US1902452A - Thermostatic switch - Google Patents

Description

March 21, R JOHNSON 1,902,452

THERMOSTATIC SWITCH Filed April 19, 192 5 Sheets-Sheet 1 March 21, 1933. R w JOHNSON 1,902,452

' THERMOSTATIC SWITCH Filed A ril- 19, 1929 s Sheets-Sheet 2 R. w. JOHNSON 1.902,452

THERMO STA TIC SWITCH March 21, 1933.

s Sheets-Sheet 3 Filed April 19, 1929 Patented Mar. 21, 1933 UNITED- STATES PATENT OFFICE ROY W. JOHNSON, OF MILWAUKEE, WISCONSIN, ASSIGNOR, IBY MESNE ASSIGNMENTS,

TO MINNEAPOLIS-HONEYWELL REGULATOR COMPANY, OF MINNEAPOLIS, MINNE- SOTA, A CORPORATION OF DELAWARE THERMOSTATIC SWITCH Application filer! April 19,

co-pending application of Roy W. J ohnson,

. executed under even date herewith, filed April 19, 1929, Serial Number 356,579, but is also equally well adapted for use in other systems in which it is desired to control electric circuits in accordance with the temperature of a certain environment.

Various types of thermostatically controlled electric switches of this character have been devised. Generally, such thermostati- ("ally controlled switches comprise a bi-metallic element or other type of thermostat which controls the operation of an electric switch in accordance with temperature variations. The switch consists of a pair of rela-' tively fixed opposed contacts between which a movable switch blade operates. The movable switch blade is usually directly and rigidly connected to the thermostat so that the thermostat causes the Switchblade to engage one or the other of the fixed contacts depending upon the temperature of the environment of the thermostat. The switch exercises such control over the heating plant or system with which it is organized as to maintain the temperature of the room or of the environment of the thermostat at a predetermined point.

Frequently it is desirable to vary the temperature that is to be maintained; as, for example, in household installations,.it is desirable to have a higher temperature during the 7 day than during certain hours of the night. To permit of such variable operation of the thermostatic swit-h it is necessary to have some form of adjustment operable to vary the point at which the thermostat will-effect switch operation.

Heretofore there have been two general forms or types of constructions for efiecting thisadjustment. In one type the thermostat has been provided with an adjustable mountin g for the thermostat so that the thermostat is adjusted bodily to vary the temperature at .the thermostat, will, in some adjustments, en-

as desired without subjecting the thermostatic element of the switch or any of its parts 1929. Serial No. 356,581.

which the thermostat effects switch operation. In the other type of construction the thermo stat has a fixed mounting on the base but the two relatively fixed contacts, which coact with the movable switch blade carried and controlled by the thermostat, are adjustably mounted on the base.

In either type of device heretofore known and used, the thermostatic element is at times subjected to excessive and sustained stress and strain which eventually lessens the efficiency and sensitivity of the device, and causes a disparity between the indicated temperature on the dial of the adjustment and the actual temperature at which the circuit is made or broken. This disadvantage results from the fact that, due to the nature of the adjustment provided, the movable switch blade, which is directly and rigidly connected to gage one or the other of the fixed contacts and tend to hold the thermostat against the expansion or contraction which must occur therein upon any considerable variation or difference between the temperature for which the device is set and the temperature to which the thermostat is subjected.

Moreover, where the types of thermostats heretofore known and used have been employed in household installations they are mounted on a wall of a room and are subject to considerable vibration which results in chattering or rebounding of the movable blade of the switch thereby producing sparking and causing a pitting of the contacts.

One of the principal objects of the present invention is to provide a thermostatic switch wherein the temperature at which the thermostat efiects switch operation may be varied to any material amount of strain or stress and in which the movable blade of the switch is held against chattering or vibratory movement even though the switch be subjected to considerable vibration.

Another important object of the invention resides in the provision of an automatic time control for a thermostatic switch of this nature which may be easily set to vary the tem- 1 perature at which the thermostat efiects switch operation during any desired period or interval. Thus, the time controlled means may be set to cause the thermostatic switch to maintain one temperature during the day will be hereinafter more fully described and particularly pointed out in the appended claims, reference being had to the accompanying drawings, forming a part of this specification, and in which:

Figure 1 is a view in front elevation of a time controlled thermostatic switch embodying the principles of the invention, the cover being removed and part of the thermostatically operated'arm being cut away to show the operation of the device;

Figure 2 is a view in rear elevation of the device of Figure 1 with the back plate re:

, moved and a control lever partly cutaway to show the operation of the parts;

