Device for forming a sliding bearing or a slip-ring seal having integrated temperature measurement

Abstract

The invention relates to a device for forming a sliding bearing or a slip-ring seal, comprising at least two components which move relative to one another, wherein a first component (10) is a stationary component and a second component can be moved relative to the first component, wherein the first component comprises a slide surface (13) which faces the moving component, characterized in that at least one measuring sensor of at least one temperature sensor is at least partially embedded in the first component for the temperature-based monitoring of the state of the device.

Description

[0001] Description

[0002] Device for forming a plain bearing or a mechanical seal with integrated temperature measurement

[0003] The invention relates to a device for forming a plain bearing or a mechanical seal with integrated temperature measurement, wherein the device has at least two components movable relative to one another, wherein a first component is stationary and a second component is movable relative to the first component, and wherein the first component has a sliding surface facing the movable component.

[0004] Mechanical seals or plain bearings are used in rotating machinery, such as compressors, pumps, and motors, to seal and support the rotating shaft of the machinery. The structure of a plain bearing and a mechanical seal is similar. Two components rotating relative to one another form the basis, with a first component being stationary on the machine, while the rotating component is seated on the shaft of the machinery and rotates relative to the stationary component. Associated sliding surfaces slide against one another. A fluid can be provided between the sliding surfaces to cool and lubricate the bearing or seal. In the case of a mechanical seal, the stationary component is referred to as the counter ring.

[0005] Due to the relative sliding movement, wear occurs on both components during operation, which can lead to functional impairment or even complete malfunction. Against this background, it is already known that the condition of the bearing or seal should be continuously monitored in order to detect and signal an impending bearing or seal defect at an early stage. For example, it is already known that the temperature of the seal or bearing components can be recorded and monitored. Of particular importance here is the temperature development in the immediate area of ​​the sliding surfaces, i.e. in the area of ​​the seal or bearing gap. Since a direct measuring point in the area of ​​the sliding surface is not possible for functional reasons, the temperature sensors have so far been attached to the back of the mating ring in order to measure the surface temperature of the back of the mating ring.

[0006] Depending on the material thickness of the counter ring and characteristic material properties such as thermal conductivity and heat capacity, only partially accurate temperature measurement is possible. Furthermore, transient temperature profiles cannot be recorded or evaluated.

[0007] The object of the present invention is therefore to optimize the previously known measuring method in order to enable better monitoring of the plain bearing or the mechanical seal.

[0008] According to the invention, a device is proposed which comprises a known plain bearing or known mechanical seal and has been modified for temperature measurement. It is proposed that at least one measuring sensor of a temperature sensor for temperature-based condition monitoring of the device is not installed on a surface of the stationary bearing or seal component, but instead is embedded in the stationary component. By embedding the measuring sensor, the measuring point can be brought closer to the relevant sliding surface of the stationary component, so that the temperature present on the sliding surface of the bearing or seal can be measured much more accurately. In addition, rapid temperature changes, in particular transient jumps in the area of ​​the sliding surface, can be better detected and evaluated.Overall, the characteristic material properties of the component have less influence on the measurement result due to the closer positioning of the sensor to the sliding surface.

[0009] According to an advantageous embodiment, the device is a mechanical seal, and the first component is the counter ring of the mechanical seal. It is also conceivable for the device to be a plain bearing, and the first component to correspond to a bearing or other stationary bearing component.

[0010] Advantageously, the at least one sensor of the at least one temperature sensor is inserted into the volume of the first component from a counter surface of the first component opposite the sliding surface of the first component, i.e., there is a cavity in the component accessible from the opposite counter surface, into which the sensor can be inserted during assembly. However, it is also possible to insert the one or more temperature sensors into the component from another, non-sliding surface, for example, from a surface that is at a right angle to the sliding surface.

[0011] What is essential for the invention is that at least the measured value sensor of the at least one temperature sensor is introduced into the component volume. For the introduction of the at least one measured value sensor of the temperature sensor, one or more pocket-forming depressions can be provided on the surface of the mating surface or on another, non-sliding surface, into which the measured value sensor(s) can be plugged or inserted during installation. The measured value sensor can be a temperature-dependent resistor, for example. For the other sensor electronics, a sensor circuit board simulating a partial section of the mating surface can be provided, for example. The measured value sensors are electrically contacted with the circuit board, whereby the resistance elements are introduced into the corresponding component volumes and the circuit board rests flat on the mating surface, in particular is glued flat to the component.The board can also have one or more holes to increase the mechanical stability of the bond.

