U.S. patent application number 14/424071 was filed with the patent office on 2015-08-13 for rotor with magnet pattern.
The applicant listed for this patent is ALBUS Technologies Ltd.. Invention is credited to Alexander Sromin.
Application Number | 20150229194 14/424071 |
Document ID | / |
Family ID | 50182609 |
Filed Date | 2015-08-13 |
United States Patent
Application |
20150229194 |
Kind Code |
A1 |
Sromin; Alexander |
August 13, 2015 |
ROTOR WITH MAGNET PATTERN
Abstract
Planar rotor designs for axial air-gap electric machines are
presented. Some embodiments comprise rotors each of whose magnetic
poles comprise a pair of permanent magnets each magnetized in an
orientation of about 45.degree. to the direction of the rotor axis.
In some embodiments, axial components of the magnetization of each
pair of magnets are co-directional, and tangential components of
the magnetization of each pair of magnets are opposite.
Inventors: |
Sromin; Alexander; (Ashdod,
IL) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
ALBUS Technologies Ltd. |
Ashdod |
|
IL |
|
|
Family ID: |
50182609 |
Appl. No.: |
14/424071 |
Filed: |
August 27, 2013 |
PCT Filed: |
August 27, 2013 |
PCT NO: |
PCT/IL2013/050728 |
371 Date: |
February 26, 2015 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61693375 |
Aug 27, 2012 |
|
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61773295 |
Mar 6, 2013 |
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Current U.S.
Class: |
310/156.07 ;
310/156.32; 310/156.37 |
Current CPC
Class: |
H02K 21/24 20130101;
H02K 1/32 20130101; H02K 1/2793 20130101; H02K 16/02 20130101; H02K
3/28 20130101 |
International
Class: |
H02K 16/02 20060101
H02K016/02; H02K 1/27 20060101 H02K001/27 |
Claims
1-5. (canceled)
6. A rotor for an axial air-gap electric machine having a
rotational axis, said rotor comprising alternating north and south
magnetic poles, each of said north and south poles being generated
by a pair of permanent magnets, wherein axial components of the
magnetization of said paired magnets are co-directional, and
tangential components of the magnetization of said paired magnets
are opposite.
7. The rotor of claim 6, comprising first and second sets of magnet
pairs, magnet pairs of said first set having tangential
magnetization components directed towards each other, magnet pairs
of said second set having tangential magnetization components
directed away from each other, and wherein pairs of said first set
alternate with pairs of said second set around said rotor.
8. (canceled)
9. The rotor of claim 6, wherein said pairs of magnets are
magnetized with an orientation of between 30.degree. and 60.degree.
to the rotational axis of the rotor.
10. (canceled)
11. The rotor of claim 6, wherein additional magnet elements having
a tangential magnetization component are interposed between said
south and north poles.
12. The rotor of claim 11, wherein said additional magnet elements
are so oriented that their tangential magnetization component
points away from a magnet pair generating a south pole and towards
a magnet pair generating a north pole.
13-15. (canceled)
16. The rotor of claim 6 wherein at least some of said pairs of
magnets are butt-jointed.
17. The rotor of claim 6, wherein at least some of said pairs of
magnets are spaced away from adjacent pairs of magnets.
18-19. (canceled)
20. The rotor of claim 6, wherein at least some of said magnet
pairs comprise permanent magnets which are spaced apart so that
they do not touch each other.
21-22. (canceled)
23. The rotor of claim 6, further comprising a soft magnetic
yoke.
24. The rotor of claim 23, wherein said yoke comprises ribs which
separate each pair of magnets from adjacent pairs of magnets.
25. The rotor of claim 23, wherein said yoke comprises ribs which
separate each permanent magnet from adjacent permanent magnets.
26. The rotor of claim 23, wherein said yoke comprise radial
slot-like openings.
27. The rotor of claim 26, wherein at least some of said magnets
have a face which is supported by said yoke and which is also least
partially exposed to air through one of said openings.
28. The rotor of claim 6, wherein said magnets comprise a first
layer, and the rotor further comprising a second layer adjacent to
said first layer, said second layer comprising axially magnetized
permanent magnets.
29. The rotor of claim 28, wherein each of said axially magnetized
permanent magnets of said second layer has a magnetic orientation
opposite that of the axially magnetized permanent magnets which are
adjacent to it on said second layer.
30. The rotor of claim 28, wherein magnets of each of said pairs of
magnets are butt-jointed to each other and to one of said axially
magnetized magnet pieces.
31. An axial air-gap electric machine comprising the rotor of claim
6.
32. The machine of claim 31, comprising a rotor assembly which
comprises two of said rotors spaced-apart, creating between them a
flux which makes closure through adjacent pole sections of
counter-directed axial magnetic flux.
33. The machine of claim 32, comprising a stator positioned between
said rotors.
34. The machine of claim 32, further comprising at least one
discoid rotor comprising axially magnetized permanent magnets
forming a heteropolar magnetic system having a number of poles
equal to the number of poles of each of said spaced-apart
rotors.
35-37. (canceled)
Description
RELATED APPLICATIONS
[0001] This application claims the priority and benefit under 35
USC 119(e) of US Provisional Patent Applications 61/773,295 filed 6
Mar. 2013 and 61/693,375 filed 27 Aug. 2012, the disclosures of
which are incorporated herein by reference.
FIELD AND BACKGROUND OF THE INVENTION
[0002] The present invention, in some embodiments thereof, relates
to a rotor for an electric machine such as an electric motor or
generator, and, more particularly, but not exclusively, to patterns
for magnetic elements of a planar rotor for an axial air-gap
electric machine.
[0003] As an aid to understanding the present invention, several
examples of known designs for planar rotors of axial air-gap
machines are presented, for purposes of comparison, in the
accompanying figures, and are discussed herein. As will be seen in
that discussion, some of these designs presented may be relatively
inefficient in the use of space available for a planar rotor, as
compared to some embodiments of the present invention disclosed
herein. Additionally, some of these known designs may be more
expensive or more difficult to build, as compared to some
embodiments of the present invention disclosed herein.
[0004] Note is taken of the following documents describing
inventions in this field:
[0005] U.S. Pat. No. 5,783,885 to Richard F. Post, for "Self
Adjusting Magnetic Bearing Systems".
[0006] U.S. Pat. No. 7,084,548 to Christopher W. Gabrys, for "Low
Cost High Speed Electrical Machine".
