Wheel Assembly for a Motor Vehicle

FIELD OF THE INVENTION

[001] The present invention generally relates to a straddle type motor vehicle and more particularly to a wheel assembly for the vehicle. BACKGROUND OF THE INVENTION

[002] A wheel assembly generally has a wheel rim and a wheel hub. The wheel hub has a circular contour and is detachably attached to the wheel rim. In a drum brake system, the wheel hub encompasses brake cylinders and brake pads and is circumferentially mounted on a backing plate. The backing plate being mounted on a drive shaft, rotates axially in response to engine output. When brakes are applied, the brake pads mounted on the back plate frictionally engage with inner wall of the wheel hub thereby slowing down and eventually stopping rotation of the wheel.

[003] Due to frequent braking and frictional engagement with the brake pads, the wheel assembly, more particularly, the wheel rim and the wheel hub are exposed to an increased stress. This eventually results in cracking of either the wheel rim or the wheel hub. Further, the wheel assembly is also frequently subjected to over-heating and increased hoop stress. Hence, several attempts have been made towards wheel assemblies in order to overcome these issues. In one such attempt, the wheel hub is made of a metal like cast iron. Although, cast iron does not succumb to stress and has heat-conductive and wear- resistant properties, however, cast iron wheel hubs increase overall weight of the wheel which directly affects mileage of the vehicle. Moreover, the cast iron is prone to cracks. In order to decrease the overall weight, an alloy based wheel hub is used, more particularly aluminum based wheel hub. However, alloy based wheel hubs increase an overall cost of manufacturing the wheel assemblies which is undesirable. Further, in order to reduce the costs, sheet metal is used to manufacture the wheel hub. However, sheet metal has insufficient mass, volume, surface area and thermal conductivity when compared to the alloy based wheel hub.

[004] Thus, there is a need in the art for a wheel assembly which addresses at least the aforementioned problems.

SUMMARY OF THE INVENTION

[005] The present invention is directed to a wheel assembly for a motor vehicle. The wheel assembly has a wheel rim composed of a first material; and a wheel hub composed of a second material, the wheel hub being detachably attached to the wheel rim and configured to dissipate heat generated while applying brakes to the motor vehicle.

[006] In an embodiment of the present invention, the wheel hub has a disk having an inner face facing a backing plate of the drum brake and an outer face configured to dissipate heat generated in the wheel hub; and an annular wall extending from the disk and configured to dissipate heat generated in the wheel hub. [007] In another embodiment of the present invention, the outer face of the disk of the wheel hub comprises plurality of cooling fins extending from periphery of the disk of the wheel hub towards center of the disk of the wheel hub.

[008] In an embodiment of the present invention, the plurality of cooling fins comprises plurality of staggered fins. In another embodiment, first end of at least one of the plurality of staggered cooling fins is located on a first imaginary circle, wherein radius of the first imaginary circle varies between 1mm to 70mm from a rotational axis of the wheel hub.

[009] In a further embodiment of the present invention the plurality of cooling fins comprises plurality of non-staggered cooling fins. In an embodiment, first end of at least one of the plurality of non-staggered cooling fins is located on a first imaginary circle, wherein radius of the first imaginary circle varies between 1mm to 70mm from a rotational axis of the wheel hub.

[010] In yet another embodiment of the present invention, the outer face of the disk of the wheel hub has at least one annular fin. In another embodiment, the inner face of the disk of the wheel hub comprises at least one annular groove.

[011] In a further embodiment, the annular wall of the wheel hub extends to form an annular ridge around the periphery of the disk of the wheel hub. In another embodiment, the annular ridge is discontinuous.

[012] In an embodiment, the first material is sheet metal. In another embodiment, the second material is alloy.

[013] In an embodiment of the invention, the wheel rim has plurality of locking receptacles along its inner circumference. In another embodiment, the wheel hub has plurality of fixating loops around its periphery corresponding to the locking receptacles of the wheel rim. In yet another embodiment, the locking receptacles and the fixating loops receive fixating means for detachably attaching the wheel hub to the wheel rim.

BRIEF DESCRIPTION OF THE DRAWINGS

[014] Reference will be made to embodiments of the invention, examples of which may be illustrated in accompanying figures. These figures are intended to be illustrative, not limiting. Although the invention is generally described in context of these embodiments, it should be understood that it is not intended to limit the scope of the invention to these particular embodiments.

