WO2019123561A1 - A tread with sipe for multi performance - Google Patents

A tread with sipe for multi performance Download PDF

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Publication number
WO2019123561A1
WO2019123561A1 PCT/JP2017/045690 JP2017045690W WO2019123561A1 WO 2019123561 A1 WO2019123561 A1 WO 2019123561A1 JP 2017045690 W JP2017045690 W JP 2017045690W WO 2019123561 A1 WO2019123561 A1 WO 2019123561A1
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WO
WIPO (PCT)
Prior art keywords
incision
protrusion
tread
face
equal
Prior art date
Application number
PCT/JP2017/045690
Other languages
French (fr)
Inventor
Masayoshi Nomura
Kazutaka YOKOKAWA
Original Assignee
Compagnie Generale Des Etablissements Michelin
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Filing date
Publication date
Application filed by Compagnie Generale Des Etablissements Michelin filed Critical Compagnie Generale Des Etablissements Michelin
Priority to PCT/JP2017/045690 priority Critical patent/WO2019123561A1/en
Publication of WO2019123561A1 publication Critical patent/WO2019123561A1/en

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
    • B60C11/00—Tyre tread bands; Tread patterns; Anti-skid inserts
    • B60C11/03—Tread patterns
    • B60C11/12—Tread patterns characterised by the use of narrow slits or incisions, e.g. sipes
    • B60C11/1204—Tread patterns characterised by the use of narrow slits or incisions, e.g. sipes with special shape of the sipe
    • B60C11/1218—Three-dimensional shape with regard to depth and extending direction
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
    • B60C11/00—Tyre tread bands; Tread patterns; Anti-skid inserts
    • B60C11/03—Tread patterns
    • B60C11/12—Tread patterns characterised by the use of narrow slits or incisions, e.g. sipes
    • B60C11/1272—Width of the sipe
    • B60C11/1281—Width of the sipe different within the same sipe, i.e. enlarged width portion at sipe bottom or along its length
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
    • B60C11/00—Tyre tread bands; Tread patterns; Anti-skid inserts
    • B60C11/03—Tread patterns
    • B60C11/0306—Patterns comprising block rows or discontinuous ribs
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
    • B60C11/00—Tyre tread bands; Tread patterns; Anti-skid inserts
    • B60C11/03—Tread patterns
    • B60C11/12—Tread patterns characterised by the use of narrow slits or incisions, e.g. sipes
    • B60C11/1259—Depth of the sipe
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
    • B60C11/00—Tyre tread bands; Tread patterns; Anti-skid inserts
    • B60C11/03—Tread patterns
    • B60C11/12—Tread patterns characterised by the use of narrow slits or incisions, e.g. sipes
    • B60C11/1204—Tread patterns characterised by the use of narrow slits or incisions, e.g. sipes with special shape of the sipe
    • B60C2011/1209—Tread patterns characterised by the use of narrow slits or incisions, e.g. sipes with special shape of the sipe straight at the tread surface

