U.S. patent application number 16/344790 was filed with the patent office on 2020-02-13 for feeder.
This patent application is currently assigned to REC Silicon Inc. The applicant listed for this patent is REC Silicon Inc. Invention is credited to Robert J. Geertsen.
Application Number | 20200048007 16/344790 |
Document ID | / |
Family ID | 61971792 |
Filed Date | 2020-02-13 |
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United States Patent
Application |
20200048007 |
Kind Code |
A1 |
Geertsen; Robert J. |
February 13, 2020 |
FEEDER
Abstract
A feeder operable to convey a divided solids material comprises
a conduit and an actuator. The conduit has a hollow body with a
length, a first end, a second end opposite the first end and a
displaceable body segment defined along at least a portion of the
length. The displaceable body segment has at least a first fixable
location positionable at a first fixed location. The actuator is
positioned to apply force to the conduit and is controllable to
cause selected flow of divided solids material in a feed direction
extending generally from the first end to the second end. Methods
are also disclosed.
Inventors: |
Geertsen; Robert J.;
(Eltopia, WA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
REC Silicon Inc |
Moses Lake |
WA |
US |
|
|
Assignee: |
REC Silicon Inc
Moses Lake
WA
|
Family ID: |
61971792 |
Appl. No.: |
16/344790 |
Filed: |
October 19, 2017 |
PCT Filed: |
October 19, 2017 |
PCT NO: |
PCT/US2017/057448 |
371 Date: |
April 24, 2019 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
15333652 |
Oct 25, 2016 |
10040637 |
|
|
16344790 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B65G 25/02 20130101;
B65G 65/489 20130101; B65G 2201/042 20130101; B65G 2812/0384
20130101 |
International
Class: |
B65G 25/02 20060101
B65G025/02; B65G 65/48 20060101 B65G065/48 |
Claims
1. A feeder operable to convey a divided solids material,
comprising: a conduit having a hollow body with a length, a first
end, a second end opposite the first end and a displaceable body
segment defined along at least a portion of the length; the
displaceable body segment having at least a first fixable location
positionable at a first fixed location; an actuator positioned to
apply force to the conduit and controllable to displace the
displaceable body segment to cause selected flow of divided solids
material within the conduit in a feed direction extending generally
from the first end to the second end.
2. The feeder of claim 1, wherein the actuator is supported by the
conduit and moves with the displaceable body segment during a
feeding operation.
3. The feeder of claim 2, wherein the actuator comprises a rotating
offset mass, and wherein the rotating offset mass is operated to
generate oscillating motion of the displaceable body segment and
the attached actuator.
4. The feeder of claim 2, wherein the displaceable body segment is
cyclically displaced through a closed trajectory having at least
one of a vertical component and a horizontal component.
5. The feeder of claim 2, wherein the displaceable body segment has
a second fixable location downstream of the first fixable location
in the feeding direction and positionable at a second fixed
location.
6. The feeder of claim 1, wherein the displaceable body segment has
a curved profile, wherein the curved profile has a length longer
than a shortest distance separating the first fixable location and
a second fixable location, and wherein the actuator is attached to
the displaceable body segment approximately at an inflection point
for a curve of the curved profile.
7. The feeder of claim 1, wherein the actuator is positioned
stationarily and has a controllably movable element that contacts
the displaceable body segment.
8. (canceled)
9. The feeder of claim 1, Wherein the actuator is an elongate
member having a distal end pivotable into contact with the
displaceable body segment to selectively move the displaceable body
segment and a proximal end pivotably connected to a pivot
point.
10. The feeder of claim 1, wherein the displaceable body segment
comprises an intermediate section configured to collect a portion
of the divided solids material when the displaceable body segment
is at rest.
11. The feeder of claim 10, wherein the intermediate section is
configured to collect a leading edge of a flow of divided solids
material received from the first end of the feeder.
12. The feeder of claim 1, wherein the displaceable body segment
comprises an intermediate section configured for positioning at a
slight angle relative to horizontal, a first upright section
positioned upstream of the intermediate section and a second
upright section positioned downstream of the intermediate
section.
13. (canceled)
14. (canceled)
15. A feeder, comprising: a conduit having an inlet end, an outlet
end opposite the inlet end and a displaceable body segment defined
along a feeding direction between the inlet end and the outlet end;
the inlet end being configured for connection to a source of
material to be fed by the feeder; the outlet end being configured
to convey divided solids material from the feeder to a location
downstream of the feeder, wherein the outlet end is configured for
positioning at a lower height than the inlet end; the displaceable
body segment being sized to have a length longer than a shortest
distance between the inlet end and the outlet end and to define a
curved profile with at least one inflection point when installed;
the displaceable body segment when installed defining an
intermediate section configured to support accumulated divided
solids material therein at an angle of repose of the material, and
to reduce movement of material in the feeding direction when the
displaceable body segment is at rest; and an actuator connected to
the displaceable body segment to controllably displace the
displaceable body segment during a feeding operation.
16. (canceled)
17. (canceled)
18. (canceled)
19. The feeder of claim 15, wherein the intermediate section is
caused to be displaced from a substantially lateral position at
which no flow occurs to a downwardly tilted position at which flow
towards the outlet end occurs.
20. The feeder of claim 15, wherein the actuator is configured to
move at a rate sufficient to cause displacement of the displaceable
body section such that the solids material moves at a selected rate
between a low trickle flow and a high bulk filling flow.
21. A method of conveying a divided solids material with a feeder,
comprising: using a sensor to monitor an amount of the divided
solids material being conveyed with the feeder; receiving signals
from the sensor at a controller; sending control signals from the
controller to the feeder to control a flow rate of the divided
solids material over a flow rate range ratio of greater than 1:50
of a low flow rate to a high flow rate.
22. The method of claim 21, wherein using a sensor to monitor an
amount of the solid material being conveyed comprises configuring
the sensor to measure a loss of weight of the solid material from a
source of the material positioned upstream of the feeder.
23. The method of claim 21, wherein using a sensor to monitor an
amount of the solid material being conveyed comprises configuring
the sensor to measure a gain in weight from the solid material
conveyed to a receptacle positioned downstream of the feeder.
24. The method of claim 21, wherein the feeder comprises a conduit
segment for receiving the solid material and that is displaceable
according to the control signals from the controller to achieve a
desired flow rate of the material from the feeder.
25. The method of claim 21, wherein the flow rate range ratio is
greater than 1:4000.
26. A method of conveying divided polysilicon, comprising:
receiving divided polysilicon from a source into a conduit of a
feeder; controllably moving the conduit through an operation path
in which the conduit is positioned in at least a first position at
which flow through the conduit occurs and a second position at
which flow through the conduit is stopped; and receiving the
divided silicon material flowing through the conduit, when the
conduit is positioned at least in a first position, in a receptacle
positioned downstream of an outlet end of the conduit.
