Sealing device for detecting the thickness of a sealing element of a seal

Abstract

Sealing device for detecting the thickness of a sealing element. 【Solution means】The sealing surface 3 on the front surface of the sealing element 2 is in sliding contact with the surface to be sealed 4, and the component 10 around the surface to be sealed 4 and / or the component 7 to which the seal 1 is attached are arranged to move in the longitudinal direction of the sealing element 2. The surface to be sealed 4 is the surface of the component 10 around the surface to be sealed 4 where the sealing element 2 abuts against the sealing surface 3. A sensor 5 for measuring the thickness of the sealing element 2 is attached to the component 10 around the surface to be sealed 4. The sensor 5 stays on the opposite side of the sealing element 2 during the thickness measurement of the sealing element 2. The sensor 5 can receive a response from the lateral boundary of the sealing element 2, or from the conductive insert 6, or from the insert 6 of magnetic material. The insert 6 is embedded in the sealing element 2 or connected to the back side of the sealing element 2.

Description

Technical Field

[0001] The present invention relates to a sealing device for detecting the thickness of a sealing element of a seal. Preferably, the seal is pressurized by a fluid or other pressing device, whereby the sealing surfaces of the seal reliably contact adjacent movable sealing surfaces that slide against each other during operation of the sealed component. The present invention also relates to an apparatus for treating a suspension in a pulp or paper manufacturing plant. The scope of the present invention is defined in the claims.

Background Art

[0002] The sealing surfaces of a seal that are in sliding contact with adjacent surfaces to be sealed will ultimately wear. Often, the seal is attached to a continuously operating device, but it is impossible to stop to inspect the amount of wear of the sealing surface. Therefore, there is a strong need to measure the level of wear or at least detect when the sealing surface has worn to a critical thickness. Various methods and devices have been developed for measurement or indication tasks. Some utilize visually detectable features. For these indications, an operator or service technician needs to visually check the seal. In many cases, this is practically impossible.

[0003] Since the seal wears and becomes very thin, electrical connections have also been arranged above or within the sealing material to indicate that it needs to be replaced. Such solutions are described in patent documents such as Patent Document 1 and Patent Document 2. The seal can also be provided with a built-in measuring sensor for measuring the thickness of the sealing surface of the seal at the position of the sensor. Such solutions are described in patent documents such as Patent Document 3, Patent Document 4, and Patent Document 5. Patent Document 6 and Patent Document 7 disclose using the surface to be sealed as the ground electrode of a capacitor and a conductive insert embedded in the seal functioning as the second electrode. Measurement of the capacitance of such a circuit indicates the thickness of the surface to be sealed.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Patent Document 5

Patent Document 6

Patent Document 7

Summary of the Invention

Problems to be Solved by the Invention

[0005] A seal moving relative to the sealing surface may locally wear. Solutions using a sensing method with an embedded open - close connection can detect locally worn sealing elements of the seal. However, they still cannot continuously measure the progression of thickness along the sealing element. The capacitive method can measure the average thickness of the sealing surface. By knowing the wear rate of the seal, the controller can, for example, estimate the wear trend and predict the available operating time before replacing the seal. Also, by measuring the entire length or most of the length of the seal, the locations of rapid wear can be detected and tracked.

[0006] The sealing surface that slides against the sealing element needs to be as uniform as possible in order to avoid surface irregularities that can accelerate wear. Also, in order to avoid local differences in wear rate, the material of the sealing surface needs to be uniform. For example, variations in hardness or metallurgical composition, or surface irregularities, can cause completely different wear rates or local corrosion along the sealing surface. The sealing surface preferably needs to contain only one component in order to avoid boundaries within the sealing surface. Such boundaries can cause leakage even when a new seal is used.

Means for Solving the Problem

[0007] The present invention has been developed to address the need to track the wear of the sealing element of a seal that is in sliding contact with an adjacent sealing surface. The present invention is defined in claim 1, and advantageous embodiments are defined in the dependent claims.

[0008] At least one sensor for detecting the thickness of the sealing element of the seal is attached to a component around the sealing surface. When the sensor is arranged on the opposite side of the sealing element, the sensor can detect and / or measure the thickness along the length of the sealing element. When the component around the sealing surface and / or the component to which the seal is attached rotates or reciprocates, i.e., when they are arranged to move relative to each other in the longitudinal direction of the sealing element, the sensor remains continuously on the opposite side of the sealing surface. The sensor needs to be able to receive a response from a lateral boundary or insert of the sealing element. The insert can be made of a conductive or magnetic material. The insert can be embedded within the sealing element or connected to the back side of the sealing element.

