EP3427629B1 - Dishwasher, especially domestic dishwasher - Google Patents

Description

The invention relates to a dishwasher, in particular in the embodiment of a household dishwasher, with a washing compartment which provides a washing compartment and serves to hold items to be cleaned, a spray arm which is rotatably arranged within the washing container for applying washing liquor to the dishes, a collecting pan into which the washing container is placed flows in terms of flow technology and a sieve device that can be inserted into the collecting pot.

Dishwashers of the type mentioned at the outset are well known per se from the prior art, which is why a separate documentary proof is not required at this point.

Dishwashers of the generic type have a washing container which provides a washing compartment. This wash cabinet is accessible by the user via a loading opening which can be closed in a fluid-tight manner by means of a pivotably mounted wash cabinet door. In the intended use, the washing container serves to hold items to be cleaned, which in the case of a domestic dishwasher can be, in particular, dishes, cutlery and / or the like.

The dishwasher has a spray device on the wash cabinet side for loading wash ware with wash liquor. This spray device generally provides rotatable spray arms, typically two or three such spray arms being provided. In the intended use, the washware to be cleaned is loaded with wash liquor by means of rotating spray arms. A circulation pump is provided for the purpose of supplying the spray arms with wash liquor, which is connected on the one hand to the collection pot and on the other hand to the spray arms in terms of flow technology.

In the intended use, the washing liquor dispensed by the spray device collects in the collecting pot into which the washing container flows out in terms of flow. In circulation mode, the circulation pump conveys itself in the collection pot collecting washing liquor to the spray arms of the spraying device, from where the washing liquor is then dispensed onto the wash ware to be cleaned.

In terms of fluid technology, the collecting pot, into which the washing container opens, is separated from the spray space provided by the washing container by a sieving device. The rinsing liquor circulated in the intended use by the circulating pump therefore only collects in the collecting pot after it has passed the sieving device inserted in the collecting pot. Food residues, dirt particles and / or similar contaminants are retained by the sieving device, so that a washing liquor cleaned to this extent by sieving is circulated. Such a sieve device typically comprises a coarse sieve, a fine sieve and a flat sieve.

The contaminants retained by the screening device must be removed manually by the user after a washing program has been completed and then disposed of. In addition, the pores of the screening device may become clogged over time, so that a manual cleaning of the screening device by the user is required. For this purpose, the sieve device must be removed from the collecting pot on the user side and cleaned, for example in a sink under running water. In order to facilitate such cleaning of the screening device, it is known from the prior art to design the screening device to be removable, which allows the individual screens of the screening device to be detached from one another for the purpose of simplified cleaning.

Although known screening devices have proven themselves in everyday practical use, there is a need for improvement, especially with a view to cleaning them in the event of contamination. Because the removal of the screening device from the collecting pot of the dishwasher, which may be very complex, is perceived by the user as disadvantageous. Thus, the screening device is not always easily accessible whether the spraying device provided on the washing area side, for example when a spray arm hinders user-side access to the screening device as a result of its end position assumed after the end of the last washing program. In this case, the spray arm must first be rotated by the user for unhindered access to the screening device. In addition, due to the design, the sieve device can only be reached uncomfortably by a user, since it is arranged in the collecting pot, that is to say in the region of the bottom part of the washing container.

The US 2015/0352472 A1 discloses a dishwasher with a collecting pot and a sieve device which can be inserted into the collecting pot and which, in the final assembled state, is penetrated by a standpipe which is used to supply washing liquor to the spray arm, the spray arm being detachably arranged on the end of the standpipe, by actuating a Locking element a common locking and unlocking of the spray arm and screen device can be effected.

The US 3323529 A and the US 5700329 A show a dishwasher with a collection pot and a sieve device inserted into the collection pot, which is penetrated by a standpipe, which is used to supply washing liquor to the spray arm. Starting from the above, the object of the invention is to further develop a dishwasher of the type mentioned at the outset, that simplified handling of the screening device is permitted, in particular for cleaning purposes.

To achieve this object, a dishwasher is proposed having the features of claim 1 of the invention.

The dishwasher according to the invention has a washing compartment which provides a washing compartment and is used to hold the items to be cleaned, a spray arm which is rotatably arranged within the washing container to apply washing liquor to the items to be washed, a collecting pot into which the washing container flows in terms of flow technology, and a sieving device which can be inserted into the collecting pot on.

