US2634894A - Powder handling device with protected driving mechanism - Google Patents

Description

April 14, 1953 P. E. FISCHER ETAL 2,634,894

POWDER HANDLING DEVICE WITH PROTECTED "DRIVING MECHANISM Filed April 5, 1948 4 Sheets-Sheet l 7e 44 76 s3 7 a2 79 65 Z i 23 40 23 I 42 6 45 52 1 I 66 4| 5| 96 5 73 6| 54 53 68 69 l i 267 57 I mwmronsx- 56 59 PAUL E. FISCHER 58 MORTIMER a. STURDEVANT By MK 5M April 14, 1953 P. E. FISCHER ET AL POWDER HANDLING DEVICE'W ITH PROTECTED DRIVING MECHANISM Filed April 5, 1948 4 Sheets-Sheet 2.

IN VENTOR5.'-

PAUL E. FISCHER MORTIMER B. STURDEVANT ATTY.

April 14, 1953 P. E. FISCHER ET AL POWDER HANDLING DEVICE WITH PROTECTED DRIVING MECHANISM Filed April 5, 1948 4 Sheets-Sheet 3 mac IN VE/VTORSI- PAUL E. FISCHER MORTIMER B. STURDEVANT ATTY.

April 14, 1953 P. E. FISCHER ET AL Filed April 5, 1948 4 Sheets-Sheet 4 //VVENTOR$.'-

PAUL E. FISCHER MORTIMER B. STURDEVANT 72a; a M

JTTY.

Patented Apr. 14, 1953 POWDER HANDLING DEVICE WITH PRO TECTED DRIVING MECHANISM Paul E. Fischer and Mortimer B. Sturdevant, Minneapolis, Minn., assignors to General Mills, Inc., a corporation of Delaware Application April 5, 1948, Serial No. 19,104

20 Claims. (01. 226-96) The present invention relates to filling machines and more particularly to improved supporting means for containers to be filled, and to improved means for increasing the life of the machine parts.

Many devices are known which include a relatively movable filling head and support, between which a container is positioned for a filling operation. In high speed machines of this type a number of such filling heads and supporting plates are radially positioned with respect to a central vertical axis and are rotatable around said axis during the filling operation. Various methods have been proposedfor production of the necessary relative movement between the filling head and support, and the use of air pressure to cause this movement is well known. The use of air pressure has the advantage that the relative distance between the filling head and support is limited by the size of the container, and the air pressure permits adjustment of this distance to containers of slightly different dimensions. However, the use of air pressure in known devices of this type often increases the dust problem, particularly in the filling of powdered materials.

One difficulty in filling machines of this general type and particularly in machines which are to be utilized for the handling of finely powdered materials is that the material to be filled will penetrate the various mechanical parts of the machine in the form of a fine dust. The abrasive action of this dust seriously hortens the life of the various moving parts of the usual driving mechanism and results in increased maintenance and repair costs. The use of air pressure in known devices of this type adds to the dust problem.

With these difficulties of the prior devices in mind, it is one object of the present invention to provide an improved pressure-actuated mechanism for production of relative movement between the filling head and supporting platform of a filling machine.

Another object is the provision of a filling machine in which the driving mechanism is protected against penetration of dust.

A further object is the provision of a filling machine in which the driving mechanism is enclosed in a housing wherein the pressure is higher than that outside of the housing.

Still another object is the provision of a filling machine in which the driving mechanism is enclosed in a housing and in which the pressureactuated lifting mechanism for a container support is operatively connected to said housing for maintenance of increased pressure within the housing 'due to the exhaust from the pressureactuated mechanism.

Other objects and advantages will be apparent from the following specification in which a detailed description of a preferred embodiment of the invention is given.

In the drawings which form a part of this specification, and in which like reference characters indicate like parts,

Figure 1 is a partial sectional view of a filling machine embodying features of the present invention.

