US1996157A - Electric sadiron - Google Patents

Description

April 2,-1935. x. JEPPssoN ELECTRIC SADIRON FiledJuly 1, 1932 3 Sheets-Sheet l zh y ad;

April 2, 1935. JEPPssoN ELECTRIC SADIRON Filed July 1, 1952 5 Sheets-Sheet 2 I. JEPPSSON ELECTRIC SADIHON Filed July 1, 1932 April 2,1935.

3 Sheets-Sheet 3 Jaden/r:

Patented Apr. 2, 1935 UNITED STATES PATENT OFFICE ELECTRIC sADmoN Ivar Jeppsson, Chicago, Ill., assignor to Chicago Flexible Shaft Company, Chicago, Ill., a corporation of Illinois Application July 1, 1932, Serial N0. 620,375

10`Claims. (Cl.219-25) This invention relates to sadirons and more parlight service or drop below this range when used ticularly to electric sadirons having improved on heavy service. Thus,inordertokeep the ironthermostatic means for controlling the temperaing surface sufficiently warm when used on heavy ture thereof and ymaintaining a uniform ironing damp materials it was necessary by the methods temperature. of the past to heat the interior of the iron to a 5 While thermostatic means for controlling the very much higher temperature in order to give temperature of irons are well known, none of a sufllciently high rate of heat iiow from the inthem operate satisfactorily on a wide variety of terior of the iron to the ironing surface. This work, 'Ihe principal sources of the diiiiculty are meant that the shut off temperature of the thertwo-fold, those troubles dealing purely with memostat must be very high since it is located within 10 chanical diiiculties which result in total or parthe iron. On the other hand, if the thermostat tial loss of function such as breakage, warpage, was set to take care of this condition, when the high cost of construction, etc., and those resultiron was used on light surface this high rate of ingfrom improper design due to a failure of the heat ow and this high temperature of the center inventor to fully comprehend and coordinate the of the iron would cause the ironing surface to 15 various features involved. The first class of reach a dangerously high temperature. At the troubles are due largely to the use of complicated outset, therefore, no method was apparent for mechanisms which have heretofore been considysolving this diiculty, and the solution of this ered necessary to bring about the automatic problem forms a part of the present invention.

regulation of the iron. These parts must operate In connection with the solution of this problem it 20 under relatively high temperatures and, as a rebecame essential to materially simplify and imsult, parts such as springs have been prone to prove the thermostatic mechanism, which imiail after the iron has been in use a short period provement forms another phase of the present in- 01' time and likewise the eIlCeDCY 0f Other Darts, vention. By the present inventionIhave substansuch as bearings, have been impaired by corrosion tially eliminated the second class of troubles de- 25 Which attends the use 0f high temperatures and scribed above and have materially reduced those the presence of steam during the ironing operaof the nrst class by reducing the number and tions. The second class of troubles have resulted changing the character and location of the parts largely from failure of the maker to properly coof the thermostatic control.

Ordinate and arrange the functions. 'I'he result A primary object of the invention is the provi- 30 l5 that the iI'OIl may Operate satisfactorily 011 light sion of an improved sadiron construction wherein work but when used for heavier work heat is so the thermostatic mechanism is quickly responsive rapidly drained from the TOD that the OperatOr to temperature changes of the sole plate surfaces. must stop ironing at relatively short intervals to I have also aimed to reduce the cost of manu- Permit the ilOnnS Surface 0f the S016 plate t0 I'efacture and the possibility of faulty operation of 35 gein its temperature. the thermostatic control mechanism by simplify- Irons of high wattage were used in an attempt ing the construction, reducing the number of to overcome the latter trouble and provide sufparts and the amount of insulation required, cient heat to the sole plate to maintain the Another Object of the invention is to provide o,

