Mechanical seal device with microsystem, pump device therewith and method for its operation

Abstract

Mechanical seal device (1) with a mechanical seal (10), wherein the latter has a dry-running protection device (20), wherein the dry-running protection device (20) has at least one microsystem (21) which outputs a digital measured value (W), wherein the microsystem (21) is arranged adjacent to the mechanical seal (10) and / or on and / or in the mechanical seal (10), wherein the microsystem (21) has a power generator, wherein the power generator is an induction-based electrical generator.

Description

[0001] The invention relates to a mechanical seal device according to claim 1, a pump device therewith according to claim 12 and a method for operating the same according to claim 15.

[0002] Mechanical seals, also known as dynamic seals, seal rotating shafts against a wall, e.g., a machine housing or a pump housing. Their main components are two components that slide against each other: a sliding ring and a mating ring. Often, the sliding ring or mating ring is spring-loaded toward the other main component. One of the two rings sits rigidly in the stationary housing. The other of the two rings is secured against rotation on the rotating shaft and thus rotates with the shaft. A contact surface between the two rings forms the sealing zone.

[0003] A disadvantage of the current technology is that these mechanical seals become hot under certain operating conditions, especially when the pumps are running dry. The elastomers used are thermally overloaded, wear out, and, in the worst case, fail very quickly. When the sealing effect deteriorates, extensive repairs are necessary.

[0004] DE 10 2017 218 711 A1 discloses a mechanical seal for sealing a fluid-carrying channel and / or chamber extending within a stationary component and / or a rotating component from the environment. The seal comprises a sliding ring that is supported in an axially sealing manner against a mating ring and, to compensate for wear, is elastically supported on its end-face sealing surface or on a mating surface and movably supported in the axial direction with this sealing surface against the mating ring. The mechanical seal has a position sensor for detecting the position of the sliding ring in the axial direction. In addition, a temperature sensor is provided on a leakage side of the sealing surface facing away from the channel and / or chamber. The temperature sensor at least indirectly detects a temperature that depends on the magnitude of a leakage flow passing from the channel and / or chamber via the sealing surface.

[0005] DE 10 2017 128 566 A1 describes a sensor arrangement in a process plant.

[0006] DE 197 24 308 A1 describes a method for determining the probability of failure and / or the theoretical remaining service life of a mechanical seal, wherein the pressure of the medium, the leakage pressure, the humidity on the side of the mechanical seal facing away from the medium, the temperature of the medium and / or the temperature of elements of the mechanical seal are measured.

[0007] DE 10 2015 226 311 A1 describes a shaft seal assembly and a method for monitoring the shaft seal. The assembly comprises a rotating seal ring and a stationary seal ring. A sealing gap with a lubricating film is arranged between the seal rings. The assembly includes a sound transducer for exciting sound waves in the seal ring. A unit evaluates the signals from the sound transducer. For this purpose, the sound transducer is configured to generate and / or receive Lamb-Rayleigh waves.

[0008] The object of the invention is to create the conditions for ensuring high operational reliability and service life of a mechanical seal, while the solution should be reliable, easy to handle, compact and inexpensive.

[0009] Main features of the invention are set out in the characterizing part of claim 1 and claims 12 and 15. Embodiments are the subject of claims 2 to 11, 13, 14 and 16 as well as the description.

[0010] The invention relates to a mechanical seal device (also generally referred to as a device) with a mechanical seal and with a dry-running protection device, wherein the dry-running protection device has at least one microsystem that outputs a digital measured value, wherein the microsystem is arranged adjacent to the mechanical seal and / or on and / or in the mechanical seal, wherein the microsystem has a power generator, and wherein the power generator is an induction-based electrical generator.

[0011] Using the digital measurement value, the operating conditions of the mechanical seal can be easily recorded and evaluated, allowing the mechanical seal to be kept in non-critical operating conditions. This increases its service life. The use of a microsystem requires only a small amount of space and is also cost-effective. The fact that the microsystem incorporates a power generator creates the prerequisites for self-sufficient operation.

[0012] In a preferred embodiment, the microsystem comprises a MEMS chip. MEMS chips (microelectromechanical systems or micromachines) are tiny components that combine logic elements and / or micromechanical structures in a single chip. They can process mechanical and / or electrical information. The micromechanical structures are preferably a few millimeters in size, in particular a maximum of 5 millimeters and preferably a maximum of 3 millimeters. Thanks to their miniaturization, they can be mass-produced inexpensively. Such a MEMS chip can be arranged, for example, on a circuit board, in particular a printed circuit board.

[0013] According to an optional embodiment, the microsystem includes a temperature sensor, and the digital measured value is a temperature value. This allows for timely detection of mechanical seal overheating, which often precedes failure. This allows for early response by adjusting operating parameters to prevent temperature-related damage to the mechanical seal.

