Method for controlling the rolling resistance of a running tire and method for reducing the consumption of a running tire

Abstract

The present application discloses a method for controlling the rolling resistance of a driving tire. The method includes: manufacturing a tire (2), mounting the tire (2) on a rim, and mounting the wheel on a vehicle (100). Manufacturing the tire (2) includes: obtaining an external profile of the tire (2) that is asymmetric with respect to the median plane (Pt) of the tire (2) itself, and the external profile is configured to generate a lateral taper force (Co) between the tire (2) rotating during straight running and the ground (S); imparting the asymmetric external profile (1) to the tire (2). The asymmetric external profile (1) is obtained to control the resultant lateral force (F) exchanged between the ground (S) and the tire (2), and to limit the rolling resistance of the tire (2) traveling on a straight trajectory.

Description

Technical Field

[0001] The present invention relates to a method for controlling the rolling resistance of a running tire, a method for reducing the consumption of a running vehicle, a tire for a vehicle wheel, and an apparatus for vulcanizing and molding a tire for a vehicle wheel. Preferably but not exclusively, the present invention relates to road tires intended to equip hybrid or electric vehicles. Background Art

[0002] A tire for a vehicle wheel generally includes a carcass structure associated with a belt structure. A tread is disposed in a radially outer position relative to the belt structure. The tread is the part of the tire that is in direct contact with the road surface, and this part exchanges forces with the road surface, enabling the vehicle to be guided along the trajectory set by the driver.

[0003] The production cycle of a tire provides a process for constructing a green tire, in which various structural components of the tire itself are manufactured and / or assembled, for example, on one or more drums. The constructed green tire is transferred to a molding and vulcanization production line, where the molding and vulcanization processes are actuated, and is adapted to define the structure of the tire according to the desired geometry and tread design.

[0004] Document W02013190419 under the same applicant describes a method for controlling the symmetry of the contact patch area of a tire traveling on a straight trajectory with a non-zero camber angle by arranging any one of the centerlines of the tread in the contact patch area of the tire to be substantially parallel to the ground. This document also describes a tire and wheel for a vehicle, in which in each radial half-section, the corresponding centerline of the tread and the rotation axis of the tire form a predetermined angle whose absolute value is substantially equal to the camber angle. The same document also describes a process for manufacturing a tire for a vehicle wheel, in which a green tire having a cross-section characterized by a symmetric outer profile is deformed during the molding and vulcanization steps until a predetermined non-zero angle is formed between any one of the centerlines of the tread and the rotation axis of the vulcanized tire.

[0005] Document WO2020005285A1 describes a tire that is mounted on a vehicle and capable of generating a lateral ply steer force to reduce the wear of the tire during straight running of the vehicle.

[0006] Document JP2012171433A describes a tire provided with an asymmetric outer profile, which is capable of generating lateral taper forces and lateral ply steer forces that cancel each other out, thereby allowing the rolling resistance to be limited.

[0007] Furthermore, document JPH0692104A describes an asymmetric tire for which the ply steer force and the taper force cancel each other out.

[0008] Document WO2008078431A1 describes a run-flat tire that is mounted with a camber angle and provided with reinforcement members to reduce deformation during driving after puncture.

[0009] Documents JPS57114704A and US4573511A both describe a tire having a structure that reduces the ply steering force generated by the belt layer.

[0010] Document US10457099B2 describes a tire having an asymmetric profile that can control the symmetry of the contact patch area.

[0011] Definitions

[0012] The terms "radial", "axial", and "circumferential" refer to the axis of rotation of the tire or the central axis of the vulcanization and molding cavity. When the tire is in the vulcanization and molding cavity, the axis of rotation coincides with the central axis.

[0013] For the "radial plane", it refers to the plane in which the axis of rotation of the tire lies or the plane in which the central axis of the vulcanization and molding cavity lies.

[0014] For the "outer contour of the tire", it refers to the cross-section of the radial plane in accordance with the radial outer surface of the tire.

[0015] For the "radius of curvature" of a curve, it refers to the radius of the osculating circle at a point on the curve.

[0016] For "curvature", it refers to the reciprocal of the radius of the osculating circle at a point, where the osculating circle is the circle that closely approximates the curve at that point of the curve.

[0017] For the "inner contour of the vulcanization and molding cavity", it refers to the cross-section of the radial plane in accordance with the radial inner surface of the vulcanization and molding cavity.

[0018] For the verb "control", it means pre-verifying and / or setting the possibility of the resultant lateral force acting between the tire and the road by generating additional lateral forces. Summary of the Invention

[0019] The present applicant has observed that during straight-line driving of a vehicle, lateral or transverse forces (i.e., directed perpendicular to the forward direction of the vehicle) are generated between each tire of the vehicle and the road surface, which are caused by various factors, such as forces generated due to the asymmetry of the internal structure of the tire, forces generated due to the camber angle of the tire, and forces generated due to the caster angle of the tire.

[0020] The Applicant has observed that such lateral forces have an influence on the rolling resistance, since, all other influencing factors being equal, the rolling resistance increases as the resultant of these lateral forces increases.

[0021] In this context, the objective set by the Applicant is to control the resistance to the forward movement of the vehicle resulting from the interaction between the tyre and the ground, which is closely related to the rolling resistance.

[0022] The objective set by the Applicant is to reduce consumption or increase the autonomy of the vehicle.

[0023] The objective set by the Applicant is to reduce the overheating of the tyre during travel.

[0024] The Applicant has also set the objective of reducing tyre wear or increasing its run-flat distance (i.e. deflating with a pressure lower than the correct operating pressure), particularly in the case where the tyre is of the run-flat type.

[0025] The tyres manufactured according to document WO2013190419 do not propose a solution to the above problems.

[0026] However, the Applicant has recognised that the above objectives can be achieved by generating an additional lateral force between the tyre and the road, which, by combining with the above-mentioned lateral forces, allows the resultant of these lateral forces to be controlled.

[0027] More precisely, the Applicant has recognised that by generating said additional lateral force and by possibly controlling its magnitude, it is possible to reduce the resultant of the lateral forces.

[0028] The Applicant has finally found that the above objectives can be achieved by means of an asymmetric profile capable of generating such an additional lateral force, which additional lateral force will hereinafter be defined as "lateral taper force".

[0029] According to a first aspect, the invention relates to a method for controlling the rolling resistance of a running tyre.

