DESC:PNEUMATIC TYRE WITH CELLULAR LAYER
FIELD OF INVENTION
The present invention relates to the field of pneumatic tyre in automotive vehicles. More particularly, the present invention relates to a pneumatic tyre with cellular layer, which has improved ride comfort and handling, felt by a common rider. Advantageously, the present invention has improved steering control.
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, shoulder, and ply.
Apart from the characteristic properties like rolling resistance and tyre life, handling and ride comfort has become an important property for the passenger car tyres. Tyre has to give anti vibrational ride comfort against the compressive forces offered by the vehicle load. The outcome of this phenomenon by the tyre can be experienced as a cushion effect by the passenger. Achieving anti-vibrational ride comfort without deterioration in the regular characteristic performances of the tyre is an open challenge for the tyre manufacturers. The tyre has to also perform well in providing adequate handling performance while doing manoeuvring, both at low speed and high speed. The tyre, hence has to provide both precision in turning, with the input given via steering wheel and provide adequate confidence to the driver while performing the said manoeuvring.
Rubber compounds with closed cell structures can damp vibrational forces caused by the vehicle load. Millions of closed cellular structures filled with gases can support the vehicle load which in turn can be reflected as a cushion effect by the tyres. This effect is dependent on various factors like number of closed cells, thickness of the closed cellular rubber layer, and location of the closed cellular rubber layer in the tyre etc.
Some of the Prior arts are:
U. S. Patent No. 5,109,902 and US 2009/0071584 A1 disclose pneumatic tyres with the tread rubber constituted by a base rubber made of a cellular compound and a cap rubber made of a non-cellular compound to impart ride comfort to the tyres.
U. S. Patent Nos. 4,249,588; 5,147,477; 5,788,766 describe the use of cellular rubber compounds at the outer, ground contacting tread position of the tyre to achieve excellent snow, ice and wet tractions.
U. S. Patents Nos. US 7,389,802 B2; US 2017/0050474 A1 explain the application of cellular rubber as the innermost layer of the tyre to reduce the noise produced by the air vibrations of the air chamber. However, cellular rubber with open cell structures with bigger diameter was used for noise damping.
U. S. 0,071,584 A1 explains the tyre with tread configuration comprised of an intermediate cellular rubber compound as a transition layer positioned between outer tread cap non-cellular rubber layer and a circumferential tread base non-cellular rubber layer.
WO2011051203A1 discloses a tyre wherein the inner wall of the tyre is provided with a rubber layer which is heat expandable when the tyre is in the crude state and expanded when the tyre is in the vulcanized state. This layer, when disposed between the sealing layer and the cavity of the tyre, once expanded, makes it possible to substantially reduce the noise due to rolling perceived inside the vehicle.
JPH0640206A discloses a pneumatic tyre comprising of a foam rubber layer covering the inner liner from the inside of the said inner liner of the tyre. The foam ratio of the foam rubber is disclosed to be in a range of 10-95%. The primary mode of resonant vibration is thereby absorbed to lower the peak value, so that the peak noise of road noise can be positively reduced.
Among the above cited prior arts, some inventions disclosed help in improving ride comfort, while some in reducing the in-cabin noise and traction. None of the prior arts disclose a pneumatic tyre with cellular layer which provides comprehensive improvement including improved ride comfort, handling, and steering control, felt by a common rider. Accordingly, there exists a need for a pneumatic tyre with cellular layer with improved performance having improved ride comfort as well as handling along with the better steering control felt by a common rider. Additionally, there exists a need for a pneumatic tyre with cellular rubber located at different positions with improved performance having improved ride comfort as well as handling along with the steering control felt by a common rider.
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 tyre with cellular layer located at different positions of the tyre with improved performance including improved ride comfort as well as handling along with the steering control felt by a common rider.
Yet another object of the present invention to provide a pneumatic tyre with cellular layer with improved steering control.
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 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 base positioned below the tread portion to support said tread portion; a ply; a cushion positioned between base and ply; a pair of belts; two spaced inextensible beads; a pair of rim cushions; a pair of chafers; a pair of apex; a pair of individual sidewalls extending radially inward from the axial outer edges of said tread portion to join the respective beads, the axial outer edges of the tread portion defining a tread width; a pair of wings on either side to support the tread portion and sidewalls; a body ply extending from the beads and across the tread; an inner liner positioned extending radially inward surrounding the body ply; and a cellular layer is positioned as additional layer at one or more locations in the said pneumatic tyre, wherein the thickness of the cellular layer is in the range 0.5 mm to 10 mm.
In an embodiment of the present invention, the cellular layer positioned between the body ply and inner liner (ZL-1, ZL-2), as an additional layer.
In another embodiment of the present invention, the cellular layer positioned at both ends of the bead area between the rim cushion and chafer ZL-5 as an additional layer.
In another embodiment of the present invention, the cellular layer positioned between the ply and inner liner from bead to bead (ZL-6), as an additional layer.
In yet another embodiment of the present invention, the cellular layer positioned between two rim cushion layers (ZL-7), as an additional layer.
According to various embodiments of the present invention, the cellular layer is cellular rubber layer having closed cell structure.
In the preferred embodiment of the present invention, the cellular layer has higher number of closed cells with lower diameter in its structure.

