NZ753663B2 - Array of three pole magnets - Google Patents
Array of three pole magnets Download PDFInfo
- Publication number
- NZ753663B2 NZ753663B2 NZ753663A NZ75366317A NZ753663B2 NZ 753663 B2 NZ753663 B2 NZ 753663B2 NZ 753663 A NZ753663 A NZ 753663A NZ 75366317 A NZ75366317 A NZ 75366317A NZ 753663 B2 NZ753663 B2 NZ 753663B2
- Authority
- NZ
- New Zealand
- Prior art keywords
- magnet
- pole
- magnets
- magnetic
- array
- Prior art date
Links
- 230000005291 magnetic Effects 0.000 claims abstract description 163
- 230000004907 flux Effects 0.000 claims description 24
- 239000000843 powder Substances 0.000 description 75
- 238000000034 method Methods 0.000 description 69
- 238000010586 diagram Methods 0.000 description 40
- 238000004519 manufacturing process Methods 0.000 description 36
- 239000000463 material Substances 0.000 description 36
- 238000003825 pressing Methods 0.000 description 21
- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 14
- 230000035699 permeability Effects 0.000 description 12
- 238000007373 indentation Methods 0.000 description 11
- 230000005415 magnetization Effects 0.000 description 10
- 229910052742 iron Inorganic materials 0.000 description 7
- 230000015572 biosynthetic process Effects 0.000 description 6
- 238000005755 formation reaction Methods 0.000 description 6
- 239000002245 particle Substances 0.000 description 6
- 238000005245 sintering Methods 0.000 description 5
- 229910000831 Steel Inorganic materials 0.000 description 4
- UONOETXJSWQNOL-UHFFFAOYSA-N Tungsten carbide Chemical compound [W+]#[C-] UONOETXJSWQNOL-UHFFFAOYSA-N 0.000 description 4
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 description 4
- 239000010941 cobalt Substances 0.000 description 4
- 229910052803 cobalt Inorganic materials 0.000 description 4
- 239000003302 ferromagnetic material Substances 0.000 description 4
- 239000010959 steel Substances 0.000 description 4
- 238000009826 distribution Methods 0.000 description 3
- 241001272720 Medialuna californiensis Species 0.000 description 2
- 238000004590 computer program Methods 0.000 description 2
- 230000002349 favourable Effects 0.000 description 2
- 230000001976 improved Effects 0.000 description 2
- 230000001939 inductive effect Effects 0.000 description 2
- 238000005304 joining Methods 0.000 description 2
- 239000000696 magnetic material Substances 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 229910001172 neodymium magnet Inorganic materials 0.000 description 2
- 238000004804 winding Methods 0.000 description 2
- 229910001369 Brass Inorganic materials 0.000 description 1
- 238000005299 abrasion Methods 0.000 description 1
- 238000005296 abrasive Methods 0.000 description 1
- 229910045601 alloy Inorganic materials 0.000 description 1
- 239000000956 alloy Substances 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- REDXJYDRNCIFBQ-UHFFFAOYSA-N aluminium(3+) Chemical class [Al+3] REDXJYDRNCIFBQ-UHFFFAOYSA-N 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminum Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 230000000712 assembly Effects 0.000 description 1
- 239000010951 brass Substances 0.000 description 1
- 238000005219 brazing Methods 0.000 description 1
- 239000000969 carrier Substances 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 230000000875 corresponding Effects 0.000 description 1
- 238000007723 die pressing method Methods 0.000 description 1
- 239000003292 glue Substances 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 239000012212 insulator Substances 0.000 description 1
- 238000003754 machining Methods 0.000 description 1
- 230000005381 magnetic domain Effects 0.000 description 1
- 229910000734 martensite Inorganic materials 0.000 description 1
- 239000007769 metal material Substances 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000006011 modification reaction Methods 0.000 description 1
- -1 neodymium iron boron Chemical compound 0.000 description 1
- 230000001902 propagating Effects 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 239000011343 solid material Substances 0.000 description 1
- 238000003860 storage Methods 0.000 description 1
- 239000004557 technical material Substances 0.000 description 1
- 239000010936 titanium Substances 0.000 description 1
- RTAQQCXQSZGOHL-UHFFFAOYSA-N titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 1
- 229910052719 titanium Inorganic materials 0.000 description 1
Abstract
array of magnets, comprising: first three-pole magnets and second three-pole magnets arranged in an array in which each of the first three-pole magnets is interfaced with an adjacent one or more of the second three-pole magnets; wherein each of the first three-pole magnets comprises: a first magnet first magnetic pole having a first magnetic polarity at a first magnet first surface of the first three-pole magnet; a first magnet second magnetic pole having a second magnetic polarity at a first magnet second surface of the first three-pole magnet, wherein the second magnetic polarity is opposite the first magnetic polarity, and wherein the first magnet second surface is adjacent to and at least partly orthogonal to the first magnet first surface; and a first magnet third magnetic pole having the second magnetic polarity at a first magnet third surface of the first three-pole magnet, wherein the first magnet third surface is adjacent to the first magnet first surface and disposed on a substantially opposite side of the first three-pole magnet relative to the first magnet second surface; and wherein each of the second three-pole magnets comprises: a second magnet first magnetic pole having the second magnetic polarity at a second magnet first surface of the second three-pole magnet; a second magnet second magnetic pole having the first magnetic polarity at a second magnet second surface of the second three-pole magnet, wherein the second magnet second surface is adjacent to and at least partly orthogonal to the second magnet first surface; and a second magnet third magnetic pole having the first magnetic polarity at a second magnet third surface of the second three-pole magnet, wherein the second magnet third surface is adjacent to the second magnet first surface and disposed on a substantially opposite side of the second three-pole magnet relative to the second magnet second surface. et first magnetic pole having a first magnetic polarity at a first magnet first surface of the first three-pole magnet; a first magnet second magnetic pole having a second magnetic polarity at a first magnet second surface of the first three-pole magnet, wherein the second magnetic polarity is opposite the first magnetic polarity, and wherein the first magnet second surface is adjacent to and at least partly orthogonal to the first magnet first surface; and a first magnet third magnetic pole having the second magnetic polarity at a first magnet third surface of the first three-pole magnet, wherein the first magnet third surface is adjacent to the first magnet first surface and disposed on a substantially opposite side of the first three-pole magnet relative to the first magnet second surface; and wherein each of the second three-pole magnets comprises: a second magnet first magnetic pole having the second magnetic polarity at a second magnet first surface of the second three-pole magnet; a second magnet second magnetic pole having the first magnetic polarity at a second magnet second surface of the second three-pole magnet, wherein the second magnet second surface is adjacent to and at least partly orthogonal to the second magnet first surface; and a second magnet third magnetic pole having the first magnetic polarity at a second magnet third surface of the second three-pole magnet, wherein the second magnet third surface is adjacent to the second magnet first surface and disposed on a substantially opposite side of the second three-pole magnet relative to the second magnet second surface.