Description
BACKGROUND
[0001] Silicon of ultra-high purity is used extensively in the
electronics and photovoltaic industries. High purity granular
polysilicon materials with only trace of amounts of contamination
measured at the part per billion levels are often required.
Producing such materials is possible, but then extreme care must be
taken in any handling, packaging or transportation operations to
avoid subsequent contamination.
[0002] Conventional feeding and flow control technologies used to
convey granular polysilicon materials includes components having
metal in their construction (e.g., valves, conduits, etc.). When
protective coatings or linings are compromised, or when wear occurs
at the interfaces of moving parts, for example, contamination from
metal parts can occur, which is unacceptable.
[0003] Valves used to regulate the flow of granular materials that
rely on components that move relative to the material being
conveyed, such as butterfly dampers, pinch bladders, diaphragms,
gates, etc., have a disadvantage of potentially crushing granules
of the material, which can both reduce its value and potentially
damage the components and other equipment.
[0004] In addition, conventional feeders may not provide sufficient
control over the rate of flow granular polysilicon and/or the flow
rate range. Conventional vibrating tray feeders may achieve a feed
rate range between a lowest controllable feed rate and a highest
controllable feed rate of only about 1:50, but a much higher feed
rate range is desirable. Other conventional approaches allow higher
feed rate ranges to be achieved, but only with apparatus having
multiple parts within the control volume of the flowing material
that must move relative to each other, such as auger screws, rotary
vanes and other similar structures. Multiple parts in relative
motion within the control volume, however, leads to a greater risk
of contamination.
[0005] Also, such conventional feeders are difficult to purge with
a suitable process gas and/or clean in part because of their
complicated constructions. The multi-piece constructions typically
require an extensive use of seals to prevent leakage through
components that move relative to each other.
[0006] Conventional vibratory solids conveyors typically have a
rigid container constrained by linkages and/or springs that can be
driven by an eccentric weight assembly coupled to an electric motor
or an electromagnetic drive in a desired motion, such as elliptical
rotation that includes horizontal and vertical components.
[0007] Conventional approaches to conveying solids, including
vibratory conveyors, screw augers, belt conveyors and other similar
devices, are not capable of achieving high performance over a large
range of flows while ensuring that ultrahigh purity is
maintained.
SUMMARY
[0008] Described below are apparatus and methods that address some
of the drawbacks in conventional approaches to feeding solids
materials, including granular polysilicon.
[0009] According to a first implementation, a feeder operable to
convey a divided solids material comprises a conduit and an
actuator. The conduit has a hollow body with a length, a first end,
a second end opposite the first end and a displaceable body segment
defined along at least a portion of the length. The displaceable
body segment has at least a first fixable location positionable at
a first fixed location. The actuator is positioned to apply force
to the conduit and controllable to cause selected flow of divided
solids material in a feed direction extending generally from the
first end to the second end.
[0010] In some implementations, the actuator is supported by the
conduit and moves with the displaceable body segment during a
feeding operation. The actuator can comprise a rotating offset
mass, and the rotating offset mass can be operated to generate
oscillating motion of the displaceable body segment and the
attached actuator. The displaceable body segment can be cyclically
displaced through a closed trajectory having at least one of a
vertical component and a horizontal component.
[0011] In some implementations, the displaceable body segment has a
second fixable location downstream of the first fixable location in
the feeding direction and positionable at a second fixed
location.
[0012] In some implementations, the displaceable body segment has a
curved profile with a length longer than a shortest distance
separating the first fixable location and the second end, and the
actuator is attached to the displaceable body segment approximately
at an inflection point for a curve of the curved profile.
[0013] In some implementations, the actuator is positioned
stationarily and has a controllably movable element that contacts
the displaceable body segment. In some implementations, the
actuator comprises a linear actuator. In some implementations, the
actuator comprises an elongate member having a distal end pivotable
into contact with the displaceable body segment to selectively move
the displaceable body segment and a proximal end pivotably
connected to a pivot point.
[0014] In some implementations, the displaceable body segment
comprises an intermediate section configured to collect a portion
of the divided solids material when the displaceable body segment
is at rest. The intermediate section can be configured to collect a
leading edge of a flow of divided solids material received from the
first end of the feeder.
[0015] In some implementations, the intermediate section is
configured for positioning at a slight angle relative to
horizontal, and there is a first upright section positioned
upstream of the intermediate section and a second upright section
positioned downstream of the intermediate section.
[0016] In some implementations, the conduit is made from a
resilient material. In some implementations, the conduit comprises
polyurethane hose material.
[0017] In some implementations, a feeder comprises a conduit and an
actuator. The conduit has an inlet end, an outlet end opposite the
inlet end and a displaceable body segment along a feeding direction
between the inlet end and the outlet end. The inlet end is
configured for connection to a source of material to be fed by the
feeder. The outlet end is configured to convey divided solids
material from the feeder to a location downstream of the feeder.
The outlet end is positioning at a lower height than the inlet end.
The displaceable body segment is sized to have a length longer than
a shortest distance between the inlet end and the outlet end and to
define a curved profile with at least one inflection point when
installed. When installed, the displaceable body segment defines an
intermediate section configured to support accumulated material
therein at an angle of repose of the material, and to reduce
movement of material in the feeding direction when the displaceable
body segment is at rest. The actuator is connected to the
displaceable body segment to controllably displace the displaceable
body segment in a feeding operation.
[0018] In some implementations, the actuator is controllable to
displace the displaceable body segment in an oscillating cycle. In
some implementations, the actuator is manually operable. In some
implementations, the displaceable body segment extends
substantially from the inlet end and substantially to the outlet
end.
[0019] In some implementations, the intermediate section is caused
to be displaced from a substantially lateral position at which no
flow occurs to a downwardly tilted position at which flow towards
the outlet end occurs.
[0020] In some implementations, the actuator can be configured to
move at a rate sufficient to cause displacement of the displaceable
body section such that the solids material moves at a selected rate
between a low trickle flow and a high bulk filling flow.
[0021] According to a method implementation, a method of conveying
a divided solids material with a feeder comprises using a sensor to
monitor an amount of the divided solids material being conveyed
with the feeder, receiving signals from the sensor at a controller
and sending control signals from the controller to the feeder to
control a flow rate of the divided solids material over a flow rate
range ratio of greater than 1:50 of a low flow rate to a high flow
rate.
