U.S. patent number 3,769,809 [Application Number 05/145,130] was granted by the patent office on 1973-11-06 for control apparatus for an ice maker.
This patent grant is currently assigned to Whirlpool Corporation. Invention is credited to John B. Lyman, James M. Robinson.
United States Patent |
3,769,809 |
Robinson , et al. |
November 6, 1973 |
**Please see images for:
( Certificate of Correction ) ** |
CONTROL APPARATUS FOR AN ICE MAKER
Abstract
An ice maker of the type comprising a freezing cylinder with the
coils of an evaporator disposed circumjacent thereto, an auger
rotatable within the freezing cylinder and a bin for receiving and
storing an ice product produced by the ice maker has a control
apparatus adapted to control the operation of an auger motor
rotating the auger so that the auger motor operates whenever the
accumulation of ice within the storage bin is below a preselected
level and the temperature of a compressor suction line connected to
the evaporator is above a first preselected value and discontinuing
the operation of the auger motor whenever either the accumulation
of ice within the bin is above the preselected level or the
temperature of the compressor suction line at a point adjacent to a
compressor is below a second preselected value less than the first
preselected value. In that manner, the production of ice is
regulated in accordance with the demand for ice and is discontinued
in the event of excessive flood back to the compressor. The control
apparatus also discontinues operation of the compressor in the
event the auger motor becomes overloaded, and a clean cycle switch
enables operation of the auger motor without simultaneously
operating the compressor to facilitate cleaning operations.
Inventors: |
Robinson; James M. (White Bear
Lake, MN), Lyman; John B. (Bloomington, MN) |
Assignee: |
Whirlpool Corporation (Benton
Harbor, MI)
|
Family
ID: |
22511726 |
Appl.
No.: |
05/145,130 |
Filed: |
May 20, 1971 |
Current U.S.
Class: |
62/137; 62/227;
62/354 |
Current CPC
Class: |
F25C
1/147 (20130101); F25C 5/187 (20130101) |
Current International
Class: |
F25C
1/12 (20060101); F25C 5/00 (20060101); F25C
5/18 (20060101); F25C 1/14 (20060101); F25c
001/14 () |
Field of
Search: |
;62/137,135,227,354,303 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Wayner; William E.
Claims
We claim as our invention:
1. In an ice maker of the type comprising a freezing cylinder
having means forming passageways of an evaporator disposed
circumjacent thereto, the evaporator being part of a refrigeration
circuit which also includes a condenser and a compressor driven by
an electric compressor motor and having a suction line connected
with the evaporator, an auger rotatable within the freezing
cylinder and being driven by an electric auger motor, bin means for
receiving and storing an ice product produced by the ice maker, and
control circuit means controlling the operation of the ice maker,
the improvement wherein said control circuit comprises:
input terminals for connection with an electric supply; bin sensing
means for sensing the level of ice in said bin; suction line
sensing means for sensing the temperature of the compressor suction
line;
control circuit means for controlling the operation of said auger
motor and being connected with said input terminals, said circuit
means including a single single-pole switch operated by said bin
sensing means and said suction line sensing means for operating
said auger motor whenever the accumu-lation of ice within the bin
is below a preselected level and the temperature of the compressor
suction line adjacent to the compressor is above a first
preselected value and discontinuing the operation of the auger
motor whenever either the accumulation of ice within the bin is
above the preselected level or the temperature of the compressor
suction line adjacent to the compressor is below a second
preselected value less than the first preselected value.
2. In an ice maker, a control circuit as defined in claim 1 and
further characterized by:
said control circuit means comprising a series circuit connected
with said input terminals and including the auger motor and said
switch, said switch closing whenever the accumulation of ice within
the bin is below the preselected level and the temperature of the
compressor suction line adjacent to the compressor is above the
first preselected value and opening whenever either the
accumulation of ice within the bin is above the preselected level
or the temperature of the compressor suction line adjacent to the
compressor is below the second preselected value.
