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: HOLLOW INNER TUBE
2. Applicant(s)
NAME NATIONALITY ADDRESS
CEAT LIMITED Indian CEAT Ltd At: Get. Muwala Po: Chandrapura Ta: Halol - 389 350 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 inner tubes for association with the tire and a wheel rim.
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. Some pneumatic tires utilize an inner tube that holds compressed air and provides the tire with its shape.
[0003] Sometimes, the inner tubes get damaged by the rocking of the tire
bead, abrasion with the vehicle's wheel rim, or by the entry of foreign material into the wheel rim. To avoid such damages to the inner tube, tire flaps are usually inserted in the tire to occupy the space between the inner tube and the wheel rim. The tire flaps are crucial in protecting the inner tube from potential damage when they come into contact or rub against the walls of the wheel rim. They also protect the inner tube from getting sucked into the tire's bead toe and immense heat and pressure by avoiding direct contact with the wheel rim, thereby adding life to the inner tube as well as the tire.
BRIEF DESCRIPTION OF DRAWINGS
[0004] 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.
[0005] Figure A is a prior art figure that illustrates a conventional wheel
assembly, in accordance with an implementation of the present subject matter;

[0006] Figure 1 illustrates a cross-sectional view of an inner tube, in
accordance with an implementation of the present subject matter;
[0007] Figure 2 illustrates another cross-sectional view of the inner tube, in
accordance with an implementation of the present subject matter;
[0008] Figure 3 illustrates a wheel assembly, in accordance with an
implementation of the present subject matter;
[0009] Figure 4 is a sectional view of a curing mold for curing the inner tube
shown in Figs. 1 and 2; and
[0010] Figure 5 illustrates a method for curing an inner tube, in accordance
with an example implementation of the present subject matter.
DETAILED DESCRIPTION
[0011] The present subject matter relates to a hollow inner tube designed
for use without a flap in a wheel assembly.
[0012] Many tires for large vehicles such as buses, heavy trucks, and
tractors are designed for use with inner tubes. An inner tube is usually a torus-shaped balloon with a fixed circumference made from an impermeable material such as soft, elastic synthetic rubber, to prevent air leakage. The fixed circumference is generally necessary because adequate cushioning requires that the tire maintain consistent pressure. The inner tubes are inserted into the tire and inflated to retain air pressure. Sometimes, flaps are also used for the proper performance of the tire. A flap is a protective ring interposed between, on one of its sides, the inner tube and, on its other side, rim of a wheel and beads of the tire which is mounted on the rim. A flap may serve to avoid the pinching of the inner tube between the rim and the beads and protects the inner tube from contact with the rim, which may become substantially heated as a result of the operation of the brakes. The flap is manufactured separately from the inner tube, consuming not only time and effort but also additional fuel in the

manufacturing process that may be detrimental to the environment and be
costly.
[0013] As shown in prior art Figure A, usually, the tire 2, inner tube 3, flap
4, and rim 5 all are separate components that form a wheel assembly 1 of a
vehicle. Assembling these separate components is time-consuming and
energy-consuming work. Also, while replacement of the inner tube 3 does not
necessitate the removal of the entire components of the wheel assembly 1, it
is a time-consuming and inconvenient process because, for example, the
placement of the flap 4 may get disoriented while inserting the replacement
inner tube in the tire 2, thereby requiring additional human efforts to correct its
orientation.
[0014] In addition, it is not very convenient to have to use different flaps
depending on the height of rim flange used in a vehicle's wheel assembly.
Moreover, the procurement and maintenance cost of all these separate
components is also high.
[0015] Thus, there exists a need for an improved inner tube that enables a
user to assemble the wheel assembly more quickly and easily.
[0016] Example implementations of a hollow inner tube for use in a wheel
assembly are described. In an example implementation, the wheel assembly
comprises a circular rim and a tire that is mountable on the rim. The tire
includes an annular casing in conjunction with the rim. The inner tube is
interposable in the annular casing between the rim and the tire. The inner tube
comprises an outer circumferential portion that interfaces with the annular
casing of the tire and has a first thickness. The inner tube further comprises an
inner circumferential portion that interfaces with the rim and has a second
thickness. The second thickness is variable across the inner circumferential
portion and is greater than the second thickness.
[0017] The variable thickness of the inner tube across the inner
circumferential portion allows it to serve as tube and flap both in a vehicle's

