Note: Descriptions are shown in the official language in which they were submitted.
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Description
Pneumatic vehicle tyre
The invention relates to a pneumatic vehicle tire
having a profiled tread with radially elevated profile
elements which are delimited by channels and having
sipes, which sipes are formed at least in some of the
profile elements and have in each case two parallel
sipe walls which delimit the sipe and which are formed
substantially correspondingly to one another, wherein
the first main direction of extent, which is formed in
the ground contact surface-forming outside surface of
the profile element, of the sipe has its greatest
directional component in the axial direction A of the
pneumatic vehicle tire, and wherein, in the section
planes perpendicular to the first main direction of
extent in the ground contact surface, the sipe extends
from the ground contact surface-forming outside surface
to the sipe base over a depth T of the sipe measured in
the radial direction R, and which sipes have a first,
radially outer region of extent which extends from the
ground contact surface-forming outside surface radially
inward over a height hl measured in the radial direction
R, where (1/2)T hl 0.9T, and
which sipes have a
second, radially inner region of extent which is formed
so as to adjoin the first region of extent inward in
the radial direction R and which extends over a height
h2, measured in the radial direction R, to the sipe
base, wherein, in the section planes perpendicular to
the first main direction of extent, the sipe, in each
case in the first, radially outer region of extent,
runs from the outside surface to the second, radially
inner region of extent so as to be aligned along a
second main direction of extent which has an angle of
inclination a with respect to the radial R, wherein 00
a < 30.
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Such pneumatic vehicle tires with sipes are known.
Here, the sipes extend with a first main direction of
extent substantially in the axial direction in the
outside surface of the profile element, and extend
perpendicular to said first main direction of extent,
in a second main direction of extent, substantially
rectilinearly inward in the radial direction to the
sipe base. It is also known for such sipes to run, in
their radial extent, in a zig-zagged or undulating
manner about a second main direction of extent in the
direction of the sipe base, wherein in the case of
these sipes, too, the radially inner region of extent
to the sipe base is formed so as to run rectilinearly
in the radial direction as an elongation of the second
main direction of extent.
In the case of all of said sipes, the respective
opening and closing sipe action with the associated
traction-improving characteristics is made possible,
but results in a stress concentration at the radially
inner channel sipe base, increased material loading in
the radially inner region of extent of the sipe, and an
increased notch effect. Said effects reduce the
durability of the profile elements.
It is the object of the invention to improve the
loadability and durability of such profiles in a simple
manner without restriction of the advantages of the
utilization of sipes.
The object is achieved according to the invention by
means of the design of a pneumatic vehicle tire having
a profiled tread with radially elevated profile
elements which are delimited by channels and having
sipes; said sipes being formed at least in some of the
profile elements, with each sipe having two parallel
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sipe walls which delimit the sipe and which are
complementary in shape to one another, wherein a first
main direction of extent, which is formed in a ground-
contacting outside surface of the profile element of
the sipe, has a greatest directional component in an
axial direction A of the pneumatic vehicle tire, and
wherein, in cross-sectional planes perpendicular to the
first main direction of extent in the ground-contacting
surface, the sipe extends from the ground-contacting
outside surface to a sipe base over a depth T of the
sipe, measured in a radial direction R; said sipes
having a first, radially outer region of extent, which
extends from the ground-contacting outside surface
radially inward over a height hl measured in the radial
direction R, where (1/2)T hl 0.9T; said
sipes
having a second, radially inner region of extent which
is formed so as to adjoin the first region of extent
inward in the radial direction R, said second region
extending to the sipe base over a height h2, measured
in the radial direction R, wherein, in the cross-
sectional planes perpendicular to the first main
direction of extent, the first, radially outer region
of extent of each sipe extends from the outside surface
to the second, radially inner region of extent, so as
to be aligned along a second main direction of extent
which has an angle of inclination a with respect to the
radial direction R, wherein 0 a 3 ,
characterized
in that, in the cross-sectional planes perpendicular to
the first main direction of extent, each sipe is
formedin the second, radially inner region of extent,
so as to extend to the sipe base in a curved manner
toward a side proceeding from the first, radially outer
region of extent, the two parallel sipe walls
comprising an outer sipe wall which delimits the sipe
towards an outside of the curvature in the second
region of extent, and an inner sipe wall which delimits
the sipe toward an inside of the curvature in the
second region of extent, wherein the outer sipe wall is
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delimited in a radially outward direction by a
transition point P, the transition point P deliming the
second region of extent with respect to the first
region of extent in the radially outward direction, and
the outer sipe wall is delimited at the sipe base by a
foot point Q, wherein a connecting path s between the
transition point P and the foot point Q in the cross-
sectional planes perpendicular to the first main
direction of extent extends with an angle of
inclination p with respect to the radial direction R,
where 15 p 45 .
