WO2020025685A1 - Pneumatic tire with optimized crown architecture - Google Patents
Pneumatic tire with optimized crown architecture Download PDFInfo
- Publication number
- WO2020025685A1 WO2020025685A1 PCT/EP2019/070652 EP2019070652W WO2020025685A1 WO 2020025685 A1 WO2020025685 A1 WO 2020025685A1 EP 2019070652 W EP2019070652 W EP 2019070652W WO 2020025685 A1 WO2020025685 A1 WO 2020025685A1
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- WIPO (PCT)
- Prior art keywords
- layer
- equal
- tire
- radially
- hooping
- Prior art date
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Classifications
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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
- B60C9/00—Reinforcements or ply arrangement of pneumatic tyres
- B60C9/18—Structure or arrangement of belts or breakers, crown-reinforcing or cushioning layers
- B60C9/28—Structure or arrangement of belts or breakers, crown-reinforcing or cushioning layers characterised by the belt or breaker dimensions or curvature relative to carcass
-
- 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
- B60C3/00—Tyres characterised by the transverse section
- B60C3/04—Tyres characterised by the transverse section characterised by the relative dimensions of the section, e.g. low profile
-
- 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
- B60C9/00—Reinforcements or ply arrangement of pneumatic tyres
- B60C9/18—Structure or arrangement of belts or breakers, crown-reinforcing or cushioning layers
- B60C9/20—Structure or arrangement of belts or breakers, crown-reinforcing or cushioning layers built-up from rubberised plies each having all cords arranged substantially parallel
- B60C9/22—Structure or arrangement of belts or breakers, crown-reinforcing or cushioning layers built-up from rubberised plies each having all cords arranged substantially parallel the plies being arranged with all cords disposed along the circumference of the tyre
- B60C9/2204—Structure or arrangement of belts or breakers, crown-reinforcing or cushioning layers built-up from rubberised plies each having all cords arranged substantially parallel the plies being arranged with all cords disposed along the circumference of the tyre obtained by circumferentially narrow strip winding
-
- 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
- B60C9/00—Reinforcements or ply arrangement of pneumatic tyres
- B60C9/18—Structure or arrangement of belts or breakers, crown-reinforcing or cushioning layers
- B60C9/20—Structure or arrangement of belts or breakers, crown-reinforcing or cushioning layers built-up from rubberised plies each having all cords arranged substantially parallel
- B60C9/22—Structure or arrangement of belts or breakers, crown-reinforcing or cushioning layers built-up from rubberised plies each having all cords arranged substantially parallel the plies being arranged with all cords disposed along the circumference of the tyre
- B60C2009/2214—Structure or arrangement of belts or breakers, crown-reinforcing or cushioning layers built-up from rubberised plies each having all cords arranged substantially parallel the plies being arranged with all cords disposed along the circumference of the tyre characterised by the materials of the zero degree ply cords
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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
- B60C9/00—Reinforcements or ply arrangement of pneumatic tyres
- B60C9/18—Structure or arrangement of belts or breakers, crown-reinforcing or cushioning layers
- B60C9/20—Structure or arrangement of belts or breakers, crown-reinforcing or cushioning layers built-up from rubberised plies each having all cords arranged substantially parallel
- B60C9/22—Structure or arrangement of belts or breakers, crown-reinforcing or cushioning layers built-up from rubberised plies each having all cords arranged substantially parallel the plies being arranged with all cords disposed along the circumference of the tyre
- B60C2009/2238—Physical properties or dimensions of the ply coating rubber
- B60C2009/2247—Thickness
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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
- B60C11/0008—Tyre tread bands; Tread patterns; Anti-skid inserts characterised by the tread rubber
- B60C2011/0016—Physical properties or dimensions
- B60C2011/0033—Thickness of the tread
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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
- B60C2200/00—Tyres specially adapted for particular applications
- B60C2200/04—Tyres specially adapted for particular applications for road vehicles, e.g. passenger cars
Definitions
- the present invention relates to a tire intended to be mounted on a passenger vehicle, and more particularly the top of such a tire.
- a tire having a geometry of revolution relative to an axis of rotation the geometry of the tire is generally described in a meridian plane containing the axis of rotation of the tire.
- the radial, axial and circumferential directions respectively designate the directions perpendicular to the axis of rotation of the tire, parallel to the axis of rotation of the tire and perpendicular to the meridian plane.
- the median circumferential plane called the equator plane, divides the tire into two substantially symmetrical half toroids, the tire possibly having asymmetries in tread, in architecture, linked to manufacturing precision or to sizing.
- the expressions “radially inside” and “radially outside” mean respectively “closer to the axis of rotation of the tire, in the radial direction, than” and “further from the axis of rotation of the tire, in the radial direction, that ".
- the expressions “axially inside of” and “axially outside of” mean respectively “closer to the equator plane, in the axial direction, than” and “further away from the equator plane, in the axial direction, than”.
- a “radial distance” is a distance from the axis of rotation of the tire, and an “axial distance” is a distance from the equatorial plane of the tire.
- a “radial thickness” is measured in the radial direction, and an “axial width” is measured in the axial direction.
- a tire comprises a crown comprising a tread intended to come into contact with the ground by means of a running surface, two beads intended to come into contact with a rim and two sidewalls connecting the crown to the beads.
- a tire comprises a carcass reinforcement comprising at least one carcass layer, radially interior at the top and connecting the two beads.
- the tread is further formed by one or more mixtures or rubber compounds.
- rubber mixture or “rubber compound” designates a rubber composition comprising at least one elastomer and a filler.
- the crown comprises at least one crown reinforcement radially inside the tread.
- the crown reinforcement comprises at least one reinforcement of work comprising at least one working layer composed of reinforcing elements parallel to each other forming, with the circumferential direction, an angle between 15 ° and 50 °.
- the invention relates to tires, the crown reinforcement of which comprises a hooping reinforcement comprising at least one hooping layer composed of reinforcing elements forming, with the circumferential direction, an angle between 0 ° and 10 °, the hooping reinforcement being most often but not necessarily radially external to the working layers.
- radially outer surface (SRE) of said layer passes through the most radially outer point of each element of reinforcement, of each meridian.
- SRI radially inner surface
- the radial distance is measured from the radially exterior surface SRE at this point, and respectively from the radially interior surface SRI at the other measurement point if this is radially inside the layer of reinforcing elements.
- a cutout designates either a well, a groove, an incision, or a circumferential groove and forms a space opening onto the rolling surface and delimited radially internally by a cutout bottom.
- An incision or a groove has, on the running surface, two main characteristic dimensions: a width W and a length Lo, such that the length Lo is at least equal to twice the width W.
- An incision or a groove is therefore delimited by at least two main lateral faces determining its length Lo and connected by a bottom face, the two main lateral faces being distant from each other by a non-zero distance, called width W of the incision or the groove.
- the depth of a cutout is the maximum distance between the running surface and the bottom of the cutout. This maximum distance being measured in a direction orthogonal both to the rolling surface and to the bottom of the cut.
- the expression “overhanging” means, “for each meridian, radially exterior within the limit of the axial coordinates delimited by”.
- the most radially outer points of the hooping layer overhanging the most axially outer points of the most radially outer working layer denote for each meridian, the set of the most radially outer points of the hooping layer radially exterior to the most axially exterior points of the most radially exterior working layer, within the limit of the axial coordinates of the latter.
- a tire must meet multiple performance criteria relating to phenomena such as endurance, uniformity, rolling resistance.
- a large number of tires are fitted with a hoop layer.
- These hooping layers have a very high rigidity in extension in the circumferential direction and allow the centrifugal forces to be taken up at high speed.
- the hooping layer is placed in a strip of several wires of a width LB measured perpendicular to the reinforcing elements of said strip. The wider the strip, the less turns it takes and therefore the manufacturing time to go continuously from one of the axial ends of the crown reinforcement to the other.
- the difficulty is that the wider the strip of the hooping layer, the greater the edge effects because the width from the axial end of the hooping layer to the equatorial plane varies around the wheel from the width of the laying strip. . This variation has an influence on the uniformity of tires and their endurance at high speed.
- the working layers must have a substantially constant radius between the center and the shoulders of the tire, which facilitates flattening.
- the extra thickness of a dead turn of the band of the hooping layer is closer to the rolling surface than the hooping layer in the center of a tire, and could be attacked when rolling over an object on the ground. of rolling. In addition, this extra thickness reduces the volume of the tread on the shoulder area.
- the tires thus designed arrive at the wear limit in more than 80% of the cases with the shoulder zones at the wear limit and a central zone that can still cover several thousand kilometers.
- the solution used in the state of the art is therefore to design the tire such that the radius of the working layers decreases appreciably from the center towards the shoulder by degrading the rolling resistance of the tire.
- the main objective of the present invention is therefore to distribute the volume of the hoop layer at the shoulder without degrading the endurance of the tire.
- a tire intended to be mounted on a mounting rim of a wheel of a passenger vehicle, the tire having an overall axial width LT mounted on a nominal rim and inflated to a pressure nominal and comprising:
- a crown comprising a tread, intended to come into contact with the ground via a running surface and a crown reinforcement, comprising three layers of reinforcing elements, the tread being radially external to the 'crown frame,
- the crown reinforcement comprising two working layers composed of reinforcing elements parallel to each other forming, with the circumferential direction, an angle between 15 ° and 50 °,
- the crown reinforcement also comprising a hooping layer composed of textile reinforcing elements forming, with the circumferential direction, an angle between 0 ° and 10 °, the hooping layer being radially external to the working layers, and d an axial width LF equal to the axial distance between the two most axially outer points of the hooping reinforcement,
- a carcass reinforcement comprising at least one carcass layer, radially interior at the top and connecting the two beads,
- the hooping layer being constituted by the helical winding of a strip of reinforcing elements whose width LB measured perpendicular to the reinforcing elements is at most equal to 0.09 * LT,
- Each axial distance between the most axially external points of the hooping layer and the most axially external points of each working layer located on the same side of the equator plane being at least equal to 0.38 * LB and at most equal to 1 25 * LB
- the hooping layer being of constant thickness and the axial width LF of the hooping layer being greater than the axial widths of the working layers.
- the overall axial width LT of the tire is measured on a tire mounted on a nominal rim and inflated to a nominal pressure as defined in the regulations.
- the overall axial width LT is defined as the maximum overall flange size in SG service as defined by ETRTO in the document "ETRTO, STANDARDS MANUAL, 2005".
- the hooping layer of constant thickness, has an axial width LF greater than the maximum axial width of the working layers.
- axial width LF is meant the maximum axial distance between the ends on either side of the equator plane of the most axially outer points of the hooping layer on the entire tire. These points can be determined by non-destructive examinations (MRI or other) or by destructive examination by removing the materials radially outside the hoop layer. This involves measuring the axial distance between the most axially outermost points of the corresponding hooping layer at the beginning or end of fitting of the hooping strip. This condition makes it possible to ensure a minimum circumferential rigidity at the ends of the working layers so as to ensure the endurance of the tire at high speed, usually provided by an extra thickness.
- the minimum axial distance between the most axially outer points of the hooping layer on the circumference of the tire and the most axially outer points of the working layers is at least equal to 0.38 * LB in order to ensure a minimum of circumferential stiffness in this area and limit the deformation of the working layers on the shoulders in high speed centrifugation and at most equal to 1.25 * LB, because just as the working layers need the stiffness of the hooping layer at their ends to withstand the extreme stresses of centrifugation, in the same way the hooping layer needs the working layers in this zone there to withstand the stresses linked to the inflation and to the transverse stresses, in the case where no excess thickness of the hooping layer is present on the shoulder area, that is to say, where the thickness of the hooping layer is constant, with variations close to the diameter be reinforcing elements of the hooping layer.
- the hooping layer is of constant thickness means that the hooping layer has substantially the same thickness at each axial point of the hooping layer in each meridian plane.
- the thickness of the hooping layer at an axial point is measured by considering the axially closest reinforcing element of the hooping layer and by measuring the distance between the radially outermost point of the layer of hooping and the radially innermost point of the hooping layer, this distance being measured along a straight line perpendicular to a line passing through the center of all the reinforcing elements of the hooping layer and passing through the center of the element reinforcing the axially closest hooping layer.
- the invention excludes any radial excess thickness of the hooping layer in the axial width of the hooping layer but does not exclude in the center a greater pitch between the turns of the strip of the hooping layer generating gaps or spaces between two reinforcing elements of the hooping layer, in particular around the pla n equatorial.
- the hooping layer is devoid of any double radial winding of the strip.
- the width of the strip for applying the hooping layer measured perpendicular to the elements of reinforcement is limited. Its maximum width must be at most 0.09 * LT. To measure the width LB, it suffices to position itself at the start or end points of laying the hooping layer either by using a suitable non-destructive control means, or by removing the materials radially external to the hooping layer.
- One of the technical means of the invention being to avoid any excess thickness of the hooping layer in the shoulder zone, no excess thickness being necessary in the center of the tire, the latter is of a substantially constant radial thickness over its entire axial width, therefore without dead tower or curling.
- a variant or the pitch of laying of the strip of the hooping layer would be variable over the width, minimum at the shoulders and maximum at the center bringing empty spaces between two radially successive reinforcing elements of the layer hooping, that is to say that the thickness of the hooping layer is substantially constant over its axial width to variations in the diameter of the reinforcing elements.
- the most radially outer point of the tire is distant from the axis of rotation (R) by a radial distance Rm, measured on the equator plane, the tire being mounted on a nominal rim and inflated to a nominal pressure.
- the most radially outer working layer has an axially outermost point, the projection of which is perpendicular to the running surface on the running surface, is at a radial distance Re from the axis of rotation R, Re being measured, the tire being mounted on a nominal rim and inflated to a nominal pressure, and said spray being at a distance d2 from the most axially outer point of the most radially outer working layer.
