U.S. patent application number 15/468653 was filed with the patent office on 2017-09-28 for brushroll for vacuum cleaner.
The applicant listed for this patent is BISSELL Homecare, Inc.. Invention is credited to Gary A. Kasper, Jeffrey A. Scholten.
Application Number | 20170273523 15/468653 |
Document ID | / |
Family ID | 59897294 |
Filed Date | 2017-09-28 |
United States Patent
Application |
20170273523 |
Kind Code |
A1 |
Kasper; Gary A. ; et
al. |
September 28, 2017 |
BRUSHROLL FOR VACUUM CLEANER
Abstract
A brushroll for a vacuum cleaner includes a brush dowel having a
plurality of bristles and a drive motor within the brush dowel for
rotating the brush dowel in a first direction of rotation, wherein
an armature and motor shaft of the drive motor counter-rotates in a
second direction of rotation.
Inventors: |
Kasper; Gary A.; (Grand
Rapids, MI) ; Scholten; Jeffrey A.; (Ada,
MI) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
BISSELL Homecare, Inc. |
Grand Rapids |
MI |
US |
|
|
Family ID: |
59897294 |
Appl. No.: |
15/468653 |
Filed: |
March 24, 2017 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
62313439 |
Mar 25, 2016 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
A47L 9/1616 20130101;
A47L 9/0455 20130101; A47L 11/302 20130101; A47L 9/0411 20130101;
A47L 9/0438 20130101; A47L 9/0477 20130101; A47L 11/4041 20130101;
A47L 9/1608 20130101; A47L 11/4086 20130101; A47L 5/26 20130101;
A47L 9/1683 20130101; A47L 5/362 20130101 |
International
Class: |
A47L 9/04 20060101
A47L009/04; A47L 9/16 20060101 A47L009/16; A47L 11/30 20060101
A47L011/30; A47L 11/40 20060101 A47L011/40; A47L 5/26 20060101
A47L005/26; A47L 5/36 20060101 A47L005/36 |
Claims
1. A brushroll for a vacuum cleaner, comprising: a brush dowel
configured to rotate about a longitudinal axis in a first
direction; a plurality of bristles extending outwardly from the
brush dowel; and a drive motor within the brush dowel for rotating
the brush dowel about the longitudinal axis, the drive motor
comprising: a stator mounted to an inner portion of the brush dowel
for rotation with the brush dowel about the longitudinal axis; a
motor shaft extending within the brush dowel and defining the
longitudinal axis; an armature mounted on the motor shaft and
rotatable relative to the stator; and a commutator mounted on the
motor shaft and rotatable with the armature, relative to the
stator; and a mechanical coupling between the drive motor and the
dowel comprising a planetary gear assembly; wherein the armature,
commutator, and motor shaft are configured to rotate within the
dowel about the longitudinal axis in a second direction, opposite
the first direction.
2. The brushroll of claim 1, wherein the stator comprises a
plurality of magnets mounted to an interior surface of the brush
dowel for rotation with the brush dowel.
3. The brushroll of claim 2, wherein the plurality of magnets
comprises at least one pair of opposing magnets, wherein the
opposing magnets have opposite polarity.
4. The brushroll of claim 2, wherein the interior surface of the
brush dowel comprises a plurality of recesses, and wherein the
magnets are received within the recesses.
5. The brushroll of claim 4, wherein the plurality of bristles are
offset from the recesses.
6. The brushroll of claim 1, wherein the mechanical coupling is
configured to counter-rotate the brush dowel and stator relative to
the armature at a first rotational speed less than a second
rotation speed of the armature and motor shaft.
7. The brushroll of claim 1, wherein planetary gear assembly
reduces the rotational speed of the brush dowel compared to the
motor shaft.
8. The brushroll of claim 1, wherein the planetary gear assembly
comprises a sun gear mounted on the motor shaft, a ring gear fixed
with the brush dowel, and a plurality of planet gears engaged with
the sun gear and the ring gear.
9. The brushroll of claim 8, wherein the plurality of planet gears
rotate about respective planet gear axes that are fixed in space
relative to the brush dowel and the motor shaft.
10. The brushroll of claim 8, wherein the planet gear axes of the
plurality of planet gears are parallel to and offset from the
longitudinal axis.
11. The brushroll of claim 8, wherein the planetary gear assembly
further comprises a carrier for the plurality of planet gears,
wherein the carrier is stationary such that the plurality of planet
gears rotate in fixed positions while the sun gear and ring gear
rotate in opposite directions.
12. The brushroll of claim 1, wherein the drive motor further
comprises motor brushes configured to contact the commutator as the
commutator rotates.
