GB2202196A - A wheel for a pneumatic tyre - Google Patents

Abstract

A wheel (11) for a pneumatic tyre, has rim flanges (26, 27) forming tyre bead seats separated by a circumferential well (21), and comprises a one piece cup-shaped body having a substantially planar bottom wall (15), a frusto-conical side wall (20), a rim (27) of which constitutes one of the rim flanges of the wheel, and a projecting annular frusto-conical flange (25) which extends from the side wall (20) to define the other rim flange (26). The flange (25) is reinforced by ribs (28) lying in respective diametral axial planes interconnecting the flange (25) and the portion (22) of the side wall (20) of the wheel body. Cooling apertures (30), Fig 1, are provided between alternate pairs of ribs (28). The wheel is a unitary casting of aluminium or aluminium alloy. <IMAGE>

Description

A WHEEJ, FOR A PNEUMATIC TYRE The present invention relates to a wheel for a pneumatic tyre and particularly, although not exclusively, to a wheel specifically adapted for use on commercial vehicles.

Commercial vehicle wheels have to withstand very considerable forces in use due to the loads which are imposed on them, and because of these and the safety considerations which have to be met there are very stringent regulations governing the construction of such wheels. This has resulted until now in the use of constructional configurations involving fabricated components of pressed steel which have been secured together by welding or bolting. Although unitary moulded wheel rims of lightweight alloy, particularly, aluminium alloy, have become very popular in the automotive field, it has not until now been possible to adapt this manufacturing technique to the production of wheels suitable for commercial vehicles because suitable designs exhibiting sufficient strength were not available.

The present invention seeks to overcome this problem by providing a vehicle wheel structure for a pneumatic tyre, suitable for use on a commercial vehicle, which can be integrally moulded from aluminium or an aluminium alloy and embodiments of which are capable of meeting the stringent requirements of the safety regulations imposed on commercial vehicle wheels.

It is known that wheels for pneumatic tyres comprise a pair of bead portions formed on circumferentially extending flanges which are axially spaced from one another and separated by a well portion of smaller diameter than the perimeter of the flanges, this well portion serving to receive the bead of the tyre upon assembly to enable the tyre to be fitted without excessively stretching the bead cores which are usually substantially inextensible filaments of metal wire or other suitable materials.

For use on commercial vehicles it is necessary for the rim to be provided with a generally planar attachment flange which, because of the dimensions of the wheel hub, is very often located out of the region defined by the two radial planes passing through the perimeters of the flanges, although motor car wheels generally have such a planar flange portion lying between these two planes.

This is one of the reasons for the necessity for the very considerable strength of a wheel intended for use on a commercial vehicle.

According to one aspect of the present invention, therefore, a wheel for a pneumatic tyre, having two axially spaced rim flanges forming bead seats separated by a circumferential well, comprises a monolithic substantially cup-shape body having a generally planar bottom wall, a frusto-conical side wall, a rim which constitutes one of the said rim flanges of the wheel, and a projecting annular generally frusto-conical flange which extends from the said side wall of the body to define the other of the said two rim flanges, the said projecting annular flange being reinforced by a plurality of ribs lying in respective diametral axial planes and interconnecting the said projecting annular flange and the portion of the frusto-conical side wall of the wheel body between the root of the said projecting annular flange and the bottom wall of the body.

The provision of these substantially radially extending ribs serves considerably to strengthen the structure such that a tyre carried by the bead seats defined by the rim flanges is accurately and securely located with respect to the planar flange defined by the bottom wall of the cup-shape body.

One of the problems encountered with commercial vehicles is that of overheating of the wheel hub, particularly during braking, and the wheel of the present invention provides means by which this problem can, at least to some extent, be alleviated in that there are provided a plurality of apertures in the said side wall between adjacent pairs of at least some of the said reinforcing ribs. The reinforcing ribs may, in fact, be grouped in pairs with a side wall aperture between each adjacent pair so that circumferentially around the wheel the wall portions between alternate adjacent reinforcing ribs are formed with side wall apertures. Needless to say, the other alternate portions are not pierced.

The reinforcing ribs preferably have a generally triangular profile with two adjacent sides of the triangle merging with the said projecting annular flange and the other with the side wall of the body, and having a free side joining,the two. This free side may be substantially rectilinear, but preferably is curvilinear to follow a generally ogee shape. Likewise, it is preferred that the said reinforcing ribs are thicker at their root portions than at their free sides, and join the side wall and annular flange portion with a radius of curvature of the same order as the curvature in cross-section at the free side of the rib.The bottom wall of the cup-shape body preferably has a concentric central aperture therein such that the said bottom wall is in effect constituted by a planar radially inwardly directed flange projecting inwardly from the narrow end of the frusto-conical side wall of the body. The bottom wall of the body also preferably has an annular array of fixing holes concentric with the rim and the said central aperture, through which bolts or studs are passed to fix the wheel to a wheel hub in a conventional manner. Such fixing holes must, of course, have a circumferential spacing such as to match that of the studs on the hub to which the wheel is intended to be fitted, and for this purpose the fixing holes preferably have an angular spacing of 360 and are equally spaced around the circumference of the planar flange defining the bottom wall of the cup-shape body.

