US2764874A

US2764874A - Refrigerator door fastener

Info

Publication number: US2764874A
Authority: US
Inventors: Verlos G Sharpe
Original assignee: Motors Liquidation Co
Current assignee: Motors Liquidation Co
Priority date: 1954-08-17
Filing date: 1954-08-17
Publication date: 1956-10-02
Anticipated expiration: 1973-10-02

Description

Oct. 2, 1956 v. G. SHARPE REFRIGERATOR DOOR FASTENER 3 SheetsSheet 1 INVENTOR.

' izfosGJZzyoe.

Filed Aug. 17, 1954 HIS ATTQRNEY.

Oct. 2, 1956 v. G. SHARPE 2,764,874

REFRIGERATOR DOOR FASTENER Filed Aug. 17, 1954 5 Sheets-Sheet 2 19.9 if INVEN TOR.

er/0s @jl ar c-t B Y HIS ATTORNEY.

Oct. 2, 1956 v. e. SHARPE 2,

REFRIGERATOR DOOR FASTENER Filed Aug. 17, 1954 3 Sheets-Sheet 3 K2 89 i' 5/ as INVENTOR.

5 72 BY VezZos G hzqve HYIS' ATTORNEY.

REFRIGERATOR DOOR FASTENER Yerlos G. Sharpe, Dayton,

Motors :Corporation, Delaware Application August 17, 1954, Serial No. 450,305

-9 Claims. (Cl. 62-4) vOhio, assignor to General Detroit, Mich, a corporation of closing the door after discarding the cabinet whereby a child upon entering the compartment of a discarded refrigerator cabinet readily extricates himself or herself therefrom.

Another object of my invention is to provide a refrigerator door latch .with an improved electrical means which permits the door to be opened and closed in the ordinary manner by manipulating the latch handle on the outside of the door when the refrigerator is being used for the preservation of foods and which means renders the latch inoperative for preventing locking the door tightly closed.

In carrying out the foregoing objects, it is a further and more specific object of my invention to associate an electrically heated thermostatic means with a door latching mechanism of a refrigerator cabinet .or the like, the heater of which is connected in a detachable electric circuit leading from a source of electric current supply to the refrigerator and is continuously energized as long as the refrigerator is employed for preserving foods to permit the latching mechanism to open and/or lock or close the door with a strong force and which heater is deenergized upon or in response to disconnecting the detachable electric circuit of the refrigerator from the current supply for rendering the latching mechanism inoperative for locking the door closed while at the same time permitting latching of the door to the cabinet with a relatively small force easily overcome by applying pres sure to the door.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawings wherein a preferred form of the invention is clearly shown.

In the drawings:

Figure 1 is a vertical fragmentary sectional view through a door and door jamb of a refrigerator cabinet having my improvement therein and showing the door latching mechanism holding the door tightly latched against the cabinet;

'Figure '2 is a view similar to Figure 1 and shows a keeper element of the latch entering the locking or holding mechanism portion thereof;

Figure 3 is a view similar to Figures 1 and 2 and shows the jaw-like device of the latching mechanism blocked open by a thermostat means and the door latched to the cabinet with a small force;

Figure 4 is a fragmentary sectional view taken on the line 4-4 of Figure 3 showing a blocking pin in the tates Patent "Patented Oct. 2, .1956

ICE

2 path of movement :of an arm of the door "latching mechanism;

Figure 5 is .a'fragmentary sectional view'taken on line 5-5 of Figure .2 showing the blocking pin moved out of the path of movement of anarm of the latching mechanism;

Figure 6 is a fragmentary sectional view taken on the line 66 of Figure '2 showing the relationship of 7 parts of the latch mechanism;

Figure 7 is a fragmentary sectional view taken on the line 77 of Figure 2 showing rollers on the jaw-like device portion of the latch mechanism;

Figure 8 is a fragmentary sectional view taken .on the "line 8-8 ofFigure 3 .showinganarm of 'theilatch mechanism blocked by the latch'blocking pin; and

Figure '9 is a diagrammatic showing of a detachable electric circuit associated 'with a refrigerator having my invention incorporated therein.

