US3358837A

US3358837A - Bar screen cleaning device

Info

Publication number: US3358837A
Application number: US500757A
Authority: US
Inventors: Thomas J Tillett; Auerbach Bedrich
Original assignee: Link Belt Co
Current assignee: Link Belt Co
Priority date: 1965-10-22
Filing date: 1965-10-22
Publication date: 1967-12-19
Anticipated expiration: 1984-12-19
Also published as: JPS4832463B1

Description

Dec. 19, 1967 T J.TILLETT ETAL 3,358,837

BAR SCREEN CLEANING DEVICE Filed Oct. 22, 1965 3 Sheets-Sheet 1 FIGI f THOMAS J. TILLET BEDRICH AUERBACH Q Dec. 19, 1967 J. TILLETT TAL 3,358,837

BAR SCREEN CLEANING DEVICE 5 Sheets-Sheet 2 Filed Oct. 22, 1965 INVENTORS THOMAS J. TILLET BEDRICH AUERBACH Dec. 19, 1967 T. J. TILLETT ETAL 8,

BAR SCREEN CLEANING DEVICE Oct. 22, 3 Sheets-sheet 5 United States Patent 3,358,837 BAR SCREEN CLEANING DEVICE Thomas J. Tillett, Ambler, and Bedrich Auerbach, Lansdale, Pa., assignors to Link-Belt Company, a corporation of Illinois Filed Oct. 22, 1965, Ser'. No. 500,757 9 Claims. (Cl. 210159) This invention relates to a cleaning device for use in clearing screens employed in the removal of large coarse solid materials from a flowing body of liquid.

In many industrial applications such as that encountered in connection with handling sewage and industrial wastes, it is necessary to remove debris and refuse from a flowing stream of liquid. In sewage treating operations, for example, it is desirable to remove the solid debris and refuse from a stream of sewage as it is passing to a settling tank. The removal of such debris and refuse from a flowing stream of liquid is generally accomplished by the use of an inclined screen made up of parallel upstanding bars placed in a conduit or channel through which the stream of liquid flows. Where the liquid is heavily laden with debris and refuse, it is necessary to clean the screen at frequent intervals. In order to accomplish this screen cleaning or clearing in an effective and economical manner, automatic screen cleaning devices are commonly employed.

A major problem which has been encountered in the use of such automatic screen cleaning devices has been to provide effective dumping of the debris and refuse collected from the bar screen by the cleaning device into a discharge outlet. Many of the prior art screen cleaning devices have been beset by the disadvantage of being relatively complex and cumbersome, often requiring substantial head room above the liquid flow stream. Other prior art device have not proved satisfactory in that they have required relatively close supervision and substantial maintenance.

To overcome the disadvantages of the prior art, it is an object of the present invention to provide an improved bar screen cleaning device automatically movable along a guide track which is curved at the upper portion thereof to overlie a discharge outlet in order to achieve effective dumping of the debris collected by the cleaning device.

Another object of the invention is to provide such a screen cleaning device having a raking assembly movable along a guide track which is held between each debris collecting operation in an at rest open position and automatically started on its descending movement along the curved portion of the guide track by spring biased pusher arms.

A further object of the invention is to provide an improved screen cleaning device having cooperating guide and pin means for maintaining a cleaning rake in a closed position until it is properyl disposed above the discharge outlet and means are provided to return the cleaning rake to an at rest open position.

A still further object of the invention is to provide such a screen cleaning device employing automatically releasable latch arms for maintaining the raking assembly in position over the discharge outlet at the end of the curved portion of the guide track while the rake is moving to an at rest open position for the next debris cleaning operation.

Still another object of the invention is to provide an improved screen cleaning device employing limit switches for automatically controlling the movement of the raking assembly along the guide track during the screen cleaning operation.

A further object of the invention is to provide an improved screen cleaning device which is relatively simple and economical in construction.