ironing surface at operating temperature under construction which facilitates the assembling of 40 severe conditions. While this was possibly of some the iron and the adjusting of temperature Control assistance the difficulty still remained. It was mechanism ound-tha2t under heavy duty suchfor example A further object is to provide improved manual as in ironing damp, heavy tablecloths, the ther- Contr 01 mechanismy 4 esternazioni e@ I r ironing surface was far below that required, thus, means for protectmg the u lelmosfhfrqm bem when the heat supplied by the heating element halted by the .preg s 1.11? Welg t o e mm an was needed the most, the thermostat shut oi the to Improve lts Sensltlvlty b3. reducmg the sla 'current instead of permitting its continued flow )Ccupled by the thermostatl? elment by brmg' 50 as desired. It was thus a major problem to so armg the element 0105er t0 the lfomng surface and range the mechanism and iron that the sole plate by Constructing the S019 plate 0f a material would be maintained within the ironing range at through which the heat iS rapidly CDIldl-letedall times, and so that the temperature would not Other objects and attendant advntges Will rise above this range when the iron was used in become apparent to those skilled in the art from 55` the following description and the accompanying drawings, in which- Figure 1 is a vertical section taken longitudinally through the iron;

Fig. 2 is a section on the line 2--2 of Figure 1;v

Fig. 3 is a top perspective of the heating element and connected parts;

` Fig. 4 is a section on the line l-- of Figure l; Fig. 5 is a section on the line 5 5 of Figure 1; Fig. 6 is a top view of my improved pressure weight, and

Fig. 7 is a section on the line 7--7 of Fig. 6. I have found that one of the major difficulties in thermostatically maintaining a uniform ironingsurface at the sole plate of the iron lies in the slow rate at which the heat'iiows from the interior of the iron to the surface of the iron.

As a result of this, when the heat is rapidly drained from the sole plate it is necessary for the interior of the iron to attain excessive temperatures in order to supply the heat to the sole plate at a sufficiently rapid rate of speed. If lthe thermostat is set to maintain the interior of the iron at this temperature the ironing surface will be overheated when used in light service. The solution of these difficulties has, broadly speaking, involved two types of improvements. One of these improvements is the manufacture of the sole plate of a material which will conduct the heat very rapidly so that the heat of the sole plate and the heat supplied by the heating element will be conducted to the ironing surface at a. much more rapid rate of speed than heretofore whereby it becomes unnecessary to maintain such a wide differential in temperature between the interior of the iron and the ironing surface. To this end, I have made the sole plate of a light aluminum alloy. I have found that aluminum alone may be used but better results will be had from the aluminum alloy because of its greater hardness, strength and higher melting point. If metallic aluminum alone is used there is a danger of the metal melting should the temperature overrun or become excessive. This alloy should have a higher melting point than aluminum and should be such as to have a high coefficient-,lof thermal conductivity, one suitable alloy duralumin, This metal has a specific heat conductivity of about four to five times that of iron and consequently transmits the heat from the pressure weight and from the heating element at a much more rapid rate of speed whereby the temperature differential between the interior of the iron and the ironing surface may be greatly decreased and at the same time permit the ironing surface to be maintained at a substantially uniform ironing temperature during heavy service. This object is materially facilitated by reducing the weight and thickness of the pressure weight so as to reduce in as far as is practically possible, the heat capacity thereof. As a further result of this reduction in Weight and thickness the efiiciency of the iron is also improved since I have found that the convection of heat from the cover is materially less. For example, with my improved construction I have found that the temperature of the air at a point Ajust above the cover, is materially lower than with irons of conventional construction.

According to another phase of the invention the thermostatic element is so arranged and positioned as to be very accurately responsive to temperature changes of the ironing surface ofthe sole plate, so that regardless of the temperature of the interior of the iron the current Supply t0 the heating element will not be cut oil unless the ironing surface raises above a predetermined temperature.

Referring first to Figure l-the iron is provided with the conventional sole plate designated generally by the numeral 1, pressure weight S, cover 9, handle strap il, and handle l2. The sole plate, which is preferably made of an aluminum alloy as above described, is provided with a longitudinal slot in its upper surface forming a thermostat well i3 and with threaded openings for the reception of screws ill which serve to hold the pressure weight against the sole plate, a heating element I5 beingy interposed therebetween. The principal purpose of the pressure weight is to hold the heating element firmly against the sole plate and prevent warping of the former. The cover 9 and handle strap lt are secured to the pressure weight by means of a pair of screws i6 which pass into threaded openings li in the pressure weight. The cover is provided at the rear with a heel rest designated generally by the numeral It which is shaped to provide an angular portion I9 directly at the rear of the cover and just above the level of the sole plate, a plug guide 2l surrounding the terminals 22 and 23, presently to be more fully described, and an ear 2t, the angular portion i9 and ear 2Q serving as rests upon which the iron may be rested when not in service. The plug guide portion 2l is connected to the cover by downwardly depending fingers 25. The cover is also provided with an opening 26 at the rear end thereof substantially midway between its side walls for the passage of a strip spring 2l which is secured in the angular portion i9 of the heel rest by means of a rivet 2t and passes into the interior of the cover through the opening 2t, to support contact points presently to be more fully described.

