US1413887A - Incubator - Google Patents

Description

F. BABA.

INCUBATOR.

APPLICAHON FILED MAY 13. 1919.

1,41 3,887. Patented Apr. 25, 1922.

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INCUBATOR.

APPLICATION FILED MAY I3, 1910.

Patanted Apr. 25, 1922.

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@ALIGJMMQ UNITED STATES FRANZ BABA, OF IRVINGTON, NEW JERSEY.

INCUBATOR.

Application filed May 13,

To all whom it may concern Be it known that I, FRANZ BABA, citizen of Czecho-Slovakia, and resident of Irvington, in the county of Essex and State of New Jersey, have invented certain new and useful Improvements in Incubators, of which the following is a specification.

My invention relates to an incubator having an electric heating device and the object of the invention is to provide means to maintain the temperature within the oven accurately at the desired degree of tempera ture and to attain this end with as small an amount of electric current as possible.

For the illustration of my invention reference is had to the accompanying drawings, in which' i Fig. l is a front view of the oven, Fig. 2 and Fig. 3 are vertical sections of Fig. 1 along the lines aa and b-b, respectively; Fig. 4 is a horizontal section through the middle of Fig. .1 along line C-C; Fig. 5 is a plan section showing the heating element below the floor of the oven, Fig. 6 illustrates the heating element behind the rear wall of the oven. Figs. 7 and 8 illustrate the heating elements behind the left and right side walls respectively, of the oven; Fig. 9 is a plan which illustrates in a diagrammatical way the wiring system employing several circuits; Figs. 10 and 11 show in a diagrammatical way the arrangement to stretch the wires when. expanding by heat; Fig. 12 shows the oven having a thermostat attached to keepthe temperature permanently at a certain degree of heat, and Figs. 13, 14, 15, 16 and 17 show certain details of the construction of the thermostat which will be explained below.

Like numerals denote like parts throughout the several views, I am now going to describe by way of example one apparatus embodying my invention in which an inner boX 1, made of ceramic material, preferably porcelain, is inserted into an outer box 2 which may be of any material constituting a poor conductor of heat and electricity.

The cavity which naturally is left between the two boxes is closedin front by a frame 3, the inner box 1 being closed by a door 4, the outer box 2 by the door 5. Of the inner box 1 the bottom plate 6, the sidewalls 7 and 8 and the rear wall 9 are covered with asbestos plates 10, 11, 12 and 13, respectively, wire coils 14, 15, 16 and 17 being interposed between the respective wall and asbestos plate.

Specification of Letters Patent.

Patented Apr. 25, 1922 1919. Serial no. 296,849.

Each of the asbestos plates, 10, 11, 12 and 13 is cut in two, the smaller part being at tached to the bigger by means of a pair of side rails 18 and 18, made of a metal having a greater expansion coefiicient than the metal of-which the wire coils 14, 15, 16 and 17 are made. The wire coils are secured to the asbestos plates by means of binding posts,

for instance coil 17 to plate 13 by meansv of the posts 19 and 20. The coil 14 is attached to asbestos plate 10 by means of binding posts 21 and 22, the short connection between them being of such thick wire that there is no heating effect of the electric current in this part of the coil. The coil 15 is secured to asbestos plate 11 by means of binding posts 23 and coil 16 to asbestos plate 12 by means of posts 24. The electric current is supplied from the main 25 passing through the plug socket 26 and from there one branch 27 of the circuit passes directly into the coils, while the other 28 passes first through switch 29, then through condenser 30 and then through regulator 81.

The Figs. 5, 6, 7, and 8 show the asbestos plates detached from each other and unfolded; for a better understanding of the description it is assumed that the binding posts 20 and 21 are connected by wires 32 of such thickness as to exclude any heating effect. Following both branches 27 and 28 until one arrives at binding posts 19, one notices that the wire coil 17 provides for two parallel circuits each on each side of asbestos plate 13 and that by means of con necting wires 32 two parallel circuits each are provided in each half of the coil 14 on asbestos plate 10. On the other side there are only two parallel circuits provided by coil 15 and 16 on asbestos plates 11 and 12,

respectively; the wires 33 and 33 connect coil 17 with 15, wires 34:,and 34 coil 15 with 16, wires 35 and 35 connect coil 16 with 17 and thus complete the whole wiring system.

