US2774394A

US2774394A - Exhaust system

Info

Publication number: US2774394A
Application number: US242547A
Authority: US
Inventors: Elihu N Morse; Lloyd E Shaw
Original assignee: Columbia Broadcasting System Inc
Current assignee: CBS Broadcasting Inc
Priority date: 1951-08-18
Filing date: 1951-08-18
Publication date: 1956-12-18
Anticipated expiration: 1973-12-18

Description

Dec. 18, 1956 E. N. MORSE ETAL 2,774,394

EXHAUST SYSTEM Filed Aug. 18, 1951 2 Sheets-Sheet 1 PINCH- OFF INVENTORS E LIHU N. MORSE LLQYD'E. SHAW ATTORNEY BYg y g Dec. 18, 1956 E. N. MORSE E-rAL EXHAUST SYSTEM 2 Sheets-Sheet 2 Filed Aug. 18, 1951 l 3/ :UBUEK FIG. 4

INVENTORS Elihu N. Morse y Lloyd E.'Show a). ATTORNEY United States Patent EXHAUST SYSTEM Elihu N. Morse, Swampscott, and Lloyd .E. Shaw, Newburyport, Mass, assignors to Columhia Broadcasting System, Inc, Salem, Mass, a corporation of New York Application August 13, 1951, Serial No. 242,547 10 Claims. er. 141-55 This invention relates in general to exhaust systems and in particular to protective devices for use in such systems.

In the manufacture of electronic tubes as well as in other arts, when it is desired to exhaust the air from a system, pumps of various types are employed. Where the degree or" vacuum desired is not great, a straight mechanical system may be used. To achieve lower pressure a diffusion pump is often inserted between the mechanical pump and the system to be exhausted.

Where high speed rotary exhaust machines are used, it has been found desirable to use an oil diffusion pump with each head or tube carrying element of the machine. The degree of vacuum, and speed of pumping are enhanced by such an arrangement, but several problems are presented when such a system is used. One diificulty encountered is the fouling of the jets of the diffusion pump by particles of glass which often find their way into the system. When breakage occurs, glass fragments are drawn into the pump and improper operation or failure of the pump may result. Even apart from breakage, it sometimes happens that tiny glass particles are present in the tubes being evacuated. Although these particles may be quite firmly lodged within the tubes, the pumping action is often sufficient to draw them from the tubes into the pump with serious results obtaining.

An obvious device for preventing these particles from reaching the pump is a trap of some type placed in the line between the tube and the pump. In the past, such traps usually took the form of a chamber having two lines connected thereto. The input line from the tube was placed below the level of the output line to the pump and the action of gravity was relied upon to prevent glass particles from entering the output line and reaching the pump. Such traps were fairly ettective to remove heavy particles, but were quite inefficient in removing small, light particles which often were borne on the stream of gas being drawn through the chamber into the output line and thence to the pump. A further disadvantage attendant upon the use of such traps was the difliculty involved in dismantling them from the system to remove whatever larger particles may have been deposited within them. i 7

Therefore, it is an object of the present invention to provide a trap for an exhaust system which adequately protects the pump being used in the system.

it is a further object of the present invention to provide tration of the tubulation.

a trap for an exhaust system which operates efi'iciently to remove solid particles of extremely small size and weight.

A still further object of the present invention is to. provide a trap which may be easily dismantled from the system for cleaning purposes when necessary.

In general, the present invention consists in an exhaust system which utilizes a plurality of difl usion pumps, each of which has a substantially Y-shaped structure. This structure resembles the type of coupling which is known as a Y branch, the Y being inverted with the-stem directed upwardlytoward the system being exhausted, the

F 2,774,394 C P ten .18, 1956 2 straight leg leading downwardly to the intake line of a pump and the other or branch leg of the Y leading downwardly toa particle trap at an angle to the stem. Within the stern of the Y atube is centrally supported in communication with the .system being exhausted. This tube is bent to extend into the branch leg of the Y which contains the particle trap, wherein it is also centrally supported. Adjacent to the junction of the stern and branch leg of the Y, but within the branch leg, an upwardly facing aperture is formed in the tube. .Gases being exhausted from the system pass through the tube, out the aperture and thence to the'pump. Particles present in the system also pass through the tube, but by reason of their greater mass continue past the aperture and into a removable container within the trap. For a better understanding of the invention, together with other and further objects, features, and advantages, reference should be made to the following description which is to be read in connection with the accompanying drawings in which:

Fig. 1 is a perspective view of a portion of a rotary exhaust machine;

Fig. 2 is a schematic view of certain elements of the exhaust machine; and

Fig. 3 is a sectional view of the intake stack and trap of the diffusion pump.

