US2274390A - Control device for electric irons - Google Patents

Description

Feb. 24, 1942. w w s 2,274,390

CONTROL DEVICE FOR ELECTRIC IRONS Filed June 1'7, 1941 i; E@Y////////W/Q W W/ F g.2. a

2534 a 20 I7 3a 35 311 r O I 30 Z I Inventor": Walter- R. Weeks flwddw His Attorney Patented Feb. 24, v1942 2,274,390 CONTROL mavrcr. FOR ELECTRIC IRONS Walter R. Weeks, Hamden, Conn., asslgnor to General Electric Company, a corporation of New York Application June 17, 1941, Serial No. 398,419

6 Claims.

My invention relates to electric flatiron and the like and more particularly to means for automatically disconnecting the iron from the power supply when it is left idle in an ironing position.

In the use of electric flatirons damage is likely to result from fire, charring or scorching if the iron is inadvertently left connected to the power supply in an ironing position with the soleplate resting on a surface such as an ironing board. Hence, in order to prevent the possibility of such damage, it is desirable to provide means for automatically disconnecting the iron from the power supply in case the operator inadvertently leaves the iron in an ironing position.

It is an object of my invention to provide improved means for automatically disconnecting an electric flatiron from the power supply in case it is left unattended in a horizontal or ironing position.

Another object of my invention is to provide an improved means for disconnecting an electric flatiron from a power supply under certain conditions but at the same time to make this means inoperative when the iron is in an upright position on its heel stand.

It is a further object of my invention to provide improved means for disconnecting an electric flatiron from the power supply, the disconnecting means being effective while the iron is idle but ineffective during a horizontal movement of the iron while in use.

Another object of my invention is to provide safety disconnecting means for an electric flatiron which is simple and inexpensive in construction and which can be readily applied to a thermostatically controlled electric fiatiron of standard design.

Further objects and advantages of my invention will become apparent as the following description proceeds and the features of novelty which characterize my invention will be pointed out with particularity in the claims annexed to and forming a part of this specification.

Briefly, in accordance with my invention, I provide, in an electric fiatiron, a latch lever for releasably restraining the movement of a thermostatically controlled switch in the circuit closing direction once the latch lever has been set by an opening movement of the switch. The latching lever is normally effective but i rendered ineffective by a horizontal movement of the iron while in use. This is accomplished by the use of a pivotally mounted weight having extending therefrom a pin adapted to engage and I.

release the latch lever when the iron is moved. Hence if the iron is left idle the latch lever prevents recloslng of the switch once it has been opened by thermostatic action whereby the iron is automatically disconnected from the power supply.

My invention will be better understood from the following description taken in connection with the accompanying drawing in which Fig. 1 is a vertical elevation mainly in section of a flatiron having a safety control device embodying my invention; and Figs. 2 and 3 are views similar to Fig. 1 except that the safety control device is shown in different operating positions.

Referring to the drawing, I have shown, for the purpose of illustrating a specific embodiment of my invention, a fiatiron comprising a relatively heavy soleplate I0 made of suitable heat conducting material such as cast iron or aluminum within which is cast a suitable electric heating element ll. Although any suitable heating element may be used, preferably a heating element of the type described and claimed in Abbott Patent 1,367,341, dated February 1, 1921, will be used. This unit comprises an outer metallic sheath i2 suitably shaped and in which a helical heating element or resistor i3 is embedded in a suitable powdered heat refractory insulating material ll such as magnesium oxide. The unit is shaped preferably in the form of a horseshoe extending throughout a substantial portion of the soleplate Ill. The terminals I5 of the heating element are brought out at the heel of the iron and are electrically connected through the contacts of a thermostatic switch to be later described with a pair of suitable contact pins l6 which are arranged, as is well understood by those skilled in the art, to receive a plug receptacle of a suitable supply conductor.

As shown, the upper portion of the soleplate I0 is enclosed in a suitable cover l'l which is secured to the soleplate by suitable means such as screws (not shown). The iron is further provided with a suitable handle l8 secured to the cover ll.

Secured to the cover I! and extending rearwardly therefrom is a heel rest i9 which in conjunction with a projecting portion 2| of a plug guard 20 acts as a supporting means for sup porting the iron in an upstanding, non-ironing position.

For the purpose of maintaining the temperature of the iron within predetermined limits, I provide a thermostatically operated control switch 23 which is connected in series circuit relation with the electric heating element l3. The

nected to one of the contact pins l6 while the other is electrically connected to one of the terminals l5 of the electric heating element by a suitable electrical connecting means not shown. The stationary contacts 24 are arranged to be bridged by a bridging member 24a which i insulatingly mounted on one end of a movable switch arm 26. The other contact pin I6 is electrically connected to the remaining terminal [5 of the heating element 13 so that the switch arm 26, in moving the bridging member 24a into and out of engagement with the stationary contacts 24, acts to control the energization of the heating element.

