U.S. patent application number 11/103018 was filed with the patent office on 2006-10-12 for hand held electric polisher.
Invention is credited to Charles D. Syverson.
Application Number | 20060228994 11/103018 |
Document ID | / |
Family ID | 37037196 |
Filed Date | 2006-10-12 |
United States Patent
Application |
20060228994 |
Kind Code |
A1 |
Syverson; Charles D. |
October 12, 2006 |
HAND HELD ELECTRIC POLISHER
Abstract
A polisher has a polishing disc on a shaft driven by a brushless
DC motor driven by a motor controller mounted spaced from the
polisher and adjacent a ground fault interrupt circuit and a power
plug. Power and control wires form a cord that provides
communication between a speed control switch, and a speed set
switch, mounted on a handle of a polisher housing, which is a
magnetic field sensor responsive to a movable magnet. The speed set
switch sends a signal to the motor controller either to maintain
the current speed of the motor or to allow the speed of the motor
to vary in accordance with the output of of the speed control
switch. The speed control switch is a variable output switch which
can be an optical potentiometer constructed by reflecting light
from a light source off a reflective surface forming part of a
spring loaded trigger.
Inventors: |
Syverson; Charles D.; (North
Mankato, MN) |
Correspondence
Address: |
STIENNON & STIENNON
612 W. MAIN ST., SUITE 201
P.O. BOX 1667
MADISON
WI
53701-1667
US
|
Family ID: |
37037196 |
Appl. No.: |
11/103018 |
Filed: |
April 11, 2005 |
Current U.S.
Class: |
451/6 |
Current CPC
Class: |
B24B 29/02 20130101;
B24B 23/02 20130101; H01H 9/06 20130101; B24B 47/12 20130101; H01H
36/00 20130101 |
Class at
Publication: |
451/006 |
International
Class: |
B24B 49/00 20060101
B24B049/00 |
Claims
1. A handheld polishing tool comprising: a housing having at least
one handle extending therefrom; a polishing shaft mounted for
rotation on the housing; a brushless DC motor mounted within the
housing; a gear train connecting the motor to the polishing shaft
whereby the polishing shaft is driven to rotate by the motor, a
power cord, for suppling power to the motor, extending from the
housing a selected distance to a power plug; a motor speed control
circuit mounted spaced from the housing along the power cord, the
motor speed control circuit supplying power to the motor, and in
speed controlling relation to the motor; and a switch having a
variable output, the switch mounted to the handle and connected by
a communications link to the motor speed control circuit and
arranged to cause the motor speed control circuit to vary the speed
of the motor in proportion to the variable output of the
switch.
2. The handheld polishing tool of claim 1 wherein the motor speed
control circuit is located at the power plug.
3. The handheld polishing tool of claim 1 further comprising a
ground fault interrupt circuit located at the power plug.
4. The handheld polishing tool of claim 3 wherein the ground fault
interrupt circuit and motor speed control circuit are incorporated
into a single housing at the power plug.
5. The handheld polishing tool of claim 1 further comprising: a
spray nozzle mounted to the housing; and a supply hose connected to
the spray nozzle, wherein the supply hose is connected to a source
of pressurized water.
6. The handheld polishing tool of claim 1 farther comprising a
binary switch mounted to the handle and connected by a second
communication link to the speed control circuit, the switch
arranged to cause the motor speed control circuit to maintain the
motor speed at a selected speed, or to cause the motor speed
control circuit to respond to the variable output switch.
7. The handheld polishing tool of claim 6 wherein the binary switch
comprises a magnet movable with respect to a magnetic field
sensor.
8. The handheld polishing tool of claim 7 wherein the magnet
movable with respect to the magnetic field sensor is mounted to a
shaft which extends through the handle extending from the housing,
and is slidably mounted with respect to the housing so that the
magnet is contained within the handle and is movable with respect
to the magnetic field sensor, the magnetic field sensor being fixed
with respect to the handle.
