US3197945A

US3197945A - Sorption pump apparatus

Info

Publication number: US3197945A
Application number: US91837A
Authority: US
Inventors: Zaphiropoulos Renn
Original assignee: Varian Associates Inc
Current assignee: Varian Medical Systems Inc
Priority date: 1961-02-27
Filing date: 1961-02-27
Publication date: 1965-08-03
Anticipated expiration: 1982-08-03
Also published as: GB939395A

Description

Aug- 3, 1965 R. zAPHlRoPouLos 3,197,945

SORPTION PUMP APPARATUS Filed Feb. 27. 1961 INVENTOR. RENN ZAPHIROPOULOS w w ATTORNEY United States Patent 4 3,197,945 SGRPTIUN PUMP APPARATUS Renn Zaphiropoulos, lLos Altus, Calif., assignor to Varian Associates, Palio Aito, Calif., a corporation of Caifornia l Filed Feb. 27, 1961, Ser. No. 91,837 2 Claims. (Cl. 55-269) The present invention relates in general to sorption vacuum pumps and more particularly to novel means for cooling the absorbent material in a sorption vacuum pump.

Prior art sorption vacuum pumps 'have proved generally unsatisfactory for some vacuum applications because of one or more of the following reasons: inadequate pumping capacity because of limited quantities of absorption material utilized, inadequate pumping capacity due to inefiicient cooling of absorption material, and pump configurations which are relatively expensive to fabricate and produce.

The present invention provides a unique sorption vacuum pump which manifests none of the above disadvantages.

It is, therefore, the object of the present invention to provide a sorption vacuum pump which is very efi'icient in its operation, has a large pumping capacity, and whose components are relatively inexpensive to tool and fabricate.

One feature of the present invention is a novel sorption vacuum pump interior cooling means which is extremely efiicient and is easily tooled and assembled.

Another feature of the present invention is the use of an exhaust valve which allows a release of the interior pressure of a sorption vacuum pump upon completion of a pumping cycle.

Another feature of the present invention is a unique exterior design which provides a sorption vacuum pump of great mechanical strength and durability.

The above features and advantages of the present invention will become more apparent upon a perusal of the following speeification taken in connection with the accompanying drawings wherein:

PIG. 1 is an exploded perspective view of the sorption pump apparatus of the present invention,

FIG. 2 is an enlarged plan cross sectional plan view taken along the lines 2-2 in the direction of the arrows of the apparatus of FIG. 1, and

FIG. 3 is an enlarged fragmentary Vertical cross sectional view taken along the lines 3-3 in the direction of the arrows of the apparatus of FIG. 2.

Referring now to FIGS. 1 through 3 there is shown a sorption vacuum pump casing having a hollow cylindrical side wall envelope 11 which is sealed by a bottom end wall 12 and a top end wall 13. The

end walls

12 and 13 are externally convex so as to form with the pump envelope 11 a structure of great mechanical strength which will experience Very little deformation upon subjection to pressure. V

The top end wall 13 has a central inlet aperture which receives one appendage of a hollow tubing mechanism 14 having a cross configuration. Two of the remaining open ends of the tubing mechanism 14 are associated with flanges 15 adapted to be connected to systems which it is desired to evacuate. The one remaining open end of the tubing mechanism 14 is closed by a removable stopper 16 as of, for example, rubber which is permanently attached to the tubing 14 through the intermediary of an attaching chain 17. The casing 10 and the bottom end Wall 12 are free of obstructions so as to allow them to be easily submerged in a cooling liquid.

There is provided within the pump envelope 11 a plu- ICC rality of axially elongated U-shaped metallic cooling fins 18 in a generally radial array whereby their free end ridge portions 20 contact the inner periphery of the vacuum pump envelope 11 and their Valley portions 19 extend inwardly toward the central portion of the pump envelope 11. Thus, the cooling fins 18 provide a short high conductance thermal path between the wall and central portion of the elongated envelope 11. The cooling fins 18 are fabricated from a sheet metal having a good thermal conductance such as copper with simple cutting and bending Operations making their tooling extremely simple and inexpensive. A sufficient number of the cooling fins 18 are peripherally compressed within the pump envelope 11 by cone shaped jig assemblies (not shown) centrally inserted from both ends of the envelope 11. This forces the ridge portions 20 of adjacent fins into compressive contact with each other at their free ends and with the inside wall of the envelope 11. The force produced by compressing the cooling fins 13 within the pump envelope 11 maintains them in position for brazing to the inner wall of the envelope 11 and eliminates the necessity of using a more complicated assembly jig. Thus, the cooling fins 18 provide a short high conductance thermal path for distributing cooling between the wall and central portions of the elongated pump envelope 11. It is also possible to reverse the position of the cooling fins 18 by brazing the valley portions 19 to the envelope 11 with the ridge portions 20 extending inwardly therefrom.

A volume of absorbent material 21 such as activated charcoal or molecular sieve as of, for example, zeolite substantially fills the pump envelope 11 and buries the cooling fins 18 which provide cooling therefor.

