CN1833890A

CN1833890A - Heavy duty tire

Info

Publication number: CN1833890A
Application number: CN 200610065324
Authority: CN
Inventors: 丸冈清人
Original assignee: Sumitomo Rubber Industries Ltd
Current assignee: Sumitomo Rubber Industries Ltd
Priority date: 2005-03-18
Filing date: 2006-03-17
Publication date: 2006-09-20
Anticipated expiration: 2026-03-17
Also published as: JP2006256564A; CN100554008C; JP4473756B2

Abstract

The present invention relates to a heavy duty tire being capable of preventing positional shift of carcass cords in the blowout direction while restricting rupture of the carcass cords for improving bead durability. A ply turnup portions 6 b of a carcass 6 includes a sub-portion 11 that extends proximate of an upper surface SU of a bead core 5 in a tire radial direction upon inclining towards a ply main body portion 6 a and further includes an auxiliary cord layer 20 for pressing the sub-portion outside thereof in the radial direction. A bead portion 4 is further provided with a U-shaped bead reinforcing layer 15 . A periphery of the bead core 5 is coated by a reinforcing rubber layer 15 made of high elastic rubber having a complex elastic modulus E*a of 20 to 70 MPa, and a rubber thickness T 0 of a clearance portion G at which bead wires 5 w and carcass cords 20 are adjacent is defined to be not less than 0.7 mm while a cushion rubber layer 16 made of low elastic rubber layer 16 is interposed between the reinforcing rubber layer 15 and the carcass cords 20.

Description

Heavy duty tire

Technical field

The present invention relates to a kind of heavy duty tire, wherein also be limited in bead core distortion raising tyre bead durability of the bead part office of tyre bead winding-structure simultaneously by the explosion of restriction body cord.

Background technology

Shown in Fig. 9 (A), the casingply a general layout that constitutes tyre frame becomes will be arranged on crane span structure around the a2 of the portion that rolls of bead core b turnup on the both sides of the carcass plies main part a1 between bead core b, the b.For such as the improvement purpose that alleviates bead core weight etc., structure as Japanese Laid-Open Patent Application 11-321244 number disclosed heavy duty tire has now been proposed, wherein heavy duty tire adopts the casingply a that is made of the steel cord, shown in Fig. 9 (B), carcass plies is rolled the a2 of portion and is formed on carcass plies main part a1 place continuously, wherein, carcass plies is reeled a week substantially around bead core b.Such structure is called so-called " tyre bead winding-structure ", and this term also is used for this specification sheets.

In such structure, carcass plies is rolled the a2 of portion and is stopped around bead core b.Thus, its favourable part is when bead distortion, almost do not have stress on its terminal a2e, but actv. prevents infringement such as the loosening grade of the cord that is begun to produce by terminal a2e place thus.

Simultaneously, in such structure, carcass plies is rolled the a2 of portion and is reeled with less radius of curvature.Thus, very easily produce so-called resilience, that is, wherein body cord (steel cord) attempts to recover its initial difformity, and then the shape of body cord is tended to instability.Under the special situation during such resilience occurs in the crude tyre molding process, be easy to roll between a2 of portion and the bead core b and form the gap, and cause such as the defective of gas residue etc. molded at carcass plies.

On the other hand, in order securely carcass plies to be reeled around bead core b, in this " tyre bead winding-structure ", may make carcass plies roll the a2 of portion distortion by a device for molding.In this case, shown in Fig. 9 (B), carcass plies is rolled the a2 of portion constraint bead core b.By being applied to the tensile force F of body cord, produce very big torque M around bead core.This torque M causes the bead core distortion, makes around the tyre bead silk of bead core b and arranges disorderly (arranging skew).This also will make bight p and the contact pressure between the body cord on the tyre bead toe side of bead core b become big, cause making the wearing and tearing of cords break.

Particularly in this tyre bead winding-structure, because torque M, bead core b is out of shape on the direction of its kernel of section rotation at it.In order to suppress this rotational deformation, wish to realize the flattening of bead core.But the flattening of bead core will cause promoting that the distortion of tyre bead and worn-down produce.

Thus, propose to be pre-formed kink k at casingply a place for Japanese Laid-Open Patent Application 2001-246675 number and Japanese Laid-Open Patent Application 2000-219016 number by plastic deformation, wherein body cord is in the position in the bight that is suitable for bead core b part bending and molded, shown in Fig. 9 (C).But when the part of carrying out body cord molded (use mould part distortion), cord strength will reduce owing to the part bending, cause cord fracture early thus, and be difficult to guarantee sufficient tyre bead durability.

To this, Japanese Laid-Open Patent Application 2002-59716 number a kind of layout is disclosed, wherein the arranged outside enhancement Layer of rolling portion at carcass plies is used for preventing explosion by clamping the carcass plies portion of rolling.

Summary of the invention

An object of the present invention is to provide a kind of heavy duty tire, it can suppress the fracture of body cord and prevent body cord simultaneously in the long period explosion is to improve the tyre bead durability.

Another object of the present invention provides a kind of heavy duty tire, and it can suppress to arrange such as the tyre bead silk wearing and tearing of disorderly bead core distortion such as (arranging skew) and body cord, to improve the durability of tyre bead.

