US2369045A - Electric heating unit - Google Patents

Description

Fell 6, 1945" n... N. HAMPTON ETAL 2,369,045

ELECTRIC HEATING UNIT Original Filed Feb. 8, 1940 2 :o J4 n .LN HAMPTON /NVENTORSAH SHANGLE ATTORNEY Pa'tented @s md5 stars mais arcanes ancorato esamina leon N. Hampton, New Yorin. N. il., .irnos Shangle, Roselle, N. il., assignors to Te er phone Laboratories, incorporated, Ylorii. N. Y., a corporation oi New Yori;

Original application February il, 1940, Serial No. M7398, now Patent No. 2,274,408, elated Fehn rulary 2li, 1942. Divided and this .lannary ll, i942, Serial No. 4252?@ 2 Claims.

of a heat treated plastic material which has good lll electric insulating and good heat conducting characteristics. This core is formed with a plurality of means in the form of a cylindrical portion, a helically double threaded groove formed longitudinally thereof, a second cylindrical portion and a collar portion, with means in the form of terminals embedded in the collar portion dispOSed contiguous to the second cylindrical -portion for connecting with the resistance wire wound in the screw thread in the core and with lead-in Wires forming part of the heating unit.

Means' in the form ci a metallic sleeve closed at one end and constructed of a non-scaling alloy such as nicke1-si1ver serves as a housing for the resistance wire and the core with the annular space formed between the core and the sleeve lled with a plastic material similar to that of the core, such material adhesively uniting the core, the resistance wire and the nickel-silver sleeve into an homogeneous unit structure which has a high heat conductivity and a high dielectric characteristic.

lMeans in the form or a ceramic plug fitted into the open end of the sleeve serves for protecting the terminals embedded in the corel and the connecting ends of the resistance wire wound thereon while forming a closure at this end of the sleeve, the plug being provided with means for receiving a collar inwardly pressed from the sleeve for securing the plug in position in the sleeve, while the anchoring of the terminals in the core avoids the breaking of the resistance wire connected thereto upon a. pulling force applied to the lead-in wires connecting with the terminals.

Other novel features and advantages of the invention will appear from the following description and by the claims appended thereto reference being had to the accompanying drawing in which:

Fig. 1 ls an assembly view;

Fig. 2 is a longitudinal sectional view thereof;

Fig. 3 is a plain view oi' the core nais embedded therein i and the termll Fig. di is a cross-sectional view oi the core taken on line t-li of Fig. 3;

Fig. 5 is a left-end view; and

Fig. 6 is a cross-sectional view taken on line 6-6 of Fig. 2.

The heating element of the invention as shown in the drawing, consists of a core C best seen in Fig. 3, made as by molding and heat treating plastic material containing substantially 50 to 56 per cent ferro-silicate, 4e to 50 perucent Zircon and phosphoric acid as a binder. The core C is formed as by molding with a cylindrical portion 3i, a double threaded screw portion 3l, a second cylindrical portion SlYland a collar portion 32, Figs; 2, 3, Il, 5 and 6, into which 'wire terminals such as 33 and 3d are embedded. The cylindrical portion 3c is formed with a radially projecting lug 35 provided for anchoring the middle length portion of |.a helically 'coiled resistor wire 36 noninductively Wound in the double threaded screw portion 3l of the core, the resistance wire being made of a material known as kanthal" which comprises iron 67 per cent, chromium 25 per cent, aluminum 5 per cent, cobalt 3 per-cent.

The ends of the resistor wire 36 are passed through openings and into slots SL in the terminals 33 and 34 for connection at the periphery thereof and with the ends of lead-in conductors such as 3l and 38 tted into the terminals, the lead-in conductors 3l and 33 being made of an alloy of manganese and nickel and are secured to the terminals by pressing the :free ends of the latter over their respective conductors to form indentations as shown in Fig. 2. A sleeve 4D, Figs. l. 2 and 6, of a non-scaling material well known in the trade as nickel-silver, described in Metals Handbook, 1939 edition, closed at one end, serves as a casing for housing the core and the resistor wire 36 coiled thereon while the annular space formed by the sleeve 40 and the core is filled with a plastic material 39 of a composition consisting of substantially 50 per cent ferro-silicate, 50 per cent Zircon and phosphoric acid as a binder. This plastic material as used for the core and for lling the concentric space between the core and the metallic sleeve in the heating unit thus constructed when heat treated has been found to possess very nearly the dielectric property of phenol plastic and the thermal conductivity and hardness of cast iron while capable of resisting great temperature changes and adhering well with the preformed core thus forming a continuous heat path therebetween, the sleeve and the resistance wire, the notches nl, n2, n3 and n4 in the collar 32 being provided for pershown in Fig. 2 is provided with two diaxnetricaliy` parallelly disposed bores telescopically engaging the terminals Il and Il to which the conductors I1 and 3l and the ends of the resistance wire l.

` are connected. the bead Il being held securely therein by pressing a ridge r from the sleeve into a circular groove rl, formed at the periphery oi the bead.

Heating units constructed according to this invention have been found to possess s high degree o! emciency and long life in actual service.

What is claimed is:

l. In an electrical heating unit, a core or a molded heat-hardened material consisting of 50 per cent silicon, 50 per cent zircon and phosphoric acid as a binder, a resistance wire coiled thereon, a metallic sleeve of a copper-nickel-zinc alloy housing said core Aand said wire. and a heathardened material consisting of 50 per cent silicon, 50 per cent zircon and phosphoric acid as a binder filling the concentric space between said core and said sleeve and adhesively uniting said core, said wire and said metallic sleeve.

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2. An electric heating unit comprising a molded core made of a heat-hardened plastic material. said core comprising a cylindrical portion having a radial projection, a double helical screw thread portion, a second cylindrical portion and A a collar portion, a pair of diametrically` opposite terminals embedded in said collar portion in paraliel relation to each other and in parallel rela- 20 ductors, a metallic sleeve housing said core and said wire, and a heat-hardened plastic material iilling the concentric space between said lcore and said sleeve and adhesively uniting the whole to form a continuous heat path, the heat-hard- 25 ened material for said core and said filling consisting of 50 per cent silicon, 50 per cent zircon and phosphoric acid as a binder.

LEON N. HAMPTON. AMOS H. BHANGLE.

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