13. The brushroll of claim 12, wherein the motor brushes are
supported by a first bearing holder provided on one end of the
brush dowel and mounted to the motor shaft.
14. The brushroll of claim 13, wherein the first bearing holder
receives bearings on which the brush dowel rotates relative to the
motor shaft.
15. The brushroll of claim 13, and further comprising a second
bearing holder provided on an opposite end of the brush dowel and
mounted to the motor shaft, wherein the second bearing holder
receives bearings on which the brush dowel rotates relative to the
motor shaft.
16. The brushroll of claim 15, wherein the planetary gear assembly
comprises a plurality of planet gears and a carrier for the
plurality of planet gears, and wherein the carrier is integrally
formed with or provided on the second bearing holder.
17. The brushroll of claim 12, wherein the commutator comprises a
plurality of commutator bars and the armature comprises a plurality
of wire slots, wherein the armature is wired so that the wire slots
are incrementally advanced ahead of the commutator bars in an
advancing pattern.
18. The brushroll of claim 17, wherein the motor brushes are
separated by an angular distance relative to the longitudinal axis,
and wherein the armature is wired so that the advancing pattern
repeats when the brush dowel has rotated a number of degrees equal
to the angular distance.
19. The brushroll of claim 1, wherein the planetary gear assembly
comprises a -3:1 gear ratio, the stator comprises six field
magnets, and the drive motor comprises two motor brushes configured
to contact the commutator as the commutator rotates.
20. A vacuum cleaner comprising: a suction nozzle inlet; a suction
source in fluid communication with the suction nozzle inlet for
generating a working airstream; a separating and collection
assembly for separating and collecting debris from the working
airstream; a brushroll adjacent the suction nozzle inlet and
comprising: a brush dowel configured to rotate about a longitudinal
axis in a first direction; a plurality of bristles extending
outwardly from the brush dowel; and a drive motor within the brush
dowel for rotating the brush dowel about the longitudinal axis, the
drive motor comprising: a stator mounted to an inner portion of the
brush dowel for rotation with the brush dowel about the
longitudinal axis; a motor shaft extending within the brush dowel
and defining the longitudinal axis; an armature mounted on the
motor shaft and rotatable relative to the stator; and a commutator
mounted on the motor shaft and rotatable with the armature,
relative to the stator; and a mechanical coupling between the drive
motor and the brush dowel comprising a planetary gear assembly;
wherein the armature, commutator, and motor shaft are configured to
rotate within the brush dowel about the longitudinal axis in a
second direction, opposite the first direction.
Description
CROSS-REFERENCE TO RELATED APPLICATION(S)
[0001] This application claims the benefit of U.S. Provisional
Patent Application No. 62/313,439, filed Mar. 25, 2016, which is
incorporated herein by reference in its entirety.
BACKGROUND
[0002] Conventional brushrolls for vacuum cleaners have been driven
by an external motor coupled to the brushroll via a drive belt. The
external motor may be a dedicated brushroll motor, or may be the
same motor used to generate suction force at the suction nozzle
inlet opening of the vacuum cleaner.
[0003] The conventional belt-driven configuration results in many
undesirable effects, including: loss of brushroll rotation due to
broken or stretched-out belts, melted end caps, hair wrap in the
belt area; reduced or impeded suction in the belt area,
intermittent brushing; obstructions in the air path created by the
belt and motor; reduced edge cleaning performance; excessive noise;
bearing failure due to high belt loads; increased costs
necessitated by the motor and belt parts; and frequent and costly
repairs.
[0004] FIG. 1 shows a cross-sectional view of a prior art DC motor
assembly 10, and identifies several key components mounted in a
common configuration within a housing 12. An end cap 14 closes one
end of the housing 12, and motor terminals 16 extend through the
end cap 14 to couple the motor with a source of DC current and
ground. In the electric motor, an armature (rotor) 18 is a wound
wire coil or permanent magnet, mounted on a motor shaft 20 that
rotates when exposed to magnetic flux from a stator 22 surrounding
the armature 18. The windings 24 of the armature 18 illustrated
herein are metal wires wrapped into coils to form magnetic poles
when energized with electrical current. The stator 22 is a
stationary portion of the electric motor 10 within which the
armature 18 rotates. The stator 22 can comprise either permanent
magnets or windings, which are typically referred to as field
magnets or field coils; in the illustrates embodiment the stator 22
comprises permanent magnets. A core of the armature 18 commonly
comprises a plurality of metal sheets referred to as armature
laminations 26 or an armature lamination stack. The stator 22 and
armature 18 generate interacting magnetic forces or magnetic flux
fields, which generate torque on the armature 18, which in turn
rotates the motor shaft 20. Bearings 28 mount the shaft 20 within
the housing 12, allowing the shaft 20 to spin smoothly.