Figure 3 is a view in central vertical cross section of the switch shown in Figure 1, parts being shownin elevation for the sake of illustration;

Figure 4: is a similar vertical cross sectional view showing a form of the invention which is not time controlled;

Figures 5, 6, 7 and 8 are diagrammatic views in elevation illustrating the novel operation of the thermostatic switch;

Figure 9 is a plan View of the gearing employed for driving the cams 0f the time controlled mechanism, the casing and clock being removed for the sake of illustration;

Figure 10 is a View partly in section on line 10 10 of Figure 9 but also showing the clock and its casing in elevation;

Figure 11 is a group view in perspective illustrating one of the cams and the parts associated therewith;

Figure 12 is a View in rear elevation showing another and preferred form of cam structure; c

Figure 13 is-a group view in perspective showing one of the cams of Figure '12 and the parts associated therewith;

'Figure 14 is a detail view partly in elevation and partly in section showing the assembly of the parts illustrated in Figure 13;

Figure 15 is a detail sectional view on line 15-15 of Figure 14;

Figure 16 shows a construction of thermo- Figure 17 is a fragmentary detail View showing parts of the switch illustrated in Figure 16, parts being shown in section for the sake of illustration.

In the embodiment of the invention shown in Figures 1 to 3, inclusive, the thermostatic switch is organized with a time controlled means which automatically varies the action of the thermostatic switch at selected intervals. In Figure "4: the same thermostatic switch is illustrated withoutthe time controlled means. 1 However, as the thermostatic switch is identical in both embodiments of the invention, a single description will serve for the thermostatic switch of both forms.

Referring to Figures 1 and 3 of the drawings, the numeral 1 designates a base on which a thermostat, designated generally at 7, and a switch mechanism, designated generally at 8, are mounted, the thermostat 7 and switch mechanism 8 being enclosed and housed by a cover 2 releasably secured to the base. The cover 2 may be secured to the base 1 by means of a flanged retaining strip 3 with which the flanged lower end of'the cover is releasably interfitted. A latch 4 is provided upon the upper end of the cover and coacts with the upper end of the base 1, as shown in Figure 3, to releasably hold the cover. in position.

The thermo-responsive element of the thermostat may be of usual construction and, as shown, consists of a bi-metallic spiral having its inner and upper end securely fastened to a mounting bracket 9.

The mounting bracket 9 is adjustably supported upon the base l by means of a combined pivot and lock screw 9' extending througha pivot opening in a flange of the bracket 9 and threaded into the base 1.

hen the screw 9 is tightened up it clamps tric 10 havinga frictional pivotal mounting on the base and having its eccentric portion or cam portion operating in a slot 11 formed in the lower end of the attaching flange of the bracket 9. The head of the cam 10 is formed with a screw slot 10', to facilitate adjustment thereof. When the mounting bracket has been set to position the thermostat properly it is seldom disturbed as it is in the nature of a permanent adjustment. v

The lower or outer end of the bi-metallic element is soldered or otherwise rigidly secured to the upper end of an operating arm 12, which extends downwardly. and has its lower end bent inwardly at right anglesand bifurcated to receive and opera-tively engage a pin 13 of the actuating means of the,

switch 8.

As shown to advantage in Figures 1, 3 and times.

prises two relatively fixed contacts 14 and 15, the contacts 14 and 15 being integral with the adjacent ends of adjusting screws 16 and 17 threaded through binding posts 18 and 19 which are secured to and project outwardly positioned and is designed and adapted so that its upper endis engaged with either one or the other of the contacts 14 and 15 at all Adjacent its lower end the blade 20 is provided with laterally extending knife edges 20 which engage knife edge bearings 22 formed in the lower portion of a contact carrier 22. The upper end of this contact carrier is pivotally supported and when the range of action of the thermostat is to be varied then the pivotal support is adjustable so that the contact carrier has an adjustable mounting on the base 1. It is this contact carrier 22 that has the pin 13 at its lower end engaged with and controlled by the slotted end of operating arm 12 of the thermostat. The movable switch blade 20 is biased to engage one or the other of the fixed contacts 14 and 15 by means of a. compression coil spring having its lower end fitted over a reduced extension of the upper end of a switch blade 20 and having its upper end fitted over a boss formed on an inturned portion or abutment 24 of the carrier 22.

.The direction in which the spring 25 biases the movable contact blade is determined by the position of the contact carrier 22 and the position of the contact carrier 22 is determined by the adjustment of its mounting and by the controlling action exerted upon it by the thermostat 7.

