FIELD OF THE INVENTION
The invention relates to motor / generator and in particular to construction of a magnet
holding structure a motor / generator.
BACKGROUND OF THE INVENTION
Motors/generators commonly used for converting electrical energy into mechanical energy
and vice versa generally comprise a magnet holding structure and a coil holding structure.
A conventional construction of the magnet holding structure includes a yoke (which is
generally a cylindrical member) having plurality of magnet accommodating gaps and
plurality of permanent magnets that are accommodated within the plurality of magnet
accommodating gaps.
In another conventional construction, the magnet holding structure includes a yoke (which is
generally a cylindrical member) and a plurality of permanent magnets fixedly connected to
the yoke by an adhesive.
Yet another conventional construction, the magnet holding structure includes a frame; an
annular iron core combined integrally with the frame; and a plurality of insertion holes
formed in the core so that the permanent magnets are inserted in the insertion holes
respectively, wherein the frame, the core and the permanent magnets are combined integrally
with one another by a synthetic resin. Each insertion hole includes a magnet disposing
portion in which the permanent magnet is disposed, a space portion located in at least one of
circumferential both ends of each permanent magnet disposed in the magnet disposing
portion, and a positioning portion positioning each permanent magnet in the magnet
disposing portion, and the molten synthetic resin is poured into the space portion.
In yet another conventional construction, the magnet holding structure includes a frame made
of a resin and having a cylindrical yoke mounting portion, a base covering one end side of the
yoke mounting portion, and a shaft supporting portion located at a center of the base. The
yoke mounting portion, the base and the shaft supporting portion are formed integrally with
the frame; and a plurality of magnets are provided on the yoke mounting portion.
It has however been felt that the aforesaid mechanisms of forming the magnet holding
structure are riddled with one or more disadvantages as are generally known to a person
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skilled in the art. Thus, an object of the present invention is to provide a magnet holding
structure that addresses the aforesaid disadvantages.
SUMMARY OF THE INVENTION
This summary is provided to introduce a selection of concepts in a simplified format that is
further described in the detailed description of the invention. This summary is neither
intended to identify key or essential inventive concepts of the invention and nor is it intended
for determining the scope of the invention.
Accordingly, the present invention provides a magnet holding structure of a motor /
generator. The magnet holding structure comprises a yoke member defining a closed end and
an open end. The magnet holding structure further comprises a cylindrical structure defining
a first end and an opposing second end, the cylindrical structure comprising a plurality of
permanent magnets and plurality of magnet holding members placed alternatively. In an
embodiment, the cylindrical structure is located within the yoke member. In an embodiment,
the first end of the cylindrical structure is coupled to the closed end of the yoke member via a
set of first connecting members.
To further clarify advantages and features of the present invention, a more particular
description of the invention will be rendered by reference to specific embodiments thereof,
which is illustrated in the appended drawings. It is to be appreciated that these drawings
depict only typical embodiments of the invention and are therefore not to be considered
limiting of its scope. The invention will be described and explained with additional
specificity and detail with the accompanying drawings.
Brief Description of Figures:
These and other features, aspects, and advantages of the present invention will become better
understood when the following detailed description is read with reference to the
accompanying drawings in which like characters represent like parts throughout the
drawings, wherein:
FIGURE 1 illustrates a perspective view of a motor / generator constructed in accordance
with an embodiment of the invention;
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FIGURE 2 illustrates a top view of the motor / generator constructed in accordance with an
embodiment of the invention;
FIGURE 3 illustrates a close-up view of the magnet holding structure constructed in
accordance with an embodiment of the invention;
FIGURE 4 illustrates an exploded view of the magnet holding structure constructed in
accordance with an embodiment of the invention;
FIGURE 5 illustrates a close-up view of the permanent magnet in accordance with an
embodiment of the invention;
FIGURE 6 illustrates a close-up view of a magnet holding member in accordance with an
embodiment of the invention; and
FIGURE 7 illustrates a close-up view of a magnet holding means in accordance with an
alternative embodiment of the invention.
Further, skilled artisans will appreciate that elements in the drawings are illustrated for
simplicity and may not have been necessarily been drawn to scale. For example, the
construction of the device, one or more components of the device may have been represented
in the drawings by conventional symbols, and the drawings may show only those specific
details that are pertinent to understanding the embodiments of the present invention so as not
to obscure the drawings with details that will be readily apparent to those of ordinary skill in
the art having benefit of the description herein.
