Claims:We claim:
1. A stator assembly (100) comprising:
a stator unit (1);
wherein, said stator unit (1) comprises a plurality of stator teeth (401);
wherein, said plurality of stator teeth (401) wounded by a wire to form a plurality of stator coils (3);
an insulating device (2,4, 801) disposed onto said stator unit (1) ; and
wherein, said wire routed through said insulating device.

2. The stator assembly (100) as claimed in claim 1, wherein said insulating device (2,4,801)comprises of an inner periphery member and an outer periphery member.
3. The stator assembly (100) as claimed in claim 2, wherein said inner periphery member being a wire holding unit (4).
4. The stator assembly (100) as claimed in claim 2, wherein said outer periphery member being a bobbin unit (2);
wherein, said bobbin unit (2) comprises an upper member (2a), the lower member (2b) and a base portion (201);
wherein, said upper member (2a) and the lower member (2b) comprise of plurality of teeth insulating members (202) to encapsulate said stator teeth (401);
wherein, said teeth insulating members (202) being arranged in a radially manner;
and said teeth insulating members (202) being perpendicular to the base portion (201).
5. The stator assembly (100) as claimed in claim 2, wherein said outer periphery member being a stator slot wedges (801).
6. The stator assembly (100) as claimed in claim 3, wherein said wire holding unit (4) comprises of a plurality of wire routing paths (601,602,603)
wherein, said wire routing paths (601,602,603) being separated by one or more concentric slotted projections (501,502,503,504);
wherein, said one or more concentric slotted projections (501,502,503,504) comprises an outermost concentric slotted projection (501), a second concentric slotted projection (502), a third concentric slotted projection (503) and an innermost concentric slotted projection (504);
wherein, said one or more concentric slotted projections (501,502,503,504) are arranged in a tiered, coaxial and sequential fashion and at a different height; and
one or more wire hooks (505) being attached to an outer surface of said outer most concentric projection (501); and
a slot opening (604) being located in line with a flange gap (203) of a bobbin unit (2).
7. The stator assembly (100) as claimed in claim 1, wherein said wire forms one or more phase lead wires (703,704,705) being routed through wire routing paths (601,602,603) adjacent to the stator coil (3).
8. The stator assembly (100) as claimed in claim 4, said wire holding unit (4) being covered by a cover unit (701);
wherein, said cover unit (701) being provided with one or more passage means (702).
9. The method of assembling a stator assembly (100) comprising the steps of :
inserting an insulating device on a stator teeth (401) of a stator unit (1);
winding stator teeth and a bobbin unit (2) with a wire through a slot opening provided in said insulating device; and
routing one or more phase lead wires (703,704,705) formed out of said wounded wire through wire holding unit. , Description:TECHNICAL FIELD
[0001] The present subject matter generally relates to a stator assembly. The present subject matter specifically but not exclusively relates to a stator assembly of an electric machine such as a BLDC motor.
BACKGROUND
[0002] An electric machine is majorly composed of a stator and a rotor. The rotor for different machines is constructed differently, based on machine topology. The rotor, in one configuration is disposed outside the stator and in another configuration, the rotor is disposed inside the stator.
BRIEF DESCRIPTION OF THE DRAWINGS
[0003] The detailed description is described with reference to an embodiment of a stator assembly of an electric machine such as a motor along with the accompanying figures. The same numbers are used throughout the drawings to reference like features and components.
[0004] Fig. 1 illustrates perspective view of the stator assembly.
[0005] Fig. 2 illustrates a vertical perspective view of the insulating device with a bobbin unit and wire holding unit, as per an aspect of the invention.
[0006] Fig. 3 illustrates a perspective view of the disassembled bobbin unit, as per an aspect of the invention.
[0007] Fig. 4 illustrates an exploded view of the stator unit and the upper member of the bobbin unit, as per an aspect of the invention.
[0008] Fig. 5 illustrates a perspective view of the wire holding unit integrated with the upper member of the bobbin unit without the stator unit, as per an aspect of the invention.
[0009] Fig. 6 illustrates a top view of the stator assembly, as per an aspect of the invention.
[00010] Fig. 7 illustrates an exploded perspective view of the insulating device where the wire holding device has a cover unit to cover the wire holding unit, as per an aspect of the invention.
