US3659430A

US3659430A - Defrost bimetal for interrupting time cycle ice maker during defrost-single timer

Info

Publication number: US3659430A
Application number: US47520A
Authority: US
Inventors: Duane C Nichols; William J Linstromberg
Original assignee: Whirlpool Corp
Current assignee: Whirlpool Corp
Priority date: 1970-06-18
Filing date: 1970-06-18
Publication date: 1972-05-02
Anticipated expiration: 1989-05-02
Also published as: CA919806A

Abstract

A refrigerator-freezer apparatus normally operating through freezing and defrosting portions of an operating cycle. The apparatus includes an ice maker and a timer motor that preferably also comprises the drive motor of the ice maker. A single temperature responsive switch in heat exchange relationship with the evaporator of the apparatus opens at an above freezing temperature condition of the evaporator so as to terminate operation of the defrost heater during the defrosting portion of the operation cycle and prevents cycling of the ice maker in the event of a high temperature condition, such as during start-up of the apparatus, to prevent the ice maker dumping unfrozen water into the freezer compartment of the apparatus.

Description

United States Patent Nichols et al.

451 May 2,1972

[54] DEFROST BIMETAL FOR INTERRUPTING TIME CYCLE ICE MAKER DURING DEFROST-SINGLE TIMER 721 inventors: Duane c. Nichols; William J. Llnstromberg, both of Evansville, Ind. 73 Assignee: Whirlpool Corporation [22] Filed: June 18, 1970 [21] Appl. No.: 47,520

52 us. ci. "62/233, 62/234 CAB! N ET THQRMOSTAT 3,208,233 9/1965 Linstromberg ..62/137 Primary Examiner--William E. Wayner Attorney-James S. Nettleton, Thomas E. Turcotte, Burton H. Baker, Gene A. Heth, Franklin C. Harter, Anthony Niewyk, Robert L. Judd and Hofgren, Wegner, Allen, Stellman and McCord [5 7] ABSTRACT A refrigerator-freezer apparatus normally operating through freezing and defrosting portions of an operating cycle. The apparatus includes an ice maker. and a timer motor that preferably also comprises the drive motor of the ice maker. A single temperature responsive switch in heat exchange relationship with the evaporator of the apparatus opens at an above freezing temperature condition of the evaporator so as to tenninate operation of the defrost heater during the defrosting portion of the operation cycle and prevents cycling of the ice maker in the event of a high temperature condition, such as during start-up of the apparatus, to prevent the ice maker dumping unfrozen water into the freezer compartment of the apparatus.

10 Claims, 2 Drawing Figures COMFRE 550R i 1 .av it l DEFROST swi'rcH t= It OEFROST HEATER DEFROST BIMETAL FOR INTERRUPTING TIME CYCLE ICE MAKER DURING DEFROST-SINGLE TIMER BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to refrigeration apparatus and in particular to refrigerator-freezer apparatus.

2. Description of the Prior Art 1 Ice makers and particularly domestic ice makers provide automatic means for forming ice bodies and dumping them into a receiver in the freezer compartment where they are maintained until used. Some of the ice makers now manufactured have means including thermostatically controlled motor means for harvesting the ice bodies as soon as a sufficiently low temperature has been achieved in the mold means of the maker to indicate that all liquid water has been frozen solid. Other types now manufactured use electrically operated timers to harvest the ice bodies on a schedule that is long enough between harvesting operations to ensure that all water in the ice body portion of the maker has been frozen. The invention described and claimed herein is concerned with such timer operated ice makers.

SUMMARY OF THE INVENTION One of the features of this invention is to provide a refrigerator apparatus operating through a cycle having freezing and defrosting portions and including an ice maker in heat exchange relationship with a freezer compartment for producing ice bodies, an electric control including a timer motor, a circuit for controlling a defrost means for periodically warming the evaporator to defrost temperature, a circuit including a high temperature delay switch means in heat exchange relationship with the evaporator for opening the defrost means circuit at an above freezing temperature of the evaporator, and switch means operated by the timer motor for energizing the timer motor and high temperature delay switch circuit during a normal ice making portion of the cycle and for energizing the defrost means circuit and timer motor during a defrosting portion of the cycle with the result that the timer motor is continuously energized during the entire normal operating cycle.

More specifically, the invention comprehends providing a refrigerator apparatus with a single electric motor for driving both the ice maker mechanism and the defrost heater mechanism. The timer motor provides a timed defrost cycle. However, in the event that the temperature reaches a preselected high temperature indicating a completion of the defrost operation prior to the end of the timed period, the high temperature delay switch discontinues further defrosting operation while permitting the timer motor to complete the timed cycle and restore the apparatus to normal operation upon completion of the timed period. The high temperature delay switch is connected to the timer motor to interrupt operation thereof other than during the timed defrost period in the event that the high temperature condition obtains, such as during start-up, i.e., when the refrigerator is first turned on after a condition of non-use wherein the evaporator is at an above freezing temperature.

