Note: Descriptions are shown in the official language in which they were submitted.
~ CLEAR CUBE ICE MAKER 2 1 1 4 6 7 1
Field of the Invention
This invention relates to ice makers and, more
particularly, to a clear cube ice maker for use in a
refrigeration apparatus.
Background of the Invention
Commercial ice makers have long been available
for producing clear ice. A typical such ice maker is
illustrated in Barnard U.S. Patent No. 4,009,595 owned by
the assignee hereof. Such an ice maker is intended for
producing ample quantities of ice bodies and is not readily
adaptable for use in a domestic refrigerator. Moreover,
such an ice maker differs from those in domestic
refrigerators in that it does not utilize a below-freezing
compartment for maintaining the ice bodies in a frozen
condition.
Ice makers for domestic refrigerators may produce
ice bodies that are cloudy. This results from the ice
bodies being formed in a tray wherein gases are trapped in
solution in the freezing water. The commercial type ice
makers discussed above produce clear ice because freezing
proceeds from a cold surface into a water bath so that the
freezing ice-water interfaces a surface from which gases
coming out of solution can escape.
Apparatus have been disclosed for forming clear
cube ice bodies in which a container holding a bath of
water is moved in a cyclical manner to be proximate and
remote from chilled fingers on which ice bodies are formed.
Such an ice maker is not adapted to be placed in a freezer
as the bath of water in the container would freeze,
rendering the device inoperable. Moreover, such a device
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relies on mechanical, fixed structure which does not lend
the device to be adaptable to varying refrigeration
conditions.
Because the storage bin in a domestic
refrigerator is contained in the freezer compartment, ice
bodies are stored at below-freezing temperature. In order
to prevent icing together of separate ice bodies it is
necessary that the ice bodies must have dry surfaces when
placed into the storage container.
The present invention is intended to overcome the
problems discussed above.
SummarY of the Invention
In accordànce with the invention there is
disclosed a control for a clear cube ice maker.
Broadly, there is disclosed herein an ice maker
for making clear ice bodies comprising a support arranged
to have an ice body formed thereon and means for
refrigerating the support to a below freezing temperature.
A container is adapted to hold a body of water. Means are
provided for moving the container to move liquid water
contained therein uniformly about the support suitable to
cause a clear, substantially symmetrical ice body to build
up outwardly on the refrigerated support, comprising a tray
supporting the container, the tray including support pins
received in a track defining a path of movement of the
tray, and a drive controlling movement of the tray. Means
are provided for heating the container to prevent freezing
of water container therein, and means for causing
harvesting of the ice body from the support.
It is a feature of the invention that the pins
comprise conductive pins and the heating means comprises an
electrical heater connected to the pins.
It is another feature of the invention to provide
electrical power terminals positioned at select locations
of the tracks to control operation of the heating means
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incident to the tray being at a select position at the
select location.
It is another feature of the invention that the
heating means includes a control for operating the heating
means only during a time when the moving means moves the
container to move liquid water about the support.
It is another feature of the invention to provide
storage means for causing repositioning of the container to
withdraw the water in the container from adjacent the
support prior to harvesting of the ice body.
It is yet another feature of the invention that
the heating means includes a control for disabling the
heating means during a time period when the storage means
repositions the container to withdraw water from adjacent
the support.
In accordance with another aspect of the
invention there is disclosed an ice maker comprising a
support arranged to have an ice body formed thereon,
comprising a hollow plastic tubular member open at a near
end and closed at a distal end. Refrigeration means
conduct refrigerated fluid through the open end of the
tubular member to refrigerate the support to a below
freezing temperature. Means are provided for moving a
container holding a body of water to move liquid water
contained therein uniformly about the support suitable to
cause a clear substantially symmetrical ice body to build
up outwardly on the refrigerated support adjacent the
closed end of the tubular member. Means cause harvesting
of the ice body from the tubular member comprising means
conducting heated fluid through the open end of the tubular
member to heat the support to an above freezing
temperature. Means sense temperature of the fluid. The
means for causing harvesting of the ice body further
comprises means for terminating conduction of heated fluid
through the open end of the tubular member responsive to
temperature sensed by the sensing means being above a
select temperature value.
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There is disclosed in accordance with another
aspect of the invention cycle means for moving the
container to move liquid water contained therein uniformly
about the support suitable to cause a clear, substantially
symmetrical ice body to build up outwardly on the
refrigerated support. Storage means cause repositioning of
the container to withdraw the water in the container from
adjacent the support. Control means control operation of
the cycle means and the storage means and are operable to
operate the cycle means for a select time duration prior to
operation of the storage means during a batch operation of
the ice maker.
It is a feature of the invention that the control
means includes means for sensing temperature of the ice
maker and adaptive control means for varying the select
time duration responsive to sensed temperature to provide
uniform sized ice bodies in different batch operations of
the ice maker.
There is disclosed in accordance with a further
aspect of the invention an ice maker including a support
arranged to have an ice body formed thereon and means
refrigerating the support to a below freezing temperature.
A container is adapted to hold a body of water. A motor
controlled drive includes an electric motor operatively
coupled to the container for moving the container. A
control circuit controls energization of the motor includ-
ing means for determining duration of motor energization,
first drive means for energizing the motor for a first
select duration to raise the container, second drive means
for energizing the motor for a second select duration to
lower the container, and switching means for alternately
operating the first and second drive means in successive
dip cycles to reciprocally move the container to move
liquid water contained therein uniformly about the support
suitable to cause a clear, substantially symmetrical ice
body to build up outwardly on the refrigerated support.
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It is a feature of the invention that the motor
comprises a synchronous motor and the determining means
determines a number of power cycles for which the motor has
been energized.
It is a feature of the invention that the first
select duration is equivalent to the second select dura-
tion. ~ -
It is another feature of the invention that the
determining means comprises a counter means for storing a
value representing the duration.
It is an additional feature of the invention to
provide means for counting number of dip cycles and
reference means for operating one of the first and second
drive means after a select number of dip cycles to move the
container to a reference position and to thereafter reset
the counter to a reference value.
It is another feature of the invention to provide
storage means for causing repositioning of the container to
withdraw the water in the container from adjacent the
support and the control circuit controls operation of the
switching means and the storage means is operable to
operate the switching means for a select time duration
prior to operation of the storage means during a batch
operation of the ice maker.
It is a feature of the invention that the control
circuit includes means for sensing temperature of the ice
maker and adaptive control means for varying the select
time duration responsive to sensed temperature to provide
uniform sized ice bodies in different batch operations of
the ice maker.
It is another feature of the invention to provide
means for causing harvesting of the ice body from the
support comprising means for heating the support to an
above freezing temperature.
