US3441770A

US3441770A - Electric incandescent lamp with shock and vibration resistant filament support structure

Info

Publication number: US3441770A
Application number: US629461A
Authority: US
Inventors: Wilfred H Hough
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1967-04-10
Filing date: 1967-04-10
Publication date: 1969-04-29
Anticipated expiration: 1986-04-29

Description

April 29, 1969 w. H. HOUG'H 3,441,770

, ELECTRIC INCANDESCENT LAMP WITH SHOCK AND VIBRATION.

masxsmm FILAMENT SUPPORT STRUCTURE Filed April 10. 1967 lnventoT-i WiLF'T'fiBd I-I. Hough by 62%- f His Arm-Q hey United States Patent 3,441,770 ELECTRIC INCANDESCENT LAMP WITH SHOCK AND VIBRATION RESISTANT FILAMENT SUP- PORT STRUCTURE Wilfred H. Hough, Cleveland Heights, Ohio, assignor to General Electric Company, a corporation of New York Filed Apr. 10, 1967, Ser. No. 629,461 Int. Cl. H01k 1/30 US. Cl. 313-113 8 Claims ABSTRACT OF THE DISCLOSURE In an incandescent lamp, especially of the sealed-beam type, having a filament supported on lead-in wires which are tied together by a bridge and are formed below the bridge into spring portions which permit the filament, lead wires and bridge to flex as a unit in all directions, there is provided a resilient damper wire which extends transversely of the bridge with its ends engaging the bulb wall at opposite sides thereof and which has its mid-portion frictionally engaged by the bridge and held thereby in a depressed or bowed position.

BACKGROUND OF THE INVENTION Field of the invention This invention relates to electric incandescent lamps comprising a sealed envelope containing an incandescible filament, and is particularly concerned with lamps which are adapted for use in service conditions where they are subjected to shock and vibration.

Description of the prior art Although the invention is not limited thereto, it will be described herein with particular reference to lamps of the so-called sealed-beam type and which are used in railway service, particularly train warning lamps which are used on railway switch locomotives in a fixture which rotates two or three lamps to produce a warning flashing signal. To handle roadbed and engine vibration along with shock occasioned by coupling of the engine with other equipment, the lamp must be able to withstand vibration and shock in all directions without distortion and premature destruction of the filament.

Some success has been achieved heretofore by forming each of the lead-in conductors in separate sections spaced apart longitudinally and electrically and mechanically interconnected by a coiled spring elastically fitted over and bridging the gap between the sections, as in Patent 2,497,567 to J. E. Stone, or by forming intermediate portions of the lead-in wires with laterally extending and opposed arcuate sections of semicircular shape which serve as a cushion or spring, as in Patent 2,497,566 to J. E. Stone et al. In a further attempt to avoid the adverse effects of extreme shock conditions, lamps of the first-mentioned type were provided with bumper or stop members in the form of rigid wires fixed at their center to respective lead wires, extending laterally of the plane including the filament and lead-in wires, and terminating at each end a short distance from the curved reflector surface of the lamp whereby to limit the deflection of the filament mount structure to a degree less than that which would cause it to take a permanent set.

SUMMARY OF THE INVENTION It is an object of the invention to provide an improved construction which will materially improve the service life of lamps which are subjected to severe shocks and vibration.

Accordingly, in accordance with the invention, there is provided a construction in which the filament and its adjacent supporting structure is supported by spring means which leaves it free to vibrate in all directions and additionally, there is provided a damper means which functions as a true mechanical damper by imparting friction to the vibrating filament supporting structure whereby it settles back almost immediately when displaced in any direction.

In accordance with a preferred aspect of the invention, the damper is in the form of a length of resilient or springy wire which extends transversely of the filament supporting structure with its opposite ends engaging the wall of the lamp envelope and which is frictionally engaged at its mid-section by the filament supporting structure and held thereby in a depressed or bowed position against the action of the more powerful filament supporting spring means so that it is always ready to perform its damping action irrespective of the direction of displacement or flexure of the filament supporting structure.