In the intended use, the spray arm is connected in terms of flow to a standpipe on the device side, so that circulated washing liquor can reach the spray arm with the standpipe being connected in terms of flow. It is provided according to the invention that the spray arm is detachably arranged on the end of the standpipe. The spray arm can therefore be detached from the standpipe if necessary so that the spray arm can be removed from the standpipe.

In the final assembled state, the sieve device is clamped in a sandwich-like manner between the collecting pot, that is to say its bottom and the spray arm arranged at the end of the standpipe. In the case of removal by the user, the spray arm is to be detached from the standpipe, which means unhindered access and removal of the Screening device allowed.

The configuration according to the invention therefore makes it possible not only to remove the screening device, but also, if necessary, the spray arm. This allows not only cleaning the spray device, but also cleaning the spray arm. It is also advantageous from the design point of view that the spray arm can be easily reached by the user regardless of the position and can therefore be detached from the standpipe. As soon as this has been done, not only the spray arm can be easily removed by the user, but also the sieve device underneath in the installed state. The configuration according to the invention therefore also allows a screen device to be cleaned to be removed easily by the user.

The reinstallation of the screening device is also possible in a simple manner, since it is only to be introduced into the collecting pot in the intended manner. The spray arm is then to be placed on the end of the standpipe, the sieve device also being fixed in position by arranging the spray arm on the standpipe. Because in the final assembled state, the sieve device is clamped between the spray arm arranged at the end of the standpipe on the one hand and the bottom of the collecting pot on which the sieve device rests, on the other hand.

The sieve device proposed by the invention is rotationally symmetrical in accordance with a preferred embodiment. In particular, in the final assembled state, the sieve device is preferably penetrated centrally by the standpipe, which is used to supply the washing liquor to the spray arm. The screens of the screening device are therefore preferably formed around a common central axis. This central axis coincides with the device-side standpipe, which passes through the rotationally symmetrical sieve device in the center in the final assembled state. A rotationally symmetrical sieve device enables an evenly distributed flow of circulated washing liquor into the collecting pot, so that the sieve device is evenly contaminated in the event of contamination. The rotationally symmetrical arrangement also has the advantage that the clamping force acting on the screening device in the final assembled state is equally distributed over the screening device, so that a permanently secure positional positioning of the screening device is ensured. In particular, wash-down effects like this can be avoided with regard to the screens of previously known screening devices may possibly occur.

According to a further feature of the invention, a locking element, which can be designed, for example, as a union nut, is used for the releasable arrangement of the spray arm on the standpipe. The standpipe and the union nut preferably cooperate via a bayonet catch, which is why the union nut has a part of a bayonet catch designed to correspond to the configuration of the standpipe serving as an abutment for the spray arm.

The locking element, which is designed, in particular, as a union nut, serves as a central actuating element in order to release the spray arm from the standpipe as intended, with only one hand movement. The construction according to the invention thus allows the spray arm and sieve device to be removed and then cleaned in a simple manner after a single actuation of the locking element. The locking element serves as a means to secure the spray arm and sieve device in the same position. In particular, actuation of the locking element can effect a common locking and / or unlocking of the spray arm and sieve device.

When used as intended, the union nut interacts with the standpipe. For this purpose, the standpipe has a section on the union nut side which is the opposite of the bayonet fitting part of the union nut. In the assembled state, these two parts form the bayonet lock, which is designed to position the union nut securely on the standpipe.

It is preferably provided that the union nut has an edge channel open on the sieve device side. The screen device engages in this edge channel in the final assembled state. Not only is the sieve device clamped between the bottom of the collecting pot and spray arm in the direction of the central axis of the sieve device, it is also secured in a direction transverse to the central axis. Because the positive engagement of the screening device in the edge channel of the union nut fixes the screening device in relation to the union nut and thus also in relation to the stationary standpipe.

The clamping of the sieve device between the spray arm and the bottom of the collecting pot is preferably done with resilient deformation of the screening device. This resilient deformation of the sieve device ensures that the sieve device, when fully assembled, presses against the union nut fixed in position on the standpipe in the height direction of the central axis. The bayonet lock formed between the union nut and the standpipe is thus subjected to a force, which counteracts an unintentional loosening of the bayonet lock by, for example, vibrations.