[0014] In a special variant, the temperature sensor is an optical sensor. Such a sensor can measure the temperature optically, particularly without contact to the measuring point, and in particular without contact to a measuring point on the mechanical seal. Such an optical temperature sensor could be placed in or on the rear wall of a pump, as an example of an intended installation location. From this position, the temperature of a mechanical seal arranged in or on the rear wall of the pump could be determined. Particularly preferably, the optical temperature sensor is part of a MEMS chip.

[0015] The microsystem can be assigned to a seal ring or a counter ring of the mechanical seal. Preferably, the microsystem is assigned to the static ring from the group of seal rings and counter rings. This is technically easier to implement because, firstly, cable connections are also possible, and secondly, no potential imbalances need to be compensated for. The assignment can optionally involve arranging the microsystem adjacent to the seal ring and / or on and / or in the seal ring, and optionally adjacent to the counter ring and / or on and / or in the counter ring.

[0016] In a special variant, one of the measuring points of the temperature sensor is located in the area of ​​the mechanical seal. This allows for a direct temperature measurement at the mechanical seal, and temperature changes are quickly detected without significant delay.

[0017] In another design option, the microsystem incorporates a pressure sensor, and the digital measured value is a pressure value acting on the mechanical seal. Determining a pressure can provide an early warning of impending overheating of the mechanical seal, particularly when the mechanical seal is used in pumps. Changing pressures are often accompanied by changes in the lubrication behavior of the mechanical seal. Furthermore, pressure fluctuations directly lead to temperature changes in the pumped medium, which in turn affect the mechanical seal temperature.

[0018] In another design option, the microsystem incorporates a humidity sensor, and the digital measured value is the humidity level prevailing in the area of ​​the mechanical seal. This makes it possible, for example, to anticipate impending overheating, which could occur due to insufficient lubrication. A low humidity level is an indicator of insufficient lubrication.

[0019] Furthermore, the microsystem optionally features a wired and / or wireless data interface, such as Bluetooth, for outputting the digital measured value. This allows the measured values ​​to be transmitted to an external receiver.

[0020] According to a special design, the microsystem is encapsulated within the mechanical seal. This protects it from external influences and enables reliable operation even in aggressive environments.

[0021] According to the invention, the power generator is an induction-based electric generator, with the induction preferably being achieved by relative rotation between a sliding ring and a counter ring of the mechanical seal, or alternatively between the rotating shaft and the stationary counter ring. This allows power to be generated without the need for external power sources.

[0022] Furthermore, there is the option of the microsystem being able to incorporate an energy storage device, preferably an accumulator. This allows a digital measurement value to be output, at least temporarily, even when the mechanical seal is not rotating.

[0023] Another variant provides for the microsystem to have a wired power connection. This allows for a particularly cost-effective and compact microsystem.

[0024] The invention also relates to a pump device having a pump housing in which a shaft passage is formed, having a pump shaft that rotatably projects into the shaft passage or is rotatably mounted in the shaft passage, and having a mechanical seal device as described above and below, wherein the mechanical seal is arranged in the shaft passage and sits on the pump shaft. In pumps in particular, mechanical seals are lubricated and cooled by the medium to be pumped. The changing operating conditions of the pump and the medium to be pumped therefore affect the temperature and tightness of the mechanical seal. In this respect, monitoring the mechanical seal is of increased importance, and the pump device can be protected from failures caused by damage to the mechanical seal.

[0025] Optionally, the microsystem can be configured to interact with a control unit of a drive motor of the pump shaft, in particular to control or regulate the speed of the drive motor, for example, to a maximum permissible temperature at a measuring point on the mechanical seal. The control unit can be located on or in the pump housing. Alternatively, however, the control unit can also be located at a distance from the pump housing, for example, as a central or higher-level control unit.

[0026] According to a particular embodiment, the microsystem is connected to a frequency converter of a drive motor of the pump shaft. This enables direct control of the drive motor and its speed.

[0027] For example, a special design correlates the speed of the pump shaft drive motor with the microsystem's digital measured value. This can be configured so that normal operation occurs regardless of the measured values, and emergency operation is activated at certain measured values.

[0028] Furthermore, the invention relates to a method for operating a pump device as described above and below, in which the speed of a drive motor of the pump shaft is adjusted, in particular automatically, based on the digital measured value of the microsystem. This allows the mechanical seal to be maintained in non-critical operating conditions, thus ensuring a long service life.

[0029] According to one process option, the digital measured value is a temperature value, and the drive motor speed is reduced when a limit temperature is exceeded, preferably to the limit temperature. By reducing the speed, less heat is generated at the mechanical seal due to friction. By simply reducing the speed, the pumping process can continue. This protects the pump from wear-and-tear restarts. Furthermore, operating conditions can be avoided in which every restart of the pump at normal speed would immediately lead to the limit temperature being reached again.

