US2405869A - Thermostatic switch - Google Patents

Description

Aug. 13, 1946.

A. WILD THERMOSTATIC SWITCH Filed Jan. 24, 1944 INVENTOR.

Patented Aug. 13, 1946 UNITED STATES PATENT OFFICE THEBMOSTATIC SWITCH Alfred Wild, Milwaukee, Wis.

Application January 24, 1944, Serial No. 519,481

11 Claims. 1

The present invention relates in general to improvements in the art of temperature control, and relates more particularly to improvements in the construction and operation of thermostatic switches for controlling the actuation of electric heaters or the like.

The primary object of this invention is to provide an improved thermostatic switch which is simple and durable in construction, reliable in operation, and flexible in its adaptations and uses.

It is extremely desirable in connection with the operation of electric heaters for diverse purposes, and especially in conjunction with electrically heated flat irons, to have availabl a durable and reliable thermostatic control which i readily adjustable so as to vary the degree of heating. While many different types of such thermostats or thermostatic switches have heretofore been proposed and used with varying degrees of success, most of these prior devices are either relatively complicated in construction, or frail in structure, or not accurately adjustable, or insufficiently sensitive and reliable in operation, or unadapted for diverse uses and especially inplaces where they are subject to jarring and jolting, or relatively costly to manufacture. Many of the prior thermostatic controls are therefore objectionable for one or more of th above reasons and have been a source of considerable annoyance to users thereof.

It is a more specific object of my invention to provide a new and useful thermostatic control device which obviates all of the above mentioned objections and annoyances, and which is simple, sturdy, dependable, and relatively inexpensive.

Another specific object of this invention is to provide an improved thermostat which is adapted for many uses, and especially in portable devices such as fiat irons which are subject to jarring and jolting, Without detrimentally affecting the operation of the thermostat.

A further specific object of the invention is to provide an improved thermostatic switch which may be conveniently and accurately adjusted to control the degree of heat generated by the heater to which it is applied, and all parts of which are readily accessible for inspection.

Still another specific object of the present invention is to provide an improved temperature controlled electric switch assemblage in which the relative position of the fixed and movable contacts may be readily varied, but wherein the contacts are kept clean and most efiective at all times by suitable wiping action.

An additional specific object of my invention is to provide a simple, compact and strong switch assembly which may be manufactured at moderate cost from metal stampings or the like, and which may also be readily assembled, dismantled, or associated with the device or system with which it is to be normally associated.

A further specific object of this invention is to provide an eflicient electric switch which may be adjusted throughout a considerable range, and the actuation of which is controllable by means of a sturdy and reliable lei-metallic element.

These and other objects and advantages of the present invention should be more readily apparent from the following detailed description.

A clear conception of the several features constituting the present invention, and of the construction and operation of my improved thermostatic switch, may be had by referring to the drawing accompanying and forming a part of this specification wherein like reference characters designate the same or similar parts in the various views.

Fig. 1 is a part sectional side elevation of the switch, showing the normally fixed upper contact in its uppermost and inactive position of adjustment and the contacts open;

Fig. 2 is a full side elevation of th same switch, with the upper contact moved downwardly to an active position, and showing the contacts closed;

Fig. 3 is another elevation similar to that of Fig. 2, but showing the contacts moved downwardly to an extreme inactive position and closed, in order to reveal the available wiping action; and

Fig. 4 is a transverse vertical section through the switch assemblage, taken along the line 4-5 of Fig. 1.

While the invention has been shown and described herein as being especially applicable to electric thermostatic switches which are advantageously applicable to electrically heated fiat irons, it is not my desire to unnecessarily limit the utility of the improvement by virtue of this specific disclosure.