The design of the sipe permits full utilization of the
advantages of the sipes with regard to the opening and
the closing action and with regard to the traction-
improving characteristics. The profile which is curved
to one side in the radially inner region of extent to
the sipe base results in a reduction of the stress in
the region of the radially inner region of extent of
the sipe, and a distribution of the stresses over the
entire arcuately curved profile proceeding from the
sipe base which is subject to the notch effect. The
sipe base, which as a result of the curvature is turned
out of the main direction of extent formed along the
radial extent of the sipe, furthermore permits a
reduction of the occurring notch effect. In this way,
the material-fatiguing loadings at the sipe base are
reduced, and the durability of the sipe and of the
profile element is increased.
Particularly advantageous for reducing the notch effect
is the design of a pneumatic vehicle tire, wherein the
sipe wall which delimits the sipe toward the outside of
the curvature in the second region of extent is formed
with a curvature profile with a curvature radius R1,
where 2 mm R1 10 mm,
about a curvature central
point M1 which lies on that side of the sipe which
points away from said sipe wall.
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Particularly advantageous is the design of a pneumatic
vehicle tire, wherein the sipe wall which delimits the
sipe toward the outside of the curvature is delimited
in the radially outward direction by a transition point
P, which delimits the second region of extent with
respect to the first region of extent in the radially
outward direction, and is delimited at the sipe base by
a foot point Q, wherein the connecting path s between
the transition point P and the foot point Q in the
section planes perpendicular to the first main
direction of extent runs with an angle of inclination p
with respect to the radial direction R, where 15 p
450, in particular 30 p 350. This
permits a
particularly great reduction in the notch effect, and
permits reliable removal from a mold.
Particularly advantageous is the design of a pneumatic
vehicle tire, wherein the sipe wall which delimits the
sipe toward the outside of the curvature is delimited
at the sipe base by a foot point Q, wherein the tangent
t to the curvature of the sipe wall at the foot point Q
runs at an angle of inclination y with respect to the
radial direction R, wherein 100 y 160 , in
particular 130 y 140 . This
permits a particularly
great reduction in the notch effect, and permits
reliable removal from a mold.
Particularly advantageous is the design of a pneumatic
vehicle tire, wherein the sipe is formed substantially
with a constant section width d over its radial extent
of height h2 in the second, radially inner region of
extent. This permits an improved force distribution in
the second, radially inner region of extent under load,
and thus a reduced notch effect.
Particularly advantageous is the design of a pneumatic
vehicle tire, wherein the two sipe walls which delimit
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the sipe are formed so as to be curved in the same
direction along their radial extent in the second
region of extent. This permits improved removability
from a mold while reducing the internal mobility of the
profile, as a result of which wear and rolling
resistance are improved, and the forces which cause the
notch effect are reduced.
Particularly advantageous is the design of a pneumatic
vehicle tire, wherein the two sipe walls which delimit
the sipe are formed so as to be curved in opposite
directions along their radial extent in the second
region of extent, wherein the sipe wall which delimits
the sipe in the direction of the curvature central
point of the sipe has a greater curvature radius R2
than the other sipe wall. This promotes easy insertion
into and removal from a mold, and permits an optimized
distribution of forces as the tire contact patch is run
through, as a result of which the notch effect is
reduced.
