Variable eccentric vibration generating mechanism

A rotatable vibration generating mechanism includes a movable eccentric weight. Said weight is variably positioned to change the eccentricity of the mechanism by the controlled flow of fluid (liquid or air) when the mechanism is stationary or rotating. More than one weight may be used and a combination of movable parts may be used as a compound movable weight. The fluid pressure resisting the movement of the weight is recorded and thus the centrifugal force generated is known through calculation, since the weight, shape, geometric configuration, and positioning of the eccentric weight is known. The centrifugal force can be changed without changing the rotating speed through the use of valve means regulating fluid flow to change the position of the eccentric weight. Pressure sensitive controls may be adapted to the valve means to make the flow control automatic so that the centrifugal force can be held constant or limited through a specified vibrational speed range. A choice of a variety of fluid pressure source means may be used to force the movement of the weight.

DETAILED DESCRIPTION 
Referring now to the drawings, FIGS. 1 and 2 show the same variable 
eccentric mechanism 10. The mechanism has a cylinder-like chamber 11 
fastened to or being a part with shaft means 12. The shaft means has a 
drive means 13 shown in this embodiment as an integral splined shaft. The 
shaft means is journaled at 14 and 15 for the mounting of bearings. 
The movable weight 16 is shown in an intermediate eccentric position. It is 
positioned and held by the fluid 17. Said weight is further positioned by 
the seals 18 and 19 which engage the weight and contact the interior 
surface of the chamber 11. 
The minimum eccentricity of the mechanism is accomplished when said weight 
is forced against flange 20 of top cap 21. The eccentricity in this 
condition approaches zero. The cap 2 is equipped a breather 22 to avoid a 
pressure or vacuum resistance to the movement of the weight 16. The cap is 
fastened to the chamber by common means. 
The maximum eccentricity of the mechanism is accomplished when said weight 
is forced against the flange 23 of the bottom cap 24 by gravity and/or 
centrifugal force. 
The fluid 17 that forces and allows movement of the weight enters and 
leaves the chamber through conduit 25 which is fastened with common 
fittings to the bottom cap 24 and the bearing journal passage 26. Said 
passage is connected to rotary coupling 27 through the connecting part 28 
that is fastened by common means to the shaft. 
Fluid is transferred to and from the rotary coupling through the supply 
line 29. A pressure gauge 30 is installed by common means in the supply 
line. The reading on the gauge provides the unit pressure in the supply 
line, rotary coupling, bearing journal passage, conduit and chamber. 
Valve means 31 is located in the supply line to stop the fluid flow and 
regulate the amount of fluid flow in or out of said chamber through the 
means provided. 
Pressure source 32 provides pressurized fluid as required through the means 
provided to change the eccentricity. 
In FIGS. 1 and 2 a second pressure source 33 is shown to be connected to a 
circuit similar to the one described previously but without a chamber and 
weight. Pressure source 33 provides pressurized fluid as required to 
change the eccentricity of another variable eccentric mechanism similar to 
the one shown. Fluid is furnished as required to the valve means 34, 
supply line 35, pressure gauge 36, fluid coupling 37 through connecting 
part 38 to bearing journal passage 39, through conduit 40 and into bearing 
journal passage 41. Plug 42 closes this passage when fluid flow is not 
required to change the eccentricity of another similar variable eccentric 
mechanism that is connected by common means to turn synchronously with the 
embodiment shown. 
With the second pressure source in mind let us refer to FIGS. 3 and 4. 
These show a variable eccentric mechanism 43 with two cylinder-like 
chambers 44 and 45, with a weight that is not shown disposed in each 
chamber. One pressure source 46, through the circuit provided, moves the 
weight in chamber 44 and the second pressure source 47 moves the weight in 
the second chamber 45. The circuitry is the same in embodiment 43 as in 10 
except that second pressure source is used to move a second weight within 
the same mechanism rather than being passed on to a separate variable 
eccentric mechanism. 