[0030] The method comprises:

[0031] - manufacturing a tyre, wherein the tyre has an asymmetric internal structure so as to generate a structural lateral force (referred to as Ply-Steer) between the tyre rotating in straight running and the ground;

[0032] - mounting the tyre on a rim;

[0033] - mounting the wheel on a vehicle, wherein the wheel comprises said tyre and said rim, and wherein the tyre is mounted on the wheel with a camber angle so as to generate a lateral camber force between the tyre rotating in straight running and the ground.

[0034] Preferably, manufacturing a tire includes:

[0035] - obtaining an external profile of the tire, the external profile being asymmetric with respect to the median plane of the tire itself and configured to generate a lateral conicity force between the tire rotating during straight running and the ground;

[0036] - imparting the asymmetric external profile to the tire.

[0037] Preferably, one direction of the lateral conicity force does not coincide with one direction of the lateral outward inclination force, and wherein the modulus of the lateral conicity force is less than the modulus of the structural lateral force to control the resultant lateral force including at least the lateral conicity force, the lateral outward inclination force and the structural lateral force, and to limit the rolling resistance of the tire when traveling on a straight trajectory.

[0038] According to a second aspect, the present invention relates to a method for reducing the consumption of a traveling vehicle, the method including performing a method according to one or more of the foregoing aspects and / or according to subsequent aspects and applied to each wheel of the vehicle.

[0039] According to a third aspect, the present invention relates to a tire for a vehicle wheel.

[0040] Preferably, the tire has an asymmetric internal structure; wherein, when a wheel including the tire mounted on a rim is mounted on a vehicle in a manner having a camber angle, the camber angle generates a lateral outward inclination force between the tire rotating during straight running and the ground, and the asymmetric internal structure generates a structural lateral force between the tire rotating during straight running and the ground.

[0041] Preferably, the external profile of the tire is asymmetric with respect to the median plane of the tire itself; wherein the asymmetric external profile is configured to generate a lateral conicity force between the tire rotating during straight running and the ground; wherein one direction of the lateral conicity force does not coincide with one direction of the lateral outward inclination force, and wherein the modulus of the lateral conicity force is less than the modulus of the structural lateral force to control the resultant lateral force including at least the lateral conicity force, the lateral outward inclination force and the structural lateral force, and to limit the rolling resistance of the tire when traveling on a straight trajectory.

[0042] According to a fourth aspect, the present invention relates to an apparatus for vulcanizing and molding a tire for a vehicle wheel.

[0043] Preferably, the apparatus includes a vulcanization mold which, when closed, internally defines a vulcanization and molding cavity, the shape of the vulcanization and molding cavity corresponding to the external shape imparted to the tire once molded and vulcanized.

[0044] Preferably, the apparatus includes means operatively associated with the vulcanization and molding cavity and configured to apply heat and pressure to a tire received in the vulcanization and molding cavity to vulcanize the tire.

[0045] Preferably, a radial cross-section of the vulcanization and molding cavity has an internal profile that is asymmetric with respect to a median plane of the vulcanization and molding cavity to manufacture an asymmetric tire according to at least one of the foregoing aspects or the following aspects.

[0046] The Applicant believes that the present invention allows controlling the rolling resistance of each tire of a vehicle and thus also allows controlling a part of the advancing resistance of the vehicle due to the interaction between the tire and the road.

[0047] The Applicant believes that by an asymmetric external profile suitably obtained for generating a lateral conicity force, it is possible to obtain said lateral conicity force and control its modulus and thus control the resultant lateral force, which is the vector sum of at least one of the above-mentioned lateral forces and said lateral conicity force.

[0048] The Applicant believes that by the asymmetric external profile and the lateral conicity force, it is possible to reduce the resultant lateral force in at least one tire of the vehicle's tires and / or reduce the average value of the resultant lateral force acting on the vehicle's tires.

[0049] The Applicant believes that in this way it is possible to reduce the rolling resistance and thus limit the wear and overheating of the tire or the vehicle's tires, especially when the tire is running with a flat tire, and thus the Applicant also believes that the present invention allows reducing the consumption of the vehicle or increasing the autonomy of the vehicle.

[0050] The present invention may have one or more of the preferred features described below in at least one of the foregoing aspects.

[0051] Preferably, a structural lateral force and a lateral camber force are given.

[0052] Preferably, the external profile is obtained such that the direction of the lateral conicity force is not aligned with the direction of the lateral camber force and the modulus of the lateral conicity force is lower than the modulus of the structural lateral force.

[0053] The Applicant has observed that given the structural lateral force (Ply-Steer) and the lateral camber force, they are not controlled one by one in a sense but result from the internal structure of the tire, the camber angle, the vertical load, etc. Then an asymmetric profile is designed and obtained to generate a lateral conicity force to control the resultant lateral force (the vector sum of the lateral conicity force, the lateral camber force and the structural lateral force) and thus control the rolling resistance.

[0054] Preferably, the asymmetric external profile includes:

[0055] A first portion of the external profile that is interposed between the radial outer surface of the tread band of the tire or between the radial outer surface of the tread band and the axial outer surface of the first sidewall of the tire; and

[0056] A second portion of the external profile that is interposed between the radial outer surface of the tread band of the tire and the axial outer surface of the second sidewall of the tire.

[0057] Preferably, the first portion of the external profile is further from the axis of rotation of the tire and further from the median plane of the tire than the second portion of the external profile.

[0058] Preferably, the first portion of the external profile has a first curvature and the second portion of the external profile has a second curvature, wherein the first curvature is greater than the second curvature.

[0059] Preferably, the lateral conicity force is between 5% and 75% of the structural lateral force, more preferably between 10% and 65%.

[0060] Preferably, the lateral conicity force is between 5% and 225% of the lateral camber force, more preferably between 10% and 195%.

[0061] Preferably, one direction of the lateral conicity force is not the same as one direction of the lateral camber force.

[0062] Preferably, the wheel is mounted with a toe angle so as to generate a lateral toe angle force between the tire rotating during straight running and the ground. Preferably, an asymmetric external profile is obtained as a function of the lateral toe angle force.

[0063] Preferably, one direction of the lateral conicity force is not the same as one direction of the lateral toe angle force to control the resultant lateral force that also includes the lateral toe angle force.

[0064] Preferably, the lateral conicity force is between 5% and 225% of the lateral toe angle force, more preferably between 10% and 195%.

