US2599842A - Apparatus for cleaning filter screens - Google Patents

Description

' June 10, 1952 J. KlNG, JR 2,599,842

APPARATUS FOR CLEANING FILTER SCREENS Filed April 18, 1951 3 Sheets-Sheet l N 9 h B INVENTOR 31W J mu 3 MJWWPMAW ATTORNEY June 10, 1952 Jf K N JR 2,599,842

APPARATUS FOR CLEANING FILTER SCREENS Filed April 18, 1951 3 Sheets-Sheet 2 & mg wk w INVENTOR ATTORNE Y3 5 Sheets-Sheet 5 J. F. KING, JR

APPARATUS FOR CLEANING FILTER SCREENS t? INVENTOR BY j June 10, 1952 Filed April 18, 1951 Patented June 10, 1952 APPARATUS FOR CLEANING FILTER SCREENS.

James F. King, Jr.. Winston-Salem, N. 0., assignor to The Bahnson Company, Winston- Salem, N. 0., a corporation of North Carolina Application April 18, 1951, Serial No. 221,601

6 Claims. (01. 183-52) The present invention relates to apparatus for cleaning; air filters and more particularly to an improved device for stripping air borne material from filter screens of the flat, reticulated type through which the air is passed for recirculation in an air conditioning system.

In textile factories particularly, a considerable mass of lint usually becomes entrained with the recirculating air and is caught by a filter screen as the air passes through it. This lint must be removed periodically if a condition of low static pressure is to be maintained through the air opening across which the filter screen is placed. One system of cleaning, as described in a copending' application of Agnew H. Bahnson Jr., Serial 184,316 filed September 11, 1950, now Patent No. 2,596,518, granted May 13, 1952, provides. for periodic operation of a scraper blade over the face of the screen from top to bottom and. back again. During the downward stroke, the edge of the blade is pressed into contact with the screen surface so as to dislodge the lint and other foreign matter. When the blade reaches the bottom of the screen, its motion is reversed by reversing the drive for the blade and the latter returns to the top of the screen where its motion is again reversed thus'starting the blade downwardly again. The scraper blade is mounted on pivots and, by means of trip mechanisms at the top and bottom of the screen, the edge of the blade is thrown into pressure contact with the screen surface at the starting point of the downward cleaning stroke and out of contact with the screen surface at the end of such stroke. Thus during the downward stroke the blade edge engages the screen but during the return, upward stroke to the starting position, the blade edge is held away from the screen.

This application concerns the drive for the scrape blade assembly and provides an improved arrangement for rocking the scraper blade about its pivotal support into and out of engagement with the surface of the screen as the blade reaches the top andbottom respectively of the screen.

The principal advantage of the improved construction about to be described is that the electric motor furnishing power for driving the blade does not have to be reversed in order to reverse the direction of travel of the blade when the latter reaches the top or bottom of the screen. This simplifies the control in that it eliminates the necessity for installing motor controlling limit switches which are usually necessary for effecting reversal of electric motor drives. More- 2 over, the improved construction provides a more positive control over the throw of the scraper blade into and out of engagement with the surface of the screen.

More specifically, the present invention provides an improved, direction reversing mechanism for the scraper blade of a filter screen cleaning unit comprising a motor driven belt running in one direction only around discs 10- cated at the top and bottom of the screen at one side thereof, and a crank arm, one end of the-arm being pivotally connected to a point of attachment on the belt and the other endbeing secured fast upon a rock shaft which serves as a pivotal support for the blade assembly, the shaft being journalled in vertical guides at the sides of the screen. Because of the connection between the belt and crank arm, the latter will be compelled to travel with the connecting point on the belt thus effecting a reciprocating movement of the rock shaft and blade assembly in the vertical guides, the direction of which is reversedeach time the direction of travel of the point of connection between the belt and crank. arm is reversed as such point travels around one of the discs. The crank arm, and hence the rock shaft and blade assembly, in following the connection point to the belt around the disc move through an angle determined by the diameter of thedisc thus effecting a throw of the blade assembly into surface contact with the screen as the crank arm moves around the upper disc and out of. surface contact each time the arm passes around the lower disc.

