Description:FIELD OF THE INVENTION
[001] The present invention generally relates to a machine. More particularly, the present invention relates to a rotary electrical machine.

BACKGROUND OF THE INVENTION
[002] Conventionally, in a vehicle, a separate starter motor and a generator have been used to provide the separate functions of cranking of the internal combustion engine and generating electrical energy from the internal combustion engine. However, integrated starter generators (ISG) are becoming more prevalent wherein a single rotary electrical machine is capable of performing both the starter and the generator function. However, with the increased requirements, there is a need for using a three phase ISG.
[003] Especially with the advent of features like idle start stop, in which an ISG plays a vital role, the ISG needs to be tuned to fit the idle start stop requirements, while being able to perform general starter-generator functions. For example, a larger number of windings are required for generating high voltage at low speed since there is a need to supply electrical current during engine idling condition. Further, winding with a higher diameter coil is required to allow high current during engine cranking. This leads to an increase in the size of the ISG.
[004] If an attempt is made to reduce the size of the ISG, then the number of windings have to be reduced or number of coil turns have to be reduced, which leads to the voltage requirements at low machine RPMs not being met. Similarly, any attempt to reduce the ISG size by reducing the thickness of the stator lamination or by reducing magnet width, the voltage requirements at low machine RPMs are not met. Further, if an attempt is made to reduce the size of the ISG by reducing the diameter of coil winding, then the torque requirements for starting the engine are not met. Furthermore, if an attempt is made to reduce the size of the ISG by reducing magnet thickness, it leads to demagnetization. In addition, if an attempt is made to reduce the size of the ISG by using magnets with stronger magnetization to reduce the number of windings, the cost of the magnets is increased.
[005] Thus, there is a need in the art for a machine which addresses at least the aforementioned problems.

SUMMARY OF THE INVENTION
[006] In one aspect, the present invention is directed towards a machine. The machine has a first member having a plurality of magnets. The machine further has a second member assembly, wherein the first member is configured to rotate concentrically with reference to with the second member assembly. The second member assembly has a yoke being provided radially inward from the first member. The second member assembly further has a plurality of teeth extending radially outward from the yoke. Each of the teeth have a head portion and a stem portion. The head portion is provided radially inward of the first member and radially outward of the yoke. The stem portion extends between the yoke and the head portion such that the stem portion being configured to have a predetermined profile to receive one or more coils.
[007] In an embodiment of the invention, the predetermined profile includes an arcuate shaped profile when the stem portion of the teeth being viewed in a side direction of the machine.
[008] In a further embodiment of the invention, the arcuate shaped profile of the stem portion is defined by two or more imaginary circles to provide predetermined arc length for the stem portion.
[009] In a further embodiment of the invention, the imaginary circles include a first imaginary circle and a second imaginary circle. The first imaginary circle and the second imaginary circle are concentric and have a first predetermined radius and a second predetermined radius respectively.
[010] In a further embodiment of the invention, the first predetermined radius of the first imaginary circle is different from the second predetermined radius of the second imaginary circle to define at least one geometric parameter of the stem portion of the machine.
[011] In a further embodiment of the invention, a first sector of a predetermined angle is formed by a pair of first radii, and a second sector of the predetermined angle is formed by a pair of second radii. The predetermined angle of the first sector is same as the second sector.
[012] In a further embodiment of the invention, an arc length defined in the first sector and an arc length defined in the second sector are different from each other.
[013] In a further embodiment of the invention, a portion of arc length between the yoke and the head portion, and a portion of arc length between the yoke and the head portion, determines a second geometric parameter of the stem portion of the teeth.
[014] In a further embodiment of the invention, the stem portion of the stator teeth have a plurality of grooves provided on an outer face of the stem portion of the teeth and the plurality of grooves are configured to receive the one or more coils.
[015] In a further embodiment of the invention, the grooves are configured to receive the coils of predetermined profile to provide improved fill factor.
[016] In a further embodiment of the invention, the predetermined profile of the coils includes a polygon or round shaped.
[017] In a further embodiment of the invention, an angle of curvature of the stem portion is a second predetermined angle and the second predetermined angle is greater than the predetermined angle, thereby being capable of accommodating a higher number of windings of the coils.
[018] In a further embodiment of the invention, the machine is an integrated starter generator machine for a motor vehicle.

