EP0239892A1 - Method and device for operating a vacuum sewer plant - Google Patents

Abstract

1. Method of operating a vacuum sewage plant having at least one vacuum sewage conduit connected to a vacuum station, and having on the premises from which sewage is to be removed a plurality of sewage collecting containers each of which is connectable to said conduit by means of a shutoff valve, each shutoff valve being opened at a specific maximum water level in the collecting container and closed again after a specific period of time during which sewage and air flow into the sewage conduit, characterised in that the actuation points in time of the shutoff valves are adjusted, in dependence on the negative pressure in the sewage conduit, by the negative pressure itself, such that on increasing absolute pressure in the sewage conduit the opening time, associated with a specific quantity of sewage, for the admission of air into the sewage conduit is prolonged and/or the shutoff valves are opened at a relatively low water level in the collecting container.

Description

The invention relates to a method for operating a vacuum sewage system with at least one vacuum sewage line connected to a vacuum station and a large number of sewage collection tanks, each of which can be connected via a shut-off valve, on the plots to be drained, each shut-off valve being opened at a specific maximum water level in the collection tank and after a certain period of time, during which the wastewater and air flow into the wastewater pipe, is closed again, as well as vacuum wastewater systems operated according to this method, as z. B. are described in DE-PS 24 62 295 and DE-GM 85 24 447.

In the known systems, the shut-off valves always open at the same water level in the reservoir regardless of the fluctuating negative pressure and the opening time is also constant. It is dimensioned such that, in addition to the wastewater drawn off from the collecting containers of the house connections, a total of about 2 to 15 times the volume of air is sucked into the vacuum wastewater line. It has been shown in practice that with such a water / air ratio, a municipal sewage system with relatively small pipe cross sections, in which the sewage is transported in the form of a plug, functions permanently, the so-called "simultaneity factor", ie the simultaneous opening of several shut-off valves, plays an important role.

Usually the negative pressure in the sewage pipe is strongest near the vacuum station and decreases noticeably towards the end of the sewage pipe. Despite this pressure gradient, the opening times of the shut-off valves of the house connections have so far been set to an average value and only subsequently corrected in exceptional cases. This is partly due to the fact that the control devices of the shut-off valves are prefabricated in series and are not already assigned to a specific house connection during manufacture. And while installing an individual setting of the opening time of the shut-off valve would be difficult because it could only be established during a _{longer-'Geren} operating time, which is the optimal opening time for the shut-off valve at a particular house connection.

The evenly set opening time of all shut-off valves, irrespective of their position on the sewage pipe and the frequency and simultaneity of the opening processes of the other shut-off valves upstream and downstream, has the consequence that normally too much in the vicinity of the vacuum station, on the other hand at the ends of the line little air is sucked into the pipe system. Due to the larger volume of air flowing into the sewage pipe near the vacuum station, the negative pressure is further reduced towards the end of the pipe, especially if there is more than one between a straight-opening house shut-off valve and the vacuum station in the sewage pipe, which is usually laid with incline and slope sections There are water plugs that seal the line cross-section and must be accelerated. The inflowing air causes an increase in pressure under these circumstances, which not only leads to the vacuum station from the open house connection, but also to the vacuum station Propagated end of line.

The invention is therefore based on the object of providing a method of the type mentioned at the outset which leads to more uniform pressure conditions in the vacuum sewage line and thus to more reliable operation of the entire system with the possibility of increasing capacity.

The above object is achieved in that the switching times of the shut-off valves are adjusted as a function of the negative pressure in the waste water line by the negative pressure itself in such a way that with increasing absolute pressure in the waste water line the opening time associated with a certain amount of waste water for admitting air into the Waste water pipe is extended and / or the shut-off valves are opened when the water level in the collecting tank is lower.

The new method offers the advantage that automatically more air is admitted into the sewage pipe with increasing distance from the vacuum station in accordance with the desired pressure gradient. The lower air intake in the vicinity of the vacuum station also leads to a lower weakening of the negative pressure in the outer line area. The larger amount of air flowing in there is used more economically, since on its longer journey to the vacuum station it also transports the water plugs in the sewage pipe near it.

Another advantage of the new method is that the described functional improvement is not achieved through time-consuming planning or lengthy adjustment work during the installation and maintenance of the shut-off valves, but rather results from the fact that it is connected to the house connection at a certain time in the Waste water line negative pressure serves as a parameter for the opening time of the shut-off valve. This both fluctuations in operating conditions due to the randomness of the opening Processes of all the house connections opening into the sewage line as well as the different position of the individual house connections along the sewage line are taken into account at the same time, so that there is generally no longer any need for special corrective interventions in the control devices of the individual shut-off valves.

Various measures are available for carrying out the method according to the invention. If one assumes that when the shut-off valves are temporarily opened, a constant amount of water is sucked out of the sewage collecting tank of the house connections, because the opening is triggered at a certain water level in the collecting tank and the sewage accumulated therein is completely sucked out, so changes in the Opening duration of the shut-off valve only the amount of air admitted to the pipe in addition to the waste water. For this purpose, it is proposed in a preferred embodiment of the invention that when the shut-off valve is actuated by means of a control valve, the opening time can be changed by an actuator acting on the control valve as a function of the pressure in the vacuum sewage line.