Referring to the drawings, 'for illustrating my invention, I show in Figure 1 thereof an insulated side wall 11 :of a refrigerator cabinet structure having a door fjanib provided with a flat surface .or panel 12 at the front of the cabinet adjacent to an access opening leading .to a food storage compartment provided in the cabinet. A door structure, generally represented by the reference character 14, has an outer surface of metal panel 15 spaced from an inner panel (not shown) .and insulating material '16 is disposed between the door panels. One side of door structure '14 is 'hingedly mounted upon the refrigerator cabinet structure for horizontal swinging movement relative thereto and is adapted tojhave its other sidefastened or locked to the cabinet. Door14'is formed with an edge portion overlapping the door janib front .surface 12 of the cabinet and has a resilient compressible rubber-like gasket 17 mounted thereon in any suitable manner for sealingly engaging the cabinet surface 12 to close the food storage compartment in a substantially air-tight manner all of which is conventional in the 'art and readily understood by those skilled therein.

The fastening means for locking door structure .14 tightly closed against the refrigerator cabinet structure to seal the food compartment access opening comprises a latch mechanism including a rigid metal keeper part or element 21 having its one end '22 pivotally mounted in the door jam'b of the refrigerator cabinet upon a pin 23 and provided with an arrowhead-shaped outer end .24 cut back as at 26 to provide a hook thereon. ,End 22 of keeper element 21 is provided with an off-set extension carrying a stud 27. A spring 28, coiled about stud 23, has its two ends normally engaging a stud 29 stationarily mounted on the refrigerator cabinet and tends to bias the keeper element 21 into a desired neutral position. Keeper element 21 projects through a suitable slot provided in the wall surface 12 of the cabinet door jamb and is adapted to extend through a suitable slot provided in panel 15 of door 14. The latchingmechanism includes another part mounted on door 14 for receiving and interlockingly engaging the keeper element 21. This other part of the latch mechanism is located in a U-shaped metal box or frame structure within .door 14 and secured to panel 15 thereof in any suitable or desirable manner. The U-shaped frame structure or mechanism housing includes two upright side walls 31 and an integral lower connecting wall 32. One of the side walls 31 is broken away to more clearly show elements of this other part of the latch mechanism. A plurality of stationary shafts or

studs

33, 34, 35 and 36 are riveted to the side walls 31 of the metal frame structure and form a rigid tie therebetween. The lower end of a metal arm 37, having an elongated opening 38 therein fitting over stud 33, -:extends through a slot 39 provided in the horizontal bottom wall 32 of the latch frame or housing.

Arm 37 carries the toggle-joint contrivance of a shaft or stud 41 and a strong coil spring 42 surrounds arm 37 and is held compressed between the shafts or studs 33 and 41. The upper end of arm 37 has a shaft or stud 43 thereon carrying a roller 44. An inverted U-shaped arm 46 is pivotally mounted on stationary shaft or stud 34 and has its one end 47 pivotally attached to the shaft or stud 41 carried on arm 37. The other end 48 of arm 46 carries a stud 49 upon which is mounted two depending sheet metal pieces 51 spaced apart by a roller 52 also mounted on stud 49. These depending metal pieces 51 are each provided with a vertically elongated opening 53 fitting over the stationary stud 36 and an integral off-set portion 54 carries a stud 55. A roller 56 is mounted on stud 36 intermediate the lower ends of metal pieces 51. Another stud 50 riveted to arm 46 has a U-shaped trigger or lock member 57 pivotally mounted thereon. Lock member 5 7 is adapted to rest against stationary stud 35 (see Figure 2) and a spring 58 coiled around shaft or stud 50 has its one end engaging arm 46 and its other end bearing against member 57 to bias the stop or trigger member 57 toward stud 35. The

arms

37 and 46 together with their mountings on the studs 33 and 34 and their cooperation with one another form a cockable and trippable toggle-joint contrivance. The arm 46 together with

rollers

52 and 56 provide the latch mechanism with a movable jaw-like device. Trigger member 57 when engaging stud 35 locks both the toggle-joint contrivance and the jaw-like device of the latch mechanism and must be released from this stud to permit operation of the mechanism.

