FIELD OF INVENTION
[0001] The present invention relates to a structure of a motor. More specifically, the present invention relates to a lamination design for a stator member of the motor using wound bobbin coil.

BACKGROUND OF THE INVENTION
[0002] Electric motors are comprised of two main components namely a rotor and a stator. Electric motors of brushless type include a permanent magnet rotor operating in synchronism with a rotating magnetic field created by a continuous electric current flowing through stator windings.
[0003] Brushless motors are widely replacing the commonly used Induction Motors in appliances that need working for long durations such as air conditioners and fans, wherein the brushless motors offer higher efficiency, long product life. Brushless motors also offer minimal electromagnetic interference or radio frequency interference noise when compared to motors with brushes.
[0004] A conventional stator of an electric motor comprises a number of salient poles, which are operatively coupled with a stator core, wherein the poles are directed substantially radially, starting from the yoke whereto they are rigidly coupled, toward the inside of the stator. Each pole also has, at its end, a pole shoe. The pole shoes surround the rotor without contact, i.e., they are arranged so that a cylindrical interspace is maintained between the pole shoes and the rotor. Furthermore, an excitation winding is arranged around each one of the poles and is constituted by an adapted number of turns of insulated conducting wire which, when electric current flows there through, induces in the stator an electromagnetic force that produces the rotation of the rotor.
[0005] Known methods for lamination design for a rotor motor comprises of winding of each pole separately by sliding a winding wire over a fixture such that it drops into a desired slot. This method of winding is slow and inefficient as it enables winding of merely one or two slots at a time due to the complexity of fixture.
[0006] In general, the structure of a stator in external rotor motor as shown in FIG. 1a and includes a number of poles extending radially outward from an annular ring with a circular space in the centre of the ring for accommodating the shaft of rotor. Similarly, for internal rotor motor, the stator structure as shown in FIG.1b comprises of a plurality of pole members radially inwards from periphery, thereby forming a circular space (rotor hole) in the centre for accommodating the rotor magnet.
[0007] In addition, motor lamination design known in prior-art poses numerous limitations such as need for individual winding for each phase followed by soldering or crimping to form joints between bobbins which results in increased cost and low productivity. In addition to Fig. 1, Fig. 4(b) also illustrates conventional brushless external rotor motor assembly showing stator with the windings on the poles, a shaft hole within the stator body, wherein the stator is covered by an external rotor by means of a magnet. Similarly, Fig. 5(b) illustrates a conventional internal rotor motor assembly showing a stator having poles encompassing the rotor (magnet), wherein the center the rotor body includes a shaft hole for receiving a shaft. Between the shaft hole and the rotor is configured an adaptor ring. As can be seen and understood, using the existing technologies, the windings on each pole has to be done by sliding the winding wire over a fixture such that it drops into the desired slot. Such a mechanism is slow and typically winds one or two slots at a time due to the complexity in fixturing.
[0008] Therefore, there still exists a need for an efficient lamination design of motor, especially the stator part of the motor that carries winding of the motor and printed circuit board used for implementing embedded electronics and in order to overcome the above mentioned disadvantages of the above mentioned conventional lamination design of motor.

OBJECTS OF THE INVENTION
[0009] It is an object of the present invention to provide a novel lamination design that offers reduced material content and higher productivity in the manufacturing process without compromising on motor performance.
[00010] It is an object of the present invention to provide a lamination design that can accommodate use of separately wound bobbins that can be slid over pole shoes for faster motor winding and assembly.
[00011] It is an object of the present invention to provide a lamination design in which all pole shoes can be assembled in the annular ring of lamination in one operation.
[00012] It is an object of the present invention to provide capability to use bobbins for winding such that all phases are wound simultaneously and that within one phase all bobbins can be wound consecutively with no need to solder/ crimp winding wires to form joints between bobbins.
[00013] It is an object of the present invention to protect individual wound bobbin coils by automatically taping an insulation material over the winding, thus providing inter-coil insulation.