In the case of known control devices for the shut-off valves, their opening time has hitherto been determined by the duration of the throttled ventilation of a cavity which is under negative pressure. In a preferred practical embodiment of the invention it is provided that the opening width of the throttle opening of the cavity can be changed in such control devices by the actuator according to the invention. In order to rule out undesirable influences of short-term extreme pressure fluctuations in the sewage line, a damping element which reacts slowly to pressure peaks is expediently arranged between the actuator and the vacuum sewage line, which in be a particularly simple version is a hollow chamber connected to the vacuum sewage pipe via a throttle opening.

If, in a known manner, the duration of the opening of the shut-off valve is determined by the duration of the throttled ventilation of a cavity which is under vacuum and variable in volume with a movable boundary wall which is preloaded with a force counteracting the vacuum, an alternative to the first proposed change can be found the opening width of the throttle opening of the cavity can also be provided that the path of the boundary wall and / or the force loading it can be changed by the actuator. For example, the actuator acted upon by the negative pressure of the sewage line can adjust a wedge-shaped or step-shaped stop member, which then also limits the path of the movable boundary wall of the cavity in accordance with the adjustment path.

If the movable boundary wall of the cavity is loaded by spring force, the preload force of the spring can also be changed by means of the actuator according to the invention, for example by adjusting a spring bearing by screwing. With a stronger negative pressure, a correspondingly more prestressed spring then leads to a faster return movement of the movable boundary wall during the throttled ventilation of the cavity and thus to a shorter opening time of the shut-off valve.

As an alternative or cumulatively to the above-mentioned measures for influencing the amount of air let into the line in addition to a certain amount of waste water when a shut-off valve is opened, the amount of waste water to be extracted can also be influenced according to the invention. For this purpose, it is proposed in a preferred embodiment of the invention that using a pneumatic control device for each Each shut-off valve, in which the wastewater rising in the collecting container exerts pressure against a diaphragm against a preload directly or via an air volume enclosed in a riser pipe, by the movement of which a switching valve preloaded on a relatively small control surface with the negative pressure of the wastewater line can be switched over, the area of the Membrane is at most about 60, preferably 50 times as large as the control surface of the switching valve. According to this proposal, the water / air ratio is influenced in the desired manner that more wastewater has to accumulate in the collecting tank with a stronger negative pressure before the shut-off valve opens in order to draw off the large volume of water. In other words, the shut-off valves of the house connections near the vacuum station open less frequently for the same amount of wastewater and then let more water into the line than the shut-off valves at the outer end of the line. The advantageous property of the system can also be achieved in that the membrane is arched downward by a weight, a spring or another preload acting from above when the collection container is empty and triggers a switching operation when it is caused by the rising water in the collection container or an air cushion trapped above this has been pushed up into the horizontal central position or only a little beyond. Then, unlike in the case of a diaphragm arched upwards, its increasing support at the edge is not yet noticeably noticeable.

The suggestions made here automatically adjust the system operated with negative pressure to the operating conditions in the sewage pipe that change with the accidental opening of the house connections. However, it is advisable to limit the adaptation to a weakening of the negative pressure by extending the opening duration of the shut-off valves. For this purpose it is provided in a preferred practical embodiment of the invention that when using a throttled ventilatable cavity as a timing element, a movable boundary wall of the cavity with a certain minimum force is loadable, which determines the minimum degree of negative pressure in the negative pressure sewage line, at which the boundary wall can be moved into an end position and thereby a switching operation of the control valve causing the shutoff valve to be triggered can be triggered.

In order to reduce the damaging consequences of an unfavorable pressure distribution in the waste water line, measures can also be taken on the waste water line itself in a further expedient embodiment of the invention. From DE-PS 26 41 110 z. B. an uneven, sawtooth-like course of the vacuum sewer in the area of the house connections is known. This should ensure that even with negative pressure gradients in the line, the wastewater flowing in from a house connection is not conveyed in the reverse direction by the inflowing air. However, it was previously considered necessary for this that the line sections laid with a gradient in the direction of flow are at least approximately twice as long as the adjoining rising line sections and are correspondingly less inclined. With the dimensions realized in practice, namely a gradient of about 10-25cm on sections of length of around 25m, horizontal tolerances and unplanned sinks or pockets resulted from small tolerances in the earthworks and slightly sagging plastic pipes. They could neither guarantee the intended free fall flow in the direction of the vacuum station nor the "dead running" of the water flowing backwards in the event of an incorrect pressure gradient in the desired manner.

However, it has now surprisingly been found that the flow behavior of the wastewater in the line is significantly improved if the rising and falling sections of the line are approximately the same, each with approximately 10-15 m, at the height difference of approximately 10-25 cm which is common in practice long. The greater gradient then promotes the flow to the vacuum station, and a larger amount of water cannot remain over a longer, essentially horizontal section which sweeps the air away or a very large, difficult to accelerate water plug closes the pipe cross-section. On the other hand, the gradient is still flat enough that a gush of water, which is driven back only by relatively small pressure differences, runs dead on it. This latter problem is also alleviated to the extent that, according to the proposals described above, the amounts of water and air let into the line are varied in accordance with the locally different pressure conditions.

• Fig. 1 und 2 den oberen bzw. unteren Teil einer Steuervorrichtung für das Absperrventil eines Hausanschlusses an einer Unterdruck-Abwasserleitung;
• Fig. 3 bis 5 Alternativen zu Fig. 2;
• Fig. 6 in schematischer Darstellung eine abwechselnd mit ansteigenden und abfallend geneigten Abschnitten verlegte Unterdruck-Abwasserleitung im Bereich mehrerer Hausanschlüsse.