FIGS. 1 and 2 show the preferred embodiment. It is preferred because of the 
versatility evident in the ability to pass control fluid to and from 
another vibration generating mechanism. Two vibration generating 
mechanisms often have an advantage because they can develop a synchronized 
force whose effect can be divided between four supporting bearings rather 
than two. The obvious advantage is an increase in the life of the 
bearings. When bearing loads and bearing life are not a problem and enough 
centrifugal force can be developed from a single movable weight a single 
passage through one bearing housing and a single rotary coupling would be 
a more economical mechanism to produce. In that event, pressure source 33, 
valve means 34, supply line 35, gauge means 36, rotary coupling 37 with 
its connecting part 38, passage 39, conduit 40, passage 41 and plug 42 
would not be used. 
In the zero eccentricity mode the mechanism is balanced by the distribution 
of weight of the total mechanism. The center of gravity of the weight is 
slightly below the center line of the bearing journals so that it will 
tend to move radially outward when the shaft is rotating. 
It is noted in FIG. 2 that the top cap 21 is much thicker than the bottom 
cap 24. In this manner it not only serves as a stop in the zero 
eccentricity mode but counter balances the weight of the chamber that 
extends further below than above the centerline of the bearing journals. 
The eccentricity is increased by using the valve means to allow fluid to 
flow from the chamber. This allows the weight to assume a more off center 
position. To decrease the eccentricity the valve means is used to regulate 
a flow of pressurized fluid into the chamber. This forces the weight 
toward the center line of the bearing journals. 
When the eccentricity is increased at any given rotational speed the 
centrifugal force and amplitude are increased. Conversely when the 
eccentricity is decreased at any given rotational speed the centrifugal 
force and amplitude are decreased. Vibrational amplitude is adjustable 
from zero to a predetermined value at all effective rotational speeds. 
This change in force will register on the pressure gauge as an increase or 
decrease in pressure. Since the shape of the movable weight is known the 
pressure will indicate the force through direct conversion. Force = 
Pressure x Area. The weight is offset from the axis of rotation even when 
the mechanism is balanced. Pressure will always be generated except when 
the weight is in its maximum eccentric position and its movement is 
resisted by a mechanical stop rather than by the presence of fluid and 
fluid pressure. The fluid pressure will be zero under that condition. At 
that point the eccentricity of the center of gravity of the movable weight 
is known and the centrifugal force will vary directly with the second 
power of the rotational speed. The pressure source will be chosen to be 
able to develop adequate pressure to force the weight away from the stop 
back toward the axis of rotation when a reduction in force and 
eccentricity is desired. In larger mechanisms fluid weight may be 
significant in calculating the generated centrifugal force. The weight of 
fluid will always be considered to assure a balanced mechanism in the zero 
eccentricity mode. 
Turning to FIG. 5 there is shown a modification of the mechanism 10 shown 
in FIGS. 1 and 2. The mechanism 10a incorporates a simple rotary fluid 
coupling 50 fastened by connecting part 51 to the bearing journal 15 end 
in place of the duplex rotary fluid coupling made up of parts 27, 28, 37, 
and 38 shown in FIGS. 1 and 2. The simple rotary fluid coupling allows for 
a single fluid circuit to pass to the mechanism 10a while the duplex 
rotary fluid coupling allows for two separate fluid circuits to pass to 
mechanism 10. 
Continuing in FIG. 5 the mechanism 10a incorporates single supply line 29 
connected to pressure source 32, valve means 31, pressure gauge 30 and 
body of the rotary coupling 50. Control means 52, an optional device, is 
shown in dashed lines, as a part of and adapted to valve means 31. This 
control means is pressure sensitive to the pressure in the cylinder 
through the connecting circuit. The control operates the valve means to 
allow flow in or out of the cylinder. This flow maintains or limits the 
pressure in the circuit by positioning the movable weight. The control is 
readily adjustable either manually or by remote control means. 
The pressure source 32 is one of various types common in the art that 
supplies pressurized fluid as required to force the weight to a less 
eccentric position. 
Continuing again in FIG. 5 the mechanism contains movable weight 16, and 
other features and parts found in the mechanism 10 shown in FIGS. 1 and 2. 
The zero eccentricity mode and the maximum eccentricity are achieved in 
the same manner as previously described. 