BRIEF DESCRIPTION OF THE DRAWINGS
[019] Reference will be made to embodiments of the invention, examples of which may be illustrated in accompanying figures. These figures are intended to be illustrative, not limiting. Although the invention is generally described in context of these embodiments, it should be understood that it is not intended to limit the scope of the invention to these particular embodiments.
Figure 1 illustrates a front view of a machine, in accordance with an embodiment of the invention.
Figure 2 illustrates a front view of a second member assembly of the machine, in accordance with an embodiment of the invention.
Figure 3 illustrates another front view of the second member assembly configured with grooves for accommodation of coils, in accordance with an embodiment of the invention.
Figure 4 illustrates another front view of the machine, in accordance with an alternative embodiment of the invention.
Figure 5 illustrates a graphical comparison of the emf generated by the machine of the present invention versus emf generated by conventional machines, in accordance with an embodiment of the invention.
Figure 6 illustrates a graphical comparison of the emf generated by the machine of the present invention at different angles of curvature of a stem portion, in accordance with an embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION
[020] The present invention relates to a machine. In particular, the present invention relates to a rotary electrical machine.
[021] Figure 1 illustrates a front view of a machine 100 in accordance with an embodiment of the invention. In an embodiment, the machine 100 is a rotary electrical machine. In an embodiment, the machine 100 is an integrated starter generator machine for a motor vehicle. As illustrated, the machine 100 has a first member 110 having a plurality of magnets 112. In an embodiment, the first member 110 is a rotor of the rotary electrical machine, and the rotor has the plurality of magnets 112. In an embodiment, the first member 110 comprises a plurality of permanent magnets 112 disposed circumferentially spaced apart from each other.
[022] Further, the machine 100 has a second member assembly 120. In an embodiment, the second member assembly 120 is a stator assembly of the rotary electrical machine. Herein, the first member 110 is configured to rotate concentrically with reference to with the second member assembly 120. In an embodiment, the first member 110 is magnetically interacts with the second member assembly 120 for the rotation of the first member 110.
[023] As further illustrated, the second member assembly 120 has a yoke 122. The yoke 122 is provided radially inward from the first member 110. Further, the second member assembly 120 has a plurality of teeth 124. The plurality of teeth 124 extend radially outward from the yoke 122. Herein, the yoke 122 and the teeth 124 make up the stator of the machine 100. In an embodiment, the yoke 122 and the teeth 124 are made up of a soft magnetic ferrite material.
[024] As further illustrated, each of the teeth 124 comprises a head portion 124A and a stem portion 124B. Herein, the head portion 124A is provided radially inward of the first member 110 and radially outward of the yoke 122. The stem portion 124B extends between the yoke 122 and the head portion 124A such that the stem portion 124B is configured to have a predetermined profile to receive the one or more coils 114 (shown in Figure 3). The one or more coils 114 received on the stem portion 124B magnetically interact with the plurality of magnets 112 on the first member 110 for the rotation of the first member 110.
[025] The predetermined profile of the stem portion 124B thus allows for the stem portion 124B to receive a larger number of coil turns as opposed to a conventional stem portion having a straight line profile. The predetermined profile of the stem portion 124B thus allows an increase in the number of coil turns, thus delivering higher electromotive force and thus voltage, without having to increase the diameter of the second member assembly 120 or the stator.
[026] In an embodiment, as illustrated in Figure 1, the predetermined profile includes an arcuate shaped profile when the stem portion 124B of the teeth 124 being viewed in a side direction of the machine 100. The arcuate shaped profile of the stem portion 124B thus allows for a greater surface area for accommodating a larger number of coil turns.
[027] Reference is made to Figure 2, wherein as illustrated, in an embodiment, the arcuate shaped profile of the stem portion 124B is defined by two or more imaginary circles C’ to provide predetermined arc length for the stem portion 124B. In an embodiment, as specifically illustrated in Figure 2, to define the arcuate shaped profile of the stem portion 124B is defined by the imaginary circles C’ including a first imaginary circle C1 and a second imaginary circle C2. Herein, the first imaginary circle C1 and the second imaginary circle C2 are concentric. Further, the first imaginary circle C1 has a first predetermined radius r1 and the second imaginary circle C2 has a second predetermined radius r2.
[028] In an embodiment, the first predetermined radius r1 of the first imaginary circle C1 is different from the second predetermined radius r2 of the second imaginary circle C2 to define at least one geometric parameter of the stem portion 124B of the machine 100. In an embodiment, the second predetermined radius C2 is greater than the first predetermined radius C1. In an exemplary embodiment, the difference between the second predetermined radius C2 and the first predetermined radius C1 defines a width of the stem portion 124B.
[029] In a further embodiment, the angle of curvature of the arcuate shaped profile of the stem portion 124B is defined by a first sector OAB of the first imaginary circle C1, and a second sector OA’B’ of the second imaginary circle C2. The first sector OAB of a predetermined angle (?) is formed by a pair of first radii OA and OB, and the second sector OA’B’ of the predetermined angle (?) is formed by a pair of second radii OA’ and OB’. Herein, the predetermined sector angle of the first sector OAB and the second sector OA’B’ is the same as each other. The predetermined sector angle of the first sector OAB or the second sector OA’B’ thus defines the angle of curvature of the arcuate shaped profile of the stem portion 124B. In an embodiment, the predetermined sector angle of the first sector OAB or the second sector OA’B’ exceeds 5 degrees.
[030] Herein, as is clear, owing to the difference between the first radius r1 and the second radius r2, an arc length AB defined in the first sector OAB and an arc length A’B’ defined in the second sector OA`B` are different from each other. Herein, a portion of arc length AB and a portion of arc length A’B’ determines a second geometric parameter of the stem portion 124B of the teeth 124. Thus, in effect, the portion of the arc length AB between the yoke 122 and the head portion 124A, and the portion of the arc length A’B’ between the yoke 122 and the head portion 124A define the total length of the stem portion 124B available for receiving of the one or more coils 114. Since, this length is greater than conventional profiles of the stem portion 124B, the one or more coils 114 turns can be accommodated.
[031] In an embodiment, as illustrated in Figure 3, to further increase the length of the stem portion 124B that is available for receiving the one or more coils 114, the stem portion 124B comprises a plurality of grooves 130 provided on an outer face of the stem portion 124B of the teeth 124. Herein, the plurality of grooves 130 are configured to receive the one or more coils 114, thereby providing for accommodation of more coil turns. In an embodiment, the grooves 130 are configured to receive the one or more coils 114 of predetermined profile to provide improved fill factor. Herein, fill factor is defined as the ratio of total coil cross section to the area of the core window or the stem portion 124B. In an embodiment, the predetermined profile of the one or more coils 114 includes a polygon or round shaped profile as per requirement.
[032] In an embodiment, as illustrated in Figure 4, an angle of curvature of the stem portion 124B is a second predetermined angle and the second predetermined angle being greater than the predetermined angle (?) as illustrated in Figure 1. As a result, the stem portion 124B with a higher angle of curvature is capable of accommodating a higher number of windings of the one or more coils 114. It is understood that greater is the angle of curvature of the stem portion 124B, greater is the length of the stem portion 124B available for receiving the one or more coils 114, thereby being capable of a higher number of windings of the one or more coils 114.
[033] Figure 5 illustrates a comparison between the emf generated by the machine 100 of the present invention and the emf generated by the conventional rotary machines at different electric tooth angles. An electric tooth angle is a measure of the angle by which the magnetic field has rotated. As is clear from Figure 5, the magnitude of the emf generated by the machine 100 of the present invention is greater than emf generated by the conventional machines at all electric tooth angles due to the higher number of coil turns being accommodated in the machine 100 of the present invention.
[034] Similarly, Figure 6 illustrates a comparison between the emf generated by the machine 100 of the present invention when the angle of curvature of the stem portion 124B is the predetermined angle (?), and the emf generated by the machine 100 of the present invention when the angle of curvature of the stem portion 124B is the second predetermined angle. As is clear from Figure 6, the magnitude of the emf generated by the machine 100 with the second predetermined angle of curvature of the stem portion 124B is greater than emf generated by the machine 100 with the predetermined angle (?) of curvature of the stem portion 124B at all electric tooth angles due to the higher number of coil turns being accommodated in the machine 100 with a greater angle of curvature of the stem portion 124B.
[035] Advantageously, the present invention provides a machine, or a rotary electrical machine in which the total length or the total surface area of the stem portion available for accommodating or receiving the one or more coils is increased due to the predetermined profile of the stem portion. The increased length or increased surface area thus provides for a higher number of coil turns, thus leading to increased efficiency of the machine.
[036] Further, the present invention also provides for accommodation of receiving of a higher number of coil turns without having to increase the size or diameter of the machine. The prevention in size allows for the machine to be efficient while being compact.
[037] Furthermore, in the present invention, the number of coil turns is increased, which results in generation of a higher emf and higher torque. Thus, a reduction in size of the machine is achieved with higher emf and higher torque, thus eliminating the issues of low voltage generation at low RPMs, lower torque generation, demagnetization and increase in costs. Thus, the requirement of reducing windings, reducing umber of coil turns, reducing diameter of coil winding, reducing thickness of stator lamination, reducing magnet thickness, reducing magnet width etc. are all eliminated to achieve a reduction in the size of the machine.
[038] While the present invention has been described with respect to certain embodiments, it will be apparent to those skilled in the art that various changes and modification may be made without departing from the scope of the invention as defined in the following claims.