[0030] Further features, details, and advantages of the invention will become apparent from the wording of the claims and from the following description of exemplary embodiments with reference to the drawings. They show: Fig. 1 a partial section through a pump device with a mechanical seal device; Fig. 2 an enlargement of a section of the pump device according to Fig. 1; and Fig. 3 a counter ring of a mechanical seal with a microsystem.

[0031] Fig. 1 shows a pump device 100 with a pump housing 101 in which a shaft passage 102 is formed. A pump shaft 103 extends through the shaft passage 102 and is rotatably mounted there. The pump shaft 103 is connected on one side of the shaft passage 102 to a drive motor 105, by which the pump shaft 103 can be rotatably driven. On the other side of the shaft passage 102, the pump shaft 103 is non-rotatably connected to a pump impeller 106, which is rotatably arranged in a delivery chamber 107 of the pump housing 101. Depending on its rotations, the pump wheel 106 delivers a fluid between two openings 108, 109, namely from a suction-side inlet (first opening 108) and to a pressure-side outlet (second opening 109), each forming a flow connection that opens through the pump housing 101 into the delivery chamber 107.In this case, the impeller 106 can therefore, in particular, convey a fluid from the suction-side inlet (first opening 108) to the pressure-side outlet (second opening 109). The rotational speed of the impeller 106 depends on the drive motor 105, whose speed can be controlled by means of a frequency converter.

[0032] Such a pump device 100 can now be optionally equipped with the individually described variants of the mechanical seal device. One possible variant is described in more detail below.

[0033] The pump device 100 according to Fig. 1 also has a mechanical seal device 1, which in turn has a mechanical seal 10 arranged in the shaft passage 102. The mechanical seal 10 seals the rotatable pump shaft 103 against the pump housing 101. For this purpose, the mechanical seal 10 is seated on the pump shaft 103. This special arrangement of the mechanical seal 10 can in turn have the optional features described below. Such optional features are particularly also shown in the enlarged section according to Fig. 2.

[0034] How to do this especially in Fig. 2, the mechanical seal device 1 has a dry-running protection device 20 with a microsystem 21, which outputs a digital measured value W to an evaluation unit 28 via a data interface 25, in particular a cable line. For this purpose, the microsystem 2 can be arranged adjacent to the mechanical seal 10 and / or on and / or in the mechanical seal 10.

[0035] The microsystem 21 is designed according to the Fig. In the optional variant shown in Figure 2, the frequency converter 105 of the drive motor 105 of the pump shaft 103 is indirectly connected via the spaced-apart evaluation unit 28 (alternatively, connections to other control or monitoring devices are also possible). This makes it possible to correlate the speed of the drive motor 105 of the pump shaft 103 with the digital measured value W of the microsystem 21.

[0036] The optional cable line used here, which contains the data interface 25, also forms a wired power connection for the microsystem 21.

[0037] The microsystem 21 is arranged in the present case on a stationary counter ring 12 of the mechanical seal 10, which corresponds to a sliding ring 11 mounted in a rotationally fixed manner on the rotatable pump shaft 103.

[0038] However, particularly in the case of wireless data interfaces 25, an arrangement of the microsystem 21 on the sliding ring 11 can also be considered as an option.

[0039] A possible design of the counter ring 12 with the microsystem 21 is Fig. 3. Here, it can be seen that the microsystem 21 is arranged in a recess 13 in the counter ring 12. In particular, it does not protrude from the recess 13. The microsystem 21 has, in particular, a MEMS chip 26 on a circuit board 27. Integrated into this MEMS chip 26 of the microsystem 21 are, together or individually: - a temperature sensor 22, whose digital measured value W is a temperature value; - a pressure sensor 24, whose digital measured value W is a pressure value acting on the mechanical seal 10; - a humidity sensor 28, whose digital measured value W is a humidity value prevailing in the area of ​​the mechanical seal 10.

[0040] The MEMS chip 26 thus forms a measuring point 23 for the temperature sensor 22, the pressure sensor 24 and the humidity sensor 28 in an area of ​​the mechanical seal 10. The measured value W of the different sensors is transmitted via the data interface 25 to the separately arranged evaluation unit 28 (see also Fig. 1 and Fig. 2) issued.

[0041] Such an arrangement enables a method in which the speed of the drive motor 105 of the pump shaft 103 is adjusted based on the digital measured value W of the microsystem 21. This method may, for example, include: - a reduction in the speed of the drive motor 105 when a limit temperature is exceeded by the temperature value; - an increase in the speed of the drive motor 105 when the temperature value falls below the limit temperature; - a reduction or increase of the speed depending on the measured humidity value; and - a reduction or increase of the speed depending on the measured pressure value.

