Claims:We Claim:
1. A wheel assembly (145) for a vehicle (100), said wheel assembly (145) comprising:
a rim sub-assembly (201’);
a motor unit (135);
said rim sub-assembly (201’) comprising
a rim (201);
an annular holding member (202);, said annular holding member (202) having a base portion (HB), and a projection portion (202a, 202b), said projection portion (202a, 202b) extending orthogonally to said base portion (HB), and said projection portion (202a, 202b) being oriented along a rotation axis AA’ of said rear wheel assembly (145),
wherein said motor unit (135) being detachably attached with said rim sub-assembly (201’).
2. The wheel assembly (145) as claimed in claim 1, wherein said annular holding member (202) being fixedly attached with said rim (201) of said rim sub-assembly ( 201’).
3. The wheel assembly (145) as claimed in claim 1, wherein said motor unit (135) being housed inside a motor casing and said motor casing having a one or more mounting boss (204), wherein said base portion (HB) of said annular holding member (202) being configured with one or more holes (205) for detachably attaching said motor unit (135).
4. The wheel assembly (145) as claimed in claim 3, an outer portion of said one or more mounting boss (204) of said motor unit (135) conforms with a profile of said one or more holes (205) of said annular holding member (202) for detachably attaching said motor unit (135).
5. The wheel assembly (145) as claimed in claim 1 or claim 4, wherein said motor unit (135) being detachably attached with said annular holding member (202) of said rim sub-assembly (201), said attachment being through a one or more attachment means like fasteners (205).
6. The wheel assembly (145) as claimed in 1, wherein said motor unit (135) being centrally and co-axially secured in said rim sub-assembly (201’) along a rotation axis AA’, wherein an outer diameter of said motor unit (135) being adapted to have one of a transition fit and an interference fit with an inner circumferential surface (R4) of said rim (201).
7. The wheel assembly (145) as claimed in claim 1, wherein said rim (201) having a plurality of inner annular circumferential surfaces (R1, R2, R3, R4); said projection portion (202a, 202b) of said annular holding member (2012) having a plurality of an outer annular circumferential surfaces (H1, H2, H3), wherein said annular holding member (202) being fixedly attached to one of an inner diameter side of said rim (201) .
8. The wheel assembly (145) as claimed in claim 1, wherein said inwardly projecting member (201) having one or more cut out profile (207) forming an access portion for accessing an air inlet valve facilitating filling up air in a tyre of said vehicle (100).
9. The wheel assembly (145) as claimed in claim 1, wherein said rim (201) having a plurality of inner annular circumferential surfaces (R1, R2, R3, R4); said projection portion (202a, 202b) of said annular holding member (2012) having a plurality of an outer annular circumferential surfaces (H1, H2, H3), wherein said annular holding member (202) being fixedly attached to a lateral side of said rim (201) and being configured to abut said rim (201) from a lateral side of said rim (201).
10. The wheel assembly (145) as claimed in claim 1, wherein a portion of an outer annular second lateral surface (H2) of said plurality of outer annular circumferential surfaces (H1, H2, H3) of said holding member (202) abuts a portion of a complimenting second inner annular circumferential surface (R2) of said plurality of inner annular circumferential surfaces (R1, R2, R3, R4) of said rim (201) where said second inner annular circumferential surface (R2) of said plurality of inner annular circumferential surfaces (R1, R2, R3, R4) of said rim (201) being parallel to said rotation axis AA’
11. The wheel assembly (145) as claimed in claim 10, wherein an outer annular third circumferential surface (H3) of said annular holding member (202) being adapted to fixedly attach with an inner annular third circumferential surface (R3) of said rim (201).
12. The wheel assembly (145) as claimed in claim 7, wherein said projection portion (202a, 202b) of said annular holding member (202) being a substantially C shape portion; an open end of said C shape facing a lateral side of said rear wheel assembly (145); and wherein said C shaped portion being fixedly attached with said rim (201) of said wheel assembly (145).
13. The wheel assembly (145) as claimed in claim 12, wherein said C shape portion has an upper half projection portion (202a) adapted to act as a reinforcing member enabling structural strength to said rim (201) of said rear wheel assembly.
