CA3121369C

CA3121369C - Pneumatic vehicle tire

Info

Publication number: CA3121369C
Application number: CA3121369A
Authority: CA
Inventors: Jan Schlittenhard; Stefan Bosse; Eugen Henze
Original assignee: Continental Reifen Deutschland GmbH
Current assignee: Continental Reifen Deutschland GmbH
Priority date: 2018-12-06
Filing date: 2019-10-24
Publication date: 2023-09-19
Anticipated expiration: 2039-10-24
Also published as: DE102018221118A1; CA3121369A1; EP3890995B1; EP3890995A1; WO2020114673A1

Abstract

The invention relates to a pneumatic vehicle tire, comprising a tread having profile elements (1), for example tread lugs (1), which profile elements are separated from one another by grooves (2, 3) and are each provided with a plurality of sipes (4), which run at an angle of up to 45° to the axial direction and parallel to one another and have a constant width (B), a maximum sipe depth (T) and two sipe walls (5, 6). The sipes (4) are composed of a main portion (4a) reaching to the maximum sipe depth (T) or of such a main portion (4a) and at least one shallower edge portion (4b). In a top view of the sipe (4), the main portion (4a) comprises at least one shorter portion (4"a) and at least one portion (4'a) longer than the at least one shorter portion. The portions (4'a, 4"a) include an angle (a) of 90° to 140° with one another. In the longer portion (4'a), at least one recess (9) is formed in the one sipe wall (5), and a protrusion corresponding to the recess (9) lies opposite the recess on the other sipe wall (6). The protrusion (10) and the recess (9) are elongate in the direction of extent of the sipe (4). In the longer portion (4'a) or in each longer portion (4'a) of the main portion (4a), exactly one recess (9) which is mirror-symmetrical with respect to a cross-section center plane (E2) that is perpendicular to the sipe wall (5) and that runs in the radial direction and with respect to a longitudinal-section center plane (E1) that runs orthogonally to said cross-section center plane is formed in the one sipe wall (5). Any edge portions (4b) of the sipe (4) are free of protrusions (10) and recesses (9).

Description

Description Pneumatic vehicle tire [0001] The invention relates to a pneumatic vehicle tire comprising a tread with profile elements separated from one another by grooves, for example tread bars, which are respectively provided with a multiplicity of sipes extending at an angle of up to 450 to the axial direction and parallel to one another and having a constant width, a maximum sipe depth and two sipe walls, the sipes being formed from a main portion reaching to the maximum sipe depth or from such a main portion and at least one edge portion made more shallow, the main portion having in plan view of the sipe at least one shorter portion and at least one longer portion than this, the portions enclosing an angle of 90 to 140 with one another and at least one recess being formed on the one sipe wall in the longer portion, opposite which there is on the other sipe wall a projection corresponding to the recess, the projection and the recess being elongated in the direction of extent of the sipe.
[0001a] The invention also relates to a pneumatic vehicle tire comprising and tread with profile elements separated from one another by grooves respectively provided with a multiplicity of sipes extending at a sipe angle of up to 450 relative to an axial direction and parallel to one another and having a constant sipe width, a maximum sipe depth and two sipe walls, the sipes being formed from a main portion reaching to the maximum sipe depth, or from the main portion and at least one edge portion made more shallow, the main portion having, in plan view of the sipe, at least one shorter portion and at least one longer portion, the at least one shorter portion and the at least one longer portion enclosing an angle of 90 to 140 with one another and at least one recess being Date Regue/Date Received 2022-12-06 la formed on one of the two sipe walls in the longer portion, opposite which there is on the other one of the two sipe walls a projection corresponding to the recess, the projection and the recess being elongated in a direction of extent of the sipe, wherein, in the at least one longer portion of the main portion, there is formed exactly one recess on the corresponding one of the two sipe walls, the exactly one recess being formed mirror-symmetrically with respect to a cross-sectional center plane perpendicular to the corresponding one of the two sipe walls and running in a radial direction as well as with respect to a longitudinally sectional center plane orthogonal thereto, and wherein the at least one edge portion is free of projections and recesses.

