GB2199792A - Retaining tyre beads on wheel rim bead seats - Google Patents

Abstract

The tyre beads 2.1 of a wheel and tyre assembly are retained on bead seats 1.3 by securing means in the form of thin-walled resilient projections 4, 3.2 which can be pressed radially inwardly as far as the rim (1) without any plastic deformation. During the assembly when the two beads (2.1) of the tyre (2) are transferred from the drop base (1.1) to their seats (1.3), the projections (4, 3.2) are pressed towards the rim wall and are released again as soon as the beads have reached their seats (1.3) on the rim, so that the projections (4, 3.2) snap upwardly. <IMAGE>

Description

VEHICLE WHEEL, FITTED WITH A PNEUMATIC TYRE, HAVING A SECURED BEAD SEAT The invention relates to a vehicle wheel, comprising a one-piece rim with a drop base and a pneumatic tyre, the beads of which are supported radially externally on the rim, wherein securing means are provided in the region of the side walls of the rim drop base and prevent the beads from sliding axially inwardly in the event of the tyre travelling without compressed air. Such securing means are described in German Patent Specification No. 2 758 342. The idea there is that the securing means adopt their locked position only by the action of centrifugal force, but they can be easily unlocked when stationary.With a flat tyre, however, one will in fact be more inclined to travel slowly, and then the mechanism, which is actuated by centrifugal force, may fail in the case where there is advanced corrosion and hence a high level of friction.

moreover, the lock bolts, which are subject to bending and shearing during operation, are relatively heavy. In consequence, the unsprung masses are visibly increased and imbalance phenomena may result since the final positions of the lock bolts can be changed by wear which has occurred during the course of operation.

The invention seeks to keep the securing means light in weight and to avoid imbalance phenomena. Moreover, the securing means should not hinder the assembly of the tyre on the rim.

According to the invention, the object is achieved, in that the securing means are thin-walled, resilient projections which are raised radially outwardly at an angle (sot) which is small relative to the axis of rotation, and they can be pressed radially inwardly as far as the rim without any plastic deformation.

The projections, which are raised at a small angle and are preferably formed from sheet steel, are sufficiently resilient to permit the two beads of the tyre, during transfer from the drop base to their seating surfaces, to bend the proJections in a resilient manner radially inwardly towards the rim wall by the action of axial forces. The additional loading, which thereby occurs on the bead cores and seeks to expand the bead cores, is less than would be the case if such a large rim hump were to be overcome, which hump alone would actually prevent the bead from sliding axially inwardly, even if the tyre were travelling without any pressure. When the two tyre beads have reached their seating surfaces on the rim, they again release the resiliently inwardly bent projections, so that the latter are automatically raised.

The basic concept of the invention, therefore,resides in utilising resilient projections, which extend at a samll angle relative to the assembly direction, as securing means which produce a snap locking mechanism between the tyre and rim, which mechanism is positively actuated by the beads which are axially displaced at the end of the assembly process. The proposed projections are light in weight and do not change their position during the life of the tyre. In consequence, they cannot adversely affect the balance of the wheel. For the purpose of achieving a particularly simple tyre assembly process, the projections on one axial side are brought into the snap-ready position only after both beads - even from this side - are brought over the rim flange with the known, wobble-like movement and are situated above the drop base.

The delay in the snap readiness on one axial side can be achieved because, when the projections are secured to the rim, they have a form which largely abuts against the rim and are plastically bent upwardly only after both tyre beads are situated above the drop base. It is also possible, of course, to raise the projections on both sides only when both beads are situated above the drop base.

In order that, as described, the projections can be bent upwardly at all during wheel assembly, they must be formed from a plastically deformable material. Sheet steel and sheet aluminium are particularly suitable, but thermoplastically deformable plastics materials, having rubber-like elastic resilience, are also possible.

Another possibility resides in locking the projections of at least one side in a resiliently pre-tensioned state by means of clamps or similar means so that the projections closely abut against the rim until such time as both tyre beads are situated above the drop base. By removing or displacing the clamps, the projections are subsequently unlocked and they are then snap-ready. The plastic deformability of the projections is not necessary for this modification.

