Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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Field of the Invention
~ his invention relates to product pumps that move product
from the discharge of a hopper, bin, silo or other device
containing the product and delivering the product to one
or more collecting points by means of a dense-phase, posi-
tive-pressure, pneumatic conveying system, and the product
pump assembly and product pump therefor. It more particularly
relates to such pump assemblies which are used to discharge
into pressurized vessels or into liquids that cause a high
system back pressure. It also relates to such pump assemblies
which can be used to convey products that are light and
fluffy or otherwise have poor flow characteristics.
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ack~ound of the Invention
; Existing product pumps rely on gravity to transfer
the product from a hopper, or the like, into a pump chamber.
However, gra~ity flow limits a pump to use with free flowing
products. Also, product pumps in the past were unable to
discharge into a vessel that gave a high back pressure.
Small quick cycling product pumps were frequently used
as a means of introducing a product into a pneumatic conveying
line. Each successive cycle of the pump pushed a new charge
of product into the conveying line and the air trapped between
each charge pushed the previously-loaded charge further
along the conveying line. These devices are normally cycled
with electric or pneumatic controls incorporating adjustable
timing devices. The timers are arranged to vary the time
of each function within the cycle so that the system can
be adjusted to meet varying field conditions. The cycle
starts with the product inlet valve open and product flows
by gravity from the hopper, or the like, into the product
pump. After a short fill time, the product inlet valve
is closed and the air pressure is applied to the pump chamber
to force the product charge from the pump into the conveying
line. After the air flow is shut off, air pressure remains
in the product pump and in the conveying line. Some of
this air will dissipate through the product charge and out
the discharge of the conveying system providing a delay
time is employed between the compressed air shut off and
the opening of the product inlet valve. In actual practice,
a delay time is selected that permits some compressed air
to bleed off down the pipe with the remaining compressed
air blowing up into the product when the inlet valve is
' opened. Both the time required to bleed off the compressed
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air and the air blowback reduce the overall delivery rate
of the pneumatic conveying system. Additionally, the higher
'the back pressure at the discharge of the system, the greater
ithe inlet venting problem. Also, a high rate of blowback
at the inlet feed point often causes a dust problem. It
;is further noted that this type of system cannot be used
to transport to a pressurized vessel or into a Liquid that
presents a large hydraulic back pressure.
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Obiects ~ the Invention
Accordingly, it is the principal object of the present
invention to provide an improved means for moving product
by dense phase positive pressure pneumatic conveying means
from a storage container to a collecting point.
Another object of the present invention is to provide
a novel conveying system which can convey products that
are light and fluffy or otherwise have poor flow character-
istics.
A further object of the present invention is to provide
a novel system that can discharge the product into a high
pressurized vessel or into a liquid that causes a high system
back pressure.
A still further object of the present invention is
to provide a novel conveying system which eliminates or
minimizes the dust problems previously experienced.
Another object is to provide a novel pumping system
with increased hourly conveying rates.
A further object is to provide a pump which completely
discharges the product from its product chamber during each
cycle.
A still further object is to provide a novel pump system
which decreases the time required to discharge the product
from the pump, and which has an overall improved capacity.
Another object is to provide a novel pump which permits
the pump to be designed with a low profile to reduce the
required head room.
A further object is to provide a novel pump design
which elirninates the need for a lower compressed air line
into the pump.
A sti11 ~urther object is to provide an inlet valve
design which utilizes an improved and novel means to close
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.
24 is seen to comprise a compressed air supply 42, a pressure
regulator 44 and a pressure gauge 46 leading to a two-way
I valve 48. A four-way switch valve 50 is provided for con-
j trolling the compressed air supply. It can be a solenoid
actuated, spring-return, four-way two-position valve such
as are commercially available from the Parker-Hannifin Corpora-
tion and the Arrow Corporation. One position of switch
valve 50 directs the compressed air into the product pump
l,14 during the conveying portion of the cycle, and when the
I valve is in this position all other ports are unused. The
second position of switch valve 50 directs the compressed
; air into an ejector 52. The vacuum port of ejector 52 is
connected through switch valve 50 to the line 56 going to
the air inlet pipe product pump 14. This is the same line
that is used to deliver the compressed air to the product
pump during the conveying portion of the cycle. When the
conveying portion of the cycle is complete, switch valve
50 shifts and sends the compressed air to the ejector 52.
