GB1563095A

GB1563095A - Tyre and rim assemblies

Info

Publication number: GB1563095A
Application number: GB39069/75A
Authority: GB
Original assignee: Dunlop Ltd
Current assignee: Dunlop Ltd
Priority date: 1975-09-24
Filing date: 1975-09-24
Publication date: 1980-03-19
Also published as: CA1064076A; FR2325522A1; IT1074023B; FR2325522B1; JPS5264702A; AU1783876A; FI762723A; ES451791A1; DE2643116A1; BE846362A; AU497793B2; JPS592642B2; SE7610417L; LU75841A1

Description

(54) IMPROVEMENTS IN TYRE AND RIM ASSEMBLIES (71) We, DUNLOP LIMITED, a British Company of Dunlop House, Ryder Street, St. James's, London, S.W.1., do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to improvements in wheel rims and tyre and wheel rim assemblies, the rims being of the well base type.

There has previously been proposed, in our U.K. Patent Specification No. 1 359 714, an assembly having a rim in which is provided adjacent one bead seat a circumferential recess or notch and a tyre having on the bead a toe portion which is extended into a radially or substantially radially inwardly directed annulus comprising elastomeric material.

The annulus rests freely in the recess and the cross-section and shape of the extended toe and notch are such that the toe may be compressed into the notch upon tilting of the bead under the influence of lateral forces on the tyre whereby the bead is restrained from movement axially across the wheel rim.

The present invention has the object of providing an additional safety means for the above mentioned assembly so as to provide a wheel and tyre assembly having a well to allow tyre fitting.

According to a first aspect of the present invention a tyre and rim assembly comprises a pneumatic tyre mounted on a wheel rim furnished with peripheral tyre bead retaining flanges, inboard and outboard tyre bead seating portions and a well between said bead seating portions, a first annular radially inwardly extending recess being formed adjacent the axially inner edge of the outboard bead seating portion to accommodate a radially inwardly extending annular extension of the toe portion of the associated tyre bead when the tyre is normally seated on the rim the extension resting freely in said first recess and the extended toe and recess each being of cross sectional shape and size which permits said toe to be compressed into said first recess upon tilting of the bead under the influence of lateral forces on the tyre whereby said bead is restrained from movement axially across the rim, and a second annular radially inwardly extending recess formed in the rim, the rim having a substantially flat ledge (as viewed in axial crosssection) disposed between said first and second annular recesses, and said first and second annular recesses being disposed between the outboard bead seating portion and the well.

According to another aspect of the present invention a wheel rim for a pneumatic tyre and wheel rim assembly according to the first aspect of the invention comprises peripheral tyre bead retaining flanges, inboard and outboard tyre bead seating portions and a well positioned between said seating portions, the rim having first and second radially inwardly extending recesses said first recess being disposed adjacent the axially inner edge of the outboard bead seating portion, the rim having a substantially flat ledge (as viewed in axial cross-section) disposed between said first and second annular recesses, and said first and second annular recesses being disposed between the outboard bead seating portion and the well.

The terms "inboard" and "outboard" used with reference to the tyre bead seating portions of wheel rims of this invention are with reference to the disposition of the wheel rim in use on a vehicle.

Instead of said second annular recess disposed inboard of the ledge there can be used in the first or second aspects of the invention two or more such annular recesses. The axially inner or innermost of the recesses is preferably positioned adjacent the axially inner edge of the ledge and merges into a wall of the well. In the latter arrangement the axially inner edge of the inner or innermost annular recess and the axially outer wall of the well preferably together form a hump which extends axially outwardly of the ledge.

The cross-sectional profile of the recesses may be of any profile which will satisfactorily accommodate the bead toe extension of the adjacent tyre bead, such as 'U' shaped or 'V' shaped profiles; it is preferably sufficiently rounded to enable it to be formed in the rim body by a process of rolling.

The inner recess or recesses may be of asymmetric section so that the tyre bead is more positively engaged in the recess. In addition the axially outer surface of the inner recess or recesses may have a more gentle slope than the axially inner surface to assist movement back of the bead toe extension towards the first recess.

The axially inner edge of the inboard tyre bead seating portion may be provided with a radially outwardly extending abutment which serves to restrain axial inward displacement of the inboard tyre bead.

