US2158717A - Vacuum cleaner - Google Patents

Description

May 16, 1939. c. A. BROCK 2,158,717

VACUUM CLEANER Filed Dec. 18, 1935 3 Sheets-Sheet l INVENVTOR.

Clarerrce fZ Brae/7.

ATTORNEYS.

C. A. BROCK VACUUM CLEANER May 16, 1939.

Filed Dec. 18, 1935 5 Sheets-Sheet 2 M g a m n m h K ATTURNEYS.

May 16, 1939. c A, BRQCK 2,158,717

VACUUM CLEANER Filed Dec. 18, 1935 3 Sheets-Sheet 3 mammal/11,":

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o o 0 0.0 0 v 674222220? 1? Brock Patented May 16, 1939 UNITED STATES PATENT OFFICE VACUUM CLEANER Clarence A. Brock, Detroit, Mich., assignor, by

mesne assignments, to Rexair, Inc.. a corporation of Delaware 8 Claims.

This invention relates generally to separators. More particularly it relates to a separator designed ior removing dust or other solid particles from air, and contemplates the provision of a structure particularly adapted for use in a vacuum cleaner system.

While it will be clear that the specific embodiment of the invention herein shown and described is illustrated as a part of a vacuum cleaning 10 system, the generic inventive concept disclosed will find practical utility in many other fields, such for example as air pumps, air purifiers and dust separators generally.

It is a general object of the present invention to provide a dust separator primarily adapted for use in a vacuum cleaning system, in which 9. flexible tube or conduit is used to connect the dust separator to the nozzle. In order to obtain a better and more complete understanding of the objects and advantages of the present invention,

reference may be had to applicants prior copending application, Serial No. 723.840, filed May 4, 1934, in which is disclosed a dust separator for vacuum cleaner systems having many features in common with the present invention.

One of the important features of the present invention consists in the provision of novel means i or mounting the motor and fan elements in order to virtually eliminate the vibration and noise norao mally resulting from their operation. The present invention contemplates the provision of an annular resilient member which not only constitutes the sole mounting for the blower housing, but also constitutes a partitioning member which serves,

35 to divide the outer casing structure into the separate upper and lower compartments in which the blower serves to create a substantial difference in pressure. The pressure difierential thus created tensions the resilient member forming 40 the partition and serves to support the blower and housing entirely out of contact with the easing in which it is mounted. With particular reference to this feature, it will be appreciated that the motor mounting disclosed herein, although 45 illustrated in connection with a vacuum cleaner system, will find great utility in many other installations.

Another object of the present invention resides in a novel means for collecting the accumulated to dust and other foreign matter and in the provision of a removabiy mounted dust bin slidably disposed in the dust separator housing. The invention contemplates the provision of a bin associated with the separator unit which, when desired,

56 may be bodily removed and emptied. Sealing means are provided which cooperate with the marginal edges of the bin in order to effect an air-tight closure of the bin with respect to the housing in which it is disposed.

Another feature of the present invention rc- 5 sides in the provision of a dust separator element of particularly not cl and efiicicnt although simple construction, which is so formed that it inl1erently prevents the accumulation of dust inter-lolly thereof during the operation of the apparatus. 10

Still further, the invention contemplates the utilization of a filter element through which the air is passed after being subjected to the action of the mechanical dust separator. This filter element is removably mounted within a compartmerit of the casing and serves to collect and retain whatever dust is not eiicetlvely separated from the air by the mechanical means provided.

The present invention further contemplates the provision of an opening between the portion of 20 the casing in which the removably mounted dust bin is located and the compartment in which the filter element is disposed in order that access may be had to the filter compartment through the dust bin compartment. 25

Another object of the present invention consists in the novel arrangement of louvers which permit air which is passed through the filter to escape to the outside of the casing, and further, the provision of means for closing and sealing said louvers when desirable.

