FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION (See section 10, rule 13)
1. Title of the invention: TIRE NOISE CANCELLATION THROUGH INTERNAL CAVITY
DESIGN
2. Applicant(s)
NAME NATIONALITY ADDRESS
CEAT LIMITED Indian CEAT Ltd At: Getmuwala P.o.: Chandrapura Ta: Halol - 389350 Dist: Panchmahal, Gujarat, India
3. Preamble to the description
COMPLETE SPECIFICATION
The following specification particularly describes the invention and the manner in which it
is to be performed.

TECHNICAL FIELD
[0001] The present subject matter relates, in general, to tires and,
particularly, to tires having noise cancelling characteristics.
BACKGROUND
[0002] Pneumatic tires are commonly used in vehicles, such as
motorcycles, buses, trucks, cars, etc. Such tires are inflated with air and serve to provide a cushion between a vehicle and the ground thereby absorbing shock from surface irregularities.
[0003] Tires support load of a vehicle and impact handling, drivability, and
safety of the vehicle. A tire has a crown or center region, a shoulder region and beads on either side of the center region. In an example, the center region may be understood as outer region of the tire formed along complete circumference of the tire and spreads along width of the tire. Further, the center region contacts with surface during rotation. The beads may be understood as edges of the tire. The beads contact with wheel during mounting of the tire. The shoulder region is portion of the tire joining the center region and the beads of the tire. Vulcanized and treated rubber on the center region and shoulder region of the tire is a tread of the tire. The tread affects contact and interaction of the tire with road and thus affects traction of the vehicle and noise generated during the interaction of the tire with road surface.
[0004] There are many factors, other than interaction of tread with the road,
that are responsible for generation the tire noise, such as circumferential and vertical resonance of the air in the annular tire cavity. That is, a ring of air inside the tire continuous around the rim is excited by vibrations during running and resonates in the circumferential and vertical direction. Such type of noise is known as tire cavity noise. Tire cavity noise is one of the major factors contributing to the overall noise of a vehicle. It is desirable to reduce such

noise, without effecting other parameters of tire performance, such as vehicle maneuvering, safety, and ease of driving.
BRIEF DESCRIPTION OF DRAWINGS
[0005] The detailed description is described with reference to the
accompanying figures. In the figures, the left-most digit(s) of a reference
number identifies the figure in which the reference number first appears. The
same numbers are used throughout the drawings to reference like features
and components.
[0006] Figure 1 illustrates a plan view of a curing bladder for manufacturing
of pneumatic tires having noise cancelling characteristics, in accordance with
an implementation of the present subject matter.
[0007] Figure 2 illustrates a plan view of a curing bladder for manufacturing
of pneumatic tires having noise cancelling characteristics, in accordance with
another implementation of the present subject matter.
[0008] Figure 3 shows movement of sound waves passing through pores
of a pneumatic tire having parallel channel direction, in accordance with an
implementation of the present subject matter.
[0009] Figure 4 shows the movement of sound waves passing through
pores of a pneumatic tire having oblique channel direction, in accordance with
an implementation of the present subject matter.
[0010] Figure 5A-5B shows the cross-sectional view of a pneumatic tire
having noise cancelling characteristics, in accordance with an implementation
of the present subject matter.
DETAILED DESCRIPTION
[0011] The present subject matter relates to a pneumatic tire for a wheel
assembly having noise cancelling characteristics as well as to a corresponding curing bladder for manufacturing the pneumatic tire.

[0012] As the demands of consumers on the performance of automobiles
are becoming higher, the attention of the consumers on cavity noise of pneumatic tires has also increased. During driving of an automobile, if cavity noise of the tire is too high, it can be annoying for drivers and passengers. Tire cavity noise is one of the major factors contributing to the overall noise generated during operation of the automobile. In the absence of engine noise especially for electric vehicles, the cavity noise of pneumatic tires can be easily heard by the passengers in a completely silent cabin.
[0013] Circumferential and vertical resonance of the air in an annular tire
cavity is a major factor for cavity noise of the pneumatic tires. As mentioned above, a ring of air inside the pneumatic tire around the rim is excited by vibrations during running of the vehicle and resonates in the circumferential and vertical direction thereby leading to the vibration of air molecules present in the cavity. These vibrations generate sound waves which are perceived as noise, known as cavity noise, to an end user.
[0014] In some conventional techniques to reduce cavity noise, a sound-
absorbing material like foam is pasted on an inner liner surface of the pneumatic tire for cavity noise reduction of tires by increasing the air vibration damping in the cavity of the pneumatic tire. Since the adhesion capability and durability of the conventional sound-absorbing materials for the pneumatic tire with reduced cavity noise are not adequate, it is quite common that the sound-absorbing material is peeled as the stress is focused on a bonded interface due to the deformation caused by the vibration of the pneumatic tire. In some cases, the sound-absorbing material is damaged due to the external temperature. Under the conditions of high-speed rotation of a pneumatic tire, over high ambient temperature, over low ambient temperature, long service time of the pneumatic tire, and the like, the traditional method for adhering the sound-absorbing material easily causes the sound-absorbing material to fall

