Pneumatic vehicle tire having an acoustic element

Abstract

The invention relates to a pneumatic vehicle tire (L) having at least one acoustic element (8), wherein the tire (L), fitted on a wheel rim (16), encloses with the rim (16) a space inside the tire (17), wherein the acoustic element (8) comprising a body (12) and a layer (13) is arranged on an inner tire surface (10) involved in delimiting the space inside the tire (17), wherein the body (12) is arranged on the inner tire surface (10) and wherein the layer (13) is arranged on a surface region of the body (12) that is facing the space inside the tire (17). The object is to provide a tire which has improved acoustic properties with less use of porous noise-reducing material and the acoustic element of which is more resistant to pressure changes. This is achieved in that the layer (13) is arranged on at least 15% of that surface of the body (12) which faces toward the space inside the tire (17), in that the layer (13) has a first surface region (9) which is arranged at a distance from the inner tire surface (10), in that the first surface region (9) is connectable pneumatically to a surface region (11) lying opposite it and in that the layer (13) has a sound reflectance of at least 80% for a sound wave striking the first surface region (9). The invention also relates to a wheel rim (16) and to a wheel having such an acoustic element (8).

Claims

1. A pneumatic vehicle tire comprising: at least one acoustic element enclosed within a space inside the vehicle tire and the wheel rim and positioned radially inward of a profiled tread of the vehicle tire; the at least one acoustic element comprises a body and a layer, and the at least one acoustic element is arranged on an inner tire surface involved in delimiting the space inside the tire, the body is arranged on the inner tire surface, and the layer is arranged on an inner surface region of the body that is facing the space inside the tire; the layer of the at least one acoustic element is arranged on at least 15% of the surface of the body, the layer has a first surface region arranged at a distance from the inner tire surface and facing the space inside the tire, and the first surface region has an air connection to a second surface region of the layer which is lying opposite the first surface region; the layer of the at least one acoustic element has a sound reflectance of at least 80% for a sound wave striking the first surface region which is measured at a reference frequency (f) of:
f=c/((R+r).Math.π) where R is the nominal tire diameter, r is the nominal rim diameter, and c=343 m/s; the first surface region having normal vectors having a radially inward component and the second surface region having normal vectors having a radially outward component to redistribute sound pressure to lower frequencies; the body of the at least one acoustic element comprises a porous foam material for dampening noise.

2. The pneumatic vehicle tire as claimed in claim 1, wherein the layer has one or more of a first surface region which is arranged facing the space inside the tire, and a first surface region which is arranged facing the body.

3. The pneumatic vehicle tire as claimed in claim 1, wherein the layer has a sound reflectance of at least 90% for a sound wave of the reference frequency (f) striking the first surface region.

4. The pneumatic vehicle tire as claimed in claim 1, wherein one or more of the acoustic element and the layer has, at least in the region of the first surface region, a characteristic acoustic impedance of 0.8.Math.10.sup.6 Ns/m.sup.3 to 18.Math.10.sup.6 Ns/m.sup.3.

5. The pneumatic vehicle tire as claimed in claim 1, wherein the layer has, at least in the region of the first surface region, a flexural stiffness of 100 Nm to 6000 Nm.

6. The pneumatic vehicle tire as claimed in claim 1, wherein the acoustic element under the effect of a force perpendicular to the first surface region has a spring constant of 100 N/m to 20 000 N/m.

7. The pneumatic vehicle tire as claimed in claim 1, wherein the layer has at least in the region of the first surface region a flexural stiffness of 6.Math.10.sup.−6 Nm to 1.Math.10.sup.−2 Nm.

8. The pneumatic vehicle tire as claimed in claim 1, wherein all normal vectors of the first surface region form an angle of less than 90º relative a radial direction (rR).

9. The pneumatic vehicle tire as claimed in claim 1, wherein all of normal vectors of the first surface region form an angle of 0° to 45° an axial direction (aR) or circumferential direction (U).

10. The pneumatic vehicle tire as claimed in claim 1, wherein the acoustic element comprises a damping element, which is formed from a porous material and is suitable for reducing noises.

11. The pneumatic vehicle tire as claimed in claim 1, wherein the body has a surface region facing the space inside the tire which is delimited by edges, and wherein the layer is arranged on the surface region, entirely or partially at a distance from the edges.