A preferred embodiment of the invention is illustrated in the accompanying drawings as. to which Fig. 1 is a view in perspective of the filter screen and improved cleaner mechanism; Fig. 2 is a view in vertical longitudinal section; Fig. 3 is a horizontal longitudinal section taken on line 3-3 of Fig. 2; Fig. 4 is a fragmentary vertical transverse section on line -A of Fig. 2 but drawn to a-larger scale; Fig. 5 is a vertical transverse section on' line 5--5 of- Fig. 6; and Fig. 6 is a fragmentary vertical longitudinal section based upon Fig. 2'but drawn to a larger. scale for the purpose of better illustrating constructional detail.

With reference now to the drawings, and Figs. 1 and 2 in particular, the filter unit is comprised of a rigid, upright rectangular frame 50 made of metal. The bottom element of the frame is constituted by an elongated box 5| which serves as a receptacle for lint and other'forei gn matter removed from the filter screen; the sidesof the frame are formed by plates 52, 53 each having a longitudinally extending channel 52a, 53a; and the top member of the frame is constituted by a flat plate 55.

The top wall |a of the box is slotted along the plane of the screen to receive the falling lint removed by the blade, and a hinged, clean-out door section 5|b extending for the full length of the box is provided in the front wall to facilitate removal of lint when the box is in need of emptying.

The reticulated, fiat filter screen 56 is stretched taut in the frame and is secured to the latter along the top and bottom. The entire filter unit is set into filtering position which may for example be in a wall opening between two rooms. Since the present invention is directed to the filter unit per se, it has not been considered necessary to illustrate any part of the air conditioning system with which it is associated. However it will be understood that the air to be conditioned is blown or drawn through the filter screen 56 under pressure for cleaning. The air conditioning system may also include cooling or heating, moistening or drying components for the air but these are immaterial to the invention.

The longitudinally extending channels 52a, 53a of the side members of the frame have a rectangular configuration and serve as guides for blocks or slides 51, 58 which constitute the end supports for the blade assembly. Slides 5?, 58 are provided with horizontal bores 51a, 58a respectively which serve as bearings for rock shafts 59, 66. A single leaf, torsion spring 6| is secured to and extends axially from the inner end of rock shaft 59 and a similar spring 62 extends axially from the inner end of rock shaft 69. Secured to the opposite ends of springs 6|, 62 are axially extending shafts 63, 64, respectively which are received in longitudinal bores of blocks 65, 66, respectively, being locked therein by set screws ,61. Blocks 65, 66 are secured, as by welding, to the under side of a plate 68 generally coextensive in width with screen 56 and which projects down and inward in the direction of the screen. Extending across the bottom of this plate and secured thereto is a stripper blade 69 preferably of relatively stiff rubber. During the downward stroke, the edge of the blade is adapted to bear against the screen at an angle of about 30 from the vertical. The included angle between the screen and blade edge is however not too critical and hence the 30 angle illustrated may be departed from considerably.

To prevent undue yielding of the screen from the pressure exerted by the stripper blade 69, a backing plate 1| extends across and contacts the face of screen 56 opposite to that contacted by blade 69. Plate 1| is generally on the same level with blade 69 and is secured at each end to the slidable blocks 51, 58.

While most of the lint will be pushed downward by the downward advance of blade 69 and drop into the box 5|, some of the lint as it becomes balled or rolled up by the advancing motion of the blade may nevertheless be caught under the blade edge and left behind. To assure removal of this remainder, there is provided a second, blade-like member 12 secured to plate 68 above blade '69 extending horizontally in the direction of but terminating just short of the screen surface. The scraper blade 69 and the trailing blade 12 together with that portion of plate 68 included therebetween, see Fig. 5, constitute a trap chamber '13 open in the direction of screen 56. Due to the suction of air through the screen, a partial vacuum is created in chamber 13 throughout its length and such vacuum has been found most effective in trapping and bringing down any lint rolls which happen to be forced under the edge of blade 69. The lint so trapped is discharged into box 5| when the blade assembly reaches the end of its downward stroke and is thrown to its out-of-contact position in a manner to be described hereinafter. As previously explained, the details of the vacuum trap chamber are claimed in the other, copending application of Agnew H. Bahnson, Jr., Serial No. 184,316.