[0007] U.S. Patent Application Publication No. US2005/0236918 by
Hugo H. van den Bergh et al., for "Rotary Disk Energy Storage and
Pulse Power Supply".
[0008] U.S. Patent Application Publication No. US2010/0253173 by
Koji Miyata et al., for "Axial Gap Type Coreless Rotating
Machine".
[0009] U.S. Patent Application Publication No. US2011/0024567 by
Mark Blackwelder et al., for "Electrical Power Generation Apparatus
for Contra-Rotating Open-Rotor Aircraft Propulsion System".
SUMMARY OF THE INVENTION
[0010] Some embodiments of the invention pertain to an electrical
machine such as an electric motor or generator whose rotor is a
planar unit. Designs presented below may provide improved
optimization in the use of magnet material incorporated into the
rotors, as compared to previously known designs. The designs may
also be advantageous in that they may be more simple than some
prior art designs, since some embodiments require only two types of
magnetic pieces whereas some comparably efficient prior art designs
require manufacture and assembly of a larger number of types of
magnetic pieces, which may make those known designs more difficult
and expensive to manufacture.
[0011] According to an aspect of some embodiments of the present
invention there is provided a rotor for an axial air-gap electric
machine comprising alternating north and south magnetic poles, each
of the poles being generated by a pair of permanent magnets.
[0012] According to some embodiments of the invention, for each of
the pairs of permanent magnets, axial components of the
magnetization of the magnets are co-directional, and tangential
components of the magnetization of the paired magnets are opposite
each other.
[0013] According to some embodiments of the invention, the rotor
comprises first and second sets of magnet pairs, magnet pairs of
the first set having tangential magnetization components directed
towards each other, magnets of the second set having tangential
magnetization components directed away from each other, and wherein
pairs of the first set alternate with pairs of the second set
around the rotor.
[0014] According to some embodiments of the invention, the pairs of
magnets are magnetized with an orientation of about 45.degree. to
the rotational axis of the rotor.
[0015] According to some embodiments of the invention, the pairs of
magnets are magnetized with an orientation of between 30.degree.
and 60.degree. to the rotational axis of the rotor.
[0016] According to an aspect of some embodiments of the present
invention there is provided a rotor for an axial air-gap electric
machine having a rotational axis, the rotor comprising alternating
north and south magnetic poles, each of the north and south poles
being generated by a pair of permanent magnets, wherein axial
components of the magnetization of the paired magnets are
co-directional, and tangential components of the magnetization of
the paired magnets are opposite.
[0017] According to some embodiments of the invention, the rotor
comprises first and second sets of magnet pairs, magnet pairs of
the first set having tangential magnetization components directed
towards each other, magnet pairs of the second set having
tangential magnetization components directed away from each other,
and wherein pairs of the first set alternate with pairs of the
second set around the rotor.
[0018] According to some embodiments of the invention, the pairs of
magnets are magnetized with an orientation of about 45.degree. to
the rotational axis of the rotor.
[0019] According to some embodiments of the invention, the pairs of
magnets are magnetized with an orientation of between 30.degree.
and 60.degree. to the rotational axis of the rotor.
[0020] According to some embodiments of the invention, the pairs of
magnets are magnetized with an orientation of between 15.degree.
and 75.degree. to the rotational axis of the rotor.
[0021] According to some embodiments of the invention, additional
magnet elements having a tangential magnetization component are
interposed between the south and north poles.
[0022] According to some embodiments of the invention, the
additional magnet elements are so oriented that their tangential
magnetization component points away from a magnet pair generating a
south pole and towards a magnet pair generating a north pole.
[0023] According to some embodiments of the invention, the
additional magnetic elements interposed between the south and north
poles alternate between a first set of additional magnetic elements
having a tangential magnetic orientation in a first direction, one
of clockwise and counterclockwise, and a second set of additional
magnetic elements having a tangential magnetic orientation in a
second direction opposite the first direction.
[0024] According to some embodiments of the invention, each of the
additional magnetic elements is so oriented that the tangential
magnetic orientation of each of the additional magnetic elements is
away from a south pole and towards a north pole.
[0025] According to some embodiments of the invention, the rotor is
shaped as a disk.
[0026] According to some embodiments of the invention, at least
some of the pairs of magnets are butt-jointed.
[0027] According to some embodiments of the invention, at least
some of the pairs of magnets are spaced away from adjacent pairs of
magnets.
[0028] According to some embodiments of the invention, the rotor
comprises a space between each of the pairs of magnets.
[0029] According to some embodiments of the invention, the magnet
pairs comprise permanent magnets butt-jointed to each other.
[0030] According to some embodiments of the invention, at least
some of the magnet pairs comprise permanent magnets which are
spaced apart so that they do not touch each other.
[0031] According to some embodiments of the invention, all of the
pairs of magnets are butt-jointed and all of the permanent magnet
elements are of a same size and shape.
[0032] According to some embodiments of the invention, at least
some of the pairs of magnets are butt-jointed and comprise
permanent magnet elements of a same size and shape.
[0033] According to some embodiments of the invention, the rotor
further comprises a soft magnetic yoke.
[0034] According to some embodiments of the invention, the yoke
comprises ribs which separate each pair of magnets from adjacent
pairs of magnets.
[0035] According to some embodiments of the invention, the yoke
comprises ribs which separate each permanent magnet from adjacent
permanent magnets.
[0036] According to some embodiments of the invention, the yoke
comprise radial slot-like openings.
[0037] According to some embodiments of the invention, at least
some of the magnets have a face which is supported by the yoke and
which is also least partially exposed to air through one of the
openings.
[0038] According to some embodiments of the invention, the rotor
comprises a first layer, wherein alternating north and south
magnetic poles are each generated by a pair of permanent magnets
wherein axial components of the magnetization of said paired
magnets are co-directional, and tangential components of the
magnetization of said paired magnets are opposite, and the rotor
further comprises a second layer adjacent to the first layer, the
second layer comprising axially magnetized permanent magnets.
[0039] According to some embodiments of the invention, each of the
axially magnetized permanent magnets of the second layer has a
magnetic orientation opposite that of the axially magnetized
permanent magnets which are adjacent to it on the second layer.
[0040] According to some embodiments of the invention, magnets of
each of the pairs of magnets are but-jointed to each other and to
one of the axially magnetized magnet pieces.
