Open-end spinning device with an intermediate chamber

An open-end spinning device of a rotor spinning machine has a spinning rotor with a rotor cup, in which fiber material is spun, and with a rotor shaft through which the spinning rotor is driven. A bearing is arranged in a contactless way with a drive to drive the spinning rotor. A rotor housing is provided in which the rotor cup is arranged and which is impinged with spinning negative pressure (pSU) during spinning operation through a negative pressure channel. A drive housing is provided in which the rotor shaft of the spinning rotor extends, and in which the drive and the bearing of the spinning rotor are arranged. The rotor housing and the drive housing are arranged spaced apart from one another in the open-end spinning device in the axial direction of the rotor shaft. In a method to operate such an open-end spinning device, the rotor housing is impinged with spinning negative pressure (pSU) during the spinning operation. Air current is prevented from flowing from the rotor housing into the drive housing by arranging the rotor housing and the drive housing spaced apart from one another in the axial direction of the rotor shaft.

FIELD OF THE INVENTION

The present invention refers to an open-end spinning device of a rotor spinning machine with a spinning rotor that has a rotor cup, in which fiber material can be spun, and a rotor shaft through which the spinning rotor can be driven, arranged in a preferably contactless bearing. Furthermore, the open-end spinning device has a drive for running the spinning rotor and a rotor housing, in which the rotor cup of the spinning rotor is arranged, impinged with spinning negative pressure during the spinning operation via a negative pressure channel of the spinning position. In addition, the open-end spinning device has a drive housing in which the rotor shaft of the spinning rotor extends and in which the drive and the bearing of the spinning rotor are arranged.

BACKGROUND

Among bearings for open-end spinning rotors, apart from the bearing in a supporting disk wedge slit, contactless bearings such as magnetic bearings and air bearings have also become known. Usually, rotors mounted in this way are electric motor driven by an individual drive. The rotor housing, which is under negative pressure during operation, is closed with a detachable lid to allow access to the rotor housing under certain situations. For example, if spinning is interrupted because a thread break or a cleaning step requires the opening of the rotor housing to perform maintenance work. Sometimes operating staff must open the rotor housing during continuous operation as well. On the other hand, the bearing and drive are arranged in a drive housing largely separated from the rotor housing, first of all to keep the volume of the rotor housing to be impinged with negative pressure small, and secondly to protect the drive and bearing of the spinning rotor from dirt (i.e. dust and fiber fly). Owing to the very high revolutions per minute of the rotating spinning rotor, it is not possible to seal the rotor housing to the drive housing completely, so that a negative pressure starts building up inside the drive housing too during the spinning operation. For example, EP 1 156 142 B1 shows an open-end spinning device with such an individually driven and magnetically mounted spinning rotor.

If the rotor housing under negative pressure of such an open-end spinning device is now opened, pressure compensation occurs, while negative pressure still prevails in the contiguous drive housing. Because of this, dirt that had accumulated in the rotor housing can now be sucked into the drive housing when the rotor housing is opened. If this dirt now reaches all the way to the individual drive of the spinning rotor and to the bearing, it can cause the failure of the bearing and drive.

EP 2 069 562 A1 therefore suggests to provide the drive housing with an additional air inlet and to supply compressed air to the drive housing before the rotor housing is opened so pressure compensation can take place there even before the rotor housing is opened. As a result of this, no dirt is sucked into when the rotor housing is opened.

SUMMARY OF THE INVENTION

A task of the present invention is to suggest an open-end spinning device in which dirt is prevented from being sucked into the drive housing, at least when the rotor housing is opened, and that can be used with different bearing types. Additional objects and advantages of the invention will be set forth in part in the following description, or may be obvious from the description, or may be learned through practice of the invention.

The objects are solved by the characteristics of the spinning device described and claimed herein.

An open-end spinning device of a rotor spinning machine has a spinning rotor with a rotor cup, in which fiber material can be spun, and a rotor shaft through which the spinning rotor can be driven, mounted on a preferably contactless bearing. Furthermore, the open-end spinning device has a drive, especially an individual drive, to drive the spinning rotor, a rotor housing, in which the rotor cup of the spinning rotor is arranged (impinged with spinning negative pressure during the spinning operation through a negative pressure channel of the spinning position), as well as a drive housing in which the rotor shaft of the spinning rotor extends and in which the drive and the bearing of the spinning rotor are arranged. The invention foresees the rotor housing and the drive housing arranged in the open-end spinning device spaced apart in the axial direction of the rotor shaft.