The pressure weight 8 is cast with a plane loweui` surface and the body thereof is only of sufficient thickness to exert a uniform pressure on the top of the heating element Aand prevent warpage thereof. To lend rigidity to the pressure vsure weight and prevent its distortion under high heat I have provided a.. plurality of ribs sa on the upper surface. An upwardly extending boss l0 is formed in the center of the pressure weight to receive the bolts It and i6 and is provided with fingers Ita for contact with the cover` 9. Likewise,bosses 20 serve to receive bolts lil at the rear of the iron.

The results obtained from the use of the improved pressure weight are three-fold-flrst, the iron being a slower conductor of heat than the duralumin sole plate, the heat from the heating element is pulled through the sole plate more rapidly than it is conducted to the pressure weight and there is therefore less heat conducted to the pressure weight during the ironing operations. Secondly, the pressure weight results in an iron of lesser total weight; and thirdly, -the less heat is lost to the air whereby the eilciency of the iron is increased as demonstrated by the fact that the temperature at a point between the cover and handles about where the knuckles of the operator lie, is about 30 F., lower than is the case with a conventional iron.

In Fig. 3, I have shown the heating element l5 l sufllcientheat for any purpose to which the iron is adapted. 1000 watts capacity being generally sufficient. 'Ihe upper plate 3i is bent downwardk at its edges, as shown at 33, so that it may be crimped against the lower plate to hold the two plates and the interposed heating unit together. Eyelets 34 pass through the plates 29 and 3l and the insulation and serve to hold the plates together and also to provide openings through the heating element for the passage of the screws I4. A rectangular opening 35 is formed in the plates 29 and 3i and inthe insulation which is necessarily provided to insulate the heating unit from the plates, the opening thus passing completely through the heating element. The purpose of this opening will presently become apparent. The terminals 22 and 23 arel attached to a supporting plate 36, which, in the assembled iron, is supported on the pressure weight by the screws I4 in the manner shown in Fig. 4, the supporting plate thus flxedly holding the terminals against the forces normally applied thereto through the customary drop cord plug which fits over the terminals. The terminal 23 is connected to one side of the heating unit 32 by means of a lead 31 held between the plates 29 and 3| while the terminal 22 is connected to a contact point 39 by means of a lead 39, the lead being secured between the plates of the heating element and the contact point 39 projecting upward through the upper plate 3l and being insulated therefrom. The opposite end of the heating unit 32 is connected to a contact point 4i which projects upward through the plate 3| and is insulated from this plate, the contact points 38 and 4I being positioned on opposite sides of the opening 35. Thus, by establishing a. connection between the contact points 38 and 4I the electric current supplied to the terminals 22 and 23 will pass from the terminal 23 through the lead 31, the heating unit 32, the contact point 4 I, the contact point 38, the lead 39 to the terminal 22. Referring to Figures l and 4, the heating element circuit is completed by a switch member supported on the inner end of the spring 21. This consists of a crossbar 42 fixed to the end of the spring 21 within the cover and directly above the Contact points 38 and 4I by means of a rivet 43, the spring and rivet being insulated from the crossbar by means of insulation pieces 44, 45, 46 and 41. Contact points 48 and 49 are secured to the ends of the crossbar 42 in a position to register with the contact points 38 and 4i, respectively. The electric circuit of the heating element between the contact points 38 and 4i thus being completed through the contact point 48, the crossbar 42 and the contact point 49. The movable switch element being supported on the free end of the spring 21 is normally urged into a closed position with the opposed contact points in contact by the spring but is capable of movement against the tension of the spring to separate the contact points and open the heating element circuit. Through this means the operation of the heating element and thus the heat supplied tothe iron is regulated by movement of the movable switch member opening and closing the circuit therethrough.