In the preferred embodiment of the present invention, the diameter of the closed cell is in the range of 50-100 µm.
In another embodiment of the present invention, the thickness of the cellular layer is 1 mm to 10 mm, preferably 3 mm.
Another embodiment of the present invention, the cellular layer, comprising: polymer matrix for cellular compounds; and chemical blowing agent.
In the preferred embodiment of the present invention, the chemical blowing agent concentration in the range of 1 to 10 phr is used to foam the polymer matrix for cellular compounds in the cellular layer.
In the preferred embodiment of the present invention, the chemical blowing agent includes activated Azodicarbonamide and p,p'-oxybis(benzenesulfonyl hydrazide).
BRIEF DESCRIPTION OF DRAWINGS
Figure 1a: illustrates various components in a pneumatic passenger car tyre
Figure 1: Illustrates the transverse sectional view of the pneumatic tyre with cellular layer located between body ply and inner liner according to one embodiment of the present invention.
Figure 2: Illustrates the microscopic image of the cellular rubber layer having closed cell structure according to one embodiment of the present invention.
Figure 3: Illustrates the graph plotted for varying diameter of the cellular rubber layer having closed cell structure as shown in Figure 2 according to one embodiment of the present invention.
Figure 4: Illustrates the graph showing subjective transmissibility and impact test, which can be correlated to the damping and impact force of the pneumatic tyre with cellular layer of 2mm (ZL1) and pneumatic tyre with cellular layer of 3mm (ZL2) in comparison to control version of a pneumatic tyre without cellular layer in normal usage.
Figure 5: Illustrates the graph showing subjective cornering power measurements of the pneumatic tyre with cellular layer of 2mm (ZL1) and pneumatic tyre with cellular layer of 3mm (ZL2) in comparison to control version of a pneumatic tyre without cellular layer in normal usage.
Figure 6: Illustrates the transverse sectional view of the pneumatic tyre with cellular layer positioned at both ends of the bead area between the rim cushion and chafer (ZL-5), as an additional layer according to second embodiment of the present invention.
Figure 7: Illustrates the transverse sectional view of the pneumatic tyre with cellular layer positioned between the ply and inner liner from bead to bead (ZL-6) as an additional layer according to third embodiment of the present invention.
Figure 8: Illustrates the transverse sectional view of the pneumatic tyre with cellular layer positioned between two rim cushion layers (ZL-7), as an additional layer according to fourth embodiment of the present invention.
DETAILED DESCRIPTION OF THE INVENTION WITH REFERENCE TO THE DRAWINGS
The present invention as embodied by a "Pneumatic tyre with cellular layer" 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 discloses a pneumatic tyre with improved performance characteristics which has been identified through the application of cellular rubber at different locations of the tyre, the said locations not being reported in the prior art, and the consequent effects on tyre characteristic performances.
Referring to Figure 1a , in an embodiment of the present invention, the 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 base (2) positioned below the tread portion (1) to support said tread portion (1), a ply (3), a cushion (4) positioned between base (2) and ply (3), a pair of belts (5a, 5b), two spaced inextensible beads (6), a pair of rim cushions (7), a pair of chafers (8), a pair of apex (9), a pair of individual sidewalls (10) extending radially inward from the axial outer edges of said tread portion (1) to join the respective beads (6), the axial outer edges of the tread portion (1) defining a tread width, a pair of wings (11) on either side to support the tread portion (1) and sidewalls (10), a body ply (11) extending from the beads (6) and across the tread portion (1), an inner liner (12) positioned extending radially inward surrounding the body ply (11); and wherein a cellular layer (13) positioned as additional layer at one or more locations in the said pneumatic tyre.
In the preferred embodiment of the present invention, thickness of the cellular layer (13) is in the range 0.5 mm to 10 mm. Particular embodiments have the thickness of the cellular layer (13) in the range of 1 mm to 10 mm, preferably 3 mm.
In the preferred embodiment of the present invention, the cellular layer (13) is cellular rubber layer having closed cell structure. As shown in Figure 2, the cellular layer (13) has higher number of closed cells with lower diameter in its structure.
In the preferred embodiment of the present invention, the higher number of lower diameter closed cell structure helps in providing a cushioning effect for the pneumatic tyre. Further, in reference to Figure 2, the diameter of the closed cell is in the range of 50-100 µm.
In another embodiment of the present invention, cellular layer, comprises polymer matrix for cellular compounds, and chemical blowing agent. In the preferred embodiment of the present invention, the chemical blowing agent is in a concentration range of 1 to 10 phr used to foam the polymer matrix for cellular compounds in the cellular layer.
In an exemplary embodiment of the present invention, the chemical blowing agent particularly of concentration 3 Phr.
In the preferred embodiment of the present invention, the chemical blowing agent includes activated Azodicarbonamide and p,p'-oxybis(benzenesulfonyl hydrazide).
