EP0000467B1 - Spiked rakes with cleaning device for sewage treatment plants - Google Patents

Description

The invention relates to a bar rake with rake cleaner for wastewater treatment plants, with a carriage which can be moved up and down in parallel guides for rakes, a rake mounted on the carriage by means of swivel arms for cleaning the rake, which by means of the swivel arms between two positions, namely an engagement position on the rake and a release position can be pivoted at a distance from the rake, an articulated lever which has a pivot point on the carriage and a pivot point on the pivot arm and can assume an extended position and a bent position which are assigned to the two positions of the rake and with one in the movement path of the Articulated links arranged lower stop, through which the articulated lever can be moved from one position to the other at the end of the downward travel of the carriage, whereby the rake located in the release position when the carriage is traveling downward is pivoted into the engaged position by the change in position of the articulated lever and during the Au is kept in this direction.

A rake with rake cleaner of this type is known from DE-PS 1 252 150. The articulated lever is arranged so that it is stretched during downward travel and the rake is locked in the release position and is bent by the fixed stop when the lower reversal point is reached, so that the rake can pivot into the engaged position. This rake is first swung in under its own weight. In addition, the traction means driving the car can be deflected on the car and anchored to the swivel arm of the rake, so that it pulls the rake against the rake with an additional force which corresponds to the weight of the car and the rake when the upward movement begins.

With such cleaning rakes which pivot in against the rake due to their own weight, there is a risk that the pivoting force of the rake is not sufficient to completely grasp goods which have already washed onto the rake. In particular, it may happen that the rake only penetrates the floating material during its upward travel, when the full weight of the car can affect the rake via the traction means, so that uncleaned remains of the floating material remain at the base of the rake.

The object of the invention is to improve a rake with rake cleaner of the type mentioned in such a way that the pivoting-in movement of the rake takes place with sufficient force and in a transverse movement to the rake running completely in the region of the lower reversal point, and that the upward movement only begins when the rake is completely swung in.

This charge is achieved according to the invention in that the extended position of the articulated lever is assigned to the engagement position and the articulated position to the release position and the rake is positively supported against the carriage in the engaged position by the extended articulated lever.

This has the advantage that the articulated lever does not simply release the rake, as in the known devices, for pivoting in by its own weight, but is stretched by its impact on the stop and inevitably forces the rake into the engaged position with very strong spreading forces , this spreading force when approaching the extended position is a multiple of the force with which the articulated lever hits the stop. The swiveling-in movement of the rake is complete when the carriage has reached its lower reversal point so that the rake is completely grasped and taken away from the screenings from the start of the upward journey. During the ascent, the rake is inevitably held in the engaged position by the extended articulated lever, so it cannot come out of engagement with the rake due to random obstacles.

Swiveling of the rake, which is completely independent of the weight of the rake and the trolley, is obtained if a drive is used which also exerts a driving force on the trolley when it descends. In the known devices, the downward travel of the car takes place under its own weight in accordance with the release of the traction means by the drive. Furthermore, it is particularly advantageous according to the invention if the distance between the pivot point of the rake from the rake and the extension path of the articulated lever are dimensioned and coordinated with one another such that the pivoting-in movement of the rake with the downward movement of the carriage results in a substantially straight-line movement approximately transversely to the plane of the Computed overlay.

The inevitable movement de Harke achieved according to the invention when swiveling brings in addition to the described advantage, however, also with the risk that when hitting obstacles excessive loads on the mechanical construction and; Drive the screen cleaner can act, since the rake can not avoid these loads by swinging out, as in the known devices. Therefore, in an advantageous embodiment of the invention, an overload protection device which switches off the drive is provided for both drive directions of the carriage.

Further advantageous features of the invention emerge from the subclaims. In particular, it enables the invention Construction of a rake cleaner in an advantageous manner to solve the problem of insufficient support of the rake bars in rakes with freely projecting bars. For this purpose, it is provided according to the invention that above the rake with the swivel arms orde the support means are provided, which rest in the lower rest position of the carriage and the rake on the bars of the rake.