Particularly advantageous is the design of a pneumatic
vehicle tire, wherein the sipe, in the second, radially
inner direction of extent, is formed with a section
width which initially increases in the radially inward
direction along the radial extent of said sipe
proceeding from the radially outer point of extent P.
and which then decreases again toward the radially
inner point of extent Q. This promotes easy insertion
into and removal from a mold, and permits an optimized
distribution of forces as the tire contact patch is run
through, as a result of which the notch effect is
reduced.
Particularly advantageous is the design of a pneumatic
vehicle tire, wherein the sipe wall which inwardly
delimits the sipe in the direction of the axis of
curvature is delimited in the radially outward
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direction by a transition point P2 which delimits the
second region of extent with respect to the first
region of extent in the radially outward direction, and
is delimited at the sipe base by a foot point Q2, and
forms a rectilinear connection of the two points P2 and
Q2. This promotes easy insertion into and removal from
a mold, and permits an optimized distribution of forces
as the tire contact patch is run through, as a result
of which the notch effect is reduced.
Particularly advantageous is the design of a pneumatic
vehicle tire, wherein, in the section planes
perpendicular to the first main direction of extent,
the sipe is formed in the first region of extent with a
substantially constant section width along its radial
extent proceeding from the second region of extent
outward at least to a radial position at a distance h3
from the outside surface, wherein h3 (1/3)T.
Particularly advantageous is the design of a pneumatic
vehicle tire, wherein the sipe is formed with a section
width which increases continuously proceeding from the
radial position at a distance h3 from the outside
surface radially outward to the outside surface,
wherein the maximum section width B is formed at the
outside surface, where B < 0.5h3, wherein in particular
the thickening is formed toward that side of the sipe
which points away from the curvature of the second
region of extent. This promotes easy insertion into and
removal from a mold.
Particularly advantageous is the design of a pneumatic
vehicle tire, wherein the curvature of the sipe in the
second region of extent is oriented in the direction of
travel of the vehicle tire during forward travel. This
permits uniform compression of the sipe under load, and
a reduction of the forces acting at the sipe base.
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Particularly advantageous is the design of a pneumatic
vehicle tire, wherein the curvature of the sipe in the
second region of extent is orientated in the direction
of travel of the vehicle tire during reverse travel. In
this way, the forces acting in the sipe as the tire
contact patch is run through are distributed uniformly,
as a result of which the notch effect in the sipe base
can be reduced.
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The invention will be explained in more detail below on
the basis of the exemplary embodiments illustrated in
figures 1 to 4, in which:
figure 1 shows an axial partial section of a
circumferential portion of a tread profile of
a pneumatic vehicle tire in plan view,
figure 2 shows the tread profile of figure 1 in a
sectional illustration as per section II-II
in figure 1, for explaining the depth profile
of the sipes,
figure 3 shows a sipe as per the illustration of
figure 2, with an alternative design of the
depth profile of the sipe, and
figure 4 shows a sipe as per the illustration of
figure 2, with a further alternative design
of the depth profile of the sipe.
Figures 1 and 2 show a detail of a tread profile having
a plurality of radially elevated profile ribs 1, 2, 3
which are arranged adjacent to one another in the axial
direction A of the pneumatic vehicle tire and which
extend in each case over the entire circumference of
the pneumatic vehicle tire and which are spaced apart
from one another in the axial direction A of the
pneumatic vehicle tire by circumferential channels 4
and 5 which are aligned in the circumferential
direction U over the entire circumference of the
pneumatic vehicle tire.