Fig. 4 is a view, partially schematic, illustrating working elements of an exhaust machine.

leferringto Fig. l of the drawing there is illustrated in part a rotary exhaust machine. Such machines, as in the present case, usually include a fixed plate having a plurality oi axial openings symmetrically arranged in a circle. A rotatable plate usually similar to the fixed plate is lapped thereto, and a film of oil between the two plates aids in maintaining a vacuum-tight seal when the rotatable plate is moved relative to the fixed plate. The usual method of operation is to have mechanical pumps connected to certain of the openings in the fixed plate and electronic tubes placed in heads which are connected to the openings in the rotatable plate through diffusion pumps. As the rotatable plate is indexed to place the proper openings thereof in register with the openings of the fixed plate being pumped, evacuation of the tubes results.

Referring now to Figs. 2 and 4 of the drawing, there is shown schematically an electronic tube 1 carried in a head 19 on the rotary table 18 of an exhaust machine. The head l includes a length of rubber tubing into which the tubulation of the electronic'tube may be inserted in vacuum tight relationship therewith. A pinch ofi member may then be used to compress a portion or the rubber tubing to form a-closure below the furthest point of pene- Connected to the rubber tubing beneath the pinch off member is a metallic tube 2 which is also maintained in vacuum tight relationship therewith. Metallic tube 2 passes into the intake stack of a diffusion pump 3 which may conveniently be suspendedfrom the rotary table 1% as shown, thus permitting gases to pass from electronic tube 1 into the intake stack when the pinch ofi member is not set to compress the rubber tubing. The outlet line 4; from diffusion pump 3 leads to rotary valve 5 which includes two plates having circularly arranged axial openings and sealed together in the manner discussed hereinabove. For purposes of simand 4. With these openings in. register, gases from the diffusion pump 3 are drawn through rotary valve 5 thence through connecting line 11 to a mechanical pump 10.;

Referring now to Fig 3, there is shown in section a portion of ditfusion pump 3. Tube 2 is inserted in,the intake stack of the pump and a vacuum seal is provided and provides a solid vacuum tight closure.

, of gases therethrough. V

therebetween. The vacuumseal includes an externally threaded male member'13 at the top of the intake stack, cap 14wbich has a central opening which clears tube 2 and has internal threads meshing with those of member 13'. When'cap 14 is tightneddownon' member 13, it bears upon "a washer 15 which has a'circular groove formedin its lower surface. The groove is matched to the end of the intake stack, and contains arubber gasket '17] to maintaina vacuum tight seal between washer 15 and the top of, the intake stackof diifusion pump 3. Washer 15 isi welded to tube 2 and thus a seal-is provided betweentube 2 and the intake stack, the only inlet thereto being by Way of tube2..

' At a point on the intake stack adjacent cap 14 there is shown an additional member- :21 for trapping foreign matter coursing through tube 2. Member 21 is disposed at an angle to the intake stack and tube 2 is bent to enter member 21 at a central location. member 21 is open, but a vacuum seal and cap 22 similar in structure to that on the intake stack closes off the .open end. The cap in this case, however, has no opening .rninates'in an open end spaced from the end of member 21. Adjacent the end of tube 2 is'a barrier formed of a washer 23 welded to tube 2; A cylindrical cou- Tube 2 -ter-' The end of V 1 tainer 24 having an opening formed atone end .and 7 being closed at the other'end slidably fits within mem ber' 21.

23, but disposed at a'point within member 21 an aperture 26 is formed in tube 2.. Thu's,.when diffusion pump 3 is drawing gas throughthe intake stack, foreign matter carried by the stream of gas from electronic tube I mounted above the intake .stack passes through tube 2.

The opening in container 24 is of sufficient diameter to loosely fit over the end of tube 2 but not its position over the end of tube 2. Above barrier washer V 1 At aperture 26, gases are diverted fromtube 2'and' into I member 21, thence to the lower area of diffusion pump.