3. In an ice maker, a control circuit as defined in claim 2, said
series circuit further comprising a normally closed thermal
overload switch connected in series with the auger motor and
opening whenever the auger motor is overloaded.
4. In an ice maker of the type comprising a freezing cylinder
having means forming passageways and an evaporator disposed
circumjacent thereto, the evaporator being part of a refrigeration
circuit which also includes a condenser and a compressor driven by
an electric compressor motor and having a suction line connected
with the evaporator, an auger rotatable within the freezing
cylinder and being driven by an electric auger motor, bin means for
receiving and storing an ice product produced by the ice maker, and
control circuit means controlling the operation of the ice maker,
the improvement wherein said control circuit comprises:
input terminals for connection with an electric supply; bin sensing
means for sensing the level of ice in said bin; suction line
sensing means for sensing the temperature of the compressor suction
line;
control circuit means for controlling the operation of said auger
motor and being connected with said input terminals, said circuit
means operating said auger motor whenever the accumulation of ice
within the bin is below a preselected level and the temperature of
the compressor suction line adjacent to the compressor is above a
first preselected value and discontinuing the operation of the
auger motor whenever either the accumulation of ice within the bin
is above the preselected level or the temperature of the compressor
suction line adjacent to the compressor is below a second
preselected value less than the first preselected value,
said control circuit means comprising a series circuit connected
with said input terminals and including the auger motor and control
switch means operated by said bin sensing means and said suction
line sensing means for closing whenever the accumulation of ice
within the bin is below the preselected level and the temperature
of the compressor suction line adjacent to the compressor is above
the first preselected value and opening whenever either the
accumulation of ice within the bin is above the preselected level
or the temperature of the compressor suction line adjacent to the
compressor is below the second preselected value,
said series circuit further comprising a noramally closed thermal
overload switch connected in series with the auger motor and
opening whenever the auger motor is overloaded,
thermostatic safety switch means sensing the temperature of the
evaporator and closing whenever the temperature of the evaporator
is above a first preselected value and opening whenever the
temperature of the evaporator is below a second preselected value
less than said first preselected value, and
relay switch means including a relay coil and a first set of
normally opened contacts, said relay coil being connected in
parallel with said auger motor, and said first set of normally
opened contacts being connected in parallel with said safety switch
means,
whereby whenever said thermal overload switch opens, said first set
of relay contacts opens so that said auger motor means may not be
restarted unless said safety thermostatic switch means are
closed.
5. In an ice maker, a control circuit as defined in claim 4, and
further characterized by:
said relay switch means including a second set of normally opened
contacts connected with the compressor motor and closing to operate
the compressor motor whenever said relay coil is energized and
opening whenever said relay coil is deenergized,
whereby said compressor will not be operated in the event said
thermal overload switch is opened.
6. In an ice maker, a control circuit as defined in claim 5 and
further comprising:
manually operable switch means having a first set of normally
closed contacts, a second set of normally closed contacts and a set
or normally opened contacts, all of said sets of contacts being
mechanically innerconnected for operation in unison,
said first set of normally closed contacts being connected in a
series circuit comprising said control switch means, said
thermostatic safety swtich means, said auger motor overload switch
means and the auger motor,
said second set of normally closed contacts being connected in
series with said relay coil, and
said set of normally opened contacts being connected in parallel
with said control switch means, said safety thermostatic switch
means, and said first set of normally closed contacts.
7. An apparatus for controlling the operation of an ice maker of
the type having means forming passageways of an evaporator disposed
circumjacent thereto, the evaporator being part of a refrigeration
circuit which also includes a condenser and a compressor having a
suction line connected with the evaporator, an auger rotatable
within the freezing cylinder and bin means for receiving and
storing an ice product produced by the ice maker, the control
apparatus comprising:
input terminal means for connection with an electric supply;
an electric motor for rotating the auger and including a thermal
overload switch for interrputing the operation of the auger motor
when the same becomes overloaded;
an electric compressor motor for operating the compressor; and
control means connected with said input terminal means, said auger
motor, said thermal overload switch and said compressor motor and
including switch means simultaneously operating said auger motor
and said compressor motor and discontinuing the operation of said
compressor motor whenever said overload switch opens to interrupt
the operation of said auger motor.