14. The wheel assembly (145) as claimed in claim 7, wherein said the holding member (202) having an annular outer diameter being more than and innermost diameter of said rim (201), said the holding member (202) having an annular outer diameter being less than an outermost diameter of said rim (201).
15. The wheel assembly (145) as claimed in any of the preceding claims wherein said vehicle (100) being one of an electric vehicle (100) and a hybrid vehicle (100); wherein said hybrid vehicle (100) being configured with an internal combustion engine (125) and an motor unit (135).
, Description:TECHNICAL FIELD
[0001] The present subject matter generally relates to a rear wheel assembly for a vehicle. Particularly but not exclusively relates to a hub mounted motor type rear wheel assembly.
BACKGROUND
[0002] Typically, a motor unit mounted in a hub of a rear wheel assembly powers electric or hybrid vehicles. The hub mounted motor unit directly drives the rear wheel assembly. The motor unit typically comprises a motor accommodated within a motor casing, where the motor casing includes a left case member and a right case member attached to one another. The motor casing comprised of the left case member and the right case member is generally manufactured by a metal casting process.
[0003] Mounting the motor unit to the rear wheel assembly involves welding at least a portion of the motor casing to a rim of the rear wheel assembly. In other words, the motor unit is permanently attached to the rim to transfer a drive troque. Traction to the rear wheel assembly from the motor unit is ensured through the weld formed between the rim and the motor unit. In the absence of the physical connection between the rim and the motor unit, traction to the rear wheel assembly from the motor unit cannot be achieved. Therefore, attachment of the motor unit to the rim is essential.
BRIEF DESCRIPTION OF THE DRAWINGS
[0004] The detailed description described with reference to the accompanying figures. The same numbers have been used throughout the drawings to reference like features and components.
[0005] Fig.1 is a side view of a step through vehicle as per one embodiment of the present invention.
[0006] Fig.2 is an assembled view of rear wheel assembly with motor unit as per one embodiment of the present invention.
[0007] Fig. 2a is an exploded view of rear wheel assembly with motor unit as per one embodiment of the present invention.
[0008] Fig. 3 is a sectional view of rear wheel assembly with motor unit as per one embodiment of the present invention.
[0009] Fig. 3a is a zoom in view of sectional view of wheel assembly with motor unit as per one embodiment of the present invention
DETAILED DESCRIPTION
[00010] Typically, among electric/hybrid vehicle driving devices, a device driving a rear wheel assembly directly, is known as a hub-mounted type motor unit. The motor unit mentioned herein is a driving device provided near the rear wheel assembly of an electric/hybrid vehicle. The motor unit is disposed inside or near the rear wheel assembly and known as wheel hub motor. The motor unit disposed near/inside the rear wheel assembly converts electrical energy into mechanical energy for propulsion of the vehicle.
[00011] However, in another scenario, when the motor unit is disposed anywhere in the vehicle, where the motor transforms the electrical energy into mechanical energy and then transfers it to the rear wheel assembly, this may lead to undesirable transmission losses in the vehicle. This configuration also leads to uneven distribution of CG of the vehicle. Hence, to avoid this type of losses, the motor unit as disposed inside the rear wheel assembly is preferred. The motor unit disposed inside the rear wheel assembly may be categorized into a first type having a speed reduction mechanism and a second type also referred as a direct drive type without a speed reduction mechanism. The motor unit may easily ensure a sufficient rotational force for driving the electric vehicle at the time of starting the vehicle.
[00012] Generally, a tyre is disposed on a rim to form a rear wheel assembly. The rim makes up outer circular design of the rear wheel assembly to accommodate inside edge of the tyre of the rear wheel assembly. The rim of the rear wheel assembly also accommodates the motor unit for propulsion of the vehicle. Typically, the rim of the wheel assembly is made up of sheet metal or aluminum alloy cast. However, in an aluminum alloy cast type rim the motor unit cannot be easily disposed within the wheel due to space constraints and such type results in undesirable interference fit. This type may transfer the impact taken by cast rim to the motor unit, which is not preferred. Therefore, the sheet metal type rim is preferred to disposed the motor unit in the vehicle.