[00011] Fig. 8 illustrates another embodiment of the present invention wherein the insulating device with wire holding unit on a stator slot wedges, as per an aspect of the invention.
[00012] Fig. 9 illustrates exploded view of the alternate embodiment of the present invention, as per an aspect of the invention.
[00013] Fig. 10 illustrates an exploded view of the alternate embodiment of the present invention, as per an aspect of the invention.
[00014] Fig. 11 illustrates a top view of the stator unit and the stator slot wedges, as per an aspect of the invention.
[00015] Fig. 12 illustrates an exploded view of the stator slot wedges integrated to the wire holding unit, as per an aspect of the invention.
[00016] Fig. 13 illustrates a cross-section of the stator assembly, as per an aspect of the invention.
[00017] Fig. 14 illustrates a flow chart of the assembly if the stator assembly, as per an aspect of the invention.

DETAILED DESCRIPTION
[00018] An electric machine is usually composed of stator and rotor. The rotor for different machines are constructed differently, based on machine topology. The rotor, in one configuration is disposed outside the stator and in another configuration, the rotor is disposed inside the stator.
[00019] The electric motor having an inner rotor configuration have a rotor mounted onto the shaft and comprises plurality of permanent magnets. Whereas in the electric motor having an outer rotor configuration have a rotor surrounding the stator and the rotor have magnets encircling the stator. The stator is an arrangement made up of staked metal laminations, stacked over one another, having stator poles also called stator teeth directing radially in an outward direction. Stator is constructed by stacking the lamination sheets either LASER cut, or stamped. These laminated sheets are usually of the same shape and size all through the length. This forms the extruded look of the stator along the length. The winding is usually done around the stator teeth to result in the desired winding pattern.
[00020] Even before the stator teeth is wounded with the phase winding, the teeth of stator, which is generally made up of steel, needs to be insulated. The winding on each stator tooth is generally made up of cooper metal or the like. The winding over each stator tooth need to be electrically insulated from the stator tooth otherwise it can result in an short circuit.
[00021] After the stator coil winding is completed, each phase comprising of one or more coils which forms a positive wire and a negative wire . The lead wires comprise of a positive terminal and neutral wire comprising all the negative terminals for a star configuration. For a delta configuration all phase terminal wires will form lead wires and there will not be any neutral wire. These lead wires need to be routed within the stator which requires additional space due the number of wires and the space taken for routing the wires in order to bunch then at a specific location. In a known art the lead wires are routed through routing means which are directly mounted on top of the stator coils. But the main disadvantage is that routing lead wires coming out from each stator coil increases the overhang length of the winding which leads to increase in the overall length of a wounded stator which eventually increases the size of an electric machine in which the stator is disposed along with a rotor. Thus there is a need of an improved design of the electric machine which works with a compact winding length overcoming above problems as well as other problems of known art.
[00022] Hence, the present invention dislcoses a compact stator assembly which eliminates the problem associated with the increase in the overhang length of the winding in an electric machine such as a motor.
[00023] An aspect of the present invention provides a stator assembly is disclosed which comprises of a stator unit. The stator unit has stator teeth and the stator teeth is wounded by a wire to form stator coils. The stator teeth are covered by insulating devices such a bobbin unit.
[00024] Another aspect of the present invention provides a stator assembly with an insulating device. The insulating device comprises a wire holding unit. The wire holding unit is integrally disposed on an inner periphery member of the insulating device which reduces the overhang length. The insulating device has an outer periphery member which comprises a bobbin unit in one embodiment and a stator slot wedge in an another embodiment .
[00025] Yet another aspect of the present invention provides a stator assembly with a wire holding unit. The wire holding unit has one or more wire routing paths to route the phase lead wires. The wire routing paths are separated by concentric slotted projections. The concentric slotted projections are an outermost concentric slotted projection, a second concentric slotted projection, a third concentric slotted projection and an innermost concentric slotted projection. The concentric slotted projections are arranged in a tiered, coaxial and sequential fashion and at a different height levels and wire hooks are attached to an outer surface of the outer most concentric projection
[00026] Still another aspect of the present invention provides a stator assembly with a wire holding unit which has slot openings located in line with a flange gap of a bobbin unit. The slot openings allow winding of the wire over the stator teeth. Exemplary embodiments detailing features regarding the aforesaid and other advantages of the present subject matter will be described hereunder with reference to the accompanying drawings. Various aspects of different embodiments of the present invention will become discernible from the following description set out hereunder. Rather, the following description provides a convenient illustration for implementing exemplary embodiments of the invention. 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 specific examples thereof, are intended to encompass equivalents thereof.
