Description:PNEUMATIC LOW ANGLE STEEL BELTED TYRE FOR TWO WHEELED VEHICLE
FIELD OF INVENTION
The present invention relates to the field of pneumatic steel belted tyres in automotive vehicles. More particularly, the present invention relates to a pneumatic low angle steel belted tyre for two wheeled vehicle, which targets improvements in Tyre life, cornering performance, and Braking performance without changing the tread compound, rubber volume and Non-skid depth. Further, the present invention relates to a pneumatic low angle steel belt tyre for two wheeled vehicle, which significantly has reduction in number of tyre puncture. Advantageously, the pneumatic low angle steel belt tyre for two wheeled vehicle according to the present invention is applicable for both Radial and Bias construction.
BACKGROUND OF INVENTION
Generally, tyre is a highly engineered structural composite, predominantly made of rubber and rubberised stiffeners, to envelop the wheel rim and provide traction between the vehicle and the road. It also absorbs the shock by providing a cushioning effect. A conventional tyre comprises of 10 or more components including rubber compounds assembled into several parts such as tread, bead, sidewall, inner liner, ply, and belt. Conventional motorcycle or two wheeler radial tyre is made with fabric belt of nylon, polyester etc as shown in Figure 1 and high performance radial tyres are made with single layer of steel belt spirally wound (zero degree) over the carcass as shown in Figure 2.
Some of the prior arts to avert this are discussed below:
European Patent No. 0541368 B1 discloses a pneumatic radial tire for a two-wheeled vehicle, including a carcass (2) constituted by at least one carcass ply composed of cords extending at an angle of 75 to 90° with respect to an equatorial plane (X-X) of the tire, and a belt (4) constituted by at least two belt plies (4a, 4b). The belt plies are arranged radially outwardly on an outer peripheral side of a crown portion of the carcass, and are composed of cords extending substantially in the circumferential direction of the tire. The number of the cords per unit width of an outermost belt ply (4b) is in a range of 30% to 80% of that of a belt ply (4a) adjacent radially inwardly of the outermost belt ply as considered on average over the entire width of the belt.
U. S. Patent publication No. 2010024945 A discloses a pneumatic tire for a two-wheeled vehicle which has belt layer and tread section that are sequentially arranged on the outer side, in the radial direction of the tire, of a crown section of a carcass. On the belt layer is placed a spiral belt layer formed by spirally winding a band-like rubber coated cord layer so as to form a cord angle in the range of 0° to 5° relative to the circumferential direction of the tire. With L the tread surface distance from tire center CL to tread edge T, spiral belt layer is present only in the range of 0.65 L to 0.85 L from tire center CL, and intersecting belt layers are arranged in the range of from an edge in the lateral direction of the spiral belt layer to tread edge T. Intersecting belt layers include organic material fiber cords intersecting with each other and having a cord angle of from 30° to less than 75° relative to the circumferential direction of the tire.
JP 2018034787 A discloses a tire for an automatic motor cycle is provided with: a carcass extending from a tread part through side wall parts to bead cores of bead parts; and tread reinforcing layers arranged outside in a radial direction of the carcass and inside the tread part. The tread reinforcing layers are formed by winding lengthy belt-like plies having a plurality of reinforcing cords parallely pulled and coated with topping rubber around outside in a tire radial direction of the carcass spirally. Winding pitch of the belt-like plies 10 in a middle region Mi is smaller than winding pitch of the belt-like plies in a crown region Cr and winding pitch of the belt-like plies in a shoulder region Sh.
U. S. Patent publication No. 20030155056 A1 discloses a tire for a two-wheeled vehicle includes a carcass of toric form having a high transverse curvature, a tread band, and a circumferentially-inextensible belt structure. The belt structure is interposed between the carcass and the tread band, and includes reinforcing elements. Relative to an equatorial plane of the tire, the reinforcing elements may be randomly oriented, substantially oriented in an axial direction, or substantially oriented in an inclined direction. The belt structure further includes a radially-external layer provided with a plurality of cord coils disposed at a substantially-zero angle relative to the equatorial plane of the tire. The cord coils are positioned in axial side-by-side relationship and extend from one axial extremity of the belt structure to an opposite axial extremity. A density of the cord coils grows from the equatorial plane of the tire to the axial extremities of the belt structure.
None of the prior arts disclose a pneumatic steel belt tyre for two wheeled vehicle with two layers of low angle steel belts positioned diagonally with opposite lay, which targets improvements in Tyre life, cornering performance, puncture resistance and Braking performance without changing the tread compound, Rubber volume and Non-skid depth. Accordingly, there exists a need for a pneumatic steel belt tyre for two wheeled vehicle, which targets improvements in high speed cornering performance, tyre mileage, and Better braking distance and Puncture reduction.
The information disclosed in this background of disclosure section is only for enhancement of understanding of the general background of the invention and should not be taken as acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.
Further it will be apparent to those skilled in the art that the objects of this invention have been achieved by providing a pneumatic steel belt tyre for two wheeled vehicle, which is unique in nature unlike existing systems or the ones described in the above prior art in the field known to the inventors. Various changes may be made in and without departing from the concept of the invention. Additional features of the invention will be described hereinafter that form the subject of the claims of the invention. Those skilled in the art should appreciate that they can readily use the disclosed conception and specific embodiment as a basis for designing and modifying other methods and structures for carrying out the same purpose of the present invention. Further, features of some stages disclosed in this application may be employed with features of other stages. Therefore, the scope of the invention is to be determined by the terminology of the following claims and the legal equivalents thereof.
OBJECTS OF THE INVENTION
One or more problems of the conventional prior art may be overcome by various embodiments of the present invention.
It is the primary object of the present invention to provide a pneumatic low angle steel belted tyre for two wheeled vehicle, which targets improvements in Tyre life, cornering performance, puncture resistance and Braking performance without changing the tread compound, rubber volume and Non-skid depth.
Yet another object of the present invention is to provide a pneumatic low angle steel belt tyre for two wheeled vehicle, which significantly has better tyre life without changing tread compound, rubber volume of tread and non-skid depth.
Yet another object of the present invention is to provide a pneumatic low angle steel belt tyre for two wheeled vehicle, which improve high speed cornering performance without changing tread compound and rubber volume of tyre.
Yet another object of the present invention is to provide a pneumatic low angle steel belt tyre for two wheeled vehicle, which significantly has better braking distance without changing the tread compound and tread pattern design.
Yet another object of the present invention is to provide a pneumatic low angle steel belt tyre for two wheeled vehicle, which significantly has reduction in number of tyre puncture.
Yet another object of the present invention is to provide a pneumatic low angle steel belt tyre for two wheeled vehicle, which is applicable for both Radial and Bias construction.
These and other objects and advantages of the present subject matter will be apparent to a person skilled in the art after consideration of the following detailed description taken into consideration with accompanying drawings in which the preferred embodiment of the present subject matter are illustrated.

