Vertical backflow preventer with automatically closed drop flap

Abstract

The invention relates to a tubular backflow preventer for a vertical installation in a waste water pipe gradient, comprising a waste water inlet connection piece; a waste water outlet connection piece, a waste water passage path of the backflow preventer running from the waste water inlet connection piece to the waste water outlet connection piece; and a pivotable drop flap which sealingly interacts with a drop flap opening between the waste water inlet connection piece and the waste water outlet connection piece and which allows a flow of waste water in the direction of the waste water passage path in an open position and blocks a flow of waste water opposite the direction of the waste water passage path in a closed position. The drop flap is automatically closed against the direction of gravity in a normal position when the backflow preventer is in a vertical installation orientation and automatically opens in the direction of gravity in a waste water passage situation. The invention also relates to a waste water lifting system.

Description

[0001] Vertical backwater valve with automatically closed flap

[0002] The present invention relates to a wastewater backflow preventer having the features of independent claim 1 and an associated wastewater lifting system.

[0003] EP2177679A1, for example, discloses a backflow preventer which is also suitable for very contaminated household wastewater, such as wastewater containing faeces.

[0004] Overall, however, it is clear that many common backflow preventers have weaknesses when conveying particularly contaminated wastewater, for example, when conveying wastewater containing feces. In this case, dirt particles can adhere to the movable closing parts of the backflow preventer or the sealing seals, impairing the functionality of these parts and thus the backflow preventer. Therefore, complex design measures are being taken to improve or ensure the function of the backflow preventer in the event of backflow.

[0005] The present invention is based on the object of improving the operational reliability of a wastewater backflow preventer and, at the same time, making the backflow preventer as structurally simple as possible.

[0006] The present invention proposes a tubular backflow preventer for vertical installation in a sewer pipe gradient, comprising a wastewater inlet nozzle and a wastewater outlet nozzle, wherein a wastewater passage path of the backflow preventer runs from the wastewater inlet nozzle to the wastewater outlet nozzle, a pivotable drop flap which interacts sealingly with a drop flap opening between the wastewater inlet nozzle and the wastewater outlet nozzle, and the drop flap allows wastewater to flow in the direction of the wastewater passage path through an open position and blocks it against the direction of the wastewater passage path through a closed position, wherein the drop flap is automatically closed against the direction of gravity in a vertical installation orientation of the backflow preventer in a normal position and opens automatically in the direction of gravity in a wastewater passage situation.

[0007] It has surprisingly been found that an inventive combination of a flap valve that automatically closes in the normal position against the direction of gravity and automatically opens in the direction of gravity, with the ability to install the backflow preventer vertically, creates a particularly reliable wastewater backflow preventer. It has been shown that the wastewater flow hitting the flap valve, which is closed in the normally position, in a wastewater passage situation, cleans the flap valve and the flap valve opening and noticeably reduces and in some cases even prevents the adhesion of contaminants to these functionally relevant components. The pivoting movement of the flap valve in the wastewater flow also helps reduce functionally impairing contamination on the flap valve and the flap valve opening.

[0008] In addition, the vertical installation orientation allows the kinetic energy of the wastewater to be used to efficiently flush the backflow preventer, which reduces dirt deposits and further increases the operational reliability of the backflow preventer.

[0009] Furthermore, the standard closed position of the trapdoor ensures that an air cushion is reliably formed below the closed trapdoor opening in a backflow situation, which makes it possible to position functionally relevant parts of the backflow preventer, such as the trapdoor and the trapdoor opening, in the backflow preventer in such a way that the level of the backflow wastewater does not come into contact with these functionally relevant parts.

[0010] It has been shown that a backflow preventer according to the invention can be used reliably even with particularly problematic wastewater, such as wastewater containing faeces (“black water”), due to the advantages mentioned above.

[0011] In an optional embodiment, the pivot axis of the trapdoor is arranged in the backflow preventer in such a way that, in a wastewater backflow situation, the pivot axis is located in an air cushion formed between the closed trapdoor opening and the wastewater backflow level.

[0012] This protects the functionally relevant swivel axis from contamination by backflow wastewater and increases operational reliability.