In general the invention relates to a screen cleaning device for use in combination with a debris and refuse collecting bar screen comprising a guide track adjacent to the screen, said track having a generally straight lower portion and a curved upper portion extending over a discharge point, a rake assembly movable along said track assembly including a rake pivotable into and out of engagement with the screen, means for moving said rake assembly along said track and across said screen, pin means mounted adjacent the curved portion of said track, guide means mounted on said rake engageable with said pin means to prevent said rake from pivoting to an open position until it is positioned over the discharge point, latch means for holding said assembly while said rake is moving to an at rest open position, and pusher means adjacent the curved portion of said track engageable with said rake assembly to initiate descending movement of said rake assembly along the curved portion of said track towards the lower portion thereof.

The above and other objects of the instant invention will become more readily apparent by reference to the accompanying drawings wherein a preferred embodiment is disclosed by way of example, various modifications and changes of details thereof being contemplated within the scope of the appended claims. The apparatus of the invention is illustrated on the accompanying drawings in which:

FIGURE 1 is a vertical sectional view of a screen cleaning device according to the invention showing the rake in open position during its descending movement along the guide track.

FIGURE 2 is a rear sectional view of the screen cleaning device taken along line 2-2 of FIGURE 1.

FIGURE 3 is a vertical sectional view of the screen cleaning device showing the cable in slack position and the rake pivoting to closed position at the bottom end of the guide track.

FIGURE 4 is a vertical sectional view of the screen cleaning device showing the rake in closed position during its ascending movement along the guide track.

FIGURE 5 is a vertical sectional view of a portion of the screen cleaning device showing the raking assembly as it initially contacts the pusher arms with the rake still in closed position just prior to reaching the discharge point for collected debris.

FIGURE 6 is a view similar to FIGURE 5 showing the raking assembly in contact with the pusher arms and the rake in contact with the wiper over the discharge point for collected debris.

FIGURE 7 is a view similar to FIGURE 5 showing the raking assembly in its upper end limit position over the discharge point along the guide track with the rake pivoting toward open position and the latch bars holding the raking assembly in place at the top of the track during this pivoting to open position.

FIGURE 8 is a view similar to FIGURE 5 showing the raking assembly in its at rest open position in readiness for start of its descending movement down the guide track and FIGURE 9 is an enlarged detail perspective view of a portion of the raking assembly.

Illustrated in the drawings is a stream 10 of liquid flowing in the direction of arrow A on FIGURE 1 within channel or conduit 11. Disposed within the channel 11 at an angle of approximately 15 to the vertical is a suitable screen, such as bar screen 12, comprised of a plurality of equally spaced parallel bars 13, for catching debris or refuse in the flowing stream 10 of liquid.

Situated above the bar screen 12 is a housing, generally indicated by the numeral 14, which contains the screen cleaning device to be described more fully hereinafter. The screen cleaning device generally comprises a pair of spaced generally channel shaped guide tracks for guiding the raking assembly 16 along a predetermined path to effect cleaning of the screen and dumping of the refuse so collected into a discharge outlet 17 adjacent the top of housing 14. Each of the tracks 15 is comprised of a straight lower portion 18 generally parallel to the inclined screen 12 and a curved upper portion 19. The tracks 15 are curved rearwardly towards the horizontal at their upper end so that the raking assembly may be effectively carried up and over discharge point 17 in order to properly discharge refuse collected from the screen 12. An adjustable stop member 20 is provided at the bottom of each of the guide tracks 15 for stopping raking assembly 16 when it reaches the bottom of the tracks.

The raking assembly 16 includes a carriage comprised of a pair of sliding blocks 21 adapted for sliding movement within the channels formed by the tracks 15. Each of the blocks 21 is provided with a cover or extension 22 on the inside of the upper end thereof as best shown in FIGURE 9.

Pivotally attached to the upper portion of each sliding block 21 underneath the extension 22 at pivot pin 23 is a rake member 24. Rake member 24 is comprised of a pair of side arms 25 connected by a transverse bar 26 having a plurality of equally spaced teeth 27 as best seen in FIGURE 2. The raking teeth 27 are adapted to mesh with the openings between the spaced bars 13 of inclined screen 12 to effect cleaning of the screen as the rake is drawn upwardly across the screen in a so-called closed position. Disposed on the outer side of each of the side arms 25 of rake member 24 is a curved guide bar 28, the purpose of which will be discussed more fully hereinafter.

