NON-PNEUMATIC TYRE
Technical field
The subject matter described herein, in general, relates to non-pneumatic tyres for non-motorized vehicles such as bicycles. Background
At present, vehicles employ a variety of tyres such as pneumatic and non-pneumatic tyres. Pneumatic tyres have been known for many years. A majority of the vehicles use pneumatic tyres either in tube or tubeless form. However, a common problem associated with pneumatic tyres is that of air loss. Air loss can occur due to a puncture or a defective valve or any other defect in the tube or the tyre. Consequently, the cost of maintenance, and more importantly, the time lost due to defective tubes is high for such tyres.
Non-pneumatic tyres, as the name suggests, do not suffer from the problem of air loss. Common non-pneumatic tyres employ either ribs of closed-cell polyurethane foam or are filled with polymers (plastic) instead of air. A popular example of such a non-pneumatic tyre is the 'Tweel' developed by Michelin for automobiles. These tyres often suffer from higher rolling friction, poor suspension and from high noise and heat generation.
Another form of non-pneumatic tyres provide for a tyre having discontinuous leaf springs along the rim of the wheel for supporting portions of the crown portion of the tyre. This tyre suffers from heating up and deformation of the tyre during use resulting in high maintenance. Additionally, the cost of manufacturing such tyres is high. Therefore, an effective low-cost non-pneumatic tyre for vehicles, especially vehicles designed for low carrying loads is absent. Summary
The present invention relates to non-pneumatic tyres for vehicles, including but not limited to non-motorized vehicles. The non-pneumatic tyres as provided are particularly suitable for vehicles designed for low carrying loads and operating at moderate speeds.

In one embodiment, a tyre having a crovm portion and two sidewalls integrated to the crown portion is embedded with a continuous load-bearing high flexibility strip in the crown portion. In another embodiment, the load bearing high flexibility strip is placed on the inner surface of the crown portion. The sidewalls of the tyre are made of nylon-reinforced thread of suitable strength to maintain the shape of the strip and to prevent the tyre from collapsing onto the rim.
The non-pneumatic tyre of the present subject matter provides for low cost and maintenance. Further, using the non-pneumatic tyre needs no additional modification in the existing construction of the non-motorized vehicles. The non-pneumatic tyre may be assembled onto a non-motorized vehicle in the same manner as a conventional tyre. Also, a conventional tyre may be converted into a non-pneumatic tyre as described above.
This summary is provided to introduce simplified concepts related to a non-pneumatic tyre, which is fiirther described below in the detailed description. This summary is not intended to identify essential features of the claimed subject matter, nor is it intended for use in determining the scope of the claimed subject matter.
Brief Description of Drawings
Fig. 1 illustrates cross-sectional view of a non-pneumatic tyre, in accordance with one embodiment of the present invention.
Fig. 2 illustrates side view of the non-pneumatic tyre of Figure 1, in accordance with one embodiment of the present invention.
Fig. 3 illustrates the non-pneumatic tyre of Figure 1 fitted on a tyre rim, in accordance with one embodiment of the present invention.
Fig. 4 illustrates cross-sectional view of the non-pneumatic tyre, in accordance with one embodiment of the present invention. Detailed description
Vehicles around the world are fitted with various forms of tyres. Pneumatic tyres have a tyre body and a tube filled with pressurized air. The tyre body structurally includes a crown portion with treads, and sidewalls integrated with the crown portion to give a U-shaped cross-section to the tyre. The air-filled tube is placed inside the tyre body and the tyre body is fitted onto a tyre rim. The pneumatic tyres also work well for the vehicles

carrying small loads and running at low speeds. However, the pneumatic tyres are bound to lose air pressure, as discussed earlier, which causes inconveniences and increase the cost of maintenance.
The present subject matter relates to a non-pneumatic tyre, in particular for light weight, low load carrying, low speed vehicles, such as bicycles. One embodiment of the tyre, the non-pneumatic tyre includes a continuous highly elastic and strong load bearing strip of suitable material placed throughout the crown portion of the tyre. In another embodiment of the tyre, the strip is made of spring steel. In another embodiment of the tyre, the strip is narrow in width that allows the strip to retain the elastic nature and maintain an optimal flattening of the tyre at the time of transportation. Further, the strip may be made having a curved cross-section, taking the shape of the crown portion, to allow the tyre to have optimal contact with the road surface and thereby keeping the rolling friction low.
In another embodiment of the tyre, the highly elastic load bearing continuous strip may be placed at the irmer surface of the crovm portion. Further, the width of the strip may be substantially equal to the width of the crown portion such that the strip is confined firmly within the sidewalls of the tyre. In another embodiment, the crown portion and the sidewalls may be made with higher volume of rubber to prolong the life of the tyre from wear and tear.
In one embodiment of the tyre, the circular symmetry of the tyre is maintained by the reinforced nylon threaded sidewalls and crown portion. These sidewalls maintain the circular shape of the tyre by restricting the distortion of the tyre into an elliptical shape at the time of loading. The nylon threaded crown portion restricts the deformation in the tyre in the form of peaks and troughs within the tyre during loading.
With the load-bearing continuous strip placed within and/or along the crown portion, the reinforced sidewalls prevent the crovra portion from coming in contact with the rim of the tyre for suitable loads. This ensures that the load impacts or shocks are not transferred to the rim and therefrom to the vehicle. Rather, they are absorbed within the tyre body. Thus, this type of non-pneumatic tyre provides for a smooth ride.
The non-pneumatic tyre shall be explained in greater detail with respect to Figs. 1-4. While aspects of the described systems can be implemented in a number of different

