A SEALING ARRANGEMENT FOR DETECTING THICKNESS OF A SEALING ELEMENT OF A SEAL

Abstract

A sealing arrangement for detecting thickness (t) of a sealing element (2) of a seal (1) wherein the sealing surface (3) at frontside of the sealing element (2) is arranged to be in sliding contact with sealed surface (4), wherein at least one sensor (5) measures the thickness of the sealing element (2) and is mounted to the surrounding component (10) of the sealed surface (4). The sensor (5) is positioned opposite the sealing element (2). The sensor (5) receives a response from a transverse border of the sealing element (2) or from an electrically conductive insert (6) or from an insert (6) of magnetic material, which insert (6) is embedded within the sealing element (2) or is connected to the backside of the sealing element (2). The thickness (t) is detected and/or measured along the length of the sealing element (2).

Claims

1. A sealing arrangement for detecting a thickness of a sealing element of a seal within a component, wherein a sealing surface at front side of the sealing element is arranged to be in sliding contact with a sealed surface of a surrounding component adjacent the component, wherein the seal is mounted to move along a longitudinal direction of the sealing element, wherein at least one sensor is configured to measure the thickness of the sealing element and the sensor is mounted in the surrounding component, and the sensor is positioned opposite to the sealing element during the detection of thickness of the sealing element, and the sensor is configured to detect a transverse border of the sealing element or an insert embedded within the sealing element or connected to a backside of the sealing element.

2. The sealing arrangement of claim 1, wherein the sensor is an ultrasonic sensor or is sensitive to changes of inductance.

3. The sealing arrangement of claim 1, wherein the insert comprises metal or other electrically conductive material or the insert is a harder material than the sealing element.

4. The sealing arrangement of claim 1, wherein the sensor is sensitive to changes of magnetic field and the insert comprises a magnetic material.

5. The sealing arrangement of claim 1, wherein the sensor is centered with respect to the sealing element and/or the insert.

6. The sealing arrangement of claim 1, wherein a sensing end of the sensor is mounted in a hole of the sealed surface.

7. The sealing arrangement of claim 6, wherein a width or a diameter of the sensing end of the sensor is less than a width of the sealing surface.

8. The sealing arrangement of claim 6, wherein the sensing end of the sensor is positioned related to the sealed surface in a range of 0.1 mm above the sealed surface and 0.2 mm below the sealed surface.

9. The sealing arrangement claim 1, wherein the sensor is under the sealed surface and attached to the surrounding component.

10. The sealing arrangement of claim 1, wherein the backside of the sealing element is connected via a conduit to a source of pressurized fluid.

11. The sealing arrangement of claim 1, wherein at the sealing element includes a chamber having a front open to the sealed surface and in fluid communication with a source of an electrically conductive fluid.

12. The sealing arrangement of claim 1, wherein the sensor is connected to a controller of the device, and the controller is configured to report the thickness the sealing element, at least when a value and/or a corresponding signal received from the sensor indicates that the thickness is thinner than a predetermined value at any longitudinal location of the sealing element.

13. The sealing arrangement of claim 12, we controller is configured to periodically report the thickness of the sealing element related to angular or longitudinal locations of the sealing element.

14. The sealing arrangement of claim 12, wherein the sensor is activated for detection of the thickness and is configured to wirelessly transmit data indicating the thickness to the controller at periods greater than an hour.

15. A device for processing lignocellulosic or other suspension of a pulp or paper production plant, which device has the sealing arrangement of claim 1.

16. A sealing arrangement comprising: a first component having a first surface; a second component having a second surface facing the first surface, wherein the second component and the second surface move relative to the first component and the first surface along a movement direction; a sealing element embedded in the first sealing surface and having a first width along a direction orthogonal to the movement direction, wherein the sealing element spans a gap between the first surface and the second surface, and the first sealing surface is in sliding engagement with the second surface across the first width of the sealing element; and a sensor embedded in the second surface and having a sensing surface facing the first sealing surface, a width of the sensing surface is narrower than the first width such that portions of the first width of the sealing element extend beyond the sensing surface along the direction orthogonal to the movement direction, and the sensor is configured to detect a thickness of the of the sealing element, wherein the thickness is along a direction orthogonal to the movement direction and to the first width.

17. The sealing arrangement of claim 16, further comprising an insert abutting a backside of the sealing element, wherein the thickness of the sealing element is a distance between the insert and the first sealing surface, wherein the sensor is configured to detect the thickness by detecting a position of the insert relative to the sensing surface.

