EP4334622A1

EP4334622A1 - Multimedia rotary union and method for operating same

Info

Publication number: EP4334622A1
Application number: EP22725830.8A
Authority: EP
Inventors: Eberhard Grimm
Original assignee: Deublin GmbH
Current assignee: Deublin GmbH
Priority date: 2021-05-05
Filing date: 2022-04-26
Publication date: 2024-03-13
Also published as: WO2022233651A1; JP2024516877A; US20240240736A1; JP2024516878A; US20240229993A1; EP4334620A1; JP2024516853A; US20240240738A1; JP2024516879A; EP4334619A1; WO2022233652A1; WO2022233649A1; US20240240737A1; EP4334621A1; WO2022233650A1

Abstract

The invention relates to a multimedia rotary union (10) for transferring various fluid media having different viscosities from a stationary machine part to a rotating machine part, comprising: a stationary housing part (12) for mounting into the stationary machine part and having a main media channel (20) into which fluid media can be introduced with the application of pressure; a rotor (16) for connection to the rotating machine part (18) and having a rotor fluid channel (17) which is fluidically connected to the main media channel (20) of the stationary housing part (12); a mechanical face seal (30) between the stationary housing part (12) and the rotor (16), the mechanical face seal (30) comprising a rotor sliding ring (38) rotating with the rotor (16) and a stator sliding ring (36), the stator sliding ring (36) or the rotor sliding ring (38) being fastened to an axially movable sliding ring carrier (34), whereby an axially movable sliding ring arrangement (32) is formed, the medium pressure in the rotary union (10) exerting a first axial force component (K1) onto the axially movable sliding ring arrangement (32), which then acts on the mechanical face seal (30); and a loading device (100) acting on the axially movable sliding ring arrangement (32), said loading device being activated by the medium pressure in the rotary union (10) when the medium pressure in the rotary union (10) exceeds a predefined threshold value (pS) and, when activated, exerting an additional, second axial force component (K2) onto the sliding ring arrangement (32) which controls the closing force of the mechanical face seal (30).

Description

MULTIMEDIA ENABLED FILTRATION AND METHOD OF OPERATING SUCH

description

field of invention

The invention relates to a rotary feedthrough suitable for multimedia for transferring different fluid media with different viscosities from a stationary machine part to a rotating machine part in general and a rotary feedthrough suitable for multimedia, in which different media, in particular with very different viscosities, e.g. compressible media on the one hand and higher-viscosity incompressible media on the other hand , can optionally be introduced into the rotary union under pressure in particular.

Background of the Invention

Rotary feedthroughs are typically used to feed fluid media into a rotating machine part, eg a rotating spindle of a machine tool. For this purpose, the rotary feedthrough contains a seal between stationary components and rotating components. This seal can be designed as an axial mechanical seal. Typically, in an axial mechanical seal, two sliding rings or sliding sealing rings slide on one another, with one of the sliding rings rotating relative to the other coaxially to the axis of rotation and the sliding rings seal against each other with their opposite, adjacent annular end faces in order to keep the interior space, which is pressurized with a fluid medium, against the atmospheric pressure in the to seal the outside area. The type of fluid media to be transmitted by means of a rotary feedthrough can vary and can include, in particular, compressible media such as gases, e.g. compressed air, and liquid media, such as cooling lubricants, also known as cooling lubricants (KSS), and oils, such as cutting oil or hydraulic oil. Cooling lubricant (KSS) mostly consists essentially of an oil-water emulsion and typically has a viscosity that is not very much greater than the viscosity of pure water, which means it has a relatively low viscosity. In contrast, cutting oil and hydraulic oil have a significantly higher viscosity, which can be up to 60 mm ² /s (cSt) or more. Another well-known method is the so-called minimum quantity lubrication (MMS/MQL). This typically uses an aerosol in the form of an oil-gas mixture, i.e. essentially a compressible medium.

There is a large number of rotary feedthroughs, which are usually more or less optimized for one or a few specific of the aforementioned fluid media and/or for specific ranges of permissible operating parameters. Although rotary feedthroughs are also known which can be operated with different fluid media with different properties or viscosities, it has been shown that these are sometimes not universal or reliable to the desired extent. For example, under certain conditions and/or with some media, these can overheat under certain circumstances, for example at high speeds, which can lead to the destruction of the rotating union. Among other things, it has been shown that some supposedly universal rotating unions, for example when running dry or with compressed air at high speeds, can have considerable problems in terms of stability. The rotating operation of a rotary union without pressurization with a medium is typically referred to as dry running.

Furthermore, conventional rotary unions can sometimes have a relatively high leakage rate in compressed air operation, e.g. of up to 100 standard liters per minute or more, which can also be undesirable.

The Deublin Company patents EP 1 744 502 B1 and EP 2 497978 B1 describe a technology in which the load ratio (sometimes also referred to as the balance ratio) of the mechanical seal is in a specially preselected interval, and in a wide pressure and speed range a suitable contact pressure between the two sliding rings is guaranteed. Deublin's technology is also known among experts as AutoSense®.

Overall, many of the conventional rotary unions available on the market differ in terms of the entirety of the sometimes conflicting requirements placed on rotary unions, such as the area of application of the operating parameters, diversity with regard to the fluid media that can be used, stability, simplicity for the user, universality, etc more or less limited.

From the applications DE 102021 111 688 and DE 10 2021 111 670 of the same applicant, both filed on May 5, 2021 and not previously published, which are hereby incorporated by reference, rotary unions suitable for multimedia are known which have two different load ratios for media of different viscosity, wherein the load conditions are controlled via different media inlet channels. However, for some applications, the multiple media ports required for this may be less desirable.

General Description of the Invention

The invention has set itself the task of providing a multi-media suitable rotary feedthrough which is suitable for various media, in particular compressible media, e.g. compressed air on the one hand and incompressible media with high viscosity, e.g. cutting oil or hydraulic oil on the other.

A further aspect of the task is to provide a multi-media-capable rotary feedthrough which has a low leakage rate when operating with different media, viscosities and pressures and which also works at high speeds with a long service life and with little wear.

Another aspect of the task is to provide a multimedia-capable rotary union that can be used with both i) cutting or hydraulic oil, ii) with cooling lubricant (KSS), iii) with compressed air, iv) with aerosol media for Small quantity or minimum quantity lubrication as well as v) medium-free and pressureless, ie in dry running at high speeds works durable and low-wear.

A further aspect of the task is to provide a multimedia-capable rotary feedthrough which reconciles great universality (“one-for-all”) and ease of use for the user and which enables backwards compatibility for users of conventional rotary feedthroughs.

A further aspect of the task is to provide a rotary feedthrough which does not have the disadvantages described above, or only has them to a lesser extent.

The object of the invention is solved by the subject matter of the independent claims. Advantageous developments of the invention are defined in the dependent claims.

According to one aspect of the invention, a multi-media suitable rotary feedthrough is provided for transferring different fluid media, including both compressible and incompressible media and media with different, in particular high, viscosities in the same rotary feedthrough from a stationary machine part to a rotating machine part. The rotary union comprises a stationary housing part for installation in the stationary machine part and a rotor for connection to the rotating machine part. The stationary housing part encloses an in particular (co)axial main media channel with a central working space in the form of an axial or central inner stator fluid channel. The rotor, e.g. in the form of a hollow shaft, also has an axial or central rotor fluid channel, with the fluid channels of the stationary housing part and the rotor being in fluid communication with one another permanently, i.e. also during rotation, such that the rotor is in fluid contact with one another relative to the stationary Housing part, if necessary, can rotate at a high speed, and the respective pressurized medium flows during rotation from the main media channel of the stationary housing part into the rotor fluid channel of the rotating rotor in order to be guided out of the rotor fluid channel into the connected rotating machine part. The stationary housing part can be designed in one piece or in several pieces.