[0002] Such a pneumatic vehicle tire is known for example from DE 10 2010 000 272 Al. According to a variant, the tread of this pneumatic vehicle tire has profile elements with sipes running in a stepped manner in plan view, which have a main portion formed to the sipe depth and two shallower edge portions. The main portion has shorter and longer portions, which alternate one after the other and enclose an angle of approximately 90 with one another. In the main portion, first projections, which have a flattened side that forms a supporting surface oriented to the radial direction, are formed in the longer portions in the radially outer region of the one sipe wall, the length of the projections being 1.5 mm to 3.0 mm and the width of the projections being 1.0 mm to 3.0 mm.
Date Regue/Date Received 2022-12-06

3 2 The supporting surfaces of the first projections should have a supporting effect when forces act in the transverse direction. Second projections, which have a flattened side that is oriented parallel to the tread periphery, are formed in the radially inner region of the sipe wall, the length of the projections being 3.0 mm to 7.0 mm and the width of the projections being 1.0 mm to 3.0 mm. The second projections limit the mobility of the profile elements in the circumferential direction as the tread wear progresses. The tread wear is intended to be evened out by such projections and associated corresponding recesses. Projections and corresponding recesses are provided both in the main portion and in the raised edge portions, which have a smaller depth.
[0003] Corresponding projections and recesses on sipe walls contribute to the rigidity of the profile elements and to improving certain driving properties of the tire, for example the traction properties on snow-covered roads. Since the sipes are very narrow (usual width 0.4 mm to 0.8 mm), the demolding behavior, i.e. the pulling out of the lamellae forming the sipes from the vulcanized tread, is especially problematic in the case of the previously known "three-dimensional" sipes provided with projections and recesses, so that there is the possibility of the sipes or the tread in the area of the sipes not being perfectly formed. In particular, tears or flaking of the tread rubber may occur in the area of the sipe edges.
Furthermore, it can happen that the projections formed "adhere"
to the corresponding indentations located on the lamella and are torn off from the sipe wall when the lamella is removed.

[0004] In the case of a pneumatic vehicle tire of the type mentioned at the beginning, which has a tread with sipes which in plan view have portions adjoining one another at an angle and therefore run in a zigzag shape, the problem explained with regard to demolding after vulcanization of the tire is exacerbated since zigzag-shaped lamellae - compared to Date Recue/Date Received 2021-05-28 straight lamellae - are in any case already more difficult to pull out of the sipe formed due to their geometry.

[0005] The invention is therefore based on the object of designing the sipes in the tread of a pneumatic vehicle tire of the type mentioned at the beginning in a way that avoids the formation of tears and flaking, the advantageous effects of correspondingly designed projections and recesses on the sipe walls, for example concerning the rigidity of the profile elements and the driving characteristics of the tire under winter driving conditions, should be maintained or even improved.

[0006] The stated object is achieved according to the invention by providing that, in the longer portion or in each longer portion of the main portion, on the one sipe wall there is formed exactly one recess, which is formed mirror-symmetrically with respect to a cross-sectional center plane perpendicular to the sipe wall and running in the radial direction as well as with respect to a longitudinally sectional center plane orthogonal thereto, and that any edge portions of the sipe are free of projections and recesses.

[0007] Sipes designed according to the invention therefore only have corresponding projections and recesses on the sipe walls in the main portion formed to the maximum sipe depth.
Due to their double-symmetrical shape, the projections and recesses are particularly stable. When demolding the lamellae forming these sipes in the vulcanization mold, significantly lower forces occur on the projections and recesses than in the known embodiments, so that no tears or flaking occur. In any provided edge portions of the sipes that are particularly critical with regard to the demolding behavior, the sipe walls are unstructured, that is to say free of projections and recesses. A tread with sipes with sipe walls designed in this Date Recue/Date Received 2021-05-28 way in its profile elements has a rigidity that is advantageous for the driving properties under winter driving conditions.