[0022] According to some implementations, using a sensor to monitor
an amount of the solid material being conveyed can comprise
configuring the sensor to measure a loss of weight of the solid
material from a source of the material positioned upstream of the
feeder. According to some implementations, using a sensor to
monitor an amount of the solid material being conveyed comprises
configuring the sensor to measure a gain in weight from the solid
material conveyed to a receptacle positioned downstream of the
feeder.
[0023] According to some implementations, the feeder can comprise a
conduit segment for receiving the solid material and that is
displaceable according to the control signals from the controller
to achieve a desired flow rate of the material from the feeder. In
some implementations, the flow rate range ratio is greater than
1:4000.
[0024] According to another method implementation, a method of
conveying divided polysilicon comprises receiving divided
polysilicon from a source into a conduit of a feeder, controllably
moving the conduit through an operation path in which the conduit
is positioned in at least a first position at which flow through
the conduit occurs and a second position at which flow through the
conduit is stopped, and receiving the divided silicon material
flowing through the conduit, when the conduit is positioned at
least in a first position, in a receptacle positioned downstream of
an outlet end of the conduit.
[0025] Desirably, the feeding and flow control technologies
described herein tend not to rely on reducing the cross section of
the conduit, which reduces damage to the material being conveyed
and the equipment.
[0026] The foregoing and other objects, features, and advantages
will become more apparent from the following detailed description,
which proceeds with reference to the accompanying figures.
BRIEF DESCRIPTION OF THE DRAWINGS
[0027] FIG. 1 is side elevation view of a representative
implementation of a feeder in its at rest position.
[0028] FIGS. 2-13 are side elevation views of the feeder of FIG. 1
schematically showing the feeder of FIG. 1 and material being fed
with the feeder in different positions throughout several cycles of
motion.
[0029] FIG. 14 is a graph showing the trajectory of the motor and a
segment of the body of the feeder through a cycle with reference to
the positions shown in FIGS. 2-13.
[0030] FIG. 15 is a graph of feed rate for the feeder vs motor
speed.
[0031] FIG. 16 is a table of data used to plot the graph of FIG.
15.
[0032] FIGS. 17-18 are side elevation views of another
implementation of the feeder in which the actuator for moving the
body is a double acting pneumatic cylinder.
[0033] FIG. 19 is a schematic block diagram of a representative
control circuit for regulating operation of the feeder as a
gravimetric feeder according to control based on a loss of
weight.
[0034] FIG. 20 is a schematic block diagram of a representative
control circuit for regulating operation of the feeder as a
gravimetric feeder according to control based on a gain in
weight.
[0035] FIG. 21 is a schematic block diagram of a representative
control circuit for regulating operation of the feeder as a
volumetric feeder.
[0036] FIG. 22 is a side elevation view of another implementation
of the feeder in which a vacuum or suction device has been added to
assist in controlling dust during feeding operations.
[0037] FIG. 23A is a side elevation view of another implementation
of the feeder in which an intermediate section is constrained to
control flow as desired.
[0038] FIG. 23B is an enlarged section view of a portion of the
feeder of FIG. 23A showing solids in the feeder at rest when the
feeder is in a zero flow position.
[0039] FIG. 24A is a side elevation view of the feeder of FIG. 23A
showing the feeder in a different position.
[0040] FIG. 24B is an enlarged section view of a portion of the
feeder of FIG. 24A showing solids in the feeder beginning to
flow.
[0041] FIG. 25A is a side elevation view of the feeder of FIG. 23A
showing the feeder in another different position.
[0042] FIG. 25B is an enlarged section view of a portion of the
feeder of FIG. 25B showing solids in the feeder and the feeder
positioned for maximum flow.
[0043] FIGS. 26A and 26B are side elevation views showing
variations of the feeder of FIG. 23A having members of different
lengths.
[0044] FIGS. 27A and 27B are side elevation views of the feeder of
FIG. 23A showing another variation in the member.
DETAILED DESCRIPTION
[0045] Referring to FIG. 1, a side elevation view of a
representative implementation of a feeder 100 through which
material can be fed is shown. The feeder 100 has a body 102 that is
generally tubular, which is also sometimes referred to herein as a
conduit. Because the body 102 is tubular, it has a hollow cross
section. The cross section of the body 102 may define an inner
surface that is circular, elliptical, rounded or even multi-sided.
The outer surface may have any suitable shape, and the wall(s)
between the inner surface and outer surface may have any suitable
thickness (constant or variable).
[0046] The body 102 has a first end 104 and an opposite second end
106. Between the first and second ends 104, 106, there is a
displaceable body segment 108 that can be caused to displace or
move, or to vibrate or oscillate (and in some cases, to do so
cyclically), as described below in greater detail, to cause
material to be conveyed or fed from the first end 104, through the
body 102 and to the second end 106. The body 102 is formed of one
or more materials and to have selected dimensions such that it can
be moved between different positions as desired, which is described
below in more detail.
[0047] In some implementations, the material to be fed or conveyed
is one or more solids materials comprising particles, such as a
divided solids material. Polysilicon is one example of a material
that can be provided as a divided solids or finely divided solids
material. Other materials can also be fed using the described
apparatus and methods. Also, the material to be fed can be a
mixture of two or more different component materials.
[0048] A material is defined to be flowable if the bulk stress
acting on the material exceeds the material's bulk strength. In the
case of a granular material, one measurement used to indicate a
material's ability to flow is the angle of repose of the material.
The angle of repose of a granular material is the steepest angle of
descent or dip relative to the horizontal plane to which the
material can be piled without slumping (at this angle, the material
on the slope face is on the verge of sliding). A material that has
a lower tendency to flow may be comprised of particles with a
relatively high degree of inter-particle friction, such as
particles of a material having more angular shapes that tend to
interlock with each other. In the same way, flowability of a
material tends to be decreased if there is plastic deformation of
particles, partial melting of particles, moisture present in and/or
around particles and/or another factor tending to increase adhesion
between particles.
[0049] In some cases, when particles of a material are at rest and
not flowing, e.g., because the angle of repose for the material has
not been exceeded, the particles can nevertheless be induced to
flow by disturbing them, such as through applying energy to them,
e.g., in the form of vibrations.
[0050] In the case of granular polysilicon (also sometimes referred
to herein as granulate polysilicon and granules), the polysilicon
particles are generally spheroids having an average diameter of
0.25 to 20 mm, such as an average diameter of 0.25-10 mm, 0.25-5
mm, or 0.25 to 3.5 mm. As used herein, "average diameter" means the
mathematical average diameter of a plurality of granules.
Individual granules may have a diameter ranging from 0.1-30 mm,
such as 0.1-20 mm, 0.1-10 mm, 0.1-5 mm, 0.1-3 mm or 0.2-4 mm. The
individual particles of any given material may have generally the
same size and shape, or they vary in size and shape.