Polymer matrix and Choice: In one embodiment of the present invention, bromobutyl rubber (BIIR) is used as polymer matrix for cellular compounds in the cellular layer. In another embodiment, chlorobutyl rubber (CIIR) is used as the polymer matrix for cellular compounds in the cellular layer. In another embodiment, natural rubber (NR) is used as polymer matrix for cellular compounds in the cellular layer, in another embodiment styrene-butadiene rubber (SBR) is used as polymer matrix for cellular compounds in the cellular layer. The invention in another embodiment used polybutadiene rubber (BR) as polymer matrix for cellular compounds in the cellular layer. Different polymer matrix can be selected for this application based on its compatibility with the neighbouring components in the tyre.Another embodiment of the present invention provides a method for preparing the cellular layer (13) comprising steps of: Mixing for the cellular rubber compound which is conducted in two stages. In the first stage, polymers, filler and chemicals except curatives and blowing agents were added and mixed to higher temperature (140 – 160 °C). In the second stage, the curatives along with the blowing agents were added to the mixture and mixed well below the decomposition temperature of the blowing agents (100 – 110 °C). The mixed compound is then calendared to the desired length x breadth x thickness and positioned as additional layer at one or more locations in the said pneumatic tyre.during the tire building process.
In the preferred embodiment of the present invention, the cellular layer (13) is incorporated into the pneumatic tire by assembling the cellular layer (13) during the tire building process at the predesigned locations. In preferred embodiment of the present invention, the Pre designated locations comprises of between body ply and inner liner (ZL-1, ZL-2), between both ends of the bead area between rim cushion and chafer (ZL-5). Between ply and inner liner from bead to bead (ZL-6), between two rim cushion layers (ZL-7). All representative figures depict the control as without cellular layer, and represented by ZL-8.
The green tyre assembly is cured in a curing press using a curing bladder, which forces expansion of the tire. During curing, the inner liner (12) expands with the carcass, which is forced against the indentations in the curing mold to form the tread portion (1) of the tyre, and all components are co-cured. Formation of the cellular structures takes place simultaneously with vulcanization process during the curing process of tyre. During curing at the vulcanization temperature, the foaming agents are decomposed and releases gases like nitrogen and carbon dioxide, which will be entrapped in the cross-linked rubber matrix to form the cellular layer (13).
In an embodiment of the present invention, the cellular layer (13) is positioned between the body ply (11) and inner liner (13), as an additional layer as shown in Figure 1 (ZL-1, ZL-2)
Another embodiment of the present invention, a method for tyre building process of the pneumatic tyre having cellular layer (13) is positioned between the body ply (11) and inner liner (12), as an additional layer as shown in Figure 1 comprising steps of: assembling the inner liner (13), body ply (11) and sidewall-rim cushion extrusion, on an expandable drum, on which a bead ring is inserted before expanding the drum and turning up the assembly to lock the beads in position. Simultaneously, tyre belt package is built on another drum that consists of the belt assembly, cap-ply, and cap-base-wing assembly. Finally, the two set of separate constructs, i.e. the carcass assembly and belt package are assembled together
In the preferred embodiment of the present invention, the cellular layer (13) is manually applied over the inner liner (13).
In the preferred embodiment of the present invention, the cellular layer (13) is taken as a preassembled layer along with inner liner (13).
Referring to Figure 6 (ZL-5), In second embodiment of the present invention, a 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 base (2) positioned below the tread portion (1) to support said tread portion (1), a ply (3), a cushion (4) positioned between base (2) and ply (3), a pair of belts (5a, 5b), two spaced inextensible beads (6), a pair of rim cushions (7), a pair of chafers (8), a pair of apex (9), a pair of individual sidewalls (10) extending radially inward from the axial outer edges of said tread portion (1) to join the respective beads (6), the axial outer edges of the tread portion (1) defining a tread width, a pair of wings (11) on either side to support the tread portion (1) and sidewalls (10), a body ply (11) extending from the beads (6) and across the tread portion (1), an inner liner (12) positioned extending radially inward surrounding the body ply (11); and a cellular layer (13) positioned at both ends of the bead (6) area between the rim cushion (7) and chafer (8) (ZL-5), as an additional layer. The thickness of the cellular layer (13) is in the range 0.5 mm to 10 mm. The thickness of the cellular layer (13) is 1 mm to 10 mm, preferably 3 mm, and the cellular rubber layer having closed cell structure.
In the preferred embodiment of the present invention, the cellular layer (13) has higher number of closed cells with lower diameter in its structure as shown in Figure 3.
In the preferred embodiment of the present invention, the higher number of closed cells with lower diameter in the cellular rubber layer structure helps in providing a cushioning effect for the pneumatic tyre.
In the preferred embodiment of the present invention, the diameter of the closed cell is in the range of 50-100 µm.
In another embodiment of the present invention, cellular layer, comprising: polymer matrix for cellular compounds; and chemical blowing agent.
In the preferred embodiment of the present invention, the chemical blowing agent in the range of 1 to 10 phr is used to foam the polymer matrix for cellular compounds in the cellular layer.
In the preferred embodiment of the present invention, the chemical blowing agent used is 3 Phr.
In the preferred embodiment of the present invention, the chemical blowing agent includes activated Azodicarbonamide and p,p'-oxybis(benzenesulfonyl hydrazide).
In the preferred embodiment of the present invention, bromobutyl rubber (BIIR) is used as polymer matrix for cellular compounds in the cellular layer. The polymer matrix is also made up of chlorobutyl rubber (CIIR), natural rubber (NR) styrene-butadiene rubber (SBR), polybutadiene rubber (BR) is used as polymer matrix for cellular compounds in the cellular layer.