The invention is explained below with reference to the drawing. Show it:

• Figures 1 and 2, the upper and lower part of a control device for the shut-off valve of a house connection on a vacuum sewer line.
• Fig. 3 to 5 alternatives to Fig. 2;
• Fig. 6 shows a schematic representation of an alternately laid with rising and falling inclined sections vacuum sewer in the area of several house connections.

The control device shown with its upper part in Fig. 1 and with its lower part in Fig. 2 is used to control the opening and closing movements of a shut-off valve, not shown, as z. B. is described in DE-OS 28 09 431. The shut-off valve separates a relatively small collection container for in a manner known per se at a house connection H. the waste water of this house connection from a vacuum sewage pipe 10 shown in FIG. 4. The collecting tank and the shut-off valve can e.g. B., as shown in DE-PS 28 09 431, may be arranged. If there is a certain amount of waste water, e.g. B. has accumulated in the order of about 8-20 liters, the lower part of the control device shown in FIG. 2 triggers the opening process of the shut-off valve, in which a line 82 is pressurized, which is connected to a diaphragm can 12 in the upper part of the Control device is connected. The diaphragm can 12 is closed at the bottom by a diaphragm piston 14 and, together with it, delimits an essentially closed cavity 16. In the example, the diaphragm piston consists of a disk-shaped, rigid middle part 18 and a cuff-shaped diaphragm which is tightly connected to this and the jacket wall of the diaphragm can 12.

So that the diaphragm piston 14 moves as straight as possible in the vertical direction, its rigid middle part 18 is connected on the upper side to a rod 26 which is guided in a sleeve 28 which is closed at the upper end and extends in the vertical direction. The sleeve 28 is connected to the end wall of the membrane box 12.

A non-return valve 30 is also arranged on the upper end wall of the membrane box 12. It is designed so that when the diaphragm piston 14 is subjected to a vacuum and raised, the volume of air displaced by the diaphragm piston 14 can escape unhindered from the cavity 16. There is therefore no overpressure when the diaphragm piston 14 moves upward in the cavity 16.

The check valve 30 is provided with a small hole that represents a throttle opening. If, after the waste water has been sucked out of the collecting container, the membrane piston 14 is pressed down again by the weight 26, it lowers to the extent and with the speed that it flows into the cavity 16 through the small hole in the check valve 30 Air volume allowed. The opening duration of the shut-off valve between the vacuum drainage line and the collecting container can be determined by suitable selection of the size of the hole in the non-return flap 30. In this way it can be determined whether the shut-off valve operated by the control device shown opens so long that not only the waste water volume accumulated in the collecting container, but also a certain volume of air is subsequently sucked into the negative pressure waste water line. The setting of the throttle opening in the check valve 30 can also be made so that the shut-off valve closes again substantially immediately after the passage of the suctioned waste water. The small amount of inflowing air only needs to be sufficient to allow the wastewater to reach the house connection pipe, which is laid at a slight slope, and which flows into the main pipe that runs along the street. Alternatively, a much longer opening time of the shut-off valve can also be set by means of a smaller hole in the non-return flap 30, so that with each suction process after the wastewater, a multiple of its volume of air is sucked into the vacuum wastewater pipe.

In order to actuate the control valves required to open and close the shut-off valve, a control rod 32 is guided upwards through the end wall of the riser pipe 10. As shown, the lower end of the control rod 32 is received in a longitudinally displaceable manner in a vertical guide 34 which is firmly connected to the rigid middle part 18 of the diaphragm piston 14. Only at the lower end of the guide 34 is the control rod 32 carried along by the membrane piston 14, and only at the upper end of the guide 34 is the control rod 32 carried by the membrane piston 14 downward. In between there is a free vertical movement between the diaphragm piston 14 and the control rod 32, i.e., starting from the position shown, the diaphragm piston 14 must first lift the length of the guide 34 before the control rod 32 is also carried up and moved. In the uppermost position of the control rod 32, a seal 36 seated on it seals the passage opening in the upper end wall of the riser pipe 10 for the control rod 32. Accordingly, when the water level drops and the membrane piston 14 lowers, air can only enter the cavity 16 via the throttle opening in the check valve 30.

In the example, the time switching device consisting of parts 12, 14, 16, 26, 30 controls a valve arrangement consisting overall of a pilot valve 38, a control valve 40 and a pneumatic actuating device 42 for the control valve 40. The input of the pilot valve 38, designated A, is constantly connected to the vacuum sewage line in the flow direction behind the shut-off valve, and is therefore constantly under vacuum. If the diaphragm piston 14 is under pressure by more than that Movement play along the guide 34 lifts, the control rod 32 is carried upwards and opens the pilot valve 38 preloaded by a weight 44. As a result, the negative pressure from the valve connection A propagates through the pilot valve 38 through the valve outlet B into a control line 46, which on the one hand is connected to the valve inlet C of the control valve 40 and on the other hand at E to the pneumatic actuating device 42. In the example case, the control rod 32 is held in its upper position by a mechanical catch 48, which, for example, can have the shape of a spring-loaded ball pressing against a cam on the control rod 32, in which the pilot valve 38 is open.

A similar catch 50 acts on the piston rod of the pneumatic actuating device 42 connected to the valve body of the control valve 40 and represents a certain resistance which the pneumatic actuating device 42 must overcome before the control valve 40 is opened.

