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.

Description

CROSS-REFERENCE TO RELATED APPLICATION(S)

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

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.

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.

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.

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.

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.

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

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

In the drawings:

FIG. 1 is a cross-sectional view of a prior art DC motor assembly;

FIG. 2 is a schematic view of a vacuum cleaner;

FIG. 3 is a perspective view of a vacuum cleaner base;

FIG. 4 is an exploded view of the vacuum cleaner base of FIG. 2;

FIG. 5 is a partially exploded view of a brushroll of the vacuum cleaner base of FIG. 2;

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;

FIG. 7 is a cross-sectional view of the brushroll through line VII-VII of FIG. 4;

FIG. 8 is a cross-sectional view of the brushroll through line VII-VII of FIG. 4;

FIG. 9A-9G are schematic views of a first embodiment of an armature winding diagram for a brushroll ;

FIG. 10 is a schematic view of a second embodiment of an armature winding diagram for a brushroll;

FIG. 11 is a diagram of a winding pattern for the armature winding diagram of FIG. 10; and

FIG. 12A-12G are schematic views of a third embodiment of an armature winding diagram for a brushroll.

DESCRIPTION OF EMBODIMENTS OF THE INVENTION

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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 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	—

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.

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.

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.

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).

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.

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.

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.

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.

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.

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.