[00013] In a sheet metal type rim, at least a part of the rim is welded to a casing of the motor unit disposed inside the rear wheel assembly, ensuring attachment of the motor unit with the rim of the wheel assembly. However, the rim is typically prone to frequent damage that may occur due to an road impact experienced by the rim. Such loads arise due to low tyre pressure or on coming in contact with road disturbances such as stones/other foreign matter, etc. Since the rim is permanently attached to the motor unit, any damage, like bent rim, to the rim necessitates changing the entire rim along with the motor unit and / or motor housing, which proves to be very cost intensive. Such damage may also affect drivability of the vehicle. The bent rim may lead to shakiness or wobble and also transfer undesirable vibrations to a steering assembly. In addition, this causes the tyre to make uneven contact with surface of road resulting in uneven wear and poor handling performance of the vehicle. Moreover, this also affects ease of serviceability of the rear wheel assembly, because a portion of the motor casing remains attached to the rim and handling the rim itself becomes cumbersome. The degree of freedom associated with designing/modifying the rim also gets affected. For example, the rim cannot be customized or the aesthetic appeal of the rim cannot be changed at a later point of time based on requirements of the customer or need of the manufacturer to offer variety of looks. Customization of the rim would involve changing the motor unit. Similarly, due to the permanent attachment of the motor unit with the rim, the motor unit cannot be upgraded or downgraded based on wheel size, without involving complete changeover of the rear wheel assembly including that of the motor unit all of which is not desirable.
[00014] Therefore, there is a need for providing an improved means of securing the motor unit to the rim of the rear wheel assembly which addresses all problems cited above and other problems of known art while at same time ensuring ease of serviceability of the rim.
[00015] Typically, in known art, a rim of a wheel assembly is integrally attached to a casing of a motor unit through various attachment means like welding. This configuration has its own disadvantage that since the rim is permanently attached to the motor unit, any damage to the rim necessitates changing the tyre rim along with the motor unit, which proves to be very cost intensive. Further, when a rim is bent and it tends to pull away from tyre potentially dislocating the type from the rim, can cause air leaks, which raises safety concern for rider riding the vehicle. Moreover, it affects ease of serviceability of the rear wheel assembly, because a portion of the motor casing remains attached to the rim and handling such a rim itself becomes cumbersome.
[00016] Hence, there exists a challenge of securely mounting a motor unit on to rim of rear wheel assembly while ensuring ease of serviceability of the rim and overcoming all problems of known art.
[00017] Therefore, there is a need to have an improved mounting of motor unit with rim of rear wheel assembly, which overcomes all of the above problems and other problems known in art.
[00018] The present subject matter discloses an improved means of securing motor unit with a rim of a rear wheel assembly while ensuring ease of serviceability of the rim of the wheel assembly.
[00019] As per one aspect of present invention, a vehicle comprises of a frame assembly, a steering assembly, a wheel assembly, a transmission system. Further, as per one aspect of the present invention, a fuel tank assembly is mounted on a main frame with various attachment means, for example, fasteners.
[00020] As per one aspect of the present invention, a rear wheel assembly includes a rim having an innermost diameter and an outermost diameter, an annular holding member having a base portion and a projection portion, the projection portion extending orthogonally to the base portion and the projection portion being along an axial direction of the annular holding member. As per an embodiment, the annular holding member has a substantially arc shaped cross section profile. As per one embodiment of the present invention, the annular holding member is fixedly attached to one side of the rim with various attachment means like welding and forms a part of the rim. Aa per an alternate embodiment, the holding member is co-axially attached with the rim and configured to abut the rim from a lateral side of the rim such that at least a portion of a second lateral surface of the holding member abuts a complimenting lateral second annular circumferential surface of the rim. As per another aspect of the alternate embodiment, the third outermost circumferential surface of the annular holding member is adapted to attach with a third annular circumferential portion of the rim with an interference fit at the attachment region. As per an aspect of the present invention, the holding member has an annular outer diameter more than the innermost diameter of the rim but less than the outermost diameter of the rim. The third outer most circumferential surface of the holding member is adapted to engage in a press fit configuration with one of a receiving annular circumferential portion of the rim which is the third annular circumferential surface of the rim. The base portion of the holding member is provided with plurality of holes for enabling attachment means like fasteners to be assembled through the holes. A power unit, for example, a motor unit is dispsoed at the inner circumference region of the rim. As per an aspect of the present invention, the motor unit is abuttingly and detachably attached at one of the side portion of said motor unit with the base portion of the holding member with the various attachment means like fasteners. This configuration ensures ease of serviceability of the rim when required, without replacing the motor unit along with rim of the vehicle.
