Description:ECHNICAL FIELD
[0001] The present subject matter generally relates to an electric motor for a vehicle. More specifically, the present subject matter provides an improved, light weight and compact rotor assembly for the electric motor.
BACKGROUND 5
[0002] Electric vehicles, such as two-wheeler vehicles, have a hub motor that includes a rotor assembly and a stator assembly. The rotor assembly, nestled within the stator assembly, plays a vital role in generating the torque that drives the hub motor. The stator assembly is stationary part of the motor, and the rotor assembly is the rotating part of the motor. Major parts of such a 10 rotor assembly include a rotor rim, rotor ring, plurality of magnets etc. Permanent magnets are arranged in a specific pattern depending on the motor design (e.g., cylindrical, segmented) on the rotor ring, defining a rotor core. The shape of the rotor core varies depending on magnet arrangement and design, often resembling a disc or cylinder with slots or holes. 15
[0003] Conventional designs of rotor assembly provide various challenges pertaining to weight, magnet placement, and manufacturing complexity. Typically used materials of the components of the rotor assembly significantly contribute to the overall weight that hinders motor lightness. Increased weight reduces efficiency, range, and performance, especially in lightweight vehicles. 20 Another drawback of existing designs of rotor assembly poses a problem of placing magnets precisely on the rotor ring at desired locations to maintain
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desired gap between the adjacent magnets, which is a complex process and requires high precision machines to place the magnets accurately. The use of high precision machines also increases the overall cost of manufacturing. Inaccurate magnet placement can negatively affect motor performance, torque, and efficiency. Traditional methods like welding and manual magnet placement 5 is an extremely time-consuming process and increase the overall manufacturing time and cost. In addition, long manufacturing time and high manufacturing costs hinder the affordability and scalability of the hub motors. [0004] Thus, there arises a need for an improved rotor assembly for a hub motor, which can overcome above mentioned disadvantages.
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[0005] Further limitations and disadvantages of conventional and traditional approaches will become apparent to one of skill in the art, through comparison of described systems with some aspects of the present disclosure, as set forth in the remainder of the present application and with reference to the drawings. 15
SUMMARY
[0006] The following summary is illustrative only and is not intended to be in any way limiting. In addition to the illustrative aspects, embodiments, and features described above, further aspects, embodiments, and features will become apparent by reference to the drawings and the following detailed 20 description.
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[0007] According to embodiments illustrated herein, the present disclosure provides a rotor assembly for an electric motor. The rotor assembly comprises a rotor rim, a rotor ring coupled to the rotor rim and a separator coupled to the rotor ring. The separator comprises a plurality of slots to accommodate plurality of magnetic elements.
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[0008] In an embodiment, the rotor rim is made up of a first material and the rotor ring is made up of a second material. In an embodiment, the first material is steel, and the second material is medium carbon steel.
[0009] In an embodiment, the rotor ring comprises one or more first grooves arranged circumferentially. 10
[00010] In an embodiment, the rotor rim and the rotor ring are arranged such that at least one gap is provided between a side portion of the rotor ring and a side portion of the rotor rim.
[00011] In an embodiment, the one or more first grooves are provided on the rotor ring such that the one or more first grooves are facing the gap formed 15 between the rotor rim and the rotor ring.
[00012] In an embodiment, the rotor ring comprises a plurality of second grooves that are configured spaced apart.
[00013] In an embodiment, the separator comprises at least one ring shaped member and a plurality of protrusions with a gap therebetween to form the one 20 or more slots.
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[00014] In an embodiment, the plurality of slots is either open slots which are open from one side, or closed slots which are closed from opposite sides.
[00015] According to embodiments illustrated herein, the present disclosure also provides a vehicle, such as but not limited to a two-wheeled vehicle, comprising an electric motor. The electric motor comprises a stator assembly 5 and a rotor assembly. The rotor assembly comprises a rotor rim, a rotor ring coupled to the rotor rim and a separator coupled to the rotor ring. The separator comprises a plurality of slots to accommodate plurality of magnetic elements.
