Rotary bushing with a sliding ring seal

Description

[0001] The present invention relates to a rotary union with a mechanical seal according to the preamble of claim 1.

[0002] Rotary unions, as pertaining to the present invention, comprise a stator and a rotor, each comprising at least one fluid channel. A fluid transfer interface is provided between the stator and the rotor, via which fluid can be transferred from the fluid channel of the stator into the fluid channel of the rotor, or from the fluid channel of the rotor into the fluid channel of the stator. The fluid thus flows from the stator into the rotor or vice versa, wherein in particular a fluid transfer interface can be provided between a plurality of fluid channels in the stator and in the rotor in order to form a supply line and a return line. More than two fluid channels in the stator, each connected to at least one fluid channel in the rotor, are also possible.

[0003] The fluid transfer interface is sealed from the environment by means of a mechanical seal. The mechanical seal is elastically preloaded in an axial direction and rests against at least one counter ring, forming a sealing surface with the counter ring. Due to the relative rotation between the mechanical seal and the counter ring, the mechanical seal is subject to wear. Due to the wear and the elastic support, an axial displacement occurs in at least part of the rotary union, i.e., in the stator and / or the rotor. In one design, only the mechanical seal moves. In other designs, as particularly related to the present invention, a radially outer region of the stator and / or the rotor, in particular the entire stator, moves. In order to be able to predict a remaining reliable operating life, it is desirable to record the extent of wear.

[0004] EP 3 698 073 B1 proposes, in addition to a position sensor for detecting the position of the sliding ring in the axial direction, a temperature sensor outside the fluid transfer interface, thus on a leakage side of the sealing surface between the sliding ring and the counter ring, facing away from the fluid channel. The temperature sensor detects the temperature of a leakage flow escaping through the sealing surface. The position sensor can be designed as a Hall sensor that works together with a magnet attached to the sliding ring. If the magnet moves in the axial direction, this movement can be detected by the Hall sensor.

[0005] DE 34 26 539 A1 discloses a method for monitoring the wear of the sealing surfaces of a mechanical face seal. For this purpose, a probe is provided radially relative to the axially movable face seal element of the seal or radially relative to a part that moves axially with the face seal element, so that a signal generated by the surface of the face seal element or part and directed radially outward can be recorded by the probe. The design of the surface of the face seal element or part is such that there is a signal change indicating the wear on the sealing surfaces when the face seal element moves axially relative to the probe. For example, the radial clearance between the probe and an opposing cylindrical surface changes when the face seal element or the component connected to it moves axially relative to the probe when seal wear occurs.This creates a change in the signal measured by the probe. Alternatively, a conductive or semiconductor insert can be used in the mechanical seal element, which generates a signal in the probe when maximum abrasion occurs. The use of an optical probe is also possible.

[0006] A system similar to the above-mentioned system is disclosed in US 5 448 924 A or EP 0 203 675 A.

[0007] The disadvantage of the aforementioned embodiments is that the probe for measuring the axial offset must be provided in the rotary union in addition to a speed sensor that is usually present anyway, and thus a correspondingly large installation space is required for the measuring devices.

[0008] WO 95 / 27213 A proposes a device for sensing a rotational movement and an axial displacement of a body with a single sensor. For this purpose, a structure that can be sensed by the sensor is applied to a rotating component. This structure represents an axial displacement of the component through a first significant change in the sensor's output signal and represents a change in the component's rotational speed about its axis of rotation through a second significant change in the sensor's output signal. The structure can have the shape of a triangular, sawtooth, or similar pattern. The sensor can be an inductive sensor or a Hall sensor. Thus, both rotational speed information and information about the component's axial position can be read from this signal.Since the pattern extends continuously across the entire circumference of the component to generate the desired signal changes, the magnitude of the signal change is comparatively small, so the sensor must be highly sensitive and positioned very close to the pattern in the radial direction. Only distances of a few tenths of a millimeter are permissible. This makes the device suitable only for rotating components, usually with a small outer diameter, that exhibit low imbalance and are not prone to wobbling around the rotational axis. Furthermore, the installation and calibration effort are comparatively complex.

[0009] The object of the present invention is to provide a rotary union with a wear-resistant sliding ring, the wear of which can be precisely determined during operation of the rotary union, wherein the rotary union does not require an axial displacement sensor in addition to a speed sensor.

