Note: Descriptions are shown in the official language in which they were submitted.
CA 02589985 2007-06-07
WO 2006/062522 PCT/US2004/041257
HIGH TORQUE DUAL CHAMBER TURBINE ROTOR FOR HAND HELD OR
SPINDLE MOUNTED PNEUMATIC TOOL
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a pneumatically powered, hand held or spindle-
mounted
lightweight tool suitable for grinding and polishing and, more particularly,
to a turbine
rotor for a lightweight, grinding tool driven by an air-powered reaction
turbine. The
turbine rotor creates high torque for a drive shaft without a significant
increase in size or
weight of the grinding tool.
2. Description of Related Art
In the prior art, light-weight pneumatic tools have been used for a variety of
functions, such as grinding, polishing, metal or plastic finishing, engraving,
drilling, and
deburring. The tool variations include hand-held and machine spindle-mounted
embodiments. Hand-held. tools often include a narrow cylindrical exterior
housing that
includes a handle portion enclosing the rotor and a drive shaft that is held
much like a
pencil or pen. Lightweight pneumatic grinding tools can be hand held for
longer periods
of time than a comparable electric motor tool which is much heavier without
harm to the
user.
Prior art pneumatically-powered tools utilize either a vane-type fluid motor
or a
reactive rotor. The present invention does not employ a vane-type motor but
utilizes a
reactive rotor. The reactive rotor expels high pressure, high velocity air
tangentially
from the rotor peripherally to obtain torque. The rotor is coupled to the
primary drive
shaft therein.
U.S. Patent No. 5,566,770 which has a common assignee with the present
invention, provides an angled spindle that is relatively lightweight driven by
a single
chamber rotor. U.S. Patent No. 4,776,752, which also has a common assignee
with the
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present invention, teaches a single chamber turbine rotor that is relatively
lightweight
and includes a high-speed governor.
Although the torque provided in current turbine rotors is adequate for
grinding
and polishing tools that are lightweight and compact, higher torque in some
applications
of grinding and polishing is desirable. However, enlarging the tool rotor (and
therefore
the housing) to increase torque could greatly increase the weight, size and
volume of the
tool housing and therefore reduce the hand-held, lightweight advantages of the
tool.
The present invention increases the torque of a rotor driven pneumatic tool
significantly without concomitant increases in weight, size or complexity of
operation or
manufacture of the tool. In fact, an increase in torque becomes possible with
a decrease
in diameter of the tool. For example, where a rotor approximately one inch in
diameter
would provide approximately 0.2 horsepower at 50,000 revolutions per minute
("RPMs"), with the present invention a rotor of only 3/4 inch in diameter
provides
approximately 0.3 horsepower at 50,000 RPMs. In addition to an increase in
power, the
present invention provides for a slimmer tool profile. Moreover, the present
invention
also reduces the pressure that is necessary to idle the rotor in comparison to
a single rotor
of comparable size and material from three cubic feet per minute for the one
inch single
rotor to two cubic feet per minute for a 3/4 inch dual rotor.
The present invention uses a rotor comprising a single, compact body having
dual, high pressure air receiving chambers that share a common wall, to reduce
size and
weight for increased torque. Both rotor body chambers have tangential exhaust
nozzles
that generate torque to rotate the rotor. The present invention may also
include dual
automatic speed governors without additional complexity.
A lightweight tool is also desirable in a spindle mount since the tool is
supported
on a moveable arm.
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BRIEF SUMMARY OF THE INVENTION
A high-torque turbine rotor mounted in a hand-held or spindle mounted
pneumatic tool narrow housing on a drive shaft. The rotor body has a threaded
central
aperture that receives and is fixedly attached to the threaded drive shaft.
The rigid drive
shaft is partially hollow and has two pairs of openings that serve as inlets
to the rotor
body for high-pressure air that provides the motive force on the rotor body
for turning
the drive shaft. A grinder member for grinding is affixed to one end of the
drive shaft.
