Seal device and seal assembly with sensor system for condition monitoring

Abstract

The invention relates to a sealing device (18) having a sensor system (54) for condition monitoring. The sealing device comprises: a sealing ring (26) having a dynamic sealing section (34) for dynamically sealingly abutting against a sealing surface (40) of a machine part (12, 14); and a preload ring (28) for preloading the sealing section against the sealing surface (40), the preload ring having a first section (42) and a second section (44), wherein the second section (44) can be elastically deflected from a first position relative to the first section in an axial or radial direction relative to a central axis (38) of the sealing device (18). The sensor system (54) comprises at least one measuring element (56) arranged in an intermediate space (48) on the preload ring (28), the measuring element responding directly or indirectly to the deflection movement of the first section (44) of the preload ring (28). The invention also relates to a sealing assembly having the sealing device.

Description

Background Art

[0001] Dynamic seals have the task of preventing or reducing to a permissible extent the exchange of substances from one space to another between two components that move relative to one another. The dynamic seals are important safety- and function-relevant components in many systems. If the dynamic seals fail, this leads to functional limitations or even to functional failures of the entire system or to the release of hazardous substances. In order to avoid this, regular maintenance or replacement is clearly necessary before the expected time of a seal failure, especially in system-critical applications.

[0002] In order to be able to flexibly design maintenance intervals and thereby reduce system downtimes to a minimum, on-site condition monitoring of the seal is desirable. For this purpose, sensors are increasingly being integrated into the seal in the immediate vicinity of the dynamic sealing section of the seal in order to be able to infer the function of the seal and the wear and tear caused by the service life.

[0003] For example, sealing devices with such sensor systems for condition monitoring of dynamic sealing devices are known from US Pat. No. 10,458,551 B2 and US Pat. No. 10,371,179 B2. The integration of the sensor system into the sealing device carries the risk of negatively affecting the actual function and service life of the sealing device. In addition, the known sealing devices are complex to manufacture and can only be realized under certain conditions, especially in small structural dimensions. Summary of the invention

[0004] The object of the present invention is therefore to specify a seal and a seal assembly having a sensor system for condition monitoring of the seal, wherein negative influences on the sealing function and the service life of the seal are avoided and the seal can be produced easily and cost-effectively.

[0005] The object relating to the sealing device is achieved by a sealing device having the features specified in claim 1. The sealing assembly according to the invention has the features specified in claim 15. Preferred further developments of the invention are the subject matter of the dependent claims and the description. Further advantages of the invention are apparent from the description and the drawings.

[0006] The sealing device with a sensor system for condition monitoring according to the present invention comprises a sealing ring having a sealing section for sealingly abutting against a sealing surface of a machine part. The dynamic sealing section is preferably implemented as a dynamic sealing section for dynamically sealingly abutting against the sealing surface. The preload ring is used to preload the sealing section onto the sealing surface and has a first section and a second section, which jointly define the boundary of the intermediate space. One of the two sections can be elastically offset from a first position relative to the corresponding other section of the two sections in a radial or axial direction relative to the central axis of the sealing device. In the case of a radial sealing ring, in the radial direction, and in the case of an axial sealing ring, in the axial direction. The sensor system comprises at least one measuring element, which is arranged in the intermediate space of the preload ring, and the measuring element directly or indirectly responds to the offset movement of the section of the preload ring.

[0007] In the sealing device according to the invention, the transverse force or lateral force acting on the sealing ring or the resulting movement of the sealing ring or preload ring can be determined during operation by means of the sensor system. Based on the information, information about the relative movement of two machine parts sealed from each other by the sealing device, in particular the acceleration, stroke, movement mode, etc. of the relative movement can be determined during operation of the sealing device. Based on the aforementioned information, the size and time curve of the pressure difference applied by the sealing element during operation can be inferred and the functional state of the sealing ring and also the remaining service life of the sealing ring can be inferred. By arranging the measuring element of the sensor system in the intermediate space of the preload ring, it is possible to avoid negatively affecting the function and service life of the sealing ring. In addition, the sealing device is easily and cost-effectively realized.