[0051] The open cross section of the tubular body 102 or conduit
can sized to be at least 2-3 times greater than the major dimension
of the largest target particle size such that flow of particles of
such size through the feeder is facilitated. In specific examples,
the major dimension is a diameter that is 2-3 times, 5 times, 10
times or 100 times the diameter of the largest target particle size
of the material to be conveyed.
[0052] The first end 104 can be connected to an upstream source of
material to be fed, such as a material comprising solids. In the
illustrated implementation, the first end 104 is connected to the
outlet end of a hopper H, which is stationary. Instead of the
hopper H, the feeder 100 can be connected downstream of any other
component or conduit that supplies material to be fed. The second
end 106 can be connected to an outlet from which material fed by
the feeder 100 is discharged as shown, or to any other downstream
location. As shown in FIG. 13, for example, the second end 106 can
convey material to a receptacle R.
[0053] The displaceable body segment 108 can have a first fixable
location 110, e.g., a location that is positionable at a first
fixed location. Similarly, the displaceable body segment 108 can
have a second fixable location 112, e.g., a second location that is
fixable at a second fixed location. The first and second fixable
locations 110, 112 define the approximate ends of the displaceable
body segment 108. In the illustrated implementation, the first
fixable location 110 is located in the area of the first end 104,
and second fixable location 112 is located in the area of the
second end 106. In other implementations, the first and second
fixable locations 110, 112 can be located at points spaced from the
first and second ends 104, 106, respectively, to define
displaceable body segments of different lengths and
characteristics.
[0054] Typically, at least the displaceable body segment 108 is
configured to be sufficiently flexible to be displaced as desired,
such as by selecting appropriate material(s) and their dimensions.
As one example, in the illustrated implementation, the body 102,
including the displaceable body segment 108, is formed of a section
of flexible polyurethane hose or conduit having an appropriate
uniform diameter and wall thickness. In other implementations, one
or more different materials may be used for the body 102 and/or
displaceable body segment 108, and/or non-uniform wall thicknesses
and/or diameters may be used.
[0055] As shown in the implementation of FIG. 1, there are no
moving parts within the displaceable body segment 108, i.e., there
are no moving parts within the internal volume defined by the
displaceable body segment 108, which can be designated as part of
the control volume for the feeder. This is advantageous because
contact between solid material flowing through the displaceable
body segment 108 and any moving parts or other sensitive areas
causes wear and other problems, particularly with solid material
such as granular polysilicon.
[0056] As also shown in FIG. 1, the feeder 100 has an actuator,
e.g., a motor 130 or other device configured to move the body 102,
and in particular the displaceable body segment 108, to cause it to
selectively oscillate or otherwise move, typically in a cyclical
fashion. The motor 130 is positioned to impart motion to the
displaceable segment 108, such as by being mounted to the body 102
as shown (or having a component that contacts the body). The motor
130 can be an electric motor having an eccentric weight. As stated,
any other type of actuator or other device sufficient to impart the
desired motion to the displaceable body segment 108 could also be
used, such as a pneumatic cylinder, a hydraulic cylinder, or a
mechanical drive such as a rack and pinion assembly powered by a
servo motor, as a few examples.
[0057] Referring to FIG. 1, the body 102 has an S-shaped profile in
elevation. In the vertical direction, the first end 104 is
positioned at a level above the second end 106. In the horizontal
direction, the first and second ends 104, 106 are offset from each
other. The S-shaped profile of the body 102 has two curves bending
in opposite directions in a single plane that meet at inflection
point within the displaceable body segment 108. Other
configurations can also be used, depending on the particular
operating requirements for the application. In the illustrated
implementation, the motor 130 is positioned to have its rotational
axis substantially perpendicular to the displaceable body segment
108.
[0058] Referring again to FIG. 1, the body 102 is shown as a
transparent component to allow its interior and the material M to
be illustrated. The feeder 100 is shown partially filled with
material M that has come to rest at an intermediate point within
the body 102. A leading edge or head portion of the material M,
which is inclined from left to right in FIG. 1, in inclined at the
material's angle of repose A. In the illustrated implementation,
e.g., the angle of repose for the material M, such as granular
polysilicon material, is approximate 31.degree.. The section of the
body 102 in FIG. 1 where the material M is at rest can be described
as an intermediate section (also sometimes referred to as a repose
section). The intermediate section can be approximately level in
the downstream direction as shown (i.e., from right to left in FIG.
1), angled upwardly or angled downwardly, together with any
necessary change to the section's length to ensure that sufficient
run out is provided, to assist in ensuring that no flow occurs when
the feeder 100 is not operating. The segments adjacent the first
and second ends 104, 106 can be relatively upright as shown to have
the material flowing into and out of the body 102 assisted by
gravity to a maximum degree, but other configurations are also
possible.
[0059] By displacing or moving the displaceable body segment 108 as
described in more detail below, the material M can be moved or feed
through the body 102 along a feed path as indicated generally by
the arrows F (see, e.g., FIGS. 2, 5, 6, 9-13) and out through the
second end 106 to a subsequent component and/or location.
[0060] The steady state cyclical motion of the feeder 100 in a
representative operating scenario is shown in FIGS. 2-13.
Specifically, FIGS. 2-13 are additional side elevation views of the
feeder 100 showing how operation of the motor 130 causes
oscillatory motion of the displaceable body segment 108. Referring
to FIG. 2, during steady state operation of the motor 130 at a
speed of 225 RPM in the counterclockwise direction, the position of
the motor 130 has moved to the right and down. Specifically, at a
time of 0.07 seconds relative to an arbitrary starting point on the
motor's steady state trajectory, the motor 130 has moved 2.7 cm to
the right (Delta X=+2.7 cm) and 2.3 cm down (Delta Y=-2.3 cm).
Because the motor 130 is attached to the displaceable body segment
108, the displaceable body segment has substantially the same
motion as the motor 130.
[0061] As the displaceable body segment 108 moves down to the
right, the material M, and specifically, the granules that make up
the material M, have a relative velocity that is in a direction up
to the left, thereby creating a void V in the material M as shown
schematically in FIG. 2. The growing void V is not constrained by
the material's angle of repose, and so material will begin to flow
from right to left, beginning in the intermediate section along the
flow path F. As flow of material continues, the void V will be
filled, and additional material from the hopper H will enter the
body 102 to replace the material flowing away from the intermediate
section. It can be said that the material being fed is entrained in
pockets and sequentially moved throughout the feeding process. A
profile or trajectory P of the cyclical motion of the motor
130/displaceable body segment 108, which is described below in
greater detail in connection with FIG. 14, is shown superimposed on
the rotational axis of motor 130 in FIGS. 2-13.