As part of the present invention, the rotor housing and the drive housing are understood to be merely the housing immediately surrounding the rotor or drive—formed in each case by a front and back delimiting wall and either a circumferential side wall (in the case of a cylindrical housing, for example) or several individual side walls. Here, the front delimiting wall faces the draw-off side of the spinning device and in the case of the rotor housing it is formed by a detachable lid in which the draw-off nozzle is generally arranged as well. The back delimiting wall, on the other hand, faces the drive side of the spinning device. Thus, for example, the rotor housing and/or the drive housing can also be connected to one another via a spacer that ensures the separated arrangement of the rotor housing and drive housing. Such a spacer can also be formed as one part on the rotor housing and/or drive housing.

In a method for operating an open-end spinning device of a rotor spinning machine, in which the open-end spinning device is driven by a drive, especially an individual drive arranged in a bearing, preferably contact-less arranged spinning rotor with a rotor cup and rotor shaft, and in which the rotor cup of the spinning rotor is arranged in a rotor housing, the rotor housing is impinged with spinning negative pressure during the spinning operation. Here, the rotor shaft of the spinning rotor extends in a drive housing, in which furthermore the drive and bearing of the spinning rotor are also arranged. The method prevents an air current from the rotor housing to the drive housing by arranging the rotor housing and the drive housing at equal distances from one another in an axial direction of the rotor shaft in the open-spinning device.

Owing to the spaced-apart arrangement of the rotor housing and the drive housing, surrounding air pressure prevails both during the spinning operation and when the rotor housing is opened in the area contiguous to the rotor housing and the drive housing that is not sealed to the exterior surroundings. Thus, no negative pressure can build up in the drive housing during the spinning operation. Therefore, when the rotor housing is opened and pressure compensation takes place in it, dirt particles can no longer be sucked into the drive housing.

According to an advantageous further development of the invention, an intermediate chamber has been arranged between the rotor housing and the drive housing, and this intermediate chamber has a first connecting opening to the rotor housing and a second connecting opening to the drive housing. Moreover, the intermediate chamber has a third opening through which the intermediate chamber is connected either to a negative pressure source or to surrounding air pressure, at least when the spinning operation is interrupted.

In the method used to operate the open-end spinning device, an intermediate chamber has been arranged between the rotor housing and the drive housing, connected to the rotor housing through a first connecting opening and to the drive housing through a second connecting opening. Here, the shaft of the spinning rotor extends from the rotor housing to the drive housing. The method provides the intermediate chamber to be impinged (at least when the spinning operation is interrupted) in such a way with negative pressure or surrounding air pressure that when the rotor housing is opened, an air current is at least prevented from flowing into the drive housing. Preferably, an air current from the drive housing to the intermediate chamber is generated in the method.

Thus, the intermediate chamber is impinged at least simultaneously with negative pressure or surrounding air pressure as soon as the rotor housing starts to be opened, but preferably already shortly before that. While this occurs, the intermediate chamber remains at least impinged as long as the interruption of the spinning process lasts or as long as the rotor housing is opened. However, it is also possible to impinge the intermediate chamber constantly, i.e. during the spinning operation as well. Therefore, the arrangement of the intermediate chamber between the rotor housing and the drive housing makes it possible to prevent, or at least largely prevent, an air current of dirty air to be sucked into the drive housing by the selective impingement of the intermediate chamber. In particular, the impingement of the intermediate chamber with negative pressure can also generate a selective air current through the intermediate chamber that not only counteracts a sucking in of dirt particles into the drive housing when the rotor housing is opened, but can also prevent deposits during the operation.

Here, the intermediate chamber can be executed as a separate housing or as extension of the rotor housing or drive housing or of both. For example, the side wall(s) of the rotor housing can be extended beyond its back delimiting wall and form the intermediate chamber as a result of that. The intermediate chamber formed in this way is sealed from the adjoining drive housing by means of a seal. Analogously, the side wall(s) of the drive housing could also be extended beyond its front delimitation wall.

