U.S. patent application number 11/842302 was filed with the patent office on 2008-08-14 for elastic drive belt assembly.
This patent application is currently assigned to ALTO U.S. INC.. Invention is credited to Kelvin E. Bennett.
Application Number | 20080194187 11/842302 |
Document ID | / |
Family ID | 39686245 |
Filed Date | 2008-08-14 |
United States Patent
Application |
20080194187 |
Kind Code |
A1 |
Bennett; Kelvin E. |
August 14, 2008 |
ELASTIC DRIVE BELT ASSEMBLY
Abstract
The elastic drive belt system connects the belt directly to a
drive shaft and driven pulley. The elastic drive belt has a
plurality of longitudinal ribs on the traction side of the belt.
The drive shaft has a plurality of grooves sized and arranged to
receive and engage the longitudinal ribs on the belt to facility
torque transfer and alignment. This system facilitates delivery of
relatively high amounts of torque to the driven pulley using
relatively low horsepower motors. In many applications, such as a
sander, the elastic drive belt system eliminates the need to
readjust the tension on the belt as it wears.
Inventors: |
Bennett; Kelvin E.;
(Decatur, AR) |
Correspondence
Address: |
HUSCH BLACKWELL SANDERS LLP
720 OLIVE STREET, SUITE 2400
ST. LOUIS
MO
63101
US
|
Assignee: |
ALTO U.S. INC.
Springdale
AR
|
Family ID: |
39686245 |
Appl. No.: |
11/842302 |
Filed: |
August 21, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11672817 |
Feb 8, 2007 |
|
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11842302 |
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Current U.S.
Class: |
451/353 |
Current CPC
Class: |
B24B 7/186 20130101;
B24B 55/102 20130101; B24B 23/02 20130101 |
Class at
Publication: |
451/353 |
International
Class: |
B24B 23/02 20060101
B24B023/02 |
Claims
1. A sander for a wooden floor with an elastic drive belt having a
plurality of longitudinal ribs comprising: a drive system, the
drive system consisting of: a drive shaft protruding from an
electric motor, the shaft having a plurality of grooves formed
therein to engage the ribs in the elastic drive belt; a driven
pulley operatively connected to a sanding disk for sanding the
wooden floor, the driven pulley aligned with the grooves in the
drive shaft; the drive shaft and the driven pulley being fixed in
relation to each other; and the elastic drive belt being positioned
around the drive shaft and the driven pulley to transfer torque
from the electric motor to the driven pulley and the sanding disk.
the sander further comprising: a dust fan blade element mounted on
the drive shaft and driven by the electric motor; the dust fan
blade element positioned between the sanding disk and a dust
collection receptacle to facilitate dust control.
2. The apparatus of claim 1 wherein the speed of the drive shaft
and the fan is in the range of about 12,000 rpm to about 14,000 rpm
and the speed of the sanding disk is in the range of about 2,800
rpm to about 3,200 rpm.
3. A sander for a wooden floor with an elastic drive belt having a
plurality of longitudinal ribs comprising: a generally cylindrical
drive shaft protruding from a motor, the drive shaft characterized
by an absence of a pulley on the drive shaft; a driven pulley
remotely located from the drive shaft, each fixed in location to
each other; the elastic drive belt contacting the drive shaft and
the driven pulley to transfer torque from the drive shaft to the
remotely located driven pulley; a dust fan blade element mounted on
the drive shaft; a plurality of grooves formed in the drive shaft
between the fan and the motor, the grooves sized to engage the ribs
in the elastic drive belt; the driven pulley operatively connected
to a sanding disk for sanding wooden floors; and a shroud
surrounding the fan and proximate the sanding disk to direct dust
from the wooden floor, past the fan to a dust receptacle.
4. The apparatus of claim 3 wherein the speed of the drive shaft
and the fan is in the range of about 11,000 rpm to about 13,000 rpm
and the speed of the driven pulley is in the range of about 2,000
rpm to about 4,000 rpm.
5. The apparatus of claim 3 wherein the fan rotates at about 12,000
rpm and the sanding disk rotates about 3,000 rpm.
6. A sander for wooden floors with an elastic drive belt having a
plurality of longitudinal ribs comprising: a generally cylindrical
drive shaft protruding from a motor; a driven pulley remotely
located from the drive shaft; the elastic drive belt wrapping
around and engaging a portion of the drive shaft and also wrapping
around and engaging at least a portion the remotely located driven
pulley to transfer torque from the drive shaft to the driven
pulley, the drive shaft characterized by an absence of a pulley on
the drive shaft; the drive shaft and the driven pulley being fixed
in relation to each other; a plurality of grooves formed in the
drive shaft and sized to engage the ribs in the elastic drive belt;
and the driven pulley operatively connected to a sanding disk for
sanding wooden floors.