The raking assembly 16 is moved along the guide tracks 15 by means of cables 31 wound upon a pair of power driven drums 32. The cables 31 are attached to the raking end of rake member 24 by being connected to the transverse bar 26 at spaced points along the length of bar 26 and inwardly of side members 25. The cable drums 32 are mounted on a shaft 33 situated adjacent the top of housing 14. Motor 34 is operatively connected to shaft 33 by suitable drive means such as chain 35 extending around a sprocket 36 mounted on shaft 33.

A wiper blade 37 extends between and is attached to the sides of housing 14 at a point above the discharge outlet 17 and below the rearwardly curved portions 19 of tracks 15. Wiper blade 37 functions to clean the rake teeth 27 of rake member 24 to discharge debris into the discharge outlet 17.

Pivotally attached to the sides of housing 14 at points between the upper curved portions 19 of tracks 15 and discharge outlet 17 are a pair of spring :biased pusher arms 38. The pusher arms 38 are biased to pivot downwardly by a pair of tension springs 39 attached to the pusher arms and the sides of the housing 14. The pusher arms 38 function to initiate descending movement of the raking assembly 16 along the curved portions of the tracks 15 at the start of each screen cleaning operation.

A pair of latch bars 41 are pivotally attached to the sides of housing 14 above the guide tracks 15 adjacent the top of the housing. One of the latch bars 41 is provided with an upwardly extending bar 42 Which is adapted to contact and actuate a limit switch 43 mounted on theside of the housing just above the latch bar. The actuation of limit switch 43 stops motor 34, terminating winding on cable drums 32 of cables 31 at the end of each screen cleaning operation leaving the rake assembly in an at rest position ready for the next cleaning operation. Alternatively, switch 43 may be connected to recycle the cleaning device by reversing the direction of motor 34, starting unwinding of cable from drums 32 and permitting the raking assembly 16 to descend to the :bottom of the guide tracks 15. Where switch 43 stops the cleaning device the next screen cleaning operation may be initiated by a manual pushbutton or a timer adjusted for periods of 3 to 120 minutes between cycles. With either the pushbut- 4 ton or timer the device will be restarted to unwind cable and lower the raking assembly 16.

Also attached to one side of housing 14 adjacent the top thereof at a point beneath one of the cable drums 32 is a slack cable limit switch assembly 44 having an arm in contact with one of the cables 31. Limit switch assembly 44 operates to reverse the motor 34 upon slackening of the cables 31 which occurs as the raking assembly 16 comes in contact With the stops 20 at the bottom of guide tracks 15.

A pair of pins 45 are mounted on the sides of housing 14 immediately below the curved portions of guide tracks 15. Pins 45 are positioned approximately midway of the curved portions of guide tracks 15. As best illustrated in FIGURES 5 and 6, the pins 45 engage with guide bars 28 on the side arms 25 of rake member 24 as raking assembly 16 ascends to effectively prevent the rake member 24- from pivoting to its open position until it is properly disposed over discharge outlet 17 and has discharged any refuse collected from bar screen 12.

In operation of the present invention, the raking assembly 16 initially is at a point near the upper end of guide tracks 15 with the rake member 24 in its at rest open position as shown in FIGURE 8. In this position the spring biased pusher arms 38 press against the cover portions 22 of sliding blocks 21 and the wire cables 31 restrain the raking assembly from descending down the guide tracks 15. The rake member 24 is holding latch bars 41 up to keep switch 43 closed in the deenergized condition for the equipment. Upon the activation of the motor 34 the cable drums 32 are rotated to cause the cables 31 to unwind and permit the raking assembly 16 to descend down the guide tracks 15. Start of the raking assembly along the curved portions 19 of tracks 15 is initiated by the action of the spring biased pusher arms 38. After the raking assembly moves around the more nearly horizontal segments of curved portions 19, it contmues its descent down the steeply inclined straight portion of the track guides 15 by gravity. During this downward descent, the cable connections to the rake member 24 are in front of the rake pivot points 23 relative to the position of winding drums 32 as shown in FIGURE 1, thus causing the rake tobe held pivoted in an open position by the tension on cables 31.