Here, the first and/or second connecting opening is/are preferably arranged around the rotor shaft. In particular, the first and/or second connecting opening is/are executed as ring gap around the rotor shaft, as it is not possible to fully seal the housings against one another most of the time. However, it is also possible to place the connecting openings, especially the first connecting opening to the rotor housing, in the area of a collar of a rotor cup. The first connecting opening, in particular, can therefore also be executed as ring gap around the rotor disk collar. It is thus possible, on the one hand, to achieve a certain sealing of the housings or intermediate chamber to one another (which especially allows maintaining the spinning negative pressures in the rotor housing) and nonetheless create a selective air current through the ring gaps that transports dirt away. If the first connecting opening is provided in the area of the rotor cup collar, then it is possible—at least in one intermediate chamber impinged with negative pressure—to advantageously suck possible dirt out of the coupling location between rotor shaft and rotor cup when the latter is disassembled.

It is furthermore advantageous if the bearing comprises an axial bearing facing away from the rotor cup that acts on the end of the spinning rotor. This takes over the axial bearing of the spinning rotor, so that the radial bearing of the spinning rotor can be executed independently of it. As a result of this, the execution and control of the radial bearing are simplified and the bearing is less vulnerable compared to an execution in which no separate axial bearing is provided.

It is especially advantageous if the axial bearing is executed as axial air bearing or comprises at least an axial air bearing, because this design can support the creation of an air current from the drive housing into the intermediate chamber. However, the invention can also be used in an open-end spinning device in which the axial bearing of the spinning rotor is also executed as a magnetic bearing or in another way too.

It is additionally advantageous if the bearing comprises a magnetic bearing, especially a radial magnetic bearing. Especially in an individually driven spinning rotor, the execution of the radial bearing of the open-end spinning rotor as a magnetic bearing is advantageous. Since such magnetic bearings are very prone to become dirty, the advantageous design that includes a selective air current with the help of an intermediate chamber between the rotor housing and the drive housing is very effective there.

According to an advantageous first embodiment of the invention, the intermediate chamber is impinged with negative pressure, at least when the rotor housing is opened, preferably even before the rotor housing is opened. To achieve this, the intermediate chamber has—apart from the two connecting openings executed as a ring gap—a third opening connected to a negative pressure source. When the rotor housing is now opened, there is pressure equalization with the surroundings in the rotor housing, and then as a result of the negative pressure prevailing in the intermediate chamber and ring gap area between the intermediate chamber and the drive housing, dirt is prevented from being sucked into the drive housing. The special advantage of this design is that there is also negative pressure in the area of the connecting opening from the intermediate chamber to the rotor housing, so that any deposits from the area behind the rotor cup can be sucked out and immediately transported away. If at least the axial bearing of the spinning rotor, possibly also the radial bearing, is executed here as an air bearing, then the air current through the intermediate chamber can be furthermore supported as a result of this.

It is very advantageous here if the intermediate chamber is constantly impinged with negative pressure, also during the spinning operation, because this makes it possible to prevent the deposit and movement of impurities already during the spinning operation.

In an extremely advantageous embodiment, both the intermediate chamber and the rotor housing are impinged with spinning negative pressure. To achieve this, the intermediate chamber is directly connected to the negative pressure channel of the open-end spinning device via the third opening for the spinning negative pressure. Thus, with the exception of providing an intermediate chamber, no more constructive measures need to be implemented, thus allowing the open-end spinning device to be made economically too. In this case, the intermediate chamber can be connected to the negative pressure channel, which also connects the rotor housing with the negative pressure source or a machine-long negative pressure line, or they can have their own negative pressure channel to the negative pressure source or to the machine-long negative pressure line. Another advantage of this embodiment is that an air current from the intermediate chamber to the negative pressure channel is generated at least when the rotor housing is opened, and the current ensures not only that air is prevented from being sucked into the drive housing but also that air is actively transported away from the drive housing.

However, according to a variation of this embodiment, it is not necessary to impinge the intermediate chamber with negative pressure all the time. Rather, it is sufficient to do this just before or also only until the rotor housing is opened. In this case, the third opening of the intermediate chamber can be provided with a controllable shut-off device that can be activated preferably by the opening and closing of the rotor housing. Thus, for example, the opening of the rotor housing or of a swivel housing linked to the rotor housing can be registered by a sensor, which in turn triggers the activation of the shut-off device. Needless to say, a purely mechanical coupling of the shut-off device with the rotor housing is also possible.