The adjustable mounting for the contact carrier 22 comprises a supporting pin 23 having its forward end pivotally connected to the upper end of the contact carrier 22, the intermediate portion ofthe pin extending through an arcuate slot 26 formed in the base plate 1 and the rearward end of the pin being fixed to the upper end of a rockable support which is preferably in the form of a lever 27. The lever 27 has a bearing collar 27 secured thereto and rotatably mounted on a fixed pin 28 secured to the base 1 and projecting rearwardly therefrom. To prevent axial displacement of the lever 27 and hold it in any position to which it may be adjusted, a friction washer 29 is mounted on the pin 28 and is forced into frictional engagement with the lever by a nut 30 threaded on the pin 28. The lower end of the lever 27 is provided with a forwardly extending horizontal handle portion 31 which projects through a slot 32 in the base to permit of manual adjustment of the lever. The handle portion 31 may be provided with a pointer 33 which passes over and coacts with a suitable temperature indicating scale 34 provided on the slotted retaining strip 3". v

Projections 35 are struck up from the base 1 to provide stops which limit the motion of the lower end of the carrier 22 thereby preventing the switch blade 20 from being brought into simultaneous engagement with both contacts 14 and 15. These projections are sufiiciently spaced, however, to permit free motion of the contact carrier 22 under the influence of the operating arm 12 of the thermostat for the full rangeof operation of the thermostat.

As shown in Figure 2, three binding posts 36, 37 and 38 are fastened to the base 1 and project rearwardly therefrom, the upper binding post 36 being electrically connected to the base, the two lower binding posts 37 and 38 being electrically insulated therefrom as by means of insulating washers 39 and insulating strips 39. The binding posts 37 and 38 are connected to the posts 18 and 19 respectively of the switch by means of conducting strips 40 which are insulated from the base by the insulating strips 39. As the binding post 36 is electrically connected to the base it is also electrically connected to the movable switch blade 20, through the thermostat and through the supporting-lever 27.

WVith the handle 31 set at the 7 0 mark on the scale, as shown in Figure 1, the switch blade 20 is engaged with the contact 14, as shown in Figure 5, as long as the temperature of the room or the environment of the thermostat is or more and this position of the switch will suspend the operation of the heating plant in accordance with the well known practice. The switch blade 20 is held engaged with the contact 14 by the spring 25 which, due to the position of the contact carrier 22, is slightly angled, as shown in Figure 5, and consequently tends to force the switch blade 20 to the left, as viewed in.

Figure 5. Assuming that the temperature of the room drops, the thermostat 7 will be contracted and will swing the operating arm 12 and rotate the contact carrier 22 in a clockwise direction, as viewed in Figure 5. about the supporting pin 23 as an axis and thereby rock the switch blade 20 about the contact 14, as a fulcrum, until angular relation with respect to the spring 25 is changed from that of Figure 5 to that of Figures 1 and 6. As a result, the spring causes the switch blade 20 to move with a snap action to the the spring 25 is such as to cause the spring to throw the switch blade over into engagement with the contactl i. As long as the adjustable mounting for the contact carrier 22 is left in any one setting the switch is controlled solely by the thermostat. The operation described would also obtain if the pin 23 were fixed to the base 1 as shown in my co-pending application for thermostatic switches for use with heaters filed under even date herewith. If, however, it is desired to have the switch operate at a different tem perature then the handle 31 is moved to rock the lever 27 and consequently to swing the pin 23 to the right or left accordingly as a higher or lower tem erature is desired. Such movement of the pm 23 swings the contact carrier 22 about the pin 13 and the slotted end of the operating arm 12 as a fulcrum. The contact carrier carries the sprin 25 with it and consequently varies the angu ar relation of the spring with respect to the switch blade 20 since the switch blade remains in substantially the same position during such movement of the carrier. For instance, if the thermostatic switch is set as shown in Figure 5 and it is desired to have a higher room temperature the handle 31 is swung over to the right or to registration with the scale marking 80', for example. This swings the contact carrier and the spring 25 from the position shown in Figure 5 to the position shown in Figure 8, and as the line of action of the spring 25 is changed it throws the contact blade 20 over into engagement with the contact 15 to start up the heating apparatus and thus cause the temperature of the room to be raised. -When the room temperature has reached the desired point the thermostat 7 has'been expanded to such extent as to swing the arm 12 to the position shown in Figure 7 which rocks the blade 20 about the contact 15 as a fulcrum and varies the angular relation between the blade 20 and the spring 25 to'such extent that the spring will throw the switch blade with a snap action into engagement with the contact 14. In other words, by moving the handle 31 over the scale 34 the angular position of the supporting pin 23 and of the contact carrier 22 is varied and consequently the angular relation of the axis of the spring 25 or of the line of. action of the spring and the blade is varied. It follows that the extent of motion of the operating arm 12 necessary to throw the axis of the spring 25 from one side to the other of the blade 20 is varied, and in thisway the device may be set to cause the desired operation at any predetermined tem perature.