[00014] It is an object of the present invention to provide a design that can use prevailing machinery and techniques to reduce cost of machinery and fixtures required per wound motor by use of high speed, low cost winding techniques and with winding of all phases of motor simultaneously.

SUMMARY OF THE INVENTION
[00015] According to an embodiment of the present invention, there is provided a stator of an external rotor motor comprising: a stator core made of an annular ring with a circular space in its center to accommodate a shaft of an external rotor motor; a plurality of slots on outer periphery of the annular ring configured to hold one or more pole shoes extending outwards in radial direction perpendicular to a rotational axis of the rotor shaft and a bobbin assembly wound with an electrical conducting material slipped over each of the pole shoe.
[00016] According to another embodiment, the present invention also provides a stator of an internal rotor motor comprises a stator core made of an annular ring with multiple slots on the inner periphery of the ring and configured to hold pole shoes extending inwards in a radial direction thereby forming a circular space in the centre to accommodate a rotor of the internal rotor motor, and a bobbin assembly wound with an electrical conducting material slipped over each of the pole shoe.
[00017] According to an embodiment, pole shoes are designed complementarily to fit in the slots of the annular ring such that the pole shoes are held firmly in place with proper alignment, wherein orientation of the pole shoe is dependent on the location of the slots on either outer or inner periphery of the annular ring.
[00018] According to an embodiment, the annular ring is operatively coupled with a magnet such that the magnet (configured to function as a rotor) is positioned on the outer side of the ring for an external rotor motor and on the inner side of the ring for an internal rotor motor. The annular ring for the external rotor motor also has a central circular space to accommodate the rotor shaft.
[00019] According to another embodiment, bobbins for motor windings can be used such that they can be wound collectively, without joints, resulting in a process that has high volume production capability.
[00020] Various objects, features, aspects and advantages of the inventive subject matter will become more apparent from the following detailed description of preferred embodiments, along with the accompanying drawing figures in which like numerals represent like components.

BRIEF DESCRIPTION OF THE DRAWINGS
[00021] In the Figures, similar components and/or features may have the same reference label. Further, various components of the same type may be distinguished by following the reference label with a second label that distinguishes among the similar components. If only the first reference label is used in the specification, the description is applicable to any one of the similar components having the same first reference label irrespective of the second reference label.
[00022] Fig. 1a and Fig. 1b illustrate conventional (prior art) stator structures for external and internal rotor motors respectively.
[00023] Fig. 2a, Fig. 2b, and Fig. 2c illustrate an annular laminating ring for an external rotor having slots that are configured to fit in one or more pole shoes.
[00024] Fig. 3a, Fig. 3b, and Fig. 3c illustrate an annular laminating ring for an internal rotor motor having slots that are configured to fit in one or more pole shoes.
[00025] Fig. 4a and Fig. 4b illustrate the proposed motor assembly and the conventional (prior art) motor assembly respectively for an external rotor motor.
[00026] Fig. 5a and Fig. 5b illustrate the proposed motor assembly and the conventional (prior art) motor assembly respectively for an internal rotor motor.
[00027] Fig. 6 illustrates exemplary shapes of annular lamination rings.
[00028] Fig. 7 illustrates exemplary shapes of pole shoes.
[00029] Fig. 8 illustrates conventional (prior art) utilization schedule for lamination material.
[00030] Fig. 9a and Fig. 9b illustrate material utilization using the proposed annular lamination ring and pole shoe respectively.
[00031] Fig. 10a and Fig. 10b illustrate conventional stator with molded insulation components.
[00032] Fig. 11a and Fig. 11b illustrate conventional stator with plastic sheet insulation.
[00033] Fig. 12a and Fig. 12b illustrate stator in accordance with one embodiment of the present invention.
[00034] Fig. 13 illustrates typical winding connections in the proposed motor in accordance with one embodiment of the present invention.