Opening and closing of the switch is automatically controlled through thermal-responsive mechanism shown best in Figure l. This consists of a bimetallic element designated generally by 5I positioned longitudinally in the slot i3 of the sole plate so that the element is horizontal transversely of its length. A pin 52 is secured to the bi-metallic element near one end and projects beyond the edges of the element to provide trunnions which are received in spaced ears 53 on the lower surface of the heating element. These ears may be. advantageously formed by merely striking out a portion vof the lower plate 29 of the heating element. This construction permits the bimetallic element to rotate vertically about the pin 52. A finger 54 is secured to the bimetallic element adjacent to the opposite end thereof and projects upwardly in a position such that by rotation of the bimetallic element it will pass through the opening 35 and come into contact with the head of the rivet 43 and lift the contact points 48 and 49 free of the contact points 39 and 4i, thus breaking the circuit through the heating element. The temperature control mechanism is provided with means acting against the end of the bimetallic element near the pin 52 for holding the bimetallic element in a position such that warpage thereof due to changes in temperature will cause the finger 54 to open and close the circuit at predetermined temperatures. This consists of a cylindrical member 55 passing through the heating element and secured to the lower plate 29 thereof by riveting or otherwise. as shown at 56. The inner surface of the cylindrical member 55 is provided with threads 55 to receive an externally threaded shaft 51. The threads 58 of the shaft 51 cooperate with the threads of the member 55 in such a manner that rotation of the shaft 51 will cause its vertical movement within the cylindrical member. A peripheral slot 59 at the upper end of the member 55, best shown in Fig. 3, extends only a portion of the distance around the member 55 and serves to receive a pin 6I projecting from the surface of the shaft 51 to limit the rotation of this shaft by contact of the pin against the shoulders or ends of the slot. The rotation of the shaft 51 is thus limited to about a half turn although, obviously, this may be made to fit the circumstances. A rod 62 is axially positioned within the shaft 51 and is arranged to project from the lower end thereof for contact against the rod of the bimetallic element 5i, the rod serving to hold this element in the desired rotative position. The rod 62 is provided with a threaded portion 63 having threaded engagement with the inner surface of the shaft 51 and is provided with a slot 54, or other device, to permit manual rotation of the pin 62 with respect to the shaft. Through this means the longitudinal position of the pin in the shaft may be varied as desired. A threaded cap 65 is threaded into the opening at the upper end of the shaft 51 and is screwed down against a ball 65 which bears against theupper end of the pin 62, the cap 65 and ball 66 preventing rotation of the pin with respect to the shaft.

Means are provided for manually setting the rotative position of the bimetallic element 5I through rotation of the shaft 51 to provide different operating temperatures of the irons. The

longitudinal movement of the pin 62 with respect to the shaft 51 is provided so that at the time of manufacture a correct operative relationship may be established between the rotative position of the shaft 51 and the position of the bi-metallic element 5|. Thus, in assembling the iron the shaft 51 is rotated to the position it is designed to occupy when the iron is at its minimum operating temperature. The rod 62 is then rotated, for example, by engagement of the screw driver with the slot 66 until the bimetallic element 5| is held in a position at which warpage of the element will cause the circuit through the heating element to be made and broken at the desired temperatures. The ball 66 and cap 65 are then positioned at the upper end of the shaft to prevent accidental disturbance of the relationship thus established. After the establishment of this relationship the shaft 51 may be rotated so that the finger 5t will drop further away from the movable switch member, thus requiring a greater wai-page before the circuit will be opened. To accomplish this rotation of the shaft 51 the upper end of the shaft is splined, as shown at 61, and projects upward `through an opening 68 in the handle strap il. A lever support 69 is positioned on the upper side of the handle strap il and is secured thereto by the screws I6. The support is provided with an opening 1i for a purpose presently to be described. A lever 12 is rotatably positioned on the lever support 69 and in this instance is provided with a lining member 13 having internal teeth engaging the spline portion of the shaft 51. Thus, through rotation of the lever 12 the shaft 51 is correspondingly rotated. A space 14 is provided in the lever to permit of the vertical movement of the shaft 51 which accompanies its rotation. In order to visually indicate to the operator the position of the lever 12 and of the shaft 51 a plate 15, best shown in Fig. 5, is interposed between the handle strap Il and the lever support 69 and is provided with teeth 16 which engage the splines of the shaft 51. The plate 51 is provided with suitable inscriptions below the opening 1l in the lever support and visible therethrough, the plate '51 being moved longitudinallyalong the strap with rotation of the shaft 51 through the teeth 56, thereby selectively bringing the inscriptions under the opening 1i.