The distribution of cooling provided by the fins 18 is extremely important because the pumping capacity of a sorption pump is largely dependent upon the temperature and surface area of its absorbent material and because both the absorbent material 21 and the vacuum spaces which exist between the particles of the absorbent material during pumping Operations offer very limited thermal conductance. It would, therefore, be impossible to achieve high pumping capacity without a relatively large volume of well cooled absorbent and impossible to efiiciently cool such large Volumes of absorption material without effective cooling distribution apparatus.

A sorption pump device of the present invention having an inner volume of between l and 2 liters will pump out a 70 liter air system from atmosphere to 29 microns in approximately one hour.

In operation, the sorption pump device of the present invention is placed in an open end container 22 as shown in FIG. 3 and either one or both of the flange members 15 are connected to systems it is desired to evacuate. However, if only one fiange 15 is connected to a vacuum system, the remainng -flange 15 is sealed off with a suitable closure ilange. The container 22 is then filled with a liquid refrigerant 23 such as liquid nitrogen to a level suflicient to cover substantially all of the external envelope 11. The cooling fins 18 brazed to the pump envelope 11 provide good thermal conductivity paths throughout the volume of absorbent material 21 to thereby quickly bring substantially the entire volume of absorbent material to an extremely low temperature equal to that of the liquid refrigerant 22. The refrigerated absorbent material then absorbs gas molecules at a relatively high rate thereby evacuating a vacuum system through the intermediary of the tubing 14. Upon completion of a pumping cycle, the sorption pump is valved of from the vacuum system with a suitable valve (not shown) and the stopper 16 is removed. This releases the pressure within the envelope 11 caused by the absorbed gas evaporation which takes mar/,945

place when the absorbent material 23 reaches higher temperatures. It is the evaporation of gas absorbed by the absorbent material 20 that conditions the sorption pump for another cycle ofpumping which is carried out as described above.v The stopper 16 also serves as a safety valve by automatically disengaging from the pump to release a possibly dangerous pressure buildup within the pump envelope 11. i

The present invention has therefore provided a sorption Vacuum pump which has a large pumping capacity, is extremely elficient, and is relatively inexpensive to tool and assemble;

Since many changes could bemade in the above construction and many apparently widely differing embodiments of this invention could be made without departing from the scope thereof, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

vVWhat is claimed is:

i 1. Arvacuum sorption pump apparatus comprising: a hollow pump casing made of heat conductive, impervious material and having a cylindrical side Wall and top and bottom Walls, said casing adaptedrto be refrigerated by a liquid coolant, said top Wall having a gas inlet aperture, said casing being vacuum tight except for said gas inlet aperture; a plurality of elongated, heat conductive U- shaped fin members disposed in a radial array length- Wise within said casing, said fin members having Valley and ridge portions, said ridge portions being permanently secured to said side wall in good thermal relationship,

said fin members dividing said container into a plm'ality of gas sorbent material receiving compartments disposed on both sides of said fin members; and, gas sorbent material disposed within and substantially tilling each of said compartments and contacting said fin members and casing.

2. Apparatus according to claim 1 wherein said fin members are compressed within said pump casing prior to being permanently secured to said side wall so as to produce a compressive force between their adjacent ridge portions. i

References Cited by the Examiner UNITED STATES PATENTS 1,729,083 9/29 Miller 62-269 XR 2,0l9,356 10/35 Normelli 62-480 2,067,678 1/37 Nesselmann 62-480 2253,90? 8/41 Levine 230-69 2,758,719 8/56 Line -387 XR 2,831,549 4/58 Alpert 55-467 XR 2,925,878 2/60 Spann 55-30 XR 3,116,764 1/64 Jepsen et al.

994,472 4/51 France.

3/39 Netherlands.

REUBTEN FREDMAN, Primary Examiner.

HARRY B. THGRNTON, IOSEPH L. BRANSON, JR.,

. Examrzers.

Claims

1. A VACUUM SORPTION PUMP APPARATUS COMPRISING: A HOLLOW PUMP CASING MADE OF HEAT CONDUCTIVE, IMPERVIOUS MATERIAL AND HAVING A CYLINDRICAL SIDE WALL AND TOP AND BOTTOM WALLS, SAID CASING ADAPTED TO THE REFRIGERATED BY A LIQUID COOLANT, SAID TOP WALL HAVING A GAS INLET APERATURE, SAID CASING BEING VACUUM TIGHT EXCEPT FOR SAID GAS INLET APERTURE; A PLURALITY OF ELONGATED, HEAT CONDUCTIVE USHAPED FIN MEMBERS DISPOSED IN A RADIAL ARRAY LENGTHWISE WITHIN SAID CASING, SAID FIN MEMBERS BEING VALLEY AND RIDGE PORTIONS, SAID RIDGE PORTIONS BEING PERMANENTLY SECURED TO SAID SIDE WALL IN GOOD THERMAL RELATIONSHIP, SAID FIN MEMBERS DIVIDING SAID CONTAINER INTO A PLURALITY OF GAS SORBENT MATERIAL RECEIVING COMPARTMENTS DISPOSED ON BOTH SIDE OF SAID FIN MEMBERS; AND, GAS SORBENT MATERIAL DISPOSED WITHIN AND SUBSTANTIALLY FILLING EACH OF SAID COMPARTMENTS AND CONTACTING SAID FIN MEMBERS AND CASING.