[0041] According to an aspect of some embodiments of the present
invention there is provided an axial air-gap electric machine
comprising a rotor having a rotational axis, the rotor comprising
alternating north and south magnetic poles, each of the north and
south poles being generated by a pair of permanent magnets, wherein
axial components of the magnetization of the paired magnets are
co-directional, and tangential components of the magnetization of
the paired magnets are opposite.
[0042] According to some embodiments of the invention, the machine
comprises a rotor assembly which comprises two spaced-apart rotors,
each comprising alternating north and south magnetic poles, each of
said north and south poles being generated by a pair of permanent
magnets, wherein axial components of the magnetization of said
paired magnets are co-directional, and tangential components of the
magnetization of said paired magnets are opposite, the spaced-apart
rotors creating between them a flux which makes closure through
adjacent pole sections of counter-directed axial magnetic flux.
[0043] According to some embodiments of the invention, the machine
comprises a stator positioned between the rotors.
[0044] According to some embodiments of the invention, the machine
further comprises at least one discoid rotor comprising axially
magnetized permanent magnets forming a heteropolar magnetic system
having a number of poles equal to the number of poles of each of
the spaced-apart end rotors.
[0045] According to an aspect of some embodiments of the present
invention there is provided a rotor for an axial air-gap electric
machine providing more than 90.degree. of the amount of flux
available from a Halbach system of comparable size and weight and
comprising only two types of permanent magnet components.
[0046] According to some embodiments of the invention, the two
types of permanent magnet components are of same shape and differ
in their magnetic orientations.
[0047] According to an aspect of some embodiments of the present
invention there is provided a method of constructing a rotor for an
axial air-gap electric machine, comprising:
[0048] a) constructing first and second sets of pairs of permanent
magnets; and
[0049] b) constructing a discoidal assembly of the pairs of magnets
in such a way that a pair of magnets of the first set alternates
with a pair of magnets of the second set around the discoidal
assembly, wherein
[0050] i) magnet pairs of both the first and second sets so
positioned and oriented that axial components of magnetizations of
each pair are co-directional;
[0051] ii) magnet pairs of the first set are so positioned and
oriented that tangential components of their magnetization are
directed towards each other; and
[0052] iii) magnet pairs of the second set are so positioned and
oriented tangential components their magnetization are directed
away from each other.
[0053] Unless otherwise defined, all technical and/or scientific
terms used herein have the same meaning as commonly understood by
one of ordinary skill in the art to which the invention pertains.
Although methods and materials similar or equivalent to those
described herein can be used in the practice or testing of
embodiments of the invention, exemplary methods and/or materials
are described below. In case of conflict, the patent specification,
including definitions, will control. In addition, the materials,
methods, and examples are illustrative only and are not intended to
be necessarily limiting.
BRIEF DESCRIPTION OF THE DRAWINGS
[0054] Some embodiments of the invention are herein described, by
way of example only, with reference to the accompanying drawings.
With specific reference now to the drawings in detail, it is
stressed that the particulars shown are by way of example and for
purposes of illustrative discussion of embodiments of the
invention. In this regard, the description taken with the drawings
makes apparent to those skilled in the art how embodiments of the
invention may be practiced.
[0055] In the drawings:
[0056] FIG. 1 presents an isometric view of a rotor with separated
permanent magnet pieces magnetized through the thickness and glued
on a yoke disk face, and also a cross-section of an electric
machine utilizing the rotor shown in the isometric view, according
to a method of prior art;
[0057] FIG. 2 presents a cross-section and a top view of a rotor
with stacked permanent magnet pieces magnetized through the
thickness and secured on a discoidal yoke, according to a method of
prior art;
[0058] FIG. 3 is an isometric view of a rotor, including a detail
section which shows a classic design Halbach design, according to a
method of prior art;
[0059] FIG. 4 is an isometric view of two rotors, mechanically
connected and facing each other, a Halbach design according to a
method of prior art;
[0060] FIG. 5 presents an additional view of two Halbach rotors
facing each other, and further presents a cross-section of an
electric machine utilizing such rotors, according to a method of
prior art;
[0061] FIG. 6 presents side and top views of a yokeless rotor with
axially magnetized permanent magnet sectors and interposed soft
magnetic sectors, according to a method of prior art;
[0062] FIG. 7 presents a top view and a detailed segment of an
isometric view of a yokeless rotor with alternating axially and
tangentially magnetized permanent magnet sectors, according to a
method of prior art;
[0063] FIG. 8A is an exploded isometric view of a rotor with a
planar yoke, according to some embodiments of the present
invention;
[0064] FIG. 8B is an isometric view of the rotor of FIG. 8A, and
comprises an insert showing a more detailed view of a portion of
that rotor, according to some embodiments of the present
invention;
[0065] FIG. 9 is an isometric view with a detailed fragment of a
rotor with a planar yoke wherein each pole is made from 2
butt-jointed magnet pieces each magnetized by about 45 degrees to
the axis and the poles are distanced from each other, according to
some embodiments of the present invention;
[0066] FIG. 10A is an exploded isometric view of a rotor with a
ribbed yoke in which each pole is made from 2 butt-jointed magnet
pieces each magnetized by about 45 degrees to the axis and the
poles are distanced from each other, according to some embodiments
of the invention;
[0067] FIG. 10B is an isometric view of the rotor of FIG. 10A, and
comprises an insert showing a more detailed view of a portion of
that rotor, according to some embodiments of the present
invention;
[0068] FIG. 11A is an exploded isometric view of a rotor with a
ribbed yoke according to some embodiments of the invention where
each pole is made from 2 distanced magnet pieces each magnetized by
about 45 degrees to the axis and the poles are distanced from each
other, according to some embodiments of the invention;
[0069] FIG. 11B is an isometric view of the rotor disclosed in FIG.
11A, and comprises an insert showing a more detailed view of a
portion of that rotor, according to some embodiments of the
invention;
[0070] FIG. 12A is an exploded isometric view of a rotor without
yoke wherein each pole is made from 2 butt-jointed magnet pieces
each magnetized by about 45 degrees to the axis, the poles are
distanced from each other and tangentially magnetized sectors are
interposed between them, according to some embodiments of the
invention;
[0071] FIG. 12B is an isometric view with a detailed fragment of
the rotor disclosed in FIG. 12A, according to some embodiments of
the invention;
[0072] FIG. 13A is an exploded isometric view of a rotor with a
planar yoke in which each pole is made from two layers, a first
layer as disclosed in FIG. 6A, and a second layer which comprises
butt-jointed alternatingly axially magnetized magnet pieces,
according to some embodiments of the invention;
[0073] FIG. 13B is an isometric view of the rotor disclosed in FIG.
