WO2017103836A1

WO2017103836A1 - Pneumatic tire having a radial ply or bias ply carcass with a grooved sidewall

Info

Publication number: WO2017103836A1
Application number: PCT/IB2016/057650
Authority: WO
Inventors: Hervé FERIGO; José Merino Lopez
Original assignee: Compagnie Générale Des Établissements Michelin; Michelin Recherche Et Technique S.A.
Priority date: 2015-12-19
Filing date: 2016-12-15
Publication date: 2017-06-22
Also published as: FR3045488A1; FR3045488B1

Abstract

Pneumatic tire for a rolling assembly comprising a wheel rim and a pneumatic tire, said pneumatic tire comprising at least one carcass reinforcement (2) which is provided with cords and on top of which a crown reinforcement (3) is located in the radially outward direction, the crown reinforcement (3) being composed of at least one ply of reinforcing elements; the tread (4) is connected to two beads (5) by means of two sidewalls (6), the beads (5) being able to come into contact with a wheel rim (7) that has rim gutter tips (7b); each bead (5) includes at least one circumferential reinforcing element; on their outer surface, the sidewalls (6) have a succession of alternating protrusions (8) and recesses (9), each protrusion (8) being located on the surface of the sidewall (6); the protrusions (8) are arranged at regular or irregular intervals in a continuous manner between a point A and a point E.

Description

PNEUMATIC TIRE WITH RADIAL OR FLOORED CARCASE GROOVE

TECHNICAL FIELD OF THE INVENTION

The invention relates to radial carcass or cross-carcass tires.

STATE OF THE PRIOR ART

[0002] Radial-carcass tires have gradually imposed themselves on various markets, and in particular the tire market for passenger vehicles. This success is due in particular to the endurance, comfort and low rolling resistance qualities of radial technology.

The main parts of a tire are the tread, the sidewalls and the beads. The beads are intended to come into contact with the rim. In a tire of radial technology, each of the main parts constituting the tire, namely the tread, the sidewalls and the beads, has functions well separated from each other, and therefore has a specific constitution well known.

The radial tire is substantially reinforced by a carcass reinforcement comprising at least one carcass ply having an angle substantially equal to 90 ° with respect to the circumferential direction of the tire. This carcass reinforcement is surmounted radially on the outside, and under the tread, reinforcing plies forming a belt.

The cross-carcass tire is distinguished from a tire of radial technology by the presence of at least two crossed carcass plies whose angle is different from 90 ° with respect to the circumferential direction of the tire. Tablecloths are said to be "crossed" because the angles are of opposite signs from one tablecloth to another.

It is recalled that, according to the invention, the circumferential direction of the tire is the direction in a plane perpendicular to the axis of rotation of the tire and tangent to the belt reinforcement of the tire.

Following the appearance of radial tire carcass, some cross-carcass tires have also been provided with a belt reinforcement under the tread. In both types of tire, the tread, in contact directly with the ground, has a particular function to ensure contact with the road and must adapt to the shape of the ground. The flanks, meanwhile, absorb the irregularities of the ground while transmitting the mechanical forces necessary to carry the load of the vehicle and ensure its movement.

The belt reinforcement is an armature which must, on the one hand, be sufficiently rigid vis-à-vis the edge deformations so that the tire develops the drift thrusts necessary for its guidance, and transmit the engine torque or braking, and secondly, be very flexible in bending, that is to say allow variations in curvature of its plane to ensure a contact surface of the tire on the ground sufficient.

Therefore, the belt reinforcement generally has a composite structure, allowing it to have the required rigidity for a relatively low weight. The belt reinforcement generally consists of at least two plies with different angles, including reinforcements, cable-shaped, coated with rubber. The reinforcing elements are crossed from one sheet to the other with respect to the circumferential direction and are symmetrical or not with respect to this direction.

It is already known from JP2008068716A of the tire comprising flanks with external reinforcements, intended to reduce the internal temperature in the tire where deterioration can occur with use.

But the provision of these reinforcements on the sides does not properly reinforce the sidewalls of a tire during side impacts, such as shocks on the sidewalks or in potholes.