Definitions

  • the present invention relates to a tread for a tire, in particular to a tread for a tire provided with an incision for improving wintry performance from brand new to middle worn state and wet performance at close to end of life.
  • the “studless” and/or “winter” tire is often provided with a wear indication means for wintry usage (a winter indication means) in a tread groove, so-called “platform”, “snow wear bar” and/or “snow platform”, which indicates that remaining tread depth becomes less effective for driving on wintry (or white) road.
  • a wear indication means for wintry usage a winter indication means
  • platform so-called “snow wear bar” and/or “snow platform”
  • the tire can be used for driving on normal (or black) road until reaching to a legal tread wear indicator, thus there is a desire to increase performance on wintry (or white) road until the winter indication means, and to increase performance on normal (or black) road after the winter indication means.
  • the “studless” and/or “winter” tire is often provided with two or more radially laminated different rubber layers, an outer rubber layer is designed for better wintry (or white) road performance, an inner rubber layer is designed for better normal (or black) road performance.
  • an outer rubber layer is designed for better wintry (or white) road performance
  • an inner rubber layer is designed for better normal (or black) road performance.
  • WO2009/077499 discloses a tread for a tire provided with an incision having a wide portion and a narrow portion alternately, and the wide portion extending radially toward depth direction.
  • WO2015/086622 discloses a tread for a tire provided with a cut out (an incision) comprising an internal part having a shape of a channel and an intermediate part is making a connection between the internal part and an external part.
  • WO2012/041876 discloses a tread for a tire provided with an incision having at least one protuberance in order to reduce a width of the incision.
  • a “radial direction/orientation” is a direction/orientation perpendicular to axis of rotation of the tire. This direction/orientation corresponds to thickness orientation of the tread.
  • An “axial direction/orientation” is a direction/orientation parallel to axis of rotation of the tire.
  • a “circumferential direction/orientation” is a direction/orientation which is tangential to any circle centered on axis of rotation. This direction/orientation is perpendicular to both the axial direction/orientation and the radial direction/orientation.
  • a “tire” means all types of elastic tire whether or not subjected to an internal pressure.
  • a “tread” of a tire means a quantity of rubber material bounded by lateral surfaces and by two main surfaces one of which is intended to come into contact with ground when the tire is rolling.
  • a “groove” is a space between two rubber faces/sidewalls which do not contact between themselves under usual rolling condition connected by another rubber face/ bottom.
  • a groove has a width and a depth.
  • a “sipe”, also referred to as an “incision”, is a narrow cutout formed toward radially inwardly from a surface of a tread made by, for example a thin blade having a shape like a knife blade.
  • a width of the incision at the surface of the tread is narrower than a groove, for example less than or equal to 3.0mm. This incision may, different from the groove, be partly or completely closed when such the incision is in a contact patch and under usual rolling condition.
  • the present invention provides a tread for a tire having a contact face intended to come into contact with ground during rolling, the tread being provided with a plurality of grooves of a depth D opening to the contact face and a plurality of contact elements being delimited by the plurality of grooves, each the plurality of contact elements having a top face constituting a part of the contact face and at least one incision of a depth d opening to the top face and extending radially inward of the contact elements, the at least one incision being delimited via two opposed incision faces being distant with a distance t measured on the top face of the contact element when the tread being brand new, the at least one incision being provided with at least two protrusions extending from at least one of the two opposed incision faces towards another opposed incision faces, a protrusion amount p of the protrusion being at least equal to 51% of the distance t between the two opposed incision faces measured on a plane parallel to the top face, the at least two protrusions having no overlap on plan view of the contact element
  • This arrangement provides improvement of wintry (or white) road performance until the winter indication means while still improving level of normal (or black) road performance after the winter indication means.
  • the protrusion amount p of the protrusion being at least equal to 51% of the distance t between the two opposed incision faces measured on the plane parallel to the top face, the protrusion would contact with another opposed incision face with loading resulting an increase of stiffness of the contact element for better use of the top face (the contact face) in contact with wintry ground. Therefore it is possible to improve wintry (or white) road performance until the winter indication means.
  • protrusion amount p of the protrusion is less than 51% of the distance t between the two opposed incision faces, there is a risk that the protrusion would not contact with another opposed incision face with loading, or contact occurs only with excessive deformation, which leads degradation of wintry (or white) road performance until the winter indication means.
  • this protrusion amount p of the protrusion at least equal to 51% of the distance t between the two opposed incision faces measured on the plane parallel to the top face, it is possible to improve wintry (or white) road performance until the winter indication means.
  • the bottom edge of the protrusion connecting with the incision face locates at least equal to 55% of the depth D of the groove from the top face when the tread being brand new and the top edge of the protrusion connecting with the incision face and radially outward of the bottom edge of the protrusion locates at most equal to 30% of the depth D of the groove from the top face when the tread being brand new, the protrusion contributes to increase an area of the top face (the contact face) to be in contact with wintry ground while increasing a length of an edge of the incision when remaining tread depth is reached to a level of the protrusion. Therefore it is possible to improve further wintry (or white) road performance until the winter indication means.
  • the incision When remaining tread depth is reached to a level of the bottom edge of the protrusion, the incision increases its width (distance t between two opposed incision faces) for better evacuation of water. Therefore it is possible to improve normal (or black) road performance after the winter indication means.
  • the bottom edge of the protrusion connecting with the incision face locates less than 55% of the depth D of the groove from the top face when the tread being brand new, there is a risk that the protrusion disappears before reaching to the winter indication means thus wintry (or white) road performance until the winter indication means cannot be improved.
  • this bottom edge of the protrusion connecting with the incision face being located at least equal to 55% of the depth D of the groove from the top face when the tread being brand new, it is possible to improve wintry (or white) road performance until the winter indication means.
  • This bottom edge of the protrusion connecting with the incision face is preferably located at least equal to 60% of the depth D of the groove from the top face when the tread being brand new, more preferably at least equal to 65% and at most equal to 80% of the depth D of the groove from the top face when the tread being brand new.
  • top edge of the protrusion connecting with the incision face locates more than 30% of the depth D of the groove from the top face when the tread being brand new, there is a risk that the protrusion cannot contribute increase of stiffness of the contact element even the protrusion is in contact with another opposed incision face, or cannot contribute increase of the length of the edge of the incision thus wintry (or white) road performance until the winter indication means cannot be improved.
  • this top edge of the protrusion connecting with the incision face and radially outward of the bottom edge of the protrusion being located at most equal to 30% of the depth D of the groove from the top face when the tread being brand new, it is possible to improve wintry (or white) road performance until the winter indication means.
  • This top edge of the protrusion connecting with the incision face is preferably located at most equal to 25% of the depth D of the groove from the top face when the tread being brand new, still more preferably at most equal to 20% of the depth D of the groove from the top face when the tread being brand new.
  • the protrusions in the same incision adjacent in an extending direction of the incision are protruding from different incision faces.
  • the top edge of the protrusion is radially inwardly offset from the top face of the contact element.
  • the top edge of the protrusion is at most equal to 1.5 mm radially inwardly offset from the top face of the contact element.
  • this offset is more than 1.5 mm, there is a risk that the protrusion cannot contribute increase of stiffness of the contact element even the protrusion is in contact with another opposed incision face, or cannot contribute increase of the length of the edge of the incision thus wintry (or white) road performance until the winter indication means cannot be improved.
  • this offset at most equal to 1.5 mm radially inwardly from the top face of the contact element, it is possible to improve wintry (or white) road performance until the winter indication means.
  • the distance t between the two opposed incision faces is between 0.8 mm and 3.0 mm.