• Fig. 1 zeigt den Rechen mit Rechenreiniger in schematischer Seitenansicht, wobei in vollen Linien die Eingriffsstellung und strichpunktiert die Freigabestellung der Harke dargestellt ist.
• Fig. 2 zeigt schematisch den Bewegungsablauf beim Einschwenken der Harke.
• Fig. 3 zeigt eine Überlastsicherung für den Antrieb.
• Fig. 4 zeigt einen schematischen Schnitt nach der Linie IV-IV von Fig. 1.

An embodiment of the invention is explained in more detail with reference to the drawings.

• Fig. 1 shows the rake with rake cleaner in a schematic side view, the full position and the dot-dash line shows the release position of the rake.
• Fig. 2 shows schematically the sequence of movements when pivoting the rake.
• Fig. 3 shows an overload protection for the drive.
• FIG. 4 shows a schematic section along the line IV-IV of FIG. 1.

The rake 1 consists of numerous parallel vertical bars, which are only anchored to the bottom 2 of the flow channel or the like and, moreover, freely project upwards without mutual connection or support. In a guide 3 parallel to the rake 1, a carriage 4 with rollers 5 is guided up and down. The carriage 4 is connected by a link 6 to a rotating drive chain 7 which rotates at the bottom around a deflection roller 8 and at the top around a drive roller (not shown) driven by a reversible geared motor. The drive is reversible, so that the chain exerts a positive driving force on the carriage 4 both during the ascent and the descent. The carriage 4 extends over the entire width of the rake 1, and the guide 3 can consist of two guide rails on both sides of the carriage 4, or, if it is a relatively narrow rake 1, a centrally arranged rail with preferably Double T-shaped profile, which is surrounded by the carriage 4 in a U-shape.

At both ends of the carriage 4 angled pivot arms 11 are mounted in pivot bearings 10, which extend substantially downward and carry the rake 12 at their lower end for cleaning the rake 1 of washed-up material. The rake 12 consists of a beam connecting the two swivel arms 11 and tines 13 projecting therefrom.

By swiveling the swivel arms 11 in the swivel bearings 10, the rake 12 can be moved upwards into an engagement position in which the tines 13 reach through the bars of the rake 1 (shown in full lines in FIG. 1) and for the downward movement into a release position. in which the tines 13 are at a distance from the rake 1 (shown in broken lines in FIG. 1). The device shown in the exemplary embodiment is an undercurrent rake in which the rake is arranged on the downstream side of the rake and detects the floating material on the upstream side through the rake. However, the invention can also be applied in an analogous manner to rakes which are arranged on the upstream side of the rake.

The pivoting in and out of the rake 12 is controlled by an articulated lever 15, which consists of two links 16, 17, which are connected to one another in a joint 18 and one of which is at 19 on the swivel arm 11 and the other at 10 on the carriage 4 is stored. The handlebar 17 mounted on the carriage 4 has an extension 21 projecting beyond the bearing 20 and an extension 22 projecting beyond the joint 18 with a stop 23 cooperating with the other link 16.

The articulated lever 15 interacts with a lower stop 25 and an upper stop 26. The lower stop 25 consists of a roller which is mounted on a bracket 27 connected to the guide 3. The upper stop 26 also consists of a roller which is mounted on a lever 28 which is pivotally mounted at 29 on an arm 30 connected to the guide 3 such that it can be pivoted upwards in the direction of arrow 31 from the horizontal position shown can while it is supported downwards by a stop 32. The upper stop 26 is arranged so that it cooperates with the extension 21 of the handlebar 17, while the lower stop 27 is arranged so that it cooperates with the handlebar 17 and its other extension 22.