In order to reach goal of the invention, the invention provides a kind of heavy duty tire, it comprises:

The carcass plies main part; And

Casingply, it comprises that the carcass plies that continues in described carcass plies main part rolls portion,

Wherein, described carcass plies main part extend past sidewall portion is to the bead core of bead part, and the described carcass plies portion of rolling continues in described carcass plies main part and around described bead core and reel laterally from the tire axial inboard,

Wherein, each carcass plies portion of rolling all comprises along the principal part of the outer surface bending in the lower surface SL of the inside face of the tire axial inboard of bead core, tire radially inner side and the tire axial outside, reaches

Pair portion, it extends near the upper surface of the bead core of tire radial outside by the continuity of described principal part and towards the carcass plies main part,

Wherein, described carcass plies is rolled portion and is not formed local kink around described bead core turnup,

Wherein, be provided for suppressing the auxiliary cordline of described secondary portion at the tire radial outside of described secondary portion, described auxiliary cordline forms by on tire circumferential direction the steel cord being reeled around described secondary portion at least one week,

Wherein, described secondary portion is set to: the distance L a between the upper surface of its end and described bead core is limited in the scope of 1.0mm to 10mm, and on the direction of the upper surface that is parallel to described bead core, be not less than 5mm apart from d between the tire axial outer end of this end and bead core, and

Wherein, each bead part all is provided with the tyre bead enhancement Layer,

Described tyre bead enhancement Layer comprises curve, exterior part and inner component,

Described curve is rolled the principal part extension of portion and is positioned at its radially inner side along described carcass plies,

Described exterior part in the tire axial of the curve outside from described main portion from,

Described inner component extends in the tire axial inboard of curve,

Radial height Hi apart from the tyre bead baseline is defined as greater than the radial height Ho of exterior part apart from the tyre bead baseline with inner component, and simultaneous altitude Ho is not less than 25mm.

By above structure, can suppress resilience and can not produce the distortion of local kink or the local deformation of body cord thereupon.The explosion that can suppress body cord thus suppresses gas remnants or cords break simultaneously and the defective that causes is molded.

At this, secondary portion is not pressed on the top surface of bead core in the adhesion mode consumingly by auxiliary cordline.Arrange that with this bending degree of body cord can be alleviated, preventing the part bending of the body cord that auxiliary cordline causes, thereby can prevent the fracture of cord.

In addition, between secondary portion and bead core outside face, insert rubber, be used to guarantee that distance L a is in the scope of 1.0mm to 10mm.Be provided with this, the tension force by acting on when the squeegee action has prevented the offset of body cord on the explosion direction, and by the tyre bead enhancement Layer is set, has suppressed the offset of body cord, thereby realizes the improvement of tyre bead durability.

On the other hand, the invention provides a kind of heavy duty tire, it comprises:

The carcass plies main part; And

Wherein, described carcass plies main part extend past sidewall portion is to the bead core of bead part, and the described carcass plies portion of rolling continue in described carcass plies main part and around described bead core from the tire axial inboard turnup laterally,

Wherein, each described carcass plies portion of rolling all comprises the principal part of the outer surface bending in the lower surface SL of inside face along the tire axial inboard of bead core, tire radially inner side and the tire axial outside, and

Pair portion, it is by the continuity of described principal part and extending near the bead core upper surface of tire radial outside towards layer main body portion of described curtain portion inclination mode,

Wherein, described carcass plies is rolled portion and is not being formed local kink around described bead core turnup,

Wherein, be provided for suppressing the auxiliary cordline of this pair portion at the tire radial outside of described secondary portion,

Wherein, the periphery of described bead core is covered with the reinforcement rubber layer, and this reinforcement rubber layer comprises that thickness t a is 0.5mm to 3.0mm, complex elastic-modulus E ^*A is the high elastic rubber of 20MPa to 70MPa,

Wherein, the immediate adjacent position of body cord at the tyre bead silk and the described casingply of described bead core, the rubber thickness TO of the clearance portion between tyre bead silk and the body cord is not less than 0.7mm, and described clearance portion comprises the liner rubber layer between described reinforcement rubber layer and described body cord, this liner rubber layer is made by low elastic rubber, its complex elastic-modulus E ^*B is less than the complex elastic-modulus E of described reinforcement rubber layer ^*A, and its difference (E ^*A-E ^*B) be not less than 10MPa.

In the tyre bead winding-structure, the periphery of bead core reaches the reinforcement purpose by strengthening rubber layer coated with the high resiliency with specific thicknesses.Can limit thus such as tyre bead silk arrangement skew and wait the bead core distortion.In addition, close adjacent position between tyre bead silk and body cord guarantees that the rubber thickness TO (for example shown in Fig. 7 (A)) of the clearance portion between tyre bead silk and the body cord is not less than 0.7mm.By guaranteeing rubber thickness TO and strengthen rubber layer resultant effect therebetween and also can effectively suppress the wearing and tearing of body cord in that high resiliency is set, and can improve the tyre bead durability and also can expect to suppress simultaneously the bead core distortion.

At the liner rubber layer of strengthening further inserting between rubber layer and the body cord low elasticity.Arrange by this, can alleviate the explosion that distortion can also suppress body cord simultaneously.

Description of drawings

Fig. 1 shows the section drawing of an embodiment of heavy duty tire of the present invention;

Fig. 2 is the section drawing that its bead part is shown with the amplification form;

Fig. 3 is the section drawing that the principal part of bead part is shown with further amplification form;

Fig. 4 is shown specifically the section drawing that carcass plies is rolled portion;

Fig. 5 shows the section drawing of the principal part of another bead part;

Fig. 6 is the section drawing that is used to illustrate casingply;

Fig. 7 (A) illustrates the tyre bead silk of adjacent position and the section drawing of the clearance portion between the body cord with the amplification form, and Fig. 7 (B) is the section drawing that A-A along the line gets;

Fig. 8 (A) is that Fig. 8 (B) is the section drawing that A-A along the line gets with the section drawing of the adjacent portion of amplifying another embodiment of formal specification;

Fig. 9 (A), 9 (B) and 9 (C) are the section drawings that is used to illustrate existing bead part.

The specific embodiment

Below with reference to its example that illustrates explanation one embodiment of the invention.Fig. 1 is the explanation section drawing of heavy duty tire of the present invention under the inflating condition of 50kPa, and Fig. 2 and Fig. 3 are to amplify the section drawing of its bead part of formal specification.