7. The apparatus of claim 6 wherein an outside surface of the
driven pulley is substantially smooth.
8. The apparatus of claim 6 wherein an outside surface of the
driven pulley is formed with a plurality of grooves having a size
and shape to engage the longitudinal ribs on the elastic drive
belt.
9. The apparatus of claim 6 further including: a fan mounted on the
drive shaft, and a shroud surrounding the dust fan blade element
and having an inlet proximate the sanding disk and an outlet
connected to a receptacle, the dust fan blade element creating
negative pressure in the inlet to draw a sanding dust through the
duct and deposit the sanding dust in the dust collection bag.
10. The apparatus of claim 9 wherein the speed of the drive shaft
and the fan is in the range of about 12,000 rpm to about 14,000 rpm
and the speed of the driven pulley is in the range of about 2,800
rpm to about 3,200 rpm.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] This application is a continuation application of U.S.
patent application Ser. No. 11/672,817, filed Feb. 8, 2007,
currently pending; the entire disclosure of which is hereby
incorporated by reference.
BACKGROUND OF INVENTION
[0002] The present invention uses an elastic drive belt assembly
containing tensile cord members with elastic properties that does
not require retensioning as the belt wears. This elastic drive belt
assembly can be used in many different applications, such as wooden
floor sanders, floor cleaning machines, metal cutting and grinding
equipment, compressors, pumps, wood working equipment, etc.
[0003] Belt driven sanders for wooden floors have traditionally
been produced for decades with conventional non-elastic drive belts
with tensile cords passing around a drive and driven pulley. Since
the tensile cords are inelastic they permanently elongate as they
wear. This permanent elongation reduces the tension in the belt
which often ultimately causes the belt to slip and not properly
drive the sanding pad. Therefore, conventional belts have to be
retensioned as the belt wears and stretches. Other prior art belt
driven sanders use synchronous "timing" type belts with a drive
pulley and a driven pulley. Pulleys for synchronous drives are more
expensive than conventional pulleys since teeth are machined into
them. Manufacturing variability in the pulleys also increase the
probability (due to additional manufacturing variability) of
machine induced vibration. In addition, to possibly increasing
operator fatigue and component failures, vibration can also cause
"chatter" which appears as undesirable marks on the wooden floor
being sanded.
[0004] Clarke.RTM. American Sanders has been producing sanders for
wooden floors for decades. Some of these sanders are used to sand
the wooden floor where it abuts a wall and are thus called "edgers"
in the trade. One such sander is the Clarke American Super E Edger
described in the Operators Manual and Parts and Service Manual
included in the Information Disclosure Statement. The body of this
Super E Edger is produced separately from the kick-toe extension so
that the tension on the conventional drive belt can be adjusted as
the belt stretches. This is an added expense in the manufacture of
the sander. Specifically, there are elongate channels in the
kick-toe extension that can be adjusted relative to the body with
wing nuts or conventional nuts and bolts. Adjustment of a worn belt
can be time consuming and often requires tools. There is a need to
reduce/eliminate this time consuming adjustment procedure and
reduce the cost of production for this type of sander and other
belt driven products.
[0005] Further, the Clarke Super E sander can produce noise in
excess of about 95 dB(A). Since the noise scale is logarithmic,
slight numeric reductions in the dB(A) value can significantly
reduce the amount of emitted noise in the environment.
[0006] Some vacuum cleaners, like the venerable Kirby.RTM. vacuum
have used elastomeric drive belts wrapped around a drive shaft that
has a slight taper to keep the drive belt in place. These Kirby
drive belts do not have longitudinal ribs, nor does the drive shaft
have grooves. The typical motor in a vacuum cleaner is thought to
have a nominal rating of about 0.5 hp or less and the drive shaft
is thought to have speeds of about 16-20,000 rpm. This results in a
low transfer of torque of about 1.5 to about 3 inch pounds. There
is still a need for a drive belt system that can transfer higher
amounts of torque such as those needed in the sander industry and
other high load applications.