Since the articulation point 20 of the articulated lever 15 on the carriage 4 is further away from the rake 1 than the articulation point 19 on the swivel arm 11, the swivel arm 11 and thus the rake 12 are pressed in the direction of the rake by stretching the articulated lever 15 while the articulated lever is buckling 15 corresponds to a movement of the rake 12 away from the rake 1 into the dot-dash position. The swivels of the swivel arms 11 in both directions are dampened by a double-acting shock absorber 33, which is arranged between the bearing point 19 on the swivel arm 11 and the carriage 4. Articulated lever 15, stops 25, 26 and shock absorber 33 can either be assigned to one of the swivel arms 11 only on one side of the carriage 4 or, particularly with wide rakes, can be provided on both sides of the carriage 4 and assigned to both swivel arms 11.

The device works as follows: When the carriage 4 is moving downward, the articulated lever 15 is in the bent position, so that the swivel arms 11 and the rake 12 from. Rakes 1 are swung out. This pivoting can be done in a simple manner in that the center of gravity of the pivot arms 11 and the rake 12 relative to the pivot bearing 10 so far to the left in FIG. 1 is relocated that with released swivel arms 11 these swing away with the rake 12 so far from the rake 1 until the center of gravity is perpendicular to the bearing point 10. Of course, other means, for example connected to the drive chain 7, are also possible in order to move the rake out of engagement with the rake 1. Also, if the position of the center of gravity does not allow automatic swinging out, the articulated lever itself can be used to inevitably disengage. In this case an additional locking device is required.

At the end of the downward travel, the extension 22 of the handlebar 17 runs onto the stop 25, whereby the articulated lever 15 is gradually stretched, the stopper 25 moving along the lower edge of the extension 22 and then the handlebar 17. During the stretching, the leg arms 11 and thus the rake 12 are pressed against the rake with increasing force. When the articulated lever 15 is fully extended and the stop 23 bears against the other link 16, the rake 12 is completely in the engaged position. The articulated lever 15 has been extended slightly beyond the dead center, so that it remains in the extended position by itself during the subsequent upward travel of the carriage 4 and inevitably holds the rake 12 in the engaged position. At the end of the upward journey, the extension 21 of the handlebar 17 passes the upper stop 26, which deviates in the direction of the arrow 31. After the drive has been switched over (which can be brought about by suitably arranged limit switches), the carriage 4 moves downward again, the extension 21 of the handlebar 17 coming from above again onto the upper stop 26, which now cannot deflect and the handlebar 17 pivoted counterclockwise, so that the articulated lever 15 is buckled and the rake 12 can pivot into the release position, which it maintains during the further downward travel, until the handlebar 17 again hits the lower stop.

It can be seen that the pivoting of the rake 12 into the engagement position on the rake 1 takes place by superimposing the downward movement of the carriage 4 with the pivoting of the pivot arms 11 controlled by the extension of the articulated lever 15. By appropriate dimensioning of the distance of the bearing point 10 from the plane of the rake 1 and the lever lengths of the handlebars 16, 17 can, as indicated in Fig. 2, achieve that the superimposition of these movements results in a movement path of the rake 12, which approximately runs straight and approximately at right angles to the rake. This ensures that the rake swivels in exactly at the lower point of reversal and thus ensures that the screenings are completely grasped without any residue.

The overload protection for the drive shown in FIG. 3 has a rocker 35 which is pivotably mounted on the guide 3 and on which the preferably driven, lower deflection wheel 8 of the drive chain 7 is mounted. Instead, such a rocker can also be provided for the upper drive wheel and the drive motor (not shown). The rocker 35 is held by a spring 36 at a predetermined distance from an arm 37 rigidly connected to the guide 3. The spring 36 surrounds a bolt 38 which is articulated on the rocker 35, has an adjustable stop 39 for the spring 36 and is guided on the arm 37 so as to be displaceable. A head 40 of the bolt 37 can actuate a key switch 41 on the arm 37 to switch off the drive motor. This actuation occurs whenever the rake 12 and thus the carriage 4 carrying it are stopped by an obstacle when the chain 7 rotates and then the deflecting roller 8 tends to climb up on the chain to one side or the other while the chain 7 rotates, whereby the rocker 35 and the pin 40 are taken against the force of the spring 36. The spring 36 also serves to keep the drive chain 7 tensioned and also automatically compensate chain elongation.

