Note: Descriptions are shown in the official language in which they were submitted.
CA 02255786 1999-04-O1
IN THE CANADIAN PATENT OFFICE
TITLE: Semi-Frozen Food Product Producing Machine
Field of the Invention:
The present invention relates to semi-frozen food product producing machines,
including
frozen carbonated beverage (FCB) machines, and in particular to the cooling
and
beverage blending systems thereof and the drive and control systems therefor.
B ackground:
FCB making and dispensing machines are known in the art and generally utilize
a
freezing cylinder for producing a slush beverage therein. An evaporator coil
is wrapped
around the exterior of the cylinder for cooling the contents thereof. A
scraper mechanism
extends along the central axis of the cylinder and is rotated to scrape thin
iced or frozen
layers of the beverage or food product from the internal surface of the
cylinder. A
carbonator tank is used to produce carbonated water by the combination therein
of water
and pressurized carbon dioxide gas (C02). The carbonated water and a syrup are
then
combined in the desired ratio and introduced into a separate blender bottle.
The properly
ratioed beverage is then delivered from the blender bottle into the freeze
cylinder. A
problem with this approach concerns the warming of the contents of the
carbonator and
blender bottle wherein high pressures are required to maintain the desired
level of
carbonation at such elevated temperatures.
An ongoing problem with FCB machines, and related to the foregoing, is the
amount of
cooling that is required to make and maintain a beverage in a semi-frozen
state. This
cooling demand is especially great during times of high use when, as drinks
are being
dispensed, new ambient temperature water and syrup are continually being added
to the
cylinder from the blender bottle. A strategy has long been needed to provide
for high
draw capacity in an FCB machine without resorting to the expedient of
requiring ever
CA 02255786 2001-11-13
larger refrigeration compressors and systems with their concomitant increase
in machine
purchase cost, cost of operation and noise of operation. A further problem
with prior art
FCB machines concerns their mechanical or design eomple~city, This Complexity,
in
terms of nwxvbers of parts, adds cost with respect to manufacture and
maintenance, and
also negatively impacts reliability. Accordingly, it would be vexy desirable
to have an
FC13 machine that is less expensive and easier to manufacture and maintain.
A further drawback to FCB machines is the fatt that the scraper mechanism
inhet'ently
requires a shaft portion thereof to extend through a cylinder end for
connection to a drive
motor, thereby requiring a dynamic seal. This requirement stems from the fact
that the
drive m~ethanism is extorior o F the cylinder and can x~ot come into direct
contact with the
food product therein. Naturally, such seals are subject to wear and consequent
leaking,
especially where the beverage contents are under pressure, as is the case for
a frozen
carbonated beverage. Major service problems with such machines are related to
failed or
leaking scraper shaft seals. Accordingly, it would be very desirable to be
able to
eliminate such seals, yet have a scraper drive mechanism that does not create
food
compatibility/contaet problems, and that has sufficient strength to operate
the scraper
against the considerable resistance it encounters whop producing the desired
frozen food
product.
SUMMARY OF THE INVENTION:
2 0 In a preferred embodiment of the present invention, a dual purpose
carbonator/blending
bottle, "blendonator", is connected to a source of beverage syrup, a source of
potable water
and to a source of pressurized carbon dioxide gas. A pair of ratio valves
provide for metering
the water and syrup, which combined beverage then flows into a serpentine heat
exchange
coil and then into the blending bottle. Both the blending/carbonating bottle
are retained within
2 5 an ice bank cooled water bath tank. A refrigeration system provides for
cooling an
evaporator located in the water tank for forming the ice bank thereon. The
blending
bottle includes an outlet for connecting the interior volume thereof to a
freeze cylinder.
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The freeze cylinder also includes a further evaporator coiled around an
exterior perimeter
thereof. The freeze cylinder evaporator is connected to and cooled by the same
t~efrigeration system that cools the evaporator in the water bath tank. A
scraping
mechanism within the cylinder provides for scraping frozen beverage from the
inner
surface of the cylinder. A control mechanism provides for controlling the
refrigeration
system and the cooling of both evaporators.
In operation, the dual purpose blending bottle combines the functions of the
separate
carbonator and blending bottle system found in_the prior art. Thus, the
improved blender
bottle serves both to carbonate the beverage and to retain a volume of a f
nished amount
thereof. As it is located in the water bath tank, the volume of beverage
thezein is cooled
by heat exchange transfer with the ice fomted on the ice bank evaporator. A
further
volume of the beverage is retained in the serpentine coil and also maintained
at a suitably'
cool temperature by heat e~cchange contact with the cooled water of the water
bath. The
beverage is therefore pre-cooled to a temperature just above its freezing
point befot~e
delivery to the freeze cylinder. Thus, far less cooling power is needed to
reduce the
beverage to a frozen state, as would be the case in prior art FCB machines
where the
beverage is typically at a much higher ambient temperature just prior to its
introduction
into the freeze cylinder. Those of skill will understand that the ice bank
provides for this
extra cooling, which ice bank is formed by operation of the refrigeration
system to build
2 0 ice on the water bath evaporator. In the present invention, this added
cooling is attained
with a similar or even smaller sized refrigeration system components than
would be used
in comparable output prior art FCB machines. This enhanced coolxx~g ability is
obtained
by the strategy of building an ice :bank on the water bath evaporator
ostensibly during
times of non-dispense and/or when the freeze cylinder evaporator is otherwise
not being
cooled.
