US3739595A

US3739595A - Flexible mold ice maker control

Info

Publication number: US3739595A
Application number: US00183433A
Authority: US
Inventors: L Learn; W Moreland
Original assignee: Westinghouse Electric Corp
Current assignee: CBS Corp
Priority date: 1971-09-24
Filing date: 1971-09-24
Publication date: 1973-06-19
Anticipated expiration: 1990-06-19

Abstract

Energization of a thermostat reset heater for a flexible mold ice maker is controlled in accordance with the application of vacuum and pressure to the flexible mold so that premature termination of harvesting and fill operation is avoided. Energization of the reset heater is also controlled in accordance with the level of ice cubes in the receiving bin, and in accordance with the bin position.

Description

United States Patent 1 Learn et al.

FLEXIBLE MOLD ICE MAKER CONTROL June 19, 1973 Primary Examiner-William E. Wayner Assistant Examiner-William E. Tapolcai, Jr. Attorney- F. H. Henson and E. C. Arenz [73] Assignee: Westinghouse Electric Corporation,

Pittsburgh, Pa.

[22] Filed: Sept. 24, 1971 [57] ABSTRACT [21] Appl- 183,433 Energization of a thermostat reset heater for a flexible v mold ice maker is controlled in accordance with the ap 52 vs. C]. 62/135, 62/353 plication of vacuum and P to the flexible mold 51 Int. Cl. F25c 1/06 so that Premature termination of harvesting and fill P' 53 Field f Search 62/137, 135 353; eration is avoided. Energization of the reset heater is 137/624 l8 also controlled in accordance with the level of ice cubes in the receiving bin, and in accordance with the [56] References Cited bin Position- T ED STATES PATENTS 7 Claims, 7 Drawing Figures 3,388,560 6/l968 Moreland 62/353 so 2Q w x "J "J I W U 51.. Pin up 64 4 t 20 44 7 -Zmo $262 a 60 3 74- 5s 50 54 5B 66;

PAIENIED JUN I 9 I075 SREEIZNG PATENIEU JUN 9 973 sum 3 or 4 1111111111 IIIIIIIIIIIIIIIIII I 1111111111! PAIENTED sum b N 4 ELECTRIC AIR PUMP JIIIIIIIIIIIIIIIIIIIIIIJ[IL/1 I I I I I f I I I I I I I I I I I I f I f f I J If? FLEXIBLE MOLD ICE MAKER CONTROL CROSS-REFERENCE TO RELATED APPLICATION U.S. Pat. application Ser. No. 874,598 filed Nov. 6, 1969, now U.S. Pat. No. 3,648,732 discloses a pneumatic ice maker and self-advancing programmer of a currently preferred character with which this invention may be employed.

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention pertains to the art of controlling flexible mold ice makers in which the mold is inverted to eject the cubes and then is restored to a position to receive water for a subsequent batch of cubes.

2. Description of the Prior Art The use of a reset heater with a thermostat to control starting and stopping the operation during which ice is harvested and the cube cavities are filled with water in automatic ice makers of various types'is well known. Examples of reset heaters used with thermostats in automatic ice makers of the hydraulic type are disclosed in U.S. Pat. Nos. 2,770,102 and 3,388,560.

The manner in which the thermostat and reset heater function willbe explained in general terms to aid in understanding the distinctive character of the present invention. The thermostat performs the function of starting and stopping the harvesting and fill operation (hereinafter called operation).'The thermostat is located in a position to be responsive to temperature changes of the contents of the cube cavities. As water in the cube cavities cools down and freezes, the thermostat will correspondingly cool down. When the thermostat reaches its trip temperature of, say, to F below the freezing temperature, the thermostat causes its associated switch to close. This starts the harvesting part of the operation, which automatically takes place, and is followed by the fill part of the operation during which water is introduced to the cube cavities of the tray. Under normal conditions, the water is sufficiently warm to reset the thermostatic switch to an open position after a short period of time, thereby stopping the operation. However, to assure reset under a condition when extremely cold water is admitted to refill the tray, a heater has typically been added which is in heat exchange relation with the thermostat. If this heater is controlled only by the thermostat (i.e., it is energized when the thennostatic switch closes and deenergized when the thermostatic switch opens) the wattage of the heater and thermal impedance between the heater and thermostat become rather critical. Too high a wattage can reset the thermostat before the operation is complete, and too low a wattage is insufficient to reset the thermostat if the tray has been soaking for an appreciable time in an exceptionally low temperature freezer. Line voltage variations may also affect the operation because they contribute large power changes to the heater.