3, Foreign matter, being ofrgreater massthan thatof the gas molecules, continues past aperture 26 and is col- V lectedin container 24. 7

Obviously, when it is desired to remove foreign matter which collects in container 24, removal of cap 22 is easily efrected permitting access'for removal and cleaning of container 24.

Although the foregoing specification describes the invention as embodied in an exhaust system for electronic tubes, such detailed limitation'of the concepts is only for purposes of illustration of one form the invention may take. General application of the concepts to any a system where it is desired to separate materials of different mass is believed to'be withinthe' scope of the invention, which should be limited only by the following claims. 7 7

What is claimed is: 1. An exhaust system' comprising, a

necting said intake stack to said member, and a trap 7 member to be evacuated, a pump havinganintake stackyaftube con- 60,

connected to said intake stack, said tube penetrating said f trap and terminating in an open end therein, said tube; having a lateral aperture formedtherein preventingthe a passage of .solid material, but'permitting the 'free flow :2. An exhaust system comprisinga imember to be evacuated, a pump havingan intake stack and a tube in a side thereof through which the gaseous portion of said contents is caused to flow, solid'portionsof said said second chamber, solid particles continuing throug contents continuing along said given path of travel through said tube; V a

3. An exhaust system comprising a member to be evacuated, a pump having an intake stack, a hollow t rap having one/end thereof attached to a side of said intake stack and communicating therewith through an aperture formed in the side thereof, a tube connecting said intake stack to said member, said tube being bent at an angle, a first portion of saidtube passing through said intake stack and a second portion thereof entering saidtrap, said 'tube terminating in 'an'open end within said trap and having an aperture formed in a side thereof at 'a point removed from said terrninating open end but within'lsaid trap, and removable means for vacuum sealing the other end of said trap. e

'4. Apparatus for separating solid particles from a stream of gas comprising, a first chamber containing gas at a relatively high pressure and-solid particles mixed therewith, a second chamber containing gas at a relatively low pressure, and a tube for passing said stream of gas from said first chamber to said second chamber,

said tube having an aperture formed in a ,wall thereof and terminating in an open end within said second cham-, ber, pressure within said second chamber being lower adjacent said aperture than at said open end, said stream of gas in said tube passing. through said aperture and communication with said first chamber, and ,extending' we downwardly through said secondchamber, the otheropen end of said tube being disposedwithiusaid branch chamber, said tube having an upwardly facing aperture formed f in a wall thereof at-a point within saidbranch chamber.

adjacent said second chamber, whereby said stream'of gas Passingthrough said tube is diverted through said aperture into said second chamber, solid particles con:

tinuing through said other open end of said tube into said branch chamber. 1

6. Apparatus for separating solid particles from a' s'tream of gas comprising, a first chamber containing gas ata relatively high pressure and solid particles mixed therewith, a'second chamber disposed beneath saidfirst chamber, a pump for maintaining said second chamber." at a relatively low pressure, a branch chamber having one .end connected to said second chamber and depending downwardly therefrom, an open-ended tube'having f 'oneend thereof incommunication with said first chamber "and, extending downwardly through said s'econd ch'amber' intosaid branch chamber, saidtube having an upwardly facingaperture formed in a wall thereof at a point within said branch chamber, adjacent, said second chamber, ,a

container loosely fitte'd'over thev other end of said tube within said branch chamber, aremovable cap for-vacuum sealing the other end of, saidbranch chamber, said cap maintaining said container in position overrisaid'other end offsaidtube whereby said stream of gas passing through said tube is diverted through said aperture into saidtube into saidcontainer. V V r r I 7. Apparatus for removing solid matter from the intake stack of a diffusion pump comprising, a tube vacuumsealed in said intake stack' for permitting the entry of "gases thereto, 'a'trap having one endthereof joined tofth'e tside of said intake stack'and communicating with the interior thereof by'means of an aperture formed in a wall thereof, the longitudinal axis be saidi'trap 'being at an angle to that of said' intake stackj saidtube being bent through'an'angle such thata portion thereof is coaxial with said trap, .a container loosely fitted within said trap e Ji and having an open end enclosing one end of said tube, and a removable cap for vacuum sealing the other end of said trap and for retaining said container within said trap, said tube having an aperture formed in a wall thereof whereby gases passing through said tube reach said intake stack through said aperture and solid foreign matter proceeds through said tube and into said container.

