CA1130711A - Pneumatic tires - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE
A pneumatic tire having a main body made of an elastic material and including a pair of bead portions, a pair of sidewalls and a tread between a pair of shoulders, and a rigid support ring provided in each of the bead portions. Cords which are not fixed to the bead portions are provided in the tread and disposed closer to the inner periphery of the tire in the form of a layer extending circumferentially of the tire. The cord layer is therefore freely movable with the tire main body. Each of the sidewalls between each end of the cord layer and the corresponding bead portion has an elastic deformable portion.

Description

11307~l TIT~E OF THE INVENTION
P~E~qATIC ~IRES

~ACKGROUND OF THE INVENTION
Vlith usual pneumatic tires, at least one layer of tire cords extends from bead to bead in the direction of radial section of the tire and is substantially fixed at its opposite ends to the beads, for examnle, by bein~
vround thereon. When such tires are inflated with air, the inflation pres~ure is supported by the cords and eventually by the beads.
Durin~ driving, the ~round contact portion, namely the tread, of the tire deforms to miti~ate impact for cushionin~. When a momentary impact acts on the tire, the tire deforms to produce an increase in the inflation pressure, which acts to reduce the deformation of the tire and therefore impede the absorption of the impact.
The reduction in the vol~e of the deformed portion of the tire due to the deformation is balanced ~0 by bul~in~ deformation of another portion of the sealed interior of the tire, for example, of sidewall w rtions, or by an increase in the inflation pressure. ~lith usual pneumatic tires having cords incorporated therein, the cords are of æmall elon~ation and extend fro~ bead - de, q~

~13(~711 to bead alon~ the direction of the radial section of the tire as substantially fixed thereto, so that the variation of the interior volume of the tire due to deformation is balanced by an increased inflation pre~sure because the beads restrain the other interior portion of the tire from bul~ing. This reduces the absorption of impact and impairs the cushionin~ ability of the tire.
Especially tires for agricultural, civil en~ineerin~ ~nd construction tractors, tillers and the like are inflated to a relatively low pressure of about 1.0 kt~/cm2, driven at a low speed o~ up to about 30 ~n/hour and used on irregu]ar surfaces. ~hen adapted to withstand impact by the increase oI' the inflation pressure, such tires have poor cushionin~ ability. Some pneumatic tires for passenger vehicles are used at an ai,r pressure of 0.1 to 0.3 kg/cm2 and have the same drawback.

SI~MARY OF THE INVENTION
~hereas convetional tire~ are based on the concept that the tire cords should extend from bead to bead as fixed to the bead~ at their opposite ends, the present invention, which has overthrown the conven-tional concept, relates to pneumatic tires ada~ted for

-2-- 113~3711 use at a lo~ inflation pressure for vehicles and including cords which are not fixed at their opposite ends to the beads so as to be movable relatively freely.
Stated more specifically, this invention provides a tubeless pneumatic tire having an annular main body made of an elastic material in its entirety and in-cluding a pair of bead portions, a pair of sidewalls, a pair of shoulders and a tread portion between the shoulders,.and a rigid support ring provided in each of the pair of bead portions, the tire being characterized by cords extending from one shoulder through the tread portion to the other shoulder in a radial section of the tire, the cords being positioned along and close to the inner surface of the tire in the form of at least one layer extending circumferentially of the tire, and by an elastic deformable portion positioned between each end of the cord layer and the corresponding bead portion and made only of the elastic material forming the tire main body, the elastic deformable portions bei.ng shaped symmetrically with. respect to the equator of the tire, the cord layer having the opposite ends thereof positioned at the boundaries between thc shoulders and the sidewalls substantially sy~l~etrically with respect to the e~uator.
An objcct of the invention is to provide a pneumatic ti~e which as incorporated therein tire cords having a length not extending from bead to bead and provided along and closer to the inner surface of the tire main body in the form of a layer extending circumferentially of the tire, the cord layer having Pg ~ ~ 3 ~

