US3896278A - Freezer monitor thermal responsive switch with gravity actuated plunger contact retained by freezable liquid in open switch position - Google Patents

Abstract

A freezer monitor switch comprising an elongate, hollow tube which is closed at one end and has its other end equipped with a closure. A pair of current carrying leads communicate with the interior of the tube through the closure and terminate interiorly in a pair of spaced contacts. A small quantity of water or other freezable liquid and a slidable, electrically conductive element are retained interiorly of the tube. The switch initially mounts within the freezer with the open end facing upwardly and with the closed end positioned downwardly until such time as the water freezes and secures the conductive element at the closed end of the tube. The switch is then rotated through 180* within the freezer and is positioned with the frozen in place conductive elements above the contacts. Should the freezer fail for any reason, the water will melt to thereby release the conductive element which falls by gravity and bridges the space between the conductive contacts. Preferably, the electrical leads and contacts form parts of an alarm circuit which will be energized upon contact of the conductive element with the pair of spaced contacts.

Description

United States Patent [191 Muraw ski et al.

1 July 22, 1975 [54] FREEZER MONITOR THERMAL RESPONSIVE SWITCH WITH GRAVITY ACTUATED PLUNGER CONTACT RETAINED BY FREEZABLE LIQUID IN OPEN SWITCH POSITION [76] Inventors: Stephen Murawski; Bernard J.

McKairnes, both of 1846 E. Schiller St., Philadelphia, Pa. 19134 22 Filed: Jan. 8, 1974 21 Appl.No.: 431,747

[52] US. Cl 200/52 R; ZOO/61.58 R; ZOO/61.83;

[51] Int. Cl. H0lh 37/74 [58] Field of Search 200/52 R, 61.58 R, 85 R, ZOO/61.83, DIG. 18', 337/408, 298, 312, 314, 315, 401, 402; 62/125-131, 161, 164,

[56] References Cited UNITED STATES PATENTS 1,095,382 5/1914 Clorius 337/408 2,007,409 7/1935 Schweitzer... 200/52 R UX Primary Examiner-James R. Scott Attorney, Agent, or F irm-Weiser, Stapler & Spivak [5 7] ABSTRACT A freezer monitor switch comprising an elongate, hollow tube which is closed at one end and has its other end equipped with a closure. A pair of current carrying leads communicate with the interior of the tube through the closure and terminate interiorly in a pair of spaced contacts. A small quantity of water or other freezable liquid and a slidable, electrically conductive element are retained interiorly of the tube. The switch initially mounts within the freezer with the open end facing upwardly and with the closed end positioned downwardly until such time as the water freezes and secures the conductive element at the closed end of the tube. The switch is then rotated through 180 within the freezer and is positioned with the frozen in place conductive elements above the contacts. Should the freezer fail for any reason, the water will melt to thereby release the conductive element which falls by gravity and bridges the space between the conductive contacts. Preferably, the electrical leads and contacts form parts of an alarm circuit which will be energized upon contact of the conductive element with the pair of spaced contacts.

5 Claims, 9 Drawing Figures llll' PATENTED JUL 2 2 ms FIG.'! H63 FREEZER MONITOR THERMAL RESPONSIVE SWITCH WITH GRAVITY ACTUATED PLUNGER CONTACT RETAINED BY FREEZABLE LIQUID IN OPEN SWITCH POSITION BACKGROUND-OF THE INVENTION The present invention relates generally to the field of warning devices, and more particularly, is directed to a switch and alarm system suitable to signal operational failure of a freezer.

The use of freezers of both the residentialtype and the commercial type has become increasingly popular and more and different types of food are being stored in frozen condition both in supermarkets and in the home. The frozen food industry has grown rapidly in recent years and there is every indication that its popularity will continue to increase at an undiminished rate.

