Pneumatic vehicle tire

The invention is directed to a pneumatic vehicle tire with a foam sound absorber therewithin and adhesively attached to the inner side opposite from the tread. The sound absorber has a contact side, by which it adheres to a previously applied, self-sealing sealant. The sealant has a tackiness required for the adhesive attachment of the sound absorber. The contact side of the sound absorber has a contact area on the sealant of between 5% and 50% with respect to the total area of the contact side.

FIELD OF THE INVENTION

The invention relates to a pneumatic vehicle tire with a foam sound absorber inside it, adhesively attached to the inner surface opposite from the tread, the sound absorber having a contact side, by which it adheres to a previously applied, self-sealing sealant, and the sealant having at least immediately after its application a tackiness required for the adhesive attachment of the sound absorber.

BACKGROUND OF THE INVENTION

Such a pneumatic vehicle tire is known from DE 10 2007 028 932 A1. The sound absorber, also known as an inner absorber, is a ring composed of open-cell foam which reduces the vibration of air in the tire and leads to an improvement in the noise conditions in the vehicle. The high-viscosity sealant applied to the inner side of the tire has two functions. First, the sealant seals an undesired puncture of the tire in the region of the tread, in that in the event of damage to the inner layer, the viscous sealant flows into the location of the damage. Second, the sealant serves at the same time as a “bonding agent” for securing the sound-absorbing foam ring.

However, the flow characteristics of the high-viscosity sealant may be adversely affected by the inner absorber lying on the sealant over its full surface area, meaning that the desired sealing effect only occurs after a delay or not at all. In cases in which the penetrating foreign body comes out of the tire again and leaves a large air channel, reliable sealing by the sealant adversely affected in terms of its flow characteristics is particularly difficult, especially at low temperatures.

SUMMARY OF THE INVENTION

It is an object of the invention to improve the sealing of the tire in the event of punctures, along with at least equally good sound absorption.

The above object is achieved according to the invention by the contact side of the sound absorber having a contact area on the sealant that takes up between 5% and 50% with respect to the total area of the contact side.

According to the invention, the sound absorber is formed and arranged inside the tire in the form of a circular ring. The fact that the sound absorber is not adhesively attached to the sealant over the full surface area but only the contact area, which takes up a much smaller area than the total area of the contact side, means that a considerable free surface area of the sealant is created. As a result, the flow characteristics of the sealant in cases of puncture, and consequently the sealing of the tire, are improved. The probability of a perforation/puncture lying within the contact area of the sound absorber is also reduced, thereby likewise improving sealing.

In spite of the reduced contact area, it is still large enough to provide great resistance to the centrifugal forces occurring when driving at high speed.

In this case, the sound absorber may be a closed or open ring. “Open” means here that the ring is not closed in the form of a circular ring, but has two ends between which a gap is formed.

“Contact side” means that side of the sound absorber that is facing the sealant.

“Contact area” means that area of the contact side that comes directly into (adhesively bonding) contact with the sealant.

“Total area of the contact side” means that area that would be covered if a planar body with outer edges of the same length were to lie on the sealant.

The sealant layer is arranged in the form of a circular ring on the inner side of the tire, under the tread, and has at least such a width that corresponds approximately to the width of the belt plies of the tire.

To improve the sealing further, the contact side of the sound absorber has a contact area on the sealant of between 10% and 40%, preferably between 10% and 30%, with respect to the total area of the contact side. The smaller the contact area is, the better the sealing in cases of puncture. However, the contact area must still be large enough that the sound absorber can be securely fastened on the sealant.

In a preferred configuration of the invention, the sound absorber is a convoluted foam, the contact side of the sound absorber having the convolutions or nubs, the tips of the convolutions lying on the sealant and the convoluted foam preferably having a thickness of 10 mm to 50 mm, with preference of 20 mm to 30 mm. In addition to the improved sealing, here the sound absorption is likewise improved by an increase in the surface area of the sound absorber. Furthermore, the covering of the tacky sealant surface means that soiling effects, such as for example soiling of the rim when the tire is being pulled onto the rim, are reduced.

In another preferred configuration of the invention, the sound absorber is a half tube, the cross section of which is a half circle or a half oval, the walls of the half tube lying on the sealant. Instead of a half tube, two or more half tubes may also be arranged parallel in terms of their longitudinal axis. In addition to the improved sealing, here the sound absorption is likewise improved by an increase in the surface area of the sound absorber. Furthermore, soiling effects, such as for example soiling of the rim when the tire is being pulled onto the rim, are reduced by the covering of the tacky sealant surface.