9. The handheld polishing tool of claim 8 wherein a first magnet
and a second magnet are mounted within the handle and are fixed to
the handle, and the movable magnet is arranged to move between said
first magnet and said second magnet past the magnetic field sensor,
and wherein the first magnet, the second magnet and the movable
magnet have magnetic poles arranged so that the movable magnet is
held against said first magnet or said second magnet when engaged
with said first magnet or said second magnet by magnetic
attraction.
10. The handheld polishing tool of claim 1 wherein the switch has a
variable output and has an optical sensor and a reflecting surface
movable with respect to the optical sensor so that the optical
sensor projects light towards the reflecting surface and receives
light from the reflecting surface, the received light from the
reflecting surface controlling the output of the optical sensor and
thus of the switch.
11. The handheld polishing tool of claim 1 wherein the motor is
varied between about 12,500 rpm to about 27,500 rpm, and wherein
the gear train connecting the motor to the polishing shaft has a
ratio to produce in the polishing shaft a corresponding speed of
between about 2,500 rpm and about 5,500 rpm.
12. A handheld polishing tool comprising: a housing; a polishing
shaft mounted for rotation on the housing; a motor mounted within
the housing; a gear train connecting the motor to the polishing
shaft whereby the polishing shaft is driven to rotate by the motor;
a power cord extending from the housing a selected distance to a
power plug; a motor speed control circuit mounted spaced from the
housing along the power cord, the motor speed control circuit
supplying power to the motor, and in speed controlling relation to
the motor; and a switch having a variable output, the switch being
mounted to the housing and connected by a communication link to the
motor speed control circuit and arranged to cause the motor speed
control circuit to vary the speed of the motor in proportion to the
variable output of the switch.
13. The handheld polishing tool of claim 12 wherein portions of the
housing defining a handle; and wherein the switch having a variable
output is mounted to the handle; further comprising: a binary
switch mounted to the handle and connected by a second
communication link to the speed control circuit, the binary switch
being arranged to cause the motor speed control circuit to maintain
the motor speed at a selected speed, or to cause the motor speed
control circuit to respond to the variable output switch.
14. The handheld polishing tool of claim 13 wherein the binary
switch comprises a magnet movable with respect to a magnetic field
sensor.
15. The handheld polishing tool of claim 12 wherein the variable
output switch has an optical sensor and a reflecting surface
movable with respect to the optical sensor so that the optical
sensor projects light towards the reflecting surface and receives
light from the reflecting surface, the received light from the
reflecting surface controlling the output of the optical sensor and
thus of the switch.
16. A handheld polishing tool comprising: a housing; a polishing
shaft mounted for rotation on the housing; a motor mounted within
the housing; a gear train connecting the motor to the polishing
shaft whereby the polishing shaft is driven to rotate by the motor;
a spray nozzle mounted to the housing; a supply hose connected to
the spray nozzle, wherein the supply hose is connected to a source
of pressurized water; a power cord extending from the housing a
selected distance to a power plug; a motor speed control circuit
mounted to the power plug, the motor speed control circuit
supplying power to the motor, and in speed controlling relation to
the motor; and a switch having a variable output, the switch
mounted to the housing and connected by a communication link to the
motor speed control circuit and arranged to cause the motor speed
control circuit to vary the speed of the motor in proportion to the
variable output of the switch.
17. The handheld polishing tool of claim 16 wherein portions of the
housing defining a handle; and wherein the switch having a variable
output is mounted to the handle; further comprising: a binary
switch mounted to the handle and connected by a second
communication link to the speed control circuit, the binary switch
being arranged to cause the motor speed control circuit to maintain
the motor speed at a selected speed, or to cause the motor speed
control circuit to respond to the variable output switch.
18. The handheld polishing tool of claim 16 wherein the switch
having a variable output has an optical sensor and a reflecting
surface movable with respect to the optical sensor so that the
optical sensor projects light towards the reflecting surface and
receives light from the reflecting surface, the received light from
the reflecting surface controlling the output of the optical sensor
and thus of the switch.
