Note: Descriptions are shown in the official language in which they were submitted.
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DRILL-POWERED BRUSH WITH ELECTRICAL SHOCK PROTECTION AND LONG
REACH FUNCTIONALITY
FIELD OF THE INVENTION
The present invention relates generally to rotationally driven brushes,
and more particularly to a drill-powered brush design providing electrical
shock
protection and long reach capabilities useful during cleaning operations, such
as the
removal of spider webs or the like from the exterior of buildings or other
structures.
BACKGROUND
It has been previously proposed to use motor-driven rotation of a brush
to clean up spider webs, whereby the webs are effectively wound onto the
rotating
brush for thorough removal of same from interior or exterior walls or corners
of a
home or other building. On such device featuring a batter operated motor with
a soft
plastic brush can be seen at http://www.niforg.in/upload/pdf
file/motorised_cob.pdf.
A similar device with a spinning head for winding up spider webs can be seen
at
http://www.bugspraycart.com/equipment/tools/web-spinner/.
Other examples of rotating brushes or cleaning devices driven by
dedicated on-board motors or a separate power source such as a conventional
cordless hand drill can be found in U.S. Patent Application Publications
2005/0172437
and 2008/0047085, and U.S. Patents 1,468,219; 2,866,212; 3,293,680; 6,295,681;
6,374,447; 6,553,601; 7,958,587; 7,971,310; 8,024,995; 8,166,665 and
8,256,056.
However, applicant has developed a new design of a drill-powered
rotational brush apparatus suitable that provides improved safety against
electrical
shock while cleaning spider webs near electrical wiring, equipment or
appliances,
while providing a robust durable product with notable long-reach
functionality, for
example useful while cleaning the exterior of a two-storey home or other
building or
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structure of notable size.
SUMMARY OF THE INVENTION
According to one aspect of the invention there is provided a rotational
brush apparatus arranged for driven operation by a hand drill, the apparatus
comprising:
an electrically non-conductive tubular housing having opposing first and
second ends spaced apart in a longitudinal direction and a hollow interior
space
spanning between said first and second ends and bound by a circumferential
wall;
a metal input shaft lying in the longitudinal direction and reaching into
the hollow interior space of the tubular housing from the first end thereof to
place an
internal end of said metal input shaft inside the tubular housing, while
leaving an
external end of the metal input shaft exposed outside the tubular housing
beyond the
first end thereof for engagement in a chuck of the hand drill, the metal input
shaft
shaft being rotatably supported within the tubular housing;
a brush comprising a central core lying parallel to, and in alignment with,
the metal input shaft, with bristles of the brush radiating outwardly from
said central
core at locations outside the tubular housing beyond the second end thereof;
a connection between the metal input shaft and the central core of the
brush to cause rotation of the brush with the metal input shaft under driven
rotation
thereof by the hand drill, the connection being disposed at least partially
within the
interior space of the tubular housing and comprising an electrical insulator
that
electrically isolates the metal input shaft from the brush and from any metal
portion of
the connection that lies externally of the tubular housing beyond the second
end
thereof.
Preferably the electrical insulator resides at an intermediate location
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along the tubular housing that is spaced from the second end thereof.
Preferably the electrical insulator resides nearer to a longitudinal mid-
point of the tubular housing than to the second end thereof.
Preferably the connection comprises a second metal shaft lying parallel
to, and in alignment with, the metal input shaft at a position lying beyond
the internal
end thereof and reaching toward the second end of the tubular housing, the
second
metal shaft being rotatably supported within said tubular housing and being
coupled to
the metal input shaft via the electrical insulator.
Preferably at least a majority of the second metal shaft is contained
within the tubular housing.
Preferably the electrical insulator comprises a sleeve of electrically
insulative material having one end thereof fitted over the internal end of the
metal
input shaft.
Preferably a second end of the sleeve is fitted over a respective end of a
metal component of the connection, preferably the second metal shaft, which is
spaced apart from the input shaft in the longitudinal direction.
Preferably the connection comprises a chuck arranged for selective
detachment and reattachment of the brush thereto.
Preferably the chuck is arranged to enable selective connection thereof
to the external end of the metal input shaft of a matching second rotational
brush
apparatus when the brush is detached from the chuck.
Preferably the external end of the metal input shaft and a connection
end of the brush by which the brush attaches to the chuck have a matching
peripheral
shape.
Preferably the external end of metal input shaft and the connection end
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of the brush have a matching cross-sectional size.