It is expedient if the sealant is a viscous mixture on the basis of a butyl rubber, a polybutene or on the basis of silicone.

Since the flowability of the sealant is improved by the small contact area of the sound absorber, the layer thickness of the sealant can be reduced and be between 2 mm and 5 mm, preferably approximately 3.5 mm. This saves costs and also tire weight.

In order not to soil the rim with sealant when fitting the tire, it is advantageous if the sound absorber is arranged eccentrically with respect to the zenith of the tire. The sound absorber is preferably arranged displaced in the direction of the outer side of the tire.

As an alternative to the eccentric arrangement of the sound absorber, it may have such a width that corresponds approximately to the width of the sealant. Here, too, the rim is not soiled during fitting of the tire as a result of the sealant being covered by the sound absorber.

DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION

FIG. 1depicts a cross section through a radial automobile tire having a profiled tread1, sidewalls2, bead regions3, bead cores4and also a multi-ply belt assembly5and a carcass insert6. On its inner surface, the tire is covered with an inner layer7of an airtight rubber compound. Applied to the inner surface of the inner layer7, the inner surface being opposite from the tread1, is a sealant8which in the event of puncture—tire damage—is capable of behaving in a self-sealing manner. An inner absorber9in the form of a circular ring adheres to the sealant8over the full surface area, with the function of a sound absorber, as described below. The sound absorber9has a contact side13. The contact side13is that area of the sound absorber that is facing the sealant8. Because contact is over the full surface area, here the contact side13corresponds to the contact area14. With respect to its sound-absorbing properties, the inner absorber9is matched to the tire cavity frequency. The inner absorber9has here, for example, an approximately elongated triangular cross section that is symmetrical with respect to the axis of symmetry of the tire—which passes through the zenith of the tire—and adheres on the sealant8by its contact side13over the full surface area. The foam of the inner absorber9is an open-cell foam, since this is best suited to absorbing sound. Possible sealants are, for example, polyurethane gels or viscous mixtures based on butyl rubbers, polybutenes or silicone, it being possible for the mixtures to contain the customary further constituents, such as plasticizer oils. The sealant is introduced, for example by spraying, such that it covers at least the inner surface opposite from the tread1. The tire can be rotated in order to optimally distribute the sealant on the inner surface. Furthermore, the sealant is introduced in such an amount that the layer thickness of the sealant is between 7 mm and 8 mm. The prefabricated inner absorber9is introduced into the interior of the tire. After full reaction, the inner absorber9adheres to the sealant8, which is elastically deformable, but remains immobile to a very great extent.

FIG. 2shows a perspective view of a portion of a sound absorber9of open-cell foam that can be used in a pneumatic vehicle tire according to the invention for automobiles, for example of the size 235/40 R 18.

The sound absorber9is comprised of a convoluted foam, the contact side13of the sound absorber9having the convolutions or nubs11. The sound absorber9lies with the tips of the convolutions11in an adhering manner on the sealant (not depicted). The surface area opposite from the contact side13may in this case be planar and smooth or likewise have a structure for improved sound absorption. Only the tips of the convolutions11lie on the sealant, so that the contact area on the sealant comprises between 5% and 50% with respect to the total area of the contact side13. All of the convolutions11have approximately the same height12. The convoluted foam has a thickness18of approximately 30 mm, measured at the thickest point of the convoluted foam.

FIG. 3shows a perspective view of a portion of a further sound absorber9that can be used in a pneumatic vehicle tire according to the invention. The sound absorber9consists of a half tube or two half tubes placed next to one another (not depicted), the cross sections of which are half circles. The walls15of the half tube/half tubes lie on the sealant (not depicted). The sound absorber9is arranged in the tire in such a way that the longitudinal axis of the half tube/half tubes (dashed line) is arranged parallel to the circumferential direction of the tire. For the tire size 235/40 R 18, the sound absorber9has a width16of 120 mm, the width being measured from outer surface to outer surface, parallel to the axial direction aR and at the widest point.

The sound absorber9has a height17of 60 mm in the case of a single half tube and 30 mm in the case of two half tubes lying next to one another, the height being measured parallel to the radial direction rR and at the highest point.

LIST OF REFERENCE SIGNS