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Publication numberUS2104848 A
Publication typeGrant
Publication dateJan 11, 1938
Filing dateNov 11, 1935
Priority dateNov 11, 1935
Publication numberUS 2104848 A, US 2104848A, US-A-2104848, US2104848 A, US2104848A
InventorsClark Gordon H
Original AssigneeHoffman Gas & Electric Heater
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Electric switch
US 2104848 A
Abstract  available in
Previous page
Next page
Claims  available in
Description  (OCR text may contain errors)

Jan. 11, 1938. CLARK 2,104,848


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Jan. 11, 1938. "G. H. CLARK 2,104,848

ELECTRIC SWITCH Filed Nov. 11, 1955 2 Sheets-Sheet 2 I F/ci 5 9 T INVENTOR. Gofioa/v /z C'ZA/P/r Patented Jan. 11, 1938 UNITED STATES PATENT OFFICE 2,104,848 ELECTRIC swircn'.

Application November 11, 1935, Serial No. 49,242

3 Claims.

This invention relates to improvements in an electric switch having reference particularly to a thermostatically controlled switch for connecting and disconnecting the heating coil circuits in a two-coil system.

One of the objects of the invention is the provision of an eflicient double electric switch adapted to be actuated by a thermostat, particu- 'larly a thermostat of the tubular type, so as to close or open two electric circuits in succession when the temperature change affects the entire length of the thermostat, and to close or open one of said circuits only when the temperature change affects but one portion of the; thermostat. Other objects and features of novelty will appear as I proceed with the description of that embodiment of the invention which, for the purposes of the present application, I have illustrated in the accompanying drawings, in which Fig. 1 is an elevational view, partly broken away and partly in section, showing a water tank with my electrical heating means installed therein.

Fig. 2 is a diagram of the electric circuits.

Fig. 3 is a plan view of the double switch which .I employ in connection with the invention.

Fig. 4 is a side view of the same.

Fig. 5 is a transverse sectional view taken substantially on the line 5-5 of Fig. 4 showing the switch in position to connect the lower heating coil with its energizing circuit.

Fig. 6 is an end view' of the switch.

Fig. 7 is a longitudinal sectional view taken substantially on the line 1-1 of Fig. 3.

Fig. 8 is a bottom plan view taken substantially on the line 8--8 of Fig. 7, and

Fig. 9 is a detail view of one of the snap levers of the switch.

In Fig. 1 of the drawings there is illustrated a metallic water tank In, preferably in the-form of a vertical cylinder, which is surrounded by a cylindrical metallic casing H, spaced from the tank [9, with suitable insulation l2 interposed between the tank and the casing.

draw-off connection. Cold water is admitted to the tank l0 through an intake pipe l4 located near the bottom of the tank, while at the top of the tank there is a hot water delivery pipe l5. Inthe upper end of the tank 10 there is a central opening i6 in which there is mounted and welded a collar ii that forms a seat for metal plate l8. A gasket i9 is placed in the joint between this collar and plate, and the latter is fastened down by a series of studs 20.

5 On the. top of the casing N there is a flanged I3 is a valved metal cover 2| which has a circular'opening in the middle thereof. The inner edge of the cover 2| meets a cylindrical, preferably non-metallic, member 22 that surrounds the collar I1 and serves to confine that part of the insulation I2 5 which overlies the top of the tank 10. 23 is a metal disk with a depending annular rib 24 which extends down into the central opening in the cover 2!. The disk 23 is held in place by nuts on the upper ends of studs 25 which extend up- 10 wardly from the plate ill in which they are anchored. Finally, above the disk 23 there is a metallic cap 26 containing insulation 21 and having a bottom rim by means of which the cap is secured onto cover 2|.

The heating unit depends from and is supported by the plate E8, the latter serving also as a closure for the tank. In the present instance the heating unit is shown as comprising a tube 28,

preferably of copper, having a water-tight connection with theplate l8 and having a cap 29 at its lower end joined to the tube by a water-tight connection. Within the tube there is an upper heating coil 30 and a lower heating coil 3|, with electrical connections extending upwardly to the 25 top of the tube and into the space above plate l8.

