Claims:WE CLAIM:
1. A pneumatic run flat tyre for two wheeled vehicle, said pneumatic run flat 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 second ply (2a) positioned below the tread portion (1); a first ply (2b) positioned below the second ply (2a); two spaced inextensible beads (6a, 6b); a pair of chafers (4a, 4b); a pair of apex (3a, 3b); a pair of sidewalls (8a, 8b) extending radially inward from the axial outer edges of said tread portion (1) to join the respective beads (6a, 6b), the axial outer edges of the tread portion (1) defining a tread width; and an inner liner (5) positioned extending radially inward surrounding the first ply (2b), Characterized in that
a) A crown insert (4) is positioned between the inner liner (5) and first ply (2b), covering the tread region (1) and extending up to mid-sidewall point; and
b) A sidewall stiffener (7) is positioned between second ply (2a) and the apex (3a, 3b) in the lower sidewall region, said sidewall stiffener (7) extending from above the beads (6a, 6b) and ending at upper sidewall region, having an overlap with the crown insert (4),
wherein the apex (3a, 3b) is positioned extending up to mid-sidewall point in the radial direction, having an overlap with the crown insert (4), ending below the sidewall stiffener (7).

2. The pneumatic run flat tyre as claimed in claim 1, wherein the crown insert (4) is a profiled component whose width goes on decreasing from centre of the tyre to the ending in both sides.

3. The pneumatic run flat tyre as claimed in claim 1, wherein the sidewall stiffener (7) is positioned 5 to 10 mm above the beads (6a, 6b) and ending at upper sidewall region, having an overlap of 10 to 15 mm with the crown insert (4).

4. The pneumatic run flat tyre as claimed in claim 1, wherein the apex (3a, 3b) is positioned extending up to mid-sidewall point, having an overlap of 5 to 10mm with crown insert (4).

5. The pneumatic run flat tyre as claimed in claim 1, wherein the crown insert (4) is made up of a rubber compound.

6. The pneumatic run flat tyre as claimed in claim 1, wherein the sidewall stiffener (7) is made up of a very stiff fabric.