It is to the solution of the above-noted problems of obtaining proper reset of the thermostat in a flexible mold ice maker that the invention is in part directed.

SUMMARY OF THE INVENTION In accordance with one aspect of the invention, a switch for controlling the reset heater is operated to a position energizing the reset heater only when the flexible mold is subjected toa vacuum condition. In my currently preferred type of flexible mold automatic ice maker, in which a vacuum is applied to condition the mold to receive water for each subsequent batch of cubes, the major part of the on time of the reset heater occurs at the end of an operation, so that reset of the thermostat is assured without any appreciable likelihood of a premature reset of the thermostat. With this timing sequence, the wattage for the reset heater may be chosen to be high enough to reset the thermostat under the worst conditions anticipated.

The invention contemplates providing means responsive to the volume of ice cubes stored in the cube re ceiving bin and being operatively connected to the reset heater switch means to maintain the switch means in a position energizing the reset heater in response to a build-up of ice volume beyond a predetermined level. The arrangement also lends itself to incorporating means responsive to the removal of the bin from a normal ice receiving position to operate the switch means to the position in which the reset heater is maintained energized.

DRAWING DESCRIPTION FIG. 1 is a vertical sectional view of an arrangement for carrying out the invention and. illustrating the position of the parts during the period between successive operations;

FIG. 2 is a vertical sectional view of a fragmentary portion of the parts of FIG. 1 and showing the parts in the positions they assume when the flexible mold is subject to a vacuum condition and in which further production of cubes is indicated;

FIG. 3 is a view similar to FIG. 2, but showing the position of the parts when an adequate quantity of cubes is available and further production is to be halted;

FIG. 4 is a view similar to FIG. 31, but showing the position of the parts while a batch of cubes freezes and with further harvesting being precluded until some of the cubes have been removed from the bin;

FIG. 5 is a view similar to FIG. 4 but showing the position of the parts while the bin is removed from its proper cube receiving position;

FIG. 6 is a schematic view of the circuit arrangement and basic connections between a programmer, pump, and the tray; and

FIG. 7 is a vertical sectional view of an arrangement which provides automatic shut-off of ice making when the bucket is full of cubes and in which the weight of ice cubes provides the signal for shut off.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention can be carried out in connection with any automatic ice maker having a flexible mold and to which a vacuum is applied after cube ejection to place the mold in condition to receive water for a subsequent batch of cubes. However, the inventionwill be de scribed in connection with an arrangement as disclosed in U.S. Pat. application Ser. No. 874,598, which is the currently preferred system as presently contemplated, and to which reference should be had for a full description of a harvesting and fill operation. For present purposes, it will suffice to note that the pneumatic programmer 10 of FIG. 6 is powered by an electric air pump 12 connected thereto by the suction and

pressure lines

14 and 16. The line 18 represents the line which provides either suction or pressure to the tray 20 while the line 22 represents the line which furnishes water to the tray.

Referring to FIG. 1, the tray and its associated parts, along with the underlying ice receiving bin 24, are all located in a freezer compartment 26 having a rear wall 28 to which the rigid tray 20 is fixedly secured.

The space 30 between the rigid tray 20 and the flexible bladder or mold 32 is in communication with the line 18 connected to the pneumatic programmer 10. The mold is formed so that with neither pressure nor vacuum in the space 30 it assumes the form shown in FIG. 1 in which individual cube cavities are presented. When a vacuum is applied to the space 30, the mold assumes the form shown in FIGS. 2 and 3. When the space 30 has adequate pressure applied thereto, the mold is inflated (not shown) to invert the cube cavities and eject the ice cubes into the bin. The thermostat assembly 34 (FIGS. 1 and 6) is secured to the tray 20 and is located in the space 30 in a position of good heat exchange relation with the bottom of one of the cube cavities. The thermostat assembly includes the thermostatically controlled switch 36 as well as a reset heater 38 in good heat exchange relation with the temperature responsive part of the thermostat. The switch 40 which controls the reset heater is of the leaf type and is shown in end view in FIG. 1. The opposite end of the switch 40 is supported by structure attached to the rigid tray 20.