In order to prevent the edges from being pressed during the transfer of force from the axially internal surface of the beads to the projections, the ends of the projections are advantageously upwardly radially externally) chamfered and rounded. Upon upward displacement, the projections traverse a predetermined, circular sector-like area when viewed in cross-section. The pneumatic tyre is advantageously provided on the axially internal surfaces of its beads with appropriate recesses, whereby a lack of clearance between the projection end and inner wall of the tyre is achieved. The final position of the projections may be defined by a shoulder portion, which defines the recess, on the tyre.

There are various possibilities for securing the projections on the rim. The minimum weight results when the projections are directly welded in position in the rim base, e.g. by spot-welding. However, the projections may also be secured indirectly when a ring, carrying the projections, is secured in the rim base. Such a ring transfers radial and axial forces to the rim in a form-fitting or positive manner and transfers circumferential forces - which are only minimally caused by braking and accelerating - in a frictionlocking manner. This ring is advantageously characterised in that it is a one-piece, thin-walled structure with a substantially U-shaped cross-section and, at its two axial edges, it has collars which extend substantially axially and from which the resilient projections extend, that is to say, the projections are integrally connected to the securing ring at their bases.

The ring is advantageously formed from only one curved, finitely long profile strip having one joint. The strip does not need to be formed from a plurality of parts since, as a general rule, it has only a minimal rigidity and can surmount the rim flange by means of slight, resilient torsion. The joint, whereby the strip is joined to form the ring, has to withstand considerable forces - occasioned by centrifugal forces - in the circumferential direction.

The joining process may be effectEd by adhesion or by formlocking, for example with a snap closure. The (possible) point of adhesion is advantageously not perpendicular to, but at an acute angle relative to the circumferential direction. In consequence, a sufficiently large, tangentially stressed adhesive area can be achieved without any overlapping, which would otherwise'cause a certain amount of imbalance.

On the other hand, a form-locking connection has the advantage that, if necessary, it can be disconnected in a particular simple manner. This simplifies the recommended, simultaneous replacement of the securing ring whenever the tyre is changed.

The securing ring, together with its integrally connected projections, can be manufactured in a particularly economical manner when it has a uniform wall thickness; in order that the projections are sufficiently resilient for the radial snap effect according to the invention, the wall thickness has to be thin. On the other hand, the projections do not need to absorb axial forces to a substantial extent in order to permit the tyre to be securely retained on the rim. The axial rigidity required therefor at the projection bases is achieved when the collars are supported in a formlocking manner relative to the rim.For this purpose, according to an advantageous embodiment of the invention, in the case of rims with a hump, the collars of the securing ring cover the respective hump in a flush manner and grip behind the axially outer walls of the hump in a form-locking manner. In the case of rims without a hump which permit a particularly simple assembly of the tyre, the corresponding effect can be achieved when the rim is provided with a groove, which is open towards the rim base, in each of the axially internal edges of the bead seating surfaces in which each of the collars of the securing ring engages in a form-locking manner with a respective chamfer.

The present invention will be further illustrated, by way of example, with reference to the accompanying drawings, in which: fig. 1 is a cross-sectional view of a vehicle wheel according to the invention, the wheel being provided, on the left-hano side, with projections secured directly on the rim and, on the right-hand side, with a securing ring carrying the projections; Fig Ia is a cross-sectional view showing a detail of a particular means for anchoring the ring collars in the rim; ri. 2 is a perspective view of a securing ring on its own, which has not yet been joined; and Fig; 3 is a schematic illustration of six cross-sectional views of the assembly procedure, starting with a rim having securing projections and a pneumatic tyre and ending with the finished vehicle wheel.

The vehicle wheel shown in ig. 1 is formed from a pneumatic tyre 2 and a rim 1, the rim 1 either being provided directly with securing projections 4 - as shown on the left-hand side - or accommodating a securing ring, carrying the projections, in its drop base - as shown on the right-hand side. The rim 1 is a one-piece structure and is identical to the currently conventional, mass-produced rims apart from the projections and/or the securing ring. It has a drop base 1.1 which facilitates assembly of the tyre beads 2.1 over a rim flange 1.2. To accommodate the beads 2.1, the rim 1 has bead seating surfaces 1.3 which are both axially inwardly defined by a respective hump 1.4. The entire structural area between the rim flanges 1.2 is referred to as rim base 1.5.