Description
ARRAY OF THREE POLE MAGNETS
BACKGROUND OF THE INVENTION
Magnets are useful for a variety of applications such as magnet arrays for
electric motors. For example, one type of electric motor is a surface permanent magnet motor
in which a rotor is implemented by an array of alternating pole magnets or a Halbach array.
Ideally, the magnet array has a concentrated magnetic field on one side of the magnet array
and substantially no magnetic field on the other side of the array. However, current magnet
arrays are unable to shape magnetic fields in this manner. Currently, the manufacture of
magnets and magnet arrays is complex and costly, and the magnets may be inefficient and do
not always perform as desired.
BRIEF DESCRIPTION OF THE DRAWINGS
Various embodiments of the invention are disclosed in the following detailed
description and the accompanying drawings.
is a diagram of an embodiment of a three pole magnet.
is a diagram of an embodiment of a three pole magnet.
is a diagram of an embodiment of a three pole magnet having an
indentation.
is a diagram of an embodiment of an array of three pole magnets.
is a diagram of a magnetic field in a magnet array according to an
embodiment.
is a flow chart illustrating an embodiment of a process to manufacture a
three-pole magnet.
is a diagram of a magnetic field of an assembly to produce a three pole
magnet blank at a beginning of a production process according to an embodiment.
is a diagram of a magnetic field of a three pole magnet at a completion
of a pressing process according to an embodiment.
is a diagram of a magnetic field of a three pole magnet at a beginning
of a pressing process according to an embodiment.
is a diagram of a magnetic field of a three pole magnet at a completion
of a pressing process according to an embodiment.
is a diagram of an embodiment of a die for producing a three pole
magnet.
is a diagram of an embodiment of a die for producing a three pole
magnet.
is a diagram of an embodiment of a punch for producing a three pole
magnet.
is a diagram of an embodiment of an assembly for producing a three
pole magnet.
A is a diagram of an embodiment of a process to manufacture a three-
pole magnet.
B is a diagram of an embodiment of a process to manufacture a three-
pole magnet.
C is a diagram of an embodiment of a process to manufacture a three-
pole magnet.
A is a diagram of an embodiment of a motor including an array of
magnets according to an embodiment.
B is a cross-sectional exploded view of the motor. is a
diagram of an embodiment of a magnet array.
is a diagram of an embodiment of a magnet array.
DETAILED DESCRIPTION
The invention can be implemented in numerous ways, including as a process;
an apparatus; a system; a composition of matter; a computer program product embodied on a
computer readable storage medium; and/or a processor, such as a processor configured to
execute instructions stored on and/or provided by a memory coupled to the processor. In this
specification, these implementations, or any other form that the invention may take, may be
referred to as techniques. In general, the order of the steps of disclosed processes may be
altered within the scope of the invention. Unless stated otherwise, a component such as a
processor or a memory described as being configured to perform a task may be implemented
as a general component that is temporarily configured to perform the task at a given time or a
specific component that is manufactured to perform the task. As used herein, the term
‘processor’ refers to one or more devices, circuits, and/or processing cores configured to
process data, such as computer program instructions.
A detailed description of one or more embodiments of the invention is
provided below along with accompanying figures that illustrate the principles of the
invention. The invention is described in connection with such embodiments, but the
invention is not limited to any embodiment. The scope of the invention is limited only by the
claims and the invention encompasses numerous alternatives, modifications and equivalents.
Numerous specific details are set forth in the following description in order to provide a
thorough understanding of the invention. These details are provided for the purpose of
example and the invention may be practiced according to the claims without some or all of
these specific details. For the purpose of clarity, technical material that is known in the
technical fields related to the invention has not been described in detail so that the invention
is not unnecessarily obscured.
Techniques to provide a three-pole magnet, an array of three pole magnets, a
method of making a three pole magnet, and a method of making an array of magnets are
disclosed. For example, an array of magnets includes a plurality of three-pole magnets
arranged in an array in which each three-pole magnet comprising the array is adjacent to one
or more other three-pole magnets comprising the array. At least one of the three-pole magnets
comprises: a first surface comprising a first magnetic pole having a first magnetic polarity, a
second surface that is adjacent to and at least partly orthogonal to the first surface and which
comprises a second magnetic pole having a second magnetic polarity that is opposite the first
magnetic polarity, and a third surface that is adjacent to the first surface at an end
substantially opposite the second surface and which comprises a third magnetic pole having
the second magnetic polarity.
In magnet manufacture, there is frequently a tradeoff between manufacturing
complexity (e.g., cost) and performance. Techniques disclosed herein address this tradeoff by
achieving high performance with lower cost and complexity compared with typical magnet
and magnet array manufacture processes. Also disclosed herein are magnets and magnet
arrays with improved performance compared with typical magnets and magnet arrays.
Consequently, electric motors and machines using the magnets and magnet arrays disclosed
herein are improved.
Conventional manufacture of magnets involves starting with a large block of
isostatically pressed powder, sintering to solidify the block and to lock in a uniform
magnetization direction, dicing up the large block, machining or grounding the magnet to the
finished size, finishing the surface, and magnetizing the magnet. The resulting magnet has a
magnetization direction that is substantially uniform in orientation throughout the interior of
the magnet. When such a magnet is used in a Halbach array to provide a brushless motor, the
uniform orientation of the magnetic field results in wasted energy because there is still some
field on both sides of the array. It is the magnetic field that is located on the side of the
magnet array near a stator that interacts with the field generated by the stator to produce the
force that causes the rotor to rotate. The magnetic field on the side of the magnet array
opposite the stator is wasted.