Figure 1 shows a side view of a motor vehicle in accordance with an embodiment of the invention.

Figure 2 shows a rear side perspective view of the motor vehicle in accordance with an embodiment of the invention.

Figure 3 shows an exploded view of a rear wheel assembly in accordance with an embodiment of the invention. Figure 4a shows perspective view of a wheel hub in accordance with an embodiment of the invention.

Figure 4b shows front view of a wheel hub in accordance with an embodiment of the invention.

Figure 5a shows a front view of the wheel hub in accordance with an alternative embodiment of the invention.

Figure 5b shows a perspective view of the wheel hub in accordance with an alternative embodiment of the invention.

Figure 6a shows front view of the inner face of the wheel hub in accordance with an embodiment of the invention. Figure 6b shows a partial cut section perspective view of the inner face of the wheel hub in accordance with an embodiment of the invention.

Figure 7 shows a comparative temperature graph of the wheel assembly of the present invention versus a conventional wheel assembly. DETAILED DESCRIPTION OF THE INVENTION

[015] The present invention relates to a wheel assembly of a motor vehicle.

[016] Figure 1 illustrates a right-side view of an exemplary motor vehicle 100. The vehicle 100 comprises a main frame 10 having a head tube 12. Towards front side, the motor vehicle 100 has one or more front suspensions 14 connected to a front wheel 16 which is further connected to a handlebar assembly 18, which forms a steering assembly of the motor vehicle 100. The steering assembly has a pair of rear view mirrors 36a, 36b. The steering assembly is rotatably disposed about the head tube 12. The main frame 10 extends rearwardly downward from the head tube 12 and has a bent portion thereafter extending substantially in a longitudinal direction towards rear side, in a front rear direction, of the motor vehicle 100.

[017] The motor vehicle 100 further has an internal combustion (IC) engine 20. In the present embodiment, the IC engine 20 is swingably connected to the main frame 10. Towards rear side, the motor vehicle 100 has a rear wheel 210 mounted on a wheel rim 220 of a wheel assembly 200.

[018] As shown in Figures 1 and 2, the motor vehicle 100 also has an exhaust system 26 extending rearwards from the IC engine 20. In addition, the vehicle 100 has a rear fender 28 covering at least a portion of the rear wheel 210 and is positioned upwardly of the rear wheel 210. Further, the motor vehicle 100 has a seat assembly 32 supported by the main frame 10. The seat assembly 32 is hingedly openable. The motor vehicle 10 has a floorboard 34 wherein a rider can operate the vehicle 100 in a seated position by resting feet on the floorboard 34. Further, the floorboard 34 is capable of carrying loads. In addition, a utility box is disposed below the seat assembly 32 and is supported by the main frame 10. A fuel tank (not shown) is disposed adjacent to the utility box. Furthermore, the vehicle 100 comprises of plurality of electrical and electronic components including a headlight assembly 38, a taillight assembly 30, a transistor-controlled ignition (TCI) unit (not shown), an alternator (not shown), a starter motor (not shown). The motor vehicle 100 is thus made to stay in a riding ready position over a center stand 40. [019] Referring to Figures 2 and 3, the wheel assembly 200 of the present invention has a wheel rim 220 and a wheel hub 300. The wheel hub 300 is detachably attached to the wheel rim 220 using plurality of fixating means 230 such as nuts and bolts. Further, the wheel hub 300 is configured to dissipate heat generated in the wheel hub 300 while applying brakes to the motor vehicle 100. In the present invention, the wheel rim 220 is made of a first material, whereas the wheel hub 200 is made of a second material. In an embodiment of the invention, the first material is sheet metal, whereas the second material is alloy.

[020] Referring to Figures 4a and 4b, in an embodiment of the invention, the wheel hub 300 has a disk 310. The disk 310 has an axial hole in center 314 which receives a driving shaft (not shown) of the vehicle 100. The disk 310 has an inner face 310b (shown in Figures 5a, 6a and 6b) and an outer face 310a. The inner face 310b faces a backing plate (not shown) of the drum brake, while the outer face 310a of the disk 310 is configured to dissipate heat generated in the wheel hub 300.