Indeed, such shocks performed at different speeds and / or with different angles of attack on conventional tire architectures can cause damage, which can sometimes go as far as the scrapping of the tire.

In addition, the current trend of using aluminum rims, rather than steel to contribute in particular to the overall aesthetic appearance of the vehicle, has the consequence of causing, during side impacts on the tire, the rupture constituents of the carcass from significantly lower speeds. Furthermore, the current desire to use tires with smaller and smaller sidewall heights, has the further consequence that a shock on such sidewall causes degradation with a higher intensity than with larger flanks, and therefore more deteriorating for the tire.

It is also known from JP2003 237317 a tire comprising discontinuous portions of elastomeric gum having different stiffnesses, and disposed on the sidewalls so as to reduce the noise inherent in its operation.

The patent FR888 453 also discloses pneumatic envelopes whose two sides include elastomeric rubber projections intended to verify that the pressure of the tire is consistent with the load due to the geometric shape they have.

Finally, the document US2 354 715 discloses the presence of elastomeric gum growths comprising metal elements, and disposed on the ends of the tread of a tire intended to prevent slippage during travel.

Moreover, during an impact with a sidewalk or with a pothole, the tire can be damaged, for example by jamming between the rim and the obstacle. Following such impact, reinforcement elements of the tire sidewall may be damaged. The tire may locally deform and / or lose its inflation pressure. Several known solutions make it possible to reduce these risks. For example, an increase in the breaking strength of the carcass reinforcement cables according to one of the following approaches:

- Increasing the breaking stress of the material (example: aramid or aramid / nylon or aramid / PET hybrid cable);

- increase of the section of reinforcements (example: cables of larger diameter);

- Increasing the number of reinforcing layers (typically bi-layer solutions).

The reduction of the sidewall thickness associated with the use of cable with increased rupture strength or multi-layer cable (Bi-NC) causes sensitivity to sidewalk grating or any other sidewall damage. It is therefore necessary to increase the thickness of the sidewall. Also, there remains the need to be able to further improve the robustness of the sides of the tires vis-à-vis lateral shocks, without changing their current dimensions.

SUMMARY OF THE INVENTION

To do this, the invention provides a tire for a wheel assembly comprising a rim having rim hooks and a tire, said tire having at least one carcass reinforcement provided with cables and radially surmounted externally. a crown reinforcement, itself radially inside a tread having two axially outermost ends, said crown reinforcement consisting of at least one layer of reinforcement elements, said tread being connected to two beads by means of two flanks, said beads being intended to come into contact with a rim, each bead having at least one circumferential reinforcing element, said flanks comprising, on their outer surface, a series of alternating protuberances with hollows;

each protrusion extending on the surface of the sidewall, said protuberances being disposed regularly or irregularly and continuously between a point A and a point E,

the position of the point A lying between R ₂ + 10 mm and the intersection of the radially outer surface of the tread and the sidewall, and of a radial axis ZZ 'distant from the equatorial plane AA' of a width L _A between ½ (L-60mm) and ½ (L-10mm), where L is the nominal flange size, and said point E is disposed within a radius in R ₂ >RE> R _s + 0.2 (R ₂ - R _s ), R ₂ being the radius corresponding to the position of the top of the hook of a corresponding rim and Rs being the radius of the seat of the corresponding rim.

This architecture minimizes the amount of elastomeric material used at the sidewall without degrading the resistance of the tire to shocks. The planned arrangement also makes it possible to reduce the rolling resistance of the tire.

Alternatively, R ₂ > R _E > R _s + 0.3 (R ₂ -R _s ). R 1 can be in the range between (0.8R ₂ + 0.2R _A ) and (0.2R ₂ + 0.8RA).

The tire according to the invention has the advantage of being quick and easy to achieve, and to withstand particularly violent side shocks without creating significant damage that could possibly cause significant risks to the vehicle passengers.

The tire according to the invention also has the advantage of having overall performance, such as rolling resistance, wear, endurance similar to that of tires without protuberances on the sidewall.