[00021] As per one aspect of the present invention, the holding member includes one or more air inlet valve accessing portions, to facilitate accessing of the air inlet valve for filling up and inspecting air pressure in a tyre of the wheel assembly.
[00022] Various other features and advantages of the invention are described in detail below with reference to an embodiment of a two wheeled straddle type vehicle along with the accompanying drawings. In the drawings, like reference numbers generally indicate identical, functionally similar, and/or structurally similar elements.
[00023] Fig. 1 a left side view of a step through vehicle (“the vehicle”) 100, in accordance with an embodiment of the present subject matter. The vehicle (100) illustrated, has a frame assembly (105) shown schematically by dotted lines. The frame assembly (105) includes a head tube (105H), a frame sub-assembly (105b). One or more suspensions (110) connect a front wheel (115) to a handlebar assembly (120), which forms the steering assembly of the vehicle (100). The steering assembly is rotatably disposed through the head tube (105H). The main frame assembly (105B) extends rearwardly downward from the head tube (105H) and includes a bent portion (105M) thereafter extending substantially in a longitudinal rearward direction. Further, the frame assembly (105) includes one or more rear frame member (105C) extending inclinedly rearward from a rear portion of the main frame assembly (105B) towards a rear portion of the vehicle (100).
[00024] The vehicle (100) includes a power unit, for example, a motor unit (135) and an internal combustion engine (125). The motor unit is coupled to a rear wheel assembly (145) and is known as wheel hub motor unit. In one embodiment, the IC engine (125) is swingably connected to the frame assembly (105). In the present embodiment, the IC engine (125) is mounted to the swing arm (140) and the swing arm (140) is swingably connected to the frame assembly (105). Further, the vehicle (100) includes a transmission means (130) coupling the rear wheel (145) to the power unit. The transmission means (130) includes a continuously variable transmission, an automatic transmission, or a fixed ratio transmission. A seat assembly (150) is disposed above the power unit and is supported by the rear frame member (105C) of the frame assembly (105). In the present embodiment, the seat assembly (150) is hingedly openable. The frame assembly (105) defines a step-through portion ahead of the seat assembly (150). A floorboard (155) is disposed at the step-through portion, wherein a rider can operate the vehicle (100) in a seated position by resting feet on the floorboard (155). Further, the floorboard (155) is capable of carrying loads.
[00025] The vehicle includes an on-board battery (not shown) that drives the motor unit (135). Further, the frame assembly (105) is covered by plurality of body panels including a front panel (160A), a leg shield (160B), an under-seat cover (160C), and a left and a right side panel (160D), all panels being mounted on the frame assembly (105) and covering the frame assembly (105) and parts mounted thereof.
[00026] In addition, a front fender (165) is covering at least a portion of the front wheel (115). In the present embodiment, the front fender (165) is integrated with the front panel (160A). A utility box (not shown) is disposed below the seat assembly (150) and is supported by the frame assembly (105). A fuel tank (not shown) is disposed adjacently to the utility box (not shown). A rear fender (175) is covering at least a portion of the rear wheel assembly (145) and is positioned below a fuel tank and upwardly of the rear wheel assembly (145). One or more suspension(s) (180) are provided in the rear portion of the vehicle (100) for connecting the swing arm (140) and the rear wheel assembly (145) to the frame assembly (105) for damping the undesirable forces from the wheel (145) and the power unit from reaching the frame assembly (105).
