US3714395A

US3714395A - Electrical heating unit

Info

Publication number: US3714395A
Application number: US00106325A
Authority: US
Inventors: M Hummel
Original assignee: Acra Electric Corp
Current assignee: Acra Electric Corp
Priority date: 1971-01-14
Filing date: 1971-01-14
Publication date: 1973-01-30
Anticipated expiration: 1990-01-30

Abstract

The present invention relates generally to improvements in electrical heating units, and more particularly to improvements in electrical heating units of the type employing wafer-like material or sheets such as mica having an electrical heating coil associated therewith. The embodiment of the invention disclosed herein includes thin coplanar sheets of heat resistant, electrically non-conductive material such as mica, the outer peripheries of which in the aggregate generally define a circle. Diametral margins of said sheets are adjacently spaced and an electrical heating coil adjacently encircles said sheets. A terminal member is connected with each extremity of the coil, and suitable electrical insulating material adjacently superimposes opposite sides of the sheets. Means is provided for maintaining the sheets and insulating material in juxtaposition.

Description

United States Patent n91 Hummel 1 3,714,395 145] Jan. 30, 1973 [73] Assignee: Acra Electric Corporation, Schiller Park,lll.

[22] Filed: Jan. 14, 1971 [21] Appl. No.: 106,325

[52] U.S. Cl. ..2l9/544, 219/432, 219/433, 219/552, 338/301 [51] Int. Cl. ..H05b 3/44, 1105b 3/50 [58] Field of Search ..2l9/432, 433, 430, 436, 438, 219/345, 464, 458, 457, 544,218, 536, 552; 338/218, 286-288, 301, 299

[56] References Cited UNITED STATES PATENTS 957,226 5/1910 Logan ..338/30l X 1,170,169 2/1916 Kuhn et a1. ..2l9/433 X 2,448,388 8/1948 Plummer ..219/433 1,153,703 9/1915 Phelps ..338/301X 1,484,280 2/1924 Spahr ..338/30l X 2,568,465 9/1951 Scott ..338/2l8 X 2,570,975 9/1951 Osterheld ..219/462 X 2,605,382 7/1952 Kircher et a1 ..2l9/433 2,272,471 2/1942 Miller ..219/436 FOREIGN PATENTS OR APPLICATIONS 1,129,244 5/1962 Germany ..338/30l Primary ExaminerVolodymyr Y. Mayewsky Attorney-Olson, Trexler, Wolters & Bushnell 5 71 9 ABSTRACT The present invention relates generally to improvements in electrical heating units, and more particularly to improvements in electrical heating units of the type employing wafer-like material or sheets such as mica having an electrical heating coil associated therewith. The embodiment of the invention disclosed herein includes thin coplanar sheets of heat resistant, electrically non-conductive material such as mica, the outer peripheries of which in the aggregategenerally define a circle. Diametral margins of said sheets are adjacently spaced and an electrical heating coil adjacently encircles said sheets. A terminal member is connected with each extremity of the coil, and suitable electrical insulating material adjacently superimposes opposite sides of the sheets. Means is provided for maintaining the sheets and insulating material in juxtaposition.

1 Claim,.5 Drawing Figures Italy ..2l9/438 ELECTRICAL HEATING UNIT SUMMARY OF THE INVENTION One of the problems incident to the use of commercially available heating units such as heating units in the form of coils set in ceramic material, or heating elements enclosed within a ceramic tube, is that of maintaining uniform heat delivery to a hot plate or disc.

Another problem encountered when conventional heating units are employed in association with the hot plate for coffee containers and the like, is that of encountering short circuiting which results from heated liquid entering the area below the hot plate and contacting the heating coil.

It is an important object of the present invention to provide a compact, disc-like heating unit, which because of its structural design, will assure uniform heat delivery and which will preclude the above-mentioned problem of short circuiting.

Another object of the present invention is to provide the heating unit of the type set forth above which readily lends itself for use with normal 110 .volt supply, and by slight modification may be used with higher voltages such as those commonly available in European countries.

More specifically, the invention contemplates improvements in heating units of the type wherein a heating coil adjacently encircles a heat resistant electrically non-conductive material such as mica.

