US1655480A - Electric heater - Google Patents

Description

Jan. 10, 1928. 1,655,48@

R. L. UHL

ELECTRIC HEATER Filed Jan. 5, 1923 Figi.

2 Sheets-Sheet l Jan. 1o, 192s. 1,655,48

R. L. UHL

ELECTRIC HEATER Fil'ed Jan. s, 1923 2 Sheets-Sheet 2 Pig.

lll 11111/1111. 'Il

Inventor: Robe'rt L.UI'1|J His Attorvwe.

Patented Jan. 10, 1928.

UNITED sTATEs PATENT oEFICE.

ROBERT L. UBL, OF ONTARIO, CALIFORNIA', ASSIGNOR TO EDISON ELECTRIC APPLI- ANCE COMPANY, INC., OF CHICAGO, ILLINOIS, A CORPORATION OF NEW YORK.

ELECTRIC HEATER.

Application med January 3, 1923. Serial No. 610,510.

My invention relates to electric heaters, particularly to means for protecting electric heaters from over heating, and has for its object the provision of improved means of thls character.

My improved arrangement is particularly applicable to electrica ly heated fiat irons, although obviously it is not limited to this application.

- More specifically my invention relates to protective devices in which a fusible material, commonly a metal or alloy of metals, is employed. This fusible metal is ordinarily subject to oxidation upon repeated melting and solidifying, whereby its characteristics, and hence the characteristics of f the protective device, may be changed. I-Ieretofore attempts have been made with more or less success to produce a fusible metal which does not have this tendency to oxidize.

In carrying out my invention, I provide means for preventing oxidation of the metal whereby I may use any suitable fusible alloy without regard to its tendency t0 oxidize. In accordance with my invention, I enclose the fusible metal in a sealed container whereby it is protected from Contact with the air and oxidation thus prevented. In one form of my invention I provide a holding member for the switching mechanism, which member extends into the container and has its inner end anchored in the fusible metal, the container being adapted to flex to permit movement of the holding member to release the switching mechanism upon the fusible metal. I have also provided reset means whereby the holding member is returned to its normal position after the release of the switching mechanism.

For a better understanding of my invention, reference should be had to the accompanying drawings in which Fig. 1 is a view partially in section of an electric flat-iron provided with protective means embodying my invention; Fig. 2 is a plan View of Fig. 1 with the cover of the iiat iron removed showing the switching mechanism in open position; Fig. 3 is an enlarged plan view of the switching mechanism showing the switch in closed osition; Figs. 4 and 5 are views showing etails of the switching mechanism; Fig. 6 is an enlarged sectional view of the fusible control device; Fig. 7 is a sectional view along the line 7-7 of Fig. 6;

the switching mechanism in closed position.

while Fig. 8 is a fragmentary plan view showing a modified form of my invention.

. Referring to Figs. 1 and 2 of the drawing, I have shown my invention in one form 1n connectlon with a well known form of flat iron comprising a sole plate 1() and a pressure plate 11. The heating element for the flat iron is held between the pressure plate and sole plate, the plates being secured together by means of screw 13. In the sole plate I provide a circular recess 14 in which is secured a sealed rece tacle 15 containing a fusible metal 16. he container 15 is made of a suitable material such as steel, and has its inner surface oxidized or otherwise treated or protected to prevent amalgamation with the fusible metal at high temperature, such as when the fusible metal is in a molten condition. Extending upward from the receptacle 15 through an opening 17 in the pressure plate is a stem or holding member 18 which cooperates at its upper end with suitable switching mechanism 19 mounted on top of the pressure plate. The lower end of the stern 18 extends into casing 15 and is embedded in the fusible metal whereby the stem 18 is normally secured in an upright position by the fusible alloy. When so secured the stem is adapted to hold Upon the occurrence of excessive temperatures fusing the alloy, the stem is released and is tilted to permit the switching mechanism to open the heating circuit.