In a typical magnetizing process, a magnetic field develops around solenoid
windings (coils), then expands and decays with time. For each point in the magnet, a
magnetic field of a certain strength is needed to force the magnetic domains to align. In
particular, the pulse reaching a central region of a magnet should have sufficient amplitude to
align the domains there. Typical materials used to create magnets have a single easy axis in
which the grains are aligned. The easy axis is an energetically favorable direction of
magnetization such that the material can be magnetized in one direction or the other along the
easy axis but generally not along any other axis.
The type and size of the material can pose challenges for magnetization. For
example, when there is a large area to be magnetized, eddy currents slow propagation of the
magnetizing field into that area. Effectively, this means that a relatively large piece of
material needs a relatively strong magnetic field to be magnetized. For many applications,
there are physical limitations to the strength of magnetic field that is capable of being
produced.
In contrast to typical magnets, which have a uniform magnetization direction
throughout the magnet, in various embodiments magnets disclosed here have optimally
oriented magnetization directions throughout the magnet. For example, the sintered grains of
the magnet cause the magnet to have a magnetic field like that of a Halbach array. For
example, at least a majority of the magnetic field enters through the top side of the array and
leaves through the adjacent sides, or vice versa, and less than a majority of the magnetic field
is on the bottom side of the array. The development of the magnetic field in various
embodiments is described here with respect to In some embodiments, an array made
of magnets described here may have better performance than a Halbach array because there
are fewer harmonics relative to a Halbach array. That is, a magnetic field of a magnet array
fabricated in accordance with techniques described herein may have a more ideal sinusoidal
shape than that of a traditional Halbach array or alternating pole magnet array. For example,
the field that would be in those wasted higher spacial harmonics in a Halbach array is moved
into a larger fundamental spacial harmonic due to the more ideal magnetization direction
distribution within the magnets.
is a diagram of an embodiment of a three pole magnet. The magnet
shown in has three poles, labelled 1, 2, and 3. The lines shown in the magnet are
example easy axis lines along which grains are aligned. An easy axis is an energetically
favorable direction of magnetization such that the material can be magnetized in one
direction or the other along the easy axis. In the example shown in , the three pole
magnet is capable of becoming magnetized along axis line 1 to 2 and along axis line 1 to 3.
The magnet shown in has substantially all of the field coming into (or
out of) the top surface (pole 1). The field splits substantially evenly and goes out of (or into)
two other surfaces (poles 2 and 3). In some embodiments, there is a fourth surface that has a
negligible amount of field coming in or going out. In , the fourth surface is the
bottom surface of the magnet.
is a diagram of an embodiment of a three pole magnet. The magnet
shown in includes three poles, labelled N (north), S (south), and S (south). The
magnet shown in behaves like the magnet shown in . As shown, there is one
north pole surface and two south pole surfaces. Alternatively, the magnet may have two north
pole surfaces and one south pole surface (not shown). In this example, substantially all of the
field coming into (or out of) the north pole, splits about evenly and goes out of the south
poles. The bottom surface has a negligible amount of field going out (or coming in). This
magnetic field may be generated according to the technique of In contrast to current
typical magnets, this magnet allow for better control of the magnetic field because, in
accordance with the techniques described herein, more of the magnetic field can be directed
to enter (or exit) one surface of the magnet than the opposite surface of the magnet compared
with conventional techniques.
is a diagram of an embodiment of a three pole magnet having an
indentation. The magnet of has the same grain lines as the magnet of and
consequently behaves like the magnet of . The difference between the magnet of
and the magnet shown here is an indentation 102 in which there is no magnet
material (e.g., a divot, notch, depression, etc.). In some embodiments, it may more difficult to
optimally align the grains of the magnet material on one of the surfaces of the magnet (e.g.,
the bottom surface in the example shown in ). Some magnet material may be
removed from the surface through which it is more difficult to align the grains of the magnet
material (e.g., the bottom surface in ) without affecting the performance of the
magnet while saving on the cost of production because less material is used. In the example
shown in , magnet material is not present in the indentation 102. In addition, the
indentation provides a location where the magnet may be labelled or identified. A magnetic
field for a magnet having an indentation is shown in
is a diagram of an embodiment of an array of three pole magnets. In
this example, the array includes three magnets. An example of a magnet provided in this
array of magnets is shown in FIGS. 1A-1C. In this example, the magnet array is made up of
two types of magnets: a first type that has a single north pole at top and a south pole on each
side adjacent to the top and a second type that has a single south pole at top and a north pole
on each side adjacent to the top. The magnets are oriented as shown such that opposite poles
would face at a magnet-to-magnet interface on the sides and the poles at the top surfaces
alternate between north and south.
is a diagram of a magnetic field in a magnet array according to an
embodiment. The magnetic field of the array shown in corresponds to the magnet
array shown in . Each magnet in the magnet array 226 is represented by a dashed
box. In the example shown, substantially all of the magnetic field is on the top side of the
array and substantially none (e.g., a negligible amount) of the magnetic field is on the bottom
side of the array. A magnetic field of this type may be desirable in application in which a
direction magnetic field is preferable. For example, a magnet array with this pattern of
magnetic field may replace Halbach arrays. The magnetic field in the magnet array 226 may
be produced by joining a plurality of magnets such as the magnet of FIGS. 1A-1C. The
magnets in the magnet array may be magnetized after they are placed in this formation or
they may be magnetized prior to being placed in this formation.
is a flow chart illustrating an embodiment of a process to manufacture a
three-pole magnet. In various embodiments, the process produces non-magnetized material
having a desired grain orientation (also called a “blank”). For example, the process produces
a block of material having the grain orientation shown in FIGS. 1A-1C such that the block of
material is capable of being magnetized to have three poles.
At 302, a die cavity is filled with magnet powder. In various embodiments, the
magnet powder includes any material with orientable grains such as neodymium iron boron
alloy (NdFeB). An example of a die that can be used to produce a three-pole magnet is shown
in FIGS. 8A and 8B. An example of an assembly that can be used for 302 is shown in 1120.1,
1120.2, and 1120.3 of A.