There is disclosed in accordance with yet another
aspect of the invention an ice maker comprising a support
arranged to have an ice body formed thereon and means for
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refrigerating the support to a below freezing temperature.
A container is adaptèd to hold a body of water. Means are
provided for moving the container to move liquid water
contained therein uniformly about the support suitable to
cause a clear, substantially symmetrical ice body to build
up outwardly on the refrigerated support. Storage means
cause repositioning of the container to withdraw the water
in the container from adjacent the support. Means are
provided for providing harvesting of the ice body from the
support. The means for moving liquid water about the
support includes means for utilizing a select volume of
water in the container to form the ice body, the select
volume being determined by level of water in the container
and temperature of the support, and means for adding a
fixed volume of water to the container subsequent to
harvesting of the ice body from the support to provide a
uniform, average volùme ice body over a plurality of ice
body making cycles.
It is a feature of the invention to provide a
control means for controlling operation of the moving means
for a select time duration prior to operation of the
storage means during a batch operation of the ice maker.
It is another feature of the invention that the
control means includes means for sensing temperature of the
ice maker and adaptive control means for varying the select
time duration responsive to sensed temperature to provide
uniform sized ice bodies in different batch operations of
the ice maker.
It is a feature of the invention that the
adaptive control means varies the select time generally
proportional to sensed temperature.
It is an additional feature of the invention that
the sensing means comprises a first charging circuit
including a temperature sensitive resistance, a second
charging circuit including a reference resistance and a
control circuit for alternately operating the first and
second charging circuits and comparing length of time
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required for each charging circuit to reach a select charge
level, a difference in such times representing ice maker
temperature.
Further features and advantages of the invention
will be readily apparent from the specification and from
the drawings.
Brief Description of the Drawinqs
Fig. 1 is a front elevation view showing a re-
frigeration apparatus including an ice maker according to
the invention;
Fig. 2 is a partial perspective view of the
refrigeration apparatus of Fig. 1 with a freezer door in an
open position;
Fig. 3 is a partial perspective view, with parts
removed for clarity and shown in cutaway of the ice maker
according to the invention;
Fig. 4 is an exploded view of the ice maker of
Fig. 3;
Fig. 5 is a detail side elevation view illus-
trating a spring bias of the stripper arm;
Figs. 6A and 6B comprise an electrical schematic
illustrating a control circuit for the ice maker;
Figs. 7A-7F comprise a series of flow diagrams
illustrating operation of a program in the microcontroller
of Fig. 5;
Fig. 8 is a front elevation view taken along the
line 8-8 of Fig. 3 with an ice tray support in a top dip
position;
Fig. 9 is a side elevation view taken along the
line 9-9 of Fig. 3 with an ice tray support in the top dip
position;
Fig. 10 is a view similar to that of Fig. 8 with
the tray support in a bottom dip position;
Fig. 11 is a view similar to that of Fig. 9 with
the tray support in the bottom dip position;
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Fig. 12 is a view similar to that of Fig. 8 with
the tray support in a harvest and park position;
Fig. 13 is a view similar to that of Fig. 9 with
the tray support in the harvest and park position;
Fig. 14 is a view similar to that of Fig. 8 with
the tray support in a dump position;
Fig. 15 is a view similar to that of Fig. 9 with
the tray support in the dump position;
Fig. 16 illustrates air flow paths during a
dipping cycle for the formation of an ice body;
Fig. 17 is a view similar to that of Fig. 16 at
the beginning of a harvest cycle;
Fig. 18 is a view similar to that of Fig. 17 at
the completion of the harvest cycle;
Fig. 19 is a perspective view illustrating a
normal sized ice body formed with the ice maker of Fig. 3;
Fig. 20 is a partial perspective view illustrat-
ing a shorter and thicker ice body as compared to that of
Fig. 19;
Fig. 21 is a perspective view illustrating a
taller and thinner ice body as compared to that of Fig. 19;
Fig. 22 is a curve illustrating data stored by
the microprocessor for implementing an adaptive control
scheme for providing uniform sized ice bodies; and
Fig. 23 is a graph illustrating a relationship
between charge time and temperature for a temperature
sensing routine used in the adaptive control scheme.
Description of the Invention
With reference to Fig. 1, a refrigeration
apparatus 10, comprising a side-by-side
refrigerator/freezer, includes a cabinet 12 housing a
storage space 14. Particularly, the storage space 14
comprises a below-freezing, or freezer, compartment 16, and
an above-freezing, or fresh food, refrigerator compartment
18. Access to the compartments 16 and 18 is had through
respective freezer and refrigerator doors 20 and 22,
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respectively, hingedly mounted to the cabinets 12, as is
well known.
The freezer door 20 is provided with a through-
the-door ice dispensing apparatus 24. The dispensing
apparatus 24 is partially contained within a housing 26,
see Fig. 2, suitably mounted in the freezer door 20.
With reference also to Fig. 2, an ice container
assembly 28 in the freezer compartment 16 stores ice bodies
which are delivered thereto from a superjacent ice maker 30
according to the invention. A door 32 is hingedly mounted
in the freezer compartment 16 to provide selective access
to the ice maker 30. The ice container assembly 28
includes a conveyor structure of any known form for
conveying ice cubes to a downwardly facing discharge
opening 34.
The freezer door 20 includes an interior panel 36
including an opening 38 in communication with an ice chute
40. When the door 20 is in the closed position, the
opening 38 is positioned immediately below the container
assembly discharge opening 34. Ice bodies may be obtained
by placing a suitable container against an actuator 42, see
Fig. 1, which opens a closure (not shown) and actuates the
ice container assembly 28 to deliver ice bodies to the
chute 40 for dispensing. Suitable switching devices are
provided for actuating the conveyor structure, as is well
known. An additional lever 44 is provided for dispensing
chilled water. The structure for doing the same is not
specifically disclosed herein as it does not relate to the
invention.
With reference to Figs. 3 and 4, the ice maker 30
is illustrated in greater detail. The ice maker 30
provides clear ice by freezing water in a manner such that
gases in solution can escape. To provide a smooth ice body
with a crystal clear appearance, the ice maker 30 provides
a relative motion between the freezing ice and the bulk
water volume it is freezing from. This motion polishes the
ice surface while it is freezing and mixes the bulk water
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volume it is freezing from to maintain uniform temperature
in the freezing bath. Further, the ice bodies have dry,
frozen surfaces when placed into the container assembly 28
to prevent the ice bodies from freezing into a large
unusable mass. Finally, the ice maker 30 prevents the
water volume from freezing and periodically dumps the same
to maintain a usable low solids and salt content freezing
bath and to prevent freeze up when it is not making ice.
