US3045642A

US3045642A - Vacuum pumps of the getter type

Info

Publication number: US3045642A
Application number: US747475A
Authority: US
Inventors: Auzolle Robert; Chaumette Paul; Garin Paul; Prugne Pierre
Original assignee: Commissariat a lEnergie Atomique CEA
Current assignee: Commissariat a lEnergie Atomique et aux Energies Alternatives CEA
Priority date: 1957-07-12
Filing date: 1958-07-09
Publication date: 1962-07-24
Anticipated expiration: 1979-07-24
Also published as: GB859515A; DE1099689B; BE568835A; FR1178844A; NL268802A; CH346618A; LU36203A1

Description

July 24, 1962 Filed July 9, 1958 R. AUZOLLE ETAL 3,045,642

VACUUM PUMPS OF THE GETTER TYPE 3 Sheets-Sheet 1 July 24, 1962 Filed July 9, 1958 gm N R. AUZOLLE ETAL 3,045,642

VACUUM PUMPS OF THE GETTER TYPE 3 Sheets-Sheet 3 crgie Atomique, Paris (Seine), France, a State administration Filed July 9, 1958, Ser. No. 747,475 Claims priority, application France July 12, 1957 9 Claims. Cl. 118-49) The present invention relates to apparatus in which successive portions of a wire (this term being taken in its broadest meaning and including all elongated elements, either in the form of wires of rounded section or in the form of fiat bands or strips) are vaporized in a vacuum chamber by heating means located in such a chamber, so as to obtain, by condensation of the metal vapor on the wall of the chamber, what is known as a getter effect, said successive wire portions being supplied in said chamber by a feed mechanism generally constituted by a spool from which said wire is unwound by suitable driving means. i

The object of the present invention is to provide an apparatus of this kind which is better adapted to meet the requirements of practice than those known at the present time.

In such known apparatus of this kind, the feed mechanism, in particular the spool from which the getter metal wire is unwound, is located inside the vacuum chamber. Such apparatus have some drawbacks. In particular, as the wire, to be vaporized, must be heated to high temperatures, for instance averaging 2000 C., the feed mechanism, which is located close to the heating means (since both are located in the vacuum chamber) is brought to relatively high temperature (several hundreds of degree C.) which, in addition to the difliculty of achieving a good lubrication in a vacuum, tends to produce jamming of the getter metal wire in its guiding means.

To obviate such drawbacks, according to the present invention, the feed mechanism is placed in a gastight casing located on the outside of the vacuum chamber but in communication therewith, the getter metal wire being guided by suitable means from said mechanism to the inside of the vacuum chamber, where it is vaporized by the heating means.

Thus, the feed mechanism is no longer subjected to the heat of the heating means and the above mentioned drawback is avoided.

A preferred embodiment of the present invention will be hereinafter described with reference to the accompanying drawing, given merely by way of example and in which:

FIG. 1 is a partly diagrammatic vertical section of a vacuum pump made according to the invention.

FIG. la is a sectional view on line I-I of FIG. 1.

FIG. 2 is another vertical sectional view of the lower portion of the apparatus taken in a plane at right angles to the section plane of FIG. 1.

FIG. 3 is a plan view of said apparatus.

FIG. 4 is a sectional view on the line IV-IV of FIG. 2, this sectional view being made on an enlarged scale.

The apparatus shown by the drawing, which is a vacuum pump, includes a gastight vacuum chamber the bottom plate of which, for instance made of steel, is shown at 1. An auxiliary gastight casing 2 is fixed by any suitable means under said plate 1, the upper wall of said casing 2 being in gastight contact with the under surface of plate 1, with the interposition of sealing means such as 3.

This casing 2 communicates with the inside of the vacuum chamber located above plate 1 through a passage 4 3,045,642 Patented July 24, 1962 located in the upper Wall of casing 2 and a passage 5 located in plate 1. The lower end of casing 2 is closed by a plate such as 6 fixed at 7 with the interposition of sealing means 8.

The feed mechanism mounted in said casing 2, and for instance supported by a plate 6, includes the following elements:

A spool 9 from which the getter metal wire 10 is to be unwound,

And means for propelling wire 14), for instance step by step, said means including two rollers 11 and 12 (the respective cooperating surfaces of which are serrated), at least one of said rollers being driven step by step through means which will be hereinafter described, a spring device 13 being arranged to apply said rollers against each other.

The Whole is carried by a frame 14 fixed by supports 15 on plate 6.

When leaving

rollers

11 and 12, Wire 10 is engaged in guiding means which extend through

passages

4 and 5 and which convey the end of the wire into contact with a crucible 6t) heated in any suitable manner, for instance by electron bombardment, as diagrammatically shown on FIG. 1. For this put-pose, crucible 60 is carried by a high voltage electrode 61 and it is surrounded by an electron emitting filament 63 supported by two

low voltage electrodes

64 and 65 by means of which it is heated by Joule effect. The above mentioned electrodes pass through plate 1 with the interposition of

insulating elements

62, 66 and 67. i

The above mentioned guiding means include a rectilinear portion including several tubes such as 16, 17, 18, 19, adapted to be easily assembled together, said tubes being for instance made of steel. One of these tubes 18 is provided with external screw-threads and carries two

nuts

20 and 21 by means of which it is possible to adjust, both in height and in direction, the wire guiding means with respect to the support of the pump.

The curvilinear portion of the guiding means which follows tube 19 is constituted by two

shell sections

22, 23 at least one of which is made of graphite or any other self-lubricating material, these two

sections

22 and 23 being connected together by springs such as 24.

Another graphite tube 25 is fixed to the end of this

curved portion

22, 23.