- d2 is the straight distance between the most axially outside point of the most radially outside working layer in the equator plane, this point being on the radially outside surface SRE of the most radially outer working layer, and projected from this point perpendicular to the running surface on the running surface.
- the nominal pressure is the recommended working pressure.
- Such pressure is for example defined as the basic pressure as defined by ETRTO in the document "ETRTO, STANDARDS MANUAL, 2005".
- the nominal rim is the rim compatible with the use of the tire under normal conditions of use.
- a rim is for example defined as a measuring rim as defined by ETRTO in the document "ETRTO, STANDARDS MAN UAL, 2005".
- d1 of the most radially outer working layer at the most radially outer point of the tire is at least equal to d2 +0.2 * (Rm-Re) .
- d 1, Rm and Re are measured on the equatorial plane of a tire mounted on a nominal rim and inflated to nominal pressure.
- d1 is the straight distance between the most radially outside point of the most radially exterior working layer in the equator plane, this point being on the radially exterior surface SRE of the working layer the most radially outer, and the projected from this point perpendicular to the running surface on the running surface, this projected this being on the equator plane.
- Rm represents the radius of the most radially exterior point, generally located on the equator plane, where is measured d 1, the distance between the running surface and the most radially exterior working layer.
- Re and d2 represent the same characteristics as Rm and d1 but at the axial end of the most radially outer working layer.
- Re represents the radius of the tread surface perpendicular to the axial end of the most radially outer working layer, and d2, the distance between the tread surface and the most radially outer working layer at the same point.
- the condition limits the curvature of the most radially outer working layer over the width of the crown as a function of the variation in the thicknesses of the tread between the shoulder and the center of the tire, slight variations due to the balance of wear and this in order to guarantee that the working layers have the smallest possible variation in radius, a condition made possible by the constant nature of the thickness of the hooping layer, knowing that the hooping layer is present at the places where Rm, Re, d 1, d2 are measured since the axial width of the hooping layer is at least equal to the width of the most radially outer working layer.
- This constancy of the radius facilitates flattening and improves the rolling resistance.
- the tire comprises a rubber compound, said compound for decoupling the carcass from the crown, a rubber compound being radially outside the carcass reinforcement and radially inside the layer of most radially inner work, of which the most axially interior point is axially interior at the most axially exterior point of the most radially interior working layer and whose most axially exterior point of said decoupling compound from the crown carcass, is axially exterior at the most axially exterior point of the hooping reinforcement.
- This allows the ends of the working layers to be kept at a substantially constant radius although the radius of the carcass layer at the shoulder decreases sharply due to the deformation due to inflation.
- the shortest distance (d3) from the most axially outside point of the working layer most radially outside the hooping layer is at least equal to 0.75 times the distance (d4) la shortest from the most axially outside point of the working layer most radially inside the hooping layer and at most equal to 1.25 times the shortest distance (d4) from the most axially outside point of the most working layer radially inside the hooping layer.
- This characteristic associated with the previous one on Re, Rm, d1, d2 ensures that the two working layers both keep a radius as constant as possible in the width of the crown reinforcement.
- d3 is the straight distance between the most axially outer point of the most radially outer working layer, this point being on the radially outer surface SRE of the working layer the most radially outer and projected from this point on the radially inner surface SRI of the hoop layer perpendicular to the radially inner surface SRI of the hoop layer.
- d4 is the straight distance between the most axially outer point of the most radially inner working layer, this point being on the radially outer surface SRE of the most radially inner working layer, and the projection of this point on the radially inner surface SRI of the hooping layer perpendicular to the radially inner surface SRI of the hooping layer.
- the tire according to the invention includes cutouts in the tread overhanging the most axially outer points of the most radially outer working layer, then the shortest distance (d5) from the most radially outer point of the hooping layer overhanging the most axially outer point of the most radially outer working layer at the bottom of said overhanging cutout, is at least equal to 1.5 mm and at most equal to 3 mm, preferably at least equal to 2 mm and at most equal to 2.5 mm.
- This thickness of rubber compound between the bottom surface of the cutouts and the reinforcing elements of the crown reinforcement makes it possible to protect the reinforcing elements of the hooping layer as well as the reinforcing elements of the working layers.
- d5 is the straight distance between the most radially outer point of the hooping layer, point which is located on the radially outer surface SRE of the hooping layer, overhanging the most axially outer point of the most radially outer working layer and the projection of this point on the bottom of the cutout perpendicular to the bottom of the cutout.
- At least two rubber compounds are radially outside the hooping layer and the most radially inner rubber compound is radially inside at the most radially inner points of the cutouts.
- This rubber compound therefore does not have the characteristics of a rubber compound suitable for this use, this makes it possible to use rubber compounds of low resistance to wear or without any particular characteristic with respect to adhesion performance.
- This rubber compound will preferably be chosen for its resistance to attack and its low rolling resistance.
- At least one radially outer rubber compound at the most radially inner points of the cutouts has a dynamic tanô loss, measured according to the same standard ASTM D 5992-96, a temperature of 23 ° C and under a stress of 0.7 MPa at 10 Hz, at most equal to 0.30, preferably at most equal to 0.25.
- the tire preferably comprises cutouts in the tread and their maximum depth when new in the tread is at least equal to 5 mm and at most equal at 8 mm, preferably at least equal to 6 mm and at most equal to 7 mm.
- the reinforcing elements of at least one working layer is advantageous for the reinforcing elements of at least one working layer to be constituted by unitary metallic wires or monofilaments having a section of which the smallest dimension is at most equal to 0.40 mm, preferably at most equal to 0.30 mm.
- this type of reinforcing element makes it possible to reduce the thickness of the working reinforcement and therefore to limit the hysteresis of the materials which constitute it.
- At least one rubber compound in contact with the reinforcing elements of the working layers has a dynamic tanô loss, measured according to the same standard ASTM D 5992 - 96, a temperature of 23 ° C and under a stress of 0.7 MPa at 10 Hz, at most equal to 0.20, preferably at most equal to 0.15.
- the transverse grooves axially external to the points located at an axial distance at most equal to 0.3 * LT from the equator plane P have a width at most equal to 2 mm.
- the shoulder zone in order to have effective grip on wet ground, it is preferable for the shoulder zone to include grooves and in particular transverse grooves for discharging water from the contact surface of the tire with the rolling ground.
- the grooves have a width at least equal to 3 mm. This arrangement relaxes the tread and increases the rolling resistance.
- Another possibility is to increase the number of transverse grooves by limiting their width to 2 mm. During the crushing, the lateral surfaces of the grooves come to bear on one another thus limiting the flexibility of the tread and therefore its rolling resistance.
- transverse groove is meant all the grooves making an angle with the axial direction of between -75 ° and 75 °.
- the carcass reinforcement consists of a single textile carcass layer, preferably of polyethylene terephthalate type, aliphatic polyamide, combination of aliphatic polyamide and aromatic polyamide, or combination of polyterephthalate d ethylene and aromatic polyamide.
- the reinforcing elements of the hooping layer are textile reinforcing elements, preferably of the aliphatic polyamide, aromatic polyamide, combination of aliphatic polyamide and aromatic polyamide, polyethylene terephthalate or rayon type. .
- FIG. 1 is a part of a tire, in particular its architecture and its tread provided with transverse grooves and circumferential grooves.
- Figure 2 very schematically shows the widest working layer 41 and the hooping layer 5 unwound.
- Figure 3 shows a meridian section of the top of a tire according to the invention and illustrates the different radial distances, Rm, Re, d1 and the distance d2.
- FIG. 4 represents a view of details of the shoulder zone of a meridian section of the summit to illustrate the distances d3, d4 and d5 and the rubbery stuffing compound 7.
- FIG. 1 represents a perspective view of part of the crown of a tire.
- Each Cartesian plane is associated with a Cartesian coordinate system (XX ’, YY’, ZZ ’).
- the tire comprises a tread 2 intended to come into contact with a ground via a tread surface 21.
- grooves 25 of width W are arranged possibly different from a groove with the other. These grooves 25 can be transverse grooves or circumferential grooves.
- the tire also comprises a carcass reinforcement 6 and a crown reinforcement 3 comprising a working reinforcement 4 and a hooping reinforcement 5.
- the working reinforcement comprises two working layers 41 and 42 each comprising parallel reinforcing elements between them.
- FIG. 2 very schematically shows the working layers 41 and 42 of respective width L41 and L42 and the hoop layer 5 "unrolled" to explain the principle of sizes, L41, L42, LF.
- the axial width LF is the overall width of the hooping layer between the most axially outer points of the hooping layer 512 and 51 1 which represent the beginnings or ends of laying the strip of reinforcing elements of the hooping layer 5.
- the width LB represents the width of the strip for applying the hooping layer. LB is easily measurable at the start or end points of the hooping layer.
- L41 represents the axial width of the working layer 41 and L42 represents the axial width of the working layer 42. These widths are substantially constant over the circumference of the tire to within the manufacturing variations and can be measured on a meridian cut.
- the tire has axial distances D1, DT, D2, D2 'between the most axially outer points 51 1, 512 of the hooping layer 5 and the points 411, 412, 421 , 422 the most axially outermost of each working layer 41, 42 located on the same axial side of the equator plane P.
- D1, DT, D2, D2 ' between the most axially outer points 51 1, 512 of the hooping layer 5 and the points 411, 412, 421 , 422 the most axially outermost of each working layer 41, 42 located on the same axial side of the equator plane P.
- the axial distance D1 separates the most axially external point 512 of the hooping layer 5 and the most axially external point 412 of the working layer 41 situated on the same left side of the equator plane P in FIG. 2,
- the axial distance DT separates the most axially outward point 51 1 from the hooping layer 5 and the most axially outward point 41 1 from the working layer 41 situated on the same right side of the equator plane P in FIG. 2,
- the axial distance D2 separates the most axially external point 512 of the hooping layer 5 and the most axially external point 422 of the working layer 42 situated on the same left side of the equator plane P in FIG. 2,
- FIG. 3 schematically represents the meridian half-section of the top of the tire according to the invention.
- FIG. 3 illustrates in particular the most axially exterior points of the working layers 41, 42, respectively the points 411 and 421, the most axially exterior point 51 1 of the hooping layer 5, the most axially exterior point 71 of the compound rubbery 7 for decoupling the carcass layer 6 and the hooping layer 5.
- the projection perpendicular to the running surface, on the running surface of point 421 is point 212.
- FIG. 2 also illustrates the following distances:
- Rm radial distance from the axis of rotation of the tire to its most radially outer point 211, measured on the equator plane, the tire being mounted on a nominal rim and inflated to nominal pressure.
- the distance d1 radial distance measured on the equator plane between the most radially exterior point of the tire 211 and the most radially exterior points of the most radially exterior working layer 42. • Re: radial distance from the axis of rotation of the tire at point 212 projected perpendicularly to the running surface, on the running surface of point 421 most axially outside of the most radially outside working layer 42.
- FIG. 4 represents a detail view of a meridian section of the shoulder zone to illustrate the distances d3, d4 and d5 and the rubbery stuffing compound 7:
- D3 is the shortest distance from the most axially outer point 421 of the working layer 42 to the hooping layer 5,
- D4 is the shortest distance from point 41 1 most axially outside of the working layer 41 to the hooping layer 5,
- • d5 is the shortest distance from the most radially outside point of the hooping layer 5 overhanging from the most axially outside point 421 of the most radially outside working layer 42 to the most radially inside point of the cutouts 25, c that is to say at the bottom of the cutout 25 materialized by a dotted line in FIG. 4.
- a meridian section of the tire is obtained by cutting the tire along two meridian planes. This section is used to determine the different radial distances, the center of the bottom faces of the transverse grooves and the circumferential grooves.
- the invention was carried out on a tire A of size 205/55 R16 intended to equip a passenger vehicle.
- the depths of the carvings are between 5 mm at the shoulders and 7 mm at the equator.
- the crown reinforcement is composed of two working layers, the reinforcement elements of which form an angle of + or - 25 ° with the circumferential direction, and a textile hooping layer of which the reinforcement elements form an angle of + or - 3 ° with the circumferential direction.
- the invention A is compared with tires B and C.
- B according to the state of the art is identical to A but the hooping layer of the tire B is not of constant thickness and the width LF of the layer of hooping of tire B is weaker and has an additional turn on the shoulder area.
- the tire C is identical to the tire B but with a constant thickness of the hooping layer, namely without additional revolution of the hooping strip in the shoulder area and the same width LF of the hooping layer as the tire B.
- the tires have an overall width LT equal to 215 mm, measured on the tire inflated to 2.5 bars on a 6.5J16 rim.
- the axial width of the hooping layer is 174 mm for tires B and C and 190 mm for tire A according to the invention.
- the width LB of the application strip, measurable at the start and end points of application of the hooping layer is 10.2 mm for tires A, B and C so that the condition LB at most equal to 0.09 * LT is respected.
- the tire A according to the invention and the tire C have a thickness of the hooping layer constant and equal to 0.84 mm for a thickness of the reinforcing elements of the hooping layer equal to 0.66 mm.
- the tire B according to the state of the art has a thickness of the hooping layer varying from 1.7 mm at the shoulder, due to a dead turn of the hooping layer, for a thickness at the equatorial plane equal to 0.84 mm for reinforcing elements having a thickness equal to 0.66 mm.
- the axial widths of the working layers L41 and L42 are 178 mm and 164 mm respectively. Therefore for the tire A according to the invention, the axial width of the hooping layer is greater than each axial width of each working layer 41, 42.
