Claims:WE CLAIM:
1. A stator assembly (100) of a magneto of a vehicle, the stator assembly (100) comprising:
a stator core (101) having a plurality of radially outward extending stator teeth (102), wherein the stator core (101) comprises a plurality of laminations stacked together;
a plurality of ducts (103) extending perpendicular in direction along a width of the stator core (101), wherein the plurality of ducts (103) are formed on the inner surface of the stator core (101); and
a bobbin assembly (105) having a first part and a second part for encapsulating stator core (101).

2. The stator assembly (100) as claimed in claim 1, wherein the plurality of ducts (103) are at least in helical shape or a spiral shape.

3. The stator assembly (100) as claimed in claim 1, wherein the plurality of ducts (103) have a tapered shape.

4. The stator assembly (100) as claimed in claim 1, wherein the stator core (101) further comprises a plurality of ducts (104) on an external side of the stator core (101).

5. The stator assembly (100) as claimed in claim 1, wherein the bobbin assembly (105) isolates the stator core (101) from stator windings.

6. The stator assembly (100) as claimed in claim 1, wherein the stator assembly (100) is exposed to a fluid-cooling medium, wherein the fluid-cooling medium comprises air or a fluid coolant.

7. A stator assembly (100) of a magneto for a vehicle, the stator assembly (100) comprising:
a stator core (101), wherein the stator core (101) comprises a plurality of radially outward extending stator teeth (102);
a lamination stacking arrangement (106);
a plurality of inner ducts (103) extending along the inner circumference of the stator core (101); and
a bobbin assembly (105) encapsulating stator core (101) to act as a winding isolation assembly.

8. The stator assembly (100) as claimed in claim 7, wherein the plurality of inner ducts (103) have a helical or skewed structure in the direction perpendicular to the circumference of the stator core (101).

9. The stator assembly (100) as claimed in claim 5, wherein the bobbin assembly (105) comprises of bobbin walls (107).

Dated this 03rd Day of November 2021

Priyank Gupta
Agent for the Applicant
IN/PA-1454
, Description:FORM 2

THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENT RULES, 2003

COMPLETE SPECIFICATION

(See Section 10 and Rule 13)

Title of invention:
A STATOR CORE PACK WITH INTEGRATED DUCT

APPLICANT:
Varroc Engineering Limited.
An Indian entity having address as:
L-4, MIDC Waluj,
Aurangabad-431136,
Maharashtra, India

The following specification describes the invention and the manner in which it is to be performed.

TECHNICAL FIELD
The present subject disclosure described herein, in general, relates to automobiles. More particularly, the present subject matter relates to magneto used in automotive applications.

BACKGROUND
For optimal performance, efficiency, and reliability of a magneto, it is necessary to maintain the temperature of the moving/rotating and stationary parts of the magneto. Usually, the stator is a stationary part of the magneto and is enclosed within a rotor housing or a rotor cup, therefore maintaining the optimum temperature becomes challenge.

The electric and the magnetic resistances generated in the stator assembly components, like stator core, core windings, etc., due to the electric current/magnetic force applied thereto causes heat generation in the stator assembly/stator core. Thus, there may be an irreversible deterioration of the components and degradation in the performance of the magneto if the temperature due to this heat generation reaches beyond a predefined operable temperature range. Hence, for maintaining the optimum performance of the magneto, managing the heat generation in the stator assembly is extremely crucial. Various methods of cooling the stator assembly have been proposed and are well-known including an air-cooling method and a fluid cooling method.

The air-cooling method as disclosed in the prior art has an indirect-cooling structure to cool the stator core and the stator core windings. In accordance with the indirect method the heat from the stator is transferred away from the stator toward the outer periphery of the magneto. The transfer of heat is enabled by plurality of fins mounted or integrated with the stator. The ambient air from the surrounding is flown over the plurality of fins to reduce their temperature. As the external air or traveling wind of a vehicle is typically used as a coolant, the problem with air-cooling method is that it is not impossible to control the flow rate of the cooling air depending on the temperature of the magneto.

The fluid-cooling method in accordance with exemplary prior disclosure is also an indirect-cooling method that uses a heat conduction phenomenon between cooling fluid, a housing, and a heat source. In the indirect-cooling fluid method for the magneto the cooling efficiency gets degraded due to the contact state (i.e., contact thermal resistance) between the components.

Therefore, the above-mentioned indirect cooling methods for the stator core temperature reduction have many drawbacks and are inefficient in reducing the high-temperature due to the at least aforementioned reasons.

Further, there is a need to reduce the stator winding temperature of the stator assembly/core so as to maintain and improve the operational efficiency of the stator assembly and the magneto for the vehicle.

The above information disclosed in this background portion is only for improvement in understanding of the background of the disclosure and therefore it may contain information that does not form the related art already known to a person of ordinary skill in the art.

