Note: Descriptions are shown in the official language in which they were submitted.
202006001
PCT/DE2021/200254
Pneumatic vehicle tyre with central circumferential rib
Description
[0001]The invention relates to a pneumatic vehicle tire having a tread which
has a
profile. The profile of the tread has two circumferential channels that
encircle the
entire tire. A middle circumferential rib of the profile is delimited by two
sides, running
parallel to one another, of these two circumferential channels, which sides
run
perpendicular to the axial direction A of the pneumatic vehicle tire. Said
circumferential rib has, at regular spacing intervals in a circumferential
direction,
sipes which run from one to the other of the mutually parallel sides of the
two
circumferential channels along a contour line.
Prior art
(0002] Pneumatic vehicle tires that are also suitable for use in winter,
normally
referred to for short as winter tires, must keep a vehicle stable on a roadway
even
when said roadway is covered in snow or ice. This winter performance, which
encompasses snow and ice performance, also includes safe cornering with the
vehicle, and safe launching and braking with the vehicle.
(0003] To achieve these characteristics, the tread of the pneumatic vehicle
tire has
a correspondingly designed profile.
[0004]The snow performance of the tire is contributed to primarily by three
mechanisms of action: rubber-on-snow friction, snow-on-snow friction, and the
edge
(shear) action of the profile structure.
(0005] The rubber-on-snow friction of a pneumatic vehicle tire is determined
here by
the rubber material of the tread, in particular by the rubber material on the
surface
of the tread.
[0006]To increase the snow-on-snow friction, the profile of the tread of the
pneumatic vehicle tire has structures such as grooves that fill with snow
taken in
from the roadway. It is known here from WO 2018/103924 Al that circumferential
grooves with a depth of 1.5 mm to 2.5 mm and a width of 2.0 to 3.0 times this
depth
1
CA 03197350 2023- 5-3
202006001
PCT/DE2021/200254
quickly and reliably fill with snow when driving on a snow-covered roadway.
Fast
filling of a structure in the profile of the pneumatic vehicle tire with snow
in order to
generate snow-on-snow friction is particularly important if a vehicle has an
anti-slip
control (ASR) system or an anti-lock (ABS) system, because the profile of the
pneumatic vehicle tire then grips the roadway after short slip distances or
short
gripping times, and snow-on-snow friction is then required for this purpose.
[0007] The edge (shear) action of the profile structure is achieved using
sipes, also
referred to as lamellae, at regular spacing intervals in the profile. The
width of these
sipes is smaller than the width of channels or grooves in the profile of the
tread of a
pneumatic vehicle tire, and amounts to between 0.2 mm and 0.7 mm, preferably
between 0.4 and 0.6 mm, and particularly preferably between 0.45 mm and 0.55
mm. The sipes are typically arranged in the profile blocks of the profile of
the tread,
which are formed by channels in the profile. If a profile block now passes
through
the ground contact patch of the pneumatic vehicle tire, that is to say the
profile block
makes contact with the roadway as the tire rotates, the sipes in the profile
block
open, resulting in grip edges that increase the traction in snow. Here, the
profile
block elements that are delimited by two sipes, or by a sipe and a profile
block edge,
tilt. The formation of grip edges, and the tilting of the profile block
elements, increase
with the depth of the sipes in the profile.
[0008] The depth TF of the sipes may however be reduced at the block edges,
for
example in order to improve the handling of the pneumatic vehicle tire. On the
other
hand, such structures of the sipes, referred to as edge elevations of the
sipes,
reduce the formation of grip edges and the tilting of the profile block
elements.
[0009] In the case of an ice-covered roadway, the tilting of the profile block
element
is however disadvantageous because, as a profile block passes through the
ground
contact patch, the contact area between the profile block elements present in
the
profile block and the ice-covered roadway is reduced as a result, such that
only a
reduced contact area can contribute to the traction between pneumatic vehicle
tire
and roadway.
[0010] This conflict of aims between snow performance and ice performance in
the
context of grip on snow and grip on ice can be allowed for by providing a band
profile
2
CA 03197350 2023- 5-3
202006001
PCT/DE2021/200254
in a circumferential rib of the profile of the pneumatic vehicle tire tread.
Here, the
circumferential rib runs once around the circumference of the tire and has a
fixed
position in an axial direction A of the pneumatic vehicle tire. The axial
direction A of
the pneumatic vehicle tire is in this case the direction of the axis about
which the
pneumatic vehicle tire mounted on a wheel rim rotates in a vehicle. Such a
circumferential rib is correspondingly delimited in the axial direction A by
two
circumferential channels. Those sides of said circumferential channels which
delimit
the circumferential rib then preferably run parallel to one another and
preferably run
in a circumferential direction perpendicular to the axial direction A. Those
sides of
the circumferential channels which delimit the circumferential rib, or the
edge of the
circumferential rib, then have/has no directional component in the axial
direction.
Here, the circumferential rib in the form of a band profile has sipes at
regular spacing
intervals in the circumferential direction. Since such a circumferential rib
has no
profile blocks that are separated by channels, in particular transverse
channels that
are transverse with respect to the circumferential direction, the rib elements
formed
in the circumferential rib by the sipes tilt to a reduced degree as said rib
elements
pass through the ground contact patch. On the other hand, the rib elements are
in
this case even supported so well that the sipes no longer open far wide enough
to
allow the grip edges that arise as a result to impart their full action on
snow. In the
case of such a circumferential rib, the snow-on-snow friction is also only
low, and is
based only on the circumferential channels of full profile depth that delimit
said
circumferential rib.
[0011 'The circumferential rib is positioned in the middle, and preferably
centrally, in
the axial direction A. A circumferential rib is situated in the middle if, in
the axial
direction A, there are further profile elements such as profile blocks
situated
between the circumferential rib and the tire shoulder situated closest to said
circumferential rib. A circumferential rib is a central circumferential rib if
it is
positioned centrally in the tread of the pneumatic vehicle tire in the axial
direction A,
and thus those sides of the two circumferential channels which delimit said
circumferential rib have the same spacing to the tire shoulder that is
situated closest
in the axial direction A.