wheel assembly. Hence, the hollow inner tube of the present subject matter does away with the need to consider or be constrained by present trade-offs of using a separate flap component in the wheel assembly.
[0018] Thus, by using the inner tube of the present subject matter, a
separate flap manufacturing process is avoided, thereby saving overall cost and time. Also, by implementing the teachings of the present subject matter, the tire manufacturing process may be made more energy-efficient. Further, the time and efforts required in assembling different components of the wheel assembly may also be reduced significantly.
[0019] The above-mentioned implementations are further described herein
with reference to the accompanying figures. It should be noted that the description and figures relate to exemplary implementations and should not be construed as a limitation to the present subject matter. It is also to be understood that various arrangements may be devised that, although not explicitly described or shown herein, embody the principles of the present subject matter. Moreover, all statements herein reciting principles, aspects, and embodiments of the present subject matter, as well as specific examples, are intended to encompass equivalents thereof.
[0020] Figure 1 illustrates a cross-sectional view of a hollow inner tube 100
for use in a wheel assembly (shown in Figure 3), in accordance with an implementation of the present subject matter. In an example implementation, the wheel assembly may comprise a circular rim (shown in Figure 3) and a tire (shown in Figure 3) mountable on the rim. The tire includes an annular casing in conjunction with the rim. The inner tube 100 is interposable in the annular casing present between the rim and the tire. The annular casing of the tire may be understood as a space formed between its sidewalls and radial underside of the ground engaging portion.
[0021] The inner tube 100 has an outer circumferential portion 102 that
extends from a first end 112 to a second end 114. Upon inserting the inner tube

100 into the tire, its whole outer circumferential portion 102, extending between
the first end 112 and the second end 114, fits inside the annular casing of the
tire. The outer circumferential portion 102 has a first thickness 104 which is
substantially uniform from the first end 112 to the second end 114.
[0022] The inner tube 100 further comprises an inner circumferential portion
106 that when assembled in the wheel assembly sits on flanges of the rim. The inner circumferential portion 106 forms a part of the inner tube 100 that is contained within a crescent shape box as shown in Figure 1. The inner circumferential portion 106 has a second thickness 108. As shown in Figure 1, the second thickness 108 is greater than the first thickness 104 across the inner circumferential portion 106. The second thickness 108 is such that it creates a buffer layer in the inner tube 100 towards its inner circumferential portion 106 sufficient enough to prevent pinching and wear at contact points of the inner circumferential portion 106 and the flange of the rim, thereby effectively preventing the generation of a puncture due to a pierced damage to the inner tube 100 by a nail or the like and of shock puncture due to riding of the tire over an obstacle. The second thickness 108 also prevents the inner tube 100 from being trapped between the bead of the tire and the rim.
[0023] An inflation valve 110 for controlling the inflation of the inner tube 100
is also provided. As shown in Fig. 1, the inflation valve 110 may be connected towards the inner circumferential portion 106 through a groove provided on an outer layer 116 of the inner tube 100. The inflation valve 110 is configured to inflate the hollow inner tube 100 by filling air into a circumferential space formed by an inner layer 118 of the inner tube 100.
[0024] Figure 2 depicts another view of the inner tube 100 of the wheel
assembly, in accordance with an implementation of the present subject matter. As shown in Figure 2, the inner circumferential portion 106 may be divided into three sub-portions namely center portion 202, reinforced portion 204-1, 204-2, and shoulder portion 206-1, 206-2.