- Each axial distance D1, DT, D2, D2 'between the points 511, 512 the most axially outermost of the hooping layer 5 on the circumference of the tire and the most axially outermost points 411, 412, 421, 422 of each working layer 41, 42 situated on the same axial side of the equator plane P as each point 51 1, 512 is at least equal to 0.38 * LB (4.56 mm) and at most equal to 1.25 * LB (15 mm) making it possible to comply with the related design conditions for the lower bound for uniformity and resistance to centrifugation at high speed and for the endurance of the shrinking layer.
- the tire B has a mass greater than that of the tire A.
- A, B and D have the same maximum radius Rm, equal to 316.8 mm and the same shoulder radius Re because the same mold profile at 309 mm and the same depth HSC of sculpture.
- the tires A and B have a distance d2 equal to 8 mm while the tire D has a distance d2 equal to 7 mm.
- the elimination of the excess thickness of the hooping layer in the shoulder area of the tire D relative to the tire B makes it possible to reduce the distance d2 for the tire D according to the invention to 7 mm as against 8 mm for the tire B while retaining the same tread thickness simply by removing a thickness of hooping layer whose thickness is 0.84 mm.
- the tire D thus achieves the same performance as the tires A and B in limit speed and uniformity but has an improved rolling resistance performance of 0.2 Kg / t.
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Abstract
Disclosed is a pneumatic tire (1) which has an overall axial width LT and a maximum diameter Rm, and the tread (2) of which has an axial width L and comprises two working plies (41, 42) and a reinforcement ply (5). The reinforcement ply (5) is formed by helically winding a strip of reinforcing elements, the width LB of which, measured perpendicularly to the reinforcing elements, is at most 0.09*LT and which has a constant thickness excluding any extra thickness of the reinforcement ply, but without excluding possible discontinuities. The axial width LF of the reinforcement ply (5) is greater than the axial width (L41, L42) of the working plies (41, 42). The minimum axial distance between the axially outermost points (511, 512) of the reinforcement ply and the crown plies is at least 0.38*LB and at most 1.25*LB.
Description
Pneumatique à architecture sommet optimisée Tires with optimized crown architecture
[0001] DOMAINE DE L’INVENTION FIELD OF THE INVENTION
[0002] La présente invention concerne un pneumatique destiné à être monté sur un véhicule de tourisme, et plus particulièrement le sommet d’un tel pneumatique. The present invention relates to a tire intended to be mounted on a passenger vehicle, and more particularly the top of such a tire.
[0003] Un pneumatique ayant une géométrie de révolution par rapport à un axe de rotation, la géométrie du pneumatique est généralement décrite dans un plan méridien contenant l’axe de rotation du pneumatique. Pour un plan méridien donné, les directions radiale, axiale et circonférentielle désignent respectivement les directions perpendiculaire à l’axe de rotation du pneumatique, parallèle à l’axe de rotation du pneumatique et perpendiculaire au plan méridien. Le plan circonférentiel médian dit plan équateur divise le pneumatique en deux demi tores sensiblement symétriques, le pneumatique pouvant présenter des dissymétries de bande de roulement, d’architecture, liées à la précision de fabrication ou au dimensionnement. [0003] A tire having a geometry of revolution relative to an axis of rotation, the geometry of the tire is generally described in a meridian plane containing the axis of rotation of the tire. For a given meridian plane, the radial, axial and circumferential directions respectively designate the directions perpendicular to the axis of rotation of the tire, parallel to the axis of rotation of the tire and perpendicular to the meridian plane. The median circumferential plane, called the equator plane, divides the tire into two substantially symmetrical half toroids, the tire possibly having asymmetries in tread, in architecture, linked to manufacturing precision or to sizing.
[0004] Dans ce qui suit, les expressions « radialement intérieur à» et « radialement extérieur à» signifient respectivement « plus proche de l’axe de rotation du pneumatique, selon la direction radiale, que » et « plus éloigné de l’axe de rotation du pneumatique, selon la direction radiale, que ». Les expressions « axialement intérieur à» et « axialement extérieur à» signifient respectivement « plus proche du plan équateur, selon la direction axiale, que » et « plus éloigné du plan équateur, selon la direction axiale, que ». Une « distance radiale » est une distance par rapport à l’axe de rotation du pneumatique, et une « distance axiale » est une distance par rapport au plan équateur du pneumatique. Une « épaisseur radiale » est mesurée selon la direction radiale, et une « largeur axiale » est mesurée selon la direction axiale. In what follows, the expressions "radially inside" and "radially outside" mean respectively "closer to the axis of rotation of the tire, in the radial direction, than" and "further from the axis of rotation of the tire, in the radial direction, that ". The expressions "axially inside of" and "axially outside of" mean respectively "closer to the equator plane, in the axial direction, than" and "further away from the equator plane, in the axial direction, than". A "radial distance" is a distance from the axis of rotation of the tire, and an "axial distance" is a distance from the equatorial plane of the tire. A "radial thickness" is measured in the radial direction, and an "axial width" is measured in the axial direction.
[0005] Un pneumatique comprend un sommet comprenant une bande roulement destinée à venir en contact avec le sol par l’intermédiaire d’une surface de roulement, deux bourrelets destinés à venir en contact avec une jante et deux flancs reliant le sommet aux bourrelets. En outre, un pneumatique comprend une armature de carcasse comprenant au moins une couche de carcasse, radialement intérieure au sommet et reliant les deux bourrelets. A tire comprises a crown comprising a tread intended to come into contact with the ground by means of a running surface, two beads intended to come into contact with a rim and two sidewalls connecting the crown to the beads. In addition, a tire comprises a carcass reinforcement comprising at least one carcass layer, radially interior at the top and connecting the two beads.
[0006] La bande de roulement est en outre constituée par un ou plusieurs mélanges ou composés caoutchouteux. Les expressions « mélange caoutchouteux » ou « composé caoutchouteux » désigne une composition de caoutchouc comportant au moins un élastomère et une charge. The tread is further formed by one or more mixtures or rubber compounds. The expressions “rubber mixture” or “rubber compound” designates a rubber composition comprising at least one elastomer and a filler.
[0007] Le sommet comprend au moins une armature de sommet radialement intérieure à la bande de roulement. L’armature de sommet comprend au moins une armature de
travail comprenant au moins une couche de travail composée d’éléments de renforcement parallèles entre eux formant, avec la direction circonférentielle, un angle compris entre 15° et 50°. L’invention est relative aux pneumatiques dont l’armature de sommet comprend une armature de frettage comprenant au moins une couche de frettage composée d’éléments de renforcement formant, avec la direction circonférentielle, un angle compris entre 0° et 10°, l’armature de frettage étant le plus souvent mais pas obligatoirement radialement extérieure aux couches de travail. The crown comprises at least one crown reinforcement radially inside the tread. The crown reinforcement comprises at least one reinforcement of work comprising at least one working layer composed of reinforcing elements parallel to each other forming, with the circumferential direction, an angle between 15 ° and 50 °. The invention relates to tires, the crown reinforcement of which comprises a hooping reinforcement comprising at least one hooping layer composed of reinforcing elements forming, with the circumferential direction, an angle between 0 ° and 10 °, the hooping reinforcement being most often but not necessarily radially external to the working layers.
[0008] Pour toute couche d’éléments de renforcement d’armature de sommet, de travail, ou autre, une surface continue, dite surface radialement extérieure (SRE) de la dite couche, passe par le point le plus radialement extérieur de chaque élément de renforcement, de chaque méridien. Pour toute couche d’éléments de renforcement d’armature de sommet, de travail, ou autre, une surface continue, dite surface radialement intérieure (SRI) de la dite couche, passe par les points le plus radialement intérieur de chaque élément de renforcement, de chaque méridien. Les distances radiales entre une couche d’éléments de renforcement et tout autre point, sont mesurées depuis l’une ou l’autre de ces surfaces et de manière à ne pas intégrer l’épaisseur radiale de la dite couche. Si l’autre point de mesure est radialement extérieur à la couche d’éléments de renforcement, la distance radiale est mesurée depuis la surface radialement extérieure SRE à ce point, et respectivement depuis la surface radialement intérieure SRI à l’autre point de mesure si celui-ci est radialement intérieur à la couche d’éléments de renforcement. Ceci permet de prendre des distances radiales cohérentes d’un méridien à l’autre, sans avoir à tenir compte des variations locales possibles liées aux formes des sections des éléments de renforcement des couches. For any layer of crown reinforcement elements, working, or other, a continuous surface, said radially outer surface (SRE) of said layer, passes through the most radially outer point of each element of reinforcement, of each meridian. For any layer of reinforcement elements of crown reinforcement, of work, or other, a continuous surface, called radially inner surface (SRI) of said layer, passes through the most radially inner points of each reinforcement element, of each meridian. The radial distances between a layer of reinforcing elements and any other point, are measured from one or the other of these surfaces and so as not to integrate the radial thickness of said layer. If the other measurement point is radially outside the layer of reinforcing elements, the radial distance is measured from the radially exterior surface SRE at this point, and respectively from the radially interior surface SRI at the other measurement point if this is radially inside the layer of reinforcing elements. This makes it possible to take coherent radial distances from one meridian to another, without having to take into account the possible local variations linked to the shapes of the sections of the reinforcing elements of the layers.
[0009] Afin d’obtenir des performances en adhérence sur sol mouillé, des découpures sont disposées dans la bande de roulement. Une découpure désigne soit un puits, soit une rainure, soit une incision, soit un sillon circonférentiel et forme un espace débouchant sur la surface de roulement et délimitée radialement intérieurement par un fond de découpure. In order to obtain wet grip performance, cutouts are placed in the tread. A cutout designates either a well, a groove, an incision, or a circumferential groove and forms a space opening onto the rolling surface and delimited radially internally by a cutout bottom.
[0010] Une incision ou une rainure présente, sur la surface de roulement, deux dimensions principales caractéristiques : une largeur W et une longueur Lo, telle que la longueur Lo est au moins égale à 2 fois la largeur W. Une incision ou une rainure est donc délimitée par au moins deux faces latérales principales déterminant sa longueur Lo et reliées par une face de fond, les deux faces latérales principales étant distantes l’une de l’autre d’une distance non nulle, dite largeur W de l’incision ou de la rainure.
[0011] La profondeur d’une découpure est la distance maximale entre la surface de roulement et le fond de la découpure. Cette distance maximale étant mesurée selon une direction orthogonale à la fois à la surface de roulement et à la fois au fond de la découpure. An incision or a groove has, on the running surface, two main characteristic dimensions: a width W and a length Lo, such that the length Lo is at least equal to twice the width W. An incision or a groove is therefore delimited by at least two main lateral faces determining its length Lo and connected by a bottom face, the two main lateral faces being distant from each other by a non-zero distance, called width W of the incision or the groove. The depth of a cutout is the maximum distance between the running surface and the bottom of the cutout. This maximum distance being measured in a direction orthogonal both to the rolling surface and to the bottom of the cut.
[0012] Dans ce qui suit, l’expression « en surplomb de » signifie, « pour chaque méridien, radialement extérieur dans la limite des coordonnées axiales délimitées par ». Ainsi « les points les plus radialement extérieurs de la couche de frettage en surplomb des points les plus axialement extérieurs de la couche de travail la plus radialement extérieure » désignent pour chaque méridien, l’ensemble des points les plus radialement extérieurs de la couche de frettage radialement extérieurs aux points les plus axialement extérieurs de la couche de travail la plus radialement extérieure, dans la limite des coordonnées axiales de ces derniers. In what follows, the expression "overhanging" means, "for each meridian, radially exterior within the limit of the axial coordinates delimited by". Thus "the most radially outer points of the hooping layer overhanging the most axially outer points of the most radially outer working layer" denote for each meridian, the set of the most radially outer points of the hooping layer radially exterior to the most axially exterior points of the most radially exterior working layer, within the limit of the axial coordinates of the latter.
[0013] ETAT DE LA TECHNIQUE STATE OF THE ART
[0014] Un pneumatique doit répondre à de multiples critères de performance portant sur des phénomènes comme l’endurance, l’uniformité, la résistance au roulement. Pour répondre à des performances d’endurance à haute vitesse, un grand nombre de pneumatiques sont dotés de couche de frettage. Ces couches de frettage ont une très grande rigidité en extension dans la direction circonférentielle et permettent de reprendre les efforts de centrifugation à grande vitesse. Pour améliorer la productivité, la couche de frettage est posée en bandelette de plusieurs fils d’une largeur LB mesurées perpendiculairement aux éléments de renforcement de ladite bandelette. Plus la bandelette est large moins sa pose nécessite de tours et donc de temps de fabrication pour aller d’une manière continue depuis une des extrémités axiales de l’armature de sommet à l’autre. La difficulté est que plus la bandelette de la couche de frettage est large plus les effets de bords sont importants car la largeur depuis l’extrémité axiale de la couche de frettage au plan équateur varie au tour de roue de la largeur de la bandelette de pose. Cette variation a une influence sur l’uniformité des pneumatiques et leur endurance à haute vitesse. A tire must meet multiple performance criteria relating to phenomena such as endurance, uniformity, rolling resistance. To meet endurance performance at high speed, a large number of tires are fitted with a hoop layer. These hooping layers have a very high rigidity in extension in the circumferential direction and allow the centrifugal forces to be taken up at high speed. To improve productivity, the hooping layer is placed in a strip of several wires of a width LB measured perpendicular to the reinforcing elements of said strip. The wider the strip, the less turns it takes and therefore the manufacturing time to go continuously from one of the axial ends of the crown reinforcement to the other. The difficulty is that the wider the strip of the hooping layer, the greater the edge effects because the width from the axial end of the hooping layer to the equatorial plane varies around the wheel from the width of the laying strip. . This variation has an influence on the uniformity of tires and their endurance at high speed.