The mechanism 10a shown in FIG. 5 and subsequent mechanisms show the 
cylinder means as an integral part of a cast or forged shaft body. It is 
understood to those skilled in the art that the shaft body may be a 
weldment including the cylinder means. The cylinder means may also be a 
separate replaceable piece commonly fastened to a cast, forged or 
fabricated shaft body. 
The mechanism is drivenly rotated through drive means 13. Drive means 13 is 
shown as an external spline. Drive means such as internal splines, shaft 
and key or other conventional structure may be used. 
FIG. 6 describes a mechanism 60 which includes a compound movable eccentric 
weight. Piston 61, seals 18 and 19, piston rod 62, and exterior weight 63 
comprise the compound movable eccentric weight. When the piston 61 is 
located against the flange 20 of cap 21 the mechanism is essentially 
balanced and the eccentricity is zero. The center of gravity of the 
movable weight at the same time is offset towards the cap 24 and flange 
66. Flange 66 acts as a stop to limit the travel of the piston which 
limits the maximum eccentricity. Because the center of gravity of the 
movable weight is offset it tends to move in the direction of the cap 24. 
This movement is resisted and restricted by fluid 17 that fills the 
cylinder below the piston 61 and around the rod 62 as shown. The weight 
and location of the fluid is considered in calculating balance and 
centrifugal force. The fluid will restrict the movement until valve means 
31 allows fluid to flow from the cylinder 11 through the bearing journal 
passage 26, through the rotary coupling made of parts 50 and 51, and 
supply line 29. 
In the mechanism 60 shown in FIG. 6 the fluid 17 enters and leaves the 
cylinder 11 through the bearing journal passage 26 at a point below the 
top of flange 66. 
Control means 52, an optional device, is shown in dashed lines, as a part 
of and adapted to valve means 31. This control means is pressure sensitive 
to the pressure in the cylinder through the connecting circuit. The 
control operates the valve means to allow flow in or out of the cylinder. 
This flow maintains or limits the pressure in the circuit by positioning 
the movable weight. The control is readily adjustable either manually or 
by remote control means. 
The pressure source 32 is one of various types common in the art that 
supplies pressurized fluid as required to force the weight to a less 
eccentric position. 
The eccentricity of the compound weight is adjustable in the same manner as 
the eccentricity of the weights in mechanism 10 shown in FIGS. 1 and 2. 
The exterior weight 63 and part of the piston rod 62 are shown in broken 
lines in a second position to depict a more eccentric position. 
The radial movement of the compound weight is slidingly guided by the 
piston seals 18 and 19 fixed to piston 61 sliding in the cylinder 11 and 
the sliding contact between the piston rod 62 and the packing 65 fixed in 
the packing flange 64 which is fastened to cap 24. 
The breather 22 in cap 21 avoids a pressure or vacuum resistance to 
movement of this piston 61 with seals 18 and 19 within the cylinder. 
The mechanism is drivenly rotated through drive means 13. Drive means 13 is 
shown as an external spline. Drive means such as internal splines, shaft 
and key or other conventional structure may be used. 
FIGS. 7, 8 and 9 picture another embodiment of the invention. The mechanism 
70 has many primary parts that are like those in mechanism 60. Mechanism 
70 has an elongated U shaped shaft body 12 which accomodates two cylinders 
11. An elongated exterior weight 72 shown in FIGS. 8 and 9 is fastened to 
the piston rods 62 from each of the two cylinders. The fluid circuitry is 
the same except that the two cylinders are fluidly connected by conduit 71 
and common fittings (not itemized) shown in FIG. 7. The cylinder 11 in 
proximity to the rotary coupling 50 is connected with the pressure source 
32 as in mechanism 60. 
FIG. 9 shows linkage 73 (not shown in FIGS. 7 and 8) that is used in 
synchronizing the movement of the piston rods 62. The action is obvious to 
those skilled in the art. The linkage comprises bell cranks pivotly pin 
connected to the shaft body 12 with pivotal connections to push-pull rods 
and with the rods being pivotly connected to brackets on the exterior 
weight. Even though the pressures in the two cylinders are intended to be 
the same through a common circuit variable resistances between the seals 
and cylinders and between packings and rods in the sliding action would 
tend to make one rod move more easily than the other and the elongated 
weight could move in and out in a position not parallel to the axis of 
rotation and offer an unpredictable action. It will be understood by those 
skilled in the art that other apparatus such as gearing, pulleys and cable 
etc. could be used to synchronize the movement of the rods 62. 
