers 10 are formed. The hollow chambers 10 are open to the bottom portion 11 on one side. At least a majority of the hollow chambers 10 forms a common, enclosed in the blow molding airspace.

The box-shaped or cup-shaped hollow chambers 10 are of different sizes and grouped like islands. A part of the hollow chambers 10 is arranged offset from each other (not shown). Each of the hollow chambers 10 has a substantially planar, oscillatable floor section (ceiling section) 12 and transverse thereto chamber walls 13, which are also formed substantially planar. The different size of the hollow chambers 10 results inter alia in that their base area is different in size; and additionally or alternatively by the fact that their depth or the distance of the oscillatory hollow floor 12 to the bottom portion 11 is dimensioned differently.

In the region of the hollow chambers 10 9 point or line-like welds 14 are formed between the bottom portion 11 and the structural part. Some of the Hollow chambers 10 are formed so that their chamber walls 13 are welded at substantially the same height or depth partially with the bottom portion 11 and partially freerkragend are dressed on the bottom portion 11, leaving an air gap S between the end face of the chamber wall 13 and the bottom portion eleventh ,

The hollow body of the underbody paneling 4 "shown in Fig. 4 has a relatively soft section 4.1 and a relatively hard section 4.2 made by sequential extrusion.

The soft section 4.1 is in the mounting position of the underbody panel 4 '' closer to the front wheel of the motor vehicle than the relatively hard section 4.2.

The aspect ratio of soft portion 4.1 to relatively hard portion 4.2 is approximately in the range of 1: 2 to 1: 1, i. the length of the soft hollow body portion 4.1 corresponds to about one third to about half of the total length of the underbody panel 4 ''. The bottom portion 11 of the underbody panel 4 '' is preferably formed with a greater wall thickness than the upper, the subfloor 2 of the motor vehicle facing hollow body portion with the structural part. 9

The two ends of the hollow body formed from an extruded tube are closed by compression and welded. In the closure areas a plurality of apertures 15 for receiving screws (not shown) or other fastening means are provided. The exemplary embodiment illustrated in FIG. 5 differs from the exemplary embodiment according to FIG. 4 only in that the soft wall region 4.1 and the relatively hard wall region 4.2 have a different wall thickness, at least on the underside 8 of the hollow body formed on the smooth surface. It can be seen that the soft wall region has a greater wall thickness d than the relatively hard wall region 4.2. The relatively hard wall region 4.2 may in particular be made of fiber-reinforced polyolefin or fiber-reinforced copolyolefin.

With regard to the exemplary embodiments illustrated in FIGS. 4 and 5, it should also be noted that the soft wall region 4.1 of the hollow body is designed as a single layer. By contrast, FIGS. 6 and 7 show exemplary embodiments of the underfloor lining 4 "according to the invention, in which the softly formed wall region 4.1 of the hollow body is designed in two layers.

In the embodiment according to FIG. 6, the soft wall region 4.1 of the underbody cladding has been produced by sequential coextrusion by extruding on the outside of an extruded tube, which is formed from a relatively hard plastic after solidification, a plastic or elastomer cover layer 4.11 , which remains relatively soft after cooling and solidification.

On the other hand, the underfloor lining shown in FIG. 7 has a two-layered soft wall region 4.1 in which both the outer layer 4.11 and the inner layer section 4.12 are made of a polyolefin or .alpha Copolyolefin extruded containing EPDM or other elastomer, so that this wall portion 4.1 remains relatively soft after solidification. The inner layer portion 4.12 and the outer layer 4.11 are preferably made of similar types of plastics, which are, however, different soft or hard after solidification. The outer layer 4.11 of this wall section is preferably softer than the inner layer section 4.12.

The outside of the relatively soft wall portion 4.1, 4.3, 4.1 ', 4.3' of the underbody paneling according to the invention is preferably designed in each case with a smooth surface. The underside 8 of the underbody panel according to the invention, including its relatively soft wall portion 4.1, 4.3, 4.1 ', 4.3' is formed substantially free of pores.

FIGS. 8 to 10 show exemplary embodiments of the underbody paneling 4 'according to the invention, which each have two relatively soft wall areas 4.1, 4.3, between which a relatively hard wall area 4.2 is formed, viewed in the longitudinal direction of the vehicle. In the middle section 4.3 of the underbody paneling 4 'with the relatively hard wall area 4.3, in turn, an acoustically effective structure 9 with box-shaped or cup-shaped hollow chambers 10 is formed.

The embodiment shown in Fig. 8 differs from the embodiment of FIG. 4, characterized in that in the rear portion of the double-walled underbody panel 4 ', an additional relatively soft wall portion 4.3 is formed, which is associated with the rear wheel (or the rear wheels) of the motor vehicle. The exemplary embodiment according to FIG. 9 has a first, relatively soft wall region 4.1, which is assigned to the front wheel of the motor vehicle and (as in FIG. 6) has a two-layered construction. In the rear portion of the underbody panel 4 ', another soft trained wall portion 4.3 is provided, which is composed of a relatively hard inner layer portion and a contrast soft outer layer 4.31.