SUMMARY OF THE INVENTION
[0007] The present invention is an elastic drive belt assembly that
includes a) a elastic drive belt possessing longitudinal ribs on
the traction side of the elastic drive belt, b) a drive shaft with
grooves sized and arranged to receive and engage the ribs on the
elastic drive belt and c) a driven pulley. Since the elastic drive
belt assembly does not permanently elongate, the belt does not need
to be re-tensioned as it wears. Conventional non-elastic drive
belts require adjustment as the belt wears and stretches. Costs for
assembly and manufacture of products that utilize this elastic
drive belt assembly should be less than some prior art designs that
use non-elastic drive belts. Products that use this invention
should require less maintenance because the elastic drive belt will
not require readjustment as the belt wears and stretches. One
specific application of this elastic drive belt assembly is a
sander for wooden floors commonly referred to as an edger. In
addition, the edger of the present invention should be quieter than
some prior art edgers.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] FIG. 1 is a perspective view of the sander for wooden floors
viewed from the right front of the apparatus.
[0009] FIG. 2 is a left side elevation view of the sander of FIG. 1
and also illustrates an attached vac hose.
[0010] FIG. 3 is a top view of the sander of FIG. 1
[0011] FIG. 4 is a bottom perspective view of the sander of FIG. 1
with the bottom dust plate in place.
[0012] FIG. 5 is identical to FIG. 4 except the bottom dust plate
has been removed.
[0013] FIG. 6 is a left side section view of the sander, similar to
FIG. 2.
[0014] FIG. 7 is a section view of the sander taken along the line
7-7 of FIG. 6.
[0015] FIG. 8 is a section view of the sander taken along the line
8-8 of FIG. 6.
[0016] FIG. 9 is a section view of the drive assembly including the
drive shaft, drive belt and the driven pulley.
[0017] FIG. 10 is an enlarged section view of the grooves in the
drive shaft and a ion of the elastic drive belt.
[0018] FIG. 11 is a left side elevation view of the sander of FIG.
2, except a dust collection bag has been substituted for the vac
hose.
DETAILED DESCRIPTION OF THE INVENTION
[0019] Referring now to FIGS. 1-3, a sander for wooden floors is
generally identified by the numeral 20 and is often referred to as
an "edger". The sander 20 includes a lower body 22 connected to a
motor housing 90. The lower body 22 is supported by a left caster
assembly 24 and a right caster assembly 26. The motor housing
defines a left handle 28 and a right handle 30. In the right handle
is an on/off switch 32 and in the left handle is an optional motor
speed switch 34. A light assembly 36 is positioned in the upper
part of the body so the light shines down on the floor in front of
the sander.
[0020] The sander is driven by an electric motor 38, better seen in
FIG. 6. An electric cord, 40 provides electricity to the electric
motor and the light assembly. In normal sanding operation, the dust
emitted during the sanding process passes through a vac hose 42 to
a dust collection receptacle, not shown such as an industrial
vacuum cleaner. Operators generally move from the left to the right
while sanding a floor, so it is convenient to have the electric
cord 40 and the vac hose 42 positioned on the left of the sander 20
to allow unencumbered movement to the right. In an alternative
embodiment, better seen in FIG. 11, a removable dust collection bag
is used in lieu of the vac hose and dust collection receptacle. The
dust collection bag may also be referred to as a dust collection
receptacle. A bumper 44 is positioned at the front of the sander to
prevent damage to walls. A sanding disk 46, better seen in
subsequent figures rotates clockwise immediately below the bumper.
Sanding paper 48 is attached to the sanding disk 46 by a bolt 54
and washer 55.
[0021] Referring now to FIGS. 4-8, the internal components of the
sander are shown in various views. The sanding disk 46 is attached
to the sanding disk driver 50 by a plurality of screws 52. The
sanding disk driver 50 threads onto the shaft 104 of the driven
pulley 102. Rotation of the drive shaft 56 imparts rotational
motion via the elastic drive belt 100 to the sanding disk driver
50, the sanding disk 46 and the sanding paper 48 which is in
contact with the wooden floor.
[0022] In FIG. 4 the bottom dust plate 58 is attached to the body
by screws 60. In FIG. 5, the bottom dust plate has been removed to
better show the flow of dust through the sander. An external dust
containment wall 62 surrounds most of the perimeter of the rotating
sanding paper 48. The bottom dust plate 58 and the external dust
containment wall 62 define a dust containment chamber 63. A dust
fan shroud 64 partially surrounds the dust fan blade element 66 and
defines the inlet 68 for the dust fan assembly 70. The dust fan
blade element 66 mounts on the bottom of the motor drive shaft 56
and is secured in place by a retaining key 72 and ring 73.
[0023] The flow of dust through the sander 20 is best seen in FIGS.
