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Description  |
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BACKGROUND OF THE INVENTION
In the developing of films such as x-ray and photographic films, it is
known to utilize a series of treatment fluids, for developing, fixing,
washing, and possibly still other treatment steps.
When automatic machinery is used for such film developing, these treatment
fluids are usually placed in a series of tanks, through which the films
being developed are then transported, by means of transport roller racks
extending down into these tanks.
During operation of such automatic film developing machines the fluids in
the tanks gradually become depleted, and must therefore be replenished.
Generally, the treatment fluid in any given tank consists of a mixture of
chemicals and water. For proper replenishment, there must be maintained
not only the overall fluid level in the tank, but also the relative
concentration of the chemicals. This replenishing requirement has
heretofore not been completely satisfactorily met. The prevailing
technique for replenishing involves pouring the replenisher
ingredients--the chemicals--into a container, stirring these chemicals in
the container, and then pouring the resultant mixture into the tank, in
quantities and at intervals such as to maintain in the tank the desired
level and proportions of chemicals.
It is known to automate certain aspects of this technique. For example, our
prior U.S. Pat. No. 3,752,052, issued Aug. 14, 1973, teaches automatic
control of a pump which delivers replenisher fluid to the machine
treatment tank as needed.
What is not disclosed in this prior patent is how to obtain initially the
correct replenisher fluid mixture, which the pump can then automatically
deliver to the developing machine.
There are a wide variety of mixtures which are used for replenishment in
film developing. For example, a replenisher for the developer fluid may
consist of a developing agent (such as sold by Kodak under the commercial
name Elon), anhydrous sodium sulfite, monohydrate sodium carbonate, and
sodium hydroxide in aqueous solution.
Many other ingredients and proportions are possible.
Although for some of these mixtures the chemicals are available from
manufacturers in premixed form, these are generally impractical for
modern, high-speed automatic developing machines because of the high cost
of such premixed chemicals. As a practical matter it is therefore
necessary to acquire the individual chemicals in separate bulk containers,
and to mix them at the site of the machine. In any event, the water is
admixed on site since it determines the concentration of the final
replenisher mixture, which must be adjusted locally in accordance with
current operating conditions.
This on-site mixing, by the prevailing technique previously described, is
accompanied by undesirable side effects.
There is fluid waste in pouring into and out of the container in which the
mixing is performed. Some of the fluids used are quite "messy", leading to
unsightly premises where the mixing takes place and sometimes even to
conditions which are potentially hazardous to health and property.
The mixture itself suffered from the fact that the ingredients are
generally quite difficult to blend homogeneously and uniformly unless
vigorously stirred. Moreover, this stirring sometimes had to be repeated
at frequent intervals to overcome the tendency of the chemicals to
reseparate. This in turn further accentuated the other problems of
spillage previously described.
Finally, over a period of time the chemicals of the replenisher mixtures
may react with each other, and/or may be oxidized by the air which has
access into the mixture both during the stirring and also later, as
portions of the mixture in the container are gradually emptied into the
machine. This caused deterioration of the replenisher mixtures formed by
the prevailing technique under discussion.
While these problems occur primarily in the film developing industries, in
other industries, typically chemical or biochemical, where the system of
the invention can also be used, as explained hereinafter, similar
difficult problems exist caused by the lack of equipment capable of mixing
or blending difficult to mix components.
SUMMARY OF THE INVENTION
We have now found that an appreciable improvement can be made in the
replenishment of chemicals used in automatic film developing machines by
means of a unique system which automatically mixes the fluids to be used
in replenishing a particular developing machine tank, and pumps these
mixed fluids toward their intended destination, like tanks or other
containers.
In the system of the invention, the mixing is performed under conditions of
fluid movement and pressure which are particularly conducive to intimate,
uniform mixing of hard-to-mix fluids.
Air may be excluded so that no oxidation of the fluids takes place.
Pumping movement may be continued while the mixing takes place.
The system can be completely closed, from the original bulk containers for
the separate ingredients, up to discharge of the mixture into the
developing machine tank. Yet due to the transparent nature of the plastics
of the chamber, the operation can be observed as desired.
The system of the invention includes a cylindrical chamber which houses at
one end a curved-vane impeller rotatable in the manner of the impeller of
a centrifugal pump. Concentric within the chamber is an inner cylinder
which stops near the impeller at one end, but extends fully to the end of
the chamber at the other. In operation, the fluids to be processed are
introduced under pressure into the annular space between the inner
cylinder and the outer chamber wall. They flow downwardly, entering the
inner cylinder in the region around the impeller. In this flow, they
encounter the rotating impeller and are urged by it back toward the outer
chamber wall. The inward-urging pressure under which the fluids are
introduced is so proportioned relative to the outward-urging force exerted
by the impeller that there is a net flow of the fluids past the impeller
into the inner chamber. However, the local agitation to which these fluids
are subjected by the impeller during such passage has been found to
provide excellent mixing for the fluids.