The positive pressure remaining from the conveying portion
of the cycle is quickly reduced to a negative pressure and
feed valve 34 is thereby opened. The negative pressure
in the product pump eliminates the compressed air that in
other pumps vents through the inlet valve and into the product.
A line filter 58 is provided between product pump 14
;'and switch valve 50 on line 56. Line filter 58 effectively
prevents dust from entering switch valve 50 when product
pump 14 is placed under a negative pressure. Line filter
58 is automatically purged of dust during the next pressure
portion of the pump's cycle.
When product pump ~4 is in operation, the hourly conveying
rate is dependent upon the time required to load product
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the product inlet and to effectively hold it in the closed
position during the product conveying cycle.
Another object is to pr~ide a novel product pump which
insures that t~e inl~t ~alve will not open prematurely and
allow compressed air to escape into the material which may
retard the flow of material into the pump and create dust
problems.
Other objects and advantages of the present invention
will become more apparent to those persons having ordinary
skill in the art from the following description taken in
conjunction with the accompanying drawings.
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Brief Description of the Drawings
Figure 1 is a schematic view of a product pump assembly
embodying the present invention.
Figure 2 is an enlarged fragmentary view of the product
pump of Figure 1 illustrated in isolation.
Figure 3 is a top plan view of the product pump of
Figure 2.
Figure 4 is an enlarged fragmentary side view of the
check valve of Figure 1.
Figure 5 is a graph illustrating the cycle of the product
pump of Figure 1.
Figure 6 is an electrical schematic and a front view
, of the control panel of the product pump assembly of Fiyure
; 1.
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Description of the Preferred Embodiment
_ . . . . . .. .
Referring to Figure 1, an apparatus embodying the present
invention is illustrated schematically at 10. Apparatus
lo is shown to include a product source 12, and a product
pump shown generally at 14 having, as shown in Figure 2,
a product chamber 16, a product receiving inlet 18, a product
discharge outlet 20 and an air inlet pipe 22. ~n air supply
system shown very generally at 24 supplies pressurized air
into air inlet pipe 22 thereby forcing the product in product
chamber 16 out product discharge outlet 20 through a delivery
line 26 to the product collector 28.
Product pump 14 is best illustrated in Figure 2. It
is seen therein that air inlet pipe 22 enters the product
pump through the lower half thereof and an elbow member
30 directs the pressurized air upwards into the cone member
32 of the feed valve shown generally at 34. Thus, when
the pressurized air is forced by air supply system 24 through
air inlet pipe 22 into product pump 14, the air is forced
up against the inside surfaces of cone member 32 thereby
causing it to move upwardly until it is seated against the
resilient valve seat assembly 36 at product receiving inlet
18. The force of the incoming air not only moves cone member
32 into its seated position but holds it firmly against
the seat thereby defining an effective seal preventing addi-
tional product to gravity flow into the chamber and pressurized
air from flowing out the inlet. Additionally, when air
supply system 14 is in its vacuum state wherein air is drawn
through air inlet pipe 22 out of product chamber 16, cone
member 32 is caused to move down into its open position,
as shown in Figure 2. This vacuum that is thereby created
helps to fill chamber 16, which is especially important
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when loading light or fluffy particles. It is further obvious
from Figure 2 th~t when the air is forc~d into product chamber
16 and against the in~erlor sur~ace of cone member 32 it
,is thereby deflected by the cone member towards the chamber
floor 38 of product chamber 16 causing a sweeping action
, of the product off the floor 38 and out the product discharge
outlet 20. This helps provide for an effective-complete
discharge of the product during the conveying cycle~
A check val~e 40 is positioned on delivery line 26
between product pump 14 and the product collector 28 at
a location in close proximity to product discharge outlet
20. Check valve 40, which is shown in greater detail in
Figure 4, is used to isolate the air pressure in delivery
line 26 and stop the back flow of compressed air into product
, pump 14 when pump 14 is placed under negative pressure.
Check valve 40 can be constructed as shown in Figure 4 with
the air from the product pump passing through the two-inch
I delivery line and forcing the 2.5 inch diameter Neoprene
ball 42 off of the seat 44, which is adjacent the valve
flanges 46, and up against four spaced, upwardly-curved
members 48 with the air flowing between the members into
the outflow delivery line. ~hen the air is sucked down
the delivery line9 ball 42 is caused to be seated in seat
44, as shown in Figure 4, thereby blocking the air flow
back into the product pump.