Fig. 2 is a sectional view on the line 2-2 of Fig. 1. Y Fig. 3 is an enlarged sectional view of a portion of the mechanism of Fig. 1.

Fig. 4 isa partial perspective view of the sealing means shown in Fig. 3.

Fig. 5 is a partial sectional view of the rotatable supporting plate of the filling machine of Fig. 1.

Fig. 6 is a partial perspective view of the base of the machine of Fig. 1, certain portions being broken away for clearness.

Fig. 7 is a top view of the base of the machine, certain portions being shown in section and others in dotted outline for the sake of clarity.

Fig. 8 is a sectional view on the line 8-8 of Fig. 7, with certain portions broken away to show details of the shaft seal.

Fig. 9 is a partial sectional view of a modified sealing device according to the invention, and

Fig. 10 is a partial perspective view of the base of the machine of Fig. 1 which shows details of the guide and limiting means for the container supports.

As shown in Fig. 1 the filling machine is provided with a base 19 which has a central cylindrical supporting column or post 20 rigidly mounted thereon. A suitable thrust bearing 2| on this central support 20 carries the weight of a filling unit. The various parts of this filling unit are carried by a substantially circular supporting member or plate 22 which has a central bearing portion 23 rotatably mounted on the post 20.

A supporting frame 24 on this plate 22 carries an upper filling head support 25. Above this upper support or plate 25 is a suitable hopper 2G for the material to be filled. Plate 25 also carries a plurality of filling heads 21, each of which has a cylindrical central depending projection 28 adapted to be inserted in the top of a container by air passages 32 to a suitable pipe or hose 331' connected to air pressure control means of any known type; r

Since the particular type of filling head and the pressure conditions under which the container is to be filled form no part of the present invention and since the present invention may be utilized advantageously with any knowntypes of filling units, no detailed description of the filling operation or of the filling head construction need be given.

'- Ilfdesired; the filling head may carry. a suitable shroud35 having'a gasket. 35 at its lower end for: cooperation with-the supporting'plate 3'? for container 29.

It is customary in these filling units to provide, for relative movement between the filling head2'i. and the supporting plate 3?. Depending upon the type of unit, .one of these members may remain stationary while the other moves toward and 'away'from the stationary'member, or in some cases both members may be movable." Thus the fillingunit'includes at least one member movably mountedon the rotatable support 22.

For purposes of: illustration we have shown a filling unit in which the filling heads 2? remain relatively fixed in vertical position .whilethe supporting plate 37 is. reciprocated vertically to raise andhold the. containerf29. against the filling head. It will be understood that while the filling head 21! is not movable vertically; it does rotate" around the central vertical axis of the machine by reason of the mounting of bearing portion '23 on the central po-st'2i To provide the necessary vertical movement of plate 31, We have attached theplateto' the upperend of a hollow' cylinder 38. This cylinder is adapted to slide vertically on a fixed piston 39.; Piston 39 is bolted to a supporting plate 4fl-byimeansof a nut-4i and this plate lil is fastened to the outer portion 42- of the main circular supporting plate 22 of the rotatable filling unit. i

A vertical guide rod is is provided for each lifting device and is fastened tothe rotatable support 22 by means of threads 45. Rollers Ill and 48 (Fig. 2) are mounted on the vertically slidable cylinder 38 and engage opposite sides of the vertical guide All to steady the cylinder during its vertical reciprocation. Top bars 45 connect and reinforce adjacent rods 44.