A further advantage of the present invention is seen in the method of
controlling the
operation of the refrigeration system and the cooling of both evaporators
thereof. The
control system provides for directing refrigerant to either of the evaporators
as is most
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efficient. Thus, if the FCB machine is in a "sleep" mode overnight when no
drinks will
be dispensed therefrom, the control can direct all the cooling ability if the
refrigeration
system be utilized to build up the ice bank at that time. Also, as is known in
the art, when
the beverage in the cylinder has reached its maximum desired viscosity, the
cooling of the
freeze cylinder evaporator must be stopped. Since a semi-frozen beverage can
warm
quickly to an unacceptably low viscosity the compressor must then be turned
back on.
However, and especially where the FCB machine has more than one freeze
cylinder, the
compressor can be turned on and off very frequently leading to damaging short
cycling
thereof. However, in the present invention, rather than stop the operation of
the
compressor, the control herein has an option to continue the operation of the
compressor
to cool the ice bank evaporator if further ice bank growth is needed or can
otherwise be
accommodated. Thus, when cylinder cooling is again required, refrigerant can
again be
directed thereto whereby a short cycling thereof can be avoided. This strategy
of being
able to alternate cooling between the cylinder evaporators and the ice bank
evaporator
presents a major advantage for compressor longevity, as most, if not all,
short cycling can
be avoided.
A further advantage of the present invention concerns the ability of the
electronic control
system thereof to obtain more efficient cooling of the freeze cylinders. The
present
invention uses a control strategy that can more accurately maintain a pre-
selected
temperature differential between the inlet and outlet temperatures of the
freeze cylinder
evaporators. A control algorithm utilizes a proportional integral differential
control
approach that safely permits a much narrower temperature difference so that a
greater
length of each freeze cylinder evaporator can be utilized to cool the cylinder
contents.
Thus, the present invention, by being able to build a cooling reserve and by
obtaining
better cooling efficiency from the freeze cylinder evaporators, is able to
accomplish more
cooling with the same sized refrigeration system found in a comparable prior
art machine
or can accomplish the same amount of cooling with a smaller refrigeration
system.
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In one preferred embodiment of the present invention, a freeze cylinder is
used having a
closed end and an open end. Around the cylinder adjacent the closed end a
brushless DC
stator is placed. The stator is connected to a DC power supply (or inverter).
An
evaporator is coiled around substantially the remainder of the exterior of the
cylinder and
connected to a mechanical refrigeration system. A spacer plate holds a bearing
centrally
thereof and is retained within the cylinder against the closed end thereof. A
rotor is
positioned in the cylinder adjacent the spacer plate. The rotor consists of
metal ring
around the perimeter of which are secured eight permanent magnets. The magnets
are
equidistantly spaced and alternate as to their polarity. The magnets and disk
are encased
in a food grade plastic creating a rotor disk having a central hole. A scraper
extends
along the axis of the cylinder and includes a central rod end that extends
through the rotor
and into the bearing of the spacer disk. The scraper includes a skirt portion
around the
rod end for securing to the rotor. The open end of the cylinder is sealed in
the
conventional manner with a plate which includes a valve for dispensing
beverage from
the interior volume of the cylinder and a rotative support for the opposite
end of the
scraper central rod . A delivery line provides for delivery of the beverage
from a source
thereof into the cylinder through a beverage inlet fitting.
In operation, it can be understood that the stator and rotor constitute a
brushless DC three
phase motor that is operated by the power supply to rotate the scraper within
the cylinder.
Those of skill will readily appreciate that no dynamic seal is needed as no
rod end of the
scraper is required to extend out of the cylinder for mechanical connection to
a drive
motor. In addition, prior art machines require a gear case between the actual
drive motor
and the scraper rod. This mechanism is also eliminated by the present
invention.
Accordingly, the present invention provides for a machine that requires less
in the way of
service calls and that is thereby less expensive to operate. Encasing the
rotor in a food
grade plastic permits that portion of the motor to reside within the cylinder
thereby
making the motor an integral part of the cylinder.
CA 02255786 1999-04-O1
In a further embodiment of the present invention, a freeze cylinder is used
that also has a
closed end and an open end. A conventional motor and gear drive are used,
however the
gear drive is adapted to rotate a circular magnetic drive plate. The plate
includes a
plurality of permanent magnets of alternating polarity secured on one surface
thereof in a
circular arrangement. This external magnetic drive plate is positioned so that
the
magnetic surface thereof faces and is closely adjacent the exterior surface of
the cylinder
closed end. Within the cylinder a similar circular magnetic ring is rotatively
mounted
therein within an annular groove of a stainless steel disk. This internal disk
is secured to
a rod end of a scraper and the magnetic face of the magnetic ring faces the
internal
surface of the cylinder end and is positioned closely adjacent thereto. A
round plastic
collar is secured over the annular groove for sealing the magnetic ring
therein.
In operation, the motor is used to rotate the external magnetic drive plate.
The external
drive plate is magnetically coupled to the magnetic ring of the internal
driven disk
wherein rotation is imparted to the scraper. Thus, this embodiment of the
present
invention provides for a magnetic drive of the scraper wherein no dynamic seal
is
required. The internal magnetic ring is sealed from contact with the food
product by the
food compatible stainless steel and plastic collar, thereby permitting the use
of that
essential magnetic drive component within the cylinder.
DESCRIPTION OF THE DRAWINGS:
A better and further understanding of the structure, function and the objects
and
advantages of the present invention can be had by reference to the following
detailed
description which refers to the following figures, wherein:
Fig. 1 shows a perspective view of a frozen food product dispensing machine.
Fig. 2 shows an exploded view of a frozen food product cylinder assembly in
conjunction with a first drive mechanism of the present invention.
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CA 02255786 1999-04-O1
Fig. 3 shows a plan view of the frozen food product cylinder assembly
including the
first drive mechanism of the present invention.