SUMMARY OF THE INVENTION
The following disclosure presents a simplified summary of the invention in order to provide a basic understanding of some aspects of the invention. This summary is not an extensive overview of the present invention. It is not intended to identify the key/critical elements of the invention or to delineate the scope of the invention. Its sole purpose is to present some concept of the invention in a simplified form as a prelude to a more detailed description of the invention presented later.

The present invention relates to a pneumatic low angle steel belted tyre for two wheeled vehicle, said pneumatic tyre comprising of:
a tyre casing having a tread portion disposed on the outermost surface, said tread portion contacts the ground during operation of the tyre;
a pair of low angle steel belts positioned below the tread portion diagonally and also with opposite lay;
a rubber strip interspersed between the first steel belt and second steel belt;
a body ply positioned below the first steel belt;
two spaced inextensible beads;
a pair of chafers;
a pair of apex;
a pair of sidewalls extending radially inward from the axial outer edges of said tread portion to join the two spaced inextensible beads, the axial outer edges of the tread portion defining a tread width; and
an inner liner positioned extending radially inward surrounding the body ply.

In the preferred embodiment of the present invention, the ratio of Shoulder drop (c) to Tread Cord Width (a) divided by the Aspect ratio (AR) of the tyre is in the range 0.502 to 0.630.

In the preferred embodiment of the present invention, the ratio of Tread Arc Radius 1 (TAR1) (e) to the Tread Cord Width (a) of the tyre is in the range 0.374 to 0.542.

In the preferred embodiment of the present invention, the ratio of Tread Arc Width (b) to the Shoulder drop (c) multiplied by the Aspect ratio (AR) of the tyre is in the range 1.80 to 2.60.

In the preferred embodiment of the present invention, the ratio of Tread Arc Width (b) to the Tread Arc radius 1 (e) divided by Aspect ratio (AR) of the tyre is in the range 2.00 to 2.57.

In the preferred embodiment of the present invention, the ratio of Shoulder Gauge (k) to Centre gauge (j) is in the range 0.85 to 1.1.