The sieve device has a coarse sieve, a fine sieve and a flat sieve, which are designed to be removable from one another, and are preferably arranged concentrically in the final assembled state. This ensures that all sieves of the sieving device are aligned centrally with respect to the central axis of the sieving device. According to a further feature of the invention, it is provided that the coarse screen interacts with the union nut. For this purpose, the coarse screen is equipped with an edge on the union nut side, which in the final assembled state engages positively in the edge channel provided by the union nut. The marginal edge of the coarse sieve and the marginal channel of the union nut are matched to one another in their geometric dimensions in such a way that a relative movement transverse to the central axis of the sieving device is effectively prevented.

According to a further feature of the invention, the union nut and the coarse sieve have corresponding position markings. These serve to enable the user to visually check in a simple manner whether the union nut is properly aligned with respect to its coarse sieve relative to the coarse sieve, so that it is properly arranged on the standpipe, ie there is a properly secured arrangement of the spray arm. For this purpose, the union nut preferably has at least one through opening or a transparent section through which a position marking carried by the coarse sieve is visible, at least when properly aligned, in particular when the union nut is rotated relative to the coarse sieve. The position marker carried by the union nut can be formed by the through opening or the transparent section itself. When the union nut is properly aligned or rotated relative to the coarse sieve, the position marking carried by the coarse sieve is positioned centrally within the through opening or the transparent section provided by the union nut. Preferably, however, the coarse screen can additionally have a separate position marking around the center of the through opening or of the transparent section. This enables an even better comparison of the relative positioning of the union nut and coarse sieve. In this exemplary embodiment, there is no need to provide a position marking on the flat screen.

The invention further proposes a spray device for a dishwasher, in particular for a dishwasher of the type described above, with a spray arm rotatably arranged in the final assembled state and with a means for releasably arranging the spray arm on an abutment on the machine side.

The spray device according to the invention thus provides at least one spray arm which is designed to be both rotatable and detachable. For this purpose, a means is provided according to the invention that serves for the releasable arrangement of the spray arm on the associated abutment of the dishwasher. The detachable arrangement of the spray arm has the advantage of being able to remove the spray arm if necessary. Such removal is desired by the user, for example, in order to be able to clean the spray arm independently of the execution of a washing program. The detachable arrangement therefore allows a user to be able to detach the spray arm from the machine-side abutment if necessary and to remove it from the dishwasher. The spray arm can then be cleaned outside the dishwasher, for example in a sink under running water. After cleaning, the spray arm can be reinstalled in the dishwasher by being arranged as intended on the machine-side abutment.

A union nut is preferably used as the means for releasably arranging the spray arm on a machine-side abutment. This is preferably arranged so that it cannot be lost on the spray arm and has a connecting contour which corresponds to a counter-contour of the abutment. A bayonet catch is preferably used as the connecting contour, since this allows particularly simple handling for the assembly or disassembly of the spray arm by the user.

The invention also proposes a screening system for a Dishwasher, in particular for a dishwasher of the type described above, with a screening device which is at least partially accommodated in the final assembled state by a collecting pan of the dishwasher and a spray arm of a spray device which is detachably rotatably arranged on an abutment on the machine side in the final assembled state, the screening device being designed around a central axis, wherein the center axis of the screening device and the axis of rotation of the spray arm coincide.

The screening system proposed by the invention has a screening device on the one hand and a spray arm on the other. The spray arm is rotatably arranged, namely about an axis of rotation. The screening device in turn has a central axis, it being provided according to the invention that the central axis and the rotational axis coincide. When used as intended, the spray arm therefore rotates around the central axis of the screening device.

The configuration according to the invention produces a symmetrical arrangement, namely a rotationally symmetrical arrangement of the sieve device and spray arm. The spray arm is detachably arranged on an abutment of the dishwasher in the manner described above, so that after loosening the spray arm it is particularly easy on the user side due to the rotationally symmetrical design to be able to remove the spray arm together with the sieving device from the washing area of the dishwasher.

The sieve device has concentrically arranged sieves, which also simplifies the operation of the sieve device, particularly in the case of removal.

According to a further feature of the invention, the screens of the screening device are each circular in cross section. This also serves to simplify handling.