Specifically, the pneumatic actuating device 42 in the case of the example consists of an elastic piston 52, for example made of rubber, which rests displaceably but closely against the cylinder wall of the actuating device 42. With sufficient flexibility of the piston 52, it could also be firmly connected to the cylinder wall on the outer circumference. The piston 52 has a larger effective piston area than the end face of the valve body (slide) of the control valve 40 exposed to the negative pressure at the valve inlet C. Since both surfaces are exposed to the same negative pressure of the control line 46, the piston 52 of the pneumatic actuating device 42 pulls the control valve 40 into the Open position upwards as soon as the pilot valve 38 has been opened by the control rod 32, if the negative pressure at port A is sufficient to overcome the resistance to displacement exerted by the catch 50 on the piston rod of the piston 52. So that the snapper 50 the Piston rod of the rubber-elastic piston 52 does not push sideways, are connected to the piston rod above and below the cam denoted by 54 of the catch 50 in the cylinder of the actuating device 42 guided guide disks 56, 58.

As soon as the pneumatic actuating device 42 has pulled the valve body of the control valve 40 upwards into the open position, the negative pressure passes from the valve inlet C to the valve outlet D and from there via a control line 60 to the shut-off valve, which is thereby opened, so that the valve Collection container and riser pipe 10 accumulated waste water is sucked through the open shut-off valve into the vacuum sewer line.

If after the water level of the diaphragm piston 14 drops more or less quickly due to its own weight, the additional weight 26 and possibly a spring load depending on the size of the throttle opening in the non-return flap 30, the control rod 32 is initially still due to the frictional engagement of the catch 48 held in its upper position so that the pilot valve 38 and the control valve 40 remain open until the waste water and possibly a certain amount of air have been sucked into the vacuum sewer line via the shut-off valve. After expiration of the game by selecting the size of the throttle opening in the non-return valve 30 and the weight 26 predetermined period of time for the descent of the _M embrankolbens 14 is the upper end of the guide 34 at the lower end of the control rod 32 to the plant and pulls it by overcoming the resistance of the latch bolt 48 with down. As a result, the valve body of the pilot valve 38 is returned to the closed position. For this purpose, there can be a fixed connection between the valve body of the pilot valve 38 and the control rod 32. However, as shown, an axially displaceable connection between the Valve body of the pilot valve 38 and the control rod 32, such that the valve body is carried upwards in the opening direction by the control rod 32, the holder on the control rod for the valve body engaging, for example, the weight 44 or an axial collar on the valve body, the return of the valve body into its closed position, however, takes place solely by the weight load 44 and the control rod 32 can possibly also be lowered further when the valve body has already reached its closed position, the holder on the control rod 32 guiding it axially sliding along the valve body .

The pneumatic actuator 42 is only provided with a single vacuum connection E in the exemplary embodiment and, in this preferred simple embodiment, is not able to switch the control valve 40 positively back into the closed position. In the example, this switching movement is carried out directly by the control rod 32 by pulling these parts downward via a lever 62 engaging the piston rod of the piston 52 and the valve body of the control valve 40 after the pilot valve 38 has been closed. The lever 62 is connected via a guide 64 with axial play to the control rod 32, which ensures that when the control rod 32 is lifted, the valve body of the control valve 40 is not entrained via the lever 62 and the closing movement of the control valve 40 relative to the closing movement of the pilot valve 38 is somewhat delayed.

Also between the lever 62 and the piston rod of the piston 52 connected to the valve body of the control valve 40, an axially displaceable connection limited by a stop can be provided and a weight load 66 which, after overcoming the displacement resistance by the catch 50 when pulling down the valve body of the control valve 40 through the control rod 32 and the lever 62 returns the valve body to the fully closed position.

At 68, a leak is arranged on the pilot valve 38 and, in a corresponding manner, a leak is also provided at 70 at the control valve 40. These leaks 68 and 70 can e.g. be designed so that a conical pin or stem of the valve body closes a cooperating bore with the valve 38 or 40 open, but with the valve 38 or 40 closed, an annular gap between the conical pin or stem and the bore is open, through which Air can flow into the outlet side of the valve 38 or 40. The air flowing into the control line 46 through the leakage 68 after the closing of the pilot valve 38 eliminates the residual vacuum in the pneumatic actuating device 42, so that the control rod 32 can return the control valve 40 to the closed position. The air flowing into the control line 60 through the leakage 70 after the control valve 40 has been closed eliminates the residual vacuum in the shut-off valve of the vacuum sewage line, not shown, so that the shut-off valve closes again and separates the vacuum sewage line from the sewage collection container of the house.

In the embodiment shown, the valves 38 and 40 and the pneumatic actuating device 42 are arranged one above the other. This need not necessarily be the case. Of course, the control rod 32 can also be angled and / or provided with lateral arms so that the valves 38 and 40 can be arranged side by side or in any other spatial assignment.

1, the line 82 could also be connected to the valve inlet C and the valve outlet D to a controllable ventilation device corresponding to the device 30, 102-124 described below, which is then omitted on the diaphragm box 12. The line 60 branches in this case from the line 46 no longer connected to the valve inlet C.

FIG. 2 shows the lower part of the control device, by means of which a switching operation for opening the shut-off valve is triggered at a certain water level in the collecting container to which the pipe 71 shown in FIG. 3 is connected below. This part of the control device essentially consists of a membrane 72, which is deflected at a certain static water pressure to such an extent that a switching valve 78 is opened via a pin 74 connected to it and a driver 76. This creates a connection between the vacuum and the vacuum -Waste water line 10 in the direction of flow behind the shut-off valve connected vacuum control line 80 and the line 82 already mentioned, which leads into the membrane box 12. As soon as the membrane 14 is pulled up by the negative pressure in the membrane box 12, the switching processes of the control valves 38 and 40 described above then take place.