At 304, a magnetic field is induced through the magnet powder. The generated
magnetic field causes particles in the magnet powder to align along desired easy axis lines.
For example, the grains in the magnet powder are subjected to a field having flux lines to
which the grains align into the pattern shown in FIGS. 1A-1C. In various embodiments, the
magnetic field is induced when a magnetic circuit is closed. An example of an assembly
capable of generating a magnetic field is shown in . Example magnetic fields induced
through the magnet powder are shown in FIGS. 4-7. In one aspect, it can be easier to
magnetize a permanent magnet produced according to the techniques described here because
the grain easy axis lines guide the magnetization of the material to produce a permanent
magnet. In various embodiments, the magnetic field is pulsed through the magnet powder.
At 306, pressure is applied to the magnet powder to form a green form. In
various embodiments, the amount of pressure applied is pre-defined and adjustable. Green
form refers to a state of magnet powder after applied pressure causes the powder particles of
the magnet powder to fuse together such that when the pressure is released, the magnet
powder maintains its form. In various embodiments, a magnetic field is generated (304) and
pressure can be applied (306) substantially simultaneously. That is, the magnetic field is
pulsed to orient the grain lines along desires easy axes in the magnet powder while pressing
the powder. An example of an assembly that can be used for 306 is shown in 1150.1, 1150.2,
and 1150.3 of B.
At 308, pressure on the green form is released. In various embodiments, the
green form maintains its form upon release of pressure in 306. In some embodiments, the
green form is ejected from a die cavity. An example of an assembly that can be used for 308
is shown in 1170.1, 1170.2, and 1170.3 of C.
At 310, the green form is sintered to solidify the block. For example, sintering
the green form causes the material to solidify and lock in the easy axis directions. In one
aspect, the sintering creates a solid material by joining together the particles of the magnet
powder in the green form.
is a diagram of a magnetic field of an assembly to produce a three pole
magnet blank at a beginning of a production process according to an embodiment. The
production process is a pre-magnet production process transforms magnet powder into a
blank (also referred to as a pre-magnet). The magnet powder is pressed while being subjected
to a magnetic field to form a blank with one or more easy axes oriented as desired. Here, the
example state shows how flux flows through a magnetic circuit and magnet powder when a
magnetic field is initially induced through the magnet powder (304) in accordance with FIG.
The magnet producing assembly includes, among other parts, an armature 410,
at least one coil 412, a punch tip 414, and a die 404. The die 404 is adapted to receive magnet
powder 406. In various embodiments, the magnet powder is transformed into a permanent
magnet according to the techniques described here. The punch tip 414 is adapted to contact
the magnet powder 406 to shape the magnet powder and/or to apply pressure to the magnet
powder. The armature 410 is adapted to come into contact with the die 404 to form a
magnetic circuit. At least one coil is controlled to become energized after the formation of the
magnetic circuit. The energized coil(s) induces a magnetic field through the magnet powder
such that the powder grains are optimally aligned and remain optimally aligned following
completion of pressing process. An example of the magnet producing assembly is shown in
.
The example shown in corresponds to 304 of Here, a magnetic
field is induced but the punch tip 414 is not yet applying pressure on the magnet powder 406.
In some embodiments, the magnetic field is induced and the punch tip 414 contact the magnet
powder substantially simultaneously such that the magnetic field is induced and pressure is
applied to the magnet powder substantially simultaneously. In the example shown, magnetic
flux lines within the magnet 406 are orthogonal to the top and side surfaces of the magnet. In
some embodiments, in this state, the grain lines are aligned as shown, but might not remain
aligned until the pressing process is fully complete. In some embodiments, the amount of flux
entering or leaving the bottom surface is negligible.
is a diagram of a magnetic field of a three pole magnet at a completion
of a pressing process according to an embodiment. shows an example state of a
pressing assembly and magnet powder when pressing is completed. Here, the example state
shows how flux flows through a magnetic circuit and magnet powder at the completion of the
induction of a magnetic field through the magnet powder (304) in accordance with
For example, is the result of the end of a single pulse or the end of a series of pulsing.
The pressing assembly includes, among other parts, an armature 510, at least
one coil 512, at least one punch tip 514, and a die 504. The die 504 is adapted to receive
magnet powder 506. Each of these components may function like the corresponding
components described in unless otherwise described. An example of the magnet
producing assembly is shown in .
Unlike the assembly shown in the punch tip 514 is in contact with the
magnet powder 506. For example, the punch is applying pressure to the magnet powder while
the magnetic field is induced through the magnet powder. The example shown in
corresponds to 304 and 306 of In the example shown, magnetic flux lines within the
magnet 506 are orthogonal to the top and side surfaces of the magnet. In some embodiments,
the powder gains in the magnet 506 are optimally aligned will remain optimally aligned even
when pressing terminates. In some embodiments, the amount of flux entering or leaving the
bottom surface is negligible.
is a diagram of a magnetic field of a three pole magnet at a beginning
of a pressing process according to an embodiment. is a close up view of to
illustrate the block of material being pressed and surrounding areas. In this example, a punch
tip 614 does not fully contact the magnet 610. That is, the magnetic field is generated, but
pressure is not applied to the magnet. In the example shown, magnetic flux lines within the
magnet 610 are orthogonal to the top and side surfaces of the magnet.
In the example shown in the magnet 610 includes an indentation 612.
For example, the bottom punch in this area creates an indentation such that there is no magnet
material in the indentation. Some magnet material may be removed from the surface through
which it is more difficult to align the grains of the magnet material (e.g., the bottom surface
of magnet 610) without affecting the performance of the magnet while saving on the cost of
production because less material is used. In addition, the indentation provides a location
where the magnet may be labelled or identified. For example, the identification may register
the magnet block when it is becomes part of a magnet array.
is a diagram of a magnetic field of a three pole magnet at a completion
of a pressing process according to an embodiment. is a close up view of to
illustrate the block of material being pressed and surrounding areas. In this example, a punch
tip 714 is contacting the magnet 610. That is, the magnetic field is generated and pressure is
applied to the magnet substantially simultaneously. In the example shown, magnetic flux
lines within the magnet 710 are orthogonal to the top and side surfaces of the magnet. An
indentation 712 in magnet 710 may function like the one described for the magnet 610 of
is a diagram of an embodiment of a die for producing a three pole
magnet. is an exploded view of an example die that includes a first disk 820, a
second disk 840, a third disk 860, and a ring 880.