18. The sealing arrangement of claim 17, wherein the insert is at least one of a magnetic material, a conductive material and a material having a hardness greater than a hardness of the sealing element.

19. The sealing arrangement of claim 16, further comprising a controller configured to wirelessly from the sensor data indicative of the thickness from the sensor and generate a report indicating the thickness.

20. A method of monitoring sealing arrangement comprising: sealing with a sealing element a gap between a first surface of a first component and a second surface of a second component moving along a movement direction relative to the first component, wherein the sealing element embedded in the first sealing surface and includes a first width along a direction orthogonal to the movement direction, and the sealing element spans the gap such that the first sealing surface is in sliding engagement with the second surface across the first width of the sealing element; repeatedly sensing a thickness of the sealing element along an entire length of the sealing element by a sensor embedded in the second surface and having a sensing surface facing the first sealing surface, a width of the sensing surface narrower than the first width such that portions of the first width extend beyond the sensing surface along the direction orthogonal to the movement direction, wherein the thickness is along a direction orthogonal to the movement direction and to the first width, and periodically reporting a thickness value indicative of the sensed thickness along the entire length of the sealing element.

Description

LIST OF DRAWINGS

[0013] FIG. 1 illustrates an embodiment of the invention wherein a seal is pressurized,

[0014] FIG. 2 illustrates an embodiment of the invention, wherein the sensor is attached under the sealed surface and

[0015] FIG. 3 illustrates an embodiment of the invention wherein force for pressing a seal is arranged by a spring.

DETAILED DESCRIPTION OF THE INVENTION

[0016] FIG. 1. Illustrates an embodiment of a sealing arrangement for detecting thickness t of a sealing element 2 of a seal 1. Sealing surface 3 at frontside of the sealing element 2 wears and gets thinner when it is in sliding contact with adjacent sealed surface 4 of surrounding component 10. The sealing element 2 of the seal is the acting element, which restricts leaking between the sealing surface 3 and the sealed surface 4. The other parts of the sealing arrangement are mainly for preventing leaking between the seal 1 and or the component 7 wherein the seal 1 is mounted and for ensuring continuous acting force to the sealing surface 3.

[0017] At least one sensor 5 for indicating the thickness of the sealing element 2 is mounted to the surrounding component 10 of the sealed surface 4. The surrounding component 10 of the sealed surface 4 and/or the component 7 wherein the seal 1 is mounted is arranged to reciprocate or to rotate in the longitudinal direction of the sealing element 2, so that the sensor 5 is continuously positioned opposite to the sealing element 2. The sensor 5 is preferably connected to a controller 9 of the device, wherein the seal 1 is mounted. The sensor 5 may also be connected to needed indicative controllers and indicators for acting as a stand alone solution. The controller 9 is configured to report the status of thickness t of the sealing element 2. Preferably, the controller 9 at least reports that the thickness t is too thin, when a value and/or a corresponding signal received from the sensor 5 indicates that the thickness t is thinner than a predetermined value at any longitudinal location of the sealing element 2. More preferably the controller 9 is configured to report the thickness t of the sealing element 2 related to angular or longitudinal locations of the sealing element 2 at predetermined time intervals.

[0018] If the surrounding component 10 and thus the sealed surface 4 are rotatable, a wireless connection like Bluetooth, WLAN, RFID or other radio, sound or light wave transmitting means may be needed to connect the sensor 5 and the controller 9. The wireless transmitting can be continuous or the transmitter may transmit collected data at suitable intervals like daily or weekly for saving battery power. A preferred interval is longer than one hour and a more preferable interval is daily. The sensor and sensor data processing and storing may also be operated at the same or shorter intervals for saving battery power. The wearing should not happen fast at least when processing lignocellulosic or other suspensions of a pulp or paper processing plant. A seal should not wear out to too thin thickness within days. Normally the devices with such seals should operate continuously preferably longer than one year without changing the seals. For example, many commercial small sensor devices, which have a Bluetooth connection, are able to operate years without changing batteries, if they are not continuously operated.