, Air supply system 24 illustrated in Figure 1 thus performs
three functions: (1) it supplies compressed air to product
pump 14 to force the product out of the product discharge
outlet 20, (2) it creates a suction in the product chamber
; 16 during the filling times pulling the product into the
chamber, and ~3J it opens and closes feed valve 34. System
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into the pump and the time required to discharge the product
from the pump into delivery line 26. To maintain the design
rate, the pump ~ust discharge the product completely to
make room for a new charge of product. Ejector 52 is used
to create a negativ~ pressure which then forces the product
into the pump. This arrangement reduces the time required
to load the product into the pump. The product pump operation
is initiated when the power is turned on. The pump sequence
ic controlled by three adjusta~le timers.
Referring to Figure 6, the sequence of operation of
the timers is as follows:
1. The off-on switch SWl turns the power on for the
control panel. Control switch SW2 is a selector switch
used to place the control in either manual ~hand) or automatic
(auto) operation. The normal position for this switch is
the auto position. The control panel is also furnished
with two momentary contact push button stations PBl and
PB2 to provide for manual filling or manual conveying.
2. For normal operation, control switch SW2 is placed
in the "auto" position and the panel is turned on by placing
switch No. 1 in the "on'l position. This will energize the
control relay CRl, the ejector timer TDl and the fill timer
TD2. Also, the two-way valve solenoid SOL 1 and the four-way
valve solenoid SOL 2 are activated. When energized two-way
valve 48 opens to turn on the compressed air to the system.
Four-way valve 50 shifts to direct the compressed air to
ejector 52 and connects the negative pressure line to product
pump 14.
3. When the ejector timer TDl times out, two-way
valve 4~ closes and four-way valve 50 shifts to the conveying
position. Fill timer TD2 continues to time until the timer
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times out and energizes two-way solenoid SOL 1 and timer
delay TD3. When energized, two-way solenoid SOL 1 opens
and conveying is started. When timer TD3 times out, conveying
stops and the se~uence retur~s and activates ejector timer
TDl and fill timer TD2.
4. To arrange the control for manual operation, selector
switch SW2 is placed in the "hand" position. For manual
filling, push button PBl is pressed and for manual conveying
push button PB2 is pressed. Interlocking contacts are provided
so that only one push button can be energized at any one
time.
5. Three pilot lights are provided on the control
panel. A white pilot light ~1 is used to show when the
panel is turned on, a green pilot light P2 will show when
the product pump is filling and amber pilot light P3 shows
when the system is conveying.
n conclusion, the pump sequence starts at the beginning
of the fill cycle and tirnes through the following sequence:
1. When the power is turned on, ejector 52 and the
fill timers TD2 are energized along with the two-way and
four-way valve solenoids, SOL 1 and SOL 2. Two-way valve
48 opens to turn on the compressed air. Shift valve 50
shifts to direct the compressed air to ejector 52 and connects
the negative pressure line 60 to the product pump.
2. ~hese two-way valves remain in this position until
ejector timer TDl times out and de-energizes both valve
solenoids. When de-energized, two-way valve 48 closes to
shut off the compressed air and shift valve 50 shifts to
align the compressed air line 56 to product pump 14. The
ejector timer TDl is adjustable from zero to 1.5 seconds,
and the normal setting is between .5 and 1.0 seconds, as
best illustrated in Figure S.
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3. When energized, fill timer TD2 times for a pre-
set time then energizes the convey timer and the two-way
valve solenoid 48. The fill timer TD2 is ~dj~stable from
zero to 1.5 seconds, with the normal setting being between
.8 and 1.2 seconds, as best illustrated in Figure 5. When
setting ejector 52 and the fill timers, it is noted that
the ejector time setting is never greater than the fill
ti~er setting.
4. When two-way valve 48 is energized it opens to
turn on the compressed air, which is directed through switch
valve 50 to product pump 14 and conveying commences. The
convey timer is adjustable from zero to .6 seconds, with
the normal setting being between .1 and .4 seconds.
5. When the convey timer times out, the two-way valve
48 closes to shut off the compressed air and the sequence
is complete. Product pump 14 continues to cycle, as explained
above, until the power to the timer is turned off when the
desired amount of material has been conveyed from product
source 12 to product collector 28.
From the foregoing detailed description, it will be
evident that there are a number of changes, adaptations
and modifications of the present invention which come within
the province of those skilled in the art. However, it is
intended that all such variations not departing from the
spirit of the invention be considered as within the scope
thereof and as limited solely by the appended claims.
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