SUMMARY
This summary is provided to introduce the concepts related to a stator/stator core pack with duct design for reducing the stator winding temperature of a magneto for a vehicle by incorporating ‘duct’ design in the stator/stator core pack. This summary is not intended to identify essential features of the claimed subject matter, nor it is intended to use in determining or limiting the scope of claimed subject matter.
In an exemplary implementation a stator assembly (100) of a magneto for a vehicle is disclosed. The stator assembly (100) may comprise a stator core (101). The stator core (101) may further comprise a plurality of radially outward extending stator teeth (102). The stator core (101) as disclosed may further comprise a plurality of laminations stacked together. The stator assembly (100) may comprise a plurality of ducts (103) extending perpendicular in direction along a width of the stator core (101). The plurality of ducts (103) may be formed on the inner surface of the stator core (101). In accordance with the implementation the stator core (101) may comprise a bobbin assembly (105) having a first part and a second part for encapsulating stator core (101).

In another implementation a stator assembly (100) comprising a stator core (101) is disclosed. The stator core (101) may further comprise a plurality of radially outward extending stator teeth (102). The stator assembly (100) may further comprise a lamination stacking arrangement (106). A plurality of inner ducts (103) may be provided on the stator core (101). The plurality of inner ducts (103) may extend along the inner circumference of the stator core (101). The stator core (101) may further be encapsulated by a bobbin assembly (105) to act as a winding isolation assembly.

BRIEF DESCRIPTION OF DRAWINGS
The detailed description is described with reference to the accompanying figures. In the Figures, the left-most digit(s) of a reference number identifies the Figure in which the reference number first appears. The same numbers are used throughout the drawings to refer like features and components.

Figure 1 illustrates a cross-sectional view of a stator assembly, in accordance with an embodiment of a present subject matter.

Figure 2 illustrates a cross-sectional view of duct design on a stator core pack, in accordance with an embodiment of a present subject matter.

Figures 3 illustrates a lamination stacking arrangement, in accordance with an embodiment of a present subject matter.

Figure 4 illustrates a stator assembly with a stator core, in accordance with an embodiment of a present subject matter.

Figure 5 illustrates a cross-section view of a stator core, in accordance with an embodiment of a present subject matter.

DETAILED DESCRIPTION
Reference throughout the specification to “various embodiments,” “some embodiments,” “one embodiment,” or “an embodiment” means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment. Thus, appearances of the phrases “in various embodiments,” “in some embodiments,” “in one embodiment,” or “in an embodiment” in places throughout the specification are not necessarily all referring to the same embodiment. Further, the particular features, structures or characteristics may be combined in any suitable manner in one or more embodiments.

In accordance with an exemplary embodiment of the present disclosure a stator assembly having inner ducts on the stator is disclosed. The ducts are configured to circulate the ambient air from surrounding and expose the stator winding to the air for dissipation of heat. The ducts may have various geometric shape, including circular, helical and tapered. The ducts may be provided on an internal side of the stator core.

In another exemplary embodiment the ducts may be provided on an external side of the stator core too, along with the ducts on the internal side. The ducts may be configured to carry cooling fluid like coolant and expose the winding to the same.

The present embodiment enables an increased life of the components of the stator assembly/magneto as there is reduction in the heat generation due to the electric/magnetic resistance developed as a result of the passage of the electric current/magnetic force

Figure 1 illustrates a stator assembly 100 of a magneto for a vehicle. The stator assembly 100 comprises a stator/stator core 101 having a plurality of radially outward extending stator teeth 102, a plurality of inner ducts 103, a bobbin assembly 105 with bobbin walls 107, and a lamination stacking arrangement 106. The plurality of inner ducts (103) are formed extending along the inner circumference of the stator core (101). The plurality of inner ducts (103) are integrally provided on the stator core (101) to function as an additional cooling arrangement for temperature reduction of the stator core (101) and the stator assembly (100). The plurality of inner (103) may be integrally provided in a direction extending perpendicular to the width direction of the stator core (101) formed on the inner and outer surface of the stator core (101). The plurality of inner 103, are integrally provided into the inner portion of the stator core (101) for effective cooling through ambient air circulation, thereby reducing the stator core (101) temperature. The plurality of inner ducts (103,) may be designed in any shape or size or geometric profile for maximum reduction in the heat generation due to the passage of electric/magnetic force through the stator assembly (100).

In accordance with the exemplary embodiment, there may be a voltage generation due to the electromagnetic field of the stator core 101 called an eddy current. With the eddy current production, there is heat generation in the stator core 101. This results in power loss and diminished performance which can be reduced by insulating the stator core (101). This insulation of the stator core (101) is done by laminating the stator core (101) making the magneto more efficient. Furthermore, the lamination stack arrangement (106) forms the stator core (101) lamination and the duct (104) lamination, which may be of the same or different lamination materials. The lamination stacking arrangement (106) is used for reduction in eddy current losses which further helps in cooling of the stator core (101). The stator assembly (100) may consist of a cooling medium that may be of any kind of fluid, air or oil or any fluid.