  • this distance t between the two opposed incision faces is less than 0.8 mm, there is a risk that increase of the distance t between the two opposed incision faces when remaining tread depth is reached to the level of the bottom edge of the protrusion is insufficient for evacuating water thus degradation of normal (or black) road performance after the winter indication means. If this distance t between the two opposed incision faces is more than 3.0 mm, there is a risk that manufacturing of the incision provided with the protrusions and the tread having the incision becomes inefficient thus degradation of productivity. By setting this distance t between the two opposed incision faces between 0.8 mm and 3.0 mm, it is possible to improve normal (or black) road performance after the winter indication means while maintaining productivity of the incision provided with the protrusions and the tread having the incision.
  • This distance t between the two opposed incision faces is preferably between 0.8 mm and 2.5 mm, more preferably between 0.8 mm and 2.0 mm and still more preferably between 1.0 mm and 2.0 mm.
  • the protrusion amount p of the protrusion is at least equal to 60% of the distance t between the two opposed incision faces, and the protrusion amount p of the protrusion is at least equal to 0.1 mm smaller than the distance t between the two opposed incision faces.
  • this protrusion amount p of the protrusion is less than 60% of the distance t between the two opposed incision faces, there is a risk that the protrusion would not contact with another opposed incision face with loading, or contact occurs only with excessive deformation, which leads degradation of wintry (or white) road performance until the winter indication means. If this protrusion amount p of the protrusion is less than 0.1 mm smaller than the distance t between the two opposed incision faces, there is a risk that manufacturing of the incision provided with the protrusions and the tread having the incision becomes inefficient thus degradation of productivity.
  • this protrusion amount p of the protrusion is at least equal to 60% of the distance t between the two opposed incision faces and the protrusion amount p of the protrusion is at least equal to 0.1 mm smaller than the distance t between the two opposed incision faces, it is possible to improve wintry (or white) road performance until the winter indication means while maintaining productivity of the incision provided with the protrusions and the tread having the incision.
  • This protrusion amount p of the protrusion is preferably at least equal to 65% of the distance t between the two opposed incision faces, more preferably at least equal to 70% of the distance t between the two opposed incision faces and still more preferably at least equal to 80% of the distance t between the two opposed incision faces. And this protrusion amount p of the protrusion is preferably at least equal to 0.2 mm smaller than the distance t between the two opposed incision faces, more preferably at least equal to 0.5 mm smaller than the distance t between the two opposed incision faces and still more preferably at least equal to 0.8 mm smaller than the distance t between the two opposed incision faces.
  • the bottom edge of the protrusion locates at least equal to 3.0 mm smaller than the depth D of the groove from the top face.
  • this bottom edge of the protrusion locates less than 3.0 mm smaller than the depth D of the groove from the top face, there is a risk that improvement of normal (or black) road performance is provided too late after the winter indication means.
  • this bottom edge of the protrusion being located at least equal to 3.0 mm smaller than the depth D of the groove from the top face, it is possible to provide improvement of normal (or black) road performance at appropriate timing after the winter indication means.
  • This bottom edge of the protrusion locates preferably at least equal to 3.2 mm smaller than the depth D of the groove from the top face, more preferably at least equal to 3.5 mm smaller than the depth D of the groove from the top face.
  • a tread for a tire provided with at least one incision such the tread can provide improvement of wintry (or white) road performance until the winter indication means while still improving level of normal (or black) road performance after the winter indication means.
  • Fig. 1 is a schematic perspective view of a portion of a tread for a tire according to a first embodiment of the present invention
  • Fig. 2 is a schematic plan view of a portion of a tread for a tire according to the first embodiment of the present invention
  • Fig. 3 is a schematic cross sectional view taken along line III-III in Fig. 2
  • Fig. 4 is a schematic plan view of a portion of a tread for a tire worn out below winter indication means according to the first embodiment of the present invention
  • Fig. 5 is a schematic plan view of a portion of a tread for a tire according to a second embodiment of the present invention
  • Fig. 6 is a schematic cross sectional view taken along line VI-VI in Fig. 5;
  • a tread 1 for a tire according to a first embodiment of the present invention will be described referring to Figs. 1, 2, 3 and 4.
  • Fig. 1 is a schematic perspective view of a portion of a tread for a tire according to a first embodiment of the present invention.
  • Fig. 2 is a schematic plan view of a portion of a tread for a tire according to the first embodiment of the present invention.
  • Fig. 3 is a schematic cross sectional view taken along line III-III in Fig. 2.
  • Fig. 4 is a schematic plan view of a portion of a tread for a tire worn out below winter indication means according to the first embodiment of the present invention.
  • the tread 1 is a tread for a tire having dimension 225/45R17 and comprises a contact face 2 intended to come into contact with the ground during rolling, and a plurality of grooves 3 of a depth D (shown in Fig. 3) opening to the contact face 2.
  • the plurality of grooves 3 include circumferential grooves 3a extending generally in circumferential orientation (as indicated in Fig. 2) and lateral grooves 3b extending generally in axial orientation (as indicated in Fig. 2).
  • the plurality of grooves 3 (the circumferential grooves 3a and the lateral grooves 3b) are delimiting a plurality of contact elements 4.
  • Each the plurality of contact elements 4 having a top face 41 constituting a part of the contact face 2.
  • the contact elements 4 also comprise at least one incision 5 of a depth d (shown in Fig. 3) opening to the top face 41 and extending radially inward of the contact elements 4.
  • the at least one incision 5 being delimited via two opposed incision faces 51, 52 distant with a distance t (shown in Fig. 2) measured on the top face 41 of the contact element 4 when the tread 1 being brand new.
  • the at least one incision (two incisions) 5 being provided with at least two protrusions 53 extending from at least one of the two opposed incision faces 51 (or 52) towards another opposed incision faces 52 (or 51) as to protruding circumferentially inward to a middle of the contact element 4.
  • a protrusion amount p of the protrusion 53 being at least equal to 51% of the distance t between the two opposed incision faces 51, 52 measured on a plane parallel to the top face 41, the at least two protrusions 53 having no overlap on plan view of the contact element 4 but having an overlap on cut view of the contact element 4 (shown in Fig. 3).
  • the protrusions 53 have a trapezoid shape in plan view of the contact element 4, two protrusions 53 in the same incision 5 are offset each other in axial orientation, axial ends of the protrusions 53 on the incision face 51 (or 52) are both offset from the groove 3 (circumferential groove 3a).
  • two protrusions 53 are provided on one incision face 51 (or 52), the distance t between the two opposed incision faces 51, 52 is 1.0 mm thus between 0.8 mm and 3.0 mm, the protrusion amount p of the protrusion 52 is 0.7 mm, thus at least equal to 60% of the distance t between the two opposed incision faces 51, 52, and is at least equal to 0.1 mm smaller than the distance t between the two opposed incision faces 51, 52.
  • the protrusion 53 provided with the incision 5 extending from one of the incision face 51 (or 52) toward another incision face 52 (or 51) has a right trapezoid shape in a cross sectional view.
  • a radially external part of the protrusion 53 is substantially parallel to the top face 41 of the contact element 4, a radially internal part of the protrusion 53 is extending upwardly from one of the incision face 51 (or 52) toward another incision face 52 (or 51).
  • a bottom edge 54 of the protrusion 53 connecting with the incision face 51 (or 52) locates at least equal to 55% of the depth D of the groove 3 from the top face 41 when the tread 1 being brand new and at least equal to 3.0 mm smaller than the depth D of the groove 3 from the top face 41, and a top edge 55 of the protrusion 53 connecting with the incision face 51 (or 52) radially outward of the bottom edge 54 of the protrusion 53 is radially inwardly offset from the top face 41 of the contact element 4, the top edge 55 of the protrusion 53 locates at most equal to 30% of the depth D of the groove 3 from the top face 41 when the tread 1 being brand new.
  • the depth D of the groove 3 is 8.0 mm
  • the depth d of the incision 5 is 7.0 mm
  • the bottom edge 55 of the protrusion 53 locates 2.4 mm smaller than the depth D of the groove 3 thus 70% of the depth D
  • the top edge 55 of the protrusion 53 is 1.0 mm offset from the top face 41 thus at most equal to 1.5 mm radially inwardly offset from the top face 41 of the contact element 4.
  • the protrusion amount p of the protrusion 53 being at least equal to 51% of the distance t between the two opposed incision faces 51, 52 measured on the plane parallel to the top face 41, the protrusion 53 would contact with another opposed incision face 52 (or 51) with loading resulting an increase of stiffness of the contact element 4 for better use of the top face 41 (the contact face 2) in contact with wintry ground. Therefore it is possible to improve wintry (or white) road performance until the winter indication means.
  • protrusion amount p of the protrusion 53 is less than 51% of the distance t between the two opposed incision faces 51, 52, there is a risk that the protrusion 53 would not contact with another opposed incision face 52 (or 51) with loading, or contact occurs only with excessive deformation, which leads degradation of wintry (or white) road performance until the winter indication means.
  • this protrusion amount p of the protrusion 53 is at least equal to 51% of the distance t between the two opposed incision faces 51, 52 measured on the plane parallel to the top face 41, it is possible to improve wintry (or white) road performance until the winter indication means.