List of Reference Numerals
100: Machine
110: First Member
112: Plurality of Magnets
114: one or more coils
120: Second Member Assembly
122: Yoke
124: Plurality of teeth
124A: Head Portion
124B: Stem Portion
130: Plurality of Grooves
C‘: Imaginary Circles
C1: First Imaginary Circle
C2: Second Imaginary Circle
r1: First Predetermined Radius
r2: Second Predetermined Radius
OA, OB: Pair of First Radii
OA’, OB’: Pair of Second Radii
OAB: First Sector
OA’B’: Second Sector
AB, A’B’: Arc Length
? : Predetermined angle
, Claims:1. A machine (100), comprising:
a first member (110), the first member (110) having a plurality of magnets (112); and
a second member assembly (120), wherein the first member (110) being configured to rotate concentrically with reference to with the second member assembly (120), the second member assembly (120) comprising:
a yoke (122), the yoke (122) being provided radially inward from the first member (110); and
a plurality of teeth (124), the plurality of teeth (124) extending radially outward from the yoke (122), each of the teeth (124) comprising a head portion (124A) and a stem portion (124B), the head portion (124A) provided radially inward of the first member (110) and radially outward of the yoke (122), and the stem portion (124B) extending between the yoke (122) and the head portion (124A) such that the stem portion (124B) being configured to have a predetermined profile to receive one or more coils (114).

