EP1737323B1 - Liquid aspirator - Google Patents

Abstract

A liquid aspirator, in particular for liquids containing solids such as sludge, has a receptacle into which liquid can be sucked in by an aspirator motor through a vacuum connector and from which the liquid can drain through a drainage. The receptacle has at least two separate receiving chambers and a control that controls that the receiving chambers are filled alternatingly with liquid while the receiving chambers that are not being filled are drained. The receiving chambers are sealable relative to the vacuum side of the aspirator motor by main valves that are preferably mechanically connected.

Description

The invention relates to a liquid aspirator for sucking or transporting liquids, in particular solids containing liquids such as sludge or the like. Such a liquid sucker according to the preamble of claim 1 is known from DE 102 40 804 A1 known. It has a receptacle in which a vacuum is generated via an air-suction motor. Due to the negative pressure, the liquid or the mud is sucked into the receptacle via a suction port and after filling of the container and switching off the engine via a drain and a discharge element, usually in the form of a hose, run out of the receptacle again and to a desired location be directed.

Such sludge suckers work reliably, since motor damage to moving liquid or sludge through the receptacle prevents engine damage due to entrained solids. However, after each filling of the receptacle, a suction pause is necessary, in which the receptacle is emptied again. The liquid or sludge sucking is therefore relatively time consuming.

The British patent 241 960 already shows a lifting system for water, sewage, sand and the like, which has two lifting tanks, which are alternately filled and emptied. This large-scale, permanently installed system works with the help of a complicated lever mechanism. The actual suction device is spatially widely spaced from the two tanks and connected over long cable routes. The complicated structure of this system is not suitable for smaller, in particular portable liquid aspirator.

The invention has for its object to provide a comparison with the prior art improved liquid aspirator.

According to the invention this problem is solved by a liquid aspirator with the features of claim 1. For this purpose, the receptacle of the liquid aspirator is formed with at least two separate receiving chambers. The main valves are coupled together so as to alternately open and close, and a control is provided by which an alternate filling and emptying of the receiving chambers is introduced with liquid. Thus, the liquid or Schlammsaugvorgang be continued continuously, since always liquid can be sucked into one of the chambers, while another chamber is being emptied and thus creates space for refilling. At the same time, the suction motor is safely protected from contamination by the valves.

Preferably, the liquid aspirator according to the invention operates with two receiving chambers. Each of the receiving chambers may be associated with a separate motor, the controller may simply be designed so that it alternately turns on and off the motors. As a result, the liquid flows from the chamber, whose engine is just turned off under its own weight, while liquid is sucked into the other receiving chamber by the other engine switched on.

In a particularly preferred embodiment, only a suction motor is provided and the circuit is designed so that the suction side of the engine alternately is connected to the various receiving chambers, so that here too the receiving chambers are alternately filled and emptied. The naturally aspirated engine can therefore pass through and is therefore more efficient. In the receiving chamber with which the suction side of the suction motor is currently connected, liquid is sucked into it, while at the other receiving chamber no vacuum is applied, so that the liquid located there can drain under its own weight. Once this chamber is completely or mostly emptied, the process is reversed and this initially emptied chamber connected to the suction side of the suction motor to refill accordingly.

The suction motor can be designed as desired, for example as an air suction or as a vacuum pump.

The control can be done electronically, also as a time control. However, it is preferably designed as a mechanical control or circuit, as can be a low maintenance need and low sensitivity to external influences and possible misuse, such as tilting of the teat, reach.

Fig. 1:

Einen Flüssigkeitssauger mit zwei Motoren im Schnitt,

Fig. 2:

eine Außenansicht einer anderen Ausführungsform mit einem Motor,

Fig. 3:

einen Schnitt in Richtung III-III durch den Gegenstand in Fig. 2,

Fig. 4:

einen Schnitt in Richtung IV-IV durch den Gegenstand in Fig. 2,

Fig. 5:

einen Schnitt in Richtung V-V durch den Gegenstand in Fig. 2,

Fig. 6 bis 11:

den Gegenstand aus Fig. 3 in unterschiedlichen Füll- und Entleerungsstadien,

Fig. 12:

einen Detailschnitt in Richtung XII-XII in Fig. 5, jedoch in einer anderen Ausführungsvariante,

Fig. 13:

einen Detailschnitt entsprechend Ausschnitt XIII in Fig. 6, wiederum in einer anderen Ausführungsvariante,

Fig. 14:

den Gegenstand aus Fig. 13 in einem anderen Füll-/Entleerungsstadium,

Fig. 15:

einen Teilschnitt entsprechend Fig. 3 durch eine andere Ausführungsform des Schlammsaugers der Fig. 2 bis 11 und

Fig. 16 und 17:

eine weitere einmotorige Ausführungsform eines erfindungsgemäßen Flüssigkeitssaugers im Schnitt.