In the preferred embodiment of the present invention, the ratio of Apex height (i) to the Shoulder Drop is in the range 0.1 to 0.4.

In the preferred embodiment of the present invention, the ratio of Ply turn up height (h) to the Shoulder drop is in the range 0.1 to 0.6.

In the preferred embodiment of the present invention, breaking strength of the steel belt (2a, 2b) is in range 40 to 80.

In the preferred embodiment of the present invention, elongation at break of the steel belt (2a, 2b) is about 2 to 3 %.

In the preferred embodiment of the present invention, the steel belt Ends per Inch (EPI) is in range 16 to 30.

In the preferred embodiment of the present invention, the steel belt angle is in range 12 to 30 degree.

In the preferred embodiment of the present invention, number of filaments in the steel wires used in the steel belts is about 1 to 3.

In the preferred embodiment of the present invention, the pneumatic low angle steel belt tyre for two wheeled vehicle, has improvements to that of a regular conventional tyre in normal usage in tyre mileage, high speed cornering performance, and Better braking distance and Puncture reduction without changing the tread compound, Rubber volume and Non-skid depth.

BRIEF DESCRIPTION OF DRAWINGS
The advantages and features of the present invention will be more readily apparent by persons skilled in the art when considered in reference to the following description and when taken in conjunction with the accompanying drawings listed below.
Figure 1: Illustrates the transverse sectional view of the pneumatic nylon belt tyre for two wheeled vehicle according to the prior art.
Figure 2: Illustrates the transverse sectional view of the pneumatic spirally wound steel belt tyre for two wheeled vehicle according to the prior art.
Figure 3: Illustrates the transverse sectional view of the pneumatic low angle steel belt tyre for two wheeled vehicle according to the present invention.
Figure 4: Illustrates the graph showing subjective ride and handling performance parameters such as acceleration wobble, deceleration wobble, constant speed at smooth road, wheel hopping, ride comfort at rough road, steer response, cornering stability, slalom, comfort, and brake feel of the pneumatic low angle steel belt tyre for two wheeled vehicle in comparison to a regular tyre in normal usage.
Figure 5: Illustrates the nail bed arrangement for puncture resistance testing the pneumatic low angle steel belt tyre for two wheeled vehicle according to the present invention.
Figure 6: Illustrates the profiled second stage belt building drum used for building spirally wound steel belted tyre according to the prior art.
Figure 7: Illustrates the cylindrical second stage belt building drum used for building conventional tyre as used for building the pneumatic low angle steel belt tyre for two wheeled vehicle according to the present invention.
Figure 8: Illustrates the transverse sectional view of the pneumatic low angle steel belt bias tyre for two wheeled vehicle according to the present invention.

DETAILED DESCRIPTION OF THE INVENTION WITH REFERENCE TO THE DRAWINGS

The present invention as embodied by a "PNEUMATIC LOW ANGLE STEEL BELTED TYRE FOR TWO WHEELED VEHICLE" succinctly fulfills the above-mentioned need[s] in the art. The present invention has objective[s] arising as a result of the above-mentioned need[s], said objective[s] being enumerated below. In as much as the objective[s] of the present invention are enumerated, it will be obvious to a person skilled in the art that, the enumerated objective[s] are not exhaustive of the present invention in its entirety, and are enclosed solely for the purpose of illustration. Further, the present invention encloses within its scope and purview, any structural alternative[s] and/or any functional equivalent[s] even though, such structural alternative[s] and/or any functional equivalent[s] are not mentioned explicitly herein or elsewhere, in the present disclosure. The present invention therefore encompasses also, any improvisation[s]/modification[s] applied to the structural alternative[s]/functional alternative[s] within its scope and purview. The present invention may be embodied in other specific form[s] without departing from the essential attributes thereof.

Throughout this specification, the use of the word "comprise" and variations such as "comprises" and "comprising" may imply the inclusion of an element or elements not specifically recited.

The present invention is thus directed to pneumatic low angle steel belted tyre for two wheeled vehicle, which targets improvements in Tyre life, cornering performance, puncture resistance and Braking performance without changing the tread compound, rubber volume and Non-skid depth.