Overall, the construction described above allows the spray arm and the sieve device to be fixed in position by means of only one actuating or locking element, in particular the union nut, or to be able to release a positional fixation for removal. In contrast to the prior art, this results in a significantly improved and simplified handling.

Fig. 1

in rein schematischer Seitendarstellung eine Geschirrspülmaschine der erfindungsgemäßen Art;

Fig. 2

in schematisch perspektivischer Darstellung einen Spülbehälter der erfindungsgemäßen Geschirrspülmachine;

Fig. 3

in einer schematischen Detailansicht den unteren Sprüharm einer Sprüheinrichtung der erfindungsgemäßen Geschirrspülmaschine;

Fig. 4

in teilgeschnittener Seitenansicht die Sprüharmanordnung nach Figur 3;

Fig. 5

in schematisch perspektivischer Darstellung den unteren Sprüharm der erfindungsgemäßen Geschirrspülmaschine in einer ersten Stellung;

Fig. 6

in schematisch perspektivischer Darstellung den unteren Sprüharm der erfindungsgemäßen Geschirrspülmaschine in einer zweiten Stellung;

Fig. 7

in schematisch perspektivischer Darstellung ein demontierter unterer Sprüharm;

Fig. 8

in schematischer Perspektivdarstellung eine demontierte Siebeinrichtung;

Fig. 9

in einer Detailansicht den unteren Sprüharm nach Figur 7;

Fig. 10

in einer schematischen Detailansicht den unteren Sprüharm einer Sprüheinrichtung eines weiteren Ausführungsbeispiels der erfindungsgemäßen Geschirrspülmaschine bei unverschlossener Stellung der Überwurfmutter;

Fig. 11

in einer schematischen Detailansicht den unteren Sprüharm einer Sprüheinrichtung des Ausführungsbeispiels von Fig. 11 in verschlossener Stellung der Überwurfmutter und

Fig. 12

in einer schematischen Detailansicht die Siebeinrichtung von Fig. 10 und 11 bei abmontiertem Sprüharm.

Further features and advantages of the invention result from the following description with reference to the figures. Show

Fig. 1

in a purely schematic side view, a dishwasher of the type according to the invention;

Fig. 2

in a schematic perspective view of a washing container of the dishwasher according to the invention;

Fig. 3

in a schematic detailed view the lower spray arm of a spray device of the dishwasher according to the invention;

Fig. 4

in a partially sectioned side view of the spray arm arrangement Figure 3 ;

Fig. 5

in a schematic perspective view, the lower spray arm of the dishwasher according to the invention in a first position;

Fig. 6

in a schematic perspective view the lower spray arm of the dishwasher according to the invention in a second position;

Fig. 7

a disassembled lower spray arm in a schematic perspective representation;

Fig. 8

a disassembled screening device in a schematic perspective view;

Fig. 9

in a detailed view the lower spray arm Figure 7 ;

Fig. 10

in a schematic detailed view the lower spray arm of a spray device of a further embodiment of the dishwasher according to the invention with the union nut in the unlocked position;

Fig. 11

in a schematic detailed view of the lower spray arm of a spray device of the embodiment of Fig. 11 in the closed position of the union nut and

Fig. 12

in a schematic detailed view of the screening device of 10 and 11 with the spray arm removed.

Figure 1 can be seen in a purely schematic representation of a dishwasher 1 in the form of a program-controlled household dishwasher.

The dishwasher 1 has, in a manner known per se, a housing 2 which receives a washing container 3. The washing compartment 3 in turn provides a washing compartment 4 for receiving items to be cleaned. For loading the wash cabinet 4 with items to be cleaned, the wash container 3 has a loading opening 9. This loading opening 9 can be closed in a fluid-tight manner by means of a wash cabinet door 10, the wash cabinet door 10 being mounted so as to be pivotable about a horizontally extending pivot axis.

In the intended use, the washware to be cleaned is loaded with washing liquor, for which purpose the dishwasher 1 has a spray device 6. In the embodiment shown, the spray device 6 includes an upper spray arm 7 and a lower spray arm 8.

In terms of flow technology, the spray device 6 is connected to a circulation pump (not shown in the figures) of the dishwasher 1, by means of which the spray arms 7 and 8 of the spray device 6 are supplied with washing liquor.

