DESC:FIELD OF INVENTION
[0001] The present invention relates to a multi-wheeled vehicle and more particularly to a wheel assembly of said vehicle.
BACKGROUND OF INVENTION
[0002] Generally, a two-wheeled vehicle comprises of a frame assembly acting as a skeleton to provide support. In furtherance to it, the vehicle comprises of a front wheel and rear wheel disposed on the front portion and rear portion of the frame assembly respectively. The front wheel is connected to the frame assembly through front suspensions, whereas the rear wheel is connected to the rear portion through rear suspensions. Typically, the front wheel and rear wheel move along to provide motion to the vehicle, wherein the rider riding the vehicle has to balance it on the two wheels. Moreover, some of the riders driving the vehicle find it hard to balance it on two wheels and face a risk of falling while driving.
[0003] Typically, it is very difficult to balance the vehicle at slow speeds (<4-10 Km/h). There are some existing two-wheeled vehicles which are modified considering the usage for specially-abled people, wherein said vehicle comprises of two wheels on the rear making it easy to balance at low speeds. However, maneuvering of such vehicles at higher speeds is difficult. In furtherance to it, there also exists vehicles, which look like two wheelers, but have two wheels on the rear mounted on different hubs. In such cases, where the two wheels are on different hubs; track width (distance between two wheels) between the two wheels is very high. These types of vehicles compromise with standard two-wheeled vehicle dynamics in order to provide standing stability to it. This results in comprising with cornering and maneuvering which a standard two-wheeled vehicle can easily achieve even in traffic condition. Thus, the additional wheels at rear described above would suppress ease of maneuvering provided to the rider.
[0004] Hence, it is desired to have a vehicle comprising a degree of self-balancing feature along with the freedom to maneuver on turns and during banking which a standard tow-wheeled vehicle possesses.
BRIEF DESCRIPTION OF DRAWINGS
[0005] Figure 1 illustrates a side view of an exemplary vehicle in accordance with an embodiment of the present subject matter.
[0006] Figure 2 illustrates an exploded view of a first component and second component in accordance with an embodiment of the present subject matter.
[0007] Figure 3 illustrates a study of balancing moment due to current wheel assembly’s normal reaction with respect to disturbing moment due to centre of gravity offset of said vehicle.
[0008] Figure 4 illustrates a study of balancing moment due to current wheel assembly’s normal reaction with respect to disturbing moment due to centre of gravity offset of said vehicle.
[0009] Figure 5 illustrates a rear view of the exemplary vehicle as shown in Fig. 1, in accordance with an embodiment of the present subject matter.
[00010] Figure 6 illustrates a line diagram to illustrate the variation of pre-determined distance (G) between tires of the wheel assembly with respect to the location of centre of mass of the vehicle.
DETAILED DESCRIPTION
[00011] Typically, a two-wheeled vehicle comprises of a frame assembly extending rearwardly along a vehicle length direction to provide a support the vehicle. The frame assembly acts as a skeleton and a structural member for the vehicle and supports its loads. A front wheel is connected to a front portion of the frame assembly through one or more front suspension(s). The frame assembly extends towards a rear portion of the vehicle. A rear wheel is connected to a rear portion of the frame assembly through one or more rear suspension(s). The rear and front wheel which are provided enable the movement of the vehicle. However, it is balancing the vehicle on two wheels which some of the riders find it difficult, especially beginners & low speed driving.
[00012] Generally, balancing a two-wheeled vehicle is tough, especially for specially-abled people. Thus, to provide a solution for problems as such, two rear wheels are disposed at the end. Such kinds of vehicles provide an easy balance, but the essence, fun and feel of driving a two-wheeled is lost. Such vehicles are hard to maneuver and turn at corners. The whole vehicle is stable at low speeds but while driving at a high speed it gets very unstable and the driving experiences becomes like that of driving a three-wheeled vehicle. Furthermore, in one of the other known arts there are vehicles in which the rear wheel comprises of two wheels, but gives an impression of being one single wheel. In vehicles as such the wheels are mounted on two different hubs. Thus, for such vehicles the track width between the rear wheels is high. However, in vehicles as such standard two-wheeled vehicle dynamics is not taken care and the feel of riding a two-wheeled vehicle is not present. For example, the maneuvering and cornering which the rider can achieve with a two-wheeled vehicle would not be present in vehicles as such. Additionally, having separate hub leads to high cost, more number of parts & complex structure.
