Technical Field of the Invention

The present invention relates to a vehicle wheel for supporting a pneumatic tyre.

Background to the Invention A pneumatic tyre and wheel assembly, when the tyre is inflated, forms an acoustically resonant toroidal cavity. In the case of automobile wheels the cavity frequency is in the region of 200Hz and standing waves, creating unwanted noise, are excited by driving the vehicle over certain types of road surface.

To reduce or eliminate the unwanted noise it is known to introduce noise absorbing assemblies into the tyre cavity. Conventional arrangements, however, tend to interfere with fitting a tyre to, or removing a tyre from, the wheel or might be easily damaged or displaced by the action of fitting a tyre. Also, any arrangement which lies against the interior circumferential surface of the tyre can interfere with operation of a liquid puncture repair product. Embodiments of the present invention address these problems.

Summary of the Invention

According to the present invention there is provided a vehicle wheel for supporting a pneumatic tyre, the wheel comprising a containing structure supporting and substantially enclosing a sound absorbing material such that fitting a pneumatic tyre to the wheel will not disturb or displace the sound absorbing material and such that the sound absorbing material is in fluid communication with a cavity defined by the wheel and the tyre when the tyre is fitted to the wheel. By providing the wheel with a structure to support sound absorbing material it is possible for the sound absorbing material to be mounted in a way which does not interfere with normal use of the wheel, in particular fitting and removing tyres from the wheel. The sound absorbing material may be a porous material and could be cellular, fibrous or granular. The sound absorbing material may comprise, or consist of, activated carbon.

The structure for supporting the sound absorbing material may be a cavity formed in the wheel. Where a wheel has spokes the cavity may be formed in a spoke. A cavity may be formed in more than one, or all, of the spokes of the wheel. The cavity may be a channel and the channel may extend around the periphery of the wheel. The wheel may comprise a horn portion where spokes or a disc connect to a rim and the cavity may be formed in the horn portion.

In other embodiments the structure comprises a flap of material extending from the wheel to define a pocket for accommodating sound absorbing material. The flap may be formed integrally with the wheel or formed separately and subsequently affixed to the wheel, such as by welding.

The structure may comprise a reservoir for housing sound absorbing material, the reservoir being mounted to the wheel. The reservoir may be formed by a container and may be connected to the wheel by a conduit such as a tube.

The structure may be arranged to contain the sound absorbing material. It may be formed separately to the wheel and subsequently fastened to the wheel. It may be fastened to a surface of the wheel which defines the cavity when a tyre is fitted to the wheel so that the sound absorbing material is exposed to the cavity. Alternatively, the structure could be mounted to an external surface of the wheel and a passageway provided through the wheel to fluidly connect the structure, and hence sound absorbing material, with the cavity defined by a wheel and tyre. In other embodiments the wheel, or wheel rim, is formed from two components which are fastened, for example, welded, together. The components are arranged so that when fastened together a cavity is formed between the two components and a sound absorbing material may be introduced into the cavity.

In other embodiments the structure comprises a channel formed in a surface of the wheel which forms a surface of the cavity defined by the wheel and tyre when a tyre is fitted to the wheel. The channel may extend completely around the periphery of the wheel and it may be formed in a substantially cylindrical surface of the wheel. Where a channel is provided the sound absorbing material may be comprised in a belt which is disposed in the channel. The belt may include stiffening members, such as ribs, to protect the belt when a tyre is fitted to the wheel.

Detailed Description of the Invention

In order that the invention may be more clearly understood embodiments thereof will now be described, by way of example only, with reference to the accompanying drawings, of which: Figure 1 shows a radial cross-section through a conventional vehicle wheel;

Figures 2 to 16, 19 and 20 show corresponding views of respective embodiments of vehicle wheels according to the invention; Figure 17 shows a perspective view of a belt for use with the wheels of figures 16, 19 and 20; and

Figure 18 shows an enlarged perspective view of a part of the belt of figure 17. Referring to the drawings, figure 1 shows a convention vehicle wheel for supporting a pneumatic tyre. An outline of a tyre 2 is shown in broken lines. The wheel comprises a hub 1 connected by spokes 3 (only one visible) to a rim 4. Flanges 5 are provided on respective opposite axial sides on the rim. The flanges are shaped to support the beads 6 of a tubeless pneumatic tyre 2 in order to support the tyre on the wheel. To fit the tyre 2 to the wheel 1 the tyre must be forced over rim 5 from one side of the wheel, so that one bead 6 of the tyre passes over the rim from one side to the other.