At this, unless otherwise indicated, the dimension definitions of each parts of tire is under the venting condition of 50kPa---and be mounting of tyre to conventional wheel rim, fill the interior pressure of 50kPa and do not apply size under the situation of load on it.At this, term " conventional wheel rim " refer to according to comprise tire institute based on the standard system of standard be the wheel rim that each tire limited, it can be conventional wheel rim according to JATMA, according to " design wheel rim (design rim) " of TRA, and according to " measuring wheel rim (measuring rim) " of ETRTO.

In addition, term " tyre bead baseline BL " refer to by by tire based on the line along tire axial of rim diameter position of prescribed by standard.

In addition, complex elastic-modulus is by being 70 ℃ in temperature, and frequency is 10Hz, and initial strain is 10% and the value of dynamic strain for using visoelasticity spectrometer (viscoelasticityspectrometer) to measure under ± 1% the condition.

In Fig. 1, heavy duty tire 1 comprises the carcass 6 that extends until the bead core 5 of bead part 4 through sidewall portion 3 from fetus face 2, and is arranged in the radial outside of carcass 6, the bracing ply 7 in the fetus face 2.

Bracing ply 7 comprises and is no less than two, preferably is no less than three band bundle carcass pliess that adopt steel band bundle cords (steel cord).Present embodiment illustrates three layers structure, it comprises the first band bundle carcass plies 7A, the second bracing ply 7B and the 3rd bracing ply 7C, wherein the first bracing ply 7A is positioned at radially the most inboard, and its band bundle cord is arranged as the angle of 60 degree ± 15 degree with respect to the tire circumferential direction precedent, and the cord among the second bracing ply 7B and the 3rd bracing ply 7C becomes less angle to arrange with respect to tire circumferential direction, for example 10 to 35 degree.Because bracing ply 7 is arranged to be with bundle cord criss-cross in a carcass plies therein, play the effect that improves the band beam intensity and strengthen fetus face 2 by the hoop effect like this.

Carcass 6 is made of the casingply 6A that arranges to the angle of 90 degree as 80 degree with respect to the tire circumferential direction precedent.Casingply 6A comprises that a series of carcass plies rolls the 6b of portion, and it is along both sides layout of the carcass plies main part 6a that extends between bead core 5 and 5.Carcass plies is rolled the 6b of portion and is rolled laterally by the tire axial inboard.

With shown in the amplification form, bead core 5 is made of ring bodies as Fig. 2, and therein, for example steel tyre bead silk is wound into the form of multisectional multilayer row.Present embodiment shows the flat hex shape with the cross section of growing crosswise.At this, as required, the cross sectional shape of bead core 5 also can be regular hexagon or rectangle.In bead core 5, when from cross-section, comprise that the surface on the long limit of tire radially inner side is defined as the lower surface SL of bead core 5, and comprise that the surface on the long limit of tire radial outside is defined as the upper surface SU of bead core 5 with hexagonal section.In addition, will comprise the linear bending edge of polygon and be defined as the inside face Si of bead core 5 on the surface of inboard lower surface SL that connects bead core 5 of tire axial and upper surface SU.Surface on its opposite side of formation bending edge is defined as outside face So.

Lower surface SL be parallel to conventional wheel rim J wheel rim sheet J1 sheet surface and extend, in width range, strengthened the coordinate force of itself and wheel rim thus.Conventional wheel rim J is the tapering type wheel rims of tubeless 15 degree, and the lower surface SL of bead core 5 and upper surface SU are with respect to the angles of about 15 degree of the corresponding inclination of tire axle.At this, term " about 15 degree " is intended to allow manufacturing errors, refers to the scope of 15 degree ± 2 degree.

In this tyre bead winding-structure, because rolling the 6b of portion, carcass plies reels, so, will produce stronger torque around bead core by being applied to the tensile force on the body cord 20 around bead core 5.Thus, in bead core 5, tend to produce such as the arrangement skew of tyre bead silk 5w or arrange the core that subside (arranging disorderly) wait and be out of shape.The contact pressure that also may take place with body cord acts on the tyre bead toe of bead core 5 or the bight P1 of tyre bead heel side consumingly, the situation at P2 place, thus cause the wearing and tearing that may cause that body cord ruptures.

Further, because torque, bead core 5 is in easy deformation on the hand of rotation of its kernel of section.Thus, bead part 4 also can be out of shape from the direction that the wheel rim sheet lifts in the toe-end side, and this is disadvantageous aspect air-tightness.Need to limit this rotational deformation thus.

Thus, compared to prior art, the bead core 5 that is shown among Fig. 3 is more flat.Particularly, be not less than 1.7 with being defined as, preferably be not less than 2.0 at ratio WC/HC perpendicular to the core thickness HC on the direction of upper surface SU at the core width W C on the direction that is parallel to upper surface SU.By increasing the rotational deformation that the super flat structure that realizes than WC/HC will reduce bead core 5.Thus, can prevent that the toe side from being lifted by wheel rim sheet J1, thereby guarantee the air-tightness of wheel rim J.Here, because the too flat bending rigidity that will make reduces, and may cause the coordinate force deficiency of wheel rim J, so do not wish than WC/HC above 2.8.Particularly, be limited to than WC/HC in 1.7 to 2.8 or 1.7 to 2.5 the scope, thus, be limited in 0.4 to 0.6 the scope than HC/WC in the present embodiment.

In the present embodiment, holding layer 12 arranges around bead core 5.Holding layer 12 for example is made of the woven, the nonwoven fabrics that adopt organic fiber or the carcass plies that is furnished with the organic fiber silk.Because hold the outer surface that layer 12 has covered bead core 5, can prevent the direct contact of body cord and tyre bead silk, thus the damage of the body cord that can anti-attritionly cause.

In addition, bead part 4 is the tyre bead winding-structure, and wherein the carcass plies of carcass 6 is rolled the 6b of portion and passed through near the upper surface SU of bead core 5.