Fig. 12 is a vertical sectional view of the oven alon the line Z)-Z) of F i '1 corresponding to Fig. 4, but omittii the asbestos sheets and the wire coils shown in the latter figure. This Figure 12 shows the thermo static arrangement for automatically controlling the temperature in case same goes either beyond or below a certain degree.

To the outside of rear wall 9 a metal rod 36 it attached by means of a rivet 37 (see Figs. 12,14, 15 and 16) the rod 36 closely adjoining wall 9 and passing with its flat head 38 through a frame secured to the roof of base 1 by means of rivet 4.0, the upright arms -11 and 12 of frame 39, holding a pin 43 on which a bifurcated metal arm 4: 1 is fuicrumed, the outer ends of which are separated from each other by means of the link 115 made of insulating material, the outer part of arm 41 i being further provided with a binding post 16 and with a point M. The bifurcated end of arm 1 1 carries a plate 18 through which a screw 19 passes to rest with its point directly upon the flat head 38. The roof of box 1 is also provided with a plate 50 secured to box 1 by means of a rivet 51, the plate being titted with a binding post 52 and a metallic arm 53 ending in a point adapted to touch point 47 if arm 14: is suiliciently lowered. Socket is preferably mounted on top of the box 2 receiving the current from main 9.5 (see Fig. 4) and sending branch 27 of the circuit directly into coil 17 at the rear wall, the other branch 28 passing through switch 29 and from there through a condenser (not shown in Fig. 12, but indicated in Fig. 9) to plate 50, arms 53 and 4-7 forming part of branch 28, a wire connecting arm 4-? at binding post 46 with coil 17, the arrangement of which is shown in Fig. 9 and indicated on Fig. 12 as being located between the arrow heads of branch 27 and 28 in Fig. 12. The location of metal rod 36 and the relative position of the walls of boxes 1 and 2, the asbestos sheet and the heating coil 16 in the space between are illustrated in more detailed way by Figs. 16 and 17, both figures being a horizontal section through the rear wall 9 and rear wall of. box 2 at about the middle of Fig. 12.

The even is intended to be used as an incubator for medical,biological,chemical and similar scientific laboratories, as well as for household purposes.

As source of heat only electricity is considered and in connection herewith an important feature is immediately obvious from an inspection of the drawings for contrary to the usual way of mounting the wire over all the surface of the heating chamber only part of the outside surface of the chamber is covered with wire in my invention and certain zones are entirely withheld from the direct action of the electric current. The arrangement of the resistance wire around the outside of box 1 is made that there are free zones uncovered with wire; for instance the coil L1 below box 1 leaves of the space, in the rear, entirely uncovered with wire and provides same only for J, of the space at the right and left, so that of the middle is not covered with wires either.

The sides are covered with wire only to of their height, measured from the bottom to the top, and of the width measured from the front, so that of the space at the top and at the rear are not covered with wire.

The rear is covered with wire to only Z,- of its width and to of its height. In the middle there is a space left free from top to bottom, the space being approximately 5,} inch wide to receive the metal rod 36.

The top or roof of base 1 is not covered with any wiring at all, as material for the box 1 porcelain is preferred though any other ceramic or similar material may be applied, the surfaces of box 1, at least inside, being glazed, the wire can therefore be applied directly upon the outside wall of the box 1, an asbestos layer being put on to preserve the heat and concentrate same upon box 1.

The coils of resistance wire are prefer: bly as described in this present application, mounted on asbestos plates to be easily removed and put back again in case any of the coils fails to work for some cause or other. The interstice between coil and outer box 2 is either maintained as an air space acting as an insulator (a certain circulation taking place through holes in the bottom and top of box 2)or the interstice is filled up with a poor heat conductor, for instance with material like asbestos, glasswool, etc. The box 2 can be made from porcelain, asbestos, metal or wood, the material depending very much upon the degree of heat for which the oven is intended. The coils can be mounted that a plurality of circuits may be applied, two circuits being shown by way of example in the drawings; according to the desired temperature either one or more circuits are switched in.

The regulation of the heat of the oven is operated by means of a thermostat, metal rod 36 and the arm 1 1 mounted upon the roof of box 1 being parts of this particular outfit.