The opposite end is attached to a flexible air hose or high-pressure air
supply.
The cylindrical rotor body has a rigid cylindrical outer wall and an inner
central
wall dividing the rotor body into two separate compartments, with an open
front and an
open back. The cylindrical rotor body has a first annular chamber, a second
annular
chamber, and a common inner wall. A front wall and a back wall are connected
to the
rotor cylindrical wall forming two separate air receiving chambers.
The front, back and inner rotor walls each have a threaded aperture for
attachment to the threaded drive shaft. The rotor cylindrical body and the
front, inner
and back walls provide two separate chambers in the rotor, a first annular
chamber and a
second annular chamber. The rotor cylindrical wall has a plurality of
tangentially
directed passages strategically spaced to direct high pressure internal air
outwardly,
resulting in torque on the rotor and thus, the shaft.
In the preferred embodiment, each rotor chamber in the rotor body receives
high
pressure air from the drive shaft inlets. Each rotor body chamber has a
cylindrical
interior shape and includes four separate tangential air passages that exhaust
high-
pressure air tangentially and peripherally, causing a reactive force as the
air is expelled
from both chambers. The inside peripheral wall of each chamber has four
tapered
portions proceeding from a narrow portion to a thicker portion, the thicker
portion
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accommodating the four tangential exhaust air passages. The housing tangential
air
exhaust passages are spaced approximately 90 degrees apart around the annular
chamber.
In the preferred embodiment, there are two separate chambers separated by the
common
inner wall, each of which has four separate exhaust passages that are
peripheral and
tangential. Thus, for each rotor body there are eight separate exhaust
passages. The use
of eight separate passages greatly increases torque for a single rotor.
In the preferred embodiment each rotor body chamber (the first chamber and
second chamber) includes a governor to limit the overall RPM of the rotor and
therefore
the shaft as described in U.S. Patent No. 4,776,752. The governor and each
chamber
described in the '752 patent includes an annular perforated barrier and a
resilient o-ring
that fits on the inside of the annular perforated barrier. The rotor chamber
walls include
annular grooves for retaining the annular perforated barrier. As the RPMs of
the rotor
increase, the resilient o-ring expands under centrifugal force outwardly,
resiliently
engaging the annular perforated barrier, thereby shutting off air under
pressure from the
air inlet to the peripheral exhaust nozzles to regulate the amount force and
therefore the
RPMs of the rotor.
There are various types of turbine rotors available. However, to increase the
amount of torque obtained in a current rotor, the turbine rotor housing would
have to, be
enlarged, causing a larger housing, increased weight and possible vibration,
chatter and
increased wear on the turbine parts and operator fatigue.
It is an object of the present invention to provide a lightweight pneumatic
grinding tool that is able to maintain a constant rotational speed when
subjected to a load
without producing unwanted vibration, which also provides increased torque
while
retaining a narrow tool housing for comfortable holding during use.
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It is also an object of the present invention to provide a lightweight
grinding tool
having a reaction rotor that generates high torque at a relative small size
and weight.
It is still another object of the present invention to provide a turbine rotor
for the
drive shaft of a tool as aforementioned which is relatively lightweight and
compact and
which produces a significant increase in torque over that of the prior art.
Therefore, in accordance with the present application, there is provided a
high
torque turbine rotor for a hand held or spindle mounted pneumatic tool,
comprising: a
rotor body having an inlet attachable to a high pressure air source,
including: a first
annular chamber; a second annular chamber; and a common inner wall, wherein
said first
annular chamber and said second annular chamber are separated by said common
inner
wall; said rotor body being cylindrical and including a plurality of
tangential peripheral
nozzles in fluid communication with said first chamber and said second chamber
for
expelling high pressure air to rotate said rotor body; said inner wall
including a central
bore for receiving an attachment to a drive shaft.