Two

actuator diaphragm assemblies

42 and 44 are shown in FIG. 1. Since the parts of each are for the most part the same, the parts of only one will be described in some detail. The chamber 46 ofeach is in communication with the space 30 between the tray and mold, and is sealed by a flexible diaphragm 48 which has a stem 50 secured thereto for movement therewith and which is biased downwardly by a compression spring 52 to the normal at-rest position as shown in I FIG. 1. One end of an actuating arm 54 is secured to the bottom end of the stem of the right assembly 44 while an intermediate part of the arm is secured to the bottom of the stem of the left assembly 42. The free end 56 of the actuator arm is located to be moved upwardly into a position engaging the reset heater switch in accordance with the pressure of suction conditions controlling the diaphragm assemblies.

A cube level sensing arm 58 is also associated with the right diaphragm assembly 44. At point 60 the sensing arm is pivotally secured to structure connected to the rigid tray to provide a fixed pivotal location for the arm. At point 62 the one end of the sensing arm is pivotally secured to the stem of the right diaphragm assembly 44 to provide a movable pivot location.

A latch 64 for the reset heater switch 40 is fixed to the underside of the tray 20. It is positioned so that the lower hook shaped end of the latch will hold the switch 40 closed when the free end 56 of the actuating arm lifts the lower leaf of the switch 40 sufficiently high as shown in FIG. 3. This occurs under a condition of an adequate height of cubes being sensed by the sensing arm 58.

The arrangement according to the invention also includes a reset arm 66 which functions in accordance with the bin 24 position and can operate against both the latch 64 and the reset heater switch 40 as will be explained in connection with FIGS. 4 and 5. The reset arm is pivotally fixed at point 68, has a lower end portion adapted to be engaged by the upper rear edge of the bin 24 when the bin is in a proper ice receiving position, and has an upper end which includes the latchengaging-face 70 and an off-set switch-engaging-face 72. A compression spring 74 biases the reset arm 66 in a counterclockwise direction.

OPERATION (FIGS. 1-6) The cold air in the freezer cools the water previously discharged into the cube cavities of the flexible mold 32, and ice cubes are formed. The thermostat 34, being heat stationed close to the bottom of one of the cube cavities, senses the cube temperature and is designed to close its switch 36 on a drop in temperature to a point of, say, between 12 to 20F. A temperature in this range is considered to provide sufficient sub-cooling below the freezing point of water to make sure that the cubes in all the othercavities are also frozen.

Closure of the contacts of the thermostatically controlled switch 36 completes the circuit through lines 76 and 78 (FIG. 6) to energize the air pump 12 and thereby initiate the harvesting and till operation. The programming valve 10 controls the system from this point to the end of the operation in a fashion described in detail in the earlier noted patent application. In accordance therewith, a suction is first drawn in the space 30 for a relatively short period of time, typically 15 to 20 seconds, to provide a prestripping action as the mold is drawn down against the tray by the suction and peeled away from the cubes. The form of the mold in this condition is illustrated in FIG. 2. The

actuator diaphragm assemblies

42 and 44 are also displaced upwardly by atmospheric pressure as shown in FIG. 2 and accordingly pull the sensing arm about its pivot 60 to the position shown in FIG. 2, assuming that the level of cubes is as shown in FIG. 2 so that the cubes do not obstruct full movement of the arm. The actuating arm 54 is pulled upwardlyito the location as shown in FIG. 2 to close the reset heater switch 40 to thereby energize the reset heater 38 through completion of a circuit including the heater and switch as shown in FIG. 6. The wattage of the reset heater 38 is selected so that it it takes a substantially longer time of heating to reset the thermostat from its trip temperature to its reset temperature than the time taken for prestripping. For example, in the general arrangement shown, a heater wattage of 1.5 watts requires approximately 2 minutes to reset the thermostat. Since the prestripping operation normally taken less than half a minute, the programming valve will move to the next position long before the reset of the thermostat and the operation will continue by converting the vacuum condition to a pressure condition in the space 30.