On the other hand, according to another embodiment, the third opening is not connected to a negative pressure source but merely connected to the surrounding air. Here, the intermediate chamber is constantly impinged with surrounding air pressure via the third opening or is connected to the surrounding pressure. In this case, the forming of a negative pressure in the drive housing during the spinning operation is prevented due to the surrounding air pressure in the intermediate chamber. Therefore, when the rotor housing is opened too, no air is sucked into the drive housing. This embodiment can also be used both with a magnet bearing and with an air bearing or with a combined bearing. In this context, it is also possible to supply only small air doses through the third opening of the intermediate chamber that are just enough to prevent dust from being sucked in from the rotor housing into the intermediate chamber or drive housing. Furthermore, as a result of this, a very small amount of air can be supplied to the rotor housing to prevent from the outset deposits in the rotor housing behind the rotor disk. Thus, no impurities can reach the drive housing any longer even if the rotor housing is opened because of the pressure increase occurring there. Here, the amount of the supplied air can be regulated through the size of the third opening. In this case, a pressure occurs in the intermediate chamber and (owing to the connecting opening to the drive housing) in the drive housing also, which although being higher than the spinning negative pressure in the rotor housing, is still below the surrounding air pressure (due to the small amount of air supplied).

It is furthermore advantageous if the surrounding air is filtered before supplying it to the intermediate chamber. For this purpose, the third opening is preferably provided with an air filter in an open-end spinning device. Filtering the air being supplied to the intermediate chamber can therefore prevent dirt from penetrating the rotor housing from the surroundings.

If the bearing of the spinning rotor has an air bearing, then it is advantageous for implementing the method if the air throughput is controlled by the air bearing in such a way that a larger pressure will always prevail in the drive housing than in the intermediate chamber. As a result of this, air and dirt can be prevented not only from being sucked into an intermediate chamber impinged with negative pressure or surrounding air pressure when the rotor housing is opened, but at the same time impurities are prevented from penetrating the drive housing during the spinning operation. Such impurities can also form during normal spinning operation without dirty air being actively sucked in owing to the insufficient sealing of the ring gap area.

DETAILED DESCRIPTION

FIG. 1shows a schematic side view of an open-end spinning device1of a rotor spinning machine2. The rotor spinning machine2usually comprises a feeding device8, which supplies fiber material6to the open-end spinning device1through an opening device9that opens the fiber material into individual fibers. In the open-end spinning device1, the fiber material6is spun to yarn7in a rotor cup4(seeFIGS. 2-6) of a spinning rotor3, drawn off through a draw-off device10and wound on a bobbin12with a winding device11.

Apart from the spinning rotor3with the rotor cup4and rotor shaft5(seeFIGS. 2-6), the open-end spinning device1comprises a rotor housing15, in which the rotor cup4is arranged, and a drive housing17, in which the shaft5of the spinning rotor3extends. According to this description, the spinning rotor3is driven by means of an individual drive14and arranged in a bearing13. Here, support disk bearings, magnetic bearings and air bearings are considered as a bearing13of the spinning rotor. In this case, the bearing13comprises radial bearings25and can additionally also comprise an axial bearing24executed separately from the radial bearings25. The axial bearing24can be executed as an axial air bearing24aor as an axial magnetic bearing or also be formed by a combination of these two bearing types. Another type of bearing different from the bearing types shown can be used alternatively or additionally in the open-end spinning machines1ofFIGS. 2-6. For reasons of clarity, only the bearing13is labeled without its individual components here.

The rotor housing15is closed by means of a detachable lid27, especially one that can be swiveled (see arrow). To perform maintenance work on the open-end spinning device, the lid27of the rotor housing15can be removed either by an automatic maintenance mechanism or an operator, as symbolized here by an arrow. According to this drawing, the lid27of the rotor housing15is connected to a swivel housing29that can be swiveled out and opened together with it. However, it is also possible to provide the rotor housing15with a separate lid27. During the spinning operation, the rotor housing15is impinged with the spinning negative pressure pSUrequired for the spinning process by means of a negative pressure channel16of the open-end spinning device1. To do this, the negative pressure channel16of the open-end spinning device1is connected here to a machine-long negative pressure line33which, in turn, is connected to a central negative pressure source23. To maintain the spinning negative pressure pSUin the rotor housing15, a seal28has been placed between the lid27of the rotor housing15and the rotor housing15.