12. The pneumatic vehicle tire as claimed in claim 1, wherein the layer has a layer thickness of 0.01 mm to 20 mm.

13. The pneumatic vehicle tire as claimed in claim 1, wherein the layer is selected from the group consisting of a plastic film, a metal film, a fabric-reinforced membrane, a layer comprising natural materials, a layer comprising carbon fibers, a layer comprising aramid, a cured coating, a lacquer, a layer of rubber, a coating of the surface of the body, and an untreated outer surface of the body.

14. The pneumatic vehicle tire as claimed in claim 1, wherein the first surface region is formed as closed in a circumferential direction.

15. The pneumatic vehicle tire as claimed in claim 1, further comprising a plurality of more acoustic elements are arranged distributed over the circumference of the tire, the plurality of more acoustic elements each comprising a body having a porous foam material for dampening noise and a permeable layer for conveying air.

16. The pneumatic vehicle tire as claimed in claim 1 as used for a vehicle wheel.

17. A wheel rim comprising at least one acoustic element, wherein a pneumatic vehicle tire, fitted on the wheel rim, encloses with the rim a space inside the tire; wherein the at least one acoustic element comprises a body and a layer, and is arranged on an inner tire surface involved in delimiting the space inside the tire, wherein the body is arranged on the inner tire surface, and wherein the layer is arranged on a surface region of the body that is facing the space inside the tire; wherein the layer is arranged on at least 15% of the surface of the body that is facing the space inside the tire, wherein the layer has a first surface region arranged at a distance from the inner tire surface, and wherein the first surface region can be connected pneumatically to a surface region of the layer which is lying opposite the first surface region; and, wherein the layer has a sound reflectance of at least 80% for a sound wave striking the first surface region which is measured at a reference frequency (f) of:
f=c/((R+r).Math.π) where R is the nominal tire diameter, r is the nominal rim diameter, and c=343 m/s.

18. The wheel rim as claimed in claim 17 as used for a vehicle wheel.

19. A pneumatic vehicle tire comprising: a profiled tread, a carcass connected to the profiled tread and an inner layer connected to the carcass; a bead region connected to a rim; an inside air space defined by the inner layer, the bead region and the rim; an acoustic element bonded to the inner layer radially inward and below the profiled tread, the acoustic element comprising: a body having a porous foam material for dampening noise and a spring constant of 100 N/m to 20 000 N/m; and an air permeable layer connected to the body, the air permeable arranged on at least 15% of the surface of the body and having a flexural stiffness of 100 Nm to 6000 Nm and acoustic impedance of 0.8.Math.10.sup.6 Ns/m.sup.3 to 18.Math.10.sup.6 Ns/m.sup.3 and a spring constant of 100 N/m to 20 000 N/m; the air permeable layer further having a sound reflectance of at least 80% for a sound wave striking the first surface region which is measured at a reference frequency (f) of:
f=c/((R+r).Math.π) where R is the nominal tire diameter, r is the nominal rim diameter, and c=343 m/s.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Further features, advantages and details of the invention are now explained more specifically on the basis of the schematic drawings, which depict exemplary embodiments. In the drawings:

(2) FIG. 1 shows a radial partial cross section through a vehicle wheel according to the invention having at least one acoustic element according to the invention;

(3) FIG. 2 shows a radial partial cross section through a vehicle wheel according to the invention having at least one acoustic element according to the invention and

(4) FIG. 3 shows acoustic elements according to the invention.

DETAILED DESCRIPTION

(5) FIG. 1 shows a radial partial cross section through a vehicle wheel with a wheel rim 18 and a pneumatic vehicle tire L of a radial type of construction fitted on the rim 18. The essential components from which the depicted pneumatic vehicle tire L is composed are a largely air-impermeable inner layer 1, a carcass 2 which comprises at least one reinforcing layer and conventionally reaches from the region of the crown of the pneumatic vehicle tire L over the sidewalls 3 into the bead regions 4 and is anchored there by wrapping around high-tensile bead cores 5, a profiled tread 6 located radially outside the carcass 2 and a multi-ply belt assembly 7 arranged between the tread 6 and the carcass 2. This may be a wheel for a passenger car or for a commercial vehicle.

(6) The tire L according to the invention may be fitted in an airtight manner on a wheel rim 16. The wheel rim may be formed in one piece or more than one piece. The space enclosed by the wheel rim and the tire is referred to as the space inside the tire 17, the surface delimiting the space inside the tire 17 as the inner tire surface 10 or as the inner rim surface 18.