[0065] Preferably, the lateral conicity force is between 10 N and 300 N.

[0066] Preferably, the asymmetric external profile makes the direction of the lateral conicity force not the same as the direction of the lateral camber force, and the modulus of the lateral conicity force is lower than the modulus of the structural lateral force.

[0067] Preferably, by virtually rotating the second radial half-section of the tire onto the first radial half-section of the tire, the first portion of the external profile and the second portion of the external profile define a scythe shape therebetween.

[0068] Preferably, the sickle shape has a maximum thickness measured tangentially to the first part of the outer contour. Preferably, when the tire is at operating pressure, the maximum thickness is between 2% and 33%, more preferably between 4% and 20%, of the radius of curvature of the second part of the outer contour at that point.

[0069] Preferably, when the tire is at operating pressure, the radially outer and axially inner end of the sickle shape is between 60% and 90%, more preferably between 65% and 85%, of the half-width of the tire. Preferably, when the tire is at operating pressure, the radially outer and axially inner end of the sickle shape is between 95% and 99.5%, more preferably between 96% and 98.5%, of the median radius of the tire.

[0070] Preferably, when the tire is at operating pressure, the radially inner and axially outer end of the sickle shape is between 70% and 95%, more preferably between 75% and 90%, of the half-width of the tire.

[0071] Preferably, when the tire is at operating pressure, the radially inner and axially outer end of the sickle shape is between 85% and 97.5%, more preferably between 87.5% and 95%, of the median radius of the tire.

[0072] Preferably, when the tire is at operating pressure, the radially extending height of the sickle shape is between 2% and 14.5%, more preferably between 3% and 12.5%, of the median radius of the tire. Preferably, when the tire is at operating pressure, the axially extending width of the sickle shape is between 5% and 35%, more preferably between 10% and 25%, of the half-width of the tire.

[0073] Preferably, the tire includes a carcass structure provided with a sidewall insert, and the sickle shape has a maximum thickness measured tangentially to the first part of the outer contour. Preferably, when the tire is in a run-flat state, the maximum thickness is between 2% and 33%, more preferably between 4% and 25%, of the radius of curvature of the second part of the outer contour at that point.

[0074] Preferably, the tire includes a carcass structure provided with a sidewall insert, and when the tire is in a run-flat state, the radially outer and axially inner end of the sickle shape is between 60% and 90%, more preferably between 65% and 85%, of the half-width of the tire.

[0075] Preferably, the radially outer and axially inner end of the sickle shape is between 95% and 99.5%, more preferably between 96% and 98.5%, of the median radius of the tire.

[0076] Preferably, the tire comprises a carcass structure provided with a sidewall insert, and when the tire is in the run-flat state, the radially inner and axially outer end of the scythe shape is located between 70% and 95% of the half-width of the tire, more preferably between 75% and 90%.

[0077] Preferably, the radially inner and axially outer end of the scythe shape is located between 85% and 97.5% of the median radius of the tire, more preferably between 87.5% and 95%.

[0078] Preferably, the tire comprises a carcass structure provided with a sidewall insert, and when the tire is in the run-flat state, the radially extending height of the scythe shape is included between 2% and 14.5% of the median radius of the tire, more preferably included between 3% and 12.5%.

[0079] Preferably, the axially extending width of the scythe shape is included between 5% and 35% of the half-width of the tire, more preferably included between 10% and 25%.

[0080] Preferably, the central portion of the asymmetric outer contour that straddles the median plane of the tire is symmetric with respect to the median plane.

[0081] Preferably, when the tire is at the operating pressure, the axially extending width of the symmetric central portion is included between 60% and 90% of the tire width, more preferably included between 65% and 85%.

[0082] Preferably, when the tire is in the run-flat state, the axially extending width of the symmetric central portion is included between 60% and 90% of the tire width, more preferably included between 65% and 85%.

[0083] Preferably, the operating pressure is included between 50 kPa and 400 kPa, more preferably included between 150 kPa and 300 kPa.

[0084] Preferably, the asymmetric inner contour of the radial cross-section of the vulcanization and molding cavity enables the manufacture of an asymmetric tire according to at least one of the foregoing aspects or the following aspects.

[0085] Preferably, the asymmetric inner contour includes a first portion of the inner contour that is interposed between a surface arranged to operate against the tread band of the green tire to be vulcanized and a first surface arranged to operate at least on the first sidewall of the green tire.

[0086] Preferably, the asymmetric inner contour includes a second portion of the inner contour that is interposed between the surface arranged to operate against the tread band and a second surface arranged to operate at least on the second sidewall of the green tire.

[0087] Preferably, the first part of the internal profile is further away from the central axis of the vulcanization and molding cavity and further away from the median plane of the vulcanization and molding cavity than the second part of the internal profile.

[0088] Preferably, the first part of the internal profile has a first curvature and the second part of the internal profile has a second curvature.

[0089] Preferably, the first curvature is greater than the second curvature.

[0090] Preferably, by virtually rotating the second radial half-section of the vulcanization and molding cavity onto the first radial half-section of the vulcanization and molding cavity, the first part of the internal profile and the second part of the internal profile define a sickle shape therebetween.

[0091] Preferably, the sickle shape has a maximum thickness measured perpendicular to the tangent of the first part of the internal profile.

[0092] Preferably, the maximum thickness is between 2% and 33%, more preferably between 4% and 25%, of the radius of curvature of the second part of the internal profile at that point.

[0093] Preferably, the radially outer and axially inner end of the sickle shape is between 60% and 90%, more preferably between 65% and 85%, of half the width of the vulcanization and molding cavity.

[0094] Preferably, the radially outer and axially inner end of the sickle shape is between 95% and 99.5%, more preferably between 96% and 98.5%, of the median radius of the vulcanization and molding cavity.

[0095] Preferably, the radially inner and axially outer end of the sickle shape is between 70% and 95%, more preferably between 75% and 90%, of half the width of the vulcanization and molding cavity.

[0096] Preferably, the radially inner and axially outer end of the sickle shape is between 85% and 97.5%, more preferably between 87.5% and 95%, of the median radius of the vulcanization and molding cavity.

[0097] Preferably, the radial height over which the sickle shape extends is between 2% and 14.5%, more preferably between 3% and 12.5%, of the median radius of the vulcanization and molding cavity.