The fluids then continue to flow through the inner cylinder and out of an
outlet at its end remote from the impeller. This outlet may be connected
directly to the particular developing machine tank for which the mixture
is intended.
In the mixing system of the invention, there prevail motions which are
conductive to optimum mixing. The liquids are forced within the confines
of the outer annular chamber, assisted by gravity flow, when the system is
positioned as illustrated in FIG. 1. This flow of the liquids from the
inlet at the top of the cylinder towards the bottom causes an initial
contacting of the liquids.
The impeller creates and maintains yet other flow patterns. Due to its
position and shape there is established a flow pattern having a rotary,
swiveling motion. Also a flow pattern is created which radiates towards
the wall of the outer cylinder while simultaneously being channeled
between the blades of the impeller inwardly into the inner cylinder. Thus
a certain hydraulic shearing action is created. The fluids in motion are
also forced toward the inside of the inner cylinder where, due to the
pressure under which the liquids are introduced into the cylinder chamber,
the liquids ascend in the inner cylinder toward the outlet.
A review of the mixing literature emphasizes that mixing or blending
systems which create several flow patterns are those which are most
efficient for achieving what is intended. What is noteworthy is that in
the mixing system of the invention, there is provided a downward and an
upward flow, which flows are separated between the outer and inner
cylinders respectively. Also noteworthy is that the mixing can be
regulated not only by regulating the rotary speed of the impeller blades
but also by regulating the speed of the inlet and outlet flows, thus
allowing for optimum residence time of the chemicals in the system
depending on the liquids to be mixed.
In the mixing system of the invention the impellers, though shown as fixed
members, can be constructed to be movable to any desired position,
permitting adjustment of their angle with respect to the walls of the
system as is deemed best.
If desired, baffles can be positioned on the walls of the inner (or of the
outer) cylinder, but such satisfactory mixing is accomplished without
baffles that such would seem superfluous. Likewise, if desired, blades can
be positioned at various points along the axis of the impeller.
The mixing system of the invention presents an unusual combination capable
of providing highly effective mixing due to the unique construction of the
system which creates circular, axial and other flow patterns, including
downward and upward flows, all of which are conducive to maximum mixing.
Also noteworthy is that in the vicinity of the impeller blades, where the
two cylinders communicate, these various flow patterns prevail
concurrently, maximizing blending conditions. Accordingly, the mixing
system of the invention is useful in mixing any fluids, especially hard to
mix fluids in the chemical, biochemical, food and related industries.
The mixing system of the invention can be used for blending viscous
materials, pastes, gel mixes like elastomers, plastics, polymers, heavy
solutions or dispersions, lacquers, paints, adhesives, inks, resin
solutions, soaps, components in the food industry such as oleomargerine,
dyes, oils, and whereever it is desired to disperse, dissolve or mix
materials in the drug, cosmetic or other industries.
The above-mentioned dispersions can be fluid in fluid dispersions, in
contrast to solutions, or solids in liquids (with proper adjustment being
made to the inlet and outlet if necessary). Such solids can be made to
dissolve during mixing in the apparatus of the invention.
The mixing system can be used where gases are to be excluded from the
liquids, such as when it is desired to avoid oxidation of the components.
On the other hand, the system can be made to admit controlled amounts of
desired gases, one example being hydrogen when selected hydrogenation
under even and maximum blending is called for.
It is apparent that the apparatus is highly versatile.
As illustrated, the walls of the cylinders are ideally constructed of
transparent or translucent plastics to permit easy observation of the
interior of the mixing system.
If desired cooling or heating means can be made to heat or cool the fluids
at any time during the operation.
Other advantages and applications of the system of the invention will
become readily apparent to one skilled in the art from the description
which follows.
The means which supplies the fluids under pressure preferably does so in a
pulsating manner. This may be accomplished, for example, by bellows-type
pumps such as taught in our U.S. Pat. No. 3,965,758, issued June 27, 1976.
Together with the action of the impeller, this creates a pulsating effect
of alternate compression and decompression within the cylindrical chamber
which further enhances the quality of the mixing action.
Accordingly, it is a primary object of the invention to provide an improved
system for replenishing automatic film developing machines.
It is another object to provide such a system which accomplishes improved
mixing of the film treatment fluids.
It is another object to provide such a system which accomplishes mixing at
the same time as pumping.
It is another object to provide such a system which continuously supplies a
mixture of fluids directly from the containers in which the separate
fluids are commercially available.
