SEALING STRIP AND SEALING DEVICE

Abstract

A sealing strip and a sealing device for sealing a negative-pressure zone of a suction roller for a machine for producing or processing a fibrous web, such as a paper, board or tissue machine. The stealing strip has an upper face, which forms a sealing surface of the sealing strip, and the sealing strip includes a sensor unit, which has a first temperature sensor at a first distance from the sealing surface and a second temperature sensor at a second distance from the sealing surface. The first distance is smaller than the second distance. The sealing strip is formed of a base material and a protective material which is different from the base material, and the sensor unit is embedded, in particular cast, into the protective material.

Claims

1-14. (canceled)

15. A sealing strip for a sealing device for sealing off a negative pressure zone of a suction roll in a machine for producing or processing a fibrous web, the sealing strip comprising: a sealing strip body formed of a base material and a protective material, said protective material being different from said base material; said sealing strip body having a top forming a sealing surface of the sealing strip; a sensor unit having a first sensor disposed at a first distance from said sealing surface and a second sensor disposed at a second distance from said sealing surface, said first distance being smaller than said second distance; and said sensor unit being at least partly embedded in said protective material and at least one of said first or second sensors is a temperature sensor.

16. The sealing strip according to claim 15, wherein said sensor unit is completely embedded in said protective material, said protective material is a potting material, and both of said first and second sensors are temperature sensors.

17. The sealing strip according to claim 15, wherein said first sensor and said second sensor, viewed in a width direction of the sealing strip, are separated from one another by said protective material.

18. The sealing strip according to claim 15, wherein said base material contains or consists of graphite.

19. The sealing strip according to claim 15, wherein said protective material contains or consists of a polymer material.

20. The sealing strip according to claim 15, wherein said sensor unit includes a control unit that is connected or connectible to at least one of said first sensor or said second sensor.

21. The sealing strip according to claim 20, wherein said sensor unit further comprises a third sensor and a fourth sensor that are connectible to said control unit.

22. The sealing strip according to claim 20, wherein said sensor unit comprises a power supply for supplying at least one of said sensors or said control unit.

23. The sealing strip according to claim 15, wherein said sensor unit comprises a transmission device configured to make a data connection to an evaluation unit outside the sealing strip.

24. The sealing strip according to claim 23, wherein said transmission device is configured to establish a wire-free data connection to the evaluation unit.

25. The sealing strip according to claim 15, wherein said first sensor is attached to a first circuit board and said second sensor is attached to a second circuit board, and wherein both said first circuit board and said second circuit board are embedded in said protective material.

26. The sealing strip according to claim 25, wherein said first and second circuit boards are potted in said protective material.

27. The sealing strip according to claim 15, wherein said sensor unit is one of two or more sensor units.

28. The sealing strip according to claim 15, configured for a paper machine for producing or processing a paper, board or tissue web.

29. A sealing device for sealing off a negative pressure zone of a suction roll for a machine for producing or processing a fibrous web, the sealing device comprising at least one sealing strip according to claim 15.

30. The sealing device according to claim 29, configured for a paper machine for producing or processing a paper, board or tissue web.

31. The sealing device according to claim 29, further comprising an evaluation unit that is coupled or couplable to a control unit of said sealing strip via a data connection.

32. The sealing device according to claim 31, wherein the data connection is a wire-free data connection.

33. The sealing device according to claim 31, wherein said evaluation unit is configured to visualize a temperature and wear data of said sealing strip.

Description

[0064] Further advantageous expressions of the invention will be explained by using exemplary embodiments and with reference to the drawings. The features mentioned can be implemented advantageously not only in the illustrated combination but also combined individually with one another. In detail in the figures:

[0065] FIG. 1 shows a sealing strip as is known from the prior art.

[0066] FIG. 2 shows a sealing strip which is designed according to one aspect of the invention.

[0067] FIG. 2b shows a sealing strip according to a further aspect of the invention.

[0068] FIG. 3 shows a sealing strip according to a further aspect of the invention.

[0069] FIG. 4 shows a sealing strip according to a further aspect of the invention.

[0070] FIG. 5 and FIG. 5a show a detail from a sensor unit, as can be used for a sealing strip according to aspects of the invention.

[0071] FIG. 6 shows a detail of a suction roll which is equipped with a sealing device according to one aspect of the invention.

[0072] The figures are described in more detail below.

[0073] FIG. 1 shows a detail from a sealing strip as is known from the prior art. A plurality of sensor units 2 are provided in the sealing strip 1. Each of the sensor units has four temperature sensors 2.1, 2.2, 2.3, 2.4, which are arranged at a different distance from the top 10 of the sealing strip 1. The temperature sensors 2.1, 2.2, 2.3, 2.4 are mounted on a common circuit board 5, together with a control unit 3 and a battery 4 for the power supply. The sensors 2.1, 2.2, 2.3, 2.4 are seated directly in the base material 20 of the sealing strip 1. For the lower part of the circuit board 5, a cavity is provided in the strip 1. If, in this embodiment of a strip, the first temperature sensor 2.1 is destroyed by wear, moisture can penetrate at this point, which propagates along the circuit board 5, largely unimpeded, in the direction of the other sensors 2.2, 2.3, 2.4 and the electrical and electronic components, and can destroy these components.