To actuate the lifting mechanism, fixed piston 39 is provided with a central pasageway 49, the upper end of which communicates with the hollow internal chamber 59 of cylinder t8. The lower end or passage 49 opens into a small recess or air chamber 5| in main support 22. An air tube or hose 52 connects the chamber 5| to an annular valve member 53- which surrounds central post and is carried by the rotatable plate 22. This annular valve member 53 has a horizontal lower face provided with an opening 55 connected to the air tube 52. A valve'54'may be provided in the air line 52 for control purposes;

The rotatable annular valve member 53 00- operates with a fixed annular valve member 55 which has a horizontal upper surface 51 provided with a pressure slot 58 connected to a pipe 59 for attachment to a suitable source of compressed aira The fixed annular valve member 56 likewise has an exhaust slot 6! communicating with a suitable exhaust pipe 52. The arrangement of i-the annular valve member 56 will be clear from reference toFig. 6. Thus as the rotatable supporting plate 22'revolves around the central post 21 the air control opening 55 corresponding to a given cylinder 38 will communicate alternately 1 with the pressure valve slot 5% and the exhaust valve'slot 6| When this opening is in communication with the pressure slot 55, the compressed air will be admitted through the pipe 52, chamber 5i, and passage its to the interior 50 of cylinder 33 and will thus lift the cylinder and its'supporting plate 37 to position the. container 22 against the filling. head 21. Similarly when the rotatable valve opening55 is in alignment with the exhaust slot 6!, the pressure within cylinder 38 will be relieved through exhaustpas sage, E2 and the lifting plate 31 will be permitted to drop of its own weight.

In order to prevent abrasion of the piston and cylinder by the action of dust or particles of the materialbeing filled; a bellows 63S isprovided, which encloses'the space between the bottom of the cylinder 38 and thetop of. supporting-bracket 36. This bellows 63 is:.fastened to the lower end of the cylinder by a clamp. 64 and-is similarly fastened-to. a cylindrical-shoulder on member '43 by a'clamp. 55; Thebellows or sleeve'63 is of the expansiblefoldin'g type and can thus lengthen and. shorten as' required to accommodate theraisingTand lowering.ofthe cylinder 38 and maintain a protectivecover at all times around the otherwise. exposed portion of fixed piston 39. T

To permit changes inthe efiective length of the bellows: during movement'of the cylinder without rupture of the bellows by increase of pressure as the cylinder is lowered, a bleed pas sage 66:.is providedin mernbers 40 and-42 which communicates at its upper end'with the space inside the bellows 83 and outside piston 39'. The lower end of this passage 56 opens at a point on the bottom of the peripheralportion 42 of circular supporting plate 22 A housings? is provided on base I9 andis designedto form asubstantially air-tight enclosure for the driving mechanism of the machine. This housing is provided withopenings, only to the extent required to permit passage of the connecting members which operate the filling and conveying" mechanismirom the'enclosed driving mechanism. The top portion 68 0f housing 61 has a substantially-circular opening fifiiwhichis concentric with the supporting post 20 at the centerof the base. An annular seat-1 ing member H is fastened at theedge of open ing" 69 by bolts 72 (Fig. 3)- and-this annular member is provided with a seat "l3 for coopera-. tion with a sealing member i l mounted on the peripheral portion 42- of circular supporting plate 22. As shown in Figs. 3 and 4, this sealing member! is made of rubber or other flexible air-tight material and is fastened against the beveled edge 75 ofperipheral-portion 42 "by a series of spring clamp's l6 held in place by bolts. 11. These spring clamps'it -are provided with two spring arms '78 and ls which have offset.

ends 8| and 82 hearing against the edge of gasket [4. Thus the resilience of the spring arms 18 and 79 will hold the outer edge of asket I4 firmly against seat I3 of the annular member 1| on the top 68 of casing 61. The other or inner edge of gasket I4, which is designated as 83 in Fig. 3, will be held tightly against the beveled portion 75 by the inner end of the spring clamp "I6 and by bolt 11.

Since the circular supporting plate 22 is of solid construction, this plate with its gasket 14 will serve as a closure for the opening 69 in the top of casing 6! and will provide a construction in which all portions of the mechanism within the confines of housing 61 and plate 22 are substantially protected from dust and from particles of the material being filled.