The rotary union includes an axial face seal between the stationary housing part and the rotor which seals fluid communication between the rotor and the stationary housing part during rotation. For this purpose, the mechanical seal comprises a sliding ring or sliding sealing ring rotating with the rotor, the so-called rotor sliding ring, and a non-rotating sliding ring or sliding sealing ring, the so-called stator sliding ring, with the two sliding rings with their opposite and relatively rotating annular sealing surfaces forming the transition between the stationary and the rotating area seal the rotary union. So that the mechanical seal can open in a controlled manner, for example in unpressurized dry running or in compressed air operation, at least one of the two mechanical seals is suspended so that it can move slightly axially. For this purpose, this sliding ring is attached to an axially movably mounted sliding ring carrier, so that the sliding ring carrier and the associated sliding ring have an axial form movable mechanical face assembly, and the face seal can open and close by axial movement of the face assembly, so the face ring carrier with the face ring attached. From a structural point of view, it is usually easier to hang the stator slip ring so that it can move axially. In this case, the axially movable seal ring carrier forms an axially movable stator seal ring arrangement with the stator seal ring attached thereto. The stator slip ring assembly is axially slidably supported in the inner stator fluid passage of the stationary housing portion by the slip ring carrier and is preferably able to accommodate some angular play to ensure a precise seal between the abutting sealing surfaces of the two slip rings. Such an axially displaceable and possibly slightly tiltable (stator) sliding ring is also referred to in the technical world as a floating (stator) sliding ring.

In other words, in the case of a floating stator slip ring, the slip ring seal comprises a slip ring arrangement which is axially movable in the stationary housing part but does not rotate, with the stator slip ring and a complementary rotor slip ring which rotates with the rotor. The rotor sliding ring can, for example, be fastened, for example pressed and/or glued or fastened in some other way, to the end face of the rotor facing the stationary housing part.

However, it should not be ruled out that the arrangement of the floating seal ring and the seal ring complementary thereto should be reversed, that is to say to suspend the rotor seal ring in an axially movable manner in order to form the rotor seal ring as a floating seal ring. In both cases, the mechanical seal can be designed with Pop-Off® functionality. The sliding ring arrangement consisting of the sliding ring carrier and the sliding ring can optionally be designed in one piece.

When the main media channel is subjected to medium pressure, the medium flows through the mechanical seal into the fluid channel of the rotor. At the same time, the axially movable slide ring arrangement is subjected to the medium pressure, which exerts a first axial force component on the axially movable slide ring arrangement, which acts in a closing manner on the mechanical seal. This closing acting first axial force component depends on the load ratio, i.e. on the geometric surface ratios of the mechanical seal and increases proportionally with the applied medium pressure.

In order to be able to additionally influence the axial closing force on the mechanical seal, the rotary feedthrough according to the invention now also has an axially movable clamping device within the stationary housing part, which acts on the axially movable mechanical ring arrangement and defines a non-activated and an activated state. The clamping device is activated by the medium pressure present in the main media channel when the medium pressure in the main media channel exceeds a predefined pressure threshold value as a pressure switching value. The tensioning device is thus activated hydraulically, ie switched on hydraulically. If the medium pressure falls below the pressure threshold value again, the tensioning device is deactivated again, ie switched off hydraulically. In other words, the tensioning device switches from the non-activated state to the activated state in response to the medium pressure in the rotary union exceeding the predefined pressure threshold value. In response to the medium pressure in the rotary union falling below a predefined pressure threshold value, the tensioning device switches back from the activated state to the non-activated state.

In the activated state, the tensioning device generates an additional second axial force component which, in addition to the medium pressure-proportional first axial force component, acts on the axially movable slide ring arrangement and thus contributes to the closing force of the slide ring seal, in particular increasing the closing force of the slide ring seal between the stator seal ring and the rotor seal ring. In other words, in the non-activated state of the clamping device, the second axial force component does not act, so that the closing force of the mechanical seal is caused only by the first axial force component, and in the activated state of the clamping device, the first and second axial force components add up to form a total closing force , which in particular is greater than the first axial force component defined by the load ratio.

If the clamping device is not activated, the mechanical seal preferably works as a balanced mechanical seal, in which the load ratio is selected such that the mechanical seal is at least predominantly, if necessary exclusively, hydraulically or pneumatically balanced. Corresponding rotary feedthroughs with a load ratio in a specific range are given the designation Autosense® by the applicant. A special feature of the present rotary union is that the mechanical seal works as a balanced mechanical seal below the pressure threshold value, i.e. as long as the clamping device is not activated, and when the pressure threshold value is exceeded, the clamping device is activated or switched on hydraulically, which causes an increase in the closing force .

Preferably, the tensioning device is mounted in the stationary housing part so that it can move axially relative to the slip ring arrangement in order to apply the additional second axial force component to the slip ring arrangement, e.g. by the tensioning device pressing axially against the slip ring arrangement.

The mechanical seal with the floating slide ring defines a load ratio B = FH / F, where FH is the surface of the slide ring arrangement that is hydraulically or pneumatically loaded by the medium pressure and F is the contact area between the stator slide ring and the rotor slide ring. The first axial force component on the face assembly is based on the load ratio of the face seal, regardless of whether the tensioner is activated or not, i.e. the same with activated or not activated tensioner, and increases proportionally with the medium pressure in the rotary union. The second axial force component generated by the tensioner on the slip ring assembly is now added to the first axial force component based on the load ratio, resulting in a total closing force acts on the mechanical seal, which is formed as the sum of the first and second axial force components if and only if the medium pressure exceeds the pressure threshold and has activated the clamping device. In particular, the additional second axial force component is not effective if and as long as the medium pressure remains below the pressure threshold.

In other words, when the pressure threshold value is exceeded, the clamping device switches on an additional second axial force component such as a booster, which increases the closing force disproportionately to the first axial force component. Accordingly, the tensioning device forms a closing force boosting device which is switched on when the pressure threshold value is exceeded. The switching on of the closing force boosting device takes place in particular hydraulically by the medium pressure.

As a result, e.g. with compressed air operation below the pressure threshold, i.e. with a relatively low pressure, e.g. less than or equal to 10 bar, the mechanical seal can be operated in a balanced manner with the load ratio B, with the load ratio B allowing a controlled (slight) opening of the mechanical seal with controlled desired Allows air leakage and is therefore suitable for compressed air operation under rotation. When the main media channel is pressurized with a higher-viscosity, incompressible medium, e.g. cutting oil or hydraulic oil with a higher pressure, in particular greater than 10 bar, the clamping device switches on, causing an increase in the closing force, which is suitable for higher-viscosity cutting oil or hydraulic oil and an excessive one avoids leakage.

For example, cutting oil can have a viscosity in the range from 6 mm ² /s to 18 mm ² /s and hydraulic oil can have a viscosity in the range from 32 mm ² /s to 46 mm ² /s (40° C.), possibly even up to 60 mm ² /s (40°C). With the activated clamping device, the rotary leadthrough can also be operated with a low-viscosity liquid medium, eg cooling lubricant (KSS), eg with a viscosity in the range from 1 mm ² /s to 3 mm ² /s.

As a result, the rotary ^leadthrough can be operated both with the compressible media and with the incompressible media, each at high speeds, for example up to greater than or equal to 24,000 rpm, without the slide rings heating up excessively. Nevertheless, the rotary leadthrough can, on the one hand, have an acceptably low air leakage rate in compressed air operation and, on the other hand, work with an incompressible or liquid medium, also of higher viscosity, essentially without leakage.

In compressed air operation, a small gap (controlled opening of the mechanical seal) is advantageously created between the two sealing surfaces of the mechanical seal, so that there is no wear and an intentional, controlled, minor air leak occurs. In the case of liquid media with high viscosity, such as cutting oil or hydraulic oil, on the other hand, the two slide rings are pressed against each other with the increased closing force, ie the slide ring seal is closed so that an enlargement of the gap is avoided. The rotary union therefore preferably defines at least two operating states as follows:

1. When pressure is applied with a medium pressure below the pressure threshold value, the rotary union defines a compressed gas operating state for operation with a compressible medium. In the pressurized gas mode, the mechanical seal is minimally open to allow controlled leakage. In the pressurized gas mode for compressible media, the tensioning device is not activated. So only the first axial force component acts based on the load ratio.

