US1627732A - Thermostatic control for electric ovens and the like - Google Patents

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y E. 1.. FONSECA THERMOSTATIC CONTROL FOR ELECTRIC OVENS AND THE LIKE Filed Sept. 11 1924 2 Sheets-Sheet l INVENTOR BY'M V ATTORNEYS Mai 10' I927.

y E. 1.. FONSECA THERMOSTATIC CONTROL FOR ELECTRIC OVENS AND THE LIKE 2 Sheets-Sheet 2 Filed Sept. 11 1924 INVENTOR Z M w llcq HM/U W ATTORNEYS Patented May '10, 1927.,

UNITED STATES PATENT OFFICE.

EDWARD L. -FONSECA, OF NEWARK, NEW JERSEY, ASSIGNOR, BY MESNE ASSIGN- MENTS, TO THE WILCOLATOR COMPANY, OF NEWARK, NEW JERSEY, A CORPORA- TION OF DELAWARE.

THEBMOSTATIC CONTROL FOR ELECTRIC OVENS AND THE LIKE.

Application filed September 11, 1924. Serial No. 737,049.

My invention relates to a thermostatic con trol for electric ovens, and has to do particularly with a three point switch which is controlled by thermostatic means so that one circuit may be closed when the oven is below the desired temperature and a second circuit may be closed when the desired oven temperature is reached. These circuits may include any well known form of apparatus intended to control the main circuit which supplies the electricity to the heating elements of the oven but such apparatus and the particular manner in which it is connected form no part of my present invention. In the accompanying drawings which show illustrative examples of devices embodying my invention Fig. .1 shows a plan .view of one form of such device with the cover-plate removed; Fig. 2 is a longitudinal section of l the device shown-in Fig. 1; Fig. 3 is a section on line 3-3 of Fig. 2; Fig. 4 is a perspective view showing a way in which the device may be mounted on the stove; Fig. 5

is a longitudinal sectional view of a modified form of device with a portion of the oven well illustrated; Fig. 6 is a fragmentary end view of the device shown in Fig. 5, but without the oven wall, and Fig. 7 is a plan view of this form of device with a portion of the cover plate broken away.

Referring particularly to Figs. 1, 2 and 3, 10 is a base plate which has one end bent out at 11, where an opening 12 is provided for the cable containing the connecting wires as illustrated in connection with the form of device shown in Fig. 7. Attached to the base plate 10 are two brackets 13 and 14. These brackets must be insulated from the base plate and from each other, and I find this can be done quite cheaply by providing openings 15 considerably larger in diameter than the attaching bolts 16, and by covering both faces of this portion of the base plate 10 with mica strips 17 in which areopenings just large enough to receive bolts 16. The mica strips 17 are held in place by rivets 18. Pivotally mounted in bracket '13 is an arm 19 which carries a double fa ced contact 20. A spring .21 exerts pressure to'force the arm 19 towards base plate 10. In the same way bracket 14 carries an arm 22, which has position shown in Fig. 2. A third contact 26- is carried by a plate 27, which is attached to base 10. Three wires 28,29 and 30 are connected to brackets 13 and 14 and plate 27 respectively.

When the parts thus far described are in the positions shown in Fig. 2 in which one face of contact is in engagement with contact 26, and the other face is-spaced from the'contact 23, the wires 28 andare connected and the wires 28 and 29 are disconnected. If arm 19 is moved to carry its free end away from plate 10, the circuit connection from Wire 28 to wire 30 will be broken and on further movement of the arm 19, contact 20 will engage contact 23 and thus elec trically connect wires 28 and 29.

In order to move arm 19 I supply a push "rod 31 which slides in a bearing 32 attached tobase 10. The outer end of rod 31 contacts with arm 19 While the inner end con tacts w th thermostatic element 33. In the "example shown this element/is of the type made of two strips of materials having different temperature coefiicients, the composite strip being adapted to bend under the influence of heat and this is the form of thermostat which I prefer to use. However other forms of thermostatic elements may be used and still retain many of the advantages of my invention.

The thermostatic element 33 is rather loosely mounted at one end and at the other end is pivotally connected 1 with the threaded sleeve 35; The sleeve 35 moves on thescrew 36 which rotates in a bearing 37 and has on its outer end a small gear 38. A dial 39 carriesa gear 40 which meshes with the gear 38. The dial 39 may carry any appropriate temperature marks or cooking instructions, as illustrated in con nection with the form of device shown in Fig. 5. A'spring 41 is providedto keep the dial under tension so that it will stay where placed.

When connecting the device I intend that the parts shall be in the position shown in on the bracket 34,.

Fig. 2 when the oven is heating upthat is,

out until'contact moves away from con- I tact 26 and, on further movement against through an opening in contact 23. This engagement of contacts 20 and 23 efi'ects the closure of a circuit which causes the heat to be turned off from the oven. The exact temperature at which this will take place can readily be controlled and adjusted by rotating dial 39.

The ordinary temperature range at which an oven is used is from 250 F. to 550 F., and this may be the range of temperatures controllable by dial 39, so that when the oven is not in use and cools down to room temperature a considerable movement of ele-.

ment 33 will take place. However by the arrangement which I provide this will place no load on the element 33 for it will simply move away from rod 31. Provision is also made totake care of another possible source of strain. Let us suppose that a very hot oven has been used so that sleeve 35 has been forced out to the limit of movement of dial 39, but element 33 has bent enough to move contact 20 away from contact 26. Suppose the operator now wishes to use theoven at a much lower tem eraturvnd so rotates dial 39 to draw bach sleeve'35. This exerts additional pressure on rod 31, but no harm results as arms 19 and 22 can both swing out against only the relatively light pressure exerted by sprin 21 and 24:.