Referring to Figure 3, in an embodiment of the present invention, the pneumatic steel belted tyre for two wheeled vehicle, said pneumatic tyre comprising of: a tyre casing having a tread portion (1) disposed on the outermost surface, said tread portion (1) contacts the ground during operation of the tyre; a pair of steel belt (2a,2b) positioned below the tread portion (1) diagonally and also with opposite lay, a rubber strip (2c) interspersed between the first steel belt (2b) and second steel belt (2a); a body ply (3) positioned below the first steel belt (2b); two spaced inextensible beads (4a, 4b); a pair of chafers (5a, 5b); a pair of apex (6a, 6b); a pair of sidewalls (7a, 7b) extending radially inward from the axial outer edges of said tread portion (1) to join the two spaced inextensible beads (4a, 4b), the axial outer edges of the tread portion (1) defining a tread width; and an inner liner (8) positioned extending radially inward surrounding the body ply (3). The invention achieves the object in its unique design of a pair of low angle steel belts (2a, 2b) positioned below the tread portion (1) diagonally and also with opposite lay. This is achieved by significant changes to the technical aspects of the tyre. The shoulder drop the shoulder drop (SD)(c) is the vertical distance measured from the Outer Diameter point to the end point of the tread region (1) of the tyre as shown in figure 3. In the preferred embodiment of the present invention, the ratio of Shoulder drop (c) to Tread Cord Width (a) divided by the Aspect ratio (AR) of the tyre is in the range 0.502 to 0.630.

In the preferred embodiment of the present invention, Outer Diameter (OD)(d) is the overall diameter of the inflated tyre as shown in figure 3.

In the preferred embodiment of the present invention, the ratio of Tread Arc Radius 1 (TAR1) (e) to the Tread Cord Width (a) of the tyre is in the range 0.374 to 0.542.

In the preferred embodiment of the present invention, Tread Cord Width (TCW)(a) is the width of the tread region (1) of the tyre measured horizontally between the outermost points on the tread as shown in figure 3.

In the preferred embodiment of the present invention, Tread Arc radius 1 (TAR1)(e) which is the radius of the first curve on the tread region as shown in figure 3. This is the portion that is majorly in contact with the road surface. The Tread Arc radius 2 (TAR2)(f) is the radius of the second curve on the tread region as shown in figure 3, which comes into the footprint and plays a major role during cornering.

In the preferred embodiment of the present invention, the ratio of Tread Arc Width (b) to the Shoulder drop (c) multiplied by the Aspect ratio (AR) of the tyre is in the range 1.80 to 2.60.

In the preferred embodiment of the present invention, the Tread Arc Width (TAW)(b) is the curvilinear length of the tread region (1) of the tyre as shown in figure 3.

In the preferred embodiment of the present invention, the ratio of Tread Arc Width (b) to the Tread Arc radius 1 (e) divided by Aspect ratio (AR) of the tyre is in the range 2.00 to 2.57.
In the preferred embodiment of the present invention, the Aspect Ratio (AR) of the tyre is the ratio of Section Height (SH)(g) of the tyre to the Tread Cord Width (TCW)(a) of the tyre.

In the preferred embodiment of the present invention, the Section Height (SH)(g) of the tyre is the height of the tyre from the rim diameter or the height of the cut section of a tyre as shown in figure 3.

In the preferred embodiment of the present invention, the ratio of Shoulder Gauge (k) to Centre gauge (j) is in the range 0.85 to 1.1.

In the preferred embodiment of the present invention, the Shoulder gauge (SG)(k) is the combined gauge of the components of the tyre measured at the shoulder region of the tyre cut section as shown in figure 3.

In the preferred embodiment of the present invention, the Centre gauge (CG)(j) is the combined gauge of the components of the tyre measured at the centre of the tyre cut section as shown in figure 3.

In the preferred embodiment of the present invention, the ratio of Apex height (i) to the Shoulder Drop is in the range 0.1 to 0.4.

In the preferred embodiment of the present invention, the Apex height (AH)(i) is the distance between the Tyre heel point (Heel - Portion at which the tyre contacts the rim) to the end point of the Apex as shown in figure 3.

In the preferred embodiment of the present invention, the ratio of Ply turn up height (h) to the Shoulder drop is in the range 0.1 to 0.6.

In the preferred embodiment of the present invention, the Ply turn up height (PTUH)(h) is the distance between the Tyre heel point to the end point of the ply (3) after the turn up as shown in figure 3.

In the preferred embodiment of the present invention, breaking strength of the steel belt (2a, 2b) is in range 40 to 80.

In the preferred embodiment of the present invention, elongation at break of the steel belt (2a, 2b) is about 2 to 3 %.

In the preferred embodiment of the present invention, the steel belt (2a, 2b) Ends per Inch (EPI) is in range 16 to 30.

In the preferred embodiment of the present invention, steel belt (2a, 2b) angle is in range 12 to 30 degree.

