US2951929A

US2951929A - Heating apparatus

Info

Publication number: US2951929A
Application number: US826042A
Authority: US
Inventors: John J Fox
Original assignee: Westinghouse Electric Corp
Current assignee: CBS Corp
Priority date: 1959-07-09
Filing date: 1959-07-09
Publication date: 1960-09-06
Anticipated expiration: 1977-09-06

Description

Sept. 6, 1960 J. J. FOX

HEATING APPARATUS Filed July 9, 1959 N V E N TO R JO H N J. FOX

BYWY

ATTORNEY United States Patent HEATING APPARATUS John J. Fox, Lexington, Ohio, assignor to Westinghouse Electric Corporation, East Pittsburgh, Pa., 21 corporation of Pennsylvania Filed July 9, 1959, Ser. No. 826,042 2 Claims. Cl. 219-38) This invention relates to immersion heaters for mounting in an opening in the wall of a liquid heating vessel, and has for an object to provide an improved assembly for a heater of this type.

Another object of the invention is to provide rigid terminals in such heaters for electrical line connections.

Yet another object of the invention is the elimination, from immersion electrical heaters, of supporting terminal blocks for the terminal strips without sacrifice of rigidity of the strips.

In apparatus of this type, it is important to keep the assembly as compact and as simple as practical, both from the standpoint of acceptance by the customer and from the cost standpoint. To be acceptable to'the customer, the device must have approval of the Underwriters Laboratory. Where the terminal strips of immersion heater connections are unrestrained at their free ends, the Underwriters Laboratory requires materially greater spacing of the strips from each other and from the clamping plate than is required in constructions where the otherwise free ends of the strips are restrained. Hence, suitable restraining or anchoring of the free ends of the terminal strips may result in compactness or reduction in size of the assembly, provided the means relied upon for anchoring the free ends of the strips does not, in turn, complicate or enlarge the assembly.

The present invention effects suitable anchoring of the terminal strips at their otherwise free ends, without any additional parts or any enlargement of the assembly, and without reliance uponv insulating blocks or the like.

This is accomplished by providing the mounting plate with a central recess which receives the terminal portions of the tubular sheath of the resistance heater, filling the recess with a body of thermal setting insulating material which, when set, seals the sheath terminals, and forming the terminal strips in U-shape with one leg secured to a terminal pin of the heater and the free end of the other leg imbedded in the body of thermal setting material and thereby anchored against twistmg.

The foregoing and other objects are effected by the invention as will be apparent from the following description and claims taken in connection with the accompanying drawing, forming a part of this application, in which:

Fig. l is a perspective view of a heater assembly constructed in accordance with the present invention; and

Fig. 2 is a horizontal sectional view, taken along the line 11-11 of Fig. 1, looking in the direction indicated by the arrows.

The heater assembly shown in the drawing includes the usual tubular sheathed electrical resistance heater 11, having a helical resistance heating element 12 housed in a tubular sheath 13 and maintained spaced from the latter by suitable compacted insulating material 14 (Fig. 2). The heater 11 is carried by a mounting plate 16, centrally deformed to provide a recess 18 and a surrounding flat flange 19. The terminal portions of the 2,951,929 Patented Sept. 6, 1960 sheath 13 extend through appropriate openings in the bottom wall of the recess 18 and are disposed in the recess.

A clamping plate 21 is disposed in overlying relation to the flange 19 of the mounting plate 16 and has a central opening aligned with the recess 18 of the mounting plate. The electrical heating element 12 is provided with the usual terminal pins 22 projecting beyond the recess 18 and provided with terminal strips 23 of U-shape disposed in side-by-side, essentially parallel spaced relation. One leg 24 of each U-shaped terminal strip is permanently secured to a terminal pin 22 and the other leg 25 of each terminal strip has its free end extending into the recess 18.

A body of suitable thermal setting insulating material 26 is disposed in the recess 18 and is of suflicient depth to extend upwardly into the central opening of the clamping plate 21 to contact the walls of that opening, with the result that when the material 26 solidifies, it serves to hold together the clamping plate 21 and the mounting plate 16 and also to hermetically seal the open ends of the heater sheath 13. More particularly, the solidified thermal setting material 26 securely anchors the free ends of the legs 25 of the U-shaped terminal strips 23, so that the strips cannot be readily bent or moved relative to each other or to the clamping plate 21 when electrical connections are made thereto, as by tightening of lead connecting screws (not shown) received in the threaded openings 27 of the terminal strips 23.

Heating elements of this type must have minimum acceptable clearances between current carrying parts and adjacent metallic structure. Where the free ends of the terminal strips of such devices are not anchored, greater spacing of the two terminal strips with respect to each other and with respect to the adjacent clamping plate is required than is necessary where the free end portions of the strips are securely anchored. Accordingly, by anchoring such strips it is permissible to use closer spacing of the parts and consequently provide a smaller structure utilizing less material with consequent reduced cost. The present invention, as above described, provides this desirable anchor of the terminal strips without the use of the usual insulating blocks or corresponding anchoring means frequently utilized heretofore for this purpose.

The assembled mounting and clamping plates are provided with the usual corner bolt holes, for mounting of the assembly on a tank wall in the usual manner.

Summarizing, it will be apparent that by this invention, applicant utilizes a body of thermal setting insulating material disposed in a recess provided in the assembled structure to perform three essential functions: that is, to hermetically seal the ends of the heater sheath, to retain the clamping plate in predetermined relation with respect to the mounting plate, and to anchor the free ends of the terminal strips.

While the invention has been shown in but one form, it will be obvious to those skilled in the art that it is not so limited, but is susceptible of various changes and modifications without departing from the spirit thereof.

What is claimed is:

1. An electrical heater assembly comprising a tubular sheathed electrical resistance heater, a mounting plate for said heater, said mounting plate having a central recess and a surrounding flange, the tubular sheath of said heater having terminal portions extending through the mounting plate into the recess thereof, terminal pins for the resistance heater extending from the ends of said sheath, a clamping plate overlying the mounting plate flange and having a central opening therethrough overlying the mounting plate recess, a body of thermal setting insulating material filling the recess and covering the terminal portions of the tubular sheath, and U-shaped terminal strips each having one leg secured to one of the heater terminal pins and the other leg embedded in the body of thermal setting insulating material.

2. An electrical heater assembly comprising a tubular sheathed electrical resistance heater, a mounting plate for said heater, said mounting plate having a central recess and a surrounding flange, the tubular sheath of said heater having terminal portions extending through the mounting plate into the recess thereof, terminal pins for the resistance heater projecting beyond the ends of said sheath terminal portions, U-shaped terminal strips disposed in side-by-side essentially parallel spaced relation and each having one leg secured to a terminal pin 4 and the other leg terminating in the recess of the mounting plate, and a body of thermal setting insulating material disposed in said mounting plate recess, said material covering the terminal portions of the tubular sheath and anchoring said other legs of the U-shaped terminal strips.

References Cited in the file of this patent UNITED STATES PATENTS Boggs et al. Nov. 8, 1955 2,860,227 Fox Nov. 11, 1958 FOREIGN PATENTS 488,370 Great Britain July 5, 1938