[0015] Pour résoudre ce problème, les fabricants de pneumatique ont imaginé de nombreuses solutions. Certains commencent par un ou plusieurs tours, à 0° dits tours morts, de la bandelette de frettage sur la zone la plus axialement extérieure des couches de travail ou épaule du pneumatique, comme par exemple dans JP2016/066809, pour générer des surépaisseurs de couche de frettage par tuilage de la couche de frettage dans la zone épaule.
[0016] Cependant l’impact de ces solutions sur les autres performances n’est pas négligeable car cette surépaisseur de la couche de frettage se trouve dans une zone ou le volume des matériaux caoutchouteux ou des éléments de renforcement, est contraint entre la couche de carcasse dont le dimensionnement est déterminé par la courbe d’équilibre sous pression et le profil de la bande de roulement déterminé par l’équilibre entre l’usure de la zone centrale de la bande de roulement et l’usure de la zone épaule. To solve this problem, tire manufacturers have devised many solutions. Some begin with one or more turns, at 0 ° so-called dead turns, of the hooping strip on the most axially outer zone of the working layers or shoulder of the tire, as for example in JP2016 / 066809, to generate layer thicknesses hooping of the hooping layer in the shoulder area. However, the impact of these solutions on the other performances is not negligible because this extra thickness of the hooping layer is located in an area where the volume of the rubbery materials or the reinforcing elements is constrained between the layer of carcass, the dimensioning of which is determined by the pressure equilibrium curve and the tread profile determined by the balance between wear and tear in the central area of the tread and wear and tear in the shoulder area.
[0017] Pour une résistance au roulement optimisée, les couches de travail doivent avoir un rayon sensiblement constant entre le centre et les épaules du pneumatique, ce qui facilite la mise à plat. La surépaisseur d’un tour mort de la bandelette de la couche de frettage, est plus proche de la surface de roulement que la couche de frettage au centre un pneumatique, et pourrait être agressé lors d’un roulage sur un objet présent sur le sol de roulage. De plus cette surépaisseur diminue le volume de la bande de roulement sur la zone épaule. Les pneumatiques ainsi conçus arrivent en limite d’usage dans plus de 80% des cas avec les zones épaule en limite d’usure et une zone centrale pouvant encore faire plusieurs milliers de kilomètres. For optimized rolling resistance, the working layers must have a substantially constant radius between the center and the shoulders of the tire, which facilitates flattening. The extra thickness of a dead turn of the band of the hooping layer is closer to the rolling surface than the hooping layer in the center of a tire, and could be attacked when rolling over an object on the ground. of rolling. In addition, this extra thickness reduces the volume of the tread on the shoulder area. The tires thus designed arrive at the wear limit in more than 80% of the cases with the shoulder zones at the wear limit and a central zone that can still cover several thousand kilometers.
[0018] La solution utilisée dans l’état de l’art est donc de concevoir le pneumatique tel que le rayon des couches de travail diminue sensiblement du centre vers l’épaule en dégradant la résistance au roulement du pneumatique. The solution used in the state of the art is therefore to design the tire such that the radius of the working layers decreases appreciably from the center towards the shoulder by degrading the rolling resistance of the tire.
[0019] RESUME DE L’INVENTION SUMMARY OF THE INVENTION
[0020] L’objectif principal de la présente invention est donc de répartir le volume de la couche de frettage à l’épaule sans dégrader l’endurance du pneumatique The main objective of the present invention is therefore to distribute the volume of the hoop layer at the shoulder without degrading the endurance of the tire.
[0021] Cet objectif est atteint par un pneumatique, destiné à être monté sur une jante de montage d’une roue d’un véhicule de tourisme, le pneumatique ayant une largeur axiale hors tout LT monté sur une jante nominale et gonflé à une pression nominale et comportant : This objective is achieved by a tire, intended to be mounted on a mounting rim of a wheel of a passenger vehicle, the tire having an overall axial width LT mounted on a nominal rim and inflated to a pressure nominal and comprising:
• un axe de rotation (R), un plan équateur (P) qui est le plan circonférentiel passant par le centre de gravité du pneumatique et perpendiculaire à l’axe de rotation (R), An axis of rotation (R), an equator plane (P) which is the circumferential plane passing through the center of gravity of the tire and perpendicular to the axis of rotation (R),
• un sommet comprenant une bande roulement, destinée à venir en contact avec le sol par l’intermédiaire d’une surface de roulement et une armature de sommet, comprenant trois couches d’éléments de renforcement, la bande de roulement étant radialement extérieure à l’armature de sommet, • a crown comprising a tread, intended to come into contact with the ground via a running surface and a crown reinforcement, comprising three layers of reinforcing elements, the tread being radially external to the 'crown frame,
• l’armature de sommet comprenant deux couches de travail composée d’éléments de renforcement parallèles entre eux formant, avec la direction circonférentielle, un angle compris entre 15° et 50°,
• l’armature de sommet comprenant également une couche de frettage composée d’éléments de renforcement textile formant, avec la direction circonférentielle, un angle compris entre 0° et 10°, la couche de frettage étant radialement extérieure aux couches de travail, et d’une largeur axiale LF égale à la distance axiale entre les deux points les plus axialement extérieurs de l’armature de frettage, The crown reinforcement comprising two working layers composed of reinforcing elements parallel to each other forming, with the circumferential direction, an angle between 15 ° and 50 °, The crown reinforcement also comprising a hooping layer composed of textile reinforcing elements forming, with the circumferential direction, an angle between 0 ° and 10 °, the hooping layer being radially external to the working layers, and d an axial width LF equal to the axial distance between the two most axially outer points of the hooping reinforcement,
• deux bourrelets destinés à venir en contact avec une jante et deux flancs reliant le sommet aux bourrelets, • two beads intended to come into contact with a rim and two sides connecting the top to the beads,
• une armature de carcasse comprenant au moins une couche de carcasse, radialement intérieure au sommet et reliant les deux bourrelets, A carcass reinforcement comprising at least one carcass layer, radially interior at the top and connecting the two beads,
• la couche de frettage étant constituée par l’enroulement hélicoïdal d’une bandelette d’éléments de renforcement dont la largeur LB mesurée perpendiculairement aux éléments de renforcement est au plus égale à 0.09*LT, The hooping layer being constituted by the helical winding of a strip of reinforcing elements whose width LB measured perpendicular to the reinforcing elements is at most equal to 0.09 * LT,
• chaque distance axiale entre les points les plus axialement extérieurs de la couche de frettage et les points les plus axialement extérieurs de chaque couche de travail situés d’un même côté du plan équateur étant au moins égale à 0.38*LB et au plus égale à 1 25*LB Each axial distance between the most axially external points of the hooping layer and the most axially external points of each working layer located on the same side of the equator plane being at least equal to 0.38 * LB and at most equal to 1 25 * LB
• la couche de frettage étant d’épaisseur constante et la largeur axiale LF de la couche de frettage étant supérieure aux largeurs axiales des couches de travail. • the hooping layer being of constant thickness and the axial width LF of the hooping layer being greater than the axial widths of the working layers.
[0022] La largeur axiale hors tout LT du pneumatique est mesurée sur un pneumatique monté sur une jante nominale et gonflé à une pression nominale tel que définie dans les règlements. Par exemple, la largeur axiale hors tout LT est définie comme la Grosseur Boudin Hors Tout maximum en service SG telle que définie par l’ETRTO dans le document « ETRTO, STANDARDS MANUAL, 2005 ». The overall axial width LT of the tire is measured on a tire mounted on a nominal rim and inflated to a nominal pressure as defined in the regulations. For example, the overall axial width LT is defined as the maximum overall flange size in SG service as defined by ETRTO in the document "ETRTO, STANDARDS MANUAL, 2005".
[0023] Pour assurer une uniformité et une endurance correctes au pneumatique, il est essentiel que la couche de frettage, d’épaisseur constante, ait une largeur axiale LF supérieure à la largeur axiale maximale des couches de travail. Par largeur axiale LF, on entend la distance axiale maximale entre les extrémités de part et d’autres du plan équateur des points les plus axialement extérieurs de la couche de frettage sur la totalité du pneumatique. Ces points peuvent être déterminés par des examens non destructifs (IRM ou autre) ou par examen destructif en enlevant les matériaux radialement extérieurs à la couche de frettage. Il s’agit de mesurer la distance axiale entre les points les plus axialement extérieurs de la couche de frettage correspondant
au début ou fin de pose de la bandelette de frettage. Cette condition permet d’assurer une rigidité minimale circonférentielle aux extrémités des couches de travail de manière à assurer l’endurance du pneumatique à haute vitesse, habituellement assurée par une surépaisseur. To ensure correct uniformity and endurance for the tire, it is essential that the hooping layer, of constant thickness, has an axial width LF greater than the maximum axial width of the working layers. By axial width LF is meant the maximum axial distance between the ends on either side of the equator plane of the most axially outer points of the hooping layer on the entire tire. These points can be determined by non-destructive examinations (MRI or other) or by destructive examination by removing the materials radially outside the hoop layer. This involves measuring the axial distance between the most axially outermost points of the corresponding hooping layer at the beginning or end of fitting of the hooping strip. This condition makes it possible to ensure a minimum circumferential rigidity at the ends of the working layers so as to ensure the endurance of the tire at high speed, usually provided by an extra thickness.
[0024] La distance axiale minimale entre les points les plus axialement extérieurs de la couche de frettage sur la circonférence du pneumatique et les points les plus axialement extérieurs des couches de travail est au moins égale à 0.38*LB afin d’assurer un minimum de rigidité circonférentielle dans cette zone et limiter la déformation des couche de travail aux épaules en centrifugation à haute vitesse et au plus égale à 1.25*LB, car de même que les couches de travail ont besoin de la rigidité de la couche de frettage à leurs extrémités pour résister aux sollicitations extrêmes de centrifugation, de même la couche de frettage a besoin des couches de travail dans cette zone là pour supporter les sollicitations liées au gonflage et aux sollicitations transverses, dans le cas où aucune surépaisseur de la couche de frettage n’est présente sur la zone épaule, c’est-à-dire, où l’épaisseur de la couche de frettage est constante, aux variations près du diamètre des éléments de renforcement de la couche de frettage. The minimum axial distance between the most axially outer points of the hooping layer on the circumference of the tire and the most axially outer points of the working layers is at least equal to 0.38 * LB in order to ensure a minimum of circumferential stiffness in this area and limit the deformation of the working layers on the shoulders in high speed centrifugation and at most equal to 1.25 * LB, because just as the working layers need the stiffness of the hooping layer at their ends to withstand the extreme stresses of centrifugation, in the same way the hooping layer needs the working layers in this zone there to withstand the stresses linked to the inflation and to the transverse stresses, in the case where no excess thickness of the hooping layer is present on the shoulder area, that is to say, where the thickness of the hooping layer is constant, with variations close to the diameter be reinforcing elements of the hooping layer.
[0025] La couche de frettage est d’épaisseur constante signifie que la couche de frettage présente sensiblement la même épaisseur en chaque point axial de la couche de frettage dans chaque plan méridien. Dans chaque plan méridien, l’épaisseur de la couche de frettage en un point axial est mesurée en considérant l’élément de renforcement de la couche de frettage axialement le plus proche et en mesurant la distance entre le point radialement le plus extérieur de la couche de frettage et le point radialement le plus intérieur de la couche de frettage, cette distance étant mesurée selon une droite perpendiculaire à une ligne passant par le centre de tous les éléments de renforcement de la couche de frettage et passant par le centre de l’élément de renforcement de la couche de frettage axialement le plus proche.. Ainsi l’invention exclut toute surépaisseur radiale de la couche de frettage dans la largeur axiale de la couche de frettage mais n’exclut pas au centre un pas plus grand entre les tours de la bandelette de la couche de frettage générant des interstices ou des espaces entre deux éléments de renforcement de la couche de frettage, notamment autour du plan équatorial. Ainsi, la couche de frettage est dépourvue de tout double enroulement radial de la bandelette. The hooping layer is of constant thickness means that the hooping layer has substantially the same thickness at each axial point of the hooping layer in each meridian plane. In each meridian plane, the thickness of the hooping layer at an axial point is measured by considering the axially closest reinforcing element of the hooping layer and by measuring the distance between the radially outermost point of the layer of hooping and the radially innermost point of the hooping layer, this distance being measured along a straight line perpendicular to a line passing through the center of all the reinforcing elements of the hooping layer and passing through the center of the element reinforcing the axially closest hooping layer. Thus the invention excludes any radial excess thickness of the hooping layer in the axial width of the hooping layer but does not exclude in the center a greater pitch between the turns of the strip of the hooping layer generating gaps or spaces between two reinforcing elements of the hooping layer, in particular around the pla n equatorial. Thus, the hooping layer is devoid of any double radial winding of the strip.
[0026] Pour une raison identique il est indispensable que la largeur de la bandelette de pose de la couche de frettage, mesurée perpendiculairement aux éléments de
renforcement soit limitée. Sa largeur maximale doit être au plus égale à 0.09*LT. Pour mesurer la largeur LB, il suffit de se placer aux points de début ou fin de pose de la couche de frettage soit en utilisant un moyen de contrôle non destructif apte, soit en enlevant les matériaux radialement extérieurs à la couche de frettage. For the same reason it is essential that the width of the strip for applying the hooping layer, measured perpendicular to the elements of reinforcement is limited. Its maximum width must be at most 0.09 * LT. To measure the width LB, it suffices to position itself at the start or end points of laying the hooping layer either by using a suitable non-destructive control means, or by removing the materials radially external to the hooping layer.
