US 1273389 A
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Description (OCR text may contain errors)
W. D. LUDWICK.
ELECTRIC WATER HEATER.
APPLICATION FILED ocT.2I. I9I4.
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ELECTRIC WATER HEATER.
AFPLICATTON ETLED 0CT.2I, T914.
Batented July 23, MHS.
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Speeiacation of Letters cretenir Patented Italy 23, .idiot Application led @ctober 2, 19M. Serial No. temeon.
To cZZ 'Lo/"10m it mag/concern:
Be' it known that l, WAYNE D. linnn/16K, a citizen of :the United States,l residing near rlacoina, in 4the county oi Pierce, State of Washington, have invented certain new and useful improvements in Electric W ater-Heaters, oi which the following is a specification.
'lhis invention relates to devices for heating water by electric means and has .special reference to such devices as are adapted for domestic and similar uses. ylhe objects of my invention are to produce a device which will be of suiiicient electrical eiiiciency to enable it to enter into competition with water heaters in which a gaseous fuel is used as the heating agent; wiich is substantially indestructible; which is simple and cheap xto make; and which requires no career attention on the part of the user. l attain t/hese'and other objects by the devices and arrangements illustrated in the accompanying drawings, in whichl Figure 1 is a front elevation of Vmy device in use; Fig. 2 is a vertical section oi the central core thereof; Fig. 3 is a iront eleva.- tion ,of my device, parts thereoi3 being broken away to reveal the interior arrange` nient and construction; Fig. a is a `plan thereor", the upper plate having been removed; Fig. 5 is a cross-section oi the central core; Fig. 6 is a partial vertical section showing a diderent form of core; and Fig. l
1s a cross-section ,oi with such a core.
Similar numerals of reference refer to similar parts throughout t e several views.
Referring tothe drawings, the cold water is conducted by the pipe l to the lower orilce of the core 2. This core 2 is made of metallic and magnetic substance, such as iron or steel. This pipe l communicates witha distributing chamber V3 in the lower end of the core 2. A plurality of passages t lead upward from the chamber 3 to another similar chamber 5 at the upper end of the core. The water lis heated while passing through these passages .4.' The hot water is collected from the passages i in the chamber 5 and passes therefrom through the tank 7 or other container or pipe. 'lhe upper and lower orifices extend .eyond the casing of Lthe device so that the pipes l and 6 may be inserted therea heater constructed bodies il by in without disinounting theparts oi' the heater.
A primary coil 8, consisting of insulated wire/ot suitable qualities, .properly wound on a spool 9, entends entirely' around the core 2 in close contact therewith, and the terminals of said coil 8 are secured to the controlling switch (indicated at l0, through which it is connected to a proper Lsource of alternating current (not `.shown in the-drawings). A
The magnetic circuit comprises the said core 2 extending through the coil 8 and a pair of return circuits li, each ci which is built up oi a plurality of thin sheets of soit iron, said sheets secured .together and forniing a laminated body having high magnetic conductivity but of vsuch form as to be substantially free from eddy currents oit electricity. rlhe said magnetic bodies ll are formed so that their two ends engage the sides oi the core 2,'substantially in iine with the ends oi" the heating water passages l electric coil 8, thus forming a pair oi" continuous'magnetic loops passing through the center of the generating coil 8 and return ing outside thereof, said loops comprising a solid part within the coil and a larninated part outside thereof. v The bodies 1l must be kept in very close Contact with the core 2, for otherwise the magnetic resistance is largeiy increased by the gaps between the said parts. This may be accomplished Vby simply fastening the two means of straps to .the core 2, but prefer to clamp them together as "iol lows y'llhe outer corners orn the bodies .ll are'beveled as at l2. An upper and a lowercover or plate 1S are slipped over the ends of the core 2 and are provided with complementary beveled vinterior surfaces adapted to engage the beveled corners l2 of the parts therein, and pass therefrom outside of the 1l and to exert an inward thrust thereon.
',lension rodsid connect the two platesl and draw them toward each other. As these plates are thus the said bodies il laterally inward into timate contact with the core 2. @ne or" the plates 13 may be supported from vertical movement by a lug or' lugs 15 formed on the core, or by other ine-ans.
A casing 1 6 of suitable shape and x inaterial surrounds the parts 8 and il between the plates 13, being held thereby by means of the anges '17, as shown, and the controlling switch 10 may be mounted thereon.
Referring noW to 'the variation shown in Figs. 6 and 7 it'will be seen'thatthe core is f 23 inclose the distributing and collecting chambers at the ends of the core` 20. 1n this case the electric coil 24 maybe circular and thelaminated pieces 25 shaped to conform to the general shape of the device.
In the preferred form of the heater, the heating channel or core of the coil is an integral casting having a body of considerable area in cross section and is proportioned to secure the greatest heating effect due to hyteresis eddyv and secondary currents in the metal, while the fluid passage is of reduced cross section, with large surface area in proportion to its cross section area, whereby the whole body of water flowing through the heater is brought into intimate relation to the metalsurface. The core eX- tends beyond the ends of the coil and is provided with plane faces as shown in Fig. 2 to secure intimate contact of the ends of the laminated returns for the magnetic circuit and thereby reducemagnetic resistance.