In this example, each of the first, second, and third disks includes a cavity 822.
When assembled as shown in , the cavities in each of the disks may be aligned. The
cavity can be adapted to receive magnet powder. In some embodiments, the lightly shaded
half-moon portions (822) of disk 820 are made of ferromagnetic material such as iron, steel,
high cobalt carbide, etc. In some embodiments, the half-moon portions (842) of disk 840 are
made of material with low magnetic permeability such as cemented tungsten carbide. That is,
the material does not easily support formation of a magnetic field and may function as an
insulator during a magnet production process such as the process shown in The
darkly-shaded area (844) surrounding the cavity may be made of material with high magnetic
permeability. That is, the material may easily support formation of a magnetic field and
facilitate production of a magnet from magnet powder in the cavity during a magnet
production process such as the process shown in The lightly-shaded middle section
(846) of disk 840 may be made of ferromagnetic material. In some embodiments, disk 860 is
made of material with low magnetic permeability such as cemented tungsten carbide. In
various embodiments, the ring 880 holds the disks 820-860 in place by exerting hoop stress
due to an interference fit. The ring may be made of a metallic material.
In various embodiments, the die cooperates with a punch to carry out the
process of For example, the die holds magnet powder while a magnetic field is
induced through the magnet powder and/or the punch exerts pressure on the magnet powder.
is a diagram of an embodiment of a die for producing a three pole
magnet. is a cross-sectional view of the example die described in . The ring
880 may compress the parts together with hoop stress. In some embodiments, the parts inside
ring 880 are joined by brazing or glue. In some embodiments, surfaces of cavity 822 are
made from abrasion resistant material such as tungsten carbide and the like. This may
facilitate production of the magnet and allow green form to be easily removed (e.g., ejected)
from the cavity.
is a diagram of an embodiment of a punch for producing a three pole
magnet. For example, the punch shown here is an upper punch that is adapted to provide
pressure on a top surface of a block of magnet powder during a magnet production process
such as the process of In the example shown, the punch includes a top portion 902, a
middle portion 904, at least one travel stop 906, at least one spring 908, armature 910, at least
one coil 912, and tip 914.
The top portion 902 may prevent stray magnetic fields generated by coil 912
from propagating elsewhere. For example, the top portion 902 may insulate the rest of a
machine in which the punch is provided. In various embodiments, the top portion is made of
non-magnetic material such as titanium, austenitic steel, aluminum, brass, etc. The non-
magnetic material may prevent stray magnetic fields from leaving a die and/or the punch
shown in
The middle portion 904 may support the tip 914 of the punch and be sized
and/or weighted according to production specifications. In various embodiments, the middle
portion is made of ferromagnetic material such as iron, martensitic steel, etc.
The at least one travel stop 906 may guide motion of the armature 910. At
least one travel stop may be configured to provide a range of motion as needed to produce the
magnet described herein. In various embodiments, the travel stop limits the armature from
traveling beyond a pre-definable location in either direction.
The spring 908 may assist the motion of the armature 910 and apply pressure
on a die such as the die of FIGS. 8A and 8B to complete a magnetic circuit in accordance
with a magnet production process such as the process of The spring may cause the
armature 910 to move. The motion of the spring may be limited by the at least one travel stop
906.
The spring loaded armature 910 moves along with the tip of the punch when it
is in contact with one of the stops in accordance with a magnet production process such as the
process of In various embodiments, the armature can slide relative to the rest of the
punch. In an at-rest position when the armature is separated from the die, the armature may
be spring loaded again the lower travel stop as shown.
The at least one coil 912 may energize the armature. In various embodiments,
the at least one coil induces a magnetic field through magnet powder provided in a die such
as the die of FIGS. 8A and 8B in accordance with the process of For example, the at
least one coil induces a magnetic field through the magnet powder. The induced magnetic
field during die pressing may cause sufficient flux in the magnet powder in the cavity to align
the powder particles in the desired formation. For example, the amount of flux is around 0.5
T to around 1.5 T. In some instances, the stronger the flux the more strongly powder particles
are aligned as they are locked in place during pressing. FIGS. 4-7 show example magnetic
field induced through the magnet powder.
The tip 914 may come in contact with magnet powder provided in a die such
as the die of FIGS. 8A and 8B in accordance with the process of For example, the tip
shapes and/or compresses the magnet powder. In some embodiments, the tip is made from
material of low magnetic permeability. In some embodiments, the tip is made from material
of high magnetic permeability. For example, the lightly shaded portion of the tip 914 is made
from a high permeability ferromagnetic material such as iron or steel, attached (e.g., brazed
or glued) to the darkly shaded portion which is made of high magnetic permeability carbide
such as high cobalt cemented tungsten carbide. The carbide on the end of the tip 914 may
reduce tool wear caused by the abrasive nature of the magnet powder. The shape of the
faying surface between the carbide and iron can be adjusted to improve the distribution of
magnetic flux in the magnet powder. The shape of the faying surface can also be adjusted to
reduce stress between the iron and carbide parts that may be induced during a pressing
process.
is a diagram of an embodiment of an assembly for producing a three
pole magnet. The assembly includes an upper punch 1002, a die 1004, and a lower punch
1008. An example of the upper punch is shown in An example of the die is shown in
FIGS. 8A and 8B. The die 1004 may be configured to receive magnet powder 1006 that
becomes a magnet (e.g., an un-magnetized block of material) in accordance with a magnet
production process such as the process of
In some embodiments, the darkly-shaded portion 1012 of the lower punch is
made from material of low magnetic permeability. In some embodiments, the portion 1012 is
made from material of high magnetic permeability. For example, the portion 1012 is made
from low cobalt carbide or high cobalt carbide. The choice of permeability of the lower
punch can affect the distribution of flux in the magnet powder during pressing. If a detent is
formed in the bottom of the magnet during pressing, a higher permeability carbide lower
punch may be used. If there is no detent, a low permeability carbide punch may be sufficient.
