U.S. patent number RE32,360 [Application Number 06/712,876] was granted by the patent office on 1987-02-24 for soft-serve freezer control.
This patent grant is currently assigned to Stoelting, Inc.. Invention is credited to Tom N. Martineau.
United States Patent |
RE32,360 |
Martineau |
February 24, 1987 |
Soft-serve freezer control
Abstract
A soft-serve freezer operates in a first mode, with both the
auger and compressor operating, and a second energy saving mode in
which only the refrigeration compressor operates. The control
circuit monitors the power level to the auger to control the
consistency of the mix. When the mix achieves a selected
consistency, the auger discontinues its mixing function. Signal
lights are provided to indicate when it is necessary to actuate the
auger to obtain the desired consistency prior to dispensing the
product and indicate that the mix has achieved the desired
consistency.
Inventors: |
Martineau; Tom N. (Clinton,
IA) |
Assignee: |
Stoelting, Inc. (Kiel,
WI)
|
Family
ID: |
26970816 |
Appl.
No.: |
06/712,876 |
Filed: |
March 18, 1985 |
Related U.S. Patent Documents
|
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
Reissue of: |
298677 |
Sep 2, 1981 |
04383417 |
May 17, 1983 |
|
|
Current U.S.
Class: |
62/127; 62/136;
62/233 |
Current CPC
Class: |
G05D
24/02 (20130101); A23G 9/228 (20130101) |
Current International
Class: |
A23G
9/22 (20060101); A23G 9/04 (20060101); G05D
24/00 (20060101); G05D 24/02 (20060101); A23G
009/00 (); F25C 001/00 () |
Field of
Search: |
;62/135,136,157,158,233,353,354,342,340,127,130,126,125,66,68,129,139 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Other References
Control and Instrumentation, vol. 1, No. 4, Aug. 1969, p. 54,
London, "Viscosity Control by Hall Effect Watt
Transducers"..
|
Primary Examiner: Tanner; Harry
Attorney, Agent or Firm: Fuller, Puerner &
Hohenfeldt
Claims
I claim:
1. In a soft-serve freezer including a freezing chamber with a
spigot, a mixing element, a first motor for said mixing element and
a refrigeration system including a second motor for a compressor in
said refrigerator system, the improvement comprising control
circuit means for said first and second motors, said control
circuit means including electric power sensing means associated
with said first motor, said control circuit means providing an
operational sequence with first and second modes in which said
mixing element and said refrigeration system are operating
concurrently in a first mode until said power sensing means senses
a predetermined power input to said first motor corresponding to a
preselected consistency, whereupon said circuit is switched to said
second mode wherein said second motor is switched on and off at a
selected frequency and said circuit including manually operable
mode changing means to change to said first mode with said first
motor driving said mixing element in contemplation of the
dispensing of product from said spigot and said circuit remaining
in said second mode until said manually operable means are
actuated.
2. In a soft-serve freezer including a freezing chamber with a
spigot, a mixing element, a first motor for said mixing element and
a refrigeration system including a second motor for a compressor in
said refrigerator system, the improvement comprising control
circuit means for said first and second motors, said control
circuit means including electric power sensing means associated
with said first motor, said control circuit means providing an
operational sequence with first and second modes in which said
mixing element and said refrigeration system are operating
concurrently in a first mode until said power sensing means senses
a predetermined power input to said first motor corresponding to a
pre-selected consistency, whereupon said circuit is switched to
said second mode wherein said second motor is switched on and off
at a selected frequency and said circuit including manually
operable mode changing means to change to said first mode with said
first motor driving said mixing element in contemplation of the
dispensing of product from said spigot and said circuit remaining
in said second mode until said manually operable means are
actuated, and visual indicator means in said control circuit means
indicating that the desired consistency is not available for
dispensing after the freezer has been in the second mode for a
pre-selected number of cycles and that the freezer should be
switched to said first mode.
3. In a soft-serve freezer including a freezing chamber with a
spigot, a mixing element, a first motor for said mixing element and
a refrigeration system including a second motor for a compressor in
said refrigerator system, the improvement comprising control
circuit means for said first and second motors, said control
circuit means including electric power sensing means associated
with said first motor, said control circuit means providing an
operational sequence with first and second modes in which said
mixing element and said refrigeration system are operating
concurrently in a first mode until said power sensing means senses
a predetermined power input to said first motor corresponding to a
pre-selected consistency, whereupon said circuit is switched to
said second mode wherein said second motor is switched on and off
at a selected frequency and said circuit including manually
operable mode changing means to change to said first mode with said
first motor driving said mixing element in contemplation of the
dispensing of product from said spigot and said circuit remaining
in said second mode until said manually operable means are
actuated,
an ambient temperature sensing means in said control circuit means
and wherein the duration of off periods for said second motor
during the second mode are determined by ambient temperature sensed
by said temperature sensing means, and
timer means in said control circuit means whereby the duration of
the on periods for said second motor during the second mode are
determined.
4. In a soft-serve freezer including a freezing chamber with a
spigot, a mixing element, a first motor for said mixing element and
a refrigeration system including a second motor for a compressor in
said refrigerator system, the improvement comprising control
circuit means for said first and second motors, said control
circuit means including electric power sensing means associated
with said first motor, said control circuit means providing an
operation sequence with first and second modes in which said mixing
element and said refrigeration system are operating concurrently in
a first mode until said power sensing means senses a predetermined
power input to said first motor corresponding to a pre-selected
consistency, whereupon said circuit is switched to said second mode
wherein said second motor is switched on and off at a selected
frequency and said circuit including manually operable mode
changing means to change to said first mode with said first motor
driving said mixing element in contemplation of the dispensing of
product from said spigot and said circuit remaining in said second
mode until said manually operable means are actuated, said control
circuit means including first and second light indicators with said
first light indicator indicating that the product does not have the
desired consistency for serving and said second light indicator
indicating that the power input level to the auger has achieved a
pre-selected level and that said product has achieved the selected
consistency and wherein said second light turns off after a
pre-selected time interval during the second mode to indicate that
the freezer should be switched to said first mode to activate the
mixing element prior to dispensing product.
5. In combination with a soft-serve freezer including a cylinder
and refrigeration coils for freezing a consummable mixture in the
cylinder, spigot means for dispensing frozen mixture from the
cylinder, an auger in the cylinder for agitating the mixture, an
auger drive motor coupled to the auger, a refrigeration compressor
for supplying refrigerant to said coils and a refrigerator motor
for driving the compressor, and an improved control circuit means
for the freezer said control circuit means comprising:
sensing means for sensing the electric power input level to said
auger motor to thereby provide an indication of the viscosity of
the mixture,
means for responding to said sensing means to cause said control
means to deenergize said auger and compressor motors when a
predetermined power load has been sensed,
first and second electric light sources and switching means for
selectively turning said light sources on and off, said switching
means being operative to keep said first light source turned on
during the time said motors are energized and bring the mix to the
desired consistency and to turn off said first light source when
said predetermined power input to said auger motor is attained and
then to turn on said second light source to indicate that the
desired consistency has been attained and said mixture is ready to
serve.
