US778913A - Rheostat for electric-arc lamps. - Google Patents

Description

PATENTED JAN. 3, 1905,

B. A. STOWE. RHEOSTAT FOR ELECTRIC ARC LAMPS.

APPLICATION FILED OUT. 28. 1903.

2 SHEETii-SHEET l.

PATENTBD JAN. 3, 1905.

B. A. STOWE.

RHEOSTAT FOR ELECTRIC ARC LAMPS.

APPLIUATION FILED OCT. 28. 1903.

2 SHEETS-SHEET 2.,

/ N VE N TOR At/orney C UNITED STATES BERNARD A. STOWE, OF CLEVELAND, OHIO, ASSIGNOR TO THE JANDUS Patented January 3, 1905.

PATENT OFFICE.

ELECTRIC CO., OF CLEVELAND, OHIO.

RHEOSTAT FOR ELECTRIC-ARC LAMPS.

SPECIFICATION forming part of Letters Patent No. 778,913, dated January 3, 1905.

I Application filed October 28, 1903. Serial No. 178,926.

To a whom it may concern:

Be it known that I, BERNARD A. STowE, a resident of Cleveland, in the county of Cuyahoga and State of Ohio, have invented certain new and useful Improvements in Rheostats for Electric-Arc Lamps; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

My invention relates to improvements in electric-arc lamps, and more particularly to the construction and arrangement of the resistance device and its support, one object of the invention being to so construct the same as to permit of its ready insertion into and removal from the lamp structure without altering or removing any part of the latter.

A further object is to so construct a resistance-coil as to minimize the extent of bearing-surface thereof against its support to facilitate ventilation of the coil.

A further object is to so construct a resistance-coil and its support as to insure adequate ventilation of the coil.

With these objects in view the invention consists in certain novel features of construction and combinations and arrangements of parts, as hereinafter set forth, and pointed out in the claims.

In the accompanying drawings, Figure 1 is a sectional View of a lamp frame and easing, showing my improvements therein. Figs. 2, 3, and 4 are enlarged detail views.

The main shell orbody 1 of the lamp-casing consists of a single piece of sheet metal, which is corrugated between special corrugatingrolls, said corrugations being confined to the intermediate portion of the sheet. The operation of corrugating in this manner results in producing a cylindrical shell, inasmuch as the corrugations do. not extend the full width of the plate. The metal in the intermediate portion of the plate is crimped and the stock gathered, so as to cause the sheet to assume a cylindrical shape, the length of the uncorrugated portions determining the circumference of the enlarged portions of the shell and the depth of the corrugations determining the circumference,and consequently the diameter, of the corrugated or intermediate portion of the shell. The depths of the corrugations are graduated at the ends of the main corrugations, so as to produce a gradual change in the diameter intermediate between the small and large diameters of the shell. The enlarged lower portion of the shell is subsequently crimped, so as to decrease the diameter at the lower end of the edge of the shell, producing thereby a turning in of the shell which is utilized in the completed casings as a shield or screen 2 for preventing the ingress of water through the ventilating-holes 3 in a cast-iron ring 4, which constitutes an important member of the casing. The overlapping edges of the cylindrical shell are then secured by rivets, soldered or otherwise, and annular grooves or corrugations 5, rolled in the enlarged upper portion of the casing for the purpose of strengthening the same. A cap or hood 6 is disposed over the upper enlarged end of the shell and provided with aperipheral flange 7, preferably curved transversely. This curved flange projects outwardly from the shell and acts as a watershed and also to preclude an entrance of dust, rain, and dirt into the casing through the ventilating-holes 8. The lower enlarged portion of the casing is provided with an annular groove 9, which engages the cast-iron ring at and secured thereto by warping the shell to said cast-iron ring just previous to riveting or soldering the shell. The cast-iron ring at is provided with ventilating-holes 10 and supports from its inner periphery a plain cylindrical shell 11. The method of securing the shell 11 to the cast-iron ring is as follows:

The shell 11 primarily is rolled into cylindrical shape and the edges secured by the well-known form of lock-seam. An annular bead 12 is then rolled on the shell at a distance from the upper edge greater than the thickness of the cast-iron ring. The shell is then inserted into the ring, seated against the annular head 12, and the stock projecting above the cast-iron ring swaged or turned over, and the two parts thereby secured together. The shell 11 has secured to its lower end, by means of rivets or otherwise, a shallow stamping 13, of sheet metal, to which the outer globe-supporting device 1 1 is attached.