The ice maker 30 comprises a housing 50 including
front and rear wall housings 52 and 54, respectively,
sandwiching a lower plenum housing 56. An upper plenum
housing 58 is received atop the lower plenum housing 56 and
is covered by a top cover wall 60. An outside wall 62 also
extends between the front and rear wall housings 52 and 54,
respectively, below the lower plenum housing 56.
For simplicity herein, the end of the ice maker
defined by the front wall housing 52 is referred to as the
front portion as it is positioned front most in the freezer
space 16 in use, while the rear wall housing 54 is
positioned near a rear wall in the freezer space 16.
Similarly, the outside wall 62 is positioned adjacent an
outside wall of the freezer space 16, i.e. to the left in
Figs. 1 and 2, while an opposite portion is referred to
herein as inside.
The lower plenum housing 56 is of integral
plastic construction. The housing 56 includes an inside
wall 64 and outside wall portion 66 connected by front and
rear walls 68 and 70. A lower wall 72 is connected between
the front and rear walls 68 and 70, to the outside wall 66
and to an intermediate wall 74 to define an outer, upwardly
opening space 76. A somewhat elevated inside lower wall
portion 78 is connected between the intermediate wall 74
and the inside wall 64 and also between the front and rear
walls 68 and 70, respectively, and defines an inner,
upwardly opening spàce 80. The lower wall portion 78
includes a plurality of through openings 82 connected to
downwardly depending fingers 84. Particularly, in the
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2114671
illustrated embodiment, there are fifteen openings 82 and
connected fingers 84. The fingers 84 comprise supports
arranged to have an ice body formed thereon. With
reference to Fig. 16, each finger 84 comprises a hollow
tubular member open at a top end 86 to the opening 82 and
closed at a lower, distal and rounded end 88. The lower
end 88 is shaped to provide the configuration for the
inside of an ice body B to be formed thereon, as
illustrated.
The lower plenum housing outer space 76 houses an
electrical control board 90 and blower motor 92 rearwardly
thereof. The blower motor 92 has an upwardly extending
vertical shaft 94.
The upper plenum housing 58 comprises a generally
rectangular horizontal wall 96. The wall 96 is of a size
and configuration to fit atop the lower plenum housing 56
and between the front and rear walls 68 and 70,
respectively, and the inside and outside walls 64 and 66,
respectively. The horizontal wall 96 includes an enlarged
circular opening 98 having its center corresponding to and
for receiving the motor shaft 94. An innermost section 100
of the wall 96 includes a plurality of openings 102. A
plurality of hollow, downwardly depending tubes 104 extend
from the inner wall portion 100, one at each opening 102,
see Fig. 16. Each tube 104 is received in one of the
fingers 84 incident to placement of the upper plenum
housing 58 on the lower plenum housing 56, as discussed
above. Each tube 104 is opened at a lower end 106.
To facilitate alignment of the tubes 104 and the
fingers 84, each finger includes a pair of vertical, criss-
crossed crescent-shaped walls 108 and 110. An upper arc
surface 112 on the walls 108 and 110 centers the tube 104
in the finger 84 to maintain a uniform space 114
therebetween around the entire periphery of the tube 104.
The cover 60 is of a size corresponding to the
upper and lower plenum housings 58 and 56, respectively,
except for a rectangular cutout 116. Prior to installing
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the cover atop the lower plenum housing 56, a blower wheel
118 is mounted to the motor shaft 94 above the upper plenum
housing wall 96.
A damper 120 is mounted between the cover 60 and
the front wall 52 at the opening 116. The damper 120 is
pivotal about an axis represented by the line 122 for
controlling air flow.
The blower wheel 118 is configured so that
suction is present at the upper plenum housing opening 98
and its discharge is as indicated by an arrow 124, see Fig.
4, toward the cover opening 116. With suction at the
opening 98, air is drawn from a space 126 between the cover
60 and upper plenum housing wall 100, see Fig. 16, and
downwardly through the tube 104. Air exits the tube 104
around its lower end 106 and into the space 114 between the
tube 104 and the finger 84 and exits into the space 80
where it returns to the suction side of the blower wheel
118.
The source of air flow depends on the position of
the damper 120. Particularly, when the damper 120 is in an
open position, as illustrated in Fig. 9, air at a below-
freezing temperature is drawn into the space 126, as
illustrated, so that below-freezing fluid, in the form of
refrigerated air, passes through the fingers 84 to
refrigerate the same. Exhaust air exits above the damper
120, as illustrated. When the damper 120 is in a closed
position, as illustrated in Fig. 13, exhaust from the
blower wheel 100 is recirculated into the space 126 so that
below-freezing air is not used. In fact, a heater element
128 on the control board 90 is energized during specified
operational cycle times when the damper 120 is closed so
that the circulating air is heated, as discussed below.
The rear wall housing 54 includes a rear wall 130
formed with a series of front facing tracks 132 for
controlling movement of a tray carrier 134. The tracks 132
include a generally horizontal elongate lower through
opening 136 connected at an inner end to a vertical through
- 211~671
opening 138 and an outer end to an arcuate upwardly
extending through opening 140. The lower horizontal
opening 136 also continues at its rear end to a counter
bored groove 142 below the arcuate opening 140, see Fig. 9.
An upper horizontal elongate groove 144 is provided in
parallel to the lower opening 136 and is connected to the
front vertical opening 138 at its inner end and to an
arcuate portion 146 at its outer end. An outer vertical
groove 148 is parallel to and spaced outwardly from the
inner vertical opening 138. The vertical groove 148
connects at a lower end to the lower horizontal opening 136
and crosses the horizontal groove 144.
Although not specifically described herein, the
front wall housing 52 includes a front wall having similar
tracks formed therein, albeit a mirror image, facing the
tracks 132 on the rear wall 54 to guide movement of the
carrier 134.
The carrier 134 includes a bottom wall 150
connected to a vertical outer wall 152 and front and rear
walls 154 and 156, respectively. Extending frontwardly
from the front wall 154 are three pins 157, 158 and 160 in
a triangular configuration. The lower, innermost pin 160
is longer than the pins 157 and 158, with the pin 158 being
directly above the pin 160 and the pin 157 being outwardly
thereof to define an obtuse angle vertex of the triangular
configuration. Alth~ough not specifically discussed, the
rear wall 156 includes a similar array of pins extending
rearwardly therefrom.
The carrier 134 is received between the front
wall housing 52 and the rear wall housing 54, as shown in
Fig. 3. Particularly, the pins are received in the tracks
132 for guiding movement. This relationship can be best
understood with reference initially to Fig. 9 when viewing
the position of the pins 157, 158 and 160 relative to the
tracks 132 of the rear housing wall 54.
