US2681521A

US2681521A - Thermostatically controlled electric flatiron or the like

Info

Publication number: US2681521A
Application number: US240084A
Authority: US
Inventors: Frank E Finlayson; Alfred G Swenson
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1951-08-03
Filing date: 1951-08-03
Publication date: 1954-06-22
Anticipated expiration: 1971-06-22

Description

June 1954 F. E. FINLAYSON El'AL 8 THERMOSTATICALLY CONTROLLED ELECTRIC FLATIRON OR THE LIKE 2 Sheets-Sheet 1 Filed Aug. 3, 1951 Pa g1.

Inventor's: Frank E. Finlagson,

Neil Herman, Alfred G. Swen on,

T heir- Attorneg,

June 22, 1954 F. E. FINLAYSON ETI'AL THERMOSTATICALLY CONTROLLED ELECTRIC FLATIRON OR THE LIKE Filed Aug. 3, 1951 2 Sheets-Sheet 2 Inventors: Frank E. F'inlagson, Nei'l Herman,

Alfr-ecl G. Swanson,

Their Attorne g.

thermostat.

.and I2. plate l4 attached toxthe handle by a screw it I the fiatiron terminals. LjBCtS beyond the end of soleplate I, the opening Patented June 22, 1954 UNITED STATES PATENT OFFICE THERMOSTATICALLY CONTROLLED ELEC- TRIC FLATIRON OR THE LIKE poration of New York Application August 3, 1951, Serial No. 240,084

11 Claims.

The present invention relates to electric flatirons wherein an adjustable thermostat is provided for regulating the temperature of the flatiron and more particularly to the thermostat structure and the arrangement of mounting the thermostat in the flatiron.

The primary object of the invention is to provide an improved mechanism which is simple in structure whereby it is capable of being manufactured at low cost but which at the same time is stable and reliable in operation and has little tendency to temperature overshoot. According to one feature of the invention, the bimetal of the thermostat is supported on the soleplate of the flatiron independently of the frame of the thermostat and only a single spring is employed in connection with the mounting of the contacts and for their operation and adjustment.

The invention and its advantages willbe understood from the following description taken in conjunction with the accompanying drawing.

In the drawing, Fig. 1 is a longitudinal sectional view of a flatiron embodying the invention; Fig. 2 is a top plan view of the soleplate and thermostat; Fig. 3 is a sectional view on a smaller scale taken on line 3-3 of Fig. 2; Figs. 4 and 5 are detailed views illustrating the operation of the thermostat structure; Figs. 6 and '7 are sectional views of certain parts; Figs. 3 and 9 are detail, sectional and plan views of a modification; and Figs. 10 and 11 are similar views of a further modification.

Referring to the drawing, I indicates the soleplate of a fiatiron and 2 the electric heating unit which is cast into the soleplate and has terminals 3 and 4 at the rear end of the flatiron. Positioned on the soleplate is the top shell Sywhich is attached to the soleplate by screws 6 which pass through openings in shell 5 and thread into openings l in the soleplate. Shell 5 and soleplate I together form a supporting structure for the Attached to shell 5 by a suitable arrangement of screws, one of, which is shown at 8, is a handle 8 having a grip portion l and hollow front and rear posts I I and. 12 which house parts of the flatiron. Screws 6 are located one on each side of the soleplate and areconcealed by a cover plate [3 suitably attached to posts I! At the rear of the handle is a cover which cover plate, when removed, gives access to At its rear "shell probeing covered by a removable plate 16.

The structure so far described is a known one and is to be taken as typical of any suitable flatiron construction.

In carrying out the invention in accordance with the illustrated embodiment in Figs. 1-7 inelusive, soleplate l is provided with three bosses l1, l8, and 19 for supporting the thermostat structure on the soleplate. Bosses H, and 18 are located centrally and on opposite sides of soleplate l, and boss 19 is located forward of bosses I? and I8 and about midway between the side edges of the soleplate.