[0005] The commutator 30 is a moving portion of a rotary electrical
switch that supplies current from a power source to the armature 18
via the motor terminals 16. The commutator 30 reverses the current
between the armature 18 and the external power supply circuit in
regular intervals to maintain uniform torque for rotating the
armature 18 smoothly. The commutator 30 can comprise a cylinder
with multiple metal bars or contact segments configured to make
sliding contact with electrical contact brushes 32 that press
against the successive segments of the commutator 30 as it
rotates.
[0006] Attempts have been made in the past to incorporate a DC
motor into a brush dowel for a vacuum cleaner (also known as an
inside-out motor brush dowel) with limited success. In these prior
art designs, the brush motor assembly can generally comprise an
outer cylindrical housing or "can" for mounting various components,
including a stator and an armature disposed inside the stator on a
motor shaft, the shaft being rotatably mounted on bearings within
the housing. A commutator is also mounted on the motor shaft and
rotates with the armature, relative to the stator. The commutator
is mounted in sliding register with stationary electrical contact
brushes, which deliver power to the commutator from a power supply
as the commutator rotates together with the shaft.
[0007] The key challenges with this motor configuration have been
attaining the desired torque and speed necessary for adequate
cleaning while maintaining the brush diameter within reasonable
dimensional limits so as to introduce minimal impacts on vacuum
cleaner foot architecture and performance. In one example, the
brush roll diameter is less than about 4.0 inches and preferably
less than 3.0 inches. Many conventional, externally-driven brush
dowels can typically have diameters of about 1.00-3.0 inches, for
example. Making the brush dowel an inside-out motor brush dowel
with an outer diameter similar to an externally-driven motor has
been attempted, but cleaning performance has been less than
acceptable because the motor torque is too low and brush speed is
too high. Limited success has been achieved by inserting a fixed
permanent magnet foot motor into the dowel and using a planetary
gear train to drive the brush. However, this configuration
typically increases the dowel diameter and can cause the brush to
run at low speed or with low torque. An increased brush dowel
diameter can enlarge the height of the foot structure including the
brush chamber, which can hinder or limit access to confined spaces,
such as under cabinet toe kicks and various furniture. The costs
associated with these previously attempted configurations can also
be relatively high compared to a conventional externally-driven
brush roll configuration.
BRIEF SUMMARY
[0008] In one aspect, the invention relates to a brushroll for a
vacuum cleaner, having a brush dowel configured to rotate about a
longitudinal axis in a first direction, a plurality of bristles
extending outwardly from the brush dowel, and a drive motor within
the brush dowel for rotating the brush dowel about the longitudinal
axis, wherein an armature, commutator, and motor shaft of the drive
motor are configured to rotate within the dowel about the
longitudinal axis in a second direction, opposite the first
direction.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] In the drawings:
[0010] FIG. 1 is a cross-sectional view of a prior art DC motor
assembly;
[0011] FIG. 2 is a schematic view of a vacuum cleaner;
[0012] FIG. 3 is a perspective view of a vacuum cleaner base;
[0013] FIG. 4 is an exploded view of the vacuum cleaner base of
FIG. 2;
[0014] FIG. 5 is a partially exploded view of a brushroll of the
vacuum cleaner base of FIG. 2;
[0015] FIG. 6 is a cross-sectional view of the brushroll through
line VI-VI of FIG. 3, with middle sections of the brushroll removed
for clarity;
[0016] FIG. 7 is a cross-sectional view of the brushroll through
line VII-VII of FIG. 4;
[0017] FIG. 8 is a cross-sectional view of the brushroll through
line VII-VII of FIG. 4;
[0018] FIG. 9A-9G are schematic views of a first embodiment of an
armature winding diagram for a brushroll ;
[0019] FIG. 10 is a schematic view of a second embodiment of an
armature winding diagram for a brushroll;
[0020] FIG. 11 is a diagram of a winding pattern for the armature
winding diagram of FIG. 10; and
[0021] FIG. 12A-12G are schematic views of a third embodiment of an
armature winding diagram for a brushroll.
DESCRIPTION OF EMBODIMENTS OF THE INVENTION
[0022] The invention generally relates to a vacuum cleaner
brushroll, wherein the brushroll incorporates a motor; the vacuum
cleaner may be in the form of an upright vacuum cleaner, a
hand-held vacuum cleaning device, an autonomous robotic sweeping or
vacuum cleaning device, or as an apparatus having a floor nozzle or
a hand-held accessory tool connected to a canister or other
portable device by a vacuum hose or conduit. Additionally, in some
embodiments of the invention the vacuum cleaner can have fluid
delivery capability, including applying liquid or steam to the
surface to be cleaned, and/or fluid extraction capability.