This advantage of ready selection of a desired temperature is had without subjecting the thermostat to any distortion, stress or strain. In fact, the selection of the temperature at which the thermostat operates the switch is independent of the thermostat. The only force exerted on the thermostat is a small fraction of the horizontal component of'the force exerted on the blade 20 by the coil spring 25. j

In the form of the invention shown in Figures 1 to 3 and 9 to 12, inclusive, time controlled mechanism is organized with the thermostatic switch to automatically vary the action thereof duringpredetermined or selected intervals or periods. For example, this time controlled mechanism may be set to cause the thermostatic switch to maintain the room temperature at from six oclock in the morning until eleven oclock at night and at 55 from eleven oclock at night until six oclock in the morning. The organization is such as to permit of convenient variation of the periods or intervals as well as of the temperature that is maintained during the 'periods or intervals.

'In carrying out these purposes a clock or time-piece 5 is provided and is mounted on the base 1 below the cover 2. The. casing 5 of the clock is provided on its rear wall with a rearwardly extending stud 55 which, in the assembly, is so fitted in a socket 56 formed in or secured to the base 1 that the stud 55 may be freely rotated in its socket or may be freely withdrawn therefrom. A flanged boss 57 projects rearwardly from the casing 5 at a point spaced from the stud 55 and is cooperable with a hook 58 formed integral with the base 1 and projecting into the cutout or opening 1 formed in. the base behind the clock or time-piece 5. A flanged retaining strip 59 is also fastened to the rear wall of the clock casing 5 and its flange which is offset from the rear wall of the casing 5', is adapted to overlap a portion of the base 1 adjacent the opening 1. The flanged boss 57 and the flanged retaining strip 59 provide stops which properly position the clock and the parts carried thereby when they are engaged with the hook 58 and base respectively, as well as serve to securely hold the clock on the base against all movement except rotary movement about the stud 4 in. one direction. For preventing such rotary movement a latch 60 is pivoted on the base and is biased by a latch-spring 60' to engage one end of the retaining strip 59. The latch may be released by means of a finger button 61 connected to the latch and projecting exteriorly of the base. When the finger butbase 1 and hook 58 respectively, and this permits the stud 55 to be withdrawn from its socket 56 whereby the clockand the parts carried thereby are removed.

4 In general, the clock is utilized to drive two like cams 4 1 and 42 to cause these cams to operate at the proper time upon a follower 49 mounted in the lower end of a bell crank lever 50, pivoted as at 50' to'the base 1 and having its upper arm slotted as at 51 and receiving a pin 51 fixed to the rockable support or lever 27 and projecting rearwardly therefrom. The cams impart such movement to the lever 50 as to rock the lever 28 and the supporting pin .23 in such direction and to such extent as to vary the action of the thermostatic switch. Previously it has been explained how movement of the pin 23 shifts the contact carrier and varies the action of the thermostatic switch.

The novel features of the cams 41 and 42 and of their drive will now be described.

As shown in Figures 9 and 10, sleeve shafts 70 and 71 are rotatably mounted at the rear of thecock movement, the shaft 70 being rotatably fitted on a bushing 70 which is fixed to one of the frame plates of the clock movement and in which the winding stem 44' of the clock is loosely fitted. .The sleeve shaft 71 is rotatably mounted on a fixed pin 71 secured to one of the frame plates of the clock. For constraining the sleeve shafts 70 and 71 to rotate at the same rate of speed and in opposite directions twin gears 72 are provided, one said twin gear being fixed to each of the sleeve shafts and the two twin gears intermeshing as shown. One of the sleeve shafts is driven from'the clock movement by any suitable gearing which will cause the sleeve shafts to make one complete revolution every twenty-four hours. 1 As shown, such gearing inc .udes a drive pinion 73 which is appropriately actuated from the gear train of the clock movement and which meshes with a large gear wheel 7 4 fixed to the sleeve shaft 70. This gear wheel 74 also serves as a cycle indicator in that its upper face is colored black for half of its angular extent and white for the other half. A portion of the indicating face of the gear wheel 74 may be viewed through a slot 52 provided in the rear wall of the clock casing to indicate the cycle or period of operation. The clock isa so provided with a usual resetting stem 54 which operates on the elements of the gear train from which the sleeve shafts are driven and consequently whenever the clock is set by the stem 54 the sleeve shafts will be correspondingly moved. Usually, it is desirable to drive the pinion 73 from the gearing that-transmits the movement from the spring motor of the clock to the minute and hour hand shafts and the resetting stem is cooperable with this same gearing;