8. A control apparatus as defined in claim 7 wherein said switch
means comprises:
relay switch means including a relay coil and a set of normally
opened contacts, said relay coil being connected in parallel with
said auger motor and said set of relay contacts being connected in
series with said compressor motor,
whereby whenever said thermal overload switch opens, said relay
coil is deenergized to open said set of relay contacts to
discontinue the operation of said compressor motor.
9. A control apparatus as defined in claim 8, wherein said switch
means further comprises:
manually operable switch means having a first set of normally
closed contacts, a second set of normally closed contacts and a set
of normally opened contacts, all of said sets of contacts being
mechanically innerconnected for operation in unison,
said first set of normally closed contacts being connected in a
series circuit comprising said auger motor and said thermal
overload switch,
said second set of normally closed contacts being connected in
series with said relay coil, and
said set of normally opened contacts being connected in parallel
with said first set of normally closed contacts, whereby whenever
said set of normally opened contacts are closed, said relay coil is
deenergized to prevent the operation of said compressor motor,
while enabling the operation of said auger motor separately of said
compressor motor.
10. In an ice maker of the type comprising a freezing cylinder
having means forming passageways and an evaporator disposed
circumjacent thereto, the evaporator being part of a refrigeration
circuit which also includes a condenser and a compressor driven by
an electric compressor motor and having a suction line connected
with the evaporator, an auger rotatable within the freezing
cylinder and being driven by an electric auger motor, bin means for
receiving and storing an ice product produced by the ice maker, and
control circuit means controlling the operation of the ice maker,
the improvement wherein said control circuit comprises:
input terminals for connection with an electric supply; bin sensing
means for sensing the level of ice in said bin;
suction line sensing means for sensing the temperature of the
compressor suction line;
control circuit means for controlling the operation of said auger
motor and being connected with said input terminals, said circuit
means operating said auger motor whenever the accumulation of ice
within the bin is below a preselected level and the temperature of
the compressor suction line adjacent to the compressor is above a
first preselected value and discontinuing the operation of the
auger motor whenever either the accumulation of ice within the bin
is above the preselected level or the temperature of the compressor
suction line adjacent to the compressor is below a second
preselected value less than the first preselected value,
said control circuit means comprising a series circuit connected
with said input terminals and including the auger motor, and
control switch means comprising a single single-pole switch
operated by said bin sensing means and said suction line sensing
means for closing whenever the accumulation of ice within the bin
is below the preselected level and the temperature of the
compressor suction line adjacent to the compressor is above the
first preselected value and the temperature of the evatorator is
above a preselected temperature.
11. In an ice maker of the type comprising a freezing cylinder
having means forming passageways and an evaporator disposed
circumjacent thereto, the evaporator being part of a refrigeration
circuit which also includes a condenser and a compressor driven by
an electric compressor motor and having a suction line connected
with the evaporator, an auger rotatable within the freezing
cylinder and being driven by an electric auger motor, bin means for
receiving and storing an ice product produced by the ice maker, and
control circuit means controlling the operation of the ice maker,
the improvement wherein said control circuit comprises:
input terminals for connection with an electric supply; bin sensing
means for sensing the level of ice in said bin; suction line
sensing means for sensing the temperature of the compressor suction
line;
control circuit means for controlling the operation of said auger
motor and being connected with said input terminals and circuit
means operating said auger motor whenever the accumulation of ice
within the bin is below a preselected level and the temperature of
the compressor suction line adjacent to the compressor is above a
first preselected value and discontinuing the operation of the
auger motor whenever either the accumulation of ice within the bin
is above the preselected level or the temperature of the compressor
suction line adjacent to the compressor is below a second
preselected value less than the first preselected value,
said control circuit means comprising a series circuit connected
with said input terminals and including the auger motor and control
switch means operated by said bin sensing means and said suction
line sensing means for closing whenever the accumulation of ice
within the bin is below the preselected level and the temperature
of the compessor suction line adjacent to the compressor is above
the first preselected value and opening whenever either the
accumulation of ice within the bin is above the preselected level
or the temperature of the compressor suction line adjacent to the
compressor is below the second preselected value, and
relay switch means including a relay coil and a first set of
normally opened contacts, said relay coil being connected in
parallel with said auger motor, and said first set of normally
opened contacts being connected between said compressor motor and
said input terminals.