[0012] Connection pads for external contacting of the sensor can be provided on the exposed side of the circuit board. Alternatively, the integration of a sensor with a direct cable connection is also conceivable. The first component is preferably made of a material with high thermal conductivity and / or low heat capacity, so that the temperature prevailing on the sliding surface can be measured as precisely and as promptly as possible at the at least one measuring point. It is conceivable, for example, that the first component is made of a ceramic material, in particular a technical ceramic. The first component is particularly preferably made of silicon carbide, particularly preferably sintered silicon carbide.

[0013] For temperature measurement, it is advisable to arrange several temperature sensors or measuring probes offset from one another within the component. A distributed arrangement of the individual measuring probes with a constant distance from one another is preferred. If the first component is a ring, it is advisable to arrange the individual measuring probes offset from one another by an identical angular offset. A possible angular range here is between 80 degrees and 100 degrees, especially around 90 degrees.

[0014] In addition to the device according to the invention, the invention also relates to a rotating working machine, preferably a pump, in particular a centrifugal pump, particularly preferably a wet-running pump, with a device according to the present invention. Accordingly, the working machine, in particular the pump, comprises at least one shaft that is radially or axially mounted by means of a plain bearing and / or sealed by means of a mechanical seal against a wall of the working machine, in particular the housing wall. The at least one plain bearing or the at least one mechanical seal corresponds to the device according to the invention.

[0015] Furthermore, the invention also encompasses a system comprising at least one working machine according to the invention and an additional evaluation unit configured to receive the temperature measurement values ​​of the at least one temperature sensor and to monitor the condition of the plain bearing or the mechanical seal based on the received temperature measurement values. In addition to the temperature measurement values, further operating parameters of the working machine can be detected by sensors, or alternatively estimated or calculated. Further operating parameters are the current speed of the rotating shaft and / or the temperature of a fluid conveyed by the working machine or of the fluid located in the area of ​​the plain bearing or the mechanical seal. It may also be useful to detect the pressure of a fluid acting on the plain bearing or the mechanical seal and to take this pressure value into account when monitoring the bearing or the seal.

[0016] The aforementioned one or more operating parameters can be analyzed together with the temperature measurement by the evaluation unit to determine the current bearing or seal condition. Condition monitoring is preferably based on a model-based analysis of the bearing or seal.

[0017] It is particularly preferred if the evaluation unit is configured to detect and analyze transients in the measured temperature profile. The innovative integration of the sensors into the volume of the bearing or seal component creates the necessary prerequisite for the reliable recording and subsequent evaluation of these highly dynamic temperature changes or fluctuations. This system not only enables a simple evaluation of unsteady temperature profiles, but also allows the detection and evaluation of short-term, highly dynamic, transient temperature jumps.

[0018] In particular, it is useful if the evaluation unit includes at least one memory in which predefined correlation information is stored between the temperature on the sliding surface and at the measuring point of at least one sensor. The correlation depends on the material, the overall geometry of the component, and the distance and is characterized in particular by a predefined relationship. Using the correlation information, the temperature on the sliding surface can be determined.

[0019] For the invention, it is conceivable that the evaluation unit is directly integrated into the working machine, for example, in an integral machine control system of the working machine, e.g., in the pump or motor control system. Furthermore, it is conceivable that a control system of the working machine determines the at least one temperature measurement value and, if applicable, at least one other operating parameter and transmits these via a communication interface to an external evaluation unit. The outsourced evaluation and monitoring of the bearing or seal condition then takes place there. It is conceivable that the evaluation unit is implemented using a cloud-based solution.

[0020] In addition to the devices according to the invention, the present invention also relates to a method for manufacturing the device according to the invention. It is proposed to machine the prefabricated first component using a material-removing process to create one or more pocket-like depressions on a component surface or the counter surface. The corresponding sensors can then be inserted into these pocket-like depressions in a subsequent assembly step, with the one or more sensors being connected to one another via a common sensor board.

[0021] The sensor electronics board, for example, is glued to the surface of the component, while the sensors, especially the temperature-dependent resistors, are inserted into the prepared recesses. The recesses can preferably be created using laser ablation.