On the other hand, the drive14and the bearing13, which act together with the rotor shaft5of the spinning rotor3, are arranged in a drive housing17separated from the rotor housing15in order to protect it from impurities coming from the surroundings and also from fiber fly and impurities coming from the spinning rotor3area. Thus, the rotor shaft5of the spinning rotor3extends from the rotor housing15to the drive housing17.

Owing to the high revolutions per minute of the spinning rotor3, it is not possible to fully seal the rotor housing15from the drive housing17. In conventional spinning devices, this also leads to the build-up of negative pressure in the drive housing17as well during the spinning operation, which then in turn causes air and impurities to be sucked into the drive housing17from the rotor housing15area when the rotor housing15is opened. To prevent this, according toFIG. 1, the rotor housing15and the drive housing17are arranged spaced-apart from one another in the axial direction of the rotor shaft5in the open-end spinning device1. The drive housing17is now no longer directly connected to the rotor housing15but merely to an area of the open-end spinning device1not sealed from the surrounding air pressure pU. Thus, no negative pressure builds up in the drive housing17during the spinning operation, so that no impurities can be sucked any longer into the drive housing17even when the rotor housing15is opened. In this case, it is advantageous if the two housings15and17are separated from one another by at least 3 mm, preferably by at least 5 mm, very preferably by at least 10 mm, to securely prevent the effects that the negative pressure prevailing in the rotor housing15will have on the drive housing17. According to an advantageous further development, an intermediate chamber18is provided between the rotor housing15and the drive housing17arranged at a distance from it. Such an open-end spinning device1with the rotor housing15and the drive housing17will be described in more detail below with the help ofFIGS. 2-6, which show a detailed view of various embodiments of an open-end spinning device1.

FIG. 2shows once again the rotor3with the rotor cup4and the rotor shaft5. Furthermore, a draw-off nozzle34arranged in the lid27of the rotor housing15can be seen, through which the yarn7produced in the rotor cup4is drawn off. In the area of the drive housing17, both the individual drive14and the bearing13can now be recognized in detail. In this case, two radial bearings25executed as magnetic bearings25aare provided. Furthermore, an axial bearing24is provided that can comprise an axial magnetic bearing or an axial air bearing24aor an axial bearing24combined from both types of bearing. Here, an axial air bearing24afed by a pressurized air source31is shown that acts on an end of the spinning rotor3facing away from the rotor cup4.

Furthermore, it can be seen inFIG. 2that, in spite of the arrangement of ring seals21, a ring gap remains in each case between the contiguous housings or chambers. To prevent air of the rotor housing15area from being sucked into the drive housing17when the rotor housing15is opened, an intermediate chamber18has therefore been arranged between the rotor housing15and the drive housing17. The intermediate chamber18is connected to the rotor housing via a connecting opening19and to the drive housing17via a second connecting opening20. To keep the size of the connecting openings19and20as small as possible, a ring seal21is provided in each case in the area of the two ring gaps.

According to the embodiment of an open-end spinning device shown inFIG. 2, the intermediate chamber18has a third opening22that is in constant contact with a negative pressure source23. For example, the intermediate chamber18can be in contact with the negative pressure source23for the spinning negative pressure pSUthrough the machine-long negative pressure line33. Here, the intermediate chamber18is also connected to the negative pressure channel16for this.

Thus, during the spinning operation, spinning negative pressure pSUprevails in the rotor housing15, while a pressure PAG setsin inside the drive housing17owing to the axial bearing24executed as air bearing24athat exceeds the spinning negative pressure pSU. However, due to the very small amount of air passing through the air bearing24acompared to the amount of air passing through the negative pressure channel16, the air pressure PAGalways remains lower than the surrounding air pressure PUthat surrounds the spinning device1, even during the spinning operation. As a result of this, an air pressure PZKsets in inside the intermediate chamber18that is also lower than the surrounding air pressure PUand lies between the spinning negative pressure PSUand the air pressure of the drive housing PAG. Thus, during the spinning operation, an air current is generated from the drive housing to the intermediate chamber that advantageously prevents impurities from penetrating the drive housing17already during the spinning operation.

