GB2198094A

GB2198094A - A vehicle wheel fitted with a pneumatic tyre

Info

Publication number: GB2198094A
Application number: GB08725157A
Authority: GB
Inventors: Johannes Josef Baumhofer; Dionysius Poque
Original assignee: Uniroyal GmbH
Current assignee: Uniroyal GmbH
Priority date: 1986-10-29
Filing date: 1987-10-27
Publication date: 1988-06-08
Anticipated expiration: 2007-10-27
Also published as: FR2605937A1; GB8725157D0; IT8722309A0; GB2198094B; IT1222932B; IT8722552V0; DE3636782A1; FR2605937B1

Abstract

A vehicle wheel is fitted with a pneumatic tyre, having a radially outwardly directed tyre bead 7 in which a bead ring 4, Fig 1, is provided spaced from a bead seating surface 3 of the wheel by a distance a which is between one quarter and one third of the diameter of the bead ring. The bead ring 4 is rotatable relative to the surrounding bead material. When a tyre bead is in its axially outward position, shown in dash lines, the inside diameter of the tyre is increased facilitating mounting of the tyre on the wheel. <IMAGE>

Description

A VEHICLE WHEEL FITTED WITH A PNEUFATIC TYRE The invention relates to a vehicle wheel fitted with a pneumatic tyre. More particularly the invention relates to a vehicle wheel fitted with a pneumatic tyre and formed from a one-piece wheel rim and a pneumatic vehicle tyre, wherein the pneumatic tyre has a single-ply or multiple-ply carcase, more especially a radial carcase, and two tyre beads which are disposed with an axial lateral spacing therebetween and each have a respective, substantially inextensible bead ring, the bead base surfaces of the tyre beads being provided radially externally in relation to the bead ring, wherein the bead ring is eccentrically disposed in the bead, and wherein the wheel rim has two radially inner rim shoulders which have an axial lateral spacing therebetween and which merge into radially inwardly extending rim flanges.

Such a vehicle wheel is known from German Offenlegungsschrift No. 3 244 046. The wheel rim had radially inwardly extending rim flanges with seating surfaces on the radially inner circumference for the tyre beads. In order to permit a tyre of such type to be advantageously mounted on the rim without the provision of a mounting recess, the central diameter of the bead ring in the case.of this bead is adapted to be identical to, or slightly greater than the smallest diameter of the rim flange.

When the tyre is in its assembled state, the spacing from the centre of the cross-section of the bead ring to the radially outer bead boundary is greater than the spacing from the axially inner bead boundary. The bead ring is adapted to be rotatable and/or pivotable and is eccentrically displaceable.

This tyre construction necessitates a relatively high force being exerted to move the tyre bead over the rim flange for mounting purposes. In consequence, the lower lateral wall of the tyre is subjected to high tensile and compressive forces.

Such pneumatic vehicle tyres, which have bead seating surfaces on the inner circumference of the rim, can be assembled more advantageously when the method described in German Offenlegungsschrift No. 3 233 441 is utilised.

In this case, the wheel rim and pneumatic tyre are moved vertically towards each other and, in so doing, the rim is preferably introduced into the ovally expanded tyre.

Subsequently, the wheel rim is rotated through 900. In this position, the tyre beads are pressed onto their seats in succession according to the conventional mounting method and ready assembled.

In this transverse mounting method, the bead of the ovally expanded tyre is urged over the outer boundary surface of the rim with a certain amount of force. This makes wear inevitable at locations between the rim and tyre, especially when this method is accomplished by means of mechanical apparatus.

bear phenomena of this type should be totally avoided during mounting, or at least be kept to a minimum.

With a vehicle wheel fitted with a pneumatic tyre of the above-described type, therefore, the technical object of the invention is to construct the tyre bead in such a manner that a temporary enlargement of the oval expansion state of the tyre is hereby achieved, such enlargement simply being an additional mounting aid, whereby the abovementioned wear phenomena are kept at least small and considerably less force is required during mounting or assembly.

According to the invention, this object is achieved in that, with at least one of the two tyre beads, the bead core is provided with as small a radial distance as possible from the bead base surface, such distance corresponding substantially to one quarter to one third of the diameter of the bead core ring. In addition, the bead core is adapted to be rotatable relative to the bead material surrounding it, and the lateral wall of the tyre is adapted to be outwardly pivotable.

This disposition of the bead core in the tyre bead permits an incresse in diameter when the tyre bead is in its axially outwardly pivoted position. The amount of increase may be selected to be twice the difference which exists between the radial spacing of the bead core diameter relative to the bead base surface according to prior art and the comparable spacing according to the application which is now substantially reduced. Because of the rotatability of the tyre bead, the inner diameter in the outer pivoted position can be increased to such an extent that it permits a satisfactory transverse movement between the rim and tyre when the tyre is ovally expanded for the mounting of the tyre and rim.