[0098] Preferably, the axial width over which the sickle shape extends is between 5% and 35%, more preferably between 10% and 25%, of half the width of the vulcanization and molding cavity.

[0099] Preferably, the tire comprises a carcass structure, a belt structure applied around the carcass structure, and a tread applied over the belt structure.

[0100] Preferably, the carcass structure comprises at least one carcass ply having end flaps engaged with corresponding anchoring annular structures.

[0101] Preferably, the belt structure comprises one or more belt plies.

[0102] Preferably, the belt plies are radially superposed relative to each other and relative to the carcass structure and have metal or fabric reinforcing cords with a crosswise orientation and / or extending substantially parallel to the circumferential extension direction of the tire.

[0103] Preferably, corresponding sidewalls made of an elastomeric material are also applied to the side surfaces of the carcass structure, each sidewall extending from one of the side edges of the tread band to the corresponding anchoring annular structure of the bead.

[0104] Preferably, ply-steer is caused by internal asymmetries of the carcass structure and / or the belt structure. The direction of this ply-steer depends on the direction of rotation of the tire.

[0105] Preferably, ply-steer is caused by belt plies arranged at different radial distances from the axis of rotation and having crosswise oriented reinforcing cords.

[0106] Other features and advantages will become more apparent from a detailed description of a method for controlling the rolling resistance of a running tire, a method for reducing the consumption of a running vehicle, a tire for a vehicle wheel, and an apparatus for vulcanizing and molding a tire for a vehicle wheel according to the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0107] Such a description will hereinafter be elaborated with reference to the drawings, which are provided only as non-limiting examples, in which:

[0108] - Figure 1 shows a contour of a tire according to the present invention, which is configured to initiate the method of the present invention;

[0109] - Figure 2 is Figure 1 a virtual superposition of one half of the contour with the other half of the same contour;

[0110] - Figure 3 , Figure 4 and Figure 5 respectively show front views of parts of tires mounted on a vehicle in respective geometric configurations provided with the contours according to Figure 1 and Figure 2 ;

[0111] - Figure 6Shows a top view of a vehicle provided with a tire according to the present invention;

[0112] - Figure 7 Is a radial partial cross-section of the vulcanization and molding cavity of an apparatus for vulcanizing and molding a tire for a vehicle wheel according to the present invention;

[0113] - Figure 8 Is Figure 7 The virtual superposition of one half of the vulcanization and molding cavity 1 with the other half of the same vulcanization and molding cavity;

[0114] - Figure 9 Shows a radial half-section of a tire of a vehicle wheel provided with Figure 1 The profile of. Detailed Description

[0115] Figure 1 The external profile 1 of a tire 2 for a vehicle wheel is shown therein, which is obtained by cutting the radially outer surface of the tire 2 with a radial plane.

[0116] Figure 9 Shows a non-limiting example of the internal structure of a tire 2 for a vehicle wheel. The tire 2 includes a carcass structure 3, the carcass structure including at least one carcass ply 10 having respective opposite end flaps joined to respective anchoring annular structures 8 called bead cores, the anchoring annular structures being capable of being associated with filling inserts 9. The region of the tire 2 including the bead cores 8 and the filling inserts 9 forms a bead structure 7, the bead structure being intended to anchor the tire 2 to a corresponding mounting rim (not shown).

[0117] The carcass structure 10 is associated with a belt structure 4, the belt structure including one or more belt plies 13a, 13b radially superposed relative to each other and relative to the carcass ply 10, the belt plies having metallic or fabric reinforcing cords having a cross orientation and / or extending substantially parallel to the circumferential extension direction of the tire 2.

[0118] In a radially outer position relative to the belt structure 4, a tread band 5 made of an elastomeric composite is applied, as with the other semi-finished products constituting the tire 2. Corresponding sidewalls 6a, 6b made of an elastomeric composite are also applied on the side surfaces of the carcass structure 3, each corresponding sidewall extending from one of the side edges of the tread band 5 until an axially outer position of the corresponding bead structure 7.

[0119] A rubber layer 12, commonly called a "liner", is arranged in a radially inner position relative to the carcass ply 10, the rubber layer providing the necessary impermeability for the inflated air of the tire 2.

[0120] Figure 9The tire 2 is a run-flat tire, i.e., a tire type that allows the tire to travel under acceptable safety conditions even when the tire 2 is partially or completely deflated. For this purpose, the carcass structure 3 includes a sidewall insert 11 (i.e., an annular reinforcing insert made of an elastomeric material), which is applied at the carcass ply 10 and at internal positions in the sidewalls 6a, 6b. When the tire 2 (e.g., as punctured) needs to operate in a partially or completely deflated condition, the sidewall insert 11 is capable of withstanding the loads transmitted between the belt structure 4 and the anchoring annular structure 7.

[0121] Even when not shown in Figure 9 the external profile 1 of the tire 2 is also Figure 1 the external profile.

[0122] The external profile 1 is asymmetric with respect to the median plane "Pt" of the tire 2 to generate a lateral coning force "Co" between the tire 2 rotating in straight running and the ground "S" (shown in Figure 3 , Figure 4 and Figure 5 ).

[0123] As visible in Figure 1 and Figure 2 (by virtually superposing the left half of the external profile 1 of Figure 1 on the right half of the same external profile 1 to obtain a second radial half-section of the tire 2 on a first radial half-section of the tire 2), the external profile 1 includes a central part 14 disposed across the median plane "Pt". This central part 14 corresponds to the radially outer surface of the tread band 5 and is substantially symmetric with respect to the median plane "Pt". More precisely, the central part 14 is strictly symmetric, provided that the section corresponding to the longitudinal slot is replaced by an arc corresponding to the radius of curvature at both sides of the near-vertical walls of the slot.

[0124] The external profile 1 includes a first lateral part 15 and a second lateral part 16 corresponding to the axially outer surfaces of both the first sidewall 6a and the second sidewall 6b of the tire 2.

[0125] The external profile 1 includes: a first part 17 of the external profile interposed between the central part 14 and the first lateral part 15; and a second part 18 of the external profile interposed between the central part 14 and the second lateral part 16.

[0126] As in Figure 2As can be seen more clearly in the figure, the first part 17 of the outer contour is further away from the rotation axis "R" of the tire 2 and further away from the median plane "Pt" of the tire 2 than the second part 18 of the outer contour. Additionally, the first part 17 of the outer contour has a first curvature "1 / r1", the second part of the outer contour has a second curvature "1 / r2", and the first curvature is greater than the second curvature.