Referring to Figure 7 (ZL-6), In third embodiment of the present invention, a 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 base (2) positioned below the tread portion (1) to support said tread portion (1), a ply (3), a cushion (4) positioned between base (2) and ply (3), a pair of belts (5a, 5b), two spaced inextensible beads (6), a pair of rim cushions (7), a pair of chafers (8), a pair of apex (9), a pair of individual sidewalls (10) extending radially inward from the axial outer edges of said tread portion (1) to join the respective beads (6), the axial outer edges of the tread portion (1) defining a tread width, a pair of wings (11) on either side to support the tread portion (1) and sidewalls (10), a body ply (11) extending from the beads (6) and across the tread portion (1), an inner liner (12) positioned extending radially inward surrounding the body ply (11) and a cellular layer (13) positioned between the ply (3) and inner liner (12) from bead (6) to bead (6) as an additional layer.

In the preferred embodiment of the present invention, thickness of the cellular layer (13) is in the range 0.5 mm to 10 mm. The thickness of the cellular layer (13) is 1 mm to 10 mm, preferably 3 mm. The cellular layer (13) is cellular rubber layer having closed cell structure.

In the preferred embodiment of the present invention, the cellular layer (13) has higher number of closed cells with lower diameter in its structure as shown in Figure 2. Diameter of the cell can be in the range of 50-100 µm. These higher number of lower diameter closed cell structure helps in providing a cushioning effect for the said application.

In another embodiment of the present invention, cellular layer, comprising: polymer matrix for cellular compounds; and chemical blowing agent.

In the preferred embodiment of the present invention, the chemical blowing agent in the range of 1 to 10 phr is used to foam the polymer matrix for cellular compounds in the cellular layer.

In the preferred embodiment of the present invention, the chemical blowing agent used is 3 Phr.