Fig. 4 shows a cross-sectional view along lines 4-4 of Fig. 3.
Fig. 5 shows a cross-sectional view along lines 5-5 of Fig. 2.
Fig. 6 shows an electrical schematic for the first drive mechanism.
Fig. 7 shows a cross-sectional view of a frozen food product cylinder assembly
including a second drive mechanism of the present invention.
Fig. 8 shows a surface plan view of a magnetic drive disk of the present
invention.
Fig. 9 shows a cross-sectional view along lines 9-9 of Fig. 7
Fig. 10 shows a perspective view of a frozen food product dispensing machine.
Fig. 11 shows an enlarged cross-sectional view of the driven disk.
Fig. 12 shows a perspective view of the present invention.
Fig. 13 shows a further perspective view of the present invention.
Fig. 14 shows an perspective view of the present invention having the panels
removed
therefrom.
Fig. 15 shows a partial cut away view of the water bath tank.
Fig. 16 shows a cross-sectional plan view of a carbonator/blending bottle.
Fig. 17 shows a top plan view of the a carbonator/blending bottle.
Fig. 18 shows a schematic diagram of the refrigeration system.
Fig. 19 shows a schematic diagram of the fluid beverage system.
Fig. 20 shows a schematic diagram of the electronic control.
Fig. 21 shows a perspective view of the dual ice bank control sensor.
Fig. 22 shows a end plan view along lines 21-21 of Fig. 20.
Fig. 23 shows a flow diagram of the viscosity monitoring control logic.
Fig. 24 shows a flow diagram of the viscosity control logic
Fig. 25 shows a flow diagram of the ice bank forming control logic.
Fig. 26 shows a flow diagram of the expansion valve control logic
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DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT:
A frozen food product making and dispensing machine is seen in Fig. l, and
generally
referred to by the number 10. Machine 10 is illustrative of the type wherein
the present
invention can be applied. As seen by also referring to Fig.'s 2-4, a stainless
steel cylinder
12 includes a cylindrical wall 14 and a stainless steel plate 16 welded to one
end thereof
forming a closed end surface and defining a cylinder interior 18. A three
phase stator 20
includes a ring portion 22 made of multiple lamination layers 22a to which
three
electrical windings 23 are wound and braided there around. Stator 20 is
positioned on the
end of cylinder 12 adjacent end wall 16 with cylinder wall 14 extending
through the
center thereof.
A plastic spacer disk 24 is located within cylinder 12 and is positioned
against end wall
16. Disk 24 is made of a suitable food grade plastic and includes a bearing 26
mounted
centrally thereof. As understood by also refernng to Fig. 5, a rotor 30
includes a metal
tube ring section 32 having eight permanent magnets 34 secured equidistantly
around a
perimeter thereof wherein the North and South polarities thereof alternate.
Ring 32 and
magnets 34 are encased in a food grade plastic 35, such as Delrin~, molded
there around
and leaving a central shaft hole 36.
A scraper mechanism 40, also made of a suitable food grade plastic, includes a
central
shaft 42 having a plurality of mixing rods 44 and scraper blade supports 46
extending
therefrom. A pair of scraper blades 48 are mounted on supports 46 wherein
holes 50
thereof receive pin portions 52 of supports 46. Shaft end portion 54 extends
through hole
36 and is received in hole 28 of bearing 26. Shaft 42 also includes an
attachment skirt 56
for securing thereof to rotor disk 30. An opposite end 58 of shaft 42 is
received in a short
support section 60 integral with extending from a plastic end cover 62. Cover
62
includes an o-ring 64 extending around a cylinder inserting portion 66
thereof. Cover 62
is secured to cylinder 12 by a plurality of bolts 67a and nuts 67b. Flange 68,
as with plate
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16, is also made of stainless steel and welded to cylinder 12. As is known in
the art,
cover 62 includes a hole 70 for receiving a dispensing valve 72.
As is understood by those of skill, an evaporator coil 74 extends around the
exterior of
cylinder 12 and includes an inlet fitting 74a and an outlet fitting 74b.
Fittings 74a and 74b
are connected to high pressure line 76 and low pressure line 78 respectively
of a
mechanical refrigeration system including a compressor 80 and a condenser 82.
Insulation 84 extends around cylinder 12 and evaporator 74. A beverage inlet
line 86 is
connected to a cylinder inlet fitting 88 and a beverage reservoir or mixing
tank 90. A pair
of cylinders 12 can be secured within the housing of dispenser 10 and
supported therein
by a framework 92 thereof.
As seen in the schematic of Fig. 6, a power supply 94 includes an inverter 96
for
converting 220VAC to a three phase DC current. This three phase current is
connected to
the three winding 23 of stator 20. Thus, those of skill will understand that
stator 20 and
rotor 30 comprise a DC motor. In operation, therefore, the three phase current
induces
movement of rotor 30 which, in turn, rotates scraper mechanism or assembly 40.
Thus,
with a beverage, for example, delivered within cylinder 12 through line 86 and
cooling
thereof by evaporator 74 and its associated refrigeration system, frozen
beverage can be
produced by scraping thereof from the interior surface of cylinder 12. The use
of a rotor
around which a food grade plastic has been molded permits that part of the DC
drive
motor to be internal of the cylinder and in contact with the food product. In
general, all
the components of the present invention are made of or coated with a suitable
food grade
material. Thus, the present invention comprises a drive mechanism for a frozen
food
product machine utilizing an internally scraped cylinder wherein the drive
motor
therefore is an integral part of the cylinder assembly. As a result, no
dynamic seal or
external shaft bearing is needed for the scraper mechanism. Thus, the
traditional external
motor, dynamic seal, external shaft bearing and transmission can be
eliminated.
