CA2776559C

CA2776559C - Pneumatic vehicle tire

Info

Publication number: CA2776559C
Application number: CA2776559A
Authority: CA
Inventors: Franz Diensthuber
Original assignee: Continental Reifen Deutschland GmbH
Current assignee: Continental Reifen Deutschland GmbH
Priority date: 2009-11-23
Filing date: 2010-09-30
Publication date: 2017-08-29
Anticipated expiration: 2030-09-30
Also published as: CA2776559A1; DE102009044620A1; NO2504180T3; EP2504180B1; WO2011060990A1; EP2504180A1

Abstract

The invention relates to a vehicle pneumatic tire, in particular for use in winter driving conditions, having a tread which is segmented into tread lugs (2, 5, 6) by scores (4), grooves (3, 14) and the like, wherein there are tread lugs (6), each having at least three indents (12) extending substantially in a corresponding direction and each running under an angle of 45° at a maximum to the transverse direction of the tread. According to the invention, the tread has tread lugs (6), the indents (12) thereof having angles of varying size (a1 to a6) to the transverse direction of the tread, which are incrementally larger or smaller from indent (12) to indent (12), beginning at one of the two outermost indents (12) in the circumferential direction of the tread lug (6).

Description

Description Pneumatic vehicle tire The invention relates to a pneumatic vehicle tire, in particular for use in winter driving conditions, with a tread rubber, which is divided by channels, grooves and the like into tread bars, wherein tread bars that are respectively provided with at least three sipes are provided, said sipes extending in the same direction and each running at an angle of at most 45 in relation to the transverse direction of the tread rubber.
It is known and customary to provide pneumatic vehicle tires that are intended for use in winter driving conditions with tread bars in the tread rubber which each have a number of sipes with a width of between 0.4 mm and 0.6 mm. These sipes may be configured in various ways; for example, it is customary to provide sipes which in plan view run in a wavy or zigzagging form or sipes with portions of a zigzagging or wavy form.
Portions running in a zigzagging or wavy form may, for example, be combined with portions which in plan view run in a straight line, which are usually those that end in grooves. It is also known that sipes influence the transverse stiffness and circumferential stiffness of the tread bar, the angle of inclination of the sipes in relation to the transverse direction of the tire and the configuration of the sipes being significant among the influencing factors in this respect.
In some countries it is permitted to provide the tread rubber of winter tires with spikes, although legal regulations require that the middle third of the contact area of the tread rubber must remain free from spikes. As a result of their reduced sliding and slipping movements, the spiked tread bars are subject to less wear during the operation of the tire, and

- 2 -therefore the spike-free middle portion of the tread rubber wears more in comparison with them. It is known that the increased wear in the middle region of the tread rubber can be compensated by increasing the positive component in this region, for example by providing narrower grooves. If, therefore, as a result of the narrow grooves, tread bars in the central region of the tread rubber are comparatively long in the circumferential direction, their circumferential stiffness increases correspondingly. The greater stiffness of these tread bars in the circumferential direction is, however, contrary to the originally desired effect of reducing the tread wear in the middle region by providing a greater positive component.
The invention is based on the object of being able in the case of a tire of the type mentioned at the beginning to reduce or increase, and thereby deliberately influence, the circumferential stiffness of tread bars with sipes by means of a simple measure.
The stated object is achieved according to the invention by the tread rubber having tread bars of which the sipes form angles of different sizes with the transverse direction of the tread rubber, said angles being progressively greater or smaller from sipe to sipe, beginning with one of the two outermost sipes in the circumferential direction of the tread bar.
By this simple measure, the circumferential stiffness of a tread bar can be deliberately influenced. The extent of the change of the angling of the sipes and the actual size of the angles determine the direction of the effect on the circumferential stiffness.
Particularly advantageous are changes of angle of the order of 10 to 1.5 . Even with a greater number of sipes, the other properties of the tread profile that '

- 3 -are essential for a winter tire, such as traction and breaking behavior on ice and snow, are optimally retained as a result.
In this connection it is also favorable if the greatest angle is at most 300, in particular at most 25 .
In the case of tread bars that are longer in the circumferential direction, the number of sipes that form angles of different sizes with the transverse direction of the tread rubber may easily be up to seven for each tread bar, since even small changes of angle bring about the desired effect.
The invention is of particular advantage in the case of a pneumatic vehicle tire of which the tread rubber is provided with spikes, the middle third of the area of the tread rubber that comes into contact with the ground being free from spikes and including that circumferential region in which the positive component is greatest and tread bars of great circumferential extent run. In this case, influencing of the circumferential stiffness of the tread bars in the middle region of the tread rubber is advantageous for uniform wear.
Therefore, the tread rubber is designed in such a way that the tread bars have in this circumferential region sipes which, as - 25 provided by the invention, form angles of different sizes with the transverse direction of the tread rubber. The measure according to the invention allows the circumferential stiffness of the longer bars to be reduced, and in this way the wear to be made more uniform.
In one aspect, the invention provides a pneumatic vehicle tire, comprising a tread rubber divided into tread bars, each one of ak 02776559 2017-01-27 - 3a -the tread bars having a circumference delimited by grooves provided in the tread rubber, wherein at least some of the tread bars are tread bars provided with at least three sipes, each one of the at least three sipes forming an angle of at most 45 in relation to a transverse direction of the tread rubber, said angle being progressively greater or smaller, by 1 to 1.5 , from one of the at least three sipes to an adjacent one of the at least three sipes, beginning with one of the two outermost sipes in a circumferential direction of the tread bars provided with the at least three sipes.
Further features, advantages and details of the invention are now described in more detail on the basis of the drawing, which schematically represents an exemplary embodiment and in which:

- 4 -Figure 1 shows a plan view of a portion of a tread profile of a pneumatic vehicle tire with an embodiment of the invention.
In Figure 1, A-A denotes the tire equator, by which the tread rubber of the pneumatic vehicle tire is divided into two halves. The configurational variant of a tread rubber that is represented is intended for pneumatic vehicle tires for passenger cars, and in particular for use in winter driving conditions.
The figure shows a circumferential portion of the tread rubber with one of the two halves of the tread. In the second half of the tread there may be identical, similar or differently designed profile structures, for example the tread rubber may have what is known as an asymmetrical profile or a profile with a directional tread pattern. The profile structures shown in Figure 1 include a row of bars 1 at the shoulder, the tread bars 2 of which are separated from one another by transverse grooves 3, which run substantially in the transverse direction of the tread rubber. The transverse grooves 3 continue in the direction of the middle of the tread rubber as oblique channels 4, which run at an angle p of 30 to 45 with respect to the circumferential direction or the tire equator A-A. Two tread bars 5, 6 are respectively arranged between circumferentially adjacent oblique channels 4. The tread bars 5 located approximately in the middle region of the half of the tread that is shown are configured in plan view substantially in the form of a parallelogram, each with two acute-angled corners and two obtuse-angled corners.
The tread bars 5 are separated from the adjacent tread bars 2 and the adjacent tread bars 6 by further channels 7, 8, which run in the opposite sense to the oblique channels 4 at angles 71, 72, of approximately 30 to 50 , in relation to the circumferential direction of the tire (tire equator A-A). The tread

- 5 -bars 6 provided in the central region of the tread rubber are adjoined in the second half of the tread by a circumferential groove 14 running in a zigzagging form, each tread bar 6 being delimited by two portions of the zigzag of the groove 14 and having in plan view the shape of an irregular pentagon. This form of the tread bars 6 is merely given by way of example;
depending on the configuration of the circumferential groove, the tread bars may also have a different form, for example a trapezoidal form. The tread bars 6 following one another in the circumferential direction are respectively separated from one another by a portion 4a of the oblique channel 4 that is made much narrower than the other regions or portions of the oblique channel.
All of the tread bars 2, 5, 6 of the tread rubber shown in Figure 1 each have a number of sipes 10, 11 and 12, the width of which is between 0.4 mm and 0.6 mm. The sipes 10 arranged in the tread bars 2 at the shoulder run parallel to one another and to the edges of the tread bars 2 delimiting the transverse grooves 3 and have in plan view a combination of straight and wavy running portions. The wavy running portions are for the most part located in the middle region of the sipes 10.
The number of sipes 10 for each tread bar 2 is chosen between two and five, depending on the size of the circumferential extent of the tread bars 2. Their distance from one another and their distance from the edges of the bars delimiting the transverse grooves 3 are essentially the same. The sipes 11 in the tread bars 5 are likewise arranged parallel to one another and have for the most part a middle portion which in plan view runs in a wavy form and two straight-running outer portions, which end in the oblique channels 4. In the case of the embodiment shown, furthermore, the orientation or extent of the sipes 11 is adapted to the ' CA 02776559 2012-04-03