[0008] According to a preferred embodiment variant, the longitudinally sectional center plane of the recess runs at a depth, measured in the radial direction, of 30% to 50%, in particular of 35% to 45%, of the maximum sipe depth. This measure results in a mutual support of the sipe walls that is particularly advantageous for the tread stability.

[0009] In this context, it is also preferred if the recess has in the longitudinally sectional center plane a length which has 60% to 85%, in particular 75% to 80%, of a width measured in the longitudinally sectional center plane of a wall portion of the sipe wall which runs over the longer portion. The width of the wall portion should in this case be 4.0 mm to 7.0 mm.

[0010] According to a further preferred embodiment variant, the recess has along the cross-sectional center plane a width of 15% to 40%, in particular of 18% to 30%, of the maximum sipe depth. The width of the recess is thereby particularly advantageously matched to the depth of the sipe.

[0011] Support of the sipe walls that is particularly advantageous for the tread stability is additionally assisted by the fact that the recess has with respect to the level of the sipe wall a depth of 50% to 200%, in particular of 100% to 150%, of the sipe width.

[0012] According to a further preferred embodiment variant, the recess has, determined at the line of intersection between the longitudinally sectional center plane and the sipe wall, a distance of at least 0.5 mm respectively from the ends of the longer portion of the sipe. This measure is advantageous in particular for good demoldability of the recesses and corresponding projections.
Date Recue/Date Received 2021-05-28

[0013] In a further measure that is advantageous in this regard, the recess is delimited by a base which is U-shaped both in the cross section and in the longitudinal section of the recess.

[0014] In this context, it is additionally advantageous if the base of the recess is made up of a central base portion, which is rectangular when looking at the sipe wall, and two lateral base portions, which adjoin the longitudinal ends of the rectangular base portion and are rounded when looking at the sipe wall. As a result of this measure, the "edge regions"
of the recesses, which are sometimes somewhat more difficult to demold, and thus also the correspondingly shaped projections, can be demolded largely in a "stress-free" manner.

[0015] According to a further preferred embodiment variant, the main portion of the sipe runs in a zigzag shape in plan view, so that the main portion is made up of a plurality of shorter and longer portions, with a longer portion alternately following a shorter portion. Sipes of such a design are particularly favorable for the driving properties under winter driving conditions.

[0016] It is additionally advantageous if the angle which the longer portion or the longer portions of the main portion enclose with the shorter portion or shorter portions in plan view is 1000 to 140 , in particular 115 to 125 .

[0017] According to a further preferred embodiment variant, the longer portion or the longer portions runs or run at an angle of 0 to 25 to the axial direction.

[0018] Another preferred embodiment variant is characterized in that all of the shorter portions of the main portion run parallel to one another and in that all of the longer portions of the main portion run parallel to one another.
Date Recue/Date Received 2021-05-28

[0019] In particular, the main portion has up to four longer portions.

[0020] Further features, advantages and details of the invention will now be described in more detail with reference to the drawing, which schematically shows an exemplary embodiment of the invention. In the figures:
Fig. 1 shows a view of tread bars of a tread of a pneumatic vehicle tire, Fig. 2 shows a plan view of a sipe with an embodiment variant of the invention, Fig. 3 shows a section along the line III-III of Fig. 2, Fig. 4 shows a tread bar opened or cut open along a sipe according to the viewing direction indicated in Fig. 2 by the arrow S, Fig. 5 shows a section along the line V-V of Fig. 4.

[0021] The invention is concerned with the configuration of sipes in treads of pneumatic vehicle tires of a radial design, in particular for passenger cars, vans or light trucks, the pneumatic vehicle tires being particularly well suited for driving under winter driving conditions.

[0022] Fig. 1 shows four tread bars 1, which belong to two rows of bars running next to one another in the middle tread area, which are separated from one another by a circumferential groove 2 running straight in the exemplary embodiment shown, further circumferential grooves, not designated, delimiting the rows of bars on the outside. The double arrow U indicates the circumferential direction of the tire.