When the tyre 2 is inflated it forms an acoustically resonant toroidal structure, and resonant noise may built up in the structure when a vehicle is driven over certain road surfaces. This noise can be, undesirably, transmitted to the interior of the vehicle. To combat this noise, sound absorbing materials are introduced into the structure and, in particular, mounted to the wheel. Various embodiments of wheels with sound absorbing materials mounted thereto are now described. Each can be considered a modification of the wheel shown in figure 1. For convenience in what follows surfaces of the wheel which remain exposed when a tyre is fitted are referred to as outside surfaces and surfaces which are concealed by the tyre, and thus serve to form the toroidal cavity defined by the wheel and tyre, are referred to as inside surfaces. Also, the spoke side of the wheel, to the left in figure 1 , is referred to as the front of the wheel and the opposite side of the wheel as the back. Figure 2 shows a wheel with a hollow spoke 3. One, more or all of the spokes may be hollow. The spoke defines an internal cavity 7, which leads to an opening 8 on the inside surface of the wheel rim between the flanges 5 which lies within the tyre when a tyre is fitted to the wheel. Thus the interior of the cavity 7 is in fluid communication with the pressurised toroidal structure formed when a tyre is fitted to the wheel and inflated. A sound absorbing material 9 is disposed in the cavity 7. Any suitable material or combination of materials may be used. Porous materials are particularly suitable, and in particular materials comprising or consisting of activated carbon. Providing a sound absorbing material, particularly activated carbon, in fluid communication with the toroidal space inside a tyre fitted to a wheel has been found to successfully reduce resonant noise within the space. These sound absorbing materials may also be used in each of the embodiments discussed below.

Figure 3 shows an alternative wheel where a cavity 7 is formed in the wheel rim adjacent the end of a solid spoke 3, in the region of the wheel usually referred to as the horn. The cavity leads to an opening 8 on the inside of the rim. The cavity 7 may extend around the wheel rim forming a continuous channel in the rim, or there may be one or more discrete cavities. A sound absorbing material 9 is disposed in the cavity.

Figure 4 shows a variation on the wheel of figure 3. In this case the opening 8 into the cavity 7 is formed by one or more bores 8. This wheel has been cast with a material inside the casting which is later extracted to form the cavity 7. Bores 8 are drilled into the cavity 7 and sound absorbing material 9 introduced into the cavity through the bores.

Figures 5 and 6 shows a wheel where an additional flap of material 10 has been cast onto an edge (in this case the front edge, adjacent the spokes) of the wheel rim. The material extends a short distance towards the centre of the wheel rim and is spaced apart from the wheel rim in order to define a pocket between the flap 10 and the rim 4 in which a sound absorbing material 9 is disposed. The flap 10 and hence the pocket extend continuously around the periphery of the wheel. The flap 10 may be cast so that it extends generally parallel to the surface of the wheel rim as shown in figure 5 and formed from a material which may subsequently be deformed so that the free end of the flap can be moved nearer to the surface of the rim, as shown in figure 6. This reduces the size of the opening 8 via which the pocket communicates with the space inside a tyre fitted to the wheel and so helps to retain the sound absorbing material 9 in the pocket. Alternatively the flap may be left as shown in figure 5 or cast as shown in figure 6. The flap 10 allows a tyre 2 to be introduced over the wheel from (at least) the front side without interfering with the sound absorbing material.

Figure 7 shows a wheel similar to that shown in figure 6, except that the flap 10 has been welded to the wheel at point 11, rather than cast with the wheel. Figure 8 shows a modification to the arrangement of figure 7 where the flap 10 has been welded at point 11 to the substantially cylindrical mid part of the wheel rim rather than the built up, horn, part to which the spokes 3 are attached. For the wheels of both figures 7 and 8 the flap 10 enables a tyre to be fitted to the wheel without disturbing the sound absorbing material 9. Figure 9 shows a wheel fitted with a reservoir 12 of sound absorbing material.