In the embodiment shown in the left half of the drawing, the projections 4 are individually welded to the rim 1. The weld abuts against the axially internal surfaces of the walls 1.7 of the rim drop base 1.1. In the embodiment shown in the right half of the drawing, a thin-walled securing ring 3 is supported in the rim drop base 1.1 in an axially nondisplaceable manner and has a collar 3.1 on each of its axial edges. The collars 3.1 surround the humps 1.4 in a flush manner and thereby prevent the projection bases 3.21 from being displaced axially inwardly when axial forces are introduced into the tyre 2.The ends 4 2 and 3.22 of the projections 3.2 are curved slightly upwardly and are rounded at all the edges in order to prevent excessive pressures and edge tensions from occurring at the location on the projection and bead where the forces are. introduced; in particular, the internal surface of the tyre is thereby prevented from being damaged by cuts due to the projections 3.2.

The invention permits all commercial tyres'two be so well secured on the rim that they cannot spring from the rim, even when the tyre is travelling without pressure. A favourable steering behaviour, which is also important during emergency running, is achieved when the internal surfaces of the tyre beads 2.1 have a particular configuration. The configuration corresponds to the circular sector-like path of movement of the projection ends 4.2 and 3.22. Hence, the beads 2.1 have axially internally, in the cross-section, a circular sector-like recess 2.2 which is upwardly (that is to say, radially outwardly) defined by the thickened portion 2.3 and determines a final position for the projections 4 and 3.2 after they have snapped in position.

Fig. la is a view showing a detail of another meats of anchoring the securing collars 3.1. The bead seating surfaces 1.3 are each defined axially inwardly by a respective circumferential rim groove 1.6. The collars 3.1 of the securing ring 3 are downwardly (radially internally) chamfered at the location where they are not raised as projections; these chamfers 3.5 engage in the rim groove 1.6 and provide a secure form-fit which is rigid relative to axial forces.

Fig. 2 is a perspective view of a profile strip 3.3 on its own. By utilising its bending and torsional resilience, which entails the thin-walled configuration, the strip can be mounted in the rim and joined to form the endless ring.

An adhesive joint is provided in this embodiment. For this purpose, the joint 3.4 extends inclinedly at an acute angle relative to the circumferential direction, whereby it (3.4) achieves a large area which is to be wetted by adhesive.

In addition, the inclined position causes the layer of adhesive to be substantially tangentially stressed, where good tensile values are to be achieved, and the layer is rarely stressed directly.

The projections 3.2, which extend from the left-hand collar (3.11) of the two collars 3.1, are held by clamps 3.12 in a low position. The tyre assembly from the left-hand side is thereby facilitated. After removal of the clamps 3.12 or after their displacement - as shown in the top lef-hand corner - the projections 3.2 are again in a raised position and are hence snap-ready.

The ring has ten projections 3.2 on each side, whereby the ring can absorb axial forces in a uniformly distributed manner. The maximum structural volume on the ring 3 is occupied by its U-shaped central portion which, in respect of its configuration, is adapted to the drop base of the rim provided. In its centre, it has at least one hole for-the passage through which the valve can pass; to save weight, a plurality of hole or bores may also be provided in the central region.

Fig. 3 is a schematic illustration of six successive cross-sections a to f, showing the assembly of a pneumatic vehicle wheel according to the invention. The securing projections are actually provided in the rim, and it is immaterial whether they are directly secured in the walls of the rim drop base or whether they extend from a ring.

Fig 3a shows the tyre and rim prior to assembly. The arrow indicates that the tyre is to be mounted from right to left, commencing with the left-hand bead. The assembly direction in such a case is arbitrarily determined. To simplify assembly, it is advisable for the projections not to be raised on the side from which the tyre is to be mounted, as indicated here at the right-hand projection.

In Fig. 3b, the left-hand tyre bead has reached the rim base. The arrow indicates that the right-hand tyre bead is now to be brought into the rim base in identical manner.