The pin 160, being longer than the pins 157 and
158 extends through either the approximately horizontal
. . 211467~
opening 136 or the vertical opening 138. Indeed, the pin
160 is driven by a structure described below to control
movement of the carrier 134. The pins 157 and 158 are
received in the tracks to maintain the carrier 134 in a
desired orientation. During vertical movement of the
carrier 134, the pins 157 and 158 are received in the
respective vertical groove 148-and vertical through opening
138, as illustrated in Fig. 9. During horizontal movement
of the carrier 134, the upper pin 158 is received in the
upper groove 144 while the lower pin 157 is received in the
lower approximately horizontal through opening 136, as
illustrated in Fig. 13. During a dump cycle, the upper pin
158 is received in the upper arcuate groove 146, while the
lower pin 157 is received in the lower substantially
horizontal groove 142 to tip the carrier 134, as
illustrated in Fig. 15.
A water tray 162 is carried on the support 150
and includes an inner wall 164 connected to a formed
housing 166 defining an upwardly opening space 168 to be
filled with a volume of water. The space 168 is large
enough to accommodate the fifteen fingers 84 and provide
ample space around each finger 84 for the formation of an
ice body, as described below. Front and rear ridges 170
and 172, respectively, are receivable in facing tracks 174
and 176 in the carrier front and rear walls 154 and 156,
see Fig. 4.
In order to prevent freezing of water stored in
the space 168, a resistance heater wire 178 is supported on
the carrier bottom wall 150 between the tray carrier 134
and the tray 162. The resistance heater wire 178 is
connected to the pin 160 at each end which comprises a
conductive pin for connection to an electrical circuit as
discussed below.
To control movement of the carrier 134, front and
rear cams 180 and 182 are used. The front cam 180 is posi-
tioned in the front wall housing 52 and the rear cam 182 is
positioned in the rear wall housing 54, as illustrated.
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- - 2114671
With reference to Fig. 3, the front cam 180 is
generally circular in configuration and includes a central
opening 184 for receiving a shaft 186 connecting the front
cam 180 to the rear cam 182 at an opening 188, see Fig. 4.
The front cam 180 includes a generally semi-circular
section 190 having an outer circumferential, toothed
surface 192. An elongate arm portion 194 extends from the
semi-circular portion 190 in a quadrant clockwise from the
circular portion as viewed in Fig. 3. A continuous ridge
196 extending frontwardly from the cam 180 defines an
elongate groove 198 including a circumferential portion 200
generally parallel to the outer toothed wall 192 and
connected to a curved radially inwardly directed portion
202. The groove 198 receives a pin 204 on an arm 206 which
connects to a pin 208 on the damper 120 for controlling
positioning of the same.
The cam arm portion 194 includes a radially
extending through slot 210 spaced from the central opening
184. The through slot 210 receives the longer, conductive
pin 160 from the carrier 134, as illustrated in Fig. 8.
The front cam 180 is driven by a synchronous
motor 212 driving a gear 214 extending through an opening
216 in the front wall housing 52. Particularly, the gear
214 engages the toothed outer surface 192 to rotate the cam
180 about an axis of the shaft 186. Rotational movement of
the front cam 180 is converted to linear movement of the
pin 160 guided in the openings 138 and 136. Rotation of
the shaft 186 also drives the rear cam 182. The rear cam
182 is generally semi-circular in shape and also includes
an elongate radial slot 218 for receiving a conductive pin
160 from the rear wall 156 of the carrier 134. Thus, the
motor 212 is operable to drive the carrier 134 at both ends
using the cams 180 and 182 to provide controlled, uniform
movement of the carrier 134 and the tray 162.
To operate the heater 178, a pair of terminals in
the form of spring switch blades 220 are used, one
associated with the front cam 180 and the other the rear
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cam 182. As illustrated in Fig. 3, one blade 220 is
mounted to the front wall housing 52 so that it extends
across the inner vertical slot 138 about a central portion
thereof. As particularly illustrated in Fig. 8, the
conductive pin 160 extends through the vertical slot 138
and the cam slot 210. When the pin 160 is in the vertical
opening 138 about its midpoint, it is engaged by the blade
220. Although not specifically illustrated, a similar
connection is provided at the rear wall housing 54. Thus,
when power is applied to the spring blades 220 and the
carrier 134 is in the suitable position, the heater wire
178, see Fig. 4, is energized.
In order to sense a reference or zero position of
the cam 180, a zero reference switch 230 is mounted in the
front wall housing 52 in an upper right-hand corner as
viewed in Fig. 3. The switch 230 includes an actuator 232,
see Fig. 10, actuated by the cam arm 194 when the carrier
134 is in a top dip position, see Fig. 8.
When the container assembly 28, see Figs. 1 and
2, is full of ice bodies, it is desirable to prevent
further operation of the ice maker 30. In accordance
therewith, a bin arm 234 is provided for sensing the level
of ice bodies. The bin arm 234 is pivotally mounted to the
rear wall housing 54 as at an opening 236 and through a
similar opening in tpe front wall housing 52 where it is
mounted to a lever 238. The lever 238 is supported in an
"up" position when the carrier 134 is controlled for
vertical movement, as by the arm portion 194 being at
approximately a "four o'clock" position, see Figs 8 and 10.
The lever is released when the carrier 134 is controlled
for horizontal movement , as by the arm portion 194 being
at approximately a "seven o'clock" position, see Fig. 12.
When the lever 238 is released, it actuates an actuator 240
of a bin arm switch 242.
In order to facilitate harvesting of ice bodies
from the fingers 84, a stripper 244, see Fig. 4, is used.
The stripper 244 includes front and rear arms 246 and 248,
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211 ~-~671
respectively, connecting a cross ~bar 250. Extending
transversely from the cross bar 250 are a plurality of
oppositely directed, flexible stripper blades 252. Outer
ends of the arms 246 and 248 are connected to a torque bar
254 for pivotal movement. Each stripper blade is
positioned alongside one finger 84. The torque bar 254
extends through an opening 256 in the lower plenum front
wall 68 when it is connected to the front arm 246, see Fig.
5. A spring 258 engaging a tab 260 biases the arm 246
downwardly. The rear cam 182 includes a frontwardly
directed cam actuator 264 for bearing on the stripper arm
248 to force the same upwardly when the cams are rotated
for providing vertical reciprocal movement of the tray
carrier 134. Although not shown, the front cam 180
includes a similar cam actuator.
When assembled, the front and rear wall housings
52 and 54 are fastened to the lower housing plenum 56 using
suitable fasteners (not shown). Front and rear cover
plates 266 and 268, see Fig. 4, are subsequently fastened
to their respective housings 52 and 54 to cover the same.
The outer wall 62 includes a lower, rearwardly
and downwardly directed trough 270 for dumping water when
necessary. When installed in a freezer compartment, a rear
portion of the trough 270 is positioned adjacent suitable
apparatus for disposing of such water.