Detailed Description:
For the purpose of promoting an understanding of the principles of the invention, reference
will now be made to the embodiment illustrated in the drawings and specific language will be
used to describe the same. It will nevertheless be understood that no limitation of the scope of
the invention is thereby intended, such alterations and further modifications in the illustrated
system, and such further applications of the principles of the invention as illustrated therein
being contemplated as would normally occur to one skilled in the art to which the invention
relates.
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It will be understood by those skilled in the art that the foregoing general description and the
following detailed description are exemplary and explanatory of the invention and are not
intended to be restrictive thereof.
Reference throughout this specification to “an aspect”, “another aspect” or similar language
means that a particular feature, structure, or characteristic described in connection with the
embodiment is included in at least one embodiment of the present invention. Thus,
appearances of the phrase “in an embodiment”, “in another embodiment” and similar
language throughout this specification may, but do not necessarily, all refer to the same
embodiment.
The terms "comprises", "comprising", or any other variations thereof, are intended to cover a
non-exclusive inclusion, such that a process or method that comprises a list of steps does not
include only those steps but may include other steps not expressly listed or inherent to such
process or method. Similarly, one or more devices or sub-systems or elements or structures or
components proceeded by "comprises a" does not, without more constraints, preclude the
existence of other devices or other sub-systems or other elements or other structures or other
components or additional devices or additional sub-systems or additional elements or
additional structures or additional components.
Unless otherwise defined, all technical and scientific terms used herein have the same
meaning as commonly understood by one of ordinary skill in the art to which this invention
belongs. The system, methods, and examples provided herein are illustrative only and not
intended to be limiting.
Embodiments of the present invention will be described below in detail with reference to the
accompanying drawings.
Now referring to Figures 1 and 2, there is illustrated a perspective view and a top view of a
motor / generator (10) constructed in accordance with the embodiments of the invention. The
motor / generator (10) comprises magnet holding structure (12) and a coil holding structure
(68). The coil holding structure (68) is placed at about a central location of the magnet
holding structure (12). In an embodiment of the invention, the motor / generator (10) is of an
outer rotor type i.e. the coil holding structure (68) is retained in a stationary state while the
magnet holding structure (12) is allowed to rotate with respect to the coil holding structure
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(68). Alternatively, the motor / generator (10) is of an inner rotor type i.e. magnet holding
structure (12) is retained in a stationary state while the coil holding structure (68) is allowed
to rotate with respect to the magnet holding structure (12)..
As can be best seen from Figures 2 and 3, the magnet holding structure (12) comprises a yoke
member (14) defining a closed end (16) and an open end (18) and a cylindrical structure (20)
located within and coupled to the yoke member (14).
As best seen from Figures 2, 3 and 4, the cylindrical structure (20) comprises of plurality of
permanent magnets (22) and plurality of magnet holding members (24) placed alternatively.
As best seen from Figure 4, the cylindrical structure (20) defines a first end (28) and a second
end (32). The second end (32) is located opposite to first end (28).
The cylindrical structure (20) is coupled to the yoke member (14) and in particular, to the
closed end (16) of the yoke member (14) via a set of first connecting members (26). In an
embodiment of the invention, the first end (28) of the cylindrical structure (20) is coupled to
the closed end (16) of the yoke member (14) via the set of first connecting members (26).
The magnet holding structure (12) may optionally comprise a ring member (34) which is
joined to the second end (32) of the cylindrical structure (20). In particular, the ring member
(34) is joined to the second end (32) of the cylindrical structure (20) via a set of second
connecting members (30).
In an embodiment of the invention, the set of first connecting members (26) may include a
male projecting portion (70) and a female receiving portion (36) that co-operate with each
other so as to couple the cylindrical structure (20) to the yoke member (14).
In an embodiment of the invention, the male projecting portion (70) may be formed on the
first end (28) of the cylindrical structure (20) and the female receiving portion (36) may be
formed in the yoke member (14). Although not illustrated, in an alternative construction, the
male projecting portion (70) may be formed on the yoke member (14) and the female
receiving portion (36) may be formed on the first end (28) of the cylindrical structure (20).
In an alternative embodiment of the invention, the set of first connecting members (26) may
include fastening means adapted to couple the cylindrical structure (20) to the yoke member
(14).
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In an embodiment of the invention, the set of second connecting members (30) may include a
male projecting portion (72) (not visible) and a female receiving portion (74) that co-operate
with each other so as to couple the cylindrical structure (20) to the ring member (34).