Further advantages and details of the invention will become apparent from the dependent claims and illustrated in the drawings embodiments of the invention, which are described below; show it:

Fig. 1:

A liquid vacuum cleaner with two motors on average,

Fig. 2:

an external view of another embodiment with a motor,

3:

a section in the direction of III-III through the object in Fig. 2 .

4:

a section in the direction of IV-IV through the object in Fig. 2 .

Fig. 5:

make a cut in the direction of VV through the object in Fig. 2 .

6 to 11:

the object out Fig. 3 in different filling and discharging stages,

Fig. 12:

a detail section in the direction of XII-XII in Fig. 5 but in another embodiment,

Fig. 13:

a detail section corresponding to section XIII in Fig. 6 again in another embodiment,

Fig. 14:

the object out Fig. 13 in another filling / discharging stage,

Fig. 15:

a partial section accordingly Fig. 3 by another embodiment of the Schlammsaugers the Fig. 2 to 11 and

FIGS. 16 and 17:

another single-engine embodiment of a liquid aspirator according to the invention in section.

In Fig. 1 schematically a liquid aspirator is shown, which has two separate receiving chambers 1, 2. Each receiving chamber 1, 2 is assigned its own suction motor 3, 4. About the suction motors 3, 4 can in the chambers 1, 2 a Vacuum are generated, whereby liquid can be sucked into the receiving chambers 1, 2 via a suction port, not shown, which opens into the receiving chambers 1, 2 in the upper region. For example, if the receiving chamber 1 filled with liquid up to a predetermined height, the suction motor 3 turns off. Under the weight of the liquid, a negative pressure flap 5 closes the receiving chamber 1 at the bottom and the liquid flows via a drain 7 and an adjoining drainage element, not shown, for example a drain hose. By a control it is ensured that the filling with liquid and the emptying of the receiving chambers 1, 2 takes place alternately, so that liquid is continuously drawn in and discharged via the outlet 7. In the illustrated embodiment, the control is performed by floats 9, 10, which are each held in a guide 11, 12 movable in the vertical direction. The floats 9, 10 represent through their top configuration at the same time valves with which the receiving chambers 1, 2 can be closed against the respective suction side of the motors 3, 4, so that no liquid can be sucked into the motors. The position of the floats 9, 10 is queried via signal generators, such as reed contacts or the like. If a float 9, 10 has reached its upper end position, the signal generator gives the message "chamber full" to a control electronics, which turns off the respective motor 3, 4 and the other motor 4, 3 turns on. However, the motors 3, 4 can also be actuated by suitably mounted switch mechanically by the action of the float 9, 10. A purely time-controlled electronic circuit of the motors 3, 4 is possible.

A particularly preferred embodiment of a liquid aspirator according to the invention is in the Fig. 2 to 11 shown. The exterior view in Fig. 2 shows the housing of the liquid sucker with receptacle 13 and cover 14. A Suction port 15 extends into the receptacle 13 inside.

Fig. 3 shows a central section through the liquid sucker. This has two receiving chambers 1, 2, in which via air intake openings 17, 18 by means of a single suction motor 3 negative pressure can be generated. The suction motor 3 draws in air continuously, while the air intake openings 17, 18 are alternately opened or closed by main valves 19, 20, so that only in a receiving chamber 1, 2, a negative pressure is generated. The alternating opening and closing of the main valves 19, 20 is ensured by a coupling of the main valves 19, 20, which is preferred and less susceptible to mechanical failure. If, as in the illustrated embodiment, the liquid aspirator has two receiving chambers 1, 2, the main valves 19, 20 can be connected in a particularly simple manner via a rocker 21, which is rigid in itself but pivotally mounted. The movement of the main valves 19, 20 is introduced via guides 11, 12 held in a height-flexible float 9, 10. When the float 9 in chamber 1 has been raised to its highest possible position by the liquid sucked in, as shown, it has pressed the main valve 19 and thus opened the main valve 20. The receiving chamber 1 is no longer connected to the suction side of the suction motor 3, so that in her no negative pressure prevails. Due to the dead weight of the collected in the receiving chamber 1 liquid, which is no longer compensated by the negative pressure, a negative pressure flap 5 opens, and the liquid can drain via a drain 7 and a non-illustrated discharge element connected thereto, for example a hose.