- 6 -extent of the channels 7 and 8; the sipes 11 run substantially parallel to the channels 7 and 8.
The sipes 12 formed in the tread bars 6 are likewise made up of a middle portion which in plan view is of a wavy form and two straight-running lateral portions.
Depending on how great the circumferential extent of the tread bars 6 is, the number of sipes 12 for each tread bar 6 is at least three; in the case of the embodiment shown, six sipes 12 for each tread bar 6 are provided. In the case of differently designed tread bars, the number of sipes 12 may also be greater than six. The sipes 12 are sipes oriented in the transverse direction of the tread rubber, that is to say they form an angle which is less than 450, in particular less than 30 , with the transverse direction of the tread rubber. In the case of the configurational variant shown, the path followed by the sipes 12 is based on the path or the inclination of the channels 8. Through each sipe 12 there can be placed a straight line gi to g6, running in the direction of the extent thereof.
Within each tread bar 6, the angle al to a6 that the straight lines gi to g6 form with the transverse direction of the tire becomes progressively either greater or smaller from sipe 12 to sipe 12 for all the sipes 12, beginning with one of the first sipes 12 in the circumferential direction. The change of angle is between 1 and 1.5 . Thus, for example, in the case of the configurational variant shown, the angle al of the straight line gi of the sipe 12 of each tread bar 6 that is running alongside the channel 8, measured in relation to the transverse direction, is approximately 25 , the angle a6 of the straight line g6 through the last sipe 12 in the circumferential direction is 12 .
Depending on the configuration of the profile structures or the tread bars, the sipes 12 may also be arranged in such a way that their orientation in the

- 7 -tread bars 6 deviates from each of the adjacent channels or grooves.
The tread rubber shown is provided with a multiplicity of spikes 9, which are merely indicated in the figure, spikes 9 being positioned by way of example in some shoulder bars 2 and tread bars 5. The arrangement of the spikes 9 in the tread rubber is such that at least the middle third of the contact area of the tread rubber remains free from spikes. This measure conforms to the legal requirements in some European countries and was provided for the reason of reducing the wear of the road surfacing by the use of spiked tires. In the spiked regions of the tread rubber, the sliding and slipping movements of the tread bars are reduced when the tire is in contact with the ground during rolling, whereas the spike-free middle or central region of the tread rubber undergoes greater wear. In the middle or central region of the tread rubber, therefore, the profile structures are designed in such a way that they have a greater positive component than the profile structures in the lateral regions of the tread rubber.
As known, the positive component is the proportion in percent of the total area of a specific tread rubber region that is made up by the area coming into contact with the ground. In the case of a high positive component, therefore, the area taken up by the grooves, channels and the like is comparatively small. In the case of the present tread rubber, the positive component is great, in particular as a result of the narrow portions 4a, while at the same time the circumferential length of the tread bars 6 is relatively great. The tread bars 6 consequently have a greater circumferential stiffness than the circumferentially shorter tread bars 5. The greater circumferential stiffness of the tread bars 6 counteracts the effect intended by the greater positive component - that of reducing wear. The particular = CA 02776559 2012-04-03

- 8 -arrangement of the sipes 12 running in the tread bars 6 reduces the circumferential stiffness of the tread bars 6, and therefore the advantage of increased wear resistance as a result of a greater positive component can be retained.
The invention is not restricted to the exemplary embodiment represented. All of the sipes, even those that change their angling in the way provided by the invention, may run in a slightly arcuate form in plan view. The sipes may, furthermore, run in a linear, zigzagging or wavy form over their entire length. The number of sipes may vary; it is even possible for tread bars with one or two sipes to be provided.

,

- 9 -List of designations 1 ....................... row of bars 2 ....................... tread bar 3 ....................... transverse groove 4 ....................... oblique channel ...... _ ....... __tread bar 6 ....................... tread bar 7 ....................... channel 8 ....................... channel 9 ....................... spike ...................... sipe 11 ...................... sipe 12_____ ................ sipe 14 ...................... circumferential groove 13 ...................... angle Yi ...................... angle Y2 ...................... angle al to a6_angles

Claims

WHAT IS CLAIMED IS:

1. A pneumatic vehicle tire, comprising a tread rubber divided into tread bars, each one of the tread bars having a circumference delimited by grooves provided in the tread rubber, wherein at least some of the tread bars are tread bars provided with at least three sipes, each one of the at least three sipes forming an angle of at most 45° in relation to a transverse direction of the tread rubber, said angle being progressively greater or smaller, by 1° to 1.5°, from one of the at least three sipes to an adjacent one of the at least three sipes, beginning with one of the two outermost sipes in a circumferential direction of the tread bars provided with the at least three sipes.

2. The pneumatic vehicle tire of claim 1, for use in winter driving conditions.

3. The pneumatic vehicle tire of claim 1 or 2, wherein the angle is of at most 30°.

4. The pneumatic vehicle tire of claim 1 or 2, wherein the angle is of at most 25°.

5. The pneumatic vehicle tire of any one of claims 1 to 3, wherein each of the tread bars provided with the at least three sipes are tread bars provided with up to seven sipes.

6. The pneumatic vehicle tire of any one of claims 1 to 5, wherein the tread rubber is provided with spikes, the middle third of the area of the tread rubber that comes into contact with the ground being free from spikes, wherein the tread bars provided with the at least three sipes are arranged in the middle third of the area of the tread rubber that comes into contact with the ground.

7. The pneumatic vehicle tire of any one of claims 1 to 6, wherein the tread bars provided with the at least three sipes are arranged along the tire equator.