US2540256A - Ventilated arc - Google Patents

Description

awe/Wm 39665 @Wf TEA/5E E. GRETENER VENTILATED ARC Filed April 6, 1949 Feb. 6, 1951 Patented Feb. 6, 1951 VENTILATED ARC Edgar Gretener, Zurich, Switzerland Application April 6, 1949, Serial No. 85,896 In Switzerland April 9, 1948 6 Claims.

The present invention concerns blown carbon arcs of short length and great brilliance.

It is an object of the invention to provide a short are of great brilliance and uniformity of light level.

It is an object of the invention to construct a short carbon are which minimizes stalagmite deposits of sublimed material.

It is an object of the invention to provide a short blown carbon arc with vent means to remove the exhaust gases in which both the vent means and the negative electrode are inclined to the axis of the positive carbon and the arc.

Other objects of the invention will appear as the specification proceeds.

In the drawings, like numerals refer to like parts throughout.

Fig. 1 is an elevation in section of arc form of arc arrangement.

Fig. 2 is an elevation in section of an improved arrangement of an arc arrangement.

Fig. 3 is an elevation of the form shown in Fig. 2 with added are afiecting means.

Referring to Fig. l, a positive carbon 9 is axially aligned with a negative carbon 2 spaced therefrom for the formation of an are -9 therebetween. Positive carbon 9 is mounted in a tubular support of suitable refractor or heat resistant material having a fiat front face 3! with a central channel 32 which extends entirely through support 39. Positive carbon 9 is advanced through channel 32. Around channel 32 in face 3| is a series of orifices I l communicating with an annular reservoir ll within housing 33 which mounts tubular carbonsupport 39. pipe or other supply line 34 is connected to housing 33 for providing air under pressure.

Negative carbon 2 is mounted centrally of exhaust pipe 4 by means of reentrant tube 35 and mounting head 8 from which negative carbon 2 projects. Tube 35 and head 3 form a channel to receive carbon 2 and hold it in axial alignment with carbon 9. Carbon 2 projects from the open end of exhaust pipe 4 which form an annular channel therearound. Pipe i curves away from the carbon axis as shown in the d awing and leads to an exhaust fan or the like.

The above construction subjects the mounting means 8 to the action of the hot exhaust gases I3 and also makes cleaning and adjustment difficult.

Fig. 2 shows an improved form which avoids the above disadvantages. The holes M in face 31 may be orifice shape and direct a substantially annular air stream l2 in conical form upon the arc 0-43. The holes l4 may be merged to provide an annular orifice if desired. Negative carbon 2 is inclined to the axis iii-I0 of positive carbon 9 and an exhaust pipe 33 is likewise inclined to the axis I(3|0 from the upper side. It is preferred to have the plane of the end 5 of exhaust pipe 35 normal to the axis |0I0 of positive carbon 9 which coincides with the axis of arc l-!!. Exhaust pipe 36 is provided with a hole 6 on its under side through which negative carbon 2 extends, but with mounting head 8 outside of thepipe 36. The lower inner surface of pipe 36 between hole 8 and end 5 is formed as a guide support I for carbon 9. As shown in Fig. 2 hole 6 is larger than carbon 9 and allows ample room at 2| for air flow around carbon 9 into exhaust pipe 36 as at 22. The interception and angular relation of the axes as shown in Fig. 2 Where l0-Ii represents the axis of the positive carbon 9 and are 00, l--! represents the axis of negative carbon 2 and 33 represents the axi of exhaust pipe 36.

The secondary air entering hole 8 at gap 2| as shown by the arrow 28 in Fig. 2 combines with the exhaust gases indicated by the other arrows and. prevents the deposit of sublimed or evaporated carbon or similar matter which had been removed from positive carbon electrode 9 and ionized to form are 0- 0. Without the admission of secondar air 29 this material deposits in area 22 and builds up as a solid lump which interferes with the flow of exhaust l3 and requires the frequent removal of the pipe 36 for cleaning. This arrangement b which secondary air 28 is admitted at 2! provides self cleaning action.

As negative carbon 2 i in an oxidizing atmosphere because of air stream 20 it is desirable to surround carbon 2 with a protective coating such as .a very thin layer of electrolytic copper or the like as indicated at 3'1.