[001211f, in such circumferential ribs, the sipes of the band profile have
edge
elevations at the edge of the circumferential rib, which edge elevations are
situated
3
CA 03197350 2023- 5-3
202006001
PCT/DE2021/200254
in succession in the circumferential direction, this leads to increased
circumferential
stiffness of the circumferential rib at its edges, increasing wear in this
region of the
circumferential rib.
[0013]EP 3 444 129 Al has disclosed middle circumferential ribs with improved
snow-on-snow friction, with a band profile in which straight sipes and
channels,
which are angled relative to the axial direction A, alternate in a
circumferential
direction, and the channels additionally have a bevel at their ends.
[0014]US 2020/0031171 Al has disclosed a central circumferential rib which, at
regular spacing intervals in a circumferential direction, has straight sipes
which are
angled relative to the axial direction A, wherein, at eight times the length
of the
spacing interval of the sipes in the circumferential direction, a thin
transverse
channel is arranged in the central circumferential rib in place of a sipe,
which thin
transverse channel is angled to the same degree relative to the axial
direction A.
Said transverse channels have, in their end regions, a depression with a
greater
depth than the transverse channel and with the same depth as the
circumferential
channels that delimit the circumferential rib. Those sides of said
circumferential
channels which delimit the circumferential rib have a zigzag shape relative to
the
axial direction A, and do not run parallel to one another.
[0015]US 2018/0345734 Al has disclosed middle circumferential ribs of a
pneumatic vehicle tire with good snow and ice performance, which, at regular
spacing intervals in a circumferential direction, have straight sipes which
are angled
relative to the axial direction A, wherein, at five times the length of the
spacing
interval of the sipes in the circumferential direction, a thin transverse
channel is
arranged in the middle circumferential rib in place of a sipe, which thin
transverse
channel is angled to the same degree relative to the axial direction A. These
transverse channels have, in their end regions, a depression with a greater
depth
than the transverse channel in the middle of the circumferential rib.
[0016]EP 3 421 263 B1 has disclosed middle circumferential ribs of a pneumatic
vehicle tire with good snow performance, which middle circumferential ribs
have, at
regular spacing intervals in a circumferential direction, straight sipes that
are angled
4
CA 03197350 2023- 5-3
202006001
PCT/DE2021/200254
relative to the axial direction A, wherein part of every second sipe is
replaced by a
transverse channel that is deeper than the sipes.
[0017]US 2018/0290498 Al has disclosed circumferential ribs in the shoulder
region of a pneumatic vehicle tire, which circumferential ribs have sipes at
regular
spacing intervals in a circumferential direction, wherein, in the case of
every fifth
sipe in the circumferential direction, the end regions have a channel portion
that has
a greater width than the sipe and a greater depth than the sipe. The channel
portions
are provided for filling with snow when driving on a snow-covered roadway.
[0018] Despite the profile structures that are already known, the problem
addressed
remains that of even more effectively resolving the conflict between snow and
ice
performance, whilst allowing for reduced tire wear resulting from abrasion.
Summary of the invention
(0019] The object is achieved by a pneumatic vehicle tire as claimed in claim
1.
[0020]Such a pneumatic vehicle tire has a tread which has a profile and has a
middle circumferential rib delimited by two sides, running at least
approximately
parallel to one another, of two circumferential channels which encircle the
entire
pneumatic vehicle tire, which circumferential channels run at least
approximately
perpendicular to the axial direction A of the pneumatic vehicle tire in that
they only
deviate by an angle y of less than 15 from the radial direction of a plane
perpendicular to the axial direction A, such that the width of the
circumferential rib
thus remains constant or increases with increasing profile depth, wherein the
circumferential rib has, at regular spacing intervals d in a circumferential
direction,
a sipe which runs from one to the other of the mutually parallel sides of the
two
encircling circumferential channels along a contour line, and wherein, at
three to
seven times the length of the spacing interval d of the sipes in the
circumferential
direction, in each case one thin transverse channel is arranged in the middle
circumferential rib in place of a sipe, the width BQ of which thin transverse
channel
is at least 2.5 times the width BF of a sipe and which thin transverse channel
has
the contour line of the sipes, and wherein the depth TF of the sipes is at
least partially
reduced, over a length Lred of the contour line, in the end regions of the
sipes, and,
CA 03197350 2023- 5-3
202006001
PCT/DE2021/200254
over 80% to 250% of said length Lred of the contour line, the thin transverse
channels
have in their end regions a snow pocket which has a width Bs perpendicular to
the
contour line of at least 1.5 times the width Bq of the thin transverse channel
and has
a depth Ts of at most 65% of the profile depth To of the thin transverse
channel.
(0021]A pneumatic vehicle tire according to the invention thus has a tread
with a
profile that has two circumferential channels that encircle the entire tire.
The two
circumferential channels are adjacent circumferential channels, between which
a
middle circumferential rib is situated in the tread.
[0022] Each circumferential channel of a pneumatic vehicle tire now has two
sides
in the axial direction A of the pneumatic vehicle tire, if one considers the
cross
section thereof perpendicular to the circumferential direction. In relation to
the lowest
point of the cross section of the circumferential channel, the spacing of
which to the
surface of the tread corresponds to the profile depth of the pneumatic vehicle
tire,
the two sides are situated on one or the other side of the lowest point of the
cross
section in the axial direction A. Here, the two sides of the circumferential
channel
delimit a circumferential rib composed of the rubber material of the tread.
The sides,
facing toward one another, of two adjacent encircling circumferential channels
then
jointly delimit a circumferential rib of the profile of the tread.