5 and 6. Rotation of the dust fan blade element 66 inside the dust
fan shroud 64 creates negative pressure at the inlet 68 of the dust
fan assembly 70. This negative pressure draws the dust from the
dust containment chamber 63 through the inlet 68 as indicated by
the flow arrows in FIG. 6. The dust then exits the dust fan
assembly 70 through the outlet 74, best seen in FIGS. 6 and 8 and
passes through the dust exhaust duct 76, as shown by the flow
arrows, through the vac hose to a dust collection receptacle, not
shown or a dust collection bag, best seen in FIG. 11.
[0024] Referring to FIG. 8, a motor cooling fan assembly 82
includes a cooling fan blade element 84, motor cooling air inlets
86, fan intake baffle 87, a first motor cooling air outlet 88 and a
second motor cooling air outlet 89, better seen in FIGS. 5 and 6.
The motor cooling air inlets 86 are located under the left and
right handles 28 and 30 and are best seen in FIGS. 4 and 5. The
electric motor 38 is positioned in the motor housing 90, as best
seen in FIG. 6. The cooling fan blade element 84 is mounted on the
motor drive shaft 56. Rotation of the motor drive shaft causes the
cooling fan blade element to rotate which creates negative pressure
at the motor cooling air inlets 86. The negative pressure draws
ambient air through the motor cooling air inlets 86 and between the
motor 38 and the motor housing 90 as shown by the flow arrows in
FIG. 6. The ambient air flowing past the motor components provides
convective cooling and draws away heat, thus cooling the motor. The
heated air then exits the body through the first motor cooling air
outlet 88 and a second motor cooling air outlet 89 as shown by the
air flow arrows in FIG. 6. The second motor cooling air outlet 89,
also seen in FIG. 5 directs some of the motor cooling air towards
the floor. Therefore, rotation of the motor drive shaft imparts
rotational motion to both the cooling fan blade element 84 and the
dust fan blade element 66. Rotation of the cooling fan blade
element 84 cools the electric motor 38 and rotation of the dust fan
blade element 66 helps to control unwanted dust caused by the
sander 20.
[0025] Further, applicants believe that the present invention will
reduce the noise level during operation when compared with a prior
art sander like the Clarke Super E Edger. This anticipated noise
reduction should occur due to several reasons. First, the present
invention uses a smaller diameter cooling fan blade element 84 and
smaller diameter dust fan blade element 66 than some prior art
devices. The smaller diameter means that the tip speed is less
which in turn decreases the noise level. In one embodiment, the
diameter of the cooling fan blade element 84 of the present
invention is about 3.75 inches and the diameter of the cooling fan
blade in the Super E Edger is about 4.35 inches. Second, the flow
path of the cooling air is more tortuous in the present invention
than some prior art devices. For every 90 degree change in
direction that the cooling air takes, there is an approximate 3
dB(A) reduction in noise. The motor cooling air inlet 86 of the
present invention is located under the handles of the sander, which
is directed away from the operators ear, unlike some prior art
devices. Furthermore, some of the motor cooling air discharge is
directed towards the floor through second motor cooling air outlet
89, best seen in FIG. 5, and some is directed out the side of the
motor housing 90 through the first motor cooling air outlet 88,
best seen in FIG. 6. The diameter of the dust fan blade element 66
is about 3.75 inches and is less than the 5 inch diameter of the
dust fan blade element in the Super E sander. Reduction in fan
diameter reduces fan tip speed and noise.
[0026] Referring now to FIGS. 6-10, an elastic drive belt 100 wraps
around the motor drive shaft 56 and imparts rotational motion to
the driven pulley 102. The outside circumference 103 of the driven
pulley 102 may be smooth as shown in these drawings to further
reduce production costs. However, if more torque needs to be
transferred, the outside circumference of the driven pulley may
also have grooves sized and arranged to receive and engage the
longitudinal ribs in the elongate belt. The shaft 104 of the driven
pulley 102 extends through one or more bearing assemblies 106 into
the dust containment chamber 63. The driven pulley 102 and the
pulley shaft 104 can be formed from separate components or formed
as one component. Applicants form the driven pulley 102 and the
pulley shaft 104 as one component. The elastic drive belt assembly
generally identified by the numeral 108 as best seen in FIGS. 9 and
10 includes the elastic drive belt 100, the motor drive shaft 56,
and the driven pulley 103. The elastic drive belt assembly 108 may
be positioned outside the dust containment chamber 63, the dust
exhaust duct 76 and the dust flow path to reduce fouling and
contamination by dust and other particles. Likewise, the elastic
drive belt assembly 108 may be positioned outside the motor cooling
air flow path to reduce fouling and other contamination.
