CA1080099A

CA1080099A - Pneumatic tire

Info

Publication number: CA1080099A
Application number: CA298,750A
Authority: CA
Inventors: Norbert Zinnen
Original assignee: Uniroyal GmbH
Current assignee: Uniroyal GmbH
Priority date: 1977-03-25
Filing date: 1978-03-13
Publication date: 1980-06-24
Also published as: DE7709502U1

Abstract

Abstract A pneumatic radial tire having a reinforcing breaker between the carcass and the tread, the breaker comprising at least one folded ply comprising aramid cord members and the tire exhibiting a substantially better bond between the individual elements thereof.

Description

3(~9~ ~

The ;nvention relates to pneumatic tires, more particularly, for passenger cars, having a radial car-cass ancl a belt-lilce reinforcement arranged between the crown area of the carcass and the tread, the rein-forcement comprising at least one folded ply and at least one unfolded ply of cord material having rubber-coated cord elements arranged parallel to one another.
As used herein, the term "cords" is intended to include threads, filaments, yarns, wires, cables, bands, braids, and the like.
With regard to travel behavior and service life of pneumatic tires for passenger cars, such belted tires comprising a belt-like reinforcement made Otlt of two or more than two plies of steel cord . I . . .
; material have proved themselves with excellent results on a wide scale. However, it has been found that the : .
} steel cord materials for the tire building result also .: ~: .
in certain problems both with regard to manufacture l and with regard to the behavior of the steel cord under elevated stresses. -There are also known in the art belt-like re-, inforcements for pneumatic tires, which comprise a 1 plurality of plies and in which the edges of one un-, ....
folded cord ply are-hemmed in by the unfolded marginal areas of one or a plurality of strips of cord material in order to endow the belt-like reinforcement, in par-ticular under elevatied alternating loads and high peri pheral speeds~ with an improved bond.`
It is an object of the present invention to provide a new and improved pneumatic radial tire which ,: :: ~:

. .. .

11)8~0~

avoids one or more of the above-mentioned disadvant-ages of prior such tires.
It is another object oE the invention to pro-vid a new and improved pneumatic radial tire that, on the one hand~ retains the advantages of a belt ply made out of high-strength cord material while~ on the other, eliminating at the same time to a large extent the shortcomings of steel cord materials.
I have provided an unfolded steel cord ply or aramid cord ply and a folded cord ply made out of aramid cord elements, where the axial spacing of the folded edges of the folded cord ply corresponds sub-stantially to the axial width of the unfolded cord ply enclosed by the folded areas.
In this manner, the edges of the belt-like reinforcement are constltuted by a cord material con-taining aramid fibers, namely, the folded edges of said cord material. This cord material is optimally suited to hem in the edges of the unfolded cord ply and reliably to protect the elastomeric material of the tire against the action by the edges of the cord ply even at elevatèd stress and elevated peripheral speed~of the tlre. Moreover, in the event of an un- u-~
folded ply and cord eLements made out of steel, the folded~cord ply made out of aramid cord elements is cspabls of guaranteelng 5 considerably more fsvorabls transition between the properties of the steel cord elements a~d the balance of the tire building com-:
ponsnts. Moreover~ in the cass of ths new belt-like reinforcemsnt one achleves a considerable saving in ~:~;: .: ,'' .
': '~. ., `,~ 10~ 9 weight by comparison with rein~orcements made out of steel cord exclusively, without suffering any loss of the properties ~avorable ~or the belt-like rein~orcement thæt are known from high-strength cord.
On the basis o~ the novel belt-like rein~orcement one obtains a pneumatic tire that, particularly for elevated stresses, exhibits as a whole a substantially better bond between the in-dividual materials and elements used for the structure. As a result o~ the elevated retentivity Or the shape of the folded ply comprising the aramid cord elements, it becomes possible to manufacture the pneumatic tire with even greater accuracy ~
and dimensional stability. Although aramid fibers involve ~ -an organic ~iber, the capability of the new belt-like rein-forcement to withstand heat stresses is substantially greater than in the case of other organic cord materials that are customarily being used in lieu o~ steel cord for the manufacture of belt-like rein~orcements. --In accordance with the invention, a pneumatic radial tire has a radial carcass, a tread over the crown region of the carcass, and a rein~orcing breaker between the carcass and the tread. The breaker comprises at least one ~olded ply o~ cord material comprising cord members oriented parallel to one another and at least one un~olded ply o~ cord materlal comprising cord mem~ers oriented parallel to one another. The ~olded cord ply comprises aramid cord members, and the folded cord ply has folded edges with an axial spacing corresponding substantially to the axial width of the unfolded cord ply, and the ~olded cord ply has ~olded areas located asymmetrically ~ around the un~olded cord ply. :-¦~ 30 For a better understanding of the present invenkion, 1~ together with other and further objects thereo~, re~erence is .1~ . .
i ~ 3 9~
.
-3a-made to the ~ollowing description taken in connection with the accompanying drawings, and its scope will be pointed out in the appended claims.
Referring now to the drawings:
Fig. 1 represents a segment of a cross-section through the radial outer area of a pneumatic tire;
Fig. 2 constitutes a simplified schematic representation of an embodiment o~ the belt-like rein-forcement ~or the new pneumatic tire~ partially sho~n :' ~., .. ,~, . ..
-3a-:.