2. When pressurized with a medium pressure above the pressure threshold value, the rotary union defines a liquid medium operating state for compressible media under a high medium pressure. In the liquid medium operating state, the mechanical seal is closed and the tensioning device is activated. Accordingly, in the liquid medium operating state, the first axial force component acts on the mechanical seal based on the load ratio B and, in addition, the second axial force component, caused by the activated tensioning device, added together as a common closing force. As a result, adequate tightness can be achieved for operation with highly viscous media such as cutting oil or hydraulic oil at a high medium pressure.

Switching between the compressed gas operating state and the liquid medium operating state takes place hydraulically by the medium pressure present in the rotary union.

In this way, a universal multi-media-capable rotary feedthrough can be created in an advantageous manner, which is suitable when pressure is applied with very different media, namely compressible media on the one hand, e.g. compressed air, and highly viscous liquid media on the other, e.g. cutting oil or hydraulic oil, with high stability at high speeds and low leakage rate for all of the media used, especially for liquid media essentially leak-free.

If there is no medium pressure in the main media channel, there is no closing force on the mechanical seal. Optionally, a secondary seal can retract the floating slide ring in the depressurized state (so-called PopOff@ function). As a result, there is no contact between the sliding ring sealing surfaces when running dry and dry running at high speeds can also take place indefinitely.

The rotary leadthrough can therefore define a third operating state, namely the dry-running operating state. The dry-running operating state occurs when there is no pressure in the rotating union, with the mechanical seal being in a fully open state. In the fully open dry-running operating state, the two seal rings are separated from one another by a sufficiently large gap, so that the rotary union can rotate dry-running without medium, without wear occurring on the seal rings. The additional second axial force component, which the tensioning device exerts on the slide ring arrangement when the medium pressure has exceeded the predefined pressure threshold value, can itself be pressure-independent or - in the pressure range above the pressure threshold value - pressure-dependent on the medium pressure, there, for example, be proportional to the medium pressure. The second axial force component can thus be constantly zero in the pressure range from 0 bar up to the pressure threshold value and, for example, increase discontinuously at the pressure threshold value and/or increase proportionally above the pressure threshold value.

The tensioning device can have one or more springs, which are tensioned against the stationary housing part by the medium pressure present in the main media channel.

For example, if the spring tension exceeds a predetermined threshold, the tensioner may be activated and apply the additional second axial force component to the slip ring assembly if and only if the spring tension threshold is exceeded.

According to an exemplary embodiment, the slide ring carrier has an outer (ring) flange on which the tensioning device acts in order to transmit the additional second axial force component of the tensioning device to the slide ring arrangement.

Furthermore, the tensioning device can have a force distribution ring, which distributes the additional second axial force component exerted by the tensioning device in a ring shape evenly over the slide ring carrier, e.g. over the flange.

The tensioning device preferably has one or more spring-loaded pistons in the stationary housing part, which are actuated by the medium pressure in the rotary feedthrough and, in the actuated state, exert the second axial force component on the slide ring arrangement. In other words, the at least one piston is tensioned by the medium pressure against the spring force and exerts the additional second axial force component of the tensioning device on the slide ring arrangement if and only if the medium pressure in the rotary union exceeds the pressure threshold value.

For this purpose, one or more axial bores are preferably provided in the stationary housing part, in which the spring-loaded piston or pistons are each mounted so as to be axially displaceable and are tensioned against the respective spring by the applied medium pressure.

The spring-loaded piston or pistons are preferably sealed in the respective associated axial bore by means of a sealing ring, so that the pressurized medium essentially cannot escape via the spring-loaded piston or pistons According to an exemplary embodiment, the medium pressure from the main media channel acts on a rear end face (facing away from the rotor) of the piston or pistons in order to move the piston or pistons under pressure in the respective axial bore in the stationary housing part against the spring load in the direction of the mechanical seal.

The tensioning device preferably has at least two or three, preferably two to six, preferably two, three or four spring-loaded pistons which are arranged in particular uniformly around the slide ring carrier in the stationary housing part. For example, with two radially opposite spring-loaded pistons, a symmetrical application of force to the slide ring arrangement can be made possible and tilting of the slide ring arrangement can be prevented. Furthermore, this has proven to be advantageous with regard to backwards compatibility and, among other things, for reasons of space within the rotary feedthrough.

According to one embodiment, the spring-loaded piston or pistons rest axially against the outer flange of the slide ring carrier or axially against the force distribution ring when the pressure threshold value is exceeded in order to apply the additional second axial force component of the tensioning device directly to the outer flange or directly to the force distribution ring transferred, which can be economical in terms of spatial conditions within the stationary housing part.

For example, the stationary housing part has a stop for the spring-loaded piston or pistons, which limits the axial flow of the spring-loaded piston or pistons in that the spring-loaded piston or pistons strike against the respective associated stop when the pressure threshold is exceeded and activates the tensioning device is. Furthermore, the spring-loaded piston(s) can each have a closing force activation spring which, in the activated state of the tensioning device, exerts a constant spring force on the slide ring arrangement that is independent of the medium pressure, so that the additional second axial force component exerted by the tensioning device on the slide ring arrangement is constant, independent of the medium pressure, if and as long as the clamping device is activated.

The pressure threshold is preferably greater than the maximum permissible operating pressure of the rotating union for compressed air operation. This ensures that the clamping device is not activated in the entire permissible pressure range for compressed air operation and that the rotating union rotates in compressed air operation with the load ratio and without the additional second force component, so that an air gap can form and controlled air leakage can take place (AutoSense®). For this purpose, the pressure threshold value can be greater than 5 bar, preferably greater than or equal to 10 bar, preferably between 5 bar and 100 bar, preferably between 10 and 50 bar, preferably between 10 bar and 30 bar. In other words, the pressure threshold value is preferably selected at least so high that the closing force boosting device is not activated in compressed air operation, ie remains switched off The rotary feedthrough also has a connection port for connecting a media pressure line in order to introduce the desired media into the media main channel with a medium-specific desired medium pressure. The rotary feedthrough is preferably a single-port rotary feedthrough, ie it has only a single connection port for connecting a media pressure line and a single main media channel through which (alternatively) all desired different media are passed. The rotary feedthrough is therefore prepared so that both compressible media, in particular compressed air and incompressible media, in particular cutting oil or hydraulic oil, can be introduced under pressure into the same main media channel via the same connection port. All media are introduced alternatively (not simultaneously) via the same connection port and an increase in pressure of the medium currently present above the pressure threshold value in the single main media channel causes the clamping device to be switched on hydraulically and/or the pressure drop of the medium currently present in the single main media channel below a pressure threshold value switching off the clamping device

Advantageously, the rotary feedthrough can thus manage with a single connection port for connecting a media pressure line in order to introduce all desired media into the media main channel, each with an associated medium-specific desired medium pressure, and the rotary feedthrough is nevertheless suitable for both compressible media, in particular compressed air, and Incompressible media, in particular cutting oil or hydraulic oil, can be fed into the same main media channel under pressure via the same connection port, with the closing force of the mechanical seal advantageously being within a suitable range for all medium pressures, i.e. controlled air leakage for compressed air operation or MQL/MQL with relatively low medium pressure and Reliable closing of the mechanical seal when operating with cutting oil, hydraulic oil or KSS with a relatively high medium pressure.

The connection port is preferably a (co)axial connection port. However, with regard to special customer requirements, it should not be ruled out in principle to use a radial connection port and/or several connection ports, although these are not required for the multi-media suitability of the rotary feedthrough.

