US2211597A - Electric incandescent lamp - Google Patents

Description

Aug. i3, w46. E. G. DORGELO Er AL,

ELECTRIC INCANDESCENT LAMP Filed June 6, 1938 Patented Aug. 13, 1940 UNITED sTATEs PATENT OFFICE 2,211,597 ELETRIC INCANDESCENT LAMP Application June 6, 1938, Serial No. 212,178 In the Netherlands June 12, 1937 8 Claims.

Our invention relates in general to electric incandescent lamps, and more particularly to such lamps having a filament sealed within a relatively small envelope and which are designed to 5 operate at a pressure "of more than one atmosphere. Still more particularly, our invention relates to lamps of the above type provided with means for controlling the location of the blackenlng of the bulb whereby the operating life of l the lamp is materially increased.

It is a known fact that in an electric incandescent lamp the efficiency, in other words the emitted number of lumens per watt, increases the more the temperature of the filament is raised. However, this automatically causes a more rapid vaporization of the filament. Since in a standard electric incandescent lamp the life of the lamp is determined by the instant at which the filament burns through, it will be evident that 20 it is not possible in practice to improve the elciency of the lamp without reducing the life of the lamp. The life of such a lamp is, therefore, determined by the time which it takes the f'llament to burn through. During the burning of 25 the lamp, Vaporization of the fllament occurs. The vaporized tungsten particles are deposited as a very thin layer on the wall of the bulb body. However, because of the relatively large bulb surface of ordinary lamps, this layer is not detri- I mental to the light emission even toward the end of the life of the lamp.

The conditions are materially different in an electric incandescent lamp with an operating pressure of more than 1 atmosphere. Such lamps 35 are preferably designed with a bulb of which the internal volume is considerably smaller than further use, the filament, generally speaking, will p be still intact, and this is an indication that the 50 filament, during the burning life of the lamp,

could be loaded more highly without harmful results whereby a higher starting economy can be obtained. 55 The electric incandescent lamp according to In this the invention, which has an operating pressure of more than 1 atmosphere, contains an element which acts as a chimney, whereby a circulation of gas is formed when the lamp is in operation. Due to this gas circulation, the vaporized fila- 5 ment particles are carried along by the gas current and are deposited on the bulb body at points at which they are not detrimental with respect to the light emission. The element which acts as the chimney is, according to the invention, preferably combined with means which retard the gas current created in the lamp by the chimney effect. The filament particles carried along in the gas current will thereby be given an even greater opportunity to be liberated from the gas current and to be deposited.

Partly because of this condition, the applicants have found that the lamp according to the invention can be designed with a maximum inter-- nal diameter of less than mm. It will be evident that a bulb of rather large dimensions might become dangerous to the surroundings because of the pressure in the bulb. By designing the lamp in accordance with the invention, with the element acting as a chimney, and preferably in combination with the above-mentioned retarding means, it becomes possible to design the bulb with very small dimensions without. experiencing detrimental blackening results during the life of the lamp. When the operating pressure in the lamp according to the invention is more than 9 atmospheres, the above-mentioned advantages are present to a still greater extent. In this case, the maximum internal diameter of the bulb body can even be selected so as not to exceed 15 mm.

As a result of the favorable action of the chimney and the retarding means which may be used, and also of the high pressure, the load of the filament in the lamp according to the invention can be'selected higher than in the customary lamps. It is recommended to select those values in such a way that the efllciency of a new lamp is more than 12.5 lumens per watt and preferably more than 15 lumens per watt.

The applicants have found that it is particularly advantageous to have the retarding means located between the chimney and the bulb wall. The retarding means may be of widely different types. The walls of the chimney and/or of the bulb may, for instance, be made rough. It is also possible to form the retarding means of one or several constrictions in the bulb body, or to design them as parts protruding from the chimney. Another possibility is to use a quantity of glass wool or quartz wool or a porous mass as the re- 55 tarding means. If desired, the chimney itself may have a rather thick wall which is made porous, and in that manner serves as a retarding means. The chimney may also be made somewhat conical. It is further possible to employ as the retarding means a wire which preferably is coiled once or several times and which is placed around the chimney. It is also possible to let the inside wall of a helically coiled wire, placed against the bulb wall, serve as the chimney, while the turns will function as the retarding means. It is further possible, according to the invention, to form the filament of such a shape that it functions as the chimney itself.

Further objects and advantages of our invention will appear from the following description of species thereof and from the accompanying drawing, in which:

Fig. 1 is a longitudinal sectional view of an electric incandescent lamp comprising our invention, Fig. la being a similar view thereof on an enlarged scale, and Figs. 2, 3, 4 and 5 are similar views of various modifications of our invention.

Referring to Fig. 1, the lamp there shown is to operate at a voltage of 220 volts and consists of a small tubular bulb or envelope I of quartz or hard glass which has a length of 40 mm. and on internal and outside diameter of 6 and 9 mm. respectively. The said envelope I is filled with a suitable gas such as nitrogen, argon or krypton or mixtures thereof, as is well known in the art. The operating pressure in the lamp is preferably 35 atmospheres or thereabouts while the efiiciency is approximately 15 lumens per watt. A small tube 2 of quartz glass is mounted within the envelope I longitudinally of the same and slightly above a filament 3 of tungsten or other suitable material. The said filament is supported within the envelope I by conventional leading-in or current supply wires 3', 3 which are sealed into the end of the quartz envelope. The tube 2 of quartz serves as a chimney, an upward gas flow (as indicated by the arrows in the drawing) being formed in this chimney by the heat developed by the filament 3. This gas flow changes direction when it arrives in the upper part of the lamp, and ows back to the lower part of the lamp through the space 5 between the chimney and the wall of the bulb. The filament material carried along by the gas flow is mainly released from such flow in the space 5 and ls deposited on the envelope I in the zone A where it is not detrimental to the light emissions.