Advantageously, said tread comprises, at least one axially outermost end, a circumferential groove.

According to a first variant, at least one protuberance partially or totally interrupts said circumferential groove.

When the protrusion partially interrupts the groove, this interruption is performed between 2 and 97% of the total axial distance of said groove, preferably between 20 and 80%, and more preferably between 30 and 50%.

According to another variant, each protuberance is adjacent to the circumferential groove.

According to another variant, at least two adjacent protuberances or not penetrate into said circumferential groove.

Advantageously, the outer surface of the sidewall is between 0.2 and 2mm.

[0033] Preferably, the diameter of said cables of the carcass reinforcement is greater than 1 mm.

[0034] Advantageously, the cables of said carcass reinforcement are hybrid cables.

Preferably, the hybrid cables are aramid / nylon or aramid / PET.

Preferably, at least one protuberance has a height and a length, said height being optimal in the center of said length of said protuberance. Preferably, the height of a protuberance is minimal at the level of the nominal flange size. Preferably, at least two protuberances have a length different from each other.

Preferably, each protuberance has a mean height H of between 3 and 10 mm and more preferably between 5 and 8 mm.

Preferably, each protuberance has an average width of between 4 and 12mm.

The protuberances may have an average height greater than 80% of the maximum height over at least 80% of the distance between the points A and E. The average height is defined as being the average of the height between the ends of the body. a protuberance.

The protuberances preferably have a rake angle of less than or equal to 20 °, and preferably between 5 and 8 °.

Two adjacent protuberances may be spaced from each other by an average distance less than or equal to 2 times the average width of a protrusion, and may be substantially parallel to each other.

The protuberances preferably cover at least 40% of the total circumferential surface of the flank between points A and E.

Each protuberance, of defined geometric shape or any one, may comprise a neutral fiber, passing through a radially innermost end and a radially outermost end, and having an angle β, with respect to the radial direction ZZ ' between -60 ° and + 60 °.

The outer sidewall of the tire (that is to say outside when mounted on the vehicle) and the inner side of the tire (that is to say inside when mounted on the tire). vehicle) may comprise each of the protuberances in any combination of possible inclinations.

Similarly, the four tires of a vehicle may have variable inclinations depending on each axle and / or on the same axle.

Preferably, the hollow between two adjacent protuberances extends axially in the extension of the hollow of a circumferential groove of the tread, passing by the point A, said groove being disposed on at least one axial end of the tread.

Preferably, the hollow between two adjacent protuberances has an angle, with the circumferential direction between -15 ° and + 15 ° in an area of the sidewall close to the point A, that is to say between 3 and 8 mm.

The tire according to the invention may have a ratio [sum of the total widths of each protuberance in the circumferential direction on a radius R1] / 2πR greater than or equal to 30%, and more preferably equal to 60%, the widths of each protrusion being defined at 50% of the total height of said protrusion and for any radius R of the tire in the interval R _E <R <RA with R _A the radius of the point A and R _E the radius of the point E.

The invention also provides a mounted assembly comprising a rim and the tire as described above.

The protuberance may be present over the entire circumferential length of the tire sidewall.

The protuberances on the flanks are advantageously made of a material identical to that of the flanks.

BRIEF DESCRIPTION OF THE FIGURES

The invention will now be described with the aid of the examples and drawings which follow and which are given purely by way of illustration, and in which:

FIG. 1 schematically represents a rim hook on which a bead of a tire according to the invention is placed,

FIGS. 2, 3 and 4 show, schematically, a section of a tire of the invention in a radial plane;

FIGS. 5 and 6 show, schematically and in three dimensions, a portion of a sidewall and the corresponding tread of a tire according to the invention, FIG. 7 schematically represents an enlarged portion of a sidewall comprising protuberances of a tire according to the invention,

FIG. 8 represents a sectional view, of two adjacent protuberances of a tire according to the invention, along the axis AA of FIG. 7,

FIGS. 9A and 9B show, in a first variant, a portion of a radially outer portion of a sidewall and the corresponding three-dimensional tread of a tire according to the invention,