The main media channel preferably runs (co)axially, in particular from the connection port to the mechanical seal. The main media channel is preferably permanently open from the connection port to the mechanical seal, ie the coaxial main media channel itself preferably does not contain a valve that would interfere with the flow of media from the connection port through the main media channel into the rotor fluid channel. In this way, among other things, an undesired segregation in the main media channel can be avoided, for example if the rotary union is operated with minimum quantity lubrication (MMS/MQL). The user sets the currently desired medium and the respective medium pressure on a media distribution network outside the rotary union. For this purpose, at least two media sources, two media supply lines, a distributor and external valves in the media supply lines for the different media, in particular with different viscosities, in particular both at least one compressible medium, such as compressed air, and at least one incompressible liquid medium, such as e.g Cutting oil, hydraulic oil or KSS includes. The medium supply lines, in particular for compressed air on the one hand and for cutting oil, hydraulic oil or KSS on the other hand, are interconnected outside the rotary union via the distributor in order to select the desired medium from outside the rotary union by means of external valves and to supply this with the desired medium pressure via the single connection port Initiate the, preferably single, main media channel. This means that all permitted media are switched on and off alternatively outside the rotary feedthrough and preferably fed into the rotary feedthrough alternatively, ie one after the other, via the same connection port.

Preferably, the load ratio of the mechanical seal is in the range of about 0.40 to 0.65, preferably in the range of about 0.45 to 0.60, preferably in the range of about 0.47 to 0.60, preferably in the range of about 0.50 to about 0.57. In compressed air operation, this enables controlled opening of the mechanical seal and thus controlled air leakage that is not excessively large.

The slide ring carrier is preferably mounted and sealed so that it can move axially in the stationary housing part by means of an elastomeric secondary seal. The secondary seal may, for example, comprise an elastomer ring which is arranged on the outer diameter of the face ring carrier and has, for example, a U-shaped cross-section. When the mechanical seal is closed under pressure, the secondary seal can be axially tensioned and, when the pressure is released, can pull the mechanical seal carrier with the stator seal ring away from the rotor seal ring in order to open the mechanical seal sufficiently far for dry running (so-called PopOff® function). The opening of the mechanical seal in dry running can therefore be supported, for example, by restoring the elastomer ring. This can contribute to practically unlimited wear-free dry running at high speeds.

At least one of the two slide rings, in particular both slide rings of the slide ring seal, is preferably designed as a silicon carbide slide ring (SiC).

The rotating union is connected and operated as follows, for example:

The user connects an external compressed gas source via an external compressed gas supply line and an external distributor, e.g. a multi-way valve, to the connection port of the rotary union and an external media reservoir with an incompressible liquid medium, such as oil, in particular cutting oil or hydraulic oil with a viscosity of greater than or equal to 6 mm ² /s, or KSS, via an external liquid medium pressure supply line and via the external manifold to the same connection port of the rotating union. During operation, compressed gas, e.g. compressed air, at a lower pressure than the oil or the cooling lubricant, in particular at a pressure of less than or equal to 10 bar, is then introduced into the main media channel in a first time interval via the compressed gas supply line and the connection port, with the clamping device not is activated and the rotating union rotates with the pressurized gas and with a closing force on the mechanical seal which is defined by the load ratio of the mechanical seal and a controlled gas leakage takes place, and the pressurized gas is later switched off again.

In a second subsequent time interval, the incompressible liquid medium, in particular cutting oil or hydraulic oil with a viscosity of greater than or equal to 6 mm ² /s or cooling lubricant, is fed via the liquid medium pressure supply line, the external distributor and the same connection port, with a higher pressure than the compressed gas, in particular with a pressure greater than 10 bar, into the main media channel, whereby the tensioning device is activated by the higher pressure of the liquid medium, i.e. it is switched on hydraulically, and the rotary union rotates with the liquid medium and with an added closing force on the mechanical seal, whereby the added closing force is composed of the first axial force component and the additional second axial force component, the first axial force component being generated by the load ratio of the liquid pressure and the additional second axial force component being generated by the activi first clamping device is generated. The incompressible liquid medium is later switched off again, as a result of which the tensioning device is deactivated again.

Thus, the rotary union can be operated sequentially with different media, including both compressible and incompressible media, at the appropriate pressures via the same connection port and the same main media channel, and in response to the increase in the medium pressure above the pressure threshold, the clamping device switches on to increase the closing force strengthen.

Then, in a third time interval, the rotary union can rotate dry-running without medium, with the tensioning device not being activated and the mechanical seal being kept open, in particular by the secondary seal, e.g. by the U-cup ring.

The rear end of the slide ring carrier remote from the slide ring seal preferably opens into the working space or main media channel, which in particular runs coaxially with the rotor, the slide ring seal and/or the slide ring carrier. The rotor preferably has only a single central rotor fluid channel. Furthermore, the rotary feedthrough preferably has only a single axial face seal.

The invention is explained in more detail below using exemplary embodiments and with reference to the figures, in which identical and similar elements are sometimes provided with the same reference symbols and the features of the various exemplary embodiments can be combined with one another. Brief description of the characters

Show it:

1 shows a longitudinal section through a rotary feedthrough according to an embodiment of the invention with the mechanical seal open,

Fig. 2 like Fig. 1, but with the mechanical seal in the condition for compressed air operation and not activated clamping device,

Fig. 3 as Fig. 1, but with closed mechanical seal for operation with incompressible media and activated clamping device,

FIG. 4 shows an enlarged detail of the sliding ring arrangement and the clamping device from FIG. 1,

FIG. 5 shows an enlarged detail of the sliding ring arrangement and the clamping device from FIG. 2,

FIG. 6 shows an enlarged detail of the sliding ring arrangement and the clamping device from FIG. 3,

7 shows a longitudinal section through a rotary feedthrough according to a further embodiment of the invention with the mechanical seal open,

Fig. 8 like Fig. 7, but with the mechanical seal in the condition for compressed air operation and not activated clamping device,

Fig. 9 as Fig. 7, but with closed mechanical seal for operation with incompressible media and activated clamping device,

FIG. 10 shows an enlarged detail of the sliding ring arrangement and the clamping device from FIG. 7,

FIG. 11 shows an enlarged detail of the sliding ring arrangement and the clamping device from FIG. 8,

FIG. 12 shows an enlarged detail of the sliding ring arrangement and the clamping device from FIG. 9,

13 shows a longitudinal section through a rotary feedthrough according to a further embodiment of the invention with the mechanical seal open,

Fig. 14 like Fig. 13, but with the mechanical seal in the condition for compressed air operation and not activated clamping device,

Fig. 15 as Fig. 13, but with closed mechanical seal for operation with incompressible media and activated clamping device,

FIG. 16 shows an enlarged detail of the sliding ring arrangement and the clamping device from FIG. 13,

FIG. 17 shows an enlarged detail of the sliding ring arrangement and the clamping device from FIG. 14,

FIG. 18 shows an enlarged detail of the sliding ring arrangement and the clamping device from FIG. 15,

19 shows a schematic representation of the diameter ratios of a sliding ring arrangement with a floating sliding ring for calculating the load ratio B,

20 shows a schematic representation of an external media distribution network.

DETAILED DESCRIPTION OF THE INVENTION Referring to FIGS. 1 to 18, the bushing 10 has a stationary housing part 12 at the rear, which in the present examples is constructed in several parts. A rotor 16, in these examples in the form of a Hollow shaft for connection to a machine spindle 18 is rotatably mounted in the stationary housing part 12 with primary roller bearings, for example ball bearings 14 . The rotary union 10 has in particular a single main media channel 20 in the stationary housing part 12 and a single connection port 22, e.g Introduce pressurization via the same connection port 22 into the same main media channel 20 extending coaxially to the axis of rotation X of the rotary feedthrough 10 . In this case, the media main channel 20 is pressurized alternatively and not simultaneously with the currently desired medium from a group of suitable media. The group of suitable media includes both compressible and incompressible media. The group of suitable media can include compressed air, minimum quantity lubrication or minimal quantity lubrication (MMS/MQL) as compressible media on the one hand, and cooling lubricant (KSS), cutting oil and/or hydraulic oil as incompressible media on the other. The rotary leadthrough can be operated in particular at least with compressed air on the one hand and an oil, for example cutting oil or hydraulic oil, on the other hand.