[00013] Therefore, an objective of the present subject matter is to provide a vehicle which can be self balanced. In furtherance to it, the present subject matter provides a self balanced vehicle which maintains the standard two-wheeled vehicle dynamics and is easy to maneuver and turn at corners like a standard two-wheeled vehicle. According to one aspect of the present subject matter, a wheel assembly disposed at one end comprising of at least two tires is provided, wherein said tires are mounted on a single hub. According to an additional aspect the two tires of the wheel assembly are separated by a pre-determined gap G.
[00014] In an embodiment, a standard two-wheeled vehicle comprises of a frame assembly providing a support to the whole vehicle. The frame assembly comprises of a head tube disposed in a front portion of the vehicle, wherein a mainframe assembly extends in a downward and rearwardly fashion from the head tube. A rear frame comprising of side tubes is attached to the end portion of the mainframe assembly, wherein the side tubes extend in a rearwardly and upward direction. The vehicle is provided with a wheel assembly, wherein the wheel assembly comprises of two tires and is disposed at one end of the vehicle. As per the present subject matter, the wheel assembly can be provided as a front wheel assembly located a front end and also as a rear wheel assembly located at a rear end of the vehicle. The front wheel assembly is attached to a front suspension(s) and the rear wheel assembly is connected to the side tubes through rear suspension(s) provided therein.
[00015] In an embodiment, the present subject matter discloses a vehicle with a degree of self-balancing feature along with the freedom to maneuver the vehicle on turns and during banking. To achieve the degree of self-balancing feature along with the freedom to maneuver on turns and in traffic; the present invention describes a vehicle with a wheel assembly comprising of two tires mounted on a single hub separated by a pre-determined gap (G). According to one embodiment of the present invention, the distance between the two tires mounted on single hub is maintained in such a way that the disturbing moment due to centre of gravity offset of the vehicle is nullified by the balancing moment of the wheel’s normal reaction. The rider while riding a vehicle tends to move sideways along a certain amount of degree. Such movement of the rider disturbs the centre of gravity of the vehicle and results in difficulty to balance the vehicle. However, the present subject matter nullifies the disturbance and its effects by providing a balance moment. In an embodiment, that balance moment is provided by the present subject matter by using wheel assembly with two tires mounted on one single hub and separated by a pre-determined gap (G). The pre-determined gap (G) is calculated and kept constant within a range of 80mm to 150mm so that the required balance moment is produced.
[00016] In an embodiment, mounting of two tires on a single hub is further implemented by fastening them through suitable fasteners and accommodating a plurality of spacer between them. Furthermore, the present subject matter comprises of two components around which the tires are enveloped. Thus, two tires enveloped around first and second components are mounted on one single hub. Hence through such an assembly the present subject matter provides a balance moment even after the disturbing moment due to centre of gravity offset caused when the rider shifts sideways at a certain degree in a running condition of the vehicle.
[00017] Hence, the present invention here comprises of a wheel assembly comprising of two tires mounted on one single hub and spaced apart by a pre determined distance (G). The present subject matter enables an easy maneuvering and cornering of the vehicle despite of being a self balancing vehicle comprising of two rear wheels. According to an aspect of the present invention the gap (G) between the two tires is optimized such that vehicle will be able to balance in 1G off stand condition. 1G off stand condition refers to vehicle standing vertical on a plane ground without use of any centre stand or side stand. Furthermore, the present invention allows vehicle to balance even with the rider sitting on the vehicle in the vehicle off stand condition and at low speed running condition in slow moving traffic as well.
[00018] The aforesaid and other advantages of the present subject matter would be described in greater detail in conjunction with the figures in the following description.