In order to fill the tray 162 with water an
opening 272 is provided through the cover 60 at a rear
inner corner thereof communicating with similar opening 274
in the lower plenum housing 56 positioned above the tray
162. Although not shown, a hose would be positioned in
such opening and connected via a solenoid valve 342, see
Fig. 6B, to a source of water for filling the tray 162 as
necessary.
With reference to Figs. 6A and 6B, a schematic
diagram illustrates a control circuit for the ice maker 30.
AC power is provided across terminals labelled L1
and N to a power supply circuit 300. The power supply
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circuit 300 is a conventional such circuit for converting
AC power to DC power at suitable level for operating the
various components described below, including a CPU 302.
The CPU comprises a conventional microcontroller including
onboard microprocessor and associated RAM and ROM memory
circuits, as is well known. Particularly, the CPU 302 is
connected to plural input and output devices and is
operated by a control program, as described below, for
controlling output devices based on status of input
devices.
A zero cross detecting circuit 304 is connected
to the power supply circuit 300 and an input port of the
CPU 302. The zero cross detector circuit 304 provides a
discrete input to the CPU 302 at each zero crossing of the
AC supply for counting cycles of input power. More
particularly, the line cycle count is used for determining
position of the tray 162, see Fig. 4, based on the number
of cycles in which power is supplied to the motor 212,
comprising a synchronous motor. As is known, with a
synchronous motor the number of motor shaft turns is
directly related to the number of power cycles applied to
the motor windings.
A power on'reset circuit 306 is connected to an
additional input of the CPU 302. The power on reset
circuit 306 provides a pulse when power is first supplied
for resetting the CPU 302 to a select, initial operating
mode.
A zero switch circuit 308 is connected to an
additional input of the CPU 302. The zero switch circuit
308 includes a contact switch 310 associated with the zero
reference switch 230, see Fig. 3. This contact is used for
indicating a reference position of the tray 162, see Fig.
4.
A bin switch circuit 312 is connected to an
additional input port of the CPU 302. The bin switch
circuit 312 includes a contact 314 associated with the bin
arm switch 242, see Fig. 3. The bin switch circuit 312
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211~1~7~
provides an input to the CPU indicating the position of the
bin arm 234.
A stripper'switch circuit 316 is connected to a
further input of the CPU 302. The stripper switch circuit
316 includes a contact 318 associated with a stripper
switch 320 on the electrical control board 90, see Fig. 4.
The stripper arm switch 320 includes an actuator 322
sensing position of the stripper cross bar 250.
Particularly, when the stripper cross bar 250 is in a
raised position as caused by the cam 264, see Fig. 9, or
ice bodies are present on the fingers 84, the contact 318
is in a normally open position. When the cam 64 permits
the stripper to drop under bias of the spring 258 and there
are no ice bodies present on the fingers 84, then the
stripper arm switch 320 is actuated to close the contact
318.
A temperature sensing circuit 324 is used for
determining freezer compartment temperature. Particularly,
the temperature sensing circuit 324 senses temperature of
air flow through the ice maker 30, represented by the arrow
124 of Fig. 4.
The temperature sensing circuit 324 includes dual
outputs from the CPU 302 connected to a parallel
calibration resistor 326 and a thermistor 328. The
junction between the resistor 326 and thermistor 328 is
also connected to a capacitor 330 and to an input of the
CPU 302. The resistor 326, thermistor 328 and capacitor
330 are all mounted on the control board 90, see Fig. 4.
The CPU 302 includes six additional output ports
connected one each for driving a tray up drive circuit 332,
a tray down drive circuit 333, a water valve drive circuit
334, a harvest heater drive circuit 335, a fan drive
circuit 336 and a tray heater drive circuit 337, see Fig.
6B. Each of the drive circuits 332-337 includes a
respective triac labelled S1-S6 gated by the associated
output from the CPU 302 and connected to the L1 side of the
power source.
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2114671
The drive motor 212, see Fig. 4, includes
separate forward and reverse windings 338 and 340. One
side of the winding 338 is connected to the triac S1 of the
tray up drive circuit 332. One side of the winding 340 is
connected to the triac S2 of the tray down drive circuit
333. An opposite side of each winding 338 and 340 is
connected to the neutral terminal. Particularly, when the
winding 338 is energized, the motor 212 is driven to drive
the cam 180 counterclockwise to raise the carrier 134 and
thus the tray 162. Conversely, when the winding 340 is
energized, the motor 212 is operated to drive the cam 180
clockwise to lower the carrier 134 and thus the tray 162.
The water valve drive circuit 334 includes a
solenoid valve 342 connected between the associated triac
S3 and the neutral terminal. The water valve 342 is used
for filling the tray 162 with a select volume of water.
The harvest heater drive circuit 335 includes the
harvest heater 128, see Fig. 4, comprising a heating ele-
ment 344 and a thermal fuse 346 connected between the
neutral terminal and the associated triac S4.
The fan drive circuit 336 includes the blower
motor 92 connected between the neutral terminal and the
triac S5 of the fan drive circuit 336.
The tray heater circuit 337 includes the tray
heater 178 connected between the conductive pins 160 and
blade wipers 220 between the neutral terminal and the triac
S6 of the tray heater drive circuit 337.
With reference to Figs. 7A-7F, a flow diagram
illustrates a control program implemented by the CPU 302,
see Fig. 6A, for controlling operation of the ice maker 30,
see Fig. 2.
With reference initially to Fig. 7A, the program
begins with a start node upon power up when a power up
reset signal is received from the circuit 306. At a block
402 the program turns the tray up signal on by gating the
triac S1 to energize the winding 338, see Fig. 6B. This
drives the tray 162 continuously. A decision block 404
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determines if the tray 162 is at the top position by
checking the status of the zero switch circuit 308. If the
tray 162 is not at the top, then a decision block 406
determines if a screw count value is greater than or equal
to 600. Particularly, the two decision blocks 404 and 406
comprise a timing loop which counts the number of turns or
revolutions of the motor 212 based on the number of 60 Hz
pulses received from the zero crossing circuit 304. If the
screw count is not greater than or equal to 600, then
control loops back to the decision block 404. If the screw
count equals or exceeds 600, then an error or jam condition
is assumed to exist and a time out routine is called at a
block 408.
Once the tr~ay 162 is at the top, then at a block
410 the tray up output circuit 332 is turned off and the
screw count value is set equal to zero. The tray down
drive circuit 333 is then turned on to advance the tray 162
to the dump position. A decision block 412 loops on itself
until the tray is at the dump position. The tray is
determined to be at the dump position after 580 screw
turns, represented by 6960 60 Hz pulses from the zero cross
detector circuit 304. Once the tray 162 is at the dump
position, see Fig. 15, the tray down drive circuit 333 is
turned off at a block 414 and the fan drive circuit 336 is
turned on and control waits for five seconds. A decision
block 416 then determines if the bin switch is on as by
checking the status of the bin switch circuit 312, see Fig.