13A, and comprises an insert showing a more detailed view of a
portion of that rotor, according to some embodiments of the
invention;
[0074] FIG. 14 is an isometric view of a rotor assembly useable in
an axial field electric machine, according to some embodiments of
the invention;
[0075] FIG. 15 is an exploded view of an axial field electric motor
utilizing a rotor assembly made according to some embodiments of
the invention;
[0076] FIG. 16A shows fragmentary isometric views of several prior
art designs for which working magnetic flux was approximately
calculated, the calculation/estimation results being shown in FIG.
17;
[0077] FIG. 16B shows fragmentary isometric views of several
designs according to embodiments of the present invention, for
which working magnetic flux was approximately calculated, the
calculation/estimation results being shown in FIG. 17;
[0078] FIG. 17 is a table showing approximate calculated/estimated
working magnetic flux for designs shown in FIGS. 16A and 16B.
[0079] FIG. 18A is an isometric view of a multi-stage modular
axial-flux machine utilizing two rotors according to some
embodiments of the present invention, two conventional axial flux
permanent magnet rotors and three coreless stators, each positioned
between a pair of rotors, according to some embodiments of the
present invention;
[0080] FIG. 18B is a cross sectional view of the axial flux machine
disclosed in FIG. 18A, according to some embodiments of the present
invention;
[0081] FIG. 19 is an isometric view of a conventional axial flux
permanent magnet rotor to be used in an axial flux machine
disclosed in FIG. 18.
DESCRIPTION OF SPECIFIC EMBODIMENTS OF THE INVENTION
[0082] The present invention, in some embodiments thereof, relates
to rotors for electric machines such as an electric motors and/or
generators, and, more particularly, but not exclusively, to
patterns for magnetic elements of planar rotors for axial air-gap
electric machines.
[0083] As used throughout the present disclosure and in the claims
below, the terms "machine" and "electrical machine" are to be
understood to include both electric motors and electric
generators.
Previously Known Designs
[0084] For purposes of better understanding some embodiments of the
present invention, as illustrated in FIGS. 8-19 of the drawings,
reference is first made to the construction and operation of
several known designs for rotors, as illustrated in FIGS. 1-7.
[0085] Attention is first drawn to FIGS. 1 and 2, which show
heteropolar magnet systems of axial flux rotors, according to
methods of prior art. FIG. 1 is adapted from US patent application
2010/0253173 A1 of Koji Miyata et al. FIG. 2 is adapted from U.S.
Pat. No. 7,084,548 B1 to Christopher W. Gabrys Grassman. These
systems, which may be thought of as representative of the genre,
each comprise a plurality of identical permanent magnet pieces
magnetized through the thickness. The magnets are alternatively
secured on a yoke face (usually magnets attached by their N-face
alternate with magnets attached by their S-face, alternating around
the rotor) to build a heteropolar magnetization. With reference the
face of a rotor that will be adjacent to a stator in an electric
machine, (the "working face" herein), each magnet piece engenders a
magnet pole, either a north pole A generating essentially outgoing
axial flux F, or a south pole B generating essentially incoming
axial flux G, and these poles alternate around the rotor. These
magnet pieces are placed annularly on the face of a soft magnetic
yoke E formed as a disc. Yoke E functions as a conductor of the
tangential magnetic flux J between poles A and B.
[0086] The approach taken in systems such as those shown in FIGS. 1
and 2 enable construction based on a plurality of identical
permanent magnet pieces. This fact may significantly simplify
design and construction of the systems, but may be disadvantageous
in that it requires a rather heavy yoke because it is designed to
conduct a rather high interpole magnetic flux. The heavy yoke may
be physically disadvantageous in use and may be awkward in
construction because of its weight and bulk, and may represent a
loss of efficiency because it is a passive part used only to
accomplish closure of the magnetic flux field, and does not
otherwise contribute to the generation of magnetic energy.
[0087] An alternative approach, also known according to methods of
prior art, is shown in FIGS. 3-5. These designs are based on what
is known as a "Halbach" array, wherein each magnet pole (either
north magnet pole A and or south magnet pole B) is built from a
number of sectorial permanent magnet pieces of about the same shape
(eight such pieces are shown in the example in FIG. 3). This method
enables construction of a rotor which comprises only active
magnetic path components which generate magnetic energy, as no yoke
may be needed. Each of the sectorial permanent magnet pieces is
magnetized at an angle which differs from the magnetization angle
of the adjacent piece, e.g. by starting at 0.degree. relative to
the rotor axle (tangent magnetization) and finishing at 180.degree.
(axial magnetization), as may be seen in FIG. 3, where eight pieces
are used to make the 180.degree. transition. For example, the
pieces which constitute a pole A are labeled in the figure as
A1-A8.
[0088] FIG. 4 shows another Halbach implementation, wherein two
mechanically connected Halbach rotors R1 and R2 face each other, as
disclosed in US patent application 2011/024567A1 by Mark J.
Blackwelder et al. FIG. 4 shows each magnet pole section of each
rotor as built from 7 permanent magnet sectors. With reference to
one of the rotors on the figure: [0089] An axially magnetized
sector A11 of half width generates flux G1 (F1); [0090] a sector
A12 magnetized in an orientation .about.30 degrees from the axis
direction generates flux G2 (F2); [0091] a sector A13 magnetized in
an orientation .about.60 degrees from the axis direction generates
flux G3 (F3); [0092] a sector A14 magnetized in an orientation
.about.90 degrees from the axis direction (tangentially and
perpendicular to the axis) generates flux T; [0093] a sector A15
magnetized in an orientation .about.120 degrees with reference to
the axis direction generates flux F3 (G3); [0094] a sector A16
magnetized in an orientation of .about.150 with reference to the
axis direction generates flux F2 (G2); and [0095] An axially
magnetized sector A17 of half width generates flux G1 (F1).
[0096] Since sectors A11 and A17 are identical, there are 6
different sorts of magnet sector pieces. The fluxes
G1-G2-G3-T-F3-F2-F1 from rotor R1 together with fluxes
G1-G2-G3-T-F3-F2-F1 from rotor R2 build a working magnetic flux
.PHI. concentrated in the operating gap .delta. between the rotors
R1-R2.