With reference to Figs. 6, 7, and 8 the driving mechanism includes a motor 84 mounted within casing 61 and having a speed control wheel 80 (Fig. 7) which projects externally from the casing for manipulation by the operator. A drive pulley 85 on the motor shaft is connected by belts 86 to a driven pulley 81 on horizontal shaft 86 of a gear unit 89. This gear unit is also inside the base housing 61 and includes a vertical shaft I which carries a driving pinion 90. Pinion 90 meshes with a larger gear 9| on vertical shaft 92. This shaft carries at its upper end a suitable star wheel or transfer device |29 (Fig. 10) which shifts the containers from the supply conveyor |3| onto the lifting plates 31 of the rotatable portion of the machine in known manner. By the connections just described the motor 84 drives this transfer wheel I29 at the appropriate speed.

Gear 9| on shaft 92 also meshes with the large annular ring gear 93 which is carried by annular bracket 94 fastened to the circular sup porting plate 22 at 96. Slots 91 in member 94 permit passage of the tubes 52 which control the pressure in cylinders 38. Thus as shaft 92 and. gear 9| are rotated through their connections with the driving motor 84, gear 9| will in turn drive the ring gear 93 to rotate the supporting plate 22 and bring the lifting plates and cylinders successively into position to receive a container from the transfer wheel I29.

A similar transfer wheel I30 is carried by a shaft 99 and is utilized to move the filled containers from the lifting plates of the rotatable mechanism onto the discharge conveyor I32 (Fig. 10). Shaft 99 of discharge wheel I30 carries a gear 98 which is driven directly from the ring gear 93 onrotatable supporting plate 22. The

size of the gears and the,,number of teeth involved are chosen to provide the desired coordination between the linear circular speed of the supporting plates and the respective feeding and discharge wheels I29 and I30.

As shown in Fig. 8, sealing means are provided to prevent dust and particles of material from entering the housing 61 where shafts 92 and 99 project through the upper hbusing plate 68. Thus the plate 68 has an opening I0| large enough to accommodate the shaft 99. A bearing and sealing member I02 is mounted on the plate 68 around the opening |0| and includes an annular channel I03 in which a resilient sealing gasket I04 is located. Bolts I05 clamp member I02 to plate 68. A dust shield or hood I06 is fastened to shaft 99 by screws I01 and includes a depending skirt portion which overlaps the edge of the bearing member I02 as shown to assist in the exclusion of dust and dirt from 7 5.

the, mechanism housing. j Asimilar. sealing ar rangement is provided for shaft 92.

As described above, housing 61 in which the driving mechanism is mounted is of substantially air-tight construction and is open only at the points where the shafts 92 and 99 project and also at the circular top portion which is covered by rotatable supporting plate 22 of the filling head mechanism. The presence of the various sealing gaskets further resists penetration of particles to the interior of the housing and thus the vital mechanical parts which are contained in that housing are protected against abrasion and undue wear. It should be noted that a suitable sealing arrangement may be provided at the point where the supporting post 20 projects through the central bearing portion 23 of plate 22. Or a suitable cap on member 22 may completely enclose the upper end of post 20. This additional sealing arrangement is provided in the present case by means of such a cap and includes the supporting frame or side housing 24 and the upper supporting plate 25. Thus, all portions of the mechanism are protected and the chances of penetration by small particles of material are reduced.

We have found, however, that even with all the precautions indicated above such as the provision of sealing gaskets at all openings, there is still a tendency for the very fine particles of powdered material or dust to work their way into the housing along the shafts and through the bearings which surround these shafts. These particles still have the effect of shortening the life of the working parts. We have found that this difficulty can be overcome by creation of a pressure differential between the inside and the outside of housing 61. Thus We provide means for introducing air or other gas to the interior of housing 61. This extra admitted air tends to increase the pressure within housing 61 to a point slightly above the external atmospheric pressure around the housing. Thus there is a tendency for air to leak outwardly through any openings in housing 61. For example, air tends to be forced outwardly between the sealing gasket I4 and the annular seat I3 in the top 68 of housing 61. Similarly, air tends to move outwardly along shafts 92 and 99. This tendency for the air to escape from the housing 6,! effectively prevents penetration of dust and powder to the interior of the housing even under long and continuous use. Particles which do attempt to penetrate the housing, for example, along shafts 92 and 99, are met by the outward flow of air and are carried away and thus excluded from the housing.