[0042] The invention is not limited to one of the embodiments described above, but can be modified in many ways.

[0043] Thus, the microsystem 21 can optionally be equipped with a wireless data interface 25 for outputting the digital measured value W instead of the wired data interface 25.

[0044] It is also possible to supply power to the microsystem 21 wirelessly. This opens up the possibility of arranging the microsystem 21 completely encapsulated within the mechanical seal 10, in particular the counter ring 12 or the slide ring 11.

[0045] For a wireless power supply, the microsystem 21 has a power generator, in particular also of micro design, which is an induction-based electrical generator. The induction is preferably caused by the relative rotation between the sliding ring 11 and the counter ring 12 of the mechanical seal 10, because this ensures that the mechanical seal 10, as a structural unit, has all the functionally necessary design features. Alternatively, the induction can also be caused between the rotating pump shaft 103 and the stationary counter ring 12.

[0046] To ensure that a measured value W is available even when the pump shaft 103 is stationary, it is advisable to equip the microsystem 21 with an energy storage device, particularly also in a micro design, such as an accumulator or an electrical capacitor. In the optional combination with the power generator, this energy storage device can be charged regularly. List of reference symbols 1 mechanical seal device 10 Mechanical seal 11 sliding ring 12 Counter ring 13 Deepening 20 Dry-running protection device 21 Microsystem 22 Temperature sensor 23 measuring point 24 pressure sensor 25 Data interface 26 MEMS chips 27 circuit board 28 Evaluation unit 29 Humidity sensor 100 pump device 101 Pump housing 102 Wave passage 103 Pump shaft 105 Drive motor 106 Pump wheel 107 Production Chamber 108 Opening or suction-side inlet 109 Opening or pressure-side outlet W digital measured value

Claims

[1] Mechanical seal device (1) with a mechanical seal (10), wherein the latter has a dry-running protection device (20), wherein the dry-running protection device (20) has at least one microsystem (21) which outputs a digital measured value (W), wherein the microsystem (21) is arranged adjacent to the mechanical seal (10) and / or on and / or in the mechanical seal (10), wherein the microsystem (21) has a power generator, wherein the power generator is an induction-based electrical generator. [2] Mechanical seal device (1) according to claim 1, characterized by that the microsystem (21) has a MEMS chip (26). [3] Mechanical seal device (1) according to one of claims 1 or 2, characterized by that the microsystem (21) has a temperature sensor (22) and the digital measured value (W) is a temperature value. [4] Mechanical seal device (1) according to claim 3, characterized bythat a measuring point (23) of the temperature sensor (22) is an area of ​​the mechanical seal (10). [5] Mechanical seal device (1) according to one of the preceding claims, characterized by that the microsystem (21) has a pressure sensor (24) and the digital measured value (W) is a pressure value acting on the mechanical seal (10). [6] Mechanical seal device (1) according to one of the preceding claims, characterized by that the microsystem (21) has a wired and / or wireless data interface (25) for outputting the digital measured value (W). [7] Mechanical seal device (1) according to one of the preceding claims, characterized by that the microsystem (21) is encapsulated in the mechanical seal (10). [8] Mechanical seal device (1) according to one of the preceding claims, characterized by that the microsystem (21) is operated autonomously by means of the power generator. [9] Mechanical seal device (1) according to one of the preceding claims, characterized by that the induction of the induction-based electrical generator is caused by relative rotation between a) a mechanical seal ring and a counter ring of the mechanical seal, or b) between a rotating shaft and a stationary counter ring. [10] Mechanical seal device (1) according to one of the preceding claims, characterized by that the microsystem (21) has an energy storage device. [11] Mechanical seal device (1) according to one of the preceding claims, characterized by that the microsystem (21) has a wired power connection. [12] Pump device (100) with - a pump housing (101) in which a shaft passage (102) is formed, - with a pump shaft (103) which projects rotatably into the shaft passage (102), and - with a mechanical seal device (1) according to one of the preceding claims, wherein the mechanical seal (10) is arranged in the shaft passage (102) and sits on the pump shaft (103). [13] Pump device (100) according to claim 12, characterized by that the microsystem (21) is connected to a frequency converter of a drive motor (105) of the pump shaft (103). [14] Pump device (100) according to claim 13, characterized by that the speed of the drive motor (105) of the pump shaft (103) correlates with the digital measured value (W) of the microsystem (21). [15] Method for operating a pump device (100) according to one of claims 12 to 14, wherein the rotational speed of a drive motor (105) of the pump shaft (103) is adjusted based on the digital measured value (W) of the microsystem (21). [16] Method according to claim 15, wherein the digital measured value (W) is a temperature value and the speed of the drive motor (105) is regulated down when a limit temperature is exceeded.

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