[0008] According to the invention, the sensor system preferably has a plurality of, in particular exactly three or exactly four, measuring elements, which are preferably arranged regularly spaced apart from one another in the circumferential direction of the preload ring. It is understood that the sensor system can also have more than four measuring elements, in particular in the case of larger diameters of the preload ring. This allows the measurement data to be determined spatially resolved on the circumference of the preload ring. This allows more accurate, more reliable and more convincing inferences about the function and the remaining service life of the sealing ring.

[0009] According to a preferred further development of the invention, the two sections of the preloading ring each comprise a permanent magnet, or the two sections of the preloading ring together form a permanent magnet in such a way that a magnetic field is formed between the two sections of the preloading ring. The measuring element in this configuration is preferably implemented in the form of a Hall sensor, by which changes in the magnetic field can be detected. The preloading ring can be made of a material with permanent magnetic properties in a cost-effective and simple manner. In this case, the number of required parts can be kept small. As a result, the fixing of a separately constructed permanent magnet on the preloading ring can be completely eliminated.

[0010] According to a further embodiment of the invention, the measuring element can be arranged in the intermediate space in such a way that the measuring element is deformed at least in sections by the displacement of the first section relative to the second section in the radial direction. The measuring element here preferably at least in sections performs an axial movement or a relative movement directed in the circumferential direction of the preload ring relative to the preload ring, which can be detected by a (separate) sensor. In this case, the measuring element is thus designed as a mechanical actuator, which interacts with the sensor.

[0011] According to a preferred further embodiment of the present invention, the measuring element can preferably include a constant-volume, compressible elastomeric material, which extends from the first section of the preload ring to the second section. According to the present invention, the measuring element can be equipped with a sensor that works contactlessly. According to one embodiment, the sensor can be a distance sensor, by which the distance between the sensor and the measuring element can be determined optically or by means of ultrasound. The measuring element can have a measurement mark for the sensor at a predetermined position, which measurement mark is composed of a material different from the rest of the measuring element. This can improve the measurement accuracy of the distance measurement and resist erroneous measurements when necessary.

[0012] According to an alternative further embodiment of the invention, the measuring element is constructed in the form of a spring element, which extends from the first section to the second section and contacts one end of the distance sensor. According to the invention, the measuring element can be arranged to be clamped on one of the two sections with a press fit or to be fixed on one of the two sections in another way, in particular to be bonded to the section or fixedly welded to the section.

[0013] According to the invention, the distance sensor can be a continuous or discrete distance sensor. The distance sensor can in particular comprise a resistive film or a capacitive film or consist of said resistive film or capacitive film. The distance sensor or the film is preferably fixed, in particular glued or welded, to the inner wall of one of the two segments, which inner wall faces the respective other segment.

[0014] In terms of structure and manufacturing technology, the preload ring is preferably implemented in one piece. In this configuration, the two sections of the preload ring can extend away from the back section or flank section of the preload ring, especially in the axial direction. Most preferably, the preload ring has a V-shaped or U-shaped cross-sectional shape. As a result, the preload ring can be produced in a simple manner with the help of traditional manufacturing methods. In addition, the preload ring can provide its two sections or sides with a certain spring elasticity. As a result, the response characteristics of the preload ring to the force acting on the preload ring can be reliably adjusted to a predetermined value. Overall, a large range of use of the sealing device can be ensured.

[0015] According to the invention, the preload ring can consist of plastic, in particular permanently magnetic plastic, of metal, in particular steel, or of a composite material.

[0016] The aforementioned measuring element can be arranged on a supporting element (independent of the implementation of the preload ring) together with the respectively configured sensors according to the present invention. The supporting element, the measuring element and the sensor thus constitute an assembly unit that can be easily manipulated by hand. The supporting element can be implemented, for example, in the form of a particularly open hose. The hose can be extruded. The measuring element / sensor is placed in the hose in this configuration. Alternatively, the supporting element can also be produced together with the measuring element by a 3D printing method. The sensor is placed in the supporting element or fixed on the supporting element in this configuration. It can be achieved that the measuring element / sensor is particularly easily assembled on the sealing device. In addition, the assembly unit can be segmented in a simple manner in the area of ​​the predetermined separation area with the size required for the corresponding preload ring. This is advantageous for the manufacturing cost of the sealing device and the sealing assembly.

