DYNAMIC SEAL AND ROTARY JOINT WITH SUCH A DYNAMIC SEAL

Description

[0001] The present invention relates to a dynamic seal for sealing at least one channel and / or chamber from an environment, wherein the channel and / or chamber carries a fluid and extends within a stationary component and a component rotating about a rotational axis. The invention particularly relates to a rotary union with such a dynamic seal, wherein the rotary union can transfer fluid from the stationary component to the rotating component or vice versa.

[0002] Dynamic seals can be divided into axial and radial seals, although axial-radial seals are also conceivable in principle, for example because the sealing gap or sealing surface to be sealed runs obliquely to the direction of rotation of the rotating component. Axial seals in particular are also referred to as mechanical seals. The present invention is applicable to any seal in which a rotating component is sealed against a stationary component in order to seal a fluid-carrying channel and / or space against the environment. In this respect, the terms mechanical seal and counter seal of a dynamic seal according to the invention encompass any components that are supported against one another in a sealing manner, one of which is stationary and the other rotates with the rotating component.

[0003] Mechanical seals, regardless of whether they seal in the radial, axial, or angular direction, are subject to wear, meaning the seal ring and / or the mating ring must be replaced from time to time. Accordingly, service intervals are provided for mechanical seals to replace the seal ring and, if necessary, the mating ring. The service intervals must be such that replacement can be carried out in a timely manner before an unacceptable leak occurs in the mechanical seal, leading to an undesired escape of the fluid from the channel or space sealed from the environment by the mechanical seal. Such a leak is particularly serious if the fluid is harmful to the surroundings or the environment, or is otherwise hazardous.

[0004] The progressive wear of a mechanical seal, or more generally of a dynamic seal, which determines the length of the necessary replacement interval, depends on the environment in which the mechanical seal operates. The fluid composition, temperature, and / or pressure have a decisive influence. Added to this are the influences of the rotating component's speed, contamination, and other boundary conditions.

[0005] With a fixed replacement interval, there is a risk of premature wear of the mechanical seal, meaning the replacement interval may be too long in some cases. In other cases where wear is minimal, the specified replacement interval may be too short, which is uneconomical.

[0006] GB 2 395 532 A therefore proposes, for example, monitoring the numerous mechanical seals provided in a power plant, alongside other components, in order to detect excessive wear and thus the risk of leaks. For this purpose, various sensors are proposed which are connected to a data acquisition and processing device and with which forces, torque or vibrations transmitted via the mechanical seal can be recorded. According to one embodiment, the stationary ring of a mechanical seal is supported in a housing via a ring provided with pins, wherein the pins are provided with a stress measuring device from which the force, torque or vibrations acting on the mechanical seal can be deduced. A further embodiment provides for the provision of the stress measuring device directly on a support ring.According to a further embodiment, the ring is supported against rotation by a linear measuring sensor, so that a corresponding support torque can be determined. Finally, according to a further embodiment, it is proposed to detect the force, torque, or vibrations acting via the mechanical seal using a position sensor, wherein the sensor detects a change in the axial direction of a spring-bearing ring against which the counter ring of the mechanical seal is supported in the axial direction.

[0007] WO 92 / 02747 A1 discloses a rotary union wherein the sliding properties of the sliding ring can be determined largely without inertia, so that incipient damage can be detected and prevented. The sealing ring is supported radially on a rotating shaft and has a radial projection that rests on a bending rod mounted in a stationary housing. The torque transmitted from the shaft to the sealing ring causes the bending rod to be elastically bent, with the bending being measured and further processed using a strain gauge in conjunction with a corresponding evaluation device. Alternatively, a piezoelectric sensor is inserted between the bending rod and an abutment. This sensor generates an electrical voltage that can be measured and used in an evaluation device to determine the torque.Additional strain gauges allow two complementary signals to be evaluated to improve measurement accuracy.

[0008] DE 10 2012 213 510 B3 discloses a seal test bench, wherein a friction element acts directly or indirectly on a force measuring device in order to determine the friction conditions in the seal.

[0009] DE 20 2009 008 088 U1 discloses a mechanical seal with a pressure-protected monitoring device for monitoring the operating condition of the mechanical seal. A distance sensor or force sensor is provided that detects the tilting of a pin positioned radially to the rotating shaft to determine the sliding condition of the mechanical seal.