(7) Arranged on the radially inner tire surface 10 lying opposite the tread 6 is an acoustic element 8 comprising a body 12 and a layer 13. The body 12 is arranged on the inner tire surface 10 and is connected to it by means of a bonding agent 14.

(8) A layer 13 is arranged on a surface region of the body 12 that is facing the space inside the tire 17. The layer 13 is in this case arranged on at least 15%, preferably on at least 20%, particularly preferably on at least 30%, of the surface of the body 12 that is facing the space inside the tire 17.

(9) The layer 13 has a first surface region 9 facing the space inside the tire 17 and arranged at a distance from the inner tire surface 10. The layer 13 also has a surface region 11 lying opposite the first surface region 9. The two surface regions 9, 11 may be connected by a line running within the layer 13 perpendicularly to the two surface regions 9, 11.

(10) The first surface region 9 can be connected pneumatically to the opposite surface region 11 of the layer. In the case depicted, the layer 13 has for this an arrangement which has around a free end 15 of the layer 13 a connection of the two surface regions 9, 11 through which air can pass. The two surface regions 9, 11 of the layer 13 are consequently arranged in a region of the layer that does not enclose a completely closed space. Such a connection through which air can pass can also be created by an opening through which air can pass in the layer 13 and/or a permeability of the layer 13 with respect to air.

(11) The first surface region 9 of the layer 13 has a sound reflectance of at least 80%, measured at a reference frequency f of f=c/((R+r).Math.r).Math.π) under standard conditions in accordance with DIN EN ISO 10534-2, where R is the nominal tire diameter and r is the nominal rim diameter and c=343 m/s. The sound reflectance may be at least 90%, preferably at least 95%, particularly preferably at least 99%.

(12) The layer 13 has a first surface region 9, which is arranged facing the space inside the tire 17. The opposite surface region 11 is arranged facing the body 12. Also the opposite surface region 11 may be designed as the first surface region with a corresponding reflectance.

(13) The layer 13 has at least in the region of the first surface region 9 a characteristic acoustic impedance of 0.8.Math.10.sup.6Ns/m.sup.3 to 18.Math.10.sup.6Ns/m.sup.3, preferably of 11.Math.10.sup.6 Ns/m.sup.3 to 18.Math.10.sup.6Ns/m.sup.3.

(14) The layer 13 has at least in the region of the first surface region a flexural stiffness of 100 Nm to 6000 Nm and a spring constant of 100 N/m to 20 000 N/m. The layer 13 may however also have at least in the region of the first surface region a flexural stiffness of 6.Math.10.sup.−6 Nm to 1.Math.10.sup.−2 Nm and a spring constant of 100 N/m to 20 000 N/m.

(15) All of the normal vectors 19 of the first surface region 9 and of the opposite surface region 11 form an angle 20 of less than 90°, preferably an angle 20 of 0° to 10°, preferably of 0° to 5°, with the radial direction rR. All of the normal vectors 19 of the first surface region 9 have a radially inwardly oriented component. All of the normal vectors 19 of the opposite surface region 11 have a radially outwardly oriented component. All of the normal vectors 19 of the first surface region 9 are oriented in one direction and all of the normal vectors 19 of the opposite surface region 11 are oriented in the direction opposite thereto.

(16) The acoustic element 8 has a damping element, which is formed from a porous material and is suitable for reducing noises. In this case, the body 12 is formed by the damping element. The damping element is connected to the inner tire surface 10 by means of a bonding agent 14, preferably by means of an automatically sealing sealant. The porous material may be a foam. From radially outside to radially inside, the sequence of elements is as follows: inner tire surface 10, bonding agent 14, damping element 12, layer 13.

(17) The body 12 has a surface region facing the space inside the tire 17 that is delimited by edges 21 and on which the layer 13 is arranged.

(18) The layer 13 has a layer thickness of from 0.01 mm to 20 mm. The layer thickness is the length of the radial extent. Not only layers with a small layer thickness of 0.01 mm to 5 mm but also layers with a moderate layer thickness of between 5 mm and 12 mm and layers with a greater layer thickness of 12 mm to 20 mm have been found to be suitable and advantageous. The layer 13 may be designed as air-permeable or air-impermeable. The layer 13 may be designed as water-impermeable or water-permeable.