As the raking assembly 16 reaches the bottom of the guide tracks 15 the sliding blocks 21 contact the lower stops 20 and thereafter the cables 31 go slack by contmued unwinding of cable from drums 32. The slacking of cables 31 permits the rake member 24 to swing from ts open position into engagement with the bar screen as is shown occurring in FIGURE 3. The pivotal movement of the rake at the bottom of guide tracks causes the cable connections to shift to the rear of the rake pivot points 23. T1118 latter shifting of the cable connections causes the rake member to be maintained in closed position when cables 31 are rewound onto drums 32 as the raking assembly ascends the guide tracks 15 to clean screen 12. The slacking of cables 31 also operates slack cable limit switch assembly 44 thus causing the motor 34 to reverse and commence winding cables 31 back onto the drums 32. This pulls the rake member 24 against and up the bar screen 12 with teeth 27 passing between the screen bars 13 to eifect cleaning of any debris or refuse collected by the screen.

As the raking assembly 16 ascends and enters the curved portions 19 of the guide tracks 15, the extensions 22 of the sliding blocks 21 contact the pusher arms 38 (see FIGURE 5) and extends them against the force of the tension springs 39. Thereby the pusher arms are moved to their loaded position in readiness to assist initial movement of the raking assembly 16 in starting its next cleaning operation. As the raking assembly 16 moves through the curved portion of the guide tracks 15 the pivot points 23 of rake member 24 shift to be disposed forwardly of the path of cables 31 (see FIGURE 6) so that the pull of the cables tends to pivot the rake member to the open position. To prevent premature opening of rake member 24, the guide bars 28 on side arms 25 of rake member 24 contact pins 45. These pins act to prevent the rake from swinging to open position until it has discharged the debris into the discharge outlet 27 as shown in FIGURES and 6. As the rake is held in closed position by the guide bars 28 and the pins 45, the rake member passes beneath wiper blade 37 which functions to clean any remaining debris from the teeth 27 of rake member 24.

As the guide bars 28 clear the pins 45, latch bars 41 drop down to engage the ends of slide blocks 21 and hold the raking assembly 16 at its upper limit position (see FIGURE 7). The latch bars 41 serve to hold the raking assembly 16 at its upper limit position until the rake member 24, having cleared the pins 45, under the tension of cables 31 pivots back to its open position. During this swinging to open position the rake member 24 pushes up the latch bars 41 to release the raking assembly -16 for descending movement. As latch bars 41 are pushed upwardly by the rake member 24, limit switch 43 is actuated by stop 42 on one of the latch bars to either recycle or shut oil? the machine. Also raising of latch bars 41 releases them from their hold on rake assembly 16 whereupon pusher arms 38 move rake assembly 16 slightly forwardly of the latching ends of latch bars 41 in readiness for the next screen cleaning operation. In this condition cables 31 are holding the rake assembly 16 against being started in its descent by the remaining spring force of springs 39 acting through pusher bars 38 against assembly 16.

It is apparent that the screen cleaning device of the present invention aflFords many advantages over other prior art screen cleaning devices. For example, the curved upper portion of the guide tracks permits the rake to be efiectively positioned over the discharge outlet for effective disposal of any debris or refuse collected by the rake from the screen. Moreover, the cooperating pins and guide bars effectively prevent the rake from swinging to open position until it is properly disposed to discharge the refuse through the discharge outlet. The spring biased pusher arms 38 also provide effective means of initiating descending movement of the raking assembly around the curved portion of the guide tracks. Thus, the pins, guide bars, spring biased pusher arms, and latch bars effectively cooperate to permit utilization of the curved guide tracks in order to achieve an etfective dumping or discharge of debris collected by the rake.