[00027] Fig. 1 illustrates a perspective view of the stator assembly (100). The stator assembly (100) comprises a stator unit (1). In an embodiment, the stator unit (1) is circular in shape. The stator unit (1) comprises stator teeth (401) (refer fig 4) onto which a metal wire is wounded in form of coils called the stator coils (3). The stator coil (3) converts the electric energy into mechanical energy and vice a versa based on the concept of electromagnetic induction.
[00028] The voltage fed into the stator coils (3) is controlled by a controller (not shown). In an embodiment, the stator unit (1) is insulated from stator unit (1) by a bobbin unit (2) which forms a part of an insulating device. The insulating device comprises an outer periphery member and an inner periphery member and the outer periphery member comprises a bobbin unit (2) whereas the inner periphery member comprises a wire holding unit (4). The bobbin unit (2) of the insulating device is disposed inside the stator unit (1) and then the metal wire is wound around the bobbin unit (2). The bobbin unit (2) removably integrates with the stator unit (1) by disposing the bobbin unit (2) within the gaps formed by the stator teeth (401). The bobbin unit (2) encapsulates the stator teeth (401) (refer fig. 4) to create an insulation layer over the stator teeth (401) and then the wiring is done over the bobbin unit (2).
[00029] The wire holding unit (4), forming the inner periphery member of the insulating device is configured to face away from the stator unit (1). The insulating device comprising the wire holding unit (4) and the bobbin unit (2) is disposed on top of the stator unit (1). Once the wire is wound around the bobbin unit (2) encapsulating the stator teeth (401), wire from each phase are grouped together and formed into bunches of phase lead wires (5) projecting away from the stator coils (3).
[00030] Fig. 2 illustrates a vertical perspective view of the insulating device with a bobbin unit (2) and wire holding unit (4). The wire holding unit (4) is covered by a cover unit (6). The cover unit (6) is removably attached to the wire holding unit (4). The bobbin unit (2) comprises an upper member (2a) and a lower member (2b). Both the upper member (2a) and the lower member (2b) are provided with teeth insulating member (202). The upper member (2a) is a part of insulating device whereas the lower member (2a) is a separate part. The teeth insulating member (202) are arranged in a radially concentric manner. The teeth insulating member (202) are moulded to a base portion (201) of the upper member (2a) and the lower member (2b). The teeth insulating member (202) gets securely disposed on top of the stator teeth (401) whereas each flange gap (203) accommodates the stator slot (402). The teeth insulating member (202) are perpendicular to the base portion (201) of the upper member (2a) and the lower member (2b). The upper member (2a) is pushed into the stator unit (1) from the upper side of the stator unit (1) and the lower member (2b) is pushed into the stator unit (2) from the lower side of the stator unit (2).
[00031] Fig. 3 illustrates a perspective view of the disassembled bobbin unit (2). The upper member (2a) of the bobbin unit (2) is integrated with the wire holding unit (4). The wire holding unit (4) is located on the inner periphery member of the upper member (2a) of the bobbin unit (2). Therefore, the wire holding unit (4) is not mounted on the top of the stator coils (3) thereby making the stator assembly (100) compact in size by reducing the overhang length. The wire holding unit (4) uses the hollow space (302) (refer fig. 3) of the stator assembly (100) to route the phase wires coming out of the stator coils (3) and keeps the lead wires free from entanglement. The base portion (201) of the upper member (2a) forms a circular vertical wall at the outer periphery member of the upper member (2a). Similarly, the base portion (201) of the lower member (2b) also forms a circular vertical wall at the outer periphery member of the lower member (2b ). The wire holding unit (4) is projecting in an outward axial direction, away from the upper member (2a) of the bobbin unit (2). Between the wire holding unit (4) and the base portion (201) of the upper member (2a) of the bobbin unit (2) a cavity (301) is formed. The cavity (301) accommodates the stator coils (3) which are wound around a teeth insulating member (202) encapsulating the each of the stator teeth (401). The teeth insulating member (202) forms a part of the bobbin unit (2) and functions as an insulating layer between the stator teeth and the wounded wire over the stator teeth to prevent any short circuit. The wire holding unit (4) is annular ring like structure which is hollow and enables an axle to be disposed through the hollow space (302) to attach with a rotor (not shown). The hollows space (302) is surrounded by the stator unit (4).