In addition, the axial spacing between the bead ring and the corresponding axial bead configuration may also be relatively small. In this way, the bead core can be disposed almost in the wedge of the bead tip. In consequence, the spacing between the bead ring and rim flange is increased. This facilitates the mounting movement of the tyre bead over the inwardly protruding rim flange.

The present invention will be further illustrated, by way of example, with reference to the accompanying drawings, in which Fig. 1 is a partial cross-sectional view of a tyre having inwardly pivoted tyre beads on a wheel rim, shown in the operative state, and a pivoted position of a tyre bead is illustrated by dotted lines; Fig. 2 shows a detail of a bead region of Fig. 1; Fig. 3 shows the mounting position of a tyre and a rim of Fig. 1 during the transverse movement; and Fig. 4 is a side elevational view of the mounting position of Fig. 3.

According to Figs. 1 and 2, the pneumatic vehicle tyre 1 is provided with tyre beads 2 whose bead base surface 3 extends radially externally as the seating surface on the rim shoulders. The bead core 4 is disposed in the tyre bead 2 in such a manner that, because of a relatively large outer diameter Ukas it is disposed with as small a radial distance a as possible from the bead surface 3 as is permissible for structural reasons in respect of material strength. Furthermore, the axial spacing b from the bead configuration 7 is selected to be relatively small. The bead core 4 is adapted to be rotatable relative to the tyre bead 2, or vice versa.The spacings a and b each correspond to one quarter or one third of the diameter of the bead core 4; that is to say, for example, that, with a diameter of 7 mm, a corresponds substantially to 1.75 mm + a tolerance of 0.2 mm. With one third of the diameter, a corresponds substantially to 2.3 mm + a tolerance of 0.2 mm.

The wheel rim 10 has two rim shoulders 11 which are inclined at an angle d of substantially 50 and serve as the bead seating surface, and the wheel rim 10 is also provided radially externally. as the emergency running support 13.

The rim flange 12 extends radially inwardly. The smallest diameter of this rim flange is denoted by DH. The envelope curve, which occurs as an imaginary line above the rim cross-section, is denoted by Hk oval.

Due to the pivotability of the lateral wall 8 of the tyre about an imaginary resilient pivotal point, and due to the rotatability of the tyre bead 2 relative to its bead core 4, an inside diameter Dk can be obtained vith as small a spacing a as possible in the pivoted position K; cf. Fig. 2. This diameter is greater by an amount corresponding to twice the difference between the spacing a according to the bead of prior art (not shown) and the spacing a according to the proposal of the invention.

If, for example, the spacing a of a known bead between the bead core outside diameter and the bead base surface corresponds substantially to 5 mm, then, with a relatively small spacing a of 2.5 mm according to the proposal of the invention, the difference is around 2.5 mm. This figure applies to the upper and lower ends of the tyre bead and, in consequence, is around 5 mm. This figure;- multiplied by ff , produces an additional length of around 15 mm. The oval tyre opening is greater by an amount corresponding to this length compared with the present circumferential length of the rim according to the envelope curve Hk oval.

The mounting position of Figs. 3 and 4 shows how the pneumatic tyre 2 is urged transversely over the rim 10 with an ovally expanded tyre, or vice versa. In the illustrated pivoted position K of the tyre bead, there is an increased spacing Dk due to the proposed provision of the bead ring 4 with a very small spacing a. The length of the ovally expanded tyre K oval is, in this respect, substantially 15 mm longer than the circumferential length when measured over the rim cross-section. This means permits the rim to move transversely into the tyre for mounting purposes in an advantageous manner, that is to say substantially without the need for a high force to be exerted.

Claims

1. A vehicle wheel fitted with a pneumatic tyre and formed from a one-piece wheel rim and a pneumatic vehicle tyre, wherein the pneumatic tyre has a single-ply or multiple-ply carcase, more especially a radial carcase, and two tyre beads which are disposed with an axial lateral spacing therebetween and each have a respective, substantially inextensible bead ring, the bead base surfaces of the tyre beads being provided radially externally in relation to the bead ring, wherein the bead ring is eccentrically disposed in the bead, and wherein the wheel rim has two radially inner rim shoulders which have an axial lateral spacing therebetween and which merge into radially inwardly extending rim flanges, characterised in that, in the case of at least one of the two tyre beads, the bead core ring is provided with a small radial spacing from the bead base surface substantially corresponding to one quarter to one third of the diameter of the bead core ring, and the bead core ring is adapted to be rotatable relative to the bead material surrounding it.

2. A vehicle wheel fitted with a pneumatic tyre as claimed in claim 1, wherein the bead core ring is additionally provided with a small axial spacing from the bead configuration substantially corresponding to one quarter to one third of the diameter of the bead core ring.

3. A vehicle wheel fitted with a pneumatic tyre, substantially as hereinbefore described with reference to the accompanying drawings.