[0013] In an optional embodiment, the position of the pivot axis in the backwater valve is determined from a worst-case scenario, specifically from the physical relationship between the air volume available on the outlet side of the backwater valve up to the wastewater outlet nozzle when the flap is closed and the maximum backwater pressure permitted for the backwater valve. The pivot axis is positioned above the maximum possible wastewater backwater level calculated from this.

[0014] In a further optional embodiment, the flap valve is positioned in the backflow preventer such that, in a wastewater backflow situation, the flap valve is located in an air cushion formed between the closed flap valve opening and the wastewater backflow level. The above-mentioned "worst-case" consideration also applies to the arrangement of the flap valve in the backflow preventer in an optional embodiment. This protects the functionally relevant flap valve from contamination by backflow wastewater and increases operational reliability.

[0015] In a further, optional embodiment, the pivot axis of the drop flap is arranged in the vertical installation orientation on the outlet side of the drop flap opening above a lowest point of the drop flap opening.

[0016] If, contrary to expectations, the trapdoor does not close tightly in a backflow situation, this arrangement offers the possibility that the pivot axis still does not come into contact with backflow wastewater in a smaller, remaining air cushion.

[0017] In an additional, optional embodiment, the drop flap can be designed as a first lever arm of a rocker mounted on the pivot axis and a force accumulator on the opposite second lever arm automatically pushes the drop flap into the normal position in the vertical installation situation.

[0018] This allows the energy storage device to be mounted further away from the drop flap opening, thus reducing the risk of contamination that could impair the function of the energy storage device. Furthermore, the lever arms allow for more options regarding the energy storage device variants, such as the choice of a closing weight or a spring element supported on the backwater valve housing.

[0019] In a particularly advantageous, optional embodiment, the energy storage device is a closing weight. A closing weight is a particularly reliable variant for providing a permanent closing force on the drop flap opening via the lever arms of the rocker.

[0020] Optionally, in a further embodiment, the second lever arm can pivot into an escape space of the backflow preventer arranged laterally to the side of the drop flap opening when the drop flap is opened in the vertical installation orientation.

[0021] This protects the second lever arm from contamination by the wastewater jet.

[0022] In a further optional embodiment, the closing weight can pivot into the said escape space.

[0023] This protects the closing weight from contamination by the wastewater jet.

[0024] In an additional optional embodiment of the invention, the escape space can be provided at least in part by an inspection cover.

[0025] This allows the desired escape space to be adjusted, if necessary, simply by changing the shape of the inspection cover, without having to modify other parts of the backflow preventer. Easy access to the second lever arm is also provided if maintenance or inspection is necessary.

[0026] In a further optional embodiment, a stop point defining the fully open position of the trapdoor is arranged such that the stop force at the stop point is directed towards the wastewater inlet nozzle.

[0027] This advantageously directs the impact force towards the inlet nozzle, which in this situation is additionally stabilized by the mass of the incoming wastewater.

[0028] In an optional embodiment of the invention, an elastic element cushions the impact at an attachment point defining the fully open position of the drop flap.

[0029] This prevents wear and tear from impacts and reduces noise. Furthermore, depending on the orientation of the backwater valve—for example, if it is upside down or horizontal before installation—the elastic element can serve as a support and resting point for the open flap.

[0030] In optional embodiments, the elastic element is attached to the backflow housing. In further optional embodiments, the elastic element is attached to the drop flap or to the second lever arm of a rocker comprising the drop flap.

[0031] In a further advantageous embodiment, the trapdoor can optionally have a floating body which, in the event of floating, provides additional closing force in the direction of the trapdoor opening.

[0032] This also increases functional reliability in the event of backflow.

[0033] Optionally, the float is designed as a hollow body. This allows for weight savings and thus reduces the closing force required to maintain the normally closed position.

[0034] It is further advantageous that, in an optional embodiment, the drop flap has a closing element closing the drop flap opening with a convex section which projects into the drop flap opening in the normal position.

[0035] The convex section reduces the risk of dirt adhering to this area and makes it easier to rinse off existing dirt deposits from this area during the opening movement of the drop flap.

[0036] In another optional embodiment, the trapdoor opening is oriented at an angle to the direction of the wastewater flow path and points toward the fully open trapdoor. The angled orientation of the trapdoor opening reduces the travel of the pivoting trapdoors from an open position to a closed position, and vice versa. This allows the backwater valve to open and close more quickly than with a horizontal trapdoor opening, making the system more responsive and reliable.