[0097] A similar configuration is shown in FIG. 5, adapted from
U.S. Patent Application 2005/0236918 A1 of Hugo H. van den Bergh et
al. FIG. 5 shows a detail view of a magnetic system formed by two
mechanically connected Halbach rotors R11-R12 which face each
other. The figure also shows a cross section of an electric machine
utilizing such rotors. In this configuration, north magnet poles A
and south magnet poles B are each built from 5 permanent magnet
sectors: [0098] 1 axially magnetized permanent magnet sector A21
(B21), [0099] 1 permanent magnet sector A22 (B22) magnetized
.about.60.degree. degrees clockwise to the axle direction, [0100] 1
permanent magnet sector A23 (B23) magnetized .about.60.degree.
counter-clockwise, and [0101] 2 permanent magnet sectors T1 and T2
magnetized tangentially.
[0102] Therefore in this construction there are four different
sorts of permanent magnet sector pieces used.
[0103] The Halbach-based constructions shown in FIGS. 3-5 may be
advantageous in that they may produce good magnetic flux levels.
However, they may be disadvantageous because each may require
assembling the rotors from numerous different types of magnets, a
requirement which may add to cost and complexity of the logistics
and assembly processes. Using multiple types of magnet pieces may
also lead to multiplication in the number of press-mould tooling
and magnetization fixtures required in the manufacturing process of
the magnet pieces themselves, since each type may need to be
pressed under differently directed domain-orienting magnetic
fields, and then may require to be magnetized by differently
directed magnetizing fields.
[0104] Attention is now drawn to FIG. 6, which may be thought of as
an attempt to provide a wholly active magnetic path (as does
Halbach) with a less complex design, according to methods of prior
art. FIG. 6 is adapted from U.S. Pat. No. 5,783,885 to Richard F.
Post, and shows a yokeless heteropolar magnet system in which
axially magnetized sectors (N and S, labeled A and B in the figure)
alternate with tangentially magnetized sectors T2. North sectors A,
generating essentially axial flux F and south sectors B generating
essentially axial flux G are interposed with interpole magnet
sectors T2 generating tangential fluxes K. This design is
relatively simple, but it does not provide a magnetic field which
is completely concentrated near the working face of the disk, as
the case with Halbach designs. Rather than distributing the
magnetic flux above the working face (in the figure, the side where
fluxes F and G are marked), as would typically be produced by a
Halbach design, the design shown in FIG. 6 may provide only about
80% of flux above the working face. Applicant estimates that
roughly 20% of the magnetic field will leak to the wrong side of
the disk. In other words, the design shown in FIG. 6 may be much
less efficient than Halbach designs.
[0105] Attention is now drawn to FIG. 7, which shows another
yokeless heteropolar magnet system, according to methods of prior
art. FIG. 7 is adapted from U.S. Patent Application 2011/024567A1
by Mark J. Blackwelder et al. FIG. 7 shows a yokeless system in
which soft magnetic sectors H are interposed between north sectors
A and south sectors B. Sectors A and B generate essentially axial
flux. Soft magnetic sectors II provide a path for closure of those
fluxes. This design may also fail to provide a magnetic field which
is completely concentrated near the working face of the disk.
Rather, Applicant estimates that the design of FIG. 7 may leave a
substantial part of the magnetic field (perhaps up to about 30%)
beyond the disk and near its external non-working face. So this
prior art design, while relatively simple because it may be
constructed using only one type of axially magnetized simple
prismatic magnet, may be relatively inefficient.
[0106] As discussed briefly above, prior art systems similar to
those shown in FIGS. 1 and 2 may suffer from low efficiency in the
use of the spatial volume available for the rotor, potentially
resulting in lowered electrical efficiency. Prior art systems
similar to those shown in FIGS. 3-5 may provide higher efficiency,
but may suffer from greater complexity, and concomitant resultant
disadvantages such as greater cost of construction as compared to
systems such as those of FIGS. 1 and 2. Systems such as those
presented in FIGS. 6 and 7 are less complex and may be easier to
construct, but may not be very efficient.
DESCRIPTIONS OF SOME EMBODIMENTS
[0107] Some embodiments described herein may provide greater
efficiency in the use of space available for a planar rotor of an
electric machine as compared to some electrical machine designs
known to prior art. Some embodiments described herein may be
simpler, easier, and/or less expensive to build as compared to
space-efficient designs known to prior art.
[0108] In some embodiments, an axial air-gap electric machine with
a rotational axis comprises at least one discoidal rotor having
alternating north and south magnetic poles. Optionally, each pole
consists of a pair of magnets whose magnetization orientation is
tilted by between 15.degree. and 75.degree. and/or by between
30.degree. and 60.degree. and/or optionally by about 45.degree.
degrees with respect to the orientation of the rotational axis.
[0109] For each pair, the axial components of the magnetization of
the component magnets are co-directional, while their tangential
components are counter-directional.
[0110] In a first set of pairs, the magnetizations of the two
magnets of the pair are oriented so that their axial components
(optionally of equal strength) are oriented towards the working
face of the rotor and their tangential components are oriented
towards each other. Pairs of this first set create the north poles
of the rotor.
[0111] In a second set of pairs, the magnetization of the two
magnets of the pair are oriented so that their axial components
(optionally of equal strength) are oriented away from the working
face of the rotor and their tangential components are oriented away
from each other. Pairs of this second set create the south poles of
the rotor.
[0112] In some embodiments, a pair from the first set alternates
with a pair from the second set around the rotor, creating
alternating north and south poles around the rotor.
[0113] In some embodiments the magnets are essentially identical in
physical form while differing in magnetic orientation. In some
embodiments, the magnets are butt-jointed as shown in FIG. 8A.
[0114] In some embodiments, some or all of the component magnets
are slightly spaced from each other, as discussed below. In some
embodiments magnets having a tangential magnetization component
directed in a clockwise direction alternate with magnets having a
tangential magnetization component directed in a counterclockwise
direction, and both are interposed between south and north poles
and alternated with each other.
[0115] In some embodiments a soft magnetic back yoke is provided.
In some embodiments the yoke is provided with ribs. In some
embodiments the yoke is provided without ribs. In some embodiments
the yoke is provided with openings, optionally radial slot-like
openings, which may be useful for cooling. In some embodiments, no
yoke openings are provided.