' By employing the techniquesdeveloped in the frozen experience has shown that freezers, just as any other type of mechanical equipment are subject to unexpected failures due to any number of mechanical or electrical reasons. In those establishments wherein persons are normally actively engaged in the vicinity of the freezer, such freezer failure is usually rapidly observed and such measures as may be necessary to preserve the integrity of the frozen food can be taken. However, in many instances, freezers are located in relatively deserted areas and so a failure could go undetected for a relatively long period of time. In other instances, freezer failure could occur during the evening hours so that such a malfunction would not be normally observed until the following morning. Under such conditions, the frozen food could defrost and even spoil to thereby negate any'advantage previously obtained by maintaining the food in frozen condition.

Prior workers in the art have attempted to develop some type of warning device to visually indicate when the desired temperature conditions within a freezer are not maintained. The devices disclosed in US. Pat. Nos. 3,518,961, 3,618,558 and 3,461,834 are exemplary of prior art warning devices. These devices have generally proved unsatisfactory in that they did not also provide for a reliable, easily installed audible alarm system.

SUMMARY OF THE INVENTION The present invention relates to a novel freezer monitor switch, and more particularly, is directed to a tubular type of switch member having a freezable liquid therein which acts to retain a conductive element in spaced relationship above a pair of alarm circuit contacts. I

The present invention includes a generally hollow tubular member which is closed atone end and has its second end closed by a closure such as a stopper which carries a pair of electrical conductors. The conductors terminate interiorly of the tubular member in apair of spaced contacts. Within the tubular member is retained a small quantity of freezable liquid such as water and a movable switch part which may be in the form of a conductive element which is configured to be slidable within the interior of the tubular member.

A spring bracket retains the freezer monitor switch within a freezing compartment and initially, the freezer monitor switch is positioned with the closed end facing downwardly and with the conductor equipped end facing upwardly. The conductive element falls by gravity within the tubular member and is associated with the freezable liquid at the closed end. By maintaining the switch in this position within the freezing compartment until the liquid freezes, the conductive element is then secured at the closed end of the freezer monitor switch. After the conductive element has been so frozen, the switch is then rotated through relative to the bracket within the freezer compartment so that the closed end positions upwardly with'the frozen water and the entrapped conductive element retained in vertical alignment above the spaced contacts. An electrical circuit preferably containing audible alarm and perhaps also a visual alarm connects to the conductors and to a conventional source of electrical energy, such as a battery or a conventional source of electrical energy, such as a battery or a conventional duplex receptacle. Under normal conditions, no current is open between the pair of spaced contacts which are positioned within the tubular member. Should freezer failure occur, the ice which had been frozen within the tubular member will melt and thereby release the conductive element. Once released, the conductive element falls by gravity within the tubular member and falls directly upon the spaced contacts. The conductive element bridges the opening across the spaced contacts to thereby complete the electrical circuit and allow the flow of current therein. Current flow within the electrical circuit will then activate the audible or visiblealarm signal to alart interested parties to the fact that the freezer had malfunctioned. Once alarted, proper corrective action can be taken in due time to prevent spoilage of the frozen food.

It is therefore an object of the present invention to provide an improved freezer monitor switch of the type set forth.

It is another object of the present invention to. provide a novel freezer monitor switch which incorporates a tubular body and an electrically conductive element slidable within the tubular body, said conductive element being retained in a circuit open position when the freezer is properly operated and said element falling by gravity to a circuit closed position to activate an alarm signal upon failure of the freezer.

It is another object of the present invention to provide a novel freezer monitor switch which incorporates a hollow tubular body having one closed end and one open end, the said open end being equipped with a closure and a pair of electrical conductors, the said conductors terminating interiorly of the tubular body to form a pair of switch contacts and electrically conductive means retained within the tubular member and arranged to engage the contacts upon failure of the freezer mechanism.

It is another object of the present invention to pro vide a novel freezer monitor switch that is inexpensive in manufacture, automatic in operation and trouble free when in use.