In the illustrated embodiment, the emptying of the receiving chambers 1, 2 is still supported by the receiving chambers 1, 2 in the Fig. 4 and 5 shown secondary valves 23, 24 with the outlet side or pressure side of the suction motor 3 are connected. The secondary valves 23, 24 are controlled so that each of the respective receiving chamber 1, 2 associated auxiliary valve 23, 24 is open when the main valve 19, 20 is closed. For example, in the position of the 3 and 4 in the receiving chamber 1 when draining the liquid located there through the exhaust air of the suction motor 3, which penetrates via the opened secondary valve 23 into the receiving chamber 1, an overpressure which accelerates the outflow of the liquid from the negative pressure flap 5. The secondary valves 23, 24 are preferably also mechanically coupled, preferably also via a rocker 25.

Fig. 5 , for the representation of the suction motor 3 has been removed, illustrates the principle of assisted emptying. The rocker 21 of the main valves 19, 20 and the rocker 25 of the secondary valves 23, 24 are connected via a common pivot axis 26 rigidly and only together about this pivot axis 26 pivotally connected and thus mechanically coupled in a simple manner. Thus, it is ensured that main valve 19 and secondary valve 23 of the receiving chamber 1 or main valve 20 and secondary valve 24 of the receiving chamber 2 each alternately open and close. Fig. 5 also shows that the main valves 19, 20 connect to a connected to the suction side of the suction motor 3 slot-like suction chamber 27, while the secondary valves 23, 24 are in a suction chamber 27 enclosing round pressure chamber 28 which is connected to the exhaust side of the suction motor 3 , The exhaust air of the suction motor 3 does not have to be completely discharged via the auxiliary valves 23, 24 and the receiving chambers 1, 2, but can also be partially or completely discharged directly to the environment of the liquid aspirator depending on the requirement.

In a particularly preferred embodiment variant, which is described in detail in FIG Fig. 12 shown is, the outlet side of the suction motor 3, 4 with the receiving chambers 1, 2 via the floats 9, 10 and their guides 11, 12 are connected. This is particularly advantageous when the float guides 11, 12 are surrounded to protect the floats 9, 10 and the main valves 19, 20 against contamination with a net, mesh, mesh, fleece or the like filter. This filter would normally become clogged over time with dirt particles, fine algae or the like and thereby worsen the efficiency of the liquid aspirator. By the application of the blow-out air of the suction motor 3, 4 from the inside of the float guides 11, 12 forth, with each Saugseitenwechsel a small pressure pulse is applied to the filter, which cleans it of dirt particles and other impurities. As in Fig. 12 shown is the pressure chamber 28 at the outlet side of the suction motor 3, 4 side facing away from the secondary valve 24 via a connecting channel 42 with the top of the float 10 and thus the inside of the float guide 12 is connected. The other, not shown side with secondary valve 23 and float 9 is formed accordingly.

In the Fig. 4 and 5 It can be seen that the receiving chambers 1, 2 are arranged in a particularly space-saving manner eccentrically in one another, wherein both receiving chambers 1, 2 have a pressure-favorable substantially cylindrical shape and substantially the same receiving volumes.