[0019] If the sensor 5 is an ultrasonic sensor, it transmits ultrasonic sound against and through the sealing element 2. When the sound hits a transverse harder barrier like an insert or other border like backside of the sealing element 2, it will echo back. A receiver of the sensor 5 detects time difference between the echo and the sent sound. The sound should be directed to transverse direction of the sealed surface 4. The time difference is proportional with the thickness of the sealing element 2. An ultrasonic sensor does not need to extend through the component 10 up to the sealed surface 4 as the sound will penetrate through metallic materials easily without relevant dampening. The sealed surface 4 can stay uniform and the sensor 5 is attached to the surrounding component 10 and directs the ultrasonic sound to the sealed surface 4 and to the sealing element 2. The indicated echo from the interface between the sealed surface and the sealing element 2 will have a constant time difference and will be filtered out of reported indications. As the sealing material is normally soft and do not conduct sound well, a harder insert 6 embedded within or attached to the backside of the sealing element 2 can enhance the echoing capability and enable more reliable measurement results. The ultrasonic sensing method is also able to measure thickness of a sealing element 2, which is made of metal or other conductive material.

[0020] Another advantageous and reliable type of sensor 5 is sensitive to changes of inductance and preferably the sensor 5 is a proximity sensor. A proximity sensor is configured to detect and signal presence of an object and preferably distance to it. When a metallic or other electrically conductive material is positioned close to the coil of the proximity sensor, it senses changes of inductance of the coil. The change of inductance is proportional with the thickness t of the sealing element 2. The proximity sensor or a controller connected to it may signal a numeric or analog value relating to the distance. It may also or instead change status of a switch or send a signal, if a close object has been detected. For the detection and/or measuring purposes, the detected object needs to be electrically conductive. As the sealing elements 2 normally are not conductive, an insert 6 or the sealing element 2 should comprise metal or other electrically conductive material. The insert 6 has to move closer to the sealed surface 4 when the sealing element 2 gets thinner, so it is preferably attached or linked to the backside of the sealing element 2. A wire, a foil, particles or other types of conductive inserts 6 may also be embedded within the sealing element 2. Electrically conductive fluid at the backside of the sealing element 2 can also induce the needed detection. A proximity sensor will operate best, if it is mounted so that the sensing end of the sensor is in a hole of the sealed surface 4. The proximity sensor may also operate adequately, if the metallic sealed surface is as thin as possibly over the sensing end. If the sealed surface 4 is not electrically conductive, there is no need to have a hole in the sealed surface for the proximity sensor. For example a strip or sheath of PTFE or a coating of durable low friction material can be mounted on the surrounding component 10 and the sealed surface 2 will be on the strip or sheath or coating. The proximity sensor or other type of sensor 5 can be mounted under it and still achieve reliable sensitivity.

[0021] A sensor 5 may also detect the change of thickness t by change of magnetic field. The arrangement can comprise for example an insert 6 or the sealing element 2, which comprise magnetic material. Thus the sensor 5 will detect increased magnetic field when the sealing element 2 gets thinner.

[0022] Advantageously width or diameter of a preferably flat sensing end of the sensor 5 is less than width of the sealing surface 3, if the sensor 5 has a sensing end attached into a hole of the sealed surface 4. Preferably, the sensor 5 is centered in respect with the sealing element 2 and/or the insert 6. The sealed surface 4 should be smooth without irregularities. Thus, the height of the sensing end of the sensor 5 should be less than 0.1 mm over the sealed surface 4 and less than 0.2 mm below the sealed surface 4. Most advantageously, the sensor 5 is mounted under the sealed surface 4.

[0023] Pressurizing the seal is a fine and adaptive way for achieving constant acting force for the sealing element 2. Then the backside of the sealing element 2 is connected via a conduit 8 to a source of pressurized fluid. Even though the specified features disclosed with the embodiment of FIG. 1, implementing them is not restricted to pressurized seals. Any other ways for ensuring suitable acting force to sealing element 2 are possible with the advantageous features.

[0024] FIG. 2 illustrates an embodiment of the invention, wherein the sensor 5 is attached under the sealed surface 4. The sensor 5 may or may not be covered by a replaceable or fixed sheath 12 of for example plastic or metallic material. Especially an ultrasonic sensor 5 may also be attached without any cavity for it to the backside of the surrounding component 10 to a position opposite to the sealing element 2.

[0025] FIG. 3 illustrates an embodiment of the invention, wherein acting force for the sealing element is arranged by a spring 11. The spring 11, which has a flat base and/or a metallic washer under it, will act like the insert 6 at FIG. 1 and enable thickness measuring indication for proximity or ultrasonic sensors.