opposite ends positioned on the oppoiste sides of the equator of the tire axially away therefrom, the tire including a pair of elastic deformable portions between the bead portions and the opposite ends of the cord layer, so that when a momentary impact acts on the tire, the tire is capable of impeding the rise of its inflation pressure, permitting the elastic deformable portions to de~orm by bulging and thereby absorb the impact, the tire ~hus possessing outstanding cushionin~ ability althou~h retaining the desired rigidity.
Another object of the invention is to provide a pneumatic tire having incorporated therein tire cords which are provided closer to the inner surface of the tire main body over the circumference thereof to ~ive a uni~orm gauge thicknes9 to the tire and which are freely movable with the tire main body to effectively ~ive the desired rigidity to the tire and miti~ate shocks.
Another ob~ect of the invention i8 to provide a pneumatic tire o~ the construction described havin~
proper rigidity and hi~h cushionin~ properties by adju~ting the distance between each end of the cord layer and the corresponding bead portion, namely the len~th of the elastic deformable portion, the thickness of the deformable portion, and the hardness and strength of the elastic material used.

~307~

Another object of the invention is to provide a pneumatic tire of the foregoing construction in which a ri~id support rin~ is fitted in a circumferential groove formed in each of the pair of ~ead portions, so that when the tire is fitted to a rim and inflated with air, the bead portions are elastically deformed away from each other to fit to the rim completely hermetically by actin~ like a wedge.
Another object of the invention is to provide a pneumatic tire of the foregoing construction wherein the cord layer which is substantially not fixed to the bead portions has opposite ends positioned symmetrically with respect to the equator of the tire, and the elastic deformable portions are positioned and shaped symmetrically with respect to the equator of the tire to ~ive uniform rigidity to the tire in its entirety and render the tire equally deformable on its opposi~e sides, so that the tire retains proper ri~idity and miti~ates shocks even when cornering.
Another ob~ject of the invention i3 to provide a pneumatic tire of the foregoin~ type in which indenta-tions and pro~ection~ are formed on the inner side of the tire main body along which the cords are provided, with the cords enclosed in the projections and thereby arranged in a flexed form, whereby the tire is made ~130~
elastically deformable with ease.
Still another object of the invention is to provide a pneumatic tire of the type described in which diametrically inner and outer annular projections concentric with the axis of rotation of the tire are formed on the outer surface of the tire main body in corresponding relation to each end of the cord layer to give improved rigidity to the tire especially during cornering while assuring shock absorbing properties.
BRIEF DESCRIPTION OF THE DRAWINGS

. . . , _ Fig. 1 is a perspective view partly in section and showing part of the pneumatic tire of this invention schematical-ly;, Fig. 2 is a sectional view showing a first embodiment as fitted to a rim;
Figs. 3 (1), (2) and (3) are sectional views showing three examples the position of the end of a cord layer and an elastic deformable portion;
Fig. 4 is a plan view schematically showing an ar-rangement of tire cords;
Fig. 5 is a sectional view schematically showing a modified rigid support ring;
Fig. 6, appearing on the same sheet as Fig. 1, is a diagram in section showing part of the tire subjected to an inflation pressure;

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1~3071~

~i~. 7 is a sectional view showing a second embodiment fitted to a rim;
Fi~. 8 is a fragmentary sectional view showing the modified portion of Fi~. 7 in ~reater detail;
Figs. 9 (1) and ~2) are enlar~ed fra~mentary views showing two modifications of the inner surface of the tread;
~ig. 10 is a sectional view showing a third embodiment as fitted to a rim;
Fi~. 11 is a similar vie~r showing a fourth embodiment;
Fi~. 12 is a sectional view shov/in~ a tire for use on a. farm while bein~ driven strai~ht; and Fi~s. 13 (1), (2) and (3) are sectional views showin~ three tires during cornerin~ on a farm.