[0023] The circumferential groove 2 has in the radial direction the tread depth intended for the respective pneumatic vehicle tire, which is in particular 6.5 mm to 10.0 mm. Within the rows of bars, tread bars 1 that are adjacent in the circumferential direction are respectively separated from one Date Recue/Date Received 2021-05-28 another by a transverse groove 3, which in the exemplary embodiment shown has a depth that corresponds to the circumferential groove 2.

[0024] Each tread bar 1 is provided with two correspondingly designed sipes 4, which are evenly distributed within each tread bar 1, extend parallel to one another and in the transverse direction and traverse the respective tread bar 1.
The further configuration of the sipes 4 is explained below with reference to an individual sipe 4.

[0025] As Fig. 3 shows, the sipe 4 has a constant sipe width B of in particular 0.4 mm to 0.8 mm, in the radial direction a maximum sipe depth T of 80% to 100% of the profile depth, two opposite sipe walls 5, 6 and two sipe base portions 7 (Fig.
4) running at the sipe depth T.

[0026] According to Fig. 2, the sipe 4 is made up of a main portion 4a which is zigzag-shaped, in particular sawtooth-shaped, in plan view and at least over the majority of its extent is formed to the sipe depth T, and two lateral edge portions 4b raised in a known manner (also see Fig. 4). The main portion 4a is formed from a number of longer portions 4a', which are aligned parallel to one another in plan view, and a number of shorter portions 4a" than the longer portions 4a', which are aligned parallel to one another, with a portion 4a' respectively following a portion 4a" in an alternating manner. The portions 4a' and 4a" respectively enclose with one another in plan view an angle a of 90 to 1400, in particular of at least 100 , and particularly preferably of 115 to 125 , the longer portions 4a' running at an angle a' of preferably 0 to 25 to the axial direction. The main portion 4a has a length of extent li (Fig. 4), which is at least 80% of the length of extent of the sipe 4.
Date Recue/Date Received 2021-05-28

[0027] As Fig. 4 shows, in the exemplary embodiment shown, a base elevation 8 which locally reduces the depth of the main portion 4a, connects the sipe walls 5, 6 to one another and separates the already mentioned sipe base portions 7 from one another, is formed in the center of the main portion 4a. In the area of the base elevation 8, the main portion 4a has at its shallowest point in the radial direction a depth of for example 30% to 75%, in particular of 50% to 65%, of the sipe depth T.

[0028] According to Fig. 5, the sipe wall 5 has planar wall portions 5a' delimiting the longer portions 4a' of the main portion 4a and planar wall portions 5a" delimiting the shorter portions 4a" of the main portion 4a. The sipe wall 6 has wall portions opposite the wall portions 5a', 5a" and aligned parallel thereto. The wall portions 5a', 5a" and the opposing wall portions of the sipe wall 6 are elongated in the radial direction, are essentially rectangular and extend to the sipe depth T (Fig. 4). In each wall portion 5a' there is exactly one recess 9 (Figs. 3 to 5), opposite which there is a corresponding projection 10 (Fig. 3) formed on the respective wall portion of the sipe wall 6. The sipe wall 6 is therefore designed at least essentially as a positive of the sipe wall (see Fig. 3).