In order to make the bimetallic element 5i accurately responsive to the temperature of the ironing surface, that is, the bottom of the sole plate 1, I have arranged the mechanism so as to prevent, insofar as possible, changes of temperature in the pressure weight from being immediately reflected to the bimetallic element. To this end I have arranged the heating unit 32 so as to leave a space along the center of the heating element where no heat is being generated, this portion of the heating element being the portion directly covering the well i3. Furthermore, it will be seen that the heating element extends completely across the well I3 and substantially encloses the same. Thus, the top of the well is covered by a portion of the heating element in which no heat is being generated. Thus, because of the proximity of the bimetallic element 5I to the ironing surface of the iron and the construction of the heating element above the well I3 and the pressure weight the warpage of the bimetallic element becomes highly responsive to the temperature of the ironing surface and is not materially interfered with by the flow of heat from the superheated pressure weight above. As a. result of this construction the switching of the current will be substantially responsive to the temperature of the ironing surface regardless of the temperature of the remainder of the interior vof the iron. In other words, even though the pressure weight should become excessively heated by the continued ow of current through the heating element, the current would not be switched oil until the ironing surface of the sole plate 1 progresses above the predetermined minimum, as determined by the position of the lever 12. y

It will be seen from the preceding description that in my improved construction the thermostat is quickly responsive to temperature changes of the ironing surface and that the thermostat will be effective and maintain a flow of current so long as the ironing surface is below the ironing temperature regardless-of the temperature of the interior of the iron. The construction of the thermostatic control is highly simplified so as to materially reduce the cost of manufacture and the cost of assembling. For the purpose of.

ease of assembly the iron is made in a number of units. Thus, the bimetallic element 5i, the cylinder 55, shaft 51, and rod 62 are all formed as a part of the heating element and the terminals 22 and 28 are also connected thereto as a part of the unit. In assembling the device, the heating element and associated parts are placed on the top of the sole plate, the pressure weight is superimposed thereon and the bolts itl inserted. Thereupon, the cover 5 is placed over the pressureweight and heating element, the handle strap H is rested on the top and the lever 'l2 and lever support 69, which are formed as a unit, is rested upon the top of the handle strap whereupon the bolts i6 are inserted. At this point, the iron is tested and the position of the rod S2 set. The ball 58 and cap t5 are then inserted and a decorative cap 15 is inserted in the top of the lever 12. The handle l2 may then be attached and the assembling oi' the iron is complete. It will be seen that the adjustment ofv the thermostat is made after the iron is assembled, thereby eliminating danger of the setting being disturbed by the assembling operations. The small number of parts in the iron and the arrangement of the parts materially reduces the cost of manufacture and, in addition, reduces the possibility of trouble developing in the iron after it goes into service. Another important feature of the invention is the fact that the bimetallic element 5l is normally free of pressure. That is, when the iron is cool the bimetallic element merely rests against the bottom of the well i3 and no pressure is exerted thereon. Therefore, there is little or no tendency for the element to become permanently distorted to alter the accuracy of the setting. Attention is further directed to the fact that the construction permits the bimetallic ele/ment to be mounted in close relation to the bottom of the Well it so as to facilitate its response to the temperature of the ironing surface. The element need only be a sufficient distance from the bottom to permit of the manual adjustment or regulation thereof. Furthermore, the accuracy of the control is enhanced by the small number of operating parts due to the eliminating of looseness in the joints, etc. Another feature of the invention is the fact that the current for supplying the heating element at no time passes through any part of the thermostatic control mechanism.

While I have thus described andvillustrated ineens? a speciiic embodiment of my invention, I am aware that numerous alterations and Achanges may be made therein without materially departing from the spirit of the invention and the scope of the appended claims, in which-- I claim:

l. An electric sadiron having an ironing surface, electrical means for heating the same, a switch for controlling the supply of current, and a horizontally disposed rotatable oi-metallic element distortable under heat to actuate said switch, means for setting the position of said element to predetermine the switch actuating temperature comprising, a vertical member having threads, supported for advancement on the threads upon rotation, and means outside the iron for rotating said vertical member whereby to predetermine the temperature at which said switch is actuated.