6. In combination with a soft-serve freezer including a cylinder
and refrigeration coils for freezing a consummable mixture in the
cylinder, spigot means for dispensing frozen mixture from the
cylinder, an auger in the cylinder for agitating the mixture, an
auger drive motor coupled to the auger, a refrigeration compressor
for supplying refrigerant to said coils and a refrigerator motor
for driving the compressor, and an improved controller for the
freezer comprising:
first control means for causing energization and deenergization of
said auger motor,
second control means for causing energization and deenergization of
said refrigerator motor,
a manually operable switch, said first and second control means
responding to operation of said switch by energizing said auger
motor and refrigerator motor for respectively agitating and cooling
said mixture in the cylinder,
sensing means for sensing the electric power input level to said
auger motor to thereby provide an indication of the viscosity of
the mixture,
means for responding to said sensing means sensing a predetermined
power level by causing said first and second control means to
deenergize said auger and compressor motors,
two electric light sources and switching means for selectively
turning said light sources on and off, said switching means being
operative to keep one light source turned on during the time said
motors are energized and to turn off said one light source when
said predetermined power input to said auger motor is attained and
then to turn on the other light source to indicate that said
mixture is ready to serve,
timer means for providing timing cycles composed of a sequence of
alternating first and second timing periods, the first period in
the first cycle commencing when said motors become deenergized and
periods of substantially similar duration being provided between
each of the second time periods, said refrigerator motor control
means responding to occurrence of said second time periods by
energizing said refrigerator motor for the duration of said second
time periods to thereby provide for cooling said mixture
periodically without energizing the auger motor.
7. In combination with a soft-serve freezer including a cylinder
and refrigeration coils for freezing a consummable mixture in the
cylinder, spigot means for dispensing frozen mixture from the
cylinder, an auger in the cylinder for agitating the mixture, an
auger drive motor coupled to the auger, a refrigeration compressor
for supplying refrigerant to said coils and a refrigerator motor
for driving the compressor, and an improved controller for the
freezer comprising:
first control means for causing energization and deenergization of
said refrigerator motor,
second control means for causing energization and deenergization of
said refrigerator motor,
a manually operable switch, said first and second control means
responding to operation of said switch by energizing said auger
motor and refrigerator motor for respectively agitating and cooling
said mixture in the cylinder,
sensing means for sensing the electric power input level to said
auger motor to thereby provide an indication of the viscosity of
the mixture,
means for responding to said sensing means sensing a predetermined
power level by causing said first and second control means to
deenergize said auger and compressor motors,
two electric light sources and switching means for selectively
turning said light sources on and off, said switching means being
operative to keep one light source turned on during the time said
motors are energized and to turn off said one light source when
said predetermined power input to said auger motor is attained and
then to turn on the other light source to indicate that said
mixture is ready to serve,
timer means for providing timing cycles composed of a sequence of
alternating first and second timing periods, the first period in
the first cycle commencing when said motors become deenergized and
periods of substantially similar duration being provided between
each of the second time periods, said refrigerator motor control
means responding to occurrence of said second time periods by
energizing said refrigerator motor for the duration of said second
time periods to thereby provide for cooling said mixture
periodically without energizing the auger motor, said controller
including counter means responsive to a predetermined number of
timing cycles having occurred by causing said light source
switching means to turn off said first light source and turn on the
other said second light source for the latter to indicate to the
operator that said manually operable switch should be actuated to
energize said compressor and auger motors to recondition said
mixture for serving.
8. The controller according to claim 7 wherein said timer means
comprises a first timer for providing said first time periods whose
durations are inversely proportional to ambient temperature and a
second timer for providing second time periods of a selected
constant duration.
9. In a soft-serve freezer including a freezing chamber with a
spigot, a mixing element, a first motor for said mixing element and
a refrigeration system including a second motor for a compressor in
said refrigeration system, the improvement comprising control
circuit means for said first and second motors, said control
circuit means including electric power sensing means associated
with said first motor, said control circuit means providing an
operational sequence with first and second modes in which said
mixing element and said refrigeration system are operating
concurrently in a first mode until said power sensing means senses
a predetermined power input to said first motor corresponding to a
pre-selected consistency, whereupon said circuit is switched to
said second mode wherein said second motor is switched on and off
at a selected frequency and said circuit including manually
operable mode changing means to change to said first mode with said
first motor driving said mixing element in contemplation of the
dispensing of product from said spigot and said circuit remaining
in said second mode until said manually operable means are actuated
and first and second signal lights connected in said circuit with
said first light indicating that the product is not at the selected
consistency and that the freezer should be switched to said first
mode and said second light indicating that the desired consistency
has been attained and that the product is ready to be
dispensed.
10. In a soft-serve freezer including a freezing chamber with a
spigot, a mixing element, a first motor for said mixing element and
a refrigeration system including a second motor for a compressor in
said refrigeration system, the improvement comprising control
circuit means for said first and second motors, said control
circuit means including electric power sensing means associated
with said first motor, said control circuit means providing an
operational sequence with first and second modes in which said
mixing element and said refrigeration system are operating
concurrently in a first mode until said power sensing means senses
a predetermined power input to said first motor corresponding to a
pre-selected consistency, whereupon said circuit is switched to
said second mode wherein said second motor is switched on and off
at a selected frequency and said circuit including manually
operable mode changing means to change to said first mode with said
first motor driving said mixing element in contemplation of the
dispensing of product from said spigot and said circuit remaining
in said second mode until said manually operable means are actuated
and first and second signal lights connected in said circuit with
said first light indicating that the product is not at the selected
consistency and that the freezer should be switched to said first
mode and said second light indicating that the desired consistency
has been attained and that the product is ready to be dispensed,
and means to reset said counter means upon actuation of said spigot
means after said mixture is ready to serve. .Iadd.