[0010] WO 2008 / 089800 A1 discloses a mechanical seal with operating condition monitoring. The monitoring device comprises a force measuring device provided in the rotational force flow between a stationary component and a rotationally secured seal ring, with a force sensor, which is any suitable electrical element, for example, piezoelectric, hydraulic, or pneumatic. The force acts tangentially to the rotational axis.

[0011] Known mechanical seals with monitoring devices have the disadvantage that the monitoring device has a comparatively complex design, which is associated with comparatively high costs. Furthermore, the integration of the monitoring device into the mechanical seal or a rotary union with such a mechanical seal requires a corresponding adaptation of the component's surroundings. If the same monitoring device is to be used for rotary unions of different sizes, adaptation to the different permissible torque values ​​occurring in the mechanical seal, with significantly different torque values, requires the sensor to be replaced or a sensor to be selected with the appropriate operating range.

[0012] DE 20 2009 008 089 U1 discloses a mechanical seal with a monitoring device for monitoring an operating state of the mechanical seal, wherein the monitoring device comprises a beam with a sensor element for detecting a bending of the beam, in particular a strain gauge.

[0013] DE 20 2009 008 088 U1 discloses a mechanical seal with a monitoring device for monitoring an operating state of the mechanical seal, wherein the monitoring device comprises a sensor, a sleeve and a pin, wherein the pin is arranged in the sleeve and is firmly connected to the sleeve, and wherein the pin is freely guided through a stationary component of the mechanical seal, wherein the sensor is operatively connected to the pin in such a way that the sensor detects a local displacement of the pin, and wherein the sleeve is firmly fixed to the stationary component and a free end region of the sleeve is in contact with the stationary seal ring.

[0014] DE 10 2016 214 942 A1 discloses a lip seal and a method for determining a condition of a lip seal or a unit sealed by the lip seal, wherein a magnet and a magnetic field sensor cooperate on a sealing lip and a body part of the lip seal to determine a distance between these parts. The magnetic field sensor may comprise a Hall sensor.

[0015] The present invention is based on the object of providing an improved dynamic seal based on the prior art, which enables monitoring of the torque acting in the dynamic seal and can be implemented more cost-effectively with the least possible intervention in the environment of the dynamic seal. Preferably, not only the torque generated by the dynamic seal itself should be monitored, but also other torque variables acting between the rotating component and the stationary component, in particular a torque generated by a bearing arrangement, for example, a rolling bearing arrangement with at least one rolling bearing.It should be particularly advantageous to be able to adapt the monitoring of the dynamic seal to different permissible torques in each specific case with a particularly minimal intervention in the sensor system and without replacing a sensor or using sensors with different working ranges (detection ranges).

[0016] The object of the invention is achieved by a dynamic seal having the features of claim 1. The dependent claims specify particularly advantageous embodiments of the invention and a rotary feedthrough with a dynamic seal.

[0017] A dynamic seal according to the invention for sealing at least one channel and / or chamber extending in a stationary component and a component rotating about a rotational axis and conducting a fluid from an environment has a sliding ring that is sealingly supported against a mating ring in the direction of the rotational axis or perpendicularly or at an angle thereto. As a rule, at least one elastic element, for example a compression spring, in particular a wave spring, is provided, which presses the sliding ring or the mating ring, or both, against the other ring in the axial direction or in the direction perpendicularly or at an angle thereto, i.e. in the direction of the rotational axis or perpendicularly or at an angle thereto, in order to achieve the sealing support.

[0018] The sliding ring or the counter ring is designed as a stationary ring, while the other ring is designed as a rotating ring. The stationary ring is mounted in a stationary housing, which is supported circumferentially around the rotation axis by a torque arm.

[0019] For example, the seal ring is designed as a stationary ring. The seal ring can be provided in a cassette form, i.e., it can have a seal ring housing in which the seal ring is movably mounted in the axial direction, i.e., the direction of the rotation axis, and supported against it. The seal ring housing encloses the seal ring in the circumferential direction. For example, the seal ring housing has a front base and a peripheral edge connected to it, which encloses the seal ring in the circumferential direction.The peripheral edge can have an inwardly projecting projection, particularly in the form of a flange, which forms an axial stop for the sliding ring. A spring element, for example in the form of a compression spring, particularly a wave spring, is provided between the base and an end face of the sliding ring facing away from the axial stop. This spring element elastically applies pressure to the sliding ring in the direction of the stop. The stop then prevents the sliding ring from moving completely or too far out of the sliding ring housing.

