This invention relates to a wheel for a pneumatic tyre for use on a vehicle such as an automobile.

A typical wheel for a pneumatic tyre has a rim providing a well extending circumferentially around the wheel, the parts of the rim bounding the well axially providing bead seats to support the beads of a pneumatic tyre fitted to the wheel, and further providing bead retaining flanges extending from respective said bead seats away from the axis of the wheel.

In some wheel constructions one or both bead seats are formed with a raised rib which acts to hold the tyre bead on the bead seat even when the tyre is deflated. These wheel rim constructions are commonly known as "safety rims".

When a vehicle having such known wheels fitted with pneumatic tyres is in motion loss of steering control is often experienced if a tyre, particularly a tyre on a front or steered wheel becomes deflated. This loss of control may occur suddenly as a result of a tyre blow-out, or it may occur gradually if the tyre pressure is gradually reduced due to a puncture. When the tyre losses pressure the vehicle may tend to tilt to that side of the vehicle on which the puncture occurs so that the wheel bearing the tyre which has been punctured also tilts in the same fashion thus greatly affecting the steering geometry of the vehicle, reducing steering control and allowing only minimum use, if any, of the braking system to bring the vehicle to a halt.

The preferred embodiment provides an improved construction of vehicle wheel which substantially avoids the above stated disadvantages.

According to the invention there is provided a wheel for a pneumatic tyre, for use on a vehicle, comprising a rim having a well, bead seats and bead retaining flanges extending from respective said bead seats away from the wheel axis, one said bead retaining flange including a first portion extending substantially radially from the respective bead seat to a second portion which, in axial section through the wheel, bends away from an imaginary plane passing through the well and perpendicular to the wheel axis, a third portion which extends from the second portion and at a greater angle relative to the wheel axis than the adjoining part of said second portion, and a fourth portion extending from the radially outer part of said third portion and disposed further from the wheel axis than said second portion, said fourth portion, in axial section through the wheel, curving arcuately away from said imaginary plane passing through the well, said fourth portion providing a radially outwardly facing ground engaging surface which is of greater diameter by about at least 678 ^th inch than the other bead retaining flange.

The wheel rim is preferably made as an integral unit and roll-formed as is known in the art. Alternatively, the wheel may be cast and machined, as is also known in the art.

In one form of wheel embodying the invention, said first part of said one bead retaining flange extends substantially radially outwardly from the respective bead seat and said second, third and fourth parts are integral with said first part. In another form of wheel embodying the invention, said first and second portions of said bead retaining flange are provided by a wheel body portion and said third and fourth portions of said bead retaining flange are provided by a member releasably secured to the wheel body portion.

The member which provides said third and fourth portions of said one bead retaining flange may be secured to the wheel body portion by bolts or the like.

Embodiments of the invention are described below with reference to the accompanying drawings, wherein:-

Figure 1 is a view, in axial section, of a known vehicle wheel with a pneumatic tyre thereon in a deflated condition;

Figure 2 is a view, in axial section, of a wheel embodying the invention with an inflated pneumatic tyre thereon;

Figure 3 is a view similar to Figure 2 but showing the wheel with the tyre deflated;

Figure 4 is a fragmentary axial sectional view of another wheel embodying the invention;

Figure 5 is a fragmentary axial section view of a variant of the wheel of Figure 4 showing less of the wheel than is shown in Figure 4 but to a larger scale; and

Figure 6 is a fragmentary axial section view of yet a further embodiment of the invention.

Referring to the drawings, Figure 1 illustrates the result of a blow-out or puncture in a tyre 5 on a known wheel 4 which comprises a rim within which is fixed a circular diameticrally extending wheel disc 18, the rim providing inboard and outboard bead seats and inboard and outboard bead retaining flanges respectively extending from respective said seats away from the wheel axis, and in which the inboard and outboard bead retaining flanges are both of the same outer diameter. When the tyre 5 deflates, the vehicle supported by the wheel 4 tilts, thus causing the wheel camber angle of the wheel bearing the deflated tyre to increase. The weight of the vehicle is thus carried on the outboard bead retaining flange 6.

In the known wheel construction shown in Figure 1, the wheel disc 18 is arranged so that a vertical line passing through the point, in the area of contact of the tyre 5 with a road surface 11, which is the centre of force exerted by the tyre on the road, passes as close as possible to the wheel pivot member, for example the king pin 7. However, when the tyre 5 is deflated and the vehicle weight is transferred to the outer rim 6 of a vertical line passing through the centre of force exerted by the wheel on the road is substantially spaced from the wheel pivot thereby producing considerable strain on the wheel suspension parts resulting in excessive leverage on the steering linkage.

Figures 2 and 3 illustrate one embodiment of the invention wherein a wheel 8 includes a rim and a circular diametrically extending wheel disc 18 fixed within the rim, the rim having a well 12, an inboard and an outboard bead seat supporting inboard and outboard beads of a pneumatic tyre 5 and inboard and outboard bead retaining flanges and 6 respectively extending away from the wheel axis from the inboard and out-board bead seats respectively. The flanges 10 and 6, naturally extend around the entire circumference of the wheel the flange 6 extending substantially radially from its bead seat and having its radially outer edge rolled over, away from the well, to provide a bead. The flange 10 includes a first portion, for engagement with the respective tyre bead, which extends substantially radially outwardly from the inboard bead seat, a second portion, extending from said first portion and over which the flange, in axial section through the wheel, bends away from an imaginary plane passing through the well and perpendicular to the wheel axis, a third portion, extending from said second portion and in which the bead retaining flange extends at a greater angle relative to the wheel axis than the adjoining part of said second portion, and a fourth portion, formed by rolling the free edge of the flange over in a manner similar to the edge of the flange 10 over in a manner similar to the edge of the flange 6, which fourth portion is thus disposed further from the wheel axis than said second portion and, in axial section, curves arcuately away from said imaginary plane passing through the well and perpendicular to the wheel axis to provide a radially outwardly facing ground engaging surface 14 of greater diameter than the flange 6.