In the modification shown in Fig. 2, the lamp there illustrated is similar to, and has substantially the same dimensions as, the lamp shown in Fig. 1. While the operating pressure again is 35 atmospheres, the efliciencyis somewhat higher. being approximately 20 lumens per watt. A retarding means in the form of a quantity of glass wool I is placed in the lamp in the space 5 between the chimney 2 and the inside wall of the bulb body. This retarding means acts to impede or retard the gas current created in the lamp by the chimney 2. With such a retarding means, the release of the vaporized filament material takes place in a still better manner than with a chirrmey alone, so that there will be less chance of the vaporized filament materials being deposited at points on the bulb body at which it would be determinental to the light emission.

In the physical embodiment of the lamp according to Fig. 3, the retarding medium consists of a wire 8 helically coiled around the chimney 2, the windings of the wire functioning as the retardlng means.

In the modified form of lamp shown in Fig. 4, the chimney is formed by the inside wall of a coil 9 placed against the inside wall of the bulb body I. 'I'he rising gas flow passes upward through the imaginary cylindrical element which is defined by the inside portions of the coil turns. Above the coil 9, the gas ow then reverses its direction and flows back through the turns themselves which consequently act as the retarding means.

In Fig. 5, a physical embodiment of the lamp according to the invention is illustrated in which the filament I0 is designed as a rather heavy coil so that an upward gas flow is formed within this coil. The desired chimney effect is therefore produced by the filament itself.

The various forms of retarding means mentioned above can be mounted Within the lamp envelope in any one of sereval different ways, it being especially convenient to locate such means on the leading-in wires 3', 3' of the lamp. The chimney within the lamp may also be mounted in different ways. For instance, it is possible to suspend it from one or both wires 3', 3' or to fasten itin the bulb body.

In the appended claims. the use of the expression high-pressure incandescent lamp" is to be considered as referring to lamps in which the operating pressure is higher than one atmosphere.

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

1. A high-pressure electric incandescent lamp operating at an efficiency in excess of 121/2 lumens per watt with a long useful life and comprising a cylindrical envelope having a diameter of less than twenty millimeters and containing a gas filling, a filament sealed within said envelope, and chimney m'eans within said envelope extending longitudinally thereof and located above said filament when the lamp is in operation to thereby create a gas circulation within said envelope.

2. An electric incandescent lamp of the highpressure type operating at an efficiency in excess of' 121/2 lumens per watt comprising a cylindrical envelope having a diameter of less than twenty millimeters and containing a gas filling, a filament sealed within said envelope, chimney means within said envelope extending longitudinally thereof and located above said filament when the lamp is in operation to thereby create a gas circulation Within said envelope. and retarding means Within said envelope and disposed above said filament and in the downward path of said gas circulation to thereby impede the same.

3. An electric incandescent lamp of the highpressure type operating at an eiliciency in excess of 121/2 lumens per watt comprising a cylindrical envelope having a diameter of less than twenty millimeters and containing a gas filling, a fllament sealed within said envelope, chimney means within said envelope extending longitudinally thereof and spaced from the walls thereof, said chimney means being located above said filament when the lamp is in operation to thereby create a gas circulation within said envelope. and retarding means arranged in the space between said chimney means and the Wall of said envelope to thereby impede the downward iiow of the gas circulation created by said chimney means.

4. An electric incandescent lamp comprising an envelope containing a. gas filling, a. filament sealed within said envelope, chimney means within said envelope and spacedi'rom the walls thereof, said chimney means being located above said filament when the lamp is in operation to thereby create a gas circulation within said envelope, and retarding means arranged in the space between said chimney means and the wall of said envelope to thereby impede the downward flow of the gas circulation created by said chimney means, said retarding means comprising a quantity of loosely arranged illamentary vitreous material.

5. An electric incandescent lamp comprising an envelope containing a gas lling, a lament sealed within said envelope, chimney means within said envelope and spaced from the walls thereof, said chimney means being located above said lament when the lamp is in operation to thereby create a gas circulation within said envelope, and retarding means arranged in the space between said chimney means and the wall of said envelope to thereby impede the downward ow of the gas circulation created by said chimney means, said retarding means comprising a porous mass.

6. An electric incandescent lamp of the highpressure type operating at an efficiency in excess of 121/2 lumens per watt comprising a cylindrical envelope having a diameter of less than twenty millimeters and containing a gas filling, a lament sealed within said envelope, chimney means within said envelope extending longitudinally thereof and spaced from the walls thereof, said ,chimney means being located above said lament when the lamp is in operation to thereby create a gas circulation within said envelope, and retarding means arranged in the space between said chimney means and the wall of said envelope to thereby impede the downward ow of the gas circulation created by said chimney means, said retarding means comprising a coil of wire surrounding said chimney means.

7. An electric incandescent lamp of the highpressure'type operating at an eciency in excess of 121/2 lumens per Watt comprising a cylindrical envelope having a diameter of less than twenty millimeters and containing a gas lling, a lament sealed within said envelope,v 'chimney means within said envelope extending longitudinally thereof and spaced from the walls thereof, said chimney means being located above said lament when the lamp is in operation to thereby create a gas circulation within said envelope, and retarding means within said envelope to impede the downward ilow of the gas circulation created by said chimney means, said retarding means comprising one or more obstructions located" ney means, said retarding means comprising a quantity of loosely arranged lamentary ma terial.

EDUARD G. DORGELO. WILLEM ELENBAAS. HENDRICUS J LEMJMENS. MARINUS J. JANSEN.

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