The operation of the liquid aspirator is described below with reference to Fig. 6 to 11 clarified. Fig. 6 shows that the main valve 20 of the receiving chamber 2 is opened. In the receiving chamber 2, a negative pressure forms, which is sucked through the suction port 15 and an open check valve 32 liquid, symbolized by open arrows, in the receiving chamber 2. Of the Float 10 is thereby moved with increasing liquid level within its guide 12 upwards. The guide 12 is formed as shown at the bottom of broken, so that liquid can penetrate into the guide 12. In the upper region 12 ', however, the guide 12 is formed circumferentially closed. The float 10 has a seal 33 at its upper outer circumference. As soon as this upper region of the float 10 provided with the seal 33 dips into the upper closed region 12 'of the guide 12, the guide is formed in the upper region 12' which is then closed at the bottom 12 by the suction of the suction motor 3 such a strong negative pressure that the float 10 is torn up from the liquid surface, with its main valve 20 in the form substantially corresponding top hits the main valve 20 and this jerkily pushes up and closes , which opens on the coupling of the main valves 20, 19 via the rocker 21, the main valve 19 of the other receiving chamber 1. This moment is in Fig. 7 shown. The special design of the guides 11, 12 with the top closed areas 11 ', 12' and the float 9, 10 with seals 33 makes it possible in this embodiment to mechanically provide a sufficient impulse that the previously closed main valve 19 (or. in the opposite case 20) against the prevailing in the suction chamber 27 by the suction motor 3 negative pressure still opens.

In the illustration according to Fig. 8 has already formed a negative pressure in the receiving chamber 1, whereby the negative pressure flap 5 has closed. About the suction port 15 and a receiving chamber 1 associated check valve 31 is now indicated by the open arrows liquid sucked into the receiving chamber 1. Meanwhile, there is no negative pressure in the receiving chamber 2 because of the closed main valve 20. By the weight of the Liquid therefore opens the vacuum flap 6 and the liquid flows, symbolized by the filled arrows, out of the drain 7 addition.

The Fig. 9 and 10 show how simultaneously with the emptying of the receiving chamber 2, the receiving chamber 1 fills with liquid. In Fig. 11 the process has turned around again. The float 9 has closed the main valve 19 and opened the main valve 20. The non-return valve 31 and the negative pressure flap 6 have closed. From the open vacuum flap 5 liquid flows through the drain 7 from the receiving chamber 1 from. In the receiving chamber 2 32 liquid is sucked into the receiving chamber 2 via the suction port 30 and the open check valve.

The Fig. 13 and 14 show another embodiment of the embodiment with two vacuum flaps 5, 6. Instead, as shown, preferably a common negative pressure flap 56 are provided, which alternately closes the receiving chambers 1 and 2. The receiving chambers 1 and 2 terminate at the bottom in each outlet spout 45, 46, which forms stops 55 and 66 for the vacuum flap 56 at its peripheral edges. The vacuum flap is pivotally mounted between these stops 55 and 66. It may preferably be formed integrally from a single elastomeric element, wherein the pivot axis is formed as shown by a region 57 of reduced thickness. In Fig. 13 the negative pressure flap 56 closes the receiving chamber 2, thereby releasing the receiving chamber 1 towards the outlet 7, so that liquid can flow out there. If, however, a negative pressure is applied to the receiving chamber 1, then the negative pressure flap 56 pivots into the in Fig. 14 shown position, wherein it closes the receiving chamber 1 and at the same time the receiving chamber 2 to drain the liquid collected there through the drain 7 releases. Support it the weight of the liquid collected in the receiving chamber 2 and the negative pressure applied in the receiving chamber 1 mutually, so that the pivoting of the vacuum flap 56 for opening-closing change is very fast. Also, in contrast to the embodiment of the Fig. 2 to 11 in case of delayed movement of the flaps 5, 6 no mutual interference occur.

The illustrated embodiments of Fig. 2 to 14 are extremely low maintenance, mechanically simple and functionally reliable with continuously high suction power operable.

Fig. 15 shows a modified embodiment with also only one suction motor 3. The control, from which receiving chamber 1, 2 straight air is sucked, is in the embodiment according to Fig. 12 realized by a lever linkage with two switching levers 35, 36 which pivot a change-over flap 37, whereby the suction side of the suction motor 3 is alternately connected to the receiving chambers 1, 2. The main valves are formed by the switching flap 37.

The FIGS. 16 and 17 show yet another embodiment of a single-motor liquid aspirator according to the invention, in which the control, which receiving chamber 1, 2 is being filled, is formed by the container itself. For this purpose, the receptacle 13 is pivotally mounted and preferably as shown oscillating around a substantially horizontal axis 38. Each receiving chamber 1, 2 of the receptacle 13 in turn has an air intake opening 17, 18, wherein the pivoting of the receptacle 13 alternately one of the air intake openings 17, 18 is connected to the suction side of the suction motor 3 or separated from it. A seal of the air intake openings 17, 18 is then simplified if they have the same distance from the pivot axis or pendulum axis 38, in particular, if the local wall region of the receptacle 13 is formed bent circular segment. In this case, the air intake openings 17, 18 together with the wall of the receptacle 13 also form main valves as in the embodiment of the preceding figures. The mechanical connection or coupling of the main valves is in the embodiment of FIGS. 16 and 17 given by the rigid shape of the container 13 itself.