In the preferred embodiment of the present invention, the chemical blowing agent includes activated Azodicarbonamide and p,p'-oxybis(benzenesulfonyl hydrazide).

In the preferred embodiment of the present invention, bromobutyl rubber (BIIR) is used as polymer matrix for cellular compounds in the cellular layer, also, other rubbers like chlorobutyl rubber (CIIR), natural rubber (NR), styrene-butadiene rubber (SBR), polybutadiene rubber (BR) is used as polymer matrix for cellular compounds in the cellular layer.

Referring to Figure 8 (ZL-7), the fourth embodiment of the present invention, the 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 base (2) positioned below the tread portion (1) to support said tread portion (1), a ply (3), a cushion (4) positioned between base (2) and ply (3), a pair of belts (5a, 5b), two spaced inextensible beads (6), a pair of rim cushions (7), a pair of chafers (8), a pair of apex (9), a pair of individual sidewalls (10) extending radially inward from the axial outer edges of said tread portion (1) to join the respective beads (6), the axial outer edges of the tread portion (1) defining a tread width, a pair of wings (11) on either side to support the tread portion (1) and sidewalls (10), a body ply (11) extending from the beads (6) and across the tread portion (1), an inner liner (12) positioned extending radially inward surrounding the body ply (11); and a cellular layer (13) positioned between two rim cushion layers (7).
In the preferred embodiment of the present invention, thickness of the cellular layer (13) is in the range 0.5 mm to 10 mm.
In the preferred embodiment of the present invention, the thickness of the cellular layer (13) is 1 mm to 10 mm, preferably 3 mm.
In the preferred embodiment of the present invention, the cellular layer (13) is cellular rubber layer having closed cell structure.
In the preferred embodiment of the present invention, the cellular layer (13) has higher number of closed cells with lower diameter in its structure as shown in Figure 3.
In the preferred embodiment of the present invention, the higher number of closed cells with lower diameter in the cellular rubber layer structure helps in providing a cushioning effect for the pneumatic tyre.
In the preferred embodiment of the present invention, the diameter of the closed cell is in the range of 50-100 µm as illustrated in figure 2.
In another embodiment of the present invention, cellular layer, comprising: polymer matrix for cellular compounds; and chemical blowing agent.
In the preferred embodiment of the present invention, the chemical blowing agent in the range of 1 to 10 phr is used to foam the polymer matrix for cellular compounds in the cellular layer.
In the preferred embodiment of the present invention, the chemical blowing agent used is 3 Phr.
In the preferred embodiment of the present invention, the chemical blowing agent includes activated Azodicarbonamide and p,p'-oxybis(benzenesulfonyl hydrazide).

In the preferred embodiment of the present invention, bromobutyl rubber (BIIR) is used as polymer matrix for cellular compounds in the cellular layer, also, other rubbers like chlorobutyl rubber (CIIR), natural rubber (NR), styrene-butadiene rubber (SBR), polybutadiene rubber (BR) is used as polymer matrix for cellular compounds in the cellular layer.

In fifth embodiment of the present invention, a pneumatic tyre, comprises 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 base positioned below the tread portion to support said tread portion; a ply; a cushion positioned between base and ply; a pair of belts; two spaced inextensible beads; a pair of rim cushions; a pair of chafers; a pair of apex; a pair of individual sidewalls extending radially inward from the axial outer edges of said tread portion to join the respective beads, the axial outer edges of the tread portion defining a tread width; a pair of wings on either side to support the tread portion and sidewalls; a body ply extending from the beads and across the tread; an inner liner positioned extending radially inward surrounding the body ply; and a cellular layer positioned between body ply and belt-1 from bead to bead as an additional layer.

In the preferred embodiment of the present invention, thickness of the cellular layer (13) is in the range 0.5 mm to 10 mm.

In the preferred embodiment of the present invention, the thickness of the cellular layer (13) is 1 mm to 5 mm, preferably 3 mm.

In the preferred embodiment of the present invention, the cellular layer (13) is cellular rubber layer having closed cell structure.
In the preferred embodiment of the present invention, the cellular layer (13) has higher number of closed cells with lower diameter in its structure as shown in Figure 2. Diameter of the cell can be in the range of 50-100 µm. These higher number of lower diameter closed cell structure helps in providing a cushioning effect for the said application.

In another embodiment of the present invention, cellular layer, comprising: polymer matrix for cellular compounds; and chemical blowing agent.