12. In an ice maker of the type comprising a freezing cylinder
having means forming passageways and an evaporator disposed
circumjacent thereto, the evaporator being part of a refrigeration
circuit which also includes a condenser and a compressor driven by
an electric compressor motor and having a suction line connected
with the evaporator, an auger rotatable within the freezing
cylinder and being driven by an electric auger motor, bin means for
receiving and storing an ice product produced by the ice maker, and
control circuit means controlling the operation of the ice maker,
the improvement wherein sqid control circuit comprises:
input terminals for connection with an electric supply;
control circuit means for controlling the operation of said auger
motor and being connected with said input terminals, said circuit
means operating said auger motor whenever the accumulation of ice
within the bin is below a preselected level and the temperature of
the compressor suction line adjacent to the compressor is above a
first preselected value and discontinuing the operation of the
auger motor whenever either the accumulation of ice within the bin
is above the preselected level or the temperature of the compressor
suction line adjacent to the compressor is below a second
preselected value less than the first preselected value,
said control circuit means comprising a series circuit connected
with said input terminals and including the auger motor and control
switch means closing whenever the accumulation of ice within the
bin is below the preselected level and the temperature of the
compressor suction line adjacent to the compressor is above the
first preselected value and opening whenever either the
accumulation of ice within the bin is above the preselected level
or the temperature of the compressor suction line adjacent to the
compressor is below the second preselected value, and
a thermostatic switch having a temperature sensing bulb element
disposed in the bin and a capillary tube innerconnecting said bulb
with means controlling the condition of said control switch means,
wherein said capillary tube has a portion disposed adjacent to and
sensing the temperature of the compressor suction line at a
location adjacent the compressor.
13. In an ice maker of the type comprising a freezing cylinder
having means forming passageways of an evaporator disposed
circumjacent thereto, the evaporator being part of a refrigeration
circuit which also includes a condenser and a compressor driven by
an electric compressor motor and having a suction line connected
with the evaporator, an auger rotatable within the freezing
cylinder and being driven by an electric auger motor, bin means for
receiving and storing an ice product produced by the ice maker, and
control circuit means controlling the operation of the ice maker,
the improvement wherein said control circuit comprises:
input terminals for connection with an electric supply;
control circuit means for controlling the operation of said auger
motor and being connected with said input terminals, said circuit
means including a single switch for operating said auger motor
whenever the accumulation of ice within the bin is below a
preselected level and the temperature of the compressor is above a
first preselected value and discontinuing the operation of the
auger motor whenever either the accumulation of ice within the bin
is above the preselected level or the temperature of the compressor
suction line adjacent to the compressor is below a second
preselected value less than the first preselected value;
said control circuit means comprising a series circuit connected
with said input terminals and including the auger motor and said
switch, said switch closing whenever the accumulation of ice within
the bin is below the preselected level and the temperature of the
compressor suction line adjacent to the compressor is above the
first preselected value and opening whenever either the
accumulation of ice within the bin is above the preselected level
or the temperature of the compressor suction line adjacent to the
compressor is below the second preselected value;
said switch comprising a thermostatic switch having a temperature
sensing bulb element disposed in the bin and a capillary tube
innerconnecting said bulb element with means controlling the
condition of said control switch means, wherein said capillary tube
has a portion disposed adjacent to and sensing the temperature of
the compressor suction line at a location adjacent the compressor.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention generally relates to an auger-type ice making
apparatus, and more particularly refers to a control circuit for
controlling the operation of an auger-type ice maker in response to
demand for ice and in a manner to prevent damage to the
appartus.