The position of the compound movable weight, which includes two sets of 
seals, pistons, piston rods and exterior weight 72, is controlled through 
the flow of fluid in and out of the piston rod ends of the cylinders. The 
flow in and out of the cylinders is controlled by valve means 31 through 
supply line 29. The pressure sensitive control 52, shown in dashed lines 
as an option attached to valve means 31, may be used to actuate the valve 
means 31 controlling the flow of fluid to position the movable weight and 
regulate the generated centrifugal force. 
The pressure source 32 is one of various types common in the art that 
supplies pressurized fluid as required to force the weight to a less 
eccentric position. 
One of the objectives of the mechanism shown in this embodiment is to 
provide an elongated mechanism to vibrate a body that has an elongated 
distance between means to mount bearings in support of the mechanism. 
Another objective is to divide the resistance to the generated force 
between two cylinders. In this way the maximum pressure in the cylinders 
can be halved and the beam loading of the shaft body is such to reduce the 
maximum bending moment, stresses and deflection of the shaft body. It is 
understood that more than two cylinders could be used in this embodiment 
to increase the generated force rating and/or to reduce the fluid pressure 
requirement. 
The mechanism is drivenly rotated through drive means 13. Drive means 13 is 
shown as an external spline. Drive means such as internal splines, shaft 
and key or other conventional structure may be used. 
FIG. 10 depicts another embodiment of the invention. Mechanism 80 shows a 
cylinder with attaching parts as the movable eccentric weight. The 
cylinder is made of barrel 81, cap 24, packing gland 64, packing 65, cap 
21 and breather 22. The cylinder is shown in the zero eccentricity mode. 
The mechanism is essentially balanced with the cylinder in this position. 
The center of gravity of the cylinder however is slightly off center in 
the direction of the piston and when the mechanism is rotated it tends to 
move outwardly in said direction. The broken lines show the cap and 
breather end when the center of gravity of the cylinder is in a more off 
center location. 
Piston rod 82 is shown fixed to the integral cap of cylinder means 11. It 
is understood that the cap could be a separate part fastened to the open 
ended cylinder. The cylinder means 11 is shown as an integral part of 
shaft body 12. It is understood further that this cylinder means could be 
a separate part fastened to the shaft body as discussed previously herein. 
The rod 82 is shown threadly fastened to piston 61. The rod, piston and 
seals have a fixed position. When the flow of the fluid 17 is allowed out 
of the cylinder body by valve means 31 through the piston rod fluid 
passage 83, conduit 25, bearing journal passage 26, connecting part 51, 
rotary coupling 50 and supply line 29 the cylinder which is the movable 
weight described earlier moves outwardly slidingly guided by the packing 
65 on the piston rod 82, the seals 18 and 19 on the interior of the 
cylinder barrel 81 and the liner 84 on the outside of the cylinder barrel. 
The liner 84 is a tight fit in the cylinder means 11 and a loose fit about 
the outside of the barrel. Other means of construction could be used. The 
outside of the cylinder barrel 81 or the inside of the cylinder means 11, 
or both could be treated with an anti-friction coating instead of using 
liner 84. The choice of liner or protective coating is left to the 
designer in evaluating the individual application. 
In order to decrease the centrifugal force for any given vibrational speed 
fluid from the pressure source is directed through the valve means 31, 
supply line 29, rotary coupling 50, connecting part 51, bearing journal 
passage 26, conduit 25, piston rod passage 83 into the cylinder which is 
the movable weight. The weight and location of the fluid is considered in 
calculating balance and centrifugal force. The fluid pressure against the 
cap 24, packing gland 64, packing 65 moves the weight inward towards the 
zero eccentricity mode in a regulated manner. 