1(~ '3~ `

in cross section, in accordance with the invenkion:
Figs. 3 and 4 illustrate additional embodimen~s of the belt-lilce reinforcement;
Fig. 5 is a top view on the belt-like reinforce-ment in accordance with Fig. 4;
Fig. 6 represents another embodiment with re-gard to the belt-like reinforcement; and Fig. 7 and 8 show additional embodiments for the belt-like reinEoracement.
The pneumatic tire 1 shown in Fig. 1 as a seg-ment and cross-sectionally comprises in the customary manner a carcass 2, for example, a radial carcass, and a belt-like reinforcement 5 arranged between the crown area of the carcass 2 and the tread 3 of the tire.
In the example show~, the belt-like reinforcement rep-resented cross-sectionally is designed symmetrically with respect to the equatorial plane A of the tire~ I
The tread 3 is axially defined by the shoulder areas ~
: .: .
4 of the tire.

In the example illustrated, the belt-like rein-.
forcement 5 comprises an unfolded ply 6 and a folded ;
ply 7 both of which are made out of cord material. The unfolded cord ply 6 comprises steel cord elements oriented :: - -parallel to one another. The steel cord elements oriented paralleI to one another are, with respect to the equa-,' , ~ . .
torial plane A oriented substantially in circumferential direction and are capable of forming with the equatorial plane an angle between 10 and 30 degrees, preferably an 1 ~ . . . -angle between 18 degrees to 22 degrees.

The folded oord ply 7 comprises a strip of cord . : : .
:: .
~ .
', '' ' .
.` ' "''.
:~ :: .

`` ~Q~

material thatl by comparison with the cord material h, `
is of substantially greater width. The folded cord ply 7 comprises aramid fiber cord elements that are parallel to one another. The aramid cord clements that are parallel to one another are likewise oriented substantially in circumferential direction and can form an angle between 10 and 30 degrees, preferably from L8 to 26 degrees, with the equatorial plane A.
The angles respectively formed by the cord ele-ments of the plies 6 and 7 with the equatorial plane A
can be identical or different for both plies with the ;
orientation of the cord elements in their central areas being preferably opposite one another. The difference in angles between cord elements of the ply 6 and cord elements of the ply 7 can in absolute terms be between O degrees and 15 degrees with the angle formed with respect to the equatorial plane A being possibley 8reater in the case of the ply 6 or in that ~`~
: ' of the folded ply 7.
The edge areas of the folded ply 7 are folded over the edges of the unfolded ply 6 accompanied by the formation of folded areas 9 and 10 as a result o which, in the example illustrated. the central area 8 of the folded ply 7 comes to be radially situated in-side the unfolded steel cord ply 6. The cord elements of the ply 6 and those of the area 8 of the ply 7 do -, .:
therefore intersect whereas those of the folded areas :, 9 and 10 are oriented in the same direction as those of the area 8, preferably however3 at different angles.
In~Fig. 2, the axial overall width of the belt-,:

- - :
_5_ , 1~0~

like reinforcement 12 is designated by the letter B.
In this case as well it is assumed that the belt is built up symmetrically to the equatorial plane A.
The folded edges 15 and 16 formed by the folded ply 1~ have an axial spacing corresponding to the width B of the belt-like reinforcement 12. The unfolded steel cord ply 13 enclosed by the folded areas 18 and 19 of the folded ply 14 has a width S that is smaller ~-than the overall width B of the belt-like reinforce-ment by practially only about twice the thickness of the material of the folded ply 14. The axial width ~ ~-of the folded areas 18 and 19 is referenced in each case by the letters U and W. respectively.
In the case of the embodiments according to Figs. 1 and 2, the widths U and W of the two folded areas are identical. The width amounts in that case to preferably between 5 and 35% of the overall width B ; -~
of the belt-like reinforcement, that is, for each folded area 9, 10 and 18, 19, respectively.
The folded areas 18 and 19 of the belt 12 ac-cording to Fig. 2 can~ however~ have also a consider-ably greater width amounting in the case of each Eolded area to between about 50 and 60% of the overall width B - ~-~
of the belt 12. In the area of the lower boundary, the ~ , folded areas 18 and 19 are continuous or have free edges -which abut substantially in the equatorial plane A. In ~ -the area of the upper boundary there may be produced in ~ -the equatorial area a certain overlapping of the free edges of the folded areas 18 and 19.
The belt-like reinforcement can, as illustrated : : .:: : .

.
~ 6~

.

with the belt 22 oE Fig. 3, be formed also asymmetri~
cally with respect to the e~uatorial plane A. The asy~netry is achievecl preferably through differen-tial ~idths U and ~ of the two folded areas 26 and 27 of the Eolded ply 23. In this case as well, the free edges of the unfolded ply 24 are enclosed by the folded areas, ~le ~meven folded areas 26 and 27 are interconnected as a single piece by the central area 25 of the foled ply 23.
With regard to the belts 5, 12 and 22 it holds `
true, as an alternative, that the unfolded enclosed belt ply can likewise comprise aramid cord.
The belt-like reinforcement can, however, be built also out of more than two strips of cord material.
An embodiment for a three-part belt-like rein-forcement 32 is illustrated in Fig. 4. In this case~
there is provided one unfolded ply 33 corresponding to the ply 6 in Fig. 1 and one folded~ ply 33 corresponding to ,~j .

ing to the folded ply 7 of Fig. 1~ with the folded areas 36 and 37 respectively adjoining via the folded edges the central area 35 of the folded ply 34 corre-: ` :
sponding to the folded plies 10 and 9 of Fig. 1. The ., :
n~ olded areas 36~ 37 are situated at a substantial axial ` spacin& on either ~ide of the equatorial plane A. In the identical plane or at a diferent plane there is arranged, preferably centrally, a third strip of ma~
~, terial 38 comprlsing preEerably steel cord ma~erial.

The steel cord material has cord elements 41 oriented . .~
`; parallel to one another~ as represented in Fig~ 5, ~.
` which, by comparison with the cord elements 40 of the ~, : .
~ : :
~''`'~ '' unfolded ply 33 are slopecl in the opposite direction.While the cord elemnts 40 form with the equatorial plane an angle oE about 18 to 22 degrees, the cord elements 41 of the third ply 38 that is likewise un~
folded can form with the equatorial plane an angle between 15 and 90 degrees.
In the example illustrated in Figs. 4 and 5~
the cord elements 39 of the folded ply 34 in the foLded areas 36, 37 and the cord elements 40 o-f the unfolded ply 33 may have the identically large and identically oriented slope with respect to the equatorial plane.
Their angular deviation may amount to 0 to 15 degrees.
In the case of the embodiment according to Figs. 4 and 5~ both unfolded plies 33 and 38 may com-prise steel cord or aramid cord. The steel cord ply 38 may have any axial width between approximately 15 and 100% of the width S of the unfolded ply 33. If i the sum of the width of the unfolded ply 38 and of the two folded areas 36 and 37 is larger than the overall width B of the belt-like reinforcement, the folded `~
areas 36, 37 will overlap the free edges of the ply 38 namely on.the side of the ply 38 away from the ply i 33.

