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US 7,350,552 B2Granted
Directional tread having incisions of varying inclination
AssigneeMichelin Recherche et Technique S.A.
InventorRobert Radulescu
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AssigneeMichelin Recherche et Technique S.A.
InventorRobert Radulescu
Estimating the term…
A tread (1) for steer axle tires for a heavy vehicle, the tire having a preferred direction of travel, the tread comprising grooves (2) of generally circumferential orientation defining at least three ribs (30, 31, 32, 33, 34), two of the ribs forming the edges (30, 34) of the tread, some of the intermediate ribs (31, 32, 33) being provided with a plurality of incisions (41, 42, 43), of general transverse orientation and substantially parallel to each other, the incisions having an average inclination other than zero relative to the direction perpendicular to the running surface of a new tread, this tread being characterised in that, when viewed in a section plane perpendicular to the axis of rotation of the tyre, the incisions in the intermediate ribs form, on and in the vicinity of the running surface when new of the tread, an angle close to or equal to 0° with a line perpendicular to said surface at the point of intersection, whereas the angle of each of these incisions increases in the depth of the tread.
A steer axle tire for a heavy vehicle, the tire designed for a single rolling direction and comprising a radial carcass reinforcement surmounted by a crown reinforcement and a tread, the tire including a visual indicator indicating the single rolling direction, the tread comprising ribs separated by grooves of generally circumferential orientation, two of said ribs forming the edges of the tread, and at least two of said ribs being intermediate such two edge ribs, the intermediate ribs having a plurality of incisions, all incisions being V-shaped and oriented in the same direction, each incision being of a width of less than 3 mm, a depth E when the tread is new and substantially parallel to each other, wherein each incision has an angular relationship with a line extending perpendicular to the point where the incision intersects the tread's outer surface, the angular relationship varying along the incision wherein the angular relationship in an outer tread region extending from the outer surface to a depth of one-third E is zero degrees, and the angular relationship in an inner tread region at a depth greater than one-third E being greater than the angular relationship in the outer tread region, wherein a radially innermost first point of each incision is located, relative to the indicated rolling direction of the tire, in front of a second point of the incision located on the running surface of the tread when new, wherein each incision, from its second point to its first point, has a generally concave side and a generally convex side, the generally concave side facing in the rolling direction and further wherein the two edge ribs are free of incisions having varying inclination.
A steer axle tire for a heavy vehicle, the tire designed for a single rolling direction and comprising a radial carcass reinforcement surmounted by a crown reinforcement, and a tread ,the tire having means indicating the single rolling direction, the tread comprising ribs separated by grooves of generally circumferential orientation, two of said ribs forming the edges of the tread, at least two of said ribs being intermediate to such two ribs, each intermediate rib having a plurality of incisions, all incisions being V-shaped and oriented in the same direction, each incision being of a width of less than 3 mm, a depth F when the tire is new and being substantially parallel to each other, wherein, each incision has a varying inclination, being oriented relative to a line perpendicular to an outer surface of the tread at a first angle of zero degrees from the outer surface to a depth of one-third E when the tread is new, and at a second angle greater than said first angle at a depth greater than one-third E, wherein, a radially innermost first point of each incision is located, relative to the indicated rolling direction of the tire, in front of a second point of the incision located on the outer surface of the tread when new, wherein each incision from its second point to its first point, has a generally concave side convex side, the generally concave side facing in the rolling direction, and further wherein the edge ribs are not provided with incisions of varying inclination, the incisions are spaced in the circumferential direction with a pitch p which satisfies the following relationship:
Dependencies are inferred from the claim text.
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From the US filing history. Foreign family members aren’t listed.
In which the raised area of the pattern consists only of continuous circumferential ribs, e.g. zig-zag: further characterised by the groove…
Patterns comprising block rows or discontinuous ribs: further characterised by the groove cross-section
Tread patterns: characterised by the use of narrow slits or incisions, e.g. sipes
With special shape of the sipe: three-dimensional shape with regard to depth and extending direction
Term ended 7 Jan 2022 (estimated)
The present invention relates to treads for tires intended to be fitted on the front axle of transport vehicles and more particularly heavy vehicles, for example, long haul trucks for highway use.
Tires for heavy vehicles typically comprise a carcass reinforcement comprising a plurality of reinforcements arranged radially, the carcass reinforcement itself being surmounted by a crown reinforcement extending in the circumferential direction. This crown reinforcement is composed of at least two plies superposed on one another, each ply being formed of a rubber mix reinforced by a plurality of cables or cords of low extensibility, preferably made of steel, arranged parallel to each other in one and the same ply and in a direction forming an angle with the tire circumferential direction at most equal to 40°, the cables from one ply to the other being crossed between each other. This crown reinforcement may further include, on one hand, two half-plies formed of cables of low extensibility forming with the circumferential direction an angle of between 45° and 80°, and on the other hand, at least one ply formed of so-called “elastic” cables placed radially to the outside of the crown plies, the reinforcement cables of which form an angle of less than 40°.
The crown reinforcement is furthermore surmounted on its radially outer surface by a tread formed with at least one rubber mix, the radially outer surface of which forms the running surface intended to come into contact with the roadway during travel of said tire.
Other characteristics and advantages of the invention will become apparent from the description given hereafter with reference to the appended figures, which show, by way of non-limitative examples, forms of embodiment of the subject of the invention.
FIG. 1 shows a plan view of part of a tread for a heavy vehicle according to the invention;
FIG. 2 shows a sectional view along the line II-II through the tread shown in FIG. 1;
In FIG. 1, there is shown part of the running surface S of a tread 1 of a tire according to the invention intended for the front axle of a heavy vehicle. This tread 1 comprises three main grooves 2 oriented circumferentially, these three grooves having a depth H of 18 mm. These grooves 2 define three intermediate ribs 31, 32, 33 and two edge ribs 30, 34, each edge rib axially limiting the contact zone of the tread with the roadway during travel of the tire. The intermediate ribs positioned between the edge ribs are provided with a plurality of incisions 41, 42, 43 of varying inclination in the direction of the thickness or depth of the tread and passing through each of said intermediate ribs on either side. These incisions have, on the running surface S, a V-shaped trace the toe or apex of which is directed in the preferred direction of rotation (marked by the arrow R) of the tire provided with this tread.
In order to obtain a satisfactory effect on the wear of the edge ribs, it is preferable for the incisions of varying inclination to be arranged on at least one of the intermediate ribs and at an average pitch p such that the ratio k,
k = Sne Se · p H satisfies the following relationship: 0.5≦k≦4 where Sne is the total of the surface areas of the ribs not provided with incisions of varying inclination according to the invention (edge ribs and possibly other intermediate ribs), Se is the total of the surface areas of the ribs provided with incisions of varying inclination according to the invention, and H is the average depth of the longitudinal grooves.