[0023] In a pneumatic vehicle tire according to the invention, those sides of
the two
circumferential channels which delimit the circumferential rib run at least
approximately parallel to one another and at least approximately perpendicular
to
the axial direction A of the pneumatic vehicle tire. Here, the sides that
delimit the
circumferential rib only deviate by an angle y of less than 150 from the
radial direction
of a plane perpendicular to the axial direction A. This deviation of the sides
that
delimit the circumferential rib is such that the width of the circumferential
rib remains
constant or increases with increasing profile depth. The two sides that
delimit the
circumferential rib thus run parallel to the circumferential direction of the
pneumatic
vehicle tire and have only the small deviation, defined by the angle y, from
the radial
direction of the pneumatic vehicle tire. The radial direction of the pneumatic
vehicle
tire is perpendicular to the axial direction A thereof, about which said
pneumatic
vehicle tire rotates. Inwardly along the radial direction, that is to say in
the direction
of the middle of the pneumatic vehicle tire, the profile depth of the tire
profile
6
CA 03197350 2023- 5-3
202006001
PCT/DE2021/200254
increases. The sides that delimit the circumferential rib now deviate from the
radial
direction of the pneumatic vehicle tire by the angle y such that the width of
the
circumferential rib remains constant or increases with increasing profile
depth, that
is to say inwardly. The circumferential rib then correspondingly has a
constant width
B in the axial direction A, at the surface and at every profile depth, over
the entire
circumference of the pneumatic vehicle tire according to the invention, said
width
being defined by the spacing of the at least approximately parallel sides in
the axial
direction, though said width may increase inwardly in accordance with the
angle y,
which varies with the profile depth. In one preferred embodiment, the two
sides,
which delimit the circumferential rib, of the two parallel circumferential
channels are
situated in two parallel planes that are perpendicular to the axial direction
A. Then,
other than in the bottom region of the circumferential channels, the angle y
is 0 over
the profile depth, and the width B is constant over the profile depth of the
profile. In
one particularly preferred embodiment, the two circumferential channels
themselves, which delimit the circumferential rib, also run parallel to one
another in
two planes perpendicular to the axial direction A, that is to say the lowest
point of
the cross section of the circumferential channels perpendicular to the
circumferential
direction is situated, over the entire tire circumference, in in each case one
of the
two planes perpendicular to the axial direction A. Here, the two
circumferential
channels particularly preferably both have the same width in the axial
direction A
over the entire tire circumference. Here, pure manufacturing tolerances in the
production of the tire profile are not taken into consideration with regard to
the design
of the circumferential channels.
[0024]Typically, the width B in the axial direction A of the circumferential
rib at the
surface thereof is 17 mm to 40 mm, preferably 20 mm to 30 mm, and particularly
preferably 22 mm to 28 mm, in the new state of the pneumatic vehicle tire.
[0025] Here, the circumferential rib has sipes at regular spacing intervals d
in the
circumferential direction. The sipes present in the circumferential rib run
from one
to the other of the mutually parallel sides, which delimit the circumferential
rib, of the
two encircling circumferential channels along a contour line. The sipes thus
run from
one end of the circumferential rib in the axial direction A, which is formed
by one
side of one of the two encircling circumferential channels, to the other end
of the
circumferential rib in the axial direction A, which is formed by one side of
the second
7
CA 03197350 2023- 5-3
202006001
PCT/DE2021/200254
of the two encircling circumferential channels. Here, all of the sipes run
along a fixed
contour line which likewise runs from one end of the circumferential rib in
the axial
direction A to the other end of the circumferential rib in the axial direction
A. The
contour line defines the course of the sipes at the surface of the tread
irrespective
of the circumferential position of the sipe. The contour line is in this case
merely the
main line along which the sipes run from one end of the circumferential rib to
the
other end of the circumferential rib. The actual course of the sipe at the
surface of
the tread may deviate from this main line, because the main line may in this
case
also have added to it a course of the sipe which, substantially in the surface
of the
tread, has a component perpendicular to the main line, that is to say which,
in the
surface of the tread, runs primarily perpendicular to the contour line. Here,
the
dimension of the deviation from the main line is considerably smaller than the
width
B of the circumferential rib in the axial direction A. Typically, the
dimension of the
deviation is at most 15% of the width B of the circumferential rib, preferably
at most
5% of the width B of the circumferential rib and particularly preferably 3% of
the
width B of the circumferential rib. The course thus added has its main
component,
that is to say its main course direction, in a direction that typically
deviates by no
more than 20 from the perpendicular to the contour line in the surface of the
tread,
preferably deviates by no more than 50 from the perpendicular to the contour
line on
the surface of the tread, and particularly preferably deviates by no more than
2 from
the perpendicular to the contour line on the surface of the tread. The added
course
typically oscillates or meanders in the direction of the main component about
the
contour line, or in this direction has a zigzag course or some other periodic
course,
wherein the period may vary along the contour line. The added course is
preferably
present only over a part of the contour line. The sipes extend in a radial
direction of
the pneumatic vehicle tire from the surface of the circumferential rib to a
depth TF,
whilst following their course at the surface of the tread. Here, sipes which
are
adjacent in the circumferential direction have approximately the same spacing
interval dn in the circumferential direction, and preferably run parallel to
one another.
The spacing interval dn of adjacent sipes in the circumferential direction
typically
varies here, over the entire circumference of the tire, by at most 10% of the
average
spacing interval d, preferably by at most 5% of the average spacing interval d
and
particularly preferably by at most 2% of the average spacing interval d. This
is based
in particular only on manufacturing tolerances during the course of the
production
of the pneumatic vehicle tire. Typically, the regular spacing interval d of
the sipes in
8
CA 03197350 2023- 5-3
202006001
PCT/DE2021/200254
the circumferential direction at the surface of the circumferential rib in the
new state
of the pneumatic vehicle tire is 3 mm to 9 mm, preferably 4 mm to 7 mm, and
particularly preferably 5 mm to 6 mm.
[0026]At three to seven times the length of the spacing interval d of the
sipes in the
circumferential direction, in each case one thin transverse channel is
arranged in
the circumferential rib of the pneumatic vehicle tires according to the
invention in
place of these sipes. These thin transverse channels may each be arranged in
the
circumferential channel with uniform spacing intervals, or preferably with
different
spacing intervals, in the circumferential direction, wherein the spacing of
the thin
transverse channels in the circumferential direction is in each case a
multiple of the
spacing interval d of the sipes in the circumferential direction. Improved
acoustic
behavior of the pneumatic vehicle tire according to the invention is achieved
with an
arrangement of the thin transverse channels with different spacings in the
circumferential direction, because vibrations owing to a particular resonance
period
in the circumferential direction are thereby avoided owing to the thin
transverse ribs
in the circumferential rib.