The switching valve 78 is mounted in an inner tube 84 near the lower end in the example. This inner tube is inserted from above into an outer protective tube 85 which, for. B. can be firmly and tightly connected to the tube 71 as shown in FIG. 3 or introduced from above into the collecting container down to the ground. The inner tube 84 with the switching valve 78 can be pulled up out of the protective tube 85 for maintenance purposes. The end position of the two pipes 84 and 85 can be determined by a stop 86 attached at the bottom but also at the top. An O-ring seal 88 prevents water through the annular gap between the two tubes 84 and 85 upwards z. B. can penetrate into a protective container that receives the upper part of the steier device shown in FIG. 1. The seal 88 could also be attached to the upper end of the tubes 84, 85 so that they can be pushed into one another more easily.

Preferably, the outer protective tube 85 is fixed to the top ge named protective container for the upper part of the control device connected and below z. B. fixed by means of a T-piece on line 71. In the assembled state, held by one or more seals 88, the inner tube 84 is fixed, but detachably, in the outer protective tube 85. At the upper end, the inner tube 84 can protrude from the protective tube 85, and the protective container mentioned can be on this protruding end of the inner tube 84 put on and thereby fixed.

The lower end of the inner tube 84 is through the z. B. rubber membrane 72 completed. In the example according to FIG. 2, the membrane 72 is clamped between an inner flange formed at the lower end of the inner tube 84 and a sleeve 90 inserted from the opposite end of the inner tube 84 and glued in the final position. In this case, the groove for receiving the seal 88 was screwed in after the sleeve 90 had been glued. Alternatively, a 1 inner tube 84 of greater wall thickness can also be used, which is turned radially inward at the lower end, so that the membrane 72 can be inserted into the enlarged bore and then fixed by a glued-in ring.

In the exemplary embodiment shown, a disk-shaped weight 92 is fastened to the pin 74 and, in cooperation with an intermediate wall 94 in the inner tube 84, also acts as a stop. Until it bears against the intermediate wall 94, the weight 92 tends to bulge the membrane 72 downward.

The driver 76 connected to the pin 74 engages the valve member 96 of the switching valve 78. The valve member 96 carries at the lower end a flat seal or a so-called V-ring seal, which is connected to a conical wall area of the valve cooperates sealingly and separates a lower valve chamber 98, which is constantly under vacuum via the line 80, from an upper valve chamber 100 with a larger cross section, which is connected to the diaphragm box 12 via the line 82. The mobility of the valve member 96 and its connection via the driver 76 with the pin 74 are chosen so that in the closed state of the switching valve 78 also the negative pressure acting on the valve member 96 in the valve chamber 98 contributes to the membrane 72 in the same direction as that Weight 92 and the dead weight.

As the water level in the waste water collecting tank rises, the membrane 72 is pressed upwards by the water pressure in line 71 against the aforementioned preload from the initial position, which is arched downward. When the membrane reaches approximately its central, horizontal position, the pin 74 has raised the valve member 96 via the driver 76 to such an extent that the elastic seal in the valve suddenly loses its tight fit on the valve housing and the valve springs open into the open position.

In the exemplary embodiment according to FIG. 2, the membrane 72 is only slightly set back relative to the lowermost edge of the tubes 84 and 85. However, these are pushed up to approximately the flow cross section of the line 71, so that the membrane 72 is flushed directly from the waste water and is cleaned as a result of the rapid flow when the shut-off valve is opened. The embodiment according to FIG. 3 differs from that according to FIG. 2 essentially only in the other type of fastening of the membrane 72. According to FIG. 3, this is seated like a cap on the lower end of the inner tube 84. The edge of the membrane is thickened and engages in an outer annular groove in the inner tube 84, so that the membrane 72 is held reliably. At the same time, this edge forms a seal corresponding to the O-ring seal 88 between the two tubes 84 and 85.

The tubes 84 and 85 can have a diameter of approximately 30 to 100 mm. A diameter range of approximately 30 to 60 mm is preferred, ie the effective diameter of the membrane 72 should be approximately 35 to 45 mm. In relation to this, the surface of the flat seal or V-ring seal on the valve member 96 which is acted upon by the negative pressure of the control line 80 when the switching valve 78 is closed and which preferably has a diameter of approximately 3 to 10 mm, in a preferred practical embodiment 6 mm diameter. The effective area of the membrane 72, which is acted upon by the pressure of the rising water level in the reservoir when the switching operation for opening the shut-off valve is triggered, is thus only about 40 times larger than the area of the valve member 96 of the switching valve which is acted upon as the control area by the system vacuum 78. In contrast to this, in the case of known sewage systems, the membrane area acted upon by the pressure of the sewage rising in the collecting tank was 100 to 200 times as large as the control area of the switching valve acted upon by the system vacuum when opened in the opposite direction. As a result, pressure changes in the sewage pipe have so far not been able to affect the water level in the collection container that is necessary to trigger the switching process. However, if the control surface of the switching valve 78 exposed to the system vacuum and the surface of the diaphragm 72, as proposed here, are brought closer to one another - the earlier, known area ratio differs from this by more than 100% - this forms due to the system vacuum on the valve member 76 effective counterforce such a highly effective factor that changes in the negative pressure in the waste water line and thus also in the control line 80 notice the movement of the membrane 72 as a result of the load from the water level in the collecting container influence. In this way, when the vacuum in the sewage line is stronger, the shut-off valve is only triggered when the water level in the collecting tank is higher, and conversely, a weaker negative pressure in the sewage line causes the shut-off valve to open even with a smaller waste water volume in the collecting tank.