For simplicity, figure 1 illustrates only the left-hand
side of a tread profile from the equatorial plane A to
the left-hand shoulder of the tire. The profile rib 1
is a shoulder profile rib, and the profile rib 3 is a
central profile rib. The central profile rib 3 and the
profile rib 2 are spaced apart axially from one another
by the circumferential channel 5. The profile rib 2 and
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the shoulder profile rib 1 are spaced apart axially
from one another by the circumferential channel 4. The
ground contact area extends in the axial direction over
its width TA into the left-hand profile rib 1. The
profile rib 2 is formed in a known way with parallel
sipes 7 which are arranged so as to be distributed over
the circumference of the pneumatic vehicle tire and
which extend from the circumferential channel 4 into
the circumferential channel 5 and which is formed in a
rectilinearly running manner in the outside surface 9,
which delimits the tire radially to the outside, of the
tire, wherein said sipes has an axial directional
component and a directional component oriented in the
circumferential direction, the greater of which is the
axial directional component.
Parallel sipes 8 are also formed, so as to be
distributed over the circumference of the pneumatic
vehicle tire, in the profile rib 3, which sipes extend
in the axial direction across the entire profile rib 3
proceeding from the circumferential channel 5, and
which sipes is formed in a rectilinearly running manner
in the outside surface 9, which delimits the tire
radially to the outside, of the tire, wherein said
sipes has an axial directional component and a
directional component oriented in the circumferential
direction, the greater of which is the axial
directional component. The shoulder profile block row 1
is formed with parallel sipes 6 which are arranged so
as to be distributed over the entire circumference of
the pneumatic vehicle tire and which extend outward in
the axial direction A from the circumferential channel
4 into the region of extent outside the ground contact
area TA and which are formed so as to extend in a
rectilinearly running manner in the axial direction A
in the outside surface 9 of the pneumatic vehicle tire.
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Figure 2, taking the sipes 6 of the profile rib 1 as an
example, shows the depth profile of the sipes 6. The
sipes 7 and 8 in the profile ribs 2 and 3 respectively
are formed with an analogous depth profile.
Here, figure 2 shows a section plane perpendicular to
the main direction of extent of the sipe 6 in the
outside surface 9. In the case of the sipes 6 which run
rectilinearly in the outside surface 9 and which are
aligned exclusively in the axial direction, said main
direction of extent in the outside surface 9 is
oriented in the axial direction A and the section plane
is therefore the section plane perpendicular to the
axial direction A.
As can be seen from figure 2, the sipe 6 is delimited
laterally by the two cut walls 10 and 11 which are of
corresponding form to one another. In the exemplary
embodiment illustrated in figure 2, the cut walls 10
and 11 extend at a constant distance d from one another
over the entire radial extent T of the sipe 6 from the
outside surface 9 to the sipe base 12, which distance
defines the section width.
The section width d is formed such that d < 0.6 mm,
preferably d = 0.5 mm.
The sipe 6, in a radially outer region of extent 16,
extends rectilinearly radially inward from the outside
surface 9 over a height of extent HD measured in the
radial direction R, so as to enclose an angle of
inclination a with the radial R, wherein a 30, and
defines the radial main extent 13 of the sipe. In the
exemplary embodiment illustrated, in said radially
outer region of extent 16, the sipe 6 extends with an
angle of inclination a = 00 with respect to the radial
R. The radial height of extent 1-11 is such that (1/2)T
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111 0.9T. In
the exemplary embodiment illustrated, 111 =
(2/3)T.
Adjoining the radially outer region of extent 16, the
sipe 6, in a radially inner region of extent 26,
extends inward in the radial direction R over a radial
height of extent h2 to the sipe base 12, wherein in the
radially inner region of extent 26, the two sipe walls
and 11 run in a curved fashion in circle segment
10 form about a curvature central point Ml. The curvature
central point Mi lies on that side of the sipe 6 in the
profile rib 1 which points away from the sipe wall 10.