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CA 02255786 1999-04-O1
In one example of the integral DC motor drive embodiment of the present
invention, the
drive motor is used in a cylinder that is approximately 15 inches long with a
diameter of
approximately 4.5 inches. The drive motor in such an application is designed
to produce
a torque of approximately 110 inch/lbs. at 100 RPM's.
In a second embodiment of the present invention, as seen in Fig.'s 7-9, a
cylinder 100 has
a cylinder wall 102 and an end plate 104 defining a cylinder end surface 106.
An AC
motor 108 is secured to a transmission 110 which is in turn secured to a
plastic collar 112
attached to plate 104. Transmission 110 includes a drive shaft 114 to which is
attached a
magnetic drive disk 116. As seen in Fig. 8, disk 116 includes six permanent
magnets 118
secured thereto around a perimeter of one side or face thereof wherein the
North and
South polarities thereof alternate. Magnets 118 are positioned to face and be
held closely
adjacent end surface 106.
Within cylinder 100 a food grade plastic spacer 120 is positioned against the
interior
surface of end wall 106. Spacer 120 includes a central bearing 122 and
includes an
annular wall portion 124 defining a disk retaining space 126. A food grade
plastic collar
128 is received in stainless steel bearing 122 and on one end thereof has a
driven
magnetic disk 130 secured thereto. As seen by also refernng to Fig. , a
stainless steel
disk 130 includes a plurality of permanent magnets 131 arranged on a metal
ring 132.
Ring 132 is secured to disk 130 within an annular groove 134 thereof as
defined by walls
135. A plastic collar or ring cover ring 136 is secured to walls 135 around a
top
perimeter thereof for sealably enclosing magnets 131 and ring 132 within
annular groove
134. Magnets 131 of disk 130 are positioned to face and lie closely adjacent
the interior
surface of end wall 106.
As with the first drive embodiment described above, the second drive
embodiment also
includes a scraper mechanism 40 having a central shaft 42 having a plurality
of mixing
rods 44 and scraper blade supports 46 extending therefrom. A pair of scraper
blades 48
are mounted on supports 46 wherein holes 50 thereof receive pin portions 52 of
supports
CA 02255786 1999-04-O1
46. A shaft end portion 140 is shaped as seen in Fig. 9, to provide for
driving receiving
thereof in a similarly shaped bore 142 of collar 128. As with the previously
described
embodiment, an opposite end 144 of shaft 42 is received in support 60
extending from
plastic end cover 62. Flange 68, as with plate 104, is also made of stainless
steel and
welded to cylinder 100.
As with the previously described DC motor embodiment, cylinder 100 includes an
evaporator coil 74 extending there around that includes an inlet fitting 74a,
an outlet
fitting 74b and a food product/beverage inlet 88 for connection as stated
above.
Insulation 84 also extends around cylinder 100 and evaporator 74. A pair of
cylinders
100 can be secured within the housing of dispenser 10 and supported therein by
a
framework 92 thereof.
In operation, motor 108 operates through transmission 110 to rotate magnetic
disk 116.
Due to the magnetic coupling between disk 116 and 130 as they face each other
on
opposite sides of end wall 106, rotation of disk 116 results in the rotation
of disk 130, and
hence, rotation of scraper mechanism or assembly 40. Thus, with beverage or
food
product delivered within cylinder 100 through line 86 and cooling thereof by
evaporator
74 and its associated refrigeration system, frozen beverage can be produced by
scraping
thereof from the interior surface of cylinder 100. This magnetic drive
embodiment, as
with the DC motor embodiment herein, eliminates the need for a dynamic seal
and an
external bearing with respect to the shaft 42 of the scraper mechanism 40.
Also, plate
having an annular groove for receiving the magnets and ring wherein those
components
are sealed therein by a food grade plastic ring, permit the driven disk 130 to
be in contact
with food product, i.e. permits a magnetic drive approach or mechanism that is
food
compatible.
A further embodiment of the present invention is seen in Fig.'s 12 and 13 and
generally
referred to by the numeral 200. Machine 200 has an outer housing having
removable
panels, including side panels 201, a top panel 202 and a display door 203
having a
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CA 02255786 2000-11-20
transparency window 204. Panels 201 and 202 include louvers 205 and an air
flow
grate 206, respectively. A plurality of light fixtures 208 are secured to door
203, and
are used for back lighting a transparency 210. Door 203 is hinged to a front
surface of
machine 200, and as seen in Fig. 13, can be swung to an open position for
facilitating
access to fixtures 208 and to user interface 212.
As seen by also referring to Fig. 14, machine 200 includes a framework 213 for
supporting various internal components as well as the various portions of the
exterior
housing including housing panels 201 and 202, and access door 203. A pair of
freeze
cylinder assemblies 214 are held within separate insulated housings 216. Both
cylinder
assemblies 214 are of the type disclosed above in Figs. 2-6 herein and have DC
drive
motors 217 as also shown and described therein. However, unlike dispenser 10,
embodiment 200 includes a water bath tank 218. Tank 218 includes sides 219 for
retaining a volume of water therein. As seen by also referring to Fig. 15,
tank 218
includes an ice bank forming evaporator 220. Evaporator 220 is held therein by
support means 222 and positioned thereby adjacent three of the four interior
surfaces
of sides 219.
A pair of specialized carbonator/blender bottles 224 are retained in tank 218.
Bottles
224 are seen in greater detail in Figs. 16 and 7 and are essentially the same
as the
carbonator disclosed in U.S. Patent No. 5,792,391 issued on August 11, 1998.