'Ihe particular switching mechanism shown forms a part of a copending application of Earl I I. Richardson, Serial No. 446,618, filed February 21, 1921, assigned to the same assignee as this invention. It comprises a supporting plate 20 (Fig. 3) upon which is gg, secured a bracket 21 provided with oppositely extending wings 22 and 23, which are parallel with plate 2O and spaced therefrom. Pivotally mounted on plate 2O is a switch member 24 carrying contacts 25 and 26. The in@ switch member is provided with two parallel laterally extending arms 27 and 28, arm 28 being bent at right angles and provided at its end with'knife edge lateral projecttions 29 and 29 (Fig. 5) which are pvoted ma respectively in suitable apertures in wing 23 and plate 20. The switch member 24 is operated on its pivots with a quick snap action from open to closed position and vice versa by means of a relatively strong coiled n@ spring 30, one end of which is secured to plate 20, while the other end 31 extends` parallel with plate 20 to a po int adjacent pivots29 and 29' where 1t 1s connected through link s2, yoke se and link 3i to the H adapted to engage with a projection 36 on the left hand end of a lever 37. Lateral projections 31 are provided on the upper end of the latching member 35 which projections are held seated on the hooks 40 on the forked end of a switch operating arm 41 by the tension exertedby spring 30, the latching member lying between the prongs on the end of an operating arm 41, whereby the latching member is pivot-ally mounted on theend of arm 41. An aperture 42 is provided in arm 41 through which the lower end of latch 35 is forced by the action of spring 30 for engagement with projection 36 on lever 37. The operating arm 41 is shaped so as to extend below bracket 21 and is pivotally supported at its left hand end by means of lateral knife edge projections 43 and 44 thereon (Fig. 5) cooperating with apertures in wing 22 and plate 20- respectively. The end of arm 28 adjacent its pivots 29 and 29 is forked so as to provide two prongs between which links 32I and 34 move. Suitable slots are provided for link 32 in link 34 and arm 41. A stop l45 on plate 20 limits the movement of arm 41 under the influence of spring 30.

The lever 37 is centrally pivoted on plate 20 in parallel relation therewith and is biased in a clockwise direction by a comparatively weak spiral reset spring 46 having one end secured to plate 20 and the other end secured to lever 37 between projection 36 and the pivot of the lever. The upper end of stem 18 is reduced in size and extends through an aperture 47 in the right hand end of lever 37. A projection 49 is provided on plate 20 forming a stop against which stem 18 comes to rest under the iniiuence of reset spring 46.

The movable contacts 25 and 26 are adapted to cooperate with stationary' contacts 50 and 51 in the heating circuit secured to plate 20 in insulated relation therewith. As shown, theinovable contacts 25 and 26 are mounted onthe ends of -an electrically con, ducting bridging member 52 which is secured in insulated relation to, the switch member 24 and through which the heating circuit is closed when the movable contacts engage the stationary contacts. Preferabl the member 52 is loosel secured to switc member 24 to allow sel adjustment of the contacts when the switch is closed. A but ton 53 is pivotally secured to operating arm 41. This button extends through the dat keeaaeo iron casing and .by pressing it inward the switch may be closed.

Referring to Figs. 6 and 7 in one form of my invention the c lindrical container 15 for the fusible meta 16 .is provided with a cover 55 which is in the form of a flexible diaphragm made of a suitable material, such as manganese nickel. The container 15 has a anged top upon which the cover or diaphragm 55 rests, a clamping ring 56 being placed on the diaphragm. The clamping ring and the cover are secured to 'the container and the container then sealed by means of a brazed or welded joint 57. The stem 18 is carried by the diaphragm. lt extends centrally through the diaphragm 55 and is tightly secured to the diaphragm in this central position by means of a brazed or welded joint 58. It will be observed that the container 15 is thus hermetically sealed so that it is impossible for air to come in contact with the fusible metal 16. Oxidation of the fusible metal is thus prevented. In sealing the container a small amount of air may be entrapped with the fusible metal, but the oxidation resulting from this entrapped air is negligible. The diaphragm 55 is adapted to flex, to permit lateral moreq ment of the upper end of stem 18 and acts in elfect as a ivot for the stem.