[0010] The object of the invention is achieved by a rotary union having the features of claim 1. The dependent claims describe advantageous and particularly useful embodiments of the invention.

[0011] The rotary feedthrough according to the invention has a stator and a rotor, each comprising a fluid channel, wherein a fluid transfer interface is provided between the stator and the rotor, via which fluid flows from the fluid channel in the stator into the fluid channel in the rotor or vice versa. Thus, a fluid can be transferred from the stator to the rotor, for example a cooling medium or a process fluid or a process gas or the like. Several fluid channels can be provided in the stator and rotor, which are connected to one another via the fluid transfer interface, so that several fluids can be exchanged separately from one another via the fluid transfer interface between the stator and rotor.For example, a feed line and a return line are provided in the rotary union so that, in particular, a cooling medium can be transferred from the stator to the rotor, which, after carrying out its cooling function, is led back from the rotor to the stator in a heated state.

[0012] A mechanical seal comprising an abrasive seal ring is provided in the fluid transfer interface. The mechanical seal seals the fluid transfer interface from the environment, preventing fluid from escaping from the fluid channels. The seal ring rests elastically against at least one counter ring in an axial direction, forming a sealing surface with this counter ring.

[0013] In principle, the sliding ring can rotate with the rotor and be connected to the rotor in a rotationally fixed manner, or it can be held stationary by the stator and thus not rotate. According to a further embodiment, the sliding ring is freely inserted between the rotor and the stator, so that its rotation is indeterminate. This means that before the rotary union is operated, it is unknown whether and at what speed the sliding ring rotates. In particular, the sliding ring rotates only temporarily and / or at a lower speed than the rotor. The present invention is particularly suitable for such an embodiment.

[0014] According to the invention, an axial displacement detection device is provided which is configured to detect an associated axial displacement of the stator and / or the rotor in the event of wear of the sliding ring. It is not necessary for the entire rotor and / or stator to be displaced, but possibly only a part of it. The axial displacement detection device comprises a rotary encoder, in particular radially outwardly on the rotor, and a sensor which detects a position of the rotary encoder and which is radially opposite the rotary encoder. The rotary encoder has at least one discrete marking or a plurality of discrete markings arranged circumferentially at a distance from one another and one behind the other, which are arranged on a radially outer surface of the rotor.The at least one discrete marking or the plurality of discrete markings arranged at a distance from one another vary along the axial direction in their extension in the circumferential direction and / or in different axial sections of the rotor different numbers of individual discrete markings are provided one behind the other in the circumferential direction.

[0015] The at least one discrete marking thus also represents a structure that can be scanned by the sensor such that an axial displacement of the rotor, i.e. at least of the part of the rotor bearing the marking, is represented by a first significant change in an output signal of the sensor, and a change in the speed of the rotor about its axis of rotation is represented by a second significant change in the output signal of the sensor. For example, the discrete marking has the shape of a triangle, which is in particular full-surface. Preferably, the base of the triangle extends in the circumferential direction of the rotor or in the direction of rotation of the rotor, and the height extends in the axial direction. In the case of several discrete markings, a corresponding number of such triangles, in particular identical triangles, can be arranged on the rotor at a distance from one another in the circumferential direction.

[0016] Due to the inventive design with at least one discrete marking, the sensor's output signal changes particularly significantly, even if the sensor, as provided according to one embodiment of the invention, is arranged with a radial distance or radial gap from the rotary encoder in the radial direction of at least 1 or 2 mm, in particular of at least 5 mm. This allows for a certain imbalance or wobble of the rotor during operation of the rotary feedthrough, although this may well be necessary in practice.

[0017] In particular, the sensor generates an on-off signal, whereby a signal change occurs whenever a discrete marking enters the detection range of the sensor and when this discrete marking exits the detection range of the sensor again.

[0018] Other advantageous embodiments of the discrete marking include markings with steps or curves, such that the extent of the individual discrete marking changes over the circumference, in each case in the course of the marking along the axial direction.

[0019] A variation of the circumferential extent of the marking over its extension along the axial direction can also be achieved by providing a different number of individual discrete markings in different axial sections.

[0020] To facilitate installation, the position of the sensor and / or the at least one rotary encoder can be adjustable in the radial direction and / or axial direction.

[0021] According to one embodiment, the rotary encoder extends only over a portion of the circumference, in particular less than 45° or less than 10°. The remaining area of ​​the circumference is thus free of markings that are detected by the sensor. This enables a particularly flexible and cost-effective arrangement of the rotary encoder.