Bottles
224 each include a cylindrical stainless steel body 226 having a bottom end
228 and a
top open end 230. A plastic disk 232 is sized to flt within open end 230 and
sealed
there against by an o-ring 234. Disk 232 is releasably retained in open end
230 by
means of a wire spring or clip 238. Clip 238 can be grasped by ends 238a
thereof to
remove from or insert into slots 240, cut through cylinder 226, through which
radiussed corners 238b are inserted. Disk top surface 242 is designed to
cooperate
with clip 238 to minimize any accidental disengagement thereof with disk 232.
In
addition, disk 232 includes a fluid inlet 244, a gas inlet 246 for receiving
pressurized
carbon dioxide gas and a fluid outlet 248. Disk 232 also includes a safety
release
pressure valve 250 and a liquid level sensor 252.
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Sensor 252 includes a rod 254 that is positioned within bottle 224 having a
movable float
256 free to slide there along. Rod 254 includes one or more magnetically
actuated
switches 258 therein and along the length thereof, and float 256 includes a
magnet 260.
As is understood in the art sensor 252 operates whereby float 256 is carried
by the level
of liquid within 224. As magnet 258 moves adjacent one of the switches 258
turning it
on, then a level can be indicated. Inlet 244 is fluidly connected to a J-tube
262, and outlet
248 is fluidly connected to a tube 264 extending to a point adjacent bottle
end 228.
Water bath tank 218 also includes a two serpentine coils of heat exchange
stainless steel
tubing 262 positioned together and adj acent a fourth or remaining interior
surface side
against which evaporator 220 is not positioned. An agitator motor 264 is
secured to a top
cover panel 266 and includes a shaft and attached agitator blade, not shown,
for agitating
the water within bath 218.
As understood by also refernng to Fig. 18, the refrigeration system used in
machine 200
includes a refrigeration compressor 270 connected by refrigerant high pressure
and low
pressure lines 271a and 271b, respectively, to a condenser 272. Each cylinder
assembly
214 includes an evaporator coil 274 and each evaporator coil has associated
there with an
electronically pulsed expansion valve 276 and a hot gas defrost valve 278.
Also, each
coil 276 includes an inlet temperature sensor 277a and an outlet temperature
sensor 277b.
The ice bank forming evaporator 220 is also connected to compressor 270 by
high and
low pressure lines 271a and 271b. Evaporator 220 also has refrigerant metered
therein by
an electronically pulsed expansion valve 280. Evaporator 220 also includes an
inlet
temperature sensor 282 and an outlet temperature sensor 284.
An ice bank 286 forms on evaporator 220 and, as further understood by refernng
to Fig.'s
21 and 22, the size thereof is regulated by a pair of ice bank sensors 288a
and 288b.
Sensors 288a and 288b each include a housing 290 wherein a pair of wire probes
291
extend. Probes 291 are connected to wires 292 that provide connection to the
control of
the present invention, further described below. Each housing 290 is secured to
an
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attachment plate 293. Sensor 288a is secured to a first level surface 293a of
plate 293 and
sensor 288b is secured to a second outer level surface 293b thereof. Thus, a
differential
distance D, as indicated by the dashed lines of Fig. 21, is created between
the probes 291
of each of the sensors 288a and 288b. A flange 294 and hook 295 provide for
attachment
of plate 293 to a suitable support means within ice bath 218 at a suitable
distance from
evaporator 220.
A schematic of the beverage fluid delivering system used in the present
invention can be
understood by refernng to Fig. 19. A seen therein, an inlet water line 300 is
connected to
a source of potable water for delivering the water, first to a T-fitting 302
and then to a
brixing or ratioing valve 304. A second line 306 extends from fitting 302 to a
float
operated valve 308 positioned within water bath tank 218. A third line 310 is
connected
to a source of beverage syrup, such as a bag-in-box 312. Line 310 includes a
fluid flow
sensor 314 and is fluidly connected to a further brixing valve 316. Sensor 314
is of the
piston fluid contact type as, for example, model FS-3, as manufactured by Gems
Sensors,
of Plainville, Connecticut. Valves 304 and 316 provide for mixing the water
and syrup at
a ratio of typically 5 to 1 respectively. The fluid components flow to a Y-
fitting 318 and
are mixed together. A pump 320 pumps the properly ratioed, but as yet
noncarbonated
beverage, to a test valve 322 and from there to one of the heat exchange
serpentine coils
located in tank 218. Valve 322 normally directs the beverage to a coil 262,
but can be
manually operated to divert and deliver a test sample of the beverage along
line 324 to an
outlet point. In this manner the beverage can be easily tested to check for
the proper
ratioing thereof by valves 304 and 316. The beverage flows from a coil 262 to
inlet 244
of the associated blender/carbonator bottle 224. A pressurized source of
carbon dioxide
gas 326 provides carbon dioxide first to a valve 328. Valve 328 provides for
diverting
carbon dioxide gas to bag-in-box 312 in the example where a carbon dioxide
pump 327 is
used to move syrup therefrom. Those of skill will realize that other means,
such as
electric pumps can be used to pump the syrup whereby valve 328 would not be
required.
Or, carbon dioxide gas can be used to propel the syrup from a rigid stainless
syrup tank.