It goes without saying that the switching valve 78 and the diaphragm 72 do not necessarily have to be located in a tube essentially perpendicularly under a protective housing or switch box receiving the upper part of the control device according to FIG. 1. The position of the switching trigger device 72, 78 relative to the upper part of the control device according to FIG. 1 is irrelevant for the function, because the line 82 can be laid anywhere within wide limits. It is therefore also possible to arrange the switching trigger device 72, 78 at the upper end of a riser pipe connected to the collecting container and to actuate it by means of the air volume enclosed therein, which is compressed when the water level rises.

It is also irrelevant whether a switching trigger device according to FIG. 2 is connected upstream of the membrane box 12 at all, which causes the membrane 14 to be raised by the system vacuum supplied via the line 82. Instead, the membrane can 12 z. B. also be the upper end of a dough tube connected to the waste water collecting container or its outlet, so that as the water level in the collecting container increases, the air volume increasingly compressed in the riser pushes the membrane 14 up to triggering the switching operations of the control valves 38, 40. Such an arrangement is e.g. B. shown in DE-PS 24 62 295 and DE-GM 85 24 447. The additional device according to the invention described below in connection with FIG. 1 is suitable for all such control devices which work with a cavity 16 which can be ventilated via a throttle opening as a timing control element for the opening time of the shut-off valve, regardless of how the opening of the shut-off valve is triggered and which others Control valves are connected between the timer and the shut-off valve.

The aim of the invention is to have the changes in the negative pressure in the waste water line take effect as parameters of the opening duration of the shut-off valve. For this purpose, the exemplary embodiment according to FIG. 1 provides an actuating device, designated overall by 102, which influences the width of the throttle opening for venting the cavity 16 as a function of the negative pressure of the waste water line.

The actuating device 102 consists in particular of a hollow chamber 104 in the form of a membrane box, which is connected via a line 106 to the vacuum sewage line 10 and is therefore also constantly under vacuum. The designated 108 membrane of the z. B. attached to the protective housing of the control device diaphragm box 104 is firmly connected to a rack 110 which drives a pinion 112 during axial movement. The shaft 114 of the pinion 112 is rotatable, but axially fixed, z. B. in a attached to the diaphragm box 12 or the protective housing of the control device bearing 116. In the pinion shaft 114 formed as a hollow shaft z. B. by means of a multi-spline connection or a tongue and groove connection, a spindle 118 rotatably but axially displaceably mounted. The outer end of the spindle 118 is threaded and engages in a threaded bore in a pipe socket 120, which in the example forms the air inlet and outlet with a perforated check valve 30 of the diaphragm box 12. When the pinion 112 and the pinion shaft 114 are rotated by the rack 110, the spindle screws more or less into the clear cross section of the ventilation opening 120 of the diaphragm box 12 and changes this and thus also the time period which is decisive for the opening duration of the shut-off valve, while the membrane 14 from the raised or raised position back into the starting shown position drops back by slow, throttled air flows through the air inlet opening 20 into the diaphragm can 12.

In the exemplary embodiment, the elasticity of the membrane 108 is supported by a compression spring 122 which counteracts the negative pressure supplied via the line 106. So that the membrane 108 does not react uneasily to all pressure peaks and rapid changes in the negative pressure in the sewage line, but rather allows the rack 110 to follow the somewhat longer-lasting changes in the pressure level in the sewage line, the line 106 opens into the hollow chamber 104 via a throttle opening 124 1, the principle of the actuating device 102 is only shown schematically. It goes without saying that the actuating device which responds to the negative pressure in the waste water line can be designed differently in detail. For the exemplary embodiment it is only important that the flow cross section of the air inlet into the diaphragm box 12 is changed when the system vacuum is changed. This can e.g. B. also happen in such a way that there are two pipe stubs 120 connecting the inner cavity 16 with the outside atmosphere to the membrane box 12, one of which is provided with a non-return valve 30 and serves as an air outlet opening when the membrane 14 is raised, while the other forms a throttle opening for the air inlet when the diaphragm 14 is lowered, and the opening width of this throttle opening can be changed by the spindle 118 of the actuating device 102. In addition to this air inlet, there may also be another throttle opening in the check valve.

In a further modification of the invention, a piece of hose is provided as the air inlet opening of the membrane box 12 instead of a pipe socket 120, which is compressed to a greater or lesser extent by the adjusting spindle 118 guided in another fixed thread. Alternatively, there is also the further possibility that the air inlet opening for throttled ventilation of the cavity 16 is provided with an inlet valve, the conical valve body of which, for example, is axially adjusted by an adjusting device corresponding to the adjusting device 102 and by means of this axial movement of the valve member with respect to the air inlet opening, the throttling action of the valve in the air inlet opening is changed.

A further embodiment of the invention provides that an air inlet opening with a fixed throttle opening is present on the diaphragm box 12 as before, but additionally a valve is actuated at the end of the stroke movement of the diaphragm 14, which creates a connection between a to the negative pressure via a throttle opening Sewage line connected line and a counter-box covering the underside of the membrane 14 to the membrane box 12. In this modification of the embodiment according to FIG. 1, the system vacuum can therefore be acted upon from both sides, namely during the lifting movement on the upper side and during the descent on the bottom. In this case too, a greater negative pressure in the sewage line leads to a faster lowering movement of the membrane 14 and thus to a shorter opening time of the shut-off valve. It is advantageous that one can do without an actuator with parts that are movable relative to one another. An additional valve is not even required if the negative pressure in the sewage line is connected to one of the control valves, such as e.g. the valve 38 or 40, that is to say for example via a branch line of the control line 46, is brought into connection with the counter box on the underside of the membrane 14.