[0020] The sliding ring can be sealed against the sliding ring housing by means of a sealing element, for example an O-ring, in particular in the radial direction.

[0021] The slide ring housing can be made of steel or sheet steel, for example.

[0022] If the sliding ring is designed in the aforementioned cassette shape and forms the stationary, i.e. non-rotating, ring, the sliding ring housing is mounted in the stationary housing.

[0023] According to the invention, the torque support comprises an arm that is elastically deformable in the circumferential direction by means of a torque acting on the torque support, via which the torque is supported. At least one Hall sensor is assigned to the arm, which detects the position of a region of the arm that can be displaced in the circumferential direction by bending.

[0024] According to the invention, the movable portion of the arm is provided with at least one permanent magnet, the position of which is detected by the Hall sensor, which is positioned opposite the permanent magnet in the direction of the rotation axis. This enables a particularly cost-effective embodiment of the invention.

[0025] According to a preferred embodiment of the invention, the arm is detachably connected to the housing or to a stationary area to which the housing is supported via the torque support. This makes it possible to select and connect an arm optimized for its bending resistance for the specific application without structurally modifying the other components of the dynamic seal or the monitoring device that detects the torque, in particular the Hall sensor, or to replace the existing arm with another arm with a different design that is better suited to the specific application.Furthermore, it is possible to provide a set of differently dimensioned arms, wherein the arms have, for example, different thicknesses and / or widths, but preferably the same connection points, and thus to select an arm from the set for the specific application without the sliding ring having to be adapted for the integration or connection of the respective arm.

[0026] According to one embodiment of the invention, a temperature sensor is provided for detecting the temperature of the arm or an area surrounding the arm, as well as a control device configured to process the measured values ​​of the temperature sensor in order to take temperature-dependent changes in the bending behavior of the arm into account when detecting the position or to compensate for the temperature changes. The temperature sensor can, for example, be integrated into the Hall sensor, wherein the Hall sensor is preferably provided with a temperature-compensating Hall sensor control device that processes the measured values ​​of the temperature sensor. This allows the Hall sensor to also be designed with temperature compensation.

[0027] According to one embodiment, the arm is supported on both sides in the circumferential direction by a fork. When the arm is connected to the housing, the fork is located in the stationary area. When the arm is connected to the stationary area, the fork is located in the housing.

[0028] By means of such a design with a fork, a displacement of the displaceable area of ​​the arm in opposite directions in the circumferential direction can be detected with the Hall sensor.

[0029] Preferably, the Hall sensor is configured to detect the extent of the displacement of the displaceable region of the arm in the circumferential direction. Detection can be performed in steps or continuously, depending on the displacement path or extent. Detection can also be performed in intervals or continuously.

[0030] According to one embodiment of the invention, at least one second Hall sensor is assigned to the at least one permanent magnet, which detects the position of the displaceable region of the arm redundantly to the first Hall sensor. One and the same magnet can be used as a sensor for both Hall sensors. An alternative embodiment provides for at least one separate permanent magnet for each Hall sensor.

[0031] According to one embodiment of the invention, the displaceable region of the arm is provided with at least two permanent magnets on two sides of the arm facing away from each other in the direction of the rotation axis, and on each of the two sides of the arm, a Hall sensor is arranged opposite the respective permanent magnet or opposite in the direction of the rotation axis.

[0032] It has proven particularly advantageous if the arm has a longitudinal arm axis extending radially to the axis of rotation and a plate shape extending along the longitudinal arm axis, with two mutually opposite, at least substantially flat sides extending along the longitudinal arm axis and two end faces connecting the flat sides and extending along the longitudinal arm axis, which are curved, in particular concavely curved. This makes it possible to achieve optimized bending behavior of the arm and the thickness of the arm, i.e. the thickness in the direction of an axis perpendicular to the flat sides, can be varied in a targeted manner in order to change the bending resistance of the arm and thus adapt it to the respective application. Of course, changes to the shape of the curved end faces and / or the width of the arm and / or the length of the arm are also possible.The length of the arm runs in the direction of the arm's longitudinal axis, the width perpendicular to this and perpendicular to the thickness direction.