[00016] In an embodiment, the electric motor is a hub motor configured with a rear wheel or front wheel of the vehicle. 10
BRIEF DESCRIPTION OF DRAWINGS
[00017] The present invention will become more fully understood from the detailed description given herein below and the accompanying drawings which are given by way of illustration only, and thus are not limitative of the present 15 invention.
[0001] The detailed description is described with reference to the accompanying figures, which is related to a rotor assembly for a motor in a vehicle which can be a two-wheeled vehicle being one embodiment of the present subject matter. However, the present subject matter is not limited to the 20 depicted embodiment(s). In the figures, the same or similar numbers are used throughout to reference features and components.
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[0002] Fig. 1 illustrates a perspective view of a rotor assembly, in accordance with an embodiment of the present subject matter.
[0003] Fig. 2 illustrates an exploded view of the rotor assembly, in accordance with an embodiment of the present subject matter.
[0004] Fig. 3 illustrates a perspective view of a rotor ring, in accordance 5 with an embodiment of the present subject matter.
[0005] Fig. 4 illustrates a perspective view of a separator having open slots, in accordance with an embodiment of the present subject matter.
[0006] Fig. 5 illustrates a perspective view of the separator of the rotor assembly having closed slots, in accordance with another embodiment of the 10 present subject matter.
[0007] Fig. 6 illustrates a perspective view of the rotor ring of the rotor assembly, in accordance with another embodiment of the present subject matter.
[0008] Fig. 7 illustrates a top view of the rotor assembly, in accordance with an embodiment of the present subject matter. 15
[0009] Fig. 8 illustrates a sectional view of the rotor assembly, in accordance with an embodiment of the present subject matter.
[00010] Fig. 9 illustrates a perspective view of a vehicle having the rotor assembly, in accordance with an embodiment of the present subject matter.
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DETAILED DESCRIPTION
[00011] The present disclosure may be best understood with reference to the detailed figures and description set forth herein. Various embodiments are discussed below with reference to the figures. However, those skilled in the art will readily appreciate that the detailed descriptions given herein with respect 5 to the figures are simply for explanatory purposes as the subject matter may extend beyond the described embodiments. For example, the teachings presented, and the needs of a particular application may yield multiple alternative and suitable approaches to implement the functionality of any detail described herein. Therefore, any approach may extend beyond the particular 10 implementation choices in the following embodiments described and shown.
[00012] Exemplary embodiments are described with reference to the accompanying drawings. Wherever convenient, the same reference numbers are used throughout the drawings to refer to the same or like parts. While examples and features of disclosed principles are described herein, modifications, 15 adaptations, and other implementations are possible without departing from the spirit and scope of the disclosed embodiments. It is intended that the following detailed description be considered as exemplary only, with the true scope and spirit being indicated by the following claims.
[00013] References to “one embodiment,” “at least one embodiment,” “an 20 embodiment,” “one example,” “an example,” “for example,” and so on indicate that the embodiment(s) or example(s) may include a particular feature, structure, characteristic, property, element, or limitation but that not every
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embodiment or example necessarily includes that particular feature, structure, characteristic, property, element, or limitation. Further, repeated use of the phrase “in an embodiment” does not necessarily refer to the same embodiment. [00014] The present invention now will be described more fully hereinafter with different embodiments. This invention may, however, be embodied in 5 many different forms and should not be construed as limited to the embodiments set forth herein; rather those embodiments are provided so that this disclosure will be thorough and complete, and fully convey the scope of the invention to those skilled in the art.
[00015] The present subject matter is further described with reference to 10 accompanying figures. It should be noted that the description and figures merely illustrate principles of the present subject matter. Various arrangements may be devised that, although not explicitly described or shown herein, encompass the principles of the present subject matter. Moreover, all statements herein reciting principles, aspects, and examples of the present subject matter, as well as 15 specific examples thereof, are intended to encompass equivalents thereof.