11. A soft-serve freezer including a freezing chamber with a
spigot, a mixing element, a first motor for said mixing element and
a refrigeration system including a second motor for a compressor in
said refrigerator system, control circuit means for said first and
second motors, said control circuit means including means for
providing an operational sequence with first and second modes in
which said mixing element and said refrigeration system are
operating concurrently in said first mode, means for automatically
switching said control circuit means into said second mode when a
predetermined consistency of the product is attained, said second
mode being a non-dispensing mode, timer means for switching said
second motor on and off at a selected interval independently of
said first motor in said second mode, adjustable means to control
the length of time the compressor is on and temperature responsive
means to control the time the compressor is off in said second
mode, and means operable to change to said first mode for
dispensing product and wherein said means operable to change to
said first mode includes manually operable mode changing means to
change to said first mode in which said first motor drives said
mixing element in contemplation of the dispensing product from said
spigot and said control circuit means remaining in said second mode
until said manually operable means are actuated, and wherein said
control circuit means includes ambient temperature sensing means
and wherein the duration of off periods for said second motor
during the second mode are determined by ambient temperature sensed
by said temperature sensing means, and timer means in said control
circuit means for determining the duration of the on periods for
said second motor during the second mode. .Iaddend. .Iadd.12. A
soft-serve freezer according to claim 11 wherein the means for
automatically switching the control circuit means into said second
mode when a predetermined consistency of the product is obtained
includes electric power sensing means associated with said first
motor and operable to sense a predetermined power input to said
first motor corresponding to
said predetermined consistency. .Iaddend. .Iadd.13. A soft-serve
freezer according to claim 11 characterized by visual indicator
means in said control circuit means indicating that the existing
consistency is not the consistency desired for dispensing product
after the freezer has been in the second mode for a pre-selected
number of cycles and that the freezer should be switched to said
first mode. .Iaddend. .Iadd.14. A soft-serve freezer according to
claim 11 wherein the temperature responsive means includes ambient
temperature sensing means in said control circuit means and timer
means responsive to variations in ambient temperature by varying
the duration of off periods for said second motor during the second
mode ambient temperature sensed by said temperature sensing means.
.Iaddend. .Iadd.15. A soft-serve freezer according to claim 11
wherein the control circuit means includes first and second light
indicators with said first light indicator indicating that the
product does not have the desired consistency for serving and said
second light indicator indicating that the power input level to the
mixing element has achieved a pre-selected level and that said
product has achieved the selected consistency and wherein said
second light turns off after a pre-selected time interval during
the second mode to indicate that the freezer should be switched to
said first mode to activate the mixing element prior to dispensing
product. .Iaddend. .Iadd.16. A soft-serve freezer according to
claim 11 wherein said mode changing means in said circuit comprises
a switch associated with a dispensing spigot which causes said
first motor to be energized upon activation of said spigot.
.Iaddend. .Iadd.17. A soft-serve freezer according to claim 12
wherein said control circuit means includes means responsive to
said power sensing means to cause said control circuit means to
de-energize said first and second motors when a predetermined load
has been sensed, two electric light sources and switching means for
selectively turning said light sources on and off, said switching
means being operative to keep one light source turned on at least
during said first mode in which said first and second motors are
energized and to turn off said one light source when said
predetermined power input to said first motor is sensed and then to
turn on said other light source to indicate that the desired
consistency is attained for dispensing. .Iaddend. .Iadd.18. A
soft-serve freezer according to claim 11 wherein said control
circuit means includes timer means for providing during said second
mode timing cycles composed of a sequence of alternating first and
second timing periods, the first period in the first cycle
commencing when said first and second motors are de-energized at
the end of the first mode and periods of substantially similar
duration being provided between each of the second time periods,
said second motor being switched on for the duration of said second
time periods to actuate said compressor independently of actuation
of said mixing element. .Iaddend. .Iadd.19. A soft-serve freezer
according to claim 17 wherein said control circuit means includes
counter means responsive to a predetermined number of timing cycles
to cause said light source switching means to turn on said one
light source and to turn off said other light source to indicate to
the operator that said manually operable switch should be actuated
to change to said first mode. .Iaddend. .Iadd.20. A soft-serve
freezer according to claim 18 wherein said control circuit means
includes reset means operable to reset said counter means upon
actuation of said spigot. .Iaddend. .Iadd.21. A soft-serve freezer
according to any one of claims 17, 18 or 19 wherein said timer
means comprises a first timer for providing said first timing
periods whose durations are inversely proportional to ambient
temperature and second timer for providing said second timing
periods of a selected constant duration. .Iaddend.
Description
BACKGROUND OF THE INVENTION
This invention relates to soft-serve freezers of the type used to
manufacture and dispense products such as frozen custard, ice
cream, ice milk and the like. In particular, the invention is
concerned with providing control for minimizing electric power
consumption, minimizing wear of moving parts and apprising the
operator of the condition of the product so that it can be
assuredly put in optimum consistency before it is served.
Generally, soft-serve freezers are comprised of a freezing cylinder
that is charged with a suitable mix from a storage hopper. A motor
driven auger is located concentrically within the cylinder and it
serves to agitate and whip the mix during freezing and to force the
mix out through a spigot when it is manually opened to dispense
product.
Typically, soft-serve freezers are used to dispense an ice cream or
custard mix which has a suitable consistency for being consumed as
a ice cream cone or a sundae, for example. In retail outlets where
such products are customarily sold, dispensation of product to
customers may occur at high or low periodicity. However, the
product must be available at a temperature and consistency that
provides customer satisfaction when it is served.
SUMMARY OF THE INVENTION
An important object of the present invention is to provide a
control system which minimizes electric energy consumption by the
dispensing freezer, particularly when it is standing in an idle
condition but is maintained in a state of readiness for serving
product. An adjunct to this object is to provide for the freezer
going automatically into an electric energy-saving mode such as
overnight or at other times during which product is not being
dispensed or is being dispensed infrequently.
Another object is to provide for only refrigerating the product
during the energy-saving mode, that is, avoiding use of the auger
agitator during this mode. A corollary to this object is that the
creamy mix does not become overagitated or excessively aerated
which is manifested by the dispensed product being too fluidic and
unattractive as is the case in some pre-existing dispensing
freezers.
Another object is to provide for avoiding unnecessary operational
intervals of the auger, not only for the purpose of conserving
electric power, but also for minimizing wear of the drive system
and wear between the auger blades and the freezing cylinder.
A very important object is to provide a visual indication of the
condition of the mix so that the operator can respond by taking
simple measures to optimize the condition. A corollary to this
object is to provide a visual indication to the operator that the
freezer has been in its energy-minimizing mode for such a long time
that agitation of the mix is required before a serving is
dispensed. In addition, a visual indication, such as by means of a
lamp and legend, is provided to the operator as an indication that
a push-button switch should be pressed to bring about optimization
of the consistency of the mix by agitating it and refrigerating it
further in contemplation of dispensing the next serving. Further, a
visual indication is provided a short time thereafter, as to when
the mix is ready to serve.