[0062] Subsequently, as shown in FIG. 3, while the motor speed is
maintained at 225 RPM and at 0.14 seconds, the displaceable body
segment 108 and the material M are accelerated up to the left. The
void V is collapsed, and the material M is once again constrained
by its angle of repose, but at position farther along the flow path
F. Flow from the hopper H is stopped. At the point shown in FIG. 3,
the motor 130/displaceable body segment 108 have moved 4.5 cm to
the left (Delta X=-4.5 centimeters), and 2.4 cm up (Delta Y=2.4 cm)
from the position shown in FIG. 2.
[0063] In FIG. 4, at 0.20 seconds, the displaceable body segment
108 reaches its left most position, stops and starts to move down
to the right again. The material M maintains its velocity in a
direction up to the left. Relative flow between the hopper H and
body 102 remains stopped. At this point, Delta X=-2.3 cm and Delta
Y=1.8 cm relative to the position shown in FIG. 3.
[0064] In FIG. 5, at 0.27 seconds, the inertia of the material M
causes continued motion up to the left with the displaceable body
segment 108 moving down to the right. At this point, the relative
velocity is at its maximum. The flow at the head portion of the
material along with the displaceable body segment 108 moving down
to the right produces a more rapidly growing void V. Because the
material M is not constrained by its angle of repose, flow of
material starts to fill the void V. Flow from the hopper H resumes
to replace material flowing below. At this point, Delta X=4.2 cm
and Delta Y=-1.8 cm relative to the position shown in FIG. 4.
[0065] In FIG. 6, at 0.34 seconds, the inertia of the material M
allows continued motion up to the left at the head portion of the
material. With the material continuing to flow, along with movement
of the displaceable body segment 108 down to the right, voiding
continues to take place. Because the material is not constrained by
its angle of repose, flow continues to fill the void. Flow from the
hopper H continues to replace material flowing below. At this
point, Delta X=2.7 cm and Delta Y=-2.3 cm relative to the position
shown in FIG. 5.
[0066] In FIG. 7, at 0.41 seconds, the head of the material M can
be seen advancing along the flow path F. The displaceable body
segment 108 and material M are accelerated up to the left. The void
V has collapsed, and granular material is once again constrained by
its angle of repose. Relative flow between this granular material
and the downstream section of the displaceable body segment 108 has
stopped. Flow from the hopper H has stopped. At this point, Delta
X=-4.5 cm and Delta Y=2.4 cm relative to the position shown in FIG.
6.
[0067] In FIG. 8, at 0.47 seconds, the material M is advancing
farther along the flow path F. The displaceable body segment 108
has reached its upper left most position. It will then stop, and
start to move down to the right. The inertia of the material M
remains in a direction up to the left. Relative flow in the
downstream direction in the displaceable body segment 108 has
stopped. Flow from the hopper H has stopped. At this point, Delta
X=-2.3 cm and Delta Y=1.8 cm relative to the position shown in FIG.
7.
[0068] In FIG. 9, at 0.54 seconds, the displaceable body segment
108 is moving down to the right and has reached its maximum
velocity. The flow in the displaceable body segment 108 produces a
more rapidly growing void V. Because the material is not
constrained by its angle of repose, material starts to fill the
void. Flow from the hopper H resumes to replace material flowing
below. At this point, Delta X=4.2 cm and Delta Y=-1.8 cm relative
to the position shown in FIG. 8, i.e., the same position as is
shown in FIG. 5. Thus, one cycle is depicted in the sequence from
FIG. 5 through FIG. 9.
[0069] In FIG. 10, at 0.61 seconds, the inertia of the material M
allows continued motion up to the left along the displaceable body
segment 108 and into a discharge segment of the body 102. The
discharge segment can be positioned substantially upright as shown.
With the material continuing to flow along the flow path, along
with movement of the displaceable body segment down to the right,
voiding continues to take place. Because material is not
constrained by its angle of repose, flow continues to fill the
void. Flow from the hopper H continues to replace material flowing
below. At this point, Delta X=2.7 cm and Delta Y=-2.3 cm relative
to the position shown in FIG. 9.
[0070] In FIG. 11, 0.68 seconds, the head portion of the flow of
material along the flow path begins to fall from above through the
discharge section toward the second end 106. Material is also
advancing elsewhere along the flow path. The displaceable body
segment 108 and the material M are accelerated up to the left. The
void has collapsed, and material is once again constrained by it
angle of repose. Flow between the intermediate section and points
downstream has stopped. Also, flow from the hopper H has stopped.
At this point, Delta X=-4.5 cm and Delta Y=2.4 cm relative to the
position shown in FIG. 10.
[0071] In FIG. 12, at 0.74 seconds, material at the head portion of
the flow continues to fall toward the end 106. Material is also
advancing through intermediate points along the flow path. The
displaceable body segment 108 has reached the upper left most
position, stopped and started to move down to the right again. The
material M has maintained its velocity up to the left. Flow between
the angle of intermediate section and downstream segments has
stopped. Flow from the hopper has stopped. At this point, Delta
X=-2.3 cm and Delta Y=1.8 cm relative to the position shown in FIG.
11.
[0072] In FIG. 13, at 0.81 seconds, material at the head portion of
the flow, continues to fall as accelerated by gravity through the
second end 106 and is discharged from the feeder 100. Material is
advancing through the displaceable body segment 108 with the
displaceable body segment 108 moving down to the right. The
relative velocity of the displaceable body segment 108 is at its
maximum. The flow in the intermediate section causes a void V to
grow. Because the material is not constrained by its angle of
repose, flow starts to fill the void. Flow from the hopper H
resumes to replace material flowing below. At this point, Delta
X=4.2 cm and Delta Y=-1.8 cm relative to the position shown in FIG.
12.
[0073] As described above, FIG. 14 is a graph of X axis and Y axis
motion of the motor 130 and the displaceable body segment 108
showing their trajectory P and including references to show how the
positions of FIGS. 2-13 correlate to points on the trajectory.
Although FIGS. 2-13 show specific times for convenience of
illustration, the motion throughout the cycle continues smoothly
between discrete points as indicated by the trajectory P. Although
not specifically shown in the figures, there would typically be a
smooth ramping up of speed to the desired operating speed (e.g.,
225 rpm).