7. The pneumatic run flat tyre as claimed in claim 1, wherein the sidewall stiffener (7) is made up of a rubber coated fabric material with an optimum angle of 40 to 50 degrees.
, Description:PNEUMATIC RUN FLAT TYRE FOR TWO WHEELED VEHICLE
FIELD OF INVENTION
The present invention relates to the field of pneumatic tyres in automotive vehicles. More particularly, the present invention relates to a pneumatic run flat tyre for two wheeled vehicles, which runs on flat conditions preventing collapse of the tyre. Further, the present invention relates to a pneumatic run flat tyre for two wheeled vehicle, which maintains the fuel efficiency as a regular tyre during normal usage, without compromising much on the comfort.
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 ply, and ply.
Pneumatic tyres designed for sustained operation when "uninflated" ("flat") or under inflated are also called "runflat" tyres, as they are capable of being driven in the "flat" condition. They are also called extended mobility technology tyres, or "EMT" tyres. A conventional pneumatic tyre will collapse upon itself when it is uninflated and carrying the weight of a vehicle. The sidewalls of the tyre buckle outward in the circumferential portion of the tyre where the tread contacts the ground, making the tyre "flat". If the tyre is punctured while running, it will result in gradual loss of air from the tyre, making the pneumatic tyre not capable of supporting the load of the vehicle thereby not being able to maintain the required durability or required steering stability needed for the vehicle to run in a straight direction thereby resulting in making an unnecessary turn or running in a zigzag movement.
Some of the prior arts to avert this are discussed below:
U. S. Patent No. 6,938,659 B2 discloses a run flat motorcycle tire that incorporates a Crown insert, long Apex along with two Belts and the first belt extending beyond the tread region into the sidewall.
U. S. Patent No. 4,263,955 A discloses a pneumatic run flat tire for motorcycles, the said tire is provided with reinforced sidewall portions having such a high rigidity that even when the tire is punctured while running, the motorcycle will have a high handling stability during straight and zigzag runnings, cornering stability and durability. The pneumatic run flat tire incorporates crown rubber insert, bead filler, sidewall rubber filler, cord fabric breaker layer in its layout.
WO199856602A discloses designing of lower sidewall and bead area of a run-flat tire to reduce the effort in mounting the tire on a standard rim and to improve the retention of the tire on the standard rim during a loss of inflation pressure. The run flat tire incorporates Belt package, sidewall stiffening rubber inserts, bead filler in its layout.
US 2020/0324583 A1 discloses a run-flat tire that includes a tread portion, reinforcing rubber in a sidewall, first bead filler rubber disposed toward the inside of a folded back portion of a carcass layer in a lateral direction, and second bead filler rubber disposed toward the outside of the folded back portion in the lateral direction. The tread portion includes a belt layer toward the outside of the carcass layer in the tire radial direction.
U. S. Patent No. 5,217,549 A discloses a pneumatic safety tire, which has a wall stiffness such that when the tire is punctured during running, the tire can bear the load of the vehicle to allow for continued relatively high speeds for a relatively long distance under normal highway driving conditions until the proper repair or tire replacement can be made. The pneumatic safety tire incorporates belt plies at crown, bead filler, sidewall rubber Insert in its layout.
WO2009103733A1 discloses a run- flat radial tyre comprising: a crown comprising a crown reinforcement surmounted by a tread; two sidewalls extending the crown radially inward; two beads radially inward to the sidewalls and each comprising an annular reinforcing structure; at least one carcass reinforcement anchored in each of the beads and extending from the beads through the sidewalls toward the crown; and at least one sidewall insert axially on the inside of the carcass reinforcement, intended to reinforce the sidewall, comprising at least one polymer compound, each sidewall insert being capable of withstanding a load corresponding to part of the weight of the vehicle in a situation in which the inflation pressure is substantially reduced or zero.
US Patent No. 6,119,748 A discloses a pneumatic tire for run-flat running comprising a stiffener rubber, viewing a cross-section of the tire-rim assembly inflated under an air pressure corresponding to 15% of a maximum air pressure of the tire, a top of the stiffener rubber is located inward from a specified line segment PA in a radial direction of the tire, and on an outer periphery of a carcass is arranged a belt reinforcing the tread portion. The pneumatic tire incorporates belt plies at crown, bead filler, sidewall rubber Insert in its layout.
Korean Patent No.1010917110000 discloses a pneumatic tire for preventing punctures from deteriorating steering stability and ride comfort by a reinforcing rubber installed inside a sidewall of a tire.
None of the prior arts disclose a pneumatic run flat tyre for two wheeled vehicle, which maintains the fuel efficiency as a regular tyre during normal usage without compromising much on the comfort. Further, conventional run flat tyres as disclosed in the prior arts cause discomfort in the ride due to the presence of the breaker or belt in the crown region. Accordingly, there exists a need for a pneumatic run flat tyre for two wheeled vehicle, which enables said tyre to run on flat conditions preventing tyre collapse and travel can be continued without repairing until getting an opportunity to restore the tyre back to normal working. Additionally, there exists a need for a pneumatic run flat tyre for two wheeled vehicles, which maintains the fuel efficiency as a regular tyre during normal usage and without compromising much on the comfort.
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 person skilled in the art.
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 run flat tyre for two wheeled vehicle, which enables said tyre to run on flat conditions preventing collapse of the tyre and its usage can be continued without repairing until getting an opportunity to restore the tyre back to normal working.
Yet another object of the present invention is to provide a pneumatic run flat tyre for two wheeled vehicle, which maintains the fuel efficiency as a regular tyre during normal usage without compromising much on the comfort.
Yet another object of the present invention is to provide a pneumatic run flat tyre at rated inflation pressure for two wheeled vehicle, which maintains the 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, as maintained by a regular tyre in normal usage.
Yet another object of the present invention is to provide a pneumatic run flat tyre for two wheeled vehicle, which maintains the shape of said tyre in crown portion both in normal and flat condition without using breaker or belt.
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
In an embodiment of the present invention, the subject matter relates to a pneumatic run flat tyre for two wheeled vehicle, said pneumatic run flat 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 second ply (2a) positioned below the tread portion (1); a first ply (2b) positioned below the second ply (2a); two spaced inextensible beads (6a, 6b); a pair of chafers (4a, 4b); a pair of apex (3a, 3b); a pair of sidewalls (8a, 8b) extending radially inward from the axial outer edges of said tread portion (1) to join the respective beads (6a, 6b), the axial outer edges of the tread portion (1) defining a tread width; and an inner liner (5) positioned extending radially inward surrounding the first ply (2b), Characterized in that a crown insert (4) is positioned between the inner liner (5) and first ply (2b), covering the tread region (1) and extending up to mid-sidewall point; and a sidewall stiffener (7) is positioned between second ply (2a) and the apex (3a, 3b) in the lower sidewall region, said sidewall stiffener (7) extending from above the beads (6a, 6b) and ending at upper sidewall region, having an overlap with the crown insert (4), wherein the apex (3a, 3b) is positioned extending up to mid-sidewall point in the radial direction, having an overlap with the crown insert (4), ending below the sidewall stiffener (7).
In the preferred embodiment of the present invention, the pneumatic run flat tyre performs consistently in both normal and flat conditions, which can be ridden to a safer distance under puncture and also maintains the ride comfort and fuel efficiency as regular tyres during normal condition.
In the preferred embodiment of the present invention, the pneumatic run flat tyre maintains the shape of said tyre in the crown portion both in normal and flat condition without using breaker or belt.
In the preferred embodiment of the present invention, the pneumatic run flat tyre maintains the 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, as maintained by a regular tyre in normal usage.