Another feature of the new control system is that it determines and
controls consistency of the mix precisely by monitoring the wattage
consumed by the auger drive motor. Three inaccurate but commonly
used prior art methods for determining consistency were to simply
monitor motor current, refrigeration suction line temperature or
pressure or the mechanical torque imposed on the auger.
In a dispensing freezer with which the new control system may be
used, liquid ice cream mix is frozen to the walls of a cylinder and
an auger in the cylinder scrapes the mix off and mixes or agitates
it. As temperature of the mix inside of the cylinder falls and
continued freezing takes place, the viscosity of the mix increases.
The term "auger" as used herein is intended to be a generic
designation for any paddles, augers or beaters and the like which
may be used to agitate the consummable mixture in the cylinder.
In accordance with the new control system, for initial freezedown,
the operator pushes a "push-to-serve" switch (hereinafter called a
"make-ready" switch) for turning the auger drive motor and, shortly
thereafter, turning the refrigerator compressor motor on. The auger
and compressor motors will remain on until the product has reaching
is proper consistency at which time the refrigerator and auger
motors turn off and an indicator lamp associated with a push-button
switch indicates to the operator that the product is ready to
serve. The amount of time that the refrigerator compressor stays
off is governed by the ambient temperature. The refrigerator is run
periodically to compensate for the heat loss through the auger
cylinder insulation. Any time that product is dispensed from the
spigot of the freezer, a timer is automatically reset to start its
timing of the refrigerator off periods after the freezer has shut
off. If no product is dispensed, the system goes automatically into
an idle cycle or energy-saving mode. After the off period, as
previously described, only the refrigerator will come on at
automatically timed intervals. By way of example and not
limitation, periodic refrigeration, such as for less than a minute,
may occur variously at 5 to 15 minute intervals, depending on
ambient temperature. The auger motor does not turn on during a
predetermined number of these intervals, typically somewhere
between 2 and 6 intervals, depending on how the timer is
programmed. After a predetermined number of these idle mode short
refrigeration intervals occur, the "make-ready" light turns on,
indicating to the operator that the freezer should be switched to
its make-ready mode if dispensing product is contemplated.
During the make-ready mode, the agitating auger and refrigerator
are operated concurrently. When auger motor wattage indicates that
the mix has reached a proper consistency for serving, the auger
motor shuts off and the idle cycles are reinstated if no product
mix is served. However, if product is dispensed at this time, the
auger drive motor and compressor drive motor will turn on and stay
on as long as the dispenser spigot is open. When the spigot is
closed, the auger drive motor and compressor will remain on for a
short minimum time or until the controller senses that the ice
cream mix product in the freezer cylinder has reached its proper
consistency. If product is dispensed after a certain number of idle
period cycles, the timer resets and starts counting over after the
freezer shuts off and the controller starts its idle cycles over
again.
How the foregoing and other more specific objects are achieved and
how the foregoing and other functional features are implemented
will now be described in reference to the drawings.
DESCRIPTION OF THE DRAWINGS
FIG. 1 is a block diagram of a soft-serve freezer and the new
control system; and
FIG. 2 is a timing diagram which is useful for describing the
invention.
DESCRIPTION OF A PREFERRED EMBODIMENT
The basic components of a soft-serve freezer are depicted in the
lower right portion of FIG. 1. These components include a
refrigerator unit designated by a block labelled as a compressor
and having the reference numeral 10. The refrigerator unit is
conventional in that it contains a compressor and a compressor
drive motor within a single sealed housing. A pair of power lines
11 and 12 supply electrical energy to the refrigerator motor.
Motors used with such compressors are typically capacitor types.
Thus, three motor input leads marked C, S and R indicate the
conventional capacitor, start and run circuits of the motor. The
capacitor switching relay is indicated by the block market 13 and
is conventional. Some parts of the refrigerator unit have been
omitted but the evaporator coil is shown and is symbolized by the
serpentine shaped line marked 14.
The ice cream mix product conditioning, freezing and dispensing
unit is designated generally by the numeral 15. This unit comprises
a metal cylinder 16 having a fluid product input port 17. A hopper,
not shown, is usually mounted above the input port for feeding
unfrozen ice cream mix or the like to the interior of cylinder 16.
Refrigeration coil 14 is in heat exchange relationship with the
exterior of cylinder 16 for the purpose of cooling the mix to
increase the viscosity. Insulation which normally surrounds the
freezer coil 14 and cylinder 16 is symbolized by the rectangle
marked 18.
Within cylinder 16 there is an auger 19 that is driven by a motor
20 through the agency of a speed reducer pulley and belt system 26.
The auger scrapes the frozen product from the interior walls of
cylinder 16 and mixes it with the remainder of the product in the
cylinder to obtain a mixture of uniform consistency or viscosity.
Consummable product is dispensed by operating the lever 21 of a
spigot 22. The power input lines to auger drive motor 20 are
designated by the reference numerals 23 and 24.
Refer now to the upper left region of FIG. 1. The power input
terminals for the dispensing freezer are identified by the numeral
30. By way of example, the power line voltage may be 240 volts ac.
Previously mentioned power lines 11 and 12 which supply the motor
in refrigerator compressor unit 10 are again identified in the
upper left region of FIG. 1. Tracing these lines will reveal that
they include a pair of relay contacts 31 which are shown in their
open circuit position in the far right region of the drawing. These
contacts are operated by means of a relay coil 32. When relay coil
32 is energized, contacts 31 close and cause the motor in
refrigerator compressor 10 to run.
One may see that previously mentioned power lines 23 and 24, which
supply the auger motor 20, are also connected directly to power
input terminals 30. One line has a magnetic circuit breaker 29 in
it. Tracing these lines reveals that they include a pair of
contacts 33 which are shown in their open state. Contacts 33 are
operated by a relay coil 34. When the contacts 33 close, of course,
auger drive motor 20 runs and turns the auger 19 for mixing the ice
cream mix in freezing cylinder 16. By way of example and not
limitation, relay coil 32 for the compressor motor and relay coil
34 for the auger drive motor may be operated with a low applied
voltage such as 24 volts. The relatively low control voltage is
obtained from the secondary winding of a step-down transformer 35
which is located in the upper left region of FIG. 1. Two conductors
36 and 37 are connected to the secondary winding terminals of
transformer 35 through one side of a double pole-double throw
switch SW1A. The other side, SW1B, will be pointed out later.
Conductor 36 leads directly to relay coil 34 and to a jumper 38
which allows relay coil 34 and the other relay coil 32 to be
energized from supply line 36. Line 37 serves as a common return
line. Relay coil 34 is in a circuit with contacts 39 that are
operated by a relay coil 41. Contacts 39 must be closed to
establish current flow from line 36 to relay coil 34 and to common
line 37. Another set of contacts 40, operated by a relay coil 42,
are in a circuit with relay coil 32. The other side, SW1B, of the
aforementioned double pole-double throw is in series with relay
coil 32. The ganged switch contacts SW1A and SW1B are closed when
it is desired to power-up or put the system in operation. When
switch SW1B is closed and contacts 40 are closed, compressor motor
relay coil 32 becomes energized by reason of current flowing from
line 38, through relay coil 32, switch SW1B, contacts 40 and to
common line 37.
