US2495970A - Carbon cooler for arc lamps - Google Patents

Description

,Jan. 31, 1950 H. l. HUFF 2,495,970

CARBON COOLER FOR ARC LAMPS Filed Sept. 6, 1949 Q 20 52 3,1 3??? M 36 f? if 28 131 N I 20 ff 22. I: 4/

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X0 if 40 42 Z? L J? .4 a M 22 3- M Zit j I M 40 20-? 33 3 IIZZINVENTOR, W205? 4 2 HAROLD 1. HUFF j? g BY v 4/ 2/4 j :O. 40 W ATTORNEY I tracted for the removal or Patented Jan. 31, 1950 UNITED STATES PATENT OFFICE CFaREGN COOLER FOR ARC LAMPS Harold I. Huif, Lbs Angeles, Calif. Application September 6, 1949, SerialNo. 114,264

4 Claims.

This invention relates to are lamps for motion picture projectors and the like, of the type in which one or both of the arc carbons are water cooled.

An object of the invention is to provide a highly eificient carbon cooler for an arc lamp.

Another object is to provide a carbon cooler that is readily manipulated to release the carbon, for removal or insertion of the latter.

Another object is to provide a construction for providing exceptionally good heat conductivity between the carbon and the cooling water, of the water jacketed carbon cooler.

Other more specific objects and features of the invention will become apparent from the descrip tion to follow of a particular embodiment thereof.

The present invention constitutes an improvement on the water-cooling attachment of my Patent No. 2,478,533, issued August 9, 1949. In

that patent, the carbon is surrounded by an annular water jacket having a bushing at its front end in intimate contact with the carbon, and having a pair of brushes at its rear end for conduction of electric current to the carbon. In the patented construction, ly relied upon to conduct heat from the carbon to the water jacket proper, where it is transferred to the water. The brushes, being at the rear end of the water jacket, are coo-led on their forward faces by the water jacket, but not on their rear faces. This construction is very satisfactory for small and medium size projectors, but I have found that additional cooling capacity is desirable for large size projectors, and the present invention satisfies this requirement.

Briefly, the present invention comprises a tubular water jacket surrounding the carbon, with a front bushing in intimate contact with the carbon as in the patented design, but with a different brush arrangement, whereby the brushes are surrounded on four sides by, and are in better heat-conducting relation with the water jacket, whereby the brushes can be easil reinsertion of carbons.

In the drawing:

Fig. 1 is a side elevational view with portions broken away of a reflector type projection lamp incorporating a water-cooled carbon support in accordance with the present invention;

Fig. 2 is a side elevational view of the watercooled support;

Fig. 3 is a rear end elevational view of the support;

Fig. 4 is a horizontal section in the plane IV-IV of Fig. 2 showing the brushes pressed against the carbon; and

Fig. 5 is a view generally similar to Fig. 4 but showing the brushes retracted to release the carbon.

Referring first to Fig. 1, there is shown a conthe front bushing is largeventional lamp housin I!) positioned back of a projector H. Near the rear (left) end of the housing I0, is a concave mirror [2 which is axially aligned with the optical system of the projector H. Positioned in the optical axis are the negative carbon #3, and the positive carbon l4 between which the arc is formed. The carbons are longitudinally supported and fed by the conventional carriages, only the carriage it for the positive carbon M appearing in Fig. 1. As these projectors are ordinarily used, carriage [6 not only physically supports the carbon H, but also supplies the current thereto.

. In accordance with my prior patent, and the present invention, a carbon cooler I8 is provided which engages the positive carbon M adjacent its tip, cools the carbon, and constitutes the current connection thereto.

The carriage i6, and a corresponding carriage for the negative carbon it, are usually motor drivento automatically feed the carbons as they burn away, and they still perform this function when my carbon cooler 18 is employed. However, since automatic feeding mechanisms are well known in the art and do not constitute a part of the present invention, no feeding mechanism is described herein. I

The carbon cooler of the presentinvention comprises an annularwater jacket to having an inner wall 200 defining a central passage 2| of slightly larger diameter than the positive carbon i l, and an outer wall 2M, which together with end walls 256 and 2c) define a water chamber 22 through which water is circulated. by way of a pair of conduits 23 and 24, which are shown connected to a header block 25, the latter being connected to supply and waste lines not shown. The water jacket 2!! has at its rear end, a downwardly depending flange Zea to which a forwardly extending stub shaft 2% is anchored. This stub shaft 201; is locked in a socket 27, by a set screw 21b. The socketiil has a downwardly depending shaft Zia formed integrally therewith, which is received in a transverse aperture in a hub 28 and locked in a desired position of adjustment therein by a set screw 2&1). The hub is adjustably supported on the upper end of a standard 29 by a screw 260 which passes through an aperture provided therefor in th standard 29 into a threaded, axial hole in a hub 28. The standard 29 is anchored at its lower end, as by a screw 29a to the lamp frame 3!. The supporting structure described permits adjustment of the water jacket into accurate alignment with the desired axis of the carbon M, so that the latter is supported in the desired position.