[0025] An approximate value of the thickness of the center portion 202, the
reinforced portion 204-1, 204-2, and the shoulder portion 206-1, 206-2 for different stock keeping unit (SKU) groups of the inner tube 100 may be given by the table below:

SKU Center portion Reinforced portion Shoulder portion

Maximu m Minimu m Maximu m Minimu m Maximu m Minimu m
SKU1 5.5 4.5 8 7 6.1 5.1
SKU2 6.7 5.7 10.5 9.5 7.9 6.9
SKU3 5.6 4.6 12.7 11.7 8.5 7.5
SKU4 5.7 4.7 12.6 11.6 8.3 7.3
SKU5 5.7 4.7 12.6 11.6 8.3 7.3
[0026] Herein all the SKU groups from SKU1 to SKU5 may have varying
applications. For example, the SKU1 may only be used in the wheel assembly of a light truck, the SKU2 may only be used in the wheel assembly of a two-wheeler, etc.
[0027] It may also be understood that the value of the second thickness 108
may vary depending upon the application of the inner tube 100. For example, the second thickness 108 of the inner tube 100 when used in a wheel assembly of a bicycle may be less than that when used in a wheel assembly of a heavy-duty vehicle such as a truck or bus.
[0028] This varying thickness of the inner tube 100 across its inner
circumferential portion 106 allows this portion of the inner tube 100 to conform to the shape of the rim flange, thereby preventing the failure of the inner tube 100 resulting from abrasion at the junction of the tire and rim. Also, since the second thickness 108 is more than the first thickness 104, the inner tube 100

exhibits a shock-absorbing effect which further effectively averts possible
cracks in the inner tube 100 that may be caused due to rim striking.
[0029] Additionally, even if a part of the inner circumferential portion 106 of
the inner tube 100 that remains in a contact with the rim is damaged by the rim
striking, it may not result in a leakage of the air or blowout of the inner tube 100
because the extra thickness of the circumferential portion 104 prevents the
crack from reaching to the innermost layer of the inner tube 100 that holds the
air. The circumferential portion 104 of the inner tube 100 is such that it allows
the inner tube to serve as a flap, thereby affording ease in the tire fitment by
reducing the number of components required in a wheel assembly of a vehicle.
The inner tube 100 of the present subject matter also helps in reducing the tube
maintenance frequency and tube related failures due to the use of flaps.
[0030] Further, in an example embodiment of the present subject matter,
the outer circumferential portion 102 and the inner circumferential portion 106 may be made up of a continuous rubber profile, thereby forming the contiguously torus-shaped inner tube 100.
[0031] Figure 3 illustrates a wheel assembly 300, in accordance with an
implementation of the present subject matter. The wheel assembly 300 includes a tire 302, which is similar to the tire discussed in reference to Figs. 1 to 2. The inner tube 100 is such that it occupies the space created by an inner side 304 of the tire 302 and a rim 306 of the wheel assembly 300. The rim 306 is similar to the rim discussed in reference to Figs. 1 to 2. As shown in Figure 3, there is no need to include a separate flap in the wheel assembly 300 of the present subject matter as the second thickness 108 of the inner tube 100 itself acts as a flap. Thus, the inner tube 100 helps eliminate the need to use the flap component from the wheel assembly 300, thereby reducing hassle in assembling the different components of the wheel assembly 300 and their maintenance. It may also help in eliminating tube related failures caused by flap pinching.

[0032] Next, referring to Figure 4, a curing mold 400 is described. The curing
mold 400 is provided with a recess 402 for housing an uncured inner tube, such as the inner tube 100 explained with respect to Figs. 1 to 3, during the curing process. As shown in Figure 4, the recess 402 is formed by aligning a top mold portion 402-1 and a bottom mold portion 402-2 of the curing mold 400 over each together. The recess 402 may be divided into a top recess portion 404-1 and a bottom recess portion 404-2. The profile of the top recess portion 404-1 is such that it may accommodate the outer circumferential portion 102 of the inner tube 100 when placed inside the recess 402 that is formed by aligning the top mold portion 402-1 and the bottom mold portion 402-2. Further, as shown in the shaded region of Figure 3, the profile of the bottom recess portion 404-2 is such that it may accommodate the inner circumferential portion 106 of the inner tube 100 when placed inside the recess 402.
[0033] The bottom recess portion 404-2 may be shaped to accommodate
the second thickness 108 of the inner tube 100 that is variable across the inner circumferential portion 106. For example, as shown in Fig 3., a shaded region 406 of the bottom recess portion 404-2 is profiled in such a way that it conforms to the shape of the second thickness 108 of the inner tube 100.
[0034] The curing mold 400 may further comprise a curing unit (not
illustrated) that may be configured to supply either heat or pressure or both to the curing mold 400 during the curing process.
[0035] A method 500 of curing the inner tube 100 is depicted in Figure 5. In
an example step 502, an uncured inflated inner tube, such as the inner tube 100 discussed with respect to Fig. 1-4, may be placed in a recess 402 of the curing mold 400 that is formed by the top recess portion 404-1 and the bottom recess portion 404-2. Once placed inside the recess 402, the uncured inner tube 100 may be cured by supplying either heat or pressure or both to the outer circumferential portion 102 and the inner circumferential portion 106.