[0022] Further advantages and features will be explained in more detail below using figures. They show:

[0023] Fig. 1 : a plan view of the counter ring of a mechanical seal according to the invention,

[0024] Fig. 2: a sectional view along the section axis AA in Fig. 1 ,

[0025] Fig. 3: a partial view of the counter ring with mounted sensor electronics,

[0026] Fig. 4: a measurement diagram of the recorded temperature on the back of the counter ring over a period of 8 days Fig. 4a, 4b, 4c: partial sections of the measurement diagram of Fig. 4,

[0027] Fig. 5: A measurement diagram of the temperature curve with the speed of the pump drive compared,

[0028] Fig. 6: a comparison of the temperature measurements with other operating parameters of the pump,

[0029] Fig. 7: a diagram illustrating the correlation between sealing gap temperature and backside temperature and

[0030] Fig. 8: a system diagram for monitoring mechanical seals based on the temperature sensor technology according to the invention

[0031] The invention will be explained below using a mating ring for a mechanical seal, such as can be used in a pump. The mating ring is made of SSiC. A frontal annular surface of the mating ring serves as a sliding surface, facing a rotating slide ring of the seal. On the opposite annular surface, i.e., on the back of the mating ring, pocket-like grooves were created in the rear annular surface using a laser ablation process.

[0032] A representation of the reworked counter ring 10 can be seen in Figs. 1 and 2. The sliding surface of the counter ring 10 is marked with the reference numeral 13. On the opposite ring surface, i.e., the rear side 12 of the counter ring 10, two pockets 11 are provided, arranged at an angular offset of 90 degrees, which were introduced into the rear side 12 by means of a laser ablation process.

[0033] The depth of the pocket 11 is adapted to the height of the temperature sensor probe to be inserted and is between 1.5 mm and 3.5 mm; in the illustrated embodiment, the depth is approximately 2.8 mm. The height of the pocket can be between 2 mm and 3 mm, in particular approximately 2.5 mm. The width can be between 1 mm and 2 mm, in particular approximately 1.4 mm.

[0034] Fig. 3 shows a section of the counter ring with the sensor circuit board 20 glued to the back 13. The shape of the sensor circuit board 20 is matched to the ring surface of the back of the counter ring. Temperature-dependent resistor elements, e.g., PT1000 chips, are soldered to the ends 23 on the side of the circuit board facing the back 12 of the counter ring 10. The components extend vertically from the circuit board 20 into the associated pockets 11 of the counter ring 10. Via lines 22 on the back of the circuit board, the resistors are connected to the connection pads 21, which are provided for the external connection of the sensor to an external controller. In principle, a solution without a circuit board is also conceivable, in which the resistor elements are inserted directly into the pockets 11. The connection cables of the resistor cables are then led out of the pockets and serve for external connection.

[0035] The circuit board can be provided with several additional holes for better fixation of the circuit board to the mating ring. The circuit board is bonded to the mating ring using a two-component adhesive, e.g., Duralco 4703. The applied adhesive further seals the pockets. The manufactured sensor technology enables condition monitoring, detection, and interpretation of mechanical seals based on temperature measurements. The monitoring can optionally be expanded to include data fusion algorithms and a simulation model calculation of the mechanical seal system.

[0036] Due to the very good thermal conductivity and the low heat capacity of the SSiC counter ring, in addition to strong and dynamic increases in temperature (such as those that occur in the case of classic dry running), unsteady states of the mechanical seal system can be detected. Figs. 4, 4a, 4b and 4c show a continuous operation measurement of a mechanical seal of a pump at a water medium temperature of 80°C. Clearly visible are unsteady and fluctuating temperature phases, which are shown in an enlarged view in Figs. 4a, 4b and 4c. The time constants and characteristics are different here, i.e. Figs. 4a, 4b and 4c depict different events, each of which represents an individual condition class of the mechanical seal.

[0037] In addition to the temperature transient, Fig. 5 also shows the speed of the test bench with a speed sensor, i.e., the rotational speed of the mechanical seal. In practice, this speed would correspond to the pump speed. Clearly visible is the temporary decrease in speed with a simultaneous increase in the temperature of the mechanical seal, which can be explained by an increased frictional torque.

[0038] To evaluate and classify the events described above (Figs. 4a, 4b, 4c), simulation techniques can be usefully combined with sensor technology. Figs. 6 and 7 show the simulation results of an analysis of the sealing gap temperature and the back surface temperature of the stationary counter ring. The correlation of the corresponding temperatures depending on the pressure acting on the mechanical seal is clearly visible.

