US1835552A - Thermostatically controlled switch - Google Patents

Description

A. M. YOUNG THERMOSTATICALLY CONTROLLED SWITCH Dec. 8, 1931. 1,835,552

Filed Jan. 8, 1930 Z Z6 44 Z4 I I {6 4 a T? 1 5 1 i5: Li j +3273 E L5 l 7 6 5 v INVENTOR /4//0W flZ)6U/7j ATTQRNEY5 Patented Dec. 8, 1931 UNITED STATES PATENT OFFICE ALLAN M. YOUNG, OI MIEBIDEN, CONNECTICUT, ASSIGNOR TO MANNING, BOWMAN &

00., OF MEBIDEN, CONNECTICUT,

A CORPORATION OF DELAWARE THERMOSTATICALLY CONTROLLED SWITCH Application filed .Tanuary 8, 1930. Serial No. 419,238.

My invention relates to a thermostatically controlled switch, and has special reference to a device of this character which is particularly adapted for use on electric sad irons and other electrically heated household utensils.

One of the objects of the present invention is to provide a device of this character which is simple in construction and reliable and accurate in operation.

Another object of the invention is to pro vide a device of this character which effects a quick make and break of the circuit without danger of arcing.

vide a novel and improved device of this character which ma be easily adjusted to meet different conditions. 1 The several features of the invention wherebythe above-mentioned and other objects may be attained, will be readily understood from the following description and accompanying drawings, in which:

Flgure 1 is a plan view of a thermostat1cally controlled switch embodying the features of my invention in their preferred form;

Fig.2 is a detail sectional view taken on the line 22 of Fig. 5; 1 Figs. 3 and 4 are views on an enlarged scale corresponding to a portion of Fig. 1 but showing operative parts of the switch in different positions; and

Figs. 5 and 6 are sectional Views taken respectively on the lines 5.5 and 66 of Fig. 1. The thermostatically controlled switch illustrated in the drawings is mounted on a base plate 2 which is adapted to be suitably secured upon a wall or other member 4 that may-constitute a art of an electric sad iron or other electrical y heated household utensil. As shown, the base is secured to the member 4 by means of rivets 6, and is insulated from the member 4 by a sheet of mica 8 and washers 10 of mica for-the heads of the rivets the rivets being spaced from the walls of the apertures through'which they extend in the base plate 2.

riveted or otherwise secured to anupstandis flexed outwardly as indicated by broken lines in Fig. 1. The usual rotatable cam member 16 may be associated with the bi-metallic element to regulate the degree of temperature at which the switch Will open, the cam being adapted to be forced against the outer side of the bi-metallic element.

In the illustrated construction, a channelshaped carrier 18 has one wall secured by rivets 20 to the inner side of the free end A further object of the invention is to pro of the bi-metallic element 12. An adjusting abutment screw 22 is screw-threaded through the free end of the bi-metallic ele- .ment and through the adjacent wall of the carrier 18 with its inner end directed toward the other sidewall of the carrier. The latter side .wall of the carrier has terminal contact screws 24 mounted therein with the screws suitably insulated therefrom and from each other, the heads of the screws being at the inside of said wall.

A leaf spring 26 extends between the abutment '22 and the heads of the terminals 24 and has its ends held in the upstanding arms of a U-shaped cradle 28 which may be made of phosphor spring metal. The ends of said eaf spring are so held as to cause the spring to be bowed so-that upon moving the spring in either direction pastits dead center, the

spring will snap into bowed position on one side or the other of its dead center, the arms of the spring metal cradle 28 yielding during such snapping action. The center of the leaf spring carries a stud 30 on the outer end' of which 1s secured a contact member 32 of silver which when the spring is in one bowed position bridges the heads of the terminal contacts 24, the contact disk 32 being loosely secured on the stud*'*80 so as to permit it to adjust itself to the two contacts.

With this construction,-the contact 32' is normally in firm bridging engagement with the heads of the terminal contacts 24. During the outward flexing of the free end of the bi-metallic element as the temperature rises, the terminal contacts are moved so as to act through the bridging contact to force the center of the bowed spring toward the bimetallic element, and upon the temperature reaching a predetermined degree, the spring is thus forced rearwardly past its dead center, whereupon it immediately snaps so as to quickly disengage the bridging contact 32 from the terminal contacts 24, thus opening the circuit. This snapping movement of the leaf spring is limited by the engagement of the rear end of the stud 30 with the end of the adjusting screw 22. During the lowering of the temperature, as the free end of the bi-metallic element moves toward its normal position, the abutment screw 22 forces the bowed leaf spring in the opposite direction until it passes its dead center, whereupon the spring snaps to quickly move the bridging contact 32 into bridging engagement with the terminal contacts 24.