In an embodiment of the invention, the male projecting portion (72) (not visible) may be
formed on the second side (32) of the cylindrical structure (20) and the female receiving
portion (74) may be formed in the ring member (34). Although not illustrated, in an
alternative construction, the male projecting portion (72) (not visible) may be formed on the
ring member (34) and the female receiving portion (74) may be formed on the second side
(32) of the cylindrical structure (20).
In an alternative embodiment of the invention, the set of second connecting members may
include fastening means adapted to couple the cylindrical structure (20) to the ring member
(34).
In an embodiment of the invention, the yoke member (14) comprises a housing (62) having
an inwardly projecting stub end (64), and an end cap (66) cooperating with the stub end (64),
the end cap (66) defining the closed end (16) of the yoke member (14).
As best seen from Figure 5, each of the plurality of permanent magnets (22) comprise curved
inner and outer walls (38, 40), a pair of magnet side walls (42, 44) extending between the
inner and the outer walls (38, 40), and a pair of axially extending end faces (46, 48). In
particular, the pair of magnet side walls (42, 44) taper away from each other in a radial
direction. In an embodiment of the invention, the permanent magnet (22) is provided with
first male projecting portion (70) on the first axially extending end face (46). It may be noted
that the permanent magnet (22) may also be provided with second male projecting portion
(72) on the second axially extending end face (48).
As best seen from Figure 6, each of the plurality of magnet holding member(24) comprises an
inner and an outer wall (50, 52), a pair of holder side walls (54, 56) extending between the
inner and the outer walls (50, 52), and a pair of axially extending end faces (58, 60). In
particular, the pair of holder side walls (54, 56) converge towards each other in a radial
direction. In an embodiment of the invention, the magnet holding member is provided with
first male projecting portion (70) on the first axially extending end face (58). It may be noted
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that the magnet holding member may also be provided with second male projecting portion
(72) (not visible) on the second axially extending end face (60).
It is also possible that the magnet holding members (24) are provided with the first male
projecting portion (70) on the first axially extending end face (58) and that the permanent
magnets (22) are provided with the second male projecting portion (72) (not visible) on the
second axially extending end face (48).
It is also possible that the permanent magnets (22) are provided with the first male projecting
portion (70) on the first axially extending end face (46) and that the magnet holding members
(24) are provided with the second male projecting portion (72) (not visible) on the second
axially extending end face (60).
In an embodiment of the invention, the magnet holding member has a width “Wmhm” as
measured in the radial direction. In another embodiment of the invention, the permanent
magnet has a width “Wpm” in the radial direction. In a preferred embodiment of the invention,
the width of the magnet holding member “Wmhm” is greater than the width of the permanent
magnet “Wpm”. But some cases Wmhm may be equal or lower than Wpm as per requirement.
In an embodiment of the invention as best seen from Figure 7, each of the plurality of magnet
holding member (24) comprises an inner and an outer wall (50, 52), a pair of holder side
walls (54, 56) extending between the inner and the outer walls (50, 52), and a pair of axially
extending end faces (58, 60). Each holder side wall (54, 56) comprises of two segments (S1,
S1’, S2 and S2’). The pair of first segments (S1 and S1’) extends substantially perpendicular
from the outer wall (52) terminate at about an intermediate portion (not numbered). The pair
of second segments (S2 and S2’) extends from the intermediate portion and terminate at the
inner wall (50). The pair of second segments (S2 and S2’) converge towards each other in a
radial direction.
In an embodiment of the invention, the permanent magnets can be made of any of
conventional material such as Ferrite, Ndfeb while the magnet holder members can be made
of a soft magnetic material such as Electrical steel. In an embodiment of the invention, the
permanent magnets may be magnetized along the circumferential direction as shown in
Figure 5. As shown in Figure 2, the permanent magnets may be placed such that the North
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Pole of a first magnet is proximate to the South Pole of a second magnet which is located
adjacent thereto.
In an embodiment of the invention, the coil holding structure (68) may be provided with
provided with laminated core on which coil may be wound. In an embodiment of the
invention, the coil holding structure (68) may be provided with 1-phase coil winding or 2-
phase coil winding or 3-phase coil winding.
In an embodiment of the invention, a resin material may be additionally used to couple the
cylindrical structure (20) and the yoke member (14).
The magnet holding structure as described above allows for formation of small and lightweight
motors. The magnet holding structure (12) comprises lesser parts and is therefore easy
to manufacture.