The thermostatic mechanism for controlling the movement of the switch arm 26 comprises a bimetallic thermostatic bar 21 made of two strips of metal having dissimilar temperature coeflicients of expansion such as iron and steel, the

strips being securely brazed or welded together throughout their length. One end of the bar 21 is rigidly secured to the soleplate ill by means of a clamping screw 28, the bar being arranged so that the other end deflects upwardly when heated. The other end of the bimetallic bar is provided with a knife edge bearing 29 which rests in a bearing seat provided for it in one arm of an inverted Ushaped resilient spring member 30. The other arm of this spring member is seated on a fixed knife edge bearing 3|. This fixed bearing is adjustably secured to the soleplate In by means of a screw member 32. In the specific form of thermostatic mechanism illustrated the switch arm 26 is connected to the upper portion of the U-shaped spring 30 by means of special connecting means 33 designed to permit a limited relative movement between the switch arm and the spring. A detailed explanation of the operation of the special connecting means 33 will be omitted as it is not necessary for an understanding of the present invention.

The operation of the thermostatic control mechanism thus far described is entirely conventional. It will be understood that when the temperature of the iron rises above a predetermined value the free end of the bimetallic bar 2! moves upwardly causing the U-shaped spring member 30 to snap overcenter and thereby cause the switch arm 26 to move upwardly and disengage the contacts of the control switch 23 to disconnect the heater element l3 from the power supply. Similarly, when the temperature of the iron falls below the predetermined value the free end of the bimetallic bar moves in the opposite direction causing the spring member 30 to snap back to its original position and the switch arm 26 to move downwardly thereby bringing the contacts of the switch 23 into engagement to reestablish the energizing circuit for the heater element.

In accordance with my invention I provide means for latching the control switch 23 in the open circuit position after it has once been opened by the action of the thermostat and means responsive to a. horizontal movement of the iron for rendering the latching means ineffective. In accordance with the illustrated embodiment of my invention this is accomplished by apparatus which will now be described.

Mounted upon the switch arm 26 for pivotal movement relative thereto is a latch lever 35, one end of which is connected to the switch arm by means of a pivotal connection 36. The opposite ,end 31 of the latch lever 35 depends from the switch arm and is free to swing relative thereto.

Extending upwardly from the soleplate in approximate vertical alignment with the pivotal connection 36 is a projection 31, the top portion of which is shaped to form a. receiving seat 38 into which the free end 31 of the latch lever 35 is adapted to fall when the switch arm 26 moves to the upper or open circuit position shown in Fig. 2. When the free end 31 of the latch lever 35 engages the receiving seat 38, as shown in Fig. 2, the latch lever acts as a prop preventing a closing movement of the switch arm 26 by action of the bimetallic bar 21. The closing of the contacts of the control switch 23 is thereby prevented until the latch lever 35 is disengaged from the receiving seat 38 so that the free end of the lever 3! lies alongside the projection 31 as shown in Fig. 1.

In order to provide means for disengaging the latch lever 35 from the receiving seat 38 while the iron is in use and thereby permit normal control of the contacts of the control switch 23 under action of the thermostat, I provide a weight 40 mounted for movement relative to the soleplate of the iron. In the illustrated form the weight 40 comprises a body portion 4| and a pair of downwardly extending wedge-shaped legs 42, only one of which is shown. It will be understood that the weight 40 has a generally U-shaped cross-section and the bimetallic bar 21 extends between the legs 42. The soleplate I0 is provided with a V-shaped notch 43 into which the legs 42 of the weight 40 are adapted to extend. The notch 43 is considerably larger than the wedge-shaped legs 42 of the weight so that the weight is free to oscillate frontwards and backwards a limited amount about a pivot formed by the engagement of the lower end of the legs with the bottom of the notch 43. The center of gravity of'the weight is arranged to be slightly ahead of the pivot point so that the weight normally tips forward, the legs 42 contacting the forward wall of the notch 43 as shown in Fig. l. Extending rearwardly from the weight 40 and formed integrally therewith is a projecting pin 44. Upon a forward movement of the iron during the ironing operation the weight 40 tips backward in the notch 43 causing the end of the pin 44 to engage the latch lever 35 and swing the free end 31 of the latch lever out of engagement with the receiving seat 38. Therefore, it is apparent that the to and fro movement of the iron while in use will cause the weight 40 and the pin 44 to repeatedly move backward and forward and render the latch lever ineiiective so that the control switch 23 is free to operate under thermostatic control in a normal manner,

When the iron is placed in the upstanding position in which it is supported on the heel stand l9 and the projection 2|, there is no danger of damage from burning or scorching and it is de' sirable that the safety latching means be rendered ineffective in this position so that the iron may be left unattended while initially heatinr.

and the temperature of the iron maintained while resting in this position between ironing periods. It will be observed that the pivotally mounted weight automatically accomplishes this desired function. Thus, when the iron is placed in the vertical position, the legs of the weight 40 rest in contact with the rear wall of the notch 43 so that the pin 44 engages the latch lever 35 and keeps it out of engagement with the receiving seat 38 whereby the thermostat is free to control the switch 23 and maintain the iron at desired temperature.