  • the bottom edge 54 of the protrusion 53 connecting with the incision face 51 (or 52) locates at least equal to 55% of the depth D of the groove 3 from the top face 41 when the tread 1 being brand new and the top edge 55 of the protrusion 53 connecting with the incision face 51 (or 52) and radially outward of the bottom edge 54 of the protrusion 53 locates at most equal to 30% of the depth D of the groove 3 from the top face 41 when the tread 1 being brand new
  • the protrusion 53 contributes to increase an area of the top face 41 (the contact face 2) to be in contact with wintry ground while increasing a length of an edge of the incision 5 when remaining tread depth is reached to a level of the protrusion 53. Therefore it is possible to improve further wintry (or white) road performance until the winter indication means.
  • the incision 5 When remaining tread depth is reached to a level of the bottom edge 54 of the protrusion 53, the incision 5 increases its width (distance t between two opposed incision faces 51, 52) for better evacuation of water. Therefore it is possible to improve normal (or black) road performance after the winter indication means.
  • bottom edge 54 of the protrusion 53 connecting with the incision face 51 (or 52) locates less than 55% of the depth D of the groove 3 from the top face 41 when the tread 1 being brand new, there is a risk that the protrusion 53 disappears before reaching to the winter indication means thus wintry (or white) road performance until the winter indication means cannot be improved.
  • this bottom edge 54 of the protrusion 53 connecting with the incision face 51 (or 52) being located at least equal to 55% of the depth D of the groove 3 from the top face 41 when the tread 1 being brand new, it is possible to improve wintry (or white) road performance until the winter indication means.
  • This bottom edge 54 of the protrusion 53 connecting with the incision face 51 (or 52) is preferably located at least equal to 60% of the depth D of the groove 3 from the top face 41 when the tread 1 being brand new, more preferably at least equal to 65% and at most equal to 80% of the depth D of the groove 3 from the top face 41 when the tread 1 being brand new.
  • top edge 55 of the protrusion 53 connecting with the incision face 51 (or 52) locates more than 30% of the depth D of the groove 3 from the top face 41 when the tread 1 being brand new, there is a risk that the protrusion 53 cannot contribute increase of stiffness of the contact element 4 even the protrusion 53 is in contact with another opposed incision face 52 (or 51), or cannot contribute increase of the length of the edge of the incision 5 thus wintry (or white) road performance until the winter indication means cannot be improved.
  • This top edge 55 of the protrusion 53 connecting with the incision face 51 (or 52) is preferably located at most equal to 25% of the depth D of the groove 3 from the top face 41 when the tread 1 being brand new, still more preferably at most equal to 20% of the depth D of the groove 3 from the top face 41 when the tread 1 being brand new.
  • top edge 55 of the protrusion 53 is radially inwardly offset from the top face 41 of the contact element 4, it is possible to increase productivity of the tread 1 as form of the incision 5 at the top face 41 when the tread 1 is brand new can be simpler.
  • top edge 55 of the protrusion 53 is at most equal to 1.5 mm radially inwardly offset from the top face 41 of the contact element 4, it is possible to improve wintry (or white) road performance until the winter indication means.
  • the distance t between the two opposed incision faces 51, 52 is between 0.8 mm and 3.0 mm, it is possible to improve normal (or black) road performance after the winter indication means while maintaining productivity of the incision provided with the protrusions and the tread having the incision.
  • this distance t between the two opposed incision faces 51, 52 is less than 0.8 mm, there is a risk that increase of the distance t between the two opposed incision faces 51, 52 when remaining tread depth is reached to the level of the bottom edge 54 of the protrusion 53 is insufficient for evacuating water thus degradation of normal (or black) road performance after the winter indication means. If this distance t between the two opposed incision faces 51, 52 is more than 3.0 mm, there is a risk that manufacturing of the incision 5 provided with the protrusions 53 and the tread 1 having the incision 5 becomes inefficient thus degradation of productivity.
  • This distance t between the two opposed incision faces 51, 52 is preferably between 0.8 mm and 2.5 mm, more preferably between 0.8 mm and 2.0 mm and still more preferably between 1.0 mm and 2.0 mm.
  • the protrusion amount p of the protrusion 53 is at least equal to 60% of the distance t between the two opposed incision faces 51, 52, and the protrusion amount p of the protrusion 53 is at least equal to 0.1 mm smaller than the distance t between the two opposed incision faces 51, 52, it is possible to improve wintry (or white) road performance until the winter indication means while maintaining productivity of the incision provided with the protrusions and the tread having the incision.
  • this protrusion amount p of the protrusion 53 is less than 60% of the distance t between the two opposed incision faces 51, 52, there is a risk that the protrusion 53 would not contact with another opposed incision face 52 (or 51) with loading, or contact occurs only with excessive deformation, which leads degradation of wintry (or white) road performance until the winter indication means. If this protrusion amount p of the protrusion 53 is less than 0.1 mm smaller than the distance t between the two opposed incision faces 51, 52, there is a risk that manufacturing of the incision 5 provided with the protrusions 53 and the tread 1 having the incision 5 becomes inefficient thus degradation of productivity.
  • the this protrusion amount p of the protrusion 53 is preferably at least equal to 65% of the distance t between the two opposed incision faces 51, 52, more preferably at least equal to 70% of the distance t between the two opposed incision faces 51, 52 and still more preferably at least equal to 80% of the distance t between the two opposed incision faces 51, 52.
  • this protrusion amount p of the protrusion 53 is preferably at least equal to 0.2 mm smaller than the distance t between the two opposed incision faces 51, 52, more preferably at least equal to 0.5 mm smaller than the distance t between the two opposed incision faces 51, 52 and still more preferably at least equal to 0.8 mm smaller than the distance t between the two opposed incision faces51, 52.
  • the bottom edge 54 of the protrusion 53 locates at least equal to 3.0 mm smaller than the depth D of the groove 3 from the top face 41, it is possible to provide improvement of normal (or black) road performance at appropriate timing after the winter indication means.
  • This bottom edge 54 of the protrusion 53 locates preferably at least equal to 3.2 mm smaller than the depth D of the groove 3 from the top face 41, more preferably at least equal to 3.5 mm smaller than the depth D of the groove 3 from the top face 41.
  • a shape of incision 5 may be curved, waved, zig-zagged or combination of these shapes including straight shape, and not only a shape on the contact face 2 but also a shape in radial orientation.
  • a shape of each the incision 5 may be the same, or may be different. In such the case, some of the incision 5 may be provided without the protrusions 53.
  • the protruding mount p of the protrusions 53 in the same incision 5 may be different one another.
  • a size, a shape of the protrusions 53 in circumferential, in axial or in radial orientation may be different one another.
  • the contact elements 4 may have an angle against circumferential orientation, and may have various shapes other than rectangle.
  • the incisions 5 may also have an angle against circumferential orientation, and may open to only one groove 3, or may open to no groove 3.
  • FIG. 5 is a schematic plan view of a portion of a tread for a tire according to a second embodiment of the present invention.
  • Fig. 6 is a schematic cross sectional view taken along line VI-VI in Fig. 5.
  • the constitution of the second embodiment is similar to that of the first embodiment other than the arrangement shown in Figs 5 & 6, thus description will be made referring to Figs 5 & 6.
  • the tread 21 having a contact face 22 is provided with a plurality of grooves 23 of a depth D (shown in Fig. 6) opening to the contact face 22.
  • the plurality of grooves 23 include circumferential grooves 23a extending generally in circumferential orientation and lateral grooves 23b extending generally in axial orientation.
  • the plurality of grooves 23 (the circumferential grooves 23a and the lateral grooves 23b) are delimiting a plurality of contact elements 24.
  • the contact element 24 comprises at least one incision (two incisions) 25, each the incision 25 is provided with at least two protrusions 253 extending alternately, in axial orientation, from one of two opposed incision face 251 (or 252) toward another incision face 252 (or 251) with a protrusion amount p.
  • the protrusions 253 is forming already a part of a top face 241 (the contact face 22) at the brand new state.
  • the protrusions 253 having no overlap on plan view of the contact element 24 but having an overlap on cut view of the contact element 24 (as shown in Fig. 6).
  • the protrusion 253 provided with the incision 5 extending from one of the incision face 251 (or 252) toward another incision face 252 (or 251) has a right trapezoid-like shape in a cross sectional view.
  • a radially external part of the protrusion 253 is flush with the top face 241 of the contact element 24 thus a top edge 255 is on the top face 241 of the contact element 24, a radially internal part of the protrusion 253 is extending curvilinearly upwardly from one of the incision face 251 (or 252) toward another incision face 252 (or 251).
  • the depth D of the groove 23 is 8.0 mm
  • the depth d of the incision 5 is 7.5 mm
  • a bottom edge 255 of the protrusion 253 locates 2.8 mm smaller than the depth D of the groove 23 thus 65% of the depth D.
  • the protrusions 253 in the same incision 25 adjacent in an extending direction of the incision 25 are protruding from different incision faces 251, 252, it is possible to increase a degree of freedom to design the contact element 24 provided with the incision 25 having the protrusions 253 for various performance required to a tire.