BRIEF DESCRIPTION OF THE DRAWINGS Other features and advantages of the invention will be apparent from the following description taken in connection with the accompanying drawing wherein:

FIG. 1 is a side elevational view partially in vertical section illustrating a refrigerator apparatus embodying the invention; and

FIG. 2 is a schematic wiring diagram of the electrical circuitry of the apparatus of FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT In the exemplary embodiment of the invention as disclosed in the drawing, a refrigerator-freezer includes an insulated cabinet 11 having an upper freezer compartment 12 and a lower refrigerator compartment 13 each having a front access opening normally closed by its

own door

14 and 15, respectively.

Separating the upper freezer compartment 12 from the lower refrigerator compartment 13 is an inclined generally horizontal insulated wall 16. Overlying wall 16 is a conventional refrigerant evaporator 17 composed of a serpentine tube 18 and spaced vertically arranged fins 19 interconnecting the tubes and in heat exchange relationship therewith.

Located at the back of the freezer compartment 12 is a motor operated air circulating fan 20 in an air conduit housing 21. This fan 20 is positioned to draw air directly from the rear of evaporator 17 and circulate it through the upper freezer compartment 12 as indicated by the arrows 22 and through the refrigerator compartment 13 as indicated by the arrows 23. As indicated in FIG. 1, the two streams of

air

22 and 23 are returned to the evaporator 17 at the front thereof for passage rearwardly therethrough and back into the fan 20.

Located in freezer compartment 12 so as to be in heat exchange relationship with the subfreezing temperature therein is an automatic ice maker 24 of conventional construction having a motor operated control mechanism 25 and an ice body forming portion 26 operated thereby.

The refrigerator apparatus of this invention as illustrated in the drawings comprises a refrigeration system including a compressor 27 and evaporator 17 which are parts of a usual refrigeration system that also employs a refrigerant condenser as well as other conventional refrigeration system portions (not shown).

The electrical circuit of the illustrated apparatus is shown in FIG. 2 to include a first electrical circuit having an electric lead 28 connecting in series a cabinet thermostat switch 29 and compressor 27. The other side of compressor 27 is connected to one power supply lead 31. Cabinet thermostat switch 29 which thereby controls the operation of compressor 27 is positioned in heat exchange relationship with the interior of refrigerator compartment 13.

The wiring of the apparatus also includes a second circuit comprising a lead 33 connected to a timer motor 34 whose other side is connected by a lead 35 to lead 31.

The wiring of the apparatus also includes a third circuit comprising an electric lead 36 that connects to a defrost heater 37 whose other side is connected by a lead 38 also to lead 31.

A fourth circuit is also provided comprising a defrost bimetal thermostat switch 40 connected to the other power supply lead 39. As shown in FIG. 1, thermostat switch 40 is mounted on a heat conducting part of evaporator 14 to be in heat exchange relationship therewith.

The wiring also includes switch means 41 operated by timer motor 34 and embodied in a pair of switches, one of which has a first fixed contact 41b in the first circuit that includes

leads

28 and 31, thermostat switch 29 and compressor 27, and a second fixed contact 410 in the second circuit that includes lead 33 and timer motor 34. In addition, the one switch 41 includes a moving contact 41a. Moving contact 4111 is connected to power supply lead 39.

The switch means operated by the timer motor 34 also includes another switch 45 similar to the one switch 41 and including a first fixed contact 45b in the second circuit which includes lead 33 and the timer motor 34 and a second fixed contact 45c in the third circuit that includes

leads

36 and 38 and defrost heater 37 that is in series therewith. Switch 45 also includes a moving contact 45a connected in the fourth circuit in series with defrost bimetal thermostat switch 40.

As illustrated in FIG. 2, during the normal freezing portion of the cycle, moving contacts 410 and 45a are in the position shown so as to energize the compressor 27 to maintain a subfreezing temperature in freezer compartment 12 and thus forrn ice bodies in the ice maker and also energize timer motor 34 by way of defrost bimetal switch 40 and moving contact 45a. In this normal freezing operation, the defrost heater 37 is, of course, de-energized.

To initiate a defrosting operation, timer motor 34 which is operatively connected to both switches 41 and 45 (as indicated by broken line 49) throws the respective moving contacts 41a and 450 from engagement with the respective fixed contacts 41b and 45b into engagement with the other fixed contacts 41c and 45c. This de-energizes compressor 27 to terminate the freezing portion of the cycle and energizes the defrost heater 37 to initiate the defrosting portion of the cycle. Defrosting is continued until timer motor 34 again throws the moving contacts 41a and 45a to the positions shown in FIG. 2. If before this time evaporator 17 has been completely defrosted, the high temperature thereof will be sensed by defrost thermostat switch 40 which will be open to de-energize defrost heater 37.

Defrost bimetal thermostat switch 40 not only functions as indicated above to terminate the energization of heater 37 when the evaporator has been defrosted during the defrosting portion of the cycle, but also serves as a delay switch during the freezing portion of the cycle. Thus, the timing cycle for initiation of ice body harvesting will be delayed until temperature conditions are satisfactory for forming ice at a predetermined minimum rate. The dumping of liquid water or partially frozen ice bodies into the freezer compartment will thus be prevented. Thus, in the present invention, a single bimetal thermostat switch 40 which is customarily provided in the refrigerator circuit is used both as a delay switch to prevent accidental dumping of water by timer motor 34 and also to terminate heating of defrost heater 37 when defrosting is complete during the defrosting portion of the cycle. The principal danger times during which unfrozen water may be dumped by the ice maker are those when the refrigerator is first turned on, and when the refrigerator is in its defrost portion of the cycle.