When the door structure 14 is closed to lock the door against the refrigerator cabinet and to compress gasket 17 into tight sealing engagement with panel or surface 12 (see Figure 1) the toggle-joint contrivance is released by keeper element 21 and the jaw-like device of the mechanism is closed upon keeper 21 under the influence of the strong spring 42. In order to open door 114 spring 42 must be compressed to permit moving or opening of the aw-like device of the latch from the position thereof shown in Figure 1 of the drawings to the position shown in Figure 2. Spring 42 is compressed and the toggleioint contrivance is cocked open by a series of levers extending through door structure 14 and connected to a latch handle (not shown) located on the exterior side of the door. Any conventional leverage linkage extendlmg from the handle on the outside of door 14 may engage or be suitably connected to a lever 61 pivotally I mounted upon a stud 62 riveted to upstanding ears 63 on the upright sides 31 of the U-shaped latch housing or frame for swinging the short end of this lever 61 into engagement with the roller 44 to move arm 37 downwardly and to compress spring 42. Such downward movement of arm 37 causes arm 46 to pivot about stud 34 whereupon the end 48 of arm 46 will be elevated rela tive to the position thereof shown in Figure 1 to its position shown in Figure 2. As the end 48 of arm 46 moves upward it carries the metal pieces 51, roller 52 and movable stud 55 upwardly. Stud 55 engages the underside of end 24 of keeper element 21 to tilt same about pin 23 whereupon the hook 26 on element 21 is moved into a position (see Figure 3) to be passed over stationary roller 56. Keeper element 21 having been released from the jaw-like device,

rollers

52 and 56, of the latch mechanism a forward pull on door 14 will now ride the underside of end 24 of element 21 over roller 56 and permit door 14 to open for affording access to the food storage compartment within the refrigerator cabinet. As the end 24 of keeper 21 moves out of the jaw-like device portion of the latch mechanism spring 58 rotates trigger or lock member 57 into engagement with stud 35 to lock the latch mechanism in the position thereof shown in Figure 2 of the drawings. Upon closing door 14 the widestportion of the inclined element 21 will enter the jaw-like device to move roller 52 upwardly relative to roller 56 and arm 46 consequently lifts trigger or stop member 57 off stud 35. Continued closing movement of door 15 causes the end 24 of keeper element 21 to move member 57 away from stud 35. At this moment the toggle-joint contrivance is tripped or released and the strong force of spring 42 causes the jaw-like device,

rollers

52 and 56, of the mechanism to close and lock upon keeper 21 (see Figure 1). The inclination of hook 26 on keeper element 21, riding over roller 56, draws or compresses the gasket 17 tightly between the cabinet structure and the door structure 14 (see Figure 1). Door 14 remains tightly locked against the cabinet and it cannot be opened by force applied thereto unless the exterior latch handle is again manipulated to force open the latch mechanism. The construction of the latch mechanism thus far disclosed and its action is conventional, is normal and is presently employed on the food storage compartment door of refrigerator cabinets obtainable on the open market. .It should therefore be obvious that if a child would enter the food compartment of a refrigerator cabinet provided with the latch mechanism as described and the door 14 then be closed the child would be trapped in the cabinet with no means of extricating himself or herself therefrom.

The present conventional door latch is highly desirable and practical particularly from the standpoint of being capable of compressing the door gasket and providing a tight uniform seal about the food storage compartment access opening. I, therefore desire to modify this type of latch mechanism to overcome the hazard of a child being trapped in a discarded refrigerator cabinet equipped with a latch of the present type. In accordance with my invention I modify the conventional latch mechanism disclosed for accomplishing the objects hereinbefore set forth by associating an electrically heated thermostatic means therewith. This thermostatic means includes a strip of bimetal having its one end secured to a block 66 of insulating material mounted, as by a screw or rivet 67, upon an upright side wall 31 of the U-shaped latch housing. An electric resistance wire heater element 68 secured in heat-exchange relationship, in any suitable or conventional manner, with the bimetal strip 65 is adapted to apply heat thereto. The free end of bimetal strip 65 has a blocking pin 63 carried thereon and this pin extends through a hole provided in a guide or bearing piece 71 suitably mounted on wall 31 of the latch housing. Pin 69 also extends through a hole 72 provided in a side wall 31 of the latch housing (see Figure 8). Pin 69 is so located as to be moved, by the bimetal strip 65, into the downward path of movement of arm 46 when this arm is in its upper position or when the latch mechanism is cocked open in a manner and for a purpose to be hereinafter described. Heater element 68 forms a part of a detachable electric circuit connected to a source of electric current supply and extending therefrom to an electrically operated refrigerant translating unit such, for example, as a motor-compressorcondenser unit of a closed refrigerating system associated with the refrigerator cabinet. This circuit comprises the detachable extension electric cord supplied with a refrigerator and plugable into a Wall or the like receptacle connected to a source of electric current for rendering the refrigerating system in the cabinet operative. The closed refrigerating system also includes a refrigerant evaporator (not shown) for cooling the interior of the food storage compartment of the refrigerator cabinet and suitable conduits interconnecting the refrigerant translating unit with the evaporator.