Owing to the arcuate movement of the terminal contacts 24 from normal position to a point where the leaf spring snaps to disengage the bridging contact from the terminal contacts, the heads of the terminal contacts wipe over the surface of the bridging contact, and this wiping action increases as the contacts approach the position where breaking of the circuit is effected. In order to increase such Wiping 'action between the bridging contact and the terminal contacts previously to breaking the circuit, the points of connection of the ends of the leaf spring with the arms of the cradle28 are arranged in a line at a suitable angle, as shown in the drawings preferably three degrees, to the bimetallic element so that as the leaf spring is forced toward its dead center previously to snapping away from the terminal contacts, the center of the leaf spring and consequently the bridging contact tends to move in a direction gene-rally transverse to the heads of the terminal contacts. This wiping action between the terminal contacts and the bridging contact has been found to effectively prevent arcing during the separation of the contacts.

' By adjusting the screw 22 toward and from its point of engagement with the leaf spring, the degree of movement of the bi-metallic element toward its normal position necessary to effect closing of the switch during the lowering of temperature may be varied as desired, and thus the device may be adjusted so as to be extremely sensitive to any lowering of temperature after the switch has been opened.

It will be apparent that my improved device is of simple and cheap construction; may be easily and conveniently applied to electric sad irons and other electrically heated household utensils; operates without danger of arcing; and may be easily adjusted so as to insure quick breaking of the circuit when the temperature reaches a predetermined degree and quick closing of the circuit when there is any appreciable lowering of temperathe class described having, in combination, a

bi-metallic element having one end fixed and its other end free to flex under changes 1n temperature, an abutment carried by the free end of said element, terminal contacts car ried by the free end of said element and spaced from said abutment, a bowed leaf spring adapted to snap as it is forced by its dead center in opposite directions, a contact carried by said leaf spring and adapted to bridge said terminal contacts whereby when the free end of the bi-metallic element is flexed in one direction the terminal contacts through the bridging contact forces the leaf spring past its dead center so as to cause it to snap into engagement with said abutment to disengage the bridging contact from the terminal contacts and when the bi-metallic element is flexed in the opposite direction said abutment forces the leaf spring past its dead center so as to cause it to snap 'to re-engage the bridging contact with the terminal conspring being in a line arranged at a suitable angle to said bi-metallic element so that as the spring is moved toward its dead center to disengage the contacts, the contact on the spring tends to Wipe across the terminal contacts.

2. A thermostatically controlled switch of the class described having, in combination, a bi-metallic element adapted to flex under changes in temperature, an abutment carried by said element, a contact carried by said element and spaced from said abutment, a bowed leaf spring extending between said abutment and said contact and adapted to snap as it is forced by its dead center in opposite directions, a contact carried by said leaf spring and adapted to engage said first mentioned contact whereby when said bimetallic element is flexed in one direction said contacts force the leaf spring past its dead center so as to cause it to snap mto engagement with said abutment to disengage that as thespring is moved toward its dead center to disengage the contacts, the contact on the spring tends to wipe across the contact carried by said element.

3. A thermostatically controlled switch of the class described having, in combination, a bi-metallic element having one end fixed and its other end free to flex under changes in temperature, an abutment carried by the free end of said element, terminal contacts carried by the free end of said element and spaced from said abutment, a support, a bowed leaf spring extending between said abutment and terminal contacts and having its ends secured on said support to permit the center thereof to snap as it is forced by its dead center in opposite directions, a contact carried by said leaf spring and ada ted to bridge said terminal contacts where y when the free end of the bi-metallic element is flexed in one direction the terminal contacts through the bridging contact forces the leaf spring past its dead center so as to cause it to snap-into engagement with said abutment to disengage the bridging contact from the terminal contacts and when the bi-metallic element is flexed in the opposite direction said abutment forces the leaf spring past its dead center so as to cause it to snap to re-engage the bridging contact with the terminal contacts, the points of engagement of said ends of the leaf spring with said support being on a line arranged at a suitable angle to the bimetallic element so that as the bridging contact is moved by the terminal contacts to move the leaf spring past its dead center, the bridging contact tends to wipe over the terminal contacts previously to the disengagement of the bridging contact from the termi nal contacts.

4. A thermostatically controlled switch of the class described having, in combination, a

bi-metallic element having one end fixed and its other end free to flex under changes in temperature, a channel-shaped carrier having one side wallsecured to a side of the free end of said strip, an adjusting screw extending through said side wall, terminal contacts carried by the other side wall of said carrier, a U-shaped cradle, 11 bowed leaf sprin extending generall parallel with sai bimetallic element 'aving its ends held b the ALLAN M. YOUNG.

signed my sides of said cradle to permit the center t ereof to snap as it is forced by its dead center in opposite directions, a contactcarried by said leaf spring andadapted to bridge said terminal contacts whereby when the free end of the bi-metallic element is flexed in one direction the terminal contacts through the brid 'ng contact force the leaf springpast its dea center so as to cause it to snap into engagement with the end of said adjusting screw to disengage the bridging contact from the terminal contacts and when the bimetallic element is fixed in the opposite direction said adjusting screw forces the leaf

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