This new arrangement of the coils admits of an alisolutely even temperature within the inner sp cc of box 1 and offers the further advai'itage that the objects to be treated. within box 1 can never come into contact with the coils whereby a short circuit within the coils becomes a very remote possibility. The coil 14; reaches its current from coil 17, the binding posts 20 and 21 being actually united in the oven and the short connecting wires 32 between Figs. (3 and are only inserted for an easier understanding of the: description.

A. porcelain box to serve as box 1 is of particular advantage because it can easily be cleaned inside with warm water, or can be disinfected in any desired way because the coils are adjoining the. outside walls of box 1. As the inside box 1 of porcelain. also admits of treating materials of acid reaction the door 41 closing box 1, can then also be made of porcelain and can be titted as to have only porcelain parts touch each other,

all metal parts being then avoided inside box 1, the various-rivets mentioned above being for instance substituted by countersunk screw resting in a recess of the outside wall or box '1. As porcelain is a poor heat conductor and the coils of resistance wire closely adjoin box 1, a heat regulator of the type measuring and depending upon the temperature inside box 1 would not be of advantage, for the porcelain box 1 heats up slowly and before the heat would penetrate the walls of box 1 to reach the regulator inside of same, the temperature at; the inside walls of box 1 would be higher than desired before the inside regulator would switch oil the current; a further consequence would be that the temperatureeven after switching oli the current would still rise owing to the radiation of heat from the porcelain walls and if then the temperature sinks'again to the desired degree When the regulator is expected to automatically switch in again the electric current, then the temperature at the outside walls has fallen considerably lower than desirable. My invention has the purpose to attain an even heat within box 1 by means of arranging the wire coils as de scribed whereby the poor heat conductivity of the porcelainis turned to good advantage as the heat spreads more evenly already within and at the walls of the receiving box 1. My invention has the further purpose to provide the oven with a' most sensitive regulator which guarantees already by its close attachment to the porcelain box, having a small co-etficient of expansion, and by its own considerably greater .coeflicient or expansion, a quick and reliable eii'ect and thereby quick disconnections or connections of the circuit with the heating coils.

The metal rod 36, being the essential part of the thermostat, is closely joined to the wall of box 1 and receives its heat from said wall, the closely adjoining coils being covered with asbestos (see Fig. 16) to avoid the influencing of the accuracy 01 the regulator by heat radiating from the coils; the

metal rod 36 receiving heat from box 1, the rod will react upon the heating eilect in short intervals and as thus the heat o1 the porcelain box 1 is constantly measured or regulated, respectively, it stands to reason that the temperature inside the oven will soon be constant. Within the bifurcated arm 44 the set screw 49 serves automatically to maintain the desired temperature after same is reached once, all one has to do is to turn the screw until its lowest point reaches the flat head 38 of metalrod 36, which by the way is made of the expansionof' rod 86, the joint of points 47 and 5 1 is interrupted because rod 36 lifts screw 49 and armlt united therewith. Upon the slightest cooling off of rod 36 the electric circuit is reestablished because then brass upon' the arrangement shown in Figs. 10 and 11 where it is shown that to the asbestos sheet by binding posts 19 and slung around or through loops 56. Upon expansion of the wires, they hang loose and might admit of a short circuit, which is, l1OW8V61', aVOlCl6Cl as" the metal rails 18 and '18 have a greater coefficient of expansion than the wires and when expansion takes place owing to an increase in temperature, the rails expand more than the wires and thus keep the latter always straightened or the two parts of the asbestos plate are kept apart by springs 55 whereby the wires are also kept straight notwithstanding expansion owing to heat.