Further, the invention contemplates a compact, attractive and convenient arrangement of parts such that the dust separator unit as a whole may be easily transported from place to place and may be slid across the floor as it is used without likelihood of upsetting.

Many other and further objects and advantages of the present invention will be apparent from the following specification when considered in connection with the accompanying drawings forming a part thereof.

In the drawings:

Figure 1 is a side elevation of the completely assembled dust separator showing a conventional nozzle secured thereto by means of a flexible tube;

Fig. 2 is an enlarged vertical sectional view, illustrating the interior construction and arrangement of parts;

Fig. 3 is a transverse sectional view taken on the line 3-3 of Fig. 2, showing in plan the partition member dividing the easing into upper and lower chambers;

Fig. 4 is a fragmentary transverse sectional view, taken on the line l4 of Fig. 2, showing the dust bin compartment and the manner in which the dust bin is anchored within the casing;

Fig. 5 is a fragmentary transverse sectional view, taken on the line 5-5 of Fig. 2 showing the manner in which the partitioning member for separating the dust bin compartment from the filter compartment is retained in position;

Fig. 6 is a fragmentary enlarged sectional view, taken on the line 66 of Fig. 3, showing the resilient means for mounting the blower housing with respect to the casing;

Fig. '7 is a transverse fragmentary sectional view, taken on they line 1-1 of Fig. 2, illustrating the manner in which the filter is mounted within the filter compartment;

Fig. 8 is a transverse sectional view similar to Fig, 7, showing means provided for closing the louvers of the filter compartment when it is desired to use the dust separator as a blower;

Fig. 9 is a fragmentary sectional view illustrating a modified means for mounting the blower housing within the casing;

Fig. 10 is a fragmentary sectional view illustrating a further modified form of the invention showing a still different means for mounting the blower housing within the casing; and

Fig. 11 is a fragmentary enlarged sectional view, taken on the line IIH of Fig. 2, showing the structure of the dust separator element.

With more particular reference to the drawings, the specific embodiment of the invention shown therein comprises in general a casing Ill which may be formed of composite sheet metal or other suitable construction and which is illustrated as a casting. The casing is eferably generally oval in shape and is provided in its central portion with a vertically extending partition wall II. The casing as a whole is open at the top and is adapted to receive a suitable cover I2. This cover I2 is provided with a flange l3 at its marginal edge adapted to mate with a corresponding flange H on the upper marginal edge of the casing l0.

On one side of the partition wall II in the easing III is mounted a blower housing i6 which has mounted therein a suitable electric motor l1 serving to drive a plurality of centrifugal fans H which provide a multiple stage blower construction tending to draw air axially downward through the blower housing IS. The blower housing is provided at its upper end with an annular flange l9 which has a groove in the axial face thereof. A cover plate 20 has a grooved face adapted to mate with the grooved flange I9 and is secured thereto by means of a suitable annular series of screws 2|. A pair of partitioning members 23 and 24 have registering circular apertures therein slightly larger than the diameter of the flange l9 and associated cover plate 20, and have complemental circular grooves in their adjacent faces. An annular packing strip 25, having beaded edges, and preferably formed of rubber or suitable resilient composition, has one beaded edge clamped between the cover plate 20 and flange is by means of the screws 2| and has its other beaded edge clamped between the partitioning members 23 and 24 and securely locked in place by means of bolts 26. It will be appreciated that the bolts 26 not only serve to lock the partitioning members 23 and 24 in predetermined position but also serve to interlock the flange It on the casing ill to the flange l3 on the cover l2, thus securing the cover to the casing structure. Inasmuch as the partitioning members 23 and 24 have their marginal edges, throughout some considerable extent, exposed exterlorly of the casing, throughout this exposed area they may be provided with suitable finish moldings 28 to provide an attractive exterior appearance.