6A. Particularly, if the bin switch is on, i.e., the bin
arm 234 is in the down position, then additional ice is
needed and control advances via a node 1 to a block 418.
If not, then control advances via a node D2 to a park
routine described below relative to Fig. 7E.
At the block 418, the tray down drive circuit 333
is maintained de-energized and the harvest heater drive
circuit 335 is energized. Control then repeatedly
interrogates a series of decision blocks 420 and 422 until
either the sensed temperature is equal to 60~ or the
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stripper arm 244 is in a down position, indicating that no
ice bodies are present on the fingers 84. Once either of
these conditions is satisfied, then the harvest heater
drive circuit 335 is turned off at a block 424 and the tray
up drive circuit 332 is turned on.
The tray up drive circuit 332 iS maintained
energized while a decision block 426 checks the status of
the zero switch circuit 308 to sense when the tray 162 iS
at the top position, see Fig. 9. Concurrently, a decision
block 428 determines if the screw count is greater than or
equal to 600 and if so, then the time out routine is called
at a block 430, as discussed above. Once the tray 162 iS
at the top position, the tray up drive circuit 332 is de-
energized at a block 432 and the water drive circuit 334 is
lS turned on to fill the tray 162 with a select volume of
water. Particularly~, at this point the tray 162 having
come from a dump cycle is empty and therefore a long fill
cycle is to be used. A decision block 434 determines if
the long fill is done yet by providing an approximately
eighteen second cycle determined by counting pulses from
the zero cross detect circuit 34. Once the long fill is
done, then at a block 436 the water valve drive circuit 334
is turned off and a value for cycle count is set equal to
zero and control advances to a dip cycle shown in Fig. 7B.
The dip cycle begins at a decision block 440
which determines if a selected low temperature on the order
of 28 ~F is sensed by the thermistor 328. The control waits
until this condition is satisfied, at which time control
advances to a block 444 which sets a dip time equal to
zero. During a dipping cycle the tray heater 178 is
connected to the dri~ve circuit 337 through spring switch
blades 220, see Fig. 6B. However, the CPU 302 does not
maintain energization of the drive circuit 337. Instead,
the drive circuit 337 is pulse width modulated based on a
select duty cycle. The duty cycle for operating the tray
heater 178 is set at a block 446 based on an average
desired duty cycle. At a block 448 the tray down drive
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circuit 333 is energized, as is the tray heater drive
circuit 337. A decision block 450 determines if the tray
162 has been driven down four motor turns, i.e., 48 pulses
from the zero cross detector circuit 304. This is done to
ensure that the zero switch circuit 308 is no longer
engaged. The dip count value is then set equal to two at
a block 452. This is done to prevent too much use of the
zero reference switch 230, as discussed below.
A decision block 454 waits until the tray down
drive circuit 333 has been energized for nine hundred zero
crosses, i.e. seventy-five motor turns. At the expiration
of this wait time the tray down drive circuit 333 is de-
energized at a block 455 and the tray up drive circuit 332
is energized to stop down movement of the tray and provide
reciprocal up movement of the tray 162. During the dip
cycle the tray 162 is alternately operated to move up and
down for preselected motor cycle times to move the tray 162
up and down between the top dip position shown in Fig. 9
and a bottom dip position shown in Fig. 11. Particularly,
the CPU 302 counts the number of pulses input from the zero
cross detector circuit 304 and determines vertical movement
of the tray 162. In an exemplary embodiment of the
invention, the movement of the tray up and down is
approximately three-fourths of an inch, which may represent
seventy-five motor turns or nine hundred zero cross pulses
received. In order to prevent jam-ups, the zero reference
circuit 308 is used periodically to reset the programmable
counters which count the zero cross input cycles.
The reciprocal movement of the tray 152 results
in freezing the water about the fingers 82, as illustrated
in Fig. 16, so that gases in the solution can escape. The
dipping motion produced by reciprocal movement of the tray
162 relative to the fingers 82 provides a smooth ice body
B with a crystal clear appearance. This reciprocating
motion serves to polish the ice surface while it is
freezing and mixes the bulk water it is freezing from to
maintain uniform temperature in the bath. The bath is
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prevented from freezing by the tray heater 178 being
periodically energized in accordance with the said duty
cycle during the dipping operation.
Returning to the flow diagram, a decision block
456 determines if the tray up drive circuit 332 has been
energized for seventy-five turns of motor operation. If
so, then the tray up drive circuit 332 is turned off at a
block 458 and the dip count is decremented at a block 460.
A decision block 462 determines if the dip count is equal
to zero. If not, then control advances to the block 463 to
turn on the tray down drive circuit 333 and then to the
block 454 to continue alternate down and up movement of the
tray 162.
Once the dip count is equal to zero, as deter-
mined at the decision block 462, then it is necessary to
return the tray 162 to the zero reference position. To do
so, the tray up drive circuit 332 is turned on at a block
464. A decision block 466 then determines if the tray is
at the top reference position by checking the status of the
zero switch circuit 308. If not, then a decision block 468
determines if the screw count is equal to one hundred,
representing a greater than desirable distance between the
top dip position and the zero reference position. If so,
then the time out routine is called at a block 470. Other-
wise, the control continues to loop as by returning to the
decision block 466.
Once the tray is at the zero reference position,
then the tray up drive circuit 332 is turned off at a block
472 and the dip time is incremented. In accordance with
the invention, the motor 212 rotates approximately five
revolutions per second. The up time, represented by
seventy-five revolutions or turns, is fifteen seconds, as
is the down time. Therefore, the cycle includes two up
cycles and two down cycles prior to implementing the zero
calibration. Thus, the dip time for such a period is
approximately one minute so that the dip time is
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incremented by one minute at the block 472. An adapt
routine is then called at a block 474.
With reference to Fig. 7F, a flow diagram for the
adapt routine is illustrated, beginning at a block 476.
The adapt routine is used for calculating temperature of
circulating air, i.e., temperature in the freezer
compartment 16. To do so, a calibrate set up function is
implemented at a block 478 as by charging the capacitor 330
of the temperature circuit 324 through the calibration
resistor 326. Particularly, a reference voltage is applied
to the calibration resistor 326 until a threshold is
measured by the CPU 302 representing the charge in the
capacitor 330. The CPU 302 determines the charge time.