The underbody paneling 4 'shown in FIG. 10 consists of a hollow body with a front wall area 4.1 and a rear wall area 4.3, which are each constructed from a relatively soft inner layer section 4.12, 4.32 and a soft outer layer 4.11, 4.31. The properties of these two wall regions 4.1, 4.3 preferably correspond to the soft, two-layer wall region 4.1 according to FIG. 7.

The embodiment of the invention is not limited to the embodiments described above. Rather, a variety of variants is possible, which make use of the specified in the claims invention even with different design. Thus, it is also possible, for example, to design an underbody cladding according to the invention in such a way that its hollow body is monolayered in the region of a first relatively soft wall section 4.1 (eg as in FIG. 6 or 7) and in the region of another, relatively soft wall section 4.3 (eg as in Fig. 4 or 8).

Claims

September 13, 2006P ATENTANSPR O CHE

1. A sound-insulating underbody paneling for motor vehicles, with a hollow body made of plastic, the underside is designed to reduce drag and / or substantially smooth surface, characterized in that the hollow body on its underside (8) at least one soft wall region (4.1, 4.3; 4.1 ', 4.3 ') and at least one relative to the soft wall portion (4.1, 4.3, 4.1', 4.3 ') relatively hard wall portion (4.2, 4.2'), wherein the soft wall portion (4.1, 4.3, 4.1 ', 4.3') and the relatively hard Wall region (4.2, 4.2 ') are produced by sequential extrusion and / or by sequential coextrusion, and wherein the soft wall portion (4.1, 4.3; 4.1', 4.3 ') is relatively soft at least on its exposed outer side and in the mounting position of the underbody paneling (4, 4 ', 4' ', 4' '') closer to a vehicle wheel (7.1, 7.2, 5.1, 5.2) is arranged as the relatively hard wall portion (4.2, 4.2 ').

2. Underbody covering according to claim 1, characterized in that the hollow body is designed as a blow-molded part.

3. Underbody cladding according to claim 1 or 2, d a d e r c h e c e n e c e s e s that

MY / sa 050682WO the hollow body has at least two relatively soft wall regions (4.1, 4.3), between which viewed in the longitudinal direction of the vehicle, a relatively hard wall portion (4.2) is formed.

4. Underbody covering according to one of claims 1 to 3, characterized in that the one or more soft wall portions (4.1, 4.3, 4.1 ', 4.3') and the or the relatively hard wall portions (4.2; 4.2 ') of a polyolefin, copolyolefin or more Polyolefins of the same polyolefin class are made, wherein the soft or the wall regions (4.1, 4.3, 4.1 ', 4.3') consist of a mixture which is composed of a polyolefin or copolyolefin and also of crosslinked or partially crosslinked elastomers.

5. Underbody covering according to one of claims 1 to 4, characterized in that the one or more soft wall areas (4.1, 4.3, 4.1 ', 4.3') from 90 to 70 wt .-% of a polyolefin or copolyolefin and 10 to 30 wt.% Of crosslinked or partially crosslinked elastomers is / are composed.

6. Underbody covering according to one of claims 1 to 5, characterized in that the one or more soft wall portions (4.1, 4.3, 4.1 ', 4.3') and the or the relatively hard wall portions (4.2, 4.2 ') are made of polypropylene, wherein the or the relatively soft wall portions are composed of a blend of polypropylene and EPDM.

MY / sa 050682WO

7. Underbody covering according to one of claims 1 to 6, characterized in that the one or more relatively hard wall regions (4.2, 4.2 ') is made of fiber-reinforced polyolefin or fiber-reinforced copolyolefin / are.

8. An underbody panel according to any one of claims 1 to 7, wherein a sound absorber is integrated therein.

9. underbody covering according to one of claims 1 to 8, d a d e r c h e c e n e c e in that the hollow body has on the upper side an acoustically effective structure section (9) in which box or cup-shaped hollow chambers (10) are formed.

10. Underbody covering according to one of claims 1 to 9, characterized in that the soft wall area (4.1) and the relatively hard wall area (4.2) of the hollow body have a different wall thickness (d).

11. Underbody covering according to one of claims 1 to 10, characterized in that the soft wall region (4.1) of the hollow body is designed as a single layer and / or at least on its underside (8) substantially smooth surface.

MY / sa 050682WO

12. Underbody covering according to one of claims 1 to

10, that is, that the soft wall region (4.1) of the hollow body has a multi-layered, in particular two-layered, construction.

MY / sa 050682WO