In accordance with the present application, there is further provided a rotor
body to a high
torque turbine rotor, comprising: a cylindrical outer wall, a central inner
wall, and a
central bore; a front surface, including at least one first annular channel
ending in at least
one first arcuate channel ending in at least one first circumferential
opening; said first
annular channel having a first groove for fitting a first perforated barrier;
and a back
surface, including at least one second annular channel ending in at least one
second
arcuate channel ending in at least one second circumferential opening; and
said at least
one second annular channel having a second groove for fitting a second
perforated
barrier.
In accordance with the present application, there is yet further provided a
hand
held pneumatic tool, comprising: a high torque turbine rotor body located
circumferentially around a primary shaft, wherein the turbine rotor body
includes: a front
wall and a back wall adapted for fitting with an inner wall, each including: a
central bore;
the inner wall adapted for fitting with the front wall and the back wall, the
inner wall
including: at least two annular chambers; at least one arcuate chamber
radiating from the
CA 02589985 2010-04-20
outer portion of each annular chamber; a valve o-ring within each annular
chamber; an
annular perforated barrier within each annular chamber located radially
outward from the
valve o-ring; and a central bore.
In accordance with the present application, there is also provided a hand held
pneumatic tool, comprising: a high torque turbine rotor having an outer wall
and an axis
of rotation, means for mounting said turbine rotor for rotation about said
axis of rotation
on a drive shaft, said turbine rotor having an inner wall and at least two
high pressure air
receiving chambers, means for directing pressurized air into the two chambers,
said
turbine rotor having an air passage in each chamber, said air passage ending
in tangential
nozzles in said outer wall of the rotor, said nozzles directing a pressurized
fluid therefrom
to impart rotation to said turbine rotor.
In accordance with the present application, there is yet also provided a high
torque
turbine rotor for a hand held or spindle mounted pneumatic tool, comprising:
means for
generating torque with a cylindrical body having an inlet attachable to a high
pressure air
source, including: means for generating torque in a first chamber of said
body; means for
generating torque in a second chamber of said body; means for directing
pressurized air
into the two chambers; means for separating said first chamber from said
second
chamber; and means connecting said torque generating means to a shaft.
In accordance with the present application, there is additionally provided a
high
torque turbine rotor for a hand held or spindle mounted pneumatic tool,
comprising: an
inlet attachable to a high pressure air source; a first annular chamber; a
first plurality of
tangential peripheral nozzles in communication with said first annular
chamber; a second
annular chamber; a second plurality of tangential peripheral nozzles in
communication
with the second annular chamber; and a common inner wall including a central
bore for
receiving and attachment to a drive shaft, wherein said first annular chamber
and said
second annular chamber are separated by said common inner wall.
In accordance with these and other objects which will become apparent
hereinafter, the instant invention will now be described with particular
reference to the
accompanying drawings.
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BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
Figure 1A is an exploded, perspective view of the preferred embodiment of the
invention.
Figure 113 is a side elevational view of an alternative embodiment of the
invention.
Figure 2 is a cross-sectional, side elevational view of the preferred
embodiment of
the invention.
Figure 3 A is a perspective view of the preferred invention.
Figure 3B is a cross-sectional side elevation view of the preferred invention.
Figure 4 is a partially exploded, sectional perspective view of the preferred
embodiment.
Figure 5 is a perspective view of an alternative embodiment.
Figure 6 is a side elevation view of an alternative embodiment of the
invention.
DETAILED DESCRIPTION OF THE INVENTION
Referring now to the drawings, in particular Figs. IA through 4, the instant
turbine
rotor is illustrated generally at 10. An outside elongated tool housing that
is hand-held
and that encloses the rotor, shaft and bearings is shown in Figure 1B. The
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turbine rotor 10 is used in a hand held or spindle mounted tool as shown in
Figure 1B,
suitable for work such as grinding and polishing.