. Special anc orin means may be provided, as shown, for the ower end of the stem 18. On the lower end of the stem is'a U-shaped metallic anchor member 59 provided with slots so as to form a plurality of downwardly extending projections 60 and 61 on the sides, four being shown on each side. These projections extend into the fusible metal 16. The anchor member 59 straddles a transverse anchor member 62 secured to the container 15, for example, by providing recesses' 63 and 64 in its ,ends and depressing the wall of the container into these recesses. ln the member 62 are a plurality of aperture 65, three being shown. The diaphragm 55 is protected from contact with the fusible metal by means of a disc 66 secured to stem 18 adjoining anchor 59 and a washer 67 in lUU engagement therewith fitting in the top of imica, and are provided to prevent the fusible metal from coming in contact with the diaphragm.` Without this precaution there is dan er of the metal amalgamating with the diap ragm at high temperatures. i

A recess 68 is provided in the sole plate 10 with which an emboss on the container 15 is adapted to register. The angular position of the container with relation to the sole plate is thus definitely fixed, this position eing such that the anchor member 62 extends in a direction substantially parallel with the direction of the right hand end of iso lever 37. The container 15 is secured by a clamping washer 69 which is Hush with the sole plate 10.

As thus constructed and arranged, the operation of my invention is as follows: Assuming the switching mechanism tobe 1n closed position, as shown in Fig. 3, stem 18 bei-ng secured in an upright position by the fusible alloy and holding lever 37 agalnst turning, upon the occurrence of a predetermined maximum temperature in the fiat iron, the fusible metal 16 will melt and release anchor member 59 and hence stem 18. Lever 37 is then rotated through a small angle in a counter-clockwise direction by spring against the pull of reset spring 46 so that latch slips oif projection 36 of lever 37, releasing arm 41, whereupon the switch member 24 is moved to open position, operating arm 41 coming to rest against stop 45, as shown in Fig. 2. After the release of arm 41, it will be observed that the switch member 24 will not be moved until the link 34 has been moved past pivots 29 and 29. When this takes place the switch member will be thrown to open osition with a quick snap action opening the eating circuit. Immediately after releasing latch 35, lever 37 is moved by spring 46 in a clockwise direction back to its former upright position, the upper end of stem 18 coming to rest against stop 49. Upon the solidification of the alloy as the flat-iron cools the stem will therefore be again secured in an upright position ready to hold the switch closed. 'Upon pressing button 53 to close the switch it will be observed that switch member 24 will not be moved until link 34 has been moved back past pivots 29 and 29 when the switch member will be moved to closed position with a snap action.

It will be observed that stem 18 upon the release of anchor 59 acts as a lever having for its pivot its point of support in the flexible diaphragm 55, the diaphragm flexing to permit rocking movement of the stem on this pivot and disc 66 slipping freely with relation to washer 67. The direct-ion of movement of anchor 59 is parallel with the length of the stationary anchor member 62. By reason of the projections 60 and 61, anchor 59 has a tendency to carry the fusible metal 16 with it during this movement. The eEect of thek stationary anchor 62 is to prevent displacement of the fusible metal, the fusible metal being anchored in apertures 65. As a result of this cooperation between the anchors 59 and 62, a shearing action is exerted on the fusible metal instead of simply a displacement action. Anchor 59 is thus effectively secured until released by the melting of the fusible metal, creeping of the anchor being prevented. The stationary anchor member 62 also prevents lost motion due to looseness caused by shrinkage of the fusible material in the container for while the fusible metal shrinks away from the container, in solidifying, at the same time it tightly grips the anchor 62 so as to be held immovable 1n the casing. It will be observed that the fusible metal'is divided into two portions by the anchor 62 which portions are connected through the holes 65 in the anchor. The shrinkage of the fusible metal thus tends to tighten it onthe anchor 62 whereby looseness in the container is prevented.

Any suitable fusible metal may be used, although I preferably use one having a quick break down or sudden change from a solid to a liquid. Such a fusible metal is disclosed in the aforesaid copending application of Earl H. Richardson.

In Fig. 8 is shown a modified form of my invention in which the reset spring 46 is dispensed with, spring 30 serving both to open the switch and reset the stem 18. A reset arm is provided on the operating arm 41, this arm being bent laterally around lever 37 and having at its end a projection 71 which as the operating arm 41 moves toward open position, engages a projection 72 on the right hand end of lever 37 returning the lever back to its original position and resetting stem 18.