[0022] Preferably, the stator comprises a housing with at least one fluid inlet and / or fluid outlet, and the sensor is supported by a bracket connected to the housing. Such a bracket, provided separately from the housing, can reduce heat input from the housing, which is heated by the fluid, into the sensor. For example, the bracket comprises a sheet metal strip supporting the sensor, which is preferably adjustably connected to the housing. This reduces heat conduction from the housing to the sensor and simplifies sensor installation.

[0023] According to one embodiment, thermal insulation is provided between the console and the housing, for example in the form of an insulating layer.

[0024] The rotary encoder can preferably be formed by an angle plate connected to the rotor, which then carries or has the at least one discrete marking. The marking can thus be incorporated directly into the angle plate, formed by it, or provided in an additional component connected to the angle plate.

[0025] Connecting the encoder to the rotor using an angle plate or another intermediate component can also reduce the heat input from the rotor into the sensor area and enables particularly easy, even retrofitting, installation of the encoder. For example, the encoder can be connected to the rotor using a clamping flange. Such a clamping flange comprises, for example, a particularly slotted inner ring, which is pressed onto the rotor with an outer ring. The contact surfaces between the inner ring and outer ring can be angled to the axis of rotation, so that axial displacement of the outer ring causes the inner ring, which is preferably C-shaped, i.e., has a gap between its circumferential ends, to clamp onto the rotor.

[0026] Of course, the encoder can also be connected to the rotor in other ways, for example, as a screw flange on a rotor thread, or through another screw connection or a material-to-material connection. Other configurations are possible.

[0027] Preferably, a control device is provided which processes signals generated by the sensor as a function of the current circumferential position of the at least one marking, wherein the control device and / or the sensor generates a sequence of on-off signals which, as previously described, are each generated with the entry and exit of a marking into the detection range of the sensor.

[0028] According to one embodiment of the invention, the sliding ring forms a sealing surface on each of its two opposite end faces, i.e. axially, each with a counter ring and is rotatable in the circumferential direction relative to both counter rings. The present invention is therefore also suitable for mechanical seals whose sliding ring can only be rotated on one side relative to a counter ring. For example, the counter ring is formed by the rotor or rotates with the rotor and the sliding ring is connected to the stator, in particular connected in a rotationally fixed manner. The sliding ring can also rotate together with the rotor and the counter ring can, for example, be connected to the stator in a rotationally fixed manner or be formed by the latter. In the case of a sliding ring that seals on two sides, it can bear against a counter ring in the stator and against a counter ring in the rotor.

[0029] The invention will be described below using an exemplary embodiment and the figures.

[0030] They show: Figure 1 shows an embodiment of a rotary union according to the invention in an axial section; Figure 2 shows the rotary union from the Figure 1 in a side view with the rotating component connected to the rotor; Figure 3 an isometric view of the rotary union from the Figure 1 ; Figure 4 an alternative design of a possible rotary encoder.

[0031] In the Figure 1 A rotary union with a stator 1 and a rotor 2 is shown in an axial section. A first fluid channel 3.1 and a second fluid channel 3.2 are provided in the stator 1, one of which forms, for example, a supply line and the other a return line. A first fluid channel 4.1 and a second fluid channel 4.2 are also provided in the rotor 2, whereby their sealing against each other only consists of the Figure 2 is evident, since the representation in the Figure 1 an inner pipe section has not yet been inserted into the rotor 2. The pipe section is only indicated by the dashed line.

[0032] A fluid transfer interface 5 is provided between the stator 1 and the rotor 2, via which fluid can flow from the first fluid channel 3.1 in the stator 1 into the first fluid channel 4.1 in the rotor 2 or vice versa, and fluid can flow from the second fluid channel 3.2 in the stator 1 into the second fluid channel 4.2 in the rotor 2 or vice versa.

[0033] The fluid transfer interface 5 is sealed with a mechanical seal 6, which comprises a sliding ring 7, which, in the axial direction X, which corresponds to the axis of rotation of the rotor 2, is elastically preloaded against at least one counter ring 8, here two counter rings 8, and forms a sealing surface with this / these. The sliding ring 7 thus advantageously has two axial end faces 7.1, 7.2 at opposite axial ends, which each bear sealingly against a counter ring 8. In the event of relative rotation between the sliding ring 7 and one or both counter rings 8, wear occurs on these end faces 7.1, 7.2. In order to nevertheless enable the sliding ring 7 to bear sealingly against the counter rings 8, the rotor 2 and / or the stator 1 is adjusted in its axial position so that the wear is compensated. This adjustment, which can be achieved by elastic preload, see the Figure 1drawn elastic preload force F, the rotor 2 moves relative to the stator and / or the stator 1 relative to the rotor 2, due to an axial movement of the rotor 2 and / or the stator 1.