The cams 41 and 42. are mounted on the sleeve shafts and 71, respectively, foradjustment in two directions. As shown in Figures 9 and 11, the sleeve shafts 70 and 71 are of non-circular cross section in that they have flats 70 and 71*, and are-also formed with shoulders 77 adjacent their gear wheels 72. Indicating discs 45 and 46 are fitted on the sleeve shafts 7 Oand 71,-respectively, and are engaged with the shoulders 77 thereof, each disc having its central opening of the same form as that of the shaft whereby the discs are constrained to rotate with the shaft although slidable therealong. Each disc has a circumferential scale S applied thereto and occupying one half of the circumferential extent of the disc. The other half of each disc is providedwith a radial scale S. The circumferential scale S is made up of graduations and indicia designating time units such as hours and the radial scale S is made up of graduations and indicia designating degrees of temperature. The cams 41 and 42 are positioned on the shafts 70 and 71 and flat..y engage the graduated faces of their indi cating discs 45 and 46. The cams are of slotted formation and each has its one end pointed and its other end rounded. Adjacent the pointed end of each cam the slot thereof is of V-shape to provide a pointer or indicator 80 designed to ooact with the circumferential. scale S formed on its discs. The tail of each cam is rounded as at 81 and coacts with the radial scale S. Next applied on the shafts are washers 82 which also have their openings conforming in contour to the shape of the shaft so as to be constrained to rotate with theshaft, While slidable longitudinally thereof. Clamping nuts 83 are threaded on the outer ends of the shaft and act through coil springs 84 to force the washers 82 against the cams 41 and 42, the cams against the discs 45 and 46, and the discs against the shoulders 77 of the shafts 70 and 71 thereby clamping the cams in any adjustment. Split resilient washers 85 are snapped into annular grooves formed in the outer ends of the shafts 70 and 71 and provide releasable means preventing the nuts 83 from being backed entirely off of their shafts.

Whenever it is desirable to change the temperature at which the time controlled mechanism varies the action of the thermo-.

statically controlled switch the clock is removed by pressing in on the button 61 to release the latch 60 and then rotating the clock to disengage the headed stud 57 and the retaining strip 59 from the hook 58 and the base 1 respectively. The clock may be then entirely disengaged from the base and may be held so as to render the cams 41 and 42 readily accessible. By'backing off the nuts 83 the cams are released for appropriate circumferential and radial adjustment. In the embodiment shown, the cam 41 is designed to control the temperature that is to be maintained durin the day and to indicate its purpose and unction, the indicating disc associated therewith preferably has alight or white background with black scale markings and black indicia. Moreover, the clock casing around the disc 45 may bear the indicia Raises temperature. The cam 42 on the other hand controls the temperature that is to be maintained during certain tion which the cams impart to the follower 49 and consequently to determine the temperature at which thethermostat operates the switch following the coaction of either cam with the follower 49. In the adjustment shown in Figure 2, the cam 41 is set to so move the follower 49 at six oclock in the morning as to cause the thermostatic switch to maintain a room temperature at The cam 42 is set to so move the follower 49 as to cause the thermostatic switch to maintain a room temperature at 55 from eleven oclock at night until six oclock the following morning when the cam 41 again operates.

In Figures 12 to 15, inclusive, a slightly modified form of adjustable cam arrangement is provided. As in the other embodiment of the invention, sleeve shafts are prdvided and are identical in construction with the sleeve shafts 70 and 71 of the other form of the invention and like the sleeve shafts 70 and 71 are driven at the same rate of speed and in opposite directions and at such a rate that each sleeve shaft will make one com lete revolution every twenty-four hours. Xlso, as in the other form' of the invention indicating discs 45 and .46 are fitted on the sleeve shafts and are constrained to rotate therewith and have radial and circumferential scales such as S and S, respectively. The cam construction is, however, somewhat varied. The cams are designated at and 96 and each is of substantially disc-like form although having a tapered projection or nose designated at 95' and 96', respectively. The