[00019] Arrows provided in the top right corner of each figure depicts direction with respect to the vehicle, wherein an arrow F denotes front direction, an arrow R indicated R direction, an arrow Up denotes upward direction, an arrow Dw denoted downward direction, an arrow Rh denotes right side, an arrow Lh denoted left side, as and where applicable.
[00020] Figure 1 illustrates a side view of an exemplary vehicle (10), in accordance with an embodiment of present subject matter. The vehicle (10) comprises of a frame assembly (11) which is conventionally an underbone chassis frame which provides a generally open central area to permit “step-through” mounting by a rider. Typically, the frame assembly (11) comprises of a head tube (12), a main tube (13), and a pair of side tubes (14) (only one shown). The head tube (12) is disposed towards the front portion, wherein the main tube (13) extends downwardly and rearwardly from the head tube (12) forming a flat horizontal step-through portion (15). The other end of the main tube (13) is connected with the pair of side-tubes (14) through a bracket (not shown).
[00021] The head tube (12) is configured to rotatably support a steering tube (16) and further connected to the front suspension system (not shown) at the lower end. A handlebar support member (not shown) is connected to an upper end of the steering tube and supports a handlebar assembly (17). The upper portion of a front wheel assembly (18) is covered by a front fender (19) mounted to the lower portion of the steering tube (16). The pair of side-tubes (14) extends from the other end of the main tube (13) and are disposed parallel on either side of the vehicle width direction. Each of the said side tube (14) includes a down frame section (14a) inclined and extending from the main tube (13) and gradually after a certain length extending rearward in a substantially horizontal direction to the rear of the vehicle. A plurality of cross pipes (not shown) is secured in between the pair of side-tubes (14) at selected intervals to support vehicular attachments including a utility box (not shown), a seat assembly (19) and a fuel tank assembly (not shown).
[00022] The seat (19) is supported on the pair of side-tubes (14) on which a rider may sit. Generally, the utility box (not shown) is supported between the front portions of the left and right end of the pair of side-tubes (14) so as to be disposed below the seat (14). A fuel tank assembly (not shown) is disposed on between the rear portions of the pair of the side-tubes (14). The exhaust emission system (9) can be seen disposed at the side extending rearward coupled to the frame assembly. There is front brake (not shown) and rear brake (8) arranged on the front wheel (18) and a rear wheel assembly (7) respectively. The rear wheel assembly (7) is covered by a rear fender (6) with a tail light (5) disposed above it and a support bar (4) place above it at the end of the seat assembly (19). The rear wheel assembly (7) is supported towards the rear side of the frame and functionally coupled to an internal combustion (IC) engine (3) which is horizontally coupled swingably to the rear of the frame assembly. An air cooling system (2) is provided for the IC engine (3) which helps in cooling the assembly because of the excess heat generated within it. The IC engine (3) transfers the drive directly to the rear wheel assembly (7). As per the present subject matter, the vehicle comprises of a wheel assembly (7, 18) located either at the front end acting as a front wheel assembly (18) or at a rear end acting as the rear wheel assembly (7). Furthermore, the wheel assembly (7) comprises of two tires, namely a first tire (as shown in Fig. 5) and a second tire (as shown in Fig. 5). The two tired are enveloped around two components, a first component (shown in Fig. 2) and a second component (shown in Fig, 2). However, for the purposes of this invention and description the wheel assembly (7, 18) is supposedly located at the rear end of the vehicle (10) acting as a rear wheel assembly (7). Thus, henceforth the wheel assembly (7, 18) would be referred as rear wheel assembly (7) just for the purpose of this application.
[00023] Figure 2 illustrates an exploded view of the first component (20) and second component (20’) of the rear wheel assembly (7) in accordance with an embodiment of the present subject matter. In an embodiment, the first component (20) comprises of first rim (21) and second rim (22). In an embodiment, the first component (20) consists of a series of mounting brackets (25) formed around its inner periphery, where the mounting brackets (25) comprises of at least one mounting hole (24) formed in each of them. Similarly, the second component (20’) comprises of first rim (21’) and second rim (22’). In an embodiment, the second component (20’) also comprises of a series of mounting brackets (26) formed around its inner periphery, wherein the mounting brackets (26) comprise of at least one mounting hole (24’) formed in each of them. The first component (20) and second component (20’) are detachably attached to each other through a set of fasteners (27). The set of fasteners (27) are inserted to pass through the mounting holes (24) of the first component (20) and mounting holes (24’) of the second component (20’). Thus, the series of fasteners (27) keep the first component (20) and second component (20’) intact and attached.