19. The handheld polishing tool of claim 16 further comprising a
ground fault interrupt circuit located at the power plug.
20. The handheld polishing tool of claim 19 wherein the ground
fault interrupt circuit and motor speed control circuit are
incorporated into a single housing at the power plug.
Description
CROSS REFERENCES TO RELATED APPLICATIONS
[0001] Not applicable.
STATEMENT AS TO RIGHTS TO INVENTIONS MADE UNDER FEDERALLY SPONSORED
RESEARCH AND DEVELOPMENT
[0002] Not applicable.
BACKGROUND OF THE INVENTION
[0003] The invention relates to handheld polishing tools in
general, and particularly to tools suitable for polishing glass and
plastic.
[0004] Glass and plastic windows are essential for all vehicles
which are driven or occupied by humans where it is desirable to
both be protected within the vehicle and yet be able to observe the
environment surrounding the vehicle. Whether visibility is
necessary for navigation, safety, reconnaissance, or enjoyment, it
is important that the windows formed of glass and plastic be as
free of scratches as possible so as not to obscure the vision
through the window. However, by their very nature, vehicles such as
planes, automobiles, trains, or boats move through the air, and are
thus often abraded by particles entrained in the air. Furthermore,
windshield wipers can entrap abrasive particles which are then
rubbed against the surface of the window, producing scratches. In
addition, the chemical activity of rain, cleaning fluids, sea
water, or other fluids can chemically etch glass or plastic thereby
reducing its transparency. Replacing vehicle windows which have
impaired transparency is often not cost-effective.
[0005] To extend the life of vehicle windows, techniques have been
developed to remove surface imperfections such as scratches,
crazing, and chemical etching, by polishing the window surface to
remove the optical imperfections, and creating a smooth polished
surface. Variable speed drills and polishers exist which can be
used with flexible polishing disks which may have polishing
surfaces, or which may use polishing compounds which are placed
between the polishing disks and the window surface. The polishing
process can require a number of steps depending on the depth of the
optical imperfections to be removed. It can also be important to
control the speed of the polishing disk to control the polishing
action, and at the same time to avoid overheating of the window
surface. Overheating may result in the formation of particles
clumping which can result in scratches, or overheating may cause
damage to the window material itself. What is needed is a durable
polisher which can operate at high speeds, which can maintain set
speeds, and which is lightweight and easy to control.
SUMMARY OF THE INVENTION
[0006] The handheld electric polisher of this invention has a
housing, and a polishing shaft supported on bearings on the
housing. The housing has a handle extending at approximately right
angles to a polishing shaft and integrally formed with the housing.
The polisher is driven by a brushless DC motor which has a rotor of
permanent magnets mounted to a motor shaft. The motor shaft is
mounted to the housing by bearings. The motor shaft terminates in a
helical gear which forms a helical pinion gear with a helical wheel
gear mounted to the polishing shaft. The gearing ratio between the
pinion and the wheel is approximately five, so that when the motor
speed is varied between 12,500 rpm to 27,500 rpm, the speed of the
polishing shaft varies between about 2,500 and 5,500 rpm.
[0007] The brushless DC motor has a steel laminated core with three
or six windings which are driven by a motor controller which is
mounted with a ground fault interrupt circuit at a power plug. The
motor controller supplies power through three wires extending
between the controller and a polisher housing so that the motor
controller is spaced from the polisher housing. Four control wires
run along the three power wires, to form a seven wire cable that
provides a communications link to a speed control switch, and to a
speed set switch mounted on the handle. The speed control switch is
the variable output switch. The output of the variable switch is
used to control the speed of the motor through the controller. The
speed set switch sends a signal to the motor controller either to
maintain the current speed of the motor or to allow the speed of
the motor to vary in accordance with the output of of the speed
control switch. The speed set switch is a magnetic field sensor
which is mounted in the handle of the housing and actuated by a
movable magnet. The speed control switch is an optical
potentiometer constructed by reflecting light from a light source
off a reflective surface mounted to a spring loaded trigger.