In the preferred embodiment of the present invention, the steel belt (2a, 2b) angle is the angle at which the cords or wires in the steel belt (2a, 2b) are oriented relative to the circumferential direction of the tyre.

In the preferred embodiment of the present invention, number of filaments in the steel wires used in the belts (2a, 2b) is about 1 to 3.

In the preferred embodiment of the present invention, the pneumatic steel belt tyre for two wheeled vehicle, has improvements to that of a regular conventional tyre in normal usage in tyre life, cornering performance, puncture resistance and Braking performance without changing the tread compound, rubber volume and Non-skid depth.

In the preferred embodiment of the present invention, the performance improvements achieved with tyre made of two layers of Low angle steel belt (2a, 2b) by primarily optimizing tyre/Mould shape (1), tyre construction (2), suitable belt material (3), Belt dimensions (4) and also combination of the above mentioned 4 points.

Referring to Figure 8, in an another embodiment of the present invention, the pneumatic steel belted bias tyre for two wheeled vehicle, said pneumatic tyre comprising of: a tyre casing having a tread portion (1) disposed on the outermost surface, said tread portion (1) contacts the ground during operation of the tyre; a pair of steel belt (2a,2b) positioned below the tread portion (1) diagonally and also with opposite lay, a body plies (3a, 3b) positioned below the first steel belt (2b); two spaced inextensible beads (4a, 4b); a pair of chafers (5a, 5b); a pair of apex (6a, 6b); a pair of sidewalls (7a, 7b) extending radially inward from the axial outer edges of said tread portion (1) to join the two spaced inextensible beads (4a, 4b), the axial outer edges of the tread portion (1) defining a tread width; and an inner liner (8) positioned extending radially inward surrounding the body ply (3a, 3b). The invention achieves the object in its unique design of a pair of low angle steel belts (2a, 2b) positioned below the tread portion (1) diagonally and also with opposite lay. This is achieved by significant changes to the technical aspects of the tyre. The shoulder drop the shoulder drop (SD)(c) is the vertical distance measured from the Outer Diameter point to the end point of the tread region (1) of the tyre as shown in figure 7. In the preferred embodiment of the present invention, the ratio of Shoulder drop (c) to Tread Cord Width (a) divided by the Aspect ratio (AR) of the tyre is in the range 0.502 to 0.630.

For illustration,
Example 1
The pneumatic steel belt tyre for two wheeled vehicle was made as per the illustration in the figures 3 and 8. The pneumatic low angle steel belted tyre according to present invention, having the tyre/mould shape as given below compared to a conventional nylon belted tyre, will have significant improvement in tyre mileage, cornering performance, puncture resistance and braking performance.
• The ratio of Shoulder drop (c) to Tread Cord Width (a) divided by the Aspect ratio (AR) of the tyre is in the range 0.502 to 0.630 whereas a conventional nylon belted tyre has the ratio 0.35.
• The ratio of Tread Arc Radius 1 (e) to the Tread Cord Width (a) of the tyre is in the range 0.374 to 0.542 whereas a conventional nylon belted tyre has the ratio 0.708.
• The ratio of Tread Arc Width (b) to the Shoulder drop (c) multiplied by the Aspect ratio (AR) of the tyre is in the range 1.80 to 2.60 whereas a conventional nylon belted tyre has the ratio 3.14.
• The ratio of Tread Arc Width (b) to the Tread Arc radius 1 (e) divided by the Aspect ratio (AR) of the tyre is in the range 3.75 to 5.00 whereas a conventional nylon belted tyre has the ratio 2.6.
• The ratio of Tread Arc Radius 1 (e) to the Shoulder drop (c) divided by the Aspect ratio (AR) of the tyre is in the range 2.00 to 2.57 whereas a conventional nylon belted tyre has the ratio 0.9.
In all the cases Aspect ratio (AR) is taken as the Nominal Aspect ratio mentioned on the Sidewall of the tyre divided by 100.