[0034] In the embodiment shown, one counter ring 8 is arranged in particular in a rotationally fixed manner in the stator 1 and the other counter ring 8 rotates with the rotor 2.

[0035] To detect the relative movement in the axial direction X between the stator 1 and the rotor 2 and simultaneously to measure the rotational speed of the rotor 2, a rotary encoder 9 and a sensor 10 are provided, which are arranged opposite each other in the radial direction. The sensor 10 is fixedly connected to the stator 1, here to a housing 12 of the stator 1, which forms a fluid inlet 13 into the first fluid channel 3.1 and a fluid outlet 14 from the second fluid channel 3.2.

[0036] The sensor 10 is held in its predetermined position radially outside the rotary encoder 9 by a bracket 15 connected to the housing 12, which comprises a sheet metal strip 16. The rotary encoder 9 is formed by an angle plate 17 connected to the rotor 2, which, for example, carries or forms a single discrete marking 11. A preferred embodiment of the discrete marking 11 is shown in FIGS. Figure 2 and 3 Here, the discrete marking 11 has the shape of a triangle, the base of which extends in the circumferential direction of the rotor and the height of which extends in the axial direction X. Preferably, the discrete marking 11 is simply formed by an angled end of the angle plate 17. This enables particularly cost-effective production. Thus, the rotary encoder 9 has only a single marking 11 over the circumference and extends in the circumferential direction only within the angular range of this marking 11.

[0037] Of course, according to other embodiments, a plurality of angle plates 17 or an angle plate 17 with a plurality of arms can also be provided in order to place a plurality of markings 11 opposite the sensor 10 in the radial direction, which are then arranged one behind the other at a distance from one another in the circumferential direction. Other configurations of the rotary encoder 9 are also possible, for example in the form of a collar and / or cylinder extending around the circumferential direction, on which at least one marking 11 or a plurality of markings 11 are provided accordingly.

[0038] By designing a discrete marking 11, an on-off signal is generated by the sensor 10 or a connected control device 18, even when the radial gap 19 between the sensor 10 and the rotary encoder 9 or the marking 11 is comparatively large. The axial displacement detection device is thus particularly robust and easy to calibrate, and preferably adjustable in the position of the sensor 10 and / or rotary encoder 9 in the radial direction.

[0039] In the exemplary embodiment shown, although not necessarily, the rotary encoder 9 is connected to the rotor 2 via a wedge connection 20. For this purpose, an outer ring 21 and an inner ring 22 are provided, which, in an axial section, have contact surfaces that are aligned obliquely to the axial direction X of the rotary feedthrough and bear against one another. The inner ring 22 could be formed integrally with the rotor 2, but preferably bears against a projection in the rotor 2 in the direction of the rotating component 23 connected to the rotor 2, for example a roller, so that when the outer ring 21 is pulled against the component 23 via a corresponding screw connection 24, the entire rotor 2 is attracted to the component 23 via the wedge connection 20 in order to position the rotor 2 in a desired position relative to the stator 1. If the inner ring 22 is slotted, i.e. has a C-shape, it is pulled against the rotor 2 when the outer ring 21 is tightened.

[0040] Component 23 is supplied with a fluid, for example, cooled, via the rotary union or the fluid channels 3.1, 3.2, 4.1, 4.2. In particular, component 23 is the calender roll of a paper machine.

[0041] In the Figure 4an alternative embodiment of a rotary encoder 9 is shown schematically, in which a different number of discrete markings 11 is provided in individual axial sections I, II. Nevertheless, the rotary encoder 9 can be manufactured from a simple angled sheet 17, namely in that the angled end opposite the sensor 10 (not shown here) is fork-shaped and thus a single marking 11 is formed in the axial section I, which adjoins the radial arm of the angled sheet 17, and in the region of the free end of the angled sheet 17 in the axial region II, at least two individual markings 11 spaced apart from one another in the circumferential direction are formed. Of course, a larger number of markings 11 spaced apart from one another in the circumferential direction can be provided, or even more stages and thus several axial sections with a different number of markings 11 can be provided.