The washing compartment 3 providing the washing compartment 4 opens out with reference to the drawing level Figure 1 on the underside in a collecting pot 5. The circulation pump, not shown in the figures, is connected to this collecting pot 5. In terms of fluid technology, the collection pot 5 is removed from the washing compartment 4 of the washing container 3 by an in Figure 1 Separating device 12, not shown in detail. The rinsing liquor circulated in the intended use by the circulating pump collects in the pot 5 after it has dripped from the items to be washed and after it has passed through the screening device 12. From there it reaches the spray arms 7 and 8 of the spray device 6 in the circulating mode in the manner already described.

The screening device 12 is, in particular, a synopsis of the Figures 2 and 8th reveals, rotationally symmetrical. The sieve device 12 has Via a flat screen 14, a coarse screen 15 and a fine screen 16, each of which are aligned coaxially with a common central axis 24.

For a fluidic connection of the lower spray arm 8 to the circulation circuit supplied by the circulation pump with rinsing liquor, a stationary standpipe 17 is used, to which the spray arm 8 is connected at the end in the final assembled state, as can be seen particularly from the illustration Figure 4 results.

According to the invention, it is provided that the standpipe 17, which is connected to the lower spray arm 8 in terms of flow in terms of flow technology, extends through the center of the sieve device 12. The center axis of the standpipe 17 and the center axis 24 of the screening device 12 therefore coincide. As a result, the axis of rotation about which the lower spray arm 8 rotates in the intended use and the central axis 24 of the screening device 12 also coincide. The lower spray arm 8 thus rotates about the central axis 24 of the screening device 12. According to the invention, it is further provided that the spray arm is detachably arranged on the end of the standpipe 17. This allows the spray arm 8 to be separated from the standpipe 17 when necessary and to be removed from the dishwasher 1. As soon as the spray arm 8 is detached from the standpipe 17, the sieving device 12 can be removed from the collecting pot 5 in a simple manner by lifting the sieving device 12 upwards out of the collecting pot 5 in the height direction of its central axis 24, as shown in the illustration Figure 8 reveals.

A union nut 13 is used for the releasable arrangement of the spray arm 8 on the standpipe 17. In the final assembled state, the union nut 13 is fixed in position relative to the standpipe 17. A bayonet lock is provided for this purpose, with corresponding cams 18 being provided by an upper section 22 of the standpipe 17. A shoulder 19 of the union nut 13 provides a corresponding counter contour on the inside, ie facing the standpipe 17, which engage in one another in the final assembled state, as shown in the illustration Figure 4 reveals.

The union nut 13 also has a cylindrical section in the form of a tubular extension 23 which, in the final assembled state, bears against the outer tube 17 on the outer circumferential surface. In this way, a tilt-proof arrangement of the union nut 13 on the standpipe 17 is achieved.

How Figure 4 Furthermore, it can be seen that the union nut has a peripheral edge channel 21 on the sieve device side. In the final assembled state, an edge edge 20 of the coarse sieve 15 of the sieve device 12 provided in a form-fitting manner on the union nut side engages. This form-fitting engagement ensures that the screen device 12 is fixed securely in position in the final assembled state by means of the union nut 13, so that a relative movement of the screen device 12 to the standpipe 17 is also prevented in a direction running transverse to the central axis 24.

As can be seen from the above design description, the screen device 12 is clamped in the final assembled state between the bottom of the collecting pot 15 and the union nut 13 fixed relative to the standpipe 17. By loosening this union nut 13, the connection between union nut and standpipe 17 is released, which on the one hand makes it possible to remove the spray arm 8 and the sieve device 12 from the wash cabinet 4. This makes it possible to unlock and lock the screen device 12 and spray arm 8 with only a single control element. This simplifies the unlocking and locking process on the user side and also makes it easier to be able to remove the sieving device 12 and the spray arm 8 of the dishwasher for the purpose of, for example, manual cleaning.

How, for example Figure 8 furthermore results, the collection pot 15 is aligned centrally to the bottom part 11 of the washing compartment 3. There is therefore a rotationally symmetrical alignment of the collecting pot, standpipe 17, sieving device 12 and spray arm 8, the rotational symmetry about the central axis 24 being obtained.