[0037] In a further, optional embodiment, the drop flap in the vertical installation orientation and in the fully open position protrudes a maximum of 15% of the drop flap opening area projected in the direction of gravity.

[0038] This allows for particularly rapid flushing of the backflow preventer and release of the fall path towards the wastewater outlet nozzle, whereby the drop flap can release a lot of space for the wastewater fall jet.

[0039] The above-mentioned effect improves further at a maximum protrusion of 10%, especially at a maximum protrusion of 5%.

[0040] In a further optional embodiment, the backflow preventer has a sudden wastewater passage area widening at the drop flap opening in the direction of the wastewater passage path.

[0041] A sudden widening of the wastewater passage area in the direction of the wastewater passage path creates a valve effect at the trap door opening, which reduces the adhesion of contaminants in the trap door opening area.

[0042] The higher the pressure of the wastewater above the flap opening, the stronger this valve effect becomes.

[0043] When a pressurised wastewater is installed at the closed trapdoor, the wastewater is transferred to a pressureless gravity drainage system when the trapdoor is opened at the wastewater passage area widening.

[0044] In further optional embodiments, the wastewater passage area for the flowing wastewater expands abruptly by at least 25%, in particular by at least 50%, in particular by at least 75%.

[0045] An optional expansion of at least 25% already reduces deposits particularly well, which can be further increased by expanding by at least 50% and ensures even better results with at least 75%.

[0046] In an advantageous optional embodiment, the internal cross-sectional area of ​​the wastewater outlet nozzle is larger than that of the trapdoor opening. This ensures rapid flushing and drainage of the wastewater through the backflow preventer without wastewater accumulating in the backflow preventer and avoidably contaminating moving parts.

[0047] In an advantageous, optional variant, the internal cross-sectional area is at least 25% larger, optionally even at least 50% larger, than that of the drop-hatch opening, which further enhances the aforementioned effects. This is especially true for the at least 50% variant.

[0048] In a further optional embodiment, the drop flap opening area projected in the direction of gravity in the vertical installation orientation can lie completely within the cross-section of the waste water outlet nozzle.

[0049] This ensures that the backflow preventer is quickly flushed through in the falling wastewater stream and reduces the risk of dirt deposits in the backflow preventer that could impair its function.

[0050] A further, optional embodiment of the invention relates to a particularly reliable wastewater lifting system comprising a backflow preventer according to one of the previous embodiments.

[0051] Here, a wastewater lifting system is proposed, comprising a wastewater lifting plant with a wastewater conveying line, wherein the wastewater lifting plant is designed to pump wastewater through the wastewater conveying line in the wastewater conveying direction from a geodetically lower level to a geodetically higher drainage level, wherein the wastewater conveying line has a riser section in the wastewater conveying direction, a curved line section with a peak level of the wastewater conveying line, and a downpipe section in which wastewater moves in the direction of gravity, the wastewater lifting system further comprising a backflow preventer according to one of the embodiments described here above, wherein the downpipe section has the backflow preventer.

[0052] It has surprisingly been shown that an arrangement in which the downpipe section has the backflow preventer protects the lifting station from excessive backflow of the wastewater column after a lifting activity has stopped. At the same time, the backflow preventer is particularly vigorously flushed with wastewater during lifting operation, thereby protecting it from adhering contaminants and remaining reliably operational. In addition, there are the advantages of the backflow preventer according to the invention already explained here, which together create a particularly reliable wastewater lifting system. In optional embodiments of the aforementioned embodiments of the backflow preventer according to the invention, the main extension axis of the backflow preventer, including the wastewater passage path at the drop flap opening, extends along the vertical in the installation orientation and runs in the direction of gravity.Steep angular deviations of the main extension axis, or at least of the wastewater passage path at the trapdoor opening, in the installation orientation of up to 20° to the vertical, in particular of up to 5° to the vertical, are also included in further embodiments of the invention.

[0053] In optional embodiments of the aforementioned embodiments of the backwater valve according to the invention, the two lever arms of the rocker with the drop flap are arranged at an angle to each other, in particular in a further optional range between 180° and 90°. This allows for particularly space-saving designs of the rocker regardless of the type of energy storage mechanism.

