US2400916A

US2400916A - Safety lamp

Info

Publication number: US2400916A
Application number: US553517A
Authority: US
Inventors: Joseph D Ceader
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1944-09-11
Filing date: 1944-09-11
Publication date: 1946-05-28
Anticipated expiration: 1963-05-28

Description

May28, 1946. b, C ADE 2,400,916

SAFETY LAMP Filed Sept. 11, 1944 A, I I! Patented May 28, 1946 SAFETY LAMP Joseph D. Ceader, East Cleveland o hio, assignori to General Electric Company, acorporation of New York Application September 11, 1944, Serial No'. 553,517-

1 Claim.

This invention relates to electric safety lamps for the use of miners and others who work where inflammable, explosive, or other thermo-reactive atmospheres or gases may be encountered. The invention aims to provide protection against dangeifrom breakage of a lamp bulb by promptly stopping the flow of current to the lamp. A further aim is to accomplish this in a simple and convenient way, without necessity for heavy or complicated apparatus; on the contrary, the equipment can be made very light and compact, and easy and inexpensive to make and use. The invention is applicable to lamps with plural end contacts on their bases, and to lamps with plural filaments, as well as to the single filament, single contact lamps in connection with which it is here illustrated and particularly explained. Various features and advantages of the invention will appear from the description of species and forms of embodiment, and from the drawing.

In the drawing, Fig. 1 is a side view of a safety lamp equipment conveniently embodying the invention, certain parts being partly broken out and in section; and Fig. 2 is a corresponding end view.

Figs. 3 and 4 are views similar to Figs. 1 and 2 I illustrating a modification.

Fig. 1 shows the invention as embodied in a miners safety lamp equipped with a known type of fastener I for mounting the lamp on a miners cap (not shown), and with a flexible cable 2 for connecting it to a battery (not shown) that may be carried on the miners back, or to any other source of current. These parts I, 2 are shown attached to a holder or socket 3 that includes an external casing or shell 4 provided with an insulative lining 5 and having mounted therein an insulative part 8 that carries screw connectors I, l for lead-wires 8, 8 of the cable 2, as well as contacts 9, I0 for an electric lamp II. The lamp I I may be an incandescent filament lamp, or a discharge lamp of fluorescent or other type, or any other suitable electric lamp. As shown, it comprises a shouldered bulb with a parabolic, spherical, or otherwise rounded rear reflector portion I2 and a spherically rounded radiationtransmitting front portion I3, as well as a neck which provides a mounting orbase portion I4, or is equipped therewith. Associated with this portion I4 of the lamp are contact terminals I5, I6 for coacting with the contact means 9, I 0 already mentioned as associated with the holder 3. The lamp contacts shown are a center contact I5 at the end of an insulative conical projection on the base I4, and an annular contact shoulder I6 surrounding this conical projection. The socket contacts shown are a C-bent and somewhat resilient metal strip 9 fixed on the insulative part 6 and electrically connected to one of the connectors I, and a helical metal wire compression spring Ill accommodated in the shell lining 5 around the contact 9 and electrically connected to the other connnector 1 by a metal strip I7 set into the part 6. This spring I0 bears against the lamp base shoulder I6 and urges the base I4 and its center contact I5 away from the center contact 9 of the socket 3.

For normally holding the lamp II and its base I4 in place in the holder or socket 3, and likewise holding the contacts I5 and 9 together, one or more retainers or hooks I8 associated with the holder 3 are arranged to hook over suitable shoulder(s) on the lamp bulb: viz., in the device here illustrated, over the shouldered front bulb portion I3. As shown in Figs. 1 and 2, three hooks I8 are mounted around the open front end of the holder 3 so that they can swing together on the bulb end I3 after the bulb has been placed in the holder, or vice-versa. For this purpose, the rear ends of the hooks I8 may be pivoted on a ring [9 fitted into an annular-groove in the forward end of the holder shell 4, behind a shoulder formed by a flare 20 at the mouth of this shell.

To hold the hooks I8 together in engagement with the shouldered bulb end I3, a tie in the form of a springy, resilient wire ring 2| is shown embracing the shanks of the hooks (and the corresponding portion of the bulb), behind the greatest spread of the hooks at the largest diameter of the bulb. To supplement friction in holding the tie ring ZI in place, the shanks of the hooks may have serrations or rounded notches 22 for a ring to engage in. The spring of the ring 2|, supplemented by some resilient flexure of the hooks I8, makes it easy to assure a convergent grip of the hooks on the bulb II with considerable resilient pressure.

So long as the bulb II is intact, the hooks I8 hold it in the position shown in the holder, with the spring I6 under elastic compression against the base contact I0, and the center contacts I5, 9 engaged. If and when the bulb II' is broken, its diminished strength assures its being collapsed and shattered by the force of the spring I6 and the convergent resilient pressure of the hooks I8. When this happens, the spring I6 is free to push the base I4 outward in the holder or socket 3, separating the contacts I5, 9, breaking the circuit, and stopping the flow of current. The usual gas filling in the lamp II serves to prevent con- 7 tact or the surrounding atmosphere with the electric translation means (e. g., filament(s) or electrode(s)) in the lamp bulbuntil these parts have cooled to the point where there is no further danger of explosion or the like. I V v The device illustrated in Figs. 3 and 4: differs from that just described in having only a single hook l8, which hooks over the front bulb end 13 and bears thereon symmetrically around the bulb axis, having for this purpose a plurality of radial arms or fingers 23. The rear end of this hook I8 is shown as pivoted at 9 to lugs on a collar 24 clamped around the open end of the holder shell 4 over an annular shoulder 25 embossed in the shell. When the bulb II has been placed in the holder 3 and the hook l8 swung intoposition'as shown, the pressure of the spring I6 and the bulb ll against the hook l8 and its fingers 23 retains the hook against accidental disengagement as l0ng as the bulb remains intact. When the bulb H is broken, the force of the spring l6 collapses and shatters it and also pushes the base l4 away from the contact 9 and breaks the circuit, etc., just as in the device of Figs. 1 and 2.

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

In a lamp holder of the type comprising a socket including a shell adapted to receive the base of an electric lamp and containing contacts engageable with contacts on said lamp base, and spring means urging the lamp outwardly of the socket and out of engagement with at least one of the sockets contacts, means to retain the lamp in said socket comprising a plurality of hookshaped fingers pivotally supported from said shell at their rearward ends to hook over the front end of the bulb of said lamp to retain the lamp in the socket, and resilient ti means embracing the bulb and said fingers to hold said finger in closed position around said bulb.

JOSEPH D. CEADER.