FIG. 10A represents, according to a second variant, a portion of a radially outer portion of a sidewall and of the corresponding three-dimensional tread of which certain protuberance completely interrupts a circumferential groove of a tire according to the invention,

- Figure 10B shows, in another variant, a portion of a radially outer portion of a sidewall and the corresponding tread in three dimensions, some protuberance partially interrupts a circumferential groove of a tire according to the invention,

- Figure 1 1A is a partial radial sectional view of a portion of a sidewall and a portion of the corresponding tread according to another variant,

FIG. 11B is a partial view in radial section of a portion of a sidewall and a part of the corresponding tread according to another variant of a tire according to the invention,

Figure 12 illustrates the protuberances in relation to the adjacent reinforcing cables.

In the different figures, identical or similar technical elements bear the same reference. Their description is not repeated so as not to weigh down the text.

DETAILED DESCRIPTION OF THE INVENTION DEFINITIONS

[0054] Hereinafter denoted by: - "longitudinal or circumferential direction": rolling direction of the tire,

- "radial direction": direction intersecting the axis of rotation of the tire and perpendicular to it,

- "axial direction": direction parallel to the axis of rotation of the tire,

- "radially inner to" means closer to the axis of rotation,

- "radially outside" means more distant from the axis of rotation,

- "equatorial plane or median plane": plane perpendicular to the axis of rotation of the tire and which divides the tire into two substantially equal halves,

- "transverse direction of the tire": direction parallel to the axis of rotation,

- "radial or meridian plane" means a plane which contains the axis of rotation of the tire.

By the terms "partially interrupts" is meant that the radially upper end of a protuberance partially intersects the circumferential groove.

By the terms "completely interrupts" is meant that the radially upper end of a protuberance reaches the axially outer end of the tread which is closest thereto.

The groove is an area of a given width located around the point A, and having a longitudinal void ratio greater than 70%.

By the term "regular", it is defined that the protuberances arranged between the points A and E are disposed vertically to one another in a radial direction, with possible symmetry, and uniformly.

By the term "irregular", it is defined that the protuberances arranged between the points A and E are arranged in an offset manner in two parallel radial directions without symmetry and non-uniform manner.

The radius R _A is a function of the length L _A , itself a function of the length L.

The nominal flange size L is defined by the coil size of a tire mounted on the rim and inflated; the flange size being, according to the invention, the distance between the outside of the flanks of an inflated tire, by incorporating the surface relief of the flanks. Ri corresponds to the radius of the point on the outer surface of the flank furthest from the median plane.

[0062] REQ is the radius at the widest point of the tire (width = L): R _A > REQ.

As shown in FIG. 4, the general-purpose passenger vehicle tire 1 comprises a radially inner carcass reinforcement 2 to a general reference belt reinforcement 3, said belt reinforcement 3 being radially interior to a strip of reinforcement. bearing 4 itself connected to two beads 5 via two sidewalls 6. The beads 5 are intended to come into contact with a rim 7 (partially shown). Each bead comprises at least one circumferential reinforcing element 7a. The flanks comprise, on their surface, a series of regularly alternating protuberances 8 with recesses 9 (shown in FIGS. 5 and 6).

In Figure 4 we can see a protrusion 8, in section, having a continuous neutral fiber. It is recalled here that a neutral fiber is called a neutral axis which passes substantially in the center of the volume of each protuberance, and which undergoes neither shortening nor elongation when it is subjected to compression and / or depression.

As shown in Figure 4, the protuberances 8 are disposed on the surface of the sidewall, a continuous neutral fiber length which extends from a point A to a point E.

The point E is disposed at a radius less than R _s + 0.25 (R ₂ - R _s ). Ri is the radius of the nominal flange size L, and R _A is the radius of the point A.

FIG. 1 makes it possible to clearly visualize the position of the point E. As shown in FIG. 1, the point E, corresponding to the base of the protuberance 8, is located against the inner zone of the rim hook, radially inwardly of the rim. rollover 7b of the rim hook.