[00016] Various features and embodiments of the present subject matter here will be discernible from the following further description thereof, set out hereunder. It is contemplated that the concepts of the present subject matter may be applied to any kind of vehicle within the spirit and scope of this subject 20 matter. The detailed explanation of the constitution of parts other than the present subject matter which constitutes an essential part has been omitted at suitable places.
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[00017] It is an object of the present invention to provide a rotor assembly for a motor, particularly a hub motor for an electric vehicle, which is compact, lightweight and performs with higher efficiency. It is also an object of the present invention to provide a rotor rim and a rotor ring that is made up of light metals which enhances performance of the rotor assembly due to its lesser 5 weight. It is also an object of the present invention to reduce or avoid use of high precision machines to place magnets, thereby reducing overall cost of the manufacturing of the rotor assembly. Reduced weight provides enhanced range of the vehicle. Another object of the present invention is to simplify and reduce manufacturing time, thereby improving the manufacturing process. Thus, the 10 object of the present invention is to provide light weight rotor assembly which can enhance performance of the hub motor. It is also an object of the present invention to provide less bulky and more efficient rotor assembly especially for applications like electric vehicles where weight matters a lot. It is also an object of the present invention to avoid challenges that come due to requirement of 15 high precision machines for accurate magnet placement therefore the object is to ease manufacturing process. Thus, the object of the present invention is to increase the durability and reliability of the rotor assembly, and consequently of the electric motor.
[00018] The present subject matter along with all the accompanying 20 embodiments and their other advantages would be described in greater detail in conjunction with the figures in the following paragraphs.The present subject matter may be implemented in any two-wheeled, three-wheeled and four-
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wheeled vehicle. However, for the purpose of explanation and by no limitation, the present invention, and corresponding additional advantages and features are described through the following embodiments depicting a two wheeled vehicle. [00019] In an embodiment, the vehicle may be a bike cum scooter type vehicle and may have main frame that extends along the center of the body of 5 the vehicle from a front portion of the vehicle and extending in a rearwardly direction.
[00020] In an embodiment, the vehicle may be a two-wheeled vehicle and may have main frame that extends along the center of the body of the vehicle from a front portion of the vehicle and extending in a rearwardly direction. 10
[00021] Fig. 1 illustrates a perspective view of a rotor assembly (100), in accordance with an embodiment of the present subject matter. Fig. 1 further illustrates parts and components of the rotor assembly (100) in an assembled view. The rotor assembly (100) comprises various components including a rotor rim (102), a rotor ring (104), a separator (106) and a plurality of magnetic 15 elements (108). The Rotor Rim (102) is the outermost component, forming a ring-like structure. It provides structural support and houses the other components. The Rotor Ring (104) component is located inside the rotor rim (102). It is another ring-shaped structure, made of different material. The Separator (106) ensures space between plurality of magnetic elements (108). 20 The magnetic elements (108) are embedded within slots provided by the separator (106). They are arranged in a specific pattern to create a desired magnetic field when the rotor rotates.
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[00022] Fig. 2 illustrates an exploded view of the rotor assembly (100), in accordance with an embodiment of the present subject matter. The exploded view of the rotor assembly (100) illustrates each of the components of the rotor assembly (100) in detail. In an embodiment, the rotor ring (104) is coupled to the rotor rim (102). The separator (106) is coupled to the rotor ring (102). The 5 separator (106) comprises a plurality of slots (106s) to accommodate the plurality of magnetic elements (108). In an embodiment, the rotor rim (102) is made up of a first material and the rotor ring (104) is made up of a second material. In an embodiment, the first material is steel or aluminum, and the second material is medium carbon steel. The use of such material helps to 10 achieve significant reduction in weight and thereby enhances the overall performance of the rotor assembly.