[0116] Embodiments of the present invention can be constructed
using various types of magnetic material and using magnetic
elements of varying dimensions. In general it is noted that in the
figures presented herein, embodiments are generally shown as having
configurations which are generally symmetrical formats, for example
having magnetic pieces of identical sizes and shapes positioned
radially and symmetrically, and with magnetic poles uniformly
spaced and of uniform size. However, it is noted that such identity
and symmetry of sizes and shapes and positions and spacings is not
to be considered limiting: the invention may be practiced and
embodiments may be constructed using magnetic and non-magnetic
components which may be of same and/or of varying sizes and shapes
and which may be positioned symmetrically and/or a-symmetrically,
radially and/or non-radially, with uniform and/or non-uniform pole
sizes and spacings and magnetic orientations, and all such
variations are contemplated as embodiments of the present
invention.
[0117] It is further noted that with reference to various
embodiments described herein, reference is made to magnetic
components and to magnetic flux having particular orientations and
directions. For example, various references are made to elements
whose magnetic orientation has an "axial" component and a
"tangential" component. It is noted that such components also have
an additional component neither axial nor tangential, and that
components so oriented are also included in the scope of the
described invention.
[0118] Some embodiments comprise only two types of permanent magnet
pieces, and in some embodiments which comprise only two types of
permanent magnet pieces those pieces optionally have a same
physical shape and a different magnetic orientation.
[0119] In general, the Applicant has found good efficiencies to be
achieved when thickness of the magnetic elements is approximately
half the length of the magnetic poles constructed by the magnetic
pieces as explained below, but this consideration also is not to be
considered as limiting, and constructions of various thickness
and/or of relative dimensions differing from those shown in
exemplary embodiments herein are also contemplated as embodiments
of the invention.
[0120] In some embodiments, an electric machine comprises rotors
according to embodiments of the invention described herein, and
further comprises one or more conventional axial flux permanent
magnet rotors.
[0121] In some embodiments of the invention, a planar object has at
least one and optionally two surfaces which are nearly
geometrically planar, over at least 80% or 90% or more of their
surface area. Optionally, the surface is nearly planar when it is
within 5% or 10% of a flat plane passing through the surface, the
percentage being the arithmetic average thickness of the object. In
an exemplary embodiment of the invention, the two surfaces are
substantially parallel (e.g., with an angle of between 175 and 195
degrees between two planes that each approximate a surface (e.g.,
using an RMS approximation of mass of parts of the surface)).
[0122] In an exemplary embodiment of the invention, the planar
object has a thickness with is less than 30%, 20%, 10% or
intermediate percentages of a maximal dimension of the object.
[0123] In some embodiments, a disk shape is used which approximates
(e.g., within 10%, 5% or better per dimension) a straight prism
with dimensions of its base surfaces which are less (e.g., 20%, 10%
or intermediate or smaller percentages) of its height.
[0124] In some embodiments, a disk-shaped object is a planar
object, for example, with a diameter which is less than 20%, 10% or
intermediate percentages of its maximal extent in other
dimensions.
[0125] Before explaining at least one embodiment of the invention
in detail, it is to be understood that the invention is not
necessarily limited in its application to the details of
construction and the arrangement of the components and/or methods
set forth in the following description and/or illustrated in the
drawings and/or the Examples. The invention is capable of other
embodiments or of being practiced or carried out in various
ways.
[0126] Attention is now drawn to FIG. 8A, which is an exploded
perspective view of a rotor for an electrical machine in which at
least some magnetic poles (each pole, in this exemplary figure)
comprises two side-facing magnets, according to some embodiments of
the present invention. As shown in the figure, in some embodiments
at least some poles (each pole in this exemplary figure) are made
from two butt-jointed magnets each magnetized by an angle of
between 30.degree. and 60.degree. to the axis, and optionally about
45.degree.. (In some embodiments, magnetization angles of between
15.degree. and 75.degree. are contemplated.) The tangential
magnetization components of these butt-jointed magnets are
oppositely directed, while their axial magnetization components are
co-directed. The result is alternating north and south poles. In
some embodiments the butt-jointed magnets are of identical shapes
and/or differing magnetic orientations.
[0127] In some embodiments, the magnets are radially oriented. In
some embodiments pairs of magnets forming poles are also
butt-jointed to each other.
[0128] FIG. 8A shows an exemplary rotor 1000 having a planar
frame-like yoke 2100 on which 20 south poles 1110 and 20 north
poles 1210 are positioned. Poles 1110 and 1210 are secured on yoke
2100 and retained thereon by a hub 2300 and optionally by a ring
2200.
[0129] At least some south poles 1110 (each south pole, in this
exemplary and non-limiting embodiment) consists of two essentially
identical butt-jointed magnetized pieces 1111A and 1111B. In some
embodiments the two pieces are magnetized by about 45.degree. (in
some embodiments by between 30.degree. and 60.degree., in some
embodiments by between 15.degree. and 75.degree.) relative to the
axis as shown by arrows 1112A and 1112B respectively. The
tangential components of these arrows 1112A and 1112B of these
radial butt-jointed magnet pieces are oppositely directed while
their axial magnetization components are co-directed toward the
yoke 2100.
[0130] Similarly, at least some north poles 1210 (each north pole
in this exemplary and non-limiting embodiment) consists of two
essentially identical butt-jointed pieces 1211A and 1211B
magnetized by about 45 degrees (in some embodiments by between
30.degree. and 60.degree., in some embodiments by between
15.degree. and 75.degree.) relative to the axis as shown by arrows
1212A and 1212B respectively. The tangential components of these
arrows 1212A and 1212B are also oppositely directed while their
axial magnetization components are co-directed outward from the
yoke 2100. The poles 1110 and 1210 themselves are also optionally
butt-jointed to each other.
[0131] In some embodiments, adjacent faces 1119 of south poles 1110
and adjacent faces 1219 of north poles 1210 are placed on radial
yoke sections 2120. Inter-pole border sides are optionally placed
on radial slots 2110. Twenty north and twenty south poles are shown
in the Figure, but it is to be understood that that number (in this
figure and in other figures herein) is exemplary and not limiting.
North and south poles as shown are oriented at 180.degree. from
each other, but this characteristic also is exemplary and not
limiting.
[0132] FIG. 8B shows a non-exploded view of the rotor of FIG. 8A
and an expanded detail of a portion of that rotor, according to
some embodiments of the present invention.