An embodiment invention will now be described by way of example only and with reference to the accompanying drawing in which is a cross-sectional diagrammatic view of part of a tyre and rim assembly showing the outboard bead in a first position where the bead is normally seated on its seating portion of the rim and in a second position where the beat has been axially displaced from said seating portion.

As shown in the drawing a tyre and rim assembly comprises a rim 1 having peripheral bead retention flanges 2 and 3 bounding outboard and inboard seating portions 4 and 5 respectively for the beads 7 and 8 of an associated pneumatic tyre 9. The beads 7 and 8 are reinforced with substantially inextensible cores 10 and 11 respectively. The rim 1 is also provided with a well portion 12 positioned adjacent the inboard bead seating portion 5.

A flat cylindrical ledge 13 (flat when viewed in axial cross-section) is positioned between the well 12 and the outboard bead seating portion 4. At the axially inner edge of the outboard bead seating portion 4 there is provided an annular radially inwardly extending recess 15 of substantially 'U'-shaped profile when viewed in axial cross-section. The recess 15 is arranged to accommodate an annular extension 16 of the toe 17 of the outboard tyre bead 7 when seated on the associated bead seat 4.

Spaced axially from the first recess 15 and positioned at the axially inner edge of the flat ledge 13 is a second annular recess 20 of substantially 'U'-shaped cross-section, the axially inner wall 21 of which merges with a radially outwardly extending wall portion 22 of the well 12. The axially inner wall 21 and wall portion 22 define an annular hump 23 which extends radially outwardly to a diameter greater than the diameter of the flat ledge 13.

The axially inner edge of the inboard bead seating portion 5 is provided with a radially outwardly extending abutment 25 which acts to restrain axial inward displacement of the inboard tyre bead 8.

When the tyre 9 is normally seated on the wheel rim the extension 16 of the bead toe extends into the first axially outer, recess 15 so that in the event of the tyre becoming deflated in normal useage and the tyre being subjected to a lateral force, the bead tends to tilt so that the bead toe is compressed into the recess, the compressive force within the recess resists the tilting of the bead and thus restrains the outboard bead 7 from being totally displaced. With the bead toe extension 16 located in the first recess 15 the bead can, in some circumstances, be displaced from its associated seat 4 onto the ledge 13 but the bead toe extension remains within the recess and eventually the bead returns to its normal seating position.

The above location of the bead is described in greater detail in our U.K. Patent Specification No 1 395 714.

However, in conditions of high lateral force such as some accident avoidal manouvres the outboard bead may become dislodged completely from the recess 15 and moves across the ledge 13. The second recess 20 is positioned at the axially inner edge of the ledge 13 and so, when the outboard bead 7 is displaced from the first recess 15 the bead 7 engages the second recess 20.

Furthermore the radially outwardly extending hump 23 assists in restraining further axially inward displacement of the bead 7.

Thus in summary, in conditions which cause the bead to be displaced from its normal seating position and thus out of the first recess 15, the bead will be engaged into the second recess 20 until the lateral force to which the tyre is subjected is relieved and the tyre bead returns to its normal position.

In a modification of the tyre and rim assembly of the embodiment described above recess 15 has convexly curved walls and is deeper than the second axially spaced recess 20.

The axially inner recess may be provided with an assymmetric cross-section to improve its bead hold. The axially inner surface of the recess can be made steeply sloping so that the bead toe extension of the tyre, which is in a tilted condition as it slides over the central portion of the rim, strikes a substantial barrier area and is thus prevented from further movement. Furthermore, to assist recovery of the bead from the inner recess back to the first recess the axially outer surface of the inner recess may have a small slope.

The recesses are preferably shaped so that they can be formed by a rolling operation which is the standard wheel rim production technique, and the profiles may be varied through a range of shapes which can be rolled into the rim. The recesses are profiled so that they can accommodate the bead toe extension of the adjacent bead to restrain the bead against axial movement in the manner described above and in out U.S. Patent Specification No. 1 395 714.