If during the defrost portion of the cycle as previously described, bimetal thermostat switch 40 opens, timer motor 34 will continue to operate as it is energized byway of moving contact 410, lead 33 and lead 35 between the two power supply leads. The timer motor will remain energized until it has completed the throwing of

switches

41 and 45 back to the positions shown in FIG. 2 whereupon the compressor is operated to reduce the temperature in the refrigerator. When defrost thermostat switch 40 is cooled to a predetermined subfreezing temperature, it will close and the timer motor will be energized to start the freezing portion of the cycle.

Thus, the invention .comprehends a refrigerator apparatus having means 24 for forming ice bodies including refrigeration means comprising an evaporator 17 and a compressor 27 for providing a freezing condition therein, means 37 for defrosting the apparatus periodically, an electric timer motor 34 providing a timed operation of the means for forming ice bodies and the defrosting means, and control means for preventing operation of the timer motor 34 as a result of an above freezing temperature condition of the refrigeration means while concurrently permitting operation of the refrigeration means, the control means being arranged to cause operation of the timer motor upon elimination of the above freezing temperature condition.

Having described my invention as related to the embodiment shown in the accompanying drawings, it is my intention that the invention be not limited by any of the details of description, unless otherwise specified, but rather be con- 1 strued broadly within its spirit and scope as set out in the appended claims.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. Refrigerator apparatus comprising: means for forming ice bodies including refrigeration means for providing a freezing condition therein; means for defrosting the apparatus periodically; an electric timer motor driving said means for forming ice bodies through a preselected cycle and providing a timed operation of said defrosting means; and control means connected with said forming means, defrosting means, and motor for preventing operation of the timer motor as a result of an above freezing temperature condition of said refrigeration means while concurrently permitting operation of said refrigeration means, said control means being arranged to cause operation of said timer motor upon elimination of said above freezing temperature condition.

2. The refrigerator apparatus of claim 1 wherein said refrigerator means includes a motor driven compressor and said control means includes a switch connected to permit operation of the compressor only other than during a defrosting operation.

3. The refrigerator apparatus of claim 1 wherein said refrigeration means comprises a motor driven compressor and said control means includesa switch connected to permit operation of the compressor only other than during the timed operation of said defrosting means.

4. The refrigerator apparatus of claim 1 wherein said control means comprises means for preventing operation of the timer motor during start-up of the apparatus from a condition of non-use wherein the refrigeration means is at an above freezing temperature.

5. A refrigerator apparatus operating through an operating cycle having freezing and defrosting portions, comprising: means forming a freezer compartment; a refrigeration system including a compressor and an evaporator for chilling said compartment to a subfreezing temperature; an ice maker in heat exchange relationship with said compartment for producing ice bodies; a first circuit including a first thermal switch means for periodically operating said compressor to maintain said subfreezing temperature; a second circuit including a timer motor; a third circuit including a defrost means for periodically warming said evaporator to defrosting temperature; a fourth circuit including a high temperature limiting second switch means in heat exchange relationship with said evaporator for opening said fourth circuit at an above freezing temperature of said evaporator; and switch means operated by said timer motor for energizing said first, second and fourth circuits during the freezing portion of the operating cycle and for energizing the second, third and fourth circuits during the defrosting portion of the operating cycle, said timer motor being de-energized by an open condition of said fourth circuit in said freezing portion of the operating cycle.

6. The apparatus of claim 5 wherein said switch means comprises one switch having a first contact in said first circuit, a second contact in said second circuit and a current carrying arm movable therebetween, and another switch having a first contact in said second circuit, a second contact in said third circuit and a current carrying arm movable therebetween.

7. The apparatus of claim 6 wherein said apparatus includes means operated by said timer motor for moving both said switch anns simultaneously into engagement with said first contacts and then into engagement with said second contacts.

8. The apparatus of claim 6 wherein saidfourth circuit that includes said temperature limiting second switch means also interconnects both said switch arms.

9. The apparatus of claim 6 wherein said apparatus includes means operated by said timer motor for moving both said switch arms simultaneously into engagement with said first contacts and then into engagement with said second contacts, and wherein said fourth circuit that includes said temperature limiting second switch means also interconnects both said switch arms.

10. The apparatus of claim 9 wherein said ice maker includes an electric motor drive means, the motor of which comprises said timer motor.

* t i l

Claims

3. The refrigerator apparatus of claim 1 wherein said refrigeration means comprises a motor driven compressor and said control means includes a switch connected to permit operation of the compressor only other than during the timed operation of said defrosting means.

7. The apparatus of claim 6 wherein said apparatus includes means operated by said timer motor for moving both said switch arms simultaneously into engagement with said first contacts and then into engagement with said second contacts.

8. The apparatus of claim 6 wherein said fourth circuit that includes said temperature limiting second switch means also interconnects both said switch arms.