While the present invention is described in reference to a specific
auger-type ice maker including separate harvest and compression
augers and being described in several copending applications
commonly assigned with this application, the principles of the
present invention have general utility with most auger-type ice
machines.
2. Description of the Prior Art
An auger-type ice maker generally comprises a freezing chamber
having an interior cylindrical wall for cooperation with the
flights of an auger rotatable within the chamber in a manner to
harvest a film of ice which forms on the interior wall. The coils
or passageway means of an evaporator are circumjacently disposed
about the freezing chamber and form part of a refrigeration system,
which also includes a compressor, a condenser, an expansion valve
and conduits interconnecting the components and including a suction
line between the evaporator and the compressor. An ice product
produced by the ice maker may be tranported to and stored in an
appropriate storage bin for utilization by a consumer.
In order to prevent damage to an auger motor driving the rotatable
auger, it is desirable to prevent start up of the motor in the
event the freezing chamber is clogged with accumulated ice.
Further, an accumulation of ice within the freezing chamber during
operation of the ice maker may overload the auger motor, in which
event the operation of the auger motor is discontinued. To
faciltate thawing of the ice maker unit so that the production of
ice may be resumed, it is desirable to discontinue the operation of
the compressor and the condenser fan whenever the auger motor cuts
out due to an overload.
Heretofore, ice makers have been adapted to operate in response to
demand for ice within a storage bin, however, those ice makers have
not included controls for preventing operation of the machine
whenever the inlet water supply is interrupted, during a "spin out"
condition when the system is full of ice but no new ice is being
properly transferred from the freezing chamber or in the event of
excessively low temperature operating conditions.
Also, in order to facilitate the cleaning of the freezing chamber,
it is desirable to operate the auger motor without simultaneously
operating the compressor motor, thereby to agitate a cleaning
fluid, such as an citric acid solution, within the freezing
chamber.
SUMMARY OF THE INVENTION
In accordance with the principles of the present invention, an
auger-type ice maker comprising a freezing cylinder having means
forming passageways of an evaporator disposed circumjacent thereto,
with the evaporator being part of a refrigeration circuit which
also includes a condenser and a compressor driven by an electric
compressor motor and having a suction line connected to the
evaporator, an auger rotatable within the freezing cylinder and
being driven by an electric motor, a bin for receiving and storing
an ice product produced by the ice maker, has a control apparatus
adapted to operate the auger motor whenever there is a demand for
ice within the bin and the temperature of the compressor suction
line is above a first preselected value and discontinuing the
operation of the auger motor whenever either the bin is full or the
temperature of the compressor suction line is below a second
preselected value less than that of the first preselected value.
Thus, the ice maker is not operated to produce ice in the event
frost accumulates on the compressor suction line in an area
adjacent the compressor, which condition will result from an
excessive flood back of the refrigerant to the compressor. The
excessive flood back may be due to a lack of inlet water being
supplied to the freezing chamber, a "spin out" condition wherein
the system is full of ice but no new ice is being properly
transferred from the freezing chamber or an excessively low
temperature operating condition.
Accordingly, when one of the conditions exist to cause excessive
flood back to the compressor, the control means will sense that
condition and discontinue the operation of the ice maker even
though the level of accumulated ice within the bin is calling for
the production of ice.
In order to prevent the unit from trying to start when the freezing
chamber is full of ice or in an excessively cold ambient
atmosphere, the control apparatus has a safety thermostatic switch
preventing operation of the auger motor and the compressor motor
whenever the temperature of the evaporator adjacent an outlet end
of the freezing chamber is below a preselected value, for example
41.degree.F. In the event the auger motor becomes overloaded during
operation, a thermal overload switch will be actuated to interrupt
the operation of the auger motor.
The control apparatus also includes switch means connected with the
auger motor, the compressor motor and the thermal overload switch
and adapted to simultaneously operate the auger motor and the
compressor motor and to discontinue the operation of the compressor
motor in the event the overload switch stops the auger motor due to
an overloaded condition. Thus, the compressor, and a condensor fan,
which is controlled simultaneously with the compressor, are stopped
when the auger becomes overloaded during operation due to an
excessive accumulation of ice within the freezing chamber, thereby
to facilitate the thawing of the machine. The safety thermostatic
switch prevents restarting of the ice machine until the evaporator
temperature has risen above the preselected value to indicate that
the accumulated ice is thawed.