The lower punch may be adapted to move relative to the die and upper punch.
In some embodiments, the lower punch is fixed to ground and the other components of the
assembly move. In other embodiments, the die is fixed to ground and the other components
of the assembly move. In other embodiments, the upper punch, lower punch and die all move
with respect to the ground.
The armature 1010 of the upper punch 1002 may be spring loaded against the
die to complete a magnetic circuit. For example, in the armature is contact with the
die in the circled portion. This allows a magnetic field to be generated at substantially the
same time that pressure is applied to the magnet powder (e.g., allowing 304 and 306 of to occur substantially simultaneously).
Although the armature 1010 is shown as part of the upper punch here, in some
embodiments, the armature is instead part of (e.g., wrapped around) the lower punch 1008.
This may allow less wire to be used for the at least one coil 912 because the wires for the
coil(s) need not accommodate as much motion compared with the armature being provided in
the upper punch. In some embodiments, the armature is permanently attached to the die such
that there is no need for a spring or travel stops.
A is a diagram of an embodiment of a process to manufacture a three-
pole magnet. The diagram includes three sets of drawings, where each set shows a particular
view of the same assembly. A first set (1110.1, 1120.1, and 1130.1) shows a cross-section
view of an assembly performing a first portion of the process, a second set (1110.2, 1120.2,
and 1130.2) shows a cross-sectional isometric view of the assembly performing the first
portion of the process, and a third set (1110.3, 1120.3, and 1130.3) shows an isometric view
of the assembly performing the first portion of the process. Each of the drawings in the same
column correspond to a same time during the process. For example, 1110.1, 1110.2, and
1110.3 take place at the same time and the three separate drawings are provided as examples
to show different views of the assembly. An example process will now be discussed with
respect to 1110.1, 1120.1, and 1130.1.
1110.1 shows an initial state of the assembly. The example assembly shown
includes upper punch 1112, lower punch 1118, and die 1113. The assembly cooperates with
hopper 1116 to produce a three-pole magnet. In the initial state, upper punch 1112 and lower
punch 1118 are respectively positioned above and below the hopper 1116, ready to begin the
process of manufacturing a three-pole magnet. In some embodiments, previously-produced
green form 1114 is pushed out of the way when the hopper moves into its current position.
The green form 1114 was produced in a previous cycle. When the hopper 1116 shifts from
the left side of the drawing (not shown) to its current position shown in 1110.1, the green
form 1114 is pushed to the position shown in 1110.1. In some embodiments, the green form
then proceeds to a sintering oven (not shown).
In 1120.1, magnet powder fills a cavity 1124 of the die 1113. For example,
magnet powder 1128 from the hopper 1116 fills the die cavity. In some embodiments, the
lower punch moves down to allow the magnet powder to fill the die cavity. In some
embodiments, the die and table move up to allow the magnet powder to fill the die cavity.
1130.1 shows a state of the assembly in which die cavity 1124 contains an
appropriate amount of magnet powder and hopper 1116 slides out of the way to its current
position. In various embodiments, when the hopper 1116 slides from between the upper
punch and the lower punch out of the way, any excess powder in the vicinity of the die cavity
is scraped off. This may allow for fine control of the magnet powder provided to the die
cavity during the manufacturing process. In various embodiments, 1120.1 and 1130.1 are
examples of filling a die cavity with magnet powder (302) of
B is a diagram of an embodiment of a process to manufacture a three-
pole magnet. In various embodiments, the process shown in B occurs after the
process shown in A. The diagram includes three sets of drawings, where each set
shows a particular view of the same assembly. A first set (1140.1 and 1150.1) shows a cross-
section view of an assembly performing a first portion of the process, a second set (1140.2
and 1150.2) shows a cross-sectional isometric view of the assembly performing the first
portion of the process, and a third set (1140.3 and 1150.3) shows an isometric view of the
assembly performing the first portion of the process. Each of the drawings in the same
column correspond to a same time during the process. For example, 1140.1, 1140.2, and
1140.3 take place at the same time and the three separate drawings are provided as examples
to show different views of the assembly. An example process will now be discussed with
respect to 1140.1 and 1150.1.
In 1140.1, the upper punch 1112 is lowered such that a magnetic circuit is
closed. For example, the armature 1142 contacts the die 1113 to form the magnetic circuit. In
various embodiments, the lowering of the upper punch spring loads the armature 1142 against
the die 1113. In various embodiments, upon forming the magnetic circuit, at least one coil
1144 is energized to create a magnetic field. An example of an assembly for forming the
magnetic circuit is shown in . An example of a magnetic field initially created when
the magnetic circuit is closed and the at least one coil is energized is shown in FIGS. 4 and 6.
In various embodiments, magnet powder in the die cavity 1124 is compressed in the cavity
(e.g., shifted farther down the die cavity). For example, the lower punch 1118 is lowered. As
another example, the die 1113 and table move up to allow the powder to be compressed. In
various embodiments, 1140.1 is an example of inducing a magnetic field through the magnet
powder (304) of
In 1150.1, the upper punch 1112 and/or the lower punch 1118 are pressed to
apply pressure on the magnet powder in the die cavity 1124. For example, the upper and
lower punches are pressed together to reach a threshold pressure within the powder. The
threshold pressure (e.g., around 5,000 psi to 50,000 psi) is sufficient to cause the powder
particles to fuse together. In various embodiments, the result of applying pressure to the
magnet powder is a green form. The green form may be strong enough to hold its form when
the pressure is released. In some embodiments, the powder volume is reduced when it is
pressed into green form. For example, the powder volume is reduced by about a factor of two
when it is pressed into the green form. The arrows shown in 1150.1 are example directions of
applied force. Force may be applied in a downward direction by the upper punch, an upward
direction by the lower punch, or a combination of both directions. In various embodiments,
1150.1 is an example of applying pressure to the magnet powder to form a green form (306)
of
C is a diagram of an embodiment of a process to manufacture a three-
pole magnet. In various embodiments, the process shown in C occurs after the
process shown in B. The diagram includes three sets of drawings, where each set
shows a particular view of the same assembly. A first set (1160.1 and 1170.1) shows a cross-
section view of an assembly performing a first portion of the process, a second set (1160.2
and 1170.2) shows a cross-sectional isometric view of the assembly performing the first
portion of the process, and a third set (1160.3 and 1170.3) shows an isometric view of the
assembly performing the first portion of the process. Each of the drawings in the same
column correspond to a same time during the process. For example, 1160.1, 1160.2, and
1160.3 take place at the same time and the three separate drawings are provided as examples
to show different views of the assembly. An example process will now be discussed with
respect to 1160.1 and 1170.1.