As far as the apertures in the side wall of the cup-shape body, between adjacent pairs of ribs, is concerned, these preferably have an outline with generally parallel sides and curved ends. These apertures in the side wall preferably also extend into the corner portion where the bottom wall of the cup-shape body meets the frusto-conical side wall thereof, with the side wall of each aperture (that is the wall defined by the thickness of the material of the wheel) being inclined in the region of So to the normal to the local plane of the wall portion in which the aperture is formed. This feature is of importance for casting the wheel body, and as mentioned above it is preferred that the wheel body is integrally cast as a monolithic body from aluminium or an alloy thereof, although other metals may alternatively be used if desired.

The rim of the cup-shape body and the radially outermost edge of the projecting annular flange may each be provided with a circumferentially extending bulbous enlargement constituting a bead-retaining lip around the edge of the bead seat portion of the rim flange.

The projecting annular flange, although it has a substantially frusto-conical form, is preferably not of uniform cone angle throughout its axial extent, but has a radially inner root portion projecting substantially perpendicularly with,respect to the plane tangential to the local surface of the side wall of the body from which it projects, it being a rim portion of the flange which defines the frusto-conical surface: the cone angle of this frusto-conical surface substantially corresponds to that of the rim portion of the side wall of the body, but of course inverted through 1800 with respect thereto.

One embodiment of the present invention will now be more particularly described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a split side view the upper half of which shows the wheel of the invention from one side and the lower half of which represents the wheel of the invention seen from the other side; Figure 2 is a scrap section taken on the line II-II of Figure 1; Figure 3 is an axial section taken on the line III-III of Figure 1; and Figure 4 is a scrap view illustrating the outline of a side wall aperture when seen in the direction of the arrow IV of Figure 3, Referring now to the drawings, the wheel of the invention is generally indicated with the reference numeral 11 and comprises a monolithic integrally cast generally cup-shape rather deeply dished.wheel body having a flat bottom wall 12 and a generally frusto-conical side wall 13 meeting at an annular corner 14. The frusto-conical wall portion 13 does not have an equal cone angle throughout its length and will be discussed in greater detail hereinbelow. The planar bottom wall portion 12 is effectively constituted by an inwardly directed radial flange 15 the inner rim of which defines a central aperture 16 concentric with the flange 15 and the frusto-conical wall portion 13.Equally spaced around the radial flange 15 are ten fixing holes 17 the diameter of which is suitable to receive fixing bolts or studs on a wheel hub to which the wheel rim 11 is intended to be fitted.

The frusto-conical wall portion 13 has three main parts, namely a radially outer flange portion defining the rim 19 of the cup-shape body 11, an intermediate parallel-sided portion 20 defining a central well 21, and a radially inner portion 22 which joins the bottom wall 12 at the corner portion 14 as illustrated in Figure 3.

From the junction zone between the parallel-sided portion 20 defining the well 21 and the radially innermost portion 22 of the frusto-conical side wall 13 extends a projecting annular flange 23 having a root portion 24 and a frusto-conical rim flange portion 25 at the outer periphery of which is a bulbous ridge 26 constituting a bead retainer. The root portion 24 of the projecting annular flange 23 extends substantially orthogonally of the general plane defined at any point tangential to the radially inner frusto-conical portion 22 which is substantially aligned with the radially outermost frusto-conical flange rim portion 18, and the flange rim portion 25 of the projecting annular flange 23 lies at a cone angle which is substantially the same as that of the flange rim 18, but inverted through 1800.The flange rim 18 also has a bulbous annular projection 27 constituting a bead retainer and the inclined frusto-conical radially outer surfaces of the flange rim portions 18 and 25 constitute bead seats for receiving the beads of a pneumatic tyre to be fitted on the rim.

The radially inner face of the projecting annular flange 23 is supported at regular intervals around its circumference by a plurality of generally radially extending reinforcing ribs 28 which, as can be seen in Figure 3, have a generally triangular shape with two inclined straight sides merging with the radially inner frusto-conical portion 22 of the cup-shape body 13 and the projecting annular flange 23 respectively, and a free side 29 having a curvilinear ogee shape as can be seen in Figure 3.

Referring now to Figure 1, the ribs 28 can be seen each to lie in a respective diametral plane projecting in the manner of spokes from the centre 0 of the wheel body 11.