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Abstract

Present invention provides a tread for a tire provided with a plurality of grooves, a plurality of contact elements delimited by the grooves and at least one incision, the incision being provided with at least two protrusions protruding with a protrusion amount p being at least equal to 51% of the distance t between two opposed incision faces, the at least two protrusions having no overlap on plan view of the contact element but having an overlap on cut view of the contact element, a bottom edge of the protrusion connecting with the incision face locates at least equal to 55% of the depth D of the groove from the top face, and a top edge of the protrusion connecting with the incision face and radially outward of the bottom edge of the protrusion locates at most equal to 30% of the depth D of the groove from the top face.

Description

A TREAD WITH SIPE FOR MULTI PERFORMANCE
The present invention relates to a tread for a tire, in particular to a tread for a tire provided with an incision for improving wintry performance from brand new to middle worn state and wet performance at close to end of life.
In recent years to a tire so-called “studless” and/or “winter” tire which is suitable for driving on ice covered and/or snow covered wintry (or white) road, there is a desire to increase performance on normal (or black) road that is not covered by ice nor snow while still improving performance on wintry (or white) road.
The “studless” and/or “winter” tire is often provided with a wear indication means for wintry usage (a winter indication means) in a tread groove, so-called “platform”, “snow wear bar” and/or “snow platform”, which indicates that remaining tread depth becomes less effective for driving on wintry (or white) road. Even after reaching remaining tread depth to the winter indication means, the tire can be used for driving on normal (or black) road until reaching to a legal tread wear indicator, thus there is a desire to increase performance on wintry (or white) road until the winter indication means, and to increase performance on normal (or black) road after the winter indication means.
In order to improve wintry (or white) road performance until the winter indication means and normal (or black) road performance after the winter indication means, the “studless” and/or “winter” tire is often provided with two or more radially laminated different rubber layers, an outer rubber layer is designed for better wintry (or white) road performance, an inner rubber layer is designed for better normal (or black) road performance. However, controlling a height of such rubber layers corresponding to the winter indication means is very difficult; the inner rubber layer may appear before winter indication means, or the outer rubber layer may exist even after the winter indication means. Thus it is desirable to achieve such improvements by tread pattern design.
WO2009/077499 discloses a tread for a tire provided with an incision having a wide portion and a narrow portion alternately, and the wide portion extending radially toward depth direction.
WO2015/086622 discloses a tread for a tire provided with a cut out (an incision) comprising an internal part having a shape of a channel and an intermediate part is making a connection between the internal part and an external part.
WO2012/041876 discloses a tread for a tire provided with an incision having at least one protuberance in order to reduce a width of the incision.
However with the above arrangements, an improvement on wintry (or white) road performance until the winter indication means and on normal (or black) road performance after the winter indication means is not optimized.
WO2009/077499 WO2015/086622 WO2012/041876
Therefore, there is a need for a tread for a tire which improves wintry (or white) road performance until the winter indication means simultaneously with satisfactory normal (or black) road performance after the winter indication means.
Definitions:
A “radial direction/orientation” is a direction/orientation perpendicular to axis of rotation of the tire. This direction/orientation corresponds to thickness orientation of the tread.
An “axial direction/orientation” is a direction/orientation parallel to axis of rotation of the tire.
A “circumferential direction/orientation” is a direction/orientation which is tangential to any circle centered on axis of rotation. This direction/orientation is perpendicular to both the axial direction/orientation and the radial direction/orientation.
A “tire” means all types of elastic tire whether or not subjected to an internal pressure.
A “tread” of a tire means a quantity of rubber material bounded by lateral surfaces and by two main surfaces one of which is intended to come into contact with ground when the tire is rolling.
A “groove” is a space between two rubber faces/sidewalls which do not contact between themselves under usual rolling condition connected by another rubber face/ bottom. A groove has a width and a depth.
A “sipe”, also referred to as an “incision”, is a narrow cutout formed toward radially inwardly from a surface of a tread made by, for example a thin blade having a shape like a knife blade. A width of the incision at the surface of the tread is narrower than a groove, for example less than or equal to 3.0mm. This incision may, different from the groove, be partly or completely closed when such the incision is in a contact patch and under usual rolling condition.
It is thus an object of the invention to provide a tread for a tire provided with at least one incision, such the tread can provide improvement of wintry (or white) road performance until the winter indication means while still improving level of normal (or black) road performance after the winter indication means.
The present invention provides a tread for a tire having a contact face intended to come into contact with ground during rolling, the tread being provided with a plurality of grooves of a depth D opening to the contact face and a plurality of contact elements being delimited by the plurality of grooves, each the plurality of contact elements having a top face constituting a part of the contact face and at least one incision of a depth d opening to the top face and extending radially inward of the contact elements, the at least one incision being delimited via two opposed incision faces being distant with a distance t measured on the top face of the contact element when the tread being brand new, the at least one incision being provided with at least two protrusions extending from at least one of the two opposed incision faces towards another opposed incision faces, a protrusion amount p of the protrusion being at least equal to 51% of the distance t between the two opposed incision faces measured on a plane parallel to the top face, the at least two protrusions having no overlap on plan view of the contact element but having an overlap on cut view of the contact element, a bottom edge of the protrusion connecting with the incision face locates at least equal to 55% of the depth D of the groove from the top face when the tread being brand new, and a top edge of the protrusion connecting with the incision face and radially outward of the bottom edge of the protrusion locates at most equal to 30% of the depth D of the groove from the top face when the tread being brand new.
This arrangement provides improvement of wintry (or white) road performance until the winter indication means while still improving level of normal (or black) road performance after the winter indication means.
Since the at least one incision being provided with at least two protrusions extending from at least one of the two opposed incision faces towards another opposed incision faces, the protrusion amount p of the protrusion being at least equal to 51% of the distance t between the two opposed incision faces measured on the plane parallel to the top face, the protrusion would contact with another opposed incision face with loading resulting an increase of stiffness of the contact element for better use of the top face (the contact face) in contact with wintry ground. Therefore it is possible to improve wintry (or white) road performance until the winter indication means.
If the protrusion amount p of the protrusion is less than 51% of the distance t between the two opposed incision faces, there is a risk that the protrusion would not contact with another opposed incision face with loading, or contact occurs only with excessive deformation, which leads degradation of wintry (or white) road performance until the winter indication means. By setting this protrusion amount p of the protrusion at least equal to 51% of the distance t between the two opposed incision faces measured on the plane parallel to the top face, it is possible to improve wintry (or white) road performance until the winter indication means.
Since the at least two protrusions having no overlap on plan view of the contact element but having the overlap on cut view of the contact element, the bottom edge of the protrusion connecting with the incision face locates at least equal to 55% of the depth D of the groove from the top face when the tread being brand new and the top edge of the protrusion connecting with the incision face and radially outward of the bottom edge of the protrusion locates at most equal to 30% of the depth D of the groove from the top face when the tread being brand new, the protrusion contributes to increase an area of the top face (the contact face) to be in contact with wintry ground while increasing a length of an edge of the incision when remaining tread depth is reached to a level of the protrusion. Therefore it is possible to improve further wintry (or white) road performance until the winter indication means.
When remaining tread depth is reached to a level of the bottom edge of the protrusion, the incision increases its width (distance t between two opposed incision faces) for better evacuation of water. Therefore it is possible to improve normal (or black) road performance after the winter indication means.
If the bottom edge of the protrusion connecting with the incision face locates less than 55% of the depth D of the groove from the top face when the tread being brand new, there is a risk that the protrusion disappears before reaching to the winter indication means thus wintry (or white) road performance until the winter indication means cannot be improved. By setting this bottom edge of the protrusion connecting with the incision face being located at least equal to 55% of the depth D of the groove from the top face when the tread being brand new, it is possible to improve wintry (or white) road performance until the winter indication means.
This bottom edge of the protrusion connecting with the incision face is preferably located at least equal to 60% of the depth D of the groove from the top face when the tread being brand new, more preferably at least equal to 65% and at most equal to 80% of the depth D of the groove from the top face when the tread being brand new.
If the top edge of the protrusion connecting with the incision face locates more than 30% of the depth D of the groove from the top face when the tread being brand new, there is a risk that the protrusion cannot contribute increase of stiffness of the contact element even the protrusion is in contact with another opposed incision face, or cannot contribute increase of the length of the edge of the incision thus wintry (or white) road performance until the winter indication means cannot be improved. By setting this top edge of the protrusion connecting with the incision face and radially outward of the bottom edge of the protrusion being located at most equal to 30% of the depth D of the groove from the top face when the tread being brand new, it is possible to improve wintry (or white) road performance until the winter indication means.
This top edge of the protrusion connecting with the incision face is preferably located at most equal to 25% of the depth D of the groove from the top face when the tread being brand new, still more preferably at most equal to 20% of the depth D of the groove from the top face when the tread being brand new.
In another preferred embodiment, the protrusions in the same incision adjacent in an extending direction of the incision are protruding from different incision faces.
According to this arrangement, it is possible to increase a degree of freedom to design the contact element provided with the incision having the protrusions for various performance required to a tire.
In another preferred embodiment, the top edge of the protrusion is radially inwardly offset from the top face of the contact element.
