Note: Descriptions are shown in the official language in which they were submitted.
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CENTRIFUGAL FORC~ DRIVE M~TN~
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to drive mechanisms and,
more particularly, to drive mechanisms for converting a
rotary motion into a linear force in a particular direction.
2. Pescription of the Prior Art
It is quite common in the m~hAn;cal arts to convert a
rotary motion into a linear force. For example, in the pile
lo driving area, it is desirable to translate a rotary force
into a downward force which drives the pile into the ground.
In the simplest version of a pile driver, a large weight is
lifted vertically and then dropped onto the pile to drive it
into the ground.
During the last 25 years, vibratory
driver/extractors have come into wide use in the pile
driving industry. The vibratory force is generated by one
or more pairs of identical eccentrics having parallel axes
of rotation. The pair of eccentrics rotate in opposite
directions and are generally connected by gears so that they
rotate in synchrony at the same speed. Such eccentrics are
typically rotated by an electric motor or hydraulic drive
unit.
These vibratory driver/extractors are primarily
used on non-displacement piles, such as steel sheet piles,
H-piles, open-end pipe piles and caissons. Conventional
vibratory driver/extractors generate very high driving
forces, from twenty to several hundred tons, but the force
is actually reversed twenty to thirty times per second and
so it does not really drive or extract the pile. A
~ vibrating frame clamps onto the pile with a hydraulic clamp
and the pile is vibrated up and down, generally on the order
of 1/4-3/4 of an inch, and at a frequency between 1,000-
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2,000 cpm. This vibration breaks the frictional bond t
between the pile and the soil. The weight of the apparatus
causes the pile to penetrate into the soil overcoming only
the point resistance which is small on a non-displacement
pile. In extraction, the vibration breaks the soil friction
and the pile is lifted out of the ground by raising the
extractor with a crane hammer line.
Vibratory apparatus may also be used to compact
soil and other material.
Conventional vibratory driver/extractors rotate
the eccentrics and transmit the driving force through axles
mounted on roller bearings. Because of the extremely high
stresses in these bearings, they are short-lived and a
constant source of breakdowns. Vibratory driver/extractors
currently in use typically generate a driving force in one
direction, and then generate a fraction of a second later an
equal force in the opposite direction.
It is an object of this invention to provide a
machine which will develop, in a simple and durable
arrangement, a near constant force in one direction and
little or no force in the opposite direction. It is also an
object of the present invention to develop such a device
which will have particular utility in driving piles, but
will also have other applications where generating a uni-
directional force is desirable.
SUMMARY OF THE INVENTION
I provide a centrifugal force drive machine for
generating a force in a controlled direction. The machine
includes a machine frame having a shaft mounted thereto.
The shaft is rotatable about its axis. Power means are
provided in driving connection to the shaft and are operable
to rotate the shaft about its axis. At least one mass is
mounted on the shaft for rotation therewith. Each mass has
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a center of gravity which is movable radially with respect
to the shaft between a position in which the mass is
rotationally balanced about the shaft and a position in
which the mass is rotationally unbalanced about the shaft.
A control member is provided in operative connection between
the frame and the masses to constrain the mass to move
between a balanced position and an unbalanced position
during each revolution of the masses. The center of gravity
of each mass preferably travels in a generally oval path
between the center of rotation of the shaft and a point
spaced from the center of rotation in the controlled
direction, thereby generating the desired force in the
controlled direction.
The control member preferably includes a generally
oval opening in the frame bounded by a track. The track is
positioned to engage each mass for at least a portion of
each revolution of each mass. The center of the track is
spaced from the center of rotation in the controlled
direction. In a preferred embodiment, the track is
adjustable, thereby permitting variation of the controlled
direction.
In one embodiment of this invention, one elongated
mass is mounted on the shaft. The mass has a roller at each
end to engage the control member. The center of gravity of
the mass is located midway between the rollers. The control
member includes a track having a first curved portion and
second curved portion. The first curved portion is
generally semi-circular, with a constant radius and a center
that is offset from the center of rotation in the controlled
- 30 direction. The second portion has a changing radius of
curvature, such that the rollers of the mass are in
juxtaposition to the track during each revolution of the
mass.