As shown in Figure 3, carcass plies is rolled the secondary portion 11 that the 6b of portion comprises that principal part 10 reaches by its continuity.Principal part 10 is along inside face Si, lower surface SL and outside face So bending.Pair portion 11 is by principal part 10 continuities and to extend towards the upper surface SU of carcass plies main part 6a bevelled mode near bead core.At this moment, carcass plies is rolled the 6b of portion does not have local bending, that is, they do not experience so-called molded (compressive strain).Therefore, they do not have to form the kink that obtains by plastic deformation.Like this, carcass plies is rolled the 6b of portion and is only comprised that elastic bending becomes the part of level and smooth arc, thereby prevents the deterioration of body cord intensity.

Here, secondary portion 11 refers to be positioned at the radially part of more lateral compared to the upper surface SU (or its extended surface) of bead core 5.Pair portion 11 tilts along its big more direction of approaching more terminal 11a of distance with respect to upper surface SU.Filled rubber 13 with general triangular cross section is arranged between secondary portion 11 and the upper surface SU (be arranged in the present embodiment, secondary portion 11 and hold between the layer 12).

In addition, in order to retrain secondary portion 11 and, to be formed for suppressing the auxiliary cordline 20 of this pair portion at the tire radial outside of secondary portion 11 in order to prevent the resilience of body cord.

Auxiliary cordline 20 is made of coiling body, and the auxiliary cord 20w of steel reels on the circumferencial direction of tire and is no less than a week in this coiling body.In preferred two to six weeks of screw winding, the banding effect of secondary portion 11 is strengthened.By this setting, can limit resilience and need not and carry out molded body cord.Can prevent deterioration in addition by the molded cord strength that causes.Can also stably secondary portion 11 be remained on desirable shape.

Auxiliary cord 20w preferably has the cord strength of 2000N to 4000N, and wherein, when less than 2000N, the quantity that then needs to increase the coiling cord is to produce sufficient banding effect, and this makes production capacity impaired.On the other hand, when surpassing 4000N, auxiliary cord 20w makes that with really up to the mark coiling work is difficult to carry out.Adopting wherein, periphery scribbles the gluing cord of topping rubber (topping rubber) in advance as auxiliary cord 20w.In this regard, if adopt organic fiber cord as auxiliary cord 20w, then owing to for example applied pressure and heat between curing time, the expansion that cord can be relatively large makes secondary portion 11 can not stably remain desirable shape.

But when adopting the auxiliary cordline 20 of this kind to strain secondary portion 11 with contact and when the upper surface SU of bead core 5 extends, the bending degree of body cord strengthens.By auxiliary cordline 20, in body cord, produce new part bending, for example, near the 5e of the tire axial outer end of bead core 5, thereby will be difficult to suppress reliably the fracture of cord.

For this reason, as mentioned above, arrange to have triangular shaped substantially filled rubber 13 in (in the present embodiment, in secondary portion 11 and hold between the layer 12) between secondary portion 11 and the upper surface SU.By such layout, secondary portion 11 is made as with respect to upper surface SU to become greater than 0 degree, preferably is not less than 10 degree, and the angle θ that more preferably is not less than 15 degree tilts.

By such layout, what the bending degree of body cord can be suitable alleviates, to prevent the fracture of cord reliably.This defective that has also suppressed gas residue of causing such as the resilience by body cord etc. is molded.In this regard, if angle θ is excessive, then auxiliary cordline 20 may slide and be shifted.This will weaken carcass plies and roll the engaging force of the 6b of portion and may cause taking place explosion.Thus, the upper limit of angle θ preferably is not more than 60 degree, further preferably is not more than 45 degree.

As shown in Figure 4, in this regard, angle θ is defined as the straight line of terminal 11a of connection (secondary portion 11) lower end position 11b and secondary portion 11 with respect to the formed angle of upper surface SU, wherein, at this lower end position 11b place, secondary portion 11 is crossing with the upper surface SU (or its extended surface) of bead core 5.For bead core 5, may take place that tyre bead silk 5w does not have linear rank but situation that in the vertical direction changes.At this moment, the upper surface SU of bead core 5 is rendered as non-planar surfaces.In this case, it is approximately tangent line K, and this tangent line K contacts tire axial outermost tyre bead silk 5wo and the most inboard tyre bead silk 5wi of tire axial in the tyre bead silk row that appear on the upper surface SU.

In addition, the distance L a of the terminal 11a from upper surface SU to secondary portion 11 is limited in the scope of 1.0mm to 10mm.In addition, also need being set at apart from d between the tire axial outer end 5e of terminal 11a and bead core 5 is not less than 5mm.This is a value on the direction of the upper surface SU that is parallel to bead core 5 apart from d.

This be because if distance L a greater than 10mm, then the stress during squeegee action will act on the terminal 11a of secondary portion 11 consumingly.Thus, 11a place generation infringement endways easily.If it is less than 1.0mm, then the bending degree of body cord just can not fully alleviate.Consider these factors, preferably the upper limit of distance L a is set to be not more than 7mm.If less than 5mm, then the carcass plies engaging force of rolling the 6b of portion will become insufficient apart from d.Therefore, as discussed, owing to the accumulation of braking heat etc. causes temperature to increase, the offset on the explosion direction will become greatly, cause body cord to become flexible thus.Like this, be defined as apart from d and make terminal 11a not contact carcass plies main part 6a, that is, terminal 11a greater than 0, and preferably is not less than 1.0mm apart from the distance L b of carcass plies main part 6a.

In this regard, auxiliary cordline 20 preferred arrangements are 1mm to 10mm for the distance L c along secondary portion 11 between the terminal 11a of its tire axial the inner and secondary portion 11, if wherein it is less than 1mm, then secondary portion 11 can break away from from auxiliary cordline 20, thereby can not realize the banding effect of auxiliary cordline 20.On the other hand, if it is greater than 10mm, the constrained force on the then terminal 11a side will become insufficient, make distance L a with apart from d with instability, under above two kinds of situations, all can not improve the durability of tyre bead.