According to this arrangement, it is possible to increase productivity of the tread as form of the incision at the top face when the tread is brand new can be simpler.
In another preferred embodiment, the top edge of the protrusion is at most equal to 1.5 mm radially inwardly offset from the top face of the contact element.
If this offset is more than 1.5 mm, there is a risk that the protrusion cannot contribute increase of stiffness of the contact element even the protrusion is in contact with another opposed incision face, or cannot contribute increase of the length of the edge of the incision thus wintry (or white) road performance until the winter indication means cannot be improved. By setting this offset at most equal to 1.5 mm radially inwardly from the top face of the contact element, it is possible to improve wintry (or white) road performance until the winter indication means.
In another preferred embodiment, the distance t between the two opposed incision faces is between 0.8 mm and 3.0 mm.
If this distance t between the two opposed incision faces is less than 0.8 mm, there is a risk that increase of the distance t between the two opposed incision faces when remaining tread depth is reached to the level of the bottom edge of the protrusion is insufficient for evacuating water thus degradation of normal (or black) road performance after the winter indication means. If this distance t between the two opposed incision faces is more than 3.0 mm, there is a risk that manufacturing of the incision provided with the protrusions and the tread having the incision becomes inefficient thus degradation of productivity. By setting this distance t between the two opposed incision faces between 0.8 mm and 3.0 mm, it is possible to improve normal (or black) road performance after the winter indication means while maintaining productivity of the incision provided with the protrusions and the tread having the incision.
This distance t between the two opposed incision faces is preferably between 0.8 mm and 2.5 mm, more preferably between 0.8 mm and 2.0 mm and still more preferably between 1.0 mm and 2.0 mm.
In another preferred embodiment, the protrusion amount p of the protrusion is at least equal to 60% of the distance t between the two opposed incision faces, and the protrusion amount p of the protrusion is at least equal to 0.1 mm smaller than the distance t between the two opposed incision faces.
If this protrusion amount p of the protrusion is less than 60% of the distance t between the two opposed incision faces, there is a risk that the protrusion would not contact with another opposed incision face with loading, or contact occurs only with excessive deformation, which leads degradation of wintry (or white) road performance until the winter indication means. If this protrusion amount p of the protrusion is less than 0.1 mm smaller than the distance t between the two opposed incision faces, there is a risk that manufacturing of the incision provided with the protrusions and the tread having the incision becomes inefficient thus degradation of productivity. By setting this protrusion amount p of the protrusion at least equal to 60% of the distance t between the two opposed incision faces and the protrusion amount p of the protrusion is at least equal to 0.1 mm smaller than the distance t between the two opposed incision faces, it is possible to improve wintry (or white) road performance until the winter indication means while maintaining productivity of the incision provided with the protrusions and the tread having the incision.
This protrusion amount p of the protrusion is preferably at least equal to 65% of the distance t between the two opposed incision faces, more preferably at least equal to 70% of the distance t between the two opposed incision faces and still more preferably at least equal to 80% of the distance t between the two opposed incision faces. And this protrusion amount p of the protrusion is preferably at least equal to 0.2 mm smaller than the distance t between the two opposed incision faces, more preferably at least equal to 0.5 mm smaller than the distance t between the two opposed incision faces and still more preferably at least equal to 0.8 mm smaller than the distance t between the two opposed incision faces.
In another preferred embodiment, the bottom edge of the protrusion locates at least equal to 3.0 mm smaller than the depth D of the groove from the top face.
If this bottom edge of the protrusion locates less than 3.0 mm smaller than the depth D of the groove from the top face, there is a risk that improvement of normal (or black) road performance is provided too late after the winter indication means. By setting this bottom edge of the protrusion being located at least equal to 3.0 mm smaller than the depth D of the groove from the top face, it is possible to provide improvement of normal (or black) road performance at appropriate timing after the winter indication means.
This bottom edge of the protrusion locates preferably at least equal to 3.2 mm smaller than the depth D of the groove from the top face, more preferably at least equal to 3.5 mm smaller than the depth D of the groove from the top face.
According to the arrangements described above, it is possible to provide a tread for a tire provided with at least one incision, such the tread can provide improvement of wintry (or white) road performance until the winter indication means while still improving level of normal (or black) road performance after the winter indication means.
Other characteristics and advantages of the invention arise from the description made hereafter in reference to the annexed drawings which show, as nonrestrictive examples, the embodiment of the invention.
In these drawings:
Fig. 1 is a schematic perspective view of a portion of a tread for a tire according to a first embodiment of the present invention; Fig. 2 is a schematic plan view of a portion of a tread for a tire according to the first embodiment of the present invention; Fig. 3 is a schematic cross sectional view taken along line III-III in Fig. 2; Fig. 4 is a schematic plan view of a portion of a tread for a tire worn out below winter indication means according to the first embodiment of the present invention; Fig. 5 is a schematic plan view of a portion of a tread for a tire according to a second embodiment of the present invention; Fig. 6 is a schematic cross sectional view taken along line VI-VI in Fig. 5;
Preferred embodiments of the present invention will be described below referring to the drawings.
A tread 1 for a tire according to a first embodiment of the present invention will be described referring to Figs. 1, 2, 3 and 4.
Fig. 1 is a schematic perspective view of a portion of a tread for a tire according to a first embodiment of the present invention. Fig. 2 is a schematic plan view of a portion of a tread for a tire according to the first embodiment of the present invention. Fig. 3 is a schematic cross sectional view taken along line III-III in Fig. 2. Fig. 4 is a schematic plan view of a portion of a tread for a tire worn out below winter indication means according to the first embodiment of the present invention.
The tread 1 is a tread for a tire having dimension 225/45R17 and comprises a contact face 2 intended to come into contact with the ground during rolling, and a plurality of grooves 3 of a depth D (shown in Fig. 3) opening to the contact face 2. The plurality of grooves 3 include circumferential grooves 3a extending generally in circumferential orientation (as indicated in Fig. 2) and lateral grooves 3b extending generally in axial orientation (as indicated in Fig. 2). The plurality of grooves 3 (the circumferential grooves 3a and the lateral grooves 3b) are delimiting a plurality of contact elements 4. Each the plurality of contact elements 4 having a top face 41 constituting a part of the contact face 2. The contact elements 4 also comprise at least one incision 5 of a depth d (shown in Fig. 3) opening to the top face 41 and extending radially inward of the contact elements 4.
As shown in Fig. 1, the at least one incision 5 being delimited via two opposed incision faces 51, 52 distant with a distance t (shown in Fig. 2) measured on the top face 41 of the contact element 4 when the tread 1 being brand new.
As shown in Fig. 2, the at least one incision (two incisions) 5 being provided with at least two protrusions 53 extending from at least one of the two opposed incision faces 51 (or 52) towards another opposed incision faces 52 (or 51) as to protruding circumferentially inward to a middle of the contact element 4. A protrusion amount p of the protrusion 53 being at least equal to 51% of the distance t between the two opposed incision faces 51, 52 measured on a plane parallel to the top face 41, the at least two protrusions 53 having no overlap on plan view of the contact element 4 but having an overlap on cut view of the contact element 4 (shown in Fig. 3).
The protrusions 53 have a trapezoid shape in plan view of the contact element 4, two protrusions 53 in the same incision 5 are offset each other in axial orientation, axial ends of the protrusions 53 on the incision face 51 (or 52) are both offset from the groove 3 (circumferential groove 3a). In this present embodiment, two protrusions 53 are provided on one incision face 51 (or 52), the distance t between the two opposed incision faces 51, 52 is 1.0 mm thus between 0.8 mm and 3.0 mm, the protrusion amount p of the protrusion 52 is 0.7 mm, thus at least equal to 60% of the distance t between the two opposed incision faces 51, 52, and is at least equal to 0.1 mm smaller than the distance t between the two opposed incision faces 51, 52.
As shown in Fig. 3, the protrusion 53 provided with the incision 5 extending from one of the incision face 51 (or 52) toward another incision face 52 (or 51) has a right trapezoid shape in a cross sectional view. A radially external part of the protrusion 53 is substantially parallel to the top face 41 of the contact element 4, a radially internal part of the protrusion 53 is extending upwardly from one of the incision face 51 (or 52) toward another incision face 52 (or 51). A bottom edge 54 of the protrusion 53 connecting with the incision face 51 (or 52) locates at least equal to 55% of the depth D of the groove 3 from the top face 41 when the tread 1 being brand new and at least equal to 3.0 mm smaller than the depth D of the groove 3 from the top face 41, and a top edge 55 of the protrusion 53 connecting with the incision face 51 (or 52) radially outward of the bottom edge 54 of the protrusion 53 is radially inwardly offset from the top face 41 of the contact element 4, the top edge 55 of the protrusion 53 locates at most equal to 30% of the depth D of the groove 3 from the top face 41 when the tread 1 being brand new. In this present embodiment, the depth D of the groove 3 is 8.0 mm, the depth d of the incision 5 is 7.0 mm, the bottom edge 55 of the protrusion 53 locates 2.4 mm smaller than the depth D of the groove 3 thus 70% of the depth D, the top edge 55 of the protrusion 53 is 1.0 mm offset from the top face 41 thus at most equal to 1.5 mm radially inwardly offset from the top face 41 of the contact element 4.
As shown in Fig. 4, when the contact element 4 worn out to a level beyond the winter indication means, a worn top face 41’ (a worn contact face 2’) appears and the protrusions 53 provided with the incision 5 disappears. At this state, the incision 5 increases the distance t between the two opposed incision faces 51, 52 compared with that of before the winter indication means, as the protrusions 53 provided with the incision 5 disappears with wear.
Since the at least one incision 5 being provided with at least two protrusions 53 extending from at least one of the two opposed incision faces 51 (or 52) towards another opposed incision faces 52 (or 51), the protrusion amount p of the protrusion 53 being at least equal to 51% of the distance t between the two opposed incision faces 51, 52 measured on the plane parallel to the top face 41, the protrusion 53 would contact with another opposed incision face 52 (or 51) with loading resulting an increase of stiffness of the contact element 4 for better use of the top face 41 (the contact face 2) in contact with wintry ground. Therefore it is possible to improve wintry (or white) road performance until the winter indication means.