[0054] In further optional versions of all the aforementioned embodiments of the invention, the wastewater conveying line of the wastewater lifting system according to the invention is unvented from the lifting station to the backflow preventer, in particular at least up to the sealing level of the backflow preventer. This improves the backflow-damping effect and the system's response speed due to particularly rapidly building pressure differences.

[0055] In further optional embodiments of all the aforementioned embodiments of the invention, said wastewater conveying line is not ventilated from the lifting station to the point of entry into a hierarchically superior wastewater downpipe, for example into the central wastewater downpipe of a building.

[0056] In further optional embodiments of all the aforementioned embodiments of the invention, the apex level of the wastewater conveying line is geodetically above the local backflow level. In further optional, alternative embodiments of all the aforementioned embodiments of the invention, the apex level of the wastewater conveying line is geodetically below the local backflow level.

[0057] In preferred optional embodiments of the aforementioned wastewater lifting system of the invention, the extension axis of the downpipe section according to the invention extends along the vertical and runs in the direction of gravity. Steep angular deviations of the extension axis of the downpipe section of up to 20° from the vertical, in particular up to 5° from the vertical, are also included in further embodiments of the invention. All of the embodiments described above can be combined with one another as desired.

[0058] The following figures explain the advantages and functions of the invention in more detail with reference to the figures, which show possible embodiments of the invention that advantageously combine the previously mentioned embodiments. Some functionally equivalent features are provided with the same reference symbols for the sake of clarity.

[0059] It shows

[0060] Figure 1 shows a cross section along a central main extension axis of a backflow preventer according to the invention in installation orientation, with the drop flap in a closed normal position,

[0061] Figure 2 shows a cross-section like Fig. 1 with the drop flap in a fully open position,

[0062] Figure Its non-sectioned top view of the backwater valve from Fig. 2, viewed along the main extension axis and in the direction of gravity,

[0063] Figure 4 is a perspective side view of the backflow preventer from Fig. 1, with the inspection cover removed,

[0064] Figure 5 shows an embodiment of a wastewater lifting system according to the invention with a backflow preventer according to the invention.

[0065] Fig. 1 shows a backflow preventer 1 according to an embodiment of the invention. The backflow preventer 1 is shown in its installed orientation, sectioned along its central main extension axis A, which here coincides with the vertical V and is parallel to the direction of gravity S.

[0066] The backflow preventer 1 is designed like a tube, with a wastewater inlet nozzle 2 at its upper end and a wastewater outlet nozzle 3 at its lower end.

[0067] The wastewater passage path 4 of the backflow preventer 1 runs from the wastewater inlet nozzle 2 to the wastewater outlet nozzle 3. In this embodiment, the wastewater passage path 4 runs in the entire backflow preventer 1 parallel to the main extension axis A and, in the installation orientation, parallel to the vertical V and thus in the direction of gravity S.

[0068] In further possible embodiments not shown, the wastewater passage path 4, in sections or completely, and / or the main extension axis A are arranged at an angle to the vertical V in the installation orientation, for example in a range from 0° to 20° to the vertical V, in particular in the range from 0° to 5° to the vertical V. Between the wastewater inlet nozzle 2 and the wastewater outlet nozzle 3, the backflow preventer 1 has a flap opening 5 which, in its normal position, is held tightly closed against the direction of gravity S by a pivotable flap 6 of the backflow preventer 1.

[0069] Fig. 2 shows the drop flap 6 in its fully open position. The drop flap 6 can be pivoted back and forth about its pivot axis X between the fully open position and its standard closed position. A force always acts on the drop flap 6, tending to move it toward the closed position.

[0070] In this embodiment, the drop flap 6 is designed as a first lever arm 8 of a rocker 9 mounted on the pivot axis X. The second lever arm 10 of the rocker 9 in this embodiment has a force accumulator in the form of a closing weight 11, which always presses the drop flap 6 into the closed position in the installed orientation and pivots accordingly with the second lever arm 10 about the pivot axis X.