[0027] As best seen in FIGS. 9 and 10, the elastic drive belt 100
receives torque direct from the motor drive shaft 56. The Poly
V.RTM. 6 PJ 450 Flexonic, elastic drive belt may be suitable to use
in this invention and is available off-the-shelf from Hutchinson
located at 1835 Technology Drive, Troy, Mich. 48083. This belt from
Hutchinson has six PJ section longitudinal ribs 110 on the traction
side of the belt, an overall nominal length of about 450 mm, and
elastic cords that when installed are stretched (elongated)
approximately 31/2% over its nominal length. The cross section of
the six ribbed belt is about 0.55 inch wide (14 mm) and about 0.157
inch tall.
[0028] The electric motor 38 in this sander has a nominal
horsepower rating of about 1.8 hp. The nominal speed for the motor
drive shaft 56 is in the range of about 12,000 rpm to about 14,000
rpm, having an optimal speed of about 13,500 rpm. The nominal speed
for the sanding disk is in the range of from about 2,800 rpm to
about 3,200 rpm with an optimal working speed of about 3,000 rpm
for a 7 inch sanding disk. In other words, there is a speed
reduction of about 4.63:1. A motor speed of 13,500 rpm allows for
good dust fan performance for a 3.75 inch OD fan.
[0029] The sanding disk 46 is driven by the elastic drive belt 100
that extends from the motor drive shaft 56 to a driven pulley 102.
Speed is reduced by using a driven pulley 102 that is 4.63 times
larger than the OD of the motor drive shaft 56. The nominal
diameter of the motor drive shaft is 1 inch, but it is turned down
to an effective diameter of about 0.787 inches (20 mm) where the
belt is installed. The minimum diameter of a drive shaft that is
suitable for the PJ section belt is about 0.8 inches (20 mm).
However, Hutchinson makes other elastic drive belts with a
plurality of longitudinal ribs that may also be suitable in this or
other applications. For example, the PH cross-section belt from
Hutchison may be able to take torque from a drive shaft having a
diameter as small as 0.25 inches (about 7 mm).
[0030] The motor drive shaft 100 is machined with six grooves 112
that complement the six ribs 110 in the PJ elastic drive belt from
Hutchinson. The grooves 112 contact the sides of each rib 110 and
when coupled with the angle of belt wrap defines the total area of
contact needed to impart the torque required to drive the sanding
pad. Applicant believes that the dimensions for the grooves 112 as
suggested for V-Ribbed Belts, cross sections PJ and PH, in the
Rubber Manufacturers Association draft Standard RMA IP-26 are
suitable for use in this invention. The present invention produces
about 8 inch-pounds of torque using a nominal 1.8 hp electric motor
with a drive shaft speed of about 13,500 rpm. Other cross section
type V-Ribbed elastic belts such as PK, PL, and PM may also be
suitable for use in this invention.
[0031] The OD of the driven pulley is 3.854 inches (97.9 mm) and is
smooth. There are no sidewalls on the pulley. Grooves are not
needed in the driven pulley because there is sufficient contact
area (pulley OD and amount of belt wrap) with the bottom of the six
belt ribs to transfer the torque from the belt to the pulley.
However, grooves may be added to the driven pulley to transfer more
torque.
[0032] The elastic drive belt has a plurality of ribs 110 on the
traction side of the elastic drive belt and a flat surface on the
opposite side of the drive belt. A plurality of grooves 112 are
formed in the motor drive shaft 56 and are sized and arranged to
receive and engage with the ribs 110 on the traction side of the
elastic drive belt. In most prior art applications, a separate
pulley is placed on the motor drive shaft and the drive belt is
driven by this pulley. The present invention eliminates the need
for this drive pulley and therefore is more economical to produce
than some prior art devices. Eliminating the drive pulley also
decreases the probability of machine induced vibration which can
increase component failures, operator fatigue, and the presence of
undesirable marks emitted to the floor being sanded. Furthermore,
the elastic drive belt eliminates the need to readjust the tension
on the belt as it wears, thus saving further on production costs of
the sander and operational maintenance. Productivity increases as
maintenance and service time are decreased.
[0033] FIG. 11 is a side elevation view of the sander 20 similar to
the sander in FIG. 2, except a dust collection bag 114 has been
substituted for the vac hose 42. In FIG. 11, the sander 20 is
running and the dust collection bag 114 is shown in the fully
expanded position since it is pressurized from the exhaust air from
the dust exhaust duct 76. The dust collection bag 114 may sometimes
also be referred to as a dust collection receptacle.
* * * * *