[0036] 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 hollow inner tube (100) for a wheel assembly (300), the wheel assembly
(300) comprising a circular rim (306) and a tire (302) to be mounted on the rim
(306), the tire (302) defining an annular casing in conjunction with the rim (306),
the hollow inner tube (100) being interposable in the annular casing between
the rim (306) and the tire (302), the hollow inner tube (100) comprising:
an outer circumferential portion (102) interfacing the annular casing of the tire (302), the outer circumferential portion (102) having a first thickness (104); and
an inner circumferential portion (106) interfacing the rim (306), the inner circumferential portion (104) having a second thickness (108), the second thickness being variable across the inner circumferential portion (104),
wherein the first thickness (104) is less than the second thickness (108).
2. The hollow inner tube (100) as claimed in claim 1, wherein the first thickness (104) lies in a range of 1.3-3.2 mm.
3. The hollow inner tube (100) as claimed in claim 1, wherein the first thickness (104) is uniform across the outer circumferential portion (102).
4. The hollow inner tube (100) as claimed in claim 1, wherein the second thickness (108) lies in a range of 4.5-12.7 mm.
5. The hollow inner tube (100) as claimed in any of the preceding claims 1-4, wherein the outer circumferential portion (102) and the inner circumferential portion (104) are made up of a continuous rubber profile.

6. The hollow inner tube (100) as claimed in claim 1, further comprising an inflation valve (110) connected towards the inner circumferential portion (104) and configured to inflate the hollow inner tube (100).
7. A method (500) for curing a hollow inner tube (100) for a wheel assembly (300), the method (500) comprising:
placing (502) an uncured inflated inner tube (100) having an outer
circumferential portion (102) and an inner circumferential portion (106) in a
recess (402) of a curing mold (400), wherein
the outer circumferential portion (102) has a first thickness (104) and the inner circumferential portion (104) has a second thickness (108), the second thickness being variable across the inner circumferential portion (104), and wherein the first thickness (104) is less than the second thickness (108); and curing the uncured inner tube (100) by providing at least one heat and
pressure to the outer circumferential portion (102) and the inner circumferential
portion (106).
8. A curing mold (400) for curing a hollow inner tube (100) for a wheel
assembly (300), the curing mold (400) comprising:
a recess (402) to hold an uncured inflated inner tube (100) having an outer circumferential portion (102) and an inner circumferential portion (106), wherein the outer circumferential portion (102) has a first thickness (104), and the inner circumferential portion (104) has a second thickness (108), the second thickness being variable across the inner circumferential portion (104), and wherein the first thickness (104) is less than the second thickness (108); and
a curing unit to provide at least one of heat and pressure to the outer circumferential portion (102) and the inner circumferential portion (106).

9. The curing mold (400) as claimed in claim 8, wherein the curing mold
(400) comprises a top recess portion (404-1) for accommodating the outer
circumferential portion (102) and a bottom recess portion (404-2) for
accommodating the inner circumferential portion (106).
10. The curing mold (400) as claimed in claim 9, wherein the bottom recess
portion (404-2) is shaped to accommodate the second thickness (108) being
variable across the inner circumferential portion (104).