In the preferred embodiment of the present invention, the chemical blowing agent in the range of 1 to 10 phr is used to foam the polymer matrix for cellular compounds in the cellular layer.

In the preferred embodiment of the present invention, the chemical blowing agent used is 3 Phr.

In the preferred embodiment of the present invention, the chemical blowing agent includes activated Azodicarbonamide and p,p'-oxybis(benzenesulfonyl hydrazide).

In the preferred embodiment of the present invention, bromobutyl rubber (BIIR) is used as polymer matrix for cellular compounds in the cellular layer, also, other rubbers like chlorobutyl rubber (CIIR), natural rubber (NR), styrene-butadiene rubber (SBR), polybutadiene rubber (BR) is used as polymer matrix for cellular compounds in the cellular layer.

In the preferred embodiment of the present invention, the pneumatic tyre is a passenger car tyre.

For illustration,
1. In one embodiment, Pneumatic tyre having cellular layer (13) with thickness 2 mm (ZL-1) and 3 mm (ZL-2) were positioned between body ply (11) and inner liner (12), as a additional layer as shown in Figure 1 for comparison against a control version without cellular rubber layer (ZL-8).

Example 1
The pneumatic tyre having cellular layer (13) with thickness 2 mm and 3 mm were positioned between body ply (11) and inner liner (12), as a additional layer for comparison against a control version without cellular rubber layer were subjected to objective tests for measuring the ride parameters including damping and impact force. These objective tests include transmissibility and impact test, which can be correlated to the damping and impact force respectively. In the transmissibility test, the tyres are hung to create a free-free boundary condition and the tyres are then excited by a slight hit using a modal hammer on tread portion of the tyre. The results obtained are plotted as impulse against frequency and for the curves obtained the smaller peak gives a better damping as shown in Figure 4

As for the impact test, the pneumatic tyres are run over a cleat at 40 KMPH speed and the radial force is measured and is done the following steps for processing,
1. Radial force is windowed by 0.05 s around peak (ie, +0.025/-0.025 s around the peak)
2. The integration of this windowed data provides Impulse (Ns) response of the pneumatic tyre. This results in a singular value, representing the impact force, for which smaller the value, the better. For the pneumatic tyre without cellular rubber the value was 30.44, while for ZL1 (Pneumatic tyre with 2 mm cellular rubber layer between body ply and inner liner) it was 29.64.

Example 2

The pneumatic tyre having cellular layer (13) with thickness 2 mm and 3 mm were positioned between body ply (11) and inner liner (12), as a additional layer for comparison against a control version without cellular rubber layer were subjected to load tests to measure handling performance of the pneumatic tyre. The Handling performances of the pneumatic tyres can be directly correlated to the cornering power measurements on a flat track machine with 1 degree slip angle. Generally, the cornering power values corresponding to 70% of the pneumatic tyre load index are used for comparison. Here, the graph illustrated in Figure 5 shows nearly 6% improvement in the cornering power for the ZL1 (Pneumatic tyre with 2 mm cellular rubber layer between body ply and inner liner) compared with control version of pneumatic tyre without cellular rubber and nearly 19% improvement for the ZL2 (Pneumatic tyre with 3 mm cellular rubber layer between body ply and inner liner) compared with control version of pneumatic tyre without cellular rubber. This data clearly shows the improvement in cornering power using cellular rubber layer which in turn can be correlated to the handling performance characteristics of the pneumatic tyre.

Example 3
The pneumatic tyre with cellular rubber layer (13) of thickness 2 mm positioned positioned between the body ply (11) and inner liner (12), as an additional layer as per the illustration in the figure 1 in comparison with pneumatic tyre without cellular rubber layer was subjected to ride and handling tests in a vehicle under controlled road and ride conditions under Vehicle inflation pressure .