As can be seen from Fig. 4, 1 side guides 45 are provided at the lower end of the rake, which cooperate with the ends of the rake 12 and ensure that the rake is pivoted into a position in which its prongs 13 with the Align spaces between the bars of the rake 1. This is advantageous because because of the great length and the desirably low profile readiness of the swivel arms 11 transversely to the outflow direction - the swivel arms are normally at rest in the flow cross-section of the channel - these are not very rigid since the rake, so that the rake at Downward travel can be in a laterally offset position relative to the rake, as indicated by dash-dotted lines in FIG. 4. The great length of the swivel arms 11, on the other hand, has the advantage that the entire guide device with the guides 3 and the carriage 4 can be located completely above the water level 46 and even above the upper edge 47 of the lateral boundary walls of the flow channel. No guide niches or the like are therefore necessary in the lateral boundary walls.

The kinked shape of the swivel arms 11 shown in FIG. 1 has the advantage that on the one hand their swivel point 10 can lie at a great distance from the plane of the rake 1, but on the other hand the swivel arms 11 run parallel to the rake 1 essentially over their entire height. This makes it possible to attach support means 11 to the swivel arms, for example in the form of runners running across the entire width of the rake 1 Strips 50 with tines or the like which grip between the bars of the rake 1. If the rake 1 is high, several such support bars can be arranged at different heights on the swivel arms 11. This ensures that the rods of the rake 1 anchored only on the sole 2 of the flow channel can protrude freely and without mutual connection, which is advantageous for the movement of the rake 12 beyond the upper end of the rake and for the free dropping of the screenings is, but the bars of the rake 1 are still sufficiently supported in the area of their upper ends in normal operation when the rake is in the rest position at the lower turning point, if such a support is missing, it could happen that washed-up screenings the gaps between the The bars expand and squeeze through the rake.

The kinked shape of the pivot arms 11 has the further advantage that the bearing point 19 of the handlebar 16 can be arranged offset from the straight connecting line between the pivot bearing 10 and the rake 12 in the direction of the rake 1, whereby a greater length of the articulated lever 15 and thus achieved more favorable power ratios.

The reversible drive for the carriage 4 can also be realized in a form other than the chain 7, e.g. by a rotating driven rope, a V-belt or a toothed belt, by a reversible in the direction of rotation drive spindle with a corresponding spindle nut on the carriage 4, or by a linear motor.

As can be seen from Fig. 1, the tines 13 of the rake 12 have sloping upper edges in the direction of the tips, which enclose an obtuse angle 48 with the bars of the rake 1, as a result of which a certain lifting and loosening of the rake is already performed when the rake is swiveled in Screenings reached, this falling upper edge of the tines 13 also makes it easier to scrape off or throw off the screenings taken along at the upper turning point.

In 'the described embodiment, the center of gravity of the rake and its swivel arms is arranged such that when the articulated lever bends, the rake is pivoted out by its own weight and held in the release position. In addition, the pivoting out is inevitably supported by the articulated lever, as long as its extension 21 abuts against the stop 26 from above and is pivoted by the latter. However, it is also possible to arrange the center of gravity of the rake differently and to force the swiveling out exclusively by means of the folding articulated lever, the extension 21 being dimensioned to be correspondingly long. In this case, i.e. if the rake is not in the equilibrium position in the release position, a detent or lock must be provided on the articulated lever or on the rake arm, which would have to be released again at the end of the descent before the articulated lever was extended.

A particular advantage of the rake cleaner described is that the rake in its normal rest position between the cleaning processes is already in engagement with the rake foot at the lower point of reversal. This has several advantages. The rake starts after switching on the drive, which e.g. can be triggered by a congestion meter, immediately with cleaning; the problem that the rake tines have to pass underneath the material washed up on the rake foot during standstill does not arise. Nor can it occur in winter that screenings freeze on the tines of the rake and then prevent the rake from engaging.