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Another embcdiment of this invention provides two
elongated masses of the type described above. The masses
are mounted generally perpendicular to one another. The
control member includes a track of the type described above,
such that the rollers of both masses are in juxtaposition to
the track during each revolution of the masses.
Yet another embodiment of this invention includes
a machine frame having a shaft mounted thereto. The shaft
is rotatable about an axis. Power means are provided in
driving connection to the shaft to rotate the shaft about
its axis. A mass is mounted on the shaft for rotation with
the shaft at a constant radius. A second mass is mounted on
the shaft for rotation with the shaft at a variable radius
of rotation. A control member in operative connection
between the second mass and the frame constrains the second
mass to move so that the center of gravity thereof travels
in a generally continuous path between a position with the
same radius as the radius of rotation of the center of
gravity of the first mass and a position in which the radius
of rotation of the center of gravity of the second mass is
different from that of the first mass. When the path of the
center of gravity of the second mass has the same radius as
the radius of rotation as the center of gravity of the first
mass, the eccentric moment is balanced or zero. When the
path of the center of gravity of the second mass is
different from the radius of rotation of the center of
gravity of the first mass, the eccentric moment results in
creation of force in the controlled direction.
Another embodiment of this invention includes a
machine frame having a shaft mounted thereto. The shaft is
rotatable about its axis. Power means are provided in
driving connection to the shaft and are operable to rotate
the shaft about its axis. A mass in fixed rotational
connection to the shaft and in unrestricted radial
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connection to the shaft is provided. The mass has a center
of gravity that is eccentric generally in the controlled
direction about the axis for at least one half of each
revolution of the mass and concentric with the axis for at
least part of each revolution of the mass. Control means
are provided forming an inwardly facing surface surrounding
the axis of the shaft and being of changing radius. The
control means limits outward movement of the mass and
transfers centrifugal force generated by rotation of the
mass to the frame.
The objects discussed above as well as other
details, objects and advantages of my invention will become
more apparent as the following detailed description
proceeds.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is an elevational view of an embodiment
of the centrifugal force drive machine of this invention
with the mass shown in a balanced position about the center
of rotation.
Figure 2 is a cross-sectional view of the
embodiment of this invention as shown in Figure 1 and taken
through line 2-2 of Figure 1.
Figure 3 is an elevational view of the embodiment
of this invention shown in Figure 1 with the masses shown in
an unbalanced position about the center of rotation.
Figure 4 is a cross-sectional view of the
embodiment of this invention shown in Figure 3 and taken
through line 4-4 of Figure 3.
~ Figure 5 is an elevational view of another
embodiment of the centrifugal force drive machine of this
invention.
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Figure 6A is a partial cross-sectional view of the
embodiment of this invention shown in Figure 5 and taken
through line 6A-6A of Figure 5.
Figure 6B is a partial cross-sectional view of the
embodiment of this invention shown in Figure 5 and taken
through line 6B-6B of Figure 5.
Figure 7 is an elevational view of another
embodiment of the centrifugal force drive machine of this
invention.
Figure 8 is a cross-sectional view of the
embodiment of this invention shown in Figure 7 and taken
through line 8-8 of Figure 7.
Figure 9 is an elevational view of another
embodiment of the centrifugal force drive machine of this
invention.
Figure 10 is a cross-sectional view of the
embodiment of this invention shown in Figure 9 and taken
through line 10-10 of Figure 9.
Figure 11 is an elevational view of another
embodiment of the centrifugal force drive machine of this
invention.
Figure 12 is a cross-sectional view of the
embodiment of this invention shown in Figure 11 and taken
through line 12-12 of Figure 11.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
Referring to Figures 1-4, there is shown an
embodiment of the centrifugal force drive machine of this
invention. For purposes of illustration, the controlled
direction in which the desired force is to be generated is
represented by an arrow marked CD. The centrifugal force
drive machine includes machine frame 2. Shaft 4 is mounted
to machine frame 2. Shaft 4 is rotatable about its axis A.