The temperature range ldetween the time that contact 20 leaves contact 26 and the time that it meets contact 23which is substantially the fluctuationran e of the oven for any given settin of dia 39,can be controlled by adjusting the position of contact 23.

In Figs. 5, 6 and 7 a modified form of device is shown. The two forms are similar in principal and accordingly corresponding parts arev given like reference characters but with a prime added, and where the functions are identical the parts are not again described in detail. In this modified form it will be noted that push rod 3l'-is pivotally connected to the thermostatic element 33 and that instead of having a bearing corresponding to bearing)32, it passes freely ase 10. In order to hold rod 31 in place its outer end is re duced in size and this reduced portionslides in an appropriate 0 ning in arm 19.

The upper end 0 element 33' is riveted to a su port 35 which pivots on a bracket 34. T 's bracket likewise carries a threaded bearing 37 for the shaft 36' on the outer "endof which the dial 39 mounted. The

inner end of shaft 36 is adapted to bear against support 35 so that as dial 39 is rotated the lower end of element 33' can be forced towards base 10'.

In these views I likewise show the coverlate 42, and also the stop 43 carried by ial 39' which co-operates with indicator point 44 tolimit rotation of dial 39.

Figs. 4 and 5 show the way my device is installed on an oven. A portion ofthe outer wall 45 of theoven 46 is cut away so that the thermostatic element will be inside of the oven with base 10 against wall 45. This permits the thermostatic element to function properly, and at. the same time leaves the dial 39 readily accessible.

It is to be understood that the examples given are intended only as illustrations of we s in which my invention may be utilized an that many modifications may be made without departing from'the spirit of my invention.

What I claim is:

1. In a thermostatic control mechanism, the combination of a fixed contact, a movable contact spaced therefrom, a movable arm carrying a contact which lies between said spaced contacts, a thermostatic element pivotally mounted to swing, this element aving a portion which is movable to different positions as the element is exposed to different temperatures, means engaging the element to limit its swinging movement, means for adjusting the position of the limiting means, and a connection between the said movable portion of the element and the said arm.-

2. In a thermostatic control mechanism, the combination of a pair of contacts in spaced relation, an arm carrying a contact lying between the contacts, this arm being adapted to swing to bring its contact into enga ement with one or the other of the contacts rst mentioned, a thermostatic element pivotally mounted to swing and having a portion movable to different positions in accordance with temperature variations, adjustable means for limiting the swinging movement of the element, and a connection between the movable rtion of the element and the contact-carrying arm for transmitting the movement of the element due to temperature variations to the arm.

3. In a thermostatic control mechanism, the combination of a pair of contacts disposed in spaced relation, a swinging arm carrying a contact lying between the two spaced contacts, this arm being arranged to swing to brin its contact into enga ement with either 0 the said contacts, a t ermostatic element mounted to swing, this element having a portion movable to difierent positions in accordance with temperature variations, a rod connecting the movable portion of the element and the swinging arm and arranged to transmit the movement of the movable portion of the element resulting from temperature variations to the arm, and manually operable means for swinging the element on its ivot to alter the effect of movements of t e movable portion of the element upon the movable arm.

4. In a thermostatic control mechanism, the combination of a stationary contact, a movable arm carrying a contact spaced from the contact first mentioned, a second movable arm carrying a contact adapted to be brought into engagement with one or the other of the contacts first mentioned, a thermostatic element mounted to swing about a pivot, an operative connection between the second arm such that the arm is moved in accordance with the movement of the elc' ment due to temperature changes, and manually operable means for swinging the element on its pivot to vary the effectiveness of the connection.

5. In a thermostatic control mechanism,

' the combination of a stationary contact, a

movable'arm carrying a contact adapted to engage the stationary contact, a thermostatic element mounted to swing about a pivot, a rod adapted to transmit the movement of the element to the arm, and manually operable means for adjusting the element with reference to its pivot to vary the action of the element upon said rod.

6. In a thermostatic control mechanism, the combination of a stationary contact, a movable arm carrying a contact held normally in definite spaced relation to the contact first mentioned, a movable arm having a contact 1 ing between the stationary contact and t e contact on the first movable arm, this arm being arranged to permit its contact to engage with one or the other of the said contacts, and the two arms being arranged to swing in unison with their contacts engaged, a thermostatic element mounted to swing about a point, a rod connecting the element with the second movable arm, and manually operable means for moving the element with reference to its (pivotal point to vary its action upon the r0 means for transmitting the movement of the element due to temperature changes to the arm, and manually o erable means for varying the position of t 1e thermostat with reference to its pivotal point to vary its effect upon said transmitting means.

8. In a thermostatic control mechanism, the combination of a stationary contact, a movable arm, a contact on the arm adapted to be brought into engagement with the stationary contact, a thermostatic element adapted to swing about a pivotal point and having a portion movable to different positions in accordance with temperature changes, a rod adapted to transmit the movement of the movable portion of the element due to temperature changes to the arm, and manually o erable means for ad justing the position 0 the thermostatic element with reference to its pivotal point.

9.' In a thermostatic control mechanism,

the combination of a stationary contact, a

movable arm carrying a contact adapted to engage the stationary contact, a thermostatic element having one end pivotally mounted, this element having a portion movable to different positions as the element is exposed to temperature variations, a manually ad'usta'ble device for varying the position 0 the element with reference to its pivotal point, and a rod engaging the part of the element movable in accordance with temperature variations and transmitting such movements to the arm.

EDWARD L. FONSECA.

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