[0009] Even when the sensor contacted the sealing element through a hole in the surface to be sealed, no excessive wear of the sealing element was detected in the test. Also, even when the material of the surface to be sealed and the sensor were different from each other, no differences related to wear of the surface to be sealed were seen when the sealing device was surrounded by lignocellulose or other suspensions in a pulp or paper manufacturing plant. Since the seal may seal against any fluid or particle-containing substance, the same positive results do not necessarily apply to other untested sealing devices and environments. Nevertheless, in continuous operating process equipment such as that used in a pulp or paper manufacturing plant with lignocellulose or other suspensions, it is often preferred to have a controlled but slightly shorter life rather than an assumed but uncontrolled long life.

[0010] The sensor is preferably an ultrasonic sensor. Alternatively, it is also sensitive to changes in inductance or magnetic field. If required or preferred by the sensing method of the sensor, the seal can have an insert within the seal on the back side of the sealing element, or the insert can be embedded within the sealing element. And the insert or the sealing element includes a metal or other conductive material or magnetic material. The conductive fluid on the back side of the sealing element also functions as an insert and enables the operation of the sensor.

[0011] When the sensing end of the sensor is within the hole in the surface to be sealed, it is advantageous for the width or diameter of the sensing end of the sensor to be smaller than the width of the sealing surface that contacts the surface to be sealed. And a part of the sealing surface is not affected by the possible gap formed between the sensing end of the sensor and the surface to be sealed. The sensor is also centered, i.e., located at the center of the sealing element, and there are uniform regions of the surface to be sealed on both sides of the sensing end of the sensor. When the sensor is located at the center of the insert, the device achieves the best sensing results. To achieve a sufficiently uniform surface to be sealed, the height of the sensing end of the sensor needs to be less than 0.1 mm above the surface to be sealed and less than 0.2 mm below the surface to be sealed. More preferably, they are at the same height. Most preferably, the entire surface to be sealed is uniform and the sensor is mounted below the surface to be sealed. Then, no contact occurs between the sensor and the sealing element.

[0012] The pressing force needs to press the sealing element against the surface to be sealed along the entire length of the seal. The pressing force can be achieved by pneumatic, hydraulic, or mechanical means. Preferably, the back side of the sealing element is connected to a source of pressurized fluid via a conduit.

[0013] For beneficial process control advantages, the sensor needs to be connected to the controller of the equipment to which the seal is attached. The controller needs to be configured to report the minimum thickness of the sealing element and / or at least indicate when the measured value and / or the signal received from the sensor indicates that the thickness is thinner than a predetermined limit at any longitudinal position of the sealing element. Preferably, the controller is also configured to report the thickness of the sealing element related to the angular or longitudinal position of the sealing element. When the connection between the sensor and the controller is wireless and they are battery-powered, a power-saving periodic operation is required, so the connection and / or the sensor should not be continuously operated.

Brief Description of the Drawings

[0014]

Figure 1

Figure 2

Figure 3

Embodiments for Carrying Out the Invention

[0015] FIG. 1 shows an embodiment of a sealing device for detecting the thickness t of the sealing element 2 of the seal 1. The sealing surface 3 on the front surface of the sealing element 2 wears and thins when it makes sliding contact with the adjacent sealing surface 4 of the surrounding component 10. The sealing element 2 of the seal is an acting element that restricts leakage between the sealing surface 3 and the sealing surface 4. The other parts of the sealing device mainly prevent leakage between the seal 1 and / or the component 7 to which the seal 1 is attached, and ensure a continuous acting force on the sealing surface 3.

[0016] At least one sensor 5 for indicating the thickness of the sealing element 2 is attached to a component 10 around the surface 4 to be sealed. The component 10 around the surface 4 to be sealed and / or the component 7 to which the seal 1 is attached are arranged to reciprocate or rotate in the longitudinal direction of the sealing element 2 such that the sensor 5 is continuously arranged on the opposite side of the sealing element 2. The sensor 5 is preferably connected to the controller 9 of the device to which the seal 1 is attached. The sensor 5 can also be connected to the display controller and indicator necessary to function as a stand-alone solution. The controller 9 is configured to report the state of the thickness t of the sealing element 2. Preferably, the controller 9 reports at least that the thickness t is too thin if the value and / or corresponding signal received from the sensor 5 indicates that the thickness t is thinner than a predetermined value at any longitudinal position of the sealing element 2. More preferably, the controller 9 is configured to report the thickness t of the sealing element 2 in relation to the angular or longitudinal position of the sealing element 2 at predetermined time intervals.