Regulator valves 330a and 330b provide the carbon dioxide at a desired
pressure to the
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gas inlets 246 of each blender/carbonator 224 positioned in tank 218. It will
be
appreciated that Fig. 18 shows a schematic of one of the beverage fluid
systems, there
being one for each cylinder assembly 214.. Thus, in a machine 200 having two
cylinders
214, there are two brixing valves 304,two brixing valves 316, two coils 262,
tow pumps
320, two flow sensors 314, and two carbonator/blenders 224. The outlets of
each
blender/carbonator 224 are connected to outlet lines 332 that are connected
first to
manual valves 234 and then to inlets 236 of each of the cylinders 214. Valves
234
provide for manually stopping the flow of carbonated beverage to cylinders
214,
primarily for the purpose of facilitating servicing thereof.
Sensors 314 provide a major advantage in that they are able to sense when the
syrup has
sun out whether the syrup is delivered from a bag-in-box or from a stainless
tank. Prior
art machines required that there be two sensor systems, one for either syrup
containing
source. A pressure sensor was required for the bag-in-box as, when the bag
became
empty, there would be no pressure, and that would indicate a sold out
condition.
However, if a tank was used the carbon dioxide gas used to propel the syrup
would
indicate to the pressure sensor that syrup was present, when in fact, it was
not. Thus, a
tank syrup reservoir required a float sensor that would only be affected by
actual liquid
syrup. Therefore, sensor 314 eliminates having redundant systems and the
associated
cost and complexity thereof.
It can be appreciated that the present invention provides for the cooling of a
volume of
beverage within coils 262 prior to introduction thereof into each
blender/carbonator 224.
Thus, the beverage will have reached a temperature of approximately 36 degrees
Fahrenheit prior to the introduction thereof into a corresponding container
224. In
addition, each blender/carbonator is also held at the same temperature being
immersed in
the cold water bath. Therefore, the carbonation of the beverage that occurs
therein can
reach a desired level of saturation at much lower carbon dioxide gas pressures
than if the
mixing were occurnng in a bottle held at a much warmer room ambient
temperature. In
addition, the present invention has a much greater beverage production
capacity, as an ice
CA 02255786 1999-04-O1
bank presents a large cooling reserve that would otherwise not be available
unless an
exceedingly large refrigeration system is used. Thus, as the beverage is
presented to the
freeze cylinder at a very low temperature, the cooling required of the freeze
cylinder
evaporators is much lower so that overall, the present invention works much
more
efficiently than do comparable prior art machines that produce semi-frozen
beverages or
food products from beverage delivered to the cylinders at ambient
temperatures.
As seen in Fig. 20, the present invention uses a distributed electronic
control having a
product delivery control board 340 for the control of each cylinder 214. A
main logic
board 342 is connected to each control board 340, and there is one inverter
board 344 for
each of the two cylinders 214. The boards communicate as is generally
indicated by the
arrows of Fig. 19. Main board 342 receives inputs from the user interface 212,
and from
each of the product delivery board (340) on the system, as well from the COz
pressure
sensor, an H20 pressure sensor, high/low line voltage, ice bank thickness
(min), ice bank
thickness (max.), ice bank evaporator input temperature and ice bank
evaporator output
temperature. Main board 342 controls the operation of compressor 27- on/off,
ice bank
agitator motor and ice bank pulse valve. Each product delivery board receives
inputs
from its associated syrup flow sensor 314, level sensor 252, evaporator input
temperature
sensor, evaporator output temperture sensor, product viscosity sensor and
beater motor
error, and controls the operation of its associated beater motor on/off,
defrost valve
on/off, pulse valve on/off, syrup valve on/off, Hz0 valve on/off, disp. Valve
lockout,
product status light and blendonator pump 320. The inverter board 344 provides
for
inverting the 240VAC supplied current to the 340VDC current used by motors
217. In
addition, it senses the current draw being placed on each motor 217 and runs
them at a
constant 120 revolutions per minute (RPM).
A distributed control is used to better accommodate machines having more than
two
cylinders 214. Thus, the main board 342 can be designed to work with more than
two
product delivery boards. In this manner, a cost saving can be had as opposed
to having a
main control board having to be designed specifically for each machine having
a
16
CA 02255786 1999-04-O1
particular number of cylinders. The main board receives the commands from the
operator
interface, and distributes this information to the appropriate board. For
instance, if the
operator wants to turn on cylinder #1, the main board will send the "on"
command to the
product delivery board on cylinder #1. The PDB will then tell the inverter
board to apply
power to stator #1, as well as request the compressor to come on and begin
pulsing the
pulse valve for cylinder #1.
A better understanding of the control logic utilized by the control of the
present invention
to monitor the viscosity of the beverage, control the viscosity of the
beverage and to
regulate the ice bank can be had by refernng to the flow diagrams thereof
shown in Fig.'s
23-26. Viscosity is monitored as a function of the current draw of the DC
drive motor for
the particular cylinder. In addition, each motor 217, as stated above, is
controlled to
operate at a constant 120 RPM rate. Thus, the more viscous the beverage the
greater load
and current draw on the motor 217 to maintain the set point rotational speed.