The time element of the known control devices of the shut-off valves, which is usually present in the form of a membrane box 12, can also be influenced in other ways than by variable throttling of the inflowing or extracted air depending on the system vacuum. Another possibility is, for example, to clamp a compression spring between the diaphragm 14 and the guide bush 28 and, for example on the side of the guide bush 28, the spring bearing by means of an actuator corresponding to the actuator 102 axially towards the diaphragm 14 extendable, so that when the vacuum in the sewage line is stronger, the spring mentioned is more biased and accordingly the diaphragm 14 also returns more quickly from the raised position to the lower position shown.

Yet another possibility is to change the volume of the cavity 16, depending on the strength of the negative pressure in the waste water line, into which air slowly flows in via a throttle opening during the opening period of the shut-off valve. For this purpose e.g. one or more secondary chambers can be connected to the cavity 16 of the membrane box 12, which are also evacuated via the line 82 when the shut-off valve is opened. Depending on the strength of the negative pressure in the waste water line, these secondary chambers can be switched on or separated from the cavity 16 by valves which are actuated as a function of the negative pressure.

Instead of this gradual enlargement or reduction of the cavity 16, a stepless change in its volume can be provided by e.g. by means of an actuator connected to the negative pressure of the sewage line, similar to the actuator 102, a screwable intermediate member of the shift linkage 32, 34 is rotated and thereby its length is changed, so that the switching operation for opening the shut-off valve, depending on the effective length of the intermediate member, is raised or tightened to different heights Position of the membrane 14 is triggered and then a more or less large volume of air must flow into the cavity 16 in order to let the membrane 14 sink back into its lower starting position.

As an alternative to the embodiment described above with a membrane arranged on the underside of the membrane 14, which covers it and during the opening of the shut-off valve with the Sy stem can be subjected to negative pressure, the membrane 14 could also be exposed to the normal air pressure on the underside, but could be connected to the membrane 108 of a hollow chamber 104 with a throttle opening 124, which can be subjected to negative pressure, for example via a rod similar to the rack 110.

To ensure that the shut-off valves only open at a certain minimum vacuum, e.g. Between a spring bearing attached to the control rod 32 at the seal 36 and the upper end wall of the diaphragm box 12, a compression spring 126 of this size can be clamped in such a way that only a sufficiently strong negative pressure is able to move the control rod 32 into its upper end position. Alternatively, a short spring could also be used in the bushing 28 above the guide rod 26, which, like the spring 126, is only effective at the end of the lifting movement of the membrane 14.

4 and 5 show additional devices on the membrane 72, in order to cumulatively or alternatively to the measures proposed above for controlling the maximum water level in the collecting tank, in which the opening of the shut-off valve is triggered, to influence the amount of wastewater sucked off during an opening process. For this purpose, a membrane box 79 is provided, which is connected to line 80 via a branch line 81. 4, the membrane of the membrane box 79 stretches a rubber band 83, one end of which is fixed, while the other is connected to the driver 76 or the pin 74, and a preload on the membrane 72 controlled by the negative pressure in the line 80 exercises. 5, the same effect is achieved in that the membrane of the membrane box 79 presses a compression spring 87 and a flexible disc 89 on the upper end of the pin 74.

The measures dealt with above for better suction of the waste water via a longer negative pressure waste water line with a large number of households or connected to it Other water consumption points, preferably with an amount of air that is two to fifteen times the amount of wastewater, can be supplemented by a new way of laying the vacuum wastewater pipe 10. Since vacuum wastewater systems do not rely on it, a necessary for a sufficient flow rate To create clearances, the management can follow the topographical conditions. It has long been known to form sinks or pockets at certain intervals, in which the wastewater not transported in plug form to the vacuum station converges and again forms plugs closing the pipe cross-section, which then further open when the shut-off valve is opened by the inflowing air Vacuum station. Specifically for the area of house connections, it was previously considered correct according to DE-PS 26 41 110 to lay the vacuum sewage pipe sawtooth with rising and falling sections, the latter being at least twice as long as the rising pipe sections. The disadvantages of this type of cable routing have already been discussed in the introduction. According to FIG. 6, it is now proposed to make the slope sections labeled 10b only about as long as the rising pipe sections 10a. Both sections can each have a length of approximately 10 to 15 m, while the height difference between the high and low points of the line can be approximately 10 to 25 cm. In the known systems according to DE-PS 26 41 110, the gradient sections were therefore 100% longer and the gradient was often too weak in practice. According to the new proposal, there is always enough gradient to form relatively short depressions in which relatively small water plugs, which nevertheless fill the pipe cross section, can form. This advantage also exists if, as suggested above, the opening time of the shut-off valves is not automatically adjusted depending on the fluctuating negative pressure in the waste water line. The suggestion, The slope sections should only be as long as the rising pipe sections, so generally applies to vacuum sewage systems with a water / air ratio of approximately 1: 2 to 1:15. However, the combination of such a line laying with the automatic control of the opening duration of the shut-off valves as a function of the negative pressure in the waste water line described above is particularly advantageous, because then, because of the improved pressure conditions in the waste water line, the risk is even lower that when a shut-off valve is opened from one Water flowing into the sewage pipe due to a local and temporary negative pressure gradient is first sucked in the wrong direction instead of towards the vacuum station.