off or be damaged due to the viscosity change of the adhering rubber material of the pneumatic tire.
[0015] In view of the limitations inherent in the conventional methods and
in order to overcome the drawbacks of the conventional methods, the present
invention describes a pneumatic tire for a wheel assembly having noise
cancelling characteristics. The pneumatic tire comprises a tread portion and a
pair of sidewall portions provided on either side of the tread portion. The tread
portion comprises an inner liner surface having a plurality of protrusions
shaped as crest and trough with the plurality of protrusions being formed
throughout a circumference of the inner liner surface. Each of the plurality of
protrusions has a plurality of zig-zag pores along their respective surface.
Further, the pair of sidewall portions of the pneumatic tire comprises a plurality
of circular pores on an inner portion of either of the sidewall portions.
[0016] The protrusions along the circumference of the inner liner surface
act as barriers to the flow of air. The circumferential air running inside the pneumatic tire of a running vehicle passes through the plurality of protrusions shaped as crest and trough having the plurality of pores on the protrusions and undergoes absorption/reflections which significantly reduces the cavity noise of the pneumatic tire by significantly dissipating sound waves intensity of the air flow.
[0017] In accordance with an embodiment of the present subject matter, a
curing bladder for manufacturing of pneumatic tires having noise cancelling characteristics is also provided. The present invention describes a curing bladder for curing a pneumatic tire having noise cancelling characteristics. The curing bladder comprises an exterior wall having a drum-shape, wherein the exterior wall interfaces with an uncured pneumatic tire. The exterior wall is having a central region to interface with an inner liner surface located in an interior of a tread portion of the uncured pneumatic tire, and a pair of sidewall

regions on either side of the central region. The central region of the exterior
wall has a plurality of protrusions shaped as crest and trough; the plurality of
protrusions being formed throughout a circumference of the exterior wall. Each
of the plurality of crest and trough have a plurality of zig-zag protrusions along
their respective surface, and the pair of sidewall regions comprise a plurality
of circular protrusion on an outer surface of either of the sidewall regions.
[0018] The curing bladder provides for simplifying the manufacturing of
pneumatic tires having noise cancelling characteristics. Having the protrusions
shaped as crest and trough as well as the protrusion on the central region as
well as the sidewall regions of the curing bladder results in corresponding
protrusions and pores getting imprinted on an inner liner of the tire that is cured
using the curing bladder. As described above, the protrusions and pores
enable distribution of sound energy and reduce cavity noise without having to
insert any additional sound-absorbing material within the tire cavity.
[0019] The above and other features, aspects, and advantages of the
subject matter will be better explained with regard to the following description and accompanying figures. It should be noted that the description and figures merely illustrate the principles of the present subject matter along with examples described herein and should not be construed as a limitation to the present subject matter. It is thus understood that various arrangements may be devised that, although not explicitly described or shown herein, embody the principles of the present disclosure. Moreover, all statements herein reciting principles, aspects, and examples thereof, are intended to encompass equivalents thereof. Further, for the sake of simplicity, and without limitation, the same numbers are used throughout the drawings to reference like features and components.
[0020] Figure 1 and Figure 2 illustrate a plan view of a curing bladder 100
for manufacturing of pneumatic tires 500 having noise cancelling

characteristics. The figures show a plurality of zig-zag protrusion in a central
region forming parallel channels 101 and oblique channels 202 with respect to
the circumference of the curing bladder 100, in accordance with an
implementation of the present subject matter as in explained below.
[0021] As will be understood the curing bladder 100 is a cylindrical bag of
specially compounded elastomeric material. The curing bladder is a collapsible bladder which is mounted in a lower section of a tire curing press and forms a part of the tire curing press and mold assembly. An uncured pneumatic tire (green unvulcanized tire) is positioned over the curing bladder in the bottom half of the mold. When the mold is closed, pressurized steam, air, hot water, or inert gas (nitrogen) is introduced into the bladder to provide internal heat and pressure for the tire shaping and curing process.
[0022] In accordance with embodiments of the present invention, the curing
bladder 100 provides for curing a pneumatic tire that has noise cancelling characteristics. The curing bladder 100 comprises an exterior wall 102 having a drum-shape, wherein the exterior wall 102 interfaces with the uncured pneumatic tire. The exterior wall 102 has a central region to interface with an inner liner surface located in an interior of a tread portion of the uncured pneumatic tire, and a pair of sidewall regions on either side of the central region. The central region of the exterior wall 102 has a plurality of protrusions shaped as crest and trough. The plurality of protrusions is formed throughout a circumference of the exterior wall. Each of the plurality of protrusions has a plurality of zig-zag protrusions along their respective surface. Further, the pair of sidewall regions comprises a plurality of circular protrusions on an outer surface of either of the sidewall regions. The curing bladder 100 as depicted in Figures 1 and 2 produces a pneumatic tire having noise cancelling characteristics (elaborated later in reference to Figures 5A and 5B).