[0023] Examples of a suitable suction cleaners or vacuum cleaners
in which the various embodiments of the brushroll disclosed herein
can be used are disclosed in U.S. Pat. No. 7,377,007, issued May
27, 2008, U.S. Pat. No. 7,346,428 issued Mar. 18, 2008, and U.S.
Patent Application publication No. 2012/0304416, published Dec. 6,
2012, for example, which are incorporated herein by reference in
their entirety. Aspects of the invention may also be incorporated
into vacuum cleaners having a fluid delivery system and/or a fluid
recovery system.
[0024] FIG. 2 is shown a schematic view of one example of a vacuum
cleaner 40 in which a brushroll according to an embodiment of the
invention may be provided. The vacuum cleaner 40 is shown herein as
an upright or stick-type vacuum cleaner, with a housing comprising
an upper unit 42 coupled with a foot or base 44 adapted to be moved
over a surface to be cleaned S. The vacuum cleaner 40 can
alternatively be configured as a canister-type vacuum cleaner or a
hand-held vacuum cleaner.
[0025] The vacuum cleaner 40 can include a vacuum collection system
for creating a partial vacuum to suck up debris (which may include
dirt, dust, soil, hair, and other debris) from the surface to be
cleaned S and collecting the removed debris in a space provided on
the vacuum cleaner 40 for later disposal. Furthermore, the vacuum
cleaner 40 can additionally be configured to distribute a fluid
and/or to extract a fluid, where the fluid may for example be
liquid or steam.
[0026] The upper unit 42 is pivotally mounted to the base 44 for
movement between an upright storage position, shown in FIG. 2, and
a reclined use position (not shown) by a coupling joint. The vacuum
cleaner 40 can be provided with a detent mechanism, such as a pedal
pivotally mounted to the base 44, for selectively releasing the
upper unit 42 from the storage position to the use position. The
details of such a detent pedal are known in the art, and will not
be discussed in further detail herein.
[0027] The upper unit 42 includes a suction source 46 in fluid
communication with the base 44 for generating a working airstream
and a separating and collection assembly 48 for separating and
collecting debris (which can be solid, liquid, or a combination
thereof) from the working airstream for later disposal. The upper
unit 42 further includes a handle 58 to facilitate movement of the
vacuum cleaner 40 by a user. The handle 58 may further comprise a
handle grip 62.
[0028] In one configuration illustrated herein, the collection
assembly 48 can include a cyclone separator 52 for separating
contaminants from a working airstream and a removable debris cup 54
for receiving and collecting the separated contaminants from the
cyclone separator 52. The cyclone separator 52 can have a single
cyclonic separation stage, or multiple stages. In another
configuration, the collection assembly 48 can include an integrally
formed cyclone separator 52 and debris cup 54, with the debris cup
54 being provided with a structure, such as a bottom-opening debris
door, for contaminant disposal. It is understood that other types
of collection assemblies 48 can be used, such as a centrifugal
separator, a bulk separator, a filter bag, or a water-bath
separator. The upper unit 42 can also be provided with one or more
additional filters 50 upstream or downstream of the separating and
collection assembly 48 or the suction source 46.
[0029] The suction source 46, such as a motor/fan assembly, is
provided in fluid communication with the separating and collection
assembly 48, and can be positioned downstream or upstream of the
separating and collection assembly 48. The suction source 46 can be
electrically coupled to a power source 64, such as a battery or by
a power cord plugged into a household electrical outlet. A suction
power switch 66 disposed between the suction source 46 and the
power source 64 can be selectively closed by the user upon pressing
a vacuum power button, thereby activating the suction source 46. As
shown herein, the suction source 46 is downstream of the separating
and collection assembly 48 for a `clean air` system; alternatively,
the suction source 46 can be upstream of the separation and
collection assembly 48 for a `dirty air` system.
[0030] The base 44 is in fluid communication with the suction
source 46 for engaging and cleaning the surface to be cleaned S.
The base 44 includes a base housing 68 having a suction nozzle
inlet 70 at least partially disposed on the underside and front of
the base housing 68. The base housing 68 can secure an agitator 72
within the base 44 for agitating debris on the surface to be
cleaned S so that the debris is more easily ingested into the
suction nozzle inlet 70. The agitator 72 illustrated herein is a
rotatable brushroll positioned within the base 44 adjacent the
suction nozzle inlet 70 for rotational movement about an axis
X.