Occasionally it is necessary to clean the auger, the freezing
chamber and other components through which the inlet water and ice
pass, by circulating a cleaning solution, such as a citric acid,
solution through the machine. Manually operable switch means in the
control apparatus enable operation of the auger without
simultaneously operating the refrigeration circuit, thereby
enabling agitation of the cleaning solution during the cleaning
operation.
BRIEF DESCRIPTION OF THE DRAWING
The drawing is a schematic illustration showing an auger-type ice
maker for processing inlet water into a desired ice product
deposited in a bin, a refrigeration circuit for the ice maker and a
control apparatus embodying the principles of the present invention
for controlling the operation of the ice maker.
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT
Referring to the drawing, an auger-type ice maker, generally
indicated at 10, includes an evaporator unit 11 having a freezing
chamber formed with an internal bore having a cylindrical wall 12.
The evaporator unit 11 has an integrally formed evaporator
passageway 13 into which a refrigerant or coolant is expanded by a
refrigeration system, generally indicated at 14.
The refrigerant or coolant is expanded into the evaporator
passageway 13 through an expansion valve 16, and a compressor 17 is
in communication with the evaporator passageway via a suction line
18. The refrigeration system also comprises a condenser 19 serially
connected between the compressor 17 and the expansion valve 16. An
electric fan 21 circulates air through the condenser 19 to enhance
the efficiency of the operation of the refrigeration system.
Inlet water for the production of ice is introduced into the
evaporator unit 11 internally of the cylindrical wall 12 through an
inlet conduit 22 disposed near a base of the unit 11. The water
tends to freeze on the refrigerated wall 12 in the form of a thin
film of ice. One or more helical flights 23 formed or carried on a
rotating harvesting auger 24 cooperate with the cylindrical wall,
which, in effect forms a freezing and scraping surface, whereby
thin films of ice formed on that surface will be continuously
harvested. The auger 24 progressively advances a mixture of ice
particles, including slush and chunks, upwardly of the unit 11
towards a collection chamber 26 disposed superjacent of the
evaporator unit 11.
In order to produce a clear ice product, the inlet water may be
supplied in excess of an amount required for the production of ice.
In that manner, minerals and other impurities will migrate or be
frozen out of the thin film of ice and entrained in the liquid or
unfrozen portion of the inlet water. The excess amount of inlet
water, including the minerals and other impurities, is then
discarded or drained from the unit via the drain outlet 27 opening
above the collection chamber 26.
In order to compress the flake ice product harvested from the
refrigerated scraping surface into a solid ice product, a
compression auger 28 mounted for corotation with the harvesting
auger 24 receives the flake ice product from the collection chamber
26 and squeezes the ice particles through a nozzle bore 29 to
remove excess water and to form an emergent solid column of ice at
an upper end 31 of the nozzle bore. An appropriately configured
forming device may be secured at the upper end 31 of the nozzle
bore for forming the emerging, solid column of hard ice into a
desired configuration. As illustrated in the drawings, the forming
device includes an elbow 32 for urging the emerging column
transversely of the nozzle bore in a manner to break the column of
hard ice into cubes or sections. Other forms of ice products may be
produced by working the emerging column of hard ice, for example,
the column may be worked to form chipped ice, shaved ice, cracked
ice or small ice cubes.
The ice cubes formed as the emerging hard column of ice passes
through the elbow 32 are delivered to an appropriate storage bin 33
via a conduit 34 extending from an outer end 36 of the elbow to the
bin.
Suitable fastening means, such as bolts 37, secure the evaporator
unit 11 to a drive housing 38. A shaft 39 disposed centrally of the
evaporator unit 11 has a lower end portion supported within
appropriate bearing means in the drive housing 38 and drivingly
engaged by gear reduction means. Water is prevented from entering
the drive housing 38 by appropriate seal means including a shaft
seal 41 engaging the auger shaft 39.