It will be appreciated that the wheel rim is formed integrally the part providing the well 12 and the inboard and outboard bead seats, the flange 6 and the said, first, second, third and fourth portions of the flange 10 all being integral with one another.

The third portion 9 of flange 10 and the fourth portion extending from said third portion are spaced from the inflated tyre 5.

As shown in Figure 3, if the tyre 5 becomes deflated, the weight of the vehicle is supported via surface 14 by fourth portion extending from portion 9 of flange 10. The wheel 8 does not, therefore, tilt to any appreciable extent and the vehicle is supported at a point which is inboard of the wheel pivot 7 so that no additional strain or leverage is placed on the wheel suspension and steering linkage. The vehicle can therefore be steered normally without loss of control and further the vehicle brakes may be used to bring the vehicle to a stop.

Referring to Figure 4, there is illustrated a further embodiment of the invention in which the inboard bead retaining flange is, in effect, of composite construction, a radially inner part being provided by a wheel body portion and a radially outer part being provided by a member 21 releasably secured to the wheel body portion.

The wheel body portion has substantially the same form as the known wheel of Figure 1 and includes a rim 22 having fixed within it a circular diametrically extending wheel disc 24. The member 21 has the form of a plate which fits against the side of the wheel body portion which is presented inwardly towards the vehicle when the wheel is fitted to a vehicle, the plate being so formed that its surface nearer the wheel body portion fits snugly against the opposing surface provided by the wheel disc 24, one half of the radially inner surface of the part of the rim which defines the bottom of the well in the rim, and the outer side of the part of the rim providing the inboard side of the well and the inboard bead seat.

The detachable plate 21 is preferably secured to the wheel body portion by means of the inboard bead seat.

The detachable plate 21 is preferably secured to the wheel body portion by means of a plurality of bolts passing through the wheel disc 24 and that part of plate 21 which engages the wheel disc 24.

The part 23 of the inboard bead retaining flange which corresponds in shape to the outboard bead retaining flange includes a first portion which extends substantially radially outwardly from the inboard bead seat and a second portion, in the form of an outwardly turned lip part which, in axial section, bends away from an imaginary plane passing through the well and perpendicular to the wheel axis and which bears upon a peripheral flange provided by the plate 21, the part of the last-mentioned flange extending outwardly beyond said outwardly turned lip part constituting a third portion of the inboard bead retaining flange and extending outwardly to a fourth portion which, in axial section, curves arcuately away from said imaginary plane passing through the well of the rim perpendicular to the wheel axis to provide, as before, a radially outwardly facing ground engaging surface providing the periphery of the inboard bead retaining flange and of greater diameter than the out- board bead retaining flange.

It will be noted that said peripheral flange provided by the plate 21 is offset, relative to the part of the inboard bead retaining flange provided by the wheel body portion away from said imaginary plane.

Referring to Figure 5 of the drawings, a modified form of the wheel of Figure 4 is illustrated, which differs from the wheel of Figure 4 in that a circumferential groove is formed on the side of the plate 21 which engages the opposing surface of the wheel body portion, to receive a sealing member such as an O-ring. The provision of the sealing member facilitates separation of the parts after they have been assembled for a long period.

It will also be seen in Figure 5 that the peripheral flange provided by plate 21 does not closely follow the configuration of the first portion, provided by part 23 and forming the radially inner part of the bead retaining flange but engages against only the outer edge 26 of said second portion provided by part 23.

The radially outwardly facing ground engaging surface at the periphery of plate 21 is of greater diameter, by at least 6/8 ^lh inch (i.e. 3/8 ^lh inch lip on either side of the wheel), than the outer edge 26 of bead retaining flange 23. Typically, the radially outwardly facing ground engaging surface at the periphery of plate 21 is of greater diameter, by less than 2 inches (i.e.

1 inch lip on either side of the wheel), than the outer edge 26 of bead retaining flange 23.

A further embodiment of the invention illustrated in Figure 6 is similar to that of Figure 4 and differs only in the form of a member 36 which replaces member 21 in Figure 4.

Thus the embodiment of Figure 6 includes a wheel rim 30 with inboard and outboard flange formations 32 and 31 respectively extending on either side of a wheel well 33 and further includes a wheel disc 35.

The member 36 includes a flat, radially extending inner central part secured to the wheel disc 35, a skirt 37 flaring frustoconically outwardly from said central part in the direction away from the wheel disc 35, and a peripheral flange 34, corresponding to that of plate 21, which extends radially outwardly beyond, and is engaged by, the outwardly turned peripheral lip of flange formation 32 in the same manner as in the embodiment of Figure 4, the flange 34 again being turned outwardly at its periphery to provide a radially outwardly convex ground engaging surface.

In use, if a tyre on the wheel becomes deflated during use of the wheel on a vehicle, the weight of the vehicle is supported on the outer edge of the flange 34. The wheel does not, therefore, tilt to any appreciable extent due to the tyre deflation and the vehicle is supported at a point which is generally inwardly of the pivot point of the wheel so that wheel suspension and steering linkages are not subjected to substantial additional strains or leverage. The vehicle can therefore be steered normally without loss of control and further the vehicle brakes may be used without danger to bring the vehicle to a stop.

Furthermore the wheel construction described with reference to Figures 2 to 6 do not lead to any increase in difficulty in tyre changing as compared with known wheels.