WHAT WE CLAIM IS: 1. A tyre and wheel rim assembly comprising a pneumatic tyre mounted on a wheel rim furnished with peripheral tyre bead retaining flanges, inboard and outboard tyre bead seating portions and a well between said bead seating portions, a first annular radially inwardly extending recess being formed adjacent the axially inner edge of the outboard bead seating portion to accommodate a radially inwardly extending annular extension of the toe portion of the associated tyre bead when the tyre is normally seated on the rim the extension resting freely in said first recess and the extended toe and recess each being of cross-sectional shape and size which permits said toe to be compressed into said first recess upon tilting of the bead under the influence of lateral forces on the tyre whereby said bead is restrained from movement axially across the rim, and a second annular radially inwardly extending recess formed in the rim, the rim having a substantially flat ledge (as viewed in axial crosssection) disposed between said first and second annular recesses, and said first and second annular recesses, and said first and second annular recesses being disposed between the outboard bead seating portion and the well.

2. A wheel rim for a pneumatic tyre and wheel rim assembly as in claim 1 comprising peripheral tyre bead retaining flanges, inboard and outboard tyre bead seating portions and a well positioned between said seating portions, the rim having first and second radially inwardly extending recesses said first recess being disposed adjacent the axially inner edge of the outboard bead seating portion, and the rim having a substantially flat ledge (as viewed in axial cross-section) disposed between said first and second annular recesses, said first and second annular recesses being disposed between the outboard bead seating portion and the well.

3. A wheel rim according to Claim 2, wherein instead of said second annular recess the rim has two or more such annular recesses disposed between the outboard bead seating portion and the well.

4. A wheel rim according to Claim 2 or 3 wherein said second annular recess or, where there are two or more such recesses, the axially innermost one is positioned adjacent the axially innermost one is positioned adjacent the axially inner edge of the ledge and merges into a wall of the well.

5. A wheel rim according to Claim 4 wherein the axially inner edge of said second annular recess (or the innermost of two or more such recesses) and the axially outer wall of the well together form a hump which extends radially outwardly of the ledge.

6. A wheel rim according to any one of claims 2 to 5, wherein the cross-sectional profile of each of the recesses is "U"-shaped.

7. A wheel rim according to any one of claims 2 to 5, wherein the cross-sectional profile of each of the recesses is "V"-shaped.

8. A wheel rim according to any one of claims 2 to 7 wherein said second annular recess or said two or more annular recesses has an asymmetric cross-section and the axially inner surface of said recess has a steeper slope than the axially outer surface.

9. A wheel rim according to any one of claims 2 to 8 wherein the recesses have been formed by a rolling process.

10. A wheel rim according to any one of claims 2 to 9 wherein the inboard tyre bead seating portion is provided with a radially outwardly extending abutment which serves to restrain axial inward displacement of the inboard tyre bead when used in service.

11. A tyre and wheel rim assembly constructed and arranged substantially as described herein with reference to the accompanying drawing.

12. A wheel rim constructed and arranged substantially as described herein with reference to the accompanying drawing.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. slope. The recesses are preferably shaped so that they can be formed by a rolling operation which is the standard wheel rim production technique, and the profiles may be varied through a range of shapes which can be rolled into the rim. The recesses are profiled so that they can accommodate the bead toe extension of the adjacent bead to restrain the bead against axial movement in the manner described above and in out U.S. Patent Specification No. 1 395 714. WHAT WE CLAIM IS:

1. A tyre and wheel rim assembly comprising a pneumatic tyre mounted on a wheel rim furnished with peripheral tyre bead retaining flanges, inboard and outboard tyre bead seating portions and a well between said bead seating portions, a first annular radially inwardly extending recess being formed adjacent the axially inner edge of the outboard bead seating portion to accommodate a radially inwardly extending annular extension of the toe portion of the associated tyre bead when the tyre is normally seated on the rim the extension resting freely in said first recess and the extended toe and recess each being of cross-sectional shape and size which permits said toe to be compressed into said first recess upon tilting of the bead under the influence of lateral forces on the tyre whereby said bead is restrained from movement axially across the rim, and a second annular radially inwardly extending recess formed in the rim, the rim having a substantially flat ledge (as viewed in axial crosssection) disposed between said first and second annular recesses, and said first and second annular recesses, and said first and second annular recesses being disposed between the outboard bead seating portion and the well.