8. Apparatus for filtering solid matter from the intake stack of a diffusion pump comprising, a tube sealed in said intake stack for permitting the entry of gases thereto, a trap having one end thereof joined to the side of said intake stack and communicating with the interior thereof by means of an aperture formed in a wall thereof, the longitudinal axis of said trap being at a first angle to that of said intake stack, such that said trap depends downwardly therefrom, said tube being bent at a second angle equal to said first angle such that a first portion of said tube is coaxial with said intake stack and a second portion of said tube is coaxial with said trap, a barrier member of diameter larger than that of said tube welded thereto at a point within said trap, an upwardly facing aperture being formed in the wall of said tube above said barrier member but within said trap, a container having an open end of diameter larger than that of said barrier member loosely fitted within said trap with the open end thereof enclosing the open end of said tube and abutting said barrier member, and a removable cap for vacuum sealing the other end of said trap and for retaining said container in position whereby gases passing through said tube are diverted through said aperture formed therein and foreign solid matter continues through said tube into said container.

9. An exhaust system comprising, a rotary exhaust machine including a first rotatable plate having a plurality of axial openings formed therein symmetrically disposed in a circle adjacent the periphery thereof, a second fixed plate disposed beneath said first plate and having a similar plurality of axial openings formed therein about and adjacent the periphery thereof, said openings in said first plate being in register with those of said second plate, a plurality of diffusion pumps each having an intake stack and an outlet line, means for connecting each of said outlet lines to one of said openings in said first plate, a rotary table having a similar plurality of heads and adapted to rotate with said first plate, a similar plurality of tubes each connecting one of said heads to one of said intake stacks and each being bent at an angle to the longitudinal axes thereof at a point remote from the point of entry, a downwardly depending trap member having one end thereof connected to the side of said intake stack through an aperture formed therein, said tube entering said trap member and terminating in an open end adjacent the other end of said trap member, said tube having an upwardly facing aperture formed in a wall thereof at a point adjacent the bend in said tube between said aperture and said terminating open end, whereby gases issuing from said head are drawn through said tube and out said aperture to the intake stack of said diffusion pump, solid particles being carried through the terminating open end of said tube and deposited in said other end of said trap member.

10. An exhaust system comprising, a rotary exhaust machine having a rotary table having a plurality of spaced heads disposed about and adjacent the periphery thereof, a first rotatable plate having a similar plurality of symmetrically arrayed axial openings formed therein, a similar plurality of diffusion pumps connected between said heads and said openings in said first plate, a second fixed plate disposed beneath said first plate in vacuum tight relationship therewith and having a similar plurality of symmetrically arrayed axial openings formed therein, said openings in said first plate being in register with those of said second plate, means for indexing said first plate relative to said second plate to bring consecutive ones of said openings in said first plate into register with those of said second plate, said plurality of diffusion pumps including intake stacks disposed beneath said rotary table, means for separately connecting each of said intake stacks to one of said spaced heads of said rotary table, said lastmentioned means each including a tube communicating with one of said plurality of openings in said second plate, each of said intake stacks having an aperture formed in a side thereof, hollow open ended members of cross-sectional dimensions substantially similar to those of said intake stacks, one end of each of said hollow members being connected at an angle to each of said intake stacks and depending downwardly therefrom, the open end of each of said hollow members and the aperture of each of said intake stacks forming a mutual opening therebetween, said tube being bent to enter said hollow member at a central point and to follow the longitudinal axis thereof, said tube terminating in an open end adjacent the other end of said hollow member, a cap threadably attached to said other end of said hollow member in vacuum-tight relationship therewith, a barrier washer attached to said tube at a point adjacent the termination thereof, said tube having an upwardly facing aperture formed in a wall thereof at a point above said barrier washer but within said hollow member, whereby gases issuing from said heads are pumped through said tube and out said aperture to the intake stack of said difiusion pump, particles of foreign matter being carried through said tube and deposited in said hollow member adjacent said cap.

References Cited in the file of this patent UNITED STATES PATENTS 430,444 Smith June 17, 1890 1,461,173 Bennett July 10, 1923 2,162,209 Trutner June 13, 1939 2,254,905 Mullan Sept. 2, 1941 2,265,381 Molloy Dec. 9, 1941 2,542,636 De Groat -a Feb. 20, 1951 2,565,298 De Groat Aug. 21, 1951