Other objects and a fuller understanding of the invention will be had by referring to the following description and claims of a preferred embodiment thereof, taken in conjunction with the accompanying drawings wherein likereference characters refer to similar parts throughout the several views and in which:

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a refrigerating device containing a freezer compartment, partially broken away to show an interior mounted freezer monitor switch.

FIG. 2 is an enlarged, perspective view of a freezer monitor switch constructed in accordance with the present invention.

FIG. 3 is a side elevational view of the freezer monitor switch of FIG. 2 in a first position, partially broken away to expose details of interior construction.

FIG. 4 is a view similar to FIG. 3 showing the freezer monitor switch in second position after the conductive element has been frozen in position and partially broken away to expose details of interior construction.

FIG.'5 is a view similar to FIG. 4 showing the conductive element in circuit closing position and partially broken away to expose details of interior construction.

FIG. 6 is a schematic electrical diagram of the alarm circuit.

FIG. 7 is an enlarged, perspective view of a modified conductive element.

FIG. 8 is an enlarged, perspective view of a second modified conductive element.

FIG. 9 is an enlarged, perspective view of a third modified conductive element.

SUMMARY OF THE PREFERRED EMBODIMENT OF THE INVENTION Although specific terms are used in the following description for the sake of clarity, these terms are intended to refer only to the particular structure of our invention selected for illustration in the drawings and are not intended to define or limit the scope of the invention.

Referring now to the drawings, we show in FIGS. 2-5

-a freezer monitor switch generally designated 10 which preferably is fabricated with an elongated,hollow body 12 having a closedend 14 and anopen end 16. Thehollow body 12 contains a small quantity of afreezable liquid 18, such as water, which serves to retain the conductive element at the closedend 14 of thehollow body 12 when in use as hereinafter more fully set forth.

A watertight closure 22, which may be fabricated of rubber, plastic or other waterproof and electrically non-conductive material, is a force fit into theopen end 16 of thehollow body 12 to provide a closure therefore. A pair ofconductors 24, 26 insert through theclosure 22 in a conventional, leakproof manner and terminate within the hollow bodyinterior space 28 in a pair 1 of similar, spaced,electrical contacts 30, 32. Theelectrical contacts 30, 32 project interiorly of the interior surface ofthe closure 22 a sufficient distance to receive theconductive element 20 in an electrically conductive engagement without interference from the closure material itself.

As best seen in FIGS. 3, 4 and 5, theconductive element 20 includes anelongated body 36 and anintegral contact head 38 which is sized to readily slide within theinterior space 28 defined within thehollow body 12. The elongated nature of theconductive element body 36 serves to orient the longitudinal axis of theconductive element 20 with the longitudinal axis of thehollow body 12 to prevent binding therein and to assure positive electrical engagement between thecontact head 38 and the pair of spacedelectrical contacts 30, 32 when the switch is activated. In the embodiment illustrated, thehead 38 is shown of relatively discoid configuration to ride within the cylindrical configuration of thehollow body 12.

As seen in FIGS. 1 and 2, a mountingbracket 44 mounts within thefreezer compartment 46 and is provided with a pair of outwardly projectingspring arms 48, 50. The spring arms are provided with sufficient spring tension to readily receive and hold thehollow body 12 when the freezer monitor switch is gently pushed into the open space 52which is defined between thespring arms 48, 50.

As illustrated in FIG. 6, theelectrical conductors 24, 26.form part of an electrical series-circuit 54 including the pair ofterminals 56, 58 which are connected in well known manner to a source of electrical energy (not shown) such as a conventional battery or a conventional duplex receptacle. Analarm bell 60 connects in series in thecircuit 54 in a manner to be energized when current flows within the circuit. As illustrated, thefreezer monitor switch 10 serves as the circuit switch and accordingly when the conductive-element 20 is maintained out of contact with theelectrical contacts 30, 32, such as by the function of the ice 62 (FIG. 4) which is produced by freezing thewater 18, thecircuit 54 will be open and no electrical current will flow. Should theice 62 melt to thereby release theconductive element 20, theswitch 10 will close to thereby permit the flow of electrical current through thecircuit 54 to activate thebell 60 or any other type of conventional alarm device which is wired into the circuit.