[0027]The width BQ of the thin transverse channel in the middle
circumferential rib
of the pneumatic vehicle tire according to the invention is at least 2.5 times
the width
BF of a sipe in the middle circumferential rib, preferably 2.5 to 5 times the
width BF
of a sipe, particularly preferably 2.75 to 4.5 times the width BE of a sipe,
and most
preferably 2.8 to 4 times the width BE of a sipe. The width BQ of the thin
transverse
channels and the width BE of the sipes is the width perpendicular to the
common
contour line of the thin transverse channels and sipes.
[0028]Specifically, the thin transverse channels in the middle circumferential
rib of
the pneumatic vehicle tire according to the invention have the contour line of
the
sipes. In this way, the transverse channels and sipes of the middle
circumferential
rib have substantially the same shape at the surface of the tread of a vehicle
tire
according to the invention. The thin transverse channels thus follow the same
contour line as the sipes. Here, the contour line of a thin transverse channel
and
that of an adjacent sipe run parallel to one another so as to be offset in the
circumferential direction by the spacing interval d. It is essential that each
thin
transverse channel runs along the contour line and cannot also, like a sipe,
have an
9
CA 03197350 2023- 5-3
202006001
PCT/DE2021/200254
added course that substantially has a component perpendicular to the contour
line.
The thin transverse channels extend in a radial direction of the pneumatic
vehicle
tire from the surface of the circumferential rib to a depth TQ, whilst
following their
course at the surface of the tread.
[0029] The depth TF of the sipes of the middle circumferential rib of the
pneumatic
vehicle tire according to the invention is at least partially reduced, over a
length Lred
of the contour line, in the end regions of the sipes. The depth TF of such a
sipe is
thus limited to a reduced depth TF,1 in one end region or both end regions of
the
sipe, which are adjacent to the two circumferential channels that delimit the
circumferential rib. Such a sipe then has one edge elevation or two edge
elevations.
It is possible for only some of the sipes or for all of the sipes of the
middle
circumferential rib to have one or two such edge elevations. The reduction of
the
depth TF may be the same or different for all sipes with an edge elevation.
The length
Lred Of the contour line in which an edge elevation is present begins in each
case at
one end of the surface of the circumferential rib in the axial direction A,
that is to say
at one of the two sides of one of the two circumferential channels that
delimit the
circumferential rib, and then ends at a particular point of the contour line.
[0030] Over an approximately equal or greater length Ls, specifically over 80%
to
250% of said length Lred of the contour line, the thin transverse channels of
the
circumferential rib have a snow pocket in their end regions. Such a snow
pocket at
the ends of the thin transverse channel thus extends over said length Ls along
the
contour line, likewise beginning at one of the two sides of one of the two
circumferential channels that delimit the circumferential rib. The task of
such a snow
pocket, which constitutes a cavity in the tire profile, is to quickly fill
with snow from
the roadway during driving operation, such that increased grip on snow is
achieved,
owing to snow-on-snow friction, correspondingly quickly.
[0031] Here, the snow pockets at the ends of the thin transverse channels have
a
width Bs perpendicular to the contour line of the thin transverse channels,
and
measured parallel to the tire surface on which the contour line runs, of at
least 1.5
times the width Bo of the thin transverse channel, and a depth Is of at most
65% of
the profile depth TQ of the thin transverse channel. The further geometrical
dimensions of the snow pockets provided in the middle circumferential rib of a
CA 03197350 2023- 5-3
202006001
PCT/DE2021/200254
pneumatic vehicle tire according to the invention are thus coupled to the
dimensions
of the thin transverse channels in the circumferential rib. Said snow pockets
are
wider than the thin transverse channels, specifically at least 1.5 times the
width of
the thin transverse channels, perpendicularly with respect to the contour line
of the
thin transverse channels, which is indeed also the contour line of the sipes.
By
contrast, the depth TS of said snow pockets is smaller than the profile depth
To of
the thin transverse channel, specifically such that the depth TS of said snow
pockets
amounts to at most 65% of the profile depth To of the thin transverse channel.
Here,
the depth TS of the snow pockets and the profile depth To of the thin
transverse
channels respectively denotes the extent of the snow pockets or thin
transverse
channels in the radial direction of the pneumatic vehicle tire proceeding from
the
surface of the tread of the pneumatic vehicle tire. Here, the radial direction
points
inward from the tire surface to the axis of rotation of the pneumatic vehicle
tire, and
is perpendicular thereto. Thus, in a middle circumferential rib of a pneumatic
vehicle
tire according to the invention, at the ends of thin transverse channels which
run
from one side of the circumferential rib to the other, there are provided snow
pockets
which, laterally, that is to say parallel to the tire surface, have an extent
defined by
a length LS along the contour line of the associated thin transverse channel
and by
a width Bs perpendicular to the contour line. Here, the width Bs is
intentionally made
greater than the width Bo of the thin transverse channel, and the length LS is
chosen
to be of a similar dimension to, or to be greater to a certain extent than,
the length
Lred of the edge elevations of the sipes of the circumferential rib.
Altogether, the
snow pockets thus have, at the tire surface, a large cross-sectional area that
can fill
with snow during driving operation on a snow-covered roadway. Furthermore, the
limited depth TS of the snow pockets results in fast filling of the snow
pocket with
snow, such that increased grip on snow owing to snow-on-snow friction is made
possible quickly. Such grip is particularly advantageous if a vehicle has an
anti-slip
control (ASR) or anti-lock (ABS) system and is thus capable of quickly
utilizing the
improved friction.
[0032] Furthermore, a length LS of the snow pockets that amounts to over 80%
to
250% of the length Lred of the edge elevations of the sipes along the contour
line
has approximately the same dimension as the length Lred of the edge
elevations, or
is greater than the length Lred of the edge elevations. The snow pockets are
thus
intentionally positioned at the same position as the edge elevations of the
sipes in
11
CA 03197350 2023- 5-3
202006001
PCT/DE2021/200254
an axial direction, because the snow pockets, as cavities, thus counteract
stiffening
of the circumferential rib at this axial position, that is to say at its ends
in the axial
direction A, caused by the edge elevations, and thus the circumferential
stiffness,
that is to say the elasticity of the circumferential rib, is made more uniform
in the
axial direction A. This is conducive to more uniform wear of the tread of a
pneumatic
vehicle tire according to the invention. This homogenization is based on all
dimensions of the snow pockets, that is to say not only their length Ls but
also their
width Bs and their depth Is.