Since the
motors 217 are directly driving the cylinder scraper mechanisms, and the RPM's
are kept
constant, there exists a very direct correlation between the current draw of
the motors and
the viscosity of the food product. Each product delivery board has look up
tables that
correlate the current draw to an arbitrary viscosity number scale, which scale
is utilized
by each board to indicate a level of viscosity of the beverage within the
cylinder. As seen
in Fig. 23, a start point is indicated by block 350. The viscosity is
monitored by each
board 340,wherein at block 351 it is determined if the viscosity is below a
preset
viscosity minimum. If the viscosity is below that minimum, and it has been
below that
minimum for greater than one second, block 352, then at block 354, it is
determined if
compressor 270 is on. If compressor 270 is on, then the viscosity is
controlled at block
356. A more detailed description of the viscosity control is contained below
with
reference to Fig. 24. If compressor 270 is not on, then the control inquires
if it has been
off for more than two minutes, block 358. If it has, then compressor 270 is
turned on at
block 360 and viscosity is controlled at block 356. At block 361, it is
determined if the
desired viscosity has attained a predetermined desired level. If it has, the
compressor is
turned off at block 362 and the control goes to return at block 364 and
monitors the
17
CA 02255786 1999-04-O1
viscosity. If at blocks 351, 352 or358 it is determined, respectively, that
the viscosity is
not below viscosity minimum or the viscosity minimum was not maintained for
more
than one second or that the compressor has been off for less than two minutes,
then the
control, at block 366, determines if the float sensor 252 of the associated
bottle 224 has
been activated to signal for more beverage to be pumped therein, i.e. has
beverage been
drawn from the associated cylinder whereby further beverage must be replaced
therein,
and in its associated carbonator/blender 224. If the float has been activated,
then further
beverage is added to the cylinder by control of pump 320 and operation of
valves 304 and
316. The control then inquires, at block 368, if the compressor is on, and
turns the
compressor on as needed or proceed directly to viscosity control, block 356.
If the sensor
252 has not been activated to deliver more beverage within its associated
bottle 224,
block 366, then the control determines if 5 minutes has elapsed since the last
refrigeration
cycle, block 370. If less than the 5 minutes has elapsed, the control goes to
return, block
372 where viscosity is monitored. If more than 5 minutes have elapsed since
the last
operation of the compressor, the control then inquires, at block 368, if the
compressor is
on, and turns the compressor on as needed, block 360, or proceeds directly to
viscosity
control, block 356.
The viscosity control of the present invention can be better understood in
terms of the
flow diagram of Fig. 24. At the start block 380 the control moves to blocks
381 and 382,
where the board determines the inlet and outlet temperatures, respectively, of
the
particular evaporator coil 274, and at block 384, measures the barrel
viscosity. At block
386 it is determined if the viscosity is greater than a pre-selected viscosity
maximum. If
it is, the control queries if the particular coil 274 is in the "top off
mode", block 388. If
not, the top off mode is begun at block 390. The top off mode is a sequence
that permits
a relatively accurate determination of the beverage viscosity. Thus, at block
392 a 3
second timer is started during which the associated pulse valve 276 is closed,
block 393.
Further refrigeration is stopped for this time period, however the scraper
mechanism
continues to turn. At block 394 pulse valve 280 is operated to provide for
building of the
ice bank. A further understanding of the control of the ice bank will be had
below in
18
CA 02255786 1999-04-O1
reference to Fig. 25. At block 396, the maximum viscosity sensed during the
top off
period is recorded. If the 3 second timer has timed out, block 398, then the
control
determines if the difference between the present viscosity and the maximum
viscosity
currently sensed during top off is lesser or greater than a pre-selected
viscosity delta or
difference, block 400. The delta is contained in a look-up table and is an
experimentally
derived number. If the delta is not exceeded, this means that the viscosity of
the beverage
is at the desired level and refrigeration of the cylinder can be stopped,
block 402, and the
control can go to return 404. If the measured delta is too large, i.e. in
excess of the preset
delta, this indicates that the beverage is not viscous enough. Then the
control goes to
block 406 ending top off and continuing refrigeration and goes to return 404.
Ice can not
be built on evaporator 220 during refrigeration of either coil 274. Only when
both
cylinders are satisfied and/or are otherwise not being cooled. Thus, if the
other cylinder
evaporator 274 is being cooled, cooling of evaporator 220 is not permitted.
Therefore,
ice can be formed during top off if the other coil 274 is not being cooled or
if both are in
top off. As a consequence thereof, if top off has ended as the delta was too
large, block
400, further cylinder cooling is required and cooling of evaporator 220 is
stopped, if one
or both cylinders 214 are in a refrigeration sequence. At block 386, if the
viscosity is
below the preset viscosity maximum, then at block 408 the temperature of the
particular
inlet~of the associated coil 274, as measured by sensor 277a, is determined.
If that
temperture is greater than 40 degrees Fahrenheit, then a
proportional/integral/differential
"PID" calculation is made to control the temperature down to 40 °F,
block 410. As is
understood in the control art, PID control generally follows the equation PID
=E~(Kp) +
(EP" Ep2...E°)K;+ ((d)E/(d)t)I~. where Ec is the current error, Kp is a
proportional
proportionality constant, Ep,...represent previous error values, K; is the
integral
proportionality constant, (d)E/(d)t is the rate of change of the error and Ka
is the
associated differential proportionality constant. The value (EP" EPZ...E~)
represents an
equation, such as the averaging of the E values, that, multiplied by K;
represents the
portion of the PID valve that is based on the size the error over time. The
E~(Kp) value
represents the portion of the PID valve that is based on the size of the
currently measured
error. All three variables can be used produce a very accurate understanding
of how a
19
CA 02255786 1999-04-O1
particular target point is being approached. In the present invention, PID
control is used
to control to a 40 degree F set point with a high degree of accuracy. The
particular pulse
valve 276 is operated accordingly, block 412, as per the PID output. If at
block 408 the
temperature of the inlet is less than 40 degrees F, then it is determined if
the outlet
temperature, as determined by sensor 277b, is greater than 46 degrees F, block
414. If
that temperature is greater than 46 degree F, then the logic control returns
to blocks 410
and 412 and controls the temperature of the inlet to 40 degrees F. Thus, the
control is
first seeking to establish a delta T of six degrees between the coil 274 inlet
and outlet
temperatures at a particular starting point where the inlet temperature is 40
degree F and
an outlet temperature is 46 degrees. When that is accomplished, then, at block
416, the
PID control can be used to simply control the delta T to 6 degrees F whereby
the inlet and
outlet temperatures can fall below 40 and 46 respectively, as long as the
delta T of 6
degrees between them is accurately maintained.