In addition, the connecting of the cables at the raking end of the rake member, in conjunction with the curved and inclined guide tracks, permits the pivot points of the rake to be shifted forwardly and backwardly of the cables so that the rake is held in open position during descending movement and in closed position during ascending movement.

Although the present invention has been illustrated and described with reference to a specific embodiment, it will be understood that various changes and modifications in the arrangement of parts and components may be made by persons skilled in the art without departing from the spirit or scope of the invention which is defined by the appended claims.

We claim:

1. A screen cleaning device for use in combination with a screen to catch debris or refuse in a flowing liquid stream comprising:

guide track means adjacent to the screen to be cleaned having a generally straight lower portion and a curved upper portion extending over a discharge point,

a rake assembly movable along said track means including a rake member pivotable into and out of engagement with the screen,

means for moving said rake assembly along said track means and across the screen,

pusher means adjacent the curved portion of said track means engageable with said rake assembly to initiate descending movement of said rake assembly along the curved portion of said track means toward the lower portion thereof,

and latch means operable to retain said rake assembly against said pusher means incident discharge of debris from said rake member and movement of said rake member to an at rest open position in readiness to start another screen cleaning operation.

2. A screen cleaning device as defined in claim 1 wherein said pusher means comprises spring biased pusher arm means.

3. A screen cleaning device for use in combination with a screen to catch debris or refuse in a flowing liquid stream comprising:

guide track means adjacent to the screen to be cleaned having a generally straight lower portion and a curved upper portion extending over a refuse discharge point,

a rake assembly movable along said track means including a rake member pivotable between an open position out of engagement with the screen and a closed position to cleaningly cooperate with the screen,

pin means stationarily mounted adjacent the curved portion of said track means,

guide means mounted on said rake member engageable with said pin means to prevent said rake member from pivoting from said closed position to said open position until it is positioned over said discharge point,

and. latch means operable to retain said rake assembly incident pivotal movement of said rake member from said closed position to an at rest open position in readiness to start another screen cleaning operation.

4. A screen cleaning device as defined in claim 3 wherein said guide means comprises a guide bar mounted on the side of said rake means.

5. A screen cleaning device for use in combination with a screen to catch debris or refuse in a flowing liquid stream comprising:

pin means stationan'ly mounted adjacent the curved portion of said track means,

pusher means adjacent the curved portion of said track means engageable with said rake assembly to initiate descending movement of said rake assembly along the curved portion of said track means towards the lower portion thereof,

and latch means operable to retain said rake assembly against said pusher means incident discharge of debris from said rake member and pivotal movement of said rake member from said closed position to an at rest position in readiness to start another screen cleaning operation.

6. A screen cleaning device as defined in claim 5 where in said pusher means comprises a pair of spring biased pusher arms.

7. A screen cleaning device as defined in claim 5 wherein said pin means comprises a pair of pins mounted adjacent the curved portion of said track means and said guide means comprises a pair of guide bars mounted on the sides of said rake member.

8. A screen cleaning device for use in combination with a bar screen to catch debris or refuse in a flowing liquid stream comprising:

a guide track adjacent to the screen having a generally straight lower portion and a curved lower portion extending over a discharge point,

a rake assembly movable along said track including a rake member pivotable into and out of engagement with the screen,

a pair of power operated cables connected to said rake member for moving said rake assembly along said track and across the screen, said cables being connected to the raking end of said rake member to hold said rake member out of engagement with the screen during descending movement of said raking assembly and to maintain said rake member in sliding engagement with the screen during ascending movement of said raking assembly,

pin means stationarily mounted adjacent the curved portion of said track,

guide means mounted on said rake member engageable with said pin means to prevent said rake member from pivoting from a closed screen cleaning position to an open position until said rake member is positioned over the discharge point,

latch means adjacent the curved portion of said track engageable with said rake assembly to hold said assembly in position over the discharge point at the end of the curved portion of said track during pivotal movement of said rake member to said open position,

and pusher means adjacent the curved portion of said track engageable with said rake assembly to initiate descending movement of said rake assembly along the curved portion of said track towards the lower portion thereof.