Such an arrangement occupies little space inside the vacuum chamber of the pump and on the other hand the feed mechanism is protected against the heat supplied by the heating means. The feed mechanism is further protected against condensations of metallic vapors owing to the provision of a sheltering baffle 26 located above

passages

4 and 5, this bafile being preferably made of synthetic lava.

The feed mechanism and its casing 14 must be electrically insulated from the metallic portions of the apparatus constituted by the Wall of the vacuum chamber and that of casing 2, this in view of the high electric voltage which generally exists between the end of the wire that is being unwound and the electrode 61 which supports crucible 60.

For this purpose, the supports 15 of frame 14 are made from the outside. I

For this purpose, a rod 27 extends through plate 6 with the interposition of gastight bellows 29.

Rod 27, which is for instance made of tin bronze, is guided with respect to plate 6 by three ball bearings 28 disposed at to one another and having their axes at right angles to that of rod 27. The top portion of rod 27 is mounted inside bellows 29, said bellows being soldered to plate 6 at 30 and to rod 27 at 31.

The lower portion of rod 27 carries two

ball bearings

32, 33 between which is interposed, in a hold 34 provided in rod 27, an eccentric 35 the spindle 36 of which, controlled from the outside at 37, rotates in

bearings

38, 39 mounted in a guiding sleeve 40. Shaft 37, when rotated, therefore produces reciprocating displacements of rod 27.

The upper end of rod 27 carries a piece 41 made of an insulating material and the top end of which is turn carries a piece 42 which acts, through two pawl 43 and 44 acting in opposition, to drive, under the effect of the reciprocating movements of rod 27, a ratchet wheel 45 mounted on the spindle 46 of roller 11.

Rollers

11 and 12 are operatively connected by pinions 47 and 48. The various spindles are mounted on ball bearings 49, 50, 51, 52 (FIG. 3).

In a general manner, while we have in the above description, disclosed what we deem to be a practical and efiicient embodiment of our invention, it should be well understood that we do not wish to be limited thereto as there might be changes made in the arrangement, disposition and form of the parts without departing from the principle of the present invention as comprehended within the scope of the accompanying claims.

What we claim is: I

1. In an apparatus of the type described in which a metal capable of producing a getter effect is vaporized in a vacuum,'the combination of means forming a vacuum chamber, a gastight casing located on the outside of said chamber, said chamber and said casing having adjoining respective walls in gastight contact with each other, said walls being provided with corresponding holes for placing the inside of said chamber in communication with the inside of said casing to extend the vacuum of said chamber into said casing, means extending from the inside of said casing to the inside of said chamber and passing through said holes for guiding a wire of said metal from said easing into said chamber, heating means located inside said chamber for vaporizing said metal wire in said chamber at the outlet of said guiding means, a protecting baffle in said chamber surrounding said guiding means above said connecting holes, said baffle preventing condensation of metallic vapors in said casing, a feed spool mounted in said casing, said wire being wound on said spool, and driving means for unwinding said wire from said spool and propelling it through said guiding means from said easing into said chamber.

2. A combination according to claim 1 in which said casing is located under said chamber.

3. A combination according to claim 1 in which th portion of said guiding means located in said chamber consists of a swan-neck shaped sheath.

4. A combination according to claim 1 in which said guiding means consist of a plurality of sheath elements removably assembled together.

5. A combination according to claim 1 in which at least a portion of said guiding means is made of graphite.

6. A combination according to claim 1 in which said a reciprocating longitudinal movement, and means be- 'tween the first mentioned end of said rod and said spool for rotating said spool step by step in response to said reciprocating movement of said rod end.

8. In an apparatus for the evaporation of metal strips, a vacuum chamber, a second chamber 'adjoining a wall of said vacuum chamber, registering holes in the adjoining walls of said two chambers to establish a communicating vacuum in both chambers on evacuation, heating means in said vacuum chamber to vaporize the metal strip, a supply of said metal strip and strip advancing means in said second chamber, means guiding said strip from said strip advancing means through said registering holes into the vacuum chamber, a protecting bafile in said vacuum chamber surrounding said guiding means above said holes, said baflle preventing condensation of vaporized metal in said second chamber, and means actuating said strip advancing means, said actuating means passing through a seal from said second chamber to the outside.

9. In combination with the vacuum chamber of an apparatus for the vacuum evaporation of a metal strip, a second chamber tightly adjoining said vacuum chamber,

registering holes in the adjoining walls of said two chambers to establish a communicating vacuum therein on evacuation, a supply of metal strip and strip advancing rollers in said second chamber, heating means in the vacuum chamber to vaporize the metal strip, means guiding said strip from said rollers through said registering holes into the vacuum chamber, a protecting baffle in said vacuum chamber surrounding said guiding means above said holes, said baffle preventing condensation of vaporized metal in said second chamber, and reciprocating means stepwise advancing at least one of said rollers, said reciprocating means including a rod operatively connected to one of said rollers and passing through a wall of said second chamber, a gastight bellows secured to said wall and the outer end of said rod and forming a vacuum tight seal, and eccentric driving means imparting reciprocating movements to said rod.

References Cited in the file of this patent UNITED STATES PATENTS 2,402,269 Alexander et al June 18, 1946 2,554,902 Godley May 29, 1951 2,664,853 Schuler Jan. 5, 1954 2,812,270 Alexander Nov. 5, 1957 FOREIGN PATENTS 551,220 Great Britain Feb. 12, 1943 654,228 Great Britain June 13, 1951 1,0=51,M7 France Jan. 14, 1954 878,884 Germany June 8, 1953