If the protrusion amount p of the protrusion 53 is less than 51% of the distance t between the two opposed incision faces 51, 52, there is a risk that the protrusion 53 would not contact with another opposed incision face 52 (or 51) with loading, or contact occurs only with excessive deformation, which leads degradation of wintry (or white) road performance until the winter indication means. By setting this protrusion amount p of the protrusion 53 at least equal to 51% of the distance t between the two opposed incision faces 51, 52 measured on the plane parallel to the top face 41, it is possible to improve wintry (or white) road performance until the winter indication means.
Since the at least two protrusions 53 having no overlap on plan view of the contact element 4 but having the overlap on cut view of the contact element 4, the bottom edge 54 of the protrusion 53 connecting with the incision face 51 (or 52) locates at least equal to 55% of the depth D of the groove 3 from the top face 41 when the tread 1 being brand new and the top edge 55 of the protrusion 53 connecting with the incision face 51 (or 52) and radially outward of the bottom edge 54 of the protrusion 53 locates at most equal to 30% of the depth D of the groove 3 from the top face 41 when the tread 1 being brand new, the protrusion 53 contributes to increase an area of the top face 41 (the contact face 2) to be in contact with wintry ground while increasing a length of an edge of the incision 5 when remaining tread depth is reached to a level of the protrusion 53. Therefore it is possible to improve further wintry (or white) road performance until the winter indication means.
When remaining tread depth is reached to a level of the bottom edge 54 of the protrusion 53, the incision 5 increases its width (distance t between two opposed incision faces 51, 52) for better evacuation of water. Therefore it is possible to improve normal (or black) road performance after the winter indication means.
If the bottom edge 54 of the protrusion 53 connecting with the incision face 51 (or 52) locates less than 55% of the depth D of the groove 3 from the top face 41 when the tread 1 being brand new, there is a risk that the protrusion 53 disappears before reaching to the winter indication means thus wintry (or white) road performance until the winter indication means cannot be improved. By setting this bottom edge 54 of the protrusion 53 connecting with the incision face 51 (or 52) being located at least equal to 55% of the depth D of the groove 3 from the top face 41 when the tread 1 being brand new, it is possible to improve wintry (or white) road performance until the winter indication means.
This bottom edge 54 of the protrusion 53 connecting with the incision face 51 (or 52) is preferably located at least equal to 60% of the depth D of the groove 3 from the top face 41 when the tread 1 being brand new, more preferably at least equal to 65% and at most equal to 80% of the depth D of the groove 3 from the top face 41 when the tread 1 being brand new.
If the top edge 55 of the protrusion 53 connecting with the incision face 51 (or 52) locates more than 30% of the depth D of the groove 3 from the top face 41 when the tread 1 being brand new, there is a risk that the protrusion 53 cannot contribute increase of stiffness of the contact element 4 even the protrusion 53 is in contact with another opposed incision face 52 (or 51), or cannot contribute increase of the length of the edge of the incision 5 thus wintry (or white) road performance until the winter indication means cannot be improved. By setting this top edge 55 of the protrusion 53 connecting with the incision face 51 (or 52) and radially outward of the bottom edge 54 of the protrusion 53 being located at most equal to 30% of the depth D of the groove 3 from the top face 41 when the tread 1 being brand new, it is possible to improve wintry (or white) road performance until the winter indication means.
This top edge 55 of the protrusion 53 connecting with the incision face 51 (or 52) is preferably located at most equal to 25% of the depth D of the groove 3 from the top face 41 when the tread 1 being brand new, still more preferably at most equal to 20% of the depth D of the groove 3 from the top face 41 when the tread 1 being brand new.
As the top edge 55 of the protrusion 53 is radially inwardly offset from the top face 41 of the contact element 4, it is possible to increase productivity of the tread 1 as form of the incision 5 at the top face 41 when the tread 1 is brand new can be simpler.
As the top edge 55 of the protrusion 53 is at most equal to 1.5 mm radially inwardly offset from the top face 41 of the contact element 4, it is possible to improve wintry (or white) road performance until the winter indication means.
If this offset is more than 1.5 mm, there is a risk that the protrusion 53 cannot contribute increase of stiffness of the contact element 4 even the protrusion 53 is in contact with another opposed incision face 52 (or 51), or cannot contribute increase of the length of the edge of the incision 5 thus wintry (or white) road performance until the winter indication means cannot be improved.
As the distance t between the two opposed incision faces 51, 52 is between 0.8 mm and 3.0 mm, it is possible to improve normal (or black) road performance after the winter indication means while maintaining productivity of the incision provided with the protrusions and the tread having the incision.
If this distance t between the two opposed incision faces 51, 52 is less than 0.8 mm, there is a risk that increase of the distance t between the two opposed incision faces 51, 52 when remaining tread depth is reached to the level of the bottom edge 54 of the protrusion 53 is insufficient for evacuating water thus degradation of normal (or black) road performance after the winter indication means. If this distance t between the two opposed incision faces 51, 52 is more than 3.0 mm, there is a risk that manufacturing of the incision 5 provided with the protrusions 53 and the tread 1 having the incision 5 becomes inefficient thus degradation of productivity.
This distance t between the two opposed incision faces 51, 52 is preferably between 0.8 mm and 2.5 mm, more preferably between 0.8 mm and 2.0 mm and still more preferably between 1.0 mm and 2.0 mm.
As the protrusion amount p of the protrusion 53 is at least equal to 60% of the distance t between the two opposed incision faces 51, 52, and the protrusion amount p of the protrusion 53 is at least equal to 0.1 mm smaller than the distance t between the two opposed incision faces 51, 52, it is possible to improve wintry (or white) road performance until the winter indication means while maintaining productivity of the incision provided with the protrusions and the tread having the incision.
If this protrusion amount p of the protrusion 53 is less than 60% of the distance t between the two opposed incision faces 51, 52, there is a risk that the protrusion 53 would not contact with another opposed incision face 52 (or 51) with loading, or contact occurs only with excessive deformation, which leads degradation of wintry (or white) road performance until the winter indication means. If this protrusion amount p of the protrusion 53 is less than 0.1 mm smaller than the distance t between the two opposed incision faces 51, 52, there is a risk that manufacturing of the incision 5 provided with the protrusions 53 and the tread 1 having the incision 5 becomes inefficient thus degradation of productivity.
The this protrusion amount p of the protrusion 53 is preferably at least equal to 65% of the distance t between the two opposed incision faces 51, 52, more preferably at least equal to 70% of the distance t between the two opposed incision faces 51, 52 and still more preferably at least equal to 80% of the distance t between the two opposed incision faces 51, 52. And this protrusion amount p of the protrusion 53 is preferably at least equal to 0.2 mm smaller than the distance t between the two opposed incision faces 51, 52, more preferably at least equal to 0.5 mm smaller than the distance t between the two opposed incision faces 51, 52 and still more preferably at least equal to 0.8 mm smaller than the distance t between the two opposed incision faces51, 52.
As the bottom edge 54 of the protrusion 53 locates at least equal to 3.0 mm smaller than the depth D of the groove 3 from the top face 41, it is possible to provide improvement of normal (or black) road performance at appropriate timing after the winter indication means.
If this bottom edge 54 of the protrusion 53 locates less than 3.0 mm smaller than the depth D of the groove 3 from the top face 41, there is a risk that improvement of normal (or black) road performance is provided too late after the winter indication means.
This bottom edge 54 of the protrusion 53 locates preferably at least equal to 3.2 mm smaller than the depth D of the groove 3 from the top face 41, more preferably at least equal to 3.5 mm smaller than the depth D of the groove 3 from the top face 41.
A shape of incision 5 may be curved, waved, zig-zagged or combination of these shapes including straight shape, and not only a shape on the contact face 2 but also a shape in radial orientation. In case multiple incisions 5 are provided in the same contact element 4, a shape of each the incision 5 may be the same, or may be different. In such the case, some of the incision 5 may be provided without the protrusions 53.
The protruding mount p of the protrusions 53 in the same incision 5 may be different one another. A size, a shape of the protrusions 53 in circumferential, in axial or in radial orientation may be different one another.
The contact elements 4 may have an angle against circumferential orientation, and may have various shapes other than rectangle. The incisions 5 may also have an angle against circumferential orientation, and may open to only one groove 3, or may open to no groove 3.
A tread 21 for a tire according to a second embodiment of the present invention will be described referring to Fig. 5 and Fig. 6. Fig. 5 is a schematic plan view of a portion of a tread for a tire according to a second embodiment of the present invention. Fig. 6 is a schematic cross sectional view taken along line VI-VI in Fig. 5. The constitution of the second embodiment is similar to that of the first embodiment other than the arrangement shown in Figs 5 & 6, thus description will be made referring to Figs 5 & 6.
In the second embodiment, the tread 21 having a contact face 22 is provided with a plurality of grooves 23 of a depth D (shown in Fig. 6) opening to the contact face 22. The plurality of grooves 23 include circumferential grooves 23a extending generally in circumferential orientation and lateral grooves 23b extending generally in axial orientation. The plurality of grooves 23 (the circumferential grooves 23a and the lateral grooves 23b) are delimiting a plurality of contact elements 24.
As shown in Fig. 5, the contact element 24 comprises at least one incision (two incisions) 25, each the incision 25 is provided with at least two protrusions 253 extending alternately, in axial orientation, from one of two opposed incision face 251 (or 252) toward another incision face 252 (or 251) with a protrusion amount p. The protrusions 253 is forming already a part of a top face 241 (the contact face 22) at the brand new state. The protrusions 253 having no overlap on plan view of the contact element 24 but having an overlap on cut view of the contact element 24 (as shown in Fig. 6).
As shown in Fig. 6, the protrusion 253 provided with the incision 5 extending from one of the incision face 251 (or 252) toward another incision face 252 (or 251) has a right trapezoid-like shape in a cross sectional view. A radially external part of the protrusion 253 is flush with the top face 241 of the contact element 24 thus a top edge 255 is on the top face 241 of the contact element 24, a radially internal part of the protrusion 253 is extending curvilinearly upwardly from one of the incision face 251 (or 252) toward another incision face 252 (or 251). In this present embodiment, the depth D of the groove 23 is 8.0 mm, the depth d of the incision 5 is 7.5 mm, a bottom edge 255 of the protrusion 253 locates 2.8 mm smaller than the depth D of the groove 23 thus 65% of the depth D.
As the protrusions 253 in the same incision 25 adjacent in an extending direction of the incision 25 are protruding from different incision faces 251, 252, it is possible to increase a degree of freedom to design the contact element 24 provided with the incision 25 having the protrusions 253 for various performance required to a tire.
The invention is not limited to the examples described and represented and various modifications can be made there without leaving its framework.
1, 21 tread
2, 22 contact face
3, 23 groove
3a, 23a circumferential groove
3b, 23b axial groove
4, 24 contact element
41, 241 top face
5, 25 incision
51, 52, 251, 252 incision face
53, 253 protrusion