The thermostat comprises a rectangular metal frame having a front bar 20, side bars 2i and 22 and a rear bar 23. The frame is rigid and is fixed on bosses H. and 18 by screws 24. The rame is spaced from the soleplate except for its engagement with the tops of bosses ll and !8. Rear bar 2-3 is in the form of a pad which supports a terminal block 25 of insulating material, the block being attached to and positioned on the pad by rivets or eyelets 2t and by cars 27 on the side edges of the pad which engage recesses in the side edges of the block.

The terminals for the fiatiron are indicated at 28, 29, and 30. Terminal 28 is attached to block 25 by rivets 3| as shown in Fig. 4 and its rear end is turned upwardly and is provided with a threaded opening to receive a terminal screw for use in wiring the flatiron. Anchored on block 25 under terminal 28 is a leaf spring 32 on the free end of which is fastened an insulator 33 which engages the face of a flat thermostat adjusting cam 34. Cam 34 is in the form of a disk rotatably mounted on front bar 20 of the thermostat frame by an eyelet 35. It is shaped to provide upwardly facing sloping cam surfaces upon which insulator 33 rides, the insulator being held against the cam face by the resiliency of leaf spring 32 so that when the cam is turned, the leaf spring will follow its movement. Attached to leaf spring 32 adjacent to its free end by suitable means such as by riveting or welding is an offset bracket or leg 36 which extends rearwardly alongside of the leaf spring to a point adjacent to insulator 25 and has a contact button 3'! on its free end. Bracket or member 36 is formed from material heavier than leaf spring 32- and insofar as operation of the thermostat is concerned, it is rigid. It is attached to the leaf spring at a point such that its end is over the cam face. Thus this end of the bracket is directly supported by the cam. This is one important feature of the improved construction as is pointed out hereinafter. The outer ends of leaf spring 32 and bracket 36 cooperate to form a holding means for insulator 33. To this end, bracket 36 is provided with a projecting end 38 (see Fig. '7) which fits in a rectangular opening 33 in insulator 33 and the free end of leaf spring 32 is provided with an ofiset spring tongue 35 which is also positioned in opening 33. With this arrangement, the insulator 33 maybe mounted on the end of the leaf spring by pressing projecting end 38 of the bracket and the spring tongue 49 through the rectangular opening in the insulator to the position shown in the Fig. '7. This serves to hold the insulator firmly on the end of the leaf spring. This makes a convenient mounting arrangement which is simple instructure, easy to assemble and which avoids the use of cement or other similar fastening means.

Terminal 29 is riveted to block 25 after the manner shown in Fig. 4 for terminal 28. At its inner end it is provided with a thermostat contact button 62 which stands above and cooperates with contact button 3"! and at its outer end with a terminal binding screw 43 for use in wiring the fiatiron. Terminal 36 is riveted to block 25 as shown at M and its upturned end is provided with a threaded opening to receive a binding screw for use in wiring the flatiron. In wiring the fiatiron terminal 3 is connected to terminal 23 as indicated at 36a, and terminal i is connected to terminal 36 as indicated at 28a. The terminals of the fiatiron cord (not shown) are connected to

terminals

28 and 36.

Fixed to boss l9 by a screw 45 is the bimetal d6 of the thermostat. It may be of any suitable type. In the present instance we have shown a bimetal such as that described in the patent of Winborne 2,128,869, August 30, 1938. Attached to the outer end of bimetal 36 is a U-shaped bracket 47, the free end of which stands over bracket 36 and in such end is an adjusting screw front bar 26 and is arranged to be turned for manually adjusting the cam by a vertical shaft 5! the lower end of which is pivoted in the opening through eyelet 35, it having a lower end of reduced size which provides a shoulder which takes against the top of the eyelet, and the upper end of which is pivoted at the top of post it as shown at 52. Shaft 55 is attached to cam 3 for turning it by an arm 53 fixed on the lower end of shaft 5! and provided with a finger 5% which engages in a notch 55 in the edge of the cam. At its upper end, shaft 5i is provided with a thermostat adjusting arm 56 which projects out through an arcuate slot 5? in handle post Ii and has a knob 58 on its end for use in turning the arm and shaft. In slot 57 is a plate 53 on which is marked a temperature scale for use in adjusting the thermostat.