Claims (11)

1. A bar screen with a screen cleaner for waste water treatment installations, comprising a carriage (4) up- and downwardly movable in guide means (3) parallel to the screen (1), a rake (12) pivoted to the carriage by means of pivot arms (11) for cleaning the screen, said rake being pivotable by means of the pivot arms between two positions, namely a position of engagement with the screen and a position of disengagement spaced from the screen, a foldable lever arrangement (15) having a pivot point (20) at the carriage (4) and a pivot point (19) at the pivot arm (11) and being capable of assuming a straightened position and a folded position corresponding to the two positions of the rake, and a lower stop (25) arranged in the path of movement of the foldable lever arrangement (15) for moving said foldable lever arrangement from its one position into its other position at the end of the downward movement of the carriage (4), whereby said rake (12), which is in the position of disengagement during the downward movement of the carriage, will be pivoted by the change of position of the foldable lever arrangement (15) into the position of engagement and held in this position during the upward movement, characterized in that the straightened position of the foldable lever arrangement (15) is associated to the position of engagement, and the folded position is associated to the position of disengagement of said rake, and said rake (12) in the position of engagement is positively supported against the carriage by the straightened lever arrangement (15).

2. A bar screen with screen cleaner according to claim 1, characterized, by a connection (6) between the drive (7) and the carriage (4) for transmitting the drive force even during the downward movement of the carriage.

3. A bar screen with screen cleaner according to claim 1 and 2, characterized in that the distance of the pivot bearing (10) of the pivot arms (11) from the screen (1) and the distance of travel needed for straightening the foldable lever arrangement (15) are so dimensioned and coordinated that the pivot movement of the pivot arms (11) superimposed with the downward movement of the carriage (4) results in a substantially rectilineal movement of the rake (12) transversely to the plain of the screen (1

4. A bar screen with screen cleaner according to claim 1, characterized in that the foldable lever arrangement (15) is adapted to be folded by engaging with an upper stop (26) during the' downward movement of the carriage (4) for pivoting the rake (12) into the disengaged position, that upper stop (26) being capable to yield upwardly.

5. A bar screen with screen cleaner according to one of the claims 1 to 4, characterized in that the upper stop (26) and/or the lower stop (25) cooperates with the lever (17) of the foldable lever arrangement (15) which is pivoted to the carriage (4) or with extensions (21, 22) of this lever (17) extending over its pivot points (20, 18).

6. A bar screen with screen cleaner according to claim 1, characterized in that the folded lever arrangement (15) is pivoted to a part of the pivot arm (11) which projects towards the screen with respect to the straight connecting line between the pivot bearing (10) and the rake (12).

7. A bar screen with screen cleaner according to claim 1, characterized in that the centre of gravity of the rake (12) with the pivot arms (11) is so positioned with respect to the pivot bearing (10), that the rake (12) assumes a position of disengagement spaced from the screen (1) when the foldable lever arrangement (15) is in the folded position and the pivot arms (11) are hanging freely.

8. A bar screen with screen cleaner according to claims 6 or 7, characterized in that each pivot arm (11) has an angled configuration and comprises a part extending substantially parallel to the screen (1), when the rake (12) is in the position of engagement, and a part extending at an angle to that first mentioned part towards the pivot bearing (10).

9. A bar screen with screen cleaner according to one of the claims 1 to 8, characterized in that the upper edges of the teeth (13) of the rake engaging between the bars of the screen (1) form an obtuse angle (48) with the bars of the screen (1) when viewed in the direction of movement towards the screen.

10. A bar screen with screen cleaner according to one of the claims 1 to 9, characterized in that the rake (12) is disposed on the downstream side of the screen (1) and the teeth (13) of the rake pass through the screen (1) for engaging the matter retained by the screen.

11. A bar screen with screen cleaner according to one of the claims 1 to 10, that screen consisting of bars which are anchored only at the bottom of the water duct and project freely upwardly without being further supported against each other, characterized in that above the rake (12) there are provided support means (50) connected with the pivot arms (11) or with the carriage (4), said support means bearing against the bars of the screen (1) when the carriage (4) is in its lower position, which is preferably the resting position.

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