Preferably the chuck comprises metal and is disposed externally of the
tubular housing, and the electrical insulator electrically isolates the chuck
from the
metal input shaft.
Preferably the central core of the brush comprises metal, for example
twisted metal wire.
According to a second aspect of the invention, there is provided a
rotational brush apparatus arranged for driven operation by a hand drill, the
apparatus
comprising:
a tubular housing having opposing first and second ends spaced apart
in a longitudinal direction and a hollow interior space spanning between said
first and
second ends and bound by a circumferential wall;
an input shaft lying in the longitudinal direction and reaching into the
hollow interior space of the tubular housing from the first end thereof to
place an
internal end of said input shaft inside the tubular housing, while leaving an
external
end of the input shaft exposed outside the tubular housing beyond the first
end
thereof for engagement in a chuck of the hand drill, the input shaft being
rotatably
supported within the tubular housing;
a brush comprising a central core and bristles radiating outwardly
therefrom;
chuck connected to the input shaft for rotation therewith at or adjacent
the second end of the tubular housing, the chuck being arranged for selective
attachment and detachment to and from an end of the brush, as well as
selective
attachment and detachment to and from the external end of the input shaft of a
second matching rotational brush apparatus.
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BRIEF DESCRIPTION OF THE DRAWINGS
One embodiment of the invention will now be described in conjunction
with the accompanying drawings in which:
Figure 1 is an exploded side elevational view illustrating use of shaft
5 assemblies from two rotatable brush devices of the present invention to form
an
extended-length rotatable brush driven by a cordless hand drill.
Figure 2 is a cross-sectional view one of the rotatable brush devices of
Figure 1.
In the drawings like characters of reference indicate corresponding parts
in the different figures.
DETAILED DESCRIPTION
Figure 1 illustrates one possible mode of use of the present invention,
wherein components from two rotatable brush devices are assembled together to
collectively form an assembled brush device of increased axial length, useful
for
example in cleaning spider webs or the like from interior ceiling comers, or
exterior
wall corners or overhangs of a building. Each brush device 10 features a shaft
assembly 12 having a generally cylindrical tubular outer housing 14 formed of
a
relatively rigid plastic or other electrically insulative material, a metal
input shaft 16
having an exposed external end 16a situated outside the housing 14 a short
distance
beyond a first end thereof and otherwise residing internally of the housing
14, and a
metal chuck 18 that is disposed externally of the tubular housing 14 at an
opposing
second thereof and is connected to the input shaft 16 in a manner rotatable
therewith.
The exposed external end 16a of the input shaft 16 of either brush assembly is
engagable in either the chuck 18 of the shaft assembly 12 of another brush
device of
the same type, or in the chuck of a hand drill, such as the cordless battery-
powered
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drill 100 schematically shown in Figure 1. Accordingly, the two shaft
assemblies 12 of
Figure 1 can be coupled together in series with one another and with the
cordless drill
100 likewise coupled to one of the shaft assemblies 12, whereby engagement of
a
radially bristled brush 20 into the chuck 18 of the other shaft assembly forms
an
overall brush assembly that is nearly twice the length of one of the brush
devices
would be alone if its individual shaft assembly 12 was coupled directly
between the
drill 100 and the brush 20.
More detail of the particular structure of the shaft assembly 12 of each
brush device 10 is revealed in the cross-sectional view of one of these brush
devices
10 in Figure 2. The tubular housing 14 has a hollow interior spanning the full
axial
length thereof from the first end 14a of the housing 14 to the longitudinally
opposite
second end 14b. A first bushing or bearing 22 is fitted within the first end
14a of the
housing 14, and a second bushing or bearing 24 is likewise fitted within the
housing
14 at the opposing second end 14b thereof. The input shaft 16 has a length
slightly
exceeding half of that of the tubular housing 14, and a substantial majority
of the input
shaft's length resides within the hollow interior space of the housing 14.
Accordingly,
at an approximate halfway point along the axial length the housing 14, the
input shaft
terminates at an internal end 16b. Where it reaches into the housing 14 at the
first
end 14a thereof, the input shaft 16 passes through the first bushing or
bearing 22,
whereby the input shaft 16 is rotatably supported within the housing 14 for
rotation
relative thereto about a central longitudinal axis shared by the housing 14
and the
input shaft 16 lying concentrically therein.