the wires are joined The operation of my ovenisabout as be sufficient the operator connects the upper terminal of branch circuit 27 with binding post 19 plus and the lower terminal of branch circuit 28 with binding post 19 (see Fig. 9) whereupon the other binding post 19 plus is connected by wire 33 to binding post 23 plus then by joining the outer branch of coil 15, the other end binding post 23 plus by means ofwire 34 to binding post 24-, thereby establishing connection with the inner branch of coil 16. The other end of coil 16 is joined to coil 17 by means of wire 85 at binding posts 24 and 19. As soon as the desired temperature is reached the set screw 49 is turned down until its lower end reaches flat head 38 of rod 36. If the temperature goes beyond the desired degree rod 36 will receive more heat from wall 9 and will expandsoas to lift arm 14 whereby the contact between points 54 and 47 will be interrupted and the flow of the electric current will cease as is obvious from a'study of Fig. 12. As soon as rod 36. has cooled down again to the proper temperature it will assume its original length again and naturally arm' l l will also sink into its original position thus re-establishing contact between points 53 and 47 whereupon the electric current will continue to flow and to exert its heating effect. It is obvious that thereby the walls of box 1 are continuously kept at the same temperature and that owing to the radiation of heat from the walls towards the center of box 1 the temperature must uniformly increase at all points of the chamber towards the desired degree and that there can be no variations after this degree is once obtained. Screw 49 could. be provided with a kind of a scale at its head which would indicate to the operator how far he has to turn down said screw to obtain any of the various temperatures he wants to obtain; likewise stem 53 could be arranged to have the form of a tube within which point 5a can slide up and down and a scale on this modified stem would accomplish the same result in regard to anticipating the effect of the thermostatic regulator.

What I claim is:

1. An incubator for producing a constant and'uniform temperature, comprising an inner box of material of low heat conductivity and being an insulator for electricity, an outer box surrounding said inner box and including an air space between both boxes, a system of resistance wires located within said air space and applied directly upon the outside of parts only of the bottom, sidewalls and rear side of said inner box, plates of low heat conductivity and being insulators for electricity covering said system of resistance wires, connections to pass the electric current through the system of resistance wires, and a thermostatic regulator controlling the flow of electric current, having its actuating members secured directly to the outside wall of the inner box.

2. An incubator for producing a constant and uniform temperature, comprising an inner box made of material of low heat conductivity and being an insulator for electricity, an outer box surrounding said inner box and inclosing an air space between both boxes, plates of low heat conductivity and being insulators for electricity covering the bottom, side walls and rear side of said inner box, a system of resistance wires mounted upon aforesaid plates being insulators for both heat and electricity and be ing adapted to extend in. length in proportion. to the extension of the coils of resistance wires caused by the flow of the electric current through them.

3. In an incubator of the character as described, the combination of insulating plates for both heat and electricity, said plates being divided in. two and held at their edges by metal rails having a greater expansion coel'licient than the metal from which the coils of resistance wires are made so as to stretch the latter when heated.

4. An incubator for producing a constant and uniform temperature, comprising an inner box of material of low heat conductivity and being an insulator for electricity, preferably porcelain, an outer box surrounding said inner box and inclosing an air space between said boxes, a system of resistance wires located within said air space and applied directly upon the outside wall of the inner box connections to pass the electric current through the system of resistance wires, a metallic element, capable of expanding and contracting owing to changes of temperature, secured to and heated by the outside wall of the inner box and adapted to interrupt and reestablish the flow of the electric current through the resistance wires.

5. An incubator for producing a constant and uniform temperature comprising an. inner box of material of low heat conductivity and being an insulator for electricity, preterably porcelain, an outer box of heat insulating material surrounding said inner box and inclosing an air space between said boxes, plates of heat insulating material covering the bottom and the sidewalls of the inner box removably arranged within said air space, a system of resistance wires mounted upon aforesaid heat insulating plates and held by same unto parts of the bottom and the sidewalls leaving certain zones of their surface and the top wall entirely free of such resistance wires, connections to pass the electric current through the system of resistance wires admitting of a plurality of circuits, a metallic element, capable of expanding and contracting owing to changes of temperature, secured to and heated by the outside wall of the inner box and adapted to interrupt and reestablish the flow of the electric current through the resistance Wires.

6. In an incubator of the character described, a metallic actuating member forming a part of the thermostatic regulator being secured to the outside of theinner box, the walls of said inner box being made of i nsulating material for both heat aud e]cctri ity secured to the outside wall of the box to be heated.

7. In the operation of an incubator as det-zcribed, the step of regulating the heat of the incubator by communicating the heat Off the walls made of material acting as an insulater for both heat and electricity, of the inner box to a metallic element secured to the outside wall of aforesaid inner box and adapted to actuate the other parts of the thermostatic regulator controlling the flow of the electric heating current.

Signed at Newark, in the county of Essex and State of New Jersey, this 10 day of May, A. D. 1919.

FRANZ BABA.

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