[0029] As Fig. 4 shows, when looking at the wall portion 5a', the recess 9 is formed as elongated in the direction of extent of the sipe 4 and furthermore with respect to a longitudinally sectional center plane El perpendicular to the wall portion 5a' and running in the horizontal direction (coincides with the section line V-V) and symmetrical with respect to a cross-sectional center plane E2 which is perpendicular to the wall portion 5a' and runs in the radial direction. The longitudinally sectional center plane El runs at a depth -Li, determined in the radial direction, of 30% to 50%, in particular of 35% to 45%, of the sipe depth T. The recess 9 Date Recue/Date Received 2021-05-28 has along the longitudinally sectional center plane El a length lv (Fig. 5) of 60% to 85%, in particular 75% to 80%, of the width bl measured in the longitudinally sectional center plane El (Fig. 5) of the wall portion 5a', the width bl being in particular 4.0 mm to 7.0 mm. The length lv of the recess 9 and the width bi of the wall portion 5a' are preferably matched to one another in such a way that the recess 9, determined at the line of the intersection between the longitudinally sectional center plane El and the wall portion 5a', is respectively at a distance al from the ends of the longer portion 4a' of at least 0.5 mm (see Fig. 4 in combination with Fig. 5). Furthermore, the recess 9 has along the cross-sectional center plane E2 a width by (Fig. 5) of 15% to 40%, in particular of 18% to 30%, of the sipe depth T.

[0030] The recess 9 is delimited by a slightly U-shaped base 11 (Fig. 3, Fig. 5) viewed in cross section and in the longitudinal section of the recess 9 and has a depth tv with respect to the level of the wall portion 5a' (Fig. 3, Fig. 5) of 50% to 200%, in particular of 100% to 150%, of the sipe width B (Fig. 3). As Fig. 4 shows, the base 11 is made up of a central base portion 11a, which is rectangular when looking at the wall portion 5a', and two lateral base portions 11b, which are rounded on the outside when looking at the wall portion 5a', the central base portion ha running over the majority, in particular over at least 65%, of the length lv mentioned of the recess 9.

[0031] The invention is not limited to the embodiment variants described.

[0032] The edge portions of the sipes are optional. The sipes can therefore have no, one or two edge portion(s). In the case of sipes without an edge portion, the sipe is formed by the main portion. Furthermore, the sipes may extend at an angle of 00 to 450 to the axial direction and also be provided in other Date Recue/Date Received 2021-05-28 profile elements, such as for example profile strips or the like. Within a profile element, the sipes run parallel to one another in a known manner, at least in groups. The sipes may end with one or both ends within the respective profile element. Furthermore, the recesses may have a shape that deviates from the shape described. The base elevation in the sipe is optional.
Date Recue/Date Received 2021-05-28 List of designations 1 .......... Tread bar 2 .......... Circumferential groove 3 .......... Transverse groove 4 .......... Sipe 4a ......... Main portion 4a' ....... Portion 4a" ....... Portion 4b ......... Edge portion .......... Sipe wall 5a' ....... Wall portion 5a" ....... Wall portion 6 .......... Sipe wall 7 .......... Sipe base portion 8 .......... Base elevation 9 .......... Recess ........ Projection 11 ......... Base ha ......... Central base portion lib ........ Lateral base portion al ........ Distance 131 ....... Width B .......... Sipe width El ........ Longitudinal center plane E2 ........ Cross-sectional center plane 11 ........ Length of extent lv ........ Length t1 ........ Depth tv ........ Depth T .......... Maximum sipe depth U .......... Double arrow (circumferential direction) a, a' ..... Angle Date Recue/Date Received 2021-05-28

Claims

Patent claims

1. A pneumatic vehicle tire, comprising:
a tread with profile elements separated from one another by grooves respectively provided with a multiplicity of sipes extending at a sipe angle of up to 45 relative to an axial direction and parallel to one another and having a constant sipe width, a maximum sipe depth and two sipe walls, the sipes being formed from a main portion reaching to the maximum sipe depth, or from the main portion and at least one edge portion made more shallow, the main portion having, in plan view of the sipe, at least one shorter portion and at least one longer portion, the at least one shorter portion and the at least one longer portion enclosing an angle of 90 to 140 with one another and at least one recess being formed on one of the two sipe walls in the longer portion, opposite which there is on the other one of the two sipe walls a projection corresponding to the recess, the projection and the recess being elongated in a direction of extent of the sipe, wherein, in the at least one longer portion of the main portion, there is formed exactly one recess on the corresponding one of the two sipe walls, the exactly one recess being formed mirror-symmetrically with respect to a cross-sectional center plane perpendicular to the corresponding one of the two sipe walls and running in a radial direction as well as with respect to a longitudinally sectional center plane orthogonal thereto, and wherein the at least one edge portion is free of projections and recesses.