[0071] The drop flap opening 5 extends in an opening plane F and is surrounded by a drop flap opening seat 7, against which a corresponding circumferential seal 21 on the drop flap 6 in the closed position is sealingly abutted by the closing force provided by the closing weight 11 via the lever arms 10, 8.

[0072] In this embodiment, the trapdoor opening plane F is oriented obliquely to the wastewater passage 4 at this point, here at an acute angle of approximately 20°. As can be clearly seen in Fig. 2, the trapdoor opening 5 points toward the trapdoor 6 in the fully open position.

[0073] As can also be clearly seen in Figures 1 and 2, the pivot axis X is arranged above a lowest point of the drop flap opening 5, here at the level of the highest point of the drop flap opening 5.

[0074] In this embodiment, the first lever arm 8 and the second lever arm 10 are arranged at an angle to one another, whereby an escape space 12 of the backwater valve 1, arranged laterally relative to the drop flap opening 5, can be designed to be more compact laterally for the second lever arm 10 pivoting to the fully open position, in particular for the closing weight 11 arranged at the end of the second lever arm 10. The escape space 12 is partially formed by a dome-like inspection cover 13 of the backwater valve 1. The inspection cover 13 can be removed from the rest of the backwater valve 1 if necessary.

[0075] As can be clearly seen in Fig. 2, the closing weight 11 in the fully open position of the drop flap 6 is in abutment with an elastic element 14, here provided by a part of the inspection cover seal 15. The stop point 16 between the rocker 9, here the closing weight 11, and the housing 17 of the backflow preventer 1 is located here on the elastic element 14 and is selected such that a stop force 18 acting upon stop is directed towards the wastewater inlet nozzle 2.

[0076] In the present embodiment, the drop flap 6 has a closing element 19 with a convexly curved section 20 pointing towards the drop flap 6, here surrounded by the seal 21 of the drop flap 6. As can be clearly seen in Fig. 1, the convex section 20 projects into the drop flap opening 5 in the closed position of the drop flap 6.

[0077] In this embodiment, the closing element 19 is designed as a closed hollow body with a ball-like shape. The hollow body is buoyant. In the present case, the side of the closing element 19 facing away from the drop flap opening 5 is also convexly curved in order to form a hollow floating body with the largest possible volume and thus the highest possible buoyancy.

[0078] As can also be clearly seen in Fig. 2, in this embodiment, a sudden wastewater passage area widening 22 is realized at the trapdoor opening 5 in the direction of the wastewater passage path 4. Here, a sudden widening in the clear width parallel to the trapdoor opening 5 or parallel to the trapdoor opening plane F, in which the trapdoor opening 5 is located. In this embodiment, the trapdoor opening plane F coincides with the sealing plane D, in which the trapdoor 6 seals the trapdoor opening 5 with the seal 21 against the trapdoor opening seat 7 in the closed position.

[0079] In this embodiment, a sudden widening of approximately 90% in the clear width parallel to the drop-flap opening plane F is realized. However, smaller widenings of at least 25% are also conceivable in other embodiments.

[0080] In the embodiment shown, the drop flap opening 5 has a diameter of 63.5 mm.

[0081] In optional embodiments not shown, the diameter of the drop flap opening 5 is in the range of 30mm to 100mm, in particular in the range of 40mm to 70mm.

[0082] The closing force to be overcome by the inlet-side wastewater flow at the closed flap 6 is in possible embodiments in the range of 0.5 Newton to 10 Newton, in particular in the range of 1 Newton to 5 Newton, depending on the area of ​​the flap opening 5.

[0083] In further possible embodiments, the trap flap 6 opens when the wastewater pressure at the inlet side of the trap flap opening 5 is in the range of 0.1 bar to 1 bar, in particular in the range of 0.15 bar to 0.5 bar. The closing weight in this embodiment has a mass of approximately 240 g.

[0084] The maximum backflow pressure permitted for the backflow preventer in this design is 0.5 bar. In other designs, this pressure is in the range of up to 2 bar.

[0085] Fig. 3 shows a view of the backwater valve 1 in the fully open flap position from above along the main extension axis A or the vertical V, and thus in the direction of gravity S. The flap opening 5 can be seen here. As can be clearly seen here, the flap 6 with its convex section 20 in its fully open position protrudes only minimally into the flap opening area 23 projected in the direction of gravity S, here less than 5% of this area 23. Otherwise, in this fully open flap position, the fall path along the wastewater passageway 4 is completely free in the direction of gravity S up to the outlet nozzle 3.