The stationary housing part 12 and the rotor 16 are sealed by means of an axial face seal 30 . The mechanical seal 30 comprises a mechanical seal assembly 32 with an axially displaceable mechanical seal carrier 34 and a mechanical seal 36 fastened to the mechanical seal carrier 34. The mechanical seal 36 of the stator, or stator mechanical seal 36 for short, seals with its rotor-side axial annular sealing surface 36a against a rear axial annular sealing surface 38a of the complementary mechanical seal 38 of the rotor 16. The sliding ring 38 of the rotor 16 or rotor sliding ring 38 for short is fastened to the stator-side end face 16a of the rotor 16, in these examples pressed and/or glued into an annular groove 42, although other fastening techniques are also possible.

The slide ring carrier 34 of the stator slide ring 36 is designed, for example, as a hollow piston 44 and is mounted in the stationary housing part 12 in particular so that it cannot rotate, but can move axially. The slide ring carrier 34 has a flange 46 on the rotor side, which is housed in a corresponding recess 48 on the rotor side in the stationary housing part 12 so that it cannot rotate. The anti-twist device can be realized, for example, by means of two axial pins in the stationary housing part 12, which create a form fit in opposite grooves on the slide ring carrier flange 46 (not shown in the figures for the sake of clarity). The stator sliding ring 36 is fastened on the face side to the rotor-side end 34a of the sliding ring carrier 34 or hollow piston 44, e.g. pressed in or glued, although other fastening techniques are also possible. In the present examples, the stator sliding ring 36 is, for example, permanently fastened in a recess 52 in the sliding ring carrier 34 , more precisely in the flange 46 .

In the present example, the closing of the mechanical seal 30 can be improved by an inner screen 45 in the axial bore 47 of the hollow piston 44 .

The stationary housing part 12 is preferably designed as a multi-part lead-through housing, so that due to the modular design, it can be easily adapted to existing housing shapes. In the In the present example, the stationary housing part 12 is in three parts and comprises a rotor housing 12a, in which the rotor 16 is mounted by means of ball bearings 14, an intermediate housing part 12b, in which the slide ring arrangement 32 is mounted so that it can move axially and in which the clamping device 100 is arranged, and a rear Housing part 12c, in which the main media channel 20 extends axially and into which the connection port 22 leads axially. However, other housing shapes are also possible.

The slide rings 36, 38 are preferably both made of silicon carbide (SiC), so that the term SiC-SiC slide ring seal 30 is often used. A SiC-SiC mechanical seal 30 is durable and has excellent sealing properties when operating with liquid media that lubricate well. However, some conventional rotary unions have stability problems when operated with compressed air or when running dry with silicon carbide seals. For example, SiC sliding rings can overheat if they run without lubricant and are not sufficiently separated from each other, which can lead to the total failure of the rotating union. This can be avoided with the present invention. However, other materials for the sliding rings 36, 38, such as carbon-graphite (CG), e.g., a CG-SiC mechanical seal, or tungsten carbide/tungsten carbide (TC) can also be considered.

The sliding ring arrangement 32, in this example the stator or, for short, the stator sliding ring arrangement 32 or the hollow piston 44, is mounted in the stationary housing part 12 in an axially displaceable manner by means of a secondary seal 60. In these examples, the secondary seal 60 comprises a secondary sealing ring 64 in the form of an elastomeric ring seal. In the present examples, the elastomeric ring seal 64 has a U-shaped cross section with a groove 66 which is open on the high-pressure side and is in fluid communication with the main media channel 20 . This ring seal 64 is therefore sometimes referred to as a U-cup ring.

The mounting of the sliding ring carrier 34 or hollow piston 44 by means of the elastomer ring seal 64 allows the sliding ring arrangement 32 or the stator sliding ring 36 limited axial mobility in order to be able to close the axial mechanical seal 30 and open it again. Typically, the mechanical seal 30 is closed during operation with pressurized fluid media with liquid lubricant components, such as KSS, cutting oil or hydraulic oil, so that at most a minimal, possibly droplet-wise, leakage (so-called sweating) occurs. Such media ensure sufficient lubrication between the two silicon carbide sliding surfaces 36a, 38a when the mechanical seal 30 is closed. However, when running dry or when operating with compressed air in the closed state, the two silicon carbide sliding rings 36, 38 could rub against one another and heat up excessively. To avoid this, the mechanical seal 30 opens when there is no pressure or during compressed air operation, in that the sliding ring carrier 34 or hollow piston 44 with the stator sliding ring 36, i.e. the sliding ring arrangement 32, detaches from the rotor sliding ring 38 and moves slightly axially away from it in the present figures to the right. The elastomeric secondary seal 60 thus fulfills a dual function for the sliding ring arrangement 32, namely as an axially displaceable bearing on the one hand and as a seal in the stationary housing part 12 against the pressurization of fluid medium from the stationary side on the other hand.

Due to the mounting by means of the elastomeric sealing ring 64, the sliding ring arrangement 32 may also be able to tilt slightly, so that the sealing surfaces 36a, 38a of the two sliding rings 36, 38 of the mechanical seal as the primary seal 30 lie perfectly flat against one another in the pressurized state and produce a correspondingly good sealing effect be able. Such an axially displaceably mounted and possibly slightly tiltable stator sliding ring 36 is also referred to in the art as a floating sliding ring.

Referring to FIG. 19, the load ratio B of a floating slip ring is defined by the area ratio FH/F of hydraulically or pneumatically loaded area FH to the contact area F between the two slip rings 36,38. The load ratio B can thus be calculated geometrically using the diameters D1, D2 and D3 as follows:

F _H Dl ² — D3 ² ^{B ~} Ύ ^~ D2 ² — D3 ² where D1 is the outer diameter or effective diameter of the mechanical seal carrier under pressure, D2 is the outer diameter of the mechanical seal contact surface and D3 is the inner diameter of the mechanical seal contact surface.

If there is no medium pressure, the stator sliding ring assembly 32 is pulled back from the secondary seal 60 (to the right in the figures), whereby the sliding ring assembly 30 is completely opened, so that the mechanical seal 30 rotates dry-running without medium with a sufficient distance between the two sliding rings 36, 38 can. In this completely open state (FIGS. 1, 4, 7, 10, 13, 16) of the mechanical seal 30 there is a sufficiently large gap 39 between the sliding rings 36, 38 for dry running without medium.

When compressed air is applied to the main media channel 20, this occurs at a low medium pressure, eg with a maximum permissible pressure of 10 bar, so that the pressure threshold value ps is not exceeded and the clamping device or closing force boosting device 100 is not activated. As a result, only the closing first axial force component K1 acts on the sliding ring arrangement 32 on the sliding ring seal 30, which is generated by the load ratio B, which is approximately 0.5 to 0.57 in the present exemplary embodiment. The relatively small load ratio B creates a small sealing gap 40 which allows controlled air leakage, preventing wear on the sealing faces. If minimum quantity lubrication (MMS/MQL) is applied to the main media channel 20, this is preferably also done with a medium pressure below the pressure threshold value ps. As a result, only the first axial force component becomes effective, which is sufficient for the MMS/MQL to allow the MMS/MQL to flow into the fluid channel 17 of the rotor 16 in an essentially leak-free manner. 2, 5, 8, 11, 14, 17 show the operating state of the mechanical seal in compressed air operation, the sealing gap 40 in compressed air operation being so small that it cannot be shown in the figures.

The clamping device 100 is installed in the stationary housing part 12, specifically in the present examples to the rear of the flange 46 of the slide ring carrier 34. In the present example, the clamping device 100 comprises two radially opposite pressure pistons 102, which can be displaced axially in associated bores 104 in the stationary housing part 12 are arranged. The pressure pistons 102 are each held in a non-activated state by a compression spring 106 against the medium pressure, in the present example to the right, as long as the medium pressure does not exceed the predefined pressure threshold value. The pressure pistons 102 are thus accommodated in the stationary housing part 12 with opening pressure springs 106 .