configurations, the embodiments are described in the context of the following exemplifying mechanisms.
Fig. 1 illustrates a cross-sectional view of a non-pneumatic tyre 1 in accordance with an embodiment of the present subject matter. The tyre 1 includes a crown portion 2 and sidewalls 3 integrally connected on either sides of the crown portion 2. The crown portion 2 of the tyre 1 has treads. It is the part of the tyre 1 that comes in contact with the surface on which the tyre 1 rolls. Each sidewall 3 has a first end 4 and a second end 5. The sidewalls 3 are integrated with the crown portion 2 via the first ends 4 to give a substantially U-shaped cross-section to the tyre 1. The tyre 1 is fitted on a tyre rim 7 through the second ends 5 of the sidewalls 3.
The tyre 1 further includes a continuous strip 6 placed circumferentially throughout the crown portion 2 as shown in Fig. 2. The continuous strip 6 bears external loads on the tyre. The external load could be resulted by weight of the vehicle, weight of rider(s) and/or weight of objects kept on the vehicle, etc. The non-pneumatic tyre 1, according to the subject matter, effectively dampens the load impacts experienced the tyre 1.
In one embodiment, the load-bearing continuous strip 6 may be embedded in the crown portion 2 of the tyre 1. The continuous strip 6 can be embedded in the crown portion 2 while manufacturing the tyre 1.
In one implementation, the crown portion 2 and the sidewalls 3 of the tyre 1 are made of a nylon-thread reinforced rubber. The sidewalls 3 flex outwards under the external loads. The nylon-threads reinforced in the sidewalls 3 provide strength to the sidewalls 3 and prevent the tyre 1 from bursting under the heavy loads. Apart fi-om this, the flexing of the sidewalls 3 and the strength provided by the reinforced nylon-threads prevent the crown portion 2 embedded with the continuous strip 6 collapse under the application of external loads. With this the crown portion 2 does not come in contact with the rim 7, and the shock loads are not transmitted to the rim 7 and the vehicle. The shock loads are rather damped within the tyre 1.
In one embodiment, the load-bearing continuous strip 6 has an optimum width such that it can effectively bear the external loads without causing excessive flattening of the crown portion 2. Excessive flattening of the crown portion 2 may often result in an

increase the contact surface area between the crown portion 2 of the tyre 1 and road surface on which the tyre 1 rolls, which in turn may cause an increase the frictional forces. The increased fiction leads to an increase the effort of the rider to ride the vehicle. In one embodiment, the width of the continuous strip 6 is nearly equal or less than the width of the crown portion 2.
Further, under the external loads, the section of the tyre that is in contact with the road surface underneath presses inwards towards the rim to deform the section of the tyre. The extent of deformation depends on the magnitude of external load on the tyre, however as mentioned earlier, the crown portion 2 does not come in contact of the rim 7. Along with the section of the tyre which is in contact with the surface, the portion of the continuous strip within the section also bends and deforms in shape. As the tyre 1 rolls, the deformed section of the tyre, looses its contact with the road surface, and regains its shape. More importantly, the bent portion of the continuous strip 6 also regains its shape. This is necessary, to achieve uniform and smooth rolling of the tyre 1. Accordingly, to achieve this, the continuous strip 6 is made of a material having a high bending rigidity. The material ftirther possesses properties like high Young's modulus, high yield strength, good shape retention property, etc.
In one embodiment, the load-bearing continuous strip 6 is made of spring steel. Spring steel possesses high elastic strength and good shape retention property and at the same time is cost effective and easily available.
Further, in one embodiment, the continuous strip 6 may have a curved cross-section as shown in Fig. 1. The strip 6 takes the shape of the crown portion 2 of the tyre 1. The continuous strip 6 with the curved cross-section reduces the flattening of the tyre 1. This helps in maintaining an optimal contact surface area between the crown portion 2 of the tyre 1 and the road surface decreases, which, as a result controls the frictional forces.
The non-pneumatic tyre 1, according to the subject matter, is structurally similar to a conventional tyre from outside and can be easily fitted on a conventional tyre rim just like a conventional tyre. Further, the tyre 1 provides a smooth ride.
Fig. 3 shows the non-pneumatic tyre 1 fitted on the tyre rim 7. Each sidewall 3 of the tyre 1 comprises at least one beading 8 reinforced in the second end 5 of the sidewall