[0017] The sealing assembly according to the invention comprises a first machine part and a second machine part, which are arranged at a distance from each other while forming a sealing gap. The two machine parts can move relative to each other along an axis of movement and / or around an axis of movement. The aforementioned sealing device is used to seal the sealing gap, and the sealing ring of the sealing device rests sealingly with its sealing section on one of the two machine parts. In the sealing assembly according to the invention, the maintenance interval of the sealing device or the sealing ring can be determined in accordance with the requirements based on the data that can be determined with the aid of the sensor system, which is beneficial on the one hand to operational safety and on the other hand to the costs associated with maintenance. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The invention is explained below with the aid of the exemplary embodiments described in the drawings. The embodiments shown and described are not to be understood as a definitive enumeration, but rather have exemplary characteristics for describing the invention. In the drawings:

[0019] Figure 1 A sealing assembly with two machine parts is shown, which are sealed from one another by a sealing arrangement with a preload ring and a dynamic sealing ring, wherein the preload ring is provided with a sensor system for condition monitoring of the sealing ring;

[0020] Figure 2 Shown in exposed side view according to Figure 1 Sealing device;

[0021] Figure 3 Show according to Figure 1 a first embodiment of a sealing device with a measuring element arranged between two segments of a preload ring, which measuring element responds to a deformation of the preload ring caused by radial forces and which interacts with a distance sensor;

[0022] Figure 4 Show according to Figure 3 Schematic functional diagram of the measuring element;

[0023] Figure 5 Show according to Figure 1 a further embodiment of the sealing device with a measuring element arranged between two sections of the preload ring, which measuring element responds to the deformation of the preload ring and converts the deformation into an axial movement that can be detected by a sensor;

[0024] Figure 6 Show according to Figure 1 A further embodiment of the sealing device of , wherein the preload ring comprises a permanent magnet, a field change of which can be detected by a measuring element in the form of a Hall sensor arranged between two sections of the preload ring;

[0025] Figure 7 Show according to Figure 1 A further embodiment of the sealing device, in which an elastomeric measuring element is arranged between two sections of the preload ring, which elastomeric measuring element interacts with a pressure-sensitive sensor; and

[0026] Figure 8 A sealing device is shown, in which the measuring element arranged in the intermediate space of the preload ring is embodied in the form of a piezoelectric element;

[0027] Fig. 9 The support element is shown in a side view, with a support element fastened thereto for Figure 1-3 The sensor system of the sealing device. DETAILED DESCRIPTION

[0028] Figure 1A sealing arrangement 10 is shown which has a first and a second machine part 12, 14 which are arranged at a distance from one another, forming a sealing gap 16. The two machine parts 12, 14 are movable relative to one another along a movement axis designated by A. The sealing arrangement 10 can be designed, for example, as a hydraulic cylinder, so that the first machine part 12 in this case is a cylinder liner and the second machine part 14 is a piston rod.

[0029] The seal 18 serves to seal the high-pressure side H of the sealing gap 16 relative to the outside or low-pressure side N. The seal 18 is arranged to be held in a retaining groove 20 of one of the two machine parts 12, 14. The retaining groove 20 has two groove sides 22 facing each other and a groove bottom 24.

[0030] The sealing device 18 comprises a sealing ring 26 and a preload ring 28. The sealing ring 26 has a foot section or retaining section 30 and a sealing lip 32, which has a dynamic sealing section 34. The retaining section 30 and the sealing lip 32 are connected to one another via a connecting section 36. Overall, the sealing ring 26 has a V-shaped cross-sectional shape.

[0031] The preload ring 28 is used to preload the sealing section 36 of the sealing ring 26 onto the sealing surface 40 of the second machine part 14 in a dynamic sealing manner in a radial direction relative to the central axis 38 of the sealing device 18. The central axis 38 of the sealing device coincides with the movement axis A of the two machine parts 12, 14 in its assembled state. The preload ring 28 has a substantially V-shaped cross-sectional shape with a first section 42 and a second section 44, which are connected to each other by a back section 46. The two sections 42, 44 can be elastically moved relative to each other in the radial direction from their shown starting position. An intermediate space 48 is formed between the two sections 42, 44. The sealing ring 26 has a static sealing section 50. The static sealing section 50 here rests against the groove bottom 24 of the retaining groove 20 in a static sealing manner in the radial direction.