[0127] In Figure 2 the virtual superposition of, the first part 17 of the outer contour and the second part 18 of the outer contour delimit a sickle shape therebetween.

[0128] The sickle shape has a radially outer and axially inner end "A" and a radially inner and axially outer end "B" and a maximum thickness "t" measured perpendicular to the tangent "tan" of the first part 17 of the outer contour.

[0129] The radially outer and axially inner end "A" is located at a first axial distance "X1" from the median plane "Pt" and at a first radial distance "Y1" from the rotation axis "R". The radially inner and axially outer end "B" is located at a second axial distance "X2" from the median plane "Pt" and at a second radial distance "Y2" from the rotation axis "R". Additionally, the sickle shape extends a radial height "H" and an axial width "L".

[0130] The dimensions and position of the sickle shape and thus the asymmetry of the tire 2 can vary according to the inflation pressure of the tire 2.

[0131] When the tire 2 is at an operating pressure, for example, between 50 kPa and 400 kPa, the maximum thickness "t" as defined above is included between 2% and 33% of the radius of curvature "r2" of the second part 18 of the outer contour at that point (i.e., at the point where the maximum thickness "t" is measured), the first axial distance "X1" is included between 60% and 90% of half the width "C / 2" of the tire 2, the first radial distance "Y1" is included between 95% and 99.5% of the median radius "RP" of the tire 2, the second axial distance "X2" is included between 70% and 95% of half the width "C / 2" of the tire 2, the second radial distance "Y2" is included between 85% and 97.5% of the median radius "RP" of the tire 2, the radial height "H" is included between 2% and 14.5% of the median radius "RP" of the tire 2, and the axial width "L" is included between 5% and 35% of half the width "C / 2" of the tire 2. Additionally, at the above operating pressure, the axial width "X" of the symmetric central part 14 is included between 60% and 90% of the width of the tire 2.

[0132] When the illustrated tire 2, which is a run - flat type due to the provision of the sidewall insert 11, is in a run - flat state, i.e., when the internal pressure of the tire 2 is substantially equal to the external atmospheric pressure, the maximum thickness "t" as defined above is between 2% and 33% of the radius of curvature "r2" of the second part 18 of the external contour at that point (i.e., the point where the maximum thickness "t" is measured). The first axial distance "X1" is between 60% and 90% of half the width "C / 2" of the tire 2. The first radial distance "Y1" is between 95% and 99.5% of the median radius "RP" of the tire 2. The second axial distance "X2" is between 70% and 95% of half the width "C / 2" of the tire 2. The second radial distance "Y2" is between 85% and 97.5% of the median radius "RP" of the tire 2. The radial height "H" is between 2% and 14.5% of the median radius "RP" of the tire 2. And the axial width "L" is between 5% and 35% of half the width "C / 2" of the tire 2. Additionally, under run - flat conditions, the symmetric central part 14 has an axial width "X" between 60% and 90% of the width of the tire 2.

[0133] To obtain the illustrated asymmetric tire 2, i.e., to impart an asymmetric external contour 1 to the tire 2, such a tire 2 is molded and vulcanized in an asymmetric vulcanization mold 19, which is schematically shown in Figure 7 and Figure 8 and belongs to a vulcanization and molding device (not shown) for tires of vehicle wheels.

[0134] When the vulcanization mold 19 is closed, the vulcanization mold 19 internally delimits a vulcanization and molding cavity 20, which has a shape corresponding to the external shape imparted to the tire 2 after molding and vulcanization. Devices operatively associated with the vulcanization and molding cavity 20 are configured to apply heat and pressure to the tire 2 received in the vulcanization and molding cavity 20 to vulcanize the tire 2.

[0135] As can be seen in Figure 7 and Figure 8 the radial section of the vulcanization and molding cavity 20 has an internal contour 21 that is asymmetric with respect to the median plane "Pc'" of the vulcanization and molding cavity 20 itself, in order to manufacture an asymmetric tire 2. The asymmetric internal contour 21 of the vulcanization and molding cavity 20 is similar to the external contour 1 of the tire 2. The asymmetric internal contour 21 includes: a first part 22 of the internal contour interposed between a surface 23 arranged to operate against the tread band 5 of the green tire 2 to be vulcanized and a first surface 24 arranged to operate at least on the first sidewall 6a of the green tire 2; and a second part 25 of the internal contour interposed between the surface 23 arranged to operate against the tread band and a second surface 26 arranged to operate at least on the second sidewall 6b of the green tire 2.

[0136] As can be seen more clearly in Figure 8 the first part 22 of the inner profile is further away from the central axis "R'" of the vulcanization and molding cavity 20 and further away from the median plane "Pc" of the vulcanization and molding cavity 20 than the second part 25 of the inner profile. Additionally, the first part 22 of the inner profile has a first curvature "1 / r’1", the second part 25 of the inner profile has a second curvature "1 / r’2", and the first curvature is greater than the second curvature.

[0137] In Figure 8 the virtual superposition of, the first part 22 of the inner profile and the second part 25 of the inner profile define a sickle shape therebetween. The sickle shape defined by the inner profile of the vulcanization and molding cavity 20 has a radially outer and axially inner end "A'", a radially inner and axially outer end "B'", and a maximum thickness "t'" measured perpendicular to the tangent "tan'" of the first part 22 of the inner profile.

[0138] The radially outer and axially inner end "A'" is located at a first axial distance "X’1" from the median plane "Pc" and at a first radial distance "Y’1" from the central axis "R’". The radially inner and axially outer end "B'" is located at a second axial distance "X’2" from the median plane "Pc" and at a second radial distance "Y’2" from the central axis "R’". Additionally, the sickle shape extends a radial height "H’" and an axial width "L’".

