MXPA98009904A - Element of foam material for cavidades de amortiguamiento de son - Google Patents

Abstract

The present invention relates to a foam material element for sound damping cavities, more particularly, extruded light alloy profiles as used in the construction of rail vehicles. The foam material element 10 according to the invention comprises an interleaving of foam material having two layers including an elastic layer 11 and at least one heavy layer 12 applied to the elastic layer 11. The elastic layer 11 consists more particularly of soft foam polyurethane, the heavy layer 12 consisting more particularly of a flocculated foam polyurethane compound. Before being inserted into the cavity 22 that will be damped with sound, the foam material element 10 according to the invention is compressed, sealed by welding in an air tight film 13, so that it can be inserted through an opening 21 of the cavity 22 therein. After insertion and placement of the foam material element 10, the film 13 is opened, as a result of which the foam material element 10 is expanded to such a degree by the ingress of air that at least one heavy layer, Pressurized by the elastic layer, it comes into contact with the walls 23 substantially over a wide area of surface

Description

ELEMENT OF FOAM MATERIAL FOR SOUND DAMPING CAVIDADES DESCRIPTION OF THE INVENTION The invention relates to a foam material element for sound deadening cavities, more particularly to extruded profiles of metal or plastic material, which before being inserted into a cavity is compressed, sealed by welding in an air-tight film. air so that it can be inserted through an opening of a cavity therein, the foam material element expands to a shape which is brought into contact with at least two walls through the film being opened in a air intake after having been inserted into the cavity. Increasing demands fall on a lighter weight structure for both ecological and economic reasons in the field of rail vehicles, this being the reason why more and lighter weight materials are being used in the construction of rail vehicles. Well-suited for car body structures are extruded hollow chamber profiles of light alloy, more particularly of aluminum materials. The disadvantage of using such extruded profiles is the noise they develop. The extruded profiles of aluminum have sound deadening practically zero, that is to say, the excited bending waves in the corresponding carcass structure cushion only very slowly and are capable of being propagated through the entire structure practically without obstruction. This results in a drum noise in the car body structure. On top of this in the case of components of two protections, as is the case with the extruded profiles cited, failures occur in the damping of sound, this phenomenon being called coincident al interruption. In the case of extruded profiles of two protections that have a thickness of earth of 2 to 5 mm and a separation of earth typically of 20 to 70 mm, these interruptions lie in the audible scale and thus have a negative effect on the operation of sound deadening. To remove the drum noise of said extruded profiles, it is known to apply heavy bitumen or plastic films to the wall of the cavities of extruded profiles by spraying, wrapping or joining. In automotive engineering, it is known to eliminate air noise such as whistling and the like in cavities to make use of foam material elements near the shaft bearings, these elements comprising a soft foam material attached to a cardboard material . Before being inserted into the cavity where the sound will be damped, the foam material element is available in a compressed condition and is sealed by welding in an air-tight film. In this compressed condition the foam material element can be easily inserted through an opening in the cavity therein. After insertion into the cavity, it is possible to admit air by opening the film (for example, by breaking or puncturing to open) so that the foam material element expands in a shape that is brought into contact with it. minus two walls. This known foam material element is only suitable for damping the noise coming from the air but not for dampening the noise coming from the material, ie against the drum noise.

This background in which the invention is based in order to provide a foam material element of the aforementioned type, which is suitable for cushioning the noise phenomenon that occurs in cavities, more particularly, in extruded profiles of metal or plastic material . To achieve this object, a foam material element for sound deadening cavities having the characteristics of the rei indication 1 is proposed, the foam material element according to the invention being configured as at least one material structure of two-layer foam (interleaved foam material) incorporating an elastic layer and at least one heavy layer disposed on the elastic layer, means against drum noise are made possible for extruded profiles of plastic or metal material, more particularly light alloys. In the development, the expanded condition of the foam material element, the two heavy layers are brought into contact with the light alloy profile substantially over a wide surface area. In this arrangement, the soft foam material of the elastic layer compresses at least one heavy layer against the walls of the cavity which will be damped from the sound with a specific pressure. This pressurization of the heavy layer by the elastic layer is based on a saturation of the foam material relative to the cavity which will be damped in sound in the direction in which the foam material element expands. In this way, at least one heavy layer of the foam material element according to the invention is in direct contact with the extruded profile of light alloy and coincides with each movement in the vibration of the extruded profile. These vibrations are absorbed by the foam material element partially in the heavy layer and partially through transfer to the elastic layer and are converted to heat. Ideally, the vibration energy can also be destroyed by the two outer layers of light alloy vibrating out of phase. By incorporating the foam material element according to the invention into the cavity that will be sound damped, the flow resistance in the cavity is increased, as a result of which the aforementioned coinciding interruption in sound damping can be reduced.