In order to operate the freezer monitor switch of the present invention, the mountingbracket 44 is positioned within thefreezer compartment 46 in a convenient location to permit access thereto. Then the freezer monitor switch is placed interiorly of thefreezer compartment 46 by associating it with the mountingbracket 44 and by orienting the switch with theclosed end 14 facing downwardly as in FIGS. 2 and .3. Thefreezer monitor switch 10 is maintained within the freezer compartment a sufficient length of time to freeze thewater 18 to ice 62 to thereby entrap theconductive element 20 in a position near theclosed end 14. Upon freezing of thewater 18, thefreezer monitor switch 10 is then removed from its association with the a source of electrical energy (not shown)- to power thecircuit 54. In this condition, thefreezer monitor switch 10 is set to detect any malfunction in the freezer operation of sufficient magnitude to cause loss of the freezing atmosphere within thecompartments 46 to melt theice 62. Should the freezer fail and theice 62 melt, theconductive element 20 which was previously frozen in position associated with theclosed end 14 by action of theice 62 is then free to fall within theinterior space 28 defined within thehollow body 12 until theconductive element 20 contacts the pair of spacedelectrical contacts 30, 32 to thereby complete theelectrical circuit 54 which activates thealarm device 60.

Referring now to FIG. 7, we shown a modifiedconductive element 20 wherein theelement body 36 is provided with a plurality of radially outwardly directed pins 42 which are in spaced relation to thecontact head 38. The pins terminate outwardly at the projected perimeter of thecontact head 38 to readily slide within thehollow body 12. The spaced relationship between thepins 42 and thecontact head 38 serves to assure longitudinal alignment of theelement body 36 within thehollow body 12 at all times. Similarly, in FIG. 8, a

seconddiscoid element 38" is provided in spaced relation from thecontact head 38 to assure longitudinal alignment of the second modified conductive element" Referring to FIG. 9, a third modifiedconductive element 20 is illustrated wherein theelement body 36" is formed to cylindrical configuration of diameter slightly smaller than the interior diameter of thehollow body 12 to thereby encourage longitudinal movement without the possibility of longitudinal alignment. In this modification, thecontact head 38" is simply the bottom face of the conductive cylinder.

Although we have described the present invention with reference to the particular embodiments herein set forth, it is understood that the present disclosure has been made only by way of example and that numerous changes in the details of construction may be resorted to without departing from the spirit and scope of the invention. Thus, the scope of the invention should not be limited by the foregoing specification, but rather only by the scope of the claims appended hereto.

We claim:

1. In a freezer monitor switch positioned within a freezer, the combination of A. a hollow body having one closed end and one closed contact containing end;

B. an electrically conductive element positioned within the body, r

l. the conductive element comprising an elongated body and a contact head, the contact head having a diameter to readily slide within the hollow body,

2. said element being movable from a first position to a second position, the first position being above the second position; C. a quantity of freezable liquid contained within th body;

a. said liquid being frozen to a solid state by operation of the freezer,

b. the said liquid when in the solid state maintaining the element in its first position,

0. the said liquid melting to the liquid state upon freezer failure to release the element,

d. the element falling by gravity from the first position to the second position upon freezer failure;

D. a pair of spaced electrical contacts positioned at the contact containing end,

1. the contacts extending into the interior space,

2. the said element being positioned at the closed end and spaced from the contacts when in the first position,

3. the said element contacting both of the electrical contacts and forming an electrically conductive path therebetween when the element is moved to its said second position,

E. a bracket mounted interiorly of the freezer,

1. said hollow body being removably mounted on the bracket,

2. the hollow body being initially mounted within the freezer with the closed end down and the contact containing end up,

3, the said freezable liquid and conductive element initially falling to the said closed end and the action of the freezer freezing the liquid and entrapping the conductive element at the closed end,

4. the hollow body being then removed from the bracket and being rotated through within the freezer after the liquid is frozen to position the closed end vertically above the contactcontaining end and being remounted on the bracket.