The main media channel 20 is in fluid communication with a rear pressure chamber 108 in such a way that when pressure is applied to the main media channel 20, the medium pressure acts via the rear pressure chamber 108 on the respective rear end face 112 of the pressure piston 102 facing away from the rotor and the pressure pistons 102 act in the closing direction of the mechanical seal 30 against the springs 106 strains. The pressure pistons 102 are each sealed by means of a seal 114 in the associated bore 104 so that the medium pressure present in the pressure chamber 108 exerts an axial force component proportional to the pressure on the pressure piston 102 against the spring tension of the spring 106 . The spring tension of the spring 106 is now selected in such a way that the pressure pistons 102 are not activated, i.e. do not exert any force on the slide ring arrangement 32 as long as the medium pressure is below the predefined pressure threshold value ps.

The area ratios of the pressure piston 102 and the spring force of the spring 106 are therefore selected in such a way that the pressure pistons 102 do not exert any force on the stator sliding ring arrangement 32 below the pressure threshold value ps, as shown in FIGS , and the clamping device 100 is thus in a non-activated state. In this non-activated state of the clamping device 100, the closing force of the mechanical seal 30 is caused by the medium pressure exclusively according to the load ratio of the mechanical seal 30, i.e. based on the area ratio FH/F on the mechanical seal 30 as the closing first axial force component K1.

Referring to FIGS. 3, 6, 9, 12, 15, 18, the rotary union can be supplied with an incompressible liquid medium via the same connection port 22 and the same main media channel 20 with a significantly higher medium pressure, for example up to 140 bar, 210 bar or possibly higher , for example cutting oil, hydraulic oil or cooling lubricant. As soon as the medium pressure of the incompressible medium rises above the pressure threshold value ps, of about 10 bar in this example, the force acting against the spring force of the springs 106 by the medium pressure on the pressure piston 102 exceeds a threshold value of the spring force of the springs 106 in such a way that the pressure piston 102 as a plunger against the flange 46 of the slide ring carrier 34 and subject it to a closing second axial force component K2 in addition to the first axial force component K1. This amplifies the overall closing force on the face seal 30 beyond the closing force caused by the B load ratio.

If the medium pressure, in particular when using KSS or cutting oil/hydraulic oil, ie exceeds the predefined pressure threshold value ps, the clamping device 100 is activated and exerts the additional closing second axial force component K2 on the mechanical seal 30 . In the present examples, the pressure threshold value ps is selected to be equal to or slightly greater than the maximum permissible pressure for compressed air, ie ps^10 bar.

The clamping device 100 thus acts as a closing force amplification device, which is activated in response to the medium pressure in the main medium channel 20 exceeding the pressure threshold value ps and is not activated below the pressure threshold value ps. In the present exemplary embodiments, the clamping device 100 or closing force amplification device is actuated via the spring-loaded pressure piston 102 which is acted upon by a medium pressure above the pressure threshold _value ps, for example 10 bar.

After the medium has been switched off, the sliding rings 36, 38 can be separated again using the Pop-Off® function.

In the exemplary embodiment illustrated in FIGS. 1-6, rotor-side end faces 116 of the pressure pistons 102 apply force directly to the slide ring carrier 34, or more precisely directly to the flange 46 of the slide ring carrier 34, with the second axial force component K2. The second axial force component K2, which is caused by the clamping device 100, as well as the first axial force component, which is caused by the load ratio B, are each proportional to the applied medium pressure.

Referring to the exemplary embodiment illustrated in FIGS. 7-12, the tensioning device 100 can also have a force distributor ring 122, on which the pressure pistons 102 exert the second axial force component K2. When the pressure threshold value ps is exceeded, the end faces 116 of the pressure pistons 102 come into contact with an outer ring region 124 of the force distribution ring 122 in order to apply the second axial force component K2 to the force distribution ring 122 .

The force distribution ring 122 has an annular force-distributing ring projection 126 facing the mechanical seal 30 and which is in contact with the flange 46 when the tensioning device 100 is activated. The force distribution ring 122 thus transmits the second axial force component exerted by the pressure piston 102 to the slide ring carrier 34 or its flange 46. This allows the second axial force component to be transmitted evenly around the axis of rotation X to the slide ring carrier 34 or to the floating slide ring 38. without generating unwanted tilting moments. In addition, the application of force to the slide ring carrier 34 are shifted radially inwards via the annular projection 126 in relation to the radial position of the pressure piston 102 . As a result, the deformation of the slide ring carrier 34 can be reduced or prevented.

The force distributor ring 122 is mounted so that it can move axially in the stationary housing part 12 , in particular so that it can move axially relative to the slide ring carrier 34 and can move axially with respect to the pressure piston 102 . The force distribution ring 122 surrounds the slide ring carrier 34, for example, in a ring-shaped coaxial manner.

In the operating state for compressed air operation (FIGS. 8 and 11) there is in particular no contact between the force distribution ring 122 and the slide ring arrangement 32 . In the operating state shown in Fig. 9 and 12 when pressure is applied with a compressible medium above the pressure threshold value ps, the pressure pistons 102 press with a resultant force caused by the medium pressure on the pressure pistons 102 via the force distributor ring 122 on the slide ring arrangement 32. The second The axial force component K2 is also proportional to the medium pressure

Referring to the exemplary embodiment illustrated in FIGS. 13-18, the pressure pistons 102 can each have a closing force activation spring 132 which is arranged on the end face of the pressure pistons 102 facing the mechanical seal 30 . For example, smaller closing force activation springs 132 are let into end bores 134 of the pressure piston 102 .

As long as the medium pressure remains below the pressure threshold value ps, the clamping device 100 is not active and the closing force activation springs 132 do not exert any force on the flange 46 of the slide ring carrier 34 . When the medium pressure in the main media channel 20 and the pressure chamber 108 has exceeded the pressure threshold value ps to a sufficient extent, the pressure pistons 102 have moved against the spring force of the springs 106 axially in the direction of the mechanical seal 30 and the closing force activation spring exerts the second axial force component via the sliding ring carrier 34 , in the present example via the flange 46 onto the floating seal ring 36 . In this exemplary embodiment, the pressure pistons 102 strike against a stop 136 when the pressure threshold value ps is sufficiently exceeded, and the second axial force component K2 is then exerted on the slide ring carrier 34 exclusively by the closing force activation springs 132 . As a result, the second axial force component K2 does not continue to increase, even if the medium pressure in the main medium channel 20 continues to increase. As soon as the pressure threshold value ps is exceeded to a sufficient extent, the second axial force component remains constant, independent of the pressure, caused by the constant spring tension of the closing force activation springs 132 Pressure piston 102 acts, the closing force activation springs 132 thus exert a constant pressure-independent second axial force component K2 on the sliding ring arrangement 32. As with the exemplary embodiments in FIGS. 1-12, the pressure pistons 102 are accommodated in the stationary housing part 12 by means of the opening pressure springs 106. In contrast to the exemplary embodiments in FIGS. 1-12, however, the stroke of the pressure pistons 102 in the exemplary embodiment illustrated in FIGS. 13-18 is limited by the stop 136 and can also be extended to a maximum of the stop when pressure is applied with pressures far above the pressure threshold value ps 136 extend within the stationary housing part 12. When the stop 136 is reached, the closing force activation springs 132 act simultaneously with a constant force on the slide ring arrangement 32. The spring force of the closing force activation springs 132 is, for example, 5 N per spring. As in the other exemplary embodiments, one or more pressure pistons 102, for example two to six, preferably two to four pressure pistons 102, are possible in terms of space. For example, three or four pressure pistons 102, optionally with closing force activation springs 132, can be arranged in a ring around the slide ring carrier 34.

In the non-activated state shown in FIGS. 14 and 17 below the pressure threshold value ps, for example in compressed air operation, there is no contact between the closing force activation springs 132 and the flange 46.