Referring to the drawing, the improved thermostatic switch shown therein by Way of illustration, is adapted to be associated with the wall 6 of various types of heaters, and comprises a supporting bracket 1 having an inverted U-shaped member or flange 8 at one end and an angular abutment projection 9 disposed laterally of the flange 8; an L-shaped rigid upper contact carrier arm l0 pivotally suspended at its medial portion from the flange 8 by means of a pivot pin I I and having one end provided with a downwardly directed flange l2 while its opposite end supports an adjustable but normally fixed contact l3; an L-shaped rigid lower contact carrier arm I4 likewise pivotally suspended at its medial portion from the bracket flange 3 by means of a pivot pin I 5 and having one end provided with an upwardly directed flange It spaced from the flange I2, while its opposite end supports a movable contact I'! which is cooperable with the fixed contact I3 to make and break the electric circuit; an adjusting screw or rod I 8 having screw threads coacting with a flange I9 of the heater wall 6, and being provided at one end with an adjusting wheel while its opposite end 2| coacts with a medial portion of the upper carrier arm Ill; a helical compression spring 22 coacting with the carrier arm flanges I2, IE and constantly urging the upper arm Ill against the rod end and the lower arm I4 toward the abutment projection 9 and toward contact closed position; and a U- shaped thermostatic element 23 disposed between and normally coacting with the fixed bracket projection 9 and with the medial portion of the lower arm I4.

The main supporting bracket 1 with its flange 8 and abutment projection 9 may be formed with the aid of punches and dies, of a single piece of sheet metal or the like, preferably having good heat conducting characteristics, and this bracket I may be detachably attached to the heated wall 6 with the aid of screws 24. The rigid L-shaped contact carrier levers or arms Ill, I l may also be formed of durable metal either by casting, or of sheet metal with the aid of punches and dies, and the pivot pins II, l5 about which the arms II], II are freely swingable, should preferably be removably but firmly attached to the bracket I and flange 8 so as to facilitate assembly and dismantling of the switch mechanism. The adjustable but normally stationary upper contact I3 is secured directly to a sheet-metal conductor plate 25 which is insulated from its carrier arm II] by means of insulation plates 26 and is rigidly attached to the arm IE3 by insulated rivets 21; and the lower movable contact II is likewise secured to a similar conductor plate 26 which is also insulated from its carrier arm I I by mean of insulation plates 29 and is rigidly attached to the arm I4 by insulated rivets 38. Each of the plates 26, 28 is provided with an integral ear to which the flexible leads or conductors BI, 32 may be attached, and it is to be noted that the contact faces of the contacts I3, II are curved so as to provide approximately line contact for every available position of relative adjustment. The upper contact adjusting hand wheel 29 may be provided on its upper face with calibrations or markings which are cooperable with a pointer or the like associated with the heater wall flange I 9, in order to visibly indicate the degree of actual adjustment of the normally fixed upper arm It; and when utilizing the improved thermostatic switch to control the heating of a flat iron, these calibrations of the wheel 28 ordinarily designate the type or class of work to be performed when the wheel is adjusted to various positions.

During normal operation of the improved thermostatic switch, the upper adjustable but normally fixed con-tact carrier arm III should be moved downwardly with the aid of the adjusting hand wheel 20 and rod IE, to a position such as shown in Fig. 2', so that the lower arm I4 will not engage the abutment projection 9 of the supporting bracket I when the contacts I3, H are closed. The U-sh'aped thermostatic element 23 which coacts with the projection 9 and lower arm I4 and which is retained in proper place by the bracket flange 8, will be in relatively collapsed condition as shown in Fig. 2 when cool, and will then permit the contacts I3, I I to engage each other thus completing the circuit and energizing the electric heater which the switch controls. The coil spring 22 which coacts with the end flanges I2, I6 of the carrier arms Ill, I4 will keep the contacts I 3, I! closed, until sufiicient heat is imparted to the thermostatic element 23 to expand the latter and cause it to operate in opposition to the spring tension so as to swing the lower arm I4 downwardly and to thereby separate or open the contacts I3, I! thus breaking the circuit. This action is normally quite rapid; and When the thermostatic element 23 again cools off, the spring 22 will become quickly eflective to again close the contacts I3, I? and to make the electric circuit. The degree of heatin and cooling of the element 23, necessary to effect such automatic opening and closing of the switch, may obviously be readily varied by merely manipulating the hand wheel 20, and the screw threads on the rod I3 may be made relatively small or fine in order to augment the sensitiveness of the adjustment. As indicated by Figs. 1 to 3 inclusive, the line of engagement between the curved contacts I 3, I I, will be shifted slightly for each successive adjustment of the upper carrier arm Ill; and due to the use ofseparate parallel pivot pins II, I5 for swingably supporting the contact carrier arms Ill, I4, the free swinging movement of these arms is not materially retarded by their mountings and considerable lateral wiping action is imparted to the contacts l3, I'I regardless of the position of adjustment. Repeated adjustment and operation will therefore maintain the faces of the contacts I3, I 7 clean at all times, thus assurin most effective contacting and insuring dependable operation; and while the positions of the elements shown in Figs. 1 and 3 are abnormal or inactive positions, the mechanism may be adjusted to various intermediate active positions throughout a considerable range.