While it would be possible to provide a separate source of air pressure which would serve the sole purpose of maintaining the desired pressure differential between the inside and the outside of the housing 61, we have found it particularly economical and advantageous to utilize the air which is exhausted from the liftin cylinders 38. Thus the exhaust passage 62 which communicates with the exhaust slot 6| in annular valve '56 opens directly to the interior of housing 61. In other words, compressed air is brought into the housing 61 and fed directly to stationary valve member;56 through connection 59. The compressed air then passes to each of the lifting cylinders in turn as these cylinders rotate to that portion of their circular path in which the corresponding valve openings 53 coincide with some portion of pressure slot 58,

ass -s94 i; e., between points I53 21116154 (Fig. 6). During this portion of the" travel of the respective oylin dersfthey will be lifted as a result or the increased pressure in chambers 50. Further rotation of the plate 22 carries the valve opening of a given cylinder around to a point coinciding with a portion of exhaust Slot 6|; Through the portion of travel which corresponds to slot GI the chamber 55 is effectively connected to exhaust pipe 62 and mus t the interior of housing so that the cylinder 38 may drop of its own weight and the air which was compressed in chamber 50 may escape into the interior of housing 51. I r r In the present machine; with eight filling heads; at least one of the cylinders 38 will be in exhaust position over some portion of slot BI at any given time, so that there will be a constant how of air into the casing E'E through eiihaust 62.

If the various gaskets and sealing devices were held too rigidly in place there would be atendency for pressure within the housing 61 to build up to a point where there might be some inter ference With the lowering of cylinders 38. Also the gaskets would wear unnecessarily. This problem is avoided by use of a resiliently mount ed. sealing member such as gasket 14 previously described. Since this sealing gasket overlaps the annular seat on the outside of the casing, any excess pressure which tends to build up within the casing can be relieved automatically by flexing the gasket outwardly against the tension of the spring arms which hold it. Also, as described above, the seal should permit a slight but definiteoutward flow of air from the interior-of casing 6 7, so that dust and particles of powder will be carried away from the sealing and bear= ing surfaces and will not wear out such surfaces or penetrate inside thecasing.

Another important feature of the present arrangement is the location of bleed passage 65 for the bellows 63. Since the lower end of this passage opens into the interior of casing 61, the bellows 63 will have the same benefits of increased pressure and absence of dust as the other internal working parts. Wear and abrasion of cylinder 38 and piston '39 are thereby reduced.

In Fig. 9 an alternate arrangement for this main sealing gasket has been Shown. .In this embodiment of the invention the rotatalfl'es'up-v porting plate of the lifting mechanism is designated as IE9 and is provided With an anhular.

shoulder iii! at its outer edge. A flexible gasket member HI is fastened at its inner edge to. shoulder III) by screws IE2. This gasket niefn' ber H I may be of fabric which is ileirible and slightly porous. An annular metallic ring I I3 is carried by the outer edge of flexible gasket III and is fastened to thegasket by screws H4 and washers H5. This annular member H3 has a horizontal surface H6 at its inner edge and a depending skirt II? at its outer edge. The flat portion H6 is adapted to engage andseat on a strip H8 of suitable sealing materia sum as felt, which is carried in a groove I I9 in the pro- J'ectin rim I 20 of annular seat I2I. Member I2I is fastened tothe top 68 of casing 67 by bolts I22 and. provides the necessary gasket seat at the edge of the. opening.

In theconstruction just described, the necessary sealing efiect between member II 3 and strip Ii 8 will be obtained as a result of the Weight of the metallic ring. II3.- The flexible gasket member III will permit vertical movement of gasket ring H3 t'o aecoiiimodate the ring to the sealing strip H8. Also this flexibility in the support of ring II3permits movementof the ring to relieve the internal pressure if such pres sure tends to build up to a higher point thanis desirable. Further relief of the pressure may be obtained by reason of the porosity of the material from which the flexible gasket support is made.