[0039] Fig. 8 also shows a possible system configuration for monitoring a mechanical seal in a centrifugal pump. In the centrifugal pump 30, the temperature TGLRD of the counter ring 10 is detected using the device according to the invention. In addition to the temperature measurements, the pressure PGLRD acting on the mechanical seal and the current temperature TMedium of the pumped medium are also detected by sensors.

[0040] The recorded parameters are communicated to an evaluation electronics unit 40, which determines the condition of the mechanical seal based on the received operating parameters, particularly by evaluating transient temperature changes. If the electronics detect relevant events that indicate a critical condition of the mechanical seal, a signal can be transmitted to a pump controller 50, which intervenes in the pump's operation. At the same time, the evaluation unit can transmit its analysis results to a remote service portal 60 to organize higher-level monitoring of a pump fleet. As an alternative to the decentralized solution with an evaluation unit located close to the pump, the evaluation unit could also be integrated into the service portal 60. In this case, a pump controller transmits the measurement parameters TGLRD, PGLRD, and TMedium to the service portal 60 for evaluation.The service portal 60, which can be cloud-based, can also be connected to an external portal 70 of the seal manufacturer for information exchange.

Claims

Patent claims Device for forming a plain bearing or a mechanical seal with integrated temperature measurement 1. Device for forming a plain bearing or a mechanical seal, comprising at least two components which are moved relative to one another, wherein a first component (10) is a stationary component and a second component is movable relative to the first component, wherein the first component has a sliding surface (13) facing the moving component, characterized in that at least one measured value sensor of at least one temperature sensor for temperature-based condition monitoring of the device is at least partially embedded in the first component.

2. Device according to claim 1, characterized in that the device is a mechanical seal and the first component corresponds to the counter ring (10) of the mechanical seal.

3. Device according to one of the preceding claims, characterized in that the at least one sensor is embedded in a counter surface (12) of the first component opposite the sliding surface (13) 4. Device according to claim 3, characterized in that the counter surface (12) has one or more recesses (11) forming pockets for the introduction of at least one measuring sensor.

5. Device according to claim 4, characterized in that a sensor board (20) simulating at least a partial section of the counter surface (12) is provided. which is applied, in particular glued, to the counter surface (12), wherein the one or more measuring sensors are inserted into the provided pockets (11) of the component (10).

6. Device according to one of the preceding claims, characterized in that the first component (10) is made of or comprises a material with high thermal conductivity and / or low thermal capacity, in particular the first component (10) is made of a ceramic material, in particular silicon carbide.

7. Device according to one of the preceding claims, characterized in that a plurality of measuring sensors are embedded in the component offset from one another, in particular with a constant distance from one another, wherein in the case of an annular component an angular offset between the measuring sensors of between 80-100 degrees, in particular of 90 degrees, is provided.

8. Rotating working machine, preferably a pump (30), in particular a centrifugal pump, with at least one device according to one of the preceding claims for supporting a shaft and / or sealing a shaft against a wall of the working machine.

9. System comprising at least one work machine according to claim 8 and an evaluation unit (40) configured to receive the measured values of the at least one temperature sensor and to monitor the condition of the plain bearing or the mechanical seal on the basis of the received temperature measured values.

10. System according to claim 9, characterized in that the evaluation unit (40) is configured to detect the condition of the plain bearing or the mechanical seal on the basis of the temperature measurement values and at least one further operating parameter of the working machine, in particular the rotational speed and / or the temperature of a fluid conveyed by the working machine and / or a pressure acting on the plain bearing or the mechanical seal. 11 . System according to one of the preceding claims 9 or 10, characterized in that the evaluation unit (40) is configured to detect and evaluate transients in the measured temperature profile.

12. System according to one of the preceding claims 9 to 11, characterized in that a previously stored correlation information between the temperature in the sealing gap or bearing gap and the temperature at the measuring point of the temperature sensor is stored in a memory of the evaluation unit (40).

13. System according to one of claims 9 to 12, characterized in that the evaluation unit is a component of the work machine (30) or is a central computer unit, in particular a cloud-based solution, which is communicatively connected to the work machine (30).

14. A method for producing a device according to one of claims 1 to 7, characterized in that one or more pocket-like depressions (11) are machined into the first component (10) by means of a material-removing method, in particular by means of laser ablation, and at least one measured value sensor of a temperature sensor is introduced into each pocket-like depression (11).

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