2. In an electric sadiron having a cover, an ironing surface and a heating element, means for automatically controlling the temperature of said ironing surface comprising a bi-metallic element pivoted between its ends, an electric contact positioned to be broken by said element upon warpage thereof under increasing temperature, spring means located largely outside said cover for closing said contact, and manually operable means to vary the rotative position of said element to regulate the amount of warpage required to break said contact.

3. An electric sadiron having a heating element, a pivotally supported bi-metallic element arranged through warpage to break the circuit of said heating element, and means to vary the rotative position oi' said bi-metallic element including a member having threaded support on said heating element, means acting between said last mentioned member and said bi-metallic element for establishing a definite relationship therebetween, and means for manually rotating said member to vary the rotative position of said bi-metallic element to vary the temperature at which said circuit is brokenl 4. In an electric sadiron having an ironing surface and a heating element. means for controlling the temperature of said ironing surface comprising a bi-metallic element pivoted between its ends, an electric contact positioned to be broken by said element upon warpage thereof under increasing temperature, spring means for closing said contact, manually operable means to vary the rotative positionr of said element to reguate through 4a, predetermined range the amount of warpage required to break said contact, and means for predetermining said range. 5. In an electric sadiron having an ironing surface and a. heating element, means for controlling the temperature of said ironing surface comprising a bi-metallic element pivoted between its ends, an electric contact positioned to be broken by said element upon warpage thereof under increasing temperature, spring means for closing said contact, manually operable means to vary the rotative position of said element to regulateV through a predetermined range the amount of warpage required to break said contact, and means for rotating said element independently of said last mentioned means to predetermine said range.

6.Inan electricsadiionhaving anironing surface and a heating elemmt, means for controlling the temperature of said ironing surface comprising a bi-metallic element pivoted between its ends, an electric contact positioned to be broken by said element upon warpage thereof under increasing temperature, spring mears for closing said contact, manually operable means to vary the rotative position of said element to regulate through a predetermined range the amount of Warpage required yte break said contact, and means acting between said last mentioned means and said element for adjusting the relative positions thereof to predetermine said range.

7. In an electric sadiron having a cover, an ironing surface, and a heating element, means for controlling the temperature of said ironing surface comprising a lai-metallic element pivoted between its ends, an electric contact positioned to be broken by said element upon warpage thereof under increasing temperature, spring means for closing said contact, manually operable means to vary the rotative position of said element to regulate through a predetermined range the amount of warpage required to break said contact, indicating means outside said cover for indicating the breaking temperature of said contact, and means for rotating said element to cause the breaking temperature to correspond to the indicia of said indicating means.

8. In an electric sadiron having a cover, an ironing surface and a heating element, means for controlling the temperature of said ironing surface comprising a horizontally disposed bimetallic element pivoted between its ends, an electric contact positioned to be broken by said element upon warpage thereof under increasing temperature, a vertically disposed member movable toward and away from one end of said element upon manual rotation to rotate said element through a predetermined range and regulate the amount of warpage required to break said contact, and means operable from outside said cover for setting the relative position of said vertically disposed member and said element to predetermine said range.

9. In an electric sadiron having a cover, an ironing surface and a heating element, means for controlling the temperature of said ironing surface comprising a horizontally disposed bi-metallic element pivoted between its ends, an electric contact positioned to be broken by said element upon warpage thereof under increasing temperature, a vertically disposed shaft rotatable from outside the cover,v and a. pin extending axially through the shaft and threaded therein for setting the relative position of said shaft and said element to predetermine the temperature range, said pin being movable from outside the cover after the assembly of the iron for final adjustment thereof.

10. In an electric sadiron, a heating unit comprising a nat sheet-like heating element, e bimetallic blade pivotally secured to the lower surtace of said element, the element having an opening directly over one end of said element, an electrical contact point adjacent said opening for supplying current to the element, and means carried on the element over the opposite end of the blade rotatable to adjust the angular position of the latter.

IVAR JEPPSSON.

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