[00024] Figure 3 and Figure 4 illustrate a lower limit and an upper limit value respectively for a range of distance between the two tires of the rear wheel assembly (7) when compared to moment about longitudinal axis. According to one embodiment of the present invention the variables M (total mass of the vehicle including rider and both the rear wheels), ? (total mass M rotation due to rider shift), hg (vehicle CG Height including rider with respect to ground), Yg (initial CG offset of the vehicle), Kvt (vertical stiffness of the tire) and ?R (load transfer due to rider shift) is varied throughout the span of the permissible ranges for a standard two-wheeled vehicle. Based on the above study a pre-determined gap (G) to be fixed between the first tire (shown in Fig. 5) and second tire (shown in Fig. 5) is obtained. Thus, the range in which the balancing moment can be achieved after disturbing moment due to CG (centre of gravity) effect is obtained.
[00025] Figure 5 illustrate a rear view of the exemplary vehicle (10) as shown in Fig. 1, in accordance with an embodiment of the present subject matter. In an embodiment, the rear wheel assembly (7) comprises of first tire (51) enveloped on first component (20) and second tire (52) enveloped over second component (20’). In an embodiment, the first tire (51) aligned on a first plane (53) parallel to a vehicle’s vertical central plane (54) (also the central longitudinal axis), wherein said first plane (53) vertically passes through centre of said first tire (51). In an embodiment, the second tire (52) is aligned on a second plane (55) parallel to said vehicle’s vertical central plane (54), wherein said second plane (55) vertically passes through centre of said second tire (52). In an embodiment, the first tire (51) and second tire (52) are mounted on a same single hub (56). As per the present subject matter, a pre-determined gap “G” is maintained between the first plane (53) passing through the first tire (51) and said second plane (55) passing through the second tire (52), wherein the value of pre-determined gap ‘G’ lies in a range of 80mm to 150mm. Thus, based calculations & simulation plots the pre-determined gap ‘G’ enables a balancing moment even after the disturbing moment caused due to CG (centre of gravity) offset triggered after the rider’s shifting. However, the pre determined gap ‘G’ allows the vehicle to have the maneuvering and cornering which a standard two-wheeled vehicle has.
[00026] Figure 6 shows a line diagram to illustrate the variation of pre determined distance (G) between the first tire (51) and second tire (52) of the rear wheel assembly (7) with respect to the location of centre of mass of the vehicle. For such a vehicle:
M = Total mass of the vehicle including rider and both the rear wheels.
? = Total mass M rotation due to rider shift.
hg = Vehicle CG Height including rider with respect to ground.
Yg = Initial CG offset of the vehicle.
d = Distance between both the wheel.
?R =Load transfer due to rider shift.
Compression of the tire on RHS or Extension of the tire on LHS:
x = ? * d/2.
Load transfer from one tire to another:
?R = (? * d/2)*.
Normal moment applied by wheel due to the load transfer:
= ?R * d.
= (? * d/2)* * d. ------------------------------------ (1)
Mass M shift due to rotation ?:
Y = Yg*cos (?) + hg*sin (?)
Y = Yg + hg*?. (Since ? is very small)
Disturbing moment due to mass M rotation:
= Y * M = M (Yg + hg*?) ……………………………………………. (2)
Normal balancing moment applied by the wheel should be more than the disturbing
moment due to rider shift. Hence Equation (1) should be greater than (2).
? * d/2)* * d > M (Yg + hg * ?)
[00027] Hence, the distance between the wheels is a function of the mass M of the vehicle, height of the centre of gravity hg, initial offset of the centre of gravity of the vehicle, a small deviation ? (tolerance limit of the vehicle for tilting) of the vehicle.