[0008] It is a feature of the present invention to provide an
electric handheld polisher with increased durability.
[0009] It is another feature of the present invention to provide an
electric handheld polisher of lighter weight.
[0010] It is a further feature of the present invention to provide
an electric handheld polisher on which a water spray is
mounted.
[0011] It is yet another feature of the present invention to
provide an electric handheld polisher which separates the motor
controller from the motor housing.
[0012] Further objects, features and advantages of the invention
will be apparent from the following detailed description when taken
in conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] FIG. 1 is an illustrative view of the polisher of this
invention, with one half of the housing removed.
[0014] FIG. 2 is enlarged fragmentary view of the speed control
trigger and sensor of the polisher of FIG. 1.
[0015] FIG. 3 is an enlarged fragmentary view of a speed set switch
and magnetic sensor of the polisher of FIG. 1
[0016] FIG. 4 is a schematic view of the polisher of FIG. 1
including a plug-mounted speed controller and a water supply.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0017] Referring more particularly to FIGS. 1-4 wherein like
numbers refer to similar parts, a handheld polisher 20 is shown in
FIG. 1. The polisher 20 has a housing 22 comprised of a right hand
portion 24 shown in FIG. 1 and a left-hand portion 25 shown in FIG.
4. A polishing disk 26 constructed of rubber or other flexible
material is mounted for rotation on a shaft 28. The shaft 28 is
supported on the housing 22 by a first bearing 30 and a second
bearing 32 and has a forty-one tooth helical wheel gear 34 which is
keyed to the shaft 28 between the first bearing 30 and the second
bearing 32. The first bearing 30 is larger than the second bearing,
and receives the majority of the thrust load from the polishing
disk 26. The shaft 28 decreases in diameter as it enters the first
bearing 30, and to a lesser extent as it enters the second bearing
32 so that thrust loads are applied principally to the first
bearing but also to the second bearing.
[0018] The shaft 28 to which the polishing disk 26 is mounted is
driven by a three phase brushless DC motor 36. The motor 36 has a
four pole permanent magnet rotor 38 mounted to a motor shaft 41
which terminates in a seven tooth helical pinion gear 40 which
drives the forty-one tooth helical gear 34. The gears 40, 34 in
FIG. 1 are illustrated with straight teeth for simplicity. The
motor shaft 41 is mounted to the housing 22 between a third
bearings 42 and a fourth bearing 44. A radial fan 46 as well as the
rotor 38 are mounted between the bearings 42, 44. The fan 46 fits
within a fan housing 48 formed by portions of the housing 22 and
draws air from portions 50 of the housing 22 which contain the
motor 36. Air vent holes 54, shown in FIG. 4, allow air to be drawn
into the housing past the motor 36, and to then be vented through
openings 56 in the fan housing 48. A motor stator 52 is mounted to
the housing 22. The stator 52 surrounds the rotor 38 and is mounted
within the motor containing portions 50 of the housing 22.
[0019] The rotor 38 is driven by three or six electrical windings
58 which are wound within six slots 60 formed by a plurality of
ferrous laminations which form the stator 52. The windings 58 are
Y-connected with one or two coils from each phase on each arm or
leg of the Y. If two coils are used with one half the number of
turns for each single phase, the coils can be wound around opposite
core posts defined by the six slots. Each leg or arm of the Y is
fed with one of three phases of the power through three wires of
the cord 62. The windings are suppled with full-wave rectified 120
VAC or approximately 160 VDC. A speed controller 64 is mounted a
selected distance away from the polisher 20. As shown in FIG. 4,
the speed controller 64 is preferably mounted at a plug 66 which
terminates the power and controller cord 62. Advantageously, a
ground fault interrupt circuit 67 will be incorporated into the
same housing 71 as the speed controller 64. The controller 64 is a
conventional motor controller which controls motor speed utilizing
back EMF so that a Hall effect sensor or the like are not required
on the motor stator 52. The power and controller cord 62 has three
power wires and four control wires. A handle 69 extends from the
housing, and is preferably formed integrally with the housing. The
control wires receive input from a linear output optical sensor 68,
mounted in the handle 69 and controlled by a trigger 70 which is
biased by a spring 72. The control wires also receive a speed set
signal from a binary magnetic sensor 74 which is used to command
the speed controller to hold the current speed, as set by the
position of the trigger 70 and the output of the optical sensor
68.