[0033]Through the described provision of exactly defined snow pockets in the
profile structure of a middle circumferential rib with uniform sipes, which
are in part
replaced by thin transverse channels, it is thus possible for both the snow-on-
snow
friction of a pneumatic vehicle tire, and at the same time the wear behavior
of the
pneumatic vehicle tire, to be improved.
[0034] In one preferred embodiment, the middle circumferential rib of the
pneumatic
vehicle tire according to the invention is its central circumferential rib. In
this position,
the circumferential rib is at least normally in direct contact with the
roadway during
driving operation, such that the snow pockets of the circumferential direction
then
quickly fill with snow with the greatest certainty in the case of a snow-
covered
roadway, with snow-on-snow friction being established correspondingly quickly.
[0035]1n another embodiment, the thin transverse channels are, in the
circumferential direction, arranged in the middle circumferential channel of
the
pneumatic vehicle tire according to the invention in place of a sipe over
different
multiples of the spacing interval d of the sipes in the circumferential
direction.
Through this arrangement of the thin transverse channels at different spacing
intervals over the tire circumference, wherein the sequence of the different
multiples
may nevertheless periodically repeat over the tire circumference, the acoustic
behavior of the pneumatic vehicle tire according to the invention is improved,
as
already discussed above. The sequence of the multiples may for example consist
of exactly two different multiples, for example four times and five times,
which repeat
irregularly or regularly. In this example, it is then the case that every
fourth or fifth
sipe is replaced by a thin transverse channel which, at its ends, has a snow
pocket
with the above-described dimensions.
12
CA 03197350 2023- 5-3
202006001
PCT/DE2021/200254
[0036] In one preferred embodiment, at four to six times the length of the
spacing
interval d of the sipes in the circumferential direction, particularly
preferably at four
to five times the length of the spacing interval d of the sipes in the
circumferential
direction, the above-described thin transverse channel with its snow pockets
is
arranged in the middle circumferential rib of a pneumatic vehicle tire
according to
the invention in place of a sipe. In particular, with these spacing intervals
of the thin
transverse channels, tilting of the profile block elements in an appropriate
form is
achieved in order to realize both advantageous snow performance and
advantageous ice performance owing to the circumferential rib.
[0037] Preferably, in the middle circumferential rib of a pneumatic vehicle
tire
according to the invention, the width Bo of the thin transverse channels is at
most 5
times the width BF of a sipe. This, too, assists the tilting of the profile
block elements
in an appropriate form and prevents excessive tilting of individual profile
block
elements.
[0038] The snow pockets of the thin transverse channels of the middle
circumferential rib of a pneumatic vehicle tire according to the invention are
preferably arranged symmetrically with respect to the contour line of the thin
transverse channels. This is conducive to uniform tilting of the profile block
elements
that are adjacent to the thin transverse channel.
[0039] The snow pockets of the thin transverse channels of the middle
circumferential rib of a pneumatic vehicle tire according to the invention
preferably
have a width Bs perpendicular to the contour line of 2 to 3 times the width Bo
of the
thin transverse channel. The width BS of the snow pockets is particularly
preferably
2.2 to 2.5 times the width BQ of the thin transverse channel. This is
conducive to
good snow-on-snow friction, at the same time with appropriate tilting of the
profile
block elements and uniform elasticity of the middle circumferential rib in the
axial
direction A.
[0040] The snow pockets of the thin transverse channels of the middle
circumferential rib of a pneumatic vehicle tire according to the invention
preferably
have a depth Ts of 35 to 60% of the profile depth To of the thin transverse
channel,
particularly preferably 40% to 58% of the profile depth To of the thin
transverse
13
CA 03197350 2023- 5-3
202006001
PCT/DE2021/200254
channel, and very particularly preferably 50% to 55% of the profile depth of
the thin
transverse channel. This, too, is conducive to good snow-on-snow friction
after a
short time, at the same time with appropriate tilting of the profile block
elements and
uniform elasticity and thus uniform tire wear of the middle circumferential
rib in the
axial direction A.
[0041 I The thin transverse channels of the middle circumferential rib of a
pneumatic
vehicle tire according to the invention preferably had a snow pocket of length
Ls in
their end regions over 95% to 200% of the length Lred of the contour line over
which
the depth TF of the sipes is reduced in the end regions of the sipes, and said
thin
transverse channels particularly preferably had a snow pocket of length Ls
over
105% to 130% of the length Led of the contour line over which the depth of the
sipes
is reduced in the end regions of the sipes. In particular, the correspondence
between
the position of the elevations of the sipes and the position of the snow
pockets is
conducive to highly uniform elasticity, in the axial direction A, of the
middle
circumferential rib in the axial direction A. There is then in particular also
approximately the same circumferential stiffness at the sides of the
circumferential
rib, despite the elevations of the sipes, as in the middle of the
circumferential rib. As
a result, the wear of the rubber material of the circumferential rib is also
at least
approximately uniform over the entire width of the circumferential rib in the
axial
direction.
[0042] The thin transverse channels of the middle circumferential rib of a
pneumatic
vehicle tire according to the invention preferably have a snow pocket in their
end
regions over a length Ls of the contour line of 2.5 mm to 8 mm, particularly
preferably
over a length Ls of the contour line of 3.5 mm to 7 mm and very particularly
preferably over a length of the contour line of 4 mm to 5.5 mm. Here, both
good
snow-on-snow friction and highly uniform elasticity of the middle
circumferential rib
in the axial direction A are achieved.
[0043] The snow pockets of the thin transverse channels of the middle
circumferential rib of a pneumatic vehicle tire according to the invention
have a
bottom region and side faces. The bottom region delimits the snow pockets in a
radial direction at a depth Ts. Here, the depth Ts may however vary by up to
20%,
preferably by up to 5% and particularly preferably by up to 1%, in the axial
direction
14
CA 03197350 2023- 5-3
202006001
PCT/DE2021/200254
and circumferential direction. The side faces delimit the snow pockets by way
of
faces which extend from the bottom face to the surface of the pneumatic
vehicle
tire. In particular, a side face may in this case run parallel to the contour
line or, as
an end face of the snow pocket, be perpendicular to the contour line. The face
of
the bottom region of the snow pockets preferably transitions with a curvature
radius
of 0.2 mm to 1.5 mm, particularly preferably with a curvature radius of 0.5 mm
to
1.25 mm, and very particularly preferably with a curvature radius of 0.8 mm to
1.1
mm, into the side faces. This further improves the fast filling of the snow
pockets
with snow during driving operation on snow, which correspondingly leads more
quickly to good snow-on-snow friction.