(19) The layer 13 may in this case be selected from the group formed by a plastic film, a metal film, preferably an aluminum film, a fabric-reinforced membrane, a layer comprising natural materials, a layer comprising carbon fibers, a layer comprising aramid, a cured coating, a lacquer or a layer of rubber, preferably a layer of sponge rubber, a coating of the surface of the body and an untreated outer surface of the body. Such layers have outstanding reflection properties.

(20) The layer 13 may be designed as an element of the acoustic element 8 other than the body 12, preferably as a film. In this case, the layer 13 may be connected to the body 12 by means of a bonding agent. The layer 13 may comprise natural materials, preferably cork or a resin, preferably an epoxy resin-based resin, or carbon fibers or aramid.

(21) The layer 13 may form or be involved in forming the surface of the body 12. The layer 13 may also be an untreated outer surface of the body 12, preferably an untreated outer surface of the porous material of the damping element. The layer 13 may be the skin of the foam of the damping element that is produced during the foaming. As a result, an efficient acoustic element of a simple construction is created. The coating may be applied in a liquid state to the damping element and then cured. The untreated outer surface may be the untreated outer surface of the porous material of the damping element after the production process of the porous material. It is consequently not a cut surface. It is for example the natural surface of a foam.

(22) In the embodiment depicted, the body 12 and/or the first surface region 9 may be formed as closed in the circumferential direction U. However, the first surface region 9 may also only extend over a partial region of the circumference of the tire. However, the first surface region 9 may also only extend over a partial region of the circumference of the tire L. The acoustic element 8 may have a number of first surface regions 9 which are arranged facing the space inside the tire 17. The acoustic element 8 may also have a number of first surface regions 9 which are arranged facing the body 12. The said surface regions 9 may all be assigned to the same layer 13 or to a number of layers 13 arranged at a distance from one another.

(23) The tire L may also have a number of acoustic elements 8 and/or damping elements.

(24) FIG. 2 shows a partial cross section of a vehicle wheel, wherein an acoustic element 8 having one or more first surfaces 9 is arranged on the inner surface 18 of the wheel rim 16. The acoustic element 8 may be designed in a way corresponding to the acoustic elements 8 described in FIG. 1. The at least one acoustic element 8 is attached to the inner surface 18 of the wheel rim 16 in a bonding manner by means of a bonding agent 14.

(25) FIG. 3 shows various exemplary embodiments of acoustic elements 8 suitable for a pneumatic vehicle tire L as shown in FIG. 1. The acoustic elements 8 are also suitable for attachment to a wheel rim as shown in FIG. 2. In this case, the radial direction is the opposite direction.

(26) The acoustic elements 8 depicted differ from the acoustic element 8 shown in FIG. 1 as follows:

(27) FIG. 3a shows a stump, the side regions of which are surrounded by a layer 13. All of the normal vectors 22 of the first surface regions 9 form an angle 20 of a maximum of 45°, preferably of a maximum of 30°, with the circumferential direction. All of the normal vectors 23 of the first surface regions 9 form an angle of a maximum of 45°, preferably of a maximum of 30°, with the axial direction. The layer 13 has a free end 15.

(28) FIG. 3b shows a largely cuboidal acoustic element 8, wherein the layer 9 is arranged on the entire surface of the body 12 that is facing the space inside the tire 17. The layer 9 is formed as permeable to air.

(29) FIG. 3c shows a further cuboidal acoustic element 8, wherein the body 12 has a surface region facing the space inside the tire 17 that is delimited by edges 21, wherein the layer 13 is arranged on the surface region. The layer 13 in this case only extends over part of the surface region. The layer 13 is arranged entirely at a distance from the edges 21 of the surface region.

(30) FIG. 3d shows a cross section of an acoustic element 8, wherein the body 12 has a through-opening 24. The layer 13 is arranged on the surface of the body 12 lining the opening 24.

LIST OF REFERENCE DESIGNATIONS

Part of the Description

(31) 1 Inner layer 2 Carcass 3 Sidewall 4 Bead region 5 Bead core 6 Tread 7 Belt assembly 8 Acoustic element 9 First surface region 10 Inner tire surface 11 Opposite surface region 12 Body 13 Layer 14 Bonding agent 15 Free end 16 Wheel rim 17 Space inside the tire 18 Inner rim surface 19 Normal vector 20 Angle 21 Edge 22 Normal vector 23 Normal vector 24 Through-opening R Vehicle wheel L Pneumatic vehicle tire aR Axial direction rR Radial direction U Circumferential direction