Auger motor controlling contacts 39 are operated by relay coil 41
whose operating voltage, by way of example and not limitation, may
be 12 volts. The other relay coil 42, whose energization brings
about energization of relay coil 32 and the refrigerator compressor
motor, is supplied with the same voltage as relay coil 41. The
negative supply line is marked 43 and inspection of the circuit
will reveal how it makes a common connection to relay coils 41 and
42. The negative line 43 for these relays leads from a dc power
supply unit that is designated generally by the reference numeral
44. The input lines 45 to this power supply connect to the output
terminals of the secondary winding of step-down transformer 35.
Thus, by way of example, the input to power supply 44 may be 24
volts and the output may be 12 volts at the option of the circuit
designer. In any event, for present purposes one should recognize
that if line 46 running from relay coil 41 becomes energized with
+12 V dc from power supply 44, contacts 40 will close to bring
about energization of relay coil 32 which closes contacts 31 and
results in energization of the motor in refrigerator compressor
10.
To avoid the need for any further mention, observe that, as
diagrammed, there are three dc supply lines 51, 52 and 53 running
out of dc power supply 44 for supplying the same operating voltage
to the various electronic components of the control system.
The structure and functions of the controller will now be described
concurrently. Assume that liquid ice cream product mixture is being
supplied to auger cylinder 16 and that it is desired to activate
the system, that is, initiate freeze-down of the mix. The first
thing to do is manually close ganged switches SW1A and SW1B which
may be done with a common operator. Closing switch SW1A energizes
the voltage reducing and regulating power supply 44 from the
secondary of transformer 35. Closing switch SW1B enables the auger
motor and the compressor motor to be operated provided "make-ready"
switch SW4 has been closed to initiate freeze-down. Notice that
above the power supply 44 in the drawing there is an output line 54
for feeding through one or both of two switches. One of the
switches is labelled "spigot" and SW3. The other is labelled
"make-ready" and SW4. For brevity, SW3 will normally be called the
spigot switch and SW4 will be called the make-ready switch. The
spigot switch closes every time the spigot lever 21 is operated to
deliver soft-serve product out of spigot 22. The make-ready switch
SW4 is operated manually when it is necessary to bring about final
conditioning of the product in the auger cylinder in contemplation
of dispensing product. In the commercial embodiment of the freezer,
the make-ready switch is a push-button type where the push-button
is labelled "push-to-serve" which really means push to make ready
for serving. When the indicator lamp is on, the operator is
informed that the make-ready switch should be depressed momentarily
to initiate operation of the auger in contemplation of soon
dispensing mix from the spigot. In other words, the controller may
have been in its energy-saving mode for an extended period of time
during which the auger has not run. In such case, although the
product will have been constantly refrigerated, it is necessary to
run the auger for a short interval to assure uniform product
viscosity in the mixer. In the FIG. 1 block diagram, the make-ready
indicator lamp is given the numeral 55. In the commercial
embodiment, this lamp provides a red light. Another indicator lamp
56 is shown adjacent make-ready indicator lamp 55. Indicator lamp
56 provides a green light in the commercial embodiment where it is
covered by a light-transmitting shield that is labelled
"ready-to-serve." In FIG. 1 it is simply labelled "ready." When
this green light is produced by energization of lamp 56, the
operator is informed that the final make-ready interval has been
completed and that mix of proper consistency can be withdrawn from
the spigot.
As indicated earlier, proper consistency of the mix in cylinder 16
for serving is determined by sensing the wattage consumed by auger
motor 20. When consistency of the ice cream product has reached the
proper stiffness for serving, the resistive torque imposed by auger
19 on motor 20 causes the motor to reach a particular wattage input
level. Relying upon auger drive motor 20 wattage for indicating
stiffness of the ice cream mix requires simultaneous detection of
auger motor current and voltage. A current transformer 57 is
connected around power line 23 which supplies auger drive motor 20.
The leads 58 and 59 from the secondary winding of current
transformer 57 run to a rectifier that is symbolized by the block
marked 60 and labelled rectifier. This is a precision rectifier
whose output line is marked 61. This output connects to an input A
of a multiplier 62. The dc output 61 from rectifier 60 to input A
is a voltage signal that is proportional to the current flowing to
auger drive motor 20. A line leading from rectifier output line 52
to input B of the multiplier 62 supplies the multiplier with
rectified and unfiltered voltage. Hence, the dc voltage to input B
is proportional to the ac voltage that is applied to auger motor
20. A voltage compensator (volt. comp.) 66 is interposed between a
dc output of power supply 44 and input C of multiplier 62. The
compensator provides a signal to the multiplier 62 representative
of the reciprocal of phase angle .theta.. Power (P)=EI COS .theta.
or P=EI.div.1/Cos .theta. where E is the signal representative of
auger motor voltage to multiplier input A and I is the signal
representative of auger motor current to multiplier input B. The
output of the multiplier on line 64 therefore corresponds to
A.times.B.div.C. Multiplier 62, as can be seen multiplies the
voltage signal corresponding to the ac current delivered to auger
motor 20 and the dc voltage corresponding to the ac power line
voltage applied to auger motor 20 at the same time the current is
flowing. Thus, the output from multiplier 62 on line 64 is a
voltage signal corresponding to the product of the current and
voltage supplied to auger motor 20 and, hence, the wattage consumed
by the auger motor 20. Auger motor torque and wattage input
increases as the soft-serve mix freezes to a thicker viscosity.
When the wattage consumed by auger driver motor 20 reaches a preset
level, the corresponding signal on output line 64 of multiplier 62
is used to cause shutdown of the motor in refrigerator compressor
unit 10 since it, of course, began to operate when freeze-down was
initiated by closing switches SW1A and SW1B. The manner in which
the controller functions to effectuate the freezedown cycle will be
discussed in greater detail later. For the moment, it is only
necessary to be aware that during the freezedown cycle, the
compressor 10 and auger drive motor 20 will run until the mix has
reached proper consistency and then the system will go into its
energy-saving mode wherein the compressor will remain off for
substantial time intervals and then turn on for short intervals to
keep the mix in a satisfactorily viscous condition.