With an adequate pressure, the mold is inflated to invert the cube cavities and thus eject the cubes. Upon the change from vacuum to pressure, the actuator diaphragm assemblies return by the force of the compression springs 52 to the positions shown in FIG. 1. As such, the reset heater switch contacts 40 have opened and the reset heater is no longer energized. As the operation proceeds beyond cube ejection, the program mer valve 10 advances further to a position in which the flexible mold is deflated.

At the end of the deflation, a vacuum is again applied to the tray space 30 to assure a complete return of the mold to a FIG. 2 position. The vacuum operated water valve associated with the programmer is operated at this time so that water fills the batch chamber associated with the programmer valve in approximately 5 to seconds. During thisshort period, the actuator diaphragm assemblies, actuator arm and sensing arm will have again assumed the position shown in FIG. 2 with the reset heater switch 40 closed (again assuming as before that no cubes interfere with the movement of the I sensing arm 58). The programmer valve continues its advance and releases the vacuum in the tray space 30 so that the parts return to the FIG. 1 position.

Water is then forced from the batch valve up to the cube cavities through the water line 22 and discharge tube 80. The programmer then advances to its final position in which the water remaining in the line 22 returns to the batch valve and a vacuum is again applied to the tray space 30. The parts again take a FIG. 2 position. After a short period, the water in the cavity in conjunction withthe energized reset heater 38 will cause the thermostat 34 to reset by opening the thermostatic switch contacts 36. This turns off the air pump 12. The pressures in the system then equalize and the actuator diaphragm assemblies and associated parts return to the position shown in FIG. 1. When the water subsequently freezes, the thermostatically-controlled switch 36 will again close and another harvesting and fill operation will start.

It will be appreciated from the foregoing that so long as the cube receiving bin 24 is not removed, and so long as the level of cubes therein does not reach a level in which the downward pivoting of the sensing arm 58 is restricted, the operation of the parts will be as in FIGS. 1 and 2 only.

After the cube level builds up to a position in the bin such as shown in FIG. 3, when the sensing arm 58 swings down its movement is blocked by the cubes and is accordingly prevented from completing its normal swing. This in turn prevents the right actuator diaphragm assembly 44 from completing its normal upward displacement. Since the left actuator diaphragm assembly is not so inhibited, the actuating arm 54 tilts as shown in FIG. 3 so that the free end 56 of the arm forces the switch leafs 40 sufficiently above their normal closed position that the hook of the latch 64 snaps over under the lower leaf to hold the switch closed irrespective of the position of the actuator arm 54. As the programming valve continues its advance the actuator diaphragm assemblies return to their initial positions as in FIG. 4 but the switch 40 contacts are held closed by the latch 64. In this way, power is supplied continuously to the reset heater and the thermostat is prevented from starting another harvesting and fill operation even though a fill occurs and a new batch of cubes are frozen. Thus, the system is maintained in the off condition by preventing the thermostat from being cooled down to its trip temperature.

The manner in which the system is restored to normal operation by removal of the ice bin 24 and removal of ice cubes therefrom will be described principally in connection with FIG. 5. When the user moves the bin 24 forwardly, the compression spring 74 causes the reset arm 66 to pivot counterclockwise to the position shown in FIG. 5. As such, the latch engaging face 70 of the arm moves the latch 64 from its position holding the switch 40 closed. However, the switch engaging face -72 of the reset arm engages the switch 40 to hold it closed. Thus, if the bin is either removed from the freezer, or is not fully returned to its proper position,

the ice maker will be prevented from starting a harvesting operation because of the closed switch 40. When the bin 24 is pushed back into its proper position, it engages the lower end of the reset arm 66 and pivots it back to the position shown in FIG. 1 so that the switch will open and deenergize the reset heater. Subse quent cooling of the thermostat to its trip point can then initiate another operation.