Table 1 illustrates Ride and handling test results for control version of pneumatic tyre without cellular rubber and ZL1 (Pneumatic tyre with 2 mm cellular rubber layer between body ply and inner liner).
Table- 1
SI. No. Description Control ZL1
1 Ride Damping 6.5 7
2 Impact Force 6.5 7
3 Harshness 6.5 7
4 Handling Controllability at limits 6.5 7
5 Grip level 6.5 7
6 Yaw damping stability 6.5 7
7 Rear axle stability 6.5 7
8 Lane changing behaviour 6.5 7
9 Steering response 6.5 6.75
10 On centre 6.5 6.75

Example 4
The pneumatic tyre with cellular rubber layer of thickness 2 mm cellular layer (13) positioned between the body ply (11) and inner liner (12), as an additional layer in comparison with pneumatic tyre with cellular rubber layer of 3 mm made as per the illustration in the figures 1 was subjected to ride and handling tests in a vehicle under controlled road and ride conditions under vehicle inflation pressure

Table 2 illustrates ride and handling test results for ZL1 (Pneumatic tyre with 2 mm cellular rubber layer between body ply and inner liner) and ZL2 (Pneumatic tyre with 3 mm cellular rubber layer between body ply and inner liner). Here ZL1 was taken as the control version and the rating was given compared to ZL1.

Table- 2
SI. No. Description ZL1 ZL2
1 Ride Damping 7 7.25
2 Impact Force 7 7.25
3 Harshness 7 7
4 Handling Controllability at limits 7 7.25
5 Grip level 7 7.25
6 Yaw damping stability 7 7.25
7 Rear axle stability 7 7.25
8 Lane changing behaviour 7 7.25
9 Steering response 7 7
10 On centre 7 7.15

2. In another embodiment, Pneumatic tyre having cellular layer (13) with thickness 2 mm is positioned at both ends of the bead area (6) between the rim cushion (7) and chafer (8), as an additional layer for comparison against a control version without cellular rubber layer.

Example 5
The pneumatic tyre with cellular rubber layer (13) of thickness 2 mm positioned at both ends of the bead area (6) between the rim cushion (7) and chafer (8), as an additional layer (ZL5) as per the illustration in the figure 6 in comparison with pneumatic tyre without cellular rubber layer was subjected to ride and handling tests in a vehicle under controlled road and ride conditions under vehicle inflation pressure.

Table 3 illustrates Ride and handling test results for control of pneumatic tyre without cellular rubber and ZL5 (Pneumatic tyre with 2 mm cellular rubber layer (13) positioned at both ends of the bead area (6) between the rim cushion (7) and chafer (8).

Table- 3
SI. No. Description Control ZL5
1 Ride Damping 6.5 6.75
2 Impact Force 6.5 6.75
3 Harshness 6.5 7
4 Handling Controllability at limits 6.5 6.75
5 Grip level 6.5 6.75
6 Yaw damping stability 6.5 6.75
7 Rear axle stability 6.5 6.75
8 Lane changing behaviour 6.5 6.75
9 Steering response 6.5 6.75
10 On centre 6.5 6.75

3. In another embodiment, Pneumatic tyre having cellular layer (13) with thickness 2 mm is positioned between the ply (3) and inner liner (12) from bead (6) to bead (6), as an additional layer as per the illustration in the figure 7 for comparison against a control version without cellular rubber layer.

Example 6
The pneumatic tyre with cellular rubber layer (13) of thickness 2 mm positioned between the ply (3) and inner liner (12) from bead (6) to bead (6) (ZL-6), as an additional layer as per the illustration in the figure 7 in comparison with pneumatic tyre without cellular rubber layer was subjected to ride and handling tests in a vehicle under controlled road and ride conditions under Vehicle inflation pressure

Table 4 illustrates Ride and handling test results for control of pneumatic tyre without cellular rubber and ZL6 (Pneumatic tyre with 2 mm cellular rubber layer positioned between the ply and inner liner from bead to bead).
Table- 4
SI. No. Description Control ZL6
1 Ride Damping 6.5 7
2 Impact Force 6.5 7
3 Harshness 6.5 7
4 Handling Controllability at limits 6.5 6.75
5 Grip level 6.5 6.75
6 Yaw damping stability 6.5 6.75
7 Rear axle stability 6.5 6.75
8 Lane changing behaviour 6.5 6.75
9 Steering response 6.5 7
10 On centre 6.5 7

4. In another embodiment, Pneumatic tyre having cellular layer (13) with thickness 2 mm is positioned between two rim cushion layers (7) (ZL-7), as an additional layer as per the illustration in the figure 8 for comparison against a control version without cellular rubber layer.

Example 7
The pneumatic tyre with cellular rubber layer (13) of thickness 2 mm positioned between two rim cushion layers (7) (ZL-7), as an additional layer as per the illustration in the figure 8 in comparison with pneumatic tyre without cellular rubber layer was subjected to ride and handling tests in a vehicle under controlled road and ride conditions under Vehicle inflation pressure
Table 5 illustrates Ride and handling test results for control of pneumatic tyre without cellular rubber and ZL7 (Pneumatic tyre with 2 mm cellular rubber layer positioned between two rim cushion layers).