2. The pneumatic vehicle tire as claimed in claim 1, characterized in that the profile elements of the tread comprise tread bars.

3. The pneumatic vehicle tire as claimed in claim 1 or 2, characterized in that the longitudinally sectional center plane of the recess runs at a depth, measured in the radial direction, of 30% to 50% of the maximum sipe depth.
Date Recue/Date Received 2022-12-06

4. The pneumatic vehicle tire as claimed in claim 1 or 2, characterized in that the longitudinally sectional center plane of the recess runs at a depth of 35% to 45% of the maximum sipe depth.

5. The pneumatic vehicle tire as claimed in any one of claims 1 to 4, characterized in that the recess has, in the longitudinally sectional center plane (El), a length which corresponds to 60% to 85% of a wall portion width (bi) measured in the longitudinally sectional center plane of a wall portion of the corresponding one of the two sipe walls which runs over the at least one longer portion.

6. The pneumatic vehicle tire as claimed in claim 5, characterized in that the length corresponds to 75% to 80% of the wall portion width.

7. The pneumatic vehicle tire as claimed in claim 5 or 6, characterized in that the wall portion width is 4.0 mm to 7.0 mm.

8. The pneumatic vehicle tire as claimed in any one of claims 1 to 7, characterized in that the recess has, along the cross-sectional center plane, a recess width corresponding to 15% to 40% of the maximum sipe depth.

9. The pneumatic vehicle tire as claimed in claim 8, characterized in that the recess width corresponds to 18% to 30% of the maximum sipe depth.

10. The pneumatic vehicle tire as claimed in any one of claims 1 to 9, characterized in that the recess has, with respect to a level of the corresponding one of the two sipe walls, a recess depth corresponding to 50% to 200% of the sipe width.

11. The pneumatic vehicle tire as claimed in claim 10, characterized in that the recess depth corresponds to 100% to 150% of the supe width.

12. The pneumatic vehicle tire as claimed in any one of claims 1 to 11, characterized in that the recess has, determined at a line of intersection between the longitudinally sectional center plane and the corresponding one of the two sipe walls, a distance of at least 0.5 mm respectively from each end of the at least one longer portion.
Date Recue/Date Received 2022-12-06

13. The pneumatic vehicle tire as claimed in any one of claims 1 to 12, characterized in that the recess is delimited by a base which is U-shaped both in cross section and longitudinal section of the recess.

14. The pneumatic vehicle tire as claimed in claim 13, characterized in that the base of the recess is made up of a central base portion having longitudinal ends, and which is rectangular when looking at the corresponding one of the two sipe walls, and two lateral base portions, which adjoin the longitudinal ends of the base portion, the lateral base portions being rounded when looking at the corresponding one of the two sipe walls.

15. The pneumatic vehicle tire as claimed in any one of claims 1 to 14, characterized in that the main portion comprises a plurality of shorter and longer portions, with the plurality of shorter and longer portions alternating each other along the main portion, and wherein the main portion runs in a zigzag shape in plan view.

16. The pneumatic vehicle tire as claimed in any one of claims 1 to 15, characterized in that the angle enclosed between the longer and shorter portions is 1000 to 140 .

17. The pneumatic vehicle tire as claimed in claim 16, characterized in that the angle is 115 to 125 .

18. The pneumatic vehicle tire as claimed in any one of claims 1 to 17, characterized in that the at least one longer portion runs at a second angle of 0 to 25 relative to the axial direction.

19. The pneumatic vehicle tire as claimed in any one of claims 1 to 18, characterized in that all of the shorter portions of the main portion run parallel to one another, and in that all of the longer portions of the main portion run parallel to one another.

20. The pneumatic vehicle tire as claimed in any one of claims 1 to 19, characterized in that the main portion has up to four longer portions.
Date Recue/Date Received 2022-12-06