In Fig. 3c, the left-hand tyre bead has also reached the rim base. The arrow shows that the right-hand projections are raised into their snap-ready position as the next step. This may be effected by plastic distortion or by detaching any arresting means which have held down the projections in a resiliently tensioned manner. such as is shown, for example, in Fig. 2. The method of raising the projections by loosening arresting means is particularly advantageous when the projections are part of a securing ring formed from a plastic non-deformable plastics material.

In Fig. 3d, the projections are snap-ready on both sides.

The beads have next to be brought axially outwardly in the direction of their rim seating surfaces. For this purpose, air is pumped into the tyre interior, as shown by the arrows.

Fig. 3e shows the tyre beads at the halfway stage.

Because of their substantially inextensible and tensionresistant cores, the beads can scarcely expand radially outwardly. Instead, they bend the projections which extend at a small angle relative to the axial direction, resiliently inwardly by the effect of axial forces. To avoid friction, it is advisable to provide also a sliding means axially internaliyon the projections. The arrows indicate that the tyre is to be pumped-up further in order to move the beads further.

In Fig. 3f, the beads have reached their final position on the seating surfaces and have simultaneously released the securing projections. The projections are automatically snapped upwardly and, in consequence, the assembly of the vehicle wheel is concluded.

Irrespective of the particular embodiment, the basic concept of the invention is that, in the interior which is inaccessible when the wheel is finished, a bead locking system is achieved in such & manner that the energy required for the operation is stored in a resilient deformation, and this energy is both supplied and finally released through the bead movement.

Claims (10)

1. A vehicle wheel, comprising a one-piece rim with a drop base and a pneumatic tyre, the beads of which are supported radially externally on the rim, wherein securing means are provided in the region of the. side walls of the rim drop base which presents the beads from sliding axially inwardly in the event of the tyre travelling without compressed air, wherein the securing means are thin-walled, resilient projections which extend radially outwardly at an angle (or'), which is small relative to the axis of rotation and they can be pressed radially inwardly as far as the rim without any plastic deformation.

2. A vehicle wheel as claimed in claim 1, wherein the projections are formed from sheet steel.

3. A method of producing a vehicle wheel as claimed in claim 1, wherein the projections on one axial side, from which the tyre is to be mounted, are raised only after the transfer of both tyre beads into the rim base by plastic upward bending or by unlocking from a resiliently pre-tensioned state.

4. A method of assembling a vehicle wheel as claimed in claim 1, wherein the two beads of the tyre, upon transfer from the drop base to their seating surfaces, resiliently bend the projections, which extend at a small angle, radially inwardly towards the rim uall by the action of axial forces and release them again once they have reached their seating surfaces, so that the projections are automatically raised at the end of the assembly process.

5. A vehicle wheel as claimed in claim 1, wherein th pneumatic tyre is provided with circular sector-like recesses on the axially internal surfaces of its beads.

6. A vehicle whaglas claimed in claim 1, comprising in addition to a rim and a pneumatic tyre - a securing ring which is disposed in a clearance-free manner in the rim drop base, wherein the securing ring is a one-piece, thin-walled structure with a substantially U-shaped crosssection, and is provided, on its two axial edges, with collars which extend substantially axially and from which the resilient projections extend, that is to say the projections are connected integrally with the securing ring at their bases.

7. A vehicle wheel as claimed in claim 6, wherein the securing ring is formed from only one curved, finitely long profile strip having 2 joint.

8. A vehicle wheel as claimed in claim 6, wherein the projections at least of one ring collar of the two ring collars are held in a non-extended position by means of clamps and, after the arresting means has been loosened, they are raised by elastic spring-back resilience.

9. A vehicle wheel as claimed in claim 6, the rim of which has a respective hump for the axially internal definition of each of the bead seating surfaces, wherein the collars of the securing ring cover the respective hump in a flush manner, and the collars are prevented from being displaced axially inwardly because they grip behind the axially outer walls of the respective hump in a form-locking manner.

10. A vehicle wheel, as claimed in claim 1, which has a rim without a hump, wherein the rim is provided with a respective groove which is open towards the rim base at the axially internal edges of the bead seating surfaces, in which the collars of the securing ring engage in a form-fitting manner with a respective chamfer and thus prevent the collars from being axially inwardly displaced.