The cover plate 20 has mounted substantially centrally thereof an annular series of ball bearings 30 in which is Journaled a blower shaft II. This blower shaft 2| is preferably directly connected to the electric motor I1 and serves to drive the vertical series of centrifugal fans II which tend to draw air downwardly through the blower housing. Surrounding the bearing structure II in the cover member 20 is an annular series of inlet apertures 32 which serve to permit the flow of air from the upper portion of the casing enclosed by the cover plate, downwardly into the multistage blower l8. Secured to the upper end of the shaft 3| of the blower, above the cover plate 20, is a mechanical dust separator element 35 adapted to be driven by the shaft.

While applicants prior co-pending application, referred to above, discloses a dust separating element adapted to operate on the same general principle as that disclosed herein, the element 35 is quite different m construction and considerably more efficient in operation. While in the above co-pending application, auxiliary means are shown and required to prevent accumulation of dust interiorly of the dust separator element. the present invention contemplates the provision of a dust separator element which is so constructed and designed that such auxiliary means may be entirely dispensed with.

While the element 35 may be formed in any convenient manner, it has been found preferable to construct it from a single, integral sheet metal stamping to provide a frusto-conical structure having helically extending slots throughout substantially its entire peripheral surface. It is considered extremely important that no substantial surface area exist internally of the dust separator element because it has been found that a certain limited amount of dust which passes through the slots in the surface of the element tends to build up on the interior thereof and hence necessitates relatively frequent removal of the dust separator element and cleaning of the interior thereof. The slots in the peripheral surface of this dust separator element are defined by helically disposed bars which, it may be seen by reference to Fig. 11, have their exterior surfaces rounded and the forward or leading edges 44 thereof extending radially inwardly a slightly greater distance than the trailing edges 43. It will be apparent from this construction that, as the dust separator element rotates in the direction indicated by the arrow, the air entering the slots therein is required to follow a relatively tortuous path and due to the inertia of the dust particles, it will be seen that they will necessarily impinge upon the rounded surface of the bars and be centrifugally driven away from the element, thus preventing their entry into the interior thereof.

The specific shape of the separator element 35 has been found to be a very important factor in preventing the accumulation of dust interiorly thereof. It has been found that by accurately regulating the shape proportions of the separator elements building up of dust on the inside surface is effectively prevented. It has been found particularly satisfactory to form the dust separator element of a relatively short axial length so that its axial length is approximately one-third of the diameter of its large end and about one-half the diameter of its smaller end.

The actual physical size 01' the element as a iii] whole is relatively unimportant as long as the proper proportions are maintained. It has been further found particularly desirable that the separator be formed with a flat top which lies in a plane transverse to the axis of rotation of the element as a whole.

The dust separator element is provided at its lower axial end with a radially extending fiange 38 which is mounted on a suitable spider 33 secured to the shaft 3| of the motor ll. It will be seen that as the motor I1 is run, air will be drawn inwardly through the slots in the separator element 35 by means of the centrifugal blowers l8 and dust in such air will impinge upon the rounded surfaces or the bars serving to define these slots and be centrifugally driven away. In order to insure that no dust-laden air will enter the necessary clearance between the dust separator element and the cover plate 20, a series of radially disposed vanes 31 are formed on the lower side oi the spider 33. These vanes or blades act as a centrifugal fan and maintain a constant but relatively small outflow of air through this space, thus insuring that no dust-laden air will enter the interior of the dust separator element at this point. It will therefore be seen that all air which enters the interior of the blower housing will have been processed to remove the dust therefrom and that a much smaller, but equally constant outflow of air will be created by the vanes 31 operating'in the clearance between the dust separator element and the cover plate 20, thus insuring that all air passing through the annular series of inlet ports 32 to the blowers will be substantially dust-free.

The casing II) has an inlet opening 40 which may be formed integrally therewith and may be internally threaded to facilitate the connection of a flexible conduit 4! thereto which is adapted to be connected to any suitable nozzle, such for example as 42. An inlet duct 45 is connected to the inlet opening 40 and serves to provide communication between the inlet opening 40 and the space within the casing adjacent the dust separator element 35 above the partitioning members 23 and 24. This conduit 45 preferably extends arcuately around the electric motor I! in the base of the casing and thence upwardly through suitable registering apertures in the partitioning members 23 and 24.