For advancing the blade assembly downwardly across the face of the filter screen, a flexible, endless belt type of drive, preferably of the positive chain and sprocket type, is utilized at each end of the blade assembly. Thus as most clearly seen in Fig. 2, a geared down electric motor 14 supported upon bracket 15 attached to the left side of the screen frame 50 drives sprockets 16, 11 at the upper left side of the frame. Sprocket TI is connected by chain 18 to another sprocket 19 located at the lower, left side of the frame and which is mounted upon a shaft journalled in sleeve bearing block 800.. Sprocket I6 is connected by another chain 8| to another sprocket 82 located above it and which is secured fast upon a shaft 83 extending transversely of frame 59 and journalled at its ends in sleeve bearing blocks 84, 85. A sprocket 86 secured fast on the opposite end of shaft 83 is connected by chain 81 to a sprocket 88 secured fast upon a stub shaft 89 journalled in sleeve bearing block 90 at the same level as the shaft of motor 14. Another sprocket 9| fast upon shaft 99 is connected via chain 92 with another sprocket 93 mounted upon shaft 94 rotatable in sleeve bearing 94a located at the lower right corner of the screen frame at the same level as sprocket 19. Thus when motor I4 is energized, it will drive chain 18 at the left side of the frame directly. The correspondingly positioned chain 92 at the right side of the frame will be driven indirectly through the auxiliary sprocket and chain connections described, and in the same direction as chain 18.

As more clearly seen in Figs. 3 and 4, the respective axes of rotation of the four sprockets l1, 19, 9| and 93 are located in a common vertical plane coincident with the aligned axes of the two rock shafts 59 and 69. Hence each of the chain belts I8 and 92 will occupy a vertical plane extending transversely of the aligned axes of the two rock shafts 59, 60. A crank arm 95 is secured fast upon rock shaft 59 at one end, and the other end of the arm is pivotally connected at 96 to one link on chain 18. In a similar manner, another crank arm 91 has one end secured fast upon rock shaft 69 and the other end pivotally connected at 98 to a link on chain 92, it being noted that the pivotal connections 96, 98 lie on the same flight of the chains and at like levels. Movement of chains 18 and 92 in the direction indicated on Fig. 4 cause the blade assembly to be carried downwardly with the blade 69 pressed against the surface of screen 56, the downward pull being exerted from the chains through pivotal connections 96, 98 and from the latter via crank arms 95, 91, rock shafts 59, 69, and torsion springs 6|, 62 to the blade assembly consisting of plate 68 and the two blades 69, 72.

When the pivotal connections 96, 98 reach the bottom, pass around the lower sprockets Hi, 93 andstart upward, it will be" evident" that crank arms 95'; 91 will be thrown from thlefti'to: the right side of the planethrough the centers of the-"four sprockets 1T,"-19-, 9| and '93 viewed from the left in Fig; '2, i; e.'=as in Fi '4, thus throwing"rock shafts'59, 60 counterclockwise-to the other position shownin' broken lines in 4 wherein the stripper blade is out of contact with the screen surface and reversing the directionof motionof the blade assembly; 'Whe'n the pivotal connections 95, fli'reachthe top and passaround the upper sprockets"'l'1and 9|, crank-arms'95, 91 are thrown back to the left side of the plane throughthe sprocket centers to the position shown in fulllines in Fig. 4 thus again reversing the direction of "travel of the bladeassembly and ain throwing the blade 69 into contact. with the surface of the filter screen'for the downward clean -off stroke. The angular relationship between crank arms'Q-S, 91 and-blade is such that the edge of blade 69 will contact the screen when the crank arms 95, 91 have moved through approximately two thirds of their angle of throw as" the pivotal connections 95-, 98 travel from one side to the other of the upper sprockets I1 and SI. The remaining one thirdof the angular throw of crank arms 95; 91 is used to load the torsion springs El, 62 thus assuring a firmpressure of the edge of blade 69 against screen 55 during the downward stroke. The load of springs SI, 62 against the blade 69 is absorbed by the backing plate H which as previously explained travels with the cleaning blade.

Cleaning of the filter screen can be made selective at the will of the user in which suitable control switches would be included in the circuit of motor 14 to connect the latter to a source of power whenever the screen was deemed in need for cleaning. Or, operation of the cleaner could be made automatic in which case suitable timer mechanism would be incorporated in the control circuit of the motor to effect energization thereof at selected intervals fora selected period of operation in each interval.

In conclusion it will be understood that the particular embodiment of my invention hereinabove described is but typical of the many structural arrangements possible and hence various modifications thereof may be effected without however departing from the spirit and scope of the appended claims.