[0032] The sealing ring 26 can be made of a material that can be deformed rubber-elastically or duroelastically. The sealing ring 26 has a smaller module than the preload ring 28. The material of the sealing ring 26 can be injection-molded onto the preload ring 28. The sealing device 18 is implemented as a prefabricated structural unit. The evaluation unit is marked with 52, the function of which is explained in more detail below. The evaluation unit 52 can be arranged on one of the two machine parts 12, 14 or at a distance from the machine part. It is understandable that the two machine parts 12, 14 of the sealing assembly can be adjusted to rotate relative to each other around the movement axis A alternatively or additionally. In addition, the two machine parts 12, 14 can also be arranged fixedly relative to each other. In this case, the sealing section of the sealing ring 26 is implemented as a static seal. The sealing ring 26 can also be implemented as a scraper sealing ring. In this case, according to Figure 1 The high-pressure side H and the low-pressure side N of the sealing gap 16 are arranged interchangeably.

[0033] Figure 2 The sealing device 18 is shown in an exposed side view. The sealing device 18 comprises a sensor system, generally designated by 54, which is used for monitoring the condition of the sealing ring 26. The sensor system 54 comprises a plurality of, preferably three or four, measuring elements 56, which are each arranged in the intermediate space 48 of the preload ring 28 and are preferably arranged regularly spaced apart from one another in the circumferential direction of the sealing device 18. The sensor system 54 is connected to an evaluation unit 52 ( Figure 1 )coupling.

[0034] The sensor system 54 of the sealing device 18 can be designed in different ways. Figure 3 In the embodiment shown in the figure, the measuring element 56 is arranged in the intermediate space 48 of the preload ring 28 in such a way that the measuring element 56 at least partially performs a relative movement directed in the circumferential direction of the preload ring 28 due to the relative movement of the two machine parts 12, 14 or the displacement of the second section 44 in the radial direction relative to the first section 42, which relative movement can be detected by the sensor 58.

[0035] The measuring element 56 is designed here in the form of an angled leaf spring having a first side and a second side 60, 62. The two sides 60, 62 are connected to one another in a corner region 64 of the measuring element 56 and are preferably designed with the same length. In the initial state of the sealing assembly 10 ( Figure 1 ) together enclose an angle α between 50° and 150°, preferably between 70° and 140°.

[0036] The two free ends 66 of the measuring element 56 are assigned to or allocated to one of the two sections 42, 44 of the preload ring 28, while the corner region 64 is assigned to or allocated to the respective other section 42, 44. One of the sides 60, 62 can be fixed immovably at one end of one of the two sections 42, 44 of the preload ring 28, here exemplarily at the first section. The measuring element 56 is preferably made of metal as a whole. A sensor 58 is assigned to the measuring element 56, which is constructed independently of the measuring element 56. The sensor 58 is here a distance sensor 58, by which the movement of the free end of the second side 62 of the measuring element 56 relative to the sensor 58 can be detected in a position-resolved manner (discretely or continuously). The sensor 58 can, for example, include a pressure-sensitive film or be formed by a pressure-sensitive film.

[0037] The sensor 58 can be fastened in particular to the inner side 68 of the first section 42, which faces the second section 44. Thus, the sensor 58 can be adhesively bonded to the inner side 68 or welded to the first section, for example. Other fastening methods can be provided without problems. The protected arrangement of the sensor 58 protects the sensor well from mechanical damage, which can occur, for example, when the seal 18 is installed.

[0038] If a radial force F acts on the second section 28 of the preload ring, by which the second section is elastically deflected in the radial direction from its original position, this Figure 3 In the embodiment shown in FIG. 5 , a compression of the measuring element 56 associated with this deflection is caused. As a result, the free end 66 of the second side 62 of the measuring element 56 moves in the activation direction while being supported on the sensor 58, for example, in Figure 3 The measuring element 56 is shown in a dashed view.

[0039] According to Figure 4 , as a basic length C covered by the measuring element 56 when the measuring element 56 is compressed. 1 The basic length C in the original state 0 The difference Δx travelled by the free end of the measuring element 56 is related to the deflection of the second section 44 of the preload ring 28, i.e. to the height h of the measuring element in the initial state due to the compression of the measuring element 56. 0 is related to the reduction of .