[00028] Hence, in the present subject matter it is the distance between the first tire (51) and second tire (52) is being varied. As per the present subject matter, the lowest value for the pre-determined gap (G) between said first plane (53) passing through the first tire (51) and second plane (55) passing through the second tire (52) is obtained as 80mm. Further, highest value for the pre-determined gap (G) between said first plane (53) passing through the first tire (51) and the second plane (55) passing through the second tire (52) is obtained as 150mm. Hence, the pre-determined gap “G” between the first plane (53) passing through the first tire (51) and the second plane (55) passing through the second tire (52) for providing a self-balancing feature to the vehicle lies in a range between 80mm to 150mm.
[00029] Thus, the present subject matter provides a rear wheel assembly (7) comprising of a first tire (51) and a second tire (52), wherein a pre-determined gap ‘G’ is maintained between the first tire (51) and second tire (52). Hence, the vehicle (10) as per the present subject matter is balanced vertically for a small angle of deviation from vertical even at low speeds. This is achieved due to the moment of centre of gravity about the central longitudinal axis being balanced by the balance moment applied by rear wheel assembly (7) due to the load transfer.
[00030] It is to be understood that the aspects of the embodiments are not necessarily limited to the features described herein. Many modifications and variations of the present subject matter are possible in the light of above disclosure. Therefore, within the scope of claims of the present subject matter, the present disclosure may be practiced other than as specifically described.
,CLAIMS:We Claim:
1. A wheel assembly (7, 18) for a single hub (56) of a vehicle (10), wherein said wheel assembly (7, 18) comprises:
a first tire (51) aligned on a first plane (53) parallel to a vehicle’s vertical central plane (54), wherein said first plane (53) vertically passes through centre of said first tire (51);
a second tire (52) aligned on a second plane (55) parallel to said vehicle’s vertical central plane (54), wherein said second plane (55) vertically passes through centre of said second tire (52); and
a pre-determined distance ‘G’ maintained between said first plane (53) passing through said first tire (51) and said second plane (55) passing through said second tire (52) is substantially in a range of 80 mm to 150 mm.
2. The wheel assembly (7, 18) for a single hub (56) of a vehicle (10) as claimed in claim 1, wherein said first tire (51) is enveloped around a first component (20).
3. The wheel assembly (7, 18) for a single hub (56) of a vehicle (10) as claimed in claim 1, wherein said second tire (52) is enveloped around a second component (20’).
4. The wheel assembly (7, 18) for a single hub (56) of a vehicle (10) as claimed in claim 2 and claim 3, wherein said first component (20) and said second component (20’) are detachably attached to each other.
5. The wheel assembly (7, 18) for a single hub (56) of a vehicle (10) as claimed in claim 2, wherein said first component (20) comprises of a series of mounting brackets (25) formed around its inner periphery with at least one mounting hole (24) formed therein.
6. The wheel assembly (7, 18) for a single hub (56) of a vehicle (10) as claimed in claim 3, wherein said second component (20’) comprises of a series of mounting brackets (26) formed around its inner periphery with at least one mounting hole (24’) formed therein.
7. The wheel assembly (7, 18) for a single hub (56) of a vehicle (10) as claimed in claim 2 and claim 3, wherein said first component (20) and said second component (20’) are detachably attached to each other by insertion and tightening of a set of fasteners (27) through said mounting holes (24, 24’) formed on said mounting brackets (25, 26).
8. The wheel assembly (7, 18) for a single hub (56) of a vehicle (10) as claimed in claim 2 and claim 3, wherein said first component (20) and said second component (20’) are mounted on said one single hub (56).
9. The wheel assembly (7, 18) for a single hub (56) of a vehicle (10) as claimed in claim 1, wherein said wheel assembly (7, 18) is provided at a front end of said vehicle (10) when seen form a front view of said vehicle (10).
10. The wheel assembly (7, 18) for a single hub (56) of a vehicle (10) as claimed in claim 1, wherein said wheel assembly (7, 18) is provided at a rear end of said vehicle (10) when seen from a front view of said vehicle (10).