Table- 5
SI. No. Description Control ZL7
1 Ride Damping 6.5 6.75
2 Impact Force 6.5 6.75
3 Harshness 6.5 7
4 Handling Controllability at limits 6.5 7
5 Grip level 6.5 7
6 Yaw damping stability 6.5 7
7 Rear axle stability 6.5 7
8 Lane changing behaviour 6.5 7
9 Steering response 6.5 7
10 On centre 6.5 6.75

Based on the above ride and handling test results carried out with the pneumatic tyre with cellular layer located at different positions of the tyre, pneumatic tyre having the cellular layer of thickness of 3mm positioned between the body ply and inner liner (ZL-2), as an additional layer found to have improved performance including improved ride comfort as well as handling along with the steering control felt by a common rider.
,CLAIMS:WE CLAIM:

1. A 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 base (2) positioned below the tread portion (1) to support said tread portion (1); a ply (3); a cushion (4) positioned between base (2) and ply (3); a pair of belts (5a, 5b); two spaced inextensible beads (6); a pair of rim cushions (7); a pair of chafers (8); a pair of apex (9); a pair of individual sidewalls (10) extending radially inward from the axial outer edges of said tread portion (1) to join the respective beads (6), the axial outer edges of the tread portion (1) defining a tread width; a pair of wings (11) on either side to support the tread portion (1) and sidewalls (10); a body ply (11) extending from the beads (6) and across the tread portion (1); an inner liner (12) positioned extending radially inward surrounding the body ply (11); and Characterized in that a cellular layer (13) is positioned as an additional layer at one or more locations in the said pneumatic tyre,
wherein the thickness of the cellular layer (13) is in the range 0.5 mm to 10 mm.

2. The pneumatic tyre as claimed in claim 1, the cellular layer (13) is positioned between the body ply (11) and inner liner (13), as an additional layer.

3. The pneumatic tyre as claimed in claim 1, the cellular layer (13) is positioned at both ends of the bead (6) area between the rim cushion (7) and chafer (8) as an additional layer.

4. The pneumatic tyre as claimed in claim 1, the cellular layer (13) is positioned between the ply (3) and inner liner (12) from bead (6) to bead (6), as an additional layer.

5. The pneumatic tyre as claimed in claim 1, the cellular layer (13) is positioned between two rim cushion (7) layers, as an additional layer.
6. The pneumatic tyre as claimed in claim 1, wherein the cellular layer (13) is a cellular rubber layer having closed cell structure.

7. The pneumatic tyre as claimed in claim 6, wherein the cellular layer (13) has higher number of closed cells with lower diameter in its structure.

8. The pneumatic tyre as claimed in claim 7, wherein the diameter of the closed cell is in the range of 50-100 µm.

9. The pneumatic tyre as claimed in claim 1, wherein the thickness of the cellular layer (13) is 1 mm to 10 mm, preferably 3 mm.

10. A cellular layer, comprising:
a) polymer matrix for cellular compounds; and
b) chemical blowing agent,
wherein the chemical blowing agent concentration in the range of 1 to 10 phr is used to foam the polymer matrix for cellular compounds in the cellular layer.

11. The cellular layer as claimed in claim 8, wherein bromobutyl rubber is used as polymer matrix for cellular compounds in the cellular layer.

12. The cellular layer as claimed in claim 8, wherein chlorobutyl rubber (CIIR) is used as polymer matrix for cellular compounds in the cellular layer.

13. The cellular layer as claimed in claim 8, wherein natural rubber (NR) is used as polymer matrix for cellular compounds in the cellular layer.

14. The cellular layer as claimed in claim 8, wherein styrene-butadiene rubber (SBR) is used as polymer matrix for cellular compounds in the cellular layer.

15. The cellular layer as claimed in claim 8, wherein polybutadiene rubber (PBD) is used as polymer matrix for cellular compounds in the cellular layer.

16. The cellular layer as claimed in claim 8, wherein the chemical blowing agent concentration is 3 Phr.

17. The cellular layer as claimed in claim 8, wherein the chemical blowing agent includes activated Azodicarbonamide and p,p'-oxybis(benzenesulfonyl hydrazide).

Dated this 29th day of September 2021