The use of the vacuum condition to control the switch for the reset heater may be employed whether prestripping is provided or not. The prestripping operation being relatively short does not adversely affect the operation of the system. However, it is conceivable that with improved mold materials a prestripping operation may not be required, in which case the reset heater is first energized only when the mold is drawn back into a water receiving condition.

ALTERNATIVE ARRANGEMENT The arrangement in FIG. 7 illustrates how automatic shut off may be obtained in another fashion when the fin is full of cubes. In this case a single actuator diaphragm assembly 82 is used and the reset heater switch 40 is incorporated in the tray space 30. The actuator diaphragm assembly is essentially the same as those of FIGS. 1-5. A lever 84 is pivoted on a bearing 86 mounted on the support 88 which is in turn attached to the back wall of the freezer compartment. A forked forward end of the lever 84 is held captive by the lower end of the actuator stem. Thus, .as the diaphragm moves up and down during the operation in accordance with vacuum and pressure conditions in the space 30, the lever 84 is forced to move also. The back end of the bin 90 has a ledge 92 supported by the rear end of the lever 84. The ice bin 90 is arranged with a front foot 94 which rests upon a shelf in the freezer compartment. The bin pivots around this front foot in accordance with the weight of the ice cubes in the bin. Thus, the

weight of the ice cubes will work in opposition to the force of the compression spring 52 in the actuator diaphragm assembly. The operation of the arrangement of FIG. 7 will be in general terms the same as the operation of the arrangement of FIGS. 1-5 so far as the application of pressure and vacuum to the tray space 30 result in the actuator diaphragm assembly responding and controlling the operation of the reset heater switch 40. However, if the weight of the ice cubes in the bucket reaches a predetermined amount, the lever 84 will be pivoted and held in a counterclockwise pivoted position such that the switch 40 remains closed even though no vacuum exists in the space 30. In the same fashion as described heretofore, this prevents the thermostatfrom closing for a subsequent operation until sufficient ice cubes have been removed to reduce the weight thereof to an amount that further harvesting of ice cubes is indicated.

The schematic, of FIG. 6 is applicable to both arrangements described herein.

A manual on-off switch may be placed in the circuit to prevent operation of the air pump, or a switch may be placed in parallel with the reset heater switch 40 to provide manual on-off control in that fashion.

What we claim is:

1. In a flexible mold ice maker of the type having a harvesting and fill operation in which pressure is applied to invert the mold and eject the cubes into a bin, and a vacuum is then applied to condition the mold to receive water for a subsequent batch of cubes, a control arrangement including:

a thermostat subject to the heat of the contents of the mold and operable to initiate said harvesting and fill operation in response to a temperature depression corresponding to the contents being adequately frozen, and to terminate the cycle in response to a temperature rise corresponding to the receipt of water of normal temperature into the mold;

heater means in heat exchange relation with said thermostat to insure sensing a temperature rise by said thermostat;

switch means for controlling energization of said heater means; and

means in communication with the space to which said pressure and said vacuum applied and movable in accordance with the application of said pressure and said vacuum for effecting operation of said switch means to a position energizing said heater means in response to the application of said vacuum.

2. In an ice maker according to claim 1:

means responsive to the level of cubes in said bin an arranged to maintaining said switch means in a position energizing said heater means in response to a build-up cubes beyond a predetermined level.

3. In an ice maker according to claim 1:

means responsive to removal of said bin from a normal cube receiving position for placing said switch means in a heater means energizing position.

4. In an ice maker according to claim 1 wherein:

said switch operating means comprises a pair of movable diaphragm assemblies carrying means for engaging said switch means; and

cube level sensing means responsive to the level of cubes in said bin and being connected to one of said diaphragm assemblies to restrict the movement of said one diaphragm assembly when the cubes-exceed a predetermined level.