[0133] The rotor presented in FIGS. 8A and 8B, as well as other
designs described herein, may have a magnetic efficiency near that
of an ideal Halbach system. Some embodiments, for example, provide
more than 90.degree. of the amount of flux available from a Halbach
system of comparable size and weight; yet comprise only two types
of permanent magnet components. However, construction and
manufacture of an embodiment such as that presented in FIGS. 8A and
8B may be more simple and less costly than corresponding Halbach
systems, since (as shown above in examples from prior art) Halbach
systems (for example, that shown in FIG. 7) comprise multiple
different magnetic units and/or multiple orientations for similar
magnetic units, whereas only two orientations and/or two types
magnetic unit components suffice to construct an embodiment as
shown in FIGS. 8A and 8B.
[0134] Attention is now drawn to FIG. 9, which is a view of a rotor
according to an embodiment of the present invention. Rotor 3000
differs from rotor 1000 in that rotor 3000 comprises gaps 3101
between south poles 1110 and north poles 1210. In some embodiments
gaps 3101 are useful to provide improved ventilation through the
gaps. A plurality of identical gaps are shown in the figure, but it
is to be understood that this configuration is exemplary and not
limiting, gaps 3101 may be of non-identical sizes and may
optionally be present between some poles and not present between
other poles.
[0135] In some embodiments gaps 3101 may be used for construction
elements. For example, gaps 3101 may be filled by an epoxy
compound.
[0136] Attention is now drawn to FIG. 10A, which shows an exploded
view of a rotor 4000, and to FIG. 10B showing a perspective and a
detail view of that rotor, according to some embodiments of the
present invention. Rotor 4000 differs from rotor 3000 in that rotor
4000 comprises a ribbed yoke 4100, whereas rotor 3000 comprises a
planar yoke. Rotor 4000 comprises ribs 4115 placed on radial yoke
sections 4120 between radial slots 4110, and which are therefore
positioned between south poles 1110 and north poles 1210. Ribs 4115
are made from soft-magnetic material, so as to conduct magnetic
flux as shown by arrows 4310 of FIG. 10B. In some embodiments ribs
4115 are constructed as integral parts of yoke 4100. As may be seen
from the figure, two butt-jointed permanent magnets may be
positioned between each pair of ribs, or between some pairs of
ribs.
[0137] Ribs 4115 may be advantageous in that they may improve rotor
rigidity. To avoid a decrease in magnetic flux caused by the gaps
between successive permanent magnets thus created, in some
embodiments ribs 4115 may be constructed of magnetic
flux-conducting material.
[0138] Attention is now drawn to FIG. 11A showing an exploded view
of a rotor 5000, also having a ribbed yoke, and to FIG. 11B showing
a perspective view and a detail view of rotor 5000, according to
some embodiments of the present invention.
[0139] FIG. 11A shows rotor 5000 having a ribbed yoke 5100 on which
(in the exemplary embodiment pictured) 20 south poles 1110 and 20
north poles 1210 are allocated. Some or all of poles 1110 and 1210
may each comprise two butt-jointed magnets. In some embodiments
these south and north poles are secured on yoke 5100 and retained
thereon by a hub 2300, ribs 5111, 5112, and 5210, and/or optionally
by a ring 2200. Optionally each south pole 1110 consists of two
optionally identically shaped magnets 1111A-1111B magnetized by
about 45.degree. (in some embodiments between 30.degree. and
60.degree., in some embodiments between 15.degree. and 75.degree.)
relative to the axis in different tangential directions toward yoke
5100 as shown by the small arrows in the figure. Magnets 1111A and
1111B are separated by spaced gaps 5101. Similarly, optionally some
or each north pole 1210 consists of two essentially identical
magnets 1211A-1211B magnetized by about 45.degree. (in some
embodiments between 30.degree. and 60.degree., in some embodiments
between 15.degree. and 75.degree.) relative to the axis in
different tangential directions toward yoke 5100 as shown by the
small arrows in the figure. Magnets 1211A and 1211B are also
optionally separated by gaps 5101.
[0140] Yoke ribs 5111, which may optionally be made of non-magnetic
material, are interposed between magnet pieces 1111A-1111B of south
poles 1110. Similarly, yoke ribs 5121, which may optionally be made
from non-magnetic material, are optionally interposed between
magnet pieces 1211A-1211B of north poles 1210.
[0141] Yoke ribs 5210, which separate north poles 1110 from south
poles 1120, are optionally made of soft magnetic material. Ribs
5210 conduct magnetic flux as shown by arrows 5310 and may
optionally be made as part of yoke 5100. The ribbed structure of
rotor 5000 significantly improves rotor rigidity, yet the
inter-magnet gaps may not decrease the flux since they may be
filled by magnetic flux-conducting material.
[0142] Attention is now drawn to FIGS. 12A and 12B. FIG. 12A
presents an exploded view of a yokeless rotor 6000, and FIG. 12B
presents a perspective view and a detailed view of rotor 6000,
according to some embodiments of the present invention.
[0143] Exemplary rotor 6000 comprises 20 south poles 1110, 20 north
poles 1210, interpole magnet pieces 6110 magnetized tangentially in
a counter-clockwise direction and interpole magnet pieces 6120
magnetized tangentially in clockwise direction. Pieces 6110 are
positioned counter-clockwise of south poles 1110 and oriented in a
counter-clockwise direction, while pieces 6120 are allocated
clockwise of north poles 1210 and oriented in a clockwise
direction. Optionally, all magnet pieces 1111A, 1111B, 1211A,
1211B, 6110, 6120 are retained by a hub 2300 and ring 2200. Each
south pole 1110 consists of two (optionally having a same shape
and/or optionally butt-jointed) magnet pieces 1111A and 1111B
magnetized by about 45.degree. degrees (in some embodiments,
between 30.degree. and 60.degree., in some embodiments between
15.degree. and 75.degree.) relative to the rotational axis, so that
axial components of their magnetization are directed outward from
the working face, and the two magnets of the pair have tangential
magnetization components oriented in different tangential
directions, as shown by arrows. Similarly each north pole 1210
consists of two (optionally having a same shape and/or optionally
butt-jointed) magnetic pieces 1211A and 1211B magnetized by about
45.degree. degrees (in some embodiments, between 30.degree. and
60.degree., in some embodiments between 15.degree. and 75.degree.)
relative to the axis, their magnetization being oriented toward the
working face of the rotor and having tangential directions
different one from the other, as shown by arrows. Yokeless rotor
6000 may be useful in contexts where totally steel-less
construction is required.