The tube 28 is preferably located axially of the tank, that being the most efficient position for the heating coils. Alongside the tube 28, but spaced therefrom to permit free circulation of 30 water, there is a thermostat'32. While in some aspects of the invention the particular character of the thermostat is not of importanca'l prefer to utilize one of the type illustrated which consists of an outer tubular member 33 (see Fig. '7) 35 formed of metal having a high coefficient of expansion, and an inner rod 34 formed of metal having a low coeilicient of expansion. The tube 33 is preferably threaded into an opening in the plate l8, and the rod 34 projects upwardly through 40 and beyond that opening. The tube 33 and rod 34 are secured together at their lower ends. The thermostat is guided near its lower end in a bracket 35 which has a circular opening'therein to receive the thermostat loosely. The guide 45 bracket 35 serves to steady the/thermostat 32, and is especially useful on that account during transportation of the tank. It will be apparent that when the temperature of the water in the tank [0 rises the tube 33 will expand lengthwise, 50 causing the upper end of the rod 34 to descend, while cold water entering the tank will con tract the tube 33, thereby causing the rod 34 to rise. 7

It will be noted that the cold water intake pipe l4 terminates substantially beneath the lower end of thermostat 32, so that the introduction of cold water into the tank, as hot water is drawn out, affects the thermostat almost immediately.

Near the top of the tank outside the casing I I there is an electric junction box 85, from which conductors 31 and 38 extend inwardly to the control switch which is mounted on the plate l8 and which will now be described by reference to Figs. 3 to 8 inclusive in connection with the wiring diagram of Fig. 2.

The switch comprises a metallic frame member which consists of a base 88, an upright 48, and a shelf 4|, all integral. In the base there may be formed a pair of holes 42 for the reception of fastenings by means of which the switch is secured to the plate I8. The upright 48 about midway of its height is deformed to provide V-groove 43 which serves as a fulcrum for one end of an angular lever 44 that may be termed the operating lever. This lever has a knife edge at its inner end that seats in the V-groove 48. In the lever 44, spaced a short distance from its fulcrum, there is a threaded opening in which is received the threaded lower extremity of an adjusting post 45. This post has a socket in its lower end into which the upper extremity of thermostat rod 84 extends. The post 45 projects through a slot 48 in the shelf 4| and through a similar slot in a plate 41 which is secured to the upper surface of shelf 4| by a pair of shouldered studs 48, which have the additional function of stops for limiting the motion of a pointer 48 that is mounted on the upper end of the post. The pointer 48 also serves as a convenient means for grasping the post 45 in order to rotate it. It will be apparent that when the post 45 is turned down, the effective point of contact between the lever 44 and the rod 84 is lowered, while the turning of the post 45 in the opposite direction raises the effective pointof contact between the lever and the rod 34. In order to hold the lever 44 firmly against the rod 84 I provide a coil spring 50, the upper end of which engages the shelf 4|, and the lower end of which engages a washer 5| resting upon lever 44 surrounding the post 45.

On the outer extremity of lever 44 I mount, by means of screws 52 and 58, a triangular block 54 of insulating material, and in this block on either side of the lever holes are provided through which threaded pins 55 and 58 extend. On the upper ends of these pins there are nuts 51, by means of which the height of the pins may be ad justed. In practice they are adjusted to different heights, as indicated in Fig. 6, for a purpose which will presently appear.

A block of insulation 58 is secured to the base 88 by screws 58. On the inner ends of this block there are mounted two sheet metal conductor brackets and GI which are O-shaped in vertical section with their open sides facing each other. These brackets are held in place partly by two screws 62 and 53, and partly by shouldered insulation bushings 84 and that are held in position by bolts 88 and 81, the upper ends of which are provided with silver contact buttons 88 and 89 respectively. Contact buttons 18 and H are secured to the under sides of the top portions of the brackets 68 and 8|. From the lower arm of the bracket 8| there extends laterally an inz'tegral lip 12, in which is mounted a screw 18 for securing a wire conductor. 0n the opposite end of the block 58 there are mounted two separated metal plates 14 and I5. Above these plates there are thin spring metal plates 18 and. 11.