The pivoting of the receptacle 13 may be motorized, in particular time-controlled. Preferably, however, the receptacle 13 is subdivided into receiving chambers 1, 2, that adjusts a focus shift with increasing filling of a receiving chamber 1, 2 with liquid with simultaneous drainage of liquid from the other receiving chamber 2, 1. As a result, the receptacle 13 is automatically pivoted to a position which releases the other receiving chamber 2, 1 for filling, while a receiving chamber 1, 2 emptied. Such a division is given in a preferred, simple manner in that the receiving container 13 as shown has substantially the shape of a horizontal cylinder or a ball and is divided by a partition 40 into two receiving chambers 1, 2 having a substantially semicircular cross-section. Preferably, the air intake openings 17, 18 adjacent to be arranged on both sides of the partition wall 40 and the drain openings in the form of vacuum flaps 5.6 also on both sides of the partition 40 at the opposite end. In Fig. 16 the air suction opening 17 is connected to the suction side of the suction motor 3, whereby liquid is sucked into the receiving chamber 1 via a suction port, not shown. At the same time, the other air intake opening 18 of the other receiving chamber 2 with the pressure side of the suction motor 3 or with connected to the ambient air, so that under the weight of the liquid contained in the receiving chamber 2, the negative pressure flap 6 opens and the liquid can flow out of the receiving chamber 2. Due to the increasing filling of the receiving chamber 1 and the emptying of the receiving chamber 2 is a shift in emphasis in the receptacle 13, so that this about the pivot axis 38 of Fig. 16 to Fig. 17 pivoted automatically counterclockwise, causing in Fig. 17 Liquid is sucked into the receiving chamber 2 and the liquid can flow out of the receiving chamber 1.

All embodiments of the invention are characterized by the possibility of a continuous liquid suction operation, which doubles the suction speed compared to conventional liquid aspirators with the same engine power. The liquid aspirators according to the invention are preferably suitable as sludge suckers for the purification of garden ponds. You can, however, e.g. also be used for the carriage of other liquids, even if they contain many solids and / or have a higher viscosity, for example, building materials, such as screed materials, plasters or the like.

Claims (29)