10 and 11 show a schematic detailed view of the lower spray arm 8 of a spray device of a further embodiment of the dishwasher according to the invention. The design and arrangement of the standpipe 17, the coarse screen 15 and the union nut 13 largely corresponds to the above-described designs, in particular the description of the Figures 4 , 7 , 8th and 9 . Therefore, only the existing differences of the further exemplary embodiment are shown below. In this case, the union nut 13 and the coarse screen 15 have position markings 34, 35 which correspond to one another. These serve to make it easy for the user to visually check whether the Union nut 13 is properly aligned relative to the coarse sieve 15 with respect to its angle of rotation, it is thus properly arranged on the standpipe 17, that is to say there is a properly secured arrangement of the spray arm 8. The union nut 13 has a through opening 36 through which a position marker 35 carried by the coarse sieve 15 is visible, at least when the union nut is rotated relative to the coarse sieve 15 to such an extent that its closed position, ie its correct orientation and thus that for the operation of the Dishwasher proper alignment of the spray arm 8 is reached. Fig. 10 shows the still unlocked position while Fig. 11 shows the closed position. The latter shows the position marker 35 provided by the coarse screen 15, which is not covered due to the passage opening 36. The position marker 35 is designed as an inwardly directed web, starting from the edge 20 of the coarse screen 15, which can be approximately triangular or tapered inwards. In contrast, the union nut 13 provides a position marker 34, here in the form of a symbol, for example a stylized door lock, which is intended to signal the closed position to the user. If the position marker 35, in particular the tip of the web, points exactly to the symbol of the position marker 34, the user recognizes the presence of the closed position in a simple and intuitive manner. In a simplified version of this exemplary embodiment, it is also possible for the through opening 36 itself to be used as a position marking provided by the union nut, that is to say the symbol shown here is also dispensed with. In this case, a closed position would be achieved if the position marker 35, ie the tip of the web, is positioned centrally within the passage opening 36.

Fig. 12 shows a schematic detailed view of the screening device 12 of FIG 10 and 11 , with the spray arm and union nut removed. This gives a perspective view of the standpipe 17 and the sieve device 12, in particular the coarse sieve 15 and its peripheral edge 20 closing at the top. This serves, as in connection with FIG Fig. 4 shown, for positive engagement in an edge channel 21 provided by the union nut 13. Position marks 35 are formed on the edge at three locations, each in the form of an inwardly directed web starting from the edge 20 of the coarse screen 15. <b> reference number </b> 1 dishwasher 18th cam 2nd casing 19th shoulder 3rd Rinsing tank 20th Edge 4th Washroom 21st Marginal canal 5 Collection pot 22 section 6 Spraying device 23 Pipe extension 7 upper spray arm 24th Central axis 8th lower spray arm 34 Position marker 9 Loading opening 35 Position marker 10th Washroom door 36 Through opening 11 Bottom part 12 Screening device 13 Cap nut 14 Flat screen 15 Coarse sieve 16 Fine sieve 17th Standpipe

Claims (4)

1. Dishwasher, in particular a domestic dishwasher, comprising a washing container (3) which provides a washing compartment (4) and is used to accommodate washware to be cleaned, comprising a spray arm (8) which can be rotated within the washing container (3) in order to apply washing solution to the washware, comprising a collecting pot (5) into which the washing container (3) fluidically leads, and comprising a screening device (12) which can be inserted into the collecting pot (5) and through which, in the final assembled state, a standpipe (17) passes which is used to supply washing solution to the spray arm (8), the spray arm (8) being detachably arranged at the end of the standpipe (17),
   and comprising a locking element (13) for detachably arranging the spray arm (8) on the standpipe (17), it being possible for the spray arm (8) and the screening device (12) to be commonly locked and/or unlocked by actuating the locking element (13),
   and the screening device (12) having a coarse screen (15) which interacts with the locking element,
   characterised in that
   the locking element and the coarse screen (15) bear corresponding position markings (34, 35).
2. Dishwasher according to claim 1, characterised in that the locking element is designed as a cap nut (13), the cap nut (13) comprising a part of a bayonet fastener that is designed to correspond to the design of the standpipe (17) which is used as an abutment for the spray arm (8).
3. Dishwasher according to claim 2, characterised in that the cap nut (13) has a screening device-side open edge channel (21) into which the screen arrangement (12) engages in the final assembled state.
4. Dishwasher according to any of the preceding claims, characterised in that the screening device (12) has a coarse screen (15), a fine screen (16) and a planar screen (14) which are demountable from one another and are preferably arranged concentrically in the final assembled state.

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