BRIEF DESCRIPTION OF THE DRAWING Further features and advantages of the invention will appear from the following detailed description of a species thereof and from the drawing wherein:

FIG. 1 is a tilted view of a lamp having a resilient filament supporting and damping construction in accordance with the invention; and

FIG. 2 is a section through the lamp in a plane which includes one of the 1ead-in wires and is normal to the plane which includes the filament and both of its supporting lead-in wires.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the drawing, the lamp illustrated therein is of the sealed-beam type comprising an envelope consisting of a pressed glass concave reflector section 1 and a pressed glass cover or lens section 2 which are hermetically sealed together at their peripheries. The interior surface of the reflector section 1, which may be of paraboloidal or any other desired optical shape, has thereon a reflecting coating 3 which may be of a metal such as vapor-deposited aluminum or silver.

The reflector section 1 carries a terminal structure which comprises a pair of metal ferrules or thimbles 4 having feathered edges which are hermetically sealed and embedded in the thickness of the glass section 1 around the margins of openings -5 therein, so that said ferrules constitute part of the envelope wall. The envelope 1, 2, is exhausted and preferably gas-filled, through an aperture 6 (FIG. 1) at the apex of the reflector section 1, by way of an exhaust tube (not shown) which is sealed to the exterior of said reflector section in communication with the aperture 6 and is ultimately sealed or tipped off close to the envelope wall.

The envelope contains a filament 7 which is here illustrated as a helical coil of tungsten wire which extends transversely across the optical axis of the reflecting surface 3. The filament 7 is connected at its ends to the inner end portions 8 of a pair of lead-in conductors 9 which extend into the envelope in parallel spaced relationship from respective ferrules 4 in which the outer end portions 10 of the leads 9 are secured, for example by a quantity 11 of solder or brazing material. The inner portions 8 of the lead-in conductors are insulatively and rigidly tied together by a suitable bridge means, here illustrated as comprising a glass rod 12 which carries at each end a pair of spaced support Wires 13 having one end embedded in the rod 12 and the other end secured, as by welding, to the adjacent inner lead wire portion 8. Supplemental filament support wires 14 each has one end embedded in the rod 12 and the other end looped about an intermediate portion of the filament 7.

The filament 7, upper lead wire portions 8 and bridge 12 are resiliently supported for flexure in any direction by the provision of suitable spring means. As herein illustrated by way of example, the lead-in conductors 9 are made of a suitable springy material and are formed with integral intermediate helically coiled portions 15. For that purpose, the lead wires 9 may be made of a material such as stainless steel, molybdenum, tungsten or, preferably a copper base alloy containing zirconium and sold under the trademark Amzirc by Climax Molybdenum Company.

Although the resilient supporting structure thus far described is quite effective in minimizing damage to the filament 7 when the lamp is subjected to shock and vibration, still further improvement is obtained in accordance with the invention by the provision of a damper means. The damper member is in the form of a normally straight length of resilient wire 16 which extends transversely of the bridge member 12 with its ends engaging the wall of the reflector section 1 of the envelope at opposite sides thereof and adjacent its periphery, and with its midportion engaged by the composite bridge means 12, 13 and held thereby in a depressed position so that the wire is bowed downwardly toward the apex of said reflector section 1 and the anchored ends of the lead-in conductors 9.

The damper wire may be located as shown by the broken lines 16a in FIG. 1 where it is engaged by the glass bridge rod 12 substantially at the center thereof and its ends are held down against the edges of an annular shoulder 17 at the periphery of the envelope reflector section 1. Although good results may be obtained with the damper wire 16a so located, it is possible that under conditions of severe shock and vibration, the wire 16a may shift its position away from the normal to the bridge member 12, even to such a degree that it assumes a position virtually parallel to the bridge member 12 where it comes into short circuiting engagement with the lead-in conductors 9. Such an extreme degree of shifting of the damper wire 16a may be prevented by fixedly tacking or sealing one end thereof to the wall of the envelope section 1, or even securely sealing one end in the rim of the envelope between the peripheral sealing surfaces of the envelope sections 1 and 2. The other end of the damper wire 16a must, in that event, remain free to rub against the surface of the envelope wall so that the wire is free to flex upon movement of the assembly of bridge 12, filament 7 and inner lead wire portions 8.