[0027] Un des moyens techniques de l’invention étant d’éviter toute surépaisseur de la couche de frettage dans la zone épaule, aucune surépaisseur n’étant nécessaire au centre du pneumatique, celle-ci est d’une épaisseur radiale sensiblement constante sur toute sa largeur axiale, donc sans tour mort, ni tuilage. En revanche est inclus dans l’invention une variante ou le pas de pose de la bandelette de la couche de frettage serait variable sur la largeur, minimal aux épaules et maximal au centre amenant des espaces vides entre deux éléments de renforcement radialement successifs de la couche de frettage, c’est-à-dire que l’épaisseur de la couche de frettage est sensiblement constante sur sa largeur axiale aux variations du diamètre des éléments de renforcement près. One of the technical means of the invention being to avoid any excess thickness of the hooping layer in the shoulder zone, no excess thickness being necessary in the center of the tire, the latter is of a substantially constant radial thickness over its entire axial width, therefore without dead tower or curling. On the other hand is included in the invention a variant or the pitch of laying of the strip of the hooping layer would be variable over the width, minimum at the shoulders and maximum at the center bringing empty spaces between two radially successive reinforcing elements of the layer hooping, that is to say that the thickness of the hooping layer is substantially constant over its axial width to variations in the diameter of the reinforcing elements.
[0028] On notera que, dans un mode de réalisation, le point le plus radialement extérieur du pneumatique est distant de l’axe de rotation (R) d’une distance radiale Rm, mesurée sur le plan équateur, le pneumatique étant monté sur une jante nominale et gonflé à une pression nominale. It will be noted that, in one embodiment, the most radially outer point of the tire is distant from the axis of rotation (R) by a radial distance Rm, measured on the equator plane, the tire being mounted on a nominal rim and inflated to a nominal pressure.
[0029] On notera également que dans un mode de réalisation, la couche de travail la plus radialement extérieure a un point le plus axialement extérieur dont le projeté perpendiculairement à la surface de roulement sur la surface de roulement, est à une distance radiale Re de l’axe de rotation R, Re étant mesurée le pneumatique étant monté sur une jante nominale et gonflé à une pression nominale, et ledit projeté étant à une distance d2 du point le plus axialement extérieur de la couche de travail la plus radialement extérieure. En d’autres termes, dans ce mode de réalisation, d2 est la distance droite entre le point le plus axialement à l’extérieur de la couche de travail la plus radialement extérieure dans le plan équateur, ce point se trouvant sur la surface radialement extérieure SRE de la couche de travail la plus radialement extérieure, et le projeté de ce point perpendiculairement à la surface de roulement sur la surface de roulement. It will also be noted that in one embodiment, the most radially outer working layer has an axially outermost point, the projection of which is perpendicular to the running surface on the running surface, is at a radial distance Re from the axis of rotation R, Re being measured, the tire being mounted on a nominal rim and inflated to a nominal pressure, and said spray being at a distance d2 from the most axially outer point of the most radially outer working layer. In other words, in this embodiment, d2 is the straight distance between the most axially outside point of the most radially outside working layer in the equator plane, this point being on the radially outside surface SRE of the most radially outer working layer, and projected from this point perpendicular to the running surface on the running surface.
[0030] La pression nominale est la pression d’utilisation recommandée. Une telle pression est par exemple définie comme la pression de base telle que définie par l’ETRTO dans le document « ETRTO, STANDARDS MANUAL, 2005 ». The nominal pressure is the recommended working pressure. Such pressure is for example defined as the basic pressure as defined by ETRTO in the document "ETRTO, STANDARDS MANUAL, 2005".
[0031] La jante nominale est la jante compatible avec l'utilisation du pneumatique dans des conditions normales d’utilisation. Une telle jante est par exemple définie comme
une jante de mesure telle que définie par l’ETRTO dans le document « ETRTO, STANDARDS MAN UAL, 2005 ». The nominal rim is the rim compatible with the use of the tire under normal conditions of use. Such a rim is for example defined as a measuring rim as defined by ETRTO in the document "ETRTO, STANDARDS MAN UAL, 2005".
[0032] Un des modes préférés de l’invention est que la distance radiale d1 de la couche de travail la plus radialement extérieure au point le plus radialement extérieur du pneumatique est au moins égale à d2 +0,2*(Rm-Re). d 1 , Rm et Re sont mesurées sur le plan équateur d’un pneumatique monté sur une jante nominale et gonflé à la pression nominale. En d’autres termes, d1 est la distance droite entre le point le plus radialement à l’extérieur de la couche de travail la plus radialement extérieure dans le plan équateur, ce point se trouvant sur la surface radialement extérieure SRE de la couche de travail la plus radialement extérieure, et le projeté de ce point perpendiculairement à la surface de roulement sur la surface de roulement, ce projeté ce trouvant sur le plan équateur. One of the preferred modes of the invention is that the radial distance d1 of the most radially outer working layer at the most radially outer point of the tire is at least equal to d2 +0.2 * (Rm-Re) . d 1, Rm and Re are measured on the equatorial plane of a tire mounted on a nominal rim and inflated to nominal pressure. In other words, d1 is the straight distance between the most radially outside point of the most radially exterior working layer in the equator plane, this point being on the radially exterior surface SRE of the working layer the most radially outer, and the projected from this point perpendicular to the running surface on the running surface, this projected this being on the equator plane.
[0033] Rm représente le rayon du point le plus radialement extérieur, généralement situé sur le plan équateur, là où est mesuré d 1 , la distance entre la surface de roulement et la couche de travail la plus radialement extérieure. Re et d2 représente les mêmes caractéristiques que Rm et d1 mais au niveau de l’extrémité axiale de la couche de travail la plus radialement extérieure. Rm represents the radius of the most radially exterior point, generally located on the equator plane, where is measured d 1, the distance between the running surface and the most radially exterior working layer. Re and d2 represent the same characteristics as Rm and d1 but at the axial end of the most radially outer working layer.
[0034] Re représente le rayon de la surface de roulement à l’aplomb de l’extrémité axiale de la couche de travail la plus radialement extérieure, et d2, la distance entre la surface de roulement et la couche de travail la plus radialement extérieure au même point. La condition limite la courbure de la couche de travail la plus radialement extérieure sur la largeur du sommet en fonction de la variation des épaisseurs de la bande de roulement entre l’épaule et le centre du pneumatique, variations faibles en raison de l’équilibre de l’usure et ce afin de garantir que les couches de travail ont une variation de rayon la plus limitée possible, condition rendue possible par le caractère constant de l’épaisseur de la couche de frettage, sachant que la couche de frettage est présente aux endroits où Rm, Re, d 1 , d2 sont mesurés puisque la largeur axiale de la couche de frettage est au moins égale à la largeur de la couche de travail la plus radialement extérieure. Re represents the radius of the tread surface perpendicular to the axial end of the most radially outer working layer, and d2, the distance between the tread surface and the most radially outer working layer at the same point. The condition limits the curvature of the most radially outer working layer over the width of the crown as a function of the variation in the thicknesses of the tread between the shoulder and the center of the tire, slight variations due to the balance of wear and this in order to guarantee that the working layers have the smallest possible variation in radius, a condition made possible by the constant nature of the thickness of the hooping layer, knowing that the hooping layer is present at the places where Rm, Re, d 1, d2 are measured since the axial width of the hooping layer is at least equal to the width of the most radially outer working layer.
[0035] Cette constance du rayon facilite la mise à plat et améliore la résistance au roulement. This constancy of the radius facilitates flattening and improves the rolling resistance.
[0036] Pour améliorer encore cette mise à plat, il est avantageux que le pneumatique comprenne un composé caoutchouteux, dit composé de découplage de la carcasse du sommet, composé caoutchouteux étant radialement extérieur à l’armature de carcasse et radialement intérieur à la couche de travail la plus radialement intérieure, dont le
point le plus axialement intérieur est axialement intérieur au point le plus axialement extérieur de la couche de travail la plus radialement intérieure et dont le point le plus axialement extérieur dudit composé de découplage de la carcasse du sommet, est axialement extérieur au point le plus axialement extérieur de l’armature de frettage. Cela permet de conserver les extrémités des couches de travail à un rayon sensiblement constant bien que le rayon de la couche de carcasse à l’épaule décroisse fortement en raison de la déformation due au gonflage. To further improve this flattening, it is advantageous for the tire to comprise a rubber compound, said compound for decoupling the carcass from the crown, a rubber compound being radially outside the carcass reinforcement and radially inside the layer of most radially inner work, of which the most axially interior point is axially interior at the most axially exterior point of the most radially interior working layer and whose most axially exterior point of said decoupling compound from the crown carcass, is axially exterior at the most axially exterior point of the hooping reinforcement. This allows the ends of the working layers to be kept at a substantially constant radius although the radius of the carcass layer at the shoulder decreases sharply due to the deformation due to inflation.
[0037] Une solution préférée est que la distance (d3) la plus courte du point le plus axialement extérieur de la couche de travail la plus radialement extérieure à la couche de frettage, est au moins égale à 0.75 fois la distance (d4) la plus courte du point le plus axialement extérieur de la couche de travail la plus radialement intérieure à la couche de frettage et au plus égale à 1.25 fois la distance (d4) la plus courte du point le plus axialement extérieur de la couche de travail la plus radialement intérieure à la couche de frettage. Cette caractéristique associée à la précédente sur Re, Rm, d1 , d2, assure que les deux couches de travail gardent l’une et l’autre un rayon aussi constant que possible dans la largeur de l’armature de sommet. A preferred solution is that the shortest distance (d3) from the most axially outside point of the working layer most radially outside the hooping layer, is at least equal to 0.75 times the distance (d4) la shortest from the most axially outside point of the working layer most radially inside the hooping layer and at most equal to 1.25 times the shortest distance (d4) from the most axially outside point of the most working layer radially inside the hooping layer. This characteristic associated with the previous one on Re, Rm, d1, d2, ensures that the two working layers both keep a radius as constant as possible in the width of the crown reinforcement.
[0038] En d’autres termes, dans cette solution, d3 est la distance droite entre le point le plus axialement extérieur de la couche de travail la plus radialement extérieure, ce point se trouvant sur la surface radialement extérieure SRE de la couche de travail la plus radialement extérieure et le projeté de ce point sur la surface radialement intérieure SRI de la couche de frettage perpendiculairement à la surface radialement intérieure SRI de la couche de frettage. Egalement en d’autres termes, d4 est la distance droite entre le point le plus axialement extérieur de la couche de travail la plus radialement intérieure, ce point se trouvant sur la surface radialement extérieure SRE de la couche de travail la plus radialement intérieure, et le projeté de ce point sur la surface radialement intérieure SRI de la couche de frettage perpendiculairement à la surface radialement intérieure SRI de la couche de frettage. In other words, in this solution, d3 is the straight distance between the most axially outer point of the most radially outer working layer, this point being on the radially outer surface SRE of the working layer the most radially outer and projected from this point on the radially inner surface SRI of the hoop layer perpendicular to the radially inner surface SRI of the hoop layer. Also in other words, d4 is the straight distance between the most axially outer point of the most radially inner working layer, this point being on the radially outer surface SRE of the most radially inner working layer, and the projection of this point on the radially inner surface SRI of the hooping layer perpendicular to the radially inner surface SRI of the hooping layer.
[0039] Afin de garantir une bonne endurance aux agressions de la bande de roulement lors du roulage en cas de présence d’obstacles sur le sol de roulage, il est préféré que, lorsque le pneumatique selon l’invention, comprend des découpures dans la bande de roulement en surplomb des points les plus axialement extérieurs de la couche de travail la plus radialement extérieure, alors la distance (d5) la plus courte du point le plus radialement extérieur de la couche de frettage en surplomb du point le plus axialement extérieur de la couche de travail la plus radialement extérieure au fond de la dite découpure en surplomb, est au moins égale à 1.5 mm et au plus égale à 3 mm,
préférentiellement au moins égale à 2 mm et au plus égale à 2.5 mm. Cette épaisseur de composé caoutchouteux entre la surface de fond des découpures et les éléments de renforcement de l’armature de sommet permet de protéger les éléments de renforcement de la couche de frettage ainsi que les éléments de renforcement des couches de travail. In order to guarantee good endurance to attacks from the tread during driving in the presence of obstacles on the road surface, it is preferred that, when the tire according to the invention, includes cutouts in the tread overhanging the most axially outer points of the most radially outer working layer, then the shortest distance (d5) from the most radially outer point of the hooping layer overhanging the most axially outer point of the most radially outer working layer at the bottom of said overhanging cutout, is at least equal to 1.5 mm and at most equal to 3 mm, preferably at least equal to 2 mm and at most equal to 2.5 mm. This thickness of rubber compound between the bottom surface of the cutouts and the reinforcing elements of the crown reinforcement makes it possible to protect the reinforcing elements of the hooping layer as well as the reinforcing elements of the working layers.
[0040] En d’autres termes, dans ce mode de réalisation préféré, d5 est la distance droite entre le point le plus radialement extérieur de la couche de frettage, point qui se situe sur la surface radialement extérieure SRE de la couche de frettage, en surplomb du point le plus axialement extérieur de la couche de travail la plus radialement extérieure et le projeté de ce point sur le fond de la découpure perpendiculairement au fond de la découpure. In other words, in this preferred embodiment, d5 is the straight distance between the most radially outer point of the hooping layer, point which is located on the radially outer surface SRE of the hooping layer, overhanging the most axially outer point of the most radially outer working layer and the projection of this point on the bottom of the cutout perpendicular to the bottom of the cutout.