[0017] When the surrounding component 10, and thus the sealing surface 4, is rotatable, a wireless connection such as Bluetooth®, WLAN, RFID, or other high-frequency, acoustic, or optical wave transmission means may be required to connect the sensor 5 and the controller 9. The wireless transmission can be continuous, or the transmitter can transmit data collected at appropriate intervals such as daily or weekly to conserve battery power. The preferred interval is longer than one hour, and the more preferred interval is daily. The processing and storage of the sensor and sensor data can also be operated at the same or a shorter interval to conserve battery power. At least when processing lignocellulose or other suspensions in a pulp or paper processing plant, wear should not occur quickly. The seal should not wear to a thickness that is too thin within a few days. Usually, a device equipped with such a seal needs to operate continuously for preferably more than one year without replacing the seal. For example, many commercial small sensor devices with a Bluetooth® connection can operate for years without replacing the battery if they are not operating continuously.

[0018] When the sensor 5 is an ultrasonic sensor, it transmits ultrasonic waves to and through the sealing element 2. When the sound hits a lateral stiffer barrier like an insert or another boundary such as the back side of the sealing element 2, it echoes back. The receiver of the sensor 5 detects the time difference between the echo and the transmitted sound. The sound needs to be directed laterally to the surface to be sealed 4. The time difference is proportional to the thickness of the sealing element 2. Since sound easily penetrates metal materials without associated attenuation, the ultrasonic sensor does not need to extend through the component 10 to the surface to be sealed 4. The surface to be sealed 4 can remain uniform, the sensor 5 is attached to the surrounding component 10 and directs ultrasonic waves towards the surface to be sealed 4 and the sealing element 2. The indication echo from the interface between the surface to be sealed and the sealing element 2 has a constant time difference and is filtered out from the reported indications. Since the sealing material is usually soft and does not conduct sound well, a stiffer insert 6 embedded or attached to the back side of the sealing element 2 enhances the echo ability and enables more reliable measurement results. The ultrasonic sensing method can also measure the thickness of the sealing element 2 made of metal or other conductive materials.

[0019] Another advantageous and reliable type of sensor 5 is sensitive to changes in inductance and preferably, the sensor 5 is a proximity sensor. A proximity sensor is configured to detect and notify the presence of an object, preferably the distance to the object.When a metallic material or other conductive material is placed near the coil of the proximity sensor, a change in the inductance of the coil is sensed. The change in inductance is proportional to the thickness t of the sealing element 2. The proximity sensor or a controller connected thereto can notify a numerical or analog value related to the distance. Further, or alternatively, when a nearby object is detected, the state of a switch can be changed or a signal can be transmitted. For the purpose of detection and / or measurement, the object to be detected needs to be conductive. Since the sealing element 2 is not normally conductive, the insert 6 or the sealing element 2 needs to include a metal or other conductive material. The insert 6 is preferably attached or connected to the back side of the sealing element 2 since the insert 6 has to move closer to the sealed surface 4 as the sealing element 2 becomes thinner. A wire, foil, particle, or other type of conductive insert 6 can also be embedded within the sealing element 2. A conductive fluid on the back side of the sealing element 2 can also induce the required detection. The proximity sensor will operate optimally when the sensing end of the sensor fits into a hole in the sealed surface 4. The proximity sensor can also operate properly when the metallic sealed surface is as thin as possible over the sensing end. When the sealed surface 4 is not conductive, there is no need to drill a hole in the sealed surface for the proximity sensor. For example, a strip or sheath of PTFE or a coating of a durable low-friction material can be attached to the surrounding component 10 and the sealed surface 2 is on the strip or sheath or coating. A proximity sensor or other type of sensor 5 can be attached thereunder and still achieve reliable sensitivity.

[0020] The sensor 5 can also detect a change in the thickness t due to a change in the magnetic field. This device can include, for example, an insert 6 or a sealing element 2 containing a magnetic material. Thus, the sensor 5 detects an increase in the magnetic field as the sealing element 2 becomes thinner.

[0021] Advantageously, when the sensor 5 has a sensing end mounted inside the hole of the surface 4 to be sealed, the width or diameter of the preferably flat sensing end of the sensor 5 is smaller than the width of the sealing surface 3. Preferably, the sensor 5 is located at the center of the sealing element 2 and / or the insert 6. The surface 4 to be sealed needs to be smooth without irregularities. Therefore, the height of the sensing end of the sensor 5 needs to be less than 0.1 mm above the surface 4 to be sealed and less than 0.2 mm below the surface 4 to be sealed. Most advantageously, the sensor 5 is mounted under the surface 4 to be sealed.