When the rotor housing15is opened, however, pressure is now equalized in the rotor housing15to that of the surrounding air pressure PU. Any impurities from the rotor housing15are now, however, merely sucked into the intermediate chamber18owing to the negative pressure PZKadjacent to the intermediate chamber and transported out to the negative pressure channel16through the third opening22. The penetration of impurities from the rotor housing15into the drive housing17can thus be prevented both during the spinning operation and when the rotor housing15is opened.

The effect described can be improved even more if, similarly toFIG. 3, the intermediate chamber18is connected to the machine-long negative pressure line33or another negative pressure source23via a separate negative pressure channel16a. Due to the sudden pressure compensation in the rotor housing15to the surrounding air pressure PUwhen the rotor housing15is opened, the pressure can also equalize in the negative pressure channel16, so that the intermediate chamber18can now no longer be sufficiently impinged with negative pressure. By connecting the intermediate chamber18by means of its own negative pressure channel16a, the negative pressure (air pressure PZK) in the intermediate chamber18can still be maintained after opening the rotor housing15. Alternately to an own negative pressure channel16afor the intermediate chamber18, it is also possible to arrange the third opening22or the connection of the intermediate chamber18to the negative pressure channel16near the machine-long negative pressure line33or connect the intermediate chamber18directly to the machine-long negative pressure line33. Owing to the spatial proximity to the machine-long negative pressure line33, sufficient negative pressure still prevails in this area even when the rotor housing15is opened.

SinceFIG. 3shows a variation of the open-end spinning device ofFIG. 2, only the differences to the device shown inFIG. 2will be discussed below; the same elements and modes of operation will no longer be described separately. According toFIG. 3, it is also foreseen for the intermediate chamber18to be connected to a negative pressure source23through a third opening22. For the pressure equalization reasons given inFIG. 2that also occur in the negative pressure channel16when the rotor housing15is opened, the intermediate chamber18is also connected here to the negative pressure source23through its own negative pressure channel16a. Naturally, and depending on the geometric conditions of the open-end spinning device1, the intermediate chamber18could be connected directly to the machine-long negative pressure line33. Compared to the open-end spinning device1ofFIG. 2, however, the third opening22has been provided with a controllable shut-off device26, so that the intermediate chamber18is not constantly in contact with the negative pressure source23but only until the lid27is opened. Due to the connecting openings19and20to the rotor housing15impinged with spinning negative pressure PSU, however, a negative pressure sets in also in the intermediate chamber18and in the drive housing17during the spinning operation. According to the present description, a sensor32is provided to achieve this, either in the area of the lid27of the rotor housings15or in the area of the swivel housing29to register the opening of the rotor housing15and the shut-off device26opens as a result of this. The intermediate chamber18is therefore further impinged with a negative pressure also when the lid27of the rotor housing15is opened, thus preventing impurities from being sucked into the drive housing17. Any deposits from the rotor housing15area are also transported away via the third opening22and the negative pressure channel16aafter the shut-off device26is opened.

Due to the fact that the intermediate chamber18is in any case impinged with spinning negative pressure PSUwhen the rotor housing15is opened, any impurities from the rotor housing15are sucked out through the negative pressure channel16aand no longer reach the drive housing17. The penetration of impurities into the drive housing17can therefore be prevented with all bearing types. However, this effect can be enhanced even more if—as in the description forFIG. 2—the axial bearing24is executed as axial air bearing24aor the bearing comprises an air bearing. In this case, a higher air pressure PAGwill always prevail in the drive housing17than the air pressure PZKin the intermediate chamber18. As a result of this, the sucking of impurities is once again prevented.

FIG. 4shows another variation of the open-end spinning device1shown inFIG. 2with an intermediate chamber18impinged with negative pressure, in which the intermediate chamber18is connected to the negative pressure channel16of the rotor housing15via the third opening22. To prevent the negative effect of pressure equalization in the negative pressure channel16described already underFIG. 2when the rotor housing15is opened, instead of providing a separate negative pressure channel16a, it can also be closed against the negative pressure channel16when the rotor housing15is opened. To do this, the rotor housing15is provided with a shut-off device26that blocks or allows its connection to the negative pressure channel16. To control the shut-off device26, a purely mechanical coupling can be provided with the lid27of the rotor housing or a sensor-controlled drive, similar to whatFIG. 3shows.