.As best shown in Fig. 4, the central passage 2| of the water jacket is threaded at its forward end as indicated at Zia to receive the threaded shank 32a of a bushing 32, the latter having a central apertur dimensioned to snugly engage the carbon l4, and having an enlarged head projecting from the water jacket to provide good heat conduction between the carbon and the water jacket.

To conduct the arc current to the carbon M, the carbon cooler is provided with a pair of brushes 33, the latter being slidable radially in brush passages 33b in the water jacket. The brush passages are defined by walls 20g extending between the inner and outer annular walls 200 and 20d of the water jacket, and sealing therewith. Since the brush passage walls 20g are directly cooled by the water in the jacket, and slidably engage the brushes, they conduct heat away from the brushes rapidly. This not only maintains the brushes relatively cool, but assists materially in cooling the carbon against which the brushes are spring-pressed. Each brush 33 is electrically connected directl to the block 25 by a pig-tail 35 so that the arc current does not have to fiow through the water jacket. The block 25 is electrically connected to the frame 3|, through which the electrical circuit is completed.

To press the brushes against the carbon, the rear end of each brush is engaged by an arm 36 on the end of a shaft 31 that is journalled in a sleeve 38 extending forwardly from the flange 20a at the rear end of the water jacket. The sleeves 38 extend through the water jacket flange Ma, and the shafts 31 extend through the sleeves and have downwardly and rearwardly extending handles 40 on their rear ends. The handles terminate in finger pieces 4!, between which a helical spring 42 is compressed, the ends of the spring being engaged by pins Ala extending inwardly from the finger pieces.

The spring 42 normally maintains the brushes in contact with the carbon with sufiicient force to provide good electrical and thermal conduction, but permit the carbon to be fed therepast as the tip burns away. However, when the carbon is being inserted or removed, such operation is facilitated by retracting the brushes out of engagement with the carbon. This retraction is effected by squeezing the finger pieces 4| together between the thumb and forefinger. In order that the brushes shall be positivel retracted, they are provided with clips 33a on their rear ends that overlie the arms 36 and are engaged thereby when the arms are retracted.

As in my prior patent, a substantial amount of heat is transferred from the carbon to the water jacket through the front bushing 32, this transfer being effected in part by conduction and in part by radiation, and there is some transfer by direct radiation from the carbon to the water jacket within the body of the latter. However, the total heat transfer is very materially augmented in the construction of the present invention, by the mounting of the brushes 33 in the water jacket intermediate the ends thereof, instead of at the rear end as in the patent. This augmentation results both because the brushes are in better heat transfer relation to the cooling water and because they contact the carbon nearer the hot tip thereof, where it is at a higher temperature relative to the brushes. A further advantage of locating the brushes within the water jacket instead of at the rear end thereof, is that it reduces the length of the current path through the carbon. This reduces the voltage drop in the carbon, which increases the electrical efficiency and reduces the total heat generated within the carbon by the current flow therethrough.

Although for the purpose of explaining the invention, a particular embodiment thereof has been shown and described, obvious modifications will occur to a person skilled in the art, and I do not desire to be limited to the exact details shown and described.

I claim:

1. A carbon cooler for a projection arc lamp having a carbon, a frame, and means on said frame for feeding said carbons movable longitudinally into arcing relation with another carbon, said cooler comprising: an annular water jacket dimensioned to surround said carbon and having an inner wall adjacent the carbon and an outer wall spaced from the inner wall, said jacket having a plurality of juxtaposed apertures in said inner and outer walls; brush passage walls extending between said inner and outer walls at each pair of juxtaposed apertures and defining brush passages open at their inner and outer ends and sealed from said water passage; a brush in each brush passage; and means urging said brushes inwardly to contact a carbon within the water jacket.

2. A carbon cooler according to claim 1 in which said last mentioned means comprises: a sleeve means for each brush mounted on said water jacket parallel thereto and extending longitudinally rearwardly from said brushes to the rear end of said jacket; a shaft rotatably supported in each sleeve and having an arm on its forward end engaging the associated brush and an actuating arm on its rear end; and spring means connected to each actuating arm and urging it in direction to press the associated brush inwardly through its brush passage.

3. A carbon cooler according to claim 2 in which: there are two diametrically opposed brushes and brush passages, the associated actuating arms are juxtaposed to each other and substantially parallel to each other, and said spring means comprises a helical spring compressed between said actuating arms.

4. A carbon cooler according to claim 3 including means on each brush engaging the associated arm, whereby said brushes are positively retracted outwardly through said brush passages in response to outward movement of said arms.

HAROLD I. HUFF.

No references cited.

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