[00027] Furthermore, the vehicle (100) comprises of plurality of electrical and electronic components including a headlight (185A), a tail light (185B), a transistor controlled ignition (TCI) unit (not shown), an alternator (not shown), a starter motor (not shown). Further, the vehicle 100 includes one or more of an anti-lock braking system (ABS), a synchronous braking system (SBS), and a vehicle control system (VCS)
[00028] Fig. 2 is an assembled view of rear wheel assembly (145) along with the motor unit (135) and Fig. 2a is an exploded view of rear wheel assembly (145) with motor unit (135) as per one embodiment of the present invention. As per one embodiment of the present invention, the wheel assembly (145) includes a rim (201), a tyre (not shown) and an annular holding member (202). The rim (201) has a skeletal outer edge that holds the tyre wrapped around it. As per an embodiment, the rim (201) includes a plurality of inner annular circumferential surfaces (R1, R2, R3, R4) disposed on an inner diameter side of the rim (201) (shown in Fig 3a) As per one embodiment of the present invention, the motor unit (135) is coupled with the rim (201) such that at least one or more shaft (203a, 203b) of the motor unit (135) is projected laterally outwardly in left and right side of the vehicle and is mounted to the swing arm (140). The motor unit (135) is attached with the rim (201) of the wheel assembly (145) such that the motor unit (135) forms part of the rear wheel assembly (145) (as shown in fig. 1) and act as a rear wheel unit. The rear wheel assembly (145) has a rotation axis AA’ passing centrally around which the rear wheel assembly (145) rotates during motion of the vehicle (100). In an assembled condition of said rear wheel assembly (145), the rotation axis AA’ is oriented in a lateral direction of vehicle and is oriented parallel to the ground. The motor unit (135) is disposed co-axially along axis AA’ thereby maintaining desirable lateral CG of the vehicle. As per one aspect of the present invention, the annular holding member (202) has a base portion with a mounting surface (HB) (shown in Fig 3a) and a projection portion (202a, 202b) the projection portion (202a, 202b) extending orthogonally to the base portion (HB) and the projection portion (202a, 202b) being oriented along the axial direction AA’ of the rear wheel assembly (145). As per another aspect of the present invention, the projection portion (202a, 202b) includes a plurality of outer annular circumferential surfaces (H1, H2, H3) (shown in Fig 3a) on an outer diameter side. As per another aspect of the present invention, the annular holding member (202) and is fixedly attached to an inner diameter side of the rim (201) with various attachment means like welding and forms a part of the rim. In another aspect, the holding member (202) attached with a lateral side of the rim (201) and configured to abut the rim (201) from a lateral side of the rim (201) such that at least a portion of an outer annular second lateral surface (H2) of said plurality of outer annular circumferential surfaces (H1, H2, H3) of the holding member (202) abuts a portion of a complimenting second inner annular circumferential surface (R2) of said plurality of inner annular circumferential surfaces (R1, R2, R3, R4) of the rim (201) where the inner annular second circumferential surface (R2) of said plurality of inner annular circumferential surfaces (R1, R2, R3, R4) of the rim (201) is parallel to the rotation axis AA’. As per the alternate embodiment, the outer annular third circumferential surface (H3) of the annular holding member (202) is adapted to attach with an inner annular third circumferential surface (R3) of the rim (201) with an interference fit at the attachment region ensuring reduced mass of rear wheel assembly (145). As per an additional embodiment, the annular holding member (202) is fixedly attached to the rim (201). The base portion (HB) of the annular holding member (202) includes at least one or more holes (205) for receiving at least one or more fasteners (206). As per one embodiment of the present invention, the motor unit is detachably attached to the annular holding member (202), where the annular holding member (202) forms part of the rim (201), the attachment being through various attachment means like at least one or more fasteners (206). The motor unit (135) is housed inside a motor casing. The motor casing includes at least one or more mounting boss (204) to enable mounting of said motor