US2018220A - Electric circuit controlling thermometer - Google Patents

Description

Oct. 22, 1935. R. H. MORRISON ELECTRIC QIRCUIT CONTROLLING THERMOMETER Original Filed July l5, 1931 INVENTOR v E ROBE/w MMWR/50N v BY f %7 y L ORNEY Patented Oct. 22, 1935 PATENT OFFICE ELECTRIC CIRCUIT 'CONTROLLING THERMOMETER Robert H. Morrison, Morristown, N. J.

Original application July 15, 1931, Serial No. 551,013. Divided and this application May 29,

1933, Serial No. 673,376

iclaim. (01.201-4si 'I'his invention relates to electric circuit controlling devices and has for an object the thermostatically cutting in and out of the unitsY of a resistance coil located in the electrical circuit of the device thereby regulating the current flow value of the outward flow of electric current under the control of the various temperatures in the medium surrounding the device. In the preferred form of my invention the medium will act directly upon the bulb of the thermometer, preferably a mercurial thermometer.

One of the objects of the invention is to control the speed of an electric motor or similar device, by varying the electrical resistance in the l5 circuit by means of a. thermostatic device responsive to changes in temperature in the body or mass to which it is subjected.

Another object of the invention is to control an electrically operated device by means of a variable resistance coil controlled by a form of thermometer, the bulb of which is located in position to receive the influence of the heat 'or cold of some medium, as for instance air, the temperature of which it is desired to regulate or record.

Another object of my invention is to employ the column of a, mercurial thermometer for engaging electrical contacts. For the purpose of preventing amalgamation with the contacts 30 which are preferably made of metal, and the incidental fouling of such contacts, I prefer to float a neutral fluid on the top of the column to the end that the contact point is bathed in this neutral fluid at the time the contact is made between it and the mercury column and also at the time the contact is broken between it and such mercury column.

In the drawing accompanying this specification one practicable form of my invention is illustrated in which drawing:

Figure l shows the device in front elevation.

Fig. 2 is a front elevation, the face plate, seen in Fig. 1, having been removed.

45 Fig. 3 is a central longitudinal section of the device illustrated in Figs. 1 and 2, and

IFigmi is a vertical central section of the bulb and a portion of the column tube, showing what might be regarded as the normal surface of the 50 mercury in the bulb.

This invention is in part a division of my application, Serial No. 551,013, led by me July 15, 1931, which is to issue May 30, 1933, and bear number 1,912,154. The present invention relates 55 to the, thermometer for cutting in and out the units of a resistance coil. In my previous led and co-pending application the bulb of the thermometer was located in the water circulating system of the cooling device of an internal combustion engine. In the present illustration the 5 bulb of the thermometer is shown as being exposed to atmospheric air as its actuating medium, but it can be actuated by a fluid or mass.

In carrying out my invention, I employ a modified form of mercurial thermometer, it having 10 a bulb portion 5 and a column tube 6. The column tube 6 is shown as having a closed top as is customary in thermometers of this general type.

I find it preferable in most instances to make the tube of the thermometer rather heavier than l5 ordinary.

Within the bulb 5 is represented a body of mercury 'I which, under most idle temperatures of the instrument, is not sufficient to rise up into the column tube 6. What might be regarded as 20 the normal surface of the mercury in the bulb is represented at 8, (see Fig. 3). The body of mercury will be of suiiicient volume to rise up in the column tube 6 and form a column 9 at a predetermined temperature. For purposes presently to be described in detail a lighter neutral iluid IIJ is shown floating on top of the mercury of the column 9. A fluid which I have used for the fluid I0 in my thermometer is creosote which is neutral to the elements and conditions encountered, and is much lighter than mercury. Of course, there are other neutral light fluids which will perform 'the function and which are known to those skilled in the electric art.

A resistance unit is illustrated at I2 which is 35 connected by means of a number of lead wires I3 to contact points I4 located within the column tube and in position to be engaged by the column of mercury as it rises. The resistance herein illustrated is what is termed a sectionalized resistance 40 or a tapped resistance. Below the series of contacts connected to the coils of the resistance unit, there is located a contact I5 which is in position to be the rst to be contacted by the rising -column and the last to be uncovered by the falling column. A wire I6 is connected to this contact point I5, which is connected to a Wiring terminal I8, to which one of the circuit or leadin wires I9 is attached. The upper part ofthe resistance unit I2 is shown connected by means bo of a Wire 20, to the other wiring terminal and to the circuit.