BRIEF DESCRIPTION OF THE DRAWING The foregoing and other objects and advantages will be more apparent from the following detailed description when considered in connection with the accompanying drawing wherein:

FIG. 1 is a vertical, sectional view of a heating unit constructed in accordance with the teachings of the present invention, said unit having in association therewith a conventional hot water or coffee container;

FIG. 2 is an exploded view of the constituent parts of the heating unit contemplated by the present invention;

FIG. 3 is an enlarged, horizontal, sectional view taken substantially along the line 3-3 of FIG. 4;

FIG. 4 is a fragmentary, enlarged, vertical sectional view taken substantially alongthe line 4--4 of FIG. 3; and, p

FIG. 5 is a fragmentary, vertical, transverse sectional view taken substantially along the line 5-5 of FIG. 3. i

A DESCRIPTION OF A'PREFERRED EMBODIMENT Referring now to the drawing more in detail, wherein like numerals have been employed to designate similar parts throughout the various figures, it will be seen that a heating unit designated generally by the numeral 10, is shown in operative association with a-stand 12 for supporting a conventional coffee container 14. The stand or base 12 is-provided with a well 16 for accommodating the heating'unit l0.

As will be seen from the exploded illustration in FIG. 2, the heating unit comprises a metallic hot plate 18, anelectrically insulating sheet or disc 20, a section 22 which includes coplanar sheets of

mica

24 and 26 having a heating coil 28 adjacently encircling said sheets, a second electrically insulating plate or disc 30, a metallic casing disc 32, and a sheet metal ring or collar 32, and is formed with a depending shank 38 adapted to accommodate a nut member 40 as shown in FIG. 1. An annular flange 42 of the disc member of the disc member 32 is adapted for clamping engagement with a complementary flange 44 of the ring 34. After the aforesaid constituent parts have been associated in the orderdescribed above, a flange 46 of the hot plate 18 may be bent radially inwardly so as to clamp the

flanges

42 and 44 together as clearly shown in FIG. 4.

Particular attention is directed to the shape and disposition of the heat

resistant sheet members

24 and 26. The peripheries of these sheets, in the aggregate,

substantially define a circle.

Dimetral margins

48 and 50 are adjacently spaced from each other as shown in FIGS. 2 and 3. Opposite extremities of the coil 28 are suitably connected with the

terminal members

52 and 54. Sections of the

terminal members

52 and 54 extend through

openings

52a and 54a respectively, in the metallic disc member 32, see FIGS. 2 and 5. Suitable insulating cement 56 may be employed to hold the terminals firmly within their respective apertures. Each of the

terminals

52 and 54 are electrically coupled with conductors 52b and 54b, respectively. Conventional plug and socket means 58 connects with the aforesaid electrical conductors 52b and 54b.

In instances where desired, the ring member 34 may be dispensed with and the flange 46 of the plate member 18 may be clamped directly against the flange 42. In such instances the shank member 36 may be dispensed with. Thus, the invention contemplates a heating unit of relatively thin compact form with or without the ring member 34.

From the foregoing it will be apparent that the present invention contemplates a very compact heating unit in which heat is uniformly distributed to the upper plate member. By employing heating coils wrapped around thin heat resistant sheets, such as sheets of mica, the peripheries of which in the aggregate substantially define a circle, heat will be uniformly and efficiently distributed to the disc-like hot plate. Also by crimping the margin of the hotplate, either directly against the flange 42, or alternatively against the flange 44, the electrical heating elements are sealed in position thereby precluding the association therewith of moisture which might cause short circuiting. The number of coil convolutions will be determined by the available voltage. Thus if the heating unit is to be used in the United States, spacing of the coil convolutions would be such as to enable the unit to be used with a volt source, whereas if the unit is to be used in other countries, as for example Europe, a larger number of coil convolutions would be employed to accommodate a 220 volt source. The heating unit contemplated by the present invention may be produced very economically. The compactness and simplicity of construction renders the heating unit useable in a wide range of applications and the unit is by no means limited for use as a heater for coffee containers.

I claim:

1. An electrical heating unit including thin coplanar sheets of heat-resistant, electrically nonconductive material such as mica, the outer peripheries of which in the aggregate generally define an arcuate contour, said plate adjacently underlying-saidv co-planar sheets, an annularly disposed mounting member for said unit depending from said second plate and provided with flange means clampingly impinged by the outer margin of said first plate.

Claims

1. An electrical heating unit including thin coplanar sheets of heat-resistant, electrically nonconductive material such as mica, the outer peripheries of which in the aggregate generally define an arcuate contour, said sheets having adjacently spaced diametral margins, an electrical conductor coil adjacently encircling said sheets, a terminal member connected with each extremity of said coil, heat resistant and electrically nonconductive insulating material adjacently superimposing opposite sides of said sheets, a heat conducting plate superimposing the co-planar sheets, a second plate adjacently underlying said coplanar sheets, an annularly disposed mounting member for said unit depending from said second plate and provided with flange means clampingly impinged by the outer margin of said first plate.