cam discs have central openings of circular form and are slotted adjacent their noses so as to expose the circumferential scale of the disc which they overlie. The openings in the cam discs 95 and 96 are larger than the sleeve shafts and are designed toreceive eccentrics 97 which are formed on disc-like pointers 98 rotatably fitted on the sleeve, shafts. The disc-like pointers 98 have tapered projections 98 coacting with temperature scales T and T formed on the cams 95. and 96. With this arrangement when the disc-like pointers are rotated on their sleeve shafts and relative to the cams their eccentrics willshift the cams radially of the shafts and thereby vary the extentof movement which the cams will impart to. the followers. By providing interengaging serrations 99 on the cams and disc-like pointers, both of these parts may be adjusted simultaneously over the indicating discs'to vary the time at which the cams will engage the followers without varying the extent to which they move the follower. Aside from this variation in the cam arrangement the construction is otherwise the same as that of the embodiment first described and merely has a releasable means for clamping the cam to the indicator plate, such releasable means being in the form of a nut 83, spring 84, and washer 82, and also lock washer 85. However, the use of washers 82 and 85 are optional and either or both may be omitted if desired. The cam arrangement last described has the advantage of facilitating adjustment, especially as it permits of convenient variation of the time at which the cams will shift the follower without varying the extent of the shifting movement. But, of course, when it is desirable to vary the extent or amount of shifting movement this may conveniently be done as the inter-engaging serrations are readily releasable.

Figures 16 and 17 illustrate some slight variations in the structure of the thermostatic switch. In all substantial respects the construction is the same, the only difference being in the structure mounting of the movable contact blade 20 in the connections employed between the spring 25 and the blade 20 and carrier 22 and in the connection be- I tween the carrier 22 and the operating arm 12 of a thermostat. In lieu of providing knife edges on the contact blade and knife edge hearings on the carrier, the lower end of the carrier is bent around a pivot pin 20 which has its ends fitted in bearing openings formed in the carrier. At each end of the spring 25a flanged connector or cup 25 is formed, the body of the cup fitting into the spring and the flange engaging the end of the spring. The outer surface of the cup is formed with a tapered recess which engages asimilarly formed projection provided on the abutment of the carrier or on the contact depending upon the end of the spring at which the connector is located.

Instead of having a pin projecting downwardly from the carrier a laterally projecting headed pin 13 is provided and operates in a slot at the lower end of the operating arm of the thermostat. This construction avoids the necessity of inwardly bending the lower end of the arm 12. Except for these structural details the thermostatic switch of Figures 16 and 17 is identical with that first described and it operates in exactly the same manner.

The invention claimed is:

1, In an electric switch of the character described, the combination of a thermostat, a movable contact member, a spring acting upon said movable contact member and adapted to have varying angular relation with respect thereto to cause said contact member to move from one position to another with a snap action, and means operable in response to movement of said thermostat for varying said angular relation and also operable independently of said thermostat for varyingsaid angular relation to effect the temperature adjustment.

2. In an electric switch of the character described, the combination of a thermostat, a movable contact blade, a pivot for the blade, a spring for biasing the blade'to either of two positions, an abutment for the spring, and means operable in response to movement of the thermostat for moving the pivot and abutment to vary the direction and degree of the biasing action of the spring, and separate means operable independently of said thermostat for also moving the pivot and abutment to vary the direction and degree of the biasing action of the spring.

3. In a thermostatic switch, a movable contact member, a spring for biasing the same to either of two positions, shiftable means for varying the direction and degree of the biasing action of the spring, a thermostat connected to the shiftable means for operating the same and time controlled means connected to said shiftable means for shifting the same independently of the thermostat.

4. In a'thermostatic switch, a movable contact member, a spring for biasing the same to either of two positions, shiftable means for varying the direction and degree of the biasing action of the spring, a thermostat connected to the shiftable means for moving the same whereby to vary the bias of the spring and cause the movable blade to operate with a snap action under the influence of the thermostat and a manually adjustable device con nected to the shiftable means for moving the same independently of the thermostat.

5. In a time controlled switch, a fixed contact, a movable blade for engaging said contact, a pivot, a carrier mounted on the pivot and pivotally supportingsaid movable blade,

a thermostat coupled to said carrier for moving the same in accordance with temperature conditions, a spring coacting with the movable blade for yieldably holding the same in engagement with said contact until the carpair of fixed contacts mounted on said base, a'

carrier pivotally mounted on said base, a movable contact blade pivotally mounted on said carrier near its free end and disposedbetween said fixed contacts, the arrangement of carrier and blade being such that the blade extends from its pivot toward the pivot for the carrier, and a compression spring disposed between the free end of the blade, and said carrier having an abutment adjacent its pivot with whichthe spring is engaged, said spring causing the blade to move from one contact to the other with a snap action when the carrier is moved beyond alinement with the blade.