[0031] The vacuum cleaner 40 can be used to effectively clean the
surface to be cleaned S by removing debris (which may include dirt,
dust, soil, hair, and other debris) from the surface to be cleaned
S in accordance with the following method. The sequence of steps
discussed is for illustrative purposes only and is not meant to
limit the method in any way as it is understood that the steps may
proceed in a different logical order, additional or intervening
steps may be included, or described steps may be divided into
multiple steps, without detracting from the invention.
[0032] To perform vacuum cleaning, the suction source 46 is coupled
to the power source 64 and draws in debris-laden air through the
suction nozzle inlet 70 and into the separating and collection
assembly 48 where the debris is substantially separated from the
working air. The air flow then passes through the suction source
46, and through any optional filters 50 positioned upstream and/or
downstream from the suction source 46, prior to being exhausted
from the vacuum cleaner 40. During vacuum cleaning, the agitator 72
can agitate debris on the surface to be cleaned S so that the
debris is more easily ingested into the suction nozzle inlet 70.
The separating and collection assembly 48 can be periodically
emptied of debris. Likewise, the optional filters 50 can
periodically be cleaned or replaced.
[0033] FIGS. 3-4 show the vacuum cleaner base 44 and the brushroll
72 mounted in the base 44. For purposes of description related to
the figures, the terms "upper," "lower," "right," "left," "rear,"
"front," "vertical," "horizontal," "inner," "outer," and
derivatives thereof shall relate to the invention as oriented in
FIG. 3 from the perspective of a user behind base 44, which defines
a rear of the vacuum cleaner. However, it is to be understood that
the invention may assume various alternative orientations, except
where expressly specified to the contrary.
[0034] The base housing 68 includes an upper cover 74 and a lower
sole plate 76 enclosing the underside of the cover 74 to form a
brushroll chamber 78 therebetween at a forward end of the base 44.
The brushroll chamber 78 contains the brushroll 72, and is provided
adjacent to the nozzle inlet 70. The nozzle inlet 70 is provided at
a forward portion of the sole plate 76. Wheels 80 are secured to
the base 44 for moving the base 44 over a surface to be
cleaned.
[0035] FIG. 5 is a partial view of the brushroll 72. In a first
embodiment, the brushroll 72 comprises a brush dowel 82 tufted with
bristles 84 and an internal or built-in drive motor 86. The brush
dowel 82 is a hollow cylindrical member with an exterior surface 88
from which the bristles 84 project and an interior surface 90
defining the hollow space within the cylindrical member. Field
magnets 92 can be provided on the interior surface 90 to define a
stator 94 for driving an armature 96 of the motor 86. In one
example, recesses 93 for mounting the field magnets 92 can be
provided on the interior surface 90.
[0036] The armature 96 can be manufactured from a stack of armature
laminations or as a single piece of advanced particulate material.
The field magnets 92 of the present embodiment comprise permanent
magnets, and the armature 96 comprises electromagnetic wire coils.
However, the stator 94 can alternatively comprise an electromagnet
with a metal core and wire windings and/or the armature 96 can
comprise a permanent magnet.
[0037] Unlike a conventional DC motor in which the stator is fixed
and stationary with respect to a rotating armature, here, the
stator 94 is carried by the brush dowel 82 and configured to rotate
relative to the armature 96, which counter-rotates in an opposite
direction. The brush dowel 82 and stator 94 formed therein rotate
around the armature 96 in a first direction, which is opposite to
the rotational direction of the armature 96 and attached motor
shaft 98 and commutator 100. The commutator 100 is also mounted on
the motor shaft 98 and rotates with the armature 96, relative to
the stator 94.
[0038] A mechanical coupling is provided between the drive motor 86
and dowel 82 for transmitting driving force from the motor 86 to
the dowel 82. The mechanical coupling can be configured to
counter-rotate the dowel 82, and thus the stator 94, relative to
the armature 96 at a rotational speed less than that of the
armature 96 and motor shaft 98.
[0039] Referring to FIGS. 5-6, the motor shaft 98 is an elongated
shaft that extends through the center of the dowel 82 and defines
the axis about which the brushroll 72 rotates. A bearing holder 102
is mounted on both ends of the shaft 98 and fixed to the base
housing 68. The bearing holders 102 receive bearings 104 and, in
operation, the dowel 56 rotates relative to the base housing 68 on
the bearings 104. In other embodiments, the motor shaft 98 may not
extend to both ends of the dowel 82, but rather may couple with one
of the bearing holders 102, while a separate shaft is provided at
the opposite end of the dowel 82 and coupled with the other bearing
holder 102.