DESCRIPTION OF THE PREFERRED E~ODI~E~TS
Throughout the accompanyin~ drawin~, like part~3 are referred to by like reference numerals.
~ ith re~erence to Figs. 1 to 4, especinlly to Fi~. 2, a pneumatic ti.re i chiefly comprises a tire main bod,y 2, tire cords 3 and a pair of ri~id support rin~s 12, 13.
The tire main body 2 is toroidal nnd co~.prises a pair of bead portions 4, 5, a pair of sidewa.lls 6, 7, 1 ~ 3~ 7 11 a pair of shoulders8, 9 and a tread lO between the shoulders 8, 9. The tread lO is integrally formed on its outer peripheral surface with lateral lu~s 11.
The tire main body 2 is made entirely of rubber or an equivalently elastic material, such as synthetic rubber9 polyurethane or the like.
The support rings 12, 13 are provided in the pair of bead portions 4, 5 respectively. In the present embodiment, the ring comprises a steel wire. As seen in Fig. 2, the rings 12, 13 are fitted in circumferential grooves 15, 16 formed in the inner peripheries of the bead portions 4, 5.
The rin~s 12, 13 are ri~id and have substantially no elongation and may be made of metal, ri~id plastics or a comPosite material of fiber and plastics. ~he rigid support rin~ may be a bead core 14 embedded in the bead portion 4 as seen in Fig. 5 which shows only one of the rin~s.
The sidewalls 6, 7 have a pro~ressively increasing ~auge thickness toward the bead portlons 4, 5 and extend into these portions where they have the largest thiclmess. ~/~ith the ~rooves i5, 16 formed in the bead portions, ela5tically deformable protrusions 4A, 5A are formed.
~he shoulders 8, 9 between the pair of sidewalls ~13071~

6, 7 and the tread 10 are curved. Preferably the tread 10 and the pair of shoulders ~, 9 have a uniform ~auge thickness.
The cords 3 are provided substantially closer to the inner surface 1~ of the tire in the form of a layer extending circumferentially of the tire. The cord layer 3 has one end positioned away from the equator 0-0 of the tire axially thereof on one side of the equator. In the present embodiment, the end, indicated at 3A, is positi.oned approximately at the midportion o~
the shoulder 9. The other end 3B of the cord layer i~
positioned axially away from the equator 0-0 on the other side thereof, approximately at the mi.dportion of the other shoulder 8.
A ~ubstantially elastic covering layer 17A
which form~ the inner surface of the tire and along which the cord la~yer 3 i~ provided has approximately the same thickness as the cord l~yer 3 to cover the cord layer 3 to prevent d.amage to or break in the cord ln.yer as seen in Fi~s. 3 (1) to (3). The layer 17A al80 protects the cord layer 3 from the erosi.on or deteriora-tion due to the contact of the ballast liquid placed into the ti.re when it is used on the farm.
Examples of useful materials for the cords 3 are those having a small elongation, such as nylon, _g _ 113~ 711 polyester, rayon or like synthetic or artificial fiber, natural fiber, steel, aluminum or like metal, etc.
Such materia~s may be used in combination as a composite m~terial. These materials are used in the form of cords, monofilaments, tapes, loosely arranged cords or strips like a blind~ and thick fabric.
As seen in Fig. 4, the cords 3 are arranged at an an~le 0 of 0 to 15 degrees with respect to a line at ri~ht angles to the equator 0-0, whereby satisfactory ]0 cushioning properties are obtained. ~'~hen hi~her ri~idity or greater load-bearing capacity is needed, the an~le Q
can be 50 degrees, for example.
The tire cords 3 are provided in the form of a single layer as illustrated, or at least two superposed layers as desired. To assure good adhesion to the tire body, the cord layer i~ coated with rubber and cut to the desired shape ~or u~e.
As best seen in Fi~. 2, the cord l~ er 3, when seen in a radial section of the tire, ha3 a len~th not - 20 extendin~ ~rom bead to bead, preferably with its opposite ends 3A, 3R positioned symmetrically with re9pect to the equator 0-0. The cord layer i~ not fixed to the bead portions 4, 5, more specifically to the r-l~id support rings.
Since the cord ends 3A, 3~, irresrective of 113071~