Attached to terminal 26 is a bracket 66 which carries an indicating lamp 6! which may be wired in parallel with heating unit 2 for indicating when the circuit of the thermostat is closed and the fiatiron is heating. At 62 is an angle-shaped finger which is used as a guide in assembling the bimetal 46 and which serves also to insure that bracket 4? will not move over and contact live V 4 bracket 36 in case the bimetal assembly should loosen.

The fiatiron operates in the well-understood manner. When the high point of cam 34 is under insulator 33, this being the oif position of arm 56, spring 32 is flexed to bring bracket 36 into engagement with the inner end of insulating button it to separate the

contacts

31 and 42 and hold them separated. This is the position of the thermostat shown in Fig. 5 and in this position the circuit to the heating unit through the thermostat contacts is permanently open. To put the fiatiron into service, cam 34 is turned in a clockwise direction as viewed in Fig. 2 to move the cam with respect to insulator 33. When the cam is turned, the insulator rides down the cam surface. The spring 32 due to its resiliency keeps the insulator in firm contact with the cam surface and follows the movement of the insulator. Ihis results in bracket 36 pivoting on the end of insulating button 49 to permit contact 31 to move into engagement with contact 2 to close the circuit on the heating unit. Continued movement of the cam in the same direction after contacts 3i and 42 are touching causes bracket 36 to move away from insulating button 43. This is the position of the thermostat parts shown in Fig. 1, which shows cam 34 set for an intermediate heat. Now the flatiron heats and as it heats, bimetal 46 begins to flex in a downward direction and when the temperature for which the thermostat is set is reached, it brings the end of insulating button 49 into engagement with bracket 36 to move contact 3'! from engagement with contact 42 as shown in Fig. 4, thus opening the circuit on the heating unit 2. Now as the fiatiron is used and fluctuates in temperature, the thermostat closes and opens

contacts

31, 42 to maintain the temperature at the value for which the cam is set.

By turning cam 34, the thermostat can be adjusted for the desired temperature as is well understood.

In Figs. 8 and 9, we have shown a modification wherein the part corresponding to bracket 36 of Figs. 1-7 is in the form of an offset bracket or leg 3t formed integral with spring 32 which corresponds to spring 32 of Figs. 1-7. In other words the spring 32 and bracket or leg 36 are made up of a single piece which includes a spring part extending from the cam 34 to the terminal block 25 and a bracket or leg 36 which carries the movable contact. The bracket or leg 36 is preferably made relatively wide as shown in Fig. 9 to give it the desired rigidity. Otherwise, the construction shown in Figs. 8 and 9 may be similar to that shown in Figs. 17 and reference numerals corresponding to those of Figs. 1-7 with the exponent it added have been used to designate corresponding parts.

In Figs. 10 and 11 is shown a further modification wherein the spring and movable contact carrier corresponding to spring 32 and bracket 36 of Figs. 1-7 are in the form of a spring strip folded back on itself as indicated at 63 to provide a spring part 64 and a movable contact carrying bracket or leg part 65, there being an arm 66 fixed to the strip which at its free end carries an insulator 33 which bears on the thermostat adjusting cam. With this arrangement spring part 64 and arm 66 together correspond to spring 32 of Figs. 1-7 and bracket or leg part 65 which is constructed to give it the desired rigidity corresponds to bracket 36 of Figs. 17. Otherwise the construction shown in Figs. 10 and 11 may bersimilar to thatishown in Figs. 1- .andreference numerals corresponding to those of Figs. 1-7 Withthe exponent b added havebeen used to designate corresponding parts.

his to be noted that the improved thermostat employs only a single spring which at one end is anchored on the insulator at the one end of the frame and at the other end is supported by the active face of the cam, the arrangement being such that the leaf spring is flexed by an amount to maintain the insulator at the free end of the leaf spring-in firm-engagment with the active face of the cam for all adjustments of the cam, and that the movable contactand the bracket or leg to which it is fixed are carrieddirectlyby the leaf spring. Thus a single leaf spring serves directly as the contact carrier and as the spring means for biasing the movable contact into firm engagement with the fixed contact.