A low angle steel belted tyre shown in Figure 3 and 8 according to present invention, having the tyre architecture as given below compared to a conventional nylon belted tyre, will have significant improvement in tyre mileage, cornering performance, puncture resistance and braking performance.
• The ratio of Shoulder Gauge (k) to Centre gauge (j) is in the range 0.85 to 1.1, whereas a conventional nylon belted tyre has the ratio >1.40
• The ratio of Apex height (i) to the Shoulder Drop (c) is in the range 0.1 to 0.4, whereas a conventional nylon belted tyre has the ratio >0.8
• The ratio of Ply turn up height (h) to the Shoulder drop (c) is in the range 0.1 to 0.6, whereas a conventional nylon belted tyre has the ratio >0.7

Selection of belt wire and Belt dimensions were finalized based on different test results.
• Belt material used in a Low angle steel belted tyre is Steel whereas a conventional tyre uses Nylon belt.
• Breaking Strength of a typical Steel belt is in range 40 to 80 whereas for a typical Nylon belt, it is in the range 14 to 23.
• Elongation at break of a typical steel belt is about 2 to 3 % whereas for a Nylon belt, it is about 18%.
• A minimum of 2 belts are present in most cases in both the conventional nylon belted tyre and the low angle steel belted tyre.
• Belt EPI in a Steel belted tyre is in range 16 to 30 whereas in a conventional nylon belted tyre, it is in the range 16 to 27.
• Belt angle in a Steel belted tyre is in range 12 to 30 whereas in a conventional nylon belted tyre, it is in the range 16 to 25.
• The No. of filaments in a steel wire used in the belt is about 1 to 3.

In the tyre size, 140/60 R17, one tyre made with conventional tyre shape, architecture and nylon belt was compared with another tyre made according to the present invention with the arrived set of values for cavity / tyre parameters and tyre architecture and selection of steel belt material and dimension as given in the Table 1. Such a tyre made according to the present invention shows significant improvement in tyre mileage, cornering performance, puncture resistance and braking performance.

Test Results: (Performance Index)
Tyre meets all BIS regulatory tests includes high speed, Endurance, Plunger etc.
Table- 1

Sl.no Description Conventional Nylon belted Tyre
(Control) Low angle Steel belted tyre.
(Trial)
1 Tyre Mileage Index 100 140
2 Cornering performance index
(Objective Measurement ) 100 140
3 Cornering performance Subjective rating 6.5 7
4 Cornering performance –Subjective rating Normalized to 100 for control tyre
100
108
5 Dry braking distance index 100 110
6 Wet braking distance index 100 104
7 Number of puncture -Index (Customized puncture test) 100 25
8 Cycle time /Tyre index 100 100

Puncture resistance Test
Puncture resistance test was conducted on the pneumatic low angle steel belted tyre according to present invention, as shown in Figure 3 and 8 and compared to a conventional nylon belted tyre as shown in Figure 1 and conventional spirally wound steel belted tyre as shown in Figure 2.

The puncture resistance test was done in track, where 1 inch length nails were arranged in an orderly manner in the track in multiple rows to form the nail bed as shown in Figure 5. 0.5 inch of gap was maintained between the nails. 2 inch of gap was maintained between each row of nails. 24 such rows of nails were arranged. The vehicle was run for about 5 times on the nail bed at a speed of 60 kmph and the number of nails that penetrated the tyre after each run was counted. The result showed, the low angle steel belted tyre as shown in Figure 3 and 8 has significant reduction in the number of nail penetration when compared with both the fabric nylon belted tyre as shown in Figure 1 and the spirally wound steel belted tyre as shown in Figure 2.

Thus, Comparing puncture resistance of the three tyres namely the conventional nylon belted tyre as shown in Figure 1, the spirally wound steel belted tyre as shown in Figure 2 and the low angle steel belted tyre according to present invention as shown in Figure 3 and 8, the said low angle steel belted tyre showed significant improvement in puncture resistance. This is due to the fact that the low angle steel belted tyre according to present invention has less resistance to nail penetration. Also, the low angle steel belted tyre according to present invention as shown in Figure 3 and 8 has two steel belts with cords running at an opposite angles forming a mesh like structure reducing and in some cases preventing the nails to penetrate into the tyre. Whereas the spirally wound steel belted tyre as shown in Figure 2 has only one layer of steel belt. Also, while comparing the steel cords per unit area of the tyre, the low angle steel belted tyre according to present invention as shown in Figure 3 and 8 has significantly higher no. of cords contributed by the two belt layers whereas the spirally wound tyre as shown in Figure 2 has only one layer of belt translating to less number of cords per unit area.

Major advantages of the pneumatic low angle steel belted tyre according to present invention when compared to conventional nylon belted tyre from the Table- 1 are as follows;
1. Tyre life significantly better than control tyre without changing tread compound and tread rubber volume.
2. Cornering performance found significantly better than control tyre.
3. Significant improvement in Dry and Wet braking performance without changing tread compound.
4. Significant reduction in tyre puncture.