[0074] By maintaining the motion of the displaceable body segment
108 predominately in the XY plane, feeding efficiency is maximized,
and potential drawbacks from motion with components in the Z
direction (i.e., perpendicular to the page), which could introduce
torsional vibrations adverse to feeding, can be avoided. Thus, the
motor 130 (as well as the cylinder 230 described below) can be
positioned such that the forces they produce act predominately in
the XY plane. For the motor 130, the mounting can also be
configured so that the swinging mass does not introduce torsional
vibration effects that would tend to counteract smooth feeding.
[0075] As described, the motion of the displaceable body segment
108, and the resulting performance of the feeder, is influenced by
a number of variables. One such variable is the direction in which
the motor is rotated relative to the shape or profile of the
displaceable body section 108, including whether the motor's
rotation tends constrict or relax the curved sections in the
displaceable body segment 108. Another variable concerns the
magnitude and direction of residual forces in the displaceable body
segment 108 tending to resist the action of the motor (e.g., due to
the stiffness of the hose material and/or its configuration).
Depending upon the particular needs for a specific situation, the
user may determine that one direction of rotation is preferred over
the other and/or that the displaceable body segment should be
configured to have selected characteristics.
[0076] FIG. 15 is a graph showing how feed rate through the feeder
100 for the material (in g/second, and plotted on a logarithmic
scale) increases as the rotational speed of the motor 130 (in Hz)
is increased. FIG. 16 is a table providing data points for the
graph of FIG. 15. Overall, the feeder 100 shows excellent results
with a predictably increasing feed rate as motor speed is
increased, and a wide usable range. Repeated tests have shown that
these results are reproducible and accurate.
[0077] At high speeds, the eccentric weight of the motor 130
provides both a high centrifugal force and a high frequency to
produce a high feed rate. Conversely, at low speeds, the eccentric
weight provides a low centrifugal force amplitude at a low
frequency. The motion of a representative feeder was studied using
video analysis. Feed rate data corresponding to the video analysis
was obtained by evaluating a mass vs. time relationship of the
feeder's discharge. The mass of the material collected from the
discharge was weighed in a container supported by a load cell (such
as, e.g., a Model RAP3 single point load cell provided by Loadstar
Sensors of Fremont, Calif.). Comparisons of this measured feed rate
data with a calculated feed rate based on modelling the feeder as a
positive displacement pump show excellent agreement.
[0078] By way of contrast to conventional vibratory feeders, the
feeder 100 operates in a different frequency-amplitude regime.
Referring again to FIG. 16, the feeder in a representative
embodiment operates over a frequency range of 1.08-3.75 Hz and has
a maximum amplitude of about 80 mm (at 100% speed, with the
intermediate section at an average incline of about 30 degrees from
horizontal). In contrast, a conventional electromagnetic driven
rigid tray feeder operates over a frequency range of 20-60 Hz and
an amplitude of 1-11 mm. Similarly, a conventional eccentric motor
driven rigid tray feeder operates over a frequency range of 15-30
Hz and an amplitude of 1-10 mm. Likewise, another conventional
mechanically driven rigid tray feeder operates over a frequency
range of 5-15 Hz and an amplitude of 3-15 mm. Thus, the feeder
operates over a much lower frequency range and reaches a much
greater amplitude.
[0079] The electric motor 130 may be configured to be controlled by
a variable frequency drive (VFD), either as a separate component or
provided integrally with the motor. Such a VFD-controlled motor
provides precise control over the speed of the motor, and thus
allows a desired flow rate to be achieved. As a result of the
frequency-amplitude control of the feeder, the feeder is capable of
a flow rate range of 1:4700, which is far greater than the flow
rate range of about 1:50 achievable with a conventional vibrating
tray feeder.
[0080] Because the feeder 100 can achieve flow rates ranging from a
trickle flow at very low motor speeds to very high flow rates at
high motor speeds, it can be operated in a variety of different
ways, which increases the flexibility of its use. As one example,
in operating the feeder to reach a target weight of material to be
output, the feeder can be operated at high speed for an initial
period and then at low speed for a subsequent period as the target
weight is approached. Thus, the feeder is very well suited for use
in a continuous process where flow control of material is required.
The feeder can be used as a gravimetric feeder in bulk filling
applications.
[0081] FIG. 19 is a schematic block diagram of a control system for
the feeder 100 configured as a gravimetric feeder. In gravimetric
feeding, material is fed into a process at a constant weight per
unit of time since weight is a variable that can be readily
captured by a weighing module. According to the loss in weight type
of gravimetric feeding of FIG. 19, the amount of material fed into
the process is weighed at a source of the material. Thus, there is
a source load cell 310 coupled to a container representing the
source of material (not shown, but generally located upstream of
the feeder 100) that is connected to a controller 320 to send
signals corresponding to the container's loss in mass during a
feeding operation. The controller 320 is connected to the feeder
actuator (i.e., the motor 130) or other moving mechanism to send
control signals to carry out controlled operation of the feeder 100
in reaching a desired target, e.g., conveying a desired mass of the
material, including through control of the flow rate of material.
Additional feedback control could also be used.
[0082] As also shown in FIG. 19, an optional logic circuit 330 with
a container sensor 332 and a container sensor circuit 334 can be
provided. If provided, the container sensor 332 can be configured
to monitor whether a receiving container, such as the receptacle R
in FIG. 13, is in place. The container sensor circuit 334 can be
configured to send a signal to the controller 320 to indicate that
a receiving container is in place (container ready=Y) and that a
feeding operation can be commenced.
[0083] FIG. 20 is similar to FIG. 19, but shows a schematic block
diagram for the feeder 100 configured as a gain in weight type
gravimetric feeder. According to the gain in weight type of
gravimetric feeding of FIG. 20, the amount of material fed into a
process is weighed at a receiving container. Thus, there is a load
cell or other equivalent sensor 312 coupled to the receiving
container (such as the receptacle R). The sensor 312 is connected
to the controller 320 to send signals indicating the receiving
container's gain in mass during a feeding operation. As above, the
controller 320 carries out a feeding algorithm and sends control
signals to the motor 130 or other mechanism. Also, the optional
logic circuit 330 can be implemented, if desired.
[0084] FIG. 21 is similar to FIGS. 19 and 20, but shows a schematic
block diagram for the feeder 100 configured as a volumetric feeder
instead of a gravimetric feeder. As indicated, the controller 320
is connected to send control signals to the motor 130 based on a
control algorithm based on stored data 322, such as speed (cycle)
volumetric flow data describing a relationship between operating
speed of the motor and flow rate. Also, the optional logic circuit
330 can be implemented, if desired.
