GB2127361A

GB2127361A - Pneumatic vehicle tyre

Info

Publication number: GB2127361A
Application number: GB08322813A
Authority: GB
Inventors: Klaus Thielemann; Willi Bachmann
Original assignee: Continental Gummi Werke AG
Current assignee: Continental AG
Priority date: 1982-09-21
Filing date: 1983-08-25
Publication date: 1984-04-11
Also published as: GB8322813D0; FR2533170A1; GB2127361B; FR2533170B1; ZA836416B; DE3234889A1; IT8322737A0; JPS5977908A; IT1168714B

Abstract

The tyre (for goods vehicles) has a single layer radial carcase (1) of steel cords of which the end (4) is wrapped around the bead core (3) and is protected by a cross-laid multi-layer textile reinforcement (7). At least the axially outermost layer (10) of the bead reinforcement (7) is completely wrapped around the bead core (3) and ends in a region bounded by the bead core (3) and the end of the radially outermost first ending layer (8) of the bead reinforcement (7). The reinforcement (7) may consist of three (as shown) or four layers, one (as shown) or two of which are wrapped around the bead core. The cords of the layers may be rayon, polyester or polyamide and extend at 15 DEG -50 DEG w.r.t. the circumferential. <IMAGE>

Description

SPECIFICATION Pneumatic vehicle tyre The present invention relates to a pneumatic vehicle tyre for goods vehicles having preferably a single radial carcase of steel cords or a material of similarly high strength, in which the carcase is anchored to the bead by being wrapped around the bead core, and in which the wrapped around ends of the carcase extend to a height equivalent to 0.1 to 0.3 times the cross-sectional height of the tyre, and in which furthermore a bead reinforcement overlapping the ends of the carcase comprises several adjacent cross-laid layers of inextensible textile reinforcing members which are arranged in cords and form an angle of from 1 5, to 50 with the circumferential direction of the tyre, wherein at least one layer ends radially inwardly in the vicinity of the side of the bead core and the region of the overlapping part of the carcase lying radially outwardly extends to the overlapping carcase end in the next layer at a distance therefrom.

In tyres of the type specified it is known that bead reinforcements are used to prevent, or at least to substantially reduce, detachment phenomena in the vicinity of the overlapping ends of the carcase as a result of the high stressing in this region when in use. In known tyres this is achieved by providing a bead reinforcement which runs radially outwards over the overlapping ends of the carcase into the region of the side wall of the tyre in order to reduce the load on the region mentioned.

In a known tyre, the bead reinforcement consists of at least two adjacent cross-laid layers which are arranged radially outwards in a staggered fashion with respect to each other and the overlapping carcase ends extend radially inwards at least as far as the side region, preferably as far as the region beneath the bead core. This known bead reinforcement has proved itself in many practical applications.

However it has been found in the case of certain vehicle wheels with cord shouldered tyres and small wheel rim heights that thrust forces occur in the region alongside the bead core which are due primarily to the pressure from the rim and give rise to the danger of detachment for the layers of bead reinforcement ending in this region.

It is an object of the invention to improve the bead reinforcement in such a way that detachment in this endangered area is reliably avoided.

According to the present invention there is provided a pneumatic vehicle tyre for goods vehicles preferably having a single layer carcase of steel cords or a material of similarly high strength, in which the carcase is anchored by being wrapped around the bead core in the bead, and in which the wrapped around ends of the carcase extend to a height equivalent to 0.1 to 0.3 times the crosssectional height of the tyre, and in which a bead reinforcement overlapping the ends of the carcase comprises several layers of inextensible textile reinforcing members which are arranged in cords and form an angle of from 15 to 50 with the circumferential direction of the tyre, wherein at least one layer ends radially inwardly in the region of the side of the bead core and the layer lying next to the wrapped around carcase end extends to the radially outer region of the wrapped around end of the carcase towards and at a distance therefrom, characterised in that at least the axially outermost layer of the bead reinforcement is completely wrapped around the bead core and ends axially inwardly in a region which is bounded by the bead core and the end of the radially outermost first ending layer of the bead reinforcement.

As the axially outermost layer of the bead reinforcement is completely wrapped around the bead core to the specified height, additional reinforcement of the tyre in the region above the bead core axially inwards of the overlapping carcase ends is achieved in addition to reliable covering of the inner layers so that the bending line of the tyre is displaced inwards and the particularly endangered region at the overlapping carcase ends is re lived.

Additionally, more accurate positioning of the underlying layers is achieved through the supportive effect of the covering layer.

The present invention will be further illustrated, by way of example, with reference to the accompanying drawings which relate to a bead reinforcement in which the layers end and are feathered off radially outwards. Whilst the invention has provided particularly good results with a bead reinforcement of this type, it can obviously also be applied to bead reinforcements which are formed in another radially outward fashion.

As illustrated: Figure 1 shows a partial radial cross-section through a pneumatic vehicle tyre in the form of a belted tyre; Figure 2 shows the bead part of the tyre according to Fig. 1 in a magnified form with three layers of bead reinforcement and one layer wrapped around the bead core; Figure 3 shows the bead'part with three layers of core reinforcement and two layers wrapped around the bead core; and Figure 4 shows the bead part with four layers of reinforcement and one layer wrapped around the bead core.