This generates a software calibration value used to
calibrate out most circuit errors. The capacitor 330 is
then discharged at a block 480. Then, at a block 482, the
capacitor 330 is charged through the thermistor 328. The
time to trip the preset threshold is measured and compared
to the calibration value to determine the actual resistance
of the thermistor 328. As is known, the resistance of the
thermistor 328 changes with temperature. The actual
temperature is represented by thermistor resistance which
is determined using a charge time relationship as
illustrated in Fig. 23. The resistance is computed at a
block 484 by multiplying the measured charge time (TM) of
the thermistor 328 and capacitor 330 by the calibration
resistance (Rc), and then dividing the result by the
calibrated charge time (Tc) of the resistor 326 and the
capacitor 330. The computed resistance value is added to
a sum register at a block 486 and the adapt routine ends by
returning to Fig. 7B.
Upon completion of the adapt routine, a decision
block 488 determines if the dip time is equal to a dip
average value labeled DIP AVG. This value represents a
desired dip cycle time.
If the dip time is not equal to the dip average,
then control advances via a node A to return to the block
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- 2114671
446 to continue the dip cycle. If the dip time is equal to
the dip average, then an average routine is called at a
block 490. The average routine is illustrated in Fig. 7F
beginning at a block 492. The average routine proceeds to
a block 494 which divides the sum register value,
determined at the block 486, by the dip average value.
Particularly, this divides the running total of recorded
temperature values by the amount of time allowed to take
temperature samples.
The freezer compartment temperature determines
the thickness of the ice bodies. For example, a normal
size ice body resulting at a normal freezer compartment
temperature is illustrated in Fig. 19. This ice body has
a height H1 and thickness Tl. If the available temperature
is higher, then the initial thickness will be less and
might be on the order of the thickness T2 illustrated in
Fig. 21. However, the ice will not change as height is
determined by level of water in tray 162. However, with a
thinner ice body less water is used. When the fixed quan-
tity of water is added to the tray 162 at the next fill,
then the level of water in the tray 162 increases so that
with each successive cycle, the height of the ice body will
increase up to the level H2 illustrated in Fig. 21. This
is a self-compensating feature which provides a uniform,
average volume ice body over long periods of time.
Conversely, under lower temperature conditions,
a thicker ice body such as on the order of thickness T3
illustrated in Fig. 20 results. This results in more water
being used and is added to each cycle so that eventually a
shorter ice body having a height H3, such as illustrated in
Fig. 20, results. This illustrates the self-compensating
feature under colder freezer conditions.
In order to provide a more uniform size ice body
under extreme temperature conditions, an adaptive control
may also be utilized. Under normal freezer conditions, the
size of the ice body is a function of dip time. However,
since the size may vary depending on freezer air tempera-
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~ 2114671
ture extremes, as discussed above, the dip time can be
varied in response to temperature.
With reference to Fig. 22, a non-linear curve
illustrates the relationship between freezer air
temperature and dip time to maintain a constant cube size
in accordance with the invention. For example, with a
freezer air temperature of 0~F, a dip time of approximately
seventy minutes is used. If the freezer air is +10~F, then
a dip time of one-hundred-ten minutes is used, while with
a freezer air temperature of +5~F a ninety minute dip time
is used. This approach provides consistent ice body size
independent of freezer temperature. To implement this
feature, at a block 496 the quotient of the sum and DIP AVG
values, representing average temperature, is compared to a
look-up table labeled DPTBL, representing a table of dip
times versus differential temperatures, to retrieve an
adjusted dip time. The table DPTBL correlates to the curve
of Fig. 22. The adjusted dip time value is stored in a
DIPSET register at a block 498. A corresponding HTTBL
table, representing tray heat duty cycle setting versus
temperature, is accessed at a block 500 to retrieve a value
stored in a HTSET register. Particularly, this register
value determines duty cycle of the tray heater 178. As
such, this routine is operable to decrease duty cycle of
the tray heater 178 under higher freezer compartment
temperature conditions to minimize energy consumption and
improve ice clarity. A decision block 502 then determines
if the dip time value is equal to dip set. In accordance
with the invention, if the sensed temperature was higher
than desirable, then the dip time would initially not yet
be equal to the dip set value and control would return via
the node A2 to the block 446, see Fig. 7B, to continue the
dipping cycle. Once the dip time is equal to dip set, then
the dip cycle is complete as by returning to the block 490,
see Fig. 7B.
Once the average routine is complete, then the
tray down drive circuit 333 is energized at a block 504 to
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proceed to the harvest cycle. A decision block 506 waits
until the tray 162 iS driven down four hundred and eighty
turns so that the tray 162 is in the harvest position shown
in Fig. 13. The tray down drive circuit 333 iS then turned
off at a block 504 and a cycle count is incremented. As
described above, when the tray 162 is in the harvest
position, the bin arm 234, the cam actuator 264 releases
the stripper 244 which is biased by the spring 252 down-
wardly. As a result, the stripper blades 2, which are
inherently flexible, move downwardly so that they are on
top of the ice bodies B as illustrated in Fig. 17 to indi-
vidually provide downward vertical pressure on each of the
ice bodies B. Also, as the cam 180 rotates to the park
position, the arm 206 positions the damper 120 in the
closed position as illustrated in Fig. 13.
When the tray carrier 134 moves from the bottom
dip position of Fig. 11 to the harvest position of Fig. 13,
the lever 238 is released, compare Fig. 10 to Fig. 12, to
permit the bin arm 234 to drop. If sufficient ice has
previously been harvested, it is not necessary to continue
further operation. This is determined by the status of the
bin arm 234. If the bin arm 234 falls sufficiently, then
additional ice is needed. This is determined at a block
506 at which the status of the bin arm 234 reflected by the
bin switch circuit 312 is read. If the bin switch is on,
as determined at a decision block 508, then additional ice
is needed and control advances via a node B to a harvest
cycle, see Fig. 7C. If the bin switch is not on, indicat-
ing that the ice bin is full, then control advances via a
node D to a park mode, see Fig. 7D.
With reference to Fig. 7C, the harvest cycle is
illustrated. The harvest cycle begins at a block 510 at
which the harvest heater drive circuit 335 is turned on to
energize the harvest~heater 128. Because the damper is in
the closed position, see Fig. 13, the heated air is then
circulated through the fingers 84 via the flow paths illus-
trated in Fig. 17. This heated air acts to slightly thaw
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211 46~
the insides of the ice bodies B to release them from the
fingers 84 in connection with the downward pressure of the
stripper blades 252. Because the bottom of the ice maker
30 is open, refrigerated air in the freezer compartment 16
circulates in the area surrounding the fingers 84 and ice
bodies B. This chilled air dries the outer surface of the
ice bodies B as by freezing any water remaining on the same
as the air is at a surface below 32~F.