In 1160.1, pressure is released on the green form 1162. This may allow the
green form to be removed from the die cavity. In various embodiments, 1160.1 is an example
of releasing pressure on the green form (308) of In this example, the upper punch
1112 is moved out of the way, but it is also possible to release pressure without moving the
upper punch out of the way. For example, the upper punch may be positioned as shown in
1140.1 of B without applying any pressure to the die cavity.
In 1170.1, the green form 1162 is removed from the die 1113. For example,
the green form is ejected by moving the lower punch 1118 up. As another example, the green
form is ejected by moving the die and table down. Following 1170.1, the green form may be
pushed out of the way by the hopper. An example of a green form being pushed out of the
way is the green form 1114 shown in 1110.1 of A. As described herein, the green
form may then proceed to a sintering oven to become solidified. For example, the green form
is sintered to make the block of material a solid magnet material.
In various embodiments, the procedures shown in FIGS. 11A-11C may be
repeated to produce green forms in sequence. It is also possible to provide a plurality of the
assemblies shown to produce green forms in parallel.
The magnet described here finds application in a variety of application
including magnet arrays and electric motors. A is a diagram of an embodiment of a
motor including an array of magnets according to an embodiment. The magnet array includes
at least one magnet produced according to techniques described here. A is an
exploded view of the motor. B is a cross-sectional exploded view of the motor. Here,
the example brushless motor includes a full flat circular array of magnets. The motor includes
an upper rotor housing 1202, an upper magnet array 1204, a stator 1206, a lower magnet
array 1208, a lower rotor housing 1212 and a plurality of bearings 1210.
The upper rotor housing 1202 and the lower rotor housing house 1212
respectively house the upper and lower rotors. In this example, the rotors are implemented by
the magnetic array described herein. The example upper rotor housing is shown with an
output shaft on top. The upper magnet array 1204 may have substantially all of its magnetic
field facing downwards. The lower magnet array 1208 may have substantially all of its
magnetic field facing upwards. The stator 1206 may include wire winding mounted to the
stator housing. For example, the stator may include a three phase litz wire winding mounted
to the stator housing. The plurality of bearings 1210 controls motion between the upper rotor
and the stator and the lower rotor and the stator.
is a diagram of an embodiment of a magnet array. In this example, the
magnet array is a flat circular array made up of a plurality of magnets. To illustrate a shape of
the individual magnets, some magnets 1306 are shown here lifted away from the array 1300.
Individual magnets may be of various shapes. In some embodiments, a magnet 1306 is
substantially a sector of a right cylindrical annulus, where a first surface is an upper surface
having a shape that is substantially circular or trapezoidal and a second surface and third
surface (substantially opposite each other and adjacent top the top surface) are flat
rectangular or non-circular surfaces. In some embodiments, a magnet 1306 is substantially a
right trapezoidal prism. In various embodiments, the magnets shown in are sintered
blanks that are capable of being magnetized in place.
In contrast to typical current techniques for making magnets, some of the
magnets described herein have shapeable magnetic fields. The techniques here allow for fine
control of the shape of the magnetic field. In addition, the magnets described here need not
have back iron or iron anywhere in the magnetic circuit of motor, which may improve
performance and reduce the cost, weight, and/or complexity of manufacturing the magnet.
The advantages of the magnets and magnet manufacturing techniques described here also
improve the magnet arrays, rotors, motors, and other machines in which they are used.
For example, a sintered blank (e.g., un-magnetized magnet) produced
according to the techniques described here can be used to generate a variety of types of
magnetized magnets. In one example use case, one sintered blank generates two different
types of magnets and is sufficient to produce a magnet array that performs similar to or better
than a Halbach array. By contrast, current magnet arrays typically use two types of sintered
blanks to yield three different types of magnets. Thus, using the techniques here reduces the
complexity and cost of manufacturing magnet arrays.
In addition, using a magnet described here for a magnet array can reduce the
number of magnets needed to form an array. In some embodiments, the number of magnets to
form an array is half as many as the number of magnets needed for a traditional Halbach
magnet array with four magnets per cycle. For example, instead of 308 magnets per array,
154 magnets are used in each array with each magnet being about twice as wide.
The sintered blanks described here are also compatible with co-curing
processes in which the magnets are magnetized in place after assembly into a desired
configuration. For example, magnet strength is not reduced because heating to assemble the
array (which causes magnets to lose strength) is performed prior to magnetization. Also,
conventional pick and place robots are compatible with magnet array manufacturing
processes using the magnets described here because bulky magnet carriers are unnecessary.
Although the foregoing embodiments have been described in some detail for
purposes of clarity of understanding, the invention is not limited to the details provided.
There are many alternative ways of implementing the invention. The disclosed embodiments
are illustrative and not restrictive.