In addition, filled rubber 13 is made of the rubber composition of the low elasticity that presents splendid impact and pressure relieve effect.The effect that this layout plays the distortion at the terminal 11a place that absorbs secondary portion 11 and prevents to damage.More specifically, complex elastic-modulus E ^*A is that the rubber composition of 5MPa to 15MPa is suitable.If complex elastic-modulus E ^*A is less than 5MPa, and then rubber is soft excessively, makes that the distortion of terminal 11a of secondary portion 11 is bigger.If it is greater than 15MPa, then the soft degree of filled rubber 13 is deficiency, makes to alleviate and absorbs the performance degradation that is out of shape.Consider these factors, preferably, with complex elastic-modulus E ^*The lower limit of a is set to be not less than 6MPa and preferably is not less than 7MPa, and higher limit is set to be not more than 13MPa and preferably is not more than 11MPa.Complex elastic-modulus is by being 70 ℃ in temperature, and frequency is 10Hz, and initial strain is 10%, and dynamic strain is to use the measured value of visoelasticity spectrometer under ± 1% the condition.

Specifically, under the accumulation of aforesaid braking heat etc. caused situation that temperature increases, it is big that the offset on the explosion direction is tended to become.In other words, will cause the loosening of body cord, make the thermal endurance performance deterioration of tyre bead.

For this reason, bead part 4 is formed with the tyre bead enhancement Layer 15 that takes the shape of the letter U substantially.Tyre bead enhancement Layer 15 is made of with respect to the cordline that the tire circumference line becomes 10 degree to arrange to the angles of 60 degree steel cord wherein, for example become 10 degree to 40 degree or 15 to spend to 60 degree, and, as shown in Figure 2, it comprises curve 15A, is positioned at the exterior part 15o in the curve 15A tire axial outside and the inner component 15i that is positioned at curve 15A tire axial inboard.Curve 15A in the face of and roll the principal part 10 of the 6b of portion and pass through along carcass plies at its radially inner side.Exterior part 15o separates and tilts and extend to radially outer to the tire axial outside from principal part 10.Inner component 15i extends along the tire axial inner surface of carcass plies main part 6a.

In this regard, the steel cord of the tyre bead enhancement Layer 15 body cord 6w that rolls the 6b of portion with respect to the direction of tilt of tire circumferential direction and carcass plies is different with respect to the direction of tilt of tire circumferential direction.Like this, because steel cord and body cord 20 intersect at curve 15A place,, improved inhibition effect thus to the rotational deformation of bead core 5 so rigidity is improved.

Here, when the heat by the braking accumulation of heat causes the excessive temperature of bead part 4 to increase,, make it tend to tyre bead toe side shifting because the rubber in the tyre bead that heat softens is pushed by applying loaded rim flange.Follow this to move, carcass plies roll the 6b of portion to the offset of explosion direction will become significantly, and then the heat durability of tyre bead is with deterioration.Exterior part 15o works to block rubber to tyre bead toe side shifting, has suppressed the offset on the explosion direction thus and has improved the heat durability of tyre bead.For this purpose, the radial height Ho of the outer end distance tyre bead baseline BL of exterior part 15o is defined as and is not less than 25mm.When its during less than 25mm, can not expect to obtain above-mentioned effect.

On the other hand, when load was applied thereto, inner component 15i worked to suppress bead part 4 and subsides.Particularly, its outer end is set to height H o greater than exterior part 15o apart from the radial height Hi of tyre bead baseline BL.Arrange that by this stress concentration at place, the outer end of parts 15o is minimized outside, effectively suppressed the damage at the place, outer end of parts 15o outside thus.For this purpose, guarantee that preferably diff-H (Hi-Ho) is not less than 3.0mm.In this regard, because by adjacency carcass plies main part 6a inner component 15i is protected, then as long as Hi＞Ho sets up, the stress that acts on its outer end damages thereby be difficult to generation in the outer end of inner component 15i less.

But as height H i, when Ho was excessive, the outer end of inner component 15i and exterior part 15o was with more approaching sidewall portion 3 one sides of bearing moderate finite deformation, and then easier generation damages.This also is unfavorable for expendable weight.The higher limit of preferred heights Hi is not more than 60mm thus, and the higher limit of height H o is not more than 40mm.

In this regard, arranged tyre bead triangular rubber core 16 at the radial outside of secondary portion 11, this tyre bead triangular rubber core 16 passes through carcass plies main part 6a and exterior part 15o in the convergent mode towards the extension of tire radial outside.In the present embodiment, tyre bead triangular rubber core 16 comprise the inboard glue core 16a that is arranged in the tire radially inner side and be arranged in its outside outside glue core 16b.In this regard, inboard glue core 16a and outside glue core 16b are separated towards carcass plies main part 6a bevelled boundary line j by the inner from secondary portion 11.

In the present embodiment, the complex elastic-modulus E of inboard glue core 16a ^*B is defined as and is not less than 20MPa.Be provided with this,, can bear by the upper surface SU of bead core 5 by the distortion that subsiding of carcass plies main part 6a caused when when it loads.In this regard, if complex elastic-modulus E ^*B surpasses 60MPa, and then the elasticity of this part will increase excessive.Because this will cause being out of shape near the outer end that concentrates on exterior part 15o, thereby cause damaging, so this is disadvantageous.Consider these factors, complex elastic-modulus E ^*The lower limit of b preferably is not less than 25MPa and the preferred 30MPa of being not less than, and higher limit preferably is not more than 50MPa and the preferred 40MPa of being not more than.

In addition, the complex elastic-modulus E of outside glue core 16b ^*C is less than the complex elastic-modulus of inboard glue core 16a, and complex elastic-modulus E ^*C preferably is not less than 3MPa and more preferably is not less than 3.5MPa.Higher limit expectation is not more than 7MPa and more preferably no more than 5MPa.As complex elastic-modulus E ^*C is during less than 3MPa, and the difference between the modulus of elasticity of inboard glue core 16a is with excessive, make and be easy to damage by producing near the j of boundary line, and on the other hand, when it surpasses 7MPa, the rigidity of whole bead part 4 is too high, is easy to produce near the outer end of outside glue core 16b damage, and this is undesirable.