In summary, the rotary union 10 therefore preferably has at least three operating states as follows:

1. When there is no pressure, the rotary union 10 defines a fully open state of the mechanical seal 30 (dry-running operating state). In the fully open dry-running operating state, the two sliding rings 36, 38 are spaced apart by a sufficiently large gap 39 so that the rotary leadthrough 10 can rotate dry-running without medium, without wear occurring on the sliding rings 36, 38.

2. When pressurized with a medium pressure below the pressure threshold value ps, the rotary union defines an operating state for operation with a compressible medium (compressed gas operating state). In this compressed gas operating state, the mechanical seal is only minimally open, just to allow controlled (air) leakage. The sealing gap 40, which allows controlled (air) leakage, is so small that it cannot be seen in the corresponding FIGS. 2, 5, 8, 11, 14, 17. In the compressed gas operating state for compressible media, the tensioning device 100 is not activated. Only the first axial force component K1 acts on the mechanical seal 30.

3. When pressure is applied with a medium pressure above the pressure threshold value ps, the rotary union defines an operating state for compressible media under a high medium pressure (liquid medium operating state). In the liquid medium operating state shown in FIGS. 3, 6, 9, 12, 15, 18, the mechanical seal is closed and the clamping device 100 is activated. Accordingly, in the liquid medium operating state, the first axial force component acts based on the load ratio B and, in addition, the second axial force component, caused by the activated clamping device 100, added together as a common closing force on the mechanical seal 30. This ensures adequate tightness even for operation with highly viscous media such as cutting oil or hydraulic oil can be achieved at high medium pressure. When operating with cooling lubricant that would be

Activation of the clamping device 100 is probably not absolutely necessary due to the lower viscosity, but it is not harmful either.

Therefore, with the clamping device 100 activated exclusively by the applied medium pressure, a targeted increase in closing force can be effected. The closing force amplification is brought about by the medium pressure within the rotary union 10 exceeding the pressure threshold value ps and the clamping device 100 being activated in response to the pressure threshold value ps being exceeded, as a result of which the second axial force component K2 on the mechanical seal 30 is activated. In the compressed gas operating state, there is a certain air leakage rate at the mechanical seal 30, e.g. In addition, the present rotary leadthrough 10 has excellent dry-running properties, since excessive heating of the slide rings 36, 38 can be avoided in dry running. The rotary feedthrough can therefore be operated at high speeds without any pressure in dry running or, in particular, with compressed air in a permissible pressure range of e.g. up to 10 bar.

If there is no pressure at all in the main media channel 20, the clamping device 100 is not activated and the secondary seal 60 can pull back the floating slide ring 36 by means of the so-called Pop-off® effect, so that there is no contact between the slide ring sealing surfaces 36a, 38a, but rather a sufficiently large gap 39 between these exists, and an unlimited dry run can also take place. This is because when the face seal 30 closes, the U-cup ring 64 may deform somewhat. In the depressurized position, the recovery assists in the opening of the mechanical seal 30. However, the present invention can also be equipped with a different secondary seal 60

In summary, the activation of the clamping device or the closing force boosting device 100 is controlled or triggered in response to the level of the medium pressure present in the main medium channel 20 . If the pressure is low, the clamping device or the closing force boosting device is not activated and if the pressure is higher, the clamping device or the closing force boosting device switches on, ie it is automatically activated under hydraulic control. As a result, in particular, a single main media channel is sufficient, into which all desired media can alternatively be introduced one after the other. The activation and/or deactivation of the tensioning device or power booster device is therefore carried out purely mechanically/physically by the level of the medium pressure of the respectively introduced medium, i.e. by increasing the pressure above the pressure threshold value ps or reducing the pressure below the pressure threshold value ps, in particular by depressurizing.

By increasing the closing force when the clamping device 100 is activated, a high degree of tightness of the mechanical seal 30 can be achieved when using cooling lubricant or cutting oil or hydraulic oil (liquid medium operating condition) and in compressed gas operation (compressed gas operating condition), e.g. with compressed air, a relatively low air leakage rate and good dry-running properties (dry-running operating condition), in particular with Pop-Off® function and high stability can be brought into harmony with each other. Furthermore, when operating with cooling lubricant, a high pressure, e.g. in particular greater than 90 bar, can be operated and the leakage rate nevertheless remains in an acceptable range, or the mechanical face seal 30 is essentially leak-free. The exemplary embodiments can, for example, be operated with the liquid media KSS or cutting oil, for example up to 140 bar or even up to 210 bar or more, as well as with compressed air up to 10 bar and with MQL up to 10 bar.

The air leakage or a slight remaining (switching) leakage of cooling lubricant or cutting oil or hydraulic oil can be discharged via a leakage port 91 . A leakage connection coupling can be connected to the leakage port 91 in order to discharge leakage liquid or the controlled air leakage from a leakage space 94 outside the mechanical seal 30 .

Referring to FIG. 20, the rotating union 10 according to the embodiments in FIGS. 1-18 is supplied with the desired fluid media by an external media distribution network 400. For compressed air operation, a compressed air source 402 is connected to an external distributor 410 via a control valve 404 and a compressed air supply line 408 . For operation with cutting oil, hydraulic oil or KSS, a tank 412 as a media reservoir for cutting oil, hydraulic oil or KSS as a liquid medium is connected via a pump 414 to a motor 416 and an external liquid medium pressure supply line 418 to the external distributor 410. The pump 414 generates the desired medium pressure P1 for the cutting oil, hydraulic oil or KSS, which can be up to 210 bar, for example. To prevent excess pressure, the fluid pressure is limited by a pressure relief valve 422 which feeds back into tank 412. When the liquid medium is switched off, the residual pressure of the liquid medium can be released again into the tank 412 via a return line 424 and a filter 426 with a parallel check valve 428 in order to depressurize the main media channel 20 .

In the present examples, the external distributor 410 is designed as a three-way valve (compressed air, liquid, return) and forms a media selection distributor in order to select the respectively desired medium. A pressure line leads from the distributor 410 as a common connection line 430 for all media to the common connection port 22 in order to introduce all media via the same connection port 22 into the same media main channel 20 alternatively in succession under pressure. In summary, a reliable rotary feedthrough 10 suitable for all media can be provided, into which both compressible media, e.g. compressed air or MQL/MQL, and incompressible media such as cooling lubricant (KSS), cutting oil or hydraulic oil can be successively introduced under pressure into one and the same main media channel 20. A high level of reliability and variability for operation with all different media is guaranteed.

It is obvious to the person skilled in the art that the embodiments described above are to be understood as examples and that the invention is not limited to these, but can be varied in many ways without departing from the scope of protection of the claims. Spatially orienting terms such as front or rear are not to be understood absolutely in space, but serve to designate the relative relationship of the components, with “front” denoting the rotor side and “rear” or “back” denoting the axial stator side opposite the rotor. Furthermore, it is evident that the features, regardless of whether they are disclosed in the description, the claims, the figures or otherwise, also individually define essential parts of the invention and are hereby to be considered individually disclosed, even if they are described together with other features are. In order to avoid unnecessary repetition, all features that are described in connection with one of the exemplary embodiments also apply as disclosed in connection with every other exemplary embodiment, unless explicitly stated otherwise.

Claims

Patent Claims:

1. Rotary feedthrough (10) suitable for multimedia for transferring fluid media from a stationary machine part into a rotating machine part (18), particularly suitable both for compressible media and for incompressible media with different viscosities, comprising: a stationary housing part (12) for installation in the stationary machine part and with a main media channel (20) into which fluid media can be introduced under pressure, a rotor (16) for connection to the rotating machine part (18) and with a rotor fluid channel (17) which is connected to the main media channel (20) of the stationary housing part (12), a mechanical seal (30) between the stationary housing part (12) and the rotor (16), the mechanical seal (30) having a rotor slip ring (38) rotating with the rotor (16) and a stator slip ring (36), wherein the stator slip ring (36) or the rotor slip ring (38) on an axially movable slip ring carrier (34) bef is established, as a result of which an axially movable slide ring arrangement (32) is formed, with the medium pressure in the rotary feedthrough (10) exerting a first axial force component (K1) on the axially movable slide ring arrangement (32), which acts in a closing manner on the slide ring seal (30), and a tensioning device (100) acting on the axially movable slide ring arrangement (32), which is activated by the medium pressure in the rotary union (10) when the medium pressure in the rotary union (10) exceeds a predefined pressure threshold value (ps), and the activated State exerts an additional second axial force component (K2) on the slide ring assembly (32), which affects the closing force of the mechanical seal (30).