In accordance with the principles of the present invention, the
operation of an auger drive motor 42, a compressor motor 43 and a
fan motor 44 is controlled by a control apparatus in a manner to
produce ice in reponse to a demand for ice in the storage bin 33
and in a manner to prevent damage to the ice maker 10 and its
various components.
The control apparatus includes control circuit means for
controlling the operation of the auger motor 42 so that the auger
motor is operated whenever the accumulation of ice within the bin
33 is below a preselected level and the temperature of the
compressor suction line 18 at a location adjacent to the compressor
17 is above a first preselected value and the operation of the
auger motor is discontinued whenever either the accumulation of ice
within the bin is above the preselected level or the temperature of
the compressor suction line is below a second preselected value
less than the first preselected value. Thus, the ice maker is
operated in response to the level of ice within the storage bin and
in response to the temperature of the suction line 18. In the event
there is an excessive flood back of the refrigerant or coolant to
the compressor 17, frost will accumulate on the compressor suction
line in the area adjacent the compressor. That excessive flood back
may be due to any number of reasons, including a lack of inlet
water being supplied to the freezing chamber via the inlet conduit
22, a "spin out" condition wherein the system is full of ice but no
new ice is being properly transferred from the freezing chamber or
an excessively low temperature operating condition.
As illustrated in the drawing, the control circuit means comprises
a series circuit including at least an input terminal 46 for
connection with an electric supply, the auger motor 42 and a
thermostatic control switch 47 having contacts positioned in
response to a sensed temperature by bellows means 48. The
thermostatic control switch 47 has a temperature sensing bulb
element 49 disposed within the bin 33 and positioned to sense the
temperature of the bin in a manner to indicate the level of ice
accumulated therewithin. A capillary tube 51 innerconnects the bulb
element 49 to the positioning bellows 48 and has a portion 51a
passing adjacent to or wrapped around the suction line 18 in an
area adjacent to the compressor 17. The thermostatic switch 47 is
of the type which operates in response to the coldest temperature
sensed, and thus, if either the suction line temperature falls
below the setting of the switch or the bin becomes sufficiently
full to lower the bin temperature below the setting of the switch,
the normally closed contacts of the switch will open to discontinue
operation of the auger motor, thereby stopping the production of
ice. By utilizing the capillary tube 51 to sense the condition of
the compressor suction line 18, the present invention provides a
low cost shut off device for the auger motor 42 and the compressor
43. In a commercial example of the ice maker 10, the contacts of
the control switch 47 are closed at sensed temperatures above
41.degree.F. and are opened when the sensed temperature drops below
35.degree.F.
In order to prevent the unit from trying to start when the
evaporator 11 is clogged with ice or when the unit is in an
excessively cold ambient atmosphere, the control apparatus of the
present invention inlcudes a safety thermostatic switch 52
preventing operation of the auger motor 42, and thus the compressor
motor, whenever the temperature of the evaporator adjacent an
outlet end of the freezing chamber is below a preselected value,
for example 41.degree.F. The safety thermostatic switch means is
connected in the control circuit in series between the control
thermostatic switch 48 and a thermal overload switch 53 for the
auger motor 42. The thermostatic safety switch 52 has contacts
positioned by an appropriate bellow means or the like as at 54,
with the bellow means being operated by a remote sensing bulb
element 56. The sensing bulb element 56 is partially wrapped around
an exterior of the evaporator unit 11 immediately subjacent the
collection chamber 26 or adjacent an outlet end of the freezing
chamber. Thus, a drop in the temperature of the evaporator unit 11
due to an excessive accumulation of ice within the freezing chamber
will be detected by the bulb element 56. In a commercial example of
the present invention, the contacts of the safety thermostatic
switch are closed at temperatures above approximately 41.degree.F.
and are opened below temperatures of about 35.degree.F., in a
manner similar to that of the controlled thermostatic switch
47.