[0040] In one example, the mechanical coupling between the armature
96 and stator 94 can be provided at one end of the motor shaft 98,
adjacent one of the bearing holders 102, while the commutator 100
can be provided at the opposite end of the motor shaft 98, adjacent
the other bearing holder 102. The commutator 100 can comprise a
cylinder with multiple metal bars or contact segments configured to
make sliding contact with electrical contact brushes 105 that press
against the successive segments of the commutator 100 as it
rotates. The brushes 105 can be supported by the bearing holder 102
provided at the end of the motor shaft 98 with the commutator 100,
with the brushes 105 in contact with the commutator.
[0041] Referring to FIGS. 6-7, in one example, the brush dowel 82
and stator 94 are driven by the armature 96 through a mechanical
coupling comprising a planetary gear assembly or set 106. The
planetary gear set 106 includes a sun gear 108 mounted to the motor
shaft 98, in addition to the armature 96 and commutator 100, and
multiple planet gears 110 that rotate around the sun gear 108. A
plate or carrier 112 that holds the planet gears 110 is affixed to
the end of the base housing 68, thereby fixing the axes 114 of the
planet gears 110 in space. The carrier 112 can be integrally formed
with one of the bearing holders 102, such that the axes 114 are
fixed directly with the bearing holder 102, or can be a separate
component provided on or otherwise attached to the bearing holder
102. The axes 114 are parallel to and offset from the axis of
rotation defined by the motor shaft 98. A ring gear 116 also
supports the planet gears 110 and is fixed to the brush dowel 82.
Thus, the carrier 112 for the planet gears 110 is held fixed with
the base housing 68, while the sun and ring gear 108, 116 spin in
opposite directions with the brushroll 72. In one example, the sun
gear 108 can comprise 16 teeth, the planet gears 110 can comprise
16 teeth and the ring gear 116 can comprise 48 teeth. Because the
planetary gear carrier 112 is fixed and the sun gear 108 is the
input, the gear ratio in this instance can be calculated by using
the formula -R/S where R is the number of teeth of the ring gear
and S is the number of teeth of the sun gear, resulting in a gear
reduction ratio of -3:1. This configuration allows the interior
assembly including the armature 96 and motor shaft 98 to rotate at
high speed in one direction, while the assembly including the brush
dowel 82 and stator 94 counter-rotates at a slower speed in the
opposite direction. Other numbers of teeth for the gears 108, 110,
116 are possible, and may result in a gear reduction ratio of -3:1,
or another gear reduction ratio.
[0042] Referring to FIG. 8, this configuration also allows the
outer diameter D of the brushroll 72 to be maintained within
reasonable dimensional limits of less than about four inches and
preferably between 1.5 to 3.0 inches, for example, while
maintaining adequate torque to provide acceptable cleaning
performance. Reasonable dimensional limits are achieved by mounting
the field magnets 92 within recesses 93 formed on the inside of the
dowel 82 such that the magnets 92 rotate together with the dowel
82. The recesses 93 may be deep enough so that the field magnets 92
are flush with the interior surface 90 of the dowel 82, as shown in
FIG. 8. Alternatively, the field magnets 92 may project beyond the
interior surface 90 of the dowel 82.
[0043] The bristles 84 may advantageously be offset from the
magnets 92 and recesses 93 and may be set between the magnets 92.
It is noted that the thickness of the outer dowel wall, between the
exterior and interior surfaces 88, 90, is reduced locally around
the perimeter of the dowel 82 at the magnet mounting recesses 93.
Therefore, rather than tuft bristles 84 into a thinned-out dowel
wall section behind a magnet mounting recess 93, the bristles 84
can be tufted into thicker dowel wall sections between the
thinned-out wall sections. In one example, the bristles 84 can be
tufted into thicker dowel wall sections which are offset 45-90
degrees from the magnets 92 and recesses 93. Thus, the portion of
brush dowel wall receiving a bristle tuft anchor can be thicker,
which provides a more robust overall brush structure.
[0044] As shown in FIG. 5, in one embodiment, the bristles 84 can
be arranged in multiple tufted rows that wrap helically around the
brush dowel 82. In this case, the magnets 92 and recesses 93 may
also extend helically within the interior of the brush dowel 82,
offset from the helical rows of bristles 84. Other tufting patterns
can likewise result in different orientations for the magnets 92
and recesses 93 in order to maintain the offset between the
bristles 84 and the recesses 93.
[0045] There are several advantages of the first embodiment of the
brushroll 72 arising from the various features described herein.
