US1190061A - Thermostat. - Google Patents

Description

J. J. WOOD- THERMOSTAT. APPLICATION man JUNE 25. 1914.

Patented July 4, 1916.

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UNITED STATES PATENT OFFICE.

JAMES J. WOOD, 0F FORT WAYNE," INDIANA, ASSIGNOR T0 GENERAL ELECTRIC COM- IPAN'Y, A CORPORATION OF NEW YORK.

THnnMostrAr.

Specification of Letters Patent.

Patented July 4, 1916..

Application filed June 25, 1914. Serial No. 847,340.

To all whom it may concern:

Be it known that 1, JAMES J. Wooo, a citizen of the United States, residing at Fort Wayne, county of Allen, State of Indiana, have invented'certain new and useful 1mprovements in Thermostats, of which the following is a specification.

My invention relates to thermostats, and particularly to the improved construction and arrangement of the parts constituting such an instrument.

In instruments of this character, especially where they are designed to, operate on circuits of a considerable voltage, it is desirable that the opening and closing of the circuit should be positive and quick in order to prevent arcing at the contacts, and that the instrument should be sensitive and readily adjustable. v

My object has been, therefore, to produce an instrument which will operate in the manner outlined above, and at the same time will be compact, strong, accessible, and in member-distinct from but connected with the general an eflicientinstrument.

Another object of my invention'is to provide a thermostat having a movable contact thermostatic element and to provide a novel suspension for this member. v Still another object isto provide anti-friction .bearin'gs for the movable contact member mentioned above.

Further objects of my invention will appear from the detailed description and the claims appended thereto.

Briefly, my thermostat comprises a sup? porting plate carrying 'a centrally arranged stud. to which one end of a spirally coiled spring which constitutes a thermostatic element is connected. Over-lying this spring and oscillating across a vertical axis is aconv tact arm or bar pivoted at its lower end} on a stationary bearing. The free end of; the spring is pivotally connected to this bar just above the stationary bearing and when it contracts or expands, di1e to changes. in temperature, moves the barto one side. or the other of the vertical. 'The spring and stationarj bearing constitute a' suspension for the contact. bar. Preferably, the" contact bar is engagedby. one, of these hearings at two separated points and by the other at an intermediate point, thus forming a three point suspension, Bothof the elements. of

with the contact springs are stops limiting the movement of the contact arm. At the rear end of the stud which supports the thermostatic element, a worm and gear adjusting means is provided for adjusting the instrument so that it will operate at the desired temperature.

One of the many applications of my device is to refrigerating machines. an arrangement the contacts will be arranged to close a circuit to energize the coil of an electromagnetically operated switch when the contact arm moves to the left, for instance, and when it moves to the right will form a short circuit around this same coil, thereby taking care of the inductive kick.

I have, more fully described my invention In such g Figure 1 is a front elevation with the cover I removed; Fig.2 is a side elevation, looking at the left of Fig. 1, showing the. cover in section; Fig. 3 is a top view with the cover in section; Fig. 4 is a detail showing the Worm and gear adjusting means; and'Fig. 5

is a diagrammatic view showing the circuits when the thermostat is connected in the manner suggested above.

A supporting plate 10,- preferably lar, is supplied with legs ll by which it isintended that it shall be attached to a vertical surface. These legs are offset in such a way that the supporting'plate is held out from the surface to which" the instrument is applied, in order to accommodate certain parts projecting from the back of the plate.

It will be noted also that thesupporting legs project beyond the outer circumference of the plate, so that the instrument may be the plate a worm gear 14 is applied to this.

stud and secured by means of a nut 15. For

the purpose of adjusting this stud to any desired position, a worm 17 is supported by a stud 16 in operative relation with the gear 14. This worm is provided with a slotted head 18 projecting'beyond the outercircumference of the supporting plate, whereby it may be easily turned.