In the lower side of the casing on the opposite side of the partition wall from the portion in which the motor and blower are mounted, is a filter compartment generally designated as 50. Suitable louvers 5| are provided in the wall of the casing to permit the escape of air from the filter compartment 50. An outlet aperture is formed in the partition wall II to provide communication between the compartment housing, the motor and blower, and the filter compartment and this aperture has preferably permanently mounted therein a nipple which is adapted to receive a dust filter bag 55 of a shape conforming substantially to the shape of filter compartment 50. This filter bag 56 is preferably secured on the nipple 55 by means of a garter spring 51 or other suitable securing means. The filter compartment is closed at its upper side by means of a removable partition member 50 seated on a suitable gasket Bi and having one of its edges secured in a recess 62 formed in the casing iii. The opposite edge of this partition member is retained in position by means of a spring element 63 secured to the partition wall H by means of a pair of bolts 64. This spring element 53 has a further important function which will hereinafter be clearly seen.

From the foregoing, it will be clear that dustladen air taken in by the nozzle 42 will be conducted through the fiexible tube 4| into the inlet 40. From the inlet 40 it will be conducted upwardly through the partition walls 23 and 24 into the upper portion of the casing in which is located the rotary dust separator element 35. It will be clear that the suction pressure generated by the multi-stage fan I8 driven by the electric motor I1 will draw this dust-laden air toward the separator element 35 and that the separator element will function to remove from the air by centrifugal force, the dust particles, and will draw only substantially pure processed air downwardly through the blower housing. It will be seen that the only outlet for the air drawn into the blower housing is through the nipple 55 in the partition wall ii and hence into the filter bag 55 secured thereto.' The filter bag will, therefore, serve to collect any dust which was not extracted from the air by means of the centrifugal dust separator element 35 and consequently only substmtialiy pure air will be passed from the filter compartment 53 out through the louvers 5i.

It will likewise be seen that due to the action of the blowers I8, a substantial pressure differential will be created between the compartment above the partitioning members 23 and 24 and the compartment in which the blower housing is mounted. Due to this substantial pressure differential the greater pressure in the lower compartment in which the blower housing is mounted, will tend to move the blower housing, blower and motor connected thereto, upwardly toward the area of decreased pressure. This upward movement of the blower housing and motor will be resisted by the resilient packing ring element 25 which isclamped between the partitioning elements 23 and 24 at its outer periphery and between the blower housing l6 and cover plate 20 in its inner periphery. This pressure differential has been found to be sufllclently great so that the entire blower housing, dust separator, blower and motor associated therewith, will be raised slightly when the blower is operated, thus tensloning the resilient packing element 25 and supporting the blower housing entirely free from the casing structure except for the interconnection of the resilient packing member 25. It will be appreciated that this construction serves materially to prevent the sound and vibration resulting from the relatively high speed operation of the blower and dust separator elements from being transmitted to the casing and consequently virtually eliminates the noise usually attendant upon the operation of machines of this general type. A resilient padding element 66 may be secured to the lower axial end of the motor in order to cushion this portion of the apparatus with respect to the casing l0. It will be appreciated, however, that as the blower is operated, the motor, blower housing, and dust separator, which together provide a substantially unit construction, will, due to the action of the blower, be raised from the floor of the casing Ill and will be maintained entirely out of contact therewith during the time the machine is operated. The function of the resilient cushioning member 65 is merely to provide a resilient seat for the blower housing during times when the machine is not in operation. Consequently, it will be seen that this resilient cushioning member serves to relieve the annular resilient member 25 from unnecessary strain in supporting the blower housing when the machine is not operating. It is to be particularly noted that the rubber ring 25 is placed under tension as the blower unit rises in operation. This is important from the standpoint of reducing the transmittal of audible vibrations from the blower unit to the main casing as it has been found that were such rubber placed under compression, instead of tension, the reduction of noise would be rather insignificant as compared to the present case where the rubber is placed under tension.

