DE1052562B - Vacuum jacket for metal vapor discharge lamps - Google Patents

Description

Electric metal vapor discharge lamps in which the discharge vessel of the lamp is transparent Vacuum jacket is enclosed so that heat losses from the discharge space are avoided, are well known. Sodium lamps are the main example of such lamps.

The vacuum jacket of such lamps is constructed similarly to the well-known Dewar vessel, its space is evacuated between the concentric walls. Since the outer and inner walls of such a vessel are closed on one side and connected to each other at their open end, the concentrically nested Ends of the walls held solely by the junction, if not, as already it has been proposed to have one or more resilient spacers between the concentric walls are introduced to eliminate mechanical stresses at the connection point. Instead of several To provide spacers between the concentric walls has also been suggested to use a spacer between the dome-like end walls of the vessel at a remote location from the junction Place to be attached. In this known arrangement, however, the spacer did not become such designed that at the same time also switched off axial movements of the inner wall relative to the outer wall was.

According to the invention, the inner wall of the vacuum jacket is at its from the junction between the inner and outer wall remote end with a cross-section of the inner wall or the Vacuum jacket reducing neck provided around which the inner turn of a support body serving metal frame reaches around, while the outer turn of the metal frame on the rests on the inner circumferential surface of the outer wall, so that the frame even when the two are connected in an airtight manner Walls both radial and axial movements of the walls to each other and intercepts during operation of the lamp enclosed by the jacket, the junction of the two walls of mechanical Stress relieved.

If, in the case of the vacuum jacket according to the invention, that in the space between the walls of the jacket A getter material can be used to improve the vacuum produced after it has been withdrawn from the pump be attached to a wire that forms a conductive loop attached to the frame, so that the getter is vaporized by high frequency currents that can be induced in the wire loop. Since the getter is housed at the end of the jacket vessel, it is attached to the Walls of the vacuum jacket precipitating getter coating, which give rise to a shadow formation

Vacuum jacket
for metal vapor discharge lamps

Applicant:
The British Thomson-Houston Company Limited, London

Representative: Dr.-Ing. W. Reichel, patent attorney,
Frankfurt / M. 1, Parkstrasse 13th

Claimed priority:
Great Britain 7 February 1956

Robert Frederick Weston,
Leicester, Leicestershire (UK),
has been named as the inventor

can, limited to a point where it does not interfere with the light emission of the lamp.

The limitation of precipitation to the end is achieved by heating the remaining sections of the Vacuum vessel walls relieved while the getter is made to evaporate. Should the If the vacuum in the jacket tube is released, the vapor-deposited getter will look up as a result of gas absorption White around and visually indicates the deterioration of the vacuum.

Due to the holder provided for the vacuum jacket according to the invention, the service life of the Vacuum vessel, as has been found, largely enlarged. If necessary, the outer vessel wall be protected by a conical metal cap, which is generally on the outside Surrounds the end of the jacketed vessel when the pump nozzle is pulled off.

In order to explain the invention in more detail, the description of an embodiment follows with reference to the drawings.

Fig. 1 is a longitudinal view of a vacuum vessel for sodium vapor lamps according to the invention;

Fig. 2 is a view of the end showing in plan the shape of the centering, frame-shaped metal bracket shows.

According to the figures, the vacuum jacket consists of concentric inner and outer walls 1 and 2 which are tightly connected to one another at the end where they are attached to a base 3. The base

809 76 & Z242

Claims (2)

generally consists of an insulating material and holds the jacket vessel and the lamp enclosed by the jacket in place. At the end of the vessel remote from the base 3, the concentric walls are centered with respect to one another by a metal bracket 4 which contacts the outer peripheral surface of the neck portion 6 of the inner wall 1 and the inner peripheral surface of the outer wall 2. The bracket 4 can be seen better from FIG. It is made from a single wire which is bent into an inner, approximately C-shaped loop 5 which rests on the neck extension piece 6 of the inner wall 1 and is in engagement therewith. The bracket also has two outer loops 8 which press against the inner peripheral surface of the outer wall 2. The outer loops are an extension of the inner C-shaped loop 5, which are bent back in a concurrent direction. The wire ends are bent upwards at 7. At least one end of the wire holds a frame 9 in which a getter can be accommodated or which itself is partially made from a getter. The frame is a short-circuited conductor that can be heated by induction currents so that the getter attached to it evaporates. If so desired, the end 7 of the metal bracket can be spot welded to the inner loop 5 to reinforce the bracket. In the embodiment shown, however, the wire ends are bent upwards in order to support the frames 9 for the getter, which can be spot welded to the ends 7 of the metal bracket. During production, the bracket 4 is placed on the neck attachment 6 of the concentric, inner vessel wall and then pressed into the outer wall until the bracket reaches the dome-like end section of the outer wall, where its cross-section is already decreasing. The walls are then fused to one another in an airtight manner at their edges, and the base 3 is then cemented to this end of the metal vessel. After the vacuum jacket has been assembled and pumped out through the pump-out nozzle 10, the getter is evaporated and is deposited on the inner surface of the concentric, outer vessel wall, the coating remaining limited to the end section, which is indicated by the hatched part of FIG. If desired, a metal cap 11 can be placed on the end of the vessel to cover the sealed tip of the pump nozzle. Patent claims: 1.Thermally insulating, translucent vacuum jacket for an electric metal vapor discharge lamp, the inner and outer walls of which are closed on one side and are concentric to one another and are connected to one another at their open ends to form the airtight space, in which the inner wall opposite the outer wall by a flexible body located in the space is supported, which is in engagement with the opposite peripheral surfaces of the two walls, characterized in that the inner wall of the vacuum jacket at its end remote from the junction between the inner and outer wall has a neck extension (6 ) , around which the inner turn of a metal frame (4) serving as a support body engages, while the outer turn of the metal frame rests against the inner circumferential surface of the outer wall, so that the frame is also provided with an airtight connection en of the two walls absorbs both radial and axial movements of the walls to one another and relieves the connection point of the two walls from mechanical stresses during operation of the lamp enclosed by the jacket. 2. Vacuum jacket for an electric metal vapor discharge lamp according to claim 1, characterized in that the metal frame consists of a single wire from which an inner, the neck (6) of the inner wall (1) encompassing loop (5) and two outer loops (8 ) are bent, which are in engagement with the inner peripheral surface of the outer wall (2) , and that at least one end of the wire holds a one-piece auxiliary frame (9) which carries a getter or which itself consists partly of a getter and one short-circuited conductor that can be heated by induction currents in order to be able to vaporize the getter. Considered publications:
German patent specifications No. 385 405, 422 664,
630, 879 429; Swiss Patent No. 177 864;
U.S. Patent No. 2,164,307. 1 sheet of drawings © 809 769/242 3.59