[00023] Fig. 3 illustrates a perspective view of a rotor ring (104), in accordance with an embodiment of the present subject matter. In one embodiment, the rotor ring (104) comprises one or more first grooves (104g) 15 extended circumferentially. The one or more first grooves (104g) extending circumferentially on an outer surface of the rotor ring (104). The proposed hub motor design uses a uniquely designed rotor ring with material removed at strategic locations without sacrificing strength and electromagnetic implications. This results in a significant reduction in the weight of the rotor 20 ring (104), resulting in resulting in reduction of weight of the motor without compromising its performance.
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[00024] Fig. 4 illustrates a perspective view of a separator (106) having open slots (106so), in accordance with an embodiment of the present subject matter. Fig. 5 illustrates a perspective view of the separator (106) of the rotor assembly (100) having closed slots (106sc), in accordance with an embodiment of the present subject matter. Fig. 4 and Fig. 5 shall be explained together for sake of 5 brevity. The separator (106) comprises a plurality of slots (106s) to accommodate plurality of magnetic elements (108). The separator offers advantages such as reduced cogging torque. Cogging torque is a type of undesirable torque ripple that occurs in permanent magnet motors due to the interaction between the permanent magnets and the stator teeth. Having gaps 10 between the magnetic elements reduces the strength of this interaction, leading to a smoother torque profile and reduced vibration. The gaps between the magnetic elements help to create a more uniform magnetic flux distribution within the rotor. This can improve the efficiency of the motor and reduce torque ripple. Gaps between the magnetic elements help create air passageways within 15 the rotor. This airflow assists in dissipating heat generated within the rotor, helping prevent overheating and potential damage to the magnets. Introducing gaps between magnetic elements can ease the manufacturing and assembly process of the rotor, especially for complex geometries.
[00025] In an embodiment, the separator (106) comprises at least one ring 20 shaped member (106c) and a plurality of protrusions (106w) with a gap therebetween to form the slots (106s). In an embodiment, the slots (106s) can be open slots (106so) which are open from one side, as shown in Fig. 4. In
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another embodiment, the slots (106s) can be closed slots (106sc) which are closed from opposite sides, as shown in Fig. 4. [00026] Fig. 6 illustrates a perspective view of the rotor ring (104) of the rotor assembly (100), in accordance with another embodiment of the present subject matter. The rotor ring (104) comprises plurality of second grooves 5 (104t) provided intermittently to mount other components. In an embodiment, the rotor ring (104) comprises the plurality of second grooves (104t) having openings (104o) to screw the other components. The grooves are uniquely designed and provided at predetermined locations/ strategic locations to reduce weight of the rotor ring without sacrificing strength and electromagnetic 10 implications of the motor. This results in a significant reduction in the weight of the motor without compromising its performance. In one embodiment, the plurality of second grooves (104t) are configured at a regular interval or space therebetween. In another embodiment, the plurality of second grooves (104t) are configured intermittently. In an embodiment, the rotor ring (104) comprises 15 one or more third grooves (104s) extended circumferentially on another side opposite to the plurality of second grooves (104t).
[00027] Fig. 7 illustrates a top view of the rotor assembly (100), in accordance with an embodiment of the present subject matter. Fig. 8 illustrates a sectional view of the rotor assembly (100), in accordance with an embodiment 20 of the present subject matter. Fig. 7 and Fig. 8 shall be explained together. The top view of the rotor assembly (100) illustrates the rotor rim (102), the rotor ring (104) and the separator (106). An axis AA passing through the rotor
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assembly (100) is also shown. Sectional view of the rotor assembly (100) illustrates a gap (805). In an embodiment, the rotor rim (102) and the rotor ring (104) are arranged such that the gap (805) is provided between a side portion of the rotor ring (104) and a side portion of the rotor rim (102). In an embodiment, the one or more first grooves (104g) are provided on the rotor ring (104) such 5 that the one or more first grooves (104g) are facing the gap (805) formed between the rotor rim (102) and the rotor ring (104). The gap (805) ensures prevention of water accumulation in the grooves (104g) and thereby improves durability and life of the rotor assembly (100). [00028] Fig. 9 illustrates a perspective view of a vehicle (900) having the 10 rotor assembly (100), in accordance with an embodiment of the present subject matter. In an embodiment, the vehicle (900) comprises an electric motor (902). For instance, the electric motor (902) is a hub motor configured with a rear wheel of the vehicle (900) and acts as prime mover of the vehicle to move the vehicle. The motor (902) is operated by receiving power from a battery pack 15 (not shown) of the vehicle (900) to move the vehicle.