[00032] Fig. 4 illustrates an exploded view of the stator unit (1) and the upper member (2a) of the bobbin unit (2). The stator unit (1) comprises plurality of stator teeth (401) arranged in a circular fashion. Each of the tooth of the stator are separated by a consistent teeth gap (402). Within the teeth gap (402) the upper member (2a) of the bobbin unit (2) is disposed.
[00033] Fig. 5 illustrates a perspective view of the wire holding unit (4) integrated with the upper member (2a) of the bobbin unit (2) without the stator unit (1). The wire holding unit (4) comprises wire routing paths (601,602,603) (refer para 6) arranged in a tiered fashion. The wire routing paths (601,602,603) are separated by concentric slotted projections (501,502,503,504). The concentric slotted projections (501, 502,503,504) comprise of an outermost concentric slotted projection (501), a second concentric slotted projection (502), a third concentric slotted projection (503) and an innermost concentric slotted projection (504). Each of the concentric slotted projection (501, 502, 503, 504) are arranged in a tiered fashion and at different heights. The concentric slotted projections (501,502,503,504) are arranged in a sequential and coaxial fashion such that each of the concentric slotted projections (501,502,503,504) has a different radii and thereby creating gaps in between each of the consecutive concentric slotted projections (501,502,503,504). On the outer surface of each outermost slotted concentric projections (501) a wire hook (505) is fixedly attached. The wire hook (505) is moulded with the wire holding unit (4) and it is attached to the outer surface of the outer most concentric projection (501). The wire hook (505) supports the neutral phase wires of the stator coils (3).
[00034] Fig. 6 illustrates a top view of the stator assembly (100). The wire holding unit (4) comprises of wire routing paths (601,602,603). The first wire routing path (601) is located between the outermost concentric slotted projection (501) and a second concentric slotted projection (502). The second wire routing path (602) is located between the second concentric slotted projection (502) and the third concentric slotted projection (503) and the third wire routing path (603) is located between the third concentric slotted projection (503) and an innermost concentric slotted projection (504). In an embodiment, the wire routing paths (601,602,603) for a three phase machine enables separating the phase wire and enables proper distribution of the phase wires. Further, the wire holding unit (4) has multiple inlets (605) provided on the surface of the concentric slotted projections (501,502,503,504) which enables the wire to be drawn from different phases of the stator coil (3) of the stator unit (1) and then routed along the wire routing paths (601,602,603).
[00035] The wire holding unit (4) comprises slot openings (604) which are located in line with the flange gap (203) of the bobbin unit (2). The wire holding unit (4) is integrated with the bobbin unit (2) such that the slot openings (604) of the wire holding unit (4) enables the coiling of the wire around the stator teeth (401) without the requirement of first winding coil and then assembling the wire holding unit (4) with the bobbin unit (2). This way the requirement of first winding the coil and then assembling a separate wire holding unit (4) gets eliminated as the wire holding unit (4) comprising the slot opening (604) enables easy and fast winding process. For each flange gap (203) there is a slot opening (604) to enable insertion of a wire to be wound around the stator teeth (401).
[00036] Fig. 7 illustrates an exploded perspective view of the insulating device where a cover unit (701) to cover the wire holding unit (4). The lead wires coming out of multiple phases of the stator coils need to be routed through wire routing paths (601,602,603) and bunched together in groups in order to make the electrical connection convenient. The cover unit (701) is provided with passage means (702) such as holes punched into the cover unit (701). Through the passage means, the phase lead wires (703,704,705) are bunched together and routed out of the wire holding unit (4). The neutral wire (706) is routed around the wire holding unit (4) with the support of the wire hooks (505) mounted at the outer surface of the outermost slotted concentric projections (501). The cover unit (701) keeps all the wire routed through the wire routing paths (601,602,603) intact at one place. The phase lead wires (703,704,705) are routed adjacent to the stator coil (3) so that the space which is not occupied by the stator coil (3) can be occupied by the phase lead wires (703,704,705) without increasing the overhang length and thereby keeps the stator assembly (100) small and compact. The phase lead wires (703,704,705) are routed on the inner periphery member of the wire holding unit (4) and adjacent to the stator coil (3).