[0033] A rotary feedthrough according to the invention comprises a corresponding dynamic seal, at least one fluid inlet, and at least one fluid outlet. The fluid inlet and the fluid outlet are fluidly connected to the fluid-conducting channel and / or space of the dynamic seal, one of which opens into the housing and the other into the rotating component. Thus, the fluid can be conducted either via the fluid inlet in the housing and the fluid outlet into the rotating component or a rotating component connected thereto, or from a fluid inlet in the rotating component to a fluid outlet from the housing.

[0034] The embodiment according to the invention also enables particularly easy retrofitting of existing dynamic seals, which have a torque support of the housing via an elastically bendable arm, with a torque sensor to monitor the dynamic seal g. Here, only the arm needs to be replaced with one with a movable section, the position of which can be detected with a Hall sensor, and a corresponding Hall sensor needs to be provided.

[0035] The solution according to the invention avoids friction or other variables influencing the displacement of the displaceable area of ​​the arm in the monitoring section, so that a very precise measurement of the support torque of the dynamic seal is possible.

[0036] Redundant detection of the position of the movable section is particularly easy. For this purpose, for example, two Hall sensors can be positioned one above the other in the direction of the rotation axis and positioned opposite at least one common magnet on the movable section of the arm in the direction of the rotation axis.

[0037] With the dynamic seal according to the invention with integrated monitoring function of the torque transmitted from the stationary ring to the stationary housing, not only the dynamic seal itself can be monitored, but also, for example, the bearing or at least one bearing with which the rotating component is mounted in the stationary component. Thus, the total torque transmitted via the torque support can include both a torque transmitted in the at least one bearing and a torque transmitted between the slide ring and the counter ring. The two torque components can add up, and the position of the area of ​​the arm that can be displaced by bending depends on the torques transmitted in the bearing and between the slide ring and the counter ring. Since bearing damage in particular leads to a large increase in torque, such bearing damage is reliably detected.For this joint monitoring, it is only necessary that the bearing torque and the torque acting between the sliding ring and the counter ring are transferred jointly via the torque support to a stationary area, where the housing is supported via the torque support. Preferably, both torque components are transferred via the shared stationary housing in which the stationary ring is mounted; the ring can be formed by the stationary housing itself.

[0038] According to a preferred embodiment of the invention, the Hall sensor is designed as an at least two-dimensional Hall sensor (2D Hall sensor). In such a two-dimensional Hall sensor, two Hall elements or two Hall plates are perpendicular to one another and are arranged, in particular, point-symmetrically around a center point. This allows a magnetic field to be detected in two mutually perpendicular directions, so that both magnetic fields are changed depending on the position of the region of the arm of the torque support that can be displaced by bending in the circumferential direction. Thus, instead of detecting the absolute magnitude of a magnetic field changed by the displacement, the ratio of the two magnitudes of the detected magnetic fields or a magnetic field vector generated from this by superimposing the two magnetic fields can be used to determine the extent of displacement of the displaceable region of the arm.This has the advantage that a fluctuating absolute magnitude of the magnetic field due to environmental conditions, such as contamination, does not distort the position detection of the arm's movable area. Of course, a 3D Hall sensor can also be used instead of a 2D Hall sensor.

[0039] The invention will be described below using exemplary embodiments and the figures.

[0040] They show: Figure 1 shows an exemplary embodiment of a rotary union with a mechanical seal; Figure 2 shows a schematic plan view in the direction of the rotation axis of a rotary union with a mechanical seal according to the invention; Figure 3 shows a schematic representation of a redundant position detection system; Figure 4 shows an alternative embodiment of a redundant position detection system.

[0041] Although the invention is illustrated below using a mechanical seal with a sliding ring and counter ring supported against each other in the direction of the rotation axis, the dynamic seal according to the invention can be used for any support between a stationary component and a component rotating about a rotation axis.

[0042] In the Figure 1A rotary union with a fluid inlet 19 and a fluid outlet 20 is shown. The fluid outlet 20 is provided in a component 3 rotating around the rotational axis 10, and the fluid inlet 19 is provided in a stationary component 2, which here is formed by the stationary housing 6. A channel 1 is provided in the stationary component 2, here the housing 6, and the rotating component 3, through which a fluid can be guided from the stationary component 2 into the rotating component 3 (or vice versa). In principle, several separate channels with corresponding fluid inlets and outlets could also be provided.