Sheet metal brackets 78 and 18 rest upon the plates 18 and I1 respectively. The parts 14, I8 and 18 are fastened together and to the block 58 by means of screws 88 and 8|. Similar fastenings for the parts l5, l1 and 18 are used, but not separately illustrated herein. The upright portions of the brackets 18 and 18 are bifurcated, and each of the bifurcations is deformed to provide a V-groove 82, all four of these grooves being in alignment. The thin metal plates 18 and 11 constitute the anchoring portions of two double leaf springs 88 and 84 which are curved upwardly and forwardly and have their forward portions secured to the upper sides of a pair of snap levers 85 and 88 respectively. The rear ends of these levers are bifurcated, as will appear particularly from Fig. 9, and the bifurcations are received in the V- grooves 82. They are held against sidewise movement largely by the springs 88 and 84, which are secured to the levers not only at the forward end of the latter but also at points near the rear ends of the bifurcations. Coil springs 81 and 88 are positioned in the bifurcations of the levers 85 and 88 respectively and extend between the bifurcations of the brackets 18 and 18, these springs having hooked forward ends that are received in holes in the levers and hooked rear ends that embrace reduced diameter portions on the lower ends of pins 55 and 58. At the forward ends of the levers there are double contact buttons 88 and 88 electrically and mechanically joined to the levers and to the leaf springs, and presenting good contact surfaces both above and beneath the levers. Integral lips 8| and 82 extend laterally from the plates I4 and 15 respectively, and have screws 88 and 84 respectively mounted therein, by means of which wire conductors may be secured, the current being carried through the leaf springs 88 and 84 to the levers 85 and 88 and the contact buttons 88 and 88.

In the under side of the insulation block 58 a diagonal groove is formed in which is positioned a metallic shunt strip or bar 88, which is secured .at its ends to the screw 82 and the bolt 81.

The rear ends of the coil springs 81 and 88 are positioned near the height of the fulcrums of levers 85 and 85. When the lever 44 is lowered by the expansion of thermostat tube 88, the rear ends of the springs 81 and 88 are lowered and the forward extremities of the levers 85 and 88 are drawn down upon their abutments or contact plates 68 and 88. As the tube 88 contracts how ever, raising the rod 84 and swinging the operating lever 44 upward, the rear ends of the springs 81 and 88 pass over or above the fulcrums of the levers 85 and 88, thereby snapping those levers into their upper positions, where they contact with the contact buttons 18 and I I. In the usual adjustment of the pins 55 and 88 this snap-over.

of the levers 85 and "takes place at different times in the movement of the thermostat. How ever, if it should be desired to make the two levers move simultaneously, this can be accomplished by positioning them at the same height in the insulation block 54;

Referring to Fig. 2, it will be seen that upper heating coil 88 is connected to conductor bracket 8| and contact button 'H through the lip I8 on the bracket, while the oppomte end of the coil is connected by a conductor 85 with line wire 81'. Lip 82 is connected with line wire 88, while lip 8| is connected by a conductor 88 with one end of the lower heating coil 8|, the opposite end of I Assuming that the tank is filled with cold water,

operating lever 44 of the switch will be in its raised position, due to the contraction of thermostat tube 33. Both snap levers and 86 will also be in their raised positions, or as indicated in Fig. 2, Where the buttons 89 and 90 are shown in contact with the buttons 10 and H. Current will then flow through the upper heating coil 30. This will continue until the heated water in the upper part of the tank has caused the t be 33 to expand sufiiciently to lower the operating lever 44 to such an extent as to snap lever 86 to its lower position, when the contact 90 will engage button 69 on bolt 61. The circuit through coil 30 will thereby be broken, and a circuit will be set up from line wire 38 through snap lever 86 to contact 69 and bolt 61, thence through shunt bar to screw 62, bracket 60 and contact button 10. Lever I5 being still in its upper position, current passes from button 10 to button 89 on the lever and thence through the. lever and spring 83 to plate 14 and lip 9 I, through conductor 96 to lower heating coil 3|, and through conductor 91 to line wire 31. The heating of the water in the lower part of the tank then continues until a predetermined temperature is reached, when the thermostat acts to lower lever 44 sufllciently to snap lever 85 to its lower position where it contacts with button 66, which is merely an insulated abutment. The circuit through the lower coil is thus broken.

In the event thatonly a small quantity of hot water is drawn from the tank, and a corresponding quantity of cold water is admitted beneath the thermostat, the latter will then raise the lever 44 a short distance suflicient to again snap lever 85 upwardly, returning it to contact with button 10. The circuit through lower heating coil 3| will therefore again be set up until the temperature is raised to the extent demanded by the thermostat, after which the'latter will act to disconnect coil 3I, as will be apparent.

