DE29608107U1 - Coarse dirt retention device - Google Patents

Description

bgu-Environmental Protection Systems GmbH B 5276

74626 Bretzfeld

Coarse dirt retention device

The invention relates to a coarse dirt retention device for overflows in reservoirs/basins of sewerage systems, with a rake arranged on the overflow threshold, which contains slots or long holes extending parallel to one another in vertical planes.

Screens of the type described above are used in overflow openings or above overflow thresholds of storage basins to hold back coarse dirt particles from being discharged into the drainage channel leading to the receiving water and to feed them to the sewage treatment plant together with the wastewater. Since such screens gradually become clogged by retained dirt particles, they must be regularly maintained and freed of dirt particles, for which special cleaning devices are provided, which not only entail considerable structural effort, but also require electrical supply lines to control and drive the cleaning device.

The invention is based on the object of improving a coarse dirt retention device of the type described at the beginning in such a way that it can be manufactured with only minimal structural effort and is easy to install, is largely maintenance-free and is capable of regular, effective self-cleaning without external energy.

According to the basic idea of the invention, this object is achieved by

that the rake is pivotably mounted with one end above the overflow threshold and rests on the overflow threshold with its other end due to its own weight,

that a rake having tines engaging in the slots or elongated hole openings of the rake and mounted upstream of the overflow can be pivoted between an upper end position in which the tines penetrating the rake are located at the upper end of the slots or elongated hole openings and a lower end position in which its tines are located at the lower end of the rake,

and that a float activated by the basin dam is in a fixed drive connection with the rake via a float arm mounted coaxially to it in such a way that the rake assumes its upper end position before and during an overflow event, from which it returns at the end of the

During an overflow event, debris is removed from the rake by swinging its tines downwards.

Due to the swivel bearing of the rake, it is guaranteed that in the event of extensive relocation it will swing out automatically under the water pressure exerted by the basin dam, thus effectively preventing the exceeding of a limit water level in the basin. However, such extensive relocation of the rake is almost always an exception in the case of the retention device according to the invention, since the rake is automatically cleaned by the rake without any external energy every time the overflow threshold is triggered.

When the basin fills, the float, which is firmly connected to the rake, is caught by the rising water level and the rake moves with its tines to the upper end position in the rake, even before the water level reaches the height of the overflow threshold. During the entire relief period (overflow period), the rake remains in its upper end position. If the water level falls below the upper edge of the threshold, the rake moves downwards under its own weight in accordance with the movement of the float and clears the rake slots or the dirt adhering to the rake bars with a sheering movement. If the

If the rake is nevertheless moved during an overflow event in such a way that the pool level exceeds the storage target, the rake will swing out under the water pressure and, after swinging out, will immediately return to its original support position on the upper edge of the sill under its own weight.

Further advantages and merits of the coarse dirt retention device according to the invention are evident from the subclaims and from the following description of an exemplary embodiment in conjunction with the drawing. Therein, each schematically,

Fig. 1 shows a coarse dirt retention device according to the invention installed in a reservoir in front of its overflow threshold and

Fig. 2 shows a section of Fig. 1 showing the coarse dirt retention device with the rake pivoted upwards under the water pressure of the basin dam.

According to the drawing, in a wastewater storage basin 10, which is limited by an overflow sill 12 opposite a drainage channel 14 leading to the receiving water, above the sill 12 a re-

chen 16 is installed, which contains parallel slots or long holes extending in vertical planes, for example formed by bars or slats (flat steel plates) and possibly spacers. The rake 16 is pivotally mounted at its upper end near the top of the basin on a horizontal axis 18 running perpendicular to the plane of the drawing, so that its lower end rests on the overflow threshold 12 due to its own weight.

The bars or slats of the rake 16, including the spacers arranged between them, can be fixed to one another by a tie rod 20 extending across the lower end of the rake or by a rake frame (not shown). The rake is preferably inclined downwards due to its upper pivot axis 18, which is arranged offset above the basin to the overflow threshold, so that its slots/openings are located above the basin. If the rake has become clogged with dirt particles due to laying, it pivots automatically due to the water pressure acting on it and reaches the opening position shown in Fig. 2 with solid lines, in which the laying is washed away into the overflow channel 14, whereupon it immediately returns to the starting position due to its own weight.