[0043] To seal the channel 1, a mechanical seal is provided, comprising a sliding ring 4 and a counter ring 5, which together seal a sealing gap 21. For this purpose, the sliding ring 4 is elastically pressed against an axial end face of the counter ring 5 in the direction of the rotation axis 10 by means of a spring element 22.

[0044] In the embodiment shown, the sliding ring 4 is provided together with the spring element 22 in a sliding ring housing 23, which in turn is fixedly inserted into the housing 6.

[0045] The component 3 rotating around the rotation axis 10 is mounted in the housing 6 via bearings, for example rolling bearings 24.

[0046] Because the sliding ring 4 is elastically pressed against the counter ring 5, a torque or support torque is generated, which is transmitted from the sliding ring 4 via the sliding ring housing 23 to the housing 6. The housing 6 is in turn supported by a torque support 7 on a stationary area 12, wherein the torque support 7 has an elastically bendable arm 8, which is supported on both sides in a fork 16 of the housing 6 in the circumferential direction to the rotation axis 10. This torque support 7 with the arm 8 and the fork 16 is also known in particular from Figure 2 recognizable.

[0047] A permanent magnet 11 is provided in a circumferentially displaceable region of the arm 8, which faces the Hall sensor 9 in the direction of the rotation axis 10. The Hall sensor 9 is connected to a suitable evaluation device 25.

[0048] Thus, with the evaluation device 25 and the Hall sensor 9, a displacement of the movable area of ​​the arm 8 can be detected and evaluated and from this, conclusions can be drawn about the torque that is transmitted from the counter ring 5 to the sliding ring 4 and generates a corresponding support torque via the sliding ring housing 23 and the housing 6, which is supported by the torque support 7 with more or less strong elastic deformation of the arm 8.

[0049] Preferably, the Hall sensor 9 is provided with a temperature sensor 13, the measured values ​​of which are used in a control device 14, which may be part of the evaluation device 25, to compensate for a temperature change that alters the bending behavior of the arm 8. The Hall sensor 13 may also include a Hall sensor control device 15, which performs temperature compensation of the measured values ​​of the Hall sensor 13.

[0050] From the Figure 2 Advantageous features of the arm 8 can be seen. The arm 8 can have a longitudinal arm axis 18 extending radially to the rotation axis 10, wherein one end of the arm 8 in the direction of the longitudinal arm axis 18 forms the displaceable area of ​​the arm 8 and the opposite end is fixedly connected, here to the stationary support area 12. The arm has two essentially flat sides 8.1, 8.2, see also the Figure 1, as well as two connecting curved, here concavely curved, end faces 8.3 and 8.4. This design makes it particularly easy to adjust the desired bending behavior of the arm for individual cases, for example by changing the curvature of the end faces 8.3 and 8.4 or by changing the thickness of the arm 8, i.e., the distance between the flat sides 8.1 and 8.2.

[0051] In the embodiment shown, the arm has a widened foot part 8.5, which is provided at the end facing away from the displaceable area and has holes 26 for connecting the arm.

[0052] In the Figure 3 An arm 8 is schematically shown, which carries a permanent magnet 11.1 and 11.2 on two opposite sides, here the two flat sides 8.1 and 8.2, each of which is opposite a Hall sensor 9, 17. This allows redundant detection of the displaceable range of the arm to be achieved.

[0053] In the embodiment according to the Figure 4 Two Hall sensors 9, 17 are positioned one behind the other opposite a permanent magnet 11 in order to achieve redundancy. List of reference symbols

[0054] 1 Channel 2 Stationary component 3 Rotating component 4 Slide ring 5 Counter ring 6 Housing 7 Torque support 8 Arm 8.1, 8.2 Flat side 8.3, 8.4 Front end 8.5 Base 9 Hall sensor 10 Rotation axis 11 Permanent magnet 11.1, 11.2 Permanent magnet 12 Stationary area 13 Hall sensor 14 Control device 15 Hall sensor control device 16 Fork 17 Second Hall sensor 18 Arm longitudinal axis 19 Fluid inlet 20 Fluid outlet 21 Sealing gap 22 Spring element 23 Slide ring housing 24 Rolling bearing 25 Evaluation device 26 Bore