As an alternative9 the belt ply 38 may also comprise aramid cord or nylon cord with the last-men~
- ~; tioned one having a possible orien~tation of the cord angle up to about 0 degrees. ~-As illustrated in Fig. 6~ the folded ply can also comprise two separate strips oE material 45 and 49 arranged at an ~xial spacing on either side of the , :
:, . :
.,~ .
;.

.

:............... , ~ .. . ......
.. . ~ . . .. .

lQ~

equatorial plane l\. In that case, each strip of mater-ial forms a folded edge 46 and 50 and two folded areas 47, 48 and 5l, 52, respectively, ori~inating from said foldecl edges 46 and 50. In the example illustrated~
the two strips oE material 45 and 49 embrace respec-tively the free ed~es of two unfolded cord plies 43 and 44 with the latter one having a larger aY~ial width than the radially outer ply 43. In the case of each individual strip of material 45 to 49, the two per-tinent folded areas can have the identical or uneven axial width and the greater axial width can be situated either with the radially external or with the radially internal folded area. In that case, the belt-like rein-forcement can be designed symntetrically or asymmetrically to the equatorial plane with respect to the two folded strips 45 and 49, with the asymmetry redulting from dif-fere~ttial widths of the corresponding folded areas.

Preferably, however, the width of the folded areas 47, 48 and 51, 52, respectively, amounts between about 10 and 40% of the overall width B of the belt-like rein~
forcement~ 42. The belt ply 44 is preferQbly a steel cord ply, whereas the belt ply 43 can be either a steel cord ply, an aramid cord ply, or nylon cord ply"
~ As illustrated by Figs. 7 and 8, there can be 1 : , present also two folded belt plies 60, 61 and 70, 71 made out of aramid cord. The spacing b ought to be ., .

situated in the area of 15% of the width B and( the l~ spacing c ought to be sicuated within the area of ,~ .
10% of the width B. The plies are designed asymmet-~ ': ' ' ' ~ _9_ I~VO~

rically and are arranged situated inside one another.
In the Fig. 7 and 8 embodiments, the axial width of the inner folded ply is 80 percent up to approximately 100 percent of the width of the outer folded ply.

As cord elements for the folded plies there were used cords made out of aramid fiber, as has been mentioned already above. In that context, one uses preferably an aramid fiber available in the trade under the trademark Kevlar by the E. I. du Pont de Nemours and Company.
While there have been described what at pres- ;
ent are believed to be the preferred embodiments of this ~:
invention, it will be obvious to those skilled in the art that various changes and modifications may be made therein without departing from the invention, and it is, therefore, aimed to cover all such changes and modifications as fall within the troe spirit and scope of the invention~

. :

~' '' '~
~'':

-10- ~, :~ ' '''.

,", ,,' '' ~''

Claims

What is claimed is:

1. A pneumatic radial tire having a radial car-cass, a tread over the crown region of said carcass, and a reinforcing breaker between said carcass and said tread, said breaker comprising at least one folded ply of cord material comprising cord members oriented parallel to one another and at least one unfolded ply of cord material comprising cord members oriented parallel to one another, said folded cord ply comprising aramid cord members, said folded cord ply having folded edges with an axial spacing corresponding substantially to the axial width of said unfolded cord ply, said folded cord ply having folded areas located asymmetrically around said un-folded cord ply.