The turbine rotor body 10 preferably has two separate internal high pressure
air
receiving chambers (a first chamber and a second chamber), formed by a front
wall 12, a
middle inner wall 14 and a back wall 16. The rotor body 10 is generally
cylindrical. The
front wall 12 and the back wall 16 may be identical. The front wall 12, inner
wall 14 and
back wall 16 fit together frictionally and are generally air tight. For
example, the front
wall 12 and the back wall 16 each has a peripheral flange which engages and
extends
over the edge of the periphery of the chamber walls of the middle wall 14. In
the
preferred embodiment, the front wall 12 and the back wall 16 are press fit
against the
middle wall 14. However, the front wall 12 and the back wall 16 and the inner
wall 14
may also be glued together or releasably or permanently attached by other,
equivalent
elements such as a metal clip.
The front wall 12 includes a central threaded bore 18. In the preferred
embodiment, the bore 18 is threaded to correspond with threads on a drive
shaft 60, as
shown in Figures 2, 4 and 5. The drive shaft 60 comprises hollow openings that
serve as
inlets for high pressure air to enter the rotor body 10 chambers to propel the
rotor body
10. Other forms of attachment, with the drive shaft 60, both releasable and
permanent,
are contemplated, such as gluing, welding or frictional engagement with the
drive shaft
60. The front wall 12 and the back wall 16 may be made of plastic, metal or
other
suitable lightweight, rigid material that can be generally airtight. When the
rotor body is
engaged with the shaft, torque produced on the rotor is transferred to the
shaft, causing
the shaft to rotate.
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The common inner wall 14 may also be made from plastic, metal or other
suitable
material. The inner wall 14 includes a threaded central bore 44 to correspond
with
threads on the drive shaft 60 of the tool.
The rotor body 10 in the preferred embodiment includes a governor in each
rotor
housing chamber as described in the `752 patent. Preferably, the governor
comprises a
first annular chamber area 20 on the front surface 48 of the inner wall 14.
Extending
from the outer portion 52 of the first annular chamber 20 is at least one
first arcuate
chamber 24. As show in Figures 1 through 4, in the preferred embodiment, four
(4) first
arcuate chambers 24 are provided which extend from the outer portion 52 of the
first
annular chamber 20 to the circumference 56 of the inner wall 14. The arcuate
chambers
24 open to first circumferential openings 58.
A first resilient valve o-ring 32 is mounted in the first annular chamber 20
to
regulate and restrict the flow of the air from the first annular chamber 20 to
the first
arcuate chamber 24. Extending away from the first valve o-ring 32 is an
annular first
perforated barrier 22. When high pressure air (approximately 90 psi) is
introduced into
the rotor body 10, and the rotor speed reaches a predetermined number of
revolutions per
minute, the valve o-ring 32 deforms against the perforated barrier 22, thereby
restricting
air flow and decreasing the RPMs of the rotor.
As shown in Figure 3, the rotor body 10 includes a second annular chamber 26
on
the rear surface 50 of the inner wall 14. Extending from the outer portion 54
of the
second annular chamber 26 is at least one second arcuate chamber 30. In the
preferred
embodiment, four (4) second arcuate chambers 30 (90 degrees apart) are
provided which
extend from the outer portion 54 of the second annular chamber 26 to the
circumference
56 of the rotor body 10. The second arcuate chamber 30 opens to second
circumferential
openings 62. As illustrated in Figures 1 and 2, the first arcuate chambers 24
and the
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second arcuate chambers 30 are aligned, as are the first and second
circumferential
openings 58, 62. The air passages openings 58, 62 are directionally tangential
to the
cylindrical rotor body 10 and expel high pressure air tangentially to provide
force to
rotate the rotor body 10. However, the alignment of the openings 58, 62 is not
necessary
for operation of the invention.
The second annular chamber 26 also contains a second resilient valve o-ring 34
to
regulate and restrict the flow of the air from the second annular chamber 26
to the second
arcuate chamber 30. Located radially away from the second valve o-ring 34 is
an
annular second perforated barrier 28. Thus, when the air is introduced into
the turbine
rotor 10 and the rotor reaches a predetermined RPM speed, the second resilient
valve
ring 34 deforms against the perforated barrier 28 as the rotor spins, thereby
restricting air
flow and slowing down the rotor.