According to an exemplary embodiment, the point E is disposed at a radius of 210mm for a reference tire 205/55 R 16 mounted on a rim 6.5 J 16 for which R _A is equal to 298mm, R ₂ is equal to 220mm and R < _\ is equal to 261 mm.

The point A is between R ₂ + 10 mm, (as shown in the example of Figure 3), and the intersection of the radially outer surface of the tread and the sidewall, and a radial axis ZZ 'distant from the equatorial plane AA' of length L _A between ½ (L- 60mm) and ½ (L-10mm) (as shown in the example of Figure 2), where L is the nominal flange size.

For a reference tire 205/55 R 16, R _A is equal to 298mm.

The protuberances are not inserted rubber elements, added in the flank rubber, but are obtained by molding during the firing step. They are obtained in a manner similar to that of the sculptures made on the tread.

Figures 5, 6 and 7 can be used to visualize various examples of arrangement of the protuberances. In the example of Figure 5, the protuberances are arranged substantially radially. Figure 6 shows a variant of Figure 5 where the protuberances are arranged at an angle relative to the radial direction.

The clearance angle α is about 8 ° as shown in Figure 8. Such a clearance angle value allows a release of the tire after firing without deterioration of the final structure.

According to this embodiment, the protuberances have a ratio [sum of the widths of each protuberance in the circumferential direction on a radius / 2πR equal to 30%, at mid-height and have no angle with respect to the radial plane.

Figure 9A shows a three-dimensional representation of the radially outer portion 8a of the protuberances 8 and its enlargement in Figure 9B of Figure 9A. In these figures 9A and 9B, the portion 8a of each protrusion 8 and the recesses 9 are adjacent to a groove 10 disposed circumferentially on the surface of the tread 4 at its axially outermost end 4a. The groove 10 is not interrupted in its length.

According to this particular embodiment, the groove 10 has an axial width "I" along the axis YY 'which can be between 2 and 10 mm, and a radial height "h" along the axis ZZ' of between 3 and 8mm.

FIG. 10A also shows a three-dimensional representation of the radially outer portion 8a of the protuberances 8. Unlike FIGS. 9A and 9B, the groove 10 is interrupted. Indeed, the end 8a of the protuberances 8 and adjacent recesses 9 completely cut the groove 10 in the circumferential direction of the tire. FIG. 10B shows another variant of a three-dimensional representation of said radially outer portion 8a of the protuberances 8. In this figure, the protuberance 8 partially cuts the groove 10 in the circumferential direction of the tire.

Figures 1 1 A and 1 1 B show that the radially inner portion 8b (shown in dashed lines) of the protuberance 8 is spaced a thickness "d" of the radially inner portion 10b of the groove 10. This thickness " d "is less than 2 mm, and preferably less than 1 mm.

FIG. 12 illustrates an exemplary embodiment also illustrating the cables 1 1 disposed in the vicinity of the protuberances 1 1. In these examples, the cable has a diameter greater than 0.9 mm.

The tire according to the invention is obtained after baking and molding in a baking mold in a conventional manner.

Reference numbers used in figures Pneumatic for passenger vehicles

Carcass reinforcement

Reinforcement of general reference belt

Tread

a Axially outermost end of the tread

flanks

Rim

a circumferential reinforcement element

b Top of the rim hook

protuberances

a, 8b, 8c Extremity of the protuberances

Hollow

0 circumferential path

0b Radially inner part of the groove

1 Large diameter cables

Claims

1. A tire for a wheel assembly comprising a rim (7) having rim catch tops (7b), and a tire, said tire having at least one carcass reinforcement (2) provided with cables (1 1) radially surmounted externally a crown reinforcement (3), itself radially inside a tread (4) having two axially outermost ends, said crown reinforcement (3) consisting of at least one layer reinforcement elements, said tread (4) being connected to two beads (5) via two sidewalls (6), said beads (5) being intended to come into contact with a rim (7), each bead (5) having at least one circumferential reinforcing element, said sidewalls (6) having, on their outer surface, a series of alternating protuberances (8) with recesses (9), characterized in that each protuberance (8) is disposed on the surface of the sidewall (6) said protuberances (8) extending in a regular or irregular manner, and continuously, between a point A and a point E,

the position of the point A lying between R ₂ + 10mm and the intersection of the radially outer surface of the tread and the sidewall, and a radial axis ZZ 'distant from the equatorial plane AA' of a width L _A between ½ (L-60mm) and ½ (L-10mm), where L is the nominal flange size, and said point E being disposed, in a radius included in:

- R ₂ >RE> R _S + 0.2 (R ₂ - R _S ), R ₂ being the radius corresponding to the position of the top of the hook of a corresponding rim (7b) and R _S being the radius of the seat of the corresponding rim.