Thus, from the graph as shown in Figure 4 and Table-1, subjective ride and handling performance parameters such as acceleration wobble, deceleration wobble, constant speed at smooth road, wheel hopping, steer response, cornering stability, slalom, brake feel are significantly better in Low angle steel belted tyres. It also has significant reduction in number of tyre puncture when compared to that of a regular conventional nylon belted tyre in normal usage.

Example 2:
Tyre build process of the pneumatic low angle steel belt tyre as shown in Figure 3 and 8 is compared with conventional tyre building and spirally wound steel belted tyre building process are illustrated below.

A conventional Fabric radial tyre building machine consists of two stages. The Inner liner is calendared to required width and thickness. The fabric roll with cords running parallel to the length of the roll is calendared with rubber and then cut at angles and joined again as required to form the ply and the belt with cords running at an angle to the length of the roll. The tread and sidewall are extruded to required profile. The Rubber coated steel wires are wound at required diameter to form the Bead. Tyre building drum is the major component. A conventional building drum as shown in Figure 7 is cylindrical in shape. The drum can be expanded and collapsed (i.e. Diameter of the drum can be changed). Initially the drum is in the collapsed state. The components Inner liner, chafer and the two plies are applied over the drum. Then the Beads are applied. The drum is expanded. Then the plies are turned up over the Beads and stitched. Then the sidewall is applied on the assembly and stitched. The assembly is called the 1st stage Green tyre. The 2nd stage is built on another drum called the belt building drum which is also cylindrical in shape and having a higher diameter than the 1st stage drum. Nylon belts are applied on the drum. Then the tread is applied over them. Then the integration of the two stages is done. The 1st stage Green tyre is put over an inflatable drum and is inflated. The OD of the Green tyre increases with the beads coming closer to each other. The 2nd stage is applied on the 1st stage Green tyre and is stitched over it. This assembly is the Green tyre. The green tyre is then put in the mould. A bladder expands inside the green tyre and pushes it to the mould. The green tyre grows. Heat is supplied to the tyre from both the bladder and the mould. The green tyre acquires the profile of the mould and is cured and will give the cured tyre.

The low angle steel belted tyre as shown in Figure 3 and 8 according to the present invention follows the same procedure as that of a conventional tyre building as shown in Figure 7. The belt is Steel instead of Nylon. Multiple steel wires coming from let off are arranged parallel to each other and they are calendared together with rubber. Then the calendared component is cut at angles to the length of the roll and joined together again at the cut angles to form the belt roll with steel wires running at an angle to the length of the roll. The belt roll is applied on the 2nd stage building drum (Cylindrical). 2 such belts (2a, 2b) with opposite lay angles are applied and then the tread is applied. Then this package (the belt package) is transferred to put on an inflated 1st stage Green tyre and stitched over it to form the Green tyre. Some additional components such as the rubber strip (2c) is applied between the belts (2a, 2b) to ensure integrity of the tyre.

In conventional Spiral steel wire winding as shown in Figure 6 in spirally wound steel belted tyre as shown in Figure 2, the 1st stage follows the same procedure as the conventional tyre building process. After completion of the 1st stage building, the 1st stage Green tyre is applied on another drum which is a profiled drum. The profiled drum is not cylindrical and has a profile very close to the profile of the cured tyre which is to be made. Then a single rubber coated steel wire or a strip containing 2 or 3 rubber coated steel wires is wound over the 1st stage Green tyre. Over that the tread is applied and stitched. This stage completes the Green tyre.

The main advantage of conventional tyre building machine is that the 2nd stage belt building drum as shown in Figure 7 is cylindrical and tyres of variable sizes and profiles can be made with the same drum. In the case of spiral wound steel wire for building spirally wound steel belted tyre as shown in Figure 2, the steel wire is applied over the 1st stage Green tyre on a profiled drum. The profile is specific to the particular tyre profile. Different profiled drums are required for making tyres of different sizes or profiles. In terms of productivity, the conventional tyre building methodology is predominant as previously calendered belt can be simply applied on the drum in building process whereas in spiral steel wire winding, single wire or a strip of steel wires is to be wound over the Green tyre and many turns are required to complete a single Green tyre. Comparing the building cycle time of the tyres, the conventional and the low angle steel belted tyre according to the present invention almost takes similar time for building a green tyre. Let a conventional tyre (also low angle steel belted tyre) take approximately about x minutes to build a green tyre (Time index taken as 100), a similar sized spirally wound tyre (with single steel cord winding method) takes about 300 index to build a single Green tyre.