While I have described my invention as embodied in concrete form and as operating in a specific manner in accordance with the provisions of the patent statutes, it should be understood that I do not limit my invention thereto, since various modifications thereof will suggest themselves to those skilled in the art without departing from the spirit of my invention', the scope of which is set forth in the annexed claims.

What l claim as new and desire to secure by Letters Patent of the United States, is z- 1. A. temperature cut-out for electric heaters comprising switching means therefor, temperature'responsive means for holding said switching means in closed position comprising a fusible material, and an hermetically sealed container for said fusible material, said switching means being outside of said container.

2. A temperature cut-out for electric heaters comprising control means for said heater biased to one position, a fusible material for holding said control means in another position, and a closed container for said fusible material, said container being arranged to -flex upon the release of said control means.

3. A temperature cut-out for electric heaters comprising switching means therefor biased to open position, temperature responsive means for holding said switching means in closed position comprising a fusible material, and an hermetically sealed container for said fusible material having a portion flexing upon the release of said switching means.

for biased to one position, a closed container, a fusible material in said container, and means secured by .said fusible materlal for holding said swltchlng means 1n another position, said container being arranged to flex to permit movement of said holding means to release said switch upon the fusing of said material.

5. A temperature vcut-out for electric heaters comprising switching means therefor biased to open position, means for holding said switching means in closed position, a fusible metal for normally securing said holding means but releasing it to eect the opening of said switching means upon the occurrence of a predetermined temperature, a sealed container for said fusible metal, and a rigid connection between said container and said holding means, said container Hexing upon movement of said holding means.

6. A temperature cut-out for electric heaters comprising switching means therefor f biased to open position, a sealed container,

a flexible diaphragm forming a wall of said container, a fusible metal in said container, and means secured by said fusible metal extending through and rigidly secured to said diaphragm for holding said switching means in closed circuit position but released by said fusible metal upon the occurrence of a predetermined temperature, said holding means being permitted to move through the flexing of said diaphragm to effect the release of said switching means.

7 A temperature cut-out for 'electric heaters comprising switching means therefor biased to open position, means for holding said switching means in closed position comprising a pivoted member, a fusible metal normally securing said 'pivoted member but releasing it to effect the opening of said switching means upon the occurrence of a predetermined temperature, and a sealed container lfor said fusible metal one of the walls of which forms the pivot of said memvaesasao releasing it to eect the opening of said swltching means upon the occurrence of a predetermined temperature, a sealed container for said fusible metal, and a exible diaphragm forming one of the wallsof said container, said member extending through said diaphragm so as to be pivoted thereon.

9. A temperature cut-out for electric heaters comprising switching means therefor biased to open position, means for holding said switching means in closed'position, a fusible metal normally securing said holding means but releasing it to eect the release of said switching means upon the occurrence of a predetermined temperature, a flexible sealed container for said fusible metal to which said holding means is rigidly secured, said container fiexing upon movement of said holding means, and means for returning said holding means to normal position after the release of said switching means.

l0. A temperature cut-out for electric heaters comprising switching means therefor biased to open position, means for holding said switching means in closed position comprising a pivoted member, a fusible metal normally securing said ivoted member but releasing it to effect t e opening of said switching means upon the occurrence of a predetermined temperature, a sealed container for said fusible metal, a iexible diaphragm forming one of the walls of said container, said member extending through said diaphragm so as to be pivoted thereon, and resilient means for returning said member to normal position after the release of said switching means.

11. A temperature cut-out for electric heaters comprising Aswitching means therefor biased to open position, a fusible metal, a lever forming a latch for said switching means, a pivoted member having one end cooperating with said lever and its other end normally Secured by said fusible metal but released to eEect the opening of said switching means upon the occurrence 'of a predetermined temperature, a sealed container for said fusible metal and a flexible diaphragm forming a walll of said container and acting as the pivot for said member.

ln witness whereof, I have hereunto set my hand this 27th day of December, 1922.

RGBERT L. UHL.

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