[0040] The following apply here:

[0041]

[0042]

[0043] Here, a is the respective length of the two sides 60 , 62 of the measuring element 56 , and h 0 is the height of the measuring element 56 in the original state, and h 1 is the height of the measuring element in the activated state.

[0044] The corresponding output signal of the sensor 58 assigned to the measuring element can thus be clearly assigned to a certain deflection of the second section 44 of the preload ring. Based on the measurement signal of the sensor 58, the state monitoring of the sealing device 18, in particular the sealing ring 26, and also the state monitoring of the operating state of the sealing assembly 10 can be carried out. This is preferably done by means of the evaluation unit 52 ( Figure 1 )conduct.

[0045] According to a further embodiment, the measuring element 56 designed as an angled leaf spring element can be arranged between the two sections 42, 44 of the preload ring 28 in such a way that the compression of the measuring element 56 caused by the radial force F leads to a force or a movement of the free end 66 of the measuring element 56 directed in the axial direction, which can be detected and quantified by the sensor 58. In this case, the two free ends of the measuring element 56 can be arranged to be clamped separately between the two sections of the preload ring 28, or at least one edge 60, 62 of the measuring element 56 can be fixed to the two sections of the preload ring 28. According to Figure 5 Alternatively to the embodiment shown in FIG. 5 , the corner region 64 of the mechanically deformable measuring element 56 can also be assigned to the sensor 58. The sensor 58 can in this case be a distance sensor that works without contact, for example an ultrasonic sensor or an optical sensor 58, but can also be configured according to Figure 5 is a pressure-sensitive sensor which is in permanent contact with the measuring element 56. Each of the sensors 58 shown in the figures can have a device for wirelessly transmitting the measuring signal to an evaluation unit ( Figure 1 )'s transmitter 58a.

[0046] according to Figure 6 , the state monitoring of the sealing ring 26 can also be carried out by means of a measuring element 56 in the form of a Hall sensor 58. The two sections 42, 44 of the preload ring 28 can here jointly form a permanent magnet 70. One of the two sections 42, 44 of the preload ring 28 forms the north pole N, and the other section 42, 44 forms the corresponding south pole S of the permanent magnet 70, so that a magnetic field B is formed between the two sections 40, 42. The measuring element 56 is designed as a Hall sensor in this case, by which changes in the magnetic field can be detected. The measuring element 56 is arranged in the intermediate space 48 and can be fixed, for example, on the first section 42 of the preload ring 28.

[0047] According to an embodiment not specifically shown in the figures, the two segments 42, 44 of the preload ring 28 can also each have a permanent magnet 70 arranged complementary to one another, by which a magnetic field is generated in the intermediate space 48 of the two segments of the preload ring 28. The permanent magnet 70 can be glued, welded or fixed to the segments 42, 44 in another suitable manner, for example.

[0048] The measuring element 56 can be based on Figure 7 The embodiment shown in FIG. 1 comprises a preferably volume-constant, compressible elastomeric material which extends from a first section of the preload ring 28 to the second sections 42, 44. The measuring element 56 can be fastened, in particular adhesively bonded, to one or both sections of the preload ring 28. The measuring element 56 is also assigned a sensor 58 which preferably operates without contact. The sensor can be similar to Figure 5 The exemplary embodiment shown in the figure is a distance sensor or also a pressure-sensitive sensor. The measuring element 56 can have a measuring mark 72 for the sensor 59, which is formed by a different material from the rest of the measuring element 56. This can simplify the calibration of the relevant sensor 58 if necessary and prevent incorrect measurements during operation. This applies in particular to sensors 58 that work without contact.

[0049] according to Figure 8 In the embodiment described in , the measuring element 56 in the intermediate space 48 of the two sections of the preload ring 28 can also be formed by a piezoelectric element. The piezoelectric element is pressure-sensitive and generates a measuring signal as a function of the force component acting on the piezoelectric element by the radial force-dependent deflection of the second section 44 of the preload ring.