Accordingly, what I claim as new and desire to secure by Letters Patent of the United States 15:

1. Apparatus for stripping lint and like material from a flat filter screen through which air is adapted to be passed comprising a frame having said filter screen secured thereto, said frame including a pair of side members provided with longitudinally extending guides, a slide disposed in each guide, a wiper blade for the screen extending transversely of said frame, means supporting said blade on said slides for rocking movement about an axis extending longitudinally ofthe blade to bring the blade edge into or out of contact with the surface of said screen, a flexible drive at one side of said frame for said blade, said drive including a belt occupying a vertical plane extending transversely of the support axis for said blade and running on rotatable discs disposed respectively at opposite ends of said frame, a crank arm having one end thereof pivotally attached to a connection point on said belt, means for driving said belt and means interconnecting the other end of'said crank arm"with said blade supporting means such that the throw of the cran'k-- arm effected each time the pivoted "end 'of' the latterpasse's around one of said discs isconverted into a rocking movement'of said blade. T

2, Apparatus for stripping lint and like material from a fiat'filter'screen through which'air isadapted to be passed comprising a vertical a'crank'arm extending from said} rock shaft means, means pivotally' connecting the outer end of said crank arm to said belt, and means for driving said "belt to'th'ereby effect reciprocation of said slides and hence also said rock shaft means and blade, said rock shaft means being thrown from one position to the-other by-the throw of said crank arm each time the pivotally connected end of the latter passes around each of said discs to thereby throw said blade into and out of contact, respectively with the surface of said filter screen.

3. Apparatus for stripping lint-like material from a filter screen as defined in claim 2 wherein the means securing said wiper blade to said rock shaft means includes spring means extending therebetween for loading the edge of said blade against the screen surface.

4. Apparatus for stripping lint and like material from a fiat filter screen through which air is adapted to be passed under pressure comprising a vertical frame having said filter screen attached thereto, said frame including a pair of side members provided with longitudinally extending guides, a slide disposed in each guide, coaxial horizontal rock shafts carried respectively by said slides, a wiper blade at the air intake side of said screen carried by and secured to said rock shafts for rocking movement with the latter to bring the blade edge into or out of contact with the surface of said screen, a flexible drive at each side of said frame for the associated slide, each side drive including a belt occupying a vertical plane extending transversely to the axis of said rock shafts extending longitudinally of said frame and running on rotatable discs disposed respectively at the top and bottom of said frame and a crank arm having one end pivotally attached to a connection point on said belt and the opposite end secured fast upon the associated rock shaft, and means for driving said belts to thereby cause said slides to be reciprocated in said guides and effect reciprocation of said rock shafts and blade across the face of said screen, said rock shafts and blade being thrown from one position to the other by the throw of said crank arm each time the pivoted end of the latter passes around on of said discs.

5. Apparatus for stripping lint and like material from a flat filter screen through which air is adapted to be passed comprising a vertical frame having said filter screen secured there- 7 to, said frame including frame members at each side thereof provided with longitudinally extending guides, a slide disposed in each guide, rock shaft means journalled in said slides and extending transversely of said frame, a wiper blade extending between said slides and supported upon said rock shaft means, a flexible drive at each side of said frame, each said drive including a belt occupying a vertical plane extending transversely of the axis of said rock shaft means and running on rotatable discs disposed respectively at the top and bottom of said frame, the axes of said discs occupying a vertical plane containing the axis of said rock shaft means and a crank arm, means pivotally connecting one end of each said crank armrto correspondingly located points on said belts, the other ends of said crank arms being secured fast upon opposite ends of said rock shaft means, and means for driving said belts in the same direction and at like speeds to thereby cause said slides to be reciprocated in said guides and effect reciprocation of said rock shaft means and wiper blade across the face of said screen, said rock shaft means and blade being moved by the throw of said crank arms to eifect engagement between the blade edge and screen each time the pivotally connected ends of said crank arms pass around the discs at the top of 8 said frame and to disengage the blade edge from said screen each time the pivotally connected ends of said crank arms pass around the discs at the bottom of said frame.

6. Apparatus for stripping lint-like material from a filter screen as defined in claim 5 and which further includes torsion spring means intermediate said wiper blade and rock shaft means, said wiper blade being carried by said spring means and adapted to be loaded by the latter into pressure contact with the surface of said screen as said crank arms are thrown to the blade engaging position.

JANIES F. KING, JR.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Germany Jan. 23, 1913

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