In addition, Fig. 5 to 7 (A) and 7 (B) show an embodiment of another embodiment of the present invention, and Fig. 8 (A) and 8 (B) show another embodiment of this embodiment.Here, for the structure of specifically not illustrating at this, adopted the structure that is shown in the embodiment among Fig. 1 to 4.

This another embodiment is characterised in that and is used to suppress bead distortion or the following layout of worn-down (1) to (3).

(1) periphery of bead core 5 is covered with the reinforcement rubber layer of being made by high elastic rubber 15 (as shown in Figure 5).

(2) (be bight P1 in the present embodiment, P2), guarantee that rubber thickness TO (shown in Fig. 7 (A) and 7 (B)) is not less than 0.7mm in tyre bead silk 5w and body cord 20 immediate close position Q places.The rubber thickness TO at this close position Q place refers to the rubber thickness of the clearance portion G between tyre bead silk 5w and the body cord 20.

(3) the liner rubber layer of being made by low elastic rubber 16 (shown in Fig. 7 (A) and 7 (B)) is plugged in clearance portion G place and strengthens between rubber layer 15 and the body cord 20.

Strengthen rubber layer 15 by complex elastic-modulus E ^*A is that the high elastic rubber of 20MPa to 70MPa is made, and its thickness t a is limited in the scope of 0.5mm to 3.0mm.Here, thickness t a refers to each surperficial SU, SL, the thickness between the tangent line of Si and So.

Shown in Fig. 7 (A) and 7 (B), be defined as at the rubber thickness TO of the tyre bead silk 5w at close position Q place and the clearance portion G between the body cord 20 and be not less than 0.7mm.This rubber thickness TO is the value that comprises the thickness t a that strengthens rubber layer 15.

In addition, in clearance portion G place, strengthening plugging liner rubber layer 16 between rubber layer 15 and the body cord 20.This liner rubber layer 16 is made its complex elastic-modulus E by low elastic rubber ^*B is less than the complex elastic-modulus E that strengthens rubber layer 15 ^*A, and its difference (E ^*A-E ^*B) be not less than 10MPa.Present embodiment has illustrated that the rubber among the clearance portion G wherein is to comprise the situation of strengthening rubber layer 15 and the two-layer structure of liner rubber layer 16.In the present embodiment, form the topping rubber layer 22 formation liner rubber layer 16 of casingply 6A.

In this way, because being coated with, the periphery of bead core 5 has specific complex elastic-modulus E ^*The high resiliency of a and specific thicknesses ta is strengthened rubber layer 15 and is strengthened with it, so can effectively prevent such as the arrangement skew of tyre bead silk 5w and arrange the core that subsides etc. and be out of shape.In addition, at close position Q place, guarantee that the rubber thickness TO of clearance portion G is not less than 0.7mm.Guarantee rubber thickness TO and insert therein high resiliency strengthen the resultant effect of rubber layer 15 also will effectively suppress by with the wearing and tearing of the body cord that friction caused 20 of tyre bead silk, and when expectation suppresses the core distortion, can improve the tyre bead durability.

In this regard, hold layer 12 shown in also can the embodiment of application drawing 1 to 4, its thickness limits lessly.In this regard, holding layer 12 thickness is also included among the rubber thickness TO.In addition, filled rubber 13 is filled in to be formed at and strengthens rubber layer 15 and carcass plies and roll in another space between the 6b of portion.

At this moment, when only existing high resiliency to strengthen rubber layer 15 at clearance portion G place, can worry, when particularly shock load is applied to it, produce explosion at body cord 20 when when it loads.But, because low elasticity liner rubber layer 16 is inserted in clearance portion G place, thus distortion can be alleviated, and can prevent the explosion of body cord simultaneously.

In this regard, if complex elastic-modulus E ^*A is less than 20MPa, and thickness t a is less than 0.5mm, then to the reinforcement of bead core 5 and protection with too small, thus core distortion and worn-down are suppressed insufficient.In this regard, as rubber thickness TO during, worn-down is suppressed also with insufficient less than 0.7mm.On the other hand, as complex elastic-modulus E ^*B surpasses 70MPa, and strain concentrating is tending towards taking place the disadvantage of explosion in the time of will producing because of operation in periphery rubber place.When thickness t a surpasses 3.0mm, because of need use too much rubber, so will increase unnecessary cost.As difference (E ^*A-E ^*During b) less than 10MPa, the explosion of body cord also takes place easily.

Consider these factors, preferably with complex elastic-modulus E ^*The lower limit of a is set to be not less than 20MPa and its higher limit is set to be not more than 70MPa.Preferably the lower limit of thickness t a is set to be not less than 0.3mm and its higher limit is set to be not more than 3.0mm.Preferably, difference (E ^*A-E ^*B) lower limit is not less than 20MPa.Preferably, difference (E ^*A-E ^*B) the upper limit is not more than 60MPa, and when surpassing this value, strain will concentrate on the periphery rubber, makes to be easy to produce explosion.Thus, this difference is more preferably no more than 50MPa.Because above-mentioned reason, the higher limit of rubber thickness TO preferably is set to be not more than 2.0mm.Here, consider to prevent explosion that the thickness t b of liner rubber layer 16 preferably is not less than 0.1mm.

At this moment, stretch, between body cord 20 and bead core 5, acted on stronger pressure, will be difficult to guarantee that the rubber thickness TO at clearance portion G place is not less than 0.7mm owing to carry out the sulfuration of tyre vulcanization during molded.Thus, before tyre vulcanization is molded, preferably, strengthens rubber layer 15 at least and cure (also comprising semi-cure) corresponding to the part of close position Q.In this regard, be fit to use the method for the EBR irradiation conduct sulfuration (also comprising semi-cure) of adopting electron ray.Except this method, for example also can vulcanize by be under the coating state the whole reinforcement rubber layer 15 of heating at bead core 5.