In Fig. 3 a magnetic field producing coil !6 is mounted on housing 33. The plane of coil [6 is normal to axis H!lll and it is so spaced along said axis iii-iii from the arc i)i) that the components of the field produced by coil l6 rapidly rotate and focus the arc .li9. This spacing of the coil I6 from center 18 of an are 11-45 is such that the magnetic field components attain an optimum value in planes normal to the axis i i-53 which is also the axis of arc fl0. This arrangement will overcome any tendency to instability of distribution of brilliancy of are caused in some installations by the angularity of axes, l! and Iii-It; of Fig. 2. The field of coil I6 is coaxial with axis 18-40 but diverges as it approaches the arc 9-4 The efiective field strength at point 18 is of course a function of the exciting current as well as the spacing of coil 16. However heating of the coil both by its own current and the are 9-4 is a limiting factor.

Th operation of the device is as follows:

Arc Eil is established by contact of carbon electrodes 9 and 2 which are then drawn apart a short distance such as for example one centimeter. Air is then blown into pipe 3%, reservoir H and orifices H3 in an annular ring around the short are 9-0. This ring of air though initially conical becomes substantially cylindrical in form, smooths the are 0-4! and maintains it in a straight short path with little variation in length. Exhaust pipe 36 is connected to an exhaust fan and suck up the air stream and are fumes. This action assures a smooth air flow without turbulence in the region of arc 0IJ.

Exhaust pipe 36 is connected to a region of slightly reduced pressure, enough to prevent the build up of any back pressure at the entrance 5 of pipe 36. For many installations a strong exhaust draft is not desirable at it tends to disturb the smoothness of are 9-6. pressure within pipe 36 not only induces the air flow 28 but prevents the leakage of exhaust gases 43 at hole 6.

The operation of a blown carbon arc of short length which aiiords little time for oxidation of the positive core material such as cerium causes a stalagmite growth of a carbide pearl or mushroom including the core material at it on negative carbon 2. This growth can be greatly reduced by arranging the axis ill-i0 and the axis i| at an angle and intersecting. The tip 19 of negative carbon 2 is located outside of axis lfil0 and below it in a region of increased oxidizing atmosphere, Also the density of sublimed material is less. The electrodes are preferably coplanar, whereby the arrangement with inclined axes i-l and Iii-49 has been found superior for most applications to that in which the axes are parallel. Best operation is believed to occur when the angles of inclination of axes !i and 33 to axis [8-40 are about equal. Where the assembly is combined with a reflector which is coaxial with are i'!0 pipe 13 is led through the center of such reflector. This arrangement minimizes shadow effects.

While there have been described what are at present considered to be the preferred embodiments of this invention, it will be obvious to those skilled in the art after seeing the present disclosure that various changes and modifications may be made therein without departing from the The reduced invention, and it is, therefore, the purpose of the appended claims to cover by generic terms such changes and modifications as fall within the true spirit and scope of the invention.

I claim:

1. In combination, a positive carbon electrode, means surrounding said electrode and arranged to direct a hollow column of air coaxial with and away from the arc end of said electrode, a negative electrode having an axis disposed at an angle to the axis of said positive electrode, and exhaust means adjacent the arc end of said negative electrode whereby the arc gases and the air column are removed from the are between said electrodes.

2. An arc lamp, having a positive carbon electrode, a negative electrode, means concentric with said positive electrode to blow a hollow cylindrical column of air toward said negative electrode, exhaust means to withdraw the arc gases and the blown air from the are between said electrodes, said negative electrode and said exhaust means being disposed at an angle to the axis of said positive electrode and on opposite sides thereof.

3. The combination set forth in claim 2, said exhaust means having means to admit secondary air adjacent said negative carbon.

4. The combination set forth in claim 3, a holder for said negative electrode, said holder being positioned outside of said exhaust means.

5. The combination set forth in claim 4, the major portion of the arc end of said negative electrode being positioned below the axis of said positive electrode and in an area of oxidizing atmosphere.

6. In a blown arc, exhaust means, negative electrode mounting means, said exhaust means being adjacent the negative electrode and said mounting means, both said means being noncoaxial with the arc axis whereby shading of the effective light beam is minimized, the life of each said means is maximized, and the smoothness of the arc cylinder is maintained.

EDGAR GRETENER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,029,787 Beck June 18, 1912 1,995,144 Crocker Mar. 19, 1935 2,305,757 Beck Dec. 22, 1942

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