The reservoir comprises a container containing sound absorbing material and is mounted to the wheel adjacent the wheel rim 4. The container 12 has an opening connected via a conduit 13 to an aperture extending through the wheel from an outside surface to an inside surface of the rim which will lie within a tyre when a tyre is fitted to the wheel. Thus, the interior of the container is in fluid communication with the toriodal space inside a tyre fitted to the wheel. The conduit may be formed by a length of tubing. One or more than one container may be provided. Multiple containers may be spaced around the wheel in order to ensure that the wheel is rotationally balanced.

Figure 10 shows a variation of the wheel of figure 9 where the container 12 is mounted adjacent the wheel hub and a longer conduit 13 is provided, extending from the wheel rim 4 to the container. Positioning the container at the wheel hub reduces the affect of the container on wheel balance. Figure 11 shows a wheel where a structure 14 comprising a sound absorbing material 9 is fastened to an inside surface of the wheel rim 4 by fasteners 15 such as bolts or rivets. An adhesive could be used to mount the structure instead of fasteners. The structure may extend around the circumference of the wheel rim, i.e. it may form a ring. Alternatively one or more discrete structures may be mounted to the rim. The structure 14 supports the sound absorbing material such that installation of a tyre to the wheel will not disturb or displace it. The structure could comprise a perforated metal envelope, or a suitably tough textile.

Figure 12 shows a variation to the wheel shown in figure 11. In this case the structure is mounted to outside if the wheel rim and one or more bores 8 are formed in the rim to provide a fluid communication between the interior of the structure 14 and the toroidal space inside a tyre fitted to the wheel. Clearly, in this embodiment, other than where it communicates with the bore 8, the structure 14 needs to be air tight. In particular it may have an air tight outer surface. Figure 13 shows a wheel where an elongate strip of metal 15 is welded to the outside of the wheel rim. The strip is welded to the wheel continuously along its edges 16 to form an air tight seal with the wheel, and is shaped to form a shallow channel which defines a space between the strip and the wheel in which a sound absorbing material 9 is disposed. Bores 8 are formed through the wheel rim to provide a fluid communication between the toroidal space inside a tyre fitted to the wheel and the space housing the sound absorbing material. The strip of metal 15 may form a ring and extend continuously around the surface of the wheel rim, or one or more discrete strips may be provided.

Figure 14 shows a modified version of the wheel shown in figure 13 where the strip of metal 15 is welded to the inside surface of the wheel rim. In this case the welds need not form an air tight seal, but in any event bores 8 are provided through the strip of metal so that the sound absorbing material 9 is in fluid communication with the space inside a tyre when fitted to the wheel.

Figure 15 shows a wheel where the wheel rim is formed by two components welded together. The two components are arranged so that when they are welded together along weld lines 17 a cavity 7 is formed. A sound absorbing material 9 is disposed into the cavity 7 and bores 8 extend from an inside surface of the rim to the cavity so that the interior space inside a tyre fitted to the wheel is in fluid communication with the sound absorbing material 9. The sound absorbing material could be introduced into the cavity through the bores, or applied to one component of the wheel rim before the components are welded together.

Figure 16 shows a wheel where the rim 4 is shaped to form a channel 18 which extends around the periphery of the inside surface of the rim. A belt 19 comprising a sound absorbing material runs in the channel. The thickness of the belt is approximately equivalent to the depth of the channel so that when the belt it fitted into the channel its exposed surface is generally flush with the inside surface of the wheel rim either side of the channel. The belt 19 is shown in greater detail in figures 17 and 18. The belt is endless and formed from a porous fabric material that allows air to flow through it but prevents any wear particles escaping into which a suitable sound absorbing material is introduced. A plurality of stiffening ribs 20 are spaced substantially evenly along the length of the belt, extending across the width of the belt. The stiffening ribs 20 serve to support a tyre as it slides over the belt when being fitted to the wheel and thus avoid the belt being damaged by the tyre.

Figures 19 and 20 show alternative embodiments of wheel similar to that shown in figure 16. Whereas in figure 16 the channel is formed generally mid-way across the width of the cylindrical part of the wheel rim in the embodiment of figure 19 it is formed towards the front (spoke side) of the rim and in the embodiment of figure 20 it is formed towards the rear of the rim.

In each embodiment a wheel is provided with a sound absorbing material which is mounted to the wheel in such a way that it does not significantly impede fitting a tyre to the wheel and so that the sound absorbing material will not be displaced or damaged when a tyre is fitted to the wheel. The above embodiments are described by way of example only. Many variations are possible without departing from the scope of the invention as defined in the appended claims.