Claims

1. Dynamic seal for sealing at least one channel (1) and / or space with respect to an environment, said channel or space extending in a stationary component (2) and a component (3) rotating about an axis of rotation (10) and conducting a fluid; 1.1 having a seal ring (4) and a mating ring (5) which are supported in a sealing manner against one another in the direction of the axis of rotation (10) or perpendicularly or at an angle thereto and of which one is designed as a ring held in a stationary manner and the other as a ring rotating with the rotating component (3), and 1.2 the ring held in a stationary manner is mounted in a stationary housing (6) which is supported in the circumferential direction about the axis of rotation (10) via a torque support (7); wherein 1.3 the torque support (7) has an arm (8) which can be bent elastically in the peripheral direction by means of a torque acting on the torque support (7) and via which the torque is supported; characterized in that 1.4 the arm (8) is assigned at least one Hall sensor (9) which detects the position of a region of the arm (8) that can be displaced in the peripheral direction by the bending; wherein the displaceable region of the arm (8) is provided with at least one permanent magnet (11), the position of which is detected by the Hall sensor (9) which is located opposite the permanent magnet (11) in the direction of the axis of rotation (10).

2. Dynamic seal according to claim 1, characterized in that the arm (8) is detachably connected to the housing (6) or to a stationary region (12) on which the housing (6) is supported via the torque support (7).

3. Dynamic seal according to one of claims 1 or 2, characterized in that a temperature sensor (13) is provided for sensing the temperature of the arm (8) or a vicinity of the arm (8), and a control device (14) is provided which is set up to process the measured values of the temperature sensor (13) in order to take into account or to compensate for temperature-dependent changes in the bending behavior of the arm (8) during the position sensing.

4. Dynamic seal according to claim 3, characterized in that the temperature sensor (13) is integrated into the Hall sensor (9), wherein the Hall sensor (9) is provided in particular with a temperature-compensating Hall sensor control device (15) which processes the measured values of the temperature sensor (13).

5. Dynamic seal according to one of claims 1 to 4, characterized in that the Hall sensor (9) is set up to detect an amount of displacement of the displaceable region of the arm (8) in the circumferential direction.

6. Dynamic seal according to one of claims 1 to 5, characterized in that the arm (8) is supported in the circumferential direction on both sides in a fork (16).

7. Dynamic seal according to claim 6, characterized in that the Hall sensor (9) is set up to detect a displacement of the displaceable region of the arm (8) in opposite directions in the circumferential direction.

8. Dynamic seal according to one of claims 1 to 7, characterized in that the at least one permanent magnet (11) is assigned at least one second Hall sensor (17) which detects the position of the displaceable region of the arm (8) redundantly with respect to the first Hall sensor (9).

9. Dynamic seal according to claim 8, characterized in that the displaceable region of the arm (8) is provided with at least two permanent magnets (11.1, 11.2) on two sides of the arm (8) facing away from each other in the direction of the axis of rotation (10), and at least one Hall sensor (9, 17) is arranged on each of the two sides of the arm (8) opposite the respective permanent magnet (11.1, 11.2).

10. Dynamic seal according to one of claims 1 to 9, characterized in that the arm (8) has an arm longitudinal axis (18) extending radially to the axis of rotation (10) and a plate shape extending along the arm longitudinal axis (18), having at least substantially planar sides (8.1, 8.2) facing away from one another and extending along the arm longitudinal axis (18) and two end sides (8.3, 8.4) which connect the planar sides (8.1, 8.2), extend along the arm longitudinal axis (18) and are curved, in particular concavely curved.

11. Dynamic seal according to one of claims 1 to 10, characterized in that the seal is designed as a face seal, wherein the seal ring (4) and the mating ring (5) are supported in a sealing manner against each other in the direction of the axis of rotation (10).

12. Rotary feedthrough having a dynamic seal according to one of claims 1 to 11, at least one fluid inlet (19) and at least one fluid outlet (20), which are connected in a fluid-conducting manner to the channel (1) and / or space carrying a fluid and of which one opens into the housing (6) and the other opens into the rotating component (3).