Various operating conditions will be examined before proceeding
with the description of the controller's construction. Attention is
invited to the FIG. 2 timing diagram. In this diagram, the timing
functions of the auger motor and refrigerator motor are labelled
correspondingly. Observe in FIG. 2 that, during the freezedown
cycle which was just briefly discussed, the auger drive motor 20
will turn on in response to the momentary make-ready switch SW4
being operated and a few seconds later the refrigerator motor will
turn on. Both will run for that period of time which is required to
bring up the soft-serve ice cream mix in the auger cylinder 16 to
the proper viscosity or consistency. During this time, make-ready
indicator lamp 55 will be energized for displaying a red indication
to the operator. When the desired consistency is reached, as a
result of the wattage consumption of the auger motor 20 exceeding
set point, the auger motor turns off and a few seconds later, the
refrigerator motor turns off. As the legend above the auger motor
timing diagram reveals, ready lamp 56 is then switched to green and
it remains green for a definite amount of time, indicating that the
mix is in condition for serving during that time as will be more
fully explained later. The turn-off time of auger motor 20 furing
the initial freezedown cycle is indicated in FIG. 2 by the numeral
70 and the slightly delayed turn-off time of the refrigerator motor
is indicated by the numeral 71. When these motors turn off,
assuming no frozen mix is withdrawn through the spigot, the system
goes into its idle or energy-saving mode. In this mode, the
refrigerator motor is initially off for a time interval marked 72
and then it turns on for a typical time interval 73 which is
followed by off intervals such as those marked 74, 76, 78 and 80
between which there are short refrigerator "on-time" intervals 75,
77 and 79. As will be explained, the controller is provided with
means for permitting the frequency and durations of the off and on
periods to be selected. Moreover, the number of on-off cycles such
as 72,73 and 74,75 and 76,77 before which the auger motor must be
commanded to run may be selected. In this illustrative example,
during the first three cycles comprised of off-time intervals 72,73
and 74,75 and interval 76 the mix is assumed to remain in a
ready-to-serve condition. In accordance with the invention, and by
means of which will be described in greater detail later, the
amount of time that the compressor stays off is governed by the
ambient temperature. By way of example and not limitation, the off
periods such as the one marked 72 might have a fifteen-minute
duration if the ambient temperature were 70.degree. F. and have a
shorter duration such as five minutes if the ambient temperature is
high such as near 100.degree. F. The off periods, are, of course,
shorter if the ambient temperature is high, since a greater heat
gain by the mix in the cylinder 16 through the freezer insulation
from the environment can be expected under high ambient temperature
conditions.
The refrigerator on-time periods such as the one marked 73, during
the idle or energy-saving mode, are governed strictly by a
selectable timing function independently of ambient temperature.
During the first on-off cycles, such as to the end of off period
76, the green ready light 56 will remain on to indicate to the
operator that the mix is ready to serve. The interval during which
the green lamp remains energized is indicated on the diagram.
Still referring to FIG. 2, if no mix is dispensed during a
predetermined number of compressor off-on cycles, it is assumed
that the auger 19 should be driven to make the consistency of the
mix in freezer cylinder 16 uniform and of proper viscosity. Thus,
by means which will be explained, the controller effectuates
energization of the red make-ready lamp 55 to indicate to the
operator that make-ready switch SW4 should be depressed when
dispensation of mix from the spigot 22 is contemplated. Operation
of this make-ready switch will cause the auger motor 20 and the
refrigerator compressor 10 to be energized and, if no mix were
dispensed, the auger motor and compressor would run until proper
consistency of the mix is reached, resulting in the torque on the
motor increasing and its wattage increasing to bring about
termination of compressor and auger operation as previously
mentioned. At any time that product is dispensed, however, the
timer, to be discussed later, is automatically reset to start its
timing of the off periods of the refrigerator after it shuts off.
In fact, if product is dispensed after only two idle period or
energy saving cycles, the timer will reset and renew the off-on
timing cycles. Whenever the spigot 22 is opened to dispense
product, or the make-ready switch SW4 is operated, both the auger
drive motor 20 and the refrigerator compressor 10 turn on. As will
be seen later when the controller structure is further described,
both will stay on as long as the spigot is open. When the spigot is
closed, the auger drive motor 20 and the compressor 10 will remain
on for a minimum of a certain number of seconds, such as twelve, or
until the wattage dependent consistency monitor senses that the
product has reached its proper consistency. FIG. 2 exemplifies at
points marked 81 and 81' where the motors would have shut off
because the set point wattage was reached but both of the
compressor and auger motor turned on again because the spigot was
opened to withdraw product. A detailed description of the
structural and functional features of the circuitry in FIG. 1 will
now be resumed.
Assume that the system has been inactive and is to be powered-up
for freezedown. The first thing the operator does is close the
ganged switches SW1A and SW1B for energizing power supply 44 and
closing the circuits for the compressor control relay 34 and auger
motor relay 32, although these motors do not start as yet. When the
power goes on, the red make-ready lamp 55 goes on for reasons which
will be described later. The lamp indicates to the operator that
the previously mentioned make-ready switch SW4, shown adjacent
power supply 44, should be closed. When SW4 is closed, a signal is
delivered through it and by way of a line 85 to a latch circuit
which is symbolized by the block marked 86. The latch circuit is
implemented with electronic elements but is functionally equivalent
to a latching relay. One of the output lines 87 from the latch
circuit is a control signal input to a switching circuit 88 which
is identified an an "output auger" circuit since it is involved in
causing auger motor 20 to run. When the make-ready SW4 is closed
and the latch circuit provides a signal to the output auger circuit
88, the latter switches and applies a positive voltage to line 46,
thereby causing the relay coil 41 to be energized. This closes
contacts 39 for permitting the higher power level relay coil 34 to
be energized. Relay coil 34 then closes contacts 33 and causes
auger motor 20 to be energized from power lines 23 and 24. Auger 19
is now agitating the mix in freezing cylinder 16. Output auger
circuit 88 provides a signal by way of line 89 to a time delay
circuit which is represented by a block having that legend and the
reference numeral 90. Time delay circuit 90 is indicated to be a
three-second timer but it can be set for other time periods. The
purpose of the time delay circuit is to cause the motor in
refrigerator compressor 10 to turn on a short time after the auger
motor turns on and to turn off a short time after the auger motor
turns off. Thus, switching transients are not reflected as
extensively through the entire control system. In any event, after
the short time delay interval imposed by timer 90 has expired, it
provides a signal by way of its output line 91 to a circuit that
has the legend "output compressor" and is identified by the numeral
92. Output compressor circuit 92 is a switching circuit involved in
causing the refrigerator 10 motor to run and is enabled by the
signal from the time delay circuit 90. Circuit 92 responds by
supplying a positive voltage by way of line 47 to compressor motor
relay coil 42. This causes contacts 40 to close and energize relay
coil 32. When the latter coil is energized, line contacts 31 close
to energize the motor in refrigerator compressor unit 10 by way of
power lines 11 and 12. The motors for the auger and compressor are
now running concurrently. The viscosity of the mix in cylinder 16
is now increasing. The current to the auger motor 20 is being
sensed by way of current transformer 57 and the multiplier 62 is
producing the output signal on line 64 which is representative of
the wattage being supplied to auger drive motor 20 as was
previously explained.