Power means 6 are provided in driving connection to shaft 4
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and are operable to rotate shaft 4 about its axis A. Power means 6 may rotate shaft
4 using direct drive, gear drive, belt drive, chain drive or any other suitable drive
arrangement known to those skilled in the art. Mass 8 is mounted on shaft 4 for
rotation about a center of rotation CR. Mass 8 is preferably elongated and has a roller
10, 12 mounted at each end thereof. Control member 14 is in operable connection
between frame 2 and mass 8. Rollers 10, 12 are positioned to engage control member
14 during each revolution of mass 8. The center of gravity CG of mass 8 is located
generally midway between rollers 10, 12.
Control member 14 includes an opening, indicated generally by the
number 16, in frame 2. Opening 16 is bounded by an inwardly facing, generally
continuous track 18. Track 18 has a first curved portion 20 and a second curved
portion 22. First portion 20 is generally semi-circular and has a generally constant
radius. The center of first portion 20 is offset in a controlled direction from the center
of rotation CR. Second portion 22 has a ch~n~ing radius of curvature. Dotted arc 23
represents where the curve of semi-circular first portion 20 would be located if it were
continued through the area bounded by second portion 22. Track 18 is preferably
adjustably mounted to frame 2 to permit the controlled direction CD to be varied as
desired.
Mass 8 is movable radially with respect to shaft 4. As mass 8 rotates,
it moves radially from a position in which it is rotationally balanced about the shaft
(shown in Figure 1) and a position in which it is rotationally llnk~l~nced about the shaft
(shown in Figure 3). Referring more particularly to Figure 2, shaft 4 is provided with
enlarged portion 24 having a transverse opening 26 therethrough. Mass 8 is received
in opening 26. Mass 8 includes pins 28 which are received into slots 30, which are
part of opening 26. Mass 8 may then move radially within
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opening 26 guided by pins 28. Alternatively, other suitable
means known to those skilled in the art for permitting
radial movement of mass 8 may be utilized.
As mass 8 revolves, the centrifugal force
resulting from the rotation moves the mass radially outward.
The extent of the radial movement is limited by the
engagement of rollers 10, 12 with track 18.
Referring more particularly to Figure 1, the
apparatus of this embodiment is shown with mass 8 in a
rotationally balanced position. Center of gravity CG of
mass 8 is in generally the same location as the center of
rotation CR of mass 8. As mass 8 rotates with shaft 4, mass
8 will move radially outward, constrained by the engagement
o~ rollers lo, 12 and track 18. Rotation and radial
movement of mass 8 causes the center of gravity of mass 8 to
move in a path P that is generally the same shape as curved
track 18. Path P extends generally in the controlled
direction from the center of rotation CR. As mass 8 rotates
from the position shown in Figure 1, it exerts a component
of force in the controlled direction CD. As mass 8 rotates
toward the position shown in Figure 3, the force in the
controlled direction increases. When mass 8 reaches the
position shown in Figure 3, the force in the controlled
direction is at is maximum. Further rotation returns the
mass to a position similar to that shown in Figure 1 and the
magnitude of force in the controlled direction decreases
until mass 8 is once again rotatably balanced about center
of rotation CR and force in the controlled direction e~uals
zero. This cycle is repeated twice during each revolution.
The maximum force in the controlled direction is generated
each time the mass reaches the position shown in Figure 3.
Because the mass has two identical ends, two such forces
will be generated during each revolution of the mass 8.
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Referring again to Figures 1 and 2, the shape of
control means 14 of this embodiment enables the rollers 10,
12 to be in juxtaposition to track 18 during each entire
revolution of mass 8. Keeping mass 8 in contact with
control means 14 at all times during its revolution reduces
the likelihood that damage could occur from the mass
recontacting the control member after having travelled a
portion of the rotation not in contact with the control
member.
A machine of the embodiment of Figures 1-4 having
a mass weighing 1200 lbs that includes two rollers 12 inches
in diameter by 12 inches thick and traveling on a track
having a nominal diameter of 45 inches with the center being
offset by 6 inches and rotating at 1000 rpm would be
expected to provide a force of approximately 115 tons. The
same device rotating at 2000 rpm would be expected to
generate a force of approximately 460 tons. This device
would be particularly suitable for use as a pile driver. A
machine of the embodiment of Figures 1-4 having a mass
weighing 1800 lbs and having two rollers with diameters of
16 inches by 10 inches thick, traveling a track having a
nominal diameter of 60 inches and a center offset by 10
inches would be expected to provide a force of approximately
287 tons when rotating at 1000 rpm and approximately 1150
tons at 2000 rpm. This configuration would be particularly
suitable as a compactor.