Claims (8)

  1. A tread (1) for a tire having a contact face (2) intended to come into contact with ground during rolling, the tread (1) being provided with a plurality of grooves (3) of a depth D opening to the contact face (2) and a plurality of contact elements (4) being delimited by the plurality of grooves (3), each the plurality of contact elements (4) having a top face (41) constituting a part of the contact face (2) and at least one incision (5) of a depth d opening to the top face (41) and extending radially inward of the contact elements (4),
    the at least one incision (5) being delimited via two opposed incision faces (51, 52) being distant with a distance t measured on the top face (41) of the contact element (4) when the tread (1) being brand new, the at least one incision (5) being provided with at least two protrusions (53) extending from at least one of the two opposed incision faces (51, 52) towards another opposed incision faces (52, 51), a protrusion amount p of the protrusion (53) being at least equal to 51% of the distance t between the two opposed incision faces (51, 52) measured on a plane parallel to the top face (41), the at least two protrusions (53) having no overlap on plan view of the contact element (4) but having an overlap on cut view of the contact element (4),
    the tread being characterized in that a bottom edge (54) of the protrusion (53) connecting with the incision face (51, 52) locates at least equal to 55% of the depth D of the groove (3) from the top face (41) when the tread (1) being brand new, and in that a top edge (55) of the protrusion (53) connecting with the incision face (51, 52) and radially outward of the bottom edge of the protrusion (53) locates at most equal to 30% of the depth D of the groove (3) from the top face (41) when the tread (1) being brand new.
  2. The tread (1) according to claim 1, wherein the protrusions (53) in the same incision (5) adjacent in an extending direction of the incision (5) are protruding from different incision faces (51, 52).
  3. The tread (1) according to claim 1 or claim 2, wherein the top edge (55) of the protrusion (53) is radially inwardly offset from the top face (41) of the contact element (4).
  4. The tread (1) according to claim 3, wherein the top edge (55) of the protrusion (53) is at most equal to 1.5 mm radially inwardly offset from the top face (41) of the contact element (4).
  5. The tread (1) according to any one of the claims 1 to 4, wherein the distance t between the two opposed incision faces (51, 52) is between 0.8 mm and 3.0 mm.
  6. The tread (1) according to any one of the claims 1 to 5, wherein the protrusion amount p of the protrusion (53) is at least equal to 60% of the distance t between the two opposed incision faces (51, 52), and wherein the protrusion amount p of the protrusion (53) is at least equal to 0.1 mm smaller than the distance t between the two opposed incision faces (51, 52).
  7. The tread (1) according to any one of the claims 1 to 6, wherein the bottom edge (54) of the protrusion (53) locates at least equal to 3.0 mm smaller than the depth D of the groove (3) from the top face (41).
  8. A tire having a tread according to any one of the claims 1 to 7.

PCT/JP2017/045690 2017-12-20 2017-12-20 A tread with sipe for multi performance WO2019123561A1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
PCT/JP2017/045690 WO2019123561A1 (en) 2017-12-20 2017-12-20 A tread with sipe for multi performance

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/JP2017/045690 WO2019123561A1 (en) 2017-12-20 2017-12-20 A tread with sipe for multi performance

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Publication Number Publication Date
WO2019123561A1 true WO2019123561A1 (en) 2019-06-27

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP3974209A1 (en) * 2020-09-23 2022-03-30 Sumitomo Rubber Industries, Ltd. Tire

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2002316517A (en) * 2001-04-24 2002-10-29 Toyo Tire & Rubber Co Ltd Pneumatic tire
JP2008290521A (en) * 2007-05-23 2008-12-04 Yokohama Rubber Co Ltd:The Pneumatic tire
JP2009126293A (en) * 2007-11-21 2009-06-11 Yokohama Rubber Co Ltd:The Pneumatic tire
US20110290393A1 (en) * 2008-12-05 2011-12-01 Michelin Recherche Et Technique S.A. Tire Tread Comprising Incisions Provided with Projections
WO2012041876A1 (en) * 2010-09-30 2012-04-05 Societe De Technologie Michelin Improved tyre tread

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2002316517A (en) * 2001-04-24 2002-10-29 Toyo Tire & Rubber Co Ltd Pneumatic tire
JP2008290521A (en) * 2007-05-23 2008-12-04 Yokohama Rubber Co Ltd:The Pneumatic tire
JP2009126293A (en) * 2007-11-21 2009-06-11 Yokohama Rubber Co Ltd:The Pneumatic tire
US20110290393A1 (en) * 2008-12-05 2011-12-01 Michelin Recherche Et Technique S.A. Tire Tread Comprising Incisions Provided with Projections
WO2012041876A1 (en) * 2010-09-30 2012-04-05 Societe De Technologie Michelin Improved tyre tread

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP3974209A1 (en) * 2020-09-23 2022-03-30 Sumitomo Rubber Industries, Ltd. Tire

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