whether or not they are positioned ~mmetrically with respect to the equator 0-0, are not fixed to the bead portions 4, 5, the side~alls 6, 7 include elastic deformable portions 18, 19 which are made of substantially the same material as the main body 2 and which are preferably positioned and shaped symmetrically with respect to the equator 0-0 as seen in Fi~. 2.
With reference to Figs. 3 (1) to (3), the rigidity and elastic deformation of the tire can be varied by alterin~ the height of the elastic deformable portions. Fig. 3 (1) shows the end 3~ po3itioned at the midportion of the shoulder 8. As the end extends toward the bead portion 4 as shown in Figs. 3 (2) and

(3), the tire has increasing ri~idity, while the len~th of the deformable portion 18 decreases. ~he ri~idity and the degree of elastic deformation are ~abiable also by alterin~ the gauge thickness of the deformable portion and the hardness thereof, ~ith the end 3B
located at the midportion of the shoulder 8.
Fi~. 7 to 9 (1) and (2) show a second embodi-ment. A~ seen in Fi~. 9 (1), indentations 20 and pro~ections 2] arranged alternately in paralle] to the equator are formed on the inner surface of the tire main body 2, that is, on the inner surfaces of the shoulders 8, 9 and the tread 10. Fi~. 9 (2) shows --11-- .

1~L30711 indentations 22 and projections 23 in the form of a honey-comb pattern~ Preferably the indentations 20 or 2~, and the projections 21 or 23 are arranged and shaped symmetricall~ with respect to the equator 0-0.
Vlith the second embodiment, the tire cords 3 extend alon~ the indentation~ and projections at least in the direction of the section of the tire and are enclosed in the projections 21 or 23 in a flexed form, so that the tire has lower rigidity than the first embodiment. Additionally the cords are prevented from bein~ disturbed in their arran~ement by the flow of rubber or like moldin~ material during production.
Fi~. 10 show~ a third embodiment of the invention, in which projections 11 integrally formed on the outer peripheral surface of the tread 10 are arran~ed in a large number both along the axis and along the equator of tke tire, as spaced apart from one another. Inner and outer annular ribs 25, 26 and 27, 28 concentric with the axis of rotation of the tire are formed on the outer surface of the tire at the boundarie~ between the 9idewalls 6,7 and the 6houlders 8, 9. In these features, the third embodiment differs from the first.
The third embodiment ha~ substantially the same performance as the first. Additionally, howe~er, ~hen the tire is somewhat flattened to contact the ~rolmd ~130711 over an increased area, for example, during cornering, the annular ribs 25, 26 or 27, 28 brace the tire to stabili7e the vehicle durin~ running.
Fig. 11 shows a fourth embodiment com.prisin~
the combina.tion of the second and third embodiments.
With either of the tires shown in ~igs. 10 and 11, the annular ribs 25, 26 and 27, 28 are positioned and shaped symmetrically with respect to the equator 0-0, preferably with the opposite ends 3A, 3~ of the cord layer 3 positioned at the locations of the ribs.
~ he pneumatic tires sho~m in Figs. 2, 7, 10 and 11 are supported on a rim 24 with the pair of bead portion~ 4, 5 fitted thereto. The rim 24 may comprise two segments. Drop-center rims and other know rims are also useful. Although not sho~n, the rim 24 is provided with a valve as means for injecting air into the tire.
~ hc pneumatic tires 1 of thi~ invention, whether or not havin~ a tube enclosed therein, are fitted to a rim 24 and inflated with a.ir through the unillustrated valve means to a relatively low pres9ure Por use in ofP-road vehicles adapted to travel on sa.nd, mud, snow or the like and also in a~ricultural vehicles.
V~ith the rigia support rin~s 12, 13 fitted in the grooves 15, 16, the protrusions 4A, 5A of the bead .