Claims (13)
1. An array of magnets, comprising: first three-pole magnets and second three-pole magnets arranged in an array in which each of the first three-pole magnets is interfaced with an adjacent one or more of the second three-pole magnets; wherein each of the first three-pole magnets comprises: a first magnet first magnetic pole having a first magnetic polarity at a first magnet first surface of the first three-pole magnet; a first magnet second magnetic pole having a second magnetic polarity at a first magnet second surface of the first three-pole magnet, wherein the second magnetic polarity is opposite the first magnetic polarity, and wherein the first magnet second surface is adjacent to and at least partly orthogonal to the first magnet first surface; and a first magnet third magnetic pole having the second magnetic polarity at a first magnet third surface of the first three-pole magnet, wherein the first magnet third surface is adjacent to the first magnet first surface and disposed on a substantially opposite side of the first three-pole magnet relative to the first magnet second surface; wherein: each of the first three-pole magnets have first magnet first magnetic flux lines and first magnet second magnetic flux lines; the first magnet first magnetic flux lines intersect the first magnet second surface orthogonal to the first magnet second surface; and the first magnet second magnetic flux lines intersect the first magnet third surface orthogonal to the first magnet third surface; wherein each of the second three-pole magnets comprises: a second magnet first magnetic pole having the second magnetic polarity at a second magnet first surface of the second three-pole magnet; a second magnet second magnetic pole having the first magnetic polarity at a second magnet second surface of the second three-pole magnet, wherein the second magnet second surface is adjacent to and at least partly orthogonal to the second magnet first surface; and a second magnet third magnetic pole having the first magnetic polarity at a second magnet third surface of the second three-pole magnet, wherein the second magnet third surface is adjacent to the second magnet first surface and disposed on a substantially opposite side of the second three-pole magnet relative to the second magnet second surface; and wherein: each of the second three-pole magnets have second magnet first magnetic flux lines and second magnet second magnetic flux lines; the second magnet first magnetic flux lines intersect the second magnet second surface orthogonal to the second magnet second surface; the second magnet second magnetic flux lines intersect the second magnet third surface orthogonal to the first magnet third surface.
2. The array of magnets of claim 1, wherein: for each respective instance of the first three-pole magnets, substantially all magnetic flux passing through the respective instance of the first three-pole magnets passes through the first magnet first surface of the respective instance of the first three-pole magnets; and for each respective instance of the second three-pole magnets, substantially all magnetic flux passing through the respective instance of the second three-pole magnets passes through the second magnet first surface of the respective instance of the second three- pole magnets.
3. The array of magnets of claim 1, wherein the first magnet first surface of each of the first three-pole magnets and the second magnet first surface of each of the second three-pole magnets are coplanar.
4. The array of magnets of claim 1, wherein at least one of the first three-pole magnets and the second three-pole magnets is a right prism.
5. The array of magnets of claim 1, wherein at least one of the first three-pole magnets and the second three-pole magnets is a right trapezoidal prism.
6. The array of magnets of claim 1, wherein: at least one of the first three-pole magnets or the second three-pole magnets is a sector of a right cylindrical annulus.
7. The array of magnets of claim 1, wherein: the first magnetic polarity is a north magnetic polarity; the second magnetic polarity is a south magnetic polarity; and all of the first magnet first surfaces and the second magnet first surfaces face the same direction.
8. A brushless motor comprising the array of magnets of claim 1.
9. The array of magnets of claim 1, wherein the first magnet first surface has a substantially circular sector shape; and the second magnet first surface has a substantially circular sector shape.
10. The array of magnets of claim 1, wherein: the first magnet first surface has a perimeter with a substantially trapezoidal shape; the second magnet first surface has a perimeter with a substantially trapezoidal shape.
11. The array of magnets of claim 1, wherein: at least one of the first three-pole magnets further includes a first magnet fourth surface substantially opposite the first magnet first surface and the first magnet fourth surface does not include a magnetic pole; and at least one of the second three-pole magnets further includes a second magnet fourth surface substantially opposite the second magnet first surface and the second magnet fourth surface does not include a magnetic pole.
12. The brushless motor of claim 8, further comprising: a rotor that includes the array of magnets; and a stator substantially adjacent to the rotor.
13. A lift fan assembly comprising the brushless motor of claim 12.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
NZ767174A NZ767174B2 (en) | 2017-11-16 | A method of manufacturing, and an assembly for producing, a magnet |
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US15/398,300 US10586639B2 (en) | 2017-01-04 | 2017-01-04 | Array of three pole magnets |
US15/398,300 | 2017-01-04 | ||
PCT/US2017/062084 WO2018128715A1 (en) | 2017-01-04 | 2017-11-16 | Array of three pole magnets |
Publications (2)
Publication Number | Publication Date |
---|---|
NZ753663A NZ753663A (en) | 2021-03-26 |
NZ753663B2 true NZ753663B2 (en) | 2021-06-29 |
Family
ID=
Similar Documents
Publication | Publication Date | Title |
---|---|---|
US11069464B2 (en) | Method and assembly for producing a magnet | |
US20180229264A1 (en) | Method for making a component for use in an electric machine | |
US7740714B2 (en) | Method for preparing radially anisotropic magnet | |
CN1998125A (en) | High field voice coil motor | |
JP2006086319A (en) | Ring type sintered magnet | |
US7675202B1 (en) | Isotropic ring magnet linear voice coil motor | |
JP6308205B2 (en) | Method for manufacturing anisotropic magnet, method for manufacturing anisotropic soft magnetic material, and method for manufacturing rotor of rotating electrical machine | |
CN103155720A (en) | Improved multipole magnet | |
JP2003257762A (en) | Ring magnet, manufacturing method therefor, rotor, rotating machine, magnetic field generating apparatus therefor, and ring magnet manufacturing apparatus | |
CN106876086B (en) | Multi-magnetized single permanent magnet, magnetic circuit, mold and manufacturing method thereof | |
JP2006304472A (en) | Ring magnet, and manufacturing apparatus and manufacturing method thereof | |
TWI637583B (en) | Axial gap rotary electric machine | |
CN105280324B (en) | The manufacturing method of magnet unit and magnet unit | |
WO2012033202A1 (en) | Arched magnet and magnetic field molding die | |
JP4425682B2 (en) | Mold, molding machine, method and magnet obtained for manufacturing anisotropic magnet | |
CN102891003A (en) | Radial permanent magnet orienting and magnetizing device of concentric ring opposed coil type | |
NZ753663B2 (en) | Array of three pole magnets | |
NZ767174B2 (en) | A method of manufacturing, and an assembly for producing, a magnet | |
JP2009111418A (en) | Die, molding machine and method used for manufacturing anisotropic magnet, and magnet manufactured thereby | |
JP2860858B2 (en) | Mold for magnetic powder molding | |
JP6750373B2 (en) | Moving coil type voice coil motor | |
JP2012119698A (en) | Manufacturing apparatus of radial anisotropic ring magnet | |
KR101071424B1 (en) | Method for manufacturing of radial sintered magnet having anisotropic | |
JPS6358033B2 (en) | ||
JP4926834B2 (en) | Radial anisotropic ring magnet manufacturing equipment |