From the foregoing detailed description, it will be apparent that my present invention provides an improved thermostatic switch assemblage which is simple, compact and durable in construction, and which is moreover highly reliable in operation and flexible in its adaptations or uses. The improved structure is especially adapted for use in conjunction with portable devices such as fiat irons, and jarring or jolting of the mechanism does not impair or detrimentally affect its normal operation. The actuation of the improved thermostatic switch may obviously be varied throughout a considerable range by merely adjusting the hand wheel 26 and rod I8, and by forming the contacts I3, Il with oppositely curved faces, and by mounting the contact carrier arms on separate pivots, the contact faces are maintained clean and most eflective for all positions of relative adjustment. The U-shaped thermostatic element 23 and the compression spring 22 cooperate to insure eifective actuation of the switch at all times, and the various parts of the assemblage may obviously be constructed of suitable materials and with the aid of punches and dies in a durable manner. All portions of the improved switch are readily accessible and the normal operation thereof is automatic, and the improved thermostatic switch has proven highly satisfactory in actual use and can obviously be manufactured at moderate cost. The improved construction of the supporting brackets 1 also permits the various parts to be readily assembled and dismantled, while providing a firm support and retainer for the contact carrier arms l0, H, the thermostatic element 23, and the spring 22 when properly assembled.

It should be understood that it is not desired to limit this invention to the exact details of construction or to the precise mode of operation, herein shown and described, fo various modifications within the scope of the claims may occur to persons skilled in the art.

I claim:

1. A switch comprising, a pair of elongated rigid L-shaped carrier arms swingable about spaced pivots and having their corresponding ends provided with surfaces which are spaced apart and disposed on one side of said pivots, cooperating contacts carried by the opposite corresponding ends of said arms, a compression spring coacting with said surfaces and con tantly resiliently urging said contacts toward each other through said rigid arms, and a U-shaped thermostatic element interposed between said arms on the opposite side of said pivots and acting in opposition to said spring.

2. A switch comprising, a pair of elongated rigid L-shaped carrier arms swingable about spaced pivots and having their corresponding ends directed toward each other and provided with surfaces which are spaced apart and disposed on one side of said pivots, cooperating contacts carried by the opposite corresponding ends of said arms, a compression spring coacting with said surfaces and constantly resiliently urging said contacts toward each other through said rigid arms, a U-shaped thermostatic element interposed between said arms on the opposiite side of said pivots and acting in opposition to said spring, and adjustable means for varying the fixed positioning of one of said arms.

3. A switch comprising, a supportiing bracket having an integral flange and an integral fixed abutment spaced from said flange, parallel pivots secured to said bracket and said flange, a pair of carrier arms freely swingably suspended from said pivots and extending on opposite sides of said abutment and having cooperating contacts at the corresponding swinging ends thereof, resilient means coacting directly with the opposite corresponding ends of said arms for constantly urging said contacts toward each other, and a U-shaped thermostatic element disposed between said arms and coacting with said fixed bracket abutment and with one of said arms for moving said contacts apart.