unit (135) to the annular holding member (202). As per an embodiment, an outer portion of the mounting boss (204) conforms with profile of at least one or more holes of the annular holding member (202) and where the motor unit is detachably attached using one or more fasteners. As per an additional aspect of the present invention, the motor unit (135) is secured inside the rim (201) where an outer diameter surface of the motor unit (135) being adapted to have one of a transition fit and an interference fit with a fourth annular circumferential surface (R4) of said plurality of inner annular circumferential surfaces (R1, R2, R3, R4) of the rim (201) thereby providing rigid and co-axial attachment of the motor unit (135) with the rim (201) and the annular holding member (202). As per an embodiment, the assembly of the rim (201) and the annular holding member (202) forms a rim sub-assembly (201’). When the rim (201) suffers damage because of some external factors, the present configuration eliminates requirement of replacement of the motor and thereby protects the motor unit (135) from any undesirable damage, , thereby being cost effective. This configuration ensures that at time of serviceability of the rim (201), the motor unit (135) can be easily detached from the rim sub-assembly (201’) of the wheel assembly (145), thereby ensuring ease of serviceability of the rim (201) of the rear wheel assembly (145). This configuration also ensures ease of assembly of the motor unit (135) with the rim sub-assembly (201’) of the wheel assembly (145).
[00029] As per one embodiment of the present invention, the annular holding member (202) is provided with a one or more cutout profile (207) which acts as an air inlet valve accessing portion, to facilitate accessing of an air inlet valve (not shown) of the wheel assembly, for filling up air.
[00030] Fig. 3 is a sectional view of rear wheel assembly with motor unit and Fig. 3a is a zoom in view of sectional view of wheel assembly with motor unit as per one embodiment of the present invention. As per one embodiment of the present invention, the annular holding member (202) is fixedly attached to the rim (201) of the rear wheel assembly (145). More precisely, the projection portion (202a, 202b) of the annular holding member (202) is as a substantially C shaped portion, where the open end of the C shape faces a lateral external side of the rear wheel assembly (145) and the C shaped portion is fixedly attached with the rim (201) of the wheel assembly (145). Further, the C shaped portion has an upper half projection portion (202a) which act as a reinforcing member, ensuring structural strength to the rim (201) of the rear wheel assembly (145). The C shape so formed enables desirable compliance (reduced stiffness) of the rim sub-assembly (201’) thereby enabling absorbing sharp loads and shocks from being transferred to the critical motor unit (135) and providing a fail-safe rear wheel assembly (145). This configuration also significantly reduces possibility of permanent deformation/bending of the rim sub-assembly (201’) of the rear wheel assembly (145).
[00031] The embodiment explained in Fig. 2 of the present invention helps in securing the motor unit to the rim of the wheel assembly while ensuring ease of accessibility and serviceability of the rim as well as overcoming all the problems known in the art.
[00032] Advantageously, the embodiments of the present invention, describes the potential modifications in the securing the motor unit with the rim disposed in the vehicle
[00033] Many other improvements and modifications may be incorporated herein without deviating from the scope of the invention.

 
List of reference symbol:
Fig. 1:
100: Vehicle
185A: headlight
160A: front panel
105: frame assembly
105A: Head Tube
165: Front Fender
110: Front Suspensions
115: Front Wheel
160B: Leg Shield
155: Floorboard
105B: frame sub-assembly
160C: Under Seat Cover
125: IC Engine
130: Transmission Means
140: Swing Arm
145: Rear Wheel assembly
135: Motor unit
180: Rear Suspension
175: Rear Fender
185B: Tail Light
160D: right side panel
105c: Rear Tubes
150: Seat Assembly
Fig. 2:
203a, 203b: Shafts
202: annular holding Member
201: Rim
Fig. 2a:
204: mounting boss
201a: Inner Diameter side of rim
207: Cut out profile
205: Mounting hole
206: Fasteners
Fig. 3a
202a, 202b: Projection portion
HB – Mounting surface
201’- Rim sub-assembly
H1, H2, H3 – Outer annular circumferential surfaces
R1, R2, R3, R4 – Inner annular circumferential surfaces