[00035] Fig. 14 illustrates an exemplary winding mandrel with multiple bobbins in accordance with one embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION
[00036] According to an embodiment of the present invention, there is provided a stator of an external rotor motor comprising: a stator core made of an annular ring with a circular space in its center to accommodate a shaft of an external rotor motor; a plurality of slots on outer periphery of the annular ring configured to hold one or more pole shoes extending outwards in radial direction perpendicular to a rotational axis of the rotor shaft and a bobbin assembly wound with an electrical conducting material slipped over each of the pole shoe.
[00037] According to another embodiment, the present invention also provides a stator of an internal rotor motor comprises a stator core made of an annular ring with multiple slots on the inner periphery of the ring and configured to hold pole shoes extending inwards in a radial direction thereby forming a circular space in the center to accommodate a rotor and shaft of the internal rotor motor, and a bobbin assembly winded wound with an electrical conducting material slipped over each of the pole shoe.
[00038] Following description is described with respect to various embodiments of the present inventive subject matter. One skilled in the art will recognize that the inventive subject matter can scale as necessary to any number of items without departing from the inventive subject matter.
[00039] In the following description, numerous specific details are set forth in order to provide a thorough understanding of embodiments of the present invention. It will be apparent to one skilled in the art that embodiments of the present invention may be practiced without some of these specific details.
[00040] If the specification states a component or feature “may”, “can”, “could”, or “might” be included or have a characteristic, that particular component or feature is not required to be included or have the characteristic.
[00041] Fig. 2a, Fig. 2b, and Fig. 2c illustrate an annular laminating ring for an external rotor having slots that are configured to fit in one or more pole shoes. More specifically, Fig. 2a shows an annular lamination ring of a stator in accordance with an embodiment of the present invention, wherein the ring comprises multiple slots. As would be seen in subsequent representations, shape of the slots present in the ring can be varied as per user convenience and any other locking mechanism between the slots of the annular ring and the pole shoe (as shown on Fig. 2b) can be configured. The pole shoe of Fig. 2b can also be configured in any desired size and shape such that it fits and locks within the annular ring of the stator. Fig. 2c represents the pole shoe of the stator assembly as fitted into the slots of the annular ring. It would also be appreciated that although Fig. 2 represents as many pole shoes as the slots on the ring, in practicality, the number of pole shoes can be different from the number of slots on the ring. As can further be seen, the annular ring comprises a hole in the center, which is configured to receive a rotor shaft. Complete structure of the proposed external rotor motor has been shown in Fig. 4a and would be explained below.
[00042] Fig. 3a, Fig. 3b, and Fig. 3c illustrate an annular laminating ring for an internal rotor motor having slots that are configured to fit in one or more pole shoes. More specifically, stator of the internal rotor motor comprises an annular ring having a plurality of slots on the inner periphery of the ring. The slots, as mentioned above for Fig. 2 can be of any shape, size, dimension, or construction, such that pole shoes (Fig. 3b) can be fitted and locked into one or more slots of the annular ring. As shown in Fig. 3c, once the pole shoes have been fitted into the internal slots of the ring, an internal circular hole is formed, wherein the hole comprises one or more magnets to act as rotors that can be mounted on the periphery of the annular ring, an adaptor ring, and a shaft hole configured to receive the rotor shaft. Complete structure of the proposed internal rotor motor has been shown in Fig. 5a and would be explained below.
[00043] Fig. 4a illustrates the proposed motor assembly showing an external rotor, wherein the assembly shows a stator having an annular ring that has a plurality of slots configured to receive one or more pole shoes, wherein each pole shoe has bobbin winding on it. Any number of shoes can be configured onto the annular ring based on change in construction of slots of the ring. In a preferred embodiment, the number of slots/pole shoes range from 2 to 48. The annular ring can be configured with a hole (shaft hole) to receive the rotor shaft. The annular ring can be operatively coupled with a magnet, which acts as a rotor, wherein the magnet(s) can be assembled in an external sleeve. Comparison of Fig. 4a showing the proposed stator design can be done with the conventional stator design of Fig. 4b in which the completely lamination structure of the stator comprises a fixed body of annular ring fixedly coupled with the pole shoes, making the existing solutions in-efficient in manufacturing, have relatively higher material consumption, difficult for winding, and having problems during insulation of winding.