A fuller understanding of the invention will be had by referring to the
following description of the preferred embodiments thereof, taken in
conjunction with the accompanying drawings, wherein like reference
characters refer to similar parts throughout the several views in which:
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is an overall isometric view of a mixing and pumping system
embodying the invention;
FIG. 2 is a partial, isometric view of that area of the mixing and pumping
system which is in the vicinity of the impeller and the blades, partially
broken away to show structural detail;
FIG. 3 is an exploded view of the mixing and pumping system showing
particularly the components which comprise the mixing portion of the
system;
FIG. 4 is a side elevational view, partly in section, of a portion of the
apparatus of FIG. 1 taken along line 3--3 in FIG. 1;
FIG. 5 is a cross-sectional top view of the apparatus of FIG. 4 taken along
line 4--4;
FIG. 6 is a cross-sectional top view of the apparatus of FIG. 4 taken along
line 5--5;
FIG. 7 is a partial isometric view of the mixing and pumping system showing
an alternative lid construction;
FIG. 8 is a top plan view of the alternative lid construction illustrated
in FIG. 7;
FIG. 9 is a cross-sectional view of the mixing and pumping system of FIG. 7
taken along line 9--9; and
FIG. 10 is a sectional view of the alternative lid construction of FIG. 8
taken along line 10--10;
FIG. 11 is a top plan view of an alternative embodiment of the impeller of
the mixing and pumping system.
DESCRIPTION OF THE PREFERRED EMBODIMENT OF THE INVENTION
Referring now to the drawings, these show an assembly 10 which include an
electric motor 11. Attached to the housing of motor 11, is a base 12 upon
which is supported a cylinder 13. At the end of cylinder 13 remote from
base 12 there is a lid structure 14 which closes that end of cylinder 12.
The base 12, cylinder 13 and lid 14 define an enclosed cylindrical
chamber.
Within cylinder 13 there is an inner cylinder 15, of lesser diameter than
cylinder 13. This inner cylinder 15 terminates at the same lid 14 as does
cylinder 13. On the other hand, the end of inner cylinder 15 nearest the
base 12 does not extend all the way to that base, but stops short, so that
this end of inner cylinder 15 remains free, spaced from base 12 by a gap
16. Positioned concentrically with respect to both cylinders 13, 15 is an
impeller 17 having curved, outwardly extending blades 18 (see particularly
FIG. 5).
The blades 18 are preferably substantially equal in length, extending
outwardly in a convex, radially symetrical manner. The blades 18 are also
preferably placed askew from the radial axis of the impeller 17. The
resulting configuration generally causes the blades 18 to radially overlap
as illustrated in FIG. 5. It is also possible to provide blades 18 the
position of which are adjustable, to accommodate varying applications by
varying the above parameters as necessary, as illustrated in FIG. 11. For
example, this may be accomplished using blades 18 having flanges 40 which
are adjustably attached to impeller 21 by studs 41 and bolts 42. Other
means are possible which will produce a similar result.
The diameter of the impeller 17 (with its blades 18) is preferably such
that the tips of the blades extend approximately to the perimeter of the
inner cylinder 15. Such an impeller 17 would be positioned adjacent base
12 having an axial dimension such that the impeller blades 18 nearly but
not quite fill the gap 16 between base 12 and the free end of inner
cylinder 15. The blades 18 could also extend upwardly at a distance
greater than the gap 16 if desired. It is also possible, when the impeller
blades are dimensioned so as not to fill the gap 16, to utilize an
impeller 17 which extends radially to, or even beyond, the perimeter of
the inner cylinder 15, if desired.
A shaft 19 extends upwardly from impeller 17 to a bearing 20 (best visible
in FIG. 3) within which the shaft 19 is journaled for rotation. The lower
end of impeller 17 is formed by a cylindrical extension 21 which fits into
a corresponding, although slightly wider recess 22 within base 12. In the
bottom of recess 22 there is provided a bearing 23 which journals
extension 21 for rotation within recess 22.
When the electric motor 11 rotates, its shaft produces rotation of a set of
magnets peripherally surrounding the recess 22 within base 12. With
extension 21 there are corresponding magnets. As a result, when the motor
11 rotates, magnetic coupling causes extension 21 to likewise rotate
essentially in unison with the rotation of the motor. This imparts
corresponding rotation to impeller 17.
The lid 14 illustrated in FIGS. 1-3 has tangentially protruding therefrom
an extension pipe 24. As is particularly apparent from FIG. 4, this
extension 24 opens into the outer cylinder 13. Consequently, liquid
flowing through pipe extension 24 toward outer cylinder 13 (i.e., in the
direction of arrow 25 in FIG. 4) is introduced into the annular space 26
between inner and outer cylinders 15, 13.
In the lid 14 illustrated in FIGS. 1-3 there is also provided a generally
centrally located opening 30, providing a means for the passage of fluid
from within inner cylinder 15 to the outside of the assembly 10. An outlet
pipe 31 may be connected to this outlet opening 30, the remote end of this
pipe leading to the intended destination of the fluids processed through
unit 10 which may, for example, be one of the tanks of an automatic film
developing machine.