[0074] By contrast, FIG. 2 shows a sealing strip 1 having a sensor unit 2 which is designed according to one aspect of the invention. Here, too, for example four temperature sensors 2.1, 2.2, 2.3, 2.4 are arranged on a common circuit board 5 with a control unit 3 and a suitable power supply 4. The temperature sensors 2.1, 2.2, 2.3, 2.4 are connected to the control unit 3 via suitable lines 7.

[0075] As distinct from FIG. 1, the sensor unit 2 from FIG. 2 is, however, embedded in a protective material 30, specifically potted. The protective material 30 can be, for example, a polymer material 30. The protective material 30 differs from the base material 20 of the sealing strip 1, which usually consists of a graphite or comprises the latter. The protective material 30 encloses the sensor unit 2 either—as shown in FIG. 2—completely or in parts. In particular, the temperature sensors 2.1, 2.2, 2.3, 2.4 can preferably be enclosed by the protective material 30 wholly or in large parts.

[0076] This protective material 30 advantageously adheres to the temperature sensors 2.1, 2.2, 2.3, 2.4 and/or the circuit board 5.

[0077] Even if not explicitly mentioned, in all examples the control unit 3 can comprise a transmission device or be connected thereto, in order to build up a data connection, in particular a wire-free data connection, to an evaluation unit outside the sealing strip. Such a wire-free data transmission can be carried out, for example, via Bluetooth, WLAN or the like.

[0078] In the embodiment in FIG. 2 the circuit board 5 is additionally further provided with incisions 6. Thus, a distance in the CD direction between adjacent temperature sensors 2.1, 2.2, 2.3, 2.4 is produced, which is filled with protective material 30. Thus, in addition the penetration of moisture from a worn sensor to its still intact neighboring sensor is hampered. The width of the incisions 6 should preferably be at least 1 mm, particularly preferably at least 5 mm or 10 mm. Technologically, even considerably greater distances of 200 mm, 500 mm or more are desirable. Since such circuit boards 5 become cumbersome, however, alternative designs for this purpose will also be described in further figures.

[0079] With regard to the depth of an incision, it is advantageous if this reaches at least 2 mm, preferably 5 mm, particularly preferably 10 mm or more below the position of the deeper of the two sensors.

[0080] FIG. 2b shows a variant of the strip 1 from FIG. 2. The two strips 1 differ only in the fact that in FIG. 2 the entire sensor unit 2 together with the protective material 30 is located in the interior of the strip 1 and is completely surrounded by base material 20. In FIG. 2b, on the other hand, part of the underside 11 of the strip 1 is formed by protective material 30. This may be advantageous in terms of fabrication. The sensor unit 2 can be inserted from below into a suitable recess in the base material 20 of the strip 1 and potted with the protective material 30. Alternatively, a sensor device 2 already embedded in protective material 30 can also be inserted simply into the strip via the underside.

[0081] The embodiment in FIG. 3 shows a strip 1 according to a further aspect of the invention. The sensor unit 2 is now no longer arranged on a single circuit board 5. Instead, each temperature sensor 2.1, 2.2, 2.3, 2.4 is attached to a separate circuit board 5.1. Still further elements can be attached to each of these circuit boards 5.1. In particular, the control unit 3 and/or the power supply 4 which, in FIG. 3, are provided on an individual, separate circuit board 5 together with one of the temperature sensors can be provided on a common circuit board. Here, it is recommended for the control unit together with that temperature sensor 2.4 which is furthest removed from the top 10 to be attached to a circuit board.

[0082] The lines 7 for connecting the sensors 2.1, 2.2, 2.3, 2.4 to the control unit can be formed wholly or partly as a cable connection.

[0083] The incisions 6 of the sensor unit 2 shown in FIGS. 2/2b are replaced in FIG. 3 by the distances of the sensors from one another. These distances can be dimensioned analogously to the incisions.

[0084] While, in the sensor unit 2 in FIG. 3, a common circuit board 5 has already been dispensed with, in this embodiment the individual components are still embedded in the protective material 30 and joined together such that the entire sensor unit 2 is present as an individual element.

[0085] The embodiment in FIG. 4 shows, by way of example, that it is also possible to design sealing strips 1 according to one aspect of the invention in which the sensor unit 2 comprises a plurality of separate parts. The sensor unit 2 is substantially constructed in the same way as the unit in FIG. 3, but only the temperature sensors with their circuit boards are now embedded individually in protective material 30. The sensor packages comprising the temperature sensor 2.1, associated circuit board 5.1 and the embedding protective material 30 are in principle freely movable and only connected to the control unit 3 via lines 7. In this way, the temperature sensors 2.1, 2.2, 2.3, 2.4 can be positioned comparatively simply even with large distances of 200 mm, 500 mm or more from one another and from the control unit 3. This not only increases the reliability in the event of the penetration of moisture; it also permits simple monitoring of the strip 1 over its entire width.