The type of piping described above is particularly suitable in combination with the method described in DE-OS 35 25 729, according to which each time a shut-off valve is opened, a certain volume of air is admitted into the vacuum line before the waste water and air is mixed with the waste water from the start becomes. If, in addition, throttle openings with an opening width of about 3 to 700 mm ^{2 are} provided on the vacuum line, especially where there are few housings connected over a longer length, which with increasing absolute pressure in the vacuum line - this can in practice, for example, between Vary 0.2 and 0.6 bar - increasingly open and vice versa increasingly close when the vacuum increases, so that regardless of the frequency of actuation of the shut-off valves, depending on the negative pressure in the line, more or less air is admitted into it ensures that the wastewater mixed with air from the outset continues to be continuously bubbled through with air and that overall the water volume at any time in the sinks of the pipe, mixed with air bubbles, is significantly less than with the previously used pipe laying and the like Admitting the whole at all into the sub pressure line let in air in each case in a relatively large amount after each wastewater portion while opening the shut-off valves.

Claims (10)

1.Procedure for operating a vacuum sewage system with at least one vacuum sewage line connected to a vacuum station and a large number of wastewater collection tanks, each of which can be connected via a shut-off valve, on the plots to be drained, each shut-off valve being opened and closed at a specific maximum water level in the collection tank a certain period of time during which the waste water and air flow into the waste water line is closed again, characterized in that the switching times of the shut-off valves are adjusted in dependence on the negative pressure in the waste water line by the negative pressure itself in such a way that with increasing absolute pressure in the Waste water pipe the opening time assigned to a certain amount of waste water for the admission of air into the waste water pipe is extended and / or the shut-off valves are opened when the water level in the collecting tank is lower. 2. To carry out the method according to claim 1 used control device for a shut-off valve on a vacuum sewage pipe, which can be opened by a control valve at a certain maximum water level in a waste water collecting tank and closed after a certain period of time, characterized in that the opening time of the shut-off valve can be changed by an actuator (102) acting on the control valve (12, 40) depending on the pressure in the vacuum sewage line (10). 3. Control device according to claim 2, characterized in that between the actuator (102) and the vacuum sewer line (10) a slow response to pressure peaks attenuator (104, 124) is arranged. 4. Control device according to claim 3, characterized in that the damping member is a via a throttle opening (124) with the vacuum sewer (10) connected hollow chamber (104). 5. Control device according to one of claims 2 to 4, wherein the duration of the opening of the shut-off valve is determined by the duration of the throttled ventilation of a cavity under negative pressure, characterized in that by, the actuator (102), the opening width of the throttle opening (30 , 120) of the cavity (16) is changeable. 6. Control device according to one of claims 2 to 5, wherein the duration of the opening of the shut-off valve is determined by the duration of the throttled ventilation of a vacuum-displaced, variable-volume cavity with a movable boundary wall which is preloaded with a force counteracting the vacuum , characterized in that the path of the boundary wall (14) and / or the force loading it can be changed by the actuator. 7. To carry out the method according to claim 1 used pneumatic control device for a shut-off valve on a vacuum sewage pipe, which is to be opened by a control valve at a certain maximum water level in a waste water collecting tank and to be closed again after a certain period of time, which in Collecting water rising directly or against an air volume enclosed in a riser pipe Preload exerts pressure on a membrane, by means of the movement of which a switching valve preloaded on a relatively small control surface with the negative pressure of the sewage line can be switched over, characterized in that the membrane (72) is arched through to the water surface due to the preload and approximately in the stretched central position Switching valve (78) switches over. 8. To carry out the method according to claim 1 used pneumatic control device for a shut-off valve on a vacuum sewer line, which is to be opened by a control valve at a certain maximum water level in a waste water collecting tank and to be closed again after a certain period of time Collecting water rising directly or via an air volume enclosed in a riser exerts pressure on a membrane against a preload, by means of the movement of which a switching valve preloaded on a relatively small control surface with the negative pressure of the sewage line can be switched over, characterized in that the effective surface of the membrane ( 72) is at most about 60 times as large as the control surface (96) of the switching valve (78) loaded with negative pressure. 9. To carry out the method according to claim 1 used pneumatic control device for a shut-off valve on a vacuum sewer line, which is to be opened by a control valve at a certain maximum water level in a waste water collecting tank and to be closed again after a certain period of time Collecting water rising water directly or via an air volume enclosed in a riser exerts pressure on a membrane against a preload, by moving one on a relatively small Control surface with the negative pressure of the sewage line preloaded switching valve is switchable, characterized in that the membrane (72). is preloaded by a force generated by the negative pressure of the negative pressure sewer line. 10.Vacuum sewage system, in particular for carrying out the method according to claim 1, with at least one vacuum sewage line connected to a vacuum station, alternately laid with rising and falling sections, and a multiplicity of sewage water receptacles which can be connected thereto in each case via a shut-off valve, on the plots to be drained, wherein each shut-off valve is to be opened at a certain water level in the collecting tank and is to be closed again after a certain period of time during which the waste water and air flow into the waste water line, characterized in that the line sections (10b) of the negative pressure waste water line which are laid at a downward direction in the flow direction (10) in the area of the house connections (H) are at most about 20% longer than at least one of the adjacent rising pipe sections (10a).

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