In connection with the pressureoperated cylinders 38 for the supporting platforms of the filling mechanism, we have provided conventional guide and limitin devices which insure smooth operation of the'rnechanism and prevent jamming of the machine. As shown in Fig. 10 guide or stop members I24 and I25 are provided in the form of rails which extend in a ciroular path co-axially with the a'xis of rotation of the main supporting plate 22 or the unit Rail I24 is mounted on supports I26 and I2 fastened to the top 68 of casing 51. Rail I25 is carried by integral legs V28 which are likewise fastened to the top of the lower casing. These rails to operate with rollers I34, one of which is provided.

on eaoh lifting cylinder 38 as 1 and 2.

Rail I24 serves as an upper limit and guide for the rollers I34 during that portion of the rotation of the cylinders in which compressed air is being admitted through the valve slot 58. Thus when the pressure is first increased inside a given cylinder 33, it will be raised uiitil it's roller I34 engages the bottom surface of rail I24. As the machine rotates, the roller I34 will travel along the lower surface I35, which will prevent lifting of the cylinder 38 and its associated platform shown in Figs.

' until the roller reaches the upwardly inclined end :36 of rail I24; At this me since pressure has been increased within the cylinder, the sup: portihgp-latform 'will be raised smoothly to the extent permitted by the slope of portion I36.

The second rail member I25 is provided with a substantially horizontal top surface I37. This horizontal section extends opposite the firstportion of exhaust slot 6I, so that when the pressure is relieved in the normal operation of the machine, the cylinder roller I34 engages the top of h'ori-1 zont'al surface 31. The end portion of rail I25 in the direction of rotation of the machine slopes downwardly as indicated at I33 and terminates in a lowered horizontal sectionI39. Since pressure withinthe cylinder has been relieved by the time roller I34 reaches the end of the horizontal rail portion I31, the weight of the cylinder and associatedparts will cause it to drop smoothly as roller I34 reaches the sloping portion I38 and follows the slopedownwardly. Thus in normal operation the cylinder 38 and its supporting platrorm will'be'lowe'red just prior to the point at which the discharge Wheel I39 is. to ehgagearid remove'the container from a particular supporting platform. I V A safety device is provided to stop the machine in. the event that the cylinder 33 Should become jammedin its upper position. This safety device includes a pivoted lever arm I42 which is rotatably mounted at I43 to the end of rail I24. Should a container support become jammed in the upper position, the associated roller I would engage'the lower surface I44 of this'safety lever I42 and would tilt the lever in a counterclockwise direction Withrefernoe to Fig. 10. A crank arm I45 on lever 142 has a slot in'whioh a connecting rod I47 is .pivotally attached at 146. The connecun' rod I41 is operativlyconnected to the arm s or a suitable switch I49. Switch I49 com tr'msthe operation or the main driving motor iii" '9 by means of wires I50 and Il.' The particular circuit by which this is accomplished is well known in the art and is omitted for clearness.

From the foregoing description, it is apparent that we have provided an improved pressure actuated mechanism for causing the necessary relative movement between the filling head and container support of a filling machine. While this mechanism has been shown and described in connection with a movable supporting platform, the same principles can be applied to a device in which the platform is stationary and the filling head is movable.

We have also provided means for enclosing the mechanism in a protective housing and maintaining a pressure difierential between the inside and outside of the housing. The pressure in the housing is preferably maintained by connections with the pressure actuated container supports. The use of this improved arrangement of the housing and the pressure-operated supporting platforms ofiers definite advantages in commercial operation at high speed and is particularly desirable since it permits the combination of a practical pressure-operated lifting mechanism with a protective casing in which a pressure differential is maintained with respect to the surrounding atmosphere to exclude dust, dirt and particles of the material being filled.