2. The machine (100) as claimed in claim 1, wherein the predetermined profile includes an arcuate shaped profile when the stem portion (124B) of the teeth (124) being viewed in a side direction of the machine (100).

3. The machine (100) as claimed in claim 2, wherein the arcuate shaped profile of the stem portion (124B) being defined by two or more imaginary circles (C’) to provide predetermined arc length for the stem portion (124B).

4. The machine (100) as claimed in claim 3, wherein the imaginary circles (C’) include a first imaginary circle (C1) and a second imaginary circle (C2), the first imaginary circle (C1) and the second imaginary circle (C2) being concentric and having a first predetermined radius (r1) and a second predetermined radius (r2) respectively.

5. The machine (100) as claimed in claim 4, wherein the first predetermined radius (r1) of the first imaginary circle (C1) is different from the second predetermined radius (r2) of the second imaginary circle (C2) to define at least one geometric parameter of the stem portion (124B) of the machine (100).

6. The machine (100) as claimed in claim 5, wherein a first sector (OAB) of a predetermined angle (?) being formed by a pair of first radii (OA and OB), and a second sector (OA`B`) of the predetermined angle (?) being formed by a pair of second radii (OA’ and OB’), the predetermined angle (?) of the first sector (OAB) being same as the second sector (OA`B`).

7. The machine (100) as claimed in claim 6, wherein an arc length (AB) defined in the first sector (OAB) and an arc length (A’B’) defined in the second sector (OA`B`) being different from each other.

8. The machine (100) as claimed in claim 7, wherein a portion of arc length (AB) between the yoke (122) and the head portion (124A), and a portion of arc length (A’B’) between the yoke (122) and the head portion (124A), determines a second geometric parameter of the stem portion (124B) of the teeth (124).

9. The machine (100) as claimed in claim 1, wherein the stem portion (124B) of the teeth (124) comprises a plurality of grooves (130) provided on an outer face of the stem portion (124B) of the teeth (124), the plurality of grooves (130) being configured to receive the one or more coils (114).

10. The machine (100) as claimed in claim 9, wherein the grooves (130) being configured to receive the one or more coils (114) of predetermined profile to provide improved fill factor.

11. The machine (100) as claimed in claim 10, wherein the predetermined profile of the one or more coils (114) includes a polygon or round shaped.

12. The machine (100) as claimed in claim 6, wherein an angle of curvature of the stem portion (124B) is a second predetermined angle, the second predetermined angle being greater than the predetermined angle (?), thereby being capable of accommodating a higher number of windings of the one or more coils (114).

13. The machine (100) as claimed in claim 1, wherein the machine (100) is an integrated starter generator machine for a motor vehicle.