Here, a slider26ais provided as shut-off device26that connects the rotor housing15and the intermediate chamber18alternately with the negative pressure channel16. During a regular spinning operation, the rotor housing15is connected to the negative pressure channel16to maintain the spinning negative pressure pSUin the rotor housing15in the usual way. On the other hand, the intermediate chamber18is closed against the negative pressure channel16during the regular spinning operation. Nonetheless, owing to the connective opening19towards the rotor housing, a negative pressure builds up in the intermediate chamber. The slider26acan now be controlled in such a way that when the rotor housing15is opened, the connection of the rotor housing15to the negative pressure channel16is closed, while the third opening22is opened and the intermediate chamber18is now connected to the negative pressure channel16. Thus, pressure equalization with the surrounding air pressure PUtakes place only in the opened rotor housing15, but not in the negative pressure channel16, while the intermediate chamber18continues to be impinged with negative pressure through the third opening22.

The advantage of this embodiment is that no separate negative pressure line16ais necessary for the intermediate chamber18to maintain the negative pressure in the intermediate chamber18, even while and after the rotor housing15is opened. Additionally, owing to the fact that during the spinning operation the intermediate chamber18is closed against the negative pressure channel16, no air current is generated from the rotor housing15through the intermediate chamber18into the negative pressure channel16; rather, an advantageous air current is generated from the drive housing17through the intermediate chamber18into the rotor housing15. As a result of this, dirt deposits can largely be prevented in the intermediate chamber18.

If full spinning negative pressure PSUprevails in the intermediate chamber18even with an opened rotor housing15in such a solution, then no dirt will be sucked into the drive housing17when the rotor housing15is opened; rather, impurities will be sucked out by the intermediate chamber18in the negative pressure channel16. Such a solution therefore differs from the drawing shown inFIG. 4and can be used even if no axial air bearing24ais provided.

Another embodiment of the open-end spinning device1with an intermediate chamber18impinged with negative pressure, usable especially for bearings without an axial air bearing24a, is shown inFIG. 5. Here, the intermediate chamber18is connected to a negative pressure source23by means of an own negative pressure channel16a, as described inFIG. 3. However, another alternative is also possible, namely to provide only one negative pressure channel16and to block off the rotor housing15against the negative pressure channel16when it is opened by means of a shut-off device26. With regard to possible embodiments of the shut-off device26, please refer to the explanation inFIG. 3.

Furthermore, the drive housing17is provided with a purge opening35, through which the drive housing17can be supplied temporarily, preferably when the rotor housing15is opened, with dust-free purge air to flush out the impurities that could have penetrated the drive housing17to the intermediate chamber18. To supply filtered surrounding air to the drive housing17with the surrounding air pressure pU, the purge opening35is provided with a filter30or is connected to a filter30.

According to this explanation, a purge line36is connected to the purge opening35that is, in turn, provided with a filter30and is closed by the lid27of the rotor housing15during the spinning operation. When the rotor housing15is opened, the purge line36is then connected to the surrounding air, so that dust-free purge air is supplied to the drive housing17. Since purging takes place only when the rotor housing15is open, the purge opening35can be of relatively generous dimensions so fast thorough purging can be achieved.

A further embodiment of an open-end spinning device1, in which the penetration of impurities into the drive housing17is prevented, is shown inFIG. 6. Unlike inFIGS. 2 and 3, the intermediate chamber18is constantly impinged with surrounding air pressure PUor is connected to it. In this spinning device1, an air current is generated due to the intermediate chamber18from the third opening22through the first connective opening19into the rotor housing15. Thus, no negative pressure occurs in the drive housing17even during the spinning, but depending on the bearing type used therein, either the surrounding air pressure PUtoo or, if an axial air bearing24ais used, an increased air pressure PAGcompared to the surrounding air pressure PU. Different from the drawing shown with an axial air bearing24a, it is therefore just as possible to use the spinning device1in connection with other bearing types.

The relationships during the regular spinning operation are shown inFIG. 6, as inFIGS. 2 and 3. Since no negative pressure builds up in the drive housing17during the spinning operation, air carrying the respective impurities cannot be sucked in any longer even if the rotor housing15is opened. To keep preventing the sucking in of impurities through the third opening22and the connecting opening19into the rotor housing15, it is advantageous to provide the third opening22with an air filter30, as shown inFIG. 6.

The invention is not restricted to the embodiments shown. Variations and combinations as part of the patent claims fall also under the invention.

LIST OF REFERENCE CHARACTERS