Should the quantity of hot water withdrawn be considerable, the first effect will be to energize lower coil 3!, but this effect will be only temporary or until the cold water entering the tank has reduced thetemperature sufliciently to snap lever 86 also to its upper position, when coil 3| will be cut out and coil 30 will be cut in, whereupon the operation will be the same as above described for the condition where the current is turned on to heat a tank full of water.

In the ioreSOin description I have necessarily gone somewhat into detail in order to explain fully the particular embodiments of the invention herein illustrated, but I desire it to be understood that such detailed disclosures are not to be construed as amounting to limitations, except as they may be included in the appended claims.

Having thus described my invention, I claim:

1. In automatic control apparatus for a plurality of heating coils, a lever, thermostatic means for swinging the lever in response to temperature changes, a conductor lever for each heating coil, adjustable spring supports carried by said first named lever one for each of said coils, springs attached at their ends to said supports and said conductor levers adapted to hold said conductor levers in either on or off position, whereby the diflerent adjustments of said spring supports will cause said conductor levers to snap from one extreme position to the other extreme position either simultaneously or one at a time at predetermined points in a given movement of the thermostat in response to rising or falling temperature.

2. In an automatic control apparatus for a pair of heating coils, two conductor levers pivotally mounted with their pivots in alignment, two spring supports movable transversely across the line of said pivots, two springs each attached at one end to one of said supports and at the other end to one of said levers, whereby the springs are adapted to hold the levers in either of two extreme positions, an element movable transversely of said line of pivots, said element being adapted to be so moved by thermostatic means in response to temperature changes, and means for adjustably connecting said supports to said element, whereby the conductor levers will snap from one extreme position to the other one at a time at predetermined points in a .given movement of the thermostat in one direction.

3. In apparatus of the class described, means for moving an electric contact from operative to inoperative position and vice versa, comprising a lever, a coil spring on one side of said lever tending to hold it against movement in one direction, and a shaft extending through said spring threadably mounted in said lever and extending through the lever to form an abutment on the side opposite the spring for engagement with any suitable lever swinging element, whereby rotation of the shaft varies the adjustment of said abutment.


Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US2415522 *Sep 20, 1944Feb 11, 1947Mcgraw Electric CoThermal retarder
US2496889 *Feb 13, 1946Feb 7, 1950Gen Motors CorpSwitch for domestic appliances
US2666836 *Sep 5, 1950Jan 19, 1954Theodor StiebelElectric controller for heating elements
US2917617 *Apr 28, 1958Dec 15, 1959Henry Greubel AlfredHeating devices
US3257544 *May 9, 1963Jun 21, 1966Warren Electric CorpHeating circuits
US3265857 *Jan 2, 1963Aug 9, 1966Warren Electric CorpHeat exchanger for pre-heating fluids
US3419707 *Mar 7, 1966Dec 31, 1968Robertshaw Controls CoRod and tube temperature sensor for controlling the heating means of an oven or the like
US4347432 *Feb 26, 1981Aug 31, 1982E.G.O. Elektro-Gerate Blanc U. FischerGlass ceramic cooking appliance
US5293446 *May 28, 1991Mar 8, 1994Owens George GTwo stage thermostatically controlled electric water heating tank
US6432344Nov 4, 1998Aug 13, 2002Watlow Polymer TechnologyMethod of making an improved polymeric immersion heating element with skeletal support and optional heat transfer fins
US6519835Aug 18, 2000Feb 18, 2003Watlow Polymer TechnologiesMethod of formable thermoplastic laminate heated element assembly
US6541744Feb 12, 2001Apr 1, 2003Watlow Polymer TechnologiesPackaging having self-contained heater
US6748646Feb 21, 2002Jun 15, 2004Watlow Polymer TechnologiesMethod of manufacturing a molded heating element assembly
US20050098684 *Mar 14, 2003May 12, 2005Watlow Polymer TechnologiesPolymer-encapsulated heating elements for controlling the temperature of an aircraft compartment
DE1272421B *Jul 30, 1962Jul 11, 1968Walter Beck K GDruckabhaengiger zweipoliger elektrischer Schnappschalter
DE1665193B1 *Feb 19, 1968Aug 12, 1971Matsushita Electric Works LtdElektrischer Schnappschalter fuer Druckbetaetigung
U.S. Classification337/383, 392/451, 392/500, 337/390, 337/392
International ClassificationH01H37/60, H01H37/00
Cooperative ClassificationH01H37/60
European ClassificationH01H37/60