[021] Generally, a drum brake uses frictional forces against a rotating wheel hub in order for the wheel assembly and consequently the tyre mounted thereon to slow down and eventually stop. Continued friction between two surfaces always generates an increased amounts of heat. Thus, as described hereinbefore, in an embodiment, the outer face 310a of the disk 310 is configured to dissipate the heat generated from such frictional engagements. As shown in Figures 4a, 4b, 5a, and 5b in an embodiment of the invention, the outer face 310a of the disk 310 is configured to have cooling fins.

[022] Referring to the embodiment depicted in Figures 4a and 4b, the outer face 310a of the disk 310 of the wheel hub 300 has plurality of cooling fins. These are staggered cooling fins 318. The staggered cooling fins 318 extend from a periphery 312 of the disk 310 towards center 314 of the disk 310. In an embodiment of the invention, first end of at least one of the staggered cooling fins 318 is located on a first imaginary circle, wherein radius of the first imaginary circle varies between 1mm to 70mm from a rotational axis of the wheel hub 300. [023] In another embodiment depicted in Figure 5a, the outer face 310a of the disk 310 has plurality of non-staggered cooling fins 320. The non-staggered cooling fins 320 are substantially perpendicular to the periphery 312 of the disk 310 and extend from the periphery 312 towards the center 314 of the disk 310. In an embodiment of the invention, first end of at least one of the non-staggered cooling fins 320 is located on a first imaginary circle, wherein radius of the first imaginary circle varies between 1mm to 70mm from a rotational axis of the wheel hub 300.

[024] In a further embodiment of the invention, and referring to Figure 5b, the outer face 310a of the disk 310 is configured to have at least one annular fin 322. The annular fin 322 is concentric with the axial hole in the center 314. In yet another embodiment, and as shown in Figures 6a and 6b, the inner face 310b of the disk 310 is configured to have at least one annular groove 324. In the embodiment, the annular groove 324 is concentric with the axial hole in the center 314. It may be noted that the configurations of the outer face 310a are not limited to embodiments described hereinbefore. Further, it will be apparent to a person skilled in art that the outer face can be configured by way of aforementioned embodiments in isolation or in combination.

[025] Further, the wheel hub 300 of the present invention has an annular wall 350. The annular wall 350 extends from the disk 310 and circumferentially engages with the backing plate of the drum brake. While braking, inner surface of the annular wall 350 frictionally engages with brake pads (not shown) of the drum brake. In the present invention, the annular wall 350 is configured to dissipate heat generated in the wheel hub 300. Referring to Figures 4a and 6b, in an embodiment of the invention, the annular wall 350 is configured to extend to form an annular ridge 360 around the periphery 312 of the disk 310. In yet another embodiment of the invention, the annular ridge 360 is discontinuous.

[026] Further, referring to Figures 2, 3, 4a, 4b, 5a, 5b, 6a, and 6b in an embodiment, the wheel hub 300 has plurality of fixating loops 380 around its periphery. Referring to Figure 3, the wheel rim 220 has plurality of locking receptacles 240 along its inner circumference. The plurality of locking receptacles 240 of the wheel rim 220 correspond to the plurality of fixating loops 380 of the wheel hub 300. As shown in Figures 2 and 3, the wheel hub 300 is detachably attached to the wheel rim 220, whereby the fixating loops 380 and locking receptacles 240 receive a plurality of fixating means 230 such as nuts and bolts.

[027] Referring now to Figure 7, which is a comparative temperature graph. The graph has two bars viz., A representing the wheel assembly of the present invention and B representing a conventional wheel assembly. As seen in various experiments, there was a substantial heat dissipation in the wheel assembly of the present invention. Advantageously, owing to the cooling fins, heat dissipation increases manifold since the cooling fins increase surface area and improve air circulation. This in turn improves brake performance and handling of the vehicle. Further, due the annular ring on the outer face and/or due to the annular groove on the inner face, the wheel hub has an increased capacity towards bearing excess hoop stress without undergoing deformations. Additionally, the disk and the annular ring being made of different materials, decreases overall weight of the wheel assembly substantially. [028] While the present invention has been described with respect to certain embodiments, it will be apparent to those skilled in the art that various changes and modification may be made without departing from the scope of the invention as defined in the following claims.