Obviously many variations in the specific details of construction of the parts and the manner in which they engage each other to perform the specific functions may be made by persons skilled in this field. It is therefore intended that this invention shall include all such modifications, changes, and improvements as fall within the spirit and scope of the attached claims.

Now, therefore, we claim:

1. A filling machine comprising driving mechanism, a housing enclosing said mechanism and having an opening, a movable portion of the mechanism extending through the opening, a filling unit outside said housing connected to the movable portion, pressure responsive sealing means exhausting air from the housing around said portion, and means for introducing air under pressure within the housing in an amount insuring exhaust operation of the sealing means during each operation of the filling unit.

2. A filling machine comprising a relatively movable filling head and support for a container to be filled, pressure-operated means for relative movement of the head and support and including a source of pressure, driving mechanism for the machine, a housing enclosing the driving mechanism with the filling head outside the housing, and an air connection between the source of pressure and the interior of the housing for increasing the pressure in which the driving mechanism operates within the housing above the pressur in the vicinity of the filling head.

3. A filling machine comprising a base, a support rotatably mounted on the base, a filling unit having at least one member movably mounted on the support,vmeans on the support for causing movement of the member including a pressure cylinder and piston, one of which is connected to the member, the piston having an exhaust opening communicating with the interior of the cylinder, driving mechanism mounted on the base, a housing enclosing the mechanism, and means connecting the piston exhaust opening to the interior of the housing for maintaining a pressure differential between the inside and outside of the housing.

4; A device for handling powdered materials comprising driving mechanism, a housing enclosing the mechanism and having an opening, a powder handling unit outside the housing, a driving connection between the mechanism and the unit including a movable driving member extending from the inside to theoutside of the housing through the opening, means continuously introducing a pressure medium inside the housing and thereby maintaining a higher pressure inside the housing than in the vicinity ofsaid powder handling unit, and sealing means between the housing and movable member permitting continuous controlled escape of the pressure medium through the opening around the movable driving member during movement of the member, thereby continuously carrying away from the housing any powder particles tending to, enter the housing from said powder handling unit through said opening and along said driving member.

5. A device according to claim 4 in which the sealing means is movable as a resultof predetermined pressure within the housing to provide a controlled flow of air from the inside to the outside of the housing.

6. A device according to claim 5 in which the sealing means includes a flexible annular sealing strip, and spring means resiliently holding said strip in sealing position.

'7. A device according to claim 6 in which the sealing means includes a flexible annular sealing strip, and a rigid annular sealing ring carried by from the inside to the outside of the housingthrough the opening, means introducing a fluid under increased pressure within the housing during each operation of the unit, and deformable sealing means at the-opening for controlled relief of pressure through escape of said fluid between the housing and the movable driving connection member.

10. A filling machine comprising a base, a gas tight housing on the base having a top opening, a supporting plate rotatably mounted on the base and substantially closing the opening, a relatively movable piston and cylinder one of which is fixed to the plate, an expandable bellows enclosing the exposed portion of the piston and spaced therefrom to provide an air tight chamber, said plate having an air passage connecting the chamber and the interior of the housing.

11. A filling machine comprising a base, a gas tight housing on the base having a top opening, a supporting plate rotatably mounted on the base and having sealing means substantially closing the opening, a filling unit mounted on the plate and including a filling head member and a container support member one of which is movable with respect to the other, pressure actuated mechanism for the movable member including a piston and cylinder one of which is fixed to the plate and the other of which is fixed to the movable member, and means for exhausting the cylinder into the interior of the housing.

12. A machine according to claim 11 having 11 an expandable bellows fastened to, the cylinder and enclosing the, exposed portion 01 the piston to form a closed air chamber, and an air connection between the interiorof the chamber and the interior of the housing.-

13. A filling machine comprising a base, a gas tight housing on the base having a top. opening, a supporting plate rotatably mounted on the base and substantially closing the opening, a fillin unit mounted on the plate including a piston fixed to the plate, a cylinder reciprocable on the. piston and a container support. fastened to the cylinder, and valve means for selective connection of the cylinder to the interior of the housing to maintain a pressure difierential between the inside and outside of the casing.