BRIEF DESCRIPTION OF DRAWINGS
Figure 1: Illustrates the transverse sectional view of the pneumatic run flat tyre for two wheeled vehicle according to the present invention.
Figure 2: Illustrates the transverse sectional view of the pneumatic run flat tyre for two wheeled vehicle showing components in different colour according to the present invention.
Figure 3: Illustrates the graph showing 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 of the pneumatic run flat tyre for two wheeled vehicle in comparison to a regular tyre in normal usage.

DETAILED DESCRIPTION OF THE INVENTION WITH REFERENCE TO THE DRAWINGS

The present invention as embodied by a "Pneumatic run flat 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 a pneumatic run flat tyre for two wheeled vehicle, which enables said tyre to run on flat conditions preventing collapse of the tyre.

Referring to Figures 1 to 2, in an embodiment of the present invention, the pneumatic run flat tyre for two wheeled vehicle comprises 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 second ply (2a) positioned below the tread portion (1); a first ply (2b) positioned below the second ply (2a); two spaced inextensible beads (6a, 6b); a pair of chafers (4a, 4b); a pair of apex (3a, 3b); a pair of sidewalls (8a, 8b) extending radially inward from the axial outer edges of said tread portion (1) to join the respective beads (6a, 6b), the axial outer edges of the tread portion (1) defining a tread width; and an inner liner (5) positioned extending radially inward surrounding the first ply (2b), Characterized in that a crown insert (4) is positioned between the inner liner (5) and first ply (2b), covering the tread region (1) and extending up to mid-sidewall point; and a sidewall stiffener (7) is positioned between second ply (2a) and the apex (3a, 3b) in the lower sidewall region, said sidewall stiffener (7) extending from above the beads (6a, 6b) and ending at upper sidewall region, having an overlap with the crown insert (4), wherein the apex (3a, 3b) is positioned extending up to mid-sidewall point in the radial direction, having an overlap with the crown insert (4), ending below the sidewall stiffener (7).

In the preferred embodiment of the present invention, the crown insert (4) is a profiled component whose width goes on decreasing from centre of the tyre to the ending in both sides.

In the preferred embodiment of the present invention, the sidewall stiffener (7) is positioned 5 to 10 mm above the beads (6a, 6b) and ending at upper sidewall region, having an overlap of 10 to 15 mm with the crown insert (4).

In the preferred embodiment of the present invention, the apex (3a, 3b) is positioned extending up to mid-sidewall point, having an overlap of 5 to 10mm with crown insert (4).

In the preferred embodiment of the present invention, the crown insert (4) is made up of a rubber compound.

In the preferred embodiment of the present invention, the crown insert (4) has hardness of 70-80 duros and a tensile strength of 13-16 MPa.

In the preferred embodiment of the present invention, the sidewall stiffener (7) is made up of a very stiff fabric such as a rubber coated fabric material with an optimum angle of 40 to 50 degrees.

In the preferred embodiment of the present invention, the pneumatic run flat tyre for two wheeled vehicle enables said tyre to run on flat conditions preventing collapse of tyre and its usage can be continued without repairing until getting an opportunity to restore the tyre back to normal working.

In the preferred embodiment of the present invention, the pneumatic run flat tyre for two wheeled vehicles maintains the shape of the said tyre in crown portion both in normal and flat conditions without using breaker or belt.

In the preferred embodiment of the present invention, the pneumatic run flat tyre for two wheeled vehicles maintains the fuel efficiency as a regular tyre during normal usage without much compromising on the comfort.

In the preferred embodiment of the present invention, the pneumatic run flat tyre for two wheeled vehicles maintains the 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, as maintained by a regular tyre in normal usage.

For illustration,
Example 1
The pneumatic run flat tyre made as per the illustration in the figures 1 and 2 was subjected to load/speed performance as per IS standard 15627 under normal inflation. One hour is the minimum required time as per the standard IS-15627 and the pneumatic run flat tyre of the present invention has successfully passed the test by running more than one hour.