The valve o-rings 32, 34 are generally resilient and are made of rubber. The
entire turbine rotor 10 (except for the valve o-rings) may be made of rigid
plastic
materials. The turbine rotor 10 bearings do not need lubrication. The
perforated barriers
22, 28 may be made of plastic, metal or other suitable material. Also the
perforated
barriers 22, 28 may be formed intrinsically with the inner wall 14, or
releasably or
permanently attached to the front surface 48 and the rear surface 50 of the
inner wall 14.
The perforated barriers 22, 28 may be a fence-like structure as illustrated in
Figure 1.
However, equivalent structures are also contemplated.
Also in the preferred embodiment, a groove 36 in the front wall 12 and a
corresponding groove 40 in the front surface of the inner wall 14 are situated
so the first
perforated barrier 22 is aligned properly within the turbine rotor body 10.
Similarly, a
groove 38 in the back wall 16 and a corresponding groove 42 in the rear
surface 50 of the
inner wall 14 are situated so the second perforated barrier 28 is aligned
properly in the
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turbine rotor body 10. A single groove may also be used to properly align the
perforated
barrier.
In operation, the preferred embodiment of the turbine rotor 10 works as
follows.
Air under pressure (approximately 90 psi) enters the turbine rotor 10 from the
drive shaft
60 into the central bores 18, 44, 46 in the front wall 12, inner wall 14 and
back wall 16.
The air under pressure enters the first and second annular chambers 20, 26 and
travels
around the first and second valve o-rings 32, 34 through the first and second
perforated
barriers 22, 28 into the first and second arcuate chambers 24, 30. The air
then is forced
under pressure from the arcuate chambers 24, 30 through circumferential
openings 58,
62 in the circumference 56 of the inner wall 14. These peripheral openings
operate as
tangential nozzles, providing air streams generating torquing force to rotate
the turbine.
The reactive force of the air causes the turbine rotor 10 to rotate.
The preferred embodiment includes a revolutions per minute ("RPM") governor
described in U.S. Patent No. 4,776,752 in each drive chamber. The resilient
deformation
of the valve o-rings 32, 34 against the perforated barriers 22, 28 caused by
centrifugal
force forces the turbine 10 to turn at a predetennined, somewhat constant
rate. As the
turbine rotor 10 rotates at a high RPM speed, the first and second valve o-
rings 32, 34
deform, pressing against the perforations of the first and second perforated
barriers 22,
28. The deformation of the valve o-rings 32, 34 restricts air flow through the
perforations in the barriers 22, 28, thereby reducing rotational forces.
Eventually
equilibrium is reached whereby a constant speed of rotation for the turbine
rotor 10 is
achieved.
The torque of the turbine rotor 10 in the present invention is greatly
increased
over that of prior art rotors. For example, when compared to two stacked
turbine rotors,
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the present invention provides less weight, vibration, chatter and run through
of the air
and fewer moving parts that may wear.
Figures 5 and 6 illustrate an alternative embodiment of the invention. As
shown
in Figures 5 and 6 the rotor housing is narrowed, for less weight and a
further increase in
torque.
The design of the turbine rotor 10 with multiple annular chambers and multiple
arcuate chambers provides an increase in torque from prior art air turbines
without a
significant increase in the weight of the spindle apparatus. Moreover, there
is less
vibration than would be if single turbine rotors were stacked on top of each
other. It is
also contemplated in an alternative embodiment that additional annular
chambers and
arcuate chambers could be formed between in the first and second chambers.
These
additional chambers may have valve o-rings and perforated barriers as
described herein
for governing the RPMs. Furthermore, although the invention has been described
to
work with air, other gases are also contemplated for other applications.
The instant invention has been shown and described herein in what is
considered
to be the most practical and preferred embodiment. It is recognized, however,
that
departures may be made therefrom within the scope of the invention and that
obvious
modifications will occur to a person skilled in the art.
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