The signal on line 64 representative of auger motor wattage is an
input to a block labelled consistency adjustment and having the
reference numeral 95. Block 95 is basically an analog signal
comparator. It is supplied with a positive dc voltage that can be
raised or lowered by adjusting potentiometers 96, 97 and 99.
Potentiometers 96 and 97 are sized such that they can provide a
larger change in voltage, acting as a coarse adjustment. Switch 98
can be switched to put potentiometer 96 in the circuit to set the
consistency adjustment circuit 95 for making shakes or to put
potentiometer 97 in the circuit for obtaining a suitable mix
consistency or viscosity for making cones.
The signal from the multiplier on line 64 is fed to the negative
side of the comparator. The signal from the circuit including
potentiometer 99, 96 or 97 and switch 98 is fed to the positive
side of the comparator. When the signal on line 64 becomes greater
than that being supplied through the switch and potentiometer
circuit the output 100 of the comparator switches to ground. Each
switching spike which occurs as the product approaches consistency
causes the LED 106 to flash. This aids in setting the control to
the desired consistency cutout point. Moreover, it is intended that
latch circuit 86 should not open to cause the auger and
refrigerator motors to stop until a predetermined number of spikes
occur. This is accomplished with the averaging circuit that is
represented by the block marked 101. The averaging circuit 101
smooths the spikes, which actually result from the auger motor
encountering short term variations in load. For instance, the mix
in the cylinder 16 may be more frozen or solidified in some zones
than in others so that auger 19 encounters variable counter-torque
as it rotates or there may be imperfections in the drive system
that cause load variations.
The smooth analog output signal from averaging circuit 101 is fed
by way of a line 102 back to latch 86 which is basically a
comparator. If the wattage being consumed by the auger drive motor
20 corresponds to a viscosity below a set point, the output signal
on line 102 will be below a threshold level. Hence, the latch 86
will remain set. As consistency of the mix increases, however, the
output signal on line 102 from the averaging circuit will
eventually exceed the set point and the threshold level of the
latch circuit 86 in which case the latch circuit will be switched
to turn off. The signal state on output line 87 of latch circuit 86
then changes and the output auger circuitry 88 responds by
deenergizing relay 41 to bring about deenergization of the auger
drive motor 20. This corresponds, for example, to the point in time
marked 70 in FIG. 2. The previously mentioned three-second time
delay 90 in FIG. 1 responds to a signal on line 89 indicative of
the output auger or switching circuit 88 having changed state by
initiating another three-second time delay period. At the end of
this period the time delay operates the output compressor switching
circuit 92, that is, the latter effectuates deenergization of the
refrigerator compressor motor control relay 42 to thereby terminate
refrigeration. This corresponds to the point in time marked 71 in
FIG. 2. The system now goes into its power-saving mode as will be
described shortly hereinafter.
Before such description, some collateral matters will be discussed.
Notice, for example, that next to latch circuit 86 there is a block
marked "minimum (min.) run timer" which has the reference numeral
103. In the commercial embodiment, by way of example and not
limitation, this timer measures a twelve-second interval. Its
purposes are to make sure that whenever the motors are energized
they will run for at least twelve seconds to pass out of their
starting current interval and to agitate and assure a consistently
blended mix before starting to sense its consistency. Thus, the
minimum run timer 103 responds to the latch circuit 86 being set by
providing a signal that results in the consistency adjustment
circuit maintaining an output signal that is below the set point so
that the signal feeding through the averaging circuit 101 remains
for 12 seconds.
Another factor to be discussed before discussing the power-saving
mode is the matter of controlling and using the information
provided by the indicator lamps 55 and 56. The manner in which the
system is powered up and operated until initial set point
consistency of the mix is obtained has just been described. When
power first comes on this condition is sensed by a start-up lamp
set circuit symbolized by the block marked 108. It has a power
input and a signal output line 109 which leads to a block 110 that
is labelled "make-ready lamp" and is essentially a flip-flop
circuit. Flip-flop circuit 110 has output conductors 111 leading to
lamp driver circuits represented by the block marked 112. When
power first comes on, start-up lamp set circuit 108 provides an
input signal to the flip-flop circuitry in block 110 to cause the
output state of the flip-flop to be that which results in the red
make-ready lamp 55 going on. It will go on even before the
momentary make-ready switch SW4 has been turned on to initiate mix
freezing and agitation. The fact that the make-ready lamp 55 is on
suggests to the operator that the make-ready switch SW4 should be
operated. Thus, the start-up lamp set circuit 108 is a way of being
positive that the red make-ready lamp 55 will go on when power is
first turned on.
Means are provided for turning off the make-ready lamp 55 and
turning on the green ready lamp 56 when set point consistency of
the mix has been attained. An "output auger" detector circuit
symbolized by the block marked 113 is involved in this function. It
detects whether or not the auger motor 20 is energized. It has a
signal input line 114 fed from an output of the output auger
switching circuit 88. The output auger detector circuit 113 detects
when the auger is on and when it shuts off upon set point being
reached, there is a signal level change on line 14 which causes the
auger output detector 113 to deliver a signal by way of its output
line 115 to the make-ready lamp or flip-flop circuit 110. This
signal changes the output state of the flip-flop. The output state
change causes the lamp driver circuit 112 to turn off the red
make-ready lamp 55 and turn on green ready lamp 56. The operator is
now apprised visually that the mix is in a ready-to-serve
condition. The auger output detector circuit 113 and start-up lamp
set circuit 108 are involved in controlling the lamp when the
system is in the power-up mode. They are also involved at any time
that the auger motor and refrigerator motor are switched on by
operation of make-ready switch SW4 or spigot switch SW3 and the
make-ready light 55 is on prior to activating a switch. The lamps
are controlled by other means during the times when the system is
in the electrical energy-saving mode which will now be
described.
As explained earlier in reference to the FIG. 2 timing diagrams,
when set point consistency is reached for the first time, the auger
motor and the refrigerator motor turn off at the points in time
marked 70 and 71, respectively. If no mix product is withdrawn
through spigot 22, that is, if spigot switch SW3 is not operated,
the system will go into its energy-saving mode wherein it only uses
that minimum of electric power which is required to keep the mix at
a temperature that will result in it having a reasonably high
viscosity but not necessarily uniform viscosity through the volume
of the cylinder 16. In other words, during the energy-saving mode
only the refrigerator compressor will turn on for short intervals
between long intervals and the auger drive motor will not run
during that time unless it is commanded to do so by the operator.