Fig. 8 (A) and 8 (B) show another embodiment.Accompanying drawing illustrates rubber among the clearance portion G at close position Q place wherein and comprises three layers the example of being no less than of strengthening rubber layer 15 and liner rubber layer 16.In the present embodiment, the example of using three layers structure has been described.

More specifically, this three layers structure comprises the topping rubber layer 22 of strengthening rubber layer 15, casingply 6A and is formed on therebetween interlayer 23.Topping rubber layer 22 forms liner rubber 16.In the present embodiment, interlayer 23 covers the periphery of strengthening rubber layer 15.In addition, for the elastic difference that reduces 15 of topping rubber layer 22 and reinforcement rubber layers peels off to suppress interlayer, interlayer 23 further is arranged as its complex elastic-modulus E ^*E and complex elastic-modulus E ^*Difference (E between a ^*A-E ^*E) less than 10MPa.Based on needs, liner rubber layer 16 can be made of interlayer 23.In the case, the complex elastic-modulus E of topping rubber layer 22 ^*F and complex elastic-modulus E ^*Difference (the E of a ^*A-E ^*F) less than 10MPa.

Here, as difference (E ^*A-E ^*E) or difference (E ^*A-E ^*When f) being not less than 10MPa, can consider to work as E ^*B ≠ E ^*E and E ^*B ≠ E ^*When f set up, both constituted liner rubber layer 16 topping rubber layer 22 and interlayer 23.In other words, liner rubber layer 16 will be a two-layer stratigraphic structure at this moment.In this regard, when reinforcement rubber layer 15 is also in above-mentioned 20 to 70MPa scope, can adopt multilayer architecture.Tyre bead silk topping rubber layer can be arranged in yet and strengthen between rubber layer 15 and the tyre bead silk 5w, wherein the complex elastic-modulus of this tyre bead silk top rubber layer does not fall in above-mentioned 20 to 70MPa the scope.

Though concrete preferred implementation of the present invention has been described at present, and the present invention is not limited to illustrated embodiment, but can realize based on changing into it multi-form.

(example 1)

According to the parameter in the table 1, the heavy duty tire of making tire size and being 11R22.5 and have the basic structure among Fig. 1-3, wherein test and the tyre bead durability of each illustrated tire relatively mutually.Parameter beyond the table 1 is common.

In this regard, comparative example 1 has the structure shown in Fig. 9 (A), and wherein the carcass plies of carcass is rolled the outside face coiling of portion along tyre bead triangular rubber core rubber.Carcass plies roll portion apart from the tyre bead baseline height h be defined as 37mm.

(1) tyre bead durability

＜i〉the common durability of tyre bead

Used the drum type tester and tire is moved under the following conditions with the speed per hour of 20km/h, wherein wheel rim is 7.50 * 22.5, and interior pressure is 700KPa, and load is 26.72KN * 3, and has measured until the driving time that causes bead part to be damaged.With the driving timing definition of comparative example 1 is that 100 index is estimated.Numerical value is big more, and is favourable more.

＜ii〉the tyre bead heat durability

Above-mentioned tyre bead durability test is heated at wheel rim under 130 ℃ the condition and carries out, and is 100 index expression with the driving timing definition of comparative example 1 until the driving time that causes bead part to be damaged.

[table 1]

	Example 1	Example 2	Comparative example 1	Comparative example 2	Comparative example 3	Comparative example 4	Comparative example 5
	Example 1	Example 2	Comparative example 1	Comparative example 2	Comparative example 3	Comparative example 4	Comparative example 5	The bead structure carcass is molded＜kink〉and distance L a＜mm〉apart from d＜mm〉the auxiliary cord ply coiling quantity＜number of times of angle θ (degree)〉filled rubber complex elastic-modulus (MPa) tyre bead enhancement Layer height H i＜mm〉height H o＜mm〉the common durability tyre bead of tyre bead heat durability	Coiling Fig. 1-3 no 47 25 has 4 to have 7.0 to have 34 27 130 110	Coiling Fig. 1-3 no 97 45 has 4 to have 7.0 to have 34 27 105 110	Turnup Fig. 9 (A) is no-------have 45 27 100 100	Coiling Fig. 1-3 is that 47 25 nothings 4 have 7.0 to have 34 27 95 110	Coiling Fig. 1-3 no 11 7 52 has 4 to have 7.0 to have 34 27 95 95	Coiling Fig. 1-3 no 47 25 has 4 to have 7.0 to have 22 27 90 110	Coiling Fig. 1-3 no 43 50 has 4 to have 7.0 to have 34 27 95 95

From table, can determine that common durability of the tyre bead in the product of embodiment of the present invention and tyre bead heat durability both are improved.

(example 2)

Manufacture experimently the basic structure that has among Fig. 1 and Fig. 2 and Fig. 5 and the heavy duty tire (tire size 11R22.5) of the parameter in the table 2, and assessed tyre bead durability and core distortion.Parameter except the parameter in the table 2 is identical in operation.

(1) tyre bead durability

Used the drum type tester and tire is moved under the following conditions with the speed per hour of 20km/h, wherein wheel rim is 7.50 * 22.5, press in the standard to be 700KPa, and adopt three times of standard terminations (27.25KN * 3), and detected until the driving time that causes bead part to be damaged.With the driving timing definition of comparative example 1 is that 100 index is estimated.Numerical value is big more, and is favourable more.

(2) core distortion

After finishing durability test, tire is pulled down the distortion whether exist such as the arrangement skew of tyre bead silk or to arrange the bead core that subsides etc. to observe.

(3) explosion

After finishing durability test, tire is pulled down to observe whether have explosion.