A better understanding of the ice bank control herein can be has with
reference to Fig. 25.
At the start point 420, the control then starts a 30 second ice measure timer,
block 421.
During that 30 second interval ice sensors 288b and 288a are measured,
respectively,
blocks 422 and 423. After the 30 second timer has timed out, block 424, the
control
determines if either cylinder 214 is calling for refrigeration, block 425. If
either cylinder
is calling for refrigeration then it is determined if the compressor 270 is
running, block
426. The compressor is then turned on, block 427, or the control goes directly
to block
428. At block 428 it is determined if either cylinder is in a normal operate
mode, i.e. not
in top off and requiring refrigeration. If either cylinder is in a normal
operating mode,
then no refrigeration of the ice bank can occur and the control goes to
return, block 429.
If one or both are not in normal mode, i.e. in top off mode, then the
particular pulse valve
276 is pulsed at the top off rate, block 430 and the control goes to return
431 the rate that
is determined to maintain a 20 degree F temp. If, at block 425, neither
cylinder 214 is
calling for refrigeration, then ice bank sensor 288b is polled to determine if
ice is present,
block 432. If sensor 288b senses ice, then no more building of ice is
desirable so, if the
compressor is running, block 434, it is turned off, block 435 and valve 280 is
opened for
CA 02255786 1999-04-O1
seconds to equalize pressure, block 436, and the control goes to return, 438.
If sensor
288b does not sense ice, then at block 440, the control looks at sensor 288a
to see if it
senses ice. If sensor 288a so indicates, then the control follows blocks 434,
435, 436 and
438. If sensor 288a does not sense ice, then ice can and should be added to
the ice bank,
it having eroded to a point that a greater cooling reserve is desirable. Thus,
at block 444,
if the compressor is running, pulse valve 280 is operated to cool evaporator
220 and build
ice thereon, block 445. If the compressor is not running, it is turned on,
block 446. Pulse
valve 280 is operated as per the flow diagram valve control loop delineated in
Fig. 26
below.
As can be understood by refernng to Fig. 26, at a start point 450, the control
measures
evaporator 220 inlet temperature using sensor 282a, block 452 and then
measures the
outlet temperature thereof using outlet sensor 282b, block 454. The delta T of
evaporator
220 is controlled in substantially the same manner as previously described for
the
cylinders 214. Thus, the inlet temperature is first sensed, block 456, and
moved down
using a PID control, block 458, and a valve pulse timer as per that PID
calculation, block
460, to a preset temperature of 20 degrees F. Once that value is attained, the
control goes
to return, block 462. If the inlet temperature is less than 20, then the
control determines if
the outlet temperature is greater than 40 degrees, block 464. If it is then
the control
returns to blocks 458 and 460 to move the inlet temperature to 20 degrees F.
Once the
inlet temperature is equal to 20 degrees F and the outlet temperature is equal
to -40
degrees F, then at block 464, the control then moves to block 466. At block
466 a PID
control is utilized to maintain a delta T of 20 degrees F. The pulse valve 280
is set
accordingly, block 468, and the control goes to return, block 270.
Those of skill will understand that the present invention provides for the
production of a
semi-frozen food product in a manner that maximizes the efficiency of
operation of the
refrigeration system thereof. The life of the compressor is extended as
refrigerant gas can
be alternately directed to either of the cylinder evaporators 274 or the ice
bank evaporator
220. In particular, the two ice bank sensors provide for an incremental area
between an
21
CA 02255786 1999-04-O1
ice bank maximum size and an ice bank minimum size where the ice bank can be
grown
to prevent the compressor from running and building pressure after both the
valves 276
are closed. In this manner the compressor is not short cycled or presented
with damaging
high pressures when an expansion valve is closed. Since the erosion of the ice
bank
generally occurs at a faster rate than it is built up, it is contemplated that
there will be
very few or no occasions where the refrigerant can not be diverted to
evaporator 220 so as
to protect the compressor.
Furthermore, as an ice bank is used, a large cooling reserve can be built up
during the
times that neither cylinder 214 is calling for refrigeration, such as when the
beverage
therein is of sufficient viscosity, or where the cylinders have been shut down
entirely
during a "sleep mode", well known in the art, where no drinks will be
dispensed. Also,
as the PID control permits a much smaller delta T to be maintained in a safe
manner,
better efficiency of cooling is obtained from evaporators 274 and evaporator
220.
Dispenser 200 therefore has a substantial advantage over comparable prior art
machines
in terms of refrigeration system design parameters. Dispenser 200 can use a
much
smaller compressor to do the work of a larger compressor in a prior art
machine, or obtain
more cooling from the same sized system.
As seen by again refernng to Fig. 3, framework 213 defines three areas 500,
542 and 504.
Top area S00 will be understood to retain water bath 218, condenser 272 and
compressor
270. Middle area 502 retains cylinder packs 216, and the expansion valves 276
and 280
and the defrost valves 278. Lower section 504 includes beverage pumps 320 and
ratio
valves 304 and 316. As is known in the art, defrost valves 278 serve to
provide hot gas
defrost of each cylinder 214. Such defrost is periodically required to remove
large
particles of ice that can periodically form within a cylinder. A filter grate,
not shown, is
secured to condenser 272 on the exterior side of beverage machine 200 opposite
from the
fan 273 thereof.
22