The glass part of thethermometer is shown mounted in a rectangular box 34 open at the bottom 35 and having a. closed top 36. A block 31 u is shown secured to the back tt of the box. This block is hollowed out at the front for receiving the bulb 5 of the thermometer. A :rubber sleeve 39 preferably surrounds the bulb which is held firmly in position by a metal strip 4l). The upper end 4I on the column tube is shown somewhat enlarged and this is received by a suitably formed block 42 secured in the upper part of the box. A rubber cap 43 is shown enveloping the column end 4| and a metal strip 44 holds this part in position on the block 42.

An electric condenser represented at 22 is connected by means of a Wire 23 to the circuit wire 2D and by means of a wire 24 to the circuit wire I9 or to the wire terminal I8.

Of course, it is to be understood that the size and proportions of the various parts of the thermometer and the location of the contacts and the amount of the resist-ance unit and the capacity of the condenser will be regulated for the service to which the device is to be put.

The rise in temperature of the medium surrounding the thermometer or its bulb will have an influence upon the mercury 1 causing this to rise forcing before it the neutral liquid I0 and eventually reaching the rst contact I5, which closes the thermometer end of the electric circuit. At this point, however, there is no movement of electric current. A further rise in temperature and a further rise of the column 9 forces the liquid II past the various contacts I4, bathing them before their actual contact with the mercury of the column 9. Upon the contacting of the column of mercury S with the lowest of the contact points I4, the current passes from the source of the electrical energy, not shown, through the circuit including the entire resistance unit I2, through the lower lead I9, through the lower contact point I4, the mercury column 9, the point I5 to circuit. As the temperature continues to rise in the medium surrounding the thermometer bulb. the mercury column rises and contacts with one after another of the contact points I4, thereby cutting out in turn the various coils or elements until the entire resistance coil is cut out. ignated by the reference character 46. The circuit wire 20 is shown leading directly from the uppermost of the contact points I4.

A cover plate 50 is shown for protecting and screening portions of the device. The cover plate is preferably attached top and bottom to the box I4 and as being bent inwardly so that a central The uppermost o! these coils 1s desaoiaeeo longitudinal slot "5I reveals the column tube. which latter is shown projecting somewhat through the slot. 'While readings for the entire range of column movement may be placed on the tace of the plate 50 along the slot 5I, yet I prefer, if one is desired, to use only the 'temperature scale :for the range through which the column contact points are effective.

For reasons of economy in manufacture, due to various uses of devices, the number of contacts used in the column tube should be decreased or increased as required. .As one example; suppose the instrument is constructed to control the temperature of a household electric refrigerator. Due to various temperature ranges ln the many types that are now on the market in apartments, etc. they could not all be regulated the same. Some would require more contacts in the column tubethan others. A visible scale with the required range might be used in other types: That is, the device placed inside the refrigerator box, allowing a reading from outside, and so on.

Having thus described my invention, I claim and desire to secure by Letters Patent:

The combination with a thermometer having a. bulb, a column tube rising from the bulb and electrically conductive material in the bulb adapted to rise and fall as a column within the bore of the tube, connection terminals for the device, a plurality of contacts disposed along the tube within the bore thereof in positions to be serially contacted by the conductive material in its movements, the lowermost of such contacts being above the normal position of the top of the column when the thermometer is subjected to temperatures lower than those at which the device is intended to function, said conductor being connected to one terminal of the device, of a sectionalized resistance unit adapted to be connected to the circuit, lead wires connecting the elements of the resistance unit with the other of the said contacts, the lead wire from the upper of said contacts being connected to the other terminal of the device, the organization being such that the circuit is normally open and the mercury in the column is normally out of engagement with said lowermost contact, and when the instrument Ais in operation the main circuit passes thru the column of mercury from such lowermost contact to one or another ofthe other contacts, and a condenser connected across said terminals.

ROBERT H. MORRISON.

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