3. In one embodiment, the beading 8 is made of steel. The second ends 5 of the sidewalls 3 with the beading 8 are fitted into a curved cross-section 9 of the rim 7, as shown in Fig. 3. The headings 8 provide a tight fit of the tyre 1 on the rim 7.
Fig. 4 represents another embodiment of the present subject matter, showing the non-pneumatic tyre 1 with the load-bearing continuous strip 6 placed along an inner surface 10 of the crown portion 2. In one embodiment, the width of the strip 6 is nearly equal to the width of the crovm portion 2, so that the strip 6 fits tightly within the sidewalls 3. The tight connection of the continuous strip 6 at the inner surface 10 of the crown portion 2 is also due to the tension in the tyre body when the continuous strip 6 is assembled inside. Further, when the strip 6 is placed along the inner surface 10 of the crown portion 2, the inner surface of the strip 6 will be exposed to atmosphere.
A conventional tyre can be converted to the non-pneumatic tyre 1 of the present subject matter. For this, the continuous strip 6 can be retrofitted in the body of a conventional tyre. The tyre body of a conventional tyre is cut into two halves without removing headings 8 of the tyre. The continuous strip 6, of length sufficient to cover the circumference of the tyre 1 at least once, is inserted in one of the halves of the tyre body. This leaves one half of the continuous strip 6 inside the tyre body and other half of the continuous strip 6 exposed. The continuous strip 6 is inserted in such a way that it presses along the inner surface 10 of crown portion 2 of the tyre 1. The width of the continuous strip 6 is nearly equal to the width of the crown portion 2 of the tyre 1, so that it fits tightly within the sidewalls 3. The half of the tyre body with the inserted continuous strip 6 is fitted on a tyre rim 7 through the headings 8. After this, other half of the tyre body is assembled over the exposed continuous strip 6. The resulting tyre is the non-pneumatic tyre 1 retrofitted with the load-bearing continuous strip 6, as shown in Fig. 4. The ride of vehicle provides by this type of tyre is smooth. In a preferred embodiment, to avoid flattening of the tyre 1, the cross-section of the retrofitted continuous strip 6 may be curved, taking the shape of the crovm portion 2.
Although the embodiments have been described in language specific to structural features, it is to be understood that the subject of the appended claims is not necessarily limited to the specific features described. Rather, the specific features are disclosed as exemplifying implementations for the claimed subject matter.

We claim:
1. A non-pneumatic tyre (1) comprising:
a crown portion (2); and
side walls (3) integrated with said crown portion (2); characterized in that,
said crown portion (2) includes a load-bearing continuous strip (6) placed circumferentially throughout said crown portion (2).
2. The non-pneumatic tyre (1) as claimed in claim 1, wherein the strip (6) is embedded in the crown portion (2).
3. The non-pneumatic tyre (1) as claimed in claim 1, wherein the strip (6) is placed along an inner surface (10) of said crown portion (2).
4. The non-pneumatic tyre (1) as claimed in any of the preceding claims, wherein the strip (6) is made of material having a high bending-rigidity.
5. The non-pneumatic tyre (1) as claimed in claim 4, wherein the strip (6) is made of spring steel.
6. The non-pneumatic tyre (1) as claimed in any of the preceding claims, wherein the strip (6) has a curved cross-section.
7. The non-pneumatic tyre (1) as claimed in claim 1, wherein the sidewall 3 has a first end (4) and a second end (5), and the sidewall (3) comprises at least one beading (8) reinforced in the second end (5).
8. The non-pneumatic tyre (1) as claimed in claim 1, wherein the crown portion (2) and the sidewalls (3) are made of a nylon thread reinforced rubber.

9. A bicycle comprising at least one non-pneumatic tyre (1), wherein the tyre (1)
comprising:
a crown portion (2); and
sidewalls 3 coimected to said crown portion (2),
characterized in that,
said crown portion (2) includes a load-bearing continuous strip (6) placed circumferentially throughout said crown portion (2).
10. A non-motorized vehicle comprising at least one non-pneumatic tyre (1), wherein
the tyre (1) comprising:
a crown portion (2); and
sidewalls 3 connected to said crown portion (2),
characterized in that,
said crown portion (2) includes a load-bearing continuous strip (6) placed circumferentially throughout said crown portion (2).

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