A suitable circular aperture 10 is provided in the upper surface of the cover I2 and has surrounding it a packing member II upon which is seated a removably mounted glass cover panel 12 retained in position by means of a suitable frame 13. It will be clear that this cover panel 12 is sufllciently large in order that access may be had to the rotatable dust separator element 35 and that this element may be cleaned, adjusted, dismounted or replaced at will without disturbing the mounting of the cover I2 on the casing I0.

As may be desired, a handle Il may be sultably,secured to the top of the cover member I2 in order to provide convenient means for transporting the dust separating apparatus from place to place. The opposite end of the cover section I2 to that in which the rotary dust separator element is mounted is partitioned off by means of an integrally formed partition wall 16 which mates with the partition member 23 to provide a closed compartment at the upper end of the dust separator cover. In this compartment is mounted a suitable terminal block 11 to which is connected a cord 18 adapted to connect the dust separator with a suitable source of electric current. Also mounted within this compartment is a suitable switch I9 which serves to provide means by which the electric motor may be started and stopped. Connection wires 80 extend from the switch "I9 and connector block Tl down to the electric motor H.

In the space between this portion of the cover section I2, just described, and the upper surface of the filter compartment 50, is located a removable slidably mounted dust bin 85. This dust bin 05 preferably has an exterior face provided with a suitable handle 05 and mates closely with the adjacent walls of the casing I and cover I2. The upper marginal edge of the dust bin is preferably beaded and provided with a finish molding 08 which, when the dust bin is slid into position, will mate with the finish molding 20 on the lower partition member 24 to provide a substantial continuation thereof which it will be seen extends entirely around the dust separator casing. The drawer or dust bin 85 preferably extends substantially the full width of the casing l0 and the under side of the partition member 23 is preferably provided with a resilient sealing strip 80 seated therein throughout the extent which this partition element mates with the drawer in order to provide an eifective and tight seal of the partition member 23 with respect to the top marginal edge of the bin 05. The rear wall of the bin on its exterior side substantially in the central portion thereof is provided with a spearhead 9I preferably formed integrally with the drawer and adapted to enter between the spaced prongs 92 of the spring element 53. These prongs 92 are preferably formed by bending suitable lateral projections on the spring element 08 between the points at which this spring element is secured to the partition wall II. It will thus be appreciated that the dust bin is maintained in predetermined position with respect to the casing in which it is mounted and that it is locked in position by means of the spring element 92 and the mating spearhead 9|. It will further be seen that the top marginal edge of this drawer is effectively sealed by means of the resilient sealing element 90.

A suitable aperture 95 interconnects the portion of the casing in which the bin 05 is mounted with the portion of the casing surrounding the rotary separator element 35. Due to the centrifugal action of the rotaryseparator element 35 the dust particles in the air entering the portion of the casing in which this element is located will be driven to that portion farthest away from the rotary separator element 35 and will consequently drop directly into the dust bin 85. From the foregoing, it will be appreciated that as the nozzle 42 serves to draw dust from articles being cleaned, this dust will be conveyed through the inlet 40 and intake conduit 45 into the chamber surrounding the rotary dust separator element. At this point the dust particles will, by means of the rotary dust separator, be separated from the air and will drop into the bin 85. The clean air passes downwardly through the multiple stage blower and out through the filter bag 56 which serves to subject the air to further cleaning action. From the construction described above, it will be apparent that the dust bin 85 may be conveniently removed whenever it is desired by bodily separating it from the casing I0. Accumulated dust, therefore, may be emptied from the bin 05 at convenient intervals without in any way disassembling the machine.

