US1797031A - Protective device for electrical devices - Google Patents

Description

March 17, 1931. I. H. VAN HORN ET AL 1,797,031

PROTECTIVE DEVICE FOR ELECTRICAL DEVICES Filed March 4, 1924 fNyEN TUE 5: IRYJNE- 'X/ANHURN, WZ'LBUR. A. PIFZTIIZ,

THEIJL'L ATTURZSZE Y.

patented Mar. 17, 1931 V UNITED STATES PATENT OFFICE name a. van norm Ann WILBUB A. PIPKIN, or EAST CLEVELAND, onro, ASSIGNORS To GENERAL ELECTRIC COMPANY, A CORPORATION OF'NEW xonx PROTEUIIV'E DEVICE FOR ELECTRICAL DEVICES Application filed l Iarch 4,

Our invention relates to protective devices for electric incandescent lamps and other electric lamps and devices which comprise an electric energy translating device such as a filament sealed in a glass bulb, and more particularly to such lamps which are provided with an axially depending rod or tube such as the exhaust tube comprised by incandescent lamps made according to the tipless lamp process disclosed in Mitchell and White Patent 1,423,956. According to our invention, the protective device is in the form of a ring or disc having an aperture in the center portion thereof. This allows the protective device to be very conveniently disposed about the end of the exhaust tube .or other glass rodcarried by the lamp or other device. As a specific embodiment of our invention, we disclose herein an improved fuse, but it will be understood that our inventionis of such scope that it relates to other protective devices which are used in connection with incandescent electric lamps and similar devices. n i 25 According to a specific embodiment of our invention we rovide a fuse consisting of a Conducting wlre whose resistance is high compared with that of the rest of the filament circuit connections or portions thereof. This conductor is very small in diameter which lends to the quickness with which the circuit is broken by the abnormal current. The said conductor is surrounded with an insulating material strong enough to resist bursting when the fuse is blown. We prefer to utilize a material which has the requisite strength without being too 'cumbrous. This is especially true when it is desired to in corporate the fuse within the incandescent lamp or other electrical device. One material which we have found to be quite suitable is finely divided zirconium silicate to which is added sodium silicate solution of a specific gravity of about 1.4 to form a paste which can be readily molded. Upon drying this roduces'a-very strong insulating covering or the fuse wire. For the fuse wire we prefer to use comparatively high resistance wire. We have found that the low expansion copper-clad nickel iron wire which is cus- 1924. Serial No. 696,898.-

tomarily used as the sealing in portion of leading-in conductors for electric incandescent lamps is satisfactory for this purpose. This combination of insulating material and fusewire makes a fuse which does not burst when blown. Moreover, the insulating coating adheres very, strongly to the wire and this prevents blowing out at the ends. It is obvious that there are other materials which may be substituted for the zirconium silicate w and sodium silicate to form a suitable insulating coating as the principal requisite is high mechanical strength. Other metals may be substituted for the copper clad nickel iron wire. The principal requisite is that as the wire shall have comparatively high resistance and will blow before the wire in the stem press.

In the accompanying drawing Fig. 1 shows our invention applied to an electric incandescent lamp of the type disclosed in the Langmuir Patent No. 1,180,159; Fig. 2 is a plan view of the protective device and conductors connected thereto; and Fig. 3 is a horizontal 7 section thereof.

' The incandescent lamp shown in Fig. 1 comprises the bulb 10 into which is sealed the hollow glass stem 11 through which extend the leading-in wires 12 13 which comprise portions 14 15 consisting ordinarily of so copper-clad nickel-iron wire having the proper coeflicient of expansion to form a seal with the compressed end .ortion 16 of the stem. The inner portions 1 18 of these leading-in wires are connected to the filament 19 which is suitably supported through the wires 20 whose ends are embeddedin the glass arbor 21 extending from the stem press 16. An exhaust tube 22 is'located within the hollow stem 11 and has its outer sealed end project- ,ing slightly beyond the said stem. Said lamp comprisesthe usual base 23 to the shell of which the conductor 12 is united and to the center Contact 24 of which the other leadingin conductor 13 is united.

According to our invention there is comprised in the electric circuit and connected to the leading-in conductor 13 a fuse 25. As shown in Fig. 3, the said fuse comprises a wire 26 which is preferably of the copper- 100 1 conductors. However, its resistance is highbody, and a stem having a rod extending lon- 'gitudinally within the same and leading-in er which may be accomplished by making it longer or thinner than the portions 14 or 15.

Surrounding the said conductor is an insulating jacket 27. The material used for this jacket is made by mixing finely divided zirconium silicate with a sodium silicate solution of about 1.4 specific gravity to form a paste which may be shaped as is desired.

around the conductor 26.

Upon the breaking of the filament 19 durand mounted within said base and surround ing the end of said exhaust tube.

In witness whereof we have hereunto set our hands this 29th day of February, 1924. IRVING H. VAN HORN. WILBUR A. PIPKI N.

ing the use of the incandescent lamp an are ordinarily springs between the conductors 17 18. This will gradually fuse them down.

,The increase in current consequent. upon the springing of the arc will blow the fuse 25 before the arc has reached the stem press and thus avoid explosion of the lamp which frequently occurs if the arc travels through the stem press.

What we claim as new and desire to secure by Letters Patent of the United States, is:

1.' In an electrical device, the combination of a glass container, a base, a mount comprising an energy translating body, a stem sealed to said container having an exhaust tube extending longitudinally within the same and leading-in wires sealed in said stem, of a ringshaped fuse in series withorle of said leading-in conductors and mounted at the outer end of said stem so as to be enclosed by said container and base and so as to surround said exhaust tube. V

2. In an electrical device, the combinatio of a glass container and a mount comprising a hollow stem sealed to said container, an energy translating device mounted thereon, leading-in conductors sealed in said stem and connected with said energy translating device-and an exhaust tube extending through said stem, a disc-shaped fuse in series with one of said leading-in conductors mounted at the end of said stem and perforated to pass ovler and surround the end of said exhaust tu e.

3. In an electrical device, the combination of a glass container having sealed therein a mount comprising an energy translating wires sealed in said stem, a base and a rin shaped protective device electrically connec ed with said leading-in wires and mounted within said base and surrounding the end of said rod.

4. In an electrical device, the combination of a glass container having sealed therein a mount comprising an energy translating body, and a stem having an exhaust tube extending longitudinally within the same and leading-in wires sealed in said stem, a; base and a rmg-sha edproteotive device electrically connecte wlth said leading-in wires

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