Example 2
The pneumatic run flat tyre as per the illustration in the figures 1 and 2 is tested for load/speed performance under zero inflation. The pneumatic run flat tyre was run on a testing wheel, under a load of 65% of load index. Twenty minutes is allowed to build up from zero to initial test speed of 60 Kmph. Afterwards, the tyre was run at this speed for the next 10 minutes. Then, speed was increased to maximum speed of 90 Kmph in speed steps of 10 Kmph. The tyre was run for 10 minutes at each speed step. Thus, total duration of the test for load/speed performance under zero inflation of the pneumatic run flat tyre is 1 hr. No damage was found to have occurred to the pneumatic run flat tyre after the test.

Example 3
The pneumatic run flat tyre as per the illustration in the figures 1 and 2 was tested for durability at track by running one hour continuously at 40 kmph under flat condition with a dead weight of 60 kg at the rear. The said test was performed 3 times with a tyre inspection gap of 30 minutes between each such test.

Footprint of the tyre was compared with that of a regular tyre at inflation pressures of 0 kPa(Flat condition) and 250 kPa(Normal condition) under a load of 80% of load index as shown in Table-1 below. At flat condition, this run flat tyre has 50% less flatness compared to regular tyre and this is visible in the footprint. Under normal condition, this pneumatic run flat tyre has almost same contact area and footprint as that of a regular tyre.

Table-1- Footprint comparison of pneumatic run flat tyre and regular tyre at a load of 206 Kg

Example 4
A dynamic bead unseat test was conducted on the pneumatic run flat tyre as per the illustration in the figures 1 and 2 as per BIS standard and the bead was not unseated.

The pneumatic run flat tyre as per the illustration in the figures 1 and 2 was made to run on a wheel drum of diameter 1.70 m at 30 kph and 88% Load Index to test dynamic bead unseating, wherein the camber and steer angle were kept at 10 degrees and 5 degrees respectively. In the starting of the test, the tyre was inflated to 70 kPa and then reduced to zero kPa in steps of 10 kPa by running for one minute in each inflation pressure. It was observed that the tyre passes the test if the bead is not unseated. In this test, the pneumatic run flat tyre of the present invention passed the test like the regular tyre.

Example 5
Fuel efficiency of the pneumatic run flat tyre as per the illustration in the figures 1 and 2 was compared with the regular tyre by conducting a rolling resistance test. The test was conducted as per the standard ISO 18164. Difference observed between the tyres, coefficient of rolling resistance of regular tyre is found to be 20.89 N/kN and the pneumatic run flat tyre according to present invention is found to be 20.64 N/kN. So, it can be concluded that the pneumatic run flat tyre according to the present invention is more or same as fuel efficient as that of the regular tyre.

Example 6
Ride and handling performance of the pneumatic run flat tyre as per the illustration in the figures 1 and 2 under flat condition (0 kPa) was compared against that of regular tyre under normal condition (250 kPa) by conducting a vehicle level testing. It was observed that the pneumatic run flat tyre according to the present invention is very stable in all the 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, brake feel as that of the regular tyre in normal usage, as illustrated in the graph shown in Figure 3.

Test condition:
Test vehicle: Honda Dio
Inflation pressure: Standard inflation pressure Vehicle standard (front: 22 Psi./rear: 29 psi)
Control: Both rear and front tyres are regular tyres with standard inflation pressure
Run flat: only change in the rear tyre (in rear fitment regular tyre replaced with pneumatic run flat tyre according to the present invention)

Thus, from the graph as shown in Figure 3, 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 more or less similar to that of a regular tyre in normal usage. The pneumatic run flat tyre according to the present invention has only marginal loss in ride comfort at rough road condition when compared to the regular tyre under normal condition (250 kPa) as shown in Figure 3, which may not be identifiable by a common user.

Example 7
The pneumatic run flat tyre as per the illustration in the figures 1 and 2 was punctured to check its reparability and reusability. The pneumatic run flat tyre according to the present invention was found to be reparable even with additional components at tread. Reusability of the repaired pneumatic run flat tyre according to the present invention was checked as per IS-15627 standard load speed test, and found repaired pneumatic run flat tyre according to the present invention runs for more than one hour thereby passing the test. .

Thus, the pneumatic run flat tyre for two wheeled vehicle according to the present invention enables said tyre to run on flat conditions preventing collapse and its usage can be continued without repairing until getting an opportunity to restore the tyre back to normal working. Also, the pneumatic run flat tyre of the present invention maintains the shape of the said tyre in crown portion both in normal as well as flat conditions without using a breaker or belt.

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.