[0023] In accordance with an embodiment of the present invention, Figure
3 depicts the movement of sound waves 300 passing through the plurality of
zig-zag protrusion in the central region which forms parallel channels 101 with
respect to the circumference of the curing bladder 100. Parallel channel
arrangement here means that the plurality of zig-zag protrusion is parallelly
arranged with respect to the circumference of the curing bladder 100.
[0024] Similarly, in accordance with an embodiment of the present
invention, Figure 4 shows the movement of the sound waves 300 passing through the plurality of zig-zag protrusion in the central region which are formed in an oblique direction with respect to the circumference of the curing bladder 100.
[0025] As will be apparent, the parallel channels 101 of the curing bladder
depicted in Figure 1 imprint corresponding parallel channels 101 on an uncured tire being cured using the bladder depicted in Figure 1. On the other hand, if the curing bladder having oblique channels 202 as depicted in Figure 2 is used to cure a tire, oblique channels 202 get imprinted on the tire when cured.
[0026] The parallel channels 101 as well as the oblique channels 202 serve
to reduce cavity noise. As explained previously, the zig-zag protrusion may form parallel channels 101 or oblique channels 202. The circumferential air moving inside the pneumatic tire 500 of the running vehicle, when passes through the oblique channels 202, the circumferential air, undergoes multiple internal reflections which reduces the cavity noise. When the circumferential air passes through the parallel channels 101, significant amount of sound wave 300 intensity of the air flow inside the pneumatic tire 500 is absorbed which ultimately reduces the cavity noise.
[0027] Figure 5A shows a cross-sectional view of the pneumatic tire 500
having noise cancelling characteristics. The pneumatic tire 500 as shown in

the figure comprises a tread portion and the pair of sidewall portions 502 provided on either side of the tread portion. The tread portion comprises the inner liner surface 501 having the plurality of protrusions shaped as crest and trough 503 having zig-zag pores. The pair of sidewall portions 502 of the pneumatic tire 500 further comprises plurality of circular pores on an inner portion of either of the sidewall portions.
[0028] The central region of the exterior wall 102 of the above-explained
curing bladder 100 has a plurality of protrusions shaped as crest and trough which imparts the plurality of protrusions shaped as crest and troughs 503 throughout a circumference of the inner liner surface 501 of the pneumatic tire 500 during the curing process. Additionally, each of the plurality of protrusions have a plurality of zig-zag pores along their respective surface as shown in Figure 5A. As explained previously, the zig-zag pores may form parallel channels 101 or oblique channels 202 in accordance with different embodiments of the present invention.
[0029] In accordance with an embodiment of the present invention, the
central region of the exterior wall of the curing bladder 100 as depicted in Figures 1 and 2 having a plurality of protrusions shaped as crest and trough 503 imparts an arch shape to the inner liner surface 501 of the pneumatic tire 500 during the curing process as shown in Figure 5B.
[0030] In an example, a height of the plurality of protrusions shaped as
crest and trough 503 with respect to the inner liner surface 501 lies in a range of 1-10 mm. Similarly, in another example, the height of the plurality of protrusions shaped as crest and trough 503 with respect to the inner liner surface 501 lies in a range of 1-100 mm.
[0031] In an example, a length of the each of the plurality of protrusions
measured along the crest and trough 503 lies in a range of 1-500 mm. Similarly, in another example, a length of the each of the plurality of protrusions