For example, for the brushroll 72 of the first embodiment, the
effective diameter of the motor 86 can be much larger than that of
a fixed motor (i.e. a motor with a fixed/stationary stator) mounted
within a brushroll, and thus can generate an increased torque. Yet
another advantage arising from the various features of the
brushroll 72 of the first embodiment is that the armature 96 is
connected to the brush dowel 82 through the planetary gear assembly
106, which provides a gear reduction resulting in lower brush
speeds (relative to the armature speed) and higher torque levels
compared to a brushroll having an internal motor without a gear
reduction. Still another advantage arising from the various
features of the brushroll 72 of the first embodiment is that
smaller diameter, less costly bearings 104 can be used, in
comparison to larger diameter bearings that are required for the
fixed stator motor in dowel arrangement. Still another advantage
arising from the various features of the brushroll 72 of the first
embodiment is that alignment of all components is easily maintained
since the components are assembled coaxially within the brush dowel
82.
[0046] In a second embodiment of the invention, a particular
communication and wiring configuration can be provided for the
brushroll 72. The commutation of the armature 96 for the brushroll
72 of the first embodiment presents a particular challenge. A
standard commutation arrangement, comprising brushes mounted in a
fixed position relative to the stator, is not desirable because for
the brushroll 72 described herein, the stator 94 rotates with the
brush dowel 82. So, incorporating a standard commutation
arrangement would require the brushes 105 to rotate around the
commutator 100 in unison with the stator/brush dowel in order to
maintain the magnetic pole positions of the armature 96 in sync
with the magnetic poles of the field magnets 92. Rotating the motor
brushes 105 relative to the commutator 100 would also cause
electrical connection problems. For instance, centrifugal forces
acting on the rotating brushroll 72 could pull the brushes 105
outwardly, away from the commutator 100, thereby breaking the
electrical connection therebetween.
[0047] Alternatively, electronic brushless commutation is also not
desirable with the present invention because the field magnets 92
and armature 96 counter-rotate relative to each other. This
configuration would require the armature switching windings to be
connected through sliding electric contacts, which are undesirable
due to reliability concerns.
[0048] Therefore, a new commutation configuration is needed to
allow the electrical connections of the rotating armature 96 to
"run ahead" or index ahead relative to the rotating commutator bars
so that the armature poles remain in sync with the counter-rotating
field magnets 92. This presents an unusual challenge because the
electrical connection point between the commutator 100 and armature
96 must periodically index rearwardly or "step back" while
simultaneously maintaining timing and remaining in sync with the
changing poles of the rotating field magnets 92.
[0049] The commutation arrangement can be addressed a few different
ways. However, in all instances, it is necessary to increase the
number of poles in the field to a number greater than two poles,
which is the quantity typically present in a conventional permanent
magnet motor.
[0050] In one configuration, a first and second motor brush 105 are
fixed and in sliding contact with opposed sides of the commutator
100, which can have a plurality of commutator bars. The armature 96
and commutator 100 are configured to rotate in a counter-clockwise
direction, as described above. The field magnets 92 are configured
to rotate in a clockwise direction, together with the brush dowel
82, also as described above.
[0051] In operation, each armature winding connection is advanced
or indexed increasingly farther ahead of the commutator bars to
ensure that the armature windings remain in sync with the field
magnets 92 as the armature 96 and stator 94 rotate in opposite
directions. As a first commutator bar reaches 180 degrees of
rotation, the armature winding must "step back" or index to its
original position, because when a first commutator bar rotates 180
degrees, the commutator bar contacts a second motor brush 105 on
the opposite side of the commutator 100 from the first motor brush
105. At this point, the field magnets 92 will need to have advanced
ahead incrementally by at least one magnet length to ensure
alignment with the armature winding magnetic field.
[0052] In general, increasing the number of poles allows a larger
gear ratio to be used in the planetary gear train between the
rotor/armature and the brush dowel 82. A larger gear ratio is
desirable to increase the torque of the brush dowel 82 while also
allowing the rotor to spin at higher speeds. In one example, the
planetary gear set 106 can have a -3:1 gear ratio. Other gear
ratios for the planetary gear set 106 are also possible, including,
but not limited to, a -6:1 gear ratio and a -2:1 gear ratio.
[0053] The following FIGS. 9A-9G describe the commutator to
armature lamination connections and show positions of the
rotor/armature 96, commutator 100 and motor brushes 105 at various
rotational positions for a 3:1 gear, 6 magnet combination, numbered
as 92A-92F in the figures. The commutator 100 includes a number of
commutator bars 118 that contact the motor brushes 105. The
armature 96 includes a number of wire slots 120 on the periphery of
the core to permit armature windings to be inserted into the
armature 96.