[0041] Il est avantageux qu’au moins deux composés caoutchouteux soient radialement extérieurs à la couche de frettage et le composé caoutchouteux le plus radialement intérieur est radialement intérieur aux points les plus radialement intérieurs des découpures. Le fait que le composé caoutchouteux le plus radialement intérieur soit intérieur aux surfaces de fonds des découpures implique que ce composé caoutchouteux n’est pas destiné à toucher le sol. Ce composé caoutchouteux n’a donc pas les caractéristiques d’un composé caoutchouteux apte à cet usage, cela permet d’utiliser des composés caoutchouteux de faible résistance à l’usure ou sans caractéristique particulières vis à vis des performances en adhérence. Ce composé caoutchouteux sera choisi préférentiellement pour sa résistance aux agressions et sa faible résistance au roulement. It is advantageous that at least two rubber compounds are radially outside the hooping layer and the most radially inner rubber compound is radially inside at the most radially inner points of the cutouts. The fact that the most radially inner rubber compound is internal to the bottom surfaces of the cutouts implies that this rubber compound is not intended to touch the ground. This rubber compound therefore does not have the characteristics of a rubber compound suitable for this use, this makes it possible to use rubber compounds of low resistance to wear or without any particular characteristic with respect to adhesion performance. This rubber compound will preferably be chosen for its resistance to attack and its low rolling resistance.
[0042] Pour diminuer la résistance au roulement du pneumatique, il est préféré qu’au moins un composé caoutchouteux radialement extérieur aux points les plus radialement intérieurs des découpures ait une perte dynamique tanô, mesurée selon la même norme ASTM D 5992 - 96, à une température de 23°C et sous une contrainte de 0,7 MPa à 10 Hz, au plus égale à 0.30, préférentiellement au plus égale à 0.25. To reduce the rolling resistance of the tire, it is preferred that at least one radially outer rubber compound at the most radially inner points of the cutouts has a dynamic tanô loss, measured according to the same standard ASTM D 5992-96, a temperature of 23 ° C and under a stress of 0.7 MPa at 10 Hz, at most equal to 0.30, preferably at most equal to 0.25.
[0043] L’invention étant destiné à un pneumatique de tourisme, le pneumatique comprend préférentiellement des découpures dans la bande de roulement et leur profondeur maximale à l’état neuf dans la bande de roulement est au moins égale à 5 mm et au plus égale à 8 mm, préférentiellement au moins égale à 6 mm et au plus égale à 7 mm. The invention being intended for a passenger tire, the tire preferably comprises cutouts in the tread and their maximum depth when new in the tread is at least equal to 5 mm and at most equal at 8 mm, preferably at least equal to 6 mm and at most equal to 7 mm.
[0044] Pour optimiser la résistance au roulement, il est avantageux que les éléments de renforcement d’au moins une couche de travail soient constitués par des fils métalliques unitaires ou monofilaments ayant une section dont la plus petite dimension
est au plus égale à 0.40 mm, préférentiellement au plus égale à 0.30 mm. En effet ce type d’éléments de renforcement permet de diminuer l’épaisseur de l’armature de travail et donc de limiter l’hystérèse des matériaux qui la constituent. To optimize the rolling resistance, it is advantageous for the reinforcing elements of at least one working layer to be constituted by unitary metallic wires or monofilaments having a section of which the smallest dimension is at most equal to 0.40 mm, preferably at most equal to 0.30 mm. In fact, this type of reinforcing element makes it possible to reduce the thickness of the working reinforcement and therefore to limit the hysteresis of the materials which constitute it.
[0045] Pour un pneumatique optimisé en résistance au roulement, il est avantageux qu’au moins un composé caoutchouteux au contact des éléments de renforcement des couches de travail ait une perte dynamique tanô, mesurée selon la même norme ASTM D 5992 - 96, à une température de 23°C et sous une contrainte de 0,7 MPa à 10 Hz, au plus égale à 0.20, préférentiellement au plus égal à 0.15. For a tire optimized for rolling resistance, it is advantageous that at least one rubber compound in contact with the reinforcing elements of the working layers has a dynamic tanô loss, measured according to the same standard ASTM D 5992 - 96, a temperature of 23 ° C and under a stress of 0.7 MPa at 10 Hz, at most equal to 0.20, preferably at most equal to 0.15.
[0046] Il est avantageux que les rainures transversales axialement extérieures aux points situés à une distance axiale au plus égale à 0.3*LT du plan équateur P, ont une largeur au plus égale à 2 mm. En effet pour avoir une adhérence sur sol mouillé performante, il est préférable que la zone épaule comprenne des rainures et notamment des rainures transversales pour évacuer l’eau de la surface de contact du pneumatique avec le sol de roulage. Usuellement les rainures ont une largeur au moins égale à 3 mm. Cette disposition assoupli la bande de roulement et augmente la résistance au roulement. Une autre possibilité est d’augmenter le nombre de rainures transversales en limitant leur largeur à 2 mm. Lors de l’écrasement, les surfaces latérales des rainures viennent prendre appui les unes sur les autres limitant ainsi la souplesse de la bande de roulement et donc sa résistance au roulement. Par rainure transversale, on entend toutes les rainures faisant un angle avec la direction axiale compris entre -75° et 75°. It is advantageous that the transverse grooves axially external to the points located at an axial distance at most equal to 0.3 * LT from the equator plane P, have a width at most equal to 2 mm. In fact, in order to have effective grip on wet ground, it is preferable for the shoulder zone to include grooves and in particular transverse grooves for discharging water from the contact surface of the tire with the rolling ground. Usually the grooves have a width at least equal to 3 mm. This arrangement relaxes the tread and increases the rolling resistance. Another possibility is to increase the number of transverse grooves by limiting their width to 2 mm. During the crushing, the lateral surfaces of the grooves come to bear on one another thus limiting the flexibility of the tread and therefore its rolling resistance. By transverse groove is meant all the grooves making an angle with the axial direction of between -75 ° and 75 °.
[0047] Il est avantageux que l’armature de carcasse soit constituée d’une unique couche de carcasse en textile, de préférence de type polytéréphtalate d'éthylène, polyamide aliphatique, combinaison de polyamide aliphatique et de polyamide aromatique, ou combinaison de polytéréphtalate d'éthylène et de polyamide aromatique. En limitant le nombre de couche de carcasse on limite également l’hystérèse des matériaux de ces couches et on limite ainsi la résistance au roulement du pneumatique. It is advantageous that the carcass reinforcement consists of a single textile carcass layer, preferably of polyethylene terephthalate type, aliphatic polyamide, combination of aliphatic polyamide and aromatic polyamide, or combination of polyterephthalate d ethylene and aromatic polyamide. By limiting the number of carcass layers, the hysteresis of the materials in these layers is also limited, thereby limiting the rolling resistance of the tire.
[0048] Une solution préférée est que les éléments de renforcement de la couche de frettage soient des éléments de renforcement en textile, de préférence de type polyamide aliphatique, polyamide aromatique, combinaison de polyamide aliphatique et de polyamide aromatique, polytéréphtalate d'éthylène ou rayonne. A preferred solution is that the reinforcing elements of the hooping layer are textile reinforcing elements, preferably of the aliphatic polyamide, aromatic polyamide, combination of aliphatic polyamide and aromatic polyamide, polyethylene terephthalate or rayon type. .
[0049] BREVE DESCRIPTION DES DESSINS
[0050] Les caractéristiques et autres avantages de l’invention seront mieux compris à l’aide des figures 1 à 4, les dites figures n’étant pas représentées à l’échelle mais de façon simplifiée, afin de faciliter la compréhension de l’invention : BRIEF DESCRIPTION OF THE DRAWINGS The characteristics and other advantages of the invention will be better understood using Figures 1 to 4, said figures not being shown to scale but in a simplified manner, in order to facilitate understanding of the invention:
• La figure 1 est une partie de pneumatique, en particulier son architecture et sa bande de roulement pourvue de rainures transversales et de sillons circonférentiels. FIG. 1 is a part of a tire, in particular its architecture and its tread provided with transverse grooves and circumferential grooves.
• la figure 2 représente très schématiquement la couche de travail de largeur la plus large 41 et la couche de frettage 5 déroulée. • Figure 2 very schematically shows the widest working layer 41 and the hooping layer 5 unwound.
• la figure 3 représente une coupe méridienne du sommet d’un pneumatique selon l’invention et illustre les différentes distances radiales, Rm, Re, d1 et la distance d2. • Figure 3 shows a meridian section of the top of a tire according to the invention and illustrates the different radial distances, Rm, Re, d1 and the distance d2.
• la figure 4 représente une vue de détails de la zone épaule d’une coupe méridienne du sommet pour illustrer les distances d3, d4 et d5 et le composé caoutchouteux de bourrage 7. FIG. 4 represents a view of details of the shoulder zone of a meridian section of the summit to illustrate the distances d3, d4 and d5 and the rubbery stuffing compound 7.
[0051 ] DESCRIPTION DETAILLEE DES DESSINS DETAILED DESCRIPTION OF THE DRAWINGS
[0052] La figure 1 représente une vue en perspective d’une partie du sommet d’un pneumatique. A chaque plan méridien est associé un repère cartésien (XX’, YY’, ZZ’). Le pneumatique comporte une bande de roulement 2 destinée à entrer en contact avec un sol par l’intermédiaire d’une surface de roulement 21. Dans la bande de roulement 2, sont disposées des rainures 25 de largeur W possiblement différentes d’une rainure à l’autre. Ces rainures 25 peuvent être des rainures transversales ou des sillons circonférentiels. Le pneumatique comprend en outre une armature de carcasse 6 et une armature de sommet 3 comprenant une armature de travail 4 et une armature de frettage 5. L’armature de travail comprend deux couches de travail 41 et 42 comprenant chacune des éléments de renforcement parallèles entre eux. FIG. 1 represents a perspective view of part of the crown of a tire. Each Cartesian plane is associated with a Cartesian coordinate system (XX ’, YY’, ZZ ’). The tire comprises a tread 2 intended to come into contact with a ground via a tread surface 21. In the tread 2, grooves 25 of width W are arranged possibly different from a groove with the other. These grooves 25 can be transverse grooves or circumferential grooves. The tire also comprises a carcass reinforcement 6 and a crown reinforcement 3 comprising a working reinforcement 4 and a hooping reinforcement 5. The working reinforcement comprises two working layers 41 and 42 each comprising parallel reinforcing elements between them.
[0053] La figure 2 représente très schématiquement les couches de travail 41 et 42 de largeur respectives L41 et L42 et la couche de frettage 5 « déroulée » pour expliquer le principe des grandeurs, L41 , L42, LF. La largeur axiale LF est la largeur hors-tout le la couche de frettage entre les points les plus axialement extérieurs de la couche de frettage 512 et 51 1 qui représentent des débuts ou des fins de pose de la bandelette d’éléments de renforcement de la couche de frettage 5. La largeur LB représente la largeur de la bandelette de pose de la couche de frettage. LB est facilement mesurable sur les points de départ ou de fins de pose de la couche de frettage. L41 représente la largeur axiale de la couche de travail 41 et L42 la largeur axiale de la couche de travail
42. Ces largeurs sont sensiblement constantes sur la circonférence du pneumatique aux variations de fabrication près et sont mesurables sur une coupe méridienne. Figure 2 very schematically shows the working layers 41 and 42 of respective width L41 and L42 and the hoop layer 5 "unrolled" to explain the principle of sizes, L41, L42, LF. The axial width LF is the overall width of the hooping layer between the most axially outer points of the hooping layer 512 and 51 1 which represent the beginnings or ends of laying the strip of reinforcing elements of the hooping layer 5. The width LB represents the width of the strip for applying the hooping layer. LB is easily measurable at the start or end points of the hooping layer. L41 represents the axial width of the working layer 41 and L42 represents the axial width of the working layer 42. These widths are substantially constant over the circumference of the tire to within the manufacturing variations and can be measured on a meridian cut.
[0054] Toujours en référence à la figure 2, le pneumatique présente des distances axiales D1 , DT, D2, D2’ entre les points 51 1 , 512 les plus axialement extérieurs de la couche de frettage 5 et les points 411 , 412, 421 , 422 les plus axialement extérieurs de chaque couche de travail 41 , 42 situés d’un même côté axial du plan équateur P. En l’espèce : Still with reference to FIG. 2, the tire has axial distances D1, DT, D2, D2 'between the most axially outer points 51 1, 512 of the hooping layer 5 and the points 411, 412, 421 , 422 the most axially outermost of each working layer 41, 42 located on the same axial side of the equator plane P. In the present case:
- la distance axiale D1 sépare le point 512 le plus axialement extérieur de la couche de frettage 5 et le point 412 le plus axialement extérieur de la couche de travail 41 situé du même côté gauche du plan équateur P sur la figure 2, the axial distance D1 separates the most axially external point 512 of the hooping layer 5 and the most axially external point 412 of the working layer 41 situated on the same left side of the equator plane P in FIG. 2,
- la distance axiale DT sépare le point 51 1 le plus axialement extérieur de la couche de frettage 5 et le point 41 1 le plus axialement extérieur de la couche de travail 41 situé du même côté droit du plan équateur P sur la figure 2, the axial distance DT separates the most axially outward point 51 1 from the hooping layer 5 and the most axially outward point 41 1 from the working layer 41 situated on the same right side of the equator plane P in FIG. 2,
- la distance axiale D2 sépare le point 512 le plus axialement extérieur de la couche de frettage 5 et le point 422 le plus axialement extérieur de la couche de travail 42 situé du même côté gauche du plan équateur P sur la figure 2, the axial distance D2 separates the most axially external point 512 of the hooping layer 5 and the most axially external point 422 of the working layer 42 situated on the same left side of the equator plane P in FIG. 2,
- la distance axiale D1’ sépare le point 511 le plus axialement extérieur de la couche de frettage 5 et le point 421 le plus axialement extérieur de la couche de travail 42 situé du même côté droit du plan équateur P sur la figure 2. - the axial distance D1 ’separates the most axially outer point 511 of the hoop layer 5 and the most axially outer point 421 of the working layer 42 located on the same right side of the equator plane P in FIG. 2.