2. The invention of claim 1 wherein the conductive element includes means to maintain the conductive element in axial alignment withinithe hollow body.

3. The invention of claim 2 wherein the means comprise a plurality of pins which extend outwardly from the elongated body, said pins being spaced from the contact head.

4. The invention of claim 2 wherein the means comprise a disc connected to the elongated body, said disc being spaced from the contact head.

5. The invention of claim 1 wherein the conductive element comprises a body of cylindrical configuration, said body having a diameter slightly smaller than the interior diameter of the hollowbody.

Claims (10)

1. In a freezer monitor switch positioned within a freezer, the combination of A. a hollow body having one closed end and one closed contact containing end; B. an electrically conductive element positioned within the body, 1. the conductive element comprising an elongated body and a contact head, the contact head having a diameter to readily slide within the hollow body, 2. said element being movable from a first position to a second position, the first position being above the second position; C. a quantity of freezable liquid contained within the body; a. said liquid being frozen to a solid state by operation of the freezer, b. the said liquid when in the solid state maintaining the element in its first position, c. the said liquid melting to the liquid state upon freezer failure to release the element, d. the element falling by gravity from the first position to the second position upon freezer failure; D. a pair of spaced electrical contacts positioned at the contact containing end, 1. the contacts extending into the interior space, 2. the said element being positioned at the closed end and spaced from the contacts when in the first position, 3. the said element contacting both of the electrical contacts and forming an electrically conductive path therebetween when the element is moved to its said second position, E. a bracket mounted interiorly of the freezer, 1. said hollow body being removably mounted on the bracket, 2. the hollow body being initially mounted within the freezer with the closed end down and the contact containing end up, 3, the said freezable liquid and conductive element initially falling to the said closed end and the action of the freezer freezing the liquid and entrapping the conductive element at the closed end, 4. the hollow body being then removed from the bracket and being rotated through 180* within the freezer after the liquid is frozen to position the closed end vertically above the contact containing end and being remounted on the bracket.

2. said element being movable from a first position to a second position, the first position being above the second position; C. a quantity of freezable liquid contained within the body; a. said liquid being frozen to a solid state by operation of the freezer, b. the said liquid when in the solid state maintaining the element in its first position, c. the said liquid melting to the liquid state upon freezer failure to release the element, d. the element falling by gravity from the first position to the second position upon freezer failure; D. a pair of spaced electrical contacts positioned at the contact containing end,

2. the said element being positioned at the closed end and spaced from the contacts when in the first position,

2. The invention of claim 1 wherein the conductive element includes means to maintain the conductive element in axial alignment within the hollow body.

2. the hollow body being initially mounted within the freezer with the closed end down and the contact containing end up, 3, the said freezable liquid and conductive element initially falling to the said closed end and the action of the freezer freezing the liquid and entrapping the conductive element at the closed end,

3. The invention of claim 2 wherein the means comprise a plurality of pins which extend outwardly from the elongated body, said pins being spaced from the contact head.

3. the said element contacting both of the electrical contacts and forming an electrically conductive path therebetween when the element is moved to its said second position, E. a bracket mounted interiorly of the freezer,

4. The invention of claim 2 wherein the means comprise a disc connected to the elongated body, said disc being spaced from the contact head.

4. the hollow body being then removed from the bracket and being rotated through 180* within the freezer after the liquid is frozen to position the closed end vertically above the contact containing end and being remounted on the bracket.

5. The invention of claim 1 wherein the conductive element comprises a body of cylindrical configuration, said body having a diameter slightly smaller than the interior diametEr of the hollow body.

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