side of the motor Winding of unit 76 is connected by wire 79 to a thermostatic switch-81 and to the-otherwire 82 of the detachable electric circuit or extension cord of the refrigerator. Thermostatic switch 81 controls starting and stopping of unit 76 in response to temperatures within the food storage compartment of the refrigerator as is common in the art. The detachable electric circuit may also include a food compartment illuminating lamp 83 and a door operated switch 84 therefor connected across the

wires

77 and 82 by branch wires v86 and 87 for energizing and deenergizing lamp 83 in response to opening and closing door 14 as is also common in the art. The remainder of this detachable circuit comprises the resistance winding of heater 68 connected across wires 77 and 82by the

branch wires

88 and 89. Heater 68 is continuously energized when the detachable circuit, with unit 76 and lamp 83 therein,.is connected to a source of electric current supply .for rendering the refrigerating system operative. Heat dissipated by heater 68 causes bimetal strip 65 to bow in a direction outwardly away from the wall 31 of the latch housing into the position thereof shown in Figure 5 to hold the blocking pin 69 out of the path of movement of arm 46 of the door latching mechanism. The electric heater 68 is designed to, say, for example, heat the bimetal thermostat strip to approximately 150 F. under a usage of electric current of from 2 to 2 /2 amperes. If the detachable cord just described is disconnected from the source of electric current for any reason the thermostat means associated with the latch mechanism will, in response thereto, move blocking pin 69 from the position thereof shown in Figure 5 of the drawings to the position shown in Figure 4. Disconnecting this detachable circuit causes electric heater 68 to be deenergized whereupon bimetal strip 65 will cool to room temperature and will have a tendency to bow back into its normal position shown in Figure 4. However, the jaw-like device of the latching mechanism may at this time be clamped upon the element 21 maintaining door 14 tightly closed as shown in Figure l and pin 69 will therefore abut against a side of arm 46 to thus be ineffective for blocking movement of arm 46 at this time. A subsequent opening of door 14-, by manipulating the latch handle on the exterior of the door to move the latch mechanism into the cocked position thereof as shown in Figure 2, swings the end 48 of arm 46 upward beyond pin 69 whereupon this pin will now, by being biased by the cooled bimetal strip 65, be shifted into a position below one side of arm 46 (see Figures 3 and 4). This renders the toggle-joint contrivance and the jaw-like device portions of the latch mechanism incapable of being tripped into a locked or tightly closed position on keeper element 21 upon now closing door 14 after the subsequent opening thereof. Therefore if the refrigerating system associated with the refrigerator cabinet is rendered inoperative forstoring the refrigerator or if an old refrigerator cabinet is to be discarded the disconnecting of the detachable circuit from a source of electric current provides a positive means of preventing locking or tightly closing door 14 to the cabinet after the subsequent opening of the door as just described. Thus, if a child should enter the food compartment of the refrigerator after this subsequent opening of the compartment door 14 and the door then closed, the latching mechanism is ineffective to hold the door locked. The arrowhead-shaped end 24 of keeper element 21 will enter the jaw-like device of the mechanism upon closing door 14 to move the lock 57 off stud 35 but blocking pin 69, being engaged by arm 46, prevents closing of the jaw-like device upon keeper 21 and compression of gasket 17 between the door and the refrigerator cabinet while permitting the door to be lightly latched to the cabinet as shown in Figure 3 of the drawings. In lightly latching door 14 to the refrigerator cabinet it will be noted that the top of hook portion 26 on keeper element 21 has ridden over the stationary roller means of escape.

-56 and has come torest on stud.55. .By virtue of .the

latchingmechanism being .lockedopen theloweritip of hook portion 26 on keeper -21 may be readily moved ba'ckoverthe top of .roller56 with a small force applied to door 14 and without actuating the latch handle on the outside of this door. A small force, capable of being exerted by a child trapped in the refrigerator cabinet, applied directly tothe door from within the cabinet, will move the keeper element portion 21 of the latch mechanism out of the jaw-like device portion thereof and cause the door to swing open about its hinge mounting. When this force is applied to door 14 keeper element 21 tilts upwardly about its pivotal mounting stud 23 against the tension of light spring 28. Thus a latching mechanism for a door of a refrigerator cabinet which becomes inoperative to hold the door locked in closed position when the refrigerator is disconnected from a source of electric current and is to be stored or discarded is provided to insureagainst a child becoming trapped therein without Locking of door .14 to the refrigerator cabinet as herein employed is to be distinguished from locking the door with a key or thelike. As herein employed locking of door 14 is the normal closing of the door which tightly compresses gasket 17 to insure seal- .ingof the food compartment access opening and which latches the door shut against being opened by pressure applied thereto by the compressible gasket.