5. In an ice maker according to claim 1 including:

a pair of diaphragm assemblies carrying a switch actuating arm and being movable for substantially the same distance under normal conditions in response to said vacuum condition; cube level sensing means connected to one of said diaphragm assemblies to restrict the movement of said one diaphragm assembly in response to a cube level above a predetermined level so that a switch engaging end of said actuator arm moves said switch beyond its normally closed position; and

latch means for holding said switch beyond said normally closed position upon the return of said diaphragm assemblies to their normal position in the absence of said vacuum condition.

6. In an ice maker according to claim 5 including:

reset arm means movable in accordance with positioning of said bin and operable to disengage said latch means from said switch means upon the removal of said bin and to maintain said switch means closed, until said bin is subsequently replaced in its normal ice receiving position.

7. In a pneumatic ice maker in which a harvesting and fill operation takes place in accordance with energization of means subjecting a space closed by a flexible cube mold to vacuum and pressure conditions," a control arrangement including:

thermostatic means responsive to a temperature corresponding to a well-frozen condition of said ice to energize said means for subjecting said space successively to a vacuum, pressure, and vacuum condition, and responsive to a temperature above freezing corresponding to a supply of water of normal temperature to said mold to deenergize said means; 7

reset heater means energizable to apply heat to said thermostat;

switch means for controlling energization of said reset heater means; and

means for operating said switch means to a position energizing said heater means only when said vacuum condition exists.

Claims

1. In a flexible mold ice maker of the type having a harvesting and fill operation in which pressure is applied to invert the mold and eject the cubes into a bin, and a vacuum is then applied to condition the mold to receive water for a subsequent batch of cubes, a control arrangement including: a thermostat subject to the heat of the contents of the mold and operable to initiate said harvesting and fill operation in response to a temperature depression corresponding to the contents being adequately frozen, and to terminate the cycle in response to a temperature rise corresponding to the receipt of water of normal temperature into the mold; heater means in heat exchange relation with said thermostat to insure sensing a temperature rise by said thermostat; switch means for controlling energization of said heater means; and means in communication with the space to which said pressure and said vacuum applied and movable in accordance with the application of said pressure and said vacuum for effecting operation of said switch means to a position energizing said heater means in response to the application of said vacuum.

2. In an ice maker according to claim 1: means responsive to the level of cubes in said bin and arranged to maintaining said switch means in a position energizing said heater means in response to a build-up cubes beyond a predetermined level.

3. In an ice maker according to claim 1: means responsive to removal of said bin from a normal cube receiving position for placing said switch means in a heater means energizing position.

4. In an ice maker according to claim 1 wherein: said switch operating means comprises a pair of movable diaphragm assemblies carrying means for engaging said switch means; and cube level sensing means responsive to the level of cubes in said bin and being connected to one of said diaphragm assemblies to restrict the movement of said one diaphragm assembly when the cubes exceed a predetermined level.

5. In an ice maker according to claim 1 including: a pair of diaphragm assemblies carrying a switch actuating arm and being movable for substantially the same distance under normal conditions in response to said vacuum condition; cube level sensing means connected to one of said diaphragm assemblies to restrict the movement of said one diaphragm assembly in response to a cube level above a predetermined level so that a switch engaging end of said actuator arm moves said switch beyond its normally closed position; and latch means for holding said switch beyond said normally closed position upon the return of said diaphragm assemblies to their normal position in the absence of said vacuum condition.

6. In an ice maker according to claim 5 including: reset arm means movable in accordance with positioning of said bin and operable to disengage said latch means from said switch means upon the removal of said bin and to maintain said switch means closed, until said bin is subsequently replaced in its normal ice receiving position.

7. In a pneumatic ice maker in which a harvesting and fill operation takes place in accordance with energization of means subjecting a space closed by a flexible cube mold to vacuum and pressure conditions, a control arrangement including: thermostatic means responsive to a temperature corresponding to a well-frozen condition of said ice to energize said means for subjecting said space successively to a vacuum, pressure, and vacuum condition, and responsive to a temperature above freezing corresponding to a supply of water of normal temperature to said mold to deenergize said means; reset heater means energizable to apply heat to said thermostat; switch means for controlling energization of said reset heater means; and means for operating said switch means to a position energizing said heater means only when said vacuum condition exists.