[0055] Ici, on a D1 =DT et D2=D2’. Here, we have D1 = DT and D2 = D2 ’.
[0056] La figure 3 représente schématiquement la demi-coupe méridienne du sommet du pneumatique selon l’invention. La figure 3 illustre notamment les points les plus axialement extérieurs des couches de travail 41 , 42, respectivement les points 411 et 421 , le point le plus axialement extérieur 51 1 de la couche de frettage 5, le point le plus axialement extérieur 71 du composé caoutchouteux 7 de découplage de la couche de carcasse 6 et de la couche de frettage 5. Le projeté perpendiculairement à la surface de roulement, sur la surface de roulement du point 421 est le point 212. La figure 2 illustre également les distances suivantes : FIG. 3 schematically represents the meridian half-section of the top of the tire according to the invention. FIG. 3 illustrates in particular the most axially exterior points of the working layers 41, 42, respectively the points 411 and 421, the most axially exterior point 51 1 of the hooping layer 5, the most axially exterior point 71 of the compound rubbery 7 for decoupling the carcass layer 6 and the hooping layer 5. The projection perpendicular to the running surface, on the running surface of point 421 is point 212. FIG. 2 also illustrates the following distances:
• Rm : distance radiale de l’axe de rotation du pneumatique à son point le plus radialement extérieur 211 , mesurée sur le plan équateur le pneumatique étant monté sur une jante nominale et gonflé à la pression nominale. • Rm: radial distance from the axis of rotation of the tire to its most radially outer point 211, measured on the equator plane, the tire being mounted on a nominal rim and inflated to nominal pressure.
• La distance d1 : distance radiale mesurée sur le plan équateur entre le point le plus radialement extérieur du pneumatique 211 et les points les plus radialement extérieurs de la couche de travail la plus radialement extérieure 42.
• Re : distance radiale de l’axe de rotation du pneumatique au point 212 projeté perpendiculairement à la surface de roulement, sur la surface de roulement du point 421 le plus axialement extérieur de la couche de travail la plus radialement extérieure 42. The distance d1: radial distance measured on the equator plane between the most radially exterior point of the tire 211 and the most radially exterior points of the most radially exterior working layer 42. • Re: radial distance from the axis of rotation of the tire at point 212 projected perpendicularly to the running surface, on the running surface of point 421 most axially outside of the most radially outside working layer 42.
• La distance d2 entre le point 421 le plus axialement extérieur de la couche de travail la plus radialement extérieure 42 et le point 212 projeté perpendiculairement à la surface de roulement 21 , sur la surface de roulement 21 du point 421 le plus axialement extérieur de la couche de travail la plus radialement extérieure 42. The distance d2 between the most axially outer point 421 of the most radially outer working layer 42 and the point 212 projected perpendicularly to the rolling surface 21, on the rolling surface 21 of the most axially outer point 421 of the most radially outer working layer 42.
[0057] La profondeur d’un sillon circonférentiel HSC. Dans le cas où plusieurs sillons circonférentiels sont présents, HSC représente la profondeur du sillon le plus profond. La figure 4 représente une vue de détails d’une coupe méridienne de la zone épaule pour illustrer les distances d3, d4 et d5 et le composé caoutchouteux de bourrage 7 : The depth of an HSC circumferential groove. In the case where several circumferential grooves are present, HSC represents the depth of the deepest groove. FIG. 4 represents a detail view of a meridian section of the shoulder zone to illustrate the distances d3, d4 and d5 and the rubbery stuffing compound 7:
• d3 est la distance la plus courte du point 421 le plus axialement extérieur de la couche de travail 42 à la couche de frettage 5, D3 is the shortest distance from the most axially outer point 421 of the working layer 42 to the hooping layer 5,
• d4 est la distance la plus courte du point 41 1 le plus axialement extérieur de la couche de travail 41 à la couche de frettage 5, D4 is the shortest distance from point 41 1 most axially outside of the working layer 41 to the hooping layer 5,
• d5 est la distance la plus courte du point le plus radialement extérieur de la couche de frettage 5 en surplomb du point le plus axialement extérieur 421 de la couche de travail la plus radialement extérieure 42 au point le plus radialement intérieur des découpures 25, c’est-à-dire au fond de la découpure 25 matérialisé par une ligne pointillée sur la figure 4. • d5 is the shortest distance from the most radially outside point of the hooping layer 5 overhanging from the most axially outside point 421 of the most radially outside working layer 42 to the most radially inside point of the cutouts 25, c that is to say at the bottom of the cutout 25 materialized by a dotted line in FIG. 4.
[0058] Une coupe méridienne du pneumatique est obtenue par découpage du pneumatique selon deux plans méridiens. Cette coupe sert à déterminer les différentes distances radiales, le centre des faces de fond des rainures transversales et des sillons circonférentiels. A meridian section of the tire is obtained by cutting the tire along two meridian planes. This section is used to determine the different radial distances, the center of the bottom faces of the transverse grooves and the circumferential grooves.
[0059] L’invention a été réalisée sur un pneumatique A de dimension 205/55 R16 destiné à équiper un véhicule de tourisme. Les profondeurs des découpures de la sculpture sont comprises entre 5 mm aux épaules et 7 mm à l’équateur. L’armature sommet est composée de deux couches de travail dont les éléments de renforcement font un angle de + ou - 25° avec la direction circonférentielle et d’une couche de frettage textile dont les éléments de renforcement font un angle de + ou - 3° avec la direction circonférentielle. L’invention A est comparée à des pneumatiques B et C. B suivant l’état de l’art est identique à A mais la couche de frettage du pneumatique B n’est pas d’épaisseur constante et la largeur LF de la couche de frettage du
pneumatique B est plus faible et présente un tour supplémentaire sur la zone épaule. Le pneumatique C, est identique au pneumatique B mais avec une épaisseur de la couche de frettage constante à savoir sans tour supplémentaire de la bandelette de frettage dans la zone épaule et la même largeur LF de la couche de frettage que le pneumatique B. The invention was carried out on a tire A of size 205/55 R16 intended to equip a passenger vehicle. The depths of the carvings are between 5 mm at the shoulders and 7 mm at the equator. The crown reinforcement is composed of two working layers, the reinforcement elements of which form an angle of + or - 25 ° with the circumferential direction, and a textile hooping layer of which the reinforcement elements form an angle of + or - 3 ° with the circumferential direction. The invention A is compared with tires B and C. B according to the state of the art is identical to A but the hooping layer of the tire B is not of constant thickness and the width LF of the layer of hooping of tire B is weaker and has an additional turn on the shoulder area. The tire C is identical to the tire B but with a constant thickness of the hooping layer, namely without additional revolution of the hooping strip in the shoulder area and the same width LF of the hooping layer as the tire B.
[0060] Les pneumatiques ont une largeur hors tout LT égale à 215 mm, mesurée sur le pneumatique gonflé à 2,5 bars sur une jante 6.5J16. La largeur axiale de la couche de frettage est de 174 mm pour les pneumatiques B et C et de 190 mm pour le pneumatique A selon l’invention. La largeur LB de la bandelette de pose, mesurable aux points de début et de fin de pose de la couche de frettage est de 10.2 mm pour les pneumatiques A, B et C de sorte que la condition LB au plus égale à 0.09*LT est respectée. Le pneumatique A selon l’invention et le pneumatique C ont une épaisseur de la couche de frettage constante et égale à 0.84 mm pour une épaisseur des éléments de renforcement de la couche de frettage égale à 0.66 mm. Le pneumatique B selon l’état de l’art a une épaisseur de la couche de frettage variant de 1.7 mm à l’épaule, due à un tour mort de la couche de frettage, pour une épaisseur au niveau du plan équateur égale à 0.84 mm pour des éléments de renforcement ayant une épaisseur égale à 0.66 mm. Les largeurs axiales des couches de travail L41 et L42 sont respectivement de 178 mm et 164 mm. Donc pour le pneumatique A selon l’invention, la largeur axiale de la couche de frettage est supérieure à chaque largeur axiale de chaque couche de travail 41 , 42. Chaque distance axiale D1 , DT, D2, D2’ entre les points 511 , 512 les plus axialement extérieurs de la couche de frettage 5 sur la circonférence du pneumatique et les points les plus axialement extérieurs 411 , 412, 421 , 422 de chaque couche de travail 41 , 42 situés d’un même côté axial du plan équateur P que chaque point 51 1 , 512 est au moins égale à 0.38*LB (4.56 mm) et au plus égale à 1.25*LB (15 mm) permettant de respecter les conditions de dimensionnement liées pour la borne inférieure à l’uniformité et la résistance à la centrifugation à haute vitesse et pour l’endurance de la couche de frettage. En l’espèce, D1 =D1’=6 mm et D2=D2’=13 mm. The tires have an overall width LT equal to 215 mm, measured on the tire inflated to 2.5 bars on a 6.5J16 rim. The axial width of the hooping layer is 174 mm for tires B and C and 190 mm for tire A according to the invention. The width LB of the application strip, measurable at the start and end points of application of the hooping layer is 10.2 mm for tires A, B and C so that the condition LB at most equal to 0.09 * LT is respected. The tire A according to the invention and the tire C have a thickness of the hooping layer constant and equal to 0.84 mm for a thickness of the reinforcing elements of the hooping layer equal to 0.66 mm. The tire B according to the state of the art has a thickness of the hooping layer varying from 1.7 mm at the shoulder, due to a dead turn of the hooping layer, for a thickness at the equatorial plane equal to 0.84 mm for reinforcing elements having a thickness equal to 0.66 mm. The axial widths of the working layers L41 and L42 are 178 mm and 164 mm respectively. Therefore for the tire A according to the invention, the axial width of the hooping layer is greater than each axial width of each working layer 41, 42. Each axial distance D1, DT, D2, D2 'between the points 511, 512 the most axially outermost of the hooping layer 5 on the circumference of the tire and the most axially outermost points 411, 412, 421, 422 of each working layer 41, 42 situated on the same axial side of the equator plane P as each point 51 1, 512 is at least equal to 0.38 * LB (4.56 mm) and at most equal to 1.25 * LB (15 mm) making it possible to comply with the related design conditions for the lower bound for uniformity and resistance to centrifugation at high speed and for the endurance of the shrinking layer. In this case, D1 = D1 '= 6 mm and D2 = D2' = 13 mm.
[0061] L’absence de la surépaisseur de la couche de frettage dans le pneumatique selon la solution C et le non-respect des conditions de l’invention amène à une diminution de la vitesse limite de 20 km/h. Les tests de vitesse limite sont bien connus de l’homme de l’art et exigés de la part des constructeurs d’automobiles. Ces tests consistent à faire rouler le pneumatique sur un volant métallique à une charge et une pression donnée par le constructeur et à faire des paliers de 20 mn à une vitesse
donnée, augmentant par paliers, jusqu’à la défaillance du pneumatique. Les pneumatiques A et B atteignent les mêmes niveaux de performance en vitesse limite et en uniformité. The absence of the excess thickness of the hooping layer in the tire according to solution C and the non-compliance with the conditions of the invention leads to a reduction in the speed limit of 20 km / h. Speed limit tests are well known to those of skill in the art and are required of automobile manufacturers. These tests consist of rolling the tire on a metal flywheel at a load and a pressure given by the manufacturer and making 20-minute steps at a speed given, increasing in stages, until the tire fails. Tires A and B achieve the same performance levels in speed limit and uniformity.
[0062] Néanmoins, de par la présence d’un tour supplémentaire sur la zone épaule, le pneumatique B présente une masse supérieure à celle du pneumatique A. However, due to the presence of an additional turn on the shoulder area, the tire B has a mass greater than that of the tire A.
L’absence d’une surépaisseur de la couche de frettage dans la zone épaule du pneumatique selon l’invention permet également d’augmenter le taux de creux dans cette zone pour améliorer l’adhérence sur sol humide mais aussi de remonter les couches de travail vis-à-vis du pneumatique témoin ce qui facilite la mise à plat et permet d’améliorer la résistance au roulement du pneumatique. The absence of an additional thickness of the hooping layer in the shoulder area of the tire according to the invention also makes it possible to increase the rate of recess in this area to improve the grip on wet ground but also to raise the working layers. vis-à-vis the control tire which facilitates flattening and improves the rolling resistance of the tire.
[0063] Ainsi, on pourra envisager de modifier le pneumatique A pour fabriquer un pneumatique D présentant une performance améliorée en résistance au roulement. A, B et D ont les mêmes rayons maximal Rm, égal à 316.8 mm et le même rayon épaule Re car le même profil moule à 309 mm et la même profondeur HSC de sculpture. Les pneumatiques A et B présentent une distance d2 égale à 8 mm alors que le pneumatique D présente une distance d2 égale à 7 mm. La suppression de la surépaisseur de la couche de frettage dans la zone épaule du pneumatique D par rapport au pneumatique B permet de diminuer la distance d2 pour le pneumatique D selon l’invention à 7 mm contre 8 mm pour le pneumatique B en conservant la même épaisseur de bande de roulement simplement en supprimant une épaisseur de couche de frettage dont l’épaisseur est de 0.84 mm. En outre, le pneumatique D respecte les conditions suivantes: d1 =9,45 mm est au moins égale à d2+0.2(Rm-Re)=8.7 mm quand le pneumatique B ne les respecte pas : d1 =9.45 mm et d2+0.2(Rm-Re)=9.68 mm. Thus, one can consider modifying the tire A to manufacture a tire D having improved performance in rolling resistance. A, B and D have the same maximum radius Rm, equal to 316.8 mm and the same shoulder radius Re because the same mold profile at 309 mm and the same depth HSC of sculpture. The tires A and B have a distance d2 equal to 8 mm while the tire D has a distance d2 equal to 7 mm. The elimination of the excess thickness of the hooping layer in the shoulder area of the tire D relative to the tire B makes it possible to reduce the distance d2 for the tire D according to the invention to 7 mm as against 8 mm for the tire B while retaining the same tread thickness simply by removing a thickness of hooping layer whose thickness is 0.84 mm. In addition, tire D complies with the following conditions: d1 = 9.45 mm is at least equal to d2 + 0.2 (Rm-Re) = 8.7 mm when tire B does not comply with them: d1 = 9.45 mm and d2 + 0.2 (Rm-Re) = 9.68 mm.