,asource of electric current. My improvement permits .latching of a door to a refrigerator cabinet with a light force capable ofbeing overcome by a child trapped in the cabinet and which permits the door to be retained in closed position during storing of the cabinet. The thermostat means employed in the latch mechanism for the refrigerator cabinet .door as herein disclosed is heated to a high temperature above any temperatures ambient to the cabinet and ordinarily encountered so that the mechanism will not become reeffective to hold the door locked tightly to the cabinet after an old refrigerator cabinet has been discarded and exposed to rays of the sun.

While the form of embodiment of the invention as herein disclosed constitutes a preferred form, it is to be understood that other forms might be adopted, as may come within the scope of the claims which follow.

What is claimed is as follows:

1. In a refrigerator or the like, a cabinet structure having a compartment therein provided with an access opening and a door structure adapted to close same, a closed refrigerating system associated with said cabinet structure including a refrigerant evaporator for cooling the interior of said compartment and an electrically operated refrigerant translating unit, an electric circuit detachably connected to a source of electric current and leading therefrom to said unit, fastening means for said door structure, said fastening means comprising a mechanical manually operable latch mechanism having means for holding said door locked in closed position, and thermostatic means responsive to disconnecting said detachable circuit from said source of electric current for rendering said manually operable latch mechanism ineffective to hold said do'or locked. i

2. In a refrigerator or the like, a cabinet structure having a compartment therein provided with an access opening and a door structure adapted to close same, a closed refrigerating system associated with said cabinet structure including a refrigerant eva .orator for cooling the interior of said compartment and an electrically operated refrigerant translating unit, an electric circuit detachably connected to a source of electric current and leading therefrom to said unit, fastening means for said door structure, said fastening means comprising a mechanical manually operable latch mechanism having means for holding said door locked in closed position, a handle accessible from the exterior of said structures for opening said latch mechanism and unlocking said door, and thermostatic means responsive to disconnecting said detachable circuit from said source of electric current for preventing closing of said manually operable latch mechanism.

3. In a refrigerator or the like, a cabinet structure having a compartment therein provided with an access opening and a door structure adapted to close same, a closed refrigerating system associated with said cabinet structure including a refrigerant evaporator for cooling the interior of said compartment and an electrically operated refrigerant translating unit, an electric circuit detachably connected to a source of electric current and leading therefrom to said unit, fastening means for said door structure, said fastening means comprising a mechanical manually operable latch mechanism having means for holding said door locked in closed position with a strong force and for latching said door closed with a relatively small force, a handle for releasing said strong force of said latch mechanism, and thermostatic means associated with said manually operable latch mechanism responsive to disconnecting said detachable circuit from said source of electric current for rendering the latch mechanism door locking means ineffective to hold said door locked and effective to latch said door closed with said small force.

4. In a refrigerator or the like, a cabinet structure having a compartment therein provided with an access opening and a door structure adapted to close same, a closed refrigerating system associated With said cabinet structure including a refrigerant evaporator for cooling the interior of said compartment and an electrically operated refrigerant translating unit, an electric circuit detachably connected to a source of electric current and leading therefrom to said unit, fastening means for said door structure, said fastening means comprising a mechanical manually operable latch mechanism having means for holding said door locked in closed position, a handle for actuating said latch mechanism to unlock said door, a thermostat associated with said latch mechanism, an electric heater having a connection with said circuit for heat ing said thermostat and normally maintaining said latch mechanism door locking means operable by said handle, and said thermostat being responsive to disconnecting said detachable circuit from said source of electric current for rendering said manually operable latch mechanism door locking means ineffective to hold said door locked whereby the door is openable by a force applied directly thereto.

5. In a refrigerator or the like, a cabinet structure having a compartment therein provided with an access opening and a door structure adapted to close same, a closed refrigerating system associated with said cabinet structure including a refrigerant evaporator for cooling the interior of said compartment and an electrically operated refrigerant translating unit, an electric circuit detachably connected to a source of electric current and leading therefrom to said unit, fastening means for said door structure, said fastening means comprising a mechanical manually operable latch mechanism for holding said door locked in closed position, a thermostat associated with said latch mechanism, an electric heater having a connection with said circuit for heating said thermostat, and said thermostat being responsive to disconnecting said detachable circuit from said source of electric current for rendering said manually operable latch mechanism ineifective to hold said door locked.