measured along the crest and trough 503 lies in a range of 1-1000 mm.
Further, the number of the plurality of crest and trough 503 portions running
throughout an inner circumference in a lateral direction inside the pneumatic
tire 500 may lie in a range of 10-20. The numbers of the crest and trough
portions 503 may vary depending upon the size of the pneumatic tire 500.
[0032] As discussed above, cavity noise in the pneumatic tire 500 is
generated due to vibration of air molecules present inside the pneumatic tire 500 during the running of a vehicle. These vibrations of the air molecules generate sound waves 300 which are perceived as noise to the end user. The maximum air flow, within the tire cavity, happens in the center area or in a region corresponding to the inner liner surface 501 of the pneumatic tire 500 due to centrifugal forces during running of a vehicle. Therefore, the plurality of protrusions in the pneumatic tire 500 are formed throughout the circumference of the inner liner surface 501 in the center area. Also, the protrusions have the zig-zag pores along their surface forming oblique or parallel channels through which the circumferential air running inside a pneumatic tire 500 passes and undergoes multiple internal reflections which significantly reduces the cavity noise of the pneumatic tire 500 by significantly absorbing sound waves 300 intensity of the air flow caused due to centrifugal forces during the running of a vehicle.
[0033] Also, the plurality of protrusions of the curing bladder 100 shaped
as crest and trough 503 imparts an arch shape to the inner liner surface 501 of the pneumatic tire 500 during the curing process which results in significantly reduced air volume which is required for inflating the pneumatic tire 500 which ultimately reduces the airflow inside the pneumatic tire during the running of a vehicle. Hence, the arch-shape of the inner liner surface 501 helps in reducing the cavity noise due to circumferential and vertical flow of the air inside the pneumatic tire 500.Hence, the invention disclosed in the

present disclosure provides low noise levels on all terrain, improved ride comfort, and low vibrations inside the tire cavity.
[0034] Although the subject matter has been described in considerable
detail with reference to certain examples and implementations thereof, other implementations are possible. As such, the present disclosure should not be limited to the description of the preferred examples and implementations contained therein.

I/We claim:
1. A pneumatic tire (500) for a wheel assembly, the pneumatic tire (500)
having noise cancelling characteristics, said pneumatic tire (500) comprising:
a tread portion; and
a pair of sidewall portions (502) provided on either side of the tread
portion, wherein
the tread portion comprises:
an inner liner surface (501) having a plurality of protrusions shaped as crest and trough (503), the plurality of protrusions being formed throughout a circumference of the inner liner surface (501), each of the plurality of protrusions having a plurality of zig-zag pores along their respective surface, and
wherein the pair of sidewall portions (502) comprise:
a plurality of circular pores on an inner portion of either of the sidewall portions.
2. The pneumatic tire (500) as claimed in claim 1, wherein the plurality of circular pores on the inner portion is formed on a shoulder region of the sidewall portions of the pneumatic tire (500).
3. The pneumatic tire (500) as claimed in claims 1, wherein the plurality of protrusions shaped as crest and trough (503) are formed uniformly throughout the circumference of the inner liner surface (501).
4. The pneumatic tire (500) as claimed in claim 1, wherein a height of each of the plurality of protrusions shaped as crest and trough (503) with respect to the inner liner surface (501) lies in a range of 1-10 mm.

5. The pneumatic tire (500) as claimed in claim 1, wherein a height of each of the plurality of protrusions shaped as crest and trough (503) with respect to the inner liner surface (501) lies in a range of 1-100 mm.
6. The pneumatic tire (500) as claimed in claim 1, wherein a length of each of the plurality of protrusions measured along its respective crest and trough (503) lies in a range of 1-500 mm.
7. The pneumatic tire (500) as claimed in claim 1, wherein a length of each of the plurality of protrusions measured along its respective crest and trough (503) lies in a range of 1-1000 mm.
8. The pneumatic tire (500) as claimed in claim 1, wherein a number of the protrusions shaped as crest and trough (503) lies in a range of 10-20.
9. A curing bladder (100) for curing a pneumatic tire (500) having noise cancelling characteristics, the curing bladder comprising:
an exterior wall (102) having a drum-shape, wherein the exterior wall is to interface with an uncured pneumatic tire, the exterior wall having
a central region to interface with an inner liner surface located in an interior of a tread portion of the uncured pneumatic tire, and
a pair of sidewall regions on either side of the central region; wherein
the central region has a plurality of protrusions shaped as crest and trough, the plurality of protrusions being formed throughout a circumference of the exterior wall (102), each of the plurality of protrusions having a plurality of zig-zag protrusions along their respective surface, and wherein

the pair of sidewall regions comprise a plurality of circular protrusions on an outer surface of either of the sidewall regions.
10. The curing bladder (100) as claimed in claim 9, wherein the plurality of zig-zag protrusion in the central region forms oblique channels (202) with respect to the circumference of the curing bladder.
11. The curing bladder (100) as claimed in claim 10, wherein the plurality of zig-zag protrusion in the central region forms parallel channels (101) with respect to the circumference of the curing bladder.