Here, the sipe wall 10 extends from a transition point
P, which delimits the sipe wall 10 in the radially
inner region of extent 26 in the radially outward
direction with respect to the radially outer region of
extent 16, to the point Q which delimits the sipe wall
10 in the radially inward direction at the sipe base
12, and said sipe wall 10 runs in a curved fashion with
a radius R1 about the central point Mi. Here, the sipe
wall 11 extends from a transition point P2, which
delimits the sipe wall 11 in the radially inner region
of extent 26 in the radially outward direction with
respect to the radially outer region of extent 16, to
the point Q2 which delimits the sipe wall 11 in the
radially inward direction at the sipe base 12, and said
sipe wall 11 runs in a curved fashion with a radius
about the central point Ml. The curvature radius R1 of
the sipe wall 10 is greater than the curvature radius
of the sipe wall 11.
The curvature radius R1 is formed such that 2 mm R1
10 mm. In the exemplary embodiment illustrated, R1 = 9
mm.
The line of intersection s which connects the two
points P and Q which delimit the sipe wall 10 in the
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radially inner region of extent runs with an angle of
inclination p with respect to the radial R, where 15
p 45 . In the
exemplary embodiment illustrated, p is
selected such that 300 < p 35 . In the
specific
embodiment illustrated, p = 32 .
The tangent t to the curvature contour line of the
channel wall 10 at the point Q is at an angle of
inclination y with respect to the radial R, where 100
y 160 . In
particular exemplary embodiments, y is
selected such that 130 y 140 . In
the illustrated
exemplary embodiment, y is selected to be 135 .
In the illustrated exemplary embodiment, the curvature
central point M1 is arranged, as viewed in the
circumferential direction U of the pneumatic vehicle
tire, on that side of the main extent 13 of the sipe 6
in the radially outer region of extent 16 which is
arranged behind the sipe 6 when the pneumatic vehicle
tire rotates during forward travel of the pneumatic
vehicle tire. The curvature central point M1 thus lies
on that circumferential side which is situated on the
pneumatic vehicle tire in front of the main extent 13
of the sipe 6 in the radially outer region of extent 16
during reverse travel, and the curvature of the sipe in
the radially inner region of extent 26 is thus oriented
in the direction of travel of the vehicle tire during
reverse travel.
In another embodiment, the curvature central point M1
lies on that circumferential side which is situated on
the pneumatic vehicle tire in front of the main extent
13 of the sipe 6 in the radially outer region of extent
16 during forward travel, and the curvature of the sipe
in the radially inner region of extent 26 is thus
oriented in the direction of travel of the vehicle tire
during forward travel.
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Figure 3 shows a design of the sipe 6 in which the sipe
6, in the radially outer region of extent 16, runs in
an undulating or zig-zagged form along its main extent
13 from the outside surface 9 over the entire radial
height of extent hl. The rectilinear main extent 13 of
the sipe is the zero line of the undulating or zig-
zagged form, and is aligned at the angle of inclination
a with respect to the radial R. In this exemplary
embodiment, too, the section width d, formed by the
channel walls 10 and 11, of the sipe 6 is constant in
the radially outer region of extent 16.
Figure 3 shows a further exemplary embodiment of the
depth profile of the sipe, in which, in the radially
inner region of extent 26, the channel wall 10 runs in
a curved fashion about the curvature central point MI,
with a curvature radius RI, between the transition point
P and the point Q - as in the exemplary embodiment
illustrated in figure 2. In the exemplary embodiment
shown, however, the sipe wall 11 runs rectilinearly
between the points P2 and Q2, parallel to the straight
line s which connects the points P and Q. In the
radially inner region of extent 26 of the sipe 6, the
two channel walls 10 and 11 enclose a thickened opening
14 which forms a cavity and which, proceeding from the
transition point P of the channel wall 10, is formed
with a width d which initially increases in the
radially inward direction, and which subsequently, in
its radially inner region of extent, is formed with a
width d of the sipe which decreases continuously again
to the point Q which delimits the channel wall 10
radially to the inside.