9. A screen cleaning device for use in combination with a bar screen to catch debris or refuse in a flowing liquid stream comprising:

a guide track adjacent to the screen having a generally straight lower portion and a curved upper portion extending over a discharge point,

a pair of power operated cables connected to said rake member for moving said rake assembly along said tracks and across said screen, said cables being connected to the raking end of said rake member to hold said rake member out of engagement with said screen during descending movement of said raking assembly and to maintain said rake member in sliding engagement with said screen during ascending movement of said raking assembly,

a pair of pins stationarily mounted adjacent the curved portion of said track,

a pair of guide bars mounted on the sides of said rake member engageable with said pins to prevent said rake member from pivoting to an open position until it is positioned over the discharge point,

a pair of latch bars adjacent the curved portion of said track engageable with said rake assembly to hold said assembly in position over the discharge point at the end of the curved portion of said track during pivotal movement of said rake member to said open position,

and a pair of spring biased pusher arms mounted adjacent the curved portion of said track engageable with said rake assembly to initiate descending movement of said rake assembly along the curved portion of said track towards the lower portion thereof.

References Cited UNITED STATES PATENTS 1,392,647 10/1921 Jones 210159 1,823,823 9/1931 Dundas et al 210159 1,984,891 12/1934 Miick et al 210-159 2,186,790 1/1940 Smyer 210--159 3,152,075 10/1964 Gross 210159 REUBEN FRIEDMAN, Primary Examiner.

F. MEDLEY, Assistant Examiner.

" UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,358,837 December 19, 1967 Thomas J. Tillett et a1.

It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 1, line 36, for "device" read devices line 55, for "properyl" read properly column 5, line 6, for "27" read l7 column 7, line 8, for "lower" read upper Signed and sealed this llth day of February 1969.

(SEAL) Attest:

EDWARD J. BRENNER Edward M. Fletcher, Ir.

Commissioner of Patents Attesting Officer

Claims

5. A SCREEN CLEANING DEVICE FOR USE IN COMBINATION WITH A SCREEN TO CATCH DEBRIS OR REFUSE IN A FLOWING LIQUID STREAM COMPRISING: GUIDE TRACK MEANS ADJACENT TO THE SCREEN TO BE CLEANED HAVING A GENERALLY STRAIGHT LOWER PORTION AND A CURVED UPPER PORTION EXTENDING OVER A DISCHARGE POINT, A RAKE ASSEMBLY MOVABLE ALONG SAID TRACK MEANS INCLUDING A RAKE MEMBER PIVOTABLE BETWEEN AN OPEN POSITION OUT OF ENGAGEMENT WITH THE SCREEN AND A CLOSED POSITION TO CLEANINGLY COOPERATE WITH THE SCREEN, MEANS FOR MOVING SAID RAKE ASSEMBLY ALONG SAID TRACK MEANS AND ACROSS THE SCREEN, PIN MEANS STATIONARILY MOUNTED ADJACENT THE CURVED PORTION OF SAID TRACK MEANS, GUIDE MEANS MOUNTED ON SAID RAKE MEMBER ENGAGEABLE WITH SAID PIN MEANS TO PREVENT SAID RAKE MEMBER FROM PIVOTING FROM SAID CLOSED POSITION TO SAID OPEN POSITION UNTIL IT IS POSITIONED OVER SAID DISCHARGE POINT, PUSHER MEANS ADJACENT THE CURVED PORTION OF SAID TRACK MEANS ENGAGEABLE WITH SAID RAKE ASSEMBLY TO INITIATE DESCENDING MOVEMENT OF SAID RAKE ASSEMBLY ALONG THE CURVED PORTION OF SAID TRACK MEANS TOWARDS THE LOWER PORTION THEREOF,