[0139] The maximum thickness "t’" as defined above is between 2% and 33% of the radius of curvature "r’2" of the second part 25 of the outer profile at that point (i.e., the point where the maximum thickness "t’" is measured), the first axial distance "X’1" is between 60% and 90% of half the width "C’ / 2" of the vulcanization and molding cavity 20, the first radial distance "Y’1" is between 95% and 99.5% of the median radius "RC" of the vulcanization and molding cavity 20, the second axial distance "X’2" is between 70% and 95% of half the width "C’ / 2" of the vulcanization and molding cavity 20, the second radial distance "Y’2" is between 85% and 97.5% of the median radius "RC" of the vulcanization and molding cavity 20, the radial height "H’" is between 2% and 14.5% of the median radius "RC" of the vulcanization and molding cavity 20, and the axial width "L’" is between 5% and 35% of half the width "C’ / 2" of the vulcanization and molding cavity 20. Additionally, the axial width "X’" of the symmetric central part 23 is between 60% and 90% of the width "C’" of the vulcanization and molding cavity 20.

[0140] The above geometry of the internal profile 21 of the vulcanization and molding cavity 20 is obtained based on the geometry of the external profile 1 imparted to the tire 2.

[0141] The present invention also relates to a method for controlling the rolling resistance of a running tire 2 and a method for reducing the consumption of a running vehicle 100.

[0142] According to the method of the present invention, the external profile 1 of the tire 2 is designed and obtained to obtain the above-mentioned lateral taper force "Co". For example, an asymmetric external profile 1 is calculated and manufactured to obtain the lateral taper force "Co", thereby controlling the resultant lateral force "F" exchanged between the ground "S" and the tire 2 traveling on a straight track.

[0143] Once the internal geometry of the tire 2 and the geometry according to which each tire 2 is mounted on the vehicle 100 are known, the following interaction forces between each tire 2 and the ground "S" can be measured or calculated:

[0144] - To lateral camber force;

[0145] - Ca lateral force due to camber;

[0146] - PS structural lateral force.

[0147] The lateral camber force "To" depends on the camber angle "β", and each tire 2 is mounted on the vehicle 100 according to the camber angle. The lateral force due to camber "Ca" depends on the caster angle "α", and each tire 2 is mounted on the vehicle 100 according to the caster angle. The structural lateral force "PS" depends on the asymmetric internal structure of the tire 2, for example, caused by the asymmetry in the carcass structure 3 and / or the belt structure 4, and the structural lateral force "PS" is directed either in the same direction or in the opposite direction as the rotation direction of the tire 2 itself. Generally, the structural lateral force "PS" is caused by belt layers 13a, 13b arranged at different radial distances from the rotation axis "R" and having reinforcing cords with a cross orientation.

[0148] The resultant lateral force "F" includes at least the lateral taper force "Co", the lateral force due to camber "Ca", and the structural lateral force "PS".

[0149] Once the "range" of the above forces for each wheel is known, the external profile 1 of the tire 2 is designed and obtained to obtain a value of the lateral taper force "Co", and the value of the lateral taper force "Co" can modify the resultant lateral force to obtain a different resultant lateral force "F" for each wheel.

[0150] Pre-verifying and / or setting the possibility of the resultant lateral force acting between each tire 2 and the road allows controlling the rolling resistance of each tire 2 and also allows reducing the consumption of the running vehicle 100. For example, Figure 3Shows a wheel (with a rim and a tire 2) mounted on a vehicle 100 at a beam angle and camber angle equal to 0°, such that the only two lateral forces present are the structural lateral force "PS" and the lateral conicity force "Co" in opposite directions, so that the lateral conicity force "Co" partially balances the structural lateral force "PS". In Figure 3 the tire 2, the second part 18 of the outer contour is on the left side, while the first part 17 of the outer contour is on the right side. The structural lateral force "PS" points towards the vehicle 100 (located Figure 3 on the left side in

[0151] For example, Figure 4 shows a wheel (with a rim and a tire 2) mounted on a vehicle 100, which is a right front wheel when viewed from the front, with a non-zero beam angle and camber angle and precisely a positive beam angle and a negative camber angle, so that all lateral forces are present. In Figure 4 the tire 2, the second part 18 of the outer contour is on the right side while the first part 17 of the outer contour is on the left side. The lateral beam angle force "To" and the lateral camber force "Ca" point towards the vehicle 100 (on the Figure 4 right side in

[0152] For example, Figure 5 shows a wheel (with a rim and a tire 2) mounted on a vehicle 100, which is a left front wheel when viewed from the front, with a non-zero beam angle and camber angle and precisely a positive beam angle and a negative camber angle, so that all lateral forces are present. In Figure 5 the tire 2, the second part 18 of the outer contour is on the left side while the first part 17 of the outer contour is on the right side. The structural lateral force "PS", the lateral beam angle force "To" and the lateral camber force "Ca" point towards the vehicle 100 ( Figure 5to the left in the figure), while the lateral taper force "Co" points in the opposite direction, i.e., on the opposite side with respect to the vehicle 100. For example, if the lateral taper force "Co" is approximately 40% of the structural lateral force "PS" (e.g., PS = 350 N and Co = 140 N), the lateral camber force "To" is approximately 50% of the structural lateral force "PS" (To = 175 N), and the lateral slip angle force "Ca" is approximately 30% of the structural lateral force "PS" (e.g., Ca = 105 N), then the resultant lateral force "F" points towards the vehicle 100 and has a value of approximately 490 N.

[0153] As an example, Figure 6 shows the vehicle 100, where the lateral forces acting on each wheel are indicated. The lateral camber force "To" and the lateral slip angle force "Ca" point inward towards the vehicle 100. The lateral taper force "Co" points outward. The structural lateral forces "PS" all point to the same side because the tires 2 on one side rotate in the opposite direction relative to the tires 2 on the other side.

[0154] Under the same other conditions (e.g., the vertical load acting on the wheels, the inflation pressure of the tires, etc.), the rolling resistance "Rt" of the tire 2 during straight running will increase as the resultant lateral force "F" exchanged between the ground "S" and the tire 2 increases, and the rolling resistance "Rv" of the vehicle 100 is the sum of the rolling resistances "Rt" of each tire 2.

[0155] The generation of the lateral taper force "Co" allows for a reduction in the rolling resistance "Rv" of the vehicle 100 (or the average rolling resistance of each tire 2, which is intended to be the rolling resistance "Rv" of the vehicle 100 divided by the number of wheels), and thus reduces the consumption of the moving vehicle 100 because on some tires ( Figure 6 the tires of the left wheels in the figure), the lateral taper force "Co" reduces the resultant lateral force "F".

[0156] The following table contains values from simulation tests involving a vehicle equipped with reference tire A and another vehicle equipped with tire B according to the present invention.