The pressure recorded by gauge means 30 is related directly to the 
centrifugal force being generated as the mechanism is rotated by the 
formula, Force = Pressure .times. Area. The Area in this instance is the 
surface of cap 24, packing gland 64, and packing 65 in contact with fluid 
17. 
The mechanism is drivenly rotated through drive means 13. Drive means 13 is 
shown as an external spline. Drive means such as internal splines, shaft 
and key or other conventional structure may be used. 
The pressure sensitive control 52, shown in dashed lines as an option 
attached to valve means 31 may be used to actuate the valve means 31 
controlling the flow of fluid to position the movable weight and regulate 
the generated centrifugal force. The valve can be set up without the 
pressure sensitive control to be operated manually or remotely through 
cable, electrical or fluid control means depending upon the various 
application circumstances. 
The pressure source 32 is one of various types common in the art that 
supplies pressurized fluid as required to force the weight to a less 
eccentric position. 
FIGS. 11, 12 and 13 show another embodiment. The mechanism has pressure 
source, control means, pressure gauge and circuit as described previously 
in the foregoing embodiment descriptions. The bearing journal passage and 
conduit to the piston side of the cylinder are not shown. The breather in 
the piston rod end of the cylinder is understood but not shown. 
In the mechanism 90 dual pivoting weights 85 are pivotally connected by 
pins 86 to shaft body 12. The pivot pins are located generally 
perpendicular to the axis of rotation. The weights are clevis shaped and 
pin connected by pins 92 to push-pull rods 87. These push-pull rods being 
connected at a common joint with the boss of the extended piston rod 62. 
The three pieces are commonly connected by pin 89. The weights pivot as 
the piston rod moves in and out. 
Broken lines show the outline of one of the weights, some of the linkage 
and piston rod in the zero eccentricity mode wherein the mechanism is 
essentially balanced. 
The cylinder 11 is fixedly mounted to the shaft body 12 by means of flange 
88. The cylinder piston rod extends and retracts radially, generally 
perpendicular to the axis of rotation. 
It will be recognized by those skilled in the art that the cylinder shown 
or other types of cylinders could be mounted in a variety of attitudes 
using different mounting techniques without departing from the spirit of 
the invention. 
The weights, rods, pins, piston rod, seals, (not shown) piston, (not shown) 
make up the compound eccentric weight. When these parts are situated in 
the zero eccentricity mode indicated by the broken lines as noted they 
tend to move to an eccentric position shown clearly in FIG. 11. Their 
position and the generated centrifugal force is regulated as previously 
discussed. 
It is noted that all of the centrifugal force generated as the mechanism is 
rotated is not transmitted through fluid pressure in the cylinder to the 
shaft body. The majority of the force is transmitted to the shaft body 
through weight-shaft pivot pins 86. It is one of the objectives of this 
embodiment to provide a mechanism with large capacity with a relative low 
fluid pressure. As in the other embodiments; the weight, shape and 
geometry of the movable parts is known. The pressure in the cylinder can 
be directly related to the total centrifugal force. Centrifugal force 
calculations are made for multiple positions of the compound eccentric 
weight. Interpolation is used to know the force values for the infinite 
number of positions available. 
Control means 52, an optional device, is shown in dashed lines, as a part 
of and adapted to valve means 31. This control means is pressure sensitive 
to the pressure in the cylinder through the connecting circuit. The 
control operates the valve means to allow flow in or out of the cylinder. 
This flow maintains or limits the pressure in the circuit by positioning 
the movable weight. The control is readily adjustable either manually or 
by remote control means. 
The pressure source 32 is one of various types common in the art that 
supplies pressurized fluid as required to force the weight to a less 
eccentric position. 
FIG. 14, 15 and 16 show another embodiment. The mechanism has a pressure 
source, control means, pressure gauge and circuit as described previously 
in the foregoing embodiment descriptions. The bearing journal passage and 
conduit to the piston rod side of the cylinder are not shown. The breather 
in the piston end of the cylinder is understood but not shown. 
The mechanism is drivenly rotated through drive means 13. Drive means 13 is 
shown as an external spline. Drive means such as internal splines, shaft 
and key or other conventional structure may be used. 