A second metal shaft 26 has a respective external end 26a disposed
outside the tubular housing 14 a short axial distance beyond the second end
14b
thereof, from which the second shaft 26 reaches into the hollow interior space
of the
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tubular housing 14 and toward the internal end 16b of the input shaft 16. Like
the
input shaft, the second shaft 26 has length that slightly exceeds half of that
of the
tubular housing 14, and a substantial majority of the second shaft's length is
received
within the tubular housing 14. The second shaft 26 stops short of reaching the
internal end 16b of the input shaft 16, and thus has an internal end 26b
spaced a
short axial distance from the adjacent internal end 16b of the input shaft at
a location
near the lengthwise center of the tubular housing 14. These adjacent internal
ends of
the two metal shafts 16, 26 are coupled together by a sleeve 28 of plastic or
other
electrically insulative material. This sleeve shaped electrical insulator
28respectively
receives the internal ends 16b, 26b of the two shafts 16, 26 in the two open
ends of
the sleeve 28, whereby the two shafts 16, 26 are secured together for rotation
as one,
and are maintained in the axially separated condition leaving the gap or space
between them inside the sleeve 28. The connection between the sleeve and the
shafts may rely on a friction fit therebetween, use of an adhesive layer
between the
sleeve and each shaft, a combination thereof, or other suitable fastening
means. The
axial space between the two metal shafts may optionally be filled with a
volume of
electrically insulative material to further prevent electrically conductive
contact
between the two shafts, although as described herein further below, other
means for
preventing contact between the internal shaft ends may be additionally or
alternatively
employed.
The gap between the two shafts is sufficient short such that any
flexibility that may be present in the sleeve at this gap is sufficiently low
so to maintain
substantial concentric axial alignment between the two shafts 16, 26, thereby
cooperating with the bushings or bearings 22, 24 to maintain the two shafts in
generally concentric alignment with the surrounding tubular housing 14.
Prototypes of
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the invention have employed commercially available flexible PVC tubing with
nylon
braid reinforcement as the insulating sleeve 28, but it will be appreciated
that other
materials may be employed so long as the tubular housing has sufficient
rigidity to
maintain its generally cylindrical shape closing circumferentially around the
intemal
shafts 16, 26. The outer housing 14 serves as a manual handle by which the
device
is carried and held. The outer housing spans a substantial majority of the
total
collective axial length spanned by the two internal shafts 16, 26 and the
sleeve
shaped insulator coupling 28 therebetween, for example spanning more than 75%
of
this collective internal shaft length, and preferably more than 80% thereof,
for
10 example approximately 90% of the internal shaft length in one embodiment.
Accordingly, the brush device 10 can be gripped with two hands at any number
of
locations spread out over a wide range of the overall length of the device 10.
The radial space maintained by the bushings or bearings 22, 24
between the inner surface of the tubular housing's circumferential wall and
the internal
shafts 16, 26 housed therein exceeds the wall thickness of the sleeve 28,
whereby
sufficient clearance is maintained between the housing the sleeve 28 to ensure
unencumbered rotation of the internal shafts 16, 26 and sleeve 28 inside the
housing
14.
The portion of the second shaft 26 that extends outside the tubular
housing 14 reaches into an axial through-bore 30 of the chuck 18 at the second
end
14b of the housing 14. Within this bore 30, the chuck 18 and second shaft 26
are
fixed together for rotation as a single unit, whereby rotation of the external
end 16a of
the input shaft 16 will drive matching rotation of the chuck 18 at the
opposing end of
the housing 14. As shown, the chuck 18 may be counter-bored to a larger
internal
diameter at the proximal end 18a thereof that faces toward the housing 14 so
that the
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second end of the housing 14b fits a short axial distance into this counter-
bored end
of the chuck 18. Sufficient clearance is provided between the exterior surface
of the
housing 14 and the interior surface of the counter-bored end of the chuck 18
to allow
unencumbered rotation of the chuck 18 relative to the housing 14. As shown,
the
second end 14b of the housing 14 may feature an area of reduced outer diameter
relative to the remainder of the housing 14 to contribute to this rotational
clearance
between the chuck 18 and the housing 14.