[0157] Tire A

[0158] Symmetrical external profile, which does not generate any lateral taper force (Co = 0).

[0159] Asymmetrical internal structure, which generates a structural lateral force (PS). This tire is mounted on the vehicle in such a way as to have a camber angle that generates a lateral slip angle force (Ca) and a caster angle that generates a lateral camber force (To), as Figure 6 shown.

[0160] Tire B

[0161] Asymmetric outer contour (according to the invention), which generates a lateral conicity force (Co).

[0162] This tire B has the same internal structure as tire A and is mounted on the same vehicle with the same camber angle and toe angle as tire A (the vertical load acting on the wheel is the same).

[0163] The inflation pressure of both tire A and tire B is 2.2 bar.

[0164] The value RR% in the last column on the right is the normalized value of RR under the condition of equal vertical load and pressure but zero toe angle and camber angle. Therefore, by setting RRref (the second - last column on the right) of both tire A and tire B with zero toe angle and camber angle to 100, the expected RR% (the last column on the right) of the four wheels during straight - line driving under toe - angle and camber - angle conditions can be obtained.

[0165]

[0166]

[0167]

[0168] It can be seen that on the wheels FL, RL, RR, the sum of the lateral forces of tire B with a conical contour according to the invention and thus the change in RR% (relative to the condition of zero toe angle and camber angle) is lower than that of tire A.

[0169] Only at the right front wheel FR, the absolute value of the sum of the lateral forces is higher in case B, so the increase in RR% is greater. On the other three wheels, the absolute value of the sum of the lateral forces of tire B is always lower than that of tire A, so the change in RR% is favorable, that is, lower.

[0170] It can be seen that the change in the average RR% of tire B with a conical contour (100.41) is lower than that of tire A (102.77), and thus tire B according to the invention can achieve the purpose stated in this specification.

Claims

1. A method for controlling the rolling resistance of a traveling tire, the method comprising: - manufacturing a tire (2), wherein the tire (2) has an asymmetric internal structure so as to generate a structural lateral force (PS) between the tire (2) rotating during straight running and the ground (S); - mounting the tire (2) on a rim; - mounting a wheel on a vehicle (100), wherein the wheel includes the tire (2) and the rim, and wherein the wheel is mounted at a camber angle (α) so as to generate a lateral camber force (Ca) between the tire (2) rotating during straight running and the ground (S); wherein manufacturing the tire (2) includes: - obtaining an external profile (1) of the tire (2) that is asymmetric with respect to the median plane (Pt) of the tire (2) itself, and the external profile is configured to generate a lateral taper force (Co) between the tire (2) rotating during straight running and the ground (S); - imparting the asymmetric external profile (1) to the tire (2); wherein one direction of the lateral taper force (Co) is not consistent with one direction of the lateral camber force (Ca), and wherein the modulus of the lateral taper force (Co) is less than the modulus of the structural lateral force (PS) to control a resultant lateral force (F) that at least includes the lateral taper force (Co), the lateral camber force (Ca), and the structural lateral force (PS), and to limit the rolling resistance of the tire traveling on a straight track.

2. The method according to claim 1, wherein The asymmetric external profile (1) includes: a first portion (17) of the external profile interposed between the radially outer surface of the tread band (5) of the tire (2) and the axially outer surface of the first sidewall (6a); and a second portion (18) of the external profile interposed between the radially outer surface of the tread band (5) of the tire (2) and the axially outer surface of the second sidewall (6b); wherein the first portion (17) of the external profile is farther from the rotation axis (R) of the tire (2) and farther from the median plane (Pt) of the tire (2) than the second portion (18) of the external profile; wherein the first portion (17) of the external profile has a first curvature (1 / r1) and the second portion (18) of the external profile has a second curvature (1 / r2), and wherein the first curvature (1 / r1) is greater than the second curvature (1 / r2).

3. The method according to claim 1 or 2, wherein The lateral taper force (Co) is between 5% and 75% of the structural lateral force (PS).

4. The method according to claim 1 or 2, wherein The lateral taper force (Co) is between 5% and 225% of the lateral camber force (Ca).

5. The method according to claim 1 or 2, wherein Mounting the wheel at a ply angle (β) so as to generate a lateral ply angle force (To) between the tire (2) rotating during straight running and the ground.

6. The method according to claim 5, wherein One direction of the lateral taper force (Co) is not consistent with the direction of the lateral ply angle force (To) to control the resultant lateral force (F) that also includes the lateral ply angle force (To).

7. The method according to claim 6, wherein The lateral taper force (Co) is between 5% and 225% of the lateral bundle angle force (To).

8. A method for reducing the consumption of a moving vehicle, the method comprising performing the method according to any one of claims 1 to 7 on each wheel of the wheels of the vehicle (100).

9. A tire for a vehicle wheel, wherein, The tire (2) has an asymmetric internal structure; Wherein, when a wheel including the tire (2) mounted on a rim is mounted on the vehicle (100) with a camber angle (α), the camber angle (α) generates a lateral camber force (Ca) between the tire (2) rotating in a straight line and the ground (S), and the asymmetric internal structure generates a structural lateral force (PS) between the tire (2) rotating in a straight line and the ground (S); The tire (2) has an external profile (1) asymmetric with respect to the median plane (Pt) of the tire (2) itself; Wherein, the asymmetric external profile (1) is configured to generate a lateral taper force (Co) between the tire (2) rotating in a straight line and the ground (S); Wherein, one direction of the lateral taper force (Co) is not consistent with the direction of the lateral camber force (Ca), and wherein the modulus of the lateral taper force (Co) is less than the modulus of the structural lateral force (PS) to control the resultant lateral force (F) including at least the lateral taper force (Co), the lateral camber force (Ca) and the structural lateral force (PS), and limit the rolling resistance of the tire (2) traveling on a straight track.

10. The tire according to claim 9, wherein, The asymmetric external profile (1) includes: A first portion (17) of the external profile interposed between the radially outer surface of the tread band (5) of the tire (2) and the axially outer surface of the first sidewall (6a); and A second portion (18) of the external profile interposed between the radially outer surface of the tread band (5) of the tire (2) and the axially outer surface of the second sidewall (6b); Wherein, the first portion (17) of the external profile is farther from the rotation axis (R) of the tire (2) and farther from the median plane (Pt) of the tire (2) than the second portion (18) of the external profile; Wherein, the first portion (17) of the external profile has a first curvature (1 / r1) and the second portion (18) of the external profile has a second curvature (1 / r2), wherein the first curvature (1 / r1) is greater than the second curvature (1 / r2).