The floor-plate 15 of the lamp (which is supported by the central tube 16 of the lamp) is provided with an annular raised portion 17 integral therewith and presenting an inclined surface facing outwardly and which constitutes a surface of revolution of a truncated cone. Two bosses 18 are provided at diametrically opposite points and project from the upper surface of the iron ring l. These bosses are drilled and threaded radially and carry two screws 19, which project radially through and from the casing. The outer ends of these screws are provided with roughened heads 20 for convenience in operating the same. The screws 19 are located in such position relative to the case that when the latter is raised to its normal seat within the lamp-hood 6 they will be in such position as to engage the inclined surface forming a part of the floor-plate and which when screwed in results in forcing the case upwardly with considerable pressure against its seat in the hood, and thus preventing relative movement between the casing and the parts of the lamp structure with which it may be in contact. it is simply necessary to unscrew the two screws a suflicient distance to permit their ends to disengage the inclined surface and the projecting ledge of the floor-plate casting. A block 21 is located within and secured to the hood, and the central portion of this block is provided with an internally-threaded enlargement for the reception of the threaded upper end of carbon tube 16. This tube constitutes the spine of the lamp-frame, and around its upper portion the resistance-wire 22 and its support 23 are located.

The frame or support23 for the resistancecoil consists of a series of internally-grooved segments of porcelain, which when assembled make a complete ring having a series of circumferential grooves 24: for the reception of the resistance-coil. Each segment is made with slots in the bases of the grooves for ventilating purposes, and the structure of each segment is strengthened by integral cross-bars 25. The ridges between the grooves are notched, as at 26, to permit the resistance-coil to pass from one groove to another, and suitable provision is also made (such as perforated seats 27) for the attachment of binding-posts. The

To remove the casing,

resistance-coil is so constructed as to minimize the extent of its contact with the support, so as to insure the greatest possible facility for ventilation. The resistance-coil is therefore formed irregularly, so as to present the appearance of a spiral groove 28, extending from end to end thereof, said groove forming a continuous air-duct and permitting the coil to bear only at intervals against the segmental support. The segmental porcelain support for the resistance-coil is located in the enlarged upper portion of the shell or casing, and each segment is disposed upon a plate 29, and said plates are secured in turn to the hood 6 by means of bolts 30. By removing these bolts the segmental support will be released, and then by removing the resistance-coil the segments can be separated and removed from the lamp without disturbing the backbone or carbon-tube 16 or any part of the lamp structure.

Having fully described my invention, what I claim as new, and desire to secure by Letters Patent, is

1. The combination of a support consisting of several removable segments having alining grooves, and a resistance mounted removably in said grooves.

2. A resistance device comprising a sectional, annular support of insulating material having a groove therein, and a coil of resistanee-wire removably mounted in said groove, said coil having depressions to reduce the contacting portions of the coil with the support.

8. A resistance device, comprising a segmental support consisting of segments of insulating material cooperating to form a ring having peripheral grooves, and a coil of resistance-wire mounted in said grooves.

4. A resistance device comprising several separable porcelain segments cooperating to form a ring, said segments having alining grooves and having slots in the bottoms of said grooves, a resistance-coil wound on the porcelain ring, and means for holding the latter in position in a lamp.

In testimony whereof I have signed this specification in the presence of two subscribing witnesses.

BERNARD A. STOWE.

Vitnesses:

JOHN J. ANGEL, HENRY J. Voer

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