At certain times it is found desirable to use a machine of this general type for providing a blast of air for various cleaning operations and other purposes. In order to conveniently effect this result, the filter compartment is provided with an aperture IIIII internally threaded in substantially the same size and manner as the inlet aperture 40. In normal operation of the machine, this aperture I00 may be left open as may be desired and some of the exhausted air from the dust separator will be discharged therethrough. However, the majority of the exhausted air will pass outwardly through the louvers 5 I. While any suitable means may be used to close the louvers 5i when it is desired to use the apparatus as a blower, it is preferable to provide a convenient means for positively and effectively sealing these louvers during such time. One way in which this may be effectively accomplished is by means of a sheet metal element I0l bent to a configuration substantially the same as the exterior of the casing and provided throughout a substantial area in its end portion with a sealing strip of soft rubber or other resilient material I02, which when the strip IN is mounted in position, serves to cover and seal the louvers 5|. This element IIII may be retained in place by means of a fitting or collar I03 which is screwed into the threaded aperture I00. Thus, it will be seen that convenient means are provided for sealing the louvers 5| when it isdesired to use the dust separator as a blower. It will be apparent that when the member ID! is seated in place with the resilient sealing members I02 Gil covering the louvers Ii all air exhausted from the fllter compartment will be forced out through the aperture I03 and may be directed as desired by any suitable apparatus conventional in the art.

In Figs. 9 and 10 are illustrated modified forms of the sealing elements adapted for mounting the blower housing within the casing. In the form of the invention shown in Fig. 9, an even more resilient mounting for the blower housing has been provided than was illustrated in the preferred form of the invention described above. In this form of the invention, a partition element llil of substantial vertical extent is substituted for the partition element 13. This partition element I iil is provided in its lower face with a groove II I mating with the complements] groove I I2 formed in the lower partition element 24. These two elements serve to grip the beaded marginal edge of a relatively wide frusto-conical sealing strip 2. The inner marginal edge of this sealing strip I I2 is also provided with a suitable bead which is gripped between the blower housing l6 and its cover 24 substantially as was described in connection with the preferred embodiment of the invention. It will be appreciated that in this form of mounting, the annular sealing strip 1 l2 may be substantially tensioned in order to provide accurate centering of the blower housing with respect to the casing in which it is mounted and the operation of the blower increasing the pressure on the lower side of this sealing element H2 will serve to additionally tension this element and provide a stable, yet extremely resilient, mounting ior the moving parts of the dust separator.

From the foregoing it will be appreciated that in the construction described, the free and resilient mounting of the blower housing is due entirely to the fact that this housing is elevated by means of the substantially increased pressure below the resilient sealing elements 25 and H2. It has been seen that this pressure diflerential serves to raise the housing bodily from the floor of the casing i0 and maintains the housing freely mounted on an air cushion within the casing and the sealing element under substantial tension. It will be appreciated that this result will only obtain when the housing is disposed in substantially the position shown in the drawings and that the blower housing would not necessarily be maintained tree from the walls of the casing I if the casing II] were not disposed in vertical position. In Fig. 10 I have illustrated a modified form 01 the invention in which eilective resilient means are provided for mounting the blower housing resiliently with respect to the casing in which it is mounted, which means are effective to maintain this resilient mounting irrespective of the position in which the casing may happen to be disposed. In this form of the invention, the oasing l0 and cover i2, therefore, have disposed between their mating flanges partitioning members 5 and 6 which together provide an annular recess adapted to receive an annular sheet metal cup-shaped member Ill which serves to seat a resilient packing member "8. This packing member H8 may be formed of sponge rubber or any other suitable highly resilient material and is adapted to be maintained between the sheet metal cup-shaped member Ill and the adjacent walls of the blower housing by being vulcanized or otherwise suitably adhered to both thereof. It will be appreciated that this resilient sealing member H8 is secured to the adjacent walls of the blower housing throughout a substantially large area and provides eil'ective sealing and resilient mounting 0! this housing irrespective of the position in which the casing is inclined. Furthermore, operation of the blower unit will place the member iii under tension tor the same reasons as set forth in the first two mentioned constructions.