11. The tire according to claim 10, wherein, By virtually rotating the second radial half-section of the tire (2) onto the first radial half-section of the tire (2), the first portion (17) of the external profile and the second portion (18) of the external profile define a sickle shape between the first portion and the second portion.

12. The tire according to claim 11, wherein, The sickle shape has a maximum thickness (t) measured perpendicular to the tangent of the first part (17) of the outer contour, and when the tire (2) is at the operating pressure, the maximum thickness (t) is between 2% and 33% of the radius of curvature (r2) of the second part (18) of the outer contour at the measurement point.

13. The tire according to claim 12, wherein, When the tire (2) is at the operating pressure, the radially outer and axially inner end (A) of the sickle shape is between 60% and 90% of half the width (C / 2) of the tire (2) and between 95% and 99.5% of the median radius (RP) of the tire (2).

14. The tire according to claim 12 or 13, wherein, When the tire (2) is at the operating pressure, the radially inner and axially outer end (B) of the sickle shape is between 70% and 95% of half the width (C / 2) of the tire (2) and between 85% and 97.5% of the median radius (RP) of the tire (2).

15. The tire according to claim 12 or 13, wherein, When the tire (2) is at the operating pressure, the radially extending height (H) of the sickle shape is between 2% and 14.5% of the median radius (RP) of the tire (2), and the axially extending width (L) of the sickle shape is between 5% and 35% of half the width (C / 2) of the tire (2).

16. The tire according to claim 11, the tire comprising a carcass structure provided with a sidewall insert (11), wherein the scythe shape has a maximum thickness (t) measured perpendicular to a tangent of a first portion (17) of the outer contour, wherein, When the tire (2) is in the run - flat state, the maximum thickness (t) is between 2% and 33% of the radius of curvature (r2) of the second part (18) of the outer contour at the measurement point.

17. The tire according to claim 11 or 16, the tire comprising a carcass structure (3) provided with a sidewall insert (11), wherein, When the tire (2) is in the run - flat state, the radially outer and axially inner end (A) of the sickle shape is between 60% and 90% of half the width (C / 2) of the tire (2) and between 95% and 99.5% of the median radius (RP) of the tire (2).

18. The tire according to claim 11 or 16, the tire comprising a carcass structure (3) provided with a sidewall insert (11), wherein, When the tire (2) is in the run - flat state, the radially inner and axially outer end (B) of the sickle shape is between 70% and 95% of half the width (C / 2) of the tire (2) and between 85% and 97.5% of the median radius (RP) of the tire (2).

19. The tire according to claim 11 or 16, said tire comprising a carcass structure (3) provided with a sidewall insert (11), wherein, When the tire (2) is in the run - flat state, the radially extending height (H) of the sickle shape is between 2% and 14.5% of the median radius (RP) of the tire (2), and the axially extending width (L) of the sickle shape is between 5% and 35% of half the width (C / 2) of the tire (2).

20. The tire according to any one of claims 10 to 13, wherein, The central part (14) of the asymmetric outer contour arranged across the median plane (Pt) of the tire (2) is symmetric with respect to the median plane (Pt).

21. An apparatus for vulcanizing and molding a tire for a vehicle wheel, the apparatus comprising: A vulcanization mold (19) which, when closed, internally defines a vulcanization and molding cavity (20) having a shape corresponding to the outer shape imparted to the tire (2) after molding and vulcanization. Apparatus operatively associated with the vulcanization and molding cavity (20) and configured to apply heat and pressure to the tire (2) received in the vulcanization and molding cavity (20) to vulcanize the tire (2); wherein the radial cross-section of the vulcanization and molding cavity (20) has an internal profile (21) that is asymmetric with respect to the median plane (Pc) of the vulcanization and molding cavity (20) to manufacture a tire (2) according to any one of claims 9 to 20.

22. The apparatus according to claim 21, wherein, The asymmetric internal profile (21) includes: a first portion (22) of the internal profile interposed between a surface operative against the tread band (5) of the green tire (2) to be vulcanized and a first surface operative at least on the first sidewall (6a) of the green tire (2); and a second portion (25) of the internal profile interposed between the surface operative against the tread band (5) and a second surface operative at least on the second sidewall (6b) of the green tire (2); wherein the first portion (22) of the internal profile is further from the central axis (R’) of the vulcanization and molding cavity (20) and further from the median plane (Pc) of the vulcanization and molding cavity (20) than the second portion (25) of the internal profile; wherein the first portion (22) of the internal profile has a first curvature (1 / r’1) and the second portion (25) of the internal profile has a second curvature (1 / r’2), wherein the first curvature (1 / r’1) is greater than the second curvature (1 / r’2).

23. The device according to claim 22, wherein, By virtually rotating the second radial half-section of the vulcanization and molding cavity (20) onto the first radial half-section of the vulcanization and molding cavity (20), the first portion (22) of the internal profile and the second portion (25) of the internal profile define a sickle shape between the first and second portions.

24. The apparatus according to claim 23, wherein, The sickle shape has a maximum thickness (t’) measured perpendicular to the tangent of the first portion (22) of the internal profile, wherein the maximum thickness (t’) is between 2% and 33% of the radius of curvature (r’2) of the second portion (25) of the internal profile at the measurement point.

25. The device according to claim 23 or 24, wherein, The radially outer and axially inner end (A’) of the sickle shape is between 60% and 90% of the half-width (C / 2’) of the vulcanization and molding cavity (20) and between 95% and 99.5% of the median radius (RC) of the vulcanization and molding cavity (20).

26. The device according to claim 23 or 24, wherein, The radially inner and axially outer end (B’) of the sickle shape is between 70% and 95% of the half-width (C / 2’) of the vulcanization and molding cavity (20) and between 85% and 97.5% of the median radius (RC) of the vulcanization and molding cavity (20).

27. The apparatus according to claim 23 or 24, wherein The radially extending height (H’) of the sickle shape is included between 2% and 14.5% of the median radius (RC) of the vulcanization and molding cavity (20), and the axially extending width (L’) of the sickle shape is included between 5% and 35% of half of the width (C’ / 2) of the vulcanization and molding cavity (20).

Images