[0086] As the viewing direction in Fig. 3 also clearly shows, the pivot axis X as well as the second lever arm 10 including the closing weight 11 are arranged in the escape space 12 protected towards the drop flap opening 5 and are therefore not visible in Fig. 3.

[0087] As can be clearly seen in Fig. 2, the internal cross-sectional area 24 of the waste water outlet nozzle 3 is larger than that of the trap door opening 5, here by approximately 150%.

[0088] From the combination of Fig. 2 and Fig. 3 it can also be clearly seen that the trapdoor opening area 23 projected in the direction of gravity in the vertical installation orientation lies completely within the cross section 24 of the waste water outlet nozzle 3.

[0089] Fig. 4 shows the backflow preventer 1 in the closed state in a side perspective, with the inspection cover 13 removed.

[0090] Here, one can clearly see the deliberately lateral and high-positioned pivot axis X of the drop flap 6, and also that in this embodiment, the rocker 9, including the pivot axis X, is designed to be replaceable if necessary through the inspection opening 25. The pivot axis X has aligned pins 26, each of which is pivotably held in a receptacle 27 on the backflow housing side. The receptacles 27 are open toward the inspection opening 25, so that the rocker 9 can be removed if necessary.

[0091] Figure 5 shows an embodiment of a wastewater lifting system 28 according to the invention with a backflow preventer 1 according to the invention.

[0092] The wastewater lifting system 28 comprises a wastewater lifting station 29, a wastewater conveying line 30, and the backflow preventer 1. The wastewater lifting station 29 is configured to pump wastewater through the wastewater conveying line 30 or through the wastewater conveying pipeline in the wastewater conveying direction 31 from a geodetically lower level to a geodetically higher drainage level.

[0093] In the present case, the lifting station 29 is designed to pump domestic wastewater, including wastewater containing faeces.

[0094] The lifting station 29 is connected at its pressure outlet to the beginning of the wastewater conveying line 30. The beginning of the wastewater conveying line 30 is formed by a vertically oriented riser section 32, which at its end merges into a curved section 33, which has the apex level N of the wastewater conveying line 30.

[0095] At the end of the curved pipe section 33 viewed in the wastewater conveying direction 31, the curved pipe section 33 transitions into a vertically oriented downpipe section 34, which here has the backflow preventer 1. In the present embodiment, the backflow preventer 1 is arranged at the end of the downpipe section 34.

[0096] In the vertical downpipe section 34, i.e. also in the backflow preventer 1, the wastewater coming from the lifting station 29 during lifting operation moves in the direction of gravity S. Following the wastewater outlet nozzle 3 of the backflow preventer 1, a straight gradient pipe 36 (with a gradient of approximately 2% here) follows via a 45° piece 35, which drains by gravity to a hierarchically superior sewer (not shown), more precisely to the central wastewater downpipe of the building (not shown).

[0097] The wastewater passage path 4 of the backflow preventer 1 forms part of the wastewater movement path of the wastewater conveying line 30.

[0098] In the present embodiment, the lower level of the lifting station 29 is just above the floor 38 of the installation room, here a basement room, and the higher level is at the apex level N of the wastewater conveying pipe 30, which here is just below the ceiling 38.

[0099] In the present embodiment, the riser section 32 is designed as a straight, vertically extending pipe. In embodiments not shown, the riser section 32 extends, for example, in a stair-step fashion, with one or more steps leading upward toward the curved section 33.

[0100] In further possible embodiments not shown, the downpipe section 34 does not immediately follow the curved pipe section 33, but there are further gradient sections of the wastewater conveying pipe 30 between the curved pipe section 33 and the downpipe section

[0101] 34.

[0102] In the following, functions of a backflow preventer 1 according to the invention are briefly explained using the described embodiment.

[0103] The drop flap 6 is in the closed position as standard, whereby the closing weight 11 provides the closing force via the two lever arms 8, 10, which the wastewater pressing on the drop flap 6 on the inlet side must overcome in order for the drop flap 6 to pivot from the closed position towards the fully open position.