[0085] Another implementation of the feeder can be described in
connection with FIGS. 23A-25B. Referring first to FIG. 23A, a
feeder 400 has the first end 104 of the body 102 at a first fixed
location 110 similar to the feeder 100, but has an elongate member
420 proximate to at least a segment of the body 102, generally
between its ends 104, 106. The member 420 is operable to apply a
force and/or torque to the segment of the body 102 (and thus can be
described as another form of "actuator"), as well as to constrain
the body 102 to move on a selected path. In most cases, the force
and/or torque produces at least some displacement in the body 102
along all points that are not fixed. Thus, the displaceable body
segment 108 of the body 102 in the feeder 400 can be defined as
extending from close to the first end 104 to close to the second
end 106 (if fixed) or to the second end (if free to move). In
certain implementations, there could be multiple displaceable body
segments.
[0086] The member 420 has a distal end 421 that is configured to
contact the body 102 within the displaceable body segment 108, and
an opposite proximal end 423. The proximal end 423 of the member
420 is pivotably supported to pivot about a pivot point 414. As is
described below in more detail, it is only the member 420 that is
connected at the pivot point 414, and not any part of the body 102.
Rather, the displaceable body segment 108 of the body 102 is
contacted by the distal end 421 of the member 420. In the
illustrated implementation, the displaceable body segment 108 is
contacted by a band clamp 422 that at least partially encircles it
and extends lengthwise from the distal end 421 proximally over a
length of the band clamp 422.
[0087] By moving the member 420, e.g., by pivoting the member 420
about the pivot point 414, the displaceable body segment 108 is
moved and more specifically, an intermediate section I thereof can
be rotated to a selected angle, such as to shut off feeding (zero
feed rate), to allow for feeding at a maximum rate and/or to allow
for feeding at rates between the zero feed rate and the maximum
feed rate. In some implementations, the member 420 extends along
the displaceable body segment over at least a portion of the length
of the member 420.
[0088] The pivoting operation can be accomplished in discrete
operations or as in cyclical operations. Further, the rotation of
the intermediate section I can be accomplished manually or as step
in an automatic feeding process. In the illustrated implementation,
the member 420 has a forked end (not shown) that straddles the body
102 and is pivotably supported at the pivot point 414.
[0089] The intermediate section I (which tends to move greater
distances that other sections of the displaceable body segment 108
during operation) is shown schematically in FIG. 23A to include the
section contacted by the band clamp 422, and adjacent sections
upstream and downstream thereof. Depending upon a variety of
factors, almost any point along the body 102 except the first end
104 (which is fixed) may undergo at least a small displacement
during pivoting and thus is considered part of the displaceable
body segment 108.
[0090] The geometry of the intermediate section I, including its
slope, the radii of its bends and inflection point, are selectively
controlled by a number of factors, including the length and path of
the body 102/displaceable body segment 108, the location of the
pivot point 414 (i.e., the vertical distance of the pivot point 414
below and the horizontal distance offset from the first end 104),
the geometry of the member 420, the angle of rotation of the member
420 and the flexural properties of the body 102. For a displaceable
body segment 108 formed of a length of hose, the flexural
properties of the body account for the type of hose, the thickness
of the hose material and other similar properties. Desirably,
moving the member 420 to cause the intermediate section I to rotate
as described does not collapse displaceable body segment 108 or
otherwise interfere with feeding taking place within it except as
intended.
[0091] In the feeder 400, the second end 106 of the body 102 can be
fixed or movable. If the second end 106 is fixed, it may be
relatively aligned in the vertical direction with the first end 104
as shown in FIG. 23A, or it may be horizontally offset from the
first end 104.
[0092] The member 420 can be described as defining an offset radius
(or pivot length) between the point at which it acts on the
displaceable body segment 108 (i.e., at the member/body interface,
which is at the location of the band clamp 422 in the illustrated
implementation) and the pivot point 414. FIG. 26A is an enlarged
side elevation view showing a member 420 having approximately the
same offset radius as in FIG. 23A. FIG. 26B is an enlarged side
elevation view showing a member 420 defining a shorter offset
radius.
[0093] Overall, the geometry of the member 420 and the location of
the pivot point 414 are influenced by the design envelope of the
feeder 400. As shown in FIGS. 23A and 23B, a design goal of the
feeder 400 is to provide a minimum height difference between the
first end 104 and point at which the member 420 contacts the
displaceable body segment 108 (i.e., the member/body interface,
which is at the location of the band clamp 422 in the illustrated
implementation) to achieve a compact configuration, while at the
same time allowing the displaceable body segment 108 to achieve the
necessary geometries for both the shut off and maximum flow
positions. To accommodate the change between these geometries while
respecting the constraints of the body 102/displaceable body
segment 108, such as conservation of length (not requiring the hose
to stretch or compress) and minimum bend radius (not requiring the
hose to bend too tightly as to risk kinking it), and to reduce the
amount of stress on the body, the resulting positions of the
member/body interface (band clamp 422) can be varied in both height
and horizontal location. To work within the constraints of the
displaceable body segment 108 while permitting the second end 106
to move, a convenient method of moving the member/body interface
(band clamp 422) along an arc to achieve precise shutoff,
intermediate, and maximum flow geometries influenced the selected
geometry of the member 420.
[0094] Given a larger allowed envelope in which to provide flexing
of the body 102 between at least the first fixed end 104 and the
member/body interface (as well as between the member/body interface
and any downstream fixed point, such as a fixed second send 106, if
present), the length of the body 102/displaceable body segment 108
could be extended, permitting the member/body interface (band clamp
422) to be positioned to coincide with the pivot point 422. In this
case, the member 420 is configured to rotate about itself without
changing in height or horizontal position (i.e., a zero radius
offset), while at the same time keeping stresses experienced in the
body within acceptable levels. For example, as shown in FIG. 27A,
the member/body interface (band clamp 422) of the member 420 is
positioned to coincide with the pivot point 414. FIG. 27B is
similar to FIG. 27A, and shows schematically how the geometry of
the displaceable body segment is changed by rotating of the member
420 acting on the body through the member/body interface (band
clamp 422) at the pivot point 414.
[0095] Instead of the member 420, other arrangements can be used.
For example, an actuator similar to the actuator 230 could be
configured to move the displaceable body segment 108. Other
approaches to generating an appropriate torque and/or force applied
at a suitable location(s) are also possible. As another example, it
is also possible to have the force or torque applied very close to
or at the pivot point 414.
[0096] In one operation mode, the member 420 is moved manually to
change the angle of the intermediate section I of the body 108.
FIG. 23B is an enlarged sectioned depiction of a portion of the
body 108 of the feeder 400 of FIG. 23A, including the intermediate
section I, that is shown schematically to be filled with granular
material M, such as granular silicon. (The member 420 has been
excluded from FIG. 23B for clarity.)