The forward end of the stud 12 is slotted to admit one end of'a thermostatic element formed as a spiral spring 20. This spring will respond to changes in temperature by expanding or contracting, and is preferably constructed in the usual manner out of two elements having different coefficients of expansion. As will be seen in Fig. 2, the outer end of the spring is reduced in width at 21 and provided with a slot 22 for a purpose to be later explained. This reduced end" is turned at practically right angles i with the main portion of the spring and is 20 sharpened to provide a knife edge for engagement w1th apivoted contact arm, as shown in dotted lines in Fig. 1. This contact blade or bar 30 is a U-shaped member whose central portion overlies the spring 20and whose legs 37 and 33 project inwardly above and below this spring. The lower leg 33 is provided with a'V-shaped groove on ts upper edge in which the sharpened edge of thespring 20 engages (see Fig. 1). Adjacent the ends of this leg are depending feet 34 providedwith an upwardly extending V-shaped groove. These grooved feet rest upon a stationary hearing in the form of a knife edge 32 held. in a stud 31 attached to the supporting plate. At approximately the center of the lower leg 33 a pin 35 is provided, which projects into the slot 22 .and prevents displacement of the end of the spring in the groove. The upper leg 3'1 is provided on its upper side, adjacent the end,

with a contact piece 38 which may be constructed of silver or any other non-corrosive conductor. 7

The pivoted contact arm 30 cooperates at its upper end with fixed contacts held in binding posts 40 and 40. The binding posts pass through apertures in the supporting plates 10 larger than the posts and are fixed in metal plates 41 suitably insulated from the plate 10 by means of pieces of insulation 42, the whole being held in position by means of insulated screws. Ad-

jacent their 'outer'ends, the binding posts 40 and 40 are slotted to receive spring con tact members 43, which are slitted, as will be seen from Figs. 2 and 3, and are provided .at the lower side of their free ends with contacts 44 which maybe constructed of silver or a similar metal. Supported upon the posts 40 and 40, at a point inside the spring contacts, are fixed stops 45 which venient point a third binding post 46 is electrically connected with the plate 10 and thereby, through the members 31 and 32, with the contact arm 30.

The instrument is preferably, provided with a cover 5 0 fitting in a groove 54 in the plate 10 and held in place by screws 51. This cover is provided with a transparentclosure 52. 4

The instrument may be applied to any device in which it is desired to open and close a circuit in response to changes in temperature. One manner of application is illustrated in Fig. 5. Here the mains 6O supply energy from a source of power (not shown). If the contact arm 30, electrically connected through the supporting plate with the binding post 46, is moved to the left until it touches the spring attached to binding post 40, then the operating coil 61 of an electromagnetically operated switch will be energized from the mains and the contacts 62, forming the terminals of any desired circuit, will be closed. Inthe preferred arrangementof my invention, the binding post 40 is connected to one terminal of the circuit which was closed, here one terminal of the coil 61, in such a manner that when the contact arm 30 touches the spring attached to the. binding post 40, the inductive portion of the circuit, here the coil 61,- isshort-circuited. Because of the particular arrangement of the parts, as later explained, the time interval between the opening of the circuit and the closing of the short circuit is very small, and any are which may be formed by the opening of the inductive circuit will be quickly extinguished. p I

It will be seen from an inspection of Fig. 1, that the contact arm frictionally engages thespring contacts 43 in such a way that some little pull is required to disengage the I the desired mean, before the arm 30 will be pulled over by the spring 20 from one spring contact 43 to the other, and that a considerable torque will have been thereby developed which will insure positive and quick action both in opening the short circuit and in energizing the other clrcuit. By means of the particular relations of the various elements, it will be seen that I am enabled to make my temperature responslve spring 20 of considerable width, and that as a result the torque developed thereby will be comparatively large. It should be further noted that the contact arm oscillates about a vertical plane through the knife edge 32,. and that, therefore, it cannot readily find a position of stable equilibrium between the two spring contacts. Further,

- the particular relation of the feet 34 and the reduced end 21 of the spring constitutes a three-point suspension for the contact arm, the points of engagement being provided with anti-friction bearings. By-means of the head 18 and the cooperating worm and gear, the stud 12 may be readily adjusted to any, desired position, thereby adjusting the tension of the spring so that it will respond to any desired temperature.