[0144] Attention is now drawn to FIGS. 13A and 13B, which present a
two-magnet layer rotor 7000 optionally comprising a planar
frame-like yoke 2100 on which (in this non-limiting exemplary
embodiment) 20 south poles 7110 and 20 north poles 7210 are
provided and are optionally secured on yoke 2100 and retained
thereon by a hub 2300 and optionally by a ring 2200. Each south
pole 7110 consists of 2 magnet layers as shown in the figure:
[0145] a first layer like that disclosed in FIG. 8, consists of two
(optionally same-shaped, optionally butt-jointed) magnetic pieces
7111A and 7111B magnetized by about 45.degree. (or optionally
30.degree.-60.degree., or optionally 15.degree.-75.degree.) to the
axis and away from each other and away from the working face and
toward yoke 2100 (if present); and [0146] a second layer which
comprises a magnet piece 7111 axially magnetized away from the
working face and toward yoke 2100 if present.
[0147] In similar manner, each north pole 7210 comprises two magnet
layers, a first layer like that disclosed in FIG. 8 and consisting
of two optionally identically shaped optionally butt-jointed pieces
7211A and 7211B each magnetized by about 45.degree. (or optionally
30.degree.-60.degree., or optionally 15.degree.-75.degree.) to the
axis outward from yoke 2100, and a second layer which is a single
magnet piece 7211 axially magnetized toward the working face and
away from yoke 2100 if present.
[0148] Attention is now drawn to FIGS. 14 and 15, which shows an
exemplary rotor assembly 8000 comprising two identical rotors 1000A
and 1000B as disclosed in FIG. 8 and useable in an axial field
electric machine. As shown by the arrows in the insert, a magnetic
flux is generated in a gap 9300 between the rotors. The flux
comprises adjacent pole sections of counter-directed axial magnetic
flux 8100 and 8200. Rotors 1000A and 1000B are attracted to each
other by the magnetic forces and are held in a fixed physical
relationship to each other through hubs 2300A and 2300B providing a
desirable value of magnetic flux 8100, 8200. FIG. 15 shows how an
axial field electric machine 9000 may be constructed using a rotor
assembly 8000 as disclosed in FIG. 14 and comprising 2 identical
rotors 1000A and 1000B, and having a flat disk-type stator 9100
introduced into the gap 8200 between rotors 1000A and 1000B.
Distances between rotors and stator are exaggerated for clarity of
the figure.
[0149] Attention is now drawn to FIGS. 16 and 17. FIG. 17 provides
an approximate and non-limiting table of calculation results
providing an approximate comparison between the magnetic flux
estimated as being generated by some embodiments of the present
invention as compared to magnetic flux estimated as being generated
by some prior art configurations. The table of FIG. 17 compares
estimated fluxes generated according to various magnetic designs
assuming similar overall dimensions and weight of the components.
FIGS. 16A and 16B are provided to facilitate understanding of the
table of FIG. 17 by showing in summary fashion various designs for
which estimated flux has been calculated.
[0150] Attention is now drawn to FIG. 18 which shows a multi-stage
modular axial flux machine 9500 according to some embodiments of
the present invention. In an exemplary embodiment shown in FIG. 18,
machine 9500 comprises two end rotors 1000A and 1000B according to
embodiments of the present invention and two conventional axial
flux permanent magnet rotors 1900-1, 1900-2, all rotors optionally
having same numbers of axially magnetized poles. Machine 9500
further comprises three coreless stators 9100-1, 9100-2, 9100-3
interposed between rotors 1000A, 1000B, 1900-1, 1900-2. Internal
rotors 1900-1 and 1900-2 in common with end rotors 1000A and 1000B
generate axial magnetic flux 8500 which makes closure in end rotors
1000A and 1000B and crosses stators 9100-1, 9100-2, and 9100-3.
[0151] Attention is now drawn to FIG. 19 which shows a conventional
axial flux permanent magnet rotor 1900 referred in FIG. 18. Rotor
1900 carries alternating north and south magnetic poles magnetized
essentially in an axial direction, and optionally comprises a
constructive element, e.g. hub 1920 on which said magnet poles are
secured.
[0152] It is expected that during the life of a patent maturing
from this application many relevant electrical machines will be
developed, and the scope of the term "electrical machine" is
intended to include all such new technologies a priori.
[0153] As used herein the term "about" refers to .+-.15%.
[0154] The terms "comprises", "comprising", "includes",
"including", "having" and their conjugates mean "including but not
limited to".
[0155] The term "consisting of" means "including and limited
to".
[0156] Throughout this application, various embodiments of this
invention may be presented in a range format. It should be
understood that the description in range format is merely for
convenience and brevity and should not be construed as an
inflexible limitation on the scope of the invention. Accordingly,
the description of a range should be considered to have
specifically disclosed all the possible subranges as well as
individual numerical values within that range. For example,
description of a range such as from 1 to 6 should be considered to
have specifically disclosed subranges such as from 1 to 3, from 1
to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6 etc., as
well as individual numbers within that range, for example, 1, 2, 3,
4, 5, and 6. This applies regardless of the breadth of the
range.
[0157] Whenever a numerical range is indicated herein, it is meant
to include any cited numeral (fractional or integral) within the
indicated range. The phrases "ranging/ranges between" a first
indicate number and a second indicate number and "ranging/ranges
from" a first indicate number "to" a second indicate number are
used herein interchangeably and are meant to include the first and
second indicated numbers and all the fractional and integral
numerals therebetween.
[0158] It is appreciated that certain features of the invention,
which are, for clarity, described in the context of separate
embodiments, may also be provided in combination in a single
embodiment. Conversely, various features of the invention, which
are, for brevity, described in the context of a single embodiment,
may also be provided separately or in any suitable subcombination
or as suitable in any other described embodiment of the invention.
Certain features described in the context of various embodiments
are not to be considered essential features of those embodiments,
unless the embodiment is inoperative without those elements.
[0159] Although the invention has been described in conjunction
with specific embodiments thereof, it is evident that many
alternatives, modifications and variations will be apparent to
those skilled in the art. Accordingly, it is intended to embrace
all such alternatives, modifications and variations that fall
within the spirit and broad scope of the appended claims.
[0160] All publications, patents and patent applications mentioned
in this specification are herein incorporated in their entirety by
reference into the specification, to the same extent as if each
individual publication, patent or patent application was
specifically and individually indicated to be incorporated herein
by reference. In addition, citation or identification of any
reference in this application shall not be construed as an
admission that such reference is available as prior art to the
present invention. To the extent that section headings are used,
they should not be construed as necessarily limiting.
* * * * *