1. Liquid aspirator, in particular for handling solids-containing liquids such as sludge, having a receiving container (13) into which liquid can be sucked by means of a suction motor (3, 4) through a suction connection (15) and from which the liquid is able to drain out through an outlet (7), characterized in that the receiving container (13) has at least two separate receiving chambers (1, 2), which can be sealed off from the suction end of the suction motor (3, 4) by means of valves or main valves (19, 20), and a control system by means of which, alternately, filling of one receiving chamber (1, 2) with liquid takes place while another receiving chamber (2, 1) is emptying.
2. Liquid aspirator according to claim 1, characterized in that each receiving chamber (1, 2) has a suction motor (3, 4) associated with it, and the control system switches the suction motors (3, 4) on and off alternately.
3. Liquid aspirator according to claim 1, characterized in that a suction motor (3) is designed to suck liquid alternately into a plurality of receiving chambers (1, 2), under the prompting of the control system.
4. Liquid aspirator according to one of the foregoing claims, characterized by a mechanical control system.
5. Liquid aspirator according to one of the foregoing claims, characterized in that the main valves (19, 20) are coupled together in such a way that they open and close alternately.
6. Liquid aspirator according to claim 5, characterized in that the main valves (19, 20) are connected together mechanically.
7. Liquid aspirator according to one of claims 4 to 6, characterized in that the main valves (19, 20) are coupled by means of a lever linkage.
8. Liquid aspirator according to claim 7, characterized in that the lever linkage pivots a changeover flap (37) which connects the suction end of the suction motor (3) alternately to one of the receiving chambers (1, 2) at a time.
9. Liquid aspirator according to claim 8, characterized in that the changeover flap (37) forms the main valves.
10. Liquid aspirator according to one of the foregoing claims, characterized in that a float (9, 10) is held in a guide (11, 12) in each receiving chamber (1, 2).
11. Liquid aspirator according to one of claims 5 to 8 and claim 9, characterized in that the float (9, 10) is so arranged below the given main valve (19, 20) that a rise in the liquid above a fixed level in the receiving chamber (1, 2) presses the float (9, 10) against the main valve (19, 20) and closes the latter.
12. Liquid aspirator according to one of claims 9 to 11, characterized in that the guide (11, 12) for the float (9, 10) is formed to be pierced in the bottom region and to be continuous in the circumferential direction in the top region (11', 12') and surrounds the float (9, 10) there, when the latter is in the raised position, with a seal formed.
13. Liquid aspirator according to one of the foregoing claims, characterized in that the receiving chambers (1, 2) are connected to the exhaust ends of their suction motors (3, 4), in such a way as to be able to be sealed off, by means of respective ancillary valves (23, 24).
14. Liquid aspirator according to one of claims 10 to 12 and claim 13, characterized in that the connecting of the exhaust ends of the suction motors (3, 4) to the receiving chambers (1, 2) is performed by the guides (11, 12) for the floats (9, 10).
15. Liquid aspirator according to claim 14, characterized in that respective connecting passages (42) extend to the adjacent floats (9, 10) from those sides of the ancillary valves (23, 24) which are remote from the exhaust ends of the suction motors (3, 4).
16. Liquid aspirator according to one of claims 13 to 15, characterized in that the main valve (19, 20) and ancillary valve (23, 24) of each receiving chamber (1, 2) are coupled in such a way that they open and close alternately.
17. Liquid aspirator according to one of claims 6 to 16, characterized in that the coupling of the valves (19, 20, 23, 24) is of a mechanical form.
18. Liquid aspirator according to claim 17, characterized in that the main valves (19, 20) are coupled by a rocker (21).
19. Liquid aspirator according to claim 17 or 18, characterized in that the ancillary valves (23, 24) are coupled by a rocker (25).
20. Liquid aspirator according to claims 18 and 19, characterized in that the rockers (21, 25) of the main valves (19, 20) and ancillary valves (23, 24) are connected together rigidly.
21. Liquid aspirator according to one of the foregoing claims, characterized in that the receiving chambers (1, 2) are of substantially cylindrical forms and/or are of substantially the same volumes and/or are arranged within one another.
22. Liquid aspirator according to one of the foregoing claims, characterized in that the receiving chambers (1, 2) can be closed off at the bottom end by a common flap valve (56) operated by a pressure below atmospheric which is mounted between two abutment points (55, 66) to be pivotable in such a way that it closes off one receiving chamber (1, 2) at a time and opens the other receiving chamber (2, 1) to the outlet by bearing against one of the stops (55, 66).
23. Liquid aspirator according to one of the foregoing claims, characterized in that the receiving container (13) is mounted to be pivotable.
24. Liquid aspirator according to claim 23, characterized in that the receiving container (13) is mounted to swing on a substantially horizontal axis (26).
25. Liquid aspirator according to claim 23 or 24, characterized in that each receiving chamber (1, 2) of the receiving container (13) has an air induction opening (17, 18) which is connected alternately to the suction end of the suction motor (3) by the pivoting of the receiving container (13).
26. Liquid aspirator according to claim 25, characterized in that the air induction openings (17, 18) are arranged in a wall region of the receiving container (13) which is formed to be curved at a substantially constant radius around the axis of pivot of the receiving container (13).
27. Liquid aspirator according to one of claims 23 to 26, characterized in that the receiving container (13) is divided into receiving chambers (1, 2) in such a way that, as a receiving chamber (1, 2) becomes increasingly filled with liquid, a displacement of the centre of gravity takes place by which the receiving container (13) pivots automatically to a position in which a different receiving chamber (2, 1) is opened for filling.
28. Liquid aspirator according to one of the foregoing claims not including claim 21, characterized in that the receiving container (13) is of a substantially circular shape in cross-section which is divided by a partition (40) into two receiving chambers (1, 2) of substantially semi-circular cross-section.
29. Liquid aspirator according to claim 25 and claim 28, characterized in that the air induction openings (17, 18) are arranged on the two sides of the partition (40) adjacent thereto and respective outlet openings which can be closed off are arranged in an opposite position on the two sides of the partition (40).

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