In the mechanism 100 the pivoting weight 93 is pin connected to hinges 94 
of the shaft body 12 by pins 95. Pins 95 are located generally parallel to 
the axis of rotation. The weight 93 is shown in all three figures in its 
zero eccentricity mode wherein the mechanism is essentially balanced. 
The cylinder 11 is shown pivotly mounted to the shaft body hinge brackets 
96 by pin 97. The cylinder piston rod 62 is pivotly connected to weight 
hinge brackets 98 by pin 99. As the flow of fluid to and from the piston 
rod side of the cylinder moves the piston rod in and out it controls the 
position of the weight 93. The breather for the cylinder is not shown. 
Broken lines outline an eccentric position of the pivoted weight in FIGS. 
15 and 16. 
The weight 93, pin 99, rod 62, piston (not shown) and seals (not shown) 
make up the compound eccentric weight. When these parts are situated in 
the zero eccentricity mode shown in FIGS. 15 and 16 and the mechanism is 
balanced they tend to move to an eccentric position typified by the broken 
line outline of the weight in FIGS. 15 and 16. The cylinder and rod pivot 
as the rod moves in and out describing a plane perpendicular to the axis 
of rotation. The position of the weights and the generated centrifugal 
force is regulated as previously discussed. 
It is noted that in this embodiment as in mechanism 90, that all of the 
centrifugal force generated is not transmitted through the fluid pressure 
to the shaft body and bearing journals. The hinges 94 transmit some force 
directly to the shaft body and thus to the bearing journals. As before 
with all things being known the pressure in the cylinder can be directly 
related to the total centrifugal force generated at any eccentric weight 
position and any vibratory speed. 
Control means 52, an optional device, is shown in dashed lines, as a part 
of and adapted to valve means 31. This control means is pressure sensitive 
to the pressure in the cylinder through the connecting circuit. The 
control operates the valve means to allow flow in or out of the cylinder. 
This flow maintains or limits the pressure in the circuit by positioning 
the movable weight. The control is readily adjustable either manually or 
by remote control means. 
The pressure source 32 is one of various types common in the art that 
supplies pressurized fluid as required to force the weight to a less 
eccentric position. 
The foregoing embodiments describe novel variable eccentric vibration 
generating mechanisms. An important advantage of the mechanisms is the 
ability to increase or decrease force without changing the vibrational 
speed. Vibration can be eliminated without stopping the shaft or changing 
the rotational speed. Other devices that can vary the force without 
changing the speed are available but they use liquids for the movable 
weight. The liquids are forced from one chamber to another by pneumatic 
and hydraulic means. The chambers and their arrangement are especially 
bulky. Specific reference is made to U.S. Pat. No. 3,616,730, Nov. 2, 
1971, by Boone, Fridley, and Bush (U.S. Cl. 94-50V). 
The variable eccentric mechanisms (VEMECH) can be built in a more compact 
package and at less cost. The size of the package is important because it 
adds to the versatility of the invention. It makes the invention adaptable 
in relatively restricted spaces. It is also available in elongated forms 
as required. In addition the more compact units have less inertia or 
flywheel effect and require less torque to start and stop and less 
horsepower to accelerate. The optional pressure sensitive control means is 
extremely valuable in selected applications. The most important feature of 
the invention is the ability to record the pressure caused by the rotating 
eccentric weight and relate this to the centrifugal force being generated. 
The knowledge of the value of centrifugal force will help in vibrational 
amplitude regulation and matching vibrational effort to the assigned work. 
The most productive force value can be repeated accurately without guess 
work or unnecessary delay. This visible record of the generated 
centrifugal force through conversion of the pressure recording is not 
available on any other device known to the inventor. Another advantage is 
the variety of pressure sources listed previously as hydraulic pumps, air 
compressors, hydraulic cylinder and grease gun that may be used as the 
application circumstance dictates. Other advantages of this invention will 
be obvious to those skilled in the art. 
Preferred embodiments of the invention have been illustrated in the 
accompanying Drawings and described in the foregoing Detailed Description 
and Summary. It will be understood that the invention is not limited to 
the embodiments shown and described.