The harvest cycle continues until the temperature
sensed by the thermistor 328 reaches an elevated
temperature on the order of 60~F as determined at a
decision block 511 or until the stripper arm 244 is down,
indicating all ice bodies have been stripped, as determined
by reading the status of the stripper arm switch 316 at a
block 512. At the completion of the harvest cycle, the
harvest heater drive circuit 335 is turned off at a block
513.
Periodically, it is desirable to dump remaining
water in the tray 162. In accordance with the invention,
this is done after the tray 162 has been in the park
position to dump stale water, or after a select number of
cycles. During the dipping cycle, only a portion of the
water in the tray 162 is used to form the ice bodies B. At
the beginning of the dip cycle, the tray is filled to
replenish the water used. However, the solids
concentration in the tray water will build up with each
successive cycle as the purer water is frozen from
solution. To ensure that clear ice is provided throughout
operation, it is desirable to occasionally dump the
residual water in the tray 162 to get rid of the solids,
i.e., the minerals and impurities that have built up in the
freezing bath.
At a decision block 514, a determination is made
if the cycle count is equal to zero. This occurs when the
harvest mode is implemented after the tray had been parked.
If so, then control advances via a node C1 to a first dump
mode illustrated in Fig. 7D. If the cycle count is not
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2114~7~
equal to zero, then a decision block 515 determines if the
cycle count is equal to a set cycle count. The set cycle
count is the desired number of cycles after which the tray
162 will be dumped. In an illustrated embodiment of the
invention, the set cycle value may be set to seven. If the
cycle count does equal the set cycle count, then the
control advances via a node C to the dump cycle of Fig. 7D.
If the cycle count is not equal to the set cycle
count, as determined at the decision block 515, then it is
necessary to proceed with a fill and dip cycle. Initially,
the tray up drive circuit 332 is energized at a block 516
and a decision block~517 waits until the tray is at the top
or zero reference position. Concurrently, a decision block
518 determines of the screw count is greater than or equal
to six hundred and if so calls the time out routine at a
block 519. Otherwise, control returns to the decision
block 517. Once the tray 162 is at the top, then the tray
up drive circuit 332 is turned off at a block 520. Also,
the water valve drive circuit 334 is turned on to begin a
normal fill of the tray 162. The decision block 522 waits
until the normal fill is done by waiting eight seconds as
represented by sixteen half second increments as determined
using the 60 Hz pulses from the zero cross detector circuit
304. Once the normal fill is done, then the water valve
drive circuit 334 is turned off at a block 524 and control
advances via a node A to the block 440 of Fig. 7B to begin
a new dipping cycle.'
With reference to Fig. 7D, the dump cycle is
described beginning from the node C at a block 526.
Initially, the tray down drive circuit 333 is energized to
move the tray carrier 134 to the dump position shown in
Fig. 15. A decision block 528 determines if the tray 126
is at the dump position based on a count value of one
hundred corresponding to twelve hundred zero cross pulses.
If so, then the tray down drive circuit 333 is turned off
at a block 530 and the cycle count value is reset to zero.
Thereafter, or if the dump cycle is initiated from the park
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mode via the node Cl, then the tray up drive circuit 332 is
turned on at a block 532 and a decision block 534
determines if the tray 162 is at the top position based on
the status of the zero switch circuit 308, see Fig. 6A. A
decision block 536 continually checks to determine if the
screw count value is greater than or equal to six hundred,
and if so calls the time out routine at a block 538. Once
the tray 162 is at the top position, then the tray up drive
circuit 332 is turned off at a block 540 and the water
valve drive circuit 334 is turned on to begin the long
fill. A decision block 542 waits for eighteen seconds, or
thirty-six half second increments, for the long fill. At
the completion of the long fill, the control returns via
the node A to the decision block 440 of Fig. 7B to commence
a dip cycle.
In accordance with the invention, prior to each
dipping cycle water is added to dilute remaining water in
the tray 162. The added water is equal to the volume of
water removed in the harvested ice. The desire is to avoid
the requirement of a drain being provided from the refrig-
erator. Instead, the water is only periodically sent to
the evaporator drip pan. Since the dump cycle is only
implemented periodically, the evaporator drip pan can
handle this volume of water without concern of being
overfilled.
With reference to Fig. 7E, the control for
implementing the park mode is illustrated beginning at a
block 544, which de-energizes the fan drive circuit 336 and
resets the cycle count equal to zero. The tray down drive
circuit 333 is turned on at a block 546 to move the tray
162 to the dump position to dump water from the tray 162 so
that it does not freeze. Once the tray 162 is at the dump
position, then the tray down drive circuit 333 is turned
off at a block 550 and control waits five seconds to allow
water to drain from the tray 162. The tray up drive
circuit is then turned on at a block 552 to move the tray
162 to the harvest position of Fig. 13. A decision block
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554 waits until the tray 162 is at the harvest position,
again based on twelve hundred zero cross pulses being
received. The tray up drive circuit 332 is then turned off
at a block 556 and the bin switch circuit 312 is checked.
A decision block 558 determines if the bin switch is on.
If not, then control remains at the block 558 with the tray
carrier 134 parked in the harvest position of Fig. 13 until
such time as sufficient ice bodies are removed so that the
bin arm 234 is dropped and the bin switch is turned on, at
which time the fan drive circuit 336 is turned on at a
block 560 and control advances via a node B to the harvest
cycle of Fig. 7C to begin a harvest cycle.
With reference to Fig. 7F, the time out routine
is illustrated. The time out routine begins at a block 562
which stores a count CNT value equal to ten. The zero
switch circuit 308 is then read at a block 564. A one
second wait is implemented at a block 566 and the count
value is decremented by one. A decision block 568 then
determines if the zero switch circuit 308 has been
satisfied. If not, then a decision block 570 determines if
the count value is equal to zero. If not, then control
loops back to the block 564. This routine is operable to
make ten attempts to read the zero switch circuit 308 with
one second between tries. Once the count value is equal to
zero, as determined at the block 570, then control advances
via a node A3 to the block 410 of Fig. 7A to de-energize
the tray up drive circuit 332 and proceed to the dump
position, as discussed above. If the zero switch circuit
308 is satisfied, as determined at the decision block 568,
then the time out r~outine ends and control proceeds as
normal, dependent upon the point in the operating cycle at
which the time out routine was called.
Thus, in accordance with the invention, a clear
ice maker is provided which reciprocally moves a volume of
water up and down relative to a refrigerated support to
form ice bodies. The pure water in the volume freezes
first, with solids in the solution settling to the bottom
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of a water tray. The water tray is eventually dumped and
~ its concentration increases to maintain the crystal clear-
ness of the formed ice bodies.
The illustrated embodiment of the invention is
illustrative of the broad inventive concepts comprehended
hereby.
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