By increasing the resistance to thermal convection flow, winding is also prevented, as a result of which it is now also possible to reduce the dimension of the thermal insulating layer in vehicle interiors, thereby obtaining savings in material and cost . Other advantageous aspects of the invention are set forth in the rei indications. The invention will now be explained in detail by way of example with reference to the drawings in which: Figure 1 is a schematic sectional view of a foam material element according to the invention in the compressed condition. Figure 2 illustrates the foam material element according to the invention as shown in Figure 1, but in the expanded condition. Figure 3 illustrates how a foam material element is incorporated into a cavity of a profile of light alloy foam material. Figure 1 schematically represents a cross section through a foam material element 10 according to the invention.

The foam material element 10 comprises an elastic layer 11 and two heavy layers 12, the latter being applied to opposite sides of the elastic layer 11. The elastic layer 11 consists more particularly of soft foam polyurethane, the heavy layers 12 consist more particularly from a flocculated foam polyurethane compound. In the condition illustrated in Figure 1, in the foam material element 10 according to the invention it exists in the compressed condition and is sealed by welding in an air tight film 13. By opening the film 13 for example, by breaking it or by puncturing it to open, the air is able to enter inside the film 13, so that the three-layer foam material structure of the foam material element 10 according to the invention is expands This expanded condition 10 'is illustrated in Figure 2, likewise in a schematic sectional view. In this arrangement, the expansion of the foam material element 10 occurs in the direction of expansion as indicated by the double arrow. As is evident from Figures 1 and 2, it is the elastic layer 11 consisting of the soft foam material which mainly expands, while the two heavy layers 12 of a flocculated foam composite applied to both sides of the layer elastic expand only not substantially. These heavy layers 12 of a flocculated foam composition have a very dense construction so that they can be hardly compressed. In contrast, the soft foam material of the elastic layer 11 has an open cell structure, which can be compressed to a high degree. This compressed condition is retained through sealing by welding in the air-tight film 13, this will not be until the film 13 has been opened and the elastic layer is expanded to its original size and shape after the ingress of air. The weight per volume of the flocculated foam composition of the heavy layers 12 represents approximately 100 to 700 kg / m3, preferably between 300 to 400 kg / m3. The weight per volume of the soft foam material of the elastic layer 11 represents approximately 10 to 80 kg / m3, preferably between 40 to 60 kg / m3. The thickness of the heavy layers 12 is on the scale of 2 to 10 mm, preferably 4 to 5 mm. The thickness of the elastic layer 11 is dimensioned as a function of the size of the cavity that will be damped to the sound. Typically, the thickness of the elastic layer 11 is about 5 to 15 mm in the compressed condition (Figure 1) and about 30 to 70 mm in the expanded condition (Figure 2). The air-tight film 13 preferably is a polyethylene diffusion-tight interlayer film, the thickness of which is in the range of about 50 to 300 μm, preferably 150 to 200 μm. To produce a foam material element according to the invention, the strips of the foam material for the elastic layer and for the heavy layers are bonded together and inserted into an air-tight film, more particularly a film of the bag type. Subsequently, the foam material element located in the air tight film is compressed by compressing together. The interior of the film is evacuated and the film is sealed by welding, as a result of which the compressed condition of the foam material element is retained. Figure 3 shows a schematic perspective view of an extruded profile 20 including a cavity 22. Provided along a narrow side 24 of the extruded profile 20 are openings leading into the cavity 22. Through these openings 21, the foam material elements 10 according to the invention for sound deadening the cavity 22 are inserted. In this compressed condition, the foam material elements 10 according to the invention have the shape of an elongated strip. The elements of the foam material 10 are introduced through the openings 21 in the cavity 22 in such a manner indicated by the arrow that the heavy layers 12 are located parallel to the two longitudinal sides 23 of the extruded profile 20, these longitudinal sides defining the cavity 22. In the compressed condition, the foam material elements 10 are narrower than the thickness d of the extruded profile 20 and the clear width of the openings 21 so that they can be pushed through the openings 21 without any problem . As soon as a foam material element 10 has been placed in the cavity 22, the air tight film 13 is opened. This can be done by puncturing or breaking the opening. Preferably, the film 13 is provided with means (not described in detail) to allow no problem to occur in the opening of the film 13, this being, for example, a tear or similar thread welded to the film. After the film 13 has been opened, the air enters into the film 13 and the elastic layer 11 of the foam material element 10 expands, so that the heavy layers 12 of the foam material element 10 are forced against the side walls 23 of the extruded profile 20 defining the cavity 22. The elastic layer 11 is therefore dimensioned such that its thickness in the expanded condition corresponds at least to the thickness d of the cavity 22 of the extruded profile 20. Accordingly , in the finished installed condition of the foam material element 10, the heavy layers 12 of the flocculated foam composition are brought into contact with the sidewalls 23 of the extruded profile of light alloy 20 of substantially large surface area so that the vibrational movements of s of the extruded profile are transferred to the heavy layers 12, from which they are passed partly towards the elastic layer 11. These vibrations rations are absorbed by both the heavy layer 12 and the elastic layer 11 and are converted into heat, as a result of which a block of drum noise is obtained, i.e. the sound damping of the noise coming out of the material that occurs in the extruded profile, according to the invention. In addition to this, the resistance of the flow in the. cavity 22 of the extruded profile is increased by the foam material according to the invention, as a result of which the aforementioned coincidence interruption in sound damping is minimized to a considerable degree. In addition, due to the increase in the thermal convection resistance of the flow, the winding is eliminated. The good thermal insulation properties of the soft foam material of the elastic layer 11 (coefficient of thermal conductivity at 20 ° C:? »0.040 W / mK) also considerably reduces the exchange of heat from outside / inwards, and vice versa.