[0044] In one embodiment, the snow pockets of the thin transverse channels of
the
middle circumferential rib of a pneumatic vehicle tire according to the
invention have
a bottom region and an end face as a side face. The face of the bottom region
typically transitions with a curvature radius of 0.2 mm to 1.5 mm, preferably
with a
curvature radius of 0.5 mm to 1.25 mm, and particularly preferably with a
curvature
radius of 0.8 mm to 1.1 mm, into the end face. This further improves the fast
filling
of the snow pockets with snow during driving operation on snow, which
correspondingly leads more quickly to good snow-on-snow friction.
[0045]Typically, the snow pockets of the thin transverse channels of the
middle
circumferential rib of a pneumatic vehicle tire according to the invention
have a
bottom region that continues inward in a radial direction, that is to say in
the direction
of the middle of the pneumatic vehicle tire, with a sipe along the contour
line. This
promotes the tilting of the profile block elements in the circumferential rib,
in
particular the tilting of the profile block elements adjacent to the
respective
transverse channel, which is thus not reduced by the depth Ts of the snow
pockets
being reduced in relation to the profile depth To of the thin transverse ribs.
[0046] Here, the sipes in the bottom region of the snow pockets typically have
the
same width BF as those sipes of the circumferential rib which have not been
replaced by a thin transverse channel. This further promotes uniform tilting
of the
profile block elements over the circumference, and the uniformity of the
elasticity of
the circumferential rib in the axial direction A.
CA 03197350 2023- 5-3
202006001
PCT/DE2021/200254
[0047] The sipes in the bottom region of the snow pockets preferably have the
same
depth TF as those sipes of the circumferential rib which have not been
replaced by
a thin transverse channel have in the middle of the circumferential rib. This,
too,
further promotes uniform tilting of the profile block elements over the
circumference,
and the uniformity of the elasticity of the circumferential rib in the axial
direction.
[0048] In one embodiment, the contour line of the sipes of the middle
circumferential
rib of a pneumatic vehicle tire according to the invention is a straight line,
which is
preferably perpendicular to the parallel sides of the two encircling
circumferential
channels.
[0049] In one embodiment, the contour line of the sipes of the middle
circumferential
rib of a pneumatic vehicle tire according to the invention is angled slightly
in the
middle of the circumferential rib. In this case, the contour line may thus be
formed
by two straight lines which are angled relative to one another and which
enclose an
angle 8 of 140 to 170 , preferably an angle 13 of 150 to 165 .
[0050] In particular embodiments of a pneumatic vehicle tire according to the
invention, the contour line of the sipes in the end region of the sipes
deviates from
the axial direction A of the pneumatic vehicle tire by an angle a of less than
20 ,
preferably less than 15 and particularly preferably less than 8 .
[005111n particular embodiments of a pneumatic vehicle tire according to the
invention, the sipes, running along the contour line, of the middle
circumferential rib
are of undulating form over a part of the contour line. In this part of the
contour line,
the actual course of the sipe deviates from the main line of the contour line.
The
course of the sipe has added to it an undulating component perpendicular to
the
contour line. Instead of the undulating component, the course of the sipe may
also
have added to it a zigzag line and some other oscillating component.
[0052] In particular embodiments, the depth TF of the sipes is partially
reduced, in
each case over a length Lred of the contour line of 7% to 35% in one end
region or
preferably both end regions of the sipes, preferably over in each case a
length Lred
of the contour line of 12% to 30%, and particularly preferably over a length
Lred of
16
CA 03197350 2023- 5-3
202006001
PCT/DE2021/200254
the contour line of 16% to 23%. The depth TF of all sipes is preferably
reduced over
such a length Lred of the contour line in both end regions of the sipes.
[0053] In other particular embodiments, the depth TF of the sipes is partially
reduced,
in each case over a length Lred of the contour line of 1.5 mm to 9 mm in one
end
region or preferably in both end regions of the sipes, preferably in each case
over a
length Lred of the contour line of 2.5 mm to 7.5 mm, and particularly in each
case
over a length Lred of the contour line of 3.5 mm to 5.5 mm. The depth TF of
all sipes
is preferably reduced over such a length Lred of the contour line in both end
regions
of the sipes.
(0054] In the abovementioned embodiments, the depth TF,1, TF,2 of the sipes in
their
end regions may be reduced to different extents in different sipes in order to
make
the circumferential stiffness more uniform in the circumferential direction.
In
particular, in sipes that are successive in the circumferential direction, the
depth TF
of the sipes in their end regions may be reduced alternately to a first depth
TF,1 and
a second depth TF,1-
[0055]Typically, the depth TF of the sipes of the middle circumferential rib
of a
pneumatic vehicle tire according to the invention is reduced in the end
regions by
25% to 85%, preferably by 35% to 75%, and particularly preferably by 40% to
55%.
(0056] In embodiments in which the depth TF,1, TF,2 of the sipes in their end
regions
is reduced to different extents in different sipes, the first depth TF,1 is
typically
reduced by 25% to 60% and the second depth TF,2 is typically reduced by 60% to
85%, preferably the first depth TF,1 is reduced by 35% to 55% and the second
depth
TF,2 is reduced by 65% to 80%, and particularly preferably the first depth
TF,1 is
reduced by 40% to 50% and the second depth TF,2 is reduced by 70% to 75%. This
promotes the uniformity of the elasticity of the circumferential rib in the
circumferential direction at its sides.