In operation, the alternating current flowing in the coil causes rapid reversals in the magnetic condition of the core or heating duct and owing to eddy and secondary eurrents and hysteresis in the metal, rapid heating results. Owing to the employment of magnetic metal as the body of the heating duct and the provision of a returnl for the magnetic circuit, which return is practically without magnetic resistance, the heating effect is localized in the duct and the attenuated body of water is brought directly into contactlwith the heated metal.
To protect the coil, it may conveniently be wound on a spool of `heat insulating material, as indicated at 9, adapted to lit the heating duct, this construction being especially convenient for manufacturing economy.
.While there would be but slight loss in eiiiciency due to vconvection and radiation, such losses are largely prevented .by the casing which tightly incloses all of the parts and makes a compact and practically indestructible unit which may bev conveniently coupled in the ordinary piping systems now in use as a substitute. for or supplementagy to the usual gas water heater.
Having described my invention, what I claim is E 1. 1n an electric water heater, the combination-of 4a primarycoijl adapted to A conduct an alternating electric current; a neri-laminated magnetic core lcentrally .positioned Within said coil and'v adapted-'fito'wpermit the formation of secondary eddy currents therein; passages extending through said vcore' andadapted to hold the water ,to be .bodies are forced inward against said core;
and tension rods Vjoining said plates.
2. In an electric heater, the combination with a .duct formed of integral cast vmagnetizable metalof suiicient'cross sectional .area to properly conduct all the lines of force generated by the coil with. a cavity therein having lsmall cross sectional area in proportion to its walls, a coil surrounding the duct intermediate its ends, anda return for the magnetic circuit in contact with the duct at opposite ends of the coil, said return having less magnetic resistance than the duct and being substantially free from eddy currents, vwhereby heating is localized in the walls of the duct.
3. In an electric heater, the combination with a core of magnetizable material having a duct extending therethrough for thepassage of the material to be heated, saidv core being surrounded'by a magnet coil adapted to conduct an alternating current, and constituting the sole heating unit, and a return for the magnetic circuit in contact with the core at opposite ends of the coil, said return being of less magnetic lresistance than the core, wherebyvheating is localized.
in the walls of the duct.
`4c.. In an" electric heater, the combination with a duct formed of integral `cast: hysteretic magnetizable metal with a passage eX- tending therethrou 11 the cross sectional area o Athe passage being small ascompared with the cross sectional area of the -metal of than the duct and being substantially free-v the duct, a Ycoil for alternating, current surfrom eddy currents, whereby heating is localized in the walls o f the duct.
5. In an electric heater, the combination with a duct formed of integral hysteretic magnetizable metal with a passa-ge extending therethrough, the cross sectional area of vthe passage being small as compared with the cross sectional area of the metal of the duct, a coil for alternating current surrounding the duct intermediate its ends and a return for the magnetic circuit formed of a section of laminated magnetic metal in contact with the duct at opposite ends of the coil, whereby heating is localized in the Walls of the duct.
6. In an electric heater, the combination with a. substantially straight duct formed of integral hysteretic magnetizable metal with a passage extending therethrough, the cross sectional area of t-he passage being small as compared With the cross sectional area of the metal of the duct, a coil for alternating current surrounding the duct intermediate its ends, a'branehed return for the magnetic circuitformed of U-shaped sections of laminated magnetic metal with the ends of the sections in Contact with the duct above and below the coil, and means for separably retaining the elements in their assembled position.
7. In an electric heater for liquids, the comb-ination with a substantially straight duct formed of integral hysteretic magnetizable metal with plane exterior faces at the ends and a passage for the liquid extending through the duct, the cross sectional area of the passage being small as compared with the cross sectional area of the metal of the duct, a coil for alternating current surrounding the duct intermediate itsends, a return for the magnetic circuit formed of a U-shaped laminated metal section having plane faces at the ends, and means for clamping the plane faces of the duct and laminated met-al sections permanentlv together at points above and below the coil.
8. An electric heating apparatus, comprising a non-laminated magnetic core, a primary winding thereon; adapted to conduct an alternating electric current, said magnetic core having a distributing chamber at or near each end and a pluralit)Y of passages leading through said core and connecting said chambers, one or more laminated magnetic return circuits engaging said core at or near each end and forming a continuous magnetic circuit therewith around and through said coil.
9. In an electric heater, the combination of a primary coil adapted to conduct an alternating elec-tric current, an integral cast magnetizable core positioned Within said coil and adapted to permit the formation of eddy-currents and hysteresis therein, passages extending through said core and adapted to hold the material to be heated, the cross sectional area of each of the passages being small as compared with the area of their Walls; and laminated magnetic return circuits in Contact Wi th said core near the ends of said coil and passing outside of said coil.
WAYNE D. LUDWIcK. Witnesses