There is shown in FIGS. 7-10 an alternative embodiment of the lid 14'. The
lid 14' is provided with an outlet opening 30' which communicates with the
inner cylinder 15 as previously described. In this embodiment the outlet
30' is positioned askew from the center of the lid 14'.
The lid 14' of FIG. 6 is also provided with a plurality of inlets 35 which
communicate with the annular space 26 located between the inner and outer
cylinders 15, 13. These inlets 35 may be combined to form a manifold which
joins, for example, at a junction coupling 29, the purpose of which will
be described below. In this manner, a fluid may be introduced into the
annular space 26 with improved uniformity. It is also possible for the
inlets 35 to be grouped together to form two or more manifolds, each of
which is capable of introducing a separate fluid into the annular space
26, if desired.
Pumps 27, 28 (FIG. 1) have their outlets connected to tangential extension
pipe 24 through a junction coupling 29. This coupling 29 may take any
conventional form consisting of internal passages through which liquid can
flow from the pumps 27, 28 toward pipe 24 but not in reverse. To that end,
conventional one-way valves may be associated with the internal passages
within junction coupling 29.
The pumps 27, 28 are preferably of the pulsating bellows variety
illustrated and may be actuated, as previously stated, in the manner
disclosed in our prior U.S. Pat. No. 3,965,758 issued June 27, 1976.
In operation, this system functions as follows.
The pumps 27 and 28 are respectively coupled to separate containers of the
several fluids which are to be supplied in mixture as replenisher for our
automatic film developing machine. For example, the fluid supplied to one
of these pumps may be water, while the fluid supplied to the other pump is
another component of the replenisher. Due to the functioning of pumps 27,
28, these fluids are then forced under pressure through junction coupling
29 and into pipe 24, and through that pipe into the annular space 26
defined between inner and outer cylinders 15, 13.
Assisted by gravity, the fluids thus received within this annular space 26
in due course reach the gap 16 which exists between the free end of inner
cylinder 15 and base 12. These fluids then tend to flow radially inward
through gap 16 into the cylindrical space defined within inner cylinder
15.
At the same time, however, impeller 17 is rotating under the drive of motor
11. The direction of the rotation of the motor 11 is preferably such that
the blades of impeller 17 turn in the direction indicated by arrow 32 in
FIG. 5. It will be recognized that rotation of this impeller, as
described, will exert a centrifugal force upon the fluids seeking to pass
from annular space 26 through gap 16 into the interior of cylinder 15.
Thus, there will be in the general area of the impeller 17 two
counteracting forces operating upon the fluids. One force will be that
which tends to cause them to flow radially inward, while the other one is
that which tends to cause them to flow centrifugally outward. This causes
an intermingling and blending under intense pressure and movement of the
fluids supplied respectively from pumps 27 and 28 both within the annular
space 26 and as they ultimately reach the interior of cylinder 15. The
fluids so blended and still retaining to some degree the mingling and
circulating action impressed upon them in the region of impeller 17 then
continue to rise within inner cylinder 15 and ultimately are discharged
from assembly 10 through outlet 30 and outlet pipe 31.
We have found that this system provides a remarkably effective mixing and
pumping action for fluids such as are needed to replenish the treatment
tanks of automatic film processing machines.
The fluid inlets of pumps such as shown at 27, 28 in FIG. 1 may draw their
respective fluids directly from the conventional storage or shipping
containers of these fluids. There is no separate mixing container
required. The system is completely closed and does not permit any spillage
or involve "messy" handling, nor is there any loss of fluids during
handling through the system.
A particularly desirable feature is that the system is self-purging of air,
so that the harmful oxidation which occurs in the presence of air is
strongly suppressed.
The mixtures produced and supplied through outlet pipe 31 are particularly
satisfactory for use in automatic film developing machines. Their
uniformity is very high and the tendency for their ingredients to separate
out is very low.
The proportions of fluids in the mixture can be readily controlled through
the operation of the pumps, such as shown at 27, 28.
Moreover, the use of pulsating type pumps, such as the bellows type pumps
27 and 28 is particularly desirable in the present system for the
following reasons. The resulting pulsating flow of fluid into the gap 16
within unit 10 causes a pulsating variation in local conditions within the
fluid within this gap which, we have found, further contributes to the
thorough, intimate and uniform mixing of these fluids. This pulsating
effect also tends to cause some variation in the speed of rotation of the
impeller 17, which tends to slow down as a fluid impulse is felt in its
vicinity, while speeding up as the fluid impulse diminishes. This
variation in impeller speed further enhances the intimacy of mixing.
It will be understood that many variations are possible without departing
from the scope of the invention. For example, the dimensions of the
equipment will be adapted to the particular requirement of flow rate and
other quantitative parameters.
A magnetically driven impeller is shown to prevent the ne | | |