The drawings the foregoing descriptions give examples of embodiments. Those skilled in the
art will appreciate that one or more of the described elements may well be combined into a
single functional element. Alternatively certain elements may be split into multiple functional
elements. Elements from one embodiment may be added to another embodiment. For
example, orders of process described herein may be changed and are not limited to the
manner described herein. Moreover the actions of any flow diagram need not be implemented
in the order shown; nor do all of the acts necessarily need to be performed. In addition, those
acts that are not dependent on other acts may be performed in parallel with the other acts. The
scope of embodiments is by no means limited by these specific examples. The scope of
embodiments is at least as broad as the following claims.

WE CLAIM:
1. A magnet holding structure (12) of a motor / generator (10), comprising:
a yoke member (14) defining a closed end (16) and an open end (18); and
a cylindrical structure (20) comprising of plurality of permanent magnets (22)
and plurality of magnet holding members (24) placed alternatively, the
cylindrical structure (20) being located within the yoke member (14), the
cylindrical structure (20) comprising a first end (28) and a second end (32)
opposite the first end (30), the first end (28)of the cylindrical structure (20)
being coupled to the closed end (16) of the yoke member (14) via a set of first
connecting members (26).
2. The magnet holding structure as claimed in claim 1, wherein the set of first
connecting members (26) includes at least one of:
a male projecting portion (70) formed on the first end (28) of the cylindrical
structure (20) and a female receiving portion (36) formed in the yoke member
(14), the female receiving portion (36) being adapted to co-operate with male
projecting portion (70) so as to couple the cylindrical structure (20) to the
yoke member (14);
a male projecting portion (70) formed on the yoke member (14) and a female
receiving portion (36) formed on the first end (28) of the cylindrical structure
(20), the female receiving portion (36) being adapted to co-operate with male
projecting portion (70) so as to couple the cylindrical structure (20) to the
yoke member (14); or
at least one fastening means adapted to couple the cylindrical structure (20) to
the yoke member (14).
3. The magnet holding structure as claimed in claim 1, comprising a ring member (34)
joined to the second end (32) of the cylindrical structure (20) via a set of second
connecting members (30).
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4. The magnet holding structure as claimed in claim 3, wherein the set of second
connecting members (30) includes at least one of:
a male projecting portion (72) formed on the second end (32) of the cylindrical
structure (20) and a female receiving portion (74) formed in the ring member,
the female receiving portion (74) being adapted to co-operate with male
projecting portion (72) so as to couple the cylindrical structure (20) to the ring
member (34);
a male projecting portion (72) formed on the ring member (34) and a female
receiving portion (74) formed on the second end (32) of the cylindrical
structure, the female receiving portion (74) being adapted to co-operate with
male projecting portion (72) so as to couple the cylindrical structure (20) to
the ring member (34); or
at least one fastening means adapted to couple the cylindrical structure (20) to
the ring member (34).
5. The magnet holding structure as claimed in claim 1, wherein the each of the plurality
of permanent magnets (22) comprise curved inner and outer walls (38, 40), a pair of
magnet side walls (42, 44) extending between the inner and the outer walls (38, 40),
and a pair of axially extending end faces (46, 48).
6. The magnet holding structure as claimed in claim 5, wherein the pair of magnet side
walls (42, 42) taper away from each other in a radial direction.
7. The magnet holding structure as claimed in claim 1, wherein each of the plurality of
magnet holding member (24) comprises an inner and an outer wall (50, 52), a pair of
holder side walls (54, 56) extending between the inner and the outer walls (50, 52),
and a pair of axially extending end faces (58, 60).
8. The magnet holding structure as claimed in claim 7, wherein the pair of holder side
walls (54, 56) converge towards each other in a radial direction.
9. The magnet holding structure as claimed in claim 1, wherein the yoke member (14)
comprises a housing (62) having an inwardly projecting stub end (64), and an end cap
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(66) cooperating with the stub end (64), the end cap defining the closed end (16) of
the yoke member (14).
10. The magnet holding structure as claimed in claim 1, wherein a width of the magnet
holding member, as measured in the radial direction, is greater than a width of the
permanent magnet.
11. A motor / generator (10) comprising:
a coil holding structure (68); and
a magnet holding structure (12), the magnet holding structure (12)comprising:
a yoke member (14) defining a closed end (16) and an open end (18); and
a cylindrical structure (20) comprising of plurality of permanent magnets (22)
and plurality of magnet holding members(24) placed alternatively, the
cylindrical structure (20) being located within the yoke member (14), the
cylindrical structure (20) comprising a first end (28) and a second end (32)
opposite the first end (30), the first end (28) of the cylindrical structure (20)
being coupled to the closed end (16) of the yoke member (14) via a set of first
connecting members (26) .