[0086] If the third temperature sensor 2.3 and the fourth temperature sensor 2.4, for example, again have the first distance from the surface 10, the uniformity of the strip wear can thus be checked.

[0087] Furthermore, the sensor unit 3 in FIG. 4 shows that it is not necessary for the entire sensor unit 2 to be enclosed by protective material 30. By way of example here, the circuit board 5 of the control unit 3 is only partly enclosed by protective material 30. Within the context of the invention, a design is also conceivable in which the circuit board, together with the control unit 3, is not enclosed by protective material 30 at all. In these two ways, for example, it is possible to prevent sensitive electronics from being damaged by the embedding in protective material 30—for example by the temperature of the molten protective material 30 during the potting.

[0088] FIGS. 5a and 5b each show a lateral section of a temperature sensor 2.1 on a circuit board 5.1, which can each be used as a temperature sensor 2.1 for a sensor unit 2 in a strip 1 according to various aspects of the invention. While protective material 30 at the side, on the front, at the rear and underneath the temperature sensor 2.1 can prevent further penetration of moisture following the wear of the sensor 2.1, protective material 30 above the temperature sensor 2.1, i.e. in the direction of the top 10 of the strip, is not able to make any contribution thereto. This is because protective material 10 provided there will already be removed by the moving roll cover before the actual sensor is destroyed. To this extent, it may be very advantageous if no protective material 30 is provided above the actual temperature sensor 2.1, 2.2, 2.3, 2.4, as shown in FIG. 5b, or if this protective material 30 is removed before the installation of the sensor device 2 in the body of the strip.

[0089] This is also advantageous, amongst other things, since the sensor position in the thickness direction, that is to say the distance of the temperature sensor 2.1, 2.2, 2.3, 2.4 from the top 10, can be determined very simply and accurately which, in the event of being covered with protective material 30, is possible only with a great deal of effort since, for this purpose, the exact thickness of the covering with protective material 30 must be known. If it is considered that the wear of a sealing strip 1 takes place comparatively slowly and even inaccuracies of tenths of millimeters in the determination of the first distance or of the second distance can lead to significant errors in the determination of the remaining service life of the sealing strip 1, the simple possibility of the accurate positioning of the sensors is a quite significant advantage.

[0090] FIG. 6 shows, by way of example, the installation situation of a sealing device according to one aspect of the invention in a suction roll.

[0091] Here, the sealing device comprises two sealing strips 1, which are each mounted in a strip holder 300. By means of a pressure hose 350, the strips 1 are pressed against the cover 100 of the suction roll. The sealing strips 1 seal off a negative pressure zone 200. As a result of pressing the sealing strips 1 against the rotating roll cover 100, the material wears, in particular the base material 20 of the strip. When a defined level of wear is reached, the first temperature sensor 2.1 arranged at a first distance from the top 10 of the unworn strip 1 is destroyed. By means of the remaining evaluable temperature signal, the evaluation unit can establish that the temperature sensor 2.1 has been destroyed, and therefore the first level of wear has been reached. Data from the control unit 3 can be transmitted to an evaluation unit 500 via a transmission device. In the sealing device illustrated in FIG. 6, the transmission is carried out in a cable-free manner. However, a cable-based data transmission can also be imagined. Since the strip holder 3 does not rotate during operation of the suction roll, a cable can be led comparatively simply out of the strip 1.

[0092] The roll cover 100 in a suction roll is provided with a multiplicity of drilled holes. Through these drilled holes, moisture from the fibrous web or clothing can reach the interior of the suction roll, and therefore also the sealing strip 1. In addition, moistening devices are usually provided in such suction rolls in order to introduce a lubricant—as a rule water—between the roll cover 100 and the top 10 of the sealing strip 1. Thus, during operation of the sealing device, the top 10 of the sealing strip 1 is always in contact with moisture. As a temperature sensor 2.1 wears, a weak point is then produced, through which the moisture can penetrate into the interior of the strip 1 as far as the control unit 3 or still intact sensors. The protective material 30 into which the temperature sensor 2.1 prevents or hampers this penetration of moisture and, as a result, significantly increases the service life of the sensor unit 2 in a simple and cost-effective way.

[0093] The examples shown should once more illustrate the possibilities which result within the context of the invention. However, the invention is not restricted to these embodiments. In particular, other suitable types of T sensors can also be used instead of the temperature sensors.

LIST OF REFERENCE SYMBOLS

[0094] 1 Sealing strip [0095] 2 Sensor unit [0096] 2.1 First temperature sensor [0097] 2.2 Second temperature sensor [0098] 2.3 Third temperature sensor [0099] 2.4 Fourth temperature sensor [0100] 3 Control unit [0101] 4 Power supply [0102] 5 Circuit board [0103] 5.1 Circuit board [0104] 6 Incision [0105] 7 Line [0106] 10 Top [0107] 11 Underside [0108] 20 Base material [0109] 30 Protective material [0110] 100 Roll cover [0111] 200 Negative pressure zone [0112] 300 Strip holder [0113] 350 Pressure hose [0114] 500 Evaluation unit