[00037] Fig. 8 illustrates another embodiment of the present invention wherein the insulating device comprises of a wire holding unit (4) integrated with a stator slot wedges (801). In alternate embodiment where the bobbin unit (2) is replaced by stator slot wedges (801) then for the insulation is provided between the winding and the stator teeth (401) slot liners (not shown). The slot liners can be made up of pulp material and the such slot liners keeps the stator teeth insulated from the winding wire.. The stator sot wedges (801) are teeth like structure which helps in holding the stator coil (3) at a fixed place after completion of the winding. The stator slot wedges (801) are inserted from the top side of the stator unit (1) and in between the stator teeth (401).
[00038] Fig. 9 illustrates an exploded view of the alternate embodiment of the present invention. The stator teeth (401) arranged in a circular fashion are separated by the teeth gap (402) and the stator slot wedges (801) is adaptively disposed within the teeth gap (402). The stator slot wedges (801) are located at the inner periphery member formed by the stator teeth (401) which makes the stator slot wedges (801) function as a stopper to stop the stator coil (3) coming out from the stator teeth (401). The insulating device comprising the wire holding unit (4) and the stator slot wedges (801) is disposed at the centre of the stator unit (1) instead of top of the stator unit (1). This configuration, in both embodiments as explained in the description, helps in reducing the overhang length of the winding of the stator which reduces the size of the wounded stator therefore making it compact in shape and size. Further, the integrated wire holding unit (4) with the bobbin unit and the stator slot wedges (801) eliminates the assembly time and cost of producing a new part.
[00039] Fig. 10 illustrates a top view of the stator unit (1) and the insulating device with the stator slot wedges (801) and the wire holding unit (4). The stator teeth (401) of the stator unit (1) comprises a head portion (401a) and a stem portion (401b). The stator slot wedges (801) are disposed between the head portion (401a) of a stator tooth and the adjacent stator tooth. The space created between the stator shaft of one stator tooth and the stator shaft of the adjacent stator tooth is occupied by the stator coil (3). With this embodiment, the stator coil (3) remains at a fixed place and position and do not come out of the stator’s teeth gap (402).
[00040] Fig. 11 illustrates an exploded view of the insulating device and the cover unit (701).
[00041] Fig. 12 illustrates a top view of the stator assembly (100) with the phase lead wires (703,704,705) through the wire routing unit (4) of the insulating device after the wire is wounded on to the upper member (2a) of the bobbin unit (2) of the insulating device.
[00042] Fig. 13 illustrates the cross-section of the stator assembly (100).
[00043] Fig. 14 illustrates a flow chart of the stator assembly (100). In step 1401, the insulating device comprising the wire holding unit (4) and the upper member (2a) of the bobbin unit (2) is inserted into the stator teeth (401) of the stator unit (1). In step 1402, the winding of the wire 3 is carried out on the stator teeth (401), with a bobbin (2), through the slot opening provided in the insulating device. In step 1403, the phase lead wires is routed to the wire holding unit (4) of the insulating device.

LIST OF REFERENCE SIGNS

stator assembly (100)
stator unit (1)
stator coils (3)
bobbin unit (2)
stator teeth (401)
wire holding unit (4)
phase lead wires (5)
cover unit (6)
upper member (2a)
lower member (2b)
teeth insulating member (202)
base portion (201)
hollow space (302)
teeth gap (402)
concentric slotted projections (501,502,503,504)
outermost concentric slotted projection (501)
a second concentric slotted projection (502)
a third concentric slotted projection (503)
innermost concentric slotted projection (504)
wire hook (505)
wire routing paths (601,602,603)
inlets (605)
flange gap (203)
passage means (702)
neutral wire (706)
stator sot wedges (801)
head portion (401a)
shaft portion (401b)