Between adjacent pairs of ribs 28 the radially inner side wall portion 22 of the cup-shape body 11 is pierced with apertures 30 the outline shape of which is illustrated in Figure 4. Here it can be seen that the apertures 30 have two parallel side walls 31, 32 joined at the radially outermost end, axially adjacent the root portion 24 of the projecting annular flange 23 with a substantially semi-circular curve 33, and joined at the radially innermost end by a curved surface 34 the generatrices of which lie approximately parallel to the axis of the wheel body 11, but at an angle in the region of 50 to exact parallelism with this axis as indicated in Figure 3.

These apertures 30 act to allow the passage of air from the outside towards the inner part of the cup-shape body 11 for cooling purposes in use of the wheel.

The ribs 28 taper in the axial direction from the root portion adjacent the root portion 24 of the projecting annular flange 23 towards a free side 29, as illustrated in Figure 2, and the free side is defined by a curve 35 joining the two inclined side faces 36, 37 of the rib 28.

At the root portion the rib 28 is joined by two curves 38, 39 on opposite sides thereof to the adjacent part of the wheel body 11. These ribs provide substantial support for the projecting annular flange 23 so that the wheel body 11 can be made as a unitary casting in aluminium or aluminium alloy and nevertheless meet the stringent requirements imposed on commercial vehicle wheels.

A smaller hole 40 in the root portion of the projecting annular flange 25 is provided to receive a filler valve for the tyre fitted on the rim.

Claims (14)

1. A wheel for a pneumatic tyre having two axially spaced rim flanges forming bead seats separated by a circumferential we)l. the wheel comprising a monolithic generally cup-shape body having a generally planar bottom wall, a frusto-conical side wall, a rim which constitutes one of the said rim flanges of the wheel, and a projecting annular generally frusto-conical flange which extends from the said side wall of the body to define the other of the said two rim flanges, the said projecting annular flange being reinforced by a plurality of ribs lying in respective diametral axial planes and interconnecting the said projecting annular flange and the portion of the frusto-conical side wall of the wheel body between the root of the said projecting annular flange and the bottom wall of the body.

2. A wheel as claimed in Claim 1, in which there are a plurality of apertures in the said side wall between adjacent pairs of at least some of the said reinforcing ribs.

3. A wheel as claimed in Claim 2, in which the reinforcing ribs are grouped in pairs with aside wall aperture between each adjacent pair so that circumferentially around the wheel wall portions between alternate adjacent reinforcing ribs are formed with side wall apertures.

4. A wheel as claimed in any preceding Claim, in which the reinforcing ribs have a generally triangular profile with two adjacent sides of the triangle merging one with the said projecting annular flange and the other with the side wall of the body, and having a free side joining the two.

5. A wheel as claimed in Claim 4, in which the said free side of each triangular rib is curvilinear, following a generally ogee shape.

6. A wheel as claimed in Claim 4 or Claim 5, in which the said reinforcing ribs are thicker at their root portions than at their free sides and join the side wall and annular flange portions with a radius of curvature of the same order as the curvature in cross section at the free side of the rib.

7. A wheel as claimed in any preceding Claim, in which the bottom wall of the cup-shape body has a concentric central aperture therein such that the said bottom wall is constituted in effect by a planar radially inwardly directed flange projecting inwardly from the narrow end of the frusto-conical side wall of the body.

8. A wheel as claimed in Claim 7, in which the bottom wall of the body has an annular array of fixing holes concentric with the rim and the said central aperture (360 spacing).

9. A wheel as claimed in any of Claims 2 to 8, in which the said apertures in the side wall between adjacent pairs of ribs have an outline with generally parallel sides and curved ends.

10. A wheel as claimed in Claim 9, in which the said apertures in the side wall also extend into the corner portion where the bottom wall of the cup-shape body meets the frusto-conical side wall thereof with the side wall of the aperture being inclined substantially at 5 to the normal to the local plane of the wall portion in which the aperture is formed.

11. A wheel as claimed in any preceding Claim integrally cast from aluminium or an alloy thereof.

12. A wheel as claimed in any preceding Claim, in which the rim of the cup-shape body and the radially outermost edge of the projecting annular flange each have a circumferentially extending bulbous enlargement constituting a bead-retaining lip around the edge of the rim and the flange respectively.

13. A wheel as claimed in any preceding Claim, in which the projecting annular flange has a radially inner root portion projecting substantially perpendicularly with respect to the plane tangential to the local surface of the side wall of the body, and a rim portion defining a frusto-conical surface the cone angle of which substantially corresponds to that of the rim portion of the side wall of the body but inverted through 1800 with respect thereto.

14. A wheel for a pneumatic tyre substantially as hereinbefore described with reference to and as shown in, the accompanying drawings.