I conceive that various modifications of the details of the particular arrangement which I have shown. may be made, and I, accordingly, do not desire to be limited to the exact construction shown other than as I am limited by the terms of the appended claims, but I wish it understood that my invention extends not only to the broad gen-.

by Letters Patent of the United States, is,

1. A thermostatic switch comprising a movable contact bar having a leg extending at right angles thereto, a stationary support pivotally engaging with one side. of said leg, a coiled thermostatic element pivotally engaging with the opposed side of said leg, one of said coactingbearings engaging with said legat'two pointsand the other engaging at an intermediate point, and a fric- I tional contact", on each sidev of said contact 'bar to engage";- with and temporarily hold said contact bar. F

24A thermostat comprising a horizontal knifeedge support, a movable contact arm provided with a V -shaped groove resting upon said support and extending upwardly therefrom, said arm being provided with another V -shaped groove above the firstnamed groove, means responsive to changes in'temperature having a moving part resting in said uppergroovefand a fixed contact cotiperating with the upper end of said 3. thermostat comprising 'a flat supporting plate adapted to be arranged in a vertical plane, a knife-edge support perpenv stud and having its free end normally adjacent to and above said support a fixed contact, a movable contact arm cooperating therewith, saidfarm having an offset leg at 7 its lower end, said leg having a V-shaped groove in its upper side receiving the free end of said thermostatic element intermediate the ends of the'leg, feet adjacent the ends of said leg having a lI-shaped groove on their lower edges and bearing on said knife-edge support.

4. A thermostat comprising a flat supporting plate adapted to be arranged in a vertical plane, a contact arm pivoted to said plate at its lower end and arranged so that its upper end oscillates across a perpendicular axis through the pivot point, thermostatic means connected to said arm for moving the same, binding posts insulated from each. other and said arm attached to said plate on opposite sides of said axis adjacent the upper end of said arm, and contact springs carried by said posts curved to frictionally engage and temporarily retain said arm in contact therewith.

5. A thermostat comprising a flat supporting plate adapted tobearranged in a vertical plane, a contact arm pivoted to said plate at its lower end and arranged so that its upper end oscillates across a perpendicular axis through the pivot point, thermostatic means connected to said arm for mov-' ing the same, binding posts insulated from each other and said arm attached to said plate on opposite sides of said axis adjacent the upper end of said arm, contact springs carried by said posts curved to frictionallya vertical support, a substantially centrally arranged rotatable stud carried by said plate, a worm gear on said stud behind said plate, a worm for rotating saidgear, a spirally coiled spring in front of said plate having its inner end attached to said stud, a [Ll-shaped contact arm having its central portion overlying said spring in an approximately vertical position, means'for p1vot-.

ally supporting the lower leg of said contact arm at points adjacent its ends, said leg be- "ing provided with a V-shaped groove in its upper, side, the outer end of said spring being reduced in width and sharpened to en: gage said groove intermediate the ends of said leg, flexible contacts supported by but insulated from said plate at each side of and above'said spring and cooperating with the upper leg of said arm to frictionally engage the same, and stops adjacent said contacts.

7. A thermostatic switch comprising a movable contact bar having a leg extending at right angles thereto, a thermostatic ele-" menthaving a knife edge bearing upon the leg to move the contact bar, and a similar stationary bearing for the contact bar cooperating with the bearing of the thermo' static element to constitute a suspension for anti-friction bearing upon one oflset leg to set leg of the contact bar opposite said operate the same, a similar stationary bearbearings. I d 10 ing for the movable bar, one of said bear- In Witness whereof, I have hereunto set ings having two points of engagement, and my hand this 22nd day of June, 1914.

the other a single point between the two L JAMES J. WOOD. points, thereby forming a three-point sus Witnesses: pension for the bar, and one or more fixed H. E. CRANE,

contacts frictionally engaging with the ofi'- A. L. HADLEY.

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