2. A tire according to claim 1, characterized in that said tread (4) comprises, at at least one axially outermost end (4a), a circumferential groove (10).

3. A tire according to claim 2, characterized in that at least one protrusion (8) interrupts partially or completely said circumferential groove (10).

4. A tire according to claim 2, characterized in that each protuberance is adjacent to the circumferential groove (10).

5. A tire according to claim 2, characterized in that at least two adjacent protuberances or not penetrate into said circumferential groove (10).

6. A tire according to one of claims 1 to 5, characterized in that the outer surface of the sidewall is between 0.2 and 2mm.

7. A tire according to one of claims 1 to 5, characterized in that the diameter of said cables (1 1) of the carcass reinforcement is greater than 1 mm.

8. A tire according to one of claims 1 to 5, characterized in that the cables (1 1) of said carcass reinforcement are hybrid cables.

9. A tire according to claim 8, characterized in that the cables (1 1) hybrids are aramid / nylon or aramid / PET.

10. A tire according to one of the preceding claims, characterized in that at least one protuberance (8) has a height and a length, said height being optimal in the center of said length of said protuberance.

1. A tire according to one of the preceding claims, characterized in that at least two protuberances (8) have a length different from each other.

12. A tire according to one of the preceding claims, characterized in that each protuberance (8) has a mean height H of between 3 and 10 mm and more preferably between 5 and 8 mm.

13. A tire according to one of the preceding claims, characterized in that each protuberance (8) has an average width of between 4 and 12 mm.

Tire according to one of the preceding claims, characterized in that each protuberance (8) has an average height greater than 80% of the maximum height over at least 80% of the distance between points A and E.

15. A tire according to one of the preceding claims, characterized in that each protuberance (8) has a draft angle of less than or equal to 20 °, and preferably between 5 and 8 °.

16. A tire according to one of the preceding claims, characterized in that two adjacent protuberances (8) are spaced from each other by an average distance less than or equal to 2 times the average width of a protuberance.

17. A tire according to one of the preceding claims, characterized in that two adjacent protuberances (8) are substantially parallel to each other.

18. A tire according to one of the preceding claims, characterized in that the protuberances (8) cover at least 40% of the total circumferential surface of the sidewall between points A and E.

19. A tire according to one of the preceding claims, characterized in that each protuberance (8), of definite geometric shape or any, comprises a neutral fiber, passing through a radially innermost end and a radially outermost end, and having an angle β, with respect to the radial direction ZZ ', of between -60 ° and + 60 °.

20. Tire according to one of the preceding claims, characterized in that the hollow (9) between two adjacent protuberances (8) extends axially in the extension of the hollow of a circumferential groove of the tread, passing through the point A, said groove being disposed on at least one axial end of the tread.

21. A tire according to one of the preceding claims, characterized in that two adjacent protuberances (8) form a recess between them which has an angle, with the circumferential direction between -15 ° and + 15 ° in a zone of the sidewall close to the point AT.

22. A tire according to one of the preceding claims, characterized in that it has a ratio [sum of the total widths of each protuberance in the circumferential direction over a radius Ρ] / 2πΡχ greater than or equal to 30%, and more preferably higher or equal to 60% and less than or equal to 70%, the widths of each protuberance (8) being defined at 50% of the total height of said protuberance (8) and the radius R of the tire being in the range R _E <R <R _a with R _a the radius of point A and R _E the radius of point E.

23. Mounted assembly comprising a rim and a tire as defined in one of the preceding claims.