[0104] When the trapdoor 6 is opened in the direction of gravity S, a valve effect occurs at the wastewater passage area widening 22, which additionally accelerates the wastewater at this point of the wastewater passage path 4 in the direction of gravity S and in the process cleans the trapdoor opening 5 and the surfaces of the trapdoor 6 facing the trapdoor opening 5, including the seal 21 and the convex section 20, in the falling wastewater jet, or the wastewater jet prevents or at least reduces the adhesion of contaminants to these parts.

[0105] When first opened under a surge of wastewater arriving on the inlet side, it is possible that the flap valve 6, here the closing weight 11, is struck against the closing force up to the stop point 16, wherein in such a case the force 18 of the impact is cushioned by the elastic element 14 and is directed by the selected position of the stop point 16 in the direction of the wastewater inlet nozzle 2 which has just been filled with wastewater mass, which mitigates the stressful effects of the impact on the structure of the backflow preventer 1 and reduces impact noises.

[0106] The second lever arm 10 together with the closing weight 11 move deeper into the escape space 12 during the opening movement.

[0107] However, the closing weight 11 continuously pushes the trapdoor 6 towards the trapdoor opening 5, so that the closing element 19 is cleaned in the wastewater jet during a wastewater passage situation.

[0108] The alignment of the flap opening 5 with the outlet nozzle 3 and the noticeably larger internal cross-sectional area of ​​the wastewater nozzle 24, combined with the flap 6 projecting only slightly into the flap opening area 23 projected in the direction of gravity, ensures that the wastewater flow is efficiently and quickly directed through the backflow preventer 1 when the flap 6 is opened, thus flushing the latter particularly well. As soon as the force of the wastewater surge subsides and becomes less than the closing force, the flap 6 closes the flap opening 5 again.

[0109] In the event of a backflow situation, an air cushion forms in the closed backflow preventer below the sealing plane D, so that in this case, the pivot axis X together with the rocker 9 do not come into contact with the backflow wastewater and thus cannot be contaminated by it. In the case of the backflow preventer 1 shown here, the backflow level is at least still below the escape chamber 12 at the opening of the wastewater outlet nozzle 3. Depending on the installed state of the backflow preventer, the backflow level can also be below or outside the backflow preventer 1 on the outlet side, depending, among other things, on the length of the remainder of the downpipe section 34 adjoining the wastewater outlet nozzle 3 in the wastewater conveyance direction 31.

[0110] Should the drop flap 6 not be completely tightly closed, it is nevertheless very likely in the present case that at least the pivot axis X, with the pins 26 and receptacles 27, due to their upper lateral arrangement, lie in a developing, smaller air cushion and thus do not come into contact with the heavily contaminated backflow wastewater level despite leakage of the drop flap seal 6.

[0111] In the wastewater lifting system 28 shown in Fig. 5, a backflow preventer 1 according to the invention reduces the backflow of the wastewater column onto the lifting station 29 when the lifting operation stops, because a backflow-like backflow or falling of the wastewater column in the riser section 32 against the wastewater conveying direction 31 is prevented by the backflow preventer 1. At the same time, the vertical backflow preventer 1 is particularly advantageously flushed by the pressure of the lifting station 29. Furthermore, at the wastewater passage area widening 22, when the drop flap 6 is opened, a transition of the pressurized wastewater above it into a pressureless and falling gravity drainage takes place. This keeps the backflow preventer 1 particularly clean due to the particularly pronounced valve effect.

Claims

Claims 1. Tubular backflow preventer (1) for vertical installation in a sewer pipe gradient, comprising a wastewater inlet nozzle (2) and a wastewater outlet nozzle (3), wherein a wastewater passage path (4) of the backflow preventer (1) runs from the wastewater inlet nozzle (2) to the wastewater outlet nozzle (3), a pivotable drop flap (6) which interacts sealingly with a drop flap opening (5) between the wastewater inlet nozzle (2) and the wastewater outlet nozzle (3), and the drop flap (6) allows wastewater to flow in the direction of the wastewater passage path (4) through an open position and blocks it against the direction of the wastewater passage path (4) through a closed position, characterized in that the drop flap (6) is automatically closed against the direction of gravity (S) in a vertical installation orientation of the backflow preventer (1) in a normal position and opens automatically in the direction of gravity (S) in a wastewater passage situation.