2. Rotary union (10) according to claim 1, wherein the mechanical seal (30) defines a load ratio B = FH / F, where FH is the surface of the slide ring arrangement (32) that is hydraulically or pneumatically loaded by the medium pressure and F is the contact surface between the stator seal ring and the Rotor seal ring (36, 38), the first axial force component (K1) on the seal ring arrangement (32) based on the load ratio (B) increasing proportionally with the medium pressure in the rotary union (10), and the clamping device (100) being the second axial force component (K2) in addition to the load ratio (B) based first axial force component (K1) on the slip ring assembly (32) when the medium pressure exceeds the pressure threshold (ps) and the tensioning device (100) is activated.

3. Rotary union (10) according to one of the preceding claims, wherein, if the medium pressure has exceeded the predefined pressure threshold value (ps), the additional second axial force component (K2) of the clamping device (100) on the slide ring arrangement (32) is pressure-independent or pressure-dependent on the medium pressure is.

4. Rotary union (10) according to any one of the preceding claims, wherein the tensioning device (100) has one or more springs (106) which are tensioned by the medium pressure applied in the stationary housing part (12).

5. Rotary union (10) according to claim 4, wherein when a predetermined threshold value of the spring tension is exceeded, the tensioning device (100) is activated and the second axial force component (K2) exerts on the slide ring arrangement (32).

6. Rotary union (10) according to any one of the preceding claims, wherein the slide ring carrier (34) has an outer flange (46) on which the clamping device (100) engages to the additional second axial force component (K2) of the clamping device (100). to transfer the slide ring assembly (32).

7 Rotary leadthrough (10) according to one of the preceding claims, wherein the clamping device (100) has a force distribution ring (122) which distributes the additional second axial force component (K2) exerted by the clamping device (100) in a ring shape on the slide ring carrier (34).

8. Rotary union (10) according to any one of the preceding claims, wherein the tensioning device (100) has one or more spring-loaded pistons (102) which are tensioned by the medium pressure against the spring force and which the additional second axial force component (K2) of the tensioning device ( 100) on the slide ring arrangement (32) if and only if the medium pressure in the rotary union (10) exceeds the pressure threshold value (ps).

9. rotary union (10) according to claim 8, wherein the stationary housing part (12) has one or more axial bores (104), in which the or the spring-loaded piston (102) are mounted axially displaceably.

10. Rotary union (10) according to claim 9, wherein the or each spring-loaded piston (102) are sealed in the respective associated axial bore (104) by means of a sealing ring (114).

11. Rotary union (10) according to claim 9 or 10, wherein the medium pressure from the main media channel (20) acts on rear end faces (112) of the piston or pistons (102) in order to pressurize the piston or pistons (102) in the respective axial bore (104) against the spring load in the direction of the mechanical seal (30).

12. Rotary union (10) according to any one of claims 8-11, wherein the clamping device (100) has at least two or three, preferably two to six, preferably two, three or four spring-loaded pistons (102), which in particular evenly around the slide ring carrier ( 34) are arranged around in the stationary housing part (12).

13. Rotary union (10) according to any one of claims 8-12, wherein the spring-loaded piston or pistons (102) abut axially against the outer flange (46) of the slide ring carrier (34) or axially against the force distribution ring (122) in order to to transmit the second axial force component (K2) of the clamping device (100) directly to the outer flange (46) or directly to the force distribution ring (122).

14. Rotary union (10) according to any one of claims 8-13, wherein the stationary housing part (12) has a stop (136) for the spring-loaded piston or pistons (102), which stops the stroke of the spring-loaded piston or pistons (102) limited when the tensioning device (100) is activated, and wherein the spring-loaded piston or pistons (102) each have a closing force activation spring (132) which, when the tensioning device (100) is in the activated state, exerts a constant spring force that is independent of the media pressure on the sliding ring arrangement (32). , so that the additional second axial force component (K2) generated by the clamping device (100) is independent of the medium pressure when and as long as the clamping device (100) is activated.

15. Rotary union (10) according to one of the preceding claims, wherein the pressure threshold value (ps) is greater than or equal to the maximum permissible operating pressure of the rotary union (10) for compressed air operation and/or wherein the pressure threshold value (ps) is greater than 5 bar, preferably greater than or is equal to 10 bar.

16. Rotary feedthrough (10) according to one of the preceding claims, wherein the rotary feedthrough (10) comprises a connection port (22) for connecting a media pressure line in order to introduce all desired media, each with an associated medium-specific desired medium pressure, into the main media channel (20) and wherein the Rotary feedthrough (10) is designed so that both compressible media, in particular compressed air, and incompressible media, in particular cutting oil or hydraulic oil, can be introduced under pressure into the same main media channel (20) via the same connection port (22).

17. Rotary union (10) according to claim 16, wherein the connection port (22) is an axial or a radial connection port.

18. Rotary union (10) according to any one of the preceding claims, wherein the load ratio (B) of the mechanical seal (30) has a value in the range from about 0.40 to 0.65, preferably in the range from about 0.45 to 0.60, preferably in the range of about 0.47 to 0.60, preferably in the range of about 0.50 to about 0.57.

19. Rotary union (10) according to one of the preceding claims, wherein the sliding ring carrier (34) is sealed by means of a secondary seal (60) in the stationary housing part (12) and is mounted so as to be axially displaceable, in particular wherein the secondary seal (60) has an elastomer ring (64) with a U-shaped cross section.

20. Method for operating a multimedia-capable rotary union (10), in particular according to one of the preceding claims, wherein an external compressed gas source (402) is connected via an external compressed gas supply line (408) and an external distributor (410) to a connection port (22) of the rotary union (10 ) is connected, with an external media reservoir (412) with a liquid medium, in particular cutting oil or hydraulic oil with a viscosity of greater than or equal to 6 mm ² /s or cooling lubricant, via an external liquid medium pressure supply line (418) and the external distributor (410). is connected to the same connection port (22) of the rotary union (10), wherein in a compressed gas operating state in a first time interval compressed gas at a lower pressure than the liquid medium, in particular at a pressure of less than or equal to 10 bar, is introduced into the main media channel (20), with the clamping device (10 0) is not activated and the rotary union (100) rotates with the compressed gas and with a closing force on the mechanical seal (30) which is defined by a pressure-dependent first axial force component, and the compressed gas is later switched off again, with the liquid medium operating state in a second time interval via the liquid medium pressure supply line (418) and the same connection port (22) the liquid medium, in particular the cutting oil or hydraulic oil with a viscosity of greater than or equal to 6 mm ² /s or the cooling lubricant, with a higher pressure than the compressed gas, in particular with a pressure greater than 10 bar, is introduced into the main media channel (20), the tensioning device (100) being activated by the liquid pressure and the rotary union (10) rotating with the liquid medium and with an added closing force on the mechanical seal (30). , where the added closing force consists of the first axial force component (K1) and a pressure-dependent or pressure-independent additional second axial force component (K2), the pressure-dependent first axial force component (K1) being determined by the load ratio (B) and the pressure-dependent or pressure-independent additional second axial force component (K2) being determined by a is effected by the medium pressure of the liquid medium hydraulically activated tensioning device (100), and wherein the liquid medium is switched off again later.

21. The method of claim 20, wherein in a dry-running operating state in a third time interval, the rotary union (10) without

The medium rotates dry-running, with the clamping device (100) not being activated and the mechanical seal (30) being held open by the secondary seal (60).