[0001] Thus, the present subject matter offers an advantage of providing a rotor assembly for a motor which is compact, lightweight and has higher efficiency. Another advantage of the present invention is that the components of the rotor assembly are made up of light metals which enhances performance 20 of the rotor assembly due to its lesser weight. Another advantage of the present invention is having reduced weight which reduces power consumption and provides a higher range of the vehicle. Another advantage of the present
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invention is simplification and improvement in the manufacturing process. The present invention provides elimination of usage of high precision machines for magnet placement which also contributes significantly to reduce overall cost of the manufacturing process of the rotor assembly. The present subject matter offers fixed or uniform gap between plurality of magnetic elements that help in 5 achieving a more balanced magnetic force distribution around the rotor thereby reducing the chances of uneven forces that could cause vibration or noise. Fixed gaps contribute to the stability of the rotor, ensuring that there is a consistent magnetic field for optimal motor operation. With a fixed gap, the torque produced by the motor is more consistent, leading to smoother operation and 10 potentially improved overall efficiency. Separator offers spacing between the plurality of magnetic elements. Separator will decrease the dependence on high precision machines so results in saving the fixed cost for high precision machines so simplifies manufacturing processes. [0002] Even spacing between magnets can help reduce cogging torque, 15 which refers to the resistance felt by the motor when trying to start rotating from a standstill. Lower cogging torque can result in smoother startups and potentially better low-speed performance. Even spacing leads to a more uniform torque output, reducing torque ripple. Torque ripple is the fluctuation in torque during each revolution and minimizing it can result in smoother motor 20 operation. An evenly distributed magnetic field might contribute to better overall motor efficiency, especially at varying speeds. It is also an advantage of the present invention to have lighter motors, improved efficiency, and less prone
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to breaking. It is also an advantage of the present invention to have less bulky and more efficient rotor assembly especially for applications like electric vehicles where weight matters a lot. It is also an advantage of the present invention to have ease in the manufacturing process. Another advantage is having better heat dissipation by using metals which have more thermal 5 expansion. Thus, the advantage of the present invention is to increase the durability and reliability of the rotor assembly. [0003] While certain features of the claimed subject matter have been illustrated and described herein, many modifications, substitutions, changes, and equivalents will now occur to those skilled in the art. It is, therefore, to be 10 understood that the appended claims are intended to cover all such modifications and changes that fall within the true spirit of the claimed subject matter.
[0004] In light of the abovementioned advantages and the technical advancements provided by the disclosed subject matter, the claimed steps as 15 discussed above are not routine, conventional, or well understood in the art, as the claimed steps enable the following solutions to the existing problems in conventional technologies. Further, the claimed steps clearly bring an improvement in the functioning of the configuration itself as the claimed steps provide a technical solution to a technical problem. 20
[0005] The proposed solution for weight reduction through selective removal of material from specific locations on the rotor ring is not considered obvious to a person skilled in the art due to its innovative approach. This method
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distinguishes itself by preserving electromagnetic characteristics and maintaining mechanical strength, a departure from conventional weight reduction strategies. The non-obviousness lies in the nuanced balance achieved between weight reduction and performance preservation, making it a novel and inventive solution in rotor design. 5 [0006] A description of an embodiment with several components in communication with another does not imply that all such components are required, On the contrary, a variety of optional components are described to illustrate the wide variety of possible embodiments of the invention.