[table 2]

	Comparative example 1	Comparative example 2	Comparative example 3	Comparative example 4	Example 1	Example 2	Example 3
	Comparative example 1	Comparative example 2	Comparative example 3	Comparative example 4	Example 1	Example 2	Example 3	Bead structure (figure .) is strengthened rubber layer complex elastic-modulus Ea＜MPa〉thickness t a＜mm〉rubber thickness TO＜mm〉liner rubber layer complex elastic-modulus Eb＜MPa〉(difference Ea-E*b)＜MPa〉thickness t b＜mm〉the auxiliary cord ply coiling quantity＜number of times of bead core ellipticity (HC/WC)〉tyre bead enhancement Layer height H i＜mm〉height H o＜mm〉tyre bead durability core distortion explosion	Coiling Fig. 9 (A) does not have--0.5 has 8.0-0.5 0.45 not have-have 55 27 100 nothings	Coiling Fig. 1; 2,5 have 8.0 1.0 1.5 to have 8.0 0 0.5 0.45 to have 4 to have 34 31 115 to have	Coiling Fig. 9 (A) has 15.0 1.0 1.5 to have 8.0 7.0 0.5 0.45 to have 4 to have 34 31 118 to have	Coiling Fig. 2 has 80.0 1.0 1.5 to have 8.0 72.0 0.5 0.45 to have 4 to have 34 31 110 nothings to have	Coiling Fig. 1; 2,5 have 50.0 1.0 1.5 to have 8.0 42.0 0.5 0.45 to have 4 to have 34 31 130 not have	Coiling Fig. 1; 2,5 have 25.0 1.0 1.5 to have 8.0 17.0 0.5 0.45 to have 4 to have 34 31 125 not have	Coiling Fig. 1,2 have 50.0 2.0 2.5 to have 8.0 42.0 0.5 0.45 to have 4 to have 34 31 140 not have

From table, can determine that the product of present embodiment can suppress the distortion of bead core, improve the tyre bead durability widely, and suppress the explosion of body cord simultaneously.

Claims

1. a heavy duty tire comprises

The carcass plies main part; And

Wherein, described carcass plies main part extends to the bead core of bead part through sidewall portion, and the described carcass plies portion of rolling continue in described carcass plies main part and around described bead core from the tire axial inboard turnup laterally,

Pair portion, it is by the continuity of described principal part and extending to towards carcass plies main part bevelled mode near the upper surface of the bead core of tire radial outside,

Wherein, described secondary portion is set to: the distance L a between the upper surface of its terminal and described bead core is limited in 1.0 millimeters to 10 millimeters the scope, and on the direction of the upper surface that is parallel to described bead core, be not less than 5 millimeters apart from d between the tire axial outer end of this end and bead core, and

Wherein, each bead part all is provided with the tyre bead enhancement Layer,

Described inner component extends in the tire axial inboard of curve,

Radial height Hi apart from the tyre bead baseline is defined as greater than the radial height Ho of exterior part apart from the tyre bead baseline with inner component, and height H o is not less than 25 millimeters.

2. heavy duty tire as claimed in claim 1, wherein

Described auxiliary cordline is by being provided with two to six weeks of steel cord coiling on tire circumferential direction.

3. heavy duty tire as claimed in claim 1 or 2, wherein

Described auxiliary cordline is arranged as, and is limited to along the inner distance L c to secondary portion end of the auxiliary cordline tire axial of this pair portion in 1 millimeter to 10 millimeters the scope.

4. as each described heavy duty tire in the claim 1 to 3, wherein

Described bead core is arranged as, and is parallel to core width W C on the direction of described outside face and is defined as perpendicular to the core thickness HC on the direction of described outside face 1.7 to 2.8 times.

5. heavy duty tire, it comprises

The carcass plies main part; And

Pair portion, it is by the continuity of described principal part and extending to towards layer main body portion of described curtain portion bevelled mode near the upper surface of the bead core of tire radial outside,

Wherein, the periphery of described bead core is covered with the reinforcement rubber layer, and this reinforcement rubber layer comprises that thickness t a is that 0.5 millimeter to 3.0 millimeters, complex elastic-modulus E*a are the high elastic rubber of 20 MPa to 70 MPas,

Wherein, the immediate adjacent position of body cord at the tyre bead silk and the described casingply of described bead core, the rubber thickness TO of the clearance portion between tyre bead silk and the body cord is not less than 0.7 millimeter, and described clearance portion comprises the liner rubber layer between described reinforcement rubber layer and described body cord, this liner rubber layer is made by low elastic rubber, its complex elastic-modulus E*b is less than the complex elastic-modulus E*a of described reinforcement rubber layer, and its difference (E*a-E*b) is not less than 10 MPas.

6. heavy duty tire as claimed in claim 5, wherein

At least a portion of described reinforcement rubber layer prevulcanization before tyre vulcanization is molded.

7. heavy duty tire as claimed in claim 5, wherein

Described bead core is arranged as, and is parallel to core width W C on the described outside face direction and is defined as perpendicular to the core thickness HC on the described outside face direction 1.67 to 2.5 times.

8. heavy duty tire as claimed in claim 5, wherein

Described liner rubber layer is the topping rubber layer that comprises described carcass layer.

9. heavy duty tire as claimed in claim 5, wherein

The described carcass plies portion of rolling comprises the auxiliary cordline of the tire radial outside that is positioned at described secondary portion, and it forms by on tire circumferential direction the steel cord being reeled around described secondary portion at least one week, in order to suppress described secondary portion.

10. heavy duty tire as claimed in claim 5, wherein

Described bead part comprises the tyre bead enhancement Layer,

Described tyre bead enhancement Layer has curve, exterior part and inner component,

Described exterior part in the tire axial of the described curve outside from described main portion from, and tilt and extend to radially outer to the tire axial outside, and

Described inner component extends in the tire axial inboard of described curve, and extends along the tire axial inner surface of described carcass plies main part.