6. In a refrigerator or the like, a cabinet having a compartment therein provided with an access opening and a door adapted to close same, a closed refrigerating system associated with said cabinet including a refrigerant evaporator for cooling the interior of said compartment and an electrically operated refrigerant translating unit, an electric circuit detachably connected to a source of electric current and leading therefrom to said unit, fastening means for said door, said fastening means comprising a keeper element mounted on said cabinet and a mechanical manually operable latch mechanism carried by said door, said latch mechanism including a keeper engaging means for holding said door locked in closed position, thermostatic means associated with said latch mechanism and having a connection with said circuit, and said thermostatic means being responsive to disconnecting said detachable circuit from said source of electric current for rendering said keeper engaging means of said manually operable latch mechanism ineffective to hold said door locked whereby the door upon applying a pressure directly thereto will open.

7. In a refrigerator or the like, a cabinet structure having a compartment therein provided with an access opening and a door structure adapted to close same, a closed refrigerating system associated with said cabinet structure including a refrigerant evaporator for cooling the interior of said compartment and an electrically operated refrigerant translating unit, an electric circuit detachably connected to a source of electric current and leading therefrom to said unit, fastening means for said door structure, said fastening means comprising a mechanical manually operable latch mechanism on one of said structures and a keeper element on the other of said structures, said latch mechanism having a keeper engaging device, said keeper engaging device being movable by said keeper element into locking engagement therewith upon closing said door, a handle accessible from the exterior of said structures for moving said keeper engaging device out of locking engagement with said keeper element to open said door, thermostatic means associated with said latch mechanism, an electric heater having a connection with said circuit for heating said thermostatic means, means associated with said thermostatic means for rendering said keeper engaging device of the manually operable latch mechanism incapable of being locked in locking engagement with said keeper element, and said circuit when detached from said source of electric current causing said thermostatic means to operate said last named means.

8. In a refrigerator or the like, a cabinet structure having a compartment therein provided with an access opening and a door structure adapted to close same, a closed refrigerating system associated with said cabinet structure including a refrigerant evaporator for cooling the interior of said compartment and an electrically operated refrigerant translating unit, an electric circuit detachably connected to a source of electric current and leading therefrom to said unit, fastening means for said door structure, said fastening means comprising a mechanical manually operable latch mechanism having a keeper element on one of said structures and a spring pressed cockable and tripable jaw-like device on the other of said structures adapted to receive said keeper element, said jaw-like device being tripped into locking engagement with said keeper element upon closing said door, a handle outside said structures for cocking said jaw-like device in open position and unlocking said keeper element therefrom to open said door, a thermostat associated with said latch mechanism and having a means engageable therewith, an electric heater for heating said thermostat, said heater having a connection with said circuit, and said thermostat rendering the iawdike device of said manually operable latch mechanism incapable of being tripped into locking engagement with said keeper element in response to disconnecting said detachable circuit from said source of electric current whereby said door can be opened by a pressure applied directly thereto.

9. In a refrigerator or the like, a cabinet structure having a compartment therein provided with an access opening and a door structure adapted to close same, a closed refrigerating system associated with said cabinet structure including a refrigerant evaporator for cooling the interior of said compartment "and an electrically operated refrigerant translating unit, an electric circuit detachably connected to a source of electric current and leading therefrom to said unit, fastening means for said door structure, said fastening means comprising a mechanical manually operable latch mechanism having a keeper element on one of said structures and a keeper engaging device on the other of said structures, a normally effective means for locking said keeper engaging device to said keeper element with a strong force upon closing said door, a handle outside said structures for moving said keeper engaging device out of locked engagement with said keeper element to open said door, thermostatic means as- 15 sociated with said manually operable latch mechanism and having a connection with said detachable electric circuit, said circuit when detached from said source of electric current causing said thermostatic means to render said normally effective means inelfective to lock said keeper engaging device to said keeper element upon a subsequent closing of said door, means on said keeper element engageable with a portion of said keeper engaging device upon said subsequent closing of the door to latch said door to said cabinet with a relatively small force, and said last named means being movable out of engagement with said portion of said keeper engaging device in response 0 to a pressure applied directly to said door.

References Cited in the file of this patent UNITED STATES PATENTS 2,253,252 Smith Aug. 19, 1941 2,584,480 Mantling Feb. 5, 1952 2,662,787 Horvay Dec. 15, 1953