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For the purpose of cleaning the screen 16, which is mandatory after each overflow event, a rake 22 is provided which can be pivoted about a horizontal axis 24 arranged upstream of the screen's bearing point 18. The pivot axes 18 and 24 are arranged as close as possible to the top of the basin outside the limit water level in order to avoid the accumulation of dirt particles.

The rake 22, including the tines 26 extending over approximately half its front length and engaging in the slots or elongated hole openings of the rake 16, is a flat, stiffened component in the embodiment shown, but can also have other suitable shapes and profiles as required. A float arm 28 which is firmly connected to the rake is also mounted on the pivot axis 24 of the rake 22 and which, according to the drawing, has an arm section 32 which is firmly connected to the rake and aligned in the same direction as it, as well as an arm section 34 which is angled downwards and to which a float 30 is attached.

The float 30 can also be attached to two identically designed float arms 28, which are arranged on both sides of the rake 22. The upper arm sections 32 can be firmly connected to the rake.

be connected or form a firmly braced unit which forms part of the rake or from which the tines 26 of the rake extend.

The position of the float and float arm shown in Fig. 1 with broken lines applies to a dry weather phase or a state in which the pool dam has not yet reached the float 30. In this state, the rake can still be slightly engaged with the rake 16 with the ends of its tines 26 and rest on the overflow threshold 12, although this end position can also be defined by an additional stop (not shown) for the float arm 28. When the pool dam level rises, the rake 22 is moved by the buoyancy force of the float 30 into its upper end position shown in Fig. 2 with solid lines, in which its tines 26 rest on the upper end of the slots or slot openings of the rake 16. The rake only returns from this upper end position at the end of an overflow event.

A cable that extends over the basin is attached to the float arm 28 or to the rake, with which the rake can be moved by hand independently of the floater's movements.

Claims (7)

Expectations 1. Coarse dirt retention device for overflows in reservoirs/basins of sewage systems, with a screen arranged on the overflow threshold, which contains parallel slots or slotted openings extending in vertical planes,
characterized, that the rake (16) is pivotally mounted with one end above the overflow threshold (12) and rests on the overflow threshold with its other end due to its own weight, that a rake (22) having tines (26) engaging in the slots or long holes of the rake (16) and mounted upstream of the overflow can be pivoted between an upper end position in which the tines (26) penetrating the rake are located at the upper end of the slots or long holes, and a lower end position in which their tines are located at the lower end of the rake, and that a float (30) actuated by the basin dam is in a fixed drive connection with the rake via a float arm (28) mounted coaxially to it in such a way that the rake (22) before and during a of an overflow event, it assumes its upper end position, from which it removes retained dirt from the rake by swinging its tines downwards at the end of the overflow event. 2. Coarse dirt retention device according to claim 1, characterized in that the bearing point (18) of the rake (16) is arranged above and upstream of the overflow threshold (12) and the rake rests under its own weight in a downwardly inclined position on the overflow threshold (12) so that its slots/openings are located above the basin (10). 3. Coarse dirt retention device according to claim 1 or 2, characterized in that the direction of extension of the rake tines (26) in their upper end position runs at a downward incline deviating from the horizontal by a small angle. 4. Coarse dirt retention device according to one of the preceding claims, characterized in that the float (30) is connected to at least one float arm (28) which has an arm section (32) extending from the common pivot axis (24) and aligned with the rake and an arm section (34) angled downwards which the float, always located below the rake (22), engages. 5. Coarse dirt retention device according to one of the preceding claims, characterized in that the length and direction of the float arm (28) are dimensioned such that the float (30) is located below the upper edge of the overflow threshold (12) in both the lower and the upper end positions of the rake (22). 6. Coarse dirt retention device according to one of the preceding claims, characterized in that the lower end position of the rake (22) is determined by a fixed stop arranged in the basin and/or by resting the tine ends (26) on the overflow threshold (12). 7. Coarse dirt retention device according to one of the preceding claims, characterized in that a manually operable cable pull engages the rake.