However, in a presently preferred arrangement, the damper wire 16 is located to extend between the spaced pair of support wires 13 at one end of the bridge where it is frictionally engaged at its mid-point by one of those wires. Such an arrangement avoids the shifting of the wire 16 to the degree referred to above in connection with a wire located at 16a. It is preferred that both ends of the wire 16 be in free frictional engagement with the envelope wall. However, if desired, one end of wire 16 may be tacked or sealed to the envelope wall. The wire 16 may be made of a material of such size and composition that it is sufficiently resilient or springy to perform its damping function. To that end, the wire 16 is preferably made of molybdenum, although tungsten is also quite suitable.

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

1. An electric incandescent lamp comprising a sealed envelope, a. filament in said envelope, lead-in conductors anchored to and supported from the wall of said envelope and extending into the envelope in the same general direction and connected at their inner ends to said filament, bridge means extending between and insulatively and rigidly tying together the inner end portions of said lead-in conductors, said lead-in conductors being provided intermediate their anchored ends and said bridge means with resilient spring means permitting flexure of the filament and inner ends of the lead-in conductors as a unit in all directions, and damper means comprising a resilient wire member which extends transversely of said bridge means with its ends engaging the bulb wall at opposite sides thereof and with its mid-portion frictionally engaged by said bridge means and held thereby in a depressed position so that said wire is bowed downwardly toward the anchored ends of the lead-in conductors, at least one of the ends of said wire member being free to rub against the envelope wall upon flexure of said wire member.

2. A lamp as set forth in claim 1 wherein said bridge means comprises a glass rod having a pair of spaced support wires secured to each end thereof and projecting therefrom toward and secured to an adjacent one of said lead-in conductors, and said resilient damper wire has its said mid-portion located between one of said pair of spaced support wires.

3. A lamp as set forth in claim 2 wherein said resilient spring means is a helically coiled spring portion of each of the lead-in conductors.

4. A lamp as set forth in claim 1 wherein said resilient spring means is a helically coiled spring portion of each of the lead-in conductors.

5. An electric incandescent lamp of sealed beam type comprising a sealed envelope including a concave reflector section and a cover glass section sealed at their peripheries, a filament in said envelope, lead-in conductors anchored to and supported from the wall of said reflector section adjacent its apex and extending into the envelope in the same general direction and connected at their inner ends to said filament, bridge means extending between and insulatively and rigidly tying together the inner end portions of said lead-in conductors, said lead-in conductors being provided intermediate their anchored ends and said bridge means with resilient spring means permitting flexure of the filament and inner ends of the lead-in conductors as a unit in all directions, and damper means comprising a resilient wire member which extends transversely of said bridge means with its ends engaging the wall of said concave reflector section of the envelope at opposite sides thereof and adjacent its periphery and with its mid-portion frictionally engaged by said bridge means and held thereby in a depressed position so that said wire is bowed downwardly toward the apex of said reflector section, at least one of the ends of said wire member being free to rub against the envelope wall upon flexure of said wire member.

6. A lamp as set forth in claim 5 wherein said bridge means comprises a glass rod having a pair of spaced support wires secured to each end thereof and projecting therefrom toward and secured to an adjacent one of said lead-in conductors, and said resilient damper wire has its said mid-portion located between one of said pair of spaced support wires.

7. A lamp as set forth in claim 6 wherein said resilient spring means is a helically coiled spring portion of each of the lead-in conductors.

8. A lamp as set forth in claim 5 wherein said resilient spring means is a helically coiled spring portion of each of the lead-in conductors.

References Cited UNITED STATES PATENTS 2,497,567 2/1950 Stone 3l327l 2,633,548 3/1953 Kramel 313113 2,824,995 2/1958 Kirk 313271 3,114,069 12/1963 Peek et a1 3l3269 3,270,238 8/1966 Mosby 313279 3,375,393 3/1968 Morgan 313-278 X JAMES W. LAWRENCE, Primary Examiner.

E. R. LA ROCHE, Assistant Examiner.

US. Cl. X.R. 313-269, 271, 278