4. In a switch, a supporting bracket having spaced parallel pivots and a fixed abutment projecting from the same side thereof, a pair of approximately parallel elongated contact carrier arms swingable upon said pivots and extending on opposiite sides of said abutment, each of said arms having an end flange extending toward the other arm in spaced relation to each other, a spring coacting with said flanges for constantly urging the contact carrying end of said arms toward each other, and a thermostatic element for separating said arm ends interposed between said fixed bracket abutment and one of said arms.

5. In a switch, a supporting bracket having spaced parallel pivots and a fixed abutment projecting from the same side thereof, a pair of rigid approximately parallel elongated contact carrier arms swingable upon said pivots and extending on opposite sides of said abutment, each of said arms being of L-shape and having an end flange extending toward the other arm in spaced relation to each other, a spring coacting with said flanges for constantly urging the contact carrying ends of said arms toward each other, a thermostatic element for separating said arm ends interposed between said fixed bracket abutment and one of said arms, and adjustable means coacting with the other arm to swing the same about its supporting pivot.

6. In a switch, a supporting bracket having spaced parallel pivots and a fixed abutment projecting from the same side thereof, a pair of rigid approximately parallel elongated contact carrier arms swingable upon said pivots and extending on opposite sides of said abutment, each of said arms being of L-shape and having an integral rigid end flange extending toward the other arm in spaced relation to each other, a helical compression spring coacting with said flanges to :eparate the contact carrying ends of said arms, and a U-shaped thermostatic element for separating said arm ends interposed between said fixed bracket abutment and the medial portion of one of said rigid arms.

7. In a switch, a supporting bracket having spaced parallel pivots and an integral fixed abutment projecting from the same side thereof, a pair of approximately parallel elongated rigid contact carrier arms swingable upon said pivots and extending on opposite sides of said abutment, each of said arms being of L-shape and having an integral rigid end flange extending toward the other arm in spaced relation to each other, a helical compression spring coacting with said flanges midway between said pivots to separate the contact carrying ends of said arms, a U-shaped thermostatic element for separating said arm ends interposed between said fixed bracket abutment and the medial portion of one of said arms, and a threaded rod coacting with the corresponding medial portion of the other of said arms for moving said arm toward said abutment to compress said element.

8. In a switch, a bracket having parallel pivots and a fixed abutment projecting from the same side thereof, a pair of elongated arms freely swingably suspended upon said pivots and extending along said side of said bracket, coacting contacts carried by the corresponding swinging ends of said arms beyond said abutment, the coacting surfaces of said contacts being reversely curved and being relatively shiftable during swinging of said arms, a spring coacting with the opposite ends of said arms for constantly urging said contacts toward each other, and a thermostatic element interposed between said fixed abutment and one of said arms for separating said contacts.

9. In a switch, a bracket having parallel pivots and a fixed abutment projecting from the same side thereof, a pair of elongated arms freely swingably suspended upon said pivots and extending along said side of said bracket, coacting contacts carried by the corresponding swinging ends of said arms beyond said abutment, a spring coacting with the opposite ends of said arm for constantly urging said contacts toward each other, and a thermostatic element interposed between said fixed abutment and one of said arms for separating said contacts.

10. In a thermostatic switch, a bracket having thereon a pivot and a fixed abutment spaced from the pivot, an elongated arm freely swingably suspended upon said pivot, another arm swingably suspended from said bracket adjacent to said pivat and extending in the same general direction as said first mentioned arm, coacting contacts carried by the corresponding swinging ends of said arms, a spring coacting with said arms to constantly urge said contacts toward each other, a thermostatic element interposed between said fixed abutment and one of said arms, and adjustable means coacting with the other arm to properly relatively position said contacts for actuation by said thermostatic element.

11. In a thermostatic switch, a bracket having thereon a pivot and a fixed abutment spaced from the pivot, an elongated arm freely swingably sus-

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