Additional process controls are required in the case of steel wire winding such as pitch control (distance between adjacent cords of the belt) and tension control. The pitch also may be varying in some cases between the centre of the tyre and in the shoulder. But in the case of conventional method, the pitch is constant which is controlled when calendaring the Belt.

The Growth of a spirally wound steel tyre as shown in Figure 2 is ideally zero where Growth refers to the difference in diameter between the cured tyre taken out from the mould and the diameter of the same tyre mounted on a specified rim. The Growth in a conventional fabric belted tyre is high. The Growth in the case of the low angle steel belted tyre according to the present invention is minimal.

Thus, the pneumatic low angle steel belt tyre for two wheeled vehicle, has improvements in tyre life, high speed cornering performance, Better braking distance and Puncture reduction without changing the tread compound, Rubber volume and Non-skid depth. These benefits can be achieved without major change in the conventional manufacturing operation and manufacturing cycle time. Thus, the pneumatic low angle steel belt tyre for two wheeled vehicle according to the present invention is applicable for both Radial and Bias construction.

It will be apparent to a person skilled in the art that the above description is for illustrative purposes only and should not be considered as limiting. Various modifications, additions, alterations, and improvements without deviating from the scope of the invention may be made by a person skilled in the art.
, Claims:WE CLAIM:
1. A pneumatic low angle steel belted tyre for two wheeled vehicle, said pneumatic tyre comprising of:
a tyre casing having a tread portion (1) disposed on the outermost surface, said tread portion (1) contacts the ground during operation of the tyre;
a pair of low angle steel belts (2a, 2b) positioned below the tread portion (1) diagonally and also with opposite lay;
a rubber strip (2c) interspersed between the first steel belt (2b) and second steel belt (2a);
a body ply (3) positioned below the first steel belt (2b);
two spaced inextensible beads (4a, 4b);
a pair of chafers (5a, 5b);
a pair of apex (6a, 6b);
a pair of sidewalls (7a, 7b) extending radially inward from the axial outer edges of said tread portion (1) to join the two spaced inextensible beads (4a, 4b), the axial outer edges of the tread portion (1) defining a tread width; and
an inner liner (8) positioned extending radially inward surrounding the body ply (3).

2. The pneumatic low angle steel belted tyre as claimed in claim 1, wherein the ratio of Shoulder drop (c) to Tread Cord Width (a) divided by the Aspect ratio (AR) of the tyre is in the range 0.502 to 0.630.

3. The pneumatic low angle steel belted tyre as claimed in claim 1, wherein the ratio of Tread Arc Radius 1 (e) to the Tread Cord Width (a) of the tyre is in the range 0.374 to 0.542.

4. The pneumatic low angle steel belted tyre as claimed in claim 1, wherein the ratio of Tread Arc Width (b) to the Shoulder drop (c) multiplied by the Aspect ratio (AR) of the tyre is in the range 1.80 to 2.60.

5. The pneumatic low angle steel belted tyre as claimed in claim 1, wherein the ratio of Tread Arc Width (b) to the Tread Arc radius 1 (e) divided by the Aspect ratio (AR) of the tyre is in the range 2.00 to 2.57.

6. The pneumatic low angle steel belted tyre as claimed in claim 1, wherein the ratio of Shoulder Gauge (k) to Centre gauge (j) is in the range 0.85 to 1.1.

7. The pneumatic low angle steel belted tyre as claimed in claim 1, wherein the ratio of Apex height (i) to the Shoulder Drop (c) is in the range 0.1 to 0.4.

8. The pneumatic low angle steel belted tyre as claimed in claim 1, wherein the ratio of Ply turn up height (h) to the Shoulder drop (c) is in the range 0.1 to 0.6.

9. The pneumatic steel belted tyre as claimed in claim 1, wherein breaking strength of the steel belt (2a, 2b) is in range 40 to 80.

10. The pneumatic steel belted tyre as claimed in claim 1, wherein elongation at break of the steel belt (2a, 2b) is about 2 to 3 %.

11. The pneumatic low angle steel belted tyre as claimed in claim 1, wherein the steel belt (2a, 2b) Ends per Inch (EPI) is in range 16 to 30.

12. The pneumatic low angle steel belted tyre as claimed in claim 1, wherein the steel belt (2a, 2b) angle is in range 12 to 30 degree.

13. The pneumatic low angle steel belted tyre as claimed in claim 1, wherein number of filaments in the steel wires used in the steel belts (2a, 2b) is about 1 to 3.

Dated this 6th day of October 2022
-SD
Kalyan Jhabakh (IN/PA-830)
Agent for Applicant