As previously mentioned in connection with FIG. 2, the first
time-delay period following proper mix consistency having been
reached is indicated by the numeral 72. It is followed by short
intervals such as the one marked 73 during which the refrigerator
motor is turned on for a short interval. How this is done will now
be discussed in reference to FIG. 1.
The off time of the refrigerator compressor 10 during the
energy-saving mode depends on the ambient temperature. The on time
is governed by a measured time interval and remains constant at
whatever time it is set.
The ambient temperature is sensed by an electronic
temperature-to-voltage converter which is symbolized by the block
marked 120 in the left region of FIG. 1. This is a commercially
available circuit element. It provides an analog signal on its
output line 121 which corresponds in magnitude to prevailing
ambient temperature. The slope of the temperature versus output
signal amplitude is settable by adjusting a potentiometer 119. A
typical contemplated ambient temperature range that must be taken
into account for a soft-serve freezer such as is here under
consideration is 70.degree. F. to 110.degree. F.
The analog output signal from the temperature converter 120 is fed
by way of line 121 to a voltage-to-time converter represented by
the block marked 122. The converter circuit 122 is basically a
voltage controlled oscillator which outputs pulses on line 123 at a
rate which increases and decreases in correspondence with ambient
temperature. The objective is to use the pulse rate as a measure of
time to have the refrigerator motor off cycles be shorter as
ambient temperature rises to compensate for the greater loss
through the refrigerator coil insulation 18 as ambient temperature
increases.
The quiescent or refrigerator off time periods are determined with
a pulse-counting circuit which is symbolized by the block marked
124 and which, for the sake of illustration and not limitation, is
designated as a divide-by-10 counter. By way of example, if the
output pulse rate from the converter 122 is one pulse every half
minute, dividing by ten or counting every tenth pulse would result
in an output signal from divide-by-ten counter every 5 minutes.
This might correspond roughly to an ambient temperature of about
70.degree. F. and a measured time period of about 15 minutes.
Each time a count representative of an off time interval of a
certain number of minutes corresponding to prevailing temperature
terminates, a signal is sent from divide-by-ten counter 124 by way
of a line 125 to a compressor run timer represented by the block
marked 126. Timer 126 may be based on a type 556 integrated circuit
timer, not shown. When it receives a trigger signal over line 125
it changes the state of its output which results in a signal being
delivered over output line 127 to time-delay circuit 90. The signal
is coupled through the time delay circuit to the output compressor
circuit 92 which then effectuates grounding of relay coil line 47
to energize coil 42 and cause the refrigerator compressor motor to
turn on. The length of time that the compressor remains on during
this and ensuing energy-saving mode cycles is determined by
compressor run timer 126. By way of example and not limitation,
timer 126 may keep the refrigerator compressor on for about 50
seconds although this is a matter of choice and depends on the
parameters of a particular freezer system. The refrigerator on time
is adjustable but constant for any particular adjustment. Selection
of adjustment of the on-time interval can be made with a
potentiometer 128 which is in a time constant circuit, not fully
shown, associated with the timer 126. Typical refrigerator run
intervals during the energy-saving mode are illustrated by the
intervals marked 73, 75 77 and 79 in FIG. 2. At the end of each
refrigerator on period, compressor output circuit 92 sends a reset
signal by way of line 129 to the pulse counter 124 to zero it to
begin timing out the next refrigerator off period.
If the mix in cylinder 16 is just refrigerated cyclically during
the energy-saving mode and is not agitated by the auger, eventually
the mix is likely not to have uniform viscosity throughout its
volume. The controller provides for indicating to the operator that
the mix should be agitated and refrigerated or made ready before
any mix is dispensed from spigot 22. Another counter symbolized by
the block marked 130 is provided for giving the operator this
indication. Counter 130 bears the legend, divide by 3, but it
should be understood that this is a programmable counter that might
be set to divide by 2 through 6, for instance. Counter 130 has an
input line 131 from counter 124. Considering that counter 130 is a
divide-by-3 counter for the sake of example, it will respond to
counting three of the refrigerator off-time periods that are
measured by counter 124 by producing an output signal at that time
on a line 132. Line 132 is coupled to the make-ready lamps or
flip-flop circuit 110. When a signal is received over line 132, the
flip-flop circuit changes state and refelcts this change through
its output line 111. The result is that the green ready lamp 56
which has been on, is turned off. At the same time, the red
make-ready lamp 55 is turned on. This indicates to the operator
that make-ready switch SW4 should be closed to effectuate operation
of the compressor and auger to assure that the mix in cylinder 16
has a high enough and uniform enough viscosity before any mix is
dispensed through the spigot 22.
If the operator does not contemplate having to serve any customer,
the operator can simply forego actuating the make-ready switch SW4
until an impending sale. The refrigerator long off-time and short
on-time periods will continue to occur cyclically and no power will
unnecessarily be consumed by the auger motor.
If, dispensation of product is contemplated, the operator will
assuredly actuate make-ready switch SW4 to cause refrigeration and
auger agitation of the mix. At any time that mix is dispensed, of
course, the compressor and auger immediately turn on as a result of
spigot switch SW3 adjacent power supply 44 becoming closed by
reason of spigot lever 21 having been actuated. This results in the
latch circuit 86 performing the functions which were previously
described. Moreover, the consistency detecting multiplier 62,
consistency adjustment device 95 and averaging circuit 101 becomes
effective to turn on the compressor and auger motor and to turn
them off in response to the consistency set point having been
reached.
As indicated, the red make-ready lamp comes on if there have been
three consecutive refrigerator off or idle period cycles. If
product is dispensed after two idle period cycles, for instance,
the divide-by-ten counter 124 will reset and start counting over
after the refrigerator compressor shuts off and starts its idle
cycles over again. The divide-by-three counter 130 also resets in
response to a reset signal by way of line 133 from auger output
circuit 88. Then the divide-by-three counter starts counting for
another three cycles in this illustrative embodiment.
In a number of instances in this description numerical values were
used for the sake of clarity that results from using concrete
numbers. It should be understood, however, that the operating
parameters are selectable. They will be chosen in conformity with
the ambient temperatures, physical characteristics of the
refrigerating system and the auger mixer and the general
environmental conditions under which a particular soft-serve
freezer is intended to operate.
Although a preferred embodiment of the invention has been described
in considerable detail, such description is intended to be
illustrative, rather than limiting, for the invention may be
variously embodied and is to be limited only by interpretation of
the claims which follow.
* * * * *