7. A thermostatic switch including a base, a pair. of fixed contacts mounted on the base, apivot, a carrier mounted on the pivot and having an abutment adjacent its pivoted end, a movable contact blade pivotally mounted near the free end of said carrier to cause movement of the blade in response to temperature conditions, and a spring interposed between the free end of said blade and said abutment for causing the blade to move with a snap action upon pivotal movement of the carrier. 7

8. A thermostatic switch including a fixed contact, a movable blade for engaging the contact,-a shiftable carrier pivotally supporting the blade and movable relative to the fixed contact, a spring bearing upon said blade to cause the same to move with a snap action when the carrier is shifted and a thermostat for shifting the carrier in response to temperature conditions.

9. A thermostatic switch including a pair switch including a base, a contact fixed to the base, a lever on the base having, a pivot fixed thereto, a carrier mounted on said pivot, a movable contact blade pivotally mounted on said carrier and adapted to engage said fixed contact, thermostatic means for moving the free end of said carrier and a spring bearing upon the blade to cause the same to move into 5 or out of engagement with'said fixed contact with a snap action.

11. A device of the character described comprising a base, a pair of oppositely disposed contacts mounted on the base, a swingable member pivoted to the base on one side of the axis of said contacts and having its movable end disposed on the opposite side of the axis of said contacts, a movable blade disposed between the opposing ends of the axially alined contacts'and pivoted to said swingable member adjacent its movable end, said swingable member having an abutment adjacent its pivoted end, and a spring interposed between the free end of the movable blade and said abutment.

12. A device of the character described comprising a base, a pair of oppositely disposed contacts mounted on the base, a movable carrier havin portions on opposite sides of the axis of said contacts, a movable blade pivoted to said carrier, and a spring acting between said movable blade and said carrier for causing snap action of the blade on movement of the carrier. 4 Y

13. A thermostatic switch comprising a pair of fixed contacts, a movable contact en gageable with either of the fixed contacts, a carrier on which said movable contact is fulcrumed, an adjustable mounting for one end of said carrier, a thermostat connected to the other end of said carrier, and a spring between the carrier and the movable contact and acting to bias the movable contact to engage one or the other of the fixed contacts depending upon the position to which the carrier is adjusted by the adjustable mounting and by the thermostat.

14. A thermostatic switch comprising a pair of relatively fixed contacts, a movable contact engageable with either ofthe fixed contacts, a carrier on which said movable contact is mounted, means for pivotally supporting said carrier, a spring between the carrier and the movable contact acting-to bias other of the relatively fixed contacts depending upon the angular relation of the carrier tothe fixed contacts, and thermo-responsive.

ing the same to engage or to disengage the fixed contact with a snap action depending 3 upon the angular relation between the spring the movable contact to engage one orthe' 16. In a thermostatic switch, a movable contact member, a spring for biasing the same to either of two positions, shiftable means for varying the direction and degree of the biasing action of the spring, a thermostat connected to the shiftable means for op erating the same, a time-piece, and an adjustable device connected to the time-piece and to the slliftable means independently of the thermostat for shifting the same from one position to another after a definite time interval.

17. In combination, a switch having a thermostat for operating the same, shiftable means for causing the thermostat to operate the switch at any selected one of a plurality of predetermined temperatures, a follower connected to the shiftablemeans for actuating the same, a time-piece, and two cams rotated in opposite directions by the time-piece and engageable with said follower for actuating the same and said shiftable means at preselected intervals.

18. A time controlled switch including a -movable contact member, means'for actuattime intervals, and a thermostat tor actuating said means in response to a change in temperature conditions.

19. A time controlled switch. including a movable contact member, thermostatically controlled means for actuating said member, a time-piece and a pair of rotating elements associated with said time-piece and driven thereby in opposite directions for operating said means at definite time intervals, at least one of said elements being adjustable to vary the time interval.

20. A thermostatically operable switch including a movable contact member, means for actuating saidmember, a thermostat for op erating said means in response to a change in temperature conditions, a time-piece and a pair of operating elements associated with saidtime-piece and driven thereby in opposite directions for operating said means at definite time intervals, at least one of said elements being adjust-able to vary the time interval and at least one of said elements being adjustable to vary the operation of the thermostat upon the movable contact to eifect temperature regulation.