The example of the embodiment of a foam material element according to the invention as described and illustrated above in the drawings relates to a structure of foam material having a substantially rectangular cross section. Making use of said rectangular cross section in current practice is an ideal case, since the elements of foam material need to be adapted to the geometry of the existing cavity of the extruded profiles used. This is why foam material elements that substantially have a trapezoidal cross section are more frequently encountered in current practice. Just as they are probably the foam material elements that have a triangular cross section. The manufacture and application of the foam material elements according to the invention having such cross sections correspond to the manufacture and application as described above in the case of rectangular cross section. It will be appreciated that it is not absolutely necessary that two heavy layers are disposed on opposite sides of the elastic layer. Rather, it is also contemplated to use only a heavy layer, for example, of triangular cross-section. Thus, it is probably possible to arrange the heavy layers on two joining sides of an elastic layer of triangular or trapezoidal cross-section.

Claims (11)

1. An element of foam material for sound-deadening cavities, more particularly, extruded profiles of metal or plastic material, the element of foam material being compressed, sealed by welding in an air-tight film before being introduced to the cavity, so that the foam material element can be inserted through an opening in the cavity, the foam material element expands in a shape that is brought into contact with at least two walls of the cavity due to the air entering upon opening the film after the foam material element has been introduced into the cavity, characterized in that said foam material element comprises an elastic layer consisting more particularly of a soft polyurethane foam material and therefore less a heavy layer consisting particularly of a flocculated polyurethane foam composite, at least one heavy layer being applied a to the elastic layer and contacting substantially over a wide surface area with the walls of said cavity due to pressurization by the elastic layer in the expanded condition of the foam material element.

2. The foam material element as set forth in claim 1, characterized in that two heavy layers are provided.

3. The foam material element as set forth in rei indication 2, characterized in that two heavy layers are applied to opposite sides of the elastic layer.

4. The foam material element as stated in any of the rei indications 1 to 3, characterized in that at least one heavy layer has a weight by volume of about 100 to 700 kg / m3.

5. The foam material element as set forth in claim 4, characterized in that at least one heavy layer has a weight per volume of about 300 to 400 kg / m 3.

6. The element of foam material as set forth in any of the preceding indications, characterized in that the weight by volume of said elastic layer is approximately 10 to 80 kg / m3.

7. The foam material element as set forth in claim 4, characterized in that the weight by volume of said elastic layer is about 40 to 60 kg / m3.

8. The foam material element as set forth in any of the foregoing indications, characterized in that the air-tight film is an interleaved diffusion-tight polyethylene film.

9. The foam material element as set forth in any of the preceding indications, characterized in that the thickness of said film is approximately 50 to 300 μm.

10. The element of foam material as set forth in any of the preceding indications, characterized in that said film comprises means for opening or for opening by breaking. SUMMARY An element of foam material is described for sound damping cavities, more particularly, extruded profiles of light alloy as used in the construction of rail vehicles. The foam material element 10 according to the invention comprises an interleaving of foam material having two layers including an elastic layer 11 and at least one heavy layer 12 applied to the elastic layer

11. The elastic layer 11 consists more particularly of soft foam polyurethane, the heavy layer 12 consisting more particularly of a flocculated foam polyurethane compound. Before being inserted into the cavity 22 which will be sound damped, the foam material element 10 according to the invention is compressed, sealed by welding in an air tight film 13, so that it can be inserted through a opening 21 of the cavity 22 therein. After insertion and placement of the foam material element 10, the film 13 is opened, as a result of which the foam material element 10 is expanded to such a degree by the ingress of air that at least one heavy layer, Pressurized by the elastic layer, it contacts the walls 23 substantially over a large surface area.