Brief description of the drawings
[0057]The invention will now be explained in more detail on the basis of an
exemplary embodiment, in which:
17
CA 03197350 2023- 5-3
202006001
PCT/DE2021/200254
figure 1:
shows a detail of the surface of a tread of a pneumatic vehicle tire
according to the invention across the entire width of the tread
figure 2: shows a detail of the central circumferential rib of the
pneumatic
vehicle tire according to the invention shown in figure 1, in a
circumferential direction
figure 3: shows a 3-dimensional detail of the profile of the central
circumferential rib of the pneumatic vehicle tire according to the
invention shown in figure 1
Detailed description of the invention
(0058] Figures 1 to 3 show an exemplary embodiment of a pneumatic vehicle tire
according to the invention. A pneumatic vehicle tire of said type has a tread
that is
equipped with a profile. Figure 1 shows a detail of the surface of the tread 1
of the
pneumatic vehicle tire according to the invention across its entire width.
Visible in
the profile of the tread 1 are various profile elements, with a
circumferential rib 3, a
central circumferential rib, being shown in the middle of the tread 1. Said
circumferential rib 3 extends in a direction of revolution over the entire
circumference
of the pneumatic vehicle tire according to the invention and is delimited by
two
circumferential channels 2, 2' that encircle the entire circumference of the
pneumatic
vehicle tire according to the invention. The two circumferential channels 2,
2' run
parallel to one another and run perpendicular to the axial direction A of the
pneumatic vehicle tire. Both circumferential channels 2, 2' have the same
cross
section, perpendicular to the circumferential direction, over the entire tire
circumference. Here, both circumferential channels 2, 2' have two sides that
delimit
the two circumferential channels 2, 2' in the axial direction A. In each case
one of
the two sides 4, 4' of the circumferential channels 2, 2' delimits the
circumferential
rib 3. A detail of the circumferential rib 3 in a circumferential direction is
likewise
shown in figure 2. Said figure likewise shows the circumferential channels 2,
2' that
delimit the circumferential rib 3, with their sides 4, 4' that delimit the
circumferential
rib 3. Figure 3 likewise shows the circumferential rib 3, this time in a three-
dimensional illustration, with the circumferential rib 3 itself being shown in
a
developed view in a plane, as in figure 2. Here, in particular, a view of the
circumferential rib 3 in an axial direction A is shown, with a short detail of
the
circumferential rib 3 in a circumferential direction U being shown. Here, too,
it is
18
CA 03197350 2023- 5-3
202006001
PCT/DE2021/200254
possible to see the circumferential channels 2 and 2' that delimit the
circumferential
rib 3. Only in the case of the circumferential channel 2 at the bottom of the
illustration
is it also possible to see the side 4 of the circumferential channel 2, which
side forms
the edge of the circumferential rib 3. The sides 4, 4', which delimit the
circumferential
rib 3, of the circumferential channels 2,2' run in two parallel planes
perpendicular to
the axial direction A. The straight sides 4, 4' are thus perpendicular to the
tread
surface and extend along the circumferential direction. The spacing of the
sides 4,
4' in the axial direction A then predefines a width B of the circumferential
rib 3 which
is constant in a radial direction of the tire, and which in the exemplary
embodiment
is 27 mm. The sides 4, 4' then transition, with a curvature in the bottom
region of the
circumferential channels 2, 2', into the channel base of the circumferential
channels
2, 2', as shown in figure 3.
(0059] The circumferential rib is divided by sipes 6 which run across the
entire width
B of the circumferential rib 3 from one to the other of the mutually parallel
sides 4,
4' of the two encircling circumferential channels 2, 2'. The sipes 6 have a
regular
spacing interval d to one another in the circumferential direction U, which in
the
exemplary embodiment is 5.5 mm at the surface of the circumferential rib 3.
Here,
each sipe 6 runs along a contour line 10. The shape of the contour line 10 is
the
same for all sipes 6 in the circumferential rib 3. The contour line 10 is
formed by two
straight lines which each enclose an angle a of 15 with the axial direction A
and
which intersect in the middle of the circumferential rib 3. Correspondingly,
the two
straight lines enclose an angle 8 of 150 with one another. Other than in the
edge
regions of the circumferential rib 3, an undulating line is superposed on said
contour
line 10 in the course of the sipes 6, such that the sipes 6 have an undulating
course
in the middle of the circumferential rib 3. Whilst the profile depth of the
circumferential channels 2, 2' in the new state of the pneumatic vehicle tire
is 8 mm,
the depth TF of the sipes 6 in the middle of the circumferential rib 3 is 7
mm. In the
end region of the sipes 6, the depth IF of the sipes 6 is reduced. In the
exemplary
embodiment, the depth TF is reduced at both end regions over 21% of the length
Lred Of the contour line 10. In the exemplary embodiment, the depth TF of the
contour
line is reduced over the length Lred of 5.5 mm along the contour line 10.
Every second
sipe 6 has a depth TF,1 of only 1.75 mm in its end region. The depth TF,2 of
the other
sipes is reduced in the end regions to 50% of the profile depth TF, and is
therefore
3.5 mm, over the same length Lred.
19
CA 03197350 2023- 5-3
202006001
PCT/DE2021/200254
[0060]In the circumferential rib 3, the sipes 6 are replaced at certain
spacing
intervals in the circumferential direction U by a thin transverse channel 8.
In the
exemplary embodiment shown, this spacing interval amounts alternately to four,
five
or six times the length of the spacing interval d of the sipes 6, in an
irregular
sequence. Here, the thin transverse channels 8 are arranged at irregular
spacing
intervals in order to avoid vibrations of the circumferential rib 3 owing to
resonance
that can result from a regular spacing of the thin transverse channels 8. In
the
exemplary embodiment, the width BQ of the thin transverse channels 8 is three
times
the width BE of the sipes 6. In the exemplary embodiment, the width BE of the
sipes
6 is 0.5 mm, and the width BQ of the thin transverse channels 8 is
correspondingly
1.5 mm. The profile depth TQ of the thin transverse channels is 8 mm. The
transverse
channels 8 run along the same contour line 10 as the sipes 6. Here, the sipes
8 run
only along the contour line 10 and have no further component perpendicular to
the
contour line, as in the case of the undulating course of the sipes 6.