[0042] In the illustrated embodiment, the position of the sensor 10 is flexibly adjustable. Thus, the sheet metal strip 16 of the bracket 15 can be adjusted in the axial direction relative to an angle 25 connected to the housing 12 of the stator 1 by loosening a screw connection and then tightening the screw connection. Furthermore, the angle 25 and / or the angle plate 17 of the rotary encoder 9 can be connected to the housing 12 or rotor 2 in a radially adjustable manner, and / or the sensor 10 can be connected to the bracket 15, in particular to the sheet metal strip 16, in a radially adjustable manner. List of reference symbols

[0043] 1Stator 2Rotor 3.1Fluid channel 3.2Fluid channel 4.1Fluid channel 4.2Fluid channel 5Fluid transfer interface 6Mechanical seal 7Seal ring 7.1End face 7.2End face 8Counter ring 9Encoder 10Sensor 11Marking 12Housing 13Fluid inlet 14Fluid outlet 15Bracket 16Sheet metal strip 17Angle plate 18Control device 19Radial gap 20Spline connection 21Outer ring 22Inner ring 23Component 24Screw connection 25Angle XAxial direction FPreload

Claims

1. Rotary feedthrough having a stator (1) and a rotor (2), which each have at least one fluid channel (3.1, 3.2, 4.1, 4.2); having a fluid transfer interface (5) between the stator (1) and the rotor (2), via which a fluid flows out of the fluid channel (3.1, 3.2) in the stator (1) into the fluid channel (4.1, 4.2) in the rotor (2) or vice versa, wherein the fluid transfer interface (5) is sealed off from the environment by means of a face seal (6) comprising an abrasive sliding ring (7), and the sliding ring (7), elastically pretensioned in an axial direction (X), rests against at least one counter-ring (8) and forms a sealing surface with the latter; characterized in that an axial displacement detection device is provided which is set up to detect, when the sliding ring (7) is worn, an associated axial displacement of the stator (1) and / or of the rotor (2), wherein the axial displacement detection device comprises a rotary encoder (9) on the rotor (2) and a sensor (10) that detects a position of the rotary encoder (9) and is radially opposite the rotary encoder (9), and the rotary encoder (9) comprises at least one discrete marking (11) or a plurality of discrete markings (11) spaced apart from one another in the circumferential direction and arranged successively on the rotor (2), and the at least one discrete marking (11) varies in its extension in the circumferential direction along the axial direction (X) and / or different numbers of individual discrete markings are provided in succession in the circumferential direction in different axial sections of the rotor (2).

2. Rotary feedthrough according to claim 1, characterized in that the position of the sensor (10) and / or of the at least one rotary encoder (9) can be adjusted in the radial direction and / or axial direction.

3. Rotary feedthrough according to one of claims 1 or 2, characterized in that the rotary encoder (9) extends only over part of the circumference, in particular less than 45° or less than 10°.

4. Rotary feedthrough according to one of claims 1 to 3, characterized in that the stator (1) comprises a housing (12) having at least one fluid inlet (13) and / or fluid outlet (14), and the sensor (10) is carried by a bracket (15) connected to the housing (12).

5. Rotary feedthrough according to claim 4, characterized in that the bracket (15) comprises a sheet-metal strip (16) which carries the sensor (10).

6. Rotary feedthrough according to one of claims 1 to 5, characterized in that the rotary encoder (9) is formed by an angled metal sheet (17) which is connected to the rotor (2).

7. Rotary feedthrough according to one of claims 1 to 6, characterized in that a control device (18) is provided which processes signals generated by the sensor (10) as a function of the current circumferential position of the at least one marking (11), wherein the control device (18) and / or the sensor (10) generates a sequence of on-off signals.

8. Rotary feedthrough according to one of claims 1 to 7, characterized in that a radial gap (19) between the rotary encoder (9) and the sensor (10) is at least 1 or 2 mm, in particular at least 5 mm.

9. Rotary feedthrough according to one of claims 1 to 8, characterized in that the sliding ring (7) forms a sealing surface with a counter-ring (8) on each of its two mutually opposing end sides (7.1, 7.2) and can be rotated in the circumferential direction with respect to the two counter-rings (8).

10. Rotary feedthrough according to one of claims 1 to 9, characterized in that the at least one discrete marking (11) has a triangular shape.