21. In a thermostatic switch having a movable contact element, a thermostat for operating the element and a time-piece, the combination of mechanism for actuating said movable contact element, a cam driven by spect to the time said time-piece for operatin said mechanism, and means providing or the adjustment of said cam in one direction to vary the operation of the thermostat upon the movable contact to effect temperature regulation and also providing for the adjustment of said cam in another direction and with repiece to effect time regulation. I

22. A device of the character described comprising a thermostat, a switch controlled by the thermostat, means for varying the point at which the thermostat effects switch operation, and time controlled mechanism for operating said means and including a pair of oppositely driven rotatable elements and cams mounted on and driven by said elements, and adjustable radially and circumferentially thereof.

23. A device of the character described comprising a thermostat, a switch controlled by the thermostat, means for varying the point at which the thermostat effects switch operation, and t ime controlled mechanism for operating sa1d means and including a pair of oppositely driven shafts, indicators constrained to rotate with the shafts and bearing scales indicating time and temperature, cams adjustable over both scales of the indicators, and releasable means for securing the cams in position.

24. A device of the character described comprising a thermostat, a switch controlled by the thermostat, means for varying the point at which the thermostat efi'ects-switch operation, a cam follower connected to said means for actuating the same, a clock movement, a pair of shafts geared to the clock movement and to each other to be completely rotated in opposite directions once in every twenty-four. hours, cams mounted on said shafts. and cooperable with said follower, said cams being adjustable in two directions to vary the tlme at which they engage the follower and the extent of motion imparted thereto, and releasable means for securing the cams in any adjustment.

25. A device of the character described comprising a thermostat, a switch controlled by the thermostat, means for varying the point at which the thermostat effects switch operation, and time controlled mechamsm for operating said means and including a pair of oppositely driven rotatable elements, cams loosely mounted on said elements and adjustable circumferentially and transverse 1y with respect thereto, and releasable means for securing the cams to said elements 1n any adjustment.

26. A device of the character described comprising a thermostat, a switch controlled by the thermostat, means for varying the point at which the thermostat effects switch operation, and time controlled mechanism for operating said means and ncluding a pair of oppositelydriven rotatable elements, 'indicators constrained to rotate with said elements and bearing a scale indicating time, cams loosely fitted on said elements and adjustable circumferentially and transversely thereof, said cams having temperature indications on their exposed face, disc-like pointers rotatably mounted on said elements and having eccentric means interfitted with the cams for shifting the cams transversely upon relative rotary movement of the cams and disc-like pointers, and releasable means for securing the cams and pointers in any adjustment with respect to each other and with respect to said elements.

27. A device of the character described comprising a thermostat, a switch controlled by the thermostat, means for varying the point at which the thermostat effects switch operation, and time controlled mechanism for operating said means and including a pair of oppositely drivenrotatable elements, indicators constrained to rotate with said elements and bearing a scale indicating time, cams loosely fitted on said elements and adjustable circumferentially and transversely thereof, said cams having temperature indications on their exposed face, disc-like pointers rotatably mounted on said elements and having eccentric means interfitted with the cams for shifting the cams transversely upon relative rotary movement of the cams and disc-like pointers, and releasable means for securing the cams and pointers in any adjustment with respect to each other and with respect to said elements, said cams and said disc-like pointers having releasable engaging means whereby they may be simultaneously or independently adjusted circumferentially.

28. A device of the character described comprising a thermostat, a switch controlled by the thermostat, means for varying the point at which the thermostat effects switch operation, and time controlled mechanism for operating said means and including a pair of oppositely driven rotatable elements, i

cams loosely mounted on said elements and adjustable circumferentially and transversely with respect thereto, eccentrics rotatably mounted on said elements and coacting with the cams to adjust them transversely upon relative rotary movement between the ec centrics and cams, and releasable means for securing said cams, eccentrics and elements in any adjustment.

29. A device of the character described comprising a thermostat, a switch controlled by the thermostat, means for varying the point at which the thermostat efiects switch operation, and time controlled mechanism for operating said means and including a pair of oppositely driven rotatable elements, cams loosely mounted on said elements and adjustable circumferentially and transversely with respect thereto, means coacting with the camsto adjust them transversely upon relative motion of said means and said cams,

and releasable means for securing the cams in any adjustment.

30. In a time controlled thermostatic switch, a base, a clock, releasableinterfitting parts on the clock and base supporting the clock for rotative movement relative to and sliding movementitoward and away from the base, mter-engaging means on the clock and base for holding the clock against sliding movement relative to the base and against rotative movement in one direction, and a latch for holding the clock against rotative movement in the other direction.

In witness whereof, I hereto aflix my signature. ROY W. JOHNSON.

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