[0061] Furthermore, the thin transverse channels 8 each have a snow pocket 20
in
their end regions. Here, the end region of the contour line 10 that extends
from one
circumferential channel 2 to the other circumferential channel 2', which
circumferential channels delimit the circumferential rib 3, is that region of
the contour
line 10 which begins in each case at the circumferential channels 2 and 2' and
then
extends inward into the circumferential rib 3. Here, the snow pockets 20 then
have
a length LS along the contour line 10. In the exemplary embodiment, the snow
pockets 20 have a length LS equal to the length Led of the elevations of the
sipes 6.
Correspondingly, the length LS of the snow pockets also amounts to 21% of the
length of the contour line 10. Furthermore, the snow pockets 20 also have an
extent
parallel to the surface of the tread 1 perpendicularly with respect to the
contour line
10. In the exemplary embodiment, this width BS of the snow pockets 20 is twice
the
width BQ of the thin transverse channels 8, and is therefore 3 mm.
Furthermore, the
snow pockets 20 also have a depth TS in a radial direction. In the exemplary
embodiment, the depth TS of the snow pockets 20 is exactly half the profile
depth
TQ of the thin transverse channels 8. Correspondingly, the profile depth Ts of
the
snow pockets has a value of 4 mm. Further details of the design of the snow
pockets
20 can be seen in particular from figure 3. At the depth Ts, the snow pockets
20
have a bottom region 21. In the exemplary embodiment shown, said bottom region
21 is substantially parallel to the surface of the tread 1. The snow pockets
20
CA 03197350 2023- 5-3
202006001
PCT/DE2021/200254
furthermore have side faces 22. In the exemplary embodiment shown, the side
faces
22 firstly run parallel to the contour line 10 and perpendicular to the
surface of the
tread 1, such that the surfaces have a component in a radial direction.
Furthermore,
one side face 22 of the snow pockets is configured as an end face 23, which is
a
face perpendicular to the contour line 10. Between the bottom region 21 and
the
side faces 22, in particular the end face 23, there is a transition with a
curvature
radius of 1 mm. Furthermore, the bottom region 21 of the snow pockets 20 has,
in
its middle, a sipe 25 that runs along the contour line 10 of the thin
transverse
channels 8. The width of the sipes 25 corresponds to the width BF of the sipes
6.
The depth of said sipes 25 corresponds to the depth TF of the other sipes 6 of
the
circumferential rib 3. As in all embodiments of the pneumatic vehicle tire
according
to the invention, the central circumferential rib 3 of the exemplary
embodiment is
distinguished by the fact that, owing to the snow pockets 20 that are
provided, said
central circumferential rib exhibits good snow-on-snow friction, which is
available
after a short time because the snow pockets 20 fill up quickly, and
furthermore by
uniform tilting of the profile block elements that are provided, resulting in
a good
compromise between snow behavior (snow performance) and ice behavior (ice
performance) of the circumferential rib 3. The design of the snow pockets 20
furthermore allows very uniform elasticity or circumferential stiffness of the
transverse rib 3 in the axial direction A. Here, the snow pockets 20 that are
provided
at the edge of the circumferential rib 3 substantially compensate for the
elevations
at the end of the sipes 6 of the circumferential rib 3. The structure of a
middle
circumferential rib of the pneumatic vehicle tire according to the invention
has been
discussed in detail on the basis of the described parameters of this
description. This
structure must be correspondingly adapted in each case to the size of a
pneumatic
vehicle tire. In particular, the circumferential ribs 3 of the pneumatic
vehicle tires
according to the invention are used in pneumatic vehicle tires with a width of
between 195 mm and 315 mm. The height of the tire may in this case amount to
between 35% of the width of the pneumatic vehicle tire and 65% of the width of
the
pneumatic vehicle tire. The wheel rims on which such pneumatic vehicle tires
are
mounted can have a diameter of between 15 inches and 22 inches. A different
number of sipes 6 and thin transverse channels 8 may be provided over the
circumference of the pneumatic vehicle tire depending on the corresponding
circumference of such a tire. Here, a number of sipes 6 and transverse
channels 8
may increase with the circumference, or may increase with the circumference
only
21
CA 03197350 2023- 5-3
202006001
PCT/DE2021/200254
to a certain proportion. Such a proportion may for example be between 5 and
20%.
In general, pneumatic vehicle tires according to the invention may of course
also
have other dimensions, as long as the advantageous characteristics of the
described circumferential rib can be utilized in the pneumatic vehicle tire.
It is finally
pointed out that the invention has been discussed on the basis of numerous
detailed
exemplary embodiments. These are however examples of the invention. Other
embodiments of the pneumatic vehicle tire according to the invention may
correspondingly also have only individual features of an exemplary embodiment,
or
features of different described exemplary embodiments simultaneously, unless
explicitly stated otherwise.
22
CA 03197350 2023- 5-3
202006001
PCT/DE2021/200254
List of reference signs
1 Tread
2, 2' Circumferential channel
3 Circumferential rib
4, 4' Side of a circumferential channel
6 Sipe
8 Thin transverse channel
Contour line
Snow pocket
21 Bottom region of a snow pocket
22 Side face of a snow pocket
23 End face of a snow pocket
Sipe below a snow pocket
A Axial direction
B Width of the circumferential rib in axial direction A
BE Width of a sipe
BQ Width of the thin transverse channel
Bs Width of the snow pocket perpendicular to the contour line
d Spacing of the sipes in circumferential direction
dn Spacing of adjacent sipes in circumferential direction
Lmd Length of the contour line over which the depth of a sipe
is reduced
Ls Length of the snow pocket along the contour line
TF Depth of the sipes
TF,1 Reduced depth of a first sipe in the edge region
TF,2 Reduced depth of a second sipe in the edge region
TQ Depth of the thin transverse channel
Ts Depth of the snow pocket
U Circumferential direction
a Angle by which the contour line of the sipes in the end
region of the sipes
deviates from the axial direction A of the pneumatic vehicle tire
13 Angle enclosed between two straight lines which are at an
angle with respect
to one another and which form a contour line
23
CA 03197350 2023- 5-3
202006001
PCT/DE2021/200254
y
Angle by which the two sides of two encircling circumferential channels that
delimit the circumferential rib deviate in a radial direction from a plane
perpendicular to the axial direction A
24
CA 03197350 2023- 5-3