Near a distal end 18b of the chuck that is located opposite to the
housing 14, a threaded radial bore 32 passes through the circumferential wall
of the
chuck 18 from the exterior thereof into the central axial bore 30 of the
chuck. The
external end 26a of the second axial shaft 26 stops short of reaching the
radial bore
32. The brush 20 is of a known commercially available type featuring a twisted-
wire
central core 34 from which radial bristles 36 emanate outward around the full
circumference of the core over the majority of the core's axial length. At an
unbristled
end of the wire core 34, a cylindrical metal sleeve 38 is fitted onto the wire
core 34
and fixed thereto, for example adhesively or by other means, thus forming an
end
fitting that is slidable into axial bore 30 of the chuck 18 in a close fitting
but manually
removable manner. The outer diameter of this sleeve-shaped end fitting 38 is
of
equal to the outer diameter of the internal shafts 16, 26, which may be hollow
or solid.
Accordingly, the sleeve and shafts have a matching peripheral shape (e.g.
cylindrical
in the illustrate embodiment) and matching cross-sectional size (e.g. outer
diameter of
the cylinder).
A set screw 40 is engaged in the threaded radial bore 32 and advanced
therein in order to tighten against the sleeve fitting 38 at the connection
end of the
brush 20 and clamp same against the opposing side of the chuck's internal bore
30,
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thus securing the end fitting 38 to the chuck 18 in a rotationally fixed
position relative
thereto, such that the brush will be rotationally driven about the
longitudinal axis of its
wire core 34 under rotation of the input shaft 16 at the opposite end of the
housing 14.
Turning back to the first end 14a of the housing 14, an end cap 42 may
5 be externally fitted over this end of the housing. The end cap 42
features a central
aperture therein that lies in alignment with the central longitudinal axis of
the housing
to accommodate passage of the input shaft 16 through the cap 42 in order to
place
the external end 16a of the input shaft in its exposed position outside the
housing for
engagement by the drill chuck of the cordless drill 100. As the diameter of
the input
10 shaft 16 is equal to the outer diameter of the sleeve fitting 38 on the
brush 20, the
external end 16a of the input shaft can altematively be received in the chuck
18 of
another brush device 10 instead of the drill chuck, as demonstrated by Figure
1,
whereby two or more identical shaft assemblies can be assembled end-to-end in
series with one another in axially aligned positions to assemble a longer
overall brush
unit in which the cordless drill 100 engaged to the input shaft at one end of
the series
is rotatably coupled to the brush 20 installed at the other end of the series.
A stop collar or cross-pin 44 is fixed or releasably locked to the input
shaft 16 just outside the cap 42 of the housing 14 at a distance axially
spaced from
the external end 16a of the input shaft in order to limit sliding of the input
shaft 16
further into the housing 14. At the other end 14b of the housing 14, a similar
stop
function is provided by an internal shoulder 46 of the chuck 18 that is
defined at the
transition between the brush-receiving bore 30 at the distal end 18b of the
chuck and
the larger counter-bore at the proximal end 18a of the chuck. This shoulder 46
abuts
against the respective end 14b of the housing 14, thereby preventing the
attached
second shaft 26 from sliding further into the housing 14. Accordingly, the
illustrated
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embodiment maintains empty space between the internal ends 16b, 26b of the two
internal shafts 16, 26, as sliding together of the two shafts into contact
with one
another is prevented by these stop features at the opposing ends of the
housing to
prevent short circuiting of the electrical isolation provided between the
shafts by the
insulator sleeve 28.
Whether a single brush device 10 or multiple brush devices are used to
form the connection between the drill and the brush, electrical isolation
between the
brush and the hand-carried drill 100 is provided by the sleeve-shaped
insulator 28,
thereby gaining advantage of the strength and shape-retaining rigidity
provided by the
use of metal shafts (whether solid shaft, or hollow shafts of reduced weight),
and
reliability of a metal chuck 18 without exposing the user to risk of
electrocution if the
wire-core of the brush 20 or the metal chuck 18 should inadvertently come into
contact with an electrical wire or other electrical source during use of the
brush device
10.
It will be appreciated that similar electrical isolation between the brush
and input shaft could be provided in the connection between the brush and
input shaft
at locations other than at an insulator sleeve coupling the metal input shaft
to a
second internal metal shaft. For example, it could be possible to employ
insulating
material around and over the shaft end 26a at the second end 14b of the
housing to
isolate this shaft end from the metal chuck 18 and the connection end of the
brush 20
dngaged therein. In such an embodiment, the use of two separate shafts 16, 26
may
not be necessary, with a single internal shaft thus extending from the first
external end
16a to the second external end 26a.
Since various modifications can be made in my invention as herein
above described, and many apparently widely different embodiments of same made
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within the scope of the claims without departure from such scope, it is
intended that all
matter contained in the accompanying specification shall be interpreted as
illustrative
only and not in a limiting sense.