It is also contemplated by the present invention to provide switch
means connected with the input terminal block 46, the auger motor
42, the auger motor thermal overload switch 53 and the compressor
motor 43 with the switch means being adapted to simultaneously
operate the auger motor and the compressor motor and to discontinue
the operation of the compressor motor whenever the operation of the
auger motor is discontinued due to the normally closed contacts of
the thermal overload switch opening or otherwise. That switch means
generally include a manually operable, double pole, double throw
switch 57 and relay switch means 58 having a relay coil 59
controlling the condition of a first set of normally opened
contacts 61 and a second set of normally opened contacts 62. The
manually operable switch 57 is the primary control switch for the
ice maker unit 10 and has a first set of contacts indicated at 63
and a second set of contacts indicated at 64, both of which are
normally closed when the switch 57 is positioned in the normal
running condition. The first set of normally closed contacts 63 are
connected in a series circuit comprising the control thermostatic
switch 47, the safety thermostatic switch 53, the thermal overload
switch 53 and the auger motor 42, thereby operating the auger motor
whenever the contacts of the control thermostat and the safety
thermostat are closed.
A lead 66 connected as at 67 between the thermal overload switch 53
and the auger motor 42 extends to the second set of normally closed
contacts 64 of the main control switch, and that set of contacts is
connected in series with the relay coil 59. Further, the series
circuit including the normally closed contacts 64 and the relay
coil 59 are connected in parallel with the auger motor 42. Thus,
when the main control switch 57 is in the running condition, as
illustrated in the drawings, the relay coil is energized, thereby
closing the two sets of contacts 61 and 62.
In order to avoid passing the start up current for the compressor
unit 43 through the main control switch 47, and thus enabling the
use of a switch having a lower rating, the second set of contacts
62 of the relay switch 58 are connected with the compressor motor
43 to control the operation of the same. Also, the fan motor 44 is
connected in parallel with the compressor motor 43 to operate in
unison therewith.
Since the relay coil 59 is disposed in parallel with the auger
motor 42, the relay coil will be deenergized whenever the operation
of the auguer motor is discontinued due to opening of the thermal
overload switch 53 or, the control switch 47.
The second set of normally closed contacts of the relay switch 58
are connected in parallel with the safety thermostatic switch 52,
thereby providing a circuit bypassing the safety thermostatic
switch once the unit has been started. That bypass circuit opens
whenever the auger motor 42 stops, thereby requiring the contacts
of the safety thermostatic switch to be closed before the auger
motor will restart. For example, when the auger motor 42 becomes
overloaded causing the thermal overload switch 53 to open, the
relay coil will be deenergized to open the first set of relay
contacts 61 so that the auger motor may not be restarted under a
loaded condition due to, for example, the evaporator unit 11 being
clogged with excessive ice.
During use, scale may accumulate on the walls of the freezing
chamber, the harvest auger 24 and the compression auger 28. The
accumulated scale may be cleaned by circulating an appropriate
cleaning solution, such as a citric acid solution, through the
machine. To enhance the cleaning operation, it is desirable to
agitate the cleaning solution, and thus, the control apparatus
includes switch means for a cleaning cycle wherein only the auger
motor 42 is operated without the compressor motor 43 and the fan
motor 44 being operated. Accordingly, the manually operable, main
control switch 57 includes a contact 68 which is normally opened
when the switch is positioned in the running condition and which
closes when the switch is positioned in a clean cycle condition.
The normally opened contacts 68 is connected in parallel with a
series circuit comprising the normally closed contacts 63 of the
switch 57, the control thermostatic switch 47 and the safety
thermostatic switch 52, thereby bypassing the safety thermostat and
the control thermostat to operate the auger motor 42. Since the
normally closed contacts 64 in series with the relay coil 59 are
opened during the clean cycle, the compressor motor 43 and the fan
motor 44 are not operated.
Although those versed in the art may suggest various minor
modifications, it should be understood that we wish to embody
within the scope of the patent warranted hereon, all such
modifications as reasonably and properly come within the scope of
our contribution to the art.
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