[0007] Finally, the language used in the specification has been principally 10 selected for readability and instructional purposes, and it may not have been selected to delineate or circumscribe the inventive subject matter and is therefore intended that the scope of the invention be limited not by this detailed description, but rather by any claims that issue on an application based here on. Accordingly, the embodiments of the present invention are intended to be 15 illustrative, but not limiting, of the scope of the invention, which is set forth in the following claims.
[0008] While various aspects and embodiments have been disclosed herein, other aspects and embodiments will be apparent to those skilled in the art. The various aspects and embodiments disclosed herein are for purposes of 20 illustration and are not intended to be limiting, with the true scope and spirit being indicated by the following claims.
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[0009] While the present disclosure has been described with reference to certain embodiments, it will be understood by those skilled in the art that various changes may be made, and equivalents may be substituted without departing from the scope of the present disclosure. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the present 5 disclosure without departing from its scope. Therefore, it is intended that the present disclosure not be limited to the particular embodiment disclosed, but that the present disclosure will include all embodiments falling within the scope of the appended claims.
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Reference Numerals:
100 –rotor assembly
102- rotor rim
104- rotor ring
104g- one or more first grooves 5
104t- plurality of second grooves
104s- one or more third grooves
104o- openings
106- separator
106c- ring shaped member 10
106s- one or more slots
106so- open slots
106sc- closed slots
106w- plurality of protrusions
108- plurality of magnetic elements 15
805- gap
900- vehicle
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902- electric motor , Claims:We claim:
1. A rotor assembly (100) for an electric motor, the rotor assembly (100) comprising:
a rotor rim (102); 5
a rotor ring (104) coupled to the rotor rim (102); and
a separator (106) coupled to the rotor ring (102), wherein the separator (106) comprises a plurality of slots (106s) to accommodate plurality of magnetic elements (108).
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2. The rotor assembly (100) as claimed in claim 1, wherein the rotor rim (102) being made up of a first material and the rotor ring (104) being made up of a second material, wherein the first material being steel and the second material being medium carbon steel.
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3. The rotor assembly (100) as claimed in claim 1, wherein the rotor ring (104) comprises one or more first grooves (104g) arranged circumferentially.
4. The rotor assembly (100) as claimed in claim 3, wherein the rotor rim 20 (102) and the rotor ring (104) are arranged such that at least one gap (805) is provided between a side portion of the rotor ring (104) and a side portion of the rotor rim (102).
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5. The rotor assembly (100) as claimed in claim 4, wherein the one or more first grooves (104g) are provided on the rotor ring (104) such that the one or more first grooves (104g) are facing the gap (805) formed between the rotor rim (102) and the rotor ring (104).
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6. The rotor assembly (100) as claimed in claim 1, wherein the rotor ring (104) comprises a plurality of second grooves (104t), the plurality of second grooves (104t) being configured spaced apart.
7. The rotor assembly (100) as claimed in claim 1, wherein the separator 10 (106) comprises at least one ring shaped member (106c) and a plurality of protrusions (106w) with a gap therebetween to form the one or more slots (106s).
8. The rotor assembly (100) as claimed in claim 1, wherein the plurality of 15 slots (106s) are either open slots (106so) which are open from one side, or closed slots (106sc) which are closed from opposite sides.
9. A vehicle (900) comprising:
an electric motor (902), the electric motor (902) comprising a 20 stator assembly and a rotor assembly (100),
wherein the rotor assembly (100) comprises:
a rotor rim (102);
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a rotor ring (104) coupled to the rotor rim (102); and
a separator (106) coupled to the rotor ring (102), wherein the separator comprises a plurality of slots (106s) to accommodate plurality of magnetic elements (108).
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10.The vehicle as claimed in claim 9, wherein the electric motor (902) is ahub motor.