Figure 4 shows a further exemplary embodiment of the
radially inner region of extent 26 of the sipe 6, in
which the channel wall 10 - as in the exemplary
embodiment of figure 2 - runs in a curved fashion about
the curvature central point MD with a curvature radius
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R1, between the two points P and Q which delimit the
channel wall 10 in the radially inner region of extent
26. In said embodiment, the channel wall 11 runs curved
in circle segment form about a curvature central point
M2, with a curvature radius R2, between the points P2
and Q2, wherein the curvature central point M2 is formed
on that side of the sipe 6 in the profile rib 1 which
points away from the sipe wall 11, and is thus formed
on the opposite side of the sipe 6 in the profile rib 1
from the curvature central point Ml. Here, the curvature
radius R2 is such that R2 > R1. It is thus the case in
this exemplary embodiment too that, in the radially
inner region of extent 26, the two sipe walls 10 and 11
enclose a thickening 14, which forms a cavity, of the
sipe 6, which thickening, proceeding from the
transition point P which delimits the sipe wall 10
radially toward the outside, has a width d of the sipe
which initially increases continuously in the radially
inward direction, and which subsequently, in the
radially inner region of extent of the radially inner
section of extent 26, has a width d of the sipe which
decreases continuously again to the point Q.
Figure 4 furthermore illustrates a further exemplary
embodiment of the radially outer region of extent 16 of
a sipe 6, in which, in the section planes perpendicular
to the first main direction of extent, the sipe 6 is
formed in the radially outer region of extent 16 with a
constant section width d along its radial extent
proceeding from the radially inner region of extent 26
outward to a radial position at a distance h3 from the
outside surface 9, where h3 (1/3)T.
Proceeding in the
radially outward direction from the radial position at
a distance h3 from the outside surface 9, the sipe 6 is
formed with a section width d which increases
continuously to the outside surface 9, wherein the
maximum section width B is formed at the outside
surface 9, where B < (1/2)h3. For this purpose, the sipe
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wall 10 is formed, in the radially outward direction
proceeding from the position at a distance h3 from the
outside surface 9, and in the circumferential direction
U which points away from the curvature central point Mu
such that its distance from the main extent 13 of the
sipe 6 in the radially outer region of extent 16
increases continuously. In the exemplary embodiment
illustrated, in the radial region of extent proceeding
from the position at a distance h3 from the outside
surface 9, the sipe wall 16 is curved about a curvature
central point which is formed on that circumferential
side of the sipe 6 which points away from the curvature
central point MI. In this way, in the region of extent
of the height h3, the sipe walls 10 and 11 enclose a
radially outwardly widening or thickening opening 15
which is arranged on that circumferential side of the
main extent 13 of the sipe which points away from the
curvature central point Ml. In another embodiment which
is not illustrated, the channel wall 10 is of
rectilinear form in the radial region of extent h3.
Even though the sipes 6, 7 and 8 are in each case of
rectilinear form in the outside surface 9 in figure 1,
it is provided in another embodiment (not illustrated)
that the sipes run in an undulating or zig-zagged form
in the outside surface 9, wherein the zero line of the
zig-zagged or undulating form in the outside surface 9
forms the main direction of extent of the sipe in the
outside surface 9.
The tread profile illustrated in figure 1 is a rib
profile with sipes. In another embodiment (not
illustrated), at least one of the circumferential ribs
is replaced by a profile block row which is formed from
profile block elements arranged in series in the
circumferential direction, which profile block elements
are spaced apart from one another in the
circumferential direction by transverse channels, and
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the sipes are formed in the profile block elements of
the profile block row.
In the exemplary embodiment illustrated, the tread
profile is a tread profile of a passenger motor vehicle
tire. In another embodiment, the tread profile is a
tread profile of a utility vehicle tire. In a further
alternative embodiment, the tread profile is a tread
profile of a van tire or of a tire for light
transporters.
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List of reference numerals
(Part of the description)
1 Profile rib
2 Profile rib
3 Profile rib
4 Circumferential channel
Circumferential channel
6 Sipe
7 Sipe
8 Sipe
9 Outside surface
Sipe wall
11 Sipe wall
12 Sipe base
13 Main extent
14 Thickened opening
Thickened opening
16 Outer region of extent
26 Inner region of extent