Many other and further modifications oi the invention falling within the scope of the subjoined claims will be apparent to those skilled in the art.

What is claimed is:

1. In a dust separator, a casing, a housing within said casing, a resilient partitioning member clamped to said casing and said housing serving to divide said casing internally into separate upper and lower compartments, and means within said housing for drawing air from said upper compartment into said lower compartment whereby said housing will be bodily raised and said partitioning element will be tensioned.

2. In a dust separator, a casing, a housing within said casing, a blower within said housing, a resilient partitioning member clamped to said blower housing and easing, serving to divide said casing internally into separate upper and lower compartments and providing when said blower is operating the sole means interconnecting said blower housing and easing.

3. In a dust separator, a casing, a blower housing within said casing, a blower within said hous ing, an elastic annulus clamped to said housing and said casirm, serving to divide said casing internally into separate upper and lower compartments, the marginal ends of said annulus being preformed to effect a tight sealing engagement with said housing and casing, and means for operating said blower to move air from the upper compartment into the lower compartment whereby said housing will be supported on an air cushion when said blower is operating.

4. In a dust separator, a casing, partition members extending transversely oi said casing, said partition members having registering apertures, an elastic annulus having its outer marginal edge clamped between said partition within said registering apertures members and extending inwardly of said registering apertures, serving to divide said casing internally into separate upper and lower compartments, and a blower housing formed of separable parts disposed within said registering apertures and clamping the inner marginal edge or said annulus between the separable parts thereof, whereby said housing will be supported on an air cushion when said blower is operating.

5. In a dust separator, a casing, a blower housing within said casing, means for drawing air through said blower housing and resilient sealing means secured to said casing and housing for interconnecting the same whereby the air circulated through said housing serves to support the same and to place said sealing means under tension.

6. In a dust separator, a casing, a blower housing disposed within said casing, an elastic annulus interconnecting said blower housing and casing and serving to divide said easing into separate upper and lower compartments, a blower within said housing serving to draw air from said upper compartment into said lower compartment whereby to eflect limited upward movement of said housing with respect to said casing.

I. In a dust separator, a casing, a blower housing disposed within said casing, an elastic annulus nulus having its outer edge clamped in sealing engagement with said casing. a blower housing within said casing, a cover for said blower housing secured thereto, the inner marginal edge of said annulus being clamped between said blower housing and cover whereby to divide said easing into separate upper and lower compartments, and a blower in said housing serving to draw air from said upper compartment into said lower compartment whereby to eflect limited vertical move- 1 ment of said housing with respect to said casing.

CLARENCE A. BRDCK.

CERTIFICATE OF CORRECTION.

Patent No. 2,158,717

GLAREiCE A. BROCK.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 5, second column, line 35, claim 3, for the word "ends" read edges; line 1 ,7, claim i strike out the word "members" and insert the same after "partition" in line 1 ,6, same claim; and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 20th day of June, A. D. 1959.

(Seal) Henry Van Arsdale Acting Commissioner of Patents.

nulus having its outer edge clamped in sealing engagement with said casing. a blower housing within said casing, a cover for said blower housing secured thereto, the inner marginal edge of said annulus being clamped between said blower housing and cover whereby to divide said easing into separate upper and lower compartments, and a blower in said housing serving to draw air from said upper compartment into said lower compartment whereby to eflect limited vertical move- 1 ment of said housing with respect to said casing.

CLARENCE A. BRDCK.

CERTIFICATE OF CORRECTION.

Patent No. 2,158,717

GLAREiCE A. BROCK.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 5, second column, line 35, claim 3, for the word "ends" read edges; line 1 ,7, claim i strike out the word "members" and insert the same after "partition" in line 1 ,6, same claim; and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 20th day of June, A. D. 1959.

(Seal) Henry Van Arsdale Acting Commissioner of Patents.

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