[0050] according to Fig. 9 , the aforementioned measuring element 56 and the sensor 58 interacting with the measuring element 56 can be arranged together on the supporting element 74 (implemented independently of the preload ring 28). The supporting element 74, the measuring element 56 and the sensor 58 thus constitute an assembly unit 76 that is easily manipulated by hand. The supporting element 74 can be implemented, for example, in the form of a particularly open hose. The hose can be extruded. The measuring element 56 is placed in the hose in this configuration. Alternatively, the supporting element 74 can also be produced together with the measuring element 56 by a 3D printing method. The sensor 58 is placed in the supporting element 74 or fixed on the supporting element 74 in both cases. It is thus possible to achieve a particularly easy assembly of the sealing device. In addition, the assembly unit 76 can be segmented in a simple manner in the area of ​​a predetermined separation area with the size required for the corresponding preload ring.

[0051] The measurement signals of the aforementioned measuring elements 56 or sensors 58 can be transmitted wired or wirelessly to the evaluation unit 52. Information about the functional state of the sealing ring 26, the sealing device 18 or the entire sealing assembly 10 can be derived from the measurement signals. The sensor system 54 can also be provided with an independent energy supply device or energy collection unit, which is not specifically shown in the drawings.

Claims

1. A sealing device (18) having a sensor system (54) for condition monitoring, comprising: a sealing ring (26) having a first sealing section (34) for sealingly abutting against a sealing surface (40) of a machine part (12, 14); a preloading ring (28) for preloading the sealing segment onto the sealing surface (40), the preloading ring having a first segment (42) and a second segment (44), the first segment and the second segment jointly delimiting an intermediate space (48), wherein: One of the two sections (42, 44) is elastically displaceable from a first position relative to the corresponding other section of the two sections (42, 44) in a radial or axial direction relative to a central axis (38) of the sealing device (18); wherein the sensor system (54) comprises at least one measuring element (56) which is arranged in the intermediate space (48) of the preload ring (28) and which responds directly or indirectly to the deflection movement of the segment (44) of the preload ring (28), wherein the measuring element (56) is arranged in the intermediate space (48) in such a way that an axial movement of the measuring element (56) or a deformation directed in the circumferential direction of the preload ring (28) is at least partially caused by a displacement of one of the two segments (42, 44) in the radial or axial direction relative to the respective other segment of the two segments (42, 44), the axial movement or deformation being detectable by a sensor (58), It is characterized in that The measuring element (56) is a spring element which extends from the first section (42) to the second section (44) and which interacts with the sensor (58).

2. The sealing device (18) according to claim 1, characterized in that The sensor (58) is a continuous or discrete distance sensor.

3. The sealing device (18) according to claim 2, characterized in that The sensor (58) is a resistive sensor or a capacitive sensor.

4. The sealing device (18) according to claim 2 or 3, characterized in that: The sensor (58) is fastened to an inner side (68) of one of the two sections (42, 44).

5. The sealing device (18) according to claim 1 or 2, characterized in that: The sensor system (54) includes a plurality of measuring elements (56) and / or sensors (58) which are arranged at intervals from one another in a circumferential direction of the preload ring (28).

6. The sealing device (18) according to claim 5, characterized in that The measuring element (56) and the sensor (58) are arranged together on a carrier element (74) which is arranged to be held between the two sections (40, 42) of the preload ring.

7. The sealing device (18) according to claim 6, characterized in that The support element (74) is implemented in the form of a hose, or the support element (74) and the measuring element (56) are implemented together as a 3D-printed part.

8. The sealing device (18) according to claim 1 or 2, characterized in that: The preload ring (28) is embodied in one piece.

9. The sealing device (18) according to claim 1 or 2, characterized in that: Two sections (42, 44) of the preload ring (28) extend away from a back section (46) of the preload ring (28).

10. The sealing device (18) according to claim 1 or 2, characterized in that The preload ring (28) has a V-shaped or U-shaped cross section.

11. The sealing device (18) according to claim 1 or 2, characterized in that The preload ring (28) is made of plastic, metal, or a composite material.

12. A sealing assembly (10), comprising: a first machine part (12) and a second machine part (14), which are arranged at a distance from one another, forming a sealing gap (16), and are movable relative to one another along or about an axis of movement; and The sealing device (18) according to claim 1 or 2, wherein the sealing ring (26) of the sealing device bears with its sealing section (34) in a sealing manner against one of the first machine part (12) and the second machine part (14).

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