In operation, if the operator leaves the iron idle in a horizontal position, the weight 40 will move by gravity to the forward position in the notch 43 so that the pin 44 is out of engagement with the latch lever 35 as shown in Fig. 1. When the iron temperature rises to a predetermined value the thermostat will move the switch arm 26 upwardly opening the control switch 23 and disconnecting the heating element. In this position the latch lever 35 will swing by gravity to a point directly over the receiving seat 38. When the iron cools and the thermostatic bar begins to move the switch arm 26 downwardly toward the closed circuit position, the latch lever engages the receiving seat and acts as a prop preventing closure of the switch 23 as shown in Fig. 2. Thus it is seen that the iron is automatically disconnected from the power supply and will eventually cool down to room temperature if the iron is left unattended.

When the operator resumes the to and fro ironing movement or places the iron in a vertical position on the heel rest, the weight 40 will move backward to the position shown in Fig. 3 causing the pin 44 to knock the latch lever 35 out of engagement with the receiving seat 38 thereby permitting the thermostat to move the switch arm 26 downwardly to close the switch 23 and reconnect the heating element to the power supply. The heating of the soleplate will then be resumed until the thermostat again opens the control switch 23.

Thus it will be seen that as long as a horizontal to and fro movement is imparted to the iron by the operator the weight functions to render the latch lever 35 ineffective. However, as soon as the movement of the iron ceases, the latch lever becomes effective to lock the control switch in the open circuit position thereby effectively to disconnect the iron from the power supply.

From the foregoing it will be apparent that I have provided simple and inexpensive control apparatus applicable to a thermostatically controlled electric iron which will function dependably to disconnect the iron from the power supply in case it is left in the horizontal ironing position by the operator.

While I have shown and described particular embodiments of my invention, it will occur to those skilled in the art that various changes and modifications may be made without departing from my invention, and I, therefore, aim in the appended claims to cover all such changes and modifications as fall within the true spirit and scope of my invention.

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

1. In an electric fiatiron the combination with a heating element and an energizing circuit therefor of a control switch for controlling said circuit, thermostatic means responsive to the temperature of said iron for opening and closing said switch, said switch comprising a movable switch arm, a latch lever pivotally mounted to said switch arm and arranged to depend therefrom, a fixed receiving seat located vertically below said latch lever, said latch lever being adapted to engage said seat and act as a prop to prevent movement of said switch arm in a direction to close said switch, a weight mounted for movement relative to said iron, said weight being normally in a first position when said iron is idle but moving to a second position upon movement of said iron while in use, and means responsive to a movement of said weight from said first to said second position for moving said lever out of engagement with said seat whereby said switch arm is permitted to move in a direction to close said switch.

2. In an electric flatiron having a heating element and an energizing circuit therefor, a switch for controlling said circuit, said switch comprising a movable switch arm, thermostatic means responsive to the temperature of said iron for moving said switch arm to open said switch when the temperature of said iron exceeds a predetermined value, a latch member pivotally mounted on said switch arm and normally engaging a receiving seat to preclude movement of said switch arm to close said switch, and means responsive to a movement of the iron during use for moving said lever out of engagement with said seat to permit a switch closing movement of said switch arm.

3. In an electric flatiron the combination with a heating element and an energizing circuit therefor of a switch for controlling said circuit, means responsive to temperature of said iron for opening said switch when the iron reaches a predetermined temperature, means for latching said switch in the open position, a weight pivotally mounted on said iron, said weight normally occupying a first position while the iron is idle in an ironing position but being arranged to move to a second position upon movement of the iron while in use, and means responsive to a movement of said weight to said second position for rendering said latching means ineffective.

4. In an electric fiatiron the combination comprising a control switch for controlling a heating circuit of said iron, thermostatic means responsive to the temperature of said iron for opening and closing said switch, means for latching said switch in the open position, and means responsive to movement of the iron while in use for rendering said latching means ineffective.

5. In an electric flatiron the combination comprising a control switch for controlling a heating circuit of said iron, thermostatic means responsive to the temperature of said iron for opening and closing said switch. means for latching said switch in the open position, a weight mounted to move relative to the iron during movement of the iron while in use and means controlled by the movement of said weight for rendering said latching means ineflective.

6. In an electric flatiron the combination with to movement of the iron while in use for rendering said latching means ineii'ective.

WALTER R. WEEKS.

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