When the "contacts are in engagement, as shown in Fig. 1, for example, bracket 36 is firmly held at both of its ends, the one end being held by cam 34 and the other endby fixed contact 42. Since this is the part which is directly acted on by bimetal 46 and is a rigid member, the operation of the thermostat will not be affected by such dimensional variations in leaf spring -32 as are met with inthe manufacture of leaf springs. This is an important 'consideration in helping to give stability of operationof the thermostat.

Similarly in the case of the modifications shown in Figs. 8 and 9 and Figs. 10 and 11, the

brackets or legs which carry the movable contact are firmly held at both ends when the movable contact is in engagement with the fixed contact. In addition, since the bracket which functions as the contact breaker, is a rigid member firmly supported at one end by the cam and normally resting against the stationary con tact at the'other end, the bimetal works against a rigid and well-supported member which does not change its shape as does a spring, for example. This helps to make the thermostat operate more accurately. Also, the arrangement has the further advantage'that the contact pressure varies but slightly between one setting of the cam and another, the variation being so slight as tobe inconsequential.

The mounting of bimetal 46 on a separate boss independently of the thermostat frame has the advantage that the thermostat is not affected by the temperature of the relatively heavy frame but is affected only by the temperature of the soleplate itself; and since this is the part the temperature of which is to be regulated, the arrangement serves to give improved temperature regulations as compared to an arrangement wherein the bimetal is carried by the thermostat frame.

What we claim as new and desire to secure by Letters Patent of the United States is:

1. In an electric flatiron, a soleplate having a pair of bosses positioned adjacent opposite sides of the flatiron and a third boss spaced from said pair of bosses, a rigid thermostat frame fixed on said pair of bosses, an adjusting cam pivoted on the frame, a leaf spring having one end fixed to the frame and the other end engaging said cam, a contact bracket carried by said leaf spring, a thermostat contact on the contact bracket, a second thermostat contact carried by said frame and positioned to be engaged by said first-named thermostat contact, a bimetal fixed on said third 6 boss, and means carried by the bimetal and engaging :said contact bracket for effecting movement of said contacts relatively to each other.

2. -In an electric fiatiron, a soleplate having a pair of spaced bosses and a third boss in spaced relation to 'said pair of bosses, a thermostat frame fixed on and supported by said pair of bosses,:an adjusting cam mounted on the frame, a leaf spring fixed at one end on the frame, its otherend riding on the surface of said cam, a bracket carried by said leaf spring, a movable thermostat contact on "the bracket, a stationary thermostat contact carried by said frame in position to be engaged by said movable contact, a bimetal fixed on said third boss, and a member 'carriedby said bimetal adapted to engage saidbracket for flexing said leaf spring to effect movementof said movable contact into and out of engagement with said contact.

3. The combination with a supporting structure, of thermostatic means comprising an adjusting means mounted on the structure, a leaf spring-having one end fixed on the structure at a point remote from said adjusting means, the free end of the leaf spring engaging the adjusting means and being stressed by the same, a fixed thermostat contact supported on the structure, an offset member carried by the leaf spring, a movable thermostat contact carried by said member and positioned to engage the fixed thermostat contact, a bimetal mounted on the structure, and means carried by the bimetal. adapted to engage said member to effect movement of the movable thermostat contact into and out of engagement with saidfixed thermostat contact.

4. The combination with a supporting structure, of-thermostatic means comprising adjusting means mounted on the structure toward one end thereof, a leaf spring having one end fixed on the structure at the other end thereof, the freeend of the leaf spring engaging the adjusting means and being stressed by the same, a fixed thermostat contact supported on the structure, a bracket'carried by the spring, a movable thermostat contact carried by said bracket and positioned to engage the fixed thermostat contact, a bimetal mounted on the structure, and means carried by the bimetal adapted to engagesaid bracket to effect movement of the movable thermostat centact into and out of engagement with said fixed thermostat contact.

5. The combination with a supporting struc ture of thermostatic means comprising an adjusting means mounted on the structure toward one end thereofya leaf spring having one end fixed onthe structure at the other end thereof, the free end of the leaf spring engaging the adjusting means and being stressed by the same, a fixed thermostat contact carried by the structure, a bracket attached to the free end of the spring at a point such that the end of the bracket is engaged by the adjusting means and is supported thereby, a movable thermostat contact carried by said bracket and positioned to engage the fixed thermostat contact, a bimetal mounted on the structure, and means carried by the bimetal adapted to engage said bracket to effect movement of the movable thermostat contact into and out of engagement with said fixed thermostat contact.