[00044] Fig. 5a illustrates the proposed motor assembly showing an internal rotor, wherein the assembly shows a stator having an annular ring that has a plurality of slots (towards its inner circumference end) configured to receive one or more pole shoes, wherein each pole shoe has bobbin winding on it. Any number of shoes can be configured onto the annular ring based on change in construction of slots of the ring. In a preferred embodiment, the number of slots/pole shoes range from 2 to 48. The annular ring can be configured with a hole (rotor hole) to receive the magnet(s). The annular ring can be operatively coupled with a magnet, which acts as a rotor, wherein the magnet(s) can be assembled by means of a lamination ring and configured towards the inner end of the annular ring. Comparison of Fig. 5a showing the proposed stator design can be done with the conventional stator design of Fig. 5b in which the completely lamination structure of the stator comprises a fixed body of annular ring fixedly coupled with the pole shoes, making the existing solutions non-efficient in operation, difficult for winding, and having problems during insulation of winding.
[00045] Fig. 6 illustrates different shapes of slots that can be configured with the annular ring of the stator. Each slot, as can be seen, in each figure of Fig. 6 has a different shape and therefore slots with different sizes, constructions, structures, and dimensions can also be configured. Any number of slots can be configured in each annular ring based on user preference and end application. Exemplary annular rings of Fig. 6 include 9 slots. Although the present example has been shown with respect to a stator for an external rotor motor, a similar structure of status ring can also be designed for an internal rotor motor. Fig. 7, on the other hand, illustrates multiple designs of pole shoes that can fit into corresponding slots of the annular rings.
[00046] Fig. 8 illustrates conventional (prior art) utilization schedule for external rotor lamination material. The conventional stator lamination as shown in Fig. 8 is a single unit piece having 9 poles, each stator can be seen as having a diameter of 100 mm. Fig. 9a and Fig. 9b, on the other hand, show the proposed stator lamination construction wherein the pole shoes are separated in the manufacturing step itself from the annular ring and therefore illustrate efficient material utilization using the proposed annular lamination ring and pole shoe respectively. With the lamination being broken into multiple components for external rotor motor, the lamination tool layout can be modified to take advantage of the proposed design. The annular ring (first component) of the proposed design is shown Fig. 9a and the pole shoes (second components) are shown in Fig. 9b. As can be seen from Fig. 9a, diameter of the annular ring, when manufactured separately for incorporating 9 slots, is 51mm, whereas the length of the pole shoe is 30.50mm, making the total length of the stator when the annular ring fits the pole shoes to be around 81.50mm, which gives a 20% savings on the stator lamination shown in Fig. 8. Furthermore, in an embodiment, as the laminations become larger, the savings will increase. Pole shoe designs can also be optimized to take further advantage of the proposed stator structure.
[00047] Fig. 10a and Fig. 10b illustrate conventional laminations with epoxy coated stator/molded insulation components. As would be appreciated, laminations are used to make stacks of desired thickness, wherein internal or external winding is done directly on the stack after suitable insulation means are put in place. Fig. 10a and Fig. 10b illustrate conventional lamination stacks using molded insulation components placed on either side of the stack. Instead of molded insulation components, Epoxy coating over the stack in winding area can also be done. Fig. 11a and 11b also illustrate conventional laminations with use of plastic sheet insulation. As illustrated, polyester, Nomax paper or other such insulation sheet materials can be used in desired shape and inserted into the winding slot.