. -13-~13~

portions 4, 5 are elastically deformed away from each other by the inflation pressure to hold the su~port rin~s 12, 13. Since the support rings 12, 13 have a specified diameter and the rim 24 has inclined bead seats, the ~ead portions act like a wedge to hermetically fit to the rim 24.
At the portion of the tire having the cords 3 incorporated therein, i.e. the tread lO and shoulder9 8, 9, the cords 3 having almost no elongation withstand the inflation pressure P, while the elastic deformable portions 18, l9 without any cord stretch to withstand the pressure as seen in Fig. 6. Accordingly the tire has higher rigidity when the ends 3A, 3B of the cord layer are positioned closer to the bead portions 4, 5, whereas when there is a need to miti~ate momentary impacts, the cord ends 3A, 3~ are positioned mor~
remote from the bead portion~ 4, 5.
Figs. 12 and 13 (l) to (3) show three tires measuring 23 inches in out~ide diameter, lO.00 inches in width and lO inches in rim diameter and as used at an inflation pressure of 0.8 kg/cm2 under a load of 220 kg, while being driven straight and durin~ cornerin~, respectively. With the opposite ends 3A, 3~ of the cord layer 3 positioned closer to the bead portions 4, 5, the tire deforms less (see Fig. 13 (1)) during cornering, 1~3071~

whereas when the ends are away from the bead portions, the tire deforms more (see ~i~. 13 (2)). When the ends are positioned at an intermediate location (see Fi~. 13 (3)), the de,~ree of tire deformation is mediu~.
In any of these cases, the tire cords 3 afford the desired ri~idity to the tire during runnin~. Since the cord ends 3A, 3~ are not fixed to the bead portions

4, 5, with the elastic deformable portions 18, 19 provided between the ends and the bead portions 4, 5, the rise of the inflation pressure due to a momentary impact during driving (straight or along a corner) is impeded by the elastic deform~tion of the deformable portions 18, 19 to assure cushioning. The cord layer 3, which has opposite ends 3A, 3~ positioned on the opposite sides of the equator away therefrom, ~ives improved resistance to puncture. Since at least one of the ends 3A, 3B extends to the shoulder 8 or 9, preferably beyond the shoulder toward the bead portion. the cord layer 3 i~ movable relatively freely, affording the desired rigidity and proper cushionin~ properties. The cord layer 3,v~hich i5 provlded alon~ the tire inner surface 17 over the circumference thereof, ~erves to ~ive a uniform ~auge thickness and uniform ri~idity to the tire.

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Claims (5)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A tubeless pneumatic tire having an annular main body made of an elastic material in its entirety and including a pair of bead portions, a pair of sidewalls, a pair of shoulders and a tread portion between the shoulders, and a rigid support ring provided in each of the pair of bead portions, the tire being characterized by cords extending from one shoulder through the tread portion to the other shoulder in a radial section of the tire said cords being positioned along and close to the inner surface of the tire in the form of at least one layer extending circumferentially of the tire, and by an elastic deformable portion positioned between each end of the cord layer and the corresponding bead portion and made only of the elastic material forming the tire main body, the elastic deformable portions being shaped symmetrically with respect to the equator of the tire, the cord layer having the opposite ends thereof positioned at the boundaries between the shoulders and the sidewalls substantially symmetrically with respect to the equator.

2. A pneumatic tire as defined in claim 1 wherein the tread portion is formed on its inner side with indentations and projections spaced apart in the direction of the axis of rotation of the tire, and the cords extend along the indentations and projections and are en-closed in the projections.

3. A pneumatic tire as defined in claim 1 wherein each of the sidewalls has a progressively increasing gauge thickness toward the corresponding bead portion, and the rigid support ring is fitted in a circumferential groove formed in the bead portion.

4. A pneumatic tire as defined in claim 2 wherein the indentations and projections are positioned and shaped symmetrically with respect to the equator.

5. A pneumatic tire as defined in claim 1 or 4 wherein inner and outer annular ribs concentric with the axis of rotation of the tire are provided on the outer surface of the tire main body in corresponding relation to each end of the cord layer, and are shaped and positioned symmetrically with respect to the equator.