TYRE COMPRISING A FOAM MATERIAL FOR ACOUSTIC ABSORPTION

Abstract

A tyre comprising an impermeable layer designed to ensure the sealing under pressure of the air contained in the inner cavity of the carcass and a foam material provided on the inside of said inner cavity, wherein the foam material is made up of open cell foam with a cell size or diameter of from 150 to 190 μm and a standard deviation of 5% to 15%.

Claims

1. A tyre comprising an impermeable layer designed to ensure the sealing under pressure of the air contained in the inner cavity of the carcass and a foam material housed on the inside of said inner cavity; wherein said foam material has a porosity made up of open cells having an average size ranging from 150 to 190 μm with a standard deviation ranging from 5% to 15%; said foam material having a density ranging from 10 to 15 Kg/m.sup.3 and being made of polyester-based or polyether-based polyurethane.

2. (canceled)

3. (canceled)

4. (canceled)

5. A tyre according to claim 1, wherein said foam material occupies a volume ranging from 0.1 to 100% of the volume of the inner cavity.

6. A tyre according to claim 5, wherein said foam material has a thickness ranging from 10 to 200 mm and a width ranging from 10 to 100% of the width of the inner cavity.

7. A tyre according to claim 1, wherein said foam material occupies a volume ranging from 0.4 to 20% of the volume of the inner cavity.

8. A tyre according to claim 7, wherein said foam material has a thickness ranging from 20 to 30 mm and a width ranging from 20 to 40% of the width of the inner cavity.

9. A tyre according to claim 1, wherein said foam material is housed on a surface of the impermeable layer of the inner cavity of said tyre.

10. A tyre according to claim 1, wherein said foam material is housed in the cavity in the shape of a toroid, or in the shape of a strip with a length that is equal to the one of the impermeable layer, or in the shape of single segments that are assembled so as to cover the entire length of the impermeable layer.

Description

BEST MODE FOR CARRYING OUT THE INVENTION

[0015] Some embodiment examples are given below for purely illustrative non-limiting purposes.

[0016] The Applicant has made a comparison in terms of acoustic absorption in the frequency range between 180 and 300 Hz between a foam material commonly used in tyres and a series of foam materials according to the present invention.

[0017] The foam material for comparison (Conf) is marketed under the trade name Metzonor 023 and is produced by Metzler Schaum GMBH. In particular, the foam material for comparison in made of polyurethane with a density of 23 Kg/m.sup.3. In particular, the cells of the foam material for comparison have an average size ranging from 250 to 400 μm with a standard deviation ranging from 20% to 30%.

[0018] The foam material of the invention is made of polyurethane and is characterised by a density ranging from 10 to 15 Kg/m.sup.3 and cells having an average size ranging from 150 to 190 μm with a standard deviation ranging from 5% to 15%. In particular, three samples were tested according to the following invention characterised by the following cell dimension: 150 μm (EXP 1), 170 μm (EXP 2) and 190 μm (EXP 3).

[0019] The acoustic absorption test was performed according to the ISO 10534-2 standard at a frequency ranging from 180 to 300 Hz.

[0020] Table I shows the results of acoustic absorption tests indexed to the result obtained with the foam material for comparison.

TABLE-US-00001 TABLE I Conf Exp 1 Exp 2 Exp 3 Acoustic 100 340 300 240 absorption coefficient

[0021] As can be seen from the values in Table I, in the frequency range between 180 and 300 Hz, the foam materials of the present invention ensure an acoustic absorption greater (from approximately two and a half times to three and a half times greater) than that of the foam material for comparison.

[0022] Since the acoustic waves at low frequency (180-300 Hz) are those that characterise the cavity resonance sound generated by the vibrations of the air under pressure, the above evidence shows that the foam material subject of the present invention is able to ensure a general abatement of the noise level coming from the tyre when it is running.