6. In combination, a supporting structure, a rectangular thermostat frame supported on the structure, an adjusting means mounted on the frame at one end of the frame, a leaf spring having one end fixed on the other end of the frame, the free end of the leaf spring engaging said adjusting means and being stressed by it, a fixed thermostat contact carried by the frame, a bracket attached to the free end of the spring at a point such that the end of the bracket is over the active face of the adjusting means and is held thereby, a movable thermostat contact carried by said bracket and positioned to engage the fixed thermostat contact, a bimetal mounted on the supporting structure, and means carried by the bimetal adapted to engage said bracket to effect movement of the movable thermostat con-- tact into and out of engagement with said fixed thermostat contact.

'7. In combination, a supporting structure, a rectangular thermostat frame supported on the structure, an adjusting means mounted on the frame toward one end thereof, a leaf spring hav ing one end fixed on the frame at the other end thereof, the free end of the leaf spring engaging the adjusting means and being stressed by the same, a fixed thermostat contact on the frame, a bracket attached to the spring at a point adjacent to the adjusting means, said bracket extending along said leaf spring and having a movable thermostat contact positioned to engage the fixed thermostat contact, a bimetal mounted on the structure, and means carried by the bimetal adapted to engage said bracket to effect movement of the movable thermostat contact into and out of engagement with said fixed thermostat contact.

8. In combination, a supporting structure, a rectangular thermostat frame supported on the structure, an adjusting cam pivotally mounted on the frame at one end of the frame, a leaf spring having one end fixed on the other end of the frame, the free end of the leaf spring engaging the active face of said cam and being stressed by the cam, a fixed thermostat contact carried by the frame, a bracket attached to the free end of the spring at a point such that the end of the bracket is against the active face of the cam and is held thereby, a movable thermostat contact carried by said bracket and positioned to engage the fixed thermostat contact, a bimetal mounted on the structure, and means carried by the bimetal adapted to en age said bracket to effect movement of the movable thermostat contact into and out of engagement with said fixed thermostat contact.

9. In combination, a supporting structure, a rectangular thermostat frame supported on the structure, an adjusting cam pivotally mounted on the frame at one end of the frame, a leaf spring having one end fixed on the other end of the frame, the free end of the leaf spring engaging the active face of said cam and being stressed by the cam, a fixed thermostat contact carried by the frame adjacent to the end of the frame at which the leaf spring is fixed, a bracket attached to the free end of the spring at a point such that the end of the bracket is against the active face of the cam and is held thereby, said bracket extending along said leaf spring and havin thereon a movable thermostat contact positioned to engage the fixed thermostat contact, a bimetal mounted on the structure, and means carried by the bimetal adapted to engage said bracket to effect movement of the movable thermostat contact into and out of engagement with said fixed thermostat contact.

10. In combination, a supporting structure, an adjusting means mounted on the structure, a leaf spring means having one end fixed on the structure at a point remote from said adjusting means, said spring means being in engagement with and stressed by said adjusting means, a fixed thermostat contact on the supporting structure, a movable thermostat contact carried by the leaf spring means positioned to engage said fixed thermostat contact, and a temperature responsive element on the supportingstructure which engages said spring means to effect movement of the movable thermostat contact into and out of engagement with said fixed thermostat contact.

11. In combination, a supporting structure, leaf spring means which at one end is fixed on the supporting structure and extends across it, an adjusting member on the supporting structure against which the leaf spring means rests at a point remote from its fixed end and which holds the leaf spring means under tension, a fixed thermostat contact on the supporting structure, a movable thermostat contact carried by the leaf s ring means positioned to engage said fixed thermostat contact, and a temperature responsive element on the supporting structure which engages said leaf spring means at a point between said movable thermostat contact and said adjusting member to effect movement of the movable thermostat contact into and out of engagement with said fixed thermostat contact.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,582,02 i Finlayson Jan. 8, 1952 2,582,773 Finlayson Jan. 15,1952 2,602,248 Finlayson July 8, 1952