Referring to figure 2, illustrates a cross-sectional view of a stator core (201) of a stator assembly (200). As can be seen in Figure 2, the stator core (201) may comprise a plurality of inner 203 and a plurality of outer ducts 204. The stator core 201 may further comprise a plurality of radially outward extending stator teeth (202), and lamination stacking arrangement (206). A duct (203, 204) from the plurality of inner ducts (203) and the plurality of outer ducts (204) is an additional inside cut on the stator core (201) surface. The plurality of inner ducts (203) are formed extending along the inner circumference of the stator core 201.

The plurality of inner ducts (203) integrally provided on the stator core (201) function as an additional cooling arrangement for temperature reduction of the stator core (201) and the stator assembly (200). The plurality of inner ducts 203 may also be considered integrally provided in a direction extending perpendicular to the width direction of the stator core (201) formed on the inner surface of the stator core (201). The plurality of inner ducts 203 and plurality of outer ducts, 204 provided into the winding area and on the non-effective area of the stator core (201) performs effective ambient air circulation which results in reducing the increase in stator core (201) temperature. The plurality of inner 203 and the plurality of outer ducts 204 (103, 104) may be designed in any shape, or size, or geometric profile as required for maximum reduction in the heat generation. The lamination stack arrangement (206) forms the stator core (201) lamination and the outer duct (204) lamination, which may be of the same or different lamination materials. The stator assembly (200) may consist of a cooling medium that may be of any kind of fluid, air or water or oil or any fluid, as a coolant for stator core (201) temperature reduction.

In another embodiment, referring to figure 3, a cross-sectional view of a lamination stacking arrangement (300) of a stator core (301) is shown. The stator core (301) has a plurality of radially outward extending stator teeth (302) (not shown in Figure 3), a bobbin assembly (305) (also not shown in Figure 3), the lamination stacking arrangement (300), and a plurality of inner ducts (303) formed as per any of the aforementioned embodiments. The lamination stacking arrangement (300) comprises a stator core lamination (306a) and a duct lamination (306b) arrangement. The stator core lamination (306a) and the duct lamination (306b) may be of same or different lamination material. The function of the lamination stacking arrangement (300) is to reduce eddy current losses to reduce the heat generation in the stator core (301).

In yet another embodiment, referring to figure 4, a complete stator assembly (400) with a stator/stator core (401) having a plurality of radially outward extending stator teeth (402), a plurality of inner ducts (403), a bobbin assembly (405) with bobbin walls (407), and a lamination stacking arrangement (406) as per any of the aforementioned embodiments is illustrated. A duct (403, 404) from the plurality of inner ducts (403) and the plurality of outer ducts (404) is formed as a helical, spiral, or skewed duct (403, 404) structure. The benefit of the helical or skewed duct (403, 404) structure present in the stator core may increase the efficiency of the cooling effect by the plurality of inner ducts (403) and outer ducts (404) which may consist of a cooling medium that may be of any kind of fluid.

In yet another embodiment, referring to figure 5, a cross-sectional view of a stator assembly (500) with a stator/stator core (501) having a plurality of radially outward extending stator teeth (502), a plurality of helical/skewed inner ducts (503) and a plurality of helical/skewed outer ducts (504), a bobbin assembly (505) with bobbin walls (507), and a lamination stacking arrangement (506) as per the aforementioned embodiment (figure 4) is shown. The number of helical/skewed inner duct 503, and outer duct 504 in the inner cavity of the stator core and on external surface of the stator core respectively may be increased in part or whole in the stator core (501). This may result in improved air circulation following further increase in the stator core (501) temperature reduction.

The embodiments illustrated above, especially related to the stator assembly comprising a stator/stator core having a plurality of radially outward extending stator teeth, a plurality of inner, a bobbin assembly, and a lamination stacking arrangement provide following advantages:
• The stator assembly of a magneto for a vehicle incorporated with a plurality of inner ducts increase the ambient air circulation in the stator assembly resulting in effective cooling of the stator assembly.
• The stator assembly having a plurality of inner and outer ducts with a bobbin assembly and a lamination arrangement reduces the heat generation in the stator core due to electric and magnetic forces more effectively.
• The stator assembly with a plurality of inner improves the performance efficiency of the magneto resulting in an enhanced life of the components of the stator assembly.

Various modifications to the embodiment will be readily apparent to those skilled in the art and the generic principles herein may be applied to other embodiments. However, one of ordinary skill in the art will readily recognize that the present disclosure is not intended to be limited to the embodiments illustrated but is to be accorded the widest scope consistent with the principles and features described herein.

The foregoing description shall be interpreted as illustrative and not in any limiting sense. A person of ordinary skill in the art would understand that certain modifications could come within the scope of this disclosure.

The embodiments, examples and alternatives of the preceding paragraphs or the description and drawings, including any of their various aspects or respective individual feature(s), may be taken independently or in any combination. Features described in connection with one embodiment are applicable to all embodiments unless such features are incompatible.