14. A machine according to claim 13 having a bellows enclosing the piston and fixed to the cylinder and plate to form an air tight chamber around the piston, the plate having an air pas: sage between the chamber and the interiorof the housing.

15. A device for handling powdered materials comprising driving mechanism, a. housing enclosing the mechanism and having an opening, a powder handling unit outside the housing, a connection between the mechanism and the. unit in-. cluding a movable member extend ng from the inside to the outside of the housing through the opening, means introducing a pressure medium into the housing during each operation of the powder handling unit, and means exhausting the pressure medium from the housing through the opening around said member.

16. A device for handling powdered materials comprising driving mechanism, a housing enclos ing the mechanism and having an opening, a powder handling unit outside the housing, a connection between the mechanism and the unit in cluding a movable member extending from the inside to the outside of the housing through the opening, means constantly introducing air under pressure into the housing during operation of the powder handling unit and resiliently movable sealing means between the housing and movable member exhausting the excess air from the housing through the opening around said member.

17. A filling machine comprising a base, a gas tight housing on the base having a top opening, a supporting plate rotatably mounted on the base and substantially closing the opening, a plurality of filling units mounted on the plate and each including relatively movable filling head and container support members and pressure actuated mechanism for causing such relative movement, and rotary valve means within the housing including stationary annular pressure and exhaust slots located around the axis of rotation of the plate, means rotatable with the plate and com nectin each pressure actuated mechanism successively with the pressure and exhaust slots dining r ation of the plate, means for connectin 12 the pressureslot to a source; of flui under pres sure, and the exhaustslot discharging directly to the interior of the. housin 18. A filling machine, comprisin a base, a gas tight housing on the base havin a p p nin a supporting plate, rotatably mounted on the base and. substantially closingthe opening, a plurality of filling units mounted on the plate and each including relatively movable filling head and container support members and pressure actuated mechanism for causing such relative movement, and ro ry v lvev means Within he h using in.- cluding pressure and exhaust slots with which h. pressure mechan sm is connected su sively during rotation Qf the plate, the exhaust slot: communicating directly with the interior of the housing.

19- A fi-l-ling ma hine comprising a base, a gas tight housing on the, base having a to opening, a supportin plate. ro at y mounted on the bas and having sealing means substantially closing the, opening, a fillmgunit mounted on the plate and including a, filling head member and a cone tainer support member one of which is movable with respect to th other, pressure actuated mechanism for the. mo a le m b l ng a piston an c linder one ofwhich is p r tiv y connected to the movable member, and means for exhausting the cylinder into the interior of the housing.

29. A device, for handling pcw r ma r als c mpris n drivins'me 21.. a hous c sing the mech nism and. ing. an op nin a powder handlin u it: outside the h sing a dr v ing connection between .6. mec m an unit includ ng a movab e driving member ext ndin from the inside to. the utsi e of the housin through said opening, means. maintaining a rela tively higher pressure inside the housing than in the vicinity of the p wder han l ng unit dur n operation of the latter, and means relieving the higher pressure from the hqusing; through the opening around said driving member during op eration of the powder handling unit, thereby carrying away from the housing and driving mechanism any powder particles which might otherwise escape from the powder handling unit and enter the housing through said opening and along said driving member. I

PAUL rise-nee. MORTIMER B.. STURDEVANT.

References Cited in the. file of this patent UNITED STATES PATENTS Number Name Date 1,000,971 Bastian Aug. 15, 1911 1,750,818 Sauveur Mar. 18, 1930 2,223,480 Darling Dec. 3, 1940 2,380,984 M'oeller Aug. 7, 1945 2,381,764 McFarland, Jr. Adg. 7, 1 45'

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