2. Backflow preventer (1) according to claim 1, wherein the pivot axis (X) of the flap (6) is arranged in the backflow preventer (1) such that the pivot axis (X) is located in an air cushion formed between the closed flap opening (5) and the wastewater backflow level in a wastewater backflow situation, in particular the flap (6) is arranged in the backflow preventer (1) such that the flap (6) is located in an air cushion formed between the closed flap opening (5) and the wastewater backflow level in a wastewater backflow situation.

3. Backflow preventer (1) according to one of the preceding claims, wherein the pivot axis (X) of the drop flap (6) is arranged in the vertical installation orientation on the outlet side of the drop flap opening (5) above a lowest point of the drop flap opening (5).

4. Backflow preventer (1) according to one of the preceding claims, wherein the drop flap (6) is designed as a first lever arm (8) of a rocker (9) mounted on the pivot axis (X) and a force accumulator on the opposite second lever arm (10) automatically presses the drop flap (6) into the normal position in the vertical installation situation, wherein the force accumulator is in particular a closing weight (11).

5. Backflow preventer (1) according to claim 4, wherein the second lever arm (10), in particular the closing weight (11), can pivot when the drop flap (6) is opened in the vertical installation orientation into an escape space (12) of the backflow preventer arranged laterally to the drop flap opening (5), in particular wherein the escape space is provided at least in part by an inspection cover (13).

6. Backflow preventer (1) according to one of the preceding claims, wherein a stop point (16) defining the fully open position of the drop flap (6) is arranged such that the stop force (18) at the stop point (16) is directed towards the wastewater inlet nozzle (2).

7. Backflow preventer (1) according to one of the preceding claims, wherein an elastic element (14) cushions the impact at a stop point (16) defining the fully open position of the drop flap (6).

8. Backflow preventer (1) according to one of the preceding claims, wherein the drop flap (6) has a floating body which, in the event of floating up, provides additional closing force in the direction of the drop flap opening (5), wherein the floating body is designed in particular as a hollow body.

9. Backflow preventer (1) according to one of the preceding claims, wherein the drop flap (6) has a closing element (19) closing the drop flap opening (5) with a convex section (20) which projects into the drop flap opening (5) in the normal position.

10. Backflow preventer (1) according to one of the preceding claims, wherein the trapdoor opening (5) is oriented obliquely to the direction of the wastewater passage path (4) and points towards the fully opened trapdoor (6).

11. Backflow preventer (1) according to one of the preceding claims, wherein the drop flap (6) in the vertical installation orientation and in the fully open position protrudes a maximum of 15%, in particular a maximum of 10%, in particular a maximum of 5% of the drop flap opening area (23) projected in the direction of gravity.

12. Backflow preventer (1) according to one of the preceding claims, wherein the backflow preventer (1) has a sudden wastewater passage area widening (22) at the drop flap opening (5) in the direction of the wastewater passage path (4), in particular a widening of at least 25%, preferably of at least 50%, preferably of at least 75%.

13. Backflow preventer (1) according to one of the preceding claims, wherein the inner cross-sectional area (24) of the waste water outlet nozzle (3) is larger than that of the trapdoor opening (5), in particular at least 25% larger, especially at least 50% larger.

14. Backflow preventer (1) according to one of the preceding claims, wherein the drop flap opening area (23) projected in the direction of gravity in the vertical installation orientation lies completely within the cross section of the waste water outlet nozzle (3).

15. Wastewater lifting system (28), comprising a wastewater lifting plant (29) with a wastewater conveying line (30), wherein the wastewater lifting plant (29) is designed to pump wastewater through the wastewater conveying line (30) in the wastewater conveying direction (31) from a geodetically lower level to a geodetically higher drainage level, wherein the wastewater conveying line (30) has a riser section (32) in the wastewater conveying direction (31), a curved section (33) with a peak level (N) of the wastewater conveying line (30), and a downpipe section (34) in which wastewater moves in the direction of gravity, the wastewater lifting system (28) further comprising a backwater valve (1) according to one of the preceding claims, wherein the downpipe section (34) has the backwater valve (1).

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