Referring now to Figures 5 and 6, there is shown
another embodiment of the centrifugal force drive machine o~f
this invention. This embodiment is virtually identical to
that set forth above with respect to Figures 1-4, except
that two elongated mass 40, 42 are provided. Each mass 40,
- 42 has at least one roller, 44, 46, 48, 50 mounted on each
end thereof. Each roller is positioned to engage control
member 14. The center of gravity CG of each mass 40, 42 is
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located generally midway between the rollers. Mass 40 is
positioned generally perpendicular to mass 42.
Masses 40, 42 are mounted on shaft 4 for rotatio~
therewith. The center of gravity CG of each mass 40, 42 is
radially movable with respect to shaft 4 between a position
in which the mass is radially balanced about shaft 4 and a
position in which the mass is radially unbalanced about the
shaft. Masses 40, 42 are mounted to shaft 4 to be
independently radially moveable.
The configuration of track 18 is as set forth
above with respect to Figures 1-4. This configuration
permits all of the rollers on masses 40, 42 to remain in
contact with track 18 during each entire revolution of the
masses 40, 42. Track 18 is preferably adjustably mounted to
frame 2 to permit variation of the controlled direction CD.
The use of two double-ended masses 40, 42 mounted
perpendicular to one another for rotation with the shaft 4
results in the generation of four separate forces in the
controlled direction during each revolution of shaft 4. The
use of two masses also provides more counterbalance during
rotation, thereby providing even greater reduction in the
unbalanced lateral forces unloaded on the drive means.
Referring to Figure 7 and 8, there is shown
another embodiment of the centrifugal force drive machine of
this invention. This embodiment includes machine frame 70
having a shaft 72 mounted thereto. Shaft 72 is rotatable
about its axis. Power means 74 provided in driving
connection to shaft 72 and are operable to rotate shaft 72
about its axis A. Power means 74 may rotate shaft 72 using
direct drive, gear drive, belt drive, chain drive or any
other suitable drive arrangement known to those skilled in
the art. A mass 76 is mounted on shaft 72 for rotation with
the shaft at a constant radius. A second mass 78 is mounted
on shaft 72 for rotation therewith at a variable radius of
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rotation. A pair of brackets 79 connect the masses 76, 78
to one another and to shaft 72. A control member 80 in
operable connection between second mass 78 and frame 70
constrains the second mass 78 to move so that the center of
gravity thereof travels between a position with the same
radius of rotation as the center of gravity of mass 76 and a
position wherein the radius of rotation is different from
the radius of rotation of the center of gravity of mass 76.
When the radius of rotation of the center of gravity of
lo second mass 78 is the same as the radius of rotation of the
center of gravity of first mass 76, no eccentric moment is
produced. When the radius of rotation of the center of
gravity of second mass 78 is different from the radius of
rotation of the center of gravity of mass 76 an eccentric
moment results that increases the centrifugal force
generated in that part of the revolution. The centrifugal
force generated when the radius of rotation of the center of
gravity of mass 78 is different from that of 76 is
transferred to frame 70 through control member 80 to
generate a force in the controlled direction.
In a preferred embodiment, mass 78 includes roller
82 for engaging control member 80. Roller 82 is radially
movable within slot 84 in bracket 79. Roller 82 is
rotatable about axle 86 which is received into and is
radially movable within slot 84. Control member 80
preferably includes an opening in frame 70 mounted by a
generally oval track 88. Track 88 is offset in the
controlled direction CD from the center of rotation CR of
shaft 72. Track 88 is preferably adjustably mounted to
frame 70 to permit variation of controlled direction CD. As
shaft 72 and masses 76, 78 rotate, roller 82 engages track
- 88. When mass 78 travels through the portion 90 of track 88
which lies in the controlled direction CD, the radius of
rotation of mass 78 becomes larger than the radius of
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rotation of mass 76 and rotation becomes unbalanced. This
unbalanced rotation produces an eccentric moment that
generates a centrifugal force having a component in the
controlled direction which is transferred to the frame, as
discussed above. A force is thereby generated in the
controlled direction. When mass 78 travels over the
remainder of track 88, the center of rotation of masses 76,
78 are substantially the same and rotation is balanced.