[0054] As described above for FIG. 6, planetary gear axes 114 and
motor brushes 105 are anchored and fixed in the base housing 68
while the armature 96 rotates counterclockwise and field magnets 92
mounted in the dowel 82 rotate clockwise through a 3:1 planetary
gear set 106. The commutator 100, which includes twenty-four
commutator bars 118 connects to the armature 96, which has eighteen
slots 120, allowing armature lamination poles to run ahead of the
commutator 100, keeping in sync with the rotation of the field
magnets 92. In the figures, the numbered rectangles (1-24)
represent the commutator bars 118 of the commutator 100 and the
numbered circles (1-18) represent slots 120 in the armature 96, to
which wire coils are electrically connected. Table 1 shows the
electrical connection configuration between the respective
commutator bars 118 (numbered 1-24) and slots 120 or wire coils
(numbered 1-18).
TABLE-US-00001 TABLE 1 Electrical Connection Configuration for
Brushroll Wire Coil No./ First Connected Armature Slot Commutator
Second Connected 120 Bar 118 Commutator Bar 118 1 1 22 2 2 23 3 3
24 4 4 -- 5 5 -- 6 6 -- 7 7 -- 8 8 -- 9 9 -- 10 10 13 11 11 14 12
12 15 13 16 -- 14 17 -- 15 18 -- 16 19 -- 17 20 -- 18 21 --
[0055] At 180 degrees rotation as shown in FIG. 9B, polarity of the
brushes 105 switches with line frequency and the armature
lamination connection position indexes 60 degrees backward
(clockwise) to line up with the next field magnet 92. The polarity
is indicated by the waveform icon in FIGS. 9A-9G. This cycle
repeats in sync with the 60 Hz line frequency, rotating the
armature 96 at 3600 rpm, which rotates the brushes 105 at 1200 rpm
in the opposite direction through the planetary gear set 106. The
brush speed can be controlled digitally through pulse-width
modulation (PWM) by artificially switching polarity of rectified DC
current in time with the magnet location and desired speed.
[0056] FIGS. 9C-9F show the second and third rotations of the
brushroll 72. The pattern repeats after three rotations with a -3:1
gear ratio. As shown in FIG. 9G, with a -3:1 gear ratio, at the
start of the fourth rotation, the commutator 100, slots 120, and
magnets 92A-92F have all returned to the original locations shown
in FIG. 9A.
[0057] For other gear ratios, the pattern repeats after different
numbers of rotations. For example, the pattern repeats after six
rotations with a -6:1 gear ratio, two rotations with a -2:1 gear
ratio, and so on for whole number combinations. It is understood
that the number of poles and the winding pattern shown in FIGS.
9A-9G is for the -3:1 gear ratio, and that the number of poles and
the winding pattern would be adjusted accordingly for other gear
ratios. Opposing field magnets 92 have opposite polarity for a
brushroll 72 having two motor brushes 105.
[0058] It is noted that FIGS. 9A-9G show the sequencing pattern,
but the actual motor windings need to be coils. The numbered
circles (1-18) represent the slots 120 in the armature 96. One
exemplary pattern would be to connect in parallel two sets of three
coils connected in series between each of the motor brushes 105.
These patterns would sequence as the armature 96 advances to the
next commutator connections (see FIG. 10-11).
[0059] In an alternate embodiment, shown in FIGS. 12A-12G, the same
winding pattern can be used, but with a 1.5 to 1 planetary gear
ratio. In this case, the polarity of the brushes would not need to
change at 180 degrees rotation.
[0060] In another alternate embodiment, the same winding can be
used with 12 field magnets instead of six. This could be desirable
in a larger application. In this case the polarity of the brushes
would not need to reverse at 180 degrees rotation.
[0061] In addition to vacuum cleaner brushrolls, the embodiment of
the drive described herein can be used to power other devices, such
as power tools or vehicles. This can be either line frequency
driven or electronically timed for speed control.
[0062] To the extent not already described, the different features
and structures of the embodiments may be used in combination with
each other as desired, or may be used separately. That one
brushroll is illustrated herein as having all of these features
does not mean that all of these features must be used in
combination, but rather is done so here for brevity of description.
Furthermore, while the brushroll is shown as being applied to the
base of an upright vacuum cleaner, features of the brushroll may
alternatively be applied to canister-type, stick-type, handheld, or
portable vacuum cleaners. Thus, the various features of the
different embodiments may be mixed and matched in various
configurations as desired to form new embodiments, whether or not
the new embodiments are expressly described.
[0063] While the invention has been specifically described in
connection with certain specific embodiments thereof, it is to be
understood that this is by way of illustration and not of
limitation. Reasonable variation and modification are possible with
the scope of the foregoing disclosure and drawings without
departing from the spirit of the invention which, is defined in the
appended claims. Hence, specific dimensions and other physical
characteristics relating to the embodiments disclosed herein are
not to be considered as limiting, unless the claims expressly state
otherwise.
* * * * *