[0022] Pressurizing the seal is a well - adaptable method for achieving a constant acting force on the sealing element 2. And the back side of the sealing element 2 is connected to a source of pressurized fluid via a conduit 8. Even though specific configurations are disclosed in the embodiment of FIG. 1, their implementation is not limited to pressurized seals. Any other method for ensuring an appropriate acting force on the sealing element 2 is possible using advantageous configurations.

[0023] FIG. 2 shows an embodiment of the present invention in which the sensor 5 is mounted under the surface 4 to be sealed. The sensor 5 may or may not be covered by a replaceable or fixed sheath 12, for example, made of a plastic or metal material. In particular, the ultrasonic sensor 5 can also be mounted in a position opposite to the sealing element 2 on the back side of the surrounding component 10 without a cavity for it.

[0024] FIG. 3 shows an embodiment of the present invention in which the acting force of the sealing element is provided by a spring 11. The spring 11 with a flat base and / or a metal washer under it functions like the insert 6 in FIG. 1 and enables thickness measurement indication of proximity or ultrasonic sensors.

Claims

1. A sealing device for detecting the thickness (t) of a sealing element (2) of a seal (1), wherein a sealing surface (3) on the front surface of the sealing element (2) is arranged to be in sliding contact with a surface to be sealed (4), which means that a component (10) around the surface to be sealed (4) and / or a component (7) to which the seal (1) is attached is arranged to move along the longitudinal direction of the sealing element (2). In the sealing device, The surface to be sealed (4) is the surface of the component (10) around the surface to be sealed (4) where the sealing element (2) abuts against the sealing surface (3). At least one sensor (5) for measuring the thickness of the sealing element (2) is attached to the component (10) around the surface to be sealed (4). The sensor (5) remains on the opposite side of the sealing element (2) during the measurement of the thickness of the sealing element (2). The sensor (5) can receive a response from the lateral boundary of the sealing element (2), or from a conductive insert (6), or from an insert (6) of magnetic material. The insert (6) is embedded in the sealing element (2) or connected to the back side of the sealing element (2). The sealing device is characterized by this.

2. The sealing device according to claim 1, wherein the sensor (5) is an ultrasonic sensor or is sensitive to a change in inductance.

3. The sealing device according to claim 1 or 2, wherein the insert (6) contains a metal or other conductive material, or the insert (6) is a material harder than the sealing element (2).

4. The sealing device according to claim 1, wherein the sensor (5) is sensitive to a change in magnetic field and the insert (6) contains a magnetic material.

5. The sealing device according to any one of claims 1 to 4, wherein the sensor (5) is located at the center of the sealing element (2) and / or the insert (6).

6. The sealing device according to any one of claims 1 to 5, wherein the sensing end of the sensor (5) is attached to a hole in the surface to be sealed (4).

7. The sealing device according to claim 6, wherein the width or diameter of the sensing end of the sensor (5) is smaller than the width of the sealing surface (3).

8. The sealing device according to claim 6 or 7, wherein the height of the sensing end of the sensor (5) is less than 0.1 mm above the surface to be sealed (4) and less than 0.2 mm below the surface to be sealed (4).

9. The sealing device according to any one of claims 1 to 5, wherein the sensor (5) is attached to the surrounding component (10) under the surface to be sealed (4).

10. The sealing device according to any one of claims 1 to 9, wherein the back side of the sealing element (2) is connected to a source of pressurized fluid via a conduit (8).

11. The sealing device according to any one of claims 1 to 10, wherein there is a conductive fluid on the back side of the sealing element (2).

12. The sensor (5) is connected to a controller (9) of a device to which the seal (1) is attached, and the controller (9) is configured to report the thickness (t) of the sealing element (2) when at least 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 position of the sealing element (2). The sealing device according to any one of claims 1 to 11.

13. The sealing device according to claim 12, wherein the controller (9) is configured to report the thickness (t) of the sealing element (2) related to the angular or longitudinal position of the sealing element (2) at predetermined time intervals.

14. The sealing device according to claim 13, wherein the sensor (5) is activated for thickness detection and / or the detected indication is wirelessly transmitted to the controller (9) at intervals longer than 1 hour or at intervals of once a day or more.

15. A device for treating lignocellulose or other suspensions in a pulp or paper manufacturing plant, the device having the sealing device according to any one of claims 1 to 14.

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