[0020] The speed control trigger 70 is biased to a first position
by the spring 72 and can be depressed to a second position by
compression of the spring as shown in FIG. 2.
[0021] The optical sensor 68 is mounted to a circuit board 76 and
comprises a light emitting diode 78, and a photo sensor 80 arranged
to receive the light reflected from a surface 82 of the trigger 70.
Depressing the trigger 70 against the spring 72 moves the surface
82 closer or further from the optical sensor 68. Movement of the
trigger 70 changes the spacing between the light reflecting surface
82 and sensor by approximately 1:2 which in turn controls the speed
of the motor 36. The intensity of of the light received by the
photo sensor 80 as reflected from the surface 82 increases as the
surface 82 moves closer to the optical sensor 68. The output of the
optical sensor 68 can be designed to approximate a linear response
to the movement of the trigger 70, or an algorithm may be used to
linearize the output of the photo sensor 80. The output of the
optical sensor 68 is sent to the speed controller 64 and used to
set the speed of the motor 36 in accordance with the movement of
the trigger 70.
[0022] When it is desired to hold the speed of the motor 36 at a
selected speed determined by movement of the trigger 70, a
transverse switch 84 consisting of a short shaft 86 mounted
transverse to the handle 69 is used. As shown in FIG. 3, a
permanent magnet 88 is mounted fixed to the short shaft 86 and
positioned within the housing 22. A binary type Hall effect sensor
74 is caused to change state as the permanent magnet 88 passes by
the sensor 74. Permanent washer shaped magnets 90, 92 are mounted
to the housing 22 to hold the permanent magnet 88 in one of the two
states illustrated in FIG. 3. Switching between illustrated states
causes a change in state of the Hall effect sensor 74 which is
communicated to the speed controller 64, and used by the speed
controller to control locking or releasing a set speed.
[0023] The handheld polisher 20, as shown in FIG. 4, has a water
spray nozzle 93 mounted to a spray housing 91 which contains a
valve 94 of the push button type valve will be installed into the
mounting bracket such that a button 95 protrudes out the top of the
bracket and the operator only needs to push down on the button to
operate the water misting action which controls a flow of water
from a pressurized water supply 96 to the spray nozzle 93 by way of
a supply hose 98. A optional lever 97 as shown, can be used to
depress the button 95. The water supply hose 98 may be supported on
the housing 22 by a clip 99. The spray housing 91 may be mounted to
the polisher housing 22 in a position so that the spray nozzle 93
can spray water 100 on to a window 102 to facilitate cooling and
lubricate the polishing process on the window 102. The spray nozzle
93 if construed of LOC-LINE.RTM. components can be readily adjusted
to point the water spray in a desired direction.
[0024] Depending on the type of surface being polished and the
particular polishing compound and/or polishing disks used, the
desire to speed the polishing may vary. Through operator experience
or by consulting a readout of the motor speed, the trigger is used
to select and to vary the speed of the motor and thus the polishing
disk 26. The gearing ratio between gears 34 and 40 functions as a
reduction gear having a speed ratio of about 5:1 so that when the
motor speed is varied between about 12,500 to about 27,500 rpm, the
speed of the polishing shaft 28 varies between about 2,500 rpm and
about 5,500 rpm. The actual maximum surface speed at which
polishing takes place is dependent on the diameter of the polishing
disk 26.
[0025] It is understood that the invention is not limited to the
particular construction and arrangement of parts herein illustrated
and described, but embraces all such modified forms thereof as come
within the scope of the following claims.
* * * * *