With this embodiment, one impulse or force is generated in
the controlled direction during each revolution of shaft 72.
Referring now to Figures 9 and 10, there is shown
yet another embodiment of this invention. This embodiment
is similar to the embodiment shown in Figures 7 and 8. The
device includes frame 70, rotatable shaft 72, power means 74
and control member 80, which includes track 88. Shaft 72
includes an offset portion 92. Offset portion 92 of shaft
72 forms mass 76, which is mounted for rotation with shaft
72 at a fixed radius of rotation. Mass 78, which is
radially movable with respect to shaft 72, includes roller
82 mounted on axle 86. Axle 86 is received into slots 94 in
shaft 72 to facilitate radial movement of roller 82 with
respect to shaft 72.
Rotation of the fixed mass 76 with movable mass 78
produces a flywheel effect of storing energy for one half of
each revolution. The flywheel effect reduces the amount of
power needed to maintain rotation of the masses and enables
larger masses to be used, thereby providing greater forces
in the controlled direction.
In operation, this embodiment works in
substantially the same way as the embodiment shown in
Figures 7 and 8. With this embodiment, as with the
embodiment of Figures 7 and 8, one force is generated in the
controlled direction during each rotation of shaft 72.
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Because larger masses may be used with this embodiment,
greater forces may be generated using the same power input.
Referring now to Figures 11 and 12, there is shown
another embodiment of this invention. This embodiment
includes machine frame 100 having shaft 102 mounted thereto.
Shaft 102 is rotatable about its axis A. Power means 104
are provided in driving connection to shaft 102 and are
operable to rotate shaft 102 about its axis A. Power means
104 may rotate shaft 102 using direct drive, gear drive,
belt drive, chain drive or any other suitable drive
arrangement known to those skilled in the art. Mass 106 is
mounted in fixed rotational connection to shaft 102 and in
unrestricted radial connection to shaft 102. Mass 106 has a
center of gravity CG that is eccentric generally in the
controlled direction with respect to axis A for at least one
half of each revolution thereof and concentric with axis A
for at least part of each revolution. Control member 108
forming an inwardly facing surface surrounding the axis A of
shaft 102 and being of changing radius is provided. Control
member 108 limits outward radial movement of mass 106 and
transfers centrifugal force generated by rotation of the
mass to the frame. Control member 108 is preferably
adjustably mounted to frame 100 to permit variation of
controlled direction CD as desired. Spring means 110 are
positioned between mass 106 and shaft 102 to urge mass 106
radially outward. Mass 106 includes roller 112 preferably
positioned to engage control member 108 during each entire
revolution.
Control member 108 includes a generally oval track
- 30 having a center offset from the axis A of shaft 102 in the
controlled direction.
As shaft 102 and mass 106 rotate, engagement of
roller 112 and control member 108 restrain radial movement
of mass 106. As mass 106 rotates and radial movement
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thereof is constrained, the center of gravity CG of the mass
106 travels in the path P that is generally the same shape
as the shape of control member 108. When roller 112 is in t
the portion 114 of control member 108 that is in the
controlled direction, the center of gravity CG of the mass
is offset in the controlled direction from the axis A of
shaft 102 and rotation becomes unbalanced. The centrifugal
force generated by the unbalanced rotation of mass 106 is
transferred to the frame through control member 108, thereby
generating a force in the controlled direction CD.
In this embodiment, mass 106 is provided with a
threaded plug 116 which is positioned generally opposite
roller 112. Threaded plug 116 can be radially adjusted to
fine tune this apparatus. Adjusting the position of
threaded plug 116 will change the center of gravity of mass
106, thereby enabling the user to make adjustments which
ensure that the center of gravity of mass 106 travels on the
desired path P.
While I have illustrated and described certain
present preferred embodiments of my invention, it is to be
understood that I do not limit myself thereto and that the
invention may be otherwise and variously practiced within
the scope of the following claims.
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