[0064] Le pneumatique D atteint ainsi les mêmes performances que les pneumatiques A et B en vitesse limite et en uniformité mais a une performance en résistance au roulement améliorée de 0.2 Kg/t.
The tire D thus achieves the same performance as the tires A and B in limit speed and uniformity but has an improved rolling resistance performance of 0.2 Kg / t.
Claims
1 . Pneumatique, destiné à être monté sur une jante de montage d’une roue d’un véhicule de tourisme, le pneumatique ayant une largeur axiale hors tout LT monté sur une jante nominale et gonflé à une pression nominale et comportant : 1. Tire, intended to be mounted on a mounting rim of a wheel of a passenger vehicle, the tire having an overall axial width LT mounted on a nominal rim and inflated to a nominal pressure and comprising:
• un axe de rotation (R), un plan équateur (P) passant par le centre de gravité du pneumatique et perpendiculaire à l’axe de rotation (R), An axis of rotation (R), an equator plane (P) passing through the center of gravity of the tire and perpendicular to the axis of rotation (R),
• un sommet (1 ) comprenant une bande roulement (2), destinée à venir en contact avec le sol par l’intermédiaire d’une surface de roulement (21 ) et une armature de sommet (3), comprenant trois couches d’éléments de renforcement (41 , 42, 5), la bande de roulement (2) étant radialement extérieure à l’armature de sommet (3), • a crown (1) comprising a tread (2), intended to come into contact with the ground via a rolling surface (21) and a crown reinforcement (3), comprising three layers of elements reinforcement (41, 42, 5), the tread (2) being radially external to the crown reinforcement (3),
• l’armature de sommet (3) comprenant deux couches de travail (41 , 42) composée d’éléments de renforcement parallèles entre eux formant, avec la direction circonférentielle, un angle compris entre 15° et 50°, The crown reinforcement (3) comprising two working layers (41, 42) composed of reinforcing elements parallel to each other forming, with the circumferential direction, an angle between 15 ° and 50 °,
• l’armature de sommet (3) comprenant également une couche de frettage (5) composée d’éléments de renforcement textile formant, avec la direction circonférentielle, un angle compris entre 0° et 10°, la couche de frettage (5) étant radialement extérieure aux couches de travail, et d’une largeur axiale LF égale à la distance axiale entre les deux points les plus axialement extérieurs de l’armature de frettage, • the crown reinforcement (3) also comprising a hooping layer (5) composed of textile reinforcing elements forming, with the circumferential direction, an angle between 0 ° and 10 °, the hooping layer (5) being radially external to the working layers, and of an axial width LF equal to the axial distance between the two most axially external points of the hooping reinforcement,
• deux bourrelets destinés à venir en contact avec une jante et deux flancs reliant le sommet aux bourrelets, • two beads intended to come into contact with a rim and two sides connecting the top to the beads,
• une armature de carcasse comprenant au moins une couche de carcasse (6), radialement intérieure au sommet et reliant les deux bourrelets, A carcass reinforcement comprising at least one carcass layer (6), radially inner to the top and connecting the two beads,
• la couche de frettage (5) étant constituée par l’enroulement hélicoïdal d’une bandelette d’éléments de renforcement dont la largeur LB mesurée perpendiculairement aux éléments de renforcement est au plus égale à 0.09*LT, The hooping layer (5) being constituted by the helical winding of a strip of reinforcing elements whose width LB measured perpendicular to the reinforcing elements is at most equal to 0.09 * LT,
caractérisé en ce que chaque distance axiale (D1 , DT, D2, D2’) entre les points (51 1 , 512) les plus axialement extérieurs de la couche de frettage (5) et les points (41 1 , 412, 421 , 422) les plus axialement extérieurs de chaque couche de travail situés d’un même côté axial du plan équateur est au moins égale à 0.38*LB et au plus égale à 1 25*LB
• en ce que la couche de frettage (5) est d’épaisseur constante et la largeur axiale LF de la couche de frettage (5) est supérieure aux largeurs axiales (L41 , L42) des couches de travail (41 , 42). characterized in that each axial distance (D1, DT, D2, D2 ') between the most axially outermost points (51 1, 512) of the hooping layer (5) and the points (41 1, 412, 421, 422 ) the most axially outermost of each working layer located on the same axial side of the equator plane is at least equal to 0.38 * LB and at most equal to 1 25 * LB • in that the hooping layer (5) is of constant thickness and the axial width LF of the hooping layer (5) is greater than the axial widths (L41, L42) of the working layers (41, 42).
2. Pneumatique selon la revendication 1 , dans lequel 2. A tire according to claim 1, in which
- le point le plus radialement extérieur (211 ) du pneumatique étant distant de l’axe de rotation (R) d’une distance radiale Rm, mesurée sur le plan équateur, le pneumatique étant monté sur une jante nominale et gonflé à une pression nominale, - the most radially outer point (211) of the tire being distant from the axis of rotation (R) by a radial distance Rm, measured on the equatorial plane, the tire being mounted on a nominal rim and inflated to a nominal pressure ,
- la couche de travail (42) la plus radialement extérieure ayant un point le plus axialement extérieur (421 ), dont le projeté (212) perpendiculairement à la surface de roulement sur la surface de roulement, est à une distance radiale Re de l’axe de rotation R, Re étant mesurée le pneumatique étant monté sur une jante nominale et gonflé à une pression nominale, et ledit projeté (212) étant à une distance d2 du point le plus axialement extérieur (421 ) de la couche de travail (42) la plus radialement extérieure, - the most radially external working layer (42) having an most axially external point (421), the projection (212) of which is perpendicular to the running surface on the running surface, is at a radial distance Re from the axis of rotation R, Re being measured, the tire being mounted on a nominal rim and inflated to a nominal pressure, and said spray (212) being at a distance d2 from the most axially outer point (421) of the working layer (42 ) the most radially outer,
- la distance radiale d1 de la couche de travail (42) la plus radialement extérieure au point le plus radialement extérieur (211 ) du pneumatique mesurée sur le plan équateur (P) est au moins égale à d2 +0,2*(Rm-Re). the radial distance d1 from the most radially outer working layer (42) to the most radially outer point (211) of the tire measured on the equatorial plane (P) is at least equal to d2 +0.2 * (Rm- Re).
3. Pneumatique selon l’une quelconque des revendications précédentes, dans lequel un composé caoutchouteux, dit composé de découplage (7) de la carcasse (6) du sommet (1 ), est radialement extérieur à l’armature de carcasse (6), est radialement intérieur à la couche de travail la plus radialement intérieure (41 ), dont le point le plus axialement intérieur est axialement intérieur au point le plus axialement extérieur (411 ) de la couche de travail la plus radialement intérieure (41 ) et dont le point le plus axialement extérieur (71 ) dudit composé de découplage (7) de la carcasse (6) du sommet (1 ), est axialement extérieur au point le plus axialement extérieur (51 ) de l’armature de frettage (5). 3. A tire according to any one of the preceding claims, in which a rubber compound, known as a decoupling compound (7) of the carcass (6) of the crown (1), is radially external to the carcass reinforcement (6), is radially inner to the most radially inner working layer (41), the most axially inner point of which is axially inner to the most axially outer point (411) of the most radially inner working layer (41) and the the most axially external point (71) of said decoupling compound (7) of the carcass (6) of the crown (1), is axially external to the most axially external point (51) of the hooping reinforcement (5).
4. Pneumatique selon l’une quelconque des revendications précédentes, dans lequel la distance (d3) la plus courte du point le plus axialement extérieur (421 ) de la couche de travail la plus radialement extérieure (42) à la couche de frettage (5) est au moins égale à 0.75 fois la distance (d4) la plus courte du point le plus axialement extérieur (411 ) de la couche de travail la plus radialement intérieure (41 ) à la couche de frettage (5) et au plus égale à 1.25 fois la distance (d4) la plus courte du point le plus axialement extérieur (41 1 ) de la couche de travail la plus radialement intérieure (41 ) à la couche de frettage (5).
4. Tire according to any one of the preceding claims, in which the shortest distance (d3) from the most axially external point (421) of the most radially external working layer (42) to the hooping layer (5 ) is at least equal to 0.75 times the shortest distance (d4) from the most axially outer point (411) of the most radially inner working layer (41) to the hooping layer (5) and at most equal to 1.25 times the shortest distance (d4) from the most axially outer point (41 1) of the most radially inner working layer (41) to the hooping layer (5).
5. Pneumatique selon l’une quelconque des revendications précédentes, comprenant des découpures (25) dans la bande de roulement en surplomb de points les plus axialement extérieurs (421 ) de la couche de travail la plus radialement extérieure (42), pneumatique dans lequel la distance (d5) la plus courte du point (621 ) le plus radialement extérieur de la couche de frettage (5) en surplomb du point le plus axialement extérieur (421 ) de la couche de travail la plus radialement extérieure (42) au fond de la découpure (25) en surplomb, est au moins égale à 1.5 mm et au plus égale à 3 mm, préférentiellement au moins égale à 2 mm et au plus égale à 2.5 mm. 5. A tire according to any one of the preceding claims, comprising cutouts (25) in the tread overhanging the most axially outer points (421) of the most radially outer working layer (42), tire in which the shortest distance (d5) from the most radially outer point (621) of the hooping layer (5) overhanging the most axially outer point (421) of the most radially outer working layer (42) at the bottom of the cutout (25) overhanging, is at least equal to 1.5 mm and at most equal to 3 mm, preferably at least equal to 2 mm and at most equal to 2.5 mm.
6. Pneumatique selon l’une quelconque des revendications précédentes, dans lequel au moins un composé caoutchouteux radialement extérieur aux points les plus radialement intérieurs des découpures (25) a une perte dynamique tanô, mesurée selon la même norme ASTM D 5992 - 96, à une température de 23°C et sous une contrainte de 0,7 MPa à 10 Hz, au plus égale à 0.30, préférentiellement au plus égale à 0.25. 6. Tire according to any one of the preceding claims, in which at least one radially exterior rubber compound at the most radially interior points of the cutouts (25) has a dynamic tanô loss, measured according to the same standard ASTM D 5992-96, a temperature of 23 ° C and under a stress of 0.7 MPa at 10 Hz, at most equal to 0.30, preferably at most equal to 0.25.
7. Pneumatique selon l’une quelconque des revendications précédentes, comprenant des découpures (25) dans la bande de roulement et dans lequel la profondeur maximale des découpures (25) de la bande de roulement est au moins égale à 5 mm et au plus égale à 8 mm, préférentiellement au moins égale à 6 mm et au plus égale à 7 mm. 7. A tire according to any one of the preceding claims, comprising cutouts (25) in the tread and in which the maximum depth of the cutouts (25) in the tread is at least equal to 5 mm and at most equal at 8 mm, preferably at least equal to 6 mm and at most equal to 7 mm.
8. Pneumatique selon l’une quelconque des revendications précédentes, dans lequel les éléments de renforcement d’au moins une couche de travail (41 , 42) sont constitués par des fils métalliques unitaires ou monofilaments ayant une section dont la plus petite dimension est au plus égale à 0.40 mm, préférentiellement au plus égale à 0.30 mm. 8. Tire according to any one of the preceding claims, in which the reinforcing elements of at least one working layer (41, 42) are constituted by unitary metallic wires or monofilaments having a section the smallest dimension of which is at more equal to 0.40 mm, preferably at most equal to 0.30 mm.
9. Pneumatique selon l’une quelconque des revendications précédentes, dans lequel au moins un composé caoutchouteux au contact des éléments de renforcement des couches de travail (41 ,42) a une perte dynamique tanô, mesurée selon la même norme ASTM D 5992 - 96, à une température de 23°C et sous une contrainte de 0,7 MPa à 10 Hz, au plus égale à 0.20, préférentiellement au plus égal à 0.15. 9. Tire according to any one of the preceding claims, in which at least one rubbery compound in contact with the reinforcing elements of the working layers (41, 42) has a dynamic tanô loss, measured according to the same standard ASTM D 5992 - 96 , at a temperature of 23 ° C and under a stress of 0.7 MPa at 10 Hz, at most equal to 0.20, preferably at most equal to 0.15.
10. Pneumatique selon l’une quelconque des revendications précédentes, comprenant des découpures (25) comprenant des rainures transversales axialement extérieures aux points (423) situés à une distance axiale au plus égale à 0.3 x LT du plan équateur (P), ont une largeur au plus égale à 2 mm.
10. A tire according to any one of the preceding claims, comprising cutouts (25) comprising transverse grooves axially external to the points (423) located at an axial distance at most equal to 0.3 x LT from the equator plane (P), have a width at most equal to 2 mm.
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FR1857270 | 2018-08-03 | ||
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JP7498391B2 (en) | 2020-02-18 | 2024-06-12 | 横浜ゴム株式会社 | Pneumatic tires |
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EP2599645A1 (en) * | 2011-12-01 | 2013-06-05 | Sumitomo Rubber Industries Limited | Pneumatic tire |
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DE112014006241T5 (en) * | 2014-01-23 | 2016-10-13 | The Yokohama Rubber Co., Ltd. | tire |
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