The pneumatic vehicle tyre which is predominantly made of rubber or a rubber-like substance comprises a radial carcase 1 having steel cords as reinforcing members running at right angles to the circumferential direction of the tyre. These steel cords are anchored in the tyre bead 2 by being wrapped around the inextensible steel bead core 3. The end 5 of laterally outwardly overlapping part 4 of carcase 1 extends to a height equivalent to 0.1 to 0.3 times the cross-sectional height of the tyre.

An inextensible belt 6, which is located between the carcase 1 and the running strip which incorporates the tread and which extends substantially over the width of the running strip on the outer periphery of the tyre, acts as a crown-reinforcement for the tyre as well as laterally stabilising the carcase 1.

A bead reinforcement 7 is located externally and to the side of overlapping portion 4 of the carcase 1, and consists of several adjacent layers 8, 9, 10 (Fig. 2), 8', 9, 10 (Fig. 3) and 8, 9, 10', 11 (Fig. 4) of rubber coated inextensible textile reinforcing members which are arranged into cords and form angles of preferably 30 and 1 50, with the circumferential direction of the tyre (calculated anticlockwise) so that a cross-ply is achieved. The number of layers depends on the application or size of the tyre so that only two layers may be sufficient for light goods vehicles whilst three layers are to be preferred for medium goods vehicles and four layers for heavy goods vehicles. Rayon, polyester or polyamide may be used as a material for the textile reinforcing members.

The outer ends of individual layers 8 or 8', 9, 10 or 10' and 11 are arranged together and with the wrapped around portion 4 of the carcase 1 in a staggered arrangement so that there is a decided feathering off. By this means both the region at the end of wrapped around portion 4 of the carcase 1 is reinforced and held firm and the forces taken up by the bead area when travelling are distributed in stages over the individual layers so that the total force is only taken up piecemeal by specific points lying in the region of the side wall as far as one half the height of the tyre cross-section.

Feathering of layers 8 or 8', 9, 10 or 10' and 11 of bead reinforcement 7 has proved particularly advantageous, the radial distance between the carcase end 5 and the first ending layer 8 or 8' being 0.25 to 0.4 times the height defined by carcase end 5, while the radial distance between the ends of the layers amounts to some 0.15 to 0.35 times this height.

In the case of the bead reinforcement 7 according to Fig. 2, textile layers 8, 9 lying next to the wrapped around carcase end 5, end internally and radially somewhat to the side of bead core 3 while the axially outermost layer 10 is wrapped right around bead core 3 and ends at a level which approximately corresponds to the height of the wrapped around carcase end 5. With this arrangement of layer 10, the ends of layers 8 and 9 are completely covered in the direction of the wheel rim so that forces occurring in the heel region of the tyre are not transmitted to the inner layers of the bead region of the tyre and the radially innermost ends of layers 8 and 9 are protected from detachment.

As a result of the relatively broad vertical extent of covering layer 10 axially inside of carcase 1 this region is reinforced so that the bending line of the tyre is displaced towards the interior and sheds the load in the region of the wrapped around carcase end 5.

The bead part of the tyre according to Fig.

3 differs from that in Fig. 2 in that inner layer 8' is also completely wrapped around bead core 3. This produces additional reinforcement of the inner bead region.

The embodiment according to Fig. 4 features a four layer bead reinforcement 7 in which the laterally outermost layer 11 is alone in being completely wrapped around bead core 3 while the three other layers 8, 9, 10' end radially inwards within the region beside bead core 3 and are covered by layer 11.

In order to couple the properties of the wrapped around portion 4 of carcase 1 with the high stiffness of the steel cords in the hazardous region of the carcase end 5 with the properties of the more yielding layers of textile 8 or 8', 9, 10 or 10' and 11, an intermediate space of filling rubber 1 2 is provided between inner layer 8 or 8' of the bead core reinforcement 7 and the wrapped around portion 4 of carcase 1 over bead core 3, which space has a width immediately beside carcase end 5 which is equivalent to 0.2 to 0.4 times the distance between carcase end 5 and the remainder of the carcase 1 and decreases radially inwards in the less mobile bead region. Optimum results have been achieved with a width equivalent to 0.3 times the stated distance.

Claims

1. A pneumatic vehicle tyre for goods vehicles preferably having a single layer carcase of steel cords or a material of similarly high strength, in which the carcase is anchored by being wrapped around the bead core in the bead, and in which the wrapped around ends of the carcase extend to a height equivalent to 0.1 to 0.3 times the crosssectional height of the tyre, and in which a bead reinforcement overlapping the ends of the carcase comprises several layers of inextensible textile reinforcing members which are arranged in cords and form an angle of from 15 to 50D with the circumferential direction of the tyre, wherein at least one layer ends radially inwardly in the region of the side of the bead core and the layer lying next to the wrapped around carcase end extends to the radially outer region of the wrapped around end of the carcase towards and at a distance therefrom, characterised in that at least the axially outermost layer of the bead reinforcement is completely wrapped around the bead core and ends axially inwardly in a region which is bounded by the bead core and the end of the radially outermost first ending layer of the bead reinforcement.

2. A pneumatic vehicle tyre as claimed in claim 1, in which the bead reinforcement consists of three layers of fabric, and in which one layer is completely wrapped around the bead core.

3. A pneumatic vehicle tyre as claimed in claim 1, in which the bead reinforcement consists of three layers of fabric, and in which two layers are completely wrapped around the bead core.

4. A pneumatic vehicle tyre as claimed in claim 1, in which the bead reinforcement consists of four layers of fabric, and in which one layer is completely wrapped around the bead core.

5. A pneumatic vehicle tyre, substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.