[0097] As illustrated in FIG. 23B, the granular material M is not
flowing because it is constrained at the limit of its angle of
repose (in the case of granular silicon, the characteristic angle
of repose is) 31.degree.. Thus, the gravitational force that would
tend to cause the granular silicon to flow farther through the body
is balanced by the material's tendency to accumulate at its angle
of repose, so the material M remains stationary. The dashed line
illustrates schematically that the angle of repose for a leading
edge of the material M intersects with a lower side of the hose, so
no flow is possible. The position illustrated in FIGS. 23A and 23B
is referred to as the shutoff position. In the specific example of
FIG. 23A, with a hose having a diameter of 1.5 inches and being
positioned as shown, and the member 420 being configured as shown,
the member 420 was moved to a position 8.degree. below horizontal
to achieve the precise shutoff position shown in FIG. 23B.
[0098] In FIGS. 24A and 24B, the positioning of the body 108 to
achieve a minimum flow condition is shown. By moving the member 420
to a position 13.6.degree. below horizontal, the leading edge of
the accumulated material M in the intermediate section shown by the
dashed line now extends beyond a drop-off point and within an open
area of the body 108, and so the material M just begins to
flow.
[0099] In FIGS. 25A and 25B, the body 108 has been positioned as
shown to achieve a maximum flow condition. By moving the member 420
to an angle of 29.7.degree. below horizontal, maximum flow is
achieved. It was observed that greater angles below horizontal
(i.e., making the hose more vertical) did not achieve a higher flow
rate because of limiting upstream flow resistance (flow friction
and/or pressure balance).
[0100] In the representative implementation of FIGS. 23A-25B, it
was possible to achieve highly controllable flow rates for granular
silicon material across a range from 11 grams per second to 740
grams per second. Further, the flow rates were consistent as a
function of time.
[0101] As stated, the feeder 400 can be implemented for manual
operation, e.g., using a lever or other device to move the
intermediate section as desired. Thus, the feeder 400 can be
controlled manually to shutoff flow, to deliver maximum flow or to
deliver material at any intermediate flow rate. Optionally, such a
manual implementation could be achieved without requiring a source
of power or any control circuit.
[0102] In other implementations, the feeder 400 can be implemented
with a system having at least some automated control of feeding.
For example, the member 420 or other device could be configured for
control by a control circuit and one or more servo motors to
control the angle of the member 420, which could optionally be
varied during a feeding cycle.
[0103] In the described feeder implementations, only the segments
of the body and structures attached to it (such as a motor or a
member) move during operation, so there are no internal moving
parts. In the illustrated implementations, the feeders typically
eliminate at least one valve, which is one specific component
having internal moving parts. As a result, the feeders tend to be
less costly to produce and maintain and more reliable than
conventional feeding technologies having internal parts. Many
internal parts are subject to fouling during operation and are
prone to wear faster, particularly in applications where feeding of
granular polysilicon material is involved. Maintenance or repair of
such internal parts requires considerable downtime.
[0104] In the described feeder, there are fewer components and
fewer different materials that contact the material being fed than
in conventional feeders. As a result, there is a much lower risk of
contamination to the material being fed. In some implementations of
the feeder used for feeding high purity granular polysilicon, the
body 102 is made of a single length of polyurethane hose that poses
little contamination risk.
[0105] As stated, at least the displaceable body segment 108, or
the entire body 102, can be configured to be flexible so that it
can be resiliently deformed or distorted, e.g., through the
positions shown in FIGS. 2-13 and the trajectory P of FIG. 14. In
some implementations, the body is made of a section of flexible
hose, such as a hose made of polyurethane material having
sufficient thickness to withstand selected operating requirements.
Suitable polyurethane hose suppliers include, e.g., Kuriyama of
America, Inc. (see, e.g., Tigerflex Model VOLT200 at
http://products.kuriyama.com/category/tigerflex-thermoplastic-industrial--
hoses), Masterduct Inc.
(https://www.masterduct.com/material-handling-hoses), Hosecraft USA
(https://www.hosecraftusa.com/application/Material_Handling_Hoses)
and Norres Schlauchtechnik GmbH
(http://www.norres.com/us/products/industrial-hoses-technical-hoses/).
It is of course possible to use other materials (such as, e.g.,
EPDM rubber, Styrene-butadiene rubber, natural rubber, other
elastomeric materials, other resilient materials, etc.) to achieve
the desired flexibility of the displaceable body segment 108. In
addition, it would be possible to configure the body to have
multiple segments of different materials and/or to have multiple
layers. Further, in some implementations, it may be desirable to
include a bellows section along a section of the displaceable body
segment. As stated, contact metal contamination of the material
being fed can be reduced by using components and/or coatings made
of selected materials, including polyurethane.
[0106] FIGS. 17 and 18 are schematic illustrations of an
alternative implementation in which a double acting pneumatic
cylinder 230 or other linear actuator is used to impart the desired
motion to the displaceable body segment 108 or body 102 instead of
the motor 130. As shown in FIG. 17, the movable end of the cylinder
230 is connected to the displaceable body segment, and the opposite
stationary end is connected to a fixed location. The cylinder 230
would also be supplied by suitable fluid source to move back and
forth and to pivot to achieve the desired motion (such as is shown
schematically in FIG. 18) and corresponding desired feed rate. Of
course, mechanisms other than the motor 130 and the cylinder 230
could be used to move the displaceable body segment.
[0107] FIG. 22 is a schematic illustration of another alternative
implementation in which a source of vacuum or suction force is used
in the area near the outlet 307 of the feeder to help control dust
that may arise during feeding operations. In some situations, e.g.,
if material is being fed from a higher fall height, a dust cloud
can form from the falling material impacting a surface and/or
previously fed material. To address this situation, which is
usually undesirable, a suction hood 300 can be positioned to at
least partially surround the outlet 307. The suction hood 300 can
be connected via a flexible supply line 302 to a vacuum or suction
source 304. In use, a vacuum or suction force at the suction hood
300 is set to be sufficient to assist in withdrawing dust into the
hood 300, but without adversely affecting the feeding of material
in a substantially opposite direction through the outlet 307.
[0108] In the illustrated implementation, the suction hood 300 is
positioned recessed from the outlet 307 by a selected distance R,
which also helps adjust the effect of the suction force to prevent
it from adversely affect the feeding of material. In some
implementations, the suction hood 300 is recessed from the end of
the outlet by about 0.5 inch.
[0109] In view of the many possible embodiments to which the
disclosed principles may be applied, it should be recognized that
the illustrated embodiments are only preferred examples and should
not be taken as limiting in scope. Rather, the scope is defined by
the following claims. I therefore claim all that comes within the
scope and spirit of these claims.
* * * * *
References