[00048] Fig. 12a and Fig. 12b illustrate lamination in accordance with one embodiment of the present invention. With the proposed lamination design and use of individual bobbins per pole as insulation media and a means to implement winding on the bobbins, there is no need for in-situ winding and, therefore, there is no need for slow multi-axes start and stop motion. Fig. 13 shows the proposed winding connections in an embodiment of the present embodiment having 9 slots in the annular ring. As can be seen, winding for all the 3 phases can be done simultaneously and all distributed pole positions can be consecutively wound for all 3 phases, as shown in Fig. 14. In order to protect individual wound bobbin coil, the insulation material can be taped over the winding itself, thereby providing inter-coil insulation. Desired phase-to-phase interconnections of wound bobbins can also be done subsequently, by various commonly used techniques, after bobbin insertion in pole shoes and assembling the pole shoes in the inner Core. According to one embodiment, high-speed machines can wind at speeds 3 to 10 times faster using this approach making the process acceptable for lower cost and enabling high volume manufacturing. Further, use of bobbins is particularly important for motors designed for high voltage applications e.g. motors operating at 115, 230V, or 400V AC/ DC Supply.
[00049] While embodiments of the present disclosure have been illustrated and described, it will be clear that the present disclosure is not limited to these embodiments only. Numerous modifications, changes, variations, substitutions, and equivalents will be apparent to those skilled in the art, without departing from the spirit and scope of the present disclosure, as described in the claims.

ADVANTAGES OF THE INVENTION
[00050] The present invention provides a novel lamination design that offers reduced material content and higher productivity in the manufacturing process without compromising on motor performance.
[00051] The present invention provides a lamination design that can accommodate use of separately wound bobbins that can be slid over pole shoes for faster motor assembly.
[00052] The present invention provides a lamination design in which all pole shoes can be assembled in the annular ring of lamination in one operation.
[00053] The present invention provides capability to use bobbins for winding such that all phases are wound simultaneously and that within one phase all bobbins can be wound consecutively with no need to solder/ crimp winding wires to form joints between bobbins.
[00054] The present invention protects individual wound bobbin coils by automatically taping an insulation material over the winding, thus providing inter-coil insulation.
[00055] The present invention provides a design that can use prevailing machinery and techniques to reduce cost of machinery and fixtures required per wound motor by use of high speed, low cost winding techniques and with winding of all phases of motor simultaneously.

CLAIMS:I CLAIM:

1. A motor comprising a stator core having an annular ring with a circular space in its center to accommodate a shaft of an external rotor motor; a plurality of slots on outer periphery of the annular ring configured to hold one or more pole shoes extending outwards in radial direction.
2. The motor of claim 1, wherein the stator further comprises a bobbin assembly wound with an electrical conducting material slipped over each of the pole shoe.
3. The motor of claim 1, wherein the bobbin assembly is wound before the one or more pole shoes are configured in the respective plurality of slots of the annular ring.
4. The motor of claim 1, wherein the plurality of slots are of multiple shapes, sizes, and dimensions, and the one or more pole shoes are configured such that they fit and lock into the different shapes, sizes, and dimensions of the plurality of slots.
5. The motor of claim 1, wherein the one or more pole shoes slide into the plurality of slots in one operation.
6. The motor of claim 1, wherein bobbins are used for winding such that all phases are wound simultaneously.
7. The motor of claim 1, wherein the motor is a brushless motor.
8. The motor of claim 1, wherein number of pole shoes range from 2 to 48.
9. A motor comprising a stator core having an annular ring with a circular space in its center to accommodate a shaft of an internal rotor motor; a plurality of slots on inner periphery of the annular ring configured to hold one or more pole shoes extending inwards in radial direction.
10. The motor of claim 9, wherein the stator further comprises a bobbin assembly wound with an electrical conducting material slipped over each of the pole shoe.
11. The motor of claim 9, wherein the bobbin assembly is wound before the one or more pole shoes are configured in the respective plurality of slots of the annular ring.
12. The motor of claim 9, wherein the plurality of slots are of multiple shapes, sizes, and dimensions, and the one or more pole shoes are configured such that they fit and lock into the different shapes, sizes, and dimensions of the plurality of slots.
13. The motor of claim 9, wherein the one or more pole shoes slide into the plurality of slots in one